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Sample records for absolute concentration determination

  1. Absolute determination of local tropospheric OH concentrations

    NASA Technical Reports Server (NTRS)

    Armerding, Wolfgang; Comes, Franz-Josef

    1994-01-01

    Long path absorption (LPA) according to Lambert Beer's law is a method to determine absolute concentrations of trace gases such as tropospheric OH. We have developed a LPA instrument which is based on a rapid tuning of the light source which is a frequency doubled dye laser. The laser is tuned across two or three OH absorption features around 308 nm with a scanning speed of 0.07 cm(exp -1)/microsecond and a repetition rate of 1.3 kHz. This high scanning speed greatly reduces the fluctuation of the light intensity caused by the atmosphere. To obtain the required high sensitivity the laser output power is additionally made constant and stabilized by an electro-optical modulator. The present sensitivity is of the order of a few times 10(exp 5) OH per cm(exp 3) for an acquisition time of a minute and an absorption path length of only 1200 meters so that a folding of the optical path in a multireflection cell was possible leading to a lateral dimension of the cell of a few meters. This allows local measurements to be made. Tropospheric measurements have been carried out in 1991 resulting in the determination of OH diurnal variation at specific days in late summer. Comparison with model calculations have been made. Interferences are mainly due to SO2 absorption. The problem of OH self generation in the multireflection cell is of minor extent. This could be shown by using different experimental methods. The minimum-maximum signal to noise ratio is about 8 x 10(exp -4) for a single scan. Due to the small size of the absorption cell the realization of an open air laboratory is possible in which by use of an additional UV light source or by additional fluxes of trace gases the chemistry can be changed under controlled conditions allowing kinetic studies of tropospheric photochemistry to be made in open air.

  2. Determinants of relative and absolute concentration indices: evidence from 26 European countries

    PubMed Central

    2013-01-01

    Introduction The aim of publicly-provided health care is generally not only to produce health, but also to decrease variation in health by socio-economic status. The aim of this study is to measure to what extent this goal has been obtained in various European countries and evaluate the determinants of inequalities within countries, as well as cross-country patterns with regard to different cultural, institutional and social settings. Methods The data utilized in this study provides information on 440,000 individuals in 26 European countries and stem from The European Union Statistics on Income and Living Conditions (EU-SILC) collected in 2007. As measures of income-related inequality in health both the relative concentration indices and the absolute concentration indices are calculated. Further, health inequality in each country is decomposed into individual-level determinants and cross-country comparisons are made to shed light on social and institutional determinants. Results Income-related health inequality favoring the better-off is observed for all the 26 European countries. In terms of within-country determinants inequality is mainly explained by income, age, education, and activity status. However, the degree of inequality and contribution of each determinant to inequality varies considerably between countries. Aggregate bivariate linear regressions show that there is a positive association between health-income inequality in Europe and public expenditure on education. Furthermore, a negative relationship between health-income inequality and income inequality was found when individual employee cash income was used in the health-concentration measurement. Using that same income measure, health-income inequality was found to be higher in the Nordic countries than in other areas, but this result is sensitive to the income measure chosen. Conclusions The findings indicate that institutional determinants partly explain income-related health inequalities across

  3. Absolute concentration determination of phosphorus metabolites in the Langendorff-perfused rabbit heart by phosphorus-31 nuclear magnetic resonance

    SciTech Connect

    Gard, J.K.

    1984-01-01

    The concentrations of mobile high energy phosphorus metabolites and intracellular pH of Langendorff-perfused rabbit heart have been determined under control and reduced flow conditions. Absolute concentration determination was accomplished by Lorentzian lineshape analysis after development of hexachlorocyclotriphosphazene as an external intensity standard. Hearts were demonstrated to be biochemically and physiologically competent during control perfusion periods and compromised during reduced flow conditions by independent hemodynamic and metabolic measurements coincident with the NMR experiment. Reduction in perfusate flow from 20 mL/min to 5.0 mL/min (25% flow) or 2.5 mL/min (12.5% flow) demonstrated a fall in phosphocreatine and adenosine triphosphate concentrations, a rise in cytosolic inorganic phosphate concentrations, and drops in pH. Subsequent recovery upon reflow was observed. The derived values for the free concentration of ADP were very close to the reported values of the Michaelis constant for respiratory stimulation, implicating a regulatory role for this molecule in cellular respiration. Strong evidence that the creating kinase reaction was in equilibrium in the 25% flow study was seen. The NMR observable correlated closely with myocardial performance and biochemical indices of metabolic function, and supported the use of phosphocreatine as an indicator of current metabolic integrity.

  4. A non-invasive diffuse reflectance calibration-free method for absolute determination of exogenous biochemicals concentration in biological tissues

    NASA Astrophysics Data System (ADS)

    Lappa, Alexander V.; Kulikovskiy, Artem N.; Busarov, Oleg G.

    2014-03-01

    The paper presents a new method for distant non-destructive determination of concentration of light absorbing admixtures in turbid media. In particular, it is intended for non-invasive in vivo control of accumulation in patient tissues of various biochemicals introduced to the patients for chemotherapy, photodynamic therapy or diagnostics. It is require that the admixture absorption spectrum should have a clearly marked peak in the wavelength region where the pure medium one varies regularly. Fluorescence of admixtures is not required. The method uses the local diffuse reflectance spectroscopy with optical fiber probe including one emitting and two reading There are several features in the method: the value to be determined is absolute concentration of admixtures; the method needs no calibration measurements on phantoms; it needs no reference measurements on sample with zero admixture concentration; it uses a two parametric kinetic light propagation model and original algorithms to resolve direct and inverse tasks of radiation transport theory. Experimental testing passed with tissue equivalent phantoms and different admixtures, including a chlorine photosensitizer, showed accuracy under 10% in all cases.

  5. Under proper control, oxidation of proteins with known chemical structure provides an accurate and absolute method for the determination of their molar concentration.

    PubMed

    Guermant, C; Azarkan, M; Smolders, N; Baeyens-Volant, D; Nijs, M; Paul, C; Brygier, J; Vincentelli, J; Looze, Y

    2000-01-01

    Oxidation at 120 degrees C of inorganic and organic (including amino acids, di- and tripeptides) model compounds by K(2)Cr(2)O(7) in the presence of H(2)SO(4) (mass fraction: 0.572), Ag(2)SO(4) (catalyst), and HgSO(4) results in the quantitative conversion of their C-atoms into CO(2) within 24 h or less. Under these stressed, well-defined conditions, the S-atoms present in cysteine and cystine residues are oxidized into SO(3) while, interestingly, the oxidation states of all the other (including the N-) atoms normally present in a protein do remain quite unchanged. When the chemical structure of a given protein is available, the total number of electrons the protein is able to transfer to K(2)Cr(2)O(7) and thereof, the total number of moles of Cr(3+) ions which the protein is able to generate upon oxidation can be accurately calculated. In such cases, unknown protein molar concentrations can thus be determined through straightforward spectrophotometric measurements of Cr(3+) concentrations. The values of molar absorption coefficients for several well-characterized proteins have been redetermined on this basis and observed to be in excellent agreement with the most precise values reported in the literature, which fully assesses the validity of the method. When applied to highly purified proteins of known chemical structure (more generally of known atomic composition), this method is absolute and accurate (+/-1%). Furthermore, it is well adapted to series measurements since available commercial kits for chemical oxygen demand (COD) measurements can readily be adapted to work under the experimental conditions recommended here for the protein assay. PMID:10610688

  6. Absolute Quantification of Individual Biomass Concentrations in a Methanogenic Coculture

    PubMed Central

    2014-01-01

    Identification of individual biomass concentrations is a crucial step towards an improved understanding of anaerobic digestion processes and mixed microbial conversions in general. The knowledge of individual biomass concentrations allows for the calculation of biomass specific conversion rates which form the basis of anaerobic digestion models. Only few attempts addressed the absolute quantification of individual biomass concentrations in methanogenic microbial ecosystems which has so far impaired the calculation of biomass specific conversion rates and thus model validation. This study proposes a quantitative PCR (qPCR) approach for the direct determination of individual biomass concentrations in methanogenic microbial associations by correlating the native qPCR signal (cycle threshold, Ct) to individual biomass concentrations (mg dry matter/L). Unlike existing methods, the proposed approach circumvents error-prone conversion factors that are typically used to convert gene copy numbers or cell concentrations into actual biomass concentrations. The newly developed method was assessed and deemed suitable for the determination of individual biomass concentrations in a defined coculture of Desulfovibrio sp. G11 and Methanospirillum hungatei JF1. The obtained calibration curves showed high accuracy, indicating that the new approach is well suited for any engineering applications where the knowledge of individual biomass concentrations is required. PMID:24949269

  7. Determination of the absolute contours of optical flats

    NASA Technical Reports Server (NTRS)

    Primak, W.

    1969-01-01

    Emersons procedure is used to determine true absolute contours of optical flats. Absolute contours of standard flats are determined and a comparison is then made between standard and unknown flats. Contour differences are determined by deviation of Fizeau fringe.

  8. MAGSAT: Vector magnetometer absolute sensor alignment determination

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.

    1981-01-01

    A procedure is described for accurately determining the absolute alignment of the magnetic axes of a triaxial magnetometer sensor with respect to an external, fixed, reference coordinate system. The method does not require that the magnetic field vector orientation, as generated by a triaxial calibration coil system, be known to better than a few degrees from its true position, and minimizes the number of positions through which a sensor assembly must be rotated to obtain a solution. Computer simulations show that accuracies of better than 0.4 seconds of arc can be achieved under typical test conditions associated with existing magnetic test facilities. The basic approach is similar in nature to that presented by McPherron and Snare (1978) except that only three sensor positions are required and the system of equations to be solved is considerably simplified. Applications of the method to the case of the MAGSAT Vector Magnetometer are presented and the problems encountered discussed.

  9. Behavior of Multiclass Pesticide Residue Concentrations during the Transformation from Rose Petals to Rose Absolute.

    PubMed

    Tascone, Oriane; Fillâtre, Yoann; Roy, Céline; Meierhenrich, Uwe J

    2015-05-27

    This study investigates the concentrations of 54 multiclass pesticides during the transformation processes from rose petal to concrete and absolute using roses spiked with pesticides as a model. The concentrations of the pesticides were followed during the process of transforming the spiked rose flowers from an organic field into concrete and then into absolute. The rose flowers, the concrete, and the absolute, as well as their transformation intermediates, were analyzed for pesticide content using gas chromatography/tandem mass spectrometry. We observed that all the pesticides were extracted and concentrated in the absolute, with the exception of three molecules: fenthion, fenamiphos, and phorate. Typical pesticides were found to be concentrated by a factor of 100-300 from the rose flowers to the rose absolute. The observed effect of pesticide enrichment was also studied in roses and their extracts from four classically phytosanitary treated fields. Seventeen pesticides were detected in at least one of the extracts. Like the case for the spiked samples in our model, the pesticides present in the rose flowers from Turkey were concentrated in the absolute. Two pesticides, methidathion and chlorpyrifos, were quantified in the rose flowers at approximately 0.01 and 0.01-0.05 mg kg(-1), respectively, depending on the treated field. The concentrations determined for the corresponding rose absolutes were 4.7 mg kg(-1) for methidathion and 0.65-27.25 mg kg(-1) for chlorpyrifos. PMID:25942486

  10. Non-invasive quantification of brain glycogen absolute concentration

    PubMed Central

    van Heeswijk, Ruud B.; Xin, Lijing; Laus, Sabrina; Frenkel, Hanne; Lei, Hongxia; Gruetter, Rolf

    2009-01-01

    The only currently available method to measure brain glycogen in vivo is 13C NMR spectroscopy. Incorporation of 13C-labeled glucose (Glc) is necessary to allow glycogen measurement, but might be affected by turnover changes. Our aim was to measure glycogen absolute concentration in the rat brain by eliminating label turnover as variable. The approach is based on establishing an increased, constant 13C isotopic enrichment (IE). 13C-Glc infusion is then performed at the IE of brain glycogen. As glycogen IE cannot be assessed in vivo, we validated that it can be inferred from that of N-acetyl-aspartate IE in vivo: After [1-13C]-Glc ingestion, glycogen IE was 2.2 ± 0.1 fold that of N-acetyl-aspartate (n = 11, R2 = 0.77). After subsequent Glc infusion, glycogen IE equaled brain Glc IE (n = 6, paired t-test, p = 0.37), implying isotopic steady-state achievement and complete turnover of the glycogen molecule. Glycogen concentration measured in vivo by 13C NMR (mean ± SD: 5.8 ± 0.7 μmol/g) was in excellent agreement with that in vitro (6.4 ± 0.6 μmol/g, n = 5). When insulin was administered, the stability of glycogen concentration was analogous to previous biochemical measurements implying that glycogen turnover is activated by insulin. We conclude that the entire glycogen molecule is turned over and that insulin activates glycogen turnover. PMID:19013831

  11. Correlating absolute concentrations of gas-phase species determined by microwave, Fourier transform infrared, and atomic absorption spectroscopies to properties of silicon dioxide films deposited in an electron cyclotron resonance reactor

    NASA Astrophysics Data System (ADS)

    Cornett, Mary Jezl

    Three different gas-phase absorption spectroscopies (microwave, FTIR, and silicon atomic absorption) were used simultaneously during the plasma enhanced chemical vapor deposition of SiO2 and fluorinated SiO 2 films using an ECR deposition reactor. With these spectroscopic techniques, absolute concentrations of a large number of species present in these deposition plasmas were determined. A new ECR system with multiple diagnostic ports on the same horizontal plane, and incorporating an electrostatic chuck, rf-bias, and He-backside cooling, was constructed to facilitate these studies. Correlations to the quality of the resulting films were made using ellipsometry, FTIR, XPS, and wet etch rate techniques. The systems investigated were SiH 4/O2/Ar, SiH4/SiF4/O2 and TEOS/O2 plasmas. The SiH4/O2 plasmas are found to contain less water than previously expected (under our detection limit of 0.1 mTorr). The molecular fragment SiO was monitored as a function of power, pressure, oxygen flow, and argon flow at densities between 3.7 × 109 and 1.3 × 10-11 cm-3 in this system. Silicon atoms were detected at densities between 5.1 × 109 and 5.8 × 1010 cm -3. The decomposition of SiF4 is investigated and is shown to occur at a constant rate of about 98% in pure SiF4/O 2 plasmas. This dissociation rate is enhanced when silane is added. Water and HF are generated in large quantities when SiH4 and SiF 4 are both present in the system, and reach their maximum concentrations at the SiF4/SiH4 ratio where the film quality appears to be the best. Fluorine incorporation into SiOF films result in a consistent decrease in index of refraction values. No SiO molecules were detected in SiH4/SiF4/O2 chemistries (<5 × 10 9 cm-3). Plasmas employing TEOS/O2 chemistries show large concentrations of CO, CO2 and H2O. Larger organic molecules (ethanol, acetaldehyde, methanol, formaldehyde, and formic acid) are also present in these plasmas, totaling about 9% of the species present under most

  12. Multifrequency continuous wave terahertz spectroscopy for absolute thickness determination

    SciTech Connect

    Scheller, Maik; Baaske, Kai; Koch, Martin

    2010-04-12

    We present a tunable multifrequency continuous wave terahertz spectrometer based on two laser diodes, photoconductive antennas, and a coherent detection scheme. The system is employed to determine the absolute thickness of samples utilizing a proposed synthetic difference frequency method to circumvent the 2pi uncertainty known from conventional photomixing systems while preserving a high spatial resolution.

  13. Non-Invasive Method of Determining Absolute Intracranial Pressure

    NASA Technical Reports Server (NTRS)

    Yost, William T. (Inventor); Cantrell, John H., Jr. (Inventor); Hargens, Alan E. (Inventor)

    2004-01-01

    A method is presented for determining absolute intracranial pressure (ICP) in a patient. Skull expansion is monitored while changes in ICP are induced. The patient's blood pressure is measured when skull expansion is approximately zero. The measured blood pressure is indicative of a reference ICP value. Subsequently, the method causes a known change in ICP and measured the change in skull expansion associated therewith. The absolute ICP is a function of the reference ICP value, the known change in ICP and its associated change in skull expansion; and a measured change in skull expansion.

  14. Determination of absolute internal conversion coefficients using the SAGE spectrometer

    NASA Astrophysics Data System (ADS)

    Sorri, J.; Greenlees, P. T.; Papadakis, P.; Konki, J.; Cox, D. M.; Auranen, K.; Partanen, J.; Sandzelius, M.; Pakarinen, J.; Rahkila, P.; Uusitalo, J.; Herzberg, R.-D.; Smallcombe, J.; Davies, P. J.; Barton, C. J.; Jenkins, D. G.

    2016-03-01

    A non-reference based method to determine internal conversion coefficients using the SAGE spectrometer is carried out for transitions in the nuclei of 154Sm, 152Sm and 166Yb. The Normalised-Peak-to-Gamma method is in general an efficient tool to extract internal conversion coefficients. However, in many cases the required well-known reference transitions are not available. The data analysis steps required to determine absolute internal conversion coefficients with the SAGE spectrometer are presented. In addition, several background suppression methods are introduced and an example of how ancillary detectors can be used to select specific reaction products is given. The results obtained for ground-state band E2 transitions show that the absolute internal conversion coefficients can be extracted using the methods described with a reasonable accuracy. In some cases of less intense transitions only an upper limit for the internal conversion coefficient could be given.

  15. Engine performance and the determination of absolute ceiling

    NASA Technical Reports Server (NTRS)

    Diehl, Walter S

    1924-01-01

    This report contains a brief study of the variation of engine power with temperature and pressure. The variation of propeller efficiency in standard atmosphere is obtained from the general efficiency curve which is developed in NACA report no. 168. The variation of both power available and power required are then determined and curves plotted, so that the absolute ceiling may be read directly from any known sea-level value of the ratio of power available to power required.

  16. Determination of absolute structure using Bayesian statistics on Bijvoet differences

    PubMed Central

    Hooft, Rob W. W.; Straver, Leo H.; Spek, Anthony L.

    2008-01-01

    A new probabilistic approach is introduced for the determination of the absolute structure of a compound which is known to be enantiopure based on Bijvoet-pair intensity differences. The new method provides relative probabilities for different models of the chiral composition of the structure. The outcome of this type of analysis can also be cast in the form of a new value, along with associated standard uncertainty, that resembles the value of the well known Flack x parameter. The standard uncertainty we obtain is often about half of the standard uncertainty in the value of the Flack x parameter. The proposed formalism is suited in particular to absolute configuration determination from diffraction data of biologically active (pharmaceutical) compounds where the strongest resonant scattering signal often comes from oxygen. It is shown that a reliable absolute configuration assignment in such cases can be made on the basis of Cu Kα data, and in some cases even with carefully measured Mo Kα data. PMID:19461838

  17. Determination of absolute threshold and just noticeable difference in the sensory perception of pungency.

    PubMed

    Orellana-Escobedo, L; Ornelas-Paz, J J; Olivas, G I; Guerrero-Beltran, J A; Jimenez-Castro, J; Sepulveda, D R

    2012-03-01

    Absolute threshold and just noticeable difference (JND) were determined for the perception of pungency using chili pepper in aqueous solutions. Absolute threshold and JND were determined using 2 alternative forced-choice sensory tests tests. High-performance liquid chromatography technique was used to determine capsaicinoids concentration in samples used for sensory analysis. Sensory absolute threshold was 0.050 mg capsaicinoids/kg sample. Five JND values were determined using 5 reference solutions with different capsaicinoids concentration. JND values changed proportionally as capsaicinoids concentration of the reference sample solutions changed. Weber fraction remained stable for the first 4 reference capsaicinoid solutions (0.05, 0.11, 0.13, and 0.17 mg/kg) but changed when the most concentrated reference capsaicinoids solution was used (0.23 mg/kg). Quantification limit for instrumental analysis was 1.512 mg/kg capsaicinoids. Sensory methods employed in this study proved to be more sensitive than instrumental methods. Practical Application: A better understanding of the process involved in the sensory perception of pungency is currently required because "hot" foods are becoming more popular in western cuisine. Absolute thresholds and differential thresholds are useful tools in the formulation and development of new food products. These parameters may help in defining how much chili pepper is required in a formulated product to ensure a perceptible level of pungency, as well as in deciding how much more chili pepper is required in a product to produce a perceptible increase in its pungency. PMID:22384966

  18. Absolute determination of inelastic mean-free paths and surface excitation parameters by absolute reflection electron energy loss spectrum analysis

    NASA Astrophysics Data System (ADS)

    Nagatomi, T.; Goto, K.

    2005-11-01

    An analytical approach was proposed for simultaneously determining an inelastic mean-free path (IMFP) and a surface excitation parameter (SEP) with absolute units by the analysis of an absolute experimental reflection electron energy loss spectrum. The IMFPs and SEPs in Ni were deduced for electrons of 300 to 3000 eV. The obtained IMFPs were in good agreement with those calculated using the TPP-2M equation. The Chen-type empirical formula was proposed for determining the SEP. The results confirmed the applicability of the present approach for determining the IMFP and SEP for medium-energy electrons.

  19. In situ measurement of leaf chlorophyll concentration: analysis of the optical/absolute relationship.

    PubMed

    Parry, Christopher; Blonquist, J Mark; Bugbee, Bruce

    2014-11-01

    In situ optical meters are widely used to estimate leaf chlorophyll concentration, but non-uniform chlorophyll distribution causes optical measurements to vary widely among species for the same chlorophyll concentration. Over 30 studies have sought to quantify the in situ/in vitro (optical/absolute) relationship, but neither chlorophyll extraction nor measurement techniques for in vitro analysis have been consistent among studies. Here we: (1) review standard procedures for measurement of chlorophyll; (2) estimate the error associated with non-standard procedures; and (3) implement the most accurate methods to provide equations for conversion of optical to absolute chlorophyll for 22 species grown in multiple environments. Tests of five Minolta (model SPAD-502) and 25 Opti-Sciences (model CCM-200) meters, manufactured from 1992 to 2013, indicate that differences among replicate models are less than 5%. We thus developed equations for converting between units from these meter types. There was no significant effect of environment on the optical/absolute chlorophyll relationship. We derive the theoretical relationship between optical transmission ratios and absolute chlorophyll concentration and show how non-uniform distribution among species causes a variable, non-linear response. These results link in situ optical measurements with in vitro chlorophyll concentration and provide insight to strategies for radiation capture among diverse species. PMID:24635697

  20. Measurements of absolute concentrations of NADH in cells using the phasor FLIM method

    PubMed Central

    Ma, Ning; Digman, Michelle A.; Malacrida, Leonel; Gratton, Enrico

    2016-01-01

    We propose a graphical method using the phasor representation of the fluorescence decay to derive the absolute concentration of NADH in cells. The method requires the measurement of a solution of NADH at a known concentration. The phasor representation of the fluorescence decay accounts for the differences in quantum yield of the free and bound form of NADH, pixel by pixel of an image. The concentration of NADH in every pixel in a cell is obtained after adding to each pixel in the phasor plot a given amount of unmodulated light which causes a shift of the phasor towards the origin by an amount that depends on the intensity at the pixel and the fluorescence lifetime at the pixel. The absolute concentration of NADH is obtained by comparison of the shift obtained at each pixel of an image with the shift of the calibrated solution. PMID:27446681

  1. Absolute determination of the neutron source yield using melamine as a neutron detector

    NASA Astrophysics Data System (ADS)

    Ciechanowski, M.; Bolewski, A., Jr.; Kreft, A.

    2015-01-01

    A new approach to absolute determination of the neutron source yield is presented. It bases on the application of melamine (C3H6N6) to neutron detection combined with Monte Carlo simulations of neutron transport. Melamine has the ability to detect neutrons via 14N(n, p)14C reaction and subsequent determination of 14C content. A cross section for this reaction is relatively high for thermal neutrons (1.827 b) and much lower for fast neutrons. A concentration of 14C nuclei created in the irradiated sample of melamine can be reliably measured with the aid of the accelerator mass spectrometry (AMS). The mass of melamine sufficient for this analysis is only 10 mg. Neutron detection is supported by Monte Carlo simulations of neutron transport carried out with the use of MCNP-4C code. These simulations are aimed at computing the probability of 14C creation in the melamine sample per the source neutron. The result of AMS measurements together with results of MCNP calculations enable us to determine the number of neutrons emitted from the source during the irradiation of melamine. The proposed method was applied for determining the neutron emission from a commercial 252Cf neutron source which was independently calibrated. The measured neutron emission agreed with the certified one within uncertainty limits. The relative expanded uncertainty (k=2) of the absolute neutron source yield determination was estimated at 2.6%. Apart from calibration of radionuclide neutron sources the proposed procedure could facilitate absolute yield measurements for more complex sources. Potential applications of this methodology as it is further developed include diagnostics of inertial confinement fusion and plasma-focus experiments, calibration of neutron measurement systems at tokamaks and accelerator-based neutron sources as well as characterization of neutron fields generated in large particle detectors during collisions of hadron beams.

  2. Absolute tracer dye concentration using airborne laser-induced water Raman backscatter

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1981-01-01

    The use of simultaneous airborne-laser-induced dye fluorescence and water Raman backscatter to measure the absolute concentration of an ocean-dispersed tracer dye is discussed. Theoretical considerations of the calculation of dye concentration by the numerical comparison of airborne laser-induced fluorescence spectra with laboratory spectra for known dye concentrations using the 3400/cm OH-stretch water Raman scatter as a calibration signal are presented which show that minimum errors are obtained and no data concerning water mass transmission properties are required when the laser wavelength is chosen to yield a Raman signal near the dye emission band. Results of field experiments conducted with an airborne conical scan lidar over a site in New York Bight into which rhodamine dye had been injected in a study of oil spill dispersion are then indicated which resulted in a contour map of dye concentrations, with a minimum detectable dye concentration of approximately 2 ppb by weight.

  3. Noninvasive imaging of absolute PpIX concentration distribution in nonmelanoma skin tumors at pre-PDT

    NASA Astrophysics Data System (ADS)

    Sunar, Ulas; Rohrbach, Daniel; Morgan, Janet; Zeitouni, Natalie

    2013-03-01

    Photodynamic Therapy (PDT) has proven to be an effective treatment option for nonmelanoma skin cancers. The ability to quantify the concentration of drug in the treated area is crucial for effective treatment planning as well as predicting outcomes. We utilized spatial frequency domain imaging for quantifying the accurate concentration of protoporphyrin IX (PpIX) in phantoms and in vivo. We correct fluorescence against the effects of native tissue absorption and scattering parameters. First we quantified the absorption and scattering of the tissue non-invasively. Then, we corrected raw fluorescence signal by compensating for optical properties to get the absolute drug concentration. After phantom experiments, we used basal cell carcinoma (BCC) model in Gli mice to determine optical properties and drug concentration in vivo at pre-PDT.

  4. Absolute radical densities in etching plasmas determined by broad-band UV absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Cunge, Gilles; Neuilly, François; Sadeghi, Nader

    1998-08-01

    Broad-band UV absorption spectroscopy was used to determine radical densities in reactive gas plasmas generated in a 13.56 MHz capacitively coupled parallel plate reactor. Five radical species were detected: 0963-0252/7/3/021/img1, CF, AlF, 0963-0252/7/3/021/img2 and 0963-0252/7/3/021/img3. Absolute (line-integrated) 0963-0252/7/3/021/img1 densities were determined in 0963-0252/7/3/021/img5 and 0963-0252/7/3/021/img6 plasmas, as were the 0963-0252/7/3/021/img1 vibrational and rotational temperatures in the latter case. In 0963-0252/7/3/021/img5 plasmas the CF radical was also detected, along with the etch products AlF (from the Al powered electrode) and 0963-0252/7/3/021/img2 (when an Si substrate was present). The fraction that 0963-0252/7/3/021/img2 comprises of the total etch products was estimated. Finally, the 0963-0252/7/3/021/img3 dimer was detected in an 0963-0252/7/3/021/img12 plasma in the presence of an Si substrate. This simple technique allows absolute concentrations of many key reactive species to be determined in reactive plasmas, without the need to analyse the complex rotational spectra of these polyatomic molecules.

  5. Using absolute gravimeter data to determine vertical gravity gradients

    USGS Publications Warehouse

    Robertson, D.S.

    2001-01-01

    The position versus time data from a free-fall absolute gravimeter can be used to estimate the vertical gravity gradient in addition to the gravity value itself. Hipkin has reported success in estimating the vertical gradient value using a data set of unusually good quality. This paper explores techniques that may be applicable to a broader class of data that may be contaminated with "system response" errors of larger magnitude than were evident in the data used by Hipkin. This system response function is usually modelled as a sum of exponentially decaying sinusoidal components. The technique employed here involves combining the x0, v0 and g parameters from all the drops made during a site occupation into a single least-squares solution, and including the value of the vertical gradient and the coefficients of system response function in the same solution. The resulting non-linear equations must be solved iteratively and convergence presents some difficulties. Sparse matrix techniques are used to make the least-squares problem computationally tractable.

  6. Accurate determination of absolute carrier-envelope phase dependence using photo-ionization.

    PubMed

    Sayler, A M; Arbeiter, M; Fasold, S; Adolph, D; Möller, M; Hoff, D; Rathje, T; Fetić, B; Milošević, D B; Fennel, T; Paulus, G G

    2015-07-01

    The carrier-envelope phase (CEP) dependence of few-cycle above-threshold ionization (ATI) of Xe is calibrated for use as a reference measurement for determining and controlling the absolute CEP in other interactions. This is achieved by referencing the CEP-dependent ATI measurements of Xe to measurements of atomic H, which are in turn referenced to ab initio calculations for atomic H. This allows for the accurate determination of the absolute CEP dependence of Xe ATI, which enables relatively easy determination of the offset between the relative CEP measured and/or controlled by typical devices and the absolute CEP in the interaction. PMID:26125386

  7. Determination of the Absolute Stereochemistry of Secondary Alcohols: An Advanced Organic Chemistry Experiment for Undergraduate Students.

    ERIC Educational Resources Information Center

    Bandaranayake, Wickramasinghe M.

    1980-01-01

    Describes experiments which can be completed in five four-hour laboratory sessions, including two synthesis (alpha-phenylbutyric and alpha-phenylbutyric acid anhydride) and determining the absolute stereochemistry of secondary alcohols using the synthetic products. (JN)

  8. A Simple Watt Balance for the Absolute Determination of Mass

    ERIC Educational Resources Information Center

    Quinn, Terry; Quinn, Lucas; Davis, Richard

    2013-01-01

    A watt balance is an electromechanical device that allows a mass to be determined in terms of measurable electrical and mechanical quantities, themselves traceable to the fundamental constants of physics. International plans are well advanced to redefine the unit of mass, the kilogram, in terms of a fixed numerical value for the Planck constant. A…

  9. On determining absolute entropy without quantum theory or the third law of thermodynamics

    NASA Astrophysics Data System (ADS)

    Steane, Andrew M.

    2016-04-01

    We employ classical thermodynamics to gain information about absolute entropy, without recourse to statistical methods, quantum mechanics or the third law of thermodynamics. The Gibbs–Duhem equation yields various simple methods to determine the absolute entropy of a fluid. We also study the entropy of an ideal gas and the ionization of a plasma in thermal equilibrium. A single measurement of the degree of ionization can be used to determine an unknown constant in the entropy equation, and thus determine the absolute entropy of a gas. It follows from all these examples that the value of entropy at absolute zero temperature does not need to be assigned by postulate, but can be deduced empirically.

  10. Selective polymer materials: absolute determination of their sorption properties

    NASA Astrophysics Data System (ADS)

    Jakusch, Michael; Mizaikoff, Boris

    2001-02-01

    Several types of selective materials are frequently used in chemical sensors such as natural antibodies, synthetic host substances (calixarenes, cyclodextrines, etc.) molecularly imprinted materials, or conventional polymers. For a systematic development of those materials, their sorption behavior for interesting analyte substances and potentially interfering compounds has to be thoroughly characterized, which can be a time-consuming and error-prone task. Moreover, using the respective sensor principle itself for this characterization an exact relation between the sensor signal and the underlying partition coefficient or sorption isotherm can often not be obtained. In this paper, we present an automated method for the direct determination of polymer/water partition coefficients of volatile organic compounds that consists of an automated fluid handling system, a dedicated partitioning cell and a purge-and-trap gas chromatography (PT-GC) unit. The main application of this novel system is the characterization of layer materials for infrared evanescent wave spectroscopic (IR-EWS) sensors, however an extension to other problems is conceivable. The whole experimental procedure comprising calibration of the GC system, preparation of test solutions, analyte partitioning, sample analysis, as well as the necessary cleaning steps is performed automatically under computer control. Hence, this system can be operated unattendedly, yielding a reasonable throughput with comparatively low expenditure of human labor.

  11. Methods for sperm concentration determination.

    PubMed

    Björndahl, Lars

    2013-01-01

    Proper assessment of the number of spermatozoa is essential not only as an initial step in every clinical infertility investigation [Björndahl et al (2010) A practical guide to basic laboratory andrology, 1st edn. Cambridge University Press, Cambridge] but also when attempting to establish the total sperm production in the testis [Amann (Hum Reprod 25:22-28, 2010); Amann (J Androl 30:626-641, 2009); Amann and Chapman (J Androl 30:642-649, 2009)]. Reliable methods combined with an understanding of the specific physiology involved as well as the main sources of errors related to the assessment of sperm concentration are critical for ensuring accurate concentration determination [Björndahl et al (2010) A practical guide to basic laboratory andrology, 1st edn. Cambridge University Press, Cambridge; World Health Organization (2010) WHO laboratory manual for the examination and processing of human semen. WHO, Geneva]. This chapter therefore focuses on these three aspects. PMID:22992898

  12. Absolute quantitative autoradiography of low concentrations of (/sup 125/I)-labeled proteins in arterial tissue

    SciTech Connect

    Schnitzer, J.J.; Morrel, E.M.; Colton, C.K.; Smith, K.A.; Stemerman, M.B.

    1987-12-01

    We developed a method for absolute quantitative autoradiographic measurement of very low concentrations of (/sup 125/I)-labeled proteins in arterial tissue using Kodak NTB-2 nuclear emulsion. A precise linear relationship between measured silver grain density and isotope concentration was obtained with uniformly labeled standard sources composed of epoxy-embedded gelatin containing glutaraldehyde-fixed (/sup 125/I)-albumin. For up to 308-day exposures of 1 micron-thick tissue sections, background grain densities ranged from about two to eight grains/1000 micron 2, and the technique was sensitive to as little as about one grain/1000 micron 2 above background, which correspond to a radioactivity concentration of about 2 x 10(4) cpm/ml. A detailed statistical analysis of variability was performed and the sum of all sources of variation quantified. The half distance for spatial resolution was 1.7 micron. Both visual and automated techniques were employed for quantitative grain density analysis. The method was illustrated by measurement of in vivo transmural (/sup 125/I)-low-density lipoprotein (( /sup 125/I)-LDL) concentration profiles in de-endothelialized rabbit thoracic aortic wall.

  13. Principles and procedures for determining absolute differential electron-molecule (atom) scattering cross sections

    NASA Technical Reports Server (NTRS)

    Nickel, J. C.; Zetner, P. W.; Shen, G.; Trajmar, S.

    1989-01-01

    Procedures and calibration techniques for measuring the absolute elastic and inelastic differential cross sections (DCS) for electron impact on molecular (atomic) species are described and illustrated by examples. The elastic DCS for the molecule under study is first determined by calibration against helium using the relative flow technique. The second step involves the production of energy-loss spectra for the instrument response function, the unfolding of overlapping inelastic structures and the normalization of inelastic intensities to the elastic cross sections. It is concluded that this method of determining absolute differential electron-molecule (atom) scattering cross sections is generally applicable and provides reliable results.

  14. Determination of the absolute configuration of sialic acids in gangliosides from the sea cucumber Cucumaria echinata.

    PubMed

    Kisa, Fumiaki; Yamada, Koji; Miyamoto, Tomofumi; Inagaki, Masanori; Higuchi, Ryuichi

    2007-07-01

    Enantiomeric pairs of sialic acid, D- and L-NeuAc (N-acetylneuraminic acid), were converted to D- and L-arabinose, respectively, by chemical degradation. Using this method, the absolute configuration of the sialic acid residues, NeuAc and NeuGc (N-glycolylneuraminic acid), in the gangliosides from the sea cucumber Cucumaria echinata was determined to be the D-form. Although naturally occurring sialic acids have been believed to be the D-form on the basis of biosynthetic evidence, this is the first report of the determination of the absolute configuration of the sialic acid residues in gangliosides using chemical methods. PMID:17603199

  15. Spectrofluorimetric determination of aluminum ions via complexation with luteolin in absolute ethanol.

    PubMed

    Sun, Jinyu; Wu, You; Xiao, Dan; Lin, Xia; Li, Hui

    2014-08-01

    An optimized and validated spectrofluorimetric method has been developed for the rapid determination of aluminum in absolute ethanol. The method is based on the chelation of aluminum and luteolin which results in a complex exhibiting an intense emission signal. The characterization of Al-luteolin complex was studied using ultraviolet-visible spectrometry, infrared spectrometry, fluorescence and mass spectrometry. The complex stoichiometry ratio of aluminum:luteolin was 1:2. The fluorescence of the complex was monitored at an emission wavelength of 545 nm with excitation at 518 nm. The linear concentration range was 6.5 × 10(-7) to 4.0 × 10(-5)  M with a correlation coefficient of r = 0.998. The detection limit was 5.0 × 10(-7)  M. The method was appropriately validated and yielded relative standard deviations of < 2.3% (n = 5), which was considered acceptable. The method was successfully applied in the determination of aluminum in river water, skin care products and pharmaceutical samples. PMID:24039003

  16. Chiral liquid chromatography contribution to the determination of the absolute configuration of enantiomers.

    PubMed

    Roussel, Christian; Del Rio, Alberto; Pierrot-Sanders, Johanna; Piras, Patrick; Vanthuyne, Nicolas

    2004-05-28

    The review covers examples in which chiral HPLC, as a source of pure enantiomers, has been combined with classical methods (X-ray, vibrational circular dichroism (VCD), enzymatic resolutions, nuclear magnetic resonance (NMR) techniques, optical rotation, circular dichroism (CD)) for the on- or off-line determination of absolute configuration of enantiomers. Furthermore, it is outlined that chiral HPLC, which associates enantioseparation process and classical purification process, opens new perspectives in the classical determination of absolute configuration by chemical correlation or chemical interconversion methods. The review also contains a discussion about the various approaches to predict the absolute configuration from the retention behavior of the enantiomers on chiral stationary phases (CSPs). Some examples illustrate the advantages and limitations of molecular modeling methods and the use of chiral recognition models. The assumptions underlying some of these methods are critically analyzed and some possible emerging new strategies are outlined. PMID:15214673

  17. Determination of absolute configuration of natural products: theoretical calculation of electronic circular dichroism as a tool

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of absolute configuration (AC) is one of the most challenging features in the structure elucidation of chiral natural products, especially those with complex structures. With revolutionary advancements in the area of quantum chemical calculations of chiroptical spectroscopy over the pa...

  18. Fast, Computer Supported Experimental Determination of Absolute Zero Temperature at School

    ERIC Educational Resources Information Center

    Bogacz, Bogdan F.; Pedziwiatr, Antoni T.

    2014-01-01

    A simple and fast experimental method of determining absolute zero temperature is presented. Air gas thermometer coupled with pressure sensor and data acquisition system COACH is applied in a wide range of temperature. By constructing a pressure vs temperature plot for air under constant volume it is possible to obtain--by extrapolation to zero…

  19. Mosher Amides: Determining the Absolute Stereochemistry of Optically-Active Amines

    ERIC Educational Resources Information Center

    Allen, Damian A.; Tomaso, Anthony E., Jr.; Priest, Owen P.; Hindson, David F.; Hurlburt, Jamie L.

    2008-01-01

    The use of chiral reagents for the derivatization of optically-active amines and alcohols for the purpose of determining their enantiomeric purity or absolute configuration is a tool used by many chemists. Among the techniques used, Mosher's amide and Mosher's ester analyses are among the most reliable and one of the most often used. Despite this,…

  20. Measurement of absolute minority species concentration and temperature in a flame by the photothermal deflection spectroscopy technique.

    PubMed

    Li, Yunjing; Gupta, Rajendra

    2003-04-20

    It is experimentally demonstrated that absolute concentrations of minority species in flames can be measured by the photothermal deflection spectroscopy (PTDS) technique. In addition, the PTDS signal simultaneously yields the flame temperature the measurement point. Absolute concentration profiles of OH have been measured in a flat-flame burner with methane as fuel. The PTDS measurements agree well with those obtained independently by the absorption technique. The flame temperature measurements by PTDS are also in good agreement with those obtained by the Boltzmann distribution among the rotational levels of OH. PMID:12716166

  1. Metrological activity determination of 133Ba by sum-peak absolute method

    NASA Astrophysics Data System (ADS)

    da Silva, R. L.; de Almeida, M. C. M.; Delgado, J. U.; Poledna, R.; Santos, A.; de Veras, E. V.; Rangel, J.; Trindade, O. L.

    2016-07-01

    The National Laboratory for Metrology of Ionizing Radiation provides gamma sources of radionuclide and standardized in activity with reduced uncertainties. Relative methods require standards to determine the sample activity while the absolute methods, as sum-peak, not. The activity is obtained directly with good accuracy and low uncertainties. 133Ba is used in research laboratories and on calibration of detectors for analysis in different work areas. Classical absolute methods don't calibrate 133Ba due to its complex decay scheme. The sum-peak method using gamma spectrometry with germanium detector standardizes 133Ba samples. Uncertainties lower than 1% to activity results were obtained.

  2. Determination of absolute configuration using heavy atom based co-crystallization method: Halogen atom effects

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Rong; Fan, Xiaowu; Ding, Qiaoce; Mei, Xuefeng

    2016-09-01

    Heavy atom (chloride, bromide, and iodide) based co-crystals for determination of absolute configuration (AC) for chiral molecules were synthesized and evaluated. Co-crystals of cholestanol and L-ascorbic acid were analysed and the effects and potential benefits of varying the heavy atom are discussed. Changing the halogen atoms (chloride, bromide, or iodide) affects the co-crystal formation, X-ray absorption, and anomalous dispersion, and hence the ability to determine AC.

  3. Isolation and determination of absolute configurations of insect-produced methyl-branched hydrocarbons.

    PubMed

    Bello, Jan E; McElfresh, J Steven; Millar, Jocelyn G

    2015-01-27

    Although the effects of stereochemistry have been studied extensively for volatile insect pheromones, little is known about the effects of chirality in the nonvolatile methyl-branched hydrocarbons (MBCHs) used by many insects as contact pheromones. MBCHs generally contain one or more chiral centers and so two or more stereoisomeric forms are possible for each structure. However, it is not known whether insects biosynthesize these molecules in high stereoisomeric purity, nor is it known whether insects can distinguish the different stereoisomeric forms of MBCHs. This knowledge gap is due in part to the lack of methods for isolating individual MBCHs from the complex cuticular hydrocarbon (CHC) blends of insects, as well as the difficulty in determining the absolute configurations of the isolated MBCHs. To address these deficiencies, we report a straightforward method for the isolation of individual cuticular hydrocarbons from the complex CHC blend. The method was used to isolate 36 pure MBCHs from 20 species in nine insect orders. The absolute stereochemistries of the purified MBCHs then were determined by digital polarimetry. The absolute configurations of all of the isolated MBCHs were determined to be (R) by comparison with a library of synthesized, enantiomerically pure standards, suggesting that the biosynthetic pathways used to construct MBCHs are highly conserved within the Insecta. The development of a straightforward method for isolation of specific CHCs will enable determination of their functional roles by providing pure compounds for bioassays. PMID:25583471

  4. Isolation and determination of absolute configurations of insect-produced methyl-branched hydrocarbons

    PubMed Central

    Bello, Jan E.; McElfresh, J. Steven; Millar, Jocelyn G.

    2015-01-01

    Although the effects of stereochemistry have been studied extensively for volatile insect pheromones, little is known about the effects of chirality in the nonvolatile methyl-branched hydrocarbons (MBCHs) used by many insects as contact pheromones. MBCHs generally contain one or more chiral centers and so two or more stereoisomeric forms are possible for each structure. However, it is not known whether insects biosynthesize these molecules in high stereoisomeric purity, nor is it known whether insects can distinguish the different stereoisomeric forms of MBCHs. This knowledge gap is due in part to the lack of methods for isolating individual MBCHs from the complex cuticular hydrocarbon (CHC) blends of insects, as well as the difficulty in determining the absolute configurations of the isolated MBCHs. To address these deficiencies, we report a straightforward method for the isolation of individual cuticular hydrocarbons from the complex CHC blend. The method was used to isolate 36 pure MBCHs from 20 species in nine insect orders. The absolute stereochemistries of the purified MBCHs then were determined by digital polarimetry. The absolute configurations of all of the isolated MBCHs were determined to be (R) by comparison with a library of synthesized, enantiomerically pure standards, suggesting that the biosynthetic pathways used to construct MBCHs are highly conserved within the Insecta. The development of a straightforward method for isolation of specific CHCs will enable determination of their functional roles by providing pure compounds for bioassays. PMID:25583471

  5. Improved statistical determination of absolute neutrino masses via radiative emission of neutrino pairs from atoms

    NASA Astrophysics Data System (ADS)

    Zhang, Jue; Zhou, Shun

    2016-06-01

    The atomic transition from an excited state |e ⟩ to the ground state |g ⟩ by emitting a neutrino pair and a photon, i.e., |e ⟩→|g ⟩+|γ ⟩+|νi⟩+|ν¯j⟩ with i , j =1 , 2, 3, has been proposed by Yoshimura and his collaborators as an alternative way to determine the absolute scale m0 of neutrino masses. More recently, a statistical analysis of the fine structure of the photon spectrum from this atomic process has been performed [N. Song et al. Phys. Rev. D 93, 013020 (2016)] to quantitatively examine the experimental requirements for a realistic determination of absolute neutrino masses. In this paper, we show how to improve the statistical analysis and demonstrate that the previously required detection time can be reduced by one order of magnitude for the case of a 3 σ determination of m0˜0.01 eV with an accuracy better than 10%. Such an improvement is very encouraging for further investigations on measuring absolute neutrino masses through atomic processes.

  6. Electron cyclotron emission measurements on JET: Michelson interferometer, new absolute calibration, and determination of electron temperature.

    PubMed

    Schmuck, S; Fessey, J; Gerbaud, T; Alper, B; Beurskens, M N A; de la Luna, E; Sirinelli, A; Zerbini, M

    2012-12-01

    At the fusion experiment JET, a Michelson interferometer is used to measure the spectrum of the electron cyclotron emission in the spectral range 70-500 GHz. The interferometer is absolutely calibrated using the hot/cold technique and, in consequence, the spatial profile of the plasma electron temperature is determined from the measurements. The current state of the interferometer hardware, the calibration setup, and the analysis technique for calibration and plasma operation are described. A new, full-system, absolute calibration employing continuous data acquisition has been performed recently and the calibration method and results are presented. The noise level in the measurement is very low and as a result the electron cyclotron emission spectrum and thus the spatial profile of the electron temperature are determined to within ±5% and in the most relevant region to within ±2%. The new calibration shows that the absolute response of the system has decreased by about 15% compared to that measured previously and possible reasons for this change are presented. Temperature profiles measured with the Michelson interferometer are compared with profiles measured independently using Thomson scattering diagnostics, which have also been recently refurbished and recalibrated, and agreement within experimental uncertainties is obtained. PMID:23282107

  7. Determination of the absolute configuration of a chiral epoxide using foil induced Coulomb explosion imaging

    NASA Astrophysics Data System (ADS)

    Herwig, P.; Zawatzky, K.; Schwalm, D.; Grieser, M.; Heber, O.; Jordon-Thaden, B.; Krantz, C.; Novotný, O.; Repnow, R.; Schurig, V.; Vager, Z.; Wolf, A.; Trapp, O.; Kreckel, H.

    2015-09-01

    We have applied the method of foil-induced Coulomb Explosion Imaging (FCEI) to determine the handedness of a homochiral sample of the compound trans-2,3-dideuterooxirane C2OH2D2. We determined the compound to be of the (R, R)-econfiguration with a statistical significance of 5σ. As the molecular sample was chemically linked to the stereochemical reference standard glyceraldehyde, our assignment constitutes an independent verification of the absolute handedness of all compounds linked to this reference substance.

  8. Determination of the Absolute Configurations of Chiral Drugs Using Chiroptical Spectroscopy.

    PubMed

    Polavarapu, Prasad L

    2016-01-01

    Chiroptical spectroscopy has emerged as a promising tool for the determination of absolute configurations and predominant conformations of chiral molecules in academic laboratories. This promise has led to the adaption of chiroptical spectroscopic methods as valuable tools in chiral drug discovery research programs of the pharmaceutical industry. Most major pharmaceutical companies have invested in in-house chiroptical spectroscopy applications and reported successful outcomes. In the context of continuously increasing applications of chiroptical spectroscopy for chiral molecular structure determination, a review of recent developments and applications for chiral drugs is presented in this manuscript. PMID:27529201

  9. In situ TDLAS measurement of absolute acetylene concentration profiles in a non-premixed laminar counter-flow flame

    NASA Astrophysics Data System (ADS)

    Wagner, S.; Klein, M.; Kathrotia, T.; Riedel, U.; Kissel, T.; Dreizler, A.; Ebert, V.

    2012-06-01

    Acetylene (C2H2), as an important precursor for chemiluminescence species, is a key to understand, simulate and model the chemiluminescence and the related reaction paths. Hence we developed a high resolution spectrometer based on direct Tunable Diode Laser Absorption Spectroscopy (TDLAS) allowing the first quantitative, calibration-free and spatially resolved in situ C2H2 measurement in an atmospheric non-premixed counter-flow flame supported on a Tsuji burner. A fiber-coupled distributed feedback diode laser near 1535 nm was used to measure several absolute C2H2 concentration profiles (peak concentrations up to 9700 ppm) in a laminar non-premixed CH4/air flame ( T up to 1950 K) supported on a modified Tsuji counter-flow burner with N2 purge slots to minimize end flames. We achieve a fractional optical resolution of up to 5×10-5 OD (1 σ) in the flame, resulting in temperature-dependent acetylene detection limits for the P17e line at 6513 cm-1 of up to 2.1 ppmṡm. Absolute C2H2 concentration profiles were obtained by translating the burner through the laser beam using a DC motor with 100 μm step widths. Intercomparisons of the experimental C2H2 profiles with simulations using our new hydrocarbon oxidation mechanisms show excellent agreement in position, shape and in the absolute C2H2 values.

  10. Enantioselective Total Synthesis of (+)-Steenkrotin A and Determination of Its Absolute Configuration.

    PubMed

    Pan, Saiyong; Gao, Beiling; Hu, Jialei; Xuan, Jun; Xie, Hujun; Ding, Hanfeng

    2016-01-18

    The first enantioselective total synthesis of (+)-steenkrotin A has been achieved in 18 steps and 4.2 % overall yield. The key features of the strategy entail a Rh-catalyzed O-H bond insertion followed by an intramolecular carbonyl-ene reaction, two sequential SmI2 -mediated Ueno-Stork and ketyl-olefin cyclizations, and a cascade intramolecular aldol condensation/vinylogous retro-aldol/aldol process with inversion of the relative configuration at the C7 position. The absolute configuration of (+)-steenkrotin A was determined based on the stepwise construction of the stereocenters during the total synthesis. PMID:26660855

  11. Time dependent corrections to absolute gravity determinations in the establishment of modern gravity control

    NASA Astrophysics Data System (ADS)

    Dykowski, Przemyslaw; Krynski, Jan

    2015-04-01

    The establishment of modern gravity control with the use of exclusively absolute method of gravity determination has significant advantages as compared to the one established mostly with relative gravity measurements (e.g. accuracy, time efficiency). The newly modernized gravity control in Poland consists of 28 fundamental stations (laboratory) and 168 base stations (PBOG14 - located in the field). Gravity at the fundamental stations was surveyed with the FG5-230 gravimeter of the Warsaw University of Technology, and at the base stations - with the A10-020 gravimeter of the Institute of Geodesy and Cartography, Warsaw. This work concerns absolute gravity determinations at the base stations. Although free of common relative measurement errors (e.g. instrumental drift) and effects of network adjustment, absolute gravity determinations for the establishment of gravity control require advanced corrections due to time dependent factors, i.e. tidal and ocean loading corrections, atmospheric corrections and hydrological corrections that were not taken into account when establishing the previous gravity control in Poland. Currently available services and software allow to determine high accuracy and high temporal resolution corrections for atmospheric (based on digital weather models, e.g. ECMWF) and hydrological (based on hydrological models, e.g. GLDAS/Noah) gravitational and loading effects. These corrections are mostly used for processing observations with Superconducting Gravimeters in the Global Geodynamics Project. For the area of Poland the atmospheric correction based on weather models can differ from standard atmospheric correction by even ±2 µGal. The hydrological model shows the annual variability of ±8 µGal. In addition the standard tidal correction may differ from the one obtained from the local tidal model (based on tidal observations). Such difference at Borowa Gora Observatory reaches the level of ±1.5 µGal. Overall the sum of atmospheric and

  12. High-precision laser-assisted absolute determination of x-ray diffraction angles

    SciTech Connect

    Kubicek, K.; Braun, J.; Bruhns, H.; Crespo Lopez-Urrutia, J. R.; Mokler, P. H.; Ullrich, J.

    2012-01-15

    A novel technique for absolute wavelength determination in high-precision crystal x-ray spectroscopy recently introduced has been upgraded reaching unprecedented accuracies. The method combines visible laser beams with the Bond method, where Bragg angles ({theta} and -{theta}) are determined without any x-ray reference lines. Using flat crystals this technique makes absolute x-ray wavelength measurements feasible even at low x-ray fluxes. The upgraded spectrometer has been used in combination with first experiments on the 1s2p {sup 1}P{sub 1}{yields} 1s{sup 2} {sup 1}S{sub 0} w-line in He-like argon. By resolving a minute curvature of the x-ray lines the accuracy reaches there the best ever reported value of 1.5 ppm. The result is sensitive to predicted second-order QED contributions at the level of two-electron screening and two-photon radiative diagrams and will allow for the first time to benchmark predicted binding energies for He-like ions at this level of precision.

  13. Measurement of absolute concentrations of individual compounds in metabolite mixtures by gradient-selective time-zero 1H-13C HSQC with two concentration references and fast maximum likelihood reconstruction analysis.

    PubMed

    Hu, Kaifeng; Ellinger, James J; Chylla, Roger A; Markley, John L

    2011-12-15

    Time-zero 2D (13)C HSQC (HSQC(0)) spectroscopy offers advantages over traditional 2D NMR for quantitative analysis of solutions containing a mixture of compounds because the signal intensities are directly proportional to the concentrations of the constituents. The HSQC(0) spectrum is derived from a series of spectra collected with increasing repetition times within the basic HSQC block by extrapolating the repetition time to zero. Here we present an alternative approach to data collection, gradient-selective time-zero (1)H-(13)C HSQC(0) in combination with fast maximum likelihood reconstruction (FMLR) data analysis and the use of two concentration references for absolute concentration determination. Gradient-selective data acquisition results in cleaner spectra, and NMR data can be acquired in both constant-time and non-constant-time mode. Semiautomatic data analysis is supported by the FMLR approach, which is used to deconvolute the spectra and extract peak volumes. The peak volumes obtained from this analysis are converted to absolute concentrations by reference to the peak volumes of two internal reference compounds of known concentration: DSS (4,4-dimethyl-4-silapentane-1-sulfonic acid) at the low concentration limit (which also serves as chemical shift reference) and MES (2-(N-morpholino)ethanesulfonic acid) at the high concentration limit. The linear relationship between peak volumes and concentration is better defined with two references than with one, and the measured absolute concentrations of individual compounds in the mixture are more accurate. We compare results from semiautomated gsHSQC(0) with those obtained by the original manual phase-cycled HSQC(0) approach. The new approach is suitable for automatic metabolite profiling by simultaneous quantification of multiple metabolites in a complex mixture. PMID:22029275

  14. Absolute OH density determination by laser induced fluorescence spectroscopy in an atmospheric pressure RF plasma jet

    NASA Astrophysics Data System (ADS)

    Xiong, Q.; Nikiforov, A. Yu.; Li, L.; Vanraes, P.; Britun, N.; Snyders, R.; Lu, X. P.; Leys, C.

    2012-11-01

    In this paper, the ground state OH density is measured in high pressure plasma by laser-induced fluorescence (LIF) spectroscopy. The OH density determination is based on the simulation of the intensity fraction of fluorescence from the laser-excited level of OH (A) in the total detected LIF signal. The validity of this approach is verified in an atmospheric pressure Ar + H2O plasma jet sustained by a 13.56 MHz power supply. The transition line P1 (4) from OH (A, v' = 1, J' = 3) → OH (X, v'' = 0, J'' = 4) is used for the LIF excitation. The absolute OH density is determined to be 2.5 × 1019 m-3 at 1 mm away from the jet nozzle. It corresponds to a dissociation of 0.06% of the water vapor in the working gas. Different mechanisms of OH (X) production in the core of the plasma jet are discussed and analyzed.

  15. Rapid analytical determination of glutaraldehyde concentrations

    NASA Technical Reports Server (NTRS)

    Frigerio, N. A.; Shaw, M. H.

    1971-01-01

    Technique utilizes the iodimetric procedure which adds unknown excess of bisulfite to glutaraldehyde /GA/ then titrates unreacted bisulfite with standard iodine isotope to determine GA concentrations. Technique may interest microscopists, food researchers, biochemical or medical laboratories, and drug manufacturers.

  16. Determination of absolute configuration using ab initio calculation of optical rotation.

    PubMed

    Stephens, P J; Devlin, F J; Cheeseman, J R; Frisch, M J; Bortolini, O; Besse, P

    2003-01-01

    Ab initio Density Functional Theory (DFT) calculations of transparent spectral region, discrete frequency specific rotations were used to assign the absolute configurations (ACs) of: 1, 2H-naphtho[1,8-bc]thiophene 1-oxide; 2, m-F-phenyl glycidic acid methyl ester; 3, o-Br-phenyl glycidic acid methyl ester; 4, p-CH(3)-phenyl glycidic acid methyl ester; 5, 2-(1-hydroxyethyl)-chromen-4-one; and 6, 6-Br-2-(1-hydroxyethyl)-chromen-4-one. The ACs of 5 and 6 were previously determined via X-ray crystallography to be: 5, R(-)/S(+); 6, R(+)/S(-). The ACs obtained using [alpha](D) are the same for both 5 and 6: R(+)/S(-). We conclude that the previously reported AC of 5 is incorrect. PMID:12884375

  17. Determination of absolute interferometric phase using the beam-amplitude ratio technique

    SciTech Connect

    Bickel, D.L.; Hensley, W.H.

    1996-03-01

    Determination of the absolute phase difference (i.e., not modulo 2{pi}) is a key problem in interferometric synthetic aperture radar (IFSAR) for topographic mapping. One way of solving this problem requires use of a technique different from the basic interferometry to resolve a `coarse` angle measurement that lies within the IFSAR ambiguity angle. The method investigated in this paper involves taking advantage of the difference in the amplitude ratio versus elevation angle that occurs when the elevation beams of the two IFSAR antennas are pointed in slightly different directions. The performance of the technique is a function of the angular separation of the two beams, the elevation beamwidth, and the symmetry of the two beam-amplitude patterns. The performance required of the technique is set by the ambiguity angle of the interferometer. This paper presents an analysis of the beam-amplitude ratio technique and shows experimental results.

  18. Determination of RW3-to-water mass-energy absorption coefficient ratio for absolute dosimetry.

    PubMed

    Seet, Katrina Y T; Hanlon, Peta M; Charles, Paul H

    2011-12-01

    The measurement of absorbed dose to water in a solid-phantom may require a conversion factor because it may not be radiologically equivalent to water. One phantom developed for the use of dosimetry is a solid water, RW3 white-polystyrene material by IBA. This has a lower mass-energy absorption coefficient than water due to high bremsstrahlung yield, which affects the accuracy of absolute dosimetry measurements. In this paper, we demonstrate the calculation of mass-energy absorption coefficient ratios, relative to water, from measurements in plastic water and RW3 with an Elekta Synergy linear accelerator (6 and 10 MV photon beams) as well as Monte Carlo modeling in BEAMnrc and DOSXYZnrc. From this, the solid-phantom-to-water correction factor was determined for plastic water and RW3. PMID:21960410

  19. Fast GPU-based absolute intensity determination for energy-dispersive X-ray Laue diffraction

    NASA Astrophysics Data System (ADS)

    Alghabi, F.; Send, S.; Schipper, U.; Abboud, A.; Pietsch, U.; Kolb, A.

    2016-01-01

    This paper presents a novel method for fast determination of absolute intensities in the sites of Laue spots generated by a tetragonal hen egg-white lysozyme crystal after exposure to white synchrotron radiation during an energy-dispersive X-ray Laue diffraction experiment. The Laue spots are taken by means of an energy-dispersive X-ray 2D pnCCD detector. Current pnCCD detectors have a spatial resolution of 384 × 384 pixels of size 75 × 75 μm2 each and operate at a maximum of 400 Hz. Future devices are going to have higher spatial resolution and frame rates. The proposed method runs on a computer equipped with multiple Graphics Processing Units (GPUs) which provide fast and parallel processing capabilities. Accordingly, our GPU-based algorithm exploits these capabilities to further analyse the Laue spots of the sample. The main contribution of the paper is therefore an alternative algorithm for determining absolute intensities of Laue spots which are themselves computed from a sequence of pnCCD frames. Moreover, a new method for integrating spectral peak intensities and improved background correction, a different way of calculating mean count rate of the background signal and also a new method for n-dimensional Poisson fitting are presented.We present a comparison of the quality of results from the GPU-based algorithm with the quality of results from a prior (base) algorithm running on CPU. This comparison shows that our algorithm is able to produce results with at least the same quality as the base algorithm. Furthermore, the GPU-based algorithm is able to speed up one of the most time-consuming parts of the base algorithm, which is n-dimensional Poisson fitting, by a factor of more than 3. Also, the entire procedure of extracting Laue spots' positions, energies and absolute intensities from a raw dataset of pnCCD frames is accelerated by a factor of more than 3.

  20. Using star tracks to determine the absolute pointing of the Fluorescence Detector telescopes of the Pierre Auger Observatory

    SciTech Connect

    De Donato, Cinzia; Sanchez, Federico; Santander, Marcos; Natl.Tech.U., San Rafael; Camin, Daniel; Garcia, Beatriz; Grassi, Valerio; /Milan U. /INFN, Milan

    2005-05-01

    To accurately reconstruct a shower axis from the Fluorescence Detector data it is essential to establish with high precision the absolute pointing of the telescopes. To d that they calculate the absolute pointing of a telescope using sky background data acquired during regular data taking periods. The method is based on the knowledge of bright star's coordinates that provide a reliable and stable coordinate system. it can be used to check the absolute telescope's pointing and its long-term stability during the whole life of the project, estimated in 20 years. They have analyzed background data taken from January to October 2004 to determine the absolute pointing of the 12 telescopes installed both in Los Leones and Coihueco. The method is based on the determination of the mean-time of the variance signal left by a star traversing a PMT's photocathode which is compared with the mean-time obtained by simulating the track of that star on the same pixel.

  1. Non-destructive method for determining neutron exposure and constituent concentrations of a body

    DOEpatents

    Gold, Raymond; McElroy, William N.

    1986-01-01

    A non-destructive method for determination of neutron exposure and constituent concentrations in an object, such as reactor pressure vessel, is based on the observation of characteristic gamma-rays emitted by activation products in the object by using a unique continuous gamma-ray spectrometer. The spectrometer views the object through appropriate collimators to determine the absolute emission rate of these characteristic gamma-rays, thereby ascertaining the absolute activity of given activation products in the object. These data can then be used to deduce the spatial and angular dependence of neutron exposure or the spatial constituent concentration at regions of interest within the object.

  2. Absolute determination of the gelling point of gelatin under quasi-thermodynamic equilibrium.

    PubMed

    Bellini, Franco; Alberini, Ivana; Ferreyra, María G; Rintoul, Ignacio

    2015-05-01

    Thermodynamic studies on phase transformation of biopolymers in solution are useful to understand their nature and to evaluate their technological potentials. Thermodynamic studies should be conducted avoiding time-related phenomena. This condition is not easily achieved in hydrophilic biopolymers. In this contribution, the simultaneous effects of pH, salt concentration, and cooling rate (Cr) on the folding from random coil to triple helical collagen-like structures of gelatin were systematically studied. The phase transformation temperature at the absolute invariant condition of Cr = 0 °C/min (T(T)Cr=0) ) is introduced as a conceptual parameter to study phase transformations in biopolymers under quasi-thermodynamic equilibrium and avoiding interferences coming from time-related phenomena. Experimental phase diagrams obtained at different Cr are presented. The T(T)(Cr=0) compared with pH and TT(Cr=0) compared with [NaCl] diagram allowed to explore the transformation process at Cr = 0 °C/min. The results were explained by electrostatic interactions between the biopolymers and its solvation milieu. PMID:25832543

  3. Systematic determination of absolute absorption cross-section of individual carbon nanotubes

    PubMed Central

    Liu, Kaihui; Hong, Xiaoping; Choi, Sangkook; Jin, Chenhao; Capaz, Rodrigo B.; Kim, Jihoon; Wang, Wenlong; Bai, Xuedong; Louie, Steven G.; Wang, Enge; Wang, Feng

    2014-01-01

    Optical absorption is the most fundamental optical property characterizing light–matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important

  4. Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels

    PubMed Central

    Khokhlova, Vera A.; Shmeleva, Svetlana M.; Gavrilov, Leonid R.; Martin, Eleanor; Sadhoo, Neelaksh; Shaw, Adam

    2013-01-01

    Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm2 to at least 50 W/cm2. Significantly higher intensities could be measured simply by reducing the duty cycle. PMID:23927199

  5. Infrared mapping of ultrasound fields generated by medical transducers: feasibility of determining absolute intensity levels.

    PubMed

    Khokhlova, Vera A; Shmeleva, Svetlana M; Gavrilov, Leonid R; Martin, Eleanor; Sadhoo, Neelaksh; Shaw, Adam

    2013-08-01

    Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2 mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1 MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm(2) to at least 50 W/cm(2). Significantly higher intensities could be measured simply by reducing the duty cycle. PMID:23927199

  6. An absolute instrument for determination of the speed of sound in water.

    PubMed

    Li, Zhiwei; Zhu, Junchao; Li, Tao; Zhang, Baofeng

    2016-05-01

    An apparatus for the absolute determination of the sound speed in water based on the time-of-flight technique is described. The time measurement is realized by hardware circuits and the distance measurement by a double-beam plane-mirror interferometer. A highly accurate time chip, with a resolution of approximately 90 ps, is employed for time measurements. The acoustic path length is adjustable and can be measured directly. Two transducers are used for transmitting and receiving ultrasonic signals without reflection. The transducers are immersed in a thermostatic vessel that maintains bath temperature with high stability. The speed of sound in pure water was measured at ambient pressure and at the temperatures 308 K, 303 K, 298 K, and 293 K. The achieved measurement uncertainties are 2 mK for temperature and 0.045 m/s for speed of sound. The results are compared to data from the literature, equation of state models, and measurements by two commercial sensors in the same experiment, showing excellent agreement among them. PMID:27250470

  7. A general method for the calculation of absolute trace gas concentrations in air and breath from selected ion flow tube mass spectrometry data

    NASA Astrophysics Data System (ADS)

    Spanel, Patrik; Dryahina, Kseniya; Smith, David

    2006-03-01

    A complete description is presented of a numerical method that allows the calculation, in real time, of absolute concentrations of trace gases, including volatile organic compounds and water vapour, from selected ion flow tube mass spectrometry, SIFT-MS, data. No assumptions are made concerning the SIFT-MS instrument size or its configuration and thus the calculation can be applied to the currently available, relatively large instruments and the anticipated new generation of smaller SIFT-MS instruments. This numerical method clearly distinguishes those parameters that are obviously specific to a particular instrument, including flow tube geometry, degree of mass discrimination in the analytical mass spectrometer and flow tube reaction time, from general fundamental processes, in particular the differential diffusive loss of ions along the flow tube that is dependent on the properties of those ions involved in the determination of the concentrations of particular trace gases. The essential reaction and transport kinetics are outlined, which describe the formation and loss of the product ions formed in the chemical ionisation of the trace gases by the precursor ions. A generalised calculation of the required ionic diffusion coefficients is introduced with options either for their accurate determination from the molecular geometry of ions or for less accurate but simpler estimates obtained using just the ionic mass. Based on the above ideas, a straightforward calculation sequence is shown to determine trace gas concentrations by SIFT-MS, and its utility demonstrated by an example of the analysis of acetone in exhaled breath.

  8. Asymmetric total synthesis of (-)-lundurine B and determination of its absolute stereochemistry.

    PubMed

    Nakajima, Masaya; Arai, Shigeru; Nishida, Atsushi

    2015-04-01

    A total synthesis of the Kopsia tenuis alkaloid (-)-lundurine B has been achieved. A quaternary chiral carbon has been created by an asymmetric deprotonation using a symmetric spiro cyclohexanone intermediate with a chiral lithium amide. The hexacyclic skeleton was sequentially constructed through metal-mediated reactions. The absolute stereochemistry of intermediate 5 has been unambiguously established by X-ray crystallographic analysis. This is the first description of the absolute stereochemistry of Kopsia tenuis alkaloids based on chemical synthesis. PMID:25601233

  9. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  10. Absolute masses and radii determination in multiplanetary systems without stellar models

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Díaz, R. F.; Mardling, R.; Barros, S. C. C.; Damiani, C.; Bruno, G.; Bonfils, X.; Deleuil, M.

    2015-11-01

    The masses and radii of extrasolar planets are key observables for understanding their interior, formation and evolution. While transit photometry and Doppler spectroscopy are used to measure the radii and masses respectively of planets relative to those of their host star, estimates for the true values of these quantities rely on theoretical models of the host star which are known to suffer from systematic differences with observations. When a system is composed of more than two bodies, extra information is contained in the transit photometry and radial velocity data. Velocity information (finite speed-of-light, Doppler) is needed to break the Newtonian MR-3 degeneracy. We performed a photodynamical modelling of the two-planet transiting system Kepler-117 using all photometric and spectroscopic data available. We demonstrate how absolute masses and radii of single-star planetary systems can be obtained without resorting to stellar models. Limited by the precision of available radial velocities (38 m s-1), we achieve accuracies of 20 per cent in the radii and 70 per cent in the masses, while simulated 1 m s-1 precision radial velocities lower these to 1 per cent for the radii and 2 per cent for the masses. Since transiting multiplanet systems are common, this technique can be used to measure precisely the mass and radius of a large sample of stars and planets. We anticipate these measurements will become common when the TESS and PLATO mission provide high-precision light curves of a large sample of bright stars. These determinations will improve our knowledge about stars and planets, and provide strong constraints on theoretical models.

  11. A new determination of the Geneva photometric passbands and their absolute calibration

    NASA Astrophysics Data System (ADS)

    Rufener, F.; Nicolet, B.

    The consensus regarding the absolute calibrations of the spectra of alpha Lyr and subdwarfs provoked a revision of the calibration of the Geneva photometric system passbands. The alterations made to the earlier version by Rufener and Maeder (1971) are smaller than plus or minus -5 percent. The new response functions are presented in tabular form for an equiphotonic flux. An absolute spectrophotometric adjustment allows to obtain for each entry of the Geneva catalog (28,000 stars) a corresponding spectrophotometric description in SI units. The definition and the means of computing the necessary quasi-isophotal frequencies or wavelengths are given. The coherence of the Geneva catalog with several sets of absolute spectrophotometric data is examined. A correction for the entire Gunn and Stryker (1983) catalog is proposed.

  12. Determination of the Absolute Configuration of the Pseudo-Symmetric Natural Product Elatenyne by the Crystalline Sponge Method.

    PubMed

    Urban, Sylvia; Brkljača, Robert; Hoshino, Manabu; Lee, Shoukou; Fujita, Makoto

    2016-02-01

    Elatenyne is a marine natural product that was isolated in 1986. Despite its simple 2,2'-bifuranyl backbone, its relative structure was only recently determined. The absolute configuration of elatenyne has still not been unequivocally confirmed because of its pseudo-meso core structure, which results in a specific rotation, [α]D  , of almost zero. In this work, the structure of natural elatenyne was determined by the crystalline sponge method and the use of a porous coordination network (a crystalline sponge) capable of absorbing organic guests; in the sponge, the absorbed guests are ordered and crystallographically observable. The crystalline sponge could differentiate between the two very similar alkyl side chains, and the absolute structure of elatenyne was thus reliably determined. The total amount required for the experiments was only approximately 100 μg, and the majority (95 μg) could be recovered after the experiments. PMID:26880368

  13. Determination of the absolute isotopic composition and Atomic Weight of a reference sample of natural iron

    NASA Astrophysics Data System (ADS)

    Taylor, P. D. P.; Maeck, R.; de Bièvre, P.

    1992-11-01

    Absolute values have been obtained by means of thermal ionisation mass spectrometry for the iron isotope abundance ratios of a sample of metallic iron of natural isotopic composition. This was achieved by calibrating the mass spectrometric measurement procedure using five different synthetic isotope mixtures, prepared from carefully characterised enriched isotope carrier compounds, viz. 54Fe2O3 and 56Fe2O3. These mixtures were made up at three different n(54Fe)/n(56Fe) ratios, covering a ratio range of more than two orders of magnitude, in order to determine the extent of the isotope fractionation in the ion source. Two mixtures bracket the natural ratio, two mixtures have ratio values approximating to unity, and one mixture has a ratio of about 10. The total relative uncertainty on the ratio values of the mixtures varies between 2 and 7 × 10-4 (2s). Three different mass spectrometric measurement procedures were developed, all using a silica-gel/boric acid ionisation enhancer. Measurements were carried out on two different instruments. The n(54Fe)/n(56Fe) ratio of the synthetic mixtures and of the natural iron isotopic reference material (IRM) were measured using a mass spectrometer with Faraday detector. Both the n(57Fe)/n(56Fe) and n(58Fe)/n(56Fe) ratios of the natural iron IRM were determined using the same instrument but operated at a higher ionisation temperature (1430°C instead of 1350°C) and using an internal normalisation procedure. For the determination of the abundances of the minor isotopes in the enriched isotope carrier compounds, an instrument equipped with a calibrated ion counting device was used and the ionisation temperature was 1150°C. Using the latter instrument and method, the n(54Fe)/n(56Fe) ratio of the IRM was found to a gree within 4 × 10-5 with the calibrated value of the Faraday measurements, indicating that experimental conditions were well controlled in both cases. Compared to the current IUPAC data (Atomic Weights of the Elements

  14. Determining Concentration of Nanoparticles from Ellipsometry

    NASA Technical Reports Server (NTRS)

    Venkatasubbarao, Srivatsa; Kempen, Lothar U.; Chipman, Russell

    2008-01-01

    various concentrations of gold nanoparticles having an assumed radius. The modeled data indicates distinct spectral features for both the real and the imaginary part of the dielectric function. An ellipsometric measurement would determine this distinct feature and thus can be used to measure nanoparticle concentration. By "ellipsometric responses" is meant the intensities of light measured in various polarization states as functions of the angle of incidence and the polarization states of the incident light. These calculated ellipsometric responses are used as calibration curves: Data from subsequent ellipsometric measurements on real specimens are compared with the calibration curves. The concentration of the nanoparticles on a specimen is assumed to be that of the calibration curve that most closely matches the data pertaining to that specimen.

  15. Novel determinants of the neuronal Cl(-) concentration.

    PubMed

    Delpire, Eric; Staley, Kevin J

    2014-10-01

    It is now a well-accepted view that cation-driven Cl(-) transporters in neurons are involved in determining the intracellular Cl(-) concentration. In the present review, we propose that additional factors, which are often overlooked, contribute substantially to the Cl(-) gradient across neuronal membranes. After briefly discussing the data supporting and opposing the role of cation-chloride cotransporters in regulating Cl(-), we examine the participation of the following factors in the formation of the transmembrane Cl(-) gradient: (i) fixed 'Donnan' charges inside and outside the cell; (ii) the properties of water (free vs. bound); and (iii) water transport through the cotransporters. We demonstrate a steep relationship between intracellular Cl(-) and the concentration of fixed negative charges on macromolecules. We show that in the absence of water transport through the K(+)-Cl(-) cotransporter, a large osmotic gradient builds at concentrations below or above a set value of 'Donnan' charges, and show that at any value of these fixed charges, the reversal potential for Cl(-) equates that of K(+). When the movement of water across the membrane is a source of free energy, it is sufficient to modify the movement of Cl(-) through the cotransporter. In this scenario, the reversal potential for Cl(-) does not closely follow that of K(+). Furthermore, our simulations demonstrate that small differences in the availability of freely diffusible water between inside and outside the cell greatly affect the Cl(-) reversal potential, particularly when osmolar transmembrane gradients are minimized, for example by idiogenic osmoles. We also establish that the presence of extracellular charges has little effect on the chloride reversal potential, but greatly affects the effective inhibitory conductance for Cl(-). In conclusion, our theoretical analysis of the presence of fixed anionic charges and water bound on macromolecules inside and outside the cell greatly impacts both Cl

  16. Novel determinants of the neuronal Cl− concentration

    PubMed Central

    Delpire, Eric; Staley, Kevin J

    2014-01-01

    It is now a well-accepted view that cation-driven Cl− transporters in neurons are involved in determining the intracellular Cl− concentration. In the present review, we propose that additional factors, which are often overlooked, contribute substantially to the Cl− gradient across neuronal membranes. After briefly discussing the data supporting and opposing the role of cation–chloride cotransporters in regulating Cl−, we examine the participation of the following factors in the formation of the transmembrane Cl− gradient: (i) fixed ‘Donnan’ charges inside and outside the cell; (ii) the properties of water (free vs. bound); and (iii) water transport through the cotransporters. We demonstrate a steep relationship between intracellular Cl− and the concentration of fixed negative charges on macromolecules. We show that in the absence of water transport through the K+–Cl− cotransporter, a large osmotic gradient builds at concentrations below or above a set value of ‘Donnan’ charges, and show that at any value of these fixed charges, the reversal potential for Cl− equates that of K+. When the movement of water across the membrane is a source of free energy, it is sufficient to modify the movement of Cl− through the cotransporter. In this scenario, the reversal potential for Cl− does not closely follow that of K+. Furthermore, our simulations demonstrate that small differences in the availability of freely diffusible water between inside and outside the cell greatly affect the Cl− reversal potential, particularly when osmolar transmembrane gradients are minimized, for example by idiogenic osmoles. We also establish that the presence of extracellular charges has little effect on the chloride reversal potential, but greatly affects the effective inhibitory conductance for Cl−. In conclusion, our theoretical analysis of the presence of fixed anionic charges and water bound on macromolecules inside and outside the cell greatly impacts both

  17. Determination of the absolute configuration of mono-saccharides in complex carbohydrates by capillary G.L.C.

    PubMed

    Gerwig, G J; Kamerling, J P; Vliegenthart, J F

    1979-12-01

    The absolute configuration of neutral monosaccharides, 2-acetamido-2-deoxy sugars, and uronic acids can be determined by capillary g.l.c. on SE-30 after glycosidation with (-)-2-butanol and protection of the remaining polar groups. The method is illustrated by application to mixtures of the constituent sugars of the capsular polysaccharide from Klebsiella type 57, alpha 1-acid glycoprotein, mucus glycoproteins, and the methylated, acidic polysaccharide from the coccoliths of Emiliania huxleyi (Lohmann) Kamptner. PMID:519653

  18. Absolute measurement of cerebral optical coefficients, hemoglobin concentration and oxygen saturation in old and young adults with near-infrared spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We present near-infrared spectroscopy measurement of absolute cerebral hemoglobin concentration and saturation in a large sample of 36 healthy elderly (mean age, 85 ± 6 years) and 19 young adults (mean age, 28 ± 4 years). Non-invasive measurements were obtained on the forehead using a commercially a...

  19. Determination of the Absolute Number of Cytokine mRNA Molecules within Individual Activated Human T Cells

    NASA Technical Reports Server (NTRS)

    Karr, Laurel J.; Marshall, Gwen; Hockett, Richard D.; Bucy, R. Pat; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A primary function of activated T cells is the expression and subsequent secretion of cytokines, which orchestrate the differentiation of other lymphocytes, modulate antigen presenting cell activity, and alter vascular endothelium to mediate an immune response. Since many features of immune regulation probably result from modest alterations of endogenous rates of multiple interacting processes, quantitative analysis of the frequency and specific activity of individual T cells is critically important. Using a coordinated set of quantitative methods, the absolute number of molecules of several key cytokine mRNA species in individual T cells has been determined. The frequency of human blood T cells activated in vitro by mitogens and recall protein antigens was determined by intracellular cytokine protein staining, in situ hybridization for cytokine mRNA, and by limiting dilution analysis for cytokine mRNA+ cells. The absolute number of mRNA molecules was simultaneously determined in both homogenates of the entire population of cells and in individual cells obtained by limiting dilution, using a quantitative, competitive RT-PCR assay. The absolute numbers of mRNA molecules in a population of cells divided by the frequency of individual positive cells, yielded essentially the same number of mRNA molecules per cell as direct analysis of individual cells by limiting dilution analysis. Mean numbers of mRNA per positive cell from both mitogen and antigen activated T cells, using these stimulation conditions, were 6000 for IL-2, 6300 for IFN-gamma, and 1600 for IL-4.

  20. Studies Culminating in the Total Synthesis and Determination of the Absolute Configuration of (-)-Saudin

    PubMed Central

    Boeckman, Robert K.; del Rosario Ferreira, Maria Rico; Mitchell, Lorna H.; Shao, Pengcheng; Neeb, Michael J.; Fang, Yue

    2011-01-01

    A full account of studies that culminated in the total synthesis of both antipodes and the assignment of its absolute configuration of Saudin, a hypoglycemic natural product. Two approaches are described, the first proceeding though bicyclic lactone intermediates and related second monocyclic esters. The former was obtained via asymmetric Diels-Alder cycloaddition and the latter by an asymmetric annulation protocol. Both approaches employ a Lewis acid promoted Claisen rearrangement, with the successful approach taking advantage of bidentate chelation to control the facial selectivity of the key Claisen rearrangement PMID:22523435

  1. Monte Carlo calculations for absolute dosimetry to determine machine outputs for proton therapy fields

    PubMed Central

    Paganetti, Harald

    2008-01-01

    The prescribed dose in radiation therapy has to be converted into machine monitor units for patient treatment. This is done routinely for each spread-out Bragg peak (SOBP) field either by calibration measurements, by using analytical algorithms or by relying on empirical data. At the Northeast Proton Therapy Center, a monitor unit corresponds to a fixed amount of charge collected in a segmented transmission ionization chamber inside the treatment head. The goal of this work was to use a detailed Monte Carlo model of the treatment head to calculate the dose delivered to the patient as a function of ionization chamber reading, i.e. to yield absolute dose in patients in terms of machine monitor units. The results show excellent agreement with measurements. For 50 SOBP fields considered in this study, the mean absolute difference between the experimental and the calculated value is 1.5%, where ~50% of the fields agree within 1%. This is within the uncertainties of the data. The Monte Carlo method has advantages over analytical algorithms because it takes into account scattered and secondary radiation, does not rely on empirical parameters, and provides a tool to study the influence of parts of the treatment head on the ionization chamber reading. Compared to experimental methods the Monte Carlo method has the advantage of being able to verify the dose in the patient geometry. PMID:16723767

  2. The realization of the dipole (γ, γ) method and its application to determine the absolute optical oscillator strengths of helium

    PubMed Central

    Xu, Long-Quan; Liu, Ya-Wei; Kang, Xu; Ni, Dong-Dong; Yang, Ke; Hiraoka, Nozomu; Tsuei, Ku-Ding; Zhu, Lin-Fan

    2015-01-01

    The dipole (γ, γ) method, which is the inelastic x-ray scattering operated at a negligibly small momentum transfer, is proposed and realized to determine the absolute optical oscillator strengths of the vanlence-shell excitations of atoms and molecules. Compared with the conventionally used photoabsorption method, this new method is free from the line saturation effect, which can seriously limit the accuracies of the measured photoabsorption cross sections for discrete transitions with narrow natural linewidths. Furthermore, the Bethe-Born conversion factor of the dipole (γ, γ) method varies much more slowly with the excitation energy than does that of the dipole (e, e) method. Absolute optical oscillator strengths for the excitations of 1s2 → 1 snp(n = 3 − 7) of atomic helium have been determined using the high-resolution dipole (γ, γ) method, and the excellent agreement of the present measurements with both those measured by the dipole (e, e) method and the previous theoretical calculations indicates that the dipole (γ, γ) method is a powerful tool to measure the absolute optical oscillator strengths of the valence-shell excitations of atoms and molecules. PMID:26678298

  3. Determination of natural in vivo noble-gas concentrations in human blood.

    PubMed

    Tomonaga, Yama; Brennwald, Matthias S; Livingstone, David M; Tomonaga, Geneviève; Kipfer, Rolf

    2014-01-01

    Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry. PMID:24811123

  4. Determination of Natural In Vivo Noble-Gas Concentrations in Human Blood

    PubMed Central

    Tomonaga, Yama; Brennwald, Matthias S.; Livingstone, David M.; Tomonaga, Geneviève; Kipfer, Rolf

    2014-01-01

    Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry. PMID:24811123

  5. Absolute site effects in Kachchh, India, determined from aftershocks of the 2002 Bhuj earthquake.

    NASA Astrophysics Data System (ADS)

    Malagnini, L.; Mayeda, K.; Bodin, P.; Akinci, A.

    2004-12-01

    What can be learned about absolute site effects on ground motions from recordings of aftershocks at ten temporary seismic stations, none of which could be considered a "reference" (hard rock) site, and for which no geotechnical information is available? This challenge motivated our current study of Bhuj aftershocks; and our answer, briefly put, is: quite a bit. We started by constraining the regional attenuation and geometric spreading: this was the result of an earlier study [Bodin et al., BSSA 2004], the goal of which was to be able to reproduce the general character of the observations with a constrained set of stochastic synthetic ground motions. Our present work is based on the same aftershock data we used in the prior study. We first produced stable and reliable, unbiased source moment-rate spectra using the technique described by Mayeda et al., [BSSA, 2003]. With these known "absolute" source spectra, and the propagation terms we quantified in the previous study we inverted for the site response using only the largest ~200 earthquakes (M>2.8) in each of two depth ranges (0-25 km, and 20-40 km), to yield the "absolute" site terms for horizontal and vertical ground motions. We were able to obtain stable results in the 1-14 hz frequency band. The results reveal that the site terms generally share a common character: small amplifications (near unity) at the longer-period end of the pass-band, and decreases (perhaps due to attenuation or near-site scattering) at the higher frequency end. This character is evident in a similar study of earthquake ground motions in the Alps at sites on hard rock [Malagnini et al., BSSA 2004]. In contrast to Alpine hard rock sites, however, the vertical site terms at our sediment and soft-rock sites are generally rather flat and featureless. We observe differences in site response between stations which appeared to be on similar geologic conditions, and vice versa. For sites that appear to be on deep unconsolidated soils

  6. 30 CFR 33.32 - Determination of dust concentration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Determination of dust concentration. 33.32... MINES Test Requirements § 33.32 Determination of dust concentration. (a) Concentrations of airborne dust... microscopic technique shall be employed in determining concentrations of dust in terms of millions...

  7. 30 CFR 33.32 - Determination of dust concentration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Determination of dust concentration. 33.32... MINES Test Requirements § 33.32 Determination of dust concentration. (a) Concentrations of airborne dust... microscopic technique shall be employed in determining concentrations of dust in terms of millions...

  8. 30 CFR 33.32 - Determination of dust concentration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Determination of dust concentration. 33.32... MINES Test Requirements § 33.32 Determination of dust concentration. (a) Concentrations of airborne dust... microscopic technique shall be employed in determining concentrations of dust in terms of millions...

  9. 30 CFR 33.32 - Determination of dust concentration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Determination of dust concentration. 33.32... MINES Test Requirements § 33.32 Determination of dust concentration. (a) Concentrations of airborne dust... microscopic technique shall be employed in determining concentrations of dust in terms of millions...

  10. 30 CFR 33.32 - Determination of dust concentration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Determination of dust concentration. 33.32... MINES Test Requirements § 33.32 Determination of dust concentration. (a) Concentrations of airborne dust... microscopic technique shall be employed in determining concentrations of dust in terms of millions...

  11. Absolute concentration of free volume-type defects in ultrafine-grained Fe prepared by high-pressure torsion

    PubMed Central

    Oberdorfer, Bernd; Lorenzoni, Bernd; Unger, Katrin; Sprengel, Wolfgang; Zehetbauer, Michael; Pippan, Reinhard; Würschum, Roland

    2010-01-01

    A maximum excess volume ΔV/V ≈ 1.9 × 10−3 in ultrafine-grained Fe prepared by high-pressure torsion is determined by measurements of the irreversible length change upon annealing employing a high-resolution differential dilatometer. Since dislocations and equilibrium-type grain boundaries cannot fully account for the observed released excess volume, the present study yields evidence for a high concentration of free volume-type defects inherent to nanophase materials, which is considered to be the main source of their particular properties, such as strongly enhanced diffusivities. PMID:21785571

  12. Determination of carrier concentration and compensation microprofiles in GaAs

    NASA Technical Reports Server (NTRS)

    Jastrzebski, L.; Lagowski, J.; Walukiewicz, W.; Gatos, H. C.

    1980-01-01

    Simultaneous microprofiling of semiconductor free carrier, donor, and acceptor concentrations was achieved for the first time from the absolute value of the free carrier absorption coefficient and its wavelength dependence determined by IR absorption in a scanning mode. Employing Ge- and Si-doped melt-grown GaAs, striking differences were found between the variations of electron concentration and those of ionized impurity concentrations. These results showed clearly that the electronic characteristics of this material are controlled by amphoteric doping and deviations from stoichiometry rather than by impurity segregation.

  13. Pyridine Hemochromagen Assay for Determining the Concentration of Heme in Purified Protein Solutions

    PubMed Central

    Barr, Ian; Guo, Feng

    2016-01-01

    Heme is a common cofactor in proteins, found in hemoglobin, myoglobin, cytochrome P450, DGCR8, and nitric oxide synthase, among others. This protocol describes a method for quantifying heme that works best in purified protein samples. This protocol might be used to, for example, determine whether a given heme-binding protein is fully occupied by heme, thus allowing correlation of heme content with activity. This requires the absolute heme concentration and an accurate protein concentration. Another use is to determine the extinction coefficients of a heme-bound protein. This assay is fast, easy, and reproducible if done correctly. PMID:27390766

  14. Absolute polarity determination of teeth cementum by phase sensitive second harmonic generation microscopy.

    PubMed

    Aboulfadl, Hanane; Hulliger, Jürg

    2015-10-01

    The absolute sign of local polarity in relation to the biological growth direction has been investigated for teeth cementum using phase sensitive second harmonic generation microscopy (PS-SHGM) and a crystal of 2-cyclooctylamino-5-nitropyridine (COANP) as a nonlinear optic (NLO) reference material. A second harmonic generation (SHG) response was found in two directions of cementum: radial (acellular extrinsic fibers that are oriented more or less perpendicular to the root surface) and circumferential (cellular intrinsic fibers that are oriented more or less parallel to the surface). A mono-polar state was demonstrated for acellular extrinsic cementum. However, along the different parts of cementum in circumferential direction, two corresponding domains were observed featuring an opposite sign of polarity indicative for a bi-polar microscopic state of cellular intrinsic cementum. The phase information showed that the orientation of radial collagen fibrils of cementum is regularly organized with the donor (D) groups pointing to the surface. Circumferential collagen molecules feature orientational disorder and are oriented up and down in random manner showing acceptor or donor groups at the surface of cementum. Considering that the cementum continues to grow in thickness throughout life, we can conclude that the cementum is growing circumferentially in two opposite directions and radially in one direction. A Markov chain type model for polarity formation in the direction of growth predicts D-groups preferably appearing at the fiber front. PMID:26297858

  15. Unambiguous Determination of the Absolute Configuration of Dimeric Stilbene Glucosides from the Rhizomes of Gnetum africanum.

    PubMed

    Buffeteau, Thierry; Cavagnat, Dominique; Bisson, Jonathan; Marchal, Axel; Kapche, Gilbert D; Battistini, Ilaria; Da Costa, Gregory; Badoc, Alain; Monti, Jean-Pierre; Mérillon, Jean-Michel; Waffo-Téguo, Pierre

    2014-08-22

    Dimeric stilbene glucosides 1-3 [two diastereomers of (-)-gnemonoside A (1a and 1b), (-)-gnemonoside C (2), and (-)-gnemonoside D (3)] as well as a mixture of the two enantiomers of gnetin C (4) were isolated from the rhizomes of Gnetum africanum. The two enantiomers of gnetin C, (+)-4 and (-)-4, were obtained from the aglycones of 1a and 1b, respectively. The configurations of these stilbenoids were investigated by NMR and vibrational circular dichroism (VCD) experiments. The absolute configurations of (-)-1a, (-)-2, (-)-3, and (-)-4 were established as 7aS,8aS by VCD spectroscopy in combination with density functional theory calculations. The antiamyloidogenic activity of the isolated stilbenes was also evaluated versus beta-amyloid fibrils. The four glucosides of gnetin C (1a, 1b, 2, and 3) were found to be the most active compounds, with inhibition percentages of 56, 56, 58, and 54 at 10 μM, respectively. PMID:25093453

  16. An absolute method for determination of misalignment of an immersion ultrasonic transducer.

    PubMed

    Narayanan, M M; Singh, Narender; Kumar, Anish; Babu Rao, C; Jayakumar, T

    2014-12-01

    An absolute methodology has been developed for quantification of misalignment of an ultrasonic transducer using a corner-cube retroreflector. The amplitude based and the time of flight (TOF) based C-scans of the reflector are obtained for various misalignments of the transducer. At zero degree orientation of the transducer, the vertical positions of the maximum amplitude and the minimum TOF in the C-scan coincide. At any other orientation of the transducer with the horizontal plane, there is a vertical shift in the position of the maximum amplitude with respect to the minimum TOF. The position of the minimum (TOF) remains the same irrespective of the orientation of the transducer and hence is used as a reference for any misalignment of the transducer. With the measurement of the vertical shift and the horizontal distance between the transducer and the vertex of the reflector, the misalignment of the transducer is quantified. Based on the methodology developed in the present study, retroreflectors are placed in the Indian 500MWe Prototype Fast Breeder Reactor for assessment of the orientation of the ultrasonic transducer prior to the under-sodium ultrasonic scanning for detection of any protrusion of the subassemblies. PMID:25041979

  17. Evaluation of a commercial integrating sphere setup for the determination of absolute photoluminescence quantum yields of dilute dye solutions.

    PubMed

    Würth, Christian; Lochmann, Cornelia; Spieles, Monika; Pauli, Jutta; Hoffmann, Katrin; Schüttrigkeit, Tanja; Franzl, Thomas; Resch-Genger, Ute

    2010-07-01

    The commercial availability of stand-alone setups for the determination of absolute photoluminescence quantum yields (Phi(f)) in conjunction with the increasing use of integrating sphere accessories for spectrofluorometers is expected to have a considerable influence not only on the characterization of chromophore systems for use in optical and opto-electronic devices, but also on the determination of this key parameter for (bio)analytically relevant dyes and functional luminophores. Despite the huge potential of systems measuring absolute Phi(f) values and the renewed interest in dependable data, evaluated protocols for even the most elementary case, the determination of the fluorescence quantum yield of transparent dilute solutions of small organic dyes with integrating sphere methods, are still missing. This encouraged us to evaluate the performance and sources of uncertainty of a simple commercial integrating sphere setup with dilute solutions of two of the best characterized fluorescence quantum yield standards, quinine sulfate dihydrate and rhodamine 101, strongly differing in spectral overlap between absorption and emission. Special attention is dedicated to illustrate common pitfalls of this approach, thereby deriving simple procedures to minimize measurement uncertainties and improve the comparability of data for the broad community of users of fluorescence techniques. PMID:20615286

  18. Problems determining relative and absolute ages using the small crater population

    NASA Astrophysics Data System (ADS)

    Xiao, Zhiyong; Strom, Robert G.

    2012-07-01

    The small crater populations (diameter smaller than 1 km) are widely used to date planetary surfaces. The reliability of small crater counts is tested by counting small craters at several young and old lunar surfaces, including Mare Nubium and craters Alphonsus, Tycho and Giordano Bruno. Based on high-resolution images from both the Lunar Reconnaissance Orbiter Camera and Kaguya Terrain Camera, small craters in two different diameter ranges are counted for each counting area. Large discrepancies exist in both the cumulative (absolute model ages) and relative plots for the two different size ranges of the same counting areas. The results indicate that dating planetary surfaces using small crater populations is highly unreliable because the contamination of secondaries may invalidate the results of small crater counts. A comparison of the size-frequency distributions of the small crater populations and impact ejected boulders around fresh lunar craters shows the same upturn as typical martian secondaries, which supports the argument that secondaries dominate the small crater populations on the Moon and Mars. Also, the size-frequency distributions of small rayed lunar and martian craters of probable primary origin are similar to that of the Population 2 craters on the inner Solar System bodies post-dating Late Heavy Bombardment. Dating planetary surfaces using the small crater populations requires the separation of primaries from secondaries which is extremely difficult. The results also show that other factors, such as different target properties and the subjective identification of impact craters by different crater counters, may also affect crater counting results. We suggest that dating planetary surfaces using small crater populations should be with highly cautious.

  19. Atom-chip based quantum gravimetry for the precise determination of absolute local gravity

    NASA Astrophysics Data System (ADS)

    Abend, S.

    2015-12-01

    We present a novel technique for the precise measurement of absolute local gravity based on cold atom interferometry. Atom interferometry utilizes the interference of matter waves interrogated by laser light to read out inertial forces. Today's generation of these devices typically operate with test mass samples, that consists of ensembles of laser cooled atoms. Their performance is limited by the velocity spread and finite-size of the test masses that impose systematic uncertainties at the level of a few μGal. Rather than laser cooled atoms we employ quantum degenerate ensembles, so called Bose-Einstein condensates, as ultra-sensitive probes for gravity. These sources offer unique properties in temperature as well as in ensemble size that will allow to overcome the current limitations with the next generation of sensors. Furthermore, atom-chip technologies offer the possibility to generate Bose-Einstein condensates in a fast and reliable way. We show a lab-based prototype that uses the atom-chip itself to retro-reflect the interrogation laser and thus serving as inertial reference inside the vacuum. With this setup it is possible to demonstrate all necessary steps to measure gravity, including the preparation of the source, spanning an interferometer as well as the detection of the output signal, within an area of 1 cm3 right below the atom-chip and to analyze relevant systematic effects. In the framework of the center of excellence geoQ a next generation device is under construction at the Institut für Quantenoptik, that will allow for in-field measurements. This device will feature a state-of-the-art atom-chip source with a high-flux of ultra-cold atoms at a repetition rate of 1-2 Hz. In cooperation with the Müller group at the Institut für Erdmessung the sensor will be characterized in the laboratory first, to be ultimately employed in campaigns to measure the Fennoscandian uplift at the level of 1 μGal. The presented work is part of the center of

  20. Precision laser surveying instrument using atmospheric turbulence compensation by determining the absolute displacement between two laser beam components

    DOEpatents

    Veligdan, James T.

    1993-01-01

    Atmospheric effects on sighting measurements are compensated for by adjusting any sighting measurements using a correction factor that does not depend on atmospheric state conditions such as temperature, pressure, density or turbulence. The correction factor is accurately determined using a precisely measured physical separation between two color components of a light beam (or beams) that has been generated using either a two-color laser or two lasers that project different colored beams. The physical separation is precisely measured by fixing the position of a short beam pulse and measuring the physical separation between the two fixed-in-position components of the beam. This precisely measured physical separation is then used in a relationship that includes the indexes of refraction for each of the two colors of the laser beam in the atmosphere through which the beam is projected, thereby to determine the absolute displacement of one wavelength component of the laser beam from a straight line of sight for that projected component of the beam. This absolute displacement is useful to correct optical measurements, such as those developed in surveying measurements that are made in a test area that includes the same dispersion effects of the atmosphere on the optical measurements. The means and method of the invention are suitable for use with either single-ended systems or a double-ended systems.

  1. 3D absolute hypocentral determination - 13 years of seismicity in Ecuadorian subduction zone

    NASA Astrophysics Data System (ADS)

    Font, Yvonne; Segovia, Monica; Theunissen, Thomas

    2010-05-01

    of azimuthal coverage, record frequency and signal quality. Then, we define 5 domains: Offshore/coast, North-Andean margin, Volcanic chain, Southern Ecuador, and a domain deeper than 50 km. We process earthquake location only if at least 3 proximal stations exist in the event's domain. This data selection allows providing consistent quality location. The third step consists in improving the 3D MAXI technique that is well adapted to perform absolute earthquake location in velocity model presenting strong lateral Vp heterogeneities. The resulting catalogue allows specifying the deformation in the subduction system. All seismicity previously detected before trench occurs indeed between the trench and the coastal range. South of 0°, facing the subducting Carnegie Ridge, the seismicity aligns along the interplate seismogenic zone between an updip limit shallower than ~8 km and a downdip limit that reaches up to 50 km depth. The active seismogenic zone is interrupted by a gap that extends right beneath the coastal range. At these latitudes, a diffuse intraplate deformation also affects the subducting plate, probably induced by the locally thickened lithosphere flexure. Between the trench and the coast, earthquake distribution clearly defines a gap, which size is comparable to the 1942 M7.9 asperity (ellipse of axes ~55/35 km). A slab is clearly defines and dips around 25 to 30°. The slab seismicity is systematically interrupted between 100-170 km, approximately beneath the volcanic chain. North of 0°, i.e. in the megathrust earthquake domain, the interseismic activity is clearly reduced. The interplate distribution seems to gather along alignments perpendicular to the trench attesting probably of the margin segmentation. The North Andean overriding margin is undergoing active deformation, especially at the location where the Andean Chain strike changes of direction. At these latitudes, no earthquake occurs deeper than 100 km depth.

  2. Determining the importance of model calibration for forecasting absolute/relative changes in streamflow from LULC and climate changes

    USGS Publications Warehouse

    Niraula, Rewati; Meixner, Thomas; Norman, Laura M.

    2015-01-01

    Land use/land cover (LULC) and climate changes are important drivers of change in streamflow. Assessing the impact of LULC and climate changes on streamflow is typically done with a calibrated and validated watershed model. However, there is a debate on the degree of calibration required. The objective of this study was to quantify the variation in estimated relative and absolute changes in streamflow associated with LULC and climate changes with different calibration approaches. The Soil and Water Assessment Tool (SWAT) was applied in an uncalibrated (UC), single outlet calibrated (OC), and spatially-calibrated (SC) mode to compare the relative and absolute changes in streamflow at 14 gaging stations within the Santa Cruz River Watershed in southern Arizona, USA. For this purpose, the effect of 3 LULC, 3 precipitation (P), and 3 temperature (T) scenarios were tested individually. For the validation period, Percent Bias (PBIAS) values were >100% with the UC model for all gages, the values were between 0% and 100% with the OC model and within 20% with the SC model. Changes in streamflow predicted with the UC and OC models were compared with those of the SC model. This approach implicitly assumes that the SC model is “ideal”. Results indicated that the magnitude of both absolute and relative changes in streamflow due to LULC predicted with the UC and OC results were different than those of the SC model. The magnitude of absolute changes predicted with the UC and SC models due to climate change (both P and T) were also significantly different, but were not different for OC and SC models. Results clearly indicated that relative changes due to climate change predicted with the UC and OC were not significantly different than that predicted with the SC models. This result suggests that it is important to calibrate the model spatially to analyze the effect of LULC change but not as important for analyzing the relative change in streamflow due to climate change. This

  3. Assays for Determination of Protein Concentration.

    PubMed

    Olson, Bradley J S C

    2016-01-01

    Biochemical analysis of proteins relies on accurate quantification of protein concentration. Detailed in this appendix are some commonly used methods for protein analysis, e.g., Lowry, Bradford, bicinchoninic acid (BCA), UV spectroscopic, and 3-(4-carboxybenzoyl)quinoline-2-carboxaldehyde (CBQCA) assays. The primary focus of this report is assay selection, emphasizing sample and buffer compatibility. The fundamentals of generating protein assay standard curves and of data processing are considered, as are high-throughput adaptations of the more commonly used protein assays. Also included is a rapid, inexpensive, and reliable BCA assay of total protein in SDS-PAGE sample buffer that is used for equal loading of SDS-PAGE gels. © 2016 by John Wiley & Sons, Inc. PMID:27248579

  4. Toxicity Data to Determine Refrigerant Concentration Limits

    SciTech Connect

    Calm, James M.

    2000-09-30

    This report reviews toxicity data, identifies sources for them, and presents resulting exposure limits for refrigerants for consideration by qualified parties in developing safety guides, standards, codes, and regulations. It outlines a method to calculate an acute toxicity exposure limit (ATEL) and from it a recommended refrigerant concentration limit (RCL) for emergency exposures. The report focuses on acute toxicity with particular attention to lethality, cardiac sensitization, anesthetic and central nervous system effects, and other escape-impairing effects. It addresses R-11, R-12, R-22, R-23, R-113, R-114, R-116, R-123, R-124, R-125, R-134, R-134a, R-E134, R-141b, R-142b, R-143a, R-152a, R-218, R-227ea, R-236fa, R-245ca, R-245fa, R-290, R-500, R-502, R-600a, R-717, and R-744. It summarizes additional data for R-14, R-115, R-170 (ethane), R-C318, R-600 (n-butane), and R-1270 (propylene) to enable calculation of limits for blends incorporating them. The report summarizes the data a nd related safety information, including classifications and flammability data. It also presents a series of tables with proposed ATEL and RCL concentrations-in dimensionless form and the latter also in both metric (SI) and inch-pound (IP) units of measure-for both the cited refrigerants and 66 zerotropic and azeotropic blends. They include common refrigerants, such as R-404A, R-407C, R-410A, and R-507A, as well as others in commercial or developmental status. Appendices provide profiles for the cited single-compound refrigerants and for R-500 and R-502 as well as narrative toxicity summaries for common refrigerants. The report includes an extensive set of references.

  5. Absolute ages from crater statistics: Using radiometric ages of Martian samples for determining the Martian cratering chronology

    NASA Technical Reports Server (NTRS)

    Neukum, G.

    1988-01-01

    In the absence of dates derived from rock samples, impact crater frequencies are commonly used to date Martian surface units. All models for absolute dating rely on the lunar cratering chronology and on the validity of its extrapolation to Martian conditions. Starting from somewhat different lunar chronologies, rather different Martian cratering chronologies are found in the literature. Currently favored models are compared. The differences at old ages are significant, the differences at younger ages are considerable and give absolute ages for the same crater frequencies as different as a factor of 3. The total uncertainty could be much higher, though, since the ratio of lunar to Martian cratering rate which is of basic importance in the models is believed to be known no better than within a factor of 2. Thus, it is of crucial importance for understanding the the evolution of Mars and determining the sequence of events to establish an unambiguous Martian cratering chronology from crater statistics in combination with clean radiometric ages of returned Martian samples. For the dating goal, rocks should be as pristine as possible from a geologically simple area with a one-stage emplacement history of the local formation. A minimum of at least one highland site for old ages, two intermediate-aged sites, and one very young site is needed.

  6. Determination of the specific heat capacity of a graphite sample using absolute and differential methods

    NASA Astrophysics Data System (ADS)

    Picard, Susanne; Burns, David T.; Roger, Philippe

    2007-10-01

    An experimental assembly has been constructed to measure the specific heat capacity of macroscopic graphite samples at room temperature. The same batch of graphite constitutes the core of a graphite calorimeter, which is currently being realized to measure the absorbed dose due to ionizing radiation. Two different experimental procedures have been applied. In the first method the specific heat capacity of graphite was measured directly, where its value is corrected for the influence of impurities. The second method, to our knowledge not previously applied to macroscopic samples, is based on a series of differential measurements where no correction for added impurities is needed. By its nature, the second method reduces systematic effects. The specific heat capacity of a particular graphite sample is determined to be 706.9 J K-1 kg-1 with a combined relative standard uncertainty of 9 parts in 104 at 295.15 K. The specific heat capacity of cyanoacrylate has also been determined.

  7. Absolute determination of photoluminescence quantum efficiency using an integrating sphere setup

    SciTech Connect

    Leyre, S.; Coutino-Gonzalez, E.; Hofkens, J.; Joos, J. J.; Poelman, D.; Smet, P. F.; Ryckaert, J.; Meuret, Y.; Durinck, G.; Hanselaer, P.

    2014-12-15

    An integrating sphere-based setup to obtain a quick and reliable determination of the internal quantum efficiency of strongly scattering luminescent materials is presented. In literature, two distinct but similar measurement procedures are frequently mentioned: a “two measurement” and a “three measurement” approach. Both methods are evaluated by applying the rigorous integrating sphere theory. It was found that both measurement procedures are valid. Additionally, the two methods are compared with respect to the uncertainty budget of the obtained values of the quantum efficiency. An inter-laboratory validation using the two distinct procedures was performed. The conclusions from the theoretical study were confirmed by the experimental data.

  8. Absolute np and pp cross section determinations aimed at improving the standard for cross section measurements

    SciTech Connect

    Laptev, Alexander B; Haight, Robert C; Tovesson, Fredrik; Arndt, Richard A; Briscoe, William J; Paris, Mark W; Strakovsky, Igor I; Workman, Ron L

    2010-01-01

    Purpose of present research is a keeping improvement of the standard for cross section measurements of neutron-induced reactions. The cross sections for np and pp scattering below 1000 MeV are determined based on partial-wave analyses (PW As) of nucleon-nucleon scattering data. These cross sections are compared with the most recent ENDF/B-V11.0 and JENDL-4.0 data files, and the Nijmegen PWA. Also a comparison of evaluated data with recent experimental data was made to check a quality of evaluation. Excellent agreement was found between the new experimental data and our PWA predictions.

  9. Absolute np and pp Cross Section Determinations Aimed At Improving The Standard For Cross Section Measurements

    SciTech Connect

    Laptev, A. B.; Haight, R. C.; Tovesson, F.; Arndt, R. A.; Briscoe, W. J.; Paris, M. W.; Strakovsky, I. I.; Workman, R. L.

    2011-06-01

    Purpose of present research is a keeping improvement of the standard for cross section measurements of neutron-induced reactions. The cross sections for np and pp scattering below 1 GeV are determined based on partial-wave analyses (PWAs) of nucleon-nucleon scattering data. These cross sections are compared with the most recent ENDF/B-VII.0 and JENDL-4.0 data files, and the Nijmegen PWA. Also a comparison of evaluated data with recent experimental data was made to check a quality of evaluation. Excellent agreement was found between the new experimental data and our PWA predictions.

  10. Novelty is not enough: laser-evoked potentials are determined by stimulus saliency, not absolute novelty

    PubMed Central

    Ronga, I.; Valentini, E.; Mouraux, A.

    2013-01-01

    Event-related potentials (ERPs) elicited by transient nociceptive stimuli in humans are largely sensitive to bottom-up novelty induced, for example, by changes in stimulus attributes (e.g., modality or spatial location) within a stream of repeated stimuli. Here we aimed 1) to test the contribution of a selective change of the intensity of a repeated stimulus in determining the magnitude of nociceptive ERPs, and 2) to dissect the effect of this change of intensity in terms of “novelty” and “saliency” (an increase of stimulus intensity is more salient than a decrease of stimulus intensity). Nociceptive ERPs were elicited by trains of three consecutive laser stimuli (S1-S2-S3) delivered to the hand dorsum at a constant 1-s interstimulus interval. Three, equally spaced intensities were used: low (L), medium (M), and high (H). While the intensities of S1 and S2 were always identical (L, M, or H), the intensity of S3 was either identical (e.g., HHH) or different (e.g., MMH) from the intensity of S1 and S2. Introducing a selective change in stimulus intensity elicited significantly larger N1 and N2 waves of the S3-ERP but only when the change consisted in an increase in stimulus intensity. This observation indicates that nociceptive ERPs do not simply reflect processes involved in the detection of novelty but, instead, are mainly determined by stimulus saliency. PMID:23136349

  11. Absolute Bragg wavelength and dispersion determination in dispersive incoherent OFDR interrogators

    NASA Astrophysics Data System (ADS)

    Clement, J.; Torregrosa, G.; Hervás, J.; Fernández-Pousa, C. R.

    2016-05-01

    We report on an incoherent OFDR interrogator of FBG arrays based on the concept of dispersive wavelength to time delay mapping. The system is specifically designed to show stability to environmental thermal variations by the incorporation of a composite dispersive delay and weak broadband reflectors for delay and dispersion monitoring. Dispersion is imparted by the combination of a fiber coil and an athermally-packaged chirped fiber Bragg grating for dispersion compensation. Using differential measurements over a single acquisition trace, the values of Bragg wavelengths and dispersion are determined from the delays experienced by the FBGs and by additional reference wavelengths reflected in the broadband reflectors. The results show maximum deviations of 20 pm and 0.2 ps/nm with respect to OSA measurements of Bragg wavelengths and nominal dispersion values, respectively.

  12. [HPLC enantioseparation, absolute configuration determination and anti-HIV-1 activity of (±)-F18 enantiomers].

    PubMed

    Zhang, Lei-lei; Xue, Hai; Li, Li; Lu, Xiao-fan; Chen, Zhi-wei; Lu, Gang

    2015-06-01

    Racemic (±)-F18 (10-chloromethyl-11-demethyl-12-oxo-calanolide A), an analog of nature product (+)-calanolide A, is a new anti-HIV-1 nonnucleoside reverse transcript inhibitor (NNRTI). A successful enantioseparation of (±)-F18 offering (R)-F18 and (S)-F18 was achieved by a chiral stationary phase prepared HPLC. Their absolute configurations were determined by measurement of their electronic circular dichroisms combined with modem quantum-chemical calculations. Further investigation revealed that (R)-F18 and (S)-F18 shared a similar anti-HIV activities, however, (R)-F18 was more potent than (S)-F18 against wild-type virus, K101E mutation and P225H mutation pseudoviruses. PMID:26521445

  13. Improved determination of seafloor absolute magnetization from uneven, near-seafloor magnetic measurements and high-resolution bathymetry

    NASA Astrophysics Data System (ADS)

    Szitkar, F.; Dyment, J.; Choi, Y.; Fouquet, Y.

    2012-12-01

    Vector magnetometers installed on deep-sea submersibles offer a unique opportunity to achieve high resolution magnetic investigations at the scale of hundred to thousand meters. Once corrected for the vehicle induced and remanent magnetization, the measurements mostly reflect variations of the topography and the submersible path - i.e. the distance between the sources and the observation points. The interesting parameter, however, is the seafloor magnetization that can be interpreted in terms of geological processes. Here we present methods to compute absolute magnetization of the seafloor by taking advantage of the uneven track of the submersible. In these methods, synthetic anomalies are computed for a unit magnetization assuming the geometry of the experiment, i.e. the source and the submersible path. The absolute magnetization is determined by a comparison between the observed anomalies and the synthetic ones along sliding windows. The coherency between the two signals gives an estimation of the quality of the determination, and the phase provides information on the magnetic polarity, and therefore the age of volcanic features. Such a method has been developed by Honsho et al. (JGR, 2009) using deep-sea submersible data only, i.e. magnetic anomaly, depth and altitude of the submersible. The synthetic anomalies are computed using 2D forward modeling, i.e. assuming the structures to be infinite in the direction perpendicular to the submersible path. The method has been applied with success to linear profiles crossing elongated structures such as mid-ocean ridges, but may fail for structures departing from the 2D assumption. The adaptation of improving multibeam systems to autonomous underwater vehicles (AUVs) has opened the way to the collection of very high resolution bathymetric data (around 2m between each measurement). This development has triggered a new strategy to explore the seafloor using manned submersibles: an AUV is operated during night time to

  14. Procoagulant and platelet-derived microvesicle absolute counts determined by flow cytometry correlates with a measurement of their functional capacity

    PubMed Central

    Ayers, Lisa; Harrison, Paul; Kohler, Malcolm; Ferry, Berne

    2014-01-01

    Background Flow cytometry is the most commonly used technology to measure microvesicles (MVs). Despite reported limitations of this technique, MV levels obtained using conventional flow cytometry have yielded many clinically relevant findings, such as associations with disease severity and ability to predict clinical outcomes. This study aims to determine if MV enumeration by flow cytometry correlates with a measurement of their functional capacity, as this may explain how flow cytometry generates clinically relevant results. Methods One hundred samples from healthy individuals and patients with obstructive sleep apnoea were analysed by conventional flow cytometry (FACSCalibur) and by three functional MV assays: Zymuphen MP-activity in which data were given as phosphatidylserine equivalent, STA® Phospholipid Procoag Assay expressed as clotting time and Endogenous Thrombin Potential (ETP) reflecting in vitro thrombin generation. Correlations were determined by Spearman correlation. Results Absolute counts of lactadherin+ procoagulant MVs generated by flow cytometry weakly correlated with the results obtained from the Zymuphen MP-activity (r=0.5370, p<0.0001); correlated with ETP (r=0.7444, p<0.0001); negatively correlated with STA® Phospholipid Procoag Assay clotting time (−0.7872, p<0.0001), reflecting a positive correlation between clotting activity and flow cytometry. Levels of Annexin V+ procoagulant and platelet-derived MVs were also associated with functional assays. Absolute counts of MVs derived from other cell types were not correlated with the functional results. Conclusions Quantitative results of procoagulant and platelet-derived MVs from conventional flow cytometry are associated with the functional capability of the MVs, as defined by three functional MV assays. Flow cytometry is a valuable technique for the quantification of MVs from different cellular origins; however, a combination of several analytical techniques may give the most comprehensive

  15. Constraints on the Mid-Continent Deformation Gravity Gradient Determined from Co-located GPS and Absolute Gravity Observations

    NASA Astrophysics Data System (ADS)

    James, T. S.; Mazzotti, S.; Mazzotti, S.; Lambert, A.

    2001-12-01

    The deformation gravity gradient (DGG) is the ratio of the time rate of change of surface gravity to vertical crustal velocity. Different processes generate different theoretical predictions of the DGG. Consequently, observational constraints on the DGG are necessary to link crustal uplift observations to satellite-derived observations of the time rate of change of the Earth's gravitational field, which will be generated by upcoming satellite missions such as GRACE. Larson and van Dam (2000) have compared secular gravity trends from 4 sites in interior North America to crustal uplift rates obtained from global point-positioning analyses of GPS observations, and found they agree, assuming a nominal DGG value appropriate to postglacial rebound of -0.15 μ Gal/mm (Wahr et al., 1995). Here we revisit and extend their analysis in order to determine the observational constraints on the DGG in mid-continent North America. We use recently published gravity rates derived from significantly more absolute gravity observations and a different GPS analysis scheme. Lambert et al. (2001) have published secular gravity rates for 7 sites in mid-continent North America, using all available absolute gravity observations and allowing for instrumental offsets. The sites, chosen to sample postglacial rebound, lie on a transect from Churchill, Manitoba, located on Hudson Bay, to North Liberty, Iowa. Four of these sites (Churchill, Flin Flon, Lac du Bonnet, and North Liberty) also feature a nearby GPS station. The GPS observations were analyzed using double differencing with Bernese 4.2, yielding 5 year time series for vertical position. The daily repeatabilities of 5 to 9 mm compare well to the weekly repeatabilities of 7-8 mm reported by Larson and van Dam (2000). A comparison of the vertical rates derived from these time series to the secular solid-surface gravity trends finds a DGG of -0.14 +/- 0.06 μ Gal/mm. This value is in good agreement with model predictions for postglacial

  16. DETERMINATION OF MINERAL FIBER CONCENTRATIONS IN FISH TISSUES

    EPA Science Inventory

    Submicroscopic inorganic particle concentrations in tissue have not been quantitatively determined in the past because of a lack of sample preparation techniques capable of achieving the sensitivity required. The determination of whether mineral fibres in water are accumulated in...

  17. Mapping the microvascular and the associated absolute values of oxy-hemoglobin concentration through turbid media via local off-set diffuse optical imaging

    NASA Astrophysics Data System (ADS)

    Chen, Chen; Klämpfl, Florian; Stelzle, Florian; Schmidt, Michael

    2014-11-01

    An imging resolution of micron-scale has not yet been discovered by diffuse optical imaging (DOI), while a superficial response was eliminated. In this work, we report on a new approach of DOI with a local off-set alignment to subvert the common boundary conditions of the modified Beer-Lambert Law (MBLL). It can resolve a superficial target in micron scale under a turbid media. To validate both major breakthroughs, this system was used to recover a subsurface microvascular mimicking structure under an skin equivalent phantom. This microvascular was included with oxy-hemoglobin solution in variant concentrations to distiguish the absolute values of CtRHb and CtHbO2 . Experimental results confirmed the feasibility of recovering the target vascular of 50 µm in diameter, and graded the values of the concentrations of oxy-hemoglobin from 10 g/L to 50 g/L absolutely. Ultimately, this approach could evolve into a non-invasive imaging system to map the microvascular pattern and the associated oximetry under a human skin in-vivo.

  18. Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Lee, Chung-Uk; Kim, Chun-Hwey; Kang, Young-Beom; Koo, Jae-Rim

    2004-12-01

    We completed the light curves of the contact binary CK Boo for 13 nights from June to July in 2004 using the 1-m reflector and BVR filters at Mt. Lemmon Optical Astronomy Observatory, and determined four new times of minimum light (three timings for primary eclipse, one for secondary). With contact mode of the 1998-version Wilson-Devinney binary model, we analyzed our BVR light curves and Rucinski & Lu (1999)'s radial-velocity ones. As a result, we found CK boo to be A-type overcontact binary (f=84%) with the low mass ratio (q=0.11) and orbital inclination (i=65°). Absolute dimensions of the system are determined from our new solution; M1=1.42M⊙, M2=0.15M⊙, R1=1.47R⊙, R2=0.59M⊙, and the distance to it is derived as about 129pc. Our distance is well consistent with that (157±33pc) from the Hipparcos trigonometric parallax within the limit of the error yielded by the latter.

  19. Absolute geomagnetic intensity determinations on Formative potsherds (1400-700 BC) from the Oaxaca Valley, Southwestern Mexico

    NASA Astrophysics Data System (ADS)

    Pétronille, Marie; Goguitchaichvili, Avto; Morales, Juan; Carvallo, Claire; Hueda-Tanabe, Yuki

    2012-11-01

    New Thellier-Coe archeointensity determinations have been measured on 15 potsherds from the Oaxaca Valley belonging to three of the four Formative Periods (Pre-Classical) of Mesoamerica, spanning 1400-700 BC. Seven of these are considered to be reliable and indicate a geomagnetic field strength of about 30 μT. This value is some 75% of the present geomagnetic field strength but is in agreement with the absolute intensities predicted from global models for this time and location, and consistent with coeval published determinations. These data thus provide significant evidence for the geomagnetic field strength in an area and for a time that was previously poorly constrained, thus providing an important contribution towards establishing a local master curve for the last 3500 yr. When established, such a curve would be a useful dating tool and also enable establishing for field strength correlations with climatic events and civilization evolutions in a region that is particularly strong in archeological and geological features. Such potential is examined for aridity events, although such observations can only be considered tentative at this stage.

  20. Method of trivalent chromium concentration determination by atomic spectrometry

    DOEpatents

    Reheulishvili, Aleksandre N.; Tsibakhashvili, Neli Ya.

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  1. Absolute single-ion solvation free energy scale in methanol determined by the lithium cluster-continuum approach.

    PubMed

    Pliego, Josefredo R; Miguel, Elizabeth L M

    2013-05-01

    Absolute solvation free energy of the lithium cation in methanol was calculated by the cluster-continuum quasichemical theory of solvation. Clusters with up to five methanol molecules were investigated using X3LYP, MP2, and MP4 methods with DZVP, 6-311+G(2df,2p), TZVPP+diff, and QZVPP+diff basis sets and including the cluster solvation through the PCM and SMD continuum models. Our calculations have determined a value of -118.1 kcal mol(-1) for the solvation free energy of the lithium, in close agreement with a value of -116.6 kcal mol(-1) consistent with the TATB assumption. Using data of solvation and transfer free energy of a pair of ions, electrode potentials and pKa, we have obtained the solvation free energy of 25 ions in methanol. Our analysis leads to a value of -253.6 kcal mol(-1) for the solvation free energy of the proton, which can be compared with the value of -263.5 kcal mol(-1) obtained by Kelly et al. using the cluster pair approximation. Considering that this difference is due to the methanol surface potential, we have estimated that it corresponds to -0.429 V. PMID:23570440

  2. Atomic-absorption determination of rhodium in chromite concentrates

    USGS Publications Warehouse

    Schnepfe, M.M.; Grimaldi, F.S.

    1969-01-01

    Rhodium is determined in chromite concentrates by atomic absorption after concentration either by co-precipitation with tellurium formed by the reduction of tellurite with tin(II) chloride or by fire assay into a gold bead. Interelement interferences in the atomic-absorption determination are removed by buffering the solutions with lanthanum sulphate (lanthanum concentration 1%). Substantial amounts of Ag, Al, Au, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ho, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn and platinum metals can be tolerated. A lower limit of approximately 0.07 ppm Rh can be determined in a 3-g sample. ?? 1969.

  3. Determination of Glucose Concentration in Yeast Culture Medium

    NASA Astrophysics Data System (ADS)

    Hara, Seiichi; Kishimoto, Tomokazu; Muraji, Masafumi; Tsujimoto, Hiroaki; Azuma, Masayuki; Ooshima, Hiroshi

    The present paper describes a sensor for measuring the glucose concentration of yeast culture medium. The sensor determines glucose concentration by measuring the yield of hydrogen peroxide produced by glucose oxidase, which is monitored as luminescence using photomultiplier. The present sensor is able to measure low glucose concentration in media in which yeast cells keep respiration state. We herein describe the system and the characteristics of the glucose sensor.

  4. Absolute Zero

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell J.; Sheibley, D.; Belloni, M.; Stamper-Kurn, D.; Vinen, W. F.

    2006-12-01

    Absolute Zero is a two hour PBS special attempting to bring to the general public some of the advances made in 400 years of thermodynamics. It is based on the book “Absolute Zero and the Conquest of Cold” by Tom Shachtman. Absolute Zero will call long-overdue attention to the remarkable strides that have been made in low-temperature physics, a field that has produced 27 Nobel Prizes. It will explore the ongoing interplay between science and technology through historical examples including refrigerators, ice machines, frozen foods, liquid oxygen and nitrogen as well as much colder fluids such as liquid hydrogen and liquid helium. A website has been established to promote the series: www.absolutezerocampaign.org. It contains information on the series, aimed primarily at students at the middle school level. There is a wealth of material here and we hope interested teachers will draw their student’s attention to this website and its substantial contents, which have been carefully vetted for accuracy.

  5. Determination of absolute configuration in chiral solvents with nuclear magnetic resonance. A combined molecular dynamics/quantum chemical study.

    PubMed

    Kessler, Jiří; Dračínský, Martin; Bouř, Petr

    2015-05-28

    Nuclear magnetic resonance (NMR) spectroscopy is omnipresent in chemical analysis. However, chirality of a molecule can only be detected indirectly by NMR, e.g., by monitoring its interaction with another chiral object. In the present study, we investigate the spectroscopic behavior of chiral molecules placed into a chiral solvent. In this case, the solvent-solute interaction is much weaker, but the application range of such NMR analysis is wider than for a specific chemical shift agent. Two alcohols and an amine were used as model systems, and differences in NMR chemical shifts dependent on the solute-solvent chirality combination were experimentally detected. Combined quantum mechanic/molecular mechanic (QM/MM) computations were applied to reveal the underlying solute-solvent interactions. NMR shielding was calculated using the density functional theory (DFT). While the experimental observations could not be reproduced quantitatively, the modeling provided a qualitative agreement and detailed insight into the essence of solvent-solute chiral interactions. The potentials of mean force (PMF) obtained using molecular dynamics (MD) and the weighted histogram analysis method (WHAM) indicate that the chiral interaction brings about differences in conformer ratios, which are to a large extent responsible for the NMR shifts. The MD results also predicted slight changes in the solvent structure, including the radial distribution function (RDF), to depend on the solvent/solute chirality combination. Apart from the conformer distribution, an effective average solvent electrostatic field was tested as another major factor contributing to the chiral NMR effect. The possibility to simulate spectral effects of chiral solvents from the first-principles opens up the way to NMR spectroscopic determination of the absolute configuration for a larger scale of compounds, including those not forming specific complexes. PMID:25411905

  6. Absolute Copy Number and Relative Change in Determinations of Human Immunodeficiency Virus Type 1 RNA in Plasma: Effect of an External Standard on Kit Comparisons

    PubMed Central

    Brambilla, Donald; Leung, Sheila; Lew, Judy; Todd, John; Herman, Steven; Cronin, Mike; Shapiro, David E.; Bremer, James; Hanson, Celine; Hillyer, George V.; McSherry, George D.; Sperling, Rhoda S.; Coombs, Robert W.; Reichelderfer, Patricia S.

    1998-01-01

    Use of a common set of human immunodeficiency virus type 1 (HIV-1) RNA standards eliminated differences among absolute HIV-1 RNA copy number estimates made with three commercially available assays. The relative changes in the viral RNA levels determined by the commercial assays were similar and were unaffected by the use of a common set of standards. PMID:9431977

  7. Simultaneous determination of the absolute configuration of twelve monosaccharide enantiomers from natural products in a single injection by UPLC-UV/MS method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In natural product chemistry, it is often crucial to determine sugar composition as well as the absolute configuration of each monosaccharide in glycosides. An ultra-performance liquid chromatography method using both photodiode array (PDA) and mass spectrometry detectors (UPLC-UV/MS) was developed....

  8. Characterizing Determinants of Risk: Concentration, Duration, and Timing of Exposure

    EPA Science Inventory

    An ongoing challenge in human health risk assessment is to determine the best approach for characterizing the risk from real-world exposures. Three major determinants characterize exposure: concentration (how much), duration (the frequency and how long), and critical timing (whe...

  9. Quantitative measurements of one-dimensional OH absolute concentration profiles in a methane/air flat flame by bi-directional laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Yu, Xin; Yang, Zhen; Peng, Jiang-Bo; Zhang, Lei; Ma, Yu-Fei; Yang, Chao-Bo; Li, Xiao-Hui; Sun, Rui

    2015-11-01

    The one-dimensional (1D) spatial distributions of OH absolute concentration in methane/air laminar premixed flat flame under different equivalence ratios at atmospheric pressure are investigated by using bi-directional laser-induced fluorescence (LIF) detection scheme combined with the direct absorption spectroscopy. The effective peak absorption cross section and the average temperature at a height of 2 mm above the burner are obtained by exciting absorption on the Q1(8) rotational line in the A2Σ+ (ʋ‧ = 0) ← X2Π (ʋ″ = 0) at 309.240 nm. The measured values are 1.86×10-15 cm2 and 1719 K, respectively. Spatial filtering and frequency filtering methods of reducing noise are used to deal with the experimental data, and the smoothing effects are also compared using the two methods. The spatial distribution regularities of OH concentration are obtained with the equivalence ratios ranging from 0.8 to 1.3. The spatial resolution of the measured result is 84 μm. Finally, a comparison is made between the experimental result of this paper and other relevant study results. Project supported by the National Key Scientific Instrument and Equipment Development Projects of China (Grant No. 2012YQ040164), the National Natural Science Foundation of China (Grant Nos. 61275127 and 91441130), the China Postdoctoral Science Foundation (Grant No. 2014M560262), and the Postdoctoral Fellowship in Heilongjiang Province, China (Grant No. LBH-Z14074).

  10. Determination of soil ionic concentration using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Pandey, Gunjan; Kumar, Ratnesh; Weber, Robert J.

    2013-05-01

    This paper presents a novel approach to estimate the soil ionic concentration by way of multi-frequency impedance measurements and using the quasi-static dielectric mixing models to infer the various ionic concentrations. In our approach, the permittivity of the soil dielectric mixture is measured using impedance spectroscopy and the results are used as input parameters to dielectric mixing models, combined with the debye-type dielectric relaxation models. We observe that the dielectric mixing models work well for low RF (radio-frequency) range and help in determining the individual ionic concentration in a multi-component soil mixture. Using the fact that the permittivity of a dielectric mixture is proportional to its impedance, we validated our approach by making multi-frequency impedance measurements of a soil mixture at different concentrations of various components. The method provides a good estimate of individual components such as air, water and ions like nitrates. While the paper is written with the perspective of soil constituent concentration determination, the underlying principle of determining individual component concentration using multi-frequency impedance measurement is applicable more generally in areas such as characterizing biological systems like pathogens, quality control of pharmaceuticals etc.

  11. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  12. Spacecraft Minimum Allowable Concentrations: Determination, Application, and Contingency Situations

    NASA Technical Reports Server (NTRS)

    Marshburn, Thomas H.; Dawson, David L. (Technical Monitor)

    1999-01-01

    This document is an outline of a presentation about the determination of minimum allowable concentrations in spacecraft. The presentation reviews the type of toxins and mechanisms to determine the acceptable concentrations of these toxic substances. The considerations for the unique situation that spaceflight entails including zero gravity, and the intense scrutiny are reviewed. The current measurement hardware is reviewed. The spacecraft atmospheres on the Shuttle, airflow, the Space Station and the EMU in respect to airflow, pressure, constituents are also summarized. Contingency situations and potential hazards are also discussed.

  13. Environmental determinants of polychlorinated biphenyl concentrations in residential carpet dust

    PubMed Central

    DellaValle, Curt T.; Wheeler, David C.; Deziel, Nicole C.; De Roos, Anneclaire J.; Cerhan, James R.; Cozen, Wendy; Severson, Richard K.; Flory, Abigail R.; Locke, Sarah J.; Colt, Joanne S.; Hartge, Patricia; Ward, Mary H.

    2014-01-01

    Polychlorinated biphenyls (PCBs), banned in the United Sates in the late 1970s, are still found in indoor and outdoor environments. Little is known about the determinants of PCB levels in homes. We measured concentrations of 5 PCB congeners (105, 138, 153, 170, 180) in carpet dust collected between 1998–2000 from 1,187 homes in four sites: Detroit, Iowa, Los Angeles, and Seattle. Home characteristics, occupational history, and demographic information were obtained by interview. We used a geographic information system to geocode addresses and determine distances to the nearest major road, freight route, and railroad, percentage of developed land, number of industrial facilities within 2 km of residences, and population density. Ordinal logistic regression was used to estimate the associations between the covariates of interest and the odds of PCB detection in each site separately. Total PCBs levels (all congeners < maximum practical quantitation limit [MPQL] vs. at least one congener ≥ MPQL to < median concentration vs. at least one congener >median concentration) were positively associated with either percentage of developed land (ORrange: 1.01-1.04 for each percentage increase) or population density (OR: 1.08 for every 1,000/mi2) in each site. The number of industrial facilities within 2 km of a home was associated with PCB concentrations; however, facility type and the direction of the association varied by site. Our findings suggest that outdoor sources of PCBs may be significant determinants of indoor concentrations. PMID:23952055

  14. Environmental determinants of polychlorinated biphenyl concentrations in residential carpet dust.

    PubMed

    DellaValle, Curt T; Wheeler, David C; Deziel, Nicole C; De Roos, Anneclaire J; Cerhan, James R; Cozen, Wendy; Severson, Richard K; Flory, Abigail R; Locke, Sarah J; Colt, Joanne S; Hartge, Patricia; Ward, Mary H

    2013-09-17

    Polychlorinated biphenyls (PCBs), banned in the United Sates in the late 1970s, are still found in indoor and outdoor environments. Little is known about the determinants of PCB levels in homes. We measured concentrations of five PCB congeners (105, 138, 153, 170, and 180) in carpet dust collected between 1998 and 2000 from 1187 homes in four sites: Detroit, Iowa, Los Angeles, and Seattle. Home characteristics, occupational history, and demographic information were obtained by interview. We used a geographic information system to geocode addresses and determine distances to the nearest major road, freight route, and railroad; percentage of developed land; number of industrial facilities within 2 km of residences; and population density. Ordinal logistic regression was used to estimate the associations between the covariates of interest and the odds of PCB detection in each site separately. Total PCB levels [all congeners < maximum practical quantitation limit (MPQL) vs at least one congener ≥ MPQL to < median concentration vs at least one congener > median concentration] were positively associated with either percentage of developed land [odds ratio (OR) range 1.01-1.04 for each percentage increase] or population density (OR 1.08 for every 1000/mi(2)) in each site. The number of industrial facilities within 2 km of a home was associated with PCB concentrations; however, facility type and direction of the association varied by site. Our findings suggest that outdoor sources of PCBs may be significant determinants of indoor concentrations. PMID:23952055

  15. Method of reliable determination of minimal lethal antibiotic concentrations.

    PubMed Central

    Pearson, R D; Steigbigel, R T; Davis, H T; Chapman, S W

    1980-01-01

    The lack of a standardized, statistically reliable method for in vitro determinations of the minimal lethal or bactericidal concentrations of antibiotics has complicated analyses of isolates of Staphylococcus aureus which appear to be inhibited but not killed by the usual concentrations of cell wall-active antibiotics. We describe a method which identifies some of the covariants involved in determinations of minimal lethal concentrations. Lethality was defined as a 99.9% reduction in the initial inoculum of bacteria after 24 h of incubation. We limited the sample volume to 0.01 ml to minimize the inhibitory effect of antibiotic and corresponding rejection values, which detected lethality with a high degree of sensitivity and specificity. When the number of colonies on subculture was equal to or less than the rejection value, the antibiotic was considered lethal for the test organism. Rejection values encompassed initial inocula from 10(5) to 10(7) colony-forming units per ml for single and duplicate samples and allowed for 1 or 5% variability in pipette volumes and errors in initial inoculum determinations. This method was used to determine the minimal lethal concentrations of semi-synthetic penicillins for S. aureau isolates, one of which was tolerant to the killing action of penicillin. Images PMID:7447427

  16. Multispectral Imaging for Determination of Astaxanthin Concentration in Salmonids

    PubMed Central

    Dissing, Bjørn S.; Nielsen, Michael E.; Ersbøll, Bjarne K.; Frosch, Stina

    2011-01-01

    Multispectral imaging has been evaluated for characterization of the concentration of a specific cartenoid pigment; astaxanthin. 59 fillets of rainbow trout, Oncorhynchus mykiss, were filleted and imaged using a rapid multispectral imaging device for quantitative analysis. The multispectral imaging device captures reflection properties in 19 distinct wavelength bands, prior to determination of the true concentration of astaxanthin. The samples ranged from 0.20 to 4.34 g per g fish. A PLSR model was calibrated to predict astaxanthin concentration from novel images, and showed good results with a RMSEP of 0.27. For comparison a similar model were built for normal color images, which yielded a RMSEP of 0.45. The acquisition speed of the multispectral imaging system and the accuracy of the PLSR model obtained suggest this method as a promising technique for rapid in-line estimation of astaxanthin concentration in rainbow trout fillets. PMID:21573000

  17. Determination of monomer concentrations in crystallizing lysozyme solutions

    NASA Technical Reports Server (NTRS)

    Wilson, L. J.; Pusey, Marc L.

    1992-01-01

    We have developed a non-optical technique for the study of aggregation in lysozyme and other protein solutions. By monitoring the rate at which lysozyme traverses a semipermeable membrane it was possible to quantitate the degree of aggregation in supersaturated solutions. Using this technique, we have measured the concentration of monomers and larger aggregates in under- and oversaturated lysozyme solutions, and in the presence of crystals, at pH 4.0 and 3 percent NaCl (0.1M NaAc). Comparison of these concentration profiles with (110) face growth rate data supports the theory that tetragonal lysozyme crystals grow by addition of preformed aggregates and not by monomer addition. The data suggest that a considerable population of aggregates larger than dimers are present at lysozyme concentrations above 22 mg/ml. Determination of dimer concentrations, and equilibrium constants for subsequent aggregation levels, are currently underway.

  18. Resolution and Determination of the Absolute Configuration of a Twisted Bis-Lactam Analogue of Tröger's Base: A Comparative Spectroscopic and Computational Study.

    PubMed

    Rúnarsson, Ögmundur Vidar; Benkhäuser, Christian; Christensen, Niels Johan; Ruiz, Josep Artacho; Ascic, Erhad; Harmata, Michael; Snieckus, Victor; Rissanen, Kari; Fristrup, Peter; Lützen, Arne; Wärnmark, Kenneth

    2015-08-21

    The first reported twisted bis-lactam, a racemic Tröger's base (TB) analogue (2), was resolved into its enantiomers on a chiral stationary phase HPLC column. The absolute configuration of (+)-2 was determined to be (R,R)-2 by comparing experimental and calculated vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra. The absolute configuration of (-)-2 was determined by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The corresponding theoretical spectra were calculated using the lowest energy conformation of (R,R)-2 and (S,S)-2 at the B3LYP/6-31G(d,p) level of theory. The absolute configuration of (+)-2 was also determined to (R,R)-2 by anomalous X-ray diffraction (AXRD) in a chiral space group P212121 using Cu-irradiation resulting in a very low Flack parameter of -0.06(3), despite the heaviest element being an oxygen atom, thus unambiguously confirming the results from the spectroscopic studies. We conclude that, for the Tröger's base (TB) analogue (2), we may rank the reliability of the individual methods for AC determination as AXRD ≫ VCD > ECD, while the synergy of all three methods provides very strong confidence in the assigned ACs of (+)-(R,R)-2 and (-)-(S,S)-2. PMID:26244379

  19. Determining controls on element concentrations in cement kiln dust leachate

    SciTech Connect

    Duchesne, J.; Reardon, E.J.

    1998-12-31

    Cement kiln dust is a waste residue composed chiefly of oxidized, anhydrous, micron-sized particles generated as a by-product of the manufacture of Portland cement. When cement kiln dust is brought into contact with water, high concentrations of potassium, sulfate and caustic alkalinity are leached. Other constitutents are leached to a lesser extent. The objective of this study was to determine whether the concentration of a given chemical constituent in kiln dust leachate is controlled by the precipitation of a secondary mineral phase or whether its concentration depends on its initial availability to the leachate solution and its subsequent diffusive flux from hydrating particles with time. Differentiating between these two distinctive styles of leaching behavior is necessary to predict the chemical composition of kiln dust leachate under dynamic flow conditions in disposal environments. Evidence of solubility control was found for Si, Ca, Mg, Al, Zn, Ti, Sr, and Ba. The concentrations of Na, Cl, K, Mo, Cr and Se, however, were found to have no solubility control. Because of the observed lack of solubility control and the particularly high concentrations of Cr and Mo in kiln dust leachate, The authors tested two additives to reduce their concentrations: (1) aluminum oxide to promote the precipitation of calcium aluminosulfates and the proxying of chromate and molybdate for sulfate in their structures; and (2) iron metal to promote the reduction of chromate and molybdate to lower valent and less soluble forms. Neither treatment had any effect on the concentration levels of Cr and Mo in solution.

  20. Real-Time Determination of Absolute Frequency in Continuous-Wave Terahertz Radiation with a Photocarrier Terahertz Frequency Comb Induced by an Unstabilized Femtosecond Laser

    NASA Astrophysics Data System (ADS)

    Minamikawa, Takeo; Hayashi, Kenta; Mizuguchi, Tatsuya; Hsieh, Yi-Da; Abdelsalam, Dahi Ghareab; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Yasui, Takeshi

    2016-05-01

    A practical method for the absolute frequency measurement of continuous-wave terahertz (CW-THz) radiation uses a photocarrier terahertz frequency comb (PC-THz comb) because of its ability to realize real-time, precise measurement without the need for cryogenic cooling. However, the requirement for precise stabilization of the repetition frequency ( f rep) and/or use of dual femtosecond lasers hinders its practical use. In this article, based on the fact that an equal interval between PC-THz comb modes is always maintained regardless of the fluctuation in f rep, the PC-THz comb induced by an unstabilized laser was used to determine the absolute frequency f THz of CW-THz radiation. Using an f rep-free-running PC-THz comb, the f THz of the frequency-fixed or frequency-fluctuated active frequency multiplier chain CW-THz source was determined at a measurement rate of 10 Hz with a relative accuracy of 8.2 × 10-13 and a relative precision of 8.8 × 10-12 to a rubidium frequency standard. Furthermore, f THz was correctly determined even when fluctuating over a range of 20 GHz. The proposed method enables the use of any commercial femtosecond laser for the absolute frequency measurement of CW-THz radiation.

  1. Accurate and absolute diffusion measurements of Rhodamine 6G in low-concentration aqueous solutions by the PGSE-WATERGATE sequence

    NASA Astrophysics Data System (ADS)

    Majer, G.; Zick, K.

    2015-04-01

    A pulsed field gradient spin-echo nuclear magnetic resonance (NMR) sequence with solvent suppression (PGSE-WATERGATE) was applied to accurately measure the diffusion coefficients of Rhodamine 6G (Rh6G) in low-concentration aqueous solutions. Three samples with Rh6G concentrations of CRh6G = 1, 4.5, and 25 μM were investigated. The precise determination of the diffusion coefficients in this low-concentration range was made possible by using a cryogenically cooled NMR probe and by the effective solvent suppression of the PGSE-WATERGATE sequence. The present results bridge the gap between diffusion data measured by fluorescence correlation spectroscopy in the single molecule limit and diffusivities obtained by pulsed field gradient NMR (PFG-NMR) without solvent suppression at higher concentrations. To further extend the concentration range, the diffusion coefficient of Rh6G was also measured on a sample with CRh6G = 410 μM by PFG-NMR. The overall concentration dependence of the Rh6G diffusion at 25 °C is discussed in terms of dimerization of the Rh6G molecules. The concentration-dependent monomer/dimer proportion is deduced from the diffusion data.

  2. Accurate and absolute diffusion measurements of Rhodamine 6G in low-concentration aqueous solutions by the PGSE-WATERGATE sequence

    SciTech Connect

    Majer, G.; Zick, K.

    2015-04-28

    A pulsed field gradient spin-echo nuclear magnetic resonance (NMR) sequence with solvent suppression (PGSE-WATERGATE) was applied to accurately measure the diffusion coefficients of Rhodamine 6G (Rh6G) in low-concentration aqueous solutions. Three samples with Rh6G concentrations of C{sub Rh6G} = 1, 4.5, and 25 μM were investigated. The precise determination of the diffusion coefficients in this low-concentration range was made possible by using a cryogenically cooled NMR probe and by the effective solvent suppression of the PGSE-WATERGATE sequence. The present results bridge the gap between diffusion data measured by fluorescence correlation spectroscopy in the single molecule limit and diffusivities obtained by pulsed field gradient NMR (PFG-NMR) without solvent suppression at higher concentrations. To further extend the concentration range, the diffusion coefficient of Rh6G was also measured on a sample with C{sub Rh6G} = 410 μM by PFG-NMR. The overall concentration dependence of the Rh6G diffusion at 25 °C is discussed in terms of dimerization of the Rh6G molecules. The concentration-dependent monomer/dimer proportion is deduced from the diffusion data.

  3. Determination of volumetric concentration of solids in vertical pipeline hydrotransport

    NASA Astrophysics Data System (ADS)

    Zych, Marcin; Hanus, Robert; Petryka, Leszek; Strzępowicz, Anna; Zych, Piotr

    2016-03-01

    This paper presents an application of radioisotopes with reference to the determination of the solid phase volumetric concentration in a hydromixture by calibration of the measuring set. It shows how the gamma absorption equipment consisting of radioactive isotopes 241Am and scintillation probe, may be applied to the measurement of solid particles volumetric concentration in a flow. It is based on fact that the intensity of a gamma beam decreases as it passes through matter. In the described experiments as solid phase the ceramic models representing natural polymetallic ocean nodules were used. The especially constructed calibration stand and obtained relation between the related intensity of radiation and mean volumetric concentration of the solid phase are presented.

  4. Determination of waterborne {sup 222}Rn concentrations using AC canisters

    SciTech Connect

    Mancini, C.; Giannelli, G.

    1995-09-01

    A method for measuring {sup 222}Rn concentration in water using charcoal canisters is presented. {sup 222}Rn is transferred within a few minutes from water contained in a 0.720 L bottle to a charcoal canister using a portable degassing unit. In the laboratory, gamma counting is performed at least 10 h after sampling to determine waterborne {sup 222}Rn concentration. The results obtained with charcoal canisters are compared to measurements made with Marinelli beakers calibrated in a comparison with liquid scintillation counting. The efficiency of transferring dissolved {sup 222}Rn in water to activated charcoal is 99% based on measurements made using Marinelli beakers. The lower limit of detection at the 95% confidence level is approximately 1 kBq m{sup -3} for a 15 min gamma count. the system was used to measure radon concentration in mineral groundwater near Rome. 7 refs., 1 fig., 1 tab.

  5. Determination of Trace Concentration in TMD Detectors using PGAA

    NASA Astrophysics Data System (ADS)

    Tomandl, I.; Viererbl, L.; Kudějová, P.; Lahodová, Z.; Klupák, V.; Fikrle, M.

    2015-05-01

    Transmutation detectors could be alternative to the traditional activation detector method for neutron fluence dosimetry at power nuclear reactors. This new method require an isotopically highly-sensitive, non-destructive in sense of compactness as well as isotopic content, precise and standardly used analytical method for trace concentration determination. The capability of Prompt Gamma-ray Activation Analysis (PGAA) for determination of trace concentrations of transmuted stable nuclides in the metallic foils of Ni, Au, Cu and Nb, which were irradiated for 21 days in the reactor core at the LVR-15 research reactor in Řež, is reported. The PGAA measurements of these activation foils were performed at the PGAA facility at Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII) in Garching.

  6. Polychlorinated biphenyls in Spanish adults: Determinants of serum concentrations

    SciTech Connect

    Agudo, Antonio; Goni, Fernando; Etxeandia, Arsenio; Vives, Asuncion; Millan, Esmeralda; Lopez, Raul; Amiano, Pilar; Ardanaz, Eva; Barricarte, Aurelio; Dolores Chirlaque, M.; Dorronsoro, Miren; Jakszyn, Paula; Larranaga, Nerea; Martinez, Carmen; Navarro, Carmen; Rodriguez, Laudina; and others

    2009-07-15

    Background: Polychlorinated biphenyls (PCBs) are persistent compounds that may pose an environmental hazard to humans, food being the main source of exposure for the general population. Objective: To measure the serum concentrations of the main PCBs in subjects from the general population in Spain, and to assess potential determinants of such concentrations. Methods: Serum was obtained from blood samples of 953 subjects aged 35-64 years, residents in five Spanish regions (three from the North and two from the South), randomly selected from the EPIC-Spain cohort. Blood collection took place during 1992-1996 and four PCB congeners (118, 138, 153 and 180) were determined by means of gas chromatography with electron-capture detection (GC-ECD). Results: The concentration of total PCBs was 459 ng/g lipids (or 3.1 {mu}g/l); the corresponding figures for PCB 153 were 186 ng/g lipids and 1.25 {mu}g/l. Men had higher values than women, PCB levels increased with age, and serum concentration of PCBs was higher in northern regions. Body mass index (BMI) was inversely related to PCB concentrations, and fish intake was the dietary factor showing the greatest association with serum PCBs. The pattern described was similar for each congener separately. Conclusions: We found concentrations similar to those reported in European countries where blood collection was carried during the same period. Regional differences within Spain are not fully explained by anthropometric or dietary factors. The inverse association with BMI suggests that in the mid-1990s there was still ongoing or recent exposure to PCBs in Spain.

  7. Determination of nitrous oxide concentrations by spectroscopic method

    NASA Astrophysics Data System (ADS)

    Mirzoeva, Larissa A.; Kiseleva, Margarete S.; Sinelnikova, Galina E.

    1990-08-01

    In the proposed paper an empirical method has been developed for determination of nitrous oxide concentration using the absorption band 2'), in proximity of), 3.87J4m, free from overlapping with absorption bands from other atmospheric gases. The transmission spectra of the atmospheric air are recorded with unresolved rotation-vibration structure. The method is inexpensive, simple and efficient It may be used for determination of enviromental pollution in homogeneous media (laboratory or production plant conditions, ground layer of atmosphere) and of unhomogeneous composistion mixtures when studying the contents of nitrous oxide along slope paths in troposphere and stratosphere.

  8. Formaldehyde concentrations in household air of asthma patients determined using colorimetric detector tubes

    PubMed Central

    Dannemiller, Karen C.; Murphy, Johnna S.; Dixon, Sherry L.; Pennell, Kelly G.; Suuberg, Eric M.; Jacobs, David E.; Sandel, Megan

    2013-01-01

    Formaldehyde is a colorless, pungent gas commonly found in homes that is a respiratory irritant, sensitizer, carcinogen and asthma trigger. Typical household sources include plywood and particleboard, cleaners, cosmetics, pesticides, and others. Development of a fast and simple measurement technique could facilitate continued research on this important chemical. The goal of this research is to apply an inexpensive short-term measurement method to find correlations between formaldehyde sources and concentration, and formaldehyde concentration and asthma control. Formaldehyde was measured using 30-minute grab samples in length-of-stain detector tubes in homes (n=70) of asthmatics in the Boston, MA area. Clinical status and potential formaldehyde sources were determined. The geometric mean formaldehyde level was 35.1 ppb and ranged from 5–132 ppb. Based on one-way ANOVA, t-tests, and linear regression, predictors of log-transformed formaldehyde concentration included absolute humidity, season, and the presence of decorative laminates, fiberglass, or permanent press fabrics (p<0.05), as well as temperature and household cleaner use (p<0.10). The geometric mean formaldehyde concentration was 57% higher in homes of children with very poorly controlled asthma compared to homes of other asthmatic children (p=0.078). This study provides a simple method for measuring household formaldehyde and suggests that exposure is related to poorly controlled asthma. PMID:23278296

  9. Formaldehyde concentrations in household air of asthma patients determined using colorimetric detector tubes.

    PubMed

    Dannemiller, K C; Murphy, J S; Dixon, S L; Pennell, K G; Suuberg, E M; Jacobs, D E; Sandel, M

    2013-08-01

    Formaldehyde is a colorless, pungent gas commonly found in homes and is a respiratory irritant, sensitizer, carcinogen, and asthma trigger. Typical household sources include plywood and particleboard, cleaners, cosmetics, pesticides, and others. Development of a fast and simple measurement technique could facilitate continued research on this important chemical. The goal of this research is to apply an inexpensive short-term measurement method to find correlations between formaldehyde sources and concentration, and formaldehyde concentration and asthma control. Formaldehyde was measured using 30-min grab samples in length-of-stain detector tubes in homes (n = 70) of asthmatics in the Boston, MA area. Clinical status and potential formaldehyde sources were determined. The geometric mean formaldehyde level was 35.1 ppb and ranged from 5 to 132 ppb. Based on one-way ANOVA, t-tests, and linear regression, predictors of log-transformed formaldehyde concentration included absolute humidity, season, and the presence of decorative laminates, fiberglass, or permanent press fabrics (P < 0.05), as well as temperature and household cleaner use (P < 0.10). The geometric mean formaldehyde concentration was 57% higher in homes of children with very poorly controlled asthma compared to homes of other asthmatic children (P = 0.078). This study provides a simple method for measuring household formaldehyde and suggests that exposure is related to poorly controlled asthma. PMID:23278296

  10. A Nonempirical Approach for Direct Determination of the Absolute Configuration of 1,2-Diols and Amino Alcohols Using Mg(II)bisporphyrin.

    PubMed

    Ikbal, Sk Asif; Dhamija, Avinash; Brahma, Sanfaori; Rath, Sankar Prasad

    2016-07-01

    We report here a simple, facile, and direct nonempirical protocol for determining the absolute stereochemistry of a variety of chiral 1,2-diols and amino alcohols at room temperature with no chemical derivatization using Mg(II)bisporphyrin as a host. Addition of excess substrates resulted in the formation of a 1:2 host-guest complex in which two substrates bind in an unusual endo-endo fashion because of interligand H-bonding within the bisporphyrin cavity leading to the formation of a unidirectional screw in the bisporphyrin moiety that allowed us an accurate absolute stereochemical determination of the chiral substrate via exciton-coupled circular dichroism (ECCD). The sign of the CD couplet has also been found to be inverted when the stereogenic center is moved by one C atom simply from the bound to an unbound functionality and thus able to discriminate between them successfully. Strong complexation of the alcoholic oxygen with Mg(II)bisporphyrin rigidifies the host-guest complex, which eventually enhances its ability to stereochemically differentiate the asymmetric center. The ECCD sign of a large number of substrates has followed consistent and predictable trends; thus, the system is widely applicable. Moreover, computational calculations clearly support the experimental observations along with the absolute stereochemistry of the chiral substrate. PMID:27231970

  11. Determination of the absolute configuration of pentacoordinate chiral phosphorus compounds in solution by using vibrational circular dichroism spectroscopy and density functional theory.

    PubMed

    Yang, Guochun; Xu, Yunjie; Hou, Jianbo; Zhang, Hui; Zhao, Yufen

    2010-02-22

    Vibrational circular dichroism (VCD) spectroscopic measurements and density functional theory (DFT) calculations have been used to obtain the absolute structural information about four sets of diastereomers of pentacoordinate spirophosphoranes derived separately from l- (or d-) valine and l- (or d-) leucine for the first time. Each compound contains three stereogenic centers: one at the phosphorus center and two at the amino acid ligands. Extensive conformational searches for the compounds have been carried out and their vibrational absorption (VA) and VCD spectra have been simulated at the B3LYP/6-311++G** level. Although both VA and VCD spectra are highly sensitive to the structural variation of the apical axis, that is, the O-P-O or N-P-O arrangement, the rotamers generated by the aliphatic amino side chains show little effect on both. The dominant experimental VCD features in the 1100-1500 cm(-1) region were found to be controlled by the chirality at the phosphorus center, whereas those at the C=O stretching region are determined by the chirality of the amino acid ligands. The good agreement between the experimental VA and VCD spectra in CDCl(3) solution and the simulated ones allows us to assign the absolute configurations of these pentacoordinate phosphorus compounds with high confidence. This study shows that the VCD spectroscopy complemented with DFT calculations is a powerful and reliable method for determining the absolute configurations and dominating conformers of synthetic phosphorus coordination complexes in solution. PMID:20077536

  12. Nanoparticle Counting: Towards Accurate Determination of the Molar Concentration

    PubMed Central

    Shang, Jing; Gao, Xiaohu

    2014-01-01

    Summary Innovations in nanotechnology have brought tremendous opportunities for the advancement of many research frontiers, ranging from electronics, photonics, energy, to medicine. To maximize the benefits of nano-scaled materials in different devices and systems, precise control of their concentration is a prerequisite. While concentrations of nanoparticles have been provided in other forms (e.g., mass), accurate determination of molar concentration, arguably the most useful one for chemical reactions and applications, has been a major challenge (especially for nanoparticles smaller than 30 nm). Towards this significant yet chronic problem, a variety of strategies are currently under development. Most of these strategies are applicable to a specialized group of nanoparticles due to their restrictions on the composition and size ranges of nanoparticles. As research and uses of nanomaterials being explored in an unprecedented speed, it is necessary to develop universal strategies that are easy to use, and compatible with nanoparticles of different sizes, compositions, and shapes. This review outlines the theories and applications of current strategies to measure nanoparticle molar concentration, discusses the advantages and limitations of these methods, and provides insights into future directions. PMID:25099190

  13. Determination of subjective similarity for pairs of masses and pairs of clustered microcalcifications on mammograms: Comparison of similarity ranking scores and absolute similarity ratings

    SciTech Connect

    Muramatsu, Chisako; Li Qiang; Schmidt, Robert A.; Shiraishi, Junji; Suzuki, Kenji; Newstead, Gillian M.; Doi, Kunio

    2007-07-15

    The presentation of images that are similar to that of an unknown lesion seen on a mammogram may be helpful for radiologists to correctly diagnose that lesion. For similar images to be useful, they must be quite similar from the radiologists' point of view. We have been trying to quantify the radiologists' impression of similarity for pairs of lesions and to establish a ''gold standard'' for development and evaluation of a computerized scheme for selecting such similar images. However, it is considered difficult to reliably and accurately determine similarity ratings, because they are subjective. In this study, we compared the subjective similarities obtained by two different methods, an absolute rating method and a 2-alternative forced-choice (2AFC) method, to demonstrate that reliable similarity ratings can be determined by the responses of a group of radiologists. The absolute similarity ratings were previously obtained for pairs of masses and pairs of microcalcifications from five and nine radiologists, respectively. In this study, similarity ranking scores for eight pairs of masses and eight pairs of microcalcifications were determined by use of the 2AFC method. In the first session, the eight pairs of masses and eight pairs of microcalcifications were grouped and compared separately for determining the similarity ranking scores. In the second session, another similarity ranking score was determined by use of mixed pairs, i.e., by comparison of the similarity of a mass pair with that of a calcification pair. Four pairs of masses and four pairs of microcalcifications were grouped together to create two sets of eight pairs. The average absolute similarity ratings and the average similarity ranking scores showed very good correlations in the first study (Pearson's correlation coefficients: 0.94 and 0.98 for masses and microcalcifications, respectively). Moreover, in the second study, the correlations between the absolute ratings and the ranking scores were also

  14. Cell for determination of tritium concentration by liquid radiometer

    SciTech Connect

    Antonenko, G.I.; Savina, V.I.; Egurneva, T.B.

    1987-02-01

    An optimized cell is described for determination of tritium concentration in the form of tritiated water by a liquid scintillation radiometer at a level of 10/sup 4/ Bq/m/sup 3/. The cell is made of Teflon and has a wall thickness of 0.8-1.0 mm. The useful capacity of the cell is 45 cm/sup 3/ (5 cm/sup 3/ of tritiated water and 40 cm/sup 3/ of ZhS-81 liquid scintillator).

  15. ET-AAS determination of aluminium in dialysis concentrates after continuous flow solvent extraction.

    PubMed

    Komárek, J; Cervenka, R; Růzicka, T; Kubán, V

    2007-11-01

    Conditions of a continuous flow extraction (CFE) of aluminium acetylacetonate in acetylacetone and aluminium 8-hydroxyquinolinate into methylisobutylketone (lengths of reaction and extraction coils, flow rates of aqueous and organic phases and their flow rate ratio, pH of aqueous phase, lengths of coils for transport of aqueous and organic phases and effect of salts) were studied. The analytical signal of the aluminium chelates present in the organic phase was measured at 309.3 nm using atomic absorption spectrometry with electrothermal atomization (ET-AAS) at the flow rate ratio F aq/F org=3 for aqueous and organic phases. The five points calibration curves were linear (R2 0.9973 and 0.9987) up to 21 microgl(-1) Al with the limits of detection of 0.3 microgl(-1) and the recovery 100+/-2% and precision of 3% at 2-10-fold dilution of the dialysis concentrates. The acetylacetonate method was applied to the determination of aluminium in real dialysis concentrates. Aluminium in concentrations 5-6 microgl(-1) (R.S.D.s 5-10% in real samples) were found and the results were in the very good agreement with those obtained by an ET-AAS using preconcentration of Al(III) on a Spheron-Salicyl chelating sorbent (absolute and relative differences were under 0.4 microgl(-1) and 8.2%, respectively). PMID:17897803

  16. [Optimization and application of method to determine plasma concentration of brucine].

    PubMed

    Wang, Dong-Yue; Chen, Jun; Cai, Bao-Chang

    2013-04-01

    The HPLC method for determining plasma concentration of brucine was optimized during the study on the effect of the extraction reagent, the extraction frequency and the volume of extraction solvent on the extraction recovery of brucine. The optimum sample treatment method was obtained in the study. Specifically, ammonia water was added, 4 mL extraction solvent (N-hexane-methylene chloride-isopropyl alcohol 65:30:5) were adopted to extract brucine for twice. The method to determine plasma concentration of brucine was applied in pharmacokinetic study to compare pharmacokinetic properties of intravenous injection (5 mg x kg(-1)) and transdermal administration (40 mg x kg(-1)) of brucine aqueous alkali. The results showed that both pharmacokinetic parameters of brucine after intravenous injection and transdermal administration were in conformity with the two-compartment model. After transdermal administration, the absolute bioavailability was calculated to be 18.72%. The optimized HPLC method can satisfy the demands of the pharmacokinetic study on brucine. PMID:23847961

  17. Absolute nutrient concentration measurements in cell culture media: (1)H q-NMR spectra and data to compare the efficiency of pH-controlled protein precipitation versus CPMG or post-processing filtering approaches.

    PubMed

    Goldoni, Luca; Beringhelli, Tiziana; Rocchia, Walter; Realini, Natalia; Piomelli, Daniele

    2016-09-01

    The NMR spectra and data reported in this article refer to the research article titled "A simple and accurate protocol for absolute polar metabolite quantification in cell cultures using q-NMR" [1]. We provide the (1)H q-NMR spectra of cell culture media (DMEM) after removal of serum proteins, which show the different efficiency of various precipitating solvents, the solvent/DMEM ratios, and pH of the solution. We compare the data of the absolute nutrient concentrations, measured by PULCON external standard method, before and after precipitation of serum proteins and those obtained using CPMG (Carr-Purcell-Meiboom-Gill) sequence or applying post-processing filtering algorithms to remove, from the (1)H q-NMR spectra, the proteins signal contribution. For each of these approaches, the percent error in the absolute value of every measurement for all the nutrients is also plotted as accuracy assessment. PMID:27331118

  18. Synchrotron radiation determination of elemental concentrations in coal

    USGS Publications Warehouse

    Chen, J.R.; Martys, N.; Chao, E.C.T.; Minkin, J.A.; Thompson, C.L.; Hanson, A.L.; Kraner, H.W.; Jones, K.W.; Gordon, B.M.; Mills, R.E.

    1984-01-01

    The variations with depth of the elemental concentrations in vitrinites in a series of vitrites have been determined using radiation from the Cornell high energy synchrotron source. All of the vitrites were selected from a single drill core sample of coal from the Emery coalfield, Utah. The results are compared with similar determinations using the Heidelberg proton microprobe. The advantages and disadvantages of the two techniques are discussed. Results are reported for S, Ca, Ti, Fe, Zn, Br, and Sr. For example, it is found that Fe increases from top to bottom of the coal bed in contrast to S, which decreases from top to bottom of the bed. Other features of the two data sets are also described. ?? 1984.

  19. Determination of relative and absolute photoionization cross-sections in multiply-charged Ba^n+ Ions

    NASA Astrophysics Data System (ADS)

    Bizau, J.-M.; Cubaynes, D.; Esteva, J. M.; Wuilleumier, F. J.; Marmoret, R.; Petrault, L.; Remond, C.; Couillaud, C.; Compant La Fontaine, A.; Blancard, C.; Hitz, D.; Ludwig, P.; Deshmukh, P. C.; Zhou, H.-L.; Manson, S. T.

    2001-05-01

    Following our first photoionization measurements for the multiply-charged Xe^n+ [1] and Ba^2+ [2] ions, we introduced several modifications in the experimental set-up to allow us to measure absolute cross sections for multiply-charged ions. Photoionization studies of barium ions up to Ba^6+ were performed using synchrotron radiation emitted by an undulator of the Super ACO storage ring in Orsay and an ECR ion source. Collapse of the 4f (ɛ f) orbitals has been observed to occur faster than for Xe^n+: the relative intensity of transitions to continuum states is negligible already for Ba^3+ ions, discrete transitions to 4d^95s^25p^mnf states then dominating the measured spectra. The experimental results are in good agreement with the results of MCDF calculations for the discrete transitions and, in Ba^2+, with RRPA calculations for transitions to continuum states. 1. J.-M. Bizau et al., Phys. Rev. Lett. 84, 435 (2000). 2. J.-M. Bizau et al., Bull. Am. Phys. Soc. 45, 61 (2000).

  20. Determinants of 25-Hydroxyvitamin D Concentrations in Infants and Toddlers

    PubMed Central

    Michel, Hilary; Olabopo, Flora; Wang, Li; Nucci, Anita; Greenspan, Susan L; Rajakumar, Kumaravel

    2015-01-01

    Background Resurgence of rickets and recognition of excessive prevalence of hypovitaminosis D among all age groups in the western hemisphere have refocused attention on vitamin D nutrition. Objective To examine the prevalence of hypovitaminosis D [25-hydroxyvitamin D [25(OH)D] <30ng/mL] and characterize the determinants of 25(OH)D concentrations in 8- to 24-month-old healthy infants and toddlers living in Pittsburgh, Pennsylvania. Methods Serum 25(OH)D concentrations were measured and dietary intake of vitamin D, mode of feeding, summertime sun exposure characteristics, and skin color (sun-reactive skin type and melanin index) were assessed. Results A total of 111 healthy 8- to 24-month-old children (mean age [±SD] 14.4 [±3.5] months; male, 51%; black, 67%) were studied. Serum 25(OH)D concentration was <30 ng/mL in 16% (n=18) of the children. Median (interquartile) 25(OH)D concentration was lower in children who were ≥ 13 months vs. <13 months of age [35 (31, 40.5) vs. 40 (35.8, 44.3) ng/mL, p=0.013]; with sun-reactive skin type IV and V vs. I, II, and III [36 (31, 41) vs. 44 (36.5, 48.5) ng/mL, p=0.001]; and examined during fall/winter vs. spring/summer [35.5 (32.5, 38.5) vs. 39 (32.5, 44) ng/mL, p=0.05]. Age and skin type were significant independent predictors of 25(OH)D. Conclusions Concentrations of 25(OH)D tend to be lower in infants and toddlers during fall/winter, and in children who are older (≥13 months vs. <13 months of age) and have darker skin tone. Benefits of enhancement of 25(OH)D concentrations during fall/winter and in children with higher sun-reactive skin type need further exploration. PMID:26417213

  1. Determination of chlorophyll-a concentration under desertic dust.

    NASA Astrophysics Data System (ADS)

    Brajard, Julien; Diouf, Daouda; Brehmer, Patrice; Crépon, Michel; Lazar, Alban; Machu, Eric; Thiria, Sylvie; Capet, Xavier

    2015-04-01

    One major challenge in ocean colour remote sensing is the so-called atmospheric correction. It consists in removing the atmospheric signal from the signal measured from space by a radiometer. If an accurate atmospheric correction is performed, it is thus possible to invert the water-leaving reflectance signal to estimate in-water properties such as the chlorophyll-a concentration. Ocean colour data centers proposed a standard atmospheric correction scheme specific to the sensor they processed (SeaWiFS, MERIS, MODIS, VIIRS, …). They are accurate in most situations (open ocean waters, weakly absorbing aeorols) but fail in some specific cases such as the presence of desertic dust in the atmosphere. In some region, they can lead to exclude large regions of the image from the treatment. In this work, we propose an algorithm to perform the atmospheric correction and to determine the chlorophyll-a concentration under desertic dust. This algorithm, called SOM-NV, is a combination of a classification of the aerosol type using a self-organizing map and an inversion scheme called NeuroVaria. It has been applied to the Senegalo-Mauritanean upwelling using SeaWiFS, MODIS and VIIRS data. The results of SOM-NV have been compared with in-situ measurements (HPLC and microscope) sampled during the UPSEN (UPwelling SENegal) campaigns in 2012 and 2013.

  2. Towards determination of absolute molar mass of cellulose polymer by size exclusion chromatography with mulitple angle laser light scattering detection.

    PubMed

    Pawcenis, Dominika; Thomas, Jacob L; Łojewski, Tomasz; Milczarek, Jakub M; Łojewska, Joanna

    2015-08-28

    The study focuses on determination of a set of crucial parameters for molar mass calculation of cellulose from the results of size exclusion chromatography coupled with multiple angle laser light scattering (MALLS) and differential refractive index (DRI) detectors. In the present work, cellulose has been derivatised to obtain cellulose tricarbanilate (CTC) soluble in tetrahydrofuran (THF). The parameters of Rayleigh scattering in the MALLS detector: refractive index increment (dn/dc) and second virial coefficient (A2) of CTC in THF were determined for laser wavelength 658nm. In order to avoid errors resulting from cellulose derivatisation by-products present in the CTC solution, the so called "on-line" method of measuring dn/dc and A2 was applied. Based on the A2 determination, its influence on cellulose molar mass calculations and cellulose molecular dimensions were critically assessed. The latter includes evaluation of artificially aged cellulose towards conceivable branching by conformation plot analysis. PMID:26210115

  3. Absolute determination of power density in the VVER-1000 mock-up on the LR-0 research reactor.

    PubMed

    Košt'ál, Michal; Švadlenková, Marie; Milčák, Ján

    2013-08-01

    The work presents a detailed comparison of calculated and experimentally determined net peak areas of selected fission products gamma lines. The fission products were induced during a 2.5 h irradiation on the power level of 9.5 W in selected fuel pins of the VVER-1000 Mock-Up. The calculations were done with deterministic and stochastic (Monte Carlo) methods. The effects of different nuclear data libraries used for calculations are discussed as well. The Net Peak Area (NPA) may be used for the determination of fission density across the mock-up. This fission density is practically identical to power density. PMID:23665766

  4. A whole rock absolute paleointensity determination of dacites from the Duffer Formation (ca. 3.467 Ga) of the Pilbara Craton, Australia: An impossible task?

    NASA Astrophysics Data System (ADS)

    Herrero-Bervera, Emilio; Krasa, David; Van Kranendonk, Martin J.

    2016-09-01

    We have conducted a whole-rock type magnetic and absolute paleointensity determination of the red dacite of the Duffer Formation from the Pilbara Craton, Australia. The age of the dated rock unit is 3467 ± 5 Ma (95% confidence). Vector analyses results of the step-wise alternating field demagnetization (NRM up to 100 mT) and thermal demagnetization (from NRM up to 650 °C) yield three components of magnetization. Curie point determinations indicate three characteristic temperatures, one at 150-200 °C, a second one at ∼450 °C and a third one at ∼580 °C. Magnetic grain-size experiments were performed on small specimens with a variable field translation balance (VFTB). The coercivity of remanence (Hcr) suggests that the NRM is carried by low-coercivity grains that are associated with a magnetite fraction as is shown by the high-temperature component with blocking temperatures above 450 °C and up to at least 580 °C. The ratios of the hysteresis parameters plotted as a modified Day diagram show that most grain sizes are scattered within the Single Domain (SD) and the Superparamagnetic and Single Domain SP-SD domain ranges. In addition to the rock magnetic experiments we have performed absolute paleointensity experiments on the samples using the modified Thellier-Coe double heating method to determine the paleointensities. Partial-TRM (p-TRM) checks were performed systematically to document magnetomineralogical changes during heating. The temperature was incremented by steps of 50 °C between room temperature and 590 °C. The paleointensity determinations were obtained from the slope of Arai diagrams. Our paleointensity results indicate that the paleofield obtained was ∼6.4 ± 0.68 (N = 11) micro-Teslas with a Virtual Dipole Moment (VDM) of 1.51 ± 0.81 × 1022 Am2, from a medium-to high-temperature component ranging from 300 to 590 °C that has been interpreted to be the oldest magnetization yet recorded in paleomagnetic studies of the Duffer Formation. The

  5. Determinants of plasma concentrations of perfluoroalkyl substances in pregnant Norwegian women

    PubMed Central

    Whitworth, KW; Ydersbond, TA; Haug, LS; Haugen, M; Knutsen, HK; Thomsen, C; Meltzer, HM; Becher, G; Sabaredzovic, A; Hoppin, JA; Eggesbø, M; Longnecker, MP

    2013-01-01

    was associated with plasma PFOS, PFOA, PFHxS, and PFNA concentration increases of 7.2%, 3.3%, 5.8% and 9.8%, respectively, resulting in small, although non-trivial absolute changes in PFAS concentrations. Conclusion The history of previous pregnancies and breastfeeding were the most important determinants of PFASs in this sample of pregnant women. PMID:23419425

  6. Measurement of the B-->pi l nu branching fraction and determination of absolute value of V(ub) with tagged B mesons.

    PubMed

    Aubert, B; Barate, R; Bona, M; Boutigny, D; Couderc, F; Karyotakis, Y; Lees, J P; Poireau, V; Tisserand, V; Zghiche, A; Grauges, E; Palano, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Gill, M S; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lynch, G; Mir, L M; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Wenzel, W A; del Amo Sanchez, P; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Morgan, S E; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schroeder, T; Steinke, M; Boyd, J T; Burke, J P; Cottingham, W N; Walker, D; Cuhadar-Donszelmann, T; Fulsom, B G; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Khan, A; Kyberd, P; Saleem, M; Sherwood, D J; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Best, D S; Bondioli, M; Bruinsma, M; Chao, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Mommsen, R K; Roethel, W; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Long, O; Shen, B C; Wang, K; Zhang, L; Hadavand, H K; Hill, E J; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dvoretskii, A; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Ruddick, W O; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Chen, A; Eckhart, E A; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Petzold, A; Spaan, B; Brandt, T; Klose, V; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Grenier, P; Latour, E; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Brandenburg, G; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Flack, R L; Nash, J A; Nikolich, M B; Panduro Vazquez, W; Behera, P K; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gritsan, A V; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Davier, M; Grosdidier, G; Höcker, A; Le Diberder, F; Lepeltier, V; Lutz, A M; Oyanguren, A; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Stocchi, A; Wang, W F; Wormser, G; Cheng, C H; Lange, D J; Wright, D M; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; George, K A; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; Di Lodovico, F; Menges, W; Sacco, R; Cowan, G; Flaecher, H U; Hopkins, D A; Jackson, P S; McMahon, T R; Ricciardi, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; Naisbit, M T; Williams, J C; Yi, J I; Chen, C; Hulsbergen, W D; Jawahery, A; Lae, C K; Roberts, D A; Simi, G; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Saremi, S; Staengle, H; Cowan, R; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Kim, H; McLachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; Cavallo, N; De Nardo, G; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M; Raven, G; Snoek, H L; Jessop, C P; Losecco, J M; Allmendinger, T; Benelli, G; Gan, K K; Honscheid, K; Hufnagel, D; Jackson, P D; Kagan, H; Kass, R; Rahimi, A M; Ter-Antonyan, R; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Benayoun, M; Chauveau, J; Briand, H; David, P; Del Buono, L; de la Vaissière, Ch; Hamon, O; Hartfiel, B L; John, M J J; Leruste, Ph; Malclès, J; Ocariz, J; Roos, L; Therin, G; Gladney, L; Panetta, J; Biasini, M; Covarelli, R; Angelini, C; Batignani, G; Bettarini, S; Bucci, F; Calderini, G; Carpinelli, M; Cenci, R; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Judd, D; Wagoner, D E; Biesiada, J; Danielson, N; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Bellini, F; Cavoto, G; D'Orazio, A; del Re, D; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Safai Tehrani, F; Voena, C; Ebert, M; Schröder, H; Waldi, R; Adye, T; De Groot, N; Franek, B; Olaiya, E O; Wilson, F F; Aleksan, R; Emery, S; Gaidot, A; Ganzhur, S F; Hamel de Monchenault, G; Kozanecki, W; Legendre, M; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Cristinziani, M; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Halyo, V; Hast, C; Hryn'ova, T; Innes, W R; Kelsey, M H; Kim, P; Leith, D W G S; Li, S; Luitz, S; Luth, V; Lynch, H L; MacFarlane, D B; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; van Bakel, N; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Roat, C; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Satpathy, A; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Della Ricca, G; Dittongo, S; Lanceri, L; Vitale, L; Azzolini, V; Martinez-Vidal, F; Banerjee, Sw; Bhuyan, B; Brown, C M; Fortin, D; Hamano, K; Kowalewski, R; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Cheng, B; Dasu, S; Datta, M; Flood, K T; Hollar, J J; Kutter, P E; Mellado, B; Mihalyi, A; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Yu, Z; Neal, H

    2006-11-24

    We report a measurement of the B-->pi l nu branching fraction based on 211 fb(-1) of data collected with the BABAR detector. We use samples of B0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B(0)-->pi- l+ nu) = (1.33+/-0.17stat+/-0.11syst) x 10(-4). We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element absolute value V(ub) by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find absolute value V(ub) = (4.5+/-0.5stat+/-0.3syst(+0.7) -0.5FF x 10(-3), where the last error is due to the normalization of the form factor. PMID:17155736

  7. Absolute paleointensity determinations by using of conventional double-heating and multispecimen approaches on a Pliocene lava flow sequence from the Lesser Caucasus

    NASA Astrophysics Data System (ADS)

    Goguitchaichvili, Avto; Caccavari, Ana; Calvo-Rathert, Manuel; Morales, Juan; Solano, Miguel Cervantes; Vashakidze, Goga; Huaiyu, He; Vegas, Néstor

    2016-08-01

    We report 28 successful Thellier type absolute geomagnetic paleointensity determinations from a Pleistocene lava sequence composed of 39 successive flows in the Djavakheti Highland (Lesser Caucasus, Georgia). Additionally, multispecimen technique provided the estimation of geomagnetic field strength for 12 independent cooling units. Paleointensity studies were performed using both Thellier type double heating and multispecimen techniques. Samples selection was mainly based on uni-vectorial remanent magnetization, thermal stability and domain size of the samples. Flow-mean Thellier paleointensity values range from 16.3 ± 5.2 to 71.0 ± 0.3 μT, while intensities obtained using multispecimen approach vary from17.2 ± 2.3 to 69.3 ± 7.9 μT. One of the flows is located near a possible discontinuity in the sequence and yields a rather low Thellier absolute intensity (16.3 ± 5.2) suggesting a transitional regime and the onset of the Matuyama-Olduvai polarity transition, which does not appear on the directional record. Multispecimen paleointensities from the same flow, however, yield higher, close to present day values which makes untenable the hypothesis of occurrence of transitional field. Thus the whole sequence was emplaced in a short time between the Olduvai chron and 1.73 ± 0.03 Ma, as suggested by available radiometric and paleomagnetic data (Caccavari et al., 2014).

  8. Determination of critical assembly absolute power using post-irradiation activation measurement of week-lived fission products.

    PubMed

    Košťál, Michal; Švadlenková, Marie; Milčák, Ján; Rypar, Vojtěch; Koleška, Michal

    2014-07-01

    The work presents a detailed comparison of calculated and experimentally determined net peak areas of longer-living fission products after 100 h irradiation on a reactor with power of ~630 W and several days cooling. Specifically the nuclides studied are (140)Ba, (103)Ru, (131)I, (141)Ce, (95)Zr. The good agreement between the calculated and measured net peak areas, which is better than in determination using short lived (92)Sr, is reported. The experiment was conducted on the VVER-1000 mock-up installed on the LR-0 reactor. The Monte Carlo approach has been used for calculations. The influence of different data libraries on results of calculation is discussed as well. PMID:24566373

  9. Determination of uranium and thorium concentrations in unprocessed soil samples.

    PubMed

    Lazo, E N; Roessler, G S; Berven, B A

    1991-08-01

    An assay technique that directly determines the amount of 238U and 232Th in unprocessed, bulk soil samples has been developed. In this technique, a sample consisting of a 125-mL plastic bottle full of contaminated, moist, unprocessed soil is irradiated with gamma rays from 57Co. Induced U and Th K alpha fluorescent x rays are detected using a high-purity intrinsic germanium planar detector. Because of sample irradiation geometry, the fluorescent x-ray peaks lie on top of a large Compton backscatter peak. Spectral data are first fit to a combination polynomial and ERFc-step-function background that is subtracted from the peak data. The remaining peak data are fit to a Voigt Profile to properly determine peak area. The Voigt Profile, which is the convolution of the Gaussian response of the detector system and the Lorentzian energy distribution of x rays, describes the spectral peak better than a simple Gaussian distribution. A mathematical point-node model of the source-target-detector system, which includes fluorescent x-ray production by singly scattered Compton gamma s, calculates the predicted x-ray peak area per Bq cm-3 of target contamination. Soil attenuation coefficients, which are measured for each sample, are used by the model to properly transport gamma s and x rays through the soil sample. The sample 238U and 232Th concentrations are then calculated by dividing the measured peak areas by the model-predicted peak areas per Bq cm-3. No "soil standards," no assumptions about progeny equilibrium, and no sample preparation are required for this technique. PMID:1856084

  10. Using a Novel Absolute Ontogenetic Age Determination Technique to Calculate the Timing of Tooth Eruption in the Saber-Toothed Cat, Smilodon fatalis

    PubMed Central

    Wysocki, M. Aleksander; Feranec, Robert S.; Tseng, Zhijie Jack; Bjornsson, Christopher S.

    2015-01-01

    Despite the superb fossil record of the saber-toothed cat, Smilodon fatalis, ontogenetic age determination for this and other ancient species remains a challenge. The present study utilizes a new technique, a combination of data from stable oxygen isotope analyses and micro-computed tomography, to establish the eruption rate for the permanent upper canines in Smilodon fatalis. The results imply an eruption rate of 6.0 millimeters per month, which is similar to a previously published average enamel growth rate of the S. fatalis upper canines (5.8 millimeters per month). Utilizing the upper canine growth rate, the upper canine eruption rate, and a previously published tooth replacement sequence, this study calculates absolute ontogenetic age ranges of tooth development and eruption in S. fatalis. The timing of tooth eruption is compared between S. fatalis and several extant conical-toothed felids, such as the African lion (Panthera leo). Results suggest that the permanent dentition of S. fatalis, except for the upper canines, was fully erupted by 14 to 22 months, and that the upper canines finished erupting at about 34 to 41 months. Based on these developmental age calculations, S. fatalis individuals less than 4 to 7 months of age were not typically preserved at Rancho La Brea. On the whole, S. fatalis appears to have had delayed dental development compared to dental development in similar-sized extant felids. This technique for absolute ontogenetic age determination can be replicated in other ancient species, including non-saber-toothed taxa, as long as the timing of growth initiation and growth rate can be determined for a specific feature, such as a tooth, and that growth period overlaps with the development of the other features under investigation. PMID:26132165

  11. Fluorescence lifetime measurements of boronate derivatives to determine glucose concentration

    SciTech Connect

    Gable, J H

    2000-06-01

    )-anthracene (MAMA), and N-benzyl-N-methyl-N-methyl anthracene (AB-B). Fluorescence lifetime measurements confirmed the two species of AB, with and without PET. Fluorescence lifetimes were approximately 11 nsec without PET and 3 nsec with PET. The degree of the interaction between the N and the B atoms was also determined by fluorescence lifetime measurements. Electron transfer rates of AB were measured to be on the order of 10{sup 8} sec{sup -1}. Analysis of AB as a glucose sensor shows it has the potential for measuring glucose concentrations in solution with less than 5% error. Two novel glucose sensing molecules, Chloro-oxazone boronate (COB) and Napthyl-imide boronate (NIB), were synthesized. Both molecules have a N{yields}B dative bond similar to AB, but with longer wavelength fluorophores. COB and NIB were found to be unacceptable for use as glucose sensor molecules due to the small changes in average fluorescence lifetime.

  12. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  13. Determination of the absolute configuration of chaetoviridins and other bioactive azaphilones from the endophytic fungus Chaetomium globosum.

    PubMed

    Youn, Ui Joung; Sripisut, Tawanun; Park, Eun-Jung; Kondratyuk, Tamara P; Fatima, Nighat; Simmons, Charles J; Wall, Marisa M; Sun, Dianqing; Pezzuto, John M; Chang, Leng Chee

    2015-11-01

    Chemical investigation of an endophytic fungus Chaetomium globosum isolated from leaves of Wikstroemia uva-ursi led to the isolation of two new azaphilones, chaetoviridins J and K (1 and 3), along with five known derivatives (2 and 4-7). The structures of azaphilones were determined by NMR, X-ray diffraction, Mosher's method, and CD analysis. The isolated compounds were evaluated for their cancer chemopreventive-potential based on their abilities to inhibit tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB). Compounds 4, 5, 7, and synthetic 8 and 9 inhibit nitric oxide (NO) production with IC50 values in the range of 0.3-5.8 μM. Compounds 4, 5, and 9 also displayed (TNF-α)-induced NF-κB activity with IC50 values in the range of 0.9-5.1 μM. PMID:26343828

  14. The determination of absolute intensity of 234mPa's 1001 keV gamma emission using Monte Carlo simulation.

    PubMed

    Begy, Robert-Csaba; Cosma, Constantin; Timar, Alida; Fulea, Dan

    2009-05-01

    The 1001 keV gamma line of (234m)Pa became important in gamma spectrometric measurements of samples with (238)U content with the advent of development of HpGe detectors of great dimension and high efficiency. In this study the emission probability of the 1001 keV (Y(gamma)) peak of (234m)Pa, was determined by gamma-ray spectrometric measurements performed on glass with Uranium content using Monte Carlo simulation code for efficiency calibration. This method of calculation was not applied for the values quoted in literature so far, at least to our knowledge. The measurements gave an average of 0.836 +/- 0.022%, a value that is in very good agreement to some of the recent results previously presented. PMID:19384056

  15. MODELING MULTI-WAVELENGTH STELLAR ASTROMETRY. III. DETERMINATION OF THE ABSOLUTE MASSES OF EXOPLANETS AND THEIR HOST STARS

    SciTech Connect

    Coughlin, J. L.; Lopez-Morales, Mercedes

    2012-05-10

    Astrometric measurements of stellar systems are becoming significantly more precise and common, with many ground- and space-based instruments and missions approaching 1 {mu}as precision. We examine the multi-wavelength astrometric orbits of exoplanetary systems via both analytical formulae and numerical modeling. Exoplanets have a combination of reflected and thermally emitted light that causes the photocenter of the system to shift increasingly farther away from the host star with increasing wavelength. We find that, if observed at long enough wavelengths, the planet can dominate the astrometric motion of the system, and thus it is possible to directly measure the orbits of both the planet and star, and thus directly determine the physical masses of the star and planet, using multi-wavelength astrometry. In general, this technique works best for, though is certainly not limited to, systems that have large, high-mass stars and large, low-mass planets, which is a unique parameter space not covered by other exoplanet characterization techniques. Exoplanets that happen to transit their host star present unique cases where the physical radii of the planet and star can be directly determined via astrometry alone. Planetary albedos and day-night contrast ratios may also be probed via this technique due to the unique signature they impart on the observed astrometric orbits. We develop a tool to examine the prospects for near-term detection of this effect, and give examples of some exoplanets that appear to be good targets for detection in the K to N infrared observing bands, if the required precision can be achieved.

  16. Synthesis of (3S,3′S)- and meso-Stereoisomers of Alloxanthin and Determination of Absolute Configuration of Alloxanthin Isolated from Aquatic Animals

    PubMed Central

    Yamano, Yumiko; Maoka, Takashi; Wada, Akimori

    2014-01-01

    In order to determine the absolute configuration of naturally occurring alloxanthin, a HPLC analytical method for three stereoisomers 1a–c was established by using a chiral column. Two authentic samples, (3S,3′S)- and meso-stereoisomers 1b and 1c, were chemically synthesized according to the method previously developed for (3R,3′R)-alloxanthin (1a). Application of this method to various alloxanthin specimens of aquatic animals demonstrated that those isolated from shellfishes, tunicates, and crucian carp are identical with (3R,3′R)-stereoisomer 1a, and unexpectedly those from lake shrimp, catfish, biwa goby, and biwa trout are mixtures of three stereoisomers of 1a–c. PMID:24862182

  17. Determination of differential carbon dioxide concentration by conductimetric analysis

    SciTech Connect

    Baker, J.M.

    1998-09-01

    There are many applications in such disciplines as agronomy, plant physiology, and ecology where it is necessary to measure the difference in atmospheric CO{sub 2} concentration [CO{sub 2}] between two points. This is commonly done with an infrared gas analyzer, but such instruments are expensive, representing a substantial and sometimes prohibitive share of the cost of CO{sub 2}-related research. The goal of this project was to explore a simple inexpensive alternative, in which the difference in [CO{sub 2}] between two air streams is determined by bubbling the air through cells containing deionized water while measuring the ratio of their conductivities with a half-bridge measurement of electrode pairs suspended in each cell. The underlying principles are presented, and it is shown that (i) differential [CO{sub 2}] is directly proportional to the conductivity ratio minus its inverse and (ii) the coefficient of proportionality is equal to the mean [CO{sub 2}] of the two air streams. A system was designed and constructed to test these principles, and the results confirmed them. Dynamic response was characterized, and shown to be proportional to Q/V, where Q is the air flow rate and V is the water-filled volume of the cell. Differential resolution was found to be in the range of 0.4 to 0.8 {micro}mol mol{sup {minus}1}, but better resolution is theoretically possible. Differential measurement of [CO{sub 2}] by conductometry shows considerable promise, particularly considering the straightforward nature of the relationship and the relatively low cost of the required components.

  18. Determination of the Carbon Nanotube Concentration and Homogeneity in Resin Films by THz Spectroscopy and Imaging

    NASA Astrophysics Data System (ADS)

    Peters, Ole; Busch, Stefan Frederik; Fischer, Bernd Michael; Koch, Martin

    2012-12-01

    We have recorded the concentration dependent extinction coefficient and refractive index of multi-walled carbon nanotubes (MWNT) embedded in a resin fiber matrix using broadband terahertz time domain spectroscopy. The MWNT concentration levels of the samples range from 0.1 to 1 wt%. The good correlation between the measured absolute values of the transmission and the MWNT concentration reconfirms the potential of THz techniques for monitoring the loading levels. Inhomogenieties in the sample lead to strong fluctuations of the detected terahertz signal. We show that THz line scans and THz images, respectively, are therefore well suited to localize and visualize such accumulations.

  19. An attempt to determine the absolute geomagnetic field intensity in Southwestern Iceland during the Gauss-Matuyama reversal

    NASA Astrophysics Data System (ADS)

    Goguitchaichvili, Avto; Prévot, Michel; Thompson, John; Roberts, Neil

    1999-08-01

    We have measured the variation in the intensity of the geomagnetic field during the Gauss-Matuyama (N4-R3) polarity reversal by application of the Thelliers' method to specimens of lava flows from Hvalfjördur district in Western Iceland (Reynivallahals Mts.). Eleven lava flows all show very similar directions corresponding to an equatorial VGP (Plat=2.9°N, Plong=81.9°E, A95=4.2, K=119). Twenty-nine specimens from nine of the flows were pre-selected for palaeointensity determination on the basis that specimens from the same drill cores showed a single component of magnetisation upon thermal or AF demagnetisation, and possessed low magnetic viscosity and reversible susceptibility curves upon heating at 600-650°C. Observation that the directional data obtained in the course of the palaeointensity experiments occasionally showed substantial non-linearity indicates that a significant chemical remanent magnetization (CRM) can be acquired in the direction of the laboratory field during heating at T. For each double heating step we calculated the ratio of CRM( T) to the magnitude of the natural remanent magnetization (NRM( T)) in the direction of characteristic remanence (obtained independently from another specimen from the same core). When this ratio exceeded 15%, the paleointensity data was rejected. In addition, specimens for which the quality factor was less than 5 were rejected. Twelve reliable palaeointensity values were obtained from specimens representing five lava flows. The results confirm that the palaeointensity was substantially reduced during the N4-R3 reversal. The range of mean palaeointensity values obtained for the five flows is 8.8 to 20.5 and the overall mean is 14.8±4.6 μT. This corresponds to an equivalent VDM of 3.81±1.19 (10 22 A m 2). A comparison of all Thellier palaeointensity data from the R3 magnetozone in the Rayinivallahals Mts. area reveals a progressive although irregular increase in the palaeointensity between the Gauss

  20. Determination of methyl radical concentrations in a methane/air flame by infrared cavity ringdown laser absorption spectroscopy

    SciTech Connect

    Scherer, J.J.; Aniolek, K.W.; Cernansky, N.P.; Rakestraw, D.J.

    1997-10-01

    Infrared cavity ringdown laser absorption spectroscopy (IR-CRLAS) is employed to determine absolute methyl radical concentrations in a 37.5 Torr laminar methane/air flame. IR-CRLAS rovibrational absorption spectra of the {nu}{sub 3} fundamental band system near 3200thinspcm{sup {minus}1} are combined with N{sub 2}-CARS temperature measurements to obtain methyl radical concentrations as a function of height above the burner surface. These data are compared with flame chemistry simulations under both stoichiometric and rich flame conditions. Issues regarding the applicability of IR-CRLAS for combustion studies are discussed, including the uncertainties present for the specific case of methyl radical. These IR-CRLAS measurements indicate the ability to monitor reactants, intermediates, and products within a narrow spectral window, and, to our knowledge, constitute the first infrared detection of a polyatomic radical in a flame. {copyright} {ital 1997 American Institute of Physics.}

  1. Determination of Solid Particle Concentration at coal Transshipment site

    NASA Astrophysics Data System (ADS)

    Siliņš, K.; Žandeckis, A.; Valtere, S.

    2009-01-01

    Coal handling and grinding processes are associated with significant particulate matter emissions into the atmosphere. This problem is particularly urgent when a coal-processing company is located in or nearby a densely populated city. To quantitatively evaluate concentrations generated into the atmosphere according to the standardized methodology, it is necessary to make extensive measurements using an automatic real-time, infrared dust and aerosol monitor. Before the experiments, the impact of particulate matter on human health and the environment was explored, six solid particle concentration detection methods and best available techniques for particulate matter emission prevention was described. During this study field measurements were carried out at on the territory of a coal transshipment company. Using the solid particle concentration detection system Dust Detective kit, concentration monitoring of total particulate matter (TSP), PM10 and PM2.5 was carried out. The equipment was located 6 m above ground and 120 m away from the emission source - coal crushing and handling site. TSP monitoring was carried out during four diurnal, PM10 - during 17 diunral and PM2.5 - during 12 days. After comparison of results with concentration values set in normative documents of Latvia and EU, it was found out that average 17 diurnal day concentration values of PM10 exceeded normative values for nine times. PM2.5 daily average concentrations of 12 days exceeded for four times exceeded the value of 25 μg/m3, which is mentioned in Directive 2008/50/EC of EU. After analysis of wind behaviour impact on the concentration values it is now understood that if wind comes from the dust emission source to the measurement system, the increase in wind speed increases particle concentration as all particles in the air and those raised from coal piles are driven towards the equipment. If wind comes from the opposite direction, the decrease of wind velocity results in an increase of

  2. The role of endophyte in determining swainsonine concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Locoweeds contain the toxic indolizidine alkaloid swainsonine, which is produced by the endophytic fungi Undifilum species. Previously we reported that swainsonine concentrations differ between populations of Oxytropis sericea. We hypothesized that the genotype of the plant, endophyte, or an inter...

  3. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  4. Investigations concerning the determination of NADH concentrations using optical biopsy

    NASA Astrophysics Data System (ADS)

    Beuthan, Juergen; Bocher, Thomas; Minet, Olaf; Roggan, Andre; Schmitt, Isabella; Weber, A.; Mueller, Gerhard J.

    1994-05-01

    The intrinsic NADH autofluorescence intensity of biological tissue depends on the local, cellular concentration of this coenzyme. It plays a dominant role in the Krebs-Cycle and therefore serves as indicator for the vitality of the observed cells. Due to individually and locally varying boundary conditions and optical tissue properties, which are scattering coefficients, absorption coefficients and g-factors the fluorescence signal needs to be rescaled. One possible rescaling method is the theoretical derived Photon Migration Theory. Our new rescaling method is partly based on measurements and partly theoretical derived. By using the 4 information channels: LIF time-resolved signal, biochemical concentration measurements, Monte Carlo simulations with optical parameters and microscopic investigations we demonstrate that simultaneous detection of the fluorescence and the backscattering signal can easily and accurately provide rescaled, quantitative values for the NADH concentrations.

  5. Concentration determination of oxygen nanobubbles in electrolyzed water.

    PubMed

    Kikuchi, Kenji; Ioka, Aoi; Oku, Takeo; Tanaka, Yoshinori; Saihara, Yasuhiro; Ogumi, Zempachi

    2009-01-15

    Water electrolysis is well known to produce solutions supersaturated with oxygen. The oxygen in electrolyzed solutions was analyzed with a dissolved oxygen meter and the Winkler method of chemical analysis. The concentration of oxygen measured with the dissolved oxygen meter agreed with that obtained using the Winkler method. However, measurements using a 10-fold dilution method showed a larger concentration of dissolved oxygen compared to the above methods. We developed a modified Winkler method to measure total oxygen concentration more accurately, which agreed with the results obtained from the 10-fold dilution experiment. The difference in measurements is due to the existence of oxygen nanobubbles, as confirmed by the observation of dynamic light scattering using a laser. Further analysis of the oxygen nanobubbles demonstrated that the stability of the nanobubbles was sufficient for chemical reaction and solvation to bulk solution. PMID:18977493

  6. Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves of the Contact Binary -I. V417 Aquilae

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Kim, Chun-Hwey; Lee, Chung-Uk; Oh, Kyu-Dong

    2004-06-01

    New photometric and spectroscopic solutions of W-type overcontact binary V417 Aql were obtained by solving the UBV light curves of Samec et al. (1997) and radial-velocity ones of Lu & Rucinski (1999) with the 2003 version of the Wilson-Devinney binary code. In the light curve synthesis the light of a third-body, which Qian (2003) proposed, was considered and obtained about 2.7%, 2.2%, and 0.4% for U, B, and V bandpasses, respectively. The model with third-light is better fitted to eclipse parts than that with no third-light. Absolute dimensions of V417 Aql are determined from our solution as M1=0.53 M⊙, M2=1.45 M⊙, R1=0.84 R⊙ and R2=1.31 M⊙, and the distance to it is deduced as about 216pc. Our distance is well consistent with that (204pc) derived from Rucinski & Duerbeck's (1997) relation, MV=MV(log P, B-V), but is more distant than that (131±40pc) determined by the Hipparcos trigonometric parallax. The difference may result from the relatively large error of Hipparcos parallax for V417 Aql.

  7. Influence of GPS/GLONASS differential code biases on the determination accuracy of the absolute total electron content in the ionosphere

    NASA Astrophysics Data System (ADS)

    Yasyukevich, Yu. V.; Mylnikova, A. A.; Kunitsyn, V. E.; Padokhin, A. M.

    2015-11-01

    Systematic error arises when the total electron content (TEC) is estimated with the simultaneous use of phase and code GPS/GLONASS measurements. This is related to the different signal propagation times at L1 and L2 frequencies in the radio frequency path of the transmitting and receiving equipment, the so-called differential code biases. A differential code bias of 1 ns results in an error of ~2.9 TECU when TEC is determined. Differential code bias variations on a long time interval, which were obtained at the CODE laboratory, were analyzed. It has been found that the systematic variation in these biases and considerable seasonal variations apparently caused by the environmental state (temperature and humidity), which sometimes reach 20 TECU (in TEC units), are observed for several stations. The algorithm for determining differential code biases at an individual station and the results of correction for absolute slant TEC are also presented. Presented results show algorithm effectiveness for various geographical regions and solar activity.

  8. MODELING MULTI-WAVELENGTH STELLAR ASTROMETRY. II. DETERMINING ABSOLUTE INCLINATIONS, GRAVITY-DARKENING COEFFICIENTS, AND SPOT PARAMETERS OF SINGLE STARS WITH SIM LITE

    SciTech Connect

    Coughlin, Jeffrey L.; Harrison, Thomas E.; Gelino, Dawn M.

    2010-11-10

    We present a novel technique to determine the absolute inclination of single stars using multi-wavelength submilliarcsecond astrometry. The technique exploits the effect of gravity darkening, which causes a wavelength-dependent astrometric displacement parallel to a star's projected rotation axis. We find that this effect is clearly detectable using SIM Lite for various giant stars and rapid rotators, and present detailed models for multiple systems using the REFLUX code. We also explore the multi-wavelength astrometric reflex motion induced by spots on single stars. We find that it should be possible to determine spot size, relative temperature, and some positional information for both giant and nearby main-sequence stars utilizing multi-wavelength SIM Lite data. These data will be extremely useful in stellar and exoplanet astrophysics, as well as supporting the primary SIM Lite mission through proper multi-wavelength calibration of the giant star astrometric reference frame, and reduction of noise introduced by starspots when searching for extrasolar planets.

  9. Laser Light: Using Laser Refractometry to Determine Concentration.

    ERIC Educational Resources Information Center

    Gauger, Robert

    1995-01-01

    Laser refractometry is a science-technology-based activity that requires students to manipulate a variety of equipment, tools, materials, and critical-thinking skills. Students use a laser to measure the percent of glucose in a solution by calibrating the system, taking measurements, and computing the concentration. (MKR)

  10. Osmolyte concentration: A new method for determining malt quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The primary ASBC, IoB, and EBC methods for measuring malt quality, although frequently modified, have basically remained the same for decades and in some cases centuries. Recent studies have found that malt osmolyte concentrations (OC) are excellent predictors of malt extract (ME), diastatic power ...

  11. Electronic Absolute Cartesian Autocollimator

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2006-01-01

    An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the

  12. Ion exchange determines iodine-131 concentration in aqueous samples

    NASA Technical Reports Server (NTRS)

    Fairman, W. D.; Sedlet, J.

    1967-01-01

    Inorganic radioiodide in aqueous media is analyzed by separating the radioactive iodine-131 as the iodide ion on a silver chloride column. The activity in the final precipitate may be determined by beta or gamma counting.

  13. Direct gravimetric determination of aerosol mass concentration in central antarctica.

    PubMed

    Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

    2011-01-01

    In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station. PMID:21141836

  14. Determination of optimal glycerol concentration for optical tissue clearing

    NASA Astrophysics Data System (ADS)

    Youn, Eungjun; Son, Taeyoon; Kim, Han-Sung; Jung, Byungjo

    2012-02-01

    The laser scattering in tissue is significant in diagnostic and therapeutic purposes of laser. Many studies have been conducted to minimize laser scattering in tissue and therefore, to maximize the clinical efficacy by enhancing photon density. Optical clearing agents (OCAs) have been employed for optical tissue clearing (OTC). This study was aimed to investigate the optimal concentration of an OCA, glycerol, in topical application,, so that it can be utilized for clinical diagnosis and therapy in dermatology. Glycerol was topically applied to avoid possible edema caused by dermal injection. The effect of OTC was quantitatively evaluated as a function of the concentration of glycerol with various methods. Optical methods such as optical coherence tomography (OCT) and an integrating sphere were used to assess the enhancement of light penetration depth and refractive index matching. In addition, a non-optical method, ultrasound scanner, was utilized to evaluate quantitatively collagen dissociation. The results revealed that 70 % glycerol was the optimal concentration of OTC for topical application. This study may provide a guideline regarding to the use of glycerol for optimal diagnostic and therapeutic effects in dermatology.

  15. Determination of flue gas alkali concentrations in fluidized-bed coal combustion by excimer-laser-induced fragmentation fluorescence

    SciTech Connect

    Hartinger, K.T.; Monkhouse, P.B.; Wolfrum, J.; Baumann, H.; Bonn, B.

    1994-12-31

    Gas-phase sodium concentrations were measured for the first time in situ in the flue gas of a fluidized-bed reactor by the excimer-laser-induced fragmentation fluorescence (ELIF) technique. This method involves using ArF-excimer laser light at 193 nm to simultaneously photodissociate the alkali compounds of interest and excite electronically the alkali atoms formed. The resulting fluorescence from Na (3{sup 2}P) atoms can he readily detected at 589 nm. Measured signals were converted to absolute concentrations using a calibration system that monitors alkali compounds under known conditions of temperature, pressure, and composition and rising the same optical setup as at the reactor. Several different coals were investigated under a specific set of reactor conditions at total pressures close to 1 bar. Sodium concentrations ranging from the sub-ppb region to 20 ppb were obtained, and a detection limit for sodium of 0.1 ppb under the present conditions was estimated. Over the course of the reactor program, contrasting concentration histories were observed for the two lignites and the hard coal investigated. In particular, significantly higher sodium concentrations were found for the hard coal, consistent with both the higher chlorine and sodium contents determined in the corresponding coal analysis.

  16. Genome-Wide Association Study of Absolute QRS Voltage Identifies Common Variants of TBX3 as Genetic Determinants of Left Ventricular Mass in a Healthy Japanese Population

    PubMed Central

    Sano, Motoaki; Kamitsuji, Shigeo; Kamatani, Naoyuki; Tabara, Yasuharu; Kawaguchi, Takahisa; Matsuda, Fumihiko; Yamagishi, Hiroyuki; Fukuda, Keiichi

    2016-01-01

    Left ventricular hypertrophy (LVH) represents a common final pathway leading to heart failure. We have searched for genetic determinants of left ventricular (LV) mass using values for absolute electrocardiographic QRS voltage in a healthy Japanese population. After adjusting for covariates, the corrected S and R wave voltages in leads V1 and V5 from 2,994 healthy volunteers in the Japan Pharmacogenomics Data Science Consortium (JPDSC) database were subjected to a genome-wide association study. Potential associations were validated by an in silico replication study using an independent Japanese population obtained from the Nagahama Prospective Genome Cohort for Comprehensive Human Bioscience. We identified a novel association between the lead V5, R wave voltage in Japanese individuals and SNP rs7301743[G], which maps near the gene encoding T-box transcription factor Tbx3. Meta-analysis of two independent Japanese datasets demonstrated a marginally significant association of SNP rs7301743 in TBX3|MED13L with a 0.071 mV (95% CI, 0.038–0.11 mV) shorter R wave amplitude in the V5 lead per minor allele copy (P = 7.635 x 10−8). The transcriptional repressor, TBX3, is proposed to suppress the development of working ventricular myocardium. Our findings suggest that genetic variation of Tbx3 is associated with LV mass in a healthy Japanese population. PMID:27195777

  17. Absolute number densities of helium metastable atoms determined by atomic absorption spectroscopy in helium plasma-based discharges used as ambient desorption/ionization sources for mass spectrometry

    NASA Astrophysics Data System (ADS)

    Reininger, Charlotte; Woodfield, Kellie; Keelor, Joel D.; Kaylor, Adam; Fernández, Facundo M.; Farnsworth, Paul B.

    2014-10-01

    The absolute number densities of helium atoms in the 2s 3S1 metastable state were determined in four plasma-based ambient desorption/ionization sources by atomic absorption spectroscopy. The plasmas included a high-frequency dielectric barrier discharge (HF-DBD), a low temperature plasma (LTP), and two atmospheric-pressure glow discharges, one with AC excitation and the other with DC excitation. Peak densities in the luminous plumes downstream from the discharge capillaries of the HF-DBD and the LTP were 1.39 × 1012 cm- 3 and 0.011 × 1012 cm- 3, respectively. Neither glow discharge produced a visible afterglow, and no metastable atoms were detected downstream from the capillary exits. However, densities of 0.58 × 1012 cm- 3 and 0.97 × 1012 cm- 3 were measured in the interelectrode regions of the AC and DC glow discharges, respectively. Time-resolved measurements of metastable atom densities revealed significant random variations in the timing of pulsed absorption signals with respect to the voltage waveforms applied to the discharges.

  18. Energy yield determination of concentrator solar cells using laboratory measurements

    NASA Astrophysics Data System (ADS)

    Geisz, John F.; García, Iván; McMahon, William E.; Steiner, Myles A.; Ochoa, Mario; France, Ryan M.; Habte, Aron; Friedman, Daniel J.

    2015-09-01

    The annual energy conversion efficiency is calculated for a four junction inverted metamorphic solar cell that has been completely characterized in the laboratory at room temperature using measurements fit to a comprehensive optoelectronic model of the multijunction solar cells. A simple model of the temperature dependence is used predict the performance of the solar cell under varying temperature and spectra characteristic of Golden, CO for an entire year. The annual energy conversion efficiency is calculated by integrating the predicted cell performance over the entire year. The effects of geometric concentration, CPV system thermal characteristics, and luminescent coupling are highlighted.

  19. Use of passive sampling devices to determine soil contaminant concentrations

    SciTech Connect

    Johnson, K.A. |; Hooper, M.J.; Weisskopf, C.P.

    1996-12-31

    The effective remediation of contaminated sites requires accurate identification of chemical distributions. A rapid sampling method using passive sampling devices (PSDs) can provide a thorough site assessment. We have been pursuing their application in terrestrial systems and have found that they increase the ease and speed of analysis, decrease solvent usage and overall cost, and minimize the transport of contaminated soils. Time and cost savings allow a higher sampling frequency than is generally the case using traditional methods. PSDs have been used in the field in soils of varying physical properties and have been successful in estimating soil concentrations ranging from 1 {mu}g/kg (parts per billion) to greater than 200 mg/kg (parts per million). They were also helpful in identifying hot spots within the sites. Passive sampling devices show extreme promise as an analytical tool to rapidly characterize contaminant distributions in soil. There are substantial time and cost savings in laboratory personnel and supplies. By selectively excluding common interferences that require sample cleanup, PSDs can be retrieved from the field and processed rapidly (one technician can process approximately 90 PSDs in an 8-h work day). The results of our studies indicate that PSDs can be used to accurately estimate soil contaminant concentrations and provide lower detection limits. Further, time and cost savings will allow a more thorough and detailed characterization of contaminant distributions. 13 refs., 4 figs., 2 tabs.

  20. 40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or...

  1. 40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or...

  2. 40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or...

  3. 40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or...

  4. 40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or...

  5. Factors affecting atrazine concentration and quantitative determination in chlorinated water.

    PubMed

    Wulfeck-Kleier, Karen A; Ybarra, Michael D; Speth, Thomas F; Magnuson, Matthew L

    2010-01-29

    Although the herbicide atrazine has been reported to not react measurably with free chlorine during drinking water treatment, this work demonstrates that at contact times consistent with drinking water distribution system residence times, a transformation of atrazine can be observed. Some transformation products detected through the use of high performance liquid chromatography-electrospray mass spectrometry are consistent with the formation of N-chloro atrazine. The effects of applied chlorine, pH, and reaction time on the transformation reaction were studied to help understand the practical implications of the transformation on the accurate determination of atrazine in drinking waters. The errors in the determination of atrazine are a function of the type of dechlorinating agent applied during sample preparation and the analytical instrumentation utilized. When a reductive dechlorinating agent, such as sodium sulfite or ascorbic acid is used, the quantification of the atrazine can be inaccurate, ranging from 2-fold at pH 7.5 to 30-fold at pH 6.0. The results suggest HPLC/UV and ammonium chloride quenching may be best for accurate quantification. Hence, the results also appear to have implications for both compliance monitoring and health effects studies that utilize gas chromatography analysis with sodium sulfite or ascorbic acid as the quenching agent. PMID:20022012

  6. On determination of low oxygen concentrations with Winkler technique

    NASA Astrophysics Data System (ADS)

    Yakushev, E. V.; Vinogradova, E. L.; Dubinin, A. V.; Kostyleva, A. V.; Men'shikova, N. M.; Pakhomova, S. V.

    2012-02-01

    The accuracy and detection limit of the oxygen technique is an actual problem in studying the processes that occur in the redox zone. The formal accuracy of the Winkler technique is 1 μM (0.02 mL L-1) and its detection limit is about 3.0 μM (0.06 mL L-1). These values are significantly higher than the similar characteristics (in molar concentrations) for such parameters as the hydrogen sulphide, nitrates, manganese, and others. In this work, we describe some recommendations for increasing the accuracy of the Winkler technique. The results of the application of these recommendations for the suboxic zone of the Black Sea are presented. During the 100th cruise of the R/V Professor Shtokman, argon-filled balloons were attached to the upper valves of Niskin bottles during the sampling, which allowed protecting the samples from contamination with atmospheric oxygen. The titration was performed with an automatic Metrohm Titrino burette with potentiometric end point detection. That allowed us to significantly increase the accuracy and decrease the detection limit compared with the visual techniques. The oxidized forms of metals present in the sea water (Mn(IV), Mn(III); Fe(III)) were measured, which allowed us to correct the Winkler technique calculations for the oxidizers. The studies performed during the 100th cruise of the R/V Professor Shtokman confirmed the absence of a layer of the coexistence of oxygen and hydrogen sulphide.

  7. Intraspecific genotypic variability determines concentrations of key truffle volatiles.

    PubMed

    Splivallo, Richard; Valdez, Nayuf; Kirchhoff, Nina; Ona, Marta Castiella; Schmidt, Jean-Pierre; Feussner, Ivo; Karlovsky, Petr

    2012-05-01

    • Aroma variability in truffles has been attributed to maturation (Tuber borchii), linked to environmental factors (Tuber magnatum), but the involvement of genetic factors has been ignored. We investigated aroma variability in Tuber uncinatum, a species with wide distribution. Our aim was to assess aroma variability at different spatial scales (i.e. trees, countries) and to quantify how aroma was affected by genotype, fruiting body maturity, and geographical origin. • A volatile fingerprinting method was used to analyze the aroma of 223 T. uncinatum fruiting bodies from seven European countries. Maturity was estimated from spore melanization. Genotypic fingerprinting was performed by amplified fragment length polymorphism (AFLP). • Discriminant analysis revealed that, regardless of the geographical origin of the truffles, most of the aroma variability was caused by eight-carbon-containing volatiles (C8-VOCs). In an orchard of T. uncinatum, truffles producing different concentrations of C8-VOCs clustered around distinct host trees. This clustering was not associated with maturity, but was associated with fungal genotype. • These results indicate that the variation in C8-VOCs in truffles is most likely under genetic control. They exemplify that understanding the factors behind aroma variability requires a holistic approach. Furthermore, they also raise new questions regarding the ecological role of 1-octen-3-ol in truffles. PMID:22394027

  8. Intraspecific genotypic variability determines concentrations of key truffle volatiles

    PubMed Central

    Splivallo, Richard; Valdez, Nayuf; Kirchhoff, Nina; Ona, Marta Castiella; Schmidt, Jean-Pierre; Feussner, Ivo; Karlovsky, Petr

    2012-01-01

    Aroma variability in truffles has been attributed to maturation (Tuber borchii), linked to environmental factors (Tuber magnatum), but the involvement of genetic factors has been ignored. We investigated aroma variability in Tuber uncinatum, a species with wide distribution. Our aim was to assess aroma variability at different spatial scales (i.e. trees, countries) and to quantify how aroma was affected by genotype, fruiting body maturity, and geographical origin. A volatile fingerprinting method was used to analyze the aroma of 223 T. uncinatum fruiting bodies from seven European countries. Maturity was estimated from spore melanization. Genotypic fingerprinting was performed by amplified fragment length polymorphism (AFLP). Discriminant analysis revealed that, regardless of the geographical origin of the truffles, most of the aroma variability was caused by eight-carbon-containing volatiles (C8-VOCs). In an orchard of T. uncinatum, truffles producing different concentrations of C8-VOCs clustered around distinct host trees. This clustering was not associated with maturity, but was associated with fungal genotype. These results indicate that the variation in C8-VOCs in truffles is most likely under genetic control. They exemplify that understanding the factors behind aroma variability requires a holistic approach. Furthermore, they also raise new questions regarding the ecological role of 1-octen-3-ol in truffles. PMID:22394027

  9. Genetic Determinants of Circulating Sphingolipid Concentrations in European Populations

    PubMed Central

    Pramstaller, Peter P.; Rudan, Igor; Franklin, Christopher S.; Liebisch, Gerhard; Erdmann, Jeanette; Jonasson, Inger; Zorkoltseva, Irina V.; Pattaro, Cristian; Hayward, Caroline; Isaacs, Aaron; Hengstenberg, Christian; Campbell, Susan; Gnewuch, Carsten; Janssens, A. CecileJ.W.; Kirichenko, Anatoly V.; König, Inke R.; Marroni, Fabio; Polasek, Ozren; Demirkan, Ayse; Kolcic, Ivana; Schwienbacher, Christine; Igl, Wilmar; Biloglav, Zrinka; Witteman, Jacqueline C. M.; Pichler, Irene; Zaboli, Ghazal; Axenovich, Tatiana I.; Peters, Annette; Schreiber, Stefan; Wichmann, H.-Erich; Schunkert, Heribert; Hastie, Nick; Oostra, Ben A.; Wild, Sarah H.; Meitinger, Thomas; Gyllensten, Ulf; van Duijn, Cornelia M.; Wilson, James F.; Wright, Alan; Schmitz, Gerd; Campbell, Harry

    2009-01-01

    Sphingolipids have essential roles as structural components of cell membranes and in cell signalling, and disruption of their metabolism causes several diseases, with diverse neurological, psychiatric, and metabolic consequences. Increasingly, variants within a few of the genes that encode enzymes involved in sphingolipid metabolism are being associated with complex disease phenotypes. Direct experimental evidence supports a role of specific sphingolipid species in several common complex chronic disease processes including atherosclerotic plaque formation, myocardial infarction (MI), cardiomyopathy, pancreatic β-cell failure, insulin resistance, and type 2 diabetes mellitus. Therefore, sphingolipids represent novel and important intermediate phenotypes for genetic analysis, yet little is known about the major genetic variants that influence their circulating levels in the general population. We performed a genome-wide association study (GWAS) between 318,237 single-nucleotide polymorphisms (SNPs) and levels of circulating sphingomyelin (SM), dihydrosphingomyelin (Dih-SM), ceramide (Cer), and glucosylceramide (GluCer) single lipid species (33 traits); and 43 matched metabolite ratios measured in 4,400 subjects from five diverse European populations. Associated variants (32) in five genomic regions were identified with genome-wide significant corrected p-values ranging down to 9.08×10−66. The strongest associations were observed in or near 7 genes functionally involved in ceramide biosynthesis and trafficking: SPTLC3, LASS4, SGPP1, ATP10D, and FADS1–3. Variants in 3 loci (ATP10D, FADS3, and SPTLC3) associate with MI in a series of three German MI studies. An additional 70 variants across 23 candidate genes involved in sphingolipid-metabolizing pathways also demonstrate association (p = 10−4 or less). Circulating concentrations of several key components in sphingolipid metabolism are thus under strong genetic control, and variants in these loci can be

  10. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  11. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  12. Absolute Determination for the Sodium-22(p,gamma)Magnesium-23 Reaction Rate: Consequences for Nucleosynthesis of Sodium-22 in Novae

    NASA Astrophysics Data System (ADS)

    Sallaska, Anne L.

    2010-11-01

    Hydrodynamic simulations of classical novae on ONe white dwarfs predict substantial production of 22Na. Observation of 22Na decay should be correlated with the corresponding nova because the half life of 22Na is only 2.6 years. The 1275-keV gamma ray from the beta decay of 22Na is, therefore, an excellent diagnostic for the nova phenomenon and a long-sought target of gamma-ray telescopes. Nova simulations determine the maximum 22Na-detection distance to be < 1 kpc for the INTEGRAL spectrometer SPI, consistent with its non-observation to date. However, model estimates are strongly dependent on the thermonuclear rate of the 22Na(p, gamma)23Mg reaction, which is the main destruction mechanism of 22Na in novae. The 22Na(p,gamma)23Mg rate is expected to be dominated by narrow, isolated resonances with Ep < 300 key. The currently employed rate is based on a single set of absolute resonance-strength measurements with Ep ≥ 290 keV, and one relative measurement of resonances with Ep ≥ 214 keV. Recently, a new level has been found in 23Mg which would correspond to a resonance at Ep = 198 keV that might dominate the reaction rate at nova temperatures. We have measured the 22Na(p, gamma) 23Mg resonance strengths directly and absolutely, in addition to resonance energies and branches. Proton beams were produced at the University of Washington and delivered to a specially designed beam line that included rastering and cold vacuum protection of the 22Na-implanted targets (fabricated at TRIUMF-ISAC). Two high-purity germanium detectors were employed and surrounded by anticoincidence shields to reduce cosmic backgrounds. Measurements were made on known 22Na+p resonances, which we observed at laboratory energies Ep = 213, 288, 454, 610 keV and on proposed resonances at Ep = 198, 209, and 232 key. The proposed resonances were not observed, and the upper limit placed on the 198-keV resonance strength indicates that the resonance at Ep = 213 keV still dominates the reaction rate

  13. Absolute determination of single-stranded and self-complementary adeno-associated viral vector genome titers by droplet digital PCR.

    PubMed

    Lock, Martin; Alvira, Mauricio R; Chen, Shu-Jen; Wilson, James M

    2014-04-01

    Accurate titration of adeno-associated viral (AAV) vector genome copies is critical for ensuring correct and reproducible dosing in both preclinical and clinical settings. Quantitative PCR (qPCR) is the current method of choice for titrating AAV genomes because of the simplicity, accuracy, and robustness of the assay. However, issues with qPCR-based determination of self-complementary AAV vector genome titers, due to primer-probe exclusion through genome self-annealing or through packaging of prematurely terminated defective interfering (DI) genomes, have been reported. Alternative qPCR, gel-based, or Southern blotting titering methods have been designed to overcome these issues but may represent a backward step from standard qPCR methods in terms of simplicity, robustness, and precision. Droplet digital PCR (ddPCR) is a new PCR technique that directly quantifies DNA copies with an unparalleled degree of precision and without the need for a standard curve or for a high degree of amplification efficiency; all properties that lend themselves to the accurate quantification of both single-stranded and self-complementary AAV genomes. Here we compare a ddPCR-based AAV genome titer assay with a standard and an optimized qPCR assay for the titration of both single-stranded and self-complementary AAV genomes. We demonstrate absolute quantification of single-stranded AAV vector genomes by ddPCR with up to 4-fold increases in titer over a standard qPCR titration but with equivalent readout to an optimized qPCR assay. In the case of self-complementary vectors, ddPCR titers were on average 5-, 1.9-, and 2.3-fold higher than those determined by standard qPCR, optimized qPCR, and agarose gel assays, respectively. Droplet digital PCR-based genome titering was superior to qPCR in terms of both intra- and interassay precision and is more resistant to PCR inhibitors, a desirable feature for in-process monitoring of early-stage vector production and for vector genome biodistribution

  14. Process for determining the concentration of benzodiazepines in a body fluid

    SciTech Connect

    Braestrup, C.; Squires, R.F.

    1981-07-28

    A process for determining the concentration of benzodiazepines in a body liquid comprising the steps of contacting freeze-dried brain tissue with tritium labelled flunitrazepam to bond labelled flunitrazepam to receptor sites of the brain tissue, determining the concentration of labelled flunitrazepam of the brain tissue, incubating the brain tissue containing labelled flunitrazepam with a sample of body liquid containing benzodiazepine, the concentration of which is to be determined, to induce displacement of labelled flunitrazepam from said brain tissue, determining the concentration of labelled flunitrazepam bonded to the brain tissue after establishing equilibrium conditions and determining the concentration of benzodiazepine in the body liquid based on the change of concentration of labelled flunitrazepam induced by benzodiazepine contained in the sample.

  15. 40 CFR 92.130 - Determination of steady-state concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... concentrations. 92.130 Section 92.130 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR....130 Determination of steady-state concentrations. (a)(1) For HC and NOX emissions, a steady-state concentration measurement, measured after 300 seconds (or 840 seconds for notch 8) of testing shall be...

  16. 40 CFR 92.130 - Determination of steady-state concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... concentrations. 92.130 Section 92.130 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR....130 Determination of steady-state concentrations. (a)(1) For HC and NOX emissions, a steady-state concentration measurement, measured after 300 seconds (or 840 seconds for notch 8) of testing shall be...

  17. 40 CFR 92.130 - Determination of steady-state concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... concentrations. 92.130 Section 92.130 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR....130 Determination of steady-state concentrations. (a)(1) For HC and NOX emissions, a steady-state concentration measurement, measured after 300 seconds (or 840 seconds for notch 8) of testing shall be...

  18. 40 CFR 92.130 - Determination of steady-state concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... concentrations. 92.130 Section 92.130 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR....130 Determination of steady-state concentrations. (a)(1) For HC and NOX emissions, a steady-state concentration measurement, measured after 300 seconds (or 840 seconds for notch 8) of testing shall be...

  19. 40 CFR 92.130 - Determination of steady-state concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... concentrations. 92.130 Section 92.130 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR....130 Determination of steady-state concentrations. (a)(1) For HC and NOX emissions, a steady-state concentration measurement, measured after 300 seconds (or 840 seconds for notch 8) of testing shall be...

  20. Vapor-phase concentrations of PAHs and their derivatives determined in a large city: correlations with their atmospheric aerosol concentrations.

    PubMed

    Barrado, Ana Isabel; García, Susana; Sevillano, Marisa Luisa; Rodríguez, Jose Antonio; Barrado, Enrique

    2013-11-01

    Thirteen PAHs, five nitro-PAHs and two hydroxy-PAHs were determined in 55 vapor-phase samples collected in a suburban area of a large city (Madrid, Spain), from January 2008 to February 2009. The data obtained revealed correlations between the concentrations of these compounds and a series of meteorological factors (e.g., temperature, atmospheric pressure) and physical-chemical factors (e.g., nitrogen and sulfur oxides). As a consequence, seasonal trends were observed in the atmospheric pollutants. A "mean sample" for the 14-month period would contain a total PAH concentration of 13835±1625 pg m(-3) and 122±17 pg m(-3) of nitro-PAHs. When the data were stratified by season, it emerged that a representative sample of the coldest months would contain 18900±2140 pg m(-3) of PAHs and 150±97 pg m(-3) of nitro-PAHs, while in an average sample collected in the warmest months, these values drop to 9293±1178 pg m(-3) for the PAHs and to 97±13 pg m(-3) for the nitro-PAHs. Total vapor phase concentrations of PAHs were one order of magnitude higher than concentrations detected in atmospheric aerosol samples collected on the same dates. Total nitro-PAH concentrations were comparable to their aerosol concentrations whereas vapor phase OH-PAHs were below their limits of the detection, indicating these were trapped in airborne particles. PMID:23816454

  1. Transient absolute robustness in stochastic biochemical networks.

    PubMed

    Enciso, German A

    2016-08-01

    Absolute robustness allows biochemical networks to sustain a consistent steady-state output in the face of protein concentration variability from cell to cell. This property is structural and can be determined from the topology of the network alone regardless of rate parameters. An important question regarding these systems is the effect of discrete biochemical noise in the dynamical behaviour. In this paper, a variable freezing technique is developed to show that under mild hypotheses the corresponding stochastic system has a transiently robust behaviour. Specifically, after finite time the distribution of the output approximates a Poisson distribution, centred around the deterministic mean. The approximation becomes increasingly accurate, and it holds for increasingly long finite times, as the total protein concentrations grow to infinity. In particular, the stochastic system retains a transient, absolutely robust behaviour corresponding to the deterministic case. This result contrasts with the long-term dynamics of the stochastic system, which eventually must undergo an extinction event that eliminates robustness and is completely different from the deterministic dynamics. The transiently robust behaviour may be sufficient to carry out many forms of robust signal transduction and cellular decision-making in cellular organisms. PMID:27581485

  2. Absolute neutrino mass measurements

    NASA Astrophysics Data System (ADS)

    Wolf, Joachim

    2011-10-01

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2β) searches, single β-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy. Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium β-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope (137Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R&D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2β decay and single β-decay.

  3. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  4. Diagnostic Application of Absolute Neutron Activation Analysis in Hematology

    SciTech Connect

    Zamboni, C.B.; Oliveira, L.C.; Dalaqua, L. Jr.

    2004-10-03

    The Absolute Neutron Activation Analysis (ANAA) technique was used to determine element concentrations of Cl and Na in blood of healthy group (male and female blood donators), select from Blood Banks at Sao Paulo city, to provide information which can help in diagnosis of patients. This study permitted to perform a discussion about the advantages and limitations of using this nuclear methodology in hematological examinations.

  5. TE = 32 ms vs TE = 100 ms echo‐time 1H‐magnetic resonance spectroscopy in prostate cancer: Tumor metabolite depiction and absolute concentrations in tumors and adjacent tissues

    PubMed Central

    Basharat, Meer; Morgan, Veronica A.; Parker, Chris; Dearnaley, David; deSouza, Nandita M.

    2015-01-01

    Purpose To compare the depiction of metabolite signals in short and long echo time (TE) prostate cancer spectra at 3T, and to quantify their concentrations in tumors of different stage and grade, and tissues adjacent to tumor. Materials and Methods First, single‐voxel magnetic resonance imaging (MRI) spectra were acquired from voxels consisting entirely of tumor, as defined on T 2‐weighted and diffusion‐weighted (DW)‐MRI and from a biopsy‐positive octant, at TEs of 32 msec and 100 msec in 26 prostate cancer patients. Then, in a separate cohort of 26 patients, single‐voxel TE = 32 msec MR spectroscopy (MRS) was performed over a partial‐tumor region and a matching, contralateral normal‐appearing region, defined similarly. Metabolite depiction was compared between TEs using Cramér‐Rao lower bounds (CRLB), and absolute metabolite concentrations were calculated from TE = 32 msec spectra referenced to unsuppressed water spectra. Results Citrate and spermine resonances in tumor were better depicted (had significantly lower CRLB) at TE = 32 msec, while the choline resonance was better depicted at TE = 100 msec. Citrate and spermine concentrations were significantly lower in patients of more advanced stage, significantly lower in Gleason grade 3+4 than 3+3 tumors, and significantly lower than expected from the tumor fraction in partial‐tumor voxels (by 14 mM and 4 mM, respectively, P < 0.05). Conclusion Citrate and spermine resonances are better depicted at short TE than long TE in tumors. Reduction in these concentrations is related to increasing tumor stage and grade in vivo, while reductions in the normal‐appearing tissues immediately adjacent to tumor likely reflect tumor field effects. J. Magn. Reson. Imaging 2015;42:1086–1093. PMID:26258905

  6. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  7. Determination of threshold concentrations of metals in indicator algae of coastal waters in the northwest Sea of Japan

    NASA Astrophysics Data System (ADS)

    Chernova, E. N.; Kozhenkova, S. I.

    2016-05-01

    Background concentrations of Fe, Mn, Cu, Zn, Pb, Cd, and Ni were calculated for thalli of abundant algae of Fucus, Silvetia, Sargassum, Cystoseira spp. from the northwest Sea of Japan during 1987-2008. As the upper threshold levels of metal background concentrations, the median values plus double medians of absolute deviations from the medians were used (Me + 2MAD). The lower threshold level of the background concentration equal to the physiological need for an element is the median of 15% minimum values in the sampling minus the double median of absolute deviations from the median (Me15-2MAD15). The range of Me15 ± 2MAD15 is considered the natural background range of concentrations.

  8. Determination of the concentration of a Bryonia Dioica tincture by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Milea, Irimie; Culea, E.; Iliescu, T.; Milea, Janetta

    1995-03-01

    It was established a method based on Raman spectroscopy in order to control the content and concentration of homeopathic dilutions. Dilutions of a tincture of Bryonia Dioica in ethanol were prepared and investigated by Raman spectroscopy. The Raman line at 881 cm-1 was found to depend linearly versus the concentration of Bryonia Dioica. This permits to obtain a calibration curve that may be used to determine the concentration of Bryonia Dioica in ethanol. The method may be extended to determine the concentration of various homeopathic dilutions.

  9. Sorption concentration and inductively coupled plasma determination of Mo, V, Zr, and Cr in sea water

    SciTech Connect

    Shcherbinina, N.I.; Ishmiyarova, G.P.; Myasoedova, G.V.

    1992-02-10

    Sorption on complex-forming sorbents is an expanding method for the concentration of microelements for water analysis. The adsorbed elements can be determined directly in the concentrate, in the eluate after desorption or in the residue after decomposition of the sorbent. Among the methods used to determine the elements is atomic emission spectrometry from an inductively coupled plasma (ICP). This method is often used to determine relatively easily desorbed metals. In the present work, the authors investigate the concentration of Mo, V, Zr, and Cr(VI) with the complex forming sorbent POLIORGS VII M and their subsequent determination of ICP. These hard to desorb metals are put back into solution by the rapid microwave decomposition of the sorbent/concentrate with a HNO{sub 3}/H{sub 2}O{sub 2} mixture. The developed method for the determination of Mo, V, Zr, and Cr(VI) was used to analyze sea water. 14 refs., 1 fig., 6 tabs.

  10. Synthesis and determination of the absolute configuration of (−)-(5R,6Z)-dendrolasin-5-acetate from the nudibranch Hypselodoris jacksoni

    PubMed Central

    Mudianta, I Wayan; Challinor, Victoria L; Winters, Anne E; Cheney, Karen L; De Voss, James J

    2013-01-01

    Summary A small sample of (−)-(5R,6Z)-dendrolasin-5-acetate, which was fully characterized by 2D NMR studies, was isolated from the nudibranch Hypselodoris jacksoni, along with the sesquiterpenes (+)-agassizin, (−)-furodysinin, (−)-euryfuran, (−)-dehydroherbadysidolide and (+)-pallescensone. A synthetic sample ([α]D −8.7) of the new metabolite was prepared by [1,2]-Wittig rearrangement of a geranylfuryl ether followed by acetylation of purified alcohol isomers. The absolute configuration at C-5 was established as R by the analysis of MPA ester derivatives of (Z)-5-hydroxydendrolasin obtained by preparative enantioselective HPLC. PMID:24454572

  11. Method for determining the concentration of atomic species in gases and solids

    DOEpatents

    Loge, Gary W.

    1998-01-01

    Method for determining the concentration of atomic species in gases and solids. Measurement of at least two emission intensities from a species in a sample that is excited by incident laser radiation. Which generates a plasma therein after a sufficient time period has elapsed and during a second time period, permits an instantaneous temperature to be established within the sample. The concentration of the atomic species to be determined is then derived from the known emission intensity of a predetermined concentration of that species in the sample at the measured temperature, a quantity which is measured prior to the determination of the unknown concentration, and the actual measured emission from the unknown species, or by this latter emission and the emission intensity of a species having known concentration within the sample such as nitrogen for gaseous air samples.

  12. Method for determining the concentration of atomic species in gases and solids

    DOEpatents

    Loge, G.W.

    1998-02-03

    Method is described for determining the concentration of atomic species in gases and solids. The method involves measurement of at least two emission intensities from a species in a sample that is excited by incident laser radiation. This generates a plasma therein after a sufficient time period has elapsed and during a second time period, permits an instantaneous temperature to be established within the sample. The concentration of the atomic species to be determined is then derived from the known emission intensity of a predetermined concentration of that species in the sample at the measured temperature, a quantity which is measured prior to the determination of the unknown concentration, and the actual measured emission from the unknown species, or by this latter emission and the emission intensity of a species having known concentration within the sample such as nitrogen for gaseous air samples. 4 figs.

  13. Method for determining the concentration of atomic species in gases and solids

    DOEpatents

    Loge, Gary W.

    1999-01-01

    Method for determining the concentration of atomic species in gases and solids. Measurement of at least two emission intensities from a species in a plasma containing the species after a sufficient time period has elapsed after the generation of the plasma and during a second time period, permits an instantaneous temperature to be established within the sample. The concentration of the atomic species to be determined is then derived from the known emission intensity of a predetermined concentration of that species in the sample at the measured temperature, a quantity which is measured prior to the determination of the unknown concentration, and the actual measured emission from the unknown species, or by this latter emission and the emission intensity of a species having known concentration within the sample.

  14. Determination of water quality variables, endotoxin concentration, and Enterobacteriaceae concentration and identification in southern High Plains dairy lagoons.

    PubMed

    Purdy, C W; Clark, R N; Straus, D C

    2010-04-01

    The objectives of this study were to determine the concentration of endotoxin, determine 20 water quality variables, and identify and enumerate fungal and bacterial pathogens from United States southern High Plains dairy lagoons and control lakes during summer and winter. Water samples were collected in triplicate from the north, south, east, and west quadrants of each body of water. The mean (+/- SEM) winter dairy lagoon endotoxin concentration was significantly higher (9,678+/-1,834 ng/mL) than the summer concentration (3,220+/-810 ng/mL). The mean endotoxin concentration of the 2 control lakes (summer: 58.1+/-8.8 ng/mL; winter: 38.6+/-4.2 ng/mL) was significantly less than that of the dairy lagoons. Two hundred-one Salmonella enterica spp. isolates were identified, 7 serovars were recovered from the dairy lagoons, and 259 Salmonella ssp. were identified from 5 other dairy locations (milk barn, ditch effluent, settling basin, feed alley pad flush, and center pivots). Twenty-eight Salmonella spp. were identified from center pivot water. Escherichia coli O157:H7 pathogens were isolated from other dairy locations but not from lagoons. Neither Salmonella spp. nor E. coli O157:H7 were identified from control lakes. Enterobacteriaceae opportunistic pathogens were isolated from both dairies and control lakes. Important mesophilic and thermophilic catabolic (to manure biosolids) fungal isolates were identified from dairy effluent locations, but no thermophilic fungal isolates were cultured from the control lakes. Adequate curing of green forage following center pivot irrigation is important to kill lagoon water enteric pathogens, even though the lagoon water is mixed with fresh water. Recirculating lagoon water to flush the feed alley pad, where cows stand while eating, to remove manure and using lagoon water to abate dairy dust in loafing pens and unimproved dairy roads is inconsistent with good environmental practice management. PMID:20338428

  15. The determination of the global average OH concentration using a deuteroethane tracer

    NASA Technical Reports Server (NTRS)

    Stevens, Charles M.; Cicerone, Ralph

    1986-01-01

    It is proposed to measure the decreasing global concentration of an OH reactive isotopic tracer, G sub 2 D sub 6, after its introduction into the troposphere in a manner to facilitate uniform global mixing. Analyses at the level of 2 x 10 to the -19th power fraction, corresponding to one kg uniformly distributed globally, should be possible by a combination of cryogenic absorption techniques to separate ethane from air and high sensitivity isotopic analysis of ethane by mass spectrometry. Aliquots of C sub 2 D sub 6 totaling one kg would be introduced to numerous southern and northern latitudes over a 10 day period in order to achieve a uniform global concentration within 3 to 6 months by the normal atmospheric circulation. Then samples of air of 1000 l (STP) would be collected periodically at a tropical and temperate zone location in each hemisphere and spiked with a known amount of another isotopic species of ethane, C-13 sub 2 H sub 6, at the level of 10 to the -11th power mole fraction. After separation of the ethanes from air, the absolute concentration of C sub 2 D sub 6 would be analyzed using the Argonne 100-inch radius mass spectrometer.

  16. Determination of refractive index and concentration of iodine solutions using opals

    NASA Astrophysics Data System (ADS)

    Kępińska, Mirosława; Starczewska, Anna; Szala, Janusz

    2014-03-01

    The determination of refractive index of iodine-ethanol solutions using SiO2 opals has been presented. For the first time concentration of solution iodine in ethanol has been determined by applying a simple method of using opal and de Feijter's relation. Basing on wavelength of diffraction peaks the appropriate formula describing concentration of iodine ethanol solution has been evolved. The uncertainty of the determined concentration has been established, too. The coefficient dnc/dC = 0.0201(4) (% w/w-1) of the linear dependence between refractive index and the concentration of iodine solution has been determined. The procedure of calibration of the used opal sensor is described. The opal sensor is not distracted by the measurement and can be used repeatedly.

  17. Continuous Determination of High-Vapor Phase Concentrations of Tetrachloroethylene Using On-Line Mass Spectrometry

    EPA Science Inventory

    A method was developed to determine the vapor concentration of tetrachloroethylene (PCE) at and below its equilibrium vapor phase concentration, 168,000 μg/L (25°C). Vapor samples were drawn by vacuum into a six-port sampling valve and injected through a jet separator into an io...

  18. Determining How Atmospheric Carbon Dioxide Concentrations Have Changed during the History of the Earth

    ERIC Educational Resources Information Center

    Badger, Marcus P. S.; Pancost, Richard D.; Harrison, Timothy G.

    2011-01-01

    The reconstruction of ancient atmospheric carbon dioxide concentrations is essential to understanding the history of the Earth and life. It is also an important guide to identifying the sensitivity of the Earth system to this greenhouse gas and, therefore, constraining its future impact on climate. However, determining the concentration of…

  19. 40 CFR 761.358 - Determining the PCB concentration of samples of waste.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Determining the PCB concentration of samples of waste. 761.358 Section 761.358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... concentration of samples of waste. Use either Method 3500B/3540C or Method 3500B/3550B from EPA's SW-846,...

  20. Determination of folate concentrations in diverse potato germplasm using a trienzyme extraction and microbiological assay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We determined total folate concentrations of potato tubers from 67 cultivars, advanced breeding lines, or wild species. Folates were extracted by a tri-enzyme treatment and analyzed by using a Lactobacillus rhamnosus microbiological assay. Folate concentrations varied from 521 ± 96 to 1373 ± 230 ng/...

  1. BUBBLE STRIPPING TO DETERMINE HYDROGEN CONCENTRATIONS IN GROUND WATER: A PRACTICAL APPLICATION OF HENRY'S LAW

    EPA Science Inventory

    The Bubble Stripping Method is a chemical testing method that operates on the principle of Henry's Law. It is useful for determining concentrations of hydrogen in well water, and it is capable of detecting concentrations on the order of nanomoles per liter. The method provides ...

  2. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  3. Synthesis and determination of absolute configuration of a non-peptidic αvβ6 integrin antagonist for the treatment of idiopathic pulmonary fibrosis.

    PubMed

    Anderson, Niall A; Campbell, Ian B; Fallon, Brendan J; Lynn, Sean M; Macdonald, Simon J F; Pritchard, John M; Procopiou, Panayiotis A; Sollis, Steven L; Thorp, Lee R

    2016-07-01

    A diastereoselective synthesis of (S)-3-(3-(3,5-dimethyl-1H-pyrazol-1-yl)phenyl)-4-((R)-3-(2-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)ethyl)pyrrolidin-1-yl)butanoic acid (1), a potential therapeutic agent for the treatment of Idiopathic Pulmonary Fibrosis, which is currently undergoing Phase I clinical trials is reported. The key steps in the synthesis involved alkylation of 2-methylnaphthyridine with (R)-N-Boc-3-(iodomethyl)-pyrrolidine, and an asymmetric Rh-catalysed addition of an arylboronic acid to a 4-(N-pyrrolidinyl)crotonate ester. The overall yield of the seven linear step synthesis was 8% and the product was obtained in >99.5% ee proceeding with 80% de. The absolute configuration of 1 was established by an alternative asymmetric synthesis involving alkylation of an arylacetic acid using Evans oxazolidinone chemistry, acylation using the resulting 2-arylsuccinic acid, and reduction. The absolute configuration of the benzylic asymmetric centre was established as (S). PMID:27226381

  4. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  5. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  6. LC/ESI-MS/MS method for determination of salivary eicosapentaenoic acid concentration to arachidonic acid concentration ratio.

    PubMed

    Ogawa, Shoujiro; Tomaru, Koki; Matsumoto, Nagisa; Watanabe, Shui; Higashi, Tatsuya

    2016-01-01

    A simple liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for determination of the eicosapentaenoic acid (EPA) concentration to arachidonic acid (AA) concentration ratio in human saliva has been developed. The EPA/AA ratio in serum or plasma is widely recognized as a useful indicator in identifying the risk of cardiovascular disease, especially atherosclerosis. The salivary EPA/AA ratio is expected to be a convenient alternative to the serum or plasma EPA/AA ratio, because saliva offers the advantages of easy and noninvasive sampling. The saliva was deproteinized with acetonitrile, purified using an Oasis HLB cartridge, and derivatized with 1-[(4-dimethylaminophenyl)carbonyl]piperazine (DAPPZ). The derivatized EPA and AA were subjected to LC/ESI-MS/MS, and the EPA/AA ratio was determined using the selected reaction monitoring mode. The DAPPZ-derivatization increased the ESI sensitivity by 100- and 300-fold for EPA and AA, respectively, and enabled the detection of trace fatty acids in saliva using a 200 μL sample. The assay reproducibility was satisfactory (relative standard deviation, <5.0%). The method was successfully applied to the measurement of the salivary EPA/AA ratios of healthy Japanese subjects and their changes owing to the supplementation of EPA. PMID:25620210

  7. Automated urinalysis technique determines concentration of creatine and creatinine by colorimetry

    NASA Technical Reports Server (NTRS)

    Rho, J. H.

    1967-01-01

    Continuous urinalysis technique is useful in the study of muscle wastage in primates. Creatinine concentration in urine is determined in an aliquot mixture by a color reaction. Creatine is determined in a second aliquot by converting it to creatinine and measuring the difference in color intensity between the two aliquots.

  8. What determines the calcium concentration of speleothem-forming drip waters?

    NASA Astrophysics Data System (ADS)

    Baker, Andy; Flemons, Ingrid; Andersen, Martin S.; Coleborn, Katie; Treble, Pauline C.

    2016-08-01

    Cave drip water calcium ion concentration is a primary determinant of speleothem deposition and growth rate. The factors that determine drip water calcium ion concentrations are the soil and vadose zone CO2 concentrations, and the hydrogeochemical evolution of the water from soil to cave. Here, we use a systematic literature review of cave drip water calcium concentrations, combined with PHREEQC equilibrium modelling, to investigate the global relationship between calcium concentration and surface climate. Our results are discussed in the context of understanding the climatic and environmental controls on drip water calcium concentration, speleothem growth rates and proxies of past climate and environmental change. We use an empirical, global soil CO2 concentration-temperature relationship to derive PHREEQC modelled cave drip water calcium concentrations. The global mean modelled drip water calcium concentration is close to that observed, but it over-predicts at high and low temperatures, and significantly under-predicts at temperate conditions. We hypothesise that closed system hydrochemical evolution due to water saturation is an important control on carbonate dissolution at colder temperatures. Under warmer conditions, for example temperate climates with a dry and hot or warm summer, seasonally-limited water availability can lead to: < 100% soil cover; water-limitations on microbial and root respiration; wildfire; and prior calcite precipitation, all of which limit drip water calcium concentrations. In temperate climates with no dry season, higher CO2 concentrations than modelled from soil values are necessary to explain the observed drip water calcium values, which we propose is from an additional source of CO2 from microbial activity and root respiration in the vadose zone during open system hydrochemical evolution.

  9. Development of a consensus standard for determining thermal performance of high-concentration-ratio solar collectors

    NASA Astrophysics Data System (ADS)

    Blackmon, J. B.; Linskens, M. C.; Reed, K. A.

    1982-12-01

    Consensus standard test method, for determining the thermal performance of concentrating solar collectors is described. The method applies to outdoor testing of one or two axis concentrating collectors with heat fluids for use in thermal systems and whose design is such that the effects of diffuse sky irradiance is negligible. The procedures determine the optical response of the collector for various angles of incidence of solar radiation, and the thermal performance of the collector at various operating temperatures for the condition of maximum optical response. The method requires quasi steady state conditions, measurement of enviromental parameters, and determination of the fluidmass flow rate specific heat product and temperature difference of the heat transfer fluid between the inlet and outlet of the collector. These quantities determine the rate of heat gain for the solar irradiance condition encountered. Thermal performance is determined as the rate of heat gain of the collector relative to the solar power incident on the plane of the collector aperture.

  10. Determination of free iodine concentration in an X-ray contrast agent

    NASA Astrophysics Data System (ADS)

    Kljubin, V. V.; Kljubina, K. A.; Makovetskaya, K. N.

    2016-04-01

    Based on the analysis of the absorption spectra of solutions of iodine in ethanol, we propose a simple and sensitive (at a level of 1 μg/g) method for determination of the concentration of free (not bound to polymer) iodine in substances synthesized from ether oils and iodine. The method uses absorption of molecular iodine in the UV region. Iodine dissolved in alcohols has a rather large absorption cross section in the UV region. These absorption bands can be used to detect very small quantities of iodine. It is shown that, for iodine concentrations in the 1-50 μg/g range, the intensity of absorption band at a wavelength of 359 nm depends linearly on the iodine concentration, which allows one to use this band to determine the concentration of iodine not bound with the polymer in the X-ray contrast material.

  11. Practical wet oxidation experiment to determine concentrations of particulate organic matter in seawater

    NASA Astrophysics Data System (ADS)

    Berger, V. Ya.; Mityaev, M. V.; Sukhotin, A. A.

    2016-03-01

    The report presents results of experiments testifying to the possibility of using wet oxidation to determine the concentrations of organic carbon in marine particulate matter. We describe a method for eliminating the measurement error caused by the influence of chlorides on the processes of dichromate oxidation of organic matter. We present an equation to calculate the concentration of organic carbon depending on that of sodium chloride.

  12. Emission spectrographic determination of barium in sea water using a cation exchange concentration procedure

    USGS Publications Warehouse

    Szabo, B. J.; Joensuu, O.

    1967-01-01

    A concentration technique employing Dowex 50W cation exchange resin is described for the determination of barium in sea water. The separated barium is precipitated as fluoride together with calcium and strontium and measured by emission spectrographic analysis. The vertical distribution of barium in sea water has been measured in the Caribbean Sea and the Atlantic Ocean. The barium content varied between 7 and 23 ??g. per liter; in two profiles, the lowest concentrations were at a depth of about 1000 meters.

  13. Determining analyte concentrations in plutonium metal by x-ray fluorescence using a dried residue method

    NASA Astrophysics Data System (ADS)

    Worley, Christopher G.; Havrilla, George J.

    2000-07-01

    Accurately determining the concentration of certain elements in plutonium is of vital importance in manufacturing nuclear weapons. X-ray fluorescence (XRF) provides a means of obtaining this type of elemental information accurately, quickly, with high precision, and often with little sample preparation. In the present work, a novel method was developed to analyze the gallium concentration in plutonium samples using wavelength-dispersive XRF. A description of the analytical method will be discussed.

  14. Validation of Ogawa passive samplers for the determination of gaseous ammonia concentrations in agricultural settings

    NASA Astrophysics Data System (ADS)

    Roadman, M. J.; Scudlark, J. R.; Meisinger, J. J.; Ullman, W. J.

    The Ogawa passive sampler (Ogawa USA, Pompano Beach, Florida) is a useful tool for monitoring atmospheric ammonia (NH 3(g)) concentrations and assessing the effects of agricultural waste management practices on NH 3(g) emissions. The Ogawa sampler, with filter-discs impregnated with citric acid, was used to trap and determine NH 3(g) concentrations in a variety of agricultural settings. A wide range of NH 3(g) concentrations can be monitored by varying the sampler exposure time, provided that no more than ˜10 μg of NH 3-N are adsorbed on the acid-coated filters. Concentrations less than 1 μg NH 3-N m -3 can be detected using long deployments (⩽14 days), while concentrations as great as 10 mg NH 3-N m -3 may be determined in very short (e.g. 5 min) deployments. Reproducibility ranged from 5% to 10% over the range of concentrations studied and passive determinations of NH 3(g) were similar to those determined using dilute-acid gas scrubbers. Background levels of NH 3(g) at a non-agricultural site in southern Delaware were typically <1 μg NH 3-N m -3. The air entering a chicken house was 10 μg NH 3-N m -3, reflecting the background levels in agricultural settings in this region. Within the house, concentrations ⩽8.5 mg NH 3-N m -3 were observed, reflecting the high rates of NH 3(g) emission from chicken excreta. Using measured NH 3(g) concentrations and poultry house ventilation rates, we estimate that each broiler grown to production size over 6 weeks contributes approximately 19±3 g of NH 3-N to the atmosphere, a value consistent with other published results.

  15. Correlations among experimental and theoretical NMR data to determine the absolute stereochemistry of darcyribeirine, a pentacyclic indole alkaloid isolated from Rauvolfia grandiflora

    NASA Astrophysics Data System (ADS)

    Cancelieri, Náuvia Maria; Ferreira, Thiago Resende; Vieira, Ivo José Curcino; Braz-Filho, Raimundo; Piló-Veloso, Dorila; Alcântara, Antônio Flávio de Carvalho

    2015-10-01

    Darcyribeirine (1) is a pentacyclic indole alkaloid isolated from Rauvolfia grandiflora. Stereochemistry of 1 was previously proposed based on 1D (coupling constant data) and 2D (NOESY correlations) NMR techniques, having been established a configuration 3R, 15S, and 20R (isomer 1a). Stereoisomers of 1 (i.e., 1a-1h) can be grouped into four sets of enantiomers. Carbon chemical shifts and hydrogen coupling constants were calculated using BLYP/6-31G* theory level for the eight isomers of 1. Calculated NMR data of 1a-1h were correlated with the corresponding experimental data of 1. The best correlations between theoretical and experimental carbon chemical shift data were obtained for the set of enantiomers 1e/1f to structures in the gaseous phase and considering solvent effects (using PCM and explicit models). Similar results were obtained when the same procedure was performed to correlations between theoretical and experimental coupling constant data. Finally, optical rotation calculations indicate 1e as its absolute stereochemistry. Orbital population analysis indicates that the hydrogen bonding between N-H of 1e and DMSO is due to contributions of its frontier unoccupied molecular orbitals, mainly LUMO+1, LUMO+2, and LUMO+3.

  16. Determination of Delta m(d) and absolute calibration of flavor taggers for the Delta m(s) analysis, in fully reconstructed decays at the CDF experiment

    SciTech Connect

    Gomez, Jonatan Piedra

    2005-07-01

    The new trigger processor, the Silicon Vertex Tracking (SVT), has dramatically improved the B physics capabilities of the upgraded CDF II Detector; for the first time in a hadron collider, the SVT has enabled the access to non-lepton-triggered B meson decays. Within the new available range of decay modes, the B{sub s}{sup 0} {yields} D{sub s}{sup -}{pi}{sup +} signature is of paramount importance in the measurement of the {Delta}m{sub s} mixing frequency. The analysis reported here is a step towards the measurement of this frequency; two where our goals: carrying out the absolute calibration of the opposite side flavor taggers, used in the {Delta}m{sub s} measurement; and measuring the B{sub d}{sup 0} mixing frequency in a B {yields} D{pi} sample, establishing the feasibility of the mixing measurement in this sample whose decay-length is strongly biased by the selective SVT trigger. We analyze a total integrated luminosity of 355 pb{sup -1} collected with the CDF II Detector. By triggering on muons, using the conventional di-muon trigger; or displaced tracks, using the SVT trigger, we gather a sample rich in bottom and charm mesons.

  17. Determination of absolute value of quantum efficiency of radiation in high quality GaN single crystals using an integrating sphere

    NASA Astrophysics Data System (ADS)

    Kojima, Kazunobu; Ohtomo, Tomomi; Ikemura, Ken-ichiro; Yamazaki, Yoshiki; Saito, Makoto; Ikeda, Hirotaka; Fujito, Kenji; Chichibu, Shigefusa F.

    2016-07-01

    Omnidirectional photoluminescence (ODPL) measurement using an integrating sphere was carried out to absolutely quantify the quantum efficiency of radiation ( η) in high quality GaN single crystals. The total numbers of photons belonging to photoluminescence (PL photons) and photons belonging to an excitation source (excitation photons) were simultaneously counted in the measurement, and η was defined as a ratio of the number of PL photons to the number of absorbed excitation photons. The ODPL spectra near the band edge commonly showed a two-peak structure, which originates from the sharp absorption edge of GaN. A methodology for quantifying internal quantum efficiency ( ηint ) from such experimentally obtained η is derived. A record high ηint of typically 15% is obtained for a freestanding GaN crystal grown by hydride vapor phase epitaxy on a GaN seed crystal synthesized by the ammonothermal method using an acidic mineralizer, when the excitation photon energy and power density were 3.81 eV and 60 W/cm2, respectively.

  18. Simultaneous and rapid determination of multiple component concentrations in a Kraft liquor process stream

    SciTech Connect

    Li, Jian; Chai, Xin Sheng; Zhu, Junyoung

    2008-06-24

    The present invention is a rapid method of determining the concentration of the major components in a chemical stream. The present invention is also a simple, low cost, device of determining the in-situ concentration of the major components in a chemical stream. In particular, the present invention provides a useful method for simultaneously determining the concentrations of sodium hydroxide, sodium sulfide and sodium carbonate in aqueous kraft pulping liquors through use of an attenuated total reflectance (ATR) tunnel flow cell or optical probe capable of producing a ultraviolet absorbency spectrum over a wavelength of 190 to 300 nm. In addition, the present invention eliminates the need for manual sampling and dilution previously required to generate analyzable samples. The inventive method can be used in Kraft pulping operations to control white liquor causticizing efficiency, sulfate reduction efficiency in green liquor, oxidation efficiency for oxidized white liquor and the active and effective alkali charge to kraft pulping operations.

  19. Non-Adiabatic Mechanism for Photosynthetic Energy Transfer and All-Optical Determination of Concentration using Femtosecond Lasers

    NASA Astrophysics Data System (ADS)

    Tiwari, Vivek

    2015-05-01

    Understanding the fundamental physics of light-harvesting in both, natural and artificial systems is key for the development of efficient light-harvesting technologies. My thesis addresses the following topics, i.) the mechanism underlying the remarkably efficient electronic energy transfer in natural light harvesting antennas, ii.) a femtosecond time-resolved photonumeric technique to quantitatively characterize transient chemical species. This talk will concentrate on the first project, while briefly touching the key ideas of the second project. Light harvesting antennas use a set of closely spaced pigment molecules held in a controlled relative geometry by a protein. It is shown that in certain antenna proteins the excited state electronic energy gaps between the pigments are resonant with a quantum of pigment vibrational energy. With such a vibrational-electronic resonance, anti-correlated motions between the pigments lead to a strong coupling between the electronic and nuclear motions, that is, breakdown of the Born-Oppenheimer approximation, over a wide range of pigment vibrational motions. It is shown that the 2D spectroscopic signatures of the resulting unavoidable nested non-adiabatic energy funnel on the excited states of photosynthetic antennas are consistent with all the reported 2D signatures of long-lived coherent oscillations, including the ones that are not explained by prior models of excited state electronic energy transfer. Extensions that account for both resonant and near-resonant pigment vibrations suggest that photosynthetic energy transfer presents a novel design in which electronic energy transfer proceeds non-adiabatically through clusters of vibrations with frequencies distributed around electronic energy gaps. I will also briefly talk about our experiments demonstrating quantitative time-resolved measurement of absolute number of excited state molecules. Based on these measurements, an all-optical technique that simultaneously determines

  20. Determination of the critical micelle concentration in simulations of surfactant systems

    NASA Astrophysics Data System (ADS)

    Santos, Andrew P.; Panagiotopoulos, Athanassios Z.

    2016-01-01

    Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the "free" (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit).

  1. Determination of tungsten and molybdenum concentrations from an x-ray range spectrum in JET with the ITER-like wall configuration

    NASA Astrophysics Data System (ADS)

    Nakano, T.; Shumack, A. E.; Maggi, C. F.; Reinke, M.; Lawson, K. D.; Coffey, I.; Pütterich, T.; Brezinsek, S.; Lipschultz, B.; Matthews, G. F.; Chernyshova, M.; Jakubowska, K.; Scholz, M.; Rzadkiewicz, J.; Czarski, T.; Dominik, W.; Kasprowicz, G.; Pozniak, K.; Zabolotny, W.; Zastrow, K.-D.; Conway, N. J.; contributors, JET

    2015-07-01

    The {{W}45+} and {{W}46+} 3p-4d inner shell excitation lines in addition to M{{o}32+} 2p-3s lines have been identified from the spectrum taken by an upgraded high-resolution x-ray spectrometer. It is found from analysis of the absolute intensities of the {{W}46+} and M{{o}32+} lines that W and Mo concentrations are in the range of ˜ {{10}-5} and ˜ {{10}-6}, respectively, with a ratio of ˜5% in JET with the ITER-like wall configuration for ELMy H-mode plasmas with a plasma current of 2.0-2.5 MA, a toroidal magnetic field of 2.7 T and a neutral beam injection power of 14-18 MW. For the purpose of checking self-consistency, it is confirmed that the W concentration determined from the {{W}45+} line is in agreement with that from the {{W}46+} line within 20% and that the plasma effective charge determined from the continuum of the first order reflection spectrum is also in agreement with that from the second order within 50%. Further, the determined plasma effective charge is in agreement with that determined from a visible spectroscopy, confirming that the sensitivity of the x-ray spectrometer is valid and that the W and the Mo concentrations are also likely to be valid.

  2. Occupational secondhand smoke is the main determinant of hair nicotine concentrations in bar and restaurant workers

    PubMed Central

    Iglesias, Verónica; Erazo, Marcia; Droppelmann, Andrea; Steenland, Kyle; Aceituno, Paulina; Orellana, Cecilia; Acuña, Marisol; Peruga, Armando; Breysse, Patrick N.; Navas-Acien, Ana

    2015-01-01

    Objective To evaluate the relative contribution of occupational vs. non-occupational secondhand tobacco smoke exposure to overall hair nicotine concentrations in non-smoking bar and restaurant employees. Method We recruited 76 non-smoking employees from venues that allowed smoking (n = 9), had mixed policies (smoking and non-smoking areas, n = 13) or were smoke-free (n = 2) between April and August 2008 in Santiago, Chile. Employees used personal air nicotine samplers during working and non-working hours for a 24-h period to assess occupational vs. non-occupational secondhand tobacco smoke exposure and hair nicotine concentrations to assess overall secondhand tobacco smoke exposure. Results Median hair nicotine concentrations were 1.5 ng/mg, interquartile range (IQR) 0.7 to 5.2 ng/mg. Time weighted average personal air nicotine concentrations were higher during working hours (median 9.7, IQR 3.3-25.4 μg/m3) compared to non-working hours (1.7, 1.0-3.1 μg/m3). Hair nicotine concentration was best predicted by personal air nicotine concentration at working hours. After adjustment, a 2-fold increase in personal air nicotine concentration in working hours was associated with a 42% increase in hair nicotine concentration (95% confidence interval 14-70%). Hair nicotine concentration was not associated with personal air nicotine concentration during non-working hours (non-occupational exposure). Conclusions Personal air nicotine concentration at working hours was the major determinant of hair nicotine concentrations in non-smoking employees from Santiago, Chile. Secondhand tobacco smoke exposure during working hours is a health hazard for hospitality employees working in venues where smoking is allowed. PMID:24813578

  3. Use of dried blood spots for the determination of serum concentrations of tamoxifen and endoxifen.

    PubMed

    Jager, N G L; Rosing, H; Schellens, J H M; Beijnen, J H; Linn, S C

    2014-07-01

    The anti-estrogenic effect of tamoxifen is suggested to be mainly attributable to its metabolite (Z)-endoxifen, and a minimum therapeutic threshold for (Z)-endoxifen in serum has been proposed. The objective of this research was to establish the relationship between dried blood spot (DBS) and serum concentrations of tamoxifen and (Z)-endoxifen to allow the use of DBS sampling, a simple and patient-friendly alternative to venous sampling, in clinical practice. Paired DBS and serum samples were obtained from 50 patients using tamoxifen and analyzed using HPLC-MS/MS. Serum concentrations were calculated from DBS concentrations using the formula calculated serum concentration = DBS concentration/([1-haematocrit (Hct)] + blood cell-to-serum ratio × Hct). The blood cell-to-serum ratio was determined ex vivo by incubating a batch of whole blood spiked with both analytes. The average Hct for female adults was imputed as a fixed value. Calculated and analyzed serum concentrations were compared using weighted Deming regression. Weighted Deming regression analysis comparing 44 matching pairs of DBS and serum samples showed a proportional bias for both analytes. Serum concentrations were calculated using [Tamoxifen] serum, calculated  = [Tamoxifen] DBS /0.779 and [(Z)-Endoxifen] serum, calculated = [(Z)-Endoxifen] DBS /0.663. Calculated serum concentrations were within 20 % of analyzed serum concentrations in 84 and 100 % of patient samples for tamoxifen and (Z)-endoxifen, respectively. In conclusion, DBS concentrations of tamoxifen and (Z)-endoxifen were equal to serum concentrations after correction for Hct and blood cell-to-serum ratio. DBS sampling can be used in clinical practice. PMID:24859000

  4. The Determination of the Concentrations of Sugar Solutions by Laser Refractometry.

    ERIC Educational Resources Information Center

    Hughes, Elvin, Jr.; And Others

    1988-01-01

    Presents an easily performed experiment to determine sucrose concentrations using a laser and a hollow glass prism. The experiment is suggested for high school, freshman college, and instrumental analysis classes. Notes an Erlenmeyer flask can be used instead of a prism. (MVL)

  5. 40 CFR 761.358 - Determining the PCB concentration of samples of waste.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Determining the PCB concentration of..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Sampling Non-Liquid, Non-Metal PCB Bulk Product Waste for Purposes of Characterization for PCB Disposal in Accordance With § 761.62, and Sampling PCB...

  6. 40 CFR 761.358 - Determining the PCB concentration of samples of waste.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Determining the PCB concentration of..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Sampling Non-Liquid, Non-Metal PCB Bulk Product Waste for Purposes of Characterization for PCB Disposal in Accordance With § 761.62, and Sampling PCB...

  7. 40 CFR 761.358 - Determining the PCB concentration of samples of waste.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Determining the PCB concentration of..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Sampling Non-Liquid, Non-Metal PCB Bulk Product Waste for Purposes of Characterization for PCB Disposal in Accordance With § 761.62, and Sampling PCB...

  8. New method of determining the current carrier concentration in a substance in the state of superconductivity

    SciTech Connect

    Golotyuk, F.P.

    1985-08-02

    This report proposes a fundamentally new solution to the problem of determining the current carrier concentration in a substance. The basis of the corresponding experimental method is a theory that considers the electron drift energy when considering the oscillatory processes in certain circuits.

  9. Feasibility of field portable near infrared (NIR) spectroscopy to determine cyanide concentrations in soil

    NASA Astrophysics Data System (ADS)

    Sut, Magdalena; Fischer, Thomas; Repmann, Frank; Raab, Thomas

    2013-04-01

    In Germany, at more than 1000 sites, soil is polluted with an anthropogenic contaminant in form of iron-cyanide complexes. These contaminations are caused by former Manufactured Gas Plants (MGPs), where electricity for lighting was produced in the process of coal gasification. The production of manufactured gas was restrained in 1950, which caused cessation of MGPs. Our study describes the application of Polychromix Handheld Field Portable Near-Infrared (NIR) Analyzer to predict the cyanide concentrations in soil. In recent times, when the soil remediation is of major importance, there is a need to develop rapid and non-destructive methods for contaminant determination in the field. In situ analysis enables determination of 'hot spots', is cheap and time saving in comparison to laboratory methods. This paper presents a novel usage of NIR spectroscopy, where a calibration model was developed, using multivariate calibration algorithms, in order to determine NIR spectral response to the cyanide concentration in soil samples. As a control, the contaminant concentration was determined using conventional Flow Injection Analysis (FIA). The experiments revealed that portable near-infrared spectrometers could be a reliable device for identification of contamination 'hot spots', where cyanide concentration are higher than 2400 mg kg-1 in the field and >1750 mg kg-1 after sample preparation in the laboratory, but cannot replace traditional laboratory analyses due to high limits of detection.

  10. A SIMPLE TECHNIQUE FOR DETERMINING THE MAXIMUM GROUND LEVEL CONCENTRATION OF AN ELEVATED GASEOUS RELEASE

    EPA Science Inventory

    The paper describes the development of a screening technique to determine the maximum 1 hour ground level concentration of a gaseous emission from a stack located in flat terrain. The method does not require the use of a computer and eliminates the usual trial and error calculati...

  11. Cefaclor pharmacokinetic parameters: serum concentrations determined by a new high-performance liquid chromatographic technique.

    PubMed

    Rotschafer, J C; Crossley, K B; Lesar, T S; Zaske, D; Miller, K

    1982-01-01

    Pharmacokinetic parameters of cefaclor were studied in eight patients after an oral dose of 250 mg. Serum samples were obtained before and on 19 occasions after oral administration. Cefaclor serum concentrations were determined by a new high-performance liquid chromatographic technique. PMID:7081972

  12. Using Conductivity Measurements to Determine the Identities and Concentrations of Unknown Acids: An Inquiry Laboratory Experiment

    ERIC Educational Resources Information Center

    Smith, K. Christopher; Garza, Ariana

    2015-01-01

    This paper describes a student designed experiment using titrations involving conductivity measurements to identify unknown acids as being either HCl or H[subscript 2]SO[subscript 4], and to determine the concentrations of the acids, thereby improving the utility of standard acid-base titrations. Using an inquiry context, students gain experience…

  13. Concentration method for the spectrochemical determination of seventeen minor elements in natural water

    USGS Publications Warehouse

    Silvey, W.D.; Brennan, R.

    1962-01-01

    A method for the quantitative spectrochemical determination of microgram amounts of 17 minor elements in water is given. The chelating reagents 8-quinolinol, tannic acid, and thionalide are utilized to concentrate traces (1 to 500 ??g.) of aluminum, cobalt, chromium, copper, iron, gallium, germanium, manganese, nickel, titanium, vanadium, bismuth, lead, molybdenum, cadmium, zinc, and beryllium. Indium is added as a buffer, and palladium is used as an internal standard. The ashed oxides of these 17 metals are subsequently subjected to direct current arcing conditions during spectrum analysis. The method can be used to analyze waters with dissolved solids ranging from less than 100 to more than 100,000 p.p.m. There is no limiting concentration range for the determination of the heavy metals since any volume of sample can be used that will contain a heavy metal concentration within the analytical range of the method. Both the chemical and spectrographic procedures are described, and precision and accuracy data are given.

  14. Determination of Methanol Concentrations in Traditional Herbal Waters of Different Brands in Iran

    PubMed Central

    Mousavi, Seyed Reza; Namaei-Ghassemi, Mohssen; Layegh, Massomeh; AfzalAghaee, Monavar; vafaee, Manssoreh; Zare, Gholamali; Moghiman, Toktam; Mood, Mahdi Balali

    2011-01-01

    Objective(s) Herbal waters are extensively used in most parts of including . Visiting a patient with total blindness due to daily ingestion of around 200 ml of herbal water (Plant forty water) per day for six months was the rational for methanol determination in all herbal waters available in markets. Materials and Methods A total of two hundred and nineteen bottles of herbal waters were randomly bought from market. Methanol concentration was determined by gas chromatography, using a Flame Ionized Detector. Benzene (1000 mg/l) was applied as the internal standard. Collected data was analyzed by SPSS software (version 11.5), using appropriate descriptive statistical tests. Results Forty six different herbal waters from three main producing factories (A, B and C) were tested. Highest methanol concentration was measured in dill water of A (1208±202.74 mg/l), concentrated rose water of A (1017.41±59.68 mg/l) and concentrated rose water of B (978.52±92.81 mg/l). Lowest methanol concentration was determined in Trachyspermum copticum water of B (18.93±1.04 mg/l), cinnamon and ginger water of B (29.64±10.88 mg/l) and rice skin water of A (41.33±7.85 mg/l). Mean methanol concentrations of herbal waters including ginger, cinnamon, dill, peppermint, alfalfa, and plant forty from A, B and C were 374.69, 209.81 and 280.12 mg/l, respectively (P< 0.001). Conclusion Methanol concentration in all herbal waters, especially rose water of the three producers was very high that may induce toxicity in people taking these products regularly for a long time. PMID:23493100

  15. Determination of indoor radon concentrations at the elementary schools of Fatih district in Istanbul

    NASA Astrophysics Data System (ADS)

    Kurt, A.; Yalcin, L. Sahin; Oktem, Y.; Akkus, B.; Bozkurt, E.; Hafizoglu, N.; Ozturk, F. C.; Aytan, O.; Ertoprak, A.

    2016-03-01

    Radon is an odorless, tasteless, colorless noble radioactive gas which is produced within the radioactive decay chain of Uranium. The Radon forms in rocks, diffuses into soil and then escapes into atmosphere. When human exposure to high concentration of radon gas from inside, risk of developing lung cancer is increased. There are many methods to determine 222Rn concentration in the air. In this study, radon concentration of confined air spaces were measured by using LR-115 solid state nuclear track detectors. 509 LR-115 nuclear trace detectors were placed to 25 schools in Fatih District and they effective dose values were calculated. The results of measurements showed that the radon concentration varies between 40-395 Bq/m3. This results compared with Turkey's limits (400 Bq/m3) are low, conversely higher compared with WHO's limits (100 Bq/m3).

  16. Lipase-catalyzed resolution of (2R*,3S*)- and (2R*,3R*)-3-methyl-3-phenyl-2-aziridinemethanol at low temperatures and determination of the absolute configurations of the four stereoisomers.

    PubMed

    Sakai, Takashi; Liu, Yu; Ohta, Hiroshi; Korenaga, Toshinobu; Ema, Tadashi

    2005-02-18

    [reaction: see text] Lipase-catalyzed resolution of (2R*,3S*)-3-methyl-3-phenyl-2-aziridinemethanol, (+/-)-2, at low temperatures gave synthetically useful (2R,3S)-2 and its acetate (2S,3R)-2a with (2S)-selectivity (E = 55 at -40 degrees C), while a similar reaction of (2R*,3R*)-3-methyl-3-phenyl-2-aziridinemethanol, (+/-)-3, gave (2S,3S)-3 and its acetate (2R,3R)-3a with (2R)-selectivity (E = 73 at -20 degrees C). Compound (+/-)-2 was prepared conveniently via diastereoselective addition of MeMgBr to tert-butyl 3-phenyl-2H-azirine-2-carboxylate, (+/-)-1a, which was successfully prepared by the Neber reaction of oxime tosylate of tert-butyl benzoyl acetate 7a. The tert-butyl ester was requisite to promote this reaction. For determination of the absolute configuration of (2S,3R)-2a, enantiopure (2S,3R)-2 was independently prepared in three steps involving diastereoselective methylation of 3-phenyl-2H-azirine-2-methanol, (S)-10, with MeMgBr. The absolute configuration of (2S,3S)-3 was determined by X-ray analysis of the corresponding N-(S)-2-(6-methoxy-2-naphthyl)propanoyl derivative (S,S,S)-13. PMID:15704972

  17. Novel method to determine element concentrations in foliage of poplar and willow cuttings.

    PubMed

    Evangelou, Michael W H; Bürgi, Annina; Robinson, Brett H; Günthardt-Goerg, Madeleine S; Schöngens, Marcel; Schulin, Rainer

    2016-09-01

    Measuring the uptake of the chemical elements by plants usually requires the destructive harvest of the plants. Analyzing individual leaves is unsatisfactory because their elemental concentration depends on their age and position on the branch or stem. We aimed to find an easy method to determine the elemental concentrations using a few suitable single leaves along the main shoot of poplar (Populus monviso) and willow (Salix viminalis) cuttings at the end of the first season. Using Ca, Cd, Mn, Fe, K, P, Pb, and Zn concentrations, measured in selected leaves along the main shoots of the cuttings, mathematical functions were derived, which described best their distribution. Elemental allocation patterns were independent of the soil characteristics and soil element concentrations. Based on these functions, three leaves from specific positions along the main shoot were selected, which could accurately describe the derived functions. The deviation of the calculated average concentration, based on the 3-leaves method, was ≤15% in approximately 65% of the cases compared to the measured concentration. This method could be used to calculate element concentrations and fluxes in phytomanagement, biomonitoring, or biomass productions projects using one-season poplar or willow cuttings. PMID:26691784

  18. CONTROL OF ANTIGEN MASS TRANSFER VIA CAPTURE SUBSTRATE ROTATION: AN ABSOLUTE METHOD FOR THE DETERMINATION OF VIRAL PATHOGEN CONCENTRATION AND REDUCTION OF HETEROGENEOUS IMMUNOASSAY INCUBATION TIMES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immunosorbent assays are commonly employed as diagnostic tests in human healthcare and veterinary medicine and are strongly relevant to the methodologies for bioterrorism detection. However, immunoassays often require long incubation times, limiting sample throughput. As an approach to overcome this...

  19. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  20. Molecular iodine absolute frequencies. Final report

    SciTech Connect

    Sansonetti, C.J.

    1990-06-25

    Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.

  1. Diurnal variation of phenylalanine and tyrosine concentrations in adult patients with phenylketonuria: subcutaneous microdialysis is no adequate tool for the determination of amino acid concentrations

    PubMed Central

    2013-01-01

    Background Metabolic control and dietary management of patients with phenylketonuria (PKU) are based on single blood samples obtained at variable intervals. Sampling conditions are often not well-specified and intermittent variation of phenylalanine concentrations between two measurements remains unknown. We determined phenylalanine and tyrosine concentrations in blood over 24 hours. Additionally, the impact of food intake and physical exercise on phenylalanine and tyrosine concentrations was examined. Subcutaneous microdialysis was evaluated as a tool for monitoring phenylalanine and tyrosine concentrations in PKU patients. Methods Phenylalanine and tyrosine concentrations of eight adult patients with PKU were determined at 60 minute intervals in serum, dried blood and subcutaneous microdialysate and additionally every 30 minutes postprandially in subcutaneous microdialysate. During the study period of 24 hours individually tailored meals with defined phenylalanine and tyrosine contents were served at fixed times and 20 min bicycle-ergometry was performed. Results Serum phenylalanine concentrations showed only minor variations while tyrosine concentrations varied significantly more over the 24-hour period. Food intake within the patients’ individual diet had no consistent effect on the mean phenylalanine concentration but the tyrosine concentration increased up to 300% individually. Mean phenylalanine concentration remained stable after short-term bicycle-exercise whereas mean tyrosine concentration declined significantly. Phenylalanine and tyrosine concentrations in dried blood were significantly lower than serum concentrations. No close correlation has been found between serum and microdialysis fluid for phenylalanine and tyrosine concentrations. Conclusions Slight diurnal variation of phenylalanine concentrations in serum implicates that a single blood sample does reliably reflect the metabolic control in this group of adult patients. Phenylalanine

  2. Determination of background concentrations for air quality models using spectral analysis and filtering of monitoring data

    NASA Astrophysics Data System (ADS)

    Tchepel, O.; Costa, A. M.; Martins, H.; Ferreira, J.; Monteiro, A.; Miranda, A. I.; Borrego, C.

    2010-01-01

    The use of background concentrations in air pollution modelling is usually a critical issue and a source of errors. The current work proposes an approach for the estimation of background concentrations using air quality measured data decomposed on baseline and short-term components. For this purpose, the spectral density was obtained for air quality monitoring data based on the Fourier series analysis. After, short-term fluctuations associated with the influence of local emissions and dispersion conditions were extracted from the original measurements using an iterative moving-average filter and taking into account the contribution of higher frequencies determined from the spectral analysis. The deterministic component obtained by the filtering is characterised by wider spatial and temporal representativeness than original monitoring data and is assumed to be appropriate for establishing the background values. This methodology was applied to define background concentrations of particulate matter (PM 10) used as input data for a local scale CFD model, and compared with an alternative approach using background concentrations provided by a mesoscale air quality modelling system. The study is focused on a selected domain within the Lisbon urban area (Portugal). The results present a better performance for the microscale model when initialised by decomposed time series and demonstrate the importance of the proposed methodology in reducing the uncertainty of the model predictions. The decomposition of air quality measurements and the removal of short-term fluctuations discussed in the work is a valuable technique to determine representative background concentrations.

  3. Neutron activation analysis of certified samples by the absolute method

    NASA Astrophysics Data System (ADS)

    Kadem, F.; Belouadah, N.; Idiri, Z.

    2015-07-01

    The nuclear reactions analysis technique is mainly based on the relative method or the use of activation cross sections. In order to validate nuclear data for the calculated cross section evaluated from systematic studies, we used the neutron activation analysis technique (NAA) to determine the various constituent concentrations of certified samples for animal blood, milk and hay. In this analysis, the absolute method is used. The neutron activation technique involves irradiating the sample and subsequently performing a measurement of the activity of the sample. The fundamental equation of the activation connects several physical parameters including the cross section that is essential for the quantitative determination of the different elements composing the sample without resorting to the use of standard sample. Called the absolute method, it allows a measurement as accurate as the relative method. The results obtained by the absolute method showed that the values are as precise as the relative method requiring the use of standard sample for each element to be quantified.

  4. Use of behavioral endpoints to determine protective concentrations of the insecticide fonofos for bluegill (Lepomis macrochirus)

    USGS Publications Warehouse

    Fairchild, J.F.; Little, E.E.

    1999-01-01

    This research compared the results of laboratory and mesocosm studies to determine the effectiveness of using behavioral measures of sublethal exposure to define environmental concentration ranges that are protective of free-ranging populations of bluegill (Lepomis macrochirus) exposed to the organophophate insecticide fonofos. Thirty-day laboratory chronic studies were conducted to determine the relative sensitivity of standard (e.g. survival and growth) and non-standard behavioral (e.g. swimming capacity, feeding efficiency, and aggression) endpoints in predicting concentrations of fonofos protective of bluegill growth and survival. The lowest observable effect concentration (LOECs) for the standard measures of survival and growth was 5.6 ??g/L. Two behavioral endpoints were of similar sensitivity to the standard measures: swimming capacity, LOEC of 5.6 ??g/L; and prey strike frequency, LOEC of 5.6 ??g/L. However, aggressive interactions were ten-fold more sensitive than swimming or feeding behavior with a LOEC occurring at 0.6 ??g/L. Lab results were compared to an aquatic mesocosm study which exposed adult and juvenile bluegill to a 9.41 ??g/L concentration of fonofos. The dissipation half-life of fonofos was 5 days in 0.1 hectare aquatic mesocosms. Significant mortality among caged bluegill occurred within 4 days of exposure at 9.41 ??g/L. However, the 9.41 ??g/L concentration of fonofos had no statistically significant effects on survival, growth, reproduction, or total biomass of free-ranging populations of bluegill. We conclude from these studies that laboratory data can accurately estimate concentrations that are lethal in the field and that the use of behavioral endpoints can provide ecologically relevant, yet conservative estimates of concentrations that are protective of field populations.

  5. A simplified CARS measurement system for rapid determination of temperature and oxygen concentration

    NASA Technical Reports Server (NTRS)

    Fujii, Shoichi

    1987-01-01

    A new spectroscopic concept for the rapid determination of temperature and oxygen concentration by CARS (Coherent Anti-Stokes Raman Spectroscopy) was described. The ratio of two spectral regions in the broadband Q-branch spectrum was detected by photomultipliers in a monochromator, which ratio depends on temperature and species concentration. The comparison of the measured data with theory was made using a flat flame burner and an electric furnace, with reasonable results. Various optical techniques for alignment were introduced including a highly efficient, stable dye oscillator. The combination of the spectroscopic concept and the optical techniques will make the CARS measurement system rapid in data processing and simple in optical parts.

  6. Determination of uranium concentration in ground water samples of Northern Greece

    NASA Astrophysics Data System (ADS)

    Samaropoulos, I.; Efstathiou, M.; Pashalidis, I.; Ioannidou, A.

    2012-04-01

    The activity concentration of 238U and 234U has been determined in groundwater samples of hot springs and deep wells from the region of Northern Greece. The analysis was performed by alpha spectroscopy after pre-concentration and separation of uranium by cation exchange (Chelex 100 resin) and finally its electro-deposition on stainless steel discs. The uranium concentration in deep wells and springs varies strongly between 0.15 and 7.66 μg l-1. Generally the springs present higher uranium concentration than the deep wells, except of the Apol-lonia spring, which has shown the lowest value of 0.15 mg l-1. 238U and 234U activity concentration ranged between 1.8-95.3 mBq l-1 and 1.7-160.1 mBq l-1, respectively. The obtained isotopic ratio 234U/238U varies between 0.95 and 1.74 which means that the two isotopes are not in radioactive equilibrium. The highest 234U/238U activity ratio values correspond to the Langada springs, indicating most probably old-type waters. On the other hand, ground waters from wells with relatively low uranium activity concentration and low 234U/238U isotopic ratios, point to the presence of younger waters with a stronger contribution of a local recharge component to the groundwater.

  7. Implants as absolute anchorage.

    PubMed

    Rungcharassaeng, Kitichai; Kan, Joseph Y K; Caruso, Joseph M

    2005-11-01

    Anchorage control is essential for successful orthodontic treatment. Each tooth has its own anchorage potential as well as propensity to move when force is applied. When teeth are used as anchorage, the untoward movements of the anchoring units may result in the prolonged treatment time, and unpredictable or less-than-ideal outcome. To maximize tooth-related anchorage, techniques such as differential torque, placing roots into the cortex of the bone, the use of various intraoral devices and/or extraoral appliances have been implemented. Implants, as they are in direct contact with bone, do not possess a periodontal ligament. As a result, they do not move when orthodontic/orthopedic force is applied, and therefore can be used as "absolute anchorage." This article describes different types of implants that have been used as orthodontic anchorage. Their clinical applications and limitations are also discussed. PMID:16463910

  8. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  9. Absolute determination of charge-coupled device quantum detection efficiency using Si K-edge x-ray absorption fine structure

    SciTech Connect

    Dunn, J; Steel, A B

    2012-05-06

    We report a method to determine the quantum detection efficiency and the absorbing layers on a front-illuminated charge-coupled device (CCD). The CCD under study, as part of a crystal spectrometer, measures intense continuum x-ray emission from a picosecond laser-produced plasma and spectrally resolves the Si K-edge x-ray absorption fine structure features due to the electrode gate structure of the device. The CCD response across the Si K-edge shows a large discontinuity as well as a number of oscillations that are identified individually and uniquely from Si, SiO{sub 2}, and Si{sub 3}N{sub 4} layers. From the spectral analysis of the structure and K-edge discontinuity, the active layer thickness and the different absorbing layers thickness can be determined precisely. A precise CCD detection model from 0.2-10 keV can be deduced from this highly sensitive technique.

  10. Apparatus for the field determination of concentration of radioactive constituents in a medium

    DOEpatents

    Perkins, R.W.; Schilk, A.J.; Warner, R.A.; Wogman, N.A.

    1995-08-15

    The instant invention is an apparatus for determining the concentration of radioactive constituents in a test sample; such as surface soils, via rapid real-time analyses, and direct readout on location utilizing a probe made up of multiple layers of detection material used in combination with an analyzer and real-time readout unit. This is accomplished by comparing the signal received from the probe, which can discriminate between types of radiation and energies with stored patterns that are based upon experimental results. This comparison can be used in the calibration of a readout display that reads out in real-time the concentrations of constituents per given volume. For example, the concentration of constituents such as Cs-137, Sr-90, U-238 in the soil, and noble gas radionuclides such as Kr-85 in the atmosphere, can be measured in real-time, on location, without the need for laboratory analysis of samples. 14 figs.

  11. Apparatus for the field determination of concentration of radioactive constituents in a medium

    DOEpatents

    Perkins, Richard W.; Schilk, Alan J.; Warner, Ray A.; Wogman, Ned A.

    1995-01-01

    The instant invention is an apparatus for determining the concentration of radioactive constituents in a test sample; such as surface soils, via rapid real-time analyses, and direct readout on location utilizing a probe made up of multiple layers of detection material used in combination with an analyzer and real-time readout unit. This is accomplished by comparing the signal received from the probe, which can discriminate between types of radiation and energies with stored patterns that are based upon experimental results. This comparison can be used in the calibration of a readout display that reads out in real-time the concentrations of constituents per given volume. For example, the concentration of constituents such as Cs-137, Sr-90, U-238 in the soil, and noble gas radionuclides such as Kr-85 in the atmosphere, can be measured in real-time, on location, without the need for laboratory analysis of samples.

  12. Determination of neutral carbon concentration in electron cyclotron resonance generated plasma discharges.

    PubMed

    Ene, A B; Lindner, P; Stirn, R; Schumacher, U

    2007-12-01

    Carbon containing plasmas play an important role not only in plasma technology but also in thermonuclear fusion research. In order to understand and control the processes taking place in the plasma, the knowledge of the carbon ground state density is of major importance. It can be determined by absorption and emission spectroscopy. Detailed measurements were performed in the past to determine the silicon ground state density by means of spectroscopy of the self-absorbed spectral lines of the silicon ground state multiplet at 251 nm. The same procedure was applied for the determination of the carbon concentration, for which the carbon multiplet at 165 nm was analyzed and compared to a simulated spectrum. The ground state density was determined by two independent methods. PMID:18163723

  13. Determination of neutral carbon concentration in electron cyclotron resonance generated plasma discharges

    SciTech Connect

    Ene, A. B.; Lindner, P.; Stirn, R.; Schumacher, U.

    2007-12-15

    Carbon containing plasmas play an important role not only in plasma technology but also in thermonuclear fusion research. In order to understand and control the processes taking place in the plasma, the knowledge of the carbon ground state density is of major importance. It can be determined by absorption and emission spectroscopy. Detailed measurements were performed in the past to determine the silicon ground state density by means of spectroscopy of the self-absorbed spectral lines of the silicon ground state multiplet at 251 nm. The same procedure was applied for the determination of the carbon concentration, for which the carbon multiplet at 165 nm was analyzed and compared to a simulated spectrum. The ground state density was determined by two independent methods.

  14. Position for determining gas-phase volatile organic compound concentrations in transuranic waste containers. Revision 2

    SciTech Connect

    Connolly, M.J.; Liekhus, K.J.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R.

    1998-06-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations.

  15. Position for determining gas phase volatile organic compound concentrations in transuranic waste containers. Revision 1

    SciTech Connect

    Connolly, M.J.; Liekhus, K.J.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R.

    1995-08-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering Laboratory (INEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations.

  16. Determination of type and concentration of DNA nitrogenous bases by Raman spectroscopy using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Laptinskiy, Kirill A.; Burikov, Sergey A.; Sarmanova, Olga E.; Dolenko, Sergey A.; Dolenko, Tatiana A.

    2016-04-01

    In this article the results of solution of two-parametrical inverse problems of laser Raman spectroscopy of identification and determination of concentration of DNA nitrogenous bases in two-component solutions are presented. Elaboration of methods of control of reactions with DNA strands in remote real-time mode is necessary for solution of one of the basic problems of creation of biocomputers - increase of reliability of molecular DNA-computations. The comparative analysis of two used methods of solution of stated problems has demonstrated convincing advantages of technique of artificial neural networks. Use of artificial neural networks allowed to reach the accuracy of determination of concentration of each base in two-component solutions 0.2-0.3 g/l.

  17. Determination of Sperm Concentration for Small-Bodied Biomedical Model Fishes by Use of Microspectrophotometry

    PubMed Central

    Tan, Ereene; Tiersch, Terrence R.

    2010-01-01

    Abstract The goal of this study was to establish an efficient method for determination of sperm concentration requiring only 1–2 μL of sample by use of microspectrophotometry. The objectives were (1) determination of wavelengths with absorbance profiles appropriate for analysis of sperm suspensions from zebrafish Danio rerio, green swordtail Xiphophorus helleri, and medaka Oryzias latipes collected by crushing of dissected testis or by stripping of live males; (2) generation of standard curves and equations between sperm sample absorbance and sperm concentration estimated by hemocytometer counts; (3) accuracy verification of equations for estimating concentration by microspectrophotometry; and (4) analysis of the precision in generating equations and estimation of sperm concentration. Within the visible wavelengths (380–750 nm) there was no single maximal absorbance peak. For zebrafish, a linear correlation was established with an effective absorbance range of 0.034–0.936 for crushed samples, and 0.028–0.961 for stripped samples at 400 nm. For Xiphophorus, the effective absorbance range was 0.014–1.154 for crushed samples, and the effective range was 0.038–1.082 for stripped samples. For medaka, the effective range was 0.041–0.896 for crushed samples. The accuracy of these equations was verified by comparison of sample concentrations counted with hemocytometer and calculated with equations, and no significant differences (p = 0.447) were observed. Measurement of serially diluted aliquots from pooled samples verified the precision of techniques used. Overall, this confirmed that microspectrophotometric estimation of sperm concentration is accurate, efficient, and sample-saving for use with small-bodied fishes. PMID:20515322

  18. A Photometric Technique for Determining Fluid Concentration using Consumer-Grade Hardware

    NASA Technical Reports Server (NTRS)

    Leslie, F.; Ramachandran, N.

    1999-01-01

    In support of a separate study to produce an exponential concentration gradient in a magnetic fluid, a noninvasive technique for determining, species concentration from off-the-shelf hardware has been developed. The approach uses a backlighted fluid test cell photographed with a commercial digital camcorder. Because the light extinction coefficient is wavelength dependent, tests were conducted to determine the best filter color to use, although some guidance was also provided using an absorption spectrophotometer. With the appropriate filter in place, the provide attenuation of the light passing, through the test cell was captured by the camcorder. The digital image was analyzed for intensity using, software from Scion Image Corp. downloaded from the Internet. The analysis provides a two-dimensional array of concentration with an average error of 0.0095 ml/ml. This technique is superior to invasive techniques, which require extraction of a sample that disturbs the concentration distribution in the test cell. Refinements of this technique using a true monochromatic laser light Source are also discussed.

  19. In vivo confocal Raman microspectroscopy of the skin: noninvasive determination of molecular concentration profiles.

    PubMed

    Caspers, P J; Lucassen, G W; Carter, E A; Bruining, H A; Puppels, G J

    2001-03-01

    Confocal Raman spectroscopy is introduced as a noninvasive in vivo optical method to measure molecular concentration profiles in the skin. It is shown how it can be applied to determine the water concentration in the stratum corneum as a function of distance to the skin surface, with a depth resolution of 5 microm. The resulting in vivo concentration profiles are in qualitative and quantitative agreement with published data, obtained by in vitro X-ray microanalysis of skin samples. Semi-quantitative concentration profiles were determined for the major constituents of natural moisturizing factor (serine, glycine, pyrrolidone-5-carboxylic acid, arginine, ornithine, citrulline, alanine, histidine, urocanic acid) and for the sweat constituents lactate and urea. A detailed description is given of the signal analysis methodology that enables the extraction of this information from the skin Raman spectra. No other noninvasive in vivo method exists that enables an analysis of skin molecular composition as a function of distance to the skin surface with similar detail and spatial resolution. Therefore, it may be expected that in vivo confocal Raman spectroscopy will find many applications in basic and applied dermatologic research. PMID:11231318

  20. Determining Source Strength of Semivolatile Organic Compounds using Measured Concentrations in Indoor Dust

    PubMed Central

    Shin, Hyeong-Moo; McKone, Thomas E.; Nishioka, Marcia G.; Fallin, M. Daniele; Croen, Lisa A.; Hertz-Picciotto, Irva; Newschaffer, Craig J.; Bennett, Deborah H.

    2014-01-01

    Consumer products and building materials emit a number of semivolatile organic compounds (SVOCs) in the indoor environment. Because indoor SVOCs accumulate in dust, we explore the use of dust to determine source strength and report here on analysis of dust samples collected in 30 U.S. homes for six phthalates, four personal care product ingredients, and five flame retardants. We then use a fugacity-based indoor mass-balance model to estimate the whole house emission rates of SVOCs that would account for the measured dust concentrations. Di-2-ethylhexyl phthalate (DEHP) and di-iso-nonyl phthalate (DiNP) were the most abundant compounds in these dust samples. On the other hand, the estimated emission rate of diethyl phthalate (DEP) is the largest among phthalates, although its dust concentration is over two orders of magnitude smaller than DEHP and DiNP. The magnitude of the estimated emission rate that corresponds to the measured dust concentration is found to be inversely correlated with the vapor pressure of the compound, indicating that dust concentrations alone cannot be used to determine which compounds have the greatest emission rates. The combined dust-assay modeling approach shows promise for estimating indoor emission rates for SVOCs. PMID:24118221

  1. Exploration of noninvasive determination of blood glucose concentration by using photoacoustic technique

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Liu, Ying; Huang, Zhen

    2013-09-01

    Photoacoustic (PA) noninvasive detection has become a research hotspot of measuring blood glucose concentration (BGC) in recent years. This novel method overcomes greatly the scattering light interference problem must be faced in near infrared (NIR) spectroscopy. A PA based BGC measurement set-up was established, in which a Q switched Nd: YAG pumped optical parametric oscillator (OPO) pulsed laser is used as the excitation source and lateral detection model was used to detetct the PA signals of glucose. To validate the profile model of real time PA signal, determine the characteristic wavelengths of glucose, a series of vitro experiments of glucose aqueous solutions were perfromed. Several wavelengths were preliminarily determined as the characteristic wavelengths via the peak-to-peak values difference. The prediction concentration model was established via least square fitting algorithm between PA peak-to-peak values with their different concentrations. The experimental results demonstrated that the PA profile of glucose is consistent with PA meachnism and the root-mean-squre error (RMSE) of prediction concentration can reach 0.77mmol/L. Therefore, this PA based set-up and scheme has the potential value in the BGC monitoring research.

  2. Determination of Heavy Metals Concentration in Traditional Herbs Commonly Consumed in the United Arab Emirates

    PubMed Central

    Dghaim, Rania; Al Khatib, Safa; Rasool, Husna; Ali Khan, Munawwar

    2015-01-01

    Herbs are extensively consumed in the United Arab Emirates for their flavoring and medicinal properties. This study aimed at determining the concentration of heavy metals in selected traditional herbs consumed in the United Arab Emirates (UAE). A total of 81 samples of seven herbs, parsley (Petroselinum crispum), basil (Ocimum basilicum), sage (Salvia officinalis), oregano (Origanum vulgare), mint (Mentha spicata), thyme (Thymus vulgaris), and chamomile (Matricaria chamomilla), were purchased from the local market in Dubai and analyzed for their cadmium, lead, copper, iron, and zinc contents. Microwave-assisted digestion was applied for the dissolution of the samples and heavy metals concentration was determined using Atomic Absorption Spectrometry (AAS). Metals were found to be present in varied concentrations in the herb samples. The concentration ranges were found as follows: less than 0.1–1.11 mg·kg−1 for cadmium, less than 1.0–23.52 mg·kg−1 for lead, 1.44–156.24 mg·kg−1 for copper, 12.65–146.67 mg·kg−1 for zinc, and 81.25–1101.22 mg·kg−1 for iron. The findings of the study suggest that most of the analyzed herbs contained unsafe levels of heavy metals that exceeded the World Health Organization (WHO) permissible limits (PL). PMID:26000023

  3. Determination of heavy metals concentration in traditional herbs commonly consumed in the United Arab Emirates.

    PubMed

    Dghaim, Rania; Al Khatib, Safa; Rasool, Husna; Ali Khan, Munawwar

    2015-01-01

    Herbs are extensively consumed in the United Arab Emirates for their flavoring and medicinal properties. This study aimed at determining the concentration of heavy metals in selected traditional herbs consumed in the United Arab Emirates (UAE). A total of 81 samples of seven herbs, parsley (Petroselinum crispum), basil (Ocimum basilicum), sage (Salvia officinalis), oregano (Origanum vulgare), mint (Mentha spicata), thyme (Thymus vulgaris), and chamomile (Matricaria chamomilla), were purchased from the local market in Dubai and analyzed for their cadmium, lead, copper, iron, and zinc contents. Microwave-assisted digestion was applied for the dissolution of the samples and heavy metals concentration was determined using Atomic Absorption Spectrometry (AAS). Metals were found to be present in varied concentrations in the herb samples. The concentration ranges were found as follows: less than 0.1-1.11 mg·kg(-1) for cadmium, less than 1.0-23.52 mg·kg(-1) for lead, 1.44-156.24 mg·kg(-1) for copper, 12.65-146.67 mg·kg(-1) for zinc, and 81.25-1101.22 mg·kg(-1) for iron. The findings of the study suggest that most of the analyzed herbs contained unsafe levels of heavy metals that exceeded the World Health Organization (WHO) permissible limits (PL). PMID:26000023

  4. Absolute isotopic abundances of TI in meteorites

    NASA Astrophysics Data System (ADS)

    Niederer, F. R.; Papanastassiou, D. A.; Wasserburg, G. J.

    1985-03-01

    The absolute isotope abundance of Ti has been determined in Ca-Al-rich inclusions from the Allende and Leoville meteorites and in samples of whole meteorites. The absolute Ti isotope abundances differ by a significant mass dependent isotope fractionation transformation from the previously reported abundances, which were normalized for fractionation using 46Ti/48Ti. Therefore, the absolute compositions define distinct nucleosynthetic components from those previously identified or reflect the existence of significant mass dependent isotope fractionation in nature. The authors provide a general formalism for determining the possible isotope compositions of the exotic Ti from the measured composition, for different values of isotope fractionation in nature and for different mixing ratios of the exotic and normal components.

  5. Evaluation of analytical techniques to determine AQUI-S(R) 20E (eugenol) concentrations in water

    USGS Publications Warehouse

    Meinertz, Jeffery R.; Hess, Karina R.

    2013-01-01

    There is a critical need in U.S. public aquaculture and fishery management programs for an immediate-release sedative, i.e. a compound that can be safely and effectively used to sedate fish and subsequently, allow for their immediate release. AQUI-S® 20E (10% active ingredient, eugenol; any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government) is being pursued for U.S. approval as an immediate-release sedative. As part of the approval process, data describing animal safety and efficacy are needed. Essential to conducting studies that generate those data, is a method to accurately and precisely determine AQUI-S® 20E concentrations in exposure baths. Spectrophotometric and solid phase extraction (SPE)–high pressure liquid chromatography (LC) methods were developed and evaluated as methods to determine AQUI-S® 20E (eugenol) concentrations in water, methods that could be applied to any situation where eugenol was being evaluated as a fish sedative. The spectrophotometric method was accurate and precise (accuracy, > 87%; precision, < 0.70 %CV) when determining eugenol concentrations in solutions of 50 to 1000 mg/L AQUI-S® 20E made with LC grade water and water with varying pH and hardness. The spectrophotometric method's accuracy was negatively affected when analyzing water containing fish feed. The SPE–LC method was also accurate and precise (accuracy > 86%; precision < 8.9 %CV) when determining eugenol concentrations in solutions of 50 to 1000 mg/L AQUI-S® 20E made with LC grade water and water with varying pH and hardness. The SPE–LC method was influenced to a lesser degree by the presence of fish feed indicating greater specificity for eugenol.

  6. New directional results and determination of absolute archaeointensity using both the classical Thellier and the multi-specimen procedures for two kilns excavated at Osterietta, Italy

    NASA Astrophysics Data System (ADS)

    Tema, Evdokia; Camps, Pierre; Ferrara, Enzo

    2014-05-01

    A detailed rock-magnetic and archaeomagnetic study has been carried out on two rescue excavation kilns discovered during the works to expand a highway at the location of Osterietta, in Northen Italy. Systematic archaeomagnetic sampling was carried out collecting 15 samples from the first kiln (OSA) and 8 samples from the second kiln (OSB), all of them oriented in situ with a magnetic compass and an inclinometer. Magnetic mineralogy measurements have been carried out in order to determine the main magnetic carrier of the samples and to check their thermal stability. Standard thermal demagnetization procedures have been used to determine the archaeomagnetic direction registered by the bricks during their last firing. Demagnetization results show a very stable characteristic remanent magnetization (ChRM). We averaged the directions for each kiln separately and calculated the statistical parameters assuming a Fisherian distribution. The archaeointensity of both kilns has also been recovered with both the classical Thellier-Thellier method and the multi-specimen procedure (MSP-DSC). During the Thellier experiments, regular partial thermoremanent magnetization checks have been performed and the effect of the anisotropy of the thermoremanent magnetization (TRM) and cooling rate upon TRM intensity acquisition have been investigated in all samples. The multi-specimen procedure was performed with a very fast-heating oven developed at Montpellier (France). The intensity results obtained from both methods have been compared and the full geomagnetic field vector determined for each kiln has been used for archaeomagnetic dating. The obtained results show that the kilns were almost contemporaneous and their last use occurred in the 1750-1850 AD time interval.

  7. Evaluation of analytical techniques to determine AQUI-S® 20E (eugenol) concentrations in water

    USGS Publications Warehouse

    Meinertz, Jeffery R.; Hess, Karina R.

    2014-01-01

    There is a critical need in U.S. public aquaculture and fishery management programs for an immediate-release sedative, i.e. a compound that can be safely and effectively used to sedate fish and subsequently, allow for their immediate release. AQUI-S® 20E (10% active ingredient, eugenol; any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government) is being pursued for U.S. approval as an immediate-release sedative. As part of the approval process, data describing animal safety and efficacy are needed. Essential to conducting studies that generate those data, is a method to accurately and precisely determine AQUI-S® 20E concentrations in exposure baths. Spectrophotometric and solid phase extraction (SPE)–high pressure liquid chromatography (LC) methods were developed and evaluated as methods to determine AQUI-S® 20E (eugenol) concentrations in water, methods that could be applied to any situation where eugenol was being evaluated as a fish sedative. The spectrophotometric method was accurate and precise (accuracy, > 87%; precision, 86%; precision < 8.9 %CV) when determining eugenol concentrations in solutions of 50 to 1000 mg/L AQUI-S® 20E made with LC grade water and water with varying pH and hardness. The SPE–LC method was influenced to a lesser degree by the presence of fish feed indicating greater specificity for eugenol.

  8. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A.; Belasri, A.

    2015-09-01

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C CF-LIBS calculated by CF-LIBS and the certified concentrations C certified were very close.

  9. Assessment of relative accuracy in the determination of organic matter concentrations in aquatic systems

    USGS Publications Warehouse

    Aiken, G.; Kaplan, L.A.; Weishaar, J.

    2002-01-01

    Accurate determinations of total (TOC), dissolved (DOC) and particulate (POC) organic carbon concentrations are critical for understanding the geochemical, environmental, and ecological roles of aquatic organic matter. Of particular significance for the drinking water industry, TOC measurements are the basis for compliance with US EPA regulations. The results of an interlaboratory comparison designed to identify problems associated with the determination of organic matter concentrations in drinking water supplies are presented. The study involved 31 laboratories and a variety of commercially available analytical instruments. All participating laboratories performed well on samples of potassium hydrogen phthalate (KHP), a compound commonly used as a standard in carbon analysis. However, problems associated with the oxidation of difficult to oxidize compounds, such as dodecylbenzene sulfonic acid and caffeine, were noted. Humic substances posed fewer problems for analysts. Particulate organic matter (POM) in the form of polystyrene beads, freeze-dried bacteria and pulverized leaf material were the most difficult for all analysts, with a wide range of performances reported. The POM results indicate that the methods surveyed in this study are inappropriate for the accurate determination of POC and TOC concentration. Finally, several analysts had difficulty in efficiently separating inorganic carbon from KHP solutions, thereby biasing DOC results.

  10. Poverty concentration and determinants in China's urban low-income neighbourhoods and social groups.

    PubMed

    He, Shenjing; Wu, Fulong; Webster, Chris; Liu, Yuting

    2010-01-01

    Based on a large-scale household survey conducted in 2007, this article reports on poverty concentration and determinants in China's low-income neighbourhoods and social groups. Three types of neighbourhood are recognized: dilapidated inner-city neighbourhoods, declining workers' villages and urban villages. Respondents are grouped into four categories: working, laid-off/unemployed and retired urban residents, together with rural migrants. We first measure poverty concentration across different types of neighbourhood and different groups. The highest concentrations are found in dilapidated inner-city neighbourhoods and among the laid-off/unemployed. Mismatches are found between actual hardships, sense of deprivation and distribution of social welfare provision. Second, we examine poverty determinants. Variations in institutional protection and market remuneration are becoming equally important in predicting poverty generation, but are differently associated with it in the different neighbourhoods and groups. As China's urban economy is increasingly shaped by markets, the mechanism of market remuneration is becoming a more important determinant of poverty patterns, especially for people who are excluded from state institutions, notably laid-off workers and rural migrants. PMID:20726146

  11. Determination of a brass alloy concentration composition using calibration-free laser-induced breakdown spectroscopy

    SciTech Connect

    Achouri, M.; Baba-Hamed, T.; Beldjilali, S. A. Belasri, A.

    2015-09-15

    Laser-induced breakdown spectroscopy (LIBS) is a technique that can provide qualitative and quantitative measurements of the characteristics of irradiated metals. In the present work, we have calculated the parameters of the plasma produced from a brass alloy sample under the action of a pulsed Nd: YAG laser operating at 1064 nm. The emission lines of copper atoms (Cu I), zinc atoms (Zn I), and lead atoms (Pb I), which are elements of a brass alloy composition, were used to investigate the parameters of the brass plasma. The spectral profiles of Cu, Zn, and Pb lines have been used to extract the electron temperature and density of the brass alloy plasma. The characteristics of Cu, Zn, and Pb were determined quantatively by the calibration-free LIBS (CF-LIBS) method considering for accurate analysis that the laser-induced ablated plasma is optically thin in local thermodynamic equilibrium conditions and the plasma ablation is stoichiometric. The Boltzmann plot method was used to evaluate the plasma temperature, and the Stark broadened profiles were used to determine the electron density. An algorithm based on the experimentally measured values of the intensity of spectral lines and the basic laws of plasma physics was developed for the determination of Cu, Zn, and Pb concentrations in the brass sample. The concentrations C{sub CF-LIBS} calculated by CF-LIBS and the certified concentrations C{sub certified} were very close.

  12. Sperm concentration determination between hemacytometric and CASA systems: why they can be different.

    PubMed

    Kuster, Chris

    2005-08-01

    Determination of sperm concentration is a critical component of semen analysis. Traditionally, the hemacytometer has been the standard for calibrating other technologies used to estimate sperm concentration, including photometry, Coulter counters, flow cytometry, and computer-automated semen analysis (CASA). Disposable capillary-loaded slides are commonly used in conjunction with most CASA systems currently in use. Questions have been raised regarding differences in sperm concentration measurements between CASA systems (using 20 microm disposable slides) and hemacytometry. This review explains that these differences are largely due to the Segre-Silberberg (SS) effect, which occurs during Poiseuille flow in thin, capillary-loaded slides. The SS effect can lead to errors in estimation of particle concentration, as demonstrated with latex beads and suspensions of human or porcine spermatozoa. The SS effect does not appear to have time to develop in the hemacytometer, which at 100 microm is considerably deeper than most disposable slides. Thus, hemacytometry, when properly performed, remains the gold standard for estimation of sperm concentration. When using thin (20 microm) slides with CASA systems, recognition of the appropriate compensation factor to adjust for the SS effect is critical for accuracy. PMID:16002129

  13. Determinants of spikes in ultrafine particle concentration whilst commuting by bus

    NASA Astrophysics Data System (ADS)

    Lim, Shanon; Dirks, Kim N.; Salmond, Jennifer A.; Xie, Shanju

    2015-07-01

    This paper examines concentration of ultrafine particles (UFPs) based on data collected using high-resolution UFP monitors whilst travelling by bus during rush hour along three different urban routes in Auckland, New Zealand. The factors influencing in-bus UFP concentration were assessed using a combination of spatial, statistical and GIS analysis techniques to determine both spatial and temporal variability. Results from 68 bus trips showed that concentrations varied more within a route than between on a given day, despite differences in urban morphology, land use and traffic densities between routes. A number of trips were characterised by periods of very rapid increases in UFPs (concentration 'spikes'), followed by slow declines. Trips which recorded at least one spike (an increase of greater than 10,000 pt/cm3) resulted in significantly higher mean concentrations. Spikes in UFPs were significantly more likely to occur when travelling at low speeds and when passengers were alighting and boarding at bus stops close to traffic light intersections.

  14. Sodium chloride concentration determines exoelectrogens in anode biofilms occurring from mangrove-grown brackish sediment.

    PubMed

    Miyahara, Morio; Kouzuma, Atsushi; Watanabe, Kazuya

    2016-10-01

    Single-chamber microbial fuel cells (MFCs) were inoculated with mangrove-grown brackish sediment (MBS) and continuously supplied with an acetate medium containing different concentrations of NaCl (0-1.8M). Different from MFCs inoculated with paddy-field soil (high power outputs were observed between 0.05 and 0.1M), power outputs from MBS-MFCs were high at NaCl concentrations from 0 to 0.6M. Amplicon-sequence analyses of anode biofilms suggest that different exoelectrogens occurred from MBS depending on NaCl concentrations; Geobacter occurred abundantly below 0.1M, whereas Desulfuromonas was abundant from 0.3M to 0.6M. These results suggest that NaCl concentration is the major determinant of exoelectrogens that occur in anode biofilms from MBS. It is also suggested that MBS is a potent source of microbes for MFCs to be operated in a wide range of NaCl concentrations. PMID:27420153

  15. Emission Controls Versus Meteorological Conditions in Determining Aerosol Concentrations in Beijing during the 2008 Olympic Games

    SciTech Connect

    Gao, Yi; Liu, Xiaohong; Zhao, Chun; Zhang, Meigen

    2011-12-12

    A series of emission control measures were undertaken in Beijing and the adjacent provinces in China during the 2008 Beijing Olympic Games on August 8th-24th, 2008. This provides a unique opportunity for investigating the effectiveness of emission controls on air pollution in Beijing. We conducted a series of numerical experiments over East Asia for the period of July to September 2008 using a coupled meteorology-chemistry model (WRF-Chem). Model can generally reproduce the observed variation of aerosol concentrations. Consistent with observations, modeled concentrations of aerosol species (sulfate, nitrate, ammonium, black carbon, organic carbon, total particulate matter) in Beijing were decreased by 30-50% during the Olympic period compared to the other periods in July and August in 2008 and the same period in 2007. Model results indicate that emission controls were effective in reducing the aerosol concentrations by comparing simulations with and without emission controls. However, our analysis suggests that meteorological conditions (e.g., wind direction and precipitation) are at least as important as emission controls in producing the low aerosol concentrations appearing during the Olympic period. Transport from the regions surrounding Beijing determines the temporal variation of aerosol concentrations in Beijing. Based on the budget analysis, we suggest that emission control strategy should focus on the regional scale instead of the local scale to improve the air quality over Beijing.

  16. Chromatographic determination of nanomolar cyanate concentrations in estuarine and sea waters by precolumn fluorescence derivatization.

    PubMed

    Widner, Brittany; Mulholland, Margaret R; Mopper, Kenneth

    2013-07-16

    Recent studies suggest that cyanate (OCN(-)) is a potentially important source of reduced nitrogen (N) available to support the growth of aquatic microbes and, thus, may play a role in aquatic N cycling. However, aquatic OCN(-) distributions have not been previously described because of the lack of a suitable assay for measuring OCN(-) concentrations in natural waters. Previous methods were designed to quantify OCN(-) in aqueous samples with much higher reduced N concentrations (micromolar levels) than those likely to be found in natural waters (nanomolar levels). We have developed a method to quantify OCN(-) in dilute, saline environments. In the method described here, OCN(-) in aqueous solution reacts with 2-aminobenzoic acid to produce a highly fluorescent derivative, 2,4-quinazolinedione, which is then quantified using high performance liquid chromatography. Derivatization conditions were optimized to simultaneously minimize the reagent blank and maximize 2,4-quinazolinedione formation (>90% reaction yield) in estuarine and seawater matrices. A limit of detection (LOD) of 0.4 nM was achieved with only minor matrix effects. We applied this method to measure OCN(-) concentrations in estuarine and seawater samples from the Chesapeake Bay and coastal waters from the mid-Atlantic region. OCN(-) concentrations ranged from 0.9 to 41 nM. We determined that OCN(-) concentrations were stable in 0.2 μm filtered seawater samples stored at -80 °C for up to nine months. PMID:23738747

  17. Determination of concentration of charged particles in various regions of thunderstorms

    NASA Astrophysics Data System (ADS)

    Detwiler, A. G.; Mo, Q.

    2015-12-01

    During the Severe Thunderstorm Precipitation and Electrification Study in 2000, data on hydrometeor sizes and charges were obtained in thunderstorms using an optical array probe modified by the New Mexico Institute of Mining and Technology and mounted on the South Dakota School of Mines and Technology armored T-28 research aircraft. Analysis yielded quantitative observations of hydrometeor size and charge data in selected regions of storms with relatively low concentrations of charged particles. In most regions hydrometeor concentrations were so high that there were multiple charged particles in the probe sample volume at the same time and quantitative charge analysis was not possible. While it is impossible to reliably determine individual particle charges in these high concentration regions, we can use Poisson statistics to estimate the total number concentration of charged particles based on the fraction of records with just one particle in them. We compare these number concentrations for different thunderstorm regions, including updrafts, flanking cells, core precipitation regions, and trailing stratiform regions, at approximately the -10 C level, in several thunderstorms. We will discuss the implications of these results for understanding charge-separation processes in thunderstorms.

  18. Emission controls versus meteorological conditions in determining aerosol concentrations in Beijing during the 2008 Olympic Games

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Liu, X.; Zhao, C.; Zhang, M.

    2011-12-01

    A series of emission control measures were undertaken in Beijing and the adjacent provinces in China during the 2008 Beijing Olympic Games on 8-24 August 2008. This provides a unique opportunity for investigating the effectiveness of emission controls on air pollution in Beijing. We conducted a series of numerical experiments over East Asia for the period of July to September 2008 using a coupled meteorology-chemistry model (WRF-Chem). Model can generally reproduce the observed variation of aerosol concentrations. Consistent with observations, modeled concentrations of aerosol species (sulfate, nitrate, ammonium, black carbon, organic carbon, total particulate matter) in Beijing were decreased by 30-50% during the Olympic period compared to the other periods in July and August in 2008 and the same period in 2007. Model results indicate that emission controls were effective in reducing the aerosol concentrations by comparing simulations with and without emission controls. In addition to emission controls, our analysis suggests that meteorological conditions (e.g. wind direction and precipitation) were also important in producing the low aerosol concentrations appearing during the Olympic period. Transport from the regions surrounding Beijing determined the daily variation of aerosol concentrations in Beijing. Based on the budget analysis, we suggest that to improve the air quality over Beijing, emission control strategy should focus on the regional scale instead of the local scale.

  19. Critical factors determining fluoride concentration in tea leaves produced from Anhui province, China.

    PubMed

    Cai, Huimei; Zhu, Xiaohui; Peng, Chuanyi; Xu, Wei; Li, Daxiang; Wang, Yijun; Fang, Shihui; Li, Yeyun; Hu, Shaode; Wan, Xiaochun

    2016-09-01

    This study investigated the fluoride present in tea plants (Camellia sinensis (L.) O. Kuntze) and its relationship to soils, varieties, seasons and tea leaf maturity. The study also explored how different manufacturing processes affect the leaching of fluoride into tea beverages. The fluoride concentration in the tea leaves was significantly correlate to the concentration of water-soluble fluoride in the soil. Different tea varieties accumulated different levels of fluoride, with varieties, Anji baicha having the highest and Nongkang zao having the lowest fluoride concentration. In eight different varieties of tea plant harvested over three tea seasons, fluoride concentration were highest in the summer and lowest in the spring in china. The fluoride concentration in tea leaves was directly related to the maturity of the tea leaves at harvest. Importantly, the tea manufacturing process did not introduced fluoride contamination. The leaching of fluoride was 6.8% and 14.1% higher in black and white tea, respectively, than in fresh tea leaves. The manufacturing step most affecting the leaching of fluoride into tea beverage was withering used in white, black and oolong tea rather than rolling or fermentation. The exposure and associated health risks for fluoride concentration in infusions of 115 commercially available teas from Chinese tea markets was determined. The fluoride concentration ranged from 5.0 to 306.0mgkg(-1), with an average of 81.7mgkg(-1). The hazard quotient (HQ) of these teas indicated that there was no risk of fluorosis from drinking tea, based on statistical analysis by Monte Carlo simulation. PMID:27162130

  20. Determining concentration and fall velocity of estuarine particle populations using ADV, OBS and LISST

    NASA Astrophysics Data System (ADS)

    Fugate, David C.; Friedrichs, Carl T.

    2002-07-01

    In describing suspended sediment conditions in the lower Chesapeake Bay, VA, USA, this paper reports and develops methods for distinguishing multiple particle populations in the bottom boundary layer of estuaries in general. In addition, a novel application of the acoustic Doppler velocimeter (ADV) is shown to estimate in situ particle fall velocity at a single point without affecting the ambient turbulence. In situ estimates of suspended sediment concentration from ADV, optical backscatter, and laser in situ scattering and transmissometry (LISST) instruments are compared with gravimetrically determined mass concentrations from pumped water samples. In this environment, acoustic backscatter from the ADV proved to be the best estimator of mass concentrations due to its apparent insensitivity to the size or density of muddy aggregates. The concentration estimates and the relative sensitivities of the instruments to particle size and density combined with size distribution information from the LISST reveal the characteristics of multiple particle populations in the bottom boundary layer. Two rapidly settling sediment populations are suggested with similar fall velocities but distinct critical erosion stresses. A slowly settling background population is also identified whose concentration varies over meteorological time scales. Fall velocities are estimated analytically from a balance of settling and diffusive flux gradients using two methods, one employing Reynolds concentration flux, and the other estimating eddy diffusivity using the von-Karman Prandtl equation. Comparison of the local change and advective terms in the solute transport equation to the magnitude of the settling term suggests that a balance between the settling and resuspension term is a good first order approximation at this site, validating the indirect method for estimating settling velocity. Single elevation estimates of fall velocity using the ADV to estimate Reynolds concentration flux produced

  1. Determinants of personal, indoor and outdoor VOC concentrations: An analysis of the RIOPA data

    PubMed Central

    Su, Feng-Chiao; Mukherjee, Bhramar; Batterman, Stuart

    2014-01-01

    Community and environmental exposure to volatile organic compounds (VOCs) has been associated with a number of emission sources and activities, e.g., environmental tobacco smoke and pumping gasoline. Such factors have been identified from mostly small studies with relatively limited information regarding influences on VOC levels. This study uses data from the Relationship of Indoor Outdoor and Personal Air (RIOPA) study to investigate environmental, individual and social determinants of VOC concentrations. RIOPA included outdoor, indoor and personal measurements of 18 VOCs from 310 non-smoking households and adults in three cities and two seasons, and collected a wide range of information pertaining to participants, family members, households, and neighborhoods. Exposure determinants were identified using stepwise regressions and linear mixed-effect models. Most VOC exposure (66 to 78% of the total exposure, depending on VOC) occurred indoors, and outdoor VOC sources accounted for 5 (d-limonene) to 81% (carbon tetrachloride) of the total exposure. Personal exposure and indoor measurements had similar determinants, which depended on the VOC. Gasoline-related VOCs (e.g., benzene, methyl tertiary butyl ether) were associated with city, residences with attached garages, self-pumping of gas, wind speed, and house air exchange rate (AER). Odorant and cleaning-related VOCs (e.g., 1,4-dichlorobenzene and chloroform) also were associated with city and AER, and with house size and family members showering. Dry-cleaning and industry-related VOCs (e.g., tetrachloroethylene and trichloroethylene) were associated with city, residence water supply type, and dry-cleaner visits. These and other relationships were significant, explained from 10 to 40% of the variation, and are consistent with known emission sources and the literature. Outdoor concentrations had only two common determinants: city and wind speed. Overall, personal exposure was dominated by the home setting, although a

  2. The equilibrium constant for N2O5 = NO2 + NO3 - Absolute determination by direct measurement from 243 to 397 K

    NASA Technical Reports Server (NTRS)

    Cantrell, C. A.; Davidson, J. A.; Mcdaniel, A. H.; Shetter, R. E.; Calvert, J. G.

    1988-01-01

    Direct determinations of the equilibrium constant for the reaction N2O5 = NO2 + NO3 were carried out by measuring NO2, NO3, and N2O5 using long-path visible and infrared absorption spectroscopy as a function of temperature from 243 to 397 K. The first-order decay rate constant of N2O5 was experimentally measured as a function of temperature. These results are in turn used to derive a value for the rate coefficient for the NO-forming channel in the reaction of NO3 with NO2. The implications of the results for atmospheric chemistry, the thermodynamics of NO3, and for laboratory kinetics studies are discussed.

  3. Combined Absolute/Relative Hypocenter Determination and Moment Tensor Inversion of a VT-B Event Cluster Before the 1998 Eruption of the Mt. Merapi Volcano (Java)

    NASA Astrophysics Data System (ADS)

    Wassermann, J.; Krüger, F.

    2001-12-01

    In the ongoing Indonesian-German MERAPI project the seismic signals at Merapi volcano are recorded continuously since July 1997 with a combined seismic network-array approach. With this network it was possible to record the seismicity before the onset of the eruption in July 1998 with a high dynamic and broad frequency range. The automatic standard analysis of the recorded seismic data before the first of two larger pyroclastic density flows emphasized the importance of a seismic swarm of VT-B type events in order to forecast the location of the newly formed lava lobe during this eruptive phase. To improve the location accuracy, we relocate these events using an extended cluster analysis technique. We first estimate the amount of events in three different seismic clusters. After this we estimate the relative onset times of all event combinations within one cluster using the SmoothedCOherencyTransform algorithm. Further we use the amplitude of the computed cross-correlation coefficients of each event-event waveform pair to further restrict our hypocenter constrain. In the final step we invert iteratively all estimated travel times, the relative travel times within the different arrays and the correlation coefficients in one single matrix. The resulting high precision hypocenter determination of the distinct clusters indicate a small source volume in the intersection of a old crater floor and the active part of Mt. Merapi. The high precision in hypocenter determination make a detailed analysis of the source mechanisms of these VTB events feasible. We use a point source full moment tensor inversion and simple source time functions to invert for the source mechanism. Greens functions are calculated with the reflectivity method and local 1D models based on refraction on different scales. The bias in the results due to not modelled topography and 3D-structure is estimated using a bootstrap approach.

  4. Optical and probe determination of soot concentrations in a model gas turbine combustor

    NASA Technical Reports Server (NTRS)

    Eckerle, W. A.; Rosfjord, T. J.

    1986-01-01

    An experimental program was conducted to track the variation in soot loading in a generic gas turbine combustor. The burner is a 12.7-cm dia cylindrical device consisting of six sheet-metal louvers. Determination of soot loading along the burner length is achieved by measurement at the exit of the combustor and then at upstream stations by sequential removal of liner louvers to shorten burner length. Alteration of the flow field approaching and within the shortened burners is minimized by bypassing flow in order to maintain a constant linear pressure drop. The burner exhaust flow is sampled at the burner centerline to determine soot mass concentration and smoke number. Characteristic particle size and number density, transmissivity of the exhaust flow, and local radiation from luminous soot particles in the exhaust are determined by optical techniques. Four test fuels are burned at three fuel-air ratios to determine fuel chemical property and flow temperature influences. Particulate concentration data indicate a strong oxidation mechanism in the combustor secondary zone, though the oxidation is significantly affected by flow temperature. Soot production is directly related to fuel smoke point.

  5. Determination of colloidal gold nanoparticle surface areas, concentrations, and sizes through quantitative ligand adsorption.

    PubMed

    Gadogbe, Manuel; Ansar, Siyam M; He, Guoliang; Collier, Willard E; Rodriguez, Jose; Liu, Dong; Chu, I-Wei; Zhang, Dongmao

    2013-01-01

    Determination of the true surface areas, concentrations, and particle sizes of gold nanoparticles (AuNPs) is a challenging issue due to the nanoparticle morphological irregularity, surface roughness, and size distributions. A ligand adsorption-based technique for determining AuNP surface areas in solution is reported. Using a water-soluble, stable, and highly UV-vis active organothiol, 2-mercaptobenzimidazole (MBI), as the probe ligand, we demonstrated that the amount of ligand adsorbed is proportional to the AuNP surface area. The equivalent spherical AuNP sizes and concentrations were determined by combining the MBI adsorption measurement with Au(3+) quantification of aqua regia-digested AuNPs. The experimental results from the MBI adsorption method for a series of commercial colloidal AuNPs with nominal diameters of 10, 30, 50, and 90 nm were compared with those determined using dynamic light scattering, transmission electron microscopy, and localized surface plasmonic resonance methods. The ligand adsorption-based technique is highly reproducible and simple to implement. It only requires a UV-vis spectrophotometer for characterization of in-house-prepared AuNPs. PMID:23092965

  6. Ground-water sampling and time-series evaluation techniques to determine vertical concentration distributions

    SciTech Connect

    Cosler, D.J.

    1997-09-01

    Data analysis methodologies are developed for using time-series measurements of effluent concentrations during continuous sampling to determine the vertical shape and location of a horizontally uniform contaminant plume and to estimate physical/chemical aquifer parameters such as vertical anisotropy, effective porosity, and retardation factor. Temporal water-quality variations during constant-flow sampling are calculated in the form of concentration type curves for a wide variety of plume shapes and positions and are shown to be directly related to the geometry and growth rate of the three-dimensional capture volume of the well. An analytical type-curve solution is derived for discrete-interval sampling in homogeneous and isotropic/anisotropic aquifers containing plumes with complex vertical shapes that are described by the superposition of multiple Gaussian distributions. Results from two-dimensional, axisymmetric simulations of ground-water flow and particle transport demonstrate the sensitivity of concentration type curves to sandpack hydraulic conductivity, screen length, well diameter, flow through the well screen during discrete-interval sampling, aquifer anisotropy and heterogeneities, pumping rate, effective porosity, and chemical retardation. Two applications of the concentration type-curve method for determining plume and aquifer characteristics are presented. The first illustrates the use of discrete-interval sampling to evaluate the vertical shape and location of a hypothetical plume in a homogeneous, isotropic aquifer. In the second, extraction-well effluent data collected during a field experiment were used to evaluate the vertical concentration distribution in a sulfate plume and estimate the vertical anisotropy ratio of the aquifer. The results demonstrate the importance of developing consistency in purge and sample volumes to minimize artificial measurement variability in monitoring programs.

  7. Position for determining gas phase volatile organic compound concentrations in transuranic waste containers

    SciTech Connect

    Connolly, M.J.; Liekhus, K.J.; Djordjevic, S.M.; Loehr, C.A. Spangler, L.R.

    1995-12-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. The EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is unnecessary. A test program was conducted to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative.

  8. Accurate absolute frequencies of the {nu}{sub 1}+{nu}{sub 3} band of {sup 13}C{sub 2}H{sub 2} determined using an infrared mode-locked Cr:YAG laser frequency comb

    SciTech Connect

    Madej, Alan A.; Bernard, John E.; John Alcock, A.; Czajkowski, Andrzej; Chepurov, Sergei

    2006-04-15

    Absolute frequency measurements, with up to 1x10{sup -11} level accuracies, are presented for 60 lines of the P and R branches for the {nu}{sub 1}+{nu}{sub 3} band of {sup 13}C{sub 2}H{sub 2} at 1.5 {mu}m (194 THz). The measurements were made using cavity-enhanced, diode-laser-based saturation spectroscopy. With one laser system stabilized to the P(16) line and a second laser system stabilized to the line whose frequency was to be determined, a Cr:YAG frequency comb was employed to accurately measure the tetrahertz level frequency intervals. The results are compared with recent work from other groups and indicate that these lines would form a basis for a high-quality atlas of reference frequencies for this region of the spectrum.

  9. Accurate absolute reference frequencies from 1511 to 1545 nm of the {nu}{sub 1}+{nu}{sub 3} band of {sup 12}C{sub 2}H{sub 2} determined with laser frequency comb interval measurements

    SciTech Connect

    Madej, Alan A.; Alcock, A. John; Czajkowski, Andrzej; Bernard, John E.; Chepurov, Sergei

    2006-10-15

    Absolute frequency measurements, with uncertainties as low as 2 kHz (1x10{sup -11}), are presented for the {nu}{sub 1}+{nu}{sub 3} band of {sup 12}C{sub 2}H{sub 2} at 1.5 {mu}m (194-198 THz). The measurements were made using cavity-enhanced, diode-laser-based saturation spectroscopy. With one laser system stabilized to the P(16) line of {sup 13}C{sub 2}H{sub 2} and a system stabilized to the line in {sup 12}C{sub 2}H{sub 2} whose frequency was to be determined, a Cr:YAG laser-based frequency comb was employed to measure the frequency intervals. The systematic uncertainty is notably reduced relative to that of previous studies, and the region of measured lines has been extended. Improved molecular constants are obtained.

  10. Photometric and spectrochemical determination of gold in iron pyrites, copper and lead concentrates.

    PubMed

    Jordanov, N; Mareva, S; Krasnobaeva, N; Nedyalkova, N

    1968-09-01

    A photometric and a spectrochemical method have been developed for determining gold in iron pyrites, copper and lead concentrates. In both, the sample is dissolved and gold is extracted from 1M hydrochloric add solution with a mixture of ethyl methyl ketone and chloroform (1:1). Gold was determined photometrically with N,N'-tetramethyl-o-tolidine. Conditions have been found for satisfactorily sensitive and reproducible spectral determination of gold. For this purpose the effect of various collectors and buffers on the evaporation curves of gold has been studied, as well as excitation conditions, form of the electrodes, optimum slit-width, and photographic variables. The sensitivity and precision of both methods have been evaluated. PMID:18960389

  11. Absolute molecular weight determination of hypromellose acetate succinate by size exclusion chromatography: use of a multi angle laser light scattering detector and a mixed solvent.

    PubMed

    Chen, Raymond; Ilasi, Nicholas; Sekulic, Sonja S

    2011-12-01

    Molecular weight distribution is an important quality attribute for hypromellose acetate succinate (HPMCAS), a pharmaceutical excipient used in spray-dried dispersions. Our previous study showed that neither relative nor universal calibration method of size exclusion chromatography (SEC) works for HPMCAS polymers. We here report our effort to develop a SEC method using a mass sensitive multi angle laser light scattering detector (MALLS) to determine molecular weight distributions of HPMCAS polymers. A solvent screen study reveals that a mixed solvent (60:40%, v/v 50mM NaH(2)PO(4) with 0.1M NaNO(3) buffer: acetonitrile, pH* 8.0) is the best for HPMCAS-LF and MF sub-classes. Use of a mixed solvent creates a challenging condition for the method that uses refractive index detector. Therefore, we thoroughly evaluated the method performance and robustness. The mean weight average molecular weight of a polyethylene oxide standard has a 95% confidence interval of (28,443-28,793) g/mol vs. 28,700g/mol from the Certificate of Analysis. The relative standard deviations of average molecular weights for all polymers are 3-6%. These results and the Design of Experiments study demonstrate that the method is accurate and robust. PMID:21840663

  12. Determination of trace cobalt concentrations in human serum by adsorptive stripping voltammetry.

    PubMed

    Kajic, Petra; Milosev, Ingrid; Pihlar, Boris; Pisot, Venceslav

    2003-01-01

    The goal of our study was to develop an accurate and reliable method for determining trace cobalt concentrations in human serum. The method was used to determine cobalt in the sera of healthy persons and patients with orthopaedic implants containing cobalt - a possible source of systemic release of cobalt into the human body. This goal is of vital interest since cobalt and its compounds are classified by IARC as potentially carcinogenic to humans. We used an electrochemical method, adsorptive stripping voltammetry (AdSV), which made possible the low detection limit and high sensitivity needed for measurements in human serum. The serum was acid digested by a combination of H2SO4, HNO3 and H2O2 in a 10 mL Kjeldhal flask. The digested sample was then dissolved in 0.1 mol/L ammonia buffer, pH 9.0 +/- 0.2. The determination is based on the adsorptive collection of the complex of cobalt (II) with dimethylglyoxime on a hanging mercury drop electrode (HMDE). The optimum values of adsorption potential and time were determined to be -0.8 V and 60 s. The optimisation of the sample digestion protocol and measurement procedures ensured the reliable assessment of low cobalt concentrations, down to 0.03 microg/L. The mean concentration of serum cobalt in four healthy persons was 0.11 +/- 0.06 microg/L, and in four patients with total hip replacements 0.34 +/- 0.07 microg/L. This method will be used routinely for measuring serum cobalt levels in patients with total hip replacements. PMID:14968926

  13. Absolute Efficiency Calibration of a Beta-Gamma Detector

    SciTech Connect

    Cooper, Matthew W.; Ely, James H.; Haas, Derek A.; Hayes, James C.; McIntyre, Justin I.; Lidey, Lance S.; Schrom, Brian T.

    2013-04-10

    Abstract- Identification and quantification of nuclear events such as the Fukushima reactor failure and nuclear explosions rely heavily on the accurate measurement of radioxenon releases. One radioxenon detection method depends on detecting beta-gamma coincident events paired with a stable xenon measurement to determine the concentration of a plume. Like all measurements, the beta-gamma method relies on knowing the detection efficiency for each isotope measured. Several methods are commonly used to characterize the detection efficiency for a beta-gamma detector. The most common method is using a NIST certified sealed source to determine the efficiency. A second method determines the detection efficiencies relative to an already characterized detector. Finally, a potentially more accurate method is to use the expected sample to perform an absolute efficiency calibration; in the case of a beta-gamma detector, this relies on radioxenon gas samples. The complication of the first method is it focuses only on the gamma detectors and does not offer a solution for determining the beta efficiency. The second method listed is not similarly constrained, however it relies on another detector to have a well-known efficiency calibration. The final method using actual radioxenon samples to make an absolute efficiency determination is the most desirable, but until recently it was not possible to produce all four isotopically pure radioxenon. The production, by University of Texas (UT), of isotopically pure radioxenon has allowed the beta-gamma detectors to be calibrated using the absolute efficiency method. The first four radioxenon isotope calibration will be discussed is this paper.

  14. Predictive value of determinations of zinc protoporphyrin for increased blood lead concentrations.

    PubMed

    Froom, P; Kristal-Boneh, E; Benbassat, J; Ashkanazi, R; Ribak, J

    1998-06-01

    Blood lead (PbB) and red cell zinc protoporphyrin (ZPP) concentrations are widely used biomarkers for lead toxicity. It is uncertain, however, whether either or both are needed for monitoring lead exposure and how discordant PbB and ZPP values should be interpreted. We reviewed the results of PbB and ZPP determinations in 94 workers in a lead-battery plant over a 13-year period and retrieved all 807 sets of tests in which both PbB and ZPP were available, with a follow-up PbB value 6 months later. PbB exceeded 1.93 micromol/L (40 microg/dL) in 414 (51%), and 2.90 micromol/L (60 microg/dL) in 105 (14%) of the blood samples. We derived the test properties of various ZPP concentrations for concurrent "toxic" PbB concentrations, defined as > or = 1.93 and 2.90 micromol/L (40 and 60 microg/dL). The results indicated that, given a population of lead-exposed workers with a 10% prevalence of PbB of > or = 2.90 micromol/L (60 microg/dL), a policy of testing PbB only in those with ZPP > 0.71 micromol/L (40 microg/dL) would obviate 42% of the PbB tests, but would miss about three cases with toxic PbB concentrations in every 200 workers at risk. A finding of increased ZPP concentrations with a concurrent "nontoxic" PbB was associated with an increased risk of a toxic PbB concentration 6 months later. We conclude that (a) screening by testing only ZPP does not safeguard exposed persons against lead toxicity, and (b) the frequency of PbB monitoring should be guided by estimates of the risk of future lead toxicity in individual workers. PMID:9625054

  15. Impact of dietary manganese concentration on status criteria to determine manganese requirement in piglets.

    PubMed

    Pallauf, J; Kauer, C; Most, E; Habicht, S D; Moch, J

    2012-12-01

    The Mn requirement for pigs is not well established. This study aimed to find criteria for assessing growing piglet supply status for Mn and to determine whether the current Mn recommendations meet the requirements for piglets. Thirty-six weaned male castrated 27-day-old piglets (7.24 ± 0.69 kg) were randomized into six groups of six piglets each and housed individually in stainless steel metabolic cages for 42 days. The piglets were fed a diet based on skimmed milk powder and corn starch with increasing Mn concentrations (0.24; 2; 4; 8; 16; or 32 mg Mn/kg diet as-fed). In week 6, Mn0.24 led to reduced feed intake (p < 0.05). Manganese concentrations in blood, liver, kidney, lung, heart, phalanx proximalis, pancreas and skeletal muscle were influenced by the dietary Mn supply (p < 0.05). The activity of the Mn-containing superoxide dismutase in the heart as well as relative arginase activity in the liver were lower in groups Mn0.24, Mn2 and Mn4 compared with the higher supplemented groups (p < 0.05). The relative arginase activity increased clearly with enhanced dietary Mn up to 16 mg/kg and correlated with Mn concentration in the liver. Manganese concentrations in the liver, kidney and phalanx proximalis seem to be suitable biomarkers for Mn status. A 4 mg/kg dietary Mn concentration recommended by NRC (1998, Nutrient Requirements of Swine. National Academy Press, Washington DC.) did not fulfil piglet requirements. Under the conditions investigated, 16 mg Mn/kg diet were necessary to reach a plateau in specific enzyme activity and Mn concentration in organs. PMID:21883497

  16. Bias in determining aluminum concentrations: Comparison of digestion methods and implications on Al management.

    PubMed

    He, Y Thomas; Ziemkiewicz, Paul F

    2016-09-01

    Aluminum is an important aquatic contaminant due to its ubiquity, toxicity and low regulatory discharge limits. Aluminum is mobilized in mining related, acidic drainage and is commonly a regulated pollutant. However, while aquatic toxicity studies and toxicity criteria are based on dissolved aluminum(Ald), discharge levels are, for statutory reasons, based on total recoverable aluminum (Alt). The rationale for using total recoverable aluminum recognizes the potential for the release of exchangeable, toxic cations or dissolution of metastable metal flocs in the event the discharge enters an acidic receiving stream. The digestion methods used in determining total recoverable metals are not meant to dissolve aluminosilicate clay particles but we found that they do, resulting in positively biased total recoverable aluminum values. This study explored the interaction between total suspended solids (TSS) and total recoverable aluminum using three digestion methods to evaluate which method introduced the least bias. Using field collected water and sediment samples from two coal mine drainage sites in Central West Virginia, three total recoverable digestion methods (USEPA Method 200.7, M1; USGS In-Bottle method, M2; and a Modified In-Bottle method, M3) were used to determine total recoverable aluminum across a range of total suspended solids concentrations. Baseline simulation experiments were conducted at pH 2.5, 3.5, 4.5 and 5.5 at different total suspended solids concentrations. Results indicated that dissolved aluminum did not respond to increasing total suspended solids concentrations while determined total recoverable aluminum increased with total suspended solids, indicating varying degrees of clay dissolution and, thus bias in the total recoverable aluminum concentration. While all three digestion methods overestimated total recoverable aluminum, at the same total suspended solids concentration, total recoverable aluminum extracted by USEPA Method 200.7 (M1) was

  17. Determination of first flush criteria using dynamic EMCs (event mean concentrations) on highway stormwater runoff.

    PubMed

    Kim, L H; Jeong, S M; Ko, S O

    2007-01-01

    Recently the Ministry of Environment in Korea has developed the total maximum daily load program in accordance with the target pollutant and its concentration goal on four major large rivers. Since the program is largely related to regional development, nonpoint source control is both important and topical. Of the various nonpoint sources, highways are stormwater intensive land uses since they are impervious and have high pollutant mass emissions from vehicular activity. The event mean concentration (EMC) is useful in estimating the loadings to receiving water bodies. However, the EMC does not provide information on the time varying changes in pollutant concentration or mass emissions, which are often important for best management practice development, or understanding shock loads. Therefore, in this study a new concept, the dynamic EMC determination method, will be introduced to clearly verify the relationship between EMC and the first flush effect. Three monitoring sites in Daejeon metropolitan city areas were equipped with an automatic rainfall gauge and a flow meter for accumulating the data such as rainfall and runoff flow. The dynamic EMC method was applied to more than 17 events, and the improved first flush criteria were determined on the ranges of storm duration and accumulated rainfall. PMID:17410842

  18. Method and apparatus for determining clay counter-ion concentration in shaly sands

    SciTech Connect

    Scala, C.

    1987-10-06

    This patent describes a method for determining, in situ, clay counter-ion concentrations in a fluid bearing shaly sand earth formation penetrated by a well borehole, comprising the steps of: (a) detecting in a well borehole at a particular depth level natural gamma radiation emanating from the earth formations penetrated by the borehole as count rate signals. Then separating the detected gamma radiation signals into an energy spectrum of naturally occurring gamma radiation count rate signals as a function of energy and generating signals representative of the energy spectrum of the count rates of naturally occurring gamma radiation at the particular depth level; (b) comparing the representative count rate signals with standard gamma ray energy spectra representative of natural radioactive elements found in the earth formations penetrated by a well borehole. Thereby separating out gamma ray count rates attributable to at least uranium U, thorium Th, and potassium K occurring in the earth formations; (c) measuring the porosity phi of the earth formation at the particular depth level and normalizing the count rates attributable to uranium U and thorium Th at the particular depth level; (d) determining the clay counter ion concentration Q/sub v/ of the earth formations at the particular depth level by using a predetermined functional relationship and obtaining a signal representative of Q/sub v/ at the particular depth level; and, (e) recording the representative clay counter-ion concentration Q/sub v/ signal as a function of borehole depth.

  19. Determining concentrations of 2-bromoallyl alcohol and dibromopropene in ground water using quantitative methods

    USGS Publications Warehouse

    Panshin, Sandra Y.

    1997-01-01

    A method for determining levels of 2-bromoallyl alcohol and 2,3-dibromopropene from ground-water samples using liquid/liquid extraction followed by gas chromatography/mass spectrometry is described. Analytes were extracted from the water using three aliquots of dichloromethane. The aliquots were combined and reduced in volume by rotary evaporation followed by evaporation using a nitrogen stream. The extracts were analyzed by capillary-column gas chromatography/mass spectrometry in the full-scan mode. Estimated method detection limits were 30 nanograms per liter for 2-bromoallyl alcohol and 10 nanograms per liter for 2,3-dibromopropene. Recoveries were determined by spiking three matrices at two concentration levels (0.540 and 5.40 micrograms per liter for 2-bromoallyl alcohol; and 0.534 and 5.34micro-grams per liter for dibromopropene). For seven replicates of each matrix at the high concentration level, the mean percent recoveries ranged from 43.9 to 64.9 percent for 2-bromoallyl alcohol, and from 87.5 to 99.3 percent for dibromopropene. At the low concentration level, the mean percent recoveries ranged from 43.8 to 95.2 percent for 2-bromoallyl alcohol, and from 71.3 to 84.9 percent for dibromopropene.

  20. The determination of water quality and metal concentrations of Ampang Hilir Lake, Selangor, Peninsular Malaysia.

    PubMed

    Said, Khaled S A; Shuhaimi-Othman, M; Ahmad, A K

    2012-05-01

    A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Ampang Hilir Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using Hydrolab Data Sonde 4 and Surveyor 4 a water quality multi probe (USA). Six metals which were cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Perkin Elmer Elan, model 9000.The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur. PMID:24163953

  1. Using Photon Activation Analysis To Determine Concentrations Of Unknown Components In Reference Materials

    SciTech Connect

    Green, Jaromy; Sun, Zaijing; Wells, Doug; Maschner, Herb

    2011-06-01

    Using certified multi-element reference materials for instrumental analyses one frequently is confronted with the embarrassing fact that the concentration of some desired elements are not given in the respective certificate, nonetheless are detectable, e.g. by photon activation analysis (PAA). However, these elements might be determinable with sufficient quality of the results using scaling parameters and the well-known quantities of a reference element within the reference material itself. Scaling parameters include: activation threshold energy, Giant Dipole Resonance (GDR) peak and endpoint energy of the bremsstrahlung continuum; integrated photo-nuclear cross sections for the isotopes of the reference element; bremsstrahlung continuum integral; target thickness; photon flux density. Photo-nuclear cross sections from the unreferenced elements must be known, too. With these quantities, the integral was obtained for both the known and unknown elements resulting in an inference of the concentration of the unreported element based upon the reported value, thus also the concentration of the unreferenced element in the reference material. A similar method to determine elements using the basic nuclear and experimental data has been developed for thermal neutron activation analysis some time ago (k{sub 0} Method).

  2. Use of SPMDs to determine average water concentration of polycyclic aromatic hydrocarbons in urban stormwater runoff

    SciTech Connect

    DeVita, W.; Crunkilton, R.

    1995-12-31

    Semipermeable polymeric membrane devices (SPMDS) were deployed for 30 day periods to monitor polycyclic aromatic hydrocarbons (PAHs) in an urban stream which receives much of its flow from urban runoff. SPMDs are capable of effectively sampling several liters of water per day for some PAHs. Unlike conventional methods, SPMDs sample only those non-polar organic contaminants which are truly dissolved and available for bioconcentration. Also, SPMDs may concentrate contaminants from episodic events such as stormwater discharge. The State of Wisconsin has established surface water quality criteria based upon human lifetime cancer risk of 23 ppt for benzo(a)pyrene and 23 ppt as the sum of nine other potentially carcinogenic PAHs. Bulk water samples analyzed by conventional methodology were routinely well above this criteria, but contained particulate bound PAHs as well as PAHs bound by dissolved organic carbon (DOC) which are not available for bioconcentration. Average water concentrations of dissolved PAHs determined using SPMDs were also above this criteria. Variables used for determining water concentration included sampling rate at the exposure temperature, length of exposure and estimation of biofouling of SPMD surface.

  3. Concentration Sensing by the Moving Nucleus in Cell Fate Determination: A Computational Analysis.

    PubMed

    Aggarwal, Varun; Dickinson, Richard B; Lele, Tanmay P

    2016-01-01

    During development of the vertebrate neuroepithelium, the nucleus in neural progenitor cells (NPCs) moves from the apex toward the base and returns to the apex (called interkinetic nuclear migration) at which point the cell divides. The fate of the resulting daughter cells is thought to depend on the sampling by the moving nucleus of a spatial concentration profile of the cytoplasmic Notch intracellular domain (NICD). However, the nucleus executes complex stochastic motions including random waiting and back and forth motions, which can expose the nucleus to randomly varying levels of cytoplasmic NICD. How nuclear position can determine daughter cell fate despite the stochastic nature of nuclear migration is not clear. Here we derived a mathematical model for reaction, diffusion, and nuclear accumulation of NICD in NPCs during interkinetic nuclear migration (INM). Using experimentally measured trajectory-dependent probabilities of nuclear turning, nuclear waiting times and average nuclear speeds in NPCs in the developing zebrafish retina, we performed stochastic simulations to compute the nuclear trajectory-dependent probabilities of NPC differentiation. Comparison with experimentally measured nuclear NICD concentrations and trajectory-dependent probabilities of differentiation allowed estimation of the NICD cytoplasmic gradient. Spatially polarized production of NICD, rapid NICD cytoplasmic consumption and the time-averaging effect of nuclear import/export kinetics are sufficient to explain the experimentally observed differentiation probabilities. Our computational studies lend quantitative support to the feasibility of the nuclear concentration-sensing mechanism for NPC fate determination in zebrafish retina. PMID:26872214

  4. An acetylcholinesterase biosensor for determination of low concentrations of Paraoxon and Dichlorvos.

    PubMed

    Di Tuoro, D; Portaccio, M; Lepore, M; Arduini, F; Moscone, D; Bencivenga, U; Mita, D G

    2011-12-15

    The characterization of an economic and ease-to-use carbon paste acetylcholinesterase (AChE) based biosensor to determine the concentration of pesticides Paraoxon and Dichlorvos is discussed. AChE hydrolyses acetylthiocholine (ATCh) in thiocoline (TC) and acetic acid (AA). When AChE is immobilized into a paste carbon working electrode kept at +410 mV vs. Ag/AgCl electrode, the enzyme reaction rate using acetylthiocholine chloride (ATCl) as substrate is monitored as a current intensity. Because Paraoxon and Dichlorvos inhibit the AChE reaction, the decrease of the current intensity, at fixed ATCl concentration, is a measure of their concentration. Linear calibration curves for Paraoxon and Dichlorvos determination have been obtained. The detection limits resulted to be 0.86 ppb and 4.2 ppb for Paraoxon and Dichlorvos, respectively, while the extension of the linear range was up 23 ppb for the former pesticide and up to 33 ppb for the latter. Because the inhibited enzyme can be reactivated when immediately treated with an oxime, the biosensor reactivation has been studied when 1,1'-trimethylene bis 4-formylpyridinium bromide dioxime (TMB-4) and pyridine 2-aldoxime methiodide (2-PAM) were used. TMB-4 resulted more effective. The comparison with the behavior of similar AChE based biosensors is also presented. PMID:21600321

  5. Quantitative Determination of Fusarium proliferatum Concentration in Intact Garlic Cloves Using Near-Infrared Spectroscopy

    PubMed Central

    Tamburini, Elena; Mamolini, Elisabetta; De Bastiani, Morena; Marchetti, Maria Gabriella

    2016-01-01

    Fusarium proliferatum is considered to be a pathogen of many economically important plants, including garlic. The objective of this research was to apply near-infrared spectroscopy (NIRS) to rapidly determine fungal concentration in intact garlic cloves, avoiding the laborious and time-consuming procedures of traditional assays. Preventive detection of infection before seeding is of great interest for farmers, because it could avoid serious losses of yield during harvesting and storage. Spectra were collected on 95 garlic cloves, divided in five classes of infection (from 1-healthy to 5-very highly infected) in the range of fungal concentration 0.34–7231.15 ppb. Calibration and cross validation models were developed with partial least squares regression (PLSR) on pretreated spectra (standard normal variate, SNV, and derivatives), providing good accuracy in prediction, with a coefficient of determination (R2) of 0.829 and 0.774, respectively, a standard error of calibration (SEC) of 615.17 ppb, and a standard error of cross validation (SECV) of 717.41 ppb. The calibration model was then used to predict fungal concentration in unknown samples, peeled and unpeeled. The results showed that NIRS could be used as a reliable tool to directly detect and quantify F. proliferatum infection in peeled intact garlic cloves, but the presence of the external peel strongly affected the prediction reliability. PMID:27428978

  6. Concentration Sensing by the Moving Nucleus in Cell Fate Determination: A Computational Analysis

    PubMed Central

    Aggarwal, Varun; Dickinson, Richard B.; Lele, Tanmay P.

    2016-01-01

    During development of the vertebrate neuroepithelium, the nucleus in neural progenitor cells (NPCs) moves from the apex toward the base and returns to the apex (called interkinetic nuclear migration) at which point the cell divides. The fate of the resulting daughter cells is thought to depend on the sampling by the moving nucleus of a spatial concentration profile of the cytoplasmic Notch intracellular domain (NICD). However, the nucleus executes complex stochastic motions including random waiting and back and forth motions, which can expose the nucleus to randomly varying levels of cytoplasmic NICD. How nuclear position can determine daughter cell fate despite the stochastic nature of nuclear migration is not clear. Here we derived a mathematical model for reaction, diffusion, and nuclear accumulation of NICD in NPCs during interkinetic nuclear migration (INM). Using experimentally measured trajectory-dependent probabilities of nuclear turning, nuclear waiting times and average nuclear speeds in NPCs in the developing zebrafish retina, we performed stochastic simulations to compute the nuclear trajectory-dependent probabilities of NPC differentiation. Comparison with experimentally measured nuclear NICD concentrations and trajectory-dependent probabilities of differentiation allowed estimation of the NICD cytoplasmic gradient. Spatially polarized production of NICD, rapid NICD cytoplasmic consumption and the time-averaging effect of nuclear import/export kinetics are sufficient to explain the experimentally observed differentiation probabilities. Our computational studies lend quantitative support to the feasibility of the nuclear concentration-sensing mechanism for NPC fate determination in zebrafish retina. PMID:26872214

  7. Quantitative Determination of Fusarium proliferatum Concentration in Intact Garlic Cloves Using Near-Infrared Spectroscopy.

    PubMed

    Tamburini, Elena; Mamolini, Elisabetta; De Bastiani, Morena; Marchetti, Maria Gabriella

    2016-01-01

    Fusarium proliferatum is considered to be a pathogen of many economically important plants, including garlic. The objective of this research was to apply near-infrared spectroscopy (NIRS) to rapidly determine fungal concentration in intact garlic cloves, avoiding the laborious and time-consuming procedures of traditional assays. Preventive detection of infection before seeding is of great interest for farmers, because it could avoid serious losses of yield during harvesting and storage. Spectra were collected on 95 garlic cloves, divided in five classes of infection (from 1-healthy to 5-very highly infected) in the range of fungal concentration 0.34-7231.15 ppb. Calibration and cross validation models were developed with partial least squares regression (PLSR) on pretreated spectra (standard normal variate, SNV, and derivatives), providing good accuracy in prediction, with a coefficient of determination (R²) of 0.829 and 0.774, respectively, a standard error of calibration (SEC) of 615.17 ppb, and a standard error of cross validation (SECV) of 717.41 ppb. The calibration model was then used to predict fungal concentration in unknown samples, peeled and unpeeled. The results showed that NIRS could be used as a reliable tool to directly detect and quantify F. proliferatum infection in peeled intact garlic cloves, but the presence of the external peel strongly affected the prediction reliability. PMID:27428978

  8. A new method for rapid determination of carbohydrate and total carbon concentrations using UV spectrophotometry.

    PubMed

    Albalasmeh, Ammar A; Berhe, Asmeret Asefaw; Ghezzehei, Teamrat A

    2013-09-12

    A new UV spectrophotometry based method for determining the concentration and carbon content of carbohydrate solution was developed. This method depends on the inherent UV absorption potential of hydrolysis byproducts of carbohydrates formed by reaction with concentrated sulfuric acid (furfural derivatives). The proposed method is a major improvement over the widely used Phenol-Sulfuric Acid method developed by DuBois, Gilles, Hamilton, Rebers, and Smith (1956). In the old method, furfural is allowed to develop color by reaction with phenol and its concentration is detected by visible light absorption. Here we present a method that eliminates the coloration step and avoids the health and environmental hazards associated with phenol use. In addition, avoidance of this step was shown to improve measurement accuracy while significantly reducing waiting time prior to light absorption reading. The carbohydrates for which concentrations and carbon content can be reliably estimated with this new rapid Sulfuric Acid-UV technique include: monosaccharides, disaccharides and polysaccharides with very high molecular weight. PMID:23911443

  9. Lethal body concentrations and accumulation patterns determine time-dependent toxicity of cadmium in soil arthropods

    SciTech Connect

    Crommentuijn, T.; Doodeman, C.J.A.M.; Doornekamp, A.; Pol, J.J.C. van der; Bedaux, J.J.M.; Gestel, C.A.M. van )

    1994-11-01

    Time-dependent toxicity in bioassays is usually explained in terms of uptake and elimination kinetics of the toxicant. By comparing different species with essentially different accumulation kinetics, a firm test of this concept may be made. This article compares the sensitivity of six soil arthropods, the collembolans Orchesella cincta and Tomocerus minor, the oribatid mite Platynothrus peltifer, the isopods Porcellio scaber and Oniscus asellus, and the diplopod Cylindroiulus britannicus, when exposed to cadmium in the food. Survival was determined at various time intervals; accumulation of cadmium in the animals was measured at one time interval. Kinetic-based toxicity models were fitted to the data, and estimates were obtained for lethal body concentration, uptake rate constant, elimination rate constant, and ultimate LC50. Two different accumulation patterns could be discerned; these were correlated with time-survival relationships. One, species that have the possibility to eliminate cadmium will reach an equilibrium for the internal concentration and also an ultimate LC50. Two, species that are unable to eliminate cadmium but store it in the body will have an ultimate LC50 equal to zero. For these species the time in which the lethal body concentration is reached is more important. Taxonomically related species appeared to have comparable accumulation patterns, but lethal body concentrations differed. It is concluded that knowledge of the accumulation pattern is indispensable for the evaluation of species' sensitivities to toxicants.

  10. Method for the determination of concentration and stable carbon isotope ratios of atmospheric phenols

    NASA Astrophysics Data System (ADS)

    Saccon, M.; Busca, R.; Facca, C.; Huang, L.; Irei, S.; Kornilova, A.; Lane, D.; Rudolph, J.

    2013-05-01

    A method for the determination of the stable carbon isotopic composition of atmospheric nitrophenols in the gas and particulate phases is presented. It has been proposed to use the combination of concentration and isotope ratio measurements of precursor and product to test the applicability of results of laboratory studies to the atmosphere. Nitrophenols are suspected to be secondary products formed specifically from the photooxidation of volatile organic compounds. XAD-4™ resin was used as an adsorbent on quartz filters to sample ambient phenols using conventional high-volume air samplers at York University in Toronto, Canada. Filters were extracted in acetonitrile, with a HPLC clean-up step and a solid phase extraction step prior to derivatization with BSTFA. Concentration measurements were done with gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry was used for isotope ratio analysis. The technique presented allows for atmospheric compound-specific isotopic composition measurements for five semi-volatile phenols with an estimated accuracy of 0.3‰ to 0.5‰ at atmospheric concentrations exceeding 0.1 ng m-3 while the detection limits for concentration measurements are in the pg m-3 range. Isotopic fractionation throughout the entire extraction procedure and analysis was proven to be below the precision of the isotope ratio measurements. The method was tested by conducting ambient measurements from September to December 2011.

  11. Method for the determination of concentration and stable carbon isotope ratios of atmospheric phenols

    NASA Astrophysics Data System (ADS)

    Saccon, M.; Busca, R.; Facca, C.; Huang, L.; Irei, S.; Kornilova, A.; Lane, D.; Rudolph, J.

    2013-11-01

    A method for the determination of the stable carbon isotopic composition of atmospheric nitrophenols in the gas and particulate phases is presented. It has been proposed to use the combination of concentration and isotope ratio measurements of precursor and product to test the applicability of results of laboratory studies to the atmosphere. Nitrophenols are suspected to be secondary products formed specifically from the photooxidation of volatile organic compounds. XAD-4TM resin was used as an adsorbent on quartz filters to sample ambient phenols using conventional high volume air samplers at York University in Toronto, Canada. Filters were extracted in acetonitrile, with a HPLC (high-performance liquid chromatography) clean-up step and a solid phase extraction step prior to derivatization with BSTFA (bis(trimethylsilyl) trifluoroacetamide). Concentration measurements were done with gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry was used for isotope ratio analysis. The technique presented allows for atmospheric compound-specific isotopic composition measurements for five semi-volatile phenols with an estimated accuracy of 0.3-0.5‰ at atmospheric concentrations exceeding 0.1 ng m-3 while the detection limits for concentration measurements are in the pg m-3 range. Isotopic fractionation throughout the entire extraction procedure and analysis was proven to be below the precision of the isotope ratio measurements. The method was tested by conducting ambient measurements from September to December 2011.

  12. Determination of nitrogen spin concentration in diamond using double electron-electron resonance

    NASA Astrophysics Data System (ADS)

    Stepanov, Viktor; Takahashi, Susumu

    2016-07-01

    Diamond has been extensively investigated recently due to a wide range of potential applications of nitrogen-vacancy (NV) defect centers existing in a diamond lattice. The applications include magnetometry and quantum information technologies, and long decoherence time (T2) of NV centers is critical for those applications. Although it has been known that T2 highly depends on the concentration of paramagnetic impurities in diamond, precise measurement of the impurity concentration remains challenging. In the present work we show a method to determine a wide range of the nitrogen concentration (n ) in diamond using a wide-band high-frequency electron spin resonance and double electron-electron resonance spectrometer. Moreover, we investigate T2 of the nitrogen impurities and show the relationship between T2 and n . The method developed here is applicable for various spin systems in solid and implementable in nanoscale magnetic resonance spectroscopy with NV centers to characterize the concentration of the paramagnetic spins within a microscopic volume.

  13. Determination of elemental concentrations of iron gall ink components by PIXE

    NASA Astrophysics Data System (ADS)

    Budnar, Miloš; Simčič, Jure; Uršič, Mitja; Rupnik, Zdravko; Kolar, Jana; Strlič, Matija

    2003-08-01

    The harmful effects of the iron gall ink on the supporting media (i.e. paper, parchment) are known for a long time. High contents of the catalytic ions and acids present in the ink can cause corrosion of the support and even its irreversible damage. Several historical documents from National and University Library (NUL) are being studied. The samples were measured nondestructively by the in-air PIXE for determination of the iron gall elemental composition. The measured concentrations prove that the analyzed inks contain a variety of different transition metals, which may influence the ink's corrosive character. For already measured documents dating from 14th to 19th century the ink and paper elemental concentrations and their ratios to iron were studied by the statistical methods.

  14. Laboratory application of laser grain-size analyzer in determining suspended sediment concentration

    NASA Astrophysics Data System (ADS)

    Liu, Xiao; Feng, Xiuli; Liu, Jie; Lin, Lin

    2014-06-01

    Suspended sediment concentration (SSC) is an important parameter in marine sedimentology. With the development of technology, many acoustic and optical devices, such as the Laser In-Situ Scattering and Transmissometry, have been designed to measure in situ SSC and grain size distribution. But due to fund or other restrictions, many experiments were only conducted in laboratory, using an indoor laser grain-size analyzer and gravimetric method to measure grain size distribution and concentration, respectively. In this study the laboratory experiment is simplified by omitting the tiring step of gravimetric method. The connections between SSC and other parameters (obscuration, D50 and sorting index) were investigated based on 124 surface sediment samples collected from different offshore areas. A new method is developed for determining SSC in laboratory using a laser grain-size analyzer.

  15. Determination of Concentrations of Radioactive Nuclides in Soil Samples using Gamma Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Adil, Arsalan; Weaver, Joshua

    2015-10-01

    A hyper-pure Germanium detector system was used to determine the contents and concentrations of various nuclides in soil samples collected from different parts of the United States. These include areas in close proximity to nuclear power plants, areas susceptible to nuclear fallout from weapons testing from the pre Comprehensive Nuclear Test Ban Treaty (CTBT) period, and areas vulnerable to fallout from Fukushima from the west coast. The concentrations of naturally occurring nuclides in the 238U, 232Th, and 40K decay chains as well as that of synthetic isotopes of 137Cs and 60Co were measured with the aid of Genie-2000 and Radware (gf3m). An efficiency curve was obtained by designing a simulation and compared with standard sources. The research, now in its next stage, aims to do the same in samples from Karachi (Pakistan) which is home to three nuclear power plant projects but has no available baseline radioactivity measurements. University of Richmond.

  16. Dosimetry determines the initial OH radical concentration in fast photochemical oxidation of proteins (FPOP).

    PubMed

    Niu, Ben; Zhang, Hao; Giblin, Daryl; Rempel, Don L; Gross, Michael L

    2015-05-01

    Fast photochemical oxidation of proteins (FPOP) employs laser photolysis of hydrogen peroxide to give OH radicals that label amino acid side-chains of proteins on the microsecond time scale. A method for quantitation of hydroxyl radicals after laser photolysis is of importance to FPOP because it establishes a means to adjust the yield of •OH, offers the opportunity of tunable modifications, and provides a basis for kinetic measurements. The initial concentration of OH radicals has yet to be measured experimentally. We report here an approach using isotope dilution gas chromatography/mass spectrometry (GC/MS) to determine quantitatively the initial •OH concentration (we found ~0.95 mM from 15 mM H2O2) from laser photolysis and to investigate the quenching efficiencies for various •OH scavengers. PMID:25712620

  17. Determination of spore concentration in Bacillus thuringiensis through the analysis of dipicolinate by capillary zone electrophoresis.

    PubMed

    He, Jin; Luo, Xiaofeng; Chen, Shouwen; Cao, Lili; Sun, Ming; Yu, Ziniu

    2003-04-25

    A new capillary zone electrophoresis (CZE) method for the analysis of dipicolinic acid, a specific component found in spores but not in vegetative cells, was used to determine spore concentration in Bacillus thuringiensis according to the relationship between the spore concentration and the content of dipicolinate. The quantitative relationship was established by using purified spores. Electrolyte conditions that affected the separation efficiency of dipicolinate and the reproducibility were investigated. With 10 mM phosphate, 10 mM ethylenediaminetetraacetic acid and 0.25 mM tetradecyltrimethylammonium bromide at pH 6.2 as the carrier electrolyte, dipicolinate can be determined within 8 min at an applied voltage of -25 kV (anode at detector) and a capillary temperature of 25 degrees C. The method has a high separation efficiency with which the number of theoretical plates is above 300,000 plates m(-1). The relative standard deviations for migration time and peak area are less than 0.5% and 2.0%, respectively. The detection limit for dipicolinate was 10 ng ml(-1), which corresponds to 7.2 x 10(5) spores ml(-1). The method was used to determine spores in fermentation broths, and the results obtained agreed well with the values obtained by plate counting. PMID:12779231

  18. Flow injection method for the determination of silver concentration in drinking water for spacecrafts.

    PubMed

    Bruzzoniti, Maria Concetta; Kobylinska, Dorota Korte; Franko, Mladen; Sarzanini, Corrado

    2010-04-14

    A flow injection method has been developed for determination of silver. The method is based on a reduction reaction with sodium borohydride which leads to the formation of a colloidal species which is monitored at a wavelength of 390 nm. The reaction variables flow rate, sodium borohydride concentration and pH, which affect sensitivity, were investigated and their effects were established using a two-levels, three-factor experimental design. Further optimization of manifold variables (reaction coil and injection volume) allowed us to determine silver in the range 0.050-5.0 mg L(-1) with a minimum detectable concentration of 0.050 mg L(-1). Silver is added, as biocide, to drinking water for spacecrafts. The chemical species of silver, present in this kind of sample, were characterized by a procedure based on the selective retention of Ag(+) onto a 2.2.2. cryptand based substrate followed by determination of the non-bound and bound (after elution) Ag(+) by the FIA method. The method optimized was applied to a drinking water sample provided for the launch with the Automated Transfer Vehicle (ATV) module Jule Verne to the International Space Station (March 9, 2008). PMID:20381692

  19. Determining Airborne Concentrations of Spatial Repellent Chemicals in Mosquito Behavior Assay Systems

    PubMed Central

    Martin, Nicholas J.; Smith, Philip A.; Achee, Nicole L.; DeLong, Gerald T.

    2013-01-01

    Background Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR). Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI) in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions. Methodology/Principal Findings A thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT) in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m3 (n = 17; SD = 0.45) and 1.42 µg/m3 (n = 30; SD = 0.96). Conclusions/Significance The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h) SR concentrations in small volume (<100 L) samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds. PMID:24015195

  20. New method for the direct determination of dissolved Fe(III) concentration in acid mine waters

    USGS Publications Warehouse

    To, T.B.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.; McCleskey, R.B.

    1999-01-01

    A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II) >> Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes in Fe reduction-oxidation distribution. Complexed Fe(II) is cleanly removed using a silica-based, reversed-phase adsorbent, yielding excellent isolation of the Fe(III) complex. Iron(III) concentration is measured colorimetrically or by graphite furnace atomic absorption spectrometry (GFAAS). The method requires inexpensive commercial reagents and simple procedures that can be used in the field. Calcium(II), Ni(II), Pb(II), AI(III), Zn(II), and Cd(II) cause insignificant colorimetric interferences for most acid mine waters. Waters containing >20 mg of Cu/L could cause a colorimetric interference and should be measured by GFAAS. Cobalt(II) and Cr(III) interfere if their molar ratios to Fe(III) exceed 24 and 5, respectively. Iron(II) interferes when its concentration exceeds the capacity of the complexing ligand (14 mg/L). Because of the GFAAS elemental specificity, only Fe(II) is a potential interferent in the GFAAS technique. The method detection limit is 2 ??g/L (40 nM) using GFAAS and 20 ??g/L (0.4 ??M) by colorimetry.A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II)???Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes

  1. Practical Considerations for Determination of Glass Transition Temperature of a Maximally Freeze Concentrated Solution.

    PubMed

    Pansare, Swapnil K; Patel, Sajal Manubhai

    2016-08-01

    Glass transition temperature is a unique thermal characteristic of amorphous systems and is associated with changes in physical properties such as heat capacity, viscosity, electrical resistance, and molecular mobility. Glass transition temperature for amorphous solids is referred as (T g), whereas for maximally freeze concentrated solution, the notation is (T g'). This article is focused on the factors affecting determination of T g' for application to lyophilization process design and frozen storage stability. Also, this review provides a perspective on use of various types of solutes in protein formulation and their effect on T g'. Although various analytical techniques are used for determination of T g' based on the changes in physical properties associated with glass transition, the differential scanning calorimetry (DSC) is the most commonly used technique. In this article, an overview of DSC technique is provided along with brief discussion on the alternate analytical techniques for T g' determination. Additionally, challenges associated with T g' determination, using DSC for protein formulations, are discussed. The purpose of this review is to provide a practical industry perspective on determination of T g' for protein formulations as it relates to design and development of lyophilization process and/or for frozen storage; however, a comprehensive review of glass transition temperature (T g, T g'), in general, is outside the scope of this work. PMID:27193003

  2. Methods of determining electron concentrations in the magnetosphere from nose whistlers

    NASA Technical Reports Server (NTRS)

    Park, C. G.

    1972-01-01

    Whistler propagation in the magnetosphere was studied in detail to find accurate and economical means of determining the path latitude and the electron concentration along the path from whistler parameters of nose frequency and travel time at the nose. Longitudinal propagation in field aligned whistler ducts of cold plasma was assumed, and the earth's magnetic field was approximated by a centered dipole. The effects of whistler propagation in the earth-ionosphere waveguide and through the conjugate ionospheres were treated as small perturbations. Several alternative methods are described so that the most economical method may be chosen depending on the desired accuracy and the availability of a computer or a calculator.

  3. Determination of some radionucluides and heavy elements concentrations in concrete raw materials

    NASA Astrophysics Data System (ADS)

    ElFaham, Mohamed M.; Khalil, Osama M.; Elhassan, Asmaa; Salama, S.

    2015-08-01

    The presence of natural radionuclides in raw materials used in cement manufacturing was determined by using analytical methods. The used Raw materials are limestone, clay, slag, and gypsum, which be used with different concentrations in cement production. Different analytical techniques such as Laser Induced Breakdown Spectroscopy (LIBS) technique, Gamma spectroscopy, Inductively Coupled Plasma (ICP) spectroscopy, X-ray fluorescence spectroscopy (XRF), in addition to X-Ray Diffraction (XRD) for phase identification of a crystalline material. The obtained data show that there is no significant radiological hazards arising from using the present cement components in the different applications. XRD data shows that there is no crystalline structures in the raw materials.

  4. Non-invasive in vivo determination of the carotenoids beta-carotene and lycopene concentrations in the human skin using the Raman spectroscopic method

    NASA Astrophysics Data System (ADS)

    Darvin, M. E.; Gersonde, I.; Meinke, M.; Sterry, W.; Lademann, J.

    2005-08-01

    Resonance Raman spectroscopy was used as a fast and non-invasive optical method of measuring the absolute concentrations of beta-carotene and lycopene in living human skin. Beta-carotene and lycopene have different absorption values at 488 and 514.5 nm and, consequently, the Raman lines for beta-carotene and lycopene have different scattering efficiencies at 488 and 514.5 nm excitations. These differences were used for the determination of the concentrations of beta-carotene and lycopene. Using multiline Ar+ laser excitation, clearly distinguishable carotenoid Raman spectra can be obtained which are superimposed on a large fluorescence background. The Raman signals are characterized by two prominent Stokes lines at 1160 and 1525 cm-1, which have nearly identical relative intensities. Both substances were detected simultaneously. The Raman spectra are obtained rapidly, i.e. within about 10 s, and the required laser light exposure level is well within safety standards. The disturbance of the measurements by non-homogeneous skin pigmentation was avoided by using a relatively large measuring area of 35 mm2. It was shown that beta-carotene and lycopene distribution in human skin strongly depends upon the skin region studied and drastically changed inter-individually. Skin beta-carotene and lycopene concentrations are lower in smokers than in non-smokers and higher in the vegetarian group.

  5. Absolute cavity pyrgeometer

    DOEpatents

    Reda, Ibrahim

    2013-10-29

    Implementations of the present disclosure involve an apparatus and method to measure the long-wave irradiance of the atmosphere or long-wave source. The apparatus may involve a thermopile, a concentrator and temperature controller. The incoming long-wave irradiance may be reflected from the concentrator to a thermopile receiver located at the bottom of the concentrator to receive the reflected long-wave irradiance. In addition, the thermopile may be thermally connected to a temperature controller to control the device temperature. Through use of the apparatus, the long-wave irradiance of the atmosphere may be calculated from several measurements provided by the apparatus. In addition, the apparatus may provide an international standard of pyrgeometers' calibration that is traceable back to the International System of Units (SI) rather than to a blackbody atmospheric simulator.

  6. Spectrofluorimetric determination of second critical micellar concentration of SDS and SDS/Brij 30 systems.

    PubMed

    Romani, Ana Paula; Machado, Antonio Eduardo da Hora; Hioka, Noboru; Severino, Divinomar; Baptista, Mauricio S; Codognoto, Lúcia; Rodrigues, Maira R; de Oliveira, Hueder Paulo Moisés

    2009-03-01

    Potentially useful stead-state fluorimetric technique was used to determine the critical micellar concentrations (CMC(1) and CMC(2)) for two micellar media, one formed by SDS and the other by SDS/Brij 30. A comparative study based on conductimetric and surfacial tension measurements suggests that the CMC(1) estimated by the fluorimetric method is lower than the value estimated by these other techniques. Equivalent values were observed for SDS micelles without Brij 30 neutral co-surfactant. The use of acridine orange as fluorescent probe permitted to determine both CMC(1) and CMC(2). Based on it an explanation on aspects of micelle formation mechanism is presented, particularly based on a spherical and a rod like structures. PMID:18815872

  7. Determination of half-maximal inhibitory concentration using biosensor-based protein interaction analysis.

    PubMed

    Aykul, Senem; Martinez-Hackert, Erik

    2016-09-01

    Half-maximal inhibitory concentration (IC50) is the most widely used and informative measure of a drug's efficacy. It indicates how much drug is needed to inhibit a biological process by half, thus providing a measure of potency of an antagonist drug in pharmacological research. Most approaches to determine IC50 of a pharmacological compound are based on assays that utilize whole cell systems. While they generally provide outstanding potency information, results can depend on the experimental cell line used and may not differentiate a compound's ability to inhibit specific interactions. Here we show using the secreted Transforming Growth Factor-β (TGF-β) family ligand BMP-4 and its receptors as example that surface plasmon resonance can be used to accurately determine IC50 values of individual ligand-receptor pairings. The molecular resolution achievable wih this approach can help distinguish inhibitors that specifically target individual complexes, or that can inhibit multiple functional interactions at the same time. PMID:27365221

  8. Ion probe determinations of the rare earth concentrations of individual meteoritic phosphate grains

    NASA Technical Reports Server (NTRS)

    Crozaz, G.; Zinner, E.

    1985-01-01

    A new ion probe method for quantitative measurements of the concentrations of all the REE down to the ppm level in 5-20 micron spots is presented. The first application of the method is the determination of REE abundances in meteoritic phosphates. Results are shown to be in good agreement with previous INAA and ion probe determinations. The merrillites in the St. Severin amphoterite are richer in REE than the apatites (the enrichment factors, for various REE, range from 2.3 to 14.2) in contradiction with the results of Ebihara and Honda (1983). Provided good standards for other mineral phases are found or implanted marker ion techniques are used, the method should find a wide range of applications for the study of both terrestrial and extraterrestrial crystals at the microscopic level.

  9. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  10. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  11. Chemical Structure and Concentration of Intratumor Catabolites Determine Efficacy of Antibody Drug Conjugates

    PubMed Central

    Yu, Shang-Fan; Ma, Yong; Xu, Keyang; Dragovich, Peter S.; Pillow, Thomas H.; Liu, Luna; Del Rosario, Geoffrey; He, Jintang; Pei, Zhonghua; Sadowsky, Jack D.; Erickson, Hans K.; Hop, Cornelis E. C. A.; Khojasteh, S. Cyrus

    2016-01-01

    Despite recent technological advances in quantifying antibody drug conjugate (ADC) species, such as total antibody, conjugated antibody, conjugated drug, and payload drug in circulation, the correlation of their exposures with the efficacy of ADC outcomes in vivo remains challenging. Here, the chemical structures and concentrations of intratumor catabolites were investigated to better understand the drivers of ADC in vivo efficacy. Anti-CD22 disulfide-linked pyrrolobenzodiazepine (PBD-dimer) conjugates containing methyl- and cyclobutyl-substituted disulfide linkers exhibited strong efficacy in a WSU-DLCL2 xenograft mouse model, whereas an ADC derived from a cyclopropyl linker was inactive. Total ADC antibody concentrations and drug-to-antibody ratios (DAR) in circulation were similar between the cyclobutyl-containing ADC and the cyclopropyl-containing ADC; however, the former afforded the release of the PBD-dimer payload in the tumor, but the latter only generated a nonimmolating thiol-containing catabolite that did not bind to DNA. These results suggest that intratumor catabolite analysis rather than systemic pharmacokinetic analysis may be used to better explain and predict ADC in vivo efficacy. These are good examples to demonstrate that the chemical nature and concentration of intratumor catabolites depend on the linker type used for drug conjugation, and the potency of the released drug moiety ultimately determines the ADC in vivo efficacy. PMID:27417182

  12. Determination of Blood Glucose Concentration by Using Wavelet Transform and Neural Networks

    PubMed Central

    Ashok, Vajravelu; Kumar, Nirmal

    2013-01-01

    Background: Early and non-invasive determination of blood glucose level is of great importance. We aimed to present a new technique to accurately infer the blood glucose concentration in peripheral blood flow using non-invasive optical monitoring system. Methods: The data for the research were obtained from 900 individuals. Of them, 750 people had diabetes mellitus (DM). The system was designed using a helium neon laser source of 632.8 nm wavelength with 5mW power, photo detectors and digital storage oscilloscope. The laser beam was directed through a single optical fiber to the index finger and the scattered beams were collected by the photo detectors placed circumferentially to the transmitting fiber. The received signals were filtered using band pass filter and finally sent to a digital storage oscilloscope. These signals were then decomposed into approximation and detail coefficients using modified Haar Wavelet Transform. Back propagation neural and radial basis functions were employed for the prediction of blood glucose concentration. Results: The data of 450 patients were randomly used for training, 225 for testing and the rest for validation. The data showed that outputs from radial basis function were nearer to the clinical value. Significant variations could be seen from signals obtained from patients with DM and those without DM. Conclusion: The proposed non-invasive optical glucose monitoring system is able to predict the glucose concentration by proving that there is a definite variation in hematological distribution between patients with DM and those without DM. PMID:23645958

  13. An inversion algorithm for determining area-source emissions from downwind concentration measurements.

    PubMed

    Lehning, M; Shonnard, D R; Chang, D P; Bell, R L

    1994-10-01

    Measuring emissions from nonuniform area sources, such as waste repository sites, has been a difficult problem. A simple but reliable method is not available. An objective method of inverting downwind concentration measurements, utilizing an assumed form of atmospheric dispersion to reconstruct total emission rate and distribution, is described in this study. The Gaussian dispersion model is compared to a more realistic model based on K-theory and similarity expressions. A sensitivity analysis is presented indicating the atmospheric conditions under which a successful application of the method could be anticipated. Field releases of sulfur hexafluoride (SF6) from a simulated area source in flat terrain were conducted to check the method, ability to reconstruct source distribution, and total emission rate. The sensitivity analysis and the field study confirm that a few ground-level concentration measurements and a simple determination of the atmospheric dispersion characteristics are sufficient, under neutral to stable conditions, to obtain the total emission rate accurately. Reconstruction of the spatial pattern of the source is possible by utilizing concentration information from samplers located on two separate ground-level receptor lines, if a shift in the wind direction occurs and if it can be assumed that the total emission rate is time invariant. A method of cross-checking the accuracy of the reconstruction, using a simultaneous tracer release, is presented. PMID:7812684

  14. Determinants of Anemia and Hemoglobin Concentration in Haitian School-Aged Children.

    PubMed

    Iannotti, Lora L; Delnatus, Jacques R; Odom, Audrey R; Eaton, Jacob C; Griggs, Jennifer J; Brown, Sarah; Wolff, Patricia B

    2015-11-01

    Anemia diminishes oxygen transport in the body, resulting in potentially irreversible growth and developmental consequences for children. Limited evidence for determinants of anemia exists for school-aged children. We conducted a cluster randomized controlled trial in Haiti from 2012 to 2013 to test the efficacy of a fortified school snack. Children (N = 1,047) aged 3-13 years were followed longitudinally at three time points for hemoglobin (Hb) concentrations, anthropometry, and bioelectrical impedance measures. Dietary intakes, infectious disease morbidities, and socioeconomic and demographic factors were collected at baseline and endline. Longitudinal regression modeling with generalized least squares and logit models with random effects identified anemia risk factors beyond the intervention effect. At baseline, 70.6% of children were anemic and 2.6% were severely anemic. Stunting increased the odds of developing anemia (adjusted odds ratio [OR]: 1.48, 95% confidence interval [CI]: 1.05-2.08) and severe anemia (adjusted OR: 2.47, 95% CI: 1.30-4.71). Parent-reported vitamin A supplementation and deworming were positively associated with Hb concentrations, whereas fever and poultry ownership showed a negative relationship with Hb concentration and increased odds of severe anemia, respectively. Further research should explore the full spectrum of anemia etiologies in school children, including genetic causes. PMID:26350448

  15. Determining Absolute Zero Using a Tuning Fork

    ERIC Educational Resources Information Center

    Goldader, Jeffrey D.

    2008-01-01

    The Celsius and Kelvin temperature scales, we tell our students, are related. We explain that a change in temperature of 1 degree C corresponds to a change of 1 Kelvin and that atoms and molecules have zero kinetic energy at zero Kelvin, -273 degrees C. In this paper, we will show how students can derive the relationship between the Celsius and…

  16. Determining Absolute Zero in the Kitchen Sink.

    ERIC Educational Resources Information Center

    Otani, Robert; Siegel, Peter

    1991-01-01

    Presents an experiment to demonstrate Charles's Law of Ideal Gases by creating a constant-pressure thermometer from materials that can be found in the kitchen. Discusses the underlying mathematical relationships and a step-by-step description of the experiment. (MDH)

  17. Acute hypoproteinemic fluid overload: its determinants, distribution, and treatment with concentrated albumin and diuretics.

    PubMed

    Pappova, E; Bachmeier, W; Crevoisier, J L; Kollar, J; Kollar, M; Tobler, P; Zahler, H W; Zaugg, D; Lundsgaard-Hansen, P

    1977-01-01

    We simulated the use of massive volumes of crystalloid fluids as a treatment of acute plasma loss in a standardized experimental model and studied the factors determining the retention or excretion of the resulting acute hypoproteinemic fluid overload, its distribution within the body, and its treatment with concentrated albumin and diuretics. In accordance with the classic Starling concept, the serum protein level, i.e. the serum colloid osmotic pressure, determined the excretion/retention ratio of a given water and sodium load. Of the total fluid retention, fat and muscle each accommodated 25%, whereas the skin, which contributes only 7% to the total body weight, accounted for 37% and increased its volume by roughly one third. Concentrated albumin promoted fluid excretion in direct proportion to the achieved increment of the serum protein level and abolished the edema of fat, muscle and skin. Furosemide was virtually ineffective. The implications of these results for the 'adult respiratory distress syndrome' and disturbed wound healing are discussed and related to the concept of a critical threshold of the serum protein level. PMID:919420

  18. Determination of perfluorinated alkyl acid concentrations in biological standard reference materials.

    PubMed

    Reiner, Jessica L; O'Connell, Steven G; Butt, Craig M; Mabury, Scott A; Small, Jeff M; De Silva, Amila O; Muir, Derek C G; Delinsky, Amy D; Strynar, Mark J; Lindstrom, Andrew B; Reagen, William K; Malinsky, Michelle; Schäfer, Sandra; Kwadijk, Christiaan J A F; Schantz, Michele M; Keller, Jennifer M

    2012-11-01

    Standard reference materials (SRMs) are homogeneous, well-characterized materials used to validate measurements and improve the quality of analytical data. The National Institute of Standards and Technology (NIST) has a wide range of SRMs that have mass fraction values assigned for legacy pollutants. These SRMs can also serve as test materials for method development, method validation, and measurement for contaminants of emerging concern. Because inter-laboratory comparison studies have revealed substantial variability of measurements of perfluoroalkyl acids (PFAAs), future analytical measurements will benefit from determination of consensus values for PFAAs in SRMs to provide a means to demonstrate method-specific performance. To that end, NIST, in collaboration with other groups, has been measuring concentrations of PFAAs in a variety of SRMs. Here we report levels of PFAAs and perfluorooctane sulfonamide (PFOSA) determined in four biological SRMs: fish tissue (SRM 1946 Lake Superior Fish Tissue, SRM 1947 Lake Michigan Fish Tissue), bovine liver (SRM 1577c), and mussel tissue (SRM 2974a). We also report concentrations for three in-house quality-control materials: beluga whale liver, pygmy sperm whale liver, and white-sided dolphin liver. Measurements in SRMs show an array of PFAAs, with perfluorooctane sulfonate (PFOS) being the most frequently detected. Reference and information values are reported for PFAAs measured in these biological SRMs. PMID:22476786

  19. A Rapid Method for Determining the Concentration of Recombinant Protein Secreted from Pichia pastoris

    NASA Astrophysics Data System (ADS)

    Sun, L. W.; Zhao, Y.; Niu, L. P.; Jiang, R.; Song, Y.; Feng, H.; feng, K.; Qi, C.

    2011-02-01

    Pichia secretive expression system is one of powerful eukaryotic expression systems in genetic engineering, which is especially suitable for industrial utilization. Because of the low concentration of the target protein in initial experiment, the methods and conditions for expression of the target protein should be optimized according to the protein yield repetitively. It is necessary to set up a rapid, simple and convenient analysis method for protein expression levels instead of the generally used method such as ultrafiltration, purification, dialysis, lyophilization and so on. In this paper, acetone precipitation method was chosen to concentrate the recombinant protein firstly after comparing with four different protein precipitation methods systematically, and then the protein was analyzed by SDS-Polyacrylamide Gel Electrophoresis. The recombinant protein was determined with the feature of protein band by the Automated Image Capture and 1-D Analysis Software directly. With this method, the optimized expression conditions of basic fibroblast growth factor secreted from pichia were obtained, which is as the same as using traditional methods. Hence, a convenient tool to determine the optimized conditions for the expression of recombinant proteins in Pichia was established.

  20. Improved Strategies and Optimization of Calibration Models for Real-time PCR Absolute Quantification

    EPA Science Inventory

    Real-time PCR absolute quantification applications rely on the use of standard curves to make estimates of DNA target concentrations in unknown samples. Traditional absolute quantification approaches dictate that a standard curve must accompany each experimental run. However, t...

  1. Kidney Function as a Determinant of HDL and Triglyceride Concentrations in the Australian Population

    PubMed Central

    Thompson, Michael; Ray, Udayan; Yu, Richard; Hudspeth, Andrew; Smillie, Michael; Jordan, Neville; Bartle, Janet

    2016-01-01

    Background: Chronic kidney disease (CKD) is a potent risk factor for cardiovascular disease (CVD). CVD risk increases in a stepwise manner with increasing kidney impairment and is significantly reduced by kidney transplantation, suggesting a causal relationship. Dyslipidemia, a well recognised CVD risk factor, is highly prevalent in CKD. While dyslipidemia is a risk factor for CKD, kidney impairment can also induce a dyslipidemic state that may contribute to the excess burden of CVD in CKD. We utilised a multipronged approach to determine whether a causal relationship exists. Materials and Methods: Retrospective case-control analysis of 816 patients admitted to the Royal Hobart Hospital in 2008–2009 with different degrees of kidney impairment and retrospective before-after cohort analysis of 60 patients who received a transplanted kidney between 1999 and 2009. Results: Decreased estimated GFR (eGFR) was independently associated with decreased high density lipoprotein (HDL, p < 0.0001) and increased triglyceride concentrations (p < 0.01) in multivariate analysis. There was no significant relationship between eGFR and low density lipoprotein (LDL) or total cholesterol in multivariate analysis. Kidney transplantation increased HDL (p < 0.0001) and decreased triglyceride (p = 0.007) concentration, whereas there was no significant change in LDL and total cholesterol. These effects were dependent on maintenance of graft function, statin therapy (those who were on) if graft failure occurred then HDL again decreased and triglycerides increased. Conclusions: Kidney transplantation ameliorated alterations in plasma lipoprotein profile associated with kidney impairment, an effect that was dependent on the maintenance of graft function. These data suggest that kidney function is a determinant of HDL and triglyceride concentrations in patients with CKD. PMID:27005668

  2. Absolute oral bioavailability of ciprofloxacin.

    PubMed

    Drusano, G L; Standiford, H C; Plaisance, K; Forrest, A; Leslie, J; Caldwell, J

    1986-09-01

    We evaluated the absolute bioavailability of ciprofloxacin, a new quinoline carboxylic acid, in 12 healthy male volunteers. Doses of 200 mg were given to each of the volunteers in a randomized, crossover manner 1 week apart orally and as a 10-min intravenous infusion. Half-lives (mean +/- standard deviation) for the intravenous and oral administration arms were 4.2 +/- 0.77 and 4.11 +/- 0.74 h, respectively. The serum clearance rate averaged 28.5 +/- 4.7 liters/h per 1.73 m2 for the intravenous administration arm. The renal clearance rate accounted for approximately 60% of the corresponding serum clearance rate and was 16.9 +/- 3.0 liters/h per 1.73 m2 for the intravenous arm and 17.0 +/- 2.86 liters/h per 1.73 m2 for the oral administration arm. Absorption was rapid, with peak concentrations in serum occurring at 0.71 +/- 0.15 h. Bioavailability, defined as the ratio of the area under the curve from 0 h to infinity for the oral to the intravenous dose, was 69 +/- 7%. We conclude that ciprofloxacin is rapidly absorbed and reliably bioavailable in these healthy volunteers. Further studies with ciprofloxacin should be undertaken in target patient populations under actual clinical circumstances. PMID:3777908

  3. Establishment of a real-time RT-PCR for the determination of absolute amounts of IGF-I and IGF-II gene expression in liver and extrahepatic sites of the tilapia.

    PubMed

    Caelers, Antje; Berishvili, Giorgi; Meli, Marina L; Eppler, Elisabeth; Reinecke, Manfred

    2004-06-01

    We developed a one-tube two-temperature real-time RT-PCR that allows to absolutely quantify the gene expression of hormones using the standard curve method. As our research focuses on the expression of the insulin-like growth factors (IGFs) in bony fish, we established the technique for IGF-I and IGF-II using the tilapia (Oreochromis niloticus) as model species. As approach, we used primer extension adding a T7 phage polymerase promoter (21 nt) to the 5' end of the antisense primers. This procedure avoids the disadvantages arising from plasmids. Total RNA extracted from liver was subjected to conventional RT-PCR to create templates for in vitro transcription of IGF-I and IGF-II cRNA. Correct template sizes including the T7 promoter were verified (IGF-I: 91 nt; IGF-II: 94 nt). The PCR products were used to create IGF-I and IGF-II cRNAs which were quantified in dot blot by comparison with defined amounts of standardised kanamycin mRNA. Standardised threshold cycle (Ct) values for IGF-I and IGF-II mRNA were achieved by real-time RT-PCR and used to create standard curves. To allow sample normalisation the standard curve was also established for beta-actin as internal calibrator (template: 86 nt), and validation experiments were performed demonstrating similar amplification efficiencies for target and reference genes. Based on the standard curves, the absolute amounts of IGF-I and IGF-II mRNA were determined for liver (IGF-I: 8.90+/-1.90 pg/microg total RNA, IGF-II: 3.59+/-0.98 pg/microg total RNA) and extrahepatic sites, such as heart, kidney, intestine, spleen, gills, gonad, and brain considering the different lengths of cRNAs and mRNAs by correction factors. The reliability of the method was confirmed in additional experiments. The amplification of descending dilutions of cRNA and total liver RNA resulted in parallel slopes of the amplification curves. Furthermore, amplification plots of the standard cRNA and the IGF-I and IGF-II mRNAs showed signals starting at the

  4. An assay for determining minimal concentrations of antibiotics that drive horizontal transfer of resistance.

    PubMed

    Jutkina, Jekaterina; Rutgersson, Carolin; Flach, Carl-Fredrik; Larsson, D G Joakim

    2016-04-01

    Ability to understand the factors driving horizontal transfer of antibiotic resistance from unknown, harmless bacteria to pathogens is crucial in order to tackle the growing resistance problem. However, current methods to measure effects of stressors on horizontal gene transfer have limitations and often fall short, as the estimated endpoints can be a mix of both the number of transfer events and clonal growth of transconjugants. Our aim was therefore to achieve a proper strategy for assessing the minimal concentration of a stressor (exemplified by tetracycline) that drives horizontal transfer of antibiotic resistance from a complex community to a model pathogen. Conditions were optimized to improve a culture-based approach using the bacterial community of treated sewage effluent as donor, and fluorescent, traceable Escherichia coli as recipient. Reduced level of background resistance, differentiation of isolates as well as decreased risk for measuring effects of selection were achieved through the use of chromogenic medium, optimization of conjugation time as well as applying a different antibiotic for isolation of transconjugants than the one tested for its ability to drive transfer. Using this assay, we showed that a very low concentration of tetracycline, 10μg/L i.e. 150 times below the minimal inhibitory concentration of the recipient, promoted horizontal transfer of multiple antibiotic-resistance determinants. Higher concentrations favoured selection of a tetracycline-resistance phenotype along with a decline in the number of detectable transfer events. The described method can be used to evaluate different environmental conditions and factors that trigger horizontal dissemination of mobile resistance elements, eventually resulting in the formation of drug-resistant pathogens. PMID:26802341

  5. Mixing layer height measurements determines influence of meteorology on air pollutant concentrations in urban area

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Blumenstock, Thomas; Bonn, Boris; Gerwig, Holger; Hase, Frank; Münkel, Christoph; Nothard, Rainer; von Schneidemesser, Erika

    2015-10-01

    Mixing layer height (MLH) is a key parameter to determine the influence of meteorological parameters upon air pollutants such as trace gas species and particulate concentrations near the surface. Meteorology, and MLH as a key parameter, affect the budget of emission source strengths, deposition, and accumulation. However, greater possibilities for the application of MLH data have been identified in recent years. Here, the results of measurements in Berlin in 2014 are shown and discussed. The concentrations of NO, NO2, O3, CO, PM1, PM2.5, PM10 and about 70 volatile organic compounds (anthropogenic and biogenic of origin) as well as particle size distributions and contributions of SOA and soot species to PM were measured at the urban background station of the Berlin air quality network (BLUME) in Nansenstr./Framstr., Berlin-Neukölln. A Vaisala ceilometer CL51, which is a commercial mini-lidar system, was applied at that site to detect the layers of the lower atmosphere in real time. Special software for these ceilometers with MATLAB provided routine retrievals of MLH from vertical profiles of laser backscatter data. Five portable Bruker EM27/SUN FTIR spectrometers were set up around Berlin to detect column averaged abundances of CO2 and CH4 by solar absorption spectrometry. Correlation analyses were used to show the coupling of temporal variations of trace gas compounds and PM with MLH. Significant influences of MLH upon NO, NO2, PM10, PM2.5, PM1 and toluene (marker for traffic emissions) concentrations as well as particle number concentrations in the size modes 70 - 100 nm, 100 - 200 nm and 200 - 500 nm on the basis of averaged diurnal courses were found. Further, MLH was taken as important auxiliary information about the development of the boundary layer during each day of observations, which was required for the proper estimation of CO2 and CH4 source strengths from Berlin on the basis of atmospheric column density measurements.

  6. Prediction of maintenance dose required to attain a desired drug concentration at steady-state from a single determination of concentration after an initial dose.

    PubMed

    Slattery, J T; Gibaldi, M; Koup, J R

    1980-01-01

    Strong correlations have been reported between drug concentrations at steady-state and a single drug concentration determined sometime after an initial dose for lithium, nortriptyline, imipramine, desipramine, choramphenicol and theophylline. The mathematical basis of these relationships suggests that a one point method for predicting steady-state drug concentrations and individual dosing requirements should be widely applicable to most drugs and should be valid for patients having a wide range of drug half-lives. A method is presented for evaluating the optimum time of blood sampling to determine a drug concentration in serum of plasma that best correlates with steady-state levels and for defining the range of drug half-lives beyond which the predictive approach is likely to give poor results. PMID:7398172

  7. Non-Contact Determination of Free Carrier Concentration in n-GaInAsSb

    SciTech Connect

    James E. Maslar; Wildur S. Hurst; Christine A. Wang; Daniel A. Shiau

    2003-11-26

    GaSb-based semiconductors are of interest for mid-infrared optoelectronic and high-speed electronic devices. Accurate determination of electrical properties is essential for optimizing the performance of these devices. However, electrical characterization of these semiconductors is not straightforward since semi-insulating (SI) GaSb substrates for Hall measurements are not available. In this work, the capability of Raman spectroscopy for determination of the majority carrier concentration in n-GaInAsSb epilayers was investigated. Raman spectroscopy offers the advantage of being non-contact and spatially resolved. Furthermore, the type of substrate used for the epilayer does not affect the measurement. However, for antimonide-based materials, traditionally employed Raman laser sources and detectors are not optimized for the analysis wavelength range dictated by the narrow band gap of these materials. Therefore, a near-infrared Raman spectroscopic system, optimized for antimonide-based materials, was developed. Ga{sub 0.85}In{sub 0.15}As{sub 0.13}Sb{sub 0.87} epilayers were grown by organometallic vapor phase epitaxy with doping levels in the range 2 to 80 x 10{sup 17} cm{sup -3}, as measured by secondary ion mass spectrometry. For a particular nominal doping level, epilayers were grown both lattice matched to n-GaSb substrates and lattice-mismatched to SI GaAs substrates under nominally identical conditions. Single magnetic field Hall measurements were performed on the epilayers grown on SI GaAs substrates, while Raman spectroscopy was used to measure the carrier concentration of epilayers grown on GaSb and the corresponding SI GaAs substrates. Compared to Hall measurements, Raman spectra indicated that the GaInAs/Sb epilayers grown on GaSb substrates have higher free carrier concentrations than the corresponding epilayers grown on SI GaAs substrates under nominally identical conditions. This is contrary to the assumption that for nominally identical growth

  8. Determination of nutrients in the presence of high chloride concentrations by column-switching ion chromatography.

    PubMed

    Bruno, P; Caselli, M; de Gennaro, G; De Tommaso, B; Lastella, G; Mastrolitti, S

    2003-06-27

    Determination of inorganic anions in waters of high salinity is one of the most difficult task in analytical chemistry. A simple column-switching method, based on an original chromatographic set-up, for the determination of nutrients (nitrate, nitrite and phosphate) in chloride rich aqueous matrices is presented. A pre-separation system (made of two in line pre-columns, Dionex AG9-HC 4 mm) connected to an analytical column (Dionex AS9-HC 4 mm) by a four way pneumatic valve, allows chloride to be eluted off into the waste and nutrients to be separated and detected by a conductimeter and/or a UV spectrophotometer. Neither chemical pre-treatment nor sample dilution are required; sample matrices presenting a large range of chloride concentrations can be investigated. Moreover by using this technology, automation for routine analysis, low analysis time and low costs can be achieved. LODs of 100, 300, 1000 microg/l for nitrate, nitrite and phosphate, respectively, have been obtained by spiking a synthetic sea water sample containing 20,000 mg/l of chloride and 3000 mg/l of sulphate. Analyte calibration curves of analytes are linear (r>0.99) in the range between the LODs and 60 mg/l. This method was applied to nutrients determination in sea water samples collected near a river outlet. PMID:12899303

  9. Absolute quantification of UGT1A1 in various tissues and cell lines using isotope label-free UPLC-MS/MS method determines its turnover number and correlates with its glucuronidation activities.

    PubMed

    Xu, Beibei; Gao, Song; Wu, Baojian; Yin, Taijun; Hu, Ming

    2014-01-01

    Uridine 5'-diphosphate-glucuronosyltransferase (UGT)1A1 is a major phase II metabolism enzyme responsible for glucuronidation of drugs and endogenous compounds. The purpose of this study was to determine the expression level of UGT1A1 in human liver microsomes and human cell lines by using an isotope label-free LC-MS/MS method. A Waters Ultra performance liquid chromatography (UPLC) system coupled with an API 5500Qtrap mass spectrometer was used for the analysis. Two signature peptides (Pep-1, and Pep-2) were employed to quantify UGT1A1 by multiple reaction monitoring (MRM) approach. Standard addition method was used to validate the assay to account for the matrix effect. 17β-Estradiol was used as the marker substrate to determine UGT1A1 activities. The validated method has a linear range of 200-0.0195nM for both signature peptides. The precision, accuracy, and matrix effect were in acceptable ranges. UGT1A1 expression levels were then determined using 8 individual human liver microsomes, a pooled human liver microsomes, three UGT1A1 genotyped human liver microsomes, and four cell lines (Caco-2, MCF-7, Hela, and HepG2). The correlations study showed that the UGT1A1 protein levels were strongly correlated with its glucuronidation activities in human liver microsomes (R(2)=0.85) and in microsomes prepared from cell lines (R(2)=0.95). Isotope-labeled peptides were not necessary for LC-MS/MS quantitation of proteins. The isotope label-free absolute quantification method used here had good accuracy, sensitivity, linear range, and reproducibility, and were used successfully for the accurate determination of UGT1A1 from tissues and cell lines. PMID:24055854

  10. Determining concentration fields of tracer plumes for layered porous media in flow-tank experiments

    NASA Astrophysics Data System (ADS)

    Yu, Zhongbo; Schwartz, Franklin W.

    In the laboratory, computer-assisted image analysis provides an accurate and efficient way to monitor tracer experiments. This paper describes the determination of detailed temporal concentration distributions of tracers in a flow-tank experiment by analyzing photographs of plumes of Rhodamine dye through the glass wall of the tank. The methodology developed for this purpose consists of four steps: (1) digitally scanning black and white negatives obtained from photographs of the flow-tank experiment; (2) calibrating and normalizing each digitized image to a standard optical-density scale by determining the relation between the optical density and pixel value for each image; (3) constructing standard curves relating the concentration in an optical density from five experimental runs with predetermined concentrations (2-97mg/L) and (4) converting the optical density to concentration. The spatial distribution of concentration for two photographs was determined by applying these calibration and conversion procedures to all pixels of the digitized images. This approach provides an efficient way to study patterns of plume evolution and transport mechanisms. Résumé Au laboratoire, l'analyse d'images assistée par ordinateur est un moyen précis et efficace pour suivre certaines expériences de traçage. Ce papier présente comment sont déterminées dans le détail les distributions temporelles de la concentration en traceur au cours d'une expérience d'écoulement en réservoir au moyen de l'analyse de photographies de panaches de rhodamine à travers la paroi de verre du réservoir. La méthodologie développée dans cette expérience suit quatre étapes: (1) digitalisation par balayage des négatifs noir et blanc des prises de vue de l'expérience d'écoulement en réservoir (2) calibration et normalisation de chaque image digitalisée par rapport à une échelle étalon de densité optique en déterminant la relation entre la densité optique et la valeur des pixels

  11. Rapid and quantitative determination of critical micelle concentration by automatic continuous mixing and static light scattering.

    PubMed

    Paillet, Sabrina; Grassl, Bruno; Desbrières, Jacques

    2009-03-23

    We present the rapid and quantitative characterization of ionic, non-ionic and zwitterionic surfactants based upon the combination of an automatic continuous mixing technique and static light scattering. Collection and subsequent analysis of data are both rapid and semiautomatic, which increases precision, sensitivity, and range of applicability while substantially decreasing the amount of manual intervention required by the investigator. By treating the continuous data, the entire data set may be rapidly analyzed in the context of the closed association model to determine the critical micelle concentration cmc and aggregation number Nag of a detergent; these technique are comparable in the scope and resolution currently obtainable from other conductimetric, fluorescence and surface tension techniques. PMID:19264174

  12. Method and system for fiber optic determination of gas concentrations in liquid receptacles

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet (Inventor)

    2008-01-01

    A system for determining gas compositions includes a probe, inserted into a source of gaseous material, the probe having a gas permeable sensor tip and being capable of sending and receiving light to and from the gaseous material, a sensor body, connected to the probe, situated outside of the source and a fiber bundle, connected to the sensor body and communicating light to and from the probe. The system also includes a laser source, connected to one portion of the fiber bundle and providing laser light to the fiber bundle and the probe a Raman spectrograph, connected to another portion of the fiber bundle, receiving light from the probe and filtering the received light into specific channels and a data processing unit, receiving and analyzing the received light in the specific channels and outputting concentration of specific gas species in the gaseous material based on the analyzed received light.

  13. Determination of the low concentration correction in the macroscopic singlet oxygen model for PDT

    NASA Astrophysics Data System (ADS)

    Kim, Michele M.; Penjweini, Rozhin; Finlay, Jarod C.; Zhu, Timothy C.

    2016-03-01

    The macroscopic singlet oxygen model has been used for singlet oxygen explicit dosimetry in photodynamic therapy (PDT). The photophysical parameters for commonly used sensitizers, HPPH and BPD, have been investigated in pre-clinical studies using mouse models. So far, studies have involved optimizing fitting algorithms to obtain the some of the photophysical parameters (ξ, σ, g) and the threshold singlet oxygen dose ([1O2]rx,sh), while other parameters such as the low concentration correction, δ, has been kept as a constant. In this study, using photobleaching measurements of mice in vivo, the value of δ was also optimized and fit to better describe experimental data. Furthermore, the value of the specific photobleaching ratio (σ) was also fine-tuned using the photobleaching results. Based on literature values of δ, σ for photosensitizers can be uniquely determined using the additional photobleaching measurements. This routine will further improve the macroscopic model of singlet oxygen production for use in explicit dosimetry.

  14. Determination of the concentration and isotopic composition of uranium in environmental air filters

    SciTech Connect

    Russ, G.P. III; Bazan, J.M.

    1994-08-26

    For many years, Lawrence Livermore National Laboratory has collected monthly air-particulate filter samples from a variety of environmental monitoring stations on and off site. Historically the concentration and isotopic composition of uranium collected on these filters was determined by isotope dilution using a {sup 233}U spike and thermal ionization mass spectrometry (TIMS). For samples containing as little as 10 nanograms of uranium, ICP-MS is now used to make these measurements to the required level of precision, about 5% in the measured 235/238 and 233/238. Unless particular care is taken to control bias in the mass filter, variable mass bias limits accuracy to a few percent. Measurements of the minor isotopes 236 (if present) and 234 are also possible and provide useful information for identifying the source of the uranium. The advantage of ICP-MS is in rapid analysis, {approximately}12 minutes of instrument time per sample.

  15. A rapid method to determine sterol, erythrodiol, and uvaol concentrations in olive oil.

    PubMed

    Mathison, Brian; Holstege, Dirk

    2013-05-15

    A rapid, accurate, and efficient method for determining the sterol, uvaol, and erythrodiol concentrations was developed to meet International Olive Council (IOC) certification criteria for extra virgin olive oil (EVOO). The unsaponifiable fraction of the sample (0.2 g) was separated with a diatomaceous earth column, and the sterol and triterpenic dialcohols were isolated with a novel base-activated silica solid-phase extraction (SPE) cartridge cleanup protocol. The improved method and the IOC method provided identical pass/fail results (n = 34) for each of the six sterol and erythrodiol/uvaol IOC criteria used to assess olive oil. This method was validated, and recoveries of stigmasterol (88%) and β-sitosterol (84%) were greater than previously published values obtained using the IOC method. This method requires approximately one-third the time required to complete the IOC method and has great utility for the rapid screening of EVOO to detect adulteration, false labeling, and an inferior product. PMID:23587059

  16. Non-destructive determination of trace-element concentrations. Annual progress report

    SciTech Connect

    Gordon, G.E.; Zoller, W.H.; Walters, W.B.

    1980-08-01

    In this year's Report, the neutron-capture prompt ..gamma..-ray activation analysis (PGAA) for trace-element concentrations was used in several new types of samples such as: volcanic samples which included yellow deposits found near volcanoes, fresh ash samples, and suspended particles in plumes from Mt. St. Helens with aircraft; energy related samples which were coal, coal fly ash, oil shale, shale oil and oil; biological samples of freeze-dried blood and liver; neutron-capture cross-sections of borehole samples; and boron in semiconductor silicon. The report includes recommended ..gamma..-ray lines for quantitative determinations, systems improvements of the beam filter system, second sample position and data handling facilities.

  17. Radiometric method for determining concentration of naturally occurring isotopes and device therefor

    SciTech Connect

    Yakubovich, S.L.; Gerling, V.E.; Golubnichy, V.V.; Kotsen, M.E.; Stepanov, J.N.

    1984-10-09

    The proposed method essentially consists in that a sample of a substance is placed between two scintillators in immediate contact therewith whereupon said sample is hermetically sealed. Arranged in close proximity to each scintillator is a photomultiplier tube recording ionizing ..cap alpha..- and b-radiation. A selector is utilized to select pulses corresponding to ..cap alpha..- and b-particles, and delayed coincidence circuits of a recording element separate and record b-..cap alpha.. and ..cap alpha..-..cap alpha.. cascade pairs of delayed coincidences of RaC, ThC, and AcA radionuclides. Flows are measured twice at a predetermined time interval to account for emanation build-up tendency and concentration of isotopes of radium is determined from a formula.

  18. Rapid method for determining concentrations of Bayer 73 in water during lampricide treatments

    USGS Publications Warehouse

    Dawson, V.K.; Harman, P.D.; Schultz, D.P.; Allen, J.L.

    1978-01-01

    Two simple, rapid, sensitive methods were developed for determining the concentration of the lampricide 2',5-dichloro-4'-nitrosalicylanilide (Bayer 73) in stream water. Bayer 73 was extracted from acidified water samples with chloroform and then hydrolyzed to 2-chloro-4-nitroaniline (CNA) with either acid or base. The CNA was diazotized with sodium nitrite, and an azo dye was formed with either N-( 1-naphthyl) ethylenediamine dihydrochloride (after acid hydrolysis) or 1-naphthol (after base hydrolysis). There was no interference from the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) in either method. Standard curves were prepared with untreated water to compensate for interfering substances that occurred naturally in some streams. The methods were sensitive to about 0.005 mg/L (ppm). Time required for analysis of a sample ranged from 25 min to 1 h.

  19. A convenient fluorescent method to simultaneously determine the enantiomeric composition and concentration of functional chiral amines.

    PubMed

    Huang, Zeng; Yu, Shanshan; Zhao, Xue; Wen, Kaili; Xu, Yimang; Yu, Xiaoqi; Xu, Yong; Pu, Lin

    2014-12-01

    A 1,1'-bi-2-naphthol (BINOL)-based chiral aldehyde in combination with Zn(II) shows a highly enantioselective fluorescent response toward functional chiral amines at λ>500 nm. However, the combination of salicylaldehyde and Zn(II) gives the same fluorescent enhancement for both enantiomers of a functional chiral amine at λ=447 nm. By using the fluorescent responses of the combination of the BINOL-based chiral aldehyde, salicylaldehyde and Zn(II) at the two emission wavelengths, both the concentration and enantiomeric composition of functional chiral amines such as amino alcohols, diamines, and amino acids can be simultaneously determined by a single fluorescent measurement. This work provides a simple and convenient method for chiral assay. PMID:25348091

  20. Interferences of resveratrol with fura-2-derived fluorescence in intracellular free-Ca(2+) concentration determinations.

    PubMed

    Santofimia-Castaño, Patricia; Salido, Gines M; Gonzalez, Antonio

    2016-08-01

    Resveratrol (3,4',5-trihydroxy-trans-stilbene) is an antioxidant widely employed in cell physiology studies. It has been reported that it interferes with fura-2-derived fluorescence, making the employment of this dye nonviable. In this work, the interference of resveratrol with fura-2 determinations of intracellular free-Ca(2+) concentration ([Ca(2+)]c) was examined. Solutions containing different concentrations of resveratrol, with or without fura-2, in the presence or in the absence of Ca(2+), were analyzed by spectrofluorimetry. AR42J tumor cells were employed to study the influence of resveratrol on fura-2 fluorescence in living cells, by single cell fluorimetry. Resveratrol impaired the detection of fura-2-fluorescence emission (510 nm) at the 340, 360 and 380 nm excitation wavelengths. Resveratrol emitted fluorescence at 510 nm when lighted at all three excitation wavelengths. In addition, resveratrol emitted fluorescence at 380 nm when excited at 340 nm. Our observations suggest that the employment of the ratiometric properties of fura-2 to follow changes in [Ca(2+)]c in the presence of resveratrol is not viable. However, we think that the 380 nm excitation light could be employed. Results could be expressed as F0/F380, where F0 is the resting fluorescence and F380 is the value of fluoresce at a certain time point. We could follow changes in [Ca(2+)]c evoked by CCK-8, and we also detected Ca(2+) mobilization by 100 µM resveratrol in AR42J cells. This investigation presents evidence demonstrating that resveratrol interferes with fura-2 fluorescence spectra. Nevertheless, a chance still exists if the 380 nm excitation wavelength is employed in the middle or low micromolar concentrations of resveratrol. PMID:26091617

  1. Pollutant threshold concentration determination in marine ecosystems using an ecological interaction endpoint.

    PubMed

    Wang, Changyou; Liang, Shengkang; Guo, Wenting; Yu, Hua; Xing, Wenhui

    2015-09-01

    The threshold concentrations of pollutants are determined by extrapolating single-species effect data to community-level effects. This assumes the most sensitive endpoint of the life cycle of individuals and the species sensitivity distribution from single-species toxic effect tests, thus, ignoring the ecological interactions. The uncertainties due to this extrapolation can be partially overcome using the equilibrium point of a customized ecosystem. This method incorporates ecological interactions and integrates the effects on growth, survival, and ingestion into a single effect measure, the equilibrium point excursion in the customized ecosystem, in order to describe the toxic effects on plankton. A case study showed that the threshold concentration of copper calculated with the endpoint of the equilibrium point was 10 μg L(-1), which is significantly different from the threshold calculated with a single-species endpoint. The endpoint calculated using this method provides a more relevant measure of the ecological impact than any single individual-level endpoint. PMID:25982547

  2. Transient Method for Determining Indoor Chemical Concentrations Based on SPME: Model Development and Calibration.

    PubMed

    Cao, Jianping; Xiong, Jianyin; Wang, Lixin; Xu, Ying; Zhang, Yinping

    2016-09-01

    Solid-phase microextraction (SPME) is regarded as a nonexhaustive sampling technique with a smaller extraction volume and a shorter extraction time than traditional sampling techniques and is hence widely used. The SPME sampling process is affected by the convection or diffusion effect along the coating surface, but this factor has seldom been studied. This paper derives an analytical model to characterize SPME sampling for semivolatile organic compounds (SVOCs) as well as for volatile organic compounds (VOCs) by considering the surface mass transfer process. Using this model, the chemical concentrations in a sample matrix can be conveniently calculated. In addition, the model can be used to determine the characteristic parameters (partition coefficient and diffusion coefficient) for typical SPME chemical samplings (SPME calibration). Experiments using SPME samplings of two typical SVOCs, dibutyl phthalate (DBP) in sealed chamber and di(2-ethylhexyl) phthalate (DEHP) in ventilated chamber, were performed to measure the two characteristic parameters. The experimental results demonstrated the effectiveness of the model and calibration method. Experimental data from the literature (VOCs sampled by SPME) were used to further validate the model. This study should prove useful for relatively rapid quantification of concentrations of different chemicals in various circumstances with SPME. PMID:27476381

  3. Photoacoustic determination of glucose concentration in whole blood by a near-infrared laser diode

    NASA Astrophysics Data System (ADS)

    Zhao, Zuomin; Myllylae, Risto A.

    2001-06-01

    The near-infrared photoacoustic technique is recognized as a potential method for the non-invasive determination of human glucose, because near-infrared light can incident a few millimeters into human tissue, where it produces an acoustic wave capable of carrying information about the composition of the tissue. This paper demonstrates a photoacoustic glucose measurement in a blood sample as a step toward a non-invasive measurement. The experimental apparatus consists of a near-infrared laser diode operating with 4 micro joules pulse energy at 905 nm, a roller pump connected to a silicon plastic tube and a cuvette for circulating the blood sample. In addition, the apparatus comprises a PZT piezoelectric transducer integrated with a battery-powered preamplifier to receive the photoacoustic signal. During the experiment, a glucose solution is mixed into a human blood sample to change its concentration. Although the absorption coefficient of glucose is much smaller than that of blood in the near-infrared region, the osmotic and hydrophilic properties of glucose decrease the reduced scattering coefficient of blood caused by the dissolved glucose surrounding the blood cells. This changes the distribution of the absorbed optical energy in blood, which, in turn, produces a change in the photoacoustic signal. Our experiment demonstrates that signal amplitudes in fresh and stored blood samples in crease about 7% and 10%, respectively, when the glucose concentration reaches the upper limit of the physiological region (500 mg/dl).

  4. Liquid chromatographic method for determining the concentration of bisazir in water

    USGS Publications Warehouse

    Scholefield, Ronald J.; Slaght, Karen S.; Allen, John L.

    1997-01-01

    Barrier dams, traps, and lampricides are the techniques currently used by the Great Lakes Fishery Commission to control sea lampreys (Petromyzon marinus) in the Great Lakes. To augment these control techniques, a sterile-male-release research program was initiated at the Lake Huron Biological Station. Male sea lampreys were sterilized by intraperitoneal injection of the chemical sterilant P,P-bis(1-aziridinyl)-N-methylphosphinothioic amide (bisazir). An analytical method was needed to quantitate the concentration of bisazir in water and to routinely verify that bisazir (>25 μg/L) does not persist in the treated effluent discharged from the sterilization facility to Lake Huron. A rapid, accurate, and sensitive liquid chromatographic (LC) method was developed for determining bisazir in water. Bisazir was dissolved in Lake Huron water; extracted and concentrated on a C18 solid-phase extraction column; eluted with methanol; and quantitated by reversed-phase LC using a C18 column, a mobile phase of 70% water and 30% methanol (v/v), and UV detection (205 nm). Bisazir retention time was 7-8 min; total run time was about 20 min. Method detection limit for bisazir dissolved in Lake Huron water was about 15 μg/L. Recovery from Lake Huron water fortified with bisazir at 100 μg/L was 94% (95% confidence interval, 90.2-98.2%).

  5. Advances towards reliable identification and concentration determination of rare cells in peripheral blood

    NASA Astrophysics Data System (ADS)

    Alemany Server, R.; Martens, D.; Jans, K.; Bienstman, P.; Hill, D.

    2016-03-01

    Through further development, integration and validation of micro-nano-bio and biophotonics systems FP7 CanDo is developing an instrument that will permit highly reproducible and reliable identification and concentration determination of rare cells in peripheral blood for two key societal challenges, early and low cost anti-cancer drug efficacy determination and cancer diagnosis/monitoring. A cellular link between the primary malignant tumour and the peripheral metastases, responsible for 90% of cancerrelated deaths, has been established in the form of circulating tumour cells (CTCs) in peripheral blood. Furthermore, the relatively short survival time of CTCs in peripheral blood means that their detection is indicative of tumour progression thereby providing in addition to a prognostic value an evaluation of therapeutic efficacy and early recognition of tumour progression in theranostics. In cancer patients however blood concentrations are very low (=1 CTC/1E9 cells) and current detection strategies are too insensitive, limiting use to prognosis of only those with advanced metastatic cancer. Similarly, problems occur in therapeutics with anti-cancer drug development leading to lengthy and costly trials often preventing access to market. The novel cell separation/Raman analysis technologies plus nucleic acid based molecular characterization of the CanDo platform will provide an accurate CTC count with high throughput and high yield meeting both key societal challenges. Being beyond the state of art it will lead to substantial share gains not just in the high end markets of drug discovery and cancer diagnostics but due to modular technologies also in others. Here we present preliminary DNA hybridization sensing results.

  6. Methane emission from naturally ventilated livestock buildings can be determined from gas concentration measurements.

    PubMed

    Bjerg, Bjarne; Zhang, Guoqiang; Madsen, Jørgen; Rom, Hans B

    2012-10-01

    Determination of emission of contaminant gases as ammonia, methane, or laughing gas from natural ventilated livestock buildings with large opening is a challenge due to the large variations in gas concentration and air velocity in the openings. The close relation between calculated animal heat production and the carbon dioxide production from the animals have in several cases been utilized for estimation of the ventilation air exchange rate for the estimation of ammonia and greenhouse gas emissions. Using this method, the problem of the complicated air velocity and concentration distribution in the openings is avoided; however, there are still some important issues remained unanswered: (1) the precision of the estimations, (2) the requirement for the length of measuring periods, and (3) the required measuring point number and location. The purpose of this work was to investigate how estimated average gas emission and the precision of the estimation are influenced by different calculation procedures, measuring period length, measure point locations, measure point numbers, and criteria for excluding measuring data. The analyses were based on existing data from a 6-day measuring period in a naturally ventilated, 150 milking cow building. The results showed that the methane emission can be determined with much higher precision than ammonia or laughing gas emissions, and, for methane, relatively precise estimations can be based on measure periods as short as 3 h. This result makes it feasible to investigate the influence of feed composition on methane emission in a relative large number of operating cattle buildings and consequently it can support a development towards reduced greenhouse gas emission from cattle production. PMID:22020391

  7. Improving HST Pointing & Absolute Astrometry

    NASA Astrophysics Data System (ADS)

    Lallo, Matthew; Nelan, E.; Kimmer, E.; Cox, C.; Casertano, S.

    2007-05-01

    Accurate absolute astrometry is becoming increasingly important in an era of multi-mission archives and virtual observatories. Hubble Space Telescope's (HST's) Guidestar Catalog II (GSC2) has reduced coordinate error to around 0.25 arcsecond, a factor 2 or more compared with GSC1. With this reduced catalog error, special attention must be given to calibrate and maintain the Fine Guidance Sensors (FGSs) and Science Instruments (SIs) alignments in HST to a level well below this in order to ensure that the accuracy of science product's astrometry keywords and target positioning are limited only by the catalog errors. After HST Servicing Mission 4, such calibrations' improvement in "blind" pointing accuracy will allow for more efficient COS acquisitions. Multiple SIs and FGSs each have their own footprints in the spatially shared HST focal plane. It is the small changes over time in primarily the whole-body positions & orientations of these instruments & guiders relative to one another that is addressed by this work. We describe the HST Cycle 15 program CAL/OTA 11021 which, along with future variants of it, determines and maintains positions and orientations of the SIs and FGSs to better than 50 milli- arcseconds and 0.04 to 0.004 degrees of roll, putting errors associated with the alignment sufficiently below GSC2 errors. We present recent alignment results and assess their errors, illustrate trends, and describe where and how the observer sees benefit from these calibrations when using HST.

  8. Absolute linestrengths in the H2O2 nu6 band

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1991-01-01

    Absolute linestrengths at 295 K have been measured for selected lines in the nu6 band of H2O2 using a tunable diode-laser spectrometer. H2O2 concentrations in a flowing gas mixture were determined by ultraviolet (uv) absorption at 254 nm using a collinear infrared (ir) and uv optical arrangement. The measured linestrengths are approx. 60 percent larger than previously reported values when absorption by hot bands in H2O2 is taken into account.

  9. Determination of the absolute configuration of chiral α-aryloxypropanoic acids using vibrational circular dichroism studies: 2-(2-chlorophenoxy) propanoic acid and 2-(3-chlorophenoxy) propanoic acid

    NASA Astrophysics Data System (ADS)

    He, Jiangtao; Polavarapu, Prasad L.

    2005-05-01

    The enantiomers of 2-(2-chlorophenoxy) propanoic acid and 2-(3-chlorophenoxy) propanoic acid were resolved on a chiral HPLC column and investigated using mid-infrared vibrational circular dichroism (VCD). Experimental infrared vibrational absorption and VCD spectra were measured in CDCl 3 solution in the 2000-900 cm -1 region and compared with the ab initio predictions of absorption and VCD spectra. The predicted spectra were obtained with density functional theory using B3LYP/6-31G* basis set for the stable and dominant conformers. But the predicted spectra did not provide unambiguous structural information due to intermolecular hydrogen bonding in solution. To eliminate the hydrogen bonding effects, the acids were converted to the corresponding methyl esters and the experimental absorbance and VCD spectra of methyl esters were measured. B3LYP predicted spectra were also obtained for the stable and dominant conformers of the esters. From a comparison of the experimental VCD spectra of methyl esters with corresponding ab initio predictions, the absolute configurations of esters, and therefore of their parent acids, are unambiguously determined to be (+)-( R).

  10. Determination of lipoprotein(a) concentrations and apolipoprotein(a) molecular weights in diabetic patients.

    PubMed

    Ribault, A; Durou, M R; Letellier, C; Wojcik, F; Poirier, J Y; Ruelland, A

    2000-04-01

    Lipoprotein(a) (Lp(a)) with atherogenic and thrombotic properties has been frequently studied in diabetes, because a high cardiovascular risk has been reported both in type 1 and type 2 diabetes. Few studies have considered genetic factors, especially the isoforms of apolipoprotein(a). The aim of this work is to determine the distribution of apo(a) phenotypes in the serum of 148 diabetic patients (59 type 1, 89 type 2) with or without vascular complications. Apo(a) phenotypes are determined using 4-15% sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by immunoblotting (PhastSystem - Pharmacia). An inverse relationship is observed between Lp(a) serum concentration and the apparent molecular mass of apo(a) isoforms: type 1 r=- 0.61, p<0.01; type 2 r=- 0.55, p<0.01. The frequency of apo(a) isoforms is significantly different between type 1 and type 2 diabetes mellitus. A higher prevalence of isoforms of low molecular weight was observed in the type 2 diabetic population. PMID:10804324

  11. Human haptoglobin phenotypes and concentration determination by nanogold-enhanced electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Tsai-Mu; Lee, Tzu-Cheng; Tseng, Shin-Hua; Chu, Hsueh-Liang; Pan, Ju-Pin; Chang, Chia-Ching

    2011-06-01

    Haptoglobin (Hp) is an acute phase protein that binds free hemoglobin (Hb), preventing Hb-induced oxidative damage in the vascular system. There are three phenotypes in human Hp, whose heterogeneous polymorphic structures and varying concentrations in plasma have been attributed to the cause of diseases and outcome of clinical treatments. Different phenotypes of Hp may be composed of the same subunits but different copy numbers, rendering their determination difficult by a single procedure. In this study, we have developed a simple, fast, reliable and sensitive method, using label-free nanogold-modified bioprobes coupled with self-development electrochemical impedance spectroscopy (EIS). By this method, probe surface charge transfer resistance is detected. The relative charge transfer resistance ratios for Hp 1-1, Hp 2-1 and Hp 2-2 were characterized. We were able to determine protein size difference within 3 nm, and the linear region of the calibration curve for Hp levels in the range of 90 pg ml - 1 and 90 µg ml - 1 (~1 fM to 1 pM). We surmise that similar approaches can be used to investigate protein polymorphism and altered protein-protein interaction associated with diseases.

  12. Redetermining CEBAF's Absolute Energy

    NASA Astrophysics Data System (ADS)

    Su, Tong; Jlab Marathon Collaboration

    2015-04-01

    With the upgrade of the Jefferson Lab accelerator (CEBAF) from 6 GeV max energy to 12 GeV, all the dipole magnets in the machine were refurbished. Most of them were switched from open c-shaped to closed h-shaped by adding extra iron. With these upgraded magnets, the energy calibration of the accelerator needed to be redetermined. We will show how an extra external dipole, which is run in series with those in the machine, helps us cross check the current in the magnets as well as precisely map out the integral field for any machine setting. Using knowledge of the relative performance of the dipoles as well as the bend angle into the Hall, has allowed us to already determine a 4th pass 7 GeV beam to better than 7 MeV. In the future, we will use g-2 spin precession as a second independent energy determination. This work is supported by Kent State University, NSF Grant PHY-1405814, and DOE Contract DE-AC05-06OR23177 (JLab).

  13. On Using Model Populations to Determine Mechanical Properties of Skeletal Muscle. Application to Concentric Contraction Simulation.

    PubMed

    Sierra, M; Miana-Mena, F J; Calvo, B; Muñoz, M J; Rodríguez, J F; Grasa, J

    2015-10-01

    In the field of computational biomechanics, the experimental evaluation of the material properties is crucial for the development of computational models that closely reproduce real organ systems. When simulations of muscle tissue are concerned, stress/strain relations for both passive and active behavior are required. These experimental relations usually exhibit certain variability. In this study, a set of material parameters involved in a 3D skeletal muscle model are determined by using a system biology approach in which the parameters are randomly varied leading to a population of models. Using a set of experimental results from an animal model, a subset of the entire population of models was selected. This reduced population predicted the mechanical response within the window of experimental observations. Hence, a range of model parameters, instead of a single set of them, was determined. Rat Tibialis Anterior muscle was selected for this study. Muscles ([Formula: see text]) were activated through the sciatic nerve and during contraction the tissue pulled a weight fixed to the distal tendon (concentric contraction). Three different weights 1, 2 and 3 N were used and the time course of muscle stretch was analyzed obtaining values of (mean [Formula: see text] standard deviation): [Formula: see text], [Formula: see text] and [Formula: see text] respectively. A paired two-sided sign rank test showed significant differences between the muscle response for the three weights ([Formula: see text]). This study shows that the Monte Carlo method could be used for determine muscle characteristic parameters considering the variability of the experimental population. PMID:25691399

  14. Testing the quasi-absolute method in photon activation analysis

    SciTech Connect

    Sun, Z. J.; Wells, D.; Starovoitova, V.; Segebade, C.

    2013-04-19

    In photon activation analysis (PAA), relative methods are widely used because of their accuracy and precision. Absolute methods, which are conducted without any assistance from calibration materials, are seldom applied for the difficulty in obtaining photon flux in measurements. This research is an attempt to perform a new absolute approach in PAA - quasi-absolute method - by retrieving photon flux in the sample through Monte Carlo simulation. With simulated photon flux and database of experimental cross sections, it is possible to calculate the concentration of target elements in the sample directly. The QA/QC procedures to solidify the research are discussed in detail. Our results show that the accuracy of the method for certain elements is close to a useful level in practice. Furthermore, the future results from the quasi-absolute method can also serve as a validation technique for experimental data on cross sections. The quasi-absolute method looks promising.

  15. Metallic Magnetic Calorimeters for Absolute Activity Measurement

    NASA Astrophysics Data System (ADS)

    Loidl, M.; Leblanc, E.; Rodrigues, M.; Bouchard, J.; Censier, B.; Branger, T.; Lacour, D.

    2008-05-01

    We present a prototype of metallic magnetic calorimeters that we are developing for absolute activity measurements of low energy emitting radionuclides. We give a detailed description of the realization of the prototype, containing an 55Fe source inside the detector absorber. We present the analysis of first data taken with this detector and compare the result of activity measurement with liquid scintillation counting. We also propose some ways for reducing the uncertainty on the activity determination with this new technique.

  16. Absolute distance measurements by variable wavelength interferometry

    NASA Astrophysics Data System (ADS)

    Bien, F.; Camac, M.; Caulfield, H. J.; Ezekiel, S.

    1981-02-01

    This paper describes a laser interferometer which provides absolute distance measurements using tunable lasers. An active feedback loop system, in which the laser frequency is locked to the optical path length difference of the interferometer, is used to tune the laser wavelengths. If the two wavelengths are very close, electronic frequency counters can be used to measure the beat frequency between the two laser frequencies and thus to determine the optical path difference between the two legs of the interferometer.

  17. Absolute dosimetry for extreme-ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Berger, Kurt W.; Campiotti, Richard H.

    2000-06-01

    The accurate measurement of an exposure dose reaching the wafer on an extreme ultraviolet (EUV) lithographic system has been a technical challenge directly applicable to the evaluation of candidate EUV resist materials and calculating lithography system throughputs. We have developed a dose monitoring sensor system that can directly measure EUV intensities at the wafer plane of a prototype EUV lithographic system. This sensor system, located on the wafer stage adjacent to the electrostatic chuck used to grip wafers, operates by translating the sensor into the aerial image, typically illuminating an 'open' (unpatterned) area on the reticle. The absolute signal strength can be related to energy density at the wafer, and thus used to determine resist sensitivity, and the signal as a function of position can be used to determine illumination uniformity at the wafer plane. Spectral filtering to enhance the detection of 13.4 nm radiation was incorporated into the sensor. Other critical design parameters include the packaging and amplification technologies required to place this device into the space and vacuum constraints of a EUV lithography environment. We describe two approaches used to determine the absolute calibration of this sensor. The first conventional approach requires separate characterization of each element of the sensor. A second novel approach uses x-ray emission from a mildly radioactive iron source to calibrate the absolute response of the entire sensor system (detector and electronics) in a single measurement.

  18. HIV-1 resistance to neutralizing antibodies: Determination of antibody concentrations leading to escape mutant evolution.

    PubMed

    Magnus, Carsten; Reh, Lucia; Trkola, Alexandra

    2016-06-15

    Broadly neutralizing antibodies against human immunodeficiency virus type 1 (HIV-1) are considered vital components of novel therapeutics and blueprints for vaccine research. Yet escape to even the most potent of these antibodies is imminent in natural infection. Measures to define antibody efficacy and prevent mutant selection are thus urgently needed. Here, we derive a mathematical framework to predict the concentration ranges for which antibody escape variants can outcompete their viral ancestors, referred to as mutant selection window (MSW). When determining the MSW, we focus on the differential efficacy of neutralizing antibodies against HIV-1 in two canonical infection routes, free-virus infection and cell-cell transmission. The latter has proven highly effective in vitro suggesting its importance for both in vivo spread as well as for escaping targeted intervention strategies. We observed a range of MSW patterns that highlight the potential of mutants to arise in both transmission pathways and over wide concentration ranges. Most importantly, we found that only when the arising mutant has both, residual sensitivity to the neutralizing antibody and reduced infectivity compared to the parental virus, antibody dosing outside of the MSW to restrict mutant selection is possible. Emergence of mutants that provide complete escape and have no considerable fitness loss cannot be prevented by adjusting antibody doses. The latter may in part explain the ubiquitous resistance to neutralizing antibodies observed in natural infection and antibody treatment. Based on our findings, combinations of antibodies targeting different epitopes should be favored for antibody-based interventions as this may render complete resistance less likely to occur and also increase chances that multiple escapes result in severe fitness loss of the virus making longer-term antibody treatment more feasible. PMID:26494166

  19. Utilizing an open-microcavity optoacoustic sensor for spectroscopic determination of methemoglobin concentration

    NASA Astrophysics Data System (ADS)

    Peterson, Ralph W.; Kadugodinandareddy, Kavya; Karunakaran, Vinitha; Whitney, Casey; Ling, Jian; Ye, Jing Yong

    2015-03-01

    We present a simple, non-destructive photoacoustic spectroscopy method utilizing a unique open-microcavity optoacoustic sensor to measure the concentration ratio of Methemoglobin (MetHb) in an optically scattering medium. Elevated levels of MetHb, present for example in the blood disorder Methemeglobinemia, cannot be detected by conventional pulse oximetry, and may result in inaccurate arterial oxygen saturation measurements. Samples with different ratios of Oxygenated Hemoglobin (HbO2), Deoxygenated Hemoglobin (HHb), and MetHb were obtained and mixed with nanoscale latex beads to present an optical scattering effect. Polymer encapsulated hemoglobin (PEH) samples were also studied. A sample chamber containing 20 μL of each sample was positioned directly underneath our patented optoacoustic sensor. Unlike a piezoelectric transducer, our optoacoustic sensor allows an excitation laser beam from an OPO laser to pass through and be absorbed by the sample to produce a photoacoustic signal. The cavity layer of the optoacoustic sensor is exposed directly to the resulting ultrasound signal, which causes an intensity modulation of a HeNe laser that is used to monitor the resonance condition of the sensor. A probe laser beam is total internally reflected off of the sensor and detected with a fiber-coupled APD detector. Three wavelengths are chosen for our excitation laser based on the absorption peaks and isobestic points of HHb, HbO2, and MetHb. Using established values of the molar extinction coefficients of HbO2, HHb, and MetHb a set of three simultaneous equations can be solved to accurately determine the concentration ratio of MetHb.

  20. Determining the kinetics and concentrations of singlet molecular oxygen on natural snow

    NASA Astrophysics Data System (ADS)

    Bower, J. P.; Anastasio, C.

    2008-12-01

    Singlet molecular oxygen (1O2*), the first electronically excited state of molecular oxygen, reacts rapidly with several classes of environmental pollutants such as furans, phenols, and polycyclic aromatic hydrocarbons (PAHs). Its formation requires the absorption of light by a chromophore (a.k.a. sensitizer), which subsequently transfers energy to ground state molecular oxygen. In prior work, we have shown that the rate of formation (Rf) and steady state concentration ([1O2*]) of 1O2* can be orders of magnitude higher in frozen ice relative to the same laboratory solution studied as a liquid. Here we discuss how we have modified our method to determine Rf and [1O2*] on natural snow, which required overcoming several difficulties: the total solute concentrations are low, the 1O2* sensitizing species are unknown, and other oxidants could be interfering with the measured loss of our chemical probe. The new method is similar to the one used previously, as both use furfuryl alcohol (FFA) as a probe for photoformed 1O2*. The total rate of FFA decay is the sum of its direct photolysis and the rate of all its reactions with other species. Introducing a sink for other oxidants and taking the difference between this measured decay rate and the rate of direct photolysis yields the rate of decay due specifically 1O2*. As a second validation, experiments were also conducted in D2O. In liquid solution, water is the dominant sink for 1O2* where physical quenching controls the lifetime, and thus the steady state concentration, of 1O2*. D2O has a rate constant for quenching of 1O2* much lower than for water. This difference in rate constants is then used to derive [1O2*] in a manner independent of other reactions that may occur. Results from these experiments allowed us to measure Rf and [1O2*] in snow from polar regions and from a mid-latitude site in the Sierra Nevada mountains of California. In addition to describing the technique and its results, we will also give a

  1. Determining the Volume of Additive Solution and Residual Plasma in Whole Blood Filtered and Buffy Coat Processed Red Cell Concentrates

    PubMed Central

    Jordan, Andrew; Acker, Jason P.

    2016-01-01

    Summary Background Residual plasma in transfused red cell concentrates (RCCs) has been associated with adverse transfusion outcomes. Despite this, there is no consensus on the standard procedure for measuring residual plasma volume. Methods The volumes of residual plasma and additive solution were measured in RCCs processed using two separation methods: whole blood filtration (WBF) and buffy coat (BC)/RCC filtration. The concentration of mannitol and albumin in RCC components was measured using colorimetric assays. Mannitol concentration was used to calculate additive solution volume. Residual plasma volume was calculated using two methods. Results Calculated RCC supernatant volumes were much lower in BC-processed components compared to WBF-processed components (BC = 97 ± 6 ml, WBF = 109 ± 4 ml; p < 0.05). Calculated additive solution volumes were greater in WBF- than in BC-processed components (BC = 81 ± 4 ml, WBF = 105 ± 2 ml; p < 0.05). Absolute residual plasma volume varied significantly based on the calculation method used. Conclusion Disparity between plasma volume calculation methods was observed. Efforts should be made to standardize residual plasma volume measurement methods in order to accurately assess the impact of residual plasma on transfusion outcomes. PMID:27330533

  2. Absolute and relative bioavailability of oral acetaminophen preparations.

    PubMed

    Ameer, B; Divoll, M; Abernethy, D R; Greenblatt, D J; Shargel, L

    1983-08-01

    Eighteen healthy volunteers received single 650-mg doses of acetaminophen by 5-min intravenous infusion, in tablet form by mouth in the fasting state, and in elixir form orally in the fasting state in a three-way crossover study. An additional eight subjects received two 325-mg tablets from two commercial vendors in a randomized crossover fashion. Concentrations of acetaminophen in multiple plasma samples collected during the 12-hr period after each dose were determined by high-performance liquid chromatography. Following a lag time averaging 3-4 min, absorption of oral acetaminophen was first order, with apparent absorption half-life values averaging 8.4 (elixir) and 11.4 (tablet) min. The mean time-to-peak concentration was significantly longer after tablet (0.75 hr) than after elixir (0.48 hr) administration. Peak plasma concentrations and elimination half-lives were similar following both preparations. Absolute systemic availability of the elixir (87%) was significantly greater than for the tablets (79%). Two commercially available tablet formulations did not differ significantly in peak plasma concentrations, time-to-peak, or total area under the plasma concentration curve and therefore were judged to be bioequivalent. PMID:6688635

  3. A novel method for measuring aromatase activity in tissue samples by determining estradiol concentrations.

    PubMed

    Tinwell, H; Rascle, J B; Colombel, S; Al Khansa, I; Freyberger, A; Bars, R

    2011-07-01

    Increasing scrutiny of endocrine disrupters has led to changes to European pesticide and biocide legislation and to the introduction of the Endocrine Disrupter Screening Program by the US EPA. One element of endocrine disrupter identification is to determine its effects on aromatase, but most available assays are limited as they depend on tritiated water production to indicate enzyme activity. Whilst acceptable for determining aromatase effects using a cell-free approach, this method is unreliable for cell or tissue-based investigations as other cytochrome P-450 isoenzyme activities can similarly produce tritiated water and consequently confound interpretation of the aromatase data. To address this lack of specificity an assay directly measuring the final estrogen product by incubating rat tissue protein with testosterone and measuring the resultant estradiol concentration was developed. Using this approach we demonstrated marked increases in enzyme activity in pregnant rat ovary samples and dose-related inhibitions when incubating non-pregnant rat ovary samples with known aromatase inhibitors. Hepatic aromatase activity was investigated using our method and by tritiated water production with microsomes from rats dosed with the antiandrogen 1,1-dichloro-2,2-bis(4 chlorophenyl)ethane. Additional cytochrome P-450s were also measured. Treatment-related increased tritiated water production and general hepatic enzyme activity were recorded but estradiol was not increased, indicating that the increased tritiated water was due to general enzyme activity and not aromatase activity. A simple and specific method has been developed that can detect aromatase inhibition and induction, which when applied to tissue samples, provides a means of generating relevant animal data concerning chemical effects on the aromatase enzyme. PMID:21259292

  4. Determination of picogram nitroglycerin plasma concentrations using capillary gas chromatography with on-column injection.

    PubMed

    Noonan, P K; Kanfer, I; Riegelman, S; Benet, L Z

    1984-07-01

    A specific, sensitive, and precise capillary gas chromatographic (GC) assay capable of analyzing picogram concentrations of nitroglycerin in human plasma was developed. The analytical procedure involves a double extraction of 1 mL of plasma with pentane, after the addition of internal standard (1 ng of 2,6-dinitrotoluene), followed by evaporation and reconstitution in 50 microL of heptane. The extract (1 microL) was injected onto a capillary column using the on-column injection technique. The GC oven temperature was programmed from 120 degrees C to 180 degrees C at a rate of 5 degrees C/min. The oven temperature was then programmed to 250 degrees C and was maintained for 10 min. The nitroglycerin and internal standard retention times were 8.6 and 11.4 min, respectively. The position of the end of the capillary column inside the detector is a critical determinant of sensitivity: the column exit must be positioned such that nitroglycerin adsorption to the detector is minimized (i.e., sensitivity maximized). The assay limit of quantitation was 25 pg/mL (CV = 7.6%) using 1 mL of plasma. This GC assay, specific for nitroglycerin in the presence of its metabolites, isosorbide dinitrate, and several other drugs, may be used to quantitate plasma levels obtained after therapeutic nitroglycerin doses. PMID:6432997

  5. Colorimetric determination of Timolol concentration based on localized surface plasmon resonance of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Amirjani, Amirmostafa; Bagheri, Mozhgan; Heydari, Mojgan; Hesaraki, Saeed

    2016-09-01

    In this work, a rapid and simple colorimetric method based on the surface plasmon resonance of silver nanoparticles (AgNPs) was developed for the detection of the drug Timolol. The method used is based on the interaction of Timolol with the surface of the as‑synthesized AgNPs, which promotes aggregation of the nanoparticles. This aggregation exploits the surface plasmon resonance through the electric dipole–dipole interaction and coupling among the agglomerated particles, hence bringing forth distinctive changes in the spectra as well as the color of colloidal silver. UV‑vis spectrophotometery was used to monitor the changes of the localized surface plasmon resonance of AgNPs at wavelengths of 400 and 550 nm. The developed colorimetric sensor has a wide dynamic range of 1.0 × 10‑7 M–1.0 × 10‑3 M for detection of Timolol with a low detection limit of 1.2 × 10‑6 M. The proposed method was successfully applied for the determination of Timolol concentration in ophthalmic eye‑drop solution with a response time lower than 40 s.

  6. Determination of boron concentration in oilfield water with a microfluidic ion exchange resin instrument.

    PubMed

    Floquet, Cedric F A; Sieben, Vincent J; MacKay, Bruce A; Mostowfi, Farshid

    2016-07-01

    We developed and validated a microfluidic instrument for interference-free determination of boron in produced water. The instrument uses a boron-specific chelating resin to separate the analyte from its complex matrix. Ten produced water samples were analyzed with the instrument and the results were successfully validated against ICP-MS measurements. Removing interference effects enables precise boron measurement for wastewater even with high total dissolved solid (TDS) levels. 1,4-Piperazinediethanesulfonic acid conditions the resin and maintains the optimum pH for boron adsorption from the sample. Boron is then eluted from the resin using a 10% sulfuric acid solution and its concentration measured with the colorimetric carminic acid assay in 95% sulfuric acid. The use of a microfluidic mixer greatly enhances the sensitivity and kinetics of the carminic acid assay, by factors of 2 and 7.5, respectively, when compared against the same assay performed manually. A maximum sensitivity of 2.5mg(-1)L, a precision of 4.2% over the 0-40.0mgL(-1) measuring range, a 0.3mgL(-1) limit of detection, and a sampling rate of up to four samples per hour were achieved. Automation and microfluidics reduce the operator workload and fluid manipulation errors, translating into safer and higher-quality measurements in the field. PMID:27154679

  7. At-sea Validation of a Birefringence Method for Determining PIC Concentrations in Seawater

    NASA Astrophysics Data System (ADS)

    Guay, C. K.; Bishop, J. K.

    2001-12-01

    We have previously described a spectrophotometer-based method for making optical measurements of particulate inorganic carbon (PIC) in seawater. This method, based on the extreme birefringence of calcium carbonate (CaCO3) relative to other major components of marine particulate matter, was developed in the laboratory using sample suspensions prepared from calcareous marine sediment material and varying amounts of non-birefringent diatomaceous earth. Here we report the first successful measurements of birefringence signals in natural seawater samples, which were obtained during a recent cruise to the North Pacific off the California coast. The spectrophotometer-based method was used onboard to measure PIC in samples collected from Niskin bottle casts in a variety of environments (nearshore to open ocean, eutrophic to oligotrophic). These samples contained a diverse mixture of particles, including calcareous, siliceous and organic material. Birefringence signals clearly above the detection level were observed in several samples, with the strongest signals occurring in productive surface waters off Point Concepcion. The spectrophotometer-based method was validated against PIC concentrations determined by chemical analysis of particulate matter collected by filtration of the Niskin bottle samples and from large-volume (1000's of L) in situ filtration performed immediately after the Niskin casts. In addition, these data were compared with in situ birefringence measurements made using a prototype profiling PIC sensor deployed on the rosette during the Niskin casts.

  8. Colorimetric determination of Timolol concentration based on localized surface plasmon resonance of silver nanoparticles.

    PubMed

    Amirjani, Amirmostafa; Bagheri, Mozhgan; Heydari, Mojgan; Hesaraki, Saeed

    2016-09-16

    In this work, a rapid and simple colorimetric method based on the surface plasmon resonance of silver nanoparticles (AgNPs) was developed for the detection of the drug Timolol. The method used is based on the interaction of Timolol with the surface of the as-synthesized AgNPs, which promotes aggregation of the nanoparticles. This aggregation exploits the surface plasmon resonance through the electric dipole-dipole interaction and coupling among the agglomerated particles, hence bringing forth distinctive changes in the spectra as well as the color of colloidal silver. UV-vis spectrophotometery was used to monitor the changes of the localized surface plasmon resonance of AgNPs at wavelengths of 400 and 550 nm. The developed colorimetric sensor has a wide dynamic range of 1.0 × 10(-7) M-1.0 × 10(-3) M for detection of Timolol with a low detection limit of 1.2 × 10(-6) M. The proposed method was successfully applied for the determination of Timolol concentration in ophthalmic eye-drop solution with a response time lower than 40 s. PMID:27504595

  9. Activated charcoal filter counting for radioiodine effluent concentration determination in protein iodinations.

    PubMed

    Button, T M; Hamilton, R G

    1982-12-01

    Regulatory agencies have recently placed emphasis upon quantification of 125I released to the environment during protein iodinations at radioiodination facilities. This necessitates air sampling in order to determine the concentration of 125I in the effluent. Air sample trapping mechanisms generally employed are activated charcoal filters. Difficulty arises in quantifying the activity of 125I trapped because of the attenuation of the 125I decay photons by the charcoal. Evaluation of the activity incident upon commercially available filters using a scintillation detector and large detector source separation is considered here. It is demonstrated that the activity in the filter may be treated as an exponential distribution within an attentuating matrix. This treatment essentially adds a constant correction factor to the counting efficiency of a given geometry for a filter-affluent flow rate combination. Finally, it is shown that an approximation assuming a uniform distribution of activity produces a large error in correction factor to the counting efficiency for the filters examined. PMID:7152949

  10. Research to Support the Determination of Spacecraft Maximum Acceptable Concentrations of Potential Atmospheric Contaminants

    NASA Technical Reports Server (NTRS)

    Orr, John L.

    1997-01-01

    In many ways, the typical approach to the handling of bibliographic material for generating review articles and similar manuscripts has changed little since the use of xerographic reproduction has become widespread. The basic approach is to collect reprints of the relevant material and place it in folders or stacks based on its dominant content. As the amount of information available increases with the passage of time, the viability of this mechanical approach to bibliographic management decreases. The personal computer revolution has changed the way we deal with many familiar tasks. For example, word processing on personal computers has supplanted the typewriter for many applications. Similarly, spreadsheets have not only replaced many routine uses of calculators but have also made possible new applications because the cost of calculation is extremely low. Objective The objective of this research was to use personal computer bibliographic software technology to support the determination of spacecraft maximum acceptable concentration (SMAC) values. Specific Aims The specific aims were to produce draft SMAC documents for hydrogen sulfide and tetrachloroethylene taking maximum advantage of the bibliographic software.

  11. Absolute Cavity Pyrgeometer to Measure the Absolute Outdoor Longwave Irradiance with Traceability to International System of Units, SI

    SciTech Connect

    Reda, I.; Zeng, J.; Scheuch, J.; Hanssen, L.; Wilthan, B.; Myers, D.; Stoffel, T.

    2012-03-01

    This article describes a method of measuring the absolute outdoor longwave irradiance using an absolute cavity pyrgeometer (ACP), U.S. Patent application no. 13/049, 275. The ACP consists of domeless thermopile pyrgeometer, gold-plated concentrator, temperature controller, and data acquisition. The dome was removed from the pyrgeometer to remove errors associated with dome transmittance and the dome correction factor. To avoid thermal convection and wind effect errors resulting from using a domeless thermopile, the gold-plated concentrator was placed above the thermopile. The concentrator is a dual compound parabolic concentrator (CPC) with 180{sup o} view angle to measure the outdoor incoming longwave irradiance from the atmosphere. The incoming irradiance is reflected from the specular gold surface of the CPC and concentrated on the 11 mm diameter of the pyrgeometer's blackened thermopile. The CPC's interior surface design and the resulting cavitation result in a throughput value that was characterized by the National Institute of Standards and Technology. The ACP was installed horizontally outdoor on an aluminum plate connected to the temperature controller to control the pyrgeometer's case temperature. The responsivity of the pyrgeometer's thermopile detector was determined by lowering the case temperature and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The responsivity is then used to calculate the absolute atmospheric longwave irradiance with an uncertainty estimate (U{sub 95}) of {+-}3.96 W m{sup 02} with traceability to the International System of Units, SI. The measured irradiance was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the Interim World Infrared Standard Group, WISG. A total of 408 readings were collected over three different nights. The calculated irradiance measured by the ACP was 1.5 W/m{sup 2} lower than that

  12. An absolute cavity pyrgeometer to measure the absolute outdoor longwave irradiance with traceability to international system of units, SI

    NASA Astrophysics Data System (ADS)

    Reda, Ibrahim; Zeng, Jinan; Scheuch, Jonathan; Hanssen, Leonard; Wilthan, Boris; Myers, Daryl; Stoffel, Tom

    2012-03-01

    This article describes a method of measuring the absolute outdoor longwave irradiance using an absolute cavity pyrgeometer (ACP), U.S. Patent application no. 13/049, 275. The ACP consists of domeless thermopile pyrgeometer, gold-plated concentrator, temperature controller, and data acquisition. The dome was removed from the pyrgeometer to remove errors associated with dome transmittance and the dome correction factor. To avoid thermal convection and wind effect errors resulting from using a domeless thermopile, the gold-plated concentrator was placed above the thermopile. The concentrator is a dual compound parabolic concentrator (CPC) with 180° view angle to measure the outdoor incoming longwave irradiance from the atmosphere. The incoming irradiance is reflected from the specular gold surface of the CPC and concentrated on the 11 mm diameter of the pyrgeometer's blackened thermopile. The CPC's interior surface design and the resulting cavitation result in a throughput value that was characterized by the National Institute of Standards and Technology. The ACP was installed horizontally outdoor on an aluminum plate connected to the temperature controller to control the pyrgeometer's case temperature. The responsivity of the pyrgeometer's thermopile detector was determined by lowering the case temperature and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The responsivity is then used to calculate the absolute atmospheric longwave irradiance with an uncertainty estimate (U95) of ±3.96 W m-2 with traceability to the International System of Units, SI. The measured irradiance was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the Interim World Infrared Standard Group, WISG. A total of 408 readings were collected over three different nights. The calculated irradiance measured by the ACP was 1.5 W/m2 lower than that measured by the two

  13. Absolute and relative dosimetry for ELIMED

    SciTech Connect

    Cirrone, G. A. P.; Schillaci, F.; Scuderi, V.; Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F.; Carpinelli, M.; Presti, D. Lo; Raffaele, L.; Tramontana, A.; Cirio, R.; Sacchi, R.; Monaco, V.; Marchetto, F.; Giordanengo, S.

    2013-07-26

    The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

  14. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

    A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).

  15. Absolute calibration of TFTR helium proportional counters

    SciTech Connect

    Strachan, J.D.; Diesso, M.; Jassby, D.; Johnson, L.; McCauley, S.; Munsat, T.; Roquemore, A.L.; Barnes, C.W. |; Loughlin, M. |

    1995-06-01

    The TFTR helium proportional counters are located in the central five (5) channels of the TFTR multichannel neutron collimator. These detectors were absolutely calibrated using a 14 MeV neutron generator positioned at the horizontal midplane of the TFTR vacuum vessel. The neutron generator position was scanned in centimeter steps to determine the collimator aperture width to 14 MeV neutrons and the absolute sensitivity of each channel. Neutron profiles were measured for TFTR plasmas with time resolution between 5 msec and 50 msec depending upon count rates. The He detectors were used to measure the burnup of 1 MeV tritons in deuterium plasmas, the transport of tritium in trace tritium experiments, and the residual tritium levels in plasmas following 50:50 DT experiments.

  16. Learning in the temporal bisection task: Relative or absolute?

    PubMed

    de Carvalho, Marilia Pinheiro; Machado, Armando; Tonneau, François

    2016-01-01

    We examined whether temporal learning in a bisection task is absolute or relational. Eight pigeons learned to choose a red key after a t-seconds sample and a green key after a 3t-seconds sample. To determine whether they had learned a relative mapping (short→Red, long→Green) or an absolute mapping (t-seconds→Red, 3t-seconds→Green), the pigeons then learned a series of new discriminations in which either the relative or the absolute mapping was maintained. Results showed that the generalization gradient obtained at the end of a discrimination predicted the pattern of choices made during the first session of a new discrimination. Moreover, most acquisition curves and generalization gradients were consistent with the predictions of the learning-to-time model, a Spencean model that instantiates absolute learning with temporal generalization. In the bisection task, the basis of temporal discrimination seems to be absolute, not relational. PMID:26752233

  17. Use of dissolved H2 concentrations to determine distribution of microbially catalyzed redox reactions in anoxic groundwater

    USGS Publications Warehouse

    Lovley, D.R.; Chapelle, F.H.; Woodward, J.C.

    1994-01-01

    The potential for using concentrations of dissolved H2 to determine the distribution of redox processes in anoxic groundwaters was evaluated. In pristine aquifers in which standard geochemical measurements indicated that Fe-(III) reduction, sulfate reduction, or methanogenesis was the terminal electron accepting process (TEAP), the H2 concentrations were similar to the H2 concentrations that have previously been reported for aquatic sediments with the same TEAPs. In two aquifers contaminated with petroleum products, it was impossible with standard geochemical analyses to determine which TEAPs predominated in specific locations. However, the TEAPs predicted from measurements of dissolved H2 were the same as those determined directly through measurements of microbial processes in incubated aquifer material. These results suggest that H2 concentrations may be a useful tool for analyzing the redox chemistry of nonequilibrium groundwaters.

  18. Absolute photoionization cross-section of the methyl radical.

    SciTech Connect

    Taatjes, C. A.; Osborn, D. L.; Selby, T.; Meloni, G.; Fan, H.; Pratt, S. T.; Chemical Sciences and Engineering Division; SNL

    2008-01-01

    The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH{sub 3} photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; {sigma}{sub CH}(10.2 eV) = (5.7 {+-} 0.9) x 10{sup -18} cm{sup 2} and {sigma}{sub CH{sub 3}}(11.0 eV) = (6.0 {+-} 2.0) x 10{sup -18} cm{sup 2}. The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH{sub 3} and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.460 eV, (5.5 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.466 eV, and (4.9 {+-} 2.0) x 10{sup -18} cm{sup 2} at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.

  19. Determination of radionuclide concentrations in ground level air using the ASS-500 high volume sampler

    SciTech Connect

    Frenzel, E.; Arnold, D.; Wershofen, H.

    1996-06-01

    A method for determination of radionuclide concentrations in air aerosol samples collected by the high volume aerosol sampler ASS-500 was elaborated. The aerosol sampling station ASS-500 is a Stand alone, all-weather proofed instrument. It is designed for representative sampling of airborne radionuclides from ground level air at a height of about 1.5 m above ground level. The ASS-500 station enables continuous air monitoring both normal and emergency Situations. The collection of aerosols on the Petrianov FPP-15-1.5 type filter out of an air volume of about 100,000 m{sup 3} (sampling period 1 wk) or of about 250,000 m{sup 3} (sampling period 3 wk) admits accurate spectrometric low level measurements of natural and artificial radionuclides. The achieved detection limit is 0.5 {mu}Bq m{sup -3} and 0.2 {mu}Bq m{sup -3} for {sup 137}Cs, respectively. A new developed air flow Meter system allows to enhance the collected air volume to about 150,000 m{sup 3} per week and lowers the detection limit to <0.4 {mu}Bq m{sup -3} for {sup 137}Cs for weekly collected aerosol samples. In Poland the CLOR uses 9 Stations ASS-500 at different sites as atmospheric radioactivity control system. On the basis of spectrometric measurements of natural and artificial radionuclides in the collected aerosol samples at the different sites, CLOR establishes a weekly report about the radiological situation at Poland for responsible authorities. The very low achievable detection limit of the Station ASS-500 due 10 the high air flow fate and the long possible sampling period were the key argument for other government radiation protection authorities in Europe to introduce the Station ASS-500 into their low level radionuclide atmospheric monitoring programs (Austria, Belarus, France, Germany, Iceland, Spain, Switzerland, Ukraine).

  20. Selenium Preconcentration in Geological Materials for Determination at sub-μ g\\ g-1 Concentration

    NASA Astrophysics Data System (ADS)

    Bedard, L. P.

    2004-05-01

    Selenium is important because it is a path finder element in economic geology. It has similar geochemical properties as sulfur, but slightly less mobile and less volatile in sulfides. Although its environmental cycle is better understood, its geological cycle is almost unknown. In geological samples, Se concentration ranges 0,02-1 μ g\\ g-1. Se has many spectral interefences in ICP-MS, rendering difficult to determine. INAA detection limit for geological samples is about 10 μ g\\ g-1. The analytical difficulties are one of the main reason why the geological cycle of Se is so poorly known. The preconcentration of Se with Thiol Cotton Fiber (TCF) followed by atomic absorption (AA) has been modified to be used with INAA. The modified technique involves sample dissolution (HF-HNO3) and evaporation to dryness at low temperature (55-60 oC) to keep Se in solution. Se is converted to SeIV by adding 5-6 mol l-1 HCl and heating covered in a boiling bath (95-100oC). Sample is diluted with deionized water to obtain 0,3 - 1 mol l-1 HCl and then collected on TCF. TCF is put in a polyethylene vial for irradiation in the SLOWPOKE II reactor for 10 seconds at a neutron flux of 1015 m-2 s-1. The 162 KeV peak of 77Se (half-life 17,36 sec) is read for 20 seconds after a decay of 7 seconds. Results for certified reference materials show the TCF preconcentration technique followed by INAA provides results comparable with AA with a detection limit of approximately 0,05 μ g\\ g-1. Moreover INAA provides many advantages such as eliminating the desorption step and is less time consuming than AA.

  1. Technical note: An improved approach to determining background aerosol concentrations with PILS sampling on aircraft

    NASA Astrophysics Data System (ADS)

    Fukami, Christine S.; Sullivan, Amy P.; Ryan Fulgham, S.; Murschell, Trey; Borch, Thomas; Smith, James N.; Farmer, Delphine K.

    2016-07-01

    Particle-into-Liquid Samplers (PILS) have become a standard aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatography (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line analysis procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chemical background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chemical components analyzed from 137 background samples (taken from ∼78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estimation of background samples - and thus an underestimation of sample concentrations. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO3-), nitrite (NO2-), ammonium (NH4+), sulfate (SO42-), potassium (K+) and calcium (Ca2+), respectively. The difference in backgrounds calculated from assuming a Gaussian distribution versus a log-normal distribution were most extreme for NH4+, resulting in a background that was 1.58× that determined from fitting a log-normal distribution.

  2. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... subject to subpart G of 40 CFR part 63, the owner or operator may measure HAP or TOC concentration with... 40 CFR part 63, subpart G sources. Process vents subject to only 40 CFR part 60, subparts RRR or NNN... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Concentration for Group...

  3. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... subject to subpart G of 40 CFR part 63, the owner or operator may measure HAP or TOC concentration with... 40 CFR part 63, subpart G sources. Process vents subject to only 40 CFR part 60, subparts RRR or NNN... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Concentration for Group...

  4. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... subject to subpart G of 40 CFR part 63, the owner or operator may measure HAP or TOC concentration with... 40 CFR part 63, subpart G sources. Process vents subject to only 40 CFR part 60, subparts RRR or NNN... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Concentration for Group...

  5. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... subject to subpart G of 40 CFR part 63, the owner or operator may measure HAP or TOC concentration with... 40 CFR part 63, subpart G sources. Process vents subject to only 40 CFR part 60, subparts RRR or NNN... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Concentration for Group...

  6. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... subject to subpart G of 40 CFR part 63, the owner or operator may measure HAP or TOC concentration with... 40 CFR part 63, subpart G sources. Process vents subject to only 40 CFR part 60, subparts RRR or NNN... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Concentration for Group...

  7. Are dietary choline and betaine intakes determinants of total homocysteine concentration?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elevated homocysteine concentrations are associated with an increased risk of cardiovascular disease and a decline in cognitive function. Intakes of choline and betaine, as methyl donors, may affect homocysteine concentrations. The objective was to examine whether choline and betaine intakes, assess...

  8. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  9. Concentration dependence of nanochannel impedance and the determination of surface charge.

    PubMed

    Schiffbauer, Jarrod; Liel, Uri; Yossifon, Gilad

    2014-03-01

    In this paper, we demonstrate the variation of nanochannel impedance with bulk (reservoir) electrolyte concentration. The impedance of a nanochannel is shown to correspond to a characteristic deformed semicircular arc. The degree of deformation decreases with increasing concentration, and at a sufficiently low concentration the complex impedance saturates, becoming essentially independent of the reservoir concentration. This behavior is indicative of a surface-conduction dominant regime. Here we demonstrate that this effect extends beyond dc conductance and affects the ac response of the system as well, including both phase relationship and magnitude. The nanochannel resistance, obtained from low-voltage ac measurements, is then used to extract the nanochannel surface charge density. This is found to increase in magnitude with increasing electrolyte concentration. PMID:24730947

  10. Concentration dependence of nanochannel impedance and the determination of surface charge

    NASA Astrophysics Data System (ADS)

    Schiffbauer, Jarrod; Liel, Uri; Yossifon, Gilad

    2014-03-01

    In this paper, we demonstrate the variation of nanochannel impedance with bulk (reservoir) electrolyte concentration. The impedance of a nanochannel is shown to correspond to a characteristic deformed semicircular arc. The degree of deformation decreases with increasing concentration, and at a sufficiently low concentration the complex impedance saturates, becoming essentially independent of the reservoir concentration. This behavior is indicative of a surface-conduction dominant regime. Here we demonstrate that this effect extends beyond dc conductance and affects the ac response of the system as well, including both phase relationship and magnitude. The nanochannel resistance, obtained from low-voltage ac measurements, is then used to extract the nanochannel surface charge density. This is found to increase in magnitude with increasing electrolyte concentration.

  11. Full Vector Analyses of Cryptochron C2r.2r-l (ca. 2.42-2.44 Ma) Recorded on Koolau Volcano at Halawa, Oahu, Hawaii: Evidence From Directions, Absolute Paleointensity Determinations and 40Ar/39Ar Studies.

    NASA Astrophysics Data System (ADS)

    Browne, E. J.; Herrero-Bervera, E.; Singer, B.

    2005-12-01

    New paleomagnetic measurements (directions and paleointensity determinations), coupled with precise 40Ar/39Ar radioisotopic dating, are revolutionizing our understanding of the geodynamo by providing detailed terrestrial lava records of the short-term behavior of the paleomagnetic field. As part of an investigation of the evolution of Koolau Volcano (one of the volcanoes comprising Oahu Island) and the short-term behavior of the geomagnetic field, we have sampled a long volcanic section located on the buttressed flank of the volcano within Halawa Valley. Prior paleomagnetic and K-Ar investigations of the Koolau (Volcano) Series revealed excursional directions (Site F of Doell and Dalrymple, 1973). The alkaline composition of lava flows, easy access, and close geographical proximity to K-Ar dated lava flows made this newly studied 120 m thick sequence of flows in Halawa valley an excellent candidate for detailed paleomagnetic analysis. At least eight samples collected from each of 28 successive flow-sites were stepwise demagnetized by both alternating field (5mT to 100mT) and thermal (from 28o C to 575-650oC) methods, and the mean directions obtained by principal component analysis. All samples yielded a strong and stable ChRM trending towards the origin based on no less than seven to nine steps, with thermal and AF results agreeing to a very high degree. Low field susceptibility versus temperature (k-T) analyses were conducted for individual lava flows, and the majority of them show reversible curves. Curie point determinations revealed a temperature close to or equal to 580oC, indicative of almost pure magnetite for most of the flows. Magnetic grain sizes analysis indicated SD-PSD sizes. The mean directions of magnetization of the entire section sampled indicate that about 10 m of the section are characterized by excursional directions (5 lava flows). In addition to the directional analyses we performed absolute paleointensity determinations on the 28 lavas

  12. Determination of Uranium Metal Concentration in Irradiated Fuel Storage Basin Sludge Using Selective Dissolution

    SciTech Connect

    Delegard, Calvin H.; Sinkov, Sergey I.; Chenault, Jeffrey W.; Schmidt, Andrew J.; Welsh, Terri L.; Pool, Karl N.

    2014-03-01

    Uranium metal corroding in water-saturated sludges now held in the US Department of Energy Hanford Site K West irradiated fuel storage basin can create hazardous hydrogen atmospheres during handling, immobilization, or subsequent transport and storage. Knowledge of uranium metal concentration in sludge thus is essential to safe sludge management and process design, requiring an expeditious routine analytical method to detect uranium metal concentrations as low as 0.03 wt% in sludge even in the presence of 30 wt% or higher total uranium concentrations.

  13. Determination of optimum sunlight concentration level in space for 3-4 cascade solar cells

    NASA Technical Reports Server (NTRS)

    Curtis, H. B.

    1982-01-01

    The optimum range of concentration in space for III-V cascade cells has been calculated using a realistic solar cell diode equation. Temperature was varied with concentration using several models and ranged from 55 deg at one sun to between 80 deg and 200 deg C at 100 suns. A variety of series resistance and internal resistances were used. Coefficients of the diffusion and recombination terms are strongly temperature dependent. The study indicates that the maximum efficiency of 30 percent occurs in the 50 to 100 X sun concentration range provided series resistance is below 0.015 ohm sq cm and cell temperature is about 80 C at 100 suns.

  14. Determination of optimum sunlight concentration level in space for 3-5 cascade solar cells

    NASA Technical Reports Server (NTRS)

    Curtis, H. B.

    1982-01-01

    The optimum range of concentration levels in space for III-V cascade cells was calculated using a realistic solar cell diode equation. Temperature was varied with concentration using several models and ranged from 55 C at 1 sun to between 80 and 200 C at 100 suns. A variety of series resistance and internal resistances were used. Coefficients of the diffusion and recombination terms are strongly temperature dependent. The study indicates that the maximum efficiency of 30 percent occurs in the 50 to 100 sun concentration range provided series resistance is below 0.015 ohm-sq cm and cell temperature is about 80 C at 100 suns.

  15. Blood pressure targets and absolute cardiovascular risk.

    PubMed

    Odutayo, Ayodele; Rahimi, Kazem; Hsiao, Allan J; Emdin, Connor A

    2015-08-01

    In the Eighth Joint National Committee guideline on hypertension, the threshold for the initiation of blood pressure-lowering treatment for elderly adults (≥60 years) without chronic kidney disease or diabetes mellitus was raised from 140/90 mm Hg to 150/90 mm Hg. However, the committee was not unanimous in this decision, particularly because a large proportion of adults ≥60 years may be at high cardiovascular risk. On the basis of Eighth Joint National Committee guideline, we sought to determine the absolute 10-year risk of cardiovascular disease among these adults through analyzing the National Health and Nutrition Examination Survey (2005-2012). The primary outcome measure was the proportion of adults who were at ≥20% predicted absolute cardiovascular risk and above goals for the Seventh Joint National Committee guideline but reclassified as at target under the Eighth Joint National Committee guideline (reclassified). The Framingham General Cardiovascular Disease Risk Score was used. From 2005 to 2012, the surveys included 12 963 adults aged 30 to 74 years with blood pressure measurements, of which 914 were reclassified based on the guideline. Among individuals reclassified as not in need of additional treatment, the proportion of adults 60 to 74 years without chronic kidney disease or diabetes mellitus at ≥20% absolute risk was 44.8%. This corresponds to 0.8 million adults. The proportion at high cardiovascular risk remained sizable among adults who were not receiving blood pressure-lowering treatment. Taken together, a sizable proportion of reclassified adults 60 to 74 years without chronic kidney disease or diabetes mellitus was at ≥20% absolute cardiovascular risk. PMID:26056340

  16. Determining the 95% limit of detection for waterborne pathogen analyses from primary concentration to qPCR.

    PubMed

    Stokdyk, Joel P; Firnstahl, Aaron D; Spencer, Susan K; Burch, Tucker R; Borchardt, Mark A

    2016-06-01

    The limit of detection (LOD) for qPCR-based analyses is not consistently defined or determined in studies on waterborne pathogens. Moreover, the LODs reported often reflect the qPCR assay alone rather than the entire sample process. Our objective was to develop an approach to determine the 95% LOD (lowest concentration at which 95% of positive samples are detected) for the entire process of waterborne pathogen detection. We began by spiking the lowest concentration that was consistently positive at the qPCR step (based on its standard curve) into each procedural step working backwards (i.e., extraction, secondary concentration, primary concentration), which established a concentration that was detectable following losses of the pathogen from processing. Using the fraction of positive replicates (n = 10) at this concentration, we selected and analyzed a second, and then third, concentration. If the fraction of positive replicates equaled 1 or 0 for two concentrations, we selected another. We calculated the LOD using probit analysis. To demonstrate our approach we determined the 95% LOD for Salmonella enterica serovar Typhimurium, adenovirus 41, and vaccine-derived poliovirus Sabin 3, which were 11, 12, and 6 genomic copies (gc) per reaction (rxn), respectively (equivalent to 1.3, 1.5, and 4.0 gc L(-1) assuming the 1500 L tap-water sample volume prescribed in EPA Method 1615). This approach limited the number of analyses required and was amenable to testing multiple genetic targets simultaneously (i.e., spiking a single sample with multiple microorganisms). An LOD determined this way can facilitate study design, guide the number of required technical replicates, aid method evaluation, and inform data interpretation. PMID:27023926

  17. Determining the 95% limit of detection for waterborne pathogen analyses from primary concentration to qPCR

    USGS Publications Warehouse

    Stokdyk, Joel P.; Firnstahl, Aaron; Spencer, Susan K.; Burch, Tucker R; Borchardt, Mark A.

    2016-01-01

    The limit of detection (LOD) for qPCR-based analyses is not consistently defined or determined in studies on waterborne pathogens. Moreover, the LODs reported often reflect the qPCR assay alone rather than the entire sample process. Our objective was to develop an approach to determine the 95% LOD (lowest concentration at which 95% of positive samples are detected) for the entire process of waterborne pathogen detection. We began by spiking the lowest concentration that was consistently positive at the qPCR step (based on its standard curve) into each procedural step working backwards (i.e., extraction, secondary concentration, primary concentration), which established a concentration that was detectable following losses of the pathogen from processing. Using the fraction of positive replicates (n = 10) at this concentration, we selected and analyzed a second, and then third, concentration. If the fraction of positive replicates equaled 1 or 0 for two concentrations, we selected another. We calculated the LOD using probit analysis. To demonstrate our approach we determined the 95% LOD for Salmonella enterica serovar Typhimurium, adenovirus 41, and vaccine-derived poliovirus Sabin 3, which were 11, 12, and 6 genomic copies (gc) per reaction (rxn), respectively (equivalent to 1.3, 1.5, and 4.0 gc L−1 assuming the 1500 L tap-water sample volume prescribed in EPA Method 1615). This approach limited the number of analyses required and was amenable to testing multiple genetic targets simultaneously (i.e., spiking a single sample with multiple microorganisms). An LOD determined this way can facilitate study design, guide the number of required technical replicates, aid method evaluation, and inform data interpretation.

  18. Determination of cholesterol concentration in human milk samples using attenuated total reflectance Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamelska, A. M.; Pietrzak-Fiećko, R.; Bryl, K.

    2013-03-01

    Results of an inexpensive and rapid evaluation of the cholesterol concentration in human milk using ATR-FTIR techniques are presented. The FTIR spectrum of pure cholesterol was characterized and quantitatively estimated in the region between 2800 and 3200 cm-1. 125 samples at different stages of lactation were analyzed. There were no differences between the cholesterol concentrations in the samples of early (1-3 months), medium (4-6 months), and late (> 6 months) lactation stages ( p = 0.096968). The cholesterol concentration ranged from 4.30 to 21.77 mg/100 cm3. Such a broad range was due to the differences between the samples from different women ( p = 0.000184). The results indicate that ATR-FTIR has potential for rapid estimation of cholesterol concentration in human milk.

  19. A BIOPSY PROCEDURE FOR DETERMINING FILET AND PREDICTING WHOLE-FISH MERCURY CONCENTRATION

    EPA Science Inventory

    Although mercury contamination of fish is a widespread phenomenon, its regional evaluation is hindered by the reluctance of permitting agencies to grant collection permits, securing adequate freezer space, and processing whole, large fish or filets. We evaluated Hg concentration...

  20. Are dietary choline and betaine intakes determinants of total homocysteine concentration?1234

    PubMed Central

    Lee, Jung Eun; Jacques, Paul F; Dougherty, Lauren; Selhub, Jacob; Giovannucci, Edward; Zeisel, Steven H

    2010-01-01

    Background: Elevated homocysteine concentrations are associated with an increased risk of cardiovascular disease and a decline in cognitive function. Intakes of choline and betaine, as methyl donors, may affect homocysteine concentrations. Objective: The objective was to examine whether choline and betaine intakes, assessed from food-frequency questionnaires, are associated with total plasma homocysteine concentrations under both fasting and post–methionine-load conditions in both pre– and post–folic acid fortification periods in the United States. Design: We assessed the association between choline and betaine intakes and fasting and post–methionine-load homocysteine concentrations using the US Department of Agriculture revised food-composition tables and evaluated whether the associations varied by folic acid fortification periods in 1325 male and 1407 female participants in the sixth examination (1995–1998) of the Framingham Offspring Study. Results: A higher choline-plus-betaine intake was associated with lower concentrations of post–methionine-load homocysteine; the multivariate geometric means were 24.1 μmol/L (95% CI: 23.4, 24.9 μmol/L) in the top quintile of intake and 25.0 μmol/L (95% CI: 24.2, 25.7 μmol/L) in the bottom quintile (P for trend = 0.01). We found an inverse association between choline-plus-betaine intake and fasting homocysteine concentrations; the multivariate geometric mean fasting homocysteine concentrations were 9.6 μmol/L (95% CI: 9.3, 9.9 μmol/L) in the top quintile and 10.1 μmol/L (95% CI: 9.8, 10.4 μmol/L) in the bottom quintile (P for trend < 0.001). When we stratified by plasma folate and vitamin B-12 concentrations, the inverse association was limited to participants with low plasma folate or vitamin B-12 concentrations. In the postfortification period, the inverse association between choline-plus-betaine intake and either fasting or post–methionine-load homocysteine was no longer present. Conclusions: Choline

  1. Host-parasite relationships as determinants of heavy metal concentrations in perch (Perca fluviatilis) and its intestinal parasite infection.

    PubMed

    Brázová, Tímea; Hanzelová, Vladimíra; Miklisová, Dana; Šalamún, Peter; Vidal-Martínez, Víctor M

    2015-12-01

    The concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn and their bioconcentration factors (BCFs) were determined in two intestinal parasites, an acanthocephalan, Acanthocephalus lucii, a tapeworm, Proteocephalus percae, present in the same host, the European perch (Perca fluviatilis, L.), in the heavily polluted Ružín reservoir in eastern Slovakia. The bioaccumulation of heavy metals in the fish organs and parasites was studied for acanthocephalan and tapeworm monoinfections or mixed infections by the two parasites and for the size of their parasitic infrapopulations. Bioconcentration factors (c[parasite]/c[muscle tissue]) showed that the concentrations of As, Ni, Pb and Zn were higher in mixed infections than in monoinfections. Negative correlations between heavy metal concentrations in perch organs and the parasites were found. For example, higher concentrations of Ni and Zn in both parasite species corresponded with lower metal concentrations in perch and hard roe. Likewise, significant negative relationships between metal concentrations in fish organs and number of parasites were noticed with lower levels of Pb in fish harbouring higher numbers of tapeworms. Similarly, in both parasite species the concentrations of some essential elements (Cr, Mn) were lower at high infection intensities compared to low intensities. Our study revealed that the differential concentration of heavy metals in perch organs was affected by the type of infection (mono- or mixed-infection), and needs to be considered in field ecotoxicological and parasitological studies as a potentially important factor influencing the pollutant concentrations in fish. PMID:26432028

  2. Concentrations of drugs determined in blood samples collected from suspected drugged drivers in England and Wales.

    PubMed

    Burch, Hilary J; Clarke, Elizabeth J; Hubbard, Alison M; Scott-Ham, Michael

    2013-05-01

    This communication reports the blood concentrations of alcohol and drugs from 376 cases of alleged driving under the influence of drugs analysed at the Forensic Science Service Chorley and London laboratories between February 2010 and March 2011. The samples were analysed for alcohol, amphetamine, benzodiazepines, cocaine, MDMA, opiates, γ-hydroxybutyrate (GHB), ketamine, methadone and methylmethcathinone (the 4-isomer of which is known as mephedrone). The results were interpreted with respect to the number and type of drugs of abuse detected and the concentrations measured. Alcohol was quantified in 113 cases (30%), and of these a level in excess of the prescribed UK limit for driving of 80 mg% was present in 90 cases. In 80 cases, only the concentration of alcohol was measured, the concentrations of both drugs and alcohol were measured in 33 cases. In the remaining 263 cases, only the concentrations of relevant drugs of abuse were measured. The most common drug of abuse quantified was cocaine which was detected in 92 cases, either as the active drug or as its major metabolite benzoylecgonine, followed by diazepam which was quantified in 76 cases. Concentrations of some new drugs, and drugs rarely reported in driving under the influence cases are also presented. PMID:23622475

  3. Determination of glucose concentration based on pulsed laser induced photoacoustic technique and least square fitting algorithm

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2015-08-01

    In this paper, a noninvasive glucose concentration monitoring setup based on the photoacoustic technique was established. In this setup, a 532nm pumped Q switched Nd: YAG tunable pulsed laser with repetition rate of 20Hz was used as the photoacoustic excitation light source, and a ultrasonic transducer with central response frequency of 9.55MHz was used as the detector of the photoacoustic signal of glucose. As the preliminary exploration of the blood glucose concentration, a series of in vitro photoacoustic monitoring of glucose aqueous solutions by using the established photoacoustic setup were performed. The photoacoustic peak-to-peak values of different concentrations of glucose aqueous solutions induced by the pulsed laser with output wavelength of 1300nm to 2300nm in interval of 10nm were obtained with the average times of 512. The differential spectral and the first order derivative spectral method were used to get the characteristic wavelengths. For the characteristic wavelengths of glucose, the least square fitting algorithm was used to establish the relationship between the glucose concentrations and photoacoustic peak-to-peak values. The characteristic wavelengths and the predicted concentrations of glucose solution were obtained. Experimental results demonstrated that the prediction effect of characteristic wavelengths of 1410nm and 1510nm were better than others, and this photoacoustic setup and analysis method had a certain potential value in the monitoring of the blood glucose concentration.

  4. Influence of Analyte Concentration on Stability Constant Values Determined by Capillary Electrophoresis.

    PubMed

    Sursyakova, Viktoria V; Burmakina, Galina V; Rubaylo, Anatoly I

    2016-08-01

    The influence of analyte concentration when compared with the concentration of a charged ligand in background electrolyte (BGE) on the measured values of electrophoretic mobilities and stability constants (association, binding or formation constants) is studied using capillary electrophoresis (CE) and a dynamic mathematical simulator of CE. The study is performed using labile complexes (with fast kinetics) of iron (III) and 5-sulfosalicylate ions (ISC) as an example. It is shown that because the ligand concentration in the analyte zone is not equal to that in BGE, considerable changes in the migration times and electrophoretic mobilities are observed, resulting in systematic errors in the stability constant values. Of crucial significance is the slope of the dependence of the electrophoretic mobility decrease on the ligand equilibrium concentration. Without prior information on this dependence to accurately evaluate the stability constants for similar systems, the total ligand concentration must be at least >50-100 times higher than the total concentration of analyte. Experimental ISC peak fronting and the difference between the direction of the experimental pH dependence of the electrophoretic mobility decrease and the mathematical simulation allow assuming the presence of capillary wall interaction. PMID:27090731

  5. Determination of tolerable fatty acids and cholera toxin concentrations using human intestinal epithelial cells and BALB/c mouse macrophages.

    PubMed

    Tamari, Farshad; Tychowski, Joanna; Lorentzen, Laura

    2013-01-01

    The positive role of fatty acids in the prevention and alleviation of non-human and human diseases have been and continue to be extensively documented. These roles include influences on infectious and non-infectious diseases including prevention of inflammation as well as mucosal immunity to infectious diseases. Cholera is an acute intestinal illness caused by the bacterium Vibrio cholerae. It occurs in developing nations and if left untreated, can result in death. While vaccines for cholera exist, they are not always effective and other preventative methods are needed. We set out to determine tolerable concentrations of three fatty acids (oleic, linoleic and linolenic acids) and cholera toxin using mouse BALB/C macrophages and human intestinal epithelial cells, respectively. We solubilized the above fatty acids and used cell proliferation assays to determine the concentration ranges and specific concentrations of the fatty acids that are not detrimental to human intestinal epithelial cell viability. We solubilized cholera toxin and used it in an assay to determine the concentration ranges and specific concentrations of cholera toxin that do not statistically decrease cell viability in BALB/C macrophages. We found the optimum fatty acid concentrations to be between 1-5 ng/μl, and that for cholera toxin to be < 30 ng per treatment. This data may aid future studies that aim to find a protective mucosal role for fatty acids in prevention or alleviation of cholera infections. PMID:23748896

  6. Determination of perchlorate in drinking water by ion chromatography using macrocycle-based concentration and separation methods.

    PubMed

    Lamb, John D; Simpson, David; Jensen, Bryce D; Gardner, Joseph S; Peterson, Quinn P

    2006-06-16

    Macrocycle-based ion chromatography provides a convenient, reliable method for the determination of perchlorate ion, which is currently of great interest to the environmental community. This study shows that effective perchlorate determinations can be made using standard conductimetric detection by combining an 18-crown-6-based mobile phase with an underivatized reversed-phase mobile phase ion chromatography (MPIC) column. One unique feature of this method is the flexibility in column capacity that is achieved through simple variations in eluent concentrations of 18-crown-6 and KOH, facilitating the separation of target analyte anions such as perchlorate. Using a standard anion exchange column as concentrator makes possible the determination of perchlorate as low as 0.2 ug/L in low ionic strength matrices. Determination of perchlorate at the sub-ug/L level in pure water and in spiked local city hard water samples with high background ion concentrations can be achieved this way. However, like other IC techniques, this method is challenged to achieve analyses at the ug/L level in the demanding high ionic strength matrix described by the United States Environmental Protection Agency (EPA) (1,000 mg/L chloride, sulfate and carbonate). We approached this challenge by use of the Cryptand C1 concentrator column, provided by Dionex Corporation, to effectively preconcentrate perchlorate while reducing background ion concentrations in the high ionic strength matrix. The retention characteristics of the concentrator column were studied in order to maximize its effectiveness for perchlorate determinations. The method makes possible the determination of perchlorate at the 5 ug/L level in the highest ionic strength matrix described by the EPA. PMID:16516902

  7. Intracellular inducer Hg2+ concentration is rate determining for the expression of the mercury-resistance operon in cells.

    PubMed

    Yu, H; Chu, L; Misra, T K

    1996-05-01

    Experiments involving mercury resistance mer operon-lacZ fusions, point mutations in the mercuric ion reductase merA gene, and transcomplementation have revealed that in Hg2+-resistant cells, the inducer Hg2+ concentration is rate determining for activation of transcription. mer operon expression is activated by the presence of nanomolar concentrations of Hg2+ in liquid media only when the mercuric ion reductase function is artificially inactivated in cells, whereas cells with active mercuric ion reductase require micromolar concentrations of Hg2+ for effective induction of the operon. PMID:8626343

  8. Determinants of serum concentrations of organochlorine compounds in Swedish pregnant women: a cross-sectional study

    PubMed Central

    Glynn, Anders; Aune, Marie; Darnerud, Per Ola; Cnattingius, Sven; Bjerselius, Rickard; Becker, Wulf; Lignell, Sanna

    2007-01-01

    Background We performed a cross-sectional study of associations between personal characteristics and lipid-adjusted serum concentrations of certain PCB congeners and chlorinated pesticides/metabolites among 323 pregnant primiparous women from Uppsala County (age 18–41 years) sampled 1996–1999. Methods Extensive personal interviews and questionnaires about personal characteristics were performed both during and after pregnancy. Concentrations of organochlorine compounds in serum lipids in late pregnancy were analysed by gas chromatography. Associations between personal characteristics and serum levels of organochlorine compounds were analysed by multiple linear regression. Results Participation rate was 82% (325 of 395 women). Serum concentrations of PCB congeners IUPAC no. 28, 52, 101, 105 and 167, and o, p'-DDT and -DDE, p, p'-DDT and -DDD, oxychlordane, and γ- and α-HCH were in many cases below the limit of quantification (LOQ). No statistical analysis of associations with personal characteristics could be performed for these substances. Concentrations of PCB congeners IUPAC no. 118, 138, 153, 156 and 180, HCB, β-HCH, trans-nonachlor and p, p'-DDE increased with increased age and were highest in women sampled early during the 4 year study period. This shows that older women and women sampled early in the study had experienced the highest life-time exposure levels, probably mainly during childhood and adolescence. The importance of early exposures was supported by lower PCB concentrations and higher β-HCH and p, p'-DDE concentrations among women born in non-Nordic countries. Moreover, serum concentrations of certain PCBs and pesticide/metabolites were positively associated with consumption of fatty fish during adolescence, and concentrations of CB 156, CB 180 and p, p'-DDE increased significantly with number of months women had been breast-fed during infancy. Short-term changes in bodily constitution may, however, also influence serum concentrations, as

  9. Intake of whole grains and vegetables determines the plasma enterolactone concentration of Danish women.

    PubMed

    Johnsen, Nina F; Hausner, Helene; Olsen, Anja; Tetens, Inge; Christensen, Jane; Knudsen, Knud Erik Bach; Overvad, Kim; Tjønneland, Anne

    2004-10-01

    The mammalian lignan enterolactone (ENL), which is produced from dietary plant-lignan precursors by the intestinal microflora, may protect against breast cancer and other hormone-dependent cancers. This cross-sectional study examined which variables related to diet and lifestyle were associated with high plasma concentrations of ENL in Danish postmenopausal women. Plasma ENL was measured by time-resolved fluoroimmunoassay in 857 Danish women aged 50-64 y who participated in a prospective cohort study. Diet was assessed using a semiquantitative FFQ, and background information on lifestyle was collected using a self-administered questionnaire. Multiple analyses of covariance were completed in two steps. The median plasma ENL concentration was 27 nmol/L (range 0-455 nmol/L). In covariance analyses, positive associations were found between consumption of cereals, vegetables, and beverages and plasma ENL concentration. When analyzing subgroups of these food groups, the associations were confined to whole-grain products, cabbage, leafy vegetables, and coffee. For fat and the nondietary variables, negative associations between BMI, smoking, and frequency of bowel movements and plasma ENL concentration were observed. These data show that foods high in ENL precursors are associated with high concentrations of ENL. Furthermore, smoking, frequent bowel movements, and consumption of fat seems to have a negative affect on the ENL concentration. In conclusion, whole grains and vegetables are the most important dietary providers of plant lignans for the concentration of ENL in Danish postmenopausal women, and if ENL is found to protect against cancer or heart disease, the intake of whole grains and vegetables should be increased. PMID:15465768

  10. Determinants of concentric left ventricular hypertrophy in patients with resistant hypertension: RESIST-POL study.

    PubMed

    Dobrowolski, Piotr; Prejbisz, Aleksander; Klisiewicz, Anna; Florczak, Elżbieta; Rybicka, Justyna; Januszewicz, Andrzej; Hoffman, Piotr

    2015-08-01

    Left ventricular hypertrophy, especially concentric hypertrophy, has been shown to be an independent factor of cardiovascular diseases in patients with hypertension. Obstructive sleep apnea (OSA) and/or metabolic syndrome (MS) are common in patients with resistant hypertension (RHTN). The aim of this study was to evaluate factors associated with concentric hypertrophy in patients with RHTN. Data from 155 patients (92M, 63F) was analyzed. All patients underwent a thorough examination including: biochemical evaluations, ambulatory blood pressure monitoring, polysomnography and echocardiography. MS was defined by The Adult Treatment Panel III. Clinically significant OSA was defined as apnea/hypopnea index (AHI)>15 events per hour. Left ventricular mass index (LVMI) and relative wall thickness (RWT) were calculated. Four types of LV geometry were distinguished based on the LVMI and RWT. Patients were divided into four groups based on the LV geometric patterns: group 1 (normal geometry) (n=38, 24.4%); group 2 (concentric remodeling) (n=40, 25.8%); group 3 (eccentric hypertrophy) (n=26, 16.8%); and group 4 (concentric hypertrophy) (n=51, 33%). MS was found in 64% and OSA (AHI>15) in 43.2% of patients. Factors independently associated with concentric hypertrophy were: age (OR-1.51; 95% CI-1.00-2.27; P<0.04), OSA>15 events per hour (OR-2.73; 95% CI-1.26-5.93; P=0.01) and nighttime systolic blood pressure (SBP) (OR-1.69; 95% CI-1.32-2.17; P=0.0001). Concentric hypertrophy was the most common type of left ventricular disorder in patients with RHTN. Nighttime SBP and clinically significant OSA were independently associated with concentric hypertrophy in patients with RHTN. PMID:25787038

  11. Absolute and Convective Instability of a Liquid Jet in Microgravity

    NASA Technical Reports Server (NTRS)

    Lin, Sung P.; Vihinen, I.; Honohan, A.; Hudman, Michael D.

    1996-01-01

    The transition from convective to absolute instability is observed in the 2.2 second drop tower of the NASA Lewis Research Center. In convective instability the disturbance grows spatially as it is convected downstream. In absolute instability the disturbance propagates both downstream and upstream, and manifests itself as an expanding sphere. The transition Reynolds numbers are determined for two different Weber numbers by use of Glycerin and a Silicone oil. Preliminary comparisons with theory are made.

  12. Biomass Allocation is an Important Determinant of the Tannin Concentration in Growing Plants

    PubMed Central

    Häring, D. A.; Suter, D.; Amrhein, N.; Lüscher, A.

    2007-01-01

    Background and aims Condensed tannins (CTs) in the diet affect consumers in a concentration-dependent manner. Because of their importance in plant defence against herbivores and pathogens as well as their potential application against gastrointestinal parasites of ruminants in agronomy, an understanding of the seasonal dynamics of CT concentrations during plant growth is essential. Methods Over a vegetation period, CT concentrations in leaves, stems and roots and the biomass proportions between these organs were investigated in Onobrychis viciifolia, Lotus corniculatus and Cichorium intybus. Based on the experimental data, a model has been suggested to predict CT concentrations in harvestable biomass of these species. Key Results During the experiment, leaf mass fractions of plants decreased from 85, 64, 85 to 30, 18, 39 % d. wt in Onobrychis, Lotus and Cichorium, respectively, and proportions of stems and roots increased accordingly. While CT concentrations almost doubled in leaves in Onobrychis (from 52 to 86 mg g−1 d. wt, P<0·001) and Lotus (from 25 to 54 mg g−1 d. wt, P<0·001), they were stable at low levels in expanding leaves of Cichorium (5 mg g−1 d. wt) and in stems and roots of all investigated species. Due to an inverse effect of the increasing CT concentrations in leaves and simultaneous dilution from increasing proportions of ‘CT-poor’ stems, CT concentrations in harvestable biomass were stable over time in all investigated species: 62, 26 and 5 mg g−1 d. wt for Onobrychis, Lotus and Cichorium, respectively. Conclusions As a consequence of the unequal distribution of tannins in different plant parts and due to the changing biomass proportions between them, various herbivores (e.g. a leaf-eating insect and a grazing ruminant) may find not only different concentrations of CT in their diets but also different CT dynamics during the season. For the prediction of seasonal variations of CT concentrations, biomass allocation and accumulation

  13. Absolute Antenna Calibration at the US National Geodetic Survey

    NASA Astrophysics Data System (ADS)

    Mader, G. L.; Bilich, A. L.

    2012-12-01

    Geodetic GNSS applications routinely demand millimeter precision and extremely high levels of accuracy. To achieve these accuracies, measurement and instrument biases at the centimeter to millimeter level must be understood. One of these biases is the antenna phase center, the apparent point of signal reception for a GNSS antenna. It has been well established that phase center patterns differ between antenna models and manufacturers; additional research suggests that the addition of a radome or the choice of antenna mount can significantly alter those a priori phase center patterns. For the more demanding GNSS positioning applications and especially in cases of mixed-antenna networks, it is all the more important to know antenna phase center variations as a function of both elevation and azimuth in the antenna reference frame and incorporate these models into analysis software. Determination of antenna phase center behavior is known as "antenna calibration". Since 1994, NGS has computed relative antenna calibrations for more than 350 antennas. In recent years, the geodetic community has moved to absolute calibrations - the IGS adopted absolute antenna phase center calibrations in 2006 for use in their orbit and clock products, and NGS's CORS group began using absolute antenna calibration upon the release of the new CORS coordinates in IGS08 epoch 2005.00 and NAD 83(2011,MA11,PA11) epoch 2010.00. Although NGS relative calibrations can be and have been converted to absolute, it is considered best practice to independently measure phase center characteristics in an absolute sense. Consequently, NGS has developed and operates an absolute calibration system. These absolute antenna calibrations accommodate the demand for greater accuracy and for 2-dimensional (elevation and azimuth) parameterization. NGS will continue to provide calibration values via the NGS web site www.ngs.noaa.gov/ANTCAL, and will publish calibrations in the ANTEX format as well as the legacy ANTINFO

  14. Determination of radon concentration levels in well water in Konya, Turkey.

    PubMed

    Erdogan, M; Eren, N; Demirel, S; Zedef, V

    2013-10-01

    Radon ((222)Rn) measurements were undertaken in 16 samples of well water representing different depths and different types of aquifers found at the city centre of Konya, Central Turkey. The radon activity concentrations of the well water samples collected in the spring and summer seasons of 2012 were measured by using the radon gas analyser (AlphaGUARD PQ 2000PRO). The radon concentrations for spring and summer seasons are 2.29 ± 0.17 to 27.25 ± 1.07 and 1.44 ± 0.18 to 27.45 ± 1.25 Bq l(-1), respectively. The results at hand revealed that the radon concentration levels of the waters strictly depend on the seasons and are slightly variable with depth. Eleven of the 16 well water samples had radon concentration levels below the safe limit of 11.11 Bq l(-1) recommended by the United States Environmental Protection Agency. However, all measured radon concentration levels are well below the 100 Bq l(-1) safe limit declared by the World Health Organisation. The doses resulting from the consumption of these waters were calculated. The calculated minimum and maximum effective doses are 0.29 and 5.49 µSv a(-1), respectively. PMID:23595410

  15. Range of phytoplasma concentrations in various plant hosts as determined by competitive polymerase chain reaction.

    PubMed

    Berges, R; Rott, M; Seemüller, E

    2000-10-01

    ABSTRACT For competitive polymerase chain reaction (PCR), an internal standard DNA template was developed that consisted of a highly conserved, internally deleted 16S rDNA fragment of an aster yellows phytoplasma. The internal standard was calibrated using a quantified culture of Acholeplasma laidlawii. Serial dilutions of the internal standard and fixed amounts of target templates from infected plants were coamplified with the same primers, and the products obtained were quantified using an enzyme-linked immunosorbent assay procedure. Analysis of the data revealed that the phytoplasma concentration in the plants examined differed by a factor of about 4 x 10(6). Phytoplasma concentrations of 2.2 x 10(8) to 1.5 x 10(9) cells per g of tissue were identified in periwinkles infected with various phytoplasmas. High to moderate concentrations were detected in Malus domestica (apple) genotypes infected with the apple proliferation phytoplasma, Alnus glutinosa (alder) genotypes infected with the alder yellows phytoplasma, and most aster yellows-infected Populus (poplar) genotypes examined. Very low phytoplasma concentrations, ranging from 370 to 34,000 cells per g of tissue, were identified in proliferation-diseased apple trees on resistant rootstocks 4551 and 4608, yellows-diseased Quercus robur (oak) trees, and Carpinus betulus (hornbeam) trees. Such low concentrations, which corresponded to about 4 to 340 cells in the reaction mixture, could only be detected and quantified by nested PCR. PMID:18944479

  16. The determinants of hydrogen concentrations in hydrogenated amorphous silicon films prepared using a triode deposition system

    SciTech Connect

    Shimizu, Satoshi; Matsuda, Akihisa; Kondo, Michio

    2007-03-15

    It is important to reduce the hydrogen concentration, in particular, the Si-H{sub 2} bond concentration, in a hydrogenated amorphous silicon film to improve its light-soaking stability. In a previous study, we found that a triode configuration plasma enhanced chemical vapor deposition method provides high quality and a very low hydrogen concentration film; however, the origin of the hydrogen reduction has been unknown. In this article, we investigate the essential factor causing the very low hydrogen concentrations observed in the triode system. In several experiments, we observed strong influences of deposition precursors on the resulting hydrogen concentrations. We propose that due to a steric hindrance, the hydrogen elimination process during film growth is disturbed when higher silane radicals stick to a growth surface. In a triode system, corresponding with the separation of the film growth surface from the precursor generation region, the contribution of higher silane radicals to film growth is suppressed due to their short diffusion length and frequent collisions with silane molecules.

  17. 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

  18. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  19. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  20. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  1. Determination of effect factor for effective parameter on saccharification of lignocellulosic material by concentrated acid

    NASA Astrophysics Data System (ADS)

    Aghili, Sina; Nodeh, Ali Arasteh

    2015-12-01

    Tamarisk usage as a new group of lignocelluloses material to produce fermentable sugars in bio ethanol process was studied. The overall aim of this work was to establish the optimum condition for acid hydrolysis of this new material and a mathematical model predicting glucose release as a function of operation variable. Sulfuric acid concentration in the range of 20 to 60%(w/w), process temperature between 60 to 95oC, hydrolysis time from 120 to 240 min and solid content 5,10,15%(w/w) were used as hydrolysis conditions. HPLC was used to analysis of the product. This analysis indicated that glucose was the main fermentable sugar and was increase with time, temperature and solid content and acid concentration was a parabola influence in glucose production. The process was modeled by a quadratic equation. Curve study and model were found that 42% acid concentration, 15 % solid content and 90oC were optimum condition.

  2. Tetracycline Determines the Conformation of Its Aptamer at Physiological Magnesium Concentrations

    PubMed Central

    Reuss, Andreas J.; Vogel, Marc; Weigand, Julia E.; Suess, Beatrix; Wachtveitl, Josef

    2014-01-01

    Synthetic riboswitches are versatile tools for the study and manipulation of biological systems. Yet, the underlying mechanisms governing its structural properties and regulation under physiological conditions are poorly studied. We performed spectroscopic and calorimetric experiments to explore the folding kinetics and thermodynamics of the tetracycline-binding aptamer, which can be employed as synthetic riboswitch, in the range of physiological magnesium concentrations. The dissociation constant of the ligand-aptamer complex was found to strongly depend on the magnesium concentration. At physiological magnesium concentrations, tetracycline induces a significant conformational shift from a compact, but heterogeneous intermediate state toward the completely formed set of tertiary interactions defining the regulation-competent structure. Thus, the switching functionality of the tetracycline-binding aptamer appears to include both a conformational rearrangement toward the regulation-competent structure and its thermodynamic stabilization. PMID:25517161

  3. Validation of Blubber Progesterone Concentrations for Pregnancy Determination in Three Dolphin Species and a Porpoise

    PubMed Central

    Trego, Marisa L.; Kellar, Nicholas M.; Danil, Kerri

    2013-01-01

    Recent studies have validated the use of biopsies as a minimally invasive way to identify pregnant females in several species of wild cetaceans: Balaenapteraacutorostrata, Delphinusdelphis, Lissodelphisborealis, and Lagenorhynchusobliquidens. These studies found that progesterone (P4) concentrations quantified from blubber attached to biopsy samples is diagnostic of pregnancy. Here we examine a broader group of cetacean species in efforts to investigate how progesterone levels vary between species with respect to pregnancy status. We compared P4 concentrations in blubber collected from fishery bycatch and beach-stranded specimens for 40 females of known reproductive condition from Delphinuscapensis (n = 18), Stenellaattenuata (n = 8), S. longirostris (n = 6), and Phocoenoidesdalli (n = 8). The P4 concentrations were different (t = -7.1, p = 1.79E-08) between pregnant and non-pregnant animals in all species, with the mean blubber P4 concentration for pregnant animals 164 times higher than that of non-pregnant animals. There was no overlap in concentration levels between sexually immature or non-pregnant sexually mature animals and pregnant animals. No significant differences (F = 0.354, p = 0.559) were found between mature non-pregnant and immature D. capensis and Pdalli, suggesting P4 level is not indicative of maturity state in female delphinoids. P4 concentrations in relation to reproductive state were remarkably similar across species. All samples were analyzed with two different enzyme immunoassay kits to gauge assay sensitivity to measure progesterone in small samples, such as biopsies. With the technique now validated for these cetacean species, blubber P4 is a reliable diagnostic of pregnancies across multiple species, and thus expands the utility of this method to study reproduction in free-ranging cetaceans using biopsies. PMID:23936083

  4. Dietary and sociodemographic determinants of bisphenol A urine concentrations in pregnant women and children.

    PubMed

    Casas, Maribel; Valvi, Damaskini; Luque, Noelia; Ballesteros-Gomez, Ana; Carsin, Anne-Elie; Fernandez, Marieta F; Koch, Holger M; Mendez, Michelle A; Sunyer, Jordi; Rubio, Soledad; Vrijheid, Martine

    2013-06-01

    Bisphenol A (BPA) exposure during early life may have endocrine-disrupting effects, but the dietary and sociodemographic predictors of BPA exposure during pregnancy and childhood remain unclear. Our aim was to evaluate the correlations between, and sociodemographic and dietary predictors of, serial urinary BPA concentrations measured during pregnancy and childhood in a Spanish birth cohort study. BPA was measured in two spot urine samples collected from 479 women during the first and third trimester of pregnancy and in one urine sample from their 4-year old children (n=130). Average dietary intakes were reported in food frequency questionnaires during the first and third pregnancy trimester and at age 4years. Multivariate mixed models and linear regression models were used to estimate associations between sociodemographic and dietary factors and BPA concentrations. A small, but statistically significant correlation was found between serial maternal BPA concentrations measured during pregnancy (r=0.17). Pregnant women who were younger, less-educated, smoked, and who were exposed to second-hand tobacco smoke (SHS) had higher BPA concentrations than others. BPA concentrations were also higher in children exposed to SHS. High consumption of canned fish during pregnancy was associated with 21% [GM ratio=1.21; 95%CI 1.02, 1.44] and 25% [GM ratio=1.25; 95%CI 1.05, 1.49] higher urinary BPA concentrations in the first and third pregnancy trimester, respectively, compared to the lowest consumption group. This study suggests that canned fish may be a major source of BPA during pregnancy in Spain, a country of high canned fish consumption. Further evaluation of specific BPA exposure sources in the sociodemographic group of younger women who smoke, are exposed to SHS, and have a low educational level is needed. Studies identifying sources of exposure would benefit from repeat BPA measurements and questionnaires specifically focused on dietary and packaging sources. PMID

  5. Development of a novel noninvasive sensor for determination of blood glucose concentration

    NASA Astrophysics Data System (ADS)

    Boeckle, Stefan; Rovati, Luigi; Ansari, Rafat R.

    2001-10-01

    Optical methods represent the most promising techniques to perform non-invasive glucose detection. Glucose concentration in the aqueous humor closely mimics glucose levels in the blood and therefore non-invasive optical measurement of glucose can be performed by an optical beam crossing the eye anterior chamber. We propose a polarimetric method that exploits the Brewster-reflection of circularly polarized light on the lens of the eye. After reflection, the resulting linearly polarized light is subject to rotation by the glucose in the aqueous humor and thus carries the concentration information. A preliminary experimental setup, using glucose samples in a beaker, was realized and investigated.

  6. Determinants of urinary bisphenol A concentrations in Mexican/Mexican-American pregnant women

    PubMed Central

    Quirós-Alcalá, Lesliam; Eskenazi, Brenda; Bradman, Asa; Ye, Xiaoyun; Calafat, Antonia M.; Harley, Kim

    2013-01-01

    Prenatal exposure to bisphenol A (BPA) may be associated with adverse health effects in the developing fetus; however, little is known about predictors of BPA exposure during pregnancy. We examined BPA exposure in 491 pregnant women from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) cohort and explored the role of living in the United States on significant dietary predictors of BPA exposure. Women provided urine samples up to two times during pregnancy (n=866 total samples). We computed the intraclass correlation coefficient (ICC) to evaluate variability in concentrations between collections and used generalized estimating equation (GEE) models to assess predictors of exposure. Geometric mean (GSD) BPA concentrations were 0.9 (2.8) µg/L and 1.0 (2.6) µg/L at the first and second prenatal visit, respectively. We observed greater within- than between-woman variability in urinary BPA concentrations (ICC=0.22). GEE models suggest that women who lived in the United States their entire life had 38% (CI:−0.1, 89.3) higher urinary BPA concentrations compared with other immigrant women. Additionally, women who consumed ≥3 sodas per day or hamburgers three times a week or more had 58% (CI:18.0, 112.1) and 20% (CI: −0.2, 45.2) higher urinary BPA concentrations, respectively, compared with women who consumed no sodas or hamburgers. A higher percentage of women who lived their entire life in the United States reported increased consumption of sodas and hamburgers compared with other immigrant women. Independent of other factors, BPA urinary concentrations were slightly higher when the sample was collected later in the day. As in previous studies, high within-woman variability in urinary BPA concentrations confirms that several samples are needed to properly characterize exposure during pregnancy. Results also suggest that some factors could be modified to minimize exposures during pregnancy in our study participants (e.g., reducing

  7. Determination of intraluminal theophylline concentrations after oral intake of an immediate- and a slow-release dosage form.

    PubMed

    Brouwers, Joachim; Ingels, Françoise; Tack, Jan; Augustijns, Patrick

    2005-08-01

    The purpose of this study was to evaluate a protocol which enables determining luminal drug concentrations after oral drug administration in man. Human intestinal fluids were aspirated from two sampling sites (duodenum and jejunum) at different time points after oral intake of theophylline; an immediate- and a slow-release dosage form were used to demonstrate the feasibility of discriminating between different formulations. Osmolarity and pH of the aspirates were measured and theophylline concentrations were determined by HPLC-UV. After intake of the immediaterelease formulation of theophylline, duodenal maximum concentrations up to 3 mM were reached within 30 min. Theophylline appeared to be almost completely absorbed before it reached the second sampling site in the jejunum, as observed jejunal concentrations were lower than 10% of the maximal duodenal concentrations. These results are in agreement with fast dissolution and fast absorption through the intestinal mucosa, which could be expected as theophylline belongs to class I of the Biopharmaceutical Classification System. In contrast to the immediate-release formulation, administering the slow-release dosage form resulted in a gradual appearance of theophylline, reaching maximal intestinal concentrations below 300 muM. The proposed methodology can be used to assess luminal drug concentrations and to monitor the time- and site-dependent composition of intestinal fluids after intake of an oral dosage form. This approach may contribute to a better understanding of the behaviour of oral drug formulations in the gastrointestinal tract and may be exploited to further unravel the complexity of the gastrointestinal absorption process. In addition, knowledge of luminal drug concentrations may assist in the selection of drug concentrations applied in in-vitro permeability assays. PMID:16102254

  8. 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

  9. On the Determination of the Critical Level of Market Concentration in Education.

    ERIC Educational Resources Information Center

    Borland, Melvin V.; Howsen, Roy M.

    1993-01-01

    Attempts to estimate a critical level of market concentration within the educational sector for Kentucky. The critical Herfindahl was estimated at 0.50. Counties experiencing a Herfindahl index at or above this number can expect, on average, a 1.6 percentage point decrease (or a 3% reduction) in student achievement scores. (MLH)

  10. Concentration and determinants of molds and allergens in indoor air and house dust of French dwellings.

    PubMed

    Dallongeville, Arnaud; Le Cann, Pierre; Zmirou-Navier, Denis; Chevrier, Cécile; Costet, Nathalie; Annesi-Maesano, Isabella; Blanchard, Olivier

    2015-12-01

    Molds and allergens are common indoor biocontaminants. The aims of this study were to assess the concentrations of common molds in indoor air and floor dust and the concentrations of house dust mite, cat and dog allergens in mattress dust in French dwellings, and to assess predictors of these concentrations. A sample of 150 houses in Brittany (western France) was investigated. Airborne Cladosporium and Penicillium were detected in more than 90% of the dwellings, Aspergillus in 46% and Alternaria in only 6% of the housings. Regarding floor dust samples, Cladosporium and Penicillium were detected in 92 and 80% of the housings respectively, Aspergillus in 49% and Alternaria in 14%. House dust mite allergens Der p1 and Der f1 were detected in 90% and 77% of the mattress dust samples respectively and Can f1 and Fel d1 in 37% and 89% of the homes. Airborne and dustborne mold concentrations, although not statistically correlated (except for Aspergillus) shared most of their predictors. Multivariate linear models for mold levels, explaining up to 62% of the variability, showed an influence of the season, of the age of the dwelling, of aeration habits, presence of pets, smoking, signals of dampness, temperature and relative humidity. Allergens in the dust of the mattress were strongly related to the presence of pets and cleaning practices of bedsheets, these factors accounting for 60% of the variability. This study highlights ubiquitous contamination by molds and underlines complex interaction between outdoor and indoor sources and factors. PMID:26094801

  11. New Analytical Method for the Determination of Detergent Concentration in Water by Fabric Dyeing

    ERIC Educational Resources Information Center

    Seng, Set; Kita, Masakazu; Sugihara, Reiko

    2007-01-01

    The use of harmful organic solvents in classrooms has become a critical issue of concern in the field of chemistry education. This article describes a classroom activity at a high school in which an acrylic fabric was used as the extraction medium in the analysis of the detergent concentration in water instead of organic solvents. Dyes were used…

  12. Qualitative and quantitative methodologies for determination of airborne microorganisms at concentrated animal-feeding operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The generation of bioaerosols from concentrated animal feeding operations (CAFOs) is a concern from a human and animal health perspective. To better understand the airborne microorganisms found in these environments, a number of collection and analytical techniques have been utilized and will be di...

  13. Temperature Compensation in Determining of Remazol Black B Concentrations Using Plastic Optical Fiber Based Sensor

    PubMed Central

    Chong, Su Sin; Aziz, A.R. Abdul; Harun, Sulaiman W.; Arof, Hamzah

    2014-01-01

    In this study, the construction and test of tapered plastic optical fiber (POF) sensors, based on an intensity modulation approach are described. Tapered fiber sensors with different diameters of 0.65 mm, 0.45 mm, and 0.35 mm, were used to measure various concentrations of Remazol black B (RBB) dye aqueous solutions at room temperature. The concentrations of the RBB solutions were varied from 0 ppm to 70 ppm. In addition, the effect of varying the temperature of the RBB solution was also investigated. In this case, the output of the sensor was measured at four different temperatures of 27 °C, 30 °C, 35 °C, and 40 °C, while its concentration was fixed at 50 ppm and 100 ppm. The experimental results show that the tapered POF with d = 0.45 mm achieves the best performance with a reasonably good sensitivity of 61 × 10−4 and a linearity of more than 99%. It also maintains a sufficient and stable signal when heat was applied to the solution with a linearity of more than 97%. Since the transmitted intensity is dependent on both the concentration and temperature of the analyte, multiple linear regression analysis was performed to combine the two independent variables into a single equation. The resulting equation was then validated experimentally and the best agreement between the calculated and experimental results was achieved by the sensor with d = 0.45 mm, where the minimum discrepancy is less than 5%. The authors conclude that POF-based sensors are suitable for RBB dye concentration sensing and, with refinement in fabrication, better results could be achieved. Their low fabrication cost, simple configuration, accuracy, and high sensitivity would attract many potential applications in chemical and biological sensing. PMID:25166498

  14. Determination of sperm concentration using flow cytometry with simultaneous analysis of sperm plasma membrane integrity in zebrafish Danio rerio.

    PubMed

    Yang, Huiping; Daly, Jonathan; Tiersch, Terrence R

    2016-04-01

    Control of sperm concentration is required to ensure consistent and reproducible results for cryopreservation and in vitro fertilization protocols. Determination of sperm concentration is traditionally performed with a counting chamber (e.g., hemocytometer), or more recently with a spectrophotometer. For small-sized biomedical model fishes, the availability of sperm sample is limited to microliters, so it is desirable to develop fast and accurate approaches for concentration determination that also minimize sample use. In this study, a new approach was developed for sperm concentration determination using a flow cytometer (Accuri C6, BD Biosciences, San Jose, CA) with simultaneous measurement of sperm membrane integrity after fluorescent staining with SYBR(®) -14 and propidium iodide (PI) in sperm from Zebrafish Danio rerio. The goal was to develop a protocol for simultaneous determination of sperm quality and quantity by flow cytometry. The objectives were to (1) determine the effects of sample volume (250 and 500 µl) and analysis volume (10 and 50 µl) on the accuracy of particle counting using standard volumetric validation beads; (2) identify the effective range of sperm concentrations that flow cytometry can measure; (3) test the precision and reproducibility of the sperm concentration measurements; and (4) verify the flow cytometry approach by comparison with measurement with a hemocytometer and a microspectrophotometer. Sample volumes of 250 and 500 µl and analysis volumes of 10 and 50 µl did not affect bead count with the factory-set flow rates of "medium" or "fast," and the precision and accuracy was retained across a concentration range of 1 × 10(3) -1 × 10(7) cells/ml. The approach developed in this study was comparable to traditional methodologies such as hemocytometer or microspectrophotometer. This study provides an efficient, accurate, and rapid method for determination of sperm concentration using flow cytometry while providing

  15. Spectroscopic Determination of Triclosan Concentration in a Series of Antibacterial Soaps: A First-Year Undergraduate Laboratory Experiment

    ERIC Educational Resources Information Center

    Wyllie, Graeme R. A.

    2015-01-01

    The antibacterial chemical triclosan is a common component in personal care products but recently the subject of many reports concerning environmental toxicity and health impacts. Although triclosan concentration in a soap can be determined simply via high-performance liquid chromatography, this is a technique not routinely available in the…

  16. 40 CFR 63.7943 - How do I determine the average VOHAP concentration of my remediation material?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... in 40 CFR part 60, appendix A. (2) Analysis. Each collected sample must be prepared and analyzed... according to Method 301 in 40 CFR part 63, appendix A as the basis for knowledge of the material. This... results from a determination of VOHAP concentration using direct measurement by Method 305 in 40 CFR...

  17. 40 CFR 63.7943 - How do I determine the average VOHAP concentration of my remediation material?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in 40 CFR part 60, appendix A. (2) Analysis. Each collected sample must be prepared and analyzed... according to Method 301 in 40 CFR part 63, appendix A as the basis for knowledge of the material. This... results from a determination of VOHAP concentration using direct measurement by Method 305 in 40 CFR...

  18. Determination of size- and number-based concentration of silica nanoparticles in a complex biological matrix by online techniques.

    PubMed

    Bartczak, Dorota; Vincent, Phil; Goenaga-Infante, Heidi

    2015-06-01

    We propose for the first time methodology for the determination of a number-based concentration of silica (SiO2) nanoparticles (NP) in biological serum using nanoparticle tracking analysis (NTA) as the online detector for asymmetric flow field-flow fractionation (AF4). The degree of selectivity offered by AF4 was found necessary to determine reliably number-based concentration of the measured NP in the complex matrix with a relative measurement error of 5.1% (as relative standard deviation, n = 3) and without chemical sample pretreatment. The simultaneous online coupling to other size and concentration detectors, such as multiangle light scattering (MALS) and ICPMS, for the measurement of the same NP suspension, was used to confirm the particle size determined with NTA and the equivalent particle number determined by AF4/NTA, respectively. The size- and number-based concentration data obtained by independent techniques were in a good agreement. The developed methodology can easily be extended to other types of particles or particle suspensions and other complex matrices provided that the particle size is above the limit of detection for NTA. PMID:25970520

  19. The Gellyfish: an in-situ equilibrium-based sampler for determining multiple free metal ion concentrations in marine ecosystems

    EPA Science Inventory

    Free metal ions are usually the most bioavailable and toxic metal species to aquatic organisms, but they are difficult to measure because of their extremely low concentrations in the marine environment. Many of the current methods for determining free metal ions are complicated a...

  20. Using solid-phase microextraction to determine partition coefficients to humic acids and bioavailable concentrations of hydrophobic chemicals

    SciTech Connect

    Ramos, E.U.; Meijer, S.N.; Vaes, W.H.J.; Verhaar, H.J.M.; Hermens, J.L.M.

    1998-11-01

    In the current study, the suitability of negligible depletion solid-phase microextraction (nd-SPME) to determine free fractions of chemicals in aquatic environments was explored. The potential interferences of the dissolved matrix (i.e., humic acids) with the SPME measurements were tested. Results show that nd-SPME measures only the freely dissolved fraction and that the measurements are not disturbed by the humic acids. In addition, nd-SPME was used to determine partition coefficients between dissolved organic carbon and water for four hydrophobic chemicals. Obtained values are in excellent agreement with previously reported data. Finally, the bioaccumulation of hexachlorobenzene and PCB 77 to Daphnia magna was determined in the presence and absence of humic acids. The bioconcentration factors (BCF) were calculated based on total as well as on free concentration. Lower BCF values are obtained in the presence of humic acids using total concentrations, whereas equal BCFs are found using free concentrations measured with nd-SPME. Therefore, the authors can conclude that negligible depletion SPME is a good technique to determine bioavailable concentrations of hydrophobic chemicals in aquatic environments.