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1

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

Microsoft Academic Search

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

Akihisa Nonoyama

2004-01-01

2

Imaging UV/Visible Spectroscopy: Is there a Future?  

NASA Astrophysics Data System (ADS)

A number of studies of large (4 to 16 meter class) ultraviolet and visible space telescopes are underway. Unfortunately the emphasis is on surveys with large fields, studies of the intergalactic medium or imaging of earth-like planets with emphasis on `killer applications'. To date, a full complement of instruments designed to support a balanced astronomy program has not been included. Spectroscopy, especially imaging spectroscopy that takes advantage of angular resolution approaching the diffraction limit of the primary mirror, is treated as an add-on, rather than an integral component in these telescope designs. Studies of specific complex objects whether they be a galaxy, stars within a globular cluster, stars with mass loss, star formation regions or proto-planetary disks, would benefit immensely with an advanced version of the Space Telescope Imaging Spectrograph.

Gull, Theodore R.

2009-05-01

3

Drug-DNA interactions and their study by UV-Visible, fluorescence spectroscopies and cyclic voltametry.  

PubMed

The present paper review the drug-DNA interactions, their types and applications of experimental techniques used to study interactions between DNA and small ligand molecules that are potentially of pharmaceutical interest. DNA has been known to be the cellular target for many cytotoxic anticancer agents for several decades. Understanding how drug molecules interact with DNA has become an active research area at the interface between chemistry, molecular biology and medicine. In this review article, we attempt to bring together topics that cover the breadth of this large area of research. The interaction of drugs with DNA is a significant feature in pharmacology and plays a vital role in the determination of the mechanisms of drug action and designing of more efficient and specifically targeted drugs with lesser side effects. Several instrumental techniques are used to study such interactions. In the present review, we will discuss UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The applications of spectroscopic techniques are reviewed and we have discussed the type of information (qualitative or quantitative) that can be obtained from the use of each technique. Not only have novel techniques been applied to study drug-DNA interactions but such interactions may also be the basis for the development of new assays. The interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases. PMID:23648795

Sirajuddin, Muhammad; Ali, Saqib; Badshah, Amin

2013-04-06

4

Moving beyond traditional UV-visible absorption detection: cavity ring-down spectroscopy for HPLC.  

PubMed

We describe the use of liquid-phase continuous-wave cavity ring-down spectroscopy for the detection of an HPLC separation. This technique builds on earlier work by Snyder and Zare using pulsed laser sources and improves upon commercially available UV-visible detectors by a factor of up to 50. The system employs a compact doubled-diode single-mode continuous-wave laser operating at 488 nm and a previously described Brewster's-angle flow cell. Ring-down time constants as long as 5.8 micros were observed with liquid samples in a 0.3-mm path length cell. The baseline noise during an HPLC separation was only 2 x 10(-7) absorbance units (AU) peak to peak, as compared to 1 x 10(-5) AU for a state-of-the-art commercial UV-visible detector. PMID:15859003

Bechtel, Kate L; Zare, Richard N; Kachanov, Alexander A; Sanders, Steve S; Paldus, Barbara A

2005-02-15

5

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

Microsoft Academic Search

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

Bradley Lyn Grunden

1999-01-01

6

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.

Agatonovic-Kustrin, Snezana; Morton, David W.

2012-01-01

7

Monitoring Light-induced Structural Changes of Channelrhodopsin-2 by UV-visible and Fourier Transform Infrared Spectroscopy*  

PubMed Central

Channelrhodopsin-2 (ChR2) is a microbial type rhodopsin and a light-gated cation channel that controls phototaxis in Chlamydomonas. We expressed ChR2 in COS-cells, purified it, and subsequently investigated this unusual photoreceptor by flash photolysis and UV-visible and Fourier transform infrared difference spectroscopy. Several transient photoproducts of the wild type ChR2 were identified, and their kinetics and molecular properties were compared with those of the ChR2 mutant E90Q. Based on the spectroscopic data we developed a model of the photocycle comprising six distinguishable intermediates. This photocycle shows similarities to the photocycle of the ChR2-related Channelrhodopsin of Volvox but also displays significant differences. We show that molecular changes include retinal isomerization, changes in hydrogen bonding of carboxylic acids, and large alterations of the protein backbone structure. These alterations are stronger than those observed in the photocycle of other microbial rhodopsins like bacteriorhodopsin and are related to those occurring in animal rhodopsins. UV-visible and Fourier transform infrared difference spectroscopy revealed two late intermediates with different time constants of ? = 6 and 40 s that exist during the recovery of the dark state. The carboxylic side chain of Glu90 is involved in the slow transition. The molecular changes during the ChR2 photocycle are discussed with respect to other members of the rhodopsin family.

Ritter, Eglof; Stehfest, Katja; Berndt, Andre; Hegemann, Peter; Bartl, Franz J.

2008-01-01

8

Determination of pKa of felodipine using UV-Visible spectroscopy  

NASA Astrophysics Data System (ADS)

In the present study, for the first time, experimental pKa value of felodipine is reported. Dissociation constant, pKa, is one of the very important physicochemical properties of drugs. It is of paramount significance from the perspective of pharmaceutical analysis and dosage form design. The method used for the pKa determination of felodipine was essentially a UV-Visible spectrophotometric method. The spectrophotometric method for the pKa determination was opted by acknowledging the established fact that spectrophotometric determination of pKa produces most precise values. The pKa of felodipine was found to be 5.07. Furthermore, the ruggedness of the determined value is also validated in this study in order to produce exact pKa of the felodipine.

Pandey, M. M.; Jaipal, A.; Kumar, A.; Malik, R.; Charde, S. Y.

2013-11-01

9

In situ UV-visible reflection absorption wavelength modulation spectroscopy of species irreversibly adsorbed on electrode surfaces  

SciTech Connect

A method is herein described for the in situ detection of species adsorbed on electrode surfaces which employs a vibrating grating to modulate the wavelength of the incident light. This technique denoted as reflection absorption wavelength modulation spectroscopy (RAWMS) has made it possible to obtain at a fixed electrode potential normalized, differential UV-visible spectra of a single, irreversibly adsorbed monolayer of cobalt tetrasulfonated phthalocyanine (Co[sup II]TsPc) on the basal plane of highly oriented pyrolytic graphite (HOPG(bp)) and of methylene blue (MB) on graphite. The (wavelength) integrated difference RAWMS spectra for these adsorbed species were remarkably similar to those observed for the same compounds in aqueous solutions when present in the monomeric form. Complementary wavelength modulation experiments involving a conventional transmission geometry have shown that the instrument involved in the in situ RAWMS measurements is capable of resolving absorbance changes on the order of 0.002 units. 20 refs.

Kim, Sunghyun; Scherson, D.A. (Case Western Reserve Univ., Cleveland, OH (United States))

1992-12-15

10

A kinetic study on the formation of poly(4 aminodiphenylamine)/copper nanocomposite using UV-visible spectroscopy  

NASA Astrophysics Data System (ADS)

The course of the reaction between copper sulfate (CuSO4) and 4-aminodiphenylamine (4ADPA) was monitored by UV-visible spectroscopy in p-toluene sulfonic acid (p-TSA). Formation of poly(4-aminodiphenylamine)/copper nanoparticle composite (P4ADPA/CuNC) was witnessed through the steady increase in absorbance at 410, 580 and >700 nm. The absorbance at 410 nm as well as >700 nm are correlated to the amount of P4ADPA/CuNC formation and was subsequently used to determine the rate of formation of P4ADPA/CuNC (RP4ADPA/CuNC) at any time during the course of the reaction. RP4ADPA/CuNC shows a first-order dependence on [4ADPA] and a half-order dependence on [CuSO4]. A kinetic rate expression was established between RP4ADPA/CuNC and experimental parameters such as [4ADPA] and [CuSO4]. The rate constant for the formation of P4ADPA/CuNC was 8.98 × 10-3 mol-0.5 l0.5 s-1. Field emission scanning electron and transmission electron micrographs revealed that the morphology of the P4ADPA/CuNC was influenced by the reaction conditions.

Starlet Thanjam, I.; Francklin Philips, M.; Manisankar, P.; Lee, Kwang-Pill; Gopalan, A.

2013-12-01

11

UV-visible absorption spectroscopy for the detection of differences in oligonucleotide influenced aggregation of colloidal gold nanoparticles  

NASA Astrophysics Data System (ADS)

Transposable elements (TEs) or transposons are mobile segments of DNA that are capable of being excised and moved from one chromosomal location to another by a process known as transposition. This process requires an enzyme called the transposase that performs the excision reaction, recognizes specific target site sequences and then promotes insertion of the TE at the target site (transposition). This study provides new clues towards unraveling the causes behind the preferential affinity of the Hermes transposable element for certain insertion sites compared to other sequences which also contain recognizable target sites. The technique consists of a rapid, simple and reproducible assay that can be used to detect differences in the ability of various oligonucleotides to influence the aggregation of colloidal gold nanoparticles. The aggregation of the gold nanoparticles is monitored through UV-Visible absorption spectroscopy. Single isolated colloidal gold particles have a surface plasmon resonance manifested as a single absorbance peak at approximately 520 nm and aggregated gold complexes develop new red-shifted peaks/shoulders depending on the nature and extent of the aggregated complex. A simple ratiometric study of the area under the single and aggregated plasmon resonance peaks gives information about the extent of the aggregation. It is postulated that differences in dynamic flexibility of the oligonucleotides affect their influence on the aggregation state of the gold nanoparticles. Therefore such differences in dynamic flexibility between various insertion sites could directly or indirectly contribute to the observed target site preferences of the Hermes transposable element.

Chowdury, Mustafa H.; Julian, Andrea M.; Coates, Craig J.; Cote, Gerard L.

2005-04-01

12

Analysis of Mexico City urban air pollution using nitrogen dioxide column density measurements from UV/Visible spectroscopy  

NASA Astrophysics Data System (ADS)

The differential optical absorption spectroscopy method (DOAS) was used to get column densities of nitrogen dioxide (NO2) from the analysis of zenith sky UV/visible spectra. Since the optical path length provides critical information in interpreting NO2 column densities, in conjunction with NO2 column densities, the oxygen dimer (O4) column density was retrieved to give insight into the optical path length. We report observations of year round NO2 and O4 column densities (from august 2009 to september 2010) from which the mean seasonal levels and the daily evolution, as well as the occurrence of elevated pollution episodes are examined. Surface nitric oxide (NO) and NO2 from the local monitoring network, as well as wind data and the vertical aerosol density from continuous Lidar measurements are used in the analysis to investigate specific events in the context of local emissions from vehicular traffic, photochemical production and transport from industrial emissions. The NO2 column density measurements will enhance the understanding Mexico City urban air pollution. Recent research has begun to unravel the complexity of the air pollution problem in Mexico City and its effects not only locally but on a regional and global scale as well.

Garcia Payne, D. G.; Grutter, M.; Melamed, M. L.

2010-12-01

13

Evaluation of a second derivative UV/visible spectroscopy technique for nitrate and total nitrogen analysis of wastewater samples.  

PubMed

A method for nitrate analysis based on second derivative UV/Visible spectroscopy was developed by Simal et al. (1985: Simal J., Lage M. A., and Iglesias I. (1985) Second derivative ultraviolet spectroscopy and sulfamic acid method for determination of nitrates in water. J. Assoc. Analyt. Chem. 68, 962-964) and Suzuki and Kuroda (1987: Suzuki, N. and Kuroda R. (1987) Direct simultaneous determination of nitrate and nitrite by ultraviolet second-derivative spectrophotometry. Analyst 112, 1077-1079), and later modified for the analysis of total nitrogen in aqueous samples of varying nitrate:organic nitrogen ratios (Crumpton et al., 1992: Crumption W. G., Isenhart T. M. and Mitchell P. D. (1992) Nitrate and organic N analyses with second-derivative spectroscopy. Limnol. Oceanogr. 37, 907-913). The procedure uses the second derivative of the absorption spectrum for nitrate (NO3-), which has a peak at approximately 224 nm that is proportional to the NO3- concentration. Samples for total N analysis are first oxidized to NO3- by persulfate digestion. The objectives of this study were to: (1) test the accuracy and precision of the second derivative method through the use of NIST-traceable wastewater check samples; (2) determine whether the second derivative method for nitrate analysis can be used for wastewater samples and whether the method compares favorably with other currently used nitrate analysis methods; and (3) use the method to analyze wastewater samples containing a range of nitrate and total nitrogen concentrations. Our results indicated that the method needed to be modified to include a longer digestion time (60 min) and dilution of samples prior to digestion (if needed). With the modified method, nitrogen recoveries were not significantly different (P > or = 0.05) from samples with known N concentrations. In addition, nitrate concentrations in constructed wetland and wastewater samples analyzed by both second derivative spectroscopy and ion chromatography were not significantly different. Total nitrogen concentrations in wastewater samples also compared favorably to the same samples analyzed by Kjeldahl digestion. The method is faster, simpler, requires smaller sample volumes, and generates less waste than many EPA-approved methods of N analysis, and may offer a suitable alternative to current methods for analysis of nitrate and total N in wastewater samples. PMID:11257889

Ferree, M A; Shannon, R D

2001-01-01

14

IN-VIVO DIAGNOSIS OF CHEMICALLY INDUCED MELANOMA IN AN ANIMAL MODEL USING UV-VISIBLE AND NIR ELASTIC SCATTERING SPECTROSCOPY: PRELIMINARY TESTING.  

SciTech Connect

Elastic light scattering spectroscopy (ESS) has the potential to provide spectra that contain both morphological and chromophore information from tissue. We report on a preliminary study of this technique, with the hope of developing a method for diagnosis of highly-pigmented skin lesions, commonly associated with skin cancer. Four opossums were treated with dimethylbenz(a)anthracene to induce both malignant melanoma and benign pigmented lesions. Skin lesions were examined in vivo using both UV-visible and near infrared (NIR) ESS, with wavelength ranges of 330-900 nm and 900-1700 nm, respectively. Both portable systems used identical fiber-optic probe geometry throughout all of the measurements. The core diameters for illuminating and collecting fibers were 400 and 200 {micro}m, respectively, with center-to-center separation of 350 {micro}m. The probe was placed in optical contact with the tissue under investigation. Biopsies from lesions were analyzed by two standard histopathological procedures. Taking into account only the biopsied lesions, UV-visible ESS showed distinct spectral correlation for 11/13 lesions. The NIR-ESS correlated well with 12/13 lesions correctly. The results of these experiments showed that UV-visible and NIR-ESS have the potential to classify benign and malignant skin lesions, with encouraging agreement to that provided by standard histopathological examination. These initial results show potential for ESS based diagnosis of pigmented skin lesions, but further trials are required in order to substantiate the technique.

C. A'AMAR; R. LEY; ET AL

2001-01-01

15

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

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

2009-04-28

16

Evaluation of poly-Si thin film crystallized by solid green laser annealing using UV\\/visible Raman spectroscopy  

Microsoft Academic Search

Depth and in-plane distributions of the crystal qualities in low-temperature polycrystalline Si (LTPS) films fabricated by\\u000a green laser annealing with s and p-polarizations and commercial excimer laser annealing were evaluated by Raman spectroscopy\\u000a with UV and visible excitation laser sources from the front and back surfaces. A quasi-line excitation source provides a one-dimensional\\u000a profile with 200-nm spatial resolution and step-by-step

Atsushi Ogura; Yasuto Kakemura; Daisuke Kosemura; Tetsuya Yoshida; Miyuki Masaki; Kenichirou Nishida; Ryusuke Kawakami; Naoya Yamamoto

2008-01-01

17

Interaction of flavonoids, the naturally occurring antioxidants with different media: A UV-visible spectroscopic study  

NASA Astrophysics Data System (ADS)

Quantitative parameters for interaction of flavonoids—the naturally occurring antioxidants, with solvents and surfactants are determined using UV-visible absorption spectroscopy. The availability of flavonoids; kaempferol, apigenin, kaempferide and rhamnetin in micelles of sodium dodecyl sulfate (SDS) is reflected in terms of partition coefficient, Kc. Thermodynamic calculations show that the process of transfer of flavonoid molecules to anionic micelles of SDS is energy efficient. A distortion in flavonoid's morphology occurs in case of kaempferol and apigenin in surfactant and water, exhibited in terms of a new band in the UV region of electronic spectra of these flavonoids. The partition coefficients of structurally related flavonoids are correlated with their antioxidant activities.

Naseem, Bushra; Shah, S. W. H.; Hasan, Aurangzeb; Sakhawat Shah, S.

2010-04-01

18

Proof by UV-visible modulated reflectance spectroscopy of the breakdown by carbonation of the passivating layer on iron in alkaline solution  

Microsoft Academic Search

Carbonation of concrete by atmospheric CO2 may lead to breakdown of the passivating layer of the steel reinforcements, leading to catastrophic corrosion, if the pH of the electrolyte in the concrete pores decreases below 8. The nature of this carbonation process has been studied by means of potential-modulated reflectance (PMR) spectroscopy, following the changes in the PMR spectrum of air-passivated

Miguel A. Climent; Claudio Gutiérrez

1995-01-01

19

Aggregation state and pKa values of (E)-resveratrol as determined by fluorescence spectroscopy and UV-visible absorption.  

PubMed

Whether or not (E)-resveratrol can be used as a functional ingredient in foods depends on its structure at different concentrations and pH values. For this reason, the aggregation state of (E)-resveratrol at acidic and basic pH is investigated here for the first time. The data show that (E)-resveratrol forms aggregates above a certain critical concentration, and this concentration is lower at acid (12.5 microM at pH 5.5) than at basic pH values (37 microM at pH 10.5). Moreover, although several papers have focused on the effect of the protonation state of (E)-resveratrol on its biological activity, different data concerning the acidic dissociation constants of this natural antioxidant have been reported in the literature. The present paper shows a way of determining the acidic dissociation constants (pKa1 = 8.8, pKa2 = 9.8, pKa3 = 11.4) of (E)-resveratrol in aqueous medium using both absorbance and fluorescence spectroscopy. Furthermore, the spectroscopic study of (E)-resveratrol under different ionization states corresponding to the deprotonation of the hydroxyl groups present in the molecule shows significant differences among the absorbance, excitation, and emission spectra of (E)-resveratrol that have not previously been reported. PMID:18700778

López-Nicolás, José Manuel; García-Carmona, Francisco

2008-08-14

20

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, Ka,COOH, and the first and second ionization constants for glycine, Ka,COOH and Ka,NH4+, have been determined at temperatures as high as 250°C. Values for the standard partial molar heat capacity of ionization, ?rCpo,COOH and ?rCpo,NH4+, have been determined from the temperature dependence of ln (Ka,COOH) and ln (Ka,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

21

Uv-visible spectroscopy of bacteriorhodopsin mutants: Substitution of Arg-82, Asp-85, Tyr-185, and Asp-212 results in abnormal light-dark adaptation  

SciTech Connect

The light-dark adaptation reactions of a set of bacteriorhodopsin (bR) mutants that affect function and color of the chromophore were examined by using visible absorption spectroscopy. The absorbance spectra of the mutants Arg-82 in equilibrium Ala (Gln), Asp-85 in equilibrium Ala (Asn, Glu), Tyr-185 in equilibrium Phe, and Asp-212 in equilibrium Ala (Asn, Glu) were measured at different pH values during and after illumination. None of these mutants exhibited a normal dark-light adaptation, which in wild-type bR causes a red shift of the visible absorption maximum from 558 nm (dark-adapted bR) to 568 nm (light-adapted bR). Instead a reversible light reaction occurs in the Asp-85 and Asp-212 mutants from a blue form with lambda max near 600 nm to a pink form with lambda max near 480 nm. This light-induced shift explains the appearance of a reversed light adaptation previously observed for the Asp-212 mutants. In the case of the Tyr-185 and Arg-82 mutants, light causes a purple-to-blue transformation similar to the effect of lowering the pH. However, the blue forms observed in these mutants are not identical to those formed by acid titration or deionization of wild-type bR. It is suggested that in all of these mutants, the chromophore has lost the ability to undergo the normal 13-cis, 15-syn to all-trans, 15-anti light-driven isomerization, which occurs in native bR. Instead these mutants may have as stable forms all-trans,syn and 13-cis,anti chromophores, which are not allowed in native bR, except transiently.

Dunach, M.; Marti, T.; Khorana, H.G.; Rothschild, K.J. (Boston Univ., MA (USA))

1990-12-01

22

Quantitative analysis of manganese, chromium and molybdenum by ion-pair reversed-phase high-performance liquid chromatography with pre-column derivatization and UV-visible detection  

Microsoft Academic Search

An ion-pair reversed-phase high-performance liquid chromatographic method with UV–visible spectrophotometric detection is proposed for the simultaneous determination of manganese, chromium and molybdenum. By using a C18-bonded silica column, 4-(2-pyridylazo)resorcinol (PAR) chelates of Mn(II), Cr(VI) and Mo(VI) were successfully separated and accurately determined at 480 nm. Tetrabutylammonium bromide (TBAB) was used as the ion-pair reagent. Effects of pH, the buffer system,

Huang-Ling Sun; Hui-Ming Liu; Suh-Jen Jane Tsai

1999-01-01

23

Quantitative Spectroscopy of Deneb  

Microsoft Academic Search

Context: Quantitative spectroscopy of luminous BA-type supergiants offers a high potential for modern astrophysics. Detailed studies allow the evolution of massive stars, galactochemical evolution, and the cosmic distance scale to be constrained observationally. Aims: A detailed and comprehensive understanding of the atmospheres of BA-type supergiants is required in order to use this potential properly. The degree to which we can

Florian Schiller; Norbert Przybilla

2007-01-01

24

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.

Rinehart, Matthew; Zhu, Yizheng; Wax, Adam

2012-01-01

25

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

2012-06-04

26

Comparison of box-air-mass-factors and radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) geometries calculated from different UV\\/visible radiative transfer models  

Microsoft Academic Search

The results of a comparison exercise of radiative transfer models (RTM) of various international research groups for Multiple AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) viewing geometry are presented. Besides the assessment of the agreement between the different models, a second focus of the comparison was the systematic investigation of the sensitivity of the MAX-DOAS technique under various viewing geometries and

T. Wagner; J. P. Burrows; T. Deutschmann; B. Dix; C. von Friedeburg; U. Frieß; F. Hendrick; K.-P. Heue; H. Irie; H. Iwabuchi; Y. Kanaya; J. Keller; C. A. McLinden; H. Oetjen; E. Palazzi; A. Petritoli; U. Platt; O. Postylyakov; J. Pukite; A. Richter; M. van Roozendael; A. Rozanov; V. Rozanov; R. Sinreich; S. Sanghavi; F. Wittrock

2007-01-01

27

Comparison of Box-Air-Mass-Factors and Radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) Geometries calculated from different UV\\/visible Radiative Transfer Models  

Microsoft Academic Search

The results of a comparison exercise of radiative transfer models (RTM) of various international research groups for Multiple AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) viewing geometry are presented. In contrast to previous comparison exercises, box-air-mass-factors (box-AMFs) for various atmospheric height layers were modelled, which describe the sensitivity of the measurements as a function of altitude. In addition, radiances were calculated

T. Wagner; J. P. Burrows; T. Deutschmann; B. Dix; C. von Friedeburg; U. Frieß; F. Hendrick; K.-P. Heue; H. Irie; H. Iwabuchi; Y. Kanaya; J. Keller; C. A. McLinden; H. Oetjen; E. Palazzi; A. Petritoli; U. Platt; O. Postylyakov; J. Pukite; A. Richter; M. van Roozendael; A. Rozanov; V. Rozanov; R. Sinreich; S. Sanghavi; F. Wittrock

2006-01-01

28

SPECTRAL PROPERTIES OF SOOT IN THE UV-VISIBLE RANGE  

Microsoft Academic Search

The UV-Visible spectroscopic features of tarry and solid carbon species produced in premixed flames burning aliphatic (ethylene, n-hexane, cyclohexane, n-heptane) and aromatic fuels (benzene) were investigated in terms of spectral shape and mass specific absorption coefficients. The spectral properties of dry soot showed significant changes as a function of the flame position and of C\\/O ratio. Moreover, some peculiarities of

A. TREGROSSI; R. BARBELLA; A. CIAJOLO; M. ALFÈ

2007-01-01

29

Algorithm description for the retrieval of altitude and chemical information from ground-based UV-visible DOAS measurements  

Microsoft Academic Search

An algorithm has been developed to retrieve altitude information at different diurnal stages for trace gas species by combining the direct-sun and zenith-sky UV-Visible Differential Optical Absorption Spectroscopy (DOAS) measurements. It is the unique approach of combining the complementary zenith-sky measurements (sensitive to the stratosphere) with the direct-sun measurements (sensitive to the troposphere) that allows this vertical distinction. Trace gas

R. Schofield; B. Connor; K. Kreher; P. Johnston; C. Rodgers

2002-01-01

30

Synchrotron UV-visible multispectral luminescence microimaging of historical samples.  

PubMed

UV-visible luminescence techniques are fre-quently used for the study of cultural heritage materials, despite their limitations for identification and discrimination in the case of complex heterogeneous materials. In contrast to tabletop setups, two methods based on the vacuum ultraviolet (VUV)-UV-visible emission generated at a bending magnet of a synchrotron source are described. The main advantages of the source are the extended wavelength range attained, the continuous tunability of the source, and its brightness, leading to a submicrometer lateral resolution. Raster-scanning microspectroscopy and full-field microimaging were implemented and tested at the DISCO beamline (synchrotron SOLEIL, France). Investigative measurements were performed on a sample from a varnished musical instrument and a paint sample containing the pigment zinc white (ZnO) in order to illustrate some of the challenges analyzing heterogeneous cultural heritage cross-section samples with the novel imaging approach. The data sets obtained proved useful for mapping organic materials at the submicrometer scale and visualizing heterogeneities of the semiconductor pigment material. We propose and discuss the combined use of raster-scanning microspectroscopy and full-field microimaging in an integrated analytical methodology. Synchrotron UV luminescence appears as a novel tool for identification of craftsmen's and artists' materials and techniques and to assess the condition of artifacts, from the precise identification and localization of luminescent materials. PMID:21291177

Thoury, Mathieu; Echard, Jean-Philippe; Réfrégiers, Matthieu; Berrie, Barbara; Nevin, Austin; Jamme, Frédéric; Bertrand, Loïc

2011-02-03

31

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

32

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

33

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...

34

Homogenization of UV-Visible NDACC spectrometers reprocessing for ozone and NO2  

NASA Astrophysics Data System (ADS)

SAOZ is a ground-based UV-Visible zenith-sky spectrometer deployed since 1988 at a number of NDACC (Network for the Detection of Atmospheric Composition Change) stations at all latitudes on the globe. The instrument is providing ozone and NO2 total columns at sunrise and sunset using the Differential Optical Absorption Spectroscopy (DOAS) technique in the visible spectral range. SAOZ observations have been used extensively to validate various atmospheric chemistry satellite instruments such as nadir viewing TOMS, GOME, SCIAMACHY, OMI and GOME-2. The NDACC UV-Visible working group initiated a tentative homogenization of ozone and NO2 processing of all UV-Vis zenith sky spectrometers as one of its objectives. The first recommendation is concerning the total ozone retrieval. A significant change for the SAOZ network is the use of different cross-sections (O3, NO2, H2O, O4, and Ring calculations) and different spectral window fitting range, which leads to a recalculation of the slant columns. In addition, it is recommended to use a climatological air mass factor (AMF) instead of an annual AMF usually used in standard SAOZ processing. Here we present the results of comparisons between TOMS (since 1988), GOME (since 1995), SCIAMACHY (since 2002), OMI (since 2004), GOME-2 (since 2006) and SAOZ at all latitudes - tropics, mid-latitudes and Polar Regions - in both hemispheres. In the case of ozone, the NDACC recommendations resulted in a significant improvement of the differences between ground-based SAOZ and measurements from space. Preliminary results of NO2 SAOZ columns, using climatological AMF, are also presented and compared to different satellites, such as GOME, SCIAMACHY and OMI.

Pazmino, Andrea

2010-05-01

35

Development of an online UV-visible microspectrophotometer for a macromolecular crystallography beamline  

PubMed Central

Measurement of the UV–visible absorption spectrum is a convenient technique for detecting chemical changes of proteins, and it is therefore useful to combine spectroscopy and diffraction studies. An online microspectrophotometer for the UV–visible region was developed and installed on the macromolecular crystallography beamline, BL38B1, at SPring-8. This spectrophotometer is equipped with a difference dispersive double monochromator, a mercury–xenon lamp as the light source, and a photomultiplier as the detector. The optical path is mostly constructed using mirrors, in order to obtain high brightness in the UV region, and the confocal optics are assembled using a cross-slit diaphragm like an iris to eliminate stray light. This system can measure optical densities up to a maximum of 4.0. To study the effect of radiation damage, preliminary measurements of glucose isomerase and thaumatin crystals were conducted in the UV region. Spectral changes dependent on X-ray dose were observed at around 280?nm, suggesting that structural changes involving Trp or Tyr residues occurred in the protein crystal. In the case of the thaumatin crystal, a broad peak around 400?nm was also generated after X-ray irradiation, suggesting the cleavage of a disulfide bond. Dose-dependent spectral changes were also observed in cryo-solutions alone, and these changes differed with the composition of the cryo-solution. These responses in the UV region are informative regarding the state of the sample; consequently, this device might be useful for X-ray crystallography.

Shimizu, Nobutaka; Shimizu, Tetsuya; Baba, Seiki; Hasegawa, Kazuya; Yamamoto, Masaki; Kumasaka, Takashi

2013-01-01

36

Development of an online UV-visible microspectrophotometer for a macromolecular crystallography beamline.  

PubMed

Measurement of the UV-visible absorption spectrum is a convenient technique for detecting chemical changes of proteins, and it is therefore useful to combine spectroscopy and diffraction studies. An online microspectrophotometer for the UV-visible region was developed and installed on the macromolecular crystallography beamline, BL38B1, at SPring-8. This spectrophotometer is equipped with a difference dispersive double monochromator, a mercury-xenon lamp as the light source, and a photomultiplier as the detector. The optical path is mostly constructed using mirrors, in order to obtain high brightness in the UV region, and the confocal optics are assembled using a cross-slit diaphragm like an iris to eliminate stray light. This system can measure optical densities up to a maximum of 4.0. To study the effect of radiation damage, preliminary measurements of glucose isomerase and thaumatin crystals were conducted in the UV region. Spectral changes dependent on X-ray dose were observed at around 280?nm, suggesting that structural changes involving Trp or Tyr residues occurred in the protein crystal. In the case of the thaumatin crystal, a broad peak around 400?nm was also generated after X-ray irradiation, suggesting the cleavage of a disulfide bond. Dose-dependent spectral changes were also observed in cryo-solutions alone, and these changes differed with the composition of the cryo-solution. These responses in the UV region are informative regarding the state of the sample; consequently, this device might be useful for X-ray crystallography. PMID:24121346

Shimizu, Nobutaka; Shimizu, Tetsuya; Baba, Seiki; Hasegawa, Kazuya; Yamamoto, Masaki; Kumasaka, Takashi

2013-10-02

37

Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer  

NASA Astrophysics Data System (ADS)

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.

2007-04-01

38

Monitoring of slaughterhouse wastewater biodegradation in a SBR using fluorescence and UV-Visible absorbance.  

PubMed

The aim of this study was to demonstrate that the effectiveness of slaughterhouse wastewater treatment by activated sludge could be enhanced through the use of optical techniques, such as UV-Visible absorbance and fluorescence spectroscopy, to estimate the hydraulic retention time necessary to remove the biodegradable chemical oxygen demand (COD). Two experiments were conducted. First, a batch aerobic degradation was performed on four wastewater samples collected from four different cattle processing sites in order to study the changes in the spectroscopic properties of wastewater during biodegradation. Second, a sequencing batch reactor was used in order to confirm that the wastewater fluorescence could be successfully used to monitor wastewater biodegradation in a pilot-scale experiment. Residual blood was the main source of organic matter in the wastewater samples. The absorbance at 416 nm, related to porphyrins, was correlated to the COD during wastewater biodegradation. The tryptophan-like/fulvic-like fluorescence intensity ratio was related to the extent of biodegradation. The COD removal efficiency ranged from 74% to 94% with an hydraulic retention time (HRT) of 23 h. A ratio of tryptophan-like/fulvic-like fluorescence intensities higher than 1.2 indicated incomplete biodegradation of the wastewater and the need to increase the HRT. PMID:23402921

Louvet, J N; Homeky, B; Casellas, M; Pons, M N; Dagot, C

2013-02-10

39

Validation of GOMOS vertical profiles using the stratospheric balloon-borne AMON and SALOMON UV-Visible spectrometers  

Microsoft Academic Search

The stratospheric balloon-borne UV-visible spectrometers AMON and SALOMON, which uses stars and Moon as light source, respectively, were involved in the validation of the UV-visible spectrometer GOMOS onboard ENVISAT, which uses also stars as light source. A low spectral resolution UV-visible spectrometer, AMON-RA, is also implanted in the AMON gondola, for the validation of the GOMOS algorithm dedicated to the

J. B. Renard; M. Chartier; G. Berthet; C. Robert; T. Lemaire; F. Pepe; M. George; M. Pirre

2003-01-01

40

Measurement of carboxyhemoglobin in forensic blood samples using UV-visible spectrometry and improved principal component regression  

SciTech Connect

The forensic determination of carboxyhemoglobin (COHb) in blood was performed by using an improved principal component regression (PCR) technique applied to UV-visible spectra. Calibration data were decomposed into principal components, and the principal components useful for prediction were selected by their correlation with calibration spectra. Cross-validation of prediction results was done by leverage-corrected residuals. Confidence and prediction intervals derived from classical regression theory were found to be reasonable in size. The results compared favorably to a comparison study conducted by using a CO Oximeter method. In analysis of forensic case study samples, the improved PCR method allowed detection of abnormal samples and successfully predicted percentages of COHb and methemoglobin (MetHb), and provided error estimates for those predictions. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}

Egan, William; Morgan, Stephen L. [Department of Chemistry and Biochemistry, The University of South Carolina, Columbia, South Carolina 29208 (United States)] Brewer, William E. [Toxicology Department, South Carolina Law Enforcement Division, 4416 Broad River Road, Columbia, South Carolina 29210 (United States)

1999-02-01

41

Quantitative Analysis by Derivative Electronic Spectroscopy  

Microsoft Academic Search

Absorption and emission spectroscopy in the ultraviolet and visible regions, apart from being the earliest physical techniques of analysis, have great utility in solving a variety of structural and analytical problems [l-41. However, in many cases the quantitative determination of individual components in a mixture by UV-VIS spectroscopy becomes very difficult owing to the spectral similarities and overlapping of weak

L. Dixit; S. Ram

1985-01-01

42

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...

43

Using a Fourier transform spectrometer for tropospheric UV-visible DOAS measurements  

Microsoft Academic Search

Concentration measurements of trace gases in the atmosphere require the use of highly sensitive and precise techniques. The UV-visible DOAS technique is one of them heavily used for tropospheric measurements. In order to assess the advantages and drawbacks of using a Fourier transform spectrometer, we have built a DOAS optical setup based on a Bruker IFS 120M spectrometer. The characteristics

Michel Carleer; Reginald Colin; Ann Carine Vandaele

1998-01-01

44

Ozone and nitrogen dioxide vertical distribution by uv-visible solar occultation from balloons  

Microsoft Academic Search

A light and easily handled balloon-borne uv-visible spectrometer was designed for investigating ozone photochemistry in the Arctic winter. The optical sonde was flown 10 times during the EASOE campaign at Kiruna in Northern Sweden from November 1991 until March 1992. The flights gave the first simultaneous measurements of the vertical distributions of ozone and nitrogen dioxide in the Arctic winter.

Jean-Pierre Pommereau; Jacques Piquard

1994-01-01

45

Ozone and nitrogen dioxide vertical distributions by UV-visible solar occultation from balloons  

Microsoft Academic Search

A light and easily handled balloon-borne uv-visible spectrometer was designed for investigating ozone photochemistry in the Arctic winter. The optical sonde was flown 10 times during the EASOE campaign at Kiruna in Northern Sweden from November 1991 until March 1992. The flights gave the first simultaneous measurements of the vertical distributions of ozone and nitrogen dioxide in the Arctic winter.

Jean-Pierre Pommereau; Jacques Piquard

1994-01-01

46

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...

47

Synchronous fluorescence, UV–visible spectrophotometric, and voltammetric studies of the competitive interaction of bis(1,10-phenanthroline)copper(II) complex and neutral red with DNA  

Microsoft Academic Search

Constant wavelength synchronous fluorescence spectroscopy (CW–SFS), UV–visible absorption spectroscopy, and cyclic and differential pulse voltammetry were applied to investigate the competitive interaction of DNA with the bis(1,10-phenanthroline)copper(II) complex cation ([Cu(phen)2]2+) and a fluorescence probe, neutral red dye (NR), in a tris–hydrogen chloride buffer (pH 7.4). The results show that both the [Cu(phen)2]2+and the NR molecules can intercalate competitively into the

Yongnian Ni; Daiqin Lin; Serge Kokot

2006-01-01

48

Multicomponent analyses of chiral samples by use of regression analysis of UV–visible spectra of cyclodextrin guest–host complexes  

Microsoft Academic Search

We report the first combined use of analytical spectroscopy, guest–host chemistry, and multivariate regression analysis for\\u000a determination of enantiometric composition of multicomponent samples of chiral analytes. Sample solutions containing multicomponent\\u000a analytes of ephedrine, tryptophan, propranolol, and proline of varying enantiomeric composition with beta-cyclodextrin (BCD)\\u000a or methyl-beta-cyclodextrin (Me-BCD) as chiral host molecules were investigated using ultraviolet (UV)–visible spectroscopy.\\u000a The interactions of

Sayo O. Fakayode; Pamlea N. Brady; David A. Pollard; Abdul K. Mohammed; Isiah M. Warner

2009-01-01

49

Time-dependent density functional theory simulation of UV/visible absorption spectra of zirconocene catalysts  

NASA Astrophysics Data System (ADS)

The UV/visible absorption spectra of rac-Et(Ind) 2ZrCl 2, rac-Et(Ind) 2ZrMeCl, rac-Et(Ind) 2Zr(Me) 2, and the [ rac-Et(Ind) 2ZrMe-C 2H 4] + complex, have been simulated by using the TDDFT technique within the adiabatic approximation and by using several basis sets and XC functionals. Hybrid XC functionals (B3LYP, B3P86 and mPW1PW91) turn out to reproduce fairly well the essential features of the experimental spectra which originate from ligand to metal charge transfer transitions. The comparison between the simulated and recorded UV/visible absorption spectra appears therefore as a promising technique for assigning the structure of reaction intermediates in zirconocene polymerization.

Cavillot, Valérie; Champagne, Beno??t

2002-03-01

50

Quantitative Analysis by Auger Electron Spectroscopy  

Microsoft Academic Search

A short review is presented of the theoretical background of a physical model for the quantification of Auger electron spectroscopy (AES) for surface analysis. The recent studies on the data-base for the inelastic mean free paths (IMFP) by Seah and Dench and systematic calculations of the backscattering factors (R) by Shimizu and Ichimura have now enabled standard quantitative corrections comparable

Ryuichi Shimizu

1983-01-01

51

Quantum computations of the UV–visible spectra of uric acid and its anions  

Microsoft Academic Search

UV–visible spectra of uric acid as a function of pH have been studied and compared with experimental data. Different quantum methodologies have been employed: CIS–ZINDO, CIS–HF and TD-DFT. Solvent effects were modeled using the COSMO model. To account for the change in maximum absorbance along a variation of pH, different forms of uric acid have been taken into account: uric

Muhannad Altarsha; Gérald Monard; Bertrand Castro

2006-01-01

52

In situ FTIR and UV-visible spectroelectrochemical studies of iron nitrosyl porphyrins in nonaqueous media  

Microsoft Academic Search

The techniques of in situ FTIR and UV-visible spectroelectrochemistry were combined with microvoltammetry in order to elucidate the prevailing mechanism for electrooxidation of (P)Fe(NO), where P is the dianion of tetraphenylporphyrin (TPP), meso-tetrakis(2,4,6-trimethylphenyl)porphyrin (TMP), or octaethylporphurin (OEP). Each metalloporphyrin undergoes three reversible oxidations at a Pt microelectrode of 25-μm diameter. These oxidations were examined with respect to the site of

X. H. Mu; K. M. Kadish

1988-01-01

53

Spectral Analysis in the UV-Visible Range for Revealing the Molecular Form of Combustion-Generated Carbonaceous Species  

Microsoft Academic Search

A method of UV-visible spectra analysis was developed for investigating the relationship between the optical properties and the complex composition\\/structure of carbonaceous species formed in a sooting premixed ethylene flame. The UV-visible spectra were measured on carbonaceous species, caught on quartz plates inserted along the flame and recovered by solvent treatment. The contribution and the structure of components in a

C. Russo; F. Stanzione; M. Alfè; A. Ciajolo; A. Tregrossi

2012-01-01

54

Structure and reactivity of thiazolium azo dyes: UV-visible, resonance Raman, NMR, and computational studies of the reaction mechanism in alkaline solution.  

PubMed

UV-visible absorption, resonance Raman, and (1)H NMR spectroscopy, allied with density functional theory (DFT) calculations, have been used to study the structure, bonding, and alkaline hydrolysis mechanism of the cationic thiazloium azo dye, 2-[2-[4-(diethylamino)phenyl]diazenyl]-3-methyl-thiazolium (1a), along with a series of six related dyes with different 4-dialkylamino groups and/or other phenyl ring substituents (2a-c, 3a-c) and the related isothiazolium azo dye, 5-[2-[4-(dimethylamino)phenyl]diazenyl]-2-methyl-isothiazolium (4). These diazahemicyanine dyes are calculated to have a similar low-energy structure that is cis, trans at the (iso)thiazolium-azo group, and for which the calculated Raman spectra provide a good match with the experimental data; the calculations on these structures are used to assign and discuss the transitions giving rise to the experimental spectra, and to consider the bonding and its variation between the dyes. UV-visible, Raman, and NMR spectra recorded from minutes to several weeks after raising the pH of an aqueous solution of 1a to ca. 11.5 show that the dominant initial step in the reaction is loss of diethylamine to produce a quinonimine (ca. hours), with subsequent reactions occurring on longer time scales (ca. days to weeks); kinetic analyses give a rate constant of 2.6 × 10(-2) dm(3) mol(-1) s(-1) for reaction of 1a with OH(-). UV-visible spectra recorded on raising the pH of the other dyes in solution show similar changes that are attributed to the same general reaction mechanism, but with different rate constants for which the dependence on structure is discussed. PMID:23427946

Abbott, Laurence C; Batchelor, Stephen N; Moore, John N

2013-02-21

55

UV-visible and infrared spectra of volatile uranyl complexes in the gas phase  

Microsoft Academic Search

The gas-phase UV-visible and infrared spectra of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)dioxouranium(VI) (UOâ(HFA)â) were found to exhibit a marked pressure and temperature dependence which appears consistent with the monomer-dimer equilibrium previously established for this compound. The visible spectra obtained for both the monomeric and dimeric species are unusual because the vibrational structure characteristic of the spectra of many uranyl compounds is completely absent. The

A. Ekstrom; H. J. Hurst; C. H. Randall; H. Loeh

1980-01-01

56

Absorption properties of synthetic Cr-doped spinels in the UV, visible and infrared range and their astronomical implications  

NASA Astrophysics Data System (ADS)

Among the oxides, spinels are relatively abundant constituents of stardust, as has been inferred from studies of presolar grains in meteorites. Up to now, only pure Mg Al-spinels have been considered as a possible stardust component. However, cosmically abundant transition metals such as iron or chromium may well be incorporated in spinels in the process of their formation in stellar atmospheres. We have produced synthetic Cr-doped spinels in order to study their UV, visible and IR spectra. Mass absorption coefficients (MACs) have been derived from transmission spectroscopy over a large wavelength range. For a Cr content of 5%, a maximum MAC in the UV (close to 200 nm) of 1000 cm2/g was found. For a Cr content of 10%, the maximum UV-MAC of spinel exceeds the maximum IR-MAC of 2000 cm2/g. The MIR bands of Cr-doped spinels are shifted to longer wavelengths with increasing Cr content, namely by ˜0.1 ?m per 5% Cr in the range covered by our measurements. We conclude that a Cr content of spinel amounting to a few percents (<10%) is compatible with astronomical observations of spinel-bearing dusty environments, while a larger chromium content of spinels is not consistent with the presently available astronomical data.

Richter, H.; Posch, T.; Taran, M. N.; Mutschke, H.

2005-11-01

57

The stability of aqueous nickel(II) chloride complexes in hydrothermal solutions: Results of UV-Visible spectroscopic experiments  

NASA Astrophysics Data System (ADS)

Knowledge of the thermodynamic properties of aqueous nickel chloride complexes is important for understanding and quantitatively evaluating nickel transport in hydrothermal systems. In this paper, UV-Visible spectroscopic measurements are reported for dissolved nickel in perchlorate, triflic acid and sodium chloride solutions at temperatures up to 250 °C and 100 bar. The observed molar absorbance of Ni2+ in both perchlorate and triflic acid solutions is similar, and the absorbance peak migrates toward lower energy (red-shift) with increasing temperature. The spectra of nickel chloride solutions show a systematic red-shift with increasing temperature and/or chloride concentration. This allowed identification of the nickel chloride species as NiCl+, NiCl2(aq) and NiCl3-, and determination of their formation constants. Based on the experimental data reported in this paper and those of previous experimental studies, formation constants for these nickel chloride complexes have been calculated for temperatures up to 700 °C and pressures up to 2000 bar. The solubility of millerite (NiS) and pentlandite (Ni4.5Fe4.5S8) calculated using these constants shows that nickel dissolves in significantly higher concentrations in hydrothermal solutions than previously estimated. However, the solubility is considerably lower than for corresponding cobalt sulphide minerals. This may explain why hydrothermal nickel deposits are encountered so much less frequently than hydrothermal deposits of cobalt.

Liu, Weihua; Migdisov, Artas; Williams-Jones, Anthony

2012-10-01

58

Quantitative NIR Spectroscopy of Massive Stars  

NASA Astrophysics Data System (ADS)

Interest for near-infrared (NIR) spectroscopy of massive stars has been dramatically increasing over the last decade. Because it allows one to observe objects inaccessible at optical wavelengths due to absorption, the infrared domain offers a privileged window to study highly extinguished objects. Yet, a detailed calibration of the massive star properties at NIR wavelength is still missing. Following the lines of the work of Repolust et al. (2005), we have acquired high resolution spectroscopy of several nearby massive stars using VLT/CRIRES, focusing on spectral lines of interest in the J, H, K, and L bands. In this work, we present the earliest results of our quantitative spectroscopic analysis of the main sequence stars in our sample. Using the unique combination of a genetic algorithm approach with the state-of-the-art non-LTE atmosphere model FASTWIND, we compare the stellar and wind properties as derived from the optical and the NIR regime.

Sana, H.; Stap, F. A.; de Koter, A.; Martins, F.; Smette, A.; De Becker, M.; Nazé, Y.

2012-12-01

59

Specific behavior of the p-aminothiophenol - Silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.  

PubMed

The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. PMID:24034220

Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

2013-08-22

60

Temperature-controlled release of catechol dye in thermosensitive phenylboronate-containing copolymers: A quantitative study  

Microsoft Academic Search

The reversible complex formation between two phenylboronic acid bearing copolymers and the catechol dye Alizarin Red S (ARS) was studied by dialysis experiments coupled with UV–visible spectroscopy. The first copolymer based on N-isopropylacrylamide (NIPAM) is thermosensitive, whereas the second one based on N,N-dimethylacrylamide (DMAM) is not. The investigation resulted in the quantitative determination of the host–guest binding constants at two

Gaëlle Carré de Lusançay; Sophie Norvez; Ilias Iliopoulos

2010-01-01

61

[Analysis of UV-visible absorption spectrum on the decolorization of industrial wastewater by disinfection].  

PubMed

The UV-Visible absorption spectrum of industrial wastewater was explored to introduce a substituting method determining the color of water, and to compare the decolorization efficacy of different disinfectants. The results show that the visible absorption spectrum(350-600 nm), instead of ultraviolet absorption spectrum, should be applied to characterize the color of wastewater. There is a good correlation between the features of visible absorption spectrum and the true color of wastewater. Both ozone and chlorine dioxide has a better decolorization performance than chlorine. However, the color of chlorine dioxide itself has a negative effect on decolorization. The changes in the features of visible absorption spectrum effectively reflect the variations in the color of wastewater after disinfection. PMID:23285878

Huang, Xin; Wang, Long-Yong; Gao, Nai-Yun; Li, Wei-Guo

2012-10-01

62

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

2012-03-30

63

Quantitative Photoacoustic Spectroscopy in the Frequency Domain  

NASA Astrophysics Data System (ADS)

In this paper, the development of a new methodology for the quantitative determination of the optical absorption coefficient in simple systems in which the light absorption follows Beer's law is described. An approximation of the heat diffusion model of the photoacoustic effect for thermally thick samples is explored. It was found that we could combine the amplitude and the phase of the photoacoustic signal to obtain a new analytical expression for the optical absorption coefficient. This expression is directly proportional to the normalized photoacoustic signal amplitude, the sine of the phase difference, and the heat capacity per unit of volume of the sample. The theoretical results were experimentally verified in the visible range (300 nm to 700 nm). The optical absorption coefficient obtained with this methodology was comparable to that obtained by UV-Vis spectroscopy.

Gutiérrez-Juárez, G.; Vela-Lira, H. A.; Yánez-Limón, J. M.; García-Rodríguez, F. J.; Polo-Parada, L.

2013-09-01

64

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...

65

Determination and resolution of non-UV–visible absorptive component during a kinetic process with modified soft modeling methods  

Microsoft Academic Search

Soft modeling (SM) methods can be used to resolve spectroscopic data from complicated reaction processes with unknown kinetics, with the exception of data containing a component for which there is no spectroscopic information available, such as an intermediate that does not absorb in the UV–visible region. In this work, modified SM methods were developed to resolve these undetectable components. Based

Qinghua Zhang; Xinwei Feng; Dejun Zhang; Yi Zhao; Zhongliang Zhu

2011-01-01

66

Quantitative imaging with electrical impedance spectroscopy.  

PubMed

Electrical impedance spectroscopy (EIS) is a noninvasive modality that can be used to determine the electrical admittivity inside a body given a discrete set of current/voltage measurements made on the surface. Of particular interest is the use of EIS in the diagnosis of breast cancer, as the admittivity spectra of malignant and benign tumors differ significantly. Due to the fact that x-ray mammography is the current standard method of breast imaging to detect tumors, it is natural to see if we can use the admittivity distribution along with the mammogram image to improve the diagnosis, with the hopes that the specificity of these two methods combined will be greatly improved from using the mammogram image on its own. EIS is a highly ill-posed inverse problem, but regularization, in the form of structural prior information from the mammogram image as well as modeling error, allows for the problem to be solved for in a computationally efficient manner with improved results. To interpret the solution from the EIS inverse problem, a classification scheme is added, providing a quantitative image which maps out the tissue classification of the inside of the breast. The computational methods for solving the EIS inverse problem and the classification scheme are discussed and computed examples are presented to demonstrate the high simulated sensitivity and specificity of the method. PMID:23079558

McGivney, Debra; Calvetti, Daniela; Somersalo, Erkki

2012-10-18

67

Quantitative atomic spectroscopy for primary thermometry  

SciTech Connect

Quantitative spectroscopy has been used to measure accurately the Doppler broadening of atomic transitions in {sup 85}Rb vapor. By using a conventional platinum resistance thermometer and the Doppler thermometry technique, we were able to determine k{sub B} with a relative uncertainty of 4.1x10{sup -4} and with a deviation of 2.7x10{sup -4} from the expected value. Our experiment, using an effusive vapor, departs significantly from other Doppler-broadened thermometry (DBT) techniques, which rely on weakly absorbing molecules in a diffusive regime. In these circumstances, very different systematic effects such as magnetic sensitivity and optical pumping are dominant. Using the model developed recently by Stace and Luiten, we estimate the perturbation due to optical pumping of the measured k{sub B} value was less than 4x10{sup -6}. The effects of optical pumping on atomic and molecular DBT experiments is mapped over a wide range of beam size and saturation intensity, indicating possible avenues for improvement. We also compare the line-broadening mechanisms, windows of operation and detection limits of some recent DBT experiments.

Truong, Gar-Wing; Luiten, Andre N. [Frequency Standards and Metrology Research Group, School of Physics, University of Western Australia, Perth, Western Australia 6009 (Australia); May, Eric F. [Centre for Energy, School of Mechanical and Chemical Engineering, University of Western Australia, Perth, Western Australia 6009 (Australia); Stace, Thomas M. [School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072 (Australia)

2011-03-15

68

UV visible spectral study on the stability of lead phthalocyanine complexes  

NASA Astrophysics Data System (ADS)

UV visible electronic spectral study has been done on lead phthalocyanine (PbPc), lead tetranitro phthalocyanine (PbTNP) and lead tetraamino phthalocyanine (PbTAP) in dimethyl sulphoxide (DMSO) and H2SO4 media. Metal free phthalocyanine (H2Pc) is insoluble in DMSO and soluble in conc. H2SO4. The study has been extended to H2Pc to compare the stability of phthalocyanine structure with the PbPc complexes in H2SO4 medium. PbPc complexes are stable in DMSO, and all the complexes are more stable in 36 N H2SO4 than in 30 N and 28 N H2SO4 media. Further, complete demetallation and degradation of the phthalocyanine structure have been observed for all the PbPc complexes in 36 N H2SO4 medium within a week's time. The stability of these complexes is compared with H2Pc in H2SO4 medium. The decomposition reactions in H2SO4 media for H2Pc, PbPc, PbTNP and PbTAP are followed spectrophotometrically and rate constants were calculated. The decomposition reactions were found to follow the first-order kinetics with respect to the concentration of their respective phthalocyanine derivatives.

Mohan Kumar, T. M.; Achar, B. N.

2006-11-01

69

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

NASA Astrophysics Data System (ADS)

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 and Raman activities have been computed. Potential energy distribution (PED) and normal mode analysis have also been performed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed and complete assignment of the observed spectra have been proposed. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and ?max were determined by time-dependent DFT (TD-DFT) method. The geometrical, thermodynamical parameters and absorption wavelengths were compared with the experimental data. The interactions of carbonyl and hydrazide groups on the benzene ring skeletal modes were investigated.

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

2011-08-01

70

Development of a nondispersive UV-visible analyzer for simultaneous measurements of SO2 and NO2 in stacks emissions  

Microsoft Academic Search

12 Non-dispersive analyzers have been used for measurement of gases for many years and were recently introduced as on-line meters for continuous stack emission measurements in industrial plants. SO2 and NO2 are among the most important gases in the emissions of the petrochemical industry. The development of a UV-visible meter for these gases is presented. It consists of three optical

Daniel C. Schinca; Gustavo Ratto; Fabian Videla; Edmundo Rodriguez; Roberto E. Di Paolo; Jorge O. Tocho

2001-01-01

71

NDACC UV-visible total ozone measurements: improved retrieval and comparison with correlative satellite and ground-based observations  

Microsoft Academic Search

Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers.

F. Hendrick; J.-P. Pommereau; F. Goutail; R. D. Evans; D. Ionov; A. Pazmino; E. Kyrö; G. Held; P. Eriksen; V. Dorokhov; M. Gil; M. van Roozendael

2010-01-01

72

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

73

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

74

Quantitative photoacoustic spectroscopy of cataractous human lenses.  

PubMed

Quantitative photoacoustic spectra of the nuclei of cataractous human lenses with various degrees of colouration and opacification were measured in the spectral range 250-600 nm. The lens nuclei were obtained from 20 cataractous patients through extracapsular cataract extraction. These measurements yield the light loss per unit path length in the nucleus of cataractous lenses. PMID:2111385

Bernini, U; Reccia, R; Russo, P; Scala, A

1990-03-01

75

Retrieval of Stratospheric O3 and NO2 Density Profiles From a DOAS Analysis of UV-Visible Limb Scatter Measured by OSIRIS  

NASA Astrophysics Data System (ADS)

Space-based atmospheric remote sounding measurements of minor species in the stratosphere using UV-visible radiances have traditionally been of two types: occultation measurements (POAM, SAGE) and nadir measurements (TOMS, GOME). These types of measurements are limited by either restricted spatial coverage (occultation) or poor vertical resolution (nadir). A new type of measurement, with the potential of providing both good spatial coverage and good vertical resolution, is limb scattered sunlight. This type of measurement has been used to recover O3 in the mesosphere and NO2 in the stratosphere from SME measurements and recently has been used to retrieve stratospheric ozone density profiles from SOLSE/LORE measurements. A number of new instruments are employing this method, including OSIRIS, onboard the recently launched Odin satellite, and SCIAMACHY, which will be launched on ENVISAT in late 2001. Though the measurements themselves are relatively straightforward to make, the process of retrieving minor species densities and other information from the radiances is complicated due to the viewing geometry. A method that has proved successful for analysing UV-visible measurements made with ground-based instruments and with satellite nadir-viewing instruments has been that of Differential Optical Absorption Spectroscopy (DOAS). With the DOAS method absorption features are used to recover slant column densities which are then converted to vertical column densities through calculated air mass factors. Here we present the application of the DOAS method to limb scattered sunlight. In this application, apparent column densities are calculated through an analysis of measured limb radiances in a similar fashion as the calculation of the slant column densities in other applications. The complication here is that there is no straightforward relationship between these apparent column densities and the vertical column density. We describe how these apparent column densities, measured over a range of tangent heights, may be inverted using the Optimal Estimation (OE) approach to determine local density profiles, and apply the technique to the retrieval of stratospheric O3 and NO2 from OSIRIS measurements. Odin is a Swedish-led satellite project funded jointly by Sweden (SNSB), Canada (CSA), Finland (Tekes), and France (CNES).

Haley, C. S.; Sioris, C. E.; von Savigny, C.; McDade, I. C.; Griffioen, E.; McLinden, C. A.; Llewellyn, E. J.; ODIN Team

2001-12-01

76

UV/visible/near-infrared reflectance spectroscopic determination of cotton fiber and trash content in lint cotton waste  

NASA Astrophysics Data System (ADS)

Lint cleaning at cotton processing facilities is performed in order to remove the non-lint materials with minimal fiber damage. The resultant waste contains some degree of cotton fiber having good equal qualities, and hence is of great concern for operating cost. Traditional methods for measuring non-lint trash are labor intensive and time consuming. UV / visible / NIR technique was examined for its feasibility in determining the portions of cotton fiber and trash. Overall result indicated that NIR prediction was limited to screening purpose for probable reasons as heterogeneous trash distribution, relatively small sampling, and gravimetric reference method.

Liu, Yongliang; Gamble, Gary R.; Thibodeaux, Devron

2010-04-01

77

Quantitative Determination of Dielectric Thin-Film Properties Using Infrared Emission Spectroscopy;Applied Spectroscopy.  

National Technical Information Service (NTIS)

We have completed an experimental study to investigate the use of infrared emission spectroscopy (IRES) for the quantitative analysis of borophosphosilicate glass (BPSG) thin films on silicon monitor wafers. Experimental parameters investigated included t...

J. E. Franke D. M. Haaland T. M. Niemczyk S. Zhang

1998-01-01

78

Basic Principles of Spectroscopy  

NASA Astrophysics Data System (ADS)

Spectroscopy deals with the production, measurement, and interpretation of spectra arising from the interaction of electromagnetic radiation with matter. There are many different spectroscopic methods available for solving a wide range of analytical problems. The methods differ with respect to the species to be analyzed (such as molecular or atomic spectroscopy), the type of radiation-matter interaction to be monitored (such as absorption, emission, or diffraction), and the region of the electromagnetic spectrum used in the analysis. Spectroscopic methods are very informative and widely used for both quantitative and qualitative analyses. Spectroscopic methods based on the absorption or emission of radiation in the ultraviolet (UV), visible (Vis), infrared (IR), and radio (nuclear magnetic resonance, NMR) frequency ranges are most commonly encountered in traditional food analysis laboratories. Each of these methods is distinct in that it monitors different types of molecular or atomic transitions. The basis of these transitions is explained in the following sections.

Penner, Michael H.

79

The Infrared and UV-Visible Spectra of Polycyclic Aromatic Hydrocarbons Containing (5, 7)-Member Ring Defects: A Theoretical Study  

NASA Astrophysics Data System (ADS)

We report a theoretical investigation of the infrared (IR) spectra of polycyclic aromatic hydrocarbons (PAHs) containing (5, 7)-member ring defects based on a C48H18 model. Calculations are mostly performed using the hybrid B3LYP density functional theory (DFT) with a 6-31G(d) or 4-31G basis set. The results show that the Stone-Wales defect in PAHs can yield a strong IR band at 1448 cm-1 and a weak band at 611 cm-1, which may contribute to the UIR (unidentified infrared) bands at 6.9 ?m and 16.4 ?m observed in the interstellar medium. The charge effect on the IR spectra is discussed. The stability of the ring defected PAHs is also addressed by exploring the minimum energy pathway on the potential energy surface and through their UV-visible spectra, which are computed using a TDDFT method.

Yu, Hua-Gen; Nyman, Gunnar

2012-05-01

80

High-performance UV-visible-NIR broad spectral photodetectors based on one-dimensional In?Te? nanostructures.  

PubMed

For the first time, high quality In(2)Te(3) nanowires were synthesized via a chemical vapor deposition (CVD) method. The synthesized In(2)Te(3) nanowires are single crystals grown along the [132] direction with a uniform diameter of around 150 nm and an average length of tens of micrometers. Further, two kinds of photodetectors made by 1D In(2)Te(3) nanostructures synthesized by CVD and solvothermal (ST) methods respectively were fabricated. To our best knowledge, this is the first time photoresponse properties of In(2)Te(3) nanowire have been studied. The CVD grown nanowire device shows better performance than the ST device, which demonstrates a fast, reversible, and stable photoresponse and also a broad light detection range from 350 nm to 1090 nm, covering the UV-visible-NIR region. The excellent performance of the In(2)Te(3) nanowire photodetectors will enable significant advancements of the next-generation photodetection and photosensing applications. PMID:22908854

Wang, Zhenxing; Safdar, Muhammad; Jiang, Chao; He, Jun

2012-08-23

81

Quantitative and Rapid DNA Detection by Laser Transmission Spectroscopy  

PubMed Central

Laser transmission spectroscopy (LTS) is a quantitative and rapid in vitro technique for measuring the size, shape, and number of nanoparticles in suspension. Here we report on the application of LTS as a novel detection method for species-specific DNA where the presence of one invasive species was differentiated from a closely related invasive sister species. The method employs carboxylated polystyrene nanoparticles functionalized with short DNA fragments that are complimentary to a specific target DNA sequence. In solution, the DNA strands containing targets bind to the tags resulting in a sizable increase in the nanoparticle diameter, which is rapidly and quantitatively measured using LTS. DNA strands that do not contain the target sequence do not bind and produce no size change of the carboxylated beads. The results show that LTS has the potential to become a quantitative and rapid DNA detection method suitable for many real-world applications.

Li, Frank; Mahon, Andrew R.; Barnes, Matthew A.; Feder, Jeffery; Lodge, David M.; Hwang, Ching-Ting; Schafer, Robert; Ruggiero, Steven T.; Tanner, Carol E.

2011-01-01

82

De novo design of chiral organotin cancer drug candidates: validation of enantiopreferential binding to molecular target DNA and 5'-GMP by UV-visible, fluorescence, (1)H and (31)P NMR.  

PubMed

N,N-bis[(R-/S-)-1-benzyl-2-ethoxyethane] tin (IV) complexes were synthesized by applying de novo design strategy by the condensation reaction of (R-/S-)2-amino-2-phenylethanol and dibromoethane in presence of dimethyltin dichloride and thoroughly characterized by elemental analysis, conductivity measurements, IR, ESI-MS, (1)H, (13)C and (119)Sn, multinuclear NMR spectroscopy and XRD study. Enantioselective and specific binding profile of R-enantiomer 1 in comparison to S-enantiomer 2 with ultimate molecular target CT-DNA was validated by UV-visible, fluorescence, circular dichroism, (1)H and (31)P NMR techniques. This was further corroborated well by interaction of 1 and 2 with 5'-GMP. PMID:21945056

Arjmand, Farukh; Sharma, Girish Chandra; Sayeed, Fatima; Muddassir, Mohd; Tabassum, Sartaj

2011-08-26

83

[Study on UV-visible DOAS system based on photodiode array (PDA)].  

PubMed

A long-path differential optical absorption spectroscopy (DOAS) system is introduced. A photodiode array is employed as the detector to replace the complicated SD detector which consists of a PMT and a slotted disk. The properties of the detector and the spectrometer unit such as offset, dark current, noise, linearity, resolution, and wavelength range were measured. This system was also tested to measure SO2 and NO2 in the atmosphere. The detection limits of this system for SO2, and NO2 over a 713 m light path were determined. PMID:16379291

Qin, Min; Xie, Pin-hua; Liu, Jian-guo; Liu, Wen-qing; Fang, Wu; Lu, Fan; Li, Ang; Lu, Yi-huai; Wei, Qing-nong; Dou, Ke

2005-09-01

84

Retrieval of Stratospheric O3 and NO2 Density Profiles From a DOAS Analysis of UV-Visible Limb Scatter Measured by OSIRIS  

Microsoft Academic Search

Space-based atmospheric remote sounding measurements of minor species in the stratosphere using UV-visible radiances have traditionally been of two types: occultation measurements (POAM, SAGE) and nadir measurements (TOMS, GOME). These types of measurements are limited by either restricted spatial coverage (occultation) or poor vertical resolution (nadir). A new type of measurement, with the potential of providing both good spatial coverage

C. S. Haley; C. E. Sioris; C. von Savigny; I. C. McDade; E. Griffioen; C. A. McLinden; E. J. Llewellyn

2001-01-01

85

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

86

Aerosol Height Retrieval using UV-Visible Hyperspectral Satellite over East Asia  

NASA Astrophysics Data System (ADS)

From Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument, one of ground-based measurement, the vertical distribution of aerosol are estimated by the observed oxygen-dimer (O4) slant column densities (SCD) for several geometries (e.g., Hoenninger et al., 2004; Irie et al., 2009; Lee et al., 2011). Because the spatial and temporal variation of O4 distribution is little, the O4 SCD difference can be converted to the difference of optical path length. However, there have been very limited studies to date to retrieve aerosol height information by using satellite observation in UV wavelength range. This study investigates the sensitivities of aerosol height from the O4 SCDs using its absorption bands at 340, 360, 380, and 477 nm, where O4 SCD is calculated by the DOAS method using simulated spectra. From the experiment, robust relationship is obtained between the difference of O4 SCD and the aerosol height at 477 nm. Finally, the O4 SCD is converted to aerosol height by using the OMI observation for aerosol loaded cases, which is compared with ground-based lidar.

Park, Sang Seo; Kim, Jhoon; Lee, Hanlim

2013-04-01

87

Optical spectroscopy for quantitative sensing in human pancreatic tissues  

NASA Astrophysics Data System (ADS)

Pancreatic adenocarcinoma has a five-year survival rate of only 6%, largely because current diagnostic methods cannot reliably detect the disease in its early stages. Reflectance and fluorescence spectroscopies have the potential to provide quantitative, minimally-invasive means of distinguishing pancreatic adenocarcinoma from normal pancreatic tissue and chronic pancreatitis. The first collection of wavelength-resolved reflectance and fluorescence spectra and time-resolved fluorescence decay curves from human pancreatic tissues was acquired with clinically-compatible instrumentation. Mathematical models of reflectance and fluorescence extracted parameters related to tissue morphology and biochemistry that were statistically significant for distinguishing between pancreatic tissue types. These results suggest that optical spectroscopy has the potential to detect pancreatic disease in a clinical setting.

Wilson, Robert H.; Chandra, Malavika; Lloyd, William; Chen, Leng-Chun; Scheiman, James; Simeone, Diane; McKenna, Barbara; Mycek, Mary-Ann

2011-06-01

88

Quantitative Raman Spectroscopy of Biomaterials for Arthroplastic Applications  

NASA Astrophysics Data System (ADS)

Raman microprobe spectroscopy has considerable potential as an analytical tool in orthopedic science for its capability of non-destructively assessing the physical, chemical, and mechanical characteristics of load-bearing parts in arthroplastic components (i.e., artificial joints). In comparison to other assessment techniques, Raman spectroscopy offers high spatial resolution in the characterization of oxidation states, phase transformations, crystallographic textures, and residual stress/strain fields as developed at load-bearing surfaces of arthroplastic components, when embedded in biological environment. Furthermore, confocal probes can be used for non-destructively determining highly graded properties along the material subsurface. We show in this chapter a quantitative visualization of biomaterial mesostructures and, through such information, how the surfaces of orthopedic prostheses react to load bearing in biological environment.

Pezzotti, Giuseppe

89

Quantitative analysis of gallstones using laser-induced breakdown spectroscopy  

SciTech Connect

The utility of laser-induced breakdown spectroscopy (LIBS) for categorizing different types of gallbladder stone has been demonstrated by analyzing their major and minor constituents. LIBS spectra of three types of gallstone have been recorded in the 200-900 nm spectral region. Calcium is found to be the major element in all types of gallbladder stone. The spectrophotometric method has been used to classify the stones. A calibration-free LIBS method has been used for the quantitative analysis of metal elements, and the results have been compared with those obtained from inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements. The single-shot LIBS spectra from different points on the cross section (in steps of 0.5 mm from one end to the other) of gallstones have also been recorded to study the variation of constituents from the center to the surface. The presence of different metal elements and their possible role in gallstone formation is discussed.

Singh, Vivek K.; Singh, Vinita; Rai, Awadhesh K.; Thakur, Surya N.; Rai, Pradeep K.; Singh, Jagdish P

2008-11-01

90

Toward Quantitative "In Vivo Biochemistry" with Fluorescence Fluctuation Spectroscopy  

PubMed Central

Quantitative description of protein dynamics and interactions in vivo with temporal and spatial resolution is a key step in dissecting molecular mechanisms in cell biology. Fluorescence fluctuation spectroscopy (FFS) has recently emerged as a powerful in vivo tool for assessing molecular concentration and movement and formation of hetero- and homo-oligomeric complexes. This article discusses point FFS-based analysis methods that have proven useful to cell biologists, focusing on the kinds of information they provide, their pros and cons, and the basic instrumentation required. Along the way, we describe briefly a few recent examples where these analyses have helped address important biological questions.

2010-01-01

91

Capillary electrophoresis, mass spectrometry, and UV-visible absorption studies on electrolyte-induced fractionation of gold nanoclusters.  

PubMed

We describe a novel and simple electrolyte-induced fractionation method to separate a polydisperse water-soluble gold nanocluster (Au NC) product. Different particle sizes of Au NC fractions can be easily centrifuged down as a function of the electrolyte concentration or lipophilicity of the solution. The changes in the absorption characteristic of the Au NC fractions under different electrolyte/ethanol conditions demonstrate the change in particle size distribution of the Au NC. Small gold nanoclusters, Au10, Au11, Au12, and Au15, were separated from the Au10-Au50 polydisperse Au NC product under various phosphate/ethanol conditions. The core size separation of Au NC was evaluated by their migration trends in capillary zone electrophoresis, UV-visible absorption, and mass spectra. The electrolyte-induced fractionation not only provides a convenient method to separate small Au NC mixture but also assists in the study of the photophysical properties of smaller Au NCs that are present with the larger Au NCs in a polydisperse Au NC product. PMID:18324792

Lo, Chung Keung; Paau, Man Chin; Xiao, Dan; Choi, Martin M F

2008-03-07

92

UV-visible spectroscopic estimation of photodegradation of rhodamine-B dye using tin(IV) oxide nanoparticles.  

PubMed

Nanocrystalline, tin(IV) oxide (SnO(2)) particles has been prepared by thermal decomposition of tin oxalate precursor obtained from the reactions of tin(IV) chloride and sodium oxalate using eggshell membrane (ESM). The as-prepared SnO(2) nanoparticles were characterized by thermal studies, transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Raman, FT-IR and UV-visible studies and used as a photocatalyst for the degradation of rhodamine-B (Rh-B) dye. The size of the prepared nanoparticles was in the range of 5-12nm as identified from the TEM images. Powder XRD data revealed the presence of a tetragonal, rutile crystalline phase of the tin(IV) oxide nanoparticles. Thermal analysis showed that the decomposition of tin oxalate precursor to yield the titled tin(IV) oxide nanoparticles was completed below 500°C. The extent of degradation of Rh-B in the presence of SnO(2) monitored by absorption spectral measurements demonstrated that 94.48% of the selected dye was degraded upon irradiation with UV light for 60 min. PMID:22902583

Sangami, G; Dharmaraj, N

2012-07-25

93

UV-visible spectroscopic estimation of photodegradation of rhodamine-B dye using tin(IV) oxide nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocrystalline, tin(IV) oxide (SnO2) particles has been prepared by thermal decomposition of tin oxalate precursor obtained from the reactions of tin(IV) chloride and sodium oxalate using eggshell membrane (ESM). The as-prepared SnO2 nanoparticles were characterized by thermal studies, transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Raman, FT-IR and UV-visible studies and used as a photocatalyst for the degradation of rhodamine-B (Rh-B) dye. The size of the prepared nanoparticles was in the range of 5-12 nm as identified from the TEM images. Powder XRD data revealed the presence of a tetragonal, rutile crystalline phase of the tin(IV) oxide nanoparticles. Thermal analysis showed that the decomposition of tin oxalate precursor to yield the titled tin(IV) oxide nanoparticles was completed below 500 °C. The extent of degradation of Rh-B in the presence of SnO2 monitored by absorption spectral measurements demonstrated that 94.48% of the selected dye was degraded upon irradiation with UV light for 60 min.

Sangami, G.; Dharmaraj, N.

2012-11-01

94

THE INFRARED AND UV-VISIBLE SPECTRA OF POLYCYCLIC AROMATIC HYDROCARBONS CONTAINING (5, 7)-MEMBER RING DEFECTS: A THEORETICAL STUDY  

SciTech Connect

We report a theoretical investigation of the infrared (IR) spectra of polycyclic aromatic hydrocarbons (PAHs) containing (5, 7)-member ring defects based on a C{sub 48}H{sub 18} model. Calculations are mostly performed using the hybrid B3LYP density functional theory (DFT) with a 6-31G(d) or 4-31G basis set. The results show that the Stone-Wales defect in PAHs can yield a strong IR band at 1448 cm{sup -1} and a weak band at 611 cm{sup -1}, which may contribute to the UIR (unidentified infrared) bands at 6.9 {mu}m and 16.4 {mu}m observed in the interstellar medium. The charge effect on the IR spectra is discussed. The stability of the ring defected PAHs is also addressed by exploring the minimum energy pathway on the potential energy surface and through their UV-visible spectra, which are computed using a TDDFT method.

Yu Huagen; Nyman, Gunnar, E-mail: hgy@bnl.gov, E-mail: nyman@chem.gu.se [Department of Chemistry and Molecular Biology, Physical Chemistry, University of Gothenburg, SE-412 96 Gothenburg (Sweden)

2012-05-20

95

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

2012-08-20

96

Quantitative spectroscopy analysis of prokaryotic cells: vegetative cells and spores.  

PubMed

Multiwavelength ultraviolet/visible (UV-Vis) spectra of microorganisms and cell suspensions contain quantitative information on properties such as number, size, shape, chemical composition, and internal structure of the suspended particles. These properties are essential for the identification and classification of microorganisms and cells. The complexity of microorganisms in terms of their chemical composition and internal structure make the interpretation of their spectral signature a difficult task. In this paper, a model is proposed for the quantitative interpretation of spectral patterns resulting from transmission measurements of prokaryotic microorganism suspensions. It is also demonstrated that different organisms give rise to spectral differences that may be used for their identification and classification. The proposed interpretation model is based on light scattering theory, spectral deconvolution techniques, and on the approximation of the frequency dependent optical properties of the basic constituents of living organisms. The quantitative deconvolution in terms of the interpretation model yields critical information necessary for the detection and identification of microorganisms, such as size, dry mass, dipicolinic acid concentration, nucleotide concentration, and an average representation of the internal scattering elements of the organisms. E. coli, P. agglomerans, B. subtilis spores, and vegetative cells and spores of Bacillus globigii are used as case studies. It is concluded that spectroscopy techniques coupled with effective interpretation models are applicable to a wide range of cell types found in diverse environments. PMID:15128109

Alupoaei, Catalina E; Olivares, Jose A; García-Rubio, Luis H

2004-03-15

97

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study  

Microsoft Academic Search

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses

H. A. Elbatal; A. M. Abdelghany; F. H. Elbatal; Kh. M. Elbadry; F. A. Moustaffa

2011-01-01

98

UV–visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study  

Microsoft Academic Search

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV–visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses

H. A. ElBatal; A. M. Abdelghany; F. H. ElBatal; Kh. M. ElBadry; F. A. Moustaffa

2011-01-01

99

Calculating iron contents of lunar highland materials surrounding Tycho crater from integrated Clementine UV-visible and near-infrared data  

NASA Astrophysics Data System (ADS)

Optical properties of lunar surface materials are modified by exposure to the space environment, including bombardment by solar wind particles and micrometeorites. One of the main problems in the interpretation of lunar spectral observations is to separate the effects of exposure (``space weathering'') and those due to the composition of the soils (mainly iron and titanium content). Here we use Clementine near-infrared (NIR) data to investigate this problem for highland-type soils in the Tycho crater area. Our approach is based on the methods developed for an analysis of a mare region near Aristarchus Plateau [Le Mouélic et al., 2000]. We show that the systematic relationships between spectral parameters (1-?m band depth and continuum slope), which were previously observed in a mare area with varying maturity degree, are also valid for highland-type soils. This technique aimed at evaluating the iron content of the surface materials from Clementine UV-visible (UVVIS) and near-infrared data can therefore be applied globally. This approach complements the widely used method of Lucey and coworkers, which relies on the UV-visible bands only. The proposed method relies mostly on band ratios. The iron map produced from this method is therefore less dependent on topography than the iron estimates obtained with UV-visible data alone, where brightness is one of the controlling parameters. Therefore the proposed approach should be particularly useful at middle to high latitudes, where local topography generates large variations in brightness and therefore hampers the interpretation of iron maps produced from UV-visible bands only.

Le Mouélic, Stéphane; Lucey, P. G.; Langevin, Yves; Hawke, B. Ray

2002-10-01

100

NDACC\\/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative ground-based and satellite observations  

Microsoft Academic Search

Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers.

F. Hendrick; J.-P. Pommereau; F. Goutail; R. D. Evans; D. Ionov; A. Pazmino; E. Kyrö; G. Held; P. Eriksen; V. Dorokhov; M. Gil; M. van Roozendael

2011-01-01

101

Retrieval of nitrogen dioxide stratospheric profiles from ground-based zenith-sky UV-visible observations: validation of the technique through correlative comparisons  

Microsoft Academic Search

A retrieval algorithm based on the Optimal Estimation Method (OEM) has been developed in order to provide vertical distributions of NO2 in the stratosphere from ground-based (GB) zenith-sky UV-visible observations. It has been applied to observational data sets from the NDSC (Network for Detection of Stratospheric Change) stations of Harestua (60° N, 10° E) and Andøya (69° N, 16° E)

F. Hendrick; B. Barret; M. van Roozendael; H. Boesch; A. Butz; M. de Mazière; F. Goutail; C. Hermans; J.-C. Lambert; K. Pfeilsticker; J.-P. Pommereau

2004-01-01

102

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

103

A new tridentate Schiff base Cu(II) complex: synthesis, experimental and theoretical studies on its crystal structure, FT-IR and UV-Visible spectra.  

PubMed

A new Cu(II) complex [Cu(L)(NCS)] has been synthesized, using 1-(N-salicylideneimino)-2-(N,N-methyl)-aminoethane as tridentate ONN donor Schiff base ligand (HL). The dark green crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FT-IR) and UV-Visible spectra. Electronic structure calculations at the B3LYP and MP2 levels of theory are performed to optimize the molecular geometry and to calculate the UV-Visible and FT-IR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TD-DFT) method is used to calculate the electronic transitions of the complex. A scaling factor of 1.015 is obtained for vibrational frequencies computed at the B3LYP level using basis sets 6-311G(d,p). It is found that solvent has a profound effect on the electronic absorption spectrum. The UV-Visible spectrum of the complex recorded in DMSO and DMF solution can be correctly predicted by a model in which DMSO and DMF molecules are coordinated to the central Cu atom via their oxygen atoms. PMID:23562742

Saheb, Vahid; Sheikhshoaie, Iran; Setoodeh, Nasim; Rudbari, Hadi Amiri; Bruno, Giuseppe

2013-03-14

104

A new tridentate Schiff base Cu(II) complex: Synthesis, experimental and theoretical studies on its crystal structure, FT-IR and UV-Visible spectra  

NASA Astrophysics Data System (ADS)

A new Cu(II) complex [Cu(L)(NCS)] has been synthesized, using 1-(N-salicylideneimino)-2-(N,N-methyl)-aminoethane as tridentate ONN donor Schiff base ligand (HL). The dark green crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FT-IR) and UV-Visible spectra. Electronic structure calculations at the B3LYP and MP2 levels of theory are performed to optimize the molecular geometry and to calculate the UV-Visible and FT-IR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TD-DFT) method is used to calculate the electronic transitions of the complex. A scaling factor of 1.015 is obtained for vibrational frequencies computed at the B3LYP level using basis sets 6-311G(d,p). It is found that solvent has a profound effect on the electronic absorption spectrum. The UV-Visible spectrum of the complex recorded in DMSO and DMF solution can be correctly predicted by a model in which DMSO and DMF molecules are coordinated to the central Cu atom via their oxygen atoms.

Saheb, Vahid; Sheikhshoaie, Iran; Setoodeh, Nasim; Rudbari, Hadi Amiri; Bruno, Giuseppe

2013-06-01

105

Methodologies for laboratory Laser Induced Breakdown Spectroscopy semi-quantitative and quantitative analysis—A review  

NASA Astrophysics Data System (ADS)

Since its early applications, Laser Induced Breakdown Spectroscopy has been recognized as a useful tool for solid state chemical analysis. However the quantitative accuracy of the technique depends on the complex processes involved in laser induced plasma formation, ablation, atomization, excitation and ion recombination. Problems arising from laser target coupling, matrix effect, fractionation in target vaporization, local thermodynamic equilibrium assumption and interferences from additional air ionization should be properly addressed in order to obtain reliable quantitative results in laboratory to be used as starting point during field campaigns. As selected case studies carried out within the authors' research team show, a proper selection of laser parameters and, in general of experimental conditions, for laboratory data acquisition is required in order to minimize the mentioned problems both in case of calibration curves and calibration free approaches. In particular, the choice of reference samples for measuring calibration curves is of crucial importance in laboratory experiments, in relation both to matrix effect and local thermodynamic equilibrium, to be carried out at comparable conditions in terms of temperature and electron density. A model for the ablation process aimed to the optimization of experimental conditions in some case studies (copper alloys) has been specifically developed in order to account for the target stoichiometry in the plasma. Problems related to the limit of detection for quantitative trace analysis have been considered in analyzing data collected both inside and outside the local thermodynamic equilibrium window, in cases characterized by a fixed contamination threshold.

Fantoni, R.; Caneve, L.; Colao, F.; Fornarini, L.; Lazic, V.; Spizzichino, V.

2008-10-01

106

NDACC UV-visible total ozone measurements: improved retrieval and comparison with correlative satellite and ground-based observations  

NASA Astrophysics Data System (ADS)

Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers. These instruments, deployed all over the world in about 35 stations, allow measurements of total ozone twice daily with little sensitivity to stratospheric temperature and cloud cover. The NDACC recommendations address both the DOAS retrieval parameters and the calculation of air mass factors (AMF) needed for the conversion of O3 slant column densities into vertical column amounts. The most important improvement is the use of O3 AMF look-up tables calculated using the TOMS V8 O3 profile climatology, that allows accounting for the dependence of the O3 AMF on the seasonal and latitudinal variations of the O3 vertical distribution. To investigate their impact on the retrieved ozone columns, the recommendations have been applied to measurements from the NDACC/SAOZ (Système d'Analyse par Observation Zénithale) network. The revised SAOZ ozone data from eight stations covering all latitude regions have been compared to TOMS, GOME-GDP4, SCIAMACHY-TOSOMI, OMI-TOMS, and OMI-DOAS satellite overpass observations, as well as to those of collocated Dobson and Brewer instruments. A significant improvement is obtained after applying the new O3 AMFs, although systematic seasonal differences between SAOZ and all other instruments remain. These are shown to mainly originate from i) the temperature dependence of the ozone absorption cross sections in the UV being not or improperly corrected by some retrieval algorithms, and ii) the longitudinal differences in tropospheric ozone column being ignored by zonal climatologies. For those measurements sensitive to stratospheric temperature like TOMS, OMI-TOMS, Dobson and Brewer, the application of a temperature correction results in the almost complete removal of the seasonal difference with SAOZ, improving significantly the consistency between all ground-based and satellite total ozone observations.

Hendrick, F.; Pommereau, J.-P.; Goutail, F.; Evans, R. D.; Ionov, D.; Pazmino, A.; Kyrö, E.; Held, G.; Eriksen, P.; Dorokhov, V.; Gil, M.; van Roozendael, M.

2010-08-01

107

Electronic structure investigations of 4-methyl-3-penten-2-one by UV-Visible and NMR spectral studies and natural bond orbital analysis by DFT calculations  

NASA Astrophysics Data System (ADS)

Comprehensive theoretical and experimental UV-Visible, NMR spectroscopic studies of 4-methyl-3-penten-2-one (4M3P2O) have been carried out by using DFT/B3LYP method with 6-311++G\\midast\\midast and aug-cc-pVTZ basis sets. The most stable geometry of the compound has been determined from the PES scan. The temperature dependence of thermodynamic properties has been analysed. The atomic charges, electronic exchange interaction and charge delocalisation of the molecule have been performed by natural bond orbital (NBO) analysis. Molecular electrostatic surface potential, total electron density distribution and frontier molecular orbitals are constructed at B3LYP/6-311++G\\midast\\midast level to understand the electronic properties. The charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential. UV-Visible spectrum of the compound, the electronic properties, HOMO and LUMO energies were measured by time-dependent TD-DFT approach. 1H and 13C NMR spectra were recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were calculated in various solvents and in gas phase by using the Gauge-GIAO method.

Arjunan, V.; Jayaprakash, A.; Santhanam, R.; Thillai Govindaraja, S.; Mohan, S.

2012-08-01

108

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

109

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

110

Qualitative and quantitative analysis of wood samples by Fourier transform infrared spectroscopy and multivariate analysis  

Microsoft Academic Search

Fourier transform infrared (FTIR) spectroscopy, in combination with multivariate analysis, enable the analysis of wood samples without time-consuming sample preparation. The aim of our work was to analysis the wood samples qualitatively and quantitatively by FTIR spectroscopy. A Van Soest method to determine the lignin, cellulose and hemicellulose content, was used as reference method. Multivariate calibration was performed based on

Huilun Chen; Carlo Ferrari; Marco Angiuli; Jun Yao; Costantino Raspi; Emilia Bramanti

2010-01-01

111

Coded Aperture Raman Spectroscopy for Quantitative Measurements of Ethanol in a Tissue Phantom  

Microsoft Academic Search

Coded aperture spectroscopy allows for sources of large etendue to be efficiently coupled into dispersive spectrometers by replacing the traditional input slit with a patterned mask. We describe a coded aperture spectrometer optimized for Raman spectroscopy of diffuse sources, (e.g., tissue). We provide design details of the Raman system, along with quantitative estimation results for ethanol at non-toxic levels in

S. T. McCain; M. E. Gehm; Y. Wang; N. P. Pitsianis; D. J. Brady

2006-01-01

112

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

113

Quantitative Raman Spectroscopy of Biomaterials for Arthroplastic Applications  

Microsoft Academic Search

Raman microprobe spectroscopy has considerable potential as an analytical tool in orthopedic science for its capability of\\u000a non-destructively assessing the physical, chemical, and mechanical characteristics of load-bearing parts in arthroplastic\\u000a components (i.e., artificial joints). In comparison to other assessment techniques, Raman spectroscopy offers high spatial\\u000a resolution in the characterization of oxidation states, phase transformations, crystallographic textures, and residual stress\\/strain\\u000a fields

Giuseppe Pezzotti

114

Quantitative Infrared Spectroscopy of Minor Constituents of the Earth's Atmosphere.  

National Technical Information Service (NTIS)

We obtain quantitative laboratory spectroscopic measurements of molecular constituents which are of importance in understanding the health of the Earth's atmosphere, and, in particular, emphasize those species which are important for understanding stratos...

C. Chackerian L. P. Giver D. Goorvitch M. Spencer F. P. J. Valero

1990-01-01

115

UV-visible absorption of small gold clusters in neon: Au(n) (n = 1-5 and 7-9).  

PubMed

We present optical absorption spectra in the UV-visible range (1.5 eV < E < 6 eV) for mass selected neutral gold clusters Au(n) (n = 1-5 and 7-9) embedded in solid Ne at 7 K. The experimental spectra are compared with time-dependent density functional calculations. Electronic transitions are distributed over the whole energy range without any concentration of the oscillator strength in a small energy window, characteristic for the more s-like metals such as the alkalis or silver. Contrary to the case of silver and partly copper clusters, transitions issued from mainly d-type states are significantly involved in low energy transitions. The measured integrated cross section is smaller (<20%) than expected from a free-electron system, manifesting the strong screening of the s electrons due to the proximity of the s and d levels in gold. PMID:21341839

Lecoultre, S; Rydlo, A; Félix, C; Buttet, J; Gilb, S; Harbich, W

2011-02-21

116

Quantitative fractography of WC-Co cermets by Auger spectroscopy  

Microsoft Academic Search

A general procedure has been developed to determine the area fraction occupied by the binder on the fracture surfaces of cemented carbides. The area fraction of binder on the fracture surface was obtained from the relative peak-to-peak height ratios of elements in the binder and the carbide content was measured by Auger spectroscopy on the fracture surface and an adjacent

R. K. Viswanadham; T. S. Sun; E. F. Drake; J. A. Peck

1981-01-01

117

Photocatalytic Degradation of Organic Reactive Dyes over MnTiO3 /TiO2 Heterojunction Composites Under UV-Visible Irradiation.  

PubMed

In this study, the photocatalytic degradation of organic reactive dyes have been investigated using MnTiO3 /TiO2 heterojunction composites in the presence of electron acceptors under UV-Visible light irradiation. This MnTiO3 /TiO2 heterojunction composites were prepared by annealing different mass ratios of pyrophanite MnTiO3 (3-11 wt%) and TiO2 at 300°C. All the MnTiO3 /TiO2 heterojunction composites were characterized by spectral techniques like X-ray diffraction (XRD), scanning electron microscope (SEM) and diffused reflectance UV-visible spectroscopic analysis (DRS). Among them, 9 wt% MnTiO3 /TiO2 heterojunction composites exhibited higher photocatalytic activity for the degradation of Reactive Blue 4 (RB 4). The photocatalytic efficiency of 9 wt% MnTiO3 /TiO2 heterojunction composites was further enhanced by the addition of substantial amount of electron acceptors like hydrogen peroxide (H2 O2 ) and ammonium peroxydisulfate ([NH4 ]2 S2 O8 ). The presence of oxidants (electron acceptors) facilitates the fast degradation of dye solution even in higher concentration upto 200 mg/L. The photocatalytic activity of MnTiO3 /TiO2 heterojunction composites was also studied for the degradation of other four different structured reactive dyes. The extent of mineralization of these organic reactive dyes during photocatalytic degradation was estimated from COD analysis. MnTiO3 /TiO2 heterojunction composites was also found to have good photostability in the presence of oxidants. PMID:23848842

Sivakumar, Santhanam; Selvaraj, Ayyasamy; Ramasamy, Anaipalayam Kandasamy

2013-08-29

118

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

119

Quantitation of Edited GABA Signals in Magnetic Resonance Spectroscopy  

Microsoft Academic Search

Amino butyric acid (GABA) is an inhibitory neurotransmitter that plays an important role in several brain disorders. Reliable detection of GABA in vivo, us- ing 1H Magnetic Resonance Spectroscopy is difficult and faces various challenges. Spectral-Editing sequences based on multiple quantum filtering techniques enable remov- ing overlapping signals. However, advanced signal pro- cessing accommodating sequence-dependence of the edited signals are

B. Tchong Len; H. Ratiney; C. Cudalbu; B. Fenet; A. R. Allouche; M. Aubert-Frecon; D. van Ormondt; D. Graveron-Demilly

120

Quantitative proton magnetic resonance spectroscopy of the cervical spinal cord.  

PubMed

Proton MR spectroscopy ((1)H-MRS) provides indices of neuronal damage in the central nervous system (CNS); however, it has not been extensively applied in the spinal cord. This work describes an optimized proton spectroscopy protocol for examination of the human cervical spinal cord. B(0) field mapping of the cord revealed periodic inhomogeneities due to susceptibility differences with surrounding tissue. By combining field maps and experimental data, we found that the optimum voxel size was 9 x 7 x 35 mm(3) placed with the inferior end of the voxel above vertebral body C2. Metabolite concentrations were determined in the cervical cord in six healthy controls by short-echo point-resolved spectroscopy (PRESS) volume localization. The results were compared with metabolite concentrations in the brainstem, cerebellum, and cortex in the same individuals. The concentrations in the cervical cord were as follows: N-acetyl-aspartate (NAA) 17.3 +/- 0.5, creatine (Cr) 9.5 +/- 0.9, and choline 2.7 +/- 0.5 mmol/l. The NAA concentration was significantly lower in the cord than in the brainstem (Mann-Whitney, P < 0.025), and higher than in the cortex (P < 0.005) and cerebellum (P < 0.005). Cr was significantly lower in the cord than in the cerebellum (P < 0.05). There were no significant differences between Cr concentrations in the spinal cord compared to the cortex and brainstem. PMID:15170831

Cooke, F J; Blamire, A M; Manners, D N; Styles, P; Rajagopalan, B

2004-06-01

121

Instrument independent diffuse reflectance spectroscopy  

PubMed Central

Diffuse reflectance spectroscopy with a fiber optic probe is a powerful tool for quantitative tissue characterization and disease diagnosis. Significant systematic errors can arise in the measured reflectance spectra and thus in the derived tissue physiological and morphological parameters due to real-time instrument fluctuations. We demonstrate a novel fiber optic probe with real-time, self-calibration capability that can be used for UV-visible diffuse reflectance spectroscopy in biological tissue in clinical settings. The probe is tested in a number of synthetic liquid phantoms over a wide range of tissue optical properties for significant variations in source intensity fluctuations caused by instrument warm up and day-to-day drift. While the accuracy for extraction of absorber concentrations is comparable to that achieved with the traditional calibration (with a reflectance standard), the accuracy for extraction of reduced scattering coefficients is significantly improved with the self-calibration probe compared to traditional calibration. This technology could be used to achieve instrument-independent diffuse reflectance spectroscopy in vivo and obviate the need for instrument warm up and post?premeasurement calibration, thus saving up to an hour of precious clinical time.

Yu, Bing; Fu, Henry L.; Ramanujam, Nirmala

2011-01-01

122

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

123

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

2013-03-11

124

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…

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

2008-01-01

125

Improved calculation of the backscattering factor for quantitative analysis by Auger electron spectroscopy  

Microsoft Academic Search

Based on a Monte Carlo simulation method, an improved calculation of the backscattering factor in quantitative analysis by Auger electron spectroscopy has been performed by integrating several aspects of recent progresses in the related fields. The calculation used a general definition of backscattering factor, more accurate ionization cross section, up-to-date Monte Carlo model of electron inelastic scattering, and a large

Z. J. Ding; W. S. Tan; Y. G. Li

2006-01-01

126

Quantitative Characterization of DNA Films by X-ray Photoelectron Spectroscopy.  

National Technical Information Service (NTIS)

We describe the use of self-assembled films of thiolated (dT)25 single-stranded DNA (ssDNA) on gold as a model system for quantitative characterization of DNA films by X-ray photoelectron spectroscopy (XPS). We evaluate the applicability of a uniform and ...

D. Y. Petrovykh H. Kimura-Suda L. J. Whitman M. J. Tarlov

2003-01-01

127

Inflammatory CNS Demyelination: Histopathologic Correlation with In Vivo Quantitative Proton MR Spectroscopy  

Microsoft Academic Search

BACKGROUND AND PURPOSE: The mechanisms behind the demyelination that is char- acteristic of multiple sclerosis (MS) are still poorly understood. The purpose of this study was to compare immunopathologic findings in demyelinating lesions of three patients with in vivo assessments obtained by quantitative proton MR spectroscopy (MRS). METHODS: Between four and seven stereotactic needle brain biopsies were performed in three

Andreas Bitsch; Harald Bruhn; Vassilios Vougioukas; Argyris Stringaris; Hans Lassmann; Jens Frahm; Wolfgang Bruck

1999-01-01

128

Rapid quantitative analysis of Dimethoate pesticide using surface enhanced raman spectroscopy  

Technology Transfer Automated Retrieval System (TEKTRAN)

A method for rapid quantitative detection of dimethoate pesticide by using surface-enhanced Raman spectroscopy (SERS) has been described. Significantly enhanced Raman signals of pesticide in low concentrations of 0.5 ~ 10 ug/mL were acquired by confocal raman micro-spectrometry with renishaw diagno...

129

Quantitative flash pyrolysis Fourier transform infrared spectroscopy of organic materials.  

PubMed

Thermal degradation is a common technique used to investigate the nature of organic materials. However, existing methods for the Fourier transform infrared (FTIR) identification and quantification of volatile products from the thermal degradation of organic materials are limited to the technique of thermogravimetric analysis (TGA)-FTIR, which utilizes relatively low heating rates. However, the thermal degradation products of organic materials are known to vary depending on the rate of heating, with lower heating rates of biomass associated with increased yields of solid char and decreased yields of volatiles, as well as a greater opportunity for secondary reactions between the residue and the pyrolysis products. Hence, it is difficult to relate the products of organic matter thermally degraded at <100 degrees C min(-1) in TGA to the products of flash pyrolysis at up to 20,000 degrees C s(-1). We have developed and applied a novel methodology for quantitative flash pyrolysis-FTIR analysis of the volatile pyrolysis products of organic-rich materials. Calibration curves of water, carbon dioxide and methane have been constructed and used to determine absolute volatile release from wood (ash, Lat. Fraxinus). This technique is quicker and simpler than comparable pyrolysis-gas chromatography-mass spectrometry techniques, and avoids errors associated with the lower rates of temperature increase associated with techniques such as thermogravimetric analysis. PMID:19345759

Court, Richard W; Sephton, Mark A

2009-03-06

130

Gas-Phase Database for Quantitative Infrared Spectroscopy  

SciTech Connect

The National Institute of Standards and Technology (NIST) and the Pacific Northwest National Laboratory (PNNL) are each creating quantitative databases containing the vapor-phase infrared spectra of pure chemicals. The digital databases have been created with both laboratory and remote-sensing applications in mind. A spectral resolution of {approx} 0.1 cm{sup -1} was selected to avoid degrading sharp spectral features, while also realizing that atmospheric broadening typically limits line widths to 0.1 cm{sup -1}. Calculated positional (wave number, cm{sup -1}) uncertainty is {le} 0.005 cm{sup -1}, while the 1{sigma} statistical uncertainty in absorbance values is <2% for most compounds. The latter was achieved by measuring multiple (typically {ge} 9) path length-concentration burdens and fitting a weighted Beer's law plot to each wave number channel. The two databases include different classes of compounds and were compared using 12 samples. Though these 12 samples span a range of polarities, absorption strengths, and vapor pressures, the data agree to within experimental uncertainties with only one exception.

Sharpe, Steven W.; Johnson, Timothy J.; Sams, Robert L.; Chu, Pamela M.; Rhoderick, G C.; Johnson, P A.

2004-12-10

131

Quantitative proton magnetic resonance spectroscopy without water suppression  

NASA Astrophysics Data System (ADS)

The suppression of the abundant water signal has been traditionally employed to decrease the dynamic range of the NMR signal in proton MRS (1H MRS) in vivo. When using this approach, if the intent is to utilize the water signal as an internal reference for the absolute quantification of metabolites, additional measurements are required for the acquisition of the water signal. This can be prohibitively time-consuming and is not desired clinically. Additionally, traditional water suppression can lead to metabolite alterations. This can be overcome by performing quantitative 1H MRS without water suppression. However, the non-water-suppressed spectra suffer from gradient-induced frequency modulations, resulting in sidebands in the spectrum. Sidebands may overlap with the metabolites, which renders the spectral analysis and quantification problematic. In this paper, we performed absolute quantification of metabolites without water suppression. Sidebands were removed by utilizing the phase of an external reference signal of single resonance to observe the time-varying the static field fluctuations induced by gradient-vibration and deconvolving this phase contamination from the desired NMR signal. The quantification of metabolites was determined after sideband correction by calibrating the metabolite signal intensities against the recorded water signal. The method was evaluated by phantom and in vivo measurements in human brain. The maximum systematic error for the quantified metabolite concentrations was found to be 10.8%, showing the feasibility of the quantification after sideband correction.

Özdemir, M. S.; DeDeene, Y.; Fieremans, E.; Lemahieu, I.

2009-06-01

132

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study  

NASA Astrophysics Data System (ADS)

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu2+ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.

Elbatal, H. A.; Abdelghany, A. M.; Elbatal, F. H.; Elbadry, Kh. M.; Moustaffa, F. A.

2011-10-01

133

Quantitative spectroscopy of photospheric-phase type II supernovae  

NASA Astrophysics Data System (ADS)

We present first results on the quantitative spectroscopic analysis of the photospheric-phase of type II supernovae (SN). The analyses are based on the model atmosphere code, CMFGEN, of Hillier & Miller (1998) which solves the radiative transfer and statistical equilibrium equations in expanding outflows under the constraint of radiative equilibrium. A key asset of CMFGEN is its thorough treatment of line-blanketing due to metal species. From its applicability to hot star environments, the main modifications to the source code were to allow a linear velocity law, a power-law density distribution, an adaptive grid to handle the steep H recombination/ionization front occurring in some SN models, and a routine to compute the gray temperature structure in the presence of large velocities. In this first paper we demonstrate the ability of CMFGEN to reproduce, with a high level of accuracy, the UV and optical observations of a sample of well observed type II SN, i.e. SN1987A and SN1999em, at representative stages of their photospheric evolution. Two principal stages of SN are modeled that where hydrogen is fully ionized, and that in which H is only partially ionized. For models with an effective temperature below ~8000 K, hydrogen recombines and gives rise to a steep ionization front. The effect of varying the location of the outer grid radius on the spectral energy distribution (SED) is investigated. We find that going to 5-6 times the optically-thick base radius is optimal, since above that, the model becomes prohibitively large, while below this, significant differences appear because of the reduced line-blanketing (which persists even far above the photosphere) and the truncation of line-formation regions. To constrain the metallicity and the reddening of SN, the UV spectral region of early-time spectra is essential. We find that the density of the photosphere and effect of line blanketing decline as the spatial scale of the SN increases. The density distribution is found to have a strong impact on the overall flux distribution as well as line profiles. For a given base density, the faster the density drops, the higher the effective temperature of the model. We also find in cool models that the set of Ca ii lines, near 8500 Å is strongly sensitive to the density gradient. They show a weaker and narrower profile for steeper density distributions. Hydrogen Balmer lines are very well reproduced in fully or partially ionized models, but underestimated when hydrogen recombines. A reduced turbulent velocity or a flatter density layout are found to partially, but not fully, cure this persistent problem in studies of type II SN. He i lines observed in early-time spectra are very well reproduced, even for very modest helium enrichments, likely resulting from treatment of important non-LTE effects. At similar early epochs CMFGEN predicts, unambiguously, the presence of N ii lines in the blue-wing of both H? and He I 5875 Å. These lines have been observed but so far have generally been associated with peculiar emission, from locations far above the photosphere, in the strong adjacent lines. Finally, we present a pedagogical investigation on P-Cygni profile formation in type II SN. H? is found to form very close to the photosphere and thus presents a significant flux-deficit in the red, made greater by the rapidly declining density distribution. This provides a clear explanation for the noticeable blue-shift of P-Cygni profiles observed in early-time spectra of type II SN. Future studies based on CMFGEN modeling will focus on using type II SN for the calibration of distances in the Universe, as well as on detailed spectroscopic analyses for the determination of progenitor properties.

Dessart, L.; Hillier, D. J.

2005-07-01

134

Quantitative high-resolution on-line NMR spectroscopy in reaction and process monitoring.  

PubMed

On-line nuclear magnetic resonance spectroscopy (on-line NMR) is a powerful technique for reaction and process monitoring. Different set-ups for direct coupling of reaction and separation equipment with on-line NMR spectroscopy are described. NMR spectroscopy can be used to obtain both qualitative and quantitative information from complex reacting multicomponent mixtures for equilibrium or reaction kinetic studies. Commercial NMR probes can be used at pressures up to 35 MPa and temperatures up to 400 K. Applications are presented for studies of equilibria and kinetics of complex formaldehyde-containing mixtures as well as homogeneously and heterogeneously catalyzed esterification kinetics. Direct coupling of a thin-film evaporator is described as an example for the benefits of on-line NMR spectroscopy in process monitoring. PMID:14729025

Maiwald, Michael; Fischer, Holger H; Kim, Young-Kyu; Albert, Klaus; Hasse, Hans

2004-02-01

135

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

SciTech Connect

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, B.; Hauff, P.; Goetz, A.F.H. [Univ. of Colorado, Boulder, CO (United States)

1994-02-01

136

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

137

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)

1999-03-01

138

Fluorescence Fluctuation Spectroscopy Enables Quantitative Imaging of Single mRNAs in Living Cells  

PubMed Central

Imaging mRNA with single-molecule sensitivity in live cells has become an indispensable tool for quantitatively studying RNA biology. The MS2 system has been extensively used due to its unique simplicity and sensitivity. However, the levels of the coat protein needed for consistent labeling of mRNAs limits the sensitivity and quantitation of this technology. Here, we applied fluorescence fluctuation spectroscopy to quantitatively characterize and enhance the MS2 system. Surprisingly, we found that a high fluorescence background resulted from inefficient dimerization of fluorescent protein (FP)-labeled MS2 coat protein (MCP). To mitigate this problem, we used a single-chain tandem dimer of MCP (tdMCP) that significantly increased the uniformity and sensitivity of mRNA labeling. Furthermore, we characterized the PP7 coat protein and the binding to its respective RNA stem loop. We conclude that the PP7 system performs better for RNA labeling. Finally, we used these improvements to study endogenous ?-actin mRNA, which has 24xMS2 binding sites inserted into the 3? untranslated region. The tdMCP-FP allowed uniform RNA labeling and provided quantitative measurements of endogenous mRNA concentration and diffusion. This work provides a foundation for quantitative spectroscopy and imaging of single mRNAs directly in live cells.

Wu, Bin; Chao, Jeffrey A.; Singer, Robert H.

2012-01-01

139

Quantitative analysis of the mixtures of illicit drugs using terahertz time-domain spectroscopy  

NASA Astrophysics Data System (ADS)

A method was proposed to quantitatively inspect the mixtures of illicit drugs with terahertz time-domain spectroscopy technique. The mass percentages of all components in a mixture can be obtained by linear regression analysis, on the assumption that all components in the mixture and their absorption features be known. For illicit drugs were scarce and expensive, firstly we used common chemicals, Benzophenone, Anthraquinone, Pyridoxine hydrochloride and L-Ascorbic acid in the experiment. Then illicit drugs and a common adulterant, methamphetamine and flour, were selected for our experiment. Experimental results were in significant agreement with actual content, which suggested that it could be an effective method for quantitative identification of illicit drugs.

Jiang, Dejun; Zhao, Shusen; Shen, Jingling

2008-03-01

140

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

141

Pungency evaluation of onion cultivars from the Venezuelan West-Center region by flow injection analysis–UV–visible spectroscopy pyruvate determination  

Microsoft Academic Search

A flow injection analysis (FIA) method was developed for the determination of pyruvate in onion cultivars (Allium cepa L.) from the West-Center region of Venezuela. The reference Schwimmer and Weston (1961) (J. Agric. Food Chem. 9 (1961) 301) Batch method was modified and adapted to FIA conditions. The formation kinetic of the 2,4-dinitrophenylhydrazine (DNPH)–pyruvate complex was evaluated at room temperature

Pineda Marcos; Marcó P. Lué-Merú; Rivas Ricardo; Gallignani Máximo; Valero Maribel; Burguera José Luis; Burguera Marcela

2004-01-01

142

Calibration of NO sensors for in-vivo voltammetry: laboratory synthesis of NO and the use of UV–visible spectroscopy for determining stock concentrations  

Microsoft Academic Search

The increasing scientific interest in nitric oxide (NO) necessitates the development of novel and simple methods of synthesising NO on a laboratory scale. In this study we have refined and developed a method of NO synthesis, using the neutral Griess reagent, which is inexpensive, simple to perform, and provides a reliable method of generating NO gas for in-vivo sensor calibration.

Finbar O. Brown; Niall J. Finnerty; Fiachra B. Bolger; Julian Millar; John P. Lowry

2005-01-01

143

Sensitive mercury speciation by reversed-phase column high-performance liquid chromatography with UV-visible detection after solid-phase extraction using 6-mercaptopurine and dithizone.  

PubMed

A highly selective and sensitive method was developed for preconcentration of inorganic and organic mercury compounds followed by reversed-phase column high-performance liquid chromatography (RP-HPLC) with UV-visible detection. The method was based on the reaction of mercury with 6-mercaptopurine and solid-phase extraction (SPE) of the complex on an octadecylsilane (C18) cartridge. The complex was then treated with ammoniacal dithizone solution, and the complexes of inorganic and organic mercury with dithizone were eluted by methanol. The speciation analysis of methylmercury (MeHg), phenylmercury (PhHg), and inorganic Hg (II) was carried out by RP-HPLC. Some experimental variables that influence the SPE and derivatization, such as pH, chelating and derivatizing agent concentration, and surfactant addition, were investigated. The calibration graphs of MeHg, PhHg, and Hg (II) were linear [correlation coefficient (r) > 0.999] from the detection limits (0.12, 0.16, and 0.14 ng) to 8.5, 6.0, and 6.7 ng Hg, respectively. By applying the SPE procedure, a 100-fold concentration of the sample was obtained. The procedure was applied to sea water and tuna fish samples. The method's accuracy was investigated by using tuna fish certified reference material BCR 464 and by spiking the samples with different amounts of MeHg, PhHg, and Hg (II). The average recoveries of MeHg, PhHg, and Hg (II) from spiked samples (0.1-2.0 microg/L Hg) were 96 +/- 4, 98 +/- 3, and 104 +/- 4%, respectively. PMID:19202808

Hashemi-Moghaddam, Hamid; Saber-Tehrani, Mohamad

144

Quantitation of vitamin B 12 by first-derivative absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Quantitation of vitamin B 12 by first-derivative absorption spectroscopy is described. Peak-to-peak (355 nm to 370 nm) amplitudes were measured from the first derivative spectra. The method permits rapid determination of vitamin B 12, and increases the detection limit while decreasing interference by impurities. The effects of the majority of other absorbing macromolecules which may also be present in biological samples are eliminated or very considerably minimized by this method.

Kar?ilayan, Huriye

1996-08-01

145

Quantitative analysis of lithium in Al-Li alloys by ionization energy loss spectroscopy  

Microsoft Academic Search

A quantitative analysis of lithium in Al-Li alloys has been carried out by ionization energy loss spectroscopy. It has been found that the power law I = A E gives the best fit to the background immediately preceding the Li-K edge, and that the optimum value of the spectrometer acceptance semi-angle ? is about 2 mrad. The Al:Li ratio on

Helen M. Chan; David B. Williams

1985-01-01

146

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

Microsoft Academic Search

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method is employed for quantitative determination of oxide\\u000a concentrations in multi-component materials. Industrial oxide materials from steel industry are laser ablated in air, and\\u000a the optical plasma emission is collected by spectrometers and gated detectors. The temperature and electron number density\\u000a of laser-induced plasma are determined from measured LIBS spectra. Emission lines of aluminium (Al),

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

147

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

Microsoft Academic Search

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°

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

2008-01-01

148

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

Microsoft Academic Search

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°

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

2008-01-01

149

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

150

Optimized external IR reflection spectroscopy for quantitative determination of borophosphosilicate glass parameters  

Microsoft Academic Search

Infrared (IR) external reflection spectroscopy has been optimized for the quantitative determination of composition and film thickness of borophosphosilicate glass (BPSG) deposited on silicon wafer substrates. The precision of the partial least-squares calibrations for boron and phosphorus contents and thin-film thickness were measured as the cross-validated standard error of prediction statistic. The results showed that BPSG IR reflection spectra collected

Lizhong Zhang; James E. Franke; Thomas M. Niemczyk; David M. Haaland

1997-01-01

151

Quantitative characterisation of historic paper using THz spectroscopy and multivariate data analysis  

NASA Astrophysics Data System (ADS)

THz spectroscopy in the time domain was explored in combination with multivariate data analysis, for quantitative determination of chemical and mechanical properties of historic paper, such as lignin content, tensile strength, and ash content. Using partial least squares (PLS) regression, it was shown that quantitative prediction of the material properties is possible, which indicates the potential of THz spectroscopy for chemical characterisation of complex organic materials of natural origin. In addition, the results demonstrate that THz spectra and PLS loading weights for lignin content differ significantly, which leads to the conclusion that THz spectra of composite macromolecular materials do not represent sums of spectra of the individual components. This supports the premise that THz spectra reflect intermolecular interactions. The study was carried out using 250 historical paper samples from the sixteenth century to present. Although the measurements were performed in vacuum to improve the quality of spectra, THz spectroscopy is in principle non-destructive. This research therefore reinforces the role of THz spectroscopy in characterisation of valuable historic materials, where invasive analysis is often not possible.

Trafela, Tanja; Mizuno, Maya; Fukunaga, Kaori; Strli?, Matija

2013-04-01

152

The Lightning Rod Model: a Genesis for Quantitative Near-Field Spectroscopy  

NASA Astrophysics Data System (ADS)

Near-field infrared spectroscopy has the proven ability to resolve optical contrasts in materials at deeply sub-wavelength scales across a broad range of infrared frequencies. In principle, the technique enables sub-diffractional optical identification of chemical compositions within nanostructured and naturally heterogeneous samples. However current models of probe-sample optical interaction, while qualitatively descriptive, cannot quantitatively explain infrared near-field spectra, especially for strongly resonant sample materials. We present a new first-principles model of near-field interaction, and demonstrate its superb agreement with infrared near-field spectra measured for thin films of silicon dioxide and the strongly phonon-resonant material silicon carbide. Using this model we reveal the role of probe geometry and surface mode dispersion in shaping the measured near-field spectrum, establishing its quantitative relationship with the dielectric properties of the sample. This treatment offers a route to the quantitative determination of optical constants at the nano-scale.

McLeod, Alexander; Andreev, Gregory; Dominguez, Gerardo; Thiemens, Mark; Fogler, Michael; Basov, D. N.

2013-03-01

153

Quantitative {sup 29}Si MAS NMR spectroscopy of cement and silica fume containing paramagnetic impurities  

SciTech Connect

The low natural abundance and the long spin lattice relaxation time of {sup 29}Si lead to long measurement times and/or low signal-to-noise ratios using {sup 29}Si magic angle spinning NMR spectroscopy. By contrast, samples containing paramagnetic iron ions have much shorter relaxation times, making measurements up to seven times more efficient, but at the same time making quantitative analysis unreliable. To solve the problem, the spin-lattice relaxation times of ordinary Portland cement (opc) and silica fume with and without iron content has been determined with inversion recovery experiments. The effect of varying the spectrum repetition time on the quantitative analysis is demonstrated for mixtures of opc with silica fume. For opc and silica fume with iron impurities repetition times as short as 5 s has permitted accurate quantitative analysis of the silicates present in these materials.

Hilbig, H. [Center of Building Materials (CBM), Technische Universitaet Muenchen, Baumbachstr. 7, D-81245 Munich (Germany)]. E-mail: hilbig@cbm.bv.tum.de; Koehler, F.H. [Department Chemie, Technische Universitaet Muenchen, D-85747 Garching (Germany); Schiessl, P. [Center of Building Materials (CBM), Technische Universitaet Muenchen, Baumbachstr. 7, D-81245 Munich (Germany)

2006-02-15

154

Introduction to Spectroscopy  

NSDL National Science Digital Library

This site covers introductory material related to the analysis of small organic molecules by mass spectrometry, UV-visible, IR, and NMR spectroscopy. A concise explanation of each approach is presented with illustrations. This would be useful for those teaching organic chemistry and for others who need a review of the topic. The section on Spectroscopy Resources at the end of the site contains a list of links to additional information plus a several links to compilations of problems (and their solutions) that challenge the student to interpret NMR or IR spectra.

Reusch, William

2007-08-10

155

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.

2012-05-01

156

NDACC/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative ground-based and satellite observations  

NASA Astrophysics Data System (ADS)

Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers. These instruments, deployed all over the world in about 35 stations, allow measuring total ozone twice daily with limited sensitivity to stratospheric temperature and cloud cover. The NDACC recommendations address both the DOAS spectral parameters and the calculation of air mass factors (AMF) needed for the conversion of O3 slant column densities into vertical column amounts. The most important improvement is the use of O3 AMF look-up tables calculated using the TOMS V8 (TV8) O3 profile climatology, that allows accounting for the dependence of the O3 AMF on the seasonal and latitudinal variations of the O3 vertical distribution. To investigate their impact on the retrieved ozone columns, the recommendations have been applied to measurements from the NDACC/SAOZ (Système d'Analyse par Observation Zénithale) network. The revised SAOZ ozone data from eight stations deployed at all latitudes have been compared to TOMS, GOME-GDP4, SCIAMACHY-TOSOMI, SCIAMACHY-OL3, OMI-TOMS, and OMI-DOAS satellite overpass observations, as well as to those of collocated Dobson and Brewer instruments at Observatoire de Haute Provence (44° N, 5.5° E) and Sodankyla (67° N, 27° E), respectively. A significantly better agreement is obtained between SAOZ and correlative reference ground-based measurements after applying the new O3 AMFs. However, systematic seasonal differences between SAOZ and satellite instruments remain. These are shown to mainly originate from (i) a possible problem in the satellite retrieval algorithms in dealing with the temperature dependence of the ozone cross-sections in the UV and the solar zenith angle (SZA) dependence, (ii) zonal modulations and seasonal variations of tropospheric ozone columns not accounted for in the TV8 profile climatology, and (iii) uncertainty on the stratospheric ozone profiles at high latitude in the winter in the TV8 climatology. For those measurements mostly sensitive to stratospheric temperature like TOMS, OMI-TOMS, Dobson and Brewer, or to SZA like SCIAMACHY-TOSOMI, the application of temperature and SZA corrections results in the almost complete removal of the seasonal difference with SAOZ, improving significantly the consistency between all ground-based and satellite total ozone observations.

Hendrick, F.; Pommereau, J.-P.; Goutail, F.; Evans, R. D.; Ionov, D.; Pazmino, A.; Kyrö, E.; Held, G.; Eriksen, P.; Dorokhov, V.; Gil, M.; van Roozendael, M.

2011-06-01

157

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

158

Comparison of photoacoustic spectroscopy, conventional absorption spectroscopy, and potentiometry as probes of lanthanide speciation  

Microsoft Academic Search

The authors measured the stability constants of praseodymium acetate and oxydiacetate complexes by laser-induced photoacoustic spectroscopy, conventional UV-visible absorption spectroscopy, and pH titration. For the spectroscopic studies, changes in the free Pr absorption peaks at 468 and 481 nm were monitored at varying ligand concentrations. The total Pr concentration was 1 à 10⁻⁴ M in solutions used for the photoacoustic

Richard A. Torres; Cynthia E. A. Palmer; Patricia A. Baisden; Richard E. Russo; Robert J. Silva

1990-01-01

159

Quantitative and qualitative analysis of urine component in the toilet set using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

As a part of non-invasive and unaware measurement of physiological signal in the house of live-alone person, Raman spectroscopy was applied for urine component analysis in the toilet set. 785nm, 250-300mW output solid state diode laser and 2048 element linear silicon TE cooled CCD array were incorporated for this system. Several tests were performed for setting up Raman spectroscopy in non-constrained situation: toilet set in the house. The effect of dark current, integration time, warming up time of laser, property of probe and interference of water in the toilet were tested and controlled for appropriate measurement in this environment. The spectra were obtained immediately when the subject uses the toilet set, and they can be transmitted to the server though Bluetooth. Those spectra were pre-processed for removing or correcting the effect of undesired light scattering, sample path-length difference and baseline-effect. The preprocessed data were enhanced for more exact result of multivariate analysis. The training data was prepared for predicting unknown component and its concentration by using multivariate methods. Several kinds of multivariate methods: PCA, PCR, PLS were performed to validate what is the fittest method in this environment. Through quantitative and qualitative analysis of Raman spectroscopy"s spectra obtained in the house's toilet set, we could know the component and its concentration of urine which can be index of disease.

Chung, So Hyun; Park, Kwang Suk; Choi, Jong Min; Lee, Won Jin

2004-07-01

160

Quantitative x-ray photoelectron spectroscopy study of Al/AlOx bilayers  

NASA Astrophysics Data System (ADS)

An x-ray photoelectron spectroscopy (XPS) analysis of Nb/Al wedge bilayers, oxidized by both plasma and natural oxidation, is reported. The main goal is to show that the oxidation state--i.e., O:(oxidize)Al ratio--, structure and thickness of the surface oxide layer, as well as the thickness of the metallic Al leftover, as functions of the oxidation procedure, can be quantitatively evaluated from the XPS spectra. This is relevant to the detailed characterization of the insulating barriers in (magnetic) tunnel junctions.

Batlle, Xavier; Hattink, Bart Jan; Labarta, Amilcar; Akerman, Johan J.; Escudero, Roberto; Schuller, Ivan K.

2002-06-01

161

Quantitative Analysis for Monitoring Formulation of Lubricating Oil Using Terahertz Time-Domain Transmission Spectroscopy  

NASA Astrophysics Data System (ADS)

The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS). Compared with the middle-infrared spectra of zinc n-butyl-isooctyl-dithiophosphate (T202) and T204, THz spectra of T202 and T204 show the weak broad absorption bands. Then, the absorption coefficients of the T204-Korea70 system follow Beer's law at the concentration from 0.124 to 4.024%. The experimental absorption spectra of T204-Korea70 agree with the calculated ones based on the standard absorption coefficients of T204 and Korea70. The quantitative analysis enables a strategy to monitor the formulation of lubricating oil in real time.

Tian, Lu; Zhao, Kun; Zhou, Qing-Li; Shi, Yu-Lei; Zhang, Cun-Lin

2012-04-01

162

Artificial neural network for on-site quantitative analysis of soils using laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Nowadays, due to environmental concerns, fast on-site quantitative analyses of soils are required. Laser induced breakdown spectroscopy is a serious candidate to address this challenge and is especially well suited for multi-elemental analysis of heavy metals. However, saturation and matrix effects prevent from a simple treatment of the LIBS data, namely through a regular calibration curve. This paper details the limits of this approach and consequently emphasizes the advantage of using artificial neural networks well suited for non-linear and multi-variate calibration. This advanced method of data analysis is evaluated in the case of real soil samples and on-site LIBS measurements. The selection of the LIBS data as input data of the network is particularly detailed and finally, resulting errors of prediction lower than 20% for aluminum, calcium, copper and iron demonstrate the good efficiency of the artificial neural networks for on-site quantitative LIBS of soils.

El Haddad, J.; Villot-Kadri, M.; Ismaël, A.; Gallou, G.; Michel, K.; Bruyère, D.; Laperche, V.; Canioni, L.; Bousquet, B.

2013-01-01

163

Quantitative laser-induced breakdown spectroscopy analysis of calcified tissue samples  

NASA Astrophysics Data System (ADS)

We report on the application of laser-induced breakdown spectroscopy (LIBS) to the analysis of important minerals and the accumulation of potentially toxic elements in calcified tissue, to trace e.g. the influence of environmental exposure, and other medical or biological factors. This theme was exemplified for quantitative detection and mapping of Al, Pb and Sr in representative samples, including teeth (first teeth of infants, second teeth of children and teeth of adults) and bones (tibia and femur). In addition to identifying and quantifying major and trace elements in the tissues, one- and two-dimensional profiles and maps were generated. Such maps (a) provide time/concentration relations, (b) allow to follow mineralisation of the hydroxyapatite matrix and the migration of the elements within it and (c) enable to identify disease states, such as caries in teeth. In order to obtain quantitative calibration, reference samples in the form of pressed pellets with calcified tissue-equivalent material (majority compound of pellets is CaCO 3) were used whose physical properties closely resembled hydroxyapatite. Compounds of Al, Sr and Pb were added to the pellets, containing atomic concentrations in the range 100-10 000 ppm relative to the Ca content of the matrix. Analytical results based on this calibration against artificial samples for the trace elements under investigation agree with literature values, and with our atomic absorption spectroscopy (AAS) cross-validation measurements.

Samek, O.; Beddows, D. C. S.; Telle, H. H.; Kaiser, J.; Liška, M.; Cáceres, J. O.; Gonzáles Ureña, A.

2001-06-01

164

Quantitative analysis of alpha-D-glucose in an ionic liquid by using infrared spectroscopy.  

PubMed

The applicability of infrared (IR) spectroscopy for quantitative concentration measurements in mixtures of carbohydrates and ionic liquids (ILs) is investigated. The compound 1-ethyl-3-methylimidazolium acetate, [EMIM][OAc]-an "enzyme-friendly" ionic liquid with great application potential in the dissolution of various biomasses-is used as solvent in combination with alpha-D-glucose. Our study establishes a new way to monitor the concentration of sugars in ILs, thus providing a convenient method to follow the kinetics of, for example, enzymatic reactions in [EMIM][OAc]. As a first step, we present the IR spectrum of pure [EMIM][OAc] (this constitutes the first vibrational study of this particular IL). Although numerous lines overlap in the fingerprint region of the spectrum, characteristic features can be assigned to the corresponding vibrational modes of both ions. Secondly, we study different mixtures of the IL with alpha-D-glucose (in the concentration range: 0-20 mass % glucose) and analyze them by means of IR spectroscopy, followed by computational methods, thus demonstrating the great potential of this spectroscopic technique in quantitative measurements. PMID:18442034

Kiefer, Johannes; Obert, Katharina; Bösmann, Andreas; Seeger, Thomas; Wasserscheid, Peter; Leipertz, Alfred

2008-06-23

165

Quantitation of crystalline and amorphous forms of anhydrous neotame using 13C CPMAS NMR spectroscopy.  

PubMed

Although most drugs are formulated in the crystalline state, amorphous or other crystalline forms are often generated during the formulation process. The presence of other forms can dramatically affect the physical and chemical stability of the drug. The identification and quantitation of different forms of a drug is a significant analytical challenge, especially in a formulated product. The ability of solid-state 13C NMR spectroscopy with cross polarization (CP) and magic-angle spinning (MAS) to quantify the amounts of three of the multiple crystalline and amorphous forms of the artificial sweetener neotame is described. It was possible to quantify, in a mixture of two anhydrous polymorphic forms of neotame, the amount of each polymorph within 1-2%. In mixtures of amorphous and crystalline forms of neotame, the amorphous content could be determined within 5%. It was found that the crystalline standards that were used to prepare the mixtures were not pure crystalline forms, but rather a mixture of crystalline and amorphous forms. The effect of amorphous content in the crystalline standards on the overall quantitation of the two crystalline polymorphic forms is discussed. The importance of differences in relaxation parameters and CP efficiencies on quantifying mixtures of different forms using solid-state NMR spectroscopy is also addressed. PMID:16258988

Offerdahl, Thomas J; Salsbury, Jonathon S; Dong, Zedong; Grant, David J W; Schroeder, Stephen A; Prakash, Indra; Gorman, Eric M; Barich, Dewey H; Munson, Eric J

2005-12-01

166

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

2011-06-12

167

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

2012-04-27

168

Fast and accurate quantitation of glucans in complex mixtures by optimized heteronuclear NMR spectroscopy.  

PubMed

Nuclear magnetic resonance (NMR) spectroscopy is a widely used technique for mixture analysis, but it has shortcomings in resolving carbohydrate mixtures due to the narrow chemical shift range of glycans in general and fragments of homopolymers in particular. Here, we suggest a protocol toward fast spectroscopic glycan mixture analysis. We show that a plethora of oligosaccharides comprising only ?-glucopyranosyl residues can be resolved into distinct quantifiable signals with NMR experiments that are substantially faster than chromatographic runs. Conceptually, the approach fully exploits the narrow line widths of glycans (?1/2 < 3 Hz) in the (13)C spectral dimension while disregarding superfluous spectral information in compound identification and quantitation. The acetal (H1C1) groups suffice to spectroscopically resolve ?20 different starch fragments in optimized (1)H-(13)C NMR with a narrow (13)C spectral width (3 ppm) that allows sampling the indirect (13)C dimension at high resolution within 15 min. Rapid quantitations by high-resolution NMR data are achieved for glycans at concentrations as low as 10 ?g/mL. For validation, comparisons were made with quantitations obtained by more time-consuming chromatographic methods and yielded coefficients of determination (R(2)) above 0.99. PMID:23952648

Bøjstrup, Marie; Petersen, Bent O; Beeren, Sophie R; Hindsgaul, Ole; Meier, Sebastian

2013-08-23

169

Operator representation as a new differential optical absorption spectroscopy formalism.  

PubMed

UV-visible absorption spectroscopy with extraterrestrial light sources is a widely used technique for the measurement of stratospheric and tropospheric trace gases. We focus on differential optical absorption spectroscopy (DOAS) and present an operator notation as a new formalism to describe the different processes in the atmosphere and the simplifying assumptions that compose the advantage of DOAS. This formalism provides tools to classify and reduce possible error sources of DOAS applications. PMID:15943258

Wenig, Mark; Jähne, Bernd; Platt, Ulrich

2005-06-01

170

Quantitative detection of plasma-generated radicals in liquids by electron paramagnetic resonance spectroscopy  

NASA Astrophysics Data System (ADS)

In this paper the qualitative and quantitative detection of oxygen radicals in liquids after plasma treatment with an atmospheric pressure argon plasma jet by electron paramagnetic resonance spectroscopy is investigated. Absolute values for ·OH and O_{2}^{\\cdot -} radical concentration and their net production rate in plasma-treated liquids are determined without the use of additional scavenging chemicals such as superoxide dismutase (SOD) or mannitol (D-MAN). The main oxygen-centred radical generation in PBS was found to originate from the superoxide radical. It is shown that hidden parameters such as the manufacturer of chemical components could have a big influence on the comparability and reproducibility of the results. Finally, the effect of a shielding gas device for the investigated plasma jet with a shielding gas composition of varying oxygen-to-nitrogen ratio on radical generation after plasma treatment of phosphate-buffered saline solution was investigated.

Tresp, H.; Hammer, M. U.; Winter, J.; Weltmann, K.-D.; Reuter, S.

2013-10-01

171

Quantitation of pH-induced aggregation in binary protein mixtures by dielectric spectroscopy.  

PubMed

This paper presents a quantitative approach for measuring pH-controlled protein aggregation using dielectric spectroscopy. The technique is demonstrated through two aggregation experiments, the first between ?-lactoglobulin (?-Lg) and hen lysozyme (HENL) and the second between bovine serum albumin (BSA) and HENL. In both experiments, the formation of aggregates is strongly dependent on the solution pH and is clearly indicated by a decrease in the measured permittivity when the second protein is added. A quantifiable lower-bound on the ratio of proteins involved in the aggregation process is obtained from the permittivity spectra. Lower-bound aggregation ratios of 83 % for ?-Lg/HENL at pH 6.0 and 48 % for BSA/HENL at pH 9.2 were consistent with turbidity measurements made on the same solutions. PMID:23001617

Mellor, Brett L; Wood, Stephen J; Mazzeo, Brian A

2012-12-01

172

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

173

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.

174

One-point calibration for calibration-free laser-induced breakdown spectroscopy quantitative analysis  

NASA Astrophysics Data System (ADS)

We present a new method for improving the reliability of quantitative analysis by laser-induced breakdown spectroscopy (LIBS). The method can be considered as a variation of the calibration-free LIBS approach; although not completely standard-less, only one standard of known composition and similar matrix to the one to be analyzed is needed. On the other hand, the one-point calibration approach allows the empirical determination of essential experimental and spectroscopic parameters, whose knowledge is often imprecise or lacking; the result is a definite improvement of the trueness of LIBS analysis with respect to the traditional calibration-free approach. The characteristics and advantages of the proposed one-point calibration LIBS approach will be demonstrated on a set of copper-based samples of known composition.

Cavalcanti, G. H.; Teixeira, D. V.; Legnaioli, S.; Lorenzetti, G.; Pardini, L.; Palleschi, V.

2013-09-01

175

Identification and quantitative determination of lignans in Cedrus atlantica resins using 13C NMR spectroscopy.  

PubMed

Identification and quantitative determination of individual components of resin collected on the trunk of 28 Cedrus atlantica trees, grown in Corsica, has been carried out using 13C NMR spectroscopy. Eight resin acids bearing either the pimarane or abietane skeleton, two monoterpene hydrocarbons and four oxygenated neutral diterpenes have been identified, as well as three lignans, scarcely found in resins. Three groups could be distinguished within the 28 resin samples. The nine samples of Group I had their composition dominated by diterpene acids (33.7-45.8%), with abietic acid (6.2-18.7%) and isopimaric acid (5.1-12.6%) being the major components. The four samples of Group II contained resin acids (main components) and lignans in moderate amounts (up to 10.3%). Conversely, lignans (38.8-63.8%) were by far the major components of the 15 samples of Group III. Depending on the sample, the major component was pinoresinol (18.1-38.9%), lariciresinol (17.2-33.7%) or lariciresinol 9'-acetate (16.9-29.1%). Finally, due to the high biological interest in lignans, a rapid procedure, based on 1H NMR spectroscopy, was developed for quantification of lignans in resins of C. atlantica. PMID:21485279

Nam, Anne-Marie; Paoli, Mathieu; Castola, Vincent; Casanova, Joseph; Bighelli, Ange

2011-03-01

176

Optimized external IR reflection spectroscopy for quantitative determination of borophosphosilicate glass parameters  

SciTech Connect

Infrared (IR) external reflection spectroscopy has been optimized for the quantitative determination of composition and film thickness of borophosphosilicate glass (BPSG) deposited on silicon wafer substrates. The precision of the partial least-squares calibrations for boron and phosphorus contents and thin-film thickness were measured as the cross-validated standard error of prediction statistic. The results showed that BPSG IR reflection spectra collected over a wide range of incident IR radiation angles (15{degree}, 25{degree}, 45{degree}, and 60{degree}) can be used for the simultaneous quantification of these three BPSG parameters. When high angles of incidence were employed, the measurement was found to be more sensitive to small errors in the angle of incidence. The polarization state of the incident IR radiation did not noticeably affect the prediction of the three calibrated BPSG parameters. The results achieved in this study provide guidelines for at-line process monitoring and quality control of BPSG thin films used in the fabrication of microelectronic devices. {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

Zhang, L.; Franke, J.E.; Niemczyk, T.M. [Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Haaland, D.M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0342 (United States)

1997-02-01

177

[Simultaneous quantitative determination of multicomponents in tablets based on terahertz time-domain spectroscopy].  

PubMed

Terahertz time-domain spectroscopy (THz-TDS) combined with chemometric modeling methods was used to perform quantitative analysis of both active pharmaceutical ingredient (API) and excipient concentrations of multicomponent pharmaceutical mixtures. The THz spectra of ternary mixtures formulated with anhydrous theophylline, lactose monohydrate, magnesium stearate and quaternary mixtures composed of acetaminophen, lactose monohydrate, microcrystalline cellulose and soluble starch were measured using THz-TDS. Two multivariate calibration methods, principal component regression (PCR) and partial least squares (PLS) regression, were employed to correlate THz absorbance spectra with the pharmaceutical tablet concentrations. Both API and excipient concentrations of mixtures were predicted simultaneously, and the PLS method provides better result than PCR method. The correlation coefficients of calibration (Rcal) and validation (Rval) for ternary mixtures' components, anhydrous theophylline and lactose monohydrate, were all more than 0.98. The Rcal and Rval for quaternary mixtures' components, acetaminophen, lactose monohydrate, microcrystalline cellulose and soluble starch, were all more than 0.93, 0.98, 0.63 and 0.86, respectively. Experimental results show that THz-TDS combined with chemometrics is feasible in nondestructive quantitative analysis of multicomponent mixtures, and it can be widely applied in the fields of pharmaceutical analysis and others. PMID:23905323

Chen, Tao; Li, Zhi; Mo, Wei; Hu, Fang-Rong

2013-05-01

178

Quantitative analysis of protein backbone dynamics in microcrystalline ubiquitin by solid-state NMR spectroscopy.  

PubMed

Characterization of protein dynamics by solid-state NMR spectroscopy requires robust and accurate measurement protocols, which are not yet fully developed. In this study, we investigate the backbone dynamics of microcrystalline ubiquitin using different approaches. A rotational-echo double-resonance type (REDOR-type) methodology allows one to accurately measure (1)H-(15)N order parameters in highly deuterated samples. We show that the systematic errors in the REDOR experiment are as low as 1% or even less, giving access to accurate data for the amplitudes of backbone mobility. Combining such dipolar-coupling-derived order parameters with autocorrelated and cross-correlated (15)N relaxation rates, we are able to quantitate amplitudes and correlation times of backbone dynamics on picosecond and nanosecond time scales in a residue-resolved manner. While the mobility on picosecond time scales appears to have rather uniform amplitude throughout the protein, we unambiguously identify and quantitate nanosecond mobility with order parameters S(2) as low as 0.8 in some regions of the protein, where nanosecond dynamics has also been revealed in solution state. The methodology used here, a combination of accurate dipolar-coupling measurements and different relaxation parameters, yields details about dynamics on different time scales and can be applied to solid protein samples such as amyloid fibrils or membrane proteins. PMID:20977205

Schanda, Paul; Meier, Beat H; Ernst, Matthias

2010-10-26

179

Quantitative analysis of boron oxide in borosilicate glasses by infrared spectroscopy  

SciTech Connect

Classical multivariate least-squares methods have been applied to the quantitative analysis of boron oxide in bulk borosilicate glasses using transmission infrared spectroscopy. However, molecular interactions in the glass result in deviation from Beer's law and cause the analytical B-O overtone band at --2680 cm/sup -1/ to shift to higher energy with increased boron concentration. Therefore, in order to account for the molecular interactions and achieve higher quantitative accuracy, one must use a nonlinear model relating absorbance and concentration. It has been found that if a quadratic correction term is added to the Beer's-law equation, the observed 15 to 25 cm/sup -1/ shift in frequency of the B-O overtone band can be modeled to within the spectral noise. With the use of a model quadratic in boron oxide concentration, the least-squares analysis of boron in glass was determined with an average relative error of 3.3% for glasses with boron oxide concentrations ranging from 0.88 to 2.58%. This compares favorably with the 3% accuracy claimed for ion chromatography exculsion used for calibration. The methods described in this paper are general, and a variety of nonlinear models can be applied whenever Beer's-law deviations are present.

Haaland, D.M.

1986-11-01

180

Quantitative high-resolution photoacoustic spectroscopy by combining photoacoustic imaging with diffuse optical tomography  

NASA Astrophysics Data System (ADS)

The specificity of both molecular and functional photoacoustic (PA) images depends on the accuracy of the photoacoustic absorption spectroscopy. Because the PA signal is a product of both the optical absorption coefficient and the local light fluence, quantitative PA measurements of absorption require an accurate estimate of the optical fluence. Lightmodeling aided by diffuse optical tomography (DOT) methods can be used to provide the required fluence map and to reduce errors in traditional PA spectroscopic analysis. As a proof-ofconcept, we designed a phantom to demonstrate artifacts commonly found in photoacoustic tomography (PAT) and how fluence-related artifacts in PAT images can lead to misrepresentations of tissue properties. Specifically, we show that without accounting for fluence-related inhomogeneities in our phantom, errors in estimates of the absorption coefficient from a PAT image were as much as 33%. To correct for this problem, DOT was used to reconstruct spatial distributions of the absorption coefficients of the phantom, and along with the surface fluence distribution from the PAT system, we calculated the fluence everywhere in the phantom. This fluence map was used to correct PAT images of the phantom, reducing the error in the estimated absorption coefficient from the PAT image to less than 5%. Thus, we demonstrate experimentally that combining DOT with PAT can significantly reduce fluence-related errors in PAT images, as well as produce quantitatively accurate, highresolution images of the optical absorption coefficient.

Bauer, Adam Q.; Nothdurft, Ralph E.; Erpelding, Todd N.; Wang, Lihong V.; Culver, Joseph P.

2011-02-01

181

Quantitative analysis of cefalexin based on artificial neural networks combined with modified genetic algorithm using short near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

In this paper, a novel chemometric method was developed for rapid, accurate, and quantitative analysis of cefalexin in samples. The experiments were carried out by using the short near-infrared spectroscopy coupled with artificial neural networks. In order to enhancing the predictive ability of artificial neural networks model, a modified genetic algorithm was used to select fixed number of wavelength.

Huan, Yanfu; Feng, Guodong; Wang, Bin; Ren, Yulin; Fei, Qiang

2013-05-01

182

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

Microsoft Academic Search

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

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

2003-01-01

183

Quantitative analysis of mercury in silver dental amalgam alloy using laser induced breakdown spectroscopy with a portable Echelle spectrometer  

Microsoft Academic Search

Nowadays it is commonly ascertained that, Laser- induced breakdown spectroscopy (LIBS) was investigated to evaluate the feasibility as a fast, accurate, non contact and simple technique used in both qualitative and quantitative elemental analysis of metals in various environments. The used portable Echelle spectrometer (Mechelle 7500 - Multichannel Instruments, Stockholm, Sweden) permit real simultaneous multi-elemental analysis in rang of 200-900

Walid Tawfik; Ali Saafan

184

Quantitative determination of the cubic-to-monoclinic phase transformation in fully stabilized zirconias by Raman spectroscopy  

Microsoft Academic Search

Vibrational Raman spectroscopy was used successfully for the quantitative determination of the cubic and monoclinic phases of zirconia. Pressed pellets with known composition were prepared using monoclinic and cubic powders from different manufacturers and were used as standard mixtures. An intensity ratio plot of the 617-cm[sup [minus]1] band, which is attributed to the presence of both phases, to either the

Christos G. Kontoyannis; George Carountzos

1994-01-01

185

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

186

Quantitative analysis of chemically amplified negative photoresist using mirror-backed infrared reflection absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Infrared spectroscopy is a powerful tool for studying chemical reactions which take place in photoresist films. It provides information about functional groups present in the material, is nondestructive to the sample, can be used to monitor reactions in real-time, and can be used as a monitor for real-time process control. Transmission spectroscopy has been used for determination of rate constants for the post exposure bake (PEB) step in both positive and negative chemically amplified x-ray resists, but in transmission the IR beam must pass through the wafer in order to reach the detector. Reflection spectroscopy is more suitable for on-line monitoring because all the optics are located on the same side of the wafer; however, traditional reflection spectra of thin films contain interference fringes which make quantitative analysis difficult. We have developed a method, called mirror-backed infrared reflection- absorption spectroscopy (MBIRRAS), that eliminates the problem of interference fringes in reflection spectra. The method is capable of providing quantitative information about the concentration of functional groups in resist films and produced a linear calibration curve for a commercial crosslinker (hexamethoxymethylmelamine) in a Novolac matrix over a 20% by weight range of concentrations. MBIRRAS was also used to monitor the height of an IR peak corresponding to formation of crosslinks in Shipley negative-tone resist SAL 605 at various processing conditions. The results of this experiment show that PEB time and temperature, prebake time and temperature, and delay between exposure and PEB, all have statistically significant effects on the extent of crosslinking during PEB. In order to explain the observed effect of prebake conditions on the amount of crosslinking during the PEB step and to define the acceptable range of prebaking conditions for resist/wafer adhesion studies, another experiment was performed to demonstrate that thermally generated crosslinking occurred during an additional prebake step without any exposure to x rays. In fact, an additional prebake for 60 seconds at 110 degree(s)C can generate the same number of crosslinks as an x- ray dose of 4 mJ/cm2, while baking for 60 minutes at 110 degree(s)C is equivalent to an x-ray dose that is greater than the resist sensitivity (42 mJ/cm2). Noticeable changes in crosslink concentration were detected at 30 seconds. This suggests that crosslinking occurs during the normal prebake step and explains the dependence of linewidth on prebake time. Finally, a correlation was demonstrated between printed linewidth and MBIRRAS peak height corresponding to crosslink formation in SAL 605. This correlation, along with the demonstrated precision of the MBIRRAS method (3 sigma

Gamsky, Chris J.; Dentinger, Paul M.; Howes, Glenn R.; Taylor, James W.

1995-06-01

187

Quantitative C2H2 measurements in sooty flames using mid-infrared polarization spectroscopy  

NASA Astrophysics Data System (ADS)

Quantitative measurements of acetylene (C2H2) molecules as a combustion intermediate species in a series of rich premixed C2H4/air flames were non-intrusively performed, spatially resolved, using mid-infrared polarization spectroscopy (IRPS), by probing its fundamental ro-vibrational transitions. The flat sooty C2H4/air premixed flames with different equivalence ratios varying from 1.25 to 2.50 were produced on a 6 cm diameter porous-plug McKenna type burner at atmospheric pressure, and all measurements were performed at a height of 8.5 mm above the burner surface. IRPS excitation scans in different flame conditions were performed and rotational line-resolved spectra were recorded. Spectral features of acetylene molecules were readily recognized in the spectral ranges selected, with special attention to avoid the spectral interference from the large amount of coexisting hot water and other hydrocarbon molecules. On-line calibration of the optical system was performed in a laminar C2H2/N2 gas flow at ambient conditions. Using the flame temperatures measured by coherent anti-Stokes Raman spectroscopy in a previous work, C2H2 mole fractions in different flames were evaluated with collision effects and spectral overlap between molecular line and laser source being analyzed and taken into account. C2H2 IRPS signals in two different buffering gases, N2 and CO2, had been investigated in a tube furnace in order to estimate the spectral overlap coefficients and collision effects at different temperatures. The soot-volume fractions (SVF) in the studied flames were measured using a He-Ne laser-extinction method, and no obvious degrading of the IRPS technique due to the sooty environment has been observed in the flame with SVF up to ˜2×10-7. With the increase of flame equivalence ratios not only the SVF but also the C2H2 mole fractions increased.

Sun, Z. W.; Li, Z. S.; Li, B.; Alwahabi, Z. T.; Aldén, M.

2010-10-01

188

Quantitative determination of borophosphosilicate glass thin-film properties using infrared emission spectroscopy  

SciTech Connect

We have completed an experimental study to investigate the use of infrared emission spectroscopy (IRES) for the quantitative analysis of borophosphosilicate glass (BPSG) thin films on silicon monitor wafers. Experimental parameters investigated included temperatures within the range used in the microelectronics industry to produce these films so that the potential for using the IRES technique for real-time monitoring of the film deposition process could be evaluated. The film properties that were investigated included boron content, phosphorus content, film thickness, and film temperature. The studies were conducted over two temperature ranges, 125 to 225&hthinsp;{degree}C and 300 to 400&hthinsp;{degree}C. The latter temperature range includes realistic processing temperatures for the chemical vapor deposition (CVD) of the BPSG films. Partial least-squares (PLS) multivariate calibration methods were applied to spectral and film property calibration data. The cross-validated standard errors of prediction (CVSEP) from the PLS analysis of the IRES spectra of 21 calibration samples each measured at six temperatures in the 300 to 400&hthinsp;{degree}C range were found to be 0.09 wt {percent} for B, 0.08 wt {percent} for P, 3.6 nm for film thickness, and 1.9&hthinsp;{degree}C for temperature. Upon lowering the spectral resolution from 4 to 32 cm{sup {minus}1} and decreasing the number of spectral scans from 128 to 1, we were able to determine that all the film properties could be measured in less than one second to the precision required for the manufacture and quality control of integrated circuits. Thus, real-time {ital in situ} monitoring of BPSG thin films formed by CVD deposition on Si monitor wafers is possible with the methods reported here. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}

Niemczyk, T.M.; Zhang, S.; Franke, J.E. [Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] Haaland, D.M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0342 (United States)

1999-07-01

189

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

190

Assessment of breast tumor margins via quantitative diffuse reflectance imaging  

NASA Astrophysics Data System (ADS)

A particular application of interest for tissue reflectance spectroscopy in the UV-Visible is intraoperative detection of residual cancer at the margins of excised breast tumors, which could prevent costly and unnecessary repeat surgeries. Our multi-disciplinary group has developed an optical imaging device, which is capable of surveying the entire specimen surface down to a depth of 1-2mm, all within a short time as required for intraoperative use. In an IRB-approved study, reflectance spectral images were acquired from 54 margins in 48 patients. Conversion of the spectral images to quantitative tissue parameter maps was facilitated by a fast scalable inverse Monte-Carlo model. Data from margin parameter images were reduced to image-descriptive scalar values and compared to gold-standard margin pathology. The utility of the device for classification of margins was determined via the use of a conditional inference tree modeling approach, and was assessed both as a function of type of disease present at the margin, as well as a function of distance of disease from the issue surface. Additionally, the influence of breast density on the diagnostic parameters, as well as the accuracy of the device, was evaluated.

Brown, J. Quincy; Bydlon, Torre M.; Kennedy, Stephanie A.; Geradts, Joseph; Wilke, Lee G.; Barry, William; Richards, Lisa M.; Junker, Marlee K.; Gallagher, Jennifer; Ramanujam, Nimmi

2010-02-01

191

Quantitative determination of sulfur content in concrete with laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy has been employed for the investigation of the sulfur content of concrete. Sulfur compounds are a natural but minor component in building materials. The ingress of sulfates or sulfuric acid constitutes a major risk of chemical aggression for concrete. There is a need for a fast method, which can be used on-site and is able to investigate a wide range of different measuring points, so that damages can be characterized. For quantitative determination the sulfur spectral line at 921.3 nm is used. The optimum ambient atmosphere has been determined by comparison of measurements accomplished under air, argon and helium atmosphere. Reference samples have been produced and calibration curves have been determined, the results of LIBS measurements are compared with results from chemical analysis. Defining a limit for the intensity ratio of a calcium and a oxygen spectral line can reduce the influence of the heterogeneity of the material, so that only spectra with a high amount of cementitious material are evaluated. Depth profiles and spatial resolved sulfur distributions are presented measured on concrete cores originating from a highly sulfate contaminated clarifier.

Weritz, F.; Ryahi, S.; Schaurich, D.; Taffe, A.; Wilsch, G.

2005-08-01

192

Quantitative analysis of pharmaceutical products by laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

In this paper, the capabilities of laser-induced breakdown spectroscopy (LIBS) for rapid analysis of multi-component pharmaceutical tablets are illustrated using several examples. The atomic line emission from an element present only in a particular component of the tablet (for instance, emission of phosphorus from the drug, or of magnesium from the lubricant) enables the quantitative analysis of that component. It is also demonstrated that simple schemes can significantly improve the analytical performance of LIBS in this context. In particular, internal standardization with a carbon line was found to enable the correction of a matrix effect, apart from improving the precision of measurement. Furthermore, an improvement in the linearity of calibration was observed when the plasma continuum emission was used as internal standard. Finally, in the case of drugs containing halogen species (e.g. F or Cl), producing the plasma in a helium atmosphere caused a seven to eight-fold increase of the signal-to-background ratio, thus improving sensitivity. These data illustrate the strengths of LIBS for fast at-line assessment of the reliability of pharmaceutical manufacturing processes.

St-Onge, L.; Kwong, E.; Sabsabi, M.; Vadas, E. B.

2002-07-01

193

Quantitative methods for structural characterization of proteins based on deep UV resonance Raman spectroscopy.  

PubMed

Here we report on novel quantitative approaches for protein structural characterization using deep UV resonance Raman (DUVRR) spectroscopy. Specifically, we propose a new method combining hydrogen-deuterium (HD) exchange and Bayesian source separation for extracting the DUVRR signatures of various structural elements of aggregated proteins including the cross-beta core and unordered parts of amyloid fibrils. The proposed method is demonstrated using the set of DUVRR spectra of hen egg white lysozyme acquired at various stages of HD exchange. Prior information about the concentration matrix and the spectral features of the individual components was incorporated into the Bayesian equation to eliminate the ill-conditioning of the problem caused by 100% correlation of the concentration profiles of protonated and deuterated species. Secondary structure fractions obtained by partial least squares (PLS) and least squares support vector machines (LS-SVMs) were used as the initial guess for the Bayessian source separation. Advantages of the PLS and LS-SVMs methods over the classical least squares calibration (CLSC) are discussed and illustrated using the DUVRR data of the prion protein in its native and aggregated forms. PMID:20580825

Shashilov, Victor A; Sikirzhytski, Vitali; Popova, Ludmila A; Lednev, Igor K

2010-05-24

194

Non-invasive tissue temperature measurements based on quantitative diffuse optical spectroscopy (DOS) of water  

NASA Astrophysics Data System (ADS)

We describe the development of a non-invasive method for quantitative tissue temperature measurements using Broadband diffuse optical spectroscopy (DOS). Our approach is based on well-characterized opposing shifts in near-infrared (NIR) water absorption spectra that appear with temperature and macromolecular binding state. Unlike conventional reflectance methods, DOS is used to generate scattering-corrected tissue water absorption spectra. This allows us to separate the macromolecular bound water contribution from the thermally induced spectral shift using the temperature isosbestic point at 996 nm. The method was validated in intralipid tissue phantoms by correlating DOS with thermistor measurements (R = 0.96) with a difference of 1.1 ± 0.91 °C over a range of 28-48 °C. Once validated, thermal and hemodynamic (i.e. oxy- and deoxy-hemoglobin concentration) changes were measured simultaneously and continuously in human subjects (forearm) during mild cold stress. DOS-measured arm temperatures were consistent with previously reported invasive deep tissue temperature studies. These results suggest that DOS can be used for non-invasive, co-registered measurements of absolute temperature and hemoglobin parameters in thick tissues, a potentially important approach for optimizing thermal diagnostics and therapeutics.

Chung, S. H.; Cerussi, A. E.; Merritt, S. I.; Ruth, J.; Tromberg, B. J.

2010-07-01

195

[Quantitative determination of trace heavy metals in polluted soil by laser induced breakdown spectroscopy].  

PubMed

Based on laser induced breakdown spectroscopy data analysis, a quantitative determination method of elements was introduced. This method takes the advantage of Fourier analysis to study different part of the spectrum-white noise, thermal radiation and emission spectral lines. Through band-pass filter, emission spectral lines and most noise were separated, only a little white noise was missed. By calculated similarity between detected line and its corresponding unit characteristic line, convolution intensity was introduced to measure the detected line intensity. With Cu 324.75 nm as the analysis line and Ti 337.28 nm as the base line, the way of separating spectrum mentioned before was carried out to detect trace Cu pollution in soil. Results contained two bright spots. First, The correlation coefficient between Cu concentration and the spectral intensity was up to 0.997 9. Last but not the least, the detectability of Cu in soil was 44 mg x kg(-1), which is below the trace element thresholds for Class 2 soil used in the environmental quality standard for soil in China. At the same time, the relative error is always below 10%. Therefore the feasibility of this method for portable and instant detection of heavy metals in polluted soil was verified. PMID:21510402

Wu, Wen-Tao; Ma, Xiao-Hong; Zhao, Hua-Feng; Zheng, Ze-Ke; Zhang, Min; Liag, Yan-Biao

2011-02-01

196

Hypoxic encephalopathy after near-drowning studied by quantitative 1H-magnetic resonance spectroscopy.  

PubMed Central

Early prediction of outcome after global hypoxia of the brain requires accurate determination of the nature and extent of neurological injury and is cardinal for patient management. Cerebral metabolites of gray and white matter were determined sequentially after near-drowning using quantitative 1H nuclear magnetic resonance spectroscopy (MRS) in 16 children. Significant metabolite abnormalities were demonstrated in all patients compared with their age-matched normal controls. Severity of brain damage was quantified from metabolite concentrations and ratios. Loss of N-acetylaspartate, a putative neuronal marker, from gray matter preceded that observed in white matter and was more severe. Total creatine decreased, while lactate and glutamine/glutamate concentrations increased. Changes progressed with time after injury. A spectroscopic prognosis index distinguished between good outcome (n = 5) and poor outcome (n = 11) with one false negative (bad outcome after borderline MRS result) and no false positive results (100% specificity). The distinction was made with 90% sensitivity early (after 48 h) and became 100% later (by days 3 and 4). This compared with 50-75% specificity and 70-100% sensitivity based upon single clinical criteria. MRS performed sequentially in occipital gray matter provides useful objective information which can significantly enhance the ability to establish prognosis after near-drowning.

Kreis, R; Arcinue, E; Ernst, T; Shonk, T K; Flores, R; Ross, B D

1996-01-01

197

Fused glass sample preparation for quantitative laser-induced breakdown spectroscopy of geologic materials  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy is a powerful analytical method, but LIBS is subject to a matrix effect which can limit its ability to produce quantitative results in complex materials such as geologic samples. Various methods of sample preparation, calibration, and data processing have been attempted to compensate for the matrix effect and improve LIBS precision. This study focuses on sample preparation by comparing fused glass as a preparation for powdered material to the more commonly used method of pressing powder into pellets for LIBS analysis of major elements in complex geologic materials. Pelletizing powdered material is a common and convenient method for preparing samples but problems with the physical matrix brought on by inconsistencies in the homogeneity, density, and laser absorption, coupled with the chemical matrix problem lead to spectral peak responses that are not always consistent with the absolute concentration of representative elements. Twenty-two mineral and rock samples were analyzed for eight major oxide elements. Samples were prepared under both glass and pellet methods and compared for internal precision and overall accuracy. Fused glass provided a more consistent physical matrix and yielded more reliable peak responses in the LIBS analysis than did the pressed pellet preparation. Statistical comparisons demonstrated that the glass samples expressed stronger separability between different mineral species based on the eight elements than for the pressed pellets and showed better spot-to-spot repeatability. Regression models showed substantially better correlations and predictive ability among the elements for the glass preparation than did those for the pressed pellets.

Pease, Patrick

2013-05-01

198

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

199

Techniques for analysing ground-based UV-visible long-term BrO and NO2 observations for satellite validation and trend analysis  

Microsoft Academic Search

NIWA operates a network of zenith-sky viewing DOAS (Differential Optical Absorption Spec-troscopy) instruments to measure NO2 and BrO. The longest existing time series (1981 -present) of NO2 has been measured at Lauder (45oS), New Zealand and the trend of this long-term data set has been studied extensively. Here we present a summary of stratospheric NO2 trends observed at several Northern

Karin Kreher; Paul Johnston; Timothy Hay; Ben Liley; Alan Thomas; Monica Martinez-Aviles; Udo Friess; Greg Bodeker; Robyn Schofield; Michel van Roozendael

2010-01-01

200

UV-visible spectroscopic study of the reaction kinetics of methylpiperazine-modified poly(vinyl chloride)s for use as fixed-state proton carrier membranes  

Microsoft Academic Search

Aminated poly(vinyl chloride)s (AmPVCs) were synthesized for use as fixed-site proton carrier membranes. Reactions between PVC and methylpiperazine (MePIP) in dimethylformamide (DMF) were studied using UV-VIS spectroscopy over time, temperature, and in the presence of the catalyst, potassium fluoride (KF). Based on the spectra of AmPVCs in THF, the peak attributions were assigned and the extinction coefficients were calculated to

Anna R. Roudman; Robert P. Kusy

1998-01-01

201

Quantitative assessment of hydrocarbon contamination in soil using reflectance spectroscopy: a "multipath" approach.  

PubMed

Petroleum hydrocarbons are contaminants of great significance. The commonly used analytic method for assessing total petroleum hydrocarbons (TPH) in soil samples is based on extraction with 1,1,2-Trichlorotrifluoroethane (Freon 113), a substance prohibited to use by the Environmental Protection Agency. During the past 20 years, a new quantitative methodology that uses the reflected radiation of solids has been widely adopted. By using this approach, the reflectance radiation across the visible, near infrared-shortwave infrared region (400-2500 nm) is modeled against constituents determined using traditional analytic chemistry methods and then used to predict unknown samples. This technology is environmentally friendly and permits rapid and cost-effective measurements of large numbers of samples. Thus, this method dramatically reduces chemical analytical costs and secondary pollution, enabling a new dimension of environmental monitoring. In this study we adapted this approach and developed effective steps in which hydrocarbon contamination in soils can be determined rapidly, accurately, and cost effectively solely from reflectance spectroscopy. Artificial contaminated samples were analyzed chemically and spectrally to form a database of five soils contaminated with three types of petroleum hydrocarbons (PHCs), creating 15 datasets of 48 samples each at contamination levels of 50-5000 wt% ppm (parts per million). A brute force preprocessing approach was used by combining eight different preprocessing techniques with all possible datasets, resulting in 120 different mutations for each dataset. The brute force was done based on an innovative computing system developed for this study. A new parameter for evaluating model performance scoring (MPS) is proposed based on a combination of several common statistical parameters. The effect of dividing the data into training validation and test sets on modeling accuracy is also discussed. The results of this study clearly show that predicting TPH levels at low concentrations in selected soils at high precision levels is viable. Dividing a dataset into training, validation, and test groups affects the modeling process, and different preprocessing methods, alone or in combination, need to be selected based on soil type and PHC type. MPS was found to be a better parameter for selecting the best performing model than ratio of prediction to deviation, yielding models with the same performance but less complicated and more stable. The use of the "all possibilities" system proved to be mandatory for efficient optimal modeling of reflectance spectroscopy data. PMID:24160885

Schwartz, Guy; Ben-Dor, Eyal; Eshel, Gil

2013-11-01

202

Investigation of degenerate four-wave mixing and polarization spectroscopy for quantitative measurements in combustion environments  

NASA Astrophysics Data System (ADS)

The physics of degenerate four-wave mixing (DFWM) and polarization spectroscopy (PS) and their application for quantitative concentration measurements in gas-phase media have been investigated both theoretically and experimentally. The physics of the two techniques was studied theoretically by direct numerical integration (DNI) of the time-dependent density matrix equations. Polarization effects were included by incorporation of the Zeeman structure of the upper and lower energy levels, and molecular motion effects were included by solution of the density matrix equations for numerous velocity groups. The DNI calculations demonstrated that the DFWM signal penalty for crossed-polarized configurations is decreased when the resonance is saturated. This result was explained in terms of the coupling of the various Zeeman states during the DFWM interaction for specific polarization configurations. Using the DNI approach to study PS, the low-pump- intensity PS signal was shown to be very dependent on the ratio of Doppler broadening to collisional broadening when the Doppler width is greater than the collisional width. However, at saturating pump intensities, the line- center PS signal intensity becomes nearly independent of the collision rate when the collisional width is less than the Doppler linewidth. The application of DFWM and PS for quantitative concentration measurements was investigated experimentally by measuring lineshapes and signal intensities in well-characterized hydrogen/air flames. Resonances in the A2? +-X2? (0,0) band of hydroxyl (OH) were probed with both perturbative and saturating beam intensities. Hydroxyl number densities were calculated from the DFWM and PS signal intensities in a series of near-adiabatic flames at equivalence ratios ranging from 0.5 to 1.5. The use of saturating laser intensities minimized the effects of beam absorption and variation of the collisional dynamics, providing more accurate number density measurements. The saturated DFWM results and the saturated PS results were in excellent agreement with OH absorption measurements and equilibrium calculations of OH concentration. The polarization dependence of the P1(2) and R2(l) DFWM transitions was investigated, providing experimental confirmation that the signal penalties predicted by a perturbative treatment of DFWM can be much less when the resonances are saturated.

Reichardt, Thomas Andrew

203

Final Report: Investigation of Polarization Spectroscopy and Degenerate Four-Wave Mixing for Quantitative Concentration Measurements  

SciTech Connect

Laser-induced polarization spectroscopy (LIPS), degenerate four-wave mixing (DFWM), and electronic-resonance-enhanced (ERE) coherent anti-Stokes Raman scattering (CARS) are techniques that shows great promise for sensitive measurements of transient gas-phase species, and diagnostic applications of these techniques are being pursued actively at laboratories throughout the world. However, significant questions remain regarding strategies for quantitative concentration measurements using these techniques. The primary objective of this research program is to develop and test strategies for quantitative concentration measurements in flames and plasmas using these nonlinear optical techniques. Theoretically, we are investigating the physics of these processes by direct numerical integration (DNI) of the time-dependent density matrix equations that describe the wave-mixing interaction. Significantly fewer restrictive assumptions are required when the density matrix equations are solved using this DNI approach compared with the assumptions required to obtain analytical solutions. For example, for LIPS calculations, the Zeeman state structure and hyperfine structure of the resonance and effects such as Doppler broadening can be included. There is no restriction on the intensity of the pump and probe beams in these nonperturbative calculations, and both the pump and probe beam intensities can be high enough to saturate the resonance. As computer processing speeds have increased, we have incorporated more complicated physical models into our DNI codes. During the last project period we developed numerical methods for nonperturbative calculations of the two-photon absorption process. Experimentally, diagnostic techniques are developed and demonstrated in gas cells and/or well-characterized flames for ease of comparison with model results. The techniques of two-photon, two-color H-atom LIPS and three-laser ERE CARS for NO and C{sub 2}H{sub 2} were demonstrated during the project period, and nonperturbative numerical models of both of these techniques were developed. In addition, we developed new single-mode, injection-seeded optical parametric laser sources (OPLSs) that will be used to replace multi-mode commercial dye lasers in our experimental measurements. The use of single-mode laser radiation in our experiments will increase significantly the rigor with which theory and experiment are compared.

Robert P. Lucht

2005-03-09

204

Clustering and training set selection methods for improving the accuracy of quantitative laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

We investigated five clustering and training set selection methods to improve the accuracy of quantitative chemical analysis of geologic samples by laser induced breakdown spectroscopy (LIBS) using partial least squares (PLS) regression. The LIBS spectra were previously acquired for 195 rock slabs and 31 pressed powder geostandards under 7 Torr CO2 at a stand-off distance of 7 m at 17 mJ per pulse to simulate the operational conditions of the ChemCam LIBS instrument on the Mars Science Laboratory Curiosity rover. The clustering and training set selection methods, which do not require prior knowledge of the chemical composition of the test-set samples, are based on grouping similar spectra and selecting appropriate training spectra for the partial least squares (PLS2) model. These methods were: (1) hierarchical clustering of the full set of training spectra and selection of a subset for use in training; (2) k-means clustering of all spectra and generation of PLS2 models based on the training samples within each cluster; (3) iterative use of PLS2 to predict sample composition and k-means clustering of the predicted compositions to subdivide the groups of spectra; (4) soft independent modeling of class analogy (SIMCA) classification of spectra, and generation of PLS2 models based on the training samples within each class; (5) use of Bayesian information criteria (BIC) to determine an optimal number of clusters and generation of PLS2 models based on the training samples within each cluster. The iterative method and the k-means method using 5 clusters showed the best performance, improving the absolute quadrature root mean squared error (RMSE) by ~ 3 wt.%. The statistical significance of these improvements was ~ 85%. Our results show that although clustering methods can modestly improve results, a large and diverse training set is the most reliable way to improve the accuracy of quantitative LIBS. In particular, additional sulfate standards and specifically fabricated analog samples with Mars-like compositions may improve the accuracy of ChemCam measurements on Mars. Refinement of the iterative method, modifications of the basic k-means clustering algorithm, and classification based on specifically selected S, C and Si emission lines may also prove beneficial and merit further study.

Anderson, Ryan B.; Bell, James F., III; Wiens, Roger C.; Morris, Richard V.; Clegg, Samuel M.

2012-04-01

205

[Localized nuclear magnetic resonance spectroscopy in vivo. Physical principles and quantitative problems].  

PubMed

Recent technological developments extended the use of nuclear magnetic resonance to clinical imaging (MRI), as well as to in vivo metabolic studies on tissues and organs by means of localized spectroscopy (MRS). The quantitative determination of absolute metabolic concentrations by in vivo MRS still represents a challenge for technological efforts and biochemical investigations. In fact, the different methodologies today available for spectral acquisition from localized regions within a body organ or pathological lesion should ideally lead to a complete suppression of signals from surrounding tissues, without any appreciable signal loss from the volume of interest. Accurate assessment of deviations of the real from the ideal case represents an essential requirement for either relative or absolute quantification of in vivo localized MR spectra. A review will be presented of the most utilized MRS methodologies, together with a discussion on their potentialities and limitations. Techniques have been classified according to the use of either r.f. (B1) and/or static magnetic field (B0) gradients. The last session will be devoted to the presentation of some results obtained in our laboratory on the use of a particular test-object (constructed at the Deft Institute of Technology) for assessing signal localization efficiency provided by a surface coil in a small scale MRS/MRI equipment (for in vivo biochemical studies on small animals). The surface coil was used in conjunction with a number of sequence (t1-90 degrees-acq; 1-D "chemical shift imaging"; "depth") of either square or adiabatic r.f. pulses. The results allow the selection, on a quantitative basis, of the most appropriate pulse sequence(s) to be used for metabolic studies on superficial experimental tumours (implanted s.c. in small animals), according to the mean area and thickness of the neoplastic lesion. The latter parameters can be non-invasively assessed by previous MRI analysis of the tumour. This study was carried out in the frame of the EC COMAC-BME Concerted Research Project on Tissue Characterization by MRS and MRI. PMID:1820740

Canese, R; Podo, F

1991-01-01

206

Quantitative Determination of Dielectric Thin-Film Properties Using Infrared Emission Spectroscopy  

SciTech Connect

We have completed an experimental study to investigate the use of infrared emission spectroscopy (IRES) for the quantitative analysis of borophosphosilicate glass (BPSG) thin films on silicon monitor wafers. Experimental parameters investigated included temperatures within the range used in the microelectronics industry to produce these films; hence the potential for using the IRES technique for real-time monitoring of the film deposition process has been evaluated. The film properties that were investigated included boron content, phosphorus content, film thickness, and film temperature. The studies were conducted over two temperature ranges, 125 to 225 *C and 300 to 400 *C. The later temperature range includes realistic processing temperatures for the chemical vapor deposition (CVD) of the BPSG films. Partial least squares (PLS) multivariate calibration methods were applied to spectral and film property calibration data. The cross-validated standard errors of prediction (CVSEP) fi-om the PLS analysis of the IRES spectraof21 calibration samples each measured at 6 temperatures in the 300 to 400 "C range were found to be 0.09 wt. `?40 for B, 0.08 wt. `%0 for P, 3.6 ~m for film thickness, and 1.9 *C for temperature. By lowering the spectral resolution fi-om 4 to 32 cm-l and decreasing the number of spectral scans fi-om 128 to 1, we were able to determine that all the film properties could be measured in less than one second to the precision required for the manufacture and quality control of integrated circuits. Thus, real-time in-situ monitoring of BPSG thin films formed by CVD deposition on Si monitor wafers is possible with the methods reported here.

Franke, J.E.; Haaland, D.M.; Niemczyk, T.M.; Zhang, S.

1998-10-14

207

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

208

Exploring the potential of Raman and resonance Raman spectroscopy for quantitative analysis of duplex DNA  

NASA Astrophysics Data System (ADS)

Advances in DNA microarray fabrication technologies, expanding probe libraries, and new bioinformatics methods and resources have firmly established array-based techniques as mainstream bioanalytical tools and the application space is proliferating rapidly. However, the capability of these tools to yield truly quantitative information remains limited, primarily due to problems inherent to the use of fluorescence imaging for reading the hybridized arrays. The obvious advantages of fluorescence are the unrivaled sensitivity and simplicity of the instrumentation. There are disadvantages of this approach, however, such as difficulties in achieving optimal labeling of targets and reproducible signals (due to quenching, resonance energy transfer, photobleaching effects, etc.) that undermine precision. We are exploring alternative approaches, based mainly on Raman and resonance Raman spectroscopy, that in principle permit direct analysis of structural differences between hybridized and unhybridized probes, thereby eliminating the need for labeling the target analytes. We report here on the status of efforts to evaluate the potential of these methods based on a combination of measured data and simulated experiments involving short (12-mer) ssDNA oligomer probes with varying degrees of hybridized target DNA. Preliminary results suggest that it may be possible to determine the fraction of duplex probes within a single register on a DNA microarray from 100% down to 10% (or possibly less) with a precision of +/-2 5%. Details of the methods used, their implementation, and their potential advantages and limitations are presented, along with discussion of the utility of using 2DCOS methods to emphasize small spectral changes sensitive to interstrand H bonding, backbone flexibility, hypochromicity due to base-stacking in duplex structures and solvation effects.

Schulze, H. G.; Bass, A.; Addison, C.; Hughesman, C.; So, A. P.; Haynes, C. A.; Blades, M. W.; Turner, R. F. B.

2005-09-01

209

Quantitative nanoscale water mapping in frozen-hydrated skin by low-loss electron energy-loss spectroscopy  

Microsoft Academic Search

Spatially resolved low-loss electron energy-loss spectroscopy (EELS) is a powerful method to quantitatively determine the water distribution in frozen-hydrated biological materials at high spatial resolution. However, hydrated tissue, particularly its hydrophilic protein-rich component, is very sensitive to electron radiation. This sensitivity has traditionally limited the achievable spatial resolution because of the relatively high noise associated with low-dose data acquisition. We

Sergey Yakovlev; Manoj Misra; Shanling Shi; Emre Firlar; Matthew Libera

2010-01-01

210

Discrimination of edible oil products and quantitative determination of their iodine value by Fourier transform near-infrared spectroscopy  

Microsoft Academic Search

This work demonstrates the application of partial least squares (PLS) analysis as a discriminant as well as a quantitative\\u000a tool in the analysis of edible fats and oils by Fourier transform near-infrared (FT-NIR) spectroscopy. Edible fats and oils\\u000a provided by a processor were used to calibrate a FT-NIR spectrometer to discriminate between four oil formulations and to\\u000a determine iodine value

Hui Li; F. R. van de Voort; A. A. Ismail; J. Sedman; R. Cox; C. Simard; H. Buijs

2000-01-01

211

Quantitative measurements of O 2 b ? X(2,1,0?0) bands by using cavity ring-down spectroscopy  

Microsoft Academic Search

Quantitative measurements of individual rotational line intensities of molecular oxygen are made for the (0?0), (1?0), (2?0) bands of the b1?g+?X3?g? transition using highly sensitive cavity ring-down spectroscopy (CRDS). The absorption profiles of six rotational lines of the three bands of O2 are measured under pressures up to 1 atm. Corrections have been made to eliminate the effect of laser

Shucheng Xu; Dongxu Dai; Jinchun Xie; Guohe Sha; Cunhao Zhang

1999-01-01

212

Development and validation of UV-Visible spectrophotometric baseline manipulation methodology for simultaneous analysis of drotraverine and etoricoxib in pharmaceutical dosage forms  

PubMed Central

Introduction: A simple, economical, precise, and accurate new UV spectrophotometric baseline manipulation methodology for simultaneous determination of drotaverine (DRT) and etoricoxib (ETR) in a combined tablet dosage form has been developed. Materials and Methods: The method is based on baseline manipulation (difference) spectroscopy where the amplitudes at 274 and 351 nm were selected to determine ETR and DRT, respectively, in combined formulation and methanol was used as solvent. Both the drugs obey Beer's law in the concentration ranges of 4–20 ?g/mL for DRT and 4.5–22.5 ?g/mL for ETR. Results: The results of analysis have been validated statistically and recovery studies confirmed the accuracy and reproducibility of the proposed method which were carried out by following the ICH guidelines. Conclusion: It has been concluded that a new simple and accurate UV spectrophotometric baseline manipulation method was developed for simultaneous do not declare DRT and ETR in a combined tablet dosage form has been developed.

Choudhari, Vishnu P.; Parekar, Sanket R.; Chate, Subhash G.; Bharande, Pradeep D.; Kuchekar, Bhanudas S.

2011-01-01

213

Quantitative analysis of liquids from aerosols and microdrops using laser induced breakdown spectroscopy.  

PubMed

Laser induced breakdown spectroscopy (LIBS) is shown to be capable of low volume (90 pL) quantitative elemental analysis of picogram amounts of dissolved metals in solutions. Single-pulse and collinear double-pulse LIBS were investigated using a 532 nm dual head laser coupled to a spectrometer with an intensified charge coupled device (CCD) detector. Aerosols were produced using a micronebulizer, conditioned inside a concentric spray chamber, and released through an injector tube with a diameter of 1 mm such that a LIBS plasma could be formed ~2 mm from the exit of the tube. The emissions from both the aerosols and a single microdrop were then collected with a broadband high resolution spectrometer. Multielement calibration solutions were prepared, and continuing calibration verification (CCV) standards were analyzed for both aerosol and microdrop systems to calculate the precision, accuracy, and limits of detection for each system. The calibration curves produced correlation coefficients with R(2) values > 0.99 for both systems. The precision, accuracy, and limit of detection (LOD) determined for aerosol LIBS were averaged and determined for the emission lines of Sr II (421.55 nm), Mg II (279.80 nm), Ba II (493.41 nm), and Ca II (396.84 nm) to be ~3.8% RSD, 3.1% bias, 0.7 ?g/mL, respectively. A microdrop dispenser was used to deliver single drops containing 90 pL into the space where a LIBS plasma was generated with a focused laser pulse. In the single drop microdrop LIBS experiment, the analysis of a single drop, containing a total mass of 45 pg, resulted in a precision of 13% RSD and a bias of 1% for the Al I (394.40 nm) emission line. The absolute limits of detection of single drop microdrop LIBS for the emission lines Al I (394.40 nm) and Sr II (421.5 nm) were approximately 1 pg, and Ba II (493.41 nm) produced an absolute detection limit of approximately 3 pg. Overall, the precision, accuracy, and absolute LOD determined for single microdrop LIBS resulted in a typical performance of ~14% RSD, 6% bias, and 1 pg for the elements Sr II (421.55 nm), Al I(394.40 nm), Mg II (279.80), and Ba II(493.41 nm). PMID:22283515

Cahoon, Erica M; Almirall, Jose R

2012-02-10

214

Subcortical Ischemic Vascular Dementia: Assessment with Quantitative MR Imaging and 1H MR Spectroscopy  

Microsoft Academic Search

METHODS: Patients with dementia and lacunes (n 5 11), cognitive impairment and lacunes (n 5 14), and dementia without lacunes (n 5 18) and healthy age-matched control volunteers (n 5 20) underwent MR imaging and 1H MR spectroscopy. 1H MR spectroscopy data were coan- alyzed with coregistered segmented MR images to account for atrophy and tissue composition. RESULTS: Compared with

Aristides A. Capizzano; Norbert Schuff; Diane L. Amend; Jody L. Tanabe; David Norman; Andrew A. Maudsley; William Jagust; Helena C. Chui; George Fein; Mark R. Segal; Michael W. Weiner

215

Quantitative Analysis of the TWT Cathode Impregnants Using Flame Emission Spectroscopy.  

National Technical Information Service (NTIS)

Flame emission spectroscopy (FES) is demonstrated for the determination of barium, calcium, and aluminum concentrations in barium calcium aluminate dispenser cathode impregnants. The procedure consists of dissolving the impregnant in 0.5M to 2M hydrochlor...

R. A. Lipeles

1987-01-01

216

Quantitative determination of atractylon in Atractylodis Rhizoma and Atractylodis Lanceae Rhizoma by 1H-NMR spectroscopy.  

PubMed

(1)H-NMR spectroscopy was successfully applied to the quantitative determination of atractylon in Atractylodis Rhizoma (dried rhizomes of Atractylodes ovata and A. japonica) and Atractylodis Lanceae Rhizoma (dried rhizomes of Atractylodes lancea and A. chinensis). The analysis was carried out by comparing the integral of the H-12 singlet signal of atractylon, which was well separated in the range of delta 6.95-7.05 ppm in the NMR spectrum, with the integral of a hexamethyldisilane (HMD) signal at delta 0 ppm. The atractylon contents obtained by the (1)H-NMR spectroscopy were consistent with those obtained by the conventional HPLC analysis. The present method requires neither reference compounds for calibration curves nor sample pre-purification. It also allows simultaneous determination of multiple constituents in a crude extract. Thus, it is applicable to chemical evaluation of crude drugs as a powerful alternative to various chromatographic methods. PMID:20165926

Hasada, Keiko; Yoshida, Takamitsu; Yamazaki, Takeshi; Sugimoto, Naoki; Nishimura, Tetsuji; Nagatsu, Akito; Mizukami, Hajime

2010-02-19

217

[Quantitative analysis of protein concentration by absorption peak integration method of UV spectroscopy--taking alkaline phosphatase as an example].  

PubMed

Adsorption of alkaline phosphatase (APase) on minerals (goethite, montmorillonite) and sediments from Taihu Lake was studied. However, the concentration of alkaline phosphatase in the supernatant cannot be analyzed by the adsorption at 280 nm due to that the UV spectroscopy was changed. Quantitative analysis of alkaline phosphatase in the supernatant by the absorption peak (252-305 nm) integration method of UV spectroscopy was developed. This method determined the concentrations of alkaline phosphatase well. Compared to the results of Bradford, the absorption peak integration method can determine the concentrations of supernatant fast, conveniently, and accurately. This method can also be applied to other protein solution analysis and similar experiments. The drawbacks of traditional single wavelength method (280nm) were overcome to some extent based on the method of absorption peak integration. PMID:24059187

Zhu, Yuan-Rong; Wu, Feng-Chang; Lin, Ying

2013-07-01

218

A Semi-Quantitative Analysis of Essential Micronutrient in Folium Lycii Using Laser-Induced Breakdown Spectroscopy Technique  

NASA Astrophysics Data System (ADS)

In this paper, the capabilities of laser-induced breakdown spectroscopy (LIBS) for rapid analysis to multi-component plant are illustrated using a 1064 nm laser focused onto the surface of folium lycii. Based on homogeneous plasma assumption, nine of essential micronutrients in folium lycii are identified. Using Saha equation and Boltzmann plot method electron density and plasma temperature are obtained, and their relative concentration (Ca, Mg, Al, Si, Ti, Na, K, Li, and Sr) are obtained employing a semi-quantitative method.

Sun, Duixiong; Su, Maogen; Dong, Chenzhong; Zhang, Dacheng; Ma, Xinwen

2010-08-01

219

Semi-quantitative surface analysis of Mt. St. Helens Ash by X-ray photoelectron spectroscopy (XPS)  

NASA Astrophysics Data System (ADS)

A sample of Mt. St. Helens tephra and USGS andesite rock standard (AGV-1) were analyzed by X-ray photoelectron spectroscopy (XPS). The results indicate major element surface analysis on powdered multicomponent samples (such as geological specimens) can be performed semi-quantitatively using an equation that relates XPS peak intensity with atomic surface density. The surface compositions found by XPS are in good agreement with bulk X-ray fluorescence analysis (XRF). It is interesting to note that XPS analysis of this volcanic ash did not reveal a surface enrichment of chlorine or sulphur and only trace fluorine although these volatile elements are normally abundant in volcanic gases.

Brown, J. R.; Fyfe, W. S.; Bancroft, G. M.

220

Quantitative and qualitative analysis of fluorescent substances and binary mixtures by use of shifted excitation Raman difference spectroscopy  

NASA Astrophysics Data System (ADS)

Shifted Excitation Raman Difference Spectroscopy (SERDS) implemented with two wavelength-stabilized laser diodes with fixed wavelength separation is discussed as an effective method for dealing with the effects of fluorescence in Raman spectroscopic analysis. In this presentation we discuss the results of both qualitative and quantitative SERDS analysis of a variety of strongly fluorescing samples, including binary liquid mixtures. This application is enabled by the Volume Bragg Grating® (VBG®) technology, which allows manufacturing of compact low-cost high-power laser sources, suitable for extending the SERDS methodology to portable Raman spectrometers.

Volodin, Boris L.; Dolgy, Sergei; Lieber, Chad; Wu, Huawen; Yang, William

2013-03-01

221

Monitoring of Streptomyces peucetius cultivations using FTIR/ATR spectroscopy and quantitative models based on library type data.  

PubMed

Cultivations of Streptomyces peucetius in two types of medium were monitored on-line using a Fourier transform infrared (FTIR) spectrometer combined with an attenuated total reflection probe. The quantitative measurements of the glucose, starch and acetate concentrations were implemented using partial least squares calibration models. These were regressed on spectral and concentration information obtained by adding together single constituent spectra of the main constituents in the medium according to a full factorial design. The accuracy achieved was considered to be satisfactory, with an average root mean square error of prediction of 1.5 g/l for glucose and 0.25 g/l for acetate. The methodology used is considered to be a rapid technique for generation of calibration data, and a step towards the use of library type data for calibration purposes in quantitative FTIR spectroscopy applications in bioprocesses. PMID:23242495

Dahlbacka, John; Kiviharju, Kristiina; Eerikäinen, Tero; Fagervik, Kaj

2012-12-15

222

Quantitative characterization of the mesothelioma-inducing erionite series minerals by transmission electron microscopy and energy dispersive spectroscopy.  

PubMed

Air-collected erionite series minerals from Cappadocia region of Turkey were characterized quantitatively by using transmission electron microscopy (TEM) equipped with energy dispersive spectroscopy (EDS). Field emission scanning electron microscopy aided identification of fibrous minerals. Quantitative characterization guidelines for positive identification of erionites proposed by Dogan and Dogan (2008) was applied and the modified balance error formula (E%<10) and Mg-content test <0.80 were performed for each analysis. Erionite species computation showed that the mineral is erionite-K and a mean chemical formula is proposed based upon the TEM-EDS results. Among the 60 analyses, 11 passed E% test (18.3%), 33 passed Mg-content test (55.0%), and only 3 passed both E% and Mg-content tests (5.0%). This shows difficulty of quantitative characterization of the erionite series minerals. However, as erionite is the most carcinogenic mineral known and is classified by IARC as a Group-I (human) carcinogen, it requires special attention from the mineralogical community to help establish its true mineralogical properties. Quantitatively characterized erionite data are very scarce in literature. Correctly identified erionite mineral types will be useful to medical researchers in their search to find a possible cure for the deadly disease of mesothelioma. PMID:21866558

Dogan, Meral

2011-08-22

223

Quantitative Measurement of Superoxide Generation and Oxygen Consumption from Leukocytes Using Electron Paramagnetic Resonance Spectroscopy  

Microsoft Academic Search

In view of the important role of superoxide in cellular injury, there has been a great need for methods suitable for quantitation of superoxide production from cells. Previous methods have had limited sensitivity or specificity as well as problems with side reactions in cellular systems. Recently, we have shown that the new spin trap 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide has ideal properties for quantitative

Valerie Roubaud; Sornampillai Sankarapandi; Periannan Kuppusamy; Paul Tordo; Jay L. Zweier

1998-01-01

224

Quantitative Raman spectroscopy as a tool to study the kinetics and formation mechanism of carbonates.  

PubMed

We have carried out a systematic study of abiotic precipitation at different temperatures of several Mg and Ca carbonates (calcite, nesquehonite, hydrocalcite) present in carbonaceous chondrites. This study highlights the capability of Raman spectroscopy as a primary tool for performing full mineralogical analysis. The precipitation reaction and the structure of the resulting carbonates were monitored and identified with Raman spectroscopy. Raman spectroscopy enabled us to confirm that the precipitation reaction is very fast (minutes) when Ca(II) is present in the solution, whereas for Mg(II) such reactions developed at rather slow rates (weeks). We also observed that both the composition and the reaction mechanisms depended on temperature, which might help to clarify several issues in the fields of planetology and geology, because of the environmental implications of these carbonates on both terrestrial and extraterrestrial objects. PMID:23896294

Bonales, L J; Muñoz-Iglesias, V; Santamaría-Pérez, D; Caceres, M; Fernandez-Remolar, D; Prieto-Ballesteros, O

2013-07-09

225

Photochemical formation of chromium (V) in dichromated materials: a quantitative and comparative approach  

NASA Astrophysics Data System (ADS)

We have been working on dichromated photosensitive materials for several years. After investigating the photochemical process in various systems, it appears that the chemical structure of the polymeric matrix plays an essential role in the progress of the reaction that takes place upon irradiation by the laser beams. If the primary photochemical process is always the electron transfer from the matrix to the metallic cation giving rise to chromium (V) and a macroradical, the fate of chromium (V) in the system strongly depends on the chemical structure of the polymer. In dichromated poly(acrylic acid) DCPAA, chromium (V) is an unstable species only detectably by ESR spectroscopy upon irradiation: it disappears after stopping the irradiation very fast. On the contrary, chromium (V) is surprisingly stable in poly(vinyl alcohol) and in gelatin. The first spectral evolution corresponds to the only reduction of chromium (VI) into chromium (V) as evidenced by the presence of an isosbestic point. The subsequent reduction of chromium (V) is a very slow process: the complete transformation into chromium (III) is only achieved after several days. As a result, we were able to estimate the UV-visible spectrum of chromium (V) in the matrix and for the first time, it was possible to quantitatively follow the formation of this species and to draw some conclusion about the complexation sites in gelatin.

Bolte, Michele; Pizzocaro, Christine; Lafond, Christophe

1998-09-01

226

Quantitative solid-phase microextraction (SPME)-Raman spectroscopy for the detection of trace organics in water.  

PubMed

Solid-phase microextraction (SPME) was used along with Raman spectroscopy to quantify the partitioning of trace organics into polydimethylsiloxane (PDMS) matrices. PDMS has previously been utilized with SPME-Raman to pre-concentrate trace benzene, toluene, ethyl-benzene, and xylene fuel components from contaminated water, thereby enhancing detected Raman signals. Here, we show that SPME can increase Raman signals more than two orders of magnitude for the compounds investigated. We also demonstrate the quantitative features of SPME-Raman by estimating PDMS-organic partition coefficients for benzene [log(K) = 1.90 ± 10] and toluene [log(K) = 2.35 ± 20] by using linear regression fits in the dilute limit of concentrations. The K values obtained are within the range of values obtained with other quantitative SPME techniques. The method was also used to characterize quinoline, a pyridine-based organic, which yielded reasonable K values [log(K) = 1.20 ± 20]. Combining PDMS-based SPME with a technique such as Raman spectroscopy potentially enhances optical detection methods used in microfluidic systems, wherein PDMS is a common material of construction. PMID:23231913

Nwaneshiudu, Ikechukwu C; Yu, Qiuming; Schwartz, Daniel T

2012-12-01

227

Quantitative zinc speciation in soil with XAFS spectroscopy: evaluation of iterative transformation factor analysis  

Microsoft Academic Search

We employed a combination of selective sequential extractions and bulk XAFS spectroscopy, and extracted spectral XAFS components and their concentrations by iterative transformation factor analysis (ITFA), in order to determine the Zn speciation in a smelter-contaminated, acidic soil. We compared the speciation by ITFA with one we performed earlier using principal component analysis and linear combination fit. ITFA identified 4

A. C. Scheinost; A. Rossberg; M. Marcus; S. Pfister; R. Kretzschmar

2005-01-01

228

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

Microsoft Academic Search

The unambiguous identification and quantification of hazardous materials is of increasing importance in many sectors such as waste disposal, pharmaceutical manufacturing, and environmental protection. One particular problem in waste disposal and chemical manufacturing is the identification of solvents into chlorinated or non-chlorinated. In this work we have used Raman spectroscopy as the basis for a discrimination and quantification method for

Jennifer Conroy; Alan G. Ryder; Marc N. Leger; Kenneth Hennessey; Michael G. Madden

229

The Quantitative Determination of Bis-Phenol Antioxidant Additives in Petroleum Oils by Infrared Spectroscopy.  

National Technical Information Service (NTIS)

For the determining bis-phenolic antioxidants in petroleum oils by infrared spectroscopy, the bands corresponding to the hydroxyle groups are convenient as analytical bands, i.e., 3496/cm for 2,2-methylene-bis (4-methyl-6-tert-butylphenol), 3435/cm for 2,...

A. A. Kadushin S. Korchek

1968-01-01

230

Reliable and fast quantitative analysis of active ingredient in pharmaceutical suspension using Raman spectroscopy  

Microsoft Academic Search

The concentration of acetaminophen in a turbid pharmaceutical suspension has been measured successfully using Raman spectroscopy. The spectrometer was equipped with a large spot probe which enabled the coverage of a representative area during sampling. This wide area illumination (WAI) scheme (coverage area 28.3mm2) for Raman data collection proved to be more reliable for the compositional determination of these pharmaceutical

Seok Chan Park; Minjung Kim; Jaegeun Noh; Hoeil Chung; Youngah Woo; Jonghwa Lee; Mark S. Kemper

2007-01-01

231

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

232

[Usefulness of quantitative H-MR spectroscopy for the differentiation between radiation necrosis and recurrence of anaplastic oligodendroglioma].  

PubMed

We report a case, in which quantitative 1H-MR spectroscopy (MRS) was useful for the differentiation between radiation necrosis and a recurrent tumor. The present case is a 44-year-old man who underwent the subtotal removal of a mass lesion in the left frontal lobe. The histological diagnosis was anaplastic oligodendroglioma (WHO grade III). Postoperatively, a fractionated radiotherapy (total 64Gy) and chemotherapy were performed. MRI after the radiotherapy showed no contrast enhancing lesion. MRI, 5 years after the radiotherapy, showed a growing enhancing lesion and a T1 hypointensity lesion without enhancement, both of which indicated a recurrent tumor. MR spectroscopy was performed for the differential diagnosis of these lesions. The spectrum was acquired by the point resolved spectroscopy (PRESS) method by TR/TE=2,000 ms/68 ms, 136 ms, and 272 ms and evaluated with peak pattern and quantification value of metabolite. MRS of the enhancing lesion demonstrated a decrease of the Choline-containing compounds (Cho) concentration, disappearance of N-acetylaspartate (NAA), decrease of Creatine/ Phosphocreatine (t-Cr) and presence of Lipids (Lip) and Lactate (Lac), all of which are characteristic finding of a radiation necrosis. The histological diagnosis of this lesion showed evidence also of radiation necrosis. On the other hand, MRS of the T1 hypointensity lesion without enhancement showed, a marked high peak of the Cho concentration, which is characteristic for a recurrent tumor. The histological findings of this lesion showed a diffuse proliferation of recurrent tumor cells. Quantitative 1H-MRS is a useful tool for the differentiation between radiation necrosis and recurrent tumors. PMID:21512199

Isobe, Tomonori; Akutsu, Hiroyoshi; Yamamoto, Tetsuya; Shiigai, Masanari; Masumoto, Tomohiko; Nakai, Kei; Takano, Shingo; Anno, Izumi; Matsumura, Akira

2011-05-01

233

The quantitative monitoring of mechanochemical reaction between solid L-tartaric acid and sodium carbonate monohydrate by terahertz spectroscopy  

NASA Astrophysics Data System (ADS)

The solid-state reaction of chiral tartaric acid and alkali carbonate was studied by terahertz time-domain spectroscopy (THz-TDS). The sodium tartrate dihydrate was synthesized with high efficiency by mechanical grinding in the solid-state without waste that is particularly sustainable and environmentally benign. Distinct THz absorptions were observed for reactants and products. It indicates that THz spectroscopy is sensitive to different materials and crystal structures. The characteristic THz absorption peak at 1.09 THz of L (+)-Tartaric acid was selected for quantitative analysis. The reaction kinetics could be expressed by the Second-order equation and the Jander equation, which is consistent with a three-dimensional diffusion mechanism. The combination of multi-techniques including synchrotron radiation X-ray powder diffraction (SRXRPD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) was used to investigate the grinding process and presented supporting evidences. The results demonstrate that THz spectroscopy technique has great potential applications in process monitoring and analysis in pharmaceutical and chemical synthesis industry.

Liu, Xiaohong; Liu, Guifeng; Zhao, Hongwei; Zhang, Zengyang; Wei, Yongbo; Liu, Min; Wen, Wen; Zhou, Xingtai

2011-11-01

234

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 4000-400cm(-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

2013-07-23

235

Rapid and quantitative detection of ethanol proportion in ethanol–gasoline mixtures by Raman spectroscopy  

Microsoft Academic Search

The paper reports a Raman spectral in-situ detection technique to measure the ethanol proportion in an ethanol–gasoline mixture rapidly and quantitatively. The transformed information of Raman spectra for different mixtures of gasoline and ethanol have been observed and recorded. The relative intensity ratio of two typical Raman peaks for ethanol and gasoline satisfies a linear relation with a variation in

Qing Ye; Qinfeng Xu; Yongai Yu; Ronghui Qu; Zujie Fang

2009-01-01

236

[Quantitative analysis of surface composition of polypropylene blends using attenuated total reflectance FTIR spectroscopy].  

PubMed

The surface composition and structure of solid organic polymers influence many of their properties and applications. Oligomers such as poly(ethylene glycol) (PEG), poly(methyl methacrylate) (PMMA) poly(butyl methacrylate) (PBMA) and their graft copolymers of polybutadiene and polypropylene were used as the macromolecular surface modifiers of polypropylene. The compositions on surface and in bulk of the polypropylene (PP) blends were determined quantitatively using attenuated total reflectance FTIR spectroscopic (ATR-FTIR) technique with a variable-angle multiple-reflection ATR accessory and FTIR measurements, respectively. By validating by Lambert-Beer law, 1103 and 1733 cm(-1) can be used to represent modifiers characteristic absorbance band to determine quantitatively the surface composition of modifiers including poly(ethylene glycol) and carbonyl segment in PP blends, respectively. The determination error can be effectively eliminated by calibrating wavelength and using absorption peak area ratio as the calibrating basis for the quantitative analysis. To minimize the effect of contact between the polymer film and the internal reflection element on the results of absolute absorbance, the technique of "band ratioing" was developed, and it was testified that the error of the peak area ratios of interest can be reduced to 5% or below, which was suitable for ATR-FTIR used as a determining quantitative tool for surface composition. The working curves were then established and used to calculate the composition of the responding functional groups in the film surface of the PP blends. The depth distribution of modifiers on the surface of blend films also can be determined by changing the incident angle of interest on the basis of the equation of the depth of penetration of the excursion wave in ATR spectra. The results indicated that ATR-FTIR can be used to determine quantitatively the surface composition and distribution of modifiers with reproducible and reliable measurement results. PMID:18975806

Chen, Han-jia; Zhu, Ya-fei; Zhang, Yi; Xu, Jia-rui

2008-08-01

237

A semi-quantitative standard-less analysis method for laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

We report on recently developed analytical software to model laser-induced breakdown spectroscopy emission spectra and predict sample composition using a proposed calibration-free algorithm. The model uses a database of atomic emission lines to create a theoretical emission spectrum for selected elements using defined plasma parameters. The resulting theoretical spectrum is fitted to experimental data obtained from a laser-induced breakdown spectroscopy instrument comprising of four compact spectrometers that image the plasma emission. Elemental concentrations are obtained by comparing observed and predicted spectra while varying the plasma temperature and relative elemental concentrations. The use of the model for analysis of major elements in bauxites, brass and mineral samples as well as the analysis of laboratory air is demonstrated. For the majority of elements investigated agreement within 25% is achieved between estimated and certified values.

Yaroshchyk, Pavel; Body, Doug; Morrison, Richard J. S.; Chadwick, Bruce L.

2006-02-01

238

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

239

Quantitative Diffuse Reflectance and Fluorescence Spectroscopy: A Tool to Monitor Tumor Physiology In Vivo  

PubMed Central

This study demonstrates the use of optical spectroscopy for monitoring tumor oxygenation and metabolism in response to hyperoxic gas breathing. Hemoglobin saturation and redox ratio were quantified for a set of 14 and 9 mice, respectively, measured at baseline and during carbogen breathing (95% O2, 5% CO2). In particular, significant increases in hemoglobin saturation and fluorescence redox ratio were observed upon carbogen breathing. These data were compared to that obtained concurrently using an established invasive technique, the OxyLite pO2 system, which also showed a significant increase in pO2. It was found that the direction of changes were generally the same between all of the methods, but that the OxyLite system was much more variable in general, suggesting that optical techniques may provide a better assessment of global tumor physiology. Optical spectroscopy measurements are demonstrated to provide a reliable, reproducible indication of changes in tumor physiology in response to physiologic manipulation.

Palmer, Gregory M.; Viola, Ronald J.; Schroeder, Thies; Yarmolenko, Pavel S.; Dewhirst, Mark W.; Ramanujam, Nirmala

2009-01-01

240

Quantitative analysis of ?-pinene and ?-myrcene in mastic gum oil using FT-Raman spectroscopy  

Microsoft Academic Search

?-Pinene and ?-myrcene are compounds that are contained in mastic gum in high concentrations. The ?-myrcene percentage determines the marketability of mastic gums. The chemical composition of mastic gum oil of a representative resin quality was evaluated by gas chromatography–mass spectrometry (GC–MS) technique. FT-Raman spectroscopy, based on band intensity measurements, was used for the determination of ?-pinene and ?-myrcene content

D. Daferera; C. Pappas; P. A. Tarantilis; M. Polissiou

2002-01-01

241

In situ monitoring by quantitative Raman spectroscopy of alcoholic fermentation by Saccharomyces cerevisiae under high pressure  

Microsoft Academic Search

We monitored alcoholic fermentation in Saccharomyces cerevisiae as a function of high hydrostatic pressure. Ethanol production from 0.15 M glucose was measured by Raman spectroscopy in\\u000a situ in a diamond-anvil cell. At 10 MPa, fermentation proceeds three times faster than at ambient pressure and the fermentation\\u000a yield is enhanced by 5% after 24 h. Above 20 MPa, the reaction kinetics slows down with increasing

A. Picard; I. Daniel; G. Montagnac; P. Oger

2007-01-01

242

Quantitative analysis of borophosphosilicate glass films on silicon using infrared external reflection--absorption spectroscopy  

Microsoft Academic Search

Borophosphosilicate glass (BPSG) dielectric thin films deposited on both bare and oxide-coated undoped silicon wafers have been analyzed using infrared external reflection--absorption spectroscopy (IRRAS). The partial least-squares (PLS1) algorithm was used to simultaneously determine boron content, phosphorous content, and film thickness, with standard errors of prediction of 0.08 wt %, 0.11 wt %, and 24 A, respectively, in the BPSG

James E. Franke; L. Zhang; T. M. Niemczyk; D. M. Haaland; K. J. Radigan

1995-01-01

243

Saturated polarization spectroscopy with a picosecond laser for quantitative concentration measurements  

SciTech Connect

The collisional dependence of saturated polarization spectroscopy with a picosecond laser is investigated by probing hydroxyl in a flow cell. While nanosecond lasers have been used often for nonlinear diagnostic measurements of flame composition, picosecond lasers provide a potentially superior source for such techniques. Compared to a nanosecond laser, picosecond lasers produce significantly greater peak power for the same pulse energy, and this could improve the signal strength of multi-photon techniques such as degenerate four-wave mixing (DFWM) and polarization spectroscopy (PS). It has been suggested that the signal produced by such lasers would be less dependent on the collisional environment because the behavior of the molecular system probed by short-pulse lasers is governed more by the spectral width of the laser and the Doppler effect. To investigate the collisional dependence of the polarization spectroscopy signal generated with a picosecond laser, the authors probe the A{sup 2}{Sigma}{sup +}-X{sup 2}{Pi} (0,0) band of OH in a flow cell. In this well-controlled environment, the authors monitor the change in signal strength as they vary the buffer gas pressure by a factor of 50. Hydroxyl (OH) is created by photolysis of hydrogen peroxide using a Nd:YAG laser.

T. A. Reichardt; R. L. Farrow; F. D. Teodoro; R. P. Lucht

2000-02-11

244

Infrared spectroscopy reveals both qualitative and quantitative differences in equine subchondral bone during maturation  

NASA Astrophysics Data System (ADS)

The collagen phase in bone is known to undergo major changes during growth and maturation. The objective of this study is to clarify whether Fourier transform infrared (FTIR) microspectroscopy, coupled with cluster analysis, can detect quantitative and qualitative changes in the collagen matrix of subchondral bone in horses during maturation and growth. Equine subchondral bone samples (n = 29) from the proximal joint surface of the first phalanx are prepared from two sites subjected to different loading conditions. Three age groups are studied: newborn (0 days old), immature (5 to 11 months old), and adult (6 to 10 years old) horses. Spatial collagen content and collagen cross-link ratio are quantified from the spectra. Additionally, normalized second derivative spectra of samples are clustered using the k-means clustering algorithm. In quantitative analysis, collagen content in the subchondral bone increases rapidly between the newborn and immature horses. The collagen cross-link ratio increases significantly with age. In qualitative analysis, clustering is able to separate newborn and adult samples into two different groups. The immature samples display some nonhomogeneity. In conclusion, this is the first study showing that FTIR spectral imaging combined with clustering techniques can detect quantitative and qualitative changes in the collagen matrix of subchondral bone during growth and maturation.

Kobrina, Yevgeniya; Isaksson, Hanna; Sinisaari, Miikka; Rieppo, Lassi; Brama, Pieter A.; van Weeren, René; Helminen, Heikki J.; Jurvelin, Jukka S.; Saarakkala, Simo

2010-11-01

245

Spectral simulation methods for enhancing qualitative and quantitative analyses based on infrared spectroscopy and quantitative calibration methods for passive infrared remote sensing of volatile organic compounds  

NASA Astrophysics Data System (ADS)

Infrared spectroscopy (IR) has over the years found a myriad of applications including passive environmental remote sensing of toxic pollutants and the development of a blood glucose sensor. In this dissertation, capabilities of both these applications are further enhanced with data analysis strategies employing digital signal processing and novel simulation approaches. Both quantitative and qualitative determinations of volatile organic compounds are investigated in the passive IR remote sensing research described in this dissertation. In the quantitative work, partial least-squares (PLS) regression analysis is used to generate multivariate calibration models for passive Fourier transform IR remote sensing measurements of open-air generated vapors of ethanol in the presence methanol as an interfering species. A step-wise co-addition scheme coupled with a digital filtering approach is used to attenuate the effects of variation in optical path length or plume width. For the qualitative study, an IR imaging line scanner is used to acquire remote sensing data in both spatial and spectral domains. This technology is capable of not only identifying but also specifying the location of the sample under investigation. Successful implementation of this methodology is hampered by the huge costs incurred to conduct these experiments and the impracticality of acquiring large amounts of representative training data. To address this problem, a novel simulation approach is developed that generates training data based on synthetic analyte-active and measured analyte-inactive data. Subsequently, automated pattern classifiers are generated using piecewise linear discriminant analysis to predict the presence of the analyte signature in measured imaging data acquired in remote sensing applications. Near infrared glucose determinations based on the region of 5000--4000 cm-1 is the focus of the research in the latter part of this dissertation. A six-component aqueous matrix of glucose in the presence of five other interferent species, all spanning physiological levels, is analyzed quantitatively. Multivariate PLS regression analysis in conjunction with samples designated into a calibration set is used to formulate models for predicting glucose concentrations. Variations in the instrumental response caused by drift and environmental factors are observed to degrade the performance of these models. As a remedy, a model updating approach based on spectral simulation is developed that is highly successful in eliminating the adverse effects of non-chemical variations.

Sulub, Yusuf Ismail

246

Quantitative evaluation of pigment particles in organic layers by fibre-optics diffuse-reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

Fibre-optics diffuse-reflectance spectroscopy was used to evaluate pigment quantity in art glazes. Measurements are non-invasive, without any contact, and can be performed in situ, without moving the work of art under investigation from its conservation place. Reflectance spectra are processed using Kubelka Munk theory in order to obtain scattering and absorption parameters of the samples. Assuming a linear dependance of these optical properties with the pigment volume concentration of the paint layers, we were able to evaluate pigment quantities in the samples from reflectance measurements. Results are in excellent agreement with those obtained by X-ray diffraction and micro-X-ray fluorescence.

Dupuis, G.; Menu, M.

2005-02-01

247

Multivariate calibration applied to near-infrared spectroscopy for the quantitative analysis of dilute aqueous solutions  

NASA Astrophysics Data System (ADS)

The penetration depths possible with near-infrared spectroscopy make it well suited for reagentless monitoring of analytes in body fluids or noninvasive monitoring of human tissue. As an initial step in achieving these goals, we have conducted near-infrared in-vitro experiments of dilute aqueous solutions containing analytes of physiological importance. By combining partial least squares (PLS) multivariate calibration methods with Latin Hypercube statistical designs, we have obtained precise near-infrared spectral determinations of urea, creatinine, and NaCl in dilute aqueous solutions. Cross-validated PLS calibrations for the three analytes and temperature were very precise and resulted in R2 values greater than 0.997.

Haaland, David M.; Jones, Howland D.

1994-01-01

248

Domain Dynamics in Piezoresponse Force Spectroscopy: Quantitative Deconvolution and Hysteresis Loop Fine Structure  

SciTech Connect

Domain dynamics in the Piezoresponse Force Spectroscopy (PFS) experiment is studied using the combination of local hysteresis loop acquisition with simultaneous domain imaging. The analytical theory for PFS signal from domain of arbitrary cross-section and length is developed for the analysis of experimental data on Pb(Zr,Ti)O3 polycrystalline films. The results suggest formation of oblate domain at early stage of the nucleation and growth, consistent with efficient screening of depolarization field. The fine structure of the hysteresis loop is shown to be related to the observed jumps in the domain geometry during domain wall propagation (nanoscale Barkhausen jumps), indicative of strong domain-defect interactions.

Bdikin, Igor [University of Aveiro, Portugal; Kholkin, Andrei [University of Aveiro, Portugal; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Svechnikov, S. V. [National Academy of Science of Ukraine, Kiev, Ukraine; Kim, S.-H. [INOSTEK Inc., Gyeonggi, Korea; Kalinin, Sergei V [ORNL

2008-01-01

249

Quantitative comparison of the hemodynamic activation elicited by cardinal and oblique gratings with functional near-infrared spectroscopy.  

PubMed

Evidence has been accumulated for over a century indicating that the visual system of humans and many animals is more sensitive to contour stimulation at vertical or horizontal orientations than oblique orientations. However, the neural basis for this orientation anisotropy is still a subject of debate. In the present study, we recorded brain activity over the parietal-occipital and frontal lobes with functional near-infrared spectroscopy (fNIRS) when human participants were presented with gratings in different orientations. The oblique gratings induced a much larger change in the oxygenated hemoglobin concentration than vertical and horizontal gratings in the left occipital lobe. However, we did not find any significant orientation anisotropy in the frontal lobe. Our study showed that different quantitative changes in the hemoglobin concentrations occurred in response to differently oriented stimuli in the visual cortex and that fNIRS could potentially be a valuable tool in the assessment of the hemodynamic responses of the visual system. PMID:23528283

Sun, Meirong; Huang, Jing; Wang, Fang; An, An; Tian, Fenghua; Liu, Hanli; Niu, Haijing; Song, Yan

2013-05-01

250

Quantitative determination of the cubic-to-monoclinic phase transformation in fully stabilized zirconias by Raman spectroscopy  

SciTech Connect

Vibrational Raman spectroscopy was used successfully for the quantitative determination of the cubic and monoclinic phases of zirconia. Pressed pellets with known composition were prepared using monoclinic and cubic powders from different manufacturers and were used as standard mixtures. An intensity ratio plot of the 617-cm[sup [minus]1] band, which is attributed to the presence of both phases, to either the 177-cm[sup [minus]1] or 476-cm[sup [minus]1] monoclinic band against the inverse monoclinic molar fraction ([chi]) yielded a straight line which was described by ratio = 0.11[chi][sup [minus]1] + 0.26 and ratio = 0.12 [chi][sup [minus]1] + 0.29, respectively. The method was found to be independent of the origin of the powders.

Kontoyannis, C.G.; Carountzos, G. (Univ. of Patras (Greece))

1994-08-01

251

Quantitative detection of nitrate in water and wastewater by surface-enhanced Raman spectroscopy.  

PubMed

The presence of inorganic nitrogen species in water can be unsuitable for drinking and detrimental to the environment. In this study, a surface-enhanced Raman spectroscopy (SERS) method coupled with a commercially available gold nanosubstrate (a gold-coated silicon material) was evaluated for the detection of nitrate and nitrite in water and wastewater. Applications of SERS coupled with gold nanosubstrates resulted in an enhancement of Raman signals by a factor of ?10(4) compared to that from Raman spectroscopy. The new method was able to detect nitrate with linear ranges of 1-10,000 mg NO3(-)/L (R(2)=?0.978) and 1-100 mg NO3(-)/L (R(2)=?0.919) for water and wastewater samples, respectively. Among the common anions, phosphate appeared to be the major interfering anion affecting nitrate measurement. Nevertheless, the percentage error of nitrate measurement in wastewater by the proposed SERS method was comparable to that by ion chromatography. The nitrate detection limits in water and wastewater samples were about 0.5 mg/L. The SERS method could simultaneously detect sulfate, which may serve as a reference standard in water. These results suggested that the SERS coupled with nanosubstrates is a promising method to determine nitrate concentrations in water and wastewater. PMID:23108715

Gajaraj, Shashikanth; Fan, Cui; Lin, Mengshi; Hu, Zhiqiang

2012-10-30

252

Quantitative mapping of alluvial fan evolution using ground-based reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

The ability of field-based reflectance spectroscopy to resolve the relative proportions of Fe-oxides and clays in soils was used to map the composition, relative age and distribution of segments within late Quaternary fan systems in Sfakia, southwest Crete. The spectrometric results demonstrate that luvisols that have formed on the surfaces of fan segments are characterized by distinctive Fe-oxides (types) and clay minerals (species). Furthermore, Fe-oxide and clay concentrations display a clear and consistent trend whereby for each study fan luvisols formed on increasingly proximal fan segments are characterized by a progressive build-up of spectrally distinct secondary iron oxides and clay minerals, which suggests that proximal segments formed first. The relative ages and hence order of formation of segments suggested by the spectral data are strongly supported by an optically stimulated luminescence (OSL)-based geochronology which provides a tentative maximum age of 144 ka for the oldest (stage 1) surface and 11.2 ka for the youngest (stage 2C) surface. Moreover, the chronometric data indicate that time intervals of the order 20 to 25,000 years are necessary to generate sufficient differences in pedogenic Fe-oxides and clay concentrations to enable differentiation of fan segments by field spectroscopy.

Ferrier, Graham; Pope, Richard J. J.

2012-11-01

253

In vitro quantitation of human femoral artery atherosclerosis using near-infrared Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Near-infrared Raman spectroscopy has been used in vitro to identify calcified atherosclerotic plaques in human femoral arteries. Raman techniques allow for the identification of these plaques in a nondestructive manner, which may allow for the diagnosis of coronary artery disease in cardiac patients in the future. As Raman spectroscopy also reveals chemical information about the composition of the arteries, it can also be used as a prognostic tool. The in vivo detection of atherosclerotic plaques at risk for rupture in cardiac patients will enhance treatment methods while improving clinical outcomes for these procedures. Raman spectra were excited by an Invictus 785-nm NIR laser and measured with a fiber-coupled micro-Raman RXN system (Kaiser Optical Systems, Inc., Ann Arbor, MI) equipped with a 785 nm CW laser and CCD detector. Chemical mapping of arteries obtained post mortem allowed for the discrete location of atherosclerotic plaques. Raman peaks at 961 and 1073 cm-1 reveal the presence of calcium hydroxyapatite and carbonate apatite, which are known to be present in calcified plaques. By mapping the locations of these peaks the boundaries of the plaques can be precisely determined. Areas of varying degrees of calcification were also identified. Because this can be useful in determining the degree of plaque calcification and vessel stenosis, this may have a significant impact on the clinical treatment of atherosclerotic plaques in the future.

Dykes, Ava C.; Anastasiadis, Pavlos; Allen, John S., III; Sharma, Shiv K.

2012-05-01

254

In situ monitoring by quantitative Raman spectroscopy of alcoholic fermentation by Saccharomyces cerevisiae under high pressure.  

PubMed

We monitored alcoholic fermentation in Saccharomyces cerevisiae as a function of high hydrostatic pressure. Ethanol production from 0.15 M glucose was measured by Raman spectroscopy in situ in a diamond-anvil cell. At 10 MPa, fermentation proceeds three times faster than at ambient pressure and the fermentation yield is enhanced by 5% after 24 h. Above 20 MPa, the reaction kinetics slows down with increasing pressure. The pressure above which no more ethanol is produced is 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 up to 10 MPa. At higher pressures, they become progressively repressed, and they are completely inhibited above 87 MPa. Although fermentation was predicted to stop at ca. 50 MPa, due to the loss of activity of phosphofructokinase, the present study demonstrates that there is still an activity of ca. 30% of that measured at ambient pressure at 65 MPa. This study also validates the use of Raman spectroscopy for monitoring the metabolism of living microorganisms. PMID:17186315

Picard, A; Daniel, I; Montagnac, G; Oger, P

2006-12-22

255

Methane detection using Wavelength Modulation Spectroscopy and a multiline quantitation method  

NASA Astrophysics Data System (ADS)

In this paper the application of the Inverse Least Squares algorithm (ILS) to the detection of methane using its behaviour in the near-infrared band is presented. In order to test the effectiveness of this method, different methane concentrations were measured. Wavelength Modulation Spectroscopy (WMS) was employed to obtain the first and second harmonics of the modulation signal. The use of both harmonics in spectroscopy eliminates the dependence of the measured absorbance on parameters such as: fiber misalignments, optical power fluctuations, etc. This property greatly increases the accuracy of the concentration readings. The benefits of analysing multiple lines in gas detection are discussed together with the capabilities of the ILS algorithm. The ILS algorithm is based on the Beer-Lambert law. This law is extended to include multiple wavelengths and rearranged in such a way that the concentration of the chemical species depends on the measured absorbances. In order to apply the previous algorithm, three absorption lines centered at 1665.961 nm, 1666.201 nm and 1666.483 nm were used. The obtained results are compared with the most usual single-line calibration method based on linear regression. This comparison shows that ILS gives a superior performance. Specifically, results indicate that the ILS multiline algorithm is less noise dependent and has a higher reliability than single-line calibration methods.

Cubillas, Ana M.; Conde, Olga M.; Quintela, María Ángeles; Cobo, Adolfo; López-Higuera, José Miguel

2005-09-01

256

The assessment of chromophores in bleached cellulosic pulps employing UV-Raman spectroscopy.  

PubMed

UV-Resonance Raman (UV-RR) coupled with UV-visible Diffuse Reflectance (UV-vis DR) spectroscopy was applied to a solid-state study of chromophores in Eucalyptus globulus kraft cellulosic pulps bleached by chlorine dioxide and hydrogen peroxide. The UV-RR spectra were acquired at 325nm laser beam excitation, which was shown to be appropriate for selective analysis of chromophore structures in polysaccharides. The proposed approach allowed the monitoring of chromophores in pulps and to track the extent of polysaccharide oxidation. However, precaution was suggested while performing a quantitative analysis of chromophores at the characteristic band of approximately 1600cm(-1) because of charge transfer complexes (CTCs) that exist in the pulp. These CTCs can affect the intensity of the aforementioned band by diminishing the conjugate state in the chromophore moieties. The amount of carbonyl and carboxyl groups in polysaccharides correlated with the intensity of the band at 1093cm(-1). The analysis of UV-RR spectra revealed xylan as an important source of chromophores in eucalypt kraft pulp. PMID:20334853

Loureiro, Pedro E G; Fernandes, António J S; Carvalho, M Graça V S; Evtuguin, Dmitry V

2010-02-23

257

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.

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

2012-01-01

258

Quantitative analysis of chromate (CrVI) by normal Raman spectroscopy and surface-enhanced Raman spectroscopy using poly(diallyldimethylammonium) chloride-capped gold nanoparticles  

NASA Astrophysics Data System (ADS)

Chromate (CrVI) has emerged as a widespread environmental contaminant found in groundwater and surface water, and there is a great need for rapid detection and monitoring of this contaminant. Normal Raman scattering (NRS) spectroscopy with a detection limit of CrVI at concentrations of 0.2 g/L was attached. And surface-enhanced Raman scattering (SERS) spectroscopy technique was found to be capable of detecting CrVI at concentrations as low as 2.5 mg/L using poly(diallyldimethylammonium) chloride modified gold nanoparticles (PDDA-AuNPs) as a substrate. The SERS substrate was successfully fabricated by combining the selfassembly technique with a heat-treatment-based strategy using poly(diallyldimethylammonium) chloride (PDDA) as the reducing and stabilizing agents. With the 520 cm-1 band of silicon as internal standard, band intensity ratios of CrVI to silicon, that is I 902/ I 520, were found to have a quantitative relationship with a large concentration range of CrVI from 0.2 to 20.0 g/L for NRS ( R 2 = 0.994) and from 2.5 to 25.0 mg/L for SERS ( R 2 = 0.980), respectively. Besides, the SERS methodology was reproducible, and susceptible to the interference of pH value. The optimum pH for CrVI detection by SERS was 3.38. The application of NRS and SERS showed high practical potential for rapid screening and routine analysis of CrVI in environmental samples.

Xiao, J.; Meng, Y. Y.; Zhang, P. L.; Wen, W.; Liu, Z. M.; Zhang, T.

2012-10-01

259

Quantitative optical spectroscopy can identify long-term local tumor control in irradiated murine head and neck xenografts  

NASA Astrophysics Data System (ADS)

Noninvasive and longitudinal monitoring of tumor oxygenation status using quantitative diffuse reflectance spectroscopy is used to test whether a final treatment outcome could be estimated from early optical signatures in a murine model of head and neck cancer when treated with radiation. Implanted tumors in the flank of 23 nude mice are exposed to 39 Gy of radiation, while 11 animals exposed to sham irradiation serve as controls. Diffuse optical reflectance is measured from the tumors at baseline (prior to irradiation) and then serially until 17 days posttreatment. The fastest and greatest increase in baseline-corrected blood oxygen saturation levels are observed from the animals that show complete tumor regression with no recurrence 90 days postirradiation, relative to both untreated and treated animals with local recurrences. These increases in saturation are observed starting 5 days posttreatment and last up to 17 days posttreatment. This preclinical study demonstrates that diffuse reflectance spectroscopy could provide a practical method far more effective than the growth delay assay to prognosticate treatment outcome in solid tumors and may hold significant translational promise.

Vishwanath, Karthik; Klein, Daniel; Chang, Kevin; Schroeder, Thies; Dewhirst, Mark W.; Ramanujam, Nimmi

2009-09-01

260

Quantitative analysis of corroded copper patina by step scan and rapid scan photoacoustic Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Atmospheric corrosion enhanced by increasing air pollution causes increasing damage at valuable metallic monuments worthy of protection, e.g., the roof of the Stockholm City Hall. To explore the potential use of Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) in quantitative corrosion product analysis, the determination of the chemical composition of copper patina samples formed under atmospheric conditions was studied. As an experimental technique, we used a FTIR spectrometer in combination with sample-gas-microphone PAS using helium as the transfer gas at room temperature. The main components of the different samples-brochantite Cu4SO4(OH)6 and antlerite Cu3SO4(OH)4-were identified by their characteristic vibrational absorption bands. A quantitative analysis of these two components has been performed with rapid- and step-scan FTIR/PAS by using artificially corroded copper samples with differing ratios of composition. From these data, calibration curves were obtained allowing a nondestructive determination of the brochantite/antlerite ratio for quality control within an accuracy of about 10%.

Faubel, Werner; Heissler, Stefan; Palmer, Richard A.

2003-01-01

261

Compartment syndrome: A quantitative study of high-energy phosphorus compounds using sup 31 P-magnetic resonance spectroscopy  

SciTech Connect

The purpose of this study was to quantitate the intracellular high-energy phosphate compounds during 6 hours of tissue ischemia in the anterior tibial compartment of beagles subjected to an induced traumatized compartment syndrome. The goal of this work was to provide clinicians with objective criteria to augment clinical judgment regarding surgical intervention in the impending compartment syndrome. A beagle model was utilized in which the Delta pressure (difference between the mean arterial pressure and compartment pressure) could be controlled. The model, in conjunction with {sup 31}P-magnetic resonance spectroscopy (MRS), allowed a measure of high-energy phosphate compounds and pH in the compartment at various Delta pressures. The extent of ischemic metabolic insult in the compartment was then quantitated. Our data suggest the following: (1) lower Delta pressures result in a proportionally greater drop in the intracellular phosphocreatine ratio and pH; (2) at lower Delta pressures, there is proportionally greater decline in the percentage recovery post-fasciotomy; (3) blood pressure is extremely important and periods of hypotension may result in increased muscle damage at lower compartment pressures.

Heppenstall, R.B.; Sapega, A.A.; Izant, T.; Fallon, R.; Shenton, D.; Park, Y.S.; Chance, B. (Veterans Administration Medical Center, Philadelphia, PA (USA))

1989-08-01

262

Quantitative infrared spectroscopy of formalin-fixed, paraffin-embedded tissue specimens: paraffin wax removal with organic solvents.  

PubMed

Formalin-fixed, paraffin-embedded tissue specimens form the basis for diagnostic histopathology. Although adequate for morphologic visualization, clinical variability in preparation of formalin-fixed, paraffin-embedded clinical specimens represents an obstacle to quantitative molecular genetic analysis in areas such as genomics and proteomics. A quantitative reexamination of classical histopathology tissue preparation methods was initiated to determine which protocol steps might improve molecular analysis, beginning with deparaffinization. Infrared spectroscopy in the spectral region above 2000/cm of fixed sectioned model cell cultures through glass microscope slides showed all solvents remove over 97% of paraffin. To further compare extractions among solvents xylene, hexane and limonene, the correlation coefficients between the spectrum of paraffin and the spectra of the mounted extracted model tissue sections across the spectral interval containing the prominent CH stretching bands of paraffin were calculated. The correlation coefficients allow different extraction methods to be ranked in terms of how much paraffin remains. The results indicate that among 3 model tissue sample types, xylene extraction removes more paraffin than hexane or limonene. More importantly, these results establish a starting point from which further analysis of preanalytical processing methods can proceed. PMID:19786865

Meuse, Curtis W; Barker, Peter E

2009-12-01

263

Influence of particle size on the quantitative determination of salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy.  

PubMed

A second order polynomial calibration model was developed and statistically validated for the direct and non-destructive quantitative analysis - without sample preparation - of the active pharmaceutical ingredient (API) salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy. The calibration curve was modeled by plotting the peak intensity of the vector normalized spectral band between 757 and 784cm(-1) against the known salicylic acid concentrations in standards. At this band, no spectral interferences from the ointment vehiculum (white vaseline) are observed. For the validation of the polynomial model, its fit and its predictive properties were evaluated. The validated model was used for the quantification of 25 ointments, compounded by different retail pharmacists. The same standards and samples were used, both for development and validation of a regression model and for quantitative determination by HPLC - with sample preparation - as described for the related substances of salicylic acid in the Ph. Eur. IV. The quantification results obtained by the FT-Raman method corresponded with the HPLC results (p=0.22), provided that the particle size of salicylic acid in the standards is the same as in the analyzed samples. The non-destructive FT-Raman method is a reliable alternative for the destructive HPLC method, as it is faster and does not require sample pre-treatment procedures. PMID:17161940

De Beer, T R M; Baeyens, W R G; Heyden, Y Vander; Remon, J P; Vervaet, C; Verpoort, F

2006-11-18

264

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

265

Final Report: Investigation of Saturated Degenerate Four-Wave Mixing Spectroscopy For Quantitative Concentration Measurements  

SciTech Connect

Our research efforts over the last few years have focused on the development of strategies for the quantitative application of DFWM and PS in flame environments. We have developed, validated, and applied a theoretical methodology based on direct numerical integration (DNI) of the time-dependent density matrix equations for analysis of the physics of the DFWM and PS processes. The incorporation of the Zeeman state structure of the energy levels of the radiative transitions has allowed us to investigate the physics of the PS process and polarization effects in DFWM. Our research effort has focused mainly on the moderate saturation regime, with laser pulse lengths significantly greater than characteristic collisional times, and with the assumption of monochromatic lasers. Recently, we have completed a study of multi-axial-mode laser effects of homogeneously broadened PS.

Lucht, R. P.

2001-03-20

266

Purity analysis of hydrogen cyanide, cyanogen chloride and phosgene by quantitative (13)C NMR spectroscopy.  

PubMed

Hydrogen cyanide, cyanogen chloride and phosgene are produced in tremendously large quantities today by the chemical industry. The compounds are also particularly attractive to foreign states and terrorists seeking an inexpensive mass-destruction capability. Along with contemporary warfare agents, therefore, the US Army evaluates protective equipment used by warfighters and domestic emergency responders against the compounds, and requires their certification at > or = 95 carbon atom % before use. We have investigated the (13)C spin-lattice relaxation behavior of the compounds to develop a quantitative NMR method for characterizing chemical lots supplied to the Army. Behavior was assessed at 75 and 126 MHz for temperatures between 5 and 15 degrees C to hold the compounds in their liquid states, dramatically improving detection sensitivity. T(1) values for cyanogen chloride and phosgene were somewhat comparable, ranging between 20 and 31 s. Hydrogen cyanide values were significantly shorter at 10-18 s, most likely because of a (1)H--(13)C dipolar contribution to relaxation not possible for the other compounds. The T(1) measurements were used to derive relaxation delays for collecting the quantitative (13)C data sets. At 126 MHz, only a single data acquisition with a cryogenic probehead gave a signal-to-noise ratio exceeding that necessary for certifying the compounds at > or = 95 carbon atom % and 99% confidence. Data acquired at 75 MHz with a conventional probehead, however, required > or = 5 acquisitions to reach this certifying signal-to-noise ratio for phosgene, and >/= 12 acquisitions were required for the other compounds under these same conditions. In terms of accuracy and execution time, the NMR method rivals typical chromatographic methods. PMID:17924355

Henderson, Terry J; Cullinan, David B

2007-11-01

267

Quantitative compositional analysis using thermal emission spectroscopy: Application to igneous and metamorphic rocks  

NASA Astrophysics Data System (ADS)

The mineral composition of a suite of igneous and metamorphic rocks was determined using the thermal infrared emission spectra of these rocks in a linear spectral deconvolution algorithm. This algorithm assumes that the infrared spectrum of each rock is a linear mixture of the component mineral spectra weighted by volume abundance. A diverse suite of 36 common rock-forming and accessory minerals was used in the deconvolution. The model was tested by comparing the mineralogy derived from the infrared spectrum with petrographically estimated abundances for 45 igneous and 51 metamorphic rock samples. The mineral abundances derived from these two techniques agree to within +/-7-15% for the primary minerals feldspar, pyroxene, quartz, and calcite/dolomite and +/-9-17% for secondary minerals such as micas and amphiboles. These differences are comparable to the error for traditional thin section mode estimates, which are +/-5-15% for major minerals and <=5% for minor minerals. The detection limit for the primary and secondary minerals found in the rocks analyzed ranged from 5 to 10%. Each major rock type studied here was easily distinguished by its spectral characteristics. The best results, in both the qualitative determination of the rock type and dominant minerals and the quantitative reproduction of absorption features and mineral composition, were obtained for igneous rock samples. For metamorphic rocks, pelite and quartzo-feldspathic samples gave slightly better results than calcareous or mafic samples. A controlled analysis, in which the end-member suite was reduced based on an initial estimate of the rock type, only improved the results by several percent for most primary and secondary minerals. The quality of the obtained results demonstrates that a linear deconvolution of infrared emission spectra provides an accurate, rapid technique for determining the quantitative mineral composition of rock samples in a laboratory and has application to future in situ measurements.

Feely, Kimberly C.; Christensen, Philip R.

1999-10-01

268

Spectroscopy  

NSDL National Science Digital Library

This page is a set of concept test questions about organic chemistry spectroscopy. There are ten questions about topics including trans isomer and NMR spectra, C-X vibration, wavenumber absorption, and carbon signals.

2008-03-11

269

Microfluidic impedance spectroscopy as a tool for quantitative biology and biotechnology  

PubMed Central

A microfluidic device that is able to perform dielectric spectroscopy is developed. The device consists of a measurement chamber that is 250??m thick and 750??m in radius. Around 1000 cells fit inside the chamber assuming average quantities for cell radius and volume fraction. This number is about 1000 folds lower than the capacity of conventional fixtures. A T-cell leukemia cell line Jurkat is tested using the microfluidic device. Measurements of deionized water and salt solutions are utilized to determine parasitic effects and geometric capacitance of the device. Physical models, including Maxwell-Wagner mixture and double shell models, are used to derive quantities for sub-cellular units. Clausius-Mossotti factor of Jurkat cells is extracted from the impedance spectrum. Effects of cellular heterogeneity are discussed and parameterized. Jurkat cells are also tested with a time domain reflectometry system for verification of the microfluidic device. Results indicate good agreement of values obtained with both techniques. The device can be used as a unique cell diagnostic tool to yield information on sub-cellular units.

Sabuncu, Ahmet C.; Zhuang, Jie; Kolb, Juergen F.; Beskok, Ali

2012-01-01

270

A slit grating spectrograph for quantitative soft x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

In this article we describe a new slit grating spectrograph which is based on an e-beam written 10 000 linepairs/mm freestanding transmission diffraction grating. In combination with a thinned, back-illuminated charge coupled device (CCD), the spectrograph allows for real-time spectroscopy of laser-produced plasma x-ray sources within the wavelength region ?=1-20 nm. Calibration of grating and CCD allow for the possibility to measure absolute photon fluxes, currently within the wavelength region ?=1-6 nm. The compact spectrograph is easy to align and flexible in its use. Absolutely calibrated spectra were obtained from a liquid-jet laser-plasma source in the water window, with a spectral resolution ?/??>=330 at ?=3.37 nm. A simple change in experimental geometry allowed single-shot spectra to be recorded with ?/??>=60 at the same wavelength. In addition, spectra from this laser-plasma source were measured within the range ?=9-20 nm.

Wilhein, T.; Rehbein, S.; Hambach, D.; Berglund, M.; Rymell, L.; Hertz, H. M.

1999-03-01

271

On quantitative measurements in phase-shift off-axis cavity-enhanced absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The contribution of amplified spontaneous emission (ASE) from a fibre-coupled DFB near-infrared diode laser has been analysed for phase-shift off-axis cavity-enhanced absorption spectroscopy (PS-OA-CEAS). A new phasor representation of the laser coherent component and the ASE components, with both long and short ring-down times, has been proposed for calculating absorption spectra from the phase and amplitude of the cavity output intensity. The line strength of the R(4) CO 2 line at 1604.7 nm has been estimated for the case when the intensity of the ASE component, passing through the cavity without long-term ringing, contributes up to ˜60% of the total light intensity observed at the cavity output. It has been shown that neglecting the ASE contribution can lead to an overestimation of the line strength by a factor of ˜4.8, whereas the line strength, calculated in accordance with the phasor model introduced here, is close to the actual line strength from Hitran.

Kasyutich, Vasili L.; Martin, Philip A.

2007-09-01

272

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  1x10(-6) to 5x10(-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. PMID:23973576

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

2013-08-03

273

Quantitative analysis of cotton (Gossypium hirsutum) lint trash by fluorescence spectroscopy.  

PubMed

The presence of cotton plant botanical components, or trash, embedded in lint subsequent to harvesting and ginning is an important criterion in the classification of baled cotton by the U.S. Department of Agriculture Agricultural Marketing Service. The trash particles may be reduced in size to the point that specific trash types are not identifiable by image or gravimetric analysis, and it is desirable to quantify different trash types so that processing lines may be optimized for removal of the most problematic trash to enhance processing performance and cotton lint quality. Currently, there are no methods available to adequately quantify cotton lint trash based on botanical origin. The present work attempts to address this issue through the analysis by fluorescence spectroscopy of dimethyl sulfoxide extracts of mixtures of six botanical trash types. The fluorescence data are subsequently subjected to chemometric analysis. The resulting 6 partial least-squares calibration models obtained from 128 mixtures are demonstrated in the case of leaf and hull to be capable of predicting individual trash component concentrations with a high degree of confidence. PMID:17536818

Gamble, Gary R; Foulk, Jonn A

2007-05-31

274

Identification and quantitation assays for intact tablets of two related pharmaceutical preparations by reflectance near-infrared spectroscopy: validation of the procedure  

Microsoft Academic Search

Quantitative analysis based on near-infrared (NIR) spectroscopy uses individual calibration equations for each sample studied because of the need to model all possible chemical and physical variability sources. A NIR method, using a fibre optical probe, for the analysis of two different and related pharmaceuticals from two different production steps (cores and tablets) is studied. Both pharmaceuticals have the same

M. Blanco; A. Eustaquio; J. M. González; D. Serrano

2000-01-01

275

Quantitative analysis of mephedrone using liquid chromatography tandem mass spectroscopy: application to human hair.  

PubMed

Recent abuse of designer drugs such as mephedrone has presented a requirement for sensitive, reliable and reproducible methods for the detection of these controlled drugs in different matrices. This study focuses on a fully developed validated method for the quantitative analysis of mephedrone and its two metabolites 4-methylephedrine and 4-methylnorephedrine in human hair. The calibration curve was found to be linear in the range 5-100 pg/mg for mephedrone and 10-150 pg/mg for 4-methylephedrine and 4-methylnorephedrine. The method was successfully validated for the intraday precision, interday precision, limit of detection, accuracy and extraction recovery. Five out of 154 hair samples were confirmed to be positive for mephedrone. Due to the structural similarities to other methcathinones and amphetamines, one can propose the metabolism for mephedrone based on a similar pathway that has been previously used for these psychoactive drugs. The outlined method can be valuable for the future detection of mephedrone and its two metabolites in hair. PMID:22209483

Shah, Syeda A B; Deshmukh, Nawed I K; Barker, James; Petróczi, Andrea; Cross, Paul; Archer, Roland; Naughton, Declan P

2011-12-03

276

Fiber optic based multiparametric spectroscopy in vivo: toward a new quantitative tissue vitality index  

NASA Astrophysics Data System (ADS)

In our previous publication (Mayevsky et al SPIE 5326: 98-105, 2004) we described a multiparametric fiber optic system enabling the evaluation of 4 physiological parameters as indicators of tissue vitality. Since the correlation between the various parameters may differ in various pathophysiological conditions there is a need for an objective quantitative index that will integrate the relative changes measured in real time by the multiparametric monitoring system into a single number-vitality index. Such an approach to calculate tissue vitality index is critical for the possibility to use such an instrument in clinical environments. In the current presentation we are reporting our preliminary results indicating that calculation of an objective tissue vitality index is feasible. We used an intuitive empirical approach based on the comparison between the calculated index by the computer and the subjective evaluation made by an expert in the field of physiological monitoring. We used the in vivo brain of rats as an animal model in our current studies. The rats were exposed to anoxia, ischemia and cortical spreading depression and the responses were recorded in real time. At the end of the monitoring session the results were analyzed and the tissue vitality index was calculated offline. Mitochondrial NADH, tissue blood flow and oxy-hemoglobin were used to calculate the vitality index of the brain in vivo, where each parameter received a different weight, in each experiment type based on their significance. It was found that the mitochondrial NADH response was the main factor affected the calculated vitality index.

Kutai-Asis, Hofit; Barbiro-Michaely, Efrat; Deutsch, Assaf; Mayevsky, Avraham

2006-03-01

277

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

278

Quantitative determination of prednisone in tablets by infrared attenuated total reflection and Raman spectroscopy.  

PubMed

The quantification of prednisone in tablets was performed using partial least squares (PLS) models based on FTIR-attenuated total reflection (ATR) and FT-Raman spectra. To compare the predictive ability of these models, the relative standard error of prediction (RSEP) values were calculated. In the case of prednisone determination from the FT-Raman data, RSEP values of 3.1 and 3.2% for the calibration and validation data sets were obtained. For FTIR-ATR models, which were constructed using five spectra for each sample, these errors amounted to 2.6 and 2.9%, respectively. Four commercial products containing 1, 5, 10, and 20 mg prednisone/tablet were quantified. Concentrations derived from the elaborated models correlated strongly with the results of reference analyses and with the declared values (in parentheses). The analyses gave recoveries of 100.0-101.6% (100.1-103.0%) and 98.1-103.2% (100.4-102.9%) for FTIR-ATR and FT-Raman data, respectively. A successful quantification of prednisolone in tablets containing 5 mg active ingredient/tablet was also performed using the PLS model, which was based on FTIR-ATR spectra, with a recovery of 99.8 (98.8%). Both reported spectroscopic techniques can be used as fast and convenient alternatives to the standard pharmacopeial methods of prednisone and prednisolone quantification in solid dosage forms. However, in the case of FTIR-ATR spectroscopy, it is necessary to repeat measurements several times to obtain sufficiently low quantification errors. PMID:22816265

Mazurek, Sylwester; Szostak, Roman

279

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

PubMed

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

2012-08-06

280

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.

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

2012-01-01

281

Quantitative analysis of borophosphosilicate glass films on silicon using infrared external reflection--absorption spectroscopy  

SciTech Connect

Borophosphosilicate glass (BPSG) dielectric thin films deposited on both bare and oxide-coated undoped silicon wafers have been analyzed using infrared external reflection--absorption spectroscopy (IRRAS). The partial least-squares (PLS1) algorithm was used to simultaneously determine boron content, phosphorous content, and film thickness, with standard errors of prediction of 0.08 wt %, 0.11 wt %, and 24 A, respectively, in the BPSG films on oxide-coated wafers (similar results were obtained with the bare wafer BPSG sample set). These results were statistically equivalent to the precisions of the reference methods used to determine each BPSG property, indicating that the precisions of the PLS1 models were limited by the precisions of the reference methods. IRRAS reproducibility and repeatability results verified that the method can be more precise than the reference methods. The reproducibility results were derived from the standard deviation of ten PLS1 predictions of ten IRRAS spectra that were obtained from a single BPSG sample that was moved in and out of the sample chamber between each spectral measurement. The repeatability results were obtained similarly, but the sample was not moved between acquiring the ten spectra. The precision of the IRRAS method from the repeatability data was found to be {plus_minus}0.006 wt % B, {plus_minus}0.011 wt % P, and {plus_minus}4 A film thickness. The reproducibility results were generally less precise than the repeatability results. Studies done as a function of spectral resolution and signal averaging showed that very rapid IRRAS measurements could be made (up to 2 Hz) with high PLS1 prediction precision for the three calibrated BPSG properties. The results show that the IRRAS technique has great potential for rapid, at-line quality control monitoring of BPSG thin films on undoped silicon wafers. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

Franke, J.E.; Zhang, L.; Niemczyk, T.M. [Chemistry Department, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Haaland, D.M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0343 (United States); Radigan, K.J. [National Semiconductor Corporation, Santa Clara, California 95052 (United States)

1995-07-01

282

Quantitative Zn speciation in a contaminated dredged sediment by ?-PIXE, ?-SXRF, EXAFS spectroscopy and principal component analysis  

NASA Astrophysics Data System (ADS)

Dredging and disposal of sediments onto agricultural soils is a common practice in industrial and urban areas that can be hazardous to the environment when the sediments contain heavy metals. This chemical hazard can be assessed by evaluating the mobility and speciation of metals after sediment deposition. In this study, the speciation of Zn in the coarse (500 to 2000 ?m) and fine (<2 ?m) fractions of a contaminated sediment dredged from a ship canal in northern France and deposited on an agricultural soil was determined by physical analytical techniques on raw and chemically treated samples. Zn partitioning between coexisting mineral phases and its chemical associations were first determined by micro-particle-induced X-ray emission and micro-synchrotron-based X-ray radiation fluorescence. Zn-containing mineral species were then identified by X-ray diffraction and powder and polarized extended X-ray absorption fine structure spectroscopy (EXAFS). The number, nature, and proportion of Zn species were obtained by a coupled principal component analysis (PCA) and least squares fitting (LSF) procedure, applied herein for the first time to qualitatively (number and nature of species) and quantitatively (relative proportion of species) speciate a metal in a natural system. The coarse fraction consists of slag grains originating from nearby Zn smelters. In this fraction, Zn is primarily present as sphalerite (ZnS) and to a lesser extent as willemite (Zn 2SiO 4), Zn-containing ferric (oxyhydr)oxides, and zincite (ZnO). In the fine fraction, ZnS and Zn-containing Fe (oxyhydr)oxides are the major forms, and Zn-containing phyllosilicate is the minor species. Weathering of ZnS, Zn 2SiO 4, and ZnO under oxidizing conditions after the sediment disposal accounts for the uptake of Zn by Fe (oxyhydr)oxides and phyllosilicates. Two geochemical processes can explain the retention of Zn by secondary minerals: uptake on preexisting minerals and precipitation with dissolved Fe and Si. The second process likely occurs because dissolved Zn and Si are supersaturated with respect to Zn phyllosilicate. EXAFS spectroscopy, in combination with PCA and LSF, is shown to be a meaningful approach to quantitatively determining the speciation of trace elements in sediments and soils.

Isaure, Marie-Pierre; Laboudigue, Agnès; Manceau, Alain; Sarret, Géraldine; Tiffreau, Christophe; Trocellier, Patrick; Lamble, Géraldine; Hazemann, Jean-Louis; Chateigner, Daniel

2002-05-01

283

Brain metabolite composition during early human brain development as measured by quantitative in vivo 1H magnetic resonance spectroscopy.  

PubMed

Biochemical maturation of the brain can be studied noninvasively by (1)H magnetic resonance spectroscopy (MRS) in human infants. Detailed time courses of cerebral tissue contents are known for the most abundant metabolites only, and whether or not premature birth affects biochemical maturation of the brain is disputed. Hence, the last trimester of gestation was observed in infants born prematurely, and their cerebral metabolite contents at birth and at expected term were compared with those of fullterm infants. Successful quantitative short-TE (1)H MRS was performed in three cerebral locations in 21 infants in 28 sessions (gestational age 32-43 weeks). The spectra were analyzed with linear combination model fitting, considerably extending the range of observable metabolites to include acetate, alanine, aspartate, cholines, creatines, gamma-aminobutyrate, glucose, glutamine, glutamate, glutathione, glycine, lactate, myo-inositol, macromolecular contributions, N-acetylaspartate, N-acetylaspartylglutamate, o-phosphoethanolamine, scyllo-inositol, taurine, and threonine. Significant effects of age and location were found for many metabolites, including the previously observed neuronal maturation reflected by an increase in N-acetylaspartate. Absolute brain metabolite content in premature infants at term was not considerably different from that in fullterm infants, indicating that prematurity did not affect biochemical brain maturation substantially in the studied population, which did not include infants of extremely low birthweight. PMID:12465103

Kreis, R; Hofmann, L; Kuhlmann, B; Boesch, C; Bossi, E; Hüppi, P S

2002-12-01

284

Proton HR-MAS spectroscopy and quantitative pathologic analysis of MRI/3D-MRSI-targeted postsurgical prostate tissues.  

PubMed

Proton high-resolution magic angle spinning ((1)H HR-MAS) NMR spectroscopy and quantitative histopathology were performed on the same 54 MRI/3D-MRSI-targeted postsurgical prostate tissue samples. Presurgical MRI/3D-MRSI targeted healthy and malignant prostate tissues with an accuracy of 81%. Even in the presence of substantial tissue heterogeneity, distinct (1)H HR-MAS spectral patterns were observed for different benign tissue types and prostate cancer. Specifically, healthy glandular tissue was discriminated from prostate cancer based on significantly higher levels of citrate (P = 0.04) and polyamines (P = 0.01), and lower (P = 0.02) levels of the choline-containing compounds choline, phosphocholine (PC), and glycerophosphocholine (GPC). Predominantly stromal tissue lacked both citrate and polyamines, but demonstrated significantly (P = 0.01) lower levels of choline compounds than cancer. In addition, taurine, myo-inositol, and scyllo-inositol were all higher in prostate cancer vs. healthy glandular and stromal tissues. Among cancer samples, larger increases in choline, and decreases in citrate and polyamines (P = 0.05) were observed with more aggressive cancers, and a MIB-1 labeling index correlated (r = 0.62, P = 0.01) with elevated choline. The elucidation of spectral patterns associated with mixtures of different prostate tissue types and cancer grades, and the inclusion of new metabolic markers for prostate cancer may significantly improve the clinical interpretation of in vivo prostate MRSI data. PMID:14587005

Swanson, Mark G; Vigneron, Daniel B; Tabatabai, Z Laura; Males, Ryan G; Schmitt, Lars; Carroll, Peter R; James, Joyce K; Hurd, Ralph E; Kurhanewicz, John

2003-11-01

285

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

NASA Astrophysics Data System (ADS)

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

King, Galen B.; Laurendeau, Normand M.; Fiechtner, Gregory J.

1995-02-01

286

Noninvasive, quantitative analysis of drug mixtures in containers using spatially offset Raman spectroscopy (SORS) and multivariate statistical analysis.  

PubMed

In this paper, spatially offset Raman spectroscopy (SORS) is demonstrated for noninvasively investigating the composition of drug mixtures inside an opaque plastic container. The mixtures consisted of three components including a target drug (acetaminophen or phenylephrine hydrochloride) and two diluents (glucose and caffeine). The target drug concentrations ranged from 5% to 100%. After conducting SORS analysis to ascertain the Raman spectra of the concealed mixtures, principal component analysis (PCA) was performed on the SORS spectra to reveal trends within the data. Partial least squares (PLS) regression was used to construct models that predicted the concentration of each target drug, in the presence of the other two diluents. The PLS models were able to predict the concentration of acetaminophen in the validation samples with a root-mean-square error of prediction (RMSEP) of 3.8% and the concentration of phenylephrine hydrochloride with an RMSEP of 4.6%. This work demonstrates the potential of SORS, used in conjunction with multivariate statistical techniques, to perform noninvasive, quantitative analysis on mixtures inside opaque containers. This has applications for pharmaceutical analysis, such as monitoring the degradation of pharmaceutical products on the shelf, in forensic investigations of counterfeit drugs, and for the analysis of illicit drug mixtures which may contain multiple components. PMID:22524958

Olds, William J; Sundarajoo, Shankaran; Selby, Mark; Cletus, Biju; Fredericks, Peter M; Izake, Emad L

2012-05-01

287

Quantitative measurement of cerebral blood flow in a juvenile porcine model by depth-resolved near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Nearly half a million children and young adults are affected by traumatic brain injury each year in the United States. Although adequate cerebral blood flow (CBF) is essential to recovery, complications that disrupt blood flow to the brain and exacerbate neurological injury often go undetected because no adequate bedside measure of CBF exists. In this study we validate a depth-resolved, near-infrared spectroscopy (NIRS) technique that provides quantitative CBF measurement despite significant signal contamination from skull and scalp tissue. The respiration rates of eight anesthetized pigs (weight: 16.2+/-0.5 kg, age: 1 to 2 months old) are modulated to achieve a range of CBF levels. Concomitant CBF measurements are performed with NIRS and CT perfusion. A significant correlation between CBF measurements from the two techniques is demonstrated (r2=0.714, slope=0.92, p<0.001), and the bias between the two techniques is -2.83 mL.min-1.100 g-1 (CI0.95: -19.63 mL.min-1.100 g-1-13.9 mL.min-1.100 g-1). This study demonstrates that accurate measurements of CBF can be achieved with depth-resolved NIRS despite significant signal contamination from scalp and skull. The ability to measure CBF at the bedside provides a means of detecting, and thereby preventing, secondary ischemia during neurointensive care.

Elliott, Jonathan T.; Diop, Mamadou; Tichauer, Kenneth M.; Lee, Ting-Yim; Lawrence, Keith St.

2010-05-01

288

Quantitative study of protein-protein interactions in live cell by dual-color fluorescence correlation spectroscopy.  

PubMed

Dual-color FCS is a powerful method to monitor protein-protein interactions in living cells. The main idea is based on the cross-correlation analysis of temporal fluorescence intensity fluctuations of two fluorescent proteins to obtain their co-diffusion and relative concentration. But, when performing these experiments, the spectral overlap in the emission of the two colors produces an artifact that corrupts the cross-correlation data: spectral bleed-through. We have shown that problems with cross talk are overcome with Fluorescence Lifetime Correlation Spectroscopy (FLCS). FLCS applied to dual-color cross-correlation, utilizing for example eGFP and mCherry fluorescent proteins, allows the determination of protein-protein interactions in living cells without the need of spectral bleed-through calibration. Here, we present in detail how this methodology can be implemented using a commercial setup (Microtime from PicoQuant, SP8 SMD from Leica or any conventional confocal with PicoQuant TCSPC module, and also with a Becker and Hickl TCSPC module). The dual-color FLCS experimental procedure where the different laser intensities do not have to be controlled during the experiment constitutes a very powerful technique to quantitatively study protein interactions in live samples. PMID:24108650

Padilla-Parra, Sergi; Audugé, Nicolas; Coppey-Moisan, Maïté; Tramier, Marc

2014-01-01

289

A quantitative method to detect explosives and other selected semivolatiles in soil samples by Fourier transform infrared spectroscopy  

SciTech Connect

The current methods for hazardous waste site characterization are time consuming, cumbersome, and expensive. Typically, characterization requires a preliminary site assessment and subsequent sampling of potentially contaminated soils and waters. The samples are sent to laboratories for analysis using EPA-certified methods. It is often necessary to repeat the entire sampling-analysis cycle to characterize a site completely and accurately. For these reasons, new methods of site assessment and characterization are continually being researched. TWs paper describes a Fourier transform infrared (FTIR) spectroscopy method that rapidly screens soil samples from potentially hazardous waste sites. Analysis of a soil sample by FTIR takes approximately 10 minutes. The method has been developed to identify and quantify explosives in the field and is directly applicable to selected volatile organics, semivolatile organics, and pesticides. The soil samples are desorbed in a CDS 122 thermal desorption unit under vacuum into a variable pathlength, long-path cell heated to 180{degrees}C. The spectral data, 128 co-added scans at I cm{sup {minus}l} resolution, are collected and stored using a Nicolet 60SX FTIR spectrometer. Classical least squares (CLS) analysis has been used to obtain quantitative results.

Clapper-Gowdy, M.; Demirgian, J. (Argonne National Lab., IL (United States)); Lang, K.; Robaittaille, G. (Army Toxic and Hazardous Materials Agency, Aberdeen Proving Ground, MD (United States))

1992-01-01

290

A flash photolysis and stopped-flow spectroscopy study of 3',4'-dihydroxy-7-O-?-D-glucopyranosyloxyflavylium chloride, an anthocyanin analogue exhibiting efficient photochromic properties.  

PubMed

The complete determination of all rate and equilibrium constants of the network of reversible chemical reactions involving the anthocyanin analogue, 3',4'-dihydroxy-7-O-?-D-glucopyranosyloxyflavylium chloride, was achieved by means of UV-visible spectroscopy, flash photolysis and pH jumps monitored by stopped-flow. An energy level diagram containing all the data was obtained. A detailed step by step procedure illustrating all the calculations is reported. PMID:23280153

Petrov, Vesselin; Gavara, Raquel; Dangles, Olivier; Al Bittar, Sheiraz; Mora-Soumille, Nathalie; Pina, Fernando

2013-01-02

291

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.

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

2002-01-01

292

Use of FT-NIR transmission spectroscopy for the quantitative analysis of an active ingredient in a translucent pharmaceutical topical gel formulation  

Microsoft Academic Search

The objective of this study was to demonstrate the use of transmission Fourier transform near-infrared (FT-NIR) spectroscopy\\u000a for quantitative analysis of an active ingredient in a translucent gel formulation. Gels were prepared using Carbopol 980\\u000a with 0%, 1%, 2%, 4%, 6%, and 8% ketoprofen and analyzed with an FT-NIR spectrophotometer operated in the transmission mode.\\u000a The correlation coefficient of the

Mark S. Kemper; Edgar J. Magnuson; Stephen R. Lowry; William J. McCarthy; Napasinee Aksornkoae; D. Christopher Watts; James R. Johnson; Atul J. Shukla

2001-01-01

293

The influence of multivariate analysis methods and target grain size on the accuracy of remote quantitative chemical analysis of rocks using laser induced breakdown spectroscopy  

Microsoft Academic Search

Laser-induced breakdown spectroscopy (LIBS) was used to quantitatively analyze 195 rock slab samples with known bulk chemical compositions, 90 pressed-powder samples derived from a subset of those rocks, and 31 pressed-powder geostandards under conditions that simulate the ChemCam instrument on the Mars Science Laboratory Rover (MSL), Curiosity. The low-volatile (<2 wt.%) silicate samples (90 rock slabs, corresponding powders, and 22

Ryan B. Anderson; Richard V. Morris; Samuel M. Clegg; James F. Bell; Roger C. Wiens; Seth D. Humphries; Trevor G. Graff; Rhonda McInroy

2011-01-01

294

The influence of multivariate analysis methods and target grain size on the accuracy of remote quantitative chemical analysis of rocks using laser induced breakdown spectroscopy  

Microsoft Academic Search

Laser-induced breakdown spectroscopy (LIBS) was used to quantitatively analyze 195 rock slab samples with known bulk chemical compositions, 90 pressed-powder samples derived from a subset of those rocks, and 31 pressed-powder geostandards under conditions that simulate the ChemCam instrument on the Mars Science Laboratory Rover (MSL), Curiosity. The low-volatile (<2wt.%) silicate samples (90 rock slabs, corresponding powders, and 22 geostandards)

Ryan B. Anderson; Richard V. Morris; Samuel M. Clegg; James F. Bell; Roger C. Wiens; Seth D. Humphries; Trevor G. Graff; Rhonda McInroy

2011-01-01

295

Influence of Laser Wavelength on Laser-induced Breakdown Spectroscopy Applied to Semi-Quantitative Analysis of Trace-Elements in a Plant Sample  

Microsoft Academic Search

Laser-induced breakdown spectroscopy (LIBS) as a powerful analytical technique is applied to analyze trace-elements in fresh plant samples. We investigate the LIBS spectra of fresh holly leaves and observe more than 430 lines emitted from 25 elements and molecules in the region 230-438 nm. The influence of laser wavelength on LIBS applied to semi-quantitative analysis of trace-element contents in plant

Da-Cheng Zhang; Xin-Wen Ma; Wei-Qiang Wen; Peng-Ju Zhang; Xiao-Long Zhu; Bin Li; Hui-Ping Liu

2010-01-01

296

Quantitative determination of unsaturation in photocured halogenated acrylates and methacrylates by FT-IR and Raman-spectroscopy and by thermal analysis  

Microsoft Academic Search

The photo-polymerization of tetrachloroethylacrylate (TeCEA), pentafluorophenylacrylate (PFPA) and pentafluorophenylmethacrylate (PFPMA) was examined by quantitative FT-IR and FT-Raman spectroscopy and by thermal analysis. The agreement between the FT-Raman results and thermal analysis was good for all monomers. The FT-IR measurement yielded higher percentages of unsaturation than the two other techniques in the slowly reacting PFPMA polymer, which can be attributed to

M. Jöhnck; L. Müller; A. Neyer; J. W. Hofstraat

1999-01-01

297

Direct identification and quantitative determination of costunolide and dehydrocostuslactone in the fixed oil of Laurus novocanariensis by 13C-NMR spectroscopy.  

PubMed

The fixed oil of Laurus novocanariensis (previously L. azorica) contains mostly glycerides together with minor non-saponifiable compounds. The direct identification and quantitative determination of costunolide and dehydrocostuslactone, two sesquiterpene lactones components of the oil that exhibit biological activities, is described. The analysis was carried out using 13C-NMR spectroscopy (signal acquisition with inverse gated decoupling of protons; diglyme as internal standard) without separation, derivatisation or any sample preparation. PMID:15881118

Ferrari, Bernard; Castilho, Paula; Tomi, Félix; Rodrigues, Ana Isabel; do Ceu Costa, Maria; Casanova, Joseph

298

Influence of Laser Wavelength on Laser-induced Breakdown Spectroscopy Applied to Semi-Quantitative Analysis of Trace-Elements in a Plant Sample  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) as a powerful analytical technique is applied to analyze trace-elements in fresh plant samples. We investigate the LIBS spectra of fresh holly leaves and observe more than 430 lines emitted from 25 elements and molecules in the region 230-438 nm. The influence of laser wavelength on LIBS applied to semi-quantitative analysis of trace-element contents in plant samples is studied. The results show that the UV laser has lower relative standard deviations and better repeatability for semi-quantitative analysis of trace-element contents in plant samples. This work may be helpful for improving the quantitative analysis power of LIBS applied to plant samples.

Zhang, Da-Cheng; Ma, Xin-Wen; Wen, Wei-Qiang; Zhang, Peng-Ju; Zhu, Xiao-Long; Li, Bin; Liu, Hui-Ping

2010-06-01

299

Quantitation of Absorbers in Turbid Media Using Time-Integrated Spectroscopy Based on Microscopic Beer-Lambert Law  

Microsoft Academic Search

Based on the microscopic Beer-Lambert law, two practical time-integrated spectroscopy (TIS) methods, called dual-wavelength spectroscopy method, and dual-wavelength and dual-site spectroscopy method, are described to determine the absolute concentration of an absorber in variously shaped turbid media. We demonstrate, for the first time, the validity of the TIS methods by means of experiments in which the absolute concentrations of an

Hedong Zhang; Mitsuharu Miwa; Yutaka Yamashita; Yutaka Tsuchiya

1998-01-01

300

Quantitative Determination of the Biodegradable Polymer Poly(?-hydroxybutyrate) in a Recombinant Escherichia coli Strain by Use of Mid-Infrared Spectroscopy and Multivariative Statistics  

PubMed Central

Fourier transform infrared (FTIR) spectroscopy in combination with the partial least squares (PLS) multivariative statistical technique was used for quantitative analysis of the poly(?-hydroxybutyrate) (PHB) contents of bacterial cells. A total of 237 replicate spectra from 34 samples were obtained together with gas chromatography-determined reference PHB contents. Using the PLS regression, we were able to relate the infrared spectra to the reference PHB contents, and the correlation coefficient between the measured and predicted values for the optimal model with a standard error of prediction of 1.49% PHB was 0.988. With this technique, there are no solvent requirements, sample preparation is minimal and simple, and analysis time is greatly reduced; our results demonstrate the potential of FTIR spectroscopy as an alternative to the conventional methods used for analysis of PHB in bacterial cells.

Kansiz, Mustafa; Billman-Jacobe, Helen; McNaughton, Don

2000-01-01

301

In vitro quantitative ((1))H and ((19))F nuclear magnetic resonance spectroscopy and imaging studies of fluvastatin™ in Lescol® XL tablets in a USP-IV dissolution cell.  

PubMed

Swellable polymeric matrices are key systems in the controlled drug release area. Currently, the vast majority of research is still focused on polymer swelling dynamics. This study represents the first quantitative multi-nuclear (((1))H and ((19))F) fast magnetic resonance imaging study of the complete dissolution process of a commercial (Lescol® XL) tablet, whose formulation is based on the hydroxypropyl methylcellulose (HPMC) polymer under in vitro conditions in a standard USP-IV (United States Pharmacopeia apparatus IV) flow-through cell that is incorporated into high field superconducting magnetic resonance spectrometer. Quantitative RARE ((1))H magnetic resonance imaging (MRI) and ((19))F nuclear magnetic resonance (NMR) spectroscopy and imaging methods have been used to give information on: (i) dissolution media uptake and hydrodynamics; (ii) active pharmaceutical ingredient (API) mobilisation and dissolution; (iii) matrix swelling and dissolution and (iv) media activity within the swelling matrix. In order to better reflect the in vivo conditions, the bio-relevant media Simulated Gastric Fluid (SGF) and Fasted State Simulated Intestinal Fluid (FaSSIF) were used. A newly developed quantitative ultra-fast MRI technique was applied and the results clearly show the transport dynamics of media penetration and hydrodynamics along with the polymer swelling processes. The drug dissolution and mobility inside the gel matrix was characterised, in parallel to the ((1))H measurements, by ((19))F NMR spectroscopy and MRI, and the drug release profile in the bulk solution was recorded offline by UV spectrometer. We found that NMR spectroscopy and 1D-MRI can be uniquely used to monitor the drug dissolution/mobilisation process within the gel layer, and the results from ((19))F NMR spectra indicate that in the gel layer, the physical mobility of the drug changes from "dissolved immobilised drug" to "dissolved mobilised drug". PMID:21911016

Zhang, Qilei; Gladden, Lynn; Avalle, Paolo; Mantle, Michael

2011-09-03

302

[Study on rapid quantitative analysis of the active ingredient in ABC extinguishing agent and type identification of extinguishing agent powders using near infrared spectroscopy].  

PubMed

A new quantitative method to determine the NH4H2PO4 in ABC powder extinguishing agent and to distinguish between ABC and BC powder extinguishing agents using near infrared diffuse reflectance spectroscopy is proposed. A PLS calibration model for the NH4H2PO4 content in extinguishing agent powder was established, with RMSECV = 2.1, RMSEP = 2.4. An identification model for ABC and BC powder extinguishing agents was built by SIMCA and the identification accuracy rate is 100%. This method, compared to the present standard method, has the characteristics of rapidness and easy operation, whichis fit for the quantitative analysis and type distinguishing of the fire products on site. PMID:23156767

Hu, Ai-qin; Yuan, Hong-fu; Xue, Gang; Song, Chun-feng; Li, Xiao-yu; Xie, Jin-chun

2012-08-01

303

Detection and Quantitative Analysis of Chemical Species in Hanford Tank Materials Using Raman Spectroscopy Technology: FY94Florida State University Raman Spectroscopy Report  

SciTech Connect

This report provides a summary of work completed in FY-94 by FSU to develop and investigate the feasibility of using Raman spectroscopy with Hanford tank waste materials. Raman performance impacts from sample morphology, including the effects of absorption, particle size, density, color and refractive index, are discussed. An algorithm for relative species concentration measurement from Raman data is presented. An Algorithm for applying Raman to tank waste core screening is presented and discussed. A library of absorption and Raman spectra are presented that support this work.

Reich, F.R.

1997-08-11

304

Electron paramagnetic resonance spectroscopy studies of oxidative degradation of an active pharmaceutical ingredient and quantitative analysis of the organic radical intermediates using partial least-squares regression.  

PubMed

Electron paramagnetic resonance (EPR) spectroscopy was used to study the radical species formed during the oxidation of an active pharmaceutical ingredient in the solid state. It was found that the extent of radical generation correlated to the formation of an oxidative degradation product. Multifrequency EPR and electron nuclear double resonance spectroscopy gave additional information on the identity of the organic radical species involved in the oxidation process, and a mechanism was proposed for the degradation, involving the formation of both carbon-centered and peroxy radicals. The multivariate analysis technique of partial least-squares (PLS) regression was then used to determine the extent of oxidation of the active pharmaceutical ingredient from the EPR spectra. The suitability of this approach was demonstrated from its application to a series of standards. The conventional approach for the quantitative analysis of EPR spectra is to measure the peak height or to perform double integration of the spectral region containing the signal of interest. Both of these methods have intrinsic errors associated with them, particularly for weak EPR signals with a poor signal-to-noise ratio or a sloping background response. The results obtained showed that greatly improved quantitation was obtained using the PLS regression approach. PMID:16408946

Williams, Helen Elizabeth; Loades, Victoria Catherine; Claybourn, Mike; Murphy, Damien Martin

2006-01-15

305

Analytical Application of Laser Excited Shpol'Skii Spectroscopy: Direct Identification and Quantitation of Polynuclear Aromatic Compounds.  

National Technical Information Service (NTIS)

The object of the present work is to develop a broader application base for laser exicted Shpol'skii spectroscopy. Potential problems that may emerge are identified and solutions are provided. An atlas of reference spectra useful for the selective identif...

A. E. Elsaid

1986-01-01

306

Analytical application of laser excited shpol'skii spectroscopy: direct identification and quantitation of polynuclear aromatic compounds  

SciTech Connect

The object of the present work is to develop a broader application base for laser exicted Shpol'skii spectroscopy. Potential problems that may emerge are identified and solutions are provided. An atlas of reference spectra useful for the selective identification of individual polycyclic aromatic hydrocarbons (PAHs) has been completed. 210 refs., 83 figs., 5 tabs. (PLG)

Elsaid, A.E.

1986-01-01

307

Quantitative Differential Effects of Rhodamine 123 on Normal Cells and Human Colon Cancer Cells by Magnetic Resonance Spectroscopy  

Microsoft Academic Search

Rhodamine 123 is a lipophilic cationic compound that is selectively taken up by cancer cell mitochondria. This compound is toxic to epithelial cancer cells in vitro and displays significant anticancer activity in vivo. However, the mechanism of action of rhodamine 123 in intact, actively metabolizing cell preparations is unknown. We have used 3~p. and laC- nuclear magnetic resonance spectroscopy to

Samuel Singer; Leo J. Neuringer; William G. Thiily; Lan Bo Chen

1993-01-01

308

Direct, non-destructive quantitative measurement of an active pharmaceutical ingredient in an intact capsule formulation using Raman spectroscopy  

Microsoft Academic Search

The active pharmaceutical ingredient (ambroxol) in an intact capsule formulation has been non-destructively quantified using Raman spectroscopy. To improve the problem of insufficient representive sampling inherent in Raman measurements, we have employed a wide area illumination (WAI) scheme that enables much improved sample coverage through a circular excitation laser spot with a 6mm diameter. One of the anticipated sources of

Jaejin Kim; Jaegeun Noh; Hoeil Chung; Young-Ah Woo; Mark S. Kemper; Youngil Lee

2007-01-01

309

Singlet Delta Oxygen: A Quantitative Analysis Using Off-Axis Integrated-Cavity- Output-Spectroscopy (ICOS).  

National Technical Information Service (NTIS)

A new spectroscopic technique applicable to the detection of ultra- weak and for- bidden molecular transitions is presented. The method is based on off-axis integrated-cavity-output spectroscopy (ICOS). The primary goal for this research effort is to util...

J. E. Gallagher

2006-01-01

310

Near-infrared spectroscopy quantitative determination of pefloxacin mesylate concentration in pharmaceuticals by using partial least squares and principal component regression multivariate calibration.  

PubMed

Pefloxacin mesylate, a broad-spectrum antibacterial fluoroquinolone, has been widely used in clinical practice. Therefore, it is very important to detect the concentration of Pefloxacin mesylate. In this research, the near-infrared spectroscopy (NIRS) has been applied to quantitatively analyze on 108 injection samples, which was divided into a calibration set containing 89 samples and a prediction set containing 19 samples randomly. In order to get a satisfying result, partial least square (PLS) regression and principal components regression (PCR) have been utilized to establish quantitative models. Also, the process of establishing the models, parameters of the models, and prediction results were discussed in detail. In the PLS regression, the values of the coefficient of determination (R(2)) and root mean square error of cross-validation (RMSECV) of PLS regression are 0.9263 and 0.00119, respectively. For comparison, though applying PCR method to get the values of R(2) and RMSECV we obtained are 0.9685 and 0.00108, respectively. And the values of the standard error of prediction set (SEP) of PLS and PCR models are 0.001480 and 0.001140. The result of the prediction set suggests that these two quantitative analysis models have excellent generalization ability and prediction precision. However, for this PFLX injection samples, the PCR quantitative analysis model achieved more accurate results than the PLS model. The experimental results showed that NIRS together with PCR method provide rapid and accurate quantitative analysis of PFLX injection samples. Moreover, this study supplied technical support for the further analysis of other injection samples in pharmaceuticals. PMID:20299275

Xie, Yunfei; Song, Yan; Zhang, Yong; Zhao, Bing

2010-02-21

311

A Rapid and High-Throughput Quantitation Assay of the Nuclear Factor ?B Activity Using Fluorescence Correlation Spectroscopy in the Setting of Clinical Laboratories  

PubMed Central

Background Transcription factor nuclear factor-?B (NF-?B) plays a key role in the regulation of immune responses to inflammation. However, convenient assay systems to quantitate the NF-?B activity level in a timely manner are not available in the setting of clinical laboratories. Therefore, we developed a novel and high-throughput quantitative assay based on fluorescence correlation spectroscopy (FCS) to detect the NF-?B activity level in cellular nuclear extracts and evaluated the performance of this method. The basic principle of this assay is to calculate the binding fraction of NF-?B to fluorescent-labeled DNA probes, which contain NF-?B binding sites. Methods Non-fluorescent competitive probes are employed to normalize the influence of the viscosity of the nuclear extracts between samples and to eliminate the influence of nonspecific binding of the fluorescent probes. To confirm accurate quantitation, human recombinant NF-?B p50 was mixed into U937 cell nuclear extracts, and the binding fraction of the fluorescent probes to NF-?B in the mixture was calculated for quantitation. To evaluate whether this method can be applied to measure the NF-?B activity in human lymphocytes, the NF-?B activity levels of systemic inflammatory response syndrome patients during perioperative periods were measured. Results The percentage recovery was 88.9%. The coefficients of variation of the intra-assay were approximately 10%. NF-?B activity levels during the perioperative period can were successfully measured. The assay time for the FCS measurement was within 20 minutes. Conclusions This assay system can be used to quantitate NF-?B activity levels in a timely manner in the setting of hospital laboratories.

Harada, Kenu; Mikuni, Shintaro; Beppu, Hideyuki; Niimi, Hideki; Abe, Shigeki; Hano, Nobuko; Yamagata, Koichi; Kinjo, Masataka; Kitajima, Isao

2013-01-01

312

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

313

Optimization of metabolite basis sets prior to quantitation in magnetic resonance spectroscopy: an approach based on quantum mechanics  

NASA Astrophysics Data System (ADS)

High-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) is playing an increasingly important role for diagnosis. This technique enables setting up metabolite profiles of ex vivo pathological and healthy tissue. The need to monitor diseases and pharmaceutical follow-up requires an automatic quantitation of HRMAS 1H signals. However, for several metabolites, the values of chemical shifts of proton groups may slightly differ according to the micro-environment in the tissue or cells, in particular to its pH. This hampers the accurate estimation of the metabolite concentrations mainly when using quantitation algorithms based on a metabolite basis set: the metabolite fingerprints are not correct anymore. In this work, we propose an accurate method coupling quantum mechanical simulations and quantitation algorithms to handle basis-set changes. The proposed algorithm automatically corrects mismatches between the signals of the simulated basis set and the signal under analysis by maximizing the normalized cross-correlation between the mentioned signals. Optimized chemical shift values of the metabolites are obtained. This method, QM-QUEST, provides more robust fitting while limiting user involvement and respects the correct fingerprints of metabolites. Its efficiency is demonstrated by accurately quantitating 33 signals from tissue samples of human brains with oligodendroglioma, obtained at 11.7 tesla. The corresponding chemical shift changes of several metabolites within the series are also analyzed.

Lazariev, A.; Allouche, A.-R.; Aubert-Frécon, M.; Fauvelle, F.; Piotto, M.; Elbayed, K.; Namer, I.-J.; van Ormondt, D.; Graveron-Demilly, D.

2011-11-01

314

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

315

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

2013-01-11

316

The use of Fourier-transform infrared spectroscopy for the quantitative determination of glucose concentration in whole blood  

NASA Astrophysics Data System (ADS)

Fourier-transform infrared transmission spectroscopy has been used for the determination of glucose concentration in whole blood samples from 28 patients. A 4-vector partial least-squares calibration model, using the spectral range 950-1200 cm-1, yielded a standard-error-of-prediction of 0.59 mM for an independent test set. For blood samples from a single patient, we found that the glucose concentration was proportional to the difference between the values of the second derivative spectrum at 1082 cm-1 and 1093 cm-1. This indicates that spectroscopy at these two specific wavenumbers alone could be used to determine the glucose concentration in blood plasma samples from a single patient, with a prediction error of 0.95 mM.

Shen, Y. C.; Davies, A. G.; Linfield, E. H.; Elsey, T. S.; Taday, P. F.; Arnone, D. D.

2003-07-01

317

Establishing the gas phase dimerization of niobium(V) fluoride and tantalum(V) fluoride by quantitative Raman spectroscopy  

Microsoft Academic Search

The vapors of NbF5 and TaF5 have been investigated by Raman spectroscopy in the temperature range 475–675K and at total pressures from ?0.1 to ?4.0atm. The temperature and pressure dependence of the spectra is indicative of equilibrium shifts between monomer and associated (polymer) gaseous species. The intensities of Raman bands, which were characteristic of the various species present, were exploited

S. Boghosian; E. A. Pavlatou; G. N. Papatheodorou

2005-01-01

318

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

319

Rapid evaluation and quantitative analysis of thyme, origano and chamomile essential oils by ATR-IR and NIR spectroscopy  

Microsoft Academic Search

The essential oils obtained from various chemotypes of thyme, origano and chamomile species were studied by ATR\\/FT-IR as well as NIR spectroscopy. Application of multivariate statistics (PCA, PLS) in conjunction with analytical reference data leads to very good IR and NIR calibration results. For the main essential oil components (e.g. carvacrol, thymol, ?-terpinene, ?-bisabolol and ?-farnesene) standard errors are in

Hartwig Schulz; Rolf Quilitzsch; Hans Krüger

2003-01-01

320

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

Microsoft Academic Search

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

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

2008-01-01

321

Quantitative analysis of retinol and retinol palmitate in vitamin tablets using 1 H -nuclear magnetic resonance spectroscopy  

Microsoft Academic Search

1H-NMR spectrometry was applied to the quantitative analysis of Vitamin A in four different types of vitamin tablets without any chromatographic purification or saponification. The experiment was performed analysing the H-15 resonance, which appears at ? 4.32 for retinol and ? 4.69 for retinol palmitate, well separated from other resonances in the 1H-NMR spectrum. Compounds were quantified using the relative

Young Hae Choi; Hye Kyong Kim; Erica G Wilson; Cornelis Erkelens; Ben Trijzelaar; Robert Verpoorte

2004-01-01

322

Quantitative analysis of natural rubber, polybutadiene rubber and styrene\\/butadiene rubber blends by infra-red spectroscopy  

Microsoft Academic Search

Infra-red spectra of natural rubber (NR), polybutadiene rubber (PBR) and styrene butadiene rubber (SBR) have been studied for the estimation of these polymers in ternary rubber blends. A study of different infra-red active bands suggests that the bands at 1316 Cm-1, 1379 Cm-1 and 1493 Cm-1 are most appropriate for quantitative purpose. A detailed analysis of observed data has been

V. K. Kaushik; Y. N. Sharma

1985-01-01

323

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

PubMed

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, 360nm to obtain four compounds. The purity of compounds were determined by rapid quantitative (1)H 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 (13)C (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; Nagana Gowda, G A; Marquez, Sixto; Patil, Bhimanagouda S

2013-08-16

324

The Use of Confocal Raman Spectroscopy to Quantitatively Study the Interactions Between Immersive Water and Graphene/Graphene Oxide Surfaces  

NASA Astrophysics Data System (ADS)

The unique mechanical, chemical, optical, and electrical properties of graphene allow for many potential applications in biomaterials. Understanding and quantifying the surface interactions between graphene/graphene oxide and aqueous liquid is essential for the design of such graphene-based nanocomposites. Graphene sheets were produced by the mechanical exfoliation of graphite. We have used depth Confocal Raman Spectroscopy (CRM) profiles to measure graphene wettability using a water immersive objective lens, and demonstrated how surface energy between graphene/graphene oxide and immersive aqueous liquid can be affected to simultaneously measure the depth image profiles. Contact angles were also measured to further investigate the compatibility between graphene/graphene oxide and its environment.

Narcross, Hannah; Jeon, Byung Ho; Lee, Jong-Won; Ryu, Chang Yeol

2012-02-01

325

Identification and quantitative determination of carbohydrates in ethanolic extracts of two conifers using 13C NMR spectroscopy.  

PubMed

We developed a method for the direct identification and quantification of carbohydrates in raw vegetable extracts using (13)C NMR spectroscopy without any preliminary step of precipitation or reduction of the components. This method has been validated (accuracy, precision and response linearity) using pure compounds and artificial mixtures before being applied to authentic ethanolic extracts of pine needles, pine wood and pine cones and fir twigs. We determined that carbohydrates represented from 15% to 35% of the crude extracts in which pinitol was the principal constituent accompanied by arabinitol, mannitol, glucose and fructose. PMID:18299126

Duquesnoy, Emilie; Castola, Vincent; Casanova, Joseph

2008-01-12

326

Use of FT-NIR transmission spectroscopy for the quantitative analysis of an active ingredient in a translucent pharmaceutical topical gel formulation.  

PubMed

The objective of this study was to demonstrate the use of transmission Fourier transform near-infrared (FT-NIR) spectroscopy for quantitative analysis of an active ingredient in a translucent gel formulation. Gels were prepared using Carbopol 980 with 0%, 1%, 2%, 4%, 6%, and 8% ketoprofen and analyzed with an FT-NIR spectrophotometer operated in the transmission mode. The correlation coefficient of the calibration was 0.9996, and the root mean squared error of calibration was 0.0775%. The percent relative standard deviation for multiple measurements was 0.10%. The results prove that FT-NIR can be a good alternative to other, more time-consuming means of analysis for these types of formulations. PMID:11741274

Kemper, M S; Magnuson, E J; Lowry, S R; McCarthy, W J; Aksornkoae, N; Watts, D C; Johnson, J R; Shukla, A J

2001-01-01

327

Quantitative determination of wear metals in engine oils using laser-induced breakdown spectroscopy: A comparison between liquid jets and static liquids  

NASA Astrophysics Data System (ADS)

A comparison of laser-induced breakdown spectroscopy (LIBS) sensitivity in laminar liquid jets and at the surface of a static liquid has been performed. Limits of detection (LODs) have been estimated for Na, Mg, Al, Ca, Ti, V, Cr, Mn, Ni, Fe, Cu, Zn, Mo, Ag, Cd, and Ba under similar conditions using both experimental arrangements. LODs in liquid jets are found to be four times lower on average compared to measurements at static surfaces. Data acquisition rates in jet experiments are also generally higher than for static liquids due to reduced problems with splashing effects. The use of LIBS in jets has also been investigated for quantitative analysis of used lubricants. A number of contaminants have been measured in a set of used engine oils and the results compared to analysis via ICP-AES, where a good correlation is obtained.

Yaroshchyk, Pavel; Morrison, Richard J. S.; Body, Doug; Chadwick, Bruce L.

2005-08-01

328

Nanometer-scale, quantitative composition mappings of InGaN layers from a combination of scanning transmission electron microscopy and energy dispersive x-ray spectroscopy.  

PubMed

Using elastic scattering theory we show that a small set of energy dispersive x-ray spectroscopy (EDX) measurements is sufficient to experimentally evaluate the scattering function of electrons in high-angle annular dark field scanning transmission microscopy (HAADF-STEM). We then demonstrate how to use this function to transform qualitative HAADF-STEM images of InGaN layers into precise, quantitative chemical maps of the indium composition. The maps obtained in this way combine the resolution of HAADF-STEM and the chemical precision of EDX. We illustrate the potential of such chemical maps by using them to investigate nanometer-scale fluctuations in the indium composition and their impact on the growth of epitaxial InGaN layers. PMID:23089619

Pantzas, K; Patriarche, G; Troadec, D; Gautier, S; Moudakir, T; Suresh, S; Largeau, L; Mauguin, O; Voss, P L; Ougazzaden, A

2012-10-22

329

Quantitative determination of the oxidation state of iron in biotite using x-ray photoelectron spectroscopy: II. In situ analyses  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) was used to determine Fe(III)/{Sigma}Fe in individual biotite crystals in thin sections of ten metapelites and one syenite. The in situ XPS analyses of Fe(III)/{Sigma}Fe in biotite crystals in the metapelites were compared with published Fe(III)/{Sigma}Fe values determined by Moessbauer spectroscopy (MS) for mineral separates from the same hand samples. The difference between Fe(III)/{Sigma}Fe by the two techniques was greatest for samples with the lowest Fe(III)/{Sigma}Fe (by MS). For eight metamorphic biotites with Fe(III)/{Sigma}Fe = 9-27% comparison of the two techniques yielded a linear correlation of r = 0.94 and a statistically acceptable fit of [Fe(III)/{Sigma}Fe]{sub xps} = [Fe(III)/{Sigma}Fe]{sub ms}. The difference between Fe(III)/{Sigma}Fe by the two techniques was greater for two samples with Fe(III)/{Sigma}Fe {le} 6% (by MS). For biotite in the syenite sample, Fe(III)/{Sigma}Fe determined by both in situ XPS and bulk wet chemistry/electron probe microanalysis were similar. This contribution demonstrates that XPS can be used to analyze bulk Fe(III)/{Sigma}Fe in minerals in thin sections when appropriate precautions taken to avoid oxidation of the near-surface during preparation of samples. 25 refs., 3 figs., 4 tabs.

Raeburn, S.P. [Pennsylvania State Univ., University Park, PA (United States)]|[Lehigh Univ., Bethlehem, PA (United States); Ilton, E.S. [Lehigh Univ., Bethlehem, PA (United States); Veblen, D.R. [Johns Hopkins Univ., Baltimore, MD (United States)

1997-11-01

330

Quantitative determination of nutrient content in poultry manure by near infrared spectroscopy based on artificial neural networks.  

PubMed

Excessively applied manure contains a considerable amount of nutrient content such as nitrogen and phosphorus that could potentially pollute groundwater and soil. The present paper evaluated the use of nonlinear regression methods, such as artificial neural networks (ANN), for developing near infrared reflectance spectroscopy calibration models to predict nutrient content in poultry manure. Four representative nutrient ingredients (ammonia nitrogen, AN; total potassium, TK; total nitrogen, TN; total phosphorus, TP) in poultry manure were selected for evaluating ANN feasibility using 91 diverse samples in which three-fourths of the samples were used as a training set and one-fourth as a validation set. The performance of the ANN models was compared with the partial least squares (PLS) models. We found that the ANN models for all 4 nutrient contents consistently gave better predictions than PLS models. The ratios of prediction to deviation of 2.62 (AN), 1.51 (TK), 2.75 (TN), and 2.01 (TP) with the PLS models were improved to 3.02 (AN), 1.74 (TK), 3.41 (TN), and 2.71 (TP) with the corresponding ANN models. These findings demonstrated that the near infrared reflectance spectroscopy model based on the ANN method may be an appropriate tool to predict nutrient content in poultry manure. PMID:19903946

Chen, L J; Xing, L; Han, L J

2009-12-01

331

Quantitative speciation of Mn-bearing particulates emitted from autos burning (methylcyclopentadienyl)manganese tricarbonyl-added gasolines using XANES spectroscopy  

SciTech Connect

The chemical nature of Mn-containing particulates emitted from (methylcyclopentadienyl)manganese tricarbonyl-added gasoline engines has been elucidated using Mn K-edge X-ray absorption fine structure (XAFS) spectroscopy. Edge shift data from the X-ray absorption near-edge structure (SANES) spectra showed that the average Mn valence in these particulates is {approximately}2.2. Using a principal component analysis (PCA) algorithm, the number and type of probable species contained in these particulates were determined to be three, consisting of Mn{sub 3}O{sub 4}, MnSO{sub 4}{sm_bullet}H{sub 2}O, and a divalent manganese phosphate, Mn{sub 5}(PO{sub 4})[PO{sub 3}(OH)]{sub 2}{sm_bullet}4H{sub 2}O. The proportions of these Mn phases in each particulate sample were evaluated quantitatively using least-squares fitting (LSF) of the experimental XANES spectra with linear combinations of these principal component (model compound) spectra. Two groups of Mn-bearing particulates may be distinguished: group I having 4--9 wt % of Mn{sub 3}O{sub 4} and exhibiting a single intense first major absorption maximum at the Mn K-edge and group II containing 15--22 wt % of Mn{sub 3}O{sub 4} and exhibiting a doublet absorption maximum at lower intensity. Fourier transforms of the EXAFS signals were found to corroborate the XANES results. This study clearly establishes XANES spectroscopy, in combination with PCA and LSF, as a quantitative analytical tool for speciation of dilute and/or amorphous multicomponent environmental materials not easily attainable with conventional methods.

Ressler, T.; Wong, J.; Roos, J.; Smith, I.L.

2000-03-15

332

Quantitative data on blood flow during tumor PDT obtained by laser Doppler spectroscopy in the hen's egg test system  

NASA Astrophysics Data System (ADS)

Oxygen supply is the most important requirement of type II photodynamic reactions. Prerequisite in photodynamic tumor therapy is an intact tumor blood flow during irradiation. Most photosensitizers destroy tumor vessels due to accumulation in endothelial cells. As a prerequisite to develop novel photosensitizing drugs an in-vivo test system is required to quantitatively assess for inertness of those sensitizers to the blood supply. We adapted and further developed a system capable of measuring the relative oxygen supply to heterotransplanted tumors on the yolk sac membrane (YSM) of fertilized chicken eggs.

Vervoorts, Anja; Rood, H. A.; Klotz, Marcus; Moser, Joerg G.; Rosenbruch, Martin

1995-01-01

333

Quantitative 3.0T MR Spectroscopy Reveals Decreased Creatine Concentration in the Dorsolateral Prefrontal Cortex of Patients with Social Anxiety Disorder  

PubMed Central

Background The brain biochemical changes of social anxiety have not been clarified although there have been a limited number of MR spectroscopic studies which utilized metabolite/creatine ratios. Present study aimed to explore the alteration of absolute metabolite concentration in social anxiety disorder using quantitative MR spectroscopy. Materials and Methods With a 3.0T MR scanner, single voxel MR spectroscopy (stimulated echo acquisition mode, TR/TE/TM?=?2000/20/16 ms) was performed in the left dorsolateral prefrontal cortex and related regions of nine medication-free patients with social anxiety disorder and nine controls. Absolute metabolite concentration was calculated using tissue water as the internal reference and corrected for the partial volume of cerebrospinal fluid. Results In the left dorsolateral prefrontal cortex, the N-acetyl aspartate/creatine ratio of patients was significantly higher than that of controls, and this was due to the decrease of creatine concentration instead of the increase of N-acetyl aspartate concentration. Furthermore, the creatine concentration of the left dorsolateral prefrontal cortex was negatively correlated with the scores of Liebowitz social anxiety scale. Conclusions The alteration of creatine level in the left dorsolateral prefrontal cortex suggests abnormal energy metabolism and correlates with symptom severity in social anxiety disorder. And metabolite concentration is preferable to metabolite/creatine ratio for the investigation of individual, absolute metabolite changes in this region of social anxiety disorder.

Nie, Xiaojing; Wu, Qizhu; Li, Jun; Zhang, Wei; Huang, Xiaoqi; Gong, Qiyong

2012-01-01

334

Quantitative assessment of the hepatic pharmacokinetics of the antimicrobial sitafloxacin in humans using in vivo 19F magnetic resonance spectroscopy  

PubMed Central

Aims To measure hepatic concentrations of the fluorine-containing antimicrobial, sitafloxacin, using in vivo 19F magnetic resonance spectroscopy (MRS). Methods Data were acquired from eight healthy subjects at 2, 5, 8 and 24 h following doses of 500 mg day?1 for 5 days using a 1H/19F surface coil in a 1.5T clinical MR system. Tissue water was used as a reference. Results Estimated liver concentrations at 2 h were 15.0 ± 4.0 µg ml?1 (mean ± 95% CI), compared with 3.54 ± 0.58 µg ml?1 in plasma (n = 6), and fell below threshold concentrations (2 µg ml?1) by 24 h. Conclusions 19F MRS is able to detect and quantify sitafloxacin in the liver. There was no evidence for the hepatic retention of the drug.

Payne, Geoffrey S; Collins, David J; Loynds, Peter; Mould, Graham; Murphy, Philip S; Dzik-Jurasz, Andrzej S K; Kessar, Preminda; Haque, Nazneen; Yamaguchi, Masayuki; Atarashi, Shogo; Leach, Martin O

2005-01-01

335

Quantitative evaluation of multiple adulterants in roasted coffee by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and chemometrics.  

PubMed

The current study presents an application of Diffuse Reflectance Infrared Fourier Transform Spectroscopy for detection and quantification of fraudulent addition of commonly employed adulterants (spent coffee grounds, coffee husks, roasted corn and roasted barley) to roasted and ground coffee. Roasted coffee samples were intentionally blended with the adulterants (pure and mixed), with total adulteration levels ranging from 1% to 66% w/w. Partial Least Squares Regression (PLS) was used to relate the processed spectra to the mass fraction of adulterants and the model obtained provided reliable predictions of adulterations at levels as low as 1% w/w. A robust methodology was implemented that included the detection of outliers. High correlation coefficients (0.99 for calibration; 0.98 for validation) coupled with low degrees of error (1.23% for calibration; 2.67% for validation) confirmed that DRIFTS can be a valuable analytical tool for detection and quantification of adulteration in ground, roasted coffee. PMID:24054633

Reis, Nádia; Franca, Adriana S; Oliveira, Leandro S

2013-06-14

336

Quantitative NMR spectroscopy of complex technical mixtures using a virtual reference: chemical equilibria and reaction kinetics of formaldehyde-water-1,3,5-trioxane.  

PubMed

Quantitative 1H NMR spectroscopy was used to study chemical equilibria and reaction kinetics of both the formation and decomposition of 1,3,5-trioxane in aqueous formaldehyde solutions. The reaction was homogeneously catalyzed with up to 0.10 g g(-1) sulfuric acid at temperatures between 360 and 383 K so that most of the experiments had to be carried out pressurized. The studied mixtures were complex due to the formation of methylene glycol and poly(oxymethylene) glycols in aqueous formaldehyde and the presence of considerable amounts of ionized species. Most common internal standards are decomposed by the hot sulfuric acid and external standards were not applicable using the flow NMR probe or pressurizable NMR sample tubes. Therefore, for the quantification of the small trioxane signals, a novel procedure was applied, in which electronically generated NMR signals were used as highly stable Virtual References (VR). The NMR decoupler channel with wave-form generator was used as the source of the reference signal, which was irradiated into the probe using the lock coil. Details on the experimental procedure are presented. It is shown that the presented method yields reliable quantitative reaction data for the complex studied mixtures. PMID:16773212

Maiwald, Michael; Grützner, Thomas; Ströfer, Eckhard; Hasse, Hans

2006-05-12

337

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

338

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

339

Stimulated Raman scattering in natural crystals of SrSO4, BaSO4 and PbSO4: High-order Stokes and anti-Stokes generation with single-wavelength UV, visible, and near-IR excitation, as well as cascaded up-conversion nonlinear ? (3)? ? (3) lasing effects under dual-wavelength picosecond collinear coherent pumping  

NASA Astrophysics Data System (ADS)

Orthorhombic crystals of SrSO4, BaSO4, and PbSO4, known as natural crystals celestine, barite, and anglesite, were found to be attractive ? (3)-active nonlinear optical materials. High-order Stokes and anti-Stokes picosecond generation that spans almost two octaves has been recorded with single-wavelength laser excitation in the UV, visible, and near-IR ranges. All recorded Raman induced lasing components were identified and attributed to the SRS-promoting vibration modes of the studied crystals ( ? SRS?999 cm-1 for SrSO4, ? SRS?985 cm-1 for BaSO4 and ? SRS?977 cm-1 for PbSO4). Under dual-wavelength ( ? f1=1.06415 ?m + ? f2=0.53207 ?m) collinear coherent picosecond pumping several new manifestations of cascaded ? (3)? ? (3) nonlinear up-conversion lasing effects were observed in BaSO4 and SrSO4 crystals. We classify all three studied sulfate crystals as promising SRS-active materials for Raman laser frequency converters and as efficient ? (3)-crystals that efficiently generate Stokes and anti-Stokes frequency combs, which can enable experiments of ultra-short pulse syntheses.

Kaminskii, A. A.; Bohatý, L.; Becker, P.; Rhee, H.; Eichler, H. J.; Lux, O.; Koltashev, V. V.

2011-11-01

340

Quantitative NMR spectroscopy of supramolecular complexes: Dynamic side pores in ClpP are important for product release  

PubMed Central

The highly conserved, 300-kDa cylindrical protease ClpP is an important component of the cellular protein quality machinery. It consists of 14 subunits arranged into two heptameric rings that enclose a large chamber containing the protease active sites. ClpP associates with ClpX and ClpA ATPases that unfold and translocate substrates into the protease catalytic chamber through axial pores located at both ends of the ClpP cylinder. Although the pathway of substrate delivery is well established, the pathway of product release is unknown. Here, we use recently developed transverse relaxation optimized spectroscopy (TROSY) of methyl groups to show that the interface between the heptameric rings exchanges between two structurally distinct conformations. The conformational exchange process has been quantified by magnetization exchange and methyl TROSY relaxation dispersion experiments recorded between 0.5°C and 40°C, so that the thermodynamic properties for the transition could be obtained. Restriction of the observed motional freedom in ClpP through the introduction of a cysteine linkage results in a protease where substrate release becomes significantly slowed relative to the rate observed in the reduced enzyme, suggesting that the observed motions lead to the formation of transient side pores that may play an important role in product release.

Sprangers, Remco; Gribun, Anna; Hwang, Peter M.; Houry, Walid A.; Kay, Lewis E.

2005-01-01

341

Quantitative determination of the oxidation state of iron in biotite using x-ray photoelectron spectroscopy: I. Calibration  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) analyses of Fe(III)/{Sigma}Fe were calibrated with nine single crystals of biotite of known Fe(III)/{Sigma}Fe content. Peak shape parameters for the component Fe{sup 2+} and Fe{sup 3+} Fe 3p peaks were obtained by a constrained lease squares fitting method that minimized the difference between Fe(III)/{Sigma}Fe determined by XPS and wet chemistry/electron microprobe (WCEM) analyses. Fe{sup 2+} and Fe{sup 3+} peak separation was estimated from the separation of minima in the second derivative of Fe 3p spectra. The single set of derived peak parameters yielded a good linear correlation (r = 0.87) between XPS and WCEM values over the sample displaying progressive oxidation during XPS analysis resulted in Fe{sup 2} and Fe{sup 3+} component peak shapes largely consistent with the constrained least squares fitting methods. Beam damage, which appeared to be restricted to three single crystals with low {Sigma}Fe, low Fe/Mg, and high Fe(II)/{Sigma}Fe, caused increases in Fe(III)/{Sigma}Fe that were proportional to the duration of sample exposure. 60 refs., 6 figs., 7 tabs.

Raeburn, S.P. [Pennsylvania State Univ., University Park, PA (United States); Ilton, E.S. [Lehigh Univ., Bethlehem, PA (United States); Veblen, D.R. [Johns Hopkins Univ., Baltimore, MD (United States)

1997-11-01

342

Quantitative one-dimensional imaging using picosecond dual-broadband pure-rotational coherent anti-Stokes Raman spectroscopy.  

PubMed

We employ picosecond dual-broadband pure-rotational coherent anti-Stokes Raman spectroscopy (CARS) in a one-dimensional (1D) imaging configuration. Temperature and O(2):N(2) concentration ratios are measured along a 1D line of up to 12 mm in length. The images consist of up to 330 individual rotational CARS (RCARS) spectra, corresponding to 330 spatially resolved volume elements in the probe volume. Signal levels are sufficient for the collection of single-laser-pulse images at temperatures of up to approximately 1200 K and shot-averaged images at flame temperatures, demonstrated at 2100 K. The precision of picosecond pure-rotational 1D imaging CARS is assessed by acquiring a series of 100 single-laser-pulse images in a heated flow of N(2) from 410 K-1200 K and evaluating a single volume element for temperature in each image. Accuracy is demonstrated by comparing temperatures from the evaluated averaged spectra to thermocouple readings in the heated flow. Deviations from the thermocouple of <30 K in the evaluated temperature were found at up to 1205 K. Accuracy and single-shot precision are compared to those reported for single-point nanosecond dual-broadband pure-RCARS and nanosecond 1D vibrational CARS. PMID:21509070

Kliewer, Christopher J; Gao, Yi; Seeger, Thomas; Patterson, Brian D; Farrow, Roger L; Settersten, Thomas B

2011-04-20

343

Quantitative analysis of toxic metals lead and cadmium in water jet by laser-induced breakdown spectroscopy  

SciTech Connect

Laser-induced breakdown spectroscopy (LIBS) has been applied to the analysis of toxic metals Pb and Cd in Pb(NO{sub 3}){sub 2} and Cd(NO{sub 3}){sub 2}.4H{sub 2}O aqueous solutions, respectively. The plasma is generated by focusing a nanosecond Nd:YAG ({lambda}=1064 nm) laser on the surface of liquid in the homemade liquid jet configuration. With an assumption of local thermodynamic equilibrium (LTE), calibration curves of Pb and Cd were obtained at different delay times between 1 to 5 {mu}s. The temporal behavior of limit of detections (LOD) was investigated and it is shown that the minimum LODs for Pb and Cd are 4 and 68 parts in 10{sup 6} (ppm), respectively. In order to demonstrate the correctness of the LTE assumption, plasma parameters including plasma temperature and electron density are evaluated, and it is shown that the LTE condition is satisfied at all delay times.

Cheri, M. Sadegh; Tavassoli, S. H.

2011-03-20

344

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

NASA Astrophysics Data System (ADS)

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.

Litvin, Valentina A.; Minaev, Boris F.

2013-05-01

345

Application of LCModel for quality control and quantitative in vivo 1H MR spectroscopy by short echo time STEAM sequence.  

PubMed

The linear combination of model spectra (LCModel) calculation of a parameter for long-term quality control, kT, was introduced, representing the ratio of the temporal and nominal intensities of CH3 groups of lactate and acetate in a quality control phantom. This procedure is a part of the quality assurance of the scanner using fully automatic measurement and calculation of kT parameters, and utilizing Shewhart regulation control charts for continuous evaluation of the magnetic resonance (MR) scanner setting. The application of the kT parameter for the correction of in vivo data increases the precision of molar concentration determination by about 4%. This was tested by the quantitative in vivo MR determination of the molar concentrations of 13 prominent metabolites (N-acetylaspartate (NAA), N-acetylaspartylglutamate, creatine and phosphocreatine (Cr), choline-containing compounds (Cho), myo-inositol, scyllo-inositol, gamma-aminobutyric acid, glutamine, glutamate, glucose, lactate, alanine, taurine) in the white matter and hippocampus of the brain in groups of volunteers, using a short echo time stimulated echo acquisition mode sequence (echo time = 10 ms) and the LCModel technique. The repeatability of the measurement of prominent metabolites such as NAA, Cr and Cho was found to be around 10% (relative standard deviation, n = 6); precision in a group of volunteers (n = 20 and 28, respectively) was in the range of approximately 13-20%. For other metabolites, which are measured with a lower signal-to-noise ratio, the precision can be much lower. PMID:10697221

Hájek, M; Burian, M; Dezortová, M

2000-02-01

346

A comparison of single particle tracking and temporal image correlation spectroscopy for quantitative analysis of endosome motility.  

PubMed

Single particle tracking (SPT) is becoming a standard method to extract transport parameters from time-lapse image sequences of fluorescent vesicles in living cells. Another method to obtain these data is temporal image correlation spectroscopy (TICS), but this method is less often used for measurement of intracellular vesicle transport. Here, we present an extensive comparison of SPT and TICS. First we examine the effect of photobleaching, shading and noise on SPT and TICS analysis using simulated image sequences. To this end, we developed a simple photophysical model, which relates spatially varying illumination intensity to the bleaching propensity and fluorescence intensity of the moving particles. We found that neither SPT nor TICS are affected by photobleaching per se, but the transport parameters obtained by both methods are sensitive to the signal-to-noise ratio. In addition, the number of obtained trajectories in SPT is affected by noise. Diffusion constants determined by TICS are significantly overestimated when large immobile fluorescent structures are present in the image sequences, while the opposite is true for SPT. To improve the performance of both techniques, we compare three different methods for image denoising. Appropriate denoising significantly reduced the effect of noise and of immobile structures on both methods. Shape fluctuations of simulated particles had a more pronounced effect on TICS than on SPT analysis. In denoised images of fluorescent beads or cytosolic vesicles containing fluorescent protein NPC2 in human skin fibroblast cells, the transport parameters acquired by SPT and TICS were comparable emphasizing the value of both analysis methods. PMID:24102535

Lund, F W; Wüstner, D

2013-09-19

347

Quantitative determination of dielectric thin-film properties on product wafers using infrared reflection-absorption spectroscopy  

SciTech Connect

Process monitoring of borophosphosilicate glass (BPSG) dielectric thin films used in the manufacture of microelectronic devices is currently performed using multivariate calibration models developed from transmission infrared (IR) spectra of the films deposited on undoped monitor Si wafers. It would more be desirable to monitor the BPSG deposition on the actual product or device wafers. Because product wafers are opaque in the IR, reflection rather than transmission spectroscopy must be used to monitor the BPSG films deposited on product wafers. In this article, we demonstrate, for the first time, that IR reflection spectra of product wafers can be used to monitor the boron and phosphorus contents of the film and the film thickness to a precision that is comparable to that found for IR analysis of BPSG deposited on monitor wafers. The cross-validated standard errors of prediction of 0.11 wtthinsp{percent}, 0.11 wtthinsp{percent}, and 3 nm for B, P, and thickness, respectively, were achieved using multivariate partial least squares (PLS) models applied to the IR reflectance spectra obtained from reference product wafers. The prediction abilities were found to be independent of the position of the infrared spectrum on a given device and independent of which devices of the same structure were examined. The multivariate calibration models could be used to predict the B and P contents and film thickness of BPSG on device structures of different types and even for devices of different feature sizes if the PLS models were adjusted for slope and intercept differences. Therefore, the time and expense of generating calibrations for new device structures can be greatly reduced by the use of a small number of reference samples of the new devices to estimate the required slope and intercept adjustments for the models. {copyright} {ital 1998 American Vacuum Society.}

Niemczyk, T.M.; Zhang, L. [Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Haaland, D.M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0342 (United States); Radigan, K.J. [National Semiconductor Corporation, Santa Clara, California 95052 (United States)

1998-11-01

348

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

349

Scanning reflectance spectroscopy (380-730 nm) on varved sediments of Lake Silvaplana, Swiss Alps: a novel method for high-resolution quantitative climate reconstructions  

NASA Astrophysics Data System (ADS)

We systematically explore the potential of scanning in-situ reflectance spectroscopy in the visible spectrum (380 - 730 nm) as a novel tool for quantitative, high-resolution (2 mm) climate reconstructions that are well-calibrated against and validated with local meteorological data. Varved Lake Silvaplana (south-eastern Switzerland) is chosen as a case study, because (i) the chronology (varve counting corroborated with documented flood layers back to AD 1177) is very accurate, (ii) the mineralogical and geochemical composition of the sediments are very well understood, (iii) long meteorological data series are available for calibration and verification and (iv) independent reconstructions are available for comparison. This allows us to assess the performance and skills of the novel method on instrumental and longer time scales. First, we summarised the individual reflectance spectra with six spectral features (variables). According to principal components and redundancy analysis (PCA, RDA), the six variables reflect the mineralogical composition of the sediments (mainly biotite, illite and chlorite). Individual and combined variables (multiple linear regression) were calibrated against mean instrumental June to September (JJAS) temperature data (AD 1864 - 1950) and tested for their performance (root mean square error of prediction, RMSEP). The best calibration model was based on three variables (Trough590-730, Min690 and Min 480), explains ~84% of the variance of the meteorological data (1864 - 1950) and has a Leave-One-Out RMSEP of 0.1°C). The JJAS temperature reconstruction back to AD 1177 is in good agreement with two fully independent temperature reconstructions from documentary (back to AD 1500) and tree-ring width data confirming the high performance of the scanning reflectance-spectroscopy method and reconstruction. All the major tropical volcanic eruptions (negative forcing) appear as multi-annual negative summer temperature anomalies that were particularly pronounced if combined with solar minima.

Grosjean, Martin; Trachsel, Mathias; Kamenik, Christian; Rein, Bert

2010-05-01

350

Microscopic emission and reflectance thermal infrared spectroscopy: instrumentation for quantitative in situ mineralogy of complex planetary surfaces.  

PubMed

The diversity of investigations of planetary surfaces, especially Mars, using in situ instrumentation over the last decade is unprecedented in the exploration history of our solar system. The style of instrumentation that landed spacecraft can support is dependent on several parameters, including mass, power consumption, instrument complexity, cost, and desired measurement type (e.g., chemistry, mineralogy, petrology, morphology, etc.), all of which must be evaluated when deciding an appropriate spacecraft payload. We present a laboratory technique for a microscopic emission and reflectance spectrometer for the analysis of martian analog materials as a strong candidate for the next generation of in situ instruments designed to definitively assess sample mineralogy and petrology while preserving geologic context. We discuss the instrument capabilities, signal and noise, and overall system performance. We evaluate the ability of this instrument to quantitatively determine sample mineralogy, including bulk mineral abundances. This capability is greatly enhanced. Whereas the number of mineral components observed from existing emission spectrometers is high (often >5 to 10 depending on the number of accessory and alteration phases present), the number of mineral components at any microscopic measurement spot is low (typically <2 to 3). Since this style of instrument is based on a long heritage of thermal infrared emission spectrometers sent to orbit (the thermal emission spectrometer), sent to planetary surfaces [the mini-thermal emission spectrometers (mini-TES)], and evaluated in laboratory environments (e.g., the Arizona State University emission spectrometer laboratory), direct comparisons to existing data are uniquely possible with this style of instrument. The ability to obtain bulk mineralogy and atmospheric data, much in the same manner as the mini-TESs, is of significant additional value and maintains the long history of atmospheric monitoring for Mars. Miniaturization of this instrument has also been demonstrated, as the same microscope objective has been mounted to a flight-spare mini-TES. Further miniaturization of this instrument is straightforward with modern electronics, and the development of this instrument as an arm-mounted device is the end goal. PMID:23670748

Edwards, C S; Christensen, P R

2013-04-10

351

Fluorescence correlation spectroscopy analysis for accurate determination of proportion of doubly labeled DNA in fluorescent DNA pool for quantitative biochemical assays.  

PubMed

Fluorescent double-stranded DNA (dsDNA) molecules labeled at both ends are commonly produced by annealing of complementary single-stranded DNA (ssDNA) molecules, labeled with fluorescent dyes at the same (3' or 5') end. Because the labeling efficiency of ssDNA is smaller than 100%, the resulting dsDNA have two, one or are without a dye. Existing methods are insufficient to measure the percentage of the doubly-labeled dsDNA component in the fluorescent DNA sample and it is even difficult to distinguish the doubly-labeled DNA component from the singly-labeled component. Accurate measurement of the percentage of such doubly labeled dsDNA component is a critical prerequisite for quantitative biochemical measurements, which has puzzled scientists for decades. We established a fluorescence correlation spectroscopy (FCS) system to measure the percentage of doubly labeled dsDNA (PDL) in the total fluorescent dsDNA pool. The method is based on comparative analysis of the given sample and a reference dsDNA sample prepared by adding certain amount of unlabeled ssDNA into the original ssDNA solution. From FCS autocorrelation functions, we obtain the number of fluorescent dsDNA molecules in the focal volume of the confocal microscope and PDL. We also calculate the labeling efficiency of ssDNA. The method requires minimal amount of material. The samples have the concentration of DNA in the nano-molar/L range and the volume of tens of microliters. We verify our method by using restriction enzyme Hind III to cleave the fluorescent dsDNA. The kinetics of the reaction depends strongly on PDL, a critical parameter for quantitative biochemical measurements. PMID:23920090

Hou, Sen; Sun, Lili; Wieczorek, Stefan A; Kalwarczyk, Tomasz; Kaminski, Tomasz S; Holyst, Robert

2013-07-18

352

Rheological characterization of UV/visible photopolymerizable coatings  

NASA Astrophysics Data System (ADS)

The present work is focalized on the development and rheological characterization of innovative UV-photopolymerizable coatings. The experimental formulations were mainly intended for the surface protection of porous stones, in particular those belonging to Apuliam monumental, archeological and historical constructions. Several formulations able to polymerize through UV radiations were developed and analyzed with a parallel plates rheomether as function of composition and shear rate.

Corcione, C. Esposito; Frigione, M.

2012-07-01

353

UV-visible emissions in the atmosphere of Ganymede  

NASA Astrophysics Data System (ADS)

In the frame of the future JUICE mission, we began to calculate the emissions of the Ganymede atmosphere. After the effects of the solar UV flux, we investigate the effects of the magnetospheric electrons coming from the jovian magnetosphere into the Ganymede atmosphere.

Barthelemy, M.; Cessateur, G.; Mbeka-Kabuiku, L.; Lilensten, J.

2012-09-01

354

Surface Water Quality Risk Assessment Through UV-Visible Spectrophotometer  

Microsoft Academic Search

2 Abstract: The present study is aimed at assessing the water quality index (WQI) for the surface and ground water in the study area of Attock City, Punjab, Pakistan. This has been determined by collecting 30 wate r samples each from boreholes, municipal water supply and Kabul River. For calculating the WQI, the following parameters have been considered: temperature, pH,

Muhammad Qasim; Abida K Khan; Rehana Rashid; Sadia Nasreen; Qaisar Mahmood; Jamil Khan

2009-01-01

355

UVMag: a UV+visible spectropolarimeter to study stellar magnetospheres  

NASA Astrophysics Data System (ADS)

In the last decade magnetic fields have been detected in basically all types of stars. These discoveries gave rise to innovative studies on the mapping of magnetic fields and on their impact on stellar environment. To go even further, the UVMag international consortium proposes to combine UV and visible spectropolarimetry. The UV domain allows us to study stellar winds, while the optical domain allows us to study the stellar surface. With UV and visible spectropolarimetry we can then study magnetospheres as a whole and do this over a complete stellar rotation period thanks to a space mission. UV and visible spectropolarimetry can of course also address many other stellar physics issues.

Neiner, C.

2012-12-01

356

A meta-classifier for detecting prostate cancer by quantitative integration of in vivo magnetic resonance spectroscopy and magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Recently, in vivo Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy (MRS) have emerged as promising new modalities to aid in prostate cancer (CaP) detection. MRI provides anatomic and structural information of the prostate while MRS provides functional data pertaining to biochemical concentrations of metabolites such as creatine, choline and citrate. We have previously presented a hierarchical clustering scheme for CaP detection on in vivo prostate MRS and have recently developed a computer-aided method for CaP detection on in vivo prostate MRI. In this paper we present a novel scheme to develop a meta-classifier to detect CaP in vivo via quantitative integration of multimodal prostate MRS and MRI by use of non-linear dimensionality reduction (NLDR) methods including spectral clustering and locally linear embedding (LLE). Quantitative integration of multimodal image data (MRI and PET) involves the concatenation of image intensities following image registration. However multimodal data integration is non-trivial when the individual modalities include spectral and image intensity data. We propose a data combination solution wherein we project the feature spaces (image intensities and spectral data) associated with each of the modalities into a lower dimensional embedding space via NLDR. NLDR methods preserve the relationships between the objects in the original high dimensional space when projecting them into the reduced low dimensional space. Since the original spectral and image intensity data are divorced from their original physical meaning in the reduced dimensional space, data at the same spatial location can be integrated by concatenating the respective embedding vectors. Unsupervised consensus clustering is then used to partition objects into different classes in the combined MRS and MRI embedding space. Quantitative results of our multimodal computer-aided diagnosis scheme on 16 sets of patient data obtained from the ACRIN trial, for which corresponding histological ground truth for spatial extent of CaP is known, show a marginally higher sensitivity, specificity, and positive predictive value compared to corresponding CAD results with the individual modalities.

Viswanath, Satish; Tiwari, Pallavi; Rosen, Mark; Madabhushi, Anant

2008-04-01

357

Time-resolved rapid-scan Fourier transform infrared difference spectroscopy on a noncyclic photosystem: rhodopsin photointermediates from Lumi to Meta II.  

PubMed

The visual pigment rhodopsin has been extensively studied for the kinetics of its photointermediates by various spectroscopic methods. Unlike such archaeal retinal proteins as bacteriorhodopsin, visual rhodopsin does not thermally recover its dark state after photoexcitation, which precludes repeated excitation of a single sample and thereby complicates time-resolved experiments. Kinetic data on the late rhodopsin photointermediates have so far been available mainly from time-resolved ultraviolet (UV)-visible spectroscopy, but not from Fourier transform infrared (FTIR) spectroscopy. The latter has the advantage of being informative of structural changes of both chromophore and protein, but does not allow the highly reproducible, automated sample exchange procedures available to UV-visible spectroscopy. Using rapid-scan FTIR difference spectroscopy, we obtained time-resolved data sets that were analyzed by a maximum entropy inverse Laplace-transform. Covering the time range from 8 ms to 15 s at temperatures of 0 and -7 degrees C, the transitions from the Lumi to the Meta I and from the Meta I to the Meta II photoproduct states could be resolved. In the transition from Meta I to Meta II, our data reveal a partial deprotonation of the retinal Schiff base preceding the conformational change of the receptor protein to Meta II. The technique and the results are discussed in regard to its advantages as well as its limitations. PMID:16721790

Lüdeke, Steffen; Lórenz Fonfría, Víctor A; Siebert, Friedrich; Vogel, Reiner

2006-10-01

358

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

NASA Astrophysics Data System (ADS)

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 perform traditional unknown analyses, and as groups, they study an aquatic ecosystem simulated by a trout aquarium. Ecosystem analyses include the important chemical components of the nitrogen cycle, dissolved oxygen, and alkalinity. In addition to examining the aquatic system, trout are removed temporarily from the aquarium for analysis of lipid and moisture content using near infrared (NIR) spectroscopy. For the ecosystem investigation, students also determine costs of analyses and conduct quality-control studies. At the completion of the course, students are well versed in classical methods of analysis as well as educated on the relevance of modern technology, including up-to-date instrumentation and sophisticated multivariate calibration and prediction procedures. Course assessment results are summarized in the paper.

Houghton, Tracy P.; Kalivas, John H.

2000-10-01

359

Quantitative measurements by Fourier-transform infrared spectroscopy of toxic gas production during inhibition of JP-8 fires by CF(3)Br and C(3)F(7)H.  

PubMed

Fourier-transform infrared spectroscopy is used to monitor gases generated during chemical inhibition of JP-8 fuel pool fires burning in air. Gas samples are taken from a location that approximates the position of an individual who is using a handheld extinguisher to subdue the fire. These gas samples are flowed through a 10-m path-length multipass optical cell placed in the sample beam of a Fourier-transform infrared spectrometer. Gas samples are analyzed before and during application of C(3)F(7)H (trade name FM200) and CF(3)Br (Halon 1301) to the fire. It is shown that application of these halogenated hydrocarbons to JP-8 pool fires produces significant quantities of acid gases (HF and HBr) and of CF(2)O. A calculation of the concentrations (in parts in 10(6)) of these gases and other gaseous combustion products, based on observed absorbances, is presented. We believe this is the first quantitative simultaneous measurement of HF, HBr, HCl, and CF(2)O production during chemical inhibition of real fires. PMID:21102803

Modiano, S H; McNesby, K L; Marsh, P E; Bolt, W; Herud, C

1996-07-20

360

Quantitative measurements by Fourier-transform infrared spectroscopy of toxic gas production during inhibition of JP-8 fires by CF3Br and C3F7H  

NASA Astrophysics Data System (ADS)

Fourier-transform infrared spectroscopy is used to monitor gases generated during chemical inhibition of JP-8 fuel pool fires burning in air. Gas samples are taken from a location that approximates the position of an individual who is using a handheld extinguisher to subdue the fire. These gas samples are flowed through a 10-m path-length multipass optical cell placed in the sample beam of a Fourier-transform infrared spectrometer. Gas samples are analyzed before and during application of C3F7H (trade name FM200) and CF3Br (Halon 1301) to the fire. It is shown that application of these halogenated hydrocarbons to JP-8 pool fires produces significant quantities of acid gases (HF and HBr) and of CF2O. A calculation of the concentrations (in parts in 10 6) of these gases and other gaseous combustion products, based on observed absorbances, is presented. We believe this is the first quantitative simultaneous measurement of HF, HBr, HCl, and CF2O production during chemical inhibition of real fires.

Modiano, Steven H.; McNesby, Kevin L.; Marsh, Paul E.; Bolt, William; Herud, Craig

1996-07-01

361

Combined surface-enhanced Raman spectroscopy biotags and microfluidic platform for quantitative ratiometric discrimination between noncancerous and cancerous cells in flow  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman spectroscopy (SERS) biotags (SBTs) that carry peptides as cell recognition moieties were made from polymer-encapsulated silver nanoparticle dimers, infused with unique Raman reporter molecules. We previously demonstrated their potential use for identification of malignant cells, a central goal in cancer research, through a multiplexed, ratiometric method that can confidently distinguish between cancerous and noncancerous epithelial prostate cells in vitro based on receptor overexpression. Progress has been made toward the application of this quantitative methodology for the identification of cancer cells in a microfluidic flow-focusing device. Beads are used as cell mimics to evaluate the devices. Cells (and beads) are simultaneously incubated with two sets of SBTs while in suspension, then injected into the device for laser interrogation under flow. Each cell event is characterized by a composite Raman spectrum, deconvoluted into its single components to ultimately determine their relative contribution. We have found that using SBTs ratiometrically can provide cell identification in flow, insensitive to normal causes of uncertainty in optical measurements such as variations in focal plane, cell concentration, autofluorescence, and turbidity.

Pallaoro, Alessia; Hoonejani, Mehran R.; Braun, Gary B.; Meinhart, Carl; Moskovits, Martin

2013-01-01

362

Quantitative measurements of loss on ignition in iron ore using laser-induced breakdown spectroscopy and partial least squares regression analysis.  

PubMed

Laser-induced breakdown spectroscopy (LIBS) and partial least squares regression (PLSR) have been applied to perform quantitative measurements of a multiple-species parameter known as loss on ignition (LOI), in a combined set of run-of-mine (ROM) iron ore samples originating from five different iron ore deposits. Global calibration models based on 65 samples and their duplicates from all the deposits with LOI ranging from 0.5 to 10 wt% are shown to be successful for prediction of LOI content in pressed pellets as well as bulk ore samples. A global independent dataset comprising a further 60 samples was used to validate the model resulting in the best validation R(2) of 0.87 and root mean square error of prediction (RMSEP) of 1.1 wt% for bulk samples. A validation R(2) of 0.90 and an RMSEP of 1.0 wt% were demonstrated for pressed pellets. Data preprocessing is shown to improve the quality of the analysis. Spectra normalization options, automatic outlier removal and automatic continuum background correction, which were used to improve the performance of the PLSR method, are discussed in detail. PMID:21144150

Yaroshchyk, Pavel; Death, David L; Spencer, Steven J

2010-12-01

363

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

364

Quantitative determination of polyphosphate in sediments using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and partial least squares regression.  

PubMed

Phosphorus (P) is a major cause of eutrophication and subsequent loss of water quality in freshwater ecosystems. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. Despite the broad relevance of polyphosphate (Poly-P) in bioremediation and P release processes in the environment, its quantification is not yet well developed for sediment samples. Current methods possess significant disadvantages because of the difficulties associated with using a single extractant to extract a specific P compound without altering others. A fast and reliable method to estimate the quantitative contribution of microorganisms to sediment P release processes is needed, especially when an excessive P accumulation in the form of polyphosphate (Poly-P) occurs. Development of novel approaches for application of emerging spectroscopic techniques to complex environmental matrices such as sediments significantly contributes to the speciation models of P mobilization, biogeochemical nutrient cycling and development of nutrient models. In this study, for the first time Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy in combination with partial least squares (PLS) was used to quantify Poly-P in sediments. To reduce the high absorption matrix components in sediments such as silica, a physical extraction method was developed to separate sediment biological materials from abiotic particles. The aim was to achieve optimal separation of the biological materials from sediment abiotic particles with minimum chemical change in the sample matrix prior to ATR-FTIR analysis. Using a calibration set of 60 samples for the PLS prediction models in the Poly-P concentration range of 0-1 mg g(-1) d.w. (dry weight of sediment) (R(2) = 0.984 and root mean square error of prediction RMSEP = 0.041 at Factor-1) Poly-P could be detected at less than 50 ?g g(-l) d.w. Using this technique, there is no solvent extraction or chemical treatment required, sample preparation is minimal and simple, and the analysis time is greatly reduced. The results from this study demonstrated the potential of ATR FT-IR spectroscopy as an alternative method to study Poly-P in sediments. PMID:22801463

Khoshmanesh, Aazam; Cook, Perran L M; Wood, Bayden R

2012-08-21

365

Parallel ?-sheet vibrational couplings revealed by 2D IR spectroscopy of an isotopically labeled macrocycle: quantitative benchmark for the interpretation of amyloid and protein infrared spectra.  

PubMed

Infrared spectroscopy is playing an important role in the elucidation of amyloid fiber formation, but the coupling models that link spectra to structure are not well tested for parallel ?-sheets. Using a synthetic macrocycle that enforces a two stranded parallel ?-sheet conformation, we measured the lifetimes and frequency for six combinations of doubly (13)C?(18)O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequencies of the labels ranged from 1585 to 1595 cm(-1), with the largest frequency shift occurring for in-register amino acids. The 2D IR spectra of the coupled isotope labels were calculated from molecular dynamics simulations of a series of macrocycle structures generated from replica exchange dynamics to fully sample the conformational distribution. The models used to simulate the spectra include through-space coupling, through-bond coupling, and local frequency shifts caused by environment electrostatics and hydrogen bonding. The calculated spectra predict the line widths and frequencies nearly quantitatively. Historically, the characteristic features of ?-sheet infrared spectra have been attributed to through-space couplings such as transition dipole coupling. We find that frequency shifts of the local carbonyl groups due to nearest neighbor couplings and environmental factors are more important, while the through-space couplings dictate the spectral intensities. As a result, the characteristic absorption spectra empirically used for decades to assign parallel ?-sheet secondary structure arises because of a redistribution of oscillator strength, but the through-space couplings do not themselves dramatically alter the frequency distribution of eigenstates much more than already exists in random coil structures. Moreover, solvent exposed residues have amide I bands with >20 cm(-1) line width. Narrower line widths indicate that the amide I backbone is solvent protected inside the macrocycle. This work provides calculated and experimentally verified couplings for parallel ?-sheets that can be used in structure-based models to simulate and interpret the infrared spectra of ?-sheet containing proteins and protein assemblies, such as amyloid fibers. PMID:23113791

Woys, Ann Marie; Almeida, Aaron M; Wang, Lu; Chiu, Chi-Cheng; McGovern, Michael; de Pablo, Juan J; Skinner, James L; Gellman, Samuel H; Zanni, Martin T

2012-11-09

366

Sodium and potassium released from burning particles of brown coal and pine wood in a laminar premixed methane flame using quantitative laser-induced breakdown spectroscopy.  

PubMed

A quantitative point measurement of total sodium ([Na](total)) and potassium ([K](total)) in the plume of a burning particle of Australian Loy Yang brown coal (23 ± 3 mg) and of pine wood pellets (63 ± 3 mg) was performed using laser-induced breakdown spectroscopy (LIBS) in a laminar premixed methane flame at equivalence ratios ( U ) of 1.149 and 1.336. Calibration was performed using atomic sodium or potassium generated by evaporation of droplets of sodium sulfite (Na(2)SO(3)) or potassium sulfate (K(2)SO(4)) solutions seeded into the flame. The calibration compensated for the absorption by atomic alkalis in the seeded flame, which is significant at high concentrations of solution. This allowed quantitative measurements of sodium (Na) and potassium (K) released into the flame during the three phases of combustion, namely devolatilization, char, and ash cooking. The [Na](total) in the plume released from the combustion of pine wood pellets during the devolatilization was found to reach up to 13 ppm. The maximum concentration of total sodium ([Na](max)M(total)) and potassium ([K](max)(total)) released during the char phase of burning coal particles for ? = 1.149 was found to be 9.27 and 5.90 ppm, respectively. The [Na](max)(total) and [K](max)(total) released during the char phase of burning wood particles for ? = 1.149 was found to be 15.1 and 45.3 ppm, respectively. For the case of ? = 1.336, the [Na](max)(total) and [K](max)(total) were found to be 13.9 and 6.67 ppm during the char phase from burning coal particles, respectively, and 21.1 and 39.7 ppm, respectively, from burning wood particles. The concentration of alkali species was higher during the ash phase. The limit of detection (LOD) of sodium and potassium with LIBS in the present arrangement was estimated to be 29 and 72 ppb, respectively. PMID:21639991

Hsu, Li-Jen; Alwahabi, Zeyad T; Nathan, Graham J; Li, Yu; Li, Z S; Aldén, Marcus

2011-06-01

367

Quantitative time-resolved vibrational sum frequency generation spectroscopy as a tool for thin film kinetic studies: new insights into oleic Acid monolayer oxidation.  

PubMed

Environmental air-water interfaces are often covered by thin films of surface-active organic substances that play an important role for air-sea gas exchange and aerosol aging. Surface-sensitive vibrational sum frequency generation (VSFG) spectroscopy has been widely used to study the static structure of organic monolayers serving as simple model systems of such films. Probably due to the difficulties to correlate the SFG signal intensity with the surface concentration, corresponding time-resolved studies of surface reactions are scarce. In this study, quantitative time-resolved measurements have been performed on the oleic acid monolayer ozonolysis, which is considered a benchmark system for investigating the reactivity and fate of unsaturated natural organics. Surface concentration calibration data have been obtained by combining the pressure-area isotherm and VSFG spectra acquisition such that the 2D phase behavior of the oleic acid film could be properly taken into account. In contrast to literature reports, surface-active oxidation products were found to be negligible and do not interfere with the VSFG measurements. A pseudo-first-order kinetic analysis of the time-resolved data yielded a bimolecular rate constant of k2(oleic acid + O3 ? products) = (1.65 ± 0.64) × 10(-16) cm(3) molecules(-1) s(-1), corresponding to an uptake coefficient of ? = (4.7 ± 1.8) × 10(-6). This result is in very good agreement with most recent monolayer measurements based on alternative methods and underlines the reliability of the time-resolved VSFG approach. PMID:23808968

Kleber, Joscha; Laß, Kristian; Friedrichs, Gernot

2013-08-07

368

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

2012-08-25

369

The influence of multivariate analysis methods and target grain size on the accuracy of remote quantitative chemical analysis of rocks using laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) was used to quantitatively analyze 195 rock slab samples with known bulk chemical compositions, 90 pressed-powder samples derived from a subset of those rocks, and 31 pressed-powder geostandards under conditions that simulate the ChemCam instrument on the Mars Science Laboratory Rover (MSL), Curiosity. The low-volatile (<2 wt.%) silicate samples (90 rock slabs, corresponding powders, and 22 geostandards) were split into training, validation, and test sets. The LIBS spectra and chemical compositions of the training set were used with three multivariate methods to predict the chemical compositions of the test set. The methods were partial least squares (PLS), multilayer perceptron artificial neural networks (MLP ANNs) and cascade correlation (CC) ANNs. Both the full LIBS spectrum and the intensity at five pre-selected spectral channels per major element (feature selection) were used as input data for the multivariate calculations. The training spectra were supplied to the algorithms without averaging ( i.e. five spectra per target) and with averaging ( i.e. all spectra from the same target averaged and treated as one spectrum). In most cases neural networks did not perform better than PLS for our samples. PLS2 without spectral averaging outperformed all other procedures on the basis of lowest quadrature root mean squared error (RMSE) for both the full test set and the igneous rocks test set. The RMSE for PLS2 using the igneous rock slab test set is: 3.07 wt.% SiO 2, 0.87 wt.% TiO 2, 2.36 wt.% Al 2O 3, 2.20 wt.% Fe 2O 3, 0.08 wt.% MnO, 1.74 wt.% MgO, 1.14 wt.% CaO, 0.85 wt.% Na 2O, 0.81 wt.% K 2O. PLS1 with feature selection and averaging had a higher quadrature RMSE than PLS2, but merits further investigation as a method of reducing data volume and computation time and potentially improving prediction accuracy, particularly for samples that differ significantly from the training set. Precision and accuracy were influenced by the ratio of laser beam diameter (˜490 ?m) to grain size, with coarse-grained rocks often resulting in lower accuracy and precision than analyses of fine-grained rocks and powders. The number of analysis spots that were normally required to produce a chemical analysis within one standard deviation of the true bulk composition ranged from ˜10 for fine-grained rocks to >20 for some coarse-grained rocks.

Anderson, Ryan B.; Morris, Richard V.; Clegg, Samuel M.; Bell, James F.; Wiens, Roger C.; Humphries, Seth D.; Mertzman, Stanley A.; Graff, Trevor G.; McInroy, Rhonda

2011-10-01

370

Structural, UV-visible, and electrochemical studies on 2,3-dicyano-5,6-di-2-pyridylpyrazine, [(CN)2Py2Pyz], related species and its complexes [(CN)2Py2PyzMCl2] (M = Pt(II), Pd(II)).  

PubMed

2,3-Dicyano-5,6-di-2-pyridylpyrazine, [(CN)(2)Py(2)Pyz], which autocyclotetramerizes to give the macrocycle tetrakis[5,6-di(2-pyridyl)-2,3-pyrazino]porphyrazine, [Py(8)TPyzPzH(2)], bearing externally four dipyridinopyrazine fragments, reacts with bis(benzonitrile)dichloroplatinum(II), [(C(6)H(5)CN)(2)PtCl(2)], in CH(3)CN, affording the monometalated species [(CN)(2)Py(2)PyzPtCl(2)]. Single-crystal X-ray work on this compound shows that Pt(II) is bound to [(CN)(2)Py(2)Pyz] through the two pyridine N atoms ("py-py" coordination) in a way similar to that found for its monopalladium analogue, [(CN)(2)Py(2)PyzPdCl(2)]. Cyclic voltammetry of [(CN)(2)Py(2)PyzPtCl(2)] and [(CN)(2)Py(2)PyzPdCl(2)] in nonaqueous media (pyridine, DMSO, and DMF) indicates that the electron-withdrawing effect of the coordinated PtCl(2) and PdCl(2) units results in an initial one-electron reduction (E(1/2) = -0.60 and -0.54 V vs SCE in DMSO, respectively), which is easier by 0.25-0.30 V than the unmetalated [(CN)(2)Py(2)Pyz] (first reduction: E(1/2) = -0.87 V vs SCE). These electrochemical data are analyzed along with new results for a selected number of related pyrazine and 2,3-dicyanopyrazine molecules as well as earlier reported data on the mono- and bis-N-methylated derivatives [(CN)(2)Py(2-Mepy)Pyz](+) and [(CN)(2)(2-Mepy)(2)Pyz](2+), with these latter species being formed by reaction of the precursor [(CN)(2)Py(2)Pyz] with methyl iodide or p-toluensulfonate. The data in this study are also compared to electrochemical data previously reported for a triad of palladium(II) porphyrazine macrocycles obtained from the precursor [(CN)(2)Py(2)Pyz], i.e., [Py(8)TPyzPzPd], the corresponding pentanuclear complex [(PdCl(2))(4)Py(8)TPyzPzPd] (presenting "py-py" coordination at the dipyridinopyrazine fragments), and the octacation [(2-Mepy)(8)TPyzPzPd](8+) (N-methylated at the pyridine rings). Thin-layer UV-visible spectra of singly reduced [(CN)(2)Py(2)Pyz](-) and its metalated analogues, [(CN)(2)Py(2)PyzPtCl(2)](-) and [(CN)(2)Py(2)PyzPdCl(2)](-), were measured in pyridine, DMF, and DMSO and show pi-pi* transitions, as well as unusually intense absorptions in the near-IR region (500-900 nm) of the spectrum. PMID:19583212

Cai, Xiaohui; Donzello, Maria Pia; Viola, Elisa; Rizzoli, Corrado; Ercolani, Claudio; Kadish, Karl M

2009-08-01

371

Identification and quantitative determination of eudesmane-type acids from the essential oil of Dittrichia viscosa sp. viscosa using 13C-NMR spectroscopy.  

PubMed

A procedure that allows the identification and quantitative determination of eudesmane-type acids in the acidic part of the essential oil of Dittrichia viscosa sp. viscosa is described. The method involves the computer-aided analysis of the 13C-NMR spectrum of the mixture without the requirement of previous separation or derivatisation. The quantitative procedure was verified with costic acid standard and applied to three other acids which possess the same eudesmane framework. PMID:15997846

Blanc, Marie-Cécile; Bradesi, Pascale; Casanova, Joseph

372

A quantitative differentiation method for plastic bags by infrared spectroscopy, thickness measurement and differential scanning calorimetry for tracing the source of illegal drugs  

Microsoft Academic Search

Fifty shopping bags, commonly encountered in the packaging of drug doses, were characterized by thickness measurements, infrared spectroscopy and differential scanning calorimetry. By these very straightforward and inexpensive techniques, without sample preparation, nearly all the considered samples could be discriminated. Ninety-seven percent of the possible pairs of white, apparently similar dull polymer films were differentiated. The rather large degree of

Valerio Causin; Carla Marega; Pietro Carresi; Sergio Schiavone; Antonio Marigo

2006-01-01

373

Nanoscale Investigation of the Degradation Mechanism of a Historical Chrome Yellow Paint by Quantitative Electron Energy Loss spectroscopy Mapping of Chromium Species.  

PubMed

Getting the picture: The investigation of 100?year old chrome yellow paint by transmission electron microscopy and spectroscopy has led to the identification of four types of core-shell particles. This nanoscale investigation has allowed a mechanism to be proposed for the darkening of some bright yellow colors in Van Gogh's paintings (e.g. in Falling leaves (Les Alyscamps), 1888). PMID:24039036

Tan, Haiyan; Tian, He; Verbeeck, Jo; Monico, Letizia; Janssens, Koen; Van Tendeloo, Gustaaf

2013-09-13

374

Quantitative combination of volumetric MR imaging and MR spectroscopy data for the discrimination of meningiomas from metastatic brain tumors by means of pattern recognition  

Microsoft Academic Search

The analysis of information derived from magnetic resonance imaging (MRI) and spectroscopy (MRS) has been identified as an important indicator for discriminating among different brain pathologies. The purpose of this study was to investigate the efficiency of the combination of textural MRI features and MRS metabolite ratios by means of a pattern recognition system in the task of discriminating between

Pantelis Georgiadis; Spiros Kostopoulos; Dionisis Cavouras; Dimitris Glotsos; Ioannis Kalatzis; Koralia Sifaki; Menelaos Malamas; Ekaterini Solomou; George Nikiforidis

2011-01-01

375

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

376

Springtime Arctic ground-based spectroscopy of O3 and related trace gases at Eureka, Canada - Part 1: Evaluation of the analysis method and comparison with infrared measurements  

NASA Astrophysics Data System (ADS)

For the first time in spring 1999 the ground-based UV-visible zenith-sky measurements of stratospheric gases were performed at Environment Canada's Arctic Stratospheric Ozone Observatory (ASTRO) located at Eureka, Nunavut, Canada (80.05° N, 86.42° W, 610 m a.s.l.). The University of Toronto UV-visible ground-based spectrometer (UT-GBS) has been deployed for nine years afterwards at Eureka to measure ozone and NO2 total columns by using sunlight scattered from the zenith sky during spring, when the conditions leading to polar ozone depletion develop. During spring 2000, elevated OClO slant column densities were also measured for the first time. First dedicated analysis of UT-GBS measurements applying two independent differential optical absorption spectroscopy algorithms was performed on spectra recorded during spring 2000. The resulting ozone and NO2 total columns agreed to 4% and 5% or better, respectively. Also, first four years of UT-GBS results (1999-2003) were compared with those made by ozonesondes and by the Meteorogical Service of Canada Fourier transform infrared spectrometer (MSC FTS) at ASTRO, which has been operated by Canada's Department of Environment for measuring the total columns of several stratospheric gases. The comparison of UT-GBS and MSC FTS ozone total columns proved to be better than 5% for the periods when both instruments were viewing similar air masses.

Farahani, E.; Strong, K.; Mittermeier, R. L.; Fast, H.; van Roozendael, M.; Fayt, C.

2009-02-01

377

In vitro quantitative 1 H and 19 F nuclear magnetic resonance spectroscopy and imaging studies of fluvastatin™ in Lescol® XL tablets in a USP-IV dissolution cell  

Microsoft Academic Search

Swellable polymeric matrices are key systems in the controlled drug release area. Currently, the vast majority of research is still focused on polymer swelling dynamics. This study represents the first quantitative multi-nuclear (1H and 19F) fast magnetic resonance imaging study of the complete dissolution process of a commercial (Lescol® XL) tablet, whose formulation is based on the hydroxypropyl methylcellulose (HPMC)

Qilei Zhang; Lynn Gladden; Paolo Avalle; Michael Mantle

378

Analytical, Nutritional and Clinical Methods Section Quantitative analysis of a-pinene and b-myrcene in mastic gum oil using FT-Raman spectroscopy  

Microsoft Academic Search

a-Pinene and b-myrcene are compounds that are contained in mastic gum in high concentrations.The b-myrcene percentage determines the marketability of mastic gums.The chemical composition of mastic gum oil of a representative resin quality was evaluated by gas chromatography-mass spectrometry (GC-MS) technique.FT-Raman spectroscopy, based on band intensity measurements, was used for the determination of a-pinene and b-myrcene content in mastic gum.Bands

D. Daferera; C. Pappas; P. A. Tarantilis; M. Polissiou

379

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

380

Quantitative ?-HCNCH: determination of the glycosidic torsion angle ? in RNA oligonucleotides from the analysis of CH dipolar cross-correlated relaxation by solution NMR spectroscopy  

Microsoft Academic Search

A novel NMR pulse sequence is introduced to determine the glycosidic torsion angle ? in 13C,15N-labeled oligonucleotides. The quantitative ?-HCNCH measures the dipolar cross-correlated relaxation rates $$\\\\Gamma_{{\\\\rm C6H6,C1}^{\\\\prime}{\\\\rm H1}^{\\\\prime}}^{\\\\rm DD,DD}$$ (pyrimidines) and $$\\\\Gamma_{{\\\\rm C8H8,C1}^{\\\\prime}{\\\\rm H1}^{\\\\prime}}^{\\\\rm DD,DD}$$ (purines). Cross-correlated relaxation rates of a 13C,15N-labeled RNA 14mer containing a cUUCGg tetraloop were determined and yielded ?-angles that agreed remarkably well with data

Jörg Rinnenthal; Christian Richter; Jan Ferner; Elke Duchardt; Harald Schwalbe

2007-01-01

381

Quantitative Analysis of Microstructure in Polysiloxanes Using High Resolution Si29 NMR Spectroscopy: Investigation of Lot Variability in the LVM97 and HVM97 PDMS/PDPS Copolymers  

SciTech Connect

The quantitative analysis of microstructure and sequence distribution in polysiloxane copolymers using high-resolution solution {sup 29}Si NMR is reported. Copolymers containing dimethylsiloxane (DMS) and diphenysiloxane (DPS) monomer units prepared with either high vinyl content (HVM) or low vinyl content (LVM) were analyzed. The average run length (R{sub exp}), the number average sequence length (l{sub A}, l{sub B}), along with the various linkage probabilities (p{sub AA}, p{sub AB}, p{sub BA}, and p{sub BB}) were determined for different production lots of the LVM97 and HVM97 samples to address the lot variability of microstructure in these materials.

ALAM, TODD M.

2002-11-01

382

Metabolic, pathologic, and genetic analysis of prostate tissues: quantitative evaluation of histopathologic and mRNA integrity after HR-MAS spectroscopy.  

PubMed

The impact of high-resolution magic angle spinning (HR-MAS) spectroscopy on the histopathologic and mRNA integrity of human prostate tissues was evaluated. Forty prostate tissues were harvested at transrectal ultrasound (TRUS) guided biopsy (n?=?20) or radical prostatectomy surgery (n?=?20), snap-frozen on dry ice, and stored at -80°C until use. Twenty-one samples (n?=?11 biopsy, n?=?10 surgical) underwent HR-MAS spectroscopy prior to histopathologic and cDNA microarray analysis, while 19 control samples (n?=?9 biopsy, n?=?10 surgical) underwent only histopathologic and microarray analysis. Frozen tissues were sectioned at 14-µm intervals and placed on individual histopathology slides. Every 8th slide was stained with hematoxylin and eosin (H&E) and used to target areas of predominantly epithelial tissue on the remaining slides for mRNA integrity and cDNA microarray analysis. Histopathologic integrity was graded from 1 (best) to 5 (worst) by two 'blinded' pathologists. Histopathologic integrity scores were not significantly different for post-surgical tissues (HR-MAS vs controls); however, one pathologist's scores were significantly lower for biopsy tissues following HR-MAS while the other pathologist's scores were not. mRNA integrity assays were performed using an Agilent 2100 Bioanalyzer and the electrophoretic traces were scored with an RNA integrity number (RIN) from 1 (degraded) to 10 (intact). RIN scores were not significantly different for surgical tissues, but were significantly lower for biopsy tissues following HR-MAS spectroscopy. The isolated mRNA then underwent two rounds of amplification, conversion to cDNA, coupling to Cy3 and Cy5 dyes, microarray hybridization, imaging, and analysis. Significance analysis of microarrays (SAM) identified no significantly over- or under-expressed genes, including 14 housekeeping genes, between HR-MAS and control samples of surgical and biopsy tissues (5% false discovery rate). This study demonstrates that histopathologic and genetic microarray analysis can be successfully performed on prostate surgical and biopsy tissues following HR-MAS analysis; however, biopsy tissues are more fragile than surgical tissues. PMID:20033906

Santos, Carissa F; Kurhanewicz, John; Tabatabai, Z Laura; Simko, Jeffry P; Keshari, Kayvan R; Gbegnon, Akpene; Santos, Romelyn Delos; Federman, Scot; Shinohara, Katsuto; Carroll, Peter R; Haqq, Christopher M; Swanson, Mark G

2009-12-23

383

Metabolic, pathologic, and genetic analysis of prostate tissues: quantitative evaluation of histopathologic and mRNA integrity after HR-MAS spectroscopy  

PubMed Central

The impact of high-resolution magic angle spinning (HR-MAS) spectroscopy on the histopathologic and mRNA integrity of human prostate tissues was evaluated. Forty prostate tissues were harvested at transrectal ultrasound (TRUS) guided biopsy (n =20) or radical prostatectomy surgery (n =20), snap-frozen on dry ice, and stored at ?80°C until use. Twenty-one samples (n =11 biopsy, n =10 surgical) underwent HR-MAS spectroscopy prior to histopathologic and cDNA microarray analysis, while 19 control samples (n =9 biopsy, n =10 surgical) underwent only histopathologic and microarray analysis. Frozen tissues were sectioned at 14-?m intervals and placed on individual histopathology slides. Every 8th slide was stained with hematoxylin and eosin (H&E) and used to target areas of predominantly epithelial tissue on the remaining slides for mRNA integrity and cDNA microarray analysis. Histopathologic integrity was graded from 1 (best) to 5 (worst) by two ‘blinded’ pathologists. Histopathologic integrity scores were not significantly different for post-surgical tissues (HR-MAS vs controls); however, one pathologist’s scores were significantly lower for biopsy tissues following HR-MAS while the other pathologist’s scores were not. mRNA integrity assays were performed using an Agilent 2100 Bioanalyzer and the electrophoretic traces were scored with an RNA integrity number (RIN) from 1 (degraded) to 10 (intact). RIN scores were not significantly different for surgical tissues, but were significantly lower for biopsy tissues following HR-MAS spectroscopy. The isolated mRNA then underwent two rounds of amplification, conversion to cDNA, coupling to Cy3 and Cy5 dyes, microarray hybridization, imaging, and analysis. Significance analysis of microarrays (SAM) identified no significantly over- or under-expressed genes, including 14 housekeeping genes, between HR-MAS and control samples of surgical and biopsy tissues (5% false discovery rate). This study demonstrates that histopathologic and genetic microarray analysis can be successfully performed on prostate surgical and biopsy tissues following HR-MAS analysis; however, biopsy tissues are more fragile than surgical tissues.

Santos, Carissa F.; Kurhanewicz, John; Tabatabai, Z. Laura; Simko, Jeffry P.; Keshari, Kayvan R.; Gbegnon, Akpene; Santos, Romelyn DeLos; Federman, Scot; Shinohara, Katsuto; Carroll, Peter R.; Haqq, Christopher M.; Swanson, Mark G.

2010-01-01

384

Quantitative depth-resolved photoelectron spectroscopy analysis of the interaction of energetic oxygen ions with the beryllium-tungsten alloy Be2W  

NASA Astrophysics Data System (ADS)

The chemical reactions during the implantation of oxygen ions into a thin beryllium-tungsten alloy layer on a beryllium substrate and subsequent annealing are investigated by depth-resolved chemical analysis using X-ray photoelectron spectroscopy. By using variable photon energies at a synchrotron, identical kinetic energies of the photoelectrons from the different core levels are selected. This enables a chemical analysis at identical depth intervals for all core levels. From these sets of photoelectron spectra chemically resolved depth profiles are determined. The depth profiles allow an interpretation of the reaction and diffusion steps during implantation and annealing steps. This leads to a detailed understanding of the complex processes in a multi-component solid.

Köppen, M.; Oberkofler, M.; Riesch, J.; Schmid, K.; Vollmer, A.; Linsmeier, Ch.

2013-07-01

385

A quantitative study of valence electron transfer in the skutterudite compound CoP3 by combining x-ray induced Auger and photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

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 CoP3. 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 CoP3 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.

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

2007-06-01

386

Improvement of the inverse-gated-decoupling sequence for a faster quantitative analysis of various samples by 13C NMR spectroscopy  

NASA Astrophysics Data System (ADS)

The inverse-gated-decoupling sequence enables quantitative 1H decoupled 13C spectra to be obtained. We modified this sequence so as to obtain the same result in less time for molecules containing carbons with various relaxation properties. For that, we determined the optimal 13C longitudinal-magnetization initial value for a faster relaxation while 1H decoupler is stopped. This value can be calculated precisely via the nuclear Overhauser effects, the longitudinal relaxation times, together with the determination of the relaxation rate constants of carbons while 1H are out of equilibrium. A supplementary delay of 1H decoupling and/or a series of selective pulses applied at the beginning of the recovery delay allow an acceleration of 13C longitudinal relaxation. We applied this method to the molecule of vanillin. The simultaneous quantification of all carbons was carried out with a recovery delay divided by two compared to the usual sequence.

Giraudeau, Patrick; Baguet, Evelyne

2006-05-01

387

Quantitative estimates of vascularity in a collagen-based cell scaffold containing basic fibroblast growth factor by non-invasive near-infrared spectroscopy for regenerative medicine  

NASA Astrophysics Data System (ADS)

Successful tissue regeneration required both cells with high proliferative and differentiation potential and an environment permissive for regeneration. These conditions can be achieved by providing cell scaffolds and growth factors that induce angiogenesis and cell proliferation. Angiogenenis within cell scaffolds is typically determined by histological examination with immunohistochemical markers for endothelium. Unfortunately, this approach requires removal of tissue and the scaffold. In this study, we examined the hemoglobin content of implanted collagen-based cell scaffolds containing basic fibroblast growth factor (bFGF) in vivo by non-invasive near infrared spectroscopy (NIRS). We also compared the hemoglobin levels measured by NIRS to the hemoglobin content measured with a conventional biological assay. Non-invasive NIRS recordings were performed with a custom-built near-infrared spectrometer using light guide-coupled reflectance measurements. NIRS recordings revealed that absorbance increased after implantation of collagen scaffolds containing bFGF. This result correlated (R2=0.93) with our subsequent conventional hemoglobin assay. The NIRS technique provides a non-invasive method for measuring the degree of vascularization in cell scaffolds. This technique may be advantageous for monitoring angiogenesis within different cell scaffolds, a prerequisite for effective tissue regeneration.

Kushibiki, Toshihiro; Awazu, Kunio

2008-05-01

388

Phase coherence theory for data-mining and analysis: application studies in spectroscopy  

NASA Astrophysics Data System (ADS)

The paper investigates from the perspective of computer science the phase coherence theory (PCT) and phase coherent data-scatter (PCD-S). These techniques were originally developed for the area of optical tensiographic data mining and analysis but have a more general appplication in data mining. These develoments have recently been augmented with the engineering of a software toolkit called TraceMiner. Although the toolkit was originally devised for tensiography it was developed to perform as a generic data mining and analysis application with PCT, PCD-S and a range of other data mining algorithms implemented. To date the toolkit has been utilised in its main application area, tensiography, but has also been applied to UV-visible spectroscopy. This work presents a critical investigation of the general utility of PCT, PCD-S and the toolkit for data mining and analysis. A new application of PCT and the TraceMiner software toolkit to Raman spectroscopy is presented with discussion of the relevant measures and the information provided by the toolkit. This provides more insight into the generic potential of the techniques for data mining. The analysis performed on theoretical Raman data is augmented with a study of experimental Raman data. Raman spectroscopy is used for composition and fault detecton analysis in semiconductor surfaces. Finally, the utility of the PCT technique in comparison with traditional Raman spectroscopy methods is considered together with some more general applications in the field of imaging and machine vision.

Doyle, G.; McMillan, N. D.; Murtagh, F.; O'Neill, M.; Riedel, S.; Perova, T. S.; Unnikrishnan, S.; Moore, R. A.

2005-06-01

389

Quantitative analysis of the near-wall mixture formation process in a passenger car direct-injection Diesel engine by using linear Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Optimum fuel preparation and mixture formation are core issues in the development of modern direct-injection (DI) Diesel engines, as these are crucial for defining the border conditions for the subsequent combustion and pollutant formation process. The local fuel/air ratio can be seen as one of the key parameters for this optimization process, as it allows the characterization and comparison of the mixture formation quality. For what is the first time to the best of our knowledge, linear Raman spectroscopy is used to detect the fuel/air ratio and its change along a line of a few millimeters directly and nonintrusively inside the combustion bowl of a DI Diesel engine. By a careful optimization of the measurement setup, the weak Raman signals could be separated successfully from disturbing interferences. A simultaneous measurement of the densities of air and fuel was possible along a line of about 10 mm length, allowing a time- and space-resolved measurement of the local fuel/air ratio. This could be performed in a nonreacting atmosphere as well as during fired operating conditions. The positioning of the measurement volume next to the interaction point of one of the spray jets with the wall of the combustion bowl allowed a near-wall analysis of the mixture formation process for a six-hole nozzle under varying injection and engine conditions. The results clearly show the influence of the nozzle geometry and preinjection on the mixing process. In contrast, modulation of the intake air temperature merely led to minor changes of the fuel concentration in the measurement volume.

Taschek, Marco; Egermann, Jan; Schwarz, Sabrina; Leipertz, Alfred

2005-11-01

390

Quantitative analysis of the near-wall mixture formation process in a passenger car direct-injection diesel engine by using linear raman spectroscopy.  

PubMed

Optimum fuel preparation and mixture formation are core issues in the development of modern direct-injection (DI) Diesel engines, as these are crucial for defining the border conditions for the subsequent combustion and pollutant formation process. The local fuel/air ratio can be seen as one of the key parameters for this optimization process, as it allows the characterization and comparison of the mixture formation quality. For what is the first time to the best of our knowledge, linear Raman spectroscopy is used to detect the fuel/air ratio and its change along a line of a few millimeters directly and nonintrusively inside the combustion bowl of a DI Diesel engine. By a careful optimization of the measurement setup, the weak Raman signals could be separated successfully from disturbing interferences. A simultaneous measurement of the densities of air and fuel was possible along a line of about 10 mm length, allowing a time- and space-resolved measurement of the local fuel/air ratio. This could be performed in a nonreacting atmosphere as well as during fired operating conditions. The positioning of the measurement volume next to the interaction point of one of the spray jets with the wall of the combustion bowl allowed a near-wall analysis of the mixture formation process for a six-hole nozzle under varying injection and engine conditions. The results clearly show the influence of the nozzle geometry and preinjection on the mixing process. In contrast, modulation of the intake air temperature merely led to minor changes of the fuel concentration in the measurement volume. PMID:16270549

Taschek, Marco; Egermann, Jan; Schwarz, Sabrina; Leipertz, Alfred

2005-11-01

391

Entropy analysis of muscular near-infrared spectroscopy (NIRS) signals during exercise programme of type 2 diabetic patients: Quantitative assessment of muscle metabolic pattern.  

PubMed

Diabetes mellitus (DM) is a metabolic disorder that is widely rampant throughout the world population these days. The uncontrolled DM may lead to complications of eye, heart, kidney and nerves. The most common type of diabetes is the type 2 diabetes or insulin-resistant DM. Near-infrared spectroscopy (NIRS) technology is widely used in non-invasive monitoring of physiological signals. Three types of NIRS signals are used in this work: (i) variation in the oxygenated haemoglobin (O2Hb) concentration, (ii) deoxygenated haemoglobin (HHb), and (iii) ratio of oxygenated over the sum of the oxygenated and deoxygenated haemoglobin which is defined as: tissue oxygenation index (TOI) to analyze the effect of exercise on diabetes subjects. The NIRS signal has the characteristics of non-linearity and non-stationarity. Hence, the very small changes in this time series can be efficiently extracted using higher order statistics (HOS) method. Hence, in this work, we have used sample and HOS entropies to analyze these NIRS signals. These computer aided techniques will assist the clinicians to diagnose and monitor the health accurately and easily without any inter or intra observer variability. Results showed that after a one-year of physical exercise programme, all diabetic subjects increased the sample entropy of the NIRS signals, thus revealing a better muscle performance and an improved recruitment by the central nervous system. Moreover, after one year of physical therapy, diabetic subjects showed a NIRS muscular metabolic pattern that was not distinguished from that of controls. We believe that sample and bispectral entropy analysis is need when the aim is to compare the inner structure of the NIRS signals during muscle contraction, particularly when dealing with neuromuscular impairments. PMID:24075080

Molinari, Filippo; Acharya, U Rajendra; Martis, Roshan Joy; De Luca, Riccardo; Petraroli, Giuliana; Liboni, William

2013-09-07

392

Influence of the colloidal structure of dairy gels on milk fat fusion behavior: quantification of the liquid fat content by in situ quantitative proton nuclear magnetic resonance spectroscopy (isq (1) H NMR).  

PubMed

Dairy gels (DG), such as yoghurts, contain both solid and liquid fats at the time of consumption, as their temperature rises to anything between 10 and 24 °C after being introduced into the mouth at 4 °C. The mass ratio between solid and liquid fats, which depends on the temperature, impacts the organoleptic properties of DG. As the ordinary methods for determining this ratio can only be applied to samples consisting mainly in fat materials, a fat extraction step needs to be added into the analytical process when applied to DG, which prevents the study of the potential impact of their colloidal structure on milk fat fusion behavior. In situ quantitative proton nuclear magnetic resonance spectroscopy (isq (1) H NMR) was investigated as a method for direct measurements in DG: at temperatures between 20.0 and 70.0 °C, the liquid fat content and the composition of triacylglycerols of the liquid phase (in terms of alkyl chains length) were determined. Spectra of isolated milk fat also enable the quantification of the double bonds of triacylglycerols. Statistical tests showed no significant difference between isolated milk fat and milk fat inside a DG in terms of melting behavior: the fat globule membrane does not seem to have a significant influence on the fat melting behavior. PMID:23464867

Bouteille, Romain; Perez, Jeanne; Khifer, Farid; Jouan-Rimbaud-Bouveresse, Delphine; Lecanu, Bruno; This, Hervé

2013-03-06

393

In situ infrared emission spectroscopy for quantitative gas-phase measurement under high temperature reaction conditions: an analytical method for methane by means of an innovative small-volume flowing cell.  

PubMed

We have used infrared emission spectroscopy (IRES) in order to perform in situ studies under flowing gas-phase conditions. When the small-volume cell developed herein is used, we can (1) observe emission spectra from a hot gas-phase sample having an effective volume much less than one milliliter, (2) observe spectra of typical molecular species present, and (3) observe spectra of the more important molecular species down to below 10% and in some cases even as low as 1%. In addition, an analytical method has been derived in order to conduct quantitative studies under typical reaction conditions. We show that simplifications can be made in the data acquisition and handling for a direct linear correlation between band intensity and concentration with only simple background correction. The practical lower limit for methane in the present setup is approximately 0.5-1% v/v depending on the selected temperature. Our data were collected at 500, 600, and 700 degrees C, respectively. The major features of the present cell design are fairly simple and basically formed by a quartz tube (outer diameter=6 mm, inner diameter=4 mm) inside a metal pipe and two tubular ceramic heaters. This simple setup has advantages and attractive features that have extended the application of IRES to new fields and, in particular, for in situ studies of hydrocarbon reactions at different residence times at high temperature. PMID:20149274

Usseglio, Sandro; Thorshaug, Knut; Karlsson, Arne; Dahl, Ivar M; Nielsen, Claus J; Jens, Klaus-J; Tangstad, Elisabeth

2010-02-01

394

Quantitative Analysis and Characterization of DNA Immobilized on Gold.  

National Technical Information Service (NTIS)

We describe the complementary use of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy to quantitatively characterize the immobilization of thiolated (dT)25 single- stranded DNA (ssDNA) on gold. When electron attenu...

D. Y. Petrovykh H. Kimura-Suda L. J. Whitman M. J. Tarlov

2003-01-01

395

Quantitative analysis  

PubMed Central

Quantitative analysis permits the isolation of invariant relations in the study of behavior. The parameters of these relations can serve as higher-order dependent variables in more extensive analyses. These points are illustrated by reference to quantitative descriptions of performance maintained by concurrent schedules, multiple schedules, and signal-detection procedures. Such quantitative descriptions of empirical data may be derived from mathematical theories, which in turn can lead to novel empirical analyses so long as their terms refer to behavioral and environmental events. Thus, quantitative analysis is an integral aspect of the experimental analysis of behavior.

Nevin, John A.

1984-01-01

396

Quantitative fractography  

Microsoft Academic Search

In many disciplines, such as biology, botany, geology, materials science and medicine, quantitative image analysis is being used to an increasing extent. In materials science this technique makes it possible to relate the microsctructure to the mechanical properties. In this review we shall show that image analysis can be applied in a fractographic study to characterize quantitatively the morphology of

J. L. Chermant; M. Coster

1979-01-01

397

Quantitative Spectroscopy Temperature Determination in Plasmas.  

National Technical Information Service (NTIS)

Fast rising spark discharges in high pressure gas and in air and their qualification as standard light sources have been investigated. Two special types are described: A spark for exposure times in the microsecond-and one in the msec- range. The radiation...

W. Botticher H. Manthey J. Rath

1965-01-01

398

Chapter 8 Quantitation of Protein  

Microsoft Academic Search

The measurement of protein concentration in an aqueous sample is an important assay in biochemistry research and development labs for applications ranging from enzymatic studies to providing data for biopharmaceutical lot release. Spectrophotometric protein quantitation assays are methods that use UV and visible spectroscopy to rapidly determine the concentration of protein, relative to a standard, or using an assigned extinction

James E. Noble; Marc J. A. Bailey

2009-01-01

399

Spectroscopy and kinetics of weakly bound gas phase adducts of atmospheric interest  

NASA Astrophysics Data System (ADS)

A number of weakly bound adducts play important roles in atmospheric chemistry, such as DMS--OH and CS2--OH. The work comprising this dissertation involves kinetic and spectroscopic studies of adducts formed between halogen atoms and the important atmospheric trace gases CS2, CH3SCH3 (DMS), CH3I, and C2H 5I. The results reported in these studies are useful for developing an understanding of the reactivity of these species and for testing the ability of electronic structure theory and reaction rate theory to predict or rationalize any observed trends. Oxidative pathways of both alkyl halides and sulfur compounds, especially DMS, are of atmospheric interest based on the roles of these species in affecting the oxidizing capacity of the troposphere and in the formation of new particles which impact the Earth's radiation budget and climate variability. The experimental approach employed laser flash photolysis (LFP) coupled with time resolved UV-visible absorption spectroscopy (TRUVVAS) to investigate the spectroscopy and kinetics of the gas phase adducts: SCS--Cl, CH 3I--Cl, C2H5I--Cl, (CH3) 2S--Br, and (CH3)2S--I.

Dookwah-Roberts, Venus

400

Analysis of bacterial growth by UV/Vis spectroscopy and laser reflectometry  

NASA Astrophysics Data System (ADS)

This work presents a preliminary study on an experimental analysis of the lactobacillus bacterial growth in liquid medium with and without the presence of silver nanoparticles. The study aims to quantify the bactericidal effect of nanoparticles. Quantification of bacterial growth at different times was analyzed by spectroscopy UV/visible and laser reflectometry near the critical angle. From these two techniques the best results were obtained by spectroscopy, showing that as the concentration of silver nanoparticles increases, it inhibits the growth of bacteria, it only grows 63% of the population. Regarding Laser Reflectometry, the variation of reflectance near the critical angle is measured in real time. The observed results at short times are reasonable, since they indicate a gradual growth of the bacteria and the stabilization stage of the population. But at long time, the observed results show abrupt changes caused by temperature effects. The bacteria were isolated from samples taken from commercial yougurth, and cultured in MRS broth at pH 6.5, and controlled with citric acid and constant temperature of 32 °C. Separately, silver nanoparticles were synthesized at 3 °C from aqueous solutions of 1.0 mM silver nitrate and chemically reduced with sodium borohydride to 2.0 mM, with magnetic stirring.

Peña-Gomar, Mary Carmen; Viramontes-Gamboa, Gonzalo; Peña-Gomar, Grethel; Ortiz Gutiérrez, Mauricio; Hernández Ramírez, Mariano

401

Au nanoparticle arrays produced by Pulsed Laser Deposition for Surface Enhanced Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Using UV pulses from KrF excimer laser, Au targets were ablated in varying pressures of argon to deposit Au nanoparticle (NP) arrays. The morphology of these films from island structures to isolated NPs, observed by SEM and TEM, depends on the gas pressure (10-100 Pa) and pulse number keeping other deposition parameters constant. By fast imaging of the plasma with an iCCD camera at different time delays with respect to the arrival of the laser pulse, we study the plasma propagation regime and we measured its initial velocity. These data and the measured average ablated mass per pulse were introduced to the mixed propagation model to calculate the average asymptotic size of clusters grown in the plume which were compared with NP sizes from TEM measurements. UV-visible Spectroscopy revealed changes of surface plasmon resonance with respect to NP size and spatial density and distribution on the surface. Suitable wavelength to excite the localized surface plasmon was chosen to detect ultra-low concentrations of Rhodamine and Apomorphine as an application to biomedical sensors, using Surface Enhanced Raman Spectroscopy (SERS). A comparison of SERS spectra taken under identical conditions from commercial substrates and from PLD substrates show that the latter have superior performances.

Agarwal, N. R.; Neri, F.; Trusso, S.; Lucotti, A.; Ossi, P. M.

2012-09-01

402

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

SciTech Connect

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 to occur in three detectable relaxations (1/tau 1 greater than 1/tau 2 greater than 1/tau 3). The RSSF data reveal that during tau 1, the internal aldimine, E(PLP), with lambda max = 412 nm (pH 7.8), undergoes rapid conversion to two transient species, one with lambda max congruent to 420 nm and one with lambda max congruent to 460 nm. These species decay in a biphasic process to a complicated final spectrum with lambda max congruent to 350 nm and with a broad envelope of absorbance extending out to approximately 525 nm. Analysis of the time-resolved spectra establishes that the spectral changes in tau 2 are nearly identical with the spectral changes in tau 3. These findings identify the serine Schiff base (the external aldimine) as the 420 nm absorbing, highly fluorescent transient; the species with lambda max congruent to 460 nm is the delocalized carbanion (quinoidal) species derived from abstraction of the alpha proton from the external aldimine. The reaction of L-serine with beta 2 consists of two relaxations and yields a quasi-stable species with lambda max = 420 nm, in good agreement with a previous report.

Drewe, W.F. Jr.; Dunn, M.F.

1985-07-16

403

QUANTITATIVE MORPHOLOGY  

EPA Science Inventory

Abstract: In toxicology, the role of quantitative assessment of brain morphology can be understood in the context of two types of treatment-related alterations. One type of alteration is specifically associated with treatment and is not observed in control animals. Measurement ...

404

Chemical spectroscopy  

Microsoft Academic Search

The purpose of chemical spectroscopy with neutrons is to utilize the dependence of neutron scattering cross sections on isotope and on momentum transfer (which probes the spatial extent of the excitation) to understand fundamental and applied aspects of the dynamics of molecules and fluids. Chemical spectroscopy is divided into three energy ranges: vibrational spectroscopy, 25-500 MeV, for which much of

J. Eckert; T. O. Brun; A. J. Dianoux; J. Howard; J. J. Rush; J. W. White

1984-01-01

405

"Axial-Bonding"-Type Hybrid Porphyrin Arrays: Synthesis, Spectroscopy, Electrochemistry, and Singlet State Properties.  

PubMed

A series of phosphorus(V), germanium(IV), and tin(IV) porphyrin-based, "axial-bonding"-type hybrid trimers have been readily constructed by employing a new "building-block" approach. The approach is modular in nature, and it involves simple "inorganic" reactions such as axial bond formation of main group element containing porphyrins and insertion of metal/"metalloid" ions into the porphyrin cavity. The architecture of these arrays is such that, while a phosphorus(V), germanium(IV), or tin(IV) complex of meso-5,10,15,20-(tetratolyl)porphyrin forms the basal scaffolding unit, the free-base, vanadyl, cobalt(II), nickel(II), copper(II), or zinc(II) porphyrins occupy the two axial sites via an aryloxy bridge. Synthesis of an "all-phosphorus" array containing three phosphorus(V) subunits has also been accomplished. Each new porphyrin array investigated in this study has been fully characterized by various physical methods that include mass (FAB), UV-visible, infrared, fluorescence, electron spin resonance (ESR), and (1)H and (31)P nuclear magnetic resonance (NMR; 1D and 2D) spectroscopies and cyclic voltammetry. The UV-visible and ESR spectral parameters and also the redox potential data suggest that there exists no interaction between the pi-planes of the constituent monomeric porphyrins in these arrays. Detailed (1)H NMR investigations carried out with the trimers containing diamagnetic porphyrins reveal characteristic shielding/deshielding effects for the various protons on the axial porphyrin subunits. The ground state data, as probed by the spectroscopic and electrochemical techniques, collectively indicate that there exists a symmetric but nonparallel disposition of the two axial porphyrins with respect to plane of the central porphyrin. Singlet state activity of the photoactive trimers has been probed by the steady state fluorescence method with selective excitation into the bands corresponding to the two constituent monomeric species. Analysis of the fluorescence emission and excitation spectral data suggests the occurrence of electronic energy transfer as well as photoinduced electron transfer reactions in trimers endowed with free-base or zinc(II) porphyrin axial subunits. Efficiencies of the excited state processes of these trimeric arrays are shown to be dependent on the type of metal/metalloid ions present in the porphyrin crevice. PMID:11671239

Giribabu, L.; Rao, T. Anita; Maiya, Bhaskar G.

1999-11-01

406

Matrix isolation spectroscopy and the stability of polycyclic aromatics in coal ash: Final report  

SciTech Connect

Matrix Isolation Spectroscopy (MIS) overcomes some limitations of conventional molecular fluorescence and infrared (IR) spectroscopies by producing spectra having perhaps 10 times narrower spectral peaks. Analyte molecules are prevented from interacting with each other (or any other foreign molecules) because they are surrounded by an inert solid matrix (e.g., N/sub 2/, Ar, Ne, or Kr) at temperatures <20 K. For IR applications, such matrices exhibit no spectral interferences (phonon peaks occur at <85 cm/sup -1/). When interfaced with conventional gas chromatography (GC), MIS can usually resolve coeluting compounds in complex organic mixtures and is particularly effective for analysis of polycyclic aromatic compounds (PAC). Often, pretreatment is not necessary if there are <10 different compounds in the sample. Owing to the low energy throughput of MIS, combining with dispersive IR is not an effective technique, whereas combining with Fourier-transform infrared (FTIR) and ultraviolet (uv)-visible fluorescence is. Also, matrix-isolation (MI) combinations with other methods, such as electron paramagnetic resonance (EPR), Raman spectroscopy, secondary ion mass spectrometry (SIMS), and photoacoustic spectroscopy (PAS), may be useful. Laser excitation provides a sensitivity of <1 mg/kg. Resolution can be improved using a monochromatic laser, a polarized excitation source and polarized emitted fluorescence, and measuring fluorescence decay time. A separate study showed that PAC are photochemically stabilized in coal ash because of its carbonaceous matter (pie-pie bonding and porosity effect). Nonphotochemical degradation (generally oxidation) occurs for specific PAC (especially those containing a benzylic C-atom, e.g., fluorene).

Mamantov, G.; Wehry, R.L.

1987-06-01

407

Using one-dimensional (1D) and two-dimensional (2D) quantitative proton (1H) nuclear magnetic resonance spectroscopy (q NMR) for the identification and quantification of taste compounds in raw onion (Allium cepa L.) bulbs and in aqueous solutions where onion tissues are soaked.  

PubMed

Solutions obtained by soaking onion (Allium cepa L.) bulbs samples in water are frequently consumed, either directly or as part of dishes, both at home or in the food industry. However, little information is available regarding the extracted metabolites and the extraction mechanisms. In this article, the composition of raw onion extracts and of aqueous solutions where raw onion tissues were soaked was investigated directly by quantitative proton nuclear magnetic resonance spectroscopy (q (1)H NMR). The assignment of NMR signals was performed, with less than 3% (in area) of unidentified peaks. Analyses of one-dimensional (1)H NMR spectra with additional two-dimensional NMR studies showed 20 regions of interest where 3 saccharides, 17 amino acids, and 5 organic acids were detected and quantified. Resonance assignment with chemical shift was done for each saccharide, as well as for each amino acid and organic acid, with additional work on spin-spin coupling pattern and on observed and not observed correlations from correlation spectroscopy studies. Quantification of saccharides was performed and qualified by works on peak decomposition algorithms. Complementary studies by high-performance liquid chromatography, mass spectroscopy and tandem mass spectroscopy, and thin layer chromatography and preparative layer chromatography were carried out in order to validate the NMR results on identification. PMID:20972556

Tardieu, Audrey; De Man, Walter; This, Hervé

2010-10-23

408

Controlled thin layer coating of carbon nanotube-polymer composites for UV-visible light protection  

Microsoft Academic Search

A highly dispersed solution of multi-wall carbon nanotubes (MWCNT) and counterpart polymers was prepared in aqueous solution.\\u000a A thin layer coating was deposited on glass substrates by using the layer-by-layer (LBL) method. A negative charged dispersion\\u000a solution of MWCNT was obtained by oxidizing the MWCNT by immersion in nitric acid. Counterpart polymers, poly(diallydimethylammonium\\u000a chloride) (PDDA) and poly(acrylic acid) (PAA), were

Jaebeom Lee; Sang-Jun Park; Young-Kyun Moon; Soo-Hyung Kim; Kwangnak Koh

2009-01-01

409

A System for In Situ UV-Visible Illumination of Transmission Electron Microscope Samples  

NASA Astrophysics Data System (ADS)

A system for illuminating a sample in situ with visible and UV light inside a transmission electron microscope was devised to study photocatalysts. There are many factors which must be considered when designing and building such a system. These include both mechanical, optical, and electron optical considerations. Some of the restrictions posed by the electron microscope column are significant, and care must be taken not to degrade the microscope's electron optical performance, or to unduly restrict the other current capabilities of the microscope. The nature of these various design considerations is discussed in detail. A description of the system that has been added to the microscope at ASU, an FEI Tecnai F20 environmental transmission electron microscope is also given. The system includes a high brightness broadband light source with optical filters, a fiber to guide the light to the sample, and a system for precisely aligning the fiber tip. The spatial distribution and spectrum of the light reaching the sample has been characterized, and is described in detail.

Miller, Benjamin

410

DETERMINATION OF FLUNARIZINE IN RAT'S BRAIN BY LIQUID CHROMATOGRAPHY WITH UV\\/VISIBLE DETECTION  

Microsoft Academic Search

This paper describes a newly developed method to determine Flunarizine (FZ) in rat's brain by high performance liquid chromatography (HPLC) with UV\\/Vis detection.FZ was extracted by acetonitrile\\/water mixture and then analyzed by LC assay. Good extraction recovery (>90%) and linearity (r=0.9999) were determined. The precision of this method was adequate for our application. The application of this newly developed method

Ming-Ren Fuh; Yee-Fu Chan; Wynn W. H. Pan; I.-Ping Huang

1999-01-01

411

PSC and volcanic aerosol observations during EASOE by UV-visible ground-based spectrometry  

SciTech Connect

This paper presents results from ground-based spectrometry of twilight sky color in the UV and visible region, taken at four stations on the arctic circle. These stations observed the appearance of aerosol layers from the volcanic eruption of Mt. Pinatubo in mid 1991. The aerosol density increased steadily at lower stratospheric levels, and spread inside the polar vortex. These stations only observed one high altitude PSC during this winter campaign.

Sarkissian, A.; Pommereau, J.P.; Goutail, F. (Service d'Aeronomie, Verrieres-le-Buisson (France)); Kyro, E. (Finnish Meteorological Institute, Sodankylae (Finland))

1994-06-22

412

Spectral reflectance and transmittance in dental enamel for UV, visible, and NIR light  

NASA Astrophysics Data System (ADS)

For this research the spectral optical characteristics (diffuse spectral reflectance and transmittance) for a number of human teeth were measured in the 250 to 1500 nm region of the electromagnetic spectrum. From the reflectance and transmittance of the dental enamel the spectral absorptance and thus the attenuation coefficient can be determined. The optical characteristics of the human incisor/molar samples were measured with a Hitachi U3400 spectrophotometer and 60 mm (Phi) integrating sphere (IS) attachment, using a photomultiplier tube and PbS detectors. The characteristics of the IS attachment restricted the effective range of wavelengths that could be used to 250 - 1500 nm, which is also the wavelength range of interest. It is clear from the reflectance and transmittance characteristics of dental enamel that absorption is significantly higher in the UV and NIR regions than in the visible, with the attenuation coefficient the highest in the UV region from 250 to approximately 400 nm. The UV wavelengths may therefore prove to be extremely b