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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. Quantitative Determination of Absolute Organohalogen Concentrations in Environmental Samples by X-ray Absorption Spectroscopy

    SciTech Connect

    Leri,A.; Hay, M.; Lanzirotti, A.; Rao, W.; Myneni, S.

    2006-01-01

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

  3. 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

  4. Precise determination of deep trap signatures and their relative and absolute concentrations in semi-insulating GaAs

    NASA Astrophysics Data System (ADS)

    Pavlović, M.; Desnica, U. V.

    1998-08-01

    The new analytical method, simultaneous multiple peak analysis (SIMPA) which comprises simultaneous fitting of whole measured thermally stimulated current (TSC) spectra is presented. The procedure clearly resolves contributions from various overlapping TSC peaks, which results in precise determination of trap parameters (signature) for each trap. In combination with photocurrent temperature dependent measurements, IPC(T), which reflects free carrier lifetime temperature dependence, the estimates of relative and absolute trap concentrations were made as well. The advantage of the SIMPA method in comparison with the single peak approach was demonstrated and analyzed. The SIMPA method was applied to different semi-insulating (SI) GaAs samples, particularly to samples having very high and others having very low deep trap concentrations; and for both extremes excellent fits were achieved. The method also seems very promising for characterization of deep levels and other similar SI materials, like SI InP or SI CdTe.

  5. Absolute concentration measurements inside a jet plume using video digitization

    NASA Astrophysics Data System (ADS)

    Vauquelin, O.

    An experimental system based on digitized video image analysis is used to measure the local value of the concentration inside a plume. Experiments are carried out in a wind-tunnel for a smoke-seeded turbulent jet plume illuminated with a laser beam. Each test is filmed, subsequently video images are digitized and analysed in order to determine the smoke absolute concentration corresponding to each pixel gray level. This non-intrusive measurement technique is first calibrated and different laws connecting gray level to concentration are established. As a first application, concentration measurements are made inside a turbulent jet plume and compared with measurements conducted using a classic gas analysis method. We finally present and discuss the possibilities offered for the measurements of absolute concentration fluctuations.

  6. Determining Absolute Zero Using a Tuning Fork

    NASA Astrophysics Data System (ADS)

    Goldader, Jeffrey D.

    2008-04-01

    The Celsius and Kelvin temperature scales, we tell our students, are related. We explain that a change in temperature of 1°C corresponds to a change of 1 Kelvin and that atoms and molecules have zero kinetic energy at zero Kelvin, -273°C. In this paper, we will show how students can derive the relationship between the Celsius and Kelvin temperature scales using a simple, well-known physics experiment. By making multiple measurements of the speed of sound at different temperatures, using the classic physics experiment of determining the speed of sound with a tuning fork and variable-length tube, they can determine the temperature at which the speed of sound is zero—absolute zero.

  7. Influence of physical and chemical properties of HTSXT-FTIR samples on the quality of prediction models developed to determine absolute concentrations of total proteins, carbohydrates and triglycerides: a preliminary study on the determination of their absolute concentrations in fresh microalgal biomass.

    PubMed

    Serrano León, Esteban; Coat, Rémy; Moutel, Benjamin; Pruvost, Jérémy; Legrand, Jack; Gonçalves, Olivier

    2014-11-01

    Absolute concentrations of total macromolecules (triglycerides, proteins and carbohydrates) in microorganisms can be rapidly measured by FTIR spectroscopy, but caution is needed to avoid non-specific experimental bias. Here, we assess the limits within which this approach can be used on model solutions of macromolecules of interest. We used the Bruker HTSXT-FTIR system. Our results show that the solid deposits obtained after the sampling procedure present physical and chemical properties that influence the quality of the absolute concentration prediction models (univariate and multivariate). The accuracy of the models was degraded by a factor of 2 or 3 outside the recommended concentration interval of 0.5-35 µg spot(-1). Change occurred notably in the sample hydrogen bond network, which could, however, be controlled using an internal probe (pseudohalide anion). We also demonstrate that for aqueous solutions, accurate prediction of total carbohydrate quantities (in glucose equivalent) could not be made unless a constant amount of protein was added to the model solution (BSA). The results of the prediction model for more complex solutions, here with two components: glucose and BSA, were very encouraging, suggesting that this FTIR approach could be used as a rapid quantification method for mixtures of molecules of interest, provided the limits of use of the HTSXT-FTIR method are precisely known and respected. This last finding opens the way to direct quantification of total molecules of interest in more complex matrices.

  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.

  10. The Multispecimen Method for Absolute Paleointensity Determination

    NASA Astrophysics Data System (ADS)

    Dekkers, M. J.; de Groot, L. V.; Monster, M.

    2015-12-01

    Paleointensity methods have seen a large improvement in the 21th century. This included optimizing classic Thellier-style protocols along with establishing stringent sets of quality criteria, developing microwave excitation as an alternative to thermal treatment, selecting sample material that contains the most suitable remanence carriers (i.e. single domain magnetic particles), calibrating non-heating paleointensity methods, and the introduction of the multispecimen paleointensity (MSP) protocol. An MSP experiment is carried out at one specific temperature selected to avoid thermochemical alteration; a series of specimens is heated and cooled in various applied furnace fields oriented parallel to the specimen's NRM. The furnace field value at which no change in NRM occurs is the paleofield. While the rationale of the MSP approach is surprisingly straightforward, some of the original claims (Dekkers and Böhnel, 2006) are by now shown to be untenable. This pertains to the claimed domain state independence in the original MSP method, although the Fabian and Leonhardt (2010) extended protocol largely corrects for domain state effects. Here we describe the optimal workflow for MSP experiments derived from our collection of historic flows from four volcanic edifices: Mt. Etna, Hawaii, the Canary Islands, and the Azores. By comparing the experimental outcome derived from historic flows with known paleointensities we found that technically acceptable experiments may yield overestimates, correct determinations, as well as underestimates of the paleofield. The so-called "ARM test" (de Groot et al., 2012) can distinguish between those three options. Based on TRM and ARM being analogues, this test compares ARM acquisition curves of sister samples before and after heating to the MSP experiment temperature. Simulated paleointensity experiments following this workflow consistently deliver the correct answer (Monster et al., submitted).

  11. Stochastic analysis of biochemical reaction networks with absolute concentration robustness

    PubMed Central

    Anderson, David F.; Enciso, Germán A.; Johnston, Matthew D.

    2014-01-01

    It has recently been shown that structural conditions on the reaction network, rather than a ‘fine-tuning’ of system parameters, often suffice to impart ‘absolute concentration robustness’ (ACR) on a wide class of biologically relevant, deterministically modelled mass-action systems. We show here that fundamentally different conclusions about the long-term behaviour of such systems are reached if the systems are instead modelled with stochastic dynamics and a discrete state space. Specifically, we characterize a large class of models that exhibit convergence to a positive robust equilibrium in the deterministic setting, whereas trajectories of the corresponding stochastic models are necessarily absorbed by a set of states that reside on the boundary of the state space, i.e. the system undergoes an extinction event. If the time to extinction is large relative to the relevant timescales of the system, the process will appear to settle down to a stationary distribution long before the inevitable extinction will occur. This quasi-stationary distribution is considered for two systems taken from the literature, and results consistent with ACR are recovered by showing that the quasi-stationary distribution of the robust species approaches a Poisson distribution. PMID:24522780

  12. Absolute configuration determination of angular dihydrocoumarins from Peucedanum praeruptorum.

    PubMed

    Lou, Hong-Xiang; Sun, Long-Ru; Yu, Wen-Tao; Fan, Pei-Hong; Cui, Lei; Gao, Yan-Hui; Ma, Bin; Ren, Dong-Mei; Ji, Mei

    2004-09-01

    From Peucedanum praeruptorum, one new khellactone ester (3'R)-O-acetyl-(4'S)-O-angeloylkhellactone (3), as well as four known angular dihydropyranocoumarins (1, 2, 4, 5) have been isolated. On the basis of NMR spectra and X-ray crystallography, their structures were determined. We have elucidated their absolute configuration by either chiral separation of their alkaline hydrolysis products with Rp-18 HPLC eluted with 5% hydroxypropyl-beta-cyclodextrin (beta-HCD) or by measurement of their CD spectra. A general rule relating the position and absolute streochemistry of the khellactone esters to the sign of their Cotton effects in CD curves is proposed.

  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. Absolute configuration determination using enantiomeric pairs of molecularly imprinted polymers.

    PubMed

    Meador, Danielle S; Spivak, David A

    2014-03-07

    A new method for determination of absolute configuration (AC) is demonstrated using an enantiomeric pair of molecularly imprinted polymers, referred to as "DuoMIPs". The ratio of HPLC capacity factors (k') for the analyte on each of the DuoMIPs is defined as the γ factor and can be used to determine AC when above 1.2. A mnemonic based on the complementary binding geometry of the DuoMIPs was used to aid in understanding and prediction of AC.

  15. Absolute Quantitation of Water and Metabolites in the Human Brain. II. Metabolite Concentrations

    NASA Astrophysics Data System (ADS)

    Kreis, R.; Ernst, T.; Ross, B. D.

    A method for determining absolute metabolite concentrations with in vivo1H magnetic resonance spectroscopy is presented. Using the compartmentation model introduced in the preceding paper of this series ( J. Magn. Reson. B102, 1, 1993), it is possible to express NMR results in terms of most commonly used concentration units. The proposed scheme, involving the measurement of an external standard as well as of the localized water signal, is verified on cerebral spectra obtained from 22 subjects. Besides concentrations, longitudinal and transverse relaxation times are determined for parietal white and occipital gray matter. The determination of these quantities crucially depends on the analysis of the T2 signal decay as a function of echo time. The in vivo concentrations of the four metabolites N-acetyl aspartate, creatine plus phosphocreatine, choline, and myo-inositol are in good agreement with biochemical determinations performed in vitro. Two clinical examples emphasize the relevance of absolute quantitation in the investigation of human neuropathology and normal development.

  16. 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.

  17. Crystal structure of meteoritic schreibersites: determination of absolute structure

    NASA Astrophysics Data System (ADS)

    Skála, Roman; Císařová, Ivana

    Minerals of the schreibersite nickelphosphide series (Fe,Ni)3P crystallize in the non-centrosymmetric space group Ibar 4. As a consequence, they can possess two different spatial arrangements of the constituting atoms within the unit cell, related by the inversion symmetry operation. Here, we present the crystal structure refinements from single crystal X-ray diffraction data for schreibersite grains from iron meteorites Acuña, Carlton, Hex River Mts. (three different crystals), Odessa (two different crystals), Sikhote Alin, and Toluca aiming for the determination of the absolute structure of the examined crystals. The crystals studied cover the composition range from 58 mol% to 80 mol% Fe3P end-member. Unit-cell parameter a and volume of the unit cell V, as well as certain topological structural parameters tightly correlate with Fe3P content. Unit-cell parameter c, on the other hand, does not show such strong correlation. Eight of the nine crystal structure refinements allowed unambiguous absolute structure assignment. The single crystal extracted from Toluca is, however, of poor quality and consequently the structure refinement did not provide as good results as the rest of the materials. Also, this crystal has only weak inversion distinguishing power to provide unequivocal absolute structure determination. Six of the eight unambiguous absolute structure determinations indicated inverted atomic arrangement compared to that reported in earlier structure refinements (here called standard). Only two grains, one taken from Odessa iron and the other from the Hex River Mts. meteorite, reveal the dominance of standard crystal structure setting.

  18. Absolute measurements of the uranium concentration in thick samples using fission-track detectors

    NASA Astrophysics Data System (ADS)

    Enkelmann, Eva; Jonckheere, Raymond; Ratschbacher, Lothar

    2005-04-01

    We propose an improved equation for calculating the uranium concentration in thick samples based on induced fission-track counts in an external detector that takes into consideration (1) the fission-fragment ranges in the sample and external detector, (2) the etchable track length and (3) the track counting efficiency in the external detector. The values of these parameters have been determined by calculation and experiment and are shown to have a significant effect on the calculated uranium concentrations. The new equation was tested by calculating the uranium concentrations in standard uranium glasses (CN-5; IRMM-540R) and apatite samples (Durango; horse tooth) in which the uranium content was also determined with independent methods (INAA; ENAA; TIMS). The results show that: (1) accurate measurements with the fission-track method are feasible within a broad range of uranium concentrations and (2) uranium determinations based on standards are only accurate if the standard and sample are made of the same material. Because the absolute fission-tack dating method is also based on accurate thermal neutron fluence measurements and similar correction factors for the track registration and counting efficiencies, this study provides a strong endorsement for the fact that absolute fission-track ages are accurate.

  19. 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.

  20. Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

    PubMed

    Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

    2015-10-20

    Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 μm apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration.

  1. Automatic section thickness determination using an absolute gradient focus function.

    PubMed

    Elozory, D T; Kramer, K A; Chaudhuri, B; Bonam, O P; Goldgof, D B; Hall, L O; Mouton, P R

    2012-12-01

    Quantitative analysis of microstructures using computerized stereology systems is an essential tool in many disciplines of bioscience research. Section thickness determination in current nonautomated approaches requires manual location of upper and lower surfaces of tissue sections. In contrast to conventional autofocus functions that locate the optimally focused optical plane using the global maximum on a focus curve, this study identified by two sharp 'knees' on the focus curve as the transition from unfocused to focused optical planes. Analysis of 14 grey-scale focus functions showed, the thresholded absolute gradient function, was best for finding detectable bends that closely correspond to the bounding optical planes at the upper and lower tissue surfaces. Modifications to this function generated four novel functions that outperformed the original. The 'modified absolute gradient count' function outperformed all others with an average error of 0.56 μm on a test set of images similar to the training set; and, an average error of 0.39 μm on a test set comprised of images captured from a different case, that is, different staining methods on a different brain region from a different subject rat. We describe a novel algorithm that allows for automatic section thickness determination based on just out-of-focus planes, a prerequisite for fully automatic computerized stereology.

  2. Using Absolute Humidity and Radiochemical Analyses of Water Vapor Samples to Correct Underestimated Atmospheric Tritium Concentrations

    SciTech Connect

    Eberhart, C.F.

    1999-06-01

    Los Alamos National Laboratory (LANL) emits a wide variety of radioactive air contaminants. An extensive ambient air monitoring network, known as AIRNET, is operated on-site and in surrounding communities to estimate radioactive doses to the public. As part of this monitoring network, water vapor is sampled continuously at more than 50 sites. These water vapor samples are collected every two weeks by absorbing the water vapor in the sampled air with silica gel and then radiochemically analyzing the water for tritium. The data have consistently indicated that LANL emissions cause a small, but measurable impact on local concentrations of tritium. In early 1998, while trying to independently verify the presumed 100% water vapor collection efficiency, the author found that this efficiency was normally lower and reached a minimum of 10 to 20% in the middle of summer. This inefficient collection was discovered by comparing absolute humidity (g/m{sup 3}) calculated from relative humidity and temperature to the amount of water vapor collected by the silica gel per cubic meter of air sampled. Subsequent experiments confirmed that the elevated temperature inside the louvered housing was high enough to reduce the capacity of the silica gel by more than half. In addition, their experiments also demonstrated that, even under optimal conditions, there is not enough silica gel present in the sampling canister to absorb all of the moisture during the higher humidity periods. However, there is a solution to this problem. Ambient tritium concentrations have been recalculated by using the absolute humidity values and the tritium analyses. These recalculated tritium concentrations were two to three times higher than previously reported. Future tritium concentrations will also be determined in the same manner. Finally, the water vapor collection process will be changed by relocating the sampling canister outside the housing to increase collection efficiency and, therefore

  3. Determination of Absolute Zero Using a Computer-Based Laboratory

    ERIC Educational Resources Information Center

    Amrani, D.

    2007-01-01

    We present a simple computer-based laboratory experiment for evaluating absolute zero in degrees Celsius, which can be performed in college and undergraduate physical sciences laboratory courses. With a computer, absolute zero apparatus can help demonstrators or students to observe the relationship between temperature and pressure and use…

  4. Yeast AMP-activated Protein Kinase Monitors Glucose Concentration Changes and Absolute Glucose Levels*

    PubMed Central

    Bendrioua, Loubna; Smedh, Maria; Almquist, Joachim; Cvijovic, Marija; Jirstrand, Mats; Goksör, Mattias; Adiels, Caroline B.; Hohmann, Stefan

    2014-01-01

    Analysis of the time-dependent behavior of a signaling system can provide insight into its dynamic properties. We employed the nucleocytoplasmic shuttling of the transcriptional repressor Mig1 as readout to characterize Snf1-Mig1 dynamics in single yeast cells. Mig1 binds to promoters of target genes and mediates glucose repression. Mig1 is predominantly located in the nucleus when glucose is abundant. Upon glucose depletion, Mig1 is phosphorylated by the yeast AMP-activated kinase Snf1 and exported into the cytoplasm. We used a three-channel microfluidic device to establish a high degree of control over the glucose concentration exposed to cells. Following regimes of glucose up- and downshifts, we observed a very rapid response reaching a new steady state within less than 1 min, different glucose threshold concentrations depending on glucose up- or downshifts, a graded profile with increased cell-to-cell variation at threshold glucose concentrations, and biphasic behavior with a transient translocation of Mig1 upon the shift from high to intermediate glucose concentrations. Fluorescence loss in photobleaching and fluorescence recovery after photobleaching data demonstrate that Mig1 shuttles constantly between the nucleus and cytoplasm, although with different rates, depending on the presence of glucose. Taken together, our data suggest that the Snf1-Mig1 system has the ability to monitor glucose concentration changes as well as absolute glucose levels. The sensitivity over a wide range of glucose levels and different glucose concentration-dependent response profiles are likely determined by the close integration of signaling with the metabolism and may provide for a highly flexible and fast adaptation to an altered nutritional status. PMID:24627493

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

    PubMed

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

    2016-07-01

    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.

  6. 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

  7. The use of X-ray crystallography to determine absolute configuration.

    PubMed

    Flack, H D; Bernardinelli, G

    2008-05-15

    Essential background on the determination of absolute configuration by way of single-crystal X-ray diffraction (XRD) is presented. The use and limitations of an internal chiral reference are described. The physical model underlying the Flack parameter is explained. Absolute structure and absolute configuration are defined and their similarities and differences are highlighted. The necessary conditions on the Flack parameter for satisfactory absolute-structure determination are detailed. The symmetry and purity conditions for absolute-configuration determination are discussed. The physical basis of resonant scattering is briefly presented and the insights obtained from a complete derivation of a Bijvoet intensity ratio by way of the mean-square Friedel difference are exposed. The requirements on least-squares refinement are emphasized. The topics of right-handed axes, XRD intensity measurement, software, crystal-structure evaluation, errors in crystal structures, and compatibility of data in their relation to absolute-configuration determination are described. Characterization of the compounds and crystals by the physicochemical measurement of optical rotation, CD spectra, and enantioselective chromatography are presented. Some simple and some complex examples of absolute-configuration determination using combined XRD and CD measurements, using XRD and enantioselective chromatography, and in multiply-twinned crystals clarify the technique. The review concludes with comments on absolute-configuration determination from light-atom structures.

  8. 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.

  9. Determination of the absolute configuration of a novel dipeptide isostere.

    PubMed

    Lynch, V M; Austin, R E; Martin, S F; George, T

    1991-06-15

    (1R-[1 alpha(1R*,2R*,3S*),2 beta,5 alpha])-2-(4-Morpholinocarbonyl)- 3-phenylcyclopropane 2-(1-methyl-ethyl)-5-methylcyclohexyl ester, C25H35NO4, Mr = 413 x 56, orthorhombic, P2(1)2(1)2(1), a = 9 x 359 (2), b = 10 x 1172 (14), c = 24 x 710 (4) A, V = 2339 x 8 (6) A3, Z = 4, Dx = 1 x 17 g cm-3, mu = 0 x 7332 cm-1, Mo K alpha radiation, lambda = 0 x 7107 A, F(000) = 896, T = 198 K, R = 0 x 0475 for 2460 reflections [Fo greater than or equal to 4 sigma(Fo)]. The assignment of the absolute configuration was based on internal comparison to the (-)-menthol moiety. The morpholenyl and cyclohexyl rings are in the chair conformation. The amide group is essentially planar [max. deviation 0.025 (2) A for N19] resulting in a close non-bonded contact between the amide oxygen, O18, and H24a of 2 x 24 (4) A.

  10. 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.

  11. 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.

  12. 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)

  13. 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…

  14. Crystallization of an achiral cyclohexanone ethylene ketal in enantiomorphs and determination of the absolute structure.

    PubMed

    Graus, Sara; Tejedor, Rosa M; Uriel, Santiago; Serrano, José Luis; Alkorta, Ibon; Elguero, José

    2010-06-16

    The achiral 4-methoxy-4-(p-methoxyphenyl)-cyclohexanone ethylene ketal (1) resolves spontaneously. The crystal structure is solved in chiral spatial group P2(1). Because compound 1 is composed of only light atoms (C, H, O) it is not possible to determine its absolute structure configuration. An efficient procedure for the absolute structure configuration determination of flexible molecules containing only light atoms is proposed, based on the combination of X-ray diffraction, solid-state VCD, and DFT calculations.

  15. 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.

  16. Determining Absolute Polarization of Ultracold Neutrons in the UCNA Experiment

    NASA Astrophysics Data System (ADS)

    Dees, Eric; UCNA Collaboration

    2016-09-01

    The UCNA experiment uses the decay of trapped ultracold neutrons (UCN) to measure the angular correlation A between the emitted electron's momentum and the direction of the neutron's spin. For a precision measurement of A, a similarly precise determination of the equilibrium neutron polarization is required. By utilizing UCN, transport through a large (7T) B field provides 100 % polarization, and a spin flipper allows state selection during loading phases. This spin flipper also measures the equilibrium polarization of the UCN population present in the spectrometer, after each hour-long beta-counting cycle. By including a neutron reflecting shutter the leading uncertainty in polarimetry measurements prior to 2011, resulting from the residual background population, was reduced to near zero. However, this modification also introduces new systematic corrections, requiring new run types to quantify. Among these corrections are effects from the spin flipper efficiency, spectral velocity conditioning, and depolarization feeding. We will review the analytic underpinning for these contributions, discuss additional measurements required to quantify these parameters, and present a Monte-Carlo analysis to determine the corrected depolarized fraction, and associated uncertainty. Supported by NSF and DOE.

  17. 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.

  18. VCD to determine absolute configuration of natural product molecules: secolignans from Peperomia blanda.

    PubMed

    Felippe, Lidiane G; Batista, João M; Baldoqui, Debora C; Nascimento, Isabele R; Kato, Massuo J; He, Yanan; Nafie, Laurence A; Furlan, Maysa

    2012-06-07

    The absolute configuration and solution-state conformers of three peperomin-type secolignans isolated from Peperomia blanda (Piperaceae) are unambiguously determined by using vibrational circular dichroism (VCD) spectroscopy associated with density functional theory (DFT) calculations. Advantages of VCD over the electronic form of CD for the analysis of diastereomers are also discussed. This work extends our growing knowledge about secondary metabolites within the Piperaceae family species while providing a definitive and straightforward method to assess the absolute stereochemistry of secolignans.

  19. Spectrophotometric determination of protein concentration.

    PubMed

    Simonian, Michael H

    2004-09-01

    This unit describes spectrophotometric and colorimetric methods for measuring the concentration of a sample protein in solution. Absorbance measured at 280 nm (A(280)) is used to calculate protein concentration by comparison with a standard curve or published absorptivity values for that protein (a(280)). Alternatively, absorbance measured at 205 nm (A(205)) is used to calculate the protein concentration. The A(280) and A(205) methods can be used to quantify total protein in crude lysates and purified or partially purified protein. A spectrofluorometer or a filter fluorometer can be used to measure the intrinsic fluorescence emission of a sample solution; this value is compared with the emissions from standard solutions to determine the sample concentration. The fluorescence emission method is used to quantify purified protein. This simple method is useful for dilute protein samples and can be completed in a short amount of time. There are two colorimetric methods: the Bradford colorimetric method, based upon binding of the dye Coomassie brilliant blue to the protein of interest, and the Lowry method, which measures colorimetric reaction of tyrosyl residues in the protein sample.

  20. Measurement of the absolute CF2 concentration in a dielectric barrier discharge running in argon/fluorocarbon mixtures

    NASA Astrophysics Data System (ADS)

    Vinogradov, I. P.; Dinkelmann, A.; Lunk, A.

    2004-11-01

    The role of different CFx-radicals in plasma polymerization in fluorocarbon mixtures has not been determined yet. Therefore spectroscopic investigations of dielectric barrier discharges (DBDs) in argon/fluorocarbon mixtures at atmospheric pressure were conducted with the focus on measurement of the concentration of CFx-radicals. The following diagnostic procedures were applied: FTIR absorption spectroscopy to diagnose stable compounds in the discharge, optical emission spectroscopy of the DBD in the UV and visible range and measurement of the CF2 concentration by UV absorption spectroscopy. The DBD was running in argon with the following admixtures: CF4, C2F6, C2H2F4, C3F8, C3HF7, c-C4F8. The relative concentration of the CF3-radical and the absolute concentration of CF2 in Ar/fluorocarbon mixtures were measured by emission spectroscopy and by absorption and emission spectroscopy, respectively. Emission and absorption spectroscopy were performed simultaneously in combination with electrical measurements of the discharge characteristics. The influence of small amounts of hydrogen or oxygen added to the argon/fluorocarbon mixtures was investigated.

  1. 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…

  2. 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,…

  3. 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...

  4. 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.

  5. Absolute determination of cross sections for resonant Raman scattering on silicon

    NASA Astrophysics Data System (ADS)

    Müller, Matthias; Beckhoff, Burkhard; Ulm, Gerhard; Kanngießer, Birgit

    2006-07-01

    We studied the resonant Raman scattering of x rays in the vicinity of the K absorption edge of silicon. The investigation was carried out at the plane grating monochromator beamline for undulator radiation of the PTB laboratory at BESSY II in Berlin. Cross sections were determined absolutely for a wide energy range of incident photons with small relative uncertainties employing calibrated instrumentation avoiding any reference samples. The experimentally determined values differ clearly from the theoretical ones found in the literature.

  6. 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.

  7. 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

  8. Determination of absolute configuration of chiral molecules using vibrational optical activity: a review.

    PubMed

    He, Yanan; Wang, Bo; Dukor, Rina K; Nafie, Laurence A

    2011-07-01

    Determination of the absolute handedness, known as absolute configuration (AC), of chiral molecules is an important step in any field related to chirality, especially in the pharmaceutical industry. Vibrational optical activity (VOA) has become a powerful tool for the determination of the AC of chiral molecules in the solution state after nearly forty years of evolution. VOA offers a novel alternative, or supplement, to X-ray crystallography, permitting AC determinations on neat liquid, oil, and solution samples without the need to grow single crystals of the pure chiral sample molecules as required for X-ray analysis. By comparing the sign and intensity of the measured VOA spectrum with the corresponding ab initio density functional theory (DFT) calculated VOA spectrum of a chosen configuration, one can unambiguously assign the AC of a chiral molecule. Comparing measured VOA spectra with calculated VOA spectra of all the conformers can also provide solution-state conformational populations. VOA consists of infrared vibrational circular dichroism (VCD) and vibrational Raman optical activity (ROA). Currently, VCD is used routinely by researchers in a variety of backgrounds, including molecular chirality, asymmetric synthesis, chiral catalysis, drug screening, pharmacology, and natural products. Although the application of ROA in AC determination lags behind that of VCD, with the recent implementation of ROA subroutines in commercial quantum chemistry software, ROA will in the future complement VCD for AC determination. In this review, the basic principles of the application of VCD to the determination of absolute configuration in chiral molecules are described. The steps required for VCD spectral measurement and calculation are outlined, followed by brief descriptions of recently published papers reporting the determination of AC in small organic, pharmaceutical, and natural product molecules.

  9. System for determining biofuel concentration

    DOEpatents

    Huff, Shean P.; Janke, Christopher James; Kass, Michael D.; Lewis, Sr, Samuel Arthur; Pawel, Steven J; Theiss, Timothy J.

    2016-09-13

    A measurement device or system configured to measure the content of biofuels within a fuel blend. By measuring a state of a responsive material within a fuel blend, a biofuel content of the fuel blend may be measured. For example, the solubility of a responsive material to biofuel content within a fuel blend, may affect a property of the responsive material, such as shape, dimensional size, or electrical impedance, which may be measured and used as a basis for determining biofuel content.

  10. 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.

  11. Interferometric determination of the topographies of absolute sphere radii using the sphere interferometer of PTB

    NASA Astrophysics Data System (ADS)

    Bartl, Guido; Krystek, Michael; Nicolaus, Arnold; Giardini, Walter

    2010-11-01

    This paper presents a method to reconstruct the absolute shape of a sphere—i.e. a topography of radii—using the sphere interferometer of PTB in combination with a stitching approach. The method allows for the reconstruction of absolute radii instead of the relative shape deviations which result from conventional sphericity measurements. The sphere interferometer was developed for the volume determination of spherical material measures—in particular the spheres of the Avogadro project—by precise diameter measurements with an uncertainty of 1 nm or less. In the scope of the present work a procedure has been implemented that extends the applicability of the interferometer to fields where not the volume or diameter but the direction-dependent radii are of interest. The results of the reconstruction were compared quantitatively to the independent results of sphericity measurements from CSIRO.

  12. Electrochemical considerations for determining absolute frontier orbital energy levels of conjugated polymers for solar cell applications.

    PubMed

    Cardona, Claudia M; Li, Wei; Kaifer, Angel E; Stockdale, David; Bazan, Guillermo C

    2011-05-24

    Narrow bandgap conjugated polymers in combination with fullerene acceptors are under intense investigation in the field of organic photovoltaics (OPVs). The open circuit voltage, and thereby the power conversion efficiency, of the devices is related to the offset of the frontier orbital energy levels of the donor and acceptor components, which are widely determined by cyclic voltammetry. Inconsistencies have appeared in the use of the ferrocenium/ferrocene (Fc + /Fc) redox couple, as well as the values used for the absolute potentials of standard electrodes, which can complicate the comparison of materials properties and determination of structure/property relationships.

  13. Dirhodium complexes: determination of absolute configuration by the exciton chirality method using VCD spectroscopy.

    PubMed

    Szilvágyi, Gábor; Brém, Balázs; Báti, Gábor; Tölgyesi, László; Hollósi, Miklós; Vass, Elemér

    2013-09-28

    Inherently chiral dinuclear rhodium complexes have been synthesized from the well-known dirhodium(II)-acetate and chiral/achiral amino acids. These complexes have a twisted paddlewheel structure due to axial chirality. Chiral induction could be observed when the ligands were chiral, opposite to the case of achiral ligands, where a racemic mixture was formed. The racemic mixture was separated by chiral HPLC-ECD. The stereochemical properties of these complexes were determined by VCD spectroscopy supported by theoretical calculations at the DFT level. We present a simple route to determine the absolute configuration by an exciton chirality method using VCD spectroscopy.

  14. Measurement of Absolute Hydroxyl Radical Concentration in Lean Fuel-Air Mixtures Excited by Nanosecond Pulsed Discharge.

    NASA Astrophysics Data System (ADS)

    Yin, Z.; Lempert, W. R.; Adamovich, I. V.

    2013-06-01

    The focus in plasma assisted combustion research has been on the evaluation of conventional plasma/combustion mechanisms in predicting oxidation and ignition processes initiated and/or sustained by non-equilibrium, nanosecond discharges. Accurate quantitative data such as temperature and species concentration are needed for assessing and improving numerical modeling. As an important intermediate species, the concentration of hydroxyl radical (OH) is very sensitive to the combustion environment (e.g., temperature, equivalence ratio), and therefore is of great interest to kinetic study. In this work, Laser-Induced Fluorescence (LIF) was used for time-resolved temperature and OH number density measurements in lean H_2-, CH_4-, C_2H_4-, and C_3H_8- air mixtures in a plasma flow reactor inside a tube furnace. The premixed fuel-air flow in the reactor, initially at T_0=500 K and P=100 torr, was excited by a burst of repetitive nanosecond electric pulses in a dielectric-barrier plane-to-plane geometry (˜28 kV peak voltage and ˜5 nsec pulse width, estimated 1.25 mJ/pulse coupled energy). Laser was timed to probe after the discharge burst was over to avoid strong plasma emission interference. Relative fluorescence signal was put on an absolute scale by calibrating against Rayleigh scattering signal in the same flow reactor. Experimental results were compared to predictions from a 0-D plasma/combustion chemistry model employing several well-established combustion mechanisms. 2-D temperature and OH concentration distributions in the discharge volume were obtained by planar LIF and was used to quantitatively evaluate plasma uniformity in the reactor. These results were used to determine the validity of the 0-D model. thanks

  15. 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

  16. 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.

  17. Determination of Absolute Coverages for Small Aliphatic Alcohols on TiO2(110)

    SciTech Connect

    Li, Zhenjun; Smith, R. Scott; Kay, Bruce D.; Dohnalek, Zdenek

    2011-11-17

    The absolute coverages of water and small aliphatic alcohols (C1-C4) were determined on TiO{sub 2}(110) using a combination of temperature programmed desorption and liquid nitrogen cooled quartz crystal microbalance measurements. The absolute saturation coverages of water on Ti{sup 4+} and bridging oxygen (O{sub b}) sites are found to be equal to 1 monolayer with respect to the number of Ti{sup 4+} and/or O{sub b} sites (1 ML {triple_bond} 5.2 x 10{sup 14} cm{sup 2}) in a good agreement with prior studies. The saturation coverages of primary alcohols on Ti{sup 4+} sites are found to be approximately constant and equal to 0.77 ML. This indicates that the increasing length of the alkyl chains does not contribute to additional steric hindrance. Additional steric hindrance is observed with increasing number of chains as shown for secondary alcohols and tertiary t-butanol where the coverage decreases to 0.62 and 0.44 ML, respectively. On O{sub b} rows, a monotonic decrease of the alcohol coverage is observed for both increasing length of the alkyl chains and the chain number.

  18. The determination of the absolute configurations of chiral molecules using vibrational circular dichroism (VCD) spectroscopy.

    PubMed

    Stephens, Philip J; Devlin, Frank J; Pan, Jian-Jung

    2008-05-15

    The vibrational circular dichroism (VCD) spectra of the two enantiomers of a chiral molecule are of equal magnitude and opposite sign: i.e. mirror-image enantiomers give mirror-image VCD spectra. In principle, the absolute configuration (AC) of a chiral molecule can therefore be determined from its VCD spectrum. In practice, the determination of the AC of a chiral molecule from its experimental VCD spectrum requires a methodology which reliably predicts the VCD spectra of its enantiomers. The only reliable methodology developed to date uses the Stephens quantum-mechanical theory of the rotational strengths of fundamental vibrational transitions, developed in the early 1980s, implemented using ab initio density functional theory in the GAUSSIAN program in the mid 1990s. This methodology has by now been widely used in determining ACs from experimental VCD spectra. In this article we discuss the protocol for determining the ACs of chiral molecules with optimum reliability and its implementation for a variety of molecules, including the D3 symmetry perhydrotriphenylene, a thiazino-oxadiazolone recently shown to be a highly active calcium entry channel blocker, the alkaloid natural products schizozygine, iso-schizogaline, and iso-schizogamine, and the iridoid natural products plumericin, iso-plumericin, and prismatomerin. The power of VCD spectroscopy in determining ACs, even for large organic molecules and for substantially conformationally-flexible organic molecules is clearly documented.

  19. 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.

  20. The Br+HO 2 reaction revisited: Absolute determination of the rate constant at 298 K

    NASA Astrophysics Data System (ADS)

    Laverdet, G.; Le Bras, G.; Mellouki, A.; Poulet, G.

    1990-09-01

    The absolute determination of the rate constant for the reaction Br+HO 2→HBr+O 2 has been done at 298 K using the discharge-flor EPR method. The value k1 = (1.5±0.2) × 10 -12 cm 3 molecule -1 s -1 was obtained. Previous indirect measurements of k1 from a discharge-flow, LIF/mass spectrometric study of the Br/H 2CO/O 2 system have been reinterpreted, leading to values for k1 ranging from 1.0 × 10 -12 to 2.2 × 10 -12 cm 3 molecule -1 s -1 at 298 K. These results are discussed and compared with other literature values.

  1. Determination of the absolute chirality of tellurium using resonant diffraction with circularly polarized x-rays.

    PubMed

    Tanaka, Y; Collins, S P; Lovesey, S W; Matsumami, M; Moriwaki, T; Shin, S

    2010-03-31

    Many proteins, sugars and pharmaceuticals crystallize into two forms that are mirror images of each other (enantiomers) like our right and left hands. Tellurium is one enantiomer having a space group pair, P3(1)21 (right-handed screw) and P3(2)21 (left-handed screw). X-ray diffraction with dispersion correction terms has been playing an important role in determining the handedness of enantiomers for a long time. However, this approach is not applicable for an elemental crystal such as tellurium or selenium. We have demonstrated that positive and negative circularly polarized x-rays at the resonant energy of tellurium can be used to absolutely distinguish right from left tellurium. This method is applicable to chiral motifs that occur in biomolecules, liquid crystals, ferroelectrics and antiferroelectrics, multiferroics, etc.

  2. 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.

  3. 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.

  4. Determination of the absolute configurations at stereogenic centers in the presence of axial chirality.

    PubMed

    Polavarapu, Prasad L; Jeirath, Neha; Kurtán, Tibor; Pescitelli, Gennaro; Krohn, Karsten

    2009-01-01

    Cephalochromin, a homodimeric naphthpyranone natural product, contains both axial chirality due to the hindered rotation along the biaryl axis and central chirality due to the C-2, C-2' stereogenic centers of the fused pyranone ring. For determining the absolute configurations (ACs) of central chirality elements, different chiroptical spectroscopic methods, namely vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotation (OR), have been used. From these experimental data, in conjunction with corresponding quantum chemical predictions at B3LYP/6-311G* level, it is found that the ECD spectra of cephalochromin are dominated by its axial chirality and are not suitable to distinguish the (aS,2S,2'S) and (aS,2R,2'R) diastereomers and hence to determine the ACs of the central chirality elements. OR signs also did not distinguish the (aS,2S,2'S) and (aS,2R,2'R) diastereomers. On other hand, VCD spectrum of cephalochromin exhibited separate spectral features attributable to axial chirality and stereogenic centers, thereby allowing the determination of both types of chirality elements. This is the first investigation demonstrating that, because of vibrations specific to the studied stereogenic centers, VCD spectroscopy can be used to simultaneously determine the ACs of axial and central chirality elements whenever other chiroptical methods (ECD and OR) fail to report on them.

  5. 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.

  6. 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.

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

    DOEpatents

    Gold, R.; McElroy, W.N.

    1984-02-22

    A non-destructive method for determination of neutron exposure and constituent concentrations in an object, such as a 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 concentrations at regions of interest within the object.

  8. 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.

  9. Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography-multiangle laser light scattering.

    PubMed

    Ye, Hongping

    2006-09-01

    The feasibility of size exclusion chromotography (SEC)-multiangle laser-light scattering as a technique to investigate aggregation and degradation of glycosylated and nonglycosylated proteins, and antibodies under various conditions such as addition of detergent, changes in pH, and variation of protein concentration and heat stress temperature was examined. Separation of proteins and their aggregates was performed using SEC-high-performance liquid chromatography. Detection of analytes was carried out with on-line UV, refractive index, and multiangle laser light-scattering detectors. Quantification and molecular weight determination were performed using commercial software. Aggregation and degradation were examined under various conditions and quantitative results are presented for bovine serum albumin, choriogonadotropin, glyceraldehyde-3-phosphate dehydrogenase, Herceptin, and ReoPro. This method can simultaneously determine both the quantities and the molecular weights of macromolecules from a single injection. The determination of molecular weight is absolute which avoids misleading results caused by molecular shape or interactions with the column matrix. This technique is valuable not only for assessing the extent of aggregation but also for effectively monitoring molecule degradation as evidenced by molecular weight reduction and change in monomer amount.

  10. An absolute dose determination of helical tomotherapy accelerator, TomoTherapy High-Art II

    SciTech Connect

    Bailat, Claude J.; Buchillier, Thierry; Pachoud, Marc; Moeckli, Raphaeel; Bochud, Francois O.

    2009-09-15

    Purpose: A helical tomotherapy accelerator presents a dosimetric challenge because, to this day, there is no internationally accepted protocol for the determination of the absolute dose. Because of this reality, we investigated the different alternatives for characterizing and measuring the absolute dose of such an accelerator. We tested several dosimetric techniques with various metrological traceabilities as well as using a number of phantoms in static and helical modes. Methods: Firstly, the relationship between the reading of ionization chambers and the absorbed dose is dependent on the beam quality value of the photon beam. For high energy photons, the beam quality is specified by the tissue phantom ratio (TPR{sub 20,10}) and it is therefore necessary to know the TPR{sub 20,10} to calculate the dose delivered by a given accelerator. This parameter is obtained through the ratio of the absorbed dose at 20 and 10 cm depths in water and was measured in the particular conditions of the tomotherapy accelerator. Afterward, measurements were performed using the ionization chamber (model A1SL) delivered as a reference instrument by the vendor. This chamber is traceable in absorbed dose to water in a Co-60 beam to a water calorimeter of the American metrology institute (NIST). Similarly, in Switzerland, each radiotherapy department is directly traceable to the Swiss metrology institute (METAS) in absorbed dose to water based on a water calorimeter. For our research, this traceability was obtained by using an ionization chamber traceable to METAS (model NE 2611A), which is the secondary standard of our institute. Furthermore, in order to have another fully independent measurement method, we determined the dose using alanine dosimeters provided by and traceable to the British metrology institute (NPL); they are calibrated in absorbed dose to water using a graphite calorimeter. And finally, we wanted to take into account the type of chamber routinely used in clinical

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

    PubMed

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

    2014-05-27

    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

  12. In vivo online magnetic resonance quantification of absolute metabolite concentrations in microdialysate

    PubMed Central

    Glöggler, Stefan; Rizzitelli, Silvia; Pinaud, Noël; Raffard, Gérard; Zhendre, Vanessa; Bouchaud, Véronique; Sanchez, Stéphane; Radecki, Guillaume; Ciobanu, Luisa; Wong, Alan; Crémillieux, Yannick

    2016-01-01

    In order to study metabolic processes in animal models of diseases and in patients, microdialysis probes have evolved as powerful tools that are minimally invasive. However, analyses of microdialysate, performed remotely, do not provide real-time monitoring of microdialysate composition. Microdialysate solutions can theoretically be analyzed online inside a preclicinal or clinical MRI scanner using MRS techniques. Due to low NMR sensitivity, acquisitions of real-time NMR spectra on very small solution volumes (μL) with low metabolite concentrations (mM range) represent a major issue. To address this challenge we introduce the approach of combining a microdialysis probe with a custom-built magnetic resonance microprobe that allows for online metabolic analysis (1H and 13C) with high sensitivity under continuous flow conditions. This system is mounted inside an MRI scanner and allows performing simultaneously MRI experiments and rapid MRS metabolic analysis of the microdialysate. The feasibility of this approach is demonstrated by analyzing extracellular brain cancer cells (glioma) in vitro and brain metabolites in an animal model in vivo. We expect that our approach is readily translatable into clinical settings and can be used for a better and precise understanding of diseases linked to metabolic dysfunction. PMID:27811972

  13. Absolute densities, masses, and radii of the WASP-47 system determined dynamically

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Díaz, R. F.; Bonfils, X.; Udry, S.

    2016-10-01

    We present a self-consistent modelling of the available light curve and radial velocity data of WASP-47 that takes into account the gravitational interactions between all known bodies in the system. The joint analysis of light curve and radial velocity data in a multi-planetary system allows deriving absolute densities, radii, and masses without the use of theoretical stellar models. For WASP-47 the precision is limited by the reduced dynamical information that is due to the short time span of the K2 light curve. We achieve a precision of around 22% for the radii of the star and the transiting planets, between 40% and 60% for their masses, and between 1.5% and 38% for their densities. All values agree with previously reported measurements. When theoretical stellar models are included, the system parameters are determined with a precision that exceeds that achieved by previous studies, thanks to the self-consistent modelling of light curve and radial velocity data.

  14. 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

  15. 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.

  16. The high-precision videometrics methods to determining absolute vertical benchmark

    NASA Astrophysics Data System (ADS)

    Liu, Jinbo; Zhu, Zhaokun

    2013-01-01

    The mobile measurement equipment plays an important role in engineering measurement tasks and its measuring device is fixed with the vehicle platform. Therefore, how to correct the measured error in time that caused by swayed platform is a basic problem. Videometrics has its inherent advantages in solving this problem. First of all, videometrics technology is non-contact measurement, which has no effect on the target's structural characteristics and motion characteristics. Secondly, videometrics technology has high precision especially for surface targets and linear targets in the field of view. Thirdly, videometrics technology has the advantages of automatic, real-time and dynamic. This paper is mainly for mobile theodolite.etc that works under the environment of absolute vertical benchmark and proposed two high-precision methods to determine vertical benchmark: Direct-Extracting, which is based on the intersection of plats under the help of two cameras; Benchmark-Transformation, which gets the vertical benchmark by reconstructing the level-plat. Two methods both have the precision of under 10 seconds by digital simulation and physical experiments. The methods proposed by this paper have significance both on the theory and application.

  17. Spectrophotometric and colorimetric determination of protein concentration.

    PubMed

    Simonian, Michael H; Smith, John A

    2006-11-01

    This unit describes spectrophotometric and colorimetric methods for measuring the concentration of a sample protein in solution. Absorbance measurement at 280 nm is used to calculate protein concentration by comparison with a standard curve or published absorptivity values for that protein. An alternate protocol uses absorbance at 205 nm to calculate the protein concentration. Both methods can be used to quantitate total protein in crude lysates and purified or partially purified protein. Use of a spectrofluorometer or a filter fluorometer to measure the intrinsic fluorescence emission of a sample solution is also described. The measurement is compared with the emissions from standard solutions to determine the concentration of purified protein. The Bradford colorimetric method, based upon binding of the dye Coomassie brilliant blue to an unknown protein, is also presented, as is the Lowry method, which measures colorimetric reaction of tyrosyl residues in an unknown.

  18. 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.

  19. Non-invasive determination of absolute lung resistivity in adults using electrical impedance tomography.

    PubMed

    Zhang, Jie; Patterson, Robert

    2010-08-01

    Lung resistivity is a physiological parameter that describes the electrical characteristics of the lungs. Lung composition changes due to changes in the lung tissues, fluid and air volume. Various diseases that can cause a change in lung composition may be monitored by measuring lung resistivity. Currently, there is no accepted non-invasive method to measure lung resistivity. In this study, we presented a method and framework to non-invasively determine lung resistivity using electrical impedance tomography (EIT). By comparing actual measurements from subjects with data from a 3D human thorax model, an EIT image can be reconstructed to show a resistivity difference between the model and the subject. By adjusting the lung resistivity in the model, the resistivity difference in the lung regions can be reduced to near zero. This resistivity value then is the estimation of the lung resistivity of the subject. Using the proposed method, the lung resistivities of four normal adult males (43 +/- 13 years, 78 +/- 10 kg) in the supine position at air volumes starting at functional residual capacity (FRC--end expiration) and increasing in 0.5 l steps to 1.5 l were studied. The averaged lung resistivity changes 12.59%, from 1406 Omega cm to 1583 Omega cm, following the inspiration of 1.5 l air from FRC. The coefficients of variation (CV) of precision for the four subjects are less than 10%. The experiment was repeated five times at each air volume on a subject to test the reproducibility. The CVs are less than 3%. The results show that it is feasible to determine absolute lung resistivity using an EIT-based method.

  20. 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…

  1. 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.

  2. Patterns and determinants of functional and absolute iron deficiency in patients undergoing cardiac rehabilitation following heart surgery.

    PubMed

    Tramarin, Roberto; Pistuddi, Valeria; Maresca, Luigi; Pavesi, Marco; Castelvecchio, Serenella; Menicanti, Lorenzo; de Vincentiis, Carlo; Ranucci, Marco

    2017-01-01

    Background Anaemia and iron deficiency are frequent following major surgery. The present study aims to identify the iron deficiency patterns in cardiac surgery patients at their admission to a cardiac rehabilitation programme, and to determine which perioperative risk factor(s) may be associated with functional and absolute iron deficiency. Design This was a retrospective study on prospectively collected data. Methods The patient population included 339 patients. Functional iron deficiency was defined in the presence of transferrin saturation <20% and serum ferritin ≥100 µg/l. Absolute iron deficiency was defined in the presence of serum ferritin values <100 µg/l. Results Functional iron deficiency was found in 62.9% of patients and absolute iron deficiency in 10% of the patients. At a multivariable analysis, absolute iron deficiency was significantly ( p = 0.001) associated with mechanical prosthesis mitral valve replacement (odds ratio 5.4, 95% confidence interval 1.9-15) and tissue valve aortic valve replacement (odds ratio 4.5, 95% confidence interval 1.9-11). In mitral valve surgery, mitral repair carried a significant ( p = 0.013) lower risk of absolute iron deficiency (4.4%) than mitral valve replacement with tissue valves (8.3%) or mechanical prostheses (22.5%). Postoperative outcome did not differ between patients with functional iron deficiency and patients without iron deficiency; patients with absolute iron deficiency had a significantly ( p = 0.017) longer postoperative hospital stay (median 11 days) than patients without iron deficiency (median nine days) or with functional iron deficiency (median eight days). Conclusions Absolute iron deficiency following cardiac surgery is more frequent in heart valve surgery and is associated with a prolonged hospital stay. Routine screening for iron deficiency at admission in the cardiac rehabilitation unit is suggested.

  3. 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.

  4. 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

    2016-02-18

    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.

  5. Determination of collagen fibril size via absolute measurements of second-harmonic generation signals.

    PubMed

    Bancelin, Stéphane; Aimé, Carole; Gusachenko, Ivan; Kowalczuk, Laura; Latour, Gaël; Coradin, Thibaud; Schanne-Klein, Marie-Claire

    2014-09-16

    The quantification of collagen fibril size is a major issue for the investigation of pathological disorders associated with structural defects of the extracellular matrix. Second-harmonic generation microscopy is a powerful technique to characterize the macromolecular organization of collagen in unstained biological tissues. Nevertheless, due to the complex coherent building of this nonlinear optical signal, it has never been used to measure fibril diameter so far. Here we report absolute measurements of second-harmonic signals from isolated fibrils down to 30 nm diameter, via implementation of correlative second-harmonic-electron microscopy. Moreover, using analytical and numerical calculations, we demonstrate that the high sensitivity of this technique originates from the parallel alignment of collagen triple helices within fibrils and the subsequent constructive interferences of second-harmonic radiations. Finally, we use these absolute measurements as a calibration for ex vivo quantification of fibril diameter in the Descemet's membrane of a diabetic rat cornea.

  6. Determination of collagen fibril size via absolute measurements of second-harmonic generation signals

    NASA Astrophysics Data System (ADS)

    Bancelin, Stéphane; Aimé, Carole; Gusachenko, Ivan; Kowalczuk, Laura; Latour, Gaël; Coradin, Thibaud; Schanne-Klein, Marie-Claire

    2014-09-01

    The quantification of collagen fibril size is a major issue for the investigation of pathological disorders associated with structural defects of the extracellular matrix. Second-harmonic generation microscopy is a powerful technique to characterize the macromolecular organization of collagen in unstained biological tissues. Nevertheless, due to the complex coherent building of this nonlinear optical signal, it has never been used to measure fibril diameter so far. Here we report absolute measurements of second-harmonic signals from isolated fibrils down to 30 nm diameter, via implementation of correlative second-harmonic-electron microscopy. Moreover, using analytical and numerical calculations, we demonstrate that the high sensitivity of this technique originates from the parallel alignment of collagen triple helices within fibrils and the subsequent constructive interferences of second-harmonic radiations. Finally, we use these absolute measurements as a calibration for ex vivo quantification of fibril diameter in the Descemet’s membrane of a diabetic rat cornea.

  7. Determination of the Absolute Configuration of Gliomasolide D through Total Syntheses of the C-17 Epimers.

    PubMed

    Seetharamsingh, B; Ganesh, Routholla; Reddy, D Srinivasa

    2017-02-24

    The absolute configuration at C-17, the carbon bearing the distal hydroxy group of the 14-membered natural product gliomasolide D, was assigned as R by comparison of (13)C NMR shifts and specific rotation values of the epimers at C-17. The first total synthesis of gliomasolide D along with its C-17 epimer, regioselective macrocyclization (18 membered vs 14 membered), and regioselective Wacker oxidation are highlights of the present work.

  8. Absolute thermal neutron fluence determination by thin film of natural uranium

    NASA Astrophysics Data System (ADS)

    Bigazzi, G.; Hadler N., J. C.; Iunes, P. J.; Oddone, M.; Paulo, S. R.; Zúñiga G., A.

    1995-01-01

    An absolute monitor of thermal neutron fluence based on the 235U induced fission was developed. This monitor is constituted by a solid state nuclear track detector juxtaposed to a natural uranium film with a negligible self-absorption to fission fragments. In order to perform the calibration of the films, the alpha-activity was measured by using nuclear emulsions. The preparation, calibration and employment procedures of this monitor are presented.

  9. Absolute age Determinations on Diamond by Radioisotopic Methods: NOT the way to Accurately Identify Diamond Provenance

    NASA Astrophysics Data System (ADS)

    Shirey, S. B.

    2002-05-01

    Gem-quality diamond contains such low abundances of parent-daughter radionuclides that dating the diamond lattice directly by isotopic measurements has been and will be impossible. Absolute ages on diamonds typically are obtained through measurements of their syngenetic mineral inclusions: Rb-Sr in garnet; Sm-Nd in garnet and pyroxene; Re-Os and U-Th-Pb in sulfide; K-Ar in pyroxene; and U-Pb in zircon. The application of the first two isotope schemes in the list requires putting together many inclusions from many diamonds whereas the latter isotope schemes permit ages on single diamonds. The key limitations on the application of these decay pairs are the availability and size of the inclusions, the abundance levels of the radionuclides, and instrumental sensitivity. Practical complications of radioisotope dating of inclusions are fatal to the application of the technique for diamond provenance. In all mines, the ratio of gem-quality diamonds to stones with datable inclusions is very high. Thus there is no way to date the valuable, marketable stones that are part of the conflict diamond problem, just their rare, flawed cousins. Each analysis destroys the diamond host plus the inclusion and can only be carried out in research labs by highly trained scientists. Thus, these methods can not be automated or applied to the bulk of diamond production. The geological problems with age dating are equally fatal to its application to diamond provenance. From the geological perspective, for age determination to work as a tool for diamond provenance studies, diamond ages would have to be specific to particular kimberlites or kimberlite fields and different between fields. The southern African Kaapvaal-Zimbabwe Craton and Limpopo Mobile Belt is the only cratonic region where age determinations have been applied on a large enough scale to a number of kimberlites to illustrate the geological problems in age measurements for diamond provenance. However, this southern African example

  10. 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.

  11. Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

    PubMed Central

    Thomas, Reji

    2016-01-01

    Summary Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine substitution (S-(−)-(E)-1). A reductive debromination of S-(−)-(E)-1 results in formation of one of the enantiomers of (E)-2. Using a combination of HPLC and CD spectroscopy we could safely assign the stereostructure of one of the enantiomers of (E)-2, the reduced product R-(−)-(E)-1. PMID:27829929

  12. Simultaneous oral therapeutic and intravenous 14C‐microdoses to determine the absolute oral bioavailability of saxagliptin and dapagliflozin

    PubMed Central

    Boulton, David W.; Kasichayanula, Sreeneeranj; Keung, Chi Fung (Anther); Arnold, Mark E.; Christopher, Lisa J.; Xu, Xiaohui (Sophia); LaCreta, Frank

    2013-01-01

    Aim To determine the absolute oral bioavailability (Fp.o.) of saxagliptin and dapagliflozin using simultaneous intravenous 14C‐microdose/therapeutic oral dosing (i.v.micro + oraltherap). Methods The Fp.o. values of saxagliptin and dapagliflozin were determined in healthy subjects (n = 7 and 8, respectively) following the concomitant administration of single i.v. micro doses with unlabelled oraltherap doses. Accelerator mass spectrometry and liquid chromatography‐tandem mass spectrometry were used to quantify the labelled and unlabelled drug, respectively. Results The geometric mean point estimates (90% confidence interval) Fp.o. values for saxagliptin and dapagliflozin were 50% (48, 53%) and 78% (73, 83%), respectively. The i.v.micro had similar pharmacokinetics to oraltherap. Conclusions Simultaneous i.v.micro + oraltherap dosing is a valuable tool to assess human absolute bioavailability. PMID:22823746

  13. 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

  14. 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.

  15. 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

  16. Absolute Configuration Determination by Quantum Mechanical Calculation of Chiroptical Spectra: Basics and Applications to Fungal Metabolites.

    PubMed

    Superchi, Stefano; Scafato, Patrizia; Górecki, Marcin; Pescitelli, Gennaro

    2017-03-10

    The application of quantum mechanical simulation of chiroptical properties, i.e. electronic circular dichroism (ECD), optical rotation (OR), and vibrational circular dichroism (VCD), to the assignment of the absolute configuration of chiral naturally occurring metabolites of fungal origin, is reviewed. The fundamentals of such chiroptical spectroscopies as well as the specific experimental and computational issues allied to the application of their ab initio calculation is reported. Some examples, related to the use of the ECD, VCD, and OR techniques and highlighting the practical application of the methods, are also described.

  17. 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

  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. Absolute infrared vibrational band intensities of molecular ions determined by direct laser absorption spectroscopy in fast ion beams

    SciTech Connect

    Keim, E.R.; Polak, M.L.; Owrutsky, J.C.; Coe, J.V.; Saykally, R.J. )

    1990-09-01

    The technique of direct laser absorption spectroscopy in fast ion beams has been employed for the determination of absolute integrated band intensities ({ital S}{sup 0}{sub {ital v}}) for the {nu}{sub 3} fundamental bands of H{sub 3}O{sup +} and NH{sup +}{sub 4}. In addition, the absolute band intensities for the {nu}{sub 1} fundamental bands of HN{sup +}{sub 2} and HCO{sup +} have been remeasured. The values obtained in units of cm{sup {minus}2} atm{sup {minus}1} at STP are 1880(290) and 580(90) for the {nu}{sub 1} fundamentals of HN{sup +}{sub 2} and HCO{sup +}, respectively; and 4000(800) and 1220(190) for the {nu}{sub 3} fundamentals of H{sub 3}O{sup +} and NH{sup +}{sub 4}, respectively. Comparisons with {ital ab} {ital initio} results are presented.

  20. Absolute measurements of the densities of silicon crystals in vacuum for a determination of the Avogadro constant

    SciTech Connect

    Fujii, K.; Tanaka, M.; Nezu, Y.

    1994-12-31

    Absolute measurements of the densities of 1-kg single-crystal silicon spheres have been performed for a determination of the Avogadro constant. A scanning type optical interferometer was used to measure the diameters of the spheres in vacuum, and the volumes were obtained by fitting the diameters to a series of spherical harmonics. Thickness of oxide layers on the surfaces of the spheres has been determined by using an ellipsometer to evaluate the effect on the density. Total uncertainties of the densities are estimated to be 0.1 ppm.

  1. Total Syntheses of (+)-Grandilodine C and (+)-Lapidilectine B and Determination of their Absolute Stereochemistry.

    PubMed

    Nakajima, Masaya; Arai, Shigeru; Nishida, Atsushi

    2016-03-01

    Enantioselective total syntheses of the Kopsia alkaloids (+)-grandilodine C and (+)-lapidilectine B were accomplished. A key intermediate, spirodiketone, was synthesized in 3 steps and converted into the chiral enone by enantioselective deprotonation followed by oxidation with up to 76 % ee. Lactone formation was achieved through stereoselective vinylation followed by allylation and ozonolysis. The total synthesis of (+)-grandilodine C was achieved by palladium-catalyzed intramolecular allylic amination and ring-closing metathesis to give 8- and 5-membered heterocycles, respectively. Selective reduction of a lactam carbonyl gave (+)-lapidilectine B. The absolute stereochemistry of both natural products was thereby confirmed. These syntheses enable the scalable preparation of the above alkaloids for biological studies.

  2. Absolute determination of the Na22(p,γ)Mg23 reaction rate in novae

    NASA Astrophysics Data System (ADS)

    Sallaska, A. L.; Wrede, C.; García, A.; Storm, D. W.; Brown, T. A. D.; Ruiz, C.; Snover, K. A.; Ottewell, D. F.; Buchmann, L.; Vockenhuber, C.; Hutcheon, D. A.; Caggiano, J. A.; José, J.

    2011-03-01

    Gamma-ray telescopes in orbit around the earth are searching for evidence of the elusive radionuclide Na22 produced in novae. Previously published uncertainties in the dominant destructive reaction, Na22(p,γ)Mg23, indicated new measurements in the proton energy range of 150 to 300 keV were needed to constrain predictions. We have measured the resonance strengths, energies, and branches directly and absolutely by using protons from the University of Washington accelerator with a specially designed beam line, which included beam rastering and cold vacuum protection of the Na22 implanted targets. The targets, fabricated at TRIUMF-ISAC, displayed minimal degradation over a ~20 C bombardment as a result of protective layers. We avoided the need to know the absolute stopping power, and hence the target composition, by extracting resonance strengths from excitation functions integrated over proton energy. Our measurements revealed that resonance strengths for Ep=213, 288, 454, and 610 keV are stronger by factors of 2.4-3.2 than previously reported. Upper limits have been placed on proposed resonances at 198, 209, and 232 keV. These substantially reduce the uncertainty in the reaction rate. We have re-evaluated the Na22(p,γ) reaction rate, and our measurements indicate the resonance at 213 keV makes the most significant contribution to Na22 destruction in novae. Hydrodynamic simulations including our rate indicate that the expected abundance of Na22 ejecta from a classical nova is reduced by factors between 1.5 and 2, depending on the mass of the white-dwarf star hosting the nova explosion.

  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.

  4. The 1H NMR method for the determination of the absolute configuration of 1,2,3-prim,sec,sec-triols.

    PubMed

    Lallana, Enrique; Freire, Félix; Seco, José Manuel; Quiñoa, Emilio; Riguera, Ricardo

    2006-09-28

    The absolute configuration of 1,2,3-prim,sec,sec-triols can be assigned by comparison of the 1H NMR spectra of the tris-(R)- and the tris-(S)-MPA ester derivatives. An experimental demonstration of this correlation with 24 triols of known absolute configuration and a protocol using two parameters-Deltadelta(RS)(H3) and the difference between Deltadelta RS (H2) and Deltadelta RS (H3) = absolute value (Delta(Deltadelta RS))-for its application to the determination of the absolute configuration of other triols are presented.

  5. 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.

  6. Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis

    SciTech Connect

    Yuan, H.S.H.; Stevens, R.C.; Bau, R. ); Mosher, H.S. ); Koetzle, T.F. )

    1994-12-20

    The absolute configuration of (+)-neopentyl-1-d alcohol, prepared by the reduction of 2,2-dimethylpropanol-1-d by actively fermenting yeast, has been determined to be S by neutron diffraction. The neutron study was carried out on the phthalate half ester of neopentyl-1-d alcohol, crystallized as its strychnine salt. The absolute configuration of the (-)-strychninium cation was first determined by an x-ray anomalous dispersion study of its iodide salt. The chiral skeleton of strychnine then served as a reference from which the absolute configuration of the -O-CHD-C(CH[sub 3])[sub 3] group of neopentyl phthalate was determined. Difference Fourier maps calculated from the neutron data showed unambiguously that the -O-CHD-C(CH[sub 3])[sub 3] groups of both independent molecules in the unit cell had the S configuration. This work proves conclusively that the yeast system reduces aldehydes by delivering hydrogen to the re face of the carbonyl group. Crystallographic details: (-)-strychninium (+)-neopentyl-1-d phthalate, space group P2[sub 1] (monoclinic), a = 18.564(6) [angstrom], b = 7.713(2) [angstrom], c = 23.361(8) [angstrom], [beta] = 94.18(4)[degrees], V = 3336.0(5) [angstrom][sup 3], Z = 2 (T = 100 K). Final agreement factors are R(F) = 0.073 for 2768 reflections collected at room temperature (x-ray analysis) and R(F) = 0.144 for 960 reflections collected at 100 K (neutron analysis). 49 refs., 7 figs., 2 tabs.

  7. Enantiomeric separation and determination of absolute stereochemistry of asymmetric molecules in drug discovery: building chiral technology toolboxes.

    PubMed

    McConnell, Oliver; Bach, Alvin; Balibar, Carl; Byrne, Neal; Cai, Yanxuan; Carter, Guy; Chlenov, Michael; Di, Li; Fan, Kristi; Goljer, Igor; He, Yanan; Herold, Don; Kagan, Michael; Kerns, Edward; Koehn, Frank; Kraml, Christina; Marathias, Vasilios; Marquez, Brian; McDonald, Leonard; Nogle, Lisa; Petucci, Christopher; Schlingmann, Gerhard; Tawa, Gregory; Tischler, Mark; Williamson, R Thomas; Sutherland, Alan; Watts, William; Young, Mairead; Zhang, Mei-Yi; Zhang, Yingru; Zhou, Dahui; Ho, Douglas

    2007-09-01

    The application of Chiral Technology, or the (extensive) use of techniques or tools for the determination of absolute stereochemistry and the enantiomeric or chiral separation of racemic small molecule potential lead compounds, has been critical to successfully discovering and developing chiral drugs in the pharmaceutical industry. This has been due to the rapid increase over the past 10-15 years in potential drug candidates containing one or more asymmetric centers. Based on the experiences of one pharmaceutical company, a summary of the establishment of a Chiral Technology toolbox, including the implementation of known tools as well as the design, development, and implementation of new Chiral Technology tools, is provided.

  8. Determination of the absolute configuration of the natural product Klaivanolide via density functional calculations of vibrational circular dichroism (VCD).

    PubMed

    Devlin, Frank J; Stephens, Philip J; Figadère, Bruno

    2009-01-01

    The absolute configuration (AC) of the antiprotozoal lactone, Klaivanolide, 1, from Uvaria klaineana, has been determined using Vibrational Circular Dichroism (VCD) spectroscopy. The experimental VCD spectrum of the (+) enantiomer of 1 was measured. To analyze the AC of (+)-1, the conformationally-averaged VCD spectrum of 7-S-1 was calculated using density functional theory (DFT) and the GAUSSIAN 03 program. The B3PW91/TZ2P conformationally-averaged VCD spectrum of 7-S-1 proves that the AC of 1 is 7-S-(+).

  9. 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.

  10. 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.

  11. SMN transcript levels in leukocytes of SMA patients determined by absolute real-time PCR

    PubMed Central

    Tiziano, Francesco Danilo; Pinto, Anna Maria; Fiori, Stefania; Lomastro, Rosa; Messina, Sonia; Bruno, Claudio; Pini, Antonella; Pane, Marika; D'Amico, Adele; Ghezzo, Alessandro; Bertini, Enrico; Mercuri, Eugenio; Neri, Giovanni; Brahe, Christina

    2010-01-01

    Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by homozygous mutations of the SMN1 gene. Three forms of SMA are recognized (type I–III) on the basis of clinical severity. All patients have at least one or more (usually 2–4) copies of a highly homologous gene (SMN2), which produces insufficient levels of functional SMN protein, because of alternative splicing of exon 7. Recently, evidence has been provided that SMN2 expression can be enhanced by pharmacological treatment. However, no reliable biomarkers are available to test the molecular efficacy of the treatments. At present, the only potential biomarker is the dosage of SMN products in peripheral blood. However, the demonstration that SMN full-length (SMN-fl) transcript levels are reduced in leukocytes of patients compared with controls remains elusive (except for type I). We have developed a novel assay based on absolute real-time PCR, which allows the quantification of SMN1-fl/SMN2-fl transcripts. For the first time, we have shown that SMN-fl levels are reduced in leukocytes of type II–III patients compared with controls. We also found that transcript levels are related to clinical severity as in type III patients SMN2-fl levels are significantly higher compared with type II and directly correlated with functional ability in type II patients and with age of onset in type III patients. Moreover, in haploidentical siblings with discordant phenotype, the less severely affected individuals showed significantly higher transcript levels. Our study shows that SMN2-fl dosage in leukocytes can be considered a reliable biomarker and can provide the rationale for SMN dosage in clinical trials. PMID:19603064

  12. 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

  13. 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.

  14. Determining the absolute configuration of (+)-mefloquine HCl, the side-effect-reducing enantiomer of the antimalaria drug Lariam.

    PubMed

    Schmidt, Manuel; Sun, Han; Rogne, Per; Scriba, Gerhard K E; Griesinger, Christian; Kuhn, Lars T; Reinscheid, Uwe M

    2012-02-15

    Even though the important antimalaria drug rac-erythro-mefloquine HCl has been on the market as Lariam for decades, the absolute configurations of its enantiomers have not been determined conclusively. This is needed, since the (-) enantiomer is believed to cause adverse side effects in malaria treatment resulting from binding to the adenosine receptor in the human brain. Since there are conflicting assignments based on enantioselective synthesis and anomalous X-ray diffraction, we determined the absolute configuration using a combination of NMR, optical rotatory dispersion (ORD), and circular dichroism (CD) spectroscopy together with density functional theory calculations. First, structural models of erythro-mefloquine HCl compatible with NMR-derived (3)J(HH) scalar couplings, (15)N chemical shifts, rotational Overhauser effects, and residual dipolar couplings were constructed. Second, we calculated ORD and CD spectra of the structural models and compared the calculated data with the experimental values. The experimental results for (-)-erythro-mefloquine HCl matched our calculated chiroptical data for the 11R,12S model. Accordingly, we conclude that the assignment of 11R,12S to (-)-erythro-mefloquine HCl is correct.

  15. Absolute Photometry

    NASA Astrophysics Data System (ADS)

    Hartig, George

    1990-12-01

    The absolute sensitivity of the FOS will be determined in SV by observing 2 stars at 3 epochs, first in 3 apertures (1.0", 0.5", and 0.3" circular) and then in 1 aperture (1.0" circular). In cycle 1, one star, BD+28D4211 will be observed in the 1.0" aperture to establish the stability of the sensitivity and flat field characteristics and improve the accuracy obtained in SV. This star will also be observed through the paired apertures since these are not calibrated in SV. The stars will be observed in most detector/grating combinations. The data will be averaged to form the inverse sensitivity functions required by RSDP.

  16. 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.

  17. Progress in absolute determination of {Phi}{sub 0} using superconducting magnetic levitation

    SciTech Connect

    Shiota, F.; Miki, Y.; Nuzu, Y.

    1994-12-31

    Superconducting magnetic levitation system for the determination of Magnetic Flux Quantum has been improved significantly in flux-up system using Josephson voltage. Studies are also in progress to improve mechanical measurement relevant to the floating body toward sub-ppm level uncertainty.

  18. Assays for determination of protein concentration.

    PubMed

    Olson, Bradley J S C; Markwell, John

    2007-05-01

    Biochemical analysis of proteins relies on accurate quantitation of protein concentration. This unit describes how to perform commonly used protein assays, e.g., Lowry, Bradford, BCA, and UV spectroscopic protein assays. The primary focus of the unit is assay selection, emphasizing sample and buffer compatibility. Protein assay standard curves and data processing fundamentals are discussed in detail. This unit also details high-throughput adaptations of the commonly used protein assays, and also contains a protocol for BCA assay of total protein in SDS-PAGE sample buffer that is used for equal loading of SDS-PAGE gels, which is reliable, inexpensive, and quick.

  19. Assays for determination of protein concentration.

    PubMed

    Olson, Bradley J S C; Markwell, John

    2007-09-01

    Biochemical analysis of proteins relies on accurate quantitation of protein concentration. This appendix describes how to perform commonly used protein assays, e.g., Lowry, Bradford, BCA, and UV spectroscopic protein assays. The primary focus of the appendix is assay selection, emphasizing sample and buffer compatibility. Protein assay standard curves and data processing fundamentals are discussed in detail. This appendix also details high-throughput adaptations of the commonly used protein assays, and also contains a protocol for BCA assay of total protein in SDS-PAGE sample buffer that is used for equal loading of SDS-PAGE gels, which is reliable, inexpensive, and quick.

  20. 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

  1. An absolute determination of the 14O ( β+) Fermi decay Q-value

    NASA Astrophysics Data System (ADS)

    White, R. E.; Naylor, H.; Barker, P. H.; Lovelock, D. M. J.; Smythe, R. M.

    1981-10-01

    The threshold energy for the reaction 14N(p, n) 14O has been determined to be 6353.02±0.08keV, yielding a corresponding energy release of 1808.25±0.10keV for the superallowed 14O decay. Using recent half-life values an ƒ Rt- value of 3084.4±1.1 s. is obtained for this decay.

  2. 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.

  3. The spatial relations between stimulus and response determine an absolute visuo-haptic calibration in pantomime-grasping.

    PubMed

    Davarpanah Jazi, Shirin; Heath, Matthew

    2017-03-24

    Pantomime-grasps entail a response to an area adjacent to (i.e., spatially dissociated pantomime-grasp), or previously occupied by (i.e., no-target pantomime-grasp) a target. Previous work has reported that pantomime-grasps differ kinematically from naturalistic grasps (i.e., grasping a physical target object) - a result taken to evince that pantomime-grasps are perception-based and mediated via relative visual information. However, such actions differ not only in terms of their visual properties, but also because the former precludes haptic feedback related to a target's absolute size. The current study provides four experiments examining whether experimenter-induced haptic feedback influences the information mediating spatially dissociated and no-target pantomime-grasps. Just-noticeable-difference scores were computed to determine whether grasps adhered to, or violated, the relative psychophysical properties of Weber's law. Spatially dissociated pantomime-grasps performed with haptic feedback adhered to Weber's law (Experiments 1-3), whereas their no-target pantomime-grasp counterparts violated the law (Experiment 4). Accordingly, we propose that the top-down demands of decoupling stimulus-response relations in spatially dissociated pantomime-grasping renders aperture shaping via a visual percept that is not directly influenced by the integration of haptic feedback. In turn, the decreased top-down demands of no-target pantomime-grasps allows haptic feedback to serve as a reliable sensory resource supporting an absolute visuo-haptic calibration.

  4. Spatially resolved absolute diffuse reflectance measurements for noninvasive determination of the optical scattering and absorption coefficients of biological tissue

    NASA Astrophysics Data System (ADS)

    Kienle, Alwin; Lilge, Lothar; Patterson, Michael S.; Hibst, Raimund; Steiner, Rudolf; Wilson, Brian C.

    1996-05-01

    The absorption and transport scattering coefficients of biological tissues determine the radial dependence of the diffuse reflectance that is due to a point source. A system is described for making remote measurements of spatially resolved absolute diffuse reflectance and hence noninvasive, noncontact estimates of the tissue optical properties. The system incorporated a laser source and a CCD camera. Deflection of the incident beam into the camera allowed characterization of the source for absolute reflectance measurements. It is shown that an often used solution of the diffusion equation cannot be applied for these measurements. Instead, a neural network, trained on the results of Monte Carlo simulations, was used to estimate the absorption and scattering coefficients from the reflectance data. Tests on tissue-simulating phantoms with transport scattering coefficients between 0.5 and 2.0 mm-1 and absorption coefficients between 0.002 and 0.1 mm -1 showed the rms errors of this technique to be 2.6% for the transport scattering coefficient and 14% for the absorption coefficients. The optical properties of bovine muscle, adipose, and liver tissue, as well as chicken muscle (breast), were also measured ex vivo at 633 and 751 nm. For muscle tissue it was found that the Monte Carlo simulation did not agree with experimental measurements of reflectance at distances less than 2 mm from the incident beam. Carlo, neural network.

  5. 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.

  6. 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.

  7. 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.

  8. Determination of protein concentration on substrates using fluorescence fluctuation microscopy

    NASA Astrophysics Data System (ADS)

    De Mets, Richard; Wang, Irène; Gallagher, Joseph; Destaing, Olivier; Balland, Martial; Delon, Antoine

    2014-03-01

    Micro-fabrication and surface functionalization imply to know the equilibrium surface concentration of various kinds of molecules. Paradoxically, this crucial parameter is often poorly controlled and even less quantified. We have used a technique belonging to the family of fluorescence fluctuation microscopy, namely Image Correlation Spectroscopy (ICS), to measure the absolute surface concentration of fibrinogen molecules adsorbed on glass substrates. As these molecules are immobile, the width of the autocorrelation of the confocal image obtained by scanning the sample only reflects that of the confocal Point Spread Function. Conversely, the amplitude of the autocorrelation is directly related to the average number of proteins simultaneously illuminated by the laser beam and therefore to their surface concentration. We have studied the surface concentration of fibrinogen proteins versus the initial concentration of these molecules, solubilized in the solution which has been deposited on the surface. The estimation of this relation can be biased for several reasons: the concentration of fibrinogen molecules in solution is difficult to control; the measurement of the surface concentration of adsorbed molecules can be strongly underestimated if the surface coverage or the molecular brightness is not uniform. We suggest methods to detect these artifacts and estimate the actual surface concentration, together with control parameters. Globally, fluorescence fluctuation microscopy is a powerful set of techniques when one wants to quantify the surface concentration of molecules at the micrometer scale.

  9. Using DNA origami nanostructures to determine absolute cross sections for UV photon-induced DNA strand breakage.

    PubMed

    Vogel, Stefanie; Rackwitz, Jenny; Schürman, Robin; Prinz, Julia; Milosavljević, Aleksandar R; Réfrégiers, Matthieu; Giuliani, Alexandre; Bald, Ilko

    2015-11-19

    We have characterized ultraviolet (UV) photon-induced DNA strand break processes by determination of absolute cross sections for photoabsorption and for sequence-specific DNA single strand breakage induced by photons in an energy range from 6.50 to 8.94 eV. These represent the lowest-energy photons able to induce DNA strand breaks. Oligonucleotide targets are immobilized on a UV transparent substrate in controlled quantities through attachment to DNA origami templates. Photon-induced dissociation of single DNA strands is visualized and quantified using atomic force microscopy. The obtained quantum yields for strand breakage vary between 0.06 and 0.5, indicating highly efficient DNA strand breakage by UV photons, which is clearly dependent on the photon energy. Above the ionization threshold strand breakage becomes clearly the dominant form of DNA radiation damage, which is then also dependent on the nucleotide sequence.

  10. Simultaneous Determination of Absolute Configuration and Quantity of Lipopeptides Using Chiral Liquid Chromatography/Mass Spectrometry and Diastereomeric Internal Standards.

    PubMed

    Nemati, Reza; Dietz, Christopher; Anstadt, Emily; Clark, Robert; Smith, Michael; Nichols, Frank; Yao, Xudong

    2017-02-28

    Lipopeptides promote innate immune response and are related to disease pathology. To investigate the newly emerging roles of lipopeptides, accurate measurements of stereoisomers with multiple chiral centers are essential yet challenging. This work uses (3R)- and (3S)-(15-methyl-3-((13-methyltetradecanoyl)oxy)hexadecanoyl)glycyl-l-serine, abbreviated as l-serine-(R+S)-Lipid 654, to develop a method that combines chiral liquid chromatography, a diastereomeric mixture of isotopically labeled internal standards, and multiple reaction monitoring mass spectrometry. The new method allows for simultaneously determining the absolute configuration and quantity of stereoisomers of bacteria-derived lipopeptides. Total lipid extracts of nine evaluated bacteria strains had different amounts, but only the (R)-isoform of l-serine-Lipid 654. The developed method also allowed for the first quantitative analysis of hydrolysis of a nonphospholipid as a novel substrate of honey bee venom phospholipase A2.

  11. The recent absolute total np and pp cross section determinations: quality of data description and prediction of experimental observables

    SciTech Connect

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

    2010-01-01

    The absolute total cross sections for np and pp scattering below 1000 MeV 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-3.3 data files, and the Nijmegen PWA. Systematic deviations from the ENDF/B-VII.0 and JENDL-3.3 evaluations are found to exist in the low-energy region. Comparison of the np evaluation with the result of most recent np total and differential cross section measurements will be discussed. Results of those measurements were not used in the evaluation database. A comparison was done to check a quality of evaluation and its capabilities to predict experimental observables. Excellent agreement was found between the new experimental data and our PWA predictions.

  12. 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

  13. 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

  14. Determining protein concentrations of the human ventricular proteome.

    PubMed

    Scholten, Arjen; Heck, Albert J R

    2013-01-01

    Proteomics is mostly used for measurements of relative differences in protein concentrations. Although such analyses are meaningful for comparing differences between two and more conditions, they do not directly provide details on the absolute protein concentrations within a system. Now, proteomics is heading more towards absolute quantitative strategies with results being expressed in copies/cell or ng/mg tissue. In the cardiac context, such quantitative information is crucial for (1) evaluating the feasibility of selecting a certain protein as potential novel drug target, (2) the expected concentration excreted into the circulation when selecting a biomarker, and (3) to build a model of cardiac function at the molecular level. At the same time, by mass spectrometry-based proteomics, a wealth of spectral information is gathered that can be used to evaluate protein levels of a select set of novel disease-altered proteins using, for instance, single reaction monitoring. Here we describe how to build a quantitative map of the human left ventricular proteome using a simple yet effective mass spectrometry-based spectral count method.

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

    PubMed

    Hallacoglu, Bertan; Sassaroli, Angelo; Wysocki, Michael; Guerrero-Berroa, Elizabeth; Schnaider Beeri, Michal; Haroutunian, Vahram; Shaul, Merav; Rosenberg, Irwin H; Troen, Aron M; Fantini, Sergio

    2012-08-01

    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 available multi-distance frequency-domain system and analyzed using a diffusion theory model for a semi-infinite, homogeneous medium with semi-infinite boundary conditions. Our study included repeat measurements, taken five months apart, on 16 elderly volunteers that demonstrate intra-subject reproducibility of the absolute measurements with cross-correlation coefficients of 0.9 for absorption coefficient (μa), oxy-hemoglobin concentration ([HbO2]), and total hemoglobin concentration ([HbT]), 0.7 for deoxy-hemoglobin concentration ([Hb]), 0.8 for hemoglobin oxygen saturation (StO2), and 0.7 for reduced scattering coefficient (μ's). We found significant differences between the two age groups. Compared to young subjects, elderly subjects had lower cerebral [HbO2], [Hb], [HbT], and StO2 by 10 ± 4 μM, 4 ± 3 μM, 14 ± 5 μM, and 6%±5%, respectively. Our results demonstrate the reliability and robustness of multi-distance near-infrared spectroscopy measurements based on a homogeneous model in the human forehead on a large sample of human subjects. Absolute, non-invasive optical measurements on the brain, such as those presented here, can significantly advance the development of NIRS technology as a tool for monitoring resting/basal cerebral perfusion, hemodynamics, oxygenation, and metabolism.

  16. 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.

  17. Absolute parameter determination in low-mass eclipsing binaries - Radiative parameters for BH Vir, ZZ UMA and CR CAS

    NASA Astrophysics Data System (ADS)

    Clement, R.; Reglero, V.; Garcia, M.; Fabregat, J.; Bravo, A.; Suso, J.

    1993-01-01

    A new uvby and H-beta monitoring program of low mass eclipsing binaries is currently being carried out in the framework of a 5-yr observational program which also involves radial velocity determinations. The scope of this work is to provide very accurate absolute astrophysical parameters: mass, radius, and effective temperatures, for main-sequence late-type stars. One of the main goals is to improve the mass-luminosity relation in the low and intermediate mass range. A second objective is to perform accurate tests of the most recent grids of evolutionary models. This program is complementary to that currently being implemented by the Copenhagen group. In this contribution we present the photometric preliminary results obtained for three of the systems included in our long-term survey: BH Vir, ZZ UMa, and CR Cas for which primary eclipses have been observed. Particular attention is paid to the determination of reddening, distances, and radiative properties. A more detailed study will be carried out when the light curves and radial velocity measurements are completed.

  18. A vibrational circular dichroism approach to the determination of the absolute configurations of flavorous 5-substituted-2(5H)-furanones.

    PubMed

    Nakahashi, Atsufumi; Yaguchi, Yoshihiro; Miura, Nobuaki; Emura, Makoto; Monde, Kenji

    2011-04-25

    Sotolon (1) and maple furanone (2) are naturally occurring chiral furanones. These 5-substituted-2(5H)-furanones are industrially significant aroma compounds due to their characteristic organoleptic properties and extraordinarily low odor thresholds. Each enantiomer of 1 and 2 was successfully obtained by preparative enantioselective supercritical fluid chromatography. The absolute configuration of 1 was confirmed as (R)-(-)-1 and (S)-(+)-1 by adopting the vibrational circular dichroism (VCD) approach. The absolute configuration of 2, which has remained ambiguous since its discovery in 1957, was determined as (R)-(+)-2 and (S)-(-)-2 for the first time by the VCD technique. Surprisingly, the signs of the optical rotation of 2 are opposite of those of 1 regardless of their identical absolute configurations. This observation emphasizes the risk in absolute configurational assignments based on comparison of optical rotation signs of similar structures. Odor evaluation of the enantiomers of 2 revealed different odor intensities.

  19. Determination of Parameters of PV Concentrating System With Heliostat

    NASA Astrophysics Data System (ADS)

    Vardanyan, R.; Norsoyan, A.; Dallakyan, V.

    2010-10-01

    The structure of PV concentrating system with heliostat is analyzed. The mathematical model of system consisting of PV concentrating module and heliostat is developed. With the use of developed mathematical model the optimal parameters of the system are determined. The results of this work can be used during the design of PV concentrating systems with heliostats.

  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. SU-E-T-804: Verification of the BJR-25 Method of KQ Determination for CyberKnife Absolute Dosimetry

    SciTech Connect

    Gersh, J; Willett, B

    2015-06-15

    Purpose: Absolute calibration of the CyberKnife is performed using a 6cm-diameter cone defined at 80cm SAD. Since kQ is defined using PDD values determined using 10×10 cm fields at 100cm SSD, the PDD must be corrected in order to correctly apply the quality conversion factor. The accepted method is based on equivalent field-size conversions of PDD values using BJR25. Using the new InCise MLC system, the CK is capable of generating a rectangular field equivalent to 10×10 cm square field. In this study, a comparison is made between kQ values determined using the traditional BJR25 method and the MLC method introduced herein. Methods: First, kQ(BJR) is determined: a PDD is acquired using a 6cm circular field at 100cm SSD, its field size converted to an equivalent square, and PDD converted to a 10×10cm field using the appropriate BJR25 table. Maintaining a consistent setup, the collimator is changed, and the MLC method is used. Finally, kQ is determined using PDDs acquired with a 9.71×10.31cm at 100cm SSD. This field is produced by setting the field to a size of 7.77×8.25cm (since it is defined at 80cm SAD). An exact 10×10cm field since field size is relegated to increments of its leaf width (0.25cm). This comparison is made using an Exradin A1SL, IBA CC08, IBA CC13, and an Exradin A19. For each detector and collimator type, the beam injector was adjusted to give 5 different beam qualities; representing a range of clinical systems. Results: Averaging across all beam qualities, kQ(MLC) differed from kQ(BJR) by less than 0.15%. The difference between the values increased with detector volume. Conclusion: For CK users with standard cone collimators, the BJR25 method has been verified. For CK users the MLC system, a technique is described to determine kQ. Primary author is the President/Owner of Spectrum Medical Physics, LLC, a company which maintains contracts with Siemens Healthcare and Standard Imaging, Inc.

  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. Assessment of new radioimmunoassay kit for determining urinary albumin at low concentrations: comparison with radial immunodiffusion.

    PubMed Central

    Watts, G F; Albano, J D; Bennett, J E; Morris, R W; Shaw, K M; Polak, A

    1986-01-01

    The assay characteristics of a new radioimmunoassay kit for determining urinary albumin at low concentrations were studied. The sensitivity for urinary albumin was 2 mg/l, the analytical range 2 to 40 mg/l, and interassay coefficient of variation less than 12%. In a method comparison study entailing diabetic urine samples covering an albumin concentration of 2 to 150 mg/l the kit compared adequately with radial immunodiffusion (mean difference between methods = 2 mg/l; residual standard deviation = 4.6 mg/l), absolute variation between methods increasing with the concentration. The kit required much less skill than radial immunodiffusion but its capital and running cost were higher. PMID:3097081

  4. 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.

  5. Automatic twin vessel recrystallizer. Effective purification of acetaminophen by successive automatic recrystallization and absolute determination of purity by DSC.

    PubMed

    Nara, Osamu

    2011-01-24

    I describe an interchangeable twin vessel (J, N) automatic glass recrystallizer that eliminates the time-consuming recovery and recycling of crystals for repeated recrystallization. The sample goes in the dissolution vessel J containing a magnetic stir-bar K; J is clamped to the upper joint H of recrystallizer body D. Empty crystallization vessel N is clamped to the lower joint M. Pure solvent is delivered to the dissolution vessel and the crystallization vessel via the head of the condenser A. Crystallization vessel is heated (P). The dissolution reservoir is stirred and heated by the solvent vapor (F). Continuous outflow of filtrate E out of J keeps N at a stable boiling temperature. This results in efficient dissolution, evaporation and separation of pure crystals Q. Pure solvent in the dissolution reservoir is recovered by suction. Empty dissolution and crystallization vessels are detached. Stirrer magnet is transferred to the crystallization vessel and the role of the vessels are then reversed. Evacuating mother liquor out of the upper twin vessel, the apparatus unit is ready for the next automatic recrystallization by refilling twin vessels with pure solvent. We show successive automatic recrystallization of acetaminophen from diethyl ether obtaining acetaminophen of higher melting temperatures than USP and JP reference standards by 8× automatic recrystallization, 96% yield at each stage. Also, I demonstrate a novel approach to the determination of absolute purity by combining the successive automatic recrystallization with differential scanning calorimetry (DSC) measurement requiring no reference standards. This involves the measurement of the criterial melting temperature T(0) corresponding to the 100% pure material and quantitative ΔT in DSC based on the van't Hoff law of melting point depression. The purity of six commercial acetaminophen samples and reference standards and an eight times recrystallized product evaluated were 98.8 mol%, 97.9 mol%, 99

  6. 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....

  7. Cooperative use of VCD and XRD for the determination of tetrahydrobenzoisoquinolines absolute configuration: a reliable proof of memory of chirality and retention of configuration in enediyne rearrangements.

    PubMed

    Mondal, Shovan; Naubron, Jean-Valère; Campolo, Damien; Giorgi, Michel; Bertrand, Michéle P; Nechab, Malek

    2013-12-01

    The absolute configurations (AC) of azaheterocylic compounds resulting from the cascade rearrangement of enediynes involving only light atoms were unambiguously assigned by the joint use of vibrational circular dichroism (VCD) and copper radiation single crystal X-ray diffraction (XRD). These AC determinations proved that the rearrangements of enediynes proceeded with memory of chirality and retention of configuration.

  8. 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.

  9. A novel setup for the determination of absolute cross sections for low-energy electron induced strand breaks in oligonucleotides - The effect of the radiosensitizer 5-fluorouracil*

    NASA Astrophysics Data System (ADS)

    Rackwitz, Jenny; Ranković, Miloš Lj.; Milosavljević, Aleksandar R.; Bald, Ilko

    2017-02-01

    Low-energy electrons (LEEs) play an important role in DNA radiation damage. Here we present a method to quantify LEE induced strand breakage in well-defined oligonucleotide single strands in terms of absolute cross sections. An LEE irradiation setup covering electron energies <500 eV is constructed and optimized to irradiate DNA origami triangles carrying well-defined oligonucleotide target strands. Measurements are presented for 10.0 and 5.5 eV for different oligonucleotide targets. The determination of absolute strand break cross sections is performed by atomic force microscopy analysis. An accurate fluence determination ensures small margins of error of the determined absolute single strand break cross sections σ SSB . In this way, the influence of sequence modification with the radiosensitive 5-Fluorouracil (5FU) is studied using an absolute and relative data analysis. We demonstrate an increase in the strand break yields of 5FU containing oligonucleotides by a factor of 1.5 to 1.6 compared with non-modified oligonucleotide sequences when irradiated with 10 eV electrons.

  10. Determination of the absolute configuration of (-)-(2R)-succinic-2-d acid by neutron diffraction study: Unambiguous proof of the absolute stereochemistry of the NAD/sup +//NADH interconversion

    SciTech Connect

    Yuan, H.S.H.; Stevens, R.C.; Fujita, S.; Watkins, M.I.; Koetzle, T.F.; Bau, R.

    1988-05-01

    The absolute configuration of the CHD group (D = deuterium) in (-)-(2R)-succinic-2-d acid, as prepared from (-)-(2S,3R)-malic-3-d acid, has been shown unambiguously to be R by the technique of single-crystal neutron diffraction. The optically active cation (+)-phenylethylammonium was used as the chiral reference. The structure of (C/sub 6/H/sub 5/CH/sub 3/CHNH/sub 3/)/sup +/(HOOCCH/sub 2/CHDCOOO)/sup -/ has been studied with x-ray diffraction at room temperature and neutron diffraction at room temperature and neutron diffraction at 100 K. Crystal data from the neutron diffraction analysis of the phenylethylammonium slat of the title compound at 100 K: space group P2/sub 1/; a = 8.407 /angstrom/, b = 8.300 /angstrom/, c = 8.614 /angstrom/, ..beta.. = 91.20/degrees/; unit cell volume = 600.9 /angstrom//sup 3/, Z = 2. The result confirms the stereochemistry of the malate/succinate transformation, as well as the NAD/sup +//NADH interconversion, and demonstrates the usefulness of the single-crystal neutron diffraction method for determining the absolute configuration of molecules having a chiral monodeuteriomethylene group.

  11. Determination of the Zinc Concentration in Human Fingernails Using Laser-Induced Breakdown Spectroscopy.

    PubMed

    Riberdy, Vlora A; Frederickson, Christopher J; Rehse, Steven J

    2017-04-01

    The absolute concentration of Zn in human fingernail clippings was determined ex vivo using 1064 nm laser-induced breakdown spectroscopy and confirmed by speciated isotope dilution mass spectrometry. A nail testing protocol that sampled across the nail (perpendicular to the direction of growth) was developed and validated by scanning electron microscopy energy-dispersive X-ray spectrometry. Using this protocol, a partial least squares (PLS) regression model predicted the Zn concentration in the fingernails of five people to within an average of 7 ppm. The variation in the Zn concentration with depth into the nail determined by laser-induced breakdown spectroscopy was studied and showed no systematic variation for up to 15 subsequent laser pulses in one location. The effects of nail hydration (dehydrated and over-hydrated) and nail surface roughness were investigated to explain an anomalously large scatter observed in the measurements. This scatter was attributed to the layered nature and fibrous structure of the fingernails, which resulted in non-uniform ablation as determined by scanning electron microscopy. This work demonstrates that a protocol consisting of low pulse energy (<10 mJ) 1064 nm laser pulses incident on human fingernail clippings in an Ar environment can produce quantifiable Zn emission in the laser-induced plasma and that the measured Zn intensity can be used to accurately predict the Zn concentration in human fingernails.

  12. Structural determination of molecular stereochemistry using VCD spectroscopy and a conformational code: absolute configuration and solution conformation of a chiral liquid pesticide, (R)-(+)-malathion.

    PubMed

    Izumi, Hiroshi; Ogata, Atsushi; Nafie, Laurence A; Dukor, Rina K

    2009-01-01

    The absolute configuration and solution conformation of (R)-(+)-malathion were determined by using vibrational circular dichroism spectroscopy and a fragment-conformational search with a recently published conformational code. The determination of molecular stereochemistry was carried out without a conformational search using molecular mechanics calculations. Density functional theory calculations of the fragments of (R)-malathion, ethyl propionate, (R)-ethyl 2-(methylthio)propanoate, (R)-diethyl 2-(methylthio)succinate, and O,O,S-trimethyl phosphorodithioate were carried out, and the principal conformational features of the fragments were profiled. This fragment-conformational search reduces the time needed for the selection of the predominant conformations for (R)-malathion and significantly improves the accuracy of the determination of absolute configuration.

  13. 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. .

  14. Accurate determination of the sedimentation flux of concentrated suspensions

    NASA Astrophysics Data System (ADS)

    Martin, J.; Rakotomalala, N.; Salin, D.

    1995-10-01

    Flow rate jumps are used to generate propagating concentration variations in a counterflow stabilized suspension (a liquid fluidized bed). An acoustic technique is used to measure accurately the resulting concentration profiles through the bed. Depending on the experimental conditions, we have observed self-sharpening, or/and self-spreading concentration fronts. Our data are analyzed in the framework of Kynch's theory, providing an accurate determination of the sedimentation flux [CU(C); U(C) is the hindered sedimentation velocity of the suspension] and its derivatives in the concentration range 30%-60%. In the vicinity of the packing concentration, controlling the flow rate has allowed us to increase the maximum packing up to 60%.

  15. A Simple Synthesis of Alliin and allo-Alliin: X-ray Diffraction Analysis and Determination of Their Absolute Configurations.

    PubMed

    Hakamata, Wataru; Koyama, Ryosuke; Tanida, Mizuki; Haga, Tomomi; Hirano, Takako; Akao, Makoto; Kumagai, Hitomi; Nishio, Toshiyuki

    2015-12-23

    A simple method for the isolation of the bioactive compound alliin from garlic, as well as a method for the synthesis of diastereomerically pure alliin and allo-alliin on a preparative laboratory scale, was developed. The absolute configuration of the sulfur atom in alliin and allo-alliin was assigned on the basis of enzyme reactivity, optical rotatory dispersion, and circular dichroism analyses. A comparison of the results from these analyses, in combination with an X-ray diffraction study on a protected allo-alliin derivative, revealed S and R configurations of the sulfur atoms in alliin and allo-alliin, respectively. In addition, the same (1)H NMR spectrum was observed for synthetic and natural alliin. The absolute configuration of natural alliin was assigned for the first time on the basis of the NMR spectrum and X-ray coordinates.

  16. Determination of mantle upwelling rate beneath Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data

    NASA Astrophysics Data System (ADS)

    Xing, Lelin; Wang, Linhai; Hu, Minzhang

    2017-03-01

    The Taiyuan basin is in the Shanxi rift system of China. Results of tectonic studies indicate that the Moho is uplifted by 2-3 km under the Taiyuan basin. However, there is no quantitative evidence showing whether the rift is still in the status of mantle upwelling. Herein, we estimated mantle upwelling rate of Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data in this paper. In order to utilize the absolute gravity measurements in terms of tectonic study it is necessary to reduce all disturbing environmental effects. Many of those can be modeled, such as tide, polar motion, ocean tidal loading and atmospheric mass components. The Taiyuan station located in the Taiyuan basin, and absolute gravity measurements with a FG5 instrument were performed from 2009 to 2014, a secular trend was obtained. In-situ GPS data was used to estimate the vertical motion rate since 2011, and the result indicated a land subsidence. In-situ groundwater level was collected with daily surveys from 2009 to 2015, and local hydrology impact on effect was made. The global terrestrial water storage loading effect on gravity at Taiyuan station was computed by using GLDAS global hydrology model. Furthermore there is a good agreement between GRACE results and GLDAS hydrological model results. Subtracting the gravity change rate attributable to the land subsidence, groundwater level and global hydrology from the absolute gravity change rate, the residual gravity change rate was obtained. It reflects mantle upwelling about 2.1 ± 2.6 cm/yr beneath Taiyuan basin.

  17. 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

  18. Absolute bioavailability of evacetrapib in healthy subjects determined by simultaneous administration of oral evacetrapib and intravenous [(13) C8 ]-evacetrapib as a tracer.

    PubMed

    Cannady, Ellen A; Aburub, Aktham; Ward, Chris; Hinds, Chris; Czeskis, Boris; Ruterbories, Kenneth; Suico, Jeffrey G; Royalty, Jane; Ortega, Demetrio; Pack, Brian W; Begum, Syeda L; Annes, William F; Lin, Qun; Small, David S

    2016-05-30

    This open-label, single-period study in healthy subjects estimated evacetrapib absolute bioavailability following simultaneous administration of a 130-mg evacetrapib oral dose and 4-h intravenous (IV) infusion of 175 µg [(13) C8 ]-evacetrapib as a tracer. Plasma samples collected through 168 h were analyzed for evacetrapib and [(13) C8 ]-evacetrapib using high-performance liquid chromatography/tandem mass spectrometry. Pharmacokinetic parameter estimates following oral and IV doses, including area under the concentration-time curve (AUC) from zero to infinity (AUC[0-∞]) and to the last measureable concentration (AUC[0-tlast ]), were calculated. Bioavailability was calculated as the ratio of least-squares geometric mean of dose-normalized AUC (oral : IV) and corresponding 90% confidence interval (CI). Bioavailability of evacetrapib was 44.8% (90% CI: 42.2-47.6%) for AUC(0-∞) and 44.3% (90% CI: 41.8-46.9%) for AUC(0-tlast ). Evacetrapib was well tolerated with no reports of clinically significant safety assessment findings. This is among the first studies to estimate absolute bioavailability using simultaneous administration of an unlabeled oral dose with a (13) C-labeled IV microdose tracer at about 1/1000(th) the oral dose, with measurement in the pg/mL range. This approach is beneficial for poorly soluble drugs, does not require additional toxicology studies, does not change oral dose pharmacokinetics, and ultimately gives researchers another tool to evaluate absolute bioavailability.

  19. Absolute neutrino mass scale

    NASA Astrophysics Data System (ADS)

    Capelli, Silvia; Di Bari, Pasquale

    2013-04-01

    Neutrino oscillation experiments firmly established non-vanishing neutrino masses, a result that can be regarded as a strong motivation to extend the Standard Model. In spite of being the lightest massive particles, neutrinos likely represent an important bridge to new physics at very high energies and offer new opportunities to address some of the current cosmological puzzles, such as the matter-antimatter asymmetry of the Universe and Dark Matter. In this context, the determination of the absolute neutrino mass scale is a key issue within modern High Energy Physics. The talks in this parallel session well describe the current exciting experimental activity aiming to determining the absolute neutrino mass scale and offer an overview of a few models beyond the Standard Model that have been proposed in order to explain the neutrino masses giving a prediction for the absolute neutrino mass scale and solving the cosmological puzzles.

  20. 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.

  1. Determination of Flux Control Coefficients from transient metabolite concentrations.

    PubMed Central

    Delgado, J; Liao, J C

    1992-01-01

    Flux Control Coefficients have been used in the analysis of metabolic regulation for quantifying the effect of an enzyme on the overall steady-state flux. However, the experimental determination of these coefficients is very time-consuming, involving either determining the individual enzyme kinetics or perturbing the enzyme activity by genetic or other means. We developed a methodology that enables the determination of the Flux Control Coefficients from transient metabolite concentrations without knowing kinetic parameters. The transient states can be generated by changing the incubation conditions or adding the initial substrate. This approach is suitable for investigating metabolic regulation in vivo or multiple enzyme systems in vitro. It is particularly helpful if used in conjunction with n.m.r. measurements. The approach is based on a relationship between transient metabolite concentrations and the Flux Control Coefficients. The methodology has been improved from our previous results, and it is illustrated by three examples with simple pathway topologies. PMID:1554375

  2. Potentiometric perchlorate determination at nanomolar concentrations in vegetables.

    PubMed

    Leoterio, Dilmo M S; Paim, Ana Paula S; Belian, Mônica F; Galembeck, André; Lavorante, André F; Pinto, Edgar; Amorim, Célia G; Araújo, Alberto N; Montenegro, Maria C B S M

    2017-07-15

    In this work, an expeditious method based on the multi-commutated flow-analysis concept with potentiometric detection is proposed to perform determinations of the emergent contaminant perchlorate in vegetable matrices down to nanomolar concentration. To accomplish the task, a tubular shaped potentiometric sensor selective to perchlorate ion was constructed with a PVC membrane containing 12mmol/kg of the polyamine bisnaphthalimidopropyl-4,4'-diaminodiphenylmethane and 2-nitrophenyl phenyl ether 68% (w/w) as plasticizer casted on a conductive epoxy resin. Under optimal flow conditions, the sensor responded linearly in the concentration range of 6.3×10(-7)-1.0×10(-3)mol/L perchlorate. In order to extend the determinations to lower concentrations (4.6(±1.3)×10(-10)mol/L perchlorate), a column packed with 70mg of sodium 2,5,8,11,14-pentaoxa-1-silacyclotetradecane-polymer was coupled to the flow-system thus enabling prior pre-concentration of the perchlorate. The proposed procedure provides a simpler alternative for the determination of perchlorate in foods, nowadays only allowed by sophisticated and expensive equipment and laborious methods.

  3. Absolute quantification of the total and antidrug antibody-bound concentrations of recombinant human α-glucosidase in human plasma using protein G extraction and LC-MS/MS.

    PubMed

    Bronsema, Kees J; Bischoff, Rainer; Pijnappel, W W M Pim; van der Ploeg, Ans T; van de Merbel, Nico C

    2015-04-21

    The administration of protein-based pharmaceuticals can cause the in vivo formation of antidrug antibodies (ADAs), which may reduce the efficacy of the therapy by binding to the protein drug. An accurate determination of the total and ADA-bound concentrations of the drug gives information on the extent of this immune response and its consequences and may help develop improved therapeutic regimens. We present an absolute quantitative method to differentiate between total, free, and ADA-bound drug for recombinant human alpha acid glucosidase (rhGAA) in plasma from patients suffering from Pompe's disease. LC-MS/MS quantification of a signature peptide after trypsin digestion of plasma samples before and after an extraction of the total IgG content of plasma with protein G coated beads was used to determine the total and the ADA-bound fractions of rhGAA in samples from Pompe patients after enzyme infusion. The methods for total and ADA-bound rhGAA allow quantitation of the drug in the range of 0.5 to 500 μg/mL using 20 μL of plasma and met the regular bioanalytical validation requirements, both in the absence and presence of high levels of anti-rhGAA antibodies. This demonstrates that the ADA-bound rhGAA fraction can be accurately and precisely determined and is not influenced by sample dilution, repeated freezing and thawing, or extended benchtop or frozen storage. In samples from a patient with a reduced response to therapy due to ADAs, high ADA-bound concentrations of rhGAA were found, while in the samples from a patient lacking ADAs, no significant ADA-bound concentrations were found. Since protein G captures the complete IgG content of plasma, including all antidrug antibodies, the described extraction approach is universally applicable for the quantification of ADA-bound concentrations of all non-IgG-based biopharmaceuticals.

  4. Determination of minimum alveolar concentration of sevoflurane in juvenile swine.

    PubMed

    Moeser, Adam J; Blikslager, Anthony T; Swanson, Cliff

    2008-04-01

    Pigs are important animal models in veterinary and medical research and have been widely used in experiments requiring surgical anesthesia. Sevoflurane is an inhalant anesthetic with unique properties that make it an ideal anesthetic for mask induction and anesthesia maintenance. However, there are relatively few studies reporting the anesthetic requirements for sevoflurane in juvenile swine, an age group that is commonly used in research experiments. Therefore the objective of this study was to determine the Minimum Alveolar Concentration (MAC) for sevoflurane in juvenile swine. Sevoflurane anesthesia was induced in six Yorkshire-cross pigs of approximately 9 weeks-of-age and MAC for sevoflurane was determined. The sevoflurane MAC value was determined to be 3.5+/-0.1% which is notably higher than values reported in the literature for pigs. This discrepancy in MAC values may represent changes in anesthetic requirements between different age groups of pigs and differences in the type of stimulus used to determine MAC.

  5. 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.

  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.

  7. An electronic nose for quantitative determination of gas concentrations

    NASA Astrophysics Data System (ADS)

    Jasinski, Grzegorz; Kalinowski, Paweł; Woźniak, Łukasz

    2016-11-01

    The practical application of human nose for fragrance recognition is severely limited by the fact that our sense of smell is subjective and gets tired easily. Consequently, there is considerable need for an instrument that can be a substitution of the human sense of smell. Electronic nose devices from the mid 1980s are used in growing number of applications. They comprise an array of several electrochemical gas sensors with partial specificity and a pattern recognition algorithms. Most of such systems, however, is only used for qualitative measurements. In this article usage of such system in quantitative determination of gas concentration is demonstrated. Electronic nose consist of a sensor array with eight commercially available Taguchi type gas sensor. Performance of three different pattern recognition algorithms is compared, namely artificial neural network, partial least squares regression and support vector machine regression. The electronic nose is used for ammonia and nitrogen dioxide concentration determination.

  8. 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.

  9. 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.

  10. 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.

  11. Isolation of the major chiral compounds from Bubonium graveolens essential oil by HPLC and absolute configuration determination by VCD.

    PubMed

    Said, Mohammed El-Amin; Bombarda, Isabelle; Naubron, Jean-Valère; Vanloot, Pierre; Jean, Marion; Cheriti, Abdelkrim; Dupuy, Nathalie; Roussel, Christian

    2017-02-01

    The chirality issues in the essential oils (EOs) of leaves and flowers from Bubonium graveolens were addressed by chiral high-performance liquid chromatography (HPLC) with polarimetric detection and vibrational circular dichroism (VCD). The chemical compositions of the crude oils of three samples were established by gas chromatography / mass spectrometry (GC/MS). The well-known cis-chrysanthenyl acetate (1), oxocyclonerolidol (2), and the recently disclosed cis-acetyloxychrysanthenyl acetate (3), the three major chiral compounds, were isolated by preparative HPLC. The naturally occurring oxocycloneroledol (2), mostly found in the leaf oil (49.4-55.6%), presents a (+) sign in the mobile phase during HPLC on a chiral stationary phase (CSP) with a Jasco polarimetric detection. The naturally occurring cis-chrysanthenyl acetate (1) and cis-acetyloxychrysanthenyl acetate (3), mostly found in the flower EO (35.9-74.9% and 10.0-34.3%, respectively), both present a (-) sign. HPLC on a CSP with polarimetric detection is an unprecedented approach to readily differentiate the flower and leaf EOs according to their chiral signature. The comparison of the experimental and calculated VCD spectra of pure isolated 1, 2, and 3 provided their absolute configuration as being (1S,5R,6S)-(-)-2,7,7-trimethylbicyclo[3.1.1]hept-2-en-6-yl acetate 1, (2R,6R)-(+)-6-ethenyl-2,6-dimethyl-2-(4-methylpent-3-en-1-yl)dihydro-2H-pyran-3(4H)-one) 2 and (1S,5R,6R,7S)-(-)-7-(acetyloxy)-2,6-dimethylbicyclo[3.1.1]hept-2-en-6-yl]methyl acetate 3. Compounds 1, 2, and 3 were already known in B. graveolens but this is the first report of the absolute configuration of (+)-2 and (-)-3. The VCD chiral signatures of the crude oils were also recorded.

  12. Evaluation of nanoparticle-ligand distributions to determine nanoparticle concentration.

    PubMed

    Uddayasankar, Uvaraj; Shergill, Ravi T; Krull, Ulrich J

    2015-01-20

    The concentration of nanoparticles in solution is an important, yet challenging, parameter to quantify. In this work, a facile strategy for the determination of nanoparticle concentration is presented. The method relies on the quantitative analysis of the inherent distribution of nanoparticle-ligand conjugates that are generated when nanoparticles are functionalized with ligands. Validation of the method was accomplished by applying it to gold nanoparticles and semiconductor nanoparticles (CdSe/ZnS; core/shell). Poly(ethylene glycol) based ligands, with functional groups that quantitatively react with the nanoparticles, were incubated with the nanoparticles at varying equivalences. Agarose gel electrophoresis was subsequently used to separate and quantify the nanoparticle-ligand conjugates of varying valences. The distribution in the nanoparticle-ligand conjugates agreed well with that predicted by the Poisson model. A protocol was then developed, where a series of only eight different ligand amounts could provide an estimate of the nanoparticle concentration that spans 3 orders of magnitude (1 μM to 1 mM). For the gold nanoparticles and semiconductor nanoparticles, the measured concentrations were found to deviate by only 7% and 2%, respectively, from those determined by UV-vis spectroscopy. The precision of the assay was evaluated, resulting in a coefficient of variation of 5-7%. Finally, the protocol was used to determine the extinction coefficient of alloyed semiconductor nanoparticles (CdSxSe1-x/ZnS), for which a reliable estimate is currently unavailable, of three different emission wavelengths (525, 575, and 630 nm). The extinction coefficient of the nanoparticles of all emission wavelengths was similar and was found to be 2.1 × 10(5) M(-1)cm(-1).

  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. Determination of glucose concentration using Fourier domain optical coherence tomogram

    NASA Astrophysics Data System (ADS)

    El-Sharkawy, Yasser H.

    2009-02-01

    In order to enhance cell culture growth in biosensors such as those for glucose detection must be developed that are capable of monitoring cell culture processes continuously and accurate. Fourier domain optical coherence tomography (FD-OCT) is used to obtain cell images with nanometer level resolution by analyzing the interference pattern by the mixing of reference and objective light to determine glucose concentration in doped double distilled water and create a glucose signature spectrum in salt-sugar solution. We demonstrate ultrahigh-resolution optical coherence tomography (OCT) imaging of in vitro biological cells and an improved deflection angle measurements formal and back projection method is used to reconstruct the two-dimensional glucose concentration performs refractive index distribution. Slopes of OCT signals decreased substantially and almost linearly with the increase of glucose concentration from 2.5 to 15 mg/dl. Phantom studies demonstrated 1% accuracy of scattering- coefficient measurement. Our theoretical and experimental studies suggest that glucose concentration can potentially be measured non-invasively with high sensitivity and accuracy with OCT systems.

  15. Quantitative determination of infinite inhibition concentrations of antimicrobial agents.

    PubMed Central

    Marwan, A G; Nagel, C W

    1986-01-01

    We developed a method to determine the infinite inhibition concentrations (IICs) of antimicrobial agents. This method was based on finding the relative effectiveness of an inhibitor at various concentrations. Benzoic acid and parabens were tested on Saccharomyces bayanus, Hansenula sp., and Pseudomonas fluorescens. The relative effectiveness values of these compounds were established. A plot of the inhibitor concentration versus the reciprocal of relative effectiveness was linear. The chi-axis intercept was the concentration of the inhibitor which gave infinite microbial inhibition. For S. bayanus the IICs were 330, 930, 480, and 220 ppm (330, 930, 480, and 220 ml/liter) for benzoic acid and methyl-, ethyl-, and propylparabens, respectively. For Hansenula sp. the IIC was 180 ppm for benzoic acid. For P. fluorescens the IICs were 1,310, 960, and 670 ppm for methyl-, ethyl-, and propylparabens, respectively. Our results indicated that the IIC is affected by the growth medium. The advantages and applications of this method are discussed. PMID:3083773

  16. 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

  17. Simple enzymatic assay for determining cholesterol concentrations in bile.

    PubMed

    Luhman, C M; Galloway, S T; Beitz, D C

    1990-02-01

    We use bilirubin oxidase (EC 1.3.3.5) to remove interference by bilirubin in the assay of cholesterol concentration in bile by standard enzymatic methods. Samples are treated for 10 min with nonlimiting amounts of bilirubin oxidase to form biliverdin from bilirubin before the reagent for cholesterol is added. The relatively small interference by biliverdin is easily eliminated by use of sample blanks. The method is simple, convenient, and not hampered by the "chromogen oxidase" activity (the inherent ability of bilirubin oxidase to oxidize some chromogens) that plagues other assays of this type. Using this assay, we have accurately and precisely determined the concentration of cholesterol in bile. Such elimination of bilirubin will also be useful in assays of other biliary constituents or constituents of urine or icteric plasma.

  18. Comment on the Paper "Absolute Motion Determined from Michelson- Type Experiments in Optical Media" by V. P. Dmitriyev

    NASA Astrophysics Data System (ADS)

    Sfarti, Adrian

    2011-12-01

    Alternative explanations to the Michelson-Morley experiment exist and continue to be produced. In the current paper, we will correct a recently published paper concerning a reenactment of the famous experiment. The author of the paper in cause claims the presence of a non-null result though he did not run any experiment himself. Dmitriyev bases his paper on a paper by Demjanov that has already been retracted by the journal where he originally published (V. V. Demjanov, Phys. Lett. A 374, 1110 (2010)). Our paper is organized as follows: in the background section we will give the correct expressions for the relativistic light speed in arbitrary media as opposed to the incorrect ones given in V. P. Dmitriyev, Z. Naturforsch. 66a, 228 (2011). We will follow by explaining the correct equations of the Michelson-Morley experiment in a refractive medium with n > 1, and we will outline the errors in V. P. Dmitriyev, Z. Naturforsch. 66a, 228 (2011). The non-mainstream claims of detecting `absolute motion' are refuted by both theoretical and experimental data.

  19. Determination of beryllium concentrations in UK ambient air

    NASA Astrophysics Data System (ADS)

    Goddard, Sharon L.; Brown, Richard J. C.; Ghatora, Baljit K.

    2016-12-01

    Air quality monitoring of ambient air is essential to minimise the exposure of the general population to toxic substances such as heavy metals, and thus the health risks associated with them. In the UK, ambient air is already monitored under the UK Heavy Metals Monitoring Network for a number of heavy metals, including nickel (Ni), arsenic (As), cadmium (Cd) and lead (Pb) to ensure compliance with legislative limits. However, the UK Expert Panel on Air Quality Standards (EPAQS) has highlighted a need to limit concentrations of beryllium (Be) in air, which is not currently monitored, because of its toxicity. The aim of this work was to analyse airborne particulate matter (PM) sampled onto filter papers from the UK Heavy Metals Monitoring Network for quantitative, trace level beryllium determination and compare the results to the guideline concentration specified by EPAQS. Samples were prepared by microwave acid digestion in a matrix of 2% sulphuric acid and 14% nitric acid, verified by the use of Certified Reference Materials (CRMs). The digested samples were then analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The filters from the UK Heavy Metals Monitoring Network were tested using this procedure and the average beryllium concentration across the network for the duration of the study period was 7.87 pg m-3. The highest site average concentration was 32.0 pg m-3 at Scunthorpe Low Santon, which is significantly lower than levels that are thought to cause harm. However the highest levels were observed at sites monitoring industrial point sources, indicating that beryllium is being used and emitted, albeit at very low levels, from these point sources. Comparison with other metals concentrations and data from the UK National Atmospheric Emissions Inventory suggests that current emissions of beryllium may be significantly overestimated.

  20. Determination of atmospheric concentrations of xenon radioisotopes. Progress report

    SciTech Connect

    Abel, K.H.; Panisko, M.E.; Hensley, W.K.; Bowyer, T.W.; Perkins, R.W.

    1995-07-01

    Determination of radioactive xenon concentrations in the atmosphere over a two year period has been performed as part of a research program to develop real-time measurement capabilities. The initial measurements were made to develop, prove, and validate the authors technical approach, while the longer-term measurements are being undertaken to establish natural background concentrations and variability with time. The results reported were made using noble gas fraction (typically 90% Kr and 10% Xe by weight) gas samples obtained from a commercial air-reduction plant in the northeastern US over a two-year interval beginning in the fall of 1993. The concentrated gas samples were typically obtained during a 6--8 hour interval at the commercial reduction plant and were shipped overnight to their laboratory. Analysis was typically completed approximately 24 hours after sampling. The analytical separation process typically took approximately 6 hours and gamma-ray spectrometric measurements were conducted for intervals ranging from 3 to 16 hours. The technical approach involved removal of potentially interfering radon daughter radionuclides using a molecular sieve at room temperature, followed by cryogenic concentration of noble gases using a chilled ({minus}76 C) activated carbon molecular sieve. During initial measurements both molecular sieve materials were contained in 30 foot x 1/4 inch gas chromatography columns for analytical separations. Krypton was separated from Xenon during the analytical procedure by warming the activated carbon molecular sieve to room temperature after initial noble gas concentration and actively pumping it away. Xenon-133 adsorbed to the activated charcoal molecular sieve was then quantified via its 81 keV gamma-ray using initially a p-type intrinsic germanium detector and later a higher efficiency (64% relative to a 3 inch x 3 inch sodium iodide) n-type intrinsic germanium detector.

  1. 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.

  2. Electrophysiological Determination of Submembrane Na(+) Concentration in Cardiac Myocytes.

    PubMed

    Hegyi, Bence; Bányász, Tamás; Shannon, Thomas R; Chen-Izu, Ye; Izu, Leighton T

    2016-09-20

    In the heart, Na(+) is a key modulator of the action potential, Ca(2+) homeostasis, energetics, and contractility. Because Na(+) currents and cotransport fluxes depend on the Na(+) concentration in the submembrane region, it is necessary to accurately estimate the submembrane Na(+) concentration ([Na(+)]sm). Current methods using Na(+)-sensitive fluorescent indicators or Na(+) -sensitive electrodes cannot measure [Na(+)]sm. However, electrophysiology methods are ideal for measuring [Na(+)]sm. In this article, we develop patch-clamp protocols and experimental conditions to determine the upper bound of [Na(+)]sm at the peak of action potential and its lower bound at the resting state. During the cardiac cycle, the value of [Na(+)]sm is constrained within these bounds. We conducted experiments in rabbit ventricular myocytes at body temperature and found that 1) at a low pacing frequency of 0.5 Hz, the upper and lower bounds converge at 9 mM, constraining the [Na(+)]sm value to ∼9 mM; 2) at 2 Hz pacing frequency, [Na(+)]sm is bounded between 9 mM at resting state and 11.5 mM; and 3) the cells can maintain [Na(+)]sm to the above values, despite changes in the pipette Na(+) concentration, showing autoregulation of Na(+) in beating cardiomyocytes.

  3. Issues and progress in determining background ozone and particle concentrations

    NASA Astrophysics Data System (ADS)

    Pinto, J. P.

    2011-12-01

    Exposure to ambient ozone is associated with a variety of health outcomes ranging from mild breathing discomfort to mortality. For the purpose of health risk and policy assessments EPA evaluates the anthropogenic increase in ozone above background concentrations and has defined the North American (NA) background concentration of O3 as that which would occur in the U.S. in the absence of anthropogenic emissions of precursors in the U.S., Canada, and Mexico. Monthly average NA background ozone has been used to evaluate health risks, but EPA and state air quality managers must also estimate day specific ozone background levels for high ozone episodes as part of urban scale photochemical modeling efforts to support ozone regulatory programs. The background concentration of O3 is of more concern than other air pollutants because it typically represents a much larger fraction of observed O3 than do the backgrounds of other criteria pollutants (particulate matter (PM), CO, NO2, SO2). NA background cannot be determined directly from ambient monitoring data because of the influence of NA precursor emissions on formation of ozone within NA. Instead, estimates of NA background O3 have been based on GEOS-Chem using simulations in which NA anthropogenic precursor emissions are zeroed out. Thus, modeled NA background O3 includes contributions from natural sources of precursors (including CH4, NMVOCs, NOx, and CO) everywhere in the world, anthropogenic sources of precursors outside of NA, and downward transport of O3 from the stratosphere. Although monitoring data cannot determine NA background directly, measurements by satellites, aircraft, ozonesondes and surface monitors have proved to be highly useful for identifying sources of background O3 and for evaluating the performance of the GEOS-Chem model. Model simulated NA background concentrations are strong functions of location and season with large inter-day variability and with values increasing with elevation and higher in

  4. Metabolic control analysis using transient metabolite concentrations. Determination of metabolite concentration control coefficients.

    PubMed Central

    Delgado, J; Liao, J C

    1992-01-01

    The methodology previously developed for determining the Flux Control Coefficients [Delgado & Liao (1992) Biochem. J. 282, 919-927] is extended to the calculation of metabolite Concentration Control Coefficients. It is shown that the transient metabolite concentrations are related by a few algebraic equations, attributed to mass balance, stoichiometric constraints, quasi-equilibrium or quasi-steady states, and kinetic regulations. The coefficients in these relations can be estimated using linear regression, and can be used to calculate the Control Coefficients. The theoretical basis and two examples are discussed. Although the methodology is derived based on the linear approximation of enzyme kinetics, it yields reasonably good estimates of the Control Coefficients for systems with non-linear kinetics. PMID:1497632

  5. Absolute bioavailability of evacetrapib in healthy subjects determined by simultaneous administration of oral evacetrapib and intravenous [13C8]‐evacetrapib as a tracer

    PubMed Central

    Aburub, Aktham; Ward, Chris; Hinds, Chris; Czeskis, Boris; Ruterbories, Kenneth; Suico, Jeffrey G.; Royalty, Jane; Ortega, Demetrio; Pack, Brian W.; Begum, Syeda L.; Annes, William F.; Lin, Qun; Small, David S.

    2015-01-01

    This open‐label, single‐period study in healthy subjects estimated evacetrapib absolute bioavailability following simultaneous administration of a 130‐mg evacetrapib oral dose and 4‐h intravenous (IV) infusion of 175 µg [13C8]‐evacetrapib as a tracer. Plasma samples collected through 168 h were analyzed for evacetrapib and [13C8]‐evacetrapib using high‐performance liquid chromatography/tandem mass spectrometry. Pharmacokinetic parameter estimates following oral and IV doses, including area under the concentration‐time curve (AUC) from zero to infinity (AUC[0‐∞]) and to the last measureable concentration (AUC[0‐tlast]), were calculated. Bioavailability was calculated as the ratio of least‐squares geometric mean of dose‐normalized AUC (oral : IV) and corresponding 90% confidence interval (CI). Bioavailability of evacetrapib was 44.8% (90% CI: 42.2–47.6%) for AUC(0‐∞) and 44.3% (90% CI: 41.8–46.9%) for AUC(0‐tlast). Evacetrapib was well tolerated with no reports of clinically significant safety assessment findings. This is among the first studies to estimate absolute bioavailability using simultaneous administration of an unlabeled oral dose with a 13C‐labeled IV microdose tracer at about 1/1000th the oral dose, with measurement in the pg/mL range. This approach is beneficial for poorly soluble drugs, does not require additional toxicology studies, does not change oral dose pharmacokinetics, and ultimately gives researchers another tool to evaluate absolute bioavailability. PMID:26639670

  6. Determining Concentrations and Temperatures in Semiconductor Manufacturing Plasmas via Submillimeter Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Helal, Yaser H.; Neese, Christopher F.; De Lucia, Frank C.; Ewing, Paul R.; Agarwal, Ankur; Craver, Barry; Stout, Phillip J.; Armacost, Michael D.

    2016-06-01

    Plasmas used in the manufacturing processes of semiconductors are similar in pressure and temperature to plasmas used in studying the spectroscopy of astrophysical species. Likewise, the developed technology in submillimeter absorption spectroscopy can be used for the study of industrial plasmas and for monitoring manufacturing processes. An advantage of submillimeter absorption spectroscopy is that it can be used to determine absolute concentrations and temperatures of plasma species without the need for intrusive probes. A continuous wave, 500 - 750 GHz absorption spectrometer was developed for the purpose of being used as a remote sensor of gas and plasma species. An important part of this work was the optical design to match the geometry of existing plasma reactors in the manufacturing industry. A software fitting routine was developed to simultaneously fit for the background and absorption signal, solving for concentration, rotational temperature, and translational temperature. Examples of measurements made on inductively coupled plasmas will be demonstrated. We would like to thank the Texas Analog Center of Excellence/Semiconductor Research Corporation (TxACE/SRC) and Applied Materials for their support of this work.

  7. Determination of critical micelle concentration with the rotating sample system.

    PubMed

    Kao, Linus T; Shetty, Gautam N; Gratzl, Miklós

    2008-12-01

    A novel experimental approach using the rotating sample system (RSS) is proposed here for the determination of the critical micelle concentration (CMC) of surfactants. The RSS has been conceived in our laboratory as a convection platform for physicochemical studies and analyses in microliter-sized sample drops. The scheme allows for vigorous rotation of the drop despite its small size through efficient air-liquid mechanical coupling. Thus, changes in surface properties of aqueous samples result in corresponding modulation of the hydrodynamic performance of the RSS, which can be utilized to investigate interfacial phenomena. In this work, we demonstrate that the RSS can be used to study the effects of surfactants on the surface and in the bulk of very small samples with hydrodynamic electrochemistry. Potassium ferrocyanide is employed here with cyclic voltammetry to probe the air-water interface of solutions containing Triton X-100. The CMC of this surfactant determined using this approach is 140 ppm, which agrees well with reported values obtained with conventional methods in much larger samples. The results also demonstrate that besides the CMC, variations in bulk rheological properties can also be investigated in very small specimens using the RSS with a simple method.

  8. 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

  9. 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).

  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. 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.

  12. 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.

  13. Determination of kQ using MLC-collimated rectangular fields for absolute dosimetry of the CyberKnife.

    PubMed

    Gersh, Jacob A; Willett, Benjamin

    2015-11-01

    Traditional CyberKnife (CK) calibration uses TG-51, which requires kQ to be defined using the standard reference condition of 100 cm SSD in a 10 cm×10 cm field. Since the CK is calibrated using a 6 cm fixed-aperture collimating cone at 80 cm SAD, the BJR-25 method is commonly used to relate circular-field PDDs to square-field PDDs for kQ determination. Using the InCise MLC system, the CK is able to deliver rectangular fields, allowing a more direct measurement of %dd(10 cm) using conventional reference conditions. We define the PDD correction factor (CPDD) as the ratio of %dd(10 cm) measured using CK reference conditions to that measured using standard TG-51 reference conditions. Using four ionization chambers (A1SL, CC08, CC13, and A19), %dd(10 cm) is measured using a 6 cm fixed cone at 80 cm SSD and at 100 cm SSD using an effective 10 cm×10 cm MLC-collimated field. These values are used to calculate CPDD, while the latter is used to directly calculate a kQ value. This direct kQ value is then compared to values determined using the BJR-25 method. Using the MLC system, this study demonstrates conversion between the %dd(10 cm) measured using CyberKnife reference conditions and TG-51 reference conditions. These values provide the means for derivation of a kQ curve as a function of direct measurements of %dd(10 cm) using a 6 cm fixed-aperture collimating cone at 80 cm SSD. PACS number: 87.55.Qr.

  14. 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.

  15. 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…

  16. Absolute-structure reports.

    PubMed

    Flack, Howard D

    2013-08-01

    All the 139 noncentrosymmetric crystal structures published in Acta Crystallographica Section C between January 2011 and November 2012 inclusive have been used as the basis of a detailed study of the reporting of absolute structure. These structure determinations cover a wide range of space groups, chemical composition and resonant-scattering contribution. Defining A and D as the average and difference of the intensities of Friedel opposites, their level of fit has been examined using 2AD and selected-D plots. It was found, regardless of the expected resonant-scattering contribution to Friedel opposites, that the Friedel-difference intensities are often dominated by random uncertainty and systematic error. An analysis of data collection strategy is provided. It is found that crystal-structure determinations resulting in a Flack parameter close to 0.5 may not necessarily be from crystals twinned by inversion. Friedifstat is shown to be a robust estimator of the resonant-scattering contribution to Friedel opposites, very little affected by the particular space group of a structure nor by the occupation of special positions. There is considerable confusion in the text of papers presenting achiral noncentrosymmetric crystal structures. Recommendations are provided for the optimal way of treating noncentrosymmetric crystal structures for which the experimenter has no interest in determining the absolute structure.

  17. 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...

  18. Prospective determination of plasma imipenem concentrations in critically ill children.

    PubMed

    Giannoni, Eric; Moreillon, Philippe; Cotting, Jacques; Moessinger, Adrien; Bille, Jacques; Décosterd, Laurent; Zanetti, Giorgio; Majcherczyk, Paul; Bugnon, Denis

    2006-07-01

    Plasma imipenem concentrations were measured in 19 critically ill children (median age, 0.8 year; range, 0.02 to 12.9 years). Wide interindividual variations (2 to 4x at peak and >10x at trough concentrations) resulted in unpredictable plasma levels in several children. To avoid subtherapeutic drug levels, we recommend treatment with at least 100 mg/kg of body weight/day of imipenem-cilastatin for critically ill children requiring such therapy.

  19. Prospective Determination of Plasma Imipenem Concentrations in Critically Ill Children

    PubMed Central

    Giannoni, Eric; Moreillon, Philippe; Cotting, Jacques; Moessinger, Adrien; Bille, Jacques; Décosterd, Laurent; Zanetti, Giorgio; Majcherczyk, Paul; Bugnon, Denis

    2006-01-01

    Plasma imipenem concentrations were measured in 19 critically ill children (median age, 0.8 year; range, 0.02 to 12.9 years). Wide interindividual variations (2 to 4× at peak and >10× at trough concentrations) resulted in unpredictable plasma levels in several children. To avoid subtherapeutic drug levels, we recommend treatment with at least 100 mg/kg of body weight/day of imipenem-cilastatin for critically ill children requiring such therapy. PMID:16801447

  20. Determinants of nitrogen dioxide concentrations in indoor ice skating rinks.

    PubMed Central

    Levy, J I; Lee, K; Yanagisawa, Y; Hutchinson, P; Spengler, J D

    1998-01-01

    OBJECTIVES: The combination of poor ventilation and fuel-powered ice resurfacers has resulted in elevated nitrogen dioxide (NO2) concentrations in many indoor ice skating rinks. This study examined the factors influencing concentrations and the effects of various engineering controls in ice rinks with different resurfacer fuels. METHODS: Indoor NO2 concentrations were measured in 19 enclosed ice skating rinks over 3 winters by means of passive samplers, with 1-week average measurements during the first winter pilot study and single-day working-hour measurements in the final 2 winters. Personal exposures to drivers also were assessed during the last winter. RESULTS: Rinks in which propane-fueled resurfacers were used had a daily mean indoor NO2 concentration of 206 ppb, compared with 132 ppb for gasoline-fueled and 37 ppb for electric-powered resurfacers. Engineering controls, such as increased ventilation and resurfacer tuning, reduced NO2 concentrations by 65% on average, but outcomes varied widely, and concentrations increased in subsequent months. CONCLUSIONS: Electric ice resurfacers, increased ventilation, or emission control systems are recommended to protect the health of workers and patrons, with surveillance programs proposed to track implementation and maintain an observer effect. PMID:9842374

  1. 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.

  2. Determination of fluoride concentration in powdered milk in Iran 2010.

    PubMed

    Hossein Mahvi, Amir; Ghanbarian, Maryam; Ghanbarian, Marjan; Khosravi, Ahmad; Ghanbarian, Masoud

    2012-04-01

    High concentrations of fluoride (F) in powdered milk (formula milk) can have adverse health effects on the body. The F concentration in powdered milk was analysed in Iran in 2010. A total of twelve commercial brands of highly consumed powdered milk were selected to analyse the F content through the standard F ion-selective electrode method. From each brand, three samples with different production dates were selected. The means and standard deviation for F concentration in all the samples was 1·73 (sd 0·3) μg F/g. The minimum and maximum F content in powdered milk brands Humana2 and Humana3 was 1·32 (sd 0·1) and 2·36 (sd 0·3) μg F/g, respectively. The study revealed that there was no significant difference in F concentration in the samples that belonged to various dates. Humana3 had a high F concentration (with an average of 2·36 (sd 0·3) μg F/g), which can be a risk factor for increased dental fluorosis, especially when being prepared using water with a high content of F.

  3. Novel concept for the mass spectrometric determination of absolute isotopic abundances with improved measurement uncertainty: Part 1 - theoretical derivation and feasibility study

    NASA Astrophysics Data System (ADS)

    Rienitz, Olaf; Pramann, Axel; Schiel, Detlef

    2010-01-01

    The development of a new method for the experimental determination of absolute isotopic abundances using a modified isotope dilution mass spectrometry (IDMS) technique is described. The intention and thus main application will be the quantification of molar masses M of highly enriched materials with improved measurement uncertainty (Urel(M) [approximate] 10-8 with k = 2). In part 1 of the current work, the theoretical foundation of the new method and its mathematical derivation is shown in detail, while part 2 will cover the experiments based on the new method described. Its core idea is the introduction of a virtual element (VE) consisting of all isotopes but the one having the largest or smallest abundance. IDMS is used to determine the mass fraction of this VE in its matrix, namely the element itself. A new set of equations serve to calculate all isotopic abundances (even the large one omitted with the introduction of the VE) merely from the mass fraction of the VE. A comprehensive uncertainty budget according to the Guide to the Expression of Uncertainty in Measurement (GUM) was set up in order to discuss and validate the novel concept. The hypothetical input data of the uncertainty budget were estimated to resemble a silicon material highly enriched with respect to 28Si used in the context of the international Avogadro Project. Considering the calculated results, the experimental determination of the molar mass of the above mentioned silicon seems very promising. As far as the authors know, this will be the first time IDMS was applied to determine a molar mass.

  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. 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 ...

  6. 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 ...

  7. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Concentration for Group Determination... Table 1 to Subpart D of Part 65—Concentration for Group Determination Referencing subpart Concentration... of TOC. Subpart G of Part 63 50 ppmv of HAP 2. 1 The 50 ppm HAP concentration cutoff only applies...

  8. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Concentration for Group Determination... Table 1 to Subpart D of Part 65—Concentration for Group Determination Referencing subpart Concentration... of TOC. Subpart G of Part 63 50 ppmv of HAP 2. 1 The 50 ppm HAP concentration cutoff only applies...

  9. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Concentration for Group Determination... Table 1 to Subpart D of Part 65—Concentration for Group Determination Referencing subpart Concentration... of TOC. Subpart G of Part 63 50 ppmv of HAP 2. 1 The 50 ppm HAP concentration cutoff only applies...

  10. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Concentration for Group Determination... Table 1 to Subpart D of Part 65—Concentration for Group Determination Referencing subpart Concentration... of TOC. Subpart G of Part 63 50 ppmv of HAP 2. 1 The 50 ppm HAP concentration cutoff only applies...

  11. 40 CFR Table 1 to Subpart D of... - Concentration for Group Determination

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Concentration for Group Determination... Table 1 to Subpart D of Part 65—Concentration for Group Determination Referencing subpart Concentration... of TOC. Subpart G of Part 63 50 ppmv of HAP 2. 1 The 50 ppm HAP concentration cutoff only applies...

  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. Quantitative determination of urea concentrations in cell culture medium

    PubMed Central

    Zawada, Robert J.X.; Kwan, Peggy; Olszewski, Kellen L.; Llinas, Manuel; Huang, Shu-Gui

    2009-01-01

    Urea is the major nitrogenous end product of protein metabolism in mammals. Here, we describe a quantitative, sensitive method for urea determination using a modified Jung reagent. This assay is specific for urea and is unaffected by ammonia, a common interferent in tissue and cell cultures. We demonstrate that this convenient colorimetric microplate-based, room temperature assay can be applied to determine urea synthesis in cell culture. PMID:19448747

  14. Quantitative determination of urea concentrations in cell culture medium.

    PubMed

    Zawada, Robert J X; Kwan, Peggy; Olszewski, Kellen L; Llinas, Manuel; Huang, Shu-Gui

    2009-06-01

    Urea is the major nitrogenous end product of protein metabolism in mammals. Here, we describe a quantitative, sensitive method for urea determination using a modified Jung reagent. This assay is specific for urea and is unaffected by ammonia, a common interferent in tissue and cell cultures. We demonstrate that this convenient colorimetric microplate-based, room temperature assay can be applied to determine urea synthesis in cell culture.

  15. Simultaneous fluorometric determination of the concentrations of mixture components

    SciTech Connect

    Per'kov, I.G.; Drozd, A.V.; Podpruzhnikov, Yu.V.

    1987-11-20

    Utilizing the principle of the additivity of fluorescence, the simultaneous determination of isomers of naphthylamine in a mixture of these, zirconium and hafnium with morin, and of samarium and europium with thenoyltrifluoroacetate has been performed. Techniques are proposed for improving the agreement of the results of the simultaneous flurometric determination of the components of a mixture that are based on utilizing the different conditions for exciting fluorescence and the solvatochromic effect.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Absolutely classical spin states

    NASA Astrophysics Data System (ADS)

    Bohnet-Waldraff, F.; Giraud, O.; Braun, D.

    2017-01-01

    We introduce the concept of "absolutely classical" spin states, in analogy to absolutely separable states of bipartite quantum systems. Absolutely classical states are states that remain classical (i.e., a convex sum of projectors on coherent states of a spin j ) under any unitary transformation applied to them. We investigate the maximal size of the ball of absolutely classical states centered on the maximally mixed state and derive a lower bound for its radius as a function of the total spin quantum number. We also obtain a numerical estimate of this maximal radius and compare it to the case of absolutely separable states.

  1. Accurate determination of pyridine-poly(amidoamine) dendrimer absolute binding constants with the OPLS-AA force field and direct integration of radial distribution functions.

    PubMed

    Peng, Yong; Kaminski, George A

    2005-08-11

    OPLS-AA force field and direct integration of intermolecular radial distribution functions (RDF) were employed to calculate absolute binding constants of pyridine molecules to amino group (NH2) and amide group hydrogen atoms in and first generation poly(amidoamine) dendrimers in chloroform. The average errors in the absolute and relative association constants, as predicted with the calculations, are 14.1% and 10.8%, respectively, which translate into ca. 0.08 and 0.06 kcal/mol errors in the absolute and relative binding free energies. We believe that this level of accuracy proves the applicability of the OPLS-AA, force field, in combination with the direct RDF integration, to reproducing and predicting absolute intermolecular association constants of low magnitudes (ca. 0.2-2.0 range).

  2. Accurate Determination of Pyridine -- Poly (Amidoamine) Dendrimer Absolute Binding Constants with the OPLS-AA Force Field and Direct Integration of Radial Distribution Functions

    NASA Astrophysics Data System (ADS)

    Peng, Yong; Kaminski, George

    2006-03-01

    OPLS-AA force field and direct integration of intermolecular radial distribution functions (RDF) were employed to calculate absolute binding constants of pyridine molecules to NH2 and amide group hydrogen atoms in 0th and 1st generation poly (amidoamine) dendrimers in chloroform. The average errors in the absolute and relative association constants, as predicted with the calculations, are 14.1% and 10.8%, respectively, which translate into ca. 0.08 kcal/mol and 0.06 kcal/mol errors in the absolute and relative binding free energies. We believe that this level of accuracy proves the applicability of the OPLS-AA, force field, in combination with the direct RDF integration, to reproducing and predicting absolute intermolecular association constants of low magnitudes (ca. 0.2 -- 2.0 range).

  3. 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.

  4. Vibrational circular dichroism (VCD), VCD exciton coupling, and X-ray determination of the absolute configuration of an α,β-unsaturated germacranolide.

    PubMed

    Sánchez-Castellanos, Mariano; Bucio, María A; Hernández-Barragán, Angelina; Joseph-Nathan, Pedro; Cuevas, Gabriel; Quijano, Leovigildo

    2015-03-01

    The absolute configuration of was deduced by vibrational circular dichroism together with the evaluation of the Flack and Hooft X-ray parameters. Vibrational circular dichroism exciton coupling, using the carbonyl group signals, confirmed the absolute configuration of . In addition, sodium borohydride reduction of the 11,13-double bond of 6-epi-desacetyllaurenobiolide () yields an almost equimolecular mixture of C11 epimers, while reduction of the same double bond of 6-epi-laurenobiolide () provided almost exclusively the (11S) diastereoisomer .

  5. Determination of glucose concentrations using photonic crystal LEDs

    NASA Astrophysics Data System (ADS)

    Liao, Yu-Yang; Chen, Yung-Tsan; Chang, Cheng-Yu; Lan, Wen-Yi; Huang, Jian-Jang

    2016-09-01

    As internet of things (IOT) has become a popular topic in current consumer electronics, there is a demand for cost-effective sensors to monitor bio-signals. Traditional optical sensors employ low-dimensional gratings and high-resolution spectrometers to detect the refractive index changes of the solutions. In this work, we develop an alternative approach to correlate the concentration of molecules to the band diagrams of the photonic crystals. A relatively low-resolution spectrum analyzer can be employed, yet achieves higher sensitivity than traditional approaches.

  6. 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.

  7. Comparison of Methods to Determine Algal Concentrations in Freshwater Lakes

    NASA Astrophysics Data System (ADS)

    Georgian, S. E.; Halfman, J. D.

    2008-12-01

    Algal populations are extremely important to the ecological health of freshwater lake systems. As lakes become eutrophic (highly productive) through nutrient loading, sediment accumulation rates increase, bottom waters become anoxic in the mid-to late summer, the opacity of the water column decreases, and significantly decreases the lake's potential as a drinking water source and places respiratory stress on aquatic animals. One indicator of eutrophication is increasing algal concentrations over annual time frames. Algal concentrations can be measured by the concentration of chlorophyll a, or less directly by fluorescence, secchi disk depth, and turbidity by backscattering and total suspended solids. Here, we present a comparison of these methods using data collected on Honeoye, Canandaigua, Keuka, Seneca, Cayuga, Owasco, Skaneateles, and Otisco, the largest Finger Lakes of western and central New York State during the 2008 field season. A total of 124 samples were collected from at least two mid-lake, deep-water sites in each lake monthly through the 2008 field season (May-Oct); Seneca Lake was sampled weekly at four sites and Cayuga Lake every two weeks at six sites. Secchi depths, CTD profiles and surface water samples were collected at each site. Chlorophyll a was measured by spectrophotometer in the lab after filtration at 0.45 um and digestion of the residue in acetone. Water samples were also filtered through pre-weighed glass-fiber filters for total suspended solids concentrations. A SBE-25 SeaLogger CTD collected profiles of turbidity and fluorescence with WetLabs ECO FL-NTU. Surface CTD values were used in the comparison. The strongest linear correlations were detected between chlorophyll-a and fluorescence (r2 = 0.65), and total suspended solids and turbidity (r2 = 0.63). Weaker correlations were detected between secchi depths and chlorophyll-a (r2 = 0.42), and secchi depths and turbidity (r2 = 0.46). The weakest correlations were detected between secchi

  8. Hair sampling location in harbor seals (Phoca vitulina) affects selenium and mercury concentrations: implications for study design of trace element determination in pinnipeds.

    PubMed

    McHuron, Elizabeth A; Harvey, James T; Castellini, J Margaret; O'Hara, Todd M

    2012-11-01

    Hair is used to determine trace elements exposure and status of pinnipeds because it is an excretory route for many elements and can be collected non-lethally. Despite increased use, there have been few studies on how sampling designs and procedures (e.g., hair type, collection site) affect results. The objective of this study was to determine whether concentrations of an essential (selenium; Se) and non-essential element (mercury; Hg) differed between hair samples collected from two body locations on harbor seals (Phoca vitulina). Concentrations of Se and total Hg (THg) differed between mid-dorsal midline and neck samples, and although the absolute differences were relatively small (Δ(absolute) Se = 0.69 μg g(-1), Δ(absolute) THg = 2.86 μg g(-1)), the relative differences were large (Δ(relative) Se = 49%, Δ(relative) THg = 17%). These differences highlight the need to standardize the collection site for trace element determination in pinnipeds.

  9. Determination of water quality variables, endotoxin concentration, and enterobacteriaceae concentration and identification in Southern High Plains dairy lagoons

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 collecte...

  10. 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.

  11. Pattern-Based Recognition for the Rapid Determination of Identity, Concentration, and Enantiomeric Excess of Subtly Different Threo Diols

    PubMed Central

    Shabbir, Shagufta H.; Joyce, Leo A.; da Cruz, Gabriella M.; Lynch, Vincent M.; Sorey, Steven; Anslyn, Eric V.

    2009-01-01

    A pattern based recognition approach was developed for the rapid determination of identity, concentration, and enantiomeric excess of chiral vicinal diols, specifically threo diols. A diverse enantioselective sensor array was generated using three chiral boronic acid receptors and three pH indicators. The optical response produced by the sensor array was analyzed by two pattern recognition algorithms: principal component analysis and artificial neural networks. Principle component analysis demonstrated good chemoselective and enantioselective separation of the analytes, and an artificial neural network was used to accurately determine the concentration and enantiomeric excess of five unknown samples with an average absolute error of ± 0.08 mM in concentration and 3.6% in enantiomeric excess. The speed of the analysis was enhanced by using a 96-well plate format, which portents to applications in high-throughput screening for asymmetric catalyst discovery. X-ray crystallography and 11B NMR was utilized to study the enantioselective nature of boronic acid host-2. PMID:19691315

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    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.

  18. 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.

  19. 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

  20. Absolute Determination of Single-Stranded and Self-Complementary Adeno-Associated Viral Vector Genome Titers by Droplet Digital PCR

    PubMed Central

    Lock, Martin; Alvira, Mauricio R.; Chen, Shu-Jen

    2014-01-01

    Abstract 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

  1. Error analysis in newborn screening: can quotients support the absolute values?

    PubMed

    Arneth, Borros; Hintz, Martin

    2017-03-01

    Newborn screening is performed using modern tandem mass spectrometry, which can simultaneously detect a variety of analytes, including several amino acids and fatty acids. Tandem mass spectrometry measures the diagnostic parameters as absolute concentrations and produces fragments which are used as markers of specific substances. Several prominent quotients can also be derived, which are quotients of two absolute measured concentrations. In this study, we determined the precision of both the absolute concentrations and the derived quotients. First, the measurement error of the absolute concentrations and the measurement error of the ratios were practically determined. Then, the Gaussian theory of error calculation was used. Finally, these errors were compared with one another. The practical analytical accuracies of the quotients were significantly higher (e.g., coefficient of variation (CV) = 5.1% for the phenylalanine to tyrosine (Phe/Tyr) quotient and CV = 5.6% for the Fisher quotient) than the accuracies of the absolute measured concentrations (mean CVs = 12%). According to our results, the ratios are analytically correct and, from an analytical point of view, can support the absolute values in finding the correct diagnosis.

  2. A method for determining weights for excess relative risk and excess absolute risk when applied in the calculation of lifetime risk of cancer from radiation exposure.

    PubMed

    Walsh, Linda; Schneider, Uwe

    2013-03-01

    Radiation-related risks of cancer can be transported from one population to another population at risk, for the purpose of calculating lifetime risks from radiation exposure. Transfer via excess relative risks (ERR) or excess absolute risks (EAR) or a mixture of both (i.e., from the life span study (LSS) of Japanese atomic bomb survivors) has been done in the past based on qualitative weighting. Consequently, the values of the weights applied and the method of application of the weights (i.e., as additive or geometric weighted means) have varied both between reports produced at different times by the same regulatory body and also between reports produced at similar times by different regulatory bodies. Since the gender and age patterns are often markedly different between EAR and ERR models, it is useful to have an evidence-based method for determining the relative goodness of fit of such models to the data. This paper identifies a method, using Akaike model weights, which could aid expert judgment and be applied to help to achieve consistency of approach and quantitative evidence-based results in future health risk assessments. The results of applying this method to recent LSS cancer incidence models are that the relative EAR weighting by cancer solid cancer site, on a scale of 0-1, is zero for breast and colon, 0.02 for all solid, 0.03 for lung, 0.08 for liver, 0.15 for thyroid, 0.18 for bladder and 0.93 for stomach. The EAR weighting for female breast cancer increases from 0 to 0.3, if a generally observed change in the trend between female age-specific breast cancer incidence rates and attained age, associated with menopause, is accounted for in the EAR model. Application of this method to preferred models from a study of multi-model inference from many models fitted to the LSS leukemia mortality data, results in an EAR weighting of 0. From these results it can be seen that lifetime risk transfer is most highly weighted by EAR only for stomach cancer. However

  3. 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.

  4. Determination of the critical premicelle concentration, first critical micelle concentration and second critical micelle concentration of surfactants by resonance Rayleigh scattering method without any probe

    NASA Astrophysics Data System (ADS)

    Shi, Yan; Luo, Hong Qun; Li, Nian Bing

    2011-05-01

    The purpose of this work is to determine the values of critical premicelle concentration (CPMC), first critical micelle concentration (FCMC) and second critical micelle concentration (SCMC) of surfactants using a common spectrofluorophotometer by recording resonance Rayleigh scattering (RRS) signal without any probe. The plot of the RRS intensities at the maximum scattering wavelength ( IRRSmax) versus surfactant concentrations ( c) was constructed to obtain the IRRSmax-c curve. From the inflexions in IRRSmax-c curve, the CPMC, FCMC and SCMC values of a surfactant can be obtained sensitively. The FCMC of some anionic, cationic and nonionic surfactants such as sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), cetylpyridinium chloride (CPC), Tween-20, and Tween-80 were determined by RRS method and the values are in good agreement with those obtained from conductivity and surface tension measurements and literature values. The CPMC and SCMC of SDS and CTAB were also determined by RRS method respectively and the values conform to literature values too. Furthermore, RRS method can also be used to determine the FCMC of an amphiphilic macromolecule-hemoglobin, whose structure resembles a surfactant. From the experimental results, it is concluded that RRS method can be applied to the simultaneous determination of the CPMC, FCMC and SCMC values in a sensitive, accurate and no probe way.

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a....1426 Process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a PMPU. (a) Use of a flare. When a flare is used to comply...

  11. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a... Production § 63.1426 Process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a PMPU. (a) Use of a flare. When a flare is used...

  12. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a....1426 Process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a PMPU. (a) Use of a flare. When a flare is used to comply...

  13. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a....1426 Process vent requirements for determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a PMPU. (a) Use of a flare. When a flare is used to comply...

  14. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... determining organic HAP concentration, control efficiency, and aggregated organic HAP emission reduction for a... Production § 63.1426 Process vent requirements for determining organic HAP concentration, control efficiency... demonstrate the control efficiency for the flare, if the owner or operator chooses to assume a 98...

  15. Determination of glucose concentration in tissue-like material using spatially resolved steady-state diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Hjalmarsson, Pär; Thennadil, Suresh N.

    2008-02-01

    An important parameter in medical diagnostic and one of the most frequently determined analyte in the hospitals is blood glucose. Fast and accurate methods of measuring blood glucose concentrations could therefore be significant. We will in this paper investigate the feasibility of using a spatially resolved steady-state diffuse reflectance spectroscopy in the wavelength region 1000-1700nm, where glucose has two absorption peaks at around 1250nm and 1600nm, to quickly determine the concentration of glucose in tissue-like material. This method could later be transferred to estimate the amount of glucose in blood both in vivo e.g. the forearm and in vitro e.g. on blood samples. The novel spatially resolved system that is used for this study is based around a 2D InGaAs detector and a fibre probe with 10 fibres, one as a source and 9 to collect the diffuse reflected light at distances between 0.3-2.7mm from the source. An inversion method using Monte Carlo generated diffuse reflectance profiles is used to estimate the absolute absorption coefficient (μ a) and reduced scattering coefficient (μ s') which could be used to estimate the glucose concentration in the tissue-like phantoms. The method was investigated by performing spatially resolved measurements on turbid gelatin phantoms containing mixtures of water and D IIO as absorbers, Intralipid as a scatterer and glucose. The phantoms were made with four different glucose concentrations spanning the range of 0-5000 mg/dl.

  16. 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.

  17. Enantioseparation, absolute configuration determination, and anticonvulsant activity of (+/-)-1-(4-aminophenyl)-7,8-methylenedioxy-1,2,3,5-tetrahydro-4H-2,3-benzodiazepin-4-one.

    PubMed

    Calabrò, Maria Luisa; Raneri, Daniela; Ficarra, Paola; Ferreri, Guido; De Sarro, Giovambattista; Bruno, Giuseppe; Zappalà, Maria; Micale, Nicola; Grasso, Silvana

    2007-01-01

    The resolution of 1-(4-aminophenyl)-7,8-methylenedioxy-1,2,3,5-tetrahydro-4H-benzodiazepin-4-one (+/-)-(R,S)-2 was accomplished by chiral HPLC. The absolute configuration of (+)-2, determined by X-ray crystallographic analysis, was R. The in vivo anticonvulsant activity of the enantiomers (+)-(R)-2 and (-)-(S)-2 is reported. It has been also demonstrated that compound (+/-)-(R,S)-2 in vivo undergoes oxidative metabolism to derivative 1.

  18. 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.

  19. Estimating Absolute Site Effects

    SciTech Connect

    Malagnini, L; Mayeda, K M; Akinci, A; Bragato, P L

    2004-07-15

    The authors use previously determined direct-wave attenuation functions as well as stable, coda-derived source excitation spectra to isolate the absolute S-wave site effect for the horizontal and vertical components of weak ground motion. They used selected stations in the seismic network of the eastern Alps, and find the following: (1) all ''hard rock'' sites exhibited deamplification phenomena due to absorption at frequencies ranging between 0.5 and 12 Hz (the available bandwidth), on both the horizontal and vertical components; (2) ''hard rock'' site transfer functions showed large variability at high-frequency; (3) vertical-motion site transfer functions show strong frequency-dependence, and (4) H/V spectral ratios do not reproduce the characteristics of the true horizontal site transfer functions; (5) traditional, relative site terms obtained by using reference ''rock sites'' can be misleading in inferring the behaviors of true site transfer functions, since most rock sites have non-flat responses due to shallow heterogeneities resulting from varying degrees of weathering. They also use their stable source spectra to estimate total radiated seismic energy and compare against previous results. they find that the earthquakes in this region exhibit non-constant dynamic stress drop scaling which gives further support for a fundamental difference in rupture dynamics between small and large earthquakes. To correct the vertical and horizontal S-wave spectra for attenuation, they used detailed regional attenuation functions derived by Malagnini et al. (2002) who determined frequency-dependent geometrical spreading and Q for the region. These corrections account for the gross path effects (i.e., all distance-dependent effects), although the source and site effects are still present in the distance-corrected spectra. The main goal of this study is to isolate the absolute site effect (as a function of frequency) by removing the source spectrum (moment-rate spectrum) from

  20. High-Q ultrasonic determination of the critical nanoaggregate concentration of asphaltenes and the critical micelle concentration of standard surfactants.

    PubMed

    Andreatta, Gaëlle; Bostrom, Neil; Mullins, Oliver C

    2005-03-29

    Asphaltenes are known to be interfacially active in many circumstances such as at toluene-water interfaces. Furthermore, the term micelle has been used to describe the primary aggregation of asphaltenes in good solvents such as toluene. Nevertheless, there has been significant uncertainty regarding the critical micelle concentration (CMC) of asphaltenes and even whether the micelle concept is appropriate for asphaltenes. To avoid semantic debates we introduce the terminology critical nanoaggregate concentration (CNAC) for asphaltenes. In this report, we investigate asphaltenes and standard surfactants using high-Q, ultrasonic spectroscopy in both aqueous and organic solvents. As expected, standard surfactants are shown to exhibit a sharp break in sonic velocity versus concentration at known CMCs. To prove our methods, we measured known surfactants with CMCs in the range from 0.010 g/L to 2.3 g/L in agreement with the literature. Using density determinations, we obtain micelle compressibilities consistent with previous literature reports. Asphaltenes are also shown to exhibit behavior similar to that of ultrasonic velocity versus concentration as standard surfactants; asphaltene CNACs in toluene occur at roughly 0.1 g/L, although the exact concentration depends on the specific (crude oil) asphaltene. Furthermore, using asphaltene solution densities, we show that asphaltene nanoaggregate compressibilities are similar to micellar compressibilities obtained with standard nonionic surfactants in toluene. These results strongly support the contention that asphaltenes in toluene can be treated roughly within the micelle framework, although asphaltenes may exhibit small levels of aggregation (dimers, etc.) below their CNAC. Furthermore, our extensive results on known surfactants agree with the literature while the asphaltene CNACs reported here are one to two orders of magnitude lower than most previously published results. (Previous work utilized the terminology "micelle

  1. Absolute and relative blindsight.

    PubMed

    Balsdon, Tarryn; Azzopardi, Paul

    2015-03-01

    The concept of relative blindsight, referring to a difference in conscious awareness between conditions otherwise matched for performance, was introduced by Lau and Passingham (2006) as a way of identifying the neural correlates of consciousness (NCC) in fMRI experiments. By analogy, absolute blindsight refers to a difference between performance and awareness regardless of whether it is possible to match performance across conditions. Here, we address the question of whether relative and absolute blindsight in normal observers can be accounted for by response bias. In our replication of Lau and Passingham's experiment, the relative blindsight effect was abolished when performance was assessed by means of a bias-free 2AFC task or when the criterion for awareness was varied. Furthermore, there was no evidence of either relative or absolute blindsight when both performance and awareness were assessed with bias-free measures derived from confidence ratings using signal detection theory. This suggests that both relative and absolute blindsight in normal observers amount to no more than variations in response bias in the assessment of performance and awareness. Consideration of the properties of psychometric functions reveals a number of ways in which relative and absolute blindsight could arise trivially and elucidates a basis for the distinction between Type 1 and Type 2 blindsight.

  2. 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.

  3. 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.

  4. 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.

  5. Central-to-axial chirality transfer revealed by liquid crystals: a combined experimental and computational approach for the determination of absolute configuration of carboxylic acids with an α chirality centre.

    PubMed

    Ferrarini, Alberta; Ferroni, Fiammetta; Pieraccini, Silvia; Rosini, Carlo; Superchi, Stefano; Spada, Gian Piero

    2011-10-01

    The conversion into 6,7-dihydro-5H-dibenz[c,e]azepine (DAZ) N-protected amides is a viable route for the determination of the absolute configuration of chiral 2-substituted carboxylic acids. The biphenyl moiety of DAZ, besides being a probe of chirality for the electronic circular dichroism (ECD) spectroscopy, makes these systems suitable for configuration assignment by exploiting the chirality amplification which occurs in nematic liquid crystals. To assess the reliability of the liquid crystal method in detecting the absolute stereochemistry of chiral amides bound to a biphenyl group, we measured the helical twisting power of a series of DAZ-N-protected amides and compared these data with the results obtained from ECD measurements. We will show that the liquid crystal method, corroborated by HTP predictions, is trustworthy with our biphenyl derivatives, even when ECD spectra are ambiguous for the presence of aryl moieties displaying strong UV absorptions in the same range of the biphenyl chromophore.

  6. 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.

  7. 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.

  8. 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.

  9. Determination of ionic concentration in water using dry test reflectometric optical reader

    NASA Astrophysics Data System (ADS)

    Stanczak, Adam

    2003-11-01

    The application of a reflectometric method for determining ionic concentration in water using dry test is presented. The shape of reflectance spectum of dry tests changes in proportion to ionic concentration. A portable optical reader for acquisition of these spectra was developed to assure consistency and repeatability of measurements. A portable computer controls the process of measurement and calculates ionic concentration from the acquired spectrum.

  10. 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…

  11. 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...

  12. Optoacoustic Determination of Carbon Dioxide Concentration in Exhaled Breath in Various Human Diseases*

    NASA Astrophysics Data System (ADS)

    Ageev, V. G.; Nikiforova, O. Yu.

    2016-11-01

    We determined the carbon dioxide concentrations in exhaled breath from healthy donors and patients with various diseases from the absorption spectra of test samples, recorded on a laser optoacoustic gas analyzer based on a CO2 laser. We observed that the carbon dioxide concentrations in exhaled breath from healthy donors is higher than in patients with various diseases.

  13. 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 ...

  14. 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.

  15. [Determination of dissolution of liuwei dihuang concentrated pills based on multi-index components].

    PubMed

    Luo, Yun; Hao, Wei-Wei; Zhang, Jing; Liang, Xin-Li; Zhao, Guo-Wei; Yang, Ming; Liao, Zheng-Gen

    2014-01-01

    With the content of gallic acid, loganin, paeoniflorin and paeonol as the indexes, to screen out dissolution determination conditions, establish the dissolution determination method for multi-index components in Liuwei Dihuang concentrated pills, calculate and map the accumulative dissolution curve, and then compare the dissolution of products from different pharmaceutical factories through the similarity factor (f2). According to the results, the optimum dissolution determination conditions were the paddle method, with 250 mL 0.1 mol x L(-1) hydrochloric acid as the dissolution medium, and a rotation rate of 100 r x min(-1). The similarity factor values (f2) of the dissolution curves of the four main components of Liuwei Dihuang concentrated pills from different pharmaceutical factories were mostly less than 50. This demonstrated a significant difference in the dissolution of Liuwei Dihuang concentrated pills from different pharmaceutical factories, and provided scientific basis for improving the equality evaluation of Liuwei Dihuang concentrated pills.

  16. 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.

  17. [Determination of cyclohexanone concentration in the plasma separator by gas chromatography].

    PubMed

    Huang, Min-Ju; Yan, Lin; He, Yan-Ying; Lin, Wei-Cong

    2009-09-01

    This essay is to determine the cyclohexanone concentration of the plasma separator. The compound was introduced into the GC analytical system by the carrier gas. The determination was performed by the measurement of their peak area and by the external standard method.

  18. Using nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) for simultaneous determination of concentration and equilibrium constant.

    PubMed

    Kanoatov, Mirzo; Galievsky, Victor A; Krylova, Svetlana M; Cherney, Leonid T; Jankowski, Hanna K; Krylov, Sergey N

    2015-03-03

    Nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) is a versatile tool for studying affinity binding. Here we describe a NECEEM-based approach for simultaneous determination of both the equilibrium constant, K(d), and the unknown concentration of a binder that we call a target, T. In essence, NECEEM is used to measure the unbound equilibrium fraction, R, for the binder with a known concentration that we call a ligand, L. The first set of experiments is performed at varying concentrations of T, prepared by serial dilution of the stock solution, but at a constant concentration of L, which is as low as its reliable quantitation allows. The value of R is plotted as a function of the dilution coefficient, and dilution corresponding to R = 0.5 is determined. This dilution of T is used in the second set of experiments in which the concentration of T is fixed but the concentration of L is varied. The experimental dependence of R on the concentration of L is fitted with a function describing their theoretical dependence. Both K(d) and the concentration of T are used as fitting parameters, and their sought values are determined as the ones that generate the best fit. We have fully validated this approach in silico by using computer-simulated NECEEM electropherograms and then applied it to experimental determination of the unknown concentration of MutS protein and K(d) of its interactions with a DNA aptamer. The general approach described here is applicable not only to NECEEM but also to any other method that can determine a fraction of unbound molecules at equilibrium.

  19. Absolute quantitation of protein posttranslational modification isoform.

    PubMed

    Yang, Zhu; Li, Ning

    2015-01-01

    Mass spectrometry has been widely applied in characterization and quantification of proteins from complex biological samples. Because the numbers of absolute amounts of proteins are needed in construction of mathematical models for molecular systems of various biological phenotypes and phenomena, a number of quantitative proteomic methods have been adopted to measure absolute quantities of proteins using mass spectrometry. The liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with internal peptide standards, i.e., the stable isotope-coded peptide dilution series, which was originated from the field of analytical chemistry, becomes a widely applied method in absolute quantitative proteomics research. This approach provides more and more absolute protein quantitation results of high confidence. As quantitative study of posttranslational modification (PTM) that modulates the biological activity of proteins is crucial for biological science and each isoform may contribute a unique biological function, degradation, and/or subcellular location, the absolute quantitation of protein PTM isoforms has become more relevant to its biological significance. In order to obtain the absolute cellular amount of a PTM isoform of a protein accurately, impacts of protein fractionation, protein enrichment, and proteolytic digestion yield should be taken into consideration and those effects before differentially stable isotope-coded PTM peptide standards are spiked into sample peptides have to be corrected. Assisted with stable isotope-labeled peptide standards, the absolute quantitation of isoforms of posttranslationally modified protein (AQUIP) method takes all these factors into account and determines the absolute amount of a protein PTM isoform from the absolute amount of the protein of interest and the PTM occupancy at the site of the protein. The absolute amount of the protein of interest is inferred by quantifying both the absolute amounts of a few PTM

  20. The influence of walking with an orthosis on bone mineral density by determination of the absolute values of the loads applied on the limb.

    PubMed

    Karimi, Mohammad Taghi

    2012-03-01

    Spinal cord injury is damage to the spinal cord that results in loss of mobility and sensation below the level of injury. Most patients use various types of orthoses to stand and walk. It has been claimed that walking and standing with orthosis reduces bone osteoporosis, improves joint range of motion and decreases muscle spasm. Unfortunately, there are discrepancies regarding the clinical effects of walking and standing on bone mineral density. The aim of this research was to find the absolute values of the loads transmitted by body and orthosis in walking with use of an orthosis. 5 normal subjects were recruited to stand and walk with a new design of reciprocal gait orthosis. The loads transmitted through the orthosis and anatomy was measured by use of strain gauge and motion analysis systems. It has been shown that the loads applied on the anatomy were significantly more than that transmitted through the orthosis. Moreover, the patterns of the forces and moments of the orthosis and body completely differed from each other. As the most part of the loads applied on the complex transmitted by anatomy in walking with an orthosis, walking with orthosis can influence bone mineral density.

  1. 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.

  2. 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

    2005-04-21

    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$0\\atop{s}$ → D$-\\atop{s}$π+ signature is of paramount importance in the measurement of the Δms 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 Δms measurement; and measuring the B$0\\atop{d}$ mixing frequency in a B → Dπ 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-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.

  3. Watershed land use as a determinant of metal concentrations in freshwater systems.

    PubMed

    Das, Biplob; Nordin, Rick; Mazumder, Asit

    2009-12-01

    Concentrations of Fe, Mn, Cu, dissolved organic matter (DOM), and pH were synthesized from 30 publications to determine the factors regulating concentrations and behavior of metals in freshwater systems. Results from the review suggest that contrasting watershed land use can directly (erosion and runoff) and indirectly (in-lake processes including metal-DOM-pH interactions) affect the metal concentrations in freshwater systems. Among the watershed land uses considered here, concentrations of Fe, Mn, and Cu were observed in the following order: arctic lakes < forested < agricultural < urbanized < mined. A drastic difference in mean metal concentrations has been observed when undisturbed or low impact watersheds (arctic and forested) were changed by agricultural, urban, and mining developments. Relationships between metal concentrations and pH revealed that metals precipitate at high pH (pH > 5). Additionally, at pH < 5, metal concentrations were significantly correlated with DOM due to metal-DOM complexation. High ratios of metal: DOM occur only at low DOM concentrations. Collectively, two general conclusions can be drawn from this review. First, lakes, rivers, and streams with urbanized watersheds are the most susceptible to increased concentrations of metals. Secondly, these results also suggest that regardless of high or low DOM in the water column, pH would affect metal concentrations in freshwater systems. Nonetheless, free metal ions would be higher in freshwater systems with acidic water and low DOM.

  4. Determination of cellular RNA concentrations by electron microscopy of R loop-containing DNA.

    PubMed Central

    Kaback, D B; Rosbash, M; Davidson, N

    1981-01-01

    R loop hybridizations and electron microscopy have been used to determine cellular RNA concentrations for cloned genes. In plasmid DNA sequence excess, all the complementary RNA is driven into R loop structures that can be assayed by electron microscopy. To determine the concentration of a particular poly(A)+ RNA, plasmid DNA crosslinked once every 2000-5000 base pairs with trioxsalen and UV light is hybridized in DNA sequence excess to various known amounts of total poly(A)+ RNA, and the R loops are stabilized by treatment with glyoxal. If necessary, excess nonhybridized RNA is removed by Sepharose 2B chromatography, which enables the visualization of less abundant transcripts. Reconstruction experiments demonstrated that electron microscopic determination of the fraction of plasmid DNA molecules containing specific RNA loops gives accurate values of specific RNA weight fractions or concentrations in the total poly(A)+ RNA populations. These methods were also used to determine the concentrations of five RNA species complementary to sequences on TRT3, a recombinant DNA plasmid containing yeast histone 2A and 2B genes and three other nonhistone genes. The methods described allow one to visualize the R loop structures for both abundant and nonabundant transcripts and to estimate concentrations of these RNA species simply by determining the fraction of DNA containing R loops. Images PMID:6265914

  5. Absolute cross sections of compound nucleus reactions

    NASA Astrophysics Data System (ADS)

    Capurro, O. A.

    1993-11-01

    The program SEEF is a Fortran IV computer code for the extraction of absolute cross sections of compound nucleus reactions. When the evaporation residue is fed by its parents, only cumulative cross sections will be obtained from off-line gamma ray measurements. But, if one has the parent excitation function (experimental or calculated), this code will make it possible to determine absolute cross sections of any exit channel.

  6. 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.

  7. Determination of stress concentration coefficients upon cyclic loading by photometric analysis of structure images

    NASA Astrophysics Data System (ADS)

    Minina, N. A.; Emishkin, V. A.; Ovchinnikov, I. N.

    2017-01-01

    The development of an experimental method for the determination of stress concentration coefficient by the photometric analysis of surface reflectivity of material near stress concentrator and at a distance from it is considered in the paper. The experiments were performed with the AD-19 aluminum alloy samples under fatigue test conditions realized at a vibrating table with cantilevered sample. Notches 5 mm long and 0.4 mm wide spaced at constant intervals were applied by electrical discharge along one edge of the samples. The reflections of light from the fragments in the vicinity of the stress concentrator and from the opposite edge of the sample were compared with the help of photometric image analyzer. It is shown that such analysis can be used to determine the stress concentration coefficients.

  8. 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.

  9. Interaction of Exposure Concentration and Duration in Determining Acute Toxic Effects of Sarin Vapor in Rats

    DTIC Science & Technology

    2002-01-01

    effects occur in the rat and 2) develop models for predicting dose - response effects of low CW agent concentrations as a function of exposure duration. Sarin...effective concentrations for lethality (LC50) and miosis (EC50) in 50% of the exposed population and corresponding dose - response slopes were determined for...exposure duration (i.e., the CT for 50% lethality exposed population and corresponding dose - response slope was not constant over time). A plot of Log (LCt50

  10. 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.

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

    DOEpatents

    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.

  12. 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

  13. In vitro studies of Dermatophilus congolensis antimicrobial susceptibility by determining minimal inhibitory and bacteriocidal concentrations.

    PubMed

    Hermoso de Mendoza, J; Arenas, A; Rey, J; Alonso, J M; Gil, M C; Naranjo, G; Hermoso de Mendoza, M

    1994-01-01

    The Minimal Inhibitory Concentration (MIC) and Minimal Bacteriocidal Concentration (MBC) of 19 antimicrobials on 16 isolates of D. congolensis were determined. The potential field efficacy of the agents was evaluated by comparing the results with serum levels of drug unbound to proteins and the in vitro and in vivo findings of other authors. A modified standard microtechnique was used for serial dilution-antimicrobial sensitivity and found to be easy and reproducible. Erythromycin, spiramycin, penicillin G, ampicillin, chloramphenicol, the streptomycin, amoxicillin, the tetracyclines and novobiocin had high serum concentrations in comparison with their MBCs and were shown to have potential use for the treatment of dermatophilosis.

  14. Concentrations and determinants of gaseous aldehydes in 162 homes in Strasbourg (France)

    NASA Astrophysics Data System (ADS)

    Marchand, C.; Le Calvé, S.; Mirabel, Ph.; Glasser, N.; Casset, A.; Schneider, N.; de Blay, F.

    Aldehydes concentrations were measured in 162 homes in the Strasbourg area (East of France) in the context of a case/control study pairing asthmatic and non-asthmatic people. The surveyed people have completed a questionnaire aiming to characterize the indoor homes and the people life practices. Gaseous aldehyde levels were quantified by a conventional DNHP-derivatization method followed by HPLC/UV. Formaldehyde, acetaldehyde and hexanal were the main encountered aldehydes with mean concentrations of 32.2±14.6, 14.3±9.7 and 8.6±8.1 μg m -3, respectively, while propionaldehyde and benzaldehyde concentrations were usually <3 μg m -3. The aldehydes concentrations simultaneously measured in both bedroom and living room were not significantly different except for formaldehyde and were correlated between them meaning that indoor air was quite homogenous in homes. Combination of information collected in our questionnaires and statistical analysis was used to investigate indoor aldehydes determinants. Even if formaldehyde sources are theoretically well identified, they are multiple so that it was difficult to determine the main parameters influencing its concentrations in domestic environment. Higher hexanal concentrations were related to new coatings such as painting, wallpapers and laminate floorings. Hexanal concentration decreased with both coating and furniture ages so that this compound may be considered as a tracer of these emissions.

  15. Optimal Timing for Hemoglobin Concentration Determination after Total Knee Arthroplasty: Day 1 versus Day 2

    PubMed Central

    Khalfaoui, Mahdi Yacine; Godavitarne, Charles; Wilkinson, Michael C P

    2017-01-01

    Purpose Postoperative hemoglobin (Hb) determination remains an essential parameter for quantifying blood loss following total knee replacement (TKR) surgery and guiding transfusion practice. In this study we aimed to ascertain the optimal timing for Hb determination postoperatively and assess its relationship to serum hematocrit (Hct). Materials and Methods This was a retrospective cohort analysis of 61 consecutive patients undergoing preoperative, day 1 and day 2 Hb and Hct concentration determination following TKR surgery. This was a single centre study in the United Kingdom. Results The mean fall in Hb concentration at day 1 was 2.9 g/dL in comparison to 3.3 g/dL at day 2. This indicated a significant difference of 0.39 g/dL (p=0.023). A total of 5 patients required blood transfusions following day 2 Hb determination. Postoperative Hct values varied in close relation with the Hb concentration with no significant differences demonstrated. Our study reveals a significant change between day 1 and day 2 Hb concentrations following TKR surgery, with no significant differing information provided through Hct determination. Conclusions Our results support the use of delayed routine testing at day 2 following surgery as it is likely to more accurately reflect ongoing hidden blood loss into the joint cavity and within soft tissue planes. PMID:28231649

  16. An analytical protocol for the determination of total mercury concentrations in solid peat samples.

    PubMed

    Roos-Barraclough, F; Givelet, N; Martinez-Cortizas, A; Goodsite, M E; Biester, H; Shotyk, W

    2002-06-20

    Traditional peat sample preparation methods such as drying at high temperatures and milling may be unsuitable for Hg concentration determination in peats due to the possible presence of volatile Hg species, which could be lost during drying. Here, the effects of sample preparation and natural variation on measured Hg concentrations are investigated. Slight increases in mercury concentrations were observed in samples dried at room temperature and at 30 degrees C (6.7 and 2.48 ng kg(-1) h(-1), respectively), and slight decreases were observed in samples dried at 60, 90 and 105 degrees C (2.36, 3.12 and 8.52 ng kg(-1) h(-1), respectively). Fertilising the peat slightly increased Hg loss (3.08 ng kg(-1) h(-1) in NPK-fertilised peat compared to 0.28 ng kg(-1) h(-1) in unfertilised peat, when averaged over all temperatures used). Homogenising samples by grinding in a machine also caused a loss of Hg. A comparison of two Hg profiles from an Arctic peat core, measured in frozen samples and in air-dried samples, revealed that no Hg losses occurred upon air-drying. A comparison of Hg concentrations in several plant species that make up peat, showed that some species (Pinus mugo, Sphagnum recurvum and Pseudevernia furfuracea) are particularly efficient Hg retainers. The disproportionally high Hg concentrations in these species can cause considerable variation in Hg concentrations within a peat slice. The variation of water content (1.6% throughout 17-cm core, 0.97% in a 10 x 10 cm slice), bulk density (40% throughout 17-cm core, 15.6% in a 10 x 10 cm slice) and Hg concentration (20% in a 10 x 10 cm slice) in ombrotrophic peat were quantified in order to determine their relative importance as sources of analytical error. Experiments were carried out to determine a suitable peat analysis program using the Leco AMA 254, capable of determining mercury concentrations in solid samples. Finally, an analytical protocol for the determination of Hg concentrations in solid peat samples

  17. Placental cortisol and cord serum IGFBP-2 concentrations are important determinants of postnatal weight gain.

    PubMed

    Street, M E; Smerieri, A; Petraroli, A; Cesari, S; Viani, I; Garrubba, M; Rossi, M; Bernasconi, S

    2012-01-01

    There is a need to identify simple biochemical markers at birth that may predict subjects at risk of growth failure and metabolic complications in later life. Limited research to date has been performed on relationships of specific biochemical determinants at birth with postnatal weight gain and growth. We proposed to establish whether placental cortisol and IL-6 concentrations and cord serum IGF-II and IGFBP-2 concentrations influenced postnatal growth. We followed up from pregnancy 23 IUGR and 37 AGA subjects, and determined placental cortisol and IL-6 concentrations, and cord serum IGF-II, and IGFBP-2 concentrations at birth. We obtained height and weight measurements at 3, 6, 12, 24 months and 5 years of age in 20 IUGR and 15 AGA subjects of comparable gestational age. A multiple linear regression model was designed to establish the effect of the placental and cord serum peptides on postnatal linear growth and weight gain. All IUGR subjects had catch-up growth before 2 years of age. Placental cortisol concentration correlated positively with weight gain during the first 5 years of postnatal growth (P<0.05). Subjects with the highest placental cortisol concentrations were those who showed a greater increase in weight. Cord serum IGFBP-2 concentrations correlated positively with weight gain throughout the 5 year observation period (P:0.003). The subjects with the highest concentrations showed a greater weight gain. Placental cortisol and cord serum IGFBP-2 concentrations were related to postnatal weight gain, suggesting that the fetal environment has long-term effects on growth.

  18. Raman Spectroscopy Determination of Hole Concentration in p-Type GaSb

    SciTech Connect

    Maslar JE, Hurst WS, Wang CA

    2007-04-05

    Room temperature p-type GaSb bulk coupled mode spectra were measured as a function of hole concentration. These spectra were obtained using an optical system based on 752.55 nm excitation in order to obtain more sensitivity to bulk GaSb coupled mode scattering than possible with visible wavelength excitation-based systems. A relatively simple spectral model for the electronic contribution to the dielectric function was evaluated for determination of hole concentration from the bulk coupled mode spectra. Optically-derived values for hole concentration were determined by minimizing the sum of the residuals squared between an experimental and simulated spectrum as a function of total hole concentration and a plasmon damping parameter. Hole concentrations obtained from the Raman spectroscopic measurements deviated from the values determined from single field Hall effect measurements that were corrected to account for two band conduction by {approx}20% to {approx}65%. These deviations were attributed to the limitations of the spectral model employed and uncertainties in GaSb materials properties.

  19. Absolute airborne gravimetry

    NASA Astrophysics Data System (ADS)

    Baumann, Henri

    This work consists of a feasibility study of a first stage prototype airborne absolute gravimeter system. In contrast to relative systems, which are using spring gravimeters, the measurements acquired by absolute systems are uncorrelated and the instrument is not suffering from problems like instrumental drift, frequency response of the spring and possible variation of the calibration factor. The major problem we had to resolve were to reduce the influence of the non-gravitational accelerations included in the measurements. We studied two different approaches to resolve it: direct mechanical filtering, and post-processing digital compensation. The first part of the work describes in detail the different mechanical passive filters of vibrations, which were studied and tested in the laboratory and later in a small truck in movement. For these tests as well as for the airborne measurements an absolute gravimeter FG5-L from Micro-G Ltd was used together with an Inertial navigation system Litton-200, a vertical accelerometer EpiSensor, and GPS receivers for positioning. These tests showed that only the use of an optical table gives acceptable results. However, it is unable to compensate for the effects of the accelerations of the drag free chamber. The second part describes the strategy of the data processing. It is based on modeling the perturbing accelerations by means of GPS, EpiSensor and INS data. In the third part the airborne experiment is described in detail, from the mounting in the aircraft and data processing to the different problems encountered during the evaluation of the quality and accuracy of the results. In the part of data processing the different steps conducted from the raw apparent gravity data and the trajectories to the estimation of the true gravity are explained. A comparison between the estimated airborne data and those obtained by ground upward continuation at flight altitude allows to state that airborne absolute gravimetry is feasible and

  20. 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)

  1. Development of a new Method for Determination of Atmospheric Halogen Atom Concentrations

    NASA Astrophysics Data System (ADS)

    Tackett, P. J.; Shepson, P. B.

    2007-05-01

    A flowtube reactor has been developed for the quantitative determination of atmospheric halogen atom concentrations. The technique operates by drawing atmospheric halogen atoms (Cl, Br, I) into a 20 mm diameter quartz flowtube, in which they quickly react with an introduced alkene (trifluoropropene) and NO to produce a halogenated ketone that is detected by gas chromatography with electron capture detection (GC-ECD). This method allows for the "direct" determination of atmospheric halogen atom concentrations, which have so far only been determined by indirect methods, e.g. as inferred from hydrocarbon decay rates. The fluorinated alkene reagent is utilized to increase the final product's ECD sensitivity as well as provide a compound not found in the environment (i.e. very low blanks), leading to greater overall instrument sensitivity. A solid-sorbent sample preconcentrator is used following reaction in the flow tube to increase the sample volume and allow detection of the halogenated ketone product at concentrations in the ppq and ppt range. The halogen monoxide radicals (XO) can also be determined by conversion to X via reaction with NO at the inlet. The resulting halogen atom concentration measurements allow for the greater understanding of halogen atom photochemistry in the lower troposphere. Here we show results from laboratory tests and system calibrations.

  2. 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…

  3. 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.

  4. Rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers

    SciTech Connect

    Snyder, E.A.; Palmes, E.D.

    1985-06-01

    A rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO/sub 2/ for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data.

  5. An inverse radiation model for optical determination of temperature and species concentration: Development and validation

    NASA Astrophysics Data System (ADS)

    Ren, Tao; Modest, Michael F.; Fateev, Alexander; Clausen, Sønnik

    2015-01-01

    In this study, we present an inverse calculation model based on the Levenberg-Marquardt optimization method to reconstruct temperature and species concentration from measured line-of-sight spectral transmissivity data for homogeneous gaseous media. The high temperature gas property database HITEMP 2010 (Rothman et al. (2010) [1]), which contains line-by-line (LBL) information for several combustion gas species, such as CO2 and H2O, was used to predict gas spectral transmissivities. The model was validated by retrieving temperatures and species concentrations from experimental CO2 and H2O transmissivity measurements. Optimal wavenumber ranges for CO2 and H2O transmissivity measured across a wide range of temperatures and concentrations were determined according to the performance of inverse calculations. Results indicate that the inverse radiation model shows good feasibility for measurements of temperature and gas concentration.

  6. 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).

  7. Evaluation of three different histamine concentrations in intradermal testing of normal cats and attempted determination of 'irritant' threshold concentrations for 48 allergens.

    PubMed

    Austel, Michaela; Hensel, Patrick; Jackson, Dawn; Vidyashankar, Anand; Zhao, Ying; Medleau, Linda

    2006-06-01

    The purpose of this study was to determine the optimal histamine concentration and 'irritant' allergen threshold concentrations in intradermal testing (IDT) in normal cats. Thirty healthy cats were tested with three different histamine concentrations and four different concentrations of each allergen. The optimal histamine concentration was determined to be 1: 50,000 w/v (0.05 mg mL(-1)). Using this histamine concentration, the 'irritant' threshold concentration for most allergens was above the highest concentrations tested (4,000 PNU mL(-1) for 41 allergens and 700 PNU mL(-1) for human dander). The 'irritant' threshold concentration for flea antigen was determined to be 1:750 w/v. More than 10% of the tested cats showed positive reactions to Dermatophagoides farinae, Dermatophagoides pteronyssinus, housefly, mosquito and moth at every allergen concentration, which suggests that the 'irritant' threshold concentration for these allergens is below 1,000 PNU mL(-1), the lowest allergen concentration tested. Our results confirm previous studies in indicating that allergen and histamine concentrations used in feline IDT may need to be revised.

  8. The use of minimum selectable concentrations (MSCs) for determining the selection of antimicrobial resistant bacteria.

    PubMed

    Khan, Sadia; Beattie, Tara K; Knapp, Charles W

    2017-03-01

    The use of antimicrobial compounds is indispensable in many industries, especially drinking water production, to eradicate microorganisms. However, bacterial growth is not unusual in the presence of disinfectant concentrations that would be typically lethal, as bacterial populations can develop resistance. The common metric of population resistance has been based on the Minimum Inhibitory Concentration (MIC), which is based on bacteria lethality. However, sub-lethal concentrations may also select for resistant bacteria due to the differences in bacterial growth rates. This study determined the Minimal Selective Concentrations (MSCs) of bacterial populations exposed to free chlorine and monochloramine, representing a metric that possibly better reflects the selective pressures occurring at lower disinfectant levels than MIC. Pairs of phylogenetically similar bacteria were challenged to a range of concentrations of disinfectants. The MSCs of free chlorine and monochloramine were found to range between 0.021 and 0.39 mg L(-1), which were concentrations 1/250 to 1/5 than the MICs of susceptible bacteria (MIC susc ). This study indicates that sub-lethal concentrations of disinfectants could result in the selection of resistant bacterial populations, and MSCs would be a more sensitive indicator of selective pressure, especially in environmental systems.

  9. Determining median urinary iodine concentration that indicates adequate iodine intake at population level.

    PubMed Central

    Delange, François; de Benoist, Bruno; Burgi, Hans

    2002-01-01

    OBJECTIVE: Urinary iodine concentration is the prime indicator of nutritional iodine status and is used to evaluate population-based iodine supplementation. In 1994, WHO, UNICEF and ICCIDD recommended median urinary iodine concentrations for populations of 100- 200 micro g/l, assuming the 100 micro g/l threshold would limit concentrations <50 micro g/l to determine the frequency distribution of urinary iodine in iodine-replete populations (schoolchildren and adults) and the proportion of concentrations <50 micro g/l. METHOD: A questionnaire on frequency distribution of urinary iodine in iodine-replete populations was circulated to 29 scientific groups. FINDINGS: Nineteen groups reported data from 48 populations with median urinary iodine concentrations >100 micro g/l. The total population was 55 892, including 35 661 (64%) schoolchildren. Median urinary iodine concentrations were 111-540 (median 201) micro g/l for all populations, 100-199 micro g/l in 23 (48%) populations and >/=200 micro g/l in 25 (52%). The frequencies of values <50 micro g/l were 0-20.8 (mean 4.8%) overall and 7.2% and 2.5% in populations with medians of 100-199 micro g/l and >200 micro g/l, respectively. The frequency reached 20% only in two places where iodine had been supplemented for <2 years. CONCLUSION: The frequency of urinary iodine concentrations <50 micro g/l in populations with median urinary iodine concentrations >/=100 micro g/l has been overestimated. The threshold of 100 micro g/l does not need to be increased. In populations, median urinary iodine concentrations of 100-200 micro g/l indicate adequate iodine intake and optimal iodine nutrition. PMID:12219154

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

    SciTech Connect

    Santos, Andrew P.; Panagiotopoulos, Athanassios Z.

    2016-01-28

    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)

  11. Determination of D- and L-alanine concentrations using a pyruvic acid sensor.

    PubMed

    Inaba, Yohei; Hamada-Sato, Naoko; Kobayashi, Takeshi; Imada, Chiaki; Watanabe, Etsuo

    2003-08-01

    The concentrations of D- and L-alanine in bivalves are useful as indicators of environmental pollution. Amino acid oxidase with a low substrate specificity catalyzes the oxidation of various amino acids. Among the various amino acids, pyruvic acid can be generated from alanine only by the catalytic oxidative reaction of this oxidase. Therefore, in this study, the concentrations of D- and L-alanine were determined from the concentration of pyruvic acid, which was determined from the consumption of oxygen based on the oxidative reaction of pyruvate oxidase. From this point of view, there is a very strong possibility that biosensors utilizing enzymes with a low substrate specificity can be developed. The results obtained were as follows. (1) The optimum conditions for the use of pyruvic acid sensor were as follows: temperature of 25 degrees C, pH of 6.8, flow rate of 0.1 ml/min, thiamin diphosphate concentration of 1.5 mM, and injection volume of 50 microl. (2) D-Alanine and L-alanine optimally reacted with D- and L-amino acid oxidase at 30 degrees C, pH 8.2, for 30 min and at 37 degrees C, pH 7.8, for 90 min, respectively. (3) The linear relationships between the concentrations of D- and L-alanine and the output of the sensor were obtained at 3.56-106.8 microg of D-alanine and 5.34-71.3 microg of L-alanine. (4) The concentrations of D- and L-alanine in Meretrix iusoria, Patinopecten yessonsi, and Corbicula leana obtained by the proposed assay were in good agreement with those determined by a conventional method.

  12. 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.

  13. Comparison of various hours living fission products for absolute power density determination in VVER-1000 mock up in LR-0 reactor.

    PubMed

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

    2015-11-01

    Measuring power level of zero power reactor is a quite difficult task. Due to the absence of measurable cooling media heating, it is necessary to employ a different method. The gamma-ray spectroscopy of fission products induced within reactor operation is one of possible ways of power determination. The method is based on the proportionality between fission product buildup and released power. The (92)Sr fission product was previously preferred as nuclide for LR-0 power determination for short-time irradiation experiments. This work aims to find more appropriate candidates, because the (92)Sr, however suitable, has a short half-life, which limits the maximal measurable amount of fuel pins within a single irradiation batch. The comparison of various isotopes is realized for (92)Sr, (97)Zr, (135)I, (91)Sr, and (88)Kr. The comparison between calculated and experimentally determined (C/E-1 values) net peak areas is assessed for these fission products. Experimental results show that studied fission products, except (88)Kr, are in comparable agreement with (92)Sr results. Since (91)Sr has notably higher half-life than (92)Sr, (91)Sr seems to be more appropriate marker in experiments with a large number of measured fuel pins.

  14. Ion beam methods to determine trace heavy metals concentrations and sources in urban airsheds

    NASA Astrophysics Data System (ADS)

    Cohen, David D.; Stelcer, Ed; Garton, David

    2002-05-01

    Unique data for Australia on the concentration of selected metals in fine particle ambient air pollution is presented for urban, industrial and rural sites along 300 km section of the eastern coast line of Australia around Sydney. IBA techniques were used to determine over 25 different chemical species in the air including, H, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Se and Pb. This included many trace metals at concentrations around 1 ng/m 3 of air sampled.

  15. Determination of calcium concentrations in cells and tissue with fluorescence lifetime imaging (FILM)

    NASA Astrophysics Data System (ADS)

    Gensch, T.; Wirth, M.

    2011-03-01

    The determination of ion concentrations in cells - in particular in neurons - is very important for understanding cell function and life. Calcium is an ubiquitous messenger in almost all cell types. Fluorescence lifetime imaging (FLIM) can be of advantage over intensity based fluorescence microscopy, when comparisons between micro-domains of one cell or between different cells of one cell type are performed. Several organic chromophores have been tested in cuvette experiments as well as in living cells and cell tissue with respect to their applicability in FLIM studies. The calcium concentration changes in several cell types were investigated by FLIM with two-photon excitation.

  16. 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.

  17. 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.

  18. [NIRS method for determination of meat and bone meal content in ruminant concentrates].

    PubMed

    Yang, Zeng-ling; Han, Lu-jia; Li, Qiong-fei; Liu, Xian

    2008-06-01

    Feed contaminated with MBM is commonly accepted as the main transmission carrier of bovine spongiform encephalopathy (BSE). To prevent BSE many countries have banned MBM as a feed ingredient. In the People's Republic of China, the ban was first applied to ruminant feed. In order to investigate the feasibility of near infrared diffuse reflectance spectroscopy method for rapidly quantitative determination of meat and bone meal content in ruminant concentrates, 225 representatively commercial ruminant concentrates samples and 75 meat and bone meal (including cattle, sheep, pig and poultry meat and bone meal) samples were collected in the People's Republic of China. Two hundred twenty five ruminant concentrates samples of adulterated meat and bone meal (0.5%-35%) were prepared including 135 calibration samples and 90 independent validation samples. For the calibration set samples, 3 samples were prepared at each concentration. For validation set samples, 2 samples were prepared at each concentration. Any one commercial ruminant concentrates was used once only. The spectra were scanned by raster near infrared diffuse reflectance spectroscopy instrument, and the effect of spectrum pretreatment methods (mathematic pretreatments and scatter correction) and spectrum region (visible and NIR) on the calibration results was considered. The calibration equation was established by modified partial least squares method. The result showed that the calibration gave r2 of 0.979, a standard error of calibration (SEC) of 1.522% and a standard error of cross validation (SECV) of 1.582%. The 90 independent validation samples were used to validate the quantitative equation. The r2, a standard error of prediction (SEP) and ratio of performance to standard deviation (RPD) were 0.972, 1.764% and 5.99 respectively. The results of this study indicated that near infrared diffuse reflectance spectroscopy method could provide rapidly quantitative prediction for meat and bone meal percent in

  19. Highly concentrated emulsions: 1. Average drop size determination by analysis of incoherent polarized steady light transport.

    PubMed

    Paruta-Tuarez, Emilio; Fersadou, Hala; Sadtler, Véronique; Marchal, Philippe; Choplin, Lionel; Baravian, Christophe; Castel, Christophe

    2010-06-01

    The analysis of incoherent polarized steady light transport is reported as a convenient technique for the drop size determination in highly concentrated oil-in-water emulsions. The studied system consists in heptane-in-water emulsions stabilized with a copolymeric surfactant (Synperonic PE®/L64). Hundred grams of parent emulsions, at two volume fractions of dispersed phase (φ=0.958 and 0.937) were prepared using a semi-batch process. Then, they were diluted with the aqueous phase to obtain volume fractions ranging from 0.886 to 0.958. The use of a copolymeric surfactant allows the dilution of the highly concentrated emulsions without any change in the particle size distribution as confirmed by laser diffraction measurements. We found that the polarization technique allows the determination of the film thickness between water drops rather than their sizes. Consequently, we propose a geometrical relationship to determine an average drop size from the film thickness. The sensitivity of this alternative technique to detect changes in average drop size was studied by changing some process and formulation parameters. Drop size determination in highly concentrated emulsions via this method is useful since the measurement protocol neither involves dilution nor induces structural changes in the emulsion.

  20. 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.

  1. 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.

  2. 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.

  3. Absolute multilateration between spheres

    NASA Astrophysics Data System (ADS)

    Muelaner, Jody; Wadsworth, William; Azini, Maria; Mullineux, Glen; Hughes, Ben; Reichold, Armin

    2017-04-01

    Environmental effects typically limit the accuracy of large scale coordinate measurements in applications such as aircraft production and particle accelerator alignment. This paper presents an initial design for a novel measurement technique with analysis and simulation showing that that it could overcome the environmental limitations to provide a step change in large scale coordinate measurement accuracy. Referred to as absolute multilateration between spheres (AMS), it involves using absolute distance interferometry to directly measure the distances between pairs of plain steel spheres. A large portion of each sphere remains accessible as a reference datum, while the laser path can be shielded from environmental disturbances. As a single scale bar this can provide accurate scale information to be used for instrument verification or network measurement scaling. Since spheres can be simultaneously measured from multiple directions, it also allows highly accurate multilateration-based coordinate measurements to act as a large scale datum structure for localized measurements, or to be integrated within assembly tooling, coordinate measurement machines or robotic machinery. Analysis and simulation show that AMS can be self-aligned to achieve a theoretical combined standard uncertainty for the independent uncertainties of an individual 1 m scale bar of approximately 0.49 µm. It is also shown that combined with a 1 µm m‑1 standard uncertainty in the central reference system this could result in coordinate standard uncertainty magnitudes of 42 µm over a slender 1 m by 20 m network. This would be a sufficient step change in accuracy to enable next generation aerospace structures with natural laminar flow and part-to-part interchangeability.

  4. Multimode Surface Functional Group Determination: Combining Steady-State and Time-Resolved Fluorescence with X-ray Photoelectron Spectroscopy and Absorption Measurements for Absolute Quantification.

    PubMed

    Fischer, Tobias; Dietrich, Paul M; Unger, Wolfgang E S; Rurack, Knut

    2016-01-19

    The quantitative determination of surface functional groups is approached in a straightforward laboratory-based method with high reliability. The application of a multimode BODIPY-type fluorescence, photometry, and X-ray photoelectron spectroscopy (XPS) label allows estimation of the labeling ratio, i.e., the ratio of functional groups carrying a label after reaction, from the elemental ratios of nitrogen and fluorine. The amount of label on the surface is quantified with UV/vis spectrophotometry based on the molar absorption coefficient as molecular property. The investigated surfaces with varying density are prepared by codeposition of 3-(aminopropyl)triethoxysilane (APTES) and cyanoethyltriethoxysilane (CETES) from vapor. These surfaces show high functional group densities that result in significant fluorescence quenching of surface-bound labels. Since alternative quantification of the label on the surface is available through XPS and photometry, a novel method to quantitatively account for fluorescence quenching based on fluorescence lifetime (τ) measurements is shown. Due to the complex distribution of τ on high-density surfaces, the stretched exponential (or Kohlrausch) function is required to determine representative mean lifetimes. The approach is extended to a commercial Rhodamine B isothiocyanate (RITC) label, clearly revealing the problems that arise from such charged labels used in conjunction with silane surfaces.

  5. Determination of thorium concentrations and activity ratios in silicate rocks by alpha spectrometry.

    PubMed

    dos Santos, R N; Marques, L S; Nicolai, S H A; Ribeiro, F B

    2004-01-01

    A detailed radiochemical procedure for alpha spectrometry measurements of thorium concentrations and of 230Th/232Th activity ratios in silicates is presented. The Th behaviour, during each step of the chemical process, was investigated by using a 234Th tracer, which is a gamma-ray emitter. The described chemical processing provides relatively high thorium yields, which varied between 56% and 88%, in the analysis of GB-1 (granite) and BB-1 (basalt) Brazilian geological standards. Also, the application of the established radiochemical method allowed a determination of both Th concentrations and activity ratios with high reproducibility, on the order of 2%. The estimation of the concentration result accuracy is also about 2%, which was calculated by using published data obtained from neutron activation analysis as reference values.

  6. Review of methods for determination of total protein and peptide concentration in biological samples.

    PubMed

    Sapan, Christine V; Lundblad, Roger L

    2015-04-01

    Clinical proteomics can be defined as the use of proteomic technologies to identify and measure biomarkers in fluids and tissues. The current work is intended to review various methods used for the determination of the total concentration of protein or peptide in fluids and tissues and the application of such methods to clinical proteomics. Specifically, this article considers the approaches to the measurement of total protein concentration, not the measurement of the concentration of a specific protein or group of proteins in a larger mixture of proteins. The necessity of understanding various concepts such as fit-for-use, quality-by-design, and other regulatory elements is discussed, as is the significance of using suitable standards for the protein quality of various samples.

  7. Determination of tritium concentrations in humans before the development of a nuclear power plant in Turkey.

    PubMed

    Dizman, Serdar; Yilmaz, Adnan; Keser, Recep

    2015-01-01

    The most widely used method to determine the level of tritium in humans is testing urine. Tritium concentrations in urine samples of 100 persons aged 18-66 years selected randomly from a pilot region in Turkey were analysed. The average activity concentration of urine samples was 4.66 ± 1.94 Bq L(-1) and the maximum activity concentration was 27.91 Bq L(-1). The minimum detectable activity was 2.38 Bq L(-1). The annual effective dose from tritium was also evaluated on the basis of the measurement results and reference values recommended by the International Commission on Radiological Protection. The effective doses for males and females were 4.56 and 3.54 nSv, respectively. These results were lower than the permissible annual effective dose for members of the public.

  8. 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.

  9. 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.

  10. Uncertainties in risk assessment for the determination of drinking water pollutant concentrations: Cryptosporidium case study.

    PubMed

    Fewtrell, L; Macgill, S M; Kay, D; Casemore, D

    2001-02-01

    There is a growing acknowledgement of the need to recognise uncertainties in the estimation of waterborne risks. In this paper, the strength of the science available to characterise Cryptosporidium risks in drinking water is investigated, in particular the determination of oocyst concentrations at various points in the chain of water supply. A recently developed scientific quality audit framework is used as a tool to guide this investigation. The framework systematically reveals the relatively greater strength of the science for the "upstream" elements (estimation of concentrations in environmental reservoirs) than for the "downstream" elements (concentrations in distribution). It is the downstream elements that have greater bearing on human health and public policy issues. It is noted that the adoption of new monitoring Regulations is likely to prompt action to strengthen knowledge of these downstream elements in the future.

  11. 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.

  12. Integrated X-ray detection system for determination of nuclear material concentration

    SciTech Connect

    Sung-Woo Kwak; Jung-Ki Shin; Seunghoon Park

    2015-07-01

    An integrated system of X-ray Absorption Spectrometry (XAS), also called L-edge densitometry for uranium (LED) and X-ray Fluorescence spectrometry (XRF) is designed using Monte Carlo simulation for determining concentration of uranium and minor actinides for safeguard. The system can be useful to determination uranium and minor actinide, such as plutonium, neptunium, and etc., concurrently. The equipment is compact compared to the K-edge densitometer with high purity germanium detector which needs liquid nitrogen cooling since a low energy X-ray source is used. The system has been validated from simulation and analysis of the transmitted and reflected spectrum. The concentrations of nuclear material samples are obtained from this study. (authors)

  13. Rapid determination of surfactant critical micelle concentrations using pressure-driven flow with capillary electrophoresis instrumentation.

    PubMed

    Stanley, F E; Warner, A M; Schneiderman, E; Stalcup, A M

    2009-11-20

    This work demonstrates a novel, convenient utilization of capillary electrophoresis (CE) instrumentation for the determination of critical micelle concentrations (CMCs). Solution viscosity differences across a range of surfactant concentrations were monitored by hydrodynamically forcing an analyte towards the detector. Upon reaching the surfactant's CMC value, migration times were observed to change drastically. CMC values for four commonly employed anionic surfactants were determined-sodium dodecyl sulfate: 8.1mM; sodium caprylate: 300 mM; sodium decanoate: 86 mM; sodium laurate: 30 mM; and found to be in excellent agreement with values previously reported in the literature. The technique was then applied to the less well-characterized nonionic surfactants poly(oxyethylene) 8 myristyl ether (CMC approximately 9 M), poly(oxyethylene) 8 decyl ether (CMC approximately 0.95 mM) and poly(oxyethylene) 4 lauryl ether.

  14. 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.

  15. [Determination of high concentrations of rubidium chloride by ICP-OES].

    PubMed

    Zhong, Yuan; Sun, Bai; Li, Hai-jun; Wang, Tao; Li, Wu; Song, Peng-sheng

    2015-01-01

    The method of ICP-OES for the direct determination of high content of rubidium in rubidium chloride solutions was studied through mass dilution method and optimizing parameters of the instrument in the present paper. It can reduce the times of dilution and the error introduced by the dilution, and improve the accuracy of determination results of rubidium. Through analyzing the sensitivity of the three detection spectral lines for rubidium ion, linearly dependent coefficient and the relative errors of the determination results, the spectral line of Rb 780. 023 nm was chosen as the most suitable wavelength to measure the high content of rubidium in the rubidium chloride solutions. It was found that the instrument parameters of ICP-OES such as the atomizer flow, the pump speed and the high-frequency power are the major factors for the determination of rubidium ion in the rubidium chloride solutions. As we know instrument parameters of ICP-OES have an important influence on the atomization efficiency as well as the emissive power of the spectral lines of rubidium, they are considered as the significant factors for the determination of rubidium. The optimization parameters of the instrument were obtained by orthogonal experiments and further single factor experiment, which are 0. 60 L . min-1 of atomizer flow, 60 r . min-1 of pump speed, and 1 150 W of high-frequency power. The same experiments were repeated a week later with the optimization parameters of the instrument, and the relative errors of the determination results are less than 0. 5% when the concentration of rubidium chloride ranged from 0. 09% to 0. 18%. As the concentration of rubidium chloride is 0. 06%, the relative errors of the determination results are -1. 7%. The determination of lithium chloride and potassium chloride in the high concentration of the aqueous solutions was studied under the condition of similar instrument parameters. It was found by comparison that the determination results of lithium

  16. Ethanol vapor above skin: determination by a gas sensor instrument and relationship with plasma concentration.

    PubMed

    Giles, H G; Meggiorini, S; Renaud, G E; Thiessen, J J; Vidins, E I; Compton, K V; Saldivia, V; Orrego, H; Israel, Y

    1987-06-01

    Studies with a new instrument show that blood ethanol concentrations in rats and humans can be estimated by measurement of ethanol vapor above the skin. After intravenous bolus administration of ethanol (1 g/kg) to rats a novel device based on the Figaro sensor was placed above the animal's abdomen. Plasma and skin vapor ethanol concentrations, analyzed by gas chromatography and sensor, respectively, declined in parallel (r = 0.96). In healthy human subjects, plasma and skin vapor concentrations, measured on the palm, also declined in parallel after intravenous ethanol infusion (1 hr, 0.5 g/kg), r = 0.99. In 10 alcoholic liver disease outpatients attending clinic in whom plasma ethanol concentrations ranged from 32-304 mg/dl, the correlation of plasma ethanol determined directly by gas chromatography and indirectly by skin vapor analysis was slope = 0.93, intercept = 1.8, r = 0.94. In controlled studies, skin vapor measurements are comparable with breathalyzer determinations; they may be performed in situations where breathalyzer measurements are inconvenient or where continuous monitoring is desirable.

  17. Determination of Dicarboxylic Acid Concentrations in Surface Microlayer of Dams in Okinawa, Japan

    NASA Astrophysics Data System (ADS)

    Kotani, Y.; Taira, N.; Kamizato, C.; Arakaki, T.

    2008-12-01

    The surface microlayer (SML) is a thin layer that forms the boundary between atmosphere and water body. The SML includes fatty acid, protein and other organic compounds. It is the site across which the atmosphere-water system interacts. It also has unique chemical, physical and biological properties, which are very different from those of the underlying water. We determined concentrations of dicarboxylic acids (oxalic, malic, malonic, succinic, adipic, phthalic, fumaric, and maleic acids) in the SML, and compared with those of underlying bulk water. Dicarboxylic acids are the major organic compounds found in atmospheric aerosols, which can be derived from the wind-blown SML. The sampling sites we chose were dams in Okinawa, Japan. The SML was sampled by using a glass plate method. Concentrations of dicarboxylic acids were determined by using a GC-FID after derivatization. The results showed that the dicarboxylic acid concentrations were 2- 17 times higher than those of the underlying water. We have also found that the concentrations of some of the dicarboxylic acids were lower in the afternoon than those in the morning at the same sampling site.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 40 CFR 63.7943 - How do I determine the average VOHAP concentration of my remediation material?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... concentration of my remediation material? 63.7943 Section 63.7943 Protection of Environment ENVIRONMENTAL... Remediation Performance Tests § 63.7943 How do I determine the average VOHAP concentration of my remediation material? (a) General requirements. You must determine the average total VOHAP concentration of...

  6. 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

    ... concentration of my remediation material? 63.7943 Section 63.7943 Protection of Environment ENVIRONMENTAL... Remediation Performance Tests § 63.7943 How do I determine the average VOHAP concentration of my remediation material? (a) General requirements. You must determine the average total VOHAP concentration of...

  7. 40 CFR 63.7943 - How do I determine the average VOHAP concentration of my remediation material?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... concentration of my remediation material? 63.7943 Section 63.7943 Protection of Environment ENVIRONMENTAL... Remediation Performance Tests § 63.7943 How do I determine the average VOHAP concentration of my remediation material? (a) General requirements. You must determine the average total VOHAP concentration of...

  8. 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

    ... concentration of my remediation material? 63.7943 Section 63.7943 Protection of Environment ENVIRONMENTAL... Remediation Performance Tests § 63.7943 How do I determine the average VOHAP concentration of my remediation material? (a) General requirements. You must determine the average total VOHAP concentration of...

  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. 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.

  11. 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.; Wang, Y.

    2011-06-01

    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. 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 to improve the air quality over Beijing, emission control strategy should focus on the regional scale instead of the local scale.

  12. 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.

  13. Fluorescence-based determination of the copper concentration in drinking water

    NASA Astrophysics Data System (ADS)

    Hötzer, Benjamin; Scheu, Timo; Jung, Gregor; Castritius, Stefan

    2013-05-01

    Copper is a heavy metal, which is used in heat and electrical conductors and in a multitude of alloys in the technical context. Moreover, it is a trace element that is essential for the life of organisms but can cause toxic effects in elevated concentrations. Maximum limits in water and beverages exist. Here, the decrease of the fluorescence lifetime of green fluorescent protein (GFP) by Förster resonance energy transfer is used to measure the copper ion concentration in drinking water. Therefore, a system is developed that is based on a GFP sample in a predefined concentration. The GFP mutant can be excited with blue light. For binding of copper ions, a His-tag is included in the GFP. After measuring the fluorescence lifetime of pure GFP, the copper determination of the sample is performed by lifetime measurement. Therefore, the lifetime can be assigned to the copper concentration of the GFP-doped drinking water sample. In summary, a method for the quantification of copper ions based on changes of the fluorescence lifetime of GFP is developed, and the measurement of the copper concentration in water samples is performed.

  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.

  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. 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

    2011-12-05

    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.

  17. 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.

  18. Absolute quantification of proteins by LCMSE: a virtue of parallel MS acquisition.

    PubMed

    Silva, Jeffrey C; Gorenstein, Marc V; Li, Guo-Zhong; Vissers, Johannes P C; Geromanos, Scott J

    2006-01-01

    Relative quantification methods have dominated the quantitative proteomics field. There is a need, however, to conduct absolute quantification studies to accurately model and understand the complex molecular biology that results in proteome variability among biological samples. A new method of absolute quantification of proteins is described. This method is based on the discovery of an unexpected relationship between MS signal response and protein concentration: the average MS signal response for the three most intense tryptic peptides per mole of protein is constant within a coefficient of variation of less than +/-10%. Given an internal standard, this relationship is used to calculate a universal signal response factor. The universal signal response factor (counts/mol) was shown to be the same for all proteins tested in this study. A controlled set of six exogenous proteins of varying concentrations was studied in the absence and presence of human serum. The absolute quantity of the standard proteins was determined with a relative error of less than +/-15%. The average MS signal responses of the three most intense peptides from each protein were plotted against their calculated protein concentrations, and this plot resulted in a linear relationship with an R(2) value of 0.9939. The analyses were applied to determine the absolute concentration of 11 common serum proteins, and these concentrations were then compared with known values available in the literature. Additionally within an unfractionated Escherichia coli lysate, a subset of identified proteins known to exist as functional complexes was studied. The calculated absolute quantities were used to accurately determine their stoichiometry.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Absolute Positioning Using the Global Positioning System

    DTIC Science & Technology

    1994-04-01

    Global Positioning System ( GPS ) has becom a useful tool In providing relativ survey...Includes the development of a low cost navigator for wheeled vehicles. ABSTRACT The Global Positioning System ( GPS ) has become a useful tool In providing...technique of absolute or point positioning involves the use of a single Global Positioning System ( GPS ) receiver to determine the three-dimenslonal

  4. 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

  5. Simultaneous Determination of Benzene and Toluene in Pesticide Emulsifiable Concentrate by Headspace GC-MS

    PubMed Central

    Jiang, Hua; Yang, Jing; Fan, Li; Li, Fengmin; Huang, Qiliang

    2013-01-01

    The toxic inert ingredients in pesticide formulations are strictly regulated in many countries. In this paper, a simple and efficient headspace-gas chromatography-mass spectrometry (HSGC-MS) method using fluorobenzene as an internal standard (IS) for rapid simultaneous determination of benzene and toluene in pesticide emulsifiable concentrate (EC) was established. The headspace and GC-MS conditions were investigated and developed. A nonpolar fused silica Rtx-5 capillary column (30 m × 0.20 mm i.d. and 0.25 μm film thickness) with temperature programming was used. Under optimized headspace conditions, equilibration temperature of 120°C, equilibration time of 5 min, and sample size of 50 μL, the regression of the peak area ratios of benzene and toluene to IS on the concentrations of analytes fitted a linear relationship well at the concentration levels ranging from 3.2 g/L to 16.0 g/L. Standard additions of benzene and toluene to blank different matrix solutions 1ead to recoveries of 100.1%–109.5% with a relative standard deviation (RSD) of 0.3%–8.1%. The method presented here stands out as simple and easily applicable, which provides a way for the determination of toxic volatile adjuvant in liquid pesticide formulations. PMID:23607048

  6. Pre-concentration and determination of tartrazine dye from aqueous solutions using modified cellulose nanosponges.

    PubMed

    Shiralipour, Roohollah; Larki, Arash

    2017-01-01

    In this study, a new absorbent based on cellulose nanosponges modified with methyltrioctylammonium chloride (aliquat 336) was prepared and used for pre-concentration, removal and determination of tartrazine dye, using UV-vis spectrophotometry. This adsorbent was fully characterized using various instrumental techniques such as SEM, FTIR and XRD spectra. The pre-concentration and removal procedures were studied in column and batch modes, respectively. The effects of parameters such as pH of the aqueous medium, methyltrioctylammounium chloride dose, adsorbent amount, desorbing conditions and interfering ions on the adsorption of tartrazine were investigated and optimized. The fitting experimental data with conventional isotherm models revealed that the adsorption followed the Brunauer-Emmett-Teller (BET) model and the maximum adsorption capacity for tartrazine was 180mg/g with modified nanosponges. Under the optimized conditions, the calibration curve was linear over the range of 2-300ng/mL and the limit of detection was 0.15ng/mL. The relative standard deviation (RSD) for 20 and 100ng/mL of tartrazine were 3.1% and 1.5%, respectively. The proposed method was applied for pre-concentration and determination of tartrazine dye in different water samples.

  7. 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

  8. Determination of environemtal radioactivity at two different concentration levels. Results of two recent IAEA intercomparisons

    NASA Astrophysics Data System (ADS)

    Suschny, O.

    1984-06-01

    In two recent intercomparisons, the performance of laboratories in the determination of radionuclides in environmental materials and in food was again investigated. The first dealt with stroniium isotopes and 137Cs in liquid milk at levels of nanocuries per litre, the second with the same radionuclides and others in fresh water, at levels of picocuries per litre. In both intercomparisons the results could be compared with known input values. Thirty-two laboratories from 14 countries participated in the milk intercomparison. Except for 137Cs, the number of outlying results was small (6%). The standard deviation was highest for 89Sr (54%). The differences of the overall means from the input values were not significant. In the second intercomparison, 32 laboratories from 19 countries returned 108 results. The lower concentration level led to a wider scatter of the data, 20% had to be rejected, the average standard deviation was 32% and the average difference of the overall means from the input values 28%. The positive bias found for all the radionuclides was probably due to incomplete separations. In conclusion 90Sr and 137Cs were adequately determined in the first intercomparisons (higher concentration), 89Sr was not. At the lower concentration level used in the second intercomparison, all the radionuclides investigated, except tritium, were found to present analytical problems.

  9. 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).

  10. 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.

  11. 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.

  12. 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.

  13. Direct determination of free metal concentration by implementing stripping chronopotentiometry as the second stage of AGNES.

    PubMed

    Parat, C; Authier, L; Aguilar, D; Companys, E; Puy, J; Galceran, J; Potin-Gautier, M

    2011-10-21

    The electroanalytical technique Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) has been extended by applying stripping chronopotentiometry (SCP) as the re-oxidation stage in the determination of the free concentration of Zn(2+), Cd(2+) and Pb(2+). This new approach, called AGNES-SCP, has been implemented with screen-printed electrodes (SPE) and the standard Hanging Mercury Drop Electrode (HMDE). Clear advantages of this variant have been shown: (i) the easy resolution of the peaks of different metals present in mixtures and (ii) the sparing of blanks. A rigorous computation of the faradaic charge along the SCP stage takes into account the contribution of other oxidants, which can be efficiently measured at the end of the deposition stage of AGNES. The free Cd concentration determined in an oxalate solution at pH 6 with an HMDE as the working electrode agreed well with values obtained with a Cd Ion Selective Electrode. The free metal concentration measured using an SPE for the system Cd and nitrilotriacetic acid (NTA) at pH = 4.8 also conformed well with Visual MINTEQ results.

  14. 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.

  15. Determination of trace elements and their concentrations in clay balls: problem of geophagia practice in Ghana.

    PubMed

    Arhin, Emmanuel; Zango, Musah S

    2017-02-01

    Ten samples of 100 g weight were subsampled from 1400 g of the clay balls from which the contained trace element levels were determined by X-ray fluorescence technique. The results of trace elements in the clay balls were calibrated using certified reference materials "MAJMON" and "BH-1." The results showed elevated concentrations but with different concentration levels in the regions, particularly with arsenic, chromium, cobalt, Cs, Zr and La. These trace elements contained in the clay balls are known to be hazardous to human health. Thence the relatively high concentrations of these listed trace elements in clay balls in the three regions, namely Ashanti, Upper East and Volta, which are widely sold in markets in Ghana, could present negative health impact on consumers if consumed at 70 g per day or more and on regular basis. On the basis of these, the study concludes an investigation to establish breakeven range for trace element concentrations in the clay balls as it has been able to demonstrate the uneven and elevated values in them. The standardized safe ranges of trace elements will make the practice safer for the people that ingest clay balls in Ghana.

  16. 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).

  17. Improved in-cell structure determination of proteins at near-physiological concentration

    PubMed Central

    Ikeya, Teppei; Hanashima, Tomomi; Hosoya, Saori; Shimazaki, Manato; Ikeda, Shiro; Mishima, Masaki; Güntert, Peter; Ito, Yutaka

    2016-01-01

    Investigating three-dimensional (3D) structures of proteins in living cells by in-cell nuclear magnetic resonance (NMR) spectroscopy opens an avenue towards understanding the structural basis of their functions and physical properties under physiological conditions inside cells. In-cell NMR provides data at atomic resolution non-invasively, and has been used to detect protein-protein interactions, thermodynamics of protein stability, the behavior of intrinsically disordered proteins, etc. in cells. However, so far only a single de novo 3D protein structure could be determined based on data derived only from in-cell NMR. Here we introduce methods that enable in-cell NMR protein structure determination for a larger number of proteins at concentrations that approach physiological ones. The new methods comprise (1) advances in the processing of non-uniformly sampled NMR data, which reduces the measurement time for the intrinsically short-lived in-cell NMR samples, (2) automatic chemical shift assignment for obtaining an optimal resonance assignment, and (3) structure refinement with Bayesian inference, which makes it possible to calculate accurate 3D protein structures from sparse data sets of conformational restraints. As an example application we determined the structure of the B1 domain of protein G at about 250 μM concentration in living E. coli cells. PMID:27910948

  18. 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.

  19. [Rapid determination of ethephon residues in concentrated pineapple juice by head-space gas chromatography].

    PubMed

    Chu, X G; Yong, W; Cai, H X; Pan, J W

    2001-05-01

    The method developed is based on the special property that ethephon can be easily decomposed into ethene in alkaline solution by heating. Certain amount of concentrated KOH solution was added to the sample and heated at 70 degrees C. Then, 1 mL of the gas above the sample was injected into a gas chromatograph by head-space sampler for the determination of the target compound with external standard quantitation method. The detection limit was 0.025 mg/kg and the fortified recoveries of ethephon in concentrated pineapple juice (60 +/- 1) Brix at the range of 0.1 mg/kg-10 mg/kg were 92%-98% (n = 8, for each level). The relative standard deviations were 3.99%-7.94%.

  20. 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.

  1. Dosimetry Determines the Initial OH Radical Concentration in Fast Photochemical Oxidation of Proteins (FPOP)

    NASA Astrophysics Data System (ADS)

    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.

  2. A cost-benefit analysis of methods for the determination of biomass concentration in wastewater treatment.

    PubMed

    Hernandez, J E; Bachmann, R T; Edyvean, R G J

    2006-01-01

    The measurement of biomass concentration is important in biological wastewater treatment. This paper compares the accuracy and costs of the traditional volatile suspended solids (VSS) and the proposed suspended organic carbon (SOC) methods. VSS and SOC values of a dilution system were very well correlated (R(2)=0.9995). VSS and SOC of 16 samples were determined, the mean SOC/VSS ratio (0.52, n=16, sigma=0.01) was close to the theoretical value (0.53). For costing analysis, two hypothetical cases were analysed. In case A, it is assumed that 108 samples are analysed annually from two continuous reactors. Case B represents a batch experiment to be carried out in 24 incubated serum bottles. The savings, when using the SOC method, were 11,987 pounds for case A and 90 pounds for case B. This study suggests the use of SOC method as a time saving and lower cost biomass concentration measurement.

  3. 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.

  4. Determination of soluble aluminium concentration in alkaline humic water using atomic absorption spectrophotometry.

    PubMed

    Nguyen, K L; Lewis, D M; Jolly, M; Robinson, J

    2004-11-01

    The steps of the standard method to determine soluble aluminium concentration are filtering, followed by acidifying, then analysing with the atomic absorption spectrophotometer (AAS). When applied to alkaline humic water, acidification gives rise to the formation of humic acid as a brown particulate matter. Of the total soluble aluminium in the original water, 49-61% forms complexes with the particulate humic acid upon acidification. Although the AAS is capable of detecting the binding aluminium, the particulate nature of humic acid easily induces inaccurate readings as a result of the non-uniform distribution of the particulate matter. A more precise analysis of soluble aluminium concentration of alkaline humic water is shown to be achievable in basicified solutions instead. Basicified solutions keep humic acid in the soluble form; hence maintain the homogeneity of the sample.

  5. Room-Temperature Determination of Two-Dimensional Electron Gas Concentration and Mobility in Heterostructures

    NASA Technical Reports Server (NTRS)

    Schacham, S. E.; Mena, R. A.; Haugland, E. J.; Alterovitz, S. A.

    1993-01-01

    A technique for determination of room-temperature two-dimensional electron gas (2DEG) concentration and mobility in heterostructures is presented. Using simultaneous fits of the longitudinal and transverse voltages as a function of applied magnetic field, we were able to separate the parameters associated with the 2DEG from those of the parallel layer. Comparison with the Shubnikov-de Haas data derived from measurements at liquid helium temperatures proves that the analysis of the room-temperature data provides an excellent estimate of the 2DEG concentration. In addition we were able to obtain for the first time the room-temperature mobility of the 2DEG, an important parameter to device application. Both results are significantly different from those derived from conventional Hall analysis.

  6. Single Nanotube Spectral Imaging To Determine Molar Concentrations of Isolated Carbon Nanotube Species.

    PubMed

    Galassi, Thomas V; Jena, Prakrit V; Roxbury, Daniel; Heller, Daniel A

    2017-01-17

    Electronic and biological applications of carbon nanotubes can be highly dependent on the species (chirality) of nanotube, purity, and concentration. Existing bulk methods, such as absorbance spectroscopy, can quantify sp(2) carbon based on spectral bands, but nanotube length distribution, defects, and carbonaceous impurities can complicate quantification of individual particles. We present a general method to relate the optical density of a photoluminescent nanotube sample to the number of individual nanotubes. By acquiring 3-dimensional images of nanotubes embedded in a gel matrix with a reducing environment, we quantified all emissive nanotubes in a volume. Via spectral imaging, we assessed structural impurities and precisely determined molar concentrations of the (8,6) and (9,4) nanotube species. We developed an approach to obtain the molarity of any structurally enriched semiconducting single-walled carbon nanotube preparation on a per-nanotube basis.

  7. Determinants of bone and blood lead concentrations in the early postpartum period

    PubMed Central

    Brown, M. J.; Hu, H.; Gonzales-Cossio, T.; Peterson, K.; Sanin, L.; Kageyama, M. d.; Palazuelos, E.; Aro, A.; Schnaas, L.; Hernandez-Avila, M.

    2000-01-01

    OBJECTIVE—This study investigated determinants of bone and blood lead concentrations in 430 lactating Mexican women during the early postpartum period and the contribution of bone lead to blood lead.
METHODS—Maternal venous lead was measured at delivery and postpartum, and bone lead concentrations, measured with in vivo K-x ray fluorescence, were measured post partum. Data on environmental exposure, demographic characteristics, and maternal factors related to exposure to lead were collected by questionnaire. Linear regression was used to examine the relations between bone and blood lead, demographics, and environmental exposure variables.
RESULTS—Mean (SD) blood, tibial, and patellar lead concentrations were 9.5 (4.5) µg/dl, 10.2 (10.1) µg Pb/g bone mineral, and 15.2 (15.1) µg Pb/g bone mineral respectively. These values are considerably higher than values for women in the United States. Older age, the cumulative use of lead glazed pottery, and higher proportion of life spent in Mexico City were powerful predictors of higher bone lead concentrations. Use of lead glazed ceramics to cook food in the past week and increased patellar lead concentrations were significant predictors of increased blood lead. Patellar lead concentrations explained one third of the variance accounted for by the final blood lead model. Women in the 90th percentile for patella lead had an untransformed predicted mean blood lead concentration 3.6 µg/dl higher than those in the 10th percentile.
CONCLUSIONS—This study identified the use of lead glazed ceramics as a major source of cumulative exposure to lead, as reflected by bone lead concentrations, as well as current exposure, reflected by blood lead, in Mexico. A higher proportion of life spent in Mexico City, a proxy for exposure to leaded gasoline emissions, was identified as the other major source of cumulative lead exposure. The influence of bone lead on blood lead coupled with the long half life of lead in bone has

  8. Determination of radon and radium concentrations in drinking water samples around the city of Kutahya.

    PubMed

    Sahin, Latife; Cetinkaya, Hakan; Murat Saç, Müslim; Içhedef, Mutlu

    2013-08-01

    The concentration of radium and radon has been determined in drinking water samples collected from various locations of Kutahya city, Turkey. The water samples are taken from public water sources and tap water, with the collector chamber method used to measure the radon and radium concentration. The radon concentration ranges between 0.1 and 48.6±1.7 Bq l(-1), while the radium concentration varies from a minimum detectable activity of <0.02-0.7±0.2 Bq l(-1) in Kutahya city. In addition to the radon and radium levels, parameters such as pH, conductivity and temperature of the water, humidity, pressure, elevation and the coordinates of the sampling points have also been measured and recorded. The annual effective dose from radon and radium due to typical water usage has been calculated. The resulting contribution to the annual effective dose due to radon ingestion varies between 0.3 and 124.2 μSv y(-1); the contribution to the annual effective dose due to radium ingestion varies between 0 and 143.3 μSv y(-1); the dose contribution to the stomach due to radon ingestion varies between 0.03 and 14.9 μSv y(-1). The dose contribution due to radon inhalation ranges between 0.3 and 122.5 μSv y(-1), assuming a typical transfer of radon in water to the air. For the overwhelming majority of the Kutahya population, it is determined that the average radiation exposure from drinking water is less than 73.6 µSv y(-1).

  9. 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

  10. 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.

  11. Interlaboratory study of immunochromatography for the rapid determination of cadmium concentrations in cereals and soybeans.

    PubMed

    Abe, Kaoru; Nakamura, Katsuo; Naito, Shigehiro

    2014-01-01

    Cadmium (Cd) is one of the most toxic heavy metals to humans. To prevent the distribution of Cd-contaminated food, a simple and quick on-site test for measuring Cd concentrations in agricultural products is needed. Recently, an immunochromatography kit developed for determining Cd in rice was reported to be useful for determining Cd in many other crops. We conducted an interlaboratory study to evaluate the kit for determining Cd in cereals (wheat and rice) and soybeans. Ten test materials were used, and 12 test samples including two sets of blind duplicates were distributed to 12 laboratories in Japan. The Cd recoveries (relative to certified values or values determined by inductively coupled plasma-MS) from all test materials were 84.6-125.1%. Repeatability RSD values of the test materials ranged from 8.8 to 14.8%. Reproducibility RSD values ranged from 13.4 to 27.6%, averaging 21.3%. The Horwitz ratio ranged from 0.61 to 1.36. The reproducibility was within the range of ELISA results for measuring toxins and allergens in food. Our results indicated that the kit was an inexpensive, reliable tool for quick and easy on-site determination of Cd in cereals and soybeans.

  12. Determination of chlorine concentration using single temperature modulated semiconductor gas sensor

    NASA Astrophysics Data System (ADS)

    Woźniak, Ł.; Kalinowski, P.; Jasiński, G.; Jasiński, P.

    2016-11-01

    A periodic temperature modulation using sinusoidal heater voltage was applied to a commercial SnO2 semiconductor gas sensor. Resulting resistance response of the sensor was analyzed using a feature extraction method based on Fast Fourier Transformation (FFT). The amplitudes of the higher harmonics of the FFT from the dynamic nonlinear responses of measured gas were further utilized as an input for Artificial Neuron Network (ANN). Determination of the concentration of chlorine was performed. Moreover, this work evaluates the sensor performance upon sinusoidal temperature modulation.

  13. Determination of certain trace impurities in uranium concentrates by activation analysis.

    PubMed

    Abdel-Rassoul, A A; Wahba, S S; Abdel-Aziz, A

    1966-03-01

    A method is presented for the simultaneous determination of chromium, iron, cobalt and zinc in samples of uranium concentrates, oxides and metallic uranium by neutron-activation analysis. The method involves adequate decontamination of gross fission product activities by adsorption on silica gel, removal of uranium by solvent extraction, separation of most carrier-free rare-earth activities by coprecipitation with aluminium chloride, and, finally, fractional separation of the elements concerned by ion-exchange chromatography. The method can assay ppm of such elements in limited quantities of samples by scintillation gamma-ray spectrometric analysis with a reproducibility of 10-15%.

  14. 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.

  15. [Rapid determination of serum iron concentration using bathophenanthroline sulfonate in a formate buffered system].

    PubMed

    Pré, J; Benlatrèche, C

    1977-03-01

    A simple accurate and very reproducible procedure for measuring serum iron concentration without precipitating serum proteins is described. In the same time, iron is released from serum transferrin, reduced and determined at 535 mn by incubation in a water bath at 55 degrees for five minutes within a formate buffered system (pH 2,6; i = 0,05) including bathophenanthroline sulfonate. This method yields values very similar to those obtained by that of the International Committee for Standardization in Hematology (ICSH).

  16. [Isolation, extractive concentration, and determination of caffeine in the studies of blood plasma].

    PubMed

    Korenman, Ia I; Shormanov, V K; Mokshina, N Ia; Krivosheeva, O A; Golubitskiĭ, G B

    2012-01-01

    The optimal conditions for the isolation of caffeine from human blood by means of acetone extraction are described with special reference to the peculiarities of extraction from aqueous solutions. The possibility of concentration and purification of caffeine from blood plasma using acetone and aceton-chlorophorm mixture (2:8) as the solvents is illustrated. In addition, purification by silica-gel thin layer chromatography is discussed. Thin layer chromatography, UV-spectrophotometry, and high performance liquid chromatography are considered as potential methods for the identification and quantitative determination of caffeine.

  17. Interaction of exposure concentration and duration in determining acute toxic effects of sarin vapor in rats.

    PubMed

    Mioduszewski, R; Manthei, J; Way, R; Burnett, D; Gaviola, B; Muse, W; Thomson, S; Sommerville, D; Crosier, R

    2002-04-01

    Sarin (GB) vapor exposure is associated with both systemic and local toxic effects occurring primarily via the inhalation and ocular routes. The objective of these studies was to develop models for predicting dose-response effects of GB vapor concentrations as a function of exposure duration. Thus, the probability of GB vapor-induced lethality was estimated in rats exposed to various combinations of exposure concentration and duration. Groups of male and female Sprague-Dawley rats were exposed to one of a series of GB vapor concentrations for a single duration (5-360 min) in a whole-body dynamic chamber. The onset of clinical signs and changes in blood cholinesterase activity were measured with each exposure. Separate effective concentrations for lethality in 50% of the exposed population (LC50) and corresponding dose-response slopes were determined for each exposure duration by the Bliss probit method. Contrary to that predicted by Haber's rule, the interaction of LC50 x time (LCT50) values increased with exposure duration (i.e., the CT for 50% lethality in the exposed population and corresponding dose-response slope was not constant over time). A plot of log (LCT50) versus log (exposure time) showed significant curvature. Predictive models derived from multifactor probit analysis of results describing the relationship between exposure conditions and probability of lethality in the rat are discussed. Overall, female rats were more sensitive to GB vapor toxicity than male rats over the range of exposure concentration and duration studied. Miosis was the initial clinical sign noted after the start of GB vapor exposure. Although blood cholinesterase activity was significantly inhibited by GB vapor exposure, poor correlation between cholinesterase inhibition and exposure conditions or cholinesterase inhibition and severity of clinical signs was noted.

  18. 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)

  19. 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…

  20. 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.

  1. 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.

  2. Determining optimum service conditions for concentrator mirrors by methods of mathematically planned experiment

    NASA Astrophysics Data System (ADS)

    Ismanzhanov, A.; Altman, T. M.; Zakhidov, R. A.; Dubrovskiy, L. A.

    1984-02-01

    A method of mathematically planning an experiment was proposed for determining the optimum service conditions for concentrator mirrors and also obtaining data on mirror performance which can be useful for optimization of the mirror manufacturing technology. First are determined the number of factors influencing a mirror under service conditions and the ranges of their likely variation. Then, by an a priori ranking process and on the basis of preliminary analysis, these factors are classified into significant and insignificant ones in terms of their contribution to the aging process. The method was applied to aluminum mirrors with front side reflection and various protective coatings. The plan of a 4 factor (air humidity, abrasive wear by dust and sand, photochemical action of solar radiation, mechanical action of cleaning agent) 3 level (base, upper, lower) experiment is shown and the regression equation is obtained for a typical case. Recommendations on optimum mirror design and selection are made on the basis of this experiment.

  3. 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.

  4. Correlation between linezolid zone diameter and minimum inhibitory concentration values determined by regression analysis.

    PubMed

    Dimitriu, G; Poiata, Antonia; Tuchiluş, Cristina; Buiuc, D

    2006-01-01

    Linezolid is a new synthetic antibiotic belonging to the oxazolidinone class, available for the therapy of gram-positive infections, caused by methicillin-resistant staphylococci, vancomycin-resistant enterococci and penicillin-resistant pneumococci. The aim of the study was to determine the in vitro activity of linezolid against staphylococci strains and also to determine the relationship between the minimum inhibitory concentration (MIC) and inhibition zone diameter by calculating the regression analysis. We tested one hundred S. aureus isolates, obtained from healthy persons (naso-pharyngeal swabs) during 2005 year. The antibiotic susceptibility of strains was determined by disk diffusion standardized method and by agar dilution method using a multipoint inoculator. The relationship between the diameter of the inhibition zone produced by a linezolid disc impregnated with a fixed amount (30 eg) was determined by regression performed with the least squares method, considering the log2 of the minimum inhibitory concentrations (MICs) as the independent variable and the zone diameter as the dependent variable. The MIC values expressed in logarithmic form are plotted against inhibition zone diameter (arithmetic scale) of the same strain. The activity of linezolid against staphylococci was very good, with MIC 90 of 1 mg/l. All strains were fully sensitive. The regression line for linezolid passes through a continuous series of points that all are approximately located on the a straight line. For each of the MIC values the differences result no greater than 23 mm in diameter sizes were registered. Regression equation was y= -0.188x + 8.048. In conclusion, the regression line analysis calculated for linezolid, demonstrates a significant correlation between MIC values and the inhibition zone diameters obtained by a 30 mg disc.

  5. Precise determination of the absolute isotopic abundance ratio and the atomic weight of chlorine in three international reference materials by the positive thermal ionization mass spectrometer-Cs2Cl+-graphite method.

    PubMed

    Wei, Hai-Zhen; Jiang, Shao-Yong; Xiao, Ying-Kai; Wang, Jun; Lu, Hai; Wu, Bin; Wu, He-Pin; Li, Qing; Luo, Chong-Guang

    2012-12-04

    Because the variation in chlorine isotopic abundances of naturally occurring chlorine bearing substances is significant, the IUPAC Inorganic Chemistry Division, Commission on Isotopic Abundances and Atomic Weights (CIAAW-IUPAC) decided that the uncertainty of atomic weight of chlorine (A(r)(Cl)) should be increased so that the implied range was related to terrestrial variability in 1999 (Coplen, T. B. Atomic weights of the elements 1999 (IUPAC Technical Report), Pure Appl. Chem.2001, 73(4), 667-683; and then, it emphasized that the standard atomic weights of ten elements including chlorine were not constants of nature but depend upon the physical, chemical, and nuclear history of the materials in 2009 (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396). According to the agreement by CIAAW that an atomic weight could be defined for one specified sample of terrestrial origin (Wieser, M. E.; Coplen, T. B. Pure Appl. Chem.2011, 83(2), 359-396), the absolute isotope ratios and atomic weight of chlorine in standard reference materials (NIST 975, NIST 975a, ISL 354) were accurately determined using the high-precision positive thermal ionization mass spectrometer (PTIMS)-Cs(2)Cl(+)-graphite method. After eliminating the weighing error caused from evaporation by designing a special weighing container and accurately determining the chlorine contents in two highly enriched Na(37)Cl and Na(35)Cl salts by the current constant coulometric titration, one series of gravimetric synthetic mixtures prepared from two highly enriched Na(37)Cl and Na(35)Cl salts was used to calibrate two thermal ionization mass spectrometers in two individual laboratories. The correction factors (i.e., K(37/35) = R(37/35meas)/R(37/35calc)) were obtained from five cycles of iterative calculations on the basis of calculated and determined R((37)Cl/(35)Cl) values in gravimetric synthetic mixtures. The absolute R((37)Cl/(35)Cl) ratios for NIST SRM 975, NIST 975a, and ISL 354 by the precise

  6. A colorimetric method for the determination of carboxyhaemoglobin over a wide range of concentrations

    PubMed Central

    Trinder, P.; Harper, F. E.

    1962-01-01

    A colorimetric technique for the determination of carboxyhaemoglobin in blood is described. Carbon monoxide released from blood in a standard Conway unit reacts with palladous chloride/arsenomolybdate solution to produce a blue colour. Using 0·5 to 2 ml. of blood, the method will estimate carboxyhaemoglobin accurately at levels from 0·1% to 100% of total haemoglobin and in the presence of other abnormal pigments. A number of methods are available for the determination of carboxyhaemoglobin; none is accurate below a concentration of 1·5 g. carboxyhaemoglobin per 100 ml. but for most clinical purposes this is not important. For forensic purposes and occasionally in clinical use, an accurate determination of carboxyhaemoglobin below 750 mg. per 100 ml. may be required and no really satisfactory method is at present available. Some time ago when it was important to know whether a person who was found dead in a burning house had died before or after the fire had started, we became interested in developing a method which would determine accurately carboxyhaemoglobin at levels of 750 mg. per 100 ml. PMID:13922505

  7. Determinants of Anemia and Hemoglobin Concentration in Haitian School-Aged Children

    PubMed Central

    Iannotti, Lora L.; Delnatus, Jacques R.; Odom, Audrey R.; Eaton, Jacob C.; Griggs, Jennifer J.; Brown, Sarah; Wolff, Patricia B.

    2015-01-01

    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

  8. Methods for determining agent concentration profiles in agarose gel during convection-enhanced delivery.

    PubMed

    Sindhwani, Nikhil; Ivanchenko, Oleksandr; Lueshen, Eric; Prem, Komal; Linninger, Andreas A

    2011-03-01

    Convection-enhanced delivery (CED) is a promising technique to deliver large molecular weight drugs to the human brain for treatment of Parkinson's, Alzheimer's, or brain tumors. Researchers have used agarose gels to study mechanisms of agent transport in soft tissues like brain due to its similar mechanical and transport properties. However, inexpensive quantitative techniques to precisely measure achieved agent distribution in agarose gel phantoms during CED are missing. Such precise measurements of concentration distribution are needed to optimize drug delivery. An optical experimental method to accurately quantify agent concentration in agarose is presented. A novel geometry correction algorithm is used to determine real concentrations from observable light intensities captured by a digital camera. We demonstrate the technique in dye infusion experiments that provide cylindrical and spherical distributions when infusing with porous membrane and conventional single-port catheters, respectively. This optical method incorporates important parameters, such as optimum camera exposure, captured camera intensity calibration, and use of collimated light source for maximum precision. We compare experimental results with numerical solutions to the convection diffusion equation. The solutions of convection-diffusion equations in the cylindrical and spherical domains were found to match the experimental data obtained by geometry correction algorithm.

  9. Estimation of thickness of concentration boundary layers by osmotic volume flux determination.

    PubMed

    Jasik-Ślęzak, Jolanta S; Olszówka, Kornelia M; Slęzak, Andrzej

    2011-06-01

    The estimation method of the concentration boundary layers thicknesses (δ) in a single-membrane system containing non-electrolytic binary or ternary solutions was devised using the Kedem-Katchalsky formalism. A square equation used in this method contains membrane transport (L(p), σ, ω) and solution (D, C) parameters as well as a volume osmotic flux (J(v)). These values can be determined in a series of independent experiments. Calculated values δ are nonlinearly dependent on the concentrations of investigated solutions and the membrane system configuration. These nonlinearities are the effect of a competition between spontaneously occurring diffusion and natural convection. The mathematical model based on Kedem-Katchalsky equations and a concentration Rayleigh number (R(C)) was presented. On the basis of this model we introduce the dimensionless parameter, called by us a Katchalsky number (Ka), modifies R(C) of membrane transport. The critical value of this number well describes a moment of transition from the state of diffusion into convective diffusion membrane transport.

  10. Quantitative kinetics of proteolytic enzymes determined by a surface concentration-based assay using peptide arrays.

    PubMed

    Jung, Se-Hui; Kong, Deok-Hoon; Park, Seoung-Woo; Kim, Young-Myeong; Ha, Kwon-Soo

    2012-08-21

    Peptide arrays have emerged as a key technology for drug discovery, diagnosis, and cell biology. Despite the promise of these arrays, applications of peptide arrays to quantitative analysis of enzyme kinetics have been limited due to the difficulty in obtaining quantitative information of enzymatic reaction products. In this study, we developed a new approach for the quantitative kinetics analysis of proteases using fluorescence-conjugated peptide arrays, a surface concentration-based assay with solid-phase peptide standards using dry-off measurements, and compared it with an applied concentration-based assay. For fabrication of the peptide arrays, substrate peptides of cMMP-3, caspase-3, caspase-9, and calpain-1 were functionalized with TAMRA and cysteine, and were immobilized onto amine-functionalized arrays using a heterobifunctional linker, N-[γ-maleimidobutyloxy]succinimide ester. The proteolytic activities of the four enzymes were quantitatively analyzed by calculating changes induced by enzymatic reactions in the concentrations of peptides bound to array surfaces. In addition, this assay was successfully applied for calculating the Michaelis constant (K(m,surf)) for the four enzymes. Thus, this new assay has a strong potential for use in the quantitative evaluation of proteases, and for drug discovery through kinetics studies including the determination of K(m) and V(max).

  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. Cyanide concentrations in blood after cigarette smoking, as determined by a sensitive fluorimetric method.

    PubMed

    Lundquist, P; Rosling, H; Sörbo, B; Tibbling, L

    1987-07-01

    Using the sensitive fluorimetric method described here, we evaluated the determination of blood cyanide as a method for monitoring exposure to tobacco smoke. The mean concentration of cyanide in blood from eight nonsmokers was 0.098 (SD 0.036) mumol/L. The concentration of cyanide in blood of smokers who had refrained from smoking for at least 2 h before sampling peaked immediately after the subjects smoked a cigarette, then rapidly declined, with a half-life of about 4 min. Its rapid disappearance from blood makes cyanide an unsuitable marker of exposure to tobacco smoke. Because the ability of patients with hepatic dysfunction to detoxify cyanide has been presumed to be impaired, we monitored the concentrations of cyanide in the blood of four patients with severe hepatic insufficiency who smoked a cigarette. The rate of elimination of cyanide from blood after smoking was only slightly less in these patients than in the controls, and the difference was not statistically significant.

  13. Sequence-specific determination of protein and peptide concentrations by absorbance at 205 nm.

    PubMed

    Anthis, Nicholas J; Clore, G Marius

    2013-06-01

    Quantitative studies in molecular and structural biology generally require accurate and precise determination of protein concentrations, preferably via a method that is both quick and straightforward to perform. The measurement of ultraviolet absorbance at 280 nm has proven especially useful, since the molar absorptivity (extinction coefficient) at 280 nm can be predicted directly from a protein sequence. This method, however, is only applicable to proteins that contain tryptophan or tyrosine residues. Absorbance at 205 nm, among other wavelengths, has been used as an alternative, although generally using absorptivity values that have to be uniquely calibrated for each protein, or otherwise only roughly estimated. Here, we propose and validate a method for predicting the molar absorptivity of a protein or peptide at 205 nm directly from its amino acid sequence, allowing one to accurately determine the concentrations of proteins that do not contain tyrosine or tryptophan residues. This method is simple to implement, requires no calibration, and should be suitable for a wide range of proteins and peptides.

  14. Determination of molybdenum (VI) in sea water with preliminary concentration by the method of ion flotation

    SciTech Connect

    Andreeva, I. Yu.; Drapchinskaya, O.L.; Lebedeva, L.I.

    1985-10-01

    The purpose of this paper is to assess the feasibility of using the method of ion flotation for the concentration of microamounts of molybdenum (VI) during determination in sea water. The ion flotation method is used for the purification of industrial sewage from the ions of nonferrous metals, including molybdenum (VI) with its content of up to 50 mg/liter. A 1.10/sup -4/M solution of sodium molybdate in 0.1M NaOH was used. The effect of different factors on the ion flotation process of molybdenum (VI) was investigated: pH of the solution, flotation times, concentrations of surface-active substances (SAS), molybdenum (IV), extraneous salts. Data presented show that the ion flotation method in conjunction with the photometric method of determining molybdenum with brompyrogallol red (BPR) and cetylpridinium chloride (CP) (limit of detection 0.02 micrograms/liter) allows the content of molybdenum (VI) in sea water to be established with sufficient reliability and reproducibility.

  15. The measurement of thermal neutron flux depression for determining the concentration of boron in blood.

    PubMed

    Brooke, S L; Green, S; Charles, M W; Beddoe, A H

    2001-03-01

    Boron neutron capture therapy (BNCT) is a form of targeted radiotherapy that relies on the uptake of the capture element boron by the volume to be treated. The treatment procedure requires the measurement of boron in the patient's blood. The investigation of a simple and inexpensive method for determining the concentration of the capture element 10B in blood is described here. This method, neutron flux depression measurement, involves the determination of the flux depression of thermal neutrons as they pass through a boron-containing sample. It is shown via Monte Carlo calculations and experimental verification that, for a maximum count rate of 1 x 10(4) counts/s measured by the detector, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 32 +/- 2 min. For a source activity of less than 1.11 x 10(11) Bq and a maximum count rate of less than 1 x 10(4) counts/s, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 58 +/- 3 min. It has also been shown that this technique can be applied to the measurement of the concentration of any element with a high thermal neutron cross section such as 157Gd.

  16. 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.

  17. Acrylamide concentration determines the direction and magnitude of helical membrane protein gel shifts

    PubMed Central

    Rath, Arianna; Cunningham, Fiona; Deber, Charles M.

    2013-01-01

    SDS/PAGE is universally used in biochemistry, cell biology, and immunology to resolve minute protein amounts readily from tissue and cell extracts. Although molecular weights of water-soluble proteins are reliably determined from their SDS/PAGE mobility, most helical membrane proteins, which comprise 20–30% of the human genome and the majority of drug targets, migrate to positions that have for decades been unpredictably slower or faster than their actual formula weight, often confounding their identification. Using de novo designed transmembrane-mimetic polypeptides that match the composition of helical membrane-spanning sequences, we quantitate anomalous SDS/PAGE fractionation of helical membrane proteins by comparing the relative mobilities of these polypeptides with typical water-soluble reference proteins on Laemmli gels. We find that both the net charge and effective molecular size of the migrating particles of transmembrane-mimetic species exceed those of the corresponding reference proteins and that gel acrylamide concentration dictates the impact of these two factors on the direction and magnitude of anomalous migration. Algorithms we derived from these data compensate for this differential effect of acrylamide concentration on the SDS/PAGE mobility of a variety of natural membrane proteins. Our results provide a unique means to predict anomalous migration of membrane proteins, thereby facilitating straightforward determination of their molecular weights via SDS/PAGE. PMID:24019476

  18. Development of a Direct Spectrophotometric and Chemometric Method for Determining Food Dye Concentrations.

    PubMed

    Arroz, Erin; Jordan, Michael; Dumancas, Gerard G

    2017-01-01

    An ultraviolet visible (UV-Vis) spectrophotometric and partial least squares (PLS) chemometric method was developed for the simultaneous determination of erythrosine B (red), Brilliant Blue, and tartrazine (yellow) dyes. A training set (n = 64) was generated using a full factorial design and its accuracy was tested in a test set (n = 13) using a Box-Behnken design. The test set garnered a root mean square error (RMSE) of 1.79 × 10(-7) for blue, 4.59 × 10(-7) for red, and 1.13 × 10(-6) for yellow dyes. The relatively small RMSE suggests only a small difference between predicted versus measured concentrations, demonstrating the accuracy of our model. The relative error of prediction (REP) for the test set were 11.73%, 19.52%, 19.38%, for blue, red, and yellow dyes, respectively. A comparable overlay between the actual candy samples and their replicated synthetic spectra were also obtained indicating the model as a potentially accurate method for determining concentrations of dyes in food samples.

  19. Alternative determination of blood alcohol concentration by (1)H NMR spectroscopy.

    PubMed

    Zailer, Elina; Diehl, Bernd W K

    2016-02-05

    A rapid, accurate and specific proton nuclear magnetic resonance ((1)H NMR) spectroscopic method is developed to determine ethanol in blood, known as the blood alcohol concentration (BAC). The limits of detection and quantification are 0.02g/L and 0.07g/L, respectively. The (1)H NMR spectra show linearity for whole blood and serum samples of a concentration range of 0.00-3.00g/L (R(2)>0.9995). The (1)H NMR method is applied and validated for whole blood as the sample media. Real driving under influence case samples are analyzed with the reference enzyme-based alcohol dehydrogenase and headspace gas chromatography techniques by the Forensic Medicine in Bonn. The reference results are compared with the (1)H NMR spectroscopic results. The validation and comparison indicate that (1)H NMR is suitable for the quantification of BAC in whole blood. This technique has the advantages of automated analysis with good measurement precision and fast sample throughput. A drop of blood (V=20μL) is adequate for an analysis leading to a possible simplification of the sample collection. Due to the non-destructive method, follow-up examinations by (1)H NMR spectroscopy or DNA determinations by different techniques (PCR, in situ hybridization) are possible in resolving legal disputes.

  20. Determination of the silicon concentration in plant material using Tiron extraction.

    PubMed

    Guntzer, F; Keller, C; Meunier, J D

    2010-11-01

    • The quantification of silicon (Si) in plants generally requires a digestion procedure before the determination of the dissolved Si concentration by spectrometric analysis. Recent procedures produce rapid and accurate measurements, but are based on either hazardous chemicals or sophisticated instrumentation. • Here, we describe a simpler procedure using Tiron. Tiron [4,5-dihydroxy-1,3-benzene-disulfonic acid disodium salt, (HO)(2)C(6)H(2)(SO(3)Na)(2)] is currently used as a selective extractant for amorphous silica in soils. Because Si in the shoots is mostly composed of amorphous opaline silica particles (i.e. phytoliths), we tested the Tiron extraction procedure for plants. • Our results are critically discussed in relation to two other standard procedures: electrothermal vaporization determination and high-temperature lithium-metaborate digestion. • We demonstrate that Tiron extraction is an alternative method which allows the rapid, safe and accurate quantification of Si in shoots of various plants covering a wide range of Si concentrations.

  1. Nanoparticle Tracking Analysis for Determination of Hydrodynamic Diameter, Concentration, and Zeta-Potential of Polyplex Nanoparticles.

    PubMed

    Wilson, David R; Green, Jordan J

    2017-01-01

    Nanoparticle tracking analysis (NTA) is a recently developed nanoparticle characterization technique that offers certain advantages over dynamic light scattering for characterizing polyplex nanoparticles in particular. Dynamic light scattering results in intensity-weighted average measurements of nanoparticle characteristics. In contrast, NTA directly tracks individual particles, enabling concentration measurements as well as the direct determination of number-weighted particle size and zeta-potential. A direct number-weighted assessment of nanoparticle characteristics is particularly useful for polydisperse samples of particles, including many varieties of gene delivery particles that can be prone to aggregation. Here, we describe the synthesis of poly(beta-amino ester)/deoxyribonucleic acid (PBAE/DNA) polyplex nanoparticles and their characterization using NTA to determine hydrodynamic diameter, zeta-potential, and concentration. Additionally, we detail methods of labeling nucleic acids with fluorophores to assess only those polyplex nanoparticles containing plasmids via NTA. Polymeric gene delivery of exogenous plasmid DNA has great potential for treating a wide variety of diseases by inducing cells to express a gene of interest.

  2. 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

  3. Methodology for the determination of normal background concentrations of contaminants in English soil.

    PubMed

    Ander, E Louise; Johnson, Christopher C; Cave, Mark R; Palumbo-Roe, Barbara; Nathanail, C Paul; Lark, R Murray

    2013-06-01

    The revised Environmental Protection Act Part 2A contaminated land Statutory Guidance (England and Wales) makes reference to 'normal' levels of contaminants in soil. The British Geological Survey has been commissioned by the United Kingdom Department for Environment, Food and Rural Affairs (Defra) to estimate contaminant levels in soil and to define what is meant by 'normal' for English soil. The Guidance states that 'normal' levels of contaminants are typical and widespread and arise from a combination of both natural and diffuse pollution contributions. Available systematically collected soil data sets for England are explored for inorganic contaminants (As, Cd, Cu, Hg, Ni and Pb) and benzo[a]pyrene (BaP). Spatial variability of contaminants is studied in the context of the underlying parent material, metalliferous mineralisation and associated mining activities, and the built (urban) environment, the latter being indicative of human activities such as industry and transportation. The most significant areas of elevated contaminant concentrations are identified as contaminant domains. Therefore, rather than estimating a single national contaminant range of concentrations, we assign an upper threshold value to contaminant domains. Our representation of this threshold is a Normal Background Concentration (NBC) defined as the upper 95% confidence limit of the 95th percentile for the soil results associated with a particular domain. Concentrations of a contaminant are considered to be typical and widespread for the identified contaminant domain up to (and including) the calculated NBC. A robust statistical methodology for determining NBCs is presented using inspection of data distribution plots and skewness testing, followed by an appropriate data transformation in order to reduce the effects of point source contamination.

  4. 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.

  5. 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...

  6. Determination of cyanide and nitrate concentrations in drinking, irrigation, and wastewaters

    PubMed Central

    Mousavi, Seyed Reza; Balali-Mood, Mahdi; Riahi-Zanjani, Bamdad; Sadeghi, Mahmood

    2013-01-01

    Background: The chemical contamination of water is a major concern for the environmental and health authorities globally. Some anions present in the water are required for human health, but some of them are harmful. Free cyanide and nitrate are amongst the toxic agents in the aquatic environment. Cyanide is highly toxic for human beings. Industrial plants could be attributed to a major source of these toxic agents. Therefore, cyanide and nitrate concentrations in the drinking and irrigation water wells in the high industrial plants were evaluated. Materials and Methods: The samples (57) were taken from drinking and irrigation water wells as well as from a wastewater refinery in north of Mashhad in three stages – March 2009, June 2010, and July 2010. Determination of cyanide and nitrate were performed by a spectrophotometer using commercially available kits according to the manufacturer's protocols. Results: Cyanide and nitrate concentrations in the drinking water samples of the three stages were 0.0050 ± 0.0007, 0.0070 ± 0.0018, 0.0008 ± 0.0014 mg/L and 6.50 ± 2.80, 7.20 ± 1.80, 7.50 ± 1.90 mg/L, respectively. Cyanide mean concentration during March, June, and July was significant (P = 0.001), whereas nitrate mean concentration was not (P = 0.5). Cyanide and nitrate concentrations in the irrigation water samples of the three stages were 0.0140 ± 0.0130, 0.0077 ± 0.0025, 0.0087 ± 0.0047 mg/L and 12.37 ± 8.12, 8.04 ± 3.99, 8.40 ± 2.60 mg/L, respectively. Cyanide (P = 0.754) and nitrate (P = 0.705) concentrations were not significant during three occasions. Cyanide and nitrate concentrations in the wastewaters of the three stages were 0.1020 ± 0.033, 0.1180 ± 0.033, 0.1200 ± 0.035 mg/L and 1633.80 ± 40.74, 279.00 ± 152.17, 298.40 ± 304.74 mg/L, respectively. Cyanide (P = 0.731) and nitrate (P = 0.187) concentration in wastewaters were not significant during different months. Conclusion: Although nitrate and cyanide concentrations in the drinking

  7. Evaluation of capillary electrophoresis for determining the concentration of dissolved silica in geothermal brines.

    PubMed

    Santoyo, E; García, R; Aparicio, A; Verma, Surendra P; Verma, M P

    2005-04-15

    The determination of silica concentrations in geothermal brines is widely recognized as a difficult analytical task due to its complex chemical polymerization kinetics that occurs during sample collection and chemical analysis. Capillary electrophoresis (CE) has been evaluated as a new reliable analytical method to measure silica (as silicates) in geothermal brines. Synthetic and geothermal brine samples were used to evaluate CE methodology. A capillary electrophoresis instrument, Quanta 4000 (Waters-Millipore) coupled with a Waters 820 workstation was used to carry out the experimental work. The separation of silicates was completed in approximately 5.5 min using a conventional fused-silica capillary (75 microm i.d. x 375 microm o.d. x 60 cm total length). A hydrostatic injection (10 cm for 20 s at 25 degrees C) was employed for introducing the samples. The carrier electrolyte consisted of 10 mM sodium chromate, 3 mM tetradecyltrimethyl-ammonium hydroxide (TTAOH), 2 mM sodium carbonate, and 1 mM sodium hydroxide, adjusted to a pH 11.0 +/- 0.1. Silicates were determined using an indirect UV detection at a wavelength of 254 nm with a mercury lamp and with a negative power supply (-15 kV). A good reproducibility in the migration times (%R.S.D. approximately 1.6%) based on six non-consecutive injections of synthetic brine solutions was obtained. A linear response between silica concentration and corrected peak area was observed. Ordinary (OLR) and weighted (WLR) linear regression models were used for calculating silica concentrations in all samples using the corresponding fitted calibration curves. The analytical results of CE were finally compared with the most probable values of synthetic reference standards of silica using the Student's t-test. No significant differences were found between them at P = 0.01. Similarly, the atomic absorption spectrometry (AAS) results were also compared with the most probable concentrations of the same reference standards, finding

  8. Determining non-linear characteristics of a concentrating solar collector according to the experiment design

    NASA Astrophysics Data System (ADS)

    Nemś, M.; Kasperski, J.

    2016-09-01

    A linear concentrating solar air collector with internal multiple-fin array was built. The collector was designed as an air heater for the system of house heating with an all-year-round heat accumulation. In order to conduct transient type numerical simulations of the yearlong work cycle of the system, it was necessary to know the working characteristic of the solar collector. To determine the characteristics, some factors for experimental research were selected. The authors decided to conduct experimental research on the basis of fractional 3k factorial design for three factors. A set-up was built and then, a series of experiments were conducted according to the adopted experiment design. A working characteristic in the form of a quadratic polynomial was determined, and a diagram was prepared. The obtained results were then discussed. The obtained research method and the determined formula met the needs of further numerical modelling of the year-long work of the heating system containing the examined solar collector.

  9. A role for anthocyanin in determining wine tannin concentration in Shiraz.

    PubMed

    Kilmister, Rachel L; Mazza, Marica; Baker, Nardia K; Faulkner, Peta; Downey, Mark O

    2014-01-01

    Four wines were made to investigate the effect of different anthocyanin and tannin fruit concentrations on wine phenolics and colour. Wines that were made from fruit with high anthocyanin concentration had high tannin concentrations regardless of the concentration of tannin in fruit, while wines made from fruit with low anthocyanin also had low tannin concentration. It was found that fruit anthocyanin concentration correlated with wine tannin concentration, wine colour and polymeric pigment formation. Anthocyanin concentration might be a key component for increasing tannin solubility and extraction into wine and the formation of polymeric pigments. Industry implications include managing tannin and anthocyanin fruit concentration for targeting tannin extraction and polymeric pigment formation in wine.

  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. Determination of density and concentration from fluorescent images of a gas flow

    NASA Astrophysics Data System (ADS)

    Belan, Marco; de Ponte, Sergio; Tordella, Daniela

    2008-09-01

    A fluorescence image analysis procedure to determine the distribution of species concentration and density in a gas flow is proposed. The fluorescent emission is due to the excitation of atoms/molecules of a gas that is intercepted by an electron sheet. The intensity of the fluorescent light is proportional to the local number density of the gas. When the gas flow is a mixture of different species, this proportionality can be used to extract the contribution associated with the species from the spectral superposition acquired by a digital camera. In particular, the fact is exploited such that the ratio between a pair of color intensities takes different values for different gases and that different linear superpositions of different color intensities yield a ratio that varies with the species concentration. This leads to a method that simultaneously reveals species concentrations and mass density of the mixture. For the proper working of a continuous electron gun in a gas, the procedure can be applied to gas flow where the pressure is below the thresholds of 200˜300 Pa and the number density is no greater than 1023 m-3. To maintain the constancy of the emission coefficients, the temperature variation in the flow should be inside the range 75-900 K (above the temperature where the probability to meet disequilibrium phenomena due to rarefaction is low, below the temperature where visible thermal emission is present). The overall accuracy of the measurement method is approximately 10%. The uncertainty can vary locally in the range from 5 to 15% for the concentration and from 5 to 20% for the density depending on the local signal-to-noise ratio. The procedure is applied to two under-expanded sonic jets discharged into a different gas ambient—Helium into Argon and Argon into Helium—to measure the concentration and density distribution along the jet axis and across it. A comparison with experimental and numerical results obtained by other authors when observing

  12. 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.

  13. Determination of the odor threshold concentrations of iodinated trihalomethanes in drinking water.

    PubMed

    Cancho, B; Fabrellas, C; Diaz, A; Ventura, F; Galceran, M T

    2001-04-01

    Iodinated trihalomethanes (ITHMs) have been usually considered the disinfection byproducts suspected of causing medicinal odor episodes in treated water around the world. The odor threshold concentration (OTC) of mixed ITHMs (bromochloroiodo-, bromodiiodo-, chlorodiiodo-, dibromoiodo-, and dichloroiodomethane) which were previously synthesized -- because commercial standards are not available-- were determined by using two sensory techniques: flavor profile analysis (FPA), performed by an experienced panel trained in identifying odors and tastes in water; and gas chromatography coupled with olfactometry (GCO). FPA results gave a theoretical OTCs range from 0.1 to 8.9 microg/L and ITHMs were described as sweet, solvent, and medicinal products. The lowest experimental value (OTC(exp)) obtained from the six ITHMs, 0.03 microg/L, corresponded to iodoform.

  14. Determination of the odor threshold concentrations of chlorobrominated anisoles in water.

    PubMed

    Diaz, Alfredo; Fabrellas, Cristina; Ventura, Francesc; Galceran, M Teresa

    2005-01-26

    Trihalophenols, which are drinking water disinfection byproducts (DBPs) formed by chlorination or chloramination practices, can be biomethylated into trihalogenated anisoles. These latter compounds have traditionally been suspected of causing odor episodes in drinking water around the world. The odor threshold concentration (OTC) of mixed chlorobrominated anisoles, which were previously synthesized, was determined by flavor profile analysis (FPA) performed by an experienced panel trained to identify odors and tastes in water. The odor threshold amount (OTA) was evaluated by using a gas chromatograph equipped with olfactometry (GC-O) and electron capture detectors (ECD). FPA results for mixed chlorobromoanisoles gave a theoretical OTCs range from 2 to 30 ng/L, the 2,6-diBr-3Cl-anisole being the most odorous compound. Rubber is the general descriptor described by panelists for these compounds, although earthy and musty are the following most cited descriptors.

  15. 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.

  16. 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.

  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. Validity of using semipermeable membrane devices for determining aqueous concentrations of freely dissolved PAHs

    USGS Publications Warehouse

    Prest, Harry; Petty, J.D.; Huckins, J.N.

    1998-01-01

    An in-depth review of the recent contribution to this journal by Gustafson and Dickhut [1] prompts us to share our concerns regarding some of their conclusions. The paper presents data comparing three techniques for determining aqueous concentrations of freely dissolved polycyclic aromatic hydrocarbons (PAHs) gas sparging, lipid-containing semipermeable membrane devices (SPMDs) of the U.S. Geological Survey (USGS) design, and filtration followed by sorption using XAD-2 resin. Space limitations force us to limit our comments to problems resulting from an apparent lack of understanding of how SPMDs function. Several recent publications [2–13] have described the theoretical and practical considerations of SPMD usage. Gustafson and Dickhut fail to cite any papers describing SPMDs published after 1992, even though some 18 papers have been published in American and European journals since then and several SPMD studies have been presented at many major meetings.

  19. Sampling and sample preparation methods for determining concentrations of mycotoxins in foods and feeds.

    PubMed

    2012-01-01

    Sample variation is often the largest error in determining concentrations of mycotoxins in food commodities. The worldwide safety evaluation of mycotoxins requires sampling plans that give acceptably accurate values for the levels of contamination in specific batches or lots of a commodity. Mycotoxin concentrations show a skewed or uneven distribution in foods and feeds, especially in whole kernels (or nuts), so it is extremely difficult to collect a sample that accurately represents the mean batch concentration. Sample variance studies and sampling plans have been published for select mycotoxins such as aflatoxin, fumonisin, and deoxynivalenol, emphasizing the importance of sample selection, sample size, and the number of incremental samples. For meaningful data to be generated from surveillance studies, representative samples should be collected from carefully selected populations (batches or lots) of food that, in turn, should be representative of clearly defined locations (e.g. a country, a region within a country). Although sampling variability is unavoidable, it is essential that the precision of the sampling plan be clearly defined and be considered acceptable by those responsible for interpreting and reporting the surveillance data. The factors influencing variability are detailed here, with reference to both major mycotoxins and major commodities. Sampling of large bag stacks, bulk shipments, and domestic supplies are all discussed. Sampling plans currently accepted in international trade are outlined. Acceptance sampling plans and the variabilities that affect operating characteristic curves of such plans are also detailed. The constraints and issues related to the sampling of harvested crops within subsistence farming areas are also discussed in this chapter, as are the essential rules of sample labelling and storage. The chapter concludes with a short section on sample preparation methods.

  20. Determination of eptifibatide concentration in human plasma utilizing the liquid chromatography-tandem mass spectrometry method.

    PubMed

    Liu, Jia; Duan, Xiaotao; Chen, Xiaoyan; Zhong, Dafang

    2009-02-15

    A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine the concentration of eptifibatide in human plasma. Following protein precipitation, the analyte was separated on a reversed-phase C(18) column. Acetonitrile:5mM ammonium acetate:acetic acid (30:70:0.1, v/v/v) was used at a flow-rate of 0.5mL/min with the isocratic mobile phase. An API 4000 tandem mass spectrometer equipped with a Turbo IonSpray ionization source was used as the detector and was operated in the positive ion mode. "Truncated" multiple reaction monitoring using the transition of m/z 832.6-->m/z 832.6 and m/z 931.3-->m/z 931.3 was performed to quantify eptifibatide and the internal standard (EPM-05), respectively. The method had a lower limit of quantification of 4.61ng/mL for eptifibatide. The calibration curve was demonstrated to be linear over the concentration range of 4.61-2770ng/mL. The intra- and inter-day precisions were less than 10.5% for each QC level, and the inter-day relative errors were 2.0%, 5.6%, and 2.8% for 9.22, 184, and 2490ng/mL, respectively. The validated method was successfully applied to the quantification of eptifibatide concentration in human plasma after intravenous (i.v.) administration of a 270-microg/kg bolus of eptifibatide and i.v. administration of eptifibatide at a constant rate of infusion of 2microg/(kgmin) for 18h in order to evaluate the pharmacokinetics.

  1. In vitro determination of glucose concentration based on photoacoustic spectroscopy and chemometrics

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2014-09-01

    Noninvasive blood glucose level (BGL) monitoring has recently become a research hotspot in the world. Photoacoustic spectroscopy is a well-established, hybrid and promising noninvasive technique, which has already drawn many researchers' attentions in recent years due to the advantage of overcoming the scattering light interference. As the preliminary exploration of photoacoustic BGL monitoring, a photoacoustic BGL monitoring set-up based on nanosecond pulsed laser with repetition rate of 20Hz and ultrasound transducer with central frequency of 9.55MHz was established in this paper. To explore the mechanism of the time resolved BGL photoacoustic signal, a series of in vitro experiments of glucose aqueous solutions were tested, the time resolved photoacoustic signals for different concentrations of glucose solutions under different output wavelengths were captured with the data average of 512 times. The peak-to-peak values of each solution were gotten at the wavelength interval of 10nm. Difference with the peak-to-peak value of pure water via subtractive spectroscopy, the characteristic wavelengths of glucose were gotten, and the optimum characteristic wavelengths were determined via data pre-processing and principle component analysis(PCA) algorithm, the calibration equation between concentration and the peak-to-peak value was gotten via multiple linear regression(MLR), and the calibration root mean square error(CRMSE) and the prediction root mean square error(PRMSE) of glucose level is all less than 10mg/dl under the correction equation.

  2. 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%).

  3. Determination of metal concentration in fat supplements for swine nutrition by atomic absorption spectroscopy.

    PubMed

    Cocchi, Marina; Faeti, Valerio; Manfredini, Matteo; Manzini, Daniela; Marchetti, Andrea; Sighinolfi, Simona

    2005-01-01

    The presence of some essential and toxic metals in fat supplements for swine diet was investigated. Collected samples represented a relevant production of the Italian industry. In particular, some samples were enriched with antioxidants or waste cooking oils. The method for the determination of Ca, Cu, Cd, Fe, Mg, Mn, Ni, Pb, and Zn in fat samples was developed by means of a certified reference material (CRM 186) and a representative fatty sample (RFS). All samples were digested in closed vessels in a microwave oven and then analyzed by flame atomic absorption or graphite furnace atomic absorption spectrometry. The entire analytical method provided a satisfactory repeatability and reproducibility confirmed by agreement between the experimental recovery data obtained for the CRM 186 sample and, with the method of standard additions, for the RFS material. The samples generally showed a small amount of metals compared with the recommended daily intake for the essential elements. On the other hand, some samples contained a significant concentration, from an analytical point of view, of Cd, Ni, and Pb. Principal component analysis (PCA) was applied to inspect the experimental data obtained from samples analysis. Basically no differences were detected in terms of metal concentration among the fat supplements analyzed.

  4. 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.

  5. Rapid determination of vitamin B12 concentration with a chemiluminescence lab on a chip.

    PubMed

    Lok, Khoi Seng; Abdul Muttalib, Siti Zubaidah binte; Lee, Peter Peng Foo; Kwok, Yien Chian; Nguyen, Nam-Trung

    2012-07-07

    This paper reports a novel method for the rapid determination of vitamin B(12) concentration in a continuous-flow lab-on-a-chip system. This new method is based on luminol-peroxide chemiluminescence (CL) assays for the detection of cobalt(II) ions in vitamin B(12) molecules. The lab-on-a-chip device consisted of two passive micromixers acting as microreactors and a double spiral microchannel network serving as an optical detection region. This system could operate in two modes. In the first mode, samples are acidified and evaluated directly in the microchip. In the second mode, samples are treated externally by acidification prior to detection in the microchip. In the first mode, the linear range obtained was between 1.00 ng ml(-1) to 10 μg ml(-1), R(2) = 0.996, with a relative standard deviation (RSD) of 1.23 to 2.31% (n = 5) and a limit of detection (lod) of 0.368 pg ml(-1). The minimum sample volume required and the analytical time were 30 μl and 3.6 s, respectively. In the second mode, the linear range obtained was between 0.10 ng ml(-1) to 10 μg ml(-1), R(2) = 0.994, with the RSD of 0.90 to 2.32% (n = 6) and a lod of 0.576 pg ml(-1). The minimum sample and the analytical time required were 50 μl and 6 s, respectively. The lab on a chip working in mode II was successfully used for the determination of vitamin B(12) concentrations in nutritional supplemental tablets and hen egg yolks.

  6. Determination of plasma lactic acid concentration and specific activity using high-performance liquid chromatography.

    PubMed

    Bleiberg, B; Steinberg, J J; Katz, S D; Wexler, J; LeJemtel, T

    1991-08-23

    Assessment of lactate metabolism is of particular interest during exercise and in disease states such as diabetes, shock, and absorptive abnormalities of short-chain fatty acids by the colon. We describe an analytical method that introduces radio-active tracers and high-performance liquid chromatography (HPLC) to simultaneously analyze concentrations and specific activities (SAs) of plasma lactate. The HPLC conditions included separation on a reversed-phase column (octadecylsilane) and an isocratic buffer (30% acetonitrile in water). [3H]Acetate served as an internal standard. Lactate and acetate were extracted from plasma samples with diethyl ether following a pH adjustment to less than 1.0 and back-extracted into a hydrophilic phase with sodium carbonate (2 mM, pH greater than 10.0). Lactate is detected in the ultraviolet range (242 and 320 nm) by derivatization with alpha-bromoacetophenone. Control plasma samples were studied after an overnight fast for precision and analytical recovery. Calibration curves were linear in the range 0.18-6.0 mM (r = 0.92). The precision was 3% and the analytical recovery was 87%. The detection limit of the method was 36 pmol. Determination of lactate metabolism was performed in a patient with chronic congestive heart failure who was administered primed-continuous L-[U-14C]lactate (10 microCi bolus and 0.3 microCi/min continuously) during a 60-min rest period. Mean arterial lactate concentration and SA were 1.69 +/- 0.2 mM and 253.8 +/- 22 dpm/mumol, respectively. Systemic lactate turnover was 25.65 mumol/kg per min. Lactic acid systemic turnover, organ uptake and release rates can be accurately determined by isocratic HPLC.

  7. 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.

  8. [Practical problems raised by antibiotic minimal inhibitory concentration determination in Legionella species (author's transl)].

    PubMed

    Bornstein, N; Roudier, C; Fleurette, J

    1982-06-01

    Because of culture medium constitution and growth conditions of Legionella species, antibiotic Minimal inhibitory Concentration (MIC) determination is difficult and does not fit with the accepted standards. The following strains have been tested : references strains : Staphylococcus aureus Oxford CNCM 53154, S. aureus 209P CNCM 53156, E. coli CNCM A224, E. coli CNCM 7324. L. pneumophila, 9 strains representative of the 6 serogroups. L. micdadei, L. dumoffii. 5 clinical isolates of L. pneumophila serogroup 1 (3 isolated in our Laboratory and 2 in Belgium). MIC of 17 antibiotics have been determined, among them macrolids not tested before. The method used was the Agar Dilution Method, with several media compared. MIC values are different in function of the various media tested Charcoal yeast extract medium, which is recommended for Legionella growth, does not inhibit activity of penicillin G, cefalotin, cefoxitin, amikacin, erythromycin and lincosamins, in contrast of tetracyclin, gentamicin, dibekacin, chloramphenicol, oleandomycin, pristinamycin, spiramycin and rifampicin. Charcoal, ferric pyrophosphate and L-cystein present in the culture medium are inactivating factors. However our results confirm good activity of rifampicin, erythromycin, cefoxitin, chloramphenicol, gentamicin and amikacin. Among the others macrolids tested, pristinamycin is the most active.

  9. A RAPID SPECTROSCOPIC TECHNIQUE FOR DETERMINING THE POTENTIAL ALPHA ENERGY CONCENTRATION OF RADON DECAY PRODUCTS

    SciTech Connect

    Revzan, K. L.; Nazaroff, W. W.

    1981-07-01

    We consider the application of alpha spectroscopy to the rapid determination of the potential alpha energy concentration (PAEC) of radon decay products indoors. Two count totals are obtained after a single counting period. The PAEC is then estimated by a linear combination of the count totals, the two coefficients being determined by analysis of the dependence of the statistical and procedural errors on the equilibrium conditions and the sampling, delay, and counting times. For a total measurement time of 11 min, the procedural error is unlikely to exceed 20% for equilibrium conditions commonly found indoors; the statistical error is less than 20% at a PAEC of 0.005 WL, assuming a product of detector efficiency and flow rate of at least 1.0 l/min. An analysis is made of techniques based on a total alpha count, and the results are compared with those obtained with the rapid spectroscopic technique; the latter is clearly preferable when the measurement time does not exceed 15 min.

  10. Development of novel potentiometric sensors for determination of tartrazine dye concentration in foodstuff products.

    PubMed

    Abu Shawish, Hazem M; Ghalwa, Nasser Abu; Saadeh, Salman M; El Harazeen, Heba

    2013-05-01

    Tartrazine dye Na(3)TZ in foodstuff products was determined by a new modified carbon paste electrode, encoded sensor A, and a coated silver wire electrode, encoded sensor B, based on tartrazine TZ- cetryltrimethyl ammoniumbromide CTAB as a chemical modifier TZ-CTA. The electrodes exhibit the following characteristics listed respectively: a Nernstian slope of 17.9±0.5 and 19.4±0.2 mV/decade for tartrazine ion over a wide concentration range from 4.3×10(-7) to 1.0×10(-2) and 1.1×10(-7) to 1.0×10(-2) M. The lower detection limits: 3.2×10(-7) and 5.5×10(-8) M. Short response time (5-8 s) over the pH range 3.8-7.7 and 4.2-8.1. The proposed sensors display significantly high selectivity for TZ ion over a wide variety of sugars, some anions, common organic, inorganic compounds and additives. The developed electrodes were applied to the potentiometric determination of tartrazine ion in different kinds of foodstuffs: solid jelly (strawberry and custard) powder samples and soft drink (orange) samples with satisfactory results.

  11. Determination of iron in drinking water after its flotation concentration by two new dithiocarbamate collectors.

    PubMed

    Pavlovska, Gorica; Stafilov, Trajče; Čundeva, Katarina

    2015-01-01

    Two new methods for the determination of iron by atomic absorption spectrometry (AAS) are proposed for drinking water. The determination was made after flotation concentration of Fe by using of two new flotation collectors: lead(II) heptyldithiocarbamate, Pb(HpDTC)2 and cobalt(III) heptyldithiocarbamate Co(HpDTC)3. All important parameters for the two proposed procedures were optimised (pH, mass of Pb, mass of Co, amount of HpDTC(-), type of surfactant, induction time, etc.). Flotation recovery (R) of Fe was very high (from 94.4 to 104.4%) for the two proposed procedures. The detection limit of the methods was 2.17 μg L(-1) for Pb(HpDTC)2 and 2.39 μg L(-1) for Co(HpDTC)3, respectively. The proposed methods have been applied for the analysis of five samples of drinking water. The acquired AAS results for Fe by both new methods were compared with those obtained by inductively coupled plasma-atomic emission spectrometry (AES-ICP). It is shown that they are in good agreement. The results are also confirmed by the method of standard additions.

  12. A new reference method for the determination of the total CO2 concentration in biological fluids.

    PubMed

    Dijkhuizen, P; Fongers, T M; Rispens, P; Zijlstra, W G

    1978-06-15

    It appeared that a part of a measuring system recently developed for the determination of the oxygen content of blood (Dijkhuizen, P., Kwant, G. and Zijlstra, W.G. (1976) Clin. Chim. Acta 68, 79), was perfectly suitable for measuring the total CO2 content of blood, plasma or other fluids. CO2-free room air is pumped through an extraction vessel in which all the CO2 of the sample is set free by an acid reagent, and swept by the carrier gas to a titration vessel containing a BaCl2 solution. CO2 is bound as BaCO3 and the ensuing H+ titrated with an NaOH solution. The method was tested by measuring a series of Na2CO3 reference solutions. The values measured by titration amounted to 99.4 +/- 0.8% of the concentration of the reference solutions (range 10--50 mmol 1(-1). The coefficient of variation was 1.8% for 5 mmol 1(-1) solutions and 0.2% for 50 mmol 1(-1) solutions. In measuring a series of 60 blood samples the coefficient of variation as calculated from duplicate determinations was 1%.

  13. Cryogenic, Absolute, High Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

    2001-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  14. 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).

  15. 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.

  16. Absolute measurement of length with nanometric resolution

    NASA Astrophysics Data System (ADS)

    Apostol, D.; Garoi, F.; Timcu, A.; Damian, V.; Logofatu, P. C.; Nascov, V.

    2005-08-01

    Laser interferometer displacement measuring transducers have a well-defined traceability route to the definition of the meter. The laser interferometer is de-facto length scale for applications in micro and nano technologies. However their physical unit -half lambda is too large for nanometric resolution. Fringe interpolation-usual technique to improve the resolution-lack of reproducibility could be avoided using the principles of absolute distance measurement. Absolute distance refers to the use of interferometric techniques for determining the position of an object without the necessity of measuring continuous displacements between points. The interference pattern as produced by the interference of two point-like coherent sources is fitted to a geometric model so as to determine the longitudinal location of the target by minimizing least square errors. The longitudinal coordinate of the target was measured with accuracy better than 1 nm, for a target position range of 0.4μm.

  17. [Effect of ligand concentration on the precision of determining the parameters of ligand-receptor interaction by serial dilution methods].

    PubMed

    Bobrovnik, S A

    2004-01-01

    Earlier we suggested the method of serial dilution, which allows one to determine the parameters of ligand-receptor interaction even if the reactants are in a mixture and their concentrations are unknown. The method is especially useful if the liability of studied receptor does not allow its separation from corresponding ligand. The important prerequisite of the method's precision is that the concentration of the ligand should be sufficiently high comparing to the concentration of the receptor. In the present paper it was demonstrated that the method allows one to obtain sufficiently good precision even in the case when the concentration of the ligand is only one tenth of the receptor concentration.

  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.

  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. Use of Solid-Phase Extraction To Determine Ergosterol Concentrations in Plant Tissue Colonized by Fungi

    PubMed Central

    Gessner, M. O.; Schmitt, A. L.

    1996-01-01

    At present, the ergosterol and acetate-to-ergosterol techniques are generally considered to be the methods of choice to quantify fungal biomass, growth rate, and productivity under natural conditions. Both methods rely on the accurate isolation and quantification of ergosterol, a major membrane component of eumycotic fungi. Taking advantage of the solid-phase extraction (SPE) technique, we present a novel method to determine the ergosterol concentration in lipid extracts derived from plant tissues and dead organic matter colonized by fungi. In this method, a primary alkaline extract is acidified and passed through a reversed-phase (C(inf18)) SPE column. The column is then washed with an alkaline methanol-water solution to eliminate interfering substances and increase pH and is thoroughly dried in air. Ergosterol is eluted with alkaline isopropanol. This eluting solvent was chosen to produce a strongly basic pH of the final extract and thus confer stability on the ergosterol molecule before high-performance liquid chromatography analysis. The recovery of ergosterol from plant tissues and the O(infhf) horizon of a woodland soil ranged from 85 to 98%, and the overall extraction efficiency was similar to that obtained by a conventional procedure involving liquid-liquid extraction. Potential pitfalls of ergosterol analysis by SPE include (i) insufficient acidification before sample loading on the extraction column, resulting in a poor affinity of ergosterol for the sorbent; (ii) incomplete drying of the sorbent bed before the elution step; and (iii) chemical breakdown of ergosterol after elution, which was found to be related to a low pH of the final extract and a high concentration of matrix compounds. When these pitfalls are avoided, SPE is an attractive alternative to existing methods of ergosterol analysis of environmental samples. PMID:16535229

  1. Determinants of the serum concentrations of low molecular weight proteins in patients on maintenance hemodialysis.

    PubMed

    Kabanda, A; Jadoul, M; Pochet, J M; Lauwerys, R; van Ypersele de Strihou, C; Bernard, A

    1994-06-01

    Factors influencing the serum concentrations of low molecular weight proteins (LMWP) during long-term hemodialysis were studied in 112 patients undergoing dialysis for an average of 61.1 months (range 1 to 243). These patients were treated with AN69, cellulose acetate, cuprophan or polysulfone membranes. The following proteins were measured in serum before and after a four hour dialysis session: cystatin C (CYST C), beta 2-microglobulin (beta 2 m), Clara cell protein (CC16) and retinol-binding protein (RBP). Predialysis levels of the four proteins were markedly elevated. In simple regression analysis, pre-dialysis serum concentrations of beta 2 m and CC16 weakly correlated with the duration of dialysis treatment, but these relations completely disappeared when a stepwise regression analysis was performed using as predictors age, sex, residual diuresis, body weight loss (BWL), duration of hemodialysis and the type or ultrafiltration coefficient (UFC) of the membranes. The only significant determinants which emerged from this analysis were the residual diuresis and age which negatively correlated with CYST C, beta 2m and CC16 (residual diuresis only), and sex which influenced CYST C. During the dialysis session, the microproteins underwent changes that were related to their molecular radius, the membrane UFC and the BWL. After adjustment for the latter, high flux membranes (UFC > or = 15 ml/h.m2.mm Hg) allowed up to 50% of CYST C and 25% of beta 2m to be removed. No significant elimination of CC16 and RBP was evident. On the basis of these results, we estimated the effective pore radius of high flux membranes between 1.5 and 1.7 nm and that of low flux membranes as below 1.5 nm.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Absolute and relative emissions analysis in practical combustion systems—effect of water vapor condensation

    NASA Astrophysics Data System (ADS)

    Richter, J. P.; Mollendorf, J. C.; DesJardin, P. E.

    2016-11-01

    Accurate knowledge of the absolute combustion gas composition is necessary in the automotive, aircraft, processing, heating and air conditioning industries where emissions reduction is a major concern. Those industries use a variety of sensor technologies. Many of these sensors are used to analyze the gas by pumping a sample through a system of tubes to reach a remote sensor location. An inherent characteristic with this type of sampling strategy is that the mixture state changes as the sample is drawn towards the sensor. Specifically, temperature and humidity changes can be significant, resulting in a very different gas mixture at the sensor interface compared with the in situ location (water vapor dilution effect). Consequently, the gas concentrations obtained from remotely sampled gas analyzers can be significantly different than in situ values. In this study, inherent errors associated with sampled combustion gas concentration measurements are explored, and a correction methodology is presented to determine the absolute gas composition from remotely measured gas species concentrations. For in situ (wet) measurements a heated zirconium dioxide (ZrO2) oxygen sensor (Bosch LSU 4.9) is used to measure the absolute oxygen concentration. This is used to correct the remotely sampled (dry) measurements taken with an electrochemical sensor within the remote analyzer (Testo 330-2LL). In this study, such a correction is experimentally validated for a specified concentration of carbon monoxide (5020 ppmv).

  3. 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

  4. Determination of thromboxane formation, soluble CD40L release and thrombopoietin clearance in apheresis platelet concentrates.

    PubMed

    Wenzel, Folker; Baertl, Anja; Hohlfeld, Thomas; Zimmermann, Norbert; Weber, Artur Aron; Lorenz, Horst; Giers, Günther

    2012-01-01

    All deleterious changes in platelet morphology, structure and function that occur in platelet concentrates (PC) during storage are titled as the 'platelet storage lesion'. No single in vitro test currently available is sufficient in assessing these changes of platelet quality. The release of soluble CD40 Ligand (sCD40L), the formation of thromboxane (TXB2) and the thrombopoietin (TPO) clearance reflect different aspects of platelet metabolism and activitiy, and were used to examine platelet quality in apheresis platelet products. At days 1, 3 and 5, in single-donor apheresis platelet products (n = 10) under routine storage conditions, sCD40L (measured by ELISA) and TXB2 (measured by RIA) were determined after platelet stimulation (recalcification and clot formation). TPO (measured by ELISA) was determined after an incubation time of 5 h at 37°C with platelet-rich plasma (adjusted initial TPO concentration of about 500 pg/mL). Results were related to a therapeutic unit (TU = 2 × 10(11) platelets). Immediately after platelet preparation, sCD40L release was 41 ± 7.6 ng/TU, TXB2 formation 1688 ± 374 ng/TU and TPO clearance 1.22 ± 0.32 ng/h/TU. At days 1, 3 and 5, sCD40L was reduced to 89 ± 7%, 71 ± 12% and 57 ± 9%, TXB2 release to 91 ± 6%, 74 ± 12% and 58 ± 9% and TPO clearance to 90 ± 15%, 84 ± 5% and 79 ± 10% of the respective control values. In conclusion, in single-donor apheresis PC, sCD40L release and TXB2 formation as well as TPO clearance by the platelets were dependent on storage duration and reduced to about 60% to 80% of the respective control values after a storage period for 5 days. These findings are in line with literature data, indicating that a loss of platelet functionality of about 30% will occur after 5 days of storage.

  5. Absolute Radiation Thermometry in the NIR

    NASA Astrophysics Data System (ADS)

    Bünger, L.; Taubert, R. D.; Gutschwager, B.; Anhalt, K.; Briaudeau, S.; Sadli, M.

    2017-04-01

    A near infrared (NIR) radiation thermometer (RT) for temperature measurements in the range from 773 K up to 1235 K was characterized and calibrated in terms of the "Mise en Pratique for the definition of the Kelvin" (MeP-K) by measuring its absolute spectral radiance responsivity. Using Planck's law of thermal radiation allows the direct measurement of the thermodynamic temperature independently of any ITS-90 fixed-point. To determine the absolute spectral radiance responsivity of the radiation thermometer in the NIR spectral region, an existing PTB monochromator-based calibration setup was upgraded with a supercontinuum laser system (0.45 μm to 2.4 μm) resulting in a significantly improved signal-to-noise ratio. The RT was characterized with respect to its nonlinearity, size-of-source effect, distance effect, and the consistency of its individual temperature measuring ranges. To further improve the calibration setup, a new tool for the aperture alignment and distance measurement was developed. Furthermore, the diffraction correction as well as the impedance correction of the current-to-voltage converter is considered. The calibration scheme and the corresponding uncertainty budget of the absolute spectral responsivity are presented. A relative standard uncertainty of 0.1 % (k=1) for the absolute spectral radiance responsivity was achieved. The absolute radiometric calibration was validated at four temperature values with respect to the ITS-90 via a variable temperature heatpipe blackbody (773 K ...1235 K) and at a gold fixed-point blackbody radiator (1337.33 K).

  6. 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

  7. The determination of carbon dioxide concentration using atmospheric pressure ionization mass spectrometry/isotopic dilution and errors in concentration measurements caused by dryers.

    PubMed

    DeLacy, Brendan G; Bandy, Alan R

    2008-01-01

    An atmospheric pressure ionization mass spectrometry/isotopically labeled standard (APIMS/ILS) method has been developed for the determination of carbon dioxide (CO(2)) concentration. Descriptions of the instrumental components, the ionization chemistry, and the statistics associated with the analytical method are provided. This method represents an alternative to the nondispersive infrared (NDIR) technique, which is currently used in the atmospheric community to determine atmospheric CO(2) concentrations. The APIMS/ILS and NDIR methods exhibit a decreased sensitivity for CO(2) in the presence of water vapor. Therefore, dryers such as a nafion dryer are used to remove water before detection. The APIMS/ILS method measures mixing ratios and demonstrates linearity and range in the presence or absence of a dryer. The NDIR technique, on the other hand, measures molar concentrations. The second half of this paper describes errors in molar concentration measurements that are caused by drying. An equation describing the errors was derived from the ideal gas law, the conservation of mass, and Dalton's Law. The purpose of this derivation was to quantify errors in the NDIR technique that are caused by drying. Laboratory experiments were conducted to verify the errors created solely by the dryer in CO(2) concentration measurements post-dryer. The laboratory experiments verified the theoretically predicted errors in the derived equations. There are numerous references in the literature that describe the use of a dryer in conjunction with the NDIR technique. However, these references do not address the errors that are caused by drying.

  8. 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.

  9. An on-line pre-concentration system for determination of cadmium in drinking water using FAAS.

    PubMed

    dos Santos, Walter N L; Costa, Jorge L O; Araujo, Rennan G O; de Jesus, Djane S; Costa, Antônio C S

    2006-10-11

    In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variables: sampling flow rate, elution concentration, buffer concentration and pH. Using the established experimental conditions in the optimization step of: pH 8.2, sampling flow rate 8.5 mL min(-1), buffer concentration 0.05 mol L(-1) and elution concentration of 1.0 mol L(-1), this system allows the determination of cadmium with detection limit (LD) (3sigma/S) of 20.0 ng L(-1) and quantification limit (LQ) (10sigma/S) of 64 ng L(-1), precision expressed as relative standard deviation (R.S.D.) of 5.0 and 4.7% for cadmium concentration of 5.0 and 40.0 microg L(-1), respectively, and a pre-concentration factor of 158 for a sample volume of 20.0 mL. The accuracy was confirmed by cadmium determination in the standard reference material, NIST SRM 1643d trace elements in natural water. This procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. For five samples analyzed, the achieved concentrations varied from 0.31 to 0.86 microg L(-1).

  10. 40 CFR Appendix A to Subpart Uuu... - Determination of Metal Concentration on Catalyst Particles (Instrumental Analyzer Procedure)

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... on Catalyst Particles (Instrumental Analyzer Procedure) A Appendix A to Subpart UUU of Part 63...—Determination of Metal Concentration on Catalyst Particles (Instrumental Analyzer Procedure) 1.0Scope and... analyte concentrations on catalyst particles. This method is applicable for catalyst particles...

  11. 40 CFR Appendix A to Subpart Uuu... - Determination of Metal Concentration on Catalyst Particles (Instrumental Analyzer Procedure)

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... on Catalyst Particles (Instrumental Analyzer Procedure) A Appendix A to Subpart UUU of Part 63...—Determination of Metal Concentration on Catalyst Particles (Instrumental Analyzer Procedure) 1.0Scope and... analyte concentrations on catalyst particles. This method is applicable for catalyst particles...

  12. Macromolecular geometries determined with field-flow fractionation and their impact on the overlap concentration.

    PubMed

    Rojas, Cinthia Carola; Wahlund, Karl-Gustav; Bergenståhl, Björn; Nilsson, Lars

    2008-06-01

    In this paper we aim to understand the size/conformation relationship in waxy barley starch, a polydisperse and ultrahigh molar mass biomacromolecule. Characterizations are performed with asymmetrical flow field-flow fractionation (AsFlFFF). Furthermore, we study the effect of homogenization on the molar mass, rms radius (r rms) and hydrodynamic radius (r h). For the untreated sample, the macromolecules are elongated objects with low apparent density. As a result of homogenization, molar mass, and r rms decrease, while r h remains unaffected. The process also induces an increase, and scaling with size, of apparent density as well as changes in conformation, represented qualitatively by r rms/ r h. Finally, results from AsFlFFF are compared with viscosimetry and discussed in terms of concentration and close-packing in relation to macromolecular shape and conformation. Hence, the results show that AsFlFFF and our novel methodology enable the determination of several physical properties with high relevance for the solution behavior of polydisperse macromolecules.

  13. 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.

  14. 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.

  15. A comparative study of analytical methods to determine postmortem changes in carbon monoxide concentration.

    PubMed

    Winek, C L; Prex, D M

    1981-01-01

    Twenty-one autopsy blood samples were analyzed using spectrophotometric and gas chromatographic procedures after storage for 30 and 150 days. When carboxyhemoglobin was measured spectrophotometrically at the absorbance ratio of 540 nm/555 nm, the observed average percent losses were 8 +/- 9% and 35 +/- 27% after 30 and 150 days of storage, respectively. When measured at the absorbance ratio of 540 nm/579 nm, the average percent losses of carboxyhemoglobin were 7 +/- 8% and 34 +/- 25% after 30 and 150 days, respectively. Wavelength shifts and distorted spectral scans were observed at 150 days. When carbon monoxide was determined by gas chromatographic methods based on combining capacity, the average percent loss was 15 +/- 24% and 37 +/- 36% after 30 days and 150 days, respectively. The average percent loss of calculated CO based on hemoglobin concentration after 30 days was 31 +/- 14% and at 150 days, 40 +/- 24%. The average percent loss of calculated CO based on iron content was 23 +/- 13% and 37 +/- 23% after 30 and 150 days, respectively.

  16. 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.

  17. Determination of thalidomide concentration in human plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Bai, Nan; Cui, Xiang-Yong; Wang, Jin; Sun, Chun-Guang; Mei, He-Kun; Liang, Bei-Bei; Cai, Yun; Song, Xiu-Jie; Gu, Jing-Kai; Wang, Rui

    2013-02-01

    A rapid, sensitive and specific analytical method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of thalidomide concentration in human plasma. The analyte and internal standard were extracted by liquid-liquid extraction with ether-dichloromethane (3:2, v/v) and separated on a TC-C(18) column using methanol-10 mM ammonium acetate-formic acid (60:40:0.04, v/v/v) as the mobile phase at a flow rate of 0.9 ml/min. The detection was performed using an API 4000 triple quadrupole mass spectrometer in the positive electrospray ionization (ESI) mode and completed within 3.0 min. The multiple reaction monitoring (MRM) transitions were m/z 259.1→84.0 for the analyte and m/z 195.9→138.9 for temozolomide. The calibration curve exhibited a linear dynamic range of 2-1500 ng/ml (r>0.9991). The intra-and inter-day precisions (as relative standard deviation; RSD) were 6.8-13.5% and 4.3-5.0% respectively and the accuracy (as relative error; RE) was 2.0-3.5%. The recoveries and matrix effects were satisfactory in all the biological matrices examined. This method was successfully used in a pharmacokinetic study of thalidomide in healthy male volunteers receiving an oral administration of a 200-mg dose.

  18. The Rate of Concentration Change and How It Determines the Resolving Power of Olfactory Receptor Neurons

    PubMed Central

    Tichy, Harald; Hellwig, Maria; Zopf, Lydia M.

    2016-01-01

    The response characteristics of olfactory receptor neurons (ORNs) and their corollary, the differential sensitivity and the resolving power, are fundamental to understand olfactory coding and the information extracted from a fluctuating olfactory signal. Previous work has focused on the temporal resolution of odor pulses presented for very brief periods at varying concentrations. The time course of the odor pulses as a stimulus parameter has not been considered. The present study investigated the precision of the ON and OFF ORNs on the antennae of the cockroach to discriminate increments and decrements of continuously rising and falling odor concentrations. Stimulation consisted of ramp-like upward and downward concentration changes in a trapezoid fashion. By varying ramp steepness, we examined the effect of the rate of concentration change. Both ORNs were clearly dependent on continuously rising and falling odor concentrations. As the rate of upward and downward concentration changes increases, differential sensitivity improves. Since the scatter of responses around the stimulus-response functions also increases, the resolving power for concentration increments and decrements deteriorates. Thus, the slower the rate of concentration change, the higher the precision in differentiating small concentration changes. Intuitively, the inverse relationship between the rate of concentration change and the resolving power is not surprising because accuracy requires time. A high degree of precision at slow concentration rates enables the cockroach to use information about the onset and offset slopes of odor pulses in addition to the pulse height to encode the spatial-temporal structure of turbulent odor plumes. PMID:28082912

  19. Database applicaton for absolute spectrophotometry

    NASA Astrophysics Data System (ADS)

    Bochkov, Valery V.; Shumko, Sergiy

    2002-12-01

    32-bit database application with multidocument interface for Windows has been developed to calculate absolute energy distributions of observed spectra. The original database contains wavelength calibrated observed spectra which had been already passed through apparatus reductions such as flatfielding, background and apparatus noise subtracting. Absolute energy distributions of observed spectra are defined in unique scale by means of registering them simultaneously with artificial intensity standard. Observations of sequence of spectrophotometric standards are used to define absolute energy of the artificial standard. Observations of spectrophotometric standards are used to define optical extinction in selected moments. FFT algorithm implemented in the application allows performing convolution (deconvolution) spectra with user-defined PSF. The object-oriented interface has been created using facilities of C++ libraries. Client/server model with Windows Socket functionality based on TCP/IP protocol is used to develop the application. It supports Dynamic Data Exchange conversation in server mode and uses Microsoft Exchange communication facilities.

  20. Absolute and relative dosimetry for ELIMED

    NASA Astrophysics Data System (ADS)

    Cirrone, G. A. P.; Cuttone, G.; Candiano, G.; Carpinelli, M.; Leonora, E.; Lo Presti, D.; Musumarra, A.; Pisciotta, P.; Raffaele, L.; Randazzo, N.; Romano, F.; Schillaci, F.; Scuderi, V.; Tramontana, A.; Cirio, R.; Marchetto, F.; Sacchi, R.; Giordanengo, S.; Monaco, V.

    2013-07-01

    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.

  1. Absolute classification with unsupervised clustering

    NASA Technical Reports Server (NTRS)

    Jeon, Byeungwoo; Landgrebe, D. A.

    1992-01-01

    An absolute classification algorithm is proposed in which the class definition through training samples or otherwise is required only for a particular class of interest. The absolute classification is considered as a problem of unsupervised clustering when one cluster is known initially. The definitions and statistics of the other classes are automatically developed through the weighted unsupervised clustering procedure, which is developed to keep the cluster corresponding to the class of interest from losing its identity as the class of interest. Once all the classes are developed, a conventional relative classifier such as the maximum-likelihood classifier is used in the classification.

  2. 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.

  3. 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.

  4. Precise determination of U isotopic compositions in low concentration carbonate samples by MC-ICP-MS.

    PubMed

    Wang, Ruo-Mei; You, Chen-Feng

    2013-03-30

    We developed a fast and simple analytical procedure for precise determination of U isotopic compositions in low concentration natural samples. The main advantage of the new method is that it requires only 12ng U and can obtain all U isotopic ratios without using spike. Five carbonate reference materials (JCp-1, RKM-4, RKM-5, GBW04412 and GBW04413) and 3 international standards with different matrices (IAPSO, IRMM-3184 and CRM-U010) were analyzed for ((234)U/(238)U) and (238)U/(235)U ratios by MC-ICPMS. Using our method, the results for these standards are in close agreement with the certified values, 1.144 ± 0.004, 0.966 ± 0.004 and 0.990 ± 0.003 for ((234)U/(238)U) and 137.72 ± 0.13, 137.64 ± 0.15 and 98.63 ± 0.04 for (238)U/(235)U, in IAPSO, IRMM-3184 and CRM-U010, respectively. The long-term reproducibility of ((234)U/(238)U) and (238)U/(235)U is 0.970 ± 0.002 and 137.56 ± 0.09; 1.144 ± 0.004 and 137.72 ± 0.13, respectively, for in-house U solution and IAPSO. The new ((234)U/(238)U) results for carbonates show much better precision than previous studies and also reflect their age variability. The obtained (238)U/(235)U ratios, representing the first measurements in these carbonate specimens, are rather constant. The method described here requires only 12 ng of U for analysis and can be completed in 5.2 min. The approach provides a fast method to measure ((234)U/(238)U) and (238)U/(235)U ratios in sample matrices commonly encountered in studies of chemical weathering, oceanography and paleoclimatology.

  5. 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).

  6. In vivo absorption spectroscopy for absolute measurement.

    PubMed

    Furukawa, Hiromitsu; Fukuda, Takashi

    2012-10-01

    In in vivo spectroscopy, there are differences between individual subjects in parameters such as tissue scattering and sample concentration. We propose a method that can provide the absolute value of a particular substance concentration, independent of these individual differences. Thus, it is not necessary to use the typical statistical calibration curve, which assumes an average level of scattering and an averaged concentration over individual subjects. This method is expected to greatly reduce the difficulties encountered during in vivo measurements. As an example, for in vivo absorption spectroscopy, the method was applied to the reflectance measurement in retinal vessels to monitor their oxygen saturation levels. This method was then validated by applying it to the tissue phantom under a variety of absorbance values and scattering efficiencies.

  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. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  10. Absolute Standards for Climate Measurements

    NASA Astrophysics Data System (ADS)

    Leckey, J.

    2016-10-01

    In a world of changing climate, political uncertainty, and ever-changing budgets, the benefit of measurements traceable to SI standards increases by the day. To truly resolve climate change trends on a decadal time scale, on-orbit measurements need to be referenced to something that is both absolute and unchanging. One such mission is the Climate Absolute Radiance and Refractivity Observatory (CLARREO) that will measure a variety of climate variables with an unprecedented accuracy to definitively quantify climate change. In the CLARREO mission, we will utilize phase change cells in which a material is melted to calibrate the temperature of a blackbody that can then be observed by a spectrometer. A material's melting point is an unchanging physical constant that, through a series of transfers, can ultimately calibrate a spectrometer on an absolute scale. CLARREO consists of two primary instruments: an infrared (IR) spectrometer and a reflected solar (RS) spectrometer. The mission will contain orbiting radiometers with sufficient accuracy to calibrate other space-based instrumentation and thus transferring the absolute traceability. The status of various mission options will be presented.

  11. 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.

  12. An advanced passive diffusion sampler for the determination of dissolved gas concentrations

    NASA Astrophysics Data System (ADS)

    Gardner, P.; Solomon, D. K.

    2009-06-01

    We have designed and tested a passive headspace sampler for the collection of noble gases that allows for the precise calculation of dissolved gas concentrations from measured gas mixing ratios. Gas permeable silicon tubing allows for gas exchange between the headspace in the sampler volume and the dissolved gases in the adjacent water. After reaching equilibrium, the aqueous-phase concentration is related to the headspace concentration by Henry's law. Gas exchange between the water and headspace can be shut off in situ, preserving the total dissolved gas pressure upon retrieval. Gas samples are then sealed in an all metal container, retaining even highly mobile helium. Dissolved noble gas concentrations measured in these diffusion samplers are in good agreement with traditional copper tube aqueous-phase samples. These significantly reduce the laboratory labor in extracting the gases from a water sample and provide a simple and robust method for collecting dissolved gas concentrations in a variety of aqueous environments.

  13. Technical note: Effect of determining baseline plasma urea nitrogen concentrations on subsequent posttreatment plasma urea nitrogen concentrations in 20- to 50-kilogram pigs.

    PubMed

    Waguespack, A M; Powell, S; Roux, M L; Frugé, E D; Bidner, T D; Payne, R L; Southern, L L

    2011-12-01

    Plasma urea N (PUN) has been used as an indicator of AA requirements and efficiency of AA utilization in swine. However, PUN concentrations vary among a population of pigs, even a population with a close range of BW and fed the same diet. Thus, pretreatment or baseline PUN concentrations are used as a covariate to reduce variation of posttreatment PUN. However, this procedure increases experimental costs and stress to the pigs. Data from 14 experiments (26 to 28 d in duration) conducted using PUN as a response variable were compiled into 1 data set. Each experiment had 4 to 6 treatments. The purpose of this technical report was to summarize the effect of determining pretreatment baseline PUN concentrations on subsequent posttreatment PUN concentrations in 20- to 50-kg pigs. In all experiments, pigs were fed corn- and soybean meal-based diets and low-CP diets with various AA additions; pigs were assigned to dietary treatments in a randomized complete block design with a minimum of 4 replicates of 3 to 5 pigs each. Before the start of each experiment, all pigs were fed a common diet for a minimum of 3 d. Blood samples were collected from each pig before allotment to dietary treatments (d 0) and at the end of each experiment. The baseline (d 0) PUN was analyzed as a covariate for posttreatment PUN. Data from each experiment were analyzed without and with baseline PUN in the statistical model. In all experiments combined, there were 768 possible treatment comparisons. The covariate baseline PUN was statistically significant (P < 0.10) in 9 of 14 experiments. However, only 8 treatment differences changed statistical significance as a result of analyzing the data with baseline PUN as a covariate. These 8 treatment differences were in 3 experiments. These results indicate that it is not always necessary to determine baseline PUN concentrations when feeding diets with large differences in AA content.

  14. System for absolute measurements by interferometric sensors

    NASA Astrophysics Data System (ADS)

    Norton, Douglas A.

    1993-03-01

    The most common problem of interferometric sensors is their inability to measure absolute path imbalance. Presented in this paper is a signal processing system that gives absolute, unambiguous reading of optical path difference for almost any style of interferometric sensor. Key components are a wide band (incoherent) optical source, a polychromator, and FFT electronics. Advantages include no moving parts in the signal processor, no active components at the sensor location, and the use of standard single mode fiber for sensor illumination and signal transmission. Actual absolute path imbalance of the interferometer is determined without using fringe counting or other inferential techniques. The polychromator extracts the interference information that occurs at each discrete wavelength within the spectral band of the optical source. The signal processing consists of analog and digital filtering, Fast Fourier analysis, and a peak detection and interpolation algorithm. This system was originally designed for use in a remote pressure sensing application that employed a totally passive fiber optic interferometer. A performance qualification was made using a Fabry-Perot interferometer and a commercially available laser interferometer to measure the reference displacement.

  15. 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.

  16. Determination of odour threshold concentration ranges for some disinfectants and disinfection by-products for an Australian panel.

    PubMed

    McDonald, S; Lethorn, A; Loi, C; Joll, C; Driessen, H; Heitz, A

    2009-01-01

    Taste-and-odour complaints are a leading cause of consumer dissatisfaction with drinking water. The aim of this study was to determine odour threshold concentration ranges and descriptors, using a Western Australian odour panel, for chlorine, bromine, chlorine added to bromide ions, the four major regulated trihalomethanes (THMs), and combined THMs. An odour panel was established and trained to determine odour threshold concentration ranges for odorous compounds typically found in drinking water at 25 degrees C, using modified flavour profile analysis (FPA) techniques. Bromine and chlorine had the same odour threshold concentration ranges and were both described as having a chlorinous odour by a majority of panellists, but the odour threshold concentration range of bromine expressed in free chlorine equivalents was lower that that of chlorine. It is likely that the free chlorine equivalent residuals measured in many parts of distribution systems in Western Australia are comprised of some portion of bromine and that bromine has the potential to cause chlorinous odours at a lower free chlorine equivalent concentration than chlorine itself. In fact, bromine is the likely cause of any chlorinous odours in Western Australian distributed waters when the free chlorine equivalent concentration is between 0.04 and 0.1 mg L(-1). Odour threshold concentrations for the four individual THMs ranged from 0.06-0.16 mg L(-1), and the odour threshold concentration range was 0.10 + or - 0.09 mg L(-1) when the four THMs were combined (in equal mass concentrations). These concentrations are below the maximum guideline value for total THM concentration in Australia so odours from these compounds may possibly be observed in distributed waters. However, while the presence of THMs may contribute to any sweet/fragrant/floral and chemical/hydrocarbon odours in local drinking waters, the THMs are unlikely to contribute to chlorinous odours.

  17. A method for determination of methyl chloride concentration in air trapped in ice cores.

    PubMed

    Saito, Takuya; Yokouchi, Yoko; Aoki, Shuji; Nakazawa, Takakiyo; Fujii, Yoshiyuki; Watanabe, Okitsugu

    2006-05-01

    A method for measuring the concentration of methyl chloride (CH3Cl) in air trapped in an ice core was developed. The method combines the air extraction by milling the ice core samples under vacuum and the analysis of the extracted air with a cryogenic preconcentration/gas chromatograph/mass spectrometry system. The method was applied to air from Antarctic ice core samples estimated to have been formed in the pre-industrial and/or early industrial periods. The overall precision of the method deduced from duplicate ice core analyses was estimated to be better than +/-20 pptv. The measured CH3Cl concentration of 528+/-26 pptv was similar to the present-day concentration in the remote atmosphere as well as the CH3Cl concentration over the past 300 years obtained from Antarctic firn air and ice core analyses.

  18. 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...

  19. Fast determination of radon progeny concentrations. Report No. MRL 90-142(TR)

    SciTech Connect

    Bigu, J.; Edwardson, E.

    1990-01-01

    A technical evaluation of four Rn222 progeny measuring instruments (the Pylon WL-1000C, the MDA IWLM-811, the MIMIL IIM, and the EDA WLM-30) was conducted under laboratory controlled conditions and at several locations in an underground uranium mine. The laboratory evaluation consisted of a thorough study of the behaviour and performance of the instruments under a wide variety of environmental conditions, such as Rn222 gas concentration, Rn222 progeny concentration, temperature, relative humidity, aerosol concentration, and gamma-field exposure. The readings of the instruments were compared with the Thomas-Tsivoglou method, a widely accepted Rn222 progeny concentration measuring method. The instruments were rated according to accuracy, convenience of use, reliability, and ease of operation.

  20. A new method to determine the oxygen concentration inside the sapwood of trees.

    PubMed

    del Hierro, Andrés Miguel; Kronberger, Winfried; Hietz, Peter; Offenthaler, Ivo; Richter, Hanno

    2002-03-01

    Research into the short-term fluctuations of oxygen concentrations in tree stems has been hampered by the difficulty of measuring oxygen inside tissues. A new method, which is based on fluorescence quenching of a ruthenium complex in the presence of oxygen, has been applied to measure changes of oxygen concentration in the sapwood of trees. During a field day-course oxygen increased with the radiation load and fell during the night (in Fagus orientalis from 20.3% in the afternoon to 17.5% in the morning next day). In a greenhouse experiment the sapwood oxygen concentration of Laurus nobilis could be influenced by flooding the root system. The very fast response, high resolution (better than 0.1%), easy calibration, and dependence only on oxygen and temperature make the technique well suited for measurements of oxygen concentrations in the sapwood.