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1

Advances in Quantitative UV-Visible Spectroscopy for Clinical and Pre-clinical Application in Cancer  

PubMed Central

Summary Methods of optical spectroscopy which provide quantitative, physically or physiologically meaningful measures of tissue properties are an attractive tool for the study, diagnosis, prognosis, and treatment of various cancers. Recent development of methodologies to convert measured reflectance and fluorescence spectra from tissue to cancer-relevant parameters such as vascular volume, oxygenation, extracellular matrix extent, metabolic redox states, and cellular proliferation have significantly advanced the field of tissue optical spectroscopy. The number of publications reporting quantitative tissue spectroscopy results in the UV-visible wavelength range has increased sharply in the last 3 years, and includes new and emerging studies which correlate optically-measured parameters with independent measures such as immunohistochemistry, which should aid in increased clinical acceptance of these technologies. PMID:19268567

Brown, J. Quincy; Vishwanath, Karthik; Palmer, Gregory M.; Ramanujam, Nirmala

2009-01-01

2

Multiwavelength UV/visible spectroscopy for the quantitative investigation of platelet quality  

NASA Astrophysics Data System (ADS)

The quality of platelets transfused is vital to the effectiveness of the transfusion. Freshly prepared, discoid platelets are the most effective treatment for preventing spontaneous hemorrhage or for stopping an abnormal bleeding event. Current methodology for the routine testing of platelet quality involves random pH testing of platelet rich plasma and visual inspection of platelet rich plasma for a swirling pattern indicative of the discoid shape of the cells. The drawback to these methods is that they do not provide a quantitative and objective assay for platelet functionality that can be used on each platelet unit prior to transfusion. As part of a larger project aimed at characterizing whole blood and blood components with multiwavelength UV/vis spectroscopy, isolated platelets and platelet in platelet rich plasma have been investigated. Models based on Mie theory have been developed which allow for the extraction of quantitative information on platelet size, number and quality from multi-wavelength UV/vis spectra. These models have been used to quantify changes in platelet rich plasma during storage. The overall goal of this work is to develop a simple, rapid quantitative assay for platelet quality that can be used prior to platelet transfusion to ensure the effectiveness of the treatment. As a result of this work, the optical properties for isolated platelets, platelet rich plasma and leukodepleted platelet rich plasma have been determined.

Mattley, Yvette D.; Leparc, German F.; Potter, Robert L.; Garcia-Rubio, Luis H.

1998-04-01

3

The Use of UV-Visible Reflectance Spectroscopy as an Objective Tool to Evaluate Pearl Quality  

PubMed Central

Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl’s quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry. PMID:22851919

Agatonovic-Kustrin, Snezana; Morton, David W.

2012-01-01

4

Using multiwavelength UV-visible spectroscopy for the characterization of red blood cells: An investigation of hypochromism  

NASA Astrophysics Data System (ADS)

Particle analysis using multiwavelength UV-visible spectroscopy provides the potential for extracting quantitative red blood cell information, such as hemoglobin concentration, cell size, and cell count. However, if there is a significant presence of hypochromism as a result of the concentrated hemoglobin (physiological value of 33%), successful quantification of red cell values would require a correction. Hypochromism has been traditionally defined as a decrease in absorption relative to the values expected from the Beer-Lambert Law due to electronic interactions of chromophores residing in close proximity of one another. This phenomenon has been suggested to be present in macroscopic systems composed of strong chromophores such as nucleic acids, chlorophyll, and hemoglobin. The study presented in this dissertation examines the presence of hypochromism in red blood cells as a part of a larger goal to qualitatively and quantatively characterize red blood cells using multiwavelength UV-visible spectroscopy. The strategy of the study was three-fold: (1) to determine the instrumental configuration that would provide the most complete information in the acquired spectra, (2) to develop an experimental model system in which the hemoglobin content in red blood cells could be modified to various concentrations, and (3) to implement an interpretation model based on light scattering theory (which accounts for both the scattering and absorption components of the optical density spectrum) to provide quantitative information for the experimental system. By this process, hypochromicity was redefined into two categories with molecular hypochromicity representing the traditional definition and macroscopic hypochromicity being an attenuation of the absorption component due to a scattering-related effect. Successful simulations of experimental red cell spectra containing various amounts of hemoglobin were obtained using the theoretical model. Furthermore, successful quantitative interpretation of the red blood cell spectra was achieved in the context of corpuscular hemoglobin concentration, corpuscular volume, and cell count solely by accounting for the scattering and absorption effects of the particle, indicating that molecular hypochromicity was insignificant in this macroscopic system.

Nonoyama, Akihisa

5

Practical wavelength calibration considerations for UV-visible Fourier-transform spectroscopy  

NASA Astrophysics Data System (ADS)

The intrinsic wavelength scale in a modern reference laser-controlled Michelson interferometer-sometimes referred to as the Connes advantage-offers excellent wavelength accuracy with relative ease. Truly superb wavelength accuracy, with total relative uncertainty in line position of the order of several parts in 108, should be within reach with single-point, multiplicative calibration. The need for correction of the wavelength scale arises from two practical off-axis rays propagate through the interferometer, and imperfect geometric alignment of the sample beam with the reference beam and the optical axis of the moving mirror. Although an analytical correction can be made for the finite-aperture effect, calibration with a trusted wavelength standard is typically used to accomplish both corrections. Practical aspects of accurate calibration of an interferometer in the UV-visible region are discussed. Critical issues regarding accurate use of a standard external to the sample source and the evaluation and selection of an appropriate standard are addressed. Anomalous results for two different potential wavelength standards measured by Fabry-Perot interferometry (Ar II and 198 Hg I) are observed. Fourier-transform spectroscopy, wavelength accuracy, wavelength standards, inductively coupled-plasma spectroscopy, spectral interferences, spectral atlas.

Salit, Marc L.; Travis, John C.; Winchester, Michael R.

1996-06-01

6

High sensitivity transient infrared spectroscopy: a UV/Visible transient grating spectrometer with a heterodyne detected infrared probe.  

PubMed

We describe here a high sensitivity means of performing time resolved UV/Visible pump, infrared probe spectroscopy using optically Heterodyne Detected UV-IR Transient Gratings. The experiment design employed is simple, robust and includes a novel means of generating phase locked pulse pairs that relies on only mirrors and a beamsplitter. A signal to noise ratio increase of 24 compared with a conventional pump-probe arrangement is demonstrated. PMID:22714305

Donaldson, Paul M; Strzalka, Halina; Hamm, Peter

2012-06-01

7

Cure characterization of an unsaturated polyester resin using near-infrared, fluorescence and UV/visible reflection spectroscopies  

NASA Astrophysics Data System (ADS)

This dissertation seeks to characterize the cure reaction of an unsaturated polyester resin using near-infrared, fluorescence and UV/Visible reflection spectroscopies. The results will provide a foundation for developing fiber-optic in-situ cure monitoring techniques based on near-infrared, fluorescence, and UV/Visible reflection spectroscopies for an unsaturated polyester resin system. Near-infrared spectra of the unsaturated polyester resin during cure showed a decrease in absorption at 1629, 2087, 2117, and 2227 nm. Model compounds representing the reactants and products of the cure reaction were characterized, and assignment of peaks in the NIR were made. Conversion of styrene and vinylene, determined from NIR measurements, were compared with values obtained using conventional FTIR measurements. Discrepancies between conversion values determined from NIR and FTIR measurements were attributed to a difference in sample sizes used for measurement. Using a microgel based reaction mechanism, the effects of temperature on the conversion of styrene and vinylene was discussed. A strong fluorescence emission was found during cure of the unsaturated polyester resin. As the reaction proceeded, the emission intensity at 306 nm increased. Model compound studies confirmed that the unsaturated polyester vinylene component exhibits negligible fluorescence when excited at 250 nm. The fluorescence emission at 306 nm was attributed to a reduced self-quenching effect of styrene monomer. In-situ fluorescence characterization of the cure reaction was also attempted. Fiber-optic fluorescence measurements taken in-situ at 75°C were found to be higher than those taken by fiber-optics at room temperature, indicating a temperature effect on the fluorescence emission. These results may be a consequence of the static quenching behavior of styrene monomer. UV/Visible reflection spectra of styrene showed a decrease in the % Reflectance at 255 nm with reaction time. This decrease was attributed to an overall reduction in the absorption index as styrene reacts to form polystyrene. Conversion of styrene calculated from UV/Visible reflection and FTIR measurements were in close agreement. A preliminary investigation into the use of UV/Visible reflection spectroscopy to cure monitor a styrene containing unsaturated polyester resin was also performed. A similar decrease in the % Reflectance at 255 nm with cure time was reported for the unsaturated polyester resin.

Grunden, Bradley Lyn

8

Characterization of biochar-derived dissolved organic matter using UV-visible absorption and excitation-emission fluorescence spectroscopies.  

PubMed

In recent years, biochar has become of considerable interest for a variety of environmental applications. However, the feasibility of its application is entirely dependent on its physical and chemical properties, including the characteristics of biochar-derived dissolved organic matter (DOM). The goal of this study was to assess the use of optical analysis for the purpose of characterizing biochar-derived DOM. Three different biochars (slow pyrolysis birch and maple; fast pyrolysis maple) were produced and leached in distilled water over 17d. Samples were taken on days 3, 10, 13 and 17, filtered, and analyzed for DOC content. Samples were also subjected to optical analysis using UV-visible absorption and excitation-emission matrix (EEM) fluorescence spectroscopies. EEM fluorescence data were further analyzed using parallel factor analysis (PARAFAC). Absorbance and fluorescence results were combined and examined using principal component analysis (PCA). Significant differences in the water soluble organic carbon content were observed for all biochar types. The estimated aromaticity (SUVA254) and mean molecular weight (S275-295) of biochar-derived DOM were also found to differ based on biochar type. PARAFAC analysis identified three humic-like components and one protein-like component. Distinct DOM signatures were observed for each biochar type. Transformations in biochar DOM characteristics over time were also observed. The PCA showed a clear delineation in biochar types based on their optical properties. The results of this study indicate that optical analysis may provide valuable information regarding the characteristics of biochar-derived DOM. PMID:24359913

Jamieson, Tyler; Sager, Eric; Guéguen, Céline

2014-05-01

9

Quantitative determination of molecular structure in multilayered thin films of biaxial and lower symmetry from photon spectroscopies. I. Reflection  

E-print Network

symmetry from photon spectroscopies. I. Reflection infrared vibrational spectroscopy Atul N. Parikh-ray reflectivity, uv-visible spectroscopic ellipsometry, and infrared reflection spectroscopy. Further, the theory spectroscopy and involves quantitative decomposition of the isotropic imaginary optical function (k) spectrum

Parikh, Atul N.

10

Extent of Reduction of Vanadium Oxides during Catalytic Oxidation of Alkanes Measured by in-Situ UV-Visible Spectroscopy  

E-print Network

Extent of Reduction of Vanadium Oxides during Catalytic Oxidation of Alkanes Measured by in-Situ UV to oxidation reactions using lattice oxygens as reactive intermediates. Introduction Oxidative alkane-visible spectroscopy probes the electronic structure of oxide domains commonly used in alkane ODH catalysis.6

Bell, Alexis T.

11

Electropolymerizable 2,2?-Carboranyldithiophenes. Structure–Property Investigations of the Corresponding Conducting Polymer Films by Electrochemistry, UV–Visible Spectroscopy and Conducting Probe Atomic Force Microscopy  

PubMed Central

Carborane-functionalized conducting polymer films have been electrogenerated in dichloromethane from the anodic oxidation of ortho- (1), meta- (3) and para-carborane (4) isomers linked to two 2-thienyl units. The corresponding electrochemical response was characterized by a broad reversible redox system corresponding to the p-doping/undoping of the polythiophene backbone, the formal potential of which increased in the order poly(1) < poly(3) < poly(4), from ca. 0.50 to 1.15 V vs Ag/Ag+ 10?2 M. From further UV–visible spectroscopy analysis, the optical band gap was estimated at 1.8, 2.0 and 2.2 eV for poly(1), poly(3) and poly(4), respectively. The more conjugated and electroconductive character of poly(1) is ascribed to a more planar conformation of the conjugated backbone resulting from an intramolecular ?–?? cyclization reaction in the monomer, consequently yielding a fused conjugated polymer. Molecular modeling calculations using the DFT method support this hypothesis. The surface topography and maps of the conductive domains of the electropolymerized films were evaluated by conducting probe AFM. The three polymers exhibit fairly similar morphological characteristics and a surface roughness of ~2 nm. Current–voltage (I–V) characteristics of conducting AFM tip-carborane polymer–ITO junctions showed that poly(1) had the highest conductivity. PMID:21399746

Barrière, Frédéric; Fabre, Bruno; Hao, Erhong; LeJeune, Zorabel M.; Hwang, Euiyong; Garno, Jayne C.; Nesterov, Evgueni E.; Vicente, M. Graça H.

2010-01-01

12

FT-IR, FT-Raman, UV-Visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol  

NASA Astrophysics Data System (ADS)

In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G? basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated 1H NMR and 13C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations.

Chain, Fernando E.; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandán, Silvia A.

2015-03-01

13

FT-IR, FT-Raman, UV-Visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol.  

PubMed

In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G(?) basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated (1)H NMR and (13)C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations. PMID:25498827

Chain, Fernando E; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandán, Silvia A

2015-03-01

14

Ionization constants and thermal stabilities of uracil and adenine under hydrothermal conditions as measured by in situ UV-visible spectroscopy  

NASA Astrophysics Data System (ADS)

UV-visible spectra for aqueous uracil and adenine were measured in a high-pressure platinum flow cell with sapphire windows at temperatures up to 250 °C at a constant pressure of 7.2 MPa. Ionization constants were determined from pH-dependent spectra in the buffer solutions NH3/NH4Cl, NaHCO3/Na2CO3, HCOOH/NaHCOO and NaH2PO4/Na2HPO4. Variations in the spectra with pH and temperature at constant flow rate were used to determine the first ionization constant of uracil, K1a (uracil), and the first and second acid ionization constants of adenine, K1a (adenine) and K2a (adenine), at ionic strength I = 0.2 mol kg-1 and temperatures up to 200 °C. Time-dependent spectra, obtained by operating the cell as a stopped flow reactor, were used to examine the rate of thermal decomposition as a function of temperature and pH from 200 to 250 °C. Reaction pathways and rate constants were determined by singular value decomposition methods. Uracil and adenine decomposition occurred by one-step and two-step processes, respectively. The kinetic results in the NaH2PO4/Na2HPO4 buffer solution are in quantitative agreement with the less-extensive pioneering study by White (Nature 310, 430-432 (1984)), but differ from results in buffers that do not contain phosphate, suggesting that phosphate enhances the thermal stability of nucleic acid bases.

Balodis, Erik; Madekufamba, Melerin; Trevani, Liliana N.; Tremaine, Peter R.

2012-09-01

15

In-situ spectroelectrochemical evidences for the copolymerization of o-toluidine with diphenylamine-4-sulphonic acid by UV-visible spectroscopy  

NASA Astrophysics Data System (ADS)

In-situ spectroelectrochemical studies on the copolymerization of o-toluidine (OT) with diphenylamine-4-sulfonic acid (DPASA) were carried out on ITO electrode in 0.5 M H 2SO 4 for different feed ratios of OT and DPASA. The early stages of copolymerization of OT with DPASA have been identified through spectroelectrochemical techniques. The results revealed the formation of a head-to-tail dimer type of intermediate at the initial stages of copolymerization. This N-phenyl-paraphenylene diamine (PPD) type of intermediate was assigned to have a peak at 550 nm in UV-visible spectra and confirmed via derivative cyclic voltabsorptogram (DCVA). Constant potential electropolymerization results also supported the formation of intermediate with an absorption maximum at 550 nm.

Wen, Ten-Chin; Sivakumar, C.; Gopalan, A.

2002-01-01

16

In-situ spectroelectrochemical evidences for the copolymerization of o-toluidine with diphenylamine-4-sulphonic acid by UV-visible spectroscopy.  

PubMed

In-situ spectroelectrochemical studies on the copolymerization of o-toluidine (OT) with diphenylamine-4-sulfonic acid (DPASA) were carried out on ITO electrode in 0.5 M H2SO4 for different feed ratios of OT and DPASA. The early stages of copolymerization of OT with DPASA have been identified through spectroelectrochemical techniques. The results revealed the formation of a head-to-tail dimer type of intermediate at the initial stages of copolymerization. This N-phenyl-paraphenylene diamine (PPD) type of intermediate was assigned to have a peak at 550 nm in UV-visible spectra and confirmed via derivative cyclic voltabsorptogram (DCVA). Constant potential electropolymerization results also supported the formation of intermediate with an absorption maximum at 550 nm. PMID:11808643

Wen, Ten-Chin; Sivakumar, C; Gopalan, A

2002-01-01

17

Real-Time UV-Visible Spectroscopy Analysis of Purple Membrane-Polyacrylamide Film Formation Taking into Account Fano Line Shapes and Scattering  

PubMed Central

We theoretically and experimentally analyze the formation of thick Purple Membrane (PM) polyacrylamide (PA) films by means of optical spectroscopy by considering the absorption of bacteriorhodopsin and scattering. We have applied semiclassical quantum mechanical techniques for the calculation of absorption spectra by taking into account the Fano effects on the ground state of bacteriorhodopsin. A model of the formation of PM-polyacrylamide films has been proposed based on the growth of polymeric chains around purple membrane. Experimentally, the temporal evolution of the polymerization process of acrylamide has been studied as function of the pH solution, obtaining a good correspondence to the proposed model. Thus, due to the formation of intermediate bacteriorhodopsin-doped nanogel, by controlling the polymerization process, an alternative methodology for the synthesis of bacteriorhodopsin-doped nanogels can be provided. PMID:25329473

Gomariz, María; Blaya, Salvador; Acebal, Pablo; Carretero, Luis

2014-01-01

18

Real-time UV-visible spectroscopy analysis of purple membrane-polyacrylamide film formation taking into account Fano line shapes and scattering.  

PubMed

We theoretically and experimentally analyze the formation of thick Purple Membrane (PM) polyacrylamide (PA) films by means of optical spectroscopy by considering the absorption of bacteriorhodopsin and scattering. We have applied semiclassical quantum mechanical techniques for the calculation of absorption spectra by taking into account the Fano effects on the ground state of bacteriorhodopsin. A model of the formation of PM-polyacrylamide films has been proposed based on the growth of polymeric chains around purple membrane. Experimentally, the temporal evolution of the polymerization process of acrylamide has been studied as function of the pH solution, obtaining a good correspondence to the proposed model. Thus, due to the formation of intermediate bacteriorhodopsin-doped nanogel, by controlling the polymerization process, an alternative methodology for the synthesis of bacteriorhodopsin-doped nanogels can be provided. PMID:25329473

Gomariz, María; Blaya, Salvador; Acebal, Pablo; Carretero, Luis

2014-01-01

19

Ionization constants of aqueous amino acids at temperatures up to 250°C using hydrothermal pH indicators and UV-visible spectroscopy: Glycine, ?-alanine, and proline  

NASA Astrophysics Data System (ADS)

Ionization constants for several simple amino acids have been measured for the first time under hydrothermal conditions, using visible spectroscopy with a high-temperature, high-pressure flow cell and thermally stable colorimetric pH indicators. This method minimizes amino acid decomposition at high temperatures because the data can be collected rapidly with short equilibration times. The first ionization constant for proline and ?-alanine, K a,COOH, and the first and second ionization constants for glycine, K a,COOH and K a,NH4+, have been determined at temperatures as high as 250°C. Values for the standard partial molar heat capacity of ionization, ? rC po, COOH and ? rC po, NH4+, have been determined from the temperature dependence of ln (K a,COOH) and ln (K a,NH4+). The methodology has been validated by measuring the ionization constant of acetic acid up to 250°C, with results that agree with literature values obtained by potentiometric measurements to within the combined experimental uncertainty. We dedicate this paper to the memory of Dr. Donald Irish (1932-2002) of the University of Waterloo—friend and former supervisor of two of the authors (R.J.B. and P.R.T.).

Clarke, Rodney G. F.; Collins, Christopher M.; Roberts, Jenene C.; Trevani, Liliana N.; Bartholomew, Richard J.; Tremaine, Peter R.

2005-06-01

20

Quantitative phase spectroscopy  

PubMed Central

Quantitative phase spectroscopy is presented as a novel method of measuring the wavelength-dependent refractive index of microscopic volumes. Light from a broadband source is filtered to an ~5 nm bandwidth and rapidly tuned across the visible spectrum in 1 nm increments by an acousto-optic tunable filter (AOTF). Quantitative phase images of semitransparent samples are recovered at each wavelength using off-axis interferometry and are processed to recover relative and absolute dispersion measurements. We demonstrate the utility of this approach by (i) spectrally averaging phase images to reduce coherent noise, (ii) measuring absorptive and dispersive features in microspheres, and (iii) quantifying bulk hemoglobin concentrations by absolute refractive index measurements. Considerations of using low coherence illumination and the extension of spectral techniques in quantitative phase measurements are discussed. PMID:22567588

Rinehart, Matthew; Zhu, Yizheng; Wax, Adam

2012-01-01

21

Measurements of the rate constant of HOsub2 + NOsub2 + Nsub2 --> HOsub2NOsub2 + Nsub2 using near-infrared wavelength-modulation spectroscopy and UV-visible absorption spectroscopy  

NASA Technical Reports Server (NTRS)

Rate coefficients for the reaction HO(sub 2)+ NO(sub 2) + N(sub 2) --> HO(sub 2)NO(sub 2) + N(sub 2) (reaction 1) were measured using simultaneous near-IR and UV spectroscopy from 220 to 298 K and from 45 to 200 Torr.

Christensen, L. E.; Okumura, M.; Sander, S. P.; Friedl, R. R.; Miller, C. E.; Sloan, J. J.

2004-01-01

22

UV-visible spectroscopy as an alternative to liquid chromatography for determination of everolimus in surfactant-containing dissolution media: a useful approach based on solid-phase extraction.  

PubMed

High-throughput 96-well solid phase extraction (SPE) plate with C-18 reversed phase sorbent followed by UV-visible (UV-Vis) microplate reader was applied to the analysis of hydrophobic drugs in surfactant-containing dissolution media, which are often used to evaluate the in-vitro drug release of drug eluting stents (DES). Everolimus and dissolution medium containing Triton X-405 were selected as representatives, and the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedure was capable of removing interfering components (Triton X-405 and its impurities), allowing for an accurate automated spectrophotometric analysis to be performed. The proposed UV-Vis spectrophotometric method yielded equivalent results compared to a classical LC analysis method. Linear regression analysis indicated that both methods have the ability to obtain test results that are directly proportional to the concentration of analyte in the sample within the selected range of 1.0-10 ?g/ml for everolimus, with a coefficient of correlation (r(2)) value of >0.998 and standard deviation of the residuals (Syx) of <2%. The individual recoveries of everolimus ranged from 97 to 104% for the UV-Vis spectrophotometric method and from 98 to 102 for the HPLC method, respectively. The 95% CI of the mean recovery for the UV-Vis spectrophotometric method was 99-102% and for the HPLC method was 99-101%. No statistical difference was found between the mean recoveries of the methods (p=0.42). Hence the methods are free from interference due to Triton and other chemicals present in the dissolution medium. The variation in the amount of everolimus estimated by UV-Vis spectrophotometric and HPLC methods was ?3.5%, and the drug release profiles obtained by both methods were found to be equivalent by evaluation with two-one-sided t-test (two-tailed, p=0.62; mean of differences, 0.17; 95% CI, 0.62-0.96) and similarity factor f2 (f2 value, 87). The excellent conformity of the results makes UV-Vis spectrophotometer an ideal tool for analyzing the drugs in the media containing surfactants, after SPE. The 96-well SPE plates in combination with UV-Vis microplate reader provide a high throughput method for the determination of in-vitro drug release profile of DES. Switching from HPLC to UV-Vis spectrophotometer microplate reader assay reduces the solvent consumption and labor required for the sample analyses. This directly impacts the profitability of the laboratory. PMID:22726455

Kamberi, Marika; Tran, Thu-Ngoc

2012-11-01

23

Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control  

SciTech Connect

Ultraviolet–visible spectroscopy (UV–Visible) and time-resolved laser fluorescence spectroscopy (TRLFS) optical techniques can permit on-line analysis of actinide elements in a solvent extraction process in real time. These techniques have been used for measuring actinide speciation and concentration under laboratory conditions and are easily adaptable to multiple sampling geometries, such as dip probes, fiber-optic sample cells, and flow-through cell geometries. To fully exploit these techniques, researchers must determine the fundamental speciation of target actinides and the resulting influence on spectroscopic properties. Detection limits, process conditions, and speciation of key actinide components can be established and utilized in a range of areas, particularly those related to materials accountability and process control. Through this project, researchers will develop tools and spectroscopic techniques to evaluate solution extraction conditions and concentrations of U, Pu, and Cm in extraction processes, addressing areas of process control and materials accountability. The team will evaluate UVVisible and TRLFS for use in solvent extraction-based separations. Ongoing research is examining efficacy of UV-Visible spectroscopy to evaluate uranium and plutonium speciation under conditions found in the UREX process and using TRLFS to evaluate Cm speciation and concentration in the TALSPEAK process. A uranyl and plutonium nitrate UV–Visible spectroscopy study met with success, which supports the utility and continued exploration of spectroscopic methods for evaluation of actinide concentrations and solution conditions for other aspects of the UREX+ solvent extraction scheme. This project will ex examine U and Pu absorbance in TRUEX and TALSPEAK, perform detailed examination of Cm in TRUEX and TALSPEAK, study U laser fluorescence, and apply project data to contactors. The team will also determine peak ratios as a function of solution concentrations for the UV-Visible spectroscopy studies. The use of TRLFS to examine Cm and U will provide data to evaluate lifetime, peak location, and peak ratios (mainly for U). The bases for the spectroscopic techniques have been investigated, providing fundamental evidence for the application’s utility.

Czerwinski, Kenneth

2013-09-13

24

A complete vibrational study on a potential environmental toxicant agent, the 3,3?,4,4?-tetrachloroazobenzene combining the FTIR, FTRaman, UV-Visible and NMR spectroscopies with DFT calculations  

NASA Astrophysics Data System (ADS)

In this study 3,3?,4,4?-tetrachloroazobenzene (TCAB) was prepared and then characterized by infrared, Raman, multidimensional nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopies. The density functional theory (DFT) together with the 6-31G* and 6-311++G** basis sets were used to study the structures and vibrational properties of the two cis and trans isomers of TCAB. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels. A complete assignment of all the observed bands in the vibrational spectra of TCAB was performed combining the DFT calculations with the scaled quantum mechanical force field (SQMFF) methodology. The molecular electrostatic potentials, atomic charges, bond orders and frontier orbitals for the two isomers of TCAB were compared and analyzed. The comparison of the theoretical ultraviolet-visible spectrum with the corresponding experimental demonstrates a good concordance while the calculated 1H and 13C chemicals shifts are in good conformity with the corresponding experimental NMR spectra of TCAB in solution. The np®p* transitions for both forms were studied by natural bond orbital (NBO) while the topological properties were calculated by employing Bader’s Atoms in the Molecules (AIM) theory. This study shows that the cis and trans isomers exhibit different structural and vibrational properties and absorption bands.

Castillo, María V.; Pergomet, Jorgelina L.; Carnavale, Gustavo A.; Davies, Lilian; Zinczuk, Juan; Brandán, Silvia A.

2015-01-01

25

Development and Quantification of UV-Visible and Laser Spectroscopic Techniques for Materials Accountability and Process Control  

SciTech Connect

Ultraviolet-Visible Spectroscopy (UV-Visible) and Time Resolved Laser Fluorescence Spectroscopy (TRLFS) optical techniques can permit on-line, real-time analysis of the actinide elements in a solvent extraction process. UV-Visible and TRLFS techniques have been used for measuring the speciation and concentration of the actinides under laboratory conditions. These methods are easily adaptable to multiple sampling geometries, such as dip probes, fiber-optic sample cells, and flow-through cell geometries. To fully exploit these techniques for GNEP applications, the fundamental speciation of the target actinides and the resulting influence on 3 spectroscopic properties must be determined. Through this effort detection limits, process conditions, and speciation of key actinide components can be establish and utilized in a range of areas of interest to GNEP, especially in areas related to materials accountability and process control.

Ken Czerwinski; Phil Weck; Frederic Poineau

2010-12-29

26

A Quantitative Infrared Spectroscopy Experiment.  

ERIC Educational Resources Information Center

Although infrared spectroscopy is used primarily for qualitative identifications, it is possible to use it as a quantitative tool as well. The use of a standard curve to determine percent methanol in a 2,2,2-trifluoroethanol sample is described. Background information, experimental procedures, and results obtained are provided. (JN)

Krahling, Mark D.; Eliason, Robert

1985-01-01

27

UV/visible camera for the Clementine mission  

SciTech Connect

This article describes the Clementine UV/Visible (UV/Vis) multispectral camera, discusses design goals and preliminary estimates of on-orbit performance, and summarizes lessons learned in building and using the sensor. While the primary objective of the Clementine Program was to qualify a suite of 6 light-weight, low power imagers for future Department of Defense flights, the mission also has provided the first systematic mapping of the complete lunar surface in the visible and near-infrared spectral regions. The 410 g, 4.65 W UV/Vis camera uses a 384 x 288 frame-transfer silicon CCD FPA and operates at 6 user-selectable wavelength bands between 0.4 and 1.1 {micro}m. It has yielded lunar imagery and mineralogy data with up to 120 in spatial resolution (band dependent) at 400 km periselene along a 39 km cross-track swath.

Kordas, J.F.; Lewis, I.T.; Priest, R.E. [and others

1995-04-01

28

Cloud identification in the Canadian High Arctic using the UV-visible colour index  

NASA Astrophysics Data System (ADS)

In UV-visible spectroscopy, Rayleigh and Mie scattering contribute to the broadband extinction seen in spectra of scattered sunlight. The relative intensity of these two components of scattering is highly dependent on the cloud condition of the sky. The colour index, defined as the ratio of light intensities at different wavelengths, typically 350 nm and 550 nm, provides a means of determining the cloud conditions. A UV-visible triple-grating spectrometer, the UT-GBS (University of Toronto Ground-Based Spectrometer), was installed at the Polar Environment Atmospheric Research Laboratory (PEARL), at Eureka in the Canadian High Arctic (86.4°W, 80.1°N) in 1999. Since then, the instrument has made daily measurements during spring from 1999-2009, and year-round, with the exception of polar night, from 2010-2013. The UT-GBS measures vertical column densities of ozone, NO2, and BrO, as well as slant column densities of enhanced OClO, by using the Differential Optical Absorption Spectroscopy (DOAS) technique. We use the colour index data from the UT-GBS to distinguish polar stratospheric clouds and tropospheric clouds. The UV-visible measurements are supplemented by vertically resolved lidar and radar cloud data products. The CANDAC (Canadian Network for the Detection of Atmospheric Change) Rayleigh-Mie-Raman Lidar (CRL) and the Millimetre Cloud Radar (MMCR) are located at the Zero Altitude PEARL Auxiliary Laboratory (0PAL), which is about 15 km away from PEARL. The CRL uses ultra-short pulses of light from two lasers, operating at ultraviolet (355 nm) and visible (532 nm) wavelengths. The CRL measures the vertical distribution of aerosols, temperature, and water vapour in the troposphere and lower stratosphere. The zenith-pointing MMCR measures equivalent radar reflectivity, Doppler velocity, spectral width, and Doppler spectra, from which information about cloud heights, thicknesses, internal structure and vertical motions can be determined. Polar stratospheric cloud (PSC) events have been observed during spring by the UT-GBS and the CRL; these will be discussed in the context of the location of the polar vortex relative to Eureka, stratospheric temperatures, and stratospheric ozone loss events. In addition to detecting PSCs, the colour index can be used for the detection of tropospheric clouds. The UT-GBS cloud index results are in good agreement with data from the MMCR. Thus the cloud index can be useful for assessing the quality of DOAS retrievals, which can be greatly affected by tropospheric clouds.

Zhao, Xiaoyi; Adams, Cristen; Strong, Kimberly; Duck, Thomas; Perro, Chris; Hudak, David; Rodriguez, Peter

2014-05-01

29

UV / Visible / Near-Infrared Reflectance Models for the Rapid and Non-Destructive Prediction and Classification of Cotton Color and Physical Indices  

Technology Transfer Automated Retrieval System (TEKTRAN)

High volume instrumentation (HVI), utilized in the cotton industry to determine the qualities and classifications of cotton fibers, is time consuming, and prone to day-to-day and location-to-location variations. UV / visible / NIR spectroscopy, a rapid and easy sampling technique, was investigated a...

30

Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer  

SciTech Connect

UV-Visible spectrometer is used to record emission from magnesium and titanium metal plates during laser welding processing. Geometrically corrected Czerny-Turner configurations nearly eliminate defocusing problem. The Optikwerks software is used to find the optimum Czerny-Turner configuration and to choose optical elements such as grating types, mirrors focal length and diameter, and slit width. The design parameters of the uv-visible spectrometer in the wavelength range 200-1100 nm for monitoring laser material welding processing.

Genc, B.; Kacar, E.; Akman, E.; Demir, A. [University of Kocaeli, Laser Technologies Research and Application Center, Kocaeli (Turkey)

2007-04-23

31

QUANTITATIVE 15N NMR SPECTROSCOPY  

EPA Science Inventory

Line intensities in 15N NMR spectra are strongly influenced by spin-lattice and spin-spin relaxation times, relaxation mechanisms and experimental conditions. Special care has to be taken in using 15N spectra for quantitative purposes. Quantitative aspects are discussed for the 1...

32

In situ UV-visible assessment of extent of reduction during oxidation reactions on oxide catalysts  

E-print Network

In situ UV-visible assessment of extent of reduction during oxidation reactions on oxide catalysts as an Advance Article on the web 15th July 2003 The extent of reduction of active centers during oxidative to increase with increasing VOx domain size and propane/O2 ratio. Oxidative dehydrogenation (ODH) of alkanes

Bell, Alexis T.

33

Differentiating sources of soil water soluble organic matter by UV-visible spectral models  

Technology Transfer Automated Retrieval System (TEKTRAN)

UV-visible spectral models have been used to differentiate sources of dissolved organic matter in sea/fresh waters. Little information is available on using these models to characterize soil soluble organic matter. The objective of this study was to determine sources of soil soluble organic matter b...

34

Aprotic solvents effect on the UV-visible absorption spectra of bixin  

NASA Astrophysics Data System (ADS)

We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on ?max according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0 ? S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration.

Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin; Mouloungui, Zéphirin

2014-10-01

35

UV-visible transmittance of silicone-hydrogel contact lenses measured with a fiber optic spectrometer  

NASA Astrophysics Data System (ADS)

Protein deposition is one of the most frequent contaminants occurring on hydrophilic contact lenses and may modify the lens optical properties. The silicone-hydrogel contact lenses usually adsorb a lower amount of proteins than the conventional hydrogel ones. However it is important to study the influence of protein deposits on some silicone-hydrogel contact lenses properties, such as UV-Visible transmittance. In this study it is measured de UV-Visible properties of new and worn silicone-hydrogel contact lenses and the transmittance changes that can occur with wear are quantified. An optical fiber spectrometer has been used for measuring the transmittance of contact lenses. This spectrometer has the advantage that the lens can be positioned horizontally and the light beam passes through it perpendicularly. For the measurements, it was necessary to make a special cuvette to put inside the lens and keep it submerged in sterile saline solution. The contact lenses used were Biofinity®. They are manufactured by CooperVision with a material whose technical name is Comfilcon A. This material has not yet been analyzed for this purpose. Moreover, in this type of studies are commonly taken lenses of power -3.00D, however we have not limited to a single power value but we have extended the range to lower and higher values regarding to the standard power in order to see how this parameter affects.

Fuentes, R.; Fernández, E.; Pascual, I.; García, C.

2013-11-01

36

Aprotic solvents effect on the UV-visible absorption spectra of bixin.  

PubMed

We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on ?max according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0?S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration. PMID:24840486

Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin; Mouloungui, Zéphirin

2014-10-15

37

UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.  

PubMed

Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9?:?1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported. PMID:25451865

Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaci?owski, Konrad; Plavec, Janez; Magri, David C

2015-01-27

38

Journal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 505516  

E-print Network

­516 1. Introduction In the Earth's atmosphere, both in the far infrared and infrared regionsJournal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 505­516 www-4073(03)00174-2 #12;506 J. Boissoles et al. / Journal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 505

39

Standardization of UV-visible data in a food adulteration classification problem.  

PubMed

This study evaluates the performance of multivariate calibration transfer methods in a classification context. The spectral variation caused by some experimental conditions can worsen the performance of the initial multivariate classification model but this situation can be solved by implementing standardization methods such as Piecewise Direct Standardization (PDS). This study looks at the adulteration of culinary spices with banned dyes such as Sudan I, II, III and IV. The samples are characterised by their UV-visible spectra and Partial Least Squares-Discriminant Analysis (PLS-DA) is used to discriminate between unadulterated samples and samples adulterated with any of the four Sudan dyes. Two different datasets that need to be standardised are presented. The standardization process yields positive classification results comparable to those obtained from the initial PLS-DA model, in which high classification performance was achieved. PMID:23442691

Di Anibal, Carolina V; Ruisánchez, Itziar; Fernández, Mailén; Forteza, Rafel; Cerdà, Victor; Pilar Callao, M

2012-10-15

40

Journal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 544  

E-print Network

Journal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 5­44 www Spectroscopie Mol�eculaire, Universit�e Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium i Laboratoire de Spectroscopy & Radiative Transfer 82 (2003) 5­44 calculation codes: high-resolution spectroscopic parameters

Chance, Kelly

41

UV\\/Visible Spectroscopy of Asteroid 762 Pulcova and its Newly-discovered Moon  

Microsoft Academic Search

We propose to acquire separte, comparative, and simultaneous spectra of asteroid 762 Pulcova and its satellite. We will compare our results with those we obtain[ed] in a program approved in cycle 9 for 45 Eugenia and its moon. We discovered both of these moons using ground-based adaptive optics - Eugenia in 1998, but Pulcova only in the last year. We

William Merline

2001-01-01

42

INTERACTIONS OF METHYL ORANGE WITH CYCLODEXTRIN/SODIUM-MONTMORILLONITE SYSTEMS PROBED BY UV-VISIBLE SPECTROSCOPY  

EPA Science Inventory

Clay mineral colloids play important roles in the adsorption of polar organic contaminants in the environment. Similarly, cyclodextrins (CD) can entrap poorly water-soluble organic compounds. A combination of CDs and clay minerals affords great opportunities to investigate simult...

43

Exploration of Thermochromic Materials Using Experimental and Theoretical Infrared and UV-Visible Spectroscopy  

ERIC Educational Resources Information Center

This laboratory was developed by undergraduate students in collaboration with the course instructor as part of a peer-developed and peer-led lab curriculum in a general chemistry course. The goal was to explore the hypothesis that crystal violet lactone was responsible for the thermochromic properties of a sipping straw using a FT-IR for…

Costello, Kelsey; Doan, Kevin Thinh; Organtini, Kari Lynn; Wilson, John; Boyer, Morgan; Gibbs, Greglynn; Tribe, Lorena

2014-01-01

44

Spectroscopy of Fullerenes, Fulleranes and PAHs in the UV, Visible and Near Infrared Spectral Range  

NASA Astrophysics Data System (ADS)

The spectra of fullerenes C60 and C70, higher fullerenes C76, C78 and C84 and hydrogenated fullerenes (fulleranes) were studied in laboratory in the UV and in the visible spectral range and could be used for searching and recognizing these molecules in space. Furthermore, the radical cation spectra of all the mentioned fullerene series and also of a series of large and very large polycyclic aromatic hydrocarbons (PAHs) were generated in the laboratory and studied in the near infrared spectral range.

Cataldo, F.; García-Hernández, D. A.; Manchado, A.; Iglesias-Groth, S.

2014-02-01

45

Infrared quantitative spectroscopy and planetary atmospheres  

NASA Astrophysics Data System (ADS)

Optical measurements of atmospheric minor constituents are carried out using spectrometers working in the UV-visible, infrared and microwave spectral ranges. In all cases the quality of the analysis and of the interpretation of the atmospheric spectra requires the best possible knowledge of the molecular parameters of the species of interest. To illustrate this point we will concentrate on recent laboratory studies of nitric acid, chlorine nitrate and formaldehyde. Nitric acid is one of the important minor constituent of the terrestrial atmosphere. Using new and accurate experimental results concerning the spectroscopic properties of the H14NO3 and H15NO3 molecules, as well as improved theoretical methods (Perrin et al., 2004), it has been possible to generate an improved set of line parameters for these molecules in the 11.2 ?m spectral region. These line parameters were used to detect for the first time the H15NO3 molecule in the atmosphere analyzing atmospheric spectra recorded by the MIPAS experiment. The retrievals of chlorine nitrate profiles are usually performed using absorption cross sections (Birk and Wagner, 2003). Following a high resolution analysis of the ?3 and ?4bands of this species in the 12.8 ?m region wepropose, as a possibility, to use line by line calculation simulating its ?4Q-branch for the atmospheric temperature and pressure ranges. For the measurement of atmospheric formaldehyde concentrations, mid-infrared and ultraviolet absorptions are both used by ground, air or satellite instruments. It is then of the utmost importance to have consistent spectral parameters in these various spectral domains. Consequently the aim of the study performed at LISA (Gratien et al., 2007) was to intercalibrate formaldehyde spectra in the infrared and ultraviolet regions acquiring simultaneously UV and IR spectra using a common optical cell. The results of the work will be presented. Also high resolution infrared data derived from Perrin et al., 2003 have been used to determine vertical distributions from the upper troposphere to the stratopause using the high spectral resolution measurements of MIPAS (Steck et al., 2008). References: M. Birk, G. Wagner, J. Quant. Spectros. Radiat.Transfer, 82, 443, 2003. G. Brizzi, M. Carlotti, J.-M. Flaud, A. Perrin and M. Ridolfi, Geophys. Res. Lett., 34, L03802, 2006. A. Gratien, B. Picquet-Varrault, J. Orphal, E. Perraudin, J.-F. Doussin and J.-M. Flaud, J. Geophys. Res., 112, D05305, 2007. A. Perrin, F. Keller and J.-M. Flaud, J. Mol. Spectrosc., 221, 192, 2003. A. Perrin, J. Orphal, J.-M. Flaud, S. Klee, G. Mellau, H. Mader, D. Walbrodt and M. Winnewisser, J. Mol. Spectrosc, 228, 375, 2004. T. Steck, N. Glatthor, T. von Clarmann, H. Fischer, J. M. Flaud, B. Funke, U. Grabowski, M. Hopfner, S. Kellmann, A. Linden, A. Perrin, and G. P. Stiller, Atm. Chem. Phys., 8, 463, 2008.

Flaud, J.-M.

2009-04-01

46

CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: QA TESTS, QUANTITATION AND SPECTROSCOPY  

EPA Science Inventory

Confocal Microscopy System Performance: QA tests, Quantitation and Spectroscopy. Robert M. Zucker 1 and Jeremy M. Lerner 2, 1Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research Development, U.S. Environmen...

47

Quantitation of Auger and X-ray photoelectron spectroscopies  

SciTech Connect

Surface analysis using electron spectroscopies is now a well-established and continuously expanding area. With appropriate data treatment procedures, both Auger electron spectroscopy (AES, not to be confused with atomic expression spectroscopy) and X-ray photoelectron spectroscopy (XPS or ESCA) can routinely supply reliable qualitative and semiquantitative characterization of the near-surface region (top 1-100 /Angstrom/) of most solids. Complex sample matrix and instrumental parameters make quantitation of surface electron spectroscopies a real challenge. Kenneth W. Nebesny, Brian L. Mashloff, and Neal R. Armstrong of the University of Arizona describe approaches that make it possible to obtain reliable compositional information.

Nebesny, K.W.; Maschhoff, B.L.; Armstrong, N.R.

1989-04-01

48

Scientific objectives for UV/visible astrophysics investigations: a summary of responsesby the community (2012)  

NASA Astrophysics Data System (ADS)

Following several recommendations presented by the Astrophysics Decadal Survey 2010 centered around the need to define " a future ultraviolet-optical space capability", on 2012 May 25, NASA issued a Request for Information (RFI) seeking persuasive ultraviolet (UV) and visible wavelength astrophysics science investigations. The goal was to develop a cohesive and compelling set of science objectives that motivate and support the development of the next generation of ultraviolet/visible space astrophysics missions. Responses were due on 10 August 2012 when 34 submissions were received addressing a number of potential science drivers. A UV/visible Mission RFI Workshop was held on 2012 September 20 where each of these submissions was summarized and discussed in the context of each other. We present a scientific analysis of these submissions and presentations and the pursuant measurement capability needs, which could influence ultraviolet/visible technology development plans for the rest of this decade. We also describe the process and requirements leading to the inception of this community RFI, subsequent workshop and the expected evolution of these ideas and concepts for the remainder of this decade.

Scowen, Paul A.; Perez, Mario R.; Neff, Susan G.; Benford, Dominic J.

2014-02-01

49

Scientific Objectives for UV/Visible Astrophysics Investigations: A Summary of Responses by the Community (2012)  

NASA Technical Reports Server (NTRS)

Following several recommendations presented by the Astrophysics Decadal Survey 2010 centered around the need to define "a future ultraviolet-optical space capability," on 2012 May 25, NASA issued a Request for Information (RFI) seeking persuasive ultraviolet (UV) and visible wavelength astrophysics science investigations. The goal was to develop a cohesive and compelling set of science objectives that motivate and support the development of the next generation of ultraviolet/visible space astrophysics missions. Responses were due on 10 August 2012 when 34 submissions were received addressing a number of potential science drivers. A UV/visible Mission RFI Workshop was held on 2012 September 20 where each of these submissions was summarized and discussed in the context of each other. We present a scientific analysis of these submissions and presentations and the pursuant measurement capability needs, which could influence ultraviolet/visible technology development plans for the rest of this decade. We also describe the process and requirements leading to the inception of this community RFI, subsequent workshop and the expected evolution of these ideas and concepts for the remainder of this decade.

Scowen, Paul; Perez, Mario R.; Neff, Susan G.; Benford, Dominic J.

2012-01-01

50

Scientific Objectives for UV-Visible Astrophysics Investigations: A Summary of Responses by the Community (2012)  

NASA Technical Reports Server (NTRS)

Following several recommendations presented by the Astrophysics Decadal Survey 2010 centered around the need to define "a future ultraviolet-optical space capability," on 2012 May 25, NASA issued a Request for Information (RFI) seeking persuasive ultraviolet (UV) and visible wavelength astrophysics science investigations. The goal was to develop a cohesive and compelling set of science objectives that motivate and support the development of the next generation of ultraviolet/visible space astrophysics missions. Responses were due on 10 August 2012 when 34 submissions were received addressing a number of potential science drivers. A UV/visible Mission RFI Workshop was held on 2012 September 20 where each of these submissions was summarized and discussed in the context of each other. We present a scientific analysis of these submissions and presentations and the pursuant measurement capability needs, which could influence ultraviolet/visible technology development plans for the rest of this decade. We also describe the process and requirements leading to the inception of this community RFI, subsequent workshop and the expected evolution of these ideas and concepts for the remainder of this decade.

Scowen, Paul A.; Perez, Mario R.; Neff, Susan G.; Benford, Dominic J.

2014-01-01

51

UV-Visible Spectroscopic Method and Models for Assessment and Monitoring of Harmful Algal Blooms  

NASA Technical Reports Server (NTRS)

The development of an enhanced predictive and early warning capability for the occurrence and impact of harmful algal blooms (HABs) would be of great benefit to coastal communities. A critical issue for early detection and monitoring of HABs is the need to detect harmful algal species within a mixed-species phytoplankton assemblage. Possession of UV-absorbing compounds called mycosporine-like amino acids (MAAs) may be one factor that allows HAB species to out-compete their phytoplankton neighbors. Possession of MAAs, which we believe can be inferred from strong UV-absorption signals in phytoplankton absorption coefficients, can be used as a flag for potential HAB outbreak. The goal of this project was to develop a solar simulating UV-visible incubator to grow HAB dinoflagellates, to begin MAA analysis of samples collected on global cruises, and to carry out initial experiments on HAB dinoflagellate species in pure culture. Our scientific objectives are to quantify MAA production and spectral induction mechanisms in HAB species, to characterize spectral absorption of MAAs, and to define the ecological benefit of MAAs (i.e. photoprotection). Data collected on cruises to the global oceans will be used to parameterize phytoplankton absorption in the UV region, and this parameterization could be incorporated into existing models of seawater optical properties in the UV spectral region. Data collected in this project were used for graduate fellowship applications by Elizabeth Frame. She has been awarded an EPA STAR fellowship to continue the work initiated by this project.

Mitchell, B. Greg

2000-01-01

52

Investigation of convective transport in the tropical stratosphere using a lightweight uv-visible spectrometer sonde  

NASA Astrophysics Data System (ADS)

The occurrence of deep convective overshooting reaching altitudes up to 20 km is known for long above the tropical continents. They were shown recently shown to carry tropospheric chemical species, ice crystals, and possibly lightning NOx, in the lower stratosphere. For better investigating such process, a light UV-Visible spectrometer SAOZ balloon sonde, called mini-SAOZ, was developed on more advanced technology than the older instrument. The payload, weighting 9 kg, includes two spectrometers: a visible-near IR system for the measurement of O3, NO2, H2O, O4 and O2 and aerosol attenuation, and a UV system for BrO, OClO and CH2O). The mini-SAOZ sonde has been tested and qualified in flight with the help of CNES In Kiruna in Northern Sweden in 2010 and 2011. The plan is to fly several times this sonde on small balloons of 1500 m3 in South East Brazil in February-March 2012, next or immediately above convective systems during a TRO-pico campaign dedicated to the study of stratospheric hydration by geyser like injection of ice crystals and more generally fast convective lofting of tropospheric air in the stratosphere across the tropopause. After a short description of the instrument, the presentation will show the first results of those flights.

Vicomte, M.; Pommereau, J.-P.

2012-04-01

53

Scientific Objectives for UV-Visible Astrophysics Investigations: A Summary of Responses by the Community (2012)  

NASA Technical Reports Server (NTRS)

Following several recommendations presented by the Astrophysics Decadal Survey 2010 centered around the need to define "a future ultraviolet-optical space capability," on 2012 May 25, NASA issued a Request for Information (RFI) seeking persuasive ultraviolet (UV) and visible wavelength astrophysics science investigations. The goal was to develop a cohesive and compelling set of science objectives that motivate and support the development of the next generation of ultraviolet/visible space astrophysics missions. Responses were due on 10 August 2012 when 34 submissions were received addressing a number of potential science drivers. A UV/visible Mission RFI Workshop was held on 2012 September 20 where each of these submissions was summarized and discussed in the context of each other. We present a scientific analysis of these submissions and presentations and the pursuant measurement capability needs, which could influence ultraviolet/visible technology development plans for the rest of this decade. We also describe the process and requirements leading to the inception of this community RFI, subsequent workshop and the expected evolution of these ideas and concepts for the remainder of this decade.

Scowen, Paul A.; Perez, Mario R.; Neff, Susan G.; Bedford, Dominic J.

2013-01-01

54

Multispectral EO/IR sensor model for evaluating UV, visible, SWIR, MWIR and LWIR system performance  

NASA Astrophysics Data System (ADS)

Next Generation EO/IR Sensors using Nanostructures are being developed for a variety of Defense Applications. In addition, large area IRFPA's are being developed on low cost substrates. In this paper, we will discuss the capabilities of a EO/IR Sensor Model to provide a robust means for comparing performance of infrared FPA's and Sensors that can operate in the visible and infrared spectral bands that coincide with the atmospheric windows - UV, Visible-NIR (0.4-1.8?), SWIR (2.0-2.5?), MWIR (3-5?), and LWIR (8-14?). The model will be able to predict sensor performance and also functions as an assessment tool for single-color and for multi-color imaging. The detector model can also characterize ZnO, Si, SiGe, InGaAs, InSb, HgCdTe and Nanostructure based Sensors. The model can predict performance by also placing the specific FPA into an optical system, evaluates system performance (NEI, NETD, MRTD, and SNR). This model has been used as a tool for predicting performance of state-of-the-art detector arrays and nanostructure arrays under development. Results of the analysis can be presented for various targets for each of the focal plane technologies for a variety of missions.

Sood, Ashok K.; Richwine, Robert; Puri, Yash R.; Dhar, Nibir K.; Polla, Dennis L.; Wijewarnasuriya, Priyalal S.

2009-05-01

55

Intercomparison of total ozone data from nimbus 7 TOMS, the Brewer UV spectrophotometer and SOAZ uv-visible spectrophotometer at high latitudes observatory, Sodankylae  

SciTech Connect

The use of visible spectroscopy makes it possible to measure stratospheric constituents when Solar Zenith Angle (SZA) is as large as 93[degree]. This fact allows the daily measurements of ozone and other species throughout the year at and beyond the latitudes of the polar circle. Because the visible spectroscopy is a new technique in ozone monitoring, it is useful to compare it with the classical uv spectroscopy. At Sodankylae the widely-used SAOZ uv/visible spectrophotometer (Systeme d'Analyse et d'Observations Zenithales) and the modern uv spectrophotometer Brewer have been measuring side by side since early 1990. This paper reports the first long-term intercomparison between the daily total ozone values measured by the SAOZ and the Brewer covering the period from February 1990 to June 1991. As a reference the intercomparison between the Brewer and TOMS (Total Ozone Mapping Spectrometer) instruments from May 1988 to December 1991 is also reported. 13 refs., 4 figs., 2 tabs.

Kyroe, E.

1993-04-09

56

Quantitative Optical Spectroscopy for Tissue Diagnosis  

Microsoft Academic Search

The interaction of light within tissue has been used to recognize disease since the mid-1800s. The recent developments of small light sources, detectors, and fiber optic probes provide opportunities to quantitatively measure these interactions, which yield information for diagnosis at the biochemical, structural, or (patho)physiological level within intact tissues. However, because of the strong scattering properties of tissues, the reemitted

Rebecca Richards-Kortum; Eva Sevick-Muraca

1996-01-01

57

Amateur Spectroscopy: From Qualitative to Quantitative Analysis  

NASA Astrophysics Data System (ADS)

Spectroscopy is a new field of study for the amateur. This type of explor- ation by an amateur is the result of the availability of several types of off-the-shelf spectrometers, which can be coupled to a CCD camera. For the most part, amateurs pursuing this area have done so more from a qualitative standpoint: stellar classification and identification of the more prominent emission and absorption lines in stars and gas clouds. However, a spectrum contains much more valuable information about the physics of the region under survey. My talk will describe my initial efforts in the use of synthetic spectroscopy and how it can be used to determine a variety of stellar para- meters such as temperature and abundances. The process involves the creation of stellar atmospheric models where a variety of variables can be altered and the resulting spectrum fitted to the actual spectrum obtained at the tele- scope to find the best fit.

Mais, D. E.

2002-05-01

58

Quantitative Auger electron spectroscopy of SiC  

Microsoft Academic Search

The article is devoted to quantitative Auger electron spectroscopy (AES) of silicon carbide (SiC). It compares the results obtained by various procedures applied to LVV and KLL Auger peaks of silicon (Si) for determining the Auger current. We have found that reliable results for the content of Si in SiC can be achieved by the method in which the Auger

R. Kosiba; J. Liday; G. Ecke; O. Ambacher; J. Breza; P. Vogrin?i?

2006-01-01

59

Journal of Quantitative Spectroscopy & Radiative Transfer 105 (2007) 164165  

E-print Network

Journal of Quantitative Spectroscopy & Radiative Transfer 105 (2007) 164­165 Book review Cloud Library''. The title of the book is ambitious, and one immediately wonders whether the topic of cloud optics can be covered comprehensively on just 276 pages. In fact, my impression is that the author

60

Investigation of ground state charge transfer complex between paracetamol and p-chloranil through DFT and UV-visible studies  

NASA Astrophysics Data System (ADS)

The present report deals with the theoretical investigation on ground state structure and charge transfer (CT) transitions in paracetamol (PA)/p-chloranil (CA) complex using Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) method. It is found that Cdbnd O bond length of p-chloranil increases on complexation with paracetamol along with considerable amount of charge transfer from PA to CA. TD-DFT calculations have been performed to analyse the observed UV-visible spectrum of PA-CA charge transferred complex. Interestingly, in addition to expected CT transition, a weak symmetry relieved ?-?* transition in the chloranil is also observed.

Shukla, Madhulata; Srivastava, Nitin; Saha, Satyen

2012-08-01

61

Preparation of TiO2/(TiO2-V2O5)/polypyrrole nanocomposites and a study on catalytic activities of the hybrid materials under UV/Visible light and in the dark  

NASA Astrophysics Data System (ADS)

Hybrid metal oxides/polymer nanocomposites, namely TiO2/(TiO2-V2O5)/polypyrrole (PPy), were synthesized via in situ polymerization. Structures of the products were characterized by SEM-EDX, XRD, and FTIR techniques. The light absorbance and band gap energy values of the materials were evaluated by UV/Visible spectroscopy. The catalytic activity of the materials was determined from a degradation of methylene blue. It was found that, regardless of the polymerization time, the absorbance of TiO2/(TiO2-V2O5)/PPy was greater than those of TiO2/PPy and the neat TiO2, respectively. This was in accordance with the decrease in the band gap energy of the materials. The catalytic activity of TiO2/(TiO2-V2O5) was also observed in the dark. After polymerization, the catalytic activity of nanocomposite under UV/Visible light and in the dark was compromised. The above effects are discussed in the light of the energy storage ability of V2O5 and capability of the polymer in acting as a binder for the system.

Piewnuan, C.; Wootthikanokkhan, J.; Ngaotrakanwiwat, P.; Meeyoo, V.; Chiarakorn, S.

2014-11-01

62

Quantitative polarized Raman spectroscopy in highly turbid bone tissue  

NASA Astrophysics Data System (ADS)

Polarized Raman spectroscopy allows measurement of molecular orientation and composition and is widely used in the study of polymer systems. Here, we extend the technique to the extraction of quantitative orientation information from bone tissue, which is optically thick and highly turbid. We discuss multiple scattering effects in tissue and show that repeated measurements using a series of objectives of differing numerical apertures can be employed to assess the contributions of sample turbidity and depth of field on polarized Raman measurements. A high numerical aperture objective minimizes the systematic errors introduced by multiple scattering. We test and validate the use of polarized Raman spectroscopy using wild-type and genetically modified (oim/oim model of osteogenesis imperfecta) murine bones. Mineral orientation distribution functions show that mineral crystallites are not as well aligned (p<0.05) in oim/oim bones (28+/-3 deg) compared to wild-type bones (22+/-3 deg), in agreement with small-angle X-ray scattering results. In wild-type mice, backbone carbonyl orientation is 76+/-2 deg and in oim/oim mice, it is 72+/-4 deg (p>0.05). We provide evidence that simultaneous quantitative measurements of mineral and collagen orientations on intact bone specimens are possible using polarized Raman spectroscopy.

Raghavan, Mekhala; Sahar, Nadder D.; Wilson, Robert H.; Mycek, Mary-Ann; Pleshko, Nancy; Kohn, David H.; Morris, Michael D.

2010-05-01

63

Track core size estimation in CR-39 track detector using atomic force microscope and UV-visible spectrophotometer  

NASA Astrophysics Data System (ADS)

The radial size of track cores in CR-39 plastics for several types of ions has been determined by two different methods. First, atomic force microscope observations were performed on the irradiated CR-39 subsequent to the slight chemical etchings. The track core radii for C, O, Ne and Xe ions evaluated from the intersections of the extrapolated lines, fitted to each growth curve of etch pit radius, were found to be in the range between 2.8 and 4.1 nm, independent of the ion species. Second, UV-visible spectra of the irradiated CR-39 were obtained at various fluences. Based on a track overlapping model, the track core radii are evaluated for H, He, C and O ions. Their core radii were almost proportional to the cube root of the stopping power. The results from the two different measurements are in good agreement with each other.

Yamauchi, T.; Mineyama, D.; Nakai, H.; Oda, K.; Yasuda, N.

2003-08-01

64

Synthesis and crystal structure of hydroxyacetophenone Schiff bases containing propargyl moiety: Solvent effects on UV-visible spectra  

NASA Astrophysics Data System (ADS)

Four tetradentate (N2O2) and tridentate (NO2) Schiff base compounds (L1-L4) with propargyl moiety were prepared by the condensation of 1-[2-hydroxy-4-(prop-2-yn-1-yloxy)phenyl]ethanone with various aliphatic amines. The newly synthesized compounds (L1-L4) were characterized on the basis of the results of elemental analysis, thermal analysis, FT-IR, 1H NMR spectroscopic studies and single crystal X-ray crystallography. The different bands observed in the electronic spectra of the compounds in various organic solvents have been assigned to the proper electronic transitions. The hydrogen bonding and tautomeric equilibria in both of solution and the solid state are explained. The solvatochromism of the synthesized compounds in different solvents in the UV-visible spectra are discussed.

Selvarani, V.; Annaraj, B.; Neelakantan, M. A.; Sundaramoorthy, S.; Velmurugan, D.

2012-06-01

65

Optimized quantitative magnetic resonance spectroscopy for clinical routine.  

PubMed

Several practical obstacles in data handling and evaluation complicate the use of quantitative localized magnetic resonance spectroscopy (qMRS) in clinical routine MR examinations. To overcome these obstacles, a clinically feasible MR pulse sequence protocol based on standard available MR pulse sequences for qMRS has been implemented along with newly added functionalities to the free software package jMRUI-v5.0 to make qMRS attractive for clinical routine. This enables (a) easy and fast DICOM data transfer from the MR console and the qMRS-computer, (b) visualization of combined MR spectroscopy and imaging, (c) creation and network transfer of spectroscopy reports in DICOM format, (d) integration of advanced water reference models for absolute quantification, and (e) setup of databases containing normal metabolite concentrations of healthy subjects. To demonstrate the work-flow of qMRS using these implementations, databases for normal metabolite concentration in different regions of brain tissue were created using spectroscopic data acquired in 55 normal subjects (age range 6-61 years) using 1.5T and 3T MR systems, and illustrated in one clinical case of typical brain tumor (primitive neuroectodermal tumor). The MR pulse sequence protocol and newly implemented software functionalities facilitate the incorporation of qMRS and reference to normal value metabolite concentration data in daily clinical routine. PMID:22907544

Scheidegger, Olivier; Wingeier, Kevin; Stefan, Dan; Graveron-Demilly, Danielle; van Ormondt, Dirk; Wiest, Roland; Slotboom, Johannes

2013-07-01

66

Sacrificial hydrogen generation from aqueous triethanolamine with Eosin Y-sensitized Pt/TiO2 photocatalyst in UV, visible and solar light irradiation.  

PubMed

In this paper, we have studied Eosin Y-sensitized sacrificial hydrogen generation with triethanolamine as electron donor in UV, visible, and solar light irradiation. Aeroxide TiO2 was loaded with platinum metal via solar photo-deposition method to reduce the electron hole recombination process. Photocatalytic sacrificial hydrogen generation was influenced by several factors such as platinum loading (wt%) on TiO2, solution pH, Eosin Y to Pt/TiO2 mass ratio, triethanolamine concentration, and light (UV, visible and solar) intensities. Detailed reaction mechanisms in visible and solar light irradiation were established. Oxidation of triethanolamine and formaldehyde formation was correlated with hydrogen generation in both visible and solar lights. Hydrogen generation kinetics followed a Langmuir-type isotherm with reaction rate constant and adsorption constant of 6.77×10(-6)molmin(-1) and 14.45M(-1), respectively. Sacrificial hydrogen generation and charge recombination processes were studied as a function of light intensities. Apparent quantum yields (QYs) were compared for UV, visible, and solar light at four different light intensities. Highest QYs were attained at lower light intensity because of trivial charge recombination. At 30mWcm(-2) we achieved QYs of 10.82%, 12.23% and 11.33% in UV, visible and solar light respectively. PMID:25441927

Chowdhury, Pankaj; Gomaa, Hassan; Ray, Ajay K

2015-02-01

67

UV-visible microscope spectrophotometric polarization and dichroism with increased discrimination power in forensic analysis  

NASA Astrophysics Data System (ADS)

Microanalysis of transfer (Trace) evidence is the application of a microscope and microscopical techniques for the collection, observation, documentation, examination, identification, and discrimination of micrometer sized particles or domains. Microscope spectrophotometry is the union of microscopy and spectroscopy for microanalysis. Analytical microspectroscopy is the science of studying the emission, reflection, transmission, and absorption of electromagnetic radiation to determine the structure or chemical composition of microscopic-size materials. Microscope spectrophotometry instrument designs have evolved from monochromatic illumination which transmitted through the microscope and sample and then is detected by a photometer detector (photomultiplier tube) to systems in which broad-band (white light) illumination falls incident upon a sample followed by a non-scanning grating spectrometer equipped with a solid-state multi-element detector. Most of these small modern spectrometers are configured with either silicon based charged-couple device detectors (200-950 nm) or InGaAs based diode array detectors (850-2300 nm) with computerized data acquisition and signal processing being common. A focus of this research was to evaluate the performance characteristics of various modern forensic (UV-Vis) microscope photometer systems as well as review early model instrumental designs. An important focus of this research was to efficiently measure ultraviolet-visible spectra of microscopically small specimens for classification, differentiation, and possibly individualization. The first stage of the project consisted of the preparation of microscope slides containing neutral density filter reference materials, molecular fluorescence reference materials, and dichroic reference materials. Upon completion of these standard slide preparations analysis began with measurements in order to evaluate figures of merit for comparison of the instruments investigated. The figures of merit investigated included: 1) wavelength accuracy, 2) wavelength precision, 3) wavelength resolution stability, 4) photometric accuracy, 5) photometric precision, 6) photometric linearity, 7) photometric noise, and 8) short-term baseline stability. In addition, intrinsic instrument polarization effects were investigated to determine the impact of these properties on spectral interpretation and data quality. Finally, a set of recommendations were developed which describe instrument performance characteristics for microscope and spectrometer features and functions, and specific instrument parameters that must be controlled in order to acquire high quality data from an ultraviolet-visible forensic microscope spectrophotometer system for increased discrimination power.

Purcell, Dale Kevin

68

Chemical state and reactivity of supported palladium1. Characterization by XPS ((ESCA)) and UV-visible spectroscopy  

Microsoft Academic Search

After impregnating supports with palladium chloride and drying at 120°C, the palladium was present as the tetrachloropalladate on g- and delta-alumina and on titanium dioxide, but as an aquocomplex and palladium dichloride on silica. After hydrogen-reducing for six hours at 300°C, chlorine-containing palladium complexes remained on the surface; the chlorine-palladium ratio on alumina was 1:5; and it decreased in the

F. Bozon-Verduraz; J. Escard; A. Omar; B. Pontvianne

1978-01-01

69

Quantitative Cherenkov emission spectroscopy for tissue oxygenation assessment  

PubMed Central

Measurements of Cherenkov emission in tissue during radiation therapy are shown to enable estimation of hemoglobin oxygen saturation non-invasively, through spectral fitting of the spontaneous emissions from the treated tissue. Tissue oxygenation plays a critical role in the efficacy of radiation therapy to kill tumor tissue. Yet in-vivo measurement of this has remained elusive in routine use because of the complexity of oxygen measurement techniques. There is a spectrally broad emission of Cherenkov light that is induced during the time of irradiation, and as this travels through tissue from the point of the radiation deposition, the tissue absorption and scatter impart spectral changes. These changes can be quantified by diffuse spectral fitting of the signal. Thus Cherenkov emission spectroscopy is demonstrated for the first time quantitatively in vitro and qualitatively in vivo, and has potential for real-time online tracking of tissue oxygen during radiation therapy when fully characterized and developed. PMID:22418319

Axelsson, Johan; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

2012-01-01

70

Effect of local structure on the UV-visible absorption edges of molybdenum oxide clusters and supported molybdenum oxides  

SciTech Connect

Recent studies from a number of research groups have characterized the average particle sizes of domains of transition metal oxides or sulfides by means of an analysis of the optical bandgap energy, E{sub g}, determined from the position of the low energy rise in the material`s UV-visible spectrum. The characterization relies upon a relation between E{sub g} and the domain size of an insulator or semiconductor. As in the case of a particle-in-a-box, where the separation between energy levels decreases with increasing box size, the bandgap energy of a real system decreases as the domain size increases. An analytical function has been developed that models the bandgap behavior of particles in the size range from about 100 nm down to about 2 nm. Here, reanalysis of published spectra of molybdenum polyoxometalates has yielded a correlation between the optical bandgap energies and the average number of adjacent molybdenum cations in very small oxide clusters ({le}1 nm). 43 refs., 4 figs., 2 tabs.

NONE

1995-02-01

71

UV/Visible Aerosol Extinction Measurements performed by GOMOS onboard ENVISAT: results for the period August 2002 to March 2005.  

NASA Astrophysics Data System (ADS)

Launched in March 2002 the GOMOS Global Ozone Monitoring by Occultation of Stars instrument onboard the European Envisat satellite has already provided a wealth of information on the geographical and temporal distribution of several atmospheric species Vertical profiles for these species are numerically retrieved from measurements of starlight that is transmitted through the atmosphere at different tangent altitudes The actual spectrum at each tangent altitude is measured within the UV Visible wavelength range Typically within the useful range from 248 nm to 690 nm gas concentration profiles for O 3 NO 2 H 2 O neutral air and aerosol extinction profiles can be retrieved Although stars are relatively weak light sources the advantage of the star occultation lies in the fact that useful stars are available at all times during orbit As a consequence GOMOS has measured more than 300 000 occultations in the considered period from August 2002 to March 2005 In this work we present results for the aerosol extinction retrievals Using selection criteria for different occultation properties such as the star magnitude and the illumination conditions a subset of reliable occultations were picked Subsequently a spatial and temporal binning was performed and data were averaged The resulting climatology provides a good view on the spatial distribution and temporal evolution of aerosols in the stratosphere Special attention is given to the presence of PSCs in the Antarctic polar vortex and equatorial cirrus clouds First results on particle sizes

Vanhellemont, F.; Fussen, D.; Dodion, J.; Bingen, C.; Mateshvili, N.; Gomos Team

72

A Method for Quantitative Mapping of Thick Oil Spills Using Imaging Spectroscopy  

E-print Network

A Method for Quantitative Mapping of Thick Oil Spills Using Imaging Spectroscopy By Roger N. Clark (AVIRIS) Team, 2010, A method for quantitative mapping of thick oil spills using imaging spectroscopy: U ....................................................................................................................................................14 Figures 1. Image of oil emulsion from the Deepwater Horizon oil spill in the Gulf of Mexico off

Torgersen, Christian

73

Quantitative analysis of the dentin adhesive interface by Auger spectroscopy.  

PubMed

The ultimate success of a dentin adhesive bond is dependent in large part on specific conditions at the interface between the tooth and the adhesive. Most current dentin adhesive systems use some sort of pre-treatment to demineralize the first few microns of the dentin surface, leaving a meshwork of collagen into which the adhesive resin can penetrate, infiltrate, and polymerize. The general hypothesis tested in this experiment was that the penetration and distribution of adhesive resin into the demineralized zone are a function of the conditioner used as a pre-treatment for the adhesive application. Four commercially available adhesive systems were modified to incorporate hydroxyethylthiomethacrylate (HETMA), a sulfur-substituted, traceable analogue of 2-hydroxyethylmethacrylate (HEMA), thereby allowing for a qualitative measurement of the amount and distribution of monomer in the treated dentin substrate by energy-dispersive x-ray spectroscopy (EDS) and a quantitative measurement by Auger electron spectroscopy (AES). The dentin pre-treatments investigated were: (1) 10% citric acid/3% ferric chloride, (2) 10% maleic acid, (3) 2.5% nitric acid, and (4) an alcoholic solution of HEMA with a phosphorus acid ester. These pre-treatments were applied to freshly extracted teeth that had been sectioned to expose the dentin and ground to simulate the smeared layer. After the appropriate pre-treatment was applied, a 10% (v/v) solution of HETMA in acetone was applied to the surface, followed by the corresponding adhesive resin, which was then polymerized. The samples were then processed for observation by scanning transmission electron microscopy (STEM), AES, and STEM/EDS analysis. The results indicated significant differences in the ability of HETMA to penetrate the dentin surface conditioned by the four pretreatments investigated here. This study also demonstrated that AES and STEM/EDS could be used in a correlative fashion to determine the distribution of HETMA within or adjacent to the treated dentin surface. PMID:8708132

Eick, J D; Miller, R G; Robinson, S J; Bowles, C Q; Gutshall, P L; Chappelow, C C

1996-04-01

74

Laser Remote Measurements of atmospheric pollutants (Las-R-Map): UV-Visible Laser system description and data processing  

NASA Astrophysics Data System (ADS)

Laser radar more popularly known as LIDAR LIght Detection And Ranging is becoming one of the most powerful techniques for active remote sensing of the earth s atmosphere Around the globe several new lidar systems have been developed based on the scientific interest Particularly the DIfferential Absorption Lidar DIAL technique is only one which can provide the better accuracy of measuring atmospheric pollutants Using modern advanced techniques and instrumentation a mobile DIAL system called laser remote measurements of atmospheric pollutants hear after referred as Las-R-Map is designed at National Laser Centre NLC --Pretoria 25 r 45 prime S 28 r 17 prime E Las-R-Map is basically used for measuring atmospheric pollutants applying the principle of absorption by constituents The system designed primarily to focus on the following pollutant measurements such as SO 2 CH 4 CO 2 NO 2 and O 3 In future the system could be used to measure few particulate matter between 2 5 mu m and 10 mu m Benzene Hg 1 3-butadiene H 2 S HF and Volatile Organic Compounds VOC Las-R-map comprises of two different laser sources Alexandrite and CO 2 optical receiver data acquisition and signal processor It uses alexandrite laser in the UV-Visible region from 200 nm to 800 nm and CO 2 laser in the Far-IR region from 9 2 mu m to 10 8 mu m Such two different laser sources make feasibility for studying the wide range of atmospheric pollutants The present paper is focused on technical details

Sivakumar, V.; Wyk, H. V.

75

STRUCTURE OF PORPHYRIN TPPS4 AND ITS INTERACTION WITH METAL IONS AS ELUCIDATED BY 1H NMR AND UV-VISIBLE SPECTRA  

PubMed Central

Porphyrins are a group of tetrapyrrole pigments. Physical and chemical properties of porphyrins are often related to their compositions and structures. We conducted 1H solution NMR and UV-visible spectral analysis to characterize the structural feature of a water-soluble, synthetic porphyrin i.e. tetrakis (p-sulfonatophenyl) porphyrin, TPPS4, and its interaction with different metal ions in aqueous solutions. The results indicate that tetrapyrrole and tetraphenyl rings in TPPS4 molecule form a co-planar electron conjugation system; transition-metal ions show stronger binding capacity than alkali and alkali-earth metal ions; the relative stabilities of TPPS4-metal ion complexes can be well assessed by NMR and UV-visible spectral data. PMID:23564988

Song, Zhiyan; Adeyemo, Adegboye O.; Baker, Jannie; Traylor, Shakeya M.; Lightfoot, Marcia L.

2011-01-01

76

Automated affinity capture-release of biotin-containing conjugates using a lab-on-valve apparatus coupled to UV/visible and electrospray ionization mass spectrometry.  

PubMed

We report a new method for automated affinity capture and release of biotin-containing conjugates on immobilized streptavidin using a lab-on-valve (LOV) bead injection apparatus. The apparatus is also coupled to UV/visible and electrospray ionization mass spectrometry (ESI-MS) for monitoring the captured and released biotin-containing conjugates. Dissociation rate constants for release from streptavidin of two chromophore-tagged biotin conjugates were measured by UV/visible spectrometry and the dissociation was simultaneously monitored by ESI-MS. The LOV-ESI-MS instrument was also used for repetitive assays of lysosomal beta-galactosidase in human cell homogenates. Fast analysis in 4.5 min/full cycle and robust operation in 60 repetitive analyses are demonstrated that are promising for transfer of the LOV-ESI-MS technology into clinical practice. PMID:12349973

Ogata, Yuko; Scampavia, Louis; R?zicka, Jaromír; Scott, C Ronald; Gelb, Michael H; Turecek, Frantisek

2002-09-15

77

Qualitative and quantitative analysis of chlorinated solvents using Raman spectroscopy and machine learning.  

E-print Network

Qualitative and quantitative analysis of chlorinated solvents using Raman spectroscopy and machine is the identification of solvents into chlorinated or non-chlorinated. In this work we have used Raman spectroscopy. Keywords: Raman spectroscopy, hazardous materials, chlorinated solvents, non-chlorinated solvents

Madden, Michael

78

Determination of saffron (Crocus sativus L.) components in crude plant extract using high-performance liquid chromatography-UV-visible photodiode-array detection-mass spectrometry.  

PubMed

The determination of saffron components in crude plant extracts by high-performance liquid chromatography-UV-visible photodiode-array detection on-line with mass spectrometry is described. The method is shown to be suitable for the determination of picrocrocin, the glycosidic precursor of safranal, safranal and flavonoids; it is the technique of choice for the analysis of crocetin glycosides (crocins) carrying one up to five glucoses and differentiation of their trans and cis isomers. PMID:7757208

Tarantilis, P A; Tsoupras, G; Polissiou, M

1995-05-01

79

Determination of saffron ( Crocus sativus L.) components in crude plant extract using high-performance liquid chromatography-UV-visible photodiode-array detection-mass spectrometry  

Microsoft Academic Search

The determination of saffron components in crude plant extracts by high-performance liquid chromatography -UV-visible photodiode-array detection on-line with mass spectrometry is described. The method is shown to be suitable for the determination of picrocrocin, the glycosidic precursor of safranal, safranal and flavonoids; it is the technique of choice for the analysis of crocetin glycosides (crocins) carrying one up to five

Petros A. Tarantilis; George Tsoupras; Moschos Polissiou

1995-01-01

80

Quantitation of secondary structure in ATR infrared spectroscopy  

PubMed Central

Polarized attenuated total reflection infrared spectroscopy of aligned membranes provides essential information on the secondary structure content and orientation of the associated membrane proteins. Quantitation of the relative content of different secondary structures, however, requires allowance for geometric relations of the electric field components (E(x), E(y), E(z)) of the evanescent wave, and of the components of the infrared transition moments, in combining absorbances (A() and A( perpendicular)) measured with radiation polarized parallel with and perpendicular to, respectively, the plane of incidence. This has hitherto not been done. The appropriate combination for exact evaluation of relative integrated absorbances is A() + (2E(z)(2)/E(y)(2) - E(x)(2)/E(y)(2))A( perpendicular), where z is the axis of ordering that is normal to the membrane plane, and the x-axis lies in the membrane plane within the plane of incidence. This combination can take values in the range approximately from A() - 0.4A( perpendicular) to A() + 2.7A( perpendicular), depending on experimental conditions and the attenuated total reflection crystal used. With unpolarized radiation, this correction is not possible. Similar considerations apply to the dichroic ratios of multicomponent bands, which are also treated. PMID:10545362

Marsh, D

1999-01-01

81

GUEST EDITORIAL Coherent Multidimensional Optical Spectroscopy  

E-print Network

, Raman, and UV-visible spectroscopies, provide a one dimensional (1D) projection of the available to the picosecond, electronically off-resonant, coher- ent anti-Stokes Raman spectroscopy (CARS) measurements ofGUEST EDITORIAL Coherent Multidimensional Optical Spectroscopy Multidimensional optical techniques

Mukamel, Shaul

82

Quantitative Analysis by Isotopic Dilution Using Mass Spectroscopy: The Determination of Caffeine by GC-MS.  

ERIC Educational Resources Information Center

Describes a laboratory technique for quantitative analysis of caffeine by an isotopic dilution method for coupled gas chromatography-mass spectroscopy. Discusses caffeine analysis and experimental methodology. Lists sample caffeine concentrations found in common products. (MVL)

Hill, Devon W.; And Others

1988-01-01

83

Quantitative photopyroelectricout-of-phase spectroscopy of amorphous silicon thin films deposited on crystalline silicon  

E-print Network

Quantitative photopyroelectricout-of-phase spectroscopy of amorphous silicon thin films deposited on crystalline silicon CONSTANTINOSCHRISTOFIDES,ANDREASMANDELIS,AND ALBERTENGEL Phorouco~tsricutzcl Phororhertnal trans- mission and thermal-wave spectroscopic measurements of amorphous Si thin films, deposited

Mandelis, Andreas

84

Quantitative Determination of DNA-Ligand Binding Using Fluorescence Spectroscopy  

ERIC Educational Resources Information Center

The effective use of fluorescence spectroscopy for determining the binding of the intercalcating agent crhidium bromide to DNA is being described. The analysis used simple measurement techniques and hence can be easily adopted by the students for a better understanding.

Healy, Eamonn F.

2007-01-01

85

Quantitative biological Raman spectroscopy for non-invasive blood analysis  

E-print Network

The long term goal of this project is the measurement of clinically-relevant analytes in the blood tissue matrix of human subjects using near-infrared Raman spectroscopy, with the shorter term research directed towards ...

Shih, Wei-Chuan

2007-01-01

86

Quantitative Measurement of Trans-Fats by Infrared Spectroscopy  

ERIC Educational Resources Information Center

Trans-fat is a general term, which is mainly used to describe the various trans geometric isomers present in unsaturated fatty acids. Various techniques are now used for a quantitative measurement of the amount of trans-fats present in foods and cooking oil.

Walker, Edward B.; Davies, Don R.; Campbell, Mike

2007-01-01

87

Direct and quantitative photothermal absorption spectroscopy of individual particulates  

NASA Astrophysics Data System (ADS)

Photonic structures can exhibit significant absorption enhancement when an object's length scale is comparable to or smaller than the wavelength of light. This property has enabled photonic structures to be an integral component in many applications such as solar cells, light emitting diodes, and photothermal therapy. To characterize this enhancement at the single particulate level, conventional methods have consisted of indirect or qualitative approaches which are often limited to certain sample types. To overcome these limitations, we used a bilayer cantilever to directly and quantitatively measure the spectral absorption efficiency of a single silicon microwire in the visible wavelength range. We demonstrate an absorption enhancement on a per unit volume basis compared to a thin film, which shows good agreement with Mie theory calculations. This approach offers a quantitative approach for broadband absorption measurements on a wide range of photonic structures of different geometric and material compositions.

Tong, Jonathan K.; Hsu, Wei-Chun; Eon Han, Sang; Burg, Brian R.; Zheng, Ruiting; Shen, Sheng; Chen, Gang

2013-12-01

88

Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants  

NASA Astrophysics Data System (ADS)

Near-field infrared spectroscopy by elastic scattering of light from a probe tip resolves optical contrasts in materials at dramatically subwavelength scales across a broad energy range, with the demonstrated capacity for chemical identification at the nanoscale. However, current models of probe-sample near-field interactions still cannot provide a sufficiently quantitatively interpretation of measured near-field contrasts, especially in the case of materials supporting strong surface phonons. We present a model of near-field spectroscopy derived from basic principles and verified by finite-element simulations, demonstrating superb predictive agreement both with tunable quantum cascade laser near-field spectroscopy of SiO2 thin films and with newly presented nanoscale Fourier transform infrared (nanoFTIR) spectroscopy of crystalline SiC. We discuss the role of probe geometry, field retardation, and surface mode dispersion in shaping the measured near-field response. This treatment enables a route to quantitatively determine nanoresolved optical constants, as we demonstrate by inverting newly presented nanoFTIR spectra of an SiO2 thin film into the frequency dependent dielectric function of its mid-infrared optical phonon. Our formalism further enables tip-enhanced spectroscopy as a potent diagnostic tool for quantitative nanoscale spectroscopy.

McLeod, Alexander S.; Kelly, P.; Goldflam, M. D.; Gainsforth, Z.; Westphal, A. J.; Dominguez, Gerardo; Thiemens, Mark H.; Fogler, Michael M.; Basov, D. N.

2014-08-01

89

Machine learning methods for quantitative analysis of Raman spectroscopy data  

NASA Astrophysics Data System (ADS)

The automated identification and quantification of illicit materials using Raman spectroscopy is of significant importance for law enforcement agencies. This paper explores the use of Machine Learning (ML) methods in comparison with standard statistical regression techniques for developing automated identification methods. In this work, the ML task is broken into two sub-tasks, data reduction and prediction. In well-conditioned data, the number of samples should be much larger than the number of attributes per sample, to limit the degrees of freedom in predictive models. In this spectroscopy data, the opposite is normally true. Predictive models based on such data have a high number of degrees of freedom, which increases the risk of models over-fitting to the sample data and having poor predictive power. In the work described here, an approach to data reduction based on Genetic Algorithms is described. For the prediction sub-task, the objective is to estimate the concentration of a component in a mixture, based on its Raman spectrum and the known concentrations of previously seen mixtures. Here, Neural Networks and k-Nearest Neighbours are used for prediction. Preliminary results are presented for the problem of estimating the concentration of cocaine in solid mixtures, and compared with previously published results in which statistical analysis of the same dataset was performed. Finally, this paper demonstrates how more accurate results may be achieved by using an ensemble of prediction techniques.

Madden, Michael G.; Ryder, Alan G.

2003-03-01

90

Quantitative Raman spectroscopy for the analysis of carrot bioactives.  

PubMed

Rapid quantitative near-infrared Fourier transform Raman analyses of the key phytonutrients in carrots, polyacetylenes and carotenoids, are reported here for the first time. Solvent extracts of 31 carrot lines were analyzed for these phytonutrients by conventional methods, polyacetylenes by GC-FID and carotenoids by visible spectrophotometry. Carotenoid concentrations were 0-5586 ?g g(-1) dry weight (DW). Polyacetylene concentrations were 74-4846 ?g g(-1) DW, highest in wild carrots. The polyacetylenes were falcarinol, 6-1237 ?g g(-1) DW; falcarindiol, 42-3475 ?g g(-1) DW; and falcarindiol 3-acetate, 27-649 ?g g(-1) DW. Strong Raman bands for carotenoids gave good correlation to results by visible spectrophotometry. A chemometric model capable of quantitating carotenoids from Raman data was developed. A classification model for rapidly distinguishing carrots with high and low polyacetylene (limit of detection = 1400 ?g g(-1)) concentrations based on Raman spectral intensity in the region of 2250 cm(-1) was produced. PMID:23441972

Killeen, Daniel P; Sansom, Catherine E; Lill, Ross E; Eason, Jocelyn R; Gordon, Keith C; Perry, Nigel B

2013-03-20

91

Direct-potential-fit analysis of new infrared and UV/visible A 1?+-X 1?+ emission spectra of AgH and AgD  

NASA Astrophysics Data System (ADS)

New high-resolution infrared and UV/visible spectra of Ag107H, Ag109H, Ag107D, and Ag109D have been recorded with a Fourier transform spectrometer. The new line positions are combined with published microwave and older electronic A?+1-X?+1 data and used, first in a decoupled analysis of the X state alone, and then in a global multi-isotopologue analysis which yields comprehensive descriptions of both the X?+1 and A?+1 states of all four isotopologues of AgH. While the A state was long believed to be heavily perturbed, it is shown that its irregular spectrum merely reflects an unusual potential function shape. A direct fit of all data to appropriate radial Hamiltonians yields analytic potential-energy functions and Born-Oppenheimer breakdown radial functions for the ground X?+1 and A?+1 states.

Le Roy, Robert J.; Appadoo, Dominique R. T.; Anderson, Kevin; Shayesteh, Alireza; Gordon, Iouli E.; Bernath, Peter F.

2005-11-01

92

Quantitative Mueller matrix fluorescence spectroscopy for precancer detection.  

PubMed

Quantitative fluorescence spectroscopic Mueller matrix measurements from the connective tissue regions of human cervical tissue reveal intriguing fluorescence diattenuation and polarizance effects. Interestingly, the estimated fluorescence linear diattenuation and polarizance parameters were considerably reduced in the precancerous tissues as compared to the normal ones. These polarimetry effects of the autofluorescence were found to originate from anisotropically organized collagen molecular structures present in the connective tissues. Consequently, the reduction of the magnitude of these polarimetric parameters at higher grades of precancer was attributed to the loss of anisotropic organization of collagen, which was also confirmed by control experiments. These results indicate that fluorescence spectral diattenuation and polarizance parameters may serve as potentially useful diagnostic metrics. PMID:24562117

Jagtap, J; Chandel, S; Das, N; Soni, J; Chatterjee, S; Pradhan, A; Ghosh, N

2014-01-15

93

Quantitative Analysis of Nail Polish Remover Using Nuclear Magnetic Resonance Spectroscopy Revisited  

ERIC Educational Resources Information Center

Substantial modifications are presented for a previously described experiment using nuclear magnetic resonance (NMR) spectroscopy to quantitatively determine analytes in commercial nail polish remover. The revised experiment is intended for a second- or third-year laboratory course in analytical chemistry and can be conducted for larger laboratory…

Hoffmann, Markus M.; Caccamis, Joshua T.; Heitz, Mark P.; Schlecht, Kenneth D.

2008-01-01

94

Quantitative structural and textural assessment of laminar pyrocarbons through Raman spectroscopy, electron diffraction  

E-print Network

Quantitative structural and textural assessment of laminar pyrocarbons through Raman spectroscopy 6759, 45067 Orléans cedex 2, France Abstract In pyrocarbon materials, the width of the Raman D band be explained by the presence of sp3 -like line defects. Keywords: Pyrolytic carbons; Optical microscopy; Raman

Boyer, Edmond

95

Method for depth-resolved quantitation of optical properties in layered media using spatially modulated quantitative spectroscopy  

PubMed Central

We have demonstrated that spatially modulated quantitative spectroscopy (SMoQS) is capable of extracting absolute optical properties from homogeneous tissue simulating phantoms that span both the visible and near-infrared wavelength regimes. However, biological tissue, such as skin, is highly structured, presenting challenges to quantitative spectroscopic techniques based on homogeneous models. In order to more accurately address the challenges associated with skin, we present a method for depth-resolved optical property quantitation based on a two layer model. Layered Monte Carlo simulations and layered tissue simulating phantoms are used to determine the efficacy and accuracy of SMoQS to quantify layer specific optical properties of layered media. Initial results from both the simulation and experiment show that this empirical method is capable of determining top layer thickness within tens of microns across a physiological range for skin. Layer specific chromophore concentration can be determined to <±10% the actual values, on average, whereas bulk quantitation in either visible or near infrared spectroscopic regimes significantly underestimates the layer specific chromophore concentration and can be confounded by top layer thickness. PMID:21806282

Saager, Rolf B.; Truong, Alex; Cuccia, David J.; Durkin, Anthony J.

2011-01-01

96

Application of correlation constrained multivariate curve resolution alternating least-squares methods for determination of compounds of interest in biodiesel blends using NIR and UV-visible spectroscopic data.  

PubMed

This study describes two applications of a variant of the multivariate curve resolution alternating least squares (MCR-ALS) method with a correlation constraint. The first application describes the use of MCR-ALS for the determination of biodiesel concentrations in biodiesel blends using near infrared (NIR) spectroscopic data. In the second application, the proposed method allowed the determination of the synthetic antioxidant N,N'-Di-sec-butyl-p-phenylenediamine (PDA) present in biodiesel mixtures from different vegetable sources using UV-visible spectroscopy. Well established multivariate regression algorithm, partial least squares (PLS), were calculated for comparison of the quantification performance in the models developed in both applications. The correlation constraint has been adapted to handle the presence of batch-to-batch matrix effects due to ageing effects, which might occur when different groups of samples were used to build a calibration model in the first application. Different data set configurations and diverse modes of application of the correlation constraint are explored and guidelines are given to cope with different type of analytical problems, such as the correction of matrix effects among biodiesel samples, where MCR-ALS outperformed PLS reducing the relative error of prediction RE (%) from 9.82% to 4.85% in the first application, or the determination of minor compound with overlapped weak spectroscopic signals, where MCR-ALS gave higher (RE (%)=3.16%) for prediction of PDA compared to PLS (RE (%)=1.99%), but with the advantage of recovering the related pure spectral profile of analytes and interferences. The obtained results show the potential of the MCR-ALS method with correlation constraint to be adapted to diverse data set configurations and analytical problems related to the determination of biodiesel mixtures and added compounds therein. PMID:24840439

de Oliveira, Rodrigo Rocha; de Lima, Kássio Michell Gomes; Tauler, Romà; de Juan, Anna

2014-07-01

97

Quantitative reflectance spectroscopy of buddingtonite from the Cuprite mining district, Nevada  

NASA Technical Reports Server (NTRS)

Buddingtonite, an ammonium-bearing feldspar diagnostic of volcanic-hosted alteration, can be identified and, in some cases, quantitatively measured using short-wave infrared (SWIR) reflectance spectroscopy. In this study over 200 samples from Cuprite, Nevada, were evaluated by X ray diffraction, chemical analysis, scanning electron microscopy, and SWIR reflectance spectroscopy with the objective of developing a quantitative remote-sensing technique for rapid determination of the amount of ammonium or buddingtonite present, and its distribution across the site. Based upon the Hapke theory of radiative transfer from particulate surfaces, spectra from quantitative, physical mixtures were compared with computed mixture spectra. We hypothesized that the concentration of ammonium in each sample is related to the size and shape of the ammonium absorption bands and tested this hypothesis for samples of relatively pure buddingtonite. We found that the band depth of the 2.12-micron NH4 feature is linearly related to the NH4 concentration for the Cuprite buddingtonite, and that the relationship is approximately exponential for a larger range of NH4 concentrations. Associated minerals such as smectite and jarosite suppress the depth of the 2.12-micron NH4 absorption band. Quantitative reflectance spectroscopy is possible when the effects of these associated minerals are also considered.

Felzer, Benjamin; Hauff, Phoebe; Goetz, Alexander F. H.

1994-01-01

98

Detection and identification of intermediates in the reaction of L-serine with Escherichia coli tryptophan synthase via rapid-scanning ultraviolet-visible spectroscopy  

Microsoft Academic Search

Rapid-scanning stopped-flow (RSSF) UV-visible spectroscopy has been used to investigate the UV-visible absorption changes (300-550 nm) that occur in the spectrum of enzyme-bound pyridoxal 5'-phosphate during the reaction of L-serine with the alpha 2 beta 2 and beta 2 forms of Escherichia coli tryptophan synthase. In agreement with previous kinetic studies the reaction with alpha 2 beta 2 was found

William Frederick Drewe; Michael F. Dunn

1985-01-01

99

Electrical and optical spectroscopy for quantitative screening of hepatic steatosis in donor livers  

NASA Astrophysics Data System (ADS)

Macro-steatosis in deceased donor livers is increasingly prevalent and is associated with poor or non-function of the liver upon reperfusion. Current assessment of the extent of steatosis depends upon the macroscopic assessment of the liver by the surgeon and histological examination, if available. In this paper we demonstrate electrical and optical spectroscopy techniques which quantitatively characterize fatty infiltration in liver tissue. Optical spectroscopy showed a correlation coefficient of 0.85 in humans when referenced to clinical hematoxylin and eosin (H&E) sections in 20 human samples. With further development, an optical probe may provide a comprehensive measure of steatosis across the liver at the time of procurement.

McLaughlin, B. L.; Wells, A. C.; Virtue, S.; Vidal-Puig, A.; Wilkinson, T. D.; Watson, C. J. E.; Robertson, P. A.

2010-11-01

100

Quantitative influence of cholesterol on non-invasive blood glucose sensing studied with NIR spectroscopy  

NASA Astrophysics Data System (ADS)

Previous study results indicated that there is a certain influence of cholesterol on non-invasive blood glucose sensing studied with NIR spectroscopy. So, this talk aims to investigate quantitative influence of cholesterol through Partial Least Squares (PLS) modeling and Unary Linear Regression (ULR) analysis respectively. PLS modeling results indicate that glucose concentration increase with the increase of cholesterol concentration. ULR analysis results indicate that there is a positive correlation between the increment of glucose and the cholesterol concentration. And the quantitative relationship has been obtained.

Jiang, Jingying; Zhang, Lingling; Zhang, Kai; Xu, Kexin

2012-03-01

101

P-31 magnetic resonance spectroscopy and near-infrared spectroscopy provide unique quantitative data for evaluation of exercising muscles  

NASA Astrophysics Data System (ADS)

P-31 magnetic resonance spectroscopy (MRS) and near-infra spectroscopy (NIRS) have been used to characterize the dynamic aspects of human muscle contraction. P-31 MRS is a non- invasive method for measuring ATP, phosphocreatine (PCr), and pH in exercising muscles and thereby provides information regarding oxidative and glycolytic capacities for generating high energy phosphate compounds. NIRS evaluates kinetic changes in oxygen levels in muscles during exercise and recovery. These two methods provide unique quantitative data for studies of normal muscle contraction and for more complex investigations of muscle diseases. Non-invasive MRS and NIRS examinations are readily repeatable and yield important data for longitudinal patient evaluation and therapeutic management.

Park, Jane H.; Golwyn, Daniel; Olsen, Nancy J.; Newman, John H.; Powers, Alvin C.; Davis, Beverly C.; Rader, Kara; Chance, Britton

1994-09-01

102

Fourier transform infrared spectroscopy quantitative analysis of SF6 partial discharge decomposition components  

NASA Astrophysics Data System (ADS)

Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied.

Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin

2015-02-01

103

Fourier transform infrared spectroscopy quantitative analysis of SF6 partial discharge decomposition components.  

PubMed

Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied. PMID:25459612

Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin

2015-02-01

104

An efficient method-development strategy for quantitative chemical imaging using terahertz pulse spectroscopy  

Microsoft Academic Search

The purpose of our research was to investigate efficient procedures for generating multivariate prediction vectors for quantitative\\u000a chemical analysis of solid dosage forms using terahertz pulse imaging (TPI) reflection spectroscopy. A set of calibration\\u000a development and validation tablet samples was created following a ternary mixture of anhydrous theophylline, lactose monohydrate,\\u000a and microcrystalline cellulose (MCC). Spectral images of one side of

Robert P. Cogdill; Steven M. Short; Ryanne Forcht; Zhenqi Shi; Yaochun Shen; Philip F. Taday; Carl A. Anderson; James K. Drennen

2006-01-01

105

Protonation/deprotonation process of Emodin in aqueous solution and pKa determination: UV/Visible spectrophotometric titration and quantum/molecular mechanics calculations  

NASA Astrophysics Data System (ADS)

We combined theoretical and experimental studies to elucidate the important deprotonation process of Emodin in water. We used the UV/Visible spectrophotometric titration curves to obtain its pKa values, pKa1 = 8.0 ± 0.1 and pKa2 = 10.9 ± 0.2. Additionally, we obtained the pKa values of Emodin in the water-methanol mixture (1:3v/v). We give a new interpretation of the experimental data, obtaining apparent pKa1 = 6.2 ± 0.1, pKa2 = 8.3 ± 0.1 and pKa3 > 12.7. Performing quantum mechanics calculations for all possible deprotonation sites and tautomeric isomers of Emodin in vacuum and in water, we identified the sites of the first and second deprotonation. We calculated the standard deprotonation free energy of Emodin in water and the pKa1, using an explicit model of the solvent, with Free Energy Perturbation theory in Monte Carlo simulations obtaining, ?Gaq = 12.1 ± 1.4 kcal/mol and pKa1 = 8.7 ± 0.9. With the polarizable continuum model for the solvent, we obtained ?Gaq = 11.6 ± 1.0 kcal/mol and pKa1 = 8.3 ± 0.7. Both solvent models gave theoretical results in very good agreement with the experimental values.

da Cunha, Antonio R.; Duarte, Evandro L.; Lamy, M. Teresa; Coutinho, Kaline

2014-08-01

106

Quantitative analysis of polymorphic mixtures of ranitidine hydrochloride by Raman spectroscopy and principal components analysis.  

PubMed

Ranitidine hydrochloride exists as two polymorphs, forms I and II, both of which are used to manufacture commercial tablets. Raman spectroscopy can be used to differentiate the two forms but univariate methods of quantitative analysis of one polymorph as an impurity in the other lack sensitivity. We have applied principal components analysis (PCA) of Raman spectra to binary mixtures of the two polymorphs and to binary mixtures prepared by adding one polymorph to powdered tablets of the other. Based on absorption measurements of seven spectral regions, it was found that >97% of the spectral variation was accounted for by three principal components. Quantitative calibration models generated by multiple linear regression predicted a detection limit and quantitation limit for either forms I or II in mixtures of the two of 0.6 and 1.8%, respectively. This study demonstrates that PCA of Raman spectroscopic data provides a sensitive method for the quantitative analysis of polymorphic impurities of drugs in commercial tablets with a quantitation limit of less than 2%. PMID:12445565

Pratiwi, Destari; Fawcett, J Paul; Gordon, Keith C; Rades, Thomas

2002-11-01

107

Quantitative frequency-domain fluorescence spectroscopy in tissues and tissue-like media  

NASA Astrophysics Data System (ADS)

In the never-ending quest for improved medical technology at lower cost, modern near-infrared optical spectroscopy offers the possibility of inexpensive technology for quantitative and non-invasive diagnoses. Hemoglobin is the dominant chromophore in the 700-900 nm spectral region and as such it allows for the optical assessment of hemoglobin concentration and tissue oxygenation by absorption spectroscopy. However, there are many other important physiologically relevant compounds or physiological states that cannot be effectively sensed via optical methods because of poor optical contrast. In such cases, contrast enhancements are required. Fluorescence spectroscopy is an attractive component of optical tissue spectroscopy. Exogenous fluorophores, as well as some endogenous ones, may furnish the desperately needed sensitivity and specificity that is lacking in near-infrared optical tissue spectroscopy. The main focus of this thesis was to investigate the generation and propagation of fluorescence photons inside tissues and tissue-like media (i.e., scattering dominated media). The standard concepts of fluorescence spectroscopy have been incorporated into a diffusion-based picture that is sometimes referred to as photon migration. The novelty of this work lies in the successful quantitative recovery of fluorescence lifetimes, absolute fluorescence quantum yields, fluorophore concentrations, emission spectra, and both scattering and absorption coefficients at the emission wavelength from a tissue-like medium. All of these parameters are sensitive to the fluorophore local environment and hence are indicators of the tissue's physiological state. One application demonstrating the capabilities of frequency-domain lifetime spectroscopy in tissue-like media is a study of the binding of ethidium bromide to bovine leukocytes in fresh milk. Ethidium bromide is a fluorescent dye that is commonly used to label DNA, and hence visualize chromosomes in cells. The lifetime of ethidium bromide increases by an order of magnitude upon binding to DNA. In this thesis, I demonstrated that the fluorescence photon migration model is capable of accurately determining the somatic cell count (SCC) in a milk sample. Although meant as a demonstration of fluorescence tissue spectroscopy, this specific problem has important implications for the dairy industry's warfare against subclinical mastitis (i.e., mammary gland inflammation), since the SCC is often used as an indication of bovine infection.

Cerussi, Albert Edward

1999-09-01

108

Multiangle-multiwavelength UV/visible spectroscopy for the characterization of the joint property distribution of whole blood and its components  

NASA Astrophysics Data System (ADS)

The characterization of biological fluids for diagnostic purposes implies the estimation of the particle size distribution, the chemical composition, the shape distribution and the charge of the particles suspended in the fluid. These particle properties are defined as the joint particle property distribution. The shape distribution is especially important for the identification of healthy cells, sickle cells, viruses and bacteria. platelet viability can be determined from cell shape, discoid versus spheroid. Recent theoretical and simulations of the scattering behavior of particle dispersions using Mie and Rayleigh-Gans-Debye scattering models have demonstrated that complementary information on the joint property distribution is available from angular measurements of combined absorption and scattering spectra. A new multiangle- multiwavelength (MAMW) spectrophotometer was designed and developed using state-of-the-art fiber optic technology for the characterization of concentrated and dilute dispersion of biological fluids, primarily for whole blood and platelets. Miniature fiber optic UV/vis spectrometers were used to create a portable and robust characterization system; the spectrometer allows for the application of fields and easy adaptation for on-line analysis. This instrumentation was successfully tested for scattering measurement sensitivity and reproducibility and is capable of simultaneous absorption and scattering measurements at several angles and over a wide wavelength range. The MAMW spectrophotometer has been sued to analyze sizes of macromolecules and particle standards. Experimental results demonstrate that this technology can be used for the characterization of the joint property distribution of dilute dispersion of platelets, other biological particles and fluids.

Bacon, Christina P.; Garcia-Rubio, Luis H.

1998-04-01

109

Synthesis, crystal structure, and vibrational spectroscopic and UV-visible studies of Cs{sub 2}MnP{sub 2}O{sub 7}  

SciTech Connect

A new member of the A{sub 2}MP{sub 2}O{sub 7} diphosphate family, Cs{sub 2}MnP{sub 2}O{sub 7}, has been synthesized and structurally characterized. The crystal structure was determined by single crystal X-Ray diffraction. Cs{sub 2}MnP{sub 2}O{sub 7} crystallizes in the orthorhombic system, space group Pnma ( Music-Sharp-Sign 62), with the unit cell parameters a=16.3398(3), b=5.3872(1), c=9.8872(2) A, Z=4 and V=870.33(3) A{sup 3}. The structure parameters were refined to a final R{sub 1}/wR{sub 2}=0.0194/0.0441 for 1650 observed reflections. The 2D framework of Cs{sub 2}MnP{sub 2}O{sub 7} structure consists of P{sub 2}O{sub 7} and MnO{sub 5} units. The corner-shared MnO{sub 5} and P{sub 2}O{sub 7} units are alternately arranged along the b axis to form [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains. These chains are interconnected by an oxygen atom to form sheets parallel to the (b, c) plane. The cesium atoms are located between the sheets in 9- and 10-fold coordinated sites. The infrared and Raman vibrational spectra have been investigated. A factor group analysis leads to the determination of internal modes of (P{sub 2}O{sub 7}) groups. UV-visible spectrum consists of weak bands, between 340 and 700 nm, assigned to the forbidden d-d transitions of Mn{sup 2+} ion, and of a strong band around 250 nm, attributed to the O--Mn charge transfer. - Graphical abstract: Structure of Cs{sub 2}MnP{sub 2}O{sub 7}: The 2D structure of Cs{sub 2}MnP{sub 2}O{sub 7} is built from P{sub 2}O{sub 7} diphosphate groups and MnO{sub 5} square pyramids which share corners and form [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains along b axis. These chains are interconnected by an oxygen atom to form wavy (MnP{sub 2}O{sub 7}){sup 2-} sheets parallel to the (b, c) plane. The cesium ions are located between these sheets in the inter-layers space, in zigzag positions. Highlights: Black-Right-Pointing-Pointer A new diphosphate, Cs{sub 2}MnP{sub 2}O{sub 7}, has been synthesized and structurally characterized. Black-Right-Pointing-Pointer The structure consists of a 2D framework built up from (MnP{sub 2}O{sub 7}) sheets. Black-Right-Pointing-Pointer The sheets consist of [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains formed by P{sub 2}O{sub 7} units and MnO{sub 5} square pyramids. Black-Right-Pointing-Pointer A factor group analysis leads to the determination of internal modes of (P{sub 2}O{sub 7}) groups. Black-Right-Pointing-Pointer UV-visible spectrum consists bands assigned to d-d transitions of Mn{sup 2+} ion and to O--Mn CT.

Kaoua, Saida; Krimi, Saida [LPCMI, Faculte des Sciences Aien Chok, UH2C, Casablanca (Morocco)] [LPCMI, Faculte des Sciences Aien Chok, UH2C, Casablanca (Morocco); Pechev, Stanislav; Gravereau, Pierre; Chaminade, Jean-Pierre [CNRS, Universite de Bordeaux, ICMCB, 87, Avenue du Dr. A. Schweitzer, Pessac (France)] [CNRS, Universite de Bordeaux, ICMCB, 87, Avenue du Dr. A. Schweitzer, Pessac (France); Couzi, Michel [CNRS, Universite de Bordeaux, ISM, UMR 5255, F-33400 Talence (France)] [CNRS, Universite de Bordeaux, ISM, UMR 5255, F-33400 Talence (France); El Jazouli, Abdelaziz, E-mail: eljazouli_abdelaziz@yahoo.fr [LCMS, URAC 17, Faculte des Sciences Ben M'Sik, UH2MC, Casablanca (Morocco)

2013-02-15

110

Determination of Calcium in Cereal with Flame Atomic Absorption Spectroscopy: An Experiment for a Quantitative Methods of Analysis Course  

ERIC Educational Resources Information Center

An experiment for determination of calcium in cereal using two-increment standard addition method in conjunction with flame atomic absorption spectroscopy (FAAS) is demonstrated. The experiment is intended to introduce students to the principles of atomic absorption spectroscopy giving them hands on experience using quantitative methods of…

Bazzi, Ali; Kreuz, Bette; Fischer, Jeffrey

2004-01-01

111

Characterization of aquatic dissolved organic matter by asymmetrical flow field-flow fractionation coupled to UV-Visible diode array and excitation emission matrix fluorescence.  

PubMed

Flow field-flow fractionation (FlFFF) with on-line UV/Visible diode array detector (DAD) and excitation emission matrix (EEM) fluorescence detector has been developed for the characterization of optical properties of aquatic dissolved organic matter (DOM) collected in the Otonabee River (Ontario, Canada) and Athabasca River (Alberta, Canada). The molecular weight (MW) distribution of DOM was estimated using a series of organic macromolecules ranging from 479 to 66,000 Da. Both the number-average (M(n)) and weight-average (M(w)) molecular weights of Suwannee River fulvic acid (SRFA) and Suwannee River humic acid (SRHA) determined using these macromolecular standards were comparable to those obtained using polystyrenesulfonate (PSS) standards, suggesting that organic macromolecules can be used to estimate MW of natural organic colloids. The MW of eight river DOM samples determined by this method was found to have an M(n) range of 0.8-1.1 kDa, which agrees with available literature estimates. The FlFFF-DAD-EEM system provided insight into the MW components of river DOM including the optical properties by on-line absorbance and fluorescence measurement. A red-shift in emission and excitation wavelength maxima associated with lower spectral slope ratios (S(R)=S???????:S???????) was related to higher MW DOM. However, DOM of different origins at similar MW also showed significant difference in optical properties. A difference of 47 and 40 nm in excitation and emission peak C maxima was found. This supports the hypothesis that river DOM is not uniform in size and optical composition. PMID:21227433

Guéguen, Céline; Cuss, Chad W

2011-07-01

112

Stopped-flow rapid-scan Fourier transform infrared spectroscopy  

SciTech Connect

A stopped-flow rapid-mixing device interfaced with a rapid-scan FT-IR spectrometer and a diode-array UV-visible spectrophotometer permits the observation of reaction transient intermediates over a broad range of wavelengths at minimal cost. The system has been evaluated for both spectral regions with the use of two different chemical reaction systems. The presence of a transient intermediate is clearly indicated in one case. Unexpected reactivity was observed in the other case. This approach will allow the study of chemical reactions even when no spectral changes occur in the UV-visible region. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}

Dunn, B.C.; Eyring, E.M. [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 (United States)

1999-03-01

113

Quantitative analysis of peanut oil content in ternary blended edible oil using near infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Calibration models of quantitative analysis of peanut oil content in ternary blended edible oil by near infrared spectroscopy were built using partial least square (PLS) regression. A total of 92 samples blended with three kinds of pure oil in different proportion (V/V) were prepared. Near infrared diffuse reflectance spectra of the samples were collected over 4 000 cm -1-10 000 cm -1 spectral region with a FT-NIR spectrometer. A calibration model of prediction to the peanut oil content was established with PLS using the original spectra and validated with leave-one-out cross validation method. The correlation coefficient and the RMSEC of the model were 0.9926 and 2.91%, respectively. The result showed that near infrared spectroscopy could be an ideal tool for fast determination to the peanut oil content in blended edible oil.

Chen, Huacai; Liu, Fuli; Wang, Zhilan; Jin, Shangzhong

2008-03-01

114

Quantitative analysis of slurry sample by laser-induced breakdown spectroscopy.  

PubMed

Laser-induced breakdown spectroscopy (LIBS) has been employed for the analysis of slurry samples. Quantitative analysis of slurry samples is crucial and challenging. The problems associated with slurry samples include splashing, surface turbulence, and the difficulties of obtaining reproducible samples due to sedimentation. The LIBS analysis has achieved limited success due to inherent disadvantages when applied to slurry samples. In order to achieve improved measurement precision and accuracy, a spin-on-glass sampling method was evaluated. Five elements (Al, Ca, Fe, Ni, and Si) were examined in five slurry simulants containing varying amounts of each ion. Three calibration models were developed by using univariate calibration, multiple linear regression, and partial least square regression. LIBS analysis results obtained from the partial least square regression model were determined to be the best fit to results obtained from inductively coupled plasma optical emission spectroscopy analysis. PMID:21424178

Ayyalasomayajula, Krishna K; Dikshit, Vivek; Yueh, Fang Yu; Singh, Jagdish P; Smith, Laura T

2011-07-01

115

Quantitative mixture fraction measurements in combustion system via laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Laser induced breakdown spectroscopy (LIBS) technique has been applied to quantitative mixture fraction measurements in flames. The measured spectra of different mixtures of natural gas and air are used to obtain the calibration parameters for local elemental mass fraction measurements and hence calculate the mixture fraction. The results are compared with the mixture fraction calculations based on the ratios of the spectral lines of H/N elements, H/O elements and C/(N+O) and they show good agreement within the reaction zone of the flames. Some deviations are observed outside the reaction zone. The ability of LIBS technique as a tool for quantitative mixture fraction as well as elemental fraction measurements in reacting and non-reacting of turbulent flames is feasible.

Mansour, Mohy; Imam, Hisham; Elsayed, Khaled A.; Elbaz, A. M.; Abbass, Wafaa

2015-01-01

116

Accuracy improvement of quantitative analysis in laser-induced breakdown spectroscopy using modified wavelet transform.  

PubMed

A modified algorithm of background removal based on wavelet transform was developed for spectrum correction in laser-induced breakdown spectroscopy (LIBS). The optimal type of wavelet function, decomposition level and scaling factor ? were determined by the root-mean-square error of calibration (RMSEC) of the univariate regression model of the analysis element, which is considered as the optimization criteria. After background removal by this modified algorithm with RMSEC, the root-mean-square error of cross-validation (RMSECV) and the average relative error (ARE) criteria, the accuracy of quantitative analysis on chromium (Cr), vanadium (V), cuprum (Cu), and manganese (Mn) in the low alloy steel was all improved significantly. The results demonstrated that the algorithm developed is an effective pretreatment method in LIBS to significantly improve the accuracy in the quantitative analysis. PMID:24921726

Zou, X H; Guo, L B; Shen, M; Li, X Y; Hao, Z Q; Zeng, Q D; Lu, Y F; Wang, Z M; Zeng, X Y

2014-05-01

117

Quantification of skeletal muscle mitochondrial function by (31) P magnetic resonance spectroscopy techniques: a quantitative review.  

PubMed

Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive (31) P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle mitochondrial function and cellular pH homeostasis in vivo, but quantitative interpretation depends on understanding the underlying physiology. Here, by giving examples of the analysis of (31) P MRS recovery data, by some simple computational simulation, and by extensively comparing data from published studies using both (31) P MRS and invasive direct measurements of muscle O2 consumption in a common analytical framework, we consider what can be learnt quantitatively about mitochondrial metabolism in skeletal muscle using MRS-based methodology. We explore some technical and conceptual limitations of current methods, and point out some aspects of the physiology which are still incompletely understood. PMID:24773619

Kemp, G J; Ahmad, R E; Nicolay, K; Prompers, J J

2015-01-01

118

Quantitative emission from femtosecond microplasmas for laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

An ongoing study of the scaling of Laser-Induced Breakdown Spectroscopy (LIBS) to microjoule pulse energies is being conducted to quantify the LIBS process. The use of microplasmas for LIBS requires good understanding of the emission scaling in order to maximize the sensitivity of the LIBS technique at low energies. The quantitative scaling of emission of Al, Cu and Si microplasmas from 100 ?J down to 100 nJ is presented. The scaling of line emission from major and minor constituents in Al 5052 alloy is investigated and evaluated for analytical LIBS. Ablated crater volume scaling and emission efficiency for Si microplasmas are investigated.

Taschuk, M. T.; Kirkwood, S. E.; Tsui, Y. Y.; Fedosejevs, R.

2007-04-01

119

Comprehensive, quantitative bioprocess productivity monitoring using fluorescence EEM spectroscopy and chemometrics.  

PubMed

This study demonstrates the application of fluorescence excitation-emission matrix (EEM) spectroscopy to the quantitative predictive analysis of recombinant glycoprotein production cultured in a Chinese hamster ovary (CHO) cell fed-batch process. The method relies on the fact that EEM spectra of complex solutions are very sensitive to compositional change. As the cultivation progressed, changes in the emission properties of various key fluorophores (e.g., tyrosine, tryptophan, and the glycoprotein product) showed significant differences, and this was used to follow culture progress via multiple curve resolution alternating least squares (MCR-ALS). MCR-ALS clearly showed the increase in the unique dityrosine emission from the product glycoprotein as the process progressed, thus provided a qualitative tool for process monitoring. For the quantitative predictive modelling of process performance, the EEM data was first subjected to variable selection and then using the most informative variables, partial least-squares (PLS) regression was implemented for glycoprotein yield prediction. Accurate predictions with relative errors of between 2.3 and 4.6% were obtained for samples extracted from the 100 to 5000 L scale bioreactors. This study shows that the combination of EEM spectroscopy and chemometric methods of evaluation provides a convenient method for monitoring at-line or off-line the productivity of industrial fed-batch mammalian cell culture processes from the small to large scale. This method has applicability to the advancement of process consistency, early problem detection, and quality-by-design (QbD) practices. PMID:24504094

Li, Boyan; Shanahan, Michael; Calvet, Amandine; Leister, Kirk J; Ryder, Alan G

2014-04-01

120

Quantitative analyses of tartaric acid based on terahertz time domain spectroscopy  

NASA Astrophysics Data System (ADS)

Terahertz wave is the electromagnetic spectrum situated between microwave and infrared wave. Quantitative analysis based on terahertz spectroscopy is very important for the application of terahertz techniques. But how to realize it is still under study. L-tartaric acid is widely used as acidulant in beverage, and other food, such as soft drinks, wine, candy, bread and some colloidal sweetmeats. In this paper, terahertz time-domain spectroscopy is applied to quantify the tartaric acid. Two methods are employed to process the terahertz spectra of different samples with different content of tartaric acid. The first one is linear regression combining correlation analysis. The second is partial least square (PLS), in which the absorption spectra in the 0.8-1.4THz region are used to quantify the tartaric acid. To compare the performance of these two principles, the relative error of the two methods is analyzed. For this experiment, the first method does better than the second one. But the first method is suitable for the quantitative analysis of materials which has obvious terahertz absorption peaks, while for material which has no obvious terahertz absorption peaks, the second one is more appropriate.

Cao, Binghua; Fan, Mengbao

2010-10-01

121

The role of molecular packing on the UV-visible optical properties of [Re2Cl2(CO)64,5-(Me3Si)2pyridazine  

NASA Astrophysics Data System (ADS)

We report here on two stable polymorphs of the dinuclear complex [Re2(?-Cl)2(CO)6(?-4,5- (Me3Si)2pyridazine)]. The compound belongs to the recently reported class of dinuclear luminescent Re(I) complexes of general formula [Re2(?-Cl)2(CO)6(?-1,2-diazine)]. In the solid state, the complex exhibits a unique combination of unusual properties: (i) concomitant formation of two highly luminescent polymorphs, and single crystal-to-single-crystal conversion of one form into the other, (ii) remarkable differences in the absorption properties of the two polymorphs due to different redistribution of oscillator strength among the different excitons, and (iii) remarkable differences among the emission properties. In particular, a higher emission quantum yield was found in the solid state than in solution (measured to be 0.52 and 0.56 for the two polymorphs, almost one order of magnitude higher than that of the molecule in solution). Interest in luminescent materials able to efficiently emit in the solid state is continuously growing, because in most applications the dyes are used as solid films. Although rigid environments are expected to freeze rotovibrational relaxation pathways, luminescence efficiency often decreases in the solid state with respect to liquid solution due to concentration quenching, affecting both organic and organometallic emitters. However, an increasing number of molecular-based emitters exhibit enhanced solid state emission. Apart from the importance of bulky substituents in reducing concentration quenching effects, other intra- or inter-molecular phenomena have been invoked as well, such as conformational changes, ?-? stacking, hydrogen bonds, or Jaggregates, which cause rearrangements of the energy levels and population. In these two polymorphs the enhancement of the emission with respect to the solution is most likely due to the restricted rotation of the Me3Si groups in the crystals, providing an interesting example of aggregation-induced emission effect (AIE). To provide more insight into the optical properties of the two polymorphs, we present a combined computational and experimental study in the framework of crystal optics in the aim to explore the role of molecular packing on the UV-visible absorption properties of the two known polymorphs of [Re2(?-Cl)2(CO)6 (?-4,5-(Me3Si)2pyridazine)].

Spearman, P.; Tavazzi, S.; Silvestri, L.; Burini, A.; Borghesi, A.; Mercandelli, P.; Panigati, M.; D'Alfonso, G.; Sironi, A.; De Cola, L.

2012-06-01

122

Quantitative detection of astaxanthin and cantaxanthin in Atlantic salmon by resonance Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Two major carotenoids species found in salmonids muscle tissues are astaxanthin and cantaxanthin. They are taken up from fish food and are responsible for the attractive red-orange color of salmon filet. Since carotenoids are powerful antioxidants and biomarkers of nutrient consumption, they are thought to indicate fish health and resistance to diseases in fish farm environments. Therefore, a rapid, accurate, quantitative optical technique for measuring carotenoid content in salmon tissues is of economic interest. We demonstrate the possibility of using fast, selective, quantitative detection of astaxanthin and cantaxanthin in salmon muscle tissues, employing resonance Raman spectroscopy. Analyzing strong Raman signals originating from the carbon-carbon double bond stretch vibrations of the carotenoid molecules under blue laser excitation, we are able to characterize quantitatively the concentrations of carotenoids in salmon muscle tissue. To validate the technique, we compared Raman data with absorption measurements of carotenoid extracts in acetone. A close correspondence was observed in absorption spectra for tissue extract in acetone and a pure astaxanthin solution. Raman results show a linear dependence between Raman and absorption data. The proposed technique holds promise as a method of rapid screening of carotenoid levels in fish muscle tissues and may be attractive for the fish farm industry to assess the dietary status of salmon, risk for infective diseases, and product quality control.

Ermakov, Igor V.; Ermakova, Maia R.; Gellermann, Werner

2006-02-01

123

Feasibility of quantitative diffuse reflectance spectroscopy for targeted measurement of renal ischemia during laparoscopic partial nephrectomy  

NASA Astrophysics Data System (ADS)

Reduction of warm ischemia time during partial nephrectomy (PN) is critical to minimizing ischemic damage and improving postoperative kidney function, while maintaining tumor resection efficacy. Recently, methods for localizing the effects of warm ischemia to the region of the tumor via selective clamping of higher-order segmental artery branches have been shown to have superior outcomes compared with clamping the main renal artery. However, artery identification can prolong operative time and increase the blood loss and reduce the positive effects of selective ischemia. Quantitative diffuse reflectance spectroscopy (DRS) can provide a convenient, real-time means to aid in artery identification during laparoscopic PN. The feasibility of quantitative DRS for real-time longitudinal measurement of tissue perfusion and vascular oxygenation in laparoscopic nephrectomy was investigated in vivo in six Yorkshire swine kidneys (n=three animals). DRS allowed for rapid identification of ischemic areas after selective vessel occlusion. In addition, the rates of ischemia induction and recovery were compared for main renal artery versus tertiary segmental artery occlusion, and it was found that the tertiary segmental artery occlusion trends toward faster recovery after ischemia, which suggests a potential benefit of selective ischemia. Quantitative DRS could provide a convenient and fast tool for artery identification and evaluation of the depth, spatial extent, and duration of selective tissue ischemia in laparoscopic PN.

Goel, Utsav O.; Maddox, Michael M.; Elfer, Katherine N.; Dorsey, Philip J.; Wang, Mei; McCaslin, Ian Ross; Brown, J. Quincy; Lee, Benjamin R.

2014-10-01

124

Quantitative Determination of Ligand Densities on Nanomaterials by X-ray Photoelectron Spectroscopy.  

PubMed

X-ray photoelectron spectroscopy (XPS) is a nearly universal method for quantitative characterization of both organic and inorganic layers on surfaces. When applied to nanoparticles, the analysis is complicated by the strong curvature of the surface and by the fact that the electron attenuation length can be comparable to the diameter of the nanoparticles, making it necessary to explicitly include the shape of the nanoparticle to achieve quantitative analysis. We describe a combined experimental and computational analysis of XPS data for molecular ligands on gold nanoparticles. The analysis includes scattering in both Au core and organic shells and is valid even for nanoparticles having diameters comparable to the electron attenuation length (EAL). To test this model, we show experimentally how varying particle diameter from 1.3 to 6.3 nm leads to a change in the measured AC/AAu peak area ratio, changing by a factor of 15. By analyzing the data in a simple computational model, we demonstrate that ligand densities can be obtained, and, moreover, that the actual ligand densities for these nanoparticles are a constant value of 3.9 ± 0.2 molecules nm(-2). This model can be easily extended to a wide range of core-shell nanoparticles, providing a simple pathway to extend XPS quantitative analysis to a broader range of nanomaterials. PMID:25514372

Torelli, Marco D; Putans, Rebecca A; Tan, Yizheng; Lohse, Samuel E; Murphy, Catherine J; Hamers, Robert J

2015-01-28

125

Accuracy improvement of quantitative analysis by spatial confinement in laser-induced breakdown spectroscopy.  

PubMed

To improve the accuracy of quantitative analysis in laser-induced breakdown spectroscopy, the plasma produced by a Nd:YAG laser from steel targets was confined by a cavity. A number of elements with low concentrations, such as vanadium (V), chromium (Cr), and manganese (Mn), in the steel samples were investigated. After the optimization of the cavity dimension and laser fluence, significant enhancement factors of 4.2, 3.1, and 2.87 in the emission intensity of V, Cr, and Mn lines, respectively, were achieved at a laser fluence of 42.9 J/cm(2) using a hemispherical cavity (diameter: 5 mm). More importantly, the correlation coefficient of the V I 440.85/Fe I 438.35 nm was increased from 0.946 (without the cavity) to 0.981 (with the cavity); and similar results for Cr I 425.43/Fe I 425.08 nm and Mn I 476.64/Fe I 492.05 nm were also obtained. Therefore, it was demonstrated that the accuracy of quantitative analysis with low concentration elements in steel samples was improved, because the plasma became uniform with spatial confinement. The results of this study provide a new pathway for improving the accuracy of quantitative analysis of LIBS. PMID:23938689

Guo, L B; Hao, Z Q; Shen, M; Xiong, W; He, X N; Xie, Z Q; Gao, M; Li, X Y; Zeng, X Y; Lu, Y F

2013-07-29

126

Detection and quantitative analysis of ferrocyanide and ferricyanide: FY 93 Florida State University Raman spectroscopy report  

SciTech Connect

This report provides a summary of work to develop and investigate the feasibility of using Raman spectroscopy with tank waste materials. It contains Raman spectra from organics, such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetetraacteic acid (HEDTA), imino diacetic acid (IDA), kerosene, tributyl phosphate (TBP), acetone and butanol, anticipated to be present in tank wastes and spectra from T-107 real and BY-104 simulant materials. The results of investigating Raman for determining moisture content in tank materials are also presented. A description of software algorithms developed to process Raman spectra from a dispersive grating spectrometer system and an in initial design for a data base to support qualitative and quantitative application of remote Raman sensing with tank wastes.

Mann, C.K.; Vickers, T.J. [Florida State Univ., Tallahassee, FL (United States). Dept. of Chemistry

1994-10-11

127

Quantitative determination of the O({sup 3}P) density via visible cavity-enhanced spectroscopy  

SciTech Connect

A simple method has been developed to quantitatively measure the ground state oxygen atom, O({sup 3}P), density. The technique exploits cavity-enhanced spectroscopy to probe the relatively weak O({sup 1}D)(leftarrow)O({sup 3}P{sub 1}) transition near 636 nm. O({sup 3}P{sub 1}) densities of approximately 3.4x10{sup 14} at./cm{sup 3} were measured in an inductively coupled plasma produced within a high-finesse optical cavity, and a minimum detectable atom state density of 1.3x10{sup 12} at./cm{sup 3} was determined. The absorption profile yielded a translational temperature of 453 K. The technique can be readily extended to other atomic species.

Gupta, Manish; Owano, Thomas; Baer, Douglas; O'Keefe, Anthony [Los Gatos Research, 67 East Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

2006-12-11

128

Qualitative and quantitative assessment of water sorption in natural fibres using ATR-FTIR spectroscopy.  

PubMed

In the field of composite materials, natural fibres appear to be a viable replacement for glass fibres. However, in humid conditions, strong hydrophilic behaviour of such materials can lead to their structural modification. Then, understanding moisture sorption mechanisms in these materials is an important issue for their efficient use. In this work, the water sorption on three natural fibres (flax, hemp and sisal) was studied using Fourier transformed infrared spectroscopy. The spectral information allowed both qualitative and quantitative analyses of the moisture absorption mechanisms. The main chemical functions involved in the water sorption phenomenon were identified. The absolute water content of the fibres was also determined by using a partial least square regression (PLS-R) approach. Moreover, typical sorption isotherm curves described by Park model were fitted as well as water diffusion kinetics. These last applications confirmed the validity of the FTIR spectra based predictive models. PMID:24299761

Célino, Amandine; Gonçalves, Olivier; Jacquemin, Frédéric; Fréour, Sylvain

2014-01-30

129

Quantitative analysis of trace metal accumulation in teeth using laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

The technique of laser ablation is receiving increasing attention for applications in dentistry, specifically for the treatment of teeth (e.g. drilling of micro-holes and plaque removal). In the process of ablation a luminous micro-plasma is normally generated which may be exploited for elemental analysis. Here we report on quantitative Laser-Induced Breakdown Spectroscopy (LIBS) analysis to study the presence of trace minerals in teeth. A selection of teeth of different age groups has been investigated, ranging from the first teeth of infants, through the second teeth of children, to adults to trace the influence of environmental factors on the accumulation of a number of elements in teeth. We found a close link between elements detected in tooth fillings and toothpastes with those present in teeth.

Samek, O.; Beddows, D. C. S.; Telle, H. H.; Morris, G. W.; Liska, M.; Kaiser, J.

130

Terahertz time-domain spectroscopy and quantitative analysis of metal gluconates.  

PubMed

A series of metal gluconates (Na(+), K(+), Mg(2+), Ca(2+), Fe(2+), Cu(2+), and Zn(2+)) were investigated by terahertz (THz) time-domain spectroscopy. The absorption coefficients and refractive indices of the samples were obtained in the frequency range of 0.5-2.6 THz. The gluconates showed distinct THz characteristic fingerprints, and the dissimilarities reflect their different structures, hydrogen-bond networks, and molecular interactions. In addition, some common features were observed among these gluconates, and the similarities probably come from the similar carbohydrate anion group. The X-ray powder diffraction measurements of these metal gluconates were performed, and the copper(II) gluconate was found to be amorphous, corresponding to the monotonic increase feature in the THz absorption spectrum. The results suggest that THz spectroscopy is sensitive to molecular structure and physical form. Binary and ternary mixtures of different gluconates were quantitatively analyzed based on the Beer-Lambert law. A chemical map of a tablet containing calcium D-gluconate monohydrate and ?-lactose in the polyethylene host was obtained by THz imaging. The study shows that THz technology is a useful tool in pharmaceutical research and quality control applications. PMID:25506686

Li, Shaoxian; Yang, Jingqi; Zhao, Hongwei; Yang, Na; Jing, Dandan; Zhang, Jianbing; Li, Qingnuan; Han, Jiaguang

2015-01-01

131

An artificial neural network approach to laser-induced breakdown spectroscopy quantitative analysis  

NASA Astrophysics Data System (ADS)

The usual approach to laser-induced breakdown spectroscopy (LIBS) quantitative analysis is based on the use of calibration curves, suitably built using appropriate reference standards. More recently, statistical methods relying on the principles of artificial neural networks (ANN) are increasingly used. However, ANN analysis is often used as a ‘black box’ system and the peculiarities of the LIBS spectra are not exploited fully. An a priori exploration of the raw data contained in the LIBS spectra, carried out by a neural network to learn what are the significant areas of the spectrum to be used for a subsequent neural network delegated to the calibration, is able to throw light upon important information initially unknown, although already contained within the spectrum. This communication will demonstrate that an approach based on neural networks specially taylored for dealing with LIBS spectra would provide a viable, fast and robust method for LIBS quantitative analysis. This would allow the use of a relatively limited number of reference samples for the training of the network, with respect to the current approaches, and provide a fully automatizable approach for the analysis of a large number of samples.

D'Andrea, Eleonora; Pagnotta, Stefano; Grifoni, Emanuela; Lorenzetti, Giulia; Legnaioli, Stefano; Palleschi, Vincenzo; Lazzerini, Beatrice

2014-09-01

132

Usefulness of quantitative proton MR spectroscopy in the differentiation of benign and malignant meningioma.  

PubMed

This study was aimed to explore the value of quantitative proton MR spectroscopy (1H-MRS) in the differentiation of benign and malignant meningioma. 23 cases, including 19 benign (grade I) and 4 malignant (grade II-III) meningiomas, underwent single voxel 1H-MRS (TR/TE = 2000 ms/68, 136, 272 ms). T2 relaxation time of tissue water and choline were estimated by an exponential decay model. Choline concentration was calculated using tissue water as the internal reference, and corrected according to intra-voxel cystic/necrotic parts. Tissue water T2 of benign and malignant meningiomas were (105 +/- 41) ms and (151 +/- 42) ms, respectively. The difference was statistically significant (P = 0.033). While Choline T2 of benign and malignant meningiomas were (242 +/- 73) ms and (316 +/- 102) ms respectively, the difference was not significant (P = 0.105). Choline concentration was (2.86 +/- 0.86) mmol/ kg wet weight in benign meningiomas and (3.53 +/- 0.60) mmol/kg wet weight in malignant ones; after correction they increased to (2.98 +/- 0.93)mmol/kg wet weight and (4.58 +/- 1.22) mmol/kg wet weight, respectively, and the difference was significant (P = 0.019). In conclusion, quantitative 1H-MRS is useful for the differentiation of benign and malignant meningioma by T2 relaxation time and absolute choline concentration. PMID:22295694

Yue, Qiang; Isobe, Tomonori; Shibata, Yasushi; Kawamura, Hiraku; Anno, Izumi; Matsumura, Akira

2011-12-01

133

Quantitative Surface Chirality Detection with Sum Frequency Generation Vibrational Spectroscopy: Twin Polarization Angle Approach  

SciTech Connect

Here we report a novel twin polarization angle (TPA) approach in the quantitative chirality detection with the surface sum-frequency generation vibrational spectroscopy (SFG-VS). Generally, the achiral contribution dominates the surface SFG-VS signal, and the pure chiral signal is usually two or three orders of magnitude smaller. Therefore, it has been difficult to make quantitative detection and analysis of the chiral contributions to the surface SFG- VS signal. In the TPA method, by varying together the polarization angles of the incoming visible light and the sum frequency signal at fixed s or p polarization of the incoming infrared beam, the polarization dependent SFG signal can give not only direct signature of the chiral contribution in the total SFG-VS signal, but also the accurate measurement of the chiral and achiral components in the surface SFG signal. The general description of the TPA method is presented and the experiment test of the TPA approach is also presented for the SFG-VS from the S- and R-limonene chiral liquid surfaces. The most accurate degree of chiral excess values thus obtained for the 2878 cm?¹ spectral peak of the S- and R-limonene liquid surfaces are (23.7±0.4)% and ({25.4±1.3)%, respectively.

Wei, Feng; Xu, Yanyan; Guo, Yuan; Liu, Shi-lin; Wang, Hongfei

2009-12-27

134

Quantitative determination of element concentrations in industrial oxide materials by laser-induced breakdown spectroscopy.  

PubMed

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is employed for quantitative determination of oxide concentrations in multi-component materials. Industrial oxide materials from steel industry are laser ablated in air, and the optical plasma emission is collected by spectrometers and gated detectors. The temperature and electron number density of laser-induced plasma are determined from measured LIBS spectra. Emission lines of aluminium (Al), calcium (Ca), iron (Fe), manganese (Mn), magnesium (Mg), silicon (Si), titanium (Ti), and chromium (Cr) of low self-absorption are selected, and the concentration of oxides CaO, Al(2)O(3), MgO, SiO(2), FeO, MnO, TiO(2), and Cr(2)O(3) is calculated by CF-LIBS analysis. For all sample materials investigated, we find good match of calculated concentration values (C(CF)) with nominal concentration values (C(N)). The relative error in oxide concentration, e(r)?=?|C(CF)?-?C(N)|/C(N), decreases with increasing concentration and it is e(r)???100% for concentration C(N)???1 wt.%. The CF-LIBS results are stable against fluctuations of experimental parameters. The variation of laser pulse energy over a large range changes the error by less than 10% for major oxides (C(N)???10 wt.%). The results indicate that CF-LIBS method can be employed for fast and stable quantitative compositional analysis of multi-component materials. PMID:21523330

Praher, B; Rössler, R; Arenholz, E; Heitz, J; Pedarnig, J D

2011-07-01

135

A novel tridentate Schiff base dioxo-molybdenum(VI) complex: synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, ¹H NMR and ¹³C NMR spectra.  

PubMed

A new dioxo-molybdenum(VI) complex [MoO(2)(L)(H(2)O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H(2)L) and MoO(2)(acac)(2). The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the UV-visible, FTIR, (1)H NMR and (13)C NMR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TDDFT) method is used to calculate the electronic transitions of the complex. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental (1)H NMR spectra. However, the (13)C NMR shielding tensors computed at the B3LYP level, employing a combined basis set of DGDZVP for Mo and 6-31+G(2df,p) for other atoms, are in better agreement with experimental (13)C NMR spectra. The electronic transitions calculated at the B3LYP/DGDZVP level by using TD-DFT method is in accordance with the observed UV-visible spectrum of the compound. PMID:22613121

Saheb, Vahid; Sheikhshoaie, Iran; Stoeckli-Evans, Helen

2012-09-01

136

A new Schiff base compound N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone): synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, 1H NMR and 13C NMR spectra.  

PubMed

The Schiff base compound, N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone) (NDHA) is synthesized through the condensation of 2-hydroxylacetophenone and 2,2-dimethyl 1,3-amino propane in methanol at ambient temperature. The yellow crystalline precipitate is used for X-ray single-crystal determination and measuring Fourier transform infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP, PBEPBE and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the FTIR, (1)H NMR and (13)C NMR spectra of the compound. Time-dependent density functional theory (TDDFT) method is used to calculate the UV-visible spectrum of NDHA. Vibrational frequencies are determined experimentally and compared with those obtained theoretically. Vibrational assignments and analysis of the fundamental modes of the compound are also performed. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR and (13)C NMR chemical shifts calculated by all DFT methods are consistent with the experimental data. However, the NMR shielding tensors computed at the B3LYP/6-31+G(d,p) level of theory are in better agreement with experimental (1)H NMR and (13)C NMR spectra. The electronic absorption spectrum calculated at the B3LYP/6-31+G(d,p) level by using TD-DFT method is in accordance with the observed UV-visible spectrum of NDHA. In addition, some quantum descriptors of the molecule are calculated and conformational analysis is performed and the results were compared with the crystallographic data. PMID:21763188

Saheb, Vahid; Sheikhshoaie, Iran

2011-10-15

137

Tetra-2,3-pyrazinoporphyrazines with externally appended pyridine rings. 15. Effects of the pyridyl substituents and fused exocyclic rings on the UV-visible spectroscopic properties of Mg(II)-porphyrazines: a combined experimental and DFT/TDDFT study.  

PubMed

Two new Mg(II) porphyrazine macrocycles, the octakis(2-pyridyl)porphyrazinato-magnesium(II), [Py8PzMg(H2O)], and the tetrakis-[6,7-di(2-pyridyl)quinoxalino]porphyrazinato-magnesium(II), [Py8QxPzMg(H2O)], were prepared by Mg-template macrocyclization processes, and their general physicochemical properties were examined. The previously reported porphyrazine analog, the tetrakis-2,3-[5,6-di(2-pyridyl)-pyrazino]porphyrazinato-magnesium(II), [Py8PyzPzMg(H2O)], has been also considered in the present work. The UV-visible solution spectra in nonaqueous solvents of this triad of externally octapyridinated Mg(II) complexes exhibit the usual profile observed for phthalocyanine and porphyrazine macrocycles, with intense absorptions in the Soret (300-450 nm) and Q band (600-800 nm) regions. It is observed that the Q band maximum sensibly shifts toward the red with peak values at 635 ? 658 ? 759 nm along the series [Py8PzMg(H2O)], [Py8PyzPzMg(H2O)], and [Py8QxPzMg(H2O)], as the extension of the macrocycle ?-system increases. TDDFT calculations of the electronic absorption spectra were performed for the related water-free model compounds [Py8PzMg], [Py8PyzPzMg], and [Py8QxPzMg] to provide an interpretation of the UV-visible spectral changes occurring upon introduction of the pyrazine and quinoxaline rings at the periphery of the Pz macrocycle. To discriminate the electronic effects of the fused exocyclic rings from those of the appended 2-pyridyl rings, the UV-visible spectra of [PzMg] and [PyzPzMg] were also theoretically investigated. The theoretical results prove to agree very well with the experimental data, providing an accurate description of the UV-visible spectra. The observed spectral changes are interpreted on the basis of the electronic structure changes occurring along the series. PMID:25058801

Donzello, Maria Pia; De Mori, Giorgia; Viola, Elisa; Ercolani, Claudio; Ricciardi, Giampaolo; Rosa, Angela

2014-08-01

138

A Quantitative Near-Infrared Spectroscopy Study: A Decrease in Cerebral Hemoglobin Oxygenation in Alzheimer's Disease and Mild Cognitive Impairment  

ERIC Educational Resources Information Center

A newly developed quantitative near-infrared spectroscopy (NIRS) system was used to measure changes in cortical hemoglobin oxygenation during the Verbal Fluency Task in 32 healthy controls, 15 subjects with mild cognitive impairment (MCI), and 15 patients with Alzheimer's disease (AD). The amplitude of changes in the waveform, which was…

Arai, Heii; Takano, Maki; Miyakawa, Koichi; Ota, Tsuneyoshi; Takahashi, Tadashi; Asaka, Hirokazu; Kawaguchi, Tsuneaki

2006-01-01

139

An uncertainty budget for the determination of the purity of glyphosate by quantitative nuclear magnetic resonance (QNMR) spectroscopy  

Microsoft Academic Search

An uncertainty budget is presented for the results of measurements of purity of the agrochemical glyphosate using 1H and 31P quantitative nuclear magnetic resonance (QNMR) spectroscopy. The budget combines intralaboratory precision from repeated independent measurements of a batch, and other Type A and Type B effects. Consideration of correlation of uncertainties in ratios of mass determinations has been included. Expanded

TareqSaed Al-Deen; D. Brynn Hibbert; James M. Hook; Robert J. Wells

2004-01-01

140

Quantitative Optical Spectroscopy: A Robust Tool for Direct Measurement of Breast Cancer Vascular Oxygenation and Total Hemoglobin Content In vivo  

Microsoft Academic Search

We propose the use of a robust, biopsy needle-based, fiber- optic tool for routine clinical quantification of tumor oxygenation at the time of diagnostic biopsy for breast cancer. The purpose of this study was to show diffuse reflectance spectroscopy as a quantitative tool to measure oxygenation levels in the vascular compartment of breast cancers in vivo via an optical biopsy

J. Quincy Brown; Lee G. Wilke; Joseph Geradts; Stephanie A. Kennedy; Gregory M. Palmer; Nirmala Ramanujam

2009-01-01

141

Quantitative Fourier transform infrared spectroscopy of binary mixtures of fatty acid esters using partial least squares regression  

Microsoft Academic Search

This work describes a quantitative spectroscopic method for the analysis of binary mixtures of fatty acid esters using multivariate data models based upon Fourier Transform Infra Red (FT-IR) spectroscopy. Multivariate calibration of binary mixtures has been performed using Partial Least Squares regression (PLS), with two approaches being applied for fitting the inner relation namely a standard linear function and a

Emma S. Haines; Anthony D. Walmsley; Stephen J. Haswell

1997-01-01

142

MR of Hypoxic Encephalopathy in Children after Near Drowning: Correlation with Quantitative Proton MR Spectroscopy and Clinical Outcome  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Quantitative MR spectroscopy has a proved role in the investigation of hypoxia caused by near drowning. To date, no studies have addressed the MR imaging changes that may also accompany this condition. The purpose of this study was to describe the MR imaging findings in children with hypoxic encephalopathy caused by near drowning and to compare these

David J. Dubowitz; Stefan Bluml; Edgardo Arcinue; Rosalind B. Dietrich

143

Quantitative measurement of AMS and orange mixtures by terahertz time-domain spectroscopy  

NASA Astrophysics Data System (ADS)

Terahertz time domain spectroscopy (THz-TDS) is a new kind of nondestructive detection method, frequency of terahertz wave spans from a few tens of GHz to several THz, which is used to detect material because of its strong identification, it can supply rich vibration information caused by intermolecular and large intra-molecular. Ammonium sulfamate (AMS) is a kind of herbicide, it has special value for many woody plants, which can prevent annual weeds. The excess use of pesticide is a huge threaten for human health in recent years, thus the research on detection of pesticide has absolutely important meaning, in this paper, pure AMS and mixture samples of AMS and orange are measured using THz-TDS, and their absorption coefficient are calculated by the model, which is put forward based on Fresnel equation. We qualitatively analyze the absorption coefficient spectra of pure AMS, which is useful for us to identify the pesticide in agriculture products. Meanwhile, we measured 14 mixture samples of AMS and orange, the weight ratio of mixtures are from 0% to 59.9%. Nine samples are considered as calibration set and the other five samples are regarded as prediction set, to quantitatively analyze the concentration of AMS by the partial least squares (PLS), the result shows that the prediction error is less then 4.5%, in addition, the relationship of the average absorption and weight ratio are absolutely linear. The experiment demonstrates that THz-TDS is promising and efficient to quantitatively detect the component of mixtures, and it has important reference value for the detection of pesticide in agriculture food.

Wang, Qiang; Ma, Yehao; Wang, Xiaowei

2012-06-01

144

Quantitative elemental detection of size-segregated particles using laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

In order to simulate coal combustion and develop optimal and stable boiler control systems in real power plants, it is imperative to obtain the detailed information in coal combustion processes as well as to measure species contents in fly ash, which should be controlled and analyzed for enhancing boiler efficiency and reducing environmental pollution. The fly ash consists of oxides (SiO2, Al2O3, Fe2O3, CaO, and so on), unburned carbon, and other minor elements. Recently laser-induced breakdown spectroscopy (LIBS) technique has been applied to coal combustion and other industrial fields because of the fast response, high sensitivity, real-time and non-contact features. In these applications it is important to measure controlling factors without any sample preparation to maintain the real-time measurement feature. The relation between particle content and particle diameter is also one of the vital researches, because compositions of particles are dependent on their diameter. In this study, we have detected the contents of size-segregated particles using LIBS. Particles were classified by an Anderson cascade impactor and their contents were measured using the output of 1064 nm YAG laser, a spectrograph and an ICCD camera. The plasma conditions such as plasma temperature are dependent on the size of particles and these effects must be corrected to obtain quantitative information. The plasma temperature was corrected by the emission intensity ratio from the same atom. Using this correction method, the contents of particles can be measured quantitatively in fixed experimental parameters. This method was applied to coal and fly ash from a coal-fired burner to measure unburned carbon and other contents according to the particle diameter. The acquired results demonstrate that the LIBS technique is applicable to measure size-segregated particle contents in real time and this method is useful for the analysis of coal combustion and its control because of its sensitive and fast analysis features.

Wang, Zhen Zhen; Deguchi, Yoshihiro; Kuwahara, Masakazu; Taira, Takuya; Zhang, Xiao Bo; Yan, Jun Jie; Liu, Ji Ping; Watanabe, Hiroaki; Kurose, Ryoichi

2013-09-01

145

A calculation of backscattering factor database for quantitative analysis by Auger electron spectroscopy  

NASA Astrophysics Data System (ADS)

A systematic calculation of the backscattering factor in quantitative analysis by Auger electron spectroscopy has been performed for the primary electron beam of energy from the threshold energy of inner-shell ionization to 30 keV at the incident angle of 0°-89° and for principal Auger transition and Auger electrons emitted from over 28 pure elements at an emission angle of 0°-89° by using a Monte Carlo simulation method. The calculation employs a general definition of backscattering factor, Casnati's ionization cross section, up-to-date Monte Carlo model of electron scattering, and a large number of electron trajectories to ensure less statistical error. Both the configuration geometry of concentric hemispherical analyzer and the cylindrical mirror analyzer for Auger electron detection are considered in the calculation. The calculated backscattering factors are found to describe very well an experimental dependence of Auger electron intensity on primary energy and on incident angle for Si, Cu, Ag, and W in literature. The calculated numerical values of backscattering factor are stored in an open and online database at http://micro.ustc.edu.cn/BSFDataBase/BFAES.htm.

Zeng, R. G.; Ding, Z. J.; Li, Y. G.; Mao, S. F.

2008-12-01

146

Broadband reflectance spectroscopy for establishing a quantitative metric of vascular leak using the Miles assay  

NASA Astrophysics Data System (ADS)

Monitoring the physiological effects of biological mediators on vascular permeability is important for identifying potential targets for antivascular leak therapy. This therapy is relevant to treatments for pulmonary edema and other disorders. Current methods of quantifying vascular leak are in vitro and do not allow repeated measurement of the same animal. Using an in vivo diffuse reflectance optical method allows pharmacokinetic analysis of candidate antileak molecules. Here, vascular leak is assessed in mice and rats by using the Miles assay and introducing irritation both topically using mustard oil and intradermally using vascular endothelial growth factor (VEGF). The severity of the leak is assessed using broadband diffuse reflectance spectroscopy with a fiber reflectance probe. Postprocessing techniques are applied to extract an artificial quantitative metric of leak from reflectance spectra at vascular leak sites on the skin of the animal. This leak metric is calculated with respect to elapsed time from irritation in both mustard oil and VEGF treatments on mice and VEGF treatments on rats, showing a repeatable increase in leak metric with leak severity. Furthermore, effects of pressure on the leak metric are observed to have minimal effect on the reflectance spectra, while spatial positioning showed spatially nonuniform leak sites.

McMurdy, John; Reichner, Jonathan; Mathews, Zara; Markey, Mary; Intwala, Sunny; Crawford, Gregory

2009-09-01

147

Quantitative analysis and detection of adulteration in pork using near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Authenticity is an important food quality criterion. Rapid methods for confirming authenticity or detecting adulteration are increasingly demanded by food processors and consumers. Near infrared (NIR) spectroscopy has been used to detect economic adulteration in pork . Pork samples were adulterated with liver and chicken in 10% increments. Prediction and quantitative analysis were done using raw data and pretreatment spectra. The optimal prediction result was achieved by partial least aquares(PLS) regression with standard normal variate(SNV) pretreatment for pork adulterated with liver samples, and the correlation coefficient(R value), the root mean square error of calibration(RMSEC) and the root mean square error of prediction (RMSEP) were 0.97706, 0.0673 and 0.0732, respectively. The best model for pork meat adulterated with chicken samples was obtained by PLS with the raw spectra, and the correlation coefficient(R value), RMSEP and RMSEC were 0.98614, 0.0525, and 0.122, respectively. The result shows that NIR technology can be successfully used to detect adulteration in pork meat adulterated with liver and chicken.

Fan, Yuxia; Cheng, Fang; Xie, Lijuan

2010-04-01

148

ATR-FTIR spectroscopy and quantitative multivariate analysis of paints and coating materials.  

PubMed

The applicability of ATR-FTIR spectroscopy with partial least squares (PLS) data analysis was evaluated for quantifying the components of mixtures of paint binding media and pigments, and alkyd resins. PLS methods were created using a number of standard mixtures. Validation and measurement uncertainty estimation was carried out. Binary, ternary and quaternary mixtures of several common binding media and pigments were quantified, with standard measurement uncertainties in most cases below 3g/100g. Classes of components - aromatic anhydrides and alcohols - used in alkyd resin synthesis were also successfully quantified, with standard uncertainties in the range of 2-3g/100g. This is a more demanding application because in alkyd resins aromatic anhydrides and alcohols have reacted to form a polyester, and are not present in their original forms. Once a PLS method has been calibrated, analysis time and cost are significantly reduced from typical quantitative methods such as GC/MS. This is beneficial in the case of routine analysis where the components are known. PMID:24945861

Hayes, Philippa Alice; Vahur, Signe; Leito, Ivo

2014-12-10

149

Quantitative orientation measurements in thin lipid films by attenuated total reflection infrared spectroscopy.  

PubMed Central

Quantitative orientation measurements by attenuated total reflectance (ATR) infrared spectroscopy require the accurate knowledge of the dichroic ratio and of the mean-square electric fields along the three axes of the ATR crystal. In this paper, polarized ATR spectra of single supported bilayers of the phospholipid dimyristoylphosphatidic acid covered by either air or water have been recorded and the dichroic ratio of the bands due to the methylene stretching vibrations has been calculated. The mean-square electric field amplitudes were calculated using three formalisms, namely the Harrick thin film approximation, the two-phase approximation, and the thickness- and absorption-dependent one. The results show that for dry bilayers, the acyl chain tilt angle varies with the formalism used, while no significant variations are observed for the hydrated bilayers. To test the validity of the different formalisms, s- and p-polarized ATR spectra of a 40-A lipid layer were simulated for different acyl chain tilt angles. The results show that the thickness- and absorption-dependent formalism using the mean values of the electric fields over the film thickness gives the most accurate values of acyl chain tilt angle in dry lipid films. However, for lipid monolayers or bilayers, the tilt angle can be determined with an acceptable accuracy using the Harrick thin film approximation. Finally, this study shows clearly that the uncertainty on the determination of the tilt angle comes mostly from the experimental error on the dichroic ratio and from the knowledge of the refractive index. PMID:9876167

Picard, F; Buffeteau, T; Desbat, B; Auger, M; Pézolet, M

1999-01-01

150

Quantitative identification of metastable magnesium carbonate minerals by solid-state (13)c NMR spectroscopy.  

PubMed

In the conversion of CO2 to mineral carbonates for the permanent geosequestration of CO2, there are multiple magnesium carbonate phases that are potential reaction products. Solid-state (13)C NMR is demonstrated as an effective tool for distinguishing magnesium carbonate phases and quantitatively characterizing magnesium carbonate mixtures. Several of these mineral phases include magnesite, hydromagnesite, dypingite, and nesquehonite, which differ in composition by the number of waters of hydration or the number of crystallographic hydroxyl groups. These carbonates often form in mixtures with nearly overlapping (13)C NMR resonances which makes their identification and analysis difficult. In this study, these phases have been investigated with solid-state (13)C NMR spectroscopy, including both static and magic-angle spinning (MAS) experiments. Static spectra yield chemical shift anisotropy (CSA) lineshapes that are indicative of the site-symmetry variations of the carbon environments. MAS spectra yield isotropic chemical shifts for each crystallographically inequivalent carbon and spin-lattice relaxation times, T1, yield characteristic information that assist in species discrimination. These detailed parameters, and the combination of static and MAS analyses, can aid investigations of mixed carbonates by (13)C NMR. PMID:25437754

Moore, Jeremy K; Surface, J Andrew; Brenner, Allison; Skemer, Philip; Conradi, Mark S; Hayes, Sophia E

2015-01-01

151

Quantitative estimation of carbonation and chloride penetration in reinforced concrete by laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

The penetration profile of chlorine in a reinforced concrete (RC) specimen was determined by laser-induced breakdown spectroscopy (LIBS). The concrete core was prepared from RC beams with cracking damage induced by bending load and salt water spraying. LIBS was performed using a specimen that was obtained by splitting the concrete core, and the line scan of laser pulses gave the two-dimensional emission intensity profiles of 100 × 80 mm2 within one hour. The two-dimensional profile of the emission intensity suggests that the presence of the crack had less effect on the emission intensity when the measurement interval was larger than the crack width. The chlorine emission spectrum was measured without using the buffer gas, which is usually used for chlorine measurement, by collinear double-pulse LIBS. The apparent diffusion coefficient, which is one of the most important parameters for chloride penetration in concrete, was estimated using the depth profile of chlorine emission intensity and Fick's law. The carbonation depth was estimated on the basis of the relationship between carbon and calcium emission intensities. When the carbon emission intensity was statistically higher than the calcium emission intensity at the measurement point, we determined that the point was carbonated. The estimation results were consistent with the spraying test results using phenolphthalein solution. These results suggest that the quantitative estimation by LIBS of carbonation depth and chloride penetration can be performed simultaneously.

Eto, Shuzo; Matsuo, Toyofumi; Matsumura, Takuro; Fujii, Takashi; Tanaka, Masayoshi Y.

2014-11-01

152

First quantitative measurements by IR spectroscopy of dioxins and furans by means of broadly tunable quantum cascade lasers  

NASA Astrophysics Data System (ADS)

We demonstrate the possibility of a quantitative analysis of the concentration of several dioxins and furans, among the most toxic ones, by only using infrared absorption laser spectroscopy. Two broadly tunable quantum cascade lasers, emitting in the mid-infrared, have been used to measure the absorption spectra of dioxins and furans, dissolved in CCl4, in direct absorption mode. The minimum detectable concentrations are inferred by analyzing diluted samples. A comparison between this technique and standard Fourier transform spectroscopy has been carried out and an analysis of future perspectives is reported.

Siciliani de Cumis, M.; D’Amato, F.; Viciani, S.; Patrizi, B.; Foggi, P.; Galea, C. L.

2013-02-01

153

Quantitative Determination of 3-Aminopropylsilane on the Surface of FE3O4 Nanoparticles by Attenuated Total Reflection Infrared Spectroscopy  

NASA Astrophysics Data System (ADS)

A technique for quantitative analysis of 3-aminopropylsilane on the surface of chemically modified Fe3O4 magnetic nanoparticles in the concentration range 0.32-3.03 mmol/g was developed using attenuated total reflection infrared spectroscopy. The technique was based on the ratios of band areas corresponding to Fe-O vibrations of the nanoparticles and Si-O vibrations of the coating as a function of the Si mass fraction in the nanocomposite that was determined by inductively coupled plasma atomic-emission spectroscopy.

Demin, A. M.; Koryakova, O. V.; Krasnov, V. P.

2014-09-01

154

Quantitative water mapping of cryosectioned cells by electron energy-loss spectroscopy.  

PubMed

A direct technique based on electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) has been developed to map subcellular distributions of water in frozen-hydrated biological cryosections. Previously, methods for water determination have been indirect in that they have required the cryosections to be dehydrated first. The new approach makes use of spectrum-imaging, where EELS data are collected in parallel at each pixel. Several operations are required to process the spectra including: subtraction of the detector dark current, deconvolution by the detector point-spread function, removal of plural inelastic scattering and correction for the support film. The resulting single scattering distributions are fitted to standard reference spectra at each pixel, and water content can be determined from the fitting coefficients. Although the darkfield or brightfield image from a hydrated cryosection shows minimal structure, the processed EELS image reveals strong contrast due to variations in water content. Reference spectra have been recorded from the major biomolecules (protein, lipid, carbohydrate, nucleic acid) as well as from vitrified water and crystalline ice. It has been found that quantitative results can be obtained for the majority of subcellular compartments by fitting only water and protein reference spectra, and the accuracy of the method for these compartments has been estimated as +/- 3.5%. With the present instrumentation the maximum allowed dose of 2 x 10(3) e/nm2 limits the useful spatial resolution to around 80 nm for +/- 5% precision at a single pixel. By averaging pixel intensities a value of 56.8% with a precision of +/- 2.0% has been determined for the water content of liver mitochondria. The water mapping technique may prove useful for applications to cell physiology and pathophysiology. PMID:7897645

Sun, S Q; Shi, S L; Hunt, J A; Leapman, R D

1995-01-01

155

Ni speciation in a New Caledonian lateritic regolith: A quantitative X-ray absorption spectroscopy investigation  

NASA Astrophysics Data System (ADS)

Changes in Ni speciation in a 64 m vertical profile of a New Caledonian saprolitic-lateritic regolith developed over ultramafic rocks under tropical weathering conditions were investigated by EXAFS spectroscopy. Quantitative analysis of the EXAFS spectra by linear combination-least squares fitting (LC-LSF) using a large set of model compound spectra showed that Ni hosted in primary silicate minerals (olivine and serpentine) in the bedrock is incorporated in secondary phyllosilicates (serpentine) and Fe-oxides (goethite) in the saprolite unit and mainly in goethite in the laterite unit. A significant concentration of Ni (up to 30% of total Ni) is also hosted by Mn-oxides in the transition laterite (i.e. the lowest part of the laterite unit which contains large amounts of Mn-oxides). However, the amount of Ni associated with Mn-oxides does not exceed 20% of the total Ni in the overlying laterite unit. This sequence of Ni species from bedrock to laterite yields information about the behavior of Ni during tropical weathering of ultramafic rocks. The different Ni distributions in phyllosilicates in the bedrock (randomly distributed) and in the saprolite unit (clustered) indicate two generations of Ni-bearing phyllosilicates. The first, which formed at higher temperature, is related to serpentinization of oceanic crust, whereas the second one, which formed at lower temperature, is associated with post-obduction weathering of ultramafic rocks. In addition, the observed decrease in the proportion of Ni hosted by Mn-oxides from the transition laterite to the upper lateritic horizons indicates dissolution of Mn-oxides during the last stages of differentiation of the lateritic regolith (i.e. lateritization). Finally, the ubiquitous occurrence of Ni-bearing goethite emphasizes the major role of this phase in Ni speciation at the different weathering stages and suggests that goethite represents the major host for Ni in the final tropical weathering stages of New Caledonian ultramafic rocks.

Dublet, Gabrielle; Juillot, Farid; Morin, Guillaume; Fritsch, Emmanuel; Fandeur, Dik; Ona-Nguema, Georges; Brown, Gordon E.

2012-10-01

156

Light Scattering and Absorption Spectroscopy in Three Dimensions Using Quantitative Low Coherence Interferometry for Biomedical Applications  

NASA Astrophysics Data System (ADS)

The behavior of light after interacting with a biological medium reveals a wealth of information that may be used to distinguish between normal and disease states. This may be achieved by simply imaging the morphology of tissues or individual cells, and/or by more sophisticated methods that quantify specific surrogate biomarkers of disease. To this end, the work presented in this dissertation demonstrates novel tools derived from low coherence interferometry (LCI) that quantitatively measure wavelength-dependent scattering and absorption properties of biological samples, with high spectral resolution and micrometer spatial resolution, to provide insight into disease states. The presented work first describes a dual window (DW) method, which decomposes a signal sampled in a single domain (in this case the frequency domain) to a distribution that simultaneously contains information from both the original domain and the conjugate domain (here, the temporal or spatial domain). As the name suggests, the DW method utilizes two independently adjustable windows, each with different spatial and spectral properties to overcome limitations found in other processing methods that seek to obtain the same information. A theoretical treatment is provided, and the method is validated through simulations and experiments. With this tool, the spatially dependent spectral behavior of light after interacting with a biological medium may be analyzed to extract parameters of interest, such as the scattering and absorption properties. The DW method is employed to investigate scattering properties of samples using Fourier domain LCI (fLCI). In this method, induced temporal coherence effects provide insight into structural changes in dominant scatterers, such as cell nuclei within tissue, which can reveal the early stages of cancerous development. fLCI is demonstrated in complex, three-dimensional samples using a scattering phantom and an ex-vivo animal model. The results from the latter study show that fLCI is able to detect changes in the morphology of tissues undergoing precancerous development. The DW method is also employed to enable a novel form of optical coherence tomography (OCT), an imaging modality that uses coherence gating to obtain micrometer-scale, cross-sectional information of tissues. The novel method, named molecular imaging true color spectroscopic OCT (METRiCS OCT), analyses the depth dependent absorption of light to ascertain quantitative information of chromophore concentration, such as hemoglobin. The molecular information is also processed to yield a true color representation of the sample, a unique capability of this approach. A number of experiments, including hemoglobin absorbing phantoms and in-vivo imaging of a chick embryo model and dorsal skinfold window chamber model, demonstrate the power of the method. The final method presented in this dissertation, consists of a spectroscopic approach that interrogates the dispersive biochemical properties of samples to independently probe the scattering and absorption coefficients. To demonstrate this method, named non-linear phase dispersion spectroscopy (NLDS), a careful analysis of LCI signals is presented. The method is verified using measurements from samples that scatter and absorb light. Lastly, NLDS is combined with phase microscopy to achieve molecular imaging with sub-micron spatial resolution. Imaging of red blood cells (RBCs) shows that the method enables highly sensitive measurements that can quantify hemoglobin content from single RBCs.

Robles, Francisco E.

157

Experimental demonstration of quantitation errors in MR spectroscopy resulting from saturation corrections under changing conditions.  

PubMed

Metabolite concentration measurements in in vivo NMR are generally performed under partially saturated conditions, with correction for partial saturation performed after data collection using a measured saturation factor. Here, we present an experimental test of the hypothesis that quantitation errors can occur due to application of such saturation factor corrections in changing systems. Thus, this extends our previous theoretical work on quantitation errors due to varying saturation factors. We obtained results for two systems frequently studied by 31P NMR, the ischemic rat heart and the electrically stimulated rat gastrocnemius muscle. The results are interpreted in light of previous theoretical work which defined the degree of saturation occurring in a one-pulse experiment for a system with given spin-lattice relaxation times, T(1)s, equilibrium magnetizations, M(0)s, and reaction rates. We found that (i) the assumption of constancy of saturation factors leads to quantitation errors on the order of 40% in inorganic phosphate; (ii) the dominant contributor to the quantitation errors in inorganic phosphate is most likely changes in T(1); (iii) T(1) and M(0) changes between control and intervention periods, and chemical exchange contribute to different extents to quantitation errors in phosphocreatine and gamma-ATP; (iv) relatively small increases in interpulse delay substantially decreased quantitation errors for metabolites in ischemic rat hearts; (v) random error due to finite SNR led to approximately 4% error in quantitation, and hence was a substantially smaller contributor than were changes in saturation factors. PMID:12713964

Galbán, Craig J; Ellis, Scott J; Spencer, Richard G S

2003-04-01

158

Experimental demonstration of quantitation errors in MR spectroscopy resulting from saturation corrections under changing conditions  

NASA Astrophysics Data System (ADS)

Metabolite concentration measurements in in vivo NMR are generally performed under partially saturated conditions, with correction for partial saturation performed after data collection using a measured saturation factor. Here, we present an experimental test of the hypothesis that quantitation errors can occur due to application of such saturation factor corrections in changing systems. Thus, this extends our previous theoretical work on quantitation errors due to varying saturation factors. We obtained results for two systems frequently studied by 31P NMR, the ischemic rat heart and the electrically stimulated rat gastrocnemius muscle. The results are interpreted in light of previous theoretical work which defined the degree of saturation occurring in a one-pulse experiment for a system with given spin-lattice relaxation times, T1s, equilibrium magnetizations, M0s, and reaction rates. We found that (i) the assumption of constancy of saturation factors leads to quantitation errors on the order of 40% in inorganic phosphate; (ii) the dominant contributor to the quantitation errors in inorganic phosphate is most likely changes in T1; (iii) T1 and M0 changes between control and intervention periods, and chemical exchange contribute to different extents to quantitation errors in phosphocreatine and ?-ATP; (iv) relatively small increases in interpulse delay substantially decreased quantitation errors for metabolites in ischemic rat hearts; (v) random error due to finite SNR led to approximately 4% error in quantitation, and hence was a substantially smaller contributor than were changes in saturation factors.

Galbán, Craig J.; Ellis, Scott J.; Spencer, Richard G. S.

2003-04-01

159

Quantitative assessment of the ion-beam irradiation induced direct damage of nucleic acid bases through FTIR spectroscopy  

NASA Astrophysics Data System (ADS)

Energetic particles exist ubiquitously in nature, and when they hit DNA molecules in organisms, they may induce critical biological effects such as mutation. It is however still a challenge to measure directly and quantitatively the damage imposed by the energetic ions on target DNA molecules. In this work we attempted to employ Fourier transformation infrared (FTIR) spectroscopy to assess the ion-induced direct damage of four nucleic acid bases, namely, thymine (T), cytosine (C), guanine (G), and adenine (A), which are the building blocks of DNA molecules. The samples were prepared as thin films, irradiated by argon ion-beams at raised ion fluences, and in the meantime measured by FTIR spectroscopy for the damage in a quasi-in-situ manner. It was found that the low-energy ion-beam induced radiosensitivity of the four bases shows the sequence G > T > C > A, wherein the possible mechanism was also discussed.

Huang, Qing; Su, Xi; Yao, Guohua; Lu, Yilin; Ke, Zhigang; Liu, Jinghua; Wu, Yuejin; Yu, Zengliang

2014-07-01

160

Quantitative Raman Spectroscopy to monitor microbial metabolism in situ under pressure  

NASA Astrophysics Data System (ADS)

Although high hydrostatic pressure (HHP) biotopes are ubiquitous on Earth, little is known about the metabolism of piezophile organisms. Cell culture under HHP can be technically challenging, and equipment- dependent. In addition, the depressurization step required for analysis can lead to erroneous data. Therefore, to understand how piezophile organisms react to pressure, it is crucial to be able to monitor their activity in situ under HHP. We developed the use of Quantitative Raman Spectroscopy (QRS, 1) to monitor in situ the metabolism of organic molecules. This technique is based on the specific spectral signature of an analyte from which its concentration can be deduced. An application of this technique to the monitoring of alcoholic fermentation by the piezotolerant micro-eucaryote Saccharomyces cerevisiae is presented. Ethanol fermentation from glucose was monitored during 24h from ambient P up to 100 MPa in the low- pressure Diamond Anvil Cell (lpDAC, 2). The experimental compression chamber consisted in a 300 ?m-thick Ni gasket in which a 500 ?m-diameter hole was drilled. Early-stationnary yeast cells were inoculated into fresh low-fluorescence medium containing 0.15 M of glucose. Ethanol concentration was determined in situ by QRS using the symmetric C-C stretching mode of ethanol at 878 cm-1 normalizing the data to the intensity of the sulfate S-O stretching mode at 980 cm-1. In our setup, the detection limit of ethanol is lower than 0.05 mM with a precision below 1%. At ambient P, ethanol production in the lpDAC and in control experiments proceeds with the same kinetics. Thus, yeast is not affected by its confinement. This is further confirmed by its ability to bud with a generation time similar to control experiments performed in glass tubes at ambient pressure inside the lpDAC. Ethanol production by yeast occurs to at least 65 MPa (3). At 10 MPa, fermentation proceeds 3 times faster than at ambient P. Fermentation rates decrease linearly from 20 to at least 65 MPa. No ethanol was detected at 100 MPa. From these data, the pressure at which ethanol fermentation stops in yeast was calculated to be 87±7 MPa. These results indicate that the activity of one or several enzymes of the glycolytic pathway is enhanced at low pressure. At higher pressure, they become progressively repressed, and are completely inhibited above 87 MPa. Our in situ monitoring constitutes a direct demonstration of yeast metabolism in situ under pressure up to 100 MPa. Our data agree with previous ex-situ data by Abe and Horikoshi (4). However, we observed that ethanol production is not completely inhibited around 50 MPa as predicted, but could be detected at significantly higher pressures (up to 87 MPa). QSR is a powerful method to monitor microbial activities, since almost any organic molecule with a carbon chain ranging from 1 to 6 carbon can be detected and quantified. The only limitation of QSR is that the Raman spectrum of the molecule exhibits at least one peak not masked by the spectrum of the growth medium. 1 Pelletier M J Appl Spectr 57:20A-42A, 2003 2 Daniel I, Oger P, Picard A, Cardon H and Chervin J-C (submitted to Rev Sci Instr) 3 Picard A, Daniel I, Montagnac G and Oger P (submitted to Extremophiles) 4 Abe F and Horikoshi K Extremophiles 1: 89-93, 1997

Picard, A.; Daniel, I.; Oger, P.

2006-12-01

161

Direct and quantitative broadband absorptance micro/nano spectroscopy using FTIR and bilayer cantilever probes  

E-print Network

Optical properties of micro/nano materials are important for many applications in biology, optoelectronics, and energy. In this thesis, a method is described to directly measure the quantitative absorptance spectra of ...

Hsu, Wei-Chun

2012-01-01

162

Real time quantitative Raman spectroscopy of supported metal oxide catalysts without the need of an internal standard.  

PubMed

In continuation to the possibility of using a combined operando Raman/UV-Vis-NIR set-up for conducting qualitative Raman spectroscopy, the possibilities for quantitative Raman spectroscopic measurements of supported metal oxide catalysts under working conditions without the need of an internal standard have been explored. The dehydrogenation of propane over an industrial-like 13 wt% Cr/Al203 catalyst was used as a model system. During reaction, the catalytic solid was continuously monitored by both UV-Vis-NIR and Raman spectroscopy. As the dehydrogenation proceeds, the catalyst gradually darkens due to coke formation and consequently the UV-Vis-NIR diffuse reflectance and Raman scattered signal progressively decrease in intensity. The formation of coke was confirmed with TEOM, TGA and Raman. The measured Raman spectra can be used as a quantitative measure of the amount of carbonaceous deposits at the catalyst surface provided that a correction factor G(R(infinity)) is applied. This factor can be directly calculated from the corresponding UV-Vis-NIR diffuse reflectance spectra. The validity of the approach is compared with one, in which an internal boron nitride standard is added to the catalytic solid. It will be shown that the proposed methodology allows measurement of the amount of carbonaceous deposits on a catalyst material inside a reactor as a function of reaction time and catalyst bed height. As a consequence, an elegant technique for on-line process control of e.g. an industrial propane dehydrogenation reactor emerges. PMID:19785192

Tinnemans, S J; Kox, M H F; Nijhuis, T A; Visser, T; Weckhuysen, B M

2005-01-01

163

Expanding the limits of human blood metabolite quantitation using NMR spectroscopy.  

PubMed

A current challenge in metabolomics is the reliable quantitation of many metabolites. Limited resolution and sensitivity combined with the challenges associated with unknown metabolite identification have restricted both the number and the quantitative accuracy of blood metabolites. Focused on alleviating this bottleneck in NMR-based metabolomics, investigations of pooled human serum combining an array of 1D/2D NMR experiments at 800 MHz, database searches, and spiking with authentic compounds enabled the identification of 67 blood metabolites. Many of these (?1/3) are new compared with those reported previously as a part of the Human Serum Metabolome Database. In addition, considering both the high reproducibility and quantitative nature of NMR as well as the sensitivity of NMR chemical shifts to altered sample conditions, experimental protocols and comprehensive peak annotations are provided here as a guide for identification and quantitation of the new pool of blood metabolites for routine applications. Further, investigations focused on the evaluation of quantitation using organic solvents revealed a surprisingly poor performance for protein precipitation using acetonitrile. One-third of the detected metabolites were attenuated by 10-67% compared with methanol precipitation at the same solvent-to-serum ratio of 2:1 (v/v). Nearly 2/3 of the metabolites were further attenuated by up to 65% upon increasing the acetonitrile-to-serum ratio to 4:1 (v/v). These results, combined with the newly established identity for many unknown metabolites in the NMR spectrum, offer new avenues for human serum/plasma-based metabolomics. Further, the ability to quantitatively evaluate nearly 70 blood metabolites that represent numerous classes, including amino acids, organic acids, carbohydrates, and heterocyclic compounds, using a simple and highly reproducible analytical method such as NMR may potentially guide the evaluation of samples for analysis using mass spectrometry. PMID:25485990

Nagana Gowda, G A; Gowda, Yashas N; Raftery, Daniel

2015-01-01

164

Spectroscopic (FT-IR, FT-Raman and UV-Visible) investigations, NMR chemical shielding anisotropy (CSA) parameters of 2,6-Diamino-4-chloropyrimidine for dye sensitized solar cells using density functional theory.  

PubMed

The molecular structure, geometry optimization, vibrational frequencies of organic dye sensitizer 2,6-Diamino-4-chloropyrimidine (DACP) were studied based on Hartree-Fock (HF) and density functional theory (DFT) using B3LYP methods with 6-311++G(d,p) basis set. Ultraviolet-Visible (UV-Vis) spectrum was investigated by time dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the UV-Visible regions were assigned based on TD-DFT calculation. The absorption bands are assigned to transitions. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer DACP is due to an electron injection process from excited dye to the semiconductor's conduction band. The observed and the calculated frequencies are found to be in good agreement. The energies of the frontier molecular orbitals (FMOS) have also been determined. The chemical shielding anisotropic (CSA) parameters are calculated from the NMR analysis, Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. PMID:25459717

Gladis Anitha, E; Joseph Vedhagiri, S; Parimala, K

2014-10-24

165

Spectroscopic (FT-IR, FT-Raman and UV-Visible) investigations, NMR chemical shielding anisotropy (CSA) parameters of 2,6-Diamino-4-chloropyrimidine for dye sensitized solar cells using density functional theory  

NASA Astrophysics Data System (ADS)

The molecular structure, geometry optimization, vibrational frequencies of organic dye sensitizer 2,6-Diamino-4-chloropyrimidine (DACP) were studied based on Hartree-Fock (HF) and density functional theory (DFT) using B3LYP methods with 6-311++G(d,p) basis set. Ultraviolet-Visible (UV-Vis) spectrum was investigated by time dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the UV-Visible regions were assigned based on TD-DFT calculation. The absorption bands are assigned to transitions. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer DACP is due to an electron injection process from excited dye to the semiconductor's conduction band. The observed and the calculated frequencies are found to be in good agreement. The energies of the frontier molecular orbitals (FMOS) have also been determined. The chemical shielding anisotropic (CSA) parameters are calculated from the NMR analysis, Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

Gladis Anitha, E.; Joseph Vedhagiri, S.; Parimala, K.

2015-02-01

166

Longitudinal quantitative proton magnetic resonance spectroscopy of the hippocampus in Alzheimer's disease  

Microsoft Academic Search

Summary Changes in metabolites detected by proton magnetic resonance spectroscopy (1H MRS) of the brain have been demonstrated in Alzheimer's disease. Our object- ives were, first, longitudinally to measure absolute con- centrations of metabolites in both hippocampi, the sites of early Alzheimer's disease, in patients with clinical Alzheimer's disease and controls; secondly, to separate the relative contribution of atrophy and

Ruth M. Dixon; Kevin M. Bradley; Marc M. Budge; Peter Styles; A. David Smith

2002-01-01

167

Quantitative determination of saturated and unsaturated fatty acids in edible oils by infrared spectroscopy and chemometrics  

Microsoft Academic Search

The fatty acids of eight edible oil samples with varying composition were saponified, esterified into methyl esters and analysed by gas chromatography. These composition values were used in calculating the composition of 25 syntheic edible oil mixtures containing a wide range of saturation and unsaturation. All these 33 oils were then analysed by infrared spectroscopy using single reflectance technique. The

Alfred A. Christy; Per K. Egeberg

2006-01-01

168

Quantitative arsenic speciation in mine tailings using X-ray absorption spectroscopy  

Microsoft Academic Search

X-ray absorption fine structure spectroscopy (XAFS) was used to determine arsenic (As) oxidation state, local coordination (to a radius of 7Aaround As), and the relative proportion of different As species in model compounds and three California mine wastes: fully oxidized tailings (Ruth Mine), partially oxidized tailings (Argonaut Mine), and roast- ed sulfide ore (Spenceville Mine). Mineralogy was characterized by Rietveld

ANDREA L. FOSTER; GORDON E. BROWN JR; TRACY N. TINGLE; GEORGE A. PARKS

169

[Qualitative and quantitative research on sulfur fumigation of Angelicae Dahuricae Radix (Baizhi) by near-infrared spectroscopy].  

PubMed

The contents of coumarins in the sulfur fumigated Angelicae Dahuricae Radix (Baizhi, ADR) were reduced significantly. To achieve the quality control of ADR, the qualitative identification of sulfur fumigated ADR and quantitative model of imperatorin content should be established. The near-infrared (NIR) spectrograms of non-sulfur and sulfur fumigated ADR were collected by NIR diffuse reflectance spectroscopy technology and pretreated by the method of first derivative derivation and vector normalization. The Ward's Algorithm method was used for the cluster analysis. The non-sulfur and sulfur fumigated ADR can be quickly identified in the range of 8,806. 0-3 811.0 cm(-1) based on the cluster analysis. The NIR quantitative model of imperatorin was established by the contents of imperatorin determined by HPLC in combination with partial least squares regression analysis. According to the calibration model established in this study, correlation coefficients (R2), the root-mean-square error of cross-validation (RMSECV), and the root-mean-square error of prediction (RMSEP) for imperatorin were 0.982 8, 0.006 8, 0.011 8, respectively. The quantitative model of imperatorin can be applied to determine the content of imperatorin in ADR accurately. PMID:25282896

Wu, Xiao-Yi; Chao, Zhi-Mao; Sun, Wen; Wang, Chun

2014-05-01

170

Quantitative detection of uric Acid by electrochemical-surface enhanced Raman spectroscopy using a multilayered au/ag substrate.  

PubMed

Uric acid is a potential important biomarker in urine and serum samples for early diagnosis of preeclampsia, a life-threatening hypertensive disorder that occurs during pregnancy. Preeclampsia is a leading cause of maternal death, especially in developing nation settings. Quantitative detection of uric acid for rapid and routine diagnosis of early preeclampsia using electrochemical-surface enhanced Raman spectroscopy (EC-SERS) is presented herein. A uniform EC-SERS active Au/Ag substrate was developed by depositing nearly monodisperse gold and silver nanoparticles on the carbon working electrode surface of screen printed electrodes. The multilayered Au/Ag substrates were characterized by electron microscopy and used for quantitative detection of uric acid in 0.1 M NaF and synthetic urine at clinically relevant concentrations. These results showed a linear relationship between the EC-SERS signal intensity and the uric acid concentration. Relative errors calculated for selected concentrations were all within the Clinical Laboratory Improvement Amendments (CLIA) criterion for uric acid analysis (±17%). It is believed that routine and early diagnosis of disease could be possible through such quantitative detection of biomarkers in patient samples using this EC-SERS method. PMID:25483146

Zhao, Lili; Blackburn, Jonathan; Brosseau, Christa L

2015-01-01

171

Absolute Quantitation of Bacterial Biofilm Adhesion and Viscoelasticity by Microbead Force Spectroscopy  

E-print Network

Absolute Quantitation of Bacterial Biofilm Adhesion and Viscoelasticity by Microbead Force of Guelph, Guelph, ON N1G 2W1, Canada ABSTRACT Bacterial biofilms are the most prevalent mode of bacterial growth in nature. Adhesive and viscoelastic properties of bacteria play important roles at different

Dutcher, John

172

Quantitative modeling of electron spectroscopy intensities for supported nanoparticles: The hemispherical cap model for non-normal detection  

NASA Astrophysics Data System (ADS)

Nanoparticles of one element or compound dispersed across the surface of another substrate element or compound form the basis for many materials of great technological importance, such as heterogeneous catalysts, fuel cells and other electrocatalysts, photocatalysts, chemical sensors and biomaterials. They also form during film growth by deposition in many fabrication processes. The average size and number density of such nanoparticles are often very important, and these can be estimated with electron microscopy or scanning tunneling microscopy. However, this is very time consuming and often unavailable with sufficient resolution when the particle size is ~ 1 nm. Because the probe depth of electron spectroscopies like X-Ray Photoelectron Spectroscopy (XPS) or Auger Electron Spectroscopy (AES) is ~ 1 nm, these provide quantitative information on both the total amount of adsorbed material when it is in the form of such small nanoparticles, and the particle thickness. For electron spectroscopy conducted with electron detection normal to the surface, Diebold et al. (1993) derived analytical relationships between the signal intensities for the adsorbate and substrate and the particles' average size and number density, under the assumption that all the particles have hemispherical shape and the same radius. In this paper, we report a simple angle- and particle-size-dependent correction factor that can be applied to these analytical expressions so that they can also be extended to measurements made at other detection angles away from the surface normal. This correction factor is computed using numerical integration and presented for use in future modeling. This correction factor is large (> 2) for angles beyond 60°, so comparing model predictions to measurements at both 0° and ? 60° will also provide a new means for testing the model's assumptions (hemispherical shape and fixed size particles). The ability to compare the hemispherical cap model at several angles simultaneously also should enable more accurate estimates of surface structural parameters when elastic diffraction effects cause strong peaks in the angular distributions of emitted electrons.

Sharp, James C.; Campbell, Charles T.

2015-02-01

173

Terahertz time-domain spectroscopy and the quantitative monitoring of mechanochemical cocrystal formation  

NASA Astrophysics Data System (ADS)

Terahertz (THz) radiation probes intermolecular interactions through crystal lattice vibrations, allowing the characterization of solid materials. Thus, THz spectroscopy is a promising alternative to mainstream solid-state analytical tools such as X-ray diffraction or thermal analysis. The method provides the benefits of online measurement, remote sampling and three-dimensional imaging, all of which are attractive for quality control and security applications. In the context of pharmaceutical solids, THz spectroscopy can differentiate and quantify different forms of active pharmaceutical ingredients. Here, we apply this technique to monitor a dynamic process involving two molecular crystals. In particular, we follow the mechanochemical construction of a two-component cocrystal by grinding together phenazine (phen) and mesaconic acid (mes). To rationalize the observed changes in the spectra, we conduct lattice dynamics calculations that lead to the tentative assignment of at least one feature in the cocrystal THz spectrum.

Lien Nguyen, K.; Friš?i?, Tomislav; Day, Graeme M.; Gladden, Lynn F.; Jones, William

2007-03-01

174

Quantitative characterisation of H-Mordenite zeolite structure by infrared spectroscopy using benzene adsorption  

Microsoft Academic Search

Infrared spectroscopy has been used to characterise the Brönsted acidity, the hydroxyls of H-Mordenite (HM) zeolite and the interaction of hydroxyls with benzene molecules. After pre-treatment under dry oxygen and then under vacuum at 723 K, three hydroxyl groups at 3749, 3660 and 3608 cm?1, assigned to terminal silanol, extraframework Al–OH and framework bridged Si–OH–Al species, respectively, have been detected.

Bao-Lian Su; Valérie Norberg

2001-01-01

175

[Quantitative determination of parameters of substrate using near-infrared spectroscopy technique].  

PubMed

Soilless culture has many virtues, such as space saving, time saving, etc.. It has become one of the technologies which developed fastest in agricultural products. The selection of substrate is one of the keys to determining the success of soilless culture. Therefore, it is important to rapidly determine the parameters of substrate. In the present paper, moisture, electronic conductivity and pH values of substrate were tested by near-infrared (NIR) spectroscopy. The spectra were preprocessed by baseline correction and derivative. Partial least squares (PLS) regression model was built using different wave bands. It was found that baseline drift was improved after correction. NIR spectroscopy can be used to determine EC value of substrate. The correlation coefficient r, root-mean-square error of the cross validation (RMSECV), relative percent difference (RPD) and bias of the optimum PLS was 0.923 6, 634 micros x cm(-1), 3.11 and 19.8 micros x cm(-1), respectively, when the best wave band was 4 246.7 - 7 502.2 cm(-1) and the best factor was 7. NIR spectroscopy technique can also be used to predict moisture of substrate although the accuracy of model should be improved. However, it can not be used to predict pH value of substrate. PMID:22242487

Yu, Yong-Hua

2011-11-01

176

Quantitative determination of dimethylaminoethanol in cosmetic formulations by nuclear magnetic resonance spectroscopy.  

PubMed

A nuclear magnetic resonance (NMR) spectroscopic method was validated for the quantitative determination of dimethylaminoethanol (DMAE) in cosmetic formulations. The linearity in the range from 0.5000 to 1.5000 g (DMAE salt/mass maleic acid) presents a correlation coefficient > 0.99 for all DMAE salts. The repeatability (intraday), expressed as relative standard deviation, ranged from 1.08 to 1.44% for samples and 1.31 to 1.88% for raw materials. The detection limit and quantitation limit were 0.0017 and 0.0051 g for DMAE, 0.0018 and 0.0054 g for DMAE bitartrate, and 0.0023 and 0.0071 g for DMAE acetamidobenzoate, respectively. The proposed method is simple, precise, and accurate and can be used in the quality control of raw materials and cosmetic gels containing these compounds as active substances. PMID:19202790

Batista, Ivani Aparecida Soares de Andrade; Gonçalves, Maria Inês de Almeida; Singh, Anil Kumar; Hackmann, Erika Rosa Maria Kedor; Santoro, Maria Inês Rocha Miritello

2008-01-01

177

Quantitative determination of captopril and prednisolone in tablets by FT-Raman spectroscopy  

Microsoft Academic Search

A procedure for the quantitative determination of captopril and prednisolone in commercial tablets based on partial least squares (PLS) and principal component regression (PCR) treatment of FT-Raman spectroscopic data is described. In the studied medicines active pharmaceutical ingredients (APIs) constitute 4.2–16.7% of the tablet mass. Results obtained from calibration models built using unnormalised spectra were compared with the values found

Sylwester Mazurek; Roman Szostak

2006-01-01

178

Rapid separation and quantitation of curcuminoids combining pseudo two dimensional liquid flash chromatography and NMR spectroscopy  

PubMed Central

Rapid separation, characterization and quantitation of curcuminoids are important owing to their numerous pharmacological properties including antimicrobial, antiviral, antifungal, anticancer, and anti-inflammatory activities. In the present study, pseudo two dimensional liquid flash chromatography was used for the separation of four curcuminoids (curcumin, demethoxy curcumin, bisdemethoxy curcumin and dihydro bisdemethoxy curcumin) for the first time. Silica and diol columns were used for separation of curcuminoids using gradient mobile phase. The separated peaks were monitored at 244, 360 nm to obtain four compounds. The purity of compounds were determined by rapid quantitative 1H NMR (qNMR) using 3-(trimethylsilyl) propionic-(2,2,3,3-d4) acid sodium salt (TSP-d4) (0.012%) in D2O. These results were compared with those obtained by HPLC method. The purity of isolated curcuminoids using pseudo 2D chromatography was found to be in the range of 92.4–95.45%. The structures of these compounds were characterized unambiguously using 13C (APT) NMR spectra. The developed pseudo 2D separation technique has the advantage of simplified automation with shorter run time compared to conventional separation techniques. The method that combines rapid pseudo 2D separation and simple quantitation using qNMR reported herein can be of wide utility for routine analysis of curcuminoids in complex mixtures. PMID:24013126

Jayaprakasha, G. K.; Gowda, G.A. Nagana; Marquez, Sixto; Patil, Bhimanagouda S.

2013-01-01

179

Thin-film quantitative microanalysis of the cation composition in ceramics with ultrathin-window-type energy-dispersive X-ray spectroscopy in a transmission electron microscope  

Microsoft Academic Search

Quantative elemental microanalysis of the cation composition in ceramics was examined by ultrathin-window-type energy-dispersive X-ray spectroscopy (EDS) in a transmission electron microscope. One object of this investigation was the development of a quantitative analysis method by which absorption correction can be carried out. Another was to determine how anions in ceramics are treated in quantitative elemental analysis. The two-beam intensity

Junya Kondoh; Shiomi Kikuchi; Yoichi Timii; Yasuhiko Ito

1997-01-01

180

Quantitative performance measurements of bent crystal Laue analyzers for X-ray fluorescence spectroscopy  

PubMed Central

Third-generation synchrotron radiation sources pose difficult challenges for energy-dispersive detectors for XAFS because of their count rate limitations. One solution to this problem is the bent crystal Laue analyzer (BCLA), which removes most of the undesired scatter and fluorescence before it reaches the detector, effectively eliminating detector saturation due to background. In this paper experimental measurements of BCLA performance in conjunction with a 13-element germanium detector, and a quantitative analysis of the signal-to-noise improvement of BCLAs are presented. The performance of BCLAs are compared with filters and slits. PMID:22514172

Karanfil, C.; Bunker, G.; Newville, M.; Segre, C. U.; Chapman, D.

2012-01-01

181

Qualitative and Quantitative Control of Carbonated Cola Beverages Using 1H NMR Spectroscopy  

PubMed Central

1H Nuclear magnetic resonance (NMR) spectroscopy (400 MHz) was used in the context of food surveillance to develop a reliable analytical tool to differentiate brands of cola beverages and to quantify selected constituents of the soft drinks. The preparation of the samples required only degassing and addition of 0.1% of TSP in D2O for locking and referencing followed by adjustment of pH to 4.5. The NMR spectra obtained can be considered as “fingerprints” and were analyzed by principal component analysis (PCA). Clusters from colas of the same brand were observed, and significant differences between premium and discount brands were found. The quantification of caffeine, acesulfame-K, aspartame, cyclamate, benzoate, hydroxymethylfurfural (HMF), sulfite ammonia caramel (E 150D), and vanillin was simultaneously possible using external calibration curves and applying TSP as internal standard. Limits of detection for caffeine, aspartame, acesulfame-K, and benzoate were 1.7, 3.5, 0.8, and 1.0 mg/L, respectively. Hence, NMR spectroscopy combined with chemometrics is an efficient tool for simultaneous identification of soft drinks and quantification of selected constituents. PMID:22356160

2012-01-01

182

Qualitative and quantitative study of polymorphic forms in drug formulations by near infrared FT-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Near infrared FT-Raman spectroscopy was applied for the determination of polymorphic forms in a number of commercial drug products containing the polymorphic drug compounds sorbitol, mannitol, famotidine, acemetacin, carbamazepine, meprobamate and phenylbutazone. The crystal forms present in the drug products were identified based on the position, intensity and shape of characteristic bands. Quantitative analysis of a mixture of two crystal forms of mannitol in a drug product was carried out using a partial least-squares method. In drug products containing meprobamate, sorbitol, and carbamazepine, the thermodynamically stable form was found exclusively, whereas metastable polymorphs were found in solid dosage forms of acemetacin, phenylbutazone, famotidine and mannitol. A mixture of two polymorphic forms of mannitol in Lipobay tablets was determined to consist of 30.8±3.8% of the metastable modification I. The simple sample preparation, the occurrence of sharp bands in the spectra as well as the high reproducibility and accuracy qualifies FT-Raman spectroscopy for the identification and quantification of crystal forms in drug products. The method is perfectly suited to meet the regulatory requirements of monitoring crystal forms during processing and storage and often succeeds in detecting the present crystal form in drug products even when the used excipients are not known.

Auer, Martin E.; Griesser, Ulrich J.; Sawatzki, Juergen

2003-12-01

183

Partial Least Squares and Neural Networks for Quantitative Calibration of Laser-induced Breakdown Spectroscopy (LIBs) of Geologic Samples  

NASA Technical Reports Server (NTRS)

The ChemCam instrument [1] on the Mars Science Laboratory (MSL) rover will be used to obtain the chemical composition of surface targets within 7 m of the rover using Laser Induced Breakdown Spectroscopy (LIBS). ChemCam analyzes atomic emission spectra (240-800 nm) from a plasma created by a pulsed Nd:KGW 1067 nm laser. The LIBS spectra can be used in a semiquantitative way to rapidly classify targets (e.g., basalt, andesite, carbonate, sulfate, etc.) and in a quantitative way to estimate their major and minor element chemical compositions. Quantitative chemical analysis from LIBS spectra is complicated by a number of factors, including chemical matrix effects [2]. Recent work has shown promising results using multivariate techniques such as partial least squares (PLS) regression and artificial neural networks (ANN) to predict elemental abundances in samples [e.g. 2-6]. To develop, refine, and evaluate analysis schemes for LIBS spectra of geologic materials, we collected spectra of a diverse set of well-characterized natural geologic samples and are comparing the predictive abilities of PLS, cascade correlation ANN (CC-ANN) and multilayer perceptron ANN (MLP-ANN) analysis procedures.

Anderson, R. B.; Morris, Richard V.; Clegg, S. M.; Humphries, S. D.; Wiens, R. C.; Bell, J. F., III; Mertzman, S. A.

2010-01-01

184

Biosynthesis of drug metabolites and quantitation using NMR spectroscopy for use in pharmacologic and drug metabolism studies.  

PubMed

The contribution of drug metabolites to the pharmacologic and toxicologic activity of a drug can be important; however, for a variety of reasons metabolites can frequently be difficult to synthesize. To meet the need of having samples of drug metabolites for further study, we have developed biosynthetic methods coupled with quantitative NMR spectroscopy (qNMR) to generate solutions of metabolites of known structure and concentration. These quantitative samples can be used in a variety of ways when a synthetic sample is unavailable, including pharmacologic assays, standards for in vitro work to help establish clearance pathways, and/or as analytical standards for bioanalytical work to ascertain exposure, among others. We illustrate five examples of metabolite biosynthesis and qNMR. The types of metabolites include one glucuronide and four oxidative products. Concentrations of the isolated metabolite stock solutions ranged from 0.048 to 8.3 mM, with volumes from approximately 0.04 to 0.150 ml in hexadeutarated dimethylsulfoxide. These specific quantified isolates were used as standards in the drug discovery setting as substrates in pharmacology assays, for bioanalytical assays to establish exposure, and in variety of routine absorption, distribution, metabolism, and excretion assays, such as protein binding and determining blood-to-plasma ratios. The methods used to generate these materials are described in detail with the objective that these methods can be generally used for metabolite biosynthesis and isolation. PMID:25053618

Walker, Gregory S; Bauman, Jonathan N; Ryder, Tim F; Smith, Evan B; Spracklin, Douglas K; Obach, R Scott

2014-10-01

185

Quantitative monitoring of radiation induced skin toxicities in nude mice using optical biomarkers measured from diffuse optical reflectance spectroscopy  

PubMed Central

Monitoring the onset of erythema following external beam radiation therapy has the potential to offer a means of managing skin toxicities via biological targeted agents – prior to full progression. However, current skin toxicity scoring systems are subjective and provide at best a qualitative evaluation. Here, we investigate the potential of diffuse optical spectroscopy (DOS) to provide quantitative metrics for scoring skin toxicity. A DOS fiberoptic reflectance probe was used to collect white light spectra at two probing depths using two short fixed source-collector pairs with optical probing depths sensitive to the skin surface. The acquired spectra were fit to a diffusion theory model of light transport in tissue to extract optical biomarkers (hemoglobin concentration, oxygen saturation, scattering power and slope) from superficial skin layers of nude mice, which were subjected to erythema inducing doses of ionizing radiation. A statistically significant increase in oxygenated hemoglobin (p < 0.0016) was found in the skin post-irradiation – confirming previous reports. More interesting, we observed for the first time that the spectral scattering parameters, A (p = 0.026) and k (p = 0.011), were an indicator of erythema at day 6 and could potentially serve as an early detection optical biomarker of skin toxicity. Our data suggests that reflectance DOS may be employed to provide quantitative assessment of skin toxicities following curative doses of external beam radiation. PMID:24876997

Yohan, Darren; Kim, Anthony; Korpela, Elina; Liu, Stanley; Niu, Carolyn; Wilson, Brian C; Chin, Lee CL

2014-01-01

186

Quantitative X-ray Absorption and Emission Spectroscopies: Electronic Structure Elucidation of Cu2S and CuS  

PubMed Central

The electronic structures of Cu2S and CuS have been under intense scrutiny, with the aim of understanding the relationship between their electronic structures and commercially important physical properties. Here, X-ray absorption and emission spectroscopic data have been analyzed using a quantitative, molecular orbital (MO) based approach to understand the electronic structure of these two complex systems. Cu2S is shown to have a significant amount of Cu2+ sites and therefore Cu0 centers. The presence of low-valent Cu is correlated with the electrical conductivity of Cu2S, especially at high temperatures. CuS is shown to have tetrahedral Cu2+ and trigonal Cu1+ sites, with crystal planes that have alternating high and low charge on the Cu centers. These alternating charges may contribute to internal energy transitions required for photoluminescence properties. The in-depth electronic structure solutions presented here not only solve a complicated much-debated problem, but also demonstrate the strength of quantitative MO based approach to X-ray spectroscopies PMID:23781327

Kumar, Prashant; Nagarajan, Rajamani

2013-01-01

187

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

PubMed

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

Saravanan, S; Balachandran, V

2014-09-15

188

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

NASA Astrophysics Data System (ADS)

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

Saravanan, S.; Balachandran, V.

2014-09-01

189

Experimental spectroscopic (FTIR, FT-Raman, FT-NMR, UV-Visible) and DFT studies of 1-ethyl-1,4-dihydro-7-methyl-4oxo-1,8 napthyridine-3-carboxylic acids.  

PubMed

The solid phase FTIR and FT-Raman spectra of 1-ethyl-1,4-dihydro-7-methyl-4oxo-1,8 napthyridine-3-carboxylic acid (EDMONCA) have been recorded in the regions 4000-500 and 4000-400 cm(-1) respectively. The equilibrium geometry, harmonic vibrational frequencies have been investigated by DFT/B3LYP and B3PW91 methods with 6-311G (d,p) basis set. The different between the observed and scaled wave number values of most of the fundamental is very small. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFFM). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV-Visible spectrum of the compound was recorded and the electronic properties HOMO and LOMO energies were measured. The electric dipole moment (?D) and first hyperpolarizability (?tot) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the EDMONCA molecule may have microscopic nonlinear optics (NLO) behavior with non-zero values. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shift of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Thermal stability of EDMONCA was studied by thermogravimetric analysis (TGA). Next Fukui function was calculated to explain the chemical selectivity or reactivity site in EDMONCA. Finally molecular electrostatic potential (MEP) and other molecular properties were performed. PMID:23948564

Muthu, S; Elamurugu Porchelvi, E

2013-12-01

190

Quantitative analysis of carbonaceous aerosols using Laser-Induced Breakdown Spectroscopy: A study on mass loading induced plasma matrix effects.  

SciTech Connect

We present results indicating mass loading induced plasma matrix effects on the application of quantitative laser-induced breakdown spectroscopy (LIBS) for estimation of carbon contents in aerosols. An in-house flow-controlled powder-dispersion system generated carbonaceous aerosols with varying bi-modal particle size distributions ({approx} 1 {micro}m and 10 {micro}m median diameters), thereby resulting in a wide mass loading range. For ease of chemical handling and to eliminate toxic effects, common talcum powder was used as our standard aerosol. Normalized atomic species concentrations of C, i.e., (C)/(Si) ratios, were calculated from atomic emission lines of C I (248 nm), Si I (252 nm), and plasma temperatures estimated from a series of Mg I lines. The results show a decrease in (C)/(Si) ratio to about 65% of the initial value as relative mass loadings increased (5.5-100%) due to the increase in number concentrations of larger sized particles ({approx}10 {micro}m median diameter). As a comparison, normalized ratio of (Mg)/(Si) did not exhibit any marked change with increased mass loading. The normalized total absorption of photon flux across the C I (248 nm) spectral line indicated a strong correlation to the percentage decrease in (C)/(Si) ratio. We used an impactor with a cut-off size of around 10 {micro}m diameter to generate mono-modal aerosolized powders ({approx}1 {micro}m median diameter) that had lower relative mass loadings (0.32-0.16%). Similar LIBS analysis on these did not indicate any of the matrix effects. We conclude that for aerosol systems with widely varying mass loadings, quantitative LIBS analysis can be significantly affected by plasma matrix effects, specifically for the C I (248 nm) emission line as noticed in this study. This bears significance for the application of quantitative LIBS in the chemical characterization of all forms of carbonaceous aerosols.

Mukherjee, Dibyendu [ORNL; Cheng, Mengdawn [ORNL

2008-01-01

191

Quantitation of Organics in Supercritical Fluid Aging Experiments Using FTIR Spectroscopy  

SciTech Connect

Aging is a natural process in which hydrophobic organic contaminants slowly accumulate in the mineral pores and organic matter of soils and sediments. Contaminants in aged soils exhibit decreased bioavailability and slow release to the environment. Therefore, aging may have a significant influence on the applicability and effectiveness of remediation strategies (e.g., bioremediation and natural attenuation) and the accuracy of numerical transport models. Previous research in our laboratory has demonstrated that circulating supercritical carbon dioxide can be used to rapidly prepare artificially aged materials for studying slow-release behavior. In this investigation, FTIR spectroscopy was evaluated as a means of monitoring the progress of the aging process in real time. Solvent interferences, measurement sensitivity for selected halocarbons and the influence of temperature and pressure on the FTIR spectra were assessed. Application of this methodology to monitoring the incorporation of carbon tetrachloride into natural soils will be discussed.

Thompson, Christopher J.; Riley, Robert G.; Amonette, James E.; Gassman, Paul L.

2004-03-31

192

[Quantitative analysis of Mn and Si of alloy steels by laser-induced breakdown spectroscopy].  

PubMed

The concentration of Mn and Si in different kinds of steels was determined by laser-induced breakdown spectroscopy (LIBS). The multivariate quadratic nonlinear function was adopted for calibration. Samples including common alloy steels, stainless steels and carbon tool steels were analyzed. The matrix effect was serious because of large difference in compositions of different kinds of steels and strong line overlaps in steel spectra. Therefore, the common calibration methods that only use one analytical line to calibrate the complex chemical compositions of alloy steels will lose much information. The multivariate calibration methods, however, can utilize more information of spectra, successfully reduce the matrix effect and improve the measurement repeatability and accuracy of LIBS. Compared with the common calibration method based on one analytical line, the relative standard deviation was reduced from above 20% to below 10%, and the accuracy was increased by more than 5 times for Mn and more than 6 times for Si. PMID:21322202

Sun, Lan-Xiang; Yu, Hai-Bin; Xin, Yong; Cong, Zhi-Bo

2010-12-01

193

Quantitative Analysis of Microbicide Concentrations in Fluids, Gels and Tissues Using Confocal Raman Spectroscopy  

PubMed Central

Topical vaginal anti-HIV microbicides are an important focus in female-based strategies to prevent the sexual transmission of HIV. Understanding microbicide pharmacokinetics is essential to development, characterization and implementation of efficacious microbicide drug delivery formulations. Current methods to measure drug concentrations in tissue (e.g., LC-MS/MS, liquid chromatography coupled with tandem mass spectrometry) are highly sensitive, but destructive and complex. This project explored the use of confocal Raman spectroscopy to detect microbicide drugs and to measure their local concentrations in fluids, drug delivery gels, and tissues. We evaluated three candidate microbicide drugs: tenofovir, Dapivirine and IQP-0528. Measurements were performed in freshly excised porcine buccal tissue specimens, gel vehicles and fluids using two Horiba Raman microscopes, one of which is confocal. Characteristic spectral peak calibrations for each drug were obtained using serial dilutions in the three matrices. These specific Raman bands demonstrated strong linear concentration dependences in the matrices and were characterized with respect to their unique vibrational signatures. At least one specific Raman feature was identified for each drug as a marker band for detection in tissue. Sensitivity of detection was evaluated in the three matrices. A specific peak was also identified for tenofovir diphosphate, the anti-HIV bioactive product of tenofovir after phosphorylation in host cells. Z-scans of drug concentrations vs. depth in excised tissue specimens, incubated under layers of tenofovir solution in a Transwell assay, showed decreasing concentration with depth from the surface into the tissue. Time-dependent concentration profiles were obtained from tissue samples incubated in the Transwell assay, for times ranging 30 minutes - 6 hours. Calibrations and measurements from tissue permeation studies for tenofovir showed good correlation with gold standard LC-MS/MS data. These results demonstrate that confocal Raman spectroscopy holds promise as a tool for practical, minimally invasive, label-free measurement of microbicide drug concentrations in fluids, gels and tissues. PMID:24386455

Chuchuen, Oranat; Henderson, Marcus H.; Sykes, Craig; Kim, Min Sung; Kashuba, Angela D. M.; Katz, David F.

2013-01-01

194

The effect of photoirradiation on high-yield pulps: spectroscopy and kinetics  

Microsoft Academic Search

Fluorescence, UV-visible reflectance and diffuse reflectance IR Fourier transform spectroscopy were used to study the changes caused by photoirradiation of unbleached, peroxide-bleached and ozone-bleached mechanical and chemimechanical pulps. Irradiations were performed selectively at 350 nm and emission spectra were obtained using the same excitation wavelength. Kinetic curves were obtained by plotting the integrated emission intensity against the irradiation time. Different

Henrik Tylli; Ingegerd Forsskåhl; Carola Olkkonen

1995-01-01

195

(Compensation for peak shifts and variable background responses in fluorescence spectroscopy)  

SciTech Connect

In the past year, we have made significant progress in several areas. Most of our research has focused on improvements in data analysis methodologies for fluorescence spectroscopic detection in thin-layer and high performance liquid chromatographies, although some experiments have extended the applicability of uv-visible detection methods on thin-layer chromatographic plates. One area of research has focused on the development and evaluation of methods for background correction in fluorescence spectroscopy.

Rutan, S.C.

1989-01-01

196

Surface enhanced Raman spectroscopy as a new spectral technique for quantitative detection of metal ions  

NASA Astrophysics Data System (ADS)

Four newly synthesized poly (propylene amine) dendrimers from first and second generation modified with 1,8-naphthalimide units in the dendrimer periphery have been investigated as ligands for the detection of heavy metal ions (Al3+, Sb2+, As2+, Cd2+ and Pb2+) by surface-enhanced Raman spectroscopy. Calibration curves were established for all metal ions between the concentration ranges of  1 x 10-6 to 5 x 10-4 M. It has been shown that these dendrimers can be coordinated, especially with different metal ions. Using dendrimer molecules and silver colloids at the same time allowed us to obtain an SERS signal from the abovementioned metal ions at very low concentrations. Principle component analysis (PCA) analysis was also applied to the collected SERS data. Four differentPCA models were developed to accomplish the discrimination of five metal ions, which interacted with each of the four dendrimer molecules, separately. A detailed investigation was performed in the present study to provide the basis of a new approach for heavy metal detection.

Temiz, Havva Tumay; Boyaci, Ismail Hakki; Grabchev, Ivo; Tamer, Ugur

2013-12-01

197

Quantitative evaluation of noncovalent interactions between glyphosate and dissolved humic substances by NMR spectroscopy.  

PubMed

Interactions of glyphosate (N-phosphonomethylglycine) herbicide (GLY) with soluble fulvic acids (FAs) and humic acids (HAs) at pH 5.2 and 7 were studied by (1)H and (31)P NMR spectroscopy. Increasing concentrations of soluble humic matter determined broadening and chemical shift drifts of proton and phosphorus GLY signals, thereby indicating the occurrence of weak interactions between GLY and humic superstructures. Binding was larger for FAs and pH 5.2 than for HAs and pH 7, thus suggesting formation of hydrogen bonds between GLY carboxyl and phosphonate groups and protonated oxygen functions in humic matter. Changes in relaxation and correlation times of (1)H and (31)P signals and saturation transfer difference NMR experiments confirmed the noncovalent nature of GLY-humic interactions. Diffusion-ordered NMR spectra allowed calculation of the glyphosate fraction bound to humic superstructures and association constants (K(a)) and Gibbs free energies of transfer for GLY-humic complex formation at both pH values. These values showed that noncovalent interactions occurred most effectively with FAs and at pH 5.2. Our findings indicated that glyphosate may spontaneously and significantly bind to soluble humic matter by noncovalent interactions at slightly acidic pH and, thus, potentially pollute natural water bodies by moving through soil profiles in complexes with dissolved humus. PMID:22591574

Mazzei, Pierluigi; Piccolo, Alessandro

2012-06-01

198

Fast quantitative determination of microbial rhamnolipids from cultivation broths by ATR-FTIR Spectroscopy  

PubMed Central

Background Vibrational spectroscopic techniques are becoming increasingly important and popular because they have the potential to provide rapid and convenient solutions to routine analytical problems. Using these techniques, a variety of substances can be characterized, identified and also quantified rapidly. Results The rapid ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy) in time technique has been applied, which is suitable to quantify the concentrations of microbial rhamnolipids in a typical cultivation process. While the usually applied HPLC analysis requires an extensive and time consuming multi step extraction protocol for sample preparation, the ATR-FTIR-method allows the quantification of the rhamnolipids within 20 minutes. Accuracies between 0.5 g/l – 2.1 g/l for the different analytes were determined by cross validation of the calibration set. Even better accuracies between 0.28 g/l – 0.59 g/l were found for independent test samples of an arbitrarily selected cultivation. Conclusion ATR-FTIR was found to be suitable for the rapid analysis of rhamnolipids in a biotechnological process with good reproducibility in sample determination and sufficient accuracy. An improvement in accuracy through continuous expansion and validation of the reference spectra set seems very likely. PMID:18840269

Leitermann, Frank; Syldatk, Christoph; Hausmann, Rudolf

2008-01-01

199

Quantitative determinations of levofloxacin and rifampicin in pharmaceutical and urine samples using nuclear magnetic resonance spectroscopy  

NASA Astrophysics Data System (ADS)

Rapid, specific and simple methods for determining levofloxacin and rifampicin antibiotic drugs in pharmaceutical and human urine samples were developed. The methods are based on 1H NMR spectroscopy using maleic acid as an internal standard and DMSO-d6 as NMR solvent. Integration of NMR signals at 8.9 and 8.2 ppm were, respectively, used for calculating the concentration of levofloxacin and rifampicin drugs per unit dose. Maleic acid signal at 6.2 ppm was used as the reference signal. Recoveries of (97.0-99.4) ± 0.5 and (98.3-99.7) ± 1.08% were obtained for pure levofloxacin and rifampicin, respectively. Corresponding recoveries of 98.5-100.3 and 96.8-100.0 were, respectively, obtained in pharmaceutical capsules and urine samples. Relative standard deviations (R.S.D.) values ?2.7 were obtained for analyzed drugs in pure, pharmaceutical and urine samples. Statistical Student's t-test gave t-values ?2.87 indicating insignificant difference between the real and the experimental values at the 95% confidence level. F-test revealed insignificant difference in precisions between the developed NMR methods and each of fluorimetric and HPLC methods for analyzing levofloxacin and rifampicin.

Salem, A. A.; Mossa, H. A.; Barsoum, B. N.

2005-11-01

200

Surface enhanced Raman spectroscopy as a new spectral technique for quantitative detection of metal ions.  

PubMed

Four newly synthesized poly (propylene amine) dendrimers from first and second generation modified with 1,8-naphthalimide units in the dendrimer periphery have been investigated as ligands for the detection of heavy metal ions (Al(3+), Sb(2+), As(2+), Cd(2+) and Pb(2+)) by surface-enhanced Raman spectroscopy. Calibration curves were established for all metal ions between the concentration ranges of 1 x 10(-6) to 5 x 10(-4) M. It has been shown that these dendrimers can be coordinated, especially with different metal ions. Using dendrimer molecules and silver colloids at the same time allowed us to obtain an SERS signal from the abovementioned metal ions at very low concentrations. Principle component analysis (PCA) analysis was also applied to the collected SERS data. Four different PCA models were developed to accomplish the discrimination of five metal ions, which interacted with each of the four dendrimer molecules, separately. A detailed investigation was performed in the present study to provide the basis of a new approach for heavy metal detection. PMID:23973576

Temiz, Havva Tumay; Boyaci, Ismail Hakki; Grabchev, Ivo; Tamer, Ugur

2013-12-01

201

Heterogeneous nanostructures for plasmonic interaction with luminescence and quantitative surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

NIR-to-visible up-conversion nanomaterials have been investigated in many promising applications including nextgeneration displays, solar cells, and biological labels. When doped with different trivalent lanthanide ions, NaYF4 nanoparticles can produce up-converted emission from visible to infra-red wavelengths. However, the quantum yield of this class of materials is low. Noble metals in the vicinity of the phosphor can increase the phosphorescence by local field enhancement due to plasmonic resonances, and by modification of the radiative rate of the phosphor. Most previous studies have investigated the phenomenon by placing nanophosphors onto a metal substrate, or by fabrication of nano structures with spacers such as polymers, dielectric materials (silica). By contrast, we have studied the interaction between the luminescence and the surface plasmon using a core-shell type nanostructure where a uniform shell of silver is shown to grown on doped-NaYF4 nanophosphors by Ostwald ripening. We further demonstrate the proximity effect of metal-enhanced luminescence by exciting an undoped NaYF4 shell. The result shows a significant synergistic enhancement of up-conversion luminescence due to the active shell as spacer layer. In addition, we have shown this novel nanostructure may be useful in surface-enhanced Raman spectroscopy (SERS).

Das, Gautom K.; Sudheendra, L.; Kennedy, Ian M.

2014-03-01

202

Quantitative determination of acetylsalicylic acid and acetaminophen in tablets by FT-Raman spectroscopy.  

PubMed

A procedure for quantitative determination of acetylsalicylic acid and acetaminophen in pharmaceuticals by PLS (partial least squares) and PCR (principal component regression) treatment of FT (Fourier transform)-Raman spectroscopic data is proposed. The proposed method was tested on powdered samples. Three chemometric models were built: the first, for samples consisting of an active substance diluted by lactose, starch and talc; the second, in which a simple inorganic salt was applied as an internal standard and additions were not taken into account; and the third, in which a model was constructed for a commercial pharmaceutical, where all constituents of the tablet were known. By utilising selected spectral ranges and by changing the chemometric conditions it is possible to carry out fast and precise analysis of the active component content in medicines on the basis of the simplified chemometric models. The proposed method was tested on five commercial tablets. The results were compared with data obtained by intensity ratio and pharmacopoeial methods. To appraise the quality of the models, the relative standard error of predictions (RSEPs) were calculated for calibration and prediction data sets. These were 0.7-2.0% and 0.8-2.3%, respectively, for the different PLS models. Application of these models to the Raman spectra of commercial tablets containing acetylsalicylic acid gave RSEP values of 1.3-2.0% and a mean accuracy of 1.2-1.7% with a standard deviation of 0.6-1.2%. PMID:11827382

Szostak, Roman; Mazurek, Sylwester

2002-01-01

203

Vibrational Spectroscopy and Chemometrics for Rapid, Quantitative Analysis of Bitter Acids in Hops (Humulus lupulus).  

PubMed

Hops, Humulus lupulus, are grown worldwide for use in the brewing industry to impart characteristic flavor and aroma to finished beer. Breeders produce many varietal crosses with the aim of improving and diversifying commercial hops varieties. The large number of crosses critical to a successful breeding program imposes high demands on the supporting chemical analytical laboratories. With the aim of reducing the analysis time associated with hops breeding, quantitative partial least-squares regression (PLS-R) models have been produced, relating reference data acquired by the industrial standard HPLC and UV methods, to vibrational spectra of the same, chemically diverse hops sample set. These models, produced from rapidly acquired infrared (IR), near-infrared (NIR), and Raman spectra, were appraised using standard statistical metrics. Results demonstrated that all three spectroscopic methods could be used for screening hops for ?-acid, total bitter acids, and cohumulone concentrations in powdered hops. Models generated from Raman and IR spectra also showed potential for use in screening hops varieties for xanthohumol concentrations. NIR analysis was performed using both a standard benchtop spectrometer and a portable NIR spectrometer, with comparable results obtained by both instruments. Finally, some important vibrational features of cohumulone, colupulone, and xanthohumol were assigned using DFT calculations, which allow more insightful interpretation of PLS-R latent variable plots. PMID:25485767

Killeen, Daniel P; Andersen, David H; Beatson, Ron A; Gordon, Keith C; Perry, Nigel B

2014-12-31

204

Qualitative and quantitative determination of human biomarkers by laser photoacoustic spectroscopy methods  

NASA Astrophysics Data System (ADS)

The hypothesis that blood, urine and other body fluids and tissues can be sampled and analyzed to produce clinical information for disease diagnosis or therapy monitoring is the basis of modern clinical diagnosis and medical practice. The analysis of breath air has major advantages because it is a non-invasive method, represents minimal risk to personnel collecting the samples and can be often sampled. Breath air samples from the human subjects were collected using aluminized bags from QuinTron and analyzed using the laser photoacoustic spectroscopy (LPAS) technique. LPAS is used to detect traces of ethylene in breath air resulting from lipid peroxidation in lung epithelium following the radiotherapy and also traces of ammonia from patients subjected to hemodialysis for treatment of renal failure. In the case of patients affected by cancer and treated by external radiotherapy, all measurements were done at 10P(14) CO2 laser line, where the ethylene absorption coefficient has the largest value (30.4 cm-1 atm-1), whereas for patients affected by renal failure and treated by standard dialysis, all measurements were performed at 9R(30) CO2 laser line, where the ammonia absorption coefficient has the maximum value of 57 cm-1 atm-1. The levels of ethylene and ammonia in exhaled air, from patients with cancer and renal failure, respectively, were measured and compared with breath air contents from healthy humans. Human gas biomarkers were measured at sub-ppb (parts per billion) concentration sensitivities. It has been demonstrated that LPAS technique will play an important role in the future of exhaled breath air analysis. The key attributes of this technique are sensitivity, selectivity, fast and real time response, as well as its simplicity.

Popa, C.; Bratu, A. M.; Matei, C.; Cernat, R.; Popescu, A.; Dumitras, D. C.

2011-07-01

205

Quantitation of ten 30S ribosomal assembly intermediates using fluorescence triple correlation spectroscopy  

PubMed Central

The self-assembly of bacterial 30S ribosomes involves a large number of RNA folding and RNA-protein binding steps. The sequence of steps determines the overall assembly mechanism and the structure of the mechanism has ramifications for the robustness of biogenesis and resilience against kinetic traps. Thermodynamic interdependencies of protein binding inferred from omission-reconstitution experiments are thought to preclude certain assembly pathways and thus enforce ordered assembly, but this concept is at odds with kinetic data suggesting a more parallel assembly landscape. A major challenge is deconvolution of the statistical distribution of intermediates that are populated during assembly at high concentrations approaching in vivo assembly conditions. To specifically resolve the intermediates formed by binding of three ribosomal proteins to the full length 16S rRNA, we introduce Fluorescence Triple-Correlation Spectroscopy (F3CS). F3CS identifies specific ternary complexes by detecting coincident fluctuations in three-color fluorescence data. Triple correlation integrals quantify concentrations and diffusion kinetics of triply labeled species, and F3CS data can be fit alongside auto-correlation and cross-correlation data to quantify the populations of 10 specific ribosome assembly intermediates. The distribution of intermediates generated by binding three ribosomal proteins to the entire native 16S rRNA included significant populations of species that were not previously thought to be thermodynamically accessible, questioning the current interpretation of the classic omission-reconstitution experiments. F3CS is a general approach for analyzing assembly and function of macromolecular complexes, especially those too large for traditional biophysical methods. PMID:22869699

Ridgeway, William K.; Millar, David P.; Williamson, James R.

2012-01-01

206

Highly-accelerated quantitative 2D and 3D localized spectroscopy with linear algebraic modeling (SLAM) and sensitivity encoding  

PubMed Central

Noninvasive magnetic resonance spectroscopy (MRS) with chemical shift imaging (CSI) provides valuable metabolic information for research and clinical studies, but is often limited by long scan times. Recently, spectroscopy with linear algebraic modeling (SLAM) was shown to provide compartment-averaged spectra resolved in one spatial dimension with many-fold reductions in scan-time. This was achieved using a small subset of the CSI phase-encoding steps from central image k-space that maximized the signal-to-noise ratio. Here, SLAM is extended to two- and three-dimensions (2D, 3D). In addition, SLAM is combined with sensitivity-encoded (SENSE) parallel imaging techniques, enabling the replacement of even more CSI phase-encoding steps to further accelerate scan-speed. A modified SLAM reconstruction algorithm is introduced that significantly reduces the effects of signal nonuniformity within compartments. Finally, main-field inhomogeneity corrections are provided, analogous to CSI. These methods are all tested on brain proton MRS data from a total of 24 patients with brain tumors, and in a human cardiac phosphorus 3D SLAM study at 3T. Acceleration factors of up to 120-fold versus CSI are demonstrated, including speed-up factors of 5-fold relative to already-accelerated SENSE CSI. Brain metabolites are quantified in SLAM and SENSE SLAM spectra and found to be indistinguishable from CSI measures from the same compartments. The modified reconstruction algorithm demonstrated immunity to maladjusted segmentation and errors from signal heterogeneity in brain data. In conclusion, SLAM demonstrates the potential to supplant CSI in studies requiring compartment-average spectra or large volume coverage, by dramatically reducing scan-time while providing essentially the same quantitative results. PMID:24188921

Zhang, Yi; Gabr, Refaat E.; Zhou, Jinyuan; Weiss, Robert G.; Bottomley, Paul A.

2013-01-01

207

Quantitative analysis of double-stranded DNA amplified by a polymerase chain reaction employing surface-enhanced Raman spectroscopy.  

PubMed

Surface-enhanced Raman spectroscopy (SERS) was utilized for the quantitative analysis of double-stranded (ds) DNA amplified by a polymerase chain reaction (PCR). 4?, 6-Diamidino-2-phenylindole dihydrochloride (DAPI), which intercalates into ds-DNA but does not form a complex with single-stranded (ss) DNA, was added to a DNA solution after amplification by PCR. When the solution was mixed, including ds-DNA-DAPI complexes and free DAPI with silver colloid sol, only free DAPI was adsorbed on the colloid surface. The dye on the colloid gave very intense SERS signals with excitation at 514.5 nm, whereas DAPI engaging in the intercalation with ds-DNA did not show any SERS signal. The SERS spectrum of DAPI on the colloid showed a strong band at 1610 cm(-1) due to the C?N stretching mode, and a linear relationship was observed between the peak intensity of the C?N stretching band and the concentration of free DAPI. Therefore one can determine the concentration of free DAPI by the SERS measurement. The more ds-DNA there is in the solution, the less free DAPI there is. Thus it is possible to quantitatively analyze the ds-DNA amplified by PCR indirectly by using SERS. The correlation coefficient between the peak intensity of the C?N stretching band and the concentration of ds-DNA amplified by PCR was calculated to be 0.988 for a concentration range from 0.1 to 1.3 mg/ml. PMID:18268650

Dou, X; Takama, T; Yamaguchi, Y; Hirai, K; Yamamoto, H; Doi, S; Ozaki, Y

1998-02-01

208

Quantitative analysis of sulfur functional groups in natural organic matter by XANES spectroscopy  

NASA Astrophysics Data System (ADS)

Two new approaches to quantify sulfur functionalities in natural organic matter from S K-edge XANES spectroscopy are presented. In the first, the K-edge spectrum is decomposed into Gaussian and two arctangent functions, as in the usual Gaussian curve fitting (GCF) method, but the applicability of the model is improved by a rigorous simulation procedure that constrains the model-fit to converge toward chemically and physically realistic values. Fractions of each type of functionality are obtained after spectral decomposition by correcting Gaussian areas for the change in X-ray absorption cross-section with increasing oxidation state. This correction is made using published calibration curves and a new curve obtained in this study. Calibration-induced errors, inherent to the choice of a particular curve, are typically lower than 5% of total sulfur for oxidized species (e.g., sulfate), may reach 10% for organic reduced sulfur, and may be as high as 30-40% for inorganic reduced sulfur. A generic curve, which reduces the calibration-induced uncertainty by a factor of two on data collected to avoid X-ray overabsorption, is derived. In the second analytical scheme, the K-edge spectrum is partitioned into a weighted sum of component species, as in the usual linear combination fitting (LCF) method, but is fit to an extended database of reference spectra under the constraint of non-negativity in the loadings (Combo fit). The fraction of each sulfur functionality is taken as the sum of all positive fractions of references with similar oxidation state of sulfur. The two proposed methods are applied to eight humic and fulvic acids from the International Humic Substances Society (IHSS). The nature and fractions of sulfur functionalities obtained by the two analytical approaches are consistent with each other. The accuracy of the derived values, expressed as the difference in values of a fraction obtained on the same material by the two independent methods, is on average 4.5 ± 3.0% of total sulfur for exocyclic reduced sulfur, 4.1 ± 2.1% for heterocyclic reduced sulfur, and 1.6 ± 1.4% for sulfate. Total reduced sulfur has a better accuracy of estimation (2.4 ± 1.6%) than either exocyclic and heterocyclic sulfur, because the errors on the two reduced pools have opposite sign. Experimental difficulties and uncertainties of the results associated with the analysis of concentrated and heterogeneous samples are discussed. The spectra of the IHSS materials and the reference compounds are made available as an open source for interlaboratory testing.

Manceau, Alain; Nagy, Kathryn L.

2012-12-01

209

Quantitative antimony speciation in shooting-range soils by EXAFS spectroscopy  

NASA Astrophysics Data System (ADS)

The Sb speciation in soil samples from Swiss shooting ranges was determined using Sb K-edge X-ray absorption spectroscopy (XAS) and advanced statistical data analysis methods (iterative transformation factor analysis, ITFA). The XAS analysis was supported by a spectral data set of 13 Sb minerals and 4 sorption complexes. In spite of a high variability in geology, soil pH (3.1-7.5), Sb concentrations (1000-17,000 mg/kg) and shooting-range history, only two Sb species were identified. In the first species, Sb is surrounded solely by other Sb atoms at radial distances of 2.90, 3.35, 4.30 and 4.51 Å, indicative of metallic Sb(0). While part of this Sb(0) may be hosted by unweathered bullet fragments consisting of PbSb alloy, Pb L III-edge XAS of the soil with the highest fraction (0.75) of Sb(0) showed no metallic Pb, but only Pb 2+ bound to soil organic matter. This suggests a preferential oxidation of Pb in the alloy, driven by the higher standard reduction potential of Sb. In the second species, Sb is coordinated to 6 O-atoms at a distance of 1.98 Å, indicative of Sb(V). This oxidation state is further supported by an edge energy of 30,496-30,497 eV for the soil samples with <10% Sb(0). Iron atoms at radial distances of 3.10 and 3.56 Å from Sb atoms are in line with edge-sharing and bidentate corner-sharing linkages between Sb(O,OH) 6 and Fe(O,OH) 6 octahedra. While similar structural units exist in tripuhyite, the absence of Sb neighbors contradicts formation of this Fe antimonate. Hence the second species most likely consists of inner-sphere sorption complexes on Fe oxides, with edge and corner-sharing configuration occurring simultaneously. This pentavalent Sb species was present in all samples, suggesting that it is the prevailing species after weathering of metallic Sb(0) in oxic soils. No indication of Sb(III) was found.

Scheinost, Andreas C.; Rossberg, Andre; Vantelon, Delphine; Xifra, Irene; Kretzschmar, Ruben; Leuz, Ann-Kathrin; Funke, Harald; Johnson, C. Annette

2006-07-01

210

Syntheses, crystal structures and UV-visible absorption properties of five metal-organic frameworks constructed from terphenyl-2,5,2',5'-tetracarboxylic acid and bis(imidazole) bridging ligands.  

PubMed

The solvothermal reactions of terphenyl-2,5,2',5'-tetracarboxylic acid (H4tptc) and transition metal cations (Ni(II), Mn(II)) afford five novel coordination polymers (CPs) in the presence of four bis(imidazole) bridging ligands (1,3-bimb = 1,3-bis(imidazol-1-ylmethyl)benzene, 1,4-bmib = 1,4-bis(2-methylimidazol-1-ylmethyl)benzene, 4,4'-bibp = 4,4'-bis(imidazol-1-yl)biphenyl, 4,4'-bimbp = 4,4'-bis(imidazol-1-ylmethyl)biphenyl), namely, [M(tptc)(0.5)(1,3-bimb)(H2O)]n (M = Ni for 1, Mn for 2), {[Ni(tptc)(0.5)(1,4-bmib)]·0.25H2O}n (3), {[Ni(tptc)(0.5)(4,4'-bibp)2(H2O)]·2H2O}n (4) and {[Ni(tptc)(0.5)(4,4'-bimbp)(1.5)(H2O)]·H2O}n (5). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Complexes 1 and 2 are isomorphous and exhibit a 3D (3,4)-connected tfi framework with the point Schläfli symbol of (4·6(2))(4·6(6)·8(3)). Complex 3 shows an unprecedented 3D (4,4)-connected framework with the point Schläfli symbol of (4·6(4)·8(2))2(4(2)·8(4)). Complex 4 displays a novel 2D self-catenating 5-connected network with the Schläfli symbol of (4(6)·6(4)) based on three interpenetrating 4(4)-sql subnets. Complex 5 features a 2D 3-connected 6(3)-hcb network built from interesting chains with loops. To the best of our knowledge, the 3D (4,4)-connected (4·6(4)·8(2))2(4(2)·8(4)) host-framework of 3 and 2D self-catenating 5-connected (4(6)·6(4)) network of 4 have never been documented to date. Moreover, the UV-Visible absorption spectra of complexes 1-5 have been investigated. PMID:24638083

Fan, Liming; Zhang, Xiutang; Zhang, Wei; Ding, Yuanshuai; Fan, Weiliu; Sun, Liming; Pang, Yue; Zhao, Xian

2014-05-14

211

La Spectroscopie Raman (SR) : un nouvel outil adapté au Contrôle de Qualité Analytique des préparations injectables en milieu de soins. Comparaison de la SR aux techniques CLHP et UV\\/visible-IRTF appliquée à la classe des anthracyclines en cancérologie  

Microsoft Academic Search

The study compares the performances of three analytical methods devoted to Analytical Quality Control (AQC) of therapeutic solutions formed into care environment, we are talking about Therapeutics ObjectsTN (TOsTN). We explored the pharmacological model of two widely used anthracyclines i.e. adriamycin and epirubicin. We compared the performance of the HPLC vs two vibrational spectroscopic techniques: a tandem UV\\/Vis-FTIR one hand

P. Bourget; A. Amin; A. Moriceau; B. Cassard; F. Vidal; R. Clement

212

A method for quantitative mapping of thick oil spills using imaging spectroscopy  

USGS Publications Warehouse

In response to the Deepwater Horizon oil spill in the Gulf of Mexico, a method of near-infrared imaging spectroscopic analysis was developed to map the locations of thick oil floating on water. Specifically, this method can be used to derive, in each image pixel, the oil-to-water ratio in oil emulsions, the sub-pixel areal fraction, and its thicknesses and volume within the limits of light penetration into the oil (up to a few millimeters). The method uses the shape of near-infrared (NIR) absorption features and the variations in the spectral continuum due to organic compounds found in oil to identify different oil chemistries, including its weathering state and thickness. The method is insensitive to complicating conditions such as moderate aerosol scattering and reflectance level changes from other conditions, including moderate sun glint. Data for this analysis were collected by the NASA Airborne Visual Infrared Imaging Spectrometer (AVIRIS) instrument, which was flown over the oil spill on May 17, 2010. Because of the large extent of the spill, AVIRIS flight lines could cover only a portion of the spill on this relatively calm, nearly cloud-free day. Derived lower limits for oil volumes within the top few millimeters of the ocean surface directly probed with the near-infrared light detected in the AVIRIS scenes were 19,000 (conservative assumptions) to 34,000 (aggressive assumptions) barrels of oil. AVIRIS covered about 30 percent of the core spill area, which consisted of emulsion plumes and oil sheens. Areas of oil sheen but lacking oil emulsion plumes outside of the core spill were not evaluated for oil volume in this study. If the core spill areas not covered by flight lines contained similar amounts of oil and oil-water emulsions, then extrapolation to the entire core spill area defined by a MODIS (Terra) image collected on the same day indicates a minimum of 66,000 to 120,000 barrels of oil was floating on the surface. These estimates are preliminary and subject to revision pending further analysis. Based on laboratory measurements, near-infrared (NIR) photons penetrate only a few millimeters into oil-water emulsions. As such, the oil volumes derived with this method are lower limits. Further, the detection is only of thick surface oil and does not include sheens, underwater oil, or oil that had already washed onto beaches and wetlands, oil that had been burned or evaporated as of May 17. Because NIR light penetration within emulsions is limited, and having made field observations that oil emulsions sometimes exceeded 20 millimeters in thickness, we estimate that the volume of oil, including oil thicker than can be probed in the AVIRIS imagery, is possibly as high as 150,000 barrels in the AVIRIS scenes. When this value is projected to the entire spill, it gives a volume of about 500,000 barrels for thick oil remaining on the sea surface as of May 17. AVIRIS data cannot be used to confirm this higher volume, and additional field work including more in-situ measurements of oil thickness would be required to confirm this higher oil volume. Both the directly detected minimum range of oil volume, and the higher possible volume projection for oil thicker than can be probed with NIR spectroscopy imply a significantly higher total volume of oil relative to that implied by the early NOAA (National Oceanic and Atmospheric Administration) estimate of 5,000 barrels per day reported on their Web site.

Clark, Roger N.; Swayze, Gregg A.; Leifer, Ira; Livo, K. Eric; Kokaly, Raymond; Hoefen, Todd; Lundeen, Sarah; Eastwood, Michael; Green, Robert O.; Pearson, Neil; Sarture, Charles; McCubbin, Ian; Roberts, Dar; Bradley, Eliza; Steele, Denis; Ryan, Thomas; Dominguez, Roseanne; The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Team

2010-01-01

213

Qualitative and quantitative analysis of CO2 and CH4 dissolved in water and seawater using laser Raman spectroscopy.  

PubMed

Laboratory experiments have been performed using laser Raman spectroscopy to analyze carbon dioxide (CO(2)) and methane (CH(4)) dissolved in water and seawater. Dissolved CO(2) is characterized by bands at approximately 1275 and 1382 Deltacm(-1). Dissolved CH(4) is characterized by a dominant band at approximately 2911 Deltacm(-1). The laboratory instrumentation used for this work is equivalent to the sea-going Raman instrument, DORISS (Deep Ocean Raman In Situ Spectrometer). Limits of quantification and calibration curves were determined for each species. The limits of quantification are approximately 10 mM for CO(2) and approximately 4 mM for CH(4). A ratio technique is used to obtain quantitative information from Raman spectra: the gas bands are referenced to the O-H stretching band of water. The calibration curves relating band height ratios to gas concentration are linear and valid for a range of temperatures, pressures, and salinities. Current instrumentation is capable of measuring the highest dissolved gas concentration observed in end-member hydrothermal fluids. Further development work is needed to improve sensitivity and optimize operational configurations. PMID:20615296

White, Sheri N

2010-07-01

214

In vivo quantitative near-infrared spectroscopy in skeletal muscle and bone during rest and isometric exercise  

NASA Astrophysics Data System (ADS)

In this study quantitative near-infrared-spectroscopy (NIRS) was investigated as a potential tool to measure local O2 consumption (mVO2) in human bone (tibia) in comparison with muscle (musculus tibialis anterior). Both tissues were examined at rest and during 80% maximum voluntary isometric muscle contraction. Fifteen subjects were tested. Local variations in oxy-hemoglobin (O2Hb), desoxy-hemoglobin (HHb), and total hemoglobin (tHb) were investigated with a continuously operating NIRS system. mVO2 was determined in phases of applied arterial occlusion. At rest mVO2 was five times higher in muscle than in bone. However, both mVO2 values showed a distinct correlation with skin-fold thickness. At rest and only in bone we recorded a periodical variation of O2Hb. HHb was almost constant. This variation of O2Hb and the resulting variation in tHb indicated chances in blood volume, which are not compatible with the solid nature of bone. During muscle contraction, mVO2 in muscle increased about twenty fold. As expected, mVO2 in bone did not significantly increase during muscle contraction. In conclusion, NIRS was confirmed as a valid method to determine the excess mVO2 in muscle during contraction. For mVO2 measurements in bone more sophisticated localization techniques are required to separate the effects derived from bone and skin.

Klasing, Manfred; Zange, Jochen

2003-10-01

215

Remote Quantitative Analysis of Minerals Based on Multispectral Line-Calibrated Laser-Induced Breakdown Spectroscopy (LIBS).  

PubMed

Laser-induced breakdown spectroscopy (LIBS) is a feasible remote sensing technique used for mineral analysis in some unapproachable places where in situ probing is needed, such as analysis of radioactive elements in a nuclear leak or the detection of elemental compositions and contents of minerals on planetary and lunar surfaces. Here a compact custom 15 m focus optical component, combining a six times beam expander with a telescope, has been built, with which the laser beam of a 1064 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is focused on remote minerals. The excited LIBS signals that reveal the elemental compositions of minerals are collected by another compact single lens?based signal acquisition system. In our remote LIBS investigations, the LIBS spectra of an unknown ore have been detected, from which the metal compositions are obtained. In addition, a multi-spectral line calibration (MSLC) method is proposed for the quantitative analysis of elements. The feasibility of the MSLC and its superiority over a single-wavelength determination have been confirmed by comparison with traditional chemical analysis of the copper content in the ore. PMID:25198122

2014-10-01

216

Rate-equation model for quantitative concentration measurements in flames with picosecond pump-probe absorption spectroscopy.  

PubMed

Measurement of radical concentrations is important in understanding the chemical kinetics involved in combustion. Application of optical techniques allows for the nonintrusive determination of specific radical concentrations. One of the most challenging problems for investigators is to obtain flame data that are independent of the collisional environment. We seek to obviate this difficulty by the use of picosecond pump-probe absorption spectroscopy. A picosecond pump-probe absorption model is developed by rate-equation analysis. Implications are discussed for a laser-pulse width that is much smaller than the excited-state lifetime of the absorbing atom or molecule. The possibility of quantitative, quenching-independent concentration measurements is discussed, and detection limits for atomic sodium and the hydroxyl radical are estimated. For a three-level absorber-emitter, the model leads to a novel pump-probe strategy, called dual-beam asynchronous optical sampling, that can be used to obtain both the electronic quenching-rate coefficient and the doublet mixing-rate coefficient during a single measurement. We discuss the successful demonstration of the technique in a companion paper [Appl. Opt. 34, XXX (1995)]. PMID:21037640

Fiechtner, G J; King, G B; Laurendeau, N M

1995-02-20

217

Towards a non-invasive quantitative analysis of the organic components in museum objects varnishes by vibrational spectroscopies: methodological approach.  

PubMed

The compositions of ancient varnishes are mainly determined destructively by separation methods coupled to mass spectrometry. In this study, a methodology for non-invasive quantitative analyses of varnishes by vibrational spectroscopies is proposed. For that, experimental simplified varnishes of colophony and linseed oil were prepared according to 18th century traditional recipes with an increasing mass concentration ratio of colophony/linseed oil. FT-Raman and IR analyses using ATR and non-invasive reflectance modes were done on the "pure" materials and on the different mixtures. Then, a new approach involving spectral decomposition calculation was developed considering the mixture spectra as a linear combination of the pure materials ones, and giving a relative amount of each component. Specific spectral regions were treated and the obtained results show a good accuracy between the prepared and calculated amounts of the two compounds. We were thus able to detect and quantify from 10% to 50% of colophony in linseed oil using non-invasive techniques that can also be conducted in situ with portable instruments when it comes to museum varnished objects and artifacts. PMID:25127604

Daher, Céline; Pimenta, Vanessa; Bellot-Gurlet, Ludovic

2014-11-01

218

Surface-Enhanced Raman Spectroscopy Based Quantitative Bioassay on Aptamer-Functionalized Nanopillars Using Large-Area Raman Mapping  

PubMed Central

Surface-enhanced Raman spectroscopy (SERS) has been used in a variety of biological applications due to its high sensitivity and specificity. Here, we report a SERS-based biosensing approach for quantitative detection of biomolecules. A SERS substrate bearing gold-decorated silicon nanopillars is functionalized with aptamers for sensitive and specific detection of target molecules. In this study, TAMRA-labeled vasopressin molecules in the picomolar regime (1 pM to 1 nM) are specifically captured by aptamers on the nanostructured SERS substrate and monitored by using an automated SERS signal mapping technique. From the experimental results, we show concentration-dependent SERS responses in the picomolar range by integrating SERS signal intensities over a scanning area. It is also noted that our signal mapping approach significantly improves statistical reproducibility and accounts for spot-to-spot variation in conventional SERS quantification. Furthermore, we have developed an analytical model capable of predicting experimental intensity distributions on the substrates for reliable quantification of biomolecules. Lastly, we have calculated the minimum needed area of Raman mapping for efficient and reliable analysis of each measurement. Combining our SERS mapping analysis with an aptamer-functionalized nanopillar substrate is found to be extremely efficient for detection of low-abundance biomolecules. PMID:23713574

Yang, Jaeyoung; Palla, Mirko; Bosco, Filippo Giacomo; Rindzevicius, Tomas; Alstrøm, Tommy Sonne; Schmidt, Michael Stenbæk; Boisen, Anja; Ju, Jingyue; Lin, Qiao

2013-01-01

219

Java-based graphical user interface for MRUI, a software package for quantitation of in vivo/medical magnetic resonance spectroscopy signals.  

PubMed

This article describes a Java-based graphical user interface for the magnetic resonance user interface (MRUI) quantitation package. This package allows MR spectroscopists to easily perform time-domain analysis of in vivo/medical MR spectroscopy data. We have found that the Java programming language is very well suited for developing highly interactive graphical software applications such as the MRUI system. We also have established that MR quantitation algorithms, programmed in the past in other languages, can easily be embedded into the Java-based MRUI by using the Java native interface (JNI). PMID:11334636

Naressi, A; Couturier, C; Castang, I; de Beer, R; Graveron-Demilly, D

2001-07-01

220

Quantitative Applications of Deep-Sea Raman Spectroscopy: Geochemistry of 1,4- thioxane in sea water  

NASA Astrophysics Data System (ADS)

We have developed quantitative Raman spectroscopic techniques for the novel detection of dissolved species in sea water to determine their fundamental properties. In this example we use a field-deployable Raman system to determine the solubility of 1,4-thioxane (TO) in sea water as 0.65 to 0.63 mol/kg H2O between 4.5°C and 25.0°C (which varies greatly from an earlier report of 2.75 mol/kg H2O), and to assess the conditions under which it may form a hydrate. TO is of unusual environmental interest as a breakdown product of the chemical weapon mustard gas, and thus development of non-contact field- deployable sensing techniques is highly desirable. Raman spectroscopy has typically been considered as only a qualitative technique due to the complexity of the optical path and the substantial changes in components between different instruments. We show here that by self-referencing to the ubiquitous water peaks (the water ?2 mode from 1500 to 1800 cm-1) we can derive quantitative information with a precision of ± 4%, and provide essential new information. The long-term fate of large quantities of chemical weapons disposed of in the ocean some 50 years ago is poorly known. Part of this lacking knowledge can be attributed to the hazards associated with the direct study of these materials leaving ocean scientists vulnerable when sampling in inadequately marked sites. Mustard gas (1,1'-thiobis[2-chloroethane]) represents the largest tonnage of material disposed of until the 1972 London Convention banned such activities. Thus there is strong interest in determining the fate and lifetime of these materials, their decomposition products, and the extent of the affected zones. We have earlier shown that TO forms a hydrate with a help-gas, such as methane or hydrogen sulfide, and that the temperature, pressure and reducing conditions required for hydrate formation commonly occur at known disposal sites. In fact, a mixed TO hydrate is more stable than methane hydrate by almost 10°C. Here we show that in the presence of hydrate formation, as with other hydrate guest molecules, the TO solubility trend was reversed and solubility decreased in response to lower temperatures. The relatively low solubility in water coupled with the ability to form a hydrate within marine sediments can greatly decrease molecular mobility and increase chemical lifetime. Mixing will reduce concentrations of TO in the ocean water column below the detection limits established here. But the solubility data reveals the concentrations that will characterize marine pore waters at such sites, and these are readily detectable. Development of pore water Raman sensing techniques are underway.

Zhang, X.; Hester, K. C.; Walz, P. M.; Peltzer, E. T.; Brewer, P. G.

2008-12-01

221

Heterogeneous reaction rates in an ionic liquid: quantitative results from two-dimensional multiple population-period transient spectroscopy.  

PubMed

The hypotheses that ionic liquids are structurally heterogeneous at the molecular level and, even further, that this heterogeneity can transfer to the rates of reactions run in ionic liquids is being actively debated. Here, this hypothesis is tested using multiple population-period transient spectroscopy (MUPPETS), an emerging type of multidimensional measurement that resolves the kinetics of subensembles within a heterogeneous sample. A previous MUPPETS study of the excited-state twisting and electronic relaxation of auramine indicated that an ionic-liquid solvent induces rate dispersion due to a combination of heterogeneous and homogeneous processes, but those data could not quantitatively separate these contributions [Khurmi, C.; Berg, M. A. J. Phys. Chem. Lett.2010, 1, 161]. New MUPPETS data that include phase resolution and subtraction of thermal gratings are presented here and are successfully modeled. The total range of reaction rates (10--90%) is a factor of 70. If the solvent effect is viewed as a set of local viscosities, the viscosity distribution is broad and highly asymmetric. However, if the solvent is viewed as changing a reaction barrier, the data correspond to a Gaussian distribution of barrier heights. The relaxation of each subensemble is nonexponential with an initial induction period, but the shape of the decay is invariant across the rate distribution. A small (2%), long-lived component is identified as a part of the homogeneous kinetic scheme and thus as a secondary channel for excited-state relaxation, not as an impurity or alternative ground-state form of auramine. On the basis of these results, we suggest that the primary cause of rate heterogeneity is a long-lived local electric field acting on the charge redistribution during the reaction. PMID:21630702

Sahu, Kalyanasis; Kern, Sean J; Berg, Mark A

2011-07-14

222

Rapid and Quantitative Detection of the Microbial Spoilage of Meat by Fourier Transform Infrared Spectroscopy and Machine Learning  

PubMed Central

Fourier transform infrared (FT-IR) spectroscopy is a rapid, noninvasive technique with considerable potential for application in the food and related industries. We show here that this technique can be used directly on the surface of food to produce biochemically interpretable “fingerprints.” Spoilage in meat is the result of decomposition and the formation of metabolites caused by the growth and enzymatic activity of microorganisms. FT-IR was exploited to measure biochemical changes within the meat substrate, enhancing and accelerating the detection of microbial spoilage. Chicken breasts were purchased from a national retailer, comminuted for 10 s, and left to spoil at room temperature for 24 h. Every hour, FT-IR measurements were taken directly from the meat surface using attenuated total reflectance, and the total viable counts were obtained by classical plating methods. Quantitative interpretation of FT-IR spectra was possible using partial least-squares regression and allowed accurate estimates of bacterial loads to be calculated directly from the meat surface in 60 s. Genetic programming was used to derive rules showing that at levels of 107 bacteria·g?1 the main biochemical indicator of spoilage was the onset of proteolysis. Thus, using FT-IR we were able to acquire a metabolic snapshot and quantify, noninvasively, the microbial loads of food samples accurately and rapidly in 60 s, directly from the sample surface. We believe this approach will aid in the Hazard Analysis Critical Control Point process for the assessment of the microbiological safety of food at the production, processing, manufacturing, packaging, and storage levels. PMID:12039738

Ellis, David I.; Broadhurst, David; Kell, Douglas B.; Rowland, Jem J.; Goodacre, Royston

2002-01-01

223

Quantitative chemical derivatization technique in time-of-flight secondary ion mass spectrometry for surface amine groups on plasma-polymerized ethylenediamine film.  

PubMed

A chemical derivatization technique in time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been developed to quantify the surface density of amine groups of plasma-polymerized ethylenediamine thin film deposited on a glass surface by inductively coupled plasma chemical vapor deposition. Chemical tags of 4-nitrobenzaldehyde or pentafluorobenzaldehyde were hybridized with the surface amine groups and were detected in TOF-SIMS spectra as characteristic molecular secondary ions. The surface amine density was controlled in a reproducible manner as a function of deposition plasma power and was also quantified using UV-visible spectroscopy. A good linear correlation was observed between the results of TOF-SIMS and UV-visible measurements as a function of plasma power. This shows that the chemical derivatization technique in TOF-SIMS analysis would be useful in quantifying the surface density of specific functional groups that exist on the organic surface. PMID:15987119

Kim, Jinmo; Shon, Hyun Kyong; Jung, Donggeun; Moon, Dae Won; Han, Sang Yun; Lee, Tae Geol

2005-07-01

224

[Application of near infrared spectroscopy to qualitative identification and quantitative determination of Puccinia strii formis f. sp. tritici and P. recondita f. sp. tritici].  

PubMed

To realize qualitative identification and quantitative determination of Puccinia strii formis f. sp. tritici (Pst) and P. recondita f. sp. tritici (Prt), a qualitative identification model was built using near infrared reflectance spectroscopy (NIRS) combined with distinguished partial least squares (DPLS), and a quantitative determination model was built using NIRS combined with quantitative partial least squares (QPLS). In this study, 100 pure samples including 50 samples of Pst and 50 samples of Prt were obtained, and 120 mixed samples including three replicates of mixed urediospores of the two kinds of pathogen in different proportions (the content of Pst was within the range of 2. 5% 100% with 2. 5% as the gradient) were obtained. Then the spectra of the samples were collected using MPA spectrometer, respectively. Both pure samples and mixed samples were divided into training set and testing set with the ratio equal to 2:1. Qualitative identification model and quantitative determination model were built using internal cross-validation method in the spectral region 4,000--10,000 cm(-1) based on the training sets from pure samples and mixed samples, respectively. The results showed that the identification rates of the Pst-Prt qualitative identification model for training set and testing set were both up to 100. 00% when scatter correction was used as the preprocessing method of the spectra and the number of principal components was 3. When 'range normalization + scatter correction' was used as the preprocessing method of the spectra and the number of principal components was 6, determination coefficient (RZ), standard error of calibration (SEC) and average absolute relative deviation(AARD) of the Pst-Prt quantitative determination model for training set were 99.36%, 2.31% and 8.94%, respectively, and R2, standard error of prediction (SEP) and AARD for testing set were 99.37%, 2.29% and 5. 0%, respectively. The results indicated that qualitative identification and quantitative determination of Pst and Prt using near infrared spectroscopy technology are feasible and that the Pst-Prt qualitative identification model and the Pst-Prt quantitative determination model built in this study were reliable and stable. A new method based on NIRS was provided for qualitative identification and quantitative determination of plant pathogen in this study. PMID:25208382

Li, Xiao-Long; Ma, Zhan-Hong; Zhao, Long-Lian; Li, Jun-Hui; Wang, Hai-Guang

2014-03-01

225

Qualitative and simultaneous quantitative analysis of cimetidine polymorphs by ultraviolet-visible and shortwave near-infrared diffuse reflectance spectroscopy and multivariate calibration models.  

PubMed

The object of the present study was to investigate the feasibility of applying ultraviolet-visible and shortwave near-infrared diffuse reflectance spectroscopy (UV-vis-SWNIR DRS) coupled with chemometrics in qualitative and simultaneous quantitative analysis of drug polymorphs, using cimetidine as a model drug. Three polymorphic forms (A, B and D) and a mixed crystal (M1) of cimetidine, obtained by preparation under different crystallization conditions, were characterized by microscopy, X-ray powder diffraction (XRPD) and infrared spectroscopy (IR). The discriminant models of four forms (A, B, D and M1) were established by discriminant partial least squares (PLS-DA) using different pretreated spectra. The R and RMSEP of samples in the prediction set by discriminant model with original spectra were 0.9959 and 0.1004. Among the quantitative models of binary mixtures (A and D) established by partial least squares (PLS) and least squares-support vector machine (LS-SVM) with different pretreated spectra, the LS-SVM models based on original and MSC spectra had better prediction effect with a R of 1.0000 and a RMSEP of 0.0134 for form A, and a R of 1.0000 and a RMSEP of 0.0024 for form D. For ternary mixtures, the established PLS quantitative models based on normalized spectra had relatively better prediction effect for forms A, B and D with R of 0.9901, 0.9820 and 0.9794 and RMSEP of 0.0471, 0.0529 and 0.0594, respectively. This research indicated that UV-vis-SWNIR DRS can be used as a simple, rapid, nondestructive qualitative and quantitative method for the analysis of drug polymorphs. PMID:25497893

Feng, Yuyan; Li, Xiangling; Xu, Kailin; Zou, Huayu; Li, Hui; Liang, Bing

2015-02-01

226

FT-IR TRANSMISSION SPECTROSCOPY FOR QUANTITATION OF AMMONIUM BISULFATE IN FINE PARTICULATE MATTER COLLECTED ON TEFLON FILTERS  

EPA Science Inventory

A quantitative measurement method for fine particle bisulfatein ammonium bisulfate collected from the ambient air onto Teflon filters is described. nfrared absorbance measurements of the Teflon filters are made before and after particle collection. ubtraction of the two spectra r...

227

Ordered silicon nanocones arrays for label-free DNA quantitative analysis by surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Ordered vertical silicon nanocones arrays coated with silver nanoparticles (AgNPs@SiNCs) are developed as surface-enhanced Raman scattering (SERS)-active substrate, which features good uniformity and reliable reproducibility of SERS signals. Label-free DNA at low concentrations (10-8 M) could be quantitatively analyzed via SERS using the AgNPs@SiNCs. The Raman peak at 732 cm-1 due to adenine breathing mode was selected as an endogenous Raman marker for quantitative detection of label-free DNA. The AgNPs@SiNCs as high-performance SERS-active substrates are attractive for surface enhancement mechanism investigation and biochemical sensing applications.

Xu, Ting-Ting; Huang, Jian-An; He, Li-Fang; He, Yao; Su, Shao; Lee, Shuit-Tong

2011-10-01

228

Homogeneity testing and quantitative analysis of manganese (Mn) in vitrified Mn-doped glasses by laser-induced breakdown spectroscopy (LIBS)  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS), an atomic emission spectroscopy method, has rapidly grown as one of the best elemental analysis techniques over the past two decades. Homogeneity testing and quantitative analysis of manganese (Mn) in manganese-doped glasses have been carried out using an optimized LIBS system employing a nanosecond ultraviolet Nd:YAG laser as the source of excitation. The glass samples have been prepared using conventional vitrification methods. The laser pulse irradiance on the surface of the glass samples placed in air at atmospheric pressure was about 1.7×109 W/cm2. The spatially integrated plasma emission was collected and imaged on to the spectrograph slit using an optical-fiber-based collection system. Homogeneity was checked by recording LIBS spectra from different sites on the sample surface and analyzing the elemental emission intensities for concentration determination. Validation of the observed LIBS results was done by comparison with scanning electron microscope- energy dispersive X-ray spectroscopy (SEM-EDX) surface elemental mapping. The analytical performance of the LIBS system has been evaluated through the correlation of the LIBS determined concentrations of Mn with its certified values. The results are found to be in very good agreement with the certified concentrations.

Unnikrishnan, V. K.; Nayak, Rajesh; Kartha, V. B.; Santhosh, C.; Sonavane, M. S.; Yeotikar, R. G.; Shah, M. L.; Gupta, G. P.; Suri, B. M.

2014-09-01

229

Near infrared spectroscopy in combination with chemometrics as a process analytical technology (PAT) tool for on-line quantitative monitoring of alcohol precipitation.  

PubMed

The application of near infrared (NIR) spectroscopy for on-line quantitative monitoring of alcohol precipitation of the Danhong injection was investigated. For the NIR measurements, two fiber optic probes designed to transmit NIR radiation through a 2mm path length flow cell were applied to collect spectra in real-time. Particle swarm optimization- (PSO-) based least square support vector machines (LS-SVM) and partial least squares (PLS) models were developed for quantitative analysis of the critical intermediate quality attributes: the soluble solid content (SSC) and concentrations of danshensu (DSS), protocatechuic aldehyde (PA), hydroxysafflor yellow A (HSYA) and salvianolic acid B (SAB). The optimal models were then used for on-line quantitative monitoring of alcohol precipitation. The results showed that the PSO-based LS-SVM with a radial basis function (RBF) kernel was slightly better than the conventional PLS method, even though both methods exhibited satisfactory fitting results and predictive abilities. In this study, successful models were built and applied on-line; these models proffer real-time data and instant feedback about alcohol precipitation. PMID:23357639

Jin, Ye; Wu, Zengzeng; Liu, Xuesong; Wu, Yongjiang

2013-04-15

230

Salicylate Detection by Complexation with Iron(III) and Optical Absorbance Spectroscopy: An Undergraduate Quantitative Analysis Experiment  

ERIC Educational Resources Information Center

An experiment for the undergraduate quantitative analysis laboratory involving applications of visible spectrophotometry is described. Salicylate, a component found in several medications, as well as the active by-product of aspirin decomposition, is quantified. The addition of excess iron(III) to a solution of salicylate generates a deeply…

Mitchell-Koch, Jeremy T.; Reid, Kendra R.; Meyerhoff, Mark E.

2008-01-01

231

Quantitative Analysis of Simulated Illicit Street-Drug Samples Using Raman Spectroscopy and Partial Least Squares Regression  

Microsoft Academic Search

Modern drug laws require that a seized sample be characterized for both the illegal substances present and the quantity of each of those substances. The goal of this work was to develop a common approach to model development based on Raman spectroscopic analysis followed by partial least squares (PLS) regression that would allow us to obtain quantitative information from simulated

Owen S. Fenton; Lindsey A. Tonge; Taylor H. Moot; Kimberley A. Frederick

2011-01-01

232

Rapid quantitative assessment of the adulteration of virgin olive oils with hazelnut oils using Raman spectroscopy and chemometrics.  

PubMed

The authentication of extra virgin olive oil and its adulteration with lower-priced oils are serious problems in the olive oil industry. In addition to the obvious effect on producer profits, adulteration can also cause severe health and safety problems. A number of techniques, including chromatographic and spectroscopic methods, have recently been employed to assess the purity of olive oils. In this study Raman spectroscopy together with multivariate and evolutionary computational-based methods have been employed to assess the ability of Raman spectroscopy to discriminate between chemically very closely related oils. Additionally, the levels of hazelnut oils used to adulterate extra virgin olive oil were successfully quantified using partial least squares and genetic programming. PMID:14518936

López-Díez, E Consuelo; Bianchi, Giorgio; Goodacre, Royston

2003-10-01

233

Identification and Quantitation of Phosphorus Metabolites in Yeast Neutral pH Extracts by Nuclear Magnetic Resonance Spectroscopy  

Microsoft Academic Search

31P NMR spectroscopy offers a possibility to obtain a survey of all low-molecular-weight phosphorylated compounds in yeast. The yeast cells have been extracted using chloroform into a neutral aqueous phase. The use of high fields and the neutral pH extracts, which are suitable for NMR analysis, results in well-resolved 31P NMR spectra. Two-dimensional NMR experiments, such as proton-detected heteronuclear single

Anita Teleman; Peter Richard; Mervi Toivari; Merja Penttilä

1999-01-01

234

High-Resolution NMR Spectroscopy: An Alternative Fast Tool for Qualitative and Quantitative Analysis of Diacylglycerol (DAG) Oil  

Microsoft Academic Search

Multinuclear (1H, 13C, 31P) and multidimensional NMR spectroscopy was employed for the analysis of diacylglycerol (DAG) oil and the quantification\\u000a of its acylglycerols and acyl chains composition. A number of gradient selected two dimensional NMR techniques (TOCSY, HSQC-DEPT,\\u000a HSQC-TOCSY, and HMBC) facilitated the assignment of the complex one dimensional 1H- and 13C-NMR spectra. In several cases, the aforementioned 2D-NMR techniques

Emmanuel Hatzakis; Alexia Agiomyrgianaki; Sarantos Kostidis; Photis Dais

235

Using wide-field quantitative diffuse reflectance spectroscopy in combination with high-resolution imaging for margin assessment  

NASA Astrophysics Data System (ADS)

Due to the large number of women diagnosed with breast cancer and the lack of intra-operative tools, breast cancer margin assessment presents a significant unmet clinical need. Diffuse reflectance spectral imaging provides a method for quantitatively interrogating margins of lumpectomy specimens. We have previously found that [?- carotene]/?s' is a diagnostically important parameter but both parameters, [?-carotene] and ?s', were derived from a low resolution parameter map and are subject to the tissue type and heterogeneity present in the breast. In this study, we used diffuse reflectance measurements from individual sites co-registered with high resolution microendoscopy (HRME) images to determine if the combined performance of these technologies could improve margin assessment. By comparing the optical parameters of [?-carotene] and ?s' to the quantitative HRME image endpoints of feature size, feature density and normalized fluorescence, we determined that adding HRME to spectral imaging can improve the specificity of our diffuse reflectance spectral imaging system.

Kennedy, Stephanie; Mueller, Jenna; Bydlon, Torre; Brown, J. Quincy; Ramanujam, Nimmi

2011-03-01

236

Raman spectroscopy provides a rapid, non-invasive method for quantitation of starch in live, unicellular microalgae.  

PubMed

Conventional methods for quantitation of starch content in cells generally involve starch extraction steps and are usually labor intensive, thus a rapid and non-invasive method will be valuable. Using the starch-producing unicellular microalga Chlamydomonas reinhardtii as a model, we employed a customized Raman spectrometer to capture the Raman spectra of individual single cells under distinct culture conditions and along various growth stages. The results revealed a nearly linear correlation (R(2) = 0.9893) between the signal intensity at 478 cm(-1) and the starch content of the cells. We validated the specific correlation by showing that the starch-associated Raman peaks were eliminated in a mutant strain where the AGPase (ADP-glucose pyrophosphorylase) gene was disrupted and consequentially the biosynthesis of starch blocked. Furthermore, the method was validated in an industrial algal strain of Chlorella pyrenoidosa. This is the first demonstration of starch quantitation in individual live cells. Compared to existing cellular starch quantitation methods, this single-cell Raman spectra-based approach is rapid, label-free, non-invasive, culture-independent, low-cost, and potentially able to simultaneously track multiple metabolites in individual live cells, therefore should enable many new applications. PMID:24906189

Ji, Yuetong; He, Yuehui; Cui, Yanbin; Wang, Tingting; Wang, Yun; Li, Yuanguang; Huang, Wei E; Xu, Jian

2014-12-01

237

Estimation of soil clay and organic matter using two quantitative methods (PLSR and MARS) based on reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

A rapid and inexpensive soil analytical technique is needed for soil quality assessment and accurate mapping. This study investigated a method for improved estimation of soil clay (SC) and organic matter (OM) using reflectance spectroscopy. Seventy soil samples were collected from Sinai peninsula in Egypt to estimate the soil clay and organic matter relative to the soil spectra. Soil samples were scanned with an Analytical Spectral Devices (ASD) spectrometer (350-2500 nm). Three spectral formats were used in the calibration models derived from the spectra and the soil properties: (1) original reflectance spectra (OR), (2) first-derivative spectra smoothened using the Savitzky-Golay technique (FD-SG) and (3) continuum-removed reflectance (CR). Partial least-squares regression (PLSR) models using the CR of the 400-2500 nm spectral region resulted in R2 = 0.76 and 0.57, and RPD = 2.1 and 1.5 for estimating SC and OM, respectively, indicating better performance than that obtained using OR and SG. The multivariate adaptive regression splines (MARS) calibration model with the CR spectra resulted in an improved performance (R2 = 0.89 and 0.83, RPD = 3.1 and 2.4) for estimating SC and OM, respectively. The results show that the MARS models have a great potential for estimating SC and OM compared with PLSR models. The results obtained in this study have potential value in the field of soil spectroscopy because they can be applied directly to the mapping of soil properties using remote sensing imagery in arid environment conditions. Key Words: soil clay, organic matter, PLSR, MARS, reflectance spectroscopy.

Nawar, Said; Buddenbaum, Henning; Hill, Joachim

2014-05-01

238

ERDA Paper: Quantitative Measurement of Chromium, Manganese, Rhenium, and Magnesium in Liquid by Laser-Induced Breakdown Spectroscopy  

SciTech Connect

A technique is needed to measure Tc during the waste process at DOE Hanford site. Laser induced breakdown spectroscopy (LIBS), a laser-based, non-intrusive, and sensitive optical diagnostic technique for measuring the concentration of various atomic and molecular species in test media, has the potential to be an on-line monitor to monitor Tc in the effluent from the Tc removal column to track the technetium removal process. In this work, we evaluate the analytical figure of merit of LIBS system for the element that has similar properties to Tc.

Keller, E.L.

2000-06-27

239

Quantitative analysis of melamine by multi-way partial least squares model with two-dimensional near-infrared correlation spectroscopy  

NASA Astrophysics Data System (ADS)

A new approach for quantitative analysis of melamine in milk was proposed based on two-dimensional (2D) correlation near-infrared spectroscopy and multi-way partial least squares (N-PLS) in this paper. 40 pure milk samples and 40 milk samples adulterated with different contents of melamine were prepared. The near-infrared transmittance spectra of all samples were measured at room temperature. Then 2D NIR-NIR correlation spectroscopy under the perturbation of adulterant concentration was calculated and N-PLS model for the melamine concentration was established with 2D correlation spectra (28x51x51). For the prediction set, the root mean square errors of prediction (RMSEP) for melamine concentration was 0.067 g/L and the coefficient correlation between actual reference values and predicted values was 0.999, which means the model has good predictive ability. For comparison purpose, partial least squares (PLS) model was also built using the conventional one-dimensional near-infrared spectra (28x51), where the RMSEP and the coefficient correlation were 0.079 g/L and 0.998, respectively. The average relative prediction error was 22.9% for N-PLS model; whereas it was 122.4% for PLS model. The N-PLS models yielded relatively low RMSEP and average relative prediction error as compared to PLS model. Therefore, N-PLS method was more robust than PLS method for accurate quantification of the concentration of melamine in milk.

Yang, Renjie; Liu, Rong; Xu, Kexin; Yang, Yanrong

2014-03-01

240

Quantitative compositional profiling of conjugated quantum dots with single atomic layer depth resolution via time-of-flight medium-energy ion scattering spectroscopy.  

PubMed

We report the quantitative compositional profiling of 3-5 nm CdSe/ZnS quantum dots (QDs) conjugated with a perfluorooctanethiol (PFOT) layer using the newly developed time-of-flight (TOF) medium-energy ion scattering (MEIS) spectroscopy with single atomic layer resolution. The collection efficiency of TOF-MEIS is 3 orders of magnitude higher than that of conventional MEIS, enabling the analysis of nanostructured materials with minimized ion beam damage and without ion neutralization problems. The spectra were analyzed using PowerMEIS ion scattering simulation software to allow a wide acceptance angle. Thus, the composition and core-shell structure of the CdSe cores and ZnS shells were determined with a 3% composition uncertainty and a 0.2-nm depth resolution. The number of conjugated PFOT molecules per QD was also quantified. The size and composition of the QDs were consistent with those obtained from high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy, respectively. We suggest TOF-MEIS as a nanoanalysis technique to successfully elucidate the core-shell and conjugated layer structures of QDs, which is critical for the practical application of QDs in various nano- and biotechnologies. PMID:24350771

Jung, Kang-Won; Yu, Hyunung; Min, Won Ja; Yu, Kyu-Sang; Sortica, M A; Grande, Pedro L; Moon, DaeWon

2014-01-21

241

Principles, performance, and applications of spectral reconstitution (SR) in quantitative analysis of oils by Fourier transform infrared spectroscopy (FT-IR).  

PubMed

Spectral reconstitution (SR) is a dilution technique developed to facilitate the rapid, automated, and quantitative analysis of viscous oil samples by Fourier transform infrared spectroscopy (FT-IR). This technique involves determining the dilution factor through measurement of an absorption band of a suitable spectral marker added to the diluent, and then spectrally removing the diluent from the sample and multiplying the resulting spectrum to compensate for the effect of dilution on the band intensities. The facsimile spectrum of the neat oil thus obtained can then be qualitatively or quantitatively analyzed for the parameter(s) of interest. The quantitative performance of the SR technique was examined with two transition-metal carbonyl complexes as spectral markers, chromium hexacarbonyl and methylcyclopentadienyl manganese tricarbonyl. The estimation of the volume fraction (VF) of the diluent in a model system, consisting of canola oil diluted to various extents with odorless mineral spirits, served as the basis for assessment of these markers. The relationship between the VF estimates and the true volume fraction (VF(t)) was found to be strongly dependent on the dilution ratio and also depended, to a lesser extent, on the spectral resolution. These dependences are attributable to the effect of changes in matrix polarity on the bandwidth of the ?(CO) marker bands. Excellent VF(t) estimates were obtained by making a polarity correction devised with a variance-spectrum-delineated correction equation. In the absence of such a correction, SR was shown to introduce only a minor and constant bias, provided that polarity differences among all the diluted samples analyzed were minimal. This bias can be built into the calibration of a quantitative FT-IR analytical method by subjecting appropriate calibration standards to the same SR procedure as the samples to be analyzed. The primary purpose of the SR technique is to simplify preparation of diluted samples such that only approximate proportions need to be adhered to, rather than using exact weights or volumes, the marker accounting for minor variations. Additional applications discussed include the use of the SR technique in extraction-based, quantitative, automated FT-IR methods for the determination of moisture, acid number, and base number in lubricating oils, as well as of moisture content in edible oils. PMID:23601545

García-González, Diego L; Sedman, Jacqueline; van de Voort, Frederik R

2013-04-01

242

Quantitative Analysis of Adulterations in Oat Flour by FT-NIR Spectroscopy, Incomplete Unbalanced Randomized Block Design, and Partial Least Squares  

PubMed Central

This paper developed a rapid and nondestructive method for quantitative analysis of a cheaper adulterant (wheat flour) in oat flour by NIR spectroscopy and chemometrics. Reflectance FT-NIR spectra in the range of 4000 to 12000?cm?1 of 300 oat flour objects adulterated with wheat flour were measured. The doping levels of wheat flour ranged from 5% to 50% (w/w). To ensure the generalization performance of the method, both the oat and the wheat flour samples were collected from different producing areas and an incomplete unbalanced randomized block (IURB) design was performed to include the significant variations that may be encountered in future samples. Partial least squares regression (PLSR) was used to develop calibration models for predicting the levels of wheat flour. Different preprocessing methods including smoothing, taking second-order derivative (D2), and standard normal variate (SNV) transformation were investigated to improve the model accuracy of PLS. The root mean squared error of Monte Carlo cross-validation (RMSEMCCV) and root mean squared error of prediction (RMSEP) were 1.921 and 1.975 (%, w/w) by D2-PLS, respectively. The results indicate that NIR and chemometrics can provide a rapid method for quantitative analysis of wheat flour in oat flour. PMID:25143857

Wang, Ning; Zhang, Xingxiang; Yu, Zhuo; Li, Guodong; Zhou, Bin

2014-01-01

243

Identification and Quantitation of Phenylalanine in the Brain of Patients with Phenylketonuria by Means of Localized in Vivo1H Magnetic-Resonance Spectroscopy  

NASA Astrophysics Data System (ADS)

Localized proton MR spectroscopy was used to identify phenylalanine (PHE) and to quantitate its cerebral concentration in patients with type I phenylketonuria (PKU). Data acquisition was optimized for the detection of low-concentration metabolites, using a short TE (20 ms) double Hahn-echo localization sequence for large volumes within the head coil and for smaller volumes using a surface coil, Previously described methods to quantitate localized MR spectra were extended to cover the case of low-concentration metabolites, unevenly distributed in three brain compartments and measured in difference spectra only. PHE content was determined in difference spectra of four PKU patients with respect to normals and in one patient before and after an oral load of L-PHE, PHE concentrations of 0.3 to 0.6 mmol/kg brain tissue were obtained, resulting in a concentration gradient for PHE between blood and brain tissue of 2.4 to 3.0, No significant changes were found for the abundant metabolites in gray or white matter. Previously reported MRI changes were confirmed to be due to increased cerebro-spinal-fluid-like spaces.

Kreis, R.; Pietz, J.; Penzien, J.; Herschkowitz, N.; Boesch, C.

244

Quantitative analysis of CN/TiCN/TiN multilayers and their thermal stability by Auger electron spectroscopy and Rutherford backscattering spectrometry depth profiles  

SciTech Connect

CN/TiCN/TiN multilayers and the respective single layers have been deposited on Si(100) substrates using a dual ion-beam sputtering system. Both the multilayers and the respective single layers have been chemically characterized by Auger electron spectroscopy (AES) depth profiling combined with factor analysis and by Rutherford backscattering spectrometry (RBS). The combination of AES and RBS allows a quantitative chemical characterization of the multilayer and the respective single layers. Whereas RBS has some difficulties to determine the in-depth distribution of the light elements along the multilayer, AES depth profiling enables their quantitative analysis and even their chemical state along the multilayer. On the contrary, RBS shows its advantages to determine the heavy elements, including the contaminants incorporated during the deposition process (e.g., W). Under special experimental conditions it is shown that RBS is able to determine the composition of the single layers (i.e., CN/Si, TiCN/Si, and TiN/Si) in good agreement with AES depth profiling. As a result of this complementary use we obtain a complete quantitative chemical characterization of the single layers and multilayers. In addition, the thermal stability of the multilayers upon heating for 1 h in vacuum and ambient atmospheres at 500 deg. C has been studied by AES depth profiling. The results show that whereas the multilayer is stable in vacuum it undergoes significant changes when it is heated in air. In fact, it is shown that annealing in air for 1 h causes the disappearance of the CN top layer and the oxidation of the TiCN layer that leads to the formation of TiO{sub 2} on its surface.

Prieto, P.; Morant, C.; Climent-Font, A.; Munoz, A.; Elizalde, E.; Sanz, J.M. [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid, Spain and Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)

2006-03-15

245

Quantitative analysis of sodium carbonate and sodium bicarbonate in solid mixtures using Fourier transform infrared spectroscopy (FT-IR).  

PubMed

An analytical methodology is proposed based on constant ratio and absorbance correction methods to quantify sodium carbonate, Na?CO? (1450 cm?¹), and sodium bicarbonate, NaHCO? (1000 cm?¹, 1923 cm?¹), in solid mixtures using Fourier transform infrared (FT-IR) spectroscopy. Potassium ferricyanide, K?Fe(CN)? (2117cm?¹), was used as an internal standard to get characteristic parameters. NaHCO? was quantified using the constant ratio method. Spectral interference of NaHCO? in Na?CO? (1450 cm?¹) was corrected using the absorbance correction method. The corrected absorbance was successfully applied to quantify Na?CO? (1450 cm?¹) in the mixture using the constant ratio method. The results obtained for simulated samples were satisfactory (relative standard deviation less than 7%) for all samples. PMID:23876722

Joshi, Shailesh; Kalyanasundaram, Sivasubramanian; Balasubramanian, Venkatraman

2013-08-01

246

A quantitative study of the intracellular dynamics of fluorescently labelled glyco-gold nanoparticles via fluorescence correlation spectroscopy.  

PubMed

The dynamic behaviour of gold nanoparticles functionalised with glucose (Glc-Au NPs) has been studied here by means of fluorescence correlation spectroscopy (FCS). Meaningful data on the state of aggregation and dynamics of Glc-Au NPs fluorescently-labelled with HiLyte Fluor647 (Glc-Au-Hi NPs) in the intracellular environment were obtained. Moreover, the work presented here shows that FCS can be used to visualise the presence of single NPs or NP aggregates following uptake and to estimate, locally, NP concentrations within the cell. FCS measurements become possible after applying a "prebleaching" methodology, when the immobile NP fraction has been effectively removed and thus significant FCS data has been recorded. In this study, Glc-Au-Hi NPs have been incubated with HepG2 cells and their diffusion time in the intracellular environment has been measured and compared with their diffusion value in water and cell media. PMID:24639360

Murray, Richard A; Qiu, Yuan; Chiodo, Fabrizio; Marradi, Marco; Penadés, Soledad; Moya, Sergio E

2014-07-01

247

Atomic emission stratigraphy by laser-induced plasma spectroscopy: Quantitative depth profiling of metal thin film systems  

NASA Astrophysics Data System (ADS)

Laser-induced plasma spectroscopy (LIPS) with a frequency-quadrupled Nd:YAG laser (266 nm, pulse duration: 4 ns) was applied to a metallic layer system consisting of an electrodeposited copper layer (30 ?m) on an aluminium substrate. A stratigraphic model describing the emission signal in dependence of the pulse number was developed, which can explain several effects originating from laser ablation of various thin top layers by means of the Gaussian beam cross section character. This model was applied to trace elements through layers with thicknesses that are in the range of the resolvable depth, given by the single-pulse ablation rate, by means of empirical fitting functions. Additionally, the contribution of redeposited bulk material to the characteristic shape of emission-traces when averaging spot arrays with varying spacing could be quantified. This can be used to estimate cross-contamination in analytical applications where ablations need to be performed at close spacing.

Nagy, Tristan O.; Pacher, Ulrich; Pöhl, Hannes; Kautek, Wolfgang

2014-05-01

248

Adsorption and coadsorption on Ni(100): Quantitative applications of auger electron spectroscopy to the elements C, P, Pb, Sn  

NASA Astrophysics Data System (ADS)

Quantitative AES has been applied to simple adsorbates on Ni(100). Methods previously developed for calibration, involving coadsorption of a "contaminant" with an adsorbed metal vapour, are difficult to apply because of the tendency of the metal to adsorb on top of the contaminant in the case of carbon and to cause desorption in the case of phosphorus. A calibration for carbon can be made, however, by means of a simple analysis. A calibration for phosphorus is based on interpretations of the LEED patterns near a "saturation" coverage where evidence is found for compact monolayer arrangements. The segregation of phosphorus from the bulk was not reversible in the temperature range studied (500-700°C).

Oda, Osamu; Rhead, Gordon E.

1980-02-01

249

Gold nanorods as surface enhanced Raman spectroscopy substrates for sensitive and selective detection of ultra-low levels of dithiocarbamate pesticides.  

PubMed

We report the use of gold nanorods as solution-based SERS substrates for the detection of ultralow-levels of three different dithiocarbamate fungicides: thiram, ferbam and ziram. Gold nanorods are attractive to use as SERS substrates due to the ability to tune the surface plasmon resonance of the nanoparticles to the laser excitation wavelength of the Raman spectrometer equipped with a 785 nm diode laser. The gold nanorods are synthesized using a seed-mediated growth method and characterized using UV-Visible spectroscopy, zeta potential, and TEM. The gold nanorods have an aspect ratio of 2.19 ± 0.21 and have an average length of 37.81 ± 4.83 nm. SERS spectra are acquired at different concentrations of each fungicide and calibration curves are obtained by monitoring the intensity of the band arising from the ?(C-N) stretching mode coupled to the symmetric ?(CH(3)) motion. The limits of detection and limits of quantitation are obtained for each fungicide. The limits of detection are 11.00 ± 0.95 nM, 8.00 ± 1.01 nM, and 4.20 ± 1.22 nM for thiram, ferbam, and ziram respectively. The limits of quantitation are 34.43 ± 0.95 nM, 25.61 ± 1.01 nM, and 12.94 ± 1.22 nM for thiram, ferbam, and ziram respectively. It can be seen that the three different dithiocarbamates can be detected in the low nM range based on the limits of detection that are achieved. PMID:22977883

Saute, Benjamin; Premasiri, Ranjith; Ziegler, Lawrence; Narayanan, Radha

2012-11-01

250

Quantitative elemental localisation in leaves and stems of nickel hyperaccumulating shrub Hybanthusfloribundus subsp. floribundus using micro-PIXE spectroscopy  

NASA Astrophysics Data System (ADS)

Hybanthusfloribundus (Lindl.) F.Muell. subsp. floribundus is a native Australian nickel (Ni) hyperaccumulating shrub and a promising species for rehabilitation and phytoremediation of Ni tailings. Spatial localisation and quantification of Ni in leaf and stem tissues of H.floribundus subsp. floribundus was studied using micro-proton-induced X-ray emission (micro-PIXE) spectroscopy. Young plants, grown in a potting mix under controlled glasshouse conditions were exposed to Ni concentrations of 0 and 26 mM kg -1 for 20 weeks. Leaf and stem samples were hand-sectioned and freeze-dried prior to micro-PIXE analysis. Elemental distribution maps of leaves revealed Ni concentration of 7800 mg kg -1 dry weight (DW) in whole leaf sections, which was identical to the bulk tissue analysis. Elemental maps showed that Ni was preferentially localised in the adaxial epidermis (10,000 mg kg -1 DW) and reached a maximum of up to 10,000 mg kg -1 DW in the leaf margin. Freeze-dried stem sections from the same plants contained lower Ni than leaf tissues (1800 mg kg -1 versus 7800 mg kg -1 DW, respectively), however did not resolve a clear pattern of compartmentalisation across different anatomical regions. Our results suggest localisation in epidermal cells is an important physiological mechanism involved in Ni accumulation and tolerance in leaves of H.floribundus subsp. floribundus.

Kachenko, Anthony G.; Singh, Balwant; Bhatia, Naveen P.; Siegele, Rainer

2008-02-01

251

Quantitative Proton MR Spectroscopy as a Biomarker of Tumor Necrosis in the Rabbit VX2 Liver Tumor  

PubMed Central

Purpose To compare metabolic magnetic resonance (MR) imaging findings (ie, quantification of tumor choline concentration) with percentage of necrosis on pathologic examination in rabbits bearing VX2 liver tumors. Materials and Methods VX2 tumors were implanted in the livers of 16 rabbits. MR imaging was performed with a 1.5-T MR scanner and extremity coil, and a hydrogen-1 (1H) proton MR spectroscopy (1H MRS) imaging protocol was used. Rabbits were euthanized immediately after imaging, and the tumor was harvested and sliced at 4-mm intervals in the axial plane. Choline concentration was calculated and was compared with the percentage of tumor necrosis on pathologic examination. Results Mean tumor size at pathologic examination was 16 mm (range, 12-22 mm). Mean percentage of necrosis at pathologic examination was 22% (range, 4%-44%). Choline concentration showed a relatively high inverse correlation with percentage of necrosis on pathologic examination, with an r value of 0.78 (P < .002). Conclusions Choline concentration showed a relatively high inverse correlation with tumor necrosis on pathologic examination. Therefore, 1H MRS may be useful to assess tumor necrosis. PMID:21620723

Buijs, Manon; Vossen, Josephina A.; Geschwind, Jean-Francois H.; Salibi, Nouha; Pan, Li; Ventura, Veronica Prieto; Liapi, Eleni; Lee, Kwang Hun; Kamel, Ihab R.

2015-01-01

252

2D IR Spectroscopy using Four-Wave Mixing, Pulse Shaping, and IR Upconversion: A Quantitative Comparison  

PubMed Central

Recent technological advances have led to major changes in the apparatuses used to collect 2D IR spectra. Pulse shaping offers several advantages including rapid data collection, inherent phase stability, and phase cycling capabilities. Visible array detection via upconversion allows the use of visible detectors that are cheaper, faster, more sensitive, and less noisy than IR detectors. However, despite these advantages, many researchers are reluctant to implement these technologies. Here we present a quantitative study of the S/N of 2D IR spectra collected with a traditional four-wave mixing (FWM) apparatus, with a pulse shaping apparatus, and with visible detection via upconversion to address the question of whether or not weak chromophores at low concentrations are still accessible with such an apparatus. We find that the enhanced averaging capability of the pulse shaping apparatus enables the detection of small signals that would be challenging to measure even with the traditional FWM apparatus, and we demonstrate this ability on a sample of cyanylated dihydrofolate reductase (DHFR). PMID:23687988

Rock, William; Li, Yun-Liang; Pagano, Philip; Cheatum, Christopher M.

2013-01-01

253

Quantitative evaluation on activated property-tunable bulk liquid water with reduced hydrogen bonds using deconvoluted Raman spectroscopy.  

PubMed

Interesting properties of water with distinguishable hydrogen-bonding structure on interfacial phase or in confined environment have drawn wide attentions. However, these unique properties of water are only found within the interfacial phase and confined environment, thus, their applications are limited. In addition, quantitative evaluation on these unique properties associating with the enhancement of water's physical and chemical activities represents a notable challenge. Here we report a practicable production of free-standing liquid water at room temperature with weak hydrogen-bonded structure naming Au nanoparticles (NPs)-treated (AuNT) water via treating by plasmon-induced hot electron transfer occurred on resonantly illuminated gold NPs (AuNPs). Compared to well-known untreated bulk water (deionized water), the prepared AuNT water exhibits many distinct activities in generally physical and chemical reactions, such as high solubilities to NaCl and O2. Also, reducing interaction energy within water molecules provides lower overpotential and higher efficiency in electrolytic hydrogen production. In addition, these enhanced catalytic activities of AuNT water are tunable by mixing with deionized water. Also, most of these tunable activities are linearly proportional to its degree of nonhydrogen-bonded structure (DNHBS), which is derived from the O-H stretching in deconvoluted Raman spectrum. PMID:25471522

Chen, Hsiao-Chien; Mai, Fu-Der; Yang, Kuang-Hsuan; Chen, Liang-Yih; Yang, Chih-Ping; Liu, Yu-Chuan

2015-01-01

254

Application of quantitative (19) F nuclear magnetic resonance spectroscopy in tape-stripping experiments with natural microemulsions.  

PubMed

The skin penetration of flufenamic acid (Fluf) and fluconazole (Fluc) from innovative natural microemulsions was investigated in tape-stripping experiments on pig ears. The formulations were based on the eudermic surfactants lecithin, sucrose laurate, alkylpolyglycoside or a mixture thereof. The quantification of the penetrated drug amounts was executed by (19) F nuclear magnetic resonance (NMR) in comparison with high-performance liquid chromatography (HPLC). The data obtained by the (19) F NMR method were confirmed by additional quantitative studies using HPLC. An excellent linear correlation was found for Fluf as well as for Fluc between (19) F NMR and HPLC data. This work presents a strategy outlining the use of (19) F NMR to selectively monitor the skin penetration routes of fluorinated compounds. Fluc penetrated generally well into the stratum corneum with the significantly highest amounts from the sucrose laurate microemulsion on the tape strips 1-5. Similarly, the highest amounts of penetrated Fluf could be observed from the formulation based on sucrose laurate. In addition, NMR self-diffusion studies were conducted and revealed a bicontinuous microstructure of the investigated microemulsions. The skin penetration results are in good agreement with the obtained (19) F NMR self-diffusion coefficients of the active compounds in the microemulsion systems. PMID:23794482

Schwarz, Julia C; Hoppel, Magdalena; Kählig, Hanspeter; Valenta, Claudia

2013-08-01

255

Quantitative X-ray photoelectron spectroscopy-based depth profiling of bioleached arsenopyrite surface by Acidithiobacillus ferrooxidans  

NASA Astrophysics Data System (ADS)

In supergene environments, microbial activities significantly enhance sulfide oxidation and result in the release of heavy metals, causing serious contamination of soils and waters. As the most commonly encountered arsenic mineral in nature, arsenopyrite (FeAsS) accounts for arsenic contaminants in various environments. In order to investigate the geochemical behavior of arsenic during microbial oxidation of arsenopyrite, (2 3 0) surfaces of arsenopyrite slices were characterized after acidic (pH 2.00) and oxidative decomposition with or without an acidophilic microorganism Acidithiobacillus ferrooxidans. The morphology as well as chemical and elemental depth profiles of the oxidized arsenopyrite surface were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. With the mediation of bacteria, cell-shaped and acicular pits were observed on the reacted arsenopyrite surface, and the concentration of released arsenic species in solution was 50 times as high as that of the abiotic reaction after 10 days reaction. Fine-scale XPS depth profiles of the reacted arsenopyrite surfaces after both microbial and abiotic oxidation provided insights into the changes in chemical states of the elements in arsenopyrite surface layers. Within the 450 nm surface layer of abiotically oxidized arsenopyrite, Fe(III)-oxides appeared and gradually increased towards the surface, and detectable sulfite and monovalent arsenic appeared above 50 nm. In comparison, higher contents of ferric sulfate, sulfite, and arsenite were found in the surface layer of approximately 3 ?m of the microbially oxidized arsenopyrite. Intermediates, such as Fe(III)-AsS and S0, were detectable in the presence of bacteria. Changes of oxidative species derived from XPS depth profiles show the oxidation sequence is Fe > As = S in abiotic oxidation, and Fe > S > As in microbial oxidation. Based on these results, a possible reaction path of microbial oxidation was proposed in a concept model.

Zhu, Tingting; Lu, Xiancai; Liu, Huan; Li, Juan; Zhu, Xiangyu; Lu, Jianjun; Wang, Rucheng

2014-02-01

256

QUANTITATIVE SPECTROSCOPY OF BLUE SUPERGIANT STARS IN THE DISK OF M81: METALLICITY, METALLICITY GRADIENT, AND DISTANCE  

SciTech Connect

The quantitative spectral analysis of low-resolution ({approx}5 A) Keck LRIS spectra of blue supergiants in the disk of the giant spiral galaxy M81 is used to determine stellar effective temperatures, gravities, metallicities, luminosities, interstellar reddening, and a new distance using the flux-weighted gravity-luminosity relationship. Substantial reddening and extinction are found with E(B - V) ranging between 0.13 and 0.38 mag and an average value of 0.26 mag. The distance modulus obtained after individual reddening corrections is 27.7 {+-} 0.1 mag. The result is discussed with regard to recently measured tip of the red giant branch and Cepheid distances. The metallicities (based on elements such as iron, titanium, magnesium) are supersolar ( Almost-Equal-To 0.2 dex) in the inner disk (R {approx}< 5 kpc) and slightly subsolar ( Almost-Equal-To - 0.05 dex) in the outer disk (R {approx}> 10 kpc) with a shallow metallicity gradient of 0.034 dex kpc{sup -1}. The comparison with published oxygen abundances of planetary nebulae and metallicities determined through fits of Hubble Space Telescope color-magnitude diagrams indicates a late metal enrichment and a flattening of the abundance gradient over the last 5 Gyr. This might be the result of gas infall from metal-rich satellite galaxies. Combining these M81 metallicities with published blue supergiant abundance studies in the Local Group and the Sculptor Group, a galaxy mass-metallicity relationship based solely on stellar spectroscopic studies is presented and compared with recent studies of Sloan Digital Sky Survey star-forming galaxies.

Kudritzki, Rolf-Peter; Urbaneja, Miguel A.; Gazak, Zachary; Bresolin, Fabio [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Przybilla, Norbert [Dr. Remeis-Sternwarte Bamberg and ECAP, D-96049 Bamberg (Germany); Gieren, Wolfgang; Pietrzynski, Grzegorz, E-mail: kud@ifa.hawaii.edu, E-mail: urbaneja@ifa.hawaii.edu, E-mail: zgazak@ifa.hawaii.edu, E-mail: bresolin@ifa.hawaii.edu, E-mail: przybilla@sternwarte.uni-erlangen.de, E-mail: wgieren@astro-udec.cl, E-mail: pietrzyn@astrouw.edu.pl [Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)

2012-03-01

257

Experimental and theoretical studies of (FTIR, FT-NMR, UV-Visible, X-ray and DFT) 2-(4-Allyl-5-pyridin-4-yl-4H-[1,2,4]triazol-3-ylsulfanyl)-1-(3-methyl-3-phenyl-cyclobutyl)-ethanone  

NASA Astrophysics Data System (ADS)

The single crystal structure, 2-(4-Allyl-5-pyridin-4-yl-4H-[1,2,4]triazol-3-ylsulfanyl)-1-(3-methyl-3-phenyl-cyclobutyl)-ethanone, has been synthesized and characterized by IR, NMR, UV spectra and X-ray diffraction methods. In addition, the optimized structure, the vibrational assignments, the chemical shifts, the molecular orbital energies, molecular electrostatic potential maps and thermodynamic properties, ionization potential, electron affinity, electronegativity, global chemical hardness and chemical softness of the molecule have been investigated by using Density Functional Theory with B3LYP/6-31G(d) and B3LYP/6-311G(d, p) basis sets. UV-Visible spectrum of the compound was recorded and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. The observed results of the compound have been compared with theoretical results and it is found that the experimental data show good agreement with calculated values. The single crystal structure of the compound crystallizes in the monoclinic system with space group C 2/c.

Ataol, Çi?dem Yüksektepe; Ekici, Öner

2014-05-01

258

AUGER ELECTRON SPECTROSCOPY  

E-print Network

Qualitative Chemical Analysis by AES Auger electronAuger electron spectroscopy can provide quantitative chemical analysischemical analysis can be performed. Since both the adsorbate and the substrate Auger

Somorjai, G.A.

2010-01-01

259

Time-Resolved Quantitative Measurement of OH HO2 and CH2O in Fuel Oxidation Reactions by High Resolution IR Absorption Spectroscopy.  

SciTech Connect

Combined with a Herriott-type multi-pass slow flow reactor, high-resolution differential direct absorption spectroscopy has been used to probe, in situ and quantitatively, hydroxyl (OH), hydroperoxy (HO 2 ) and formaldehyde (CH 2 O) molecules in fuel oxidation reactions in the reactor, with a time resolution of about 1 micro-second. While OH and CH 2 O are probed in the mid-infrared (MIR) region near 2870nm and 3574nm respectively, HO 2 can be probed in both regions: near-infrared (NIR) at 1509nm and MIR at 2870nm. Typical sensitivities are on the order of 10 10 - 10 11 molecule cm -3 for OH at 2870nm, 10 11 molecule cm -3 for HO 2 at 1509nm, and 10 11 molecule cm -3 for CH 2 O at 3574nm. Measurements of multiple important intermediates (OH and HO 2 ) and product (CH 2 O) facilitate to understand and further validate chemical mechanisms of fuel oxidation chemistry.

Huang, Haifeng; Rotavera, Brandon; Taatjes, Craig A.

2014-08-01

260

Quantitative characterization of optical and physiological parameters in normal breasts using time-resolved spectroscopy: in vivo results of 19 Singapore women  

NASA Astrophysics Data System (ADS)

We report the quantitative measurements of optical and physiological parameters of normal breasts from 19 Singapore women by using time-resolved diffuse optical spectroscopy. Intrinsic absorption coefficient (?a) and reduced scattering coefficients (?s') of breasts were calculated from the time-resolved photon migration data. Physiology of breasts was characterized using the concentrations of oxyhemoglobin, deoxyhemoglobin, total hemoglobin (THC), and oxygenation saturation. On average, the experiment results showed that the ?a of young women (below 40 years old) was 36 to 38% greater than that of older women (above 40 years old) and that parameter THC was approximately 42% greater. Results also showed that the THC of premenopausal women was 24.3 ?Mol/L, which was approximately 69% larger than that of postmenopausal women at 14.1 ?Mol/L. Meanwhile, the ?a of premenopausal women was approximately 60% larger than that of postmenopausal women. Correlation analysis further showed that the optical and physiological parameters of breasts were strongly influenced by changes in the women's age, menopausal states, and body mass index. These in vivo experiment results will contribute to the breast tissue diagnosis between healthy and diseased breast tissues.

Mo, Weirong; Chan, Tryphena S. S.; Chen, Ling; Chen, Nanguang

2009-11-01

261

Spectroscopy study of silver nanoparticles fabrication using synthetic humic substances and their antimicrobial activity.  

PubMed

In this present study, silver nanoparticles were synthesized using synthetic humic substances (HSs) as reducing and stabilizing agents. Preference of synthetic HSs over natural humic matter is determined by a standardization problem resolution of the product due to the strict control of conditions of the synthetic HSs formation. It allows to receive the silver nanoparticles with the standardized biologically-active protective shell that is very important for their use, mainly in medicine. The concentration of sodium hydroxide, synthetic HSs, silver nitrate and temperature employed in the synthesis process are optimized to attain better yield, controlled size and stability by means of UV-visible technique. In the optimal reaction conditions the concentrated silver colloids (55 mM) with 99.99% yield are obtained which were stable for more than 1 year under ambient conditions. The received silver nanoparticles are characterized by UV-visible spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). The antimicrobial activity of silver nanoparticles against fungal and bacterial strains is also shown. PMID:23466321

Litvin, Valentina A; Minaev, Boris F

2013-05-01

262

Evolution of Instrumentation for UV-Visible Spectrophotometry. Part I.  

ERIC Educational Resources Information Center

Traces the development of instruments used in spectrophotometry. Discusses how spectrophotometric measurements are made. Describes the color comparator, the filter photometer, and the spectrophotometer. Outlines the evolution of optical systems, including light sources, the monochromator, the photodetector, double-beam optics, and split-beam…

Altemose, Ines R.

1986-01-01

263

New developments for vidicon-based uv-visible spectrometers  

Microsoft Academic Search

Potential applicability of the multi-level vidicon spectrometer presented to analytical problems was illustrated by the examination of three chemical systems involving lanthanide oxides, serum protein, and bromothymol blue. Data from the spectrometer coupled with a multiwavelength multicomponent simultaneous analysis technique resulted in a measured pKa of 7.05 for bromothymol blue and exhibited promise for the analysis of total serum protein

R. M. Hoffman

1978-01-01

264

Application of NIR spectroscopy for the quality control of mangosteen pericarp powder: quantitative analysis of alpha-mangostin in mangosteen pericarp powder and capsule.  

PubMed

Near-infrared spectroscopy (NIR) was applied to the quantitative analysis of the concentration of alpha-mangostin (aM) in mangosteen pericarp powder (MP). The predicted results from the partial least squares chemometric method of various pretreatment data were compared to obtain the best calibration model. Two different types of containers (transparent capsules and glass vials) filled with the same samples were measured. For MP mixture in vials, the calibration model involving nine principal components (PC) could predict the amount of aM most accurately based on non-pretreatment spectral data. For MP mixture in capsules, the calibration model involving nine PC could predict the amount of aM most accurately based on first-derivative pretreatment spectra. The relationships of the calibration models for both samples had sufficiently linear plots. The standard error of cross-validation for the MP mixture in vials was lower and the R(2) values of validation were higher compared to the MP mixture in capsules. The equation for prediction of the concentration of aM in MP mixtures in vials is y = 0.9775x + 0.0425 with R(2) = 0.9950 and for those in capsules is y = 1.0264x + 0.0126 with R(2) = 0.9898. Both validation results indicated that the concentrations of aM in MP mixtures were predicted with sufficient accuracy and repeatability. NIR can be a useful tool for the quality control of herbal medicine in powder form without any sample preparation. The type and the shape of the container should be considered to obtain more accurate data. PMID:22926311

Peerapattana, Jomjai; Otsuka, Kuniko; Otsuka, Makoto

2013-07-01

265

Chiroptical Spectroscopy  

NASA Astrophysics Data System (ADS)

A brief review of the literature, and Chemical and Engineering News in particular, reveals that the determination and use of optical activity is of increasing importance in today's commercial and research laboratories. The classical technique is to measure [alpha]D using a manual or recording polarimeter to provide a single value, the specific rotation at 589 nm. A spectropolarimeter can be used to determine optical activity through the UV-Visible spectrum (Optical Rotatory Dispersion [ORD]). At wavelengths far removed from electronic absorption bands, optical activity arises from circular birefringence, or the difference in the refractive index for left- and right-circularly polarized light; i.e., nL - nR does not equal zero for chiral materials. If the optical activity is measured through an absorption band, complex behavior is observed (a Cotton Effect curve). At an absorption band, chiral materials exhibit circular dichroism (CD), or a difference in the absorption of left- and right-circularly polarized light; epsilon L minus epsilon R does not equal zero. If the spectropolarimeter is set for the measurement of CD spectra, one observes what appears to be a UV-Vis spectrum except that some absorption bands are positive while others may be negative. Just as enantiomers have specific rotations that are equal and opposite at 589 nm (sodium D line), rotations are equal and opposite at all wavelengths, and CD measurements are equal and opposite at all wavelengths. Figure 1 shows the ORD curves for the enantiomeric carvones while Figure 2 contains the CD curves. The enantiomer of carvone that has the positive [alpha]D is obtained from caraway seeds and is known to have the S-configuration while the R-enantiomer is found in spearmint oil. Figure 1. ORD of S-(+)- and R-(-)-carvones Figure 2. CD of S-(+)- and R-(-)-carvones While little can be done to correlate stereochemistry with [alpha]D values, chiroptical spectroscopy (ORD and/or CD) often can be used to assign absolute or relative configuration, or it can be useful in conformational analyses (1). Experiments are being developed for undergraduates that involve the synthesis of chiral materials, or the resolution of chiral materials, including organic compounds, inorganic complexes and organometallic compounds. Both classical and chiral HPLC resolutions are being tested. Once prepared, these chiral materials are studied by various techniques including NMR, Raman, IR, UV-VIS, differential scanning calorimetry (DSC), and chiroptical techniques. Molecular mechanics calculations are included (using PCModel which is available from Serena Software, Bloomington, IN.) when appropriate. Examples include some traditional experiments; i.e., the preparation and resolution of the tris-ethylenediaminecobalt complexes as well as some not now found in typical undergraduate laboratory manuals. For example, the resolution of trans-1,2-diaminocyclohexane and subsequent conversion to the bis-Schiff base with para-dimethylamino-benzaldehyde. These Schiff bases have been studied by Nakanishi (2) using the exciton coupling method. AcknowledgmentThis work was supported partially under the award DUE-9351122 from the National Science Foundation Division of Undergraduate Education Instrumentation and Laboratory Improvement Program. Literature Cited Eliel, E.; Wilen, S. H. Stereochemistry of Organic Compounds; J. Wiley & Sons, Inc.: New York, 1994; Djerassi, C. Optical Rotary Dispersion; McGraw-Hill Book Company, Inc., New York, 1960.; Crabbe, P. Optical Rotary Dispersion and Circular Dichroism in Organic Chemistry; Holden-Day: San Francisco, 1965. Gargiulo, D.; Cai, G.; Ikemoto, N.; Bozhkova, N.; Odingo, J. Berova, N. Nakanishi, K. Angew. Chemie Int. Ed. Engl. 1993, 32, 888-891.

Gurst, Jerome E.

1995-09-01

266

Phthalocyanine identification in paintings by reflectance spectroscopy. A laboratory and in situ study  

NASA Astrophysics Data System (ADS)

The importance of identifying pigments using non invasive (n.i.) analyses has gained increasing importance in the field of spectroscopy applied to art conservation and art studies. Among the large set of pigments synthesized and marketed during 20th century, surely phthalocyanine blue and green pigments occupy an important role in the field of painting (including restoration) and printing, thanks to their characteristics like brightness and fastness. This research focused on the most used phthalocyanine blue (PB15:1 and PB15:3) and green pigments (PG7), and on the possibility to identify these organic compounds using a methodology like reflectance spectroscopy in the UV, visible and near IR range (UV-vis-NIR RS), performed easily through portable instruments. Laboratory tests and three examples carried out on real paintings are discussed.

Poldi, G.; Caglio, S.

2013-06-01

267

Oriented single-crystal nuclear resonance vibrational spectroscopy of [Fe(TPP)(MI)(NO)] : quantitative sssessment of the trans effect of NO.  

SciTech Connect

This paper presents oriented single-crystal Nuclear Resonance Vibrational Spectroscopy (NRVS) data for the six-coordinate (6C) ferrous heme-nitrosyl model complex [{sup 57}Fe(TPP)(MI)(NO)] (1; TPP{sup 2-} = tetraphenylporphyrin dianion; MI = 1-methylimidazole). The availability of these data enables for the first time the detailed simulation of the complete NRVS data, including the porphyrin-based vibrations, of a 6C ferrous heme-nitrosyl, using our quantum chemistry centered normal coordinate analysis (QCC-NCA). Importantly, the Fe-NO stretch is split by interaction with a porphyrin-based vibration into two features, observed at 437 and 472 cm{sup -1}. The 437 cm{sup -1} feature is strongly out-of-plane (oop) polarized and shows a {sup 15}N{sup 18}O isotope shift of 8 cm{sup -1} and is therefore assigned to v(Fe-NO). The admixture of Fe-N-O bending character is small. Main contributions to the Fe-N-O bend are observed in the 520-580 cm{sup -1} region, distributed over a number of in-plane (ip) polarized porphyrin-based vibrations. The main component, assigned to {delta}{sub ip}(Fe-N-O), is identified with the feature at 563 cm{sup -1}. The Fe-N-O bend also shows strong mixing with the Fe-NO stretching internal coordinate, as evidenced by the oop NRVS intensity in the 520-580 cm{sup -1} region. Very accurate normal mode descriptions of ?(Fe-NO) and {delta}{sub ip}(Fe-N-O) have been obtained in this study. These results contradict previous interpretations of the vibrational spectra of 6C ferrous heme-nitrosyls where the higher energy feature at {approx}550 cm{sup -1} had usually been associated with v(Fe-NO). Furthermore, these results provide key insight into NO binding to ferrous heme active sites in globins and other heme proteins, in particular with respect to (a) the effect of hydrogen bonding to the coordinated NO and (b) changes in heme dynamics upon NO coordination. [Fe(TPP)(MI)(NO)] constitutes an excellent model system for ferrous NO adducts of myoglobin (Mb) mutants where the distal histidine (His64) has been removed. Comparison to the reported vibrational data for wild-type (wt) Mb-NO then shows that the effect of H bonding to the coordinated NO is weak and mostly leads to a polarization of the {pi}/{pi}* orbitals of bound NO. In addition, the observation that {delta}{sub ip}(Fe-N-O) does not correlate well with ?(N-O) can be traced back to the very mixed nature of this mode. The Fe-N(imidazole) stretching frequency is observed at 149 cm{sup -1} in [Fe(TPP)(MI)(NO)], and spectral changes upon NO binding to five-coordinate ferrous heme active sites are discussed. The obtained high-quality force constants for the Fe-NO and N-O bonds of 2.57 and 11.55 mdyn/{angstrom} can further be compared to those of corresponding 5C species, which allows for a quantitative analysis of the {sigma} trans interaction between the proximal imidazole (His) ligand and NO. This is key for the activation of the NO sensor soluble guanylate cyclase. Finally, DFT methods are calibrated against the experimentally determined vibrational properties of the Fe-N-O subunit in 1. DFT is in fact incapable of reproducing the vibrational energies and normal mode descriptions of the Fe-N-O unit well, and thus, DFT-based predictions of changes in vibrational properties upon heme modification or other perturbations of these 6C complexes have to be treated with caution.

Lehnert, N.; Sage, J. T.; Silvernail, N.; Scheidt, W. R.; Alp, E. E.; Sturhahn, W.; Zhao, J. (X-Ray Science Division); (Univ. of Michigan); (Northeastern Univ.); (Univ. of Notre Dame)

2010-01-01

268

In-situ Optical Spectroscopy Investigation of Water and Its influence on Forsterite Transformation in Supercritical CO2  

NASA Astrophysics Data System (ADS)

Carbon capture and sequestration (CCS) from coal/gas-burning power plants is currently viewed as one of the most promising technologies for mitigating green house gas emissions. This strategy involves injection of supercritical CO2 (scCO2) into deep geological formations such as depleted oil and gas reservoirs and deep saline aquifers. The feasibility of this approach and the ultimate fate of the stored CO2 are determined by the interactions between scCO2, various minerals in the rock formations, and the host fluids. Currently, there is only limited knowledge about both the thermodynamic and kinetic aspects of the physical and chemical processes that occur between scCO2 and relevant minerals, such as metal silicates and metal aluminosilicates, and the role of water activity for catalyzing mineral transformation reactions. In this work, we have developed a modular in situ optical spectroscopic platform that integrates a scCO2 generation and manipulation system with an array of optical and laser spectroscopies including UV-visible, IR, Raman and laser fluorescence spectroscopy. We have used the system to study i) the dissolution and quantification of H2O/D2O in scCO2 and ii) interaction between scCO2 and a model metal silicate, forsterite (Mg2SiO4), and the effects of the presence of water under variable pressure, temperature and water content. Our results showed that H2O and D2O have unique IR spectral features over a broad spectral range from 700 cm-1 to ~ 2900 cm-1 in scCO2 and their concentrations are directly proportional to the characteristic IR bands that correspond to their stretching (D2O) and bending frequencies (both D2O and H2O). These bands offer a unique spectroscopic signature useful for qualitative and quantitative analysis of the properties and reactivity of small amounts of H2O in scCO2.

Wang, Z.; Thompson, C. J.; Joly, A. G.; Sklarew, D. S.; Poindexter, L.; Rosso, K. M.

2009-12-01

269

Quantitative estimation of NH3 partial pressure in H2 desorbed from the Li-N-H system by Raman spectroscopy.  

PubMed

The partial pressure of NH3 gas estimated by Raman spectroscopy indicates that approximately 0.1% NH3 inevitably contaminates the H2 desorbed from a hydrogen storage material composed of LiH and LiNH2 at any temperature up to 400 degrees C in a closed system. PMID:15959577

Hino, Satoshi; Ichikawa, Takayuki; Ogita, Norio; Udagawa, Masayuki; Fujii, Hironobu

2005-06-28

270

Nanostructural Differentiation between Live and Dead Escherichia coli Cells Using FT-IR Spectroscopy and Comparison of Detection Limits to Quantitative PCR (qPCR)  

Microsoft Academic Search

Fourier-transform infrared spectroscopy (FT-IR) utilizes nanostructural differences between bacterial cells for the rapid identification, classification, and differentiation of many species of bacteria, but most studies have used only live cells. A rapid and reliable method for determining the total number of live and dead bacterial cells in a food could prevent the distribution of unsafe products to consumers. In this

A. J. Deering; B. L. Reuhs; L. J. Mauer

2010-01-01

271

Use of near infrared correlation spectroscopy for quantitation of surface iron, absorbed water and stored electronic energy in a suite of Mars soil analog materials  

NASA Technical Reports Server (NTRS)

A number of questions concerning the surface mineralogy and the history of water on Mars remain unresolved using the Viking analyses and Earth-based telescopic data. Identification and quantitation of iron-bearing clays on Mars would elucidate these outstanding issues. Near infrared correlation analysis, a method typically applied to qualitative and quantitative analysis of individual constituents of multicomponent mixtures, is adapted here to selection of distinctive features of a small, highly homologous series of Fe/Ca-exchanged montmorillonites and several kalinites. Independently determined measures of surface iron, relative humidity and stored electronic energy were used as constituent data for linear regression of the constituent vs. reflectance data throughout the spectral region 0.68 to 2.5 micrometers. High correlations were found in appropriate regions for all three constituents, though that with stored energy is still considered tenuous. Quantitation was improved using 1st and 2nd derivative spectra. High resolution data over a broad spectral range would be required to quantitatively identify iron-bearing clays by remotely sensed reflectance.

Coyne, Lelia M.; Banin, Amos; Carle, Glenn; Orenberg, James; Scattergood, Thomas

1989-01-01

272

Implementation of Traditional and Real-World Cooperative Learning Techniques in Quantitative Analysis Including Near Infrared Spectroscopy for Analysis of Live Fish  

Microsoft Academic Search

It is important for a modern quantitative analysis laboratory course to contain gravimetric and volumetric analysis exercises implemented with standard unknowns. By analyzing unknowns, students learn crucial laboratory skills. It is also advantageous to introduce real-world samples and cooperative learning structure into the lab course. A one-semester sophomore course at Idaho State University is divided into two parts: students individually

Tracy P. Houghton; John H. Kalivas

2000-01-01

273

Fluorescence spectroscopy of kerosene vapour at high temperatures and pressures: potential for gas turbines measurements  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence spectroscopy of kerosene vapour was performed in a heated test cell operating between 450 and 900 K, at pressure from 0.1 to 3.0 MPa, for oxygen molar fraction between 0 and 21 %, with different laser excitation wavelengths (248, 266, 282 and 308 nm). Results show that, depending on the laser excitation scheme, kerosene fluorescence spectrum exhibits one or two fluorescence bands in the UV-visible range (attributed to aromatics naturally present in kerosene fuel). Fluorescence intensity of these bands decreases with increasing temperature, pressure and oxygen molar fraction. Different imaging strategies were derived from spectroscopic findings to simultaneously measure temperature and equivalence ratio fields in kerosene/air sprays, or flame structure and fuel spatial distribution in kerosene/air aeronautical combustors, by means of planar laser-induced fluorescence on kerosene vapour (K-PLIF).

Orain, M.; Baranger, P.; Ledier, C.; Apeloig, J.; Grisch, F.

2014-09-01

274

Synthesis, characterization, spectroscopy, electronic and redox properties of a new nickel dithiolene system  

PubMed Central

A new dithiolene ligand with 3,5-dibromo substituted phenyl groups was designed and synthesized. The protected form of the ligand was reacted with a nickel salt providing neutral Ni(S2C2(3,5-C6H3Br2)2)2 and anionic [Ni(S2C2(3,5-C6H3Br2)2)2]? isolated as a Bu4N+ salt. Both were characterized by UV-visible and IR spectroscopy and compared with the similar known molecular systems. They exhibit intense low-energy transitions that are characteristic of such systems. The electrochemical behavior of these molecules was investigated by cyclic voltammetry. PMID:21057604

Basu, Partha; Nigam, Archana; Mogesa, Benjamin; Denti, Suzanne; Nemykin, Victor

2010-01-01

275

Quantitative determination of iron oxidation states in minerals using Fe L 2,3 -edge electron energy-loss near-edge structure spectroscopy  

Microsoft Academic Search

The Fe L\\u000a 2,3-edge spectra for a range of natural minerals and synthetic solid solutions have been measured using the technique of parallel\\u000a electron energy-loss spectroscopy (PEELS) recorded in a transmission electron microscope (TEM). The Fe L\\u000a \\u000a 2,3\\u000a -edges of the minerals are characterised by two white-line features and exhibit electron energy-loss near-edge structure (ELNES)\\u000a characteristic of Fe valence state.

P. A. van Aken; B. Liebscher; V. J. Styrsa

1998-01-01

276

Undergraduate Quantitative  

E-print Network

Undergraduate Quantitative Research Methods with: Childhood Studies | Geography | Politics | Social.ac.uk/study The University of Bristol is introducing a new quantitative research methods pathway to a range of social science new courses, work placements and pathways to Why enhance your degree with quantitative research

Bristol, University of

277

A quantitative study of valence electron transfer in the skutterudite compound CoP(3) by combining x-ray induced Auger and photoelectron spectroscopy.  

PubMed

We use the sum of the ionization and Auger energy, the so-called Auger parameter, measured from the x-ray photoelectron spectrum, to study the valence electron distribution in the skutterudite CoP(3). The electron transfer between Co and P was estimated using models relating changes in Auger parameter values to charge transfer. It was found that each P atom gains 0.24 e(-), and considering the unit formula CoP(3) this is equivalent to a donation of 0.72 e(-) per Co atom. This is in agreement with a recent electron energy-loss spectroscopy study, which indicates a charge transfer of 0.77 e(-)/atom from Co to P. PMID:21694059

Diplas, S; Prytz, O; Karlsen, O B; Watts, J F; Taftø, J

2007-06-20

278

Prostate Cancer Metastases Alter Bone Mineral and Matrix Composition Independent of Effects on Bone Architecture in Mice A Quantitative Study Using microCT and Raman Spectroscopy  

PubMed Central

Prostate cancer is the most common primary tumor and the second leading cause of cancer-related deaths in men in the United States. Prostate cancer bone metastases are characterized by abnormal bone remodeling processes and result in a variety of skeletal morbidities. Prevention of skeletal complications is a crucial element in prostate cancer management. This study investigated prostate cancer-induced alterations in the molecular composition and morphological structure of metastasis-bearing bones in a mouse model of prostate cancer using Raman spectroscopy and micro-computed tomography (microCT). LNCaP C4-2B prostate cancer cells were injected into the right tibiae of 5-week old male SCID mice. Upon sacrifice at 8 weeks post tumor inoculation, two out of the ten tumor-bearing tibiae showed only osteoblastic lesions in the radiographs, 4 osteolytic lesions only and 4 mixed with osteoblastic and osteolytic lesions.. Carbonate substitution was significantly increased while there was a marked reduction in the level of collagen mineralization, mineral crystallinity, and carbonate:matrix ratio in the cortex of the intact tumor-bearing tibiae compared to contralateral controls. MicroCT analysis revealed a significant reduction in bone volume/total volume, trabecular number and trabecular thickness, as well as significant increase in bone surface/volume ratio in tibiae with osteolytic lesions, suggesting active bone remodeling and bone loss. None of the changes in bone compositional properties were correlated with lesion area from radiographs or the changes in bone architecture from microCT. This study indicates that LNCaP C4-2B prostate cancer metastases alter bone tissue composition independent of changes in architecture, and altered bone quality may be an important contributor to fracture risk in these patients. Raman spectroscopy may provide a new avenue of investigation into interactions between tumor and bone microenvironment. PMID:23867219

Bi, Xiaohong; Sterling, Julie A.; Merkel, Alyssa R.; Perrien, Daniel S.; Nyman, Jeffry; Mahadevan-Jansen, Anita

2013-01-01

279

Quantitative use of electron energy-loss spectroscopy Mo-M2,3 edges for the study of molybdenum oxides.  

PubMed

Because of the large energy separation between O-K and Mo-L2,3 edges, extracting precise and reliable chemical information from core-loss EELS analyze of molybdenum oxides has always been a challenge. In this regard Mo-M2,3 edges represents an interesting alternative as they are situated close to the O-K edges. They should allow thus the extraction of a wealth of chemical information from the same spectra. However the main difficulty to overcome in order to work properly with these edges is the delayed maxima of the Mo-M4,5 edges which hinders the automated background subtraction with the usual inverse power low function. In this study we propose another background subtraction method specifically designed to overcome this obstacle and we apply it to the study of MoO3 and MoO2. We are able to show that quantitative chemical information can be precisely and accurately determined from the joined analyze of O-K and Mo-M2,3 edges. In particular k-factors are derived as a function of the integration window width and standard errors close to 2% are reported. The possibility to discriminate the two oxides thanks to chemical shifts and energy-loss near-edge structures is also investigated and discussed. Furthermore the M3/M2 ratios are derived and are found to be strongly dependent on the local chemical environment. This result is confirmed by multiplet calculations for which the crystal field parameters have been determined by ab initio calculations. The whole methodology as well as the conclusions presented in this paper should be easily transposable to any transitions metal oxides of the 4d family. This work should open a new and easier way regarding the quantitative EELS analyses of these compounds. PMID:25464154

Lajaunie, L; Boucher, F; Dessapt, R; Moreau, P

2015-02-01

280

Quantitative assessment of brain tissue oxygenation in porcine models of cardiac arrest and cardiopulmonary resuscitation using hyperspectral near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Near-infrared spectroscopy (NIRS) is a non-invasive tool to measure real-time tissue oxygenation in the brain. In an invasive animal experiment we were able to directly compare non-invasive NIRS measurements on the skull with invasive measurements directly on the brain dura matter. We used a broad-band, continuous-wave hyper-spectral approach to measure tissue oxygenation in the brain of pigs under the conditions of cardiac arrest, cardiopulmonary resuscitation (CPR), and defibrillation. An additional purpose of this research was to find a correlation between mortality due to cardiac arrest and inadequacy of the tissue perfusion during attempts at resuscitation. Using this technique we measured the changes in concentrations of oxy-hemoglobin [HbO2] and deoxy-hemoglobin [HHb] to quantify the tissue oxygenation in the brain. We also extracted cytochrome c oxidase changes ?[Cyt-Ox] under the same conditions to determine increase or decrease in cerebral oxygen delivery. In this paper we proved that applying CPR, [HbO2] concentration and tissue oxygenation in the brain increase while [HHb] concentration decreases which was not possible using other measurement techniques. We also discovered a similar trend in changes of both [Cyt-Ox] concentration and tissue oxygen saturation (StO2). Both invasive and non-invasive measurements showed similar results.

Lotfabadi, Shahin S.; Toronov, Vladislav; Ramadeen, Andrew; Hu, Xudong; Kim, Siwook; Dorian, Paul; Hare, Gregory M. T.

2014-03-01

281

Easy and cheap fabrication of ordered pyramidal-shaped plasmonic substrates for detection and quantitative analysis using surface-enhanced Raman spectroscopy.  

PubMed

In this work we present a simple approach for the fabrication of periodically ordered pyramidal-shaped metallic nanostructures and demonstrate their efficiency as SERS active substrates. Our method for the fabrication of the plasmonic substrate is based on nanoimprint lithography and exploits the thermal properties of two classes of polymers, thermoplastics and hydrogels. During the heating process the thermoplastic polymers will start to melt whereas the hydrogel polymers will form a solid due to the evaporation of water molecules adsorbed during the dissolving process. Using this approach we fabricate highly ordered pyramidal-shaped nanostructures using the texture of a commercial DVD as the initial mold. This technique represents a low-cost alternative to the classical lithography techniques, allowing the fabrication over large areas (~cm(2)) of periodically ordered nanostructures in a controlled and reproducible manner. The SERS efficiency of the fabricated substrate is demonstrated through the detection of urea molecules found in the fingerprint. In addition, due to the periodicity of the pyramidal-shaped structures, the fabricated substrate can be successfully employed to correlate the intensity of the specific SERS peak of urea with the molecules concentration, offering thus the possibility of developing a quantitative SERS renal sensor. PMID:23817626

Leordean, Cosmin; Gabudean, Ana-Maria; Canpean, Valentin; Astilean, Simion

2013-09-01

282

Influence of picosecond multiple/single line ablation on copper nanoparticles fabricated for surface enhanced Raman spectroscopy and photonics applications  

NASA Astrophysics Data System (ADS)

A comprehensive study comprising fabrication of copper nanoparticles (NPs) using picosecond (ps) multiple/single line ablation in various solvents such as acetone, dichloromethane (DCM), acetonitrile (ACN) and chloroform followed by optical, nonlinear optical (NLO), and surface enhanced Raman spectroscopy (SERS) characterization was performed. The influence of surrounding liquid media and the writing conditions resulted in fabrication of Cu NPs in acetone, CuCl NPs in DCM, CuO NPs in ACN and CuCl2 NPs in chloroform. Prepared colloids were characterized through transmission electron microscopy, energy dispersive x-ray spectra, selected area electron diffraction and UV-visible absorption spectra. A detailed investigation of the surface enhanced Raman scattering (SERS) activity and the ps NLO properties of the colloids prepared through multiple/single line ablation techniques revealed that the best performance was achieved by Cu NPs for SERS applications and CuCl2 NPs for NLO applications.

Hamad, Syed; Krishna Podagatlapalli, G.; Tewari, Surya P.; Venugopal Rao, S.

2013-12-01

283

Quantitative spatially resolved measurement of tissue chromophore concentrations using photoacoustic spectroscopy: application to the measurement of blood oxygenation and haemoglobin concentration.  

PubMed

A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO(2)) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO(2)) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO(2) and HHb, total haemoglobin concentration and SO(2). The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of +/-3.8 g l(-1) (+/-58 microM) and +/-4.4 g l(-1) (+/-68 microM) for the HbO(2) and HHb concentrations respectively and +/-4% for SO(2) with an accuracy in the latter in the range -6%-+7%. PMID:17183133

Laufer, Jan; Delpy, Dave; Elwell, Clare; Beard, Paul

2007-01-01

284

Relationship between the v2PO4/amide III ratio assessed by Raman spectroscopy and the calcium content measured by quantitative backscattered electron microscopy in healthy human osteonal bone  

NASA Astrophysics Data System (ADS)

Raman microspectroscopy and quantitative backscattered electron imaging (qBEI) of bone are powerful tools to investigate bone material properties. Both methods provide information on the degree of bone matrix mineralization. However, a head-to-head comparison of these outcomes from identical bone areas has not been performed to date. In femoral midshaft cross sections of three women, 99 regions (20×20 ?) were selected inside osteons and interstitial bone covering a wide range of matrix mineralization. As the focus of this study was only on regions undergoing secondary mineralization, zones exhibiting a distinct gradient in mineral content close to the mineralization front were excluded. The same regions were measured by both methods. We found a linear correlation (R2=0.75) between mineral/matrix as measured by Raman spectroscopy and the wt. %Mineral/(100-wt. %Mineral) as obtained by qBEI, in good agreement with theoretical estimations. The observed deviations of single values from the linear regression line were determined to reflect biological heterogeneities. The data of this study demonstrate the good correspondence between Raman and qBEI outcomes in describing tissue mineralization. The obtained correlation is likely sensitive to changes in bone tissue composition, providing an approach to detect potential deviations from normal bone.

Roschger, Andreas; Gamsjaeger, Sonja; Hofstetter, Birgit; Masic, Admir; Blouin, Stéphane; Messmer, Phaedra; Berzlanovich, Andrea; Paschalis, Eleftherios P.; Roschger, Paul; Klaushofer, Klaus; Fratzl, Peter

2014-06-01

285

Spectroscopy of divertor plasmas  

SciTech Connect

The requirements for divertor spectroscopy are treated with respect to instrumentation and observations on present machines. Emphasis is placed on quantitative measurements.of impurity concentrations from the interpretation of spectral line intensities. The possible influence of non-Maxwellian electron distributions on spectral line excitation in the divertor is discussed. Finally the use of spectroscopy for determining plasma temperature, density, and flows is examined.

Isler, R.C.

1995-12-31

286

Fiber Laser Based Nonlinear Spectroscopy  

E-print Network

practical. A nonlinear spectroscopy tool based on a single fiber laser, with electrically controlled wavelength-tuning and spectral resolution enhanced by a pulse shaping technique, will efficiently produce optical excitation that allows quantitative...

Adany, Peter

2012-08-31

287

Quantitative NMR  

NSDL National Science Digital Library

This site features a learning module focused on principles and practice of NMR for quantitative analysis, an application less commonly associated with the technique than is structure determination. Links to simulation packages are included.

Korir, Albert K.; Larive, Cynthia K.

2011-07-18

288

Characterisation of dissolved organic matter (DOM) in the Seine River catchment (France) by excitation-emission matrix (EEM) fluorescence spectroscopy combined with PARAFAC and PCA analyses  

NASA Astrophysics Data System (ADS)

Dissolved organic matter (DOM) is a heterogeneous, complex mixture of compounds with wide ranging chemical properties and diverse origins. It is well known to interact with pollutants and to affect their transport and their fate in aquatic environment, and plays a vital role in the global cycling of carbon. In this study, UV/visible absorbance and excitation emission matrix (EEM) fluorescence spectroscopy combined with PARAFAC and PCA analyses have been used to characterize colloidal DOM in the Seine River watershed. Surface water samples were collected in November 2011, September 2012 (low-water) and February 2013 (flood) from 23, 39 and 45 sites respectively from different areas including the Oise basin, the Marne basin, the Grand Morin basin and the downstream of the Seine River. A Jasco V-560 spectrophotometer was used for UV/visible absorbance measurement. Fluorescence spectra were recorded using a Fluorolog FL3-22 SPEX - JOBIN YVON fluorometer. The samples, at natural pH, were placed in 1 cm quartz cuvette, thermostated at 20°C. All sample spectra were obtained by subtracting a blank spectrum (ultrapure water Milli-Q, Millipore) and were instrumentally corrected. When necessary, samples were diluted to avoid inner filter effects. The fluorescence data set was analyzed using PARAFAC DOMFluor toolbox in Matlab which decomposes the complex data matrix into its main components. The application of UV/visible absorbance and EEM fluorescence spectroscopy in combination with PARAFAC and PCA analyses allowed us to identify different sources of dissolved organic matter in the catchment of the Seine River and highlighted spatial and temporal variations of DOM properties. We observed significant different and specific typologies of organic matter for the four studied zones. The Seine basin is characterized by the strongest biological activity (in connection with the presence of the "Seine-Aval" WWTP). DOM from the Oise basin seems to have more "humic" characteristics (a forest sample presenting the strongest "humic-type" material). Samples collected from the Marne basin are characterized by a third specific type of organic matter. For samples collected in November 2011 and September 2012 the distributions observed for the 7 components determined by PARAFAC treatment were different for each studied basins, highlighting different organic materials in each zone. A homogeneous distribution of the components was obtained for the samples collected during the flood in February 2013.

Thanh Nguyen, Phuong; Guo, Yuzhe; Bonnot, Caroline; Varrault, Gilles; Benedetti, Marc; Parlanti, Edith

2014-05-01

289

Study on the binding interaction of chromium(VI) with humic acid using UV-vis, fluorescence spectroscopy and molecular modeling  

NASA Astrophysics Data System (ADS)

In this report, the binding interaction of chromium(VI), as Cr2O72-, with humic acid was studied by using UV-visible absorption, fluorescence spectroscopy, and molecular modeling method. The fluorescence spectral data indicated that the binding interaction existed between Cr2O72- and humic acid and the order of magnitude of binding constants were 103. The rise in temperature caused a decrease in the values of the binding constant of humic acid with Cr2O72-. Thermodynamic analysis presented that multi-intermolecular forces including hydrogen bonding, hydrophobic, and electrostatic forces were involved in the binding process at pH 6.5. The spectral data also indicated that Cr2O72- affected the aromatic ring structures in humic acid. Furthermore, the molecular modeling analysis indicated that a lot of reactive groups and binding cavities in HA played a key role in its binding with Cr2O72-.

Gu, Yun-Lan; Yin, Ming-Xing; Zhang, Hong-Mei; Wang, Yan-Qing; Shi, Jing-hua

2015-02-01

290

Spectroscopy and chemistry of the atmosphere of Uranus  

NASA Technical Reports Server (NTRS)

A comprehensive review of the chemistry and spectroscopy of the Uranian atmosphere is presented by means of earth-based, earth-orbital, and Voyager 2 observations covering the UV, visible, infrared, and radio wavelength regions. It is inferred from these observations, in concert with the average density of about 1.3 g/cu cm, that the Uranian atmosphere is enriched in heavy elements relative to solar composition. Pre-Voyager earth-based observations of CH4 bands in the visible region and Voyager radio occultation data imply a CH4/H2 volume mixing ratio of about 2 percent corresponding to an enrichment of approximately 24 times the solar value of 0.000835. In contrast to CH4, microwave observations indicate an apparent depletion of NH3 in the 155-to-200-K region of the atmosphere by 100 to 200 times relative to the solar NH3/H2 mixing ratio of -0.000174. It is suggested that the temporal and latitudinal variations deduced for the NH3/H2 mixing ratio in this region of the Uranian atmosphere are due to atmospheric circulation effects.

Fegley, Bruce, Jr.; Gautier, Daniel; Owen, Tobias; Prinn, Ronald G.

1991-01-01

291

Ultraviolet Spectroscopy of Asteroid(4) Vesta  

NASA Technical Reports Server (NTRS)

We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm arc derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope in the ultraviolet displays a sharp minimum ncar sub-Earth longitude of 20deg, and maximum in the eastern hemisphere. This is completely consistent with the distribution of the spectral slope in the visible wavelength. The uncertainty of the measurement in the ultraviolet is approx.20%, and in the visible wavelengths better than 10%. The amplitude of Vesta's rotational lightcurves is approx.10% throughout the range of wavelengths we observed, but is smaller at 950 nm (approx.6%) ncar the 1-micron mafic band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/ncar-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible. and ncar-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies lack of global space weathering on Vesta. Keyword,: Asteroid Vesta; Spectrophotometry; Spectroscopy; Ultraviolet observations; Hubble Space Telescope observations

Li, Jian-Yang; Bodewits, Dennis; Feaga, Lori M.; Landsman, Wayne; A'Hearn, Michael F.; Mutchler, Max J.; Russell, Christopher T.; McFadden, Lucy A.; Raymond, Carol A.

2011-01-01

292

Direct and quantitative absorptive spectroscopy of nanowires  

E-print Network

Photonic nanostructures exhibit unique optical properties that are attractive in many different applications. However, measuring the optical properties of individual nanostructures, in particular the absorptive properties, ...

Tong, Jonathan Kien-Kwok

2012-01-01

293

Quantitative spectroscopy for detection of cervical dysplasia  

E-print Network

The current clinical standard for cervical cancer diagnosis is colposcopy, a procedure that involves visual inspection and biopsy of at-risk tissue, followed by histopathology. The major objective of colposcopy is detection ...

Mirkovi?, Jelena, Ph. D. Massachusetts Institute of Technology

2009-01-01

294

Journal of Quantitative Spectroscopy & Radiative Transfer ] (  

E-print Network

, ammonium nitrate, sulfuric acid and nitric acid over a range of compositions and temperatures; Ammonium sulfate; Ammonium nitrate; Sulfuric acid; Nitric acid; Infrared remote sensing 1. Introduction

295

* Corresponding author. Journal of Quantitative Spectroscopy &  

E-print Network

Abstract An analytical variation of the discrete-ordinates method is used to establish a concise: Rare"ed gas dynamics; Discrete ordinates 1. Introduction The problem of heat conduction in a slightly-analytical, numerical approach, based on an analytical version of the discrete-ordinates method [11}14] and some new

Siewert, Charles E.

296

Quantitative Thinking.  

ERIC Educational Resources Information Center

An appeal for more research to determine how to educate children as effectively as possible is made. Mathematics teachers can readily examine the educational problems of today in their classrooms since learning progress in mathematics can easily be measured and evaluated. Since mathematics teachers have learned to think in quantitative terms and…

DuBridge, Lee A.

297

Spectroscopy: Nanoscale terahertz spectroscopy  

NASA Astrophysics Data System (ADS)

The advent of terahertz spectroscopy schemes that offer single-photon sensitivity, femtosecond time resolution and nanometre spatial resolution is creating new opportunities for investigating ultrafast charge dynamics in semiconductor structures.

Shigekawa, Hidemi; Yoshida, Shoji; Takeuchi, Osamu

2014-11-01

298

TWO-COLOR FLUORESCENCE (CROSS-)CORRELATION SPECTROSCOPY ON A SELECTIVE PLANE ILLUMINATION MICROSCOPE  

E-print Network

TWO-COLOR FLUORESCENCE (CROSS-)CORRELATION SPECTROSCOPY ON A SELECTIVE PLANE ILLUMINATION: Imaging fluorescence cross-correlation spectroscopy, selective plane illumination microscopy, quantitative imaging, EMCCD camera ABSTRACT: Fluorescence correlation spectroscopy (FCS) is a useful technology

Garbe, Christoph S.

299

Sensitively monitoring photodegradation process of organic dye molecules by surface-enhanced Raman spectroscopy based on Fe3O4@SiO2@TiO2@Ag particle.  

PubMed

Photodegradation of organic dye molecules has attracted extensive attention because of their high toxicity to water resources. Compared with traditional UV-visible spectroscopy, SERS technology can reflect more sensitively the catalytic degradation process occurring on the surface of the catalysts. In this paper, we report the synthesis and structure of Fe3O4@SiO2@TiO2@Ag composite, which integrates SERS active Ag nanostructure with catalytically active titania. The degradation of the typical dye molecule crystal violet (CV), as an example, is investigated in the presence of the as-prepared Fe3O4@SiO2@TiO2@Ag composite structure, which exhibits high catalytic activity and good SERS performance. At the same time, renewable photocatalytic activity was also investigated. PMID:25192200

Qin, Suhua; Cai, Wenya; Tang, Xianghu; Yang, Liangbao

2014-11-01

300

High-pressure-low-temperature cryostat designed for use with fourier transform infrared spectrometers and time-resolved infrared spectroscopy.  

PubMed

The design for a new high-pressure-low-temperature infrared (IR) cell for performing experiments using conventional Fourier transform infrared or fast laser-based time-resolved infrared spectroscopy, in a range of solvents, is described. The design builds upon a commercially available compressor and cold end (Polycold PCC(®) and CryoTiger(®)), which enables almost vibration-free operation, ideal for use with sensitive instrumentation. The design of our cell and cryostat allows for the study of systems at temperatures from 77 to 310 K and at pressures up to 250 bar. The CaF2 windows pass light from the mid-IR to the ultraviolet (UV), enabling a number of experiments to be performed, such as Raman, UV-visible absorption spectroscopy, and time-resolved techniques where sample excitation/probing using continuous wave or pulsed lasers is required. We demonstrate the capabilities of this cell by detailing two different applications: (i) the reactivity of a range of Group V-VII organometallic alkane complexes using time-resolved spectroscopy on the millisecond timescale and (ii) the gas-to-liquid phase transition of CO2 at low temperature, which is applicable to measurements associated with transportation issues related to carbon capture and storage. PMID:24666949

Calladine, James A; Love, Ashley; Fields, Peter A; Wilson, Richard G M; George, Michael W

2014-01-01

301

Raman spectroscopy for noninvasive glucose measurements  

E-print Network

We report the first successful study of the use of Raman spectroscopy for quantitative, noninvasive (“transcutaneous”) measurement of blood analytes, using glucose as an example. As an initial evaluation of the ability of ...

Enejder, Annika M. K.

302

Early detection of high-grade squamous intraepithelial lesions in the cervix with quantitative spectroscopic imaging  

E-print Network

Quantitative spectroscopy has recently been extended from a contact-probe to wide-area spectroscopic imaging to enable mapping of optical properties across a wide area of tissue. We train quantitative spectroscopic imaging ...

Lau, Condon

303

Quarkonium spectroscopy  

SciTech Connect

Recent experimental investigations of heavy quark-antiquark bound state systems are reviewed. Results from SPEAR on charmonium spectroscopy and from DORIS and CESR on bottomonium spectroscopy are presented. The current status of the search for top is also discussed.

Scharre, D.L.

1981-06-01

304

Experimental validation of Monte Carlo modeling of fluorescence in tissues in the UV-visible spectrum  

Microsoft Academic Search

The goal of the work is to experimentally verify Monte Carlo modeling of fluorescence and diffuse reflectance measurements in turbid, tissue phantom models. In particular, two series of simula- tions and experiments, in which one optical parameter (absorption or scattering coefficient) is varied while the other is fixed, are carried out to assess the effect of the absorption coefficient (m

Quan Liu; Changfang Zhu; Nirmala Ramanujam

2003-01-01

305

Signatures in vibrational and UV-visible absorption spectra for identifying cyclic hydrocarbons by graphene fragments  

NASA Astrophysics Data System (ADS)

To promote possible applications of graphene in molecular identification based on stacking effects, in particular in recognizing aromatic amino acids and even sequencing nucleobases in life sciences, we comprehensively study the interaction between graphene segments and different cyclic organic hydrocarbons including benzene (C6H6), cyclohexane (C6H12), benzyne (C6H4), cyclohexene (C6H10), 1,3-cyclohexadiene (C6H8(1)) and 1,4-cyclohexadiene (C6H8(2)), using the density-functional tight-binding (DFTB) method. Interestingly, we find obviously different characteristics in Raman vibrational and ultraviolet visible absorption spectra of the small molecules adsorbed on the graphene sheet. Specifically, we find that both spectra involve clearly different characteristic peaks, belonging to the different small molecules upon adsorption, with the ones of ionized molecules being more substantial. Further analysis shows that the adsorptions are almost all due to the presence of dispersion energy in neutral cases and involve charge transfer from the graphene to the small molecules. In contrast, the main binding force in the ionic adsorption systems is the electronic interaction. The results present clear signatures that can be used to recognize different kinds of aromatic hydrocarbon rings on graphene sheets. We expect that our findings will be helpful for designing molecular recognition devices using graphene.To promote possible applications of graphene in molecular identification based on stacking effects, in particular in recognizing aromatic amino acids and even sequencing nucleobases in life sciences, we comprehensively study the interaction between graphene segments and different cyclic organic hydrocarbons including benzene (C6H6), cyclohexane (C6H12), benzyne (C6H4), cyclohexene (C6H10), 1,3-cyclohexadiene (C6H8(1)) and 1,4-cyclohexadiene (C6H8(2)), using the density-functional tight-binding (DFTB) method. Interestingly, we find obviously different characteristics in Raman vibrational and ultraviolet visible absorption spectra of the small molecules adsorbed on the graphene sheet. Specifically, we find that both spectra involve clearly different characteristic peaks, belonging to the different small molecules upon adsorption, with the ones of ionized molecules being more substantial. Further analysis shows that the adsorptions are almost all due to the presence of dispersion energy in neutral cases and involve charge transfer from the graphene to the small molecules. In contrast, the main binding force in the ionic adsorption systems is the electronic interaction. The results present clear signatures that can be used to recognize different kinds of aromatic hydrocarbon rings on graphene sheets. We expect that our findings will be helpful for designing molecular recognition devices using graphene. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02933f

Meng, Yan; Wu, Qi; Chen, Lei; Wangmo, Sonam; Gao, Yang; Wang, Zhigang; Zhang, Rui-Qin; Ding, Dajun; Niehaus, Thomas A.; Frauenheim, Thomas

2013-11-01

306

SO2 frost - UV-visible reflectivity and Io surface coverage  

NASA Technical Reports Server (NTRS)

The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

Nash, D. B.; Fanale, F. P.; Nelson, R. M.

1980-01-01

307

Characterization of tannin-metal complexes by UV-visible spectrophotometry  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tannins enter soils by plant decay and rain throughfall, but little is known of their effects on soils. Tannins may influence bioavailability and toxicity of metals by forming complexes and by mediating redox reactions. We evaluated the affinity and stoichiometry of Al(III) for a gallotannin, pent...

308

Effect of Surface Reflectivity Variations On Uv-visible Limb Scattering Measurements of The Atmosphere  

Microsoft Academic Search

Solar UV and visible radiation scattered at the limb of the Earth's atmosphere is used for measuring density profiles of atmosperic trace gases. For example, the OSIRIS instrument on Odin and SCIAMACHY on Envisat use this technique. A limb-viewing instrument does not see Earth's surface or tropospheric clouds directly. However, in- direct light reflected from the surface or low altitude

L. Oikarinen

2002-01-01

309

Synthesis, FTIR, FT-Raman, UV–visible, ab initio and DFT studies on benzohydrazide  

Microsoft Academic Search

A systematic vibrational spectroscopic assignment and analysis of benzohydrazide (BH) has been carried out by using FTIR and FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations –ab initio (RHF) and hybrid density functional methods (B3LYP and B3PW91) performed with 6-31G(d,p) and 6-311++G(d,p) basis sets. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios

V. Arjunan; T. Rani; C. V. Mythili; S. Mohan

2011-01-01

310

Teledyne Imaging Sensors: silicon CMOS imaging technologies for x-ray, UV, visible, and near infrared  

Microsoft Academic Search

Teledyne Imaging Sensors develops and produces high performance silicon-based CMOS image sensors, with associated electronics and packaging for astronomy and civil space. Teledyne's silicon detector sensors use two technologies: monolithic CMOS, and silicon PIN hybrid CMOS. Teledyne's monolithic CMOS sensors are large (up to 59 million pixels), low noise (2.8 e- readout noise demonstrated, 1-2 e- noise in development), low

Yibin Bai; Jagmohan Bajaj; James W. Beletic; Mark C. Farris; Atul Joshi; Stefan Lauxtermann; Anders Petersen; George Williams

2008-01-01

311

Thermal decomposition and flammability of fire-resistant, UV/visible-sensitive polyarylates, copolymers and blends  

E-print Network

-polyarylate is an extremely fire-resistant thermoplastic that can be used as an efficient flame-retardant agent to be blended With the increasing stringent requirements on the fire safety of materials, searching for new heat- and flame resistance to ignition and flame spreading without additives [6]. A high-temperature wholly aromatic poly

312

UV, VISIBLE AND NIR SPECTRAL ANALYSIS OF EGGSHELLS IN THE CHARADRIIDAE FAMILY OF BIRDS  

EPA Science Inventory

We employed reflectance spectrophotometry to quantify color and mineral composition of eggshells from several species of the bird family Charadriidae to characterize species physiology and to distinguish nesting habitat preferences. We used a Shimadzu spectrophotometer to measur...

313

An Improved Flame Test for Qualitative Analysis Using a Multichannel UV-Visible Spectrophotometer  

ERIC Educational Resources Information Center

Qualitative analysis schemes are used in undergraduate laboratory settings as a way to introduce equilibrium concepts and logical thinking. The main component of all qualitative analysis schemes is a flame test, as the color of light emitted from certain elements is distinctive and a flame photometer or spectrophotometer in each laboratory is…

Blitz, Jonathan P.; Sheeran, Daniel J.; Becker, Thomas L.

2006-01-01

314

UV-Visible First-Derivative Spectrophotometry Applied to an Analysis of a Vitamin Mixture  

NASA Astrophysics Data System (ADS)

A simple new experiment that uses UV-vis spectrophotometry to introduce undergraduate chemistry students to multicomponent analysis is presented and a method for the simultaneous determination of three vitamins using derivative spectrophotometry (zero-crossing method) is described. The methodology is simple and easy to apply and allows the determination of folic acid, pyridoxine, and thiamine over the concentration ranges 1.02-14.28, 1.00-16.00, and 6.00-20.00 mg mL-1, respectively. The resulting errors were nearly always less than 5%.

Aberásturi, F.; Jiménez, A. I.; Jiménez, F.; Arias, J. J.

2001-06-01

315

Automated ground-based star-pointing UV -visible spectrometer for stratospheric measurements.  

PubMed

A novel automated ground-based star-pointing spectrometer system has been constructed for long-term deployment in Antarctica. Similar to our earlier stellar system, a two-dimensional detector array measures the spectra of the star and the adjacent sky, so that auroral emission from the sky can be subtracted from the stellar signal. Some new features are an altitude -azimuth pointing mirror, so that the spectrometer does not move; slip rings to provide its power thereby avoiding flexing of cables and restriction of all-around viewing; and a glazed enclosure around the mirror to ensure protection from rain and snow, made from flat plates to avoid changing the focal length of the telescope. The optical system can also view sunlight scattered from the zenith sky. The system automatically points and tracks selected stars and switches to other views on command. The system is now installed at Halley in Antarctica, and some preliminary measurements of ozone from Antarctica are shown. PMID:18259452

Roscoe, H K; Taylor, W H; Evans, J D; Tait, A M; Freshwater, R; Fish, D; Strong, E K; Jones, R L

1997-08-20

316

UV/visible and IR absorption cross sections of BrONO2  

NASA Astrophysics Data System (ADS)

The absorption cross sections of BrONO2 between 200 and 500 nm were measured over the temperature range 298 to 220 K using a diode array spectrometer. The BrONO2 absorption cross sections are weakly dependent on temperature at wavelengths < 450 nm (less than 10% change between 298 and 220 K) but decrease rapidly with decreasing temperature at wavelengths > 450 nm; at 480 nm the cross section decreased by ˜35% in going from 298 K to 220 K. Our room temperature absorption cross sections are in good agreement with the measurements of Spencer and Rowland (1978) over the common wavelength range of the measurements, 200 to 390 nm. We show that wavelengths longer than 390 nm must be included in the calculation of the BrONO2 atmospheric photolysis rate. We also show that photolysis of BrONO2 could be a significant atmospheric loss process for odd oxygen (due to halogen chemistry) below about 25 km. The infrared absorption cross sections for the BrONO2 band centered at 803.3 cm-1 were also measured. The integrated band strength was (2.7±0.5) × 10-17 cm2 molecule-1 cm-1.

Burkholder, James B.; Ravishankara, A. R.; Solomon, Susan

1995-08-01

317

The Hubble Space Telescope: UV, Visible, and Near-Infrared Pursuits  

NASA Technical Reports Server (NTRS)

The Hubble Space Telescope continues to push the limits on world-class astrophysics. Cameras including the Advanced Camera for Surveys and the new panchromatic Wide Field Camera 3 which was installed nu last year's successful servicing mission S2N4,o{fer imaging from near-infrared through ultraviolet wavelengths. Spectroscopic studies of sources from black holes to exoplanet atmospheres are making great advances through the versatile use of STIS, the Space Telescope Imaging Spectrograph. The new Cosmic Origins Spectrograph, also installed last year, is the most sensitive UV spectrograph to fly io space and is uniquely suited to address particular scientific questions on galaxy halos, the intergalactic medium, and the cosmic web. With these outstanding capabilities on HST come complex needs for laboratory astrophysics support including atomic and line identification data. I will provide an overview of Hubble's current capabilities and the scientific programs and goals that particularly benefit from the studies of laboratory astrophysics.

Wiseman, Jennifer

2010-01-01

318

A fast UV/visible pyrometer for shock temperature measurements to 20 000 K  

SciTech Connect

An ultraviolet/visible pyrometer is described which can measure shock temperatures from 3000 to 20 000 K. The system is modular, and in general consists of six photomultiplier tubes and two linear intensified diode array/spectrograph systems which can cover the range from 250 to 800 nm. Extension of the pyrometer's capabilities into the ultraviolet is necessary for accurate measurements above 8000 K. The nature of the shock environment requires the photomultiplier tubes to have rise times on the order of 2 ns, with a typical experiment lasting between 20 and 500 ns. The system measures absolute intensity, and is calibrated against a known tungsten lamp prior to each experiment. The highest temperature measured was 18 300 K for fluid Xe. The targets needed to contain this type of cryogenic sample are described as well.

Radousky, H.B.; Mitchell, A.C. (Lawrence Livermore National Laboratory, Livermore, California 94550 (US))

1989-12-01

319

UV-visible absorption spectra of metallic clusters from TDDFT calculations  

NASA Astrophysics Data System (ADS)

Absorption spectra of both pure silver or nickel clusters (Ag n ,n = 6-55, Ni p ,p = 8-12) and mixed silver-nickel clusters (Ag n Ni n ,n = 3-6) are investigated in the framework of the time-dependent density functional theory (TDDFT) with the use of the functional CAM-B3LYP. The spectra of silver nickel clusters are compared to those of pure silver and nickel clusters. An interpretation of spectroscopic patterns in terms of contribution from s- and d-type excitations is presented. In particular the d electrons of nickel atoms are found to play a crucial role in the optical transitions in Ni-rich systems.

Rabilloud, Franck

2013-01-01

320

Spectroscopies -- Theory  

NASA Astrophysics Data System (ADS)

This chapter explains how various spectroscopies can be used for probing the many-body quantum state of ultracold gas systems. It starts with a brief reminder of the basic theory of field-matter interactions. The general theory of linear response in the context of many-body quantum physics is then presented. A detailed theoretical description of RF spectroscopy, both the usual one and the momentum-resolved version, is given. This description applies to Raman spectroscopy as well. The basic theory behind Bragg spectroscopy and lattice modulation spectroscopy is also discussed. I explain how RF spectroscopy relates to the spectral function and how Bragg spectroscopy relates to the dynamical/static structure factor. The derivations are detailed and Green's functions are not used, so it is possible to follow this chapter based on simply knowing the basics of second quantization. Finally, self-consistent linear response theory and the use of sum rules is discussed in an overall manner.

Törmä, Päivi

2015-09-01

321

Quantitative Languages KRISHNENDU CHATTERJEE  

E-print Network

Quantitative Languages KRISHNENDU CHATTERJEE IST Austria (Institute of Science and Technology of Science and Technology Austria) and EPFL, Switzerland Quantitative generalizations of classical languages) to define several natural classes of quantitative languages over finite and infinite words; in particular

Doyen, Laurent

322

Raman spectroscopy of organic dyes adsorbed on pulsed laser deposited silver thin films  

NASA Astrophysics Data System (ADS)

The results of a surface-enhanced Raman scattering (SERS) study performed on representative organic and inorganic dyes adsorbed on silver nanostructured thin films are presented and discussed. Silver thin films were deposited on glass slides by focusing the beam from a KrF excimer laser (wavelength 248 nm, pulse duration 25 ns) on a silver target and performing the deposition in a controlled Ar atmosphere. Clear Raman spectra were acquired for dyes such as carmine lake, garanza lake and brazilwood overcoming their fluorescence and weak Raman scattering drawbacks. UV-visible absorption spectroscopy measurements were not able to discriminate among the different chromophores usually referred as carmine lake (carminic, kermesic and laccaic acid), as brazilwood (brazilin and brazilein) and as garanza lake (alizarin and purpurin). SERS measurements showed that the analyzed samples are composed of a mixture of different chromophores: brazilin and brazilein in brazilwood, kermesic and carminic acid in carmine lake, alizarin and purpurin in garanza lake. Detection at concentration level as low as 10-7 M in aqueous solutions was achieved. Higher Raman intensities were observed using the excitation line of 632.8 nm wavelength with respect to the 785 nm, probably due to a pre-resonant effect with the molecular electronic transitions of the dyes.

Fazio, E.; Neri, F.; Valenti, A.; Ossi, P. M.; Trusso, S.; Ponterio, R. C.

2013-08-01

323

Monitoring the in-situ oxide growth on uranium by ultraviolet-visible reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

We demonstrate the in-situ monitoring of oxide growth on U-0.1 wt. % Cr by means of UV-visible reflectance spectroscopy in the thickness range of ˜20-150 nm. Two different approaches are presented: In the "modeling approach," we employ a model for a metallic substrate covered by a dielectric layer, while taking into account the buildup of oxygen gradient and surface roughness. Then, we fit the simulated spectra to the experimental one. In the "extrema analysis," we derive an approximated analytical expression, which relates the oxide thickness to the position of the extrema in the reflectance spectra based on the condition for optical interference of the reflected light. Good agreement is found between the values extracted by the two procedures. Activation energy of ˜21 kcal/mole was obtained by monitoring the oxide growth in the temperature range of 22-90 °C. The upper bound for the thickness determination is argued to be mostly dictated by cracking and detachment processes in the formed oxide.

Schweke, Danielle; Maimon, Chen; Chernia, Zelig; Livneh, Tsachi

2012-11-01

324

Time-resolved magnetic circular dichroism spectroscopy of photolyzed carbonmonoxy cytochrome c oxidase (cytochrome aa3).  

PubMed Central

Nanosecond time-resolved magnetic circular dichroism (TRMCD) and time-resolved natural circular dichroism (TRCD) measurements of photolysis products of the CO complex of eukaryotic cytochrome c oxidase (CcO-CO) are presented. TRMCD spectra obtained at 100 ns and 10 microseconds after photolysis are diagnostic of pentacoordinate cytochrome a3Fe2+, as would be expected for simple photodissociation. Other time-resolved spectroscopies (UV-visible and resonance Raman), however, show evidence for unusual Fea3(2+) coordination after CO photolysis (Woodruff, W. H., O. Einarsdóttir, R. B. Dyer, K. A. Bagley, G. Palmer, S. J. Atherton, R. A. Goldbeck, T. D. Dawes, and D. S. Kliger. 1991. Proc. Nat. Acad. Sci. U.S.A. 88:2588-2592). Furthermore, time-resolved IR experiments have shown that photodissociated CO binds to CuB+ prior to recombining with Fea3(2+) (Dyer, R. B., O. Einarsdóttir, P. M. Killough, J. J. López-Garriga, and W. H. Woodruff. 1989. J. Am. Chem. Soc. 111:7657-7659). A model of the CcO-CO photolysis cycle which is consistent with all of the spectroscopic results is presented. A novel feature of this model is the coordination of a ligand endogenous to the protein to the Fe axial site vacated by the photolyzed CO and the simultaneous breaking of the Fe-imidazole(histidine) bond. PMID:1653049

Goldbeck, R A; Dawes, T D; Einarsdóttir, O; Woodruff, W H; Kliger, D S

1991-01-01

325

XPS, UV-vis spectroscopy and AFM studies on removal mechanisms of Si-face SiC wafer chemical mechanical polishing (CMP)  

NASA Astrophysics Data System (ADS)

Chemical mechanical polishing (CMP) removal mechanisms of on-axis Si-face SiC wafer have been investigated through X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) spectroscopy and atomic force microscopy (AFM). XPS results indicate that silicon oxide is formed on Si-face surface polished by the slurry including oxidant H2O2, but not that after immersing in H2O2 solution. UV-vis spectroscopy curves prove that •OH hydroxyl radical could be generated only under CMP polishing by the slurry including H2O2 and abrasive, so as to promote oxidation of Si-face to realize the effective removal; meanwhile, alkali KOH during CMP could induce the production of more radicals to improve the removal. On the other side, ultra-smooth polished surface with atomic step structure morphology and extremely low Ra of about 0.06 nm (through AFM) is obtained using the developed slurry with silica nanoparticle abrasive. Through investigating the variations of the atomic step morphology on the surface polished by different slurries, it's reveals that CMP removal mechanism involves a simultaneous process of surface chemical reaction and nanoparticle atomic scale abrasion.

Zhou, Yan; Pan, Guoshun; Shi, Xiaolei; Xu, Li; Zou, Chunli; Gong, Hua; Luo, Guihai

2014-10-01

326

Raman Spectroscopy.  

ERIC Educational Resources Information Center

Reviews literature on Raman spectroscopy from late 1981 to late 1983. Topic areas include: instrumentation and sampling; liquids and solutions; gases and matrix isolation; biological molecules; polymers; high-temperature and high-pressure studies; Raman microscopy; thin films and surfaces; resonance-enhanced and surface-enhanced spectroscopy; and…

Gerrard, Donald L.

1984-01-01

327

An examination of kernite (Na2B4O6(OH)2·3H2O) using X-ray and electron spectroscopies: quantitative microanalysis of a hydrated low-Z mineral.  

PubMed

Mineral borates, the primary industrial source of boron, are found in a large variety of compositions. One such source, kernite (Na2B4O6(OH)2·3H2O), offers an array of challenges for traditional electron-probe microanalysis (EPMA)-it is hygroscopic, an electrical insulator, composed entirely of light elements, and sensitive to both low pressures and the electron beam. However, the approximate stoichiometric composition of kernite can be analyzed with careful preparation, proper selection of reference materials, and attention to the details of quantification procedures, including correction for the time dependency of the sodium X-ray signal. Moreover, a reasonable estimation of the mineral's water content can also be made by comparing the measured oxygen to the calculated stoichiometric oxygen content. X-ray diffraction, variable-pressure electron imaging, and visual inspection elucidate the structural consequences of high vacuum treatment of kernite, while Auger electron spectroscopy and X-ray photoelectron spectroscopy confirm electron beam-driven migration of sodium and oxygen out of the near-surface region (sampling depth ? 2 nm). These surface effects are insufficiently large to significantly affect the EPMA results (sampling depth ? 400 nm at 5 keV). PMID:21892991

Meier, Douglas C; Davis, Jeffrey M; Vicenzi, Edward P

2011-10-01

328

Fast and environmentally friendly quantitative analysis of active agents in anti-diabetic tablets by an alternative laser-induced breakdown spectroscopy (LIBS) method and comparison to a validated reversed-phase high-performance liquid chromatography (RP-HPLC) method.  

PubMed

Laser-induced breakdown spectroscopy (LIBS) is evaluated as a potential analytic technique for rapid screening and quality control of anti-diabetic tablets. This paper proposes a simple LIBS-based method for the quantitative analysis of two active pharmaceutical ingredients (APIs): metformin (Met) and glybenclamide (Gly). In order to quantify both APIs, chlorine (Cl) concentration was estimated by employing the Cl/Br optical emission ratio, where Br was introduced as internal standard. Calibration curves were prepared, achieving linearity higher than 99%. On the other hand, for comparison to the proposed method, an isocratic reversed-phase high-performance liquid chromatography (RP-HPLC) method was also developed for quantitative determination of the same analytes by ultraviolet (UV) detection. The chromatographic separation was achieved on a Phenomenex Hypersil C18, 250 mm × 4.6 mm, 5 ?m column. The mobile phase was K(2)HPO(4)/H(3)PO(4)-CH(3)OH and flow rate was 1.0 mL min(-1). The method is linear over a range of 10-60 ?g mL(-1) for Gly and 5-30 ?g mL(-1) for Met and the correlation coefficients were ?0.99. Recoveries were found to be in the range of 95-101%. Furthermore, four different commercial brands of each active agent were evaluated by both proposed LIBS and chromatographic methods and results were compared with each other. The comparison was satisfactorily validated by analysis of variance (ANOVA). PMID:23146185

Contreras, Victor Ulises; Meneses-Nava, Marco A; Ornelas-Soto, Nancy; Barbosa-García, Oracio; López-de-Alba, Pedro L; Maldonado, José L; Ramos-Ortiz, Gabriel; Acevedo-Aguilar, Francisco J; López-Martínez, Leticia

2012-11-01

329

Quantitative Mineralogical Characterization of Oregon Erionite  

NASA Astrophysics Data System (ADS)

Erionite has been classified as Group-I Human Carcinogen by the IARC Working Group. Fibrogenetic potential of erionite varies from low to high yield of mesothelioma. This may require quantitative characterization of physicochemical properties of erionite before any experimental design. The toxicity of the mineral is such that quantitative characterization of erionite is extremely important. Yet, often the erionite specimens were incompletely or incorrectly characterized throwing doubt on the results of the work. For example, none of the Turkish erionite published until recently had balance error (E%) less than 10%, and Mg cation of the type specimen of erionite-Ca from Maze, Niigita Prefecture, Japan is more than 0.8. In the present study, erionite sample near Rome, Oregon have been quantitatively characterized using powder x-ray diffraction, Reitveld refinement, scanning electron microscopy, energy dispersive spectroscopy, inductively coupled plasma - mass spectroscopy, and Massbauer spectroscopy. The cell parameters of the erionite-K from Oregon is computed as a=13.2217(2) Å and c=15.0671 Å; chemical composition of the erionite as major oxides, rare earth elements and other trace elements, are characterized quantitatively. Crystal chemistries of the erionite are computed based upon the quidelines of the IMAA zeolite report of 1997.

Dogan, A.; Dogan, M.; Ballirano, P.

2006-12-01

330

NMR Spectroscopy  

NSDL National Science Digital Library

Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts. These questions pertain to Nuclear magnetic resonance (NMR) spectroscopy and include topics such as: Chemical Shift, Proton NMR, and Carbon NMR.

Reich, Ieva

331

IR Spectroscopy  

NSDL National Science Digital Library

These organic chemistry quiz questions from the JCE question bank focus on the topic of Infrared Spectroscopy. Students can use these as review material or to prepare for exams. Answer keys are made available to teachers for a small fee.

Reich, Ieva

332

Near-infrared Raman instrument for rapid and quantitative measurements of clinically important analytes  

E-print Network

laser Raman spectroscopy instrument to measure the concentrations of many important analytes is acquired from the sample in 10 s. The major error in quantitative Raman spectroscopy caused the Raman spectra of other mol- ecules. Although Raman spectroscopy offers the significant ad- vantage

Qu, Jianan

333

Quantitative concentration measurements of creatinine dissolved in water and urine using Raman  

E-print Network

that Raman spectroscopy with these Teflon®-AF LCOFs is stable enough for quantitative concentration Instrumentation Engineers. [DOI: 10.1117/1.1917842] Keywords: Raman; spectroscopy; LCOF; waveguide; urine; PLS for publication Oct. 29, 2004; published online May 11, 2005. 1 Introduction Raman spectroscopy is a useful method

Berger, Andrew J.

334

Anatomy-Based Algorithms for Detecting Oral Cancer Using Reflectance and Fluorescence Spectroscopy  

E-print Network

OBJECTIVES: We used reflectance and fluorescence spectroscopy to noninvasively and quantitatively distinguish benign from dysplastic/malignant oral lesions. We designed diagnostic algorithms to account for differences in ...

McGee, Sasha

335

Blood analysis by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r2 values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

Enejder, Annika M. K.; Koo, Tae-Woong; Oh, Jeankun; Hunter, Martin; Sasic, Slobodan; Feld, Michael S.; Horowitz, Gary L.

2002-11-01

336

Evanescent Spectroscopy Evanescent Spectroscopy -Theory and  

E-print Network

Evanescent Spectroscopy Evanescent Spectroscopy - Theory and Experiment Alina Karabchevsky #12;Evanescent Spectroscopy Outline 1 Introduction 2 Literature Overview 3 Photonic #12;Evanescent Spectroscopy Introduction Surface Enhanced Spectroscopy M My· B By· M MyB MyL MyE My

337

Laser-induced plasma spectroscopy: principles, methods and applications  

SciTech Connect

Principles of the Laser Induced Plasma Spectroscopy and its advances are reported. Methods for obtaining quantitative analyses are described, together with discussion of some applications and the specific problems.

Lazic, Violeta; Colao, Francesco; Fantoni, Roberta; Spizzichino, Valeria [ENEA, FIS-LAS, V. E. Fermi 45, Frascati (RM) (Italy); Jovicevic, Sonja [Institute of Physics, 11080 Belgrade, Pregrevica 118 (Serbia and Montenegro)

2006-12-01

338

Atomic Spectroscopy  

NSDL National Science Digital Library

This article outlines the main concepts of atomic structure, with some emphasis on terminology and notation. Topics of discussion include wavelengths, intensities, shapes of spectral lines, and LS coupling. Originally appearing in the Atomic, Molecular, and Optical Physics Handbook, edited by Drake, this online version of Atomic Spectroscopy contains internal links as well as external links to spectroscopic data.

Martin, William; Wiese, Wolfgang

2003-10-10

339

Mössbauer Spectroscopy  

Microsoft Academic Search

Mössbauer spectroscopy, based on the recoilless resonance emission and absorption of gamma photons observed with certain atomic nuclei, is a powerful investigating tool in most disciplines of natural science ranging from physics to chemistry to biology. This nuclear method makes it possible to measure the energy difference between nuclear energy levels to an extremely high resolution (up to 13-15 decimals).

E. Kuzmann; Z. Homonnay; S. Nagy; K. Nomura

2011-01-01

340

Fluorescence Spectroscopy  

NSDL National Science Digital Library

This resource, part of the Spectroscopy Lab Suite, simulates optical transitions in a Fluorescent light. In this illustration, the transitions between bands in the phosphor coating of the light are shown. The phosphor is excited by discharge in a mercury gas. The energy levels and transitions in the phosphor material can be changed.

Zollman, Dean

2010-05-21

341

Infrared Spectroscopy  

NSDL National Science Digital Library

This 38-page PDF document is a chapter from the Handbook of Instrumental Techniques for Analytical Chemistry. The chapter explains how infrared spectroscopy works (no comma) along with its general uses, common applications, range and limitations. Also included are spectrometer designs, information about sample preparation, analytical methods, related methods such as gas chromotography and diffuse reflectance, and costs and instrument vendors.

Hsu, C. P.; Hall, Prentice

342

Phosphorescence Spectroscopy  

NSDL National Science Digital Library

This resource, part of the Spectroscopy Lab Suite, simulates optical transitions in a phosphorescent material. In this illustration of a simple experiment, the optical absorption and emission of the material, and the thermal excitation of the bound impurity state are shown. The energy levels and transitions in the material can be changed.

Zollman, Dean

343

Treatment assessment of radiotherapy using MR functional quantitative imaging  

PubMed Central

Recent developments in magnetic resonance (MR) functional quantitative imaging have made it a potentially powerful tool to assess treatment response in radiation therapy. With its abilities to capture functional information on underlying tissue characteristics, MR functional quantitative imaging can be valuable in assessing treatment response and as such to optimize therapeutic outcome. Various MR quantitative imaging techniques, including diffusion weighted imaging, diffusion tensor imaging, MR spectroscopy and dynamic contrast enhanced imaging, have been investigated and found useful for assessment of radiotherapy. However, various aspects including data reproducibility, interpretation of biomarkers, image quality and data analysis impose challenges on applications of MR functional quantitative imaging in radiotherapy assessment. All of these challenging issues shall be addressed to help us understand whether MR functional quantitative imaging is truly beneficial and contributes to future development of radiotherapy. It is evident that individualized therapy is the future direction of patient care. MR functional quantitative imaging might serves as an indispensable tool towards this promising direction.

Chang, Zheng; Wang, Chunhao

2015-01-01

344

Qualitative and Quantitative  

E-print Network

Qualitative and Quantitative Reliability AssessmentKARAMA KANOUN, MOHAMED KAÃ?NICHE, and JEAN-CLAUDE LAPRIE French National Organization for Scientific Research Traditional system reliability efforts have

Kaâniche, Mohamed

345

Quantitative Measurements of HO2 and other products of n-butane oxidation (H2O2, H2O, CH2O, and C2H4) at elevated temperatures by direct coupling of a jet-stirred reactor with sampling nozzle and cavity ring-down spectroscopy (cw-CRDS).  

PubMed

For the first time quantitative measurements of the hydroperoxyl radical (HO2) in a jet-stirred reactor were performed thanks to a new experimental setup involving fast sampling and near-infrared cavity ring-down spectroscopy at low pressure. The experiments were performed at atmospheric pressure and over a range of temperatures (550-900 K) with n-butane, the simplest hydrocarbon fuel exhibiting cool flame oxidation chemistry which represents a key process for the auto-ignition in internal combustion engines. The same technique was also used to measure H2O2, H2O, CH2O, and C2H4 under the same conditions. This new setup brings new scientific horizons for characterizing complex reactive systems at elevated temperatures. Measuring HO2 formation from hydrocarbon oxidation is extremely important in determining the propensity of a fuel to follow chain-termination pathways from R + O2 compared to chain branching (leading to OH), helping to constrain and better validate detailed chemical kinetics models. PMID:25381864

Djehiche, Mokhtar; Le Tan, Ngoc Linh; Jain, Chaithanya D; Dayma, Guillaume; Dagaut, Philippe; Chauveau, Christian; Pillier, Laure; Tomas, Alexandre

2014-11-26

346

Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

Mössbauer spectroscopy, based on the recoilless resonance emission and absorption of ? photons observed with certain atomic nuclei, is a powerful investigating tool in most disciplines of natural science ranging from physics to chemistry to biology. This nuclear method makes it possible to measure the energy difference between nuclear energy levels to an extremely high resolution (up to 13-15 decimals). This resolution is required to measure the slight variation of nuclear energy levels caused by electric monopole, electric quadrupole, and magnetic dipole interactions between the electrons and the nucleus. Mössbauer nuclides being at different microenvironments act as local probes for the sensitive detection of the hyperfine interactions. Such interactions reflect changes in the electronic, magnetic, geometric, or defect structure as well as in the lattice vibrations, serving as a basis for a variety of applications. In this chapter, the principles and some practical aspects of Mössbauer spectroscopy are described.

Kuzmann, E.; Homonnay, Z.; Nagy, S.; Nomura, K.

347

Diffuse reflectance spectroscopy of fibrous proteins.  

PubMed

UV-visible diffuse reflectance (DR) spectra of the fibrous proteins wool and feather keratin, silk fibroin and bovine skin collagen are presented. Natural wool contains much higher levels of visible chromophores across the whole visible range (700-400 nm) than the other proteins and only those above 450 nm are effectively removed by bleaching. Both oxidative and reductive bleaching are inefficient for removing yellow chromophores (450-400 nm absorbers) from wool. The DR spectra of the four UV-absorbing amino acids tryptophan, tyrosine, cystine and phenylalanine were recorded as finely ground powders. In contrast to their UV-visible spectra in aqueous solution where tryptophan and tyrosine are the major UV absorbing species, surprisingly the disulphide chromophore of solid cystine has the strongest UV absorbance measured using the DR remission function F(R)(?). The DR spectra of unpigmented feather and wool keratin appear to be dominated by cystine absorption near 290 nm, whereas silk fibroin appears similar to tyrosine. Because cystine has a flat reflectance spectrum in the visible region from 700 to 400 nm and the powder therefore appears white, cystine absorption does not contribute to the cream colour of wool despite the high concentration of cystine residues near the cuticle surface. The disulphide absorption of solid L: -cystine in the DR spectrum at 290 nm is significantly red shifted by ~40 nm relative to its wavelength in solution, whereas homocystine and lipoic acid showed smaller red shifts of 20 nm. The large red shift observed for cystine and the large difference in intensity of absorption in its UV-visible and DR spectra may be due to differences in the dihedral angle between the crystalline solid and the solvated molecules in solution. PMID:22218994

Millington, Keith R

2012-09-01

348

Impedance spectroscopy  

Microsoft Academic Search

Impedance spectroscopy (IS) is a general term that subsumes the small-signal measurement of the linear electrical response\\u000a of a material of interest (including electrode effects) and the subsequent analysis of the response to yield useful information\\u000a about the physicochemical properties of the system. Analysis is generally carried out in the frequency domain, although measurements\\u000a are sometimes made in the time

J. Ross Macdonald

1992-01-01

349

Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

Anderson localization of matter-waves in a controlled disorder: a quantum simulator? / A. Aspect ... [et al.] -- Squeezing and entanglement in a Bose-Einstein condensate / C. Gross ... [et al.] -- New physics in dipolar Bose-Einstein condensates / Y. Kawaguchi, H. Saito, and M. Ueda -- Observation of vacuum fluctuations in a spinor Bose-Einstein condensate / C. Klempt ... [et al.] -- Negative-index media for matter waves / F. Perales ... [et al.] -- Entanglement of two individual atoms using the Rydberg blockade / A. Browaeys ... [et al.] -- Array of mesoscopic ensembles on a magnetic atom chip / A. F. Tauschinsky ... [et al.] -- Stability of the proton-to-electron mass ratio tested with molecules using an optical link to primary clock / A. Amy-Klein ... [et al.] -- Metastable helium: lifetime measurements using cold atoms as a test of QED / K. G. H. Baldwin ... [et al.] -- Optical lattice clocks with single occupancy bosons and spin-polarized fermions toward 10[symbol] accuracy / M. Takamoto ... [et al.] -- Frequency measurements of Al[symbol] and Hg[symbol] optical standards / W. M. Itano ... [et al.] -- Switching of light with light using cold atoms inside a hollow optical fiber / M. Bajcsy ... [et al.] -- Room-temperature atomic ensembles for quantum memory and magnetometry / K. Jensen ... [et al.] -- Components for multi-photon non-classical state preparation and measurement / G. Puentes ... [et al.] -- Quantum field state measurement and reconstruction in a cavity by quantum nondemolition photon counting / M. Brune ... [et al.] -- XUV frequency comb spectroscopy / C. Gohle ... [et al.] -- Ultrahigh-repetition-rate pulse train with absolute-phase control produced by an adiabatic raman process / M. Katsuragawa ... [et al.] -- Strongly correlated bosons and fermions in optical lattices / S. Will ... [et al.] -- Bragg spectroscopy of ultracold bose gases in optical lattices / L. Fallani ... [et al.] -- Synthetic quantum many-body systems / C. Guerlin ... [et al.] -- Ultracold Ytterbium atoms in optical lattices / S. Sugawa ... [et al.] -- Ultracold polar molecules in the rovibrational ground state / J. Deiglmayr ... [et al.] -- Polar molecules near quantum degeneracy / J. Ye and D. S. Jin -- Production of a quantum gas of rovibronic ground-state molecules in an optical lattice / J. G. Danzl ... [et al.] -- Recent progress in x-ray nonlinear optics / K. Tamasaku, K. Sawada, and T. Ishikawa -- Gas in scattering media absorption spectroscopy - laser spectroscopy in unconventional environments / S. Svanberg -- Laser spectroscopy on relativistic ion beams / S. Reinhardt ... [et al.] -- Single frequency microcavity lasers and applications / L. Xu ... [et al.].

Katori, H.; Yoneda, H.; Nakagawa, K.; Shimizu, F.

2010-02-01

350

Key Dynamics of Conserved Asparagine in a Cryptochrome/Photolyase Family Protein by FTIR Spectroscopy  

PubMed Central

Cryptochromes (Crys) and photolyases (Phrs) are flavoproteins that contain an identical cofactor (flavin adenine dinucleotide, FAD) within the same protein architecture, but whose physiological functions are entirely different. In this study, we investigated light-induced conformational changes of a cyanobacterium Cry/Phr-like protein (SCry-DASH) with UV–visible and Fourier transform infrared (FTIR) spectroscopy. We developed a system to measure light-induced difference spectra under the concentrated conditions. In the presence of reducing agent, SCry-DASH showed photoreduction to the reduced form, and we identified a signal unique for an anionic form in the process. Difference FTIR spectra enabled us to assign characteristic FTIR bands to the respective redox forms of FAD. An asparagine residue, which anchors the FAD embedded within the protein is conserved in not only the cyanobaterial protein, but also in Phrs and other Crys including the mammalian clock-related Crys. By characterizing an asparagine-to-cysteine (N392C) mutant of SCry-DASH, which mimics an insect specific Cry, we identified structural changes of the carbonyl group of this conserved asparagine upon light-irradiation. We also found that the N392C mutant is stabilized in the anionic form. We did not observe a signal from protonated carboxylic acid residues during the reduction process, suggesting that the carboxylic acid moiety would not be directly involved as a proton donor to FAD in the system. These results are in contrast to plant specific Crys represented by Arabidopsis thaliana Cry1 which carry Asp at the position. We discuss potential roles for this conserved asparagine position and functional diversity in the Cry/Phr frame. PMID:20828134

Iwata, Tatsuya; Zhang, Yu; Hitomi, Kenichi; Getzoff, Elizabeth D.; Kandori, Hideki

2012-01-01

351

NMR spectroscopy  

SciTech Connect

In a method of heteronuclear decoupling in high resolution pulsed NMR spectroscopy, during acquisition of signals emanating from a nuclear species to be observed (e.g. carbon-13), irradiation of an interfering nuclear species (e.g. protons) is effected by means of a train of composite pulses, each of which approximately inverts the longitudinal magnetization. The pulses are of two types respectively having opposite R.F. phases, and the train constitutes a repeated sequence which consists of 2 /SUP N/ /sup +1/ pulses of each type (where N is a positive integer) and which has a form chosen in accordance with specific rules to ensure effective decoupling.

Levitt, M.H.; Frenkiel, Th.A.

1984-09-04

352

Molecular Spectroscopy and Remote-Sensing of the Earth's Atmosphere: Progress from Laboratory Studies  

SciTech Connect

In this paper we present some recent developments in the field of molecular spectroscopy applied to the measurement of trace gases in the Earth's atmosphere, in particular concerning the spectroscopy of unstable species or radicals and of isotopic species, but also in the field of quantitative spectroscopy, in the context of more and more challenging requirements arising from modern remote-sensing experiments.

Orphal, Johannes [Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA) University of Paris-12 (Paris-Est), CNRS UMR 7583, 94010 Creteil Cedex (France)

2009-03-11

353

Experimental molecular spectroscopy in shock-compressed materials  

SciTech Connect

Shocked materials present an exciting challenge to the experimental spectroscopist. The severe constraints in time and space imposed by the shock process can also be accompanied by chemical complexity. Many standard spectroscopic techniques have recently been adapted with varying degrees of success. Those discussed here are uv/visible absorption, emission, and fluorescence, infrared absorption, and spontaneous and coherent Raman scattering. The importance of the connection to both theory and static high-pressure methods is emphasized.

Moore, D.S.; Schmidt, S.C.

1987-01-01

354

Quantitative dispersion microscopy  

PubMed Central

Refractive index dispersion is an intrinsic optical property and a useful source of contrast in biological imaging studies. In this report, we present the first dispersion phase imaging of living eukaryotic cells. We have developed quantitative dispersion microscopy based on the principle of quantitative phase microscopy. The dual-wavelength quantitative phase microscope makes phase measurements at 310 nm and 400 nm wavelengths to quantify dispersion (refractive index increment ratio) of live cells. The measured dispersion of living HeLa cells is found to be around 1.088, which agrees well with that measured directly for protein solutions using total internal reflection. This technique, together with the dry mass and morphology measurements provided by quantitative phase microscopy, could prove to be a useful tool for distinguishing different types of biomaterials and studying spatial inhomogeneities of biological samples. PMID:21113234

Fu, Dan; Choi, Wonshik; Sung, Yongjin; Yaqoob, Zahid; Dasari, Ramachandra R.; Feld, Michael

2010-01-01

355

Quantitative PCR Protocol  

NSDL National Science Digital Library

This protocol describes how to genotype mice using Quantitative Polymerase Chain Reaction (PCR). The protocol focuses specifically on Ts65Dn mice, but can be used as a basis for genotyping ohter strains.

The Jackson Laboratory (The Jackson Laboratory)

2012-01-06

356

Quantitative receptor autoradiography  

SciTech Connect

Quantitative receptor autoradiography addresses the topic of technical and scientific advances in the sphere of quantitative autoradiography. The volume opens with a overview of the field from a historical and critical perspective. Following is a detailed discussion of in vitro data obtained from a variety of neurotransmitter systems. The next section explores applications of autoradiography, and the final two chapters consider experimental models. Methodological considerations are emphasized, including the use of computers for image analysis.

Boast, C.A.; Snowhill, E.W.; Altar, C.A.

1986-01-01

357

Quantitative phase analysis of boron nitride nanotubes using Rietveld refinement  

Microsoft Academic Search

Crystalline boron nitride nanotubes (BNNTs) with an average outer diameter of about 40 nm and several micrometres in length were synthesized by chemical vapour deposition from boron and magnesium oxide. Rietveld refinement and 11B solid-state nuclear magnetic resonance (NMR) spectroscopy were employed to quantitatively determine the phase of synthesized BNNTs. The structural parameters for the BNNTs were determined by Rietveld

Yong-Il Kim; Jae Kap Jung; Kwon-Sang Ryu; Seung-Hoon Nahm; Duncan H. Gregory

2005-01-01

358

Compositional Quantitative Reasoning Krishnendu Chatterjee  

E-print Network

Compositional Quantitative Reasoning Krishnendu Chatterjee UC Berkeley Luca de Alfaro UC Santa Cruz express a wide variety of quantitative system prop- erties, such as resource consumption, price rules for compositional reasoning have quantitative counterparts in our setting. While our general

Henzinger, Thomas A.

359

Photoelectron Spectroscopy and Optical Properties of Al-Doped ZnO Films Prepared by Sputtering with Radio Frequency Power Applied to Al Target  

NASA Astrophysics Data System (ADS)

Al-doped ZnO (AZO) films were prepared on a glass substrate using a magnetron sputtering system. The metallic aluminum and ZnO targets were bombarded by radio frequency power source. The Al-dopant concentration of the films, analyzed by energy-dispersive spectroscopy, increased with increasing RF power. The electrical resistivity of the films, measured by four-point probe, revealed a decrease from 3.43 ×10-2 to 3.29 ×10-3 ? cm with increasing Al-content from 0.85 to 4.34 at. %. The crystal structure analyzed by grazing incidence X-ray diffraction indicated that all of the films prepared by sputtering with RF power preferred a stronger texture on (002) orientation than those with DC power applied to Al target. The optical transmittance, measured by UV-visible, indicated an average transmittance higher than 82% for all the films in visible region, and increased with Al-content; however, it reversed at 4.34 at. %. The band gap of the films increased from 3.39 to 3.58 eV with increasing RF power. Ultraviolet photoelectron spectroscopy (UPS) analysis revealed that a characteristic peak at approximately 5-7 eV was found in the AZO films due to the O 2p valence electrons. Meanwhile, the work functions of the undoped ZnO film and various AZO films were measured by UPS decreased from 4.9 to 4.5 eV with increasing Al-content. The chemical composition of the films was analyzed by X-ray photoelectron spectroscopy with Gaussian-resolved fitting. According to XPS analysis of O 1s for the films, we inferred that the decrease in electrical resistivity of the film with increasing Al-dopant concentration was predominated by the concentration of oxygen vacancies.

Tseng, Chun-An; Lin, Jing-Chie; Weng, Wei-Heng; Lin, Chen-Chun

2013-02-01

360

Journal of Quantitative Spectroscopy & Radiative Transfer 102 (2006) 2536  

E-print Network

of cell structure affect light scattering properties. A finite-difference-time-domain (FDTD) method microscopy measurements. An automated procedure was developed to construct a realistic three-dimensional elements of the B-cell were calculated and averaged for 30 different angles of incidence using a parallel

361

Quantitative Rapid Scan EPR Spectroscopy at 258 MHz  

PubMed Central

Experimental data obtained with an electron paramagnetic resonance (EPR) rapid scan spectrometer were translated through the reverse transfer functions of the spectrometer hardware to the sample position. Separately, theoretical calculations were performed to predict signal and noise amplitudes at the sample position for specified experimental conditions. A comparison was then made between the translated experimental values and the calculated values. Excellent agreement was obtained. PMID:20382055

Quine, Richard W.; Rinard, George A.; Eaton, Sandra S.; Eaton, Gareth R.

2011-01-01

362

Broad bandwidth frequency domain instrument for quantitative tissue optical spectroscopy  

SciTech Connect

Near-infrared (NIR) optical properties of turbid media, e.g., tissue, can be accurately quantified noninvasively using methods based on diffuse reflectance or transmittance, such as frequency domain photon migration (FDPM). Factors which govern the accuracy and sensitivity of FDPM-measured optical properties include instrument performance, the light propagation model, and fitting algorithms used to calculate optical properties from measured data. In this article, we characterize instrument, model, and fitting uncertaintics of an FDPM system designed for clinical use and investigate how each of these factors affects the quantification of NIR absorption ({mu}{sub a}) and reduced scattering ({mu}{sub s}{sup '}) parameters in tissue phantoms. The instrument is based on a 500 MHz, multiwavelength platform that sweeps through 201 discrete frequencies in as little as 675 ms. Phase and amplitude of intensity modulated light launched into tissue, i.e., diffuse photon density waves (PDW), are measured with an accuracy of {+-}0.30 degree sign and {+-}3.5%, while phase and amplitude precision are {+-}0.025 degree sign and {+-}0.20%, respectively. At this level of instrument uncertainty, simultaneous fitting of frequency-dependent phase and amplitude nonlinear model functions derived from a photon diffusion approximation provides an accurate and robust strategy for determining optical properties from FDPM data, especially for media with high absorption. In an optical property range that is characteristic of most human tissues in the NIR (5x10{sup -3}<{mu}{sub a}<5x10{sup -2} mm{sup -1}, 0.5<{mu}{sub s}{sup '}<2 mm{sup -1}), we theoretically and experimentally demonstrate that the multifrequency, simultaneous-fit approach allows {mu}{sub a} and {mu}{sub s}{sup '} to be quantified with an accuracy of {+-}5% and {+-}3%, respectively. Although exceptionally high levels of precision can be obtained using this approach (<1% of the estimated absorption and scattering values), we show that the absolute accuracy of optical property measurements is highly dependent on specific factors associated with instrument performance, model function relevance, and details of the fitting strategy used to calculate {mu}{sub a} and {mu}{sub s}{sup '}. (c) 2000 American Institute of Physics.

Pham, Tuan H. [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States)] [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Coquoz, Olivier [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States)] [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Fishkin, Joshua B. [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States)] [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Anderson, Eric [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States)] [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States); Tromberg, Bruce J. [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States)] [Beckman Laser Institute and Medical Clinic, Laser Microbeam and Medical Program, University of California at Irvine, 1002 Health Sciences Road East, Irvine, California 92612 (United States)

2000-06-01

363

Quantitative NMR spectroscopy of biologically active substances and excipients  

Microsoft Academic Search

Biologically active ingredients and excipients are the essentials of a drug formulation, such as a tablet, dragee, solution,\\u000a etc. Quality control of such substances thus plays a pivotal role in the production process of pharmaceutical drugs. Since\\u000a these agents often exhibit complex structures, consist of multiple components, or lack of a chromophore, traditional means\\u000a of characterization are often not feasible.

Tanja Beyer; Bernd Diehl; Ulrike Holzgrabe

2010-01-01

364

Quantitative Analysis of the Dentin Adhesive Interface by Auger Spectroscopy  

Microsoft Academic Search

The ultimate success of a dentin adhesive bond is dependent in large part on specific conditions at the interface between the tooth and the adhesive. Most current dentin adhesive systems use some sort of pre-treatment to demineralize the first few microns of the dentin surface, leaving a meshwork of collagen into which the adhesive resin can penetrate, infiltrate, and polymerize.

J. D. Eick; R. G. Miller; S. J. Robinson; C. Q. Bowles; P. L. Gutshall; C. C. Chappelow

1996-01-01

365

Journal of Quantitative Spectroscopy & Radiative Transfer 88 (2004) 12  

E-print Network

reported at both the ASI and the Kyiv workshop broadly available, high quality full-size papers were location, perfect weather, warm waters of the Black Sea, matchless Crimean wine, and the great enthusiasm

366

Journal of Quantitative Spectroscopy & Radiative Transfer 82 (2003) 279292  

E-print Network

pressure 16:3 Torr) and 5000­6400 cm-1 (resolution 0:040 cm-1 , nominal pressure 79 Torr) for each than 0:001 cm-1 in the 2000­5000 cm-1 spectra and 0:003 cm-1 in the 5000­6400 cm-1 spectra based 5200 5400 5600 5800 6000 6200 6400 0.0 0.5 1.0 1.5 2.0 5000 5200 5400 5600 5800 6000 6200 6400 0.0 0

Nassar, Ray

367

Journal of Quantitative Spectroscopy & Radiative Transfer 84 (2004) 493500  

E-print Network

and diagnosis, safety inspection on aircrafts and submarines, and LIDAR techniques. In this paper we develop. These investiga- tions are motivated by the potential for noninvasively assessing the optical properties

Guo, Zhixiong "James"

368

Journal of Quantitative Spectroscopy & Radiative Transfer 98 (2006) 220237  

E-print Network

). #12;ARTICLE IN PRESS Nomenclature c speed of light in vacuum ¼ 2:998 � 108 m=s g scattering anisotropy environments which involve interaction of the laser beam with scattering and absorbing particles of different multidimensional transient radiative transfer in emitting, absorbing and scattering media. The method is based

Pilon, Laurent

369

Journal of Quantitative Spectroscopy & Radiative Transfer 106 (2007) 417436  

E-print Network

scattering studies is very large because at its best all the 16 Mueller matrix ARTICLE IN PRESS www either Mie, T-matrix or cluster T-Matrix codes with suitable geometries. It is found that the relative

Draine, Bruce T.

370

Quantitative spectroscopy for the analysis of GOME data  

NASA Technical Reports Server (NTRS)

Accurate analysis of the global ozone monitoring experiment (GOME) data to obtain atmospheric constituents requires reliable, traceable spectroscopic parameters for atmospheric absorption and scattering. Results are summarized for research that includes: the re-determination of Rayleigh scattering cross sections and phase functions for the 200 nm to 1000 nm range; the analysis of solar spectra to obtain a high-resolution reference spectrum with excellent absolute vacuum wavelength calibration; Ring effect cross sections and phase functions determined directly from accurate molecular parameters of N2 and O2; O2 A band line intensities and pressure broadening coefficients; and the analysis of absolute accuracies for ultraviolet and visible absorption cross sections of O3 and other trace species measurable by GOME.

Chance, K.

1997-01-01

371

Clinical feasibility of Raman spectroscopy for quantitative blood glucose measurement  

E-print Network

Diabetes mellitus is a leading cause of morbidity and mortality worldwide, and close monitoring of blood glucose levels is crucial for its diagnosis and management. Currently, blood glucose monitoring is done by blood ...

Kong, Chae-Ryon

2011-01-01

372

Journal of Quantitative Spectroscopy & Radiative Transfer 101 (2006) 540555  

E-print Network

of as the fields scattered by the object, Esca ðr; t� and Hsca ðr; t�; where r is the position vector and t is time sums of the respective incident (original) and scattered fields: Eðr; t� ¼ Einc ðr; t� þ Esca ðr; t

373

Journal of Quantitative Spectroscopy & Radiative Transfer 98 (2006) 189201  

E-print Network

trauma patients are caused by the emergence of the secondary phase [2], which could occur within minutes and continuously monitoring system is also beneficial to patients who suffer from brain trauma. There are basically or days later after the accident. Damages in the secondary phase are due to the disorientation of body

Guo, Zhixiong "James"

374

Journal of Quantitative Spectroscopy & Radiative Transfer 105 (2007) 243263  

E-print Network

radiative transfer model based on the adding­doubling method for hyperspectral remote-sensing applications&M University, College Station, TX 77843, USA b Department of Physics, Texas A&M University, College Station, TX, 77843, USA c CIMSS/University of Wisconsin-Madison, WI, USA d Space Science and Engineering Center

Li, Jun

375

Journal of Quantitative Spectroscopy & Radiative Transfer 71 (2001) 157168  

E-print Network

galactic nuclei. Moreover, this information is needed for X-ray laser research. Our experiments use a 1-cm these objects [1] and are also important in X-ray laser research [2,3]. However, the interpretation-excitation approach to X-ray laser production [4], where the emphasis was on examination of population inversions

Cohen, David

376

CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: FOUNDATIONS FOR CALIBRATION, QUANTITATION AND SPECTROSCOPY  

EPA Science Inventory

The confocal laser-scanning microscope (CLSM) has enormous potential in many biological fields. The goal of a CLSM is to acquire and quantify fluorescence and in some instruments acquire spectral characterization of emitted signals. The accuracy of these measurements demands that...

377

CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: SPECTROSCOPY AND FOUNDATIONS FOR QUANTITATION  

EPA Science Inventory

The confocal laser-scanning microscope (CLSM) has enormous potential in many biological fields. The reliability of the CLSM to obtain specific measurements and quantify fluorescence data is dependent on using a correctly aligned machine that contains a stable laser power. For man...

378

CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: FOUNDATIONS FOR MEASUREMENTS, QUANTITATION AND SPECTROSCOPY  

EPA Science Inventory

The confocal laser-scanning microscopy (CLSM) has enormous potential in many biological fields. The goal of a CLSM is to acquire and quantify fluorescence and in some instruments acquire spectral characterization of the emitted signal. The accuracy of these measurements demands t...

379

Journal of Quantitative Spectroscopy & Radiative Transfer 92 (2005) 189200  

E-print Network

] utilized a spherical harmonics discrete-ordinates method to model radiative transfer in inhomogeneous 3D, which occupy more than 50% of the sky, are generally finite and inhomogeneous. They are the most important element in modulating the energy budget of the earth­atmosphere system ARTICLE IN PRESS www

Liou, K. N.

380

Journal of Quantitative Spectroscopy & Radiative Transfer 106 (2007) 262273  

E-print Network

of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10025, USA Abstract We use on scattering and absorption, at least in the visible part of the spectrum. Thus, the electromagnetic scattering that there are no electromagnetic interactions between the monomers. We also compute and analyze the scattering and absorption

381

Journal of Quantitative Spectroscopy & Radiative Transfer 106 (2007) 616621  

E-print Network

of electromagnetic waves by densely packed many-particle groups: Exact 3D results Michael I. Mishchenkoa,Ã?, Li Liua of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10025, USA Abstract We use the superposition T-matrix method to solve the Maxwell equations and compute electromagnetic scattering

382

Quantitative WDS analysis using electron probe microanalyzer  

SciTech Connect

In this paper, the procedure for conducting quantitative elemental analysis by ZAF correction method using wavelength dispersive X-ray spectroscopy (WDS) in an electron probe microanalyzer (EPMA) is elaborated. Analysis of a thermal barrier coating (TBC) system formed on a Ni-based single crystal superalloy is presented as an example to illustrate the analysis of samples consisting of a large number of major and minor elements. The analysis was performed by known standards and measured peak-to-background intensity ratios. The procedure for using separate set of acquisition conditions for major and minor element analysis is explained and its importance is stressed.

Ul-Hamid, Anwar [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia)]. E-mail: anwar@kfupm.edu.sa; Tawancy, Hani M. [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia); Mohammed, Abdul-Rashid I. [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia); Al-Jaroudi, Said S. [Saudi Aramco, P.O. Box 65, Tanajib 31311 (Saudi Arabia); Abbas, Nureddin M. [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia)

2006-04-15

383

Qualitative and quantitative analysis of mixtures of compounds containing both hydrogen and deuterium  

NASA Technical Reports Server (NTRS)

Method allows qualitative and quantitative analysis of mixtures of partially deuterated compounds. Nuclear magnetic resonance spectroscopy determines location and amount of deuterium in organic compounds but not fully deuterated compounds. Mass spectroscopy can detect fully deuterated species but not the location.

Crespi, H. L.; Harkness, L.; Katz, J. J.; Norman, G.; Saur, W.

1969-01-01

384

Mössbauer Spectroscopy on Compounds of Biomedical Interests  

NASA Astrophysics Data System (ADS)

Mössbauer spectroscopy (nuclear gamma resonance spectroscopy)^1 has been used in our laboratory for many biomedical applications. This presentation will demonstrate uses of Mössbauer spectroscopy to obtain qualitative and quantitative information about the electronic and magnetic properties of various systems. Information is obtained related to the electronic spin, electric quadrupole interaction, and magnetic hyperfine interactions. This technique has a very broad spectrum of applications, most of them in solid state physics and chemistry. Experiments may be done using transmission or backscattering geometry. For the past fifteen years we have successfully applied this technique to investigate materials of biomedical interest. Materials investigated include porphyrins containing europium^2, plants, over the counter medicines, hemoglobin, and ion implanted implant materials. Results of these experiments and other possible applications will be reported. 1. Leopold May, An Introduction to Mössbauer Spectroscopy, Plenum Press Z(1971). 2. Oliver, et al., Inorganica Chimica Acta, Vol. 186, 119 (1991). * Partially supported by NIH, ** Partially supported by NSF-SEM program.

Oliver, F.; Ewing, N.; Hoffman, E.; Kinyua, A.; Oladeinde, F.; Murdock, A.

2006-03-01

385

Quantitative Autonomic Testing  

PubMed Central

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be invaluable tool for evaluation of these disorders, both in clinic and research. There are number of autonomic tests, however, only few were validated clinically or are quantitative. Here, fully quantitative and clinically validated protocol for testing of autonomic functions is presented. As a bare minimum the clinical autonomic laboratory should have a tilt table, ECG monitor, continuous noninvasive blood pressure monitor, respiratory monitor and a mean for evaluation of sudomotor domain. The software for recording and evaluation of autonomic tests is critical for correct evaluation of data. The presented protocol evaluates 3 major autonomic domains: cardiovagal, adrenergic and sudomotor. The tests include deep breathing, Valsalva maneuver, head-up tilt, and quantitative sudomotor axon test (QSART). The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores (CASS). Detailed protocol is provided highlighting essential aspects of testing with emphasis on proper data acquisition, obtaining the relevant parameters and unbiased evaluation of autonomic signals. The normative data and CASS algorithm for interpretation of results are provided as well. PMID:21788940

Novak, Peter

2011-01-01

386

Quantitative glycomics strategies.  

PubMed

The correlations between protein glycosylation and many biological processes and diseases are increasing the demand for quantitative glycomics strategies enabling sensitive monitoring of changes in the abundance and structure of glycans. This is currently attained through multiple strategies employing several analytical techniques such as capillary electrophoresis, liquid chromatography, and mass spectrometry. The detection and quantification of glycans often involve labeling with ionic and/or hydrophobic reagents. This step is needed in order to enhance detection in spectroscopic and mass spectrometric measurements. Recently, labeling with stable isotopic reagents has also been presented as a very viable strategy enabling relative quantitation. The different strategies available for reliable and sensitive quantitative glycomics are herein described and discussed. PMID:23325767

Mechref, Yehia; Hu, Yunli; Desantos-Garcia, Janie L; Hussein, Ahmed; Tang, Haixu

2013-04-01

387

FT-IR, UV—visible and X-ray studies of complexes of pyridine N-oxides with pentachlorophenol  

NASA Astrophysics Data System (ADS)

The crystal structure of the 4-methoxy-2,6-dimethylpyridine N-oxide·pentachlorophenol complex has been determined by X-ray analysis. The O ··· O distance is 2.439(6) Å, the OHO angle is 152.3° and the hydrogen-bonded proton is close to the phenol molecule. The FT-IR spectra of pentachlorophenol complexes with some substituted pyridine N-oxides in the solid state and seven aprotic solvents of different polarity (? from 2.27 to 37.5) show a broad absorption. The broad absorption shows weak dependence upon solvent polarity and is classified as type (ii). UV spectra show that in the investigated complexes protons are not transferred from the phenol to the N-oxides. Formamide ( ? = 111) is a much stronger proton acceptor than the pyridine N-oxides. Pentachlorophenol in formamide is converted to the phenolate ion.

Dega-Szafran, Zofia; Grundwald-Wyspia?ska, Monika; Kania, Anna; Kosturkiewicz, Zofia; Tykarska, Ewa; Szafran, Miros?aw

1995-11-01

388

Stabilization of diketo tautomer of curcumin by premicellar anionic surfactants: UV-Visible, fluorescence, tensiometric and TD-DFT evidences  

NASA Astrophysics Data System (ADS)

A newly observed UV band of aqueous curcumin, a biologically important molecule, in presence of anionic surfactants, viz., sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and sodium dodecylsulfonate (SDSN) in buffered aqueous solutions has been studied experimentally and theoretically. The 425 nm absorption band of curcumin disappears and a new UV-band is observed at 355 nm on addition of the surfactants in the submicellar concentration range which is reversed as the surfactant concentration approaches the critical micelle concentration (CMC). The observed spectral absorption, fluorescence intensity and surface tension behavior, under optimal experimental conditions of submicellar concentration ranges of the surfactants in the pH range of 2.00-7.00, indicate that the new band is due to the ?-diketo tautomer of curcumin stabilized by interactions between curcumin and the anionic surfactants. The stabilization of the diketo tautomer by submicellar anionic surfactants described here as well as by submicellar cationic surfactant, reported recently, is unique as this is the only such behavior observed in presence of submicellar surfactants of both charge types. The experimental results are in good agreement with the theoretical calculations using ab initio density functional theory combined with time dependent density functional theory (TD-DFT) calculations.

Dutta, Anisha; Boruah, Bornali; Manna, Arun K.; Gohain, Biren; Saikia, Palash M.; Dutta, Robin K.

2013-03-01

389

FTIR, FT-Raman, UV-Visible spectra and quantum chemical calculations of allantoin molecule and its hydrogen bonded dimers  

NASA Astrophysics Data System (ADS)

FTIR, FT-Raman and electronic spectra of allantoin molecule are recorded and investigated using DFT and MP2 methods with 6-311++G(d,p) basis set. The molecular structure, anharmonic vibrational spectra, natural atomic charges, non-linear optical properties, etc. have been computed for the ground state of allantoin. The anharmonic vibrational frequencies are calculated using PT2 algorithm (Barone method) as well as VSCF and CC-VSCF methods. These methods yield results that are in remarkable agreement with the experiment. The coupling strengths between pairs of modes are also calculated using coupling integral based on 2MR-QFF approximation. The simulations on allantoin dimers have been also performed at B3LYP/6-311++G(d,p) level of theory to investigate the effect of the intermolecular interactions on the molecular structure and vibrational frequencies of the monomer. Vibrational assignments are made with the great accuracy using PED calculations and animated modes. The combination and overtone bands have been also identified in the FTIR spectrum with the help of anharmonic computations. The electronic spectra are simulated in gas and solution at TD-B3LYP/6-311++G(d,p) level of theory. The important global quantities such as electro-negativity, electronic chemical potential, electrophilicity index, chemical hardness and softness based on HOMO, LUMO energy eigenvalues are also computed. NBO analysis has been performed for monomer and dimers of allantoin at B3LYP/6-311++G(d,p) level of theory.

Alam, Mohammad Jane; Ahmad, Shabbir

2015-02-01

390

Experimental spectroscopic (FTIR, FT-Raman, FTNMR, UV–Visible) and DFT studies of 2-amino-5-chlorobenzoxazole  

Microsoft Academic Search

The solid phase FTIR and FT-Raman spectra of 2-amino-5-chlorobenzoxazole have been recorded in the regions 4000–400 and 3500–100cm?1, respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The normal coordinate analysis was carried out to confirm the precision of the assignments. The structure of the compound was optimised and the structural characteristics were determined by

V. Arjunan; P. S. Balamourougane; C. V. Mythili; S. Mohan

2011-01-01

391

Electrodeposited Ag nanoparticles on TiO2 nanorods for enhanced UV visible light photoreduction CO2 to CH4  

NASA Astrophysics Data System (ADS)

We employed the double-potentiostatic methodology to electrodeposit Ag nanoparticles on oriented single-crystalline rutile TiO2 nanorods synthesized by hydrothermal method. The synthesized composites were used as the photocatalyst to reduce CO2 to CH4 under UV irradiation, and tested by SEM, XRD, TEM, XPS, UV-vis and photoluminescence. Deposition with Ag nanoparticles was observed to enhance the photocatalytic activity (?1.5-2.64 ?mol (gcatal h)-1) up to 5 times with respect to undecorated TiO2 nanorods (?0.5 ?mol (gcatal h)-1). The increase in the CH4 yield was correlated with the surface morphology and structure of TiO2 nanorods.

Kong, Dan; Tan, Jeannie Ziang Yie; Yang, Fei; Zeng, Jieliang; Zhang, Xiwen

2013-07-01

392

FTIR, FT-Raman, UV-Visible spectra and quantum chemical calculations of allantoin molecule and its hydrogen bonded dimers.  

PubMed

FTIR, FT-Raman and electronic spectra of allantoin molecule are recorded and investigated using DFT and MP2 methods with 6-311++G(d,p) basis set. The molecular structure, anharmonic vibrational spectra, natural atomic charges, non-linear optical properties, etc. have been computed for the ground state of allantoin. The anharmonic vibrational frequencies are calculated using PT2 algorithm (Barone method) as well as VSCF and CC-VSCF methods. These methods yield results that are in remarkable agreement with the experiment. The coupling strengths between pairs of modes are also calculated using coupling integral based on 2MR-QFF approximation. The simulations on allantoin dimers have been also performed at B3LYP/6-311++G(d,p) level of theory to investigate the effect of the intermolecular interactions on the molecular structure and vibrational frequencies of the monomer. Vibrational assignments are made with the great accuracy using PED calculations and animated modes. The combination and overtone bands have been also identified in the FTIR spectrum with the help of anharmonic computations. The electronic spectra are simulated in gas and solution at TD-B3LYP/6-311++G(d,p) level of theory. The important global quantities such as electro-negativity, electronic chemical potential, electrophilicity index, chemical hardness and softness based on HOMO, LUMO energy eigenvalues are also computed. NBO analysis has been performed for monomer and dimers of allantoin at B3LYP/6-311++G(d,p) level of theory. PMID:25459622

Alam, Mohammad Jane; Ahmad, Shabbir

2015-02-01

393

Penetration of UV-visible solar radiation in the global oceans: Insights from ocean color remote sensing  

NASA Astrophysics Data System (ADS)

Penetration of solar radiation in the ocean is determined by the attenuation coefficient (Kd(?)). Following radiative transfer theory, Kd is a function of angular distribution of incident light and water's absorption and backscattering coefficients. Because these optical products are now generated routinely from satellite measurements, it is logical to evolve the empirical Kd to a semianalytical Kd that is not only spectrally flexible, but also the sun-angle effect is accounted for explicitly. Here, the semianalytical model developed in Lee et al. (2005b) is revised to account for the shift of phase function between molecular and particulate scattering from the short to long wavelengths. Further, using field data collected independently from oligotrophic ocean to coastal waters covering >99% of the Kd range for the global oceans, the semianalytically derived Kd was evaluated and found to agree with measured data within ˜7-26%. The updated processing system was applied to MODIS measurements to reveal the penetration of UVA-visible radiation in the global oceans, where an empirical procedure to correct Raman effect was also included. The results indicated that the penetration of the blue-green radiation for most oceanic waters is ˜30-40% deeper than the commonly used euphotic zone depth; and confirmed that at a depth of 50-70 m there is still ˜10% of the surface UVA radiation (at 360 nm) in most oligotrophic waters. The results suggest a necessity to modify or expand the light attenuation product from satellite ocean-color measurements in order to be more applicable for studies of ocean physics and biogeochemistry.

Lee, Zhongping; Hu, Chuanmin; Shang, Shaoling; Du, Keping; Lewis, Marlon; Arnone, Robert; Brewin, Robert

2013-09-01

394

Development of cooled UV, visible and IR windows for quasicontinuous operation of the W7-X stellarator  

NASA Astrophysics Data System (ADS)

The stellarator W7-X will be capable of running 30 min discharges. The expected continuous radiation power loads on plasma-facing optical components of 50 kW/m2 will be predominantly deposited in the form of short wavelength radiation (<60 nm) within the first millimeter of any window material. At such high heat loads actively water cooled windows are essential. The finite element-code ANSYS was used to calculate temperature and stress distributions across the windows for different window materials (CaF2, MgF2, quartz, ZnSe, sapphire), diameters, and thicknesses to explore any window design limitations resulting from the material properties of the different window substrates. First tests of a prototype water cooled window (coated with water-based colloidal graphite for effective IR absorption) in a specially designed vacuum test chamber equipped with a large surface vacuum compatible high power IR heater are being reported on. The temporal evolution of the temperature at different locations on the air side of the window and its surrounding structure is being monitored by several PT100 resistive thermometers while the spatial heat distribution across the cooled windows on their air and vacuum side is being measured with two IR cameras operating at 4 and 10 ?m.

König, R.; Ogorodnikova, O.; Hildebrandt, D.; Grosser, K.; Sehren, C. von; Baldzuhn, J.; Burhenn, R.; Mertens, Ph.; Pospieszczyk, A.; Schweer, B.; Schmidt, H.; Klinger, T.

2004-10-01

395

Critical Quantitative Inquiry in Context  

ERIC Educational Resources Information Center

This chapter briefly traces the development of the concept of critical quantitative inquiry, provides an expanded conceptualization of the tasks of critical quantitative research, offers theoretical explanation and justification for critical research using quantitative methods, and previews the work of quantitative criticalists presented in this…

Stage, Frances K.; Wells, Ryan S.

2014-01-01

396

Quantitative Population Ecology  

NSDL National Science Digital Library

Dr. Alexei Sharov of the Department of Entomology at Virginia Tech has put together this excellent teaching resource on quantitative population ecology. The online resource contains thirteen lecture handouts and eight labs, targeting beginning graduate or advanced undergraduate students; the course requires a basic understanding of statistics and ecology. Each chapter contains a concise introduction to the topic plus several more detailed subsections. The chapters are well organized and easy to navigate, and include useful color illustrations and mathematical equations. For educators and students of quantitative population ecology alike, this exceptional resource is hard to beat.

397

Baryon spectroscopy  

SciTech Connect

About 120 baryons and baryon resonances are known, from the abundant nucleon with u and d light-quark constituents up to the {Xi}{sub b}{sup -}=(bsd), which contains one quark of each generation and to the recently discovered {Omega}{sub b}{sup -}=(bss). In spite of this impressively large number of states, the underlying mechanisms leading to the excitation spectrum are not yet understood. Heavy-quark baryons suffer from a lack of known spin parities. In the light-quark sector, quark-model calculations have met with considerable success in explaining the low-mass excitations spectrum but some important aspects such as the mass degeneracy of positive-parity and negative-parity baryon excitations remain unclear. At high masses, above 1.8 GeV, quark models predict a very high density of resonances per mass interval which is not yet observed. In this review, issues are identified discriminating between different views of the resonance spectrum; prospects are discussed on how open questions in baryon spectroscopy may find answers from photoproduction and electroproduction experiments which are presently carried out in various laboratories.

Klempt, Eberhard; Richard, Jean-Marc [Helmholtz-Institut fuer Strahlen- und Kernphysik der Rheinischen Friedrich-Wilhelms Universitaet, Nussallee 14-16, D-53115 Bonn (Germany); Laboratoire de Physique Subatomique et Cosmologie, Universite Joseph Fourier-CNRS-IN2P3-INPG, Grenoble (France) and Institut de Physique Nucleaire de Lyon, Universite de Lyon, CNRS-IN2P3-Universite Claude Bernard, 4, rue Enrico Fermi, F-69622 Villeurbanne (France)

2010-04-15

398

Planetary spectroscopy  

NASA Technical Reports Server (NTRS)

The main goal of the research is charge coupled device (CCD) spectroscopic and imaging studies of the solar system in support of spacecraft investigations. Studies include the physical behavior of comets, the atmosphere of the gaseous planets, and the solid surfaces of satellites and asteroids. The major observing program consisted of approximately 50 nights of photometry of Comet Halley in order to resolve the controversy over this comet's rotation period. This data is presently being analyzed. Additional observing projects included the spectroscopic occultation of Charon by Pluto, reflection spectroscopy of Mercury, and a spectrum of the satellite Oberon. Mercury data does not corroborate the Fe(++) absorption feature reported by McCord and Clark at 8800 A but instead potentially shows a weaker feature at longer wavelengths. This position is in much closer accord with expectations for Mercury since a band center near 8800 A implies too little Fe(++) on Mercury, especially if band shifts with temperature are considered. The Pluto project proved that the deep methane absorptions visible in their combined specta are due soley to Pluto with Charon showing a flat and featureless spectrum. It appears that if Charon ever contained a substantial methane component, the satellite's low surface gravity could not hold it and the methane evaporated and escaped.

Fink, Uwe

1988-01-01

399

Amateur spectroscopy  

NASA Astrophysics Data System (ADS)

(The 1997 Presidential Address to the British Astronomical Association.) Auguste Comte is remembered for an unfortunate remark. In 1825 he said the chemical composition of stars would never be revealed. Within a decade or so the heart of the atom was being explored in remote stars through the science of spectroscopy. In simplistic terms one can regard the atom as a miniature solar system, but with the novel option that electrons (representing planets) having the ability to 'jump' from one orbit to another. In 'falling' to a lower orbit a photon of light of precise wavelength is released to travel outwards. When the electron 'jumps' to a higher orbit a photon of light is absorbed. This is taking place on a vast scale which we observe as lines in the spectrum - their position and prominence relates to the particular atomic element, temperature and pressure within the stellar atmosphere. It is beyond the scope of this Address to discuss the various processes that affect spectra, or to provide a mathematical explanation which can be found elsewhere. In any case the lack of a deep understanding does not preclude enjoyable or useful observations. Methods and results from amateurs conducting such observations are discussed in this paper.

Gavin, M. V.

1998-06-01

400

Quantitative criteria for insomnia  

Microsoft Academic Search

Formal diagnostic systems (DSM-IV, ICSD, and ICD-10) do not provide adequate quantitative criteria to diagnose insomnia. This may not present a serious problem in clinical settings where extensive interviews determine the need for clinical management. However, lack of standard criteria introduce disruptive variability into the insomnia research domain. The present study reviewed two decades of psychology clinical trials for insomnia

K. L. Lichstein; H. H. Durrence; D. J. Taylor; A. J. Bush; B. W. Riedel

2003-01-01

401

Identification of residues by infrared spectroscopy  

SciTech Connect

Mid-infrared spectroscopy of surfaces can be a very powerful technique for the qualitative and quantitative analysis of surface residues. The goal of this work was to study the application of diffuse reflectance mid-infrared spectroscopy to the identification of pesticide, herbicide, and explosive residues on surfaces. A field portable diffuse reflectance spectrometer was used to collect the mid-infrared spectra of clean surfaces and contaminated surfaces. These spectra were used as calibration sets to develop automated data analysis to classify or to identify residues on samples. In this presentation, the instrumentation and data process algorithms will be discussed.

Barber, T.E.; Ayala, N.L.; Jin, Hong; Drumheller, C.T. [Sam Houston State Univ., Huntsville, TX (United States)] [and others

1997-12-31

402

Spectroscopy Using the Tracker Video Analysis Program  

NSDL National Science Digital Library

Spectroscopy has important applications in many fields and deserves more attention than is the norm in introductory optics labs. This poster describes a set of inexpensive, quantitative spectroscopy experiments that use a digital camera to capture images of spectra and Tracker to measure their intensity profiles. The spectra, produced by a diffraction grating in front of the camera lens, include two laser spots with known wavelengths for calibration. Tracker's line profile tool generates a "live" plot of relative intensity versus wavelength, enabling students to interactively explore the spectra in detail. Experiments include gas and laser line spectra, thermal spectra, color filters and absorption, and fluorescence. Supported in part by NSF grant #DUE-0126439

Brown, Douglas

2010-08-11

403

Key dynamics of conserved asparagine in a cryptochrome/photolyase family protein by fourier transform infrared spectroscopy.  

PubMed

Cryptochromes (Crys) and photolyases (Phrs) are flavoproteins that contain an identical cofactor (flavin adenine dinucleotide, FAD) within the same protein architecture but whose physiological functions are entirely different. In this study, we investigated light-induced conformational changes of a cyanobacterium Cry/Phr-like protein (SCry-DASH) with UV-visible and Fourier transform infrared (FTIR) spectroscopy. We developed a system for measuring light-induced difference spectra under the concentrated conditions. In the presence of a reducing agent, SCry-DASH showed photoreduction to the reduced form, and we identified a signal unique for an anionic form in the process. Difference FTIR spectra enabled us to assign characteristic FTIR bands to the respective redox forms of FAD. An asparagine residue, which anchors the FAD embedded within the protein, is conserved not only in the cyanobacterial protein but also in Phrs and other Crys, including the mammalian clock-related Crys. By characterizing an asparagine-to-cysteine (N392C) mutant of SCry-DASH, which mimics an insect specific Cry, we identified structural changes of the carbonyl group of this conserved asparagine upon light irradiation. We also found that the N392C mutant is stabilized in the anionic form. We did not observe a signal from protonated carboxylic acid residues during the reduction process, suggesting that the carboxylic acid moiety would not be directly involved as a proton donor to FAD in the system. These results are in contrast to plant specific Crys represented by Arabidopsis thaliana Cry1 that carry Asp at the position. We discuss potential roles for this conserved asparagine position and functional diversity in the Cry/Phr frame. PMID:20828134

Iwata, Tatsuya; Zhang, Yu; Hitomi, Kenichi; Getzoff, Elizabeth D; Kandori, Hideki

2010-10-19

404

Trace detection of light elements by laser-induced breakdown spectroscopy (LIBS): Applications to non-conducting materials  

NASA Astrophysics Data System (ADS)

The existence as well as concentration of light (low-atomic number) elements is directly related to some of the most important properties of almost all materials. Thus, the development of a direct, fast, and sensitive spectroscopic method for the analytical quantification of these elements is considered an important continuing challenge in many fields. In this report, results obtained from previous as well as most recent studies regarding trace detection of light elements in non-conducting materials by laser-induced breakdown spectroscopy (LIBS) technique are reviewed for the first time. Firstly, we introduce investigations performed in the far- and vacuum-UV as well as UV-visible-NIR spectral domains, and cover many non-conducting materials including gases, aerosols, soil, cement, and selected organic compounds. The report also demonstrates important analytical results for the elements lithium, beryllium, boron, carbon, fluorine, phosphorus, sulfur, and chlorine. In addition, key characterization information relating to a specific element in a given matrix and state is summarized in such a way that relevant resources can easily be traced. Furthermore, in order to facilitate tracking down the evolution of the technique for a particular material category, a chronological order has been devised. In the second part of the review, the latest developments and advances in instrumentation and methodologies of the LIBS technique, particularly in the realm of light elements detection, are discussed. The sensitive detection of light elements in the UV-VIS-NIR is still unsatisfactory, and more work is needed in order to achieve better analytical performance in terms of precision, accuracy and limits of detection. The author anticipates that significant sensitivity improvements should be realized by combining LIBS, employing femtosecond laser pulses, with other diagnostic techniques based on probing the plasma via diode lasers.

Khater, Mohamed A.

2013-10-01

405

Stark effect spectroscopy of tryptophan.  

PubMed Central

The change in permanent dipole moment (magnitude of delta mu) for the transition from the 1La state to the ground state of tryptophan is the key photophysical parameter for the interpretation of tryptophan fluorescence spectra in terms of static and dynamic dielectric properties of the surrounding medium. We report measurement of this parameter by means of electric field effect (Stark) spectroscopy for N-acetyl-L-tryptophanamide (NATA) in two solvents, the single tryptophan containing peptide melittin, and 5-methoxytryptophan. The values ranged from 5.9 to 6.2 +/- 0.4 Debye/f for NATA and melittin, where f represents the local field correction. The 1Lb magnitude of delta mu was much smaller. Application of Stark spectroscopy to these chromophores required decomposition of the near-UV absorption into the 1La and 1Lb bands by measurement of the fluorescence excitation anisotropy spectrum and represents an extension of the method to systems where band overlap would normally preclude quantitative analysis of the Stark spectrum. The results obtained for 5-methoxytryptophan point out limitations of this method of spectral decomposition. The relevance of these results to the interpretation of steady-state and time-resolved spectroscopy of tryptophan is discussed. PMID:7787044

Pierce, D W; Boxer, S G

1995-01-01

406

Energy & Climate: Getting Quantitative  

NASA Astrophysics Data System (ADS)

A noted environmentalist claims that buying an SUV instead of a regular car is energetically equivalent to leaving your refrigerator door open for seven years. A fossil-fuel apologist argues that solar energy is a pie-in-the-sky dream promulgated by na"ive environmentalists, because there's nowhere near enough solar energy to meet humankind's energy demand. A group advocating shutdown of the Vermont Yankee nuclear plant claims that 70% of its electrical energy is lost in transmission lines. Around the world, thousands agitate for climate action, under the numerical banner ``350.'' Neither the environmentalist, the fossil-fuel apologist, the antinuclear activists, nor most of those marching under the ``350'' banner can back up their assertions with quantitative arguments. Yet questions about energy and its environmental impacts almost always require quantitative answers. Physics can help! This poster gives some cogent examples, based on the newly published 2^nd edition of the author's textbook Energy, Environment, and Climate.

Wolfson, Richard

2011-11-01

407

Explanatory chapter: quantitative PCR.  

PubMed

Quantitative PCR (qPCR), also called real-time PCR or quantitative real-time PCR, is a PCR-based technique that couples amplification of a target DNA sequence with quantification of the concentration of that DNA species in the reaction. This method enables calculation of the starting template concentration and is therefore a frequently used analytical tool in evaluating DNA copy number, viral load, SNP detection, and allelic discrimination. When preceded by reverse-transcription PCR, qPCR is a powerful tool to measure mRNA expression and is the gold standard for microarray gene expression data confirmation. Given the broad applications of qPCR and the many technical variations that have been developed, a brief survey of qPCR, including technical background, available chemistries, and data analysis techniques will provide a framework for both experimental design and evaluation. PMID:24011054

Dymond, Jessica S

2013-01-01

408

Quantitatively Probing the Al Distribution in Zeolites  

SciTech Connect

The degree of substitution of Si4+ by Al3+ in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. As the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and 27Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al-distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in the HBEA150 sample has been determined from a combination of these methods. This work was supported by the U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.

Vjunov, Aleksei; Fulton, John L.; Huthwelker, Thomas; Pin, Sonia; Mei, Donghai; Schenter, Gregory K.; Govind, Niranjan; Camaioni, Donald M.; Hu, Jian Z.; Lercher, Johannes A.

2014-06-11

409

Primary enzyme quantitation  

DOEpatents

The disclosure relates to the quantitation of a primary enzyme concentration by utilizing a substrate for the primary enzyme labeled with a second enzyme which is an indicator enzyme. Enzyme catalysis of the substrate occurs and results in release of the indicator enzyme in an amount directly proportional to the amount of primary enzyme present. By quantifying the free indicator enzyme one determines the amount of primary enzyme present.

Saunders, G.C.

1982-03-04

410

Quantitative nondestructive evaluation  

Microsoft Academic Search

Quantitative Nondestructive Evaluation (QNDE) provides techniques to assess deterioration of a material or a structure, and to detect and characterize discrete flaws. It plays, therefore, an important role in the prevention of failure. QNDE techniques are used in processing, manufacturing and for in-service inspection. QNDE is particularly important for the in-service inspection of high-cost and critical load-bearing structures whose failure

J. D Achenbach

2000-01-01

411

Computational vaccinology: quantitative approaches.  

PubMed

The immune system is hierarchical and has many levels, exhibiting much emergent behaviour. However, at its heart are molecular recognition events that are indistinguishable from other types of biomacromolecular interaction. These can be addressed well by quantitative experimental and theoretical biophysical techniques, and particularly by methods from drug design. We review here our approach to computational immunovaccinology. In particular, we describe the JenPep database and two new techniques for T cell epitope prediction. One is based on quantitative structure-activity relationships (a 3D-QSAR method based on CoMSIA and another 2D method based on the Free-Wilson approach) and the other on atomistic molecular dynamic simulations using high performance computing. JenPep (http://www.jenner.ar.uk/ JenPep) is a relational database system supporting quantitative data on peptide binding to major histocompatibility complexes, TAP transporters, TCR-pMHC complexes, and an annotated list of B cell and T cell epitopes. Our 2D-QSAR method factors the contribution to peptide binding from individual amino acids as well as 1-2 and 1-3 residue interactions. In the 3D-QSAR approach, the influence of five physicochemical properties (volume, electrostatic potential, hydrophobicity, hydrogen-bond donor and acceptor abilities) on peptide affinity were considered. Both methods are exemplified through their application to the well-studied problem of peptide binding to the human class I MHC molecule HLA-A*0201. PMID:14712934

Flower, Darren R; McSparron, Helen; Blythe, Martin J; Zygouri, Christianna; Taylor, Debra; Guan, Pingping; Wan, Shouzhan; Coveney, Peter V; Walshe, Valerie; Borrow, Persephone; Doytchinova, Irini A

2003-01-01

412

Quantitative chemical analysis  

SciTech Connect

Quantitative Chemical Analysis is an excellent text for a classical undergraduate course in quantitative analysis. The greatest strengths of the text are the superb organization and the programmed approach toward the presentation of the material. It is directed at an audience with a minimal background in chemistry (i.e., one year of freshman-level chemistry) and provides introductory material (i.e., basic organic chemistry, stoichiometry, and solution equilibria) in the first chapter for those who need it. The book covers the basic principles of the quantitative treatment of data, including the concepts of accuracy, precision, and basic statistical methods. As in any classical text on this subject, the text is biased toward methods involving solution equilibria. Consequently, the bulk of the discussion centers on gravimetric analysis, pH, complexation, and oxidation-reduction titrations. The principles of electroanalytical measurements are explained clearly, and several chapters on potentiometric and amperometric methods are adequately detailed. Supplementary information concerning the basics of the other instrumental techniques is provided in the last 10 chapters.

Manhan, S.L.

1986-01-01

413

Volume 58, Number 10, 2004 APPLIED SPECTROSCOPY 1165 0003-7028 / 04 / 5810-1165$2.00 / 0  

E-print Network

Society for Applied Spectroscopy Quantitative Analysis of Raman Signal Enhancement from Aqueous Samples the enhancement factor in different ways. Index Headings: Raman; Spectroscopy; Teflon; Waveguide; En- hancement. INTRODUCTION Vibrational Raman spectroscopy can provide a wealth of information about the chemicals present

Berger, Andrew J.

414

Scanning tunneling microscopy and tunneling spectroscopy of nano-structured H6P2MoxW(18-x)O62 (x = 0, 3, 9, 15, 18) Wells-Dawson heteropolyacids.  

PubMed

Scanning tunneling microscopy (STM) and tunneling spectroscopy studies of nano-structured H6P2MoxW(18-x)O62 (x = 0, 3, 9, 15, 18) Wells-Dawson heteropolyacids (HPAs) were carried out to examine redox properties of the HPAs. STM images of H6P2MoxW(18-x)O62 HPAs clearly showed self-assembled and well-ordered 2-dimensional arrays on graphite surface. Tunneling spectroscopy measurements revealed that all H6P2MoxW(18-x)O62 HPAs exhibited a negative differential resistance (NDR) behavior in their tunneling spectra. NDR peak voltage of H6P2MoxW(18-x)O62 HPAs appeared at less negative applied voltage with increasing molybdenum substitution. Reduction potential of H6P2MoxW(18-x)O62 HPAs measured by an electrochemical method increased and absorption edge energy determined by UV-visible spectroscopy shifted to lower value with increasing molybdenum substitution. In other words, NDR peak voltage of H6P2MoxW(18-x)O62 HPAs appeared at less negative applied voltage with increasing reduction potential and with decreasing absorption edge energy of the HPAs; more reducible H6P2MoxW(18-x)O62 HPAs showed NDR behavior at less negative applied voltage. These results indicate that NDR peak voltage of nano-structured HPAs measured by STM could be utilized as a correlating parameter for the redox properties of bulk HPAs. PMID:22121751

Choi, Jung Ho; Park, Dong Ryul; Park, Sunyoung; Song, In Kyu

2011-07-01

415

Quantitative Shape Analysis Radu Rugina  

E-print Network

Quantitative Shape Analysis Radu Rugina Computer Science Department Cornell University Ithaca, NY 14853 rugina@cs.cornell.edu Abstract. This paper presents a static analysis that computes quantitative structures and is able to extract quantitative information about the height and the balancing

Rugina, Radu

416

Quantitative Languages Krishnendu Chatterjee1  

E-print Network

Quantitative Languages Krishnendu Chatterjee1 , Laurent Doyen2 , and Thomas A. Henzinger2 1 University of California, Santa Cruz 2 EPFL, Lausanne, Switzerland Abstract. Quantitative generalizations with transition weights) to define several natural classes of quantitative languages over finite and infinite

Henzinger, Thomas A.

417

Compositional Quantitative Reasoning # Krishnendu Chatterjee  

E-print Network

Compositional Quantitative Reasoning # Krishnendu Chatterjee UC Berkeley Luca de Alfaro UC Santa can express a wide variety of quantitative system prop­ erties, such as resource consumption, price rules for compositional reasoning have quantitative counterparts in our setting. While our general

Henzinger, Thomas A.

418

Quantitative Methods II Winter 2012  

E-print Network

1 of 3 Quantitative Methods II Winter 2012 Meets: Thursdays 9am ­ 11:50am Professor: Jonathan.northwestern.edu This course is intended to be a continuation of the quantitative methods sequence that began with Quantitative assumptions are violated. We will then discuss various methods researchers use to overcome these obstacles

Bustamante, Fabián E.

419

Gasoline analysis by 1H nuclear magnetic resonance spectroscopy  

Microsoft Academic Search

High-resolution proton nuclear magnetic resonance (1H n.m.r.) spectroscopy allows the rapid and exact quantitative determination of the composition and quality of gasolines. For this study about 140 gasolines from Austrian filling stations were analysed. The amounts of methanol, methyl tert-butyl ether (MTBE), benzene and aromatics were determined quantitatively using an internal standard. These results were compared with data obtained by

Reinhard Meusinger

1996-01-01

420

Heterodyne laser spectroscopy system  

DOEpatents

A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

Wyeth, Richard W. (Livermore, CA); Paisner, Jeffrey A. (San Ramon, CA); Story, Thomas (Antioch, CA)

1989-01-01

421

Heterodyne laser spectroscopy system  

DOEpatents

A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

Wyeth, Richard W. (Livermore, CA); Paisner, Jeffrey A. (San Ramon, CA); Story, Thomas (Antioch, CA)

1990-01-01

422

318 Volume 56, Number 3, 2002 APPLIED SPECTROSCOPY 0003-7028 / 02 / 5603-0318$2.00 / 0  

E-print Network

of Organic Matter in Humin, Humic Acid, and Fulvic Acid Fractions in Soil Exposed to Elevated CO2 and N- mic substances (humin, HU; humic acid, HA; and fulvic acid, FA) extracted at a depth of 0­10 cm from increase of the acidic OH groups of the FA. Index Headings: FT-IR; UV-visible; X-ray diffraction; Soil

van Kessel, Chris

423

Quantitative Hyperspectral Reflectance Imaging  

PubMed Central

Hyperspectral imaging is a non-destructive optical analysis technique that can for instance be used to obtain information from cultural heritage objects unavailable with conventional colour or multi-spectral photography. This technique can be used to distinguish and recognize materials, to enhance the visibility of faint or obscured features, to detect signs of degradation and study the effect of environmental conditions on the object. We describe the basic concept, working principles, construction and performance of a laboratory instrument specifically developed for the analysis of historical documents. The instrument measures calibrated spectral reflectance images at 70 wavelengths ranging from 365 to 1100 nm (near-ultraviolet, visible and near-infrared). By using a wavelength tunable narrow-bandwidth light-source, the light energy used to illuminate the measured object is minimal, so that any light-induced degradation can be excluded. Basic analysis of the hyperspectral data includes a qualitative comparison of the spectral images and the extraction of quantitative data such as mean spectral reflectance curves and statistical information from user-defined regions-of-interest. More sophisticated mathematical feature extraction and classification techniques can be used to map areas on the document, where different types of ink had been applied or where one ink shows various degrees of degradation. The developed quantitative hyperspectral imager is currently in use by the Nationaal Archief (National Archives of The Netherlands) to study degradation effects of artificial samples and original documents, exposed in their permanent exhibition area or stored in their deposit rooms.

Klein, Marvin E.; Aalderink, Bernard J.; Padoan, Roberto; de Bruin, Gerrit; Steemers, Ted A.G.

2008-01-01

424

Drug analysis by Raman and micro-Raman spectroscopy.  

PubMed

The technique of Raman spectroscopy, resonance Raman spectroscopy and micro-Raman spectroscopy is described for application to drug analysis and investigation. Possibilities and limits are mentioned for qualitative and quantitative analyses as well as for studies of structure and interactions. Some principal interaction modes, such as hydrogen bonding, proton transfer, charge transfer and ion-molecule attraction, are shown to explain drug reactivity. Illustrations are given based on several drug families, in particular vitamins, anti-depressants, cardio-active and anticancer drugs. PMID:16867562

Huong, P V

1986-01-01

425

Biomolecular Plasmonics for Quantitative Biology and Nanomedicine  

PubMed Central

Free electrons in a noble metal nanoparticle can be resonantly excited, leading to their collective oscillation termed as a surface plasmon. These surface plasmons enable nanoparticles to absorb light, generate heat, transfer energy, and re-radiate incident photons. Creative designs of nanoplasmonic optical antennae (i.e. plasmon resonant nanoparticles) have become a new foundation of quantitative biology and nanomedicine. This review focuses on the recent developments in dual-functional nanoplasmonic optical antennae for label-free biosensors and nanoplasmonic gene switches. Nanoplasmonic optical antennae, functioning as biosensors to significantly enhance biochemical-specific spectral information via plasmon resonance energy transfer (PRET) and surface-enhanced Raman spectroscopy (SERS), are discussed. Nanoplasmonic optical antennae, functioning as nanoplasmonic gene switches to enable spatiotemporal regulation of genetic activity, are also reviewed. Nanoplasmonic molecular rulers and integrated photoacoustic-photothermal contrast agents are also described. PMID:20801636

Lee, Somin Eunice; Lee, Luke P.

2012-01-01

426

Field spectroscopy of agricultural crops  

NASA Technical Reports Server (NTRS)

The development of the full potential of multispectral data acquired from satellites, requires quantitative knowledge, and physical models of the spectral properties of specific earth surface features. Knowledge of the relationships between spectral-radiometric characteristics and important biophysical parameters of agricultural crops and soils can best be obtained by carefully controlled studies of fields or plots. It is important to select plots where data describing the agronomic-biophysical properties of the crop canopies and soil background are attainable, taking into account also the feasibility of frequent timely calibrated spectral measurements. The term 'field spectroscopy' is employed for this research. The present paper is concerned with field research which was sponsored by NASA as part of the AgRISTARS Supporting Research Project. Attention is given to field research objectives, field research instrumentation, measurement procedures, spectral-temporal profile modeling, and the effects of cultural and environmental factors on crop reflectance.

Bauer, M. E.; Daughtry, C. S. T.; Biehl, L. L.; Kanemasu, E. T.; Hall, F. G.

1986-01-01

427

Surface inspection using FTIR spectroscopy  

NASA Astrophysics Data System (ADS)

The use of reflectance Fourier transform infrared (FTIR) spectroscopy as a tool for surface inspection is described. Laboratory instruments and portable instruments can support remote sensing probes that can map chemical contaminants on surfaces with detection limits under the best of conditions in the sub-nanometer range, i.e.. near absolute cleanliness, excellent performance in the sub-micrometer range, and useful performance for films tens of microns thick. Examples of discovering and quantifying contamination such as mineral oils and greases, vegetable oils, and silicone oils on aluminum foil, galvanized sheet steel, smooth aluminum tubing, and sandblasted 7075 aluminum alloy and D6AC steel. The ability to map in time and space the distribution of oil stains on metals is demonstrated. Techniques associated with quantitatively applying oils to metals, subsequently verifying the application, and non-linear relationships between reflectance and the quantity oil are described.

Powell, G. L.; Smyrl, N. R.; Williams, D. M.; Meyers, H. M., III; Barber, T. E.; Marrero-Rivera, M.

1995-03-01

428

Surface inspection using FTIR spectroscopy  

NASA Technical Reports Server (NTRS)

The use of reflectance Fourier transform infrared (FTIR) spectroscopy as a tool for surface inspection is described. Laboratory instruments and portable instruments can support remote sensing probes that can map chemical contaminants on surfaces with detection limits under the best of conditions in the sub-nanometer range, i.e.. near absolute cleanliness, excellent performance in the sub-micrometer range, and useful performance for films tens of microns thick. Examples of discovering and quantifying contamination such as mineral oils and greases, vegetable oils, and silicone oils on aluminum foil, galvanized sheet steel, smooth aluminum tubing, and sandblasted 7075 aluminum alloy and D6AC steel. The ability to map in time and space the distribution of oil stains on metals is demonstrated. Techniques associated with quantitatively applying oils to metals, subsequently verifying the application, and non-linear relationships between reflectance and the quantity oil are described.

Powell, G. L.; Smyrl, N. R.; Williams, D. M.; Meyers, H. M., III; Barber, T. E.; Marrero-Rivera, M.

1995-01-01

429

Quantitative Chemical Imaging with Multiplex Stimulated Raman Scattering Microscopy  

PubMed Central

Stimulated Raman scattering (SRS) microscopy is a newly developed label-free chemical imaging technique that overcomes the speed limitation of confocal Raman while avoiding the nonresonant-background problem of coherent anti-Stokes Raman scattering (CARS) microscopy. Previous demonstrations were limited to single Raman band measurement. We present a novel modulation multiplexing approach that allows real-time detection of multiple species using the fast Fourier-transform. We demonstrate quantitative determination of chemical concentration of a ternary mixture. Furthermore, two imaging applications are pursued: (1) quantitative determination of oil content, as well as pigment and protein concentration in microalgae cultures; (2) 3D high resolution imaging of blood, lipids, and protein distribution in ex vivo mouse skin tissue. We believe quantitative multiplex SRS uniquely combines the advantage of fast label-free imaging with the fingerprinting capability of Raman spectroscopy and enables numerous applications lipid biology as well as biomedical imaging. PMID:22316340

Fu, Dan; Lu, Fa-Ke; Zhang, Xu; Freudiger, Christian; Pernik, Douglas R.; Holtom, Gary; Xie, Xiaoliang Sunney

2012-01-01

430

Quantitative evolutionary design  

PubMed Central

The field of quantitative evolutionary design uses evolutionary reasoning (in terms of natural selection and ultimate causation) to understand the magnitudes of biological reserve capacities, i.e. excesses of capacities over natural loads. Ratios of capacities to loads, defined as safety factors, fall in the range 1.2-10 for most engineered and biological components, even though engineered safety factors are specified intentionally by humans while biological safety factors arise through natural selection. Familiar examples of engineered safety factors include those of buildings, bridges and elevators (lifts), while biological examples include factors of bones and other structural elements, of enzymes and transporters, and of organ metabolic performances. Safety factors serve to minimize the overlap zone (resulting in performance failure) between the low tail of capacity distributions and the high tail of load distributions. Safety factors increase with coefficients of variation of load and capacity, with capacity deterioration with time, and with cost of failure, and decrease with costs of initial construction, maintenance, operation, and opportunity. Adaptive regulation of many biological systems involves capacity increases with increasing load; several quantitative examples suggest sublinear increases, such that safety factors decrease towards 1.0. Unsolved questions include safety factors of series systems, parallel or branched pathways, elements with multiple functions, enzyme reaction chains, and equilibrium enzymes. The modest sizes of safety factors imply the existence of costs that penalize excess capacities. Those costs are likely to involve wasted energy or space for large or expensive components, but opportunity costs of wasted space at the molecular level for minor components. PMID:12122135

Diamond, Jared

2002-01-01

431

Evaluation of cartilage defects with near-infrared spectroscopy (NIR): An ex vivo study  

Microsoft Academic Search

Damaged cartilage undergoes complex changes in composition, histological structure, and mechanical properties. Near-infrared-spectroscopy (NIR spectroscopy) is an important method to measure changes in composition of complex composites. The present study was aimed at evaluating NIR spectroscopy as a means to quantitate tissue alterations in low grade cartilage defects.Fresh medial femoral condyles from female sheep were collected. Cartilage defects were graded

Gunter Spahn; Holger Plettenberg; Horst Nagel; Enrico Kahl; Hans Michael Klinger; Thomas Mückley; Manfred Günther; Gunther O. Hofmann; Jürgen A. Mollenhauer

2008-01-01

432

Quantitative fMRI and oxidative neuroenergetics  

PubMed Central

The discovery of functional magnetic resonance imaging (fMRI) has greatly impacted neuroscience. The blood oxygenation level-dependent (BOLD) signal, using deoxyhemoglobin as an endogenous paramagnetic contrast agent, exposes regions of interest in task-based and resting-state paradigms. However the BOLD contrast is at best a partial measure of neuronal activity, because the functional maps obtained by differencing or correlations ignore the total neuronal activity in the baseline state. Here we describe how studies of brain energy metabolism at Yale, especially with 13C magnetic resonance spectroscopy and related techniques, contributed to development of quantitative functional brain imaging with fMRI by providing a reliable measurement of baseline energy. This narrative takes us on a journey, from molecules to mind, with illuminating insights about neuronal-glial activities in relation to energy demand of synaptic activity. These results, along with key contributions from laboratories worldwide, comprise the energetic basis for quantitative interpretation of fMRI data. PMID:22542993

Hyder, Fahmeed; Rothman, Douglas L.

2012-01-01

433

Quantitative Species Measurements In Microgravity Combustion Flames  

NASA Technical Reports Server (NTRS)

The capability of models and theories to accurately predict and describe the behavior of low gravity flames can only be verified by quantitative measurements. Although video imaging, simple temperature measurements, and velocimetry methods have provided useful information in many cases, there is still a need for quantitative species measurements. Over the past decade, we have been developing high sensitivity optical absorption techniques to permit in situ, non-intrusive, absolute concentration measurements for both major and minor flames species using diode lasers. This work has helped to establish wavelength modulation spectroscopy (WMS) as an important method for species detection within the restrictions of microgravity-based measurements. More recently, in collaboration with Prof. Dahm at the University of Michigan, a new methodology combining computed flame libraries with a single experimental measurement has allowed us to determine the concentration profiles for all species in a flame. This method, termed ITAC (Iterative Temperature with Assumed Chemistry) was demonstrated for a simple laminar nonpremixed methane-air flame at both 1-g and at 0-g in a vortex ring flame. In this paper, we report additional normal and microgravity experiments which further confirm the usefulness of this approach. We also present the development of a new type of laser. This is an external cavity diode laser (ECDL) which has the unique capability of high frequency modulation as well as a very wide tuning range. This will permit the detection of multiple species with one laser while using WMS detection.

Chen, Shin-Juh; Pilgrim, Jeffrey S.; Silver, Joel A.; Piltch, Nancy D.

2003-01-01

434

Complementary TEM and AFM Force Spectroscopy to Characterize the  

E-print Network

force vs displacement (force spectroscopy) measurements made with an AFM tip and an aggregate manipulation device (NSMD) which made it possible to apply tension to nanostructures mounted in the TEM. NSMD to be studied quantitatively. This paper describes force vs displacement measurements of the interactions

Gimzewski, James

435

ANALYSIS OF ATMOSPHERIC ORGANIC AEROSOLS BY MASS SPECTROSCOPY  

EPA Science Inventory

High resolution mass spectroscopy has been found to be a useful means of characterizing the organic fraction of urban aerosols. Quantitative accuracy, however, was limited, particularly for compounds of low abundance. Some ambiguities were found in the assignment of origins of io...