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Sample records for quantitative uv-visible spectroscopy

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

    PubMed Central

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

    2009-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    1998-04-01

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

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

    PubMed

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

    2009-10-01

    The performance of an activated sludge reactor can be significantly enhanced through use of continuous and real-time process-state monitoring, which avoids the need to sample for off-line analysis and to use chemicals. Despite the complexity associated with wastewater treatment systems, spectroscopic methods coupled with chemometric tools have been shown to be powerful tools for bioprocess monitoring and control. Once implemented and optimized, these methods are fast, nondestructive, user friendly, and most importantly, they can be implemented in situ, permitting rapid inference of the process state at any moment. In this work, UV-visible and NIR spectroscopy were used to monitor an activated sludge reactor using in situ immersion probes connected to the respective analyzers by optical fibers. During the monitoring period, disturbances to the biological system were induced to test the ability of each spectroscopic method to detect the changes in the system. Calibration models based on partial least squares (PLS) regression were developed for three key process parameters, namely chemical oxygen demand (COD), nitrate concentration (N-NO(3)(-)), and total suspended solids (TSS). For NIR, the best results were achieved for TSS, with a relative error of 14.1% and a correlation coefficient of 0.91. The UV-visible technique gave similar results for the three parameters: an error of approximately 25% and correlation coefficients of approximately 0.82 for COD and TSS and 0.87 for N-NO(3)(-) . The results obtained demonstrate that both techniques are suitable for consideration as alternative methods for monitoring and controlling wastewater treatment processes, presenting clear advantages when compared with the reference methods for wastewater treatment process qualification. PMID:19701801

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

    PubMed

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

    2014-01-01

    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

  5. Quantitative analysis of surface amine groups on plasma-polymerized ethylenediamine films using UV visible spectroscopy compared to chemical derivatization with FT-IR spectroscopy, XPS and TOF-SIMS

    NASA Astrophysics Data System (ADS)

    Kim, Jinmo; Jung, Donggeun; Park, Yongsup; Kim, Yongki; Moon, Dae Won; Lee, Tae Geol

    2007-02-01

    A quantitative analysis of the surface density of amine groups on a plasma-polymerized ethylenediamine thin film deposited on a platinum surface using inductively coupled plasma chemical vapor deposition method is described. UV-visible spectroscopy together with a chemical derivatization technique using Fourier transform infrared (FT-IR) spectroscopy was used to obtain the quantitative information. Chemical tags of pentafluorobenzaldehyde were hybridized with the surface amine groups and were easily detected due to the characteristic absorption bands of C-F stretching, aromatic ring and C dbnd N stretching vibrations in the reflection-absorption FT-IR spectra. The surface amine density was reproducibly controlled as a function of deposition plasma power and quantified using UV-visible spectroscopy. A good linear correlation was observed between the FT-IR intensities of the characteristic absorption bands and the surface amine densities, suggesting the possibility of using this chemical derivatization technique to quantify the surface densities of specific functional groups on an organic surface. Chemical derivatization was also used with X-ray photoelectron spectroscopy on the same samples, and the results were compared with those obtained from FT-IR and time-of-flight secondary ion mass spectrometry. Although each analysis technique has different probing depths from the surface, the three different data sets obtained from the chemical tags correlated well with each other since each analysis technique measured the chemical tags on the sample surface.

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

    PubMed

    Sirajuddin, Muhammad; Ali, Saqib; Badshah, Amin

    2013-07-01

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

  7. Analysis of Fungal Pellets by UV-Visible Spectrum Diffuse Reflectance Spectroscopy

    PubMed Central

    Leštan, Domen; Podgornik, Helena; Perdih, Anton

    1993-01-01

    The application of the UV-visible spectrum diffuse reflectance spectroscopy for the determination of intracellular pH in vivo, for determination of cytochrome content, and for the noninvasive in vivo detection of the redox state of fungal mitochondrial cytochromes in filamentous fungi is introduced. The time course of the intracellular pH values, mitochondrial cytochromes, and CO-binding pigments content and the correlations between the actual redox state of cytochrome aa3 and saturation of growth medium with oxygen in pellets of the basidiomycete Phanerochaete chrysosporium were determined. As the test microorganism, the yeast Saccharomyces cerevisiae was used. UV-visible spectrum diffuse reflectance spectroscopy proved to be a promising method for the quick and simple analysis of light-impermeable biological structures for which the classical transmittance spectrophotometric methods are difficult to implement. PMID:16349122

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

    PubMed Central

    Agatonovic-Kustrin, Snezana; Morton, David W.

    2012-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Nonoyama, Akihisa

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

  10. Simple and Precise Quantification of Iron Catalyst Content in Carbon Nanotubes Using UV/Visible Spectroscopy

    PubMed Central

    Agustina, Elsye; Goak, Jeungchoon; Lee, Suntae; Seo, Youngho; Park, Jun-Young; Lee, Naesung

    2015-01-01

    Iron catalysts have been used widely for the mass production of carbon nanotubes (CNTs) with high yield. In this study, UV/visible spectroscopy was used to determine the Fe catalyst content in CNTs using a colorimetric technique. Fe ions in solution form red–orange complexes with 1,10-phenanthroline, producing an absorption peak at λ=510 nm, the intensity of which is proportional to the solution Fe concentration. A series of standard Fe solutions were formulated to establish the relationship between optical absorbance and Fe concentration. Many Fe catalysts were microscopically observed to be encased by graphitic layers, thus preventing their extraction. Fe catalyst dissolution from CNTs was investigated with various single and mixed acids, and Fe concentration was found to be highest with CNTs being held at reflux in HClO4/HNO3 and H2SO4/HNO3 mixtures. This novel colorimetric method to measure Fe concentrations by UV/Vis spectroscopy was validated by inductively coupled plasma optical emission spectroscopy, indicating its reliability and applicability to asses Fe content in CNTs. PMID:26491641

  11. UV-visible spectroscopy method for screening the chemical stability of potential antioxidants for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Banham, Dustin; Ye, Siyu; Knights, Shanna; Stewart, S. Michael; Wilson, Mahlon; Garzon, Fernando

    2015-05-01

    A novel method based on UV-visible spectroscopy is reported for screening the chemical stability of potential antioxidant additives for proton exchange membrane fuel cells, and the chemical stabilities of three CeOx samples of varying crystallite sizes (6, 13, or 25 nm) are examined. The chemical stabilities predicted by this new screening method are compared to in-situ membrane electrode assembly (MEA) accelerated stress testing, with the results confirming that this rapid and inexpensive method can be used to accurately predict performance impacts of antioxidants.

  12. Determination of pKa of felodipine using UV-Visible spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  13. Kinetic study on bonding reaction of gelatin with CdS nanopaticles by UV-visible spectroscopy

    NASA Astrophysics Data System (ADS)

    Tang, Shihua; Wang, Baiyang; Li, Youqun

    2015-04-01

    The chemical kinetics on gelatin-CdS direct conjugates has been systematically investigated as a function of different temperature and reactant concentration (i.e. Cd2+, S2- and gelatin) by UV-visible spectroscopy, for the first time. The nonlinear fitting and the differential method were used to calculate the initial rate based on the absorbance-time data. A double logarithmic linear equation for calculating the rate constant (k) and the reaction order (n) was introduced. The reaction kinetic parameters (n, k, Ea, and Z) and activation thermodynamic parameters (ΔG≠, ΔH≠, and ΔS≠) were obtained from variable temperature kinetic studies. The overall rate equation allowing evaluation of conditions that provide required reaction rate could be expressed as:

  14. Quantitation of cutaneous inflammation induced by reactive species generated by UV-visible irradiation of rose bengal

    SciTech Connect

    Ranadive, N.S.; Menon, I.A.; Shirwadkar, S.; Persad, S.D. )

    1989-10-01

    The present studies were undertaken to quantitate the initial inflammatory response produced by the photo-generated reactive species in rabbit skin. Rose bengal (RB), a photosensitizer dye, was injected into the skin sites at various concentrations and exposed to UV-visible light for 30-120 min. The increase in vascular permeability and the accumulation of PMNs were investigated using 125I-labeled albumin and 51Cr-labeled PMNs. RB at a concentration of 1 nmol with 120-min exposure to light enhanced vascular permeability by 3.7 times and accumulation of PMNs by 3.3 times. As low as 0.01 nmol of RB produced discernible effects. beta-Carotene (0.1 nmole) inhibited the inflammatory response by 75-100%, suggesting that the reactive species involved in this response was predominantly singlet oxygen. The increase in vascular permeability was inhibited by 48-70% by 25 micrograms of chlorpheniramine maleate. It is therefore suggested that histamine plays a major role in the initial vascular response. The studies demonstrate that this rabbit model is suitable for the quantitation of photoinduced inflammatory response which is not observable by gross anatomic procedures.

  15. In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

    PubMed

    Alin, Jonas; Rubino, Maria; Auras, Rafael

    2015-10-15

    UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. PMID:26122795

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

    SciTech Connect

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

    2001-01-01

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

  17. UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

    PubMed

    Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

    2016-01-01

    This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser. PMID:26740326

  18. [Raman spectroscopy applied to analytical quality control of injectable drugs: analytical evaluation and comparative economic versus HPLC and UV / visible-FTIR].

    PubMed

    Bourget, P; Amin, A; Vidal, F; Merlette, C; Troude, P; Corriol, O

    2013-09-01

    In France, central IV admixture of chemotherapy (CT) treatments at the hospital is now required by law. We have previously shown that the shaping of Therapeutic Objects (TOs) could profit from an Analytical Quality Assurance (AQA), closely linked to the batch release, for the three key parameters: identity, purity, and initial concentration of the compound of interest. In the course of recent and diversified works, we showed the technical superiority of non-intrusive Raman Spectroscopy (RS) vs. any other analytical option and, especially for both HPLC and vibrational method using a UV/visible-FTIR coupling. An interconnected qualitative and economic assessment strongly helps to enrich these relevant works. The study compares in operational situation, the performance of three analytical methods used for the AQC of TOs. We used: a) a set of evaluation criteria, b) the depreciation tables of the machinery, c) the cost of disposables, d) the weight of equipment and technical installations, e) the basic accounting unit (unit of work) and its composite costs (Euros), which vary according to the technical options, the weight of both human resources and disposables; finally, different combinations are described. So, the unit of work can take 12 different values between 1 and 5.5 Euros, and we provide various recommendations. A qualitative evaluation grid constantly places the SR technology as superior or equal to the 2 other techniques currently available. Our results demonstrated: a) the major interest of the non-intrusive AQC performed by RS, especially when it is not possible to analyze a TO with existing methods e.g. elastomeric portable pumps, and b) the high potential for this technique to be a strong contributor to the security of the medication circuit, and to fight the iatrogenic effects of drugs especially in the hospital. It also contributes to the protection of all actors in healthcare and of their working environment. PMID:24804411

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  2. [Determination of Trace Lead in Water by UV-Visible Diffuse Reflectance Spectroscopy Combined with Surfactant and Membrane Filtration-Enrichment].

    PubMed

    Zhang, Xiao-fang; Zhu, Bi-lin; Li, Wei; Wang, Lei; Zhang, Lei; Wu, Ting; Du, Yi-ping

    2015-07-01

    In this paper, a method of determination of trace lead in water by UV-Visible diffuse reflectance spectroscopy combined with surfactant and membrane filtration enrichment was proposed. In the NH3 x H2O-NH4Cl buffer solution with pH 8.5, the lead(II) ion would react with dithizone to form the red complex under vigorous stirring, which is hydrophobic and can be enriched by the mixed cellulose ester membrane. In addition, the nonionic surfactant Polyoxyethylene lauryl ether (Brij-30) was added into the solution to improve the enrichment efficiency, then visible diffuse reflectance spectra of the membrane were measured directly after the membrane were naturally dried. We also optimized the reaction conditions which may affect the complexation reaction process, such as type of surfactants, the concentration of the surfactant, the reaction acidity, the concentration of dithizone as well as the reaction time. The research results show that under the optimum conditions, a good linear correlation between absorbance at 485 nm and concentration of lead in the range of 5.0-100.0 microg x L(-1) was obtained with a squared correlation coefficient (R2) of 0.9906, and the detection limit was estimated accordingly to be 2.88 microg x L(-1). To determine real water sample, the interference from some potential coexisting ions was also studied at the optimal conditions when the concentration of lead (II) ion standard solution was fixed to 20 microg x L(-1). The results indicate that the following ions cannot interfere in the determination of lead with the proposed method: 500 times of the K+, Na+, Ca2+, Mg2+, NH4+, NO3-, Cl-, CH3COO-, SO4(2-); 10 times of the Al3+ (using 10% NaF as a masking reagent to avoid the interference); 10 times of the Fe3+ (using 10% NaF and 10% sodium potassium tartrate as masking reagents); 10 times of Hg2+ or Zn2+ (using 10% NaSCN and 10% potassium sodium tartrate as masking reagents); the same amount of Cd2+, Cu2+. The proposed method was applied to the determnation of lead (II) in bottled water as a real sample. The determination results show good agreements between the proposed method and graphite furnace atomic absorption spectrometry (GFAAS) method. The recoveries in case of spiked real samples were between 95.4% and 104.5%, and the standard deviations (SD) were between 0.5 micro x L(-1) and 1.5 microg x L(-1), which indicate that the method developed in the present work with advantages of accuracy, simpleness, sensitiveness are of potential application for the determination of trace lead in water samples. PMID:26717757

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  4. Towards a semiquantitative non invasive characterisation of Tyrian purple dye composition: Convergence of UV-Visible reflectance spectroscopy and fast-high temperature-high performance liquid chromatography with photodiode array detection.

    PubMed

    Clementi, Catia; Nowik, Witold; Romani, Aldo; Cardon, Dominique; Trojanowicz, Marek; Davantès, Athénaïs; Chaminade, Pierre

    2016-07-01

    In this paper, partial least square (PLS) regression is innovatively applied for a semi-quantitative non invasive study of the most precious dye of Antiquity: Tyrian purple. This original approach for the study of organic dyes in the cultural heritage field, is based on the correlation of spectrophotometric (UV-Visible) and chromatographic (Fast-HT-HPLC-PDA) data from an extensive set of textiles prepared with different snail species according to historical recipes. A cross-validated PLS model, based on the quantity of 6,6'-dibromoindigotin, displays an excellent correlation factor (R(2)Y = 0.987) between values determined by chromatography and those predicted from reflectance spectra. This indicates that the spectral features of Tyrian purple on textile fibre is strictly related to the amount of this indigoid component whose content may be non invasively predicted from reflectance spectrum. The studied correlation also highlights that, independently of the dyeing method and nature of the textile fibre used, the relative content of 6,6'-dibromindigotin may be used as a parameter to distinguish samples prepared with Hexaplex trunculus L. snails from those prepared with further mollusc species. To validate this model, archaeological textile fragments dating from the Roman period were successfully examined. The results achieved open an absolutely new way in Tyrian purple analysis in cultural heritage by non invasive spectroscopic techniques attesting their convergence with HPLC and giving them a semi-quantitative value. PMID:27216389

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

    PubMed Central

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

    2014-01-01

    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

  6. Optical constants and band gap determination of Pb0.95La0.05Zr0.54Ti0.46O3 thin films using spectroscopic ellipsometry and UV-visible spectroscopy

    NASA Astrophysics Data System (ADS)

    Batra, Vaishali; Kotru, Sushma; Varagas, M.; Ramana, C. V.

    2015-11-01

    We report the structural evolution and optical properties of lanthanum doped lead zirconate titanate (PLZT) thin films prepared on Pt/TiO2/SiO2/Si substrates by chemical solution deposition. X-ray diffraction demonstrates the post-deposition annealing induced crystallization for PLZT films annealed in a temperature (Ta) range of 550-750 °C. PLZT films annealed at higher temperature exhibit polycrystalline structure along with larger grain size. Optical band gap (Eg) values determined from UV-visible spectroscopy and spectroscopic ellipsometry (SE) for PLZT films were found to be in the range of 3.5-3.8 eV. Eg decreases with increasing Ta. The optical constants and their dispersion profiles for PLZT films were also determined from SE analyses. PLZT films show an index of refraction in the range of 2.46-2.50 (λ = 632.8 nm) with increase in Ta. The increase in refractive index at higher Ta is attributed to the improved packing density and crystallinity with the temperature.

  7. On the formation of new reverse micelles: a comparative study of benzene/surfactants/ionic liquids systems using UV-visible absorption spectroscopy and dynamic light scattering.

    PubMed

    Falcone, R Darío; Correa, N Mariano; Silber, Juana J

    2009-09-15

    The microenvironment of the polar core generated in different ionic liquid reverse micelle (IL RM) systems were investigated using the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as an absorption probe and dynamic light scattering (DLS) technique. The novel RM systems consist of two different ILs--1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf2N)--sequestrated by two different surfactants--Triton X-100 (TX-100) and benzyl-n-hexadecyldimethylammonium chloride (BHDC)--in order to make IL/surfactant/benzene RMs. The effect of the variation of Ws (Ws=[IL]/[surfactant]) on the QB spectroscopy was used to characterize these nonaqueous RMs. DLS results confirm the formation of these IL RM systems because increasing Ws increases the droplet sizes. Moreover it is demonstrated that the structure of the sequestrated ILs depends strongly on the type of surfactant use to create the RMs. PMID:19678620

  8. 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)

    Climent, Miguel A.; Gutirrez, Claudio

    1995-06-01

    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.

  9. A screening method based on UV-Visible spectroscopy and multivariate analysis to assess addition of filler juices and water to pomegranate juices.

    PubMed

    Boggia, Raffaella; Casolino, Maria Chiara; Hysenaj, Vilma; Oliveri, Paolo; Zunin, Paola

    2013-10-15

    Consumer demand for pomegranate juice has considerably grown, during the last years, for its potential health benefits. Since it is an expensive functional food, cheaper fruit juices addition (i.e., grape and apple juices) or its simple dilution, or polyphenols subtraction are deceptively used. At present, time-consuming analyses are used to control the quality of this product. Furthermore these analyses are expensive and require well-trained analysts. Thus, the purpose of this study was to propose a high-speed and easy-to-use shortcut. Based on UV-VIS spectroscopy and chemometrics, a screening method is proposed to quickly screening some common fillers of pomegranate juice that could decrease the antiradical scavenging capacity of pure products. The analytical method was applied to laboratory prepared juices, to commercial juices and to representative experimental mixtures at different levels of water and filler juices. The outcomes were evaluated by means of multivariate exploratory analysis. The results indicate that the proposed strategy can be a useful screening tool to assess addition of filler juices and water to pomegranate juices. PMID:23692760

  10. UV/Visible Telescope with Hubble Disposal

    NASA Technical Reports Server (NTRS)

    Benford, Dominic J.

    2013-01-01

    Submission Overview: Our primary objective is to convey a sense of the significant advances possible in astrophysics investigations for major Cosmic Origins COR program goals with a 2.4m telescope asset outfitted with one or more advanced UV visible instruments. Several compelling science objectives were identified based on community meetings these science objectives drove the conceptual design of instruments studied by the COR Program Office during July September 2012. This RFI submission encapsulates the results of that study, and suggests that a more detailed look into the instrument suite should be conducted to prove viability and affordability to support the demonstrated scientific value. This study was conducted in the context of a larger effort to consider the options available for a mission to dispose safely of Hubble hence, the overall architecture considered for the mission we studied for the 2.4m telescope asset included resource sharing. This mitigates combined cost and risk and provides naturally for a continued US leadership role in astrophysics with an advanced, general-purpose UV visible space telescope.

  11. Quantitative phase spectroscopy

    PubMed Central

    Rinehart, Matthew; Zhu, Yizheng; Wax, Adam

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  13. Quantitative velocity modulation spectroscopy

    NASA Astrophysics Data System (ADS)

    Hodges, James N.; McCall, Benjamin J.

    2016-05-01

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.

  14. Simultaneous infrared and UV-visible absorption spectra of matrix-isolated carbon vapor

    NASA Technical Reports Server (NTRS)

    Kurtz, Joe; Huffman, Donald R.

    1989-01-01

    Carbon molecules were suggested as possible carriers of the diffuse interstellar bands. In particular, it was proposed that the 443 nm diffuse interstellar band is due to the same molecule which gives rise to the 447 nm absorption feature in argon matrix-isolated carbon vapor. If so, then an associated C-C stretching mode should be seen in the IR. By doing spectroscopy in both the IR and UV-visible regions on the same sample, the present work provides evidence for correlating UV-visible absorption features with those found in the IR. Early data indicates no correlation between the strongest IR feature (1997/cm) and the 447 nm band. Correlation with weaker IR features is being investigated.

  15. Effet de la polarité du solvant sur les propriétés des états électroniques excités du 1,1'-binaphtyle: étude par spectroscopie UV-visible

    NASA Astrophysics Data System (ADS)

    Benali, B.; Fadouach, M.; Kabouchi, B.; Kadiri, A.; Nouchi, G.

    1993-07-01

    A UV-vis emission spectroscopy study of the flexible molecule, 1,1'-binaphtyl as a function of solvent polarity allows one to obtain information on the excited singlet states. We show the existence of a charge transfer (CT) character state. This CT is evidenced by the solvent polarity effect, the measurement of polarization ratio and finally by comparison of the ratio intensities of phosphorescence and fluorescence.

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

    NASA Astrophysics Data System (ADS)

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

    2005-06-01

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

  17. 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

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

    2015-01-01

    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

  18. Quantitative Spectroscopy of Deneb

    NASA Astrophysics Data System (ADS)

    Schiller, Florian; Przybilla, N.

    We use the visually brightest A-type supergiant Deneb (A2 Ia) as benchmark for testing a spectro- scopic analysis technique developed for quantitative studies of BA-type supergiants. Our NLTE spectrum synthesis technique allows us to derive stellar parameters and elemental abundances with unprecedented accuracy. The study is based on a high-resolution and high-S/N spectrum obtained with the Echelle spectrograph FOCES on the Calar Alto 2.2 m telescope. Practically all inconsistencies reported in earlier studies are resolved. A self-consistent view of Deneb is thus obtained, allowing us to discuss its evolutionary state in detail by comparison with the most recent generation of evolution models for massive stars. The basic atmospheric parameters Teff = 8525 ± 75 K and log g = 1.10 ± 0.05 dex (cgs) and the distance imply the following fundamental parameters for Deneb: M spec = 17 ± 3 M⊙ , L = 1.77 ± 0.29 · 105 L⊙ and R = 192 ± 16 R⊙ . The derived He and CNO abundances indicate mixing with nuclear processed matter. The high N/C ratio of 4.64 ± 1.39 and a N/O ratio of 0.88 ± 0.07 (mass fractions) could in principle be explained by evolutionary models with initially very rapid rotation. A mass of ˜ 22 M⊙ is implied for the progenitor on the zero-age main se- quence, i.e. it was a late O-type star. Significant mass-loss has occurred, probably enhanced by pronounced centrifugal forces. The observational constraints favour a scenario for the evolu- tion of Deneb where the effects of rotational mixing may be amplified by an interaction with a magnetic field. Analogous analyses of such highly luminous BA-type supergiants will allow for precision studies of different galaxies in the Local Group and beyond.

  19. A Quantitative Infrared Spectroscopy Experiment.

    ERIC Educational Resources Information Center

    Krahling, Mark D.; Eliason, Robert

    1985-01-01

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

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

    SciTech Connect

    Ken Czerwinski; Phil Weck; Frederic Poineau

    2010-12-29

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

  1. Synchrotron UV-visible multispectral luminescence microimaging of historical samples.

    PubMed

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

    2011-03-01

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

  2. UV/visible camera for the Clementine mission

    SciTech Connect

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

    1995-04-01

    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.

  3. [Authentication of Age of Bloodstains Using UV Visible Reflection Spectrum].

    PubMed

    Gao, Qian-yu; Gao, Shi-ming

    2015-08-01

    The age of bloodstains is tightly related to the time elapsed since the crime was committed. The inference of the time that the crime was committed is of great significance to solve the case, and it was also a difficult problem in judicial authentication. Therefore, establishing a method of rapid determination of bleeding time is very necessary. Using a UV-visible spectrometer with a reflection accessory called ISR-240A and whiteboard as a reference standard, the reflection spectra of blood gauze, aluminum, glass and plastic were measured every hour under the condition of 16 °C and 70% humidity within 8 hours. Using SPSS to process the data, R541/R577 was figured out and linear fitting was completed. The same method was carried on on the gauze of blood at 24 °C. The results showed that, within 8 hours, spectral reflectance values of blood at 541 and 577 nm increased gradually with the passage of injury time. In addition to the R2 of the glass with blood is 0.769, the rest of the R2 were greater than 0.900. The values of F were greater than F0.05 (1, 6) = 5.59. Therefore, the linear regression model is significant meaningful. The method of using a UV-Visible spectrometer without doing any operations of the test samples is simple. Moreover, it does no harm to the further inspection in aspects of personal information, which is suitable for the judicial practice. PMID:26672298

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    SciTech Connect

    Czerwinski, Kenneth; Weck, Phil

    2013-09-13

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

  7. Ozone Profile Retrievals from GOME-2 UV/Visible Measurements

    NASA Astrophysics Data System (ADS)

    Liu, X.; Zoogman, P.; Chance, K.; Nowlan, C. R.

    2014-12-01

    It has been shown that adding visible measurements in the Chappuis band to ultraviolet (UV) measurements in the Hartley/Huggins bands can significantly enhance retrieval sensitivity to lower tropospheric ozone from backscattered solar radiances due to deeper photon penetration in the visible to the surface than in the ultraviolet. The first NASA Eearth Venture Instrument TEMPO (Tropospheric Emissions: Monitoring of Pollution) instrument is being developed to measure backscattered solar radiation in two channels (~290-490 and 540-740 nm) and make atmospheric pollution measurements over North America from the Geostationary orbit; the primary purpose of including the second channel is to improve lower tropospheric ozone retrieval for air quality monitoring. However, this retrieval enhancement has yet to be solidly demonstrated from existing measurements due to the weak ozone absorption in the visible and strong interference from surface reflectance. We present retrievals from GOME-2 (Global Ozone Monitoring and Experiment-2) UV and visible measurements using the SAO optimal estimation based ozone profile retrieval algorithm, to directly explore the retrieval improvement in lower tropospheric ozone from additional visible measurements. To reduce the retrieval interference from surface reflectance, we add characterization of surface spectral reflectance in the visible into the ozone profile algorithm based on existing surface reflectance spectra and MODIS (Moderate-resolution Imaging Spectroradiometer) BRDF (Bidirectional Reflectance Distribution Function) climatology. We evaluate the retrieval performance of UV/visible retrieval over the UV retrieval in terms of retrieved lower tropospheric ozone and increase in degree of free for signal (DFS) over the globe in different seasons, and we validate both retrievals against ozonesonde measurements.

  8. 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...

  9. Monitoring of Laser Material Welding Process Using UV-Visible Spectrometer

    SciTech Connect

    Genc, B.; Kacar, E.; Akman, E.; Demir, A.

    2007-04-23

    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.

  10. Quantifying the relationship between the measurement precision and specifications of a UV/visible sensor on a geostationary satellite

    NASA Astrophysics Data System (ADS)

    Irie, Hitoshi; Iwabuchi, Hironobu; Noguchi, Katsuyuki; Kasai, Yasuko; Kita, Kazuyuki; Akimoto, Hajime

    2012-06-01

    To investigate the feasibility of new satellite observations, including air quality (AQ) observations from geostationary (GEO) orbit, it is essential to link the measurement precision (ɛ) with sensor specifications in advance. The present study attempts to formulate the linkage between ɛ and specifications of a UV/visible sensor (signal-to-noise ratio (SNR), full width at half maximum (FWHM) of the slit function, and sampling ratio (SR)) on a GEO satellite. A sophisticated radiative transfer model (JACOSPAR) is used to calculate synthetic radiance spectra that would be measured by a UV/visible sensor observing the atmosphere over Tokyo (35.7°N, 139.7°E) from GEO orbit at 120°E longitude. The spectra, modified according to given sensor specifications, are analyzed by the differential optical absorption spectroscopy technique to estimate the ɛ for slant column densities of O3 and NO2. We find clear relationships: for example, the ɛ of the O3 slant column density (molecules cm-2) and SNR at 330 nm are linked by the equation log(ɛ) = -1.06 · log(SNR) + 20.71 in the UV region, and the ɛ of the NO2 slant column density and SNR at 450 nm are linked by log(ɛ) = -0.98 · log(SNR) + 18.00, at a FWHM = 0.6 nm (for the Gaussian slit function) and SR = 4. The relationships are mostly independent of other specifications (e.g., horizontal and temporal resolutions), as they affect ɛ primarily through SNR, providing constraints in determining the optimal SNR (and alternatively FWHM and SR) for similar UV/visible sensors dedicated for AQ studies.

  11. Quantitative tunneling spectroscopy of nanocrystals

    SciTech Connect

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

    2007-05-25

    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

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

    SciTech Connect

    Egan, William; Morgan, Stephen L. Brewer, William E.

    1999-02-01

    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}

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  14. Non-contact quantitative diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Sorgato, Veronica; Berger, Michel; Emain, Charlotte; Koenig, Anne; Roig, Blandine; Vever-Bizet, Christine; Dinten, Jean-Marc; Bourg-Heckly, Geneviève; Planat-Chrétien, Anne

    2015-07-01

    We validate a non-contact Diffuse Reflectance Spectroscopy (DRS) system as a first stage to approach quantitative multi-spectral imaging technique. The non-contact DRS system with separated illumination and detection paths was developed with different progressive set-ups which were all compared to a well-founded contact DRS system. While quantitation of the absorption coefficient is well achieved with the existing method, the calculation of the scattering coefficient is deteriorated by the non-contact architecture measurements. We have therefore developed an adaptive reference-based algorithm to compensate for this effect.

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

    NASA Astrophysics Data System (ADS)

    Rahmalia, Winda; Fabre, Jean-Franois; Usman, Thamrin; Mouloungui, Zphirin

    2014-10-01

    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.

  16. Inorganic UV-Visible-SWIR Broadband Photodetector Based on Monodisperse PbS Nanocrystals.

    PubMed

    Lee, Jae Woong; Kim, Do Young; Baek, Sujin; Yu, Hyeonggeun; So, Franky

    2016-03-01

    Solution-processed inorganic UV-visible short-wave-infrared photodetectors with light sensitivity from 350 nm to 2000 nm are fabricated using highly monodispersed large PbS NCs. These devices showed detectivity values over 1 × 10(11) Jones from 350 nm to 2000 nm, and a maximum detectivity value of 1.2 × 10(12) Jones at 1800 nm. PMID:26763178

  17. Piezo-phototronic UV/visible photosensing with optical-fiber-nanowire hybridized structures.

    PubMed

    Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Liu, Ying; Ding, Yong; Wang, Zhong Lin

    2015-03-01

    An optical-fiber-nanowire hybridized UV-visible photodetector (PD) is reported. The PD is designed to allow direct integration in optical communication systems without requiring the use of couplers via fiber-welding technology. The PD works in two modes: axial and off-axial illumination mode. By using the piezo-phototronic effect, the performance of the PD is enhanced/optimized by up to 718% in sensitivity and 2067% in photoresponsivity. PMID:25589428

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

    PubMed

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

    2014-10-01

    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

  19. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    ERIC Educational Resources Information Center

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  20. 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)

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

    2005-06-01

    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.

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

    PubMed

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

    2014-10-15

    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 λmax 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

  2. Quantitative atomic spectroscopy for primary thermometry

    SciTech Connect

    Truong, Gar-Wing; Luiten, Andre N.; May, Eric F.; Stace, Thomas M.

    2011-03-15

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

  3. Infrared quantitative spectroscopy and planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Flaud, J.-M.

    2009-04-01

    Optical measurements of atmospheric minor constituents are carried out using spectrometers working in the UV-visible, infrared and microwave spectral ranges. In all cases the quality of the analysis and of the interpretation of the atmospheric spectra requires the best possible knowledge of the molecular parameters of the species of interest. To illustrate this point we will concentrate on recent laboratory studies of nitric acid, chlorine nitrate and formaldehyde. Nitric acid is one of the important minor constituent of the terrestrial atmosphere. Using new and accurate experimental results concerning the spectroscopic properties of the H14NO3 and H15NO3 molecules, as well as improved theoretical methods (Perrin et al., 2004), it has been possible to generate an improved set of line parameters for these molecules in the 11.2 μm spectral region. These line parameters were used to detect for the first time the H15NO3 molecule in the atmosphere analyzing atmospheric spectra recorded by the MIPAS experiment. The retrievals of chlorine nitrate profiles are usually performed using absorption cross sections (Birk and Wagner, 2003). Following a high resolution analysis of the ν3 and ν4bands of this species in the 12.8 μm region wepropose, as a possibility, to use line by line calculation simulating its ν4Q-branch for the atmospheric temperature and pressure ranges. For the measurement of atmospheric formaldehyde concentrations, mid-infrared and ultraviolet absorptions are both used by ground, air or satellite instruments. It is then of the utmost importance to have consistent spectral parameters in these various spectral domains. Consequently the aim of the study performed at LISA (Gratien et al., 2007) was to intercalibrate formaldehyde spectra in the infrared and ultraviolet regions acquiring simultaneously UV and IR spectra using a common optical cell. The results of the work will be presented. Also high resolution infrared data derived from Perrin et al., 2003 have been used to determine vertical distributions from the upper troposphere to the stratopause using the high spectral resolution measurements of MIPAS (Steck et al., 2008). References: M. Birk, G. Wagner, J. Quant. Spectros. Radiat.Transfer, 82, 443, 2003. G. Brizzi, M. Carlotti, J.-M. Flaud, A. Perrin and M. Ridolfi, Geophys. Res. Lett., 34, L03802, 2006. A. Gratien, B. Picquet-Varrault, J. Orphal, E. Perraudin, J.-F. Doussin and J.-M. Flaud, J. Geophys. Res., 112, D05305, 2007. A. Perrin, F. Keller and J.-M. Flaud, J. Mol. Spectrosc., 221, 192, 2003. A. Perrin, J. Orphal, J.-M. Flaud, S. Klee, G. Mellau, H. Mader, D. Walbrodt and M. Winnewisser, J. Mol. Spectrosc, 228, 375, 2004. T. Steck, N. Glatthor, T. von Clarmann, H. Fischer, J. M. Flaud, B. Funke, U. Grabowski, M. Hopfner, S. Kellmann, A. Linden, A. Perrin, and G. P. Stiller, Atm. Chem. Phys., 8, 463, 2008.

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

  5. UV-visible spectroscopy of organic carbon particulate sampled from ethylene/air flames.

    PubMed

    Sgro, L A; Minutolo, P; Basile, G; D'Alessio, A

    2001-01-01

    A systematic comparison of spectra obtained with extra and in situ diagnostics in the soot preinception region of rich, premixed ethylene air flames suggests that combustion generated organic carbon (OC) particulate can be extracted from flames and isolated from other flame material for further chemical analysis. Both the trend with height above the burner and the form of UV fluorescence and absorption spectra from extra situ sampled material captured in water agree with those measured in situ. These results show that the OC particulate formed in flames is partially water soluble. However, the collection efficiency can be increased using less polar solvents, like acetonitrile and dichloromethane. The fluorescence spectra from the water samples are comprised both a naphthalene-like component and a broad band UV fluorescence component similar to that observed in situ which is attributed to flame generated OC particulate. The broad band UV fluorescence centered around 320 nm is also observed very early in flames and does not change considerably with increasing flame residence time. These results support previous hypotheses that the UV broad band fluorescence is from carbonaceous material comprised two-ring aromatics, formed earlier than soot in the flame, and is still present along with soot at higher heights or flame residence times. PMID:11219693

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

    EPA Science Inventory

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

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  9. UV-visible luminescence properties of the broad-band Yb:CALGO laser crystal

    NASA Astrophysics Data System (ADS)

    Jaffres, A.; Sharma, S. K.; Loiseau, P.; Viana, B.; Doualan, J. L.; Moncorgé, R.

    2015-03-01

    Yb:CALGO is now recognized to exhibit outstanding properties for the production of high-power and ultra-short laser pulses in the near infrared spectral range. However, various UV-visible absorption bands can be also observed due to different types of charge transfer mechanisms. Some of them are assigned to the formation of color centers due to small polarons and others to O2-→Yb3+ ligand-to-metal charge transfer (LMCT) transitions. The former can be removed by using adequate thermal treatments. The latter are intrinsic and they are very intense with cross sections of about two orders of magnitude larger that the near infrared ones. In fact, such LMCT absorption bands are responsible for relatively large changes of ionic polarizabilities and to non-negligible pseudo-nonlinear changes of refractive indices which should certainly affect the laser properties of Yb:CALGO at high pump power levels.

  10. Required Technologies for A 10-16 m UV-Visible-IR Telescope on the Moon

    NASA Technical Reports Server (NTRS)

    Johnson, Stewart W.; Wetzel, John P.

    1989-01-01

    A successor to the Hubble Space Telescope, incorporating a 10 to 16 meter mirror, and operating in the UV-Visible-IR is being considered for emplacement on the Moon in the 21st Century. To take advantage of the characteristics of the lunar environment, such a telescope requires appropriate advances in technology. These technologies are in the areas of contamination/interference control, test and evaluation, manufacturing, construction, autonomous operations and maintenance, power and heating/cooling, stable precision structures, optics, parabolic antennas, and communications/control. This telescope for the lunar surface needs to be engineered to operate for long periods with minimal intervention by humans or robots. What is essential for lunar observatory operation is enforcement of a systems engineering approach that makes compatible all lunar operations associated with habitation, resource development, and science.

  11. Statistical analysis of the impact of spectral correlation on observed formation constants from UV-visible spectroscopic measurements.

    PubMed

    Meinrath, Günther; Lis, Stefan; Piskula, Zbigniew

    2004-01-01

    Information retrieved from UV-visible spectroscopic data by application of a self-modelling factor analysis algorithm showed apparently systematically shifted thermodynamic properties for the same chemical system as a function of spectral slit widths. This empirical observation triggered a systematic investigation into the likely effects of residual and spectral correlation on the numerical results from quantitative spectroscopic investigations. If slit width was a nuisance factor it would reduce the comparability of information evaluated from spectroscopic data. The influence of spectral slit width was investigated by simulation, i.e. by generating and evaluating synthetic spectra with known properties. The simulations showed that increasing spectral correlation may introduce bias into factor analysis evaluations. By evaluation of the complete measurement uncertainty budget using threshold bootstrap target factor (TB CAT) analysis, the apparent shifts are insignificant relative to the total width of the quantity's measurement uncertainty. Increasing the slit widths causes some systematic effects, for example broadening of the registered spectral bands and reduction of spectral noise, because of higher light intensity passing to the detector. Hence, the observed systematic shifts in mean values might be caused by some latent correlation. As a general conclusion, slit width does not affect bias. However, the simulations show that spectral correlation and residual correlation may cause bias. Residual correlation can be taken into account by computer-intensive statistical methods, for example moving block or threshold bootstrap analysis. Spectral correlation is a property of the chemical system under study and cannot be manipulated. As a major result, evidence is given showing that stronger spectral correlation ( r<-0.7) causes non-negligible bias in the evaluated thermodynamic information from such a system. PMID:14615865

  12. Characterization of a polarization-resolved high spectral resolution UV-visible spectrometer

    NASA Astrophysics Data System (ADS)

    Kim, J.; Kim, D.

    2008-03-01

    To measure the degree of polarization of a plasma emission, a polarization-resolved UV-visible Czerny-Turner-type spectrometer was designed and constructed. For a high spectral resolution, F =1m mirrors were used as a focusing and collimating mirrors and the incidence angles to the mirrors were determined to eliminate coma. The effect of astigmatism was reduced by designing the incidence angles to the mirrors to be as small as possible. The flat focal plane condition proposed by Reader [J. Opt. Soc. Am. 59, 1189 (1969)] was used to determine the grating position. The measured spatial resolution was 170μm. To simultaneously measure the intensities with two perpendicular polarizations, a calcite crystal was placed after the entrance slit of the spectrometer. The change in the imaging property of the spectrometer due to the calcite crystal was measured and minimized. The spectral resolution was experimentally measured with a laser produced plasma to be 0.05nm at 348nm. The resolving power measured is 6600.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg

    2000-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  18. Spatially resolved quantitative spectroscopy of comets

    NASA Technical Reports Server (NTRS)

    Spinrad, Hyron

    1988-01-01

    Because of their temporal and spatial variations, modern ground-based studies of comets within approximately 4 A.U. of the sun are observationally demanding tasks. Over the years, researchers have attempted resolved spectroscopy of comets covering a wide range of intrinsic luminosity. Recently this group has developed spectral and direct-imaging procedures to detect weak ion tails submerged into the comae of even fairly faint comets. Although the last year was devoid of any really bright comet, re-analysis of older dust and gas production data of the 1986 P/Halley apparition has been almost completed. The main changes are that the nucleus does make a significant contribution to continuum light, and that the gravity effect in the dust escape velocity is somewhat larger than previously assumed. On the direct observational side, spectral studies of the 1987's Comet Bradfield show it to be qualitatively carbon-rich, at least in the outer coma ratio of CO(+) and CO2(+), compared the H2O(+) with respect to Halley at similar heliocentric distances.

  19. Photodetectors: Inorganic UV-Visible-SWIR Broadband Photodetector Based on Monodisperse PbS Nanocrystals (Small 10/2016).

    PubMed

    Lee, Jae Woong; Kim, Do Young; Baek, Sujin; Yu, Hyeonggeun; So, Franky

    2016-03-01

    Synthesis of highly mono-dispersed large PbS nanocrystals (NCs) with low particle size dispersion is demonstrated by F. So and co-workers on page 1328, by controlling the sulfur concentration below the nucleation threshold during multiple injections of the sulfur precursor. These NCs are used to fabricate multi-spectral photodetectors and high detectivity values in the UV-Visible-SWIR (short-wave-IR) wavelength range from 350 nm to 2000 nm are demonstrated. PMID:26948839

  20. UV-Visible Spectrooelectrochemistry of the Reduction Products of Anthraquinone in Dimethylformamide Solutions: An Advanced Undergraduate Experiment

    NASA Astrophysics Data System (ADS)

    Babaei, Ali; Connor, Paul A.; McQuillan, A. James; Umapathy, Siva

    1997-10-01

    The redox properties of anthraquinone (AQ) may be used to model the behaviour of quinones in biological systems. AQ undergoes two successive one-electron reductions in aprotic solvents to form a stable radical anion (AQ.-) and a stable dianion (AQ2-) but this behaviour is altered in the presence of a proton donor. This advanced undergraduate experiment shows how cyclic voltammetry, digital simulations of cyclic voltammograms, and UV-visible spectroelectrochemistry may be used to examine the reduction behaviour of AQ in dimethylformamide (DMF), both in the absence and presence of benzoic acid. The cyclic voltammetry of AQ in DMF shows two reversible one-electron reductions. This allows the UV-visible spectra of AQ.- and of AQ2- to be determined using an optically transparent thin layer electrode (OTTLE) cell. AQH- may also be detected in the spectra if there are proton impurities. When benzoic acid is added to the DMF, the cyclic voltammograms are markedly altered with almost all the reduction occurring near the AQ/AQ.- potential and the corresponding oxidation at rather more positive potentials. The UV-visible spectroelectrochemistry shows AQH2 as the stable reduction product under these conditions while digital simulations of the cyclic voltammograms support a mechanism involving protonation of AQ.- followed by AQH. disproportionation.

  1. Compressed Cu[sup 2+] ions in a Bi[sub 4]V[sub 2]O[sub 11] oxide matrix. 1. EPR and UV-visible study

    SciTech Connect

    Aboukais, A.; Delmaire, F.; Rigole, M.; Hubaut, R.; Mairesse, G.

    1993-12-01

    BICUVOX.x (Bi[sub 2]V[sub 1-x]Cu[sub x]O[sub 5.5-1.5x]) prepared with different atomic ratios Cu/V and calcined under a dry air at 1093 K have been characterized by electron paramagnetic resonance (EPR). The inverted g anisotropy values of the copper(II) ions EPR signal (g[sub perpendicular] > g[sub parallel]) can be interpreted by an octahedral symmetry strongly distorted with a compression of oxygen atoms along the apical direction. These results have been confirmed by UV-visible spectroscopy. 29 refs., 4 figs., 1 tab.

  2. CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: QA TESTS, QUANTITATION AND SPECTROSCOPY

    EPA Science Inventory

    Confocal Microscopy System Performance: QA tests, Quantitation and Spectroscopy.

    Robert M. Zucker 1 and Jeremy M. Lerner 2,
    1Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research Development, U.S. Environmen...

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Shukla, Madhulata; Srivastava, Nitin; Saha, Satyen

    2012-08-01

    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 π-π* transition in the chloranil is also observed.

  5. Design of a helix-bundle cross-link: NMR and UV-visible spectroscopic analyses and molecular modeling of ring-oxidized retinals.

    PubMed

    Williams, T C; Mani, V

    1991-03-19

    In order to generate potential chemical cross-links for studying the chromophore binding site of bacteriorhodopsin and related helix-bundle proteins, MnO2 was used to oxidize all-trans-retinal's ring moiety. The structures and solution conformations of three ring-oxidized retinal analogues have been determined by using UV-visible absorption and 1H and 13C NMR spectroscopies, primarily with regard to (i) the introduction of a functional group at the ring end of the chromophore, (ii) the retention of the all-trans geometry of the polyenal side chain, and (iii) the torsional angle of the ring-polyenal bond. Analyses of their UV-visible absorption spectral parameters (lambda max, epsilon max, and vibrational fine structure) and NMR spectral parameters (1H-1H coupling constants, 1H and 13C NMR chemical shifts, and 1H homonuclear Overhauser effects) indicated the 4-oxo and the 2,3-dehydro-4-oxo derivatives both possess the twisted 6-s-cis conformation adopted by most six-membered ring analogues of retinal in solution or crystal. However, the alpha-dioxocyclopentenyl analogue exists in solution predominantly (70-80%) as the planar 6-s-trans conformer, similar to violerythrine chromophore analogues. In order to identify the minor solution forms, molecular modeling and geometry optimizations using the semiempirical molecular orbital method AM1 defined two additional symmetry-related minima at +/- 30-40 degrees in its C6-C7 torsional energy profile. Because the chromophores of bacterio- and halorhodopsins and sensory rhodopsins are bound as the 6-s-trans conformer [Harbison, G.S., Smith, S.O., Pardoen, J.A., Courtin, J.M.L., Lugtenburg, J., Herzfeld, J., Mathies, R.A., & Griffin, R.G. (1985) Biochemistry 24, 6955-6962; Baselt, D.R., Fodor, S.P.A., van der Steen, R., Lugtenburg, J., Bogomolni, R.A., & Mathies, R.A. (1989) Biophys. J. 55, 193-196], we suggest that the cyclopentenyl analogue's alpha-diketo function may be favorably positioned within the binding pocket and sufficiently reactive toward nucleophilic attack to cross-link an arginine located in or near the ring end of the chromophore cavity: Arg134 according to the current model of bacteriorhodopsin's tertiary structure [Henderson, R., Baldwin, J.M., Ceska, T.A., Zemlin, F., Beckmann, E., & Downing, K.H. (1990) J. Mol. Biol. 213, 899-929] or Arg82 as postulated from an alternate model constructed primarily to accommodate the external point charge contribution to bacteriorhodopsin's opsin shift. PMID:2007133

  6. Quantitative polarized Raman spectroscopy in highly turbid bone tissue

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  7. Optical spectroscopy for quantitative sensing in human pancreatic tissues

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

  8. Quantitative fiber-optic Raman spectroscopy for tissue Raman measurements

    NASA Astrophysics Data System (ADS)

    Duraipandian, Shiyamala; Bergholt, Mads; Zheng, Wei; Huang, Zhiwei

    2014-03-01

    Molecular profiling of tissue using near-infrared (NIR) Raman spectroscopy has shown great promise for in vivo detection and prognostication of cancer. The Raman spectra measured from the tissue generally contain fundamental information about the absolute biomolecular concentrations in tissue and its changes associated with disease transformation. However, producing analogues tissue Raman spectra present a great technical challenge. In this preliminary study, we propose a method to ensure the reproducible tissue Raman measurements and validated with the in vivo Raman spectra (n=150) of inner lip acquired using different laser powers (i.e., 30 and 60 mW). A rapid Raman spectroscopy system coupled with a ball-lens fiber-optic Raman probe was utilized for tissue Raman measurements. The investigational results showed that the variations between the spectra measured with different laser powers are almost negligible, facilitating the quantitative analysis of tissue Raman measurements in vivo.

  9. Mapping of local oxide properties by quantitative scanning capacitance spectroscopy

    SciTech Connect

    Brezna, W.; Harasek, S.; Lugstein, A.; Leitner, T.; Hoffmann, H.; Bertagnolli, E.; Smoliner, J.

    2005-05-01

    In this work, quantitative scanning capacitance spectroscopy was applied to investigate the local dielectric properties of a chemical vapor deposition grown ZrO{sub 2} layer on low-doped silicon. Due to self-organization effects during the growth process, the ZrO{sub 2} layer shows small, periodic thickness variations on micrometer length scales near the sample edges. The measured capacitance data and derived oxide charge densities show the same periodicity as the thickness variations. The magnitude of the change of the oxide charge density, however, cannot be explained by the small thickness variations and is attributed to a local periodic change of the growth dynamics.

  10. Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

    DOE PAGESBeta

    Perras, Frédéric A.

    2016-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities. Two-dimensional

  11. Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

    SciTech Connect

    Perras, Frederic A.

    2015-12-15

    Here, nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  13. The UV/visible absorption spectra of shocked nitromethane - amine mixtures

    NASA Astrophysics Data System (ADS)

    Constantinou, C. P.; Gupta, Y. M.

    1994-07-01

    Time-resolved optical absorption spectroscopy has been used to examine the response of a mixture of nitromethane with ethylenediamine (0.1% by weight) to stepwise shock compression up to a pressure of 14 GPa. Unlike pure nitromethane, the mixture shows an irreversible time-dependent shift in the absorption edge of up to 100 nm towards longer wavelengths. This provides evidence for the chemical nature of the mechanism by which nitromethane is sensitized in the presence of amines.

  14. Quantitative analysis of vitamin A using Fourier transform Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Hancewicz, Thomas M.; Petty, Chris

    1995-11-01

    Near infrared Fourier transform Raman spectroscopy has been successfully used to quantitatively analyze vitamin A additives in a sorbitan mono-oleate base vehicle. Although measurements can be made on the raw materials, their high viscosity causes them to be difficult to handle in an industrial testing lab. Accurate quantitation is possible using a simple dilution of the sample. This reduces the overall measurement time by speeding up preparation and clean-up. Results are quantified over a range of 0.05 ml -1 up to 1 mg ml -1 using a partial least-squares analysis model. A discussion is made of factors affecting quantitative analysis using FT Raman instrumentation in an industrial environment. Application of the multiplicative scatter correction (MSC) as a pretreatment step for Raman data is discussed with reference to the partial least squares (PLS) calibration. A discussion is presented to the information imbedded in the latent PLS factors and how analysis of these factors can often add to an understanding of the chemical information being modeled.

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

    PubMed

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

    2005-09-01

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

  16. Quantitative Cherenkov emission spectroscopy for tissue oxygenation assessment

    PubMed Central

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

    2012-01-01

    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

  17. HPLC separation post-column reaction, UV-visible and fluorescence detection of trace UO/sub 2//sup 2 +//U/sup 4 +/ species in aqueous solutions

    SciTech Connect

    Karimi, A.R.

    1986-01-01

    In this study a method for the measurement of uranium in natural waters at sub-ppB concentration levels by the separation and determination of U/sup 4 +/ and UO/sub 2//sup 2 +/ species is proposed. Reversed phase high performance liquid chromatography, followed by a post-column reaction and a sensitive UV-visible detection system was the method of choice to determine qualitatively and quantitatively the two uranium species. Also a cation-exchange and fluorescence detection system was studied for separation and determination of UO/sub 2//sup 2 +/ ions. Uranyl ion was selectively complexed with L-phenylalanine moetie in the sample solution containing U/sup 4 +/ ions. Uranium (IV)/U(VI)-ligand was separated on a C/sub 18/ column with acetate buffer. Hexanesulfonate was found to be the choice for ion-pair reagent. The separation was best done with the acetate buffer at .01 M concentration and pH of 3.5. Absorption of the two species were measured after a post-column reaction with Arsenazo-III. Chromatographic parameters were calculated and a calibration curves were constructed. The detection limit for the procedure was 0.7 ..mu..g/mo and 1.2..mu..g/ml for U(IV) and U(VI) respectively. When U(VI) was separated on the cation-exchange column the limit of detection was calculated to be 1 ..mu..g/ml. The direct fluorometric method for U(VI) measurement results in a detection limit of 2 ppB and upper concentration limit of 2 ppM. The effect of interfering ions in the direct method of determination could be eliminated by dilution of sample solution.

  18. The UV-visible absorption and fluorescence spectroscopy indicators for monitoring the evolution of green waste composts.

    NASA Astrophysics Data System (ADS)

    Mounier, Stéphane; Abaker, Madi; Domeizel, Mariane; Rapetti, Nicola

    2014-05-01

    The maturity process of compost goes through several phases that have to be monitored in order to optimize the production process which in turn assure a good quality product and less time consumption. In order to estimate rapidly the phase where the compost is present and to measure the cellulose, the ratio C:N and the Stability Index Organic Matter (ISMO) a crucial parameter that needs to be monitored and controlled is the temperature. However, the temperature is not really a good indicator for the maturity of the compost because it is not constant and it depends on the mixing and environmental processes. The final measurements are performed at the end of the production process after certain time period that is subjectively determined by the producer. The work presented here is based on the optical properties of the organic matter that are observed each month for a period of six months. The organic matter of 5 composts was extracted by water and analyzed by UV-VIS spectroscopic technique [1] and 3D fluorescence emission technique [2]. The usual indexes were calculated (E2/E3, E4/E6, EBZ/EET, SUVA254), but also the PARAFAC decomposition of the 3D fluorescence response by Milori [3] and the Hx indexes [4]. The comparison of these results and the cellulose composition with the corresponding ISMO index indicates that the maturity process occurs more rapidly then the expectation of the producers. Further, the combination of the indicators gives useful information about different processes that take place during the maturity of the compost such as aromatization, the condensation and the stabilization of the parameters.

  19. UV-visible spectroscopy of macrocyclic alkyl, nitrosyl and halide complexes of cobalt and rhodium. Experiment and calculation

    SciTech Connect

    Hull, Emily A.; West, Aaron C.; Pestovsky, Oleg; Kristian, Kathleen E.; Ellern, Arkady; Dunne, James F.; Carraher, Jack M.; Bakac, Andreja; Windus, Theresa L.

    2015-01-22

    In this paper, transition metal complexes (NH3)5CoX2+ (X = CH3, Cl) and L(H2O)MX2+, where M = Rh or Co, X = CH3, NO, or Cl, and L is a macrocyclic N4 ligand are examined by both experiment and computation to better understand their electronic spectra and associated photochemistry. Specifically, irradiation into weak visible bands of nitrosyl and alkyl complexes (NH3)5CoCH32+ and L(H2O)MIIIX2+ (X = CH3 or NO) leads to photohomolysis that generates the divalent metal complex and ˙CH3 or ˙NO, respectively. On the other hand, when X = halide or NO2, visible light photolysis leads to dissociation of X and/or cis/trans isomerization. Computations show that visible bands for alkyl and nitrosyl complexes involve transitions from M–X bonding orbitals and/or metal d orbitals to M–X antibonding orbitals. In contrast, complexes with X = Cl or NO2 exhibit only d–d bands in the visible, so that homolytic cleavage of the M–X bond requires UV photolysis. UV-Vis spectra are not significantly dependent on the structure of the equatorial ligands, as shown by similar spectral features for (NH3)5CoCH32+ and L1(H2O)CoCH32+.

  20. UV-visible spectroscopy of macrocyclic alkyl, nitrosyl and halide complexes of cobalt and rhodium. Experiment and calculation

    DOE PAGESBeta

    Hull, Emily A.; West, Aaron C.; Pestovsky, Oleg; Kristian, Kathleen E.; Ellern, Arkady; Dunne, James F.; Carraher, Jack M.; Bakac, Andreja; Windus, Theresa L.

    2015-01-22

    In this paper, transition metal complexes (NH3)5CoX2+ (X = CH3, Cl) and L(H2O)MX2+, where M = Rh or Co, X = CH3, NO, or Cl, and L is a macrocyclic N4 ligand are examined by both experiment and computation to better understand their electronic spectra and associated photochemistry. Specifically, irradiation into weak visible bands of nitrosyl and alkyl complexes (NH3)5CoCH32+ and L(H2O)MIIIX2+ (X = CH3 or NO) leads to photohomolysis that generates the divalent metal complex and ˙CH3 or ˙NO, respectively. On the other hand, when X = halide or NO2, visible light photolysis leads to dissociation of X– and/ormore » cis/trans isomerization. Computations show that visible bands for alkyl and nitrosyl complexes involve transitions from M–X bonding orbitals and/or metal d orbitals to M–X antibonding orbitals. In contrast, complexes with X = Cl or NO2 exhibit only d–d bands in the visible, so that homolytic cleavage of the M–X bond requires UV photolysis. UV-Vis spectra are not significantly dependent on the structure of the equatorial ligands, as shown by similar spectral features for (NH3)5CoCH32+ and L1(H2O)CoCH32+.« less

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Purcell, Dale Kevin

    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.

  3. A UV-Visible-NIR fluorescence lifetime imaging microscope for laser-based biological sensing with picosecond resolution

    NASA Astrophysics Data System (ADS)

    Urayama, P.; Zhong, W.; Beamish, J. A.; Minn, F. K.; Sloboda, R. D.; Dragnev, K. H.; Dmitrovsky, E.; Mycek, M.-A.

    This article describes the design and characterization of a wide-field, time-domain fluorescence lifetime imaging microscopy (FLIM) system developed for picosecond time-resolved biological imaging. The system consists of a nitrogen-pumped dye laser for UV-visible-NIR excitation (337.1-960 nm), an epi-illuminated microscope with UV compatible optics, and a time-gated intensified CCD camera with an adjustable gate width (200 ps-10-3 s) for temporally resolved, single-photon detection of fluorescence decays with 9.6-bit intensity resolution and 1.4-μm spatial resolution. Intensity measurements used for fluorescence decay calculations are reproducible to within 2%, achieved by synchronizing the ICCD gate delay to the excitation laser pulse via a constant fraction optical discriminator and picosecond delay card. A self-consistent FLIM system response model is presented, allowing for fluorescence lifetimes (0.6 ns) significantly smaller than the FLIM system response (1.14 ns) to be determined to 3% of independently determined values. The FLIM system was able to discriminate fluorescence lifetime differences of at least 50 ps. The spectral tunability and large temporal dynamic range of the system are demonstrated by imaging in living human cells: UV-excited endogenous fluorescence from metabolic cofactors (lifetime 1.4 ns) and 460-nm excited fluorescence from an exogenous oxygen-quenched ruthenium dye (lifetime 400 ns).

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

    NASA Astrophysics Data System (ADS)

    Sangami, G.; Dharmaraj, N.

    2012-11-01

    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.

  5. Quasi-simultaneous observations of BL Lac object Mrk 501 in X-ray, UV, visible, IR, and radio frequencies

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    Observations in the X-ray, UV, visible, IR and radio regions of the BL Lac object Mrk 501 made over the course of two months are reported. The measurements were made with the A2 experiment on HEAO 1 (X-ray), the SWP and LWR cameras on IUE (UV), the 5-m Hale telescope (visible), the 2.5-m telescope at Mount Wilson (IR), the NRAO 92-m radio telescope at Green Bank (4750 MHz) and the 46-m radio telescope at the Algonquin Observatory (10275 and 10650 MHz). The quasi-simultaneously observed spectral slope is found to be positive and continuous from the X-ray to the UV, but to gradually flatten and possibly turn down from the mid-UV to the visible; the optical-radio emission cannot be accounted for by a single power law. The total spectrum is shown to be compatible with a synchrotron self-Compton emission mechanism, while the spectrum from the visible to the X-ray is consistent with synchrotron radiation or inverse-Compton scattering by a hot thermal electron cloud. The continuity of the spectrum from the UV to the X-ray is noted to imply a total luminosity greater than previous estimates by a factor of 3-4.

  6. NO2 Profile Retrieval using airborne multi axis UV-visible skylight absorption measurements over central Europe

    NASA Astrophysics Data System (ADS)

    Bruns, M.; Buehler, S. A.; Burrows, J. P.; Richter, A.; Rozanov, A.; Wang, P.; Heue, K.-P.; Platt, U.; Pundt, I.; Wagner, T.

    2006-01-01

    A recent development in ground-based remote sensing of atmospheric constituents by UV/visible absorption measurements of scattered light is the simultaneous use of several directions with small elevation angles in addition to the traditional zenith-sky pointing. The different light paths through the atmosphere enable the vertical distribution of some atmospheric absorbers such as NO2, BrO or O3 to be retrieved. In this study, the amount of profile information that can be retrieved from such measurements on aircraft is investigated for the trace gas NO2. A Sensitivity study on synthetic data is performed for a combination of four lines of sight (LOS) (0° (nadir), 88°, 92°, and 180° (zenith)) and three wavelength regions [center wavelengths: 362.5 nm, 437.5 nm, and 485.0 nm]. This investigation demonstrates the potential of this LOS/wavelengths setup to retrieve a significant amount of profile information from airborne multiaxis differential optical absorption spectrometer (AMAXDOAS) measurements with a vertical resolution of 3.0 to 4.5 km in the lower troposphere and 2.0 to 3.5 km near flight altitude. Above 13 km the profile information content of AMAXDOAS measurements is sparse. Further, retrieved profiles with a significant amount (up to 3.2 ppbv) of NO2 in the boundary layer over the Po-valley (Italy) are presented. Airborne multiaxis measurements are thus a promising tool for atmospheric studies in the troposphere.

  7. Vibrational, NMR and UV-visible spectroscopic investigation and NLO studies on benzaldehyde thiosemicarbazone using computational calculations

    NASA Astrophysics Data System (ADS)

    Moorthy, N.; Prabakar, P. C. Jobe; Ramalingam, S.; Pandian, G. V.; Anbusrinivasan, P.

    2016-04-01

    In order to investigate the vibrational, electronic and NLO characteristics of the compound; benzaldehyde thiosemicarbazone (BTSC), the XRD, FT-IR, FT-Raman, NMR and UV-visible spectra were recorded and were analysed with the calculated spectra by using HF and B3LYP methods with 6-311++G(d,p) basis set. The XRD results revealed that the stabilized molecular systems were confined in orthorhombic unit cell system. The cause for the change of chemical and physical properties behind the compound has been discussed makes use of Mulliken charge levels and NBO in detail. The shift of molecular vibrational pattern by the fusing of ligand; thiosemicarbazone group with benzaldehyde has been keenly observed. The occurrence of in phase and out of phase molecular interaction over the frontier molecular orbitals was determined to evaluate the degeneracy of the electronic energy levels. The thermodynamical studies of the temperature region 100-1000 K to detect the thermal stabilization of the crystal phase of the compound were investigated. The NLO properties were evaluated by the determination of the polarizability and hyperpolarizability of the compound in crystal phase. The physical stabilization of the geometry of the compound has been explained by geometry deformation analysis.

  8. UV-visible scanning spectrophotometry and chemometric analysis as tools for carotenoids analysis in cassava genotypes (Manihot esculenta Crantz).

    PubMed

    Moresco, Rodolfo; Uarrota, Virgílio Gavicho; Pereira, Aline; Tomazzoli, Maíra Maciel; Nunes, Eduardo da C; Peruch, Luiz Augusto Martins; Gazzola, Jussara; Costa, Christopher; Rocha, Miguel; Maraschin, Marcelo

    2015-01-01

    In this study, the metabolomics characterization focusing on the carotenoid composition of ten cassava (Manihot esculenta) genotypes cultivated in southern Brazil by UV-visible scanning spectrophotometry and reverse phase-high performance liquid chromatography was performed. Cassava roots rich in β-carotene are an important staple food for populations with risk of vitamin A deficiency. Cassava genotypes with high pro-vitamin A activity have been identified as a strategy to reduce the prevalence of deficiency of this vitamin. The data set was used for the construction of a descriptive model by chemometric analysis. The genotypes of yellow-fleshed roots were clustered by the higher concentrations of cis-β-carotene and lutein. Inversely, cream-fleshed roots genotypes were grouped precisely due to their lower concentrations of these pigments, as samples rich in lycopene (red-fleshed) differed among the studied genotypes. The analytical approach (UV-Vis, HPLC, and chemometrics) used showed to be efficient for understanding the chemodiversity of cassava genotypes, allowing to classify them according to important features for human health and nutrition. PMID:26673931

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

    SciTech Connect

    Yu Huagen; Nyman, Gunnar E-mail: nyman@chem.gu.se

    2012-05-20

    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.

  10. Infrared and UV-visible spectroscopic studies of gamma-irradiated Sb2O3-B2O3 glasses

    NASA Astrophysics Data System (ADS)

    Marzouk, Samir Y.; Elbatal, Fatma H.

    2014-04-01

    Glasses from the binary Sb2O3-B2O3 system were prepared in the compositional range 90-30 Sb2O3 mol%. UV-visible spectroscopic measurements were carried out in the range 190-1100 nm before and after successive gamma rays irradiation (1, 3, 4 Mrad). Infrared absorption of the samples was measured by the KBr technique in the range 4000-400 cm-1 and the same measurements were repeated after gamma irradiation with 4 kGy. Experimental results indicate that antimony borate glasses reveal quite shielding behavior towards gamma rays irradiation as observed with heavy metal cations bearing glasses such as Bi3+ and Pb2+. Infrared absorption spectra reveal characteristic absorption bands specific for the glass-forming borate units and Sb-O units. Glasses containing high antimony oxide content can thus be recommended as promising radiation-shielding material because they show resistant to gamma irradiation due to the presence of high percent of heavy metal oxide (Sb2O3).

  11. Quantitation of secondary structure in ATR infrared spectroscopy

    PubMed Central

    Marsh, D

    1999-01-01

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

  12. Silver nanoparticles coated with natural polysaccharides as models to study AgNP aggregation kinetics using UV-Visible spectrophotometry upon discharge in complex environments.

    PubMed

    Lodeiro, Pablo; Achterberg, Eric P; Pampín, Joaquín; Affatati, Alice; El-Shahawi, Mohammed S

    2016-01-01

    This study provides quantitative information on the aggregation and dissolution behaviour of silver nanoparticles (AgNPs) upon discharge in fresh and sea waters, represented here as NaCl solutions of increasing ionic strength (up to 1M) and natural fjord waters. Natural polysaccharides, sodium alginate (ALG) and gum Arabic (GA), were used as coatings to stabilize the AgNPs and the compounds acted as models to study AgNP aggregation kinetics. The DLVO theory was used to quantitatively describe the interactions between the AgNPs. The stability of AgNPs was established using UV-Visible spectrophotometry, including unique information collected during the first seconds of the aggregaton process. Alginate coating resulted in a moderate stabilization of AgNPs in terms of critical coagulation concentration (~82mM NaCl) and a low dissolution of <10% total Ag in NaCl solutions up to 1M. Gum Arabic coated AgNPs were more strongly stabilized, with ~7-30% size increase up to 77mM NaCl, but only when the silver ion content initially present in solution was low (<10% total Ag). The ALG and GA coated AgNPs showed a strongly enhanced stability in natural fjord waters (ca. 5h required to reduce the area of the surface plasmon resonance band (SPRB) by two fold) compared with NaCl at an equivalent ionic strength (1-2min period for a two fold SPRB reduction). This is ascribed to a stabilizing effect from dissolved organic matter present in natural fjord waters. Interestingly, for AgNP-GA solutions with 40% of total silver present as unreacted silver ions in the NP stock solution, fast aggregation kinetics were observed in NaCl solutions (SPRB area was reduced by ca. 50% within 40-150min), with even more rapid removal in fjord waters, attributed to the high amount of silver-chloride charged species, that interact with the NP coating and/or organic matter and reduce the NPs stabilization. PMID:26363390

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

    PubMed

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

    2014-01-01

    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 (10(2)) and a UV/visible rejection ratio of 300. It also exhibits fast response times of τ(rise) ~ 200 μs and τ(fall) ~ 950 μs. 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 μW cm(-2)) ambient white light with a high photocurrent density of 120 nA cm(-2) making it an efficient ambient white light detector. PMID:24232600

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

    NASA Astrophysics Data System (ADS)

    Sivakumar, V.; Wyk, H. V.

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

  15. NO2 Profile retrieval using airborne multi axis UV-visible skylight absorption measurements over central Europe

    NASA Astrophysics Data System (ADS)

    Bruns, M.; Buehler, S. A.; Burrows, J. P.; Richter, A.; Rozanov, A.; Wang, P.; Heue, K. P.; Platt, U.; Pundt, I.; Wagner, T.

    2006-07-01

    A recent development in ground-based remote sensing of atmospheric constituents by UV/visible absorption measurements of scattered light is the simultaneous use of several directions with small elevation angles in addition to the traditional zenith-sky pointing. The different light paths through the atmosphere enable the vertical distribution of some atmospheric absorbers such as NO2, BrO or O3 to be retrieved. In this study, the amount of profile information that can be retrieved from such measurements on aircraft is investigated for the trace gas NO2. A Sensitivity study on synthetic data is performed for a combination of four lines of sight (LOS) (0°(nadir), 88°, 92°, and 180° (zenith)) and three wavelength regions [center wavelengths: 362.5 nm, 437.5 nm, and 485.0 nm]. The method used in this work is a combination of two previously established methods described in Petritoli et al. (2002) and Wang et al. (2004). The investigation presented here demonstrates the potential of this LOS/wavelengths setup to retrieve a significant amount of profile information from airborne multiax is differential optical absorption spectrometer (AMAXDOAS) measurements with a vertical resolution of 3.0 to 4.5 km in the lower troposphere and 2.0 to 3.5 km near flight altitude. Above 13 km the profile information content of AMAXDOAS measurements is sparse. The retrieval algorithm used in this work is the AMAXDOAS profile retrievalalgorithm (APROVAL). Further, retrieved profiles with a significant amount (up to 3.2 ppbv) of NO2 in the boundary layer over the Po-valley (Italy) are presented. Airborne multiaxis measurements are thus a promising tool for atmospheric studies in the troposphere.

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

    PubMed

    Ogata, Yuko; Scampavia, Louis; Růzicka, Jaromír; Scott, C Ronald; Gelb, Michael H; Turecek, Frantisek

    2002-09-15

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

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

    ERIC Educational Resources Information Center

    Hill, Devon W.; And Others

    1988-01-01

    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)

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 τrise ~ 200 μs and τfall ~ 950 μs. 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 μW 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 τrise ~ 200 μs and τfall ~ 950 μs. 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 μW 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

  19. Quantitative Determination of DNA-Ligand Binding Using Fluorescence Spectroscopy

    ERIC Educational Resources Information Center

    Healy, Eamonn F.

    2007-01-01

    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.

  20. Quantitative Measurement of Trans-Fats by Infrared Spectroscopy

    ERIC Educational Resources Information Center

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

    2007-01-01

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

  1. Controllable self-assembly of a novel Bi2MoO6-based hybrid photocatalyst: excellent photocatalytic activity under UV, visible and near-infrared irradiation.

    PubMed

    Hao, Yuchen; Dong, Xiaoli; Zhai, Shangru; Wang, Xiuying; Ma, Hongchao; Zhang, Xiufang

    2016-05-01

    Herein, using a simple one-step method, a Bi2MoO6-based photocatalyst with novel ultrathin nanohollow structure and simultaneous sub-10 nm Bi nanoparticles and sub-1 nm graphitic nitrogen-doped carbon nanodot (NCD) modification were successfully obtained. The coordination impact of the novel structure, SPR effect of Bi nanoparticles, up-conversion performance of graphitic NCDs and cooperative electronic capture properties of Bi metal and NCDs make the hybrid simultaneously exhibit fast charge separation and broad spectrum photocatalytic activity under UV, visible and near-infrared irradiation, leading to excellent photooxidation and photoreduction performance. PMID:27026588

  2. Quantitatively Resolving Multivalent Interactions on Macroscopic Scale Using Force Spectroscopy

    PubMed Central

    Hu, Qiongzheng; Yang, Haopeng; Wang, Yuhong; Xu, Shoujun

    2016-01-01

    Multivalent interactions remain difficult to be characterized and consequently controlled, particularly on a macroscopic scale. Using force-induced remnant magnetization spectroscopy (FIRMS), we have resolved the single-, double-, and triple- biotin—streptavidin interactions, multivalent DNA interactions and CXCL12-CXCR4 interactions, on millimetre-scale surfaces. Our results establish FIRMS as a viable method for systematic resolution and controlled formation of multivalent interactions. PMID:26864087

  3. Direct and quantitative photothermal absorption spectroscopy of individual particulates

    SciTech Connect

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

    2013-12-23

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

  4. Quantitative Remote Laser-Induced Breakdown Spectroscopy by Multivariate Analysis

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    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.

  5. Machine learning methods for quantitative analysis of Raman spectroscopy data

    NASA Astrophysics Data System (ADS)

    Madden, Michael G.; Ryder, Alan G.

    2003-03-01

    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.

  6. Quantitative monitoring of yeast fermentation using Raman spectroscopy.

    PubMed

    Iversen, Jens A; Berg, Rolf W; Ahring, Birgitte K

    2014-08-01

    Compared to traditional IR methods, Raman spectroscopy has the advantage of only minimal interference from water when measuring aqueous samples, which makes this method potentially useful for in situ monitoring of important industrial bioprocesses. This study demonstrates real-time monitoring of a Saccharomyces cerevisiae fermentation process using a Raman spectroscopy instrument equipped with a robust sapphire ball probe. A method was developed to correct the Raman signal for the attenuation caused by light scattering cell particulate, hence enabling quantification of reaction components and possibly measurement of yeast cell concentrations. Extinction of Raman intensities to more than 50 % during fermentation was normalized with approximated extinction expressions using Raman signal of water around 1,627 cm(-1) as internal standard to correct for the effect of scattering. Complicated standard multi-variant chemometric techniques, such as PLS, were avoided in the quantification model, as an attempt to keep the monitoring method as simple as possible and still get satisfactory estimations. Instead, estimations were made with a two-step approach, where initial scattering correction of attenuated signals was followed by linear regression. In situ quantification measurements of the fermentation resulted in root mean square errors of prediction (RMSEP) of 2.357, 1.611, and 0.633 g/L for glucose, ethanol, and yeast concentrations, respectively. PMID:24996999

  7. Structural elucidation and estimation of the acute toxicity of the major UV-visible photoproduct of fludioxonil - detection in both skin and flesh samples of grape.

    PubMed

    Lassalle, Yannick; Nicol, Édith; Genty, Christophe; Bourcier, Sophie; Bouchonnet, Stéphane

    2015-06-01

    Ultraviolet (UV)-visible irradiation of fludioxonil was investigated with two photoreactors using either a mercury or xenon vapor lamp. In both cases, it led to the formation of only one photoproduct in significant amount: 2-(2,2-difluorobenzo[d][1,3]dioxol-4-yl)-2-(nitrosomethylene)-4-oxobutanenitrile, which has been characterized using Liquid Chromatography - High Resolution - Tandem Mass Spectrometry (LC-HR-MS/MS) coupling. A photolysis pathway has been proposed to rationalize its formation in degassed water. In vitro bioassays on Vibrio fischeri bacteria showed that UV-vis irradiation of an aqueous solution of fludioxonil significantly increases its toxicity. Because no other by-product was detected in significant amount, the photoproduct mentioned above may be considered mainly responsible for this increase in toxicity. Grape berries treated with a 50 ppm aqueous solution of fludioxonil were submitted to UV-visible irradiation under laboratory conditions. The fungicide and photoproduct were detected in both skin and flesh of berries, even after they have been rinsed with water. The ability of the photoproduct to pass through the fruit skin is comparable with that of fludioxonil. These results are of concern for consumers because they mean that water tap rinsing does not lead to efficient removing of both compounds. PMID:26169141

  8. Quantitative Raman spectroscopy for the analysis of carrot bioactives.

    PubMed

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

    2013-03-20

    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 μg g(-1) dry weight (DW). Polyacetylene concentrations were 74-4846 μg g(-1) DW, highest in wild carrots. The polyacetylenes were falcarinol, 6-1237 μg g(-1) DW; falcarindiol, 42-3475 μg g(-1) DW; and falcarindiol 3-acetate, 27-649 μg 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 μg g(-1)) concentrations based on Raman spectral intensity in the region of 2250 cm(-1) was produced. PMID:23441972

  9. A novel method for generating quantitative local electrochemical impedance spectroscopy

    SciTech Connect

    Lillard, R.S. ); Moran, P.J. ); Isaacs, H.S. )

    1992-04-01

    This paper reports on a local electrochemical impedance spectroscopy (LEIS) technique for mapping the ac impedance distribution, as a function of frequency, of an electrode. In LEIS, as in traditional ac impedance methods, a sinusoidal voltage perturbation between the working and reference electrode is maintained by driving an ac current between the working electrode and a distant counterelectrode with a potentiostat. Local ac impedances are then derived from the ratio of the applied ac voltage and the local ac solution current density. The local ac current density is obtained from potential difference measurements near the electrode surface using a probe consisting of two micro-electrodes. By measuring the ac potential difference between the micro-electrodes, and knowing their separation distance and the solution conductivity, the local ac solution current density is derived. The accuracy of the local ac impedance data generated with this technique was established by investigating two model systems.

  10. Synthesis, spectral analysis (FT-IR, 1H NMR, 13C NMR and UV-visible) and quantum chemical studies on molecular geometry, NBO, NLO, chemical reactivity and thermodynamic properties of novel 2-amino-4-(4-(dimethylamino)phenyl)-5-oxo-6-phenyl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile

    NASA Astrophysics Data System (ADS)

    Fatma, Shaheen; Bishnoi, Abha; Verma, Anil Kumar

    2015-09-01

    In the present study novel 2-amino-4-(4-(dimethylamino)phenyl)-5-oxo-6-phenyl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carbonitrile was synthesized and characterized by FT-IR, 1H NMR, 13C NMR, UV-visible spectroscopy and mass spectral analysis. The chemical calculations were done by DFT level of theory using Becke3-Lee-Yang-Parr (B3LYP) and Coulomb Attenuating Method (CAM-B3LYP)/6-31G(d,p) basis set. 1H, 13C chemical shifts and vibrational wavenumbers were calculated and good correlation with the experimental data has been accomplished. UV-Visible spectrum of the molecule was recorded in the region 200-500 nm and the electronic properties and composition were obtained using Time Dependent Density Functional Theory (TDDFT) method. Hyperconjugative interactions were studied with the help of natural bond orbital analysis. Electric dipole moment, polarizability and first static hyperpolarizability values have been calculated. The results show that the title compound possesses nonlinear optical behavior with non-zero values. The thermodynamic properties of the compound were calculated at different temperatures. The local reactivity descriptors show that C(7) is most reactive site for nucleophilic attack.

  11. Quantitative Sum-Frequency Generation Vibrational Spectroscopy of Molecular Surfaces and Interfaces: Lineshape, Polarization and Orientation

    SciTech Connect

    Wang, Hongfei; Velarde, Luis; Gan, Wei; Fu, Li

    2015-04-01

    Sum-frequency generation vibrational spectroscopy (SFG) can provide detailed information and understanding of molecular vibrational spectroscopy, orientational and conformational structure, and interactions of molecular surfaces and interfaces, through quantitative measurement and analysis. In this review, we present the current status and discuss the main developments on the measurement of intrinsic SFG spectral lineshape, formulations for polarization measurement and orientation analysis of the SFG-VS spectra. The main focus is to present a coherent formulation and discuss the main concepts or issues that can help to make SFG-VS a quantitative analytical and research tool in revealing the chemistry and physics of complex molecular surface and interface.

  12. Quantitative Analysis of Panax ginseng by FT-NIR Spectroscopy

    PubMed Central

    Xu, Xin-fang; Nie, Li-xing; Pan, Li-li; Hao, Bian; Yuan, Shao-xiong; Lin, Rui-chao; Bu, Hai-bo; Wang, Dan; Dong, Ling; Li, Xiang-ri

    2014-01-01

    Near-infrared spectroscopy (NIRS), a rapid and efficient tool, was used to determine the total amount of nine ginsenosides in Panax ginseng. In the study, the regression models were established using multivariate regression methods with the results from conventional chemical analytical methods as reference values. The multivariate regression methods, partial least squares regression (PLSR) and principal component regression (PCR), were discussed and the PLSR was more suitable. Multiplicative scatter correction (MSC), second derivative, and Savitzky-Golay smoothing were utilized together for the spectral preprocessing. When evaluating the final model, factors such as correlation coefficient (R2) and the root mean square error of prediction (RMSEP) were considered. The final optimal results of PLSR model showed that root mean square error of prediction (RMSEP) and correlation coefficients (R2) in the calibration set were 0.159 and 0.963, respectively. The results demonstrated that the NIRS as a new method can be applied to the quality control of Ginseng Radix et Rhizoma. PMID:24883224

  13. Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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.

  14. Gas-Phase Database for Quantitative Infrared Spectroscopy

    SciTech Connect

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

    2004-12-10

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

  15. Optical waveguide lightmode spectroscopy (OWLS) to monitor cell proliferation quantitatively.

    PubMed

    Hug, T S; Prenosil, J E; Maier, P; Morbidelli, M

    2002-10-20

    The use of microscopic observations used for in situ monitoring of cell proliferation in the production of epidermal autografts is not satisfactory. In particular, the identification of the projected cell area from microscopic pictures by image analysis (IA) depends on intensity edges and level of contrasts and is thus limited to subconfluent cultures. Some of these problems can be solved by using optical waveguide lightmode spectroscopy (OWLS), which measures the effective refractive index of a thin layer above an Si(Ti)O(2) waveguide surface. In this study the use of OWLS to monitor cell adhesion, spreading, and growth was studied. The sensitivity of the method was investigated by using three different cell lines, two fibroblasts and one hepatoma cell line. Cell proliferation of two strains of fibroblasts and hepatoma cells was monitored up to 2 days with the OWLS. In parallel, cell density was determined at different time points microscopically using an additional window in the measuring chamber. The cell density of fully spread cells ( approximately 4 h after attachment) was found to be proportional to the OWLS signal. In long-term cultures the influence of the cell density from single cells to confluent cell cultures upon the OWLS signal was investigated. The exponentially growing number of hepatoma resulted in a linear increase of the sensor signal. Due to this and to the fact that the proliferating cells exhibit contact inhibition, it was concluded that the cell contact area must decrease exponentially. The results show the strength of OWLS for monitoring the adhesion and proliferation of anchorage-dependent cells in applications where an on-line indicator of the total biomass is needed. Additionally, OWLS provides metabolic information through detection of the cell mass in close contact with the waveguide. PMID:12209777

  16. [Quantitative analysis of alloy steel based on laser induced breakdown spectroscopy with partial least squares method].

    PubMed

    Cong, Zhi-Bo; Sun, Lan-Xiang; Xin, Yong; Li, Yang; Qi, Li-Feng; Yang, Zhi-Jia

    2014-02-01

    In the present paper both the partial least squares (PLS) method and the calibration curve (CC) method are used to quantitatively analyze the laser induced breakdown spectroscopy data obtained from the standard alloy steel samples. Both the major and trace elements were quantitatively analyzed. By comparing the results of two different calibration methods some useful results were obtained: for major elements, the PLS method is better than the CC method in quantitative analysis; more importantly, for the trace elements, the CC method can not give the quantitative results due to the extremely weak characteristic spectral lines, but the PLS method still has a good ability of quantitative analysis. And the regression coefficient of PLS method is compared with the original spectral data with background interference to explain the advantage of the PLS method in the LIBS quantitative analysis. Results proved that the PLS method used in laser induced breakdown spectroscopy is suitable for quantitative analysis of trace elements such as C in the metallurgical industry. PMID:24822436

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

    ERIC Educational Resources Information Center

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

    2008-01-01

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

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

    ERIC Educational Resources Information Center

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

    2008-01-01

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

  19. Quantitative spectroscopy of photospheric-phase type II supernovae

    NASA Astrophysics Data System (ADS)

    Dessart, L.; Hillier, D. J.

    2005-07-01

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

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

    PubMed Central

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

    2011-01-01

    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

  1. 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)

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

    2012-02-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    SciTech Connect

    Felzer, B.; Hauff, P.; Goetz, A.F.H.

    1994-02-01

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

  4. Qualitative and quantitative laser-induced breakdown spectroscopy of bronze objects

    NASA Astrophysics Data System (ADS)

    Tankova, V.; Blagoev, K.; Grozeva, M.; Malcheva, G.; Penkova, P.

    2016-03-01

    Laser-induced breakdown spectroscopy (LIBS) is an analytical technique for qualitative and quantitative elemental analysis of solids, liquids and gases. In this work, the method was applied for investigation of archaeological bronze objects. The analytical information obtained by LIBS was used for qualitative determination of the elements in the material used for manufacturing of the objects under study. Quantitative chemical analysis was also performed after generating calibration curves with standard samples of similar matrix composition. Quantitative estimation of the elemental concentration of the bulk of the samples was performed, together with investigation of the surface layer of the objects. The results of the quantitative analyses gave indications about the manufacturing process of the investigated objects.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  6. Application of image processing for terahertz time domain spectroscopy imaging quantitative detection

    NASA Astrophysics Data System (ADS)

    Li, Li-juan; Wang, Sheng; Ren, Jiao-jiao; Zhou, Ming-xing; Zhao, Duo

    2015-03-01

    According to nondestructive testing principle for the terahertz time domain spectroscopy Imaging, using digital image processing techniques, through Terahertz time-domain spectroscopy system collected images and two-dimensional datas and using a range of processing methods, including selecting regions of interest, contrast enhancement, edge detection, and defects being detected. In the paper, Matlab programming is been use to defect recognition of Terahertz, by figuring out the pixels to determine defects defect area and border length, roundness, diameter size. Through the experiment of the qualitative analysis and quantitative calculation of Matlab image processing, this method of detection of defects of geometric dimension of the sample to get a better result.

  7. The spectroscopy of Venus

    NASA Technical Reports Server (NTRS)

    Beer, R.

    1982-01-01

    Problems in the spectroscopy of the planet are discussed. Two major problems are focused on: the almost total domination of the spectrum by CO2 (including almost every conceivable isotropic combination) makes the search for other species difficult; and the knowledge that no wavelengths short of the the microwave penetrate through the Venus cloud decks, which means that UV, visible, and IR remote sensing can investigate only the middle and upper atmosphere. The problem of intense multiple scattering is also considered.

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

    NASA Astrophysics Data System (ADS)

    Jiang, Dejun; Zhao, Shusen; Shen, Jingling

    2008-03-01

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

  9. Enhanced UV-visible response of bismuth subcarbonate nanowires for degradation of xanthate and photocatalytic reaction mechanism.

    PubMed

    Cui, Kuixin; He, Yuehui; Jin, Shengming

    2016-04-01

    (BiO)2CO3 nanowires were prepared by simple hydrothermal treatment of commercial Bi2O3 powders and characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of (BiO)2CO3 nanowires was studied through degradation of sodium isopropyl xanthate. Photocatalytic experimental results indicated that the as-prepared (BiO)2CO3 nanowires show high photocatalytic efficiency. Photocatalytic activity increased after two cycles. Time-dependent UV-vis spectra demonstrated that the final degradation products included isopropyl alcohol and carbon disulfide. UV-vis diffuse reflection spectra showed that the band gap of the as-prepared (BiO)2CO3 nanowires and recycled (BiO)2CO3 nanowires were 2.75 eV and 1.15 eV, respectively. XPS results indicated that formation of Bi2S3@(BiO)2CO3 core-shell nanowires occurred after recycled photodegradation of isopropyl xanthate owing to existence of two types of Bi configurations in the recycled (BiO)2CO3 nanowires. A probable degradation mechanism of isopropyl xanthate was also proposed. PMID:26866962

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

    PubMed

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

    2015-02-01

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

  11. [Study of infrared spectroscopy quantitative analysis method for methane gas based on data mining].

    PubMed

    Zhang, Ai-Ju

    2013-10-01

    Monitoring of methane gas is one of the important factors affecting the coal mine safety. The online real-time monitoring of the methane gas is used for the mine safety protection. To improve the accuracy of model analysis, in the present paper, the author uses the technology of infrared spectroscopy to study the gas infrared quantitative analysis algorithm. By data mining technology application in multi-component infrared spectroscopy quantitative analysis algorithm, it was found that cluster analysis partial least squares algorithm is obviously superior to simply using partial least squares algorithm in terms of accuracy. In addition, to reduce the influence of the error on the accuracy of model individual calibration samples, the clustering analysis was used for the data preprocessing, and such denoising method was found to improve the analysis accuracy. PMID:24409709

  12. Quantitative Detection of Pharmaceuticals Using a Combination of Paper Microfluidics and Wavelength Modulated Raman Spectroscopy

    PubMed Central

    Craig, Derek; Mazilu, Michael; Dholakia, Kishan

    2015-01-01

    Raman spectroscopy has proven to be an indispensable technique for the identification of various types of analytes due to the fingerprint vibration spectrum obtained. Paper microfluidics has also emerged as a low cost, easy to fabricate and portable approach for point of care testing. However, due to inherent background fluorescence, combining Raman spectroscopy with paper microfluidics is to date an unmet challenge in the absence of using surface enhanced mechanisms. We describe the first use of wavelength modulated Raman spectroscopy (WMRS) for analysis on a paper microfluidics platform. This study demonstrates the ability to suppress the background fluorescence of the paper using WMRS and the subsequent implementation of this technique for pharmaceutical analysis. The results of this study demonstrate that it is possible to discriminate between both paracetamol and ibuprofen, whilst, also being able to detect the presence of each analyte quantitatively at nanomolar concentrations. PMID:25938464

  13. Quantitative Determination of Carthamin in Carthamus Red by 1H-NMR Spectroscopy.

    PubMed

    Yoshida, Takamitsu; Terasaka, Kazuyoshi; Kato, Setsuko; Bai, Fan; Sugimoto, Naoki; Akiyama, Hiroshi; Yamazaki, Takeshi; Mizukami, Hajime

    2013-01-01

    Carthamus Red is a food colorant prepared from the petals of Carthamus tinctorius (Asteraceae) whose major pigment is carthamin. Since an authentic carthamin standard is difficult to obtain commercially for the preparation of calibration curves in HPLC assays, we applied (1)H-NMR spectroscopy to the quantitative determination of carthamin in commercial preparations of Carthamus Red. Carthamus Red was repeatedly extracted in methanol and the extract was dissolved in pyridine-d(5) containing hexamethyldisilane (HMD) prior to (1)H-NMR spectroscopic analysis. The carthamin contents were calculated from the ratios of singlet signal intensities at approximately σ: 9.3 derived from H-16 of carthamin to those of the HMD signal at σ: 0. The integral ratios exhibited good repeatability among NMR spectroscopic analyses. Both the intra-day and inter-day assay variations had coefficients of variation of <5%. Based on the coefficient of absorption, the carthamin contents of commercial preparations determined by (1)H-NMR spectroscopy correlated well with those determined by colorimetry, although the latter were always approximately 1.3-fold higher than the former, irrespective of the Carthamus Red preparations. In conclusion, the quantitative (1)H-NMR spectroscopy used in the present study is simple and rapid, requiring no carthamin standard for calibration. After HMD concentration has been corrected using certified reference materials, the carthamin contents determined by (1)H-NMR spectroscopy are System of Units (SI)-traceable. PMID:24436958

  14. Real time high frequency monitoring of water quality in river streams using a UV-visible spectrometer: interest, limits and consequences for monitoring strategies

    NASA Astrophysics Data System (ADS)

    Faucheux, Mikaël; Fovet, Ophélie; Gruau, Gérard; Jaffrézic, Anne; Petitjean, Patrice; Gascuel-Odoux, Chantal; Ruiz, Laurent

    2013-04-01

    Stream water chemistry is highly variable in space and time, therefore high frequency water quality measurement methods are likely to lead to conceptual advances in the hydrological sciences. Sub-daily data on water quality improve the characterization of pollutant sources and pathways during flood events as well as during long-term periods [1]. However, real time, high frequency monitoring devices needs to be properly calibrated and validated in real streams. This study analyses data from in situ monitoring of a stream water quality. During two hydrological years (2010-11, 2011-12), a submersible UV-visible spectrometer (Scan Spectrolyser) was used for surface water quality measurement at the outlet of a headwater catchment located at Kervidy-Naizin, Western France (AgrHys long-term hydrological observatory, http://www.inra.fr/ore_agrhys/). The spectrometer is reagentless and equipped with an auto-cleaning system. It allows real time, in situ and high frequency (20 min) measurements and uses a multiwavelengt spectral (200-750 nm) for simultaneous measurement of nitrate, dissolved organic carbon (DOC) and total suspended solids (TSS). A global calibration based on a PLS (Partial Least Squares) regression is provided by the manufacturer as default configuration of the UV-visible spectrometer. We carried out a local calibration of the spectrometer based on nitrates and DOC concentrations analysed in the laboratory from daily manual sampling and sub-daily automatic sampling of flood events. TSS results are compared with 15 min turbidity records from a continuous turdidimeter (Ponsel). The results show a good correlation between laboratory data and spectrometer data both during basis flows periods and flood events. However, the local calibration gives better results than the global one. Nutrient fluxes estimates based on high and different low frequency time series (daily to monthly) are compared to discuss the implication for environmental monitoring strategies. Such monitoring methods can therefore be interesting for designing monitoring strategy of environmental observatory and provide dense time series likely to highlight patterns or trends using appropriate approaches such as spectral analysis [2]. 1. Wade, A.J. et al., HESS Discuss., 2012. 9(5), p.6458- 6506. 2. Aubert, A. et al., submitted to EGU 2013-4745 vol. 15.

  15. Applications of quantitative 1H- and 13C-NMR spectroscopy in drug analysis.

    PubMed

    Pieters, L A; Vlietinck, A J

    1989-01-01

    The usefulness of 1H and 13C Fourier transform (FT) nuclear magnetic resonance spectroscopy (1H- and 13C-NMR) as quantitative methods stems from the potential direct relationship between the area under an NMR peak and the number of the particular type of nuclei that give rise to the signal, though it is necessary, especially for quantitative 13C-NMR, to take some precautions. The experimental limitations that have to be overcome in order to obtain quantitative 13C-NMR spectra are associated with the relaxation time, the nuclear Overhauser effect (NOE), and the NMR instrument itself (filter characteristics, power level of the exciting pulse, dynamic range, digital resolution). Practical problems aside, 13C-NMR has a greater potential than 1H-NMR for the study of organic systems. The sensitivity of 13C chemical shifts to small differences in molecular environment, coupled with a large chemical shift range, gives a "chromatographic" separation of resonances of interest, and has made 13C-NMR an attractive method for analysing complex mixtures. Some applications of quantitative 1H- and 13C-NMR spectroscopy in drug analysis are discussed. PMID:2490526

  16. Quantitative determination and validation of avermectin B1a in commercial products using quantitative nuclear magnetic resonance spectroscopy.

    PubMed

    Hou, Zhuoni; Liang, Xianrui; Du, Liping; Su, Feng; Su, Weike

    2014-09-01

    Nuclear magnetic resonance is defined as a quantitative spectroscopic tool that enables a precise determination of the number of substances in liquids as well as in solids. There is few report demonstrating the application of NMR in the quantification of avermectin B1a (AVB1a ); here, a proton nuclear magnetic resonance spectroscopy ((1) H NMR) using benzene [1-methoxy-4-(2-nitroethyl) (PMN)] as an internal standard and deuterochloroform as an NMR solvent was tested for the quantitative determination of AVB1a . The integrated signal of AVB1a at 5.56?ppm and the signal of PMN at 8.14?ppm in the (1) H NMR spectrum were used for quantification purposes. Parameters of specificity, linearity, accuracy, precision, intermediate precision, range, limit of detection (LOD), limit of quantification (LOQ), stability and robustness were validated. The established method was accurate and precise with good recovery (98.86%) and relative standard deviation (RSD) of assay (0.34%) within the linearity of the calibration curve ranging from 5.08 to 13.58?mg/ml (R(2) ?=?0.9999). The LOD and LOQ were 0.009 and 0.029?mg/ml, which indicated the excellent sensitivity of the method. The stability of the method was testified by a calculated RSD of 0.11%. The robustness was testified by modification of four different parameters, and the differences among each parameter were all less than 0.1%. Comparing with the assay described by the manufacturer of avermectin tablets, there was no significant difference between the assay obtained by HPLC and quantitative NMR (qNMR), which indicated qNMR was a simple and efficient method for the determination of AVB1a in commercial formulation products. PMID:24943110

  17. Evaluation of Hydrodynamic Chromatography Coupled with UV-Visible, Fluorescence and Inductively Coupled Plasma Mass Spectrometry Detectors for Sizing and Quantifying Colloids in Environmental Media

    PubMed Central

    Philippe, Allan; Schaumann, Gabriele E.

    2014-01-01

    In this study, we evaluated hydrodynamic chromatography (HDC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of nanoparticles in environmental samples. Using two commercially available columns (Polymer Labs-PDSA type 1 and 2), a set of well characterised calibrants and a new external time marking method, we showed that flow rate and eluent composition have few influence on the size resolution and, therefore, can be adapted to the sample particularity. Monitoring the agglomeration of polystyrene nanoparticles over time succeeded without observable disagglomeration suggesting that even weak agglomerates can be measured using HDC. Simultaneous determination of gold colloid concentration and size using ICP-MS detection was validated for elemental concentrations in the ppb range. HDC-ICP-MS was successfully applied to samples containing a high organic and ionic background. Indeed, online combination of UV-visible, fluorescence and ICP-MS detectors allowed distinguishing between organic molecules and inorganic colloids during the analysis of Ag nanoparticles in synthetic surface waters and TiO2 and ZnO nanoparticles in commercial sunscreens. Taken together, our results demonstrate that HDC-ICP-MS is a flexible, sensitive and reliable method to measure the size and the concentration of inorganic colloids in complex media and suggest that there may be a promising future for the application of HDC in environmental science. Nonetheless the rigorous measurements of agglomerates and of matrices containing natural colloids still need to be studied in detail. PMID:24587393

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  19. Evolution of the dust and water ice plume components as observed by the LCROSS visible camera and UV-visible spectrometer

    NASA Astrophysics Data System (ADS)

    Heldmann, Jennifer L.; Lamb, Justin; Asturias, Daniel; Colaprete, Anthony; Goldstein, David B.; Trafton, Laurence M.; Varghese, Philip L.

    2015-07-01

    The LCROSS (Lunar Crater Observation and Sensing Satellite) impacted the Cabeus crater near the lunar South Pole on 9 October 2009 and created an impact plume that was observed by the LCROSS Shepherding Spacecraft. Here we analyze data from the ultraviolet-visible spectrometer and visible context camera aboard the spacecraft. We use these data to constrain a numerical model to understand the physical evolution of the resultant plume. The UV-visible light curve peaks in brightness 18 s after impact and then decreases in radiance but never returns to the pre-impact radiance value for the ∼4 min of observation by the Shepherding Spacecraft. The blue:red spectral ratio increases in the first 10 s, decreases over the following 50 s, remains constant for approximately 150 s, and then begins to increase again ∼180 s after impact. Constraining the modeling results with spacecraft observations, we conclude that lofted dust grains remained suspended above the lunar surface for the entire 250 s of observation after impact. The impact plume was composed of both a high angle spike and low angle plume component. Numerical modeling is used to evaluate the relative effects of various plume parameters to further constrain the plume properties when compared with the observational data. Dust particle sizes lofted above the lunar surface were micron to sub-micron in size. Water ice particles were also contained within the ejecta cloud and simultaneously photo-dissociated and sublimated after reaching sunlight.

  20. Preparation and characterizations of SnO2 nanopowder and spectroscopic (FT-IR, FT-Raman, UV-Visible and NMR) analysis using HF and DFT calculations.

    PubMed

    Ayeshamariam, A; Ramalingam, S; Bououdina, M; Jayachandran, M

    2014-01-24

    In this work, pure and singe phase SnO2 Nano powder is successfully prepared by simple sol-gel combustion route. The photo luminescence and XRD measurements are made and compared the geometrical parameters with calculated values. The FT-IR and FT-Raman spectra are recorded and the fundamental frequencies are assigned. The optimized parameters and the frequencies are calculated using HF and DFT (LSDA, B3LYP and B3PW91) theory in bulk phase of SnO2 and are compared with its Nano phase. The vibrational frequency pattern in nano phase gets realigned and the frequencies are shifted up to higher region of spectra when compared with bulk phase. The NMR and UV-Visible spectra are simulated and analyzed. Transmittance studies showed that the HOMO-LUMO band gap (Kubo gap) is reduced from 3.47 eV to 3.04 eV while it is heated up to 800°C. The Photoluminescence spectra of SnO2 powder showed a peak shift towards lower energy side with the change of Kubo gap from 3.73 eV to 3.229 eV for as-prepared and heated up to 800°C. PMID:24184584

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

    NASA Astrophysics Data System (ADS)

    Cerussi, Albert Edward

    1999-09-01

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

  2. [The Quantitative Analysis of Raman Spectroscopy to Sulfate Ion in Aqueous Solution].

    PubMed

    Wang, Qian-qian; Sun, Qiang

    2016-02-01

    As a non-destructive and non-contact method, Raman spectroscopy has been widely applied in many research fields. Based on vibrational wavenumber, Raman spectroscopy is usually applied to determine the molecular species. Therefore, Raman quantitative analysis is necessary. In this study, according to the theoretical analysis of Raman intensity, Raman quantitative measurement should be fulfilled by relative intensity ratio, which can be divided into internal and external standards. This eliminates the influence of the measurement conditions. For aqueous solution, it is reasonable to treat the OH stretching band of water as an internal standard to determine the solute concentrations in aqueous solution. The Raman spectra of Na₂SO₄-H₂O, K₂SO₄-H₂O and NaCl-Na₂SO₄-H₂O are recorded in the paper. In addition, the Raman OH stretching band of water can be fitted into two Gaussian sub-bands. The intensity proportion I(SO₄²⁻)/I(W) is used to determine the molarity of sulfate in aqueous solution, where I(SO₄²⁻) represents the intensity of sulfate band and I(W) represents the sum of the two sub-bands of Raman OH stretching bands of water. Therefore, Raman spectroscopy can be utilized to measure the SO₄²⁻concentrations in aqueous solutions. PMID:27209744

  3. Anthropogenic signature of sediment organic matter probed by UV-Visible and fluorescence spectroscopy and the association with heavy metal enrichment.

    PubMed

    He, Wei; Lee, Jong-Hyun; Hur, Jin

    2016-05-01

    Sediment organic matter (SOM) was extracted in an alkaline solution from 43 stream sediments in order to explore the anthropogenic signatures. The SOM spectroscopic characteristics including excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC) were compared for five sampling site groups classified by the anthropogenic variables of land use, population density, the loadings of organics and nutrients, and metal enrichment. The conventional spectroscopic characteristics including specific UV absorbance, absorbance ratio, and humification index did not properly discriminate among the different cluster groups except in the case of metal enrichment. Of the four decomposed PARAFAC components, humic-like and tryptophan-like fluorescence responded negatively and positively, respectively, to increasing degrees of the anthropogenic variables except for land use. The anthropogenic enrichment of heavy metals was positively associated with the abundance of tryptophan-like component. In contrast, humic-like component, known to be mostly responsible for metal binding, exhibited a decreasing trend corresponding with metal enrichment. These conflicting trends can be attributed to the overwhelmed effects of the coupled discharges of heavy metals and organic pollutants into sediments. Our study suggests that the PARAFAC components can be used as functional signatures to probe the anthropogenic influences on sediments. PMID:26901475

  4. Structural Properties and UV-Visible Absorption Spectroscopy of Retinal-pyridyl-CN Re(I) Carbonyl Bipyridine Complex: A Theoretical Study.

    PubMed

    Eng, Julien; Daniel, Chantal

    2015-10-29

    The structural, electronic, and optical properties of the all-trans and five cis conformers of [Re(CO)3(bpy)(ret-pyr-CN)](+) (bpy = 2,2'-bipyridine; ret-pyr-CN = pyridyl-CN-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-2-n)-none-(2,4,6,8-tetraen) were studied in solvent by means of density functional theory (DFT) and time-dependent DFT. The isolated retinal-like chromophore ret-pyr-CN was investigated as well for comparison. By coordination to the complex the two lowest intraligand (IL) states localized on the retinal group are slightly red-shifted from 627 to 690 nm and from 415 to 450 nm, respectively. Several isomerization pathways are open upon irradiation of the Re(I) complex by visible light (400-450 nm), especially to two cis conformers corresponding to the isomerization of the two double bonds of the retinal-like ligand close to the pyridyl group linked to the Re(I) fragment. The metal-to-ligand charge transfer states localized either on the retinal group or on the bpy ligand should play a minor role in the isomerization process itself but could improve its efficiency via ultra-fast intersystem crossing. PMID:26436344

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    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.

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

    ERIC Educational Resources Information Center

    Bazzi, Ali; Kreuz, Bette; Fischer, Jeffrey

    2004-01-01

    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…

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

    ERIC Educational Resources Information Center

    Bazzi, Ali; Kreuz, Bette; Fischer, Jeffrey

    2004-01-01

    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

  8. Diagnosis of nitrosative stress by quantitative EPR-spectroscopy of epidermal cells.

    PubMed

    Petukhov, V I; Baumane, L K; Reste, E D; Zvagule, T Y; Romanova, M A; Shushkevich, N I; Sushkova, L T; Skavronsky, S V; Shchukov, A N

    2013-04-01

    Quantitative assay of nitric oxide (NO) and iron (Fe) was carried out by the electron paramagnetic resonance (EPR) method in epidermal derivative (hair) of 45 liquidators of the Chernobyl accident, 30 employees of radiological institutions having contact with radiation, and 50 students of Vladimir State University, most of which were diagnosed with iron deficiency, namely iron deficiency anemia (4 persons) and latent iron deficiency (34 persons). Measurements were performed on a Radiopan EPR-spectrometer. It was found that the method of quantitative EPR-spectroscopy using diethyldithiocarbamate as a trap in vitro could be successfully used to measure NO-radical activity in such a biological substrate as hair. It was found that the intensity of NO-radical signal in the spectrogram depends on the Fe level (not only in the analyzed substrate, but also in the whole organism). PMID:23658910

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  10. Quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy: 1. Application to sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Thorpe, Michael T.; Rogers, A. Deanne; Bristow, Thomas F.; Pan, Cong

    2015-11-01

    Thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases. With widespread occurrences of sedimentary rocks on the surface of Mars, critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary. Although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials, sedimentary rocks, with natural variation of composition, compaction, and grain size, have yet to be examined. In this work, we present an analysis of the thermal emission spectral (~270-1650 cm-1) characteristics of a suite of 13 sandstones and 14 mudstones. X-ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy. Results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11.2% for detrital grains (i.e., quartz and feldspars) and 14.8% for all other mineral phases present in both sandstones and mudstones, in comparison to common in situ techniques used for determining bulk rock composition. Clay-sized to fine silt-sized grained phase identification is less accurate, with differences from the known ranging from ~5 to 24% on average. Nevertheless, linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks.

  11. Quantitative surface analysis of urban airborne particles by x-ray photoelectron spectroscopy.

    PubMed

    Davide, Atzei; Rossi, Antonella

    2004-03-01

    X-ray photoelectron spectroscopy (XPS) has been used to determine the species present in urban particulate matter collected in the city of Cagliari (Sardinia, Italy) and in an industrial area near to Cagliari. Samples were collected on both cellulose and glass fiber filters. Elemental identification, chemical state and quantitative analyses of the examined samples indicated the presence of Na3AlF6, SiO2 and Al2O3 in the ratio 2:2:5, carbon and oxygen being the major components. The results obtained on NIST SRM 1648 urban particulate matter, before and after grinding, are also presented. PMID:15206834

  12. Quantitative analysis of oils and fats by Fourier transform Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Sadeghi-Jorabchi, H.; Wilson, R. H.; Belton, P. S.; Edwards-Webb, J. D.; Coxon, D. T.

    The rapid analysis of fats and oils is of great importance in the food industry. It is shown that Fourier transform Raman spectroscopy may be used for this purpose. Good quality spectra, free of fluorescence, may be obtained and the spectra may be interpreted in terms of changes in total unsaturation, cis/trans isomer ratios and the number of double bonds in the hydrocarbon chains. Quantitative analysis of total unsaturation and cis/trans is possible and offers considerable improvements in speed when compared with conventional methods.

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

    NASA Astrophysics Data System (ADS)

    Pořízka, P.; Demidov, A.; Kaiser, J.; Keivanian, J.; Gornushkin, I.; Panne, U.; Riedel, J.

    2014-11-01

    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.

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

    SciTech Connect

    Kaoua, Saida; Krimi, Saida; Pechev, Stanislav; Gravereau, Pierre; Chaminade, Jean-Pierre; Couzi, Michel; El Jazouli, Abdelaziz

    2013-02-15

    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.

  15. Characterization of prepared In2O3 thin films: The FT-IR, FT-Raman, UV-Visible investigation and optical analysis.

    PubMed

    Panneerdoss, I Joseph; Jeyakumar, S Johnson; Ramalingam, S; Jothibas, M

    2015-08-01

    In this original work, the Indium oxide (In2O3) thin film is deposited cleanly on microscope glass substrate at different temperatures by spray pyrolysis technique. The physical properties of the films are characterized by XRD, SEM, AFM and AFM measurements. The spectroscopic investigation has been carried out on the results of FT-IR, FT-Raman and UV-Visible. XRD analysis exposed that the structural transformation of films from stoichiometric to non-stoichiometric orientation of the plane vice versa and also found that, the film is polycrystalline in nature having cubic crystal structure with a preferred grain orientation along (222) plane. SEM and AFM studies revealed that, the film with 0.1M at 500°C has spherical grains with uniform dimension. The complete vibrational analysis has been carried out and the optimized parameters are calculated using HF and DFT (CAM-B3LYP, B3LYP and B3PW91) methods with 3-21G(d,p) basis set. Furthermore, NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) technique. The molecular electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, molecular electrostatic potential energy (MEP) analysis and Polarizability first order hyperpolarizability calculations are performed by time dependent DFT (TD-DFT) approach. The energy excitation on electronic structure is investigated and the assignment of the absorption bands in the electronic spectra of steady compound is discussed. The calculated HOMO and LUMO energies showed the enhancement of energy gap by the addition of substitutions with the base molecule. The thermodynamic properties (heat capacity, entropy, and enthalpy) at different temperatures are calculated and interpreted in gas phase. PMID:25827760

  16. Characterization of prepared In2O3 thin films: The FT-IR, FT-Raman, UV-Visible investigation and optical analysis

    NASA Astrophysics Data System (ADS)

    Panneerdoss, I. Joseph; Jeyakumar, S. Johnson; Ramalingam, S.; Jothibas, M.

    2015-08-01

    In this original work, the Indium oxide (In2O3) thin film is deposited cleanly on microscope glass substrate at different temperatures by spray pyrolysis technique. The physical properties of the films are characterized by XRD, SEM, AFM and AFM measurements. The spectroscopic investigation has been carried out on the results of FT-IR, FT-Raman and UV-Visible. XRD analysis exposed that the structural transformation of films from stoichiometric to non-stoichiometric orientation of the plane vice versa and also found that, the film is polycrystalline in nature having cubic crystal structure with a preferred grain orientation along (2 2 2) plane. SEM and AFM studies revealed that, the film with 0.1 M at 500 °C has spherical grains with uniform dimension. The complete vibrational analysis has been carried out and the optimized parameters are calculated using HF and DFT (CAM-B3LYP, B3LYP and B3PW91) methods with 3-21G(d,p) basis set. Furthermore, NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) technique. The molecular electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, molecular electrostatic potential energy (MEP) analysis and Polarizability first order hyperpolarizability calculations are performed by time dependent DFT (TD-DFT) approach. The energy excitation on electronic structure is investigated and the assignment of the absorption bands in the electronic spectra of steady compound is discussed. The calculated HOMO and LUMO energies showed the enhancement of energy gap by the addition of substitutions with the base molecule. The thermodynamic properties (heat capacity, entropy, and enthalpy) at different temperatures are calculated and interpreted in gas phase.

  17. A quantitative appraisal of the binding interactions between an anionic dye, Alizarin Red S, and alkyloxypyridinium surfactants: a detailed micellization, spectroscopic and electrochemical study.

    PubMed

    Sharma, Renu; Kamal, Ajar; Mahajan, Rakesh Kumar

    2016-02-14

    The interactions of an anionic redox-active dye Alizarin Red S (ARS) with novel N-hydroxyethyl-3-alkyloxypyridinium surfactants 1-(2-hydroxyethyl)-3-(tetradecyloxy)pyridinium bromide, [HEC14OPyBr], and 1-(2-hydroxyethyl)-3-(hexadecyloxy)pyridinium bromide, [HEC16OPyBr], were investigated in an aqueous solution for the first time with an attempt to obtain comprehensive knowledge of oppositely charged dye-surfactant mixed systems. Different state-of-the-art techniques viz. conductivity, surface tension (ST), UV-visible spectroscopy, cyclic voltammetry (CV), linear sweep voltammetry (LSV), potentiometry, dynamic light scattering (DLS) and (1)H-NMR analysis have been employed. The presence of ARS decreases the critical micelle concentration (cmc) of alkyloxypyridinium surfactants as the ARS monomers behave as aromatic counterions. A combined analysis of the techniques revealed the existence of cation-π, π-π stacking, H-bonding, electrostatic and hydrophobic interactions among ARS and alkyloxypyridinium surfactants. A quantitative appraisal of the process of interaction among ARS and alkyloxypyridinium surfactants has been made in terms of various micellar, binding and electrochemical parameters evaluated using ST, UV-visible and voltammetric measurements. Also, the results extracted from (1)H-NMR and voltammetric measurements indicate that the catechol moiety of ARS is involved in the binding mechanism among ARS and alkyloxypyridinium surfactants. PMID:26727388

  18. H2o Quantitative Analysis of Transition Zone Minerals Wadsleyite and Ringwoodite By Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Novella, D.; Bolfan-Casanova, N.; Bureau, H.; Raepsaet, C.; Montagnac, G.

    2014-12-01

    Liquid H2O covers approximately 70% of the Earth's surface but it can also be incorporated as OH- groups in nominally anhydrous minerals (NAMs) that constitute the Earth's mantle, as observed in peridotitic xenoliths. The presence of even trace amounts (ppm wt) of hydrogen in mantle minerals strongly affect the physical, chemical and rheological properties of the mantle. The Earth's transition zone (410 to 660 km depth) is particularly important in this regard since it can store large amounts of H2O (wt%) as shown by experiments and recently by a natural sample. Addressing the behavior of H2O at high depths and its potential concentration in mantle NAMs is therefore fundamental to fully comprehend global-scale processes such as plate tectonics and magmatism. We developed an innovative technique to measure the H2O content of main transition zone NAMs wadsleyite and ringwoodite by Raman spectroscopy. This technique allows to use a beam of 1-3 µm size to measure small samples that are typical for high pressure natural and synthetic specimens. High pressure polyphasic samples are indeed very challenging to be measured in terms of H2O content by the routinely used Fourier transform infra-red (FTIR) spectroscopy and ion probe mass spectroscopy analyses, making the Raman approach a valid alternative. High quality crystals of wadsleyite and ringwoodite were synthesized at high pressure and temperature in a multi-anvil press and analyzed by Raman and FTIR spectroscopy as well as elastic recoil detection analyses (ERDA) which is an absolute, standard-free technique. We will present experimental data that allow to apply Raman spectroscopy to the determination of H2O content of the most abundant minerals in the transition zone. The data gathered in this study will also permit to investigate the absorption coefficients of wadsleyite and ringwoodite that are employed in FTIR quantitative analyses.

  19. Quantitative laser-induced breakdown spectroscopy analysis of calcified tissue samples

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  20. Quantitative analyses of tartaric acid based on terahertz time domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Cao, Binghua; Fan, Mengbao

    2010-10-01

    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.

  1. Monitoring lactic acid production during milk fermentation by in situ quantitative proton nuclear magnetic resonance spectroscopy.

    PubMed

    Bouteille, R; Gaudet, M; Lecanu, B; This, H

    2013-04-01

    When fermenting milk, lactic bacteria convert part of α- and β-lactoses into d- and l- lactic acids, causing a pH decrease responsible for casein coagulation. Lactic acid monitoring during fermentation is essential for the control of dairy gel textural and organoleptic properties, and is a way to evaluate strain efficiency. Currently, titrations are used to follow the quantity of acids formed during jellification of milk but they are not specific to lactic acid. An analytical method without the use of any reagent was investigated to quantify lactic acid during milk fermentation: in situ quantitative proton nuclear magnetic resonance spectroscopy. Two methods using in situ quantitative proton nuclear magnetic resonance spectroscopy were compared: (1) d- and l-lactic acids content determination, using the resonance of their methyl protons, showing an increase from 2.06 ± 0.02 to 8.16 ± 0.74 g/L during 240 min of fermentation; and (2) the determination of the α- and β-lactoses content, decreasing from 42.68 ± 0.02 to 30.76 ± 1.75 g/L for the same fermentation duration. The ratio between the molar concentrations of produced lactic acids and consumed lactoses enabled cross-validation, as the value (2.02 ± 0.18) is consistent with lactic acid bacteria metabolism. PMID:23403188

  2. Quantitative portable gamma spectroscopy sample analysis for non-standard sample geometries

    SciTech Connect

    Enghauser, M.W.; Ebara, S.B.

    1997-04-01

    Utilizing a portable spectroscopy system, a quantitative method for analysis of samples containing a mixture of fission and activation products in nonstandard geometries was developed. The method can be used with various sample and shielding configurations where analysis on a laboratory based gamma spectroscopy system is impractical. The portable gamma spectroscopy method involves calibration of the detector and modeling of the sample and shielding to identify and quantify the radionuclides present in the sample. The method utilizes the intrinsic efficiency of the detector and the unattenuated gamma fluence rate at the detector surface per unit activity from the sample to calculate the nuclide activity and Minimum Detectable Activity (MDA). For a complex geometry, a computer code written for shielding applications (MICROSHIELD) is utilized to determine the unattenuated gamma fluence rate per unit activity at the detector surface. Lastly, the method is only applicable to nuclides which emit gamma rays and cannot be used for pure beta emitters. In addition, if sample self absorption and shielding is significant, the attenuation will result in high MDA`s for nuclides which solely emit low energy gamma rays. The following presents the analysis technique and presents verification results demonstrating the accuracy of the method.

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

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    PubMed

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

    2013-09-17

    Nuclear magnetic resonance (NMR) spectroscopy is a widely used technique for mixture analysis, but it has shortcomings in resolving carbohydrate mixtures due to the narrow chemical shift range of glycans in general and fragments of homopolymers in particular. Here, we suggest a protocol toward fast spectroscopic glycan mixture analysis. We show that a plethora of oligosaccharides comprising only α-glucopyranosyl residues can be resolved into distinct quantifiable signals with NMR experiments that are substantially faster than chromatographic runs. Conceptually, the approach fully exploits the narrow line widths of glycans (ν1/2 < 3 Hz) in the (13)C spectral dimension while disregarding superfluous spectral information in compound identification and quantitation. The acetal (H1C1) groups suffice to spectroscopically resolve ∼20 different starch fragments in optimized (1)H-(13)C NMR with a narrow (13)C spectral width (3 ppm) that allows sampling the indirect (13)C dimension at high resolution within 15 min. Rapid quantitations by high-resolution NMR data are achieved for glycans at concentrations as low as 10 μg/mL. For validation, comparisons were made with quantitations obtained by more time-consuming chromatographic methods and yielded coefficients of determination (R(2)) above 0.99. PMID:23952648

  6. Quantitative determination of toxic metals in soil by laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Jisong; Zhou, Weidong; Ying, Chaofu; Chen, Qiaoling

    2008-12-01

    Laser-induced breakdown spectroscopy (LIBS) is a promising technique for in situ environmental analysis. The potential of this technique for accurate quantitative analysis of heavy metals in soil could be greatly improved by optimized the time delay, laser energy, working distance, et. and by analyzing the results with a procedure which overcomes the problem related to the physical character of soil sample. A LIBS system for soil analysis is reported here. The optimum experimental conditions for quantitatively measurement of Sr and other heavy metals in soil are presented. A new data acquisition and statistical method has been used to analyze the recorded spectra. The precision of this method, in terms of relative standard deviation (RSD), is of 7 % for Sr I 460.73 nm. The calibration curve for quantitative measurement of Sr has been built. From the calibration curves, the detection limits of Sr in soil were determined to be 15.0 µg/g, and are better than the data reported in literature.

  7. Quantitative confocal fluorescence microscopy of dynamic processes by multifocal fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Krmpot, Aleksandar J.; Nikolić, Stanko N.; Vitali, Marco; Papadopoulos, Dimitrios K.; Oasa, Sho; Thyberg, Per; Tisa, Simone; Kinjo, Masataka; Nilsson, Lennart; Gehring, Walter J.; Terenius, Lars; Rigler, Rudolf; Vukojevic, Vladana

    2015-07-01

    Quantitative confocal fluorescence microscopy imaging without scanning is developed for the study of fast dynamical processes. The method relies on the use of massively parallel Fluorescence Correlation Spectroscopy (mpFCS). Simultaneous excitation of fluorescent molecules across the specimen is achieved by passing a single laser beam through a Diffractive Optical Element (DOE) to generate a quadratic illumination matrix of 32×32 light sources. Fluorescence from 1024 illuminated spots is detected in a confocal arrangement by a matching matrix detector consisting of the same number of single-photon avalanche photodiodes (SPADs). Software was developed for data acquisition and fast autoand cross-correlation analysis by parallel signal processing using a Graphic Processing Unit (GPU). Instrumental performance was assessed using a conventional single-beam FCS instrument as a reference. Versatility of the approach for application in biomedical research was evaluated using ex vivo salivary glands from Drosophila third instar larvae expressing a fluorescently-tagged transcription factor Sex Combs Reduced (Scr) and live PC12 cells stably expressing the fluorescently tagged mu-opioid receptor (MOPeGFP). We show that quantitative mapping of local concentration and mobility of transcription factor molecules across the specimen can be achieved using this approach, which paves the way for future quantitative characterization of dynamical reaction-diffusion landscapes across live cells/tissue with a submillisecond temporal resolution (presently 21 μs/frame) and single-molecule sensitivity.

  8. Quantitative neuropathology by high resolution magic angle spinning proton magnetic resonance spectroscopy

    PubMed Central

    Cheng, L. L.; Ma, M. J.; Becerra, L.; Ptak, T.; Tracey, I.; Lackner, A.; González, R. G.

    1997-01-01

    We describe a method that directly relates tissue neuropathological analysis to medical imaging. Presently, only indirect and often tenuous relationships are made between imaging (such as MRI or x-ray computed tomography) and neuropathology. We present a biochemistry-based, quantitative neuropathological method that can help to precisely quantify information provided by in vivo proton magnetic resonance spectroscopy (1HMRS), an emerging medical imaging technique. This method, high resolution magic angle spinning (HRMAS) 1HMRS, is rapid and requires only small amounts of unprocessed samples. Unlike chemical extraction or other forms of tissue processing, this method analyzes tissue directly, thus minimizing artifacts. We demonstrate the utility of this method by assessing neuronal damage using multiple tissue samples from differently affected brain regions in a case of Pick disease, a human neurodegenerative disorder. Among different regions, we found an excellent correlation between neuronal loss shown by traditional neurohistopathology and decrease of the neuronal marker N-acetylaspartate measured by HRMAS 1HMRS. This result demonstrates for the first time, to our knowledge, a direct, quantitative link between a decrease in N-acetylaspartate and neuronal loss in a human neurodegenerative disease. As a quantitative method, HRMAS 1HMRS has potential applications in experimental and clinical neuropathologic investigations. It should also provide a rational basis for the interpretation of in vivo 1HMRS studies of human neurological disorders. PMID:9177231

  9. Toward quantitative deuterium analysis with laser-induced breakdown spectroscopy using atmospheric-pressure helium gas

    SciTech Connect

    Hedwig, Rinda; Lie, Zener Sukra; Kurniawan, Koo Hendrik; Kagawa, Kiichiro; Tjia, May On

    2010-01-15

    An experimental study has been carried out for the development of quantitative deuterium analysis using the neodymium doped yttrium aluminum garnet laser-induced breakdown spectroscopy (LIBS) with atmospheric pressure surrounding He gas by exploring the appropriate experimental condition and special sample cleaning technique. The result demonstrates the achievement of a full resolution between the D and H emission lines from zircaloy-4 samples, which is prerequisite for the desired quantitative analysis. Further, a linear calibration line with zero intercept was obtained for the emission intensity of deuterium from a number of zircaloy samples doped with predetermined concentrations of deuterium. The result is obtained by setting a +4 mm defocusing position for the laser beam, 6 {mu}s detection gating time, and 7 mm imaging position of the plasma for the detection, which is combined with a special procedure of repeated laser cleaning of the samples. This study has thus provided the basis for the development of practical quantitative deuterium analysis by LIBS.

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

    NASA Astrophysics Data System (ADS)

    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

    We report here on two stable polymorphs of the dinuclear complex [Re2(μ-Cl)2(CO)6(μ-4,5- (Me3Si)2pyridazine)]. The compound belongs to the recently reported class of dinuclear luminescent Re(I) complexes of general formula [Re2(μ-Cl)2(CO)6(μ-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, π-π 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(μ-Cl)2(CO)6 (μ-4,5-(Me3Si)2pyridazine)].

  11. UV/visible and surface-enhanced infrared studies of polyethylene/oriented gold nanoparticle composite films: The effects of gold particle size, shape, and orientation

    NASA Astrophysics Data System (ADS)

    Al-Rawashdeh, Nathir A. F.

    We have succeeded in preparing gold rods of high aspect ratio (>6) and diameter ca. ≈32 nm, using anodically grown alumina films as host templates. To evaluate the sample quality, the plasmon resonance spectra of alumina/gold nanoparticle composite films were measured. In general, we found that the plasmon resonance maxima and intensity are dependent on the size, shape, and orientation of the gold nanoparticle. Furthermore, we have succeeded in orienting such nanoparticles in polyethylene matrices, and confirmed the net orientation via polarization studies in the UV/Visible/Near-IR region of the spectrum. In the polarization studies, we found that the extent of red-shift and damping of the plasmon resonance band are dependent on the size, shape, and orientation of the gold nanoparticle. The effects of gold particle size, shape, and orientation on the plasmon resonance spectra of polyethylene/oriented gold particle composite films have been compared to the predictions of Rayleigh scattering theory and effective medium theories (Maxwell-Garnett (MG) and Bruggeman (BRG)). From the comparison of the experimental plasmon resonance spectra with the calculated spectra using the above theories, we found that the best model for predicting the experimental plasmon resonance band shape and intensity is the BRG treatment. That finding has implications for what the sample is like. After we confirmed the net orientation of the nanoparticles in polyethylene matrices, we examined the infrared-transmittance spectra of 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) chemically bonded on such composite films via polarization studies. In general, we found that the IR-transmittance spectra of MPA and MUA show a polarization angle dependence. We discuss the effects of the gold particle shape, and orientation in the incident field on electromagnetic (EM) enhancements as seen in our oriented gold rod composite studies, in the context of the effective medium type theories for EM enhancements. From these studies, we found that the polarization infrared spectra of these IR-probe species show a polarization angle dependence that is consistent with the effective medium theories for EM spectral enhancements. Our conclusion is that a small enhancement in the intensity of the IR-probe is attributable to an EM enhancement. Large enhancements (ca. 500-fold) seen on previous studies are likely due to chemical effects (such as a charge transfer between the molecule and the metal particle).

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

    SciTech Connect

    Mann, C.K.; Vickers, T.J.

    1994-10-11

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  14. Quantitative laser-induced breakdown spectroscopy of standard reference materials of various categories

    NASA Astrophysics Data System (ADS)

    Choi, Soo-Jin; Lee, Kang-Jae; Yoh, Jack J.

    2013-12-01

    The quantitative laser-induced breakdown spectroscopy analysis was carried out with standard reference materials (SRM). In order to minimize errors due to the matrix effect, we used 21 SRM samples that belong to different categories of food, clay, sludge, steelmaking alloy, and geochemical and agricultural materials. The principal component analysis was used for rapid identification and discrimination of the samples. Nine elements (Al, Ca, Mg, Ti, Si, Fe, K, Na, and Mn) in each sample were analyzed. While each category of samples shows a specific tendency in the calibration curves of Na, Ti, Si, Al, Fe, and Mn, other elements (K, Ca, and Mg) do not pose any noticeable similarity. The present results establish benchmark calibration curves for characterizing various SRMs.

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

    PubMed

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

    2011-01-01

    (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 11α,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 11α,13-dihydrohelenalin esters separately. Furthermore, 6-O-tigloylhelenalin (HT, 1), 6-O-methacryloylhelenalin (HM, 2), 6-O-tigloyl-11α,13-dihydrohelenalin (DHT, 5), and 6-O-methacryloyl-11α,13-dihydrohelenalin (DHM, 6) were quantified as individual components. PMID:20837387

  16. Quantitative characterization of traumatic bruises by combined pulsed photothermal radiometry and diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Vidovič, Luka; Milanič, Matija; Randeberg, Lise L.; Majaron, Boris

    2015-02-01

    We apply diffuse reflectance spectroscopy (DRS) and pulsed photothermal radiometry (PPTR) for characterization of the bruise evolution process. While DRS provides information in a wide range of visible wavelengths, the PPTR enables extraction of detailed depth distribution and concentration profiles of selected absorbers (e.g. melanin, hemoglobin). In this study, we simulate experimental DRS spectra and PPTR signals using the Monte Carlo technique and focus on characterization of a suitable fitting approach for their analysis. We find inverse Monte Carlo to be superior to the diffusion approximation approach for the inverse analysis of DRS spectra. The analysis is then augmented with information obtainable by the fitting of the PPTR signal. We show that both techniques can be coupled in a combined fitting approach. The combining of two complementary techniques improves the robustness and accuracy of the inverse analysis, enabling a comprehensive quantitative characterization of the bruise evolution dynamics.

  17. The use of FTIR spectroscopy to assess quantitative changes in the biochemical composition of microalgae.

    PubMed

    Wagner, Heiko; Liu, Zhixin; Langner, Uwe; Stehfest, Katja; Wilhelm, Christian

    2010-08-01

    A mid-infrared spectroscopic method was developed for the simultaneous and quantitative determination of total protein, carbohydrate and lipid contents of microalgal cells. Based on a chemometric approach, measured FTIR (Fourier transform infrared) spectra from algal cells were reconstructed by a partial least square algorithm, using the spectra of the reference substances to determine their relative contribution to the overall cell spectrum. From this specific absorption, absolute macromolecular cell composition [pg cell(-1)] can be calculated using calibration curves, which have been validated by independent biochemical methods. The future potential of this method for photosynthesis research is shown by its application to follow time-resolved changes in the cellular composition of microalgae during an illumination period of several hours. We show how the macromolecular composition can be investigated by FTIR spectroscopy methods. This can substantially increase the efficiency of screening processes like bioreactor monitoring and may be beneficial in metabolic engineering of algal cells. PMID:20503222

  18. In situ semi-quantitative analysis of polluted soils by laser-induced breakdown spectroscopy (LIBS).

    PubMed

    Ismaël, Amina; Bousquet, Bruno; Michel-Le Pierrès, Karine; Travaillé, Grégoire; Canioni, Lionel; Roy, Stéphane

    2011-05-01

    Time-saving, low-cost analyses of soil contamination are required to ensure fast and efficient pollution removal and remedial operations. In this work, laser-induced breakdown spectroscopy (LIBS) has been successfully applied to in situ analyses of polluted soils, providing direct semi-quantitative information about the extent of pollution. A field campaign has been carried out in Brittany (France) on a site presenting high levels of heavy metal concentrations. Results on iron as a major component as well as on lead and copper as minor components are reported. Soil samples were dried and prepared as pressed pellets to minimize the effects of moisture and density on the results. LIBS analyses were performed with a Nd:YAG laser operating at 1064 nm, 60 mJ per 10 ns pulse, at a repetition rate of 10 Hz with a diameter of 500 μm on the sample surface. Good correlations were obtained between the LIBS signals and the values of concentrations deduced from inductively coupled plasma atomic emission spectroscopy (ICP-AES). This result proves that LIBS is an efficient method for optimizing sampling operations. Indeed, "LIBS maps" were established directly on-site, providing valuable assistance in optimizing the selection of the most relevant samples for future expensive and time-consuming laboratory analysis and avoiding useless analyses of very similar samples. Finally, it is emphasized that in situ LIBS is not described here as an alternative quantitative analytical method to the usual laboratory measurements but simply as an efficient time-saving tool to optimize sampling operations and to drastically reduce the number of soil samples to be analyzed, thus reducing costs. The detection limits of 200 ppm for lead and 80 ppm for copper reported here are compatible with the thresholds of toxicity; thus, this in situ LIBS campaign was fully validated for these two elements. Consequently, further experiments are planned to extend this study to other chemical elements and other matrices of soils. PMID:21513588

  19. Identification and quantitation of xenobiotics by 1H NMR spectroscopy in poisoning cases.

    PubMed

    Imbenotte, M; Azaroual, N; Cartigny, B; Vermeersch, G; Lhermitte, M

    2003-04-23

    In order to analyse a wide range of xenobiotics and their metabolites present in biological fluids, NMR spectroscopy can be used. A large variety of xenobiotics (therapeutic agents, pesticides, solvents, alcohols) can be characterized and quantitated directly, without sample preparation. NMR investigations were applied to acute poisoning cases, involving drugs such as salicylates and valproic acid (VPA). In a salicylate poisoning case, the three major metabolites of acetylsalicylic acid have been detected in crude urine, and rapid identification of lysine revealed the origin of the intoxication, namely lysine acetylsalicylate (Aspegic). Valproic acid as its glucuronide was identified in urine samples from two poisoned patients. 1H NMR was also used to identify and quantitate paraquat (Gramoxone) in urine owing to its two aromatic signals at 8.49 and 9.02 ppm, in two acutely poisoned patients (183 and 93 mg/l). An intentional poisoning case with tetrahydrofuran (THF) was also investigated. Serum and urine samples were collected. THF was characterized by its resonances at 1.90 and 3.76 ppm, and quantified at 813 and 850 mg/l in the two biological fluids, respectively. Moreover, two other compounds were detected: lactate and gamma-hydroxybutyric acid (GHB). 1H NMR spectroscopic analysis of serum samples from three poisoned patients revealed methanol in one case and ethylene glycol in the two others. Moreover, in the same spectrum, the corresponding metabolites formate and glycolate were found. Compared with the reference chromatographic or spectrophotometric methods, requiring time-consuming extraction and/or derivatization steps, NMR spectroscopy allows the determination of many exogenous and endogenous compounds, without any pre-selection of the analytes. PMID:12742700

  20. Characterization of geometrical factors for quantitative angle-resolved photoelectron spectroscopy

    SciTech Connect

    Martinez, Eugenie; Herrera-Gomez, Alberto; Allain, Mickael; Renault, Olivier; Faure, Alain; Chabli, Amal; Bertin, Francois

    2012-07-15

    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.

  1. Raman spectroscopy of human skin: looking for a quantitative algorithm to reliably estimate human age.

    PubMed

    Pezzotti, Giuseppe; Boffelli, Marco; Miyamori, Daisuke; Uemura, Takeshi; Marunaka, Yoshinori; Zhu, Wenliang; Ikegaya, Hiroshi

    2015-06-01

    The possibility of examining soft tissues by Raman spectroscopy is challenged in an attempt to probe human age for the changes in biochemical composition of skin that accompany aging. We present a proof-of-concept report for explicating the biophysical links between vibrational characteristics and the specific compositional and chemical changes associated with aging. The actual existence of such links is then phenomenologically proved. In an attempt to foster the basics for a quantitative use of Raman spectroscopy in assessing aging from human skin samples, a precise spectral deconvolution is performed as a function of donors' ages on five cadaveric samples, which emphasizes the physical significance and the morphological modifications of the Raman bands. The outputs suggest the presence of spectral markers for age identification from skin samples. Some of them appeared as authentic "biological clocks" for the apparent exactness with which they are related to age. Our spectroscopic approach yields clear compositional information of protein folding and crystallization of lipid structures, which can lead to a precise identification of age from infants to adults. Once statistically validated, these parameters might be used to link vibrational aspects at the molecular scale for practical forensic purposes. PMID:26112367

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

    PubMed

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

    2011-03-01

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

  3. Raman spectroscopy of human skin: looking for a quantitative algorithm to reliably estimate human age

    NASA Astrophysics Data System (ADS)

    Pezzotti, Giuseppe; Boffelli, Marco; Miyamori, Daisuke; Uemura, Takeshi; Marunaka, Yoshinori; Zhu, Wenliang; Ikegaya, Hiroshi

    2015-06-01

    The possibility of examining soft tissues by Raman spectroscopy is challenged in an attempt to probe human age for the changes in biochemical composition of skin that accompany aging. We present a proof-of-concept report for explicating the biophysical links between vibrational characteristics and the specific compositional and chemical changes associated with aging. The actual existence of such links is then phenomenologically proved. In an attempt to foster the basics for a quantitative use of Raman spectroscopy in assessing aging from human skin samples, a precise spectral deconvolution is performed as a function of donors' ages on five cadaveric samples, which emphasizes the physical significance and the morphological modifications of the Raman bands. The outputs suggest the presence of spectral markers for age identification from skin samples. Some of them appeared as authentic "biological clocks" for the apparent exactness with which they are related to age. Our spectroscopic approach yields clear compositional information of protein folding and crystallization of lipid structures, which can lead to a precise identification of age from infants to adults. Once statistically validated, these parameters might be used to link vibrational aspects at the molecular scale for practical forensic purposes.

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

    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.

  6. Quantitative Analysis of Mg in Pipeline Dirt Based on Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Shaolong; Wang, Yangen; Chen, Shanjun; Chen, Qi

    2015-08-01

    In order to maintain the pipeline better and remove the dirt more effectively, it was necessary to analyze the contents of elements in dirt. Mg in soil outside of the pipe and the dirt inside of the pipe was quantitatively analyzed and compared by using the laser-induced breakdown spectroscopy (LIBS). Firstly, Mg was quantitatively analyzed on the basis of Mg I 285.213 nm by calibration curve for integrated intensity and peak intensity of the spectrum before and after subtracting noise, respectively. Then calibration curves on the basis of Mg II 279.553 nm and Mg II 280.270 nm were analyzed. The results indicated that it is better to use integrated intensity after subtracting noise of the spectrum line with high relative intensity to make the calibration curve. supported partly by the Natural Science Foundation of Hubei Province, China (No. 2012FFB00105) and partly by the Science Research Program of Education Department of Hubei Province, China (No. B2013288)

  7. A quantitative analysis of elements in soil using laser-induced breakdown spectroscopy technique

    NASA Astrophysics Data System (ADS)

    He, G.-C.; Sun, D.-X.; Su, M.-G.; Dong, C.-Z.

    2011-09-01

    Laser-induced breakdown spectroscopy (LIBS) was applied to the quantitative analysis of elemental composition of soil. The experiment was performed in air at atmospheric pressure and at room temperature. A Nd:YAG laser with the fundamental wavelength of 1064 nm was employed to generate the soil plasma. The emission spectra from the plasma were collected by the Cerny-Turner type of spectrometer, which was equipped with an intensified charge-coupled device (ICCD). The plasma temperature and electron density were evaluated by the Boltzmann plot method and the Saha-Boltzmann equation respectively. Then the concentrations of elements in soil were further obtained by the internal standard of iron element and some selected atomic/ionic lines. In order to prove the credibility and reliability of the present LIBS results, a comparison between the LIBS results and the nominal concentrations was performed. It was found that the LIBS results agree with the nominal concentrations. Therefore the LIBS technique promises to fast and in simultaneous multi-element quantitative analysis of soil.

  8. Quantitatively Resolving Ligand–Receptor Bonds on Cell Surfaces Using Force-Induced Remnant Magnetization Spectroscopy

    PubMed Central

    2016-01-01

    Molecule-specific noncovalent bonding on cell surfaces is the foundation for cellular recognition and functioning. A major challenge in probing these bonds is to resolve the specific bonds quantitatively and efficiently from the nonspecific interactions in a complex environment. Using force-induced remnant magnetization spectroscopy (FIRMS), we were able to resolve quantitatively three different interactions for magnetic beads bearing anti-CD4 antibodies with CD4+ T cell surfaces based upon their binding forces. The binding force of the CD4 antibody–antigen bonds was determined to be 75 ± 3 pN. For comparison, the same bonds were also studied on a functionalized substrate surface, and the binding force was determined to be 90 ± 6 pN. The 15 pN difference revealed by high-resolution FIRMS illustrates the significant impact of the bonding environment. Because the force difference was unaffected by the cell number or the receptor density on the substrate, we attributed it to the possible conformational or local environmental differences of the CD4 antigens between the cell surface and substrate surface. Our results show that the high force resolution and detection efficiency afforded by FIRMS are valuable for studying protein–protein interactions on cell surfaces. PMID:27163031

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  10. A novel rapid quantitative analysis of drug migration on tablets using laser induced breakdown spectroscopy.

    PubMed

    Yokoyama, Makoto; Tourigny, Martine; Moroshima, Kenji; Suzuki, Junsuke; Sakai, Miyako; Iwamoto, Kiyoshi; Takeuchi, Hirofumi

    2010-11-01

    There have been few reports wherein drug migration from the interior to the surface of a tablet has been analyzed quantitatively until now. In this paper, we propose a novel, rapid, quantitative analysis of drug migration in tablets using laser induced breakdown spectroscopy (LIBS). To evaluate drug migration, model tablets containing nicardipine hydrochloride as active pharmaceutical ingredient (API) were prepared by a conventional wet granulation method. Since the color of this API is pale yellow and all excipients are white, we can observe the degree of drug migration by visual inspection in these model tablets. In order to prepare tablets with different degrees of drug migration, the temperature of the drying process after tableting was varied between 50 to 80 °C. Using these manifold tablets, visual inspection, Fourier transform (FT)-IR mapping and LIBS analysis were carried out to evaluate the drug migration in the tablets. While drug migration could be observed using all methods, only LIBS analysis could provide quantitative analysis wherein the average LIBS intensity was correlated with the degree of drug migration obtained from the drying temperature. Moreover, in this work, we compared the sample preparation, data analysis process and measurement time for visual inspection, FT-IR mapping and LIBS analysis. The results of the comparison between these methods demonstrated that LIBS analysis is the simplest and the fastest method for migration monitoring. From the results obtained, we conclude that LIBS analysis is one of most useful process analytical technology (PAT) tools to solve the universal migration problem. PMID:21048347

  11. Semi-quantitative prediction of a multiple API solid dosage form with a combination of vibrational spectroscopy methods.

    PubMed

    Hertrampf, A; Sousa, R M; Menezes, J C; Herdling, T

    2016-05-30

    Quality control (QC) in the pharmaceutical industry is a key activity in ensuring medicines have the required quality, safety and efficacy for their intended use. QC departments at pharmaceutical companies are responsible for all release testing of final products but also all incoming raw materials. Near-infrared spectroscopy (NIRS) and Raman spectroscopy are important techniques for fast and accurate identification and qualification of pharmaceutical samples. Tablets containing two different active pharmaceutical ingredients (API) [bisoprolol, hydrochlorothiazide] in different commercially available dosages were analysed using Raman- and NIR Spectroscopy. The goal was to define multivariate models based on each vibrational spectroscopy to discriminate between different dosages (identity) and predict their dosage (semi-quantitative). Furthermore the combination of spectroscopic techniques was investigated. Therefore, two different multiblock techniques based on PLS have been applied: multiblock PLS (MB-PLS) and sequential-orthogonalised PLS (SO-PLS). NIRS showed better results compared to Raman spectroscopy for both identification and quantitation. The multiblock techniques investigated showed that each spectroscopy contains information not present or captured with the other spectroscopic technique, thus demonstrating that there is a potential benefit in their combined use for both identification and quantitation purposes. PMID:26970593

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

    ERIC Educational Resources Information Center

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

    2006-01-01

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

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

    PubMed

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

    2012-09-01

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

  14. [Quantitative analysis of thiram by surface-enhanced raman spectroscopy combined with feature extraction Algorithms].

    PubMed

    Zhang, Bao-hua; Jiang, Yong-cheng; Sha, Wen; Zhang, Xian-yi; Cui, Zhi-feng

    2015-02-01

    Three feature extraction algorithms, such as the principal component analysis (PCA), the discrete cosine transform (DCT) and the non-negative factorization (NMF), were used to extract the main information of the spectral data in order to weaken the influence of the spectral fluctuation on the subsequent quantitative analysis results based on the SERS spectra of the pesticide thiram. Then the extracted components were respectively combined with the linear regression algorithm--the partial least square regression (PLSR) and the non-linear regression algorithm--the support vector machine regression (SVR) to develop the quantitative analysis models. Finally, the effect of the different feature extraction algorithms on the different kinds of the regression algorithms was evaluated by using 5-fold cross-validation method. The experiments demonstrate that the analysis results of SVR are better than PLSR for the non-linear relationship between the intensity of the SERS spectrum and the concentration of the analyte. Further, the feature extraction algorithms can significantly improve the analysis results regardless of the regression algorithms which mainly due to extracting the main information of the source spectral data and eliminating the fluctuation. Additionally, PCA performs best on the linear regression model and NMF is best on the non-linear model, and the predictive error can be reduced nearly three times in the best case. The root mean square error of cross-validation of the best regression model (NMF+SVR) is 0.0455 micormol x L(-1) (10(-6) mol x L(-1)), and it attains the national detection limit of thiram, so the method in this study provides a novel method for the fast detection of thiram. In conclusion, the study provides the experimental references the selecting the feature extraction algorithms on the analysis of the SERS spectrum, and some common findings of feature extraction can also help processing of other kinds of spectroscopy. PMID:25970898

  15. Quantitative Fluorescence Studies in Living Cells: Extending Fluorescence Fluctuation Spectroscopy to Peripheral Membrane Proteins

    NASA Astrophysics Data System (ADS)

    Smith, Elizabeth Myhra

    The interactions of peripheral membrane proteins with both membrane lipids and proteins are vital for many cellular processes including membrane trafficking, cellular signaling, and cell growth/regulation. Building accurate biophysical models of these processes requires quantitative characterization of the behavior of peripheral membrane proteins, yet methods to quantify their interactions inside living cells are very limited. Because peripheral membrane proteins usually exist both in membrane-bound and cytoplasmic forms, the separation of these two populations is a key challenge. This thesis aims at addressing this challenge by extending fluorescence fluctuation spectroscopy (FFS) to simultaneously measure the oligomeric state of peripheral membrane proteins in the cytoplasm and at the plasma membrane. We developed a new method based on z-scan FFS that accounts for the fluorescence contributions from cytoplasmic and membrane layers by incorporating a fluorescence intensity z-scan through the cell. H-Ras-EGFP served as a model system to demonstrate the feasibility of the technique. The resolvability and stability of z-scanning was determined as well as the oligomeric state of H-Ras-EGFP at the plasma membrane and in the cytoplasm. Further, we successfully characterized the binding affinity of a variety of proteins to the plasma membrane by quantitative analysis of the z-scan fluorescence intensity profile. This analysis method, which we refer to as z-scan fluorescence profile deconvoution, was further used in combination with dual-color competition studies to determine the lipid specificity of protein binding. Finally, we applied z-scan FFS to provide insight into the early assembly steps of the HTLV-1 retrovirus.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  17. Application of short-wave infrared (SWIR) spectroscopy in quantitative estimation of clay mineral contents

    NASA Astrophysics Data System (ADS)

    You, Jinfeng; Xing, Lixin; Liang, Liheng; Pan, Jun; Meng, Tao

    2014-03-01

    Clay minerals are significant constituents of soil which are necessary for life. This paper studied three types of clay minerals, kaolinite, illite, and montmorillonite, for they are not only the most common soil forming materials, but also important indicators of soil expansion and shrinkage potential. These clay minerals showed diagnostic absorption bands resulting from vibrations of hydroxyl groups and structural water molecules in the SWIR wavelength region. The short-wave infrared reflectance spectra of the soil was obtained from a Portable Near Infrared Spectrometer (PNIS, spectrum range: 1300~2500 nm, interval: 2 nm). Due to the simplicity, quickness, and the non-destructiveness analysis, SWIR spectroscopy has been widely used in geological prospecting, chemical engineering and many other fields. The aim of this study was to use multiple linear regression (MLR) and partial least squares (PLS) regression to establish the optimizing quantitative estimation models of the kaolinite, illite and montmorillonite contents from soil reflectance spectra. Here, the soil reflectance spectra mainly refers to the spectral reflectivity of soil (SRS) corresponding to the absorption-band position (AP) of kaolinite, illite, and montmorillonite representative spectra from USGS spectral library, the SRS corresponding to the AP of soil spectral and soil overall spectrum reflectance values. The optimal estimation models of three kinds of clay mineral contents showed that the retrieval accuracy was satisfactory (Kaolinite content: a Root Mean Square Error of Calibration (RMSEC) of 1.671 with a coefficient of determination (R2) of 0.791; Illite content: a RMSEC of 1.126 with a R2 of 0.616; Montmorillonite content: a RMSEC of 1.814 with a R2 of 0.707). Thus, the reflectance spectra of soil obtained form PNIS could be used for quantitative estimation of kaolinite, illite and montmorillonite contents in soil.

  18. Quantitative FT-IR spectroscopy of gypsum raw material for industry

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    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.

  19. Hemoglobin consumption by P. falciparum in individual erythrocytes imaged via quantitative phase spectroscopy

    PubMed Central

    Rinehart, Matthew T.; Park, Han Sang; Walzer, Katelyn A.; Chi, Jen-Tsan Ashley; Wax, Adam

    2016-01-01

    Plasmodium falciparum infection causes structural and biochemical changes in red blood cells (RBCs). To quantify these changes, we apply a novel optical technique, quantitative phase spectroscopy (QPS) to characterize individual red blood cells (RBCs) during the intraerythrocytic life cycle of P. falciparum. QPS captures hyperspectral holograms of individual RBCs to measure spectroscopic changes across the visible wavelength range (475–700 nm), providing complex information, i.e. amplitude and phase, about the light field which has interacted with the cell. The complex field provides complimentary information on hemoglobin content and cell mass, which are both found to dramatically change upon infection by P. falciparum. Hb content progressively decreases with parasite life cycle, with an average 72.2% reduction observed for RBCs infected by schizont-stage P. falciparum compared to uninfected cells. Infection also resulted in a 33.1% reduction in RBC’s optical volume, a measure of the cells’ non-aqueous components. Notably, optical volume is only partially correlated with hemoglobin content, suggesting that changes in other dry mass components such as parasite mass may also be assessed using this technique. The unique ability of QPS to discriminate individual healthy and infected cells using spectroscopic changes indicates that the approach can be used to detect disease. PMID:27087557

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

    PubMed

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

    1996-03-01

    Early prediction of outcome after global hypoxia of the brain requires accurate determination of the nature and extent of neurological injury and is cardinal for patient management. Cerebral metabolites of gray and white matter were determined sequentially after near-drowning using quantitative 1H nuclear magnetic resonance spectroscopy (MRS) in 16 children. Significant metabolite abnormalities were demonstrated in all patients compared with their age-matched normal controls. Severity of brain damage was quantified from metabolite concentrations and ratios. Loss of N-acetylaspartate, a putative neuronal marker, from gray matter preceded that observed in white matter and was more severe. Total creatine decreased, while lactate and glutamine/glutamate concentrations increased. Changes progressed with time after injury. A spectroscopic prognosis index distinguished between good outcome (n = 5) and poor outcome (n = 11) with one false negative (bad outcome after borderline MRS result) and no false positive results (100% specificity). The distinction was made with 90% sensitivity early (after 48 h) and became 100% later (by days 3 and 4). This compared with 50-75% specificity and 70-100% sensitivity based upon single clinical criteria. MRS performed sequentially in occipital gray matter provides useful objective information which can significantly enhance the ability to establish prognosis after near-drowning. PMID:8636425

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

    NASA Astrophysics Data System (ADS)

    Fan, Yuxia; Cheng, Fang; Xie, Lijuan

    2010-04-01

    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.

  2. Evaluation of green coffee beans quality using near infrared spectroscopy: a quantitative approach.

    PubMed

    Santos, João Rodrigo; Sarraguça, Mafalda C; Rangel, António O S S; Lopes, João A

    2012-12-01

    Characterisation of coffee quality based on bean quality assessment is associated with the relative amount of defective beans among non-defective beans. It is therefore important to develop a methodology capable of identifying the presence of defective beans that enables a fast assessment of coffee grade and that can become an analytical tool to standardise coffee quality. In this work, a methodology for quality assessment of green coffee based on near infrared spectroscopy (NIRS) is proposed. NIRS is a green chemistry, low cost, fast response technique without the need of sample processing. The applicability of NIRS was evaluated for Arabica and Robusta varieties from different geographical locations. Partial least squares regression was used to relate the NIR spectrum to the mass fraction of defective and non-defective beans. Relative errors around 5% show that NIRS can be a valuable analytical tool to be used by coffee roasters, enabling a simple and quantitative evaluation of green coffee quality in a fast way. PMID:22953929

  3. Quantitative estimation of concentrations of dissolved rare earth elements using reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Dai, Jingjing; Wang, Denghong; Wang, Runsheng; Chen, Zhenghui

    2013-01-01

    Characteristic spectral parameters such as the wavelength and depth of absorption bands are widely used to quantitatively estimate the composition of samples from hyperspectral reflectance data in soil science, mineralogy as well as vegetation study. However, little research has been conducted on the spectral characteristic of rare earth elements (REE) and their relationship with chemical composition of aqueous solutions. Reflectance spectra of ore leachate solutions and contaminated stream water from a few REE mines in the Jiangxi Province, China, are studied for the first time in this work. The results demonstrate that the six diagnostic absorption features of the rare earths are recognized in visible and near-infrared wavelengths at 574, 790, 736, 520, 861, and 443 nm. The intensity of each of these six absorption bands is linearly correlated with the abundance of total REE, with the r2 value >0.95 and the detection limit at ≥75,000 μg/L. It is suggested that reflectance spectroscopy provides an ideal routine analytical tool for characterizing leachate samples. The outcome of this study also has implications for monitoring the environmental effect of REE mining, in particular in stream water systems by hyperspectral remote sensing.

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

  6. Quantitative monitoring of membrane permeation via in-situ ATR FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Beckingham, Bryan; Miller, Daniel

    Ion conducting membranes are of interest for various energy applications including fuel cells and artificial photosynthesis systems. Within the context of artificial photosynthesis, membranes are desired that facilitate the ion transport necessary to feed the electrochemical reactions while meeting various additional selectivity and permeability demands depending on the CO2 reduction products. Herein, we demonstrate the use of in-situ ATR FT-IR spectroscopy to quantitatively resolve the concentration of single and multicomponent mixtures of various CO2 reduction products including methanol, formate and acetate. We then apply this methodology to the in-situ monitoring of the permeation of single and multicomponent mixtures across commercially available membranes. Membrane permeabilities and selectivities calculated from the single component time-resolved concentration curves are compared to the multicomponent permeation experiments. This material is based upon work performed at the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC000493.

  7. Hemoglobin consumption by P. falciparum in individual erythrocytes imaged via quantitative phase spectroscopy

    NASA Astrophysics Data System (ADS)

    Rinehart, Matthew T.; Park, Han Sang; Walzer, Katelyn A.; Chi, Jen-Tsan Ashley; Wax, Adam

    2016-04-01

    Plasmodium falciparum infection causes structural and biochemical changes in red blood cells (RBCs). To quantify these changes, we apply a novel optical technique, quantitative phase spectroscopy (QPS) to characterize individual red blood cells (RBCs) during the intraerythrocytic life cycle of P. falciparum. QPS captures hyperspectral holograms of individual RBCs to measure spectroscopic changes across the visible wavelength range (475–700 nm), providing complex information, i.e. amplitude and phase, about the light field which has interacted with the cell. The complex field provides complimentary information on hemoglobin content and cell mass, which are both found to dramatically change upon infection by P. falciparum. Hb content progressively decreases with parasite life cycle, with an average 72.2% reduction observed for RBCs infected by schizont-stage P. falciparum compared to uninfected cells. Infection also resulted in a 33.1% reduction in RBC’s optical volume, a measure of the cells’ non-aqueous components. Notably, optical volume is only partially correlated with hemoglobin content, suggesting that changes in other dry mass components such as parasite mass may also be assessed using this technique. The unique ability of QPS to discriminate individual healthy and infected cells using spectroscopic changes indicates that the approach can be used to detect disease.

  8. Quantitative Kα line spectroscopy for energy transport in ultra-intense laser plasma interaction

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Nishimura, H.; Fujioka, S.; Arikawa, Y.; Nakai, M.; Chen, H.; Park, J.; Williams, G. J.; Ozaki, T.; Shiraga, H.; Kojima, S.; Johzaki, T.; Sunahara, A.; Miyanaga, N.; Kawanaka, J.; Nakata, Y.; Jitsuno, T.; Azechi, H.

    2016-03-01

    Absolute Ka line spectroscopy is proposed for studying laser-plasma interactions taking place in the cone-guided fast ignition targets. X-ray spectra ranging from 20 to 100 keV were quantitatively measured with a Laue spectrometer. The absolute sensitivities of the Laue spectrometer system were calibrated using pre-characterized laser-produced x-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for x-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency, is derived as a consequence of this work. The absolute yield of Au and Ta Ka lines were measured in the fast ignition experimental campaign performed at Institute of Laser Engineering, Osaka University. Applying the hot electron spectrum information from the electron spectrometer, an energy transfer efficiency of the incident LFEX [1], a kJ-class PW laser, to hot electrons was derived for a planar and cone-guided geometry.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    PubMed Central

    Chung, SH; Cerussi, AE; Merritt, SI; Ruth, J; Tromberg, BJ

    2012-01-01

    We describe the development of a non-invasive method for quantitative tissue temperature measurements using Broadband diffuse optical spectroscopy (DOS). Our approach is based on well-characterized opposing shifts in near-infrared (NIR) water absorption spectra that appear with temperature and macromolecular binding state. Unlike conventional reflectance methods, DOS is used to generate scattering-corrected tissue water absorption spectra. This allows us to separate the macromolecular bound water contribution from the thermally induced spectral shift using the temperature isosbestic point at 996 nm. The method was validated in intralipid tissue phantoms by correlating DOS with thermistor measurements (R = 0.96) with a difference of 1.1 ± 0.91 °C over a range of 28–48 °C. Once validated, thermal and hemodynamic (i.e. oxy- and deoxy-hemoglobin concentration) changes were measured simultaneously and continuously in human subjects (forearm) during mild cold stress. DOS-measured arm temperatures were consistent with previously reported invasive deep tissue temperature studies. These results suggest that DOS can be used for non-invasive, co-registered measurements of absolute temperature and hemoglobin parameters in thick tissues, a potentially important approach for optimizing thermal diagnostics and therapeutics. PMID:20551502

  11. Hemoglobin consumption by P. falciparum in individual erythrocytes imaged via quantitative phase spectroscopy.

    PubMed

    Rinehart, Matthew T; Park, Han Sang; Walzer, Katelyn A; Chi, Jen-Tsan Ashley; Wax, Adam

    2016-01-01

    Plasmodium falciparum infection causes structural and biochemical changes in red blood cells (RBCs). To quantify these changes, we apply a novel optical technique, quantitative phase spectroscopy (QPS) to characterize individual red blood cells (RBCs) during the intraerythrocytic life cycle of P. falciparum. QPS captures hyperspectral holograms of individual RBCs to measure spectroscopic changes across the visible wavelength range (475-700 nm), providing complex information, i.e. amplitude and phase, about the light field which has interacted with the cell. The complex field provides complimentary information on hemoglobin content and cell mass, which are both found to dramatically change upon infection by P. falciparum. Hb content progressively decreases with parasite life cycle, with an average 72.2% reduction observed for RBCs infected by schizont-stage P. falciparum compared to uninfected cells. Infection also resulted in a 33.1% reduction in RBC's optical volume, a measure of the cells' non-aqueous components. Notably, optical volume is only partially correlated with hemoglobin content, suggesting that changes in other dry mass components such as parasite mass may also be assessed using this technique. The unique ability of QPS to discriminate individual healthy and infected cells using spectroscopic changes indicates that the approach can be used to detect disease. PMID:27087557

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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 3 g/100 g. Classes of components - aromatic anhydrides and alcohols - used in alkyd resin synthesis were also successfully quantified, with standard uncertainties in the range of 2-3 g/100 g. 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.

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

    PubMed

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

    2013-11-01

    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

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

    SciTech Connect

    Robert P. Lucht

    2005-03-09

    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.

  17. [Quantitative analysis of hybrid maize seed purity using near infrared spectroscopy].

    PubMed

    Huang, Yan-Yan; Zhu, Li-Wei; Ma, Han-Xu; Li, Jun-Hui; Sun, Bao-Qi; Sun, Qun

    2011-10-01

    A quantitative identification model for testing the purity of hybrid maize seeds was built by near infrared reflectance spectroscopy with quantitative partial least squares (QPLS). The NIR spectra of 123 seeds powder samples (Nongda108 and mother178) with the purity of 600-100% were collected using MPA spectrometer. All samples were divided into two groups: calibration set (82 samples) and validation set (41 samples). Synergy interval partial least squares (SiPLSu) was used for selecting effective spectral regions and building models. The influences of different spectral regions and different calibration samples on the prediction results and different main components were compared. The result showed that the spectral regions 6 000 8 000, 6 000-9 000 and 6 000-10 000 cm(-1) all had better prediction results (R2 over 95%). Spectral region 6 000-10 000 cm(-1) was regarded the optimum spectral region for building the model with less main components(8), and the determination coefficient (R2) of calibration and validation sets were 96.61% and 97.67% respectively, SEC (standard error of calibration) and SEP (standard error of prediction) were 2.15% and 1.78% respectively, RSDs (relative standard deviation) were 2.04% and 1.94% respectively. Even with different calibration samples, the average determination coefficients (R2) of calibration and validation sets were 96.21% and 95.75%, SEC (standard error of calibration) and SEP (standard error of prediction) were 2.29% and 2.23% respectively, RSDs (relative standard deviation) were 2.81% and 2.73% respectively, which further proved the model's stability. With the increase in the number of main components, the identification rates in calibration set and validation set gradually increased, when the number of main components reached 8, the model determination coefficients reached the best (96.61% and 97.67%), and related coefficients of true value and predicted value were 98.29% and 98.87% respectively. The results have important value for rapid and accurate testing of hybrid maize seed purity. PMID:22250540

  18. Infrared Spectroscopy as a Versatile Analytical Tool for the Quantitative Determination of Antioxidants in Agricultural Products, Foods and Plants

    PubMed Central

    Cozzolino, Daniel

    2015-01-01

    Spectroscopic methods provide with very useful qualitative and quantitative information about the biochemistry and chemistry of antioxidants. Near infrared (NIR) and mid infrared (MIR) spectroscopy are considered as powerful, fast, accurate and non-destructive analytical tools that can be considered as a replacement of traditional chemical analysis. In recent years, several reports can be found in the literature demonstrating the usefulness of these methods in the analysis of antioxidants in different organic matrices. This article reviews recent applications of infrared (NIR and MIR) spectroscopy in the analysis of antioxidant compounds in a wide range of samples such as agricultural products, foods and plants. PMID:26783838

  19. Quantitative treatment of coarsely binned low-resolution recordings in molecular absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Spietz, Peter; Martn, Juan Carlos Gmez; Burrows, John P.

    2006-06-01

    Optical multichannel detectors like photodiode arrays or CCD cameras combined with grating spectrometers are commonly used as detection systems in quantitative absorption spectroscopy. As a trade-off to broad spectral coverage, banded spectral features are sometimes recorded with insufficient spectral resolution and/or insufficiently fine detector binning. This renders the true physical spectrum of recorded intensities changed by instrumental and spectrum specific artefacts thus impeding comparability between results from different set-ups. In this work, it is demonstrated that in the case of a "well-behaved" - i.e. free of ro-vibronic structure - absorption band like the iodine monoxide IO(4 ? 0) transition, these effects can easily change the apparent peak absorption by up to 50%. Also deviations from the strict linearity (Beer-Lambert's law) between absorber concentration and apparent, i.e. pixelwise optical density occur. This can be critical in studies of chemical kinetics. It is shown that the observed non-linearity can cause errors of up to 50% in the determination of a second order rate coefficient for the IO self reaction. To overcome the problem, a consistent and rigorous integral approach for the treatment of intensity recordings is developed. Linearity between optical density and absorber concentration thereby is re-established. The method is validated using artificial test data as well as experimental data of the IO(4 ? 0) absorption transition, obtained in the context of I 2/O 3 photochemistry studies. The agreement is accurate to within 2% (test data) and 3% (experimental data) supporting the validity of the approach. Possible consequences for other spectroscopic work are indicated.

  20. Quantitative treatment of coarsely binned low-resolution recordings in molecular absorption spectroscopy.

    PubMed

    Spietz, Peter; Martín, Juan Carlos Gómez; Burrows, John P

    2006-06-01

    Optical multichannel detectors like photodiode arrays or CCD cameras combined with grating spectrometers are commonly used as detection systems in quantitative absorption spectroscopy. As a trade-off to broad spectral coverage, banded spectral features are sometimes recorded with insufficient spectral resolution and/or insufficiently fine detector binning. This renders the true physical spectrum of recorded intensities changed by instrumental and spectrum specific artefacts thus impeding comparability between results from different set-ups. In this work, it is demonstrated that in the case of a "well-behaved"--i.e. free of ro-vibronic structure--absorption band like the iodine monoxide IO(4<--0) transition, these effects can easily change the apparent peak absorption by up to 50%. Also deviations from the strict linearity (Beer-Lambert's law) between absorber concentration and apparent, i.e. pixelwise optical density occur. This can be critical in studies of chemical kinetics. It is shown that the observed non-linearity can cause errors of up to 50% in the determination of a second order rate coefficient for the IO self reaction. To overcome the problem, a consistent and rigorous integral approach for the treatment of intensity recordings is developed. Linearity between optical density and absorber concentration thereby is re-established. The method is validated using artificial test data as well as experimental data of the IO(4<--0) absorption transition, obtained in the context of I2/O3 photochemistry studies. The agreement is accurate to within +/-2% (test data) and +/-3% (experimental data) supporting the validity of the approach. Possible consequences for other spectroscopic work are indicated. PMID:16387540

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

    NASA Astrophysics Data System (ADS)

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

    2005-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  3. Quantitative Macro-Raman Spectroscopy on Microparticle-Based Pharmaceutical Dosage Forms.

    PubMed

    Wang, Hui; Williams, Lisa; Hoe, Susan; Lechuga-Ballesteros, David; Vehring, Reinhard

    2015-07-01

    Quantitative macro-Raman spectroscopy was applied to the analysis of the bulk composition of pharmaceutical drug powders. Powders were extracted from seven commercial lactose-carrier-based dry-powder inhalers: Flixotide 50, 100, 250, and 500 μg/dose (four concentrations of fluticasone propionate) and Seretide 100, 250, and 500 μg/dose (three concentrations of fluticasone propionate, each with 50 μg/dose salmeterol xinafoate ). Also, a carrier-free pressurized metered-dose inhaler of the same combination product, Seretide 50 (50 μg fluticasone propionate and 25 μg salmeterol xinafoate per dose) was tested. The applicability of a custom-designed dispersive macro-Raman instrument with a large sample volume of 0.16 μL was tested to determine the composition of the multicomponent powder samples. To quantify the error caused by sample heterogeneity, a Monte Carlo model was developed to predict the minimum sample volume required for representative sampling of potentially heterogeneous samples at the microscopic level, characterized by different particle-size distributions and compositions. Typical carrier-free respirable powder samples required a minimum sample volume on the order of 10(-4) μL to achieve representative sampling with less than 3% relative error. In contrast, dosage forms containing non-respirable carriers (e.g., lactose) required a sample volume on the order of 0.1 μL for representative measurements. Error analysis of the experimental results showed good agreement with the error predicted by the simulation. PMID:26037516

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  5. Quantitative interpretation of molecular dynamics simulations for X-ray photoelectron spectroscopy of aqueous solutions

    NASA Astrophysics Data System (ADS)

    Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.; Brown, Matthew A.

    2016-04-01

    Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy (XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyte interface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquid interface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer description of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (<300 eV) where the ad hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquid interfaces are discussed.

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

    NASA Astrophysics Data System (ADS)

    Robles, Francisco E.

    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.

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

    PubMed

    Cahoon, Erica M; Almirall, Jose R

    2012-03-01

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

  8. [Near infrared spectroscopy quantitative analysis model based on incremental neural network with partial least squares].

    PubMed

    Cao, Hui; Li, Da-Hang; Liu, Ling; Zhou, Yan

    2014-10-01

    This paper proposes an near infrared spectroscopy quantitative analysis model based on incremental neural network with partial least squares. The proposed model adopts the typical three-layer back-propagation neural network (BPNN), and the absorbance of different wavelengths and the component concentration are the inputs and the outputs, respectively. Partial least square (PLS) regression is performed on the history training samples firstly, and the obtained history loading matrices of the in- dependent variables and the dependent variables are used for determining the initial weights of the input layer and the output lay- er, respectively. The number of the hidden layer nodes is set as the number of the principal components of the independent varia- bles. After a set of new training samples is collected, PLS regression is performed on the combination dataset consisting of the new samples and the history loading matrices to calculate the new loading matrices. The history loading matrices and the new loading matrices are fused to obtain the new initial weights of the input layer and the output layer of the proposed model. Then the new samples are used for training the proposed mode to realize the incremental update. The proposed model is compared with PLS, BPNN, the BPNN based on PLS (PLS-BPNN) and the recursive PLS (RPLS) by using the spectra data of flue gas of nat- ural gas combustion. For the concentration prediction of the carbon dioxide in the flue gas, the root mean square error of predic- tion (RMSEP) of the proposed model are reduced by 27.27%, 58.12%, 19.24% and 14.26% than those of PLS, BPNN, PLS- BPNN and RPLS, respectively. For the concentration prediction of the carbon monoxide in the flue gas, the RMSEP of the pro- posed model are reduced by 20.65%, 24.69%, 18.54% and 19.42% than those of PLS, BPNN, PLS-BPNN and RPLS, re- spectively. For the concentration prediction of the methane in the flue gas, the RMSEP of the proposed model are reduced by 27.56%, 37.76%, 8.63% and 3.20% than those of PLS, BPNN, PLS-BPNN and RPLS, respectively. Experiments results show that the proposed model could optimize the construction and the initial weights of BPNN by PLS and has higher prediction effectiveness. Moreover, based on the information of the built model, the proposed model uses the new samples for incremental update without accessing the history samples. Hence, the proposed model has better robustness and generalization. PMID:25739228

  9. Near- and Mid-Infrared Reflectance Spectroscopy for the Quantitative and Qualitative Analysis of Agricultural Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For several decades near-infrared diffuse reflectance spectroscopy (NIRS) has been used to determine the composition of a variety of agricultural products. More recently, diffuse reflectance Fourier transform mid-infrared spectroscopy (DRIFTS) has similarly been shown to be able to determine the co...

  10. Application of terahertz time-domain spectroscopy combined with chemometrics to quantitative analysis of imidacloprid in rice samples

    NASA Astrophysics Data System (ADS)

    Chen, Zewei; Zhang, Zhuoyong; Zhu, Ruohua; Xiang, Yuhong; Yang, Yuping; Harrington, Peter B.

    2015-12-01

    Terahertz time-domain spectroscopy (THz-TDS) has been utilized as an effective tool for quantitative analysis of imidacloprid in rice powder samples. Unlike previous studies, our method for sample preparation was mixing imidacloprid with rice powder instead of polyethylene. Then, terahertz time domain transmission spectra of these mixed samples were measured and the absorption coefficient spectra of the samples with frequency range extending from 0.3 to 1.7 THz were obtained. Asymmetric least square (AsLS) method was utilized to correct the slope baselines that are presented in THz absorption coefficient spectra and improve signal-to-noise ratio of THz spectra. Chemometrics methods, including partial least squares (PLS), support vector regression (SVR), interval partial least squares (iPLS), and backward interval partial least squares (biPLS), were used for quantitative model building and prediction. To achieve a reliable and unbiased estimation, bootstrapped Latin partition was chosen as an approach for statistical cross-validation. Results showed that the mean value of root mean square error of prediction (RMSEP) for PLS (0.5%) is smaller than SVR (0.7%), these two methods were based on the whole absorption coefficient spectra. In addition, PLS performed a better performance with a lower RMSEP (0.3%) based on the THz absorption coefficient spectra after AsLS baseline correction. Alternatively, two methods for variable selection, namely iPLS and biPLS, yielded models with improved predictions. Comparing with conventional PLS and SVR, the mean values of RMSEP were 0.4% (iPLS) and 0.3% (biPLS) by selecting the informative frequency ranges. The results demonstrated that an accurate quantitative analysis of imidacloprid in rice powder samples could be achieved by terahertz time-domain transmission spectroscopy combined with chemometrics. Furthermore, these results demonstrate that THz time-domain spectroscopy can be used for quantitative determinations of other pesticides in other agricultural products.

  11. Synthesis, spectral (FT-IR, UV-visible, NMR) features, biological activity prediction and theoretical studies of 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione and its tautomer

    NASA Astrophysics Data System (ADS)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj; Manjula, P. S.; Sarojini, B. K.; Narayana, B.

    2016-03-01

    Triazole compounds constitute an important class of organic chemistry due to their various biological and corrosion inhibition activities. The synthesis scheme of a new triazole compound namely, 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione (4AHT) has been theoretically analyzed. Our density functional theory (DFT) based calculations show that the synthesis of 4AHT is energetically feasible at the room temperature as the reaction is exothermic, spontaneous as well as favored in forward direction. The calculated bond-lengths are found to be in good agreement with corresponding crystallographic values. We have considered two possible tautomers of 4AHT viz. thione and thiol forms. The FT-IR (KBr disc), UV-visible (ethanol) and 1H-NMR (DMSO) spectra of 4AHT have been recorded. The vibrational modes have been assigned on the basis of their potential energy distributions and scaled wavenumbers agree well with the FT-IR wavenumbers. Time dependent DFT calculations are performed to analyze the electronic transitions for various excited states which reproduce the experimental peak observed in UV-visible spectrum. Using gauge independent atomic orbital method 1H-NMR chemical shifts have been calculated and correlated with the experimental chemical shifts with the linear correlation coefficient of 0.9453. Our spectral analyses reveal the dominance of thione over thiol form of 4AHT. The chemical reactivity of 4AHT has been discussed by molecular electrostatic potential surface as well as various electronic parameters. The biological activities of 4AHT have also been explored theoretically and it has been found that the title molecule can act as a potential inhibitor of cyclin-dependent kinase 5 enzyme. These findings may guide the synthesis and design of new triazole compounds with interesting biological activity.

  12. A quantitative study for determination of sugar concentration using attenuated total reflectance terahertz (ATR-THz) spectroscopy

    NASA Astrophysics Data System (ADS)

    Suhandy, Diding; Suzuki, Tetsuhito; Ogawa, Yuichi; Kondo, Naoshi; Ishihara, Takeshi; Takemoto, Yuichiro

    2011-06-01

    The objective of our research was to use ATR-THz spectroscopy together with chemometric for quantitative study in food analysis. Glucose, fructose and sucrose are main component of sugar both in fresh and processed fruits. The use of spectroscopic-based method for sugar determination is well reported especially using visible, near infrared (NIR) and middle infrared (MIR) spectroscopy. However, the use of terahertz spectroscopy for sugar determination in fruits has not yet been reported. In this work, a quantitative study for sugars determination using attenuated total reflectance terahertz (ATR-THz) spectroscopy was conducted. Each samples of glucose, fructose and sucrose solution with different concentrations were prepared respectively and their absorbance spectra between wavenumber 20 and 450 cm-1 (between 0.6 THz and 13.5 THz) were acquired using a terahertz-based Fourier Transform spectrometer (FARIS-1S, JASCO Co., Japan). This spectrometer was equipped with a high pressure of mercury lamp as light source and a pyroelectric sensor made from deuterated L-alanine triglycine sulfate (DLTGS) as detector. Each spectrum was acquired using 16 cm-1 of resolution and 200 scans for averaging. The spectra of water and sugar solutions were compared and discussed. The results showed that increasing sugar concentration caused decreasing absorbance. The correlation between sugar concentration and its spectra was investigated using multivariate analysis. Calibration models for glucose, fructose and sucrose determination were developed using partial least squares (PLS) regression. The calibration model was evaluated using some parameters such as coefficient of determination (R2), standard error of calibration (SEC), standard error of prediction (SEP), bias between actual and predicted sugar concentration value and ratio prediction to deviation (RPD) parameter. The cross validation method was used to validate each calibration model. It is showed that the use of ATR-THz spectroscopy combined with appropriate chemometric can be a potential for a rapid determination of sugar concentrations.

  13. Quantitative optical spectroscopy: A robust tool for direct measurement of breast cancer vascular oxygenation and total hemoglobin content in vivo

    PubMed Central

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

    2009-01-01

    We propose the use of a robust, biopsy-needle based, fiber-optic tool for routine clinical quantification of tumor oxygenation at the time of diagnostic biopsy for breast cancer. The purpose of this study was to demonstrate diffuse reflectance spectroscopy as a quantitative tool to measure oxygenation levels in the vascular compartment of breast cancers in vivo via an optical biopsy technique. Thirty-five patients undergoing surgical treatment for breast cancer were recruited for the study at Duke University Medical Center. Diffuse reflectance spectroscopy was performed on the tumors in situ before surgical resection, followed by needle-core biopsy of the optically-measured tissue. Hemoglobin saturation and total hemoglobin content were quantified from 76 optical spectra-tissue biopsy pairs, consisting of 20 malignant, 23 benign, and 33 adipose tissues. Hemoglobin saturation in malignant tissues was significantly lower than non-malignant tissues (p < 0.002), and was negatively correlated with tumor size and pathologic tumor category (pT) (p < 0.05). Hemoglobin saturation was positively correlated with total hemoglobin content in malignant tissues (p < 0.02). HER2/neu amplified tumors exhibited significantly higher total hemoglobin content (p < 0.05) and significantly higher hemoglobin saturation (p < 0.02), which is consistent with a model of increased angiogenesis and tumor perfusion promoted by HER2/neu amplification. Diffuse reflectance spectroscopy could aid in prognosis and prediction in breast cancer via quantitative assessment of tumor physiology at the time of diagnostic biopsy. PMID:19293184

  14. Quantitative femtosecond charge transfer dynamics at organic/electrode interfaces studied by core-hole clock spectroscopy.

    PubMed

    Cao, Liang; Gao, Xing-Yu; Wee, Andrew T S; Qi, Dong-Chen

    2014-12-10

    Organic semiconductor materials have important applications in organic electronics and other novel hybrid devices. In these devices, the transport of charge carriers across the interfaces between organic molecules and electrodes plays an important role in determining the device performance. Charge transfer dynamics at the organic/electrode interface usually occurs at the several femtoseconds timescale, and quantitative charge transfer dynamics data can been inferred using synchrotron-based core-hole clock (CHC) spectroscopy. In this research news, we have reviewed recent progress in the applications of CHC spectroscopy on the quantitative characterization of charge transfer dynamics at organic/electrode interfaces. By examining charge transfer dynamics at different types of interface, from weakly interacting van der Waals-type interfaces to interfaces with strong covalent bonds, we discuss a few factors that have been found to affect the charge transfer dynamics. We also review the application of CHC spectroscopy to quantify through-bonds and through-space charge transport in organic molecules. PMID:24692009

  15. [Quantitative Analysis of Copper Impurity in Silver Jewellery by Laser-Ablation Laser-Induced Breakdown Spectroscopy].

    PubMed

    Chen, Yu-qi; Mo, Jun-yu; Zhou, Qi; Lou, Yang; Li, Run-hua

    2015-03-01

    High spectral analysis sensitivity can be achieved with orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy under minimal sample ablation. Therefore, the contradiction between spatial resolution and analytical sensitivity existed in single-pulse laser-induced breakdown spectroscopy can be resolved fundamentally in this technique. In order to eliminate the influence of different experimental parameters to the signal intensities and final results of quantitative analysis, the correlation between copper atomic emission and silver atomic emission was studied experimentally in this technique for silver jewellery samples. It was demonstrated that the intensity of atomic emission of copper at 324.75 nm and that of silver at 328.07 nm was linearly correlated with high correlation coefficient. Therefore, it was possible to eliminate the influence of different experimental parameters, such as geometrical arrangement and pulse energy of the ablation laser to the signal of copper atomic emission by selecting 328.07 nm line of silver as internal standard. A quantitative analysis of copper impurity in silver jewellery can be realized by using orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy. A calibration curve of copper was successfully built based on internal standard method while selecting 328.07 nm line of silver as internal standard. The limit of detection of copper in silver matrix was determined to be 44 ppm in this technique when the crater's diameter was about 17 μm under current experimental condition. PMID:26117897

  16. Quantitative Raman Spectroscopy to monitor microbial metabolism in situ under pressure

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  18. Quantitative Analysis of Carbon Steel with Multi-Line Internal Standard Calibration Method Using Laser-Induced Breakdown Spectroscopy.

    PubMed

    Pan, Congyuan; Du, Xuewei; An, Ning; Zeng, Qiang; Wang, Shengbo; Wang, Qiuping

    2016-04-01

    A multi-line internal standard calibration method is proposed for the quantitative analysis of carbon steel using laser-induced breakdown spectroscopy (LIBS). A procedure based on the method was adopted to select the best calibration curves and the corresponding emission lines pairs automatically. Laser-induced breakdown spectroscopy experiments with carbon steel samples were performed, and C, Cr, and Mn were analyzed via the proposed method. Calibration curves of these elements were constructed via a traditional single line internal standard calibration method and a multi-line internal standard calibration method. The calibration curves obtained were evaluated with the determination coefficient, the root mean square error of cross-validation, and the average relative error of cross-validation. All of the parameters were improved significantly with the proposed method. The results show that accurate and stable calibration curves can be obtained efficiently via the multi-line internal standard calibration method. PMID:26872822

  19. Quantitative Determination of Methylcyclohexanone Mixtures Using 13C NMR Spectroscopy: A Project for an Advanced Chemistry Laboratory

    NASA Astrophysics Data System (ADS)

    Lefevre, Joseph W.; Silveira, Augustine, Jr.

    2000-01-01

    The percentage composition of mixtures of four methylcyclohexanones was determined using 13C NMR spectroscopy as a quantitative analytical method. The data were acquired using standard broadband proton decoupling and inverse-gated decoupling, the latter done both with and without the paramagnetic relaxation reagent chromium(III) acetylacetonate [Cr(acac)3]. The standard broadband decoupled spectrum resulted in percentages far from the actual values owing to the varying nuclear Overhauser enhancements (NOEs) and spin-lattice relaxation times (T1's) of the various carbon atoms. These effects were eliminated in the inverse-gated experiments, and the results were very close to the actual percentages. Before examining the mixtures, the students studied a pure sample of 2-methylcyclohexanone. They assigned the 13C spectrum and determined the T1 of the carbonyl group both with and without Cr(acac)3 using the inversion-recovery method. Then a five-times-T1 delay was inserted between pulses in all subsequent inverse-gated decoupling experiments. This project provides students with valuable experience with modern NMR techniques. These include COrrelated SpectroscopY (COSY), Distortionless Enhancement by Polarization Transfer (DEPT) spectroscopy, HETeronuclear CORrelated (HETCOR) spectroscopy, T1 determination, standard broadband versus inverse-gated decoupling, and the addition of a paramagnetic relaxation reagent to dramatically shorten both the T

  20. Structures of glycans bound to receptors from saturation transfer difference (STD) NMR spectroscopy: quantitative analysis by using CORCEMA-ST.

    PubMed

    Enríquez-Navas, Pedro M; Guzzi, Cinzia; Muñoz-García, Juan C; Nieto, Pedro M; Angulo, Jesús

    2015-01-01

    Glycan-receptor interactions are of fundamental relevance for a large number of biological processes, and their kinetics properties (medium/weak binding affinities) make them appropriated to be studied by ligand observed NMR techniques, among which saturation transfer difference (STD) NMR spectroscopy has been shown to be a very robust and powerful approach. The quantitative analysis of the results from a STD NMR study of a glycan-receptor interaction is essential to be able to translate the resulting spectral intensities into a 3D molecular model of the complex. This chapter describes how to carry out such a quantitative analysis by means of the Complete Relaxation and Conformational Exchange Matrix Approach for STD NMR (CORCEMA-ST), in general terms, and an example of a previous work on an antibody-glycan interaction is also shown. PMID:25753726

  1. Quantitative spectroscopy of hot stars: accurate atomic data applied on a large scale as driver of recent breakthroughs

    NASA Astrophysics Data System (ADS)

    Przybilla, Norbert; Schaffenroth, Veronika; Nieva, Maria-Fernanda

    2015-08-01

    OB-type stars present hotbeds for non-LTE physics because of their strong radiation fields that drive the atmospheric plasma out of local thermodynamic equilibrium. We report on recent breakthroughs in the quantitative analysis of the optical and UV-spectra of OB-type stars that were facilitated by application of accurate and precise atomic data on a large scale. An astophysicist's dream has come true, by bringing observed and model spectra into close match over wide parts of the observed wavelength ranges. This facilitates tight observational constraints to be derived from OB-type stars for wide applications in astrophysics. However, despite the progress made, many details of the modelling may be improved further. We discuss atomic data needs in terms of laboratory measurements and also ab-initio calculations. Particular emphasis is given to quantitative spectroscopy in the near-IR, which will be in focus in the era of the upcoming extremely large telescopes.

  2. Color change of tourmaline by heat treatment and electron beam irradiation: UV-Visible, EPR, and Mid-IR spectroscopic analyses

    NASA Astrophysics Data System (ADS)

    Maneewong, Apichate; Seong, Baek Seok; Shin, Eun Joo; Kim, Jeong Seog; Kajornrith, Varavuth

    2016-01-01

    The color of pink tourmaline gemstone changed to colorless when heating at temperature of 600 °C in air. This colorless tourmaline recovered its pink color when irradiated with an electron beam (e-beam) of 800 kGy. The origin of the color change was investigated in three types of tourmaline gemstones, two pink are from Afghanistan and one green are from Nigeria, by using Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and Energy Dispersive X-ray Fluorescence (EDXRF). The UV-Vis absorption spectrum of the pink tourmaline with higher Mn concentration (T2, 0.24 wt%) showed characteristic absorption peaks originating from the Mn3+ color center: two absorption bands centered at wavelength of 396 and 520 nm, respectively. Both absorption bands disappeared when heated in air at 600 °C and then reappeared when irradiated with an e-beam at 800 kGy. EPR T2 spectra showed that the color change was related to the valence change of Mn3+ to Mn2+ and vice versa. The pink tourmaline of lower MnO content (T1, 0.08 wt%) also became colorless when heated, but the color was not recovered when the gemstone underwent e-beam irradiation. Instead, a yellow color was obtained. UV-Vis and FTIR spectra indicated that this yellow color originated from a decomposition of the hydroxyl group (-OH) into O- and Ho by the e-beam irradiation. Green tourmaline did not show any color change with either heat treatment or e-beam irradiation.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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 γ = 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.

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

    PubMed

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

    2015-01-01

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

  5. Towards quantitative laser-induced breakdown spectroscopy analysis of soil samples

    NASA Astrophysics Data System (ADS)

    Bousquet, B.; Sirven, J.-B.; Canioni, L.

    2007-12-01

    A quantitative analysis of chromium in soil samples is presented. Different emission lines related to chromium are studied in order to select the best one for quantitative features. Important matrix effects are demonstrated from one soil to the other, preventing any prediction of concentration in different soils on the basis of a univariate calibration curve. Finally, a classification of the LIBS data based on a series of Principal Component Analyses (PCA) is applied to a reduced dataset of selected spectral lines related to the major chemical elements in the soils. LIBS data of heterogeneous soils appear to be widely dispersed, which leads to a reconsideration of the sampling step in the analysis process.

  6. 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...

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  8. Rapid Quantitative Determination of Squalene in Shark Liver Oils by Raman and IR Spectroscopy.

    PubMed

    Hall, David W; Marshall, Susan N; Gordon, Keith C; Killeen, Daniel P

    2016-01-01

    Squalene is sourced predominantly from shark liver oils and to a lesser extent from plants such as olives. It is used for the production of surfactants, dyes, sunscreen, and cosmetics. The economic value of shark liver oil is directly related to the squalene content, which in turn is highly variable and species-dependent. Presented here is a validated gas chromatography-mass spectrometry analysis method for the quantitation of squalene in shark liver oils, with an accuracy of 99.0 %, precision of 0.23 % (standard deviation), and linearity of >0.999. The method has been used to measure the squalene concentration of 16 commercial shark liver oils. These reference squalene concentrations were related to infrared (IR) and Raman spectra of the same oils using partial least squares regression. The resultant models were suitable for the rapid quantitation of squalene in shark liver oils, with cross-validation r (2) values of >0.98 and root mean square errors of validation of ≤4.3 % w/w. Independent test set validation of these models found mean absolute deviations of the 4.9 and 1.0 % w/w for the IR and Raman models, respectively. Both techniques were more accurate than results obtained by an industrial refractive index analysis method, which is used for rapid, cheap quantitation of squalene in shark liver oils. In particular, the Raman partial least squares regression was suited to quantitative squalene analysis. The intense and highly characteristic Raman bands of squalene made quantitative analysis possible irrespective of the lipid matrix. PMID:26620374

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

    SciTech Connect

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

    1999-12-10

    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.

  10. Utilization of O4 slant column density to derive aerosol layer height from a space-borne UV-visible hyperspectral sensor: sensitivity and case study

    NASA Astrophysics Data System (ADS)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-02-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 1040 molecules2 cm-5, to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nm, the O4 absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 m for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 % of retrieved aerosol effective heights are within the error range of 1 km compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    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.

  13. [Study on the application of ridge regression to near-infrared spectroscopy quantitative analysis and optimum wavelength selection].

    PubMed

    Zhang, Man; Liu, Xu-Hua; He, Xiong-Kui; Zhang, Lu-Da; Zhao, Long-Lian; Li, Jun-Hui

    2010-05-01

    In the present paper, taking 66 wheat samples for testing materials, ridge regression technology in near-infrared (NIR) spectroscopy quantitative analysis was researched. The NIR-ridge regression model for determination of protein content was established by NIR spectral data of 44 wheat samples to predict the protein content of the other 22 samples. The average relative error was 0.015 18 between the predictive results and Kjeldahl's values (chemical analysis values). And the predictive results were compared with those values derived through partial least squares (PLS) method, showing that ridge regression method was deserved to be chosen for NIR spectroscopy quantitative analysis. Furthermore, in order to reduce the disturbance to predictive capacity of the quantitative analysis model resulting from irrelevant information, one effective way is to screen the wavelength information. In order to select the spectral information with more content information and stronger relativity with the composition or the nature of the samples to improve the model's predictive accuracy, ridge regression was used to select wavelength information in this paper. The NIR-ridge regression model was established with the spectral information at 4 wavelength points, which were selected from 1 297 wavelength points, to predict the protein content of the 22 samples. The average relative error was 0.013 7 and the correlation coefficient reached 0.981 7 between the predictive results and Kjeldahl's values. The results showed that ridge regression was able to screen the essential wavelength information from a large amount of spectral information. It not only can simplify the model and effectively reduce the disturbance resulting from collinearity information, but also has practical significance for designing special NIR analysis instrument for analyzing specific component in some special samples. PMID:20672604

  14. Quantitatively resolving multivalent interactions on a macroscopic scale using force spectroscopy.

    PubMed

    Hu, Qiongzheng; Yang, Haopeng; Wang, Yuhong; Xu, Shoujun

    2016-02-23

    Multivalent interactions remain difficult to be characterized and consequently controlled, particularly on a macroscopic scale. Using force-induced remnant magnetization spectroscopy (FIRMS), we have resolved the single-, double-, and triple-biotin-streptavidin interactions, multivalent DNA interactions and CXCL12-CXCR4 interactions on millimetre-scale surfaces. Our results establish FIRMS as a viable method for systematic resolution and controlled formation of multivalent interactions. PMID:26864087

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

    NASA Astrophysics Data System (ADS)

    Shao, Yongni; He, Yong; Mao, Jingyuan

    2007-09-01

    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.

  16. Quantitative polymorph contaminant analysis in tablets using Raman and near infra-red spectroscopies.

    PubMed

    Hennigan, Michelle C; Ryder, Alan G

    2013-01-01

    The detection and quantification of alternate polymorphs of active pharmaceutical ingredients (APIs), particularly at low concentrations is a key issue for the manufacture and analysis of solid-state formulations. Each polymorph can possess unique physical and chemical properties which in turn can directly affect factors such as solubility and bioavailability. Near infra-red (NIR) and Raman spectroscopies can be used for the rapid characterisation and quantification of polymorphs in solid samples. In this study we have generated a model tablet system with two excipients and a 10% API concentration, where the API is a mixture of the FII and FIII polymorphs of piracetam. Using transmission Raman spectroscopy (TRS) and NIR spectroscopy it was possible to detect FII polymorph contamination in these model tablets with limits of detection (LODs) of 0.6 and 0.7%, respectively, with respect to the total tablet weight (or ∼6-7% of the API content). The TRS method is the superior method because of the speed of analysis (∼6s per sample), better sampling statistics, and because the sharper, more resolved bands in the Raman spectra allowed for easier interpretation of the spectral data. In addition the TRS used here provides facile access to the low frequency wavenumber region for analysis of solid-state lattice modes. PMID:23146243

  17. Determination of optical properties of turbid media spanning visible and near-infrared regimes via spatially modulated quantitative spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    We present a novel, noncontact method for the determination of quantitative optical properties of turbid media from 430 to 1050 nm. Through measuring the broadband reflectance from an unknown sample as a function of the spatial frequency of the projected illumination patterns, the absolute absorption and reduced scattering coefficients can be calculated without a priori assumptions of the chromophores present. This technique, which is called spatially modulated quantitative spectroscopy (SMoQS), was validated through the quantification of optical properties of homogenous liquid phantoms with known concentrations of absorbers and scatterers. The properties of the phantoms were recovered across the range of values prepared with R2 values of 0.985 and 0.996 for absorption and reduced scattering, respectively. A measurement was also performed on skin tissue as a demonstration of the method's performance in vivo. The resultant absorption spectrum was well described by a multichromophore fit, and the quantitative values for oxy- and deoxyhemoglobin, water, and melanin were within published ranges for skin.

  18. Quantitative detection of uric acid by electrochemical-surface enhanced Raman spectroscopy using a multilayered Au/Ag substrate.

    PubMed

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

    2015-01-01

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

  19. Determination of optical properties of turbid media spanning visible and near-infrared regimes via spatially modulated quantitative spectroscopy

    PubMed Central

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

    2010-01-01

    We present a novel, noncontact method for the determination of quantitative optical properties of turbid media from 430 to 1050 nm. Through measuring the broadband reflectance from an unknown sample as a function of the spatial frequency of the projected illumination patterns, the absolute absorption and reduced scattering coefficients can be calculated without a priori assumptions of the chromophores present. This technique, which is called spatially modulated quantitative spectroscopy (SMoQS), was validated through the quantification of optical properties of homogenous liquid phantoms with known concentrations of absorbers and scatterers. The properties of the phantoms were recovered across the range of values prepared with R2 values of 0.985 and 0.996 for absorption and reduced scattering, respectively. A measurement was also performed on skin tissue as a demonstration of the method’s performance in vivo. The resultant absorption spectrum was well described by a multichromophore fit, and the quantitative values for oxy- and deoxyhemoglobin, water, and melanin were within published ranges for skin. PMID:20210486

  20. A novel method for quantitative analysis of acetylacetone and ethyl acetoacetate by fluorine-19 nuclear magnetic spectroscopy.

    PubMed

    Zhou, Lulin; Li, Cheng; Weng, Xinchu

    2016-03-01

    A new method utilization of NMR spectra was developed for structural and quantitative analysis of enol forms of acetylacetone and ethyl acetoacetate. Acetylacetone and ethyl acetoacetate were determined by (19) F NMR upon derivatisation with р-fluorobenzoyl chloride. The base-catalyzed derivatives of acetylacetone and ethyl acetoacetate reaction with р-fluorobenzoyl chloride were analyzed by (1) H and (13) C NMR spectroscopies. E and Z configurations of acetylacetone and ethyl acetoacetate were separated and purified by thin layer chromatography. In addition, the ability of (19) F NMR for quantitative analysis of acetylacetone by integration of the appropriate signals of the derivatives were tested and compared. The results further testified the enol forms of acetylacetone and ethyl acetoacetate and the feasibility of (19) F NMR method. This method can be potentially used to characterize E and Z isomers and quantitatively analyze E/Z ratio of β-diketone and β-ketoester homologues. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26521683

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

    PubMed

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

    2008-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  4. Quantitative Evaluation of the Carbon Hybridization State by Near Edge X-ray Absorption Fine Structure Spectroscopy.

    PubMed

    Mangolini, Filippo; McClimon, J Brandon; Carpick, Robert W

    2016-03-01

    The characterization of the local bonding configuration of carbon in carbon-based materials is of paramount importance since the properties of such materials strongly depend on the distribution of carbon hybridization states, the local ordering, and the degree of hydrogenation. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectroscopy is one of the most powerful techniques for gaining insights into the bonding configuration of near-surface carbon atoms. The common methodology for quantitatively evaluating the carbon hybridization state using C 1s NEXAFS measurements, which is based on the analysis of the sample of interest and of a highly ordered pyrolytic graphite (HOPG) reference sample, was reviewed and critically assessed, noting that inconsistencies are found in the literature in applying this method. A theoretical rationale for the specific experimental conditions to be used for the acquisition of HOPG reference spectra is presented together with the potential sources of uncertainty and errors in the correctly computed fraction of sp(2)-bonded carbon. This provides a specific method for analyzing the distribution of carbon hybridization state using NEXAFS spectroscopy. As an illustrative example, a hydrogenated amorphous carbon film was analyzed using this method and showed good agreement with X-ray photoelectron spectroscopy (which is surface sensitive). Furthermore, the results were consistent with analysis from Raman spectroscopy (which is not surface sensitive), indicating the absence of a structurally different near-surface region in this particular thin film material. The present work can assist surface scientists in the analysis of NEXAFS spectra for the accurate characterization of the structure of carbon-based materials. PMID:26814796

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

    NASA Astrophysics Data System (ADS)

    Sharp, James C.; Campbell, Charles T.

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Sulub, Yusuf Ismail

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

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

    SciTech Connect

    Shao Yongni; He Yong; Mao Jingyuan

    2007-09-01

    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.

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

    PubMed Central

    Lau, Peter C.Y.; Dutcher, John R.; Beveridge, Terry J.; Lam, Joseph S.

    2009-01-01

    Bacterial biofilms are the most prevalent mode of bacterial growth in nature. Adhesive and viscoelastic properties of bacteria play important roles at different stages of biofilm development. Following irreversible attachment of bacterial cells onto a surface, a biofilm can grow in which its matrix viscoelasticity helps to maintain structural integrity, determine stress resistance, and control ease of dispersion. In this study, a novel application of force spectroscopy was developed to characterize the surface adhesion and viscoelasticity of bacterial cells in biofilms. By performing microbead force spectroscopy with a closed-loop atomic force microscope, we accurately quantified these properties over a defined contact area. Using the model gram-negative bacterium Pseudomonas aeruginosa, we observed that the adhesive and viscoelastic properties of an isogenic lipopolysaccharide mutant wapR biofilm were significantly different from those measured for the wild-type strain PAO1 biofilm. Moreover, biofilm maturation in either strain also led to prominent changes in adhesion and viscoelasticity. To minimize variability in force measurements resulting from experimental parameter changes, we developed standardized conditions for microbead force spectroscopy to enable meaningful comparison of data obtained in different experiments. Force plots measured under standard conditions showed that the adhesive pressures of PAO1 and wapR early biofilms were 34 ± 15 Pa and 332 ± 47 Pa, respectively, whereas those of PAO1 and wapR mature biofilms were 19 ± 7 Pa and 80 ± 22 Pa, respectively. Fitting of creep data to a Voigt Standard Linear Solid viscoelasticity model revealed that the instantaneous and delayed elastic moduli in P. aeruginosa were drastically reduced by lipopolysaccharide deficiency and biofilm maturation, whereas viscosity was decreased only for biofilm maturation. In conclusion, we have introduced a direct biophysical method for simultaneously quantifying adhesion and viscoelasticity in bacterial biofilms under native conditions. This method could prove valuable for elucidating the contribution of genetic backgrounds, growth conditions, and environmental stresses to microbial community physiology. PMID:19348775

  9. Quantitative determination of absolute organohalogen concentrations in environmental samples by X-ray absorption spectroscopy.

    PubMed

    Leri, Alessandra C; Hay, Michael B; Lanzirotti, Antonio; Rao, William; Myneni, Satish C B

    2006-08-15

    An in situ procedure for quantifying total organic and inorganic Cl concentrations in environmental samples based on X-ray absorption near-edge structure (XANES) spectroscopy has been developed. Cl 1s XANES spectra reflect contributions from all Cl species present in a sample, providing a definitive measure of total Cl concentration in chemically heterogeneous samples. Spectral features near the Cl K-absorption edge provide detailed information about the bonding state of Cl, whereas the absolute fluorescence intensity of the spectra is directly proportional to total Cl concentration, allowing for simultaneous determination of Cl speciation and concentration in plant, soil, and natural water samples. Absolute Cl concentrations are obtained from Cl 1s XANES spectra using a series of Cl standards in a matrix of uniform bulk density. With the high sensitivity of synchrotron-based X-ray absorption spectroscopy, Cl concentration can be reliably measured down to the 5-10 ppm range in solid and liquid samples. Referencing the characteristic near-edge features of Cl in various model compounds, we can distinguish between inorganic chloride (Cl(inorg)) and organochlorine (Cl(org)), as well as between aliphatic Cl(org) and aromatic Cl(org), with uncertainties in the range of approximately 6%. In addition, total organic and inorganic Br concentrations in sediment samples are quantified using a combination of Br 1s XANES and X-ray fluorescence (XRF) spectroscopy. Br concentration is detected down to approximately 1 ppm by XRF, and Br 1s XANES spectra allow quantification of the Br(inorg) and Br(org) fractions. These procedures provide nondestructive, element-specific techniques for quantification of Cl and Br concentrations that preclude extensive sample preparation. PMID:16906715

  10. A highly linear superconducting bolometer for quantitative THz Fourier transform spectroscopy.

    PubMed

    Kehrt, Mathias; Monte, Christian; Beyer, Jörn; Hollandt, Jörg

    2015-05-01

    A superconducting transition edge sensor (TES) bolometer operating in the spectral range from 0.1 THz to 3 THz was designed. It is especially intended for Fourier transform spectroscopy and features a higher dynamic range and a highly linear response at a similar response compared to commercially available silicon composite bolometers. The design is based on a thin film metal mesh absorber, a superconducting thermistor and Si3N4 membrane technology. A prototype was set up, characterized and successfully used in first applications. PMID:25969213

  11. Quantitative multi-elemental laser-induced breakdown spectroscopy using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Motto-Ros, V.; Koujelev, A. S.; Osinski, G. R.; Dudelzak, A. E.

    2008-03-01

    The Laser-Induced Breakdown Spectroscopy (LIBS) is an emerging technique with great potential in atomic elemental analysis in many areas, particularly, in space exploration. In this paper, an algorithm for automated identification of elements and measurements of their concentrations in rocks and soils, as well as its experimental validation are presented. The proposed approach is based on the artificial neural network (ANN). We demonstrate that the ANN algorithm works successfully for all major elements of geological interest tested on natural rock and soil samples.

  12. Quantitative generalized ratiometric fluorescence spectroscopy for turbid media based on probe encapsulated by biologically localized embedding.

    PubMed

    Yan, Xiu-Fang; Chen, Zeng-Ping; Cui, Yin-Yin; Hu, Yuan-Liang; Yu, Ru-Qin

    2016-05-19

    PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFMGRP) with a view to simplify the design of PEBBLEs and hence further extend their application potentials. The effectiveness of QFMGRP has been tested on the quantitative determination of free Ca(2+) in both simulated and real turbid media using a Ca(2+) sensitive PEBBLE nanosensor encapsulating Rhod-2 and eosin B inside the micropores of stable polyacrylamide matrix. Experimental results demonstrated that QFMGRP could realize precise and accurate quantification of free Ca(2+) in turbid samples, even though there is serious overlapping between the fluorescence excitation peaks of eosin B and Ca(2+) bound Rhod-2. The average relative predictive error value of QFMGRP for the test simulated turbid samples was 5.9%, about 2-4 times lower than the corresponding values of partial least squares calibration model and the empirical ratiometric model based on the ratio of fluorescence intensities at the excitation peaks of Ca(2+) bound Rhod-2 and eosin B. The recovery rates of QFMGRP for the real and spiked turbid samples varied from 93.1% to 101%, comparable to the corresponding results of atomic absorption spectrometry. PMID:27126788

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

    PubMed Central

    2012-01-01

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

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

    PubMed

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

    2014-10-24

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

  15. Quantitative real-time monitoring of dryer effluent using fiber optic near-infrared spectroscopy.

    PubMed

    Harris, S C; Walker, D S

    2000-09-01

    This paper describes a method for real-time quantitation of the solvents evaporating from a dryer. The vapor stream in the vacuum line of a dryer was monitored in real time using a fiber optic-coupled acousto-optic tunable filter near-infrared (AOTF-NIR) spectrometer. A balance was placed in the dryer, and mass readings were recorded for every scan of the AOTF-NIR. A partial least-squares (PLS) calibration was subsequently built based on change in mass over change in time for solvents typically used in a chemical manufacturing plant. Controlling software for the AOTF-NIR was developed. The software collects spectra, builds the PLS calibration model, and continuously fits subsequently collected spectra to the calibration, allowing the operator to follow the mass loss of solvent from the dryer. The results indicate that solvent loss can be monitored and quantitated in real time using NIR for the optimization of drying times. These time-based mass loss values have also been used to calculate "dynamic" vapor density values for the solvents. The values calculated are in agreement with values determined from the ideal gas law and could prove valuable as tools to measure temperature or pressure indirectly. PMID:10944383

  16. The quantitative determination of FeS2 phases in coal by means of57Fe Mssbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Evans, B. J.; King, Hobart M.; Renton, John J.; Stiller, A.

    1990-07-01

    A knowledge of the concentration of pyrite and marcasite in coals can provide important insight into the genesis of coal deposits. Determinations of the relative amounts of pyrite and marcasite by traditional methods of coal analysis are, however, beset with many difficulties. Using57Fe Mssbauer spectroscopy and a mild chemical treatment with hydrofluoric acid, a technique has been devised for the quantitative determination of the relative concentrations of pyrite and marcasite in samples of whole coals or their low-temperature ashes. The sample preparation procedure is comparable to less accurate methods. Good qualitative agreement has been obtained between ore microscopic and Mssbauer spectroscopic techniques for a series of extensively investigated whole coal samples.

  17. Distribution of Hydroxyl Groups in Kukersite Shale Oil: Quantitative Determination Using Fourier Transform Infrared (FT-IR) Spectroscopy.

    PubMed

    Baird, Zachariah Steven; Oja, Vahur; Järvik, Oliver

    2015-05-01

    This article describes the use of Fourier transform infrared (FT-IR) spectroscopy to quantitatively measure the hydroxyl concentrations among narrow boiling shale oil cuts. Shale oil samples were from an industrial solid heat carrier retort. Reference values were measured by titration and were used to create a partial least squares regression model from FT-IR data. The model had a root mean squared error (RMSE) of 0.44 wt% OH. This method was then used to study the distribution of hydroxyl groups among more than 100 shale oil cuts, which showed that hydroxyl content increased with the average boiling point of the cut up to about 350 °C and then leveled off and decreased. PMID:25811170

  18. Towards quantitative depth-profile analysis using laser-induced plasma spectroscopy: investigation of galvannealed coatings on steel

    NASA Astrophysics Data System (ADS)

    St-Onge, L.; Sabsabi, M.

    2000-03-01

    Laser-induced plasma spectroscopy (LIPS) is applied to depth-profile analysis, with the particular goal of examining how LIPS depth profiles can be fully calibrated. For this purpose, we concentrate on the representative case of galvannealed coatings on steel (i.e. annealed zinc-coated steel). In particular, a method is proposed wherein the second derivative of the zinc intensity profile enables the determination of the coating/substrate interface position. Calibration for the major elements (iron and zinc) is based on a non-linear relationship between the iron-to-zinc line intensity ratio and the iron-to-zinc concentration ratio. Quantitative depth profiles of three elements (Al, Fe and Zn) are obtained for two galvannealed samples. The iron profiles are found to be in broad agreement with those obtained by transmission electron microscopy/energy dispersive X-ray spectrometry.

  19. Performance evaluation of Laser Induced Breakdown Spectroscopy (LIBS) for quantitative analysis of rare earth elements in phosphate glasses

    NASA Astrophysics Data System (ADS)

    Devangad, Praveen; Unnikrishnan, V. K.; Nayak, Rajesh; Tamboli, M. M.; Muhammed Shameem, K. M.; Santhosh, C.; Kumar, G. A.; Sardar, D. K.

    2016-02-01

    In the current study, we have determined the elemental compositions of synthesized rare earth doped phosphate glasses using a laboratory Laser-Induced Breakdown Spectroscopy (LIBS) system. LIBS spectra of this rare earth (samarium (Sm), thulium (Tm) and ytterbium (Yb)) doped glass samples with known composition are recorded using a highly sensitive detector. Major atomic emission lines of Sm, Tm and Yb found in LIBS spectra are reported. By considering the atomic emission line of phosphorous as an internal standard, calibration curves were constructed for all the rare earth concentrations. Very good linear regression coefficient (R2) values were obtained using this technique. Analytical predictive skill of LIBS was studied further using leave-one-out method. Low values of the reported correlation uncertainty between measured LIBS concentration ratio and certified concentration ratio confirms that LIBS technique has great potential for quantitative analysis of rare earth elements in glass matrix.

  20. [Quantitative analysis of contents in compound fertilizer and application research using near infrared reflectance spectroscopy].

    PubMed

    Song, Le; Zhang, Hong; Ni, Xiao-Yu; Wu, Lin; Liu, Bin-Mei; Yu, Li-Xiang; Wang, Qi; Wu, Yue-Jin

    2014-01-01

    In the present study, a new approach to fast determining the content of urea, biuret and moisture in compound fertilizer composed of urea, ammonium dihydrogenphosphate and potassium chloride was proposed by using near infrared diffuse reflectance spectroscopy. After preprocessing the original spectrum, partial least squares (PLS) models of urea, biuret and moisture were built with the R2 values of 0.9861, 0.9770 and 0.9713 respectively, the root mean square errors of cross validation were 2.59, 0.38, 0.132 respectively. And the prediction correlation factors were 0.9733, 0.9215 and 0.9679 respectively. The authors detected six kinds of compound fertilizer in market for the model verification, the correlation factors were 0.9237, 0.9786 and 0.9874 respectively. The data implied that the new method can be used for situ quality control in the production process of compound fertilizer. PMID:24783536

  1. Quantitation of Organics in Supercritical Fluid Aging Experiments Using FTIR Spectroscopy

    SciTech Connect

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

    2004-03-31

    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.

  2. Quantitative analysis of mebendazole polymorphs in pharmaceutical raw materials using near-infrared spectroscopy.

    PubMed

    da Silva, Vitor H; Gonçalves, Jacqueline L; Vasconcelos, Fernanda V C; Pimentel, M Fernanda; Pereira, Claudete F

    2015-11-10

    This work evaluates the feasibility of using NIR spectroscopy for quantification of three polymorphs of mebendazole (MBZ) in pharmaceutical raw materials. Thirty ternary mixtures of polymorphic forms of MBZ were prepared, varying the content of forms A and C from 0 to 100% (w/w), and for form B from 0 to 30% (w/w). Reflectance NIR spectra were used to develop partial least square (PLS) regression models using all spectral variables and the variables with significant regression coefficients selected by the Jack-Knife algorithm (PLS/JK). MBZ polymorphs were quantified with RMSEP values of 2.37% w/w, 1.23% w/w and 1.48% w/w for polymorphs A, B and C, respectively. This is an easy, fast and feasible method for monitoring the quality of raw pharmaceutical materials of MBZ according to polymorph purity. PMID:26320077

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

    PubMed Central

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

    2013-01-01

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

  4. Quantitative spectroscopy on individual wire, slot, bow-tie, rectangular, and square-shaped optical antennas.

    PubMed

    Husnik, Martin; Niegemann, Jens; Busch, Kurt; Wegener, Martin

    2013-11-15

    By using a recently introduced approach combining a focus-modulation technique with a common-path interferometer, we measure quantitatively the extinction, scattering, and absorption cross-section spectra of individual optical antennas. The experimental results on thin-wire antennas, slot antennas, bow-tie antennas, rectangular antennas, and square-shaped antennas resonating at around 1.4 μm wavelength are discussed. We find increased resonant scattering cross sections for the latter four antennas compared to the thin-wire antenna, both in absolute terms and relative to the absorption cross section. The square-shaped antenna's resonant extinction cross section approaches the limit of a coherent point dipole. However, the ratio of the resonant extinction cross section to the geometrical cross section of 38 is largest for the simple thin-wire antenna. PMID:24322083

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

    SciTech Connect

    Farrow, R.; Rakestraw, D.; Paul, P.; Lucht, R.; Danehy, P.; Friedman-Hill, E.; Germann, G.

    1993-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    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.

  7. Quantitative analysis of oxide materials by laser-induced breakdown spectroscopy with argon as an internal standard

    NASA Astrophysics Data System (ADS)

    Lasheras, R. J.; Bello-Gálvez, C.; Anzano, J. M.

    2013-04-01

    Laser-induced breakdown spectroscopy (LIBS) is demonstrated as a quantitative technique for geochemical analysis. This study demonstrates the applicability of LIBS to multielemental analysis of minerals using argon as an internal standard. Laser-induced breakdown spectroscopy has been applied to measure elements in oxide form. In the present study, the contents of several oxides, such as Fe2O3, CaO and MgO, in geological samples from the Tierga Mine (Zaragoza, Spain) were analyzed by LIBS. An argon environment was used to eliminate interference from air at atmospheric pressure. Furthermore, argon was used as an internal standard. The result was enhanced signal and enhanced linearity of the calibration curves. The Fe2O3, CaO and MgO concentrations determined by LIBS were compared with the results obtained using another analytical technique, inductively coupled plasma optical emission spectrometry (ICP-OES). The concentrations found using LIBS were in good agreement with the values obtained by ICP-OES.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

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

    PubMed Central

    Kumar, Prashant; Nagarajan, Rajamani

    2013-01-01

    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

  10. A Comparison of Multivariate and Pre-Processing Methods for Quantitative Laser-Induced Breakdown Spectroscopy of Geologic Samples

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    The ChemCam instrument selected for the Curiosity rover is capable of remote laser-induced breakdown spectroscopy (LIBS).[1] We used a remote LIBS instrument similar to ChemCam to analyze 197 geologic slab samples and 32 pressed-powder geostandards. The slab samples are well-characterized and have been used to validate the calibration of previous instruments on Mars missions, including CRISM [2], OMEGA [3], the MER Pancam [4], Mini-TES [5], and Moessbauer [6] instruments and the Phoenix SSI [7]. The resulting dataset was used to compare multivariate methods for quantitative LIBS and to determine the effect of grain size on calculations. Three multivariate methods - partial least squares (PLS), multilayer perceptron artificial neural networks (MLP ANNs) and cascade correlation (CC) ANNs - were used to generate models and extract the quantitative composition of unknown samples. PLS can be used to predict one element (PLS1) or multiple elements (PLS2) at a time, as can the neural network methods. Although MLP and CC ANNs were successful in some cases, PLS generally produced the most accurate and precise results.

  11. Quantitative measurement of intracellular transport of nanocarriers by spatio-temporal image correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Coppola, S.; Pozzi, D.; Candeloro De Sanctis, S.; Digman, M. A.; Gratton, E.; Caracciolo, G.

    2013-03-01

    Spatio-temporal image correlation spectroscopy (STICS) is a powerful technique for assessing the nature of particle motion in complex systems although it has been rarely used to investigate the intracellular dynamics of nanocarriers so far. Here we introduce a method for characterizing the mode of motion of nanocarriers and for quantifying their transport parameters on different length scales from single-cell to subcellular level. Using this strategy we were able to study the mechanisms responsible for the intracellular transport of DOTAP-DOPC/DNA (DOTAP: 1,2-dioleoyl-3-trimethylammonium-propane; DOPC: dioleoylphosphocholine) and DC-Chol-DOPE/DNA (DC-Chol: 3?-[N-(N,N-dimethylaminoethane)-carbamoyl] cholesterol; DOPE: dioleoylphosphatidylethanolamine) lipoplexes in CHO-K1 (CHO: Chinese hamster ovary) live cells. Measurement of both diffusion coefficients and velocity vectors (magnitude and direction) averaged over regions of the cell revealed the presence of distinct modes of motion. Lipoplexes diffused slowly on the cell surface (diffusion coefficient: D ? 0.003 ?m2 s-1). In the cytosol, the lipoplexes motion was characterized by active transport with average velocity v ? 0.03 ?m2 s-1 and random motion. The method permitted us to generate an intracellular transport map showing several regions of concerted motion of lipoplexes.

  12. Vibrational spectroscopy and microspectroscopy analyzing qualitatively and quantitatively pharmaceutical hot melt extrudates.

    PubMed

    Netchacovitch, L; Thiry, J; De Bleye, C; Chavez, P-F; Krier, F; Sacré, P-Y; Evrard, B; Hubert, Ph; Ziemons, E

    2015-09-10

    Since the last decade, more and more Active Pharmaceutical Ingredient (API) candidates have poor water solubility inducing low bioavailability. These molecules belong to the Biopharmaceutical Classification System (BCS) classes II and IV. Thanks to Hot-Melt Extrusion (HME), it is possible to incorporate these candidates in pharmaceutical solid forms. Indeed, HME increases the solubility and the bioavailability of these drugs by encompassing them in a polymeric carrier and by forming solid dispersions. Moreover, in 2004, the FDA's guidance initiative promoted the usefulness of Process Analytical Technology (PAT) tools when developing a manufacturing process. Indeed, the main objective when developing a new pharmaceutical process is the product quality throughout the production chain. The trend is to follow this parameter in real-time in order to react immediately when there is a bias. Vibrational spectroscopic techniques, NIR and Raman, are useful to analyze processes in-line. Moreover, off-line Raman microspectroscopy is more and more used when developing new pharmaceutical processes or when analyzing optimized ones by combining the advantages of Raman spectroscopy and imaging. It is an interesting tool for homogeneity and spatial distribution studies. This review treats about spectroscopic techniques analyzing a HME process, as well off-line as in-line, presenting their advantages and their complementarities. PMID:25704954

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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).

  14. Quantitative endoscopic imaging elastic scattering spectroscopy: model system/tissue phantom validation

    NASA Astrophysics Data System (ADS)

    Lindsley, E. H.; Farkas, D. L.

    2008-02-01

    We have designed and built an imaging elastic scattering spectroscopy endoscopic instrument for the purpose of detecting cancer in vivo. As part of our testing and validation of the system, known targets representing potential disease states of interest were constructed using polystyrene beads of known average diameter and TiO II crystals embedded in a two-layer agarose gel. Final construction geometry was verified using a dissection microscope. The phantoms were then imaged using the endoscopic probe at a known incident angle, and the results compared to model predictions. The mathematical model that was used combines classic ray-tracing optics with Mie scattering to predict the images that would be observed by the probe at a given physical distance from a Mie-regime scattering media. This model was used generate the expected observed response for a broad range of parameter values, and these results were then used as a library to fit the observed data from the phantoms. Compared against the theoretical library, the best matching signal correlated well with known phantom material dimensions. These results lead us to believe that imaging elastic scattering can be useful in detection/diagnosis, but further refinement of the device will be necessary to detect the weak signals in a real clinical setting.

  15. [Quantitative analysis of Ba and Sr in soil using laser-induced breakdown spectroscopy].

    PubMed

    Chen, Tian-Bing; Yao, Ming-Yin; Liu, Mu-Hua; Lei, Ze-Jian; Peng, Qiu-Mei; Xu, Yuan; Zhang, Xu

    2012-06-01

    Laser induced breakdown spectroscopy (LIBS) was applied to measure barium and strontium elements in soil. The emission spectrum was emitted as the plasma was cooling off, which was collected and analyzed by fiber spectrometer. Spectral lines of barium (BaII line at 455.41 nm) and strontium (SrI line at 460.73 nm) were separately used for the determining. In order to reduce the error, fitting of the spectra by using Lorenizian function was used, the datum was preprocessed and the net intensity value of the spectra was collected. A signal intensity in the proper range of the characteristic spectrum was chosen as the interior label. A calibration curve was drawn according to the ratio between the value of the analytical line and the interior scaling line. The correlation coefficient between the content and the intensity ratio of Ba and Sr were up to 0.990 0 and 0.990 6. The content of Ba and Sr was inversed by means of the intensity scaling method. As a result, the relative deviations between the content values and the standard values of Ba and Sr were 5.7% and 5.1% respectively. PMID:22870660

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

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    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.

  17. Quantitative analysis of α-mangostin in hydrophilic ointment using near-infrared spectroscopy.

    PubMed

    Peerapattana, Jomjai; Otsuka, Kuniko; Hattori, Yusuke; Otsuka, Makoto

    2015-03-01

    The objective of this research was to quantify the α-mangostin content in mangosteen pericarp (MP) ointment as a colloidal dispersion using near-infrared (NIR) spectroscopy. Various concentrations of MP (IP and EP) ointments containing both internal and external pericarps were prepared and the NIR spectra of these ointments were measured. The NIR spectrum of each ointment was correlated with α-mangostin concentration by partial least square (PLS) regression. Validation of the models was performed and their predictive ability was also investigated. The equation and R(2) value for the prediction of α-mangostin concentration in IP ointment were y=0.9843x+0.4441 and 0.9730 and those in EP ointment were y=0.9569x+0.1142 and 0.9136, respectively. The biases of the IP and EP ointment models were 0.23 and 0.00, respectively. The results showed that NIR could be a useful tool for the quality control of herbal medicine in hydrophilic ointment without any sample preparation. It could predict α-mangostin content in hydrophilic ointment at very low concentration with sufficient accuracy. PMID:24517571

  18. Elastic-scattering spectroscopy for quantitative measurement of chemotherapy and PDT drug concentrations in vivo

    NASA Astrophysics Data System (ADS)

    Bigio, Irving J.; Mourant, Judith R.; Los, Gerrit

    1999-01-01

    We have applied elastic-scattering spectroscopy (ESS) for noninvasive, real-time in vivo measurement of the concentrations of certain drugs in tissue, utilizing a simple fiber-optic-probe spectroscopic system. The system uses a broadband light source, enabling the detection of compounds with absorption bands in most regions of the visible, as well as the NIR to 1700 nm. Subcutaneous tumors were grown in 4 Nude mice; the mice were treated with one of two chemotherapy agents, and the ESS system was used to perform pharmacokinetics measurements on the tumors following drug administration. Time histories of the drug concentrations in the tumors agreed with the known pharmacokinetics of the two drugs, and HPLC assays following sacrifice showed good correlation with the ESS values. Most photodynamic therapy agents and many chemotherapy drugs, including any that are not fluorescent, are ideal candidates for the ESS system. The measurement can be calibrated absolutely, and is not susceptible to problems associated with fluorescence assay methods.

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

    PubMed Central

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

    2009-01-01

    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

  20. Electrically Injected UV-Visible Nanowire Lasers

    SciTech Connect

    Wang, George T.; Li, Changyi; Li, Qiming; Liu, Sheng; Wright, Jeremy Benjamin; Brener, Igal; Luk, Ting -Shan; Chow, Weng W.; Leung, Benjamin; Figiel, Jeffrey J.; Koleske, Daniel D.; Lu, Tzu-Ming

    2015-09-01

    There is strong interest in minimizing the volume of lasers to enable ultracompact, low-power, coherent light sources. Nanowires represent an ideal candidate for such nanolasers as stand-alone optical cavities and gain media, and optically pumped nanowire lasing has been demonstrated in several semiconductor systems. Electrically injected nanowire lasers are needed to realize actual working devices but have been elusive due to limitations of current methods to address the requirement for nanowire device heterostructures with high material quality, controlled doping and geometry, low optical loss, and efficient carrier injection. In this project we proposed to demonstrate electrically injected single nanowire lasers emitting in the important UV to visible wavelengths. Our approach to simultaneously address these challenges is based on high quality III-nitride nanowire device heterostructures with precisely controlled geometries and strong gain and mode confinement to minimize lasing thresholds, enabled by a unique top-down nanowire fabrication technique.

  1. Fiber optic based multiparametric spectroscopy in vivo: Toward a new quantitative tissue vitality index

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  2. Quantitative resonance Raman spectroscopy of N-acetylpyrrolidine in aqueous solution

    SciTech Connect

    Harhay, G.P.; Hudson, B.S. )

    1993-08-05

    The resonance Raman spectra of aqueous solutions of N-acetylpyrrolidine are determined at seven excitation frequencies from 40 660 to 53 130 cm[sup [minus]1] spanning the first strong absorption band which is broad and diffuse The resonance Raman spectra are dominated by the single amide II[prime]-like vibration at 1485 cm[sup [minus]1] and its overtones of up to five quanta. Absolute resonance Raman cross sections are determined for these fundamental and overtone transitions at each excitation wavelength by reference to an internal standard of sodium perchlorate. A quantitative analysis of these data and the broad absorption spectrum is made on the basis of a model for the electronic excitation that includes the effects of inhomogeneous broadening. The observation of only a single enhanced vibrational normal mode, with the assumption that there is no Duschinsky rotation upon electronic excitation, makes this a particularly simple case for detailed analysis. A reasonably good fit to the experimental data is obtained using standard assumptions of Lorentzian inhomogeneous broadening and A-term (Condom) Raman scattering. In this fitting procedure, the integrated absorption spectrum determines the transition dipole length. 43 refs., 4 figs., 2 tabs.

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

    PubMed

    Szostak, Roman; Mazurek, Sylwester

    2002-01-01

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

  4. Quantitative determination of aflatoxin B1 concentration in acetonitrile by chemometric methods using terahertz spectroscopy.

    PubMed

    Ge, Hongyi; Jiang, Yuying; Lian, Feiyu; Zhang, Yuan; Xia, Shanhong

    2016-10-15

    Aflatoxins contaminate and colonize agricultural products, such as grain, and thereby potentially cause human liver carcinoma. Detection via conventional methods has proven to be time-consuming and complex. In this paper, the terahertz (THz) spectra of aflatoxin B1 in acetonitrile solutions with concentration ranges of 1-50μg/ml and 1-50μg/l are obtained and analyzed for the frequency range of 0.4-1.6THz. Linear and nonlinear regression models are constructed to relate the absorption spectra and the concentrations of 160 samples using the partial least squares (PLS), principal component regression (PCR), support vector machine (SVM), and PCA-SVM methods. Our results indicate that PLS and PCR models are more accurate for the concentration range of 1-50μg/ml, whereas SVM and PCA-SVM are more accurate for the concentration range of 1-50μg/l. Furthermore, ten unknown concentration samples extracted from mildewed maize are analyzed quantitatively using these methods. PMID:27173565

  5. Vibrational spectroscopy and chemometrics for rapid, quantitative analysis of bitter acids in hops (Humulus lupulus).

    PubMed

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

    2014-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  8. [Quantitative Analysis of the Hydration Process of Mine Gas Mixture Based on Raman Spectroscopy].

    PubMed

    Zhang, Bao-yong; Yu, Yue; Wu, Qiang; Gao, Xia

    2015-07-01

    The research on micro crystal structure of mine gas hydrate is especially significant for the technology of gas hydrate separation. Using Raman spectroscopy to observe hydration process of 3 kinds of mine gas mixture on line which contains high concentration of carbon dioxide, this experiment obtained the information of the hydrate crystals including large and small cage occupancy. Meanwhile obtained the hydration number indirectly based on the statistical thermodynamic model of van der Waals and Platteeuw. The results show that cage occupancy and hydration number of mine gas hydrates change little during different growth stages. The large cages of hydrate phases are nearly full occupied by carbon dioxide and methane molecules together, with the occupancy ratios between 97.70% and 98.68%. Most of the guest molecules in large cages is carbon dioxide (78.58%-94.09%) and only a few (4.52%-19.12%) is filled with methane, it is because carbon dioxide concentration in the gas sample is higher than methane and there is competition between them. However the small cage occupancy ratios is generally low in the range from 17.93% to 82.41%, and the guest molecules are all methane. With the increase of methane concentration in gas sample, the cage occupancy both large and small which methane occupied has increased, meanwhile the large cage occupancy which methane occupied is lower than small cage. The hydration numbers of mine gas hydrate during different growth stages are between 6.13 and 7.33. Small cage occupancy has increased with the increase of methane concentration, this lead to hydration number decreases. Because of the uneven distribution of hydrate growth, the hydration numbers of 3 kinds of gas samples show irregular change during different growth stages. PMID:26717751

  9. Quantitative, comparable coherent anti-Stokes Raman scattering (CARS) spectroscopy: correcting errors in phase retrieval

    NASA Astrophysics Data System (ADS)

    Camp, Charles H., Jr.; Lee, Young Jong; Cicerone, Marcus T.

    2016-04-01

    Coherent anti-Stokes Raman scattering (CARS) microspectroscopy has demonstrated significant potential for biological and materials imaging. To date, however, the primary mechanism of disseminating CARS spectroscopic information is through pseudocolor imagery, which explicitly neglects a vast majority of the hyperspectral data. Furthermore, current paradigms in CARS spectral processing do not lend themselves to quantitative sample-to-sample comparability. The primary limitation stems from the need to accurately measure the so-called nonresonant background (NRB) that is used to extract the chemically-sensitive Raman information from the raw spectra. Measurement of the NRB on a pixel-by-pixel basis is a nontrivial task; thus, reference NRB from glass or water are typically utilized, resulting in error between the actual and estimated amplitude and phase. In this manuscript, we present a new methodology for extracting the Raman spectral features that significantly suppresses these errors through phase detrending and scaling. Classic methods of error-correction, such as baseline detrending, are demonstrated to be inaccurate and to simply mask the underlying errors. The theoretical justification is presented by re-developing the theory of phase retrieval via the Kramers-Kronig relation, and we demonstrate that these results are also applicable to maximum entropy method-based phase retrieval. This new error-correction approach is experimentally applied to glycerol spectra and tissue images, demonstrating marked consistency between spectra obtained using different NRB estimates, and between spectra obtained on different instruments. Additionally, in order to facilitate implementation of these approaches, we have made many of the tools described herein available free for download.

  10. Computer Aided Theragnosis Using Quantitative Ultrasound Spectroscopy and Maximum Mean Discrepancy in Locally Advanced Breast Cancer.

    PubMed

    Gangeh, Mehrdad J; Tadayyon, Hadi; Sannachi, Lakshmanan; Sadeghi-Naini, Ali; Tran, William T; Czarnota, Gregory J

    2016-03-01

    A noninvasive computer-aided-theragnosis (CAT) system was developed for the early therapeutic cancer response assessment in patients with locally advanced breast cancer (LABC) treated with neoadjuvant chemotherapy. The proposed CAT system was based on multi-parametric quantitative ultrasound (QUS) spectroscopic methods in conjunction with advanced machine learning techniques. Specifically, a kernel-based metric named maximum mean discrepancy (MMD), a technique for learning from imbalanced data based on random undersampling, and supervised learning were investigated with response-monitoring data from LABC patients. The CAT system was tested on 56 patients using statistical significance tests and leave-one-subject-out classification techniques. Textural features using state-of-the-art local binary patterns (LBP), and gray-scale intensity features were extracted from the spectral parametric maps in the proposed CAT system. The system indicated significant differences in changes between the responding and non-responding patient populations as well as high accuracy, sensitivity, and specificity in discriminating between the two patient groups early after the start of treatment, i.e., on weeks 1 and 4 of several months of treatment. The proposed CAT system achieved an accuracy of 85%, 87%, and 90% on weeks 1, 4 and 8, respectively. The sensitivity and specificity of developed CAT system for the same times was 85%, 95%, 90% and 85%, 85%, 91%, respectively. The proposed CAT system thus establishes a noninvasive framework for monitoring cancer treatment response in tumors using clinical ultrasound imaging in conjunction with machine learning techniques. Such a framework can potentially facilitate the detection of refractory responses in patients to treatment early on during a course of therapy to enable possibly switching to more efficacious treatments. PMID:26529750

  11. Quantitative Antimony Speciation in Shooting-Range Soils by EXAFS Spectroscopy

    SciTech Connect

    Scheinost,A.; Rossberg, A.; Vantelon, D.; Xifra, I.; Kretzschmar, R.; Leuz, A.; Funke, H.; Johnson, C.

    2006-01-01

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

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

    USGS Publications Warehouse

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

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    PubMed Central

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

    2013-01-01

    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

  15. Spatial modulation spectroscopy for imaging and quantitative analysis of single dye-doped organic nanoparticles inside cells

    NASA Astrophysics Data System (ADS)

    Devadas, Mary Sajini; Devkota, Tuphan; Guha, Samit; Shaw, Scott K.; Smith, Bradley D.; Hartland, Gregory V.

    2015-05-01

    Imaging of non-fluorescent nanoparticles in complex biological environments, such as the cell cytosol, is a challenging problem. For metal nanoparticles, Rayleigh scattering methods can be used, but for organic nanoparticles, such as dye-doped polymer beads or lipid nanoparticles, light scattering does not provide good contrast. In this paper, spatial modulation spectroscopy (SMS) is used to image single organic nanoparticles doped with non-fluorescent, near-IR croconaine dye. SMS is a quantitative imaging technique that yields the absolute extinction cross-section of the nanoparticles, which can be used to determine the number of dye molecules per particle. SMS images were recorded for particles within EMT-6 breast cancer cells. The measurements allowed mapping of the nanoparticle location and the amount of dye in a single cell. The results demonstrate how SMS can facilitate efforts to optimize dye-doped nanoparticles for effective photothermal therapy of cancer.Imaging of non-fluorescent nanoparticles in complex biological environments, such as the cell cytosol, is a challenging problem. For metal nanoparticles, Rayleigh scattering methods can be used, but for organic nanoparticles, such as dye-doped polymer beads or lipid nanoparticles, light scattering does not provide good contrast. In this paper, spatial modulation spectroscopy (SMS) is used to image single organic nanoparticles doped with non-fluorescent, near-IR croconaine dye. SMS is a quantitative imaging technique that yields the absolute extinction cross-section of the nanoparticles, which can be used to determine the number of dye molecules per particle. SMS images were recorded for particles within EMT-6 breast cancer cells. The measurements allowed mapping of the nanoparticle location and the amount of dye in a single cell. The results demonstrate how SMS can facilitate efforts to optimize dye-doped nanoparticles for effective photothermal therapy of cancer. Electronic supplementary information (ESI) available: TEM imaging, calibration experiments for the SMS instrument with gold nanoparticles, SMS images of dye doped polymer beads from a commercial source, evidence for endosome uptake, and additional SMS images of dye-doped LPNPs in EMT-6 cells, and spectra of SRfluor680/croconaine doped lipid-polymer nanoparticles. See DOI: 10.1039/C5NR01614B

  16. [Research on the Quantitative Analysis for In-Situ Detection of Acid Radical Ions Using Laser Raman Spectroscopy].

    PubMed

    Chen, Jing; Li, Ying; Du, Zeng-feng; Gu, Yan-hong; Guo, Jin-jia

    2015-09-01

    Laser Raman spectroscopy as an in situ analytical technology can enable detailed investigation of the ocean environment. It is necessary to set up a quantitative analysis method based on laser Raman spectroscopy to understand the marine status in situ. In the laboratory investigations, varied concentration of HCO3(-), SO4(2-) and coastal waters of Qingdao are taken as the samples, operating 532 nm of laser, using fiber optic probes to simulate detection mode in situ. Raman spectra are analyzed using the method of internal standard normalization, multiple linear regression (MLR), general Partial Least Squares (PLS) and PLS based on dominant factor respectively in data processing. It was found that correlation coefficients of calibration curves are not high in internal standard normalization method and predicted relative errors on the prepared samples are much high, so internal standard normalization method cannot be effectively used in the quantitative analysis of HCO3(-), SO4(2-) in the water. And with the multiple linear regression, the analysis accuracy was improved effectively. The calibration curve of PLS based on dominant factor showed that the SO4(2-) and HCO3(-) of pre-made solution with correlation coefficient R2 of 0.990 and 0.916 respectively. The 30 mmol · L(-1) of SO4(2-) and 20 mmol · L(-1) of HCO3(-) in two target samples were determined with the relative errors lower than 3.262% and 5.267% respectively. SO4(2-) in the coastal waters as the research object was analyzed by above-mentioned methods, comparing with 28.01 mmol · L(-1) by ion chromatography. It was demonstrated that PLS based on dominant factor method is superior to the rest of the three analysis methods, which can be used in situ calibration, with the mean relative error about 1.128%. All the results show that analysis accuracy would be improved by the PLS based on dominant factor method to predict concentration of acid radical ions. PMID:26669165

  17. Quantitative analysis of chromium in potatoes by laser-induced breakdown spectroscopy coupled with linear multivariate calibration.

    PubMed

    Chen, Tianbing; Huang, Lin; Yao, Mingyin; Hu, Huiqin; Wang, Caihong; Liu, Muhua

    2015-09-01

    Laser-induced breakdown spectroscopy (LIBS) coupled with the linear multivariate regression method was utilized to analyze chromium (Cr) quantitatively in potatoes. The plasma was generated using a Nd:YAG laser, and the spectra were acquired by an Andor spectrometer integrated with an ICCD detector. The models between intensity of LIBS characteristic line(s) and concentration of Cr were constructed to predict quantitatively the content of target. The unary, binary, ternary, and quaternary variables were chosen for verifying the accuracy of linear regression calibration curves. The intensity of characteristic lines Cr (CrI: 425.43, 427.48, 428.97nm) and Ca (CaI: 422.67, 428.30, 430.25, 430.77, 431.86nm) were used as input data for the multivariate calculations. According to the results of linear regression, the model of quaternary linear regression was established better in comparing with the other three models. A good agreement was observed between the actual content provided by atomic absorption spectrometry and the predicted value obtained by the quaternary linear regression model. And the relative error was below 5.5% for validation samples S1 and S2. The result showed that the multivariate approach can obtain better predicted accuracy than the univariate ones. The result also suggested that the LIBS technique coupled with the linear multivariate calibration method could be a great tool to predict heavy metals in farm products in a rapid manner even though samples have similar elemental compositions. PMID:26368908

  18. Quantitative Subtractively Normalized Interfacial Fourier Transform Infrared Reflection Spectroscopy Study of the Adsorption of Adenine on Au(111) Electrodes.

    PubMed

    Prieto, Francisco; Su, Zhangfei; Leitch, J Jay; Rueda, Manuela; Lipkowski, Jacek

    2016-04-26

    Quantitative subtractively normalized interfacial Fourier transform infrared reflection spectroscopy (SNIFTIRS) was used to determine the molecular orientation and identify the metal-molecular interactions responsible for the adsorption of adenine from the bulk electrolyte solution onto the surface of the Au(111) electrode. The recorded p-polarized IR spectra of the adsorbed species were subtracted from the collected s-polarized IR spectra to remove the IR contributions of the vibrational bands of the desorbed molecules that are located within the thin layer cavity of the spectroelectrochemical cell. The intense IR band around 1640 cm(-1), which is assigned to the pyrimidine ring stretching vibrations of the C5-C6 and C6-N10 bonds, and the IR band at 1380 cm(-1), which results from a combination of the ring stretching vibration of the C5-C7 bond and the in-plane CH bending vibration, were selected for the quantitative analysis measurements. The transition dipoles of these bands were evaluated by DFT calculations. Their orientations differed by 85 ± 5°. The tilt angles of adsorbed adenine molecules were calculated from the intensity of these two vibrations at different potentials. The results indicate that the molecular plane is tilted at an angle of 40° with respect to the surface normal of the electrode and rotates by 16° around its normal axis with increasing electrode potential. This orientation results from the chemical interaction between the N10 and gold atoms coupled with the π-π parallel stacking interactions between the adjacent adsorbed molecules. Furthermore, the changes in the molecular plane rotation with the electric field suggests that the N1 atom of adenine must also participate in the interaction between the molecule and metal. PMID:27040121

  19. Third order nonlinear optical susceptibility of fluorescein-containing polymers determined by electro-absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Gomez-Sosa, Gustavo; Beristain, Miriam F.; Ortega, Alejandra; Martínez-Viramontes, Jaquelin; Ogawa, Takeshi; Fernández-Hernández, Roberto C.; Tamayo-Rivera, Lis; Reyes-Esqueda, Jorge-Alejandro; Isoshima, Takashi; Hara, Masahiko

    2012-03-01

    Novel polymers containing xanthene groups with high dye concentrations were prepared, and their third order nonlinear optical properties were studied by electroabsorption spectroscopy technique. The polymers were amorphous with refractive indices above 1.6 in the non-resonant region. The UV-Visible absorption spectra indicate the fluoresceins molecules in the polymers are H-aggregated. They showed third order nonlinear susceptibility, χ(3) (-ω:ω, 0, 0), of 2.5-3.5 × 10-12 esu.

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed

    2014-10-01

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

  2. Remote quantitative analysis of minerals based on multispectral line-calibrated laser-induced breakdown spectroscopy (LIBS).

    PubMed

    Wan, Xiong; Wang, Peng

    2014-01-01

    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

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

    SciTech Connect

    Clapper-Gowdy, M.; Demirgian, J.; Lang, K.; Robaittaille, G.

    1992-09-01

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

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

    SciTech Connect

    Clapper-Gowdy, M.; Demirgian, J. ); Lang, K.; Robaittaille, G. )

    1992-01-01

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

  5. Use of fluorescence spectroscopy for quantitative investigations of ubiquitin interactions with the ubiquitin-binding domains of NEMO.

    PubMed

    Dubosclard, Virginie; Fontan, Elisabeth; Agou, Fabrice

    2015-01-01

    Ubiquitin serves as a signal for a variety of cellular processes and its specific interaction with ubiquitin-binding domain (UBD) regulates key cellular events including protein degradation, cell-cycle control, DNA repair, and kinase activation. Several binding mechanisms for isolated UBDs have been reported in recent years. However, little is known about the mechanism through which proteins containing multiple-UBDs achieve specificity for a particular oligomer of polyUb. The NF-κB essential modulator (NEMO, also known IKKγ), which plays a key role in the NF-κB signaling pathway, belongs to the latter family of proteins since it contains two distal NOA (also known UBAN/CC2-LZ/NUB) and ZF UBDs, separated by an unstructured proline-rich linker of about 40 residues in length. Here, we show a new procedure for fast purification of this bipartite domain. We also describe the use of intrinsic fluorescence spectroscopy for quantitative investigations of ubiquitin interactions between two distal ubiquitin-binding domains of NEMO (NOA and ZF). This spectroscopic method has many advantages over other techniques like GST pulldown and Biacore's SPR for monitoring avid interactions between two UBDs, especially when UBDs are located at significant distance from each other within the protein. PMID:25736758

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

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    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.

  7. Quantitative sampling of conformational heterogeneity of a DNA hairpin using molecular dynamics simulations and ultrafast fluorescence spectroscopy

    PubMed Central

    Voltz, Karine; Léonard, Jérémie; Touceda, Patricia Tourón; Conyard, Jamie; Chaker, Ziyad; Dejaegere, Annick; Godet, Julien; Mély, Yves; Haacke, Stefan; Stote, Roland H.

    2016-01-01

    Molecular dynamics (MD) simulations and time resolved fluorescence (TRF) spectroscopy were combined to quantitatively describe the conformational landscape of the DNA primary binding sequence (PBS) of the HIV-1 genome, a short hairpin targeted by retroviral nucleocapsid proteins implicated in the viral reverse transcription. Three 2-aminopurine (2AP) labeled PBS constructs were studied. For each variant, the complete distribution of fluorescence lifetimes covering 5 orders of magnitude in timescale was measured and the populations of conformers experimentally observed to undergo static quenching were quantified. A binary quantification permitted the comparison of populations from experimental lifetime amplitudes to populations of aromatically stacked 2AP conformers obtained from simulation. Both populations agreed well, supporting the general assumption that quenching of 2AP fluorescence results from pi-stacking interactions with neighboring nucleobases and demonstrating the success of the proposed methodology for the combined analysis of TRF and MD data. Cluster analysis of the latter further identified predominant conformations that were consistent with the fluorescence decay times and amplitudes, providing a structure-based rationalization for the wide range of fluorescence lifetimes. Finally, the simulations provided evidence of local structural perturbations induced by 2AP. The approach presented is a general tool to investigate fine structural heterogeneity in nucleic acid and nucleoprotein assemblies. PMID:26896800

  8. Protein analysis by 31p NMR spectroscopy in ionic liquid: quantitative determination of enzymatically created cross-links.

    PubMed

    Monogioudi, Evanthia; Permi, Perttu; Filpponen, Ilari; Lienemann, Michael; Li, Bin; Argyropoulos, Dimitris; Buchert, Johanna; Mattinen, Maija-Liisa

    2011-02-23

    Cross-linking of β-casein by Trichoderma reesei tyrosinase (TrTyr) and Streptoverticillium mobaraense transglutaminase (Tgase) was analyzed by (31)P nuclear magnetic resonance (NMR) spectroscopy in ionic liquid (IL). According to (31)P NMR, 91% of the tyrosine side chains were cross-linked by TrTyr at high dosages. When Tgase was used, no changes were observed because a different cross-linking mechanism was operational. However, this verified the success of the phosphitylation of phenolics within the protein matrix in the IL. Atomic force microscopy (AFM) in solid state showed that disk-shaped nanoparticles were formed in the reactions with average diameters of 80 and 20 nm for TrTyr and Tgase, respectively. These data further advance the current understanding of the action of tyrosinases on proteins on molecular and chemical bond levels. Quantitative (31)P NMR in IL was shown to be a simple and efficient method for the study of protein modification. PMID:21218836

  9. In Situ Determination of Fructose Isomer Concentrations in Wine Using (13)C Quantitative Nuclear Magnetic Resonance Spectroscopy.

    PubMed

    Colombo, Cinzia; Aupic, Clara; Lewis, Andrew R; Pinto, B Mario

    2015-09-30

    A practical method for simultaneously quantifying fructose and ethanol contents in wines using (13)C quantitative nuclear magnetic resonance (qNMR) spectroscopy is reported. Less than 0.6 mL of wine is needed, and the method leaves an unmodified sample available for subsequent testing or additional analyses. The relative ratios of the five known fructose isomers in ethanolic solutions at different pH and their variations with the temperature are also reported. The data are correlated with the sweetness of wines. The technique was applied to commercially available wines, and the results are compared to other methods. Sugar levels above 0.6 g/L can also be measured. A simple adaptation of the method permits measurement of different carbohydrates using integration of single peaks for each compound, in combination with an external reference (13)C qNMR spectrum of a sample with a known concentration. The method can be applied at all stages of wine production, including grape must, during fermentation, and before and after bottling. PMID:26350157

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

    PubMed

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

    1995-02-20

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

  11. Quantitative sampling of conformational heterogeneity of a DNA hairpin using molecular dynamics simulations and ultrafast fluorescence spectroscopy.

    PubMed

    Voltz, Karine; Léonard, Jérémie; Touceda, Patricia Tourón; Conyard, Jamie; Chaker, Ziyad; Dejaegere, Annick; Godet, Julien; Mély, Yves; Haacke, Stefan; Stote, Roland H

    2016-04-20

    Molecular dynamics (MD) simulations and time resolved fluorescence (TRF) spectroscopy were combined to quantitatively describe the conformational landscape of the DNA primary binding sequence (PBS) of the HIV-1 genome, a short hairpin targeted by retroviral nucleocapsid proteins implicated in the viral reverse transcription. Three 2-aminopurine (2AP) labeled PBS constructs were studied. For each variant, the complete distribution of fluorescence lifetimes covering 5 orders of magnitude in timescale was measured and the populations of conformers experimentally observed to undergo static quenching were quantified. A binary quantification permitted the comparison of populations from experimental lifetime amplitudes to populations of aromatically stacked 2AP conformers obtained from simulation. Both populations agreed well, supporting the general assumption that quenching of 2AP fluorescence results from pi-stacking interactions with neighboring nucleobases and demonstrating the success of the proposed methodology for the combined analysis of TRF and MD data. Cluster analysis of the latter further identified predominant conformations that were consistent with the fluorescence decay times and amplitudes, providing a structure-based rationalization for the wide range of fluorescence lifetimes. Finally, the simulations provided evidence of local structural perturbations induced by 2AP. The approach presented is a general tool to investigate fine structural heterogeneity in nucleic acid and nucleoprotein assemblies. PMID:26896800

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

    PubMed

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

    2012-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Klasing, Manfred; Zange, Jochen

    2003-10-01

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

  14. Quantitative investigation of compartmentalized dynamics of ErbB2 targeting gold nanorods in live cells by single molecule spectroscopy.

    PubMed

    Chen, Jiji; Irudayaraj, Joseph

    2009-12-22

    Understanding the diffusion dynamics and receptor uptake mechanism of nanoparticles in cancer cells is crucial to the rational design of multifunctional nanoprobes for targeting and delivery. In this report, for the first time, we quantify the localization and evaluate the diffusion times of Herceptin-conjugated gold nanorods (H-GNRs) in different cell organelles by fluorescence correlation spectroscopy (FCS) and examine the endocytic diffusion of H-GNRs in live ErbB2 overexpressing SK-BR-3 cells. First, by colocalizing H-GNRs in different cellular organelles depicted by the respective markers, we demonstrate that H-GNRs colocalize with the endosome and lysosome but not with the Golgi apparatus. Our study shows that Herceptin-conjugated GNRs have similar intracellular localization characteristics as Herceptin-ErbB2 complex, with a higher concentration found in the endosome (72 +/- 20.6 nM) than lysosome (9.4 +/- 4.2 nM) after internalization. The demonstrated approach and findings not only lay the foundations for a quantitative understanding of the fate of nanoparticle-based targeting but also provide new insights into the rational design of nanoparticle delivery systems for effective treatment. PMID:19891423

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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.

  16. Disulfide-Linked Dinitroxides for Monitoring Cellular Thiol Redox Status through Electron Paramagnetic Resonance Spectroscopy.

    PubMed

    Legenzov, Eric A; Sims, Stephen J; Dirda, Nathaniel D A; Rosen, Gerald M; Kao, Joseph P Y

    2015-12-01

    Intracellular thiol-disulfide redox balance is crucial to cell health, and may be a key determinant of a cancer's response to chemotherapy and radiation therapy. The ability to assess intracellular thiol-disulfide balance may thus be useful not only in predicting responsiveness of cancers to therapy, but in assessing predisposition to disease. Assays of thiols in biology have relied on colorimetry or fluorimetry, both of which require UV-visible photons, which do not penetrate the body. Low-frequency electron paramagnetic resonance imaging (EPRI) is an emerging magnetic imaging technique that uses radio waves, which penetrate the body well. Therefore, in combination with tailored imaging agents, EPRI affords the opportunity to image physiology within the body. In this study, we have prepared water-soluble and membrane-permeant disulfide-linked dinitroxides, at natural isotopic abundance, and with D,(15)N-substitution. Thiols such as glutathione cleave the disulfides, with simple bimolecular kinetics, to yield the monomeric nitroxide species, with distinctive changes in the EPR spectrum. Using the D,(15)N-substituted disulfide-dinitroxide and EPR spectroscopy, we have obtained quantitative estimates of accessible intracellular thiol in cultured human lymphocytes. Our estimates are in good agreement with published measurements. This suggests that in vivo EPRI of thiol-disulfide balance is feasible. Finally, we discuss the constraints on the design of probe molecules that would be useful for in vivo EPRI of thiol redox status. PMID:26523485

  17. Developments in laser-induced fluorescence spectroscopy for quantitative in situ measurements of free radicals in the troposphere

    NASA Astrophysics Data System (ADS)

    Heard, Dwayne

    2015-04-01

    Photo-oxidation in the troposphere is highly complex, being initiated by short lived free radical species, in the daytime dominated by the hydroxyl radical, OH. Chemical oxidation cycles, which also involve peroxy radicals (HO2 and RO2), remove natural or anthropogenic emissions (for example methane) and generate a range of secondary products, for example ozone, nitrogen dioxide, acidic and multifunctional organic species, and secondary organic aerosol, which impact on human health and climate. Owing to their short lifetime in the atmosphere, the abundance of radicals is determined solely by their rate of chemical production and loss, and not by transport. Field measurements of the concentrations of radicals and comparison with calculations using a numerical model therefore constitutes one of the very best ways to test whether the chemistry in each of these locations is understood and accurately represented in the model. Validation of the chemistry is important, as the predictions of climate and air quality models containing this chemistry are used to drive the formulation of policy and legislation. However, in situ measurements of radical species, owing to their very low abundance (often sub part per trillion) and short lifetimes (< 1 second for OH), remain extremely challenging. Laser-induced fluorescence spectroscopy (LIF) has enjoyed considerable success worldwide for the quantitative detection of radicals in a range of environments. The radicals are either excited directly by the laser (e.g. OH, IO) or are first chemically converted to OH prior to detection (e.g. HO2, RO2). Recent developments in the LIF technique for radical detection, which uses a supersonic expansion with detection at low pressure and multi kHz pulse repetition rate tunable laser systems, will be discussed, together with calibration methods to make signals absolute, and identification of potential interferences. LIF instruments have been operated on ground, ship and aircraft platforms at a number of locations worldwide, and examples from recent fieldwork involving the Leeds instruments will be presented.

  18. Rapid and quantitative detection of the microbial spoilage of meat by fourier transform infrared spectroscopy and machine learning.

    PubMed

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

    2002-06-01

    Fourier transform infrared (FT-IR) spectroscopy is a rapid, noninvasive technique with considerable potential for application in the food and related industries. We show here that this technique can be used directly on the surface of food to produce biochemically interpretable "fingerprints." Spoilage in meat is the result of decomposition and the formation of metabolites caused by the growth and enzymatic activity of microorganisms. FT-IR was exploited to measure biochemical changes within the meat substrate, enhancing and accelerating the detection of microbial spoilage. Chicken breasts were purchased from a national retailer, comminuted for 10 s, and left to spoil at room temperature for 24 h. Every hour, FT-IR measurements were taken directly from the meat surface using attenuated total reflectance, and the total viable counts were obtained by classical plating methods. Quantitative interpretation of FT-IR spectra was possible using partial least-squares regression and allowed accurate estimates of bacterial loads to be calculated directly from the meat surface in 60 s. Genetic programming was used to derive rules showing that at levels of 10(7) bacteria.g(-1) the main biochemical indicator of spoilage was the onset of proteolysis. Thus, using FT-IR we were able to acquire a metabolic snapshot and quantify, noninvasively, the microbial loads of food samples accurately and rapidly in 60 s, directly from the sample surface. We believe this approach will aid in the Hazard Analysis Critical Control Point process for the assessment of the microbiological safety of food at the production, processing, manufacturing, packaging, and storage levels. PMID:12039738

  19. Discrimination of white matter lesions and multiple sclerosis plaques by short echo quantitative 1H-magnetic resonance spectroscopy.

    PubMed

    Kapeller, P; Ropele, S; Enzinger, C; Lahousen, T; Strasser-Fuchs, S; Schmidt, R; Fazekas, F

    2005-10-01

    Multiple sclerosis (MS) plaques and age related white matter lesions (WML) are of similar morphological appearance on T2 weighted MRI. Therefore their differentiation is sometimes crucial. Proton magnetic resonance spectroscopy ((1)H-MRS) adds metabolic information to conventional imaging and may help to distinguish inflammatory MS plaques from vascular related WML. This study was performed to evaluate the metabolite pattern in MS plaques and WML. 15 MS patients, 14 elderly individuals with WML and 16 controls were investigated by conventional MRI and short echo quantitative (1)H-MRS (TE: 30ms, TR: 3000ms). The mean metabolite concentrations in normal control white matter (NCWM), MS plaques and WML were: t-NAA: 8.96 mmol/l (SD: 0.93) vs 6.79 mmol/l (SD: 1.99) vs 7.18 mmol/l (SD: 1.41); Cho:1.66 mmol/l (SD: 0.4) vs 1.49 mmol/l (SD: 0.45) vs 1.46 mmol/l (SD: 0.34); PCr:5.64 mmol/l (SD: 0.83) vs 4.9mmol/l (SD: 1.3) vs 4.95 mmol/l (SD: 0.86); myo-Ins: 4.57 mmol/l (SD:1.05) vs 6.34 mmol/l (SD: 2.03) vs 4.5 mmol/l (SD: 0.96). t-NAA reduction in MS plaques and WML was significant compared with controls (p

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

    PubMed

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

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    We have developed quantitative Raman spectroscopic techniques for the novel detection of dissolved species in sea water to determine their fundamental properties. In this example we use a field-deployable Raman system to determine the solubility of 1,4-thioxane (TO) in sea water as 0.65 to 0.63 mol/kg H2O between 4.5°C and 25.0°C (which varies greatly from an earlier report of 2.75 mol/kg H2O), and to assess the conditions under which it may form a hydrate. TO is of unusual environmental interest as a breakdown product of the chemical weapon mustard gas, and thus development of non-contact field- deployable sensing techniques is highly desirable. Raman spectroscopy has typically been considered as only a qualitative technique due to the complexity of the optical path and the substantial changes in components between different instruments. We show here that by self-referencing to the ubiquitous water peaks (the water ν2 mode from 1500 to 1800 cm-1) we can derive quantitative information with a precision of ± 4%, and provide essential new information. The long-term fate of large quantities of chemical weapons disposed of in the ocean some 50 years ago is poorly known. Part of this lacking knowledge can be attributed to the hazards associated with the direct study of these materials leaving ocean scientists vulnerable when sampling in inadequately marked sites. Mustard gas (1,1'-thiobis[2-chloroethane]) represents the largest tonnage of material disposed of until the 1972 London Convention banned such activities. Thus there is strong interest in determining the fate and lifetime of these materials, their decomposition products, and the extent of the affected zones. We have earlier shown that TO forms a hydrate with a help-gas, such as methane or hydrogen sulfide, and that the temperature, pressure and reducing conditions required for hydrate formation commonly occur at known disposal sites. In fact, a mixed TO hydrate is more stable than methane hydrate by almost 10°C. Here we show that in the presence of hydrate formation, as with other hydrate guest molecules, the TO solubility trend was reversed and solubility decreased in response to lower temperatures. The relatively low solubility in water coupled with the ability to form a hydrate within marine sediments can greatly decrease molecular mobility and increase chemical lifetime. Mixing will reduce concentrations of TO in the ocean water column below the detection limits established here. But the solubility data reveals the concentrations that will characterize marine pore waters at such sites, and these are readily detectable. Development of pore water Raman sensing techniques are underway.

  2. Nuclear magnetic resonance spectroscopy as a quantitative tool to determine the concentrations of biologically produced metabolites: implications in metabolites in safety testing.

    PubMed

    Espina, Robert; Yu, Linning; Wang, Jianyao; Tong, Zeen; Vashishtha, Sarvesh; Talaat, Rasmy; Scatina, JoAnn; Mutlib, Abdul

    2009-02-01

    Nuclear magnetic resonance (NMR) spectroscopy has traditionally been considered as an indispensable tool in elucidating structures of metabolites. With the advent of Fourier transform (FT) spectrometers, along with improvements in software and hardware (such as high-field magnets, cryoprobes, versatile pulse sequences, and solvent suppression techniques), NMR is increasingly being considered as a critical quantitative tool, despite its lower sensitivity as compared to mass spectrometry. A specific quantitative application of NMR is in determining the concentrations of biologically isolated metabolites, which could potentially be used as reference standards for further quantitative work by liquid chromatography/mass spectrometry. With the recent demands from regulatory agencies on quantitative information on metabolites, it is proposed that NMR will play a significant role in strategies aimed at addressing metabolite coverage in toxicological species. Traditionally, biologically isolated metabolites have not been considered as a way of generating "reference standards" for further quantitative work. However, because of the recent FDA guidance on safety testing of metabolites, one has to consider means of authenticating and quantitating biologically or nonbiologically generated metabolites. 1H NMR is being proposed as the method of choice, as it is able to be used as both a qualitative and a quantitative tool, hence allowing structure determination, purity check, and quantitative measurement of the isolated metabolite. In this publication, the application of NMR as a powerful and robust analytical technique in determining the concentrations of in vitro or in vivo isolated metabolites is discussed. Furthermore, to demonstrate the reliability and accuracy of metabolite concentrations determined by NMR, validation and cross-validation with gravimetric and mass spectrometric methods were conducted. PMID:18980340

  3. High-Throughput Near-Infrared Reflectance Spectroscopy for Predicting Quantitative and Qualitative Composition Phenotypes of Individual Maize Kernels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near-infrared reflectance (NIR) spectroscopy can be used for fast and reliable prediction of organic compounds in complex biological samples. We used a recently developed NIR spectroscopy instrument to predict starch, protein, oil, and weight of individual maize (Zea mays) seeds. The starch, prote...

  4. Screening spectroscopy of prostate cancer

    NASA Astrophysics Data System (ADS)

    Yermolenko, S. B.; Voloshynskyy, D. I.; Fedoruk, O. S.

    2015-11-01

    The aim of the study was to establish objective parameters of the field of laser and incoherent radiation of different spectral ranges (UV, visible, IR) as a non-invasive optical method of interaction with different samples of biological tissues and fluids of patients to determine the state of prostate cancer and choosing the best personal treatment. The objects of study were selected venous blood plasma of patient with prostate cancer, histological sections of rat prostate gland in the postoperative period. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5-25 microns) dry residue of plasma by spectral diagnostic technique of thin histological sections of biological tissues.

  5. 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...

  6. Top-hat cw-laser-induced time-resolved mode-mismatched thermal lens spectroscopy for quantitative analysis of low-absorption materials.

    PubMed

    Astrath, Nelson G C; Astrath, Francine B G; Shen, Jun; Zhou, Jianqin; Pedreira, Paulo R B; Malacarne, Luis C; Bento, Antonio C; Baesso, Mauro L

    2008-07-01

    Thermal lens spectroscopy is a highly sensitive and versatile photothermal technique for material analysis, providing optical and thermal properties. To use less expensive multimode non-Gaussian lasers for quantitative analysis of low-absorption materials, this Letter presents a theoretical model for time-resolved mode-mismatched thermal lens spectroscopy induced by a cw laser with a top-hat profile. The temperature profile in a sample was calculated, and the intensity of the probe beam center at the detector plane was also derived using the Fresnel diffraction theory. Experimental validation was performed with glass samples, and the results were found well consistent with literature values of the thermo-optical properties of the samples. PMID:18594666

  7. Application of the quantitative detection of a change in concentration of magnesium stearate in a feeder tube of tableting manufacture by real-time near-infrared spectroscopy.

    PubMed

    Sasakura, D; Nakayama, K; Chikuma, T

    2015-10-01

    Process analytical technology is important for the analysis and control of manufacturing processes. Near-infrared spectroscopy is widely used in various process analytical technologies for the analysis of the chemical componentsof solid dosage forms. Lubrication is an important process carried out before a tablet is produced. In this process, the concentration of lubricant, such as magnesium stearate (StMg), might change for one of many reasons during powder transport, which would be a critical problem such as variation in tablet compressibility and dissolution failure of compressed tablets. Our group investigated the feasibility of the quantitative monitoring of a change in the concentration of StMg in the feeder tube of tableting equipment employing real-time near-infrared spectroscopy. PMID:26601418

  8. X-Ray Absorption Correction for Quantitative Scanning Transmission Electron Microscopic Energy-Dispersive X-Ray Spectroscopy of Spherical Nanoparticles.

    PubMed

    Slater, Thomas; Chen, Yiqiang; Auton, Gregory; Zaluzec, Nestor; Haigh, Sarah

    2016-04-01

    A new method to perform X-ray absorption correction for spherical particles in quantitative energy-dispersive X-ray spectroscopy in the scanning transmission electron microscope is presented. An absorption correction factor is derived and simulated data is presented encompassing a range of X-ray absorption conditions. Theoretical calculations are compared with experimental data of X-ray counts from Au nanoparticles to verify the derived methodology. The effect of detector elevation angle is considered and a comparison with thin-film absorption correction is included. PMID:27050041

  9. Quantitative measurement of Au and Fe in ferromagnetic nanoparticles with Laser Induced Breakdown Spectroscopy using a polymer-based gel matrix

    NASA Astrophysics Data System (ADS)

    Borowik, T.; Przybyło, M.; Pala, K.; Otlewski, J.; Langner, M.

    2011-09-01

    The medical applications of nanomaterials require substantial changes in the research and development stage, such as the introduction of new processes and methods, and adequate modifications of the national and international laws on the medical product registration. To accomplish this, proper parameterizations of nano-scaled products need to be developed and implemented, accompanied by suitable measuring methods. The introduction of metallic particles to medical practices requires the precise, quantitative evaluation of the production process and later quantification and characterization of the nanoparticles in biological matrices for the bioavailability and biodistribution evaluation. In order to address these issues we propose a method for the quantitative analysis of the metallic nanoparticles composition by Laser Induced Breakdown Spectroscopy (LIBS). Au/Fe ferro-magnetic nanoparticles were used to evaluate the method applicability. Since the powder form of nanoparticles spatters upon laser ablation, first we had to develop fast, convenient and quantitative method for the nano-powdered sample preparation. The proposed method is based on the polymer gelation of nanopowders or their water suspensions. It has been shown that nanopowders compositional changes throughout the production process, along with their final characterization, can be reliable performed with LIBS technique. The quantitative values obtained were successfully correlated with those derived with ICP technique.

  10. Quantitative Intracavity Laser Spectroscopy Measurements with a Ti:sapphire Laser: Absorption Intensities for Water Vapor Lines in the 790-800 nm Region.

    PubMed

    Kalmar; O'brien

    1998-12-01

    The intracavity laser spectroscopy (ILS) technique has been shown to be a very sensitive method for observing absorption spectra. By considering quantitative results (line-strengths and pressure broadening coefficients) obtained using the ILS method with a dye laser, the technique has been shown to provide quantitative information that is in excellent agreement with the values afforded by use of more traditional methods for acquiring absorption spectra. A similar investigation has been conducted for an ILS system based on a Ti:sapphire laser. Presented here are quantitative results for water vapor transitions occurring around 795 nm. Line intensities are determined as a function of water vapor pressure and effective path length (i.e., generation time). The line-strengths are compared with values determined by R. A. Toth [J. Mol. Spectrosc. 166, 176-183 (1994)] who used a multipass cell and the Fourier transform spectrometer at the Kitt Peak National Observatory. The good agreement between the results demonstrates that quantitatively accurate data can be obtained using the ILS technique with a Ti:sapphire laser. Copyright 1998 Academic Press. PMID:9831505

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

    SciTech Connect

    Reich, F.R.

    1997-08-11

    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.

  12. Alternate strategies to obtain mass balance without the use of radiolabeled compounds: application of quantitative fluorine (19F) nuclear magnetic resonance (NMR) spectroscopy in metabolism studies.

    PubMed

    Mutlib, Abdul; Espina, Robert; Atherton, James; Wang, Jianyao; Talaat, Rasmy; Scatina, JoAnn; Chandrasekaran, Appavu

    2012-03-19

    Nuclear magnetic resonance (NMR) spectroscopy is playing an increasingly important role in the quantitation of small and large molecules. Recently, we demonstrated that (1)H NMR could be used to quantitate drug metabolites isolated in submilligram quantities from biological sources. It was shown that these metabolites, once quantitated by NMR, were suitable to be used as reference standards in quantitative LC/MS-based assays, hence circumventing the need for radiolabeled material or synthetic standards to obtain plasma exposure estimates in humans and preclinical species. The quantitative capabilities of high-field NMR is further demonstrated in the current study by obtaining the mass balance of fluorinated compounds using (19)F-NMR. Two fluorinated compounds which were radio-labeled with carbon-14 on metabolically stable positions were dosed in rats and urine and feces collected. The mass balance of the compounds was obtained initially by counting the radioactivity present in each sample. Subsequently, the same sets of samples were analyzed by (19)F-NMR, and the concentrations determined by this method were compared with data obtained using radioactivity counting. It was shown that the two methods produced comparable values. To demonstrate the value of this analytical technique in drug discovery, a fluorinated compound was dosed intravenously in dogs and feces and urine collected. Initial profiling of samples showed that this compound was excreted mainly unchanged in feces, and hence, an estimate of mass balance was obtained using (19)F-NMR. The data obtained by this method was confirmed by additional quantitative studies using mass spectrometry. Hence cross-validations of the quantitative (19)F-NMR method by radioactivity counting and mass spectrometric analysis were demonstrated in this study. A strategy outlining the use of fluorinated compounds in conjunction with (19)F-NMR to understand their routes of excretion or mass balance in animals is proposed. These studies demonstrate that quantitative (19)F-NMR could be used as an alternate technique to obtain an estimate of the mass balance of fluorinated compounds, especially in early drug development where attrition of the compounds is high, and cost savings could be realized through the use of such a technique rather than employing radioactive compounds. The potential application of qNMR in conducting early human ADME studies with fluorinated compounds is also discussed. PMID:22292524

  13. Quantitative Analysis of Salidroside and p-Tyrosol in the Traditional Tibetan Medicine Rhodiola crenulata by Fourier Transform Near-Infrared Spectroscopy.

    PubMed

    Li, Tao; He, Xuan

    2016-01-01

    A nondestructive, efficient, and rapid method for quantitative analysis of two bioactive components (salidroside and p-tyrosol) in Rhodiola crenulata, a traditional Tibetan medicine, by Fourier transform near-infrared (FT-NIR) spectroscopy was developed. Near-infrared diffuse reflectance spectra in the range of 4000 to 10000 cm(-1) of 50 samples of Rhodiola crenulata with different sources were measured. To get a satisfying result, partial least squares regression (PLSR) was used to establish NIR models for salidroside and p-tyrosol content determination. Different preprocessing methods, including smoothing, taking a second derivative, standard normal variate (SNV) transformation, and multiplicative scatter correction (MSC), were investigated to improve the model accuracy of PLSR. The performance of the two final models (salidroside model and p-tyrosol model) was evaluated by factors such as the values of correlation coefficient (R(2)), root mean square error of prediction (RMSEP), and root mean square error of calibration (RMSEC). The optimal results of the PLSR model of salidroside showed that R(2), RMSEP and RMSEC were 0.99572, 0.0294 and 0.0309, respectively. Meanwhile, in the optimization model of p-tyrosol, the R(2), RMSEP and RMSEC were 0.99714, 0.0154 and 0.0168, respectively. These results demonstrate that FT-NIR spectroscopy not only provides a precise, rapid method for quantitative analysis of major effective constituents in Rhodiola crenulata, but can also be applied to the quality control of Rhodiola crenulata. PMID:27039830

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

    ERIC Educational Resources Information Center

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

    2008-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2008-01-01

    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…

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Pefloxacin mesylate, a broad-spectrum antibacterial fluoroquinolone, has been widely used in clinical practice. Therefore, it is very important to detect the concentration of Pefloxacin mesylate. In this research, the near-infrared spectroscopy (NIRS) has been applied to quantitatively analyze on 108 injection samples, which was divided into a calibration set containing 89 samples and a prediction set containing 19 samples randomly. In order to get a satisfying result, partial least square (PLS) regression and principal components regression (PCR) have been utilized to establish quantitative models. Also, the process of establishing the models, parameters of the models, and prediction results were discussed in detail. In the PLS regression, the values of the coefficient of determination ( R2) and root mean square error of cross-validation (RMSECV) of PLS regression are 0.9263 and 0.00119, respectively. For comparison, though applying PCR method to get the values of R2 and RMSECV we obtained are 0.9685 and 0.00108, respectively. And the values of the standard error of prediction set (SEP) of PLS and PCR models are 0.001480 and 0.001140. The result of the prediction set suggests that these two quantitative analysis models have excellent generalization ability and prediction precision. However, for this PFLX injection samples, the PCR quantitative analysis model achieved more accurate results than the PLS model. The experimental results showed that NIRS together with PCR method provide rapid and accurate quantitative analysis of PFLX injection samples. Moreover, this study supplied technical support for the further analysis of other injection samples in pharmaceuticals.

  17. 1H HR-MAS Spectroscopy for Quantitative Measurement of Choline Concentration in Amniotic Fluid as a Marker of Fetal Lung Maturity: Inter-and Intraobserver Reproducibility Study

    PubMed Central

    Joe, Bonnie N.; Vahidi, Kiarash; Zektzer, Andrew; Chen, Mei-Hsiu; Clifton, Matthew S.; Butler, Thomas; Keshari, Kayvan; Kurhanewicz, John; Coakley, Fergus; Swanson, Mark G.

    2016-01-01

    Purpose To determine the intra- and interobserver reproducibility of human amniotic fluid metabolite concentration measurements (including potential markers of fetal lung maturity) detectable by MR spectroscopy. Materials and Methods 1H high-resolution magic angle spinning (HR-MAS) spectroscopy was performed at 11.7T on 23 third-trimester amniotic fluid samples. Samples were analyzed quantitatively using 3-(trimethylsilyl)propionic-2,2,3,3-d4 acid (TSP) as a reference. Four observers independently quantified eight metabolite regions (TSP, lactate doublet and quartet, alanine, citrate, creatinine, choline, and glucose) twice from anonymized, randomized spectra using a semiautomated software program. Results Excellent inter- and intraobserver reproducibility was found for all metabolites. Intraclass correlation as a measure of interobserver agreement for the four readers ranged from 0.654 to 0.995. A high correlation of 0.973 was seen for choline in particular, a major component of surfactant. Pearson correlation as a measure of intraobserver reproducibility ranged from 0.478 to 0.999. Conclusion Quantification of choline and other metabolite concentrations in amniotic fluid by high-resolution MR spectroscopy can be performed with high inter- and intraobserver reproducibility. Demonstration of reproducible metabolite concentration measurements is a critical first step in the search for biomarkers of fetal lung maturity. PMID:19025962

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

    SciTech Connect

    Unnikrishnan, V. K.; Nayak, Rajesh; Kartha, V. B.; Santhosh, C. E-mail: unnikrishnan.vk@manipal.edu; Sonavane, M. S.; Yeotikar, R. G.; Shah, M. L.; Gupta, G. P.; Suri, B. M.

    2014-09-15

    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 1.7×10{sup 9} W/cm{sup 2}. 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.

  19. High-throughput quantitative biochemical characterization of algal biomass by NIR spectroscopy; multiple linear regression and multivariate linear regression analysis.

    PubMed

    Laurens, L M L; Wolfrum, E J

    2013-12-18

    One of the challenges associated with microalgal biomass characterization and the comparison of microalgal strains and conversion processes is the rapid determination of the composition of algae. We have developed and applied a high-throughput screening technology based on near-infrared (NIR) spectroscopy for the rapid and accurate determination of algal biomass composition. We show that NIR spectroscopy can accurately predict the full composition using multivariate linear regression analysis of varying lipid, protein, and carbohydrate content of algal biomass samples from three strains. We also demonstrate a high quality of predictions of an independent validation set. A high-throughput 96-well configuration for spectroscopy gives equally good prediction relative to a ring-cup configuration, and thus, spectra can be obtained from as little as 10-20 mg of material. We found that lipids exhibit a dominant, distinct, and unique fingerprint in the NIR spectrum that allows for the use of single and multiple linear regression of respective wavelengths for the prediction of the biomass lipid content. This is not the case for carbohydrate and protein content, and thus, the use of multivariate statistical modeling approaches remains necessary. PMID:24229385

  20. Fourier transform mid-infrared spectroscopy (FT-MIR) combined with chemometrics for quantitative analysis of dextrin in Danshen (Salvia miltiorrhiza) granule.

    PubMed

    Guo, Tao; Feng, Wei-Hong; Liu, Xiao-Qian; Gao, Hui-Min; Wang, Zhi-Min; Gao, Liang-Liang

    2016-05-10

    The granule of Chinese medicine (GCM) is prepared by water-soluble extract of single yinpian (WESY) of herbal medicine, and used as a drug ingredient for clinical formulation. The WESY content or corresponding yinpian amount is the most important parameter in evaluating the quality of GCM. Low WESY content reflects poor GCM. Classical quantitative methods, such as HPLC, cannot fully detect the adulteration by adding characteristic ingredients and less WESY production. GCM is composed of WESY and a high content of specific excipient. The WESY content in the GCM may be indirectly analyzed using mid-infrared spectroscopy (MIR). In this paper, a quantitative method to evaluate the quality of Danshen (Salvia miltiorrhiza) granule (DG) was developed using MIR combined with chemometrics. Appropriate characteristic quantitative regions (CQR) were extracted by selecting the spectral regions corresponding to altered excipient content in DG. The best model of dextrin content determination in DG with low RMSEC of 1.97, low RMSEP of 2.07, and excellent RPD of 5.03 (>5.0) was obtained using partial least-squares (PLS) regression, and validated using accepted values of precision and recovery. The results suggest that FT-MIR combined with PLS is a rapid and valuable analytical tool to determine the WESY in DG based on excipient content. The model enabling indirect calculation of WESY content in GCM represents a reference standard for rapid analysis of other WESYs in GCM industry. PMID:26859611

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

    PubMed

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

    2013-04-15

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

  2. Quantitative determination of lead in mixtures of lead(II) halides using solid-state 207Pb NMR spectroscopy.

    PubMed

    Glatfelter, Alicia; Stephenson, Nicole; Bai, Shi; Dybowski, Cecil; Perry, Dale L

    2006-11-01

    We demonstrate a multi-spectrum technique for facile, quantitative determination of lead in solid materials using solid-state (207)Pb NMR that avoids the major problem of uniform excitation across a wide spectral range; the method can be employed without chemical separation or other chemical manipulations and without any prior sample preparation, resulting in a non-destructive analysis, and producing results that are in agreement with gravimetric analyses of mixed samples of the lead halides. PMID:17066187

  3. Laser-induced Breakdown spectroscopy quantitative analysis method via adaptive analytical line selection and relevance vector machine regression model

    NASA Astrophysics Data System (ADS)

    Yang, Jianhong; Yi, Cancan; Xu, Jinwu; Ma, Xianghong

    2015-05-01

    A new LIBS quantitative analysis method based on analytical line adaptive selection and Relevance Vector Machine (RVM) regression model is proposed. First, a scheme of adaptively selecting analytical line is put forward in order to overcome the drawback of high dependency on a priori knowledge. The candidate analytical lines are automatically selected based on the built-in characteristics of spectral lines, such as spectral intensity, wavelength and width at half height. The analytical lines which will be used as input variables of regression model are determined adaptively according to the samples for both training and testing. Second, an LIBS quantitative analysis method based on RVM is presented. The intensities of analytical lines and the elemental concentrations of certified standard samples are used to train the RVM regression model. The predicted elemental concentration analysis results will be given with a form of confidence interval of probabilistic distribution, which is helpful for evaluating the uncertainness contained in the measured spectra. Chromium concentration analysis experiments of 23 certified standard high-alloy steel samples have been carried out. The multiple correlation coefficient of the prediction was up to 98.85%, and the average relative error of the prediction was 4.01%. The experiment results showed that the proposed LIBS quantitative analysis method achieved better prediction accuracy and better modeling robustness compared with the methods based on partial least squares regression, artificial neural network and standard support vector machine.

  4. Biogenic unmodified gold nanoparticles for selective and quantitative detection of cerium using UV-vis spectroscopy and photon correlation spectroscopy (DLS).

    PubMed

    Priyadarshini, E; Pradhan, N; Panda, P K; Mishra, B K

    2015-06-15

    The ability of self-functionalized biogenic GNPs towards highly selective colorimetric detection of rare earth element cerium is being reported for the first time. GNPs underwent rapid aggregation on addition of cerium indicated by red shift of SPR peak followed by complete precipitation. Hereby, this concept of co-ordination of cerium ions onto the GNP surface has been utilized for detection of cerium. The remarkable capacity of GNPs to sensitively detect Ce without proves beneficial compared to previous reports of colorimetric sensing. MDL was 15 and 35 ppm by DLS and UV-vis spectroscopy respectively, suggesting DLS to be highly sensitive and a practical alternative in ultrasensitive detection studies. The sensing system showed a good linear fit favouring feasible detection of cerium in range of 2-50 ppm. Similar studies further showed the superior selectivity of biogenic GNPs compared to chemically synthesized counterparts. The sensing system favours on-site analysis as it overcomes need of complex instrumentation, lengthy protocols and surface modification of GNP. PMID:25643600

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

    NASA Astrophysics Data System (ADS)

    Nawar, Said; Buddenbaum, Henning; Hill, Joachim

    2014-05-01

    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.

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

    SciTech Connect

    Keller, E.L.

    2000-06-27

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

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

    PubMed

    Duquesnoy, Emilie; Castola, Vincent; Casanova, Joseph

    2008-04-01

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

  8. Development and Evaluation of a PCR and Mass Spectroscopy-based (PCR-MS) Method for Quantitative, Type-specific Detection of Human Papillomavirus

    PubMed Central

    Patel, Divya A.; Shih, Yang-Jen; Newton, Duane W.; Michael, Claire W.; Oeth, Paul A.; Kane, Michael D.; Opipari, Anthony W.; Ruffin, Mack T.; Kalikin, Linda M.; Kurnit, David M.

    2010-01-01

    Knowledge of the central role of high-risk human papillomavirus (HPV) in cervical carcinogenesis, coupled with an emerging need to monitor the efficacy of newly introduced HPV vaccines, warrant development and evaluation of type-specific, quantitative HPV detection methods. In the present study, a prototype PCR and mass spectroscopy (PCR-MS)-based method to detect and quantitate 13 high-risk HPV types is compared to the Hybrid Capture 2 High Risk HPV DNA test (HC2; Digene Corp., Gaithersburg, MD) in 199 cervical scraping samples and to DNA sequencing in 77 cervical tumor samples. High-risk HPV types were detected in 76/77 (98.7%) cervical tumor samples by PCR-MS. Degenerate and type-specific sequencing confirmed the types detected by PCR-MS. In 199 cervical scraping samples, all 13 HPV types were detected by PCR-MS. Eighteen (14.5%) of 124 cervical scraping samples that were positive for high-risk HPV by HC2 were negative by PCR-MS. In all these cases, degenerate DNA sequencing failed to detect any of the 13 high-risk HPV types. Nearly half (46.7%) of the 75 cervical scraping samples that were negative for high-risk HPV by the HC2 assay were positive by PCR-MS. Type-specific sequencing in a subset of these samples confirmed the HPV type detected by PCR-MS. Quantitative PCR-MS results demonstrated that 11/75 (14.7%) samples contained as much HPV copies/cell as HC2-positive samples. These findings suggest that this prototype PCR-MS assay performs at least as well as HC2 for HPV detection, while offering the additional, unique advantages of type-specific identification and quantitation. Further validation work is underway to define clinically meaningful HPV detection thresholds and to evaluate the potential clinical application of future generations of the PCR-MS assay. PMID:19410602

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

    SciTech Connect

    Raeburn, S.P.; Ilton, E.S.; Veblen, D.R.

    1997-11-01

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

  10. Quantitative Decoupling of Excited-State Absorption Cross Section and Population via Pump-Probe Spectroscopy with a Strong Probe

    NASA Astrophysics Data System (ADS)

    Barker, Alex J.; Hodgkiss, Justin M.

    2015-08-01

    Photoinduced absorption signals measured by transient absorption spectroscopy are typically proportional to the product of absorption cross section (σ ) and excited-state density (N ). We show that this approximation does not hold at high probe-pulse intensities, and introduce the use of probe-intensity-dependent spectroscopy to decouple the two parameters. The singlet excited-state (S1→S2) absorption cross section of the conjugated polymer F8BT is measured to be 1.6 ×10-16 cm2±40 % at 800 nm and 3.7×10 -16 cm2±30 % at 900 nm, with no variation over the time window surveyed. The robustness of these parameters is established by observing that only N scales with excitation fluence and time delay, and conversely only σ is dependent on probe wavelength. The technique may be useful for quantifying salient parameters in many systems, such as branching yields in systems exhibiting singlet fission or triplet production, or cross sections required for photophysical models.

  11. Quantitative measurement of optical parameters in normal breasts using time-resolved spectroscopy: in vivo results of 30 Japanese women

    NASA Astrophysics Data System (ADS)

    Suzuki, Kazunori; Yamashita, Yutaka; Ohta, Kazuyoshi; Kaneko, Masao; Yoshida, Masayuki; Chance, Britton

    1996-07-01

    Previous investigation has proved time-resolved spectroscopy to be applicable to measurement of optical parameters in the human breast. To increase knowledge of these properties in vivo, the optical parameters of healthy breasts were measured using time-resolved reflectance spectroscopy. A time-correlated single-photon counting method was used to obtain time-response curves for the breasts of 30 Japanese women. Values of (mu) a and (mu) s$' were analyzed by fitting the curves to the diffusion equation. The relationships of optical parameters to age, body mass index, thickness of the breast, number of pregnancies, and menstrual status were examined. The (mu) a and (mu) s' ranged from 0.0024 to 0.0078/mm and from 0.63 to 1.08/mm, respectively. The values of (mu) a and (mu) s' showed a high correlation with properties may be strongly influenced by changes in tissue components related to aging, menstrual status, and so on. This optical information will contribute to the investigation of photon migration in the human breast.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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 [β- carotene]/μs' is a diagnostically important parameter but both parameters, [β-carotene] and μs', 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 [β-carotene] and μs' 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.

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

    NASA Astrophysics Data System (ADS)

    Schulz, Hartwig; Quilitzsch, Rolf; Krüger, Hans

    2003-12-01

    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, γ-terpinene, α-bisabolol and β-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.

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

    NASA Astrophysics Data System (ADS)

    Shen, Qinmei; Zhou, Weidong; Li, Kexue

    2010-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Agresti, Juri; Siano, Salvatore

    2014-10-01

    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.

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

    PubMed

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

    2013-10-15

    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

  17. Quantitative PVP mapping in PVDF hollow fiber membranes by using Raman spectroscopy coupled with spectral chemiometrics analysis

    NASA Astrophysics Data System (ADS)

    Dufour, E.; Gassara, S.; Petit, E.; Pochat-Bohatier, C.; Deratani, A.

    2015-07-01

    Fabrication of fouling resistant UF membranes requires the use of hydrophilic polymer additives that must be trapped in the polymer matrix during the phase separation processing. The knowledge of the polymeric additive distribution across the whole thickness should help to the design of more efficient membranes. This paper aims at developing a new methodology based on Raman microscopy spectroscopy owing to its high spatial resolution. A UF hollow fiber made from a blend of PVDF as polymer matrix and PVP as additive was chosen as a model membrane for this study. The PVP concentration profile along the cross-section radial axis was determined by using two ways of spectrum treatment including the analytical method by the peak intensity ratio calculation and a multivariate analysis with a partial least-squares regression model. The feasibility of the two approaches was discussed.

  18. Method of quantitative measurements of one- and two-photon absorption spectra obtained by intracavity laser spectroscopy

    SciTech Connect

    Baev, V.M.; Gamalii, V.F.; Sviridenkov, E.A.; Toptygin, D.D.; Yushchuk, O.I.

    1987-10-01

    The authors show the possibility of performing accurate measurements of the absorption coefficients and the integrated absorption sections for spectral lines of metal ion vapors recorded by intracavity laser spectroscopy even in the situation when the apparatus function of the instrument is several times greater than the width of the spectral line. This is especially significant for the study of two-photon absorption lines because these lines have a narrow central component due to the partial compensation of the Doppler broadening on the use of counter light beams. Their method was used to measure the integrated two-photon absorption sections of potassium vapor placed in the cavity of a dye laser and pumped by a ruby laser.

  19. Infrared spectroscopy for a quantitative determination of CH3-nClnCOCl in TiCl4

    NASA Astrophysics Data System (ADS)

    Yang, B.; Wang, Y.; Tan, H.; He, J.; Song, G.

    2015-12-01

    Infrared spectroscopy permits a determination of the concentration of CHCl2COCl, CH2ClCOCl and CCl3COCl as the organic impurities in TiCl4. In this study, an infrared spectrometer with ZnSe window and the cell of PTFE was assembled, and used to determine the concentration of three organic impurities. The detection limits of CCl3COCl, CHCl2COCl, CH2ClCOCl were determined as 3.16×10-3 μg/g 1.92×10-3 μg/g and 1.55×10-2 μg/g respectively. The new method is applied to quality control of refined TiCl4 from titanium sponge.

  20. Quantitative Prediction of Beef Quality Using Visible and NIR Spectroscopy with Large Data Samples Under Industry Conditions

    NASA Astrophysics Data System (ADS)

    Qiao, T.; Ren, J.; Craigie, C.; Zabalza, J.; Maltin, Ch.; Marshall, S.

    2015-03-01

    It is well known that the eating quality of beef has a significant influence on the repurchase behavior of consumers. There are several key factors that affect the perception of quality, including color, tenderness, juiciness, and flavor. To support consumer repurchase choices, there is a need for an objective measurement of quality that could be applied to meat prior to its sale. Objective approaches such as offered by spectral technologies may be useful, but the analytical algorithms used remain to be optimized. For visible and near infrared (VISNIR) spectroscopy, Partial Least Squares Regression (PLSR) is a widely used technique for meat related quality modeling and prediction. In this paper, a Support Vector Machine (SVM) based machine learning approach is presented to predict beef eating quality traits. Although SVM has been successfully used in various disciplines, it has not been applied extensively to the analysis of meat quality parameters. To this end, the performance of PLSR and SVM as tools for the analysis of meat tenderness is evaluated, using a large dataset acquired under industrial conditions. The spectral dataset was collected using VISNIR spectroscopy with the wavelength ranging from 350 to 1800 nm on 234 beef M. longissimus thoracis steaks from heifers, steers, and young bulls. As the dimensionality with the VISNIR data is very high (over 1600 spectral bands), the Principal Component Analysis (PCA) technique was applied for feature extraction and data reduction. The extracted principal components (less than 100) were then used for data modeling and prediction. The prediction results showed that SVM has a greater potential to predict beef eating quality than PLSR, especially for the prediction of tenderness. The infl uence of animal gender on beef quality prediction was also investigated, and it was found that beef quality traits were predicted most accurately in beef from young bulls.

  1. Investigation of the reaction of 1,3-dimethylurea with formaldehyde by quantitative on-line NMR spectroscopy: a model for the urea-formaldehyde system.

    PubMed

    Steinhof, Oliver; Scherr, Günter; Hasse, Hans

    2016-06-01

    Quantitative on-line NMR spectroscopy is applied to study equilibria and reaction kinetics of the reaction of formaldehyde with 1,3-dimethylurea. This reaction system serves as a model system for the much more complex but industrially relevant urea-formaldehyde system. The aim is to study individual reactions and intermediates. The 1,3-dimethylurea-formaldehyde system undergoes only four reactions and, unlike urea-formaldehyde, does not form polymers. The following reactions are studied in detail: (1) the hydroxymethylation, (2) the formation of hemiformals of the hydroxymethylated intermediate, and (3) two condensation reactions of which the first leads to methylene bridges, the other to ether bridges. NMR spectroscopic chemical shift data of the reacting species are provided for the (1) H, (13) C, and (15) N domains. Equilibrium data of reactions (1), (2), and (3) are determined by quantitative (1) H and (13) C NMR spectroscopy at molar ratios of formaldehyde to 1,3-dimethylurea between 1:2 and 16:1 at a pH value of 8.5. Reaction kinetic experiments using an NMR spectrometer coupled to a batch reactor led to a reaction kinetic model parametrized with true species concentrations. The model takes into account reactions (1), (2), and (3). It describes the reaction system well for molar ratios of 1:1, 2:1, and 4:1, temperatures of 303 to 333K, and pH values from 5.0 to 9.5. Dilution experiments with a micro mixer coupled to the NMR spectrometer are conducted to estimate the time to equilibrium of reaction (2) of which the time constant is significantly lower than those of reactions (1) and (3). Copyright © 2015 John Wiley & Sons, Ltd. PMID:26095823

  2. Simple, fast, and accurate methodology for quantitative analysis using Fourier transform infrared spectroscopy, with bio-hybrid fuel cell examples

    PubMed Central

    Mackie, David M.; Jahnke, Justin P.; Benyamin, Marcus S.; Sumner, James J.

    2016-01-01

    The standard methodologies for quantitative analysis (QA) of mixtures using Fourier transform infrared (FTIR) instruments have evolved until they are now more complicated than necessary for many users’ purposes. We present a simpler methodology, suitable for widespread adoption of FTIR QA as a standard laboratory technique across disciplines by occasional users.•Algorithm is straightforward and intuitive, yet it is also fast, accurate, and robust.•Relies on component spectra, minimization of errors, and local adaptive mesh refinement.•Tested successfully on real mixtures of up to nine components. We show that our methodology is robust to challenging experimental conditions such as similar substances, component percentages differing by three orders of magnitude, and imperfect (noisy) spectra. As examples, we analyze biological, chemical, and physical aspects of bio-hybrid fuel cells. PMID:26977411

  3. Quantitative structural constraints for organic powders at natural isotopic abundance using dynamic nuclear polarization solid-state NMR spectroscopy.

    PubMed

    Mollica, Giulia; Dekhil, Myriam; Ziarelli, Fabio; Thureau, Pierre; Viel, Stéphane

    2015-05-11

    A straightforward method is reported to quantitatively relate structural constraints based on (13)C-(13)C double-quantum build-up curves obtained by dynamic nuclear polarization (DNP) solid-state NMR to the crystal structure of organic powders at natural isotopic abundance. This method relies on the significant gain in NMR sensitivity provided by DNP (approximately 50-fold, lowering the experimental time from a few years to a few days), and is sensitive to the molecular conformation and crystal packing of the studied powder sample (in this case theophylline). This method allows trial crystal structures to be rapidly and effectively discriminated, and paves the way to three-dimensional structure elucidation of powders through combination with powder X-ray diffraction, crystal-structure prediction, and density functional theory computation of NMR chemical shifts. PMID:25809550

  4. Quantitative Phase Composition of TiO2-Coated Nanoporous-Au Monoliths by X-ray Absorption Spectroscopy and Correlations to Catalytic

    DOE PAGESBeta

    Bagge-Hansen, Michael; Wichmann, Andre; Wittstock, Arne; Lee, Jonathan R. I.; Ye, Jianchao; Willey, Trevor M.; Kuntz, Joshua D.; van Buuren, Tony; Biener, Juergen; Baumer, Marcus; et al

    2014-02-03

    Porous titania/metal composite materials have many potential applications in the fields of green catalysis, energy harvesting, and storage in which both the overall morphology of the nanoporous host material and the crystallographic phase of the titania (TiO 2) guest determine the material’s performance. New insights into the structure–function relationships of these materials were obtained by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy that, for example, provides quantitative crystallographic phase composition from ultrathin, nanostructured titania films, including sensitivity to amorphous components. We demonstrate that crystallographic phase, morphology, and catalytic activity of TiO 2-functionalized nanoporous gold (np-Au) can be controlled by amore » simple annealing procedure (T < 1300 K). The material was prepared by atomic layer deposition of ~2 nm thick TiO2 on millimeter-sized samples of np-Au (40–50 nm mean ligament size) and catalytically investigated with respect to aerobic CO oxidation. Moreover, the annealing-induced changes in catalytic activity are correlated with concurrent morphology and phase changes as provided by cross-sectional scanning electron microscopy, transmission electron microscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy.« less

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

    PubMed

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

    2014-01-21

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

  6. Quantitative Phase Composition of TiO2-Coated Nanoporous-Au Monoliths by X-ray Absorption Spectroscopy and Correlations to Catalytic

    SciTech Connect

    Bagge-Hansen, Michael; Wichmann, Andre; Wittstock, Arne; Lee, Jonathan R. I.; Ye, Jianchao; Willey, Trevor M.; Kuntz, Joshua D.; van Buuren, Tony; Biener, Juergen; Baumer, Marcus; Biener, Monika M.

    2014-02-03

    Porous titania/metal composite materials have many potential applications in the fields of green catalysis, energy harvesting, and storage in which both the overall morphology of the nanoporous host material and the crystallographic phase of the titania (TiO 2) guest determine the material’s performance. New insights into the structure–function relationships of these materials were obtained by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy that, for example, provides quantitative crystallographic phase composition from ultrathin, nanostructured titania films, including sensitivity to amorphous components. We demonstrate that crystallographic phase, morphology, and catalytic activity of TiO 2-functionalized nanoporous gold (np-Au) can be controlled by a simple annealing procedure (T < 1300 K). The material was prepared by atomic layer deposition of ~2 nm thick TiO2 on millimeter-sized samples of np-Au (40–50 nm mean ligament size) and catalytically investigated with respect to aerobic CO oxidation. Moreover, the annealing-induced changes in catalytic activity are correlated with concurrent morphology and phase changes as provided by cross-sectional scanning electron microscopy, transmission electron microscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy.

  7. A rapid qualitative and quantitative evaluation of grape berries at various stages of development using Fourier-transform infrared spectroscopy and multivariate data analysis.

    PubMed

    Musingarabwi, Davirai M; Nieuwoudt, Hélène H; Young, Philip R; Eyéghè-Bickong, Hans A; Vivier, Melané A

    2016-01-01

    Fourier transform (FT) near-infrared (NIR) and attenuated total reflection (ATR) FT mid-infrared (MIR) spectroscopy were used to qualitatively and quantitatively analyse Vitis vinifera L. cv Sauvignon blanc grape berries. FT-NIR and ATR FT-MIR spectroscopy, coupled with spectral preprocessing and multivariate data analysis (MVDA), provided reliable methods to qualitatively assess berry samples at five distinct developmental stages: green, pre-véraison, véraison, post-véraison and ripe (harvest), without any prior metabolite extraction. Compared to NIR spectra, MIR spectra provided more reliable discrimination between the berry samples from the different developmental stages. Interestingly, ATR FT-MIR spectra from fresh homogenized berry samples proved more discriminatory than spectra from frozen homogenized berry samples. Different developmental stages were discriminated by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). In order to generate partial least squares (PLS) models from the MIR/NIR spectral datasets; the major sugars (glucose and fructose) and organic acids (malic acid, succinic acid and tartaric acid) were separated and quantified by high performance liquid chromatography (HPLC) and the data used as a reference dataset. PLS regression was used to develop calibration models to predict the concentration of the major sugars and organic acids in the berry samples from different developmental stages. Our data show that infrared (IR) spectroscopy could provide a rapid, reproducible and cost-effective alternative to the chromatographic analysis of the sugar and organic acid composition of grape berries at various developmental stages, using small sample volumes and requiring limited sample preparation. This provides scope and support for the possible development of hand-held devices to assess quality parameters in field-settings in real-time and non-destructively using IR technologies. PMID:26212968

  8. 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)

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

    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.

  9. Quantitative Metabolomic Profiling of Serum, Plasma, and Urine by 1H NMR Spectroscopy Discriminates between Patients with Inflammatory Bowel Disease and Healthy Individuals

    PubMed Central

    2012-01-01

    Serologic biomarkers for inflammatory bowel disease (IBD) have yielded variable differentiating ability. Quantitative analysis of a large number of metabolites is a promising method to detect IBD biomarkers. Human subjects with active Crohn’s disease (CD) and active ulcerative colitis (UC) were identified, and serum, plasma, and urine specimens were obtained. We characterized 44 serum, 37 plasma, and 71 urine metabolites by use of 1H NMR spectroscopy and “targeted analysis” to differentiate between diseased and non-diseased individuals, as well as between the CD and UC cohorts. We used multiblock principal component analysis and hierarchical OPLS-DA for comparing several blocks derived from the same “objects” (e.g., subject) to examine differences in metabolites. In serum and plasma of IBD patients, methanol, mannose, formate, 3-methyl-2-oxovalerate, and amino acids such as isoleucine were the metabolites most prominently increased, whereas in urine, maximal increases were observed for mannitol, allantoin, xylose, and carnitine. Both serum and plasma of UC and CD patients showed significant decreases in urea and citrate, whereas in urine, decreases were observed, among others, for betaine and hippurate. Quantitative metabolomic profiling of serum, plasma, and urine discriminates between healthy and IBD subjects. However, our results show that the metabolic differences between the CD and UC cohorts are less pronounced. PMID:22574726

  10. Quantitative Analysis of Hexahydro-1,3,5-trinitro-1,3,5, Triazine/Pentaerythritol Tetranitrate (RDX-PETN) Mixtures by Terahertz Time Domain Spectroscopy.

    PubMed

    Sleiman, Joyce Bou; Bousquet, Bruno; Palka, Norbert; Mounaix, Patrick

    2015-12-01

    Absorption spectra of explosives such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), pentaerythritol tetranitrate (PETN), and mixtures of both were measured by terahertz time domain spectroscopy (THz-TDS). Chemometrics was applied to quantitative analysis of terahertz absorbance spectra obtained in transmission mode to predict the relative amounts of RDX and PETN in samples containing pure components or their mixtures. This analysis was challenging because significant spectral overlap prevented identification of each product fingerprint. Partial least squares (PLS) regression models were thus applied to the terahertz spectra. A comparison between the so-called PLS1 and PLS2 algorithms was performed to predict the PETN concentrations in mixture samples. PLS2 demonstrated better predictive ability than PLS1 with RMSE value lower than 3.5 mg for 400 mg total weight pellets. Moreover, the influence of the highly overlapping spectral frequency band was investigated by reducing the original 0.2-3 THz (6-100 cm(-1)) spectral band to 1.8-3 THz (60-100 cm(-1)). The predictive ability was quite similar in both cases, highlighting the excellent ability of chemometrics to perform quantitative analysis when applied to THz-TDS data, even in the case of highly overlapping spectra. PMID:26556760

  11. Quantitative metabolic profiles of 2nd and 3rd trimester human amniotic fluid using 1H HR-MAS spectroscopy

    PubMed Central

    Cohn, Brad R.; Zhao, Shoujun; Kornak, John; Zhang, Vickie Y.; Iman, Rahwa; Kurhanewicz, John; Vahidi, Kiarash; Yu, Jingwei; Caughey, Aaron B.; Swanson, Mark G.

    2016-01-01

    Object To establish and compare normative metabolite concentrations in 2nd and 3rd trimester human amniotic fluid samples in an effort to reveal metabolic biomarkers of fetal health and development. Materials and methods Twenty-one metabolite concentrations were compared between 2nd (15–27 weeks gestation, N = 23) and 3rd (29–39 weeks gestation, N = 27) trimester amniotic fluid samples using 1H high resolution magic angle spinning (HR-MAS) spectroscopy. Data were acquired using the electronic reference to access in vivo concentrations method and quantified using a modified semi-parametric quantum estimation algorithm modified for high-resolution ex vivo data. Results Sixteen of 21 metabolite concentrations differed significantly between 2nd and 3rd trimester groups. Betaine (0.00846±0.00206 mmol/kg vs. 0.0133±0.0058 mmol/kg, P <0.002) and creatinine (0.0124±0.0058 mmol/kg vs. 0.247±0.011 mmol/kg, P <0.001) concentrations increased significantly, while glucose (5.96±1.66 mmol/kg vs. 2.41±1.69 mmol/kg, P <0.001), citrate (0.740±0.217 mmol/kg vs. 0.399±0.137 mmol/kg, P <0.001), pyruvate (0.0659±0.0103 mmol/kg vs. 0.0299±0.286 mmol/kg, P <0.001), and numerous amino acid (e.g. alanine, glutamate, isoleucine, leucine, lysine, and valine) concentrations decreased significantly with advancing gestation. A stepwise multiple linear regression model applied to 50 samples showed that gestational age can be accurately predicted using combinations of alanine, glucose and creatinine concentrations. Conclusion These results provide key normative data for 2nd and 3rd trimester amniotic fluid metabolite concentrations and provide the foundation for future development of magnetic resonance spectroscopy (MRS) biomarkers to evaluate fetal health and development. PMID:19779747

  12. Combined fiber probe for fluorescence lifetime and Raman spectroscopy.

    PubMed

    Dochow, Sebastian; Ma, Dinglong; Latka, Ines; Bocklitz, Thomas; Hartl, Brad; Bec, Julien; Fatakdawala, Hussain; Marple, Eric; Urmey, Kirk; Wachsmann-Hogiu, Sebastian; Schmitt, Michael; Marcu, Laura; Popp, Jürgen

    2015-11-01

    In this contribution we present a dual modality fiber optic probe combining fluorescence lifetime imaging (FLIm) and Raman spectroscopy for in vivo endoscopic applications. The presented multi-spectroscopy probe enables efficient excitation and collection of fluorescence lifetime signals for FLIm in the UV/visible wavelength region, as well as of Raman spectra in the near-IR for simultaneous Raman/FLIm imaging. The probe was characterized in terms of its lateral resolution and distance dependency of the Raman and FLIm signals. In addition, the feasibility of the probe for in vivo FLIm and Raman spectral characterization of tissue was demonstrated. Graphical Abstract An image comparison between FLIm and Raman spectroscopy acquired with the bimodal probe onseveral tissue samples. PMID:26093843

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

    SciTech Connect

    Prieto, P.; Morant, C.; Climent-Font, A.; Munoz, A.; Elizalde, E.; Sanz, J.M.

    2006-03-15

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

  14. Quantitative detection of metallic traces in water-based liquids by microwave-assisted laser-induced breakdown spectroscopy.

    PubMed

    Wall, Matthew; Sun, Zhiwei; Alwahabi, Zeyad T

    2016-01-25

    The enhancement of laser-induced breakdown spectroscopy (LIBS) assisted with microwave radiation is demonstrated for an aqueous solution of indium using the 451.13 nm emission line. Microwave power was delivered via a near-field applicator to the LIBS measurement volume where the indium aqueous solution was presented as a liquid jet. The microwave enhancement effect was observed to decrease with increasing laser pulse fluence at 532 nm resulting in a maximum emission intensity occurring at a laser pulse fluence of 85.2 J∙cm-2, independent of the microwave power used. The detection limits of indium in an aqueous solution were determined to be 10.8 ± 0.7 and 124 ± 5 ppm for the cases of microwave enhanced and standard LIBS, respectively. The 11.5-fold detection limit enhancement obtained in the liquid phase is of the same order of magnitude as that reported for other elements in solid samples, but lower than that obtained in solid phase utilizing a similar experimental setup. This establishes microwave enhancement as an effective technique for the detection of metals in aqueous solutions. In addition, the temporal evolution of plasma emission intensity was investigated and was found to be qualitatively similar to that of plasma produced from solid phase samples, which reveals the same coupling mechanism between laser generated plasma and microwave radiation. PMID:26832530

  15. Quantitative Analysis of Carbon Content in Bituminous Coal by Laser-Induced Breakdown Spectroscopy Using UV Laser Radiation

    NASA Astrophysics Data System (ADS)

    Li, Xiongwei; Mao, Xianglei; Wang, Zhe; Richard, E. Russo

    2015-11-01

    The carbon content of bituminous coal samples was analyzed by laser-induced breakdown spectroscopy. The 266 nm laser radiation was utilized for laser ablation and plasma generation in air. The partial least square method and the dominant factor based PLS method were used to improve the measurement accuracy of the carbon content of coal. The results showed that the PLS model could achieve good measurement accuracy, and the dominant factor based PLS model could further improve the measurement accuracy. The coefficient of determination and the root-mean-square error of prediction of the PLS model were 0.97 and 2.19%, respectively; and those values for the dominant factor based PLS model were 0.99 and 1.51%, respectively. The results demonstrated that the 266 nm wavelength could accurately measure the carbon content of bituminous coal. supported by National Natural Science Foundation of China (No. 51276100) and the National Basic Research Program of China (973 Program) (No. 2013CB228501). The authors also thank the financial funding from the U. S. Department of Energy, Office of Basic Energy Sciences, Chemical Science Division at Lawrence Berkeley National Laboratory (No. 2013CB228501)

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

    SciTech Connect

    Raeburn, S.P.; Ilton, E.S.; Veblen, D.R.

    1997-11-01

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

  17. Gannet: A Batch-Processing Tool for the Quantitative Analysis of Gamma-Aminobutyric Acid–Edited MR Spectroscopy Spectra

    PubMed Central

    Edden, Richard A.E.; Puts, Nicolaas A.J.; Harris, Ashley D.; Barker, Peter B.; Evans, C. John

    2014-01-01

    Purpose The purpose of this study is to describe the Gannet toolkit for the quantitative batch analysis of gamma-aminobutyric acid (GABA) -edited MRS data. Materials and Methods Using MEGA-PRESS editing and standard acquisition parameters, four MEGA-PRESS spectra were acquired in three brain regions in 10 healthy volunteers. These 120 datasets were processed without user intervention with Gannet, a Matlab-based tool that takes raw time-domain data input, processes it to generate the frequency-domain edited spectrum, and applies a simple modeling procedure to estimate GABA concentration relative to the creatine or, if provided, the unsuppressed water signal. A comparison of four modeling approaches is also presented. Results All data were successfully processed by Gannet. Coefficients of variation across subjects ranged from 11% for the occipital region to 17% for the dorsolateral prefrontal region. There was no clear difference in fitting performance between the simple Gaussian model used by Gannet and the other more complex models presented. Conclusion Gannet, the GABA Analysis Toolkit, can be used to process and quantify GABA-edited MRS spectra without user intervention. PMID:25548816

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

    PubMed

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

    2013-08-01

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

  19. Organic matter transformation in the environment investigated by quantitative electron paramagnetic resonance (EPR) spectroscopy: studies on lignins

    NASA Astrophysics Data System (ADS)

    Czechowski, Franciszek; Golonka, Iwona; Jezierski, Adam

    2004-05-01

    The lignins separated from angiosperm and gymnosperm trees, peat and xylitic brown coal were investigated by quantitative EPR. Observed free radicals in lignins are sensitive to alkaline environment. Gaseous ammonia interacting with solid lignins in resonance cavity shifts quinone-hydroquinone equilibria towards formation of semiquinone anions. Complexation of copper(II) by lignins causes drastic decrease of the semiquinones in the matrices. Formation of lignin-Pb(II) complexes yielded radicals characterised by unusually low g-value (1.9999-2.0003). Monomeric structural units of the investigated lignins were recognised by pyrolysis with in situ methylation by tetramethylammonium hydroxide. Although for the natural lignins the mixture of normal semiquinone signals at g about 2.0034 and signals at g 1.9999 were observed, some monomeric components of lignins (e.g., caffeic acid, pyrogallol) gave pure lines at g=1.9999. The bacterial oxidative biodegradation of lignin monomeric components and their Pb(II) complexes resulted in increase of the radical signals.

  20. Ultrasonic nebulization-sample introduction system for quantitative analysis of liquid samples by laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Aras, Nadir; Yeşiller, Semira Ünal; Ateş, Dilek Arıca; Yalçın, Şerife

    2012-08-01

    In this study, design and optimization studies of a sample introduction system based on ultrasonic nebulization of metal salts in aqueous environment for laser-induced breakdown spectroscopic detection were presented. The system consisted of an ultrasonic nebulizer connected to a tandem heater-condenser-membrane dryer unit that produces sub-micron size aerosols. Results indicate improvements in detection limits for some elements with the use of membrane dryer. Optimization studies were performed by systematical investigation of LIBS emission signal with respect to laser energy, carrier gas flow rate and detector timing parameters. Under optimized conditions, calibration graphs for Na, K, Mg, Ca, Cu, Al, Cr, Cd, Pb and Zn were constructed and detection limits were calculated. The applicability of the ultrasonic nebulization-LIBS system was tested on real water samples. This system establishes LIBS as an effective analytical tool for both qualitative and quantitative determination of metal aerosols in aqueous environments. This technique is sufficiently rapid to provide real-time monitoring of toxic metals.

  1. 2D IR Spectroscopy using Four-Wave Mixing, Pulse Shaping, and IR Upconversion: A Quantitative Comparison

    PubMed Central

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

    2013-01-01

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

  2. Use and qualification of primary and secondary standards employed in quantitative ¹H NMR spectroscopy of pharmaceuticals.

    PubMed

    Rundlöf, Torgny; McEwen, Ian; Johansson, Monika; Arvidsson, Torbjörn

    2014-05-01

    Standards are required in quantitative NMR (qNMR) to obtain accurate and precise results. In this study acetanilide was established and used as a primary standard. Six other chemicals were selected as secondary standards: 3,4,5-trichloropyridine, dimethylterephthalate, maleic acid, 3-sulfolene, 1,4-bis(trimethylsilyl)benzene, and 1,3,5-trimethoxybenzene. The secondary standards were quantified using the primary standard acetanilide. A protocol for qualification and periodic checks of these secondary standards was developed, and used for evaluation of the stability of the compounds. Periodic monitoring of purity was performed for several years. The purity was higher than 99% for all secondary standards. All standards maintained the initial purity during the time period of monitoring, with very small variations in purity (0.3-0.4%). The selected secondary standards were shown to be suitable qNMR standards and that periodic requalification of the standards by qNMR ensures reliable analytical results. These standards have been used in our laboratory for compliance testing of pharmaceutical active substances and approved medicinal products as well as for analysis of suspected illegal medicines. In total more than 1000 samples have been tested using both internal and external standardization and examples are given. PMID:24206940

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

    PubMed

    Nicolaou, Nicoletta; Goodacre, Royston

    2008-10-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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 μm 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.

  5. Investigation of noise-induced instabilities in quantitative biological spectroscopy and its implications for noninvasive glucose monitoring.

    PubMed

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

    2012-10-01

    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 (nonlinear) 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 nonlinear 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 a 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 nonlinear spectroscopic models. Our results show that the 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 data set is as important, if not more so, than the generic accuracy level. PMID:22950485

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

    SciTech Connect

    Kudritzki, Rolf-Peter; Urbaneja, Miguel A.; Gazak, Zachary; Bresolin, Fabio; Przybilla, Norbert; Gieren, Wolfgang; Pietrzynski, Grzegorz E-mail: urbaneja@ifa.hawaii.edu E-mail: bresolin@ifa.hawaii.edu E-mail: wgieren@astro-udec.cl

    2012-03-01

    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.

  7. Plasma-particle interactions for the quantitative analysis of individual aerosol particles using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Carranza, Jorge E.

    In response to the need for discrete characterization of ambient air fine particles due to the direct relation of particle size and particle composition to human health effects, laser-induced breakdown spectroscopy (LIBS) has been studied in this dissertation to support its development as a real-time aerosol analysis technique capable of measuring particle size and particle composition. In Chapter 1, a literature review and the principles of LIBS are presented in the context of aerosol analysis. The complete experimental facilities are described in Chapter 2. An aerosol generation system was developed to produce well-dispersed aerosolized nanoparticles that served as the calibration source for the LIBS system. The LIBS system consists of a 1064-nm Nd:YAG pulse laser, supporting optics, and an intensified charge-coupled device for plasma emission quantification. The developed LIBS system was successfully deployed as discussed in Chapter 3 for ambient air monitoring (specifically aluminum, magnesium, calcium, and sodium). Mass concentrations were recorded on the order of low parts per trillion and minimum particle sizes about 200 nm. In Chapter 4, issues of plasma homogeneity and signal fluctuations on a shot-to-shot basis were addressed to elucidate optimal laser pulse energy for single shot analysis, thereby identifying a characteristic state of the plasma where signal fluctuations are minimized. The implicit assumption of complete particle vaporization is investigated in detail in Chapter 5, with the determination that silica particles up to 2.1-mum diameters are completely vaporized due to plasma-particle interactions. Finally, the characteristic plasma volumes related to the scheme of particle sizing are determined and analyzed in the context of the analysis of single aerosol particle detection. The outcome of this research yielded an enhanced understanding of single aerosol analysis with the LIBS technique. Important conclusions are that LIBS measurement should be made at the plasma saturation condition, particle sizing should be limited to about 2 mum or less, particle vaporization is driven by plasma-particle interactions, and that real-time ambient air monitoring is feasible with LIBS on time periods as short as 4 minutes.

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

    PubMed

    Edwards, C S; Christensen, P R

    2013-04-10

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

  9. On-line quantitative monitoring of liquid-liquid extraction of Lonicera japonica and Artemisia annua using near-infrared spectroscopy and chemometrics

    PubMed Central

    Wu, Sha; Jin, Ye; Liu, Qian; Liu, Qi-an; Wu, Jianxiong; Bi, Yu-an; Wang, Zhengzhong; Xiao, Wei

    2015-01-01

    Background: Liquid-liquid extraction of Lonicera japonica and Artemisia annua (JQ) plays a significant role in manufacturing Reduning injection. Many process parameters may influence liquid-liquid extraction and cause fluctuations in product quality. Objective: To develop a near-infrared (NIR) spectroscopy method for on-line monitoring of liquid-liquid extraction of JQ. Materials and Methods: Eleven batches of JQ extraction solution were obtained, ten for building quantitative models and one for assessing the predictive accuracy of established models. Neochlorogenic acid (NCA), chlorogenic acid (CA), cryptochlorogenic acid (CCA), isochlorogenic acid B (ICAB), isochlorogenic acid A (ICAA), isochlorogenic acid C (ICAC) and soluble solid content (SSC) were selected as quality control indicators, and measured by reference methods. NIR spectra were collected in transmittance mode. After selecting the spectral sub-ranges, optimizing the spectral pretreatment and neglecting outliers, partial least squares regression models were built to predict the content of indicators. The model performance was evaluated by the coefficients of determination (R2), the root mean square errors of prediction (RMSEP) and the relative standard error of prediction (RSEP). Results: For NCA, CA, CCA, ICAB, ICAA, ICAC and SSC, R2 was 0.9674, 0.9704, 0.9641, 0.9514, 0.9436, 0.9640, 0.9809, RMSEP was 0.0280, 0.2913, 0.0710, 0.0590, 0.0815, 0.1506, 1.167, and RSEP was 2.32%, 4.14%, 3.86%, 5.65%, 7.29%, 6.95% and 4.18%, respectively. Conclusion: This study demonstrated that NIR spectroscopy could provide good predictive ability in monitoring of the content of quality control indicators in liquid-liquid extraction of JQ. PMID:26246744

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

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  11. Direct Analysis of Free and Sulfite-Bound Carbonyl Compounds in Wine by Two-Dimensional Quantitative Proton and Carbon Nuclear Magnetic Resonance Spectroscopy.

    PubMed

    Nikolantonaki, Maria; Magiatis, Prokopios; Waterhouse, Andrew L

    2015-11-01

    Recent developments that have accelerated 2D NMR methods and improved quantitation have made these methods accessible analytical procedures, and the large signal dispersion allows for the analysis of complex samples. Few natural samples are as complex as wine, so the application to challenges in wine analysis look promising. The analysis of carbonyl compounds in wine, key oxidation products, is complicated by a multitude of kinetically reversible adducts, such as acetals and sulfonates, so that sample preparation steps can generate complex interferences. These challenges could be overcome if the compounds could be quantified in situ. Here, two-dimensional ((1)H-(1)H) homonuclear and heteronuclear ((13)C-(1)H) single quantum correlations (correlation spectroscopy, COSY, and heteronuclear single quantum coherence, HSQC) nuclear magnetic resonance spectra of undiluted wine samples were observed at natural abundance. These techniques achieve simultaneous direct identification and quantitation of acetaldehyde, pyruvic acid, acetoin, methylglyoxal, and ?-ketoglutaric acid in wine with only a small addition of D2O. It was also possible to observe and sometimes quantify the sulfite, hydrate, and acetal forms of the carbonyl compounds. The accuracy of the method was tested in wine samples by spiking with a mixture of all analytes at different concentrations. The method was applied to 15 wine samples of various vintages and grape varieties. The application of this method could provide a powerful tool to better understand the development, evolution, and perception of wine oxidation and insight into the impact of these sulfite bound carbonyls on antimicrobial and antioxidant action by SO2. PMID:26348554

  12. 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)

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

    2008-03-01

    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.

  13. Reduced cortical microvascular oxygenation in multiple sclerosis: a blinded, case-controlled study using a novel quantitative near-infrared spectroscopy method

    NASA Astrophysics Data System (ADS)

    Yang, Runze; Dunn, Jeff F.

    2015-11-01

    Hypoxia (low oxygen) is associated with many brain disorders as well as inflammation, but the lack of widely available technology has limited our ability to study hypoxia in human brain. Multiple sclerosis (MS) is a poorly understood neurological disease with a significant inflammatory component which may cause hypoxia. We hypothesized that if hypoxia were to occur, there should be reduced microvascular hemoglobin saturation (StO2). In this study, we aimed to determine if reduced StO2 can be detected in MS using frequency domain near-infrared spectroscopy (fdNIRS). We measured fdNIRS data in cortex and assessed disability of 3 clinical isolated syndrome (CIS), 72 MS patients and 12 controls. Control StO2 was 63.5 ± 3% (mean ± SD). In MS patients, 42% of StO2 values were more than 2 × SD lower than the control mean. There was a significant relationship between StO2 and clinical disability. A reduced microvascular StO2 is supportive (although not conclusive) that there may be hypoxic regions in MS brain. This is the first study showing how quantitative NIRS can be used to detect reduced StO2 in patients with MS, opening the door to understanding how microvascular oxygenation impacts neurological conditions.

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

    SciTech Connect

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

    2014-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  16. Region-specific effects on brain metabolites of hypoxia and hyperoxia overlaid on cerebral ischemia in young and old rats: a quantitative proton magnetic resonance spectroscopy study

    PubMed Central

    2010-01-01

    Background Both hypoxia and hyperoxia, deregulating the oxidative balance, may play a role in the pathology of neurodegenerative disorders underlain by cerebral ischemia. In the present study, quantitative proton magnetic resonance spectroscopy was used to evaluate regional metabolic alterations, following a 24-hour hypoxic or hyperoxic exposure on the background of ischemic brain insult, in two contrasting age-groups of rats: young - 3 months old and aged - 24 months old. Methods Cerebral ischemia was induced by ligation of the right common carotid artery. Concentrations of eight metabolites (alanine, choline-containing compounds, total creatine, γ-aminobutyric acid, glutamate, lactate, myo-inositol and N-acetylaspartate) were quantified from extracts in three different brain regions (fronto-parietal and occipital cortices and the hippocampus) from both hemispheres. Results In the control normoxic condition, there were significant increases in lactate and myo-inositol concentrations in the hippocampus of the aged rats, compared with the respective values in the young ones. In the ischemia-hypoxia condition, the most prevalent changes in the brain metabolites were found in the hippocampal regions of both young and aged rats; but the effects were more evident in the aged animals. The ischemia-hyperoxia procedure caused less dedicated changes in the brain metabolites, which may reflect more limited tissue damage. Conclusions We conclude that the hippocampus turns out to be particularly susceptible to hypoxia overlaid on cerebral ischemia and that old age further increases this susceptibility. PMID:20178616

  17. Reduced cortical microvascular oxygenation in multiple sclerosis: a blinded, case-controlled study using a novel quantitative near-infrared spectroscopy method

    PubMed Central

    Yang, Runze; Dunn, Jeff F.

    2015-01-01

    Hypoxia (low oxygen) is associated with many brain disorders as well as inflammation, but the lack of widely available technology has limited our ability to study hypoxia in human brain. Multiple sclerosis (MS) is a poorly understood neurological disease with a significant inflammatory component which may cause hypoxia. We hypothesized that if hypoxia were to occur, there should be reduced microvascular hemoglobin saturation (StO2). In this study, we aimed to determine if reduced StO2 can be detected in MS using frequency domain near-infrared spectroscopy (fdNIRS). We measured fdNIRS data in cortex and assessed disability of 3 clinical isolated syndrome (CIS), 72 MS patients and 12 controls. Control StO2 was 63.5 ± 3% (mean ± SD). In MS patients, 42% of StO2 values were more than 2 × SD lower than the control mean. There was a significant relationship between StO2 and clinical disability. A reduced microvascular StO2 is supportive (although not conclusive) that there may be hypoxic regions in MS brain. This is the first study showing how quantitative NIRS can be used to detect reduced StO2 in patients with MS, opening the door to understanding how microvascular oxygenation impacts neurological conditions. PMID:26563581

  18. Vibrational states of tetrahedral molecular species in electric fields. A theoretical model for quantitative description of the latent symmetry effects in vibrational spectroscopy of matrix isolated tetrahedral species.

    PubMed

    Pejov, Ljupco; Ivanovski, Gjorgji; Petrusevski, Vladimir M

    2004-11-01

    A theoretical model that enables a quantitative description of latent symmetry effects in the case of matrix isolated tetrahedral species is developed. Several particular cases are considered, that are of special interest from vibrational spectroscopic viewpoint. It is shown that the observed appearances of the IR spectra of various XY4n- anions isomorphously isolated in solid matrices may be systematically explained in terms of the orientation of the effective local crystalline field vector. The model also principally enables calculation of the magnitude of the effective local homogeneous field vector as well as its direction with respect to the symmetry elements of the dopant species, and it can be successively corrected accounting for the field non-homogeneity. Also, a solid theoretical basis is for the first time presented for the significantly smaller site group splitting of the nu4 modes of dopant XY4n- species in comparison to the splitting of nu3 ones, which is often observed in the IR spectra. However, the presented approach has potentially a much wider applicability, as it in facts considers the vibrational states of tetrahedral molecular species in electric fields, which may be of a different origin, for example, electrodes in electrochemical systems, external fields in Stark-type spectroscopies, etc. PMID:15477164

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

    PubMed

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

    1996-07-20

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

  20. 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)

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

    1996-07-01

    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.

  1. 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

    Hsu, Li-Jen; Alwahabi, Zeyad T; Nathan, Graham J; Li, Yu; Li, Z S; Aldén, Marcus

    2011-06-01

    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 φ = 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 φ = 1.149 was found to be 15.1 and 45.3 ppm, respectively. For the case of φ = 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

  2. [Quantitative Measurement of Equivalence Ratios of Methane/Air Mixture by Laser-Induced Breakdown Spectroscopy: the Effects of Detector Gated Mode and Laser Wavelength].

    PubMed

    Zuo, Peng; Li, Bo; Yan, Bei-bei; Li, Zhong-shan; Yao, Ming-fa

    2015-11-01

    Laser-induced breakdown spectroscopy (LIBS) has been increasingly used in combustion diagnostics as a novel spectral analysis method in recent years. The quantitative local equivalence ratio of methane/air mixture is determined by LIBS using different emission intensity ratios of H/O and H/N. The comparison between calibration curves of H₆₅₆/O₇₇₇ and H₆₅₆/N₇₄₆ is performed in gated mode, which shows that H₆₅₆/O₇₇₇ can achieve better prediction accuracy and higher sensitivity. More spectral intensity ratios (H₆₅₆/O₇₇₇, H₆₅₆/N₅₀₀⁺, H₆₅₆/N₅₆₇ and H₆₅₆/N₇₄₆) can be used to make calibration measurements in ungated mode and H₆₅₆/O₇₇₇ is also tested best among them. The comparison between gated and ungated detection modes shows that gated mode offers better accuracy and precision. In addition, the effects of different laser wavelengths (1064, 532 and 355 nm) on LIBS spectra and calibration curves are investigated with laser focal point size and laser fluence kept constant. The results show that with longer laser wavelength, the peak intensity and SNR of H, O and N lines increase, as well as the slope of calibration curve of H₆₅₆/O₇₇₇. Among these three wavelengths, 1064 nm laser is best suited to measure the equivalence ratio of CH₄/air mixture by LIBS. The experimental results are explained in terms of plasma electron density and temperature, which have a significant impact on the emission intensity and the partition function of hydrogen and oxygen, respectively. PMID:26978894

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

    PubMed

    Peerapattana, Jomjai; Otsuka, Kuniko; Otsuka, Makoto

    2013-07-01

    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

  4. Quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy: 2. Application to compacted fine-grained mineral mixtures and assessment of applicability of partial least squares methods

    NASA Astrophysics Data System (ADS)

    Pan, C.; Rogers, A. D.; Thorpe, M. T.

    2015-11-01

    Fine-grained sedimentary deposits on planetary surfaces require quantitative assessment of mineral abundances in order to better understand the environments in which they formed. One way that planetary surface mineralogy is commonly assessed is through thermal emission (~6-50 µm) spectroscopy. To that end, we characterized the TIR spectral properties of compacted, very fine-grained mineral mixtures of oligoclase, augite, calcite, montmorillonite, and gypsum. Nonnegative linear least squares minimization (NNLS) is used to assess the linearity of spectral combination. A partial least squares (PLS) method is also applied to emission spectra of fine-grained synthetic mixtures and natural mudstones to assess its applicability to fine-grained rocks. The NNLS modeled abundances for all five minerals investigated are within ±10% of the known abundances for 39% of the mixtures, showing the relationships between known and modeled abundance follow nonlinear curves. The poor performance of NNLS is due to photon transmission through small grains over portions of the wavelength range and multiple reflections in the volume. The PLS method was able to accurately recover the known abundances (to within ±10%) for 78-90% of synthetic mixtures and for 85% of the mudstone samples chosen for this study. The excellent agreement between known and modeled abundances is likely due to high absorption coefficients over portions of the thermal infrared (TIR) spectral range, and thus, combinations are linear over portions of the range. PLS can be used to recover abundances from very fine-grained rocks from TIR measurements and could potentially be applied to landed or orbital TIR observations.

  5. Biosynthesis of Fluorinated Analogs of Drugs Using Human Cytochrome P450 Enzymes Followed by Deoxyfluorination and Quantitative Nuclear Magnetic Resonance Spectroscopy to Improve Metabolic Stability.

    PubMed

    Obach, R Scott; Walker, Gregory S; Brodney, Michael A

    2016-05-01

    Replacement of hydrogen with fluorine is a useful drug design strategy when decreases in cytochrome P450 (P450) metabolic lability are needed. In this paper, a facile two-step method of inserting fluorine into metabolically labile sites of drug molecules is described that utilizes less than 1 mg of starting material and quantitative NMR spectroscopy to ascertain the structures and concentrations of products. In the first step, hydroxyl metabolites are biosynthesized using human P450 enzymes, and in the second step these metabolites are subjected to deoxyfluorination using diethylaminosulfur trifluoride (DAST). The method is demonstrated using midazolam, celecoxib, ramelteon, and risperidone as examples and CYP3A5, 2C9, 1A2, and 2D6 to catalyze the hydroxylations. The drugs and their fluoro analogs were tested for metabolic lability. 9-Fluororisperidone and 4'-fluorocelecoxib were 16 and 4 times more metabolically stable than risperidone and celecoxib, respectively, and 2-fluororamelteon and ramelteon were metabolized at the same rate. 1'-Fluoromidazolam was metabolized at the same rate as midazolam by CYP3A4 but was more stable in CYP3A5 incubations. The P450-catalyzed sites of metabolism of the fluorine-containing analogs were determined. Some of the metabolites arose via metabolism at the fluorine-substituted carbon, wherein the fluorine was lost to yield aldehydes. In summary, this method offers an approach whereby fluorine can be substituted in metabolically labile sites, and the products can be tested to determine whether an enhancement in metabolic stability was obtained. PMID:26921388

  6. Chiroptical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gurst, Jerome E.

    1995-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Litvin, Valentina A.; Minaev, Boris F.

    2013-05-01

    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.

  8. UV-Vis Reflection-Absorption Spectroscopy at air-liquid interfaces.

    PubMed

    Rubia-Payá, Carlos; de Miguel, Gustavo; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2015-11-01

    UV-Visible Reflection-Absorption Spectroscopy (UVRAS) technique is reviewed with a general perspective on fundamental and applications. UVRAS is formally identical to IR Reflection-Absorption Spectroscopy (IRRAS), and therefore, the methodology developed for this IR technique can be applied in the UV-visible region. UVRAS can be applied to air-solid, air-liquid or liquid-liquid interfaces. This review focuses on the use of UVRAS for studying Langmuir monolayers. We introduce the theoretical framework for a successful understanding of the UVRAS data, and we illustrate the usage of this data treatment to a previous study from our group comprising an amphiphilic porphyrin. For ultrathin films with a thickness of few nm, UVRAS produces positive or negative bands when p-polarized radiation is used, depending on the incidence angle and the orientation of dipole absorption. UVRAS technique provides highly valuable information on tilt of chromophores at the air-liquid interface, and moreover allows the determination of optical parameters. We propose UVRAS as a powerful technique to investigate the in situ optical properties of Langmuir monolayers. PMID:26385430

  9. Honeywell's Compact, Wide-angle Uv-visible Imaging Sensor

    NASA Technical Reports Server (NTRS)

    Pledger, D.; Billing-Ross, J.

    1993-01-01

    Honeywell is currently developing the Earth Reference Attitude Determination System (ERADS). ERADS determines attitude by imaging the entire Earth's limb and a ring of the adjacent star field in the 2800-3000 A band of the ultraviolet. This is achieved through the use of a highly nonconventional optical system, an intensifier tube, and a mega-element CCD array. The optics image a 30 degree region in the center of the field, and an outer region typically from 128 to 148 degrees, which can be adjusted up to 180 degrees. Because of the design employed, the illumination at the outer edge of the field is only some 15 percent below that at the center, in contrast to the drastic rolloffs encountered in conventional wide-angle sensors. The outer diameter of the sensor is only 3 in; the volume and weight of the entire system, including processor, are 1000 cc and 6 kg, respectively.

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

    ERIC Educational Resources Information Center

    Altemose, Ines R.

    1986-01-01

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

  11. Identification and quantitative determination of eudesmane-type acids from the essential oil of Dittrichia viscosa sp. viscosa using 13C-NMR spectroscopy.

    PubMed

    Blanc, Marie-Cécile; Bradesi, Pascale; Casanova, Joseph

    2005-01-01

    A procedure that allows the identification and quantitative determination of eudesmane-type acids in the acidic part of the essential oil of Dittrichia viscosa sp. viscosa is described. The method involves the computer-aided analysis of the 13C-NMR spectrum of the mixture without the requirement of previous separation or derivatisation. The quantitative procedure was verified with costic acid standard and applied to three other acids which possess the same eudesmane framework. PMID:15997846

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

    NASA Astrophysics Data System (ADS)

    Poldi, G.; Caglio, S.

    2013-06-01

    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.

  13. 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)

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

    1989-01-01

    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.

  14. A quantitative and qualitative method to control chemotherapeutic preparations by Fourier transform infrared-ultraviolet spectrophotometry.

    PubMed

    Dziopa, Florian; Galy, Guillaume; Bauler, Stephanie; Vincent, Benoit; Crochon, Sarah; Tall, Mamadou Lamine; Pirot, Fabrice; Pivot, Christine

    2013-06-01

    Chemotherapy products in hospitals include a reconstitution step of manufactured drugs providing an adapted dosage to each patient. The administration of highly iatrogenic drugs raises the question of patients' safety and treatment efficiency. In order to reduce administration errors due to faulty preparations, we introduced a new qualitative and quantitative routine control based on Fourier Transform Infrared (FTIR) and UV-Visible spectrophotometry. This automated method enabled fast and specific control for 14 anticancer drugs. A 1.2 mL sample was used to assay and identify each preparation in less than 90 sec. Over a two-year period, 9370 controlled infusion bags showed a 1.49% nonconformity rate, under 15% tolerance from the theoretical concentration and 96% minimum identification matching factor. This study evaluated the reliability of the control process, as well as its accordance to chemotherapy deliverance requirements. Thus, corrective measures were defined to improve the control process. PMID:23014899

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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.

  16. Quantitative genetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The majority of economically important traits targeted for cotton improvement are quantitatively inherited. In this chapter, the current state of cotton quantitative genetics is described and separated into four components. These components include: 1) traditional quantitative inheritance analysis, ...

  17. A quantitative differentiation method for plastic bags by infrared spectroscopy, thickness measurement and differential scanning calorimetry for tracing the source of illegal drugs.

    PubMed

    Causin, Valerio; Marega, Carla; Carresi, Pietro; Schiavone, Sergio; Marigo, Antonio

    2006-12-20

    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 variability existing in grocery bags, even though they are mass produced, was shown, confirming that these items can be useful in tracing the source of illicit drug doses. PMID:16431052

  18. Quantitative determination of combustion intermediates with cavity ring-down spectroscopy: systematic study in propene flames near the soot-formation limit.

    PubMed

    Schocker, Alexander; Kohse-Höinghaus, Katharina; Brockhinke, Andreas

    2005-11-01

    Cavity ring-down spectroscopy (CRDS) was applied in several fuel-rich, one-dimensional, premixed C3H6/O2/Ar flames at 50 mbars (37.5 torr) to measure absolute OH, HCO, and 1CH2 concentration as well as temperature as a function of stoichiometry. Although these flames near the sooting limit present a complex chemical environment, significant spectral interferences were found to be absent. Specific aspects of the CRDS technique for measurement of temperature and radical concentration profiles are discussed; and the results are analyzed in comparison with flame model simulations. PMID:16270555

  19. Spectrochemistry of solutions—XVIII. Infrared spectroscopy of solutions of electrolytes in liquid ammonia: A new pressure cell and its use in the quantitative determination of thiocyanate

    NASA Astrophysics Data System (ADS)

    Gans, Peter; Gill, J. Bernard; MacInnes, Yvonne M.; Reyner, Colin

    A cell and solution handling system is described which enables i.r. spectra to be obtained for solutions in liquid ammonia, or other condensed gases, at pressures in excess of atmospheric at ambient temperature. Its use, together with a ratio-recording spectrometer, in obtaining quantitative spectroscopic data from dilute solutions of sodium thiocyanate in liquid ammonia by computer subtractions of solution and solvent spectra is illustrated. The applicability of the procedure to high quality determinations of the concentrations of dissolved solutes is demonstrated.

  20. Potential of far-ultraviolet absorption spectroscopy as a highly sensitive qualitative and quantitative analysis method for polymer films, part I: classification of commercial food wrap films.

    PubMed

    Sato, Harumi; Higashi, Noboru; Ikehata, Akifumi; Koide, Noriko; Ozaki, Yukihiro

    2007-07-01

    The aim of the present study is to propose a totally new technique for the utilization of far-ultraviolet (UV) spectroscopy in polymer thin film analysis. Far-UV spectra in the 120-300 nm region have been measured in situ for six kinds of commercial polymer wrap films by use of a novel type of far-UV spectrometer that does not need vacuum evaporation. These films can be straightforwardly classified into three groups, polyethylene (PE) films, polyvinyl chloride (PVC) films, and polyvinylidene chloride (PVDC) films, by using the raw spectra. The differences in the wavelength of the absorption band due to the sigma-sigma* transition of the C-C bond have been used for the classification of the six kinds of films. Using this method, it was easy to distinguish the three kinds of PE films and to separate the two kinds of PVDC films. Compared with other spectroscopic methods, the advantages of this technique include nondestructive analysis, easy spectral measurement, high sensitivity, and simple spectral analysis. The present study has demonstrated that far-UV spectroscopy is a very promising technique for polymer film analysis. PMID:17697474

  1. Quantitative Ultrasound for Staging of Hepatic Steatosis in Patients on Home Parenteral Nutrition Validated with Magnetic Resonance Spectroscopy: A Feasibility Study.

    PubMed

    Weijers, Gerrit; Wanten, Geert; Thijssen, Johan M; van der Graaf, Marinette; de Korte, Chris L

    2016-03-01

    Patients on home parenteral nutrition are at risk for developing liver dysfunction, which is due partly to the accumulation of lipids in the liver (steatosis) and may progress to end-stage liver disease with overt liver failure. Therefore, a timely diagnosis with easy access to repeated assessment of the degree of liver steatosis is of great importance. A pilot study was performed in 14 patients on long-term home parenteral nutrition using the computer-aided ultrasound method. Ultrasound radio frequency data were acquired using a phased array transducer and were converted into conventional B-mode images. All patients were subjected to proton magnetic resonance spectroscopy measurement of liver fat content for reference. Computer-aided ultrasound parameters similar to those in a previous validation study in cows revealed significant correlations with fat content measured by magnetic resonance spectroscopy. The most significant parameters were the residual attenuation coefficient (R = 0.95, p < 0.001) and the lateral speckle size (R = 0.77, p = 0.021). These findings indicate the potential usefulness of computer-aided ultrasound for staging of hepatic steatosis. PMID:26712418

  2. 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)

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

    2010-07-01

    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.

  3. A quantitative study of the carbon impurity production mechanisms from an inertial limiter in Tore Supra as determined by visible spectroscopy

    SciTech Connect

    Tobin, S.J.; Kammash, T.; Hogan, J.T.

    1995-12-01

    In a steady-state tokamak, impurity production and transport from plasma facing components will have to be controlled. Recent results from several divertor tokamaks suggest the importance of chemical sputtering as an impurity production mechanism. However, since impurity production is minimized in high recycling divertor configurations, the quantitative characterization of impurity generation is more difficult than in the high heat flux environment of a limiter configuration. A quantitative study of the role of temperature dependent sputtering mechanisms on the outboard limiter in Tore Supra was performed. The methane flux proved to be significantly reduced above surface temperatures of 1,100 C and negligible above 1,300 C. The peak in the methane yield as a function of surface temperature is consistent with lab results. It was determined that chemical sputtering (early in the shot) had a small, to negligible, impact on the C{sup +} flux; while RES (late in the shot) had a strong impact on the C{sup +} flux. However, from the Z{sub eff} measurements, it was concluded that neither process contributed to the core carbon content.

  4. Qualitative and quantitative determination by Raman spectroscopy of different sulphur oxoacid anions, existing in equilibrium in oxidized leach liquors, produced by desulphurization of flue gases

    NASA Astrophysics Data System (ADS)

    Milićev, S.; Stergaršek, A.

    1989-01-01

    Complex solution equilibria in leach liquors obtained by some of the usual procedures of absorption and oxidation by air of SO 2 in flue gases, are analysed easily and rapidly by Raman spectroscopy. The presence of SO 2-4, HSO -4, S 2O 2-6 and S 4O 2-6 ions is established. Proportionality constants of the simple linear dependence of molar concentrations on relative intensity of the characteristic Raman bands for these species are determined. No calibration curve within the examined concentration range (SO 2-4:0.01-1.25 M; HSO -4:0.01-0.07 M; S 2O 2-6:0.002-0.5 M; S 4O 2-6:0.002-0.1 M) is needed, but the determined constants are not transferable to different experimental conditions or different instruments. Relative standard deviations are between 0.04 and 0.07.

  5. Quantitative Determination of Density of Ground State Atomic Oxygen from Both TALIF and Emission Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

    NASA Astrophysics Data System (ADS)

    Marchal, F.; Yousfi, M.; Merbahi, N.; Wattieaux, G.; Piquemal, A.

    2016-03-01

    Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave (MW) resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence (TALIF) using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy (OES). In this case, we compared the spectra intensities of a specific atomic oxygen line (844 nm) and the closest wavelength xenon line (823 nm). The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon (1% Xe) of this chemically inert gas inside the air while a further small quantity of H2 (2%) is also added in the mixture in order to collect OH(A-X) and NH(A-X) spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09×1017±0.2×1017 cm-3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×1017 cm-3.

  6. Transcriptomic and Metabolomic Differentiation of Breast Cancers: Progression and Therapy Response via Magnetic Resonance Spectroscopy and Quantitative Expression Profiling in the Choline pathway

    PubMed Central

    Morse, David L.; Carroll, Danielle; Day, Sam; Gray, Heather; Sadarangani, Pooja; Murthi, Shiva; Job, Constantin; Baggett, Brenda; Raghunand, Natarajan; Gillies, Robert J.

    2014-01-01

    Tumor choline metabolites have potential for use as diagnostic indicators of breast cancer progression and can be non-invasively monitored in vivo by magnetic resonance spectroscopy. Both a 31P MR visible phosphomonoester peak (~3.9 ppm) and a total choline metabolite peak (~3.2 ppm) detected by 1H MRS are elevated in human breast tumors. As determined by tumor extract studies, the principle diagnostic component of these peaks is phosphocholine (PCho), the biosynthetic precursor to the membrane phospholipid, phosphatidylcholine (PtdCho). In extracts of human breast cells, PCho and the PtdCho breakdown product, glycerophosphocholine, are incrementally increased in cell lines of increasing metastatic potential. The ability to resolve and quantify PCho in vivo would improve the precision of this putative diagnostic tool. Additionally, determining the biochemical mechanisms underlying these metabolic perturbations will improve the understanding of metastatic cancer and could suggest potential molecular targets for drug development. Reported herein is the in vivo resolution and quantification of PCho in a breast cancer xenograft model in SCID mice via image-guided 31P MR spectroscopy, localized to small voxels. Also reported is the quantification of cytosolic and lipid metabolites in breast cancer cells of increasing cancer progression, and the identification of metabolites that differ amongst cell lines by degree of cancer aggressiveness. These metabolic differences are correlated with differences in expression of genes of the choline metabolic pathway. Gene expression changes following taxane therapy are also correlated with previously reported changes in choline metabolites following the same therapy in the same tumor model. Biochemical models explaining the metabolic changes are discussed. PMID:19016452

  7. Improvement of the inverse-gated-decoupling sequence for a faster quantitative analysis of various samples by 13C NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Giraudeau, Patrick; Baguet, Evelyne

    2006-05-01

    The inverse-gated-decoupling sequence enables quantitative 1H decoupled 13C spectra to be obtained. We modified this sequence so as to obtain the same result in less time for molecules containing carbons with various relaxation properties. For that, we determined the optimal 13C longitudinal-magnetization initial value for a faster relaxation while 1H decoupler is stopped. This value can be calculated precisely via the nuclear Overhauser effects, the longitudinal relaxation times, together with the determination of the relaxation rate constants of carbons while 1H are out of equilibrium. A supplementary delay of 1H decoupling and/or a series of selective pulses applied at the beginning of the recovery delay allow an acceleration of 13C longitudinal relaxation. We applied this method to the molecule of vanillin. The simultaneous quantification of all carbons was carried out with a recovery delay divided by two compared to the usual sequence.

  8. Application of a series of artificial neural networks to on-site quantitative analysis of lead into real soil samples by laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    Artificial neural networks were applied to process data from on-site LIBS analysis of soil samples. A first artificial neural network allowed retrieving the relative amounts of silicate, calcareous and ores matrices into soils. As a consequence, each soil sample was correctly located inside the ternary diagram characterized by these three matrices, as verified by ICP-AES. Then a series of artificial neural networks were applied to quantify lead into soil samples. More precisely, two models were designed for classification purpose according to both the type of matrix and the range of lead concentrations. Then, three quantitative models were locally applied to three data subsets. This complete approach allowed reaching a relative error of prediction close to 20%, considered as satisfying in the case of on-site analysis.

  9. Origin of the Reversible Thermochromic Properties of Polydiacetylenes Revealed by Ultrafast Spectroscopy.

    PubMed

    Baek, Junwoo; Joung, Joonyoung F; Lee, Songyi; Rhee, Hanju; Kim, Myung Hwa; Park, Sungnam; Yoon, Juyoung

    2016-01-21

    Polydiacetylenes (PDAs) with thermochromic properties undergo colorimetric transitions when the external temperature is varied. This capability has the potential to enable these materials to be used as temperature sensors. These thermochromic properties of PDAs stem from their temperature-dependent optical properties. In this work, we studied the temperature-dependent optical properties of Bis-PDA-Ph, which exhibits reversible thermochromic properties, and PCDA-PDA, which exhibits irreversible thermochromic properties, by UV-visible absorption and femtosecond transient absorption spectroscopy. Our results indicate that the electronic relaxation of PDAs occurs via an intermediate state in cases where the material exhibits reversible thermochromic properties, whereas the excited PDAs relax directly back to the ground state when irreversible thermochromic properties are observed. The existence of this intermediate state in the electronic relaxation of PDAs thus plays an important role in determining their thermochromic properties. These results are very important for both understanding and strategically modulating the thermochromic properties of PDAs. PMID:26719954

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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).

  11. [Application of near infrared spectroscopy combined with particle swarm optimization based least square support vactor machine to rapid quantitative analysis of Corni Fructus].

    PubMed

    Liu, Xue-song; Sun, Fen-fang; Jin, Ye; Wu, Yong-jiang; Gu, Zhi-xin; Zhu, Li; Yan, Dong-lan

    2015-12-01

    A novel method was developed for the rapid determination of multi-indicators in corni fructus by means of near infrared (NIR) spectroscopy. Particle swarm optimization (PSO) based least squares support vector machine was investigated to increase the levels of quality control. The calibration models of moisture, extractum, morroniside and loganin were established using the PSO-LS-SVM algorithm. The performance of PSO-LS-SVM models was compared with partial least squares regression (PLSR) and back propagation artificial neural network (BP-ANN). The calibration and validation results of PSO-LS-SVM were superior to both PLS and BP-ANN. For PSO-LS-SVM models, the correlation coefficients (r) of calibrations were all above 0.942. The optimal prediction results were also achieved by PSO-LS-SVM models with the RMSEP (root mean square error of prediction) and RSEP (relative standard errors of prediction) less than 1.176 and 15.5% respectively. The results suggest that PSO-LS-SVM algorithm has a good model performance and high prediction accuracy. NIR has a potential value for rapid determination of multi-indicators in Corni Fructus. PMID:27169290

  12. 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)

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

    2014-03-01

    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 Δ[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.

  13. Laser-induced breakdown spectroscopy technique for quantitative analysis of aqueous solution using matrix conversion based on plant fiber spunlaced nonwovens.

    PubMed

    Chen, Chenghan; Niu, Guanghui; Shi, Qi; Lin, Qingyu; Duan, Yixiang

    2015-10-01

    In the present work, laser-induced breakdown spectroscopy (LIBS) was applied to detect concentrations of chromium and nickel in aqueous solution in the form of matrix conversion using plant fiber spunlaced nonwovens as a solid-phase support, which can effectively avoid the inherent difficulties such as splashing, a quenching effect, and a shorter plasma lifetime during the liquid LIBS analysis. Drops of the sample solution were transferred to the plant fiber spunlaced nonwovens surface and uniformly diffused from the center to the whole area of the substrate. Owing to good hydrophilicity, the plant fiber spunlaced nonwovens can hold more of the liquid sample, and the surface of this material never wrinkles after being dried in a drying oven, which can effectively reduce the deviation during the LIBS analysis. In addition, the plant fiber spunlaced nonwovens used in the present work are relatively convenient and low cost. Also, the procedure of analysis was simple and fast, which are the unique features of LIBS technology. Therefore, this method has potential applications for practical and in situ analyses. To achieve sensitive elemental detection, the optimal delay time in this experiment was investigated. Under the optimized condition, the limits of detection for Cr and Ni are 0.7 and 5.7  μg·mL(-1), respectively. The results obtained in the present study show that the matrix conversion method is a feasible option for analyzing heavy metals in aqueous solutions by LIBS technology. PMID:26479603

  14. Quantitative Analysis of Plutonium Content in Particles Collected from a Certified Reference Material by Total Nuclear Reaction Energy (Q Value) Spectroscopy

    NASA Astrophysics Data System (ADS)

    Croce, M. P.; Hoover, A. S.; Rabin, M. W.; Bond, E. M.; Wolfsberg, L. E.; Schmidt, D. R.; Ullom, J. N.

    2016-03-01

    Microcalorimeters with embedded radioisotopes are an emerging category of sensor with advantages over existing methods for isotopic analysis of trace-level nuclear materials. For each nuclear decay, the energy of all decay products captured by the absorber (alpha particles, gamma rays, X-rays, electrons, daughter nuclei, etc.) is measured in one pulse. For alpha-decaying isotopes, this gives a measurement of the total nuclear reaction energy (Q value) and the spectra consist of well-separated, narrow peaks. We have demonstrated a simple mechanical alloying process to create an absorber structure consisting of a gold matrix with small inclusions of a radioactive sample. This absorber structure provides an optimized energy thermalization environment, resulting in high-resolution spectra with minimal tailing. We have applied this process to the analysis of particles collected from the surface of a plutonium metal certified reference material (CRM-126A from New Brunswick Laboratory) and demonstrated isotopic analysis by microcalorimeter Q value spectroscopy. Energy resolution from the Gaussian component of a Bortels function fit was 1.3 keV FWHM at 5244 keV. The collected particles were integrated directly into the detector absorber without any chemical processing. The ^{238} Pu/^{239} Pu and ^{240} Pu/^{239} Pu mass ratios were measured and the results confirmed against the certificate of analysis for the reference material. We also demonstrated inter-element analysis capability by measuring the ^{241} Am/^{239} Pu mass ratio.

  15. Non-Complexing Anions for Quantitative Speciation Studies Using Raman Spectroscopy in Fused Silica High-Pressure Optical Cells Under Hydrothermal Conditions.

    PubMed

    Applegarth, Lucas M S G A; Alcorn, Christopher; Bissonette, Katherine; Nol, John; Tremaine, Peter R

    2015-08-01

    This paper reports methods for obtaining time-dependent reduced isotropic Raman spectra of aqueous species in quartz capillary high-pressure optical cells under hydrothermal conditions, as a means of determining quantitative speciation in hydrothermal fluids. The methods have been used to determine relative Raman scattering coefficients and to examine the thermal decomposition kinetics of the non-complexing anions bisulfate (HSO4(-)), perchlorate (CIO4(-)), perrhenate (ReO4(-)), and trifluoromethanesulfonate, or "triflate" (CF3SO3(-)) in acidic and neutral solutions at temperatures up to 400C and 30 MPa. Arrhenius expressions for calculating the thermal decomposition rate constants are also reported. Thermal stabilities in the acidic solutions followed the order HSO4(-) (stable) > ReO4(-) > CIO4(-) > CF3SO3(-), with half-lives (t1/2) > 7 h at 300C. In neutral solutions, the order was HSO4(-) (stable) > CF3SO3(-) > ReO4(-) > CIO4(-), with t1/2 > 8 h at 350C. CF3SO3(-) was extremely stable in neutral solutions, with t1/2 > 11 h at 400C. PMID:26162934

  16. Change of choline compounds in sodium selenite-induced apoptosis of rats used as quantitative analysis by in vitro 9.4T MR spectroscopy

    PubMed Central

    Cao, Zhen; Wu, Lin-Ping; Li, Yun-Xia; Guo, Yu-Bo; Chen, Yao-Wen; Wu, Ren-Hua

    2008-01-01

    AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar rats were randomly divided into two groups. The rats in the treatment group were intraperitoneally injected with sodium selenite and the control group with distilled water. All rats were sacrificed and the livers were dissected. 1H-MRS data were collected using in vitro 9.4T high resolution magnetic resonance spectrometer. Spectra were processed using XWINNMR and MestRe-c 4.3. HE and TUNEL staining was employed to detect and confirm the change of liver cells. RESULTS: Good 1H-MR spectra of perchloric acid extract from liver tissue of rats were obtained. The conventional metabolites were detected and assigned. Concentrations of different ingredient choline compounds in treatment group vs control group were as follows: total choline compounds, 5.08 0.97 mmol/L vs 3.81 1.16 mmol/L (P = 0.05); and free choline, 1.07 0.23 mmol/L vs 0.65 0.20 mmol/L (P = 0.00). However, there was no statistical significance between the two groups. The hepatic sinus and cellular structure of hepatic cells in treatment group were abnormal. Apoptosis of hepatic cells was confirmed by TUNEL assay. CONCLUSION: High dose selenium compounds can cause the rat liver lesion and induce cell apoptosis in vivo. High resolution 1H-MRS in vitro can detect diversified metabolism. The changing trend for different ingredient of choline compounds is not completely the same at early period of apoptosis. PMID:18609715

  17. Qualitative and quantitative spectro-chemical analysis of dates using UV-pulsed laser induced breakdown spectroscopy and inductively coupled plasma mass spectrometry.

    PubMed

    Mehder, A O; Habibullah, Y B; Gondal, M A; Baig, Umair

    2016-08-01

    Laser Induced Breakdown Spectroscopy (LIBS) is demonstrated for the spectral analysis of nutritional and toxic elements present in several varieties of date fruit samples available in the Saudi Arabia market. The method analyzes the optical emission of a test sample when subjected to pulsed laser ablation. In this demonstration, our primary focus is on calcium (Ca) and magnesium (Mg), as nutritional elements, and on chromium (Cr), as a toxic element. The local thermodynamic equilibrium (LTE) condition was confirmed prior to the elemental characterization of date samples to ensure accuracy of the LIBS analysis. This was achieved by measuring parameters associated with the plasma, such as the electron temperature and the electron number density. These plasma parameters aid interpretation of processes such as ionization, dissociation, and excitation occurring in the plasma plume formed by ablating the date palm sample. The minimum detection limit was established from calibration curves that involved plotting the LIBS signal intensity as a function of standard date samples with known concentrations. The concentration of Ca and Mg detected in different varieties of date samples was between 187 and 515 and 35-196mgL(-1) respectively, while Cr concentration measured between 1.72 and 7.76mgL(-1). In order to optimize our LIBS system, we have studied how the LIBS signal intensity depends on the incident laser energy and the delay time. In order to validate our LIBS analysis results, standard techniques such as inductively coupled plasma mass spectrometry (ICP-MS) were also applied on an identical (duplicate) date samples as those used for the LIBS analysis. The LIBS results exhibit remarkable agreement with those obtained from the ICP-MS analysis. In addition, the finger print wavelengths of other elements present in date samples were also identified and are reported here, which has not been previously reported, to the best of our knowledge. PMID:27216665

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

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

    A new approach based on pulsed photoacoustic spectroscopy for non-invasively quantifying tissue chromophore concentrations with high spatial resolution has been developed. The technique is applicable to the quantification of tissue chromophores such as oxyhaemoglobin (HbO2) and deoxyhaemoglobin (HHb) for the measurement of physiological parameters such as blood oxygen saturation (SO2) and total haemoglobin concentration. It can also be used to quantify the local accumulation of targeted contrast agents used in photoacoustic molecular imaging. The technique employs a model-based inversion scheme to recover the chromophore concentrations from photoacoustic measurements. This comprises a numerical forward model of the detected time-dependent photoacoustic signal that incorporates a multiwavelength diffusion-based finite element light propagation model to describe the light transport and a time-domain acoustic model to describe the generation, propagation and detection of the photoacoustic wave. The forward model is then inverted by iteratively fitting it to measurements of photoacoustic signals acquired at different wavelengths to recover the chromophore concentrations. To validate this approach, photoacoustic signals were generated in a tissue phantom using nanosecond laser pulses between 740 nm and 1040 nm. The tissue phantom comprised a suspension of intralipid, blood and a near-infrared dye in which three tubes were immersed. Blood at physiological haemoglobin concentrations and oxygen saturation levels ranging from 2% to 100% was circulated through the tubes. The signal amplitude from different temporal sections of the detected photoacoustic waveforms was plotted as a function of wavelength and the forward model fitted to these data to recover the concentrations of HbO2 and HHb, total haemoglobin concentration and SO2. The performance was found to compare favourably to that of a laboratory CO-oximeter with measurement resolutions of ±3.8 g l-1 (±58 µM) and ±4.4 g l-1 (±68 µM) for the HbO2 and HHb concentrations respectively and ±4% for SO2 with an accuracy in the latter in the range -6%-+7%.

  19. "EASY: A simple tool for simultaneously removing background, deadtime and acoustic ringing in quantitative NMR spectroscopy. Part II: Improved ringing suppression, application to quadrupolar nuclei, cross polarisation and 2D NMR".

    PubMed

    Jaeger, Christian; Hemmann, Felix

    2014-01-01

    A simple experiment for Elimination of Artifacts in NMR SpectroscopY (EASY) was introduced in Part I, and it was shown that NMR probe background signals, spectral distortions due to deadtime effects, and acoustic ringing can be eliminated simultaneously from solid-state NMR spectra. In this Part II, it is shown that acoustic ringing suppression can be improved up to one order of magnitude compared to the original EASY pulse sequence by inserting a delay τ between the two data acquisition scans of the EASY pulse sequence. The achievable ringing suppression depends on the length of this delay and is limited by the spin-lattice relaxation time T1. Furthermore, EASY is considered in conjunction with NMR of quadrupolar nuclei. For strong second-order broadening, EASY can be used to acquire either pure central transition MAS patterns or pure satellite transition NMR spectra. Two further modifications to EASY are introduced. One concerns improved ringing artifact suppression in experiments in which the central transition NMR signal is amplified by Rotor Assisted Population Transfer (RAPT). The second EASY modification enables the acquisition of quantitative NMR spectra if signals with different quadrupole coupling constants are present. In addition, acoustic ringing and (11)B stator signals are removed. Finally, it is demonstrated that the basic idea of EASY for removing ringing artifacts can be realized for heteronuclear one-dimensional and hetero- and homo-nuclear multi-dimensional NMR experiments using extended phase cycling. (15)N{(1)H} CPMAS and (15)N 2D Exchange NMR spectroscopy are considered as examples. PMID:25200102

  20. Quantitative analysis

    PubMed Central

    Nevin, John A.

    1984-01-01

    Quantitative analysis permits the isolation of invariant relations in the study of behavior. The parameters of these relations can serve as higher-order dependent variables in more extensive analyses. These points are illustrated by reference to quantitative descriptions of performance maintained by concurrent schedules, multiple schedules, and signal-detection procedures. Such quantitative descriptions of empirical data may be derived from mathematical theories, which in turn can lead to novel empirical analyses so long as their terms refer to behavioral and environmental events. Thus, quantitative analysis is an integral aspect of the experimental analysis of behavior. PMID:16812400

  1. Influence of the colloidal structure of dairy gels on milk fat fusion behavior: quantification of the liquid fat content by in situ quantitative proton nuclear magnetic resonance spectroscopy (isq (1) H NMR).

    PubMed

    Bouteille, Romain; Perez, Jeanne; Khifer, Farid; Jouan-Rimbaud-Bouveresse, Delphine; Lecanu, Bruno; This, Hervé

    2013-04-01

    Dairy gels (DG), such as yoghurts, contain both solid and liquid fats at the time of consumption, as their temperature rises to anything between 10 and 24 °C after being introduced into the mouth at 4 °C. The mass ratio between solid and liquid fats, which depends on the temperature, impacts the organoleptic properties of DG. As the ordinary methods for determining this ratio can only be applied to samples consisting mainly in fat materials, a fat extraction step needs to be added into the analytical process when applied to DG, which prevents the study of the potential impact of their colloidal structure on milk fat fusion behavior. In situ quantitative proton nuclear magnetic resonance spectroscopy (isq (1) H NMR) was investigated as a method for direct measurements in DG: at temperatures between 20.0 and 70.0 °C, the liquid fat content and the composition of triacylglycerols of the liquid phase (in terms of alkyl chains length) were determined. Spectra of isolated milk fat also enable the quantification of the double bonds of triacylglycerols. Statistical tests showed no significant difference between isolated milk fat and milk fat inside a DG in terms of melting behavior: the fat globule membrane does not seem to have a significant influence on the fat melting behavior. PMID:23464867

  2. The use of multi-element aerosol particles for determining temporal variations in temperature and electron density in laser-induced plasmas in support of quantitative laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Asgill, Michael E.; Groh, Sebastian; Niemax, Kay; Hahn, David W.

    2015-07-01

    Quantitative laser-induced breakdown spectroscopy (LIBS) analysis operates on the assumption that the sample is completely dissociated and diffused within the highly energetic plasma on time-scales of analyte analysis, resulting in analyte emission ideally at the bulk plasma temperature and a signal that is linear with analyte mass concentration. However, recent studies focusing on aerosol analysis have found the heat and mass diffusion rates within laser-induced plasmas to be finite, resulting in particle-rich, locally perturbed areas within the hot bulk plasma. The goal of this study is to observe any related plasma differences, by calculating the bulk and local (i.e. analyte rich regions) plasma temperatures and electron density, to better understand the time frame of equilibrium between the local and bulk plasma properties. This study also seeks to determine whether the presence of large quantities of a matrix element can significantly alter the local plasma conditions, thereby generating matrix effects. We report the temporal profiles of particle-derived species, adding additional insight into the effect of local perturbation of plasma properties, with the conclusion that significant plasma residence (tens of microseconds) is necessary to minimize such effects.

  3. 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)

    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

    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 μ) 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.

  4. In situ infrared emission spectroscopy for quantitative gas-phase measurement under high temperature reaction conditions: an analytical method for methane by means of an innovative small-volume flowing cell.

    PubMed

    Usseglio, Sandro; Thorshaug, Knut; Karlsson, Arne; Dahl, Ivar M; Nielsen, Claus J; Jens, Klaus-J; Tangstad, Elisabeth

    2010-02-01

    We have used infrared emission spectroscopy (IRES) in order to perform in situ studies under flowing gas-phase conditions. When the small-volume cell developed herein is used, we can (1) observe emission spectra from a hot gas-phase sample having an effective volume much less than one milliliter, (2) observe spectra of typical molecular species present, and (3) observe spectra of the more important molecular species down to below 10% and in some cases even as low as 1%. In addition, an analytical method has been derived in order to conduct quantitative studies under typical reaction conditions. We show that simplifications can be made in the data acquisition and handling for a direct linear correlation between band intensity and concentration with only simple background correction. The practical lower limit for methane in the present setup is approximately 0.5-1% v/v depending on the selected temperature. Our data were collected at 500, 600, and 700 degrees C, respectively. The major features of the present cell design are fairly simple and basically formed by a quartz tube (outer diameter=6 mm, inner diameter=4 mm) inside a metal pipe and two tubular ceramic heaters. This simple setup has advantages and attractive features that have extended the application of IRES to new fields and, in particular, for in situ studies of hydrocarbon reactions at different residence times at high temperature. PMID:20149274

  5. Spectroscopy of divertor plasmas

    SciTech Connect

    Isler, R.C.

    1995-12-31

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

  6. On Quantitizing

    PubMed Central

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

    2009-01-01

    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

  7. Ultraviolet Spectroscopy of Asteroid(4) Vesta

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  8. Spectroscopy and chemistry of the atmosphere of Uranus

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  9. 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)

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

    2014-05-01

    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 wat