These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

UV-Visible Spectroscopy  

NSDL National Science Digital Library

This webpage, part of a larger project "Understanding Chemistry", provides an introduction to UV-visible spectroscopy suitable for use in introductory chemistry and introductory analytical chemistry courses. The pages discuss UV-visible light, absorption, Beer's law, the double-beam spectrometer, and introduce some standard applications of UV-vis spectroscopy.

Clark, Jim

2012-09-20

2

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

PubMed Central

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

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

2009-01-01

3

Development of a Fourier transform infrared spectroscopy coupled to UV-Visible analysis technique for aminosides and glycopeptides quantitation in antibiotic locks.  

PubMed

Antibiotic Lock technique maintains catheters' sterility in high-risk patients with long-term parenteral nutrition. In our institution, vancomycin, teicoplanin, amikacin and gentamicin locks are prepared in the pharmaceutical department. In order to insure patient safety and to comply to regulatory requirements, antibiotic locks are submitted to qualitative and quantitative assays prior to their release. The aim of this study was to develop an alternative quantitation technique for each of these 4 antibiotics, using a Fourier transform infrared (FTIR) coupled to UV-Visible spectroscopy and to compare results to HPLC or Immunochemistry assays. Prevalidation studies permitted to assess spectroscopic conditions used for antibiotic locks quantitation: FTIR/UV combinations were used for amikacin (1091-1115cm(-1) and 208-224nm), vancomycin (1222-1240cm(-1) and 276-280nm), and teicoplanin (1226-1230cm(-1) and 278-282nm). Gentamicin was quantified with FTIR only (1045-1169cm(-1) and 2715-2850cm(-1)) due to interferences in UV domain of parabens, preservatives present in the commercial brand used to prepare locks. For all AL, the method was linear (R(2)=0.996 to 0.999), accurate, repeatable (intraday RSD%: from 2.9 to 7.1% and inter-days RSD%: 2.9 to 5.1%) and precise. Compared to the reference methods, the FTIR/UV method appeared tightly correlated (Pearson factor: 97.4 to 99.9%) and did not show significant difference in recovery determinations. We developed a new simple reliable analysis technique for antibiotics quantitation in locks using an original association of FTIR and UV analysis, allowing a short time analysis to identify and quantify the studied antibiotics. PMID:24438668

Sayet, G; Sinegre, M; Ben Reguiga, M

2014-01-01

4

The use of UV-visible reflectance spectroscopy as an objective tool to evaluate pearl quality.  

PubMed

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

Agatonovic-Kustrin, Snezana; Morton, David W

2012-07-01

5

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

PubMed

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

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

2012-06-01

6

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. PMID:18927082

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

2008-01-01

7

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

8

Anisotropy in structural and physical properties in tetrathiafulvalene derivatives-based zone-cast layers as seen by Raman spectroscopy, UV-visible spectroscopy, and field effect measurements  

NASA Astrophysics Data System (ADS)

We have studied anisotropy of thin layers of amphiphilic tetrathiafulvalene derivatives (TTF-4SCn, with n=12, 18, and 22) obtained by zone-casting technique. All the films show optical anisotropy, as seen by polarized optical microscopy and polarized UV-visible spectroscopy. By using polarized Raman spectroscopy an angular dependence of intensity of different vibrational modes in respect to the zone-casting direction was determined. It was found that intensities of the modes related to central and ring C=C vibrations in the TTF core depend very strongly on the angle between the zone-cast direction and polarization plane of incident laser light. Comparison of the deduced orientation of the molecules in one of the films (TTF-4SC18) with its crystal structure shows that the polarized Raman spectroscopy can be useful for controlling orientation of molecules in thin films (e.g., for online monitoring). Organic field effect transistors (OFETs), with channels oriented in parallel and perpendicularly to the zone-casting direction, were built using the oriented TTF-4SCn films. In all cases a strong anisotropy of the charge carrier mobility (?) was found; the best results were obtained for OFETs with TTF-4SC18, for which ??=0.25 cm2/V s, ON/OFF>105, and ??/???170.

Kotarba, Sylwia; Jung, Jaroslaw; Kowalska, Aneta; Marszalek, Tomasz; Kozanecki, Marcin; Miskiewicz, Pawel; Mas-Torrent, Marta; Rovira, Concepció; Veciana, Jaume; Puigmarti-Luis, Josep; Ulanski, Jacek

2010-07-01

9

An experimental study of the structural and vibrational properties of sesquiterpene lactone cnicin using FT-IR, FT-Raman, UV-visible and NMR spectroscopies  

NASA Astrophysics Data System (ADS)

An experimental and theoretical investigation of cnicin is presented, combining the use of infrared, Raman, NMR and UV-visible spectroscopies with density functional theory (DFT) that employs hybrid B3LYP exchange correlation functional and a 6-31G? basis set. The molecular electrostatic potentials, atomic charges, bond orders, stabilization energies, topological properties and energy gap are presented by performing NBO, AIM and HOMO-LUMO calculations at the same level of theory as cnicin. A complete vibrational compound assignment was performed by employing internal coordinate analysis and a scaled quantum mechanical force field (SQMFF) methodology. Comparisons between the theoretical and experimental vibrational and ultraviolet-visible spectra show a strong concordance. The geometrical parameters and NBO studies suggest a probable negative Cotton effect for cnicin, which can be attributed to the ? ? ?? transition for an ?,?-unsaturated ?-lactone, as reported in the literature.

Chain, Fernando; Romano, Elida; Leyton, Patricio; Paipa, Carolina; Catalán, César Atilio Nazareno; Fortuna, Mario Antonio; Brandán, Silvia Antonia

2014-05-01

10

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

E-print Network

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

Bell, Alexis T.

11

Effect of pH on the chemical modification of quercetin and structurally related flavonoids characterized by optical (UV-visible and Raman) spectroscopy.  

PubMed

In this work we report the study of the chemical modifications undergone by flavonoids, especially by quercetin (QUC), under alkaline conditions by UV-visible absorption, Raman and surface-enhanced Raman scattering (SERS) spectroscopy, the study was performed in aqueous solution and also on Ag nanoparticles (AgNPs). Several processes are involved in the effect of alkaline pH both in solution and on AgNPs: autoxidation affecting mainly the C-ring of the molecule and giving rise to the molecular fragmentation leading to simpler molecular products, and/or the dimerization and further polymerization leading to species with a higher molecular weight. In addition, there exists a clear structure-instability correlation concerning mainly particular groups in the molecule: the C3-OH group in the C-ring, the catechol moiety in the B-ring and the C2=C3 bond also existing in the C-ring. QUC possesses all these groups and exhibits high instability in alkaline solution. The SERS spectra registered at different pH revealed a change in the dimerization protocol of QUC going from the A- and C-rings-like-condensation to B-ring-like-condensation. Increasing the knowledge of the chemical properties of these compounds and determining the structure-activity relationship under specific environmental factors allow us to improve their beneficial properties for health as well as the preservation of Cultural Heritage objects, for example, by preventing their degradation. PMID:24836778

Jurasekova, Z; Domingo, C; Garcia-Ramos, J V; Sanchez-Cortes, S

2014-07-01

12

The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy  

NASA Astrophysics Data System (ADS)

Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

Armendariz, Veronica; Parsons, Jason G.; Lopez, Martha L.; Peralta-Videa, Jose R.; Jose-Yacaman, Miguel; Gardea-Torresdey, Jorge L.

2009-03-01

13

Thermal behavior of J-aggregates in mixed Langmuir-Blodgett films composed of merocyanine dye and deuterated arachidic acid investigated by UV-visible and infrared absorption spectroscopy.  

PubMed

We have investigated the thermal behavior of J-aggregates in the mixed Langmuir-Blodgett (LB) films composed of the merocyanine dye (MS18)-deuterated arachidic acid (C20-d) binary system in the temperature range from 25 to 250 degrees C by means of UV-visible and IR transmission absorption spectroscopy. The temperature-dependent variations in both UV-visible and IR absorption spectra indicate that the MS18 aggregation states are linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of the MS18 hydrocarbon chain. The J-aggregate formed at 25 degrees C in the mixed LB films dissociates in the temperature range from 25 to 110 degrees C, which is mainly ascribed to the increase in the thermal mobility of MS18 hydrocarbon chain and the dissociation of the chelation by a cadmium ion to the MS18 keto group. A thermally induced blue-shifted band appears at around 515 nm from 110 to 160 degrees C. This band is attributed to oligomeric aggregation with side-by-side alignment of the MS18 transition dipole moments on the basis of the shift to a higher-energy side, broadening, and temporary increment of the MS18 intramolecular charge transfer of the band. Consequently, the appearance of the thermally induced blue-shifted band indicates the possibility that the MS18 aggregation states can be controlled from the red shift to the blue shift by the annealing method adopted in the present study. PMID:17530788

Hirano, Yoshiaki; Tateno, Shinsuke; Ozaki, Yukihiro

2007-06-19

14

Quantitative monitoring of an activated sludge reactor using on-line UV-visible and near-infrared spectroscopy  

Microsoft Academic Search

The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state\\u000a monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated\\u000a with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools\\u000a for bioprocess monitoring and control. Once implemented

Mafalda C. Sarraguça; Ana Paulo; Madalena M. Alves; Ana M. A. Dias; João A. Lopes; Eugénio C. Ferreira

2009-01-01

15

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

PubMed Central

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

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

2014-01-01

16

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

NASA Astrophysics Data System (ADS)

Carbonation of concrete by atmospheric CO 2 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 iron in 1M NaOH produced by sparging the electrolyte with a CO 2 + air mixture. Decreasing the pH from 8.02 to 7.69 produced the disappearance of the Fe 2O 3 PMR signal and nearly a doubling of the PMR maximum of FeOOH, pointing to a hydration of Fe 2O 3 to FeOOH preceding the breakdown of the passivating layer. A further decrease of only 0.07 pH units, down to pH 7.62, effected an increase of the corrosion rate of nearly two orders of magnitude and the disappearance of the PMR spectrum of the passivating layer, this being the first spectroscopic proof that depassivation by carbonation is due to a complete electrochemical dissolution of the passivating layer.

Climent, Miguel A.; Gutiérrez, Claudio

1995-06-01

17

Spectrophotometer, Scanning UV-Visible (ChemPages Lab)  

NSDL National Science Digital Library

Spectrophotometer, Scanning UV/Visible: this is a resource in the collection "ChemPages Laboratory Resources". A scanning ultraviolet/visible (UV/Vis) spectrophotometer operates on the same principles as a Spectronic 20?. They both can be used for qualitative and quantitative analysis. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.

18

UV–visible studies of nickel oxide thin film grown by thermal oxidation of nickel  

Microsoft Academic Search

In this work, we report an experimental study on optical properties of nickel oxide thin film by UV–visible spectroscopy. The nickel oxide thin film is grown by the oxidation of nickel deposited on ITO (tin doped indium oxide) coated glass substrate. The phase formation and electrical properties are studied with XRD and electrometer, respectively. On heat treatment at 500°C for

P. Mohanty; Chandana Rath; P. Mallick; R. Biswal; N. C. Mishra

2010-01-01

19

In situ UV-visible spectroelectrochemical studies on the copolymerization of diphenylamine with ortho-methoxy aniline.  

PubMed

UV-visible spectroelectrochemical studies on copolymerization of diphenylamine (DPA) with ortho-methoxy aniline (OMA) were carried out for different feed ratios of DPA and OMA using indium tin oxide (ITO)-coated glass as working electrode. The UV-visible spectra show clear dependencies on the molar feed composition of DPA or OMA used in electropolymerization. Derivative cyclic voltabsorptogram (DCVA) was deduced at the wavelengths corresponding to the absorption by the intermediate species and used to confirm the intermediates generated during the electropolymerization. The composition of DPA and OMA in the copolymer for the copolymers synthesized with different molar feed ratios of DPA and OMA was determined by UV-visible spectroscopy. Reactivity ratios of DPA and OMA were deduced by using Fineman-Ross and Kelen-Tudos methods and correlated with spectroelectrochemical results. PMID:12714067

Santhosh, P; Gopalan, A; Vasudevan, T

2003-05-01

20

Photocatalytic activity of Fe-doped CaTiO? under UV-visible light.  

PubMed

The photocatalytic degradation of methylene blue (MB) over Fe-doped CaTiO? under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) system, Fourier transform infrared spectra (FT-IR), and UV-visible diffuse reflectance spectroscopy (DRS). The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO? in the visible light region. The Fe-doped CaTiO? exhibited higher photocatalytic activity than CaTiO? for the degradation of MB. However, the photocatalytic activity of the Fe-doped CaTiO? was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO? prepared at 500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB (10ppm) under UV-visible light for 180 min. PMID:25079998

Yang, He; Han, Chong; Xue, Xiangxin

2014-07-01

21

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

PubMed

In this study 3,3',4,4'-tetrachloroazobenzene (TCAB) was prepared and then characterized by infrared, Raman, multidimensional nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopies. The density functional theory (DFT) together with the 6-31G(*) and 6-311++G(**) basis sets were used to study the structures and vibrational properties of the two cis and trans isomers of TCAB. The harmonic vibrational wavenumbers for the optimized geometries were calculated at the same theory levels. A complete assignment of all the observed bands in the vibrational spectra of TCAB was performed combining the DFT calculations with the scaled quantum mechanical force field (SQMFF) methodology. The molecular electrostatic potentials, atomic charges, bond orders and frontier orbitals for the two isomers of TCAB were compared and analyzed. The comparison of the theoretical ultraviolet-visible spectrum with the corresponding experimental demonstrates a good concordance while the calculated (1)H and (13)C chemicals shifts are in good conformity with the corresponding experimental NMR spectra of TCAB in solution. The npp(*) transitions for both forms were studied by natural bond orbital (NBO) while the topological properties were calculated by employing Bader's Atoms in the Molecules (AIM) theory. This study shows that the cis and trans isomers exhibit different structural and vibrational properties and absorption bands. PMID:25106816

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

2015-01-01

22

Versatile plasma display technology for UV-visible scene projector  

NASA Astrophysics Data System (ADS)

The results of testing two technologies based on gas microplasmas for the generation of UV-visible light is detailed. A microcavity device from the University of Illinois at Champaign-Urbana have been delivered with an Ar/D II gas mixture. Emission from the Ar/Ne as well as an Ar/D II eximer in the 250-400nm range, as well as argon lines in the visible and near infrared, are measured. Development of addressing arrays is discussed as is the potential of emission in other wavebands with other gas species. A 100x40 array of plasmaspheres combined with electronics capable of projecting images at 1000 Hz with 10 bits of grayscale resolution has been built and tested. This system, built by Imaging Systems Technology (IST), is capable of accepting DVI output from a HWIL system and projecting UV from a gas captured in the spheres. This array uses an argon neon gas mixture to produce UV, visible and near infrared light. Performance data discussed for both arrays include: maximum and minimum brightness, uniformity, spectral content, speed, linearity, crosstalk, resolution, and frame rate. Extensions of these technologies to larger arrays with wider spectral bandwidth for use in multispectral projectors are discussed.

Ginn, Robert; Solomon, Steven; Park, Sung-Jin; Eden, J. G.; Guy, Jeff; Peters, Ed

2007-04-01

23

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

24

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

25

Star-Pointing UV-Visible Spectrometer for Remote-Sensing of the Stratosphere.  

National Technical Information Service (NTIS)

We have constructed a novel instrument for ground-based remote sensing, by mounting a UV-visible spectrometer on a telescope and observing the absorption by atmospheric constituents of light from stars. Potentially, the instrument can observe stratospheri...

H. K. Roscoe, R. A. Freshwater, R. L. Jones, D. J. Fish, J. E. Harries

1994-01-01

26

Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer  

SciTech Connect

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

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

2007-04-23

27

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...

28

Quantitative tunneling spectroscopy of nanocrystals  

SciTech Connect

The proposed goals of this collaborative work were to systematically characterize the electronic structure and dynamics of 3-dimensional metal and semiconducting nanocrystals using scanning tunneling microscopy/spectroscopy (STM/STS) and ballistic electron emission spectroscopy (BEES). This report describes progress in the spectroscopic work and in the development of methods for creating and characterizing gold nanocrystals. During the grant period, substantial effort also was devoted to the development of epitaxial graphene (EG), a very promising materials system with outstanding potential for nanometer-scale ballistic and coherent devices ("graphene" refers to one atomic layer of graphitic, sp2 -bonded carbon atoms [or more loosely, few layers]). Funding from this DOE grant was critical for the initial development of epitaxial graphene for nanoelectronics

First, Phillip N; Whetten, Robert L; Schaaff, T Gregory

2007-05-25

29

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

30

A star-pointing UV-visible spectrometer for remote-sensing of the stratosphere  

NASA Technical Reports Server (NTRS)

We have constructed a novel instrument for ground-based remote sensing, by mounting a UV-visible spectrometer on a telescope and observing the absorption by atmospheric constituents of light from stars. Potentially, the instrument can observe stratospheric O3, NO3, NO2, and OClO.

Roscoe, Howard K.; Freshwater, Ray A.; Jones, Rod L.; Fish, Debbie J.; Harries, John E.; Wolfenden, Roger; Stone, Phillip

1994-01-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

32

UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.  

PubMed

Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency. PMID:24217967

Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

2014-10-01

33

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

34

Application of infrared and UV-visible remote sensing techniques for studying the stratosphere and for estimating anthrophogenic emissions  

NASA Astrophysics Data System (ADS)

Infrared and UV/visible broadband absorption techniques have been used in three applications related to environmental research and atmospheric science. The techniques are based on measuring the attenuation of light by the atmosphere in the infrared and UV/visible region, and since a very large number of species absorb light in these wavelength regions, the techniques studied allow the measurement of several species simultaneously. Measurements of high resolution infrared solar spectra have been conducted during 1995 to 1998 at an observatory in Norway (60.2oN, 10.75oE). From the solar spectra, atmospheric columns of O/sb 3 and the most abundant nitrogen, chlorine and fluorine species in the stratosphere have been retrieved, such as: HCl, ClONO/sb 2, ClO, HNO/sb 3, N/sb 2O, HF and COF/sb 2. In addition, height concentration profiles of HCl, O/sb 3, HF, N/sb 2O and CH/sb 4 have been retrieved from the spectra. These were compared to several other techniques, indicating uncertainties of 10-20% at 20 km decreasing both upwards and downwards in altitude. Chlorine activation, i.e. conversion of the reservoir species HCl and ClONO/sb 2 to ClO on ice particles in the stratosphere, could be quantified on several occasions during the measurement period. The measurements also indicated significant ozone depletion in the Arctic polar stratosphere of 1995. In the second application a new method for quantitative estimation of fugitive emissions of hydrocarbons from petrochemical industries has been developed. Tracer gases are released on the location of the leakages, and then concentration measurements are conducted downwind, over a long atmospheric path, by infrared absorption technique. What is unique with the method is a new approach based on the correlation of the tracer and the source gas concentrations over time. The method has been used to measure diffuse emissions of ethylene and propylene at several industrial sites during 1994 to 1998. Sensitivity experiments and comparison with other techniques indicate the possibility of 20% accuracy for flux measurements of volume and area sources with variable strengths 5-30 kg/h. The third application studied concerns the development of a method for in situ measurements of environmental pollutants (NO, NO/sb 2, SO/sb 2 and NH/sb 3) in flue gases by UV/visible absorption technique. The temperatures can be very high in the flue gases and, since the absorption line strengths are sensitive to the temperature, errors of up to 70% at 700K can be obtained if not taken into account. A laboratory study was conducted on this issue together with modeling of NO spectra. The concentrations of pollutants can be very high in flue gases why the absorption becomes nonlinear and yields errors of up to 30%. This has been studied in laboratory studies and modeling of NO spectra. The results from the laboratory studies were applied to compensate for the temperature and nonlinearity effects in real measurements.

Mellqvist, Johan Magnus

1999-11-01

35

Intercalation and groove binding of an acridine spermine conjugate on DNA sequences: an FT Raman and UV visible absorption study  

NASA Astrophysics Data System (ADS)

Acridine and acridine derivatives are known as powerful DNA intercalators. Interactions of the acridine-spermine conjugate N1-(Acridin-9-yl)-1,5,9,14,18-pentaazaoctadecane on two 16-mer oligonucleotides containing either alternating guanine-cytosine or adenine-thymine sequences were studied by optical spectroscopies. UV-visible absorption spectra of oligonucleotide/conjugate solutions at different molar ratios were recorded. The conjugate bands in the 350-500 nm region showed strong hypochromism and slight red shift in the presence of the oligonucleotides, thus indicating that the acridine moieties intercalate into adjacent base pairs of the oligonucleotides. These effects stopped near the 1:1 molar ratio, indicating that each oligonucleotide chain can only host one conjugate molecule. Raman spectra of solutions 60 mM (in phosphate) of the oligonucleotides and 3 mM of the conjugate were also recorded. Upon intercalation, the spectra showed relevant wavenumber shifts for skeletal and base vibrations, which have been largely attributed to the interactions of the positively charged side chain groups with the reactive sites of the base residues. Raman data suggested the existence of sequence selectivity induced by the spermine tail. Intercalation together to spermine interaction by the major groove was favoured for the guanine-cytosine sequence, while no groove preference was achieved for the adenine-thymine sequence.

Pérez-Flores, L.; Ruiz-Chica, A. J.; Delcros, J. G.; Sánchez-Jiménez, F.; Ramírez, F. J.

2005-06-01

36

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

PubMed

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

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

2014-10-15

37

UV, visible, and near-IR reflectivity data for magnetic soils/rocks from Brazil  

NASA Technical Reports Server (NTRS)

The objective is to obtain UV, visible, and near-IR reflectivity spectra for several magnetic Brazilian soils/rocks and compare them to corresponding data for Mars to see if these materials satisfy both magnetic and spectral constraints for Mars. Selected physical properties of the magnetic Brazilian soils/rocks are presented. In general, the spectral features resulting from ferric crystal-field transitions are much better defined in the spectra of the magnetic Brazilian soils/rocks than in Martian spectral data. Presumably, this results from a relatively higher proportion of crystalline ferric oxides for the former. The apparent masking of the spectral signature of maghemite by hematite or goethite for the Brazilian samples implies the magnetic and spectral constraints for Mars can be decoupled. That is, maghemite may be present in magnetically-significant but optically-insignificant amounts compared to crystalline hematite.

Vempati, R. K.; Morris, R. V.; Lauer, H. V., Jr.; Coey, J. M. D.

1991-01-01

38

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

39

Spectroscopy of fullerenes, fulleranes and PAHs in the UV, visible and near infrared spectral range  

E-print Network

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

Cataldo, F; Manchado, A; Iglesias-Groth, S

2013-01-01

40

PSC and volcanic aerosol routine observations in Antarctica by UV-visible ground-based spectrometry  

NASA Technical Reports Server (NTRS)

Polar statospheric clouds (PSC) and stratospheric aerosol can be observed by ground-based UV-visible spectrometry by looking at the variation of the color of the sky during twilight. A radiative transfer model shows that reddenings are caused by high altitude (22-28 km) thin layers of scatterers, while low altitude (12-20 km) thick ones result in blueings. The color index method applied on 4 years of observations at Dumont d'Urville (67 deg S), from 1988 to 1991, shows that probably because the station is located at the edge of the vortex, dense PSC are uncommon. More unexpected is the existence of a systematic seasonal variation of the color of the twilight sky - bluer at spring - which reveals the formation of a dense scattering layer at or just above the tropopause at the end of the winter. Large scattering layers are reported above the station in 1991, first in August around 12-14 km, later in September at 22-24 km. They are attributed to volcanic aerosol from Mt Hudson and Mt Pinatubo respectively, which erupted in 1991. Inspection of the data shows that the lowest entered rapidly into the polar vortex but not the highest which remained outside, demonstrating that the vortex was isolated at 22-26 km.

Sarkissian, A.; Pommereau, J. P.; Goutail, F.

1994-01-01

41

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

43

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

NASA Technical Reports Server (NTRS)

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

Mitchell, B. Greg

2000-01-01

44

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

SciTech Connect

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-{mu}m diameter. These oxidations were examined with respect to the site of electron transfer and to the fate of the NO group on the time scales of thin-layer cyclic voltammetry and bulk controlled-potential electrolysis. The NO group remains coordinated to the Fe(III) center after electrooxidation of (P)Fe(NO) and a 166-187-cm{sup {minus}1} shift in NO vibration is observed upon going from (P)Fe(NO) to ((P)Fe(NO)){sup +} in CH{sub 2}Cl{sub 2}, 0.1 M TMAP. However, the bound NO ligand dissociates from ((P)Fe(NO)){sup 2+}, which is electrogenerated at more positive potentials. The effects of bound halide ion or neutral ligand coordination on {gamma}{sub NO} of ((P)Fe(NO)){sup +} were also examined. {gamma}{sub NO} of (P)Fe(NO)X, where X = Cl{sup {minus}}, Br{sup {minus}}, or I{sup {minus}}, is linearly related to the ionization potential of HX while {gamma}{sub NO} of ((P)Fe(NO)(S)){sup +} (where S is a bound solvent molecule) is linearly correlated with the Gutmann solvent number (DN) of the trans-lighted solvent molecule in bulk CH{sub 2}Cl{sub 2}.

Mu, X.H.; Kadish, K.M. (Univ. of Houston, TX (USA))

1988-12-28

45

Intrinsic Raman spectroscopy for quantitative biological spectroscopy Part II  

PubMed Central

We demonstrate the effectiveness of intrinsic Raman spectroscopy (IRS) at reducing errors caused by absorption and scattering. Physical tissue models, solutions of varying absorption and scattering coefficients with known concentrations of Raman scatterers, are studied. We show significant improvement in prediction error by implementing IRS to predict concentrations of Raman scatterers using both ordinary least squares regression (OLS) and partial least squares regression (PLS). In particular, we show that IRS provides a robust calibration model that does not increase in error when applied to samples with optical properties outside the range of calibration. PMID:18711512

Bechtel, Kate L.; Shih, Wei-Chuan; Feld, Michael S.

2009-01-01

46

Journal of Quantitative Spectroscopy & Radiative Transfer 101 (2006) 488497  

E-print Network

and by reflecting and absorbing incoming short-wave solar radiation. However, cirrus clouds remain a significantJournal of Quantitative Spectroscopy & Radiative Transfer 101 (2006) 488­497 Modeling single thickness, the influence of particle shape on the radiative forcing caused by a cloud composed of small ice

47

Journal of Quantitative Spectroscopy & Radiative Transfer 101 (2006) 404410  

E-print Network

a well-collimated detector of electromagnetic radiation located at a distance r from the scatteringJournal of Quantitative Spectroscopy & Radiative Transfer 101 (2006) 404­410 The electromagnetic, New York, NY 10025, USA Abstract We revisit the optical theorem relevant to the far-field

48

Features of the Quantitative Analysis in Moessbauer Spectroscopy  

SciTech Connect

The results describing the effect of different factors on errors in quantitative determination of the phase composition of studied substances by Moessbauer spectroscopy absorption are presented, and the ways of using them are suggested. The effectiveness of the suggested methods is verified by an example of analyzing standard and unknown compositions.

Semenov, V. G.; Panchuk, V. V. [St. Petersburg State University, St. Petersburg (Russian Federation); Irkaev, S. M. [Institute for Analytical Instrumentation RAS, St. Petersburg (Russian Federation)

2010-07-13

49

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

NASA Astrophysics Data System (ADS)

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

Shukla, Madhulata; Srivastava, Nitin; Saha, Satyen

2012-08-01

50

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

51

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. PMID:22195026

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

52

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

53

Quantitative polarized Raman spectroscopy in highly turbid bone tissue  

PubMed Central

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. PMID:20615030

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

2010-01-01

54

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

55

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

56

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

2011-07-01

57

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. PMID:21160072

2010-01-01

58

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

59

Quantitative Cherenkov emission spectroscopy for tissue oxygenation assessment  

PubMed Central

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

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

2012-01-01

60

Determination of the overlapping pKa values of resorcinol using UV-visible spectroscopy and DFT methods.  

PubMed

In this paper we determine the overlapping pK(a) values of resorcinol in water, applying a UV-Vis spectroscopic method that uses absorbance diagrams. On the other hand, in order to explain the pK(a) values obtained, we also investigate the molecular conformations and solute-solvent interactions of the resorcinate anions, using ab initio and density functional theory methods. Several ionization reactions and equilibria in protic solvents, which possess a high hydrogen-bond-donor capability, are proposed. The mentioned reactions and equilibria constituted the indispensable theoretical basis to calculate the acidity constants of resorcinol. Basis sets at the HF/6-31 + G(d) and B3LYP/6-31 + G(d) levels of theory were used for calculations. Tomasi's method was used to analyze the formation of intermolecular hydrogen bonds between the resorcinate anions and water molecules. In this way, it was determined that in alkaline aqueous solutions the monoanion and dianion of resorcinol are solvated with two and four molecules of water, respectively. The agreement between the experimentally determined pK(a) values and those reported in the literature demonstrates the applicability and accurateness of the spectroscopic method here used. On the other hand, the agreement between the experimental and theoretically calculated pK(a) values provides solid support for the acid-base reactions proposed in this work. PMID:15556426

Blanco, S E; Almandoz, M C; Ferretti, F H

2005-01-01

61

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

E-print Network

Absolute Quantitation of Bacterial Biofilm Adhesion and Viscoelasticity by Microbead Force in biofilms. By performing microbead force spectroscopy with a closed-loop atomic force microscope, we developed standardized conditions for microbead force spectroscopy to enable meaningful comparison of data

Dutcher, John

62

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

NASA Astrophysics Data System (ADS)

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

Purcell, Dale Kevin

63

Quantitative analysis of ceramics by laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

A quantitative elemental analysis of ceramics was carried out with laser-induced breakdown spectroscopy. A Q-switched Nd:YAG laser was focused on ceramic targets in an argon atmosphere at reduced pressure, and the emission spectra from laser-induced plasma were measured using time-resolved spectroscopy. The experimental results showed that in argon at approximately 200 Torr, the spectral line intensity and the line-to-background ratio were maximized by observing the laser plasma with a time delay of 0.4 ?s. Also, time-resolved measurement of a spectrum in the initial stage of plasma generation (˜1 ?s) was effective for improving the slope of the calibration curve. Based on the results, standard ceramic samples were analyzed for magnesium, aluminum, calcium, iron and titanium, and linear calibration curves with a slope of unity were obtained by measuring spectra with a gate width of 0.4 ?s at a delay time of 0.4 ?s after the laser pulse in argon at 200 Torr.

Kuzuya, M.; Murakami, M.; Maruyama, N.

2003-05-01

64

Quantitative investigation of two metallohydrolases by X-ray absorption spectroscopy near-edge spectroscopy  

NASA Astrophysics Data System (ADS)

The last several years have witnessed a tremendous increase in biological applications using X-ray absorption spectroscopy (BioXAS), thanks to continuous advancements in synchrotron radiation (SR) sources and detector technology. However, XAS applications in many biological systems have been limited by the intrinsic limitations of the Extended X-ray Absorption Fine Structure (EXAFS) technique e.g., the lack of sensitivity to bond angles. As a consequence, the application of the X-ray absorption near-edge structure (XANES) spectroscopy changed this scenario that is now continuously changing with the introduction of the first quantitative XANES packages such as Minut XANES (MXAN). Here we present and discuss the XANES code MXAN, a novel XANES-fitting package that allows a quantitative analysis of experimental data applied to Zn K-edge spectra of two metalloproteins: Leptospira interrogans Peptide deformylase ( LiPDF) and acutolysin-C, a representative of snake venom metalloproteinases (SVMPs) from Agkistrodon acutus venom. The analysis on these two metallohydrolases reveals that proteolytic activities are correlated to subtle conformation changes around the zinc ion. In particular, this quantitative study clarifies the occurrence of the LiPDF catalytic mechanism via a two-water-molecules model, whereas in the acutolysin-C we have observed a different proteolytic activity correlated to structural changes around the zinc ion induced by pH variations.

Zhao, W.; Chu, W. S.; Yang, F. F.; Yu, M. J.; Chen, D. L.; Guo, X. Y.; Zhou, D. W.; Shi, N.; Marcelli, A.; Niu, L. W.; Teng, M. K.; Gong, W. M.; Benfatto, M.; Wu, Z. Y.

2007-09-01

65

Optical characterization of materials desposited by different processes: the LaF3 in the UV-visible region  

NASA Astrophysics Data System (ADS)

The optical characterization of materials in thin film phase is a standard task in the field of coating technology. There are experimental circumstances where the accurate comparison between several deposition processes (for the same material) is important. In these cases, several sets of substrates are coated at the different deposition plants. The samples will be subsequently analyzed using, if the plants are at different locations, different spectrophometers and finally the results of all the optical characterizations will be compared. The aim of this work is to present the results of a global procedure for the optical characterization of LaF3 in the UV-visible region, deposited at three different plants. We have used R and T spectrophotometric data and we have assumed the following model for the optical characterization: n(?)=n0+n1/?2, k(?)=k0 exp(k1/(?). Our method characterizes all the samples from the same deposition process by a single set of parameters (instead of a set for each sample), using all the available measurements to determine them in a single numerical fitting, without a significant loss in the quality of the fittins. This procedure reduces the number of parameters and makes the comparison between different deposition processes more clear. By using similar results obtained for MgF2 the optical characterization of stacks (manufactured using MgF2 and LaF3) is also presented.

Bosch, Salvador; Leinfellner, Norbert; Quesnel, Etienne; Duparre, Angela; Ferre-Borrull, Josep; Guenster, Stefan; Ristau, Detlev

2000-10-01

66

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

67

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

68

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

E-print Network

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

Torgersen, Christian

69

ZnO(N)-Spiro-MeOTAD hybrid photodiode: an efficient self-powered fast-response UV (visible) photosensor  

NASA Astrophysics Data System (ADS)

Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with environmentally friendly and earth-abundant materials. Herein, we report a facile solution-processed fabrication of a self-powered organic-inorganic hybrid photodetector using n-type oriented ZnO nanorods and p-type Spiro-MeOTAD semiconductor. ZnO is eco-friendly and earth-abundant, and Spiro-MeOTAD is non-hazardous. We show that the latter has far less toxicity than the toxic elements stated above. This visible blind UV photodetector shows high sensitivity (102) and a UV/visible rejection ratio of 300. It also exhibits fast response times of ?rise ~ 200 ?s and ?fall ~ 950 ?s. Importantly, with a small modification of nitrogen incorporation in ZnO one can also realize a highly-sensitive self-powered visible light photodetector with at least 1000% (or higher) improvements in quality factors (photocurrent/sensitivity/response time) as compared to previously reported organic-inorganic hybrid photo-detectors based on metal-chalcogenides (CdS-PANI or CuInSe2-P3HT). Interestingly, the broadband sensitivity of such N:ZnO-Spiro-MeOTAD photodiode enables sensing of low intensity (~28 ?W cm-2) ambient white light with a high photocurrent density of 120 nA cm-2 making it an efficient ambient white light detector.Organic-inorganic hybrid photo-detectors with a self-sufficient mode of operation represent a research area of great current interest. In most efficient photodetectors and optoelectronic devices compound semiconductors containing toxic elements such as Cd, As, Te, S, Se etc. are used and these are also expensive. Hence there is also a rapidly growing interest in replacing these with environmentally friendly and earth-abundant materials. Herein, we report a facile solution-processed fabrication of a self-powered organic-inorganic hybrid photodetector using n-type oriented ZnO nanorods and p-type Spiro-MeOTAD semiconductor. ZnO is eco-friendly and earth-abundant, and Spiro-MeOTAD is non-hazardous. We show that the latter has far less toxicity than the toxic elements stated above. This visible blind UV photodetector shows high sensitivity (102) and a UV/visible rejection ratio of 300. It also exhibits fast response times of ?rise ~ 200 ?s and ?fall ~ 950 ?s. Importantly, with a small modification of nitrogen incorporation in ZnO one can also realize a highly-sensitive self-powered visible light photodetector with at least 1000% (or higher) improvements in quality factors (photocurrent/sensitivity/response time) as compared to previously reported organic-inorganic hybrid photo-detectors based on metal-chalcogenides (CdS-PANI or CuInSe2-P3HT). Interestingly, the broadband sensitivity of such N:ZnO-Spiro-MeOTAD photodiode enables sensing of low intensity (~28 ?W cm-2) ambient white light with a high photocurrent density of 120 nA cm-2 making it an efficient ambient white light detector. Electronic supplementary information (ESI) available: SI-1: response time measurements of self powered hybrid ZnO-SPD under nanosecond pulsed UV laser, SI-2: Raman analysis of N:ZnO and ZnO SI-3: cytotoxicity study on Spiro-MeOTAD SI-4: electrochemical Mott-Schottky plots of ZnO and N:ZnO. See DOI: 10.1039/c3nr04727j

Game, Onkar; Singh, Upendra; Kumari, Tanya; Banpurkar, Arun; Ogale, Satishchandra

2013-12-01

70

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

Microsoft Academic Search

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

Petros A. Tarantilis; George Tsoupras; Moschos Polissiou

1995-01-01

71

Coherent two-dimensional infrared spectroscopy: Quantitative analysis of protein secondary structure in solution  

E-print Network

We present a method to quantitatively determine the secondary structure composition of globular proteins using coherent two-dimensional infrared (2DIR) spectroscopy of backbone amide I vibrations (1550–1720 cm?1). Sixteen ...

Baiz, Carlos

72

Ultrafast two-photon absorption in organic molecules| Quantitative spectroscopy and applications.  

E-print Network

?? This dissertation explores quantitative two-photon absorption spectroscopy to relate molecular structure with optical properties of organic chromophores. The dissertation describes an advanced fluorescence-based technique… (more)

Makarov, Nikolay Sergeevich

2010-01-01

73

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

74

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

75

Quantitative biological Raman spectroscopy for non-invasive blood analysis  

E-print Network

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

Shih, Wei-Chuan

2007-01-01

76

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

E-print Network

Quantitative analysis of sulfur functional groups in natural organic matter by XANES spectroscopy sulfur functionalities in natural organic matter from S K-edge XANES spectroscopy are presented-induced errors, inherent to the choice of a particular curve, are typically lower than 5% of total sulfur

77

Quantitative characterization of catalyst layer degradation in PEM fuel cells by X-ray photoelectron spectroscopy  

Microsoft Academic Search

A quantitative analysis of catalyst layer degradation was performed with X-ray photoelectron spectroscopy (XPS). XPS is quantitative, surface-sensitive, and is able to distinguish different bonding environments or chemical states of fuel cell catalyst layers and polymer electrolyte membrane. These capabilities have allowed us to explore the complex mechanisms of degradation during fuel cell operation. The elemental surface concentrations of carbon,

Feng-Yuan Zhang; Suresh G. Advani; Ajay K. Prasad; Mary E. Boggs; Shawn P. Sullivan; Thomas P. Beebe Jr.

2009-01-01

78

Identification and Quantitative Determination of Dipropylene Glycol in Terpene Mixtures Using 13C NMR Spectroscopy  

Microsoft Academic Search

A method that allows direct identification and quantitative determination of dipropylene glycol (DPG) using C NMR spectroscopy was developed. The quantitative procedure was checked and validated with commercially available DPG, controlled with two DPG-added essential oils, and then applied to commercial “Extraits de parfum” (perfume extracts).

Josephine Ottavioli; Joseph Casanova; Ange Bighelli

2011-01-01

79

Gas-Phase Database for Quantitative Infrared Spectroscopy  

Microsoft Academic Search

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 0.1 cm¹ was selected to avoid degrading sharp spectral features, while also realizing that

Steven W. Sharpe; Timothy J. Johnson; Robert L. Sams; Pamela M. Chu; George C. Rhoderick; Patricia A. Johnson

2004-01-01

80

Quantitative determination of cephalexin in cephradine by NMR spectroscopy.  

PubMed

An NMR method to determine quantitatively the presence of cephalexin in cephradine was developed. The method is applicable to the chemical itself as well as to capsules and oral suspension formulations. The determination is based on the NMR signal arising from the five aromatic protons of the cephalexin molecule. Integration of this signal relative to a signal from cephradine provides the data necessary to determine the percentage of cephalexin present. The precision at the 2% cephalexin levels is +/- 0.18%. The time required to carry out a single analysis is about 10 min, and five analyses can be done in about 0.5 hr. PMID:702311

Warren, R J; Zarembo, J E; Staiger, D B; Post, A

1978-10-01

81

Quantitative Remote Laser-Induced Breakdown Spectroscopy by Multivariate Analysis  

NASA Astrophysics Data System (ADS)

The ChemCam instrument selected for the Mars Science Laboratory (MSL) rover includes a remote Laser- Induced Breakdown Spectrometer (LIBS) that will quantitatively probe samples up to 9m from the rover mast. LIBS is fundamentally an elemental analysis technique. LIBS involves focusing a Nd:YAG laser operating at 1064 nm onto the surface of the sample. The laser ablates material from the surface, generating an expanding plasma containing electronically excited ions, atoms, and small molecules. As these electronically excited species relax back to the ground state, they emit light at wavelengths characteristic of the species present in the sample. Some of this emission is directed into one of three dispersive spectrometers. In this paper, we studied a suite of 18 igneous and highly-metamorphosed samples from a wide variety of parageneses for which chemical analyses by XRF were already available. Rocks were chosen to represent a range of chemical composition from basalt to rhyolite, thus providing significant variations in all of the major element contents (Si, Fe, Al, Ca, Na, K, O, Ti, Mg, and Mn). These samples were probed at a 9m standoff distance under experimental conditions that are similar to ChemCam. Extracting quantitative elemental concentrations from LIBS spectra is complicated by the chemical matrix effects. Conventional methods for obtaining quantitative chemical data from LIBS analyses are compared with new multivariate analysis (MVA) techniques that appear to compensate for these chemical matrix effects. The traditional analyses use specific elemental peak heights or areas, which compared with calibration curves for each element at one or more emission lines for a series of standard samples. Because of matrix effects, the calibration standards generally must have similar chemistries to the unknown samples, and thus this conventional approach imposes severe limitations on application of the technique to remote analyses. In this suite of samples, the use of traditional methods results in chemical analyses with significant uncertainties. Alternatively, greatly-improved quantitative elemental analysis was accomplished by using a Partial Least Squares (PLS) calibration model for all of the major elements of interest. Principal Components Analysis (PCA) and Soft Independent Modeling of Class Analogy (SIMCA) are then employed to predict the rock-type of the sample. These MVA techniques appear to compensate for these matrix effects because the analysis finds correlations between the spectra (independent variables), the individual elements of interest (dependent variables such as Si) as well as the other elements in the matrix.

Clegg, S. M.; Sklute, E. C.; Dyar, M. D.; Barefield, J. E.; Wiens, R. C.

2007-12-01

82

Machine learning methods for quantitative analysis of Raman spectroscopy data  

NASA Astrophysics Data System (ADS)

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

Madden, Michael G.; Ryder, Alan G.

2003-03-01

83

Quantitative Raman spectroscopy for the analysis of carrot bioactives.  

PubMed

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

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

2013-03-20

84

Quantitative multiplex CARS spectroscopy in congested spectral regions  

NASA Astrophysics Data System (ADS)

A novel procedure is developed to describe and reproduce experimental coherent anti-Stokes Raman scattering (CARS) data, with particular emphasis on highly congested spectral regions. The approach - exemplified here with high-quality multiplex CARS data - makes use the maximum entropy method for phase retrieval. The retrieved imaginary part of the nonlinear susceptibility is shown to be equal to the spontaneous Raman spectrum. The phase retrieval procedure does not influence the noise contained in the spectra. The conversion of CARS to Raman data permits a quantitative interpretation of CARS spectra. This novel approach is demonstrated for highly congested multiplex CARS spectra of sucrose, fructose and glucose. This novel procedures enables extraction of vibrational information from multiplex CARS data without the use of a priori information of the sample.

Müller, Michiel; Rinia, Hilde A.; Bonn, Mischa; Vartiainen, Erik M.; Lisker, Melanie; van Bel, Aart

2007-02-01

85

Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves  

NASA Astrophysics Data System (ADS)

Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas, 21%-50%-100%, in five calves (group A) gave an increasing oxygen saturation of 19+/-4%, 24+/-5%, and 28+/-8% (p<0.001, ANOVA repeated measures design) and mean tissue fractions of 1.6% (cytochrome aa3) and 1.1% (hemo- and myoglobin). Cardiac arrest in two calves gave an oxygen saturation lower than 5%. In two calves (group B), a left ventricular assistive device (LVAD pump) was implanted. Oxygen saturation in group B animals increased with LVAD pump speed (p<0.001, ANOVA) and with oxygen content in inhaled gas (p<0.001, ANOVA). The cytochrome aa3 oxidation level was above 96% in both group A and group B calves, including the two cases involving cardiac arrest. In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations were in agreement with previously presented results, demonstrating the potential of the method.

Lindbergh, Tobias; Larsson, Marcus; Szabó, Zoltán; Casimir-Ahn, Henrik; Strömberg, Tomas

2010-03-01

86

Power-scalable tunable UV, visible, and NIR generation from an ultrafast fiber OPA based on four wave mixing in PCF  

NASA Astrophysics Data System (ADS)

An ultrafast fiber MOPA was developed which delivered high average power and rapid and continuous tunability over the range 1035 - 1070 nm. Through FWM in a single PCF, this source generated greater than 30% conversion efficiency to a narrow linewidth signal with tunability from 720 to 880 nm and a corresponding idler tunable from 1370 to 1880 nm. Generation of tunable signal SHG, signal-pump SFG, pump SHG and pump-idler SFG were demonstrated in a single angle tuned BBO crystal. The combined system enabled tunability over large portions of the UV, visible and NIR spectral range from 370 - 1900 nm with a very simple setup. There is scope for power scaling of the source and extending the wavelength coverage.

Yarrow, Michael J.; Wadsworth, William J.; Lavoute, Laure; Clowes, John R.; Grudinin, Anatoly B.

2012-02-01

87

Quantitative analysis of water-soluble vitamins by ATR-FTIR spectroscopy  

Microsoft Academic Search

HPLC and microbiology are the methods traditionally employed to control the vitamin content in food mixtures. However, considerations of cost, time of analysis per sample and complexities involved in the technique have hampered the acceptance of those methods for raw materials analysis. Fourier Transform Infrared (FTIR) spectroscopy has substantial potential as a quantitative quality control tool for the food industry.

C. Wojciechowski; N. Dupuy; C. D. Ta; J. P. Huvenne; P. Legrand

1998-01-01

88

Quantitative analysis of urinary stone composition with micro-Raman spectroscopy  

Microsoft Academic Search

Urolithiasis is a common, disturbing disease with high recurrent rate (60% in five years). Accurate identification of urinary stone composition is important for treatment and prevention purpose. Our previous studies have demonstrated that micro-Raman spectroscopy (MRS)-based approach successfully detects the composition of tiny stone powders after minimal invasive urological surgery. But quantitative analysis of urinary stones was not established yet.

Yi-Yu Huang; Yi-Chun Chiu; Huihua Kenny Chiang; Y. H. Jet Chou; Shing-Hwa Lu; Allen W. Chiu

2010-01-01

89

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

90

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

PubMed Central

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

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

2011-01-01

91

UV-visible and infrared absorption spectroscopic studies of gamma irradiated tungsten-doped lithium phosphate glasses  

NASA Astrophysics Data System (ADS)

Ultraviolet-visible and infrared spectroscopic techniques were employed to investigate the undoped lithium phosphate glass and other samples of the same composition doped with varying WO3 contents. The same spectroscopic properties were remeasured after subjecting the samples to 3 and 6 Mrad doses of gamma irradiation on the measured properties. Such combined analytical techniques are expected to give information about the state of tungsten ions in such lithium phosphate glass and justify the effect of gamma irradiation. The work aims to deduce the radiation-induced defects generated through successive gamma irradiation by optical measurements. Also, the study is expected to realize through IR spectroscopy, the main structural building groups and the influence of tungsten ions within the structural vibrational groups of the studied glasses.

ElBatal, F. H.; Ouis, M. A.

2011-11-01

92

[Quantitative analysis model of multi-component complex oil spill source based on near infrared spectroscopy].  

PubMed

Near infrared spectroscopy technology was used for quantitative analysis of the simulation of complex oil spill source. Three light petroleum products, i. e. gasoline, diesel fuel and kerosene oil, were selected and configured as simulated mixture of oil spill samples in accordance with different concentrations proportion, and their near infrared spectroscopy in the range of 8 000 -12 000 cm(-1) was collected by Fourier transform near infrared spectrometer. After processing the NIR spectra with different pretreatment methods, partial least squares method was used to establish quantitative analysis model for the mixture of oil spill samples. For gasoline, diesel fuel and kerosene oil, the second derivative method is the optimal pretreatment method, and for these three oil components in the ranges of 8 501.3-7 999.8 and 6 102.1-4 597.8 cm(-1); 6 549.5-4 597.8; 7 999.8-7 498.4 and 102.1-4 597.8 cm(-1), the correlation coefficients R2 of the prediction model are 0.998 2, 0.990 2 and 0.993 6 respectively, while the forecast RMSEP indicators are 0.474 7, 0.936 1 and 1.013 1 respectively; The experimental results show that using near infrared spectroscopy can quantitatively determine the content of each component in the simulated mixed oil spill samples, thus this method can provide effective means for the quantitative detection and analysis of complex marine oil spill source. PMID:23427535

Tan, Ai-Ling; Bi, Wei-Hong

2012-12-01

93

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

NASA Astrophysics Data System (ADS)

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

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

1994-09-01

94

Quantitative multivoxel 1 H MR spectroscopy of the brain in children with acute liver failure  

Microsoft Academic Search

Acute liver failure (ALF)-related encephalopathy was previously characterized by MR spectroscopy of single voxels containing\\u000a both grey and white matter brain tissue. Quantitative multivoxel MRS was used here to compare grey and white matter brain\\u000a tissue concentrations of glutamate\\/glutamine (Glx) and lactate in ALF and associate the results with other liver function\\u000a parameters. Five pediatric patients with ALF-related encephalopathy and

Paul E. Sijens; Heyder Alkefaji; Roelineke J. Lunsing; Francjan J. van Spronsen; Linda C. Meiners; Matthijs Oudkerk; Henkjan J. Verkade

2008-01-01

95

Qualitative and Quantitative Detection of Pesticides With Terahertz Time-Domain Spectroscopy  

Microsoft Academic Search

This paper used the newly developed terahertz time-domain spectroscopy (THz-TDS) to detect pesticides, especially imidacloprid, qualitatively and quantitatively in the frequency range of 0.5-1.6 THz. All together, four pesticides and three food powders, as well as polyethylene, were investigated. Different weight ratios of imidacloprid in polyethylene and in sticky rice powder were detected and analyzed with the partial least squares

Yuefang Hua; Hongjian Zhang

2010-01-01

96

Screening hypochromism (sieve effect) in red blood cells: a quantitative analysis  

PubMed Central

Multiwavelength UV-visible spectroscopy, Kramers-Kronig analysis, and several other experimental and theoretical tools have been applied over the last several decades to fathom absorption and scattering of light by suspensions of micron-sized pigmented particles, including red blood cells, but a satisfactory quantitative analysis of the difference between the absorption spectra of suspension of intact and lysed red blood cells is still lacking. It is stressed that such a comparison is meaningful only if the pertinent spectra are free from, or have been corrected for, scattering losses, and it is shown that Duysens’ theory can, whereas that of Vekshin cannot, account satisfactorily for the observed hypochromism of suspensions of red blood cells. PMID:24761307

Razi Naqvi, K.

2014-01-01

97

[Quantitative analysis of two-component polymer blends (PEG/PE) by infrared spectroscopy].  

PubMed

The concentration of the camponent of PEG/PE blends was analyzed quantitatively by infrared spectroscopy. The absorption peak area ratio of the selected mixture peaks used as the calibrating basis for the quantitative analysis was more reasonable than the peak area ratio of the pure peaks. The theoretical equation deducted by Beer-Lamber law was used to establish the working curve to calculate the composition of the responding functional groups in the film of the PEG/PE blends. The characteristic peaks of the crystal can not be selected as the calibrating basis for the quantitative measurement, because the crystallization has a great effect on the intensity of the absorption peaks. PMID:16827348

Wu, Hong; Lin, Zhi-yong; Qian, Hao

2006-01-01

98

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

99

15 Years of Ground-based UV-visible Observations of Bromine Monoxide Over Harestua, Southern Norway (60°N, 11°E)  

NASA Astrophysics Data System (ADS)

Since 1994, ground-based zenith-sky UV-visible observations of bromine monoxide (BrO) have been performed at the NDACC (Network for the Detection of Atmospheric Composition Change) station of Harestua in Southern Norway (60°N, 11°E). Time-series of low resolution vertical profiles of BrO have been retrieved by applying an optimal estimation profiling technique to zenith-sky observations at twilight. These observations are mainly sensitive to the stratosphere, however information on the tropospheric BrO content can also be retrieved by using, for the spectral analysis, a fixed reference spectrum recorded under clear-sky noon summer conditions. We present an overview of results recently obtained using this observational data set, including extensive comparisons with satellite nadir column and limb profile BrO measurements from OMI, GOME-2, and SCIAMACHY instruments, as well as comparisons with 3-dimensional chemical transport simulations of BrO in both the stratosphere and troposphere. The Harestua long-term data set is also used to study the trend of the bromine loading in the stratosphere. A positive trend of about +2%/year is found before 2001 while a negative trend of about -1%/year is obtained in the 2001-2008 period. This decline is confirmed by collocated SCIAMACHY limb observations. These findings provide firm evidence that the Montreal Protocol restrictions on brominated substances have now reached the stratosphere.

Hendrick, F.; Theys, N.; Canty, T. P.; de Maziere, M. M.; Rozanov, A.; Salawitch, R. J.; Yang, X.; van Roozendael, M.

2009-12-01

100

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 Cu 2+ 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

101

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

SciTech Connect

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

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

2013-02-15

102

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

103

Quantitative characterization of individual microdroplets using surface-enhanced resonance Raman scattering spectroscopy.  

PubMed

Surface-enhanced resonance Raman scattering (SERRS) spectroscopy is a highly sensitive optical technique capable of detecting multiple analytes rapidly and simultaneously. There is significant interest in SERRS detection in micro- and nanotechnologies, as it can be used to detect extremely low analyte concentrations in small volumes of fluids, particularly in microfluidic systems. There is also rapidly growing interest in the field of microdroplets, which promises to offer the analyst many potential advantages over existing technologies for both design and control of microfluidic assays. While there have been rapid advances in both fields in recent years, the literature on SERRS-based detection of individual microdroplets remains lacking. In this paper, we demonstrate the ability to quantitatively detect multiple variable analyte concentrations from within individual microdroplets in real time using SERRS spectroscopy. We also demonstrate the use of a programmable pump control algorithm to generate concentration gradients across a chain of droplets. PMID:22243139

Syme, Christopher D; Martino, Chiara; Yusvana, Rama; Sirimuthu, Narayana M S; Cooper, Jonathan M

2012-02-01

104

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

105

13C NMR spectroscopy for the quantitative determination of compound ratios and polymer end groups.  

PubMed

(13)C NMR spectroscopic integration employing short relaxation delays was evaluated as a quantitative tool to obtain ratios of diastereomers, regioisomers, constitutional isomers, mixtures of unrelated compounds, peptoids, and sugars. The results were compared to established quantitative methods such as (1)H NMR spectroscopic integration, gas chromatography, and high-performance liquid chromatography and were found to be within <3.4% of (1)H NMR spectroscopic values (most examples give results within <2%). Acquisition of the spectra took 2-30 min on as little as 10 mg of sample, proving the general utility of the technique. The simple protocol was extended to include end group analysis of low molecular weight polymers, which afforded results in accordance with (1)H NMR spectroscopy and matrix-assisted laser desorption-ionization time-of-flight spectrometry. PMID:24601654

Otte, Douglas A L; Borchmann, Dorothee E; Lin, Chin; Weck, Marcus; Woerpel, K A

2014-03-21

106

Quantitative analysis of iobitridol in an injectable preparation by 1H NMR spectroscopy.  

PubMed

Nuclear magnetic resonance spectroscopy was used for direct quantitative determination of iobitridol in an injectable formulation. The method was developed on a medium field strength magnet (400MHz) and validation was performed by assessing specificity, accuracy, precision, linearity, stability of samples and robustness. Validation data confirm that the method is highly appropriate for direct quantification of iobitridol in the final formulation. Moreover the method has a good potential for rapid screening analyses due to straightforward experimental setup and lack of any sample pretreatment. PMID:24531005

Borioni, Anna; Gostoli, Gianluca; Bossù, Elena; Sestili, Isabella

2014-06-01

107

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

Microsoft Academic Search

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

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

2010-01-01

108

Quantitative C 2 H 2 measurements in sooty flames using mid-infrared polarization spectroscopy  

Microsoft Academic Search

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\\u000a 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\\u000a McKenna type

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

2010-01-01

109

Quantitative emission from femtosecond microplasmas for laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

110

Laser-induced breakdown spectroscopy for in situ qualitative and quantitative analysis of mineral ores  

NASA Astrophysics Data System (ADS)

In this work, the potential of laser-induced breakdown spectroscopy (LIBS) for discrimination and analysis of geological materials was examined. The research was focused on classification of mineral ores using their LIBS spectra prior to quantitative determination of copper. Quantitative analysis is not a trivial task in LIBS measurement because intensities of emission lines in laser-induced plasmas (LIP) are strongly affected by the sample matrix (matrix effect). To circumvent this effect, typically matrix-matched standards are used to obtain matrix-dependent calibration curves. If the sample set consists of a mixture of different matrices, even in this approach, the corresponding matrix has to be known prior to the downstream data analysis. For this categorization, the multielemental character of LIBS spectra can be of help. In this contribution, a principal component analysis (PCA) was employed on the measured data set to discriminate individual rocks as individual matrices against each other according to their overall elemental composition. Twenty-seven igneous rock samples were analyzed in the form of fine dust, classified and subsequently quantitatively analyzed. Two different LIBS setups in two laboratories were used to prove the reproducibility of classification and quantification. A superposition of partial calibration plots constructed from the individual clustered data displayed a large improvement in precision and accuracy compared to the calibration plot constructed from all ore samples. The classification of mineral samples with complex matrices can thus be recommended prior to LIBS system calibration and quantitative analysis.

Po?ízka, P.; Demidov, A.; Kaiser, J.; Keivanian, J.; Gornushkin, I.; Panne, U.; Riedel, J.

2014-11-01

111

Quantitative analyses of tartaric acid based on terahertz time domain spectroscopy  

NASA Astrophysics Data System (ADS)

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

Cao, Binghua; Fan, Mengbao

2010-10-01

112

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

113

Quantitative analysis of multi-component gas mixture based on AOTF-NIR spectroscopy  

NASA Astrophysics Data System (ADS)

Near Infrared (NIR) spectroscopy analysis technology has attracted many eyes and has wide application in many domains in recent years because of its remarkable advantages. But the NIR spectrometer can only be used for liquid and solid analysis by now. In this paper, a new quantitative analysis method of gas mixture by using new generation NIR spectrometer is explored. To collect the NIR spectra of gas mixtures, a vacuumable gas cell was designed and assembled to Luminar 5030-731 Acousto-Optic Tunable Filter (AOTF)-NIR spectrometer. Standard gas samples of methane (CH 4), ethane (C IIH 6) and propane (C 3H 8) are diluted with super pure nitrogen via precision volumetric gas flow controllers to obtain gas mixture samples of different concentrations dynamically. The gas mixtures were injected into the gas cell and the spectra of wavelength between 1100nm-2300nm were collected. The feature components extracted from gas mixture spectra by using Partial Least Squares (PLS) were used as the inputs of the Support Vector Regress Machine (SVR) to establish the quantitative analysis model. The effectiveness of the model is tested by the samples of predicting set. The prediction Root Mean Square Error (RMSE) of CH 4, C IIH 6 and C 3H 8 is respectively 1.27%, 0.89%, and 1.20% when the concentrations of component gas are over 0.5%. It shows that the AOTF-NIR spectrometer with gas cell can be used for gas mixture analysis. PLS combining with SVR has a good performance in NIR spectroscopy analysis. This paper provides the bases for extending the application of NIR spectroscopy analysis to gas detection.

Hao, Huimin; Zhang, Yong; Liu, Junhua

2007-12-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2006-02-01

115

Attenuated Total Internal Reflectance Infrared Spectroscopy (ATR-FTIR): A Quantitative Approach for Kidney Stone Analysis  

PubMed Central

The impact of kidney stone disease is significant worldwide, yet methods for quantifying stone components remain limited. A new approach requiring minimal sample preparation for the quantitative analysis of kidney stone components has been investigated utilizing attenuated total internal reflectance infrared spectroscopy (ATR-FTIR). Calcium oxalate monohydrate (COM) and hydroxylapatite (HAP), two of the most common constituents of urinary stones, were used for quantitative analysis. Calibration curves were constructed using integrated band intensities of four infrared absorptions versus concentration (weight %). The correlation coefficients of the calibration curves range from 0.997 to 0.93. The limits of detection range from 0.07 ± 0.02% COM/HAP where COM is the analyte and HAP the matrix to 0.26 ± 0.07% HAP/COM where HAP is the analyte and COM the matrix. This study shows that linear calibration curves can be generated for the quantitative analysis of stone mixtures provided the system is well understood especially with respect to particle size. PMID:19589213

Gulley-Stahl, Heather J.; Haas, Jennifer A.; Schmidt, Katherine A.; Evan, Andrew P.; Sommer, André J.

2011-01-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

117

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

118

Quantitative analysis of sesquiterpene lactones in extract of Arnica montana L. by 1H NMR spectroscopy.  

PubMed

(1)H NMR spectroscopy was used as a method for quantitative analysis of sesquiterpene lactones present in a crude lactone fraction isolated from Arnica montana. Eight main components - tigloyl-, methacryloyl-, isobutyryl- and 2-methylbutyryl-esters of helenalin (H) and 11?,13-dihydrohelenalin (DH) were identified in the studied sample. The method allows the determination of the total amount of sesquiterpene lactones and the quantity of both type helenalin and 11?,13-dihydrohelenalin esters separately. Furthermore, 6-O-tigloylhelenalin (HT, 1), 6-O-methacryloylhelenalin (HM, 2), 6-O-tigloyl-11?,13-dihydrohelenalin (DHT, 5), and 6-O-methacryloyl-11?,13-dihydrohelenalin (DHM, 6) were quantified as individual components. PMID:20837387

Staneva, Jordanka; Denkova, Pavletta; Todorova, Milka; Evstatieva, Ljuba

2011-01-01

119

TOPICAL REVIEW: Quantitative electron microscopy and spectroscopy of MgB2 wires and tapes  

NASA Astrophysics Data System (ADS)

In MgB2 the correlation of microstructure with superconducting properties, in particular the critical current density, requires powerful analytical tools. Critical current densities and electrical resistivities of different MgB2 superconductors differ by orders of magnitudes and the current limiting mechanisms have not been fully understood. Granularity of MgB2 is one significant reason for reduced critical current densities and is introduced intrinsically by the anisotropy of Bc2 but also extrinsically by the microstructure of the material. Bc2 enhancement by doping is another important challenge for chemical analysis and, at present, doping levels are not well controlled on the sub-µm scale. In this paper the quantitative electron microscopy and spectroscopy methods essential for the microstructural analysis of MgB2 are described. By quantitative electron microscopy and spectroscopy we mean a combined SEM and TEM analysis that covers various length scales from µm to nm. Contamination-free sample preparation, chemical mapping including B, and advanced chemical quantification using x-ray microanalysis were essential elements of the applied methodology. The methodology was applied to in situ and ex situ MgB2 wires and tapes with and without SiC additives. Quantitative B analysis by EDX spectroscopy was applied quantitatively in the SEM and TEM, which is a major achievement. Although MgB2 is a binary system, the thermodynamics of phase formation is complex, and the complexity is dramatically increased if additives like SiC are used. The small, sub-µm grain sizes of the matrix and secondary phases require TEM methods. However, granularity on the µm scale was also identified and underlines the importance of the combined SEM and TEM studies. Significant differences in the microstructure were observed for in situ and ex situ samples. This holds particularly if SiC was added and yielded Mg2Si for in situ samples annealed at 600-650 °C and Mg-Si-O phases for ex situ samples annealed between 900-1050 °C. Only with such a systematic approach combining a large number of microscopy and spectroscopy methods, could a microstructure critical current density model be established that will be presented in another paper. Four microstructural parameters were identified as relevant for the critical current density of wires and tapes and these were: (1) MgB2 grain size, (2) colony size (a colony is a dense arrangement of MgB2 grains), (3) oxygen content and (4) volume fraction of B-rich secondary phases. MgB2 grain size can only be determined by TEM, while colony size, oxygen content and volume fraction of B-rich secondary phases were determined by SEM methods. The formation of oxides was also studied in detail by TEM methods. The importance of electron microscopy methods in the understanding of the thermodynamics of phase formation in MgB2 as well as in improving the synthesis technology and the superconducting properties of MgB2 wires and tapes is described.

Birajdar, B.; Peranio, N.; Eibl, O.

2008-07-01

120

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

PubMed

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

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

2014-01-30

121

Quantitative classification of cryptosporidium oocysts and giardia cysts in water using UV/vis spectroscopy  

NASA Astrophysics Data System (ADS)

Cryptosporidium and Giardia are enteric protozoa which cause waterborne diseases. To date, the detection of these organisms in water has relied upon microscopic immunofluorescent assay technology which uses antibodies directed against the cyst and oocyst forms of the protozoa. In this paper, the uv/vis extinction spectra of aqueous dispersions of Cryptosporidium and Giardia have been studied to investigate the potential use of light scattering-spectral deconvolution techniques as a rapid method for the identification and quantification of protozoa in water. Examination of purified samples of Cryptosporidium and Giardia suggests that spectral features apparent in the short wavelength region of the uv/vis spectra contain information that may be species specific for each protozoa. The spectral characteristics, as well as the particle size analysis, determined from the same spectra, allow for the quantitative classification, identification, and possibly, the assessment of the viability of the protozoa. To further increase the sensitivity of this technique, specific antibodies direction against these organisms, labelled with FITC and rhodamine are being used. It is demonstrated that uv/vis spectroscopy provides an alternative method for the characterization of Giardia and Cryptosporidium. The simplicity and reproducibility of uv/vis spectroscopy measurements makes this technique ideally suited for the development of on-line instrumentation for the rapid detection of microorganisms in water supplies.

Bacon, Christina P.; Rose, J. B.; Patten, K.; Garcia-Rubio, Luis H.

1995-05-01

122

Characterization of geometrical factors for quantitative angle-resolved photoelectron spectroscopy  

SciTech Connect

For conventional angle-resolved x-ray photoelectron spectroscopy (ARXPS), the area under the core-level peaks depends mainly on the in-depth distribution of chemical species at the top surface of a specimen. But the x-ray photoelectron spectroscopy (XPS) intensity is also affected by tool-related geometrical factors such as the shape of the x-ray beam, the spectrometer analysis volume, and the manipulator rotation axis. Data analysis is therefore typically based on normalization with respect to the signal from the substrate. Here, we present an original method to perform quantitative ARXPS without normalization, involving evaluation of these geometrical factors. The method is illustrated for a multiprobe XPS system using a methodology based on a specific software (XPSGeometry{sup Registered-Sign }), but is a general process that can be adapted to all types of XPS equipment, even those not specifically designed for ARXPS. In that case, this method enables bringing the sample as close as possible to the manipulator axis of rotation in order to perform automatic acquisitions.

Martinez, Eugenie; Herrera-Gomez, Alberto; Allain, Mickael; Renault, Olivier; Faure, Alain; Chabli, Amal; Bertin, Francois [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); CINVESTAV-Queretaro, Libramiento Norponiente 2000, Real de Juriquilla, Queretaro, 76000 (Mexico); CEA, LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

2012-07-15

123

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  

NASA Astrophysics Data System (ADS)

A new dioxo-molybdenum(VI) complex [MoO2(L)(H2O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H2L) and MoO2(acac)2. The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, 1H NMR and 13C 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, 1H NMR and 13C 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 1H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental 1H NMR spectra. However, the 13C 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 13C 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.

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

2012-09-01

124

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

125

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

126

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

127

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

NASA Astrophysics Data System (ADS)

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

Wang, Qiang; Ma, Yehao; Wang, Xiaowei

2012-06-01

128

Quantitative FT-IR spectroscopy of gypsum raw material for industry  

NASA Astrophysics Data System (ADS)

Today quality control (QC) is a big issue for being competitive in the gypsum industry. Knowledge and understanding of the raw material help to enhance the quality and permanence of products. Therefore a rapid, precise and user-friendly FT-IR spectroscopic method for quantitative analysis of gypsum, anhydrite, magnesite and dolomite from the gypsum deposit of Puchberg, Austria is being developed. There are decisive advantages of FT-IR spectroscopy compared to thermogravimetric methods (TG, DTA, DSC) or XRD, which are commonly used for QC, e.g. it is frequently available in industry labs and a spectrum can be obtained in a few minutes, with a minimum of sample preparation. The effects of particle size and ratio of dilution with KBr were investigated in transmission mode, using KBr pellets, as well as in diffuse reflexion mode. Little differences in particle size lead to enormous differences in peak height in transmission mode, but show only little effects in diffuse reflexion. The small amounts of sample used in KBr pellets (e.g. 2 mg sample : 500 mg KBr) also turned out to be disadvantageous, just like the time consuming sample preparation. Measurements in diffuse reflexion with a sample to KBr ratio of 1:10 show promising results for use in standardization, whereas higher dilutions hardly improve the quality, and ratios of 1:5 still show components of specular reflection. The calibration model for quantitative analysis is being constructed measuring various defined mixtures of >98% pure natural minerals (gypsum, magnesite, dolomite), and synthetic materials (anhydrite). The latter was obtained by heating gypsum at 350^oC for 10 h. The synthetic material was chosen, because natural material was not available in sufficient amounts with high purity. The IR method is compared with results achieved with XRD-Rietveld and thermogravimetric methods. Advantages of chemometrical software based on multivariate statistical techniques will be investigated and compared with standard techniques using simple peak fitting methods.

Schwendtner, K.; Libowitzky, E.; Götzinger, M. A.; Koss, S.

2003-04-01

129

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

130

Ultrafast two-photon absorption in organic molecules: Quantitative spectroscopy and applications  

NASA Astrophysics Data System (ADS)

This dissertation explores quantitative two-photon absorption spectroscopy to relate molecular structure with optical properties of organic chromophores. The dissertation describes an advanced fluorescence-based technique for reliable measurements of the two-photon spectra and cross sections. To facilitate the measurements it establishes a set of reference compounds measured with a 15% absolute accuracy covering a broad range of excitation and fluorescence wavelengths. The dissertation shows that in many cases the few-essential-levels model can be successfully applied for the description and interpretation of two-photon absorption spectra and cross sections, at least for the low-energy transitions. The dissertation presents examples of applications of two-photon absorption for volumetric optical storage and cancer tumor detection. It describes the basic principles of the two-photon absorption-based optical memory and limitations imposed on two-photon sensitivity of photochromic materials by a necessity of fast access to the data. It also proposes a novel technique for sensitive detection of cancer cells by using two-photon excitation of near-IR fluorescence of a commercial dye and discusses the mechanisms responsible for differentiation between the normal and the cancer cells. The methods described in this dissertation can be applied to understanding the relations between structure and two-photon absorption strength of individual transitions of organic and biological chromophores, which can be used for design of new materials, maximally adapted for particular applications.

Makarov, Nikolay Sergeevich

131

Quantitative hydrogen analysis of zircaloy-4 in laser-induced breakdown spectroscopy with ambient helium gas  

SciTech Connect

This experiment was carried out to address the need for overcoming the difficulties encountered in hydrogen analysis by means of plasma emission spectroscopy in atmospheric ambient gas. The result of this study on zircaloy-4 samples from a nuclear power plant demonstrates the possibility of attaining a very sharp emission line from impure hydrogen with a very low background and practical elimination of spectral contamination of hydrogen emission arising from surface water and water vapor in atmospheric ambient gas. This was achieved by employing ultrapure ambient helium gas as well as the proper defocusing of the laser irradiation and a large number of repeated precleaning laser shots at the same spot of the sample surface. Further adjustment of the gating time has led to significant reduction of spectral width and improvement of detection sensitivity to {approx}50 ppm. Finally, a linear calibration curve was also obtained for the zircaloy-4 samples with zero intercept. These results demonstrate the feasibility of this technique for practical in situ and quantitative analysis of hydrogen impurity in zircaloy-4 tubes used in a light water nuclear power plant.

Ramli, Muliadi; Fukumoto, Ken-ichi; Niki, Hideaki; Abdulmadjid, Syahrun Nur; Idris, Nasrullah; Maruyama, Tadashi; Kagawa, Kiichiro; Tjia, May On; Pardede, Marincan; Kurniawan, Koo Hendrik; Hedwig, Rinda; Lie, Zener Sukra; Lie, Tjung Jie; Kurniawan, Davy Putra

2007-12-01

132

Quantitative analysis of metformin in antidiabetic tablets by laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Nowadays the production of counterfeit and low quality drugs affects human health and generates losses to pharmaceutical industries and tax revenue losses to government. Currently there are several methods for pharmaceutical product analysis; nevertheless, most of them depend on complex and time consuming steps such as sample preparation. In contrast to conventional methods, Laser-induced breakdown spectroscopy (LIBS) is evaluated as a potential analytical technique for the rapid screening and quality control of anti-diabetic solid formulations. In this paper authors propose a simple method to analyze qualitatively and quantitatively Active Pharmaceutical Ingredients (APIs) such as Metformin hydrochloride. The authors used ten nanosecond duration pulses (FWHM) from a Nd:YAG laser produces the induced breakdown for the analysis. Light is collected and focused into a Cerny-Turner spectrograph and dispersed into an ICCD camera for its detection. We used atomic emissions from Chlorine atoms present only in APIs as analyte signal. The analysis was improved using Bromine as internal standard. Linear calibration curves from synthetic samples were prepared achieving linearity higher than 99%. Our results were compared with HPLC results and validation was performed by statistical methods. The validation analysis suggests that both methods have no significant differences i.e., the proposed method can be implemented for monitoring the pharmaceutical production process in-situ in real time or for inspection and recognition of authenticity.

Contreras, U.; Ornelas-Soto, N.; Meneses-Nava, M. A.; Barbosa-García, O.; López-de-Alba, P. L.; López-Martínez, L.

2011-09-01

133

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

PubMed

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

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

2014-12-10

134

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

135

Quantitative characterisation of pigment mixtures used in art by fibre-optics diffuse-reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

Fibre-optics diffuse reflectance spectroscopy (FORS) was used to characterise pigment mixtures in paints used in art. Measurements are non invasive, without any contact with the sample. The experimental device is portable, therefore measurements can be performed in situ, without moving the work of art under investigation from its conservation place. The protocol was validated thanks to modern gouache paints: 10 pure gouaches were used as references and 27 binary mixtures of these pure gouaches were studied. Reflectance spectra are processed using the Kubelka-Munk theory in order to get scattering and absorption coefficients of the references. Assuming a linear dependance of these optical properties with the pigment volume concentration (PVC) of the components of paint layers, the protocol enables qualitative as well as quantitative interpretation of the reflectance spectra measured on binary mixtures of references. Indeed, for most cases, numerical processing of FORS-measurements performed on a mixture leads to the identification of its components. Besides, once the components are identified, it is possible to compute their respective proportions with an accuracy of 5%.

Dupuis, G.; Menu, M.

2006-06-01

136

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

137

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

138

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

139

Cancer therapy prognosis using quantitative ultrasound spectroscopy and a kernel-based metric  

NASA Astrophysics Data System (ADS)

In this study, a kernel-based metric based on the Hilbert-Schmidt independence criterion (HSIC) is proposed in a computer-aided-prognosis system to monitor cancer therapy effects. In order to induce tumour cell death, sarcoma xenograft tumour-bearing mice were injected with microbubbles followed by ultrasound and X-ray radiation therapy successively as a new anti-vascular treatment. High frequency (central frequency 30 MHz) ultrasound imaging was performed before and at different times after treatment and using spectroscopy, quantitative ultrasound (QUS) parametric maps were derived from the radiofrequency (RF) signals. The intensity histogram of midband fit parametric maps was computed to represent the pre- and post-treatment images. Subsequently, the HSIC-based metric between preand post-treatment samples were computed for each animal as a measure of distance between the two distributions. The HSIC-based metrics computes the distance between two distributions in a reproducing kernel Hilbert space (RKHS), meaning that by using a kernel, the input vectors are non-linearly mapped into a different, possibly high dimensional feature space. Computing the population means in this new space, enhanced group separability (compared to, e.g., Euclidean distance in the original feature space) is ideally obtained. The pre- and post-treatment parametric maps for each animal were thus represented by a dissimilarity measure, in which a high value of this metric indicated more treatment effect on the animal. It was shown in this research that this metric has a high correlation with cell death and if it was used in supervised learning, a high accuracy classification was obtained using a k-nearest-neighbor (k-NN) classifier.

Gangeh, Mehrdad J.; Hashim, Amr; Giles, Anoja; Czarnota, Gregory J.

2014-03-01

140

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

141

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

NASA Astrophysics Data System (ADS)

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

Robles, Francisco E.

142

Impact of pellet thickness on quantitative terahertz spectroscopy of solid samples in a polyethylene matrix.  

PubMed

Pellets composed of different weight-percent (wt-%) of lactose within a polyethylene (PE) matrix are used to examine how the physical thickness of solid samples impact analytical measurements performed over terahertz (THz) frequencies when using time-domain THz spectroscopy. Results indicate that the thickness of each pellet depends on the mass and physical properties of the individual components that comprise the pellet. Thickness of mixture pellets depends on the porosity of the individual pellet components. Porosity measurements presented here for PE and lactose give values of 25.6 ± 0.3 and 14.5 ± 0.1, respectively, which indicate that more air is trapped within the compressed PE matrix compared to that for lactose. This difference in porosity creates different pellet thicknesses for pellets of the same nominal mass but with different relative amounts of PE and lactose. For this binary matrix, the thickness of each pellet is found to be a linear combination of the compressed densities of the individual components. Analysis of the time-domain THz spectra reveals that thinner samples are confounded by a fringe pattern observed in the frequency-domain spectra. This fringe pattern is created by an etalon corresponding to the air/pellet interfaces for the sample in the optical path. Spectra collected from thicker pellets are confounded by a sloping baseline caused by scattering effects within the pellet matrix. The quantitative impact of pellet thickness is determined by comparing the mean standard error of calibration (MSEC) and mean standard error of prediction (MSEP) for a set of leave-three-out cross validation multivariate calibration models based on the partial least-squares (PLS) algorithm. Results indicate that PLS models are capable of analytical measurements with MSEC and MSEP values between 0.04 and 0.20 wt-%. Analysis of spectral variance captured within the corresponding spectral loadings for each model indicates that spectral variance is lowest for the 300 mg samples where the impact of scattering is minimal under conditions when the sample etalon is nonexistent. PMID:23438763

Namkung, Hankyu; Kim, Jaejin; Chung, Hoeil; Arnold, Mark A

2013-04-01

143

The Effects of Protein Environment on the Low Temperature Electronic Spectroscopy of Cytochrome c and Microperoxidase-11  

E-print Network

electric field of the heme pocket, generated by charged and polar groups in the protein. The temperatureThe Effects of Protein Environment on the Low Temperature Electronic Spectroscopy of Cytochrome c-6089 ReceiVed: March 10, 1999; In Final Form: May 17, 1999 Low temperature UV-visible spectra of cytochrome c

Sharp, Kim

144

Quantitative Orientation Measurements in Thin Lipid Films by Attenuated Total Reflection Infrared Spectroscopy  

E-print Network

, namely polarized transmission spectroscopy (Rothschild and Clark, 1979; Chollet and Messier, 1982; Vogel (Golden et al., 1981; Buf- feteau et al., 1991; Blaudez et al., 1993), and polarized attenuated total reflection (ATR) spectroscopy (Harrick, 1967; Fringeli and Gu¨nthard, 1981; Kimura et al., 1986; Ahn

Pezolet, Michel

145

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

146

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

E-print Network

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

Hsu, Wei-Chun

2012-01-01

147

Quantitative analysis of routine chemical constituents in tobacco by near-infrared spectroscopy and support vector machine  

NASA Astrophysics Data System (ADS)

It is important to monitor quality of tobacco during the production of cigarette. Therefore, in order to scientifically control the tobacco raw material and guarantee the cigarette quality, fast and accurate determination routine chemical of constituents of tobacco, including the total sugar, reducing sugar, Nicotine, the total nitrogen and so on, is needed. In this study, 50 samples of tobacco from different cultivation areas were surveyed by near-infrared (NIR) spectroscopy, and the spectral differences provided enough quantitative analysis information for the tobacco. Partial least squares regression (PLSR), artificial neural network (ANN), and support vector machine (SVM), were applied. The quantitative analysis models of 50 tobacco samples were studied comparatively in this experiment using PLSR, ANN, radial basis function (RBF) SVM regression, and the parameters of the models were also discussed. The spectrum variables of 50 samples had been compressed through the wavelet transformation technology before the models were established. The best experimental results were obtained using the (RBF) SVM regression with ? = 1.5, 1.3, 0.9, and 0.1, separately corresponds to total sugar, reducing sugar, Nicotine, and total nitrogen, respectively. Finally, compared with the back propagation (BP-ANN) and PLSR approach, SVM algorithm showed its excellent generalization for quantitative analysis results, while the number of samples for establishing the model is smaller. The overall results show that NIR spectroscopy combined with SVM can be efficiently utilized for rapid and accurate analysis of routine chemical compositions in tobacco. Simultaneously, the research can serve as the technical support and the foundation of quantitative analysis of other NIR applications.

Zhang, Yong; Cong, Qian; Xie, Yunfei; Yang, Jingxiu; Zhao, Bing

2008-12-01

148

Quasi-simultaneous observations of the BL Lac object MK 501 in X-ray, UV, visible, IR and radio frequencies  

NASA Technical Reports Server (NTRS)

Quasi-simultaneous observations of the BL Lacertae (Lac) objects MK 501 were performed for the first time at X-ray, ultraviolet, visible, infrared, and radio frequencies. The observed spectral slope from the X-ray to UV regions is positive and continuous, but that from the mid UV to visible light region becomes gradually flat and possibly turns down toward lower frequencies; the optical radio emission can not be accounted for by a single power law. Several theoretical models were considered for the emission mechanism. A quantitative comparison was performed with the synchrotron-self-Compton model; the total spectrum is found consistent with this model. The spectrum from visible light to X-ray is consistent with synchrotron radiation or with inverse-Compton scattering by a hot thermal cloud of electrons. The continuity of the spectral slope from X-ray to UV implied by the current data suggests that the previous estimates of the total luminosity of this BL Lac object is underestimated by a factor of about three or four.

Kondo, D. M.; Worrall, D. M.; Mushotzky, R. F.; Hackney, R. L.; Hackney, K. H.; Oke, J. B.; Yee, H.; Neugebauer, G.; Matthews, K.; Feldman, P. A.

1980-01-01

149

Ethane and n-butane oxidation over supported vanadium oxide catalysts: An in situ UV-visible diffuse reflectance spectroscopic investigation  

SciTech Connect

The coordination/oxidation states of surface vanadium oxide species on several oxide supports (Al{sub 2}O{sub 3}, ZrO{sub 2}, SiO{sub 2}) during ethane and n-butane oxidation were examined by in situ UV-vis diffuse reflectance spectroscopy (DRS). Only a small amount of the surface V(V)cations are reduced to V(IV)/V(III) cations under present steady-state reaction conditions. The extents of reduction of the surface V(V) species are a strong function of the specific oxide support, V{sub 2}O{sub 5}/ZrO{sub 2} {gt} V{sub 2}O{sub 5}/Al{sub 2}O{sub 5}/Al{sub 2}O{sub 3} {gt} V{sub 2}O{sub 5}/SiO{sub 2}, and also correlate with their reactivities (turnover frequencies) for ethane and n-butane oxidation reactions. For ZrO{sub 2}-supported samples, the polymerized surface vanadia species were found to be more easily reduced than the isolated surface vanadia species in reducing environments (i.e., ethane or n-butane in He), but no significant differences in the extents of reduction were observed under present steady-state reaction conditions (i.e., ethane/O{sub 2}/He or n-butane/O{sub 2}/He). This observation is also consistent with the ethane oxidation catalytic study, which revealed that the polymerization degree, the domain size, of the surface vanadia species does not appear to significantly affect the reactivity of the supported vanadia catalysts for ethane oxidation.

Gao, X.; Banares, M.A.; Wachs, I.E.

1999-12-10

150

[Qualitative and quantitative detection of beet syrup adulteration of honey by near-infrared spectroscopy: a feasibility study].  

PubMed

In order to further investigate the utility of near-infrared spectroscopys (NIRS) in rapidly detecting honey adulteration, near-infrared spectroscopy in combination with chemometric methods was investigated for qualitative and quantitative detection of beet syrup adulteration of honey. Total prediction accuracy of testing set was 90.2% by partial least squares-discriminant analysis (PLS-DA) for authentic and adulterated honey samples. Total prediction accuracy of testing sets was all below 33.3% by different discriminant methods for classes of adulteration level. The quantitative analysis of adulteration level by PLS regression gave satisfying results if adulterated honey samples were got from the same one authentic honey sample: correlation coefficient (r)of actual values versus predicted values was 0.9829 and root mean square error of prediction (RMSEP) was 1.394 2 in testing set, otherwise it gave dissatisfying results for the adulterated samples from different botanical origins or the different samples of the same botanical origins. The results showed that NIRS could be applied for rapid detection of authentic and adulterated honey samples, but not for detection of classes of adulteration level and quantification of adulteration level with beet syrup. PMID:24409707

Li, Shui-Fang; Wen, Rui-Zhi; Yin, Yong; Zhou, Zi; Shan, Yang

2013-10-01

151

Quantitative analyses of glass via laser-induced breakdown spectroscopy in argon  

NASA Astrophysics Data System (ADS)

We demonstrate that elemental analysis of glass with a measurement precision of about 10% can be performed via calibration-free laser-induced breakdown spectroscopy. Therefore, plasma emission spectra recorded during ultraviolet laser ablation of different glasses are compared to the spectral radiance computed for a plasma in local thermodynamic equilibrium. Using an iterative calculation algorithm, we deduce the relative elemental fractions and the plasma properties from the best agreement between measured and computed spectra. The measurement method is validated in two ways. First, the LIBS measurements are performed on fused silica composed of more than 99.9% of SiO2. Second, the oxygen fractions measured for heavy flint and barite crown glasses are compared to the values expected from the glass composing oxides. The measured compositions are furthermore compared with those obtained by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. It is shown that accurate LIBS analyses require spectra recording with short enough delays between laser pulse and detector gate, when the electron density is larger than 1017 cm- 3. The results show that laser-induced breakdown spectroscopy based on accurate plasma modeling is suitable for elemental analysis of complex materials such as glasses, with an analytical performance comparable or even better than that obtained with standard techniques.

Gerhard, C.; Hermann, J.; Mercadier, L.; Loewenthal, L.; Axente, E.; Luculescu, C. R.; Sarnet, T.; Sentis, M.; Viöl, W.

2014-11-01

152

QUANTITATIVE ULTRAVIOLET SPECTROSCOPY IN WEATHERING OF A MODEL POLYESTER-URETHANE COATING. (R828081E01)  

EPA Science Inventory

Spectroscopy was used to quantify the effects of ultraviolet light on a model polyester–urethane coating as it degraded in an accelerated exposure chamber. An explorative calculation of the effective dosage absorbed by the coatings was made and, depending on the quantum...

153

Tropospheric O3, NO2, SO2, HCHO, and CHOCHO from UV/Visible Spectroscopic Measurements: Capabilities and Requirements for Geostationary Pollution Monitoring (Invited)  

NASA Astrophysics Data System (ADS)

In recent years, beginning in 1985, we have developed spaceborne spectrometers capable of measuring the minimal suite of tropospheric polluting gases considered here plus, of course, aerosols and clouds. SCIAMACHY, the GOME instruments, and OMI are all capable of making such measurements, although with limited spatial and spectral sampling. What has been required to do so are stable instruments of moderate spectral resolution (0.2-0.5 nm) and excellent noise performance, covering at least 300-460 nm (the upcoming U.S. OMPS instruments will measure part of the suite of pollutant gases). It has also been necessary to develop the underlying algorithm physics for dynamic in-orbit wavelength and slit function calibrations, Ring effect (Raman scattering) correction, spectral undersampling correction, and improved reference spectra (HITRAN), in order to properly analyze spectra. Final results depend also on accurate fitting techniques, radiative transfer modeling and chemistry and transport modeling. All of these have been developed to the point where low-Earth-orbit measurements are mature, and the capabilities are ripe for application to geostationary (or other geosynchronous) orbits, in order to measure pollution at high temporal and spatial resolution. This talk will demonstrate that the instrumental and algorithmic capabilities we have already developed can be applied directly to geostationary measurements to obtain excellent sensitivities to tropospheric O3, NO2, SO2, HCHO, and CHOCHO (and several other species which are not primary pollutants) with modest requirements for light-collecting capability. The current state of sensitivity, spatial, and temporal requirements for measurements will be discussed. These requirements lead to the instrument requirements: A scalable instrument concept which has been incrementally developed from the measurement requirements, quantitative radiative transfer modeling and fitting studies, and the capabilities we have developed for GOME, SCIAMACHY, OMI, and OMPS will be presented. Orbital considerations, especially relevant to European geosynchronous measurements, will be presented. Finally, the two outstanding needs will be discussed: (1) improved scientific requirements (e.g., providing traceability for AQ forecast improvement and other uses; (2) instrument optical and spectrograph design, including fully-informed choice of detector type.

Chance, K.; Kurosu, T. P.; Liu, X.; Newchurch, M.

2009-12-01

154

Characterization and quantitative analysis of single-walled carbon nanotubes in the aquatic environment using near-infrared fluorescence spectroscopy.  

PubMed

Near infrared fluorescence (NIRF) spectroscopy is capable of sensitive and selective detection of semiconductive, single-walled carbon nanotubes (SWNT) using the unique electronic bandgap properties of these carbon allotropes. We reported here the first detection and quantitation of SWNT in sediment and biota at environmentally relevant concentrations using NIRF spectroscopy. In addition, we utilized this technique to qualitatively characterize SWNT samples before and after ecotoxicity, bioavailability and fate studies in the aquatic environment. Sample preparation prior to NIRF analysis consisted of surfactant-assisted high power ultrasonication. The bile salt sodium deoxycholate (SDC) enabled efficient extraction and disaggregation of SWNT prior to NIRF analysis. The method was validated using standard-addition experiments in two types of estuarine sediments, yielding recoveries between 66 ± 7% and 103 ± 10% depending on SWNT type and coating used, demonstrating the ability to isolate SWNT from complex sediment matrices. Instrument detection limits were determined to be 15 ng mL(-1) SWNT in 2% SDC solution and method detection limits (including a concentration step) were 62 ng g(-1) for estuarine sediment, and 1.0 ?g L(-1) for water. Our work has shown that NIRF spectroscopy is highly sensitive and selective for SWNT and that this technique can be applied to track the environmental and biological fate of this important class of carbon nanomaterial in the aquatic environment. PMID:22970987

Schierz, Ariette; Parks, Ashley N; Washburn, Kathryn M; Chandler, G Thomas; Ferguson, P Lee

2012-11-20

155

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

PubMed

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

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

2014-05-01

156

Quantitative determination of the human breast milk macronutrients by near-infrared Raman spectroscopy  

NASA Astrophysics Data System (ADS)

This work proposes the evaluation of the macronutrient constitution of human breast milk based on the spectral information provided by near-infrared Raman spectroscopy. Human breast milk (5 mL) from a subject was collected during the first two weeks of breastfeeding and stocked in -20°C freezer. Raman spectra were measured using a Raman spectrometer (830 nm excitation) coupled to a fiber based Raman probe. Spectra of human milk were dominated by bands of proteins, lipids and carbohydrates in the 600-1800 cm-1 spectral region. Raman spectroscopy revealed differences in the biochemical constitution of human milk depending on the time of breastfeeding startup. This technique could be employed to develop a classification routine for the milk in Human Milk Banking (HMB) depending on the nutritional facts.

Motta, Edlene d. C. M.; Zângaro, Renato A.; Silveira, Landulfo, Jr.

2012-03-01

157

Quantitative Determination of Chemical Processes by Dynamic Nuclear Polarization Enhanced Nuclear Magnetic Resonance Spectroscopy  

E-print Network

Transfer for Pharmacophore Mapping MRI Magnetic Resonance Imaging MRS Magnetic Resonance Spectroscopy MW Microwave viii NMR Nuclear Magnetic Resonance NOE Nuclear Overhauser Effect pCBA p-chlorobenzaldehyde ppm Parts per million PTD 4... (II-10)) using one assumed value for T1. ............ 38 III-1 Reaction of DPBD with PTD in acetonitrile. The signal intensities of H1 and H1? were monitored in the NMR experiments. .......................... 48 III-2 Stacked plots...

Zeng, Haifeng

2012-07-16

158

Quantitative analysis of bayberry juice acidity based on visible and near-infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Visible and near-infrared (Vis/NIR) reflectance spectroscopy has been investigated for its ability to nondestructively detect acidity in bayberry juice. What we believe to be a new, better mathematic model is put forward, which we have named principal component analysis-stepwise regression analysis-backpropagation neural network (PCA-SRA-BPNN), to build a correlation between the spectral reflectivity data and the acidity of bayberry juice. In this model, the optimum network parameters, such as the number of input nodes, hidden nodes, learning rate, and momentum, are chosen by the value of root-mean-square (rms) error. The results show that its prediction statistical parameters are correlation coefficient (r) of 0.9451 and root-mean-square error of prediction (RMSEP) of 0.1168. Partial least-squares (PLS) regression is also established to compare with this model. Before doing this, the influences of various spectral pretreatments (standard normal variate, multiplicative scatter correction, S. Golay first derivative, and wavelet package transform) are compared. The PLS approach with wavelet package transform preprocessing spectra is found to provide the best results, and its prediction statistical parameters are correlation coefficient (r) of 0.9061 and RMSEP of 0.1564. Hence, these two models are both desirable to analyze the data from Vis/NIR spectroscopy and to solve the problem of the acidity prediction of bayberry juice. This supplies basal research to ultimately realize the online measurements of the juice's internal quality through this Vis/NIR spectroscopy technique.

Shao, Yongni; He, Yong; Mao, Jingyuan

2007-09-01

159

Spectroscopic (FT-IR, FT-Raman, and UV-visible) and quantum chemical studies on molecular geometry, Frontier molecular orbitals, NBO, NLO and thermodynamic properties of 1-acetylindole.  

PubMed

Quantum chemical calculations of ground state energy, geometrical structure and vibrational wavenumbers of 1-acetylindole were carried out using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. The FT-IR and FT-Raman spectra were recorded in the condensed state. The fundamental vibrational wavenumbers were calculated and a good correlation between experimental and scaled calculated wavenumbers has been accomplished. Electric dipole moment, polarizability and first static hyperpolarizability values of 1-acetylindole have been calculated at the same level of theory and basis set. The results show that the 1-acetylindole molecule possesses nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV-Visible spectrum of the molecule was recorded in the region 200-500nm and the electronic properties like HOMO and LUMO energies and composition were obtained using TD-DFT method. The calculated energies and oscillator strengths are in good correspondence with the experimental data. The thermodynamic properties of the compound under investigation were calculated at different temperatures. PMID:24996206

Shukla, Vikas K; Al-Abdullah, Ebtehal S; El-Emam, Ali A; Sachan, Alok K; Pathak, Shilendra K; Kumar, Amarendra; Prasad, Onkar; Bishnoi, Abha; Sinha, Leena

2014-12-10

160

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

Microsoft Academic Search

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

Sylwester Mazurek; Roman Szostak

2006-01-01

161

Accurate determination of reference materials and natural isolates by means of quantitative (1)h NMR spectroscopy.  

PubMed

A fast and precise proton nuclear magnetic resonance (qHNMR) method for the quantitative determination of low molecular weight target molecules in reference materials and natural isolates has been validated using ERETIC 2 (Electronic REference To access In vivo Concentrations) based on the PULCON (PULse length based CONcentration determination) methodology and compared to the gravimetric results. Using an Avance III NMR spectrometer (400 MHz) equipped with a broad band observe (BBO) probe, the qHNMR method was validated by determining its linearity, range, precision, and accuracy as well as robustness and limit of quantitation. The linearity of the method was assessed by measuring samples of l-tyrosine, caffeine, or benzoic acid in a concentration range between 0.3 and 16.5 mmol/L (r(2) ? 0.99), whereas the interday and intraday precisions were found to be ?2%. The recovery of a range of reference compounds was ?98.5%, thus demonstrating the qHNMR method as a precise tool for the rapid quantitation (~15 min) of food-related target compounds in reference materials and natural isolates such as nucleotides, polyphenols, or cyclic peptides. PMID:24559241

Frank, Oliver; Kreissl, Johanna Karoline; Daschner, Andreas; Hofmann, Thomas

2014-03-26

162

Quantitative analysis of bayberry juice acidity based on visible and near-infrared spectroscopy.  

PubMed

Visible and near-infrared (Vis/NIR) reflectance spectroscopy has been investigated for its ability to nondestructively detect acidity in bayberry juice. What we believe to be a new, better mathematic model is put forward, which we have named principal component analysis-stepwise regression analysis-backpropagation neural network (PCA-SRA-BPNN), to build a correlation between the spectral reflectivity data and the acidity of bayberry juice. In this model, the optimum network parameters, such as the number of input nodes, hidden nodes, learning rate, and momentum, are chosen by the value of root-mean-square (rms) error. The results show that its prediction statistical parameters are correlation coefficient (r) of 0.9451 and root-mean-square error of prediction (RMSEP) of 0.1168. Partial least-squares (PLS) regression is also established to compare with this model. Before doing this, the influences of various spectral pretreatments (standard normal variate, multiplicative scatter correction, S. Golay first derivative, and wavelet package transform) are compared. The PLS approach with wavelet package transform preprocessing spectra is found to provide the best results, and its prediction statistical parameters are correlation coefficient (r) of 0.9061 and RMSEP of 0.1564. Hence, these two models are both desirable to analyze the data from Vis/NIR spectroscopy and to solve the problem of the acidity prediction of bayberry juice. This supplies basal research to ultimately realize the online measurements of the juice's internal quality through this Vis/NIR spectroscopy technique. PMID:17805379

Shao, Yongni; He, Yong; Mao, Jingyuan

2007-09-01

163

Quantitative elemental analyses of archaeological materials by laser-induced breakdown spectroscopy (LIBS): an overview  

NASA Astrophysics Data System (ADS)

LIBS is one of the most promising techniques for rapid, in-situ elemental analyses of artworks. It does not require sample preparation, it is almost non destructive (micro sampling) and information both about major and trace elements could be obtained simultaneously. LIBS has been used to recognize the elements present in different archaeological materials and has been also proposed for on-line monitoring during the object cleaning by lasers. Quantitative determination of the material composition can supply useful information to restorers and help the object cataloguing. However, the analytical LIBS measurements on the archaeological materials were rarely reported, mainly due to difficulties to obtain the corresponding matrix-matched standards, required for the initial calibration. Alternatively, Calibration-Free (CF) approach could be used on some class of materials if all the major sample elements are detected and if the laser plasma preserves the material stochiometry. The latter condition is sometimes missing, as in the case of bronzes under nanosecond pulse laser ablation. We have developed a theoretical model for laser ablation of quaternary copper alloys, which allows for correction of the missing plasma stochiometry in CF approach. The model also predicts the optimal calibration for this type of material. In our recent work, we also obtained quantitative LIBS results on marbles by realizing the calibration standards starting from doped CaCO3 powders and by applying the corrections on the plasma parameters, different for the laboratory standards and marbles. Semi-quantitative LIBS results have been also obtained on multi-layered renaissance ceramics by subtraction of the contribution to plasma of each ceramic layer.

Lazic, Violeta; Caneve, Luisa; Colao, Francesco; Fantoni, Roberta; Fornarini, Lucilla; Spizzichino, Valeria

2005-06-01

164

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

PubMed Central

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

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

2012-01-01

165

Comparison of electron energy-loss and quantitative optical spectroscopy on individual optical gold antennas  

NASA Astrophysics Data System (ADS)

Using a rather large set of different individual metallic optical antennas, we compare directly measured electron energy-loss spectra with measured quantitative optical extinction and scattering cross-section spectra on the identical antennas. All antenna resonances lie near 1.4 µm wavelength. In contrast to other reports, we find identical resonance positions for electrons and photons to within the experimental errors. We discuss possible artifacts which can lead to seemingly different resonance positions in experiments. Our experimental results agree well with complete numerical calculations of both sorts of spectra.

Husnik, Martin; von Cube, Felix; Irsen, Stephan; Linden, Stefan; Niegemann, Jens; Busch, Kurt; Wegener, Martin

2013-10-01

166

Qualitative and quantitative control of carbonated cola beverages using ¹H NMR spectroscopy.  

PubMed

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

Maes, Pauline; Monakhova, Yulia B; Kuballa, Thomas; Reusch, Helmut; Lachenmeier, Dirk W

2012-03-21

167

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.

2012-06-01

168

Total reflection x-ray fluorescence spectroscopy (TXRF) a new high sensitivity (PPT) quantitative method for forensic and environmental samples  

SciTech Connect

Total Reflection X-Ray Fluorescence (TYRF) Spectroscopy instrumentation has recently become available on the U.S. commercial market. This x-ray excited method is touted for its sensitivity (parts per trillion), quantitative ability without the need for multi-element standards and lack of response change to matrix element differences. It has been promoted for use in forensic science and on environmental samples. This paper will discuss the results of a blind studies, wherein well characterized samples of forensic interest and environmental water proficiency tests were submitted for determination of elemental composition and concentration. The results indicate that this instrumentation should be considered by those laboratories analyzing materials at low (trace) concentrations or small (microscopical) size.

Kubic, T.A.; Amray, M.S. [ATOMIKA, Bedford, MA (United States); Reus, U. [ATOMKIA Instruments, Munich (Germany)] [and others

1995-12-31

169

Assessment of statistical uncertainty in the quantitative analysis of solid samples in motion using laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Statistical uncertainty in the quantitative analysis of solid samples in motion by laser-induced breakdown spectroscopy (LIBS) has been assessed. For this purpose, a LIBS demonstrator was designed and constructed in our laboratory. The LIBS system consisted of a laboratory-scale conveyor belt, a compact optical module and a Nd:YAG laser operating at 532 nm. The speed of the conveyor belt was variable and could be adjusted up to a maximum speed of 2 m s - 1 . Statistical uncertainty in the analytical measurements was estimated in terms of precision (reproducibility and repeatability) and accuracy. The results obtained by LIBS on shredded scrap samples under real conditions have demonstrated that the analytical precision and accuracy of LIBS is dependent on the sample geometry, position on the conveyor belt and surface cleanliness. Flat, relatively clean scrap samples exhibited acceptable reproducibility and repeatability; by contrast, samples with an irregular shape or a dirty surface exhibited a poor relative standard deviation.

Cabalín, L. M.; González, A.; Ruiz, J.; Laserna, J. J.

2010-08-01

170

Quantitative nanostructural and single-molecule force spectroscopy biomolecular analysis of human-saliva-derived exosomes.  

PubMed

Exosomes are naturally occurring nanoparticles with unique structure, surface biochemistry, and mechanical characteristics. These distinct nanometer-sized bioparticles are secreted from the surfaces of oral epithelial cells into saliva and are of interest as oral-cancer biomarkers. We use high- resolution AFM to show single-vesicle quantitative differences between exosomes derived from normal and oral cancer patient's saliva. Compared to normal exosomes (circular, 67.4 ± 2.9 nm), our findings indicate that cancer exosome populations are significantly increased in saliva and display irregular morphologies, increased vesicle size (98.3 ± 4.6 nm), and higher intervesicular aggregation. At the single-vesicle level, cancer exosomes exhibit significantly (P < 0.05) increased CD63 surface densities. To our knowledge, it represents the first report detecting single-exosome surface protein variations. Additionally, high-resolution AFM imaging of cancer saliva samples revealed discrete multivesicular bodies with intraluminal exosomes enclosed. We discuss the use of quantitative, nanoscale ultrastructural and surface biomolecular analysis of saliva exosomes at single-vesicle- and single-protein-level sensitivities as a potentially new oral cancer diagnostic. PMID:22017459

Sharma, Shivani; Gillespie, Boyd M; Palanisamy, Viswanathan; Gimzewski, James K

2011-12-01

171

Quantitation of Organics in Supercritical Fluid Aging Experiments Using FTIR Spectroscopy  

SciTech Connect

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

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

2004-03-31

172

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

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

173

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

174

[Study on temperature correctional models of quantitative analysis with near infrared spectroscopy].  

PubMed

Effect of enviroment temperature on near infrared spectroscopic quantitative analysis was studied. The temperature correction model was calibrated with 45 wheat samples at different environment temperaturs and with the temperature as an external variable. The constant temperature model was calibated with 45 wheat samples at the same temperature. The predicted results of two models for the protein contents of wheat samples at different temperatures were compared. The results showed that the mean standard error of prediction (SEP) of the temperature correction model was 0.333, but the SEP of constant temperature (22 degrees C) model increased as the temperature difference enlarged, and the SEP is up to 0.602 when using this model at 4 degrees C. It was suggested that the temperature correctional model improves the analysis precision. PMID:16201365

Zhang, Jun; Chen, Hua-cai; Chen, Xing-dan

2005-06-01

175

Quantitative degenerate four-wave mixing spectroscopy: Probes for molecular species  

SciTech Connect

Resonant degenerate four-wave mixing (DFWM) is currently the subject of intensive investigation as a sensitive diagnostic tool for molecular species. DFWM has the advantage of generating a coherent (beam-like) signal which results in null-background detection and provides excellent immunity to background-light interference. Since multiple one-photon resonances are involved in the signal generation process, the DFWM technique can allow sensitive detection of molecules via electronic, vibrational or rotational transitions. These properties combine to make DFWM a widely applicable diagnostic technique for the probing of molecular species. The authors are conducting fundamental and applied investigations of DFWM for quantitative measurements of trace species in reacting gases. During the past year, efforts have been focussed in two areas: (1) understanding the effects of collisional processes on the DFWM signal generation process, and (2) exploring the applicability of infrared DFWM to detect polyatomic molecules via rovibrational transitions.

Farrow, R.; Rakestraw, D.; Paul, P.; Lucht, R.; Danehy, P.; Friedman-Hill, E.; Germann, G. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01

176

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

PubMed Central

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

Kumar, Prashant; Nagarajan, Rajamani

2013-01-01

177

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

178

MR imaging of fat-containing tissues: valuation of two quantitative imaging techniques in comparison with localized proton spectroscopy.  

PubMed

Since lipid protons, consisting mainly of triacylglycerols (TAG), are rather mobile, magnetic resonance imaging (MRI) is ideally suited for the examination of fat-containing tissues such as bone marrow. In contrast to water protons, however, lipid protons are chemically distinct and give rise to at least eight resonance peaks with different T1 and T2 relaxation times in the 1H spectrum. This is why the characterization of fat-containing tissues by quantitative MRI is much more difficult than that of most other tissues. In our study we wanted to examine the accuracy and the potential of a 1H chemical shift imaging (CSI) technique and a multiple spin-echo imaging (MSEI) technique. A stimulated-echo (STEAM) sequence for spatially localized proton spectroscopy was used as the reference method. In the first part of this paper, we describe quantitative imaging experiments which were performed to assess the accuracy of the fat-water separation according to the Dixon method and the bi-exponential decomposition of the MSEI data. For that purpose, we used a two-compartment phantom filled with either an aqueous Gd-DTPA solution and vegetable oil or with two different aqueous Gd-DTPA solutions, respectively. The analysis of the 1H CSI data revealed that the presence of non-methylen protons in neutral fats leads to a slight under-estimation (of about 15%) of the relative fat fraction. The error is described theoretically and verified quantitatively by STEAM measurements. The bi-exponential analysis of the transverse relaxation data, on the other hand, yields reliable T2 values if the relative proton density of both components is higher than 15%. IN the second part of our investigation, the same techniques were applied to acquire data from the subcutaneous fatty tissue, the femoral head, and the lumbar vertebrae of three healthy volunteers. In the bone marrow spectra, only two broad resonances could be resolved; they were superpositions of diverse molecular groups with different T1 and T2 relaxation times. In these cases, localized proton spectroscopy does not provide additional information with respect to 1H CSI. The MSEI data of the three examined fat containing tissue regions were adequately fitted by a bi-exponential function despite the fact that there were much more chemically distinct protons present in fatty tissues. PMID:8231682

Brix, G; Heiland, S; Bellemann, M E; Koch, T; Lorenz, W J

1993-01-01

179

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

PubMed

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

Muthu, S; Elamurugu Porchelvi, E

2013-12-01

180

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

PubMed

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

Saravanan, S; Balachandran, V

2014-09-15

181

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  

NASA Astrophysics Data System (ADS)

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

Muthu, S.; Elamurugu Porchelvi, E.

2013-12-01

182

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

PubMed Central

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

Leitermann, Frank; Syldatk, Christoph; Hausmann, Rudolf

2008-01-01

183

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. PMID:23853680

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

2012-01-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

185

Fast Quantitative Analysis Of Museum Objects Using Laser-Induced Breakdown Spectroscopy And Multiple Regression Algorithms  

NASA Astrophysics Data System (ADS)

The recent development of mobile instrumentation, specifically devoted to in situ analysis and study of museum objects, allows the acquisition of many LIBS spectra in very short time. However, such large amount of data calls for new analytical approaches which would guarantee a prompt analysis of the results obtained. In this communication, we will present and discuss the advantages of statistical analytical methods, such as Partial Least Squares Multiple Regression algorithms vs. the classical calibration curve approach. PLS algorithms allows to obtain in real time the information on the composition of the objects under study; this feature of the method, compared to the traditional off-line analysis of the data, is extremely useful for the optimization of the measurement times and number of points associated with the analysis. In fact, the real time availability of the compositional information gives the possibility of concentrating the attention on the most `interesting' parts of the object, without over-sampling the zones which would not provide useful information for the scholars or the conservators. Some example on the applications of this method will be presented, including the studies recently performed by the researcher of the Applied Laser Spectroscopy Laboratory on museum bronze objects.

Lorenzetti, G.; Foresta, A.; Palleschi, V.; Legnaioli, S.

2009-09-01

186

[Rapid quantitative analysis of hydrocarbon composition of furfural extract oils using attenuated total reflection infrared spectroscopy].  

PubMed

A set of rapid analysis system for hydrocarbon composition of heavy oils was designed using attenuated total reflection FTIR spectrometer and chemometrics to determine the hydrocarbon composition of furfural extract oils. Sixty two extract oil samples were collected and their saturates and aromatics content data were determined according to the standard NB/SH/T0509-2010, then the total contents of resins plus asphaltenes were calculated by the subtraction method in the percentage of weight. Based on the partial least squares (PLS), calibration models for saturates, aromatics, and resin+asphaltene contents were established using attenuated total reflection FTIR spectroscopy, with their SEC, 1.43%, 0.91% and 1.61%, SEP, 1.56%, 1.24% and 1.81%, respectively, meeting the accuracy and repeatability required for the standard. Compared to the present standard method, the efficiency of hydrocarbon composition analysis for furfural extract oils is significantly improved by the new method which is rapid and simple. The system could also be used for other heavy oil analysis, with excellent extension and application foreground. PMID:25269288

Li, Na; Yuan, Hong-Fu; Hu, Ai-Qin; Liu, Wei; Song, Chun-Feng; Li, Xiao-Yu; Song, Yi-Chang; He, Qi-Jun; Liu, Sha; Xu, Xiao-Xuan

2014-07-01

187

Quantitative analysis of arsenic in mine tailing soils using double pulse-laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

A double pulse-laser induced breakdown spectroscopy (DP-LIBS) was used to determine arsenic (As) concentration in 16 soil samples collected from 5 different mine tailing sites in Korea. We showed that the use of double pulse laser led to enhancements of signal intensity (by 13% on average) and signal-to-noise ratio of As emission lines (by 165% on average) with smaller relative standard deviation compared to single pulse laser approach. We believe this occurred because the second laser pulse in the rarefied atmosphere produced by the first pulse led to the increase of plasma temperature and populations of exited levels. An internal standardization method using a Fe emission line provided a better correlation and sensitivity between As concentration and the DP-LIBS signal than any other elements used. The Fe was known as one of the major components in current soil samples, and its concentration varied not substantially. The As concentration determined by the DP-LIBS was compared with that obtained by atomic absorption spectrometry (AAS) to evaluate the current LIBS system. They are correlated with a correlation coefficient of 0.94. The As concentration by the DP-LIBS was underestimated in the high concentration range (>1000 mg-As/kg). The loss of sensitivity that occurred at high concentrations could be explained by self-absorption in the generated plasma.

Kwak, Ji-hyun; Lenth, Christoph; Salb, Christian; Ko, Eun-Joung; Kim, Kyoung-Woong; Park, Kihong

2009-10-01

188

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

PubMed

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

Mazzei, Pierluigi; Piccolo, Alessandro

2012-06-01

189

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

190

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

PubMed

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

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

2013-12-01

191

Quantitative analysis of adhesive resin in the hybrid layer using Raman spectroscopy  

PubMed Central

The objective was to determine absolute molar concentration of adhesive resin components in the hybrid layer by establishing methods based on Raman spectroscopy fundamentals. The hybrid layer was treated as a three-component system consisting of collagen and an adhesive resin containing two monomers. Adhesive standard specimens and Raman peak area ratios obtained with a 785 nm excitation wavelength were used to construct separate calibration curves for comonomer relative molar concentration and Bis-GMA absolute molar concentration. Since collagen and water had no measurable peaks in the fingerprint region, a dilution coefficient Kj was defined to describe their impact on Raman peak area and to calculate HEMA absolute molar concentration. Methodology was validated using an analogous system containing acetone/ethanol/water. The absolute molar concentration of Bis-GMA and HEMA decreased 87% and 83%, respectively, from the top quarter to the middle of the hybrid layer. Additionally, less Bis-GMA penetrated the hybrid layer than HEMA, as indicated by the ?20% decrease in comonomer molar concentration ratio between the adhesive resin layer and the top half of the hybrid layer. Lack of complete monomer infiltration will further challenge dentin-adhesive bond longevity. PMID:20186729

Zou, Yuan; Armstrong, Steven R.; Jessop, Julie L. P.

2009-01-01

192

Non-invasive quantitative assessment of oxidative metabolism in quadriceps muscles by near infrared spectroscopy  

PubMed Central

Background—Near infrared spectroscopy can be used in non-invasive monitoring of changes in skeletal muscle oxygenation in exercising subjects. Objective—To evaluate whether this method can be used to assess metabolic capacity of muscles. Two distinctive variables abstracted from a curve of changes in muscle oxygenation were assessed. Methods—Exercise on a cycle ergometer was performed by 18 elite male athletes and eight healthy young men. A measuring probe was placed on the skin of the quadriceps muscle to measure reflected light at two wavelengths (760 and 850 nm), so that the relative index of muscle oxygenation could be calculated. Exercise intensity was increased from 50 W in 50 W increments until the subject was exhausted. During exercise, changes in muscle oxygenation and blood lactate concentration were recorded. The following two variables for assessment of muscle oxygenation were then abstracted and analysed by plotting curves of changes in muscle oxygenation: the rate of recovery of muscle oxygen saturation (RR) and the relative value of the effective decrease in muscle oxygenation (Deff). Results—Data analysis showed a correlation between muscle oxygenation and blood lactate concentration at the various exercise intensities and verified the feasibility of the experiment. Data for the athletes were compared with those for the controls using the Aspin-Welch test of significance; t = 2.3 and 2.86 for RR and Deff respectively. There were significant differences (p = 0.05) between the athletes and the control group with respect to these two variables. Conclusion—RR and Deff may be distinctive variables that can be used to characterise muscle oxidative metabolism during human body movement. Key Words: recovery; muscle; oxygen saturation; exercise; elite athletes PMID:11726485

Ding, H; Wang, G; Lei, W; Wang, R; Huang, L; Xia, Q; Wu, J

2001-01-01

193

Quantitative Soil Carbon Analysis with in Situ Laser-Induced Breakdown Spectroscopy by Multivariate Analysis  

NASA Astrophysics Data System (ADS)

The Earth's oceans, forests, agricultural lands and other natural areas absorb about half of the carbon dioxide emitted from anthropogenic sources. Terrestrial carbon sequestration strategies are immediately available to bridge the gap between current terrestrial sequestration capacity and high-capacity geologic sequestration projects available in 10 to 20 years. Terrestrial carbon sequestration strategies consist of implementing land management practices aimed at decreasing CO2 emitted into the atmosphere and developing advanced measurement tools to inventory and monitor carbon processes in soils and biota. Laser-Induced Breakdown Spectroscopy (LIBS) is one of the analytical tools used to determine the total soil carbon in samples within the Big Sky and Southwest Carbon Sequestration Regional Partnerships. LIBS involves focusing a Nd:YAG laser operating at 1064nm onto the surface of the sample. The laser ablates material from the surface, generating an expanding plasma containing electronically excited ions, atoms, and small molecules. As these electronically excited species relax back to the ground state, they emit light at wavelengths characteristic of the species present in the sample. Some of this emission is directed into one of three dispersive spectrometers. The experiments discussed in this paper were completed with a person portable LIBS instrument designed and built at Los Alamos National Laboratory that uses a Kigre Laser (25mJ/pulse) and an Ocean Optics HR2000 dispersive spectrometer. This instrument was used to probe samples collected from Illinois (no-till loam), Michigan (no-till clay), and North Dakota (reduced-till sand). A new multivariate analysis technique was employed to extract concentrations to 0.5%C with significantly greater statistical accuracy than conventional univariate techniques. These MVA techniques appear to completely compensate for these matrix effects because the analysis identifies the correlations between the spectra (independent variables), the individual elements of interest (dependent variables such as Si) as well as the other elements in the matrix.

Harris, R. D.; Clegg, S. M.; Barefield, J. E.; Fessenden-Rahn, J. E.; Wiens, R. C.; Ebinger, M. H.

2007-12-01

194

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

PubMed

A procedure for the quantitative determination of captopril and prednisolone in commercial tablets based on partial least squares (PLS) and principal component regression (PCR) treatment of FT-Raman spectroscopic data is described. In the studied medicines active pharmaceutical ingredients (APIs) constitute 4.2-16.7% of the tablet mass. Results obtained from calibration models built using unnormalised spectra were compared with the values found when an internal standard was added to each sample and the spectra were normalised by its selected band intensity at maximum or integrated. To appraise the quality of the models the relative standard error of predictions (RSEPs) were calculated for calibration and testing data sets. For captopril determination these were 1.8-2.2% (2.1-2.3%) and 2.7-3.1% (2.7-3.6%), respectively for the different PLS (PCR) models. For prednisolone these errors amounted to 1.8-2.1% (2.6-3.5%) and 3.2-3.7% (3.7-5.9%), respectively. Three commercial preparations of captopril containing 12.5mg and one 25mg of API per tablet were quantified using developed models. Found captopril contents, calculated versus results of iodometric titration, was equal 99.2-101.2% (99.2-102.0%), for the different PLS (PCR) calibration models and the different preparations. Quantification of prednisolone tablets, declared content 5mg per tablet, on the basis of PLS (PCR) models gave API amount, calculated versus results of UV-vis method, in the 99.0-101.0% (98.0-102.0%) range. PMID:16253463

Mazurek, Sylwester; Szostak, Roman

2006-03-18

195

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

NASA Astrophysics Data System (ADS)

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

Manceau, Alain; Nagy, Kathryn L.

2012-12-01

196

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

197

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

PubMed

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

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

2013-12-01

198

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

USGS Publications Warehouse

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

Clark, Roger N.; Swayze, Gregg A.; Leifer, Ira; Livo, K. Eric; Kokaly, Raymond; Hoefen, Todd; Lundeen, Sarah; Eastwood, Michael; Green, Robert O.; Pearson, Neil; Sarture, Charles; McCubbin, Ian; Roberts, Dar; Bradley, Eliza; Steele, Denis; Ryan, Thomas; Dominguez, Roseanne

2010-01-01

199

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

200

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

PubMed

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 (r(2)=0.714, slope=0.92, p<0.001), and the bias between the two techniques is -2.83 mL min(-1)100 g(-1) (CI(0.95): -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. PMID:20615043

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

2010-01-01

201

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

PubMed

Laser-induced breakdown spectroscopy (LIBS) is a feasible remote sensing technique used for mineral analysis in some unapproachable places where in situ probing is needed, such as analysis of radioactive elements in a nuclear leak or the detection of elemental compositions and contents of minerals on planetary and lunar surfaces. Here a compact custom 15 m focus optical component, combining a six times beam expander with a telescope, has been built, with which the laser beam of a 1064 nm Nd?;?YAG laser is focused on remote minerals. The excited LIBS signals that reveal the elemental compositions of minerals are collected by another compact single lens-based signal acquisition system. In our remote LIBS investigations, the LIBS spectra of an unknown ore have been detected, from which the metal compositions are obtained. In addition, a multi-spectral line calibration (MSLC) method is proposed for the quantitative analysis of elements. The feasibility of the MSLC and its superiority over a single-wavelength determination have been confirmed by comparison with traditional chemical analysis of the copper content in the ore. PMID:25239065

Wan, Xiong; Wang, Peng

2014-10-01

202

Artificial neural network for Cu quantitative determination in soil using a portable Laser Induced Breakdown Spectroscopy system  

NASA Astrophysics Data System (ADS)

Laser Induced Breakdown Spectroscopy (LIBS) is an advanced analytical technique for elemental determination based on direct measurement of optical emission of excited species on a laser induced plasma. In the realm of elemental analysis, LIBS has great potential to accomplish direct analysis independently of physical sample state (solid, liquid or gas). Presently, LIBS has been easily employed for qualitative analysis, nevertheless, in order to perform quantitative analysis, some effort is still required since calibration represents a difficult issue. Artificial neural network (ANN) is a machine learning paradigm inspired on biological nervous systems. Recently, ANNs have been used in many applications and its classification and prediction capabilities are especially useful for spectral analysis. In this paper an ANN was used as calibration strategy for LIBS, aiming Cu determination in soil samples. Spectra of 59 samples from a heterogenic set of reference soil samples and their respective Cu concentration were used for calibration and validation. Simple linear regression (SLR) and wrapper approach were the two strategies employed to select a set of wavelengths for ANN learning. Cross validation was applied, following ANN training, for verification of prediction accuracy. The ANN showed good efficiency for Cu predictions although the features of portable instrumentation employed. The proposed method presented a limit of detection (LOD) of 2.3 mg dm - 3 of Cu and a mean squared error (MSE) of 0.5 for the predictions.

Ferreira, Edilene C.; Milori, Débora M. B. P.; Ferreira, Ednaldo J.; Da Silva, Robson M.; Martin-Neto, Ladislau

2008-10-01

203

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

PubMed Central

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

Yang, Jaeyoung; Palla, Mirko; Bosco, Filippo Giacomo; Rindzevicius, Tomas; Alstr?m, Tommy Sonne; Schmidt, Michael Stenbaek; Boisen, Anja; Ju, Jingyue; Lin, Qiao

2013-01-01

204

Spectroscopy  

NSDL National Science Digital Library

This site describes the theory and practice of IR and NMR spectroscopy for classroom and laboratory instruction. Although it is written for a course at the University of Colorado, Boulder, this site is appropriate for anyone doing analytical measurements with infrared or NMR.

2011-08-05

205

Note: Alignment/focus dependent core-line sensitivity for quantitative chemical analysis in hard x-ray photoelectron spectroscopy using a hemispherical electron analyzer  

SciTech Connect

X-ray photoelectron spectroscopy is an established technique for quantitative chemical analysis requiring accurate peak intensity analysis. We present evidence of focus/alignment dependence of relative peak intensities for peaks over a broad kinetic energy range with a hemispherical electron analyzer operated in a position imaging mode. A decrease of over 50% in the Ag 2p{sub 3/2} to Ag 3d ratio is observed in a Ag specimen. No focus/alignment dependence is observed when using an angular imaging mode, necessitating the use of angular mode for quantitative chemical analysis.

Weiland, Conan; Browning, Raymond; Karlin, Barry A.; Fischer, Daniel A.; Woicik, Joseph C. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2013-03-15

206

Laser-induced emission spectroscopy of matrix-isolated carbon molecules: Experimental setup and new results on C3  

Microsoft Academic Search

We have studied small carbon molecules using a matrix-isolation technique. Our experimental setup is described in detail. The carbon clusters were produced by evaporating graphite and trapping the carbon-vapor molecules in solid argon, where molecular growth could be induced by controlled matrix annealing. To identify the produced molecules, absorption spectroscopy in the ultraviolet (UV)-visible and infrared (IR) spectral ranges was

Ivo Cermák; Markus Förderer; Iva Cermáková; Stefan Kalhofer; Helmut Stopka-Ebeler; Gerold Monninger; Wolfgang Krätschmer

1998-01-01

207

Characterisation of in vivo ovarian cancer models by quantitative 1H magnetic resonance spectroscopy and diffusion-weighted imaging.  

PubMed

Magnetic resonance imaging (MRI) and spectroscopy (MRS) offer powerful approaches for detecting physiological and metabolic alterations in malignancies and help investigate underlying molecular mechanisms. Research on epithelial ovarian carcinoma (EOC), the gynaecological malignancy with the highest death rate characterised by frequent relapse and onset of drug resistance, could benefit from application of these molecular imaging approaches. In this study, MRI/MRS were used to characterise solid tumour models obtained by subcutaneous (s.c.) or intraperitoneal (i.p.) implantation of human SKOV3.ip cells in severe combined immunodeficiency (SCID) mice. In vivo MRI/MRS, ex vivo magic-angle-spinning (MAS), and in vitro (1)H-NMR measurements were carried out at 4.7 T, 9.4 T, and 9.4/16.5 T, respectively. MRI evaluation was performed by T1-, T2-, and diffusion-weighted (DW) multislice spin-echo imaging. The in vivo (1)H spectra of all tumour models showed a prominent resonance of total choline-containing metabolites (tCho). Quantitative in vivo MRS of both i.p. and s.c. SKOV3.ip xenografts showed that the mean tCho content was in the 2.9-4.5 mM range, with a mean PCho/tCho ratio of 0.99 ± 0.01 [23 examinations, 14-34 days post injection (dpi)], in good agreement with ex vivo and in vitro analyses. Myo-inositol ranged between 11.7 and 17.0 mM, with a trend towards higher values in i.p. xenografts at 14-16 dpi. The average apparent diffusion coefficient (ADC) values of SKOV3.ip xenografts [1.64 ± 0.11 (n = 9, i.p.) and 1.58 ± 0.03 x10(-3) mm(2)/s (n = 7, s.c.)] were in agreement with values reported for tumours from patients with EOC, while the mean vascular signal fraction (VSF) was lower (? 4%), probably due to the more rapid growth of preclinical models. Both s.c. and i.p. xenografts are valuable preclinical models for monitoring biochemical and physiopathological changes associated with in vivo EOC tumour growth and response to therapy, which may serve as the basis for further clinical development of noninvasive MR approaches. PMID:22020805

Canese, Rossella; Pisanu, Maria Elena; Mezzanzanica, Delia; Ricci, Alessandro; Paris, Luisa; Bagnoli, Marina; Valeri, Barbara; Spada, Massimo; Venditti, Massimo; Cesolini, Albino; Rodomonte, Andrea; Giannini, Massimo; Canevari, Silvana; Podo, Franca; Iorio, Egidio

2012-04-01

208

Ultraviolet-Visible and Fluorescence Spectroscopy Techniques Are Important Diagnostic Tools during the Progression of Atherosclerosis: Diet Zinc Supplementation Retarded or Delayed Atherosclerosis  

PubMed Central

Background. In this study, we examined whether UV-visible and fluorescence spectroscopy techniques detect the progression of atherosclerosis in serum of rabbits fed on high-cholesterol diet (HCD) and HCD supplemented with zinc (HCD + Zn) compared with the control. Methods. The control rabbits group was fed on 100?g/day of normal diet. The HCD group was fed on Purina Certified Rabbit Chow supplemented with 1.0% cholesterol plus 1.0% olive oil (100?g/day) for the same period. The HCD + Zn group was fed on normal Purina Certified Rabbit Chow plus 1.0% cholesterol and 1.0% olive oil supplemented with 470?ppm Zn for the same feeding period. UV-visible and fluorescence spectroscopy and biochemistry in Rabbit's blood serum and blood hematology were measured in Rabbit's blood. Results. We found that the fluorescent peak of HCD shifted toward UV-visible wavelength compared with the control using fluorescent excitation of serum at 192?nm. In addition, they showed that supplementation of zinc (350?ppm) restored the fluorescent peak closely to the control. By using UV-visible spectroscopy approach, we found that the peak absorbance of HCD (about 280?nm) was higher than that of control and that zinc supplementation seemed to decrease the absorbance. Conclusions. This study demonstrates that ultraviolet-visible and fluorescence spectroscopy techniques can be applied as noninvasive techniques on a sample blood serum for diagnosing or detecting the progression of atherosclerosis. The Zn supplementation to rabbits fed on HCD delays or retards the progression of atherosclerosis. Inducing anemia in rabbits fed on HCD delays the progression of atherosclerosis. PMID:24350281

Abdelhalim, Mohamed Anwar K.; Moussa, Sherif A. Abdelmottaleb; AL-Mohy, Yanallah Hussain

2013-01-01

209

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

EPA Science Inventory

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

210

Rapid and quantitative detection of the microbial spoilage of beef by Fourier transform infrared spectroscopy and machine learning  

Microsoft Academic Search

Beef is a commercially important and widely consumed muscle food and central to the protein intake of many societies. In the food industry no technology exists for the rapid and accurate detection of microbiologically spoiled or contaminated beef. Fourier transform infrared (FT-IR) spectroscopy is a rapid, reagentless and non-destructive analytical technique whose continued development is resulting in manifold applications across

David I. Ellis; David Broadhurst; Royston Goodacre

2004-01-01

211

Quantitative Surface Analysis of NBS Standard Materials and Mt. St. Helens Ash by Electron Spectroscopy for Chemical Analysis  

Microsoft Academic Search

Results are presented which develop a quantitative method of surface analysis by ESCA for complex heterogeneous systems. Calibration and application of the method to determination of surface weight percentages are discussed. Mt. St. Helens Ash is used to authenticate the method; results agree with bulk analysis to ±20%. Results from NBS standard materials are used to establish detection limits of

Joseph A. Gardella Jr; David M. Hercules

1983-01-01

212

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

213

Skin Melanin, Hemoglobin, and Light Scattering Properties can be Quantitatively Assessed In Vivo Using Diffuse Reflectance Spectroscopy  

Microsoft Academic Search

Noninvasive and real-time analysis of skin properties is useful in a wide variety of applications. In particular, the quantitative assessment of skin in terms of hemoglobin and melanin content, as well as in terms of its light scattering properties, is a challenging problem in dermatology. We present here a technique for examining human skin, based on the in vivo measurement

George Zonios; Julie Bykowski; Nikiforos Kollias

2001-01-01

214

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

215

Standardization and validation of a new atomic absorption spectroscopy technique for determination and quantitation of Aluminium adjuvant in immunobiologicals  

Microsoft Academic Search

In the present study, Aluminium quantification in immunobiologicals has been described using atomic absorption spectroscopy (AAS) technique. The assay was found to be linear in 25–125?g\\/ml Aluminium range. The procedure was found to be accurate for different vaccines with recoveries of external additions ranging between 93.26 and 103.41%. The mean Limit of Variation (L.V.) for both intra- and inter-assay precision

Arti Mishra; Sumir Rai Bhalla; Sameera Rawat; Vivek Bansal; Rakesh Sehgal; Sunil Kumar

2007-01-01

216

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

217

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

NASA Astrophysics Data System (ADS)

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

Nawar, Said; Buddenbaum, Henning; Hill, Joachim

2014-05-01

218

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

219

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

NASA Astrophysics Data System (ADS)

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 the range of the applied GC reference method. In most cases the multiple coefficients of determination ( R2) are >0.97. Using the IR fingerprint region (900-1400 cm -1) a qualitative discrimination of the individual chemotypes is possible already by visual judgement without to apply any chemometric algorithms.The described rapid and non-destructive methods can be applied in industry to control very easily purifying, blending and redistillation processes of the mentioned essential oils.

Schulz, Hartwig; Quilitzsch, Rolf; Krüger, Hans

2003-12-01

220

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

2013-10-15

221

Quantitative analysis of Ni, Zr and Ba in soil by combing neuro-genetic approach and laser induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

With the combination of neuro-genetic approach and laser-induced breakdown spectroscopy (LIBS), an improved method is proposed to predict the concentrations of Ni, Zr and Ba in soil samples. In this method, an artificial neural network (ANN) based on gradient descent with momentum and adaptive learning rate back propagation (GDMABP) algorithm is used. Simultaneously, an optimization strategy based on genetic algorithm (GA) is employed for selecting number of neurons in hidden layer and momentum coefficient in GDMABP ANN and to obtain an optimized network. Subsequently, the network is used to predict concentration of Ni, Zr and Ba from the tested LIBS data. The approach of neuro-genetic for LIBS analysis is described in detail. The predicted results are compared with those obtained from conventional calibration curve method. Overall, the method of combining neuro-genetic approach with LIBS is capable of predicting elemental concentration.

Shen, Qinmei; Zhou, Weidong; Li, Kexue

2010-11-01

222

Depth-dependent calibration for quantitative elemental depth profiling of copper alloys using laser-induced plasma spectroscopy  

NASA Astrophysics Data System (ADS)

This work presents new calibration procedures for deep elemental depth profile analysis of bronze artifacts. A simple ablation model is developed for the estimation of the ablation rate and hence for deriving the depth spatial calibration scale. Elemental quantification is obtained through the construction of calibration surfaces, using reference samples of known composition, relating laser-induced plasma spectroscopy (LIPS) intensity ratios, content of atomic species and number of laser pulses. Such a method represents a refinement of the standard LIPS quantification approach based on calibration curves, which is extended here to the generation of significantly deep craters into the material under investigation up to several hundred microns. The depth dependence of the calibration surfaces measured is discussed in the framework of a simplified model of depth-dependent plasma temperature.

Agresti, Juri; Siano, Salvatore

2014-10-01

223

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. PMID:23110183

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

2012-01-01

224

Quantitative determination of chlorpromazine. HCl in tablets, spansules, injectables, and bulk chemical by nuclear magnetic resonance spectroscopy.  

PubMed

A nuclear magnetic resonance (NMR) procedure is described for the quantitative analysis of chlorpromazine. HCl in bulk chemical as well as in final dosage forms--tablets, spansules, and injectables. The method is based on measurement of a characteristic signal of chlorpromazine relative to an internal standard. Three different internal standards are specified: Cyclohexane was selected because of the convenience and rapidity with which samples could be prepared for assay. Piperonal was used to verify the method and to show that precision and accuracy were not affected by the volatility of the cyclohexane. Tetramethylammonium bromide was used as an internal standard for Thorazine injectable. No interferences were found from stearates and other tablet excipients. The NMR procedure provides a simple, direct, and specific assay with a precision of +/- 1-2%. PMID:621193

Zarembo, J E; Warren, R J; Staiger, D B

1978-01-01

225

[A quantitative method for evaluating the structure and conformational stability of proteins by second derivative UV-spectroscopy].  

PubMed

A quantitative method is suggested for estimating the structure and conformational stability of proteins based on the individual absorbance of Tyr residues in the second derivative UV spectra. Subtilisins Carlsberg, BPN' and 72 were chosen as the model proteins. The values of the increase of the Tyr absorption at 282.3 nm upon the total denaturation of the proteins made it possible to calculate the number of the exposed and "buried" tyrosine residues in the native proteins. A mathematical model of spectrum changes during the transition of Tyr residues from the "buried" to exposed form is suggested. The method is useful for the determination of the denaturation constants of proteins bearing "buried" tyrosine residues. PMID:8166752

Shevchenko, A A; Kost, O A; Kazanskaia, N F

1994-03-01

226

Recovery and quantitative detection of thiabendazole on apples using a surface swab capture method followed by surface-enhanced Raman spectroscopy.  

PubMed

We developed a rapid and simple method which combines a surface swab capture method and surface-enhanced Raman spectroscopy for recovery and quantitative detection of thiabendazole on apple surfaces. The whole apple surface was swabbed and the swab was vortexed in methanol releasing the pesticide. Silver dendrites were then added to bind the pesticide and used for enhancing the Raman signals. The recovery of the surface swab method was calculated to be 59.4-76.6% for intentionally contaminated apples at different levels (0.1, 0.3, 3, and 5 ppm, ?g/g per weight). After considering the releasing factor (66.6%) from the swab, the final accuracy of the swab-SERS method was calculated to be between 89.2% and 115.4%. This swab-SERS method is simple, sensitive, rapid (?10 min), and quantitative enough for QA/QC in plant procedure. This can be extended to detect other pesticides on raw agricultural produce like pears, carrots, and melons etc. PMID:24262524

He, Lili; Chen, Tuo; Labuza, Theodore P

2014-04-01

227

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

NASA Astrophysics Data System (ADS)

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

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

228

Standardization and validation of a new atomic absorption spectroscopy technique for determination and quantitation of aluminium adjuvant in immunobiologicals.  

PubMed

In the present study, Aluminium quantification in immunobiologicals has been described using atomic absorption spectroscopy (AAS) technique. The assay was found to be linear in 25-125 microg/ml Aluminium range. The procedure was found to be accurate for different vaccines with recoveries of external additions ranging between 93.26 and 103.41%. The mean Limit of Variation (L.V.) for both intra- and inter-assay precision was calculated to be 1.62 and 2.22%, respectively. Further the procedure was found to be robust in relation to digestion temperature, alteration in acid (HNO(3) and H(2)SO(4)) ratio used for sample digestion and storage of digested vaccine samples up to a period of 15 days. After validation, AAS method was compared for its equivalency with routinely used complexometric titration method. On simultaneously applying on seven different groups of both bacterial and viral vaccines, viz., DPT, DT, TT, Hepatitis-A and B, Antirabies vaccine (cell culture) and tetravalent DPT-Hib, a high degree of positive correlation (+0.85-0.998) among AAS and titration methods was observed. Further AAS method was found to have an edge over complexometric titration method that a group of vaccines, viz., ARV (cell culture, adsorbed) and Hepatitis-A, in which Aluminium estimation is not feasible by pharmacopoeial approved complexometric titration method (possibly due to some interference in the sample matrix), this newly described and validated AAS assay procedure delivered accurate and reproducible results. PMID:17644407

Mishra, Arti; Bhalla, Sumir Rai; Rawat, Sameera; Bansal, Vivek; Sehgal, Rakesh; Kumar, Sunil

2007-10-01

229

Remote quantitative analysis of cerium through a shielding window by stand-off laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Laser-Induced Breakdown Spectroscopy (LIBS) has been considered in many applications in nuclear industry. LIBS can be an ideal technique for analyzing the inaccessible nuclear materials typically located behind a shielding window. We report the effect of optical transmittance of the shielding window on the analytical performances of stand-off LIBS for the preliminary surrogate sample of demonstration pyrochemical process, a mixture of cerium oxide (CeO2) and potassium chloride (KCl). A pulsed laser beam was focused on the surface of the sample located 1.45 m away from the stand-off LIBS device. The laser-induced plasma emission was collected through a Schmidt-Cassegrain telescope. LIBS spectra were obtained in an open path and through the shielding window. Univariate calibration curves were obtained using the integrated area of partially resolved Ce I and II lines. The limits of detection (LOD) for Ce were estimated to be 0.046 and 0.061 wt.% for the open-path and through-window analysis, respectively. We found that the through-window LOD is mainly influenced by the optical transmittance of the shielding window and therefore, the through-window LOD can be predicted from the open-path LOD and the optical transmittance of the shielding window. Also, multivariate calibration using partial least squares regression was successfully applied. The quality of calibration could be improved by the multivariate analysis.

Gong, Yongdeuk; Choi, Daewoong; Han, Bo-Young; Yoo, Jonghyun; Han, Song-Hee; Lee, Yonghoon

2014-10-01

230

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

231

Rapid and quantitative detection of the microbial spoilage in milk using Fourier transform infrared spectroscopy and chemometrics.  

PubMed

Microbiological safety plays a very significant part in the quality control of milk and dairy products worldwide. Current methods used in the detection and enumeration of spoilage bacteria in pasteurized milk in the dairy industry, although accurate and sensitive, are time-consuming. FT-IR spectroscopy is a metabolic fingerprinting technique that can potentially be used to deliver results with the same accuracy and sensitivity, within minutes after minimal sample preparation. We tested this hypothesis using attenuated total reflectance (ATR), and high throughput (HT) FT-IR techniques. Three main types of pasteurized milk - whole, semi-skimmed and skimmed - were used and milk was allowed to spoil naturally by incubation at 15 degrees C. Samples for FT-IR were obtained at frequent, fixed time intervals and pH and total viable counts were also recorded. Multivariate statistical methods, including principal components-discriminant function analysis and partial least squares regression (PLSR), were then used to investigate the relationship between metabolic fingerprints and the total viable counts. FT-IR ATR data for all milks showed reasonable results for bacterial loads above 10(5) cfu ml(-1). By contrast, FT-IR HT provided more accurate results for lower viable bacterial counts down to 10(3) cfu ml(-1) for whole milk and, 4 x 10(2) cfu ml(-1) for semi-skimmed and skimmed milk. Using FT-IR with PLSR we were able to acquire a metabolic fingerprint rapidly and quantify the microbial load of milk samples accurately, with very little sample preparation. We believe that metabolic fingerprinting using FT-IR has very good potential for future use in the dairy industry as a rapid method of detection and enumeration. PMID:18810291

Nicolaou, Nicoletta; Goodacre, Royston

2008-10-01

232

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

233

Investigation of noise-induced instabilities in quantitative biological spectroscopy and its implications for non-invasive glucose monitoring  

PubMed Central

Over the past decade, optical spectroscopy has been employed in combination with multivariate chemometric models to investigate a wide variety of diseases and pathological conditions, primarily due to its excellent chemical specificity and lack of sample preparation requirements. Despite promising results in several proof-of-concept studies, its translation to the clinical setting has often been hindered by inadequate accuracy of the conventional spectroscopic models. To address this issue and the possibility of curved (non-linear) effects in the relationship between the concentrations of the analyte of interest and the mixture spectra (due to fluctuations in sample and environmental conditions), support vector machine-based least squares non-linear regression (LS-SVR) has been recently proposed. In this paper, we investigate the robustness of this methodology to noise-induced instabilities and present an analytical formula for estimating modeling precision as a function of measurement noise and model parameters. This formalism can be readily used to evaluate uncertainty in information extracted from spectroscopic measurements, particularly important for rapid-acquisition biomedical applications. Subsequently, using field data (Raman spectra) acquired from glucose clamping study on an animal model subject, we perform the first systematic investigation of the relative effect of additive interference components (namely, noise in prediction spectra, calibration spectra and calibration concentrations) on the prediction error of non-linear spectroscopic models. Our results show that LS-SVR method gives more accurate results and is substantially more robust to additive noise when compared with conventional regression methods such as partial least-squares regression (PLS), when careful selection of the LS-SVR model parameters are performed. We anticipate that these results will be useful for uncertainty estimation in similar biomedical applications where the precision of measurements and its response to noise in the dataset is as important, if not more so, than the generic accuracy level. PMID:22950485

Barman, Ishan; Dingari, Narahara Chari; Singh, Gajendra Pratap; Soares, Jaqueline S.; Dasari, Ramachandra R.; Smulko, Janusz M.

2014-01-01

234

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

235

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

2008-03-01

236

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

237

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

238

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 Central

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 13C=18O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequen cies 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 linewidths 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 linewidth. Narrower linewidths 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.

2012-01-01

239

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

240

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

PubMed

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

Peerapattana, Jomjai; Otsuka, Kuniko; Otsuka, Makoto

2013-07-01

241

UV, visible and IR laser interaction with gelatine  

Microsoft Academic Search

In this work we investigate the effects on gelatine films of nanosecond pulsed laser irradiation at different laser wavelengths from the UV to the IR at 248, 266, 355, 532 and 1064 nm. We compared gelatines differing in gel strength values (Bloom 75 and 225) and in crosslinking degree. Formation of bubbles at the wavelengths in the UV (248 and

M. Oujja; E. Rebollar; C. Abrusci; A. DelAmo; F. Catalina; M. Castillejo

2007-01-01

242

UV, visible and IR laser interaction with gelatine  

NASA Astrophysics Data System (ADS)

In this work we investigate the effects on gelatine films of nanosecond pulsed laser irradiation at different laser wavelengths from the UV to the IR at 248, 266, 355, 532 and 1064 nm. We compared gelatines differing in gel strength values (Bloom 75 and 225) and in crosslinking degree. Formation of bubbles at the wavelengths in the UV (248 and 266 nm), melting and resolidification at 355 nm, and formation of craters by ablation in the VIS and IR (532 and 1064 nm) are the observed morphological changes. On the other hand, changes of the fluorescence behaviour of the films upon UV irradiation reveal chemical modifications of photolabile chromophores.

Oujja, M.; Rebollar, E.; Abrusci, C.; DelAmo, A.; Catalina, F.; Castillejo, M.

2007-04-01

243

AFOS: Probing the UV-Visible Potential of Antarctic Plateau  

NASA Astrophysics Data System (ADS)

AFOS (Antarctic Fibre Optic Spectrometer) is a 30cm Newtonian telescope which injects light through six 30m long optical fibres onto a 240-800nm spectrograph and 1024x256 pixel CCD camera. First deployed to Admundsen-Scott base in the summer of 1998 the telescope is mounted on a dual-telescope alt-az mount and has been designed to probe the suitability of the atmosphere above South Pole for astronomy in the UV and Visible wavelength regions. Improved and refitted in 2000/2001 AFOS has successfully collected data from the 2000 lunar eclipse above the South Pole and this data is presented here. A season of data observing a number of bright standard A and O-type stars was collected during the winter of 2002 and continues during the winter months of 2003. These observations have been designed to probe the UV-cutoff wavelength atmospheric absorption due to oxygen and water and the effect of auroral emissions on observations. The initial results of these obervations are also presented.

Dempsey, Jessica T.; Storey, John W.; Ashley, Michael C.; Burton, Michael G.; Jarnyk, Mark; Hovey, Gary

244

UV, VISIBLE, AND INFRARED SPECTRAL EMISSIONS IN HYBRID ROCKET PLUMES  

Microsoft Academic Search

A survey was made of the spectral emissions from a 2 x 10 inch labscale hybrid rocket motor system. The emissions in the Ultraviolet-Visible (300-750 nm), Near Infrared (750-1100 nm), and Mid Infrared (2-16 ?m) regions were studied. Baseline emissions were found to consist of the sodium and potassium atomic lines, present due to the use of silica phenolic insulators,

M. Keith Hudson; Robert B. Shanks; Dallas H. Snider; Diana M. Lindquist; Chris Luchini; Sterling Rooke

245

8-m UV\\/visible\\/IR space telescope  

Microsoft Academic Search

This paper presents a conceptual design of a next generation large space telescope. A 8-m aperture telescope orbiting Earth at an altitude of 134,000 km would offer dramatic improvements over the Hubble Space Telescope (HST) in sensitivity, resolution, spectral range (1.2 micrometers - 40 micrometers ), sky coverage, and viewing efficiency. The proposed design is characterized by an effective solar

Antoni K. Jakubowski; P. Mohan; R. K. Kapania; Paul Crisafulli; Daniel Hammerand

1995-01-01

246

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

247

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

248

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

249

Oriented Single-Crystal Nuclear Resonance Vibrational Spectroscopy of [Fe(TPP)(MI)(NO)]: Quantitative Assessment of the trans Effect of NO  

PubMed Central

This paper presents oriented single-crystal Nuclear Resonance Vibrational Spectroscopy (NRVS) data for the six-coordinate (6C) ferrous heme-nitrosyl model complex [57Fe(TPP)(MI)(NO)] (1; TPP2? = tetraphenylporphyrin dianion; MI = 1-methylimidazole). The availability of these data enables for the first time the detailed simulation of the complete NRVS data, including the porphyrin-based vibrations, of a 6C ferrous heme-nitrosyl, using our quantum chemistry centered normal coordinate analysis (QCC-NCA). Importantly, the Fe-NO stretch is split by interaction with a porphyrin-based vibration into two features, observed at 437 and 472 cm?1. The 437 cm?1 feature is strongly out-of-plane (oop) polarized and shows an 15N18O isotope shift of 8 cm?1, and is therefore assigned to ?(Fe-NO). The admixture of Fe-N-O bending character is small. Main contributions to the Fe-N-O bend are observed in the 520 – 580 cm?1 region, distributed over a number of in-plane (ip) polarized porphyrin-based vibrations. The main component, assigned to ?ip(Fe-N-O), is identified with the feature at 563 cm?1. The Fe-N-O bend also shows strong mixing with the Fe-NO stretching internal coordinate, as evidenced by the oop NRVS intensity in the 520 – 580 cm?1 region. Very accurate normal mode descriptions of ?(Fe-NO) and ?ip(Fe-N-O) have been obtained in this study. These results contradict previous interpretations of the vibrational spectra of 6C ferrous heme-nitrosyls where the higher energy feature at ~550 cm?1 had usually been associated with ?(Fe-NO). Furthermore, these results provide key insight into NO binding to ferrous heme active sites in globins and other heme proteins, in particular with respect to (a) the effect of hydrogen bonding to the coordinated NO, and (b) changes in heme dynamics upon NO coordination. [Fe(TPP)(MI)(NO)] constitutes an excellent model system for ferrous NO adducts of myoglobin (Mb) mutants where the distal histidine (His64) has been removed. Comparison to the reported vibrational data for wild-type (wt) Mb-NO then shows that the effect of H-bonding to coordinated NO is weak, and mostly leads to a polarization of the ?/?* orbitals of bound NO. In addition, the observation that ?ip(Fe-N-O) does not correlate well with ?(N-O) can be traced back to the very mixed nature of this mode. The Fe-N(imidazole) stretching frequency is observed at 149 cm?1 in [Fe(TPP)(MI)(NO)], and spectral changes upon NO binding to five-coordinate ferrous heme active sites are discussed. The obtained high-quality force constants for the Fe-NO and N-O bonds of 2.57 and 11.55 mdyn/Å can further be compared to those of corresponding 5C species, which allows for a quantitative analysis of the ? trans interaction between the proximal imidazole (His) ligand and NO. This is key for the activation of the NO sensor soluble guanylate cyclase. Finally, DFT methods are calibrated against the experimentally determined vibrational properties of the Fe-N-O subunit in 1. DFT is in fact incapable of reproducing the vibrational energies and normal mode descriptions of the Fe-N-O unit well, and thus, DFT-based predictions of changes in vibrational properties upon heme-modification or other perturbations of these 6C complexes have to be treated with caution. PMID:20586416

Silvernail, Nathan; Alp, E. Ercan; Sturhahn, Wolfgang; Zhao, Jiyong

2010-01-01

250

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

PubMed

This paper presents oriented single-crystal Nuclear Resonance Vibrational Spectroscopy (NRVS) data for the six-coordinate (6C) ferrous heme-nitrosyl model complex [(57)Fe(TPP)(MI)(NO)] (1; TPP(2-) = tetraphenylporphyrin dianion; MI = 1-methylimidazole). The availability of these data enables for the first time the detailed simulation of the complete NRVS data, including the porphyrin-based vibrations, of a 6C ferrous heme-nitrosyl, using our quantum chemistry centered normal coordinate analysis (QCC-NCA). Importantly, the Fe-NO stretch is split by interaction with a porphyrin-based vibration into two features, observed at 437 and 472 cm(-1). The 437 cm(-1) feature is strongly out-of-plane (oop) polarized and shows a (15)N(18)O isotope shift of 8 cm(-1) and is therefore assigned to nu(Fe-NO). The admixture of Fe-N-O bending character is small. Main contributions to the Fe-N-O bend are observed in the 520-580 cm(-1) region, distributed over a number of in-plane (ip) polarized porphyrin-based vibrations. The main component, assigned to delta(ip)(Fe-N-O), is identified with the feature at 563 cm(-1). The Fe-N-O bend also shows strong mixing with the Fe-NO stretching internal coordinate, as evidenced by the oop NRVS intensity in the 520-580 cm(-1) region. Very accurate normal mode descriptions of nu(Fe-NO) and delta(ip)(Fe-N-O) have been obtained in this study. These results contradict previous interpretations of the vibrational spectra of 6C ferrous heme-nitrosyls where the higher energy feature at approximately 550 cm(-1) had usually been associated with nu(Fe-NO). Furthermore, these results provide key insight into NO binding to ferrous heme active sites in globins and other heme proteins, in particular with respect to (a) the effect of hydrogen bonding to the coordinated NO and (b) changes in heme dynamics upon NO coordination. [Fe(TPP)(MI)(NO)] constitutes an excellent model system for ferrous NO adducts of myoglobin (Mb) mutants where the distal histidine (His64) has been removed. Comparison to the reported vibrational data for wild-type (wt) Mb-NO then shows that the effect of H bonding to the coordinated NO is weak and mostly leads to a polarization of the pi/pi* orbitals of bound NO. In addition, the observation that delta(ip)(Fe-N-O) does not correlate well with nu(N-O) can be traced back to the very mixed nature of this mode. The Fe-N(imidazole) stretching frequency is observed at 149 cm(-1) in [Fe(TPP)(MI)(NO)], and spectral changes upon NO binding to five-coordinate ferrous heme active sites are discussed. The obtained high-quality force constants for the Fe-NO and N-O bonds of 2.57 and 11.55 mdyn/A can further be compared to those of corresponding 5C species, which allows for a quantitative analysis of the sigma trans interaction between the proximal imidazole (His) ligand and NO. This is key for the activation of the NO sensor soluble guanylate cyclase. Finally, DFT methods are calibrated against the experimentally determined vibrational properties of the Fe-N-O subunit in 1. DFT is in fact incapable of reproducing the vibrational energies and normal mode descriptions of the Fe-N-O unit well, and thus, DFT-based predictions of changes in vibrational properties upon heme modification or other perturbations of these 6C complexes have to be treated with caution. PMID:20586416

Lehnert, Nicolai; Sage, J Timothy; Silvernail, Nathan; Scheidt, W Robert; Alp, E Ercan; Sturhahn, Wolfgang; Zhao, Jiyong

2010-08-01

251

Distinguishing the core from the shell in MnO x \\/MnO y and FeO x \\/MnO x core\\/shell nanoparticles through quantitative electron energy loss spectroscopy (EELS) analysis  

Microsoft Academic Search

The structural and chemical characterization of inverted bi-magnetic MnOx(antiferromagnetic)\\/MnOy(ferrimagnetic) and FeOx(soft-ferrimagnetic)\\/MnOx(hard-ferrimagnetic) core\\/shell nanoparticles has been carried out by means of scanning transmission electron microscopy with electron energy loss spectroscopy analysis, (S)TEM-EELS. Quantitative EELS was applied to assess the local composition of the nanoparticles by evaluating the local Mn oxidation state based on the Mn L3\\/L2 peak intensity ratio and the

S. Estradé; Ll. Yedra; A. López-Ortega; M. Estrader; G. Salazar-Alvarez; M. D. Baró; J. Nogués; F. Peiró

252

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

NASA Astrophysics Data System (ADS)

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

Poldi, G.; Caglio, S.

2013-06-01

253

Quantitative solid-state analysis of three solid forms of ranitidine hydrochloride in ternary mixtures using Raman spectroscopy and X-ray powder diffraction.  

PubMed

The aim of the study was to develop a reliable quantification procedure for mixtures of three solid forms of ranitidine hydrochloride using X-ray powder diffraction (XRPD) and Raman spectroscopy combined with multivariate analysis. The effect of mixing methods of the calibration samples on the calibration model quality was also investigated. Thirteen ternary samples of form 1, form 2 and the amorphous form of ranitidine hydrochloride were prepared in triplicate to build a calibration model. The ternary samples were prepared by three mixing methods (a) manual mixing (MM) and ball mill mixing (BM) using two (b) 5 mm (BM5) or (c) 12 mm (BM12) balls for 1 min. The samples were analyzed with XRPD and Raman spectroscopy. Principal component analysis (PCA) was used to study the effect of mixing method, while partial least squares (PLS) regression was used to build the quantification models. PCA score plots showed that, in general, BM12 resulted in the narrowest sample clustering indicating better sample homogeneity. In the quantification models, the number of PLS factors was determined using cross-validation and the models were validated using independent test samples with known concentrations. Multiplicative scattering correction (MSC) without scaling gave the best PLS regression model for XPRD, and standard normal variate (SNV) transformation with centering gave the best model for Raman spectroscopy. Using PLS regression, the root mean square error of prediction (RMSEP) values of the best models were 5.0-6.9% for XRPD and 2.5-4.5% for Raman spectroscopy. XRPD and Raman spectroscopy in combination with PLS regression can be used to quantify the amount of single components in ternary mixtures of ranitidine hydrochloride solid forms. Raman spectroscopy gave better PLS regression models than XRPD, allowing a more accurate quantification. PMID:19081220

Chieng, Norman; Rehder, Sönke; Saville, Dorothy; Rades, Thomas; Aaltonen, Jaakko

2009-01-15

254

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

255

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

256

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

257

A composition-independent quantitative determination of the water content in silicate glasses and silicate melt inclusions by confocal Raman spectroscopy  

Microsoft Academic Search

A new approach was developed to measure the water content of silicate glasses using Raman spectroscopy, which is independent\\u000a of the glass matrix composition and structure. Contrary to previous studies, the compositional range of our studied silicate\\u000a glasses was not restricted to rhyolites, but included andesitic, basaltic and phonolitic glasses. We used 21 glasses with\\u000a known water contents for calibration.

Zoltán Zajacz; Werner Halter; Wim J. Malfait; Olivier Bachmann; Robert J. Bodnar; Marc M. Hirschmann; Charles W. Mandeville; Yann Morizet; Othmar Müntener; Peter Ulmer; James D. Webster

2005-01-01

258

Structural Analysis of Wheat Straw Lignin by Quantitative 31 P and 2D NMR Spectroscopy. The Occurrence of Ester Bonds and ?-O-4 Substructures  

Microsoft Academic Search

By combining mild alkaline hydrolysis with quantitative 31P NMR we have been able to arrive at a protocol for determining the various ester linkages and their relative contributions to the overall structure of wheat straw lignin. Additional information on the identity and location of these bonds was sought by the application of GC\\/MS and two-dimensional 13C-1H heterocorrelation NMR experiments. Milled

Claudia Crestini; Dimitris S. Argyropoulos

1997-01-01

259

Detection and quantitative analysis of chemical species in Hanford tank materials using Raman spectroscopy technology: FY94, January 1, 1994--March 31, 1995  

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.

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

1995-09-12

260

Optical spectroscopy study of damage induced in 4H-SiC by swift heavy ion irradiation.  

PubMed

Single crystals of 4H-SiC were irradiated with swift heavy ions (332 MeV Ti, 106 MeV Pb and 2.7 GeV U) in the electronic energy loss regime. The resulting damage was investigated with UV-visible optical absorption spectroscopy and micro-Raman spectroscopy. The evolution of the Raman data with fluence shows an accumulation of isolated point defects without amorphization of the material and a partial recrystallization of the structure, but only at the lowest fluence. Furthermore, the longitudinal optical phonon-plasmon coupling mode disappears upon irradiation, suggesting a strong perturbation of the electronic structure. This evolution is consistent with the optical bandgap decrease and the Urbach edge broadening that was also previously observed for the irradiation with 4 MeV Au ions. PMID:22369869

Sorieul, S; Kerbiriou, X; Costantini, J-M; Gosmain, L; Calas, G; Trautmann, C

2012-03-28

261

A flow system for the on-line quantitative measurement of the retention of dosage forms on biological surfaces using spectroscopy and image analysis.  

PubMed

Measuring the retention, or residence time, of dosage forms to biological tissue is commonly a qualitative measurement, where no real values to describe the retention can be recorded. The result of this is an assessment that is dependent upon a user's interpretation of visual observation. This research paper outlines the development of a methodology to quantitatively measure, both by image analysis and by spectrophotometric techniques, the retention of material to biological tissues, using the retention of polymer solutions to ocular tissue as an example. Both methods have been shown to be repeatable, with the spectrophotometric measurement generating data reliably and quickly for further analysis. PMID:22425677

Cave, Richard A; Cook, Joseph P; Connon, Che J; Khutoryanskiy, Vitaliy V

2012-05-30

262

Near-infrared Raman spectroscopy to detect anti-Toxoplasma gondii antibody in blood sera of domestic cats: quantitative analysis based on partial least-squares multivariate statistics  

NASA Astrophysics Data System (ADS)

Toxoplasmosis is an important zoonosis in public health because domestic cats are the main agents responsible for the transmission of this disease in Brazil. We investigate a method for diagnosing toxoplasmosis based on Raman spectroscopy. Dispersive near-infrared Raman spectra are used to quantify anti-Toxoplasma gondii (IgG) antibodies in blood sera from domestic cats. An 830-nm laser is used for sample excitation, and a dispersive spectrometer is used to detect the Raman scattering. A serological test is performed in all serum samples by the enzyme-linked immunosorbent assay (ELISA) for validation. Raman spectra are taken from 59 blood serum samples and a quantification model is implemented based on partial least squares (PLS) to quantify the sample's serology by Raman spectra compared to the results provided by the ELISA test. Based on the serological values provided by the Raman/PLS model, diagnostic parameters such as sensitivity, specificity, accuracy, positive prediction values, and negative prediction values are calculated to discriminate negative from positive samples, obtaining 100, 80, 90, 83.3, and 100%, respectively. Raman spectroscopy, associated with the PLS, is promising as a serological assay for toxoplasmosis, enabling fast and sensitive diagnosis.

Duarte, Janaína; Pacheco, Marcos T. T.; Villaverde, Antonio Balbin; Machado, Rosangela Z.; Zângaro, Renato A.; Silveira, Landulfo

2010-07-01

263

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

264

Electronic spectroscopy study and molecular docking simulation of the interaction of terthiophene with DNA  

NASA Astrophysics Data System (ADS)

We have performed a study by electronic spectroscopy and molecular docking simulation of the interaction of terthiophene with DNA, modelled as short oligonucleotide sequences containing either the guanine-cytosine or the adenine-thymine motif. We demonstrated that the presence of TT gives rise to a non-vanished increase of the melting temperature of highly polymerized DNA. From this result, we investigated the interaction of TT with the 16-mer oligonucleotides ds(dC-dG) 8 and ds(dA-dT) 8 using UV-visible and fluorescence emission spectroscopy. UV-visible titrations suggested intercalation of TT into ds(dA-dT) 8 and possibility of both intercalation and groove binding in the case of ds(dC-dG) 8. The fluorescence spectra demonstrated that TT cannot remove ethidium from both oligonucleotides, while the analysis of the fluorescence emission of TT evidenced sequence selectivity. Thus, the obtained results in the case of ds(dA-dT) 8 were compatible with intercalation, while the results for ds(dG-dC) 8 suggested the existence of charge-transfer processes between the nucleic bases and the ligand. These processes are favoured by an intercalative binding, although interaction by the grooves is not discarded. In any case, our results suggested a different intercalation mode for these sequences, which was also supported by the docked structures. We built two modified 12-mer oligonucleotides having a hole suitable to host an aromatic planar system as TT. In the model obtained with ds(dA-dT) 6 the longest axis of TT was perpendicular to the direction of the hydrogen bonds between the strands. However, in the docked structure with ds(dG-dC) 6 the TT axis was parallel to the hydrogen bonds, which could favour the ?-? charge-transfer processes.

López Navarrete, J. T.; Casado, J.; Ramírez, F. J.

2007-05-01

265

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

2008-04-01

266

A quantitative analysis of protein secondary structure of photosystem II particles and light-harvesting complex of chloroplast thylakoid membranes by FT-IR spectroscopy  

NASA Astrophysics Data System (ADS)

We report the preliminary results of protein conformational analysis of photosystem II (PSII) particles and light-harvesting complex (LHC-II) of chloroplast thylakoid membranes isolated from fresh spinach in aqueous solution at neutral pH. FT-IR spectroscopy, with its self-deconvolution and second derivative resolution enhancement as well as curve-fitting procedures, was used in the amide I region (1700-1600 cm-1), to determine the amount of each conformation present in coexistence. Spectroscopic data have shown the domination of the ?-helix (1656 cm-1) to be a major conformational component in both PSII (64%) and LHC-II (48%) systems. The ?-sheet (1626-1640 cm-1), with 17% for PSII and 21% for LHC-II, and the turn structure (1670-1680 cm-1), with 23% for LHC-II and 13% for PSII, with ?-antiparallel (1689-1691 cm-1) 8% for LHC-II and 6% for PSII, were the minor conformations present in aqueous solution.

Nahar, S.; Tajmir-Riahi, H. A.; Carpentier, R.

1994-12-01

267

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

268

Development of Transmission Raman Spectroscopy towards the in line, high throughput and non-destructive quantitative analysis of pharmaceutical solid oral dose.  

PubMed

Transmission Raman spectroscopy (TRS) is a recently introduced analytical technique to pharmaceutical analysis permitting volumetric sampling by non-destructive means. Here we demonstrate experimentally, for the first time, the enhanced speed of quantification of pharmaceutical tablets by an order of magnitude compared with conventional TRS. This is achieved using an enhancing element, "photon diode", avoiding the loss of laser photons at laser coupling interface. The proof-of-concept experiments were performed on a complex mixture consisting of 5 components (3 APIs and 2 excipients) with nominal concentrations ranging between 0.4 and 89%. Acquisition times as short as 0.01 s were reached with satisfactory quantification accuracy for all the sample components. Results suggest that even faster sampling speeds would be achievable for components with stronger Raman scattering cross sections or with higher laser powers. This major improvement in speed of volumetric analysis enables high throughput deployment of TRS for in line quality control applications within the batch or continuous manufacturing process and facilitating non-destructive analysis of large fractions. PMID:25360447

Griffen, Julia A; Owen, Andrew W; Matousek, Pavel

2014-12-01

269

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

PubMed

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

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

2013-09-01

270

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

271

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

272

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

273

On Quantitizing  

PubMed Central

Quantitizing, commonly understood to refer to the numerical translation, transformation, or conversion of qualitative data, has become a staple of mixed methods research. Typically glossed are the foundational assumptions, judgments, and compromises involved in converting disparate data sets into each other and whether such conversions advance inquiry. Among these assumptions are that qualitative and quantitative data constitute two kinds of data, that quantitizing constitutes a unidirectional process essentially different from qualitizing, and that counting is an unambiguous process. Among the judgments are deciding what and how to count. Among the compromises are balancing numerical precision with narrative complexity. The standpoints of “conditional complementarity,” “critical remediation,” and “analytic alternation” clarify the added value of converting qualitative data into quantitative form. PMID:19865603

Sandelowski, Margarete; Voils, Corrine I.; Knafl, George

2009-01-01

274

Direct and quantitative absorptive spectroscopy of nanowires  

E-print Network

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

Tong, Jonathan Kien-Kwok

2012-01-01

275

Quantitative VUV spectroscopy of Cl2  

NASA Technical Reports Server (NTRS)

The photoabsorption and fluorescence cross sections of Cl2 were measured in the 105-145 nm region using synchrotron radiation as a light source. The oscillator strengths for the major absorption bands were calculated from the measured absorption cross sections. The measured oscillator strengths for the 2 3Pi u and 2 1Pi u - X 1Sigma(+)g transitions agree quite well with the theoretical values. The absorption spectrum was analyzed in accord with the excited electronic states calculated by Peyerimhoff and Buenker (1981). The Rydberg series converging to the first and second ionization potentials were classified. The vibrational levels of the 2 1Sigma(+)u ionic state were determined up to v prime = 15 from the fluorescence excitation spectrum. It was observed that a band with peak at 108.3 nm produces VUV fluorescence, but it produces UV fluorescence only by a collisional excitation process.

Lee, L. C.; Suto, M.; Tang, K. Y.

1986-01-01

276

Journal of Quantitative Spectroscopy & Radiative Transfer ] (  

E-print Network

constants will be of great utility to high-spectral- resolution IR remote sensing as well as radiative; Ammonium sulfate; Ammonium nitrate; Sulfuric acid; Nitric acid; Infrared remote sensing 1. Introduction Infrared (IR) remote sensing by ground-based, airborne and satellite sensors to determine geophysical

277

Journal of Quantitative Spectroscopy & Radiative Transfer ] (  

E-print Network

tropospheric aerosol; Effective medium approximations; Infrared remote sensing 1. Introduction Internally mixed rules that are commonly used in modeling optical constants of aerosol mixtures either in remote sensing. These findings will be of practical use in remote sensing and radiation transfer/climate studies as well as help

278

Quantitative spectroscopy for detection of cervical dysplasia  

E-print Network

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

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

2009-01-01

279

Spectroscopy: Nanoscale terahertz spectroscopy  

NASA Astrophysics Data System (ADS)

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

Shigekawa, Hidemi; Yoshida, Shoji; Takeuchi, Osamu

2014-11-01

280

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

281

On Quantitizing  

ERIC Educational Resources Information Center

"Quantitizing", commonly understood to refer to the numerical translation, transformation, or conversion of qualitative data, has become a staple of mixed methods research. Typically glossed are the foundational assumptions, judgments, and compromises involved in converting disparate data sets into each other and whether such conversions advance…

Sandelowski, Margarete; Voils, Corrine I.; Knafl, George

2009-01-01

282

Development of a novel combined fluorescence and reflectance spectroscopy system for guiding high-grade glioma resections: confirmation of capability in lab experiments  

NASA Astrophysics Data System (ADS)

Total resection of glioblastoma multiform (GBM), the most common and aggressive malignant brain tumor, is challenging among other things due to difficulty in intraoperative discrimination between normal and residual tumor cells. This project demonstrates the potential of a system based on a combination of autofluorescence and diffuse reflectance spectroscopy to be useful as an intraoperative guiding tool. In this context, a system based on 5 LEDs coupled to optical fibers was employed to deliver UV/visible light to the sample sequentially. Remitted light from the tissue; including diffuse reflected and fluorescence of endogenous and exogenous fluorophores, as well as its photobleaching product, is transmitted to one photodiode and four avalanche photodiodes. This instrument has been evaluated with very promising results by performing various tissue-equivalent phantom laboratory and clinical studies on skin lesions.

Mousavi, Monirehalsadat; Xie, Haiyan; Xie, Zhiyuan; Brydegaard, Mikkel; Axelsson, Johan; Andersson-Engels, Stefan

2013-11-01

283

Synthesis of silver and silver/gold anisotropic nanostructures for surface enhanced Raman spectroscopy applications.  

PubMed

We are reporting the one pot chemical reduction synthesis of isotropic spherical silver nanoparticles of size around 4-8 nm and some anisotropic nanostructures of silver and silver-gold systems such as silver nanoprisms of size around 60-80 nm, silver/gold prismatic core/shell nanostructures of size around 30-50 nm and alloy like silver-gold prismatic nanoframes of size around 40-60 nm and investigated their plasmonic properties for the surface enhanced Raman spectroscopy (SERS) applications. Morphology and shape dependent plasmonic properties of these nanostructures were characterized by using high resolution transmission electron microscopy (HRTEM) and UV-Visible spectroscopy techniques respectively. The surface enhanced Raman spectroscopy (SERS) properties of all the fabricated nanostructures were investigated on Methylene Blue (MB) molecule. A gradual improvement in the SERS effect was observed with respect to the change of morphology from spherical to nanoframes and the order of SERS effect was found to be nanoframes > core/shell prismatic nanostructures > nanoprisms > spherical nanoparticles. Our investigation revealed that the phenomenon of the improved SERS effect of anisotropic silver and silver-gold nanostructures is primarily attributed to their prismatic geometrical configurations. PMID:24266213

Sakar, M; Parthiban, P; Balakumar, S

2013-12-01

284

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

285

Analysis of organic pollutant degradation in pulsed plasma by coherent anti-Stokes Raman spectroscopy  

SciTech Connect

The degradation of p-benzoquinone (p-BQ) in water was investigated by the coherent anti-Stokes Raman spectroscopy (CARS) method, in which the change of the anti-Stokes signal intensity corresponding to the vibrational transitions of the molecule is monitored during and after solution plasma processing (SPP). In the beginning of SPP treatment, the CARS signal intensity of the ring vibrational molecular transitions at 1233 and 1660 cm{sup -1} increases under the influence of the electric field of the plasma, depending on the delay time between the plasma pulse and the laser firing pulse. At the same time, the plasma contributes to the degradation of p-BQ molecules by generating hydrogen and hydroxyl radicals, which decompose p-BQ into different carboxylic acids. After SPP, the CARS signal intensity of the vibrational bands of p-BQ ceased and the degradation of p-BQ was confirmed by UV-visible absorption spectroscopy and liquid chromatography analysis.

Bratescu, Maria Antoneta; Hieda, Junko; Umemura, Tomonari; Saito, Nagahiro; Takai, Osamu [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2011-05-15

286

Quantitative Literacy  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards.On this wiki page, you will find online lessons, activities, and projects that allow students a range of real-world contexts. The Content Collections section contains sites that offer sets of problems and illustrations that connect middle school math to down-to-earth settings. The Interdisciplinary Lessons and Activities section offers activities and projects ready for interdisciplinary teaching. Each of the following sections focuses on a math topic: Data Analysis and Display, Probability, Measurement, Number and Operations. The resources offer mathematics in settings that deliberately cross over into other areas of the curriculum. Finally, for teachers looking for support in teaching quantitative literacy, a new approach for us all, Background Information for Teachers presents a select set of professional resources.

Herrera, Terese

2009-04-01

287

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

PubMed

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

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

2014-09-29

288

ZEKE Spectroscopy  

Microsoft Academic Search

Since 1984, ZEKE (ZEro Kinetic Energy) spectroscopy has matured into a very high resolution spectroscopy for the study of cations, anions, and indirectly through these species, neutrals--including very short lived intermediates in chemical rections. It has even yielded the first direct spectroscopic data on elusive transition states of chemical reactions. This is the first book to describe ZEKE spectroscopy, a

E. W. Schlag

1998-01-01

289

ZEKE Spectroscopy  

Microsoft Academic Search

Since 1984, ZEKE (ZEro Kinetic Energy) spectroscopy has matured into a very high resolution spectroscopy for the study of cations, anions, and indirectly through these species, neutrals--including very short lived intermediates in chemical rections. It has even yielded the first direct spectroscopic data on elusive transition states of chemical reactions. This is the first book to describe ZEKE spectroscopy, a

E. W. Schlag

2005-01-01

290

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

291

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

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

292

OPTICAL DESIGN AND PERFORMANCE OF THE ODIN UV/VISIBLE SPECTROGRAPH AND INFRARED IMAGER INSTRUMENT  

E-print Network

's mission will be both astronomy and atmospheric science (aeronomy). Its principle aeronomy payload Space Agency is funding this payload, which has the acronym "OSIRIS", and Routes Inc. is currently Odin in a circular sun-synchronous dawn/dusk orbit at approximately 600 kilometers altitude

Saskatchewan, University of

293

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

ERIC Educational Resources Information Center

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

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

2006-01-01

294

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

NASA Astrophysics Data System (ADS)

Solar UV and visible radiation scattered at the limb of the Earth's atmosphere is used for measuring density profiles of atmosperic trace gases. For example, the OSIRIS instrument on Odin and SCIAMACHY on Envisat use this technique. A limb-viewing instrument does not see Earth's surface or tropospheric clouds directly. However, in- direct light reflected from the surface or low altitude clouds can make up tens of per cents of the signal. Furthermore, the surface area that contributes to limb intensity ex- tends over 1000 km along the instrument line-of-sight and 200 km across it. Over this area surface reflectivity can vary from almost 0% to 100%. Inaccurate modelling of reflected intensity is a potential source of error in the trace gas retrieval. Generally, radiative transfer models used for analysing limb measure- ments have to assume that the surface has a constant albedo. We have used a three- dimensional Monte Carlo radiative transfer model to study the effects of surface vari- ation to limb radiance. Based on the simulations, we have developed an approximate method for averaging surface albedo for limb scattering measurements with the help of a simple single scattering radiative transfer model.

Oikarinen, L.

295

Transmission of UV/visible light through model human epidermis at varying ambient humidity  

NASA Astrophysics Data System (ADS)

Model human epidermal samples are used for transmission measurements at varying ambient humidity. Light is used from four different light emitting diodes (LEDs), of UVA wavelength of 365nm, and three visible wavelengths of 460nm, 500nm, and 595nm. A humidity-controlled chamber was used to house the samples while transmission measurements were taken. Many different types of measurements were taken, including raising ambient humidity from 20% to 75% then adding 0.5mL of water to the sample; lowering humidity from near 100% to 60%; and alternately raising and lowering of the ambient humidity. The results show higher transmission of light through the samples at very high ambient humidity, about 100%; whereas the transmission is much lower at lower ambient humidity. A simple model of epidermis as a turbid medium and reduced light scattering by refractive index matching is used to explain the results. Implications of these results are discussed.

Farley, Carlton W.; Sadate, Sandra; Kassu, Aschalew; Sharma, Anup

2014-09-01

296

Raman spectroscopy for noninvasive glucose measurements  

E-print Network

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

Enejder, Annika M. K.

297

Mossbauer Spectroscopy.  

ERIC Educational Resources Information Center

Reviews current research in Mossbauer spectroscopy, including instrumentation and experimental techniques, spectral analysis, catalysts and surfaces, environmental studies, medical applications and atmospheric air studies. Cites 346 references. (CS)

Stevens, John G.; Bowen, Lawrence H.

1980-01-01

298

Fundamentals of quantitative research  

Microsoft Academic Search

The main purpose of this article is to introduce some important fundamental concepts of quantitative research to readers especially novice researchers. It comprises types of research, definitions of quantitative research, different types and assumptions of quantitative research, when to use and not to use quantitative methods, advantages, common approaches and samples of quantitative research, and common misconceptions. Besides, a set

Suphat Sukamolson

299

Instrument Series: Spectroscopy and Diffraction XPS Imaging  

E-print Network

Instrument Series: Spectroscopy and Diffraction XPS Imaging The X-ray photoelectron spectroscopy (XPS) imaging system provides fast, quantitative, real-time parallel imaging with highest resolution and full-size glove box Ã? Automated Ar+ and cluster ion gun Enable angle-dependent XPS depth profile

300

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

E-print Network

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

Lau, Condon

301

Raman Spectroscopy.  

ERIC Educational Resources Information Center

Reviews literature on Raman spectroscopy from late 1981 to late 1983. Topic areas include: instrumentation and sampling; liquids and solutions; gases and matrix isolation; biological molecules; polymers; high-temperature and high-pressure studies; Raman microscopy; thin films and surfaces; resonance-enhanced and surface-enhanced spectroscopy; and…

Gerrard, Donald L.

1984-01-01

302

Role of trimer-trimer interaction of bacteriorhodopsin studied by optical spectroscopy and high-speed atomic force microscopy.  

PubMed

Bacteriorhodopsin (bR) trimers form a two-dimensional hexagonal lattice in the purple membrane of Halobacterium salinarum. However, the physiological significance of forming the lattice has long been elusive. Here, we study this issue by comparing properties of assembled and non-assembled bR trimers using directed mutagenesis, high-speed atomic force microscopy (HS-AFM), optical spectroscopy, and a proton pumping assay. First, we show that the bonds formed between W12 and F135 amino acid residues are responsible for trimer-trimer association that leads to lattice assembly; the lattice is completely disrupted in both W12I and F135I mutants. HS-AFM imaging reveals that both crystallized D96N and non-crystallized D96N/W12I mutants undergo a large conformational change (i.e., outward E-F loop displacement) upon light-activation. However, lattice disruption significantly reduces the rate of conformational change under continuous light illumination. Nevertheless, the quantum yield of M-state formation, measured by low-temperature UV-visible spectroscopy, and proton pumping efficiency are unaffected by lattice disruption. From these results, we conclude that trimer-trimer association plays essential roles in providing bound retinal with an appropriate environment to maintain its full photo-reactivity and in maintaining the natural photo-reaction pathway. PMID:23462099

Yamashita, Hayato; Inoue, Keiichi; Shibata, Mikihiro; Uchihashi, Takayuki; Sasaki, Jun; Kandori, Hideki; Ando, Toshio

2013-10-01

303

Laser-induced breakdown spectroscopy for light elements detection in steel: State of the art  

NASA Astrophysics Data System (ADS)

The development of a direct, rapid, and sensitive spectroscopic method for the analytical quantification of light (low atomic number) elements represents an important ongoing challenge. For the first time, we review the evolution of laser-induced breakdown spectroscopy (LIBS) technique for trace analysis of light elements in steels. We present studies carried out in both far/vacuum UV and UV-visible spectral regions, and focus on the elements carbon, sulfur, phosphorous, and nitrogen as their presence and content determine key properties of all steel products. In order to facilitate tracking down the evolution of the technique for a particular element/matrix, the review is organized in such a way that a chronological order has always been obeyed. Moreover, important information regarding characterization of a specific element in a given steel sample is tabulated, so that interested readers can easily locate relevant resources. Furthermore, typical examples of recent developments and advances in terms of LIBS instrumentation and systems regarding light elements in steels are summarized. Finally, the article suggests in brief some approaches for further raising the analytical capability and figures of merit of LIBS regarding trace compositional analysis of light elements. In this respect, we suggest combining LIBS with recently developed diode laser-based techniques such as DLIFS and DLAAS.

Khater, Mohamed A.

2013-03-01

304

Bimolecular photoinduced electron transfer reactions in liquids under the gaze of ultrafast spectroscopy.  

PubMed

Because of their key role in many areas of science and technology, bimolecular photoinduced electron transfer reactions have been intensively studied over the past five decades. Despite this, several important questions, such as the absence of the Marcus inverted region or the structure of the primary reaction product, have only recently been solved while others still remain unanswered. Ultrafast spectroscopy has proven to be extremely powerful to monitor the entire electron transfer process and to access, with the help of state-of-the-art theoretical models of diffusion-assisted reactions, crucial information like e.g. the intrinsic charge separation dynamics beyond the diffusion limit. Additionally, extension of these experimental techniques to other spectral regions than the UV-visible, such as the infrared, has given a totally new insight into the nature, the structure and the dynamics of the key reaction intermediates, like exciplexes and ions pairs. In this perspective, we highlight these recent progresses and discuss several aspects that still need to be addressed before a thorough understanding of these processes can be attained. PMID:25356933

Rosspeintner, Arnulf; Vauthey, Eric

2014-12-21

305

An application of ultraviolet spectroscopy to study interactions in proteins solutions at high concentrations.  

PubMed

Studies of protein-protein interactions (PPIs), especially in high-concentration solutions, have become increasingly important from a pharmaceutical perspective. Analytical methods used to study protein interactions, however, rely primarily on the detection of nonideality in relatively dilute (<50 mg/mL) solutions. We present here an application of variable-pathlength ultraviolet (UV)-visible absorption spectroscopy to examine and better understand such interactions over a wide concentration range (5-240 mg/mL) using several representative proteins. In this study, the change in UV absorption (or extinction coefficient) was monitored by determining delta absorbance (?Abs), the difference between the measured absorbance and the corresponding theoretical absorbance (calculated from gravimetric dilution), over a wide range of protein concentrations. The ?Abs, corrected for light scattering, was found to increase with protein concentration for three model proteins (bovine serum albumin, lysozyme, and monoclonal antibody). Because PPIs influence solution viscosity, we studied the correlation between ?Abs measurements and viscosity as a function of protein concentration. The magnitude of ?Abs and solution viscosity followed similar trends with increasing protein concentration, albeit to different extents for different proteins. These data support the use of such ?Abs measurements as an alternative approach to monitor and evaluate interactions in protein solutions at high concentration. PMID:22581726

Thakkar, Santosh V; Allegre, Kevin M; Joshi, Sangeeta B; Volkin, David B; Middaugh, C Russell

2012-09-01

306

Monitoring the in-situ oxide growth on uranium by ultraviolet-visible reflectance spectroscopy  

NASA Astrophysics Data System (ADS)

We demonstrate the in-situ monitoring of oxide growth on U-0.1 wt. % Cr by means of UV-visible reflectance spectroscopy in the thickness range of ˜20-150 nm. Two different approaches are presented: In the "modeling approach," we employ a model for a metallic substrate covered by a dielectric layer, while taking into account the buildup of oxygen gradient and surface roughness. Then, we fit the simulated spectra to the experimental one. In the "extrema analysis," we derive an approximated analytical expression, which relates the oxide thickness to the position of the extrema in the reflectance spectra based on the condition for optical interference of the reflected light. Good agreement is found between the values extracted by the two procedures. Activation energy of ˜21 kcal/mole was obtained by monitoring the oxide growth in the temperature range of 22-90 °C. The upper bound for the thickness determination is argued to be mostly dictated by cracking and detachment processes in the formed oxide.

Schweke, Danielle; Maimon, Chen; Chernia, Zelig; Livneh, Tsachi

2012-11-01

307

Vibrational and valence photoelectron spectroscopies, matrix photochemistry, and conformational studies of ClC(O)SSCl.  

PubMed

ClC(O)SSCl was prepared by an improved method by the reaction of [(CH(3))(2)CHOC(S)](2)S with SO(2)Cl(2) in hexane. The photoelectron spectra in the gas phase present four distinct regions, corresponding to ionizations from electrons formally located at the S, O, and Cl atoms and at the C?O bond. The vibrational IR and Raman spectra of the liquid were interpreted in terms of the most stable syn-gauche conformer (the O?C double bond syn with respect to the S-S single bond and the C-S single bond gauche with respect to the S-Cl single bond) in equilibrium with the less stable anti-gauche form, both occurring in two enantiomeric forms. The randomization process between the conformers was induced by broad-band UV-visible irradiation in matrix conditions, and several photoproducts were identified by FTIR spectroscopy. The experimental results were complemented by theoretical calculations. PMID:21827200

Tobón, Yeny A; Cozzarín, Melina V; Wang, Wei-Gang; Ge, Mao-Fa; Della Védova, Carlos O; Romano, Rosana M

2011-09-15

308

Copper Complexes Stabilized by Chitosans: Peculiarities of the Structure, Redox, and Catalytic Properties  

Microsoft Academic Search

Peculiarities of the structure and physicochemical properties of copper–chitosan complexes prepared by different methods were studied by IR, UV-visible, ESR spectroscopy, and electron microscopy. The catalytic activity of redox copper centers stabilized by the chitosan matrix in the reactions of oxidation of o- and p-dihydroxybenzenes in an aqueous medium was determined. Quantitative ESR measurements provide evidence for the localization of

N. V. Kramareva; E. D. Finashina; A. V. Kucherov; L. M. Kustov

2003-01-01

309

Effect of particle size distributions on absorbance spectra of gold nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, a method is developed to calculate the absorbance spectra of nanoparticles solution containing a size distribution of particles using the Mie theory. The standard gold nanoparticles solutions were purchased and characterized with the UV-visible absorption spectroscopy and dynamic light scattering size measurements techniques. Model size distributions were fit to the experimental absorbance spectra using the method described herein. Good semi-quantitative fits were found, which elucidate qualitative differences between “small” and “large” gold nanoparticles.

Doak, J.; Gupta, R. K.; Manivannan, K.; Ghosh, K.; Kahol, P. K.

2010-03-01

310

Rapid biological synthesis of silver nanoparticles using plant leaf extracts  

Microsoft Academic Search

Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis\\u000a of metallic silver nanoparticles. Stable silver nanoparticles were formed by treating aqueous solution of AgNO3 with the plant leaf extracts as reducing agent of Ag+ to Ag0. UV-visible spectroscopy was used to monitor the quantitative formation of silver nanoparticles. Magnolia leaf broth

Jae Yong Song; Beom Soo Kim

2009-01-01

311

XPS, UV-vis spectroscopy and AFM studies on removal mechanisms of Si-face SiC wafer chemical mechanical polishing (CMP)  

NASA Astrophysics Data System (ADS)

Chemical mechanical polishing (CMP) removal mechanisms of on-axis Si-face SiC wafer have been investigated through X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) spectroscopy and atomic force microscopy (AFM). XPS results indicate that silicon oxide is formed on Si-face surface polished by the slurry including oxidant H2O2, but not that after immersing in H2O2 solution. UV-vis spectroscopy curves prove that •OH hydroxyl radical could be generated only under CMP polishing by the slurry including H2O2 and abrasive, so as to promote oxidation of Si-face to realize the effective removal; meanwhile, alkali KOH during CMP could induce the production of more radicals to improve the removal. On the other side, ultra-smooth polished surface with atomic step structure morphology and extremely low Ra of about 0.06 nm (through AFM) is obtained using the developed slurry with silica nanoparticle abrasive. Through investigating the variations of the atomic step morphology on the surface polished by different slurries, it's reveals that CMP removal mechanism involves a simultaneous process of surface chemical reaction and nanoparticle atomic scale abrasion.

Zhou, Yan; Pan, Guoshun; Shi, Xiaolei; Xu, Li; Zou, Chunli; Gong, Hua; Luo, Guihai

2014-10-01

312

Synthesis, crystal structure, vibrational spectroscopy, optical properties and theoretical studies of a new organic-inorganic hybrid material: [((CH3)2NH2)(+)]6·[(BiBr6)(3-)]2.  

PubMed

A new organic-inorganic hybrid material, [((CH3)2NH2)(+)]6·[(BiBr6)(3-)]2, has been synthesized and characterized by X-ray diffraction, FT-IR, Raman spectroscopy and UV-Visible absorption. The studied compound crystallizes in the triclinic system, space group P1¯ with the following parameters: a=8.4749(6)(?), b=17.1392(12)(?), c=17.1392(12)(?), ?=117.339(0)°, ?=99.487(0)°, ?=99.487(0)° and Z=2. The crystal lattice is composed of a two discrete (BiBr6)(3-) anions surrounded by six ((CH3)2NH2)(+) cations. Complex hydrogen bonding interactions between (BiBr6)(3-) and organic cations from a three-dimensional network. Theoretical calculations were performed using density functional theory (DFT) for studying the molecular structure, vibrational spectra and optical properties of the investigated molecule in the ground state. The full geometry optimization of designed system is performed using DFT method at B3LYP/LanL2DZ level of theory using the Gaussian03. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from FT-IR and Raman spectra are assigned based on the results of the theoretical calculations. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental UV-Visible spectrum. The results show good consistent with the experiment and confirm the contribution of metal orbital to the HOMO-LUMO boundary. PMID:24967541

Ben Ahmed, A; Feki, H; Abid, Y

2014-12-10

313

Moessbauer spectroscopy  

SciTech Connect

This review on Moessbauer spectroscopy is based on the papers that have been received and surveyed by the Moessbauer Effect Data Center since our 1984 review (257), and therefore, the papers included in this review are from the period 1983-1985. During the last 2 years a total of over 2000 papers on Moessbauer spectroscopy were processed by the data center. From these 2000+ papers approximately 300 were selected to be discussed in this review. Despite the flaws in the process of selection, the review represents a good summary of what has been happening in the field of Moessbauer spectroscopy during the last 2 years. 302 references.

Stevens, J.G.; Bowen, L.H.; Whatley, K.M.

1986-04-01

314

Amateur Spectroscopy  

NSDL National Science Digital Library

The main objective of this website is to teach the amateur astronomer how to perform spectroscopy. The first part of the website is dedicated to establishing a theoretical foundation, in which the process of spectroscopy is explained: how spectral lines are created, the operation of a spectroscope, and grating spectroscopy. Later on, all these concepts are applied to astronomy, specifically to stars. Using spectroscopy, astronomers are able to identify the composition of stars, which leads to a classification catalog dependent on the spectral lines observed. Several spectra, from different objects like supernovae and stars are presented for the user to observe, along with distinctive spectral lines from some chemical elements. Finally, this website motivates amateurs by suggesting several project ideas along with a list of references and instrument suppliers.

2010-05-06

315

NMR Spectroscopy  

NSDL National Science Digital Library

Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts. These questions pertain to Nuclear magnetic resonance (NMR) spectroscopy and include topics such as: Chemical Shift, Proton NMR, and Carbon NMR.

Reich, Ieva

2008-03-25

316

ZEKE Spectroscopy  

NASA Astrophysics Data System (ADS)

Since 1984, ZEKE (ZEro Kinetic Energy) spectroscopy has matured into a very high resolution spectroscopy for the study of cations, anions, and indirectly through these species, neutrals--including very short lived intermediates in chemical rections. It has even yielded the first direct spectroscopic data on elusive transition states of chemical reactions. This is the first book to describe ZEKE spectroscopy, a new high resolution spectroscopy of molecular ions, neutral short-lived intermediates, and other species. The author's approach is to use a minimum of equations and large numbers of figures to help the reader toward a basic understanding of the many unique concepts of this new form of spectroscopy and the new spectroscopic information that it provides. This book will be of interest to anyone interested in the spectroscopy of ions or neutrals, particularly short-lived neutrals, formed from these ions. It should also be of interest to reaction kineticists interested in the study of reactions involving such highly state selected species.

Schlag, E. W.

1998-06-01

317

ZEKE Spectroscopy  

NASA Astrophysics Data System (ADS)

Since 1984, ZEKE (ZEro Kinetic Energy) spectroscopy has matured into a very high resolution spectroscopy for the study of cations, anions, and indirectly through these species, neutrals--including very short lived intermediates in chemical rections. It has even yielded the first direct spectroscopic data on elusive transition states of chemical reactions. This is the first book to describe ZEKE spectroscopy, a new high resolution spectroscopy of molecular ions, neutral short-lived intermediates, and other species. The author's approach is to use a minimum of equations and large numbers of figures to help the reader toward a basic understanding of the many unique concepts of this new form of spectroscopy and the new spectroscopic information that it provides. This book will be of interest to anyone interested in the spectroscopy of ions or neutrals, particularly short-lived neutrals, formed from these ions. It should also be of interest to reaction kineticists interested in the study of reactions involving such highly state selected species.

Schlag, E. W.

2005-07-01

318

Quantitation of carcinogen bound protein adducts by fluorescence measurements  

NASA Astrophysics Data System (ADS)

A highly significant correlation of aflatoxin B 1 serum albumin adduct level with daily aflatoxin B 1 intake was observed in a molecular epidemiological study of aflatoxin carcinogenesis which used conventional fluorescence spectroscopy methods for adduct quantitation. Synchronous fluorescence spectroscopy and laser induced fluorescence techniques have been employed to quantitate antibenzo[ a]pyrene diol epoxide derived globin peptide adducts. Fast and efficient methods to isolate the peptide adducts as well as eliminate protein fluorescence background are described. A detection limit of several femtomoles has been achieved. Experimental and technical considerations of low temperature synchronous fluorescence spectroscopy and fluorescence line narrowing to improve the detection sensitivities are also presented.

Gan, Liang-Shang; Otteson, Michael S.; Doxtader, Mark M.; Skipper, Paul L.; Dasari, Ramachandra R.; Tannenbaum, Steven R.

1989-01-01

319

Pb-207 NMR Spectroscopy Reveals that Pb(II) Coordinates with Glutathione (GSH) and Tris Cysteine Zinc Finger Proteins in a PbS3 Coordination Environment  

PubMed Central

207Pb NMR spectroscopy can be used to monitor the binding of Pb(II) to thiol rich biological small molecules such as glutathione and to zinc finger proteins. The UV/visible (UV/Vis) absorption band centered at 334 nM and the observed 207Pb-signal in 207Pb NMR (? ~ 5750 ppm) indicate that glutathione binds Pb(II) in a trigonal pyramidal geometry (PbS3) at pH 7.5 or higher with a 1:3 molar ratio of Pb(II) to GSH. While previous studies using UV/Vis and extended X-ray absorption fine structure (EXAFS) spectroscopy were interpreted to show that the zinc binding domain from HIV nucleocapsid protein (HIV-CCHC) binds Pb(II) in a single PbS3 environment, the more sensitive 207Pb NMR spectra (at pH 7.0, 1:1 molar ratio) provide compelling evidence for the presence of two PbS3 structures (? = 5790 and 5744 ppm), one of which is more stable at high temperatures. It has previously been proposed that the HIV-CCHH peptide does not fold properly to afford a PbS2N motif, because histidine does not bind to Pb(II). These predictions are confirmed by the present studies. These results demonstrate the applicability of 207Pb NMR to biomolecular structure determination in proteins with cysteine binding sites for the first time. PMID:21625408

Neupane, Kosh P.; Pecoraro, Vincent L.

2011-01-01

320

Infrared Spectroscopy  

NSDL National Science Digital Library

This 38-page PDF document is a chapter from the Handbook of Instrumental Techniques for Analytical Chemistry. The chapter explains how infrared spectroscopy works (no comma) along with its general uses, common applications, range and limitations. Also included are spectrometer designs, information about sample preparation, analytical methods, related methods such as gas chromotography and diffuse reflectance, and costs and instrument vendors.

Hsu, C. P.; Hall, Prentice

321

LED Spectroscopy  

NSDL National Science Digital Library

This resource, part of the Spectroscopy Lab Suite, simulates optical transitions in solids. Emission spectra from different color Light Emitting Diodes are shown. Students can create conduction and valence bands, and electronic transitions, to match the observed spectra of the diodes. The energy and width of the bands can be modified.

Group, Kansas S.; Zollman, Dean A.

2004-03-05

322

Hydrogen Spectroscopy  

NSDL National Science Digital Library

This tutorial covers the topics of spectra and spectroscopy, focusing on the hydrogen atom. Questions are provided for students to explore the material, and interactive simulations are used for interactive investigations. This resource is a part of the Visual Quantum Mechanics project.

Group, Kansas S.; Zollman, Dean A.

2004-03-10

323

Blood analysis by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r2 values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

Enejder, Annika M. K.; Koo, Tae-Woong; Oh, Jeankun; Hunter, Martin; Sasic, Slobodan; Feld, Michael S.; Horowitz, Gary L.

2002-11-01

324

Study on the binding of chloroamphenicol with bovine serum albumin by fluorescence and UV-vis spectroscopy  

NASA Astrophysics Data System (ADS)

The binding of chloroamphenicol (CPC) to bovine serum albumin (BSA) at 296 K, 303 K, and 310 K by fluorescence and UV-visible absorption spectroscopy were investigated under imitated physiological conditions. The experimental results showed that the fluorescence quenching mechanism between CPC and BSA was combined quenching (dynamic and static quenching) procedure at low CPC concentration, or a dynamic quenching procedure at high concentrations. The binding constants, binding sites and the corresponding thermodynamic parameters of the interaction system were calculated. According to Förster non-radiation energy transfer theory, the binding distance between CPC and BSA was calculated to be 3.02 nm. Both synchronous fluorescence and FT-IR spectra confirmed the interaction, and indicated the conformational changes of BSA. The effects of some common metal ions Ca2+, Ni2+, Mg2+, Fe2+, and Cu2+ on the binding constant between CPC and BSA were examined. Furthermore, we investigated the possible sub-domains on BSA that bind CPC by displacement experiments.

Zhang, Jun; Chen, Lingnan; Zeng, Birong; Kang, Qilong; Dai, Lizong

2013-03-01

325

Cultural heritage and archaeology materials studied by synchrotron spectroscopy and imaging  

NASA Astrophysics Data System (ADS)

The use of synchrotron radiation techniques to study cultural heritage and archaeological materials has undergone a steep increase over the past 10-15 years. The range of materials studied is very broad and encompasses painting materials, stone, glass, ceramics, metals, cellulosic and wooden materials, and a cluster of organic-based materials, in phase with the diversity observed at archaeological sites, museums, historical buildings, etc. Main areas of investigation are: (1) the study of the alteration and corrosion processes, for which the unique non-destructive speciation capabilities of X-ray absorption have proved very beneficial, (2) the understanding of the technologies and identification of the raw materials used to produce archaeological artefacts and art objects and, to a lesser extent, (3) the investigation of current or novel stabilisation, conservation and restoration practices. In terms of the synchrotron methods used, the main focus so far has been on X-ray techniques, primarily X-ray fluorescence, absorption and diffraction, and Fourier-transform infrared spectroscopy. We review here the use of these techniques from recent works published in the field demonstrating the breadth of applications and future potential offered by third generation synchrotron techniques. New developments in imaging and advanced spectroscopy, included in the UV/visible and IR ranges, could even broaden the variety of materials studied, in particular by fostering more studies on organic and complex organic-inorganic mixtures, while new support activities at synchrotron facilities might facilitate transfer of knowledge between synchrotron specialists and users from archaeology and cultural heritage sciences.

Bertrand, Loïc; Robinet, Laurianne; Thoury, Mathieu; Janssens, Koen; Cohen, Serge X.; Schöder, Sebastian

2012-02-01

326

A unique charge-coupled device/xenon arc lamp based imaging system for the accurate detection and quantitation of multicolour fluorescence.  

PubMed

In recent years the use of fluorescent dyes in biological applications has dramatically increased. The continual improvement in the capabilities of these fluorescent dyes demands increasingly sensitive detection systems that provide accurate quantitation over a wide linear dynamic range. In the field of proteomics, the detection, quantitation and identification of very low abundance proteins are of extreme importance in understanding cellular processes. Therefore, the instrumentation used to acquire an image of such samples, for spot picking and identification by mass spectrometry, must be sensitive enough to be able, not only, to maximise the sensitivity and dynamic range of the staining dyes but, as importantly, adapt to the ever changing portfolio of fluorescent dyes as they become available. Just as the available fluorescent probes are improving and evolving so are the users application requirements. Therefore, the instrumentation chosen must be flexible to address and adapt to those changing needs. As a result, a highly competitive market for the supply and production of such dyes and the instrumentation for their detection and quantitation have emerged. The instrumentation currently available is based on either laser/photomultiplier tube (PMT) scanning or lamp/charge-coupled device (CCD) based mechanisms. This review briefly discusses the advantages and disadvantages of both System types for fluorescence imaging, gives a technical overview of CCD technology and describes in detail a unique xenon/are lamp CCD based instrument, from PerkinElmer Life Sciences. The Wallac-1442 ARTHUR is unique in its ability to scan both large areas at high resolution and give accurate selectable excitation over the whole of the UV/visible range. It operates by filtering both the excitation and emission wavelengths, providing optimal and accurate measurement and quantitation of virtually any available dye and allows excellent spectral resolution between different fluorophores. This flexibility and excitation accuracy is key to multicolour applications and future adaptation of the instrument to address the application requirements and newly emerging dyes. PMID:11332749

Spibey, C A; Jackson, P; Herick, K

2001-03-01

327

Anatomy-Based Algorithms for Detecting Oral Cancer Using Reflectance and Fluorescence Spectroscopy  

E-print Network

OBJECTIVES: We used reflectance and fluorescence spectroscopy to noninvasively and quantitatively distinguish benign from dysplastic/malignant oral lesions. We designed diagnostic algorithms to account for differences in ...

McGee, Sasha

328

Grain Spectroscopy  

NASA Technical Reports Server (NTRS)

Our fundamental knowledge of interstellar grain composition has grown substantially during the past two decades thanks to significant advances in two areas: astronomical infrared spectroscopy and laboratory astrophysics. The opening of the mid-infrared, the spectral range from 4000-400 cm(sup -1) (2.5-25 microns), to spectroscopic study has been critical to this progress because spectroscopy in this region reveals more about a materials molecular composition and structure than any other physical property. Infrared spectra which are diagnostic of interstellar grain composition fall into two categories: absorption spectra of the dense and diffuse interstellar media, and emission spectra from UV-Vis rich dusty regions. The former will be presented in some detail, with the latter only very briefly mentioned. This paper summarized what we have learned from these spectra and presents 'doorway' references into the literature. Detailed reviews of many aspects of interstellar dust are given.

Allamandola, L. J.

1992-01-01

329

Moessbauer Spectroscopy  

SciTech Connect

The first review of Moessbauer spectroscopy that appeared as part of the Analytical Chemistry fundamental review was published in 1966 making the current review the 12th in the series. The last nine of these have used the facilities of the Moessbauer Effect Data Center. Papers that are included in the current review are those papers that have been received and surveyed by the data center since the last review. Papers that are included in the review are mostly from 1985-1987. During the last two years approximately 2500 papers on Moessbauer spectroscopy have been processed by the data center. It is from this compilation of 2500 papers that approximately 300 papers were selected to be in this review. The process for identifying the papers to be used in the review is most difficult. Certainly, the selection process leans toward the individual interests of the three of them. But despite this difficulty, the review represents a good summary of what has been happening in the field of Moessbauer spectroscopy during the past two years.

Stevens, J.G.; Bowen, L.H.; Whatley, K.M.

1988-06-15

330

Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

Anderson localization of matter-waves in a controlled disorder: a quantum simulator? / A. Aspect ... [et al.] -- Squeezing and entanglement in a Bose-Einstein condensate / C. Gross ... [et al.] -- New physics in dipolar Bose-Einstein condensates / Y. Kawaguchi, H. Saito, and M. Ueda -- Observation of vacuum fluctuations in a spinor Bose-Einstein condensate / C. Klempt ... [et al.] -- Negative-index media for matter waves / F. Perales ... [et al.] -- Entanglement of two individual atoms using the Rydberg blockade / A. Browaeys ... [et al.] -- Array of mesoscopic ensembles on a magnetic atom chip / A. F. Tauschinsky ... [et al.] -- Stability of the proton-to-electron mass ratio tested with molecules using an optical link to primary clock / A. Amy-Klein ... [et al.] -- Metastable helium: lifetime measurements using cold atoms as a test of QED / K. G. H. Baldwin ... [et al.] -- Optical lattice clocks with single occupancy bosons and spin-polarized fermions toward 10[symbol] accuracy / M. Takamoto ... [et al.] -- Frequency measurements of Al[symbol] and Hg[symbol] optical standards / W. M. Itano ... [et al.] -- Switching of light with light using cold atoms inside a hollow optical fiber / M. Bajcsy ... [et al.] -- Room-temperature atomic ensembles for quantum memory and magnetometry / K. Jensen ... [et al.] -- Components for multi-photon non-classical state preparation and measurement / G. Puentes ... [et al.] -- Quantum field state measurement and reconstruction in a cavity by quantum nondemolition photon counting / M. Brune ... [et al.] -- XUV frequency comb spectroscopy / C. Gohle ... [et al.] -- Ultrahigh-repetition-rate pulse train with absolute-phase control produced by an adiabatic raman process / M. Katsuragawa ... [et al.] -- Strongly correlated bosons and fermions in optical lattices / S. Will ... [et al.] -- Bragg spectroscopy of ultracold bose gases in optical lattices / L. Fallani ... [et al.] -- Synthetic quantum many-body systems / C. Guerlin ... [et al.] -- Ultracold Ytterbium atoms in optical lattices / S. Sugawa ... [et al.] -- Ultracold polar molecules in the rovibrational ground state / J. Deiglmayr ... [et al.] -- Polar molecules near quantum degeneracy / J. Ye and D. S. Jin -- Production of a quantum gas of rovibronic ground-state molecules in an optical lattice / J. G. Danzl ... [et al.] -- Recent progress in x-ray nonlinear optics / K. Tamasaku, K. Sawada, and T. Ishikawa -- Gas in scattering media absorption spectroscopy - laser spectroscopy in unconventional environments / S. Svanberg -- Laser spectroscopy on relativistic ion beams / S. Reinhardt ... [et al.] -- Single frequency microcavity lasers and applications / L. Xu ... [et al.].

Katori, H.; Yoneda, H.; Nakagawa, K.; Shimizu, F.

2010-02-01

331

Exploring Higgs Sector Spectroscopy  

E-print Network

The Higgs sector of the standard model is field-theoretically a very interesting theory. Because strong and weak coupling domains are continuously connected, only quantitative changes distinguish the various regions. Especially, this is true for the asymptotic spectrum, which can only consist out of gauge-invariant composite, i. e. bound, states. Since in some regions of parameter space even Regge trajectories are expected to exist, there is immediately the possibility that resonances may also be present in the parameter region characteristic of the standard model Higgs sector. This possibility is discussed in some detail, starting from the definition of the theory to spectroscopy, including excited state analysis, to some considerations whether this could have experimental consequences. The strongest limitation for this exploration turns out to be that the gauge coupling without fermions runs much faster, and the gauge sector is therefore potentially affected.

Axel Maas; Tajdar Mufti

2013-10-29

332

Quantitative Measurements of HO2 and Other Products of n-Butane Oxidation (H2O2, H2O, CH2O, and C2H4) at Elevated Temperatures by Direct Coupling of a Jet-Stirred Reactor with Sampling Nozzle and Cavity Ring-Down Spectroscopy (cw-CRDS).  

PubMed

For the first time quantitative measurements of the hydroperoxyl radical (HO2) in a jet-stirred reactor were performed thanks to a new experimental setup involving fast sampling and near-infrared cavity ring-down spectroscopy at low pressure. The experiments were performed at atmospheric pressure and over a range of temperatures (550-900 K) with n-butane, the simplest hydrocarbon fuel exhibiting cool flame oxidation chemistry which represents a key process for the auto-ignition in internal combustion engines. The same technique was also used to measure H2O2, H2O, CH2O, and C2H4 under the same conditions. This new setup brings new scientific horizons for characterizing complex reactive systems at elevated temperatures. Measuring HO2 formation from hydrocarbon oxidation is extremely important in determining the propensity of a fuel to follow chain-termination pathways from R + O2 compared to chain branching (leading to OH), helping to constrain and better validate detailed chemical kinetics models. PMID:25381864

Djehiche, Mokhtar; Le Tan, Ngoc Linh; Jain, Chaithanya D; Dayma, Guillaume; Dagaut, Philippe; Chauveau, Christian; Pillier, Laure; Tomas, Alexandre

2014-11-26

333

Early diagnosis of cancer using light scattering spectroscopy  

E-print Network

This thesis presents a novel optical technique, light scattering spectroscopy (LSS), developed for quantitative characterization of tissue morphology as well as in vivo detection and diagnosis of the diseases associated ...

Backman, Vadim, 1973-

2001-01-01

334

Solid-State NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

Due to the development of new techniques and further increase of magnetic field strength available for commercial applications, solid-state NMR spectroscopy became a routine method for the characterization of zeolites. As an important advantage, solid-state NMR spectroscopy allows the investigation of the local structure of nuclei in the solids under study. The specific behavior of zeolites often depends on local effects, such as framework defects, the substitution of framework atoms, guest compounds etc. Therefore, solid-state NMR spectroscopy is a widely applied analytical method for delivering structure data, which are complementary to those of diffraction methods suitable for investigating the long-range order. While early solid-state NMR spectroscopic studies often focused on the characterization of the zeolite framework in the as-synthesized and hydrated state, an increasing number of recent works is dealing with the investigation of the framework of dehydrated and calcined zeolites and of surface sites, i.e., on the determination of their concentration, strength, and accessibility. In all these applications, the advantage of solid-state NMR spectroscopy to be a quantitative method is utilized. The present chapter demonstrates the fundamentals, various techniques, and most important applications of solid-state NMR spectroscopy making this method to an important tool of research in zeolite science.

Hunger, Michael

335

Renaissance in diatomic spectroscopy  

NASA Astrophysics Data System (ADS)

New technological developments resulted in several periods of renaissances of spectroscopy, the period on microwaves and later the period with lasers, and led to developments of new models for description of observations, thus to understanding the underlying physics. Today, the exciting period of cold molecules has started and demands for new data from molecular spectroscopy and completion in their modeling. This contribution will describe the status of understanding before the era of "cold molecules" and note open questions when entering the field of cold molecules. Because large varieties of cold molecules are studied, like deeply bound (about 1eV) or very weakly bound (less than 10-7 eV) ones, the spectroscopic tools and the theoretical descriptions have to be largely extended. We will describe recent success regarding different molecules of diatomic alkaliand alkaline-earth atoms as examples and will show how to use the often huge body of spectroscopic data for obtaining predictions for optimal paths to produce ultra cold molecules in a desired molecular state. It is very exciting to combine the results of spectroscopy and of studies of ultra cold ensembles which are influenced by their atom-to-molecule changeover. This allows already to complete the understanding of the electronic structure of atom pairs from infinite internuclear separation down to the range of strongly overlapping electronic distribution in some cases (e.g. KRb or KCs). However, enhanced effort is required for describing quantitatively the discoveries, already published or expected, like a contribution to the field hunting for signatures of time dependence of fundamental constants. For molecules with their rotational and vibrational motion the ratio of electron mass-to-nuclear mass as a fundamental constant shows up as an obvious attraction for spectroscopic studies.

Tiemann, Eberhard; Knöckel, Horst

2013-07-01

336

Quantitative nuclear hepatology  

SciTech Connect

This is the first in a series of four Continuing Education articles on quantitative imaging techniques. After studying this article, the reader should be able to: 1) compare the radiopharmaceuticals available for hepatobiliary imaging; 2) discuss quantitation of hepatobiliary studies; and 3) discuss the clinical applications of these techniques.

Gilbert, S.A.; Brown, P.H.; Krishnamurthy, G.T.

1987-03-01

337

Modern quantitative schlieren techniques  

Microsoft Academic Search

Schlieren optical techniques have traditionally been used to qualitatively visualize refractive flowfields in transparent media. Modern schlieren optics, however, are increasingly focused on obtaining quantitative information such as temperature and density fields in a flow -- once the sole purview of interferometry -- without the need for coherent illumination. Quantitative data are obtained from schlieren images by integrating the measured

Michael Hargather; Gary Settles

2010-01-01

338

Journal of Quantitative Spectroscopy & Radiative Transfer 98 (2006) 189201  

E-print Network

or days later after the accident. Damages in the secondary phase are due to the disorientation of body currently available to scan for the extent of brain damages before and after surgeries. The most common ones. E-mail address: guo@jove.rutgers.edu (Z. Guo). #12;pool in the upper body due to the microgravity

Guo, Zhixiong "James"

339

Journal of Quantitative Spectroscopy & Radiative Transfer 109 (2008) 458467  

E-print Network

was modeled using the HITRAN04 database and a Van Vleck­Weisskopf lineshape function with a 100 cm�1 far applications [1]. In many regions, the water vapor absorption spectrum strongly contributes to the baseline characterized by a database (consisting of frequencies, intensities, and shape parameters for individual lines

340

Quantitative Rapid Scan EPR Spectroscopy at 258 MHz  

PubMed Central

Experimental data obtained with an electron paramagnetic resonance (EPR) rapid scan spectrometer were translated through the reverse transfer functions of the spectrometer hardware to the sample position. Separately, theoretical calculations were performed to predict signal and noise amplitudes at the sample position for specified experimental conditions. A comparison was then made between the translated experimental values and the calculated values. Excellent agreement was obtained. PMID:20382055

Quine, Richard W.; Rinard, George A.; Eaton, Sandra S.; Eaton, Gareth R.

2011-01-01

341

Journal of Quantitative Spectroscopy & Radiative Transfer 109 (2008) 14471460  

E-print Network

-1197, USA c Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy in English. This excludes a few papers published in Russian and a substantial number of papers published approach that we have adopted. We plan to maintain an updated version of the combined database on the web

342

Reflectance Spectroscopy: Quantitative Analysis Techniques for Remote Sensing Applications  

Microsoft Academic Search

Several methods for the analysis of remotely sensed reflectance data are compared, including empirical methods and scattering theories, both of which are important for solving remote sensing problems. The concept of the photon mean optical path length and the implications for use in modeling reflectance spectra are presented. It is shown that the mean optical path length in a particulate

Roger N. Clark; Ted L. Roush

1984-01-01

343

Journal of Quantitative Spectroscopy & Radiative Transfer 105 (2007) 243263  

E-print Network

assimilation algorithms based on hyperspectral measurements, a RT model must be computationally efficient radiative transfer model based on the adding­doubling method for hyperspectral remote-sensing applications-AD, to facilitate the forward RT simulations involved in hyperspectral remote-sensing applications under cloudy

Li, Jun

344

Journal of Quantitative Spectroscopy & Radiative Transfer 100 (2006) 457469  

E-print Network

in the near- infrared spectrum to the particle effective size increases with the increase of the incident for the sensitivity of the bidirectional reflectance to particle size, particularly, at a near-infrared wavelength. r at visible wavelengths; additionally, snow also significantly absorbs near-infrared radiation. Because of its

345

Quantitative characterization of tissue microstructure with temporal diffusion spectroscopy q  

E-print Network

t The signals recorded by diffusion-weighted magnetic resonance imaging (DWI) are dependent on the micro the behavior of water diffusion over different time scales and the potential to detect variations measurements that can be used for applications such as monitoring tumor response to treatment in vivo. Ã? 2009

Xu, Junzhong

346

Journal of Quantitative Spectroscopy & Radiative Transfer 101 (2006) 556  

E-print Network

theory. This excellent monograph describes the fundamentals of the theory of polarized light transfer in planetary atmospheres and other sparse particulate media in a systematic, clear, and concise way. Basic with a summary of the single-scattering theory followed by a detailed account of the vector radiative transfer

347

Journal of Quantitative Spectroscopy & Radiative Transfer 105 (2007) 356  

E-print Network

by random arrangements of scatterers and does not include the theory of radiative transfer and coherent backscattering by particulate media. However, covering these vast subjects would require a separate volume

348

Journal of Quantitative Spectroscopy & Radiative Transfer 106 (2007) 616621  

E-print Network

localization of electromagnetic waves can survive even in densely packed particulate media. Published measurements of WL for dilute particle suspensions and allows one to use the microphysical theory of WL valid). #12;closely related to the microphysical theory of radiative transfer [7­10]. However, the criteria

349

Journal of Quantitative Spectroscopy & Radiative Transfer 93 (2005) 231243  

E-print Network

analyses are made of the shifts of resonance frequencies of whispering-gallery-mode (WGM) for a fiber). #12;1. Introduction In recent years, the advances in micro/nano-fabrication techniques have made of the evanescent radiation field of WGMs with the evanescent field of a phase-matched optical fiber or waveguide

Guo, Zhixiong "James"

350

Clinical feasibility of Raman spectroscopy for quantitative blood glucose measurement  

E-print Network

Diabetes mellitus is a leading cause of morbidity and mortality worldwide, and close monitoring of blood glucose levels is crucial for its diagnosis and management. Currently, blood glucose monitoring is done by blood ...

Kong, Chae-Ryon

2011-01-01

351

Power-dependent line-shape corrections for quantitative spectroscopy  

NASA Astrophysics Data System (ADS)

The Voigt profile—a convolution of a Gaussian and a Lorentzian—accurately describes the absorption lines of atomic and molecular gases at low probe powers. Fitting experimental absorption data to such a Voigt profile yields both the Lorentzian natural linewidth and the Gaussian Doppler broadening. However, as the probe power increases, saturation effects change the absorption line shape, such that it is no longer accurately described by a Voigt profile. Naively fitting a simple Voigt profile to the absorption line therefore introduces spurious power dependence into the extracted Doppler component. Using a simple atomic model, we calculate power-dependent corrections to the Voigt profile, which are parametrized by the Gaussian Doppler width, the Lorentzian natural linewidth, and the optical depth. We show numerically and experimentally that including the correction term substantially reduces the spurious power dependence in the fitted Gaussian width.

Stace, Thomas M.; Truong, Gar-Wing; Anstie, James; May, Eric F.; Luiten, André N.

2012-07-01

352

Investigation of the azo-hydrazone tautomeric equilibrium in an azo dye involving the naphthalene moiety by UV-vis spectroscopy and quantum chemistry  

NASA Astrophysics Data System (ADS)

Photophysical properties of the azo-hydrazone tautomerism of Eriochrome Blue Black B (1-(1-hydroxy-2-naphthylazo)-2-naphthol-4-sulphonic acid) in DMF, MeCN and water were investigated using UV-visible spectroscopy and quantum chemical calculations. The optimized molecular structure parameters, relative energies, mole fractions, electronic absorption spectra and HOMO-LUMO energies for possible stable tautomeric forms of EBB were theoretically calculated by using hybrid density functional theory, (B3LYP) methods with 6-31G(d) basis set level and polarizable continuum model (PCM) for solvation effect. The effects of varying pH-, dye concentration-, solvent-, temperature-, and time-dependences on the UV-vis spectra of Eriochrome Blue Black B were also investigated experimentally. The calculations showed that the dye exhibited acid-base, azo-hydrazone and aggregate equilibria in DMF solution, while the most probably preferred form in MeCN solution was azo form. Thermodynamic parameters of dimerization reaction in DMF solution proved that entropy was the driving force of this reaction.

Ünal, Arslan; Eren, Bilge; Eren, Erdal

2013-10-01

353

Synthesis, X-ray crystal structure and spectroscopy of a Werner-type host Co(II) complex, trans-bisisothiocyanatotetrakis( trans-4-styrylpyridine)cobalt(II)  

NASA Astrophysics Data System (ADS)

Single crystals of the title Co(II) complex, [Co(stpy) 4(NCS) 2] [stpy= trans-4-styrylpyridine] are prepared and characterized by elemental analysis, IR, and UV-visible spectroscopy and X-ray crystal structure determination. The complex crystallizes in the orthorhombic space group Pna2 1 with unit-cell parameters, a=32.058(3), b=15.362(5), c=9.818(5) Å, and Z=4. The structure consists of discrete monomeric units of [Co(stpy) 4(NCS) 2]. The equatorial positions of the Co(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions are occupied by the nitrogen atoms of the two thiocyanate ions. The unit cell packing reveals interpenetration of styryl groups owing to conformational flexibility of phenyl and pyridyl rings in stpy ligands. Thus, it leads to efficient packing of the crystal lattice leaving no space available for guest inclusion. IR spectra reveal nitrogen coordination from stpy and terminal -NCS coordination of the thiocyanate group. The optical reflectance bands 475, 540 (shoulder) and 1022 nm suggest octahedral geometry in accordance with the X-ray data. However, the optical spectrum of acetonitrile solution shows an intense band at 615 nm and a weak shoulder at 570 nm suggesting participation of the solvent molecules in the coordination sphere. These bands indicate the presence of both tetrahedral and octahedral species in solution.

Karunakaran, C.; Thomas, K. R. J.; Shunmugasundaram, A.; Murugesan, R.

2000-05-01

354

Computational spectroscopy, dynamics, and photochemistry of photosensory flavoproteins.  

PubMed

Extensive interest in photosensory proteins stimulated computational studies of flavins and flavoproteins in the past decade. This review is dedicated to the three central topics of these studies: calculations of flavin UV-visible and IR spectra, simulated dynamics of photoreceptor proteins, and flavin photochemistry. Accordingly, this chapter is divided into three parts; each part describes corresponding computational protocols, summarizes computational results, and discusses the emerging mechanistic picture. PMID:24764094

Domratcheva, Tatiana; Udvarhelyi, Anikó; Shahi, Abdul Rehaman Moughal

2014-01-01

355

Recapturing Quantitative Biology.  

ERIC Educational Resources Information Center

Presents a classroom activity on estimating animal populations. Uses shoe boxes and candies to emphasize the importance of mathematics in biology while introducing the methods of quantitative ecology. (JRH)

Pernezny, Ken; And Others

1996-01-01

356

Quantitative Imaging Network  

Cancer.gov

The QIN Imaging Network is designed to promote research and development of quantitative imaging methods for the measurement of tumor response to therapies in clinical trial settings, with the overall goal of facilitating clinical decision-making. The

357

Quantitative Precipitation Forecasting Overview  

NSDL National Science Digital Library

In this module, Wes Junker, retired Senior Branch Forecaster at NCEP/HPC provides an introduction to Quantitative Precipitation Forecasting. This presentation assumes a familiarity with basic meteorological processes.

Comet

2007-11-01

358

Quantitative film radiography  

SciTech Connect

We have developed a system of quantitative radiography in order to produce quantitative images displaying homogeneity of parts. The materials that we characterize are synthetic composites and may contain important subtle density variations not discernible by examining a raw film x-radiograph. In order to quantitatively interpret film radiographs, it is necessary to digitize, interpret, and display the images. Our integrated system of quantitative radiography displays accurate, high-resolution pseudo-color images in units of density. We characterize approximately 10,000 parts per year in hundreds of different configurations and compositions with this system. This report discusses: the method; film processor monitoring and control; verifying film and processor performance; and correction of scatter effects.

Devine, G.; Dobie, D.; Fugina, J.; Hernandez, J.; Logan, C.; Mohr, P.; Moss, R.; Schumacher, B.; Updike, E.; Weirup, D.

1991-02-26

359

Quantitative PCR Protocol  

NSDL National Science Digital Library

This protocol describes how to genotype mice using Quantitative Polymerase Chain Reaction (PCR). The protocol focuses specifically on Ts65Dn mice, but can be used as a basis for genotyping ohter strains.

The Jackson Laboratory (The Jackson Laboratory)

2012-01-06

360

Multivariate Quantitative Chemical Analysis  

NASA Technical Reports Server (NTRS)

Technique of multivariate quantitative chemical analysis devised for use in determining relative proportions of two components mixed and sprayed together onto object to form thermally insulating foam. Potentially adaptable to other materials, especially in process-monitoring applications in which necessary to know and control critical properties of products via quantitative chemical analyses of products. In addition to chemical composition, also used to determine such physical properties as densities and strengths.

Kinchen, David G.; Capezza, Mary

1995-01-01

361

Baryon spectroscopy  

NASA Astrophysics Data System (ADS)

About 120 baryons and baryon resonances are known, from the abundant nucleon with u and d light-quark constituents up to the ?b-=(bsd) , which contains one quark of each generation and to the recently discovered ?b-=(bss) . In spite of this impressively large number of states, the underlying mechanisms leading to the excitation spectrum are not yet understood. Heavy-quark baryons suffer from a lack of known spin parities. In the light-quark sector, quark-model calculations have met with considerable success in explaining the low-mass excitations spectrum but some important aspects such as the mass degeneracy of positive-parity and negative-parity baryon excitations remain unclear. At high masses, above 1.8GeV , quark models predict a very high density of resonances per mass interval which is not yet observed. In this review, issues are identified discriminating between different views of the resonance spectrum; prospects are discussed on how open questions in baryon spectroscopy may find answers from photoproduction and electroproduction experiments which are presently carried out in various laboratories.

Klempt, Eberhard; Richard, Jean-Marc

2010-04-01

362

Molecular Spectroscopy and Remote-Sensing of the Earth's Atmosphere: Progress from Laboratory Studies  

SciTech Connect

In this paper we present some recent developments in the field of molecular spectroscopy applied to the measurement of trace gases in the Earth's atmosphere, in particular concerning the spectroscopy of unstable species or radicals and of isotopic species, but also in the field of quantitative spectroscopy, in the context of more and more challenging requirements arising from modern remote-sensing experiments.

Orphal, Johannes [Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA) University of Paris-12 (Paris-Est), CNRS UMR 7583, 94010 Creteil Cedex (France)

2009-03-11

363

Polar twilight UV-visible radiation field: Perturbations due to multiple scattering, ozone depletion, stratospheric clouds, and surface albedo  

Microsoft Academic Search

The polar twilight atmosphere is different from that at mid-latitude in several ways which lead to significant changes in the wavelength-dependent radiation field. Ozone depletion in the stratosphere leads to increased scattering below 340 nm. Polar stratospheric clouds produce changes in the radiation field which depend on cloud height and thickness. A surface albedo near unity produces a large increase

Anderson D. E. Jr; Steven A. Lloyd

1990-01-01

364

Polar twilight UV-visible radiation field: Perturbations due to multiple scattering, ozone depletion, stratospheric clouds, and surface albedo  

SciTech Connect

The polar twilight atmosphere is different from that at mid-latitude in several ways which lead to significant changes in the wavelength-dependent radiation field. Ozone depletion in the stratosphere leads to increased scattering below 340 nm. Polar stratospheric clouds produce changes in the radiation field which depend on cloud height and thickness. A surface albedo near unity produces a large increase in scattering. Multiple scattering becomes a larger percentage of the radiation field as solar zenith angle increases. These perturbations on the radiation field lead to enhanced ozone destruction in the stratosphere, increased surface irradiance, and a significant wavelength-dependent increase in nadir radiance.

Anderson, D.E., Jr. (Naval Research Lab., Washington, DC (United States)); Lloyd, S.A. (Harvard Univ., Cambridge, MA (United States))

1990-05-20

365

Development and Validation of UV-Visible Spectrophotometric Method for Simultaneous Determination of Eperisone and Paracetamol in Solid Dosage Form  

PubMed Central

Purpose: Eperisone Hydrochloride (EPE) is a potent new generation antispasmodic drug which is used in the treatment of moderate to severe pain in combination with Paracetamol (PAR). Both drugs are available in tablet dosage form in combination with a dose of 50 mg for EPE and 325 mg PAR respectively. Methods: The method is based upon Q-absorption ratio method for the simultaneous determination of the EPE and PAR. Absorption ratio method is used for the ratio of the absorption at two selected wavelength one of which is the iso-absorptive point and other being the ?max of one of the two components. EPE and PAR shows their iso-absorptive point at 260 nm in methanol, the second wavelength used is 249 nm which is the ?max of PAR in methanol. Results: The linearity was obtained in the concentration range of 5-25 ?g/mL for EPE and 2-10 ?g/mL for PAR. The proposed method was effectively applied to tablet dosage form for estimation of both drugs. The accuracy and reproducibility results are close to 100% with 2% RSD. Results of the analysis were validated statistically and found to be satisfactory. The results of proposed method have been validated as per ICH guidelines. Conclusion: A simple, precise and economical spectrophotometric method has been developed for the estimation of EPE and PAR in pharmaceutical formulation. PMID:24312876

Khanage, Shantaram Gajanan; Mohite, Popat Baban; Jadhav, Sandeep

2013-01-01

366

Development of cooled UV, visible and IR windows for quasicontinuous operation of the W7-X stellarator  

SciTech Connect

The stellarator W7-X will be capable of running 30 min discharges. The expected continuous radiation power loads on plasma-facing optical components of 50 kW/m{sup 2} will be predominantly deposited in the form of short wavelength radiation (<60 nm) within the first millimeter of any window material. At such high heat loads actively water cooled windows are essential. The finite element-code ANSYS was used to calculate temperature and stress distributions across the windows for different window materials (CaF{sub 2}, MgF{sub 2}, quartz, ZnSe, sapphire), diameters, and thicknesses to explore any window design limitations resulting from the material properties of the different window substrates. First tests of a prototype water cooled window (coated with water-based colloidal graphite for effective IR absorption) in a specially designed vacuum test chamber equipped with a large surface vacuum compatible high power IR heater are being reported on. The temporal evolution of the temperature at different locations on the air side of the window and its surrounding structure is being monitored by several PT100 resistive thermometers while the spatial heat distribution across the cooled windows on their air and vacuum side is being measured with two IR cameras operating at 4 and 10 {mu}m.

Koenig, R.; Ogorodnikova, O.; Hildebrandt, D.; Grosser, K.; Sehren, C. von; Baldzuhn, J.; Burhenn, R.; Mertens, Ph.; Pospieszczyk, A.; Schweer, B.; Schmidt, H.; Klinger, T. [Max-Planck-Institut fuer Plasmaphysik, Greifswald, EURATOM ASS., D-17491 Greifswald (Germany); Institut fuer Plasmaphysik, FZ-Juelich GmbH, EURATOM ASS., D-52425 Juelich (Germany); Max-Planck-Institut fuer Plasmaphysik, Greifswald, EURATOM ASS., D-17491 Greifswald (Germany)

2004-10-01

367

Penetration of UV-visible solar radiation in the global oceans: Insights from ocean color remote sensing  

NASA Astrophysics Data System (ADS)

Penetration of solar radiation in the ocean is determined by the attenuation coefficient (Kd(?)). Following radiative transfer theory, Kd is a function of angular distribution of incident light and water's absorption and backscattering coefficients. Because these optical products are now generated routinely from satellite measurements, it is logical to evolve the empirical Kd to a semianalytical Kd that is not only spectrally flexible, but also the sun-angle effect is accounted for explicitly. Here, the semianalytical model developed in Lee et al. (2005b) is revised to account for the shift of phase function between molecular and particulate scattering from the short to long wavelengths. Further, using field data collected independently from oligotrophic ocean to coastal waters covering >99% of the Kd range for the global oceans, the semianalytically derived Kd was evaluated and found to agree with measured data within ˜7-26%. The updated processing system was applied to MODIS measurements to reveal the penetration of UVA-visible radiation in the global oceans, where an empirical procedure to correct Raman effect was also included. The results indicated that the penetration of the blue-green radiation for most oceanic waters is ˜30-40% deeper than the commonly used euphotic zone depth; and confirmed that at a depth of 50-70 m there is still ˜10% of the surface UVA radiation (at 360 nm) in most oligotrophic waters. The results suggest a necessity to modify or expand the light attenuation product from satellite ocean-color measurements in order to be more applicable for studies of ocean physics and biogeochemistry.

Lee, Zhongping; Hu, Chuanmin; Shang, Shaoling; Du, Keping; Lewis, Marlon; Arnone, Robert; Brewin, Robert

2013-09-01

368

Penetration of UV-visible solar radiation in the global oceans: Insights from ocean color remote sensing  

E-print Network

()). Following radiative transfer theory, Kd is a function of angular distribution of incident light and water molecular and particulate scattering from the short to long wavelengths. Further, using field data collected

369

The effects of preen oils and soiling on the UV–visible reflectance of carotenoid-pigmented feathers  

Microsoft Academic Search

Plumage coloration, particularly when carotenoid-based, is important in social signaling in birds. Although feather color\\u000a is a relatively stable trait, individuals may modify it with “cosmetic” substances such as preen oils. In addition, dirt accumulation\\u000a may influence plumage coloration and further affect signal perception by receivers. Here, we analyze the separate potential\\u000a effects of preen oils and soil accumulation on

Lorenzo Pérez-Rodríguez; Francois Mougeot; Gary R. Bortolotti

2011-01-01

370

Effective mitigation of photodarkening in Yb-doped lasers based on Al-silicate using UV/visible light  

NASA Astrophysics Data System (ADS)

In this work we discuss the impact of visible light radiation on photodarkening generation in 1070-nm Yb-doped fiber lasers. Simultaneous photodarkening and photobleaching effects induced by 976 nm and 405 nm or 550 nm radiations respectively were investigated. We observed a significant photobleaching effect due to 405 nm radiation but not a complete recovery. A strong absorption of the 405 nm radiation by the excited ions (Excited-State Absorption) was also observed and found as a main limiting factor for the bleaching performance together with observation of photodarkening losses induced by ground-state absorption. To proper define the optimum bleaching wavelength we report, for the first time to the best of our knowledge, the Excited-State Absorption cross section in the visible range. The reported experiments allow to individuate the main parameters defining the optimum bleaching wavelength. In a final experiment, using optimized 550-nm wavelength bleaching radiation, we were able to operate a laser at 93% of its pristine power level compensating a power drop of about 45% in absence of bleaching. The method we present is an effective yet simple way to run laser using standard Al-silicate fibers with doping level over 1026 ions/m3 and high inversion.

Piccoli, Riccardo; Robin, Thierry; Méchin, David; Brand, Thomas; Klotzbach, Udo; Taccheo, Stefano

2014-03-01

371

Quantitative Glycomics Strategies*  

PubMed Central

The correlations between protein glycosylation and many biological processes and diseases are increasing the demand for quantitative glycomics strategies enabling sensitive monitoring of changes in the abundance and structure of glycans. This is currently attained through multiple strategies employing several analytical techniques such as capillary electrophoresis, liquid chromatography, and mass spectrometry. The detection and quantification of glycans often involve labeling with ionic and/or hydrophobic reagents. This step is needed in order to enhance detection in spectroscopic and mass spectrometric measurements. Recently, labeling with stable isotopic reagents has also been presented as a very viable strategy enabling relative quantitation. The different strategies available for reliable and sensitive quantitative glycomics are herein described and discussed. PMID:23325767

Mechref, Yehia; Hu, Yunli; Desantos-Garcia, Janie L.; Hussein, Ahmed; Tang, Haixu

2013-01-01

372

Quantitative Hydrocarbon Surface Analysis  

NASA Technical Reports Server (NTRS)

The elimination of ozone depleting substances, such as carbon tetrachloride, has resulted in the use of new analytical techniques for cleanliness verification and contamination sampling. The last remaining application at Rocketdyne which required a replacement technique was the quantitative analysis of hydrocarbons by infrared spectrometry. This application, which previously utilized carbon tetrachloride, was successfully modified using the SOC-400, a compact portable FTIR manufactured by Surface Optics Corporation. This instrument can quantitatively measure and identify hydrocarbons from solvent flush of hardware as well as directly analyze the surface of metallic components without the use of ozone depleting chemicals. Several sampling accessories are utilized to perform analysis for various applications.

Douglas, Vonnie M.

2000-01-01

373

Qualitative and quantitative analysis of mixtures of compounds containing both hydrogen and deuterium  

NASA Technical Reports Server (NTRS)

Method allows qualitative and quantitative analysis of mixtures of partially deuterated compounds. Nuclear magnetic resonance spectroscopy determines location and amount of deuterium in organic compounds but not fully deuterated compounds. Mass spectroscopy can detect fully deuterated species but not the location.

Crespi, H. L.; Harkness, L.; Katz, J. J.; Norman, G.; Saur, W.

1969-01-01

374

Critical Quantitative Inquiry in Context  

ERIC Educational Resources Information Center

This chapter briefly traces the development of the concept of critical quantitative inquiry, provides an expanded conceptualization of the tasks of critical quantitative research, offers theoretical explanation and justification for critical research using quantitative methods, and previews the work of quantitative criticalists presented in this…

Stage, Frances K.; Wells, Ryan S.

2014-01-01

375

Quantitative Graphics in Newspapers.  

ERIC Educational Resources Information Center

The use of quantitative graphics in newspapers requires achieving a balance between being accurate and getting the attention of the reader. The statistical representations in newspapers are drawn by graphic designers whose key technique is fusion--the striking combination of two visual images. This technique often results in visual puns,…

Tankard, James W., Jr.

376

Quantitative criteria for insomnia  

Microsoft Academic Search

Formal diagnostic systems (DSM-IV, ICSD, and ICD-10) do not provide adequate quantitative criteria to diagnose insomnia. This may not present a serious problem in clinical settings where extensive interviews determine the need for clinical management. However, lack of standard criteria introduce disruptive variability into the insomnia research domain. The present study reviewed two decades of psychology clinical trials for insomnia

K. L. Lichstein; H. H. Durrence; D. J. Taylor; A. J. Bush; B. W. Riedel

2003-01-01

377

Identification of residues by infrared spectroscopy  

SciTech Connect

Mid-infrared spectroscopy of surfaces can be a very powerful technique for the qualitative and quantitative analysis of surface residues. The goal of this work was to study the application of diffuse reflectance mid-infrared spectroscopy to the identification of pesticide, herbicide, and explosive residues on surfaces. A field portable diffuse reflectance spectrometer was used to collect the mid-infrared spectra of clean surfaces and contaminated surfaces. These spectra were used as calibration sets to develop automated data analysis to classify or to identify residues on samples. In this presentation, the instrumentation and data process algorithms will be discussed.

Barber, T.E.; Ayala, N.L.; Jin, Hong; Drumheller, C.T. [Sam Houston State Univ., Huntsville, TX (United States)] [and others

1997-12-31

378

pubs.acs.org/cmPublished on Web 08/09/2010r 2010 American Chemical Society Chem. Mater. 2010, 22, 49394949 4939  

E-print Network

microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, UV-visible spectroscopy, and electrical Although vapor- phase methods can produce high quality ITO films, they have practical disadvantages of high

379

The role of Fe and Co dopants during the activation of the VO(HPO{sub 4}) {sm_bullet} 0.5H{sub 2}O precursor of the vanadium phosphorus catalyst as studied by in situ laser Raman spectroscopy  

SciTech Connect

The activation of two Fe- and Co-doped VO(HPO{sub 4}){center_dot} 0.5 H{sub 2}O precursors under n-butane/air catalytic atmosphere (1.5%) has been compared to the corresponding undoped precursor prepared under the same conditions by the organic route of reduction of V{sub 2}O{sub 5} by isobutanol. The modification of the structure of the VPO materials has been followed by in situ laser Raman spectroscopy during the activation on line. It is evidenced that doping promotes the oxidation of the catalysts favoring the VOPO{sub 4}/(VO){sub 2}P{sub 2}O{sub 7} balance. This is confirmed by an analysis of the bulk and surface composition of the final catalysts by UV-visible, XPS spectroscopy and {sup 31}P NMR by spin-echo mapping. The role of the two dopants is shown to be different on the catalytic performances: both Co and Fe dopants improve strongly selectivity to maleic anhydride but n-butane conversion is decreased for Co and increased for Fe. This has been explained by a different dispersion of VOPO{sub 4} phases on the (VO){sub 2}P{sub 2}O{sub 7} matrix during the activation process as compared to the same undoped VPO catalyst. 31 refs., 15 figs., 2 tabs.

Abdelouahab, F.B.; Volta, J.C.; Olier, R. [Institut de Recherches sur la Catalyse, Villeurbanne (France)] [and others] [Institut de Recherches sur la Catalyse, Villeurbanne (France); and others

1995-12-01

380

Energy & Climate: Getting Quantitative  

NASA Astrophysics Data System (ADS)

A noted environmentalist claims that buying an SUV instead of a regular car is energetically equivalent to leaving your refrigerator door open for seven years. A fossil-fuel apologist argues that solar energy is a pie-in-the-sky dream promulgated by na"ive environmentalists, because there's nowhere near enough solar energy to meet humankind's energy demand. A group advocating shutdown of the Vermont Yankee nuclear plant claims that 70% of its electrical energy is lost in transmission lines. Around the world, thousands agitate for climate action, under the numerical banner ``350.'' Neither the environmentalist, the fossil-fuel apologist, the antinuclear activists, nor most of those marching under the ``350'' banner can back up their assertions with quantitative arguments. Yet questions about energy and its environmental impacts almost always require quantitative answers. Physics can help! This poster gives some cogent examples, based on the newly published 2^nd edition of the author's textbook Energy, Environment, and Climate.

Wolfson, Richard

2011-11-01

381

Primary enzyme quantitation  

DOEpatents

The disclosure relates to the quantitation of a primary enzyme concentration by utilizing a substrate for the primary enzyme labeled with a second enzyme which is an indicator enzyme. Enzyme catalysis of the substrate occurs and results in release of the indicator enzyme in an amount directly proportional to the amount of primary enzyme present. By quantifying the free indicator enzyme one determines the amount of primary enzyme present.

Saunders, G.C.

1982-03-04

382

Quantitative quantum chemistry  

Microsoft Academic Search

We review the current status of quantum chemistry as a predictive tool of chemistry and molecular physics, capable of providing highly accurate, quantitative data about molecular systems. We begin by reviewing wave-function based electronic-structure theory, emphasizing the N-electron hierarchy of coupled-cluster theory and the one-electron hierarchy of correlation-consistent basis sets. Following a discussion of the slow basis-set convergence of dynamical

Trygve Helgaker; Wim Klopper; David P. Tew

2008-01-01

383

Modern quantitative schlieren techniques  

NASA Astrophysics Data System (ADS)

Schlieren optical techniques have traditionally been used to qualitatively visualize refractive flowfields in transparent media. Modern schlieren optics, however, are increasingly focused on obtaining quantitative information such as temperature and density fields in a flow -- once the sole purview of interferometry -- without the need for coherent illumination. Quantitative data are obtained from schlieren images by integrating the measured refractive index gradient to obtain the refractive index field in an image. Ultimately this is converted to a density or temperature field using the Gladstone-Dale relationship, an equation of state, and geometry assumptions for the flowfield of interest. Several quantitative schlieren methods are reviewed here, including background-oriented schlieren (BOS), schlieren using a weak lens as a "standard," and "rainbow schlieren." Results are presented for the application of these techniques to measure density and temperature fields across a supersonic turbulent boundary layer and a low-speed free-convection boundary layer in air. Modern equipment, including digital cameras, LED light sources, and computer software that make this possible are also discussed.

Hargather, Michael; Settles, Gary

2010-11-01

384

Project LITE Spectroscopy  

NASA Astrophysics Data System (ADS)

Spectroscopy is one of the most important tools used by astronomers to disentangle information about the universe. However, it is one of the most challenging subjects in undergraduate astronomy courses. Among the most difficult concepts for students to master are Kirchhoff's laws, blackbody radiation, the Stefan-Boltzmann law, Wien's law, the nature and causes of emission and absorption lines, and the relation of spectra to the underlying astronomical and physical processes producing them. Students often seem baffled by the connection between a spectrum seen visually as a color band and the same spectrum plotted graphically as intensity versus wavelength or frequency. Project LITE (Light Inquiry Through Experiments) is a software, curriculum, and materials development project at Boston University. As part of the project, we are currently developing a suite of spectroscopic tools for astronomy education. We are also assessing their effectiveness in improving conceptual understanding of spectroscopic phenomena by astronomy students at the undergraduate level. The spectroscopy component of Project LITE includes take-home laboratory materials and experiments, which are integrated with web-based software. We have also developed a novel quantitative handheld binocular spectrometer (patent pending). Here we present an overview of the Project LITE homelab kits and curriculum, the Spectrum Explorer, and the Project LITE spectrometer. The homelab experiments and the Spectrum Explorer have been tested with students in a non-science majors introductory astronomy course as well as in a School of Education course for prospective elementary school science teachers. We present preliminary results of pre- and post-instruction surveys of student understanding of various spectral properties of light both from students who used the homelab activities and the Spectrum Explorer and those who did not. The Spectrum Explorer (along with many other applets about both the physical and perceptual nature of light) can be found at the Project LITE web site http://lite.bu.edu. Project LITE is supported by Grant #DUE-0125992 from the National Science Foundation Division of Undergraduate Education. E. W. is supported by a NASA Graduate Student Research Fellowship, NASA Grant number NGT5-50482.

Weeks, E.; Brecher, K.; Carr, P.; Garik, P.

2003-12-01

385

Electron-impact spectroscopy  

NASA Technical Reports Server (NTRS)

The methods of electron impact spectroscopy and cross section measurements are discussed and compared to optical spectroscopy. A brief summary of the status of this field and the available data is given.

Trajmar, S.

1990-01-01

386

Quantitatively probing the Al distribution in zeolites.  

PubMed

The degree of substitution of Si(4+) by Al(3+) in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. Because the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and (27)Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations, allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in an HBEA150 zeolite has been determined using this analysis. PMID:24815517

Vjunov, Aleksei; Fulton, John L; Huthwelker, Thomas; Pin, Sonia; Mei, Donghai; Schenter, Gregory K; Govind, Niranjan; Camaioni, Donald M; Hu, Jian Zhi; Lercher, Johannes A

2014-06-11

387

Quantitative biomedical mass spectrometry  

NASA Astrophysics Data System (ADS)

The scope of this contribution is an illustration of the capabilities of isotope dilution mass spectrometry (IDMS) for quantification of target substances in the biomedical field. After a brief discussion of the general principles of quantitative MS in biological samples, special attention will be paid to new technological developments or trends in IDMS from selected examples from the literature. The final section will deal with the use of IDMS for accuracy assessment in clinical chemistry. Methodological aspects considered crucial for avoiding sources of error will be discussed.

de Leenheer, Andrép; Thienpont, Linda M.

1992-09-01

388

Quantitative molecular methods in virology  

Microsoft Academic Search

Summary During the past few years, significant technical effort was made to develop molecular methods for the absolute quantitation of nucleic acids in biological samples. In virology, semi-quantitative and quantitative techniques of different principle, complexity, and reliability were designed, optimized, and applied in basic and clinical researches. The principal data obtained in successful pilot applications in vivo are reported in

M. Clementi; S. Menzo; A. Manzin; P. Bagnarelli

1995-01-01

389

Quantitative Hyperspectral Reflectance Imaging  

PubMed Central

Hyperspectral imaging is a non-destructive optical analysis technique that can for instance be used to obtain information from cultural heritage objects unavailable with conventional colour or multi-spectral photography. This technique can be used to distinguish and recognize materials, to enhance the visibility of faint or obscured features, to detect signs of degradation and study the effect of environmental conditions on the object. We describe the basic concept, working principles, construction and performance of a laboratory instrument specifically developed for the analysis of historical documents. The instrument measures calibrated spectral reflectance images at 70 wavelengths ranging from 365 to 1100 nm (near-ultraviolet, visible and near-infrared). By using a wavelength tunable narrow-bandwidth light-source, the light energy used to illuminate the measured object is minimal, so that any light-induced degradation can be excluded. Basic analysis of the hyperspectral data includes a qualitative comparison of the spectral images and the extraction of quantitative data such as mean spectral reflectance curves and statistical information from user-defined regions-of-interest. More sophisticated mathematical feature extraction and classification techniques can be used to map areas on the document, where different types of ink had been applied or where one ink shows various degrees of degradation. The developed quantitative hyperspectral imager is currently in use by the Nationaal Archief (National Archives of The Netherlands) to study degradation effects of artificial samples and original documents, exposed in their permanent exhibition area or stored in their deposit rooms.

Klein, Marvin E.; Aalderink, Bernard J.; Padoan, Roberto; de Bruin, Gerrit; Steemers, Ted A.G.

2008-01-01

390

Doping of carbon nanotubes with nitrogen improves protein coverage whilst retaining correct conformation  

NASA Astrophysics Data System (ADS)

Relevant parameters for non-covalent protein functionalization of carbon nanotubes are explored. Multiwalled carbon nanotubes are carboxylated and functionalized with metalloproteins. Using atomic force microscopy (AFM) we quantitatively determine that coverage with nitrogen-doped multiwalled carbon nanotubes is superior compared to coverage with un-doped multiwalled carbon nanotubes, due to enhanced carboxylation. Conformational analysis using a combination of AFM, antibody binding assays, circular dichroism and UV-visible spectroscopy demonstrates that the metalloproteins retain their native structure when adsorbed to nitrogen-doped multiwalled carbon nanotubes irrespective of their size, charge or folding motif.

Burch, Hilary J.; Antoranz Contera, Sonia; de Planque, Maurits R. R.; Grobert, Nicole; Ryan, J. F.

2008-09-01

391

Field spectroscopy of agricultural crops  

NASA Technical Reports Server (NTRS)

The development of the full potential of multispectral data acquired from satellites, requires quantitative knowledge, and physical models of the spectral properties of specific earth surface features. Knowledge of the relationships between spectral-radiometric characteristics and important biophysical parameters of agricultural crops and soils can best be obtained by carefully controlled studies of fields or plots. It is important to select plots where data describing the agronomic-biophysical properties of the crop canopies and soil background are attainable, taking into account also the feasibility of frequent timely calibrated spectral measurements. The term 'field spectroscopy' is employed for this research. The present paper is concerned with field research which was sponsored by NASA as part of the AgRISTARS Supporting Research Project. Attention is given to field research objectives, field research instrumentation, measurement procedures, spectral-temporal profile modeling, and the effects of cultural and environmental factors on crop reflectance.

Bauer, M. E.; Daughtry, C. S. T.; Biehl, L. L.; Kanemasu, E. T.; Hall, F. G.

1986-01-01

392

Supercritical Angle Fluorescence Correlation Spectroscopy  

PubMed Central

We explore the potential of a supercritical angle (SA) objective for fluorescence correlation spectroscopy (FCS). This novel microscope objective combines tight focusing by an aspheric lens with strong axial confinement of supercritical angle fluorescence collection by a parabolic mirror lens, resulting in a small detection volume. The tiny axial extent of the detection volume features an excellent surface sensitivity, as is demonstrated by diffusion measurements in model membranes with an excess of free dye in solution. All SA-FCS measurements are directly compared to standard confocal FCS, demonstrating a clear advantage of SA-FCS, especially for diffusion measurements in membranes. We present an extensive theoretical framework that allows for accurate and quantitative evaluation of the SA-FCS correlation curves. PMID:17827221

Ries, Jonas; Ruckstuhl, Thomas; Verdes, Dorinel; Schwille, Petra

2008-01-01

393

Effect of photobleaching on calibration model development in biological Raman spectroscopy  

E-print Network

A major challenge in performing quantitative biological studies using Raman spectroscopy lies in overcoming the influence of the dominant sample fluorescence background. Moreover, the prediction accuracy of a calibration ...

Barman, Ishan

394

Quantitative analysis of complexes in electron irradiated CZ silicon  

Microsoft Academic Search

Complexes in helium or electron irradiated silicon are quantitatively analyzed by highly sensitive and accurate infrared (IR) absorption spectroscopy. Carbon concentration (1×1015–1×1017cm?3) and helium dose (5×1012–5×1013cm?2) or electron dose (1×1015–1×1017cm?2) are changed by two orders of magnitude in relatively low regime compared to the previous works. It is demonstrated that the carbon-related complex in low carbon concentration silicon of commercial

N. Inoue; H. Ohyama; Y. Goto; T. Sugiyama

2007-01-01

395

Application of the quantitative IR analysis of copolymers of trioxane  

Microsoft Academic Search

The copolymers of trioxane and 5 to 50% phenyl- or n-butyl glycidyl ethers were Investigated with elemental anlysis and IR spectroscopy. Using as an internal standard the methylene absorbance at 1470 sm?1 and the absorbance of C?O?C groups at 900, 930, 1100 and 1240 sm?1), it was determined that the absorbance at 1100 sm?1 is available for quantitative IR analysis

G. Sirashki; Iv. Glavchev; R. Mateva

1997-01-01

396

Quantitative dynamic footprinting microscopy.  

PubMed

Quantitative dynamic footprinting (qDF) allows visualization of the footprints of live leukocytes rolling on a selectin-coated cover glass. qDF works on the principle of total internal reflection fluorescence, which involves fluorescence excitation in a thin slice (~200 nm) of the cell proximal to the cover glass while the rest of the cell remains dark. Dual color qDF (DqDF) is an advancement of qDF, which enables simultaneous visualization of two fluorochromes in the footprints of rolling leukocytes. When the fluorochrome is localized either in the cell cytoplasm or plasma membrane, the two-dimensional qDF image is used to create a three-dimensional rendition of the footprint topography. DqDF is a useful tool to study leukocyte adhesion under flow, and has recently been used to reveal mechanisms that enable neutrophils to roll at high shear stresses that prevail in venules during inflammation. PMID:23478358

Sundd, Prithu; Ley, Klaus

2013-04-01

397

Quantitative Impact Study (QIS)  

NSDL National Science Digital Library

The Bank of International Settlements is offering information on its Quantitative Impact Study, which will assess "whether the Committee has met its goals with regard to the New Basel Capital Accord" of 1999. The site contains all 37 pages of the questionnaire being sent to international banks along with short explanations of the study's methods and modes. The questionnaire is in Excel format and includes three main chapters covering general information about each bank, details of the standardized approaches to credit risk assessment, and the International Ratings-Based Approach (IRB) taken by each bank. The site also links to a Website on the New Basel Capital Accord, a more risk-sensitive framework than the original Basel Capital Accord which was written in the year previous.

398

Quantitative stratigraphic inversion  

NASA Astrophysics Data System (ADS)

We develop a methodology for systematic inversion of quantitative stratigraphic models. Quantitative stratigraphic modeling predicts stratigraphy using numerical simulations of geologic processes. Stratigraphic inversion methodically searches the parameter space in order to detect models which best represent the observed stratigraphy. Model parameters include sea-level change, tectonic subsidence, sediment input rate, and transport coefficients. We successfully performed a fully automated process based stratigraphic inversion of a geologically complex synthetic model. Several one and two parameter inversions were used to investigate the coupling of process parameters. Source location and transport coefficient below base level indicated significant coupling, while the rest of the parameters showed only minimal coupling. The influence of different observable data on the inversion was also tested. The inversion results using misfit based on sparse, but time dependent sample points proved to be better than the misfit based on the final stratigraphy only, even when sampled densely. We tested several inversion schemes on the topography dataset obtained from the eXperimental EarthScape facility simulation. The clustering of model parameters in most of the inversion experiments showed the likelihood of obtaining a reasonable number of compatible models. We also observed the need for several different dillusion-coefficient parameterizations to emulate different erosional and depositional processes. The excellent result of the piecewise inversion, which used different parameterizations for different time intervals, demonstrate the need for development or incorporation of time-variant parameterizations of the diffusion coefficients. We also present new methods for applying boundary condition on simulation of diffusion processes using the finite-difference method. It is based on the straightforward idea that solutions at the boundaries are smooth. The new scheme achieves high accuracy when the initial conditions are non vanishing at the boundaries, a case which is poorly handled by previous methods. Along with the ease in implementation, the new method does not require any additional computation or memory.

Sharma, Arvind Kumar

399

Quantitative evolutionary design  

PubMed Central

The field of quantitative evolutionary design uses evolutionary reasoning (in terms of natural selection and ultimate causation) to understand the magnitudes of biological reserve capacities, i.e. excesses of capacities over natural loads. Ratios of capacities to loads, defined as safety factors, fall in the range 1.2-10 for most engineered and biological components, even though engineered safety factors are specified intentionally by humans while biological safety factors arise through natural selection. Familiar examples of engineered safety factors include those of buildings, bridges and elevators (lifts), while biological examples include factors of bones and other structural elements, of enzymes and transporters, and of organ metabolic performances. Safety factors serve to minimize the overlap zone (resulting in performance failure) between the low tail of capacity distributions and the high tail of load distributions. Safety factors increase with coefficients of variation of load and capacity, with capacity deterioration with time, and with cost of failure, and decrease with costs of initial construction, maintenance, operation, and opportunity. Adaptive regulation of many biological systems involves capacity increases with increasing load; several quantitative examples suggest sublinear increases, such that safety factors decrease towards 1.0. Unsolved questions include safety factors of series systems, parallel or branched pathways, elements with multiple functions, enzyme reaction chains, and equilibrium enzymes. The modest sizes of safety factors imply the existence of costs that penalize excess capacities. Those costs are likely to involve wasted energy or space for large or expensive components, but opportunity costs of wasted space at the molecular level for minor components. PMID:12122135

Diamond, Jared

2002-01-01

400

Quantitative analysis of NMR spectra with chemometrics  

NASA Astrophysics Data System (ADS)

The number of applications of chemometrics to series of NMR spectra is rapidly increasing due to an emerging interest for quantitative NMR spectroscopy e.g. in the pharmaceutical and food industries. This paper gives an analysis of advantages and limitations of applying the two most common chemometric procedures, Principal Component Analysis (PCA) and Multivariate Curve Resolution (MCR), to a designed set of 231 simple alcohol mixture (propanol, butanol and pentanol) 1H 400 MHz spectra. The study clearly demonstrates that the major advantage of chemometrics is the visualisation of larger data structures which adds a new exploratory dimension to NMR research. While robustness and powerful data visualisation and exploration are the main qualities of the PCA method, the study demonstrates that the bilinear MCR method is an even more powerful method for resolving pure component NMR spectra from mixtures when certain conditions are met.

Winning, H.; Larsen, F. H.; Bro, R.; Engelsen, S. B.

2008-01-01

401

SPECTROSCOPIE DE DEFAUTS -LUMINESCENCE I. THE ANALYSIS OF WIDE BAND GAP SEMICONDUCTORS  

E-print Network

SPECTROSCOPIE DE DEFAUTS - LUMINESCENCE I. THE ANALYSIS OF WIDE BAND GAP SEMICONDUCTORS BY OPTICAL impuretes, le texte principal met I'accent sur la spectroscopie d'absorption et de luminescence. L a la detec- tion et la reconnaissance (luminescence) ou a 1'Cvaluation quantitative (absorption) de

Boyer, Edmond

402

Electrochemistry and spectroscopy of electrolytes and cathode materials in room-temperature ionic liquids  

NASA Astrophysics Data System (ADS)

The demonstration of a stable, reversible, alkali metal anode is an important step in the development of practical secondary batteries using room temperature chloroaluminate molten salts as electrolytes. Such melts are made by mixing 1-ethyl-3-methylimidazolium chloride (EMIC) with aluminum chloride, and can be Lewis buffered by adding LiCl or NaCl. It has been shown previously that protons added to a sodium chloride buffered melt as 1-ethyl-3-methyfimidazolium hydrogen dichloride (EMIHCl2) provide a more negative voltage window and nearly reversible deposition-stripping behavior for sodium. It is reported here that triethanolamine hydrogen chloride is effective in widening the voltage window, allows the plating and stripping of both lithium and sodium, and is stable in buffered EMIC/AlCl3 melts for months. It is suggested that deprotonation of one ethanolic group of triethanolamine HCl is responsible for the effect. The electrochemistry and UV-visible spectroscopy of several vanadium oxides have been examined in room temperature melts. By varying the mole ratio of the two components, Lewis basic, neutral and acidic melts were made. Most oxides have very low solubility: V2O4 and V2O3 are insoluble and V2O5 has a solubility limit less than 5 mM, but the solubilities of the salts NaVO 3, Na3VO4, and NH4VO3, VOCl 3 and VOF3 are significantly higher. The electrochemistry of V2O5, NaVO3, Na3VO4, NH4VO3, VOCl3 and VOF3 is similar in neutral and acidic melts. In the neutral melt each compound shows an irreversible reduction at about 0.45V vs. an Al wire reference electrode. In an acidic melt (mole fraction AlCl3 = 0.55) each of these compounds exhibit additional reduction peaks at more positive potentials. Coulometric and spectroscopic data for the 0.45V reduction suggest that mixed oxidation state polyvanadates may be formed. Controlled potential coulometry demonstrated that the reduction at 0.45V was the reduction of V(V) to V(IV) and the more positive reduction peaks were caused by the reduction of some other species of V(V) present in the acidic melts. New room temperature melts have been prepared by mixing Lewis acidic, VOCl3, with Lewis basic, EMIC. The new melts are dark red homogeneous liquids that are very conductive and easily reduced.

Ryan, David Martin

403

Quantitative schlieren visualization.  

PubMed

Using a closed circuit television camera (CCTV), a method is developed to obtain quantitative sound pressure measurements directly from the sound field imaged in a schlieren system. By using the exact time format of the composite video signal and a series of time delay circuits, it is possible to take vertical intensity scans of a schlieren image at any position on the TV raster. The method uses the camera's horizontal blanking pulse to trigger a broadband, high-speed sample-hold amplifier. This amplifier is triggered to sample each horizontal scan line at a selected time in the horizontal scan sweep and to feed this value into a transient recorder. The signal is digitized, and a continuous analog voltage signal corresponding to the black-white information from a schlieren image is displayed on a scope. The same analog signal is also plotted on an X-Y recorder. The schlieren system can be operated using only a single calibration curve at each frequency. The curves plotted applied transducer voltage against the video output level. Thus, by comparing the video output levels for several vertical image intensity scans on a schlieren image, relative sound pressure measurements are routinely obtained. PMID:20197881

Stanic, S

1978-03-01

404

Molecular Sensors for Moisture Detection by Mössbauer Spectroscopy  

Microsoft Academic Search

A parameter of importance in various industrial and commercial applications is sensitivity to moisture. A new class of molecular sensors which enable the qualitative and quantitative determination of air moisture (high selectivity and sensitivity) by application of Mössbauer spectroscopy as the probe technique has been investigated. The electronic properties of the iron-containing sensor depend upon the presence of moisture which

F. Renz; P. A. de Souza; G. Klingelhöfer; H. A. Goodwin

2002-01-01

405

ANALYSIS OF ATMOSPHERIC ORGANIC AEROSOLS BY MASS SPECTROSCOPY  

EPA Science Inventory

High resolution mass spectroscopy has been found to be a useful means of characterizing the organic fraction of urban aerosols. Quantitative accuracy, however, was limited, particularly for compounds of low abundance. Some ambiguities were found in the assignment of origins of io...

406

BATSE spectroscopy analysis system  

NASA Technical Reports Server (NTRS)

The Burst and Transient Source Experiment (BATSE) Spectroscopy Analysis System (BSAS) is the software system which is the primary tool for the analysis of spectral data from BATSE. As such, Guest Investigators and the community as a whole need to know its basic properties and characteristics. Described here are the characteristics of the BATSE spectroscopy detectors and the BSAS.

Schaefer, Bradley E.; Bansal, Sandhia; Basu, Anju; Brisco, Phil; Cline, Thomas L.; Friend, Elliott; Laubenthal, Nancy; Panduranga, E. S.; Parkar, Nuru; Rust, Brad

1992-01-01

407

Quantitative imaging of turbulent and reacting flows  

SciTech Connect

Quantitative digital imaging, using planar laser light scattering techniques is being developed for the analysis of turbulent and reacting flows. Quantitative image data, implying both a direct relation to flowfield variables as well as sufficient signal and spatial dynamic range, can be readily processed to yield two-dimensional distributions of flowfield scalars and in turn two-dimensional images of gradients and turbulence scales. Much of the development of imaging techniques to date has concentrated on understanding the requisite molecular spectroscopy and collision dynamics to be able to determine how flowfield variable information is encoded into the measured signal. From this standpoint the image is seen as a collection of single point measurements. The present effort aims at realizing necessary improvements in signal and spatial dynamic range, signal-to-noise ratio and spatial resolution in the imaging system as well as developing excitation/detection strategies which provide for a quantitative measure of particular flowfield scalars. The standard camera used for the study is an intensified CCD array operated in a conventional video format. The design of the system was based on detailed modeling of signal and image transfer properties of fast UV imaging lenses, image intensifiers and CCD detector arrays. While this system is suitable for direct scalar imaging, derived quantities (e.g. temperature or velocity images) require an exceptionally wide dynamic range imaging detector. To apply these diagnostics to reacting flows also requires a very fast shuttered camera. The authors have developed and successfully tested a new type of gated low-light level detector. This system relies on fast switching of proximity focused image-diode which is direct fiber-optic coupled to a cooled CCD array. Tests on this new detector show significant improvements in detection limit, dynamic range and spatial resolution as compared to microchannel plate intensified arrays.

Paul, P.H. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01

408

Rigor in Traditional Quantitative Methods.  

ERIC Educational Resources Information Center

This paper offers reasons for using traditional quantitative research methods and illustrates some of the considerations demanding rigor in a study on gender discrimination in school-administrator salaries. Traditional quantitative methods provide a meaningful language based on numbers and objectivity, and they are less time-consuming and complex…

Pounder, Diana G.

409

Developing Geoscience Students' Quantitative Skills  

Microsoft Academic Search

Sophisticated quantitative skills are an essential tool for the professional geoscientist. While students learn many of these sophisticated skills in graduate school, it is increasingly important that they have a strong grounding in quantitative geoscience as undergraduates. Faculty have developed many strong approaches to teaching these skills in a wide variety of geoscience courses. A workshop in June 2005 brought

C. A. Manduca; G. S. Hancock

2005-01-01

410

Facile Synthesis of Hollow ZnS Nanospheres in Block Copolymer Solutions  

E-print Network

was maintained under a static condition at 27 °C for 10 h, and the slow release of S2- ions from TAA led-2000, Cu KR radiation), UV-visible spectroscopy (Shimadzu UV-250), and thermogravi- metric analysis

Qi, Limin

411

Effect of heterogeneity on the quantitative determination of trace elements in concrete  

Microsoft Academic Search

Laser-induced breakdown spectroscopy has been used for quantitative measurement of trace elements, e.g. sulfur and chlorine,\\u000a in concrete. Chloride and sulfate ions have a large effect on the durability of concrete structures, and quantitative measurement\\u000a is important for condition assessment and quality assurance. Concrete is a highly heterogeneous material in composition and\\u000a grain-size distribution, i.e. the spatial distribution of elements.

Friederike Weritz; Dieter Schaurich; Alexander Taffe; Gerd Wilsch

2006-01-01

412

Applications of FTNIR spectroscopy to process monitoring  

NASA Astrophysics Data System (ADS)

For years, near infrared spectroscopy has been aggressively promoted and successfully used as a quantitative tool for accurately measuring parameters of remarkably varied materials. Using sophisticated statistical software, the instruments extract correlations between a measured absorbance signal in the spectrum and the property or concentration of interest. From food products to gasoline octane, NIR has been demonstrated to perform well, but nagging reliability and calibration issues persist. Using Fourier Transform techniques in the NIR largely eliminates vexing problems the dispersive units suffer. FT-NIR analyzers offer the same sampling and software capability, but add reliability and stability to the measurement. This paper details several applications of process FT-NIR to complex quantitative analyses in industry and describes recent improvements in fiber optic sampling tools which have further advanced the role of FT-NIR for on-line analyses.

Peters, David C.; Shearer, James C.

1993-12-01

413

Toward pure electronic spectroscopy  

E-print Network

In this thesis is summarized the progress toward completing our understanding of the Rydberg system of CaF and developing Pure Electronic Spectroscopy. The Rydberg system of CaF possesses a paradigmatic character due to ...

Petrovi?, Vladimir, 1978-

2009-01-01

414

Light Meson Spectroscopy  

E-print Network

We survey the current status of light meson spectroscopy. We begin with a general introduction to meson spectroscopy and and its importance in understanding the physical states of Quantum Chromo Dynamics (QCD). Phemenological models of hadron spectroscopy are described with particular emphasis on the constituent quark model and the qualitative features it predicts for the meson spectrum. We next discuss expectations for hadrons lying outside the quark model, such as hadron states with excited gluonic degrees of freedom. These states include so-called hybrids glueballs}, as well as multiquark states. The established meson states are compared to the quark model predictions and we find that most meson states are well described by the quark model. However, a number of states in the light-quark sector do not fit in well, suggesting the existence of hadronic states with additional degrees of freedom. We end with a brief description of future directions in meson spectroscopy.

Stephen Godfrey; Jim Napolitano

1998-11-19

415

Perspectives in hadron spectroscopy  

E-print Network

A brief survey is presented of selected recent results in hadron spectroscopy and related theoretical studies. This includes the pentaquarks and hadrons containing one or two charmed quarks or antiquarks.

J. M. Richard

2005-11-17

416

Nuclear Magnetic Resonance Spectroscopy  

NSDL National Science Digital Library

This website serves as a primer for understanding the fundamentals of NMR spectroscopy. Plenty of useful figures and animations that enhance the understanding of nuclear spin, shielding, and how these phenomena serve as the basis for NMR.

2011-05-18

417

Fourier-transform absorption spectroscopy in reciprocating engines.  

PubMed

We have adapted our in-cylinder Fourier-transform spectroscopy technique to measure absorption spectra in a reciprocating engine. Previously, we had used the technique for emission spectroscopy; the upgrade to absorption spectroscopy mode is important because it allows for more quantitative analysis of gas properties than is possible with emission spectroscopy. Here, we discuss fuel, H(2)O, and CO(2) spectra measured in an engine using a spark-plug-based probe for optical access and use the water portion of the spectra to determine in-cylinder gas temperature. The temperature results show that heat transfer effects can significantly bias thermometry when fiber-coupled engine probes are used. PMID:20820214

Rein, Keith D; Sanders,