Hydrogen bonds in crystalline D-alanine: diffraction and spectroscopic evidence for differences between enantiomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belo, Ezequiel A.; Pereira, Jose E. M.; Freire, Paulo T. C.

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.

Spectroscopic studies of gel grown zinc doped calcium hydrogen phosphate dihydrate crystals

NASA Astrophysics Data System (ADS)

Suryawanshi, V. B.; Chaudhari, R. T.

2018-05-01

The influence of zinc doping on the gel grown calcium hydrogen phosphate dihydrate crystals was studied using the spectroscopic techniques, which included SEM, FTIR and EDAX. It was found that, zinc ions transform the morphology of brushite crystals from rectangular plate shaped crystals to branching microcrystal patterns. However in FT-IR spectroscopy, as compared to undoped brushite crystals few vibrations were shifted to higher value. The observed changes in the vibrations were due to the impact of zinc ions. EDAX techniques is use to determine the percentage composition of elements present in the doped crystals. It revealed that the sample was of a mixed composition.

Hydrogen bonds in crystalline D-alanine: diffraction and spectroscopic evidence for differences between enantiomers

DOE PAGES

Belo, Ezequiel A.; Pereira, Jose E. M.; Freire, Paulo T. C.; ...

2018-01-01

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.

Mg co-ordination with potential carcinogenic molecule acrylamide: Spectroscopic, computational and cytotoxicity studies

NASA Astrophysics Data System (ADS)

Singh, Ranjana; Mishra, Vijay K.; Singh, Hemant K.; Sharma, Gunjan; Koch, Biplob; Singh, Bachcha; Singh, Ranjan K.

2018-03-01

Acrylamide (acr) is a potential toxic molecule produced in thermally processed food stuff. Acr-Mg complex has been synthesized chemically and characterized by spectroscopic techniques. The binding sites of acr with Mg were identified by experimental and computational methods. Both experimental and theoretical results suggest that Mg coordinated with the oxygen atom of Cdbnd O group of acr. In-vitro cytotoxicity studies revealed significant decrease in the toxic level of acr-Mg complex as compared to pure acr. The decrease in toxicity on complexation with Mg may be a useful step for future research to reduce the toxicity of acr.

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

PubMed

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

2016-02-05

Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Admittance spectroscopy or deep level transient spectroscopy: A contrasting juxtaposition

NASA Astrophysics Data System (ADS)

Bollmann, Joachim; Venter, Andre

2018-04-01

A comprehensive understanding of defects in semiconductors remains of primary importance. In this paper the effectiveness of two of the most commonly used semiconductor defect spectroscopy techniques, viz. deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) are reviewed. The analysis of defects present in commercially available SiC diodes shows that admittance spectroscopy allows the identification of deep traps with reduced measurement effort compared to deep Level Transient Spectroscopy (DLTS). Besides the N-donor, well-studied intrinsic defects were detected in these diodes. Determination of their activation energy and defect density, using the two techniques, confirm that the sensitivity of AS is comparable to that of DLTS while, due to its well defined peak shape, the spectroscopic resolution is superior. Additionally, admittance spectroscopy can analyze faster emission processes which make the study of shallow defects more practical and even that of shallow dopant levels, possible. A comparative summary for the relevant spectroscopic features of the two capacitance methods are presented.

Spectroscopic and electric dipole properties of Sr+Ar and SrAr systems including high excited states

NASA Astrophysics Data System (ADS)

Hamdi, Rafika; Abdessalem, Kawther; Dardouri, Riadh; Al-Ghamdi, Attieh A.; Oujia, Brahim; Gadéa, Florent Xavier

2018-01-01

The spectroscopic properties of the fundamental and several excited states of Sr+Ar and SrAr, Van der Waals systems are investigated by employing an ab initio method in a pseudo-potential approach. The potential energy curves and the spectroscopic parameters are displayed for the 1-10 2Σ+, 1-6 2Π and 1-3 2Δ electronic states of the Sr+Ar molecule and for the 1-6 1Σ+, 1-4 3Σ+, 1-3 1,3Π and 1-3 1,3Δ states of the neutral molecule SrAr. In addition, from these curves, the vibrational levels and their energy spacing are deduced for Σ+, Π and Δ symmetries. The spectra of the permanent and transition dipole moments are studied for the 1,3Σ+ states of SrAr, which are considered to be two-electron systems and 2Σ+ states of the single electron Sr+Ar ion. The spectroscopic parameters obtained for each molecular system are compared with previous theoretical and experimental works. A significant correlation revealed the accuracy of our results.

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

NASA Astrophysics Data System (ADS)

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

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genest-Beaulieu, C.; Bergeron, P., E-mail: genest@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca

We present a comparative analysis of atmospheric parameters obtained with the so-called photometric and spectroscopic techniques. Photometric and spectroscopic data for 1360 DA white dwarfs from the Sloan Digital Sky Survey (SDSS) are used, as well as spectroscopic data from the Villanova White Dwarf Catalog. We first test the calibration of the ugriz photometric system by using model atmosphere fits to observed data. Our photometric analysis indicates that the ugriz photometry appears well calibrated when the SDSS to AB{sub 95} zeropoint corrections are applied. The spectroscopic analysis of the same data set reveals that the so-called high-log g problem canmore » be solved by applying published correction functions that take into account three-dimensional hydrodynamical effects. However, a comparison between the SDSS and the White Dwarf Catalog spectra also suggests that the SDSS spectra still suffer from a small calibration problem. We then compare the atmospheric parameters obtained from both fitting techniques and show that the photometric temperatures are systematically lower than those obtained from spectroscopic data. This systematic offset may be linked to the hydrogen line profiles used in the model atmospheres. We finally present the results of an analysis aimed at measuring surface gravities using photometric data only.« less

Co2 + interaction with Azospirillum brasilense Sp7 cells: a 57Co emission Mössbauer spectroscopic study

NASA Astrophysics Data System (ADS)

Kamnev, Alexander A.; Tugarova, Anna V.; Biró, Borbála; Kovács, Krisztina; Homonnay, Zoltán; Kuzmann, Ernő; Vértes, Attila

2012-03-01

Preliminary 57Co emission Mössbauer spectroscopic data were obtained for the soil bacterium Azospirillum brasilense Sp7 ( T = 80 K) in frozen 57Co2 + -containing suspensions and in their dried residues. The Mössbauer parameters were compared with those for A. brasilense strain Sp245 differing from strain Sp7 by ecological behaviour. Live cells of both strains showed metabolic transformations of 57Co2 + within an hour. Differences in the parameters observed for the two strains under similar conditions suggest dissimilarities in their metabolic response to Co2 + .

Decreased energy demanding processes in the frontal lobes of schizophrenics due to neuroleptics? A 31P-magneto-resonance spectroscopic study.

PubMed

Volz, H P; Rzanny, R; Rössger, G; Hübner, G; Kreitschmann-Andermahr, I; Kaiser, W A; Sauer, H

1997-12-30

In the present investigation on 31P-magneto-resonance spectroscopic parameters in the frontal lobe, we found phosphocreatine levels and the ratio phosphocreatine/adenosine triphosphate to be increased (12.62 +/- 1.98% resp. 0.31 +/- 0.06) in 50 neuroleptic-treated schizophrenics, whereas no differences were detected in 10 neuroleptic-free patients (11.66 +/- 2.57% resp. 0.29 +/- 0.08) compared to 36 controls (11.37 +/- 1.45 resp. 0.29 +/- 0.04). This result points to a major role of neuroleptics in the metabolism of high-energy phosphates.

A convolutional neural network to filter artifacts in spectroscopic MRI.

PubMed

Gurbani, Saumya S; Schreibmann, Eduard; Maudsley, Andrew A; Cordova, James Scott; Soher, Brian J; Poptani, Harish; Verma, Gaurav; Barker, Peter B; Shim, Hyunsuk; Cooper, Lee A D

2018-03-09

Proton MRSI is a noninvasive modality capable of generating volumetric maps of in vivo tissue metabolism without the need for ionizing radiation or injected contrast agent. Magnetic resonance spectroscopic imaging has been shown to be a viable imaging modality for studying several neuropathologies. However, a key hurdle in the routine clinical adoption of MRSI is the presence of spectral artifacts that can arise from a number of sources, possibly leading to false information. A deep learning model was developed that was capable of identifying and filtering out poor quality spectra. The core of the model used a tiled convolutional neural network that analyzed frequency-domain spectra to detect artifacts. When compared with a panel of MRS experts, our convolutional neural network achieved high sensitivity and specificity with an area under the curve of 0.95. A visualization scheme was implemented to better understand how the convolutional neural network made its judgement on single-voxel or multivoxel MRSI, and the convolutional neural network was embedded into a pipeline capable of producing whole-brain spectroscopic MRI volumes in real time. The fully automated method for assessment of spectral quality provides a valuable tool to support clinical MRSI or spectroscopic MRI studies for use in fields such as adaptive radiation therapy planning. © 2018 International Society for Magnetic Resonance in Medicine.

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

NASA Astrophysics Data System (ADS)

Lewis, Benjamin; Pierce, Donna; Cochran, Anita

2015-11-01

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

Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

NASA Astrophysics Data System (ADS)

Carr, J. K.; Zabuga, A. V.; Roy, S.; Rizzo, T. R.; Skinner, J. L.

2014-06-01

The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed "maps," which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala)5-Lys-H+ in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly 13C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and 13C18O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm-1 for both frequencies and couplings, having larger errors only for the frequencies of terminal amides.

Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

PubMed Central

Carr, J. K.; Zabuga, A. V.; Roy, S.; Rizzo, T. R.; Skinner, J. L.

2014-01-01

The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed “maps,” which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala)5-Lys-H+ in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly 13C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and 13C18O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm−1 for both frequencies and couplings, having larger errors only for the frequencies of terminal amides. PMID:24929378

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

NASA Astrophysics Data System (ADS)

Manciu, Felicia

2012-10-01

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.

Absorbent properties of carboxymethylated fiber, hydroentangled nonwoven and regenerated cellulose: a comparative study

USDA-ARS?s Scientific Manuscript database

Commercially-available, bleached cotton fibers, rayon, and their hydroentangled counterparts were carboxymethylated to produce cellulosic products with increased absorbency. These cellulose materials were tested for absorbance, spectroscopic properties, degree of substitution and carding ability. Ca...

A Markov random field based approach to the identification of meat and bone meal in feed by near-infrared spectroscopic imaging.

PubMed

Jiang, Xunpeng; Yang, Zengling; Han, Lujia

2014-07-01

Contaminated meat and bone meal (MBM) in animal feedstuff has been the source of bovine spongiform encephalopathy (BSE) disease in cattle, leading to a ban in its use, so methods for its detection are essential. In this study, five pure feed and five pure MBM samples were used to prepare two sets of sample arrangements: set A for investigating the discrimination of individual feed/MBM particles and set B for larger numbers of overlapping particles. The two sets were used to test a Markov random field (MRF)-based approach. A Fourier transform infrared (FT-IR) imaging system was used for data acquisition. The spatial resolution of the near-infrared (NIR) spectroscopic image was 25 μm × 25 μm. Each spectrum was the average of 16 scans across the wavenumber range 7,000-4,000 cm(-1), at intervals of 8 cm(-1). This study introduces an innovative approach to analyzing NIR spectroscopic images: an MRF-based approach has been developed using the iterated conditional mode (ICM) algorithm, integrating initial labeling-derived results from support vector machine discriminant analysis (SVMDA) and observation data derived from the results of principal component analysis (PCA). The results showed that MBM covered by feed could be successfully recognized with an overall accuracy of 86.59% and a Kappa coefficient of 0.68. Compared with conventional methods, the MRF-based approach is capable of extracting spectral information combined with spatial information from NIR spectroscopic images. This new approach enhances the identification of MBM using NIR spectroscopic imaging.

Rapid measurement of human milk macronutrients in the neonatal intensive care unit: accuracy and precision of fourier transform mid-infrared spectroscopy.

PubMed

Smilowitz, Jennifer T; Gho, Deborah S; Mirmiran, Majid; German, J Bruce; Underwood, Mark A

2014-05-01

Although it is well established that human milk varies widely in macronutrient content, it remains common for human milk fortification for premature infants to be based on historic mean values. As a result, those caring for premature infants often underestimate protein intake. Rapid precise measurement of human milk protein, fat, and lactose to allow individualized fortification has been proposed for decades but remains elusive due to technical challenges. This study aimed to evaluate the accuracy and precision of a Fourier transform (FT) mid-infrared (IR) spectroscope in the neonatal intensive care unit to measure human milk fat, total protein, lactose, and calculated energy compared with standard chemical analyses. One hundred sixteen breast milk samples across lactation stages from women who delivered at term (n = 69) and preterm (n = 5) were analyzed with the FT mid-IR spectroscope and with standard chemical methods. Ten of the samples were tested in replicate using the FT mid-IR spectroscope to determine repeatability. The agreement between the FT mid-IR spectroscope analysis and reference methods was high for protein and fat and moderate for lactose and energy. The intra-assay coefficients of variation for all outcomes were less than 3%. The FT mid-IR spectroscope demonstrated high accuracy in measurement of total protein and fat of preterm and term milk with high precision.

A COMPARISON OF GALAXY COUNTING TECHNIQUES IN SPECTROSCOPICALLY UNDERSAMPLED REGIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Specian, Mike A.; Szalay, Alex S., E-mail: mspecia1@jhu.edu, E-mail: szalay@jhu.edu

2016-11-01

Accurate measures of galactic overdensities are invaluable for precision cosmology. Obtaining these measurements is complicated when members of one’s galaxy sample lack radial depths, most commonly derived via spectroscopic redshifts. In this paper, we utilize the Sloan Digital Sky Survey’s Main Galaxy Sample to compare seven methods of counting galaxies in cells when many of those galaxies lack redshifts. These methods fall into three categories: assigning galaxies discrete redshifts, scaling the numbers counted using regions’ spectroscopic completeness properties, and employing probabilistic techniques. We split spectroscopically undersampled regions into three types—those inside the spectroscopic footprint, those outside but adjacent to it,more » and those distant from it. Through Monte Carlo simulations, we demonstrate that the preferred counting techniques are a function of region type, cell size, and redshift. We conclude by reporting optimal counting strategies under a variety of conditions.« less

Spectroscopic mode identification of γ Doradus stars

NASA Astrophysics Data System (ADS)

Brunsden, E.; Pollard, K. R.; Cottrell, P. L.; Wright, D. J.; Cat, P. De

2017-09-01

The g-mode pulsations in γ Doradus stars are identified using time-series colour photometry and high-resolution spectroscopy. For 22 class members the pulsational frequencies and modes are compared. Ground-based spectroscopic and photometric results show good agreement. The prevalence of (1, |1|) modes is noted and examined.

Dual-window dual-bandwidth spectroscopic optical coherence tomography metric for qualitative scatterer size differentiation in tissues.

PubMed

Tay, Benjamin Chia-Meng; Chow, Tzu-Hao; Ng, Beng-Koon; Loh, Thomas Kwok-Seng

2012-09-01

This study investigates the autocorrelation bandwidths of dual-window (DW) optical coherence tomography (OCT) k-space scattering profile of different-sized microspheres and their correlation to scatterer size. A dual-bandwidth spectroscopic metric defined as the ratio of the 10% to 90% autocorrelation bandwidths is found to change monotonically with microsphere size and gives the best contrast enhancement for scatterer size differentiation in the resulting spectroscopic image. A simulation model supports the experimental results and revealed a tradeoff between the smallest detectable scatterer size and the maximum scatterer size in the linear range of the dual-window dual-bandwidth (DWDB) metric, which depends on the choice of the light source optical bandwidth. Spectroscopic OCT (SOCT) images of microspheres and tonsil tissue samples based on the proposed DWDB metric showed clear differentiation between different-sized scatterers as compared to those derived from conventional short-time Fourier transform metrics. The DWDB metric significantly improves the contrast in SOCT imaging and can aid the visualization and identification of dissimilar scatterer size in a sample. Potential applications include the early detection of cell nuclear changes in tissue carcinogenesis, the monitoring of healing tendons, and cell proliferation in tissue scaffolds.

PHOTOMETRIC, SPECTROSCOPIC, AND ORBITAL PERIOD STUDY OF THREE EARLY-TYPE SEMI-DETACHED SYSTEMS: XZ AQL, UX HER, AND AT PEG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zola, S.; Baştürk, Ö.; Şenavcı, H. V.

2016-08-01

In this paper, we present a combined photometric, spectroscopic, and orbital period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and AT Peg. As a result, we have derived the absolute parameters of their components and, on that basis, we discuss their evolutionary states. Furthermore, we compare their parameters with those of other binary systems and with theoretical models. An analysis of all available up-to-date times of minima indicated that all three systems studied here show cyclic orbital changes; their origin is discussed in detail. Finally, we performed a frequency analysis for possible pulsational behavior, and asmore » a result we suggest that XZ Aql hosts a δ Scuti component.« less

A modified potential for HO2 with spectroscopic accuracy

NASA Astrophysics Data System (ADS)

Brandão, João; Rio, Carolina M. A.; Tennyson, Jonathan

2009-04-01

Seven ground state potential energy surfaces for the hydroperoxyl radical are compared. The potentials were determined from either high-quality ab initio calculations, fits to spectroscopic data, or a combination of the two approaches. Vibration-rotation calculations are performed on each potential and the results compared with experiment. None of the available potentials is entirely satisfactory although the best spectroscopic results are obtained using the Morse oscillator rigid bender internal dynamics potential [Bunker et al., J. Mol. Spectrosc. 155, 44 (1992)]. We present modifications of the double many-body expansion IV potential of Pastrana et al. [J. Chem. Phys. 94, 8093 (1990)]. These new potentials reproduce the observed vibrational levels and observed vibrational levels and rotational constants, respectively, while preserving the good global properties of the original potential.

Spectroscopic, luminescent and laser properties of nanostructured CaF2:Tm materials

NASA Astrophysics Data System (ADS)

Lyapin, A. A.; Fedorov, P. P.; Garibin, E. A.; Malov, A. V.; Osiko, V. V.; Ryabochkina, P. A.; Ushakov, S. N.

2013-08-01

The laser quality transparent СаF2:Tm fluoride ceramics has been prepared by hot forming. Comparative study of absorption and emission spectra of СаF2:Tm (4 mol.% TmF3) ceramic and single crystal samples demonstrated that these materials possess almost identical spectroscopic properties. Laser oscillations of СаF2:Tm ceramics were obtained at 1898 nm under diode pumping, with the slope efficiency of 5.5%. Also, the continuous-wave (CW) laser have been obtained for СаF2:Tm single crystal at 1890 nm pumped by a diode laser was demonstrated.

Bioavailability enhancement of curcumin by complexation with phosphatidyl choline.

PubMed

Gupta, Nishant Kumar; Dixit, Vinod Kumar

2011-05-01

Curcumin is a major constituent of rhizomes of Curcuma longa. Pharmacokinetic studies of curcumin reveal its poor absorption through intestine. Objective of the present study was to enhance bioavailability of curcumin by its complexation with phosphatidyl choline (PC). Complex of curcumin was prepared with PC and characterized on the basis of solubility, melting point, differential scanning calorimetry, thin layer chromatography, and infrared spectroscopic analysis. Everted intestine sac technique was used to study ex vivo drug absorption of curcumin-PC (CU-PC) complex and plain curcumin. Pharmacokinetic studies were performed in rats, and hepatoprotective activity of CU-PC complex was also compared with curcumin and CU-PC physical mixture in isolated rat hepatocytes. Analytical reports along with spectroscopic data revealed the formation of complex. The results of ex vivo study show that CU-PC complex has significantly increased absorption compared with curcumin, when given in equimolar doses. Complex showed enhanced bioavailability, improved pharmacokinetics, and increased hepatoprotective activity as compared with curcumin or CU-PC physical mixture. Enhanced bioavailability of CU-PC complex may be due to the amphiphilic nature of the complex, which greatly enhance the water and lipid solubility of the curcumin. The present study clearly indicates the superiority of complex over curcumin, in terms of better absorption, enhanced bioavailability, and improved pharmacokinetics. Copyright © 2010 Wiley-Liss, Inc.

DFT calculations on spectroscopic and structural properties of a NLO chromophore

NASA Astrophysics Data System (ADS)

Altürk, Sümeyye; Avci, Davut; Tamer, Ömer; Atalay, Yusuf

2016-03-01

The molecular geometry optimization, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of 2-(1'-(4'''-Methoxyphenyl)-5'-(thien-2″-yl)pyrrol-2'-yl)-1,3-benzothiazole as potential nonlinear optical (NLO) material were calculated using density functional theory (DFT) HSEh1PBE method with 6-311G(d,p) basis set. The best of our knowledge, this study have not been reported to date. Additionally, a detailed vibrational study was performed on the basis of potential energy distribution (PED) using VEDA program. It is noteworthy that NMR chemical shifts are quite useful for understanding the relationship between the molecular structure and electronic properties of molecules. The computed IR and NMR spectra were used to determine the types of the experimental bands observed. Predicted values of structural and spectroscopic parameters of the chromophore were compared with each other so as to display the effects of the different substituents on the spectroscopic and structural properties. Obtained data showed that there is an agreement between the predicted and experimental data.

Confronting the Gaia and NLTE spectroscopic parallaxes for the FGK stars

NASA Astrophysics Data System (ADS)

Sitnova, Tatyana; Mashonkina, Lyudmila; Pakhomov, Yury

2018-04-01

The understanding of the chemical evolution of the Galaxy relies on the stellar chemical composition. Accurate atmospheric parameters is a prerequisite of determination of accurate chemical abundances. For late type stars with known distance, surface gravity (log g) can be calculated from well-known relation between stellar mass, T eff, and absolute bolometric magnitude. This method weakly depends on model atmospheres, and provides reliable log g. However, accurate distances are available for limited number of stars. Another way to determine log g for cool stars is based on ionisation equilibrium, i.e. consistent abundances from lines of neutral and ionised species. In this study we determine atmospheric parameters moving step-by-step from well-studied nearby dwarfs to ultra-metal poor (UMP) giants. In each sample, we select stars with the most reliable T eff based on photometry and the distance-based log g, and compare with spectroscopic gravity calculated taking into account deviations from local thermodinamic equilibrium (LTE). After that, we apply spectroscopic method of log g determination to other stars of the sample with unknown distances.

Spectroscopic properties of Nd3+ doped transparent oxyfluoride glass ceramics.

PubMed

Yu, Yunlong; Chen, Daqin; Ma, En; Wang, Yuansheng; Hu, Zhongjian

2007-07-01

In this paper, the spectroscopic properties of Nd(3+) doped transparent oxyfluoride glass ceramics containing LaF(3) nano-crystals were systematically studied. The formation and distribution of LaF(3) nano-crystals in the glass matrix were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Based on Judd-Ofelt theory, the intensity parameters Omega(t) (t=2, 4, 6), spontaneous emission probability, radiative lifetime, radiative quantum efficiency, width of the emission line and stimulated emission cross-section of Nd(3+) were evaluated. Particularly, the effect of Nd(3+) doping level on them was discussed. With the increase of Nd(3+) concentration in the glass ceramic, the experimental luminescence lifetime, radiative quantum efficiency and stimulated emission cross-section vary from 353.4 micros, 78.3% and 1.86 x 10(-20)cm(2) to 214.7 micros, 39.9% and 1.52 x 10(-20)cm(2), respectively. The comparative study of Nd(3+) spectroscopic parameters in different hosts suggests that the investigated glass ceramic system is potentially applicable as laser materials for 1.06 microm emission.

Growth, structure, Hirshfeld surface and spectroscopic properties of 2-amino-4-hydroxy-6-methylpyrimidinium-2,3-pyrazinedicorboxylate single crystal

NASA Astrophysics Data System (ADS)

Faizan, Mohd; Alam, Mohammad Jane; Afroz, Ziya; Rodrigues, Vítor Hugo Nunes; Ahmad, Shabbir

2018-03-01

The present work is focused on the crystal structure, vibrational spectroscopy and DFT calculations of hydrogen bonded 2,3-pyrazinedicorboxylic acid and 2-amino-4-hydroxy-6-methylpyrimidine (PDCA-.AHMP+) crystal. The crystal structure has been determined using single crystal X-ray diffraction analysis which shows that the crystal belongs to monoclinic space group P21/n. The PDCA-.AHMP+ crystal has been characterized by FTIR, FT-Raman and FT-NMR spectroscopic techniques. The FTIR and FT-Raman spectra of the complex have unique spectroscopic feature as compared with those of the starting material to confirm salt formation. The theoretical vibrational studies have been performed to understand the modes of the vibrations of asymmetric unit of the complex by DFT methods. Hirschfeld surface and 2D fingerprint plots analyses were carried out to investigate the intermolecular interactions and its contribution in the building of PDCA-.AHMP+ crystal. The experimental and simulated 13C and 1H NMR studies have assisted in structural analysis of PDCA-.AHMP+ crystal. The electronic spectroscopic properties of the complex were explored by the experimental as well as theoretical electronic spectra simulated using TD-DFT/IEF-PCM method at B3LYP/6-311++G (d,p) level of theory. In addition, frontier molecular orbitals, molecular electrostatic potential map (MEP) and nonlinear optical (NLO) properties using DFT method have been also presented.

Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carr, J. K.; Roy, S.; Skinner, J. L.

2014-06-14

The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed “maps,” which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental andmore » theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala){sub 5}-Lys-H{sup +} in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly {sup 13}C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and {sup 13}C{sup 18}O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm{sup −1} for both frequencies and couplings, having larger errors only for the frequencies of terminal amides.« less

Evaluation of Heterogeneous Metabolic Profile in an Orthotopic Human Glioblastoma Xenograft Model Using Compressed Sensing Hyperpolarized 3D 13C Magnetic Resonance Spectroscopic Imaging

PubMed Central

Park, Ilwoo; Hu, Simon; Bok, Robert; Ozawa, Tomoko; Ito, Motokazu; Mukherjee, Joydeep; Phillips, Joanna J.; James, C. David; Pieper, Russell O.; Ronen, Sabrina M.; Vigneron, Daniel B.; Nelson, Sarah J.

2013-01-01

High resolution compressed sensing hyperpolarized 13C magnetic resonance spectroscopic imaging was applied in orthotopic human glioblastoma xenografts for quantitative assessment of spatial variations in 13C metabolic profiles and comparison with histopathology. A new compressed sensing sampling design with a factor of 3.72 acceleration was implemented to enable a factor of 4 increase in spatial resolution. Compressed sensing 3D 13C magnetic resonance spectroscopic imaging data were acquired from a phantom and 10 tumor-bearing rats following injection of hyperpolarized [1-13C]-pyruvate using a 3T scanner. The 13C metabolic profiles were compared with hematoxylin and eosin staining and carbonic anhydrase 9 staining. The high-resolution compressed sensing 13C magnetic resonance spectroscopic imaging data enabled the differentiation of distinct 13C metabolite patterns within abnormal tissues with high specificity in similar scan times compared to the fully sampled method. The results from pathology confirmed the different characteristics of 13C metabolic profiles between viable, non-necrotic, nonhypoxic tumor, and necrotic, hypoxic tissue. PMID:22851374

Evaluation of heterogeneous metabolic profile in an orthotopic human glioblastoma xenograft model using compressed sensing hyperpolarized 3D 13C magnetic resonance spectroscopic imaging.

PubMed

Park, Ilwoo; Hu, Simon; Bok, Robert; Ozawa, Tomoko; Ito, Motokazu; Mukherjee, Joydeep; Phillips, Joanna J; James, C David; Pieper, Russell O; Ronen, Sabrina M; Vigneron, Daniel B; Nelson, Sarah J

2013-07-01

High resolution compressed sensing hyperpolarized (13)C magnetic resonance spectroscopic imaging was applied in orthotopic human glioblastoma xenografts for quantitative assessment of spatial variations in (13)C metabolic profiles and comparison with histopathology. A new compressed sensing sampling design with a factor of 3.72 acceleration was implemented to enable a factor of 4 increase in spatial resolution. Compressed sensing 3D (13)C magnetic resonance spectroscopic imaging data were acquired from a phantom and 10 tumor-bearing rats following injection of hyperpolarized [1-(13)C]-pyruvate using a 3T scanner. The (13)C metabolic profiles were compared with hematoxylin and eosin staining and carbonic anhydrase 9 staining. The high-resolution compressed sensing (13)C magnetic resonance spectroscopic imaging data enabled the differentiation of distinct (13)C metabolite patterns within abnormal tissues with high specificity in similar scan times compared to the fully sampled method. The results from pathology confirmed the different characteristics of (13)C metabolic profiles between viable, non-necrotic, nonhypoxic tumor, and necrotic, hypoxic tissue. Copyright © 2012 Wiley Periodicals, Inc.

Comparative study of the interactions between bisphenol-A and its endocrine disrupting analogues with bovine serum albumin using multi-spectroscopic and molecular docking studies.

PubMed

Ikhlas, Shoeb; Usman, Afia; Ahmad, Masood

2018-04-24

Interaction studies of bisphenol analogues; biphenol-A (BPA), bisphenol-B (BPB), and bisphenol-F (BPF) with bovine serum albumin (BSA) were performed using multi-spectroscopic and molecular docking studies at the protein level. The mechanism of binding of bisphenols with BSA was dynamic in nature. SDS refolding experiments demonstrated no stabilization of BSA structure denatured by BPB, however, BSA denatured by BPA and BPF was found to get stabilized. Also, CD spectra and molecular docking studies revealed that BPB bound more strongly and induced more conformational changes in BSA in comparison to BPA. Hence, this study throws light on the replacement of BPA by its analogues and whether the replacement is associated with a possible risk, raising a doubt that perhaps BPB is not a good substitute of BPA.

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

NASA Astrophysics Data System (ADS)

Reid, Piper

2013-01-01

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

Automated processing for proton spectroscopic imaging using water reference deconvolution.

PubMed

Maudsley, A A; Wu, Z; Meyerhoff, D J; Weiner, M W

1994-06-01

Automated formation of MR spectroscopic images (MRSI) is necessary before routine application of these methods is possible for in vivo studies; however, this task is complicated by the presence of spatially dependent instrumental distortions and the complex nature of the MR spectrum. A data processing method is presented for completely automated formation of in vivo proton spectroscopic images, and applied for analysis of human brain metabolites. This procedure uses the water reference deconvolution method (G. A. Morris, J. Magn. Reson. 80, 547(1988)) to correct for line shape distortions caused by instrumental and sample characteristics, followed by parametric spectral analysis. Results for automated image formation were found to compare favorably with operator dependent spectral integration methods. While the water reference deconvolution processing was found to provide good correction of spatially dependent resonance frequency shifts, it was found to be susceptible to errors for correction of line shape distortions. These occur due to differences between the water reference and the metabolite distributions.

Development of Single-Seed Near-Infrared Spectroscopic Predictions of Corn and Soybeans Constituents Using Bulk Teference Values and Mean Spectra

USDA-ARS?s Scientific Manuscript database

Near-Infrared reflectance spectroscopic prediction models were developed for common constituents of corn and soybeans using bulk reference values and mean spectra from single-seeds. The bulk reference model and a true single-seed model for soybean protein were compared to determine how well the bul...

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak P.; Gump, Jared C.

2006-07-01

Explosive formulations with reduced-sensitivity RDX showed reduced shock sensitivity using Naval Ordnance Laboratory (NOL) Large Scale Gap Test, compared with similar formulations using standard RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light on the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. I-RDX®, a form of reduced- sensitivity RDX was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transform IR (FTIR). The pressure dependence of the Raman mode frequencies of I-RDX® was determined and compared with that of standard RDX. The behavior of I-RDX® near the pressure at which standard RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph is presented.

Multispectroscopic and Theoretical Exploration of the Comparative Binding Aspects of Bioflavonoid Fisetin with Triple- and Double-Helical Forms of RNA.

PubMed

Bhuiya, Sutanwi; Haque, Lucy; Goswami, Rapti; Das, Suman

2017-12-14

The interactions of RNA triplex (U.A*U) and duplex (A.U) with naturally occurring flavonoid fisetin (FTN) have been examined at pH 7.0 using various spectroscopic, viscometric, and theoretical studies. Experimental observations showed that the ligand binds with both double- and triple-helical forms of RNA, although the binding affinity is greater for the triplex structure (5.94 × 10 6 M -1 ) compared to that for the duplex counterpart (1.0 × 10 5 M -1 ). Thermal melting experiments revealed that the Hoogsteen base-paired third strand of triplex was stabilized to a greater extent (∼14 °C) compared with the Watson-Crick base-paired second strand (∼4 °C) in the presence of FTN. From fluorimetric study, we observed that U.A*U and A.U primarily bind to the photoproduced tautomer of FTN in the excited state. Steady-state and time-resolved anisotropy measurements illustrate considerable modulations of the spectroscopic properties of the tautomeric FTN within the RNA environment. Viscometric, fluorescence quenching, and thermal melting studies all together support the mode of binding to be intercalation. Theoretical study explains the experimental absorption and emission (dual fluorescence) behavior of FTN along with the excited-state intramolecular proton transfer process.

Synthesis, spectroscopic, crystal structure, biological activities and theoretical studies of 2-[(2E)-2-(2-chloro-6-fluorobenzylidene)hydrazinyl]pyridine

NASA Astrophysics Data System (ADS)

Dilek Özçelik, Nefise; Tunç, Tuncay; Çatak Çelik, Raziye; Erzengin, Mahmut; Özışık, Hacı

2017-05-01

We report in this paper the synthesis, spectroscopic, crystal structure, biological activities and theoretical results of the title compound. The crystal structure was defined by the X-ray diffraction (XRD) method. In addition, this newly synthesized hydrazone derivative was also subjected to its possible antioxidant activity with free radical scavenging ability of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals using butylated hydroxytoluene (BHT) as standard antioxidant. The structural calculations were performed by the density functional theory using the B3LYP method with 6-311++G(2d,2p) basis set. The calculated values were compared with experimental results.

Spectroscopic profiling and computational study of the binding of tschimgine: A natural monoterpene derivative, with calf thymus DNA

NASA Astrophysics Data System (ADS)

Khajeh, Masoumeh Ashrafi; Dehghan, Gholamreza; Dastmalchi, Siavoush; Shaghaghi, Masoomeh; Iranshahi, Mehrdad

2018-03-01

DNA is a major target for a number of anticancer substances. Interaction studies between small molecules and DNA are essential for rational drug designing to influence main biological processes and also introducing new probes for the assay of DNA. Tschimgine (TMG) is a monoterpene derivative with anticancer properties. In the present study we tried to elucidate the interaction of TMG with calf thymus DNA (CT-DNA) using different spectroscopic methods. UV-visible absorption spectrophotometry, fluorescence and circular dichroism (CD) spectroscopies as well as molecular docking study revealed formation of complex between TMG and CT-DNA. Binding constant (Kb) between TMG and DNA was 2.27 × 104 M- 1, that is comparable to groove binding agents. The fluorescence spectroscopic data revealed that the quenching mechanism of fluorescence of TMG by CT-DNA is static quenching. Thermodynamic parameters (ΔH < 0 and ΔS < 0) at different temperatures indicated that van der Waals forces and hydrogen bonds were involved in the binding process of TMG with CT-DNA. Competitive binding assay with methylene blue (MB) and Hoechst 33258 using fluorescence spectroscopy displayed that TMG possibly binds to the minor groove of CT-DNA. These observations were further confirmed by CD spectral analysis, viscosity measurements and molecular docking.

The Rotation of M Dwarfs Observed by the Apache Point Galactic Evolution Experiment

NASA Astrophysics Data System (ADS)

Gilhool, Steven H.; Blake, Cullen H.; Terrien, Ryan C.; Bender, Chad; Mahadevan, Suvrath; Deshpande, Rohit

2018-01-01

We present the results of a spectroscopic analysis of rotational velocities in 714 M-dwarf stars observed by the SDSS-III Apache Point Galactic Evolution Experiment (APOGEE) survey. We use a template-fitting technique to estimate v\\sin i while simultaneously estimating {log}g, [{{M}}/{{H}}], and {T}{eff}. We conservatively estimate that our detection limit is 8 km s‑1. We compare our results to M-dwarf rotation studies in the literature based on both spectroscopic and photometric measurements. Like other authors, we find an increase in the fraction of rapid rotators with decreasing stellar temperature, exemplified by a sharp increase in rotation near the M4 transition to fully convective stellar interiors, which is consistent with the hypothesis that fully convective stars are unable to shed angular momentum as efficiently as those with radiative cores. We compare a sample of targets observed both by APOGEE and the MEarth transiting planet survey and find no cases where the measured v\\sin i and rotation period are physically inconsistent, requiring \\sin i> 1. We compare our spectroscopic results to the fraction of rotators inferred from photometric surveys and find that while the results are broadly consistent, the photometric surveys exhibit a smaller fraction of rotators beyond the M4 transition by a factor of ∼2. We discuss possible reasons for this discrepancy. Given our detection limit, our results are consistent with a bimodal distribution in rotation that is seen in photometric surveys.

Validation of hierarchical cluster analysis for identification of bacterial species using 42 bacterial isolates

NASA Astrophysics Data System (ADS)

Ghebremedhin, Meron; Yesupriya, Shubha; Luka, Janos; Crane, Nicole J.

2015-03-01

Recent studies have demonstrated the potential advantages of the use of Raman spectroscopy in the biomedical field due to its rapidity and noninvasive nature. In this study, Raman spectroscopy is applied as a method for differentiating between bacteria isolates for Gram status and Genus species. We created models for identifying 28 bacterial isolates using spectra collected with a 785 nm laser excitation Raman spectroscopic system. In order to investigate the groupings of these samples, partial least squares discriminant analysis (PLSDA) and hierarchical cluster analysis (HCA) was implemented. In addition, cluster analyses of the isolates were performed using various data types consisting of, biochemical tests, gene sequence alignment, high resolution melt (HRM) analysis and antimicrobial susceptibility tests of minimum inhibitory concentration (MIC) and degree of antimicrobial resistance (SIR). In order to evaluate the ability of these models to correctly classify bacterial isolates using solely Raman spectroscopic data, a set of 14 validation samples were tested using the PLSDA models and consequently the HCA models. External cluster evaluation criteria of purity and Rand index were calculated at different taxonomic levels to compare the performance of clustering using Raman spectra as well as the other datasets. Results showed that Raman spectra performed comparably, and in some cases better than, the other data types with Rand index and purity values up to 0.933 and 0.947, respectively. This study clearly demonstrates that the discrimination of bacterial species using Raman spectroscopic data and hierarchical cluster analysis is possible and has the potential to be a powerful point-of-care tool in clinical settings.

Investigations of Spectroscopic Factors and Sum Rules from the Single Neutron Transfer Reaction 111Cd(overrightarrow {{d}} ,p)112Cd

NASA Astrophysics Data System (ADS)

Jamieson, D. S.; Garrett, P. E.; Ball, G. C.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Krücken, R.; Leach, K. G.; Phillips, A. A.; Sumithrarachchi, C. S.; Triambak, S.; Wirth, H.-F.

2014-03-01

Cadmium isotopes have been presented for decades as excellent examples of vibrational nuclei, with low-lying levels interpreted as multi-phonon quadrupole, octupole, and mixed-symmetry states. A large amount of spectroscopic data has been obtained through various experimental studies of cadmiumisotopes. In the present work, the 111Cd(overrightarrow {{d}} ,p)112Cd reaction was used to investigate the single-particle structure of the 112Cd nucleus. A 22 MeV beam of polarized deuterons was obtained at the Maier-Leibnitz laboratory in Garching, Germany. The reaction ejectiles were momentum analyzed using a Q3D spectrograph, and 130 levels have been identified up to 4.2 MeV of excitation energy. Using DWBA analysis with optical model calculations, spin-parity assignments have been made for observed levels, and spectroscopic factors have been extracted from the experimental angular distributions of differential cross section and analyzing power. In this high energy resolution investigation, many additional levels have been observed compared with the previous (d,p) study using 8 MeV deuterons [1]. There were a total of 44 new levels observed, and the parity assignments of 34 levels were improved.

Pre-phase A: Development of a far-ultraviolet photometric- and spectroscopic-survey small-explorer experiment

NASA Technical Reports Server (NTRS)

Martin, Christopher

1993-01-01

We propose to perform a far ultraviolet photometric and spectroscopic survey covering the lambda lambda 1300-2000 band with a sensitivity comparable to that of the Palomar Sky Survey. This survey will proceed in three phases: an all-sky survey in three bands to 18-19.5(sup m), deep surveys of selected targets of interest in the same bands to 21-22(sup m), and a spectroscopic survey of 2 percent of the sky to 18(sup m) with a resolution of 3-20A. This mission, the Joint Ultraviolet Nightsky Observer (JUNO), can be performed by a Small-Explorer-class satellite.

Applications of QCL mid-IR imaging to the advancement of pathology

NASA Astrophysics Data System (ADS)

Sreedhar, Hari; Varma, Vishal K.; Bird, Benjamin; Guzman, Grace; Walsh, Michael J.

2017-03-01

Quantum Cascade Laser (QCL) spectroscopic imaging is a novel technique with many potential applications to histopathology. Like traditional Fourier Transform Infrared (FT-IR) imaging, QCL spectroscopic imaging derives biochemical data coupled to the spatial information of a tissue sample, and can be used to improve the diagnostic and prognostic value of assessment of a tissue biopsy. This technique also offers advantages over traditional FT-IR imaging, specifically the capacity for discrete frequency and real-time imaging. In this work we present applications of QCL spectroscopic imaging to tissue samples, including discrete frequency imaging, to compare with FT-IR and its potential value to pathology.

X-ray spectroscopic diagnostics and modeling of polar-drive implosion experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Hakel, P.; Kyrala, G. A.; Bradley, P. A.; Krasheninnikova, N. S.; Murphy, T. J.; Schmitt, M. J.; Tregillis, I. L.; Kanzleieter, R. J.; Batha, S. H.; Fontes, C. J.; Sherrill, M. E.; Kilcrease, D. P.; Regan, S. P.

2014-06-01

A series of experiments featuring laser-imploded plastic-shell targets filled with hydrogen or deuterium were performed on the National Ignition Facility. The shells (some deuterated) were doped in selected locations with Cu, Ga, and Ge, whose spectroscopic signals (indicative of local plasma conditions) were collected with a time-integrated, 1-D imaging, spectrally resolved, and absolute-intensity calibrated instrument. The experimental spectra compare well with radiation hydrodynamics simulations post-processed with a non-local thermal equilibrium atomic kinetics and spectroscopic-quality radiation-transport model. The obtained degree of agreement between the modeling and experimental data supports the application of spectroscopic techniques for the determination of plasma conditions, which can ultimately lead to the validation of theoretical models for thermonuclear burn in the presence of mix. Furthermore, the use of a lower-Z dopant element (e.g., Fe) is suggested for future experiments, since the ˜2 keV electron temperatures reached in mixed regions are not high enough to drive sufficient H-like Ge and Cu line emissions needed for spectroscopic plasma diagnostics.

SPECTROSCOPIC ORBITS FOR 15 LATE-TYPE STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Willmarth, Daryl W.; Abt, Helmut A.; Fekel, Francis C.

2016-08-01

Spectroscopic orbital elements are determined for 15 stars with periods from 8 to 6528 days with six orbits computed for the first time. Improved astrometric orbits are computed for two stars and one new orbit is derived. Visual orbits were previously determined for four stars, four stars are members of multiple systems, and five stars have Hipparcos “G” designations or have been resolved by speckle interferometry. For the nine binaries with previous spectroscopic orbits, we determine improved or comparable elements. For HD 28271 and HD 200790, our spectroscopic results support the conclusions of previous authors that the large values of their massmore » functions and lack of detectable secondary spectrum argue for the secondary in each case being a pair of low-mass dwarfs. The orbits given here may be useful in combination with future interferometric and Gaia satellite observations.« less

Spectroscopically Enhanced Method and System for Multi-Factor Biometric Authentication

NASA Astrophysics Data System (ADS)

Pishva, Davar

This paper proposes a spectroscopic method and system for preventing spoofing of biometric authentication. One of its focus is to enhance biometrics authentication with a spectroscopic method in a multifactor manner such that a person's unique ‘spectral signatures’ or ‘spectral factors’ are recorded and compared in addition to a non-spectroscopic biometric signature to reduce the likelihood of imposter getting authenticated. By using the ‘spectral factors’ extracted from reflectance spectra of real fingers and employing cluster analysis, it shows how the authentic fingerprint image presented by a real finger can be distinguished from an authentic fingerprint image embossed on an artificial finger, or molded on a fingertip cover worn by an imposter. This paper also shows how to augment two widely used biometrics systems (fingerprint and iris recognition devices) with spectral biometrics capabilities in a practical manner and without creating much overhead or inconveniencing their users.

Quantitative mapping of total choline in healthy human breast using proton echo planar spectroscopic imaging (PEPSI) at 3 Tesla.

PubMed

Zhao, Chenguang; Bolan, Patrick J; Royce, Melanie; Lakkadi, Navneeth; Eberhardt, Steven; Sillerud, Laurel; Lee, Sang-Joon; Posse, Stefan

2012-11-01

To quantitatively measure tCho levels in healthy breasts using Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI). The two-dimensional mapping of tCho at 3 Tesla across an entire breast slice using PEPSI and a hybrid spectral quantification method based on LCModel fitting and integration of tCho using the fitted spectrum were developed. This method was validated in 19 healthy females and compared with single voxel spectroscopy (SVS) and with PRESS prelocalized conventional Magnetic Resonance Spectroscopic Imaging (MRSI) using identical voxel size (8 cc) and similar scan times (∼7 min). A tCho peak with a signal to noise ratio larger than 2 was detected in 10 subjects using both PEPSI and SVS. The average tCho concentration in these subjects was 0.45 ± 0.2 mmol/kg using PEPSI and 0.48 ± 0.3 mmol/kg using SVS. Comparable results were obtained in two subjects using conventional MRSI. High lipid content in the spectra of nine tCho negative subjects was associated with spectral line broadening of more than 26 Hz, which made tCho detection impossible. Conventional MRSI with PRESS prelocalization in glandular tissue in two of these subjects yielded tCho concentrations comparable to PEPSI. The detection sensitivity of PEPSI is comparable to SVS and conventional PRESS-MRSI. PEPSI can be potentially used in the evaluation of tCho in breast cancer. A tCho threshold concentration value of ∼0.7 mmol/kg might be used to differentiate between cancerous and healthy (or benign) breast tissues based on this work and previous studies. Copyright © 2012 Wiley Periodicals, Inc.

Quantitative Mapping of Total Choline in Healthy Human Breast Using Proton Echo Planar Spectroscopic Imaging (PEPSI) at 3 Tesla

PubMed Central

Zhao, Chenguang; Bolan, Patrick J.; Royce, Melanie; Lakkadi, Navneeth; Eberhardt, Steven; Sillerud, Laurel; Lee, Sang-Joon; Posse, Stefan

2012-01-01

Purpose To quantitatively measure tCho levels in healthy breasts using Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI). Material and Methods The 2-dimensional mapping of tCho at 3 Tesla across an entire breast slice using PEPSI and a hybrid spectral quantification method based on LCModel fitting and integration of tCho using the fitted spectrum were developed. This method was validated in 19 healthy females and compared with single voxel spectroscopy (SVS) and with PRESS prelocalized conventional Magnetic Resonance Spectroscopic Imaging (MRSI) using identical voxel size (8 cc) and similar scan times (~7 min). Results A tCho peak with a signal to noise ratio larger than 2 was detected in 10 subjects using both PEPSI and SVS. The average tCho concentration in these subjects was 0.45 ± 0.2 mmol/kg using PEPSI and 0.48±0.3 mmol/kg using SVS. Comparable results were obtained in 2 subjects using conventional MRSI. High lipid content in the spectra of 9 tCho negative subjects was associated with spectral line broadening of more than 26 Hz, which made tCho detection impossible. Conventional MRSI with PRESS prelocalization in glandular tissue in two of these subjects yielded tCho concentrations comparable to PEPSI. Conclusion The detection sensitivity of PEPSI is comparable to SVS and conventional PRESS-MRSI. PEPSI can be potentially used in the evaluation of tCho in breast cancer. A tCho threshold concentration value of ~0.7mmol/kg might be used to differentiate between cancerous and healthy (or benign) breast tissues based on this work and previous studies. PMID:22782667

Effects of environmental conditions on the ultrafast carrier dynamics in graphene revealed by terahertz spectroscopy

NASA Astrophysics Data System (ADS)

Hafez, H. A.; Chai, X.; Sekine, Y.; Takamura, M.; Oguri, K.; Al-Naib, I.; Dignam, M. M.; Hibino, H.; Ozaki, T.

2017-04-01

A thorough understanding of the stability of graphene under ambient environmental conditions is essential for future graphene-based applications. In this paper, we study the effects of ambient temperature on the properties of monolayer graphene using terahertz time-domain spectroscopy as well as time-resolved terahertz spectroscopy enabled by an optical-pump/terahertz-probe technique. The observations show that graphene is extremely sensitive to the ambient environmental conditions and behaves differently depending on the sample preparation technique and the initial Fermi level. The analysis of the spectroscopic data is supported by van der Pauw and Hall effect measurements of the carrier mobility and carrier density at temperatures comparable to those tested in our THz spectroscopic experiments.

Optical properties of LiGaS2: an ab initio study and spectroscopic ellipsometry measurement

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Lin, Z. S.; Isaenko, L. I.; Kesler, V. G.; Kruchinin, V. N.; Lobanov, S. I.

2009-11-01

Electronic and optical properties of lithium thiogallate crystal, LiGaS2, have been investigated by both experimental and theoretical methods. The plane-wave pseudopotential method based on DFT theory has been used for band structure calculations. The electronic parameters of Ga 3d orbitals have been corrected by the DFT+U methods to be consistent with those measured with x-ray photoemission spectroscopy. Evolution of optical constants of LiGaS2 over a wide spectral range was determined by developed first-principles theory and dispersion curves were compared with optical parameters defined by spectroscopic ellipsometry in the photon energy range 1.2-5.0 eV. Good agreement has been achieved between theoretical and experimental results.

Characterisation of tissue-type metabolic content in secondary progressive multiple sclerosis: a magnetic resonance spectroscopic imaging study.

PubMed

Marshall, Ian; Thrippleton, Michael J; Bastin, Mark E; Mollison, Daisy; Dickie, David A; Chappell, Francesca M; Semple, Scott I K; Cooper, Annette; Pavitt, Sue; Giovannoni, Gavin; Wheeler-Kingshott, Claudia A M Gandini; Solanky, Bhavana S; Weir, Christopher J; Stallard, Nigel; Hawkins, Clive; Sharrack, Basil; Chataway, Jeremy; Connick, Peter; Chandran, Siddharthan

2018-05-30

Proton magnetic resonance spectroscopy yields metabolic information and has proved to be a useful addition to structural imaging in neurological diseases. We applied short-echo time Spectroscopic Imaging in a cohort of 42 patients with secondary progressive multiple sclerosis (SPMS). Linear modelling with respect to brain tissue type yielded metabolite levels that were significantly different in white matter lesions compared with normal-appearing white matter, suggestive of higher myelin turnover (higher choline), higher metabolic rate (higher creatine) and increased glial activity (higher myo-inositol) within the lesions. These findings suggest that the lesions have ongoing cellular activity that is not consistent with the usual assumption of 'chronic' lesions in SPMS, and may represent a target for repair therapies.

Using Spectroscopic Profiles to Study the Morphology of Comets

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

A spectroscopic study on stability of curcumin as a function of pH in silica nanoformulations, liposome and serum protein

NASA Astrophysics Data System (ADS)

Jain, Beena

2017-02-01

The effect of pH on the stability of curcumin formulated with different carriers has been studied spectroscopically. This was investigated by monitoring the absorption and emission kinetics and fluorescence decay time of four different curcumin formulations suspended in buffer with pH varying from 5 to 8.5. The carriers were organically modified silica NP (SiNP) having 3-amino propyl and/or vinyl groups, liposome and serum protein. The results reveal that stability of curcumin formulated with SiNP functionalized with 3-amino propyl group (SiNP-VA) is significantly higher as compared to SiNP with only vinyl group (SiNP-V) and buffer but lower as compared to serum protein and liposome. However, fluorescence quantum yield (QY) is highest in SiNP-VA among all the nano formulations at pH 7.4 and below, which is attributed to the excited state interaction of curcumin with the amino groups of SiNP-VA. Results suggest that SiNP-VA could be an effective carrier for curcumin, which may have applications for imaging and drug delivery.

Comparison of structure and organization of cutaneous lipids in a reconstructed skin model and human skin: spectroscopic imaging and chromatographic profiling.

PubMed

Tfayli, Ali; Bonnier, Franck; Farhane, Zeineb; Libong, Danielle; Byrne, Hugh J; Baillet-Guffroy, Arlette

2014-06-01

The use of animals for scientific research is increasingly restricted by legislation, increasing the demand for human skin models. These constructs present comparable bulk lipid content to human skin. However, their permeability is significantly higher, limiting their applicability as models of barrier function, although the molecular origins of this reduced barrier function remain unclear. This study analyses the stratum corneum (SC) of one such commercially available reconstructed skin model (RSM) compared with human SC by spectroscopic imaging and chromatographic profiling. Total lipid composition was compared by chromatographic analysis (HPLC). Raman spectroscopy was used to evaluate the conformational order, lateral packing and distribution of lipids in the surface and skin/RSM sections. Although HPLC indicates that all SC lipid classes are present, significant differences are observed in ceramide profiles. Raman imaging demonstrated that the RSM lipids are distributed in a non-continuous matrix, providing a better understanding of the limited barrier function. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Optical and laser spectroscopic diagnostics for energy applications

NASA Astrophysics Data System (ADS)

Tripathi, Markandey Mani

The continuing need for greater energy security and energy independence has motivated researchers to develop new energy technologies for better energy resource management and efficient energy usage. The focus of this dissertation is the development of optical (spectroscopic) sensing methodologies for various fuels, and energy applications. A fiber-optic NIR sensing methodology was developed for predicting water content in bio-oil. The feasibility of using the designed near infrared (NIR) system for estimating water content in bio-oil was tested by applying multivariate analysis to NIR spectral data. The calibration results demonstrated that the spectral information can successfully predict the bio-oil water content (from 16% to 36%). The effect of ultraviolet (UV) light on the chemical stability of bio-oil was studied by employing laser-induced fluorescence (LIF) spectroscopy. To simulate the UV light exposure, a laser in the UV region (325 nm) was employed for bio-oil excitation. The LIF, as a signature of chemical change, was recorded from bio-oil. From this study, it was concluded that phenols present in the bio-oil show chemical instability, when exposed to UV light. A laser-induced breakdown spectroscopy (LIBS)-based optical sensor was designed, developed, and tested for detection of four important trace impurities in rocket fuel (hydrogen). The sensor can simultaneously measure the concentrations of nitrogen, argon, oxygen, and helium in hydrogen from storage tanks and supply lines. The sensor had estimated lower detection limits of 80 ppm for nitrogen, 97 ppm for argon, 10 ppm for oxygen, and 25 ppm for helium. A chemiluminescence-based spectroscopic diagnostics were performed to measure equivalence ratios in methane-air premixed flames. A partial least-squares regression (PLS-R)-based multivariate sensing methodology was investigated. It was found that the equivalence ratios predicted with the PLS-R-based multivariate calibration model matched with the experimentally measured equivalence ratios within 7 %. A comparative study was performed for equivalence ratios measurement in atmospheric premixed methane-air flames with ungated LIBS and chemiluminescence spectroscopy. It was reported that LIBS-based calibration, which carries spectroscopic information from a "point-like-volume," provides better predictions of equivalence ratios compared to chemiluminescence-based calibration, which is essentially a "line-of-sight" measurement.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhoads, James E.; Malhotra, Sangeeta; Cohen, Seth

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

Multi-Vendor Implementation and Comparison of Volumetric Whole-Brain Echo-Planar MR Spectroscopic Imaging

PubMed Central

Sabati, Mohammad; Sheriff, Sulaiman; Gu, Meng; Wei, Juan; Zhu, Henry; Barker, Peter B.; Spielman, Daniel M.; Alger, Jeffry R.; Maudsley, Andrew A.

2014-01-01

Purpose To assess volumetric proton MR spectroscopic imaging of the human brain on multi-vendor MRI instruments. Methods Echo-planar spectroscopic imaging (EPSI) was developed on instruments from three manufacturers, with matched specifications and acquisition protocols that accounted for differences in sampling performance, RF power, and data formats. Inter-site reproducibility was evaluated for signal-normalized maps of N-acetylaspartate (NAA), Creatine (Cre) and Choline using phantom and human subject measurements. Comparative analyses included metrics for spectral quality, spatial coverage, and mean values in atlas-registered brain regions. Results Inter-site differences for phantom measurements were under 1.7% for individual metabolites and 0.2% for ratio measurements. Spatial uniformity ranged from 79% to 91%. The human studies found differences of mean values in the temporal lobe, but good agreement in other white-matter regions, with maximum differences relative to their mean of under 3.2%. For NAA/Cre, the maximum difference was 1.8%. In grey-matter a significant difference was observed for frontal lobe NAA. Primary causes of inter-site differences were attributed to shim quality, B0 drift, and accuracy of RF excitation. Correlation coefficients for measurements at each site were over 0.60, indicating good reliability. Conclusion A volumetric intensity-normalized MRSI acquisition can be implemented in a comparable manner across multi-vendor MR instruments. PMID:25354190

Multivendor implementation and comparison of volumetric whole-brain echo-planar MR spectroscopic imaging.

PubMed

Sabati, Mohammad; Sheriff, Sulaiman; Gu, Meng; Wei, Juan; Zhu, Henry; Barker, Peter B; Spielman, Daniel M; Alger, Jeffry R; Maudsley, Andrew A

2015-11-01

To assess volumetric proton MR spectroscopic imaging (MRSI) of the human brain on multivendor MRI instruments. Echo-planar spectroscopic imaging was developed on instruments from three manufacturers, with matched specifications and acquisition protocols that accounted for differences in sampling performance, radiofrequency (RF) power, and data formats. Intersite reproducibility was evaluated for signal-normalized maps of N-acetylaspartate (NAA), creatine (Cre), and choline using phantom and human subject measurements. Comparative analyses included metrics for spectral quality, spatial coverage, and mean values in atlas-registered brain regions. Intersite differences for phantom measurements were less than 1.7% for individual metabolites and less than 0.2% for ratio measurements. Spatial uniformity ranged from 79% to 91%. The human studies found differences of mean values in the temporal lobe, but good agreement in other white matter regions, with maximum differences relative to their mean of under 3.2%. For NAA/Cre, the maximum difference was 1.8%. In gray matter, a significant difference was observed for frontal lobe NAA. Primary causes of intersite differences were attributed to shim quality, B0 drift, and accuracy of RF excitation. Correlation coefficients for measurements at each site were over 0.60, indicating good reliability. A volumetric intensity-normalized MRSI acquisition can be implemented in a comparable manner across multivendor MR instruments. © 2014 Wiley Periodicals, Inc.

A spectroscopic search for colliding stellar winds in O-type close binary systems. I - AO Cassiopeiae

NASA Technical Reports Server (NTRS)

Gies, Douglas R.; Wiggs, Michael S.

1991-01-01

AO Cas, a short-period, double-lined spectroscopic binary, is studied as part of a search for spectroscopic evidence of colliding stellar winds in binary systems of O-type stars. High S/N ratio spectra of the H-alpha and He I 6678-A line profiles are presented, and their orbital-phase-related variations are examined in order to derive the location and motions of high-density circumstellar gas in the system. These profile variations are compared with those observed in the UV stellar wind lines in IUE archival spectra. IUE spectra are also used to derive a system mass ratio by constructing cross-correlation functions of a single-lined phase spectrum with each of the other spectra. The resulting mass ratio is consistent with the rotational line broadening of the primary star, if the primary is rotating synchronously with the binary system. The best-fit models were found to have an inclination of 61.1 deg + or - 3.0 deg and have a primary which is close to filling its critical Roche lobe.

A compact imaging spectroscopic system for biomolecular detections on plasmonic chips.

PubMed

Lo, Shu-Cheng; Lin, En-Hung; Wei, Pei-Kuen; Tsai, Wan-Shao

2016-10-17

In this study, we demonstrate a compact imaging spectroscopic system for high-throughput detection of biomolecular interactions on plasmonic chips, based on a curved grating as the key element of light diffraction and light focusing. Both the curved grating and the plasmonic chips are fabricated on flexible plastic substrates using a gas-assisted thermal-embossing method. A fiber-coupled broadband light source and a camera are included in the system. Spectral resolution within 1 nm is achieved in sensing environmental index solutions and protein bindings. The detected sensitivities of the plasmonic chip are comparable with a commercial spectrometer. An extra one-dimensional scanning stage enables high-throughput detection of protein binding on a designed plasmonic chip consisting of several nanoslit arrays with different periods. The detected resonance wavelengths match well with the grating equation under an air environment. Wavelength shifts between 1 and 9 nm are detected for antigens of various concentrations binding with antibodies. A simple, mass-productive and cost-effective method has been demonstrated on the imaging spectroscopic system for real-time, label-free, highly sensitive and high-throughput screening of biomolecular interactions.

Spectroscopic profiling and computational study of the binding of tschimgine: A natural monoterpene derivative, with calf thymus DNA.

PubMed

Khajeh, Masoumeh Ashrafi; Dehghan, Gholamreza; Dastmalchi, Siavoush; Shaghaghi, Masoomeh; Iranshahi, Mehrdad

2018-03-05

DNA is a major target for a number of anticancer substances. Interaction studies between small molecules and DNA are essential for rational drug designing to influence main biological processes and also introducing new probes for the assay of DNA. Tschimgine (TMG) is a monoterpene derivative with anticancer properties. In the present study we tried to elucidate the interaction of TMG with calf thymus DNA (CT-DNA) using different spectroscopic methods. UV-visible absorption spectrophotometry, fluorescence and circular dichroism (CD) spectroscopies as well as molecular docking study revealed formation of complex between TMG and CT-DNA. Binding constant (K b ) between TMG and DNA was 2.27×10 4 M -1 , that is comparable to groove binding agents. The fluorescence spectroscopic data revealed that the quenching mechanism of fluorescence of TMG by CT-DNA is static quenching. Thermodynamic parameters (ΔH<0 and ΔS<0) at different temperatures indicated that van der Waals forces and hydrogen bonds were involved in the binding process of TMG with CT-DNA. Competitive binding assay with methylene blue (MB) and Hoechst 33258 using fluorescence spectroscopy displayed that TMG possibly binds to the minor groove of CT-DNA. These observations were further confirmed by CD spectral analysis, viscosity measurements and molecular docking. Copyright © 2017 Elsevier B.V. All rights reserved.

Impacts of updated spectroscopy on thermal infrared retrievals of methane evaluated with HIPPO data

NASA Astrophysics Data System (ADS)

Alvarado, M. J.; Payne, V. H.; Cady-Pereira, K. E.; Hegarty, J. D.; Kulawik, S. S.; Wecht, K. J.; Worden, J. R.; Pittman, J. V.; Wofsy, S. C.

2014-09-01

Errors in the spectroscopic parameters used in the forward radiative transfer model can introduce altitude-, spatially-, and temporally-dependent biases in trace gas retrievals. For well-mixed trace gases such as methane, where the variability of tropospheric mixing ratios is relatively small, reducing such biases is particularly important. We use aircraft observations from all five missions of the HIAPER Pole-to-Pole Observations (HIPPO) of the Carbon Cycle and Greenhouse Gases Study to evaluate the impact of updates to spectroscopic parameters for methane (CH4), water vapor (H2O), and nitrous oxide (N2O) on thermal infrared retrievals of methane from the NASA Aura Tropospheric Emission Spectrometer (TES). We find that updates to the spectroscopic parameters for CH4 result in a substantially smaller mean bias in the retrieved CH4 when compared with HIPPO observations. After an N2O-based correction, the bias in TES methane upper tropospheric representative values for measurements between 50° S and 50° N decreases from 56.9 to 25.7 ppbv, while the bias in the lower tropospheric representative value increases only slightly (from 27.3 to 28.4 ppbv). For retrievals with less than 1.6 DOFS, the bias is reduced from 26.8 to 4.8 ppbv. We also find that updates to the spectroscopic parameters for N2O reduce the errors in the retrieved N2O profile.

In vivo imaging and characterization of hypoxia-induced neovascularization and tumor invasion.

PubMed

Lungu, Gina F; Li, Meng-Lin; Xie, Xueyi; Wang, Lihong V; Stoica, George

2007-01-01

Hypoxia is a critical event in tumor progression and angiogenesis. Hypoxia can be detected noninvasively by a novel spectroscopic photoacoustic tomography technology (SPAT) and this finding is supported by our molecular biology investigation aimed to elucidate the etiopathogenesis of SPAT detected hypoxia and angiogenesis. The present study provides an integrated approach to define oxygen status (hypoxia) of intracranial tumor xenografts using spectroscopic photoacoustic tomography. Brain tumors can be identified based on their distorted vascular architecture and oxygen saturation (SO2) images. Noninvasive in vivo tumor oxygenation imaging using SPAT is based on the spectroscopic absorption differences between oxyhemoglobin (O2Hb) and deoxyhemoblobin (HHb). Sprague-Dawley rats inoculated intracranially with ENU1564, a carcinogen-induced rat mammary adenocarcinoma cell line, were imaged with SPAT three weeks post inoculation. Proteins important for tumor angiogenesis and invasion were detected in hypoxic brain foci identified by SPAT and were elevated compared with control brain. Immunohistochemistry, Western blotting, and semi-quantitative RT-PCR showed that HIF-1 alpha, VEGF-A, and VEGFR2 (Flk-1) protein and mRNA expression levels were significantly higher (P < 0.05) in brain tumor tissues compared to normal brain. Gelatin zymography and RT-PCR demonstrated the upregulation of MMP-9 in tumor foci compared with brain control. Together these results suggest the critical role of hypoxia in driving tumor angiogenesis and invasion through upregulation of target genes important for these functions. Moreover this report validates our hypothesis that a novel noninvasive technology (SPAT) developed in our laboratory is suitable for detection of tumors, hypoxia, and angiogenesis.

Spectroscopic evidence of α-methylbenzyl radical in the gas phase

NASA Astrophysics Data System (ADS)

Lee, Gi Woo; Ahn, Hyeon Geun; Kim, Tae Kyu; Lee, Sang Kuk

2008-11-01

We report the observation of the spectroscopic evidence of the α-methylbenzyl radical in a corona excited supersonic expansion using a pinhole-type glass nozzle for the first time. The precursors, toluene, ethylbenzene, and isopropylbenzene, seeded in a large amount of inert carrier gas helium, were electrically discharged to produce benzyl-type radicals as a result of the breaking off of a C-H or a C-C bond from the alkyl chain. The vibronic emission spectra, obtained in the visible region from the precursors, were compared to identify the species generated in the corona discharge of the precursors, from which we found the spectroscopic evidence of the α-methylbenzyl radical.

A "First Principles" Potential Energy Surface for Liquid Water from VRT Spectroscopy of Water Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldman, N; Leforestier, C; Saykally, R J

We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface. VRT(ASP-W)III is shown to not only be a model of high ''spectroscopic'' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared to those from ab initio Molecular Dynamics, other potentials of ''spectroscopic'' accuracy, and to experiment. The results herein represent the first time that a ''spectroscopic'' potential surface is able to correctly model condensed phase properties of water.

Making Aggressive Prostate Cancer Quiescent by Abrogating Cholesterol Esterification

DTIC Science & Technology

2016-10-01

team has been assembled , with expertise in spectroscopic imaging & nanomedicine (Dr. J. X. Cheng, PI), biochemistry (Dr. X. Liu, co-PI), and prostate...was approved in 2004 as the first- line cytotoxic chemotherapy owing to a modest increase in overall survival compared to mitoxantrone. Since 2010...interdisciplinary research team has been assembled , with expertise in spectroscopic imaging & nanomedicine (Dr. J. X. Cheng, PI), biochemistry (Dr. X. Liu, co-PI

A new nortriterpenoid and an ergostane-type steroid from the fruiting bodies of the fungus Ganoderma resinaceum.

PubMed

Chen, Xian-Qiang; Chen, Ling-Xiao; Li, Shao-Ping; Zhao, Jing

2017-12-01

One new expoxy nortriterpenoid (1) and one new ergostane-type steroid (2), together with seven known steroids (3-9), were obtained from the fruiting bodies of the fungus Ganoderma resinaceum. The new compounds were elucidated on the basis of extensive spectroscopic data (MS, NMR, IR, and UV) and the known compounds were identified by comparing spectroscopic data with those reported in literature.

(d ,n ) proton-transfer reactions on 9Be, 11B, 13C, N,1514, and 19F and spectroscopic factors at Ed=16 MeV

NASA Astrophysics Data System (ADS)

Febbraro, M.; Becchetti, F. D.; Torres-Isea, R. O.; Riggins, J.; Lawrence, C. C.; Kolata, J. J.; Howard, A. M.

2017-08-01

The (d ,n ) reaction has been studied with targets of 9Be, 11B, 13C, N,1514, and 19F at Ed=16 MeV using a deuterated liquid-scintillator array. Advanced spectral unfolding techniques with accurately measured scintillator response functions were employed to extract neutron energy spectra without the need for long-path neutron time-of-flight. An analysis of the proton-transfer data at forward angles to the ground states of the final nuclei, using finite-range distorted-wave Born approximation analysis with common bound-state, global, and local optical-model parameter sets, yields a set of self-consistent spectroscopic factors. These are compared with the results of several previous time-of-flight measurements, most done many years ago for individual nuclei at lower energy and often analyzed using zero-range transfer codes. In contrast to some of the earlier published data, our data generally compare well with simple shell-model predictions, with little evidence for uniform quenching (reduction from shell-model values) that has previously been reported from analysis of nucleon knock-out reactions. Data for low-lying excited states in 14N from 13C(d ,n ) also is analyzed and spectroscopic information relevant to nuclear astrophysics obtained. A preliminary study of the radioactive ion beam induced reaction 7Be(d ,n ) , E (7Be)=30 MeV was carried out and indicates further improvements are needed for such measurements, which require detection of neutrons with En<2 MeV .

Spectroscopic detections of C III] λ1909 Å at z ≃ 6-7: a new probe of early star-forming galaxies and cosmic reionization

NASA Astrophysics Data System (ADS)

Stark, Daniel P.; Richard, Johan; Charlot, Stéphane; Clément, Benjamin; Ellis, Richard; Siana, Brian; Robertson, Brant; Schenker, Matthew; Gutkin, Julia; Wofford, Aida

2015-06-01

Deep spectroscopic observations of z ≳ 6.5 galaxies have revealed a marked decline with increasing redshift in the detectability of Ly α emission. While this may offer valuable insight into the end of the reionization process, it presents a challenge to the detailed spectroscopic study of bright photometrically-selected distant sources now being found via deep Hubble Space Telescope imaging, and particularly those highly magnified sources viewed through foreground lensing clusters. In this paper, we demonstrate the validity of a new way forward via the detection of an alternative diagnostic line, C III] λ1909 Å, seen in spectroscopic exposures of a star-forming galaxy at zLyα = 6.029. We also report tentative detection of C III] λ1909 Å in a galaxy at zLyα = 7.213. The former 3.3σ detection is based on a 3.5 h XShooter spectrum of a bright (J125 = 25.2) gravitationally-lensed galaxy behind the cluster Abell 383. The latter 2.8σ detection is based on a 4.2 h MOSFIRE spectra of one of the most distant spectroscopically confirmed galaxies, GN-108036, with J140 = 25.2. Both targets were chosen for their continuum brightness and previously-known redshift (based on Ly α), ensuring that any C III] emission would be located in a favourable portion of the near-infrared sky spectrum. Since the availability of secure Ly α redshifts significantly narrows the wavelength range where C III] is sought, this increases confidence in these, otherwise, low-signal-to-noise ratio detections. We compare our C III] and Ly α equivalent widths in the context of those found at z ≃ 2 from earlier work and discuss the motivation for using lines other than Ly α to study galaxies in the reionization era.

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak

2005-07-01

Explosives formulations with Reduced- Sensitivity RDX showed reduced shock sensitivity using NOL Large Scale Gap Test, compared with similar formulations using normal RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light to the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. SIRDX, a form of Reduced- Sensitivity RDX, was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transformed IR (FTIR). The pressure dependence of the Raman mode frequencies of SIRDX was determined and compared with that of normal RDX. The behavior of SIRDX near the pressure at which normal RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph will be presented. Implications to the reduction in sensitivity will be discussed.

Stratospheric HNO3 measurements from 0.002/cm resolution solar occultation spectra and improved spectroscopic line parameters in the 5.8-micron region

NASA Technical Reports Server (NTRS)

Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, D. G.; Rinsland, C. P.; Flaud, J.-M.; Camy-Peyret, C.

1992-01-01

Very-high-resolution FWHM solar-occultation spectra are investigated with a balloon-borne interferometer using revised spectroscopic line parameters for HNO3, O3, and H2O. The O3 and H2O data are evaluated to determine their capacity for interference in the HNO3 line which is studied in the nu sub 2 band at 5.8 microns. The line parameters developed with the stratospheric data are compared to data based on a HITRAN compilation as well as laboratory spectra with a 0.002/cm resolution. The line list is calculated and shown to include J and Ka transitions which improve the line parameters for HNO3 by accounting for the weaker absorption features in the stratospheric spectra. The stratospheric HNO3 profile developed analytically is compared to those based on reported measurements, and the one developed with the stratospheric solar spectra is found to be consistent with the measurements and confirm inherent measurement biases.

The Dynamic Atmospheres of Carbon Rich Giants: Constraining Models Via Interferometry

NASA Astrophysics Data System (ADS)

Rau, Gioia; Hron, Josef; Paladini, Claudia; Aringer, Bernard; Eriksson, Kjell; Marigo, Paola

2016-07-01

Dynamic models for the atmospheres of C-rich Asymptotic Giant Branch stars are quite advanced and have been overall successful in reproducing spectroscopic and photometric observations. Interferometry provides independent information and is thus an important technique to study the atmospheric stratification and to further constrain the dynamic models. We observed a sample of six C-rich AGBs with the mid infrared interferometer VLTI/MIDI. These observations, combined with photometric and spectroscopic data from the literature, are compared with synthetic observables derived from dynamic model atmospheres (DMA, Eriksson et al. 2014). The SEDs can be reasonably well modelled and the interferometry supports the extended and multi-component structure of the atmospheres, but some differences remain. We discuss the possible reasons for these differences and we compare the stellar parameters derived from this comparison with stellar evolution models. Finally, we point out the high potential of MATISSE, the second generation VLTI instrument allowing interferometric imaging in the L, M, and N bands, for further progress in this field.

1-Amino-4-hydroxy-9,10-anthraquinone - An analogue of anthracycline anticancer drugs, interacts with DNA and induces apoptosis in human MDA-MB-231 breast adinocarcinoma cells: Evaluation of structure-activity relationship using computational, spectroscopic and biochemical studies.

PubMed

Mondal, Palash; Roy, Sanjay; Loganathan, Gayathri; Mandal, Bitapi; Dharumadurai, Dhanasekaran; Akbarsha, Mohammad A; Sengupta, Partha Sarathi; Chattopadhyay, Shouvik; Guin, Partha Sarathi

2015-12-01

The X-ray diffraction and spectroscopic properties of 1-amino-4-hydroxy-9,10-anthraquinone (1-AHAQ), a simple analogue of anthracycline chemotherapeutic drugs were studied by adopting experimental and computational methods. The optimized geometrical parameters obtained from computational methods were compared with the results of X-ray diffraction analysis and the two were found to be in reasonably good agreement. X-ray diffraction study, Density Functional Theory (DFT) and natural bond orbital (NBO) analysis indicated two types of hydrogen bonds in the molecule. The IR spectra of 1-AHAQ were studied by Vibrational Energy Distribution Analysis (VEDA) using potential energy distribution (PED) analysis. The electronic spectra were studied by TDDFT computation and compared with the experimental results. Experimental and theoretical results corroborated each other to a fair extent. To understand the biological efficacy of 1-AHAQ, it was allowed to interact with calf thymus DNA and human breast adino-carcinoma cell MDA-MB-231. It was found that the molecule induces apoptosis in this adinocarcinoma cell, with little, if any, cytotoxic effect in HBL-100 normal breast epithelial cell.

Improving 1H MRSI measurement of cerebral lactate for clinical applications

PubMed Central

Corrigan, Neva M.; Richards, Todd L.; Friedman, Seth D.; Petropoulos, Helen; Dager, Stephen R.

2010-01-01

Accurate measurement of cerebral lactate is critical to the understanding of brain function for psychiatric disorders such as panic disorder and bipolar disorder as well as mitochondrial dysfunction. Proton magnetic spectroscopic imaging (MRSI) techniques can be used to study lactate in vivo; however, accurate measurement of cerebral lactate, which is normally at low basal abundance, can be challenging. In this study, regional lactate measurements obtained with two different MRSI analytic approaches were evaluated using proton echo-planar spectroscopic imaging (PEPSI) data from 18 healthy adults participating in an in vivo sodium lactate infusion study. The results demonstrate that averaging data within a region of interest (ROI) before spectral fitting with LCModel results in significantly improved lactate measurement as compared to averaging chemical concentrations derived from the fitting of individual voxels in the ROI. Simulation results that confirm this finding are also presented. This study additionally outlines an atlas-based approach for the systematic computation of regional distributions of chemical concentrations in large MRSI data sets. PMID:20236806

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

NASA Astrophysics Data System (ADS)

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

2015-03-01

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

Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowińska, Małgorzata, E-mail: malgorzata.sowinska@b-tu.de; Henkel, Karsten; Schmeißer, Dieter

2016-01-15

The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiO{sub x}N{sub y}) films was studied. Titanium(IV)isopropoxide in combination with NH{sub 3} plasma and tetrakis(dimethylamino)titanium by applying N{sub 2} plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiO{sub x}N{sub y} films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film propertiesmore » can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.« less

Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

PubMed

Singh, Gurpreet; Mohanty, B P; Saini, G S S

2016-02-15

Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation of the COROT mission: fundamental stellar parameters from photometric and spectroscopic analyses of target candidates

NASA Astrophysics Data System (ADS)

Lastennet, E.; Lignières, F.; Buser, R.; Lejeune, T.; Lüftinger, T.; Cuisinier, F.; van't Veer-Menneret, C.

2001-09-01

We present a sample of 9 nearby F-type stars with detailed spectroscopic analyses to investigate the Basel Stellar Library (BaSeL) in two photometric systems simultaneously, Johnson UBV and Stromgren uvby. The sample corresponds to potential targets of the central seismology programme of the COROT (COnvection & ROtation) space experiment, which have been recently observed at Observatoire de Haute-Provence (OHP, France). The atmospheric parameters Teff, [Fe/H], and log g obtained from the BaSeL models are compared with spectroscopic determinations as well as with results of other photometric calibrations (the TEMPLOGG method and the catalogue of Marsakov & Shevelev, 1995). Moreover, new rotational velocity determinations are also derived from the spectroscopic analysis and compared with previous results compiled in the SIMBAD database. For a careful interpretation of the BaSeL solutions, we computed confidence regions around the best chi^2-estimates and projected them on Teff-[Fe/H], Teff-log g, and log g-[Fe/H] diagrams. In order to simultaneously and accurately determine the stellar parameters Teff, [Fe/H] and log g, we suggest to use the combination of the synthetic BaSeL indices B-V, U-B and b-y (rather than the full photometric information available for these stars: B-V, U-B, b-y, m1 and c1) and we present complete results in 3 different diagrams, along with the results of other methods (photometric and spectroscopic). All the methods presented give consistent solutions, and the agreement between TEMPLOGG and BaSeL for the hottest stars of the sample could be especially useful in view of the well-known difficulty of spectroscopic determinations for fast rotating stars. Finally, we present current and future developments of the BaSeL models for a systematic application to all the COROT targets.

Preparation of the COROT mission: fundamental stellar parameters from photometric and spectroscopic analyses of target candidates

NASA Astrophysics Data System (ADS)

Lastennet, E.; Lignières, F.; Buser, R.; Lejeune, T.; Lüftinger, T.; Cuisinier, F.; van't Veer-Menneret, C.

2001-12-01

We present a sample of 9 nearby F-type stars with detailed spectroscopic analyses to investigate the Basel Stellar Library (BaSeL) in two photometric systems simultaneously, Johnson UBV and Strömgren uvby. The sample corresponds to potential targets of the central seismology programme of the COROT (COnvection & ROtation) space experiment, which have been recently observed at Observatoire de Haute-Provence (OHP, France). The atmospheric parameters Teff, [Fe/H], and log g obtained from the BaSeL models are compared with spectroscopic determinations as well as with results of other photometric calibrations (the TEMPLOGG method and the catalogue of Marsakov & Shevelev, 1995). Moreover, new rotational velocity determinations are also derived from the spectroscopic analysis and compared with previous results compiled in the SIMBAD database. For a careful interpretation of the BaSeL solutions, we computed confidence regions around the best χ2-estimates and projected them on Teff-[Fe/H], Teff-log g, and log g-[Fe/H] diagrams. In order to simultaneously and accurately determine the stellar parameters Teff, [Fe/H] and log g, we suggest to use the combination of the synthetic BaSeL indices B-V, U-B and b-y (rather than the full photometric information available for these stars: B-V, U-B, b-y, m1 and c1) and we present complete results in 3 different diagrams, along with the results of other methods (photometric and spectroscopic). All the methods presented give consistent solutions, and the agreement between TEMPLOGG and BaSeL for the hottest stars of the sample could be especially useful in view of the well-known difficulty of spectroscopic determinations for fast rotating stars. Finally, we present current and future developments of the BaSeL models for a systematic application to all the COROT targets.

Testing the white dwarf mass-radius relation and comparing optical and far-UV spectroscopic results with Gaia DR2, HST and FUSE

NASA Astrophysics Data System (ADS)

Joyce, S. R. G.; Barstow, M. A.; Casewell, S. L.; Burleigh, M. R.; Holberg, J. B.; Bond, H. E.

2018-05-01

Observational tests of the white dwarf mass-radius relationship have always been limited by the uncertainty in the available distance measurements. Most studies have focused on Balmer line spectroscopy because these spectra can be obtained from ground based observatories, while the Lyman lines are only accessible to space based UV telescopes. We present results using parallax data from Gaia DR2 combined with space based spectroscopy from HST and FUSE covering the Balmer and Lyman lines. We find that our sample supports the theoretical relation, although there is at least one star which is shown to be inconsistent. Comparison of results between Balmer and Lyman line spectra shows they are in agreement when the latest broadening tables are used. We also assess the factors which contribute to the error in the mass-radius calculations and confirm the findings of other studies which show that the spread in results for targets where multiple spectra are available is larger than the statistical error. The uncertainty in the spectroscopically derived log g parameter is now the main source of error rather than the parallax. Finally, we present new results for the radius and spectroscopic mass of Sirius B which agree with the dynamical mass and mass-radius relation within 1σ.

Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

NASA Technical Reports Server (NTRS)

Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

1992-01-01

The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

Structural and vibrational spectroscopy investigation of the 5-[(diphenyl) amino] isophthalic acid molecule

NASA Astrophysics Data System (ADS)

Kurt, M.; Şaş, E. Babur; Can, M.; Okur, S.; Icli, S.; Demic, S.

2014-10-01

The molecular structure and vibrations of 5-(diphenyl) amino] isophthalic acid (DPIFA) were investigated by different spectroscopic techniques (such as infrared and Raman). FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. HOMO-LUMO analyses were performed. The theoretical calculations for the molecular structure and spectroscopic studies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After optimizing the geometry of the molecule, vibration wavenumbers and fundamental vibrations wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra.

A newly synthesized thiazole derivative as a fluoride ion chemosensor: naked-eye, spectroscopic, electrochemical and NMR studies.

PubMed

Sarıgüney, Ahmet Burak; Saf, Ahmet Özgür; Coşkun, Ahmet

2014-07-15

2,3-Indoledione 3-thiosemicarbazone (TSCI) and a novel compound 3-(2-(4-(4-phenoxyphenyl)thiazol-2-yl)hydrazono)indolin-2-one (FTHI) were synthesized with high yield and characterized by spectroscopic techniques. The complexation behaviors of TSCI and FTHI for various anionic species (F(-), Cl(-), Br(-), I(-), NO2(-), NO3(-), BzO(-), HSO4(-), ClO4(-)) in CH3CN were investigated and compared by UV-vis spectroscopy, cyclic voltammetry and (1)H NMR titration techniques. FTHI showed high degree of selectivity for fluoride over other anions. This selectivity could be easily observed by the naked eye, indicating that FTHI is potential colorimetric sensor for fluoride anion. Copyright © 2014 Elsevier B.V. All rights reserved.

Galaxy Merger Candidates in High-redshift Cluster Environments

NASA Astrophysics Data System (ADS)

Delahaye, A. G.; Webb, T. M. A.; Nantais, J.; DeGroot, A.; Wilson, G.; Muzzin, A.; Yee, H. K. C.; Foltz, R.; Noble, A. G.; Demarco, R.; Tudorica, A.; Cooper, M. C.; Lidman, C.; Perlmutter, S.; Hayden, B.; Boone, K.; Surace, J.

2017-07-01

We compile a sample of spectroscopically and photometrically selected cluster galaxies from four high-redshift galaxy clusters (1.59< z< 1.71) from the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS), and a comparison field sample selected from the UKIDSS Deep Survey. Using near-infrared imaging from the Hubble Space Telescope, we classify potential mergers involving massive ({M}* ≥slant 3× {10}10 {M}⊙ ) cluster members by eye, based on morphological properties such as tidal distortions, double nuclei, and projected near neighbors within 20 kpc. With a catalog of 23 spectroscopic and 32 photometric massive cluster members across the four clusters and 65 spectroscopic and 26 photometric comparable field galaxies, we find that after taking into account contamination from interlopers, {11.0}-5.6+7.0 % of the cluster members are involved in potential mergers, compared to {24.7}-4.6+5.3 % of the field galaxies. We see no evidence of merger enhancement in the central cluster environment with respect to the field, suggesting that galaxy-galaxy merging is not a stronger source of galaxy evolution in cluster environments compared to the field at these redshifts.

Impact of the differential fluence distribution of brachytherapy sources on the spectroscopic dose-rate constant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malin, Martha J.; Bartol, Laura J.; DeWerd, Larry A., E-mail: mmalin@wisc.edu, E-mail: ladewerd@wisc.edu

2015-05-15

Purpose: To investigate why dose-rate constants for {sup 125}I and {sup 103}Pd seeds computed using the spectroscopic technique, Λ{sub spec}, differ from those computed with standard Monte Carlo (MC) techniques. A potential cause of these discrepancies is the spectroscopic technique’s use of approximations of the true fluence distribution leaving the source, φ{sub full}. In particular, the fluence distribution used in the spectroscopic technique, φ{sub spec}, approximates the spatial, angular, and energy distributions of φ{sub full}. This work quantified the extent to which each of these approximations affects the accuracy of Λ{sub spec}. Additionally, this study investigated how the simplified water-onlymore » model used in the spectroscopic technique impacts the accuracy of Λ{sub spec}. Methods: Dose-rate constants as described in the AAPM TG-43U1 report, Λ{sub full}, were computed with MC simulations using the full source geometry for each of 14 different {sup 125}I and 6 different {sup 103}Pd source models. In addition, the spectrum emitted along the perpendicular bisector of each source was simulated in vacuum using the full source model and used to compute Λ{sub spec}. Λ{sub spec} was compared to Λ{sub full} to verify the discrepancy reported by Rodriguez and Rogers. Using MC simulations, a phase space of the fluence leaving the encapsulation of each full source model was created. The spatial and angular distributions of φ{sub full} were extracted from the phase spaces and were qualitatively compared to those used by φ{sub spec}. Additionally, each phase space was modified to reflect one of the approximated distributions (spatial, angular, or energy) used by φ{sub spec}. The dose-rate constant resulting from using approximated distribution i, Λ{sub approx,i}, was computed using the modified phase space and compared to Λ{sub full}. For each source, this process was repeated for each approximation in order to determine which approximations used in the spectroscopic technique affect the accuracy of Λ{sub spec}. Results: For all sources studied, the angular and spatial distributions of φ{sub full} were more complex than the distributions used in φ{sub spec}. Differences between Λ{sub spec} and Λ{sub full} ranged from −0.6% to +6.4%, confirming the discrepancies found by Rodriguez and Rogers. The largest contribution to the discrepancy was the assumption of isotropic emission in φ{sub spec}, which caused differences in Λ of up to +5.3% relative to Λ{sub full}. Use of the approximated spatial and energy distributions caused smaller average discrepancies in Λ of −0.4% and +0.1%, respectively. The water-only model introduced an average discrepancy in Λ of −0.4%. Conclusions: The approximations used in φ{sub spec} caused discrepancies between Λ{sub approx,i} and Λ{sub full} of up to 7.8%. With the exception of the energy distribution, the approximations used in φ{sub spec} contributed to this discrepancy for all source models studied. To improve the accuracy of Λ{sub spec}, the spatial and angular distributions of φ{sub full} could be measured, with the measurements replacing the approximated distributions. The methodology used in this work could be used to determine the resolution that such measurements would require by computing the dose-rate constants from phase spaces modified to reflect φ{sub full} binned at different spatial and angular resolutions.« less

Hydrogen bonding interactions in nicotinamide Ionic Liquids: A comparative spectroscopic and DFT studies

NASA Astrophysics Data System (ADS)

Shukla, Madhulata

2017-03-01

Being biodegradable in nature nicotinamide based Ionic Liquids (ILs) are gaining much attention now a day. Nicotinamide iodide (i.e 1-methyl-3ethoxy carbonyl pyridinium iodide (mNicI)) and 1-methyl-3ethoxy carbonyl pyridinium trifilimide (mNicNTf2) new ILs has been synthesized and has been characterized using different spectroscopic techniques like NMR, UV visible and infrared spectroscopy. Theoretical studies have been performed on several nicotinamide ILs. Geometry and spectral features were further characterized by Density Functional Theory (DFT) calculation. NBO charge distribution and electrostatic potential diagram presents in depth knowledge about interactions between cation and anion. A comparative theoretical study between mNicI and its other analogues i. e 1-methyl-3 ethoxy carbonyl pyridinium chloride and bromide i. e mNicCl and mNicBr has also been performed. Csbnd H⋯X hydrogen bonding along with C⋯X interaction has been reported for the first time for the nicotinamide based ILs. C2sbnd H stretching frequency shifts to higher wavenumber with change to a lesser electronegative anion. mNicCl and mNicBr are expected to be solid in nature with the evidence from the red shift in stretching frequency as compared to mNicI. TD-DFT calculation of mNicI proved that pale yellow color of liquid is due to inherent transition from anion to cation.

Kepler Flares. IV. A Comprehensive Analysis of the Activity of the dM4e Star GJ 1243

NASA Astrophysics Data System (ADS)

Silverberg, Steven M.; Kowalski, Adam F.; Davenport, James R. A.; Wisniewski, John P.; Hawley, Suzanne L.; Hilton, Eric J.

2016-10-01

We present a comprehensive study of the active dM4e star GJ 1243. We use previous observations and ground-based echelle spectroscopy to determine that GJ 1243 is a member of the Argus association of field stars, suggesting it is ∼ 30{--}50 {{Myr}} old. We analyze 11 months of 1 minute cadence data from Kepler, presenting Kepler flare frequency distributions, as well as determining correlations between flare energy, amplitude, duration, and decay time. We find that the exponent α of the power-law flare energy distribution varies in time, primarily due to completeness of sample and the low frequency of high-energy flares. We also find a deviation from a single power law at high energy. We use ground-based spectroscopic observations that were simultaneous with the Kepler data to provide simultaneous photometric and spectroscopic analysis of three low-energy flares, the lowest-energy dMe flares with detailed spectral analysis to date on any star. The spectroscopic data from these flares extend constraints for radiative hydrodynamic flare models to a lower energy regime than has previously been studied. We use this simultaneous spectroscopy and Kepler photometry to develop approximate conversions from the Kepler bandpass to the traditional U and B bands. This conversion will be a critical factor in comparing any Kepler flare analyses to the canon of previous ground-based flare studies.

Spectroscopic properties for identifying sapphire samples from Ban Bo Kaew, Phrae Province, Thailand

NASA Astrophysics Data System (ADS)

Mogmued, J.; Monarumit, N.; Won-in, K.; Satitkune, S.

2017-09-01

Gemstone commercial is a high revenue for Thailand especially ruby and sapphire. Moreover, Phrae is a potential gem field located in the northern part of Thailand. The studies of spectroscopic properties are mainly to identify gemstone using advanced techniques (e.g. UV-Vis-NIR spectrophotometry, FTIR spectrometry and Raman spectroscopy). Typically, UV-Vis-NIR spectrophotometry is a technique to study the cause of color in gemstones. FTIR spectrometry is a technique to study the functional groups in gem-materials. Raman pattern can be applied to identify the mineral inclusions in gemstones. In this study, the natural sapphires from Ban Bo Kaew were divided into two groups based on colors including blue and green. The samples were analyzed by UV-Vis-NIR spectrophotometer, FTIR spectrometer and Raman spectroscope for studying spectroscopic properties. According to UV-Vis-NIR spectra, the blue sapphires show higher Fe3+/Ti4+ and Fe2+/Fe3+ absorption peaks than those of green sapphires. Otherwise, green sapphires display higher Fe3+/Fe3+ absorption peaks than blue sapphires. The FTIR spectra of both blue and green sapphire samples show the absorption peaks of -OH,-CH and CO2. The mineral inclusions such as ferrocolumbite and rutile in sapphires from this area were observed by Raman spectroscope. The spectroscopic properties of sapphire samples from Ban Bo Kaew, Phrae Province, Thailand are applied to be the specific evidence for gemstone identification.

PRISM: Processing routines in IDL for spectroscopic measurements (installation manual and user's guide, version 1.0)

USGS Publications Warehouse

Kokaly, Raymond F.

2011-01-01

This report describes procedures for installing and using the U.S. Geological Survey Processing Routines in IDL for Spectroscopic Measurements (PRISM) software. PRISM provides a framework to conduct spectroscopic analysis of measurements made using laboratory, field, airborne, and space-based spectrometers. Using PRISM functions, the user can compare the spectra of materials of unknown composition with reference spectra of known materials. This spectroscopic analysis allows the composition of the material to be identified and characterized. Among its other functions, PRISM contains routines for the storage of spectra in database files, import/export of ENVI spectral libraries, importation of field spectra, correction of spectra to absolute reflectance, arithmetic operations on spectra, interactive continuum removal and comparison of spectral features, correction of imaging spectrometer data to ground-calibrated reflectance, and identification and mapping of materials using spectral feature-based analysis of reflectance data. This report provides step-by-step instructions for installing the PRISM software and running its functions.

Spectroscopic and Interferometric Measurements of Nine K Giant Stars

NASA Astrophysics Data System (ADS)

Baines, Ellyn K.; Döllinger, Michaela P.; Guenther, Eike W.; Hatzes, Artie P.; Hrudkovu, Marie; van Belle, Gerard T.

2016-09-01

We present spectroscopic and interferometric measurements for a sample of nine K giant stars. These targets are of particular interest because they are slated for stellar oscillation observations. Our improved parameters will directly translate into reduced errors in the final masses for these stars when interferometric radii and asteroseismic densities are combined. Here, we determine each star’s limb-darkened angular diameter, physical radius, luminosity, bolometric flux, effective temperature, surface gravity, metallicity, and mass. When we compare our interferometric and spectroscopic results, we find no systematic offsets in the diameters and the values generally agree within the errors. Our interferometric temperatures for seven of the nine stars are hotter than those determined from spectroscopy with an average difference of about 380 K.

Ultrasonic promoted synthesis of novel s-triazine-Schiff base derivatives; molecular structure, spectroscopic studies and their preliminary anti-proliferative activities

NASA Astrophysics Data System (ADS)

El-Faham, Ayman; Soliman, Saied M.; Ghabbour, Hazem A.; Elnakady, Yasser A.; Mohaya, Talal A.; Siddiqui, Mohammed R. H.; Albericio, Fernando

2016-12-01

Novel series of s-triazine-Schiff base derivatives were synthesized employing ultrasonic irradiation and characterized by NMR (1H and 13C), FT-IR, and elemental analysis. The use of ultrasonic irradiation has allowed the preparation of the target products with better yields in shorter reaction time and excellent purities compared to the conventional heating. X-ray single crystal diffraction experiments verified the molecular structure of four from the new prepared s-triaizne-Schiff base derivatives. The molecular structures of the studied compounds are computerized using DFT/B3LYP method. The effects of substituent at the triazine and phenyl ring on the electronic and spectroscopic properties of the studied compounds were also investigated. The natural atomic charges showed that pipridino-s-triazine derivatives are richer in electrons than those having morpholino derivatives. The anti-proliferative effects for the prepared compounds were tested against three different cancer cell lines.

Polarimetric scattering behavior of materials at terahertz frequencies

NASA Astrophysics Data System (ADS)

DiGiovanni, David Anthony

Terahertz spectroscopic techniques have long been used to characterize the electromagnetic behavior of materials for use in radar, astronomy, and remote sensing applications. Spectroscopic information is valuable, but additional information about materials is present in the polarization of the scattered radiation. This thesis has investigated the polarimetric scattering behavior of various rough dielectric and metallic materials from 100 GHz to 1.55 THz. Common building materials and terrain, such as sand, gravel, soil, concrete, and roofing shingles, were studied. In order to obtain a better understanding of basic rough surface scattering phenomenology in this region of the spectrum, roughened metal and plastic samples were studied as well. The scattering behavior of these materials was studied as a function of incident angle, roughness, frequency, and polarization. Theoretical scattering models were used to compare measured results to theoretical predictions. Good agreement was observed between scattering measurements and theoretical predictions based on the small perturbation theory for the roughened metal surfaces. However, a substantial disagreement was observed for the rough dielectric surfaces and is discussed.

Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy)

NASA Astrophysics Data System (ADS)

De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M.; Miriello, Domenico

2016-01-01

This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

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).

Probing of O2 vacancy defects and correlated magnetic, electrical and photoresponse properties in indium-tin oxide nanostructures by spectroscopic techniques

NASA Astrophysics Data System (ADS)

Ghosh, Shyamsundar; Dev, Bhupendra Nath

2018-05-01

Indium-tin oxide (ITO) 1D nanostructures with tunable morphologies i.e. nanorods, nanocombs and nanowires are grown on c-axis (0 0 0 1) sapphire (Al2O3) substrate in oxygen deficient atmosphere through pulsed laser deposition (PLD) technique and the effect of oxygen vacancies on optical, electrical, magnetic and photoresponse properties is investigated using spectroscopic methods. ITO nanostructures are found to be enriched with significant oxygen vacancy defects as evident from X-ray photoelectron and Raman spectroscopic analysis. Photoluminescence spectra exhibited intense mid-band blue emission at wavelength of region of 400-450 nm due to the electronic transition from conduction band maxima (CBM) to the singly ionized oxygen-vacancy (VO+) defect level within the band-gap. Interestingly, ITO nanostructures exhibited significant room-temperature ferromagnetism (RTFM) and the magnetic moment found proportional to concentration of VO+ defects which indicates VO+ defects are mainly responsible for the observed RTFM in nanostructures. ITO nanowires being enriched with more VO+ defects exhibited strongest RTFM as compared to other morphologies. Current voltage (I-V) characteristics of ITO nanostructures showed an enhancement of current under UV light as compared to dark which indicates such 1D nanostructure can be used as photovoltaic material. Hence, the study shows that there is ample opportunity to tailor the properties of ITOs through proper defect engineering's and such photosensitive ferromagnetic semiconductors might be promising for spintronic and photovoltaic applications.

A Comparative Study of the Influence of Sugars Sucrose, Trehalose, and Maltose on the Hydration and Diffusion of DMPC Lipid Bilayer at Complete Hydration: Investigation of Structural and Spectroscopic Aspect of Lipid-Sugar Interaction.

PubMed

Roy, Arpita; Dutta, Rupam; Kundu, Niloy; Banik, Debasis; Sarkar, Nilmoni

2016-05-24

It is well-known that sugars protect membrane structures against fusion and leakage. Here, we have investigated the interaction between different sugars (sucrose, trehalose, and maltose) and phospholipid membrane of 1,2-dimyristoyl-sn-glycero-3-phoshpocholine (DMPC) using dynamic light scattering (DLS), transmission electron microscopy (TEM), and other various spectroscopic techniques. DLS measurement reveals that the addition of sugar molecule results a significant increase of the average diameter of DMPC membrane. We have also noticed that in the presence of different sugars the rotational relaxation and solvation time of coumarin 480 (C480) and coumarin 153 (C153) surrounding DMPC membrane increases, suggesting a marked reduction of the hydration behavior at the surface of phospholipid membrane. In addition, we have also investigated the effect of sugar molecules on the lateral mobility of phospholipids. Interestingly, the relative increase in rotational, solvation and lateral diffusion is more prominent for C480 than that of C153 because of their different location in lipid bilayer. It is because of preferential location of comparatively hydrophilic probe C480 in the interfacial region of the lipid bilayer. Sugars intercalate with the phospholipid headgroup through hydrogen bonding and replace smaller sized water molecules from the membrane surface. Therefore, overall, we have monitored a comparative analysis regarding the interaction of different sugar molecules (sucrose, trehalose, and maltose) with the DMPC membrane through DLS, TEM, solvation dynamics, time-resolved anisotropy, and fluorescence correlation spectroscopy (FCS) measurements to explore the structural and spectroscopic aspect of lipid-sugar interaction.

Impacts of updated spectroscopy on thermal infrared retrievals of methane evaluated with HIPPO data

NASA Astrophysics Data System (ADS)

Alvarado, M. J.; Payne, V. H.; Cady-Pereira, K. E.; Hegarty, J. D.; Kulawik, S. S.; Wecht, K. J.; Worden, J. R.; Pittman, J. V.; Wofsy, S. C.

2015-02-01

Errors in the spectroscopic parameters used in the forward radiative transfer model can introduce spatially, temporally, and altitude-dependent biases in trace gas retrievals. For well-mixed trace gases such as methane, where the variability of tropospheric mixing ratios is relatively small, reducing such biases is particularly important. We use aircraft observations from all five missions of the HIAPER Pole-to-Pole Observations (HIPPO) of the Carbon Cycle and Greenhouse Gases Study to evaluate the impact of updates to spectroscopic parameters for methane (CH4), water vapor (H2O), and nitrous oxide (N2O) on thermal infrared retrievals of methane from the NASA Aura Tropospheric Emission Spectrometer (TES). We find that updates to the spectroscopic parameters for CH4 result in a substantially smaller mean bias in the retrieved CH4 when compared with HIPPO observations. After an N2O-based correction, the bias in TES methane upper tropospheric representative values for measurements between 50° S and 50° N decreases from 56.9 to 25.7 ppbv, while the bias in the lower tropospheric representative value increases only slightly (from 27.3 to 28.4 ppbv). For retrievals with less than 1.6 degrees of freedom for signal (DOFS), the bias is reduced from 26.8 to 4.8 ppbv. We also find that updates to the spectroscopic parameters for N2O reduce the errors in the retrieved N2O profile.

Accelerated short-TE 3D proton echo-planar spectroscopic imaging using 2D-SENSE with a 32-channel array coil.

PubMed

Otazo, Ricardo; Tsai, Shang-Yueh; Lin, Fa-Hsuan; Posse, Stefan

2007-12-01

MR spectroscopic imaging (MRSI) with whole brain coverage in clinically feasible acquisition times still remains a major challenge. A combination of MRSI with parallel imaging has shown promise to reduce the long encoding times and 2D acceleration with a large array coil is expected to provide high acceleration capability. In this work a very high-speed method for 3D-MRSI based on the combination of proton echo planar spectroscopic imaging (PEPSI) with regularized 2D-SENSE reconstruction is developed. Regularization was performed by constraining the singular value decomposition of the encoding matrix to reduce the effect of low-value and overlapped coil sensitivities. The effects of spectral heterogeneity and discontinuities in coil sensitivity across the spectroscopic voxels were minimized by unaliasing the point spread function. As a result the contamination from extracranial lipids was reduced 1.6-fold on average compared to standard SENSE. We show that the acquisition of short-TE (15 ms) 3D-PEPSI at 3 T with a 32 x 32 x 8 spatial matrix using a 32-channel array coil can be accelerated 8-fold (R = 4 x 2) along y-z to achieve a minimum acquisition time of 1 min. Maps of the concentrations of N-acetyl-aspartate, creatine, choline, and glutamate were obtained with moderate reduction in spatial-spectral quality. The short acquisition time makes the method suitable for volumetric metabolite mapping in clinical studies. (c) 2007 Wiley-Liss, Inc.

Spectroscopic and laser properties of Er{sup 3+} doped fluoro-phosphate glasses as promising candidates for broadband optical fiber lasers and amplifiers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, S.; Seshadri, M.; Reddy Prasad, V.

2015-10-15

Highlights: • Erbium doped different fluoro-phosphate glasses are prepared and characterized. • Spectroscopic properties have been determined using Judd–Ofelt and Mc-Cumber theory. • Prominent laser transition Er{sup 3+}:{sup 4}I{sub 13/2} → {sup 4}I{sub 15/2} is observed at 1.53 μm. - Abstract: Different fluoro-phosphate glasses doped with 0.5 mol% Er{sup 3+} doped are prepared by melt quenching method. Both structural and spectroscopic properties have been characterized in order to evaluate their potential as both laser source and amplifier materials. Optical absorption measurements are carried out and analyzed through Judd–Ofelt and Mc-Cumber theories where spectroscopic parameters such as intensity parameters Ω{sub l}more » (λ = 2,4,6), transition probabilities, radiative lifetimes, stimulated absorption cross-sections and emission cross-sections at 1.5 μm have been evaluated for Er{sup 3+} doped different fluorophosphate glasses. The various luminescence and gain properties are explained from photoluminescence studies. The decay curve analysis have been done for obtaining the decay time constants of Er{sup 3+} excited level {sup 4}I{sub 13/2} in all the fluoro-phosphate glasses. The obtained results of each glass matrix are compared with the equivalent parameters for several other host glasses. These fluoro-phosphate glasses are found to be suitable candidates for laser and amplifier applications.« less

Molecular structure, spectroscopic studies, and coppersbnd oxygen bond strength of α-methyl and α-ethyl derivatives of copper (II) acetylacetonate; Experimental and theoretical approach

NASA Astrophysics Data System (ADS)

Seyedkatouli, Seyedabdollah; Vakili, Mohammad; Tayyari, Sayyed Faramarz; Afzali, Raheleh

2018-05-01

This paper presents a combined experimental and theoretical study on the Cusbnd O bond strength of copper (II) α-methylacetylacetonate, Cu(3-Meacac)2, and copper (II) α-ethylacetylacetonate, Cu(3-Etacac)2, complexes in comparison to that in copper (II) acetylacetonate, Cu(acac)2. For this purpose, the molecular structure, UV spectra, and complete vibrational assignment of target molecules were investigated by DFT, Natural Bond Orbital (NBO) theory, and Atoms-in-Molecules (AIM) analysis at the B3LYP/6-311G* level of theory. The mentioned results are compared with those in Cu(acac)2. Fourier transform-Raman, IR, and UV spectra of these complexes have been also recorded. A complete assignment of the observed band frequencies has been done. All theoretical and experimental spectroscopic results are consisting with a stronger metal-oxygen bond in Cu(3-Meacac)2 and Cu(3-Etacac)2 complexes compared with Cu(acac)2. In addition, these results confirm that there is no significant difference between the Cusbnd O bond strength of the Cu(3-Meacac)2 and Cu(3-Etacac)2 complexes.

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

PubMed

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

2015-02-25

Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular O-H⋯N interactions in salicylaldehyde derivatives between the O-H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory. Copyright © 2014 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2014-09-01

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

Laboratory spectroscopy and astronomical significance of the fully-benzenoid PAH triphenylene and its cation

NASA Astrophysics Data System (ADS)

Kofman, V.; Sarre, P. J.; Hibbins, R. E.; ten Kate, I. L.; Linnartz, H.

2017-06-01

Triphenylene (C18H12) is a highly symmetric polycyclic aromatic hydrocarbon (PAH) molecule with a 'fully-benzenoid' electronic structure. This confers a high chemical stability compared with PAHs of similar size. Although numerous infrared and UV-vis experimental spectroscopic and theoretical studies of a wide range PAHs in an astrophysical context have been conducted, triphenylene and its radical cation have received almost no attention. There exists a huge body of spectroscopic evidence for neutral and ionised PAHs in astrophysical sources, obtained principally through detection of infrared emission features that are characteristic of PAHs as a chemical class. However, it has so far not proved possible to identify spectroscopically a single isolated PAH in space, although PAHs including triphenylene have been detected mass spectrometrically in meteorites. In this work we focus on recording laboratory electronic spectra of neutral and ionised triphenylene between 220 and 780 nm, trapped in H2O ice and solid argon at 12 K. The studies are motivated by the potential for spectroscopic astronomical detection of electronic absorption spectra of PAHs in ice mantles on interstellar grains as discussed by Linnartz (2014), and were performed also in a cold Ar matrix to provide guidance as to whether triphenylene (particularly in its singly positively ionised form) could be a viable candidate for any of the unidentified diffuse interstellar absorption bands. Based on the argon-matrix experimental results, comparison is made with previously unpublished astronomical spectra near 400 nm which contain broad interstellar absorption features consistent with the predictions from the laboratory matrix spectra, thus providing motivation for the recording of gas-phase electronic spectra of the internally cold triphenylene cation.

Application of optical spectroscopic techniques for disease diagnosis

NASA Astrophysics Data System (ADS)

Saha, Anushree

Optical spectroscopy, a truly non-invasive tool for remote diagnostics, is capable of providing valuable information on the structure and function of molecules. However, most spectroscopic techniques suffer from drawbacks, which limit their application. As a part of my dissertation work, I have developed theoretical and experimental methods to address the above mentioned issues. I have successfully applied these methods for monitoring the physical, chemical and biochemical parameters of biomolecules involved in some specific life threatening diseases like lead poisoning and age-related macular degeneration (AMD). I presented optical studies of melanosomes, which are one of the vital organelles in the human eye, also known to be responsible for a disease called age-related macular degeneration (AMD), a condition of advanced degeneration which causes progressive blindness. I used Raman spectroscopy, to first chemically identify the composition of melanosome, and then monitor the changes in its functional and chemical behavior due to long term exposure to visible light. The above study, apart from explaining the role of melanosomes in AMD, also sets the threshold power for lasers used in surgeries and other clinical applications. In the second part of my dissertation, a battery of spectroscopic techniques was successfully applied to explore the different binding sites of lead ions with the most abundant carrier protein molecule in our circulatory system, human serum albumin. I applied optical spectroscopic tools for ultrasensitive detection of heavy metal ions in solution which can also be used for lead detection at a very early stage of lead poisoning. Apart from this, I used Raman microspectroscopy to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low concentrated aqueous extract of a prospective drug, Nerium Oleander. The experimental methods used in this study has tremendous potential for clinical application and will gain widespread acceptance within next few years from bench to bedside as an inexpensive and non-invasive tool compared to the other technologies.

Comparing the MRI-based Goutallier Classification to an experimental quantitative MR spectroscopic fat measurement of the supraspinatus muscle.

PubMed

Gilbert, Fabian; Böhm, Dirk; Eden, Lars; Schmalzl, Jonas; Meffert, Rainer H; Köstler, Herbert; Weng, Andreas M; Ziegler, Dirk

2016-08-22

The Goutallier Classification is a semi quantitative classification system to determine the amount of fatty degeneration in rotator cuff muscles. Although initially proposed for axial computer tomography scans it is currently applied to magnet-resonance-imaging-scans. The role for its clinical use is controversial, as the reliability of the classification has been shown to be inconsistent. The purpose of this study was to compare the semi quantitative MRI-based Goutallier Classification applied by 5 different raters to experimental MR spectroscopic quantitative fat measurement in order to determine the correlation between this classification system and the true extent of fatty degeneration shown by spectroscopy. MRI-scans of 42 patients with rotator cuff tears were examined by 5 shoulder surgeons and were graduated according to the MRI-based Goutallier Classification proposed by Fuchs et al. Additionally the fat/water ratio was measured with MR spectroscopy using the experimental SPLASH technique. The semi quantitative grading according to the Goutallier Classification was statistically correlated with the quantitative measured fat/water ratio using Spearman's rank correlation. Statistical analysis of the data revealed only fair correlation of the Goutallier Classification system and the quantitative fat/water ratio with R = 0.35 (p < 0.05). By dichotomizing the scale the correlation was 0.72. The interobserver and intraobserver reliabilities were substantial with R = 0.62 and R = 0.74 (p < 0.01). The correlation between the semi quantitative MRI based Goutallier Classification system and MR spectroscopic fat measurement is weak. As an adequate estimation of fatty degeneration based on standard MRI may not be possible, quantitative methods need to be considered in order to increase diagnostic safety and thus provide patients with ideal care in regard to the amount of fatty degeneration. Spectroscopic MR measurement may increase the accuracy of the Goutallier classification and thus improve the prediction of clinical results after rotator cuff repair. However, these techniques are currently only available in an experimental setting.

Heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) and their cations.

PubMed

Lee, Edmond P F; Wright, Timothy G

2005-10-08

The heavier alkali-metal monosulfides (KS, RbS, CsS, and FrS) have been studied by high-level ab initio calculations. The RCCSD(T) method has been employed, combined with large flexible valence basis sets. All-electron basis sets are used for potassium and sulfur, with effective core potentials being used for the other metals, describing the core electrons. Potential-energy curves are calculated for the lowest two neutral and cationic states: all neutral monosulfide species have a (2)Pi ground state, in contrast with the alkali-metal monoxide species, which undergo a change in the electronic ground state from (2)Pi to (2)Sigma(+) as the group is descended. In the cases of KS, RbS, and CsS, spin-orbit curves are also calculated. We also calculate potential-energy curves for the lowest (3)Sigma(-) and (3)Pi states of the cations. From the potential-energy curves, spectroscopic constants are derived, and for KS the spectroscopic results are compared to experimental spectroscopic values. Ionization energies, dissociation energies, and heats of formation are also calculated; for KS, we explore the effects of relativity and basis set extrapolation on these values.

Nonionic and zwitterionic forms of glycylglycylarginine as a part of spider silk protein: Spectroscopic and theoretical study

NASA Astrophysics Data System (ADS)

Arı, Hatice; Özpozan, Talat

2016-01-01

Glycylglycylarginine as a part of GGX motif of spider silk spidroin in nonionic (non-GGR) and zwitterionic (zwt-GGR) forms have been examined from theoretical and spectroscopic aspects. The most stable conformational isomers of non-GGR and zwt-GGR were obtained through relaxed scan using the DFT/B3LYP with 6-31G(d) basis set. Nonionic and zwitterionic forms of 310-helix structures of GGR have also been calculated and compared with the most stable conformers obtained as a result of conformer analysis of isolated three peptide structures. This comparison should give an idea about the stability contribution of intermolecular interactions between the 310-helix structured peptide chains. O3LYP and B3PW91 hybrid functionals beside B3LYP have also been used for further calculations of geometry optimization, vibrational analysis, Natural Bond Orbital (NBO) analysis, HOMO-LUMO analysis and hydrogen bonding analysis. Normal Mode Analysis was carried through Potential Energy Distribution (PED) calculations by means of VEDA4 program package. IR and Raman spectra of GGR have also been used to relate the spectroscopic data obtained to electronic and structural features.

Nonionic and zwitterionic forms of glycylglycylarginine as a part of spider silk protein: Spectroscopic and theoretical study.

PubMed

Arı, Hatice; Özpozan, Talat

2016-01-05

Glycylglycylarginine as a part of GGX motif of spider silk spidroin in nonionic (non-GGR) and zwitterionic (zwt-GGR) forms have been examined from theoretical and spectroscopic aspects. The most stable conformational isomers of non-GGR and zwt-GGR were obtained through relaxed scan using the DFT/B3LYP with 6-31G(d) basis set. Nonionic and zwitterionic forms of 310-helix structures of GGR have also been calculated and compared with the most stable conformers obtained as a result of conformer analysis of isolated three peptide structures. This comparison should give an idea about the stability contribution of intermolecular interactions between the 310-helix structured peptide chains. O3LYP and B3PW91 hybrid functionals beside B3LYP have also been used for further calculations of geometry optimization, vibrational analysis, Natural Bond Orbital (NBO) analysis, HOMO-LUMO analysis and hydrogen bonding analysis. Normal Mode Analysis was carried through Potential Energy Distribution (PED) calculations by means of VEDA4 program package. IR and Raman spectra of GGR have also been used to relate the spectroscopic data obtained to electronic and structural features. Copyright © 2015 Elsevier B.V. All rights reserved.

Studies of fission fragment yields via high-resolution γ-ray spectroscopy

NASA Astrophysics Data System (ADS)

Wilson, J. N.; Lebois, M.; Qi, L.; Amador-Celdran, P.; Bleuel, D.; Briz, J. A.; Carroll, R.; Catford, W.; Witte, H. De; Doherty, D. T.; Eloirdi, R.; Georgiev, G.; Gottardo, A.; Goasduff, A.; Hadyñska-Klek, K.; Hauschild, K.; Hess, H.; Ingeberg, V.; Konstantinopoulos, T.; Ljungvall, J.; Lopez-Martens, A.; Lorusso, G.; Lozeva, R.; Lutter, R.; Marini, P.; Matea, I.; Materna, T.; Mathieu, L.; Oberstedt, A.; Oberstedt, S.; Panebianco, S.; Podolyak, Zs.; Porta, A.; Regan, P. H.; Reiter, P.; Rezynkina, K.; Rose, S. J.; Sahin, E.; Seidlitz, M.; Serot, O.; Shearman, R.; Siebeck, B.; Siem, S.; Smith, A. G.; Tveten, G. M.; Verney, D.; Warr, N.; Zeiser, F.; Zielinska, M.

2018-03-01

Precise spectroscopic information on the fast neutron induced fission of the 238U(n,f) reaction was recently gained using a new technique which involved coupling of the Miniball high resolution y-ray spectrometer and the LICORNE directional neutron source. The experiment allowed measurement of the isotopic fission yields for around 40 even-even nuclei at an incident neutron energy of around 2 MeV where yield data are very sparse. In addition spectroscopic information on very neutron-rich fission products was obtained. Results were compared to models, both the JEFF-3.1.1 data base and the GEF code, and large discrepancies for the S1 fission mode in the Sn/Mo isotope pair were discovered. This suggests that current models are overestimating the role played by spherical shell effects in fast neutron induced fission. In late 2017 and 2018 the nu-ball hybrid spectrometer will be constructed at the IPN Orsay to perform further experimental investigations with directional neutrons coupled to a powerful hybrid Ge/LaBr3 detector array. This will open up new possibilities for measurements of fission yields for fast-neutron-induced fission using the spectroscopic technique and will be complimentary to other methods being developed.

Combined spectroscopic and quantum chemical studies of ezetimibe

NASA Astrophysics Data System (ADS)

Prajapati, Preeti; Pandey, Jaya; Shimpi, Manishkumar R.; Srivastava, Anubha; Tandon, Poonam; Velaga, Sitaram P.; Sinha, Kirti

2016-12-01

Ezetimibe (EZT) is a hypocholesterolemic agent used for the treatment of elevated blood cholesterol levels as it lowers the blood cholesterol by blocking the absorption of cholesterol in intestine. Study aims to combine experimental and computational methods to provide insights into the structural and vibrational spectroscopic properties of EZT which is important for explaining drug substance physical and biological properties. Computational study on molecular properties of ezetimibe is presented using density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set. A detailed vibrational assignment has been done for the observed IR and Raman spectra of EZT. In addition to the conformational study, hydrogen bonding and molecular docking studies have been also performed. For conformational studies, the double well potential energy curves have been plotted for the rotation around the six flexible bonds of the molecule. UV absorption spectrum was examined in methanol solvent and compared with calculated one in solvent environment (IEF-PCM) using TD-DFT/6-31G basis set. HOMO-LUMO energy gap of both the conformers have also been calculated in order to predict its chemical reactivity and stability. The stability of the molecule was also examined by means of natural bond analysis (NBO) analysis. To account for the chemical reactivity and site selectivity of the molecules, molecular electrostatic potential (MEPS) map has been plotted. The combination of experimental and calculated results provide an insight into the structural and vibrational spectroscopic properties of EZT. In order to give an insight for the biological activity of EZT, molecular docking of EZT with protein NPC1L1 has been done.

Experimental study of the electric field in a hollow cathode discharge in hydrogen: influence of sputtering

NASA Astrophysics Data System (ADS)

Gonzalez-Fernandez, V.; Grützmacher, K.; Pérez, C.; de la Rosa, M. I.

2017-11-01

Doppler-free two photon optogalvanic spectroscopy was employed in extensive studies to measure the electric field strength in the cathode fall region of a hollow cathode discharge (HCD), operated in pure hydrogen, via the Stark splitting of the 2S level of atomic hydrogen. The high quality measurements, based on an improved cathode design and laser spectroscopic set-up, reveal clear differences in the recorded spectra obtained for different cathode material (stainless steel and tungsten) at otherwise identical discharge conditions. It is well known, that the sputtering rate of tungsten is about four orders of magnitude less compared to stainless steel; hence the hydrogen plasma in front of the stainless steel cathode is much more contaminated by iron compared to tungsten. This study is focussed on analyzing the distortion of the spectra, i.e. the corresponding local electric field strength, depending on cathode material and laser power. We refer the more pronounced distortion of the spectra in case of a stainless steel cathode to the related large contamination of the hydrogen plasma due to atomic iron which is also expanding into the central discharge. Spectra recorded for different laser power, i.e. different spectral irradiance, allow verifying spectroscopic conditions, where the distortion of the spectra becomes quite negligible even for stainless steel cathode.

Spectroscopic and calorimetric studies on the interaction between PAMAM G4-OH and 5-fluorouracil in aqueous solutions

NASA Astrophysics Data System (ADS)

Buczkowski, Adam; Urbaniak, Pawel; Piekarski, Henryk; Palecz, Bartlomiej

2017-01-01

The results of spectroscopic measurements (an increase in solubility, equilibrium dialysis, 1H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate spontaneous (ΔG < 0) binding of 5-fluorouracil molecules by PAMAM G4-OH dendrimer with terminal hydroxyl groups in an aqueous solution. PAMAM G4-OH dendrimer bonds about n = 8 ± 1 molecules of the drug with an equilibrium constant of K = 70 ± 10. The process of saturating the dendrimer active sites by the drug molecules is exothermal (ΔH < 0) and is accompanied by an advantageous change in entropy (ΔS > 0). The parameters of binding 5-fluorouracil by PAMAM G4-OH dendrimer were compared with those of binding this drug by the macromolecules of PAMAM G3-OH and G5-OH.

Spectroscopic Binary Star Studies with the Palomar Testbed Interferometer II

NASA Astrophysics Data System (ADS)

Boden, A. F.; Lane, B. F.; Creech-Eakman, M.; Queloz, D.; PTI Collaboration

1999-12-01

The Palomar Testbed Interferometer (PTI) is a long-baseline near-infrared interferometer located at Palomar Observatory. Following our previous work on resolving spectroscopic binary stars with the Palomar Testbed Interferometer (PTI), we will present a number of new visual and physical orbit determinations derived from integrated reductions of PTI visibility and archival radial velocity data. The six systems for which we will present new orbit models are: 12 Boo (HD 123999), 75 Cnc (HD 78418), 47 And (HD 8374), HD 205539, BY Draconis (HDE 234677), and 3 Boo (HD 120064). Most of these systems are double-lined binary systems (SB2), and integrated astrometric/radial velocity orbit modeling provides precise fundamental parameters (mass, luminosity) and system distance determinations comparable with Hipparcos precisions. The work described in this paper was performed under contract with the National Aeronautics and Space Administration.

Are LOD and LOQ Reliable Parameters for Sensitivity Evaluation of Spectroscopic Methods?

PubMed

Ershadi, Saba; Shayanfar, Ali

2018-03-22

The limit of detection (LOD) and the limit of quantification (LOQ) are common parameters to assess the sensitivity of analytical methods. In this study, the LOD and LOQ of previously reported terbium sensitized analysis methods were calculated by different methods, and the results were compared with sensitivity parameters [lower limit of quantification (LLOQ)] of U.S. Food and Drug Administration guidelines. The details of the calibration curve and standard deviation of blank samples of three different terbium-sensitized luminescence methods for the quantification of mycophenolic acid, enrofloxacin, and silibinin were used for the calculation of LOD and LOQ. A comparison of LOD and LOQ values calculated by various methods and LLOQ shows a considerable difference. The significant difference of the calculated LOD and LOQ with various methods and LLOQ should be considered in the sensitivity evaluation of spectroscopic methods.

Microwave spectroscopic observation of multiple phase transitions in the bilayer electron solid in wide quantum wells

NASA Astrophysics Data System (ADS)

Hatke, Anthony; Engel, Lloyd; Liu, Yang; Shayegan, Mansour; Pfeiffer, Loren; West, Ken; Baldwin, Kirk

2015-03-01

The termination of the low Landau filling factor (ν) fractional quantum Hall series for a single layer two dimensional system results in the formation of a pinned Wigner solid for ν < 1 / 5. In a wide quantum well the system can support a bilayer state in which interlayer and intralayer interactions become comparable, which is measured in traditional transport as an insulating state for ν < 1 / 2. We perform microwave spectroscopic studies of this bilayer state and observe that this insulator exhibits a resonance, a signature of a solid phase. Additionally, we find that as we increase the density of the well at fixed ν this bilayer solid exhibits multiple sharp reductions in the resonance amplitude vs ν. This behavior is characteristic of multiple phase transitions, which remain hidden from dc transport measurements.

Hybrid Biodegradable Hydrogels Obtained from Nanoclay and Carboxymethylcellulose Polysaccharide: Hydrophilic, Kinetic, Spectroscopic and Morphological Properties.

PubMed

Nascimento, Denis W S; de Moura, Márcia R; Mattoso, Luiz H C; Aouada, Fauze A

2017-01-01

In this paper, series of novel nanocomposite hydrogels based on polyacrylamide (PAAm), carboxymethylcellulose (CMC) and nanoclay were synthesized. Hydrophilic, kinetic, spectroscopic and morphological properties were investigated as function of their constituents. Spectroscopic properties confirmed the obtaining of the nanocomposites. It was also observed that the nanocomposites have walls of pores with a more rugged morphology compared with the morphology of the hydrogel without clay, contributing to repel the water molecules. Besides, the results showed that the velocity and quantity of water uptake may be controlled by adjusting of matrix rigidity, i.e., nanoclay content into polymeric matrix. This behavior is required to future application in agriculture fields, specifically as carrier vehicle in controlled release of agrochemicals. Thus, these nanocomposites have technological application.

Measuring water contents in animal organ tissues using terahertz spectroscopic imaging.

PubMed

Lee, Kyumin; Jeoung, Kiyong; Kim, Sang Hoon; Ji, Young-Bin; Son, Hyeyoung; Choi, Yuna; Huh, Young-Min; Suh, Jin-Suck; Oh, Seung Jae

2018-04-01

We investigated the water contents in several organ tissues such as the liver, spleen, kidney, and brain tissue of rats using the terahertz spectroscopic imaging technique. The water contents of the tissues were determined by using a simple equation containing the absorption coefficients of fresh and lyophilized tissues and water. We compared the measured water contents with the difference in mass of tissues before and after lyophilization. All results showed a good match except for the kidney, which has several Bowman's capsules.

A new 1,2-ethanedione benzofurane derivative from Tephrosia purpurea.

PubMed

Peng, Yan; Chen, Yinning; Gao, Chenghai; Yan, Tao; Cao, Wenhao; Huang, Riming

2014-01-01

A new 1,2-ethanedione benzofurane derivative, purpdione (1), was isolated from Tephrosia purpurea, together with seven known flavonoids, purpurenone (2), pongamol (3), ovalitenin A (4), karanjin (5), lanceolatin B (6), tachrosin (7) and villosinol (8). The new structure was elucidated based on the analysis of its spectroscopic data. The structures of the known compounds were identified by comparing their spectroscopic data with those reported in the literature. The isolates exhibited marginal ability to inhibit the settlement of barnacle (Balanus reticulatus).

Hepatitis C virus inhibitory hydrolysable tannins from the fruits of Terminalia chebula.

PubMed

Ajala, Olusegun S; Jukov, Azzaya; Ma, Chao-Mei

2014-12-01

Two new hydrolysable tannins, chebumeinin A (1) and chebumeinin B (2), together with eight known related compounds (3-10), were isolated from the fruits of Terminalia chebula. The new compounds were structurally determined by analysis of their spectroscopic data and the known compounds characterized by comparing their spectroscopic data with literature values. All isolates were evaluated by an HCV protease inhibition assay, and some compounds were found to be potently active. Copyright © 2014 Elsevier B.V. All rights reserved.

Recent advances and remaining challenges for the spectroscopic detection of explosive threats.

PubMed

Fountain, Augustus W; Christesen, Steven D; Moon, Raphael P; Guicheteau, Jason A; Emmons, Erik D

2014-01-01

In 2010, the U.S. Army initiated a program through the Edgewood Chemical Biological Center to identify viable spectroscopic signatures of explosives and initiate environmental persistence, fate, and transport studies for trace residues. These studies were ultimately designed to integrate these signatures into algorithms and experimentally evaluate sensor performance for explosives and precursor materials in existing chemical point and standoff detection systems. Accurate and validated optical cross sections and signatures are critical in benchmarking spectroscopic-based sensors. This program has provided important information for the scientists and engineers currently developing trace-detection solutions to the homemade explosive problem. With this information, the sensitivity of spectroscopic methods for explosives detection can now be quantitatively evaluated before the sensor is deployed and tested.

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

NASA Astrophysics Data System (ADS)

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

2012-10-01

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

Review of spectroscopic parameters for upper atmospheric measurements

NASA Technical Reports Server (NTRS)

Smith, M. A. H. (Editor)

1985-01-01

The workshop included communication of spectroscopic data requirements for the planned upper atmosphere research satellite (UARS) mission, review of the status of currently available spectroscopic parameters, and recommendation of additional studies. The objectives were accomplished and resulted in a series of general and specific recommendations for laboratory spectroscopy research to meet the needs of UARS and other atmospheric remote sensing programs.

A simple quasi-diabatization scheme suitable for spectroscopic problems based on one-electron properties of interacting states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cave, Robert J., E-mail: Robert-Cave@hmc.edu; Stanton, John F., E-mail: JFStanton@gmail.com

We present a simple quasi-diabatization scheme applicable to spectroscopic studies that can be applied using any wavefunction for which one-electron properties and transition properties can be calculated. The method is based on rotation of a pair (or set) of adiabatic states to minimize the difference between the given transition property at a reference geometry of high symmetry (where the quasi-diabatic states and adiabatic states coincide) and points of lower symmetry where quasi-diabatic quantities are desired. Compared to other quasi-diabatization techniques, the method requires no special coding, facilitates direct comparison between quasi-diabatic quantities calculated using different types of wavefunctions, and ismore » free of any selection of configurations in the definition of the quasi-diabatic states. On the other hand, the method appears to be sensitive to multi-state issues, unlike recent methods we have developed that use a configurational definition of quasi-diabatic states. Results are presented and compared with two other recently developed quasi-diabatization techniques.« less

Development of quality control and instrumentation performance metrics for diffuse optical spectroscopic imaging instruments in the multi-center clinical environment

NASA Astrophysics Data System (ADS)

Keene, Samuel T.; Cerussi, Albert E.; Warren, Robert V.; Hill, Brian; Roblyer, Darren; Leproux, AnaÑ--s.; Durkin, Amanda F.; O'Sullivan, Thomas D.; Haghany, Hosain; Mantulin, William W.; Tromberg, Bruce J.

2013-03-01

Instrument equivalence and quality control are critical elements of multi-center clinical trials. We currently have five identical Diffuse Optical Spectroscopic Imaging (DOSI) instruments enrolled in the American College of Radiology Imaging Network (ACRIN, #6691) trial located at five academic clinical research sites in the US. The goal of the study is to predict the response of breast tumors to neoadjuvant chemotherapy in 60 patients. In order to reliably compare DOSI measurements across different instruments, operators and sites, we must be confident that the data quality is comparable. We require objective and reliable methods for identifying, correcting, and rejecting low quality data. To achieve this goal, we developed and tested an automated quality control algorithm that rejects data points below the instrument noise floor, improves tissue optical property recovery, and outputs a detailed data quality report. Using a new protocol for obtaining dark-noise data, we applied the algorithm to ACRIN patient data and successfully improved the quality of recovered physiological data in some cases.

Chiral self-recognition: direct spectroscopic detection of the homochiral and heterochiral dimers of propylene oxide in the gas phase.

PubMed

Su, Zheng; Borho, Nicole; Xu, Yunjie

2006-12-27

In this report, we describe rotational spectroscopic and high-level ab initio studies of the 1:1 chiral molecular adduct of propylene oxide dimer. The complexes are bound by weak secondary hydrogen bonds, that is, the O(epoxy)...H-C noncovalent interactions. Six homochiral and six heterochiral conformers were predicted to be the most stable configurations where each monomer acts as a proton acceptor and a donor simultaneously, forming two six- or five-membered intermolecular hydrogen-bonded rings. Rotational spectra of six, that is, three homochiral and heterochiral conformer pairs, out of the eight conformers that were predicted to have sufficiently large permanent electric dipole moments were measured and analyzed. The relative conformational stability order and the signs of the chiral recognition energies of the six conformers were determined experimentally and were compared to the ab initio computational results. The experimental observations and the ab initio calculations suggest that the concerted effort of these weak secondary hydrogen bonds can successfully lock the subunits in a particular orientation and that the overall binding strength is comparable to a classic hydrogen bond.

An empirical evaluation of three vibrational spectroscopic methods for detection of aflatoxins in maize.

PubMed

Lee, Kyung-Min; Davis, Jessica; Herrman, Timothy J; Murray, Seth C; Deng, Youjun

2015-04-15

Three commercially available vibrational spectroscopic techniques, including Raman, Fourier transform near infrared reflectance (FT-NIR), and Fourier transform infrared (FTIR) were evaluated to help users determine the spectroscopic method best suitable for aflatoxin analysis in maize (Zea mays L.) grain based on their relative efficiency and predictive ability. Spectral differences of Raman and FTIR spectra were more marked and pronounced among aflatoxin contamination groups than those of FT-NIR spectra. From the observations and findings in our current and previous studies, Raman and FTIR spectroscopic methods are superior to FT-NIR method in terms of predictive power and model performance for aflatoxin analysis and they are equally effective and accurate in predicting aflatoxin concentration in maize. The present study is considered as the first attempt to assess how spectroscopic techniques with different physical processes can influence and improve accuracy and reliability for rapid screening of aflatoxin contaminated maize samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Optical spectroscopic characteristics of lactate and mitochondrion as new biomarkers in cancer diagnosis: understanding Warburg effect

NASA Astrophysics Data System (ADS)

Liu, C.-H.; Ni, X. H.; Pu, Yang; Yang, Y. L.; Zhou, F.; Zuzolo, R.; Wang, W. B.; Masilamani, V.; Rizwan, A.; Alfano, R. R.

2012-01-01

Cancer cells display high rates of glycolysis even under normoxia and mostly under hypoxia. Warburg proposed this effect of altered metabolism in cells more than 80 years ago. It is considered as a hallmark of cancer. Optical spectroscopy can be used to explore this effect. Pathophysiological studies indicate that mitochondria of cancer cells are enlarged and increased in number. Warburg observed that cancer cells tend to convert most glucose to lactate regardless of the presence of oxygen. Previous observations show increased lactate in breast cancer lines. The focus of this study is to investigate the relative content changes of lactate and mitochondria in human cancerous and normal breast tissue samples using optical spectroscopic techniques. The optical spectra were obtained from 30 cancerous and 25 normal breast tissue samples and five model components (Tryptophan, fat, collagen, lactate and mitochondrion) using fluorescence, Stokes shift and Raman spectroscopy. The basic biochemical component analysis model (BBCA) and a set of algorithm were used to analyze the spectra. Our analyses of fluorescence spectra showed a 14 percent increase in lactate content and 2.5 times increase in mitochondria number in cancerous breast tissue as compared with normal tissue. Our findings indicate that optical spectroscopic techniques may be used to understand Warburg effect. Lactate and mitochondrion content changes in tumors examined using optical spectroscopy may be used as a prognostic molecular marker in clinic applications.

A comparative spectroscopic and kinetic study of photoexcitations in detergent-isolated and membrane-embedded LH2 light-harvesting complexes.

PubMed

Freiberg, Arvi; Rätsep, Margus; Timpmann, Kõu

2012-08-01

Integral membrane proteins constitute more than third of the total number of proteins present in organisms. Solubilization with mild detergents is a common technique to study the structure, dynamics, and catalytic activity of these proteins in purified form. However beneficial the use of detergents may be for protein extraction, the membrane proteins are often denatured by detergent solubilization as a result of native lipid membrane interactions having been modified. Versatile investigations of the properties of membrane-embedded and detergent-isolated proteins are, therefore, required to evaluate the consequences of the solubilization procedure. Herein, the spectroscopic and kinetic fingerprints have been established that distinguish excitons in individual detergent-solubilized LH2 light-harvesting pigment-protein complexes from them in the membrane-embedded complexes of purple photosynthetic bacteria Rhodobacter sphaeroides. A wide arsenal of spectroscopic techniques in visible optical range that include conventional broadband absorption-fluorescence, fluorescence anisotropy excitation, spectrally selective hole burning and fluorescence line-narrowing, and transient absorption-fluorescence have been applied over broad temperature range between physiological and liquid He temperatures. Significant changes in energetics and dynamics of the antenna excitons upon self-assembly of the proteins into intracytoplasmic membranes are observed, analyzed, and discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. Copyright © 2011. Published by Elsevier B.V.

Biosensing via light scattering from plasmonic core-shell nanospheres coated with DNA molecules

NASA Astrophysics Data System (ADS)

Xie, Huai-Yi; Chen, Minfeng; Chang, Yia-Chung; Moirangthem, Rakesh Singh

2017-05-01

We present both experimental and theoretical studies for investigating DNA molecules attached on metallic nanospheres. We have developed an efficient and accurate numerical method to investigate light scattering from plasmonic nanospheres on a substrate covered by a shell, based on the Green's function approach with suitable spherical harmonic basis. Next, we use this method to study optical scattering from DNA molecules attached to metallic nanoparticles placed on a substrate and compare with experimental results. We obtain fairly good agreement between theoretical predictions and the measured ellipsometric spectra. The metallic nanoparticles were used to detect the binding with DNA molecules in a microfluidic setup via spectroscopic ellipsometry (SE), and a detectable change in ellipsometric spectra was found when DNA molecules are captured on Au nanoparticles. Our theoretical simulation indicates that the coverage of Au nanosphere by a submonolayer of DNA molecules, which is modeled by a thin layer of dielectric material (which may absorb light), can lead to a small but detectable spectroscopic shift in both the Ψ and Δ spectra with more significant change in Δ spectra in agreement with experimental results. Our studies demonstrated the ultrasensitive capability of SE for sensing submonolayer coverage of DNA molecules on Au nanospheres. Hence the spectroscopic ellipsometric measurements coupled with theoretical analysis via an efficient computation method can be an effective tool for detecting DNA molecules attached on Au nanoparticles, thus achieving label-free, non-destructive, and high-sensitivity biosensing with nanoscale resolution.

Spectroscopic characteristics and biodegradability of cold and hot water-extractable soil organic matter under different land uses in subarctic Alaska

USDA-ARS?s Scientific Manuscript database

Cold (22 degrees C) and hot water (80 degrees C) extractions have been used to estimate labile organic C and N in soils. The aim of this study was to comparatively assess chemical characteristics and biodegradability of water extractable organic matter (WEOM) at 22 and 80 degrees C in 14 Alaskan soi...

DNA-Binding Interaction Studies of Microwave Assisted Synthesized Sulfonamide Substituted 8-Hydroxyquinoline Derivatives.

PubMed

Dixit, Ritu B; Patel, Tarosh S; Vanparia, Satish F; Kunjadiya, Anju P; Keharia, Harish R; Dixit, Bharat C

2011-01-01

Sulfonamide substituted 8-hydroxyquinoline derivatives were prepared using a microwave synthesizer. The interaction of sulfonamide substituted 8-hydroxyquinoline derivatives and their transition metal complexes with Plasmid (pUC 19) DNA and Calf Thymus DNA were investigated by UV spectroscopic studies and gel electrophoresis measurements. The interaction between ligand/metal complexes and DNA was carried out by increasing the concentration of DNA from 0 to 12 μl in UV spectroscopic study, while the concentration of DNA in gel electrophoresis remained constant at 10 μl. These studies supported the fact that, the complex binds to DNA by intercalation via ligand into the base pairs of DNA. The relative binding efficacy of the complexes to DNA was much higher than the binding efficacy of ligands, especially the complex of Cu-AHQMBSH had the highest binding ability to DNA. The mobility of the bands decreased as the concentration of the complex was increased, indicating that there was increase in the interaction between the metal ion and DNA. Complexes of AHQMBSH were excellent for DNA binding as compared to HQMABS.

Improving 1H MRSI measurement of cerebral lactate for clinical applications.

PubMed

Corrigan, Neva M; Richards, Todd L; Friedman, Seth D; Petropoulos, Helen; Dager, Stephen R

2010-04-30

Accurate measurement of cerebral lactate is critical to the understanding of brain function for psychiatric disorders such as panic disorder and bipolar disorder as well as mitochondrial dysfunction. Proton magnetic spectroscopic imaging (MRSI) techniques can be used to study lactate in vivo; however, accurate measurement of cerebral lactate, which is normally at low basal abundance, can be challenging. In this study, regional lactate measurements obtained with two different MRSI analytic approaches were evaluated using proton echo-planar spectroscopic imaging (PEPSI) data from 18 healthy adults participating in an in vivo sodium lactate infusion study. The results demonstrate that averaging data within a region of interest (ROI) before spectral fitting with LCModel results in significantly improved lactate measurement as compared to averaging chemical concentrations derived from the fitting of individual voxels in the ROI. Simulation results that confirm this finding are also presented. This study additionally outlines an atlas-based approach for the systematic computation of regional distributions of chemical concentrations in large MRSI data sets. Copyright @ 2009 Elsevier Ireland Ltd. All rights reserved.

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

PubMed

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

2015-03-15

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of high-pressure liquid chromatography (HPLC) and Griess reagent-spectroscopic methods for the measurement of nitrate in serum from healthy individuals in the Nordic countries.

PubMed

Larsen, Tine Lise; Nilsen, Valentina; Andersen, Dag Olav; Francis, George; Rustad, Pål; Mansoor, Mohammad Azam

2008-12-01

Bioavailability of NO can be estimated by measuring the concentration of nitrate (NO(3)) in serum. However, the methods used for the measurement NO(3) in plasma or serum show a great degree of variation. Therefore, we compared two analytical methods for the measurement of NO(3) in serum. The concentration of NO(3) in 600 serum samples collected from healthy individuals was determined by the HPLC and by the Griess reagent-spectroscopic method. The concentration of NO(3) in the samples was 29.4+/-16.1 micromol/L and 26.2+/-14.0 micromol/L (mean+/-SD) measured by HPLC and Griess reagent-spectroscopic method respectively (p<0.0001). We detected a significant correlation between the two methods (R=0.81, p<0.0001). A significant correlation between the two methods may suggest that either method can be used for the measurement of NO(3) in serum, however the Griess reagent-spectroscopic method measures lower concentrations of NO(3) than the HPLC method.

Spectroscopic Studies of Double Beta Decays and MOON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ejiri, H.; Nuclear Science, Czech Technical University, Brehova, Prague, Czech Republic, National Institute of Radiological Sciences, Chiba, 263-8555

2007-10-12

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.

Importance of tissue preparation methods in FTIR micro-spectroscopical analysis of biological tissues: 'traps for new users'.

PubMed

Zohdi, Vladislava; Whelan, Donna R; Wood, Bayden R; Pearson, James T; Bambery, Keith R; Black, M Jane

2015-01-01

Fourier Transform Infrared (FTIR) micro-spectroscopy is an emerging technique for the biochemical analysis of tissues and cellular materials. It provides objective information on the holistic biochemistry of a cell or tissue sample and has been applied in many areas of medical research. However, it has become apparent that how the tissue is handled prior to FTIR micro-spectroscopic imaging requires special consideration, particularly with regards to methods for preservation of the samples. We have performed FTIR micro-spectroscopy on rodent heart and liver tissue sections (two spectroscopically very different biological tissues) that were prepared by desiccation drying, ethanol substitution and formalin fixation and have compared the resulting spectra with that of fully hydrated freshly excised tissues. We have systematically examined the spectra for any biochemical changes to the native state of the tissue caused by the three methods of preparation and have detected changes in infrared (IR) absorption band intensities and peak positions. In particular, the position and profile of the amide I, key in assigning protein secondary structure, changes depending on preparation method and the lipid absorptions lose intensity drastically when these tissues are hydrated with ethanol. Indeed, we demonstrate that preserving samples through desiccation drying, ethanol substitution or formalin fixation significantly alters the biochemical information detected using spectroscopic methods when compared to spectra of fresh hydrated tissue. It is therefore imperative to consider tissue preparative effects when preparing, measuring, and analyzing samples using FTIR spectroscopy.

Convolutional neural networks for vibrational spectroscopic data analysis.

PubMed

Acquarelli, Jacopo; van Laarhoven, Twan; Gerretzen, Jan; Tran, Thanh N; Buydens, Lutgarde M C; Marchiori, Elena

2017-02-15

In this work we show that convolutional neural networks (CNNs) can be efficiently used to classify vibrational spectroscopic data and identify important spectral regions. CNNs are the current state-of-the-art in image classification and speech recognition and can learn interpretable representations of the data. These characteristics make CNNs a good candidate for reducing the need for preprocessing and for highlighting important spectral regions, both of which are crucial steps in the analysis of vibrational spectroscopic data. Chemometric analysis of vibrational spectroscopic data often relies on preprocessing methods involving baseline correction, scatter correction and noise removal, which are applied to the spectra prior to model building. Preprocessing is a critical step because even in simple problems using 'reasonable' preprocessing methods may decrease the performance of the final model. We develop a new CNN based method and provide an accompanying publicly available software. It is based on a simple CNN architecture with a single convolutional layer (a so-called shallow CNN). Our method outperforms standard classification algorithms used in chemometrics (e.g. PLS) in terms of accuracy when applied to non-preprocessed test data (86% average accuracy compared to the 62% achieved by PLS), and it achieves better performance even on preprocessed test data (96% average accuracy compared to the 89% achieved by PLS). For interpretability purposes, our method includes a procedure for finding important spectral regions, thereby facilitating qualitative interpretation of results. Copyright © 2016 Elsevier B.V. All rights reserved.

A Spectroscopic Survey of Lensed Dwarf Galaxies at 1

NASA Astrophysics Data System (ADS)

Alavi, Anahita; Siana, Brian; gburek, Timothy; Richard, Johan; Teplitz, Harry; Rafelski, Marc; Stark, Daniel P.; Anahita Alavi

2018-01-01

High-redshift dwarf galaxies (M<109 M⊙) are one of the primary targets of the James Web Space Telescope. Recent studies have suggested that these galaxies are different than their bright counterparts, as they follow a divergent evolutionary history of star formation. In our previous study, utilizing the magnification from massive clusters of galaxies (Hubble Frontier Fields), we found a large sample of dwarf star-forming galaxies at the peak epoch of star formation (1

Studies on the synthesis, spectroscopic analysis, molecular docking and DFT calculations on 1-hydroxy-2-(4-hydroxyphenyl)-4,5-dimethyl-imidazol 3-oxide

NASA Astrophysics Data System (ADS)

Benzon, K. B.; Sheena, Mary Y.; Panicker, C. Yohannan; Armaković, Stevan; Armaković, Sanja J.; Pradhan, Kiran; Nanda, Ashis Kumar; Van Alsenoy, C.

2017-02-01

In this work we have investigated in details the spectroscopic and reactive properties of newly synthesized imidazole derivative, namely the 1-hydroxy-2-(4-hydroxyphenyl)-4,5-dimethyl-imidazole 3-oxide (HHPDI). FT-IR and NMR spectra were measured and compared with theoretically obtained data provided by calculations of potential energy distribution and chemical shifts, respectively. Insight into the global reactivity properties has been obtained by analysis of frontier molecular orbitals, while local reactivity properties have been investigated by analysis of charge distribution, ionization energies and Fukui functions. NBO analysis was also employed to understand the stability of molecule, while hyperpolarizability has been calculated in order to assess the nonlinear optical properties of title molecule. Sensitivity towards autoxidation and hydrolysis mechanisms has been investigated by calculations of bond dissociation energies and radial distribution functions, respectively. Molecular docking study was also performed, in order to determine the pharmaceutical potential of the investigated molecule.

Early prognostic markers for fatal fulminant hepatic failure cases with viral hepatitis: proton nuclear magnetic resonance spectroscopic studies of serum.

PubMed

Bala, Lakshmi; Mehrotra, Mayank; Mohindra, Samir; Saxena, Rajan; Khetrapal, Chunni Lal

2013-02-01

Fulminant hepatic failure is associated with liver metabolic derangements which could have fatal consequences. The aim of the present study is to identify serum markers for early prediction of the outcome. Proton nuclear magnetic resonance spectroscopic studies of serum of fulminant hepatic failure patients due to viral hepatitis with grade II/III of encephalopathy (twenty-four: ten prospective and fourteen retrospective) and twenty-five controls were undertaken. Of the twenty-four patients, fifteen survived with medical management alone while nine had fatal outcome. The results demonstrated significantly elevated indices of amino acids (alanine, lysine, glutamine, histidine, tyrosine, phenylalanine and 1,2-propanediol) in fatal cases compared to survivors and controls. Principal component analysis showed clear separation of fatal and surviving cases. Liver function parameters were significantly deranged in patients but they failed to provide early significant differences between surviving and fatal cases. Compared to model for end-stage liver disease scores, principal component analysis appear to be better as an early prognostic indicator. Biochemical mapping of pathways suggested interruptions in amino acid metabolism and urea cycle. Proton nuclear magnetic resonance studies of serum have the potential of rapidly identifying patients with irreversible fulminant hepatic failure requiring liver transplantation as life saving option. Copyright © 2012 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Autofluorescence spectroscopy for multimodal tissues characterization in colitis-associated cancer murine model

NASA Astrophysics Data System (ADS)

Dorez, Hugo; Sablong, Raphaël.; Canaple, Laurence; Saint-Jalmes, Hervé; Gaillard, Sophie; Moussata, Driffa; Beuf, Olivier

2015-07-01

The purpose of this research project is to assess mice colon wall, using three optical modalities (conventional endoscopy, confocal endomicroscopy and optical spectroscopy) and endoluminal MRI. The study is done in the context of inflammatory bowel disease and colorectal cancer that represent 13% of new cases of cancer, every year in western countries. An optical spectroscopic bench (autofluorescence and reflectance) was developed with a flexible fiber probe. This latter has been combined with a mini multi-purpose rigid endoscope and a confocal endomicroscope. The optical modalities were first used in vivo on SWISS mice. Then, a specific optical a phantom (containing two layers of distinct fluorophores) was developed in order to evaluate our two-channel spectroscopic probe as a basic depth-sensitive measurement tool. The preliminary results show the feasibility to combine such modalities in the same in vivo protocol. Conventional endoscopy is useful to depict inflammation along colon wall. Confocal endomicroscopy provides high-contrasted images of microvascularization. Measured optical spectra both depend on biochemical tissue content and layered structure of the medium. The light collected from one channel is not similar to the other, in terms of intensity and spectroscopic profile as the interaction with the medium observed volume is different. A comparative analysis of the spectra based on our in vitro model exhibits a strong correlation between simple index extracted from spectral data and two main phantom characteristics (fluorophore concentrations and superficial layer thickness). This work suggests that this technique could contribute to assess tissues alterations through autofluorescence spectroscopic measurement under endoscopy.

Effect of polyvinylpyrrolidone content on alternating current conductivity of polyaniline

NASA Astrophysics Data System (ADS)

Megha, R.; Kumar, T. G. Naveen; Ravikiran, Y. T.; Prakash, H. G. Raj; Revanasiddappa, M.; Kumari, S. C. Vijaya

2018-05-01

In the present work, Polyaniline (PANI) and Polyaniline-polyvinylpyrrolidone (PANI-PVP) composites of two different weight percentages of PVP were synthesized separately by simple chemical polymerization method. The interaction between PANI and PVP in each of the composite was confirmed by Attenuated total reflection infrared spectroscopic (AT-IR) technique. The alternate current (AC) response characteristics at room temperature of PANI and the composites in the frequency range 50 Hz-1 MHz were comparatively studied. Both the composites have shown decreased conductivity as compared to that of PANI.

SPIDERS: the spectroscopic follow-up of X-ray-selected clusters of galaxies in SDSS-IV

DOE PAGES

Clerc, N.; Merloni, A.; Zhang, Y. -Y.; ...

2016-09-05

SPIDERS (The SPectroscopic IDentification of ERosita Sources) is a programme dedicated to the homogeneous and complete spectroscopic follow-up of X-ray active galactic nuclei and galaxy clusters over a large area (~7500 deg 2) of the extragalactic sky. SPIDERS is part of the Sloan Digital Sky Survey (SDSS)-IV project, together with the Extended Baryon Oscillation Spectroscopic Survey and the Time-Domain Spectroscopic Survey. This study describes the largest project within SPIDERS before the launch of eROSITA: an optical spectroscopic survey of X-ray-selected, massive (~10 14–10 15 M⊙) galaxy clusters discovered in ROSAT and XMM–Newton imaging. The immediate aim is to determine precisemore » (Δz ~ 0.001) redshifts for 4000–5000 of these systems out to z ~ 0.6. The scientific goal of the program is precision cosmology, using clusters as probes of large-scale structure in the expanding Universe. We present the cluster samples, target selection algorithms and observation strategies. We demonstrate the efficiency of selecting targets using a combination of SDSS imaging data, a robust red-sequence finder and a dedicated prioritization scheme. We describe a set of algorithms and work-flow developed to collate spectra and assign cluster membership, and to deliver catalogues of spectroscopically confirmed clusters. We discuss the relevance of line-of-sight velocity dispersion estimators for the richer systems. We illustrate our techniques by constructing a catalogue of 230 spectroscopically validated clusters (0.031 < z < 0.658), found in pilot observations. Finally, we discuss two potential science applications of the SPIDERS sample: the study of the X-ray luminosity-velocity dispersion (LX–σ) relation and the building of stacked phase-space diagrams.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ng, Cheuk-Yiu

2016-04-25

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

IN-SYNC. VII. Evidence for a Decreasing Spectroscopic Binary Fraction (from 1 to 100 Myr) within the IN-SYNC Sample

NASA Astrophysics Data System (ADS)

Jaehnig, Karl; Bird, Jonathan C.; Stassun, Keivan G.; Da Rio, Nicola; Tan, Jonathan C.; Cotaar, Michiel; Somers, Garrett

2017-12-01

We study the occurrence of spectroscopic binaries in young star-forming regions using the INfrared Spectroscopy of Young Nebulous Clusters (IN-SYNC) survey, carried out in SDSS-III with the APOGEE spectrograph. Multi-epoch observations of thousands of low-mass stars in Orion A, NGC 2264, NGC 1333, IC 348, and the Pleiades have been carried out, yielding H-band spectra with a nominal resolution of R = 22,500 for sources with H < 12 mag. Radial velocity precisions of ˜0.3 {km} {{{s}}}-1 were achieved, which we use to identify radial velocity variations indicative of undetected companions. We use Monte Carlo simulations to assess the types of spectroscopic binaries to which we are sensitive, finding sensitivity to binaries with orbital periods ≲ {10}3.5 days, for stars with 2500 {{K}}≤slant {T}{eff}≤slant 6000 {{K}} and v \\sin i < 100 {km} {{{s}}}-1. Using Bayesian inference, we find evidence for a decline in the spectroscopic binary fraction, by a factor of 3-4, from the age of our pre-main-sequence (PMS) sample to the Pleiades age . The significance of this decline is weakened if spot-induced radial-velocity jitter is strong in the sample, and is only marginally significant when comparing any one of the PMS clusters against the Pleiades. However, the same decline in both sense and magnitude is found for each of the five PMS clusters, and the decline reaches a statistical significance of greater than 95% confidence when considering the PMS clusters jointly. Our results suggest that dynamical processes disrupt the widest spectroscopic binaries ({P}{orb}≈ {10}3{--}{10}4 days) as clusters age, indicating that this occurs early in the stars’ evolution, while they still reside within their nascent clusters.

Measurements of density, temperature, and their fluctuations in turbulent supersonic flow using UV laser spectroscopy

NASA Technical Reports Server (NTRS)

Fletcher, Douglas G.; Mckenzie, R. L.

1992-01-01

Nonintrusive measurements of density, temperature, and their turbulent fluctuation levels were obtained in the boundary layer of an unseeded, Mach 2 wind tunnel flow. The spectroscopic technique that was used to make the measurements is based on the combination of laser-induced oxygen fluorescence and Raman scattering by oxygen and nitrogen from the same laser pulse. Results from this demonstration experiment are compared with previous measurements obtained in the same facility using conventional probes and an earlier spectroscopic technique. Densities and temperatures measured with the current technique agree with the previous surveys to within 3 percent and 2 percent, respectively. The fluctuation amplitudes for both variables agree with the measurements obtained using the earlier spectroscopic technique and show evidence of an unsteady, weak shock wave that perturbs the boundary layer.

A 'first principles' potential energy surface for liquid water from VRT spectroscopy of water clusters.

PubMed

Goldman, Nir; Leforestier, Claude; Saykally, R J

2005-02-15

We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface (the third fitting of the Anisotropic Site Potential with Woermer dispersion to vibration-rotation-tunnelling data). VRT(ASP-W)III is shown to not only be a model of high 'spectroscopic' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared with those from ab initio molecular dynamics, other potentials of 'spectroscopic' accuracy and with experiment. The results herein represent the first time to the authors' knowledge that a 'spectroscopic' potential surface is able to correctly model condensed phase properties of water.

Has your ancient stamp been regummed with synthetic glue? A FT-NIR and FT-Raman study.

PubMed

Simonetti, Remo; Oliveri, Paolo; Henry, Adrien; Duponchel, Ludovic; Lanteri, Silvia

2016-01-01

The potential of FT-NIR and FT-Raman spectroscopies to characterise the gum applied on the backside of ancient stamps was investigated for the first time. This represents a very critical issue for the collectors' market, since gum conditions heavily influence stamp quotations, and fraudulent application of synthetic gum onto damaged stamp backsides to increase their desirability is a well-documented practice. Spectral data were processed by exploratory pattern recognition tools. In particular, application of principal component analysis (PCA) revealed that both of the spectroscopic techniques provide information useful to characterise stamp gum. Examination of PCA loadings and their chemical interpretation confirmed the robustness of the outcomes. Fusion of FT-NIR and FT-Raman spectral data was performed, following both a low-level and a mid-level procedure. The results were critically compared with those obtained separately for the two spectroscopic techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic properties and theoretical studies of bis-Schiff bases derived from polyamine and pyrazolones.

PubMed

Ren, Tiegang; Liu, Shuyun; Li, Guihui; Zhang, Jinglai; Guo, Jia; Li, Weijie; Yang, Lirong

2012-11-01

A series of novel bis-Schiff base were synthesized from 1-aryl-3-methyl-4-benzoyl-5-pyrazolones and diethylenetriamine (or triethylenetetramine) as the starting materials. All of these bis-Schiff bases were characterized by means of NMR, IR, and MS. The UV-vis absorption spectra and fluorescent spectra of these bis-Schiff bases were also measured. Moreover, the B3LYP/6-31G(d) method was used to optimize the ground state geometry of the bis-Schiff bases; and the UV-vis spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVDZ basis set of TD-B3LYP method. It has been found that all of these bis-Schiff bases show a remarkable absorption peak in a wavelength range of 270-340 nm; and their maximum emission peaks are around 348 nm. Copyright © 2012 Elsevier B.V. All rights reserved.

Temperature analysis of laser ignited metalized material using spectroscopic technique

NASA Astrophysics Data System (ADS)

Bassi, Ishaan; Sharma, Pallavi; Daipuriya, Ritu; Singh, Manpreet

2018-05-01

The temperature measurement of the laser ignited aluminized Nano energetic mixture using spectroscopy has a great scope in in analysing the material characteristic and combustion analysis. The spectroscopic analysis helps to do in depth study of combustion of materials which is difficult to do using standard pyrometric methods. Laser ignition was used because it consumes less energy as compared to electric ignition but ignited material dissipate the same energy as dissipated by electric ignition and also with the same impact. Here, the presented research is primarily focused on the temperature analysis of energetic material which comprises of explosive material mixed with nano-material and is ignited with the help of laser. Spectroscopy technique is used here to estimate the temperature during the ignition process. The Nano energetic mixture used in the research does not comprise of any material that is sensitive to high impact.

Quantifying the effect of finite spectral bandwidth on extinction coefficient of species in laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Singh, Manjeet; Singh, Jaswant; Singh, Baljit; Ghanshyam, C.

2016-11-01

The aim of this study is to quantify the finite spectral bandwidth effect on laser absorption spectroscopy for a wide-band laser source. Experimental analysis reveals that the extinction coefficient of an analyte is affected by the bandwidth of the spectral source, which may result in the erroneous conclusions. An approximate mathematical model has been developed for optical intensities having Gaussian line shape, which includes the impact of source's spectral bandwidth in the equation for spectroscopic absorption. This is done by introducing a suitable first order and second order bandwidth approximation in the Beer-Lambert law equation for finite bandwidth case. The derived expressions were validated using spectroscopic analysis with higher SBW on a test sample, Rhodamine B. The concentrations calculated using proposed approximation, were in significant agreement with the true values when compared with those calculated with conventional approach.

Evaluating the influence of particulate matter on spectroscopic measurements of a combusting flow

NASA Astrophysics Data System (ADS)

Herlan, Jonathan; Murray, Nathan

2017-11-01

An adiabatic table-top burner has been used to develop a method for estimating the temperature and concentration of OH in a measurement volume of a non-premixed, hydrogen-air flame. The estimation method uses a nonlinear curve-fitting routine to compare experimental absorption spectra with a model derived, using statistical mechanics, from the Beer-Lambert law. With the aim of applying this method to the analysis of rocket exhaust plumes, this study evaluates whether or not it provides faithful estimates of temperature and OH concentration when the combusting flow contains particulate matter-such as soot or tracers used for particle image velocimetry (PIV) measurements. The hydrogen line of the table-top burner will be seeded with alumina, Al2O3, particles and their influence on spectroscopic measurements elucidated. The authors wish to thank Mr. Bernard Jansen for his support and insight in laboratory activities.

Fluorescence Spectroscopic Properties of Normal and Abnormal Biomedical Materials

NASA Astrophysics Data System (ADS)

Pradhan, Asima

Steady state and time-resolved optical spectroscopy and native fluorescence is used to study the physical and optical properties occurring in diseased and non-diseased biological human tissue, in particular, cancer of the human breast, artery and the dynamics of a photosensitizer useful in photodynamic therapy. The main focus of the research is on the optical properties of cancer and atherosclerotic tissues as compared to their normal counterparts using the different luminescence based spectroscopic techniques such as steady state fluorescence, time-resolved fluorescence, excitation spectroscopy and phosphorescence. The excitation and steady-state spectroscopic fluorescence using visible excitation wavelength displays a difference between normal and malignant tissues. This difference is attributed to absorption of the emission by hemoglobin in normal tissues. This method using 488nm fails to distinguish neoplastic tissue such as benign tissues and tumors from malignant tumors. The time-resolved fluorescence at visible, near -uv and uv excitation wavelengths display non-exponential profiles which are significantly different for malignant tumors as compared to non-malignant tissues only with uv excitation. The differences observed with visible and near-uv excitation wavelengths are not as significant. The non-exponential profiles are interpreted as due to a combination of fluorophores along with the action of non-radiative processes. Low temperature luminescence studies confirm the occurrence of non-radiative decay processes while temporal studies of various relevant biomolecules indicate the probable fluorophores responsible for the observed signal in tissues. Phosphorescence from human tissues have been observed for the first time and lifetimes of a few hundred nanoseconds are measured for malignant and benign tissues. Time-resolved fluorescence studies of normal artery and atherosclerotic plaque have shown that a combination of two excitation wavelengths can distinguish fibrous and calcified atherosclerotic plaque from normal artery. A minor effort of the study involves the high intensity effects on the optical properties of the dye, doxycycline (a particular photosensitizer of the tetracycline group) occurring during relaxation when excited at different laser intensities. This study has been performed by observing the fluorescence lifetimes and quantum yields of DOTC at different excitation intensities. The results obtained support the sequential excited state absorption model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heller, Forrest D.; Casella, Amanda J.; Lumetta, Gregg J.

A Lewis cell was designed and constructed for investigating solvent extraction systems by spectrophotometrically monitoring both the organic and aqueous phases in real time. This new Lewis cell was tested and shown to perform well compared to other previously reported Lewis cell designs. The advantage of the new design is that the spectroscopic measurement allows determination of not only metal ion concentrations, but also information regarding chemical speciation—information not available with previous Lewis cell designs. For convenience, the new Lewis cell design was dubbed COSMOFLEX (COntinuous Spectroscopic MOnitoring of Forrest’s Liquid-liquid EXtraction cell).

Single-pulse measurement of density and temperature in a turbulent, supersonic flow using UV laser spectroscopy

NASA Technical Reports Server (NTRS)

Fletcher, D. G.; Mckenzie, R. L.

1992-01-01

Nonintrusive measurements of density and temperature and their turbulent fluctuation levels have been obtained in the boundary layer of an unseeded, Mach 2 wind tunnel flow. The spectroscopic technique that was used to make the measurements is based on the combination of laser-induced oxygen fluorescence and Raman scattering by oxygen and nitrogen from the same laser pulse. Results from this demonstration experiment compare favorably with previous measurements obtained in the same facility from conventional probes and an earlier spectroscopic technique.

FT-IR and µ-IR characterization of HED meteorites in relation to infrared spectra of Vesta-like asteroids

NASA Astrophysics Data System (ADS)

Ferrari, M.; Dirri, F.; Palomba, E.; Stefani, S.; Longobardo, A.; Rotundi, A.

2017-09-01

We present the results of the FT-IR and µ-IR study of three Howardite-Eucrite-Diogenite meteorites (HEDs) compared to the spectroscopic data collected by VIR onboard Dawn spacecraft. The origin of this group of achondrites is thought to be linked to the asteroid 4 Vesta, hypothesis lately reinforced by the data provided by the Dawn mission.

Hippocampal 1H-MRSI in ecstasy users.

PubMed

Obergriesser, T; Ende, G; Braus, D F; Henn, F A

2001-06-01

In recent years the illicit drug ecstasy (MDMA, 3,4-methylenedioxymethamphetamine) has come into widespread use among young people. Despite clear evidence for the neurotoxic potential of MDMA in animals, corresponding evidence in humans is limited to indirect findings. In an exploratory study we compared the hippocampal 1H-MRSI (magnetic resonance spectroscopic imaging) spectra of five MDMA users with those of controls with no history of substance abuse. Although 1H

Core-core and core-valence correlation

NASA Technical Reports Server (NTRS)

Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

1988-01-01

The effect of 1s core correlation on properties and energy separations are analyzed using full configuration-interaction (FCI) calculations. The Be1S - 1P, the C 3P - 5S,m and CH(+) 1Sigma(+) - 1Pi separations, and CH(+) spectroscopic constants, dipole moment, and 1Sigma(+) - 1Pi transition dipole moment have been studied. The results of the FCI calculations are compared to those obtained using approximate methods.

Effect of Silver Nanoparticles on the Sorption Characteristics of La1 - x Ag x MnO3 ± y

NASA Astrophysics Data System (ADS)

Ostroushko, A. A.; Adamova, L. V.; Koveza, E. V.; Russkikh, O. V.; Kuznetsov, M. V.

2018-03-01

The effect silver nanoparticles have on the sorption characteristics of perovskite lanthanum manganite relative to methanol, benzene, and hexane vapors is studied by means of gravimetric equilibrium interval sorption. The state of silver particles is investigated using spectroscopic tools. Sorption data are compared to the catalytic activity in deep oxidation reactions of organic compounds over lanthanum manganite-based catalysts.

In Situ Raman Spectroscopic Study of Gypsum (CaSO4·2H2O) and Epsomite (MgSO4·7H2O) Dehydration Utilizing an Ultrasonic Levitator.

PubMed

Brotton, Stephen J; Kaiser, Ralf I

2013-02-21

We present an original apparatus combining an acoustic levitator and a pressure-compatible process chamber. To characterize in situ the chemical and physical modifications of a levitated, single particle while heated to well-defined temperatures using a carbon dioxide laser, the chamber is interfaced to a Raman spectroscopic probe. As a proof-of-concept study, by gradually increasing the heating temperature, we observed the variations in the Raman spectra as 150 μg of crystals of gypsum and epsomite were dehydrated in anhydrous nitrogen gas. We display spectra showing the decreasing intensities of the ν1 symmetric and ν3 asymmetric stretching modes of water with time and the simultaneous shift of the ν1(SO4(2-)) symmetric stretch mode to higher wavenumbers. Our results demonstrate that the new apparatus is well suited to study the dehydration of levitated species such as minerals and offers potential advantages compared with previous experiments on bulk samples.

Theoretical studies of the electronic spectrum of tellurium monosulfide.

PubMed

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

2013-08-01

Ab initio based multireference singles and doubles configuration interaction (MRDCI) study including spin-orbit coupling is carried out to explore the electronic structure and spectroscopic properties of tellurium monosulfide (TeS) molecule by employing relativistic effective core potentials (RECP) and suitable Gaussian basis sets of the constituent atoms. Potential energy curves correlating with the lowest and second dissociation limit are constructed and spectroscopic constants (T(e), r(e), and ω(e)) of several low-lying bound Λ-S electronic states up to 3.68 eV of energy are computed. The binding energies and electric dipole moments (μ(e)) of the ground and the low-lying excited Λ-S states are also computed. The effects of the spin-orbit coupling on the electronic spectrum of the species are studied in details and compared with the available data. The transition probabilities of some dipole-allowed and spin-forbidden transitions are computed and radiative lifetimes of some excited states at lowest vibrational level are estimated from the transition probability data. Copyright © 2013 Elsevier B.V. All rights reserved.

Spectroscopic techniques to study the immune response in human saliva

NASA Astrophysics Data System (ADS)

Nepomnyashchaya, E.; Savchenko, E.; Velichko, E.; Bogomaz, T.; Aksenov, E.

2018-01-01

Studies of the immune response dynamics by means of spectroscopic techniques, i.e., laser correlation spectroscopy and fluorescence spectroscopy, are described. The laser correlation spectroscopy is aimed at measuring sizes of particles in biological fluids. The fluorescence spectroscopy allows studying of the conformational and other structural changings in immune complex. We have developed a new scheme of a laser correlation spectrometer and an original signal processing algorithm. We have suggested a new fluorescence detection scheme based on a prism and an integrating pin diode. The developed system based on the spectroscopic techniques allows studies of complex process in human saliva and opens some prospects for an individual treatment of immune diseases.

Reduction and Reoxidation of Humic Acid: Influence on Spectroscopic Properties and Proton Binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurer, F.; Christl, I; Kretzschmar, R

2010-01-01

Previous studies on proton and metal binding to humic substances have not considered a potential influence of reduction and oxidation of functional groups. Therefore, we investigated how proton binding of a purified soil humic acid was affected by reduction. Reduction of the humic acid was carried out using an electrochemical cell that allowed us to measure the amounts of electrons and protons involved in reduction reactions. We further applied spectroscopic methods (UV-vis, fluorescence, FT-IR, C-1s NEXAFS) to detect possible chemical changes in the humic acid induced by reduction and reoxidation. The effect of reduction on proton binding was determined withmore » acid-base titrations in the pH range 4-10 under controlled redox conditions. During reduction, 0.54 mol kg{sup -1} protons and 0.55 mol kg{sup -1} electrons were transferred to humic acid. NICA-Donnan modeling revealed an equivalent increase in proton-reactive sites (0.52 mol kg{sup -1}) in the alkaline pH-range. Our results indicate that reduction of humic acid increased the amount of proton-reactive sites by 15% compared to the untreated state. Spectroscopic differences between the untreated and reduced humic acid were minor, apart from a lower UV-vis absorption of the reduced humic acid between 400 and 700 nm.« less

Spectroscopic investigation on cocrystal formation between adenine and fumaric acid based on infrared and Raman techniques

NASA Astrophysics Data System (ADS)

Du, Yong; Fang, Hong Xia; Zhang, Qi; Zhang, Hui Li; Hong, Zhi

2016-01-01

As an important component of double-stranded DNA, adenine has powerful hydrogen-bond capability, due to rich hydrogen bond donors and acceptors existing within its molecular structure. Therefore, it is easy to form cocrystal between adenine and other small molecules with intermolecular hydrogen-bond effect. In this work, cocrystal of adenine and fumaric acid has been characterized as model system by FT-IR and FT-Raman spectral techniques. The experimental results show that the cocrystal formed between adenine and fumaric acid possesses unique spectroscopical characteristic compared with that of starting materials. Density functional theory (DFT) calculation has been performed to optimize the molecular structures and simulate vibrational modes of adenine, fumaric acid and the corresponding cocrystal. Combining the theoretical and experimental vibrational results, the characteristic bands corresponding to bending and stretching vibrations of amino and carbonyl groups within cocrystal are shifted into lower frequencies upon cocrystal formation, and the corresponding bond lengths show some increase due to the effect of intermolecular hydrogen bonding. Different vibrational modes shown in the experimental spectra have been assigned based on the simulation DFT results. The study could provide experimental and theoretical benchmarks to characterize cocrystal formed between active ingredients and cocrystal formers and also the intermolecular hydrogen-bond effect within cocrystal formation process by vibrational spectroscopic techniques.

Interaction of Flavonoids from Woodwardia unigemmata with Bovine Serum Albumin (BSA): Application of Spectroscopic Techniques and Molecular Modeling Methods.

PubMed

Ma, Rui; Pan, Hong; Shen, Tao; Li, Peng; Chen, Yanan; Li, Zhenyu; Di, Xiaxia; Wang, Shuqi

2017-08-09

Phytochemical investigation on the methanol extract of Woodwardia unigemmata resulted in the isolation of seven flavonoids, including one new flavonol acylglycoside ( 1 ). The structures of these compounds were elucidated on the basis of extensive spectroscopic analysis and comparison of literature data. The multidrug resistance (MDR) reversing activity was evaluated for the isolated compounds using doxorubicin-resistant K562/A02 cells model. Compound 6 showed comparable MDR reversing effect to verapamil. Furthermore, the interaction between compounds and bovine serum albumin (BSA) was investigated by spectroscopic methods, including steady-state fluorescence, synchronous fluorescence, circular dichroism (CD) spectroscopies, and molecular docking approach. The experimental results indicated that the seven flavonoids bind to BSA by static quenching mechanisms. The negative ΔH and ΔS values indicated that van der Waals interactions and hydrogen bonds contributed in the binding of compounds 2 - 6 to BSA. In the case of compounds 1 and 7 systems, the hydrophobic interactions play a major role. The binding of compounds to BSA causes slight changes in the secondary structure of BSA. There are two binding sites of compound 6 on BSA and site I is the main site according to the molecular docking studies and the site marker competitive binding assay.

Quartz crystal microbalance with coupled spectroscopic ellipsometry-study of temperature-responsive polymer brush systems

NASA Astrophysics Data System (ADS)

Adam, Stefan; Koenig, Meike; Rodenhausen, Keith Brian; Eichhorn, Klaus-Jochen; Oertel, Ulrich; Schubert, Mathias; Stamm, Manfred; Uhlmann, Petra

2017-11-01

Using a combined setup of quartz crystal microbalance with dissipation monitoring together with spectroscopic ellipsometry, the thermo-responsive behavior of two different brush systems (poly(N-isopropyl acrylamide) and poly(2-oxazoline)s) was investigated and compared to the behavior of the free polymer in solution. Poly(2-oxazoline)s with three different hydrophilicities were prepared by changing the content of a hydrophilic comonomer. While both polymer types exhibit a sharp, discontinuous thermal transition in solution, in the brush state the transition gets broader in the case of poly(N-isopropyl acrylamide) and is transformed into a continuous transition for poly(2-oxazoline)s. The position of the transition in solution is influenced by the degree of hydrophilicity of the poly(2-oxazoline). The difference in areal mass detected by quartz crystal microbalance and by spectroscopic ellipsometry, has been attributed to the chain segment density profile of the polymer brushes. Applying this density profile information, for poly(N-isopropyl acrylamide) two different swelling stages could be identified, while for poly(2-oxazoline) the transition between a parabolic and more step-wise profile is found continuous. The different swelling characteristics were attributed to the different miscibility behavior types, with the brush state acting similar to a crosslinked system.

Raman microspectroscopy and FTIR crystallization studies of 2,4,6-TNT in soil

NASA Astrophysics Data System (ADS)

Manrique-Bastidas, Cesar A.; Mina, Nairmen; Castro, Miguel E.; Hernandez-Rivera, Samuel P.

2005-06-01

2,4,6-Trinitrotoluene is a high explosive used in manufacturing landmine, bombs, and other explosive devices. It has been the main source of contamination in groundwater, soil as a result of intentional or accidental releases at many places around the world. Crystallization of TNT in soil from TNT/methanol solutions was carried out and characterized using vibrational spectroscopy. TNT exhibits a series of characteristic bands that allow its detection when in soil. The spectroscopic signatures of neat TNT and TNT in soil samples were determined with Raman Microspectroscopy and Fourier Transform Infrared (FTIR) Microscopy. The spectroscopic signature of neat TNT is dominated by strong bands about 1380 and 2970 cm-1. The intensity and position of these bands are found remarkably different in soil samples spiked with TNT. The 1380 cm-1 band is split into a number of bands in that region. The 2970 cm-1 is reduced in intensity and new bands are observed at about 2880 cm-1. The results are consistent with a different chemical environment for TNT in soil as compared to neat TNT. Further measurements are required to fully understand the spectroscopic signature of TNT in soil samples. Its detection in soil is essential in landmine detection technology, and could address the improvement of the devices in the mentioned technology.

The 2003 edition of geisa: a spectroscopic database system for the second generation vertical sounders radiance simulation

NASA Astrophysics Data System (ADS)

Jacquinet-Husson, N.; Lmd Team

The GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) computer accessible database system, in its former 1997 and 2001 versions, has been updated in 2003 (GEISA-03). It is developed by the ARA (Atmospheric Radiation Analysis) group at LMD (Laboratoire de Météorologie Dynamique, France) since 1974. This early effort implemented the so-called `` line-by-line and layer-by-layer '' approach for forward radiative transfer modelling action. The GEISA 2003 system comprises three databases with their associated management softwares: a database of spectroscopic parameters required to describe adequately the individual spectral lines belonging to 42 molecules (96 isotopic species) and located in a spectral range from the microwave to the limit of the visible. The featured molecules are of interest in studies of the terrestrial as well as the other planetary atmospheres, especially those of the Giant Planets. a database of absorption cross-sections of molecules such as chlorofluorocarbons which exhibit unresolvable spectra. a database of refractive indices of basic atmospheric aerosol components. Illustrations will be given of GEISA-03, data archiving method, contents, management softwares and Web access facilities at: http://ara.lmd.polytechnique.fr The performance of instruments like AIRS (Atmospheric Infrared Sounder; http://www-airs.jpl.nasa.gov) in the USA, and IASI (Infrared Atmospheric Sounding Interferometer; http://smsc.cnes.fr/IASI/index.htm) in Europe, which have a better vertical resolution and accuracy, compared to the presently existing satellite infrared vertical sounders, is directly related to the quality of the spectroscopic parameters of the optically active gases, since these are essential input in the forward models used to simulate recorded radiance spectra. For these upcoming atmospheric sounders, the so-called GEISA/IASI sub-database system has been elaborated, from GEISA. Its content, will be described, as well. This work is ongoing, with the purpose of assessing the IASI measurements capabilities and the spectroscopic information quality, within the ISSWG (IASI Sounding Science Working Group), in the frame of the CNES (Centre National d'Etudes Spatiales, France)/EUMETSAT (EUropean organization for the exploitation of METeorological SATellites) Polar System (EPS) project, by simulating high resolution radiances and/or using experimental data. EUMETSAT will implement GEISA/IASI into the EPS ground segment. The IASI soundings spectroscopic data archive requirements will be discussed in the context of comparisons between recorded and calculated experimental spectra, using the ARA/4A forward line-by-line radiative transfer modelling code in its latest version.

Molecular weight, polydispersity, and spectroscopic properties of aquatic humic substances

USGS Publications Warehouse

Chin, Y.-P.; Aiken, G.; O'Loughlin, E.

1994-01-01

The number- and weight-averaged molecular weights of a number of aquatic fulvic acids, a commercial humic acid, and unfractionated organic matter from four natural water samples were measured by high-pressure size exclusion chromatography (HPSEC). Molecular weights determined in this manner compared favorably with those values reported in the literature. Both recent literature values and our data indicate that these substances are smaller and less polydisperse than previously believed. Moreover, the molecular weights of the organic matter from three of the four natural water samples compared favorably to the fulvic acid samples extracted from similar environments. Bulk spectroscopic properties of the fulvic substances such as molar absorptivity at 280 nm and the E4/E6 ratio were also measured. A strong correlation was observed between molar absorptivity, total aromaticity, and the weight average molecular weights of all the humic substances. This observation suggests that bulk spectroscopic properties can be used to quickly estimate the size of humic substances and their aromatic contents. Both parameters are important with respect to understanding humic substance mobility and their propensity to react with both organic and inorganic pollutants. ?? 1994 American Chemical Society.

Spectroscopic study of the microbial community in chemocline zones of relic meromictic lakes separating from the White Sea

NASA Astrophysics Data System (ADS)

Kharcheva, Anastasia V.; Krasnova, Elena D.; Voronov, Dmitry A.; Patsaeva, Svetlana V.

2015-03-01

As a result of a recent years study on the Karelia shore of the White Sea more than ten relict lakes in different stages of separation from the sea have been discovered. Five of them are located close to the Nikolai Pertsov White Sea Biological Station of Moscow State University. Such separated lakes are interesting to explore for their firm vertical stratification. Water layers differ not only by temperature, salinity and other physic and chemical characteristics and optical properties, but also by ibhabiting microorganisms and by the quality of dissolved organic matter. To study phototropic organisms in water sampled from different depths we used spectroscopic techniques. Identification of the main bands in the absorption and fluorescence spectra showed that there are two main groups of photosynthetic organisms in the redox zone (chemocline): unicellular algae containing chlorophyll a and green sulfur bacteria with bacteriochlorophylls c, d, e. Spectral data were compared with physical and chemical characteristics of the water layer (temperature, salinity, pH, dissolved oxygen and sunlight illumination at certain depth). It gave an opportunity to compare vertical profiles of oxygen and hydrogen sulphide concentration with the number and distribution of oxygenic and anoxygenic phototrophic microorganisms. Maximum abundance of both algae and green sulfur bacteria were achieved within the redox zone. Typical thickness of the layer with the highest concentration of microorganisms did not exceed 10-20 cm.

Luis W. Alvarez - Patents

Science.gov Websites

SPECTROSCOPIC SYSTEM COMPRISING PLURAL SOURCES, FILTERS, FLUORESCENT RADIATORS, AND COMPARATIVE DETECTORS the element to be determined. Details of the design of the apparatus are described and diagrammed

Experimental 64Zn(d⃗,t)63Zn spectroscopic factors: Guidance for isospin-symmetry-breaking calculations

NASA Astrophysics Data System (ADS)

Leach, K. G.; Garrett, P. E.; Towner, I. S.; Ball, G. C.; Bildstein, V.; Brown, B. A.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Krücken, R.; Phillips, A. A.; Rand, E. T.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wirth, H.-F.; Wong, J.

2013-06-01

With the recent inclusion of core orbitals to the radial-overlap component of the isospin-symmetry-breaking (ISB) corrections for superallowed Fermi β decay, experimental data are needed to test the validity of the theoretical model. This work reports measurements of single-neutron pickup reaction spectroscopic factors into 63Zn, one neutron away from 62Zn, the superallowed daughter of 62Ga. The experiment was performed using a 22-MeV polarized deuteron beam, a Q3D magnetic spectrograph, and a cathode-strip focal-plane detector to analyze outgoing tritons at nine angles between 10∘ and 60∘. Angular distributions and vector analyzing powers were obtained for all 162 observed states in 63Zn, including 125 newly observed levels, up to an excitation energy of 4.8 MeV. Spectroscopic factors are extracted and compared to several shell-model predictions, and implications for the ISB calculations are discussed.

T.D.S. spectroscopic databank for spherical tops: DOS version

NASA Astrophysics Data System (ADS)

Tyuterev, V. G.; Babikov, Yu. L.; Tashkun, S. A.; Perevalov, V. I.; Nikitin, A.; Champion, J.-P.; Wenger, C.; Pierre, C.; Pierre, G.; Hilico, J.-C.; Loete, M.

1994-10-01

T.D.S. (Traitement de Donnees Spectroscopiques or Tomsk-Dijon-Spectroscopy project) is a computer package concerned with high resolution spectroscopy of spherical top molecules like CH4, CF4, SiH4, SiF4, SnH4, GeH4, SF6, etc. T.D.S. contains information, fundamental spectroscopic data (energies, transition moments, spectroscopic constants) recovered from comprehensive modeling and simultaneous fitting of experimental spectra, and associated software written in C. The T.D.S. goal is to provide an access to all available information on vibration-rotation molecular states and transitions including various spectroscopic processes (Stark, Raman, etc.) under extended conditions based on extrapolations of laboratory measurements using validated theoretical models. Applications for T.D.S. may include: education/training in molecular physics, quantum chemistry, laser physics; spectroscopic applications (analysis, laser spectroscopy, atmospheric optics, optical standards, spectroscopic atlases); applications to environment studies and atmospheric physics (remote sensing); data supply for specific databases; and to photochemistry (laser excitation, multiphoton processes). The reported DOS-version is designed for IBM and compatible personal computers.

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

NASA Astrophysics Data System (ADS)

Jang, Albert Woo Ju

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

Hyperspectral laser-induced autofluorescence imaging of dental caries

NASA Astrophysics Data System (ADS)

Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

2012-01-01

Dental caries is a disease characterized by demineralization of enamel crystals leading to the penetration of bacteria into the dentine and pulp. Early detection of enamel demineralization resulting in increased enamel porosity, commonly known as white spots, is a difficult diagnostic task. Laser induced autofluorescence was shown to be a useful method for early detection of demineralization. The existing studies involved either a single point spectroscopic measurements or imaging at a single spectral band. In the case of spectroscopic measurements, very little or no spatial information is acquired and the measured autofluorescence signal strongly depends on the position and orientation of the probe. On the other hand, single-band spectral imaging can be substantially affected by local spectral artefacts. Such effects can significantly interfere with automated methods for detection of early caries lesions. In contrast, hyperspectral imaging effectively combines the spatial information of imaging methods with the spectral information of spectroscopic methods providing excellent basis for development of robust and reliable algorithms for automated classification and analysis of hard dental tissues. In this paper, we employ 405 nm laser excitation of natural caries lesions. The fluorescence signal is acquired by a state-of-the-art hyperspectral imaging system consisting of a high-resolution acousto-optic tunable filter (AOTF) and a highly sensitive Scientific CMOS camera in the spectral range from 550 nm to 800 nm. The results are compared to the contrast obtained by near-infrared hyperspectral imaging technique employed in the existing studies on early detection of dental caries.

Unbiased Large Spectroscopic Surveys of Galaxies Selected by SPICA Using Dust Bands

NASA Astrophysics Data System (ADS)

Kaneda, H.; Ishihara, D.; Oyabu, S.; Yamagishi, M.; Wada, T.; Armus, L.; Baes, M.; Charmandaris, V.; Czerny, B.; Efstathiou, A.; Fernández-Ontiveros, J. A.; Ferrara, A.; González-Alfonso, E.; Griffin, M.; Gruppioni, C.; Hatziminaoglou, E.; Imanishi, M.; Kohno, K.; Kwon, J.; Nakagawa, T.; Onaka, T.; Pozzi, F.; Scott, D.; Smith, J.-D. T.; Spinoglio, L.; Suzuki, T.; van der Tak, F.; Vaccari, M.; Vignali, C.; Wang, L.

2017-11-01

The mid-infrared range contains many spectral features associated with large molecules and dust grains such as polycyclic aromatic hydrocarbons and silicates. These are usually very strong compared to fine-structure gas lines, and thus valuable in studying the spectral properties of faint distant galaxies. In this paper, we evaluate the capability of low-resolution mid-infrared spectroscopic surveys of galaxies that could be performed by SPICA. The surveys are designed to address the question how star formation and black hole accretion activities evolved over cosmic time through spectral diagnostics of the physical conditions of the interstellar/circumnuclear media in galaxies. On the basis of results obtained with Herschel far-infrared photometric surveys of distant galaxies and Spitzer and AKARI near- to mid-infrared spectroscopic observations of nearby galaxies, we estimate the numbers of the galaxies at redshift z > 0.5, which are expected to be detected in the polycyclic aromatic hydrocarbon features or dust continuum by a wide (10 deg2) or deep (1 deg2) blind survey, both for a given observation time of 600 h. As by-products of the wide blind survey, we also expect to detect debris disks, through the mid-infrared excess above the photospheric emission of nearby main-sequence stars, and we estimate their number. We demonstrate that the SPICA mid-infrared surveys will efficiently provide us with unprecedentedly large spectral samples, which can be studied further in the far-infrared with SPICA.

Pectin functionalised by fatty acids: Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic characterisation

NASA Astrophysics Data System (ADS)

Kamnev, Alexander A.; Calce, Enrica; Tarantilis, Petros A.; Tugarova, Anna V.; De Luca, Stefania

2015-01-01

Chemically modified pectin derivatives obtained by partial esterification of its hydroxyl moieties with fatty acids (FA; oleic, linoleic and palmitic acids), as well as the initial apple peel pectin were comparatively characterised using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Characteristic changes observed in DRIFT spectra in going from pectin to its FA esters are related to the corresponding chemical modifications. Comparing the DRIFT spectra with some reported data on FTIR spectra of the same materials measured in KBr or NaCl matrices has revealed noticeable shifts of several polar functional groups both in pectin and in its FA-esterified products induced by the halide salts. The results obtained have implications for careful structural analyses of biopolymers with hydrophilic functional groups by means of different FTIR spectroscopic methodologies.

Structural transformation of synthetic hydroxyapatite under simulated in vivo conditions studied with ATR-FTIR spectroscopic imaging

NASA Astrophysics Data System (ADS)

Sroka-Bartnicka, Anna; Borkowski, Leszek; Ginalska, Grazyna; Ślósarczyk, Anna; Kazarian, Sergei G.

2017-01-01

Hydroxyapatite and carbonate-substituted hydroxyapatite are widely used in bone tissue engineering and regenerative medicine. Both apatite materials were embedded into recently developed ceramic/polymer composites, subjected to Simulated Body Fluid (SBF) for 30 days and characterized using ATR-FTIR spectroscopic imaging to assess their behaviour and structures. The specific aim was to detect the transition phases between both types of hydroxyapatite during the test and to analyze the surface modification caused by SBF. ATR-FTIR spectroscopic imaging was successfully applied to characterise changes in the hydroxyapatite lattice due to the elastic properties of the scaffolds. It was observed that SBF treatment caused a replacement of phosphates in the lattice of non-substituted hydroxyapatite by carbonate ions. A detailed study excluded the formation of pure A type carbonate apatite. In turn, CO32- content in synthetic carbonate-substituted hydroxyapatite decreased. The usefulness of ATR-FTIR spectroscopic imaging studies in the evaluation of elastic and porous β-glucan hydroxyapatite composites has been demonstrated.

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

PubMed

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

2012-02-01

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

Chemical Abundances of Metal-poor RR Lyrae Stars in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Haschke, Raoul; Grebel, Eva K.; Frebel, Anna; Duffau, Sonia; Hansen, Camilla J.; Koch, Andreas

2012-09-01

We present for the first time a detailed spectroscopic study of chemical element abundances of metal-poor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R ~ 2000-6000) spectra of six RR Lyrae stars in the LMC and three RR Lyrae stars in the SMC. These stars were chosen because their previously determined photometric metallicities were among the lowest metallicities found for stars belonging to the old populations in the Magellanic Clouds. We find the spectroscopic metallicities of these stars to be as low as [Fe/H]spec = -2.7 dex, the lowest metallicity yet measured for any star in the Magellanic Clouds. We confirm that for metal-poor stars, the photometric metallicities from the Fourier decomposition of the light curves are systematically too high compared to their spectroscopic counterparts. However, for even more metal-poor stars below [Fe/H]phot < -2.8 dex this trend is reversed and the spectroscopic metallicities are systematically higher than the photometric estimates. We are able to determine abundance ratios for 10 chemical elements (Fe, Na, Mg, Al, Ca, Sc, Ti, Cr, Sr, and Ba), which extend the abundance measurements of chemical elements for RR Lyrae stars in the Clouds beyond [Fe/H] for the first time. For the overall [α/Fe] ratio, we obtain an overabundance of 0.36 dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. Comparing the abundances with those of the stars in the Milky Way halo we find that the abundance ratios of stars of both populations are consistent with another. Therefore, we conclude that from a chemical point of view early contributions from Magellanic-type galaxies to the formation of the Galactic halo as claimed in cosmological models are plausible. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

Preliminary evaluation of hydrocarbon removal power of Caulerpa racemosa in seawater by means of infrared and visible spectroscopic measurements.

PubMed

Pietroletti, Marco; Capobianchi, Alfredo; Ragosta, Emanuela; Mecozzi, Mauro

2010-10-15

In this paper we tested the power of Caulerpa racemosa for removal hydrocarbons from seawater. C. racemosa was implanted in two aquariums filled with natural seawater having a hydrocarbon content lower than 0.05mg/L which is the detection limit of the FTIR spectrophotometric method used for the determination. One aquarium was submitted to sequential additions of hydrocarbons (n-esadecane 10, 20 and 40mg/L, n-docosane 15mg/L) and diesel fuels (20mg/L) while the second one remained uncontaminated and used as control. After any addition, hydrocarbon content in seawater was determined at regular time intervals (one or two days) and when comparable hydrocarbon contents (i.e. lower than 0.05mg/L) were again observed, the real removal power of hydrocarbons was verified by several spectroscopic measurements performed on algae from both aquariums. Total hydrocarbon contents in algae determined by infrared (FTIR) spectroscopy, always resulted higher in the polluted aquarium for all the concentrations of added pollutants. Further FTIR studies performed on algae showed the presence of marked quantitative and structural molecular modifications involving carbohydrates, proteins, lipids, nucleic acids and chlorophyll pigments in C. racemosa from the aquarium test. In addition, visible (VIS) spectroscopic examination of C. racemosa showed a reduction of chlorophyll pigments in the polluted aquarium with respect to the control one. At last, FTIR spectra all the algal samples submitted to hydrocarbon pollution were re-examined by means of two-dimensional correlation analysis, a statistical tool helpful for studying the dynamic evolution of any molecular and biological system submitted to an external perturbation producing compositional and structural changes. This approach showed differences among the molecular modifications caused by any type of hydrocarbon used, modifications related reasonably to the molecular dimensions and concentration of the added pollutants. All these spectroscopic evidences suggested that the removal power of C. racemosa depends on its metabolic activities and not only on a simple adsorption process.

Theoretical investigation of electronic states and spectroscopic properties of tellurium selenide molecule employing relativistic effective core potentials.

PubMed

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

2014-04-24

Ab initio based relativistic configuration interaction calculations have been performed to study the electronic states and spectroscopic properties of tellurium selenide (TeSe) - the heaviest heteronuclear diatomic group 16-16 molecule. Potential energy curves of several spin-excluded (Λ-S) electronic states of TeSe have been constructed and spectroscopic constants of low-lying bound Λ-S states within 3.85 eV are reported in the first stage of calculations. The X(3)Σ(-), a(1)Δ and b(1)Σ(+) are found as the ground, first excited and second excited state, respectively, at the Λ-S level and all these three states are mainly dominated by …π(4)π(*2) configuration. The computed ground state dissociation energy is in very good agreement with the experimental results. In the next stage of calculations, effects of spin-orbit coupling on the potential energy curves and spectroscopic properties of the species are investigated in details and compared with the existing experimental results. After inclusion of spin-orbit coupling the X(3)(1)Σ(-)(0(+)) is found as the ground-state spin component of TeSe. The computed spin-orbit splitting between two components of X(3)Σ(-) state is 1285 cm(-1). Also, significant amount of spin-orbit splitting are found between spin-orbit components (Ω-components) of several other excited states. Transition moments of some important spin-allowed and spin-forbidden transitions are calculated from configuration interaction wave functions. The spin-allowed transition B(3)Σ(-)-X(3)Σ(-) and spin-forbidden transition b(1)Σ(+)(0(+))-X(3)(1)Σ(-)(0(+)) are found to be the strongest in their respective categories. Electric dipole moments of all the bound Λ-S states along with those of the two Ω-components of X(3)Σ(-) are also calculated in the present study. Copyright © 2014 Elsevier B.V. All rights reserved.

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

PubMed

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

2015-01-01

Violacein is a bisindole pigment occurring as a biosynthetic product of Chromobacterium violaceum and Janthinobacterium lividum. It has some structural similarities to the cyanobacterial UV-protective pigment scytonemin, which has been the subject of comprehensive spectroscopic and structural studies. A detailed experimental Raman spectroscopic study with visible and near-infrared excitation of violacein produced by C. violaceum has been undertaken and supported using theoretical DFT calculations. Raman spectra with 514 and 785 nm excitation of cultivated cells as well as extracts and Gaussian (B3LYP/6-311++G(d,p)) calculations with proposed molecular vibrational assignments are reported here. Copyright © 2015 Elsevier B.V. All rights reserved.

In vivo spectroscopic photoacoustic tomography imaging of a far red fluorescent protein expressed in the exocrine pancreas of adult zebrafish

NASA Astrophysics Data System (ADS)

Liu, Mengyang; Schmitner, Nicole; Sandrian, Michelle G.; Zabihian, Behrooz; Hermann, Boris; Salvenmoser, Willi; Meyer, Dirk; Drexler, Wolfgang

2014-03-01

Fluorescent proteins brought a revolution in life sciences and biological research in that they make a powerful tool for researchers to study not only the structural and morphological information, but also dynamic and functional information in living cells and organisms. While green fluorescent proteins (GFP) have become a common labeling tool, red-shifted or even near infrared fluorescent proteins are becoming the research focus due to the fact that longer excitation wavelengths are more suitable for deep tissue imaging. In this study, E2-Crimson, a far red fluorescent protein whose excitation wavelength is 611 nm, was genetically expressed in the exocrine pancreas of adult zebrafish. Using spectroscopic all optical detection photoacoustic tomography, we mapped the distribution of E2-Crimson in 3D after imaging the transgenic zebrafish in vivo using two different wavelengths. With complementary morphological information provided by imaging the same fish using a spectral domain optical coherence tomography system, the E2-Crimson distribution acquired from spectroscopic photoacoustic tomography was confirmed in 2D by epifluorescence microscopy and in 3D by histology. To the authors' knowledge, this is the first time a far red fluorescent protein is imaged in vivo by spectroscopic photoacoustic tomography. Due to the regeneration feature of zebrafish pancreas, this work preludes the longitudinal studies of animal models of diseases such as pancreatitis by spectroscopic photoacoustic tomography. Since the effective penetration depth of photoacoustic tomography is beyond the transport mean free path length, other E2-Crimson labeled inner organs will also be able to be studied dynamically using spectroscopic photoacoustic tomography.

The Grism Lens-amplified Survey from Space (GLASS). IV. Mass Reconstruction of the Lensing Cluster Abell 2744 from Frontier Field Imaging and GLASS Spectroscopy

NASA Astrophysics Data System (ADS)

Wang, X.; Hoag, A.; Huang, K.-H.; Treu, T.; Bradač, M.; Schmidt, K. B.; Brammer, G. B.; Vulcani, B.; Jones, T. A.; Ryan, R. E., Jr.; Amorín, R.; Castellano, M.; Fontana, A.; Merlin, E.; Trenti, M.

2015-09-01

We present a strong and weak lensing reconstruction of the massive cluster Abell 2744, the first cluster for which deep Hubble Frontier Fields (HFF) images and spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) are available. By performing a targeted search for emission lines in multiply imaged sources using the GLASS spectra, we obtain five high-confidence spectroscopic redshifts and two tentative ones. We confirm one strongly lensed system by detecting the same emission lines in all three multiple images. We also search for additional line emitters blindly and use the full GLASS spectroscopic catalog to test reliability of photometric redshifts for faint line emitters. We see a reasonable agreement between our photometric and spectroscopic redshift measurements, when including nebular emission in photometric redshift estimations. We introduce a stringent procedure to identify only secure multiple image sets based on colors, morphology, and spectroscopy. By combining 7 multiple image systems with secure spectroscopic redshifts (at 5 distinct redshift planes) with 18 multiple image systems with secure photometric redshifts, we reconstruct the gravitational potential of the cluster pixellated on an adaptive grid, using a total of 72 images. The resulting mass map is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data to study the relative distribution of stars and dark matter in the cluster. We find that the stellar to total mass ratio varies substantially across the cluster field, suggesting that stars do not trace exactly the total mass in this interacting system. The maps of convergence, shear, and magnification are made available in the standard HFF format.

Accelerated echo planar J-resolved spectroscopic imaging in prostate cancer: a pilot validation of non-linear reconstruction using total variation and maximum entropy.

PubMed

Nagarajan, Rajakumar; Iqbal, Zohaib; Burns, Brian; Wilson, Neil E; Sarma, Manoj K; Margolis, Daniel A; Reiter, Robert E; Raman, Steven S; Thomas, M Albert

2015-11-01

The overlap of metabolites is a major limitation in one-dimensional (1D) spectral-based single-voxel MRS and multivoxel-based MRSI. By combining echo planar spectroscopic imaging (EPSI) with a two-dimensional (2D) J-resolved spectroscopic (JPRESS) sequence, 2D spectra can be recorded in multiple locations in a single slice of prostate using four-dimensional (4D) echo planar J-resolved spectroscopic imaging (EP-JRESI). The goal of the present work was to validate two different non-linear reconstruction methods independently using compressed sensing-based 4D EP-JRESI in prostate cancer (PCa): maximum entropy (MaxEnt) and total variation (TV). Twenty-two patients with PCa with a mean age of 63.8 years (range, 46-79 years) were investigated in this study. A 4D non-uniformly undersampled (NUS) EP-JRESI sequence was implemented on a Siemens 3-T MRI scanner. The NUS data were reconstructed using two non-linear reconstruction methods, namely MaxEnt and TV. Using both TV and MaxEnt reconstruction methods, the following observations were made in cancerous compared with non-cancerous locations: (i) higher mean (choline + creatine)/citrate metabolite ratios; (ii) increased levels of (choline + creatine)/spermine and (choline + creatine)/myo-inositol; and (iii) decreased levels of (choline + creatine)/(glutamine + glutamate). We have shown that it is possible to accelerate the 4D EP-JRESI sequence by four times and that the data can be reliably reconstructed using the TV and MaxEnt methods. The total acquisition duration was less than 13 min and we were able to detect and quantify several metabolites. Copyright © 2015 John Wiley & Sons, Ltd.

Deriving temperature, mass, and age of evolved stars from high-resolution spectra. Application to field stars and the open cluster IC 4651

NASA Astrophysics Data System (ADS)

Biazzo, K.; Pasquini, L.; Girardi, L.; Frasca, A.; da Silva, L.; Setiawan, J.; Marilli, E.; Hatzes, A. P.; Catalano, S.

2007-12-01

Aims:We test our capability of deriving stellar physical parameters of giant stars by analysing a sample of field stars and the well studied open cluster IC 4651 with different spectroscopic methods. Methods: The use of a technique based on line-depth ratios (LDRs) allows us to determine with high precision the effective temperature of the stars and to compare the results with those obtained with a classical LTE abundance analysis. Results: (i) For the field stars we find that the temperatures derived by means of the LDR method are in excellent agreement with those found by the spectral synthesis. This result is extremely encouraging because it shows that spectra can be used to firmly derive population characteristics (e.g., mass and age) of the observed stars. (ii) For the IC 4651 stars we use the determined effective temperature to derive the following results. a) The reddening E(B-V) of the cluster is 0.12±0.02, largely independent of the color-temperature calibration used. b) The age of the cluster is 1.2±0.2 Gyr. c) The typical mass of the analysed giant stars is 2.0±0.2~M⊙. Moreover, we find a systematic difference of about 0.2 dex in log g between spectroscopic and evolutionary values. Conclusions: We conclude that, in spite of known limitations, a classical spectroscopic analysis of giant stars may indeed result in very reliable stellar parameters. We caution that the quality of the agreement, on the other hand, depends on the details of the adopted spectroscopic analysis. Based on observations collected at the ESO telescopes at the Paranal and La Silla Observatories, Chile.

THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). IV. MASS RECONSTRUCTION OF THE LENSING CLUSTER ABELL 2744 FROM FRONTIER FIELD IMAGING AND GLASS SPECTROSCOPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X.; Schmidt, K. B.; Jones, T. A.

2015-09-20

We present a strong and weak lensing reconstruction of the massive cluster Abell 2744, the first cluster for which deep Hubble Frontier Fields (HFF) images and spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) are available. By performing a targeted search for emission lines in multiply imaged sources using the GLASS spectra, we obtain five high-confidence spectroscopic redshifts and two tentative ones. We confirm one strongly lensed system by detecting the same emission lines in all three multiple images. We also search for additional line emitters blindly and use the full GLASS spectroscopic catalog to test reliability of photometricmore » redshifts for faint line emitters. We see a reasonable agreement between our photometric and spectroscopic redshift measurements, when including nebular emission in photometric redshift estimations. We introduce a stringent procedure to identify only secure multiple image sets based on colors, morphology, and spectroscopy. By combining 7 multiple image systems with secure spectroscopic redshifts (at 5 distinct redshift planes) with 18 multiple image systems with secure photometric redshifts, we reconstruct the gravitational potential of the cluster pixellated on an adaptive grid, using a total of 72 images. The resulting mass map is compared with a stellar mass map obtained from the deep Spitzer Frontier Fields data to study the relative distribution of stars and dark matter in the cluster. We find that the stellar to total mass ratio varies substantially across the cluster field, suggesting that stars do not trace exactly the total mass in this interacting system. The maps of convergence, shear, and magnification are made available in the standard HFF format.« less

The Grism Lens-Amplified Survey from Space (GLASS). VI. Comparing the Mass and Light in MACS J0416.1-2403 Using Frontier Field Imaging and GLASS Spectroscopy

NASA Astrophysics Data System (ADS)

Hoag, A.; Huang, K.-H.; Treu, T.; Bradač, M.; Schmidt, K. B.; Wang, X.; Brammer, G. B.; Broussard, A.; Amorin, R.; Castellano, M.; Fontana, A.; Merlin, E.; Schrabback, T.; Trenti, M.; Vulcani, B.

2016-11-01

We present a model using both strong and weak gravitational lensing of the galaxy cluster MACS J0416.1-2403, constrained using spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS) and Hubble Frontier Fields (HFF) imaging data. We search for emission lines in known multiply imaged sources in the GLASS spectra, obtaining secure spectroscopic redshifts of 30 multiple images belonging to 15 distinct source galaxies. The GLASS spectra provide the first spectroscopic measurements for five of the source galaxies. The weak lensing signal is acquired from 884 galaxies in the F606W HFF image. By combining the weak lensing constraints with 15 multiple image systems with spectroscopic redshifts and nine multiple image systems with photometric redshifts, we reconstruct the gravitational potential of the cluster on an adaptive grid. The resulting map of total mass density is compared with a map of stellar mass density obtained from the deep Spitzer Frontier Fields imaging data to study the relative distribution of stellar and total mass in the cluster. We find that the projected stellar mass to total mass ratio, f ⋆, varies considerably with the stellar surface mass density. The mean projected stellar mass to total mass ratio is < {f}\\star > =0.009+/- 0.003 (stat.), but with a systematic error as large as 0.004-0.005, dominated by the choice of the initial mass function. We find agreement with several recent measurements of f ⋆ in massive cluster environments. The lensing maps of convergence, shear, and magnification are made available to the broader community in the standard HFF format.

How much can we trust high-resolution spectroscopic stellar chemical abundances?

NASA Astrophysics Data System (ADS)

Blanco-Cuaresma, S.; Nordlander, T.; Heiter, U.; Jofré, P.; Masseron, T.; Casamiquela, L.; Tabernero, H. M.; Bhat, S. S.; Casey, A. R.; Meléndez, J.; Ramírez, I.

2017-03-01

To study stellar populations, it is common to combine chemical abundances from different spectroscopic surveys/studies where different setups were used. These inhomogeneities can lead us to inaccurate scientific conclusions. In this work, we studied one aspect of the problem: When deriving chemical abundances from high-resolution stellar spectra, what differences originate from the use of different radiative transfer codes?

Fourier transform infrared and Raman spectroscopic characterization of homogeneous solution concentration gradients near a container wall at different temperatures

NASA Technical Reports Server (NTRS)

Loo, B. H.; Burns, D. H.; Lee, Y. G. L.; Emerson, M. T.

1991-01-01

Fourier transform infrared (FTIR) and Raman spectroscopic techniques were used to study the solution concentration gradient in succino nitrile-rich and water-rich homogeneous solutions. The spectroscopic data shows significant concentration dependency. Although FTIR-attenuated total reflectance could not yield surface spectra since the evanescent infrared wave penetrated deep into the bulk solution, it showed that water-rich clusters were decreased at higher temperatures. This result is consistent with the calorimetric results reported earlier.

Quantum-mechanical calculations of magnesium aspartate arginine structure and spectroscopic characteristics

NASA Astrophysics Data System (ADS)

Marcoin, W.; Pasterny, K.; Wrzalik, R.

2005-05-01

Theoretical calculations of magnesium aspartate-arginine (Mg[Asp-Arg]) structure and spectroscopic characteristics have been performed in the gas phase with the GAUSSIAN 98 software package using density functional theory (DFT) at the B3PW91 level. The 6-31+G* basis set was selected due to their reasonable quality and size. The comparison with corresponding results for magnesium aspartate-glycine (Mg[Asp-Gly]) is presented. NMR and IR measurements were carried out and obtained experimental 1H and 13C chemical shifts and IR spectra are compared with calculated spectral parameters.

Development of bupivacaine decorated reduced graphene oxide and its local anesthetic effect-In vivo study.

PubMed

Zhang, Zhi; Zhang, Xin; Li, Aixiang; Ma, Chuangen

2018-03-01

The present works aims to develop bupivacaine modified reduced graphene oxide (BPV/RGO), and comparative evaluation of their anesthetic effect with free bupivacaine (BPV). The prepared BPV/RGO was studied by using various spectroscopic and microscopic characterization studies. In vitro drug release from BPV/RGO was studied using HPLC analysis. The cytotoxicity of BPV/RGO was studied against fibroblast (3T3) cells. In vivo evaluation of anesthetic effects was performed on animal models. BPV/RGO showed a prolonged in vitro release and lower cytotoxicity when compared to free BPV. Also, BPV/RGO showed a significantly prolonged analgesic effect when compared to free BPV. Further, the prepared BPV/RGO drug delivery system demonstrated to function as gifted to overcome the drawbacks of free BPV and other available drug delivery systems by prolonging the anesthetic effect with poor cytotoxicity. Copyright © 2018. Published by Elsevier B.V.

Cascaded systems analysis of charge sharing in cadmium telluride photon-counting x-ray detectors.

PubMed

Tanguay, Jesse; Cunningham, Ian A

2018-05-01

Single-photon-counting (SPC) and spectroscopic x-ray detectors are under development in academic and industry laboratories for medical imaging applications. The spatial resolution of SPC and spectroscopic x-ray detectors is an important design criterion. The purpose of this article was to extend the cascaded systems approach to include a description of the spatial resolution of SPC and spectroscopic x-ray imaging detectors. A cascaded systems approach was used to model reabsorption of characteristic x rays, Coulomb repulsion, and diffusion in SPC and spectroscopic x-ray detectors. In addition to reabsorption, diffusion, and Coulomb repulsion, the model accounted for x-ray conversion to electron-hole (e-h) pairs, integration of e-h pairs in detector elements, electronic noise, and energy thresholding. The probability density function (PDF) describing the number of e-h pairs was propagated through each stage of the model and was used to derive new theoretical expressions for the large-area gain and modulation transfer function (MTF) of CdTe SPC x-ray detectors, and the energy bin sensitivity functions and MTFs of CdTe spectroscopic detectors. Theoretical predictions were compared with the results of MATLAB-based Monte Carlo (MC) simulations and published data. Comparisons were also made with the MTF of energy-integrating systems. Under general radiographic conditions, reabsorption, diffusion, and Coulomb repulsion together artificially inflate count rates by 20% to 50%. For thicker converters (e.g. 1000 μm) and larger detector elements (e.g. 500 μm pixel pitch) these processes result in modest inflation (i.e. ∼10%) in apparent count rates. Our theoretical and MC analyses predict that SPC MTFs will be degraded relative to those of energy-integrating systems for fluoroscopic, general radiographic, and CT imaging conditions. In most cases, this degradation is modest (i.e., ∼10% at the Nyquist frequency). However, for thicker converters, the SPC MTF can be degraded by up to 25% at the Nyquist frequency relative to EI systems. Additionally, unlike EI systems, the MTF of spectroscopic systems is strongly dependent on photon energy, which results in energy-bin-dependent spatial resolution in spectroscopic systems. The PDF-transfer approach to modeling signal transfer through SPC and spectroscopic x-ray imaging systems provides a framework for understanding system performance. Application of this approach demonstrated that charge sharing artificially inflates the SPC image signal and degrades the MTF of SPC and spectroscopic systems relative to energy-integrating systems. These results further motivate the need for anticharge-sharing circuits to mitigate the effects of charge sharing on SPC and spectroscopic x-ray image quality. © 2018 American Association of Physicists in Medicine.

Quantitative fluorescence and elastic scattering tissue polarimetry using an Eigenvalue calibrated spectroscopic Mueller matrix system.

PubMed

Soni, Jalpa; Purwar, Harsh; Lakhotia, Harshit; Chandel, Shubham; Banerjee, Chitram; Kumar, Uday; Ghosh, Nirmalya

2013-07-01

A novel spectroscopic Mueller matrix system has been developed and explored for both fluorescence and elastic scattering polarimetric measurements from biological tissues. The 4 × 4 Mueller matrix measurement strategy is based on sixteen spectrally resolved (λ = 400 - 800 nm) measurements performed by sequentially generating and analyzing four elliptical polarization states. Eigenvalue calibration of the system ensured high accuracy of Mueller matrix measurement over a broad wavelength range, either for forward or backscattering geometry. The system was explored for quantitative fluorescence and elastic scattering spectroscopic polarimetric studies on normal and precancerous tissue sections from human uterine cervix. The fluorescence spectroscopic Mueller matrices yielded an interesting diattenuation parameter, exhibiting differences between normal and precancerous tissues.

Orbital parameters of the multiple system EM Boo

NASA Astrophysics Data System (ADS)

Özkardeş, B.; Bakış, H.; Bakış, V.

2018-02-01

EM Boo is a relatively bright (V = 8.98 mag.) and short orbital period (P⁓2.45 days) binary star member of the multiple system WDS J14485+2445AB. There is neither photometric nor spectroscopic study of the system in the literature. In this work, we obtained spectroscopic orbital parameters of the system from new high resolution spectroscopic observations made with échelle spectrograph attached to UBT60 telescope of Akdeniz University. The spectroscopic solution yielded the values K1 = 100.7±2.6 km/s, K2 = 120.1±2.6 km/s and Vγ = -14.6±3.1 km/s, and thus the mass ratio of the system q = 0.838±0.064.

Spectroscopic study of the effect of biological treatment on the humification process of sewage sludge

NASA Astrophysics Data System (ADS)

Polak, J.; Sułkowski, W. W.; Bartoszek, M.; Luty, A.; Pentak, D.; Sułkowska, A.

2007-05-01

In 2005 the treatment plant in Sosnowiec Zagórze was modernized and the processes of nitrification and denitrification were introduced. The study of the biological treatment influence on the course of the humification process was conducted for the sewage sludge received from each stage of sewage purification. The extracted humic-like substances (HA) were investigated by the use of the spectroscopic and analytical methods. The concentration of free radicals and the g-factor was determined with EPR, the presence of the characteristic functional groups was confirmed with IR spectroscopy, whereas the aromatisation of HA was estimated by 13C NMR method. The results obtained were compared with those for HA extracted from sewage sludge before modernization [1]. It was found that the processes of biological treatment have a significant influence on the changes of the chemical elements in the extracted HA. The HA obtained after modernization are nitrogen-rich (about 9%), in particular after the nitrification and denitrification processes. However, nitrification and denitrification processes only slightly affect the free radical concentration and the g-factor values.

Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach

NASA Astrophysics Data System (ADS)

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

2011-09-01

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

Computational and spectroscopic studies of a new Schiff base 3-hydroxy-4-methoxybenzylidene(2-hydroxyphenyl)amine and molecular structure of its corresponding zwitterionic form.

PubMed

Habibi, Mohammad Hossein; Shojaee, Elahe; Ranjbar, Mahnaz; Memarian, Hamid Reza; Kanayama, Akihiko; Suzuki, Takayoshi

2013-03-15

Computational and spectroscopic properties of a novel Schiff base compound, 3-hydroxy-4-methoxybenzylidene(2-hydroxyphenyl)amine were studied. The crystal structures of the title compound and its corresponding zwitterionic form were analyzed by X-ray diffraction. The presence of N-H, C-O and C=N stretching vibrations in IR spectrum strongly suggest that the title compound has zwitterionic form in the solid state. Molecular geometry of the title compound in the ground state has been calculated using the density functional method (DFT) at B3LYP 6-31++G(d,p) basis set and was compared with the experimental data. The calculated results of the title compound show that the optimized geometry can well reproduce the crystal structure. The molecule shows absorption bands at 345 and 363 nm in EtOH. The shoulder-shaped bands at 415 nm can be assigned to n→π(*) transitions. The absorption band is observed at 285 nm in EtOH corresponds to the π→π(*) transitions. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation into the interaction of losartan with human serum albumin and glycated human serum albumin by spectroscopic and molecular dynamics simulation techniques: A comparison study.

PubMed

Moeinpour, Farid; Mohseni-Shahri, Fatemeh S; Malaekeh-Nikouei, Bizhan; Nassirli, Hooriyeh

2016-09-25

The interaction between losartan and human serum albumin (HSA), as well as its glycated form (gHSA) was studied by multiple spectroscopic techniques and molecular dynamics simulation under physiological conditions. The binding information, including the binding constants, effective quenching constant and number of binding sites showed that the binding partiality of losartan to HSA was higher than to gHSA. The findings of three-dimensional fluorescence spectra demonstrated that the binding of losartan to HSA and gHSA would alter the protein conformation. The distances between Trp residue and the binding sites of the drug were evaluated on the basis of the Förster theory, and it was indicated that non-radiative energy transfer from HSA and gHSA to the losartan happened with a high possibility. According to molecular dynamics simulation, the protein secondary and tertiary structure changes were compared in HSA and gHSA for clarifying the obtained results. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Rapid, accurate, and comparative differentiation of clinically and industrially relevant microorganisms via multiple vibrational spectroscopic fingerprinting.

PubMed

Muhamadali, Howbeer; Subaihi, Abdu; Mohammadtaheri, Mahsa; Xu, Yun; Ellis, David I; Ramanathan, Rajesh; Bansal, Vipul; Goodacre, Royston

2016-08-15

Despite the fact that various microorganisms (e.g., bacteria, fungi, viruses, etc.) have been linked with infectious diseases, their crucial role towards sustaining life on Earth is undeniable. The huge biodiversity, combined with the wide range of biochemical capabilities of these organisms, have always been the driving force behind their large number of current, and, as of yet, undiscovered future applications. The presence of such diversity could be said to expedite the need for the development of rapid, accurate and sensitive techniques which allow for the detection, differentiation, identification and classification of such organisms. In this study, we employed Fourier transform infrared (FT-IR), Raman, and surface enhanced Raman scattering (SERS) spectroscopies, as molecular whole-organism fingerprinting techniques, combined with multivariate statistical analysis approaches for the classification of a range of industrial, environmental or clinically relevant bacteria (P. aeruginosa, P. putida, E. coli, E. faecium, S. lividans, B. subtilis, B. cereus) and yeast (S. cerevisiae). Principal components-discriminant function analysis (PC-DFA) scores plots of the spectral data collected from all three techniques allowed for the clear differentiation of all the samples down to sub-species level. The partial least squares-discriminant analysis (PLS-DA) models generated using the SERS spectral data displayed lower accuracy (74.9%) when compared to those obtained from conventional Raman (97.8%) and FT-IR (96.2%) analyses. In addition, whilst background fluorescence was detected in Raman spectra for S. cerevisiae, this fluorescence was quenched when applying SERS to the same species, and conversely SERS appeared to introduce strong fluorescence when analysing P. putida. It is also worth noting that FT-IR analysis provided spectral data of high quality and reproducibility for the whole sample set, suggesting its applicability to a wider range of samples, and perhaps the most suitable for the analysis of mixed cultures in future studies. Furthermore, our results suggest that while each of these spectroscopic approaches may favour different organisms (sample types), when combined, they would provide complementary and more in-depth knowledge (structural and/or metabolic state) of biological systems. To the best of our knowledge, this is the first time that such a comparative and combined spectroscopic study (using FT-IR, Raman and SERS) has been carried out on microbial samples.

Spectroscopic, electrochemical DNA binding and in vivo anti-inflammatory studies on newly synthesized Schiff bases of 4-aminophenazone.

PubMed

Arshad, Nasima; Ahmad, Mukhtar; Ashraf, Muhammad Zaman; Nadeem, Humaira

2014-09-05

4-Aminophenazone (Ap-1) Schiff bases i.e., 4-{(3,4,5-trimethoxybenzylidine) amino}phenazone (Ap-2), 4-{(2-chlorobenzylidine) amino}phenazone (Ap-3) and 4-{(4-chlorobenzylidine)amino} phenazone (Ap-4) were synthesized and characterized by different spectroscopic techniques. Interaction of these compounds with ds.DNA was investigated through UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry at stomach (4.7) and blood (7.4) pH under 37 °C (human body temperature). Instrumental findings were further quantified both kinetically and thermodynamically. Results obtained through these techniques inferred intercalative mode of binding of all the compounds with DNA. The binding constant data, "Kb", and free energy change, ΔG, indicated comparatively greater binding affinity and more spontaneity of binding of compounds with DNA at stomach pH (4.7), respectively. However, among these compounds, Ap-4 showed comparatively greater binding at both the pH. Formation of compound-DNA complex was further confirmed through the decrease in diffusion rates after the addition of DNA. The in vivo anti-inflammatory activity of the compounds was evaluated using the carrageenan-induced hind paw edema method. The results revealed that among all the compounds, Ap-4 showed greater percentage of edema inhibition compared to standard drug. Copyright © 2014 Elsevier B.V. All rights reserved.

THE NASA AMES PAH IR SPECTROSCOPIC DATABASE VERSION 2.00: UPDATED CONTENT, WEB SITE, AND ON(OFF)LINE TOOLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boersma, C.; Mattioda, A. L.; Allamandola, L. J.

A significantly updated version of the NASA Ames PAH IR Spectroscopic Database, the first major revision since its release in 2010, is presented. The current version, version 2.00, contains 700 computational and 75 experimental spectra compared, respectively, with 583 and 60 in the initial release. The spectra span the 2.5-4000 μm (4000-2.5 cm{sup -1}) range. New tools are available on the site that allow one to analyze spectra in the database and compare them with imported astronomical spectra as well as a suite of IDL object classes (a collection of programs utilizing IDL's object-oriented programming capabilities) that permit offline analysismore » called the AmesPAHdbIDLSuite. Most noteworthy among the additions are the extension of the computational spectroscopic database to include a number of significantly larger polycyclic aromatic hydrocarbons (PAHs), the ability to visualize the molecular atomic motions corresponding to each vibrational mode, and a new tool that allows one to perform a non-negative least-squares fit of an imported astronomical spectrum with PAH spectra in the computational database. Finally, a methodology is described in the Appendix, and implemented using the AmesPAHdbIDLSuite, that allows the user to enforce charge balance during the fitting procedure.« less

Single-Shot MR Spectroscopic Imaging with Partial Parallel Imaging

PubMed Central

Posse, Stefan; Otazo, Ricardo; Tsai, Shang-Yueh; Yoshimoto, Akio Ernesto; Lin, Fa-Hsuan

2010-01-01

An MR spectroscopic imaging (MRSI) pulse sequence based on Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI) is introduced that measures 2-dimensional metabolite maps in a single excitation. Echo-planar spatial-spectral encoding was combined with interleaved phase encoding and parallel imaging using SENSE to reconstruct absorption mode spectra. The symmetrical k-space trajectory compensates phase errors due to convolution of spatial and spectral encoding. Single-shot MRSI at short TE was evaluated in phantoms and in vivo on a 3 T whole body scanner equipped with 12-channel array coil. Four-step interleaved phase encoding and 4-fold SENSE acceleration were used to encode a 16×16 spatial matrix with 390 Hz spectral width. Comparison with conventional PEPSI and PEPSI with 4-fold SENSE acceleration demonstrated comparable sensitivity per unit time when taking into account g-factor related noise increases and differences in sampling efficiency. LCModel fitting enabled quantification of Inositol, Choline, Creatine and NAA in vivo with concentration values in the ranges measured with conventional PEPSI and SENSE-accelerated PEPSI. Cramer-Rao lower bounds were comparable to those obtained with conventional SENSE-accelerated PEPSI at the same voxel size and measurement time. This single-shot MRSI method is therefore suitable for applications that require high temporal resolution to monitor temporal dynamics or to reduce sensitivity to tissue movement. PMID:19097245

Ultrafast dynamics and excited state spectra of open-chain carotenoids at room and low temperatures.

PubMed

Niedzwiedzki, Dariusz; Koscielecki, Jeremy F; Cong, Hong; Sullivan, James O; Gibson, George N; Birge, Robert R; Frank, Harry A

2007-05-31

Many of the spectroscopic features and photophysical properties of carotenoids are explained using a three-state model in which the strong visible absorption of the molecules is associated with an S0 (1(1)Ag-) --> S2 (1(1)Bu+) transition, and the lowest lying singlet state, S1 (2(1)Ag-), is a state into which absorption from the ground state is forbidden by symmetry. However, semiempirical and ab initio quantum calculations have suggested additional excited singlet states may lie either between or in the vicinity of S1 (2(1)Ag-) and S2 (1(1)Bu+), and some ultrafast spectroscopic studies have reported evidence for these states. One such state, denoted S*, has been implicated as an intermediate in the depopulation of S2 (1(1)Bu+) and as a pathway for the formation of carotenoid triplet states in light-harvesting complexes. In this work, we present the results of an ultrafast, time-resolved spectroscopic investigation of a series of open-chain carotenoids derived from photosynthetic bacteria and systematically increasing in their number of pi-electron carbon-carbon double bonds (n). The molecules are neurosporene (n = 9), spheroidene (n = 10), rhodopin glucoside (n = 11), rhodovibrin (n = 12), and spirilloxanthin (n = 13). The molecules were studied in acetone and CS2 solvents at room temperature. These experiments explore the effect of solvent polarity and polarizability on the spectroscopic and kinetic behavior of the molecules. The molecules were also studied in ether/isopentane/ethanol (EPA) glasses at 77 K, in which the spectral resolution is greatly enhanced. Analysis of the data using global fitting techniques has revealed the ultrafast dynamics of the excited states and spectral changes associated with their decay, including spectroscopic features not previously reported. The data are consistent with S* being identified with a twisted conformational structure, the yield of which is increased in molecules having longer pi-electron conjugations. In particular, for the longest molecule in the series, spirilloxanthin, the experiments and a detailed quantum computational analysis reveal the presence of two S* states associated with relaxed S1 (2(1)Ag-) conformations involving nearly planar 6-s-cis and 6-s-trans geometries. We propose that in polar solvents, the ground state of spirilloxanthin takes on a corkscrew conformation that generates a net solute dipole moment while decreasing the cavity formation energy. Upon excitation and relaxation into the S1 (2(1)Ag-) state, the polyene unravels and flattens into a more planar geometry with comparable populations of 6-s-trans and 6-s-cis conformations.

The GEISA Spectroscopic Database as a Tool for Hyperspectral Earth' Tropospheric Remote Sensing Applications

NASA Astrophysics Data System (ADS)

Jacquinet-Husson, Nicole; Crépeau, Laurent; Capelle, Virginie; Scott, Noëlle; Armante, Raymond; Chédin, Alain

2010-05-01

Remote sensing of the terrestrial atmosphere has advanced significantly in recent years, and this has placed greater demands on the compilations in terms of accuracy, additional species, and spectral coverage. The successful performances of the new generation of hyperspectral Earth' atmospheric sounders like AIRS (Atmospheric Infrared Sounder -http://www-airs.jpl.nasa.gov/), in the USA, and IASI (Infrared Atmospheric Sounding Interferometer -http://earth-sciences.cnes.fr/IASI/) in Europe, which have a better vertical resolution and accuracy, compared to the previous satellite infrared vertical sounders, depend ultimately on the accuracy to which the spectroscopic parameters of the optically active gases are known, since they constitute an essential input to the forward radiative transfer models that are used to interpret their observations. In this context, the GEISA (1) (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) computer-accessible database, initiated in 1976, is continuously developed and maintained at LMD (Laboratoire de Météorologie Dynamique, France). The updated 2009 edition of GEISA (GEISA-09)is a system comprising three independent sub-databases devoted respectively to: line transition parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, the contents of which will be summarized, 50 molecules are involved in the line transition parameters sub-database, including 111 isotopes, for a total of 3,807,997 entries, in the spectral range from 10-6 to 35,877.031 cm-1. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI through the GEISA/IASI database derived from GEISA (2). Since the Metop (http://www.eumetsat.int) launch (October 19th 2006), GEISA/IASI is the reference spectroscopic database for the validation of the level-1 IASI data, using the 4A radiative transfer model (3) (4A/LMD http://ara.lmd.polytechnique.fr; 4A/OP co-developed by LMD and NOVELTIS -http://www.noveltis.fr/) with the support of CNES (2006). Special emphasize will be given to the description of GEISA/IASI. Spectroscopic parameters quality requirement will be discussed in the context of comparisons between observed or simulated Earth's atmosphere spectra. GEISA and GEISA/IASI are implemented on the CNES/CNRS Ether Products and Services Centre WEB site (http://ether.ipsl.jussieu.fr), where all archived spectroscopic data can be handled through general and user friendly associated management software facilities. More than 350 researchers are registered for on line use of GEISA. Refs: (1) Jacquinet-Husson N., N.A. Scott, A. Chédin,L. Crépeau, R. Armante, V. Capelle, J. Orphal, A. Coustenis, C. Boonne, N. Poulet-Crovisier, et al. THE GEISA SPECTROSCOPIC DATABASE: Current and future archive for Earth and planetary atmosphere studies. JQSRT 109 (2008) 1043-1059. (2) Jacquinet-Husson N., N.A. Scott, A. Chédin, K. Garceran, R. Armante, et al. The 2003 edition of the GEISA/IASI spectroscopic database. JQSRT 95 (2005)429-467. (3) Scott, N.A. and A. Chedin. A fast line-by-line method for atmospheric absorption computations: The Automatized Atmospheric Absorption Atlas. J. Appl. Meteor. 20 (1981)556-564.

Factors determining electrostatic fields in molecular dynamics simulations of the Ras/effector interface.

PubMed

Ensign, Daniel L; Webb, Lauren J

2011-12-01

Using molecular dynamics simulations, we explore geometric and physical factors contributing to calculated electrostatic fields at the binding surface of the GTPase Ras with a spectroscopically labeled variant of a downstream effector, the Ras-binding domain of Ral guanine nucleotide dissociation stimulator (RalGDS). A related system (differing by mutation of one amino acid) has been studied in our group using vibrational Stark effect spectroscopy, a technique sensitive to electrostatic fields. Electrostatic fields were computed using the AMBER 2003 force field and averaged over snapshots from molecular dynamics simulation. We investigate geometric factors by exploring how the orientation of the spectroscopic probe changes on Ras-effector binding. In addition, we explore the physical origin of electrostatic fields at our spectroscopic probe by comparing contributions to the field from discrete components of the system, such as explicit solvent, residues on the Ras surface, and residues on the RalGDS surface. These models support our experimental hypothesis that vibrational Stark shifts are caused by Ras binding to its effector and not the structural rearrangements of the effector surface or probe reorientation on Ras-effector binding, for at least some of our experimental probes. These calculations provide physical insight into the origin, magnitude, and importance of electrostatic fields in protein-protein interactions and suggest new experiments to probe the field's role in protein docking. Copyright © 2011 Wiley-Liss, Inc.

Spectroscopic investigation on cocrystal formation between adenine and fumaric acid based on infrared and Raman techniques.

PubMed

Du, Yong; Fang, Hong Xia; Zhang, Qi; Zhang, Hui Li; Hong, Zhi

2016-01-15

As an important component of double-stranded DNA, adenine has powerful hydrogen-bond capability, due to rich hydrogen bond donors and acceptors existing within its molecular structure. Therefore, it is easy to form cocrystal between adenine and other small molecules with intermolecular hydrogen-bond effect. In this work, cocrystal of adenine and fumaric acid has been characterized as model system by FT-IR and FT-Raman spectral techniques. The experimental results show that the cocrystal formed between adenine and fumaric acid possesses unique spectroscopical characteristic compared with that of starting materials. Density functional theory (DFT) calculation has been performed to optimize the molecular structures and simulate vibrational modes of adenine, fumaric acid and the corresponding cocrystal. Combining the theoretical and experimental vibrational results, the characteristic bands corresponding to bending and stretching vibrations of amino and carbonyl groups within cocrystal are shifted into lower frequencies upon cocrystal formation, and the corresponding bond lengths show some increase due to the effect of intermolecular hydrogen bonding. Different vibrational modes shown in the experimental spectra have been assigned based on the simulation DFT results. The study could provide experimental and theoretical benchmarks to characterize cocrystal formed between active ingredients and cocrystal formers and also the intermolecular hydrogen-bond effect within cocrystal formation process by vibrational spectroscopic techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

The application of visible absorption spectroscopy to the analysis of uranium in aqueous solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colletti, Lisa Michelle; Copping, Roy; Garduno, Katherine

Through assay analysis into an excess of 1 M H 2SO 4 at fixed temperature a technique has been developed for uranium concentration analysis by visible absorption spectroscopy over an assay concentration range of 1.8 – 13.4 mgU/g. Once implemented for a particular spectrophotometer and set of spectroscopic cells this technique promises to provide more rapid results than a classical method such as Davies-Gray (DG) titration analysis. While not as accurate and precise as the DG method, a comparative analysis study reveals that the spectroscopic method can analyze for uranium in well characterized uranyl(VI) solution samples to within 0.3% ofmore » the DG results. For unknown uranium solutions in which sample purity is less well defined agreement between the developed spectroscopic method and DG analysis is within 0.5%. The technique can also be used to detect the presence of impurities that impact the colorimetric analysis, as confirmed through the analysis of ruthenium contamination. Finally, extending the technique to other assay solution, 1 M HNO 3, HCl and Na 2CO 3, has also been shown to be viable. As a result, of the four aqueous media the carbonate solution yields the largest molar absorptivity value at the most intensely absorbing band, with the least impact of temperature.« less

The application of visible absorption spectroscopy to the analysis of uranium in aqueous solutions

DOE PAGES

Colletti, Lisa Michelle; Copping, Roy; Garduno, Katherine; ...

2017-07-18

Through assay analysis into an excess of 1 M H 2SO 4 at fixed temperature a technique has been developed for uranium concentration analysis by visible absorption spectroscopy over an assay concentration range of 1.8 – 13.4 mgU/g. Once implemented for a particular spectrophotometer and set of spectroscopic cells this technique promises to provide more rapid results than a classical method such as Davies-Gray (DG) titration analysis. While not as accurate and precise as the DG method, a comparative analysis study reveals that the spectroscopic method can analyze for uranium in well characterized uranyl(VI) solution samples to within 0.3% ofmore » the DG results. For unknown uranium solutions in which sample purity is less well defined agreement between the developed spectroscopic method and DG analysis is within 0.5%. The technique can also be used to detect the presence of impurities that impact the colorimetric analysis, as confirmed through the analysis of ruthenium contamination. Finally, extending the technique to other assay solution, 1 M HNO 3, HCl and Na 2CO 3, has also been shown to be viable. As a result, of the four aqueous media the carbonate solution yields the largest molar absorptivity value at the most intensely absorbing band, with the least impact of temperature.« less

Molecular Gas Content of an Extremely Star-forming Herschel Observed Lensed Dusty Galaxy at z=2.685

NASA Astrophysics Data System (ADS)

Nayyeri, Hooshang; Cooray, Asantha R.; H-ATLAS

2017-01-01

We present the results of combined deep near-infrared, far infrared and millimeter observations of an extremely star forming lensed dusty star-forming galaxy (DSFG) identified from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). The high redshift DSFG is gravitationally lensed by a massive WISE identified cluster at z~1 (spectroscopically confirmed with Keck/DEIMOS and Gemini/GMOS) producing multiply lensed images and arcs observed in the optical. The DSFG is spectroscopically confirmed at z=2.685 from CO(1-0) observations by GBT and separately from CO(3-2) observations by CARMA. We use the combined spectroscopic and imaging observations to construct a detailed lens model of the background DSFG which allowed us to study the sources plane properties of the target. Multi-band data from Keck/NIRC2, HST/WFC3 and Herschel yields star formation rate and stellar mass well above the main sequence. Observations of the dust continuum by the Sub-millimeter Array yields an observed total ISM mass of 6.5E+11 M* which is responsible for the intense observed star formation rates. Comparing the measured SFR with molecular gas measurements from CO(1-0) observations reveals that this system has relatively short gas depletion time scale which is consistent with the starburst phase observed in high redshift sub-millimeter galaxies.

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

NASA Technical Reports Server (NTRS)

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

1975-01-01

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

Models of red giants in the CoRoT asteroseismology fields combining asteroseismic and spectroscopic constraints - The open cluster NGC 6633 and field stars-

NASA Astrophysics Data System (ADS)

Lagarde, Nadège; Miglio, Andrea; Eggenberger, Patrick; Morel, Thierry; Montalbàn, Josefina; Mosser, Benoit

2015-08-01

The availability of asteroseismic constraints for a large sample of red giant stars from the CoRoT and Kepler missions paves the way for various statistical studies of the seismic properties of stellar populations.We use the first detailed spectroscopic study of CoRoT red-giant stars (Morel et al 2014) to compare theoretical stellar evolution models to observations of the open cluster NGC 6633 and field stars.In order to explore the effects of rotation-induced mixing and thermohaline instability, we compare surface abundances of carbon isotopic ratio and lithium with stellar evolution predictions. These chemicals are sensitive to extra-mixing on the red-giant branch.We estimate mass, radius, and distance for each star using the seismic constraints. We note that the Hipparcos and seismic distances are different. However, the uncertainties are such that this may not be significant. Although the seismic distances for the cluster members are self consistent they are somewhat larger than the Hipparcos distance. This is an issue that should be considered elsewhere. Models including thermohaline instability and rotation-induced mixing, together with the seismically determined masses can explain the chemical properties of red-giants targets. Tighter constraints on the physics of the models would be possible if there were detailed knowledge of the core rotation rate and the asymptotic period spacing.

Excited-State Dynamics of Biological Molecules in Solution: Photoinduced Charge Transfer in Oxidatively Damaged DNA and Deactivation of Violacein in Viscous Solvents

NASA Astrophysics Data System (ADS)

Beckstead, Ashley Ann

UV radiation from the sun is strongly absorbed by DNA, and the resulting electronic excited states can lead to the formation of mutagenic photoproducts. Decades of research have brought to light the excited-state dynamics of single RNA and DNA nucleobases, but questions remain about the nature of excited states accessed in DNA strands. In this thesis, I present ultrafast spectroscopic observations of photoinduced electron transfer from the oxidatively damaged bases, 8-oxo-7,8-dihydro-2'-deoxyguanosine, 5-hydroxy-2'-deoxycytidine and 5-hydroxy-2'-deoxyuridine, to adenine in three dinucleotides. The results reveal that charge transfer states are formed on a timescale faster than our instrumental resolution (<0.5 ps), and back electron transfer efficiently returns the excited-state population to the ground state on timescales from tens to hundreds of ps. In addition to recent spectroscopic observations of charge transfer state species in DNA by other groups, our results have augmented understanding of the long-lived transient signals observed in DNA strands. The observation of photoinduced electron transfer in these oxidatively damaged nucleobases also supports a recent proposal regarding the role of oxidative products in pre-RNA catalysis. I discuss these observations in the contexts of fundamental DNA excited-state dynamics and prebiotic chemical evolution. In this thesis, I also present the first ultrafast spectroscopic investigation of violacein, a pigment isolated from Antarctic bacteria. Despite claims for the photoprotective role of this pigment, there has never been a spectroscopic analysis of excited-state deactivation in violacein. Emission spectra, fluorescence quantum yields and excited-state lifetimes of violacein in various solvents were measured for the first time. Both the fluorescence quantum yield and excited-state lifetime of violacein increase in increasingly viscous solvents, suggesting a large-scale motion mediates excited-state deactivation. I compare these results to similar observations of viscosity-dependent excited-state decay rates in other molecules. I also consider the relevance of violacein's excited-state properties to the hypothesized sunscreening role of violacein. Overall, the studies presented in this dissertation illustrate how ultrafast spectroscopic techniques can be used to unravel complex biomolecular excited-state dynamics in solution.

Photodynamic activity of pyropheophorbide methyl ester and pyropheophorbide a in dimethylformamide solution.

PubMed

Al-Omari, Saleh; Ali, Ahmad

2009-03-01

Comparative spectroscopic study including the photosensitizers of pyropheophorbide methyl ester (PPME) and pyropheophorbide a (PPa) was performed to study their photodynamic activity. The investigated photosensitizers in a homogeneous system of dimethylformamide (DMF) are not photostable upon irradiation. The photobleaching efficiency of PPa is higher than that of PPME. Combining these results with the data obtained by measuring the singlet oxygen quantum yield and the hydroxyl group generation, it was revealed that the photobleaching efficiency could be correlated with the singlet oxygen quantum yield and the hydroxyl group production of the photosensitizer.

A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics. [titanium alloys

NASA Technical Reports Server (NTRS)

Chen, W.; Dwight, D. W.; Wightman, J. P.

1978-01-01

Various surface preparations for titanium 6-4 alloy were studied. An anodizing method was investigated, and compared with the results of other chemical treatments, namely, phosphate/fluoride, Pasa-Jell and Turco. The relative durability of the different surface treatments was assessed by monitoring changes in surface chemistry and morphology occasioned by aging at 505 K (450 F). Basic electron spectroscopic data were collected for polyimide and polyphenylquinoxaline adhesives and synthetic precursors. Fractographic studies were completed for several combinations of adherend, adhesive, and testing conditions.

Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

NASA Astrophysics Data System (ADS)

Redondo, Pilar; Largo, Antonio; Vega-Vega, Álvaro; Barrientos, Carmen

2015-05-01

The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader's quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN (1Σ) and hydrideisocyanidezinc HZnNC (1Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn]+ composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn+ (2Σ) and HCNZn+ (2Σ).

Linear Response Equilibrium versus echo-planar encoding for fast high-spatial resolution 3D chemical shift imaging

NASA Astrophysics Data System (ADS)

Fischer, Rudolf Fritz; Baltes, Christof; Weiss, Kilian; Pazhenkottil, Aju; Rudin, Markus; Boesiger, Peter; Kozerke, Sebastian

2011-07-01

In this work Linear Response Equilibrium (LRE) and Echo-planar spectroscopic imaging (EPSI) are compared in terms of sensitivity per unit time and power deposition. In addition an extended dual repetition time scheme to generate broad stopbands for improved inherent water suppression in LRE is presented. The feasibility of LRE and EPSI for assessing cholesterol esters in human carotid plaques with high spatial resolution of 1.95 × 1.15 × 1.15 mm 3 on a clinical 3T MR system is demonstrated. In simulations and phantom experiments it is shown that LRE has comparable but lower sensitivity per unit time relative to EPSI despite stronger signal generated. This relates to the lower sampling efficiency in LRE relative to EPSI as a result of limited gradient performance on clinical MR systems. At the same time, power deposition of LRE is significantly reduced compared to EPSI making it an interesting niche application for in vivo high field spectroscopic imaging of metabolites within a limited bandwidth.

Comparison of one-particle basis set extrapolation to explicitly correlated methods for the calculation of accurate quartic force fields, vibrational frequencies, and spectroscopic constants: Application to H2O, N2H+, NO2+, and C2H2

NASA Astrophysics Data System (ADS)

Huang, Xinchuan; Valeev, Edward F.; Lee, Timothy J.

2010-12-01

One-particle basis set extrapolation is compared with one of the new R12 methods for computing highly accurate quartic force fields (QFFs) and spectroscopic data, including molecular structures, rotational constants, and vibrational frequencies for the H2O, N2H+, NO2+, and C2H2 molecules. In general, agreement between the spectroscopic data computed from the best R12 and basis set extrapolation methods is very good with the exception of a few parameters for N2H+ where it is concluded that basis set extrapolation is still preferred. The differences for H2O and NO2+ are small and it is concluded that the QFFs from both approaches are more or less equivalent in accuracy. For C2H2, however, a known one-particle basis set deficiency for C-C multiple bonds significantly degrades the quality of results obtained from basis set extrapolation and in this case the R12 approach is clearly preferred over one-particle basis set extrapolation. The R12 approach used in the present study was modified in order to obtain high precision electronic energies, which are needed when computing a QFF. We also investigated including core-correlation explicitly in the R12 calculations, but conclude that current approaches are lacking. Hence core-correlation is computed as a correction using conventional methods. Considering the results for all four molecules, it is concluded that R12 methods will soon replace basis set extrapolation approaches for high accuracy electronic structure applications such as computing QFFs and spectroscopic data for comparison to high-resolution laboratory or astronomical observations, provided one uses a robust R12 method as we have done here. The specific R12 method used in the present study, CCSD(T)R12, incorporated a reformulation of one intermediate matrix in order to attain machine precision in the electronic energies. Final QFFs for N2H+ and NO2+ were computed, including basis set extrapolation, core-correlation, scalar relativity, and higher-order correlation and then used to compute highly accurate spectroscopic data for all isotopologues. Agreement with high-resolution experiment for 14N2H+ and 14N2D+ was excellent, but for 14N16O2+ agreement for the two stretching fundamentals is outside the expected residual uncertainty in the theoretical values, and it is concluded that there is an error in the experimental quantities. It is hoped that the highly accurate spectroscopic data presented for the minor isotopologues of N2H+ and NO2+ will be useful in the interpretation of future laboratory or astronomical observations.

Accelerated echo-planar J-resolved spectroscopic imaging in the human brain using compressed sensing: a pilot validation in obstructive sleep apnea.

PubMed

Sarma, M K; Nagarajan, R; Macey, P M; Kumar, R; Villablanca, J P; Furuyama, J; Thomas, M A

2014-06-01

Echo-planar J-resolved spectroscopic imaging is a fast spectroscopic technique to record the biochemical information in multiple regions of the brain, but for clinical applications, time is still a constraint. Investigations of neural injury in obstructive sleep apnea have revealed structural changes in the brain, but determining the neurochemical changes requires more detailed measurements across multiple brain regions, demonstrating a need for faster echo-planar J-resolved spectroscopic imaging. Hence, we have extended the compressed sensing reconstruction of prospectively undersampled 4D echo-planar J-resolved spectroscopic imaging to investigate metabolic changes in multiple brain locations of patients with obstructive sleep apnea and healthy controls. Nonuniform undersampling was imposed along 1 spatial and 1 spectral dimension of 4D echo-planar J-resolved spectroscopic imaging, and test-retest reliability of the compressed sensing reconstruction of the nonuniform undersampling data was tested by using a brain phantom. In addition, 9 patients with obstructive sleep apnea and 11 healthy controls were investigated by using a 3T MR imaging/MR spectroscopy scanner. Significantly reduced metabolite differences were observed between patients with obstructive sleep apnea and healthy controls in multiple brain regions: NAA/Cr in the left hippocampus; total Cho/Cr and Glx/Cr in the right hippocampus; total NAA/Cr, taurine/Cr, scyllo-Inositol/Cr, phosphocholine/Cr, and total Cho/Cr in the occipital gray matter; total NAA/Cr and NAA/Cr in the medial frontal white matter; and taurine/Cr and total Cho/Cr in the left frontal white matter regions. The 4D echo-planar J-resolved spectroscopic imaging technique using the nonuniform undersampling-based acquisition and compressed sensing reconstruction in patients with obstructive sleep apnea and healthy brain is feasible in a clinically suitable time. In addition to brain metabolite changes previously reported by 1D MR spectroscopy, our results show changes of additional metabolites in patients with obstructive sleep apnea compared with healthy controls. © 2014 by American Journal of Neuroradiology.

Tomsk Cardiology Center program on lasers in cardiovascular: first results

NASA Astrophysics Data System (ADS)

Gordov, Eugeni P.; Karpov, Rostislav S.; Dudko, Victor A.; Shipulin, Vladimir M.

1994-12-01

Recent progress in biomedical optics resulted in increased activity in this area at a number of different centers. Reported are the first results of the program directed to incorporate at Tomsk Cardiology Center experience gained in Tomsk optical profile research institutions in areas of light-matter interaction, high resolution spectroscopy, laser physics and relevant software and their usage in cardiac therapy, surgery, and diagnostics. To coordinate research work in this direction the special unit-laboratory of laser medicine is organized at the Center. Laboratory activity goes in the following directions: study of spectral properties of vessel walls in norm and atherosclerosis, comparative study of different wavelength laser radiation action on normal and atherosclerotically damaged tissues, novel approach to intravascular imaging, and usage of high sensitive laser spectroscopy for early diagnosis of cardiac diseases. The spectroscopic study of AP and normal tissue is aimed at understanding of differences in internal energy structures and ways of energy migration which are of critical importance for reaching selective laser action on normal and deceased tissues. To compare thermal, mechanical, and photo-chemical variations of tissues caused by laser radiation the XeCl excimer laser with Raman shifting cell and Nd:YAG laser with second, third, and fourth harmonic converters are employed. Fine influence of pulse duration, intensity, and repetition rates on AP removal is considered in laboratory experiments with vessel samples. Preliminary results on theoretical consideration for determination of spectroscopically detectable markers of some cardiac diseases are reported as well.

Proton echo-planar spectroscopic imaging of J-coupled resonances in human brain at 3 and 4 Tesla.

PubMed

Posse, Stefan; Otazo, Ricardo; Caprihan, Arvind; Bustillo, Juan; Chen, Hongji; Henry, Pierre-Gilles; Marjanska, Malgorzata; Gasparovic, Charles; Zuo, Chun; Magnotta, Vincent; Mueller, Bryon; Mullins, Paul; Renshaw, Perry; Ugurbil, Kamil; Lim, Kelvin O; Alger, Jeffry R

2007-08-01

In this multicenter study, 2D spatial mapping of J-coupled resonances at 3T and 4T was performed using short-TE (15 ms) proton echo-planar spectroscopic imaging (PEPSI). Water-suppressed (WS) data were acquired in 8.5 min with 1-cm(3) spatial resolution from a supraventricular axial slice. Optimized outer volume suppression (OVS) enabled mapping in close proximity to peripheral scalp regions. Constrained spectral fitting in reference to a non-WS (NWS) scan was performed with LCModel using correction for relaxation attenuation and partial-volume effects. The concentrations of total choline (tCho), creatine + phosphocreatine (Cr+PCr), glutamate (Glu), glutamate + glutamine (Glu+Gln), myo-inositol (Ins), NAA, NAA+NAAG, and two macromolecular resonances at 0.9 and 2.0 ppm were mapped with mean Cramer-Rao lower bounds (CRLBs) between 6% and 18% and approximately 150-cm(3) sensitive volumes. Aspartate, GABA, glutamine (Gln), glutathione (GSH), phosphoethanolamine (PE), and macromolecules (MMs) at 1.2 ppm were also mapped, although with larger mean CRLBs between 30% and 44%. The CRLBs at 4T were 19% lower on average as compared to 3T, consistent with a higher signal-to-noise ratio (SNR) and increased spectral resolution. Metabolite concentrations were in the ranges reported in previous studies. Glu concentration was significantly higher in gray matter (GM) compared to white matter (WM), as anticipated. The short acquisition time makes this methodology suitable for clinical studies.

Near infrared spectroscopic imaging assessment of cartilage composition: Validation with mid infrared imaging spectroscopy.

PubMed

Palukuru, Uday P; Hanifi, Arash; McGoverin, Cushla M; Devlin, Sean; Lelkes, Peter I; Pleshko, Nancy

2016-07-05

Disease or injury to articular cartilage results in loss of extracellular matrix components which can lead to the development of osteoarthritis (OA). To better understand the process of disease development, there is a need for evaluation of changes in cartilage composition without the requirement of extensive sample preparation. Near infrared (NIR) spectroscopy is a chemical investigative technique based on molecular vibrations that is increasingly used as an assessment tool for studying cartilage composition. However, the assignment of specific molecular vibrations to absorbance bands in the NIR spectrum of cartilage, which arise from overtones and combinations of primary absorbances in the mid infrared (MIR) spectral region, has been challenging. In contrast, MIR spectroscopic assessment of cartilage is well-established, with many studies validating the assignment of specific bands present in MIR spectra to specific molecular vibrations. In the current study, NIR imaging spectroscopic data were obtained for compositional analysis of tissues that served as an in vitro model of OA. MIR spectroscopic data obtained from the identical tissue regions were used as the gold-standard for collagen and proteoglycan (PG) content. MIR spectroscopy in transmittance mode typically requires a much shorter pathlength through the sample (≤10 microns thick) compared to NIR spectroscopy (millimeters). Thus, this study first addressed the linearity of small absorbance bands in the MIR region with increasing tissue thickness, suitable for obtaining a signal in both the MIR and NIR regions. It was found that the linearity of specific, small MIR absorbance bands attributable to the collagen and PG components of cartilage (at 1336 and 856 cm(-1), respectively) are maintained through a thickness of 60 μm, which was also suitable for NIR data collection. MIR and NIR spectral data were then collected from 60 μm thick samples of cartilage degraded with chondroitinase ABC as a model of OA. Partial least squares (PLS) regression using NIR spectra as input predicted the MIR-determined compositional parameters of PG/collagen within 6% of actual values. These results indicate that NIR spectral data can be used to assess molecular changes that occur with cartilage degradation, and further, the data provide a foundation for future clinical studies where NIR fiber optic probes can be used to assess the progression of cartilage degradation. Copyright © 2016 Elsevier B.V. All rights reserved.

A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells.

PubMed

Prima, Eka Cahya; Hidayat, Novianto Nur; Yuliarto, Brian; Suyatman; Dipojono, Hermawan Kresno

2017-01-15

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31+G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31+G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100mW·cm -2 yields a short-circuit current density (J sc ) of 3.23mA/cm 2 , a photovoltage (V oc ) of 0.48V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2μm, the fastest electron transit of 0.22ms, and the longest electron lifetime of 4.29ms. Copyright © 2016 Elsevier B.V. All rights reserved.

A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Prima, Eka Cahya; Hidayat, Novianto Nur; Yuliarto, Brian; Suyatman; Dipojono, Hermawan Kresno

2017-01-01

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31 + G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31 + G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100 mW·cm- 2 yields a short-circuit current density (Jsc) of 3.23 mA/cm2, a photovoltage (Voc) of 0.48 V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2 μm, the fastest electron transit of 0.22 ms, and the longest electron lifetime of 4.29 ms.

Penetration kinetics of dimethyl sulphoxide and glycerol in dynamic optical clearing of porcine skin tissue in vitro studied by Fourier transform infrared spectroscopic imaging.

PubMed

Jiang, Jingying; Boese, Matthias; Turner, Paul; Wang, Ruikang K

2008-01-01

By use of a Fourier transform infrared (FTIR) spectroscopic imaging technique, we examine the dynamic optical clearing processes occurring in hyperosmotically biocompatible agents penetrating into skin tissue in vitro. The sequential collection of images in a time series provides an opportunity to assess penetration kinetics of dimethyl sulphoxide (DMSO) and glycerol beneath the surface of skin tissue over time. From 2-D IR spectroscopic images and 3-D false color diagrams, we show that glycerol takes at least 30 min to finally penetrate the layer of epidermis, while DMSO can be detected in epidermis after only 4 min of being topically applied over stratum corneum sides of porcine skin. The results demonstrate the potential of a FTIR spectroscopic imaging technique as an analytical tool for the study of dynamic optical clearing effects when the bio-tissue is impregnated by hyperosmotically biocompatible agents such as glycerol and DMSO.

First-principles anharmonic quantum calculations for peptide spectroscopy: VSCF calculations and comparison with experiments.

PubMed

Roy, Tapta Kanchan; Sharma, Rahul; Gerber, R Benny

2016-01-21

First-principles quantum calculations for anharmonic vibrational spectroscopy of three protected dipeptides are carried out and compared with experimental data. Using hybrid HF/MP2 potentials, the Vibrational Self-Consistent Field with Second-Order Perturbation Correction (VSCF-PT2) algorithm is used to compute the spectra without any ad hoc scaling or fitting. All of the vibrational modes (135 for the largest system) are treated quantum mechanically and anharmonically using full pair-wise coupling potentials to represent the interaction between different modes. In the hybrid potential scheme the MP2 method is used for the harmonic part of the potential and a modified HF method is used for the anharmonic part. The overall agreement between computed spectra and experiment is very good and reveals different signatures for different conformers. This study shows that first-principles spectroscopic calculations of good accuracy are possible for dipeptides hence it opens possibilities for determination of dipeptide conformer structures by comparison of spectroscopic calculations with experiment.

Development of a new diffuse near-infrared food measuring

NASA Astrophysics Data System (ADS)

Zhang, Jun; Piao, Renguan

2006-11-01

Industries from agriculture to petrochemistry have found near infrared (NIR) spectroscopic analysis useful for quality control and quantitative analysis of materials and products. The general chemical, polymer chemistry, petrochemistry, agriculture, food and textile industries are currently using NIR spectroscopic methods for analysis. In this study, we developed a new sort NIR instrument for food measuring. The instrument consists of a light source, 12 filters to the prismatic part. The special part is that we use a mirror to get two beams of light. And two PbS detectors were used. One detector collected the radiation of one light beam directly and the value was set as the standard instead the standard white surface. Another light beam irradiate the sample surface, and the diffuse light was collected by another detector. The value of the two detectors was compared and the absorbency was computed. We tested the performance of the NIR instrument in determining the protein and fat content of milk powder. The calibration showed the accuracy of the instrument in practice.

Interstellar polycyclic aromatic hydrocarbons - The infrared emission bands, the excitation/emission mechanism, and the astrophysical implications

NASA Technical Reports Server (NTRS)

Allamandola, L. J.; Tielens, G. G. M.; Barker, J. R.

1989-01-01

A comprehensive study of the PAH hypothesis is presented, including the interstellar, IR spectral features which have been attributed to emission from highly vibrationally excited PAHs. Spectroscopic and IR emission features are discussed in detail. A method for calculating the IR fluorescence spectrum from a vibrationally excited molecule is described. Analysis of interstellar spectrum suggests that the PAHs which dominate the IR spectra contain between 20 and 40 C atoms. The results are compared with results from a thermal approximation. It is found that, for high levels of vibrational excitation and emission from low-frequency modes, the two methods produce similar results. Also, consideration is given to the relationship between PAH molecules and amorphous C particles, the most likely interstellar PAH molecular structures, the spectroscopic structure produced by PAHs and PAH-related materials in the UV portion of the interstellar extinction curve, and the influence of PAH charge on the UV, visible, and IR regions.

Spectroscopic investigation of different concentrations of the vapour deposited copper phthalocyanine as a "guest" in polyimide matrix.

PubMed

Georgiev, Anton; Yordanov, Dancho; Dimov, Dean; Assa, Jacob; Spassova, Erinche; Danev, Gencho

2015-04-05

Nanocomposite layers 250 nm copper phthalocyanine/polyimide prepared by simultaneous vapour deposition of three different sources were studied. Different concentrations of copper phthalocyanine as a "guest" in polyimide matrix as a function of conditions of the preparation have been determined by FTIR (Fourier Transform Infrared) and UV-VIS (Ultraviolet-Visible) spectroscopies. The aim was to estimate the possibility of the spectroscopic methods for quantitative determination of the "guest" and compare with the quality of the polyimide thin films in relation to the "guest" concentration. The band at 1334 cm(-1) has been used for quantitative estimation of "guest" in polyimide matrix. The concentrations of the copper phthalocyanine less than 20% require curve fitting techniques with Fourier self deconvolution. The relationship between "guest" concentrations and degree of imidization, as well as the electronic UV-VIS spectra are discussed in relation to the composition, imidization degree and the two crystallographic modification of the embedded chromophore. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluating paper degradation progress. Cross-linking between chromatographic, spectroscopic and chemical results

NASA Astrophysics Data System (ADS)

Łojewski, Tomasz; Zięba, Katarzyna; Knapik, Arkadiusz; Bagniuk, Jacek; Lubańska, Anna; Łojewska, Joanna

2010-09-01

The study presents an overview of the chromatographic (SEC), spectroscopic (FTIR, UV/VIS), viscometric (DP) and chemical methods (titration, pH) used for the evaluation of the degradation progress of various kinds of paper under various conditions. The methods were chosen to follow different routes of paper degradation. Model paper samples represented boundary paper types from pure cellulose cotton paper, through softwood to low quality acidic, sized groundwood paper The accelerated ageing conditions were adjusted to achieve maximum effect (climatic chamber RH 59%, 90oC) and also to mimic the environment inside books (closed vials). The results were settled on the literature data on the degradation mechanisms and compared in terms of the paper types and ageing conditions. The estimators of coupled de-polymerisation and oxidation have been proposed based on the correlation between SEC, UV/VIS and titrative coppper number determination. The overall oxidation index derived from FTIR results was shown to correlate with the summary -CHO and -COOH concentration determined by titrative methods.

PSYCHE CPMG-HSQMBC: An NMR Spectroscopic Method for Precise and Simple Measurement of Long-Range Heteronuclear Coupling Constants.

PubMed

Timári, István; Szilágyi, László; Kövér, Katalin E

2015-09-28

Among the NMR spectroscopic parameters, long-range heteronuclear coupling constants convey invaluable information on torsion angles relevant to glycosidic linkages of carbohydrates. A broadband homonuclear decoupled PSYCHE CPMG-HSQMBC method for the precise and direct measurement of multiple-bond heteronuclear couplings is presented. The PSYCHE scheme built into the pulse sequence efficiently eliminates unwanted proton-proton splittings from the heteronuclear multiplets so that the desired heteronuclear couplings can be determined simply by measuring frequency differences between peak maxima of pure antiphase doublets. Moreover, PSYCHE CPMG-HSQMBC can provide significant improvement in sensitivity as compared to an earlier Zangger-Sterk-based method. Applications of the proposed pulse sequence are demonstrated for the extraction of (n)J((1)H,(77)Se) and (n)J((1)H,(13)C) values, respectively, in carbohydrates; further extensions can be envisioned in any J-based structural and conformational studies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A spectroscopic comparison of selected Chinese kaolinite, coal bearing kaolinite and halloysite--a mid-infrared and near-infrared study.

PubMed

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

2010-11-01

Mid-infrared (MIR) and near-infrared (NIR) spectroscopy have been compared and evaluated for differentiating kaolinite, coal bearing kaolinite and halloysite. Kaolinite, coal bearing kaolinite and halloysite are the three relative abundant minerals of the kaolin group, especially in China. In the MIR spectra, the differences are shown in the 3000-3600 cm⁻¹ between kaolinite and halloysite. It cannot obviously differentiate the kaolinite and halloysite, leaving alone kaolinite and coal bearing kaolinite. However, NIR, together with MIR, gives us the sufficient evidence to differentiate the kaolinite and halloysite, especially kaolinite and coal bearing kaolinite. There are obvious differences between kaolinite and halloysite in all range of their spectra, and they also show some difference between kaolinite and coal bearing kaolinite. Therefore, the reproducibility of measurement, signal to noise ratio and richness of qualitative information should be simultaneously considered for proper selection of a spectroscopic method for mineral analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Allamandola, L. J.

1989-01-01

The spectroscopic analysis of pristine cometary material provides a very important probe of the chemical identity of the material as well as of the physical and chemical conditions which prevailed during the comet's history. Concerning classical spectroscopy, the spectral regions which will most likely prove most useful are the infrared, the visible and ultraviolet. Newer spectroscopic techniques which have the potential to provide equally important information include nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Each technique is summarized with emphasis placed on the kind of information which can be obtained.

An AzTEC 1.1mm survey of the GOODS-N field - II. Multiwavelength identifications and redshift distribution

NASA Astrophysics Data System (ADS)

Chapin, Edward L.; Pope, Alexandra; Scott, Douglas; Aretxaga, Itziar; Austermann, Jason E.; Chary, Ranga-Ram; Coppin, Kristen; Halpern, Mark; Hughes, David H.; Lowenthal, James D.; Morrison, Glenn E.; Perera, Thushara A.; Scott, Kimberly S.; Wilson, Grant W.; Yun, Min S.

2009-10-01

We present results from a multiwavelength study of 29 sources (false detection probabilities <5 per cent) from a survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field at 1.1mm using the Astronomical Thermal Emission Camera (AzTEC). Comparing with existing 850μm Submillimetre Common-User Bolometer Array (SCUBA) studies in the field, we examine differences in the source populations selected at the two wavelengths. The AzTEC observations uniformly cover the entire survey field to a 1σ depth of ~1mJy. Searching deep 1.4GHz Very Large Array (VLA) and Spitzer 3-24μm catalogues, we identify robust counterparts for 21 1.1mm sources, and tentative associations for the remaining objects. The redshift distribution of AzTEC sources is inferred from available spectroscopic and photometric redshifts. We find a median redshift of z = 2.7, somewhat higher than z = 2.0 for 850μm selected sources in the same field, and our lowest redshift identification lies at a spectroscopic redshift z = 1.1460. We measure the 850μm to 1.1mm colour of our sources and do not find evidence for `850μm dropouts', which can be explained by the low signal-to-noise ratio of the observations. We also combine these observed colours with spectroscopic redshifts to derive the range of dust temperatures T, and dust emissivity indices β for the sample, concluding that existing estimates T ~ 30K and β ~ 1.75 are consistent with these new data.

Mid-Infrared Spectroscopy of Polycyclic Aromatic Nitrogen Heterocycles (PANHS) and their Ions

NASA Technical Reports Server (NTRS)

Mattioda, Andrew L.; Hudgin, Douglas; Bauschlicher, Charles W.; Alamandola, Louis J.

2003-01-01

In recent years, polycyclic aromatic nitrogen heterocycles (PANHs) have attracted a good deal of attention because of their potent carcinogenic and mutagenic properties, and their prevalence in our environment. Such species also play a prominent role in the chemistry of life up to and including the very nucleobases from which our DNA is constructed. Surprisingly, these compounds may even be common outside of our terrestrial environment. To wit, it is now widely accepted that polycyclic aromatic materials are abundant in space and represent a major reservoir of organic carbon in the interstellar medium and developing planetary systems. Given that nitrogen is the fourth most abundant chemically reactive element in space (surpassed only by hydrogen, carbon, and oxygen), it is entirely reasonable to suspect that PANHs may represent an important component of that organic reservoir. Motivated by their intrinsic merit and with special attention toward evaluating their exobiological significance, we have initiated a program to study the spectroscopic and chemical properties of P A " s under conditions relevant to extraterrestrial environments. Here we present the first results of that program-infrared spectroscopic measurements on a series of PANH"s in neutral and cationic forms, isolated in inert matrices at cryogenic temperatures.temperatures. The species studied include: 1 -, and 2-azabenz[a]anthracene, 1-, 2-, and 4- azachrysene, dibenz[a,h]acridine, and dibenz[a,J)acridine. The experimental measurements are also compared with theoretical spectra calculated using density functional theory. General spectroscopic trends observed in this series of compounds are discussed and the implications of these results for Astrophysics and Exobiology are considered.

IR spectroscopic studies in microchannel structures

NASA Astrophysics Data System (ADS)

Guber, A. E.; Bier, W.

1998-06-01

By means of the various microengineering methods available, microreaction systems can be produced among others. These microreactors consist of microchannels, where chemical reactions take place under defined conditions. For optimum process control, continuous online analytics is envisaged in the microchannels. For this purpose, a special analytical module has been developed. It may be applied for IR spectroscopic studies at any point of the microchannel.

A Spectroscopic study on the fuel value of softwoods in relation to chemical composition

Treesearch

Chi-Leung So; Thomas L. Eberhardt; Les Groom; Todd F. Shupe

2012-01-01

The recent focus on bioenergy has led to interest in developing alternative technologies for assessing the fuel value of available biomass resources. In this study, both near- and mid-infrared spectroscopic datawere used to predict fuel value in relation to extractives and lignin contents for longleaf pine wood. Samples were analyzed both before and after extraction....

Super-Diffraction Limited Measurements through the Turbulent Atmosphere by Speckle Interferometry

DTIC Science & Technology

1990-02-22

independently confirmed by a submotion in the residuals to spectroscopically obtained radial velocities of the system. / (3) Atmospheric Turbulence Studies ...spectroscopically obtained radial velocities 1. (3) Atmospheric Turbulence Studies - The very extensive data accumu- lated under this project at the two... studies . I B. RESEARCH ACCOMPLISHMENTS 1. Observing Opportunities Observing time on the 1.8-meter telescope was provided by the Lowell Observatory3 on a

DFT calculations for anharmonic force field and spectroscopic constants of YC2 and its 13C isotopologues

NASA Astrophysics Data System (ADS)

Zhao, Yanliang; Wang, Meishan; Yang, Chuanlu; Ma, Xiaoguang; Li, Jing

2018-02-01

The construction of the complete third and the semi-diagonal quartic force fields including the anharmonicity of the ground state (X˜2A1) for yttrium dicarbide (YC2) is carried out employing the vibrational second-order perturbation theory (VPT2) in combination with the density functional theory (DFT). The equilibrium geometries optimization, anharmonic force field and vibrational spectroscopic constants of YC2 are calculated by B3LYP, B3PW91 and B3P86 methods. Aug-cc-pVnZ (n = D, T, Q) and cc-pVnZ-PP (n = D, T, Q) basis sets are chosen for C and Y atoms, respectively. The calculated geometry parameters of YC2 agree well with the corresponding experimental and previous theoretical results. The bonding characters of Ysbnd C2 or Csbnd C are discussed. Based on the optimized equilibrium geometries, the spectroscopic constants and anharmonic force field of YC2 are calculated. Comparing with the spectroscopic constants of YC2 derived from the experiment, the calculated results show that the B3PW91 and B3P86 methods are superior to B3LYP for YC2. The Coriolis coupling constants, cubic and quartic force constants of YC2 are reasonably predicted. Besides, the spectroscopic constants and anharmonic force field of Y13C2 (X˜2A1) and Y13CC (X˜2A‧) are calculated for the first time, which are expected to guide the high resolution experimental work for YC2 and its 13C isotopologues.

Comparing paraffined and deparaffinized breast cancer tissue samples and an analysis of Raman spectroscopy and infrared methods

NASA Astrophysics Data System (ADS)

Depciuch, J.; Kaznowska, E.; Szmuc, K.; Zawlik, I.; Cholewa, M.; Heraud, P.; Cebulski, J.

2016-05-01

Breast cancer makes up a quarter of all cancer in women, which is why research into new diagnostic methods and sample preparations need to be developed at an accelerated pace. Researchers are looking for diagnostic tools to detect when an individual has cancer cells and use that information to see what measurements and approaches can be used to take further diagnostic steps. The most common method of sample preparation is the imbibing of tumor tissue in paraffin, which can produce a background for spectroscopic measurements in the range of 500-3500 cm-1. In this study we demonstrated that proper preparation of paraffin-embedded specimens and the measurement methodology can eliminate paraffin vibration, as was done in the work Depciuch et al. 2015. Thanks to this spectroscopic technique there may become a reliable and accurate method of diagnosing breast cancer based on the evidence found from the prepared samples. The study compared the results obtained through Raman spectroscopy and FTIR (Fourier Transform Infrared) measurements of healthy and cancerous breast tissues that were either embedded in paraffin or deparaffinized. The resulting spectrum and accurate analysis led to the conclusion that the appropriate measurement of the background and the elimination of peaks from the paraffin had the greatest impact on the reliability of results. Furthermore, after the accurate, detailed studies FTIR and Raman spectroscopy on samples of breast tissue that were deparaffinized or embedded in paraffin, including a complete analysis of the peak after transformation Kramers-Kröning (KK), it was found that sample preparation did not affect the result obtained by measuring the reflectance in the mid-infrared range, and that this only had a minimal effect relating to the intensity obtained by the measurement of the Raman peak. Only in special cases, when Raman spectroscopic methods are used for research to find the peculiarities of the spectra, are deparaffinization recommended, in order to attain more detailed results that could be crucial in understanding the process of carcinogenesis.

Spectroscopic factors in the N =20 island of inversion: The Nilsson strong-coupling limit

NASA Astrophysics Data System (ADS)

Macchiavelli, A. O.; Crawford, H. L.; Campbell, C. M.; Clark, R. M.; Cromaz, M.; Fallon, P.; Jones, M. D.; Lee, I. Y.; Richard, A. L.; Salathe, M.

2017-11-01

Spectroscopic factors, extracted from one-neutron knockout and Coulomb dissociation reactions, for transitions from the ground state of 33Mg to the ground-state rotational band in 32Mg, and from 32Mg to low-lying negative-parity states in 31Mg, are interpreted within the rotational model. Associating the ground state of 33Mg and the negative-parity states in 31Mg with the 3/2 [321 ] Nilsson level, the strong coupling limit gives simple expressions that relate the amplitudes (Cj ℓ) of this wave function with the measured cross sections and derived spectroscopic factors (Sj ℓ). To obtain a consistent agreement with the data within this framework, we find that one requires a modified 3/2 [321 ] wave function with an increased contribution from the spherical 2 p3 /2 orbit as compared to a standard Nilsson calculation. This is consistent with the findings of large-scale shell model calculations and can be traced to weak binding effects that lower the energy of low-ℓ orbitals.

Spectroscopic comparison of effects of electron radiation on mechanical properties of two polyimides

NASA Technical Reports Server (NTRS)

Long, Edward R., Jr.; Long, Sheila Ann T.

1987-01-01

The differences in the radiation durabilities of two polyimide materials, Du Pont Kapton and General Electric Ultem, are compared. An explanation of the basic mechanisms which occur during exposure to electron radiation from analyses of infrared (IR) and electron paramagnetic resonance (EPR) spectroscopic data for each material is provided. The molecular model for Kapton was, in part, established from earlier modeling for Ultem (pp. 1293-1298 of IEEE Transactions on Nuclear Science, December 1984). Techniques for understanding the durability of one complex polymer based on the understanding of a different and equally complex polymer are demonstrated. The spectroscopic data showed that the primary radiation-generated change in the tensile properties of Ultem (a large reduction in tensile elongation) was due to crosslinking, which followed the capture by phenyl radicals of hydrogen atoms removed from gem-dimethyl groups. In contrast, the tensile properties of Kapton remained unchanged because radical-radical recombination, a self-mending process, took place.

Resolution and Orbit Reconstruction of Spectroscopic Binary Stars with the Palomar Testbed Interferometer

NASA Astrophysics Data System (ADS)

Boden, A. F.; Lane, B. F.; Creech-Eakman, M. J.; Queloz, D.; Koresko, C. D.

2000-05-01

The Palomar Testbed Interferometer (PTI) is a long-baseline near-infrared interferometer located at Palomar Observatory. For the past several years we have had an ongoing program of resolving and reconstructing the visual and physical orbits of spectroscopic binary stars with PTI, with the goal of obtaining precise dynamical mass estimates and other physical parameters. We will present a number of new visual and physical orbit determinations derived from integrated reductions of PTI visibility and archival and new spectroscopic radial velocity data. The systems for which we will discuss our orbit models are: iota Pegasi (HD 210027), 64 Psc (HD 4676), 12 Boo (HD 123999), 75 Cnc (HD 78418), 47 And (HD 8374), HD 205539, BY Draconis (HDE 234677), and 3 Boo (HD 120064), and 3 Boo (HD 120064). All of these systems are double-lined binary systems (SB2), and integrated astrometric/radial velocity orbit modeling provides precise fundamental parameters (mass, luminosity) and system distance determinations comparable with Hipparcos precisions.

Multiband Photometric and Spectroscopic Analysis of HV Cnc

NASA Astrophysics Data System (ADS)

Gökay, G.; Gürol, B.; Derman, E.

2013-11-01

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.

MULTIBAND PHOTOMETRIC AND SPECTROSCOPIC ANALYSIS OF HV Cnc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gökay, G.; Gürol, B.; Derman, E., E-mail: ggokay@science.ankara.edu.tr

2013-11-01

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

Detection of spectroscopic binaries: lessons from the Gaia-ESO survey

NASA Astrophysics Data System (ADS)

van der Swaelmen, Mathieu; Merle, Thibault; van Eck, Sophie; Jorissen, Alain; Zwitter, Tomaž

2018-04-01

The Gaia-ESO survey (GES; Gilmore et al. (2012), Randich et al. (2013)) is a spectroscopic survey complementing the Gaia mission to bring accurate radial velocities and chemical abundances for 105 stars. Merle et al. (submitted to A&A see also this volume) developped a tool (DOE) to detect multiple peaks in the cross-correlation functions (CCFs) of GES spectra. Using the GIRAFFE HR10 and HR21 settings, we were able to compare the efficiency of our SB detection tool depending on the wavelength range and resolution. We show that a careful design of CCF masks can improve the detection rate in the HR21 settings. HR21 spectra are similar to the ones produced by the RVS spectrograph of the Gaia mission, though the lower resolution of RVS spectra may result in a lower detection efficiency than the case of HR21. Analysis of RVS spectra in the context of spectroscopic binaries can take advantage of the lessons learnt from the GES to maximize the detection rate.

Fully nonlocal inelastic scattering computations for spectroscopical transmission electron microscopy methods

NASA Astrophysics Data System (ADS)

Rusz, Ján; Lubk, Axel; Spiegelberg, Jakob; Tyutyunnikov, Dmitry

2017-12-01

The complex interplay of elastic and inelastic scattering amenable to different levels of approximation constitutes the major challenge for the computation and hence interpretation of TEM-based spectroscopical methods. The two major approaches to calculate inelastic scattering cross sections of fast electrons on crystals—Yoshioka-equations-based forward propagation and the reciprocal wave method—are founded in two conceptually differing schemes—a numerical forward integration of each inelastically scattered wave function, yielding the exit density matrix, and a computation of inelastic scattering matrix elements using elastically scattered initial and final states (double channeling). Here, we compare both approaches and show that the latter is computationally competitive to the former by exploiting analytical integration schemes over multiple excited states. Moreover, we show how to include full nonlocality of the inelastic scattering event, neglected in the forward propagation approaches, at no additional computing costs in the reciprocal wave method. Detailed simulations show in some cases significant errors due to the z -locality approximation and hence pitfalls in the interpretation of spectroscopical TEM results.

Systematic shell-model study on spectroscopic properties from light to heavy nuclei

NASA Astrophysics Data System (ADS)

Yuan, Cenxi

2018-05-01

A systematic shell-model study is performed to study the spectroscopic properties from light to heavy nuclei, such as binding energies, energy levels, electromagnetic properties, and β decays. The importance of cross-shell excitation is shown in the spectroscopic properties of neutron-rich boron, carbon, nitrogen, and oxygen isotopes. A special case is presented for low-lying structure of 14C. The weakly bound effect of proton 1s1/2 orbit is necessary for the description of the mirror energy difference in the nuclei around A=20. Some possible isomers are predicted in the nuclei in the southeast region of 132Sn based on a newly suggested Hamiltonian. A preliminary study on the nuclei around 208Pb are given to show the ability of the shell model in the heavy nuclei.

Spectroscopic study of gel grown L-Valine Zinc Glycine Thiourea Sulfate (VZGTS) crystal: A novel NLO crystal

NASA Astrophysics Data System (ADS)

Rathod, Kiran T.; Patel, I. B.

2017-05-01

In recent years, organometalic non linear optical (NLO) materials have attained immense appeal form researchers due to its range of technological applications in photonic field and optoelectronic technology. In present research work, novel semi organic NLO L-Valine Zinc Glycine Thiourea Sulfate crystals (VZGTS) with different morphologies were grown by gel method at ambient temperature. Presence and identification of functional groups were confirmed by FITR analysis. Spectroscopic studies were carried out for it. The UV-Vis spectroscopy is recorded for crystal. PL study stats that the crystal has insulating nature. Spectroscopic study shows that this crystal has good transparency in the case of fundamental wavelength of Nd : YAG laser. Second Harmonic Generation (SHG) efficiency was confirmed by Kurtz - Perry powder method. Results are discussed in the paper.

SPIDERS: the spectroscopic follow-up of X-ray selected clusters of galaxies in SDSS-IV

NASA Astrophysics Data System (ADS)

Clerc, N.; Merloni, A.; Zhang, Y.-Y.; Finoguenov, A.; Dwelly, T.; Nandra, K.; Collins, C.; Dawson, K.; Kneib, J.-P.; Rozo, E.; Rykoff, E.; Sadibekova, T.; Brownstein, J.; Lin, Y.-T.; Ridl, J.; Salvato, M.; Schwope, A.; Steinmetz, M.; Seo, H.-J.; Tinker, J.

2016-12-01

SPIDERS (The SPectroscopic IDentification of eROSITA Sources) is a programme dedicated to the homogeneous and complete spectroscopic follow-up of X-ray active galactic nuclei and galaxy clusters over a large area (˜7500 deg2) of the extragalactic sky. SPIDERS is part of the Sloan Digital Sky Survey (SDSS)-IV project, together with the Extended Baryon Oscillation Spectroscopic Survey and the Time-Domain Spectroscopic Survey. This paper describes the largest project within SPIDERS before the launch of eROSITA: an optical spectroscopic survey of X-ray-selected, massive (˜1014-1015 M⊙) galaxy clusters discovered in ROSAT and XMM-Newton imaging. The immediate aim is to determine precise (Δz ˜ 0.001) redshifts for 4000-5000 of these systems out to z ˜ 0.6. The scientific goal of the program is precision cosmology, using clusters as probes of large-scale structure in the expanding Universe. We present the cluster samples, target selection algorithms and observation strategies. We demonstrate the efficiency of selecting targets using a combination of SDSS imaging data, a robust red-sequence finder and a dedicated prioritization scheme. We describe a set of algorithms and work-flow developed to collate spectra and assign cluster membership, and to deliver catalogues of spectroscopically confirmed clusters. We discuss the relevance of line-of-sight velocity dispersion estimators for the richer systems. We illustrate our techniques by constructing a catalogue of 230 spectroscopically validated clusters (0.031 < z < 0.658), found in pilot observations. We discuss two potential science applications of the SPIDERS sample: the study of the X-ray luminosity-velocity dispersion (LX-σ) relation and the building of stacked phase-space diagrams.

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...

Prediction and interpretation of infrared intensities of polymethylene chain molecules

NASA Astrophysics Data System (ADS)

Jona, P.; Gussoni, M.; Zerbi, G.

1986-03-01

We have calculated the IR intensities of some polymethylene chain molecules containing conformational defects or polar heads. Calculations provide spectroscopic markers of end-TG, GTG', GTG, GG and GGTGG defects. Further, a spectroscopical study of interactions between polar heads and alkyl chain is allowed.

An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: Spectroscopic Redshifts

NASA Astrophysics Data System (ADS)

Danielson, A. L. R.; Swinbank, A. M.; Smail, Ian; Simpson, J. M.; Casey, C. M.; Chapman, S. C.; da Cunha, E.; Hodge, J. A.; Walter, F.; Wardlow, J. L.; Alexander, D. M.; Brandt, W. N.; de Breuck, C.; Coppin, K. E. K.; Dannerbauer, H.; Dickinson, M.; Edge, A. C.; Gawiser, E.; Ivison, R. J.; Karim, A.; Kovacs, A.; Lutz, D.; Menten, K.; Schinnerer, E.; Weiß, A.; van der Werf, P.

2017-05-01

We present spectroscopic redshifts of {\\text{}}{S}870μ {{m}} ≳ 2 mJy submillimeter galaxies (SMGs), which have been identified from the ALMA follow-up observations of 870 μm detected sources in the Extended Chandra Deep Field South (the ALMA-LESS survey). We derive spectroscopic redshifts for 52 SMGs, with a median of z = 2.4 ± 0.1. However, the distribution features a high-redshift tail, with ˜23% of the SMGs at z≥slant 3. Spectral diagnostics suggest that the SMGs are young starbursts, and the velocity offsets between the nebular emission and UV ISM absorption lines suggest that many are driving winds, with velocity offsets of up to 2000 km s-1. Using the spectroscopic redshifts and the extensive UV-to-radio photometry in this field, we produce optimized spectral energy distributions (SEDs) using Magphys, and use the SEDs to infer a median stellar mass of {M}\\star = (6 ± 1)× 1010 M {}⊙ for our SMGs with spectroscopic redshift. By combining these stellar masses with the star formation rates (measured from the far-infrared SEDs), we show that SMGs (on average) lie a factor of ˜5 above the so-called “main sequence” at z˜ 2. We provide this library of 52 template fits with robust and uniquely well-sampled SEDs as a resource for future studies of SMGs, and also release the spectroscopic catalog of ˜2000 (mostly infrared-selected) galaxies targeted as part of the spectroscopic campaign.

Spectroscopy by joint spectral and time domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Szkulmowski, Maciej; Tamborski, Szymon; Wojtkowski, Maciej

2015-03-01

We present the methodology for spectroscopic examination of absorbing media being the combination of Spectral Optical Coherence Tomography and Fourier Transform Spectroscopy. The method bases on the joint Spectral and Time OCT computational scheme and simplifies data analysis procedure as compared to the mostly used windowing-based Spectroscopic OCT methods. The proposed experimental setup is self-calibrating in terms of wavelength-pixel assignment. The performance of the method in measuring absorption spectrum was checked with the use of the reflecting phantom filled with the absorbing agent (indocyanine green). The results show quantitative accordance with the controlled exact results provided by the reference method.

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

NASA Technical Reports Server (NTRS)

Walker, A. B. C., Jr.

1975-01-01

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

Pharmaceutical properties of two ethenzamide-gentisic acid cocrystal polymorphs: Drug release profiles, spectroscopic studies and theoretical calculations.

PubMed

Sokal, Agnieszka; Pindelska, Edyta; Szeleszczuk, Lukasz; Kolodziejski, Waclaw

2017-04-30

The aim of this study was to evaluate the stability and solubility of the polymorphic forms of the ethenzamide (ET) - gentisic acid (GA) cocrystals during standard technological processes leading to tablet formation, such as compression and excipient addition. In this work two polymorphic forms of pharmaceutical cocrystals (ETGA) were characterized by 13 C and 15 N solid-state nuclear magnetic resonance and Fourier transformed infrared spectroscopy. Spectroscopic studies were supported by gauge including projector augmented wave (GIPAW) calculations of chemical shielding constants.Polymorphs of cocrystals were easily identified and characterized on the basis of solid-state spectroscopic studies. ETGA cocrystals behaviour during direct compressionand tabletting with excipient addition were tested. In order to choose the best tablet composition with suitable properties for the pharmaceutical industry dissolution profile studies of tablets containing polymorphic forms of cocrystals with selected excipients were carried out. Copyright © 2017. Published by Elsevier B.V.

The Time-domain Spectroscopic Survey: Target Selection for Repeat Spectroscopy

NASA Astrophysics Data System (ADS)

MacLeod, Chelsea L.; Green, Paul J.; Anderson, Scott F.; Eracleous, Michael; Ruan, John J.; Runnoe, Jessie; Nielsen Brandt, William; Badenes, Carles; Greene, Jenny; Morganson, Eric; Schmidt, Sarah J.; Schwope, Axel; Shen, Yue; Amaro, Rachael; Lebleu, Amy; Filiz Ak, Nurten; Grier, Catherine J.; Hoover, Daniel; McGraw, Sean M.; Dawson, Kyle; Hall, Patrick B.; Hawley, Suzanne L.; Mariappan, Vivek; Myers, Adam D.; Pâris, Isabelle; Schneider, Donald P.; Stassun, Keivan G.; Bershady, Matthew A.; Blanton, Michael R.; Seo, Hee-Jong; Tinker, Jeremy; Fernández-Trincado, J. G.; Chambers, Kenneth; Kaiser, Nick; Kudritzki, R.-P.; Magnier, Eugene; Metcalfe, Nigel; Waters, Chris Z.

2018-01-01

As astronomers increasingly exploit the information available in the time domain, spectroscopic variability in particular opens broad new channels of investigation. Here we describe the selection algorithms for all targets intended for repeat spectroscopy in the Time Domain Spectroscopic Survey (TDSS), part of the extended Baryon Oscillation Spectroscopic Survey within the Sloan Digital Sky Survey (SDSS)-IV. Also discussed are the scientific rationale and technical constraints leading to these target selections. The TDSS includes a large “repeat quasar spectroscopy” (RQS) program delivering ∼13,000 repeat spectra of confirmed SDSS quasars, and several smaller “few-epoch spectroscopy” (FES) programs targeting specific classes of quasars as well as stars. The RQS program aims to provide a large and diverse quasar data set for studying variations in quasar spectra on timescales of years, a comparison sample for the FES quasar programs, and an opportunity for discovering rare, serendipitous events. The FES programs cover a wide variety of phenomena in both quasars and stars. Quasar FES programs target broad absorption line quasars, high signal-to-noise ratio normal broad line quasars, quasars with double-peaked or very asymmetric broad emission line profiles, binary supermassive black hole candidates, and the most photometrically variable quasars. Strongly variable stars are also targeted for repeat spectroscopy, encompassing many types of eclipsing binary systems, and classical pulsators like RR Lyrae. Other stellar FES programs allow spectroscopic variability studies of active ultracool dwarf stars, dwarf carbon stars, and white dwarf/M dwarf spectroscopic binaries. We present example TDSS spectra and describe anticipated sample sizes and results.

Semi-synthesis of dihydrochalcone derivatives and their in vitro antimicrobial activities.

PubMed

Awouafack, Maurice D; Kusari, Souvik; Lamshöft, Marc; Ngamga, Dieudonne; Tane, Pierre; Spiteller, Michael

2010-04-01

We describe the semi-synthesis of dihydrochalcone derivatives and their IN VITRO antimicrobial activities. These compounds were prepared by modifying two naturally occurring antimicrobial dihydrochalcones, erioschalcones A and B, reported by us earlier. The structures of the compounds were assigned on the basis of spectroscopic evidence and by comparing their physical and spectroscopic data with those reported in the literature. All the compounds were subjected to IN VITRO antimicrobial assays against a panel of pathogenic microorganisms, including gram-positive and gram-negative bacteria, and fungi. The antimicrobial efficacies of this class of compounds were established by correlating the activity profile of each compound with its structure and by comparing the activities of all the compounds with each other based on their structure. This should enable the development of other derivatives of the dihydrochalcone family that would serve as more potent antimicrobial agents against specific pathogens. Georg Thieme Verlag KG Stuttgart.New York.

Widely tunable (PbSn)Te lasers using etched cavities for mass production. [for infrared spectroscopic applications

NASA Technical Reports Server (NTRS)

Miller, M. D.

1980-01-01

Lead salt diode lasers are being used increasingly as tunable sources of monochromatic infrared radiation in a variety of spectroscopic systems. These devices are particularly useful, both in the laboratory and in the field, because of their high spectral brightness (compared to thermal sources) and wide spectral coverage (compared to line-tunable gas lasers). While the primary commercial application of these lasers has been for ultrahigh resolution laboratory spectroscopy, there are numerous systems applications, including laser absorbtion pollution monitors and laser heterodyne radiometers, for which diode lasers have great potential utility. Problem areas related to the wider use of these components are identified. Among these are total tuning range, mode control, and high fabrication cost. A fabrication technique which specifically addresses the problems of tuning range and cost, and which also has potential application for mode control, is reported.

Structural characterization, spectroscopic signatures, nonlinear optical response, and antioxidant property of 4-benzyloxybenzaldehyde and its binding activity with microtubule-associated tau protein

NASA Astrophysics Data System (ADS)

Anbu, V.; Vijayalakshmi, K. A.; Karthick, T.; Tandon, Poonam; Narayana, B.

2017-09-01

In the proposed work, the non-linear optical response, spectroscopic signature and binding activity of 4-Benzyloxybenzaldehyde (4BB) has been investigated. In order to find the vibrational contribution of functional groups in mixed or coupled modes in the experimental FT-IR and FT-Raman spectra, the potential energy distribution (PED) based on the internal coordinates have been computed. Since the molecule exists in the form of dimer in solid state, the electronic structure of dimer has been proposed in order to explain the intermolecular hydrogen bonding interactions via aldehyde group. The experimental and simulated powder X-ray diffraction data was compared and the miller indices which define the crystallographic planes in the crystal lattices were identified. Optical transmittance and absorbance measurement were taken at ambient temperature in order to investigate the transparency and optical band gap. For screening the material for nonlinear applications, theoretical second order hyperpolarizability studies were performed and compared with the standard reference urea. To validate the theoretical results, powder second harmonic generation (SHG) studies were carried out using Kurtz and Perry technique. The results show that the molecule studied in this work exhibit considerable non-linear optical (NLO) response. In addition to the characterization and NLO studies, we also claimed based on the experimental and theoretical data that the molecule shows antioxidant property and inhibition capability. Since the title molecule shows significant binding with Tau protein that helps to stabilize microtubules in the nervous system, the molecular docking investigation was performed to find the inhibition constant, binding affinity and active binding residues.

Extended X-ray Absorption Fine Structure Study of Bond Constraints in Ge-Sb-Te Alloys

DTIC Science & Technology

2011-02-07

Ray Absorption Spectroscopy, or EXAFS. Using the spectroscopic capabilities provided by the MCAT line at the Advanced Photon Source at Argonne...Absorption Spectroscopy, or EXAFS. Using the spectroscopic capabilities provided by the MCAT line at the Advanced Photon Source at Argonne National

Analysis of Counterfeit Coated Tablets and Multi-Layer Packaging Materials Using Infrared Microspectroscopic Imaging.

PubMed

Winner, Taryn L; Lanzarotta, Adam; Sommer, André J

2016-06-01

An effective method for detecting and characterizing counterfeit finished dosage forms and packaging materials is described in this study. Using attenuated total internal reflection Fourier transform infrared spectroscopic imaging, suspect tablet coating and core formulations as well as multi-layered foil safety seals, bottle labels, and cigarette tear tapes were analyzed and compared directly with those of a stored authentic product. The approach was effective for obtaining molecular information from structures as small as 6 μm.

Principles of ESCA and application to metal corrosion, coating and lubrication

NASA Technical Reports Server (NTRS)

Wheeler, D. R.

1978-01-01

The principles of ESCA (electron spectroscopy for chemical analysis) were described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques were evaluated. The use of ESCA was illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. A bibliography of material that was useful for further study of ESCA was presented and commented upon.

Raman Spectroscopic Imaging of the Whole Ciona intestinalis Embryo during Development

PubMed Central

Nakamura, Mitsuru J.; Hotta, Kohji; Oka, Kotaro

2013-01-01

Intracellular composition and the distribution of bio-molecules play central roles in the specification of cell fates and morphogenesis during embryogenesis. Consequently, investigation of changes in the expression and distribution of bio-molecules, especially mRNAs and proteins, is an important challenge in developmental biology. Raman spectroscopic imaging, a non-invasive and label-free technique, allows simultaneous imaging of the intracellular composition and distribution of multiple bio-molecules. In this study, we explored the application of Raman spectroscopic imaging in the whole Ciona intestinalis embryo during development. Analysis of Raman spectra scattered from C. intestinalis embryos revealed a number of localized patterns of high Raman intensity within the embryo. Based on the observed distribution of bio-molecules, we succeeded in identifying the location and structure of differentiated muscle and endoderm within the whole embryo, up to the tailbud stage, in a label-free manner. Furthermore, during cell differentiation, we detected significant differences in cell state between muscle/endoderm daughter cells and daughter cells with other fates that had divided from the same mother cells; this was achieved by focusing on the Raman intensity of single Raman bands at 1002 or 1526 cm−1, respectively. This study reports the first application of Raman spectroscopic imaging to the study of identifying and characterizing differentiating tissues in a whole chordate embryo. Our results suggest that Raman spectroscopic imaging is a feasible label-free technique for investigating the developmental process of the whole embryo of C. intestinalis. PMID:23977129

Revisiting Abell 2744: a powerful synergy of GLASS spectroscopy and HFF photometry

NASA Astrophysics Data System (ADS)

Wang, Xin; Wang

We present new emission line identifications and improve the lensing reconstruction of the mass distribution of galaxy cluster Abell 2744 using the Grism Lens-Amplified Survey from Space (GLASS) spectroscopy and the Hubble Frontier Fields (HFF) imaging. We performed blind and targeted searches for faint line emitters on all objects, including the arc sample, within the field of view (FoV) of GLASS prime pointings. We report 55 high quality spectroscopic redshifts, 5 of which are for arc images. We also present an extensive analysis based on the HFF photometry, measuring the colors and photometric redshifts of all objects within the FoV, and comparing the spectroscopic and photometric redshift estimates. In order to improve the lens model of Abell 2744, we develop a rigorous algorithm to screen arc images, based on their colors and morphology, and selecting the most reliable ones to use. As a result, 25 systems (corresponding to 72 images) pass the screening process and are used to reconstruct the gravitational potential of the cluster pixellated on an adaptive mesh. The resulting total mass distribution is compared with a stellar mass map obtained from the Spitzer Frontier Fields data in order to study the relative distribution of stars and dark matter in the cluster.

Assessment of different excitation wavelengths for photodetecting neoplastic urothelial lesions by laser-induced autofluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Anidjar, Maurice; Cussenot, Oliver; Avrillier, Sigrid; Ettori, Dominique; Teillac, Pierre; Le Duc, Alain

1996-04-01

We have designed a program using laser induced autofluorescence spectroscopy as a possible way to characterize urothelial tumors of the bladder. The autofluorescence spectra were compared between normal, suspicious and tumor areas of human bladder. Three different pulsed laser wavelengths were used for excitation: 308 nm (excimer), 337 nm (nitrogen) and 480 nm (dye laser). Excitation light was delivered by a specially devised multifiber catheter introduced through the working channel of a regular cystoscope under saline irrigation. The fluorescence light was focused into an optical multichannel analyzer detection system. The data was evaluated in 25 patients immediately before resection of a bladder tumor. Spectroscopic results were compared with histopathology. Upon 337 nm and 480 nm excitations, the overall intensity of the fluorescence spectra from bladder tumors was clearly reduced in comparison with normal urothelium, regardless of the stage and the grade of the tumor. upon 308 nm excitation, the shape of tumor fluorescence spectra, including carcinoma in situ, differed drastically from that of normal tissue. In this case, no absolute intensity measurements are needed and clear diagnosis can be achieved from fluorescence intensity ratio (360/440 nm). This spectroscopic study could be particularly useful for the design of a simplified autofluorescence imaging device for real-time routine detection of occult urothelial neoplastic lesions.

Diamond detectors for high-temperature transactinide chemistry experiments

NASA Astrophysics Data System (ADS)

Steinegger, Patrick; Dressler, Rugard; Eichler, Robert; Piguet, Dave; Streuli, Silvan; Türler, Andreas

2017-04-01

Here, we present the fabrication details and functional tests of diamond-based α-spectroscopic sensors, dedicated for high-temperature experiments, targeting the chemistry of transactinide elements. Direct heating studies with this sensor material, revealed a current upper temperature threshold for a safe α-spectroscopic operation of Tdet = 453 K . Up to this temperature, the diamond sensor could be operated in a stable manner over long time periods of the order of days. A satisfying resolution of ≈ 50 keVFWHM was maintained throughout all conducted measurements. However, exceeding the mentioned temperature limit led to a pronounced spectroscopic degradation in the range of 453 - 473 K , thereby preventing any further α-spectroscopic application. These findings are in full agreement with available literature data. The presented detector development generally enables the chemical investigation of more short-lived and less volatile transactinide elements and their compounds, yet unreachable with the currently employed silicon-based solid state sensors. In a second part, the design, construction, and α-spectroscopic performance of a 4-segmented diamond detector, dedicated and used for transactinide element research, is given as an application example.

Calibration Efforts and Unique Capabilities of the HST Space Telescope Imaging Spectrograph

NASA Astrophysics Data System (ADS)

Monroe, TalaWanda R.; Proffitt, Charles R.; Welty, Daniel; Branton, Doug; Carlberg, Joleen K.; debes, John Henry; Lockwood, Sean; Riley, Allyssa; Sohn, Sangmo Tony; Sonnentrucker, Paule G.; Walborn, Nolan R.; Jedrzejewski, Robert I.

2018-01-01

The Space Telescope Imaging Spectrograph (STIS) continues to offer the astronomy community the ability to carry out innovative UV and optical spectroscopic and imaging studies, two decades after its deployment on the Hubble Space Telescope (HST). Most notably, STIS provides spectroscopy in the FUV and NUV, including high spectral resolution echelle modes, imaging in the FUV, optical spectroscopy, and coronagraphic capabilities. Additionally, spatial scanning on the CCD with the long-slits is now possible to enable very high S/N spectroscopic observations without saturation while mitigating telluric and fringing concerns in the far red and near-IR. This new mode may especially benefit the diffuse interstellar bands and exoplanet transiting communities. We present recent calibration efforts for the instrument, including work to optimize the calibration of the echelle spectroscopic modes by improving the flux agreement of overlapping spectral orders affected by changes in the grating blaze function since HST Servicing Mission 4. We also discuss considerations to maintain the wavelength precision of the spectroscopic modes, and the current capabilities of CCD spectroscopic spatial trails.

Quantitative properties of clustering within modern microscopic nuclear models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Volya, A.; Tchuvil’sky, Yu. M., E-mail: tchuvl@nucl-th.sinp.msu.ru

2016-09-15

A method for studying cluster spectroscopic properties of nuclear fragmentation, such as spectroscopic amplitudes, cluster form factors, and spectroscopic factors, is developed on the basis of modern precision nuclear models that take into account the mixing of large-scale shell-model configurations. Alpha-cluster channels are considered as an example. A mathematical proof of the need for taking into account the channel-wave-function renormalization generated by exchange terms of the antisymmetrization operator (Fliessbach effect) is given. Examples where this effect is confirmed by a high quality of the description of experimental data are presented. By and large, the method in question extends substantially themore » possibilities for studying clustering phenomena in nuclei and for improving the quality of their description.« less

A high resolution spectroscopic study of the oxygen molecule. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Ritter, K. J.

1984-01-01

A high resolution spectrometer which incorporates a narrow line width tunable dye laser was used to make absorption profiles of 57 spectral lines in the Oxygen A-Band at pressures up to one atmosphere in pure O2. The observed line profiles are compared to the Voigt, and a collisionally narrowed, profile using a least squares fitting procedure. The collisionally narrowed profile compares more favorable to the observed profiles. Values of the line strengths and self broadening coeffiencients, determined from the least square fitting process, are presented in tabular form. It is found that the experssion by Watson are in closest agreement with the experimentally determined strengths. The self broadening coefficients are compared with the measurements of several other investigators.

Physics of the inner heliosphere: Mechanisms, models and observational signatures

NASA Technical Reports Server (NTRS)

Withbroe, G. L.

1985-01-01

The physics of the solar wind acceleration phenomena (e.g. effect of transient momentum deposition on the temporal and spatial variation of the temperature, density and flow speed of the solar wind, formation of shocks, etc.) and the resultant effects on observational signatures, particularly spectroscopic signature are studied. Phenomena under study include: (1) wave motions, particularly spectroscopic signatures are studied. Phenomena under study include:(1) wave motions, particularly Alfven and fast mode waves, (2) the formation of standing shocks in the inner heliosphere as a result of momentum and/or heat addition to the wind and (3) coronal transient phenomena where momentum and/or heat are deposited in the corona to produce transient plasma heating and/or mass ejections. Also included are the theoretical investigation of spectroscopic plasma diagnostics for the inner heliosphere and the analysis of existing Skylab and other relevant data.

In situ spectroscopic ellipsometry study of low-temperature epitaxial silicon growth

NASA Astrophysics Data System (ADS)

Halagačka, L.; Foldyna, M.; Leal, R.; Roca i Cabarrocas, P.

2018-07-01

Low-temperature growth of doped epitaxial silicon layers is a promising way to reduce the cost of p-n junction formation in c-Si solar cells. In this work, we study process of highly doped epitaxial silicon layer growth using in situ spectroscopic ellipsometry. The film was deposited by plasma-enhanced chemical vapor deposition (PECVD) on a crystalline silicon substrate at a low substrate temperature of 200 °C. In the deposition process, SiF4 was used as a precursor, B2H6 as doping gas, and a hydrogen/argon mixture as carrier gas. A spectroscopic ellipsometer with a wide spectral range was used for in situ spectroscopic measurements. Since the temperature during process is 200 °C, the optical functions of silicon differ from these at room temperature and have to be adjusted. Thickness of the epitaxial silicon layer was fitted on in situ ellipsometric data. As a result we were able to determine the dynamics of epitaxial layer growth, namely initial layer formation time and epitaxial growth rate. This study opens new perspectives in understanding and monitoring the epitaxial silicon deposition processes as the model fitting can be applied directly during the growth.

Calibration method for spectroscopic systems

DOEpatents

Sandison, David R.

1998-01-01

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.

Calibration method for spectroscopic systems

DOEpatents

Sandison, D.R.

1998-11-17

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

Abundance analysis of SDSS J134338.67+484426.6; an extremely metal-poor star from the MARVELS pre-survey

NASA Astrophysics Data System (ADS)

Susmitha Rani, A.; Sivarani, T.; Beers, T. C.; Fleming, S.; Mahadevan, S.; Ge, J.

2016-05-01

We present an elemental-abundance analysis of an extremely metal-poor (EMP; [Fe/H] <-3.0) star, SDSS J134338.67+484426.6, identified during the course of the Multi-object Apache Point Observatory Radial Velocity Exoplanet Large-area Survey spectroscopic pre-survey of some 20 000 stars to identify suitable candidates for exoplanet searches. This star, with an apparent magnitude V = 12.14, is the lowest metallicity star found in the pre-survey, and is one of only ˜20 known EMP stars that are this bright or brighter. Our high-resolution spectroscopic analysis shows that this star is a subgiant with [Fe/H] = -3.42, having `normal' carbon and no enhancement of neutron-capture abundances. Strontium is underabundant, [Sr/Fe] = -0.47, but the derived lower limit on [Sr/Ba] indicates that Sr is likely enhanced relative to Ba. This star belongs to the sparsely populated class of α-poor EMP stars that exhibit low ratios of [Mg/Fe], [Si/Fe], and [Ca/Fe] compared to typical halo stars at similar metallicity. The observed variations in radial velocity from several epochs of (low- and high-resolution) spectroscopic follow-up indicate that SDSS J134338.67+484426.6 is a possible long-period binary. We also discuss the abundance trends in EMP stars for r-process elements, and compare with other magnesium-poor stars.

Single-shot magnetic resonance spectroscopic imaging with partial parallel imaging.

PubMed

Posse, Stefan; Otazo, Ricardo; Tsai, Shang-Yueh; Yoshimoto, Akio Ernesto; Lin, Fa-Hsuan

2009-03-01

A magnetic resonance spectroscopic imaging (MRSI) pulse sequence based on proton-echo-planar-spectroscopic-imaging (PEPSI) is introduced that measures two-dimensional metabolite maps in a single excitation. Echo-planar spatial-spectral encoding was combined with interleaved phase encoding and parallel imaging using SENSE to reconstruct absorption mode spectra. The symmetrical k-space trajectory compensates phase errors due to convolution of spatial and spectral encoding. Single-shot MRSI at short TE was evaluated in phantoms and in vivo on a 3-T whole-body scanner equipped with a 12-channel array coil. Four-step interleaved phase encoding and fourfold SENSE acceleration were used to encode a 16 x 16 spatial matrix with a 390-Hz spectral width. Comparison with conventional PEPSI and PEPSI with fourfold SENSE acceleration demonstrated comparable sensitivity per unit time when taking into account g-factor-related noise increases and differences in sampling efficiency. LCModel fitting enabled quantification of inositol, choline, creatine, and N-acetyl-aspartate (NAA) in vivo with concentration values in the ranges measured with conventional PEPSI and SENSE-accelerated PEPSI. Cramer-Rao lower bounds were comparable to those obtained with conventional SENSE-accelerated PEPSI at the same voxel size and measurement time. This single-shot MRSI method is therefore suitable for applications that require high temporal resolution to monitor temporal dynamics or to reduce sensitivity to tissue movement.

Customizing model membranes and samples for NMR spectroscopic studies of complex membrane proteins.

PubMed

Sanders, C R; Oxenoid, K

2000-11-23

Both solution and solid state nuclear magnetic resonance (NMR) techniques for structural determination are advancing rapidly such that it is possible to contemplate bringing these techniques to bear upon integral membrane proteins having multiple transmembrane segments. This review outlines existing and emerging options for model membrane media for use in such studies and surveys the special considerations which must be taken into account when preparing larger membrane proteins for NMR spectroscopic studies.

PMMA and polystyrene films modification under ion implantation studied by spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Leontyev, A. V.; Kovalev, V. I.; Khomich, A. V.; Komarov, Fadei F.; Grigoryev, V. V.; Kamishan, A. S.

2004-05-01

We have applied spectroscopic ellipsometry with binary polarization modulation to study the refractive index n(λ) and extinction coefficient k(λ) spectra of as-deposited and irradiated with nitrogen ions polymethylmethacrylate (PMMA) and polystyrene (PS) films in 300-1030 nm range. The results of performed investigation confirmed the possibility and estimate restrictions of the ion implantation for local change the refractive index of polymeric materials.

Critical insight into the interaction of naringenin with human haemoglobin: A combined spectroscopic and computational modeling approaches

NASA Astrophysics Data System (ADS)

Maity, Subhajit; Chakraborty, Sandipan; Chakraborti, Abhay Sankar

2017-02-01

The present study demonstrates critical insight into the binding of a bioactive flavanone naringenin with normal human haemoglobin (NHb). Both spectrophotometric and spectrofluorimetric studies reveal that naringenin interacts with NHb. The binding affinity constant and number of binding sites appear to be approximately (1.5 ± 0.2) × 104 M-1 and 1, respectively. Static quenching seems to be an important factor in binding process, as evident from steady-state and time-resolved fluorescence spectroscopic studies. Far UV circular dichroism spectroscopy depicts that binding of naringenin to NHb causes no change in the secondary structure of the protein, which is also evident from Fourier transform infrared spectroscopic study. Free energy change (ΔG0) for naringenin-NHb interaction, determined by spectroscopic and isothermal calorimetric method, appears to be -5.67 kcal/mol and -6.90 kcal/mol, respectively, and is close to the docking energy -6.84 kcal/mol. Molecular docking suggests that naringenin binds near the cavity of the tetrameric heme protein, forming hydrogen bonds with surrounding amino acid residues. The binding site is away from the heme moieties, implicating naringenin binding does not affect the oxygen binding capacity of NHb, which makes the protein a suitable carrier of the flavonoid.

Relationships between astrogliosis and 1H MR spectroscopic measures of brain choline/creatine and myo-inositol/creatine in a primate model.

PubMed

Kim, John P; Lentz, Margaret R; Westmoreland, Susan V; Greco, Jane B; Ratai, Eva M; Halpern, Elkan; Lackner, Andrew A; Masliah, Eliezer; González, R Gilberto

2005-04-01

In vivo 1H MR spectroscopy demonstrates elevated choline (Cho)/creatine (Cr) and myo-inositol (MI)/Cr in many neurologic diseases that has been ascribed to gliosis. We tested the hypotheses that in vivo Cho/Cr and/or MI/Cr levels are correlated with glial fibrillary acidic protein (GFAP) immunostains and that the changes are water-soluble metabolites. We performed postmortem 1H MR spectroscopy and GFAP immunohistochemistry in brains from seven rhesus macaques acutely infected with simian immunodeficiency virus (SIV) and in four controls and compared the findings with previous in vivo MR spectroscopic results. Changes in neuropathologic and MR spectroscopic markers after infection and relationships among plasma viral load, GFAP immunostaining results, and ex vivo and in vivo MR spectroscopic measures were statistically evaluated. On GFAP immunostaining and in vivo MR spectroscopy, GFAP, Cho/Cr and MI/Cr were highest near the time of peak plasma viral load at 11 days postinfection (dpi). Immunostains returned to baseline by 14 dpi, whereas Cho/Cr and MI/Cr had different time courses, with the former dropping below baseline and the latter remaining elevated. Viral load and immunostains were significantly correlated. No correlation was found between ex vivo Cho/Cr or MI/Cr and viral load or between metabolite ratios from in vivo and ex vivo MR spectroscopy. In acute SIV infection, plasma viral load was significantly correlated with brain GFAP immunostains and in vivo 1H MR spectroscopic Cho/Cr. In vivo changes in Cho/Cr and MI/Cr were principally due to contributions other than those of low-molecular-weight water-soluble metabolites.

Introducing Students to a Synthetic and Spectroscopic Study of the Free Radical Chlorine Dioxide

ERIC Educational Resources Information Center

Sutton, Sarah C.; Cleland, Walter E.; Hammer, Nathan I.

2017-01-01

This advanced undergraduate chemistry laboratory exercise takes advantage of the unique spectroscopic properties of the free radical chlorine dioxide to allow for a direct comparison of its symmetric stretch in both the ground and excited states. It incorporates several subject areas covered in an undergraduate chemistry degree (synthesis,…

MULTISPECTRAL IDENTIFICATION OF POTENTIALLY HAZARDOUS BYPRODUCTS OF OZONATION AND CHLORINATION - PART I: STUDIES OF CHROMATOGRAPHIC AND SPECTROSCOPIC PROPERTIES OF MX

EPA Science Inventory

The gas chromatographic (GC) and Fourier transform infrared and mass spectroscopic (FT-IR and MS, respectively) properties of (Z)-2-chloro-3-(dichloromethyl)4-oxobutenoic acid (MX) (a highly mutagenic byproduct of drinking water chlorination) and several related compounds were st...

Study of spectroscopic properties of nanosized particles of core-shell morphology

NASA Astrophysics Data System (ADS)

Bzhalava, T. N.; Kervalishvili, P. J.

2018-03-01

Method of studying spectroscopic properties of nanosized particles and estimation of resonance wavelength range for determination of specific and unique “spectral” signatures in purpose of sensing, identification of nanobioparticles, viruses is proposed. Elaboration of relevant models of viruses, estimation of spectral response on interaction of electromagnetic (EM) field and viral nanoparticle is the goal of proposed methodology. Core-shell physical model is used as the first approximation of shape-structure of virion. Theoretical solution of EM wave scattering on single spherical virus-like particle (VLP) is applied for determination of EM fields in the areas of core, shell and surrounding medium of (VLP), as well as scattering and absorption characteristics. Numerical results obtained by computer simulation for estimation of EM “spectra” of bacteriophage T7 demonstrate the strong dependence of spectroscopic characteristics on core-shell related electric and geometric parameters of VLP in resonance wavelengths range. Expected spectral response is observable on far-field characterizations. Obtained analytical EM field expressions, modelling technique in complement with experimental spectroscopic methods should be the way of providing the virus spectral signatures, important in bioparticles characterization.

Measurements of Physical Parameters of White Dwarfs: A Test of the Mass–Radius Relation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bédard, A.; Bergeron, P.; Fontaine, G., E-mail: bedard@astro.umontreal.ca, E-mail: bergeron@astro.umontreal.ca, E-mail: fontaine@astro.umontreal.ca

We present a detailed spectroscopic and photometric analysis of 219 DA and DB white dwarfs for which trigonometric parallax measurements are available. Our aim is to compare the physical parameters derived from the spectroscopic and photometric techniques, and then to test the theoretical mass–radius relation for white dwarfs using these results. The agreement between spectroscopic and photometric parameters is found to be excellent, especially for effective temperatures, showing that our model atmospheres and fitting procedures provide an accurate, internally consistent analysis. The values of surface gravity and solid angle obtained, respectively, from spectroscopy and photometry, are combined with parallax measurementsmore » in various ways to study the validity of the mass–radius relation from an empirical point of view. After a thorough examination of our results, we find that 73% and 92% of the white dwarfs are consistent within 1 σ and 2 σ confidence levels, respectively, with the predictions of the mass–radius relation, thus providing strong support to the theory of stellar degeneracy. Our analysis also allows us to identify 15 stars that are better interpreted in terms of unresolved double degenerate binaries. Atmospheric parameters for both components in these binary systems are obtained using a novel approach. We further identify a few white dwarfs that are possibly composed of an iron core rather than a carbon/oxygen core, since they are consistent with Fe-core evolutionary models.« less

Nonlinear X-Ray and Auger Spectroscopy at X-Ray Free-Electron Laser Sources

NASA Astrophysics Data System (ADS)

Rohringer, Nina

2015-05-01

X-ray free-electron lasers (XFELs) open the pathway to transfer non-linear spectroscopic techniques to the x-ray domain. A promising all x-ray pump probe technique is based on coherent stimulated electronic x-ray Raman scattering, which was recently demonstrated in atomic neon. By tuning the XFEL pulse to core-excited resonances, a few seed photons in the spectral tail of the XFEL pulse drive an avalanche of resonant inelastic x-ray scattering events, resulting in exponential amplification of the scattering signal by of 6-7 orders of magnitude. Analysis of the line profile of the emitted radiation permits to demonstrate the cross over from amplified spontaneous emission to coherent stimulated resonance scattering. In combination with statistical covariance mapping, a high-resolution spectrum of the resonant inelastic scattering process can be obtained, opening the path to coherent stimulated x-ray Raman spectroscopy. An extension of these ideas to molecules and a realistic feasibility study of stimulated electronic x-ray Raman scattering in CO will be presented. Challenges to realizing stimulated electronic x-ray Raman scattering at present-day XFEL sources will be discussed, corroborated by results of a recent experiment at the LCLS XFEL. Due to the small gain cross section in molecular targets, other nonlinear spectroscopic techniques such as nonlinear Auger spectroscopy could become a powerful alternative. Theory predictions of a novel pump probe technique based on resonant nonlinear Auger spectroscopic will be discussed and the method will be compared to stimulated x-ray Raman spectroscopy.

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

DOE R&D Accomplishments Database

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

1987-02-01

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

Spectroscopic and Photometric Properties of Carbon Stars in the Disk of the Andromeda Galaxy

NASA Astrophysics Data System (ADS)

Guhathakurta, Puragra; Toloba, E.; Guha, S.; Rushing, C.; Dorman, C.; PHAT Collaboration; SPLASH Collaboration

2013-01-01

We explore the spectroscopic properties of a couple hundred carbon stars discovered in the disk of the Andromeda galaxy (M31) in the course of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) survey. The spectra were obtained using the DEIMOS spectrograph on the Keck II 10-meter telescope. About 5000 stars were targeted for spectroscopy during observing runs in 2010 and 2011 using DEIMOS's 1200 lines/mm grating with a spectral resolving power of R ~ 5000 to 6000 and spectral coverage from 6500-9000 Angstrom. In September 2012, another 5000 stars were observed this time with the 600 lines/mm grating and R ~ 2500 and spectral coverage from 4500-9000 Angstrom. For both types of spectroscopic observations, targets were selected from the Panchromatic Hubble Andromeda Treasury (PHAT) multi-cycle treasury program with the Hubble Space Telescope. Six-filter photometry in the ultraviolet (F275W, F336W), optical (F439W, F814W), and near infrared (F110W, F160W) is available for most targets. These carbon star samples are used to constrain the intermediage-age population in M31's disk. They are also compared to spectra of previously known carbon samples in the dwarf elliptical satellites of M31, NGC 147, NGC 185, and NGC 205. The authors thank the National Science Foundation, NASA/STScI, and UCSC's Summer Internship Program for support.

Vibrational spectroscopic study of terbutaline hemisulphate

NASA Astrophysics Data System (ADS)

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

2009-05-01

The Raman spectrum of terbutaline hemisulphate is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation; these predictions compare favourably with the observed vibrational spectra. Comparison with previously published infrared data explains several spectral features. The results from this study provide data that can be used for the preparative process monitoring of terbutaline hemisulphate, an important β 2 agonist drug in various dosage forms and its interaction with excipients and other components.

Infrared and Raman spectroscopic studies of structural variations in minerals from Apollo 11, 12, 14 and 15 samples, volume 3

NASA Technical Reports Server (NTRS)

Estep, P. A.; Kovach, J. J.; Waldstein, P.; Karr, C., Jr.

1972-01-01

Infrared and Raman vibrational spectroscopic data, yielding direct information on molecular structure, were obtained for single grains ( 150 microns) of minerals, basalts, and glasses isolated from Apollo 11, 12, 14, and 15 rock and dust samples, and for grains in Apollo 14 polished butt samples. From the vibrational data, specification substitutions were determined for the predominant silicate minerals of plagioclase, pyroxene, and olivine. Unique spectral variations for grains of K-feldspar, orthopyroxene, pyroxenoid, and ilmenite were observed to exceed the ranges of terrestrial samples, and these variations may be correlatable with formation histories. Alpha-quartz was isolated as pure single grains, in granitic grains composited with sanidine, and in unique grains that were intimately mixed with varying amounts of glass. Accessory minerals of chromite and ulvospinel were isolated as pure grains and structurally characterized from their distinctive infrared spectra. Fundamental vibrations of the SiO4 tetrahedra in silicate minerals were used to classify bulk compositions in dust sieved fractions, basalt grains and glass particles, and to compare modal characteristics for maria, highland and rille samples. No hydrated minerals were found in any of the samples studied, indicating anhydrous formation conditions.

Lyman-alpha fractions in the Hubble Ultra Deep Field at 4 < z < 6

NASA Astrophysics Data System (ADS)

Harish, Santosh; Malhotra, Sangeeta; Rhoads, James; Christensen, Lise; Tilvi, Vithal; Finkelstein, Steven; Pharo, John

2018-01-01

Lyman-alpha (Lya) emitting galaxies at high-redshifts serve as a good probe of neutral hydrogen in the intergalactic medium (IGM). Here we present measurements of the Lya fraction using a sample of Lyman-break galaxies (LBGs) between 4 < z < 6 with deep HST grism observations from the GRAPES/PEARS projects as well as spectroscopic observations from the MUSE integral-field spectrograph. The sample of LBGs at z~5 & 6 are spectroscopically confirmed with deep HST grism data from the GRAPES and PEARS projects. We also measure Lya fractions using a sample of photometrically-selected LBGs for the same redshift range. In addition, we study the EW distribution in relation to continuum and line luminosities, as well as the relation between photometric and spectroscopic redshift. We find that objects with higher EWs tend to have larger differences between photometric and spectroscopic redshifts.

Chemical and pharmacological comparison of modern and traditional dosage forms of Joshanda.

PubMed

Parveen, Sajida; Irfan Bukhari, Nadeem; Shehzadi, Naureen; Qamar, Shaista; Ali, Ejaz; Naheed, Surriya; Latif, Abida; Yuchi, Alamgeer; Hussain, Khalid

2017-12-11

Recently, a traditional remedy (Joshanda) has been replaced largely by modern ready-to-use dosage forms, which have not been compared to the original remedy. Therefore, the present study aimed to compare a number of modern dosage forms with traditional remedy. Seven brands, 3 batches each, were compared with a Lab-made formulation with reference to analytical (proximate analyses, spectroscopic and chromatographic metabolomes) and pharmacological profiles (anti-inflammatory and antibacterial activities). Chemical and pharmacological differences were found between Lab-made Joshanda and modern dosage forms. Such variations were also found within the brands and batches of modern formulations (p < 0.05). The Lab-made Joshanda showed significantly higher pharmacological activities as compared to modern brands (p ). The results of the present study indicate that modern dosage forms are unstandardised and less effective than the traditional remedy. Characteristic profiles obtained from Lab-made Joshanda may be used as reference to produce comparable dosage forms.

Experimental study of H2O spectroscopic parameters in the near-IR (6940 7440 cm-1) for gas sensing applications at elevated temperature

NASA Astrophysics Data System (ADS)

Liu, Xiang; Zhou, Xin; Jeffries, Jay B.; Hanson, Ronald K.

2007-02-01

Tunable diode laser (TDL) absorption sensors of water vapor are attractive for temperature, gas composition, velocity, pressure, and mass flux measurements in a variety of practical applications including hydrocarbon-fueled combustion systems. Optimized design of these sensors requires a complete catalog of the assigned transitions with accurate spectroscopic data; our particular interest has been in the 2ν1, 2ν3, and ν1+ν3 bands in the near-IR where telecommunications diode lasers are available. In support of this need, fully resolved absorption spectra of H2O vapor in the spectral range of 6940 7440 cm-1 (1344 1441 nm) have been measured as a function of temperature (296 1000 K) and pressure (1 800 Torr), and quantitative spectroscopic parameters inferred from these spectra compared to published data from Toth, HITRAN 2000 and HITRAN 2004. The peak absorbances were measured for more than 100 strong transitions at 296 and 828 K, and linestrengths determined for 47 strong lines in this region. In addition to reference linestrengths S(296 K), the air-broadening coefficients γair(296 K) and temperature exponents n were inferred for strong transitions in five narrow regions, near 7185.60, 7203.89, 7405.11, 7426.14 and 7435.62 cm-1 that had been targeted as attractive for future diagnostics applications. Most of the measured results, determined within an accuracy of 5%, are found to be in better agreement with HITRAN 2004 than with earlier editions of this database. Large discrepancies (>10%) between measurements and HITRAN 2004 database are identified for some of the probed transitions. These new spectroscopic data for H2O provide a useful test of the sensor design capabilities of HITRAN 2004 for combustion and other applications at elevated temperatures.

Mira variables: An informal review

NASA Technical Reports Server (NTRS)

Wing, R. F.

1980-01-01

The structure of the Mira variables is discussed with particular emphasis on the extent of their observable atmospheres, the various methods for measuring the sizes of these atmospheres, and the manner in which the size changes through the cycle. The results obtained by direct, photometric and spectroscopic methods are compared, and the problems of interpretation are addressed. Also, a simple model for the atmospheric structure and motions of Miras based on recent observations of the doubling of infrared molecualr times is described. This model, consisting of two atmospheric layers plus a circumstellar shell, provides a physically plausible picture of the atmosphere which is consistent with the photometrically measured magnitude and temperature variations as well as the spectroscopic data.

Broadband spectroscopic sensor for real-time monitoring of industrial SO(2) emissions.

PubMed

Xu, Feng; Zhang, Yungang; Somesfalean, Gabriel; Wang, Huashan; Wu, Shaohua; Zhang, Zhiguo

2007-05-01

A spectroscopic system for continuous real-time monitoring of SO(2) concentrations in industrial emissions was developed. The sensor is well suited for field applications due to simple and compact instrumental design, and robust data evaluation based on ultraviolet broadband absorption without the use of any calibration cell. The sensor has a detection limit of 1 ppm, and was employed both for gas-flow simulations with and without suspended particles, and for in situ measurement of SO(2) concentrations in the flue gas emitted from an industrial coal-fired boiler. The price/performance ratio of the instrument is expected to be superior to other comparable real-time monitoring systems.

Growth and spectroscopic properties of Sm3+:KY(WO4)2 crystal

NASA Astrophysics Data System (ADS)

Demesh, M. P.; Dernovich, O. P.; Gusakova, N. V.; Yasukevich, A. S.; Kornienko, A. A.; Dunina, E. B.; Fomicheva, L. A.; Pavlyuk, A. A.; Kuleshov, N. V.

2018-01-01

A Sm3+:KY(WO4)2 crystal was grown by the modified Czochralski technique. Polarized absorption and fluorescence spectra, as well as a fluorescence decay curve, were recorded at room temperature. Radiative properties such as emission probabilities, branching ratios and radiative lifetimes were investigated within the framework of the Judd-Ofelt theory as well as the theory of f-f transition intensities which takes into account the influence of the excited configurations. Emission cross section spectra were determined. 4G5/2 fluorescence decay was analyzed within the framework of the Inokuti-Hirayama model. The spectroscopic properties of Sm:KYW crystal were compared with those of other Sm3+-doped materials.

Spectroscopic evidence of α,α-dichlorobenzyl radical produced by corona discharge of benzotrichloride

NASA Astrophysics Data System (ADS)

Yoon, Young Wook; Chae, Sang Youl; Lim, Manho; Lee, Sang Kuk

2015-08-01

We report spectroscopic observations of the α,α-dichlorobenzyl radical obtained by corona excited supersonic jet expansion using a pinhole-type glass nozzle. Vibronically excited but jet-cooled radicals were generated by corona discharge of the precursor benzotrichloride with a large amount of helium carrier gas, from which the visible vibronic emission spectrum was recorded using a long path monochromator. From an analysis of the spectrum observed, the electronic energy of the D1 → D0 transition and a few vibrational mode frequencies in the ground electronic state were obtained for the α,α-dichlorobenzyl radical by comparing observed frequencies with those obtained by ab initio calculation.

Initial results of 3-dimensional 1H-magnetic resonance spectroscopic imaging in the localization of prostate cancer at 3 Tesla: should we use an endorectal coil?

PubMed

Yakar, Derya; Heijmink, Stijn W T P J; Hulsbergen-van de Kaa, Christina A; Huisman, Henkjan; Barentsz, Jelle O; Fütterer, Jurgen J; Scheenen, Tom W J

2011-05-01

The purpose of this study was to compare the diagnostic performance of 3 Tesla, 3-dimensional (3D) magnetic resonance spectroscopic imaging (MRSI) in the localization of prostate cancer (PCa) with and without the use of an endorectal coil (ERC). Our prospective study was approved by the institutional review board, and written informed consent was obtained from all patients. Between October 2004 and January 2006, 18 patients with histologically proven PCa on biopsy and scheduled for radical prostatectomy were included and underwent 3D-MRSI with and without an ERC. The prostate was divided into 14 regions of interest (ROIs). Four readers independently rated (on a 5-point scale) their confidence that cancer was present in each of these ROIs. These findings were correlated with whole-mount prostatectomy specimens. Areas under the receiver-operating characteristic curve were determined. A difference with a P < 0.05 was considered significant. A total of 504 ROIs were rated for the presence and absence of PCa. Localization of PCa with MRSI with the use of an ERC had a significantly higher areas under the receiver-operating characteristic curve (0.68) than MRSI without the use of an ERC (0.63) (P = 0.015). The use of an ERC in 3D MRSI in localizing PCa at 3 Tesla slightly but significantly increased the localization performance compared with not using an ERC.

Synthesis, characterization, crystal structure and quantum chemical investigations of three novel coumarin-benzenesulfonohydrazide derivatives

NASA Astrophysics Data System (ADS)

Chethan Prathap, K. N.; Lokanath, N. K.

2018-04-01

Coumarin derivatives are an important class of heterocyclic compounds due to their physical and biological properties. Coumarin derivatives have been identified with many significant electro-optical properties and biological activities. Three novel coumarin derivatives containing benzene sulfonohydrazide group were synthesized by condensation reaction. The synthesized compounds were characterized by various spectroscopic techniques (Mass, 1H/13C NMR and FTIR). Thermal and optical properties were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and UV-Vis spectroscopic studies. Finally their structures were confirmed by single crystal X-ray diffraction (XRD) studies. The three compounds exhibit diverse intermolecular interactions, as observed by the crystal packing and Hirshfeld surface analysis. Further, their structures were optimized by density functional theory (DFT) calculations using B3LYP hybrid functionals with 6-311G+(d,p) level basis set. The Mulliken charge, molecular electrostatic potential (MEP), frontier molecular orbitals (HOMO-LUMO) were investigated. The experimentally determined parameters were compared with those calculated theoretically and they complement each other with a very good correlation. The transitions among the molecular orbitals were investigated using time-dependent density functional theory (TD-DFT) and the electronic absorption spectra obtained showed very good agreement with the experimentally measured UV-Vis spectra. Furthermore, non-linear optical (NLO) properties were investigated by calculating polarizabilities and hyperpolarizabilities. All three compounds exhibit significantly high hyperpolarizabilities compared to the reference material urea, which makes them potential candidates for NLO applications.

Spectroscopic, molecular docking and structural activity studies of (E)-N‧-(substituted benzylidene/methylene) isonicotinohydrazide derivatives for DNA binding and their biological screening

NASA Astrophysics Data System (ADS)

Arshad, Nasima; Perveen, Fouzia; Saeed, Aamer; Channar, Pervaiz Ali; Farooqi, Shahid Iqbal; Larik, Fayaz Ali; Ismail, Hammad; Mirza, Bushra

2017-07-01

Acid catalyzed condensation of isoniazid with a number of suitably substituted aromatic and heterocyclic aldehydes was carried out in dry ethanol to afford the title (E)-N‧-(substituted benzylidene/methylene) isonicotinohydrazides (SF 1 - SF 4) in good yields. These compounds were characterized and further investigated for their binding with ds.DNA using UV- spectroscopy and molecular docking and for antitumor and antimicrobial potentials. A good correlation was found among spectroscopic, theoretical and biological results. UV- spectra in the presence of DNA concentrations and their data interpretation in terms binding constant "Kb" and free energy change (ΔG) provided evidences for the significant and spontaneous binding of the compounds with DNA. Molecular docking studies and structural analysis further supported the UV-findings and indicated that the modes of interactions between bromo- (SF 1) and flouro- (SF 4) substituted isonicotinohydrazides is intercalation while methoxy- (SF 2) and hydroxy- (SF 3) substituted isonicotinohydrazides interact with DNA helix via groove binding. SF 1 exhibited comparatively higher Kb value (UV-; 8.07 × 103 M-1, docking; 8.11 × 103 M-1) which inferred that the respective compound muddles to DNA most powerfully. SF 1 has shown the lowest IC50 (345.3 μg/mL) value among all the compounds indicating its comparatively highest activity towards tumor inhibition. None of the compound has shown perceptible antibacterial and antifungal activities.

Short- and long-term quantitation reproducibility of brain metabolites in the medial wall using proton echo planar spectroscopic imaging.

PubMed

Tsai, Shang-Yueh; Lin, Yi-Ru; Wang, Woan-Chyi; Niddam, David M

2012-11-15

Proton echo planar spectroscopic imaging (PEPSI) is a fast magnetic resonance spectroscopic imaging (MRSI) technique that allows mapping spatial metabolite distributions in the brain. Although the medial wall of the cortex is involved in a wide range of pathological conditions, previous MRSI studies have not focused on this region. To decide the magnitude of metabolic changes to be considered significant in this region, the reproducibility of the method needs to be established. The study aims were to establish the short- and long-term reproducibility of metabolites in the right medial wall and to compare regional differences using a constant short-echo time (TE30) and TE averaging (TEavg) optimized to yield glutamatergic information. 2D sagittal PEPSI was implemented at 3T using a 32 channel head coil. Acquisitions were repeated immediately and after approximately 2 weeks to assess the coefficients of variation (COV). COVs were obtained from eight regions-of-interest (ROIs) of varying size and location. TE30 resulted in better spectral quality and similar or lower quantitation uncertainty for all metabolites except glutamate (Glu). When Glu and glutamine (Gln) were quantified together (Glx) reduced quantitation uncertainty and increased reproducibility was observed for TE30. TEavg resulted in lowered quantitation uncertainty for Glu but in less reliable quantification of several other metabolites. TEavg did not result in a systematically improved short- or long-term reproducibility for Glu. The ROI volume was a major factor influencing reproducibility. For both short- and long-term repetitions, the Glu COVs obtained with TEavg were 5-8% for the large ROIs, 12-17% for the medium sized ROIs and 16-26% for the smaller cingulate ROIs. COVs obtained with TE30 for the less specific Glx were 3-5%, 8-10% and 10-15%. COVs for N-acetyl aspartate, creatine and choline using TE30 with long-term repetition were between 2-10%. Our results show that the cost of more specific glutamatergic information (Glu versus Glx) is the requirement of an increased effect size especially with increasing anatomical specificity. This comes in addition to the loss of sensitivity for other metabolites. Encouraging results were obtained with TE30 compared to other previously reported MRSI studies. The protocols implemented here are reliable and may be used to study disease progression and intervention mechanisms. Copyright © 2012 Elsevier Inc. All rights reserved.

Evidence for Cluster Evolution from an Improved Measurement of the Velocity Dispersion and Morphological Fraction of Cluster 1324+3011 at z=0.76

NASA Astrophysics Data System (ADS)

Lubin, Lori M.; Oke, J. B.; Postman, Marc

2002-10-01

We have carried out additional spectroscopic observations in the field of cluster Cl 1324+3011 at z=0.76. Combined with the spectroscopy recently presented by Postman, Lubin, & Oke, we now have spectroscopically confirmed 47 cluster members. With this significant number of redshifts, we measure accurately the cluster velocity dispersion to be 1016+126-93 km s-1. The distribution of velocity offsets is consistent with a Gaussian, indicating no substantial velocity substructure. As previously noted for other optically selected clusters at redshifts of z>~0.5, a comparison between the X-ray luminosity (LX) and the velocity dispersion (σ) of Cl 1324+3011 implies that this cluster is underluminous in X-rays by a factor of ~3-40 when compared with the LX-σ relation for local and moderate-redshift clusters. We also examine the morphologies of those cluster members that have available high angular resolution imaging with the Hubble Space Telescope (HST). There are 22 spectroscopically confirmed cluster members within the HST field of view. Twelve of these are visually classified as early-type (elliptical or S0) galaxies, implying an early-type fraction of 0.55+0.17-0.14 in this cluster. This fraction is a factor of ~1.5 lower than that observed in nearby rich clusters. Confirming previous cluster studies, the results for cluster Cl 1324+3011, combined with morphological studies of other massive clusters at redshifts of 0<=z<~1, suggest that the galaxy population in massive clusters is strongly evolving with redshift. This evolution implies that early-type galaxies are forming out of the excess of late-type (spiral, irregular, and peculiar) galaxies over the ~7 Gyr timescale.

In-situ Probing of Radiation-induced Processing of Organics in Astrophysical Ice Analogs—Novel Laser Desorption Laser Ionization Time-of-flight Mass Spectroscopic Studies

NASA Astrophysics Data System (ADS)

Gudipati, Murthy S.; Yang, Rui

2012-09-01

Understanding the evolution of organic molecules in ice grains in the interstellar medium (ISM) under cosmic rays, stellar radiation, and local electrons and ions is critical to our understanding of the connection between ISM and solar systems. Our study is aimed at reaching this goal of looking directly into radiation-induced processing in these ice grains. We developed a two-color laser-desorption laser-ionization time-of-flight mass spectroscopic method (2C-MALDI-TOF), similar to matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectroscopy. Results presented here with polycyclic aromatic hydrocarbon (PAH) probe molecules embedded in water-ice at 5 K show for the first time that hydrogenation and oxygenation are the primary chemical reactions that occur in astrophysical ice analogs when subjected to Lyα radiation. We found that hydrogenation can occur over several unsaturated bonds and the product distribution corresponds to their stabilities. Multiple hydrogenation efficiency is found to be higher at higher temperatures (100 K) compared to 5 K—close to the interstellar ice temperatures. Hydroxylation is shown to have similar efficiencies at 5 K or 100 K, indicating that addition of O atoms or OH radicals to pre-ionized PAHs is a barrierless process. These studies—the first glimpses into interstellar ice chemistry through analog studies—show that once accreted onto ice grains PAHs lose their PAH spectroscopic signatures through radiation chemistry, which could be one of the reason for the lack of PAH detection in interstellar ice grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks.

Spectroscopic detection, characterization and dynamics of free radicals relevant to combustion processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Terry

2015-06-04

Combustion chemistry is enormously complex. The chemical mechanisms involve a multitude of elementary reaction steps and a comparable number of reactive intermediates, many of which are free radicals. Computer simulations based upon these mechanisms are limited by the validity of the mechanisms and the parameters characterizing the properties of the intermediates and their reactivity. Spectroscopy can provide data for sensitive and selective diagnostics to follow their reactions. Spectroscopic analysis also provides detailed parameters characterizing the properties of these intermediates. These parameters serve as experimental gold standards to benchmark predictions of these properties from large-scale, electronic structure calculations. This work hasmore » demonstrated the unique capabilities of near-infrared cavity ringdown spectroscopy (NIR CRDS) to identify, characterize and monitor intermediates of key importance in complex chemical reactions. Our studies have focussed on the large family of organic peroxy radicals which are arguably themost important intermediates in combustion chemistry and many other reactions involving the oxidation of organic compounds. Our spectroscopic studies have shown that the NIR Ã - ˜X electronic spectra of the peroxy radicals allows one to differentiate among chemical species in the organic peroxy family and also determine their isomeric and conformic structure in many cases. We have clearly demonstrated this capability on saturated and unsaturated peroxy radicals and β-hydroxy peroxy radicals. In addition we have developed a unique dual wavelength CRDS apparatus specifically for the purpose of measuring absolute absorption cross section and following the reaction of chemical intermediates. The utility of the apparatus has been demonstrated by measuring the cross-section and self-reaction rate constant for ethyl peroxy.« less

Uranium(VI) Binding Forms in Selected Human Body Fluids: Thermodynamic Calculations versus Spectroscopic Measurements.

PubMed

Osman, Alfatih A A; Geipel, Gerhard; Barkleit, Astrid; Bernhard, Gert

2015-02-16

Human exposure to uranium increasingly becomes a subject of interest in many scientific disciplines such as environmental medicine, toxicology, and radiation protection. Knowledge about uranium chemical binding forms(speciation) in human body fluids can be of great importance to understand not only its biokinetics but also its relevance in risk assessment and in designing decorporation therapy in the case of accidental overexposure. In this study, thermodynamic calculations of uranium speciation in relevant simulated and original body fluids were compared with spectroscopic data after ex-situ uranium addition. For the first time, experimental data on U(VI) speciation in body fluids (saliva, sweat, urine) was obtained by means of cryogenic time-resolved laser-induced fluorescence spectroscopy (cryo-TRLFS) at 153 K. By using the time dependency of fluorescence decay and the band positions of the emission spectra, various uranyl complexes were demonstrated in the studied samples. The variations of the body fluids in terms of chemical composition, pH, and ionic strength resulted in different binding forms of U(VI). The speciation of U(VI) in saliva and in urine was affected by the presence of bioorganic ligands, whereas in sweat, the distribution depends mainly on inorganic ligands. We also elucidated the role of biological buffers, i.e., phosphate (H(2)PO(4−)/HPO(4)(2−)) on U(VI) distribution, and the system Ca(2+)/UO(2)(2+)/PO(4)(3−) was discussed in detail in both saliva and urine. The theoretical speciation calculations of the main U(VI) species in the investigated body fluids were significantly consistent with the spectroscopic data. Laser fluorescence spectroscopy showed success and reliability for direct determination of U(VI) in such biological matrices with the possibility for further improvement.

EBIT spectroscopy of highly charged heavy ions relevant to hot plasmas

NASA Astrophysics Data System (ADS)

Nakamura, Nobuyuki

2013-05-01

An electron beam ion trap (EBIT) is a versatile device for studying highly charged ions. We have been using two types of EBITs for the spectroscopic studies of highly charged ions. One is a high-energy device called the Tokyo-EBIT, and another is a compact low-energy device called CoBIT. Complementary use of them enables us to obtain spectroscopic data for ions over a wide charge-state range interacting with electrons over a wide energy range. In this talk, we present EBIT spectra of highly charged ions for tungsten, iron, bismuth, etc., which are relevant to hot plasmas. Tungsten is considered to be the main impurity in the ITER (the next generation nuclear fusion reactor) plasma, and thus its emission lines are important for diagnosing and controlling the ITER plasma. We have observed many previously unreported lines to supply the lack of spectroscopic data of tungsten ions. Iron is one of the main components of the solar corona, and its spectra are used to diagnose temperature, density, etc. The diagnostics is usually done by comparing observed spectra with model calculations. An EBIT can provide spectra under a well-defined condition; they are thus useful to test the model calculations. Laser-produced bismuth plasma is one of the candidates for a soft x-ray source in the water window region. An EBIT has a narrow charge state distribution; it is thus useful to disentangle the spectra of laser-produced plasma containing ions with a wide charge-state range. Performed with the support and under the auspices of the NIFS Collaboration Research program (NIFS09KOAJ003) and JSPS KAKENHI Number 23246165, and partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics.

Spectroscopic Characteristic and Analytical Capability of Ar-N₂ Inductively Coupled Plasma in Axially Viewing Optical Emission Spectrometry.

PubMed

Ohata, Masaki

2016-01-01

The spectroscopic characteristics and analytical capability of argon-nitrogen (Ar-N2) inductively coupled plasma (ICP) in axially viewing optical emission spectrometry (OES) were examined and figures of merit were determined in the present study. The spectroscopic characteristics such as the emission intensity profile and the excitation temperature observed from the analytical zone of Ar-N2 ICP in axially viewing ICPOES, in order to elucidate the enhancement of the emission intensity of elements obtained in our previous study, were evaluated and compared to those of the standard ICP. The background and emission intensities of elements as well as their excitation behavior for both atom and ion lines were also examined. As results, a narrower emission intensity profile and an increased excitation temperature as well as enhancements for both background and emission intensities of elements, which could be due to the ICP shrunken as well as the enhancement of the interaction between the central channel of the ICP and samples introduced, were observed for Ar-N2 ICP in axially viewing OES. In addition, the elements with relatively higher excitation and ionization energies such as As, Bi, Cd, Ni, P, and Zn revealed larger enhancements of the emission intensities as well as improved limits of detection (LODs), which were also attributed to the enhanced interaction between Ar-N2 ICP and the samples. Since the Ar-N2 ICP could be obtained easily only by the addition of a small amount of N2 gas to the Ar plasma gas of the standard ICP and no optimization on the alignment between Ar-N2 ICP and the spectrometer in commercially available ICPOES instruments was needed, it could be utilized as simple and optional excitation and ionization sources in axially viewing ICPOES.

Measuring the Spectral Properties of Candidate Mineral Sources of the Venus Radar Anomalies

NASA Astrophysics Data System (ADS)

Kohler, E.; Maturilli, A.; Koulen, J.; Helbert, J.

2016-12-01

Radar mapping of the surface of Venus shows areas of high reflectivity (low emissivity) in the Venusian highlands at altitudes between 2.5-4.75 kilometers. The origin of the radar anomalies found in the highlands remains unclear. Previous experimental research investigated possible materials under simulated Venusian atmospheric and surface conditions, with special emphasis on the combined effect of pressure and temperature, and chemical composition. The results of these studies identified candidate source materials for the radar anomalies. In order to fully be considered a true source candidate the material must have spectroscopic measurements comparable to those measured on the surface of Venus where the high temperature affects spectral characteristics of minerals. The spectroscopic measurements of the previously identified candidate minerals were made at the Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin in an effort to identify the anomaly source. The spectroscopic measurements were made with a FTIR Bruker Vertex 80V evacuated to .1 mbar and using several pairings of detector+beamsplitter to cover the spectral range from 0.2 to 20 µm. Each sample was poured in a stainless steel reflectance cup and measured fresh. Successively each cup was heated (via an induction system) in vacuum (0.07 mbar) at 400°C for 8 hours and measured again in the UV+VIS+MIR spectral range. Three consecutive cycles of heating and measuring reflectance were performed to account for spectral variations arising from the thermal processing of the samples. Heating the samples directly inside the reflectance cups allows to measure every time exactly the same surface, exposed to increasing levels of thermal processing. Results from this study are expected to further constrain the source of the Venus radar anomalies.

Physical and Mathematical Methods for Removing Organic Interference from Optical Isotope Measurements

NASA Astrophysics Data System (ADS)

Hsiao, G.; Chappellet-Volini, L.; Vu, D.

2012-12-01

Portable high precision isotope analyzers using CRDS technology have greatly increased the use of stable isotopes in hydrological, oceanographic, and ecological studies over the past five years. However studies of some water samples yielded incorrect isotopic values indicating some form of spectroscopic interference. Subsequent work has shown that waters derived from some plants containing interfering alcohols but meteoric waters are not affected. The initial approach to handling such samples was to use spectroscopic anomalies to identify and flag affected samples for later analysis by non-optical methods. This presentation will examine the approaches developed within the past year to allow for accurate analysis of such samples by optical methods. The first approach uses an advanced spectroscopic model to identify and quantify alcohols present in the sample. The alcohol signal is incorporated into the overall fit of the measure spectra to calculate the concentration of the individual isotopes. It was found that the δ18O value could be calculated with high accuracy, the result for the δ2H value was sufficient for many applications. The second approach uses physical treatment of the sample to break down the organic molecules into non-interfering species. The liquid sample is injected into a flash vaporizer then the vapor travels through a cartridge for physical treatment prior to analysis by CRDS. Inside the cartridge the organic molecules undergo oxidation at high temperature in the air carrier gas when exposed to the catalyst. This approach is highly effective for ethanol solutions as high as 5% as well as for the complex mixtures of alcohols found in plants. Comparison of the results of both of these methods will be compared with tertiary techniques such as IRMS where possible.

Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flesch, K.; Kremeyer, T.; Schmitz, O.

Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D-2 molecules and the He ash which will be produced by deuterium-tritium fusion. In order to study He exhaust, an in situ Penning gauge system is being developed at UW-Madison that is optimized for good pressure and high spectroscopic sensitivity. There are three different anode geometries that we have studied regarding their vacuum electrostatic fields, light output, and ion current. The light output of the two new anode configurations are at least onemore » order of magnitude above the currently available designs, hence improving the spectroscopic sensitivity at similar total neutral pressure resolution.« less

Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flesch, K., E-mail: kbflesch@wisc.edu; Kremeyer, T.; Schmitz, O.

Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D{sub 2} molecules and the He ash which will be produced by deuterium-tritium fusion. To study He exhaust, an in situ Penning gauge system is being developed at UW-Madison that is optimized for good pressure and high spectroscopic sensitivity. Three different anode geometries have been studied regarding their vacuum electrostatic fields, light output, and ion current. The light output of the two new anode configurations are at least one order of magnitude abovemore » the currently available designs, hence improving the spectroscopic sensitivity at similar total neutral pressure resolution.« less

Spectroscopic study of non-amphiphilic 2-(4-biphenylyl)-5-(4- tert-butylphenyl)-l,3,4-oxadiazole aggregates at air-water interface and in Langmuir-Blodgett films

NASA Astrophysics Data System (ADS)

Acharya, Somobrata; Bhattacharjee, D.; Sarkar, Jyotirmoy; Talapatra, G. B.

2004-07-01

This Letter reports the spectroscopic characteristics of a non-amphiphilic 2-(4-biphenylyl)-5-(4- tert-butylphenyl)-1,3,4-oxadiazole (buPBD) molecule, in Langmuir and Langmuir-Blodgett (LB) films mixed with polymethyl methacrylate (PMMA) as well as with arachidic acid (AA). The π- A isotherms of buPBD mixed with PMMA/AA at different molefractions show that at very low surface pressure, a phase transition corresponding to a reorientation of the buPBD molecules occur, whereas at high surface pressure, buPBD molecules form aggregates among the hydrophobic tail part of PMMA/AA. Absorption and fluorescence spectroscopic study of the mixed LB films reveal formation of different types of aggregates.

Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements

DOE PAGES

Flesch, K.; Kremeyer, T.; Schmitz, O.; ...

2016-08-18

Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D-2 molecules and the He ash which will be produced by deuterium-tritium fusion. In order to study He exhaust, an in situ Penning gauge system is being developed at UW-Madison that is optimized for good pressure and high spectroscopic sensitivity. There are three different anode geometries that we have studied regarding their vacuum electrostatic fields, light output, and ion current. The light output of the two new anode configurations are at least onemore » order of magnitude above the currently available designs, hence improving the spectroscopic sensitivity at similar total neutral pressure resolution.« less

Surface-enhanced Raman spectroscopic and surface plasmon resonance in situ study of self-assembly of 4-mercaptobenzoic acid on gold surface

NASA Astrophysics Data System (ADS)

Thi, Minh Do; Volka, Karel

2010-07-01

A feasibility study has been undertaken to assess the suitability of a commercially available SERS substrate for monitoring of self-assembling deposition process. Monolayer self-assembly of 4-mercaptobenzoic acid on SERS active substrate Klarite™ from absolute and acidified ethanol was studied and compared with deposition on SPR substrate from absolute ethanol. Changes in integral intensity of the phenyl bands at 1587 and 1076 cm -1 and ethanol band at 1451 cm -1 allow to follow structural changes in the monolayer. Stability of the monolayer assembled from acidified ethanol in contrast to the pure ethanol was demonstrated.

Mossbauer spectroscopic studies in ferroboron

NASA Astrophysics Data System (ADS)

Yadav, Ravi Kumar; Govindaraj, R.; Amarendra, G.

2017-05-01

Mossbauer spectroscopic studies have been carried out in a detailed manner on ferroboron in order to understand the local structure and magnetic properties of the system. Evolution of the local structure and magnetic properties of the amorphous and crystalline phases and their thermal stability have been addressed in a detailed manner in this study. Role of bonding between Fe 4s and/or 4p electrons with valence electrons of boron (2s,2p) in influencing the stability and magnetic properties of Fe-B system is elucidated.

Systematic Comparison of Photoionized Plasma Codes with Application to Spectroscopic Studies of AGN in X-Rays

NASA Technical Reports Server (NTRS)

Mehdipour, M.; Kaastra, J. S.; Kallman, T.

2016-01-01

Atomic data and plasma models play a crucial role in the diagnosis and interpretation of astrophysical spectra, thus influencing our understanding of the Universe. In this investigation we present a systematic comparison of the leading photoionization codes to determine how much their intrinsic differences impact X-ray spectroscopic studies of hot plasmas in photoionization equilibrium. We carry out our computations using the Cloudy, SPEX, and XSTAR photoionization codes, and compare their derived thermal and ionization states for various ionizing spectral energy distributions. We examine the resulting absorption-line spectra from these codes for the case of ionized outflows in active galactic nuclei. By comparing the ionic abundances as a function of ionization parameter, we find that on average there is about 30 deviation between the codes in where ionic abundances peak. For H-like to B-like sequence ions alone, this deviation in is smaller at about 10 on average. The comparison of the absorption-line spectra in the X-ray band shows that there is on average about 30 deviation between the codes in the optical depth of the lines produced at log 1 to 2, reducing to about 20 deviation at log 3. We also simulate spectra of the ionized outflows with the current and upcoming high-resolution X-ray spectrometers, on board XMM-Newton, Chandra, Hitomi, and Athena. From these simulations we obtain the deviation on the best-fit model parameters, arising from the use of different photoionization codes, which is about 10 to40. We compare the modeling uncertainties with the observational uncertainties from the simulations. The results highlight the importance of continuous development and enhancement of photoionization codes for the upcoming era of X-ray astronomy with Athena.

A comparative study on the binding of single and double chain surfactant-cobalt(III) complexes with bovine serum albumin

NASA Astrophysics Data System (ADS)

Vignesh, G.; Sugumar, K.; Arunachalam, S.; Vignesh, S.; Arthur James, R.

2013-09-01

The comparative binding effect of single and double aliphatic chain containing surfactant-cobalt(III) complexes cis-[Co(bpy)2(DA)2](ClO4)3ṡ2H2O (1), cis-[Co(bpy)2(DA)Cl](ClO4)2ṡ2H2O (2), cis-[Co(phen)2(CA)2](ClO4)3ṡ2H2O (3), and cis-[Co(phen)2(CA)Cl](ClO4)2ṡ2H2O (4) with bovine serum albumin (BSA) under physiological condition was analyzed by steady state, time resolved fluorescence, synchronous, three-dimensional fluorescence, UV-Visible absorption and circular dichroism spectroscopic techniques. The results show that these complexes cause the fluorescence quenching of BSA through a static mechanism. The binding constants (Kb) and the number of binding sites were calculated and binding constant values are found in the range of 104-105 M-1. The results indicate that compared to single chain complex, double chain surfactant-cobalt(III) complex interacts strongly with BSA. Also the sign of thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicate that all the complexes interact with BSA through hydrophobic force. The binding distance (r) between complexes and BSA was calculated using Förster non-radiation energy transfer theory and found to be less than 7 nm. The results of synchronous, three dimensional fluorescence and circular dichroism spectroscopic methods indicate that the double chain surfactant-cobalt(III) complexes changed the conformation of the protein considerably than the respective single chain surfactant-cobalt(III) complexes. Antimicrobial studies of the complexes showed good activities against pathogenic microorganisms.

Comparison between infrared and Raman spectroscopic analysis of maturing rabbit cortical bone.

PubMed

Turunen, Mikael J; Saarakkala, Simo; Rieppo, Lassi; Helminen, Heikki J; Jurvelin, Jukka S; Isaksson, Hanna

2011-06-01

The molecular composition of the organic and inorganic matrices of bone undergoes alterations during maturation. The aim of this study was to compare Fourier transform infrared (FT-IR) and near-infrared (NIR) Raman microspectroscopy techniques for characterization of the composition of growing and developing bone from young to skeletally mature rabbits. Moreover, the specificity and differences of the techniques for determining bone composition were clarified. The humeri of female New Zealand White rabbits, with age range from young to skeletally mature animals (four age groups, n = 7 per group), were studied. Spectral peak areas, intensities, and ratios related to organic and inorganic matrices of bone were analyzed and compared between the age groups and between FT-IR and Raman microspectroscopic techniques. Specifically, the degree of mineralization, type-B carbonate substitution, crystallinity of hydroxyapatite (HA), mineral content, and collagen maturity were examined. Significant changes during maturation were observed in various compositional parameters with one or both techniques. Overall, the compositional parameters calculated from the Raman spectra correlated with analogous parameters calculated from the IR spectra. Collagen cross-linking (XLR), as determined through peak fitting and directly from the IR spectra, were highly correlated. The mineral/matrix ratio in the Raman spectra was evaluated with multiple different peaks representing the organic matrix. The results showed high correlation with each other. After comparison with the bone mineral density (BMD) values from micro-computed tomography (micro-CT) imaging measurements and crystal size from XRD measurements, it is suggested that Raman microspectroscopy is more sensitive than FT-IR microspectroscopy for the inorganic matrix of the bone. In the literature, similar spectroscopic parameters obtained with FT-IR and NIR Raman microspectroscopic techniques are often compared. According to the present results, however, caution is required when performing this kind of comparison.

Pulsed electrical discharge in gas bubbles in water

NASA Astrophysics Data System (ADS)

Gershman, Sophia

A phenomenological picture of pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying one microsecond long 5 to 20 kilovolt pulses between the needle and disk electrodes submerged in water. A gas bubble is generated at the tip of the needle electrode. The study includes detailed experimental investigation of the discharge in argon bubbles and a brief look at the discharge in oxygen bubbles. Imaging, electrical characteristics, and time-resolved optical emission data point to a fast streamer propagation mechanism and formation of a plasma channel in the bubble. Spectroscopic methods based on line intensity ratios and Boltzmann plots of line intensities of argon, atomic hydrogen, and argon ions and the examination of molecular emission bands from molecular nitrogen and hydroxyl radicals provide evidence of both fast beam-like electrons and slow thermalized ones with temperatures of 0.6 -- 0.8 electron-volts. The collisional nature of plasma at atmospheric pressure affects the decay rates of optical emission. Spectroscopic study of rotational-vibrational bands of hydroxyl radical and molecular nitrogen gives vibrational and rotational excitation temperatures of the discharge of about 0.9 and 0.1 electron-volt, respectively. Imaging and electrical evidence show that discharge charge is deposited on the bubble wall and water serves as a dielectric barrier for the field strength and time scales of this experiment. Comparing the electrical and imaging information for consecutive pulses applied at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from long-lived chemical species, such as ozone and oxygen. Intermediate values for the discharge gap and pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique compared to the traditional corona or dielectric barrier discharges. These conditions make the experimental evidence presented in this work valuable for the advancement of modeling and the theoretical understanding of the discharge in bubbles in water.

Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations.

PubMed

Karthick, N K; Kumbharkhane, A C; Joshi, Y S; Mahendraprabu, A; Shanmugam, R; Elangovan, A; Arivazhagan, G

2017-05-05

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13 C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) CH⋯OC (EA), (EA) methylene CH⋯π electrons (CBZ) and (EA) methyl CH⋯Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (ε E ) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations

NASA Astrophysics Data System (ADS)

Karthick, N. K.; Kumbharkhane, A. C.; Joshi, Y. S.; Mahendraprabu, A.; Shanmugam, R.; Elangovan, A.; Arivazhagan, G.

2017-05-01

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) Csbnd H ⋯ Odbnd C (EA), (EA) methylene Csbnd H ⋯ π electrons (CBZ) and (EA) methyl Csbnd H ⋯ Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (εE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

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

NASA Astrophysics Data System (ADS)

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

1999-10-01

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.

Spectroscopic thermoacoustic imaging of water and fat composition

NASA Astrophysics Data System (ADS)

Bauer, Daniel R.; Wang, Xiong; Vollin, Jeff; Xin, Hao; Witte, Russell S.

2012-07-01

During clinical studies, thermoacoustic imaging (TAI) failed to reliably identify malignant breast tissue. To increase detection capability, we propose spectroscopic TAI to differentiate samples based on the slope of their dielectric absorption. Phantoms composed of different ratios of water and fat were imaged using excitation frequencies between 2.7 and 3.1 GHz. The frequency-dependent slope of the TA signal was highly correlated with that of its absorption coefficient (R2 = 0.98 and p < 0.01), indicating spectroscopic TAI can distinguish materials based on their intrinsic dielectric properties. This approach potentially enhances cancer detection due to the increased water content of many tumors.

Spectroscopic Factors from the Single Neutron Transfer Reaction 111Cd(d,p)112Cd

NASA Astrophysics Data System (ADS)

Jamieson, D. S.; Garrett, P. E.; Demand, G. A.; Finlay, P.; Green, K. L.; Leach, K. G.; Phillips, A. A.; Svensson, C. E.; Sumithrarachchi, C. S.; Triambak, S.; Wong, J.; Ball, G.; Faestermann, T.; Krücken, R.; Hertenberger, R.; Wirth, H.-F.

2013-03-01

The cadmium isotopes have been cited as excellent examples of vibrational nuclei for decades, with multi-phonon quadrupole, quadrupole-octupole, and mixed-symmetry states proposed. From a variety of experimental studies, a large amount of spectroscopic data has been obtained, recently focused on γ-ray studies. In the present work, the single-particle structure of 112Cd has been investigated using the 111Cd(ěcd, p)112Cd reaction. The investigation was carried out using a 22 MeV beam of polarized deuterons obtained from the Maier-Leibnitz Laboratory at Garching, Germany. The reaction ejectiles were momentum analyzed using a Q3D spectrograph, and 115 levels have been identified up to 4.2 MeV of excitation energy. Spin-parity has been assigned to each analyzed level, and angular distributions for the reaction cross sections and analyzing powers were obtained. Many additional levels have been observed compared with the previous (d,p) study performed with 8 MeV deuterons,1 including strongly populated 5- and 6- states. The former was previously assigned as a member of the quadrupole-octupole quintuplet, based on a strongly enhanced B(E2) value to the 3- state, but is now re-assigned as being predominately s1/2 ⊗ h11/2 configuration.

Spectroscopic properties of some borate glasses containg uranium

NASA Astrophysics Data System (ADS)

Culea, E.; Milea, I.; Bratu, I.

1993-03-01

Spectroscopic properties of some borate glasses containing 1-5%UO 3 have been studied in the fields of 700-1200 cm -1 and 10,000-30,000 cm -1 Absorption bands specific for U 6+ and U 4+ ions were observed. The increase of the melting time produces the reduction of U 6+ ions to U 4+.

Phenomenological and Spectroscopic Analysis on the Effects of Sediment Ageing and Organic Carbon on the Fate of a PCB Congener Spiked to Sediment

EPA Science Inventory

This study assesses the full cycle transport and fate of a polychlorinated biphenyl (PCB) congener spiked to sediment to empirically and spectroscopically investigate the effects of sediment ageing and organic carbon on the adsorption, desorption, and reaction of the PCB. Caesar ...

Raman Spectroscopic Detection of Graphitic Carbon of Biogenic Parentage in an Ancient South African Chert

NASA Technical Reports Server (NTRS)

Wang, Alian; Haskin, Larry A.; Kuebler, Karla E.; Jolliff, Bradley L.; Walsh, Maud M.

2001-01-01

The detection of reduced carbon in martian rocks and soils is important in the search for evidence of life. A Raman spectroscopic study of South Africa chert reveals that 50 ppm carbon or less can be determined by this technique. Additional information is contained in the original extended abstract.

Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

NASA Astrophysics Data System (ADS)

Kamnev, A. A.; Antonyuk, L. P.; Tugarova, A. V.; Tarantilis, P. A.; Polissiou, M. G.; Gardiner, P. H. E.

2002-06-01

Structural and compositional features of whole cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 under standard and heavy metal-stressed conditions are analysed using Fourier transform infrared (FTIR) spectroscopy and compared with the FT-Raman spectroscopic data obtained previously [J. Mol. Struct. 563-564 (2001) 199]. The structural spectroscopic information is considered together with inductively coupled plasma-mass spectrometric (ICP-MS) analytical data on the content of the heavy metal cations (Co2+, Cu2+ and Zn2+) in the bacterial cells. As a bacterial response to heavy metal stress, all the three metals, being taken up by bacterial cells from the culture medium (0.2 mM) in significant amounts (ca. 0.12, 0.48 and 4.2 mg per gram of dry biomass for Co, Cu and Zn, respectively), are shown to induce essential metabolic changes in the bacterium revealed in the spectra, including the accumulation of polyester compounds in bacterial cells and their enhanced hydration affecting certain IR vibrational modes of functional groups involved.

Distorted tetrahedral nickel-nitrosyl complexes: spectroscopic characterization and electronic structure.

PubMed

Soma, Shoko; Van Stappen, Casey; Kiss, Mercedesz; Szilagyi, Robert K; Lehnert, Nicolai; Fujisawa, Kiyoshi

2016-09-01

The linear nickel-nitrosyl complex [Ni(NO)(L3)] supported by a highly hindered tridentate nitrogen-based ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3), was prepared by the reaction of the potassium salt of the ligand with the nickel-nitrosyl precursor [Ni(NO)(Br)(PPh 3 ) 2 ]. The obtained nitrosyl complexes as well as the corresponding chlorido complexes [Ni(NO)(Cl)(PPh 3 ) 2 ] and [Ni(Cl)(L3)] were characterized by X-ray crystallography and different spectroscopic methods including IR/far-IR, UV-Vis, NMR, and multi-edge X-ray absorption spectroscopy at the Ni K-, Ni L-, Cl K-, and P K-edges. For comparative electronic structure analysis we also performed DFT calculations to further elucidate the electronic structure of [Ni(NO)(L3)]. These results provide the nickel oxidation state and the character of the Ni-NO bond. The complex [Ni(NO)(L3)] is best described as [Ni (II) (NO (-) )(L3)], and the spectroscopic results indicate that the phosphane complexes have a similar [Ni (II) (NO (-) )(X)(PPh 3 ) 2 ] ground state.

Anomaly detection for machine learning redshifts applied to SDSS galaxies

NASA Astrophysics Data System (ADS)

Hoyle, Ben; Rau, Markus Michael; Paech, Kerstin; Bonnett, Christopher; Seitz, Stella; Weller, Jochen

2015-10-01

We present an analysis of anomaly detection for machine learning redshift estimation. Anomaly detection allows the removal of poor training examples, which can adversely influence redshift estimates. Anomalous training examples may be photometric galaxies with incorrect spectroscopic redshifts, or galaxies with one or more poorly measured photometric quantity. We select 2.5 million `clean' SDSS DR12 galaxies with reliable spectroscopic redshifts, and 6730 `anomalous' galaxies with spectroscopic redshift measurements which are flagged as unreliable. We contaminate the clean base galaxy sample with galaxies with unreliable redshifts and attempt to recover the contaminating galaxies using the Elliptical Envelope technique. We then train four machine learning architectures for redshift analysis on both the contaminated sample and on the preprocessed `anomaly-removed' sample and measure redshift statistics on a clean validation sample generated without any preprocessing. We find an improvement on all measured statistics of up to 80 per cent when training on the anomaly removed sample as compared with training on the contaminated sample for each of the machine learning routines explored. We further describe a method to estimate the contamination fraction of a base data sample.

Structure, spectroscopy and dynamics of layered H2O and CO2 ices

USGS Publications Warehouse

,; Plattner, Nuria; Meuwly, Markus

2012-01-01

Molecular dynamics simulations of structural, spectroscopic and dynamical properties of mixed water–carbon dioxide (H2O–CO2) ices are discussed over temperature ranges relevant to atmospheric and astrophysical conditions. The simulations employ multipolar force fields to represent electrostatic interactions which are essential for spectroscopic and dynamical investigations. It is found that at the water/CO2 interface the water surface acts as a template for the CO2 component. The rotational reorientation times in both bulk phases agree well with experimental observations. A pronounced temperature effect on the CO2 reorientation time is observed between 100 K and 200 K. At the interface, water reorientation times are nearly twice as long compared to water in the bulk. The spectroscopy of such ices is rich in the far-infrared region of the spectrum and can be related to translational and rotational modes. Furthermore, spectroscopic signatures mediated across the water/CO2 interface are found in this frequency range (around 440 cm−1). These results will be particularly important for new airborne experiments such as planned for SOFIA.

Supernova Cosmology Inference with Probabilistic Photometric Redshifts (SCIPPR)

NASA Astrophysics Data System (ADS)

Peters, Christina; Malz, Alex; Hlozek, Renée

2018-01-01

The Bayesian Estimation Applied to Multiple Species (BEAMS) framework employs probabilistic supernova type classifications to do photometric SN cosmology. This work extends BEAMS to replace high-confidence spectroscopic redshifts with photometric redshift probability density functions, a capability that will be essential in the era the Large Synoptic Survey Telescope and other next-generation photometric surveys where it will not be possible to perform spectroscopic follow up on every SN. We present the Supernova Cosmology Inference with Probabilistic Photometric Redshifts (SCIPPR) Bayesian hierarchical model for constraining the cosmological parameters from photometric lightcurves and host galaxy photometry, which includes selection effects and is extensible to uncertainty in the redshift-dependent supernova type proportions. We create a pair of realistic mock catalogs of joint posteriors over supernova type, redshift, and distance modulus informed by photometric supernova lightcurves and over redshift from simulated host galaxy photometry. We perform inference under our model to obtain a joint posterior probability distribution over the cosmological parameters and compare our results with other methods, namely: a spectroscopic subset, a subset of high probability photometrically classified supernovae, and reducing the photometric redshift probability to a single measurement and error bar.

Density‐weighted concentric circle trajectories for high resolution brain magnetic resonance spectroscopic imaging at 7T

PubMed Central

Hingerl, Lukas; Moser, Philipp; Považan, Michal; Hangel, Gilbert; Heckova, Eva; Gruber, Stephan; Trattnig, Siegfried; Strasser, Bernhard

2017-01-01

Purpose Full‐slice magnetic resonance spectroscopic imaging at ≥7 T is especially vulnerable to lipid contaminations arising from regions close to the skull. This contamination can be mitigated by improving the point spread function via higher spatial resolution sampling and k‐space filtering, but this prolongs scan times and reduces the signal‐to‐noise ratio (SNR) efficiency. Currently applied parallel imaging methods accelerate magnetic resonance spectroscopic imaging scans at 7T, but increase lipid artifacts and lower SNR‐efficiency further. In this study, we propose an SNR‐efficient spatial‐spectral sampling scheme using concentric circle echo planar trajectories (CONCEPT), which was adapted to intrinsically acquire a Hamming‐weighted k‐space, thus termed density‐weighted‐CONCEPT. This minimizes voxel bleeding, while preserving an optimal SNR. Theory and Methods Trajectories were theoretically derived and verified in phantoms as well as in the human brain via measurements of five volunteers (single‐slice, field‐of‐view 220 × 220 mm2, matrix 64 × 64, scan time 6 min) with free induction decay magnetic resonance spectroscopic imaging. Density‐weighted‐CONCEPT was compared to (a) the originally proposed CONCEPT with equidistant circles (here termed e‐CONCEPT), (b) elliptical phase‐encoding, and (c) 5‐fold Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration accelerated elliptical phase‐encoding. Results By intrinsically sampling a Hamming‐weighted k‐space, density‐weighted‐CONCEPT removed Gibbs‐ringing artifacts and had in vivo +9.5%, +24.4%, and +39.7% higher SNR than e‐CONCEPT, elliptical phase‐encoding, and the Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration accelerated elliptical phase‐encoding (all P < 0.05), respectively, which lead to improved metabolic maps. Conclusion Density‐weighted‐CONCEPT provides clinically attractive full‐slice high‐resolution magnetic resonance spectroscopic imaging with optimal SNR at 7T. Magn Reson Med 79:2874–2885, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:29106742

Absorption and Luminescence Studies of Some Highly Fluorescent Derivatives of Vitamin B1; Solvent and pH Effects

NASA Astrophysics Data System (ADS)

Marciniak, B.; Koput, J.; Kozubek, H.

1990-08-01

The influence of solvent on the UV-visible absorption and luminescence spectra of some highly fluorescent vitamin B1 derivatives, the products of the reaction of N-methylated vitamin B1 with cytidine (I), adenosine (II) and 2-amino-4-methylpyridine (III) is studied. Spectroscopic manifestations of protonation of I and II are also investigated using a semiempirical INDO/S CI method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with the experimental spectra. Calculated charge densities on heteroatoms in the ground and excited singlet and triplet states are correlated with changes of the experimental pKa values with excitation. The results for I and II are compared with those for the trimethylated pyrichrominium ion (III) previously studied

Crystallographic and Spectroscopic Symmetry Notations.

ERIC Educational Resources Information Center

Sharma, B. D.

1982-01-01

Compares Schoenflies and Hermann-Mauguin notations of symmetry. Although the former (used by spectroscopists) and latter (used by crystallographers) both describe the same symmetry, there are distinct differences in the manner of description which may lead to confusion in correlating the two notations. (Author/JN)

Neurologic 3D MR Spectroscopic Imaging with Low-Power Adiabatic Pulses and Fast Spiral Acquisition

PubMed Central

Gagoski, Borjan A.; Sorensen, A. Gregory

2012-01-01

Purpose: To improve clinical three-dimensional (3D) MR spectroscopic imaging with more accurate localization and faster acquisition schemes. Materials and Methods: Institutional review board approval and patient informed consent were obtained. Data were acquired with a 3-T MR imager and a 32-channel head coil in phantoms, five healthy volunteers, and five patients with glioblastoma. Excitation was performed with localized adiabatic spin-echo refocusing (LASER) by using adiabatic gradient-offset independent adiabaticity wideband uniform rate and smooth truncation (GOIA-W[16,4]) pulses with 3.5-msec duration, 20-kHz bandwidth, 0.81-kHz amplitude, and 45-msec echo time. Interleaved constant-density spirals simultaneously encoded one frequency and two spatial dimensions. Conventional phase encoding (PE) (1-cm3 voxels) was performed after LASER excitation and was the reference standard. Spectra acquired with spiral encoding at similar and higher spatial resolution and with shorter imaging time were compared with those acquired with PE. Metabolite levels were fitted with software, and Bland-Altman analysis was performed. Results: Clinical 3D MR spectroscopic images were acquired four times faster with spiral protocols than with the elliptical PE protocol at low spatial resolution (1 cm3). Higher-spatial-resolution images (0.39 cm3) were acquired twice as fast with spiral protocols compared with the low-spatial-resolution elliptical PE protocol. A minimum signal-to-noise ratio (SNR) of 5 was obtained with spiral protocols under these conditions and was considered clinically adequate to reliably distinguish metabolites from noise. The apparent SNR loss was not linear with decreasing voxel sizes because of longer local T2* times. Improvement of spectral line width from 4.8 Hz to 3.5 Hz was observed at high spatial resolution. The Bland-Altman agreement between spiral and PE data is characterized by narrow 95% confidence intervals for their differences (0.12, 0.18 of their means). GOIA-W(16,4) pulses minimize chemical-shift displacement error to 2.1%, reduce nonuniformity of excitation to 5%, and eliminate the need for outer volume suppression. Conclusion: The proposed adiabatic spiral 3D MR spectroscopic imaging sequence can be performed in a standard clinical MR environment. Improvements in image quality and imaging time could enable more routine acquisition of spectroscopic data than is possible with current pulse sequences. © RSNA, 2011 PMID:22187628

Synthesis, spectroscopic characterization and structural investigations of a new charge transfer complex of 2,6-diaminopyridine with 3,5-dinitrobenzoic acid: DNA binding and antimicrobial studies

NASA Astrophysics Data System (ADS)

Khan, Ishaat M.; Ahmad, Afaq; Kumar, Sarvendra

2013-03-01

A new charge transfer (CT) complex [(DAPH)+(DNB)-] consisting of 2,6-diaminopyridine (DAP) as donor and 3,5-dinitrobenzoic acid (DNB-H) as acceptor, was synthesized and characterized by FTIR, 1H and 13C NMR, ESI mass spectroscopic and X-ray crystallographic techniques. The hydrogen bonding (N+-H⋯O-) plays an important role to consolidate the cation and anion together. CT complex shows a considerable interaction with Calf thymus DNA. The CT complex was also tested for its antibacterial activity against two Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis and two Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa strains by using Tetracycline as standard, and antifungal property against Aspergillus niger, Candida albicans, and Penicillium sp. by using Nystatin as standard. The results were compared with standard drugs and significant conclusions were obtained. A polymeric net work through H-bonding interactions between neighboring moieties was observed. This has been attributed to the formation of 1:1 type CT complex.

Analysis of structural transformation in wool fiber resulting from oxygen plasma treatment using vibrational spectroscopy

NASA Astrophysics Data System (ADS)

Barani, Hossein; Haji, Aminoddin

2015-01-01

The aim of this study was to investigate the influence of oxygen plasma procedure at different time treatments on wool fiber using the micro-Raman spectroscopy as a non-destructive vibrational spectroscopic technique and Fourier transform infrared spectroscopy. The amide I and III regions, Csbnd C skeletal vibration region, and Ssbnd S and Csbnd S bonds vibration regions were analyzed with the Raman microscope. The Fourier transform infrared spectroscope analysis was employed to find out the effect of oxygen plasma treatment on the cysteic acid residues content of the wool fiber sample. The results indicated that the α-helix structure was the highest component content of wool fiber. Moreover, the protein secondary structure of wool fibers was transformed from α-helical arrangement to the β-pleated sheet configuration during the oxygen plasma treatment. Also, the disulphide bonds content in the treated wool fiber reduced because they were fractured and oxidized during oxygen plasma treatment. The oxygen plasma treated samples presented higher cysteic acid compared to the untreated wool samples due to produce more cleavage of disulfide linkages.

A spectroscopic approach to monitor the cut processing in pulsed laser osteotomy.

PubMed

Henn, Konrad; Gubaidullin, Gail G; Bongartz, Jens; Wahrburg, Jürgen; Roth, Hubert; Kunkel, Martin

2013-01-01

During laser osteotomy surgery, plasma arises at the place of ablation. It was the aim of this study to explore whether a spectroscopic analysis of this plasma would allow identification of the type of tissue that was affected by the laser. In an experimental setup (Rofin SCx10, CO(2) Slab Laser, wavelength 10.6 μm, pulse duration 80 μs, pulse repetition rate 200 Hz, max. output in cw-mode 100 W), the plasma spectra evoked by a pulsed laser, cutting 1-day postmortem pig and cow bones, were recorded. Spectra were compared to the reference spectrum of bone via correlation analysis. Our measurements show a clear differentiation between the plasma spectra when cutting either a bone or a soft tissue. The spectral changes could be detected from one to the next spectrum within 200 ms. Continuous surveillance of plasma spectra allows us to differentiate whether bone or soft tissue is hit by the last laser pulse. With this information, it may be possible to stop the laser when cutting undesired soft tissue and to design an automatic control of the ablation process.

Spectroscopic Evidence of the Improvement of Reactive Iron Mineral Content in Red Soil by Long-Term Application of Swine Manure

PubMed Central

Huang, Chichao; Liu, Sha; Li, Ruizhi; Sun, Fusheng; Zhou, Ying; Yu, Guanghui

2016-01-01

Mineral elements in soil solutions are thought to be the precursor of the formation of reactive minerals, which play an important role in global carbon (C) cycling. However, information regarding the regulation of mineral elements release in soil is scarce. Here, we examined the long-term (i.e., 23 yrs) effects of fertilisation practices on Fe minerals in a red soil in Southern China. The results from chemical analysis and Fourier-transform infrared spectroscopy showed that long-term swine manure (M) treatment released greater amounts of minerals into soil solutions than chemical fertilisers (NPK) treatment, and Fe played a dominant role in the preservation of dissolved organic C. Furthermore, Fe K-edge X-ray absorption near-edge fine structure spectroscopy demonstrated that reactive Fe minerals were mainly composed of less crystalline ferrihydrite in the M-treated soil and more crystalline goethite in the NPK-treated soil. In conclusion, this study reported spectroscopic evidence of the improvement of reactive Femineral content in the M-treated soil colloids when compared to NPK-treated soil colloids. PMID:26752419

Absolute parameters of eclipsing binaries in Southern Hemisphere sky - II: QY Tel

NASA Astrophysics Data System (ADS)

Erdem, A.; Sürgit, D.; Engelbrecht, C. A.; van Heerden, H. P.; Manick, R.

2016-11-01

This paper presents the first analysis of spectroscopic and photometric observations of the neglected southern eclipsing binary star, QY Tel. Spectroscopic observations were carried out at the South African Astronomical Observatory in 2013. New radial velocity curves from this study and V light curves from the All Sky Automated Survey were solved simultaneously using modern light and radial velocity curve synthesis methods. The final model describes QY Tel as a detached binary star where both component stars fill at least half of their Roche limiting lobes. The masses and radii were found to be 1.32 (± 0.06) M⊙, 1.74 (± 0.15) R⊙ and 1.44 (± 0.09) M⊙, 2.70 (± 0.16) R⊙ for the primary and secondary components of the system, respectively. The distance to QY Tel was calculated as 365 (± 40) pc, taking into account interstellar extinction. The evolution case of QY Tel is also examined. Both components of the system are evolved main-sequence stars with an age of approximately 3.2 Gy, when compared to Geneva theoretical evolution models.

Crystal structure characterization as well as theoretical study of spectroscopic properties of novel Schiff bases containing pyrazole group.

PubMed

Guo, Jia; Ren, Tiegang; Zhang, Jinglai; Li, Guihui; Li, Weijie; Yang, Lirong

2012-09-01

A series of novel Schiff bases containing pyrazole group were synthesized using 1-aryl-3-methyl-4-benzoyl-5-pyrazolone and phenylenediamine as the starting materials. All as-synthesized Schiff bases were characterized by means of NMR, FT-IR, and MS; and the molecular geometries of two Schiff bases as typical examples were determined by means of single crystal X-ray diffraction. In the meantime, the ultraviolet-visible light absorption spectra and fluorescent spectra of various as-synthesized products were also measured. Moreover, the B3LYP/6-1G(d,p) method was used for the optimization of the ground state geometry of the Schiff bases; and the spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVTZ basis set of TD-B3LYP method. It has been found that all as-synthesized Schiff bases show a remarkable absorption peak in a wavelength range of 270-370 nm; and their maximum emission peaks are around 344 nm and 332 nm, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

The Spectroscopic Ages of Passive Galaxies in a z=1.62 Protocluster

NASA Astrophysics Data System (ADS)

Lee-Brown, Donald

2017-07-01

IRC 0218 is a protocluster at z = 1.62 with a wealth of observations that make it an ideal target for resolving the interplay between galaxy properties and environment at high redshift. We have used extremely deep HST spectroscopic data to derive unambiguous membership and stellar ages via the 4000 angstrom break for 14 members with stellar masses log(M) > 10.2. We find that at high stellar masses, log(M) > 10.85, the fraction of quiescent galaxies in the cluster is 2× higher than the field value. At lower stellar masses, the protocluster and field have consistent quiescent fractions. Despite this mass trend, we see no comparable relation between galaxy stellar age and mass for the quiescent members. Taken together, these results may reflect the impact of dry mergers on the protocluster galaxies. Alternately, the results may imply that the mass trend we observe in the IRC 0218 quiescent fraction was imprinted over a short timescale. This talk will place our results in the context of studies of other high redshift clusters and likely descendent environments at z = 1.

Profiling of red pigment produced by Streptomyces sp. JAR6 and its bioactivity.

PubMed

Abraham, Jayanthi; Chauhan, Ritika

2018-01-01

Actinomycetes strain was isolated from leaf litter soil sample and was identified as Streptomyces sp. by conventional and molecular approaches. The biologically active compound responsible for antimicrobial and anticancer activity of the strain JAR6 was elucidated by solid state fermentation followed by subsequent chromatographic and spectroscopic analysis. Extraction, purification and structural confirmation of red pigment metabolite viz undecylprodigiosin were established on the basis of spectroscopic studies and comparing the data from the literature. The biologically active compound was tested against Gram-positive and Gram-negative clinical isolates and its minimum inhibitory concentration was recorded. The antimicrobial activity of undecylprodigiosin is more prominent against Salmonella sp., Proteus mirabilis , Shigella sp. and Enterococcus sp. whereas, it was less effective against Staphylococcus aureus , Klebsiella pneumonia and Escherichia coli . The anticancer activity of undecylprodigiosin was tested against HeLa cell lines and it exhibited commendable cytotoxicity effect with IC 50 value of 145 µg/ml. The present investigation reveals that undecylprodigiosin produced by Streptomyces strain JAR6 is a potent bioactive metabolite with effective pharmaceutical properties.

Spectroscopic and energy transfer studies of Er3+ ions in B2O3-TeO2-MgO-ZnO glasses

NASA Astrophysics Data System (ADS)

Vijayakumar, M.; Arunkumar, S.; Maheshvaran, K.; Marimuthu, K.

2016-05-01

Composition dependent spectroscopic behavior of Er3+ doped telluroborate glasses were prepared and the energy transfer mechanism in Er3+ ions were investigated for 1.532 µm amplification. The emission cross-section and gain coefficient for 4I13/2→4I15/2 level of Er3+ ions have been analysed through the Judd-Ofelt and McCumber theory. The excited state decay curves were measured and the effect of TeO2 on the lifetime for 4I13/2→4I15/2 level of Er3+ ions has been associated with the various energy transfer mechanism. Further the interaction between Er3+ and OH- were investigated and it was confirmed that the OH free radicals in the prepared glasses are dominant quenching center through the non-radiative relaxation that causes the quenching of 1.532 µm amplification. The non-radiative rate through the OH content were calculated and compared with the reported Er3+ doped glasses.

Time-resolved optical emission spectroscopic studies of picosecond laser produced Cr plasma

NASA Astrophysics Data System (ADS)

Rao, Kavya H.; Smijesh, N.; Klemke, N.; Philip, R.; Litvinyuk, I. V.; Sang, R. T.

2018-06-01

Time-resolved optical emission spectroscopic measurements of a plasma generated by irradiating a Cr target using 60 picosecond (ps) and 300 ps laser pulses are carried out to investigate the variation in the line width (δλ) of emission from neutrals and ions for increasing ambient pressures. Measurements ranging from 10-6 Torr to 102 Torr show a distinctly different variation in the δλ of neutrals (Cr I) compared to that of singly ionized Cr (Cr II), for both irradiations. δλ increases monotonously with pressure for Cr II, but an oscillation is evident at intermediate pressures for Cr I. This oscillation does not depend on the laser pulse widths used. In spite of the differences in the plasma formation mechanisms, it is experimentally found that there is an optimum intermediate background pressure for which δλ of neutrals drops to a minimum. Importantly, these results underline the fact that for intermediate pressures, the usual practice of calculating the plasma number density from the δλ of neutrals needs to be judiciously done, to avoid reaching inaccurate conclusions.

Parent Stars of Extrasolar Planets. VII. New Abundance Analyses of 30 Systems

NASA Astrophysics Data System (ADS)

Laws, Chris; Gonzalez, Guillermo; Walker, Kyle M.; Tyagi, Sudhi; Dodsworth, Jeremey; Snider, Keely; Suntzeff, Nicholas B.

2003-05-01

The results of new spectroscopic analyses of 30 stars with giant planet and/or brown dwarf companions are presented. Values for Teff and [Fe/H] are used in conjunction with Hipparcos data and Padua isochrones to derive masses, ages, and theoretical surface gravities. These new data are combined with spectroscopic and photometric metallicity estimates of other stars harboring planets and published samples of F, G, and K dwarfs to compare several subsets of planet bearing stars with similarly well-constrained control groups. The distribution of [Fe/H] values continues the trend uncovered in previous studies in that stars hosting planetary companions have a higher mean value than otherwise similar nearby stars. We also investigate the relationship between stellar mass and the presence of giant planets, and we find statistically marginal but suggestive evidence of a decrease in the incidence of radial velocity companions orbiting relatively less massive stars. If confirmed with larger samples, this would represent a critical constraint to both planetary formation models, as well as to estimates of the distribution of planetary systems in our Galaxy.

Nortriterpenoids from the Fruiting Bodies of the Mushroom Ganoderma resinaceum.

PubMed

Chen, Xian-Qiang; Chen, Ling-Xiao; Zhao, Jing; Tang, Yu-Ping; Li, Shao-Ping

2017-06-28

Ganoderma resinaceum is usually used as ethnomedicine for immune-regulation, hyperglycemia, and liver disease. To date, only a few chemical constituents have been reported from G . resinaceum . In this study, fifteen nortriterpenoids including six new nortriterpenoids ( 1 - 6 ) and nine known analogs ( 7 - 15 ), were separated and purified from the fruiting bodies of G . resinaceum . New compounds were identified as lucidone I ( 1 ), lucidone J ( 2 ), lucidone K ( 3 ), lucidone I ( 4 ), ganosineniol B ( 5 ), and ganosineniol C ( 6 ), based on analysis of extensive spectroscopic data (high resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), infrared (IR), and ultraviolet (UV)). The known compounds were assigned as lucidone A ( 7 ), lucidone B ( 8 ), lucidone H ( 9 ), lucidone E ( 10 ), lucidone F ( 11 ), lucidone D ( 12 ), lucidone C ( 13 ), ganoderense F ( 14 ), and ganosineniol A ( 15 ), by comparing their spectroscopic data with those reported in the literature. Compounds 3 , 4 , and 7 - 13 were examined for α -glucosidase inhibitory activity and display no significant activity, but the finding may support that the side chain of ganoderma triterpenoids played an important role in α -glucosidase inhibitory activity.

Spectroscopic follow-up of the Hercules-Aquila Cloud

NASA Astrophysics Data System (ADS)

Simion, Iulia T.; Belokurov, Vasily; Koposov, Sergey E.; Sheffield, Allyson; Johnston, Kathryn V.

2018-05-01

We designed a follow-up program to find the spectroscopic properties of the Hercules-Aquila Cloud (HAC) and test scenarios for its formation. We measured the radial velocities (RVs) of 45 RR Lyrae in the southern portion of the HAC using the facilities at the MDM observatory, producing the first large sample of velocities in the HAC. We found a double-peaked distribution in RVs, skewed slightly to negative velocities. We compared both the morphology of HAC projected on to the plane of the sky and the distribution of velocities in this structure outlined by RR Lyrae and other tracer populations at different distances to N-body simulations. We found that the behaviour is characteristic of an old, well-mixed accretion event with small apo-galactic radius. We cannot yet rule out other formation mechanisms for the HAC. However, if our interpretation is correct, HAC represents just a small portion of a much larger debris structure spread throughout the inner Galaxy whose distinct kinematic structure should be apparent in RV studies along many lines of sight.

Development and Validation of Stability Indicating Spectroscopic Method for Content Analysis of Ceftriaxone Sodium in Pharmaceuticals

PubMed Central

Ethiraj, Revathi; Thiruvengadam, Ethiraj; Sampath, Venkattapuram Saravanan; Vahid, Abdul; Raj, Jithin

2014-01-01

A simple, selective, and stability indicating spectroscopic method has been selected and validated for the assay of ceftriaxone sodium in the powder for injection dosage forms. Proposed method is based on the measurement of absorbance of ceftriaxone sodium in aqueous medium at 241 nm. The method obeys Beer's law in the range of 5–50 μg/mL with correlation coefficient of 0.9983. Apparent molar absorptivity and Sandell's sensitivity were found to be 2.046 × 103 L mol−1 cm−1 and 0.02732 μg/cm2/0.001 absorbance units. This study indicated that ceftriaxone sodium was degraded in acid medium and also underwent oxidative degradation. Percent relative standard deviation associated with all the validation parameters was less than 2, showing compliance with acceptance criteria of Q2 (R1), International Conference on Harmonization (2005) guidelines. Then the proposed method was successfully applied to the determination of ceftriaxone sodium in sterile preparation and results were comparable with reported methods. PMID:27355020

Photoacoustic FTIR spectroscopic study of undisturbed human cortical bone

NASA Astrophysics Data System (ADS)

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

2013-02-01

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

Detection of spectroscopic binaries in the Gaia-ESO Survey

NASA Astrophysics Data System (ADS)

Van der Swaelmen, M.; Merle, T.; Van Eck, S.; Jorissen, A.

2017-12-01

The Gaia-ESO survey (GES) is a ground-based spectroscopic survey, complementing the Gaia mission, in order to obtain high accuracy radial velocities and chemical abundances for 10^5 stars. Thanks to the numerous spectra collected by the GES, the detection of spectroscopic multiple system candidates (SBn, n ≥ 2) is one of the science case that can be tackled. We developed at IAA (Institut d'Astronomie et d'Astrophysique) a novative automatic method to detect multiple components from the cross-correlation function (CCF) of spectra and applied it to the CCFs provided by the GES. Since the bulk of the Milky Way field targets has been observed in both HR10 and HR21 GIRAFFE settings, we are also able to compare the efficiency of our SB detection tool depending on the wavelength range. In particular, we show that HR21 leads to a less efficient detection compared to HR10. The presence of strong and/or saturated lines (Ca II triplet, Mg I line, Paschen lines) in the wavelength domain covered by HR21 hampers the computation of CCFs, which tend to be broadened compared to their HR10 counterpart. The main drawback is that the minimal detectable radial velocity difference is ˜ \\SI{60}km/s for HR21 while it is ˜ \\SI{25}km/s for HR10. A careful design of CCF masks (especially masking Ca triplet lines) can substantially improve the detectability rate of HR21. Since HR21 spectra are quite similar to the one produced by the RVS spectrograph of the Gaia mission, analysis of RVS spectra in the context of spectroscpic binaries can take adavantage of the lessons learned from the GES to maximize the detection rate.

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

NASA Astrophysics Data System (ADS)

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

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

IR Spectroscopic signs of malignant neoplasms in the thyroid gland

NASA Astrophysics Data System (ADS)

Tolstorozhev, G. B.; Skornyakov, I. V.; Butra, V. A.

2012-03-01

We use Fourier transform IR spectroscopy to study thyroid tumor tissues which were removed during surgery. The IR spectra of the tissues with pathological foci are compared with data from histologic examination. In the region of N-H, C-H, and C = O stretching vibrations, the IR spectra of the tissues for thyroid cancer are different from the IR spectra of tissues without malignant formations. We identify the spectral signs of thyroid cancer. We show that IR analysis is promising for identification of thyroid pathology at the molecular level.

Ag-ZnO nanostructure for ANTA explosive molecule detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaik, Ummar Pasha; Sangani, L. D. Varma; Gaur, Anshu

2016-05-23

Ag/ZnO nanostructure for surface enhanced Raman scattering application in the detection of ANTA explosive molecule is demonstrated. A highly rough ZnO microstructure was achieved by rapid thermal annealing of metallic Zn film. Different thickness Ag nanostructures are decorated over these ZnO microstructures by ion beam sputtering technique. Surface enhanced Raman spectroscopic studies carried out over Ag/ZnO substrates have shown three orders higher enhancement compared to bare Ag nanostructure deposited on the same substrate. The reasons behind such huge enhancement are discussed based on the morphology of the sample.

Structural and spectroscopic investigations on deuteron glasses belonging to the potassium dihydrogen phosphate family

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, Rajul Ranjan, E-mail: rajul@barc.gov.in; Chitra, R.; Abraham, Geogy J.

2015-06-24

X-ray powder diffraction and Raman measurements were performed on the mixed crystals of deuterated potassium dihydrogen phosphate (DKDP) and deuterated ammonium dihydrogen phosphate (DADP) grown at our lab. These crystals are known to behave like deuteron glasses due to frustration between ferroelectric and antiferroelectric ordering. Both spectral as well as structural studies indicate that crystals belonging to the glassy regions of the crystal composition have stronger O-D-O hydrogen bonds as compared to those belong to the ferroelectric or antiferroelectric regions of the crystal composition.

Principles of ESCA and applications to metal corrosion, coating and lubrication. [Electron Spectroscopy for Chemical Analysis

NASA Technical Reports Server (NTRS)

Wheeler, D. R.

1978-01-01

The principles of ESCA (electron spectroscopy for chemical analysis) are described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques are evaluated. The use of ESCA is illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. Finally, a bibliography of material that is useful for further study of ESCA is presented and commented upon.

Glutamate receptors as seen by light: Spectroscopic studies of structure-function relationships

PubMed Central

Mankiewicz, Kimberly A.; Jayaraman, Vasanthi

2010-01-01

Ionotropic glutamate receptors are major excitatory receptors in the central nervous system and also have far reaching influence in other areas of the body. Their modular nature has allowed for the isolation of the ligand binding domain and subsequent structural studies using a variety of spectroscopic techniques. This review will discuss the role of specific ligand:protein interactions in mediating activation in the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype of glutamate receptors as established by various spectroscopic investigations of the GluR2 and GluR4 subunits of this receptor. Specifically, this review will provide an introduction of the insight gained from X-ray crystallography and nuclear magnetic resonance (NMR) investigations and then go on to focus on studies utilizing vibrational spectroscopy and fluorescence resonance energy transfer (FRET) to study the behavior of the isolated ligand binding domain in solution and discuss the importance of specific ligand:protein interactions in the mechanism of receptor activation. PMID:17934637

Spectroscopic survey of southern hemisphere white dwarfs. II. Spectroscopic data for forty-one southern white dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wegner, G.

New spectroscopic data on 41 southern white dwarfs are presented. Most of these stars have not teen previously observed spectroscopically. Spectral types, as well as equivalent widths and line profiles for a few selected lines, are given. (auth)

Spectroscopic and DFT-based computational studies on the molecular electronic structural characteristics and the third-order nonlinear property of an organic NLO crystal: (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide

NASA Astrophysics Data System (ADS)

Sasikala, V.; Sajan, D.; Joseph, Lynnette; Balaji, J.; Prabu, S.; Srinivasan, P.

2017-04-01

Single crystals of (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide (CBMBSH) have been grown by slow evaporation crystal growth method. The structure stabilizing intramolecular donor-acceptor interactions and the presence of the Nsbnd H⋯O, Csbnd H⋯O and Csbnd H⋯C(π) hydrogen bonds in the crystal were confirmed by vibrational spectroscopic and DFT methods. The linear optical absorption characteristics of the solvent phase of CBMBSH were investigated using UV-Vis-NIR spectroscopic and TD-DFT approaches. The 2PA assisted RSA nonlinear absorption and the optical limiting properties of CBMBSH were studied using the open-aperture Z-scan method. The topological characteristics of the electron density have been determined using the quantum theory of atoms in molecules method.

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

PubMed Central

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

2014-01-01

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

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

DOE PAGES

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

2014-09-10

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

Raman spectroscopic signature of vaginal fluid and its potential application in forensic body fluid identification.

PubMed

Sikirzhytskaya, Aliaksandra; Sikirzhytski, Vitali; Lednev, Igor K

2012-03-10

Traces of human body fluids, such as blood, saliva, sweat, semen and vaginal fluid, play an increasingly important role in forensic investigations. However, a nondestructive, easy and rapid identification of body fluid traces at the scene of a crime has not yet been developed. The obstacles have recently been addressed in our studies, which demonstrated the considerable potential of Raman spectroscopy. In this study, we continued to build a full library of body fluid spectroscopic signatures. The problems concerning vaginal fluid stain identification were addressed using Raman spectroscopy coupled with advanced statistical analysis. Calculated characteristic Raman and fluorescent spectral components were used to build a multidimensional spectroscopic signature of vaginal fluid, which demonstrated good specificity and was able to handle heterogeneous samples from different donors. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Effect of the solvent environment on the spectroscopic properties and dynamics of the lowest excited states of carotenoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank, H.A.; Bautista, J.A.; Josue, J.

2000-05-11

The spectroscopic properties and dynamics of the lowest excited singlet states of peridinin, fucoxanthin, neoxanthin, uriolide acetate, spheroidene, and spheroidenone in several different solvents have been studied by steady-state absorption and fast-transient optical spectroscopic techniques. Peridinin, fucoxanthin, uriolide acetate, and spheroidenone, which contain carbonyl functional groups in conjugation with the carbon-carbon {pi}-electron system, display broader absorption spectral features and are affected more by the solvent environment than neoxanthin and spheroidene, which do not contain carbonyl functional groups. The possible sources of the spectral broadening are explored by examining the absorption spectra at 77 K in glassy solvents. Also, carotenoids whichmore » contain carbonyls have complex transient absorption spectra and show a pronounced dependence of the excited singlet state lifetime on the solvent environment. It is postulated that these effects are related to the presence of an intramolecular charge transfer state strongly coupled to the S{sub 1} (2{sup 1}A{sub g}) excited singlet state. Structural variations in the series of carotenoids studied here make it possible to focus on the general molecular features that control the spectroscopic and dynamic properties of carotenoids.« less

Recent advances in the applications of vibrational spectroscopic imaging and mapping to pharmaceutical formulations

NASA Astrophysics Data System (ADS)

Ewing, Andrew V.; Kazarian, Sergei G.

2018-05-01

Vibrational spectroscopic imaging and mapping approaches have continued in their development and applications for the analysis of pharmaceutical formulations. Obtaining spatially resolved chemical information about the distribution of different components within pharmaceutical formulations is integral for improving the understanding and quality of final drug products. This review aims to summarise some key advances of these technologies over recent years, primarily since 2010. An overview of FTIR, NIR, terahertz spectroscopic imaging and Raman mapping will be presented to give a perspective of the current state-of-the-art of these techniques for studying pharmaceutical samples. This will include their application to reveal spatial information of components that reveals molecular insight of polymorphic or structural changes, behaviour of formulations during dissolution experiments, uniformity of materials and detection of counterfeit products. Furthermore, new advancements will be presented that demonstrate the continuing novel applications of spectroscopic imaging and mapping, namely in FTIR spectroscopy, for studies of microfluidic devices. Whilst much of the recently developed work has been reported by academic groups, examples of the potential impacts of utilising these imaging and mapping technologies to support industrial applications have also been reviewed.

Spectroscopic and theoretical studies of charge-transfer interaction of 1-(2-pyridylazo)-2-napthol with nitroaromatics

NASA Astrophysics Data System (ADS)

Karmakar, Animesh; Singh, Bula

2017-05-01

1-(2-Pyridylazo)-2-napthol (hereafter 1Q) is widely used as a chelating ligand applied in chelatometric, spectrophotometric analysis of metal ions. It appeared from the literature survey that no inclusion complex of 1Q was reported with nitroaromatics. The formation of charge-transfer complex gives an opportunity to improve the physico-chemical properties of different donors. So the complex of 1Q with 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), picric acid (PA), and 3,5-dinitrosalicylic acid (3,5-DNSA) was described in this work in methanol medium. The ground and excited state binding constants and other spectroscopic data have been determined using UV-vis and fluorescence spectroscopic studies. All the complexes have been synthesized and characterized using FT-IR, 1H NMR, and elemental analysis. Spectroscopic data reveal that 1Q joins by a N+sbnd Hsbnd O- type hydrogen bond with nitroaromatics. Job's plot of the continuous variation of absorbance indicates that stoichiometry of CT-complex was 1:1. Thermal stability of the synthesized complex has determined by TGA-DTA analysis. Energy-minimization DFT calculation further supported the formation of the H-bonded charge-transfer adduct.

(31) P MR spectroscopic imaging combined with (1) H MR spectroscopic imaging in the human prostate using a double tuned endorectal coil at 7T.

PubMed

Luttje, Mariska P; Italiaander, Michel G M; Arteaga de Castro, Catalina S; van der Kemp, Wybe J M; Luijten, Peter R; van Vulpen, Marco; van der Heide, Uulke A; Klomp, Dennis W J

2014-12-01

Improved diagnostic sensitivity could be obtained in cancer detection and staging when individual compounds of the choline pool can be detected. Therefore, a novel coil design is proposed, providing the ability to acquire both (1) H and (31) P magnetic resonance spectroscopic imaging (MRSI) in patients with prostate cancer. A two-element (1) H/(31) P endorectal coil was designed by adjusting a commercially available 3T endorectal coil. The two-element coil setup was interfaced as a transceiver to a whole body 7T MR scanner. Simulations and phantom measurements were performed to compare the efficiency of the coil. (1) H MRSI and (31) P MRSI were acquired in vivo in prostate cancer patients. The efficiency of the (1) H/(31) P coil is comparable to the dual channel (1) H coil previously published. Individually distinguishable phospholipid metabolites in the in vivo (31) P spectra were: phosphoethanolamine, phosphocholine, phosphate, glycerophosphoethanolamine, glycerophosphocholine, phosphocreatine, and adenosine triposphate. (1) H MRSI was performed within the same scan session, visualizing choline, polyamines, creatine, and citrate. (1) H MRSI and (31) P MRSI can be acquired in the human prostate at 7T within the same scan session using an endorectal coil matched and tuned for (1) H (quadrature) and (31) P (linear) without the need of cable traps and with negligible efficiency losses in the (1) H and (31) P channel. © 2013 Wiley Periodicals, Inc.

Changes in NAA and lactate following ischemic stroke: a serial MR spectroscopic imaging study.

PubMed

Muñoz Maniega, S; Cvoro, V; Chappell, F M; Armitage, P A; Marshall, I; Bastin, M E; Wardlaw, J M

2008-12-09

Although much tissue damage may occur within the first few hours of ischemic stroke, the duration of tissue injury is not well defined. We assessed the temporal pattern of neuronal loss and ischemia after ischemic stroke using magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI). We measured N-acetylaspartate (NAA) and lactate in 51 patients with acute ischemic stroke at five time points, from admission to 3 months, in voxels classified as normal, possibly or definitely abnormal (ischemic) according to the appearance of the stroke lesion on the admission DWI. We compared changes in NAA and lactate in different voxel classes using linear mixed models. NAA was significantly reduced from admission in definitely and possibly abnormal (p < 0.01) compared to contralateral normal voxels, reaching a nadir by 2 weeks and remaining reduced at 3 months. Lactate was significantly increased in definitely and possibly abnormal voxels (p < 0.01) during the first 5 days, falling to normal at 2 weeks, rising again later in these voxels. The progressive fall in N-acetylaspartate suggests that some additional neuronal death may continue beyond the first few hours for up to 2 weeks or longer. The mechanism is unclear but, if correct, then it is possible that interventions to limit this ongoing subacute tissue damage might add to the benefit of hyperacute treatment, making further improvements in outcome possible.

Recent developments in spectroscopic imaging techniques for historical paintings - A review

NASA Astrophysics Data System (ADS)

Alfeld, M.; de Viguerie, L.

2017-10-01

This paper provides an overview over the application of scanning macro-XRF with mobile instruments for the investigation of historical paintings. The method is compared to synchrotron based macro-XRF imaging and Neutron Activation Auto-Radiography. Full-Field XRF imaging instruments, a potential future alternative to scanning macro-XRF, and confocal XRF, providing complementary depth profiles and developing into a 3D imaging technique itself, are described with the focus on investigations of historical paintings. Recent developments of X-ray radiography are presented and the investigation of cultural heritage objects other than paintings by MA-XRF is summarized. In parallel to XRF, hyperspectral imaging in the visible and range has developed into a technique with comparable capabilities, providing insight in chemical compounds, where XRF imaging identifies the distribution of elements. Due to the complementary nature of these techniques the latter is summarized. Further, progress and state of the art in data evaluation for spectroscopic imaging is discussed. In general it could be observed that technical capabilities in MA-XRF and hyperspectral imaging have reached a plateau and that with the availability of commercial instruments the focus of recent studies has shifted from the development of methods to applications of the instruments. Further, that while simple instruments are easily available with medium budgets only few groups have high-end instrumentation available, bought or in-house built.

Romano-British wall paintings: Raman spectroscopic analysis of fragments from two urban sites of early military colonisation.

PubMed

Edwards, H G M; Middleton, P S; Hargreaves, M D

2009-08-01

Raman spectroscopic analyses of 1st century AD Romano-British villa wall-painting fragments from two important military and early urban centres at Colchester and Lincoln have demonstrated some interesting contrasts in technique and palette usage. Colchester, the earliest fortified settlement, developed a sophisticated painting and craft industry compared with Lincoln in the assimilation of novel substrate preparation ideas and pigment adoption. The earliest use of the rather rare purple mineral pigment, caput mortuum, hitherto reported in only a few Roman villas elsewhere in mainland Europe, is in evidence in this early phase settlement and the use of gypsum as a special ground preparation agent as an additive to the more common limewash putty to enhance the effect of the use of lazurite as a pigment is worthy of note in this context. Otherwise, the pigments are seen to be those that are quite normally encountered in Roman villas, namely, haematite, goethite, terre verte, and carbon. The results of this study indicate that at Colchester there was a continued development in technique into the colonial phase compared with a stagnation in Lincoln; these scientific results have created a stimulus for further historical research into pigment and techniques development for wall paintings at the fringe of the Roman Empire in the 1st-3rd Centuries AD.

A Spectroscopic Orbit for the Late-type Be Star β CMi

NASA Astrophysics Data System (ADS)

Dulaney, Nicholas A.; Richardson, Noel D.; Gerhartz, Cody J.; Bjorkman, J. E.; Bjorkman, K. S.; Carciofi, Alex C.; Klement, Robert; Wang, Luqian; Morrison, Nancy D.; Bratcher, Allison D.; Greco, Jennifer J.; Hardegree-Ullman, Kevin K.; Lembryk, Ludwik; Oswald, Wayne L.; Trucks, Jesica L.

2017-02-01

The late-type Be star β CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. These results showed that the disk is likely truncated at a finite radius from the star, which Klement et al. suggest is evidence for an unseen binary companion in orbit. Here we report on an analysis of the Ritter Observatory spectroscopic archive of β CMi to search for evidence of the elusive companion. We detect periodic Doppler shifts in the wings of the Hα line with a period of 170 days and an amplitude of 2.25 km s-1, consistent with a low-mass binary companion (M ≈ 0.42 M ⊙). We then compared small changes in the violet-to-red peak height changes (V/R) with the orbital motion. We find weak evidence that it does follow the orbital motion, as suggested by recent Be binary models by Panoglou et al. Our results, which are similar to those for several other Be stars, suggest that β CMi may be a product of binary evolution where Roche lobe overflow has spun up the current Be star, likely leaving a hot subdwarf or white dwarf in orbit around the star. Unfortunately, no direct sign of this companion star is found in the very limited archive of International Ultraviolet Explorer spectra.

Romano-British wall paintings: Raman spectroscopic analysis of fragments from two urban sites of early military colonisation

NASA Astrophysics Data System (ADS)

Edwards, H. G. M.; Middleton, P. S.; Hargreaves, M. D.

2009-08-01

Raman spectroscopic analyses of 1st century AD Romano-British villa wall-painting fragments from two important military and early urban centres at Colchester and Lincoln have demonstrated some interesting contrasts in technique and palette usage. Colchester, the earliest fortified settlement, developed a sophisticated painting and craft industry compared with Lincoln in the assimilation of novel substrate preparation ideas and pigment adoption. The earliest use of the rather rare purple mineral pigment, caput mortuum, hitherto reported in only a few Roman villas elsewhere in mainland Europe, is in evidence in this early phase settlement and the use of gypsum as a special ground preparation agent as an additive to the more common limewash putty to enhance the effect of the use of lazurite as a pigment is worthy of note in this context. Otherwise, the pigments are seen to be those that are quite normally encountered in Roman villas, namely, haematite, goethite, terre verte, and carbon. The results of this study indicate that at Colchester there was a continued development in technique into the colonial phase compared with a stagnation in Lincoln; these scientific results have created a stimulus for further historical research into pigment and techniques development for wall paintings at the fringe of the Roman Empire in the 1st-3rd Centuries AD.

A Comparative Study of Gold Bonding via Electronic Spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Ruohan

The bonding and electrostatic properties of gold containing molecules are highly influenced by relativistic effects. To understand this facet on bonding, a series of simple diatomic AuX (X=F, Cl, O and S) molecules, where upon bond formation the Au atom donates or accepts electrons, was investigated and discussed in this thesis. First, the optical field-free, Stark, and Zeeman spectroscopic studies have been performed on AuF and AuCl. The simple polar bonds between Au and typical halogens (i.e. F and Cl) can be well characterized by the electronic structure studies and the permanent electric dipole moments, mu el. The spectroscopic parameters have been precisely determined for the [17.7]1, [17.8]0+ and X1Sigma + states of AuF, and the [17.07]1, [17.20]0+ and X1Sigma+ states of AuCl. The mu el have been determined for ground and excited states of AuF and AuCl. The results from the hyperfine analysis and Stark measurement support the assignments that the [17.7]1 and [17.8]0+ states of AuF are the components of a 3pi state. Similarly, the analysis demonstrated the [19.07]1 and [19.20]0+ states are the components of the 3pi state of AuCl. Second, my study focused on AuO and AuS because the bonding between gold and sulfur/oxygen is a key component to numerous established and emerging technologies that have applications as far ranging as medical imaging, catalysis, electronics, and material science. The high-resolution spectra were record and analyzed to obtain the geometric and electronic structural data for the ground and excited states. The electric dipole moment, muel , and the magnetic dipole moment, mum, has been the precisely measured by applying external static electric and magnetic fields. muel and mum are used to give insight into the unusual complex bonding in these molecules. In addition to direct studies on the gold-containing molecules, other studies of related molecules are included here as well. These works contain the pure rotation measurement of PtC, the hyperfine and Stark spectroscopic studies of PtF, and the Stark and Zeeman spectroscopic studies of MgH and MgD. Finally, a perspective discussion and conclusion will summarize the results of AuF, AuCl, AuO, and AuS from this work (bond lengths, dipole moment, etc.). The highly quantitative information derived from this work is the foundation of a chemical description of matter and essential for kinetic energy manipulation via Stark and Zeeman interactions. This data set also establishes a synergism with computation chemists who are developing new methodologies for treating relativistic effects and electron correlation.

A Parallel Spectroscopic Method for Examining Dynamic Phenomena on the Millisecond Time Scale

PubMed Central

Snively, Christopher M.; Chase, D. Bruce; Rabolt, John F.

2009-01-01

An infrared spectroscopic technique based on planar array infrared (PAIR) spectroscopy has been developed that allows the acquisition of spectra from multiple samples simultaneously. Using this technique, it is possible to acquire spectra over a spectral range of 950–1900cm−1 with a temporal resolution of 2.2ms. The performance of this system was demonstrated by determining the shear-induced orientational response of several low molecular weight liquid crystals. Five different liquid crystals were examined in combination with five different alignment layers, and both primary and secondary screens were demonstrated. Implementation of this high throughput PAIR technique resulted in a reduction in acquisition time as compared to both step-scan and ultra-rapid-scanning FTIR spectroscopy. PMID:19239197

The Optical Counterpart of M101 ULX-1

NASA Technical Reports Server (NTRS)

Kuntz, K. D.; Gruendi, Robert A.; Chu, You-Hua; Chen, C.-H. Rosie; Still, Martin; Mukai, Koji; Musuotzky, Richard F.

2004-01-01

We have identified the optical counterpart of the Ultra-Luminous X-ray source Ml0l ULX-1 (CX- OKM101 J140332.74+542102), by comparing HST ACS images with Chandra ACIS-S images. The optical counterpart has V= 23.75 and colours consistent with those for a mid-B supergiant. Archival WFPC2 observations show that the source brightness is constant to within approximately 0.1 mag. The physical association of this source with the ULX is confirmed by Gemini GMOS spectroscopic observations which show spatially unresolved He II lambda4686 and He I lambda5876 emission. These results suggest that M10l ULX-1 is a HMXB but deep spectroscopic monitoring observations are needed to determine the detailed properties of this system.

Spectroscopic observations of V443 Herculis - A symbiotic binary with a low mass white dwarf

NASA Technical Reports Server (NTRS)

Dobrzycka, Danuta; Kenyon, Scott J.; Mikolajewska, Joanna

1993-01-01

We present an analysis of new and existing photometric and spectroscopic observations of the symbiotic binary V443 Herculis. This binary system consists of a normal M5 giant and a hot compact star. These two objects have comparable luminosities: about 1500 solar for the M5 giant and about 1000 solar for the compact star. We identify three nebular regions in this binary: a small, highly ionized volume surrounding the hot component, a modestly ionized shell close to the red giant photosphere, and a less dense region of intermediate ionization encompassing both binary components. The system parameters for V443 Her suggest the hot component currently declines from a symbiotic nova eruption.

Structural Characteristics and Reactivity Relationships of Nitroaromatic and Nitramine Explosives – A Review of Our Computational Chemistry and Spectroscopic Research

PubMed Central

Qasim, Mohammad M.; Moore, Brett; Taylor, Lyssa; Honea, Patricia; Gorb, Leonid; Leszczynski, Jerzy

2007-01-01

Although much has been discovered, discussed and written as to problems of contamination by various military unique compounds, particularly by the nitrogen based energetics (NOCs), remaining problems dictate further evaluation of actual and potential risk to the environment by these energetics and their derivatives and metabolites through determination of their environmental impact—transport, fate and toxicity. This work comprises an effort to understand structural relationships and degradation mechanisms of current and emerging explosives, including nitroaromatic; cyclic and cage cyclic nitramine; and a nitrocubane. This review of our computational chemistry and spectroscopic research describes and compares competitive degradation mechanisms by free radical oxidative, reductive and alkali hydrolysis, relating them, when possible, to environmental risk.

Catalysts at work: From integral to spatially resolved X-ray absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grunwaldt, Jan-Dierk; Kimmerle, Bertram; Baiker, Alfons

2009-09-25

Spectroscopic studies on heterogeneous catalysts have mostly been done in an integral mode. However, in many cases spatial variations in catalyst structure can occur, e.g. during impregnation of pre-shaped particles, during reaction in a catalytic reactor, or in microstructured reactors as the present overview shows. Therefore, spatially resolved molecular information on a microscale is required for a comprehensive understanding of theses systems, partly in ex situ studies, partly under stationary reaction conditions and in some cases even under dynamic reaction conditions. Among the different available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the differentmore » selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure and the distribution of Cu(0), Cu(I), Cu(II) species in a Cu/ZnO catalyst loaded in a quartz capillary microreactor could be reconstructed quantitatively on a virtual section through the reactor. An illustrating example for spatially resolved XAS under reaction conditions is the partial oxidation of methane over noble metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used to efficiently determine the distribution of the oxidation state of a catalyst inside a reactor under reaction conditions. The new technical approaches together with quantitative data analysis and an appropriate in situ catalytic experiment allowed drawing important conclusions on the reaction mechanism, and the analytical strategy might be similarly applied in other case studies. The corresponding temperature profiles and the catalytic performance were measured by means of an IR-camera and mass spectrometric analysis. In a more advanced experiment the ignition process of the partial oxidation of methane was followed in a spatiotemporal manner which demonstrates that spatially resolved spectroscopic information can even be obtained in the subsecond scale.« less

Silver sulfadoxinate: Synthesis, structural and spectroscopic characterizations, and preliminary antibacterial assays in vitro

NASA Astrophysics Data System (ADS)

Zanvettor, Nina T.; Abbehausen, Camilla; Lustri, Wilton R.; Cuin, Alexandre; Masciocchi, Norberto; Corbi, Pedro P.

2015-02-01

The sulfa drug sulfadoxine (SFX) reacted with Ag+ ions in aqueous solution, affording a new silver(I) complex (AgSFX), which was fully characterized by chemical, spectroscopic and structural methods. Elemental, ESI-TOF mass spectrometric and thermal analyses of AgSFX suggested a [Ag(C12H13N4O2S)] empirical formula. Infrared spectroscopic measurements indicated ligand coordination to Ag(I) through the nitrogen atoms of the (deprotonated) sulfonamide group and by the pyrimidine ring, as well as through oxygen atom(s) of the sulfonamide group. These hypotheses were corroborated by 13C and 15N SS-NMR spectroscopy and by an unconventional structural characterization based on X-ray powder diffraction data. The latter showed that AgSFX crystallizes as centrosymmetric dimers with a strong Ag⋯Ag interaction of 2.7435(6) Å, induced by the presence of exo-bidentate N,N‧ bridging ligands and the formation of an eight-membered ring of [AgNCN]2 sequence, nearly planar. Participation of oxygen atoms of the sulfonamide residues generates in the crystal a 1D coordination polymer, likely responsible for its very limited solubility in all common solvents. Besides the analytical, spectroscopic and structural description, the antibacterial properties of AgSFX were assayed using disc diffusion methods against Escherichia coli and Pseudomonas aeruginosa (Gram-negative), and Staphylococcus aureus (Gram-positive) bacterial strains. The AgSFX complex showed to be active against Gram-positive and Gram-negative bacterial strains, being comparable to the activities of silver sulfadiazine.

Development of a Tandem Electrodynamic Trap Apparatus for Merging Charged Droplets and Spectroscopic Characterization of Resultant Dried Particles.

PubMed

Kohno, Jun-Ya; Higashiura, Tetsu; Eguchi, Takaaki; Miura, Shumpei; Ogawa, Masato

2016-08-11

Materials work in multicomponent forms. A wide range of compositions must be tested to obtain the optimum composition for a specific application. We propose optimization using a series of small levitated single particles. We describe a tandem-trap apparatus for merging liquid droplets and analyzing the merged droplets and/or dried particles that are produced from the merged droplets under levitation conditions. Droplet merging was confirmed by Raman spectroscopic studies of the levitated particles. The tandem-trap apparatus enables the synthesis of a particle and spectroscopic investigation of its properties. This provides a basis for future investigation of the properties of levitated single particles.

Spectroscopic Study of the Early-Type Binary HX Vel A

NASA Astrophysics Data System (ADS)

Özkardeş, Burcu; Sürgit, Derya; Erdem, Ahmet; Budding, Edwin; Soydugan, Faruk; Demircan, Osman

2012-04-01

This paper presents high resolution spectroscopy of the HX Vel (IDS 08390-4744 AB) multiple system. New spectroscopic observations of the system were made at Mt. John University Observatory in 2007 and 2008. Radial velocities of both components of HX Vel A were measured using gaussian fitting. The spectroscopic mass ratio of the close binary was determined as 0.599+/-0.052, according to a Keplerian orbital solution. The resulting orbital elements are a1sini=0.0098+/-0.0003 AU, a2sini=0.0164+/-0.0003 AU, M1sin3i=1.19+/-0.07 M⊙ and M2sin3i=0.71+/-0.04 M⊙.

Effective binding of perhalogenated closo-borates to serum albumins revealed by spectroscopic and ITC studies

NASA Astrophysics Data System (ADS)

Kuperman, Marina V.; Losytskyy, Mykhaylo Yu.; Bykov, Alexander Yu.; Yarmoluk, Sergiy M.; Zhizhin, Konstantin Yu.; Kuznetsov, Nikolay T.; Varzatskii, Oleg A.; Gumienna-Kontecka, Elzbieta; Kovalska, Vladyslava B.

2017-08-01

The interactions of boron cluster compounds closo-borates with biomolecules are widely studied due to their efficiency as agents for boron neutron capture therapy of cancer. In present work the binding abilities of anionic halogen closo-borates [B10Hal10]2- (Hal = Cl, Br, I) and [B12Hal12]2- (Hal = Cl, I) towards bovine and human serum albumins were investigated by spectroscopic and isothermal titration calorimetry (ITC) methods. The protein fluorescence quenching method and ITC studies confirmed the complex formation. The degree of protein fluorescence quenching increased from chlorine to iodine boron derivatives that is attributed to external heavy atom effect. The ITC data point on the existence in the protein structure of two types of binding sites: with higher and lower affinity to closo-borates. Albumin-closo-borate complex binding ratio, n (4-5 anions per protein molecule) is higher than for the parent hydrogen closo-borates (2 anions per protein molecule). Binding constants estimated by fluorescent and ITC methods indicate higher affinity of halogen closo-borates to albumins (K in the range of 104-106 M-1) comparing to that of the hydrogen closo-borate (K about 103 M-1). Due to their high affinity and high binding ratio to albumins halogen closo-borates are proposed for further studies as agents for boron neutron capture therapy.

Molecular investigation on the interaction of spermine with proteinase K by multispectroscopic techniques and molecular simulation studies.

PubMed

Hosseini-Koupaei, Mansoore; Shareghi, Behzad; Saboury, Ali Akbar; Davar, Fateme

2017-01-01

The alteration in structure, function and stability of proteinase K in the presence of spermine was investigated using spectroscopic methods and simulation techniques. The stability and enzyme activity of proteinase K-spermine complex were significantly enhanced as compared to that of the pure enzyme. The increase in the value of V max and the catalytic efficiency of Proteinase K in presence of spermine confirmed that the polyamine could bring the enzyme hyperactivation. UV-vis spectroscopy, intrinsic fluorescence and circular dichroism methods demonstrated that the binding of spermine changed the microenvironment and structure of proteinase K. The fluorescence studies, showing that spermine quenched the intensity of proteinase K with static mechanism. Thermodynamic parameters analysis suggested that hydrogen bond and van der Waals forces play a key role in complex stability which is in agreement with modeling studies. The CD spectra represented the secondary structure alteration of proteinase K with an increase in α-helicity and a decrease in β-sheet of proteinase K upon spermine conjugation. The molecular simulation results proposed that spermine could interact with proteinase K spontaneously at single binding site, which is in agreement with spectroscopic results. This agreement between experimental and theoretical results may be a worth method for protein-ligand complex studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Spectroscopic characterization of the iron-oxo intermediate in cytochrome P450.

PubMed

Jung, Christiane; Schünemann, Volker; Lendzian, Friedhelm; Trautwein, Alfred X; Contzen, Jörg; Galander, Marcus; Böttger, Lars H; Richter, Matthias; Barra, Anne-Laure

2005-10-01

From analogy to chloroperoxidase from Caldariomyces fumago, it is believed that the electronic structure of the intermediate iron-oxo species in the catalytic cycle of cytochrome P450 corresponds to an iron(IV) porphyrin-pi-cation radical (compound I). However, our recent studies on P450cam revealed that after 8 ms a tyrosine radical and iron(IV) were formed in the reaction of ferric P450 with external oxidants in the shunt pathway. The present study on the heme domain of P450BM3 (P450BMP) shows a similar result. In addition to a tyrosine radical, a contribution from a tryptophan radical was found in the electron paramagnetic resonance (EPR) spectra of P450BMP. Here we present comparative multi-frequency EPR (9.6, 94 and 285 GHz) and Mössbauer spectroscopic studies on freeze-quenched intermediates produced using peroxy acetic acid as oxidant for both P450 cytochromes. After 8 ms in both systems, amino acid radicals occurred instead of the proposed iron(IV) porphyrin-pi-cation radical, which may be transiently formed on a much faster time scale. These findings are discussed with respect to other heme thiolate proteins. Our studies demonstrate that intramolecular electron transfer from aromatic amino acids is a common feature in these enzymes. The electron transfer quenches the presumably transiently formed porphyrin-pi-cation radical, which makes it extremely difficult to trap compound I.

THE SPLASH SURVEY: A SPECTROSCOPIC ANALYSIS OF THE METAL-POOR, LOW-LUMINOSITY M31 dSph SATELLITE ANDROMEDA X ,

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalirai, Jason S.; Zucker, Daniel B.; Kniazev, Alexei Y.

2009-11-01

Andromeda X (And X) is a newly discovered low-luminosity M31 dwarf spheroidal galaxy (dSph) found by Zucker et al. in the Sloan Digital Sky Survey (SDSS; York et al.). In this paper, we present the first spectroscopic study of individual red giant branch stars in And X, as a part of the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) Survey. Using the Keck II telescope and multiobject DEIMOS spectrograph, we target two spectroscopic masks over the face of the galaxy and measure radial velocities for approx100 stars with a median accuracy of sigma {sub v} approx 3 kmmore » s{sup -1}. The velocity histogram for this field confirms three populations of stars along the sight line: foreground Milky Way dwarfs at small negative velocities, M31 halo red giants over a broad range of velocities, and a very cold velocity 'spike' consisting of 22 stars belonging to And X with v {sub rad} = -163.8 +- 1.2 km s{sup -1}. By carefully considering both the random and systematic velocity errors of these stars (e.g., through duplicate star measurements), we derive an intrinsic velocity dispersion of just sigma {sub v} = 3.9 +- 1.2 km s{sup -1} for And X, which for its size, implies a minimum mass-to-light ratio of M/L{sub V} = 37{sup +26} {sub -19} assuming that the mass traces the light. Based on the clean sample of member stars, we measure the median metallicity of And X to be [Fe/H] = -1.93 +- 0.11, with a slight radial metallicity gradient. The dispersion in metallicity is large, sigma([Fe/H]{sub phot}) = 0.48, possibly hinting that the galaxy retained much of its chemical enrichment products. And X has a total integrated luminosity (M{sub V} = -8.1 +- 0.5) that straddles the classical Local Group dSphs and the new SDSS ultra-low luminosity galaxies. The galaxy is among the most metal-poor dSphs known, especially relative to those with M{sub V} < -8, and has the second lowest intrinsic velocity dispersion of the entire sample. Our results suggest that And X is less massive by a factor of 4 when compared to Milky Way dSphs of comparable luminosity (e.g., Draco and Ursa Minor). We discuss the potential for better understanding the formation and evolution mechanisms for M31's system of dSphs through (current) kinematic and chemical abundance studies, especially in relation to the Milky Way sample.« less

Theoretical infrared and electronic absorption spectra of C16H10 isomers, their ions and doubly ions

NASA Astrophysics Data System (ADS)

Naganathappa, Mahadevappa; Chaudhari, Ajay

2012-09-01

Polycyclic aromatic hydrocarbons (PAHs) or PAH-related molecules are considered to be responsible for the unidentified infrared (UIR) emission features at 3.3, 6.2, 7.7, 8.6 and 11.2 μm. However, the exact identification of PAH or PAH-related molecules is difficult. There have been several investigations on the spectroscopic characterization of PAH molecules. But none of them compared the spectra of isomers of PAHs, which might have help in the identification of the UIR emission features. This work presents the infrared and electronic absorption spectra of isomers of C16H10. The aim of the present work is to compare infrared and electronic absorption spectra of four isomers of C16H10 PAH viz. pyrene, aceanthrylene, acephenanthrylene and fluoranthene, their ions and doubly ions. We also compare the spectra of pyrene in the gas-phase and in H2O ice. We have used the density functional theory with B3LYP exchange and correlation functional and 6-311++g** basis set to study the infrared spectra. The time-dependent density functional theory (TDDFT) has been used to obtain the electronic absorption spectra. Significant difference in the CC stretching, CH in-plane bending and CH out-of-plane bending vibration modes is observed for the isomers of C16H10 whereas there is no large difference in the CH stretching vibration band. A significant change in the vibrational band is observed for pyrene in H2O ice compared to gas-phase pyrene. Though isomers of C16H10 PAH have the same number of carbon and hydrogen atoms, their spectroscopic characteristics are different. This study should help in identifying the isomers of C16H10, their ions and doubly cation in the interstellar medium.

Vibrational spectroscopic study of fluticasone propionate

NASA Astrophysics Data System (ADS)

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

2009-03-01

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

VUV Spectroscopic Study of the D 1Π u State of Molecular Deuterium

NASA Astrophysics Data System (ADS)

Dickenson, G. D.; Ivanov, T. I.; Ubachs, W.; Roudjane, M.; de Oliveira, N.; Joyeux, D.; Nahon, L.; Tchang-Brillet, W.-Ü. L.; Glass-Maujean, M.; Schmoranzer, H.; Knie, A.; Kübler, S.; Ehresmann, A.

2011-11-01

The D 1Π u - ? absorption system of molecular deuterium has been re-investigated using the VUV Fourier-Transform (FT) spectrometer at the DESIRS beamline of the synchrotron SOLEIL and photon-induced fluorescence spectrometry (PIFS) using the 10 m normal incidence monochromator at the synchrotron BESSY II. Using the FT spectrometer absorption spectra in the range 72-82 nm were recorded in quasi static gas at 100 K and in a free flowing jet at a spectroscopic resolution of 0.50 and 0.20 cm-1 respectively. The narrow Q-branch transitions, probing states of Π- symmetry, were observed up to vibrational level v = 22. The states of Π+ symmetry, known to be broadened due to predissociation and giving rise to asymmetric Beutler-Fano resonances, were studied up to v = 18. The 10 m normal incidence beamline setup at BESSY II was used to simultaneously record absorption, dissociation, ionization and fluorescence decay channels from which information on the line intensities, predissociated widths, and Fano q-parameters were extracted. R-branch transitions were observed up to v = 23 for J = 1-3 as well as several transitions for J = 4 and 5 up to v = 22 and 18 respectively. The Q-branch transitions are found to weakly predissociate and were observed from v = 8 to the final vibrational level of the state v = 23. The spectroscopic study is supported by two theoretical frameworks. Results on the Π- symmetry states are compared to ab initio multi-channel-quantum defect theory (MQDT) calculations, demonstrating that these calculations are accurate to within 0.5 cm-1. Furthermore, the calculated line intensities of Q-lines agree well with measured values. For the states of Π+ symmetry a perturbative model based on a single bound state interacting with a predissociation continuum was explored, yielding good agreement for predissociation widths, Fano q-parameters and line intensities.

A Magellan M2FS Spectroscopic Survey of Galaxies at 5.5 < z < 6.8: Program Overview and a Sample of the Brightest Lyα Emitters

NASA Astrophysics Data System (ADS)

Jiang, Linhua; Shen, Yue; Bian, Fuyan; Zheng, Zhen-Ya; Wu, Jin; Oyarzún, Grecco A.; Blanc, Guillermo A.; Fan, Xiaohui; Ho, Luis C.; Infante, Leopoldo; Wang, Ran; Wu, Xue-Bing; Mateo, Mario; Bailey, John I., III; Crane, Jeffrey D.; Olszewski, Edward W.; Shectman, Stephen; Thompson, Ian; Walker, Matthew G.

2017-09-01

We present a spectroscopic survey of high-redshift, luminous galaxies over four square degrees on the sky, aiming to build a large and homogeneous sample of Lyα emitters (LAEs) at z≈ 5.7 and 6.5, and Lyman-break galaxies (LBGs) at 5.5< z< 6.8. The fields that we choose to observe are well studied, such as by the Subaru XMM-Newton Deep Survey and COSMOS. They have deep optical imaging data in a series of broad and narrow bands, allowing for the efficient selection of galaxy candidates. Spectroscopic observations are being carried out using the multi-object spectrograph M2FS on the Magellan Clay telescope. M2FS is efficient enough to identify high-redshift galaxies, owing to its 256 optical fibers deployed over a circular field of view 30\\prime in diameter. We have observed ˜2.5 square degrees. When the program is completed, we expect to identify more than 400 bright LAEs at z≈ 5.7 and 6.5, and a substantial number of LBGs at z≥slant 6. This unique sample will be used to study a variety of galaxy properties and to search for large protoclusters. Furthermore, the statistical properties of these galaxies will be used to probe cosmic reionization. We describe the motivation, program design, target selection, and M2FS observations. We also outline our science goals, and present a sample of the brightest LAEs at z≈ 5.7 and 6.5. This sample contains 32 LAEs with Lyα luminosities higher than 1043 erg s-1. A few of them reach ≥3 × 1043 erg s-1, comparable to the two most luminous LAEs known at z≥slant 6, “CR7” and “COLA1.” These LAEs provide ideal targets to study extreme galaxies in the distant universe.

Spectroscopic and quantum chemical study of the structure of a new paramagnetic dimeric palladium(II,III) complex with creatine

NASA Astrophysics Data System (ADS)

Mitewa, Mariana; Enchev, Venelin; Bakalova, Tatyana

2002-05-01

The structure and coordination mode of the newly synthesized dimeric paramagnetic Pd(II,III) complex are studied using magneto-chemical, EPR and IR spectroscopic methods. In order to perform reliable assignment of the IR bands, the structure and IR spectrum of the free creatine were calculated using ab initio method. For calculation of the configuration of its deprotonated and doubly deprotonated forms the semiempirical AM1 method was used.

Spectroscopic ellipsometry study on E2 peak splitting of Si-Ge short period superlattices

NASA Astrophysics Data System (ADS)

Kim, Y. D.; Klein, M. V.; Baribeau, J.-M.; Hwang, S. H.; Whang, K. W.; Yoon, E.

1997-06-01

We report spectroscopic ellipsometry (SE) studies on (Si)2(Ge)12, (Si)6(Ge)2, and (Si)12(Ge)2 short period superlattices (SLs) whose optical response has not been reported yet. Multilayer calculations enabled us to determine the dielectric response of the superlattice layers. We report the clear observation of splitting of the E2 peak in (Si)m(Ge)n superlattices contrary to the previous SE report that the separation was observed only in larger period SLs.

The H2O-CH3F Complex: a Combined Microwave and Infrared Spectroscopic Study Supported by Structure Calculations

NASA Astrophysics Data System (ADS)

Gnanasekar, Sharon Priya; Goubet, Manuel; Arunan, Elangannan; Georges, Robert; Soulard, Pascale; Asselin, Pierre; Huet, T. R.; Pirali, Olivier

2015-06-01

The H2O-CH3F complex could have two geometries, one with a hydrogen bond and one with the newly proposed carbon bond. While in general carbon bonds are weaker than hydrogen bonds, this complex appears to have comparable energies for the two structures. Infrared (IR) and microwave (MW) spectroscopic measurements using, respectively, the Jet-AILES apparatus and the FTMW spectrometer at the PhLAM laboratory, have been carried out to determine the structure of this complex. The IR spectrum shows the formation of the CH3F- H2O hydrogen bonded complex and small red-shifts in OH frequency most probably due to (CH3F)m-(H2O)n clusters. Noticeably, addition of CH_3F in the mixture promotes the formation of small water clusters. Preliminary MW spectroscopic measurements indicate the formation of the hydrogen bonded complex. So far, we have no experimental evidence for the carbon bonded structure. However, calculations of the Ar-CH3F complex show three energetically equivalent structures: a T-shape, a "fluorine" bond and a carbon bond. The MW spectrum of the (Ar)n-CH3F complexes is currently under analysis. Mani, D; Arunan, E. Phys. Chem. Chem. Phys. 2013, 15, 14377. Cirtog, M; Asselin, P; Soulard, P; Tremblay, B; Madebene, B; Alikhani, M. E; Georges, R; Moudens, A; Goubet, M; Huet, T.R; Pirali, O; Roy, P. J. Phys. Chem. A. 2011, 115, 2523 Kassi, S; Petitprez, D; Wlodarczak, G. J. Mol. Struct. 2000, 517-518, 375

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patsourakos, S.; Klimchuk, J. A.; Young, P. R., E-mail: spatsour@cc.uoi.gr, E-mail: james.a.klimchuk@nasa.gov

Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding ≈50 km s{sup –1}. Here, we perform a study of the density of the rapidly upflowing material and compare it with that of the line core that corresponds to the bulk of the plasma. For this task, we use spectroscopic observations of several active regions taken by the Extreme Ultraviolet Imaging Spectrometer of the Hinode mission. The density sensitive ratio of the Fe XIV lines at 264.78 and 274.20more » Å is used to determine wing and core densities. We compute the ratio of the blue wing density to the core density and find that most values are of order unity. This is consistent with the predictions for coronal nanoflares if most of the observed coronal mass is supplied by chromospheric evaporation driven by the nanoflares. However, much larger blue wing-to-core density ratios are predicted if most of the coronal mass is supplied by heated material ejected with type II spicules. Our measurements do not rule out a spicule origin for the blue wing emission, but they argue against spicules being a primary source of the hot plasma in the corona. We note that only about 40% of the pixels where line blends could be safely ignored have blue wing asymmetries in both Fe XIV lines. Anticipated sub-arcsecond spatial resolution spectroscopic observations in future missions could shed more light on the origin of blue, red, and mixed asymmetries.« less

Automatic classification of fluorescence and optical diffusion spectroscopy data in neuro-oncology

NASA Astrophysics Data System (ADS)

Savelieva, T. A.; Loshchenov, V. B.; Goryajnov, S. A.; Potapov, A. A.

2018-04-01

The complexity of the biological tissue spectroscopic analysis due to the overlap of biological molecules' absorption spectra, multiple scattering effect, as well as measurement geometry in vivo has caused the relevance of this work. In the neurooncology the problem of tumor boundaries delineation is especially acute and requires the development of new methods of intraoperative diagnosis. Methods of optical spectroscopy allow detecting various diagnostically significant parameters non-invasively. 5-ALA induced protoporphyrin IX is frequently used as fluorescent tumor marker in neurooncology. At the same time analysis of the concentration and the oxygenation level of haemoglobin and significant changes of light scattering in tumor tissues have a high diagnostic value. This paper presents an original method for the simultaneous registration of backward diffuse reflectance and fluorescence spectra, which allows defining all the parameters listed above simultaneously. The clinical studies involving 47 patients with intracranial glial tumors of II-IV Grades were carried out in N.N. Burdenko National Medical Research Center of Neurosurgery. To register the spectral dependences the spectroscopic system LESA- 01-BIOSPEC was used with specially developed w-shaped diagnostic fiber optic probe. The original algorithm of combined spectroscopic signal processing was developed. We have created a software and hardware, which allowed (as compared with the methods currently used in neurosurgical practice) to increase the sensitivity of intraoperative demarcation of intracranial tumors from 78% to 96%, specificity of 60% to 82%. The result of analysis of different techniques of automatic classification shows that in our case the most appropriate is the k Nearest Neighbors algorithm with cubic metrics.

Reconstructing the colour palette of the Konstantinos Parthenis' burnt paintings.

PubMed

Antonopoulou-Athera, N; Chatzitheodoridis, E; Terlixi, A; Doulgerides, M; Serafetinides, A A

2018-05-09

This case study focuses on the reconstruction of the colour palette and the possibility of laser cleaning of burnt paintings. The paintings ORPHEUS IN THE UNDERWORLD and CONCORDIA, composed by the Greek artist Konstantinos Parthenis (1878-1967), have been severely damaged by fire. The colour palette of Parthenis is thoroughly investigated for the first time, and to perform this, a multi-analytical spectroscopic approach was employed. Non-destructive in situ analysis was performed on multiple areas of the paintings by portable XRF. SEM-EDS and Raman, supported by reflected visible light optical microscopy, and ultraviolet light microscopy, as well as structural XRD and molecular FTIR were performed for identifying the pigments, the binder and the substrate of the paintings. This work also unveiled new aspects of the painting technique used by the artist, such as the uncommon use of multiple pigments of red hue in the upper paint layers, comparatively with the rest of Parthenis' paintings. Molecular spectroscopic techniques (i.e., Raman and FTIR) were effective in identifying pigments like chrome yellow (crocoite mineral), chrome orange (phoenicochroite mineral) and viridian green (hydrated chromium oxide). The spectroscopic analyses were also essential in the laser cleaning restoration because of the detection of pigments (i.e., lead white, vermilion etc.) prone to phase transformations due to photothermal and/or photochemical effects. Our investigation establishes the basis on the application of non-conventional cleaning methods on damaged paintings, such as laser irradiation, in order to remove the damaged layer and/or the superficial accretions, while preserving the hues of the original painting. Copyright © 2018 Elsevier B.V. All rights reserved.

Crystal structure, stability and spectroscopic properties of methane and CO2 hydrates.

PubMed

Martos-Villa, Ruben; Francisco-Márquez, Misaela; Mata, M Pilar; Sainz-Díaz, C Ignacio

2013-07-01

Methane hydrates are highly present in sea-floors and in other planets and their moons. Hence, these compounds are of great interest for environment, global climate change, energy resources, and Cosmochemistry. The knowledge of stability and physical-chemical properties of methane hydrate crystal structure is important for evaluating some new green becoming technologies such as, strategies to produce natural gas from marine methane hydrates and simultaneously store CO2 as hydrates. However, some aspects related with their stability, spectroscopic and other chemical-physical properties of both hydrates are not well understood yet. The structure and stability of crystal structure of methane and CO2 hydrates have been investigated by means of calculations with empirical interatomic potentials and quantum-mechanical methods based on Hartree-Fock and Density Functional Theory (DFT) approximations. Molecular Dynamic simulations have been also performed exploring different configurations reproducing the experimental crystallographic properties. Spectroscopic properties have also been studied. Frequency shifts of the main vibration modes were observed upon the formation of these hydrates, confirming that vibration stretching peaks of C-H at 2915cm(-1) and 2905cm(-1) are due to methane in small and large cages, respectively. Similar effect is observed in the CO2 clathrates. The guest-host binding energy in these clathrates calculated with different methods are compared and discussed in terms of adequacy of empirical potentials and DFT methods for describing the interactions between gas guest and the host water cage, proving an exothermic nature of methane and CO2 hydrates formation process. Copyright © 2013 Elsevier Inc. All rights reserved.

Stellar Color Regression: A Spectroscopy-based Method for Color Calibration to a Few Millimagnitude Accuracy and the Recalibration of Stripe 82

NASA Astrophysics Data System (ADS)

Yuan, Haibo; Liu, Xiaowei; Xiang, Maosheng; Huang, Yang; Zhang, Huihua; Chen, Bingqiu

2015-02-01

In this paper we propose a spectroscopy-based stellar color regression (SCR) method to perform accurate color calibration for modern imaging surveys, taking advantage of millions of stellar spectra now available. The method is straightforward, insensitive to systematic errors in the spectroscopically determined stellar atmospheric parameters, applicable to regions that are effectively covered by spectroscopic surveys, and capable of delivering an accuracy of a few millimagnitudes for color calibration. As an illustration, we have applied the method to the Sloan Digital Sky Survey (SDSS) Stripe 82 data. With a total number of 23,759 spectroscopically targeted stars, we have mapped out the small but strongly correlated color zero-point errors present in the photometric catalog of Stripe 82, and we improve the color calibration by a factor of two to three. Our study also reveals some small but significant magnitude dependence errors in the z band for some charge-coupled devices (CCDs). Such errors are likely to be present in all the SDSS photometric data. Our results are compared with those from a completely independent test based on the intrinsic colors of red galaxies presented by Ivezić et al. The comparison, as well as other tests, shows that the SCR method has achieved a color calibration internally consistent at a level of about 5 mmag in u - g, 3 mmag in g - r, and 2 mmag in r - i and i - z. Given the power of the SCR method, we discuss briefly the potential benefits by applying the method to existing, ongoing, and upcoming imaging surveys.

Accelerated proton echo planar spectroscopic imaging (PEPSI) using GRAPPA with a 32-channel phased-array coil.

PubMed

Tsai, Shang-Yueh; Otazo, Ricardo; Posse, Stefan; Lin, Yi-Ru; Chung, Hsiao-Wen; Wald, Lawrence L; Wiggins, Graham C; Lin, Fa-Hsuan

2008-05-01

Parallel imaging has been demonstrated to reduce the encoding time of MR spectroscopic imaging (MRSI). Here we investigate up to 5-fold acceleration of 2D proton echo planar spectroscopic imaging (PEPSI) at 3T using generalized autocalibrating partial parallel acquisition (GRAPPA) with a 32-channel coil array, 1.5 cm(3) voxel size, TR/TE of 15/2000 ms, and 2.1 Hz spectral resolution. Compared to an 8-channel array, the smaller RF coil elements in this 32-channel array provided a 3.1-fold and 2.8-fold increase in signal-to-noise ratio (SNR) in the peripheral region and the central region, respectively, and more spatial modulated information. Comparison of sensitivity-encoding (SENSE) and GRAPPA reconstruction using an 8-channel array showed that both methods yielded similar quantitative metabolite measures (P > 0.1). Concentration values of N-acetyl-aspartate (NAA), total creatine (tCr), choline (Cho), myo-inositol (mI), and the sum of glutamate and glutamine (Glx) for both methods were consistent with previous studies. Using the 32-channel array coil the mean Cramer-Rao lower bounds (CRLB) were less than 8% for NAA, tCr, and Cho and less than 15% for mI and Glx at 2-fold acceleration. At 4-fold acceleration the mean CRLB for NAA, tCr, and Cho was less than 11%. In conclusion, the use of a 32-channel coil array and GRAPPA reconstruction can significantly reduce the measurement time for mapping brain metabolites. (c) 2008 Wiley-Liss, Inc.

Nondestructive multispectral reflectoscopy between 800 and 1900 nm: An instrument for the investigation of the stratigraphy in paintings.

PubMed

Karagiannis, G; Salpistis, Chr; Sergiadis, G; Chryssoulakis, Y

2007-06-01

In the present work, a powerful tool for the investigation of paintings is presented. This permits the tuneable multispectral real time imaging between 200 and 5000 nm and the simultaneous multispectral acquisition of spectroscopic data from the same region. We propose the term infrared reflectoscopy for tuneable infrared imaging in paintings (Chryssonlakis and Chassery, The Application of Physicochemical Methods of Analysis and Image Processing Techniques to Painted Works of Art, Erasmus Project ICP-88-006-6, Athens, June, 1989) for a technique that is effective especially when the spectroscopic data acquisition is performed between 800 and 1900 nm. Elements such as underdrawings, old damage that is not visible to the naked eye, later interventions or overpaintings, hidden signatures, nonvisible inscriptions, and authenticity features can thus be detected with the overlying paint layers becoming successively "transparent" due to the deep infrared penetration. The spectroscopic data are collected from each point of the studied area with a 5 nm step through grey level measurement, after adequate infrared reflectance (%R) and curve calibration. The detection limits of the infrared detector as well as the power distribution of the radiation coming out through the micrometer slit assembly of the monochromator in use are also taken into account. Inorganic pigments can thus be identified and their physicochemical properties directly compared to the corresponding infrared images at each wavelength within the optimum region. In order to check its effectiveness, this method was applied on an experimental portable icon of a known stratigraphy.

Photoemission study of electronic structure of the half-metallic ferromagnet Co3Sn2S2

NASA Astrophysics Data System (ADS)

Holder, M.; Dedkov, Yu. S.; Kade, A.; Rosner, H.; Schnelle, W.; Leithe-Jasper, A.; Weihrich, R.; Molodtsov, S. L.

2009-05-01

Surface electronic structure of polycrystalline and single-crystalline samples of the half-metallic ferromagnet Co3Sn2S2 was studied by means of angle-resolved and core-level photoemissions. The experiments were performed in temperature regimes both above and below a Curie temperature of 176.9 K. The spectroscopic results are compared to local-spin density approximation band-structure calculations for the bulk samples. It is found that the surface sensitive experimental data are generally reproduced by the bulk computation suggesting that the theoretically predicted half-metallic properties of Co3Sn2S2 are retained at the surface.

Newly Discovered Be Stars in the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Reid, W. A.

2016-11-01

The Large Magellanic Cloud (LMC) is a excellent laboratory in which to analyse and compare the distinctive characteristics of massive and luminous emission-line stars. In particular, the known and almost co-equal distance to all objects greatly assists the study of comparative luminosities. The original UKST Hα survey covering the central 25deg2 of the LMC revealed 518 Be stars, 413 of which were new discoveries. By extending the survey to cover the entire LMC area of 64 deg2, an additional 415 emission-line stars were identified. Most of the additions have now been spectroscopically observed, with the majority being confirmed as Be stars. The flux, equivalent width, and width at half maximum of the main emission-lines for each of the ˜800 spectroscopically observed LMC Be stars were measured in order to understand their elemental composition and the interaction of the extended circumstellar disk. After subtracting foreground or ambient dust and gas emission, 130 or 22% of B stars were classified as type B[e], characterized by the presence of forbidden emission lines such as [SII], [NII], [OIII] and [OII]. With de-reddened data, the first V-band and Hα luminosity functions were constructed for these stars in the LMC. The magnitudes were then compared using U, B, V, I, R, near-IR J, H, K and mid-IR photometry from the Magellanic Cloud Emission-Line Survey, SuperCOSMOS, 2MASS, and WISE where available. Correlations of varying strength between the optical, IR and Hα magnitudes are shown and discussed.