Science.gov

Sample records for accurate experimental determination

  1. Determining accurate distances to nearby galaxies

    NASA Astrophysics Data System (ADS)

    Bonanos, Alceste Zoe

    2005-11-01

    Determining accurate distances to nearby or distant galaxies is a very simple conceptually, yet complicated in practice, task. Presently, distances to nearby galaxies are only known to an accuracy of 10-15%. The current anchor galaxy of the extragalactic distance scale is the Large Magellanic Cloud, which has large (10-15%) systematic uncertainties associated with it, because of its morphology, its non-uniform reddening and the unknown metallicity dependence of the Cepheid period-luminosity relation. This work aims to determine accurate distances to some nearby galaxies, and subsequently help reduce the error in the extragalactic distance scale and the Hubble constant H 0 . In particular, this work presents the first distance determination of the DIRECT Project to M33 with detached eclipsing binaries. DIRECT aims to obtain a new anchor galaxy for the extragalactic distance scale by measuring direct, accurate (to 5%) distances to two Local Group galaxies, M31 and M33, with detached eclipsing binaries. It involves a massive variability survey of these galaxies and subsequent photometric and spectroscopic follow-up of the detached binaries discovered. In this work, I also present a catalog of variable stars discovered in one of the DIRECT fields, M31Y, which includes 41 eclipsing binaries. Additionally, we derive the distance to the Draco Dwarf Spheroidal galaxy, with ~100 RR Lyrae found in our first CCD variability study of this galaxy. A "hybrid" method of discovering Cepheids with ground-based telescopes is described next. It involves applying the image subtraction technique on the images obtained from ground-based telescopes and then following them up with the Hubble Space Telescope to derive Cepheid period-luminosity distances. By re-analyzing ESO Very Large Telescope data on M83 (NGC 5236), we demonstrate that this method is much more powerful for detecting variability, especially in crowded fields. I finally present photometry for the Wolf-Rayet binary WR 20a

  2. Accurate attitude determination of the LACE satellite

    NASA Technical Reports Server (NTRS)

    Miglin, M. F.; Campion, R. E.; Lemos, P. J.; Tran, T.

    1993-01-01

    The Low-power Atmospheric Compensation Experiment (LACE) satellite, launched in February 1990 by the Naval Research Laboratory, uses a magnetic damper on a gravity gradient boom and a momentum wheel with its axis perpendicular to the plane of the orbit to stabilize and maintain its attitude. Satellite attitude is determined using three types of sensors: a conical Earth scanner, a set of sun sensors, and a magnetometer. The Ultraviolet Plume Instrument (UVPI), on board LACE, consists of two intensified CCD cameras and a gimbal led pointing mirror. The primary purpose of the UVPI is to image rocket plumes from space in the ultraviolet and visible wavelengths. Secondary objectives include imaging stars, atmospheric phenomena, and ground targets. The problem facing the UVPI experimenters is that the sensitivity of the LACF satellite attitude sensors is not always adequate to correctly point the UVPI cameras. Our solution is to point the UVPI cameras at known targets and use the information thus gained to improve attitude measurements. This paper describes the three methods developed to determine improved attitude values using the UVPI for both real-time operations and post observation analysis.

  3. On accurate determination of contact angle

    NASA Technical Reports Server (NTRS)

    Concus, P.; Finn, R.

    1992-01-01

    Methods are proposed that exploit a microgravity environment to obtain highly accurate measurement of contact angle. These methods, which are based on our earlier mathematical results, do not require detailed measurement of a liquid free-surface, as they incorporate discontinuous or nearly-discontinuous behavior of the liquid bulk in certain container geometries. Physical testing is planned in the forthcoming IML-2 space flight and in related preparatory ground-based experiments.

  4. 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%.

  5. Accurate determination of serum ASAT isoenzymes.

    PubMed

    Konttinen, A; Ojala, K

    1978-01-01

    An improved electrophoretic modification for measuring aspartate aminotransferase (ASAT) isoenzymes is presented. This method fulfils the clinical requirements for sensitivity and allows the detection of 1 U/l mitochondria ASAT activity at 25 degree C. The procedure is relatively simple, requiring about one hour for a series of 8 determinations. Mitochondrial ASAT activity was found in all patients suffering from acute myocardial infarction pathological activity was observed for several days longer than that of total serum ASAT enzyme. None of the 25 healthy people studied had mitochondrial ASAT in their serum.

  6. Accurate Method for Determining Adhesion of Cantilever Beams

    SciTech Connect

    Michalske, T.A.; de Boer, M.P.

    1999-01-08

    Using surface micromachined samples, we demonstrate the accurate measurement of cantilever beam adhesion by using test structures which are adhered over long attachment lengths. We show that this configuration has a deep energy well, such that a fracture equilibrium is easily reached. When compared to the commonly used method of determining the shortest attached beam, the present method is much less sensitive to variations in surface topography or to details of capillary drying.

  7. Fast and accurate automated cell boundary determination for fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Arce, Stephen Hugo; Wu, Pei-Hsun; Tseng, Yiider

    2013-07-01

    Detailed measurement of cell phenotype information from digital fluorescence images has the potential to greatly advance biomedicine in various disciplines such as patient diagnostics or drug screening. Yet, the complexity of cell conformations presents a major barrier preventing effective determination of cell boundaries, and introduces measurement error that propagates throughout subsequent assessment of cellular parameters and statistical analysis. State-of-the-art image segmentation techniques that require user-interaction, prolonged computation time and specialized training cannot adequately provide the support for high content platforms, which often sacrifice resolution to foster the speedy collection of massive amounts of cellular data. This work introduces a strategy that allows us to rapidly obtain accurate cell boundaries from digital fluorescent images in an automated format. Hence, this new method has broad applicability to promote biotechnology.

  8. Ad hoc methods for accurate determination of Bader's atomic boundary

    NASA Astrophysics Data System (ADS)

    Polestshuk, Pavel M.

    2013-08-01

    In addition to the recently published triangulation method [P. M. Polestshuk, J. Comput. Chem. 34, 206 (2013)], 10.1002/jcc.23121, two new highly accurate approaches, ZFSX and SINTY, for the integration over an atomic region covered by a zero-flux surface (zfs) were developed and efficiently interfaced into the TWOE program. ZFSX method was realized as three independent modules (ZFSX-1, ZFSX-3, and ZFSX-5) handling interatomic surfaces of a different complexity. Details of algorithmic implementation of ZFSX and SINTY are discussed. A special attention to an extended analysis of errors in calculations of atomic properties is paid. It was shown that uncertainties in zfs determination caused by ZFSX and SINTY approaches contribute negligibly (less than 10-6 a.u.) to the total atomic integration errors. Moreover, the new methods are able to evaluate atomic integrals with a reasonable time and can be universally applied for the systems of any complexity. It is suggested, therefore, that ZFSX and SINTY can be regarded as benchmark methods for the computation of any Quantum Theory of Atoms in Molecules atomic property.

  9. Ad hoc methods for accurate determination of Bader's atomic boundary.

    PubMed

    Polestshuk, Pavel M

    2013-08-07

    In addition to the recently published triangulation method [P. M. Polestshuk, J. Comput. Chem. 34, 206 (2013)], two new highly accurate approaches, ZFSX and SINTY, for the integration over an atomic region covered by a zero-flux surface (zfs) were developed and efficiently interfaced into the TWOE program. ZFSX method was realized as three independent modules (ZFSX-1, ZFSX-3, and ZFSX-5) handling interatomic surfaces of a different complexity. Details of algorithmic implementation of ZFSX and SINTY are discussed. A special attention to an extended analysis of errors in calculations of atomic properties is paid. It was shown that uncertainties in zfs determination caused by ZFSX and SINTY approaches contribute negligibly (less than 10(-6) a.u.) to the total atomic integration errors. Moreover, the new methods are able to evaluate atomic integrals with a reasonable time and can be universally applied for the systems of any complexity. It is suggested, therefore, that ZFSX and SINTY can be regarded as benchmark methods for the computation of any Quantum Theory of Atoms in Molecules atomic property.

  10. 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

  11. Experimental Determination of Ramsey Numbers

    NASA Astrophysics Data System (ADS)

    Bian, Zhengbing; Chudak, Fabian; Macready, William G.; Clark, Lane; Gaitan, Frank

    2013-09-01

    Ramsey theory is a highly active research area in mathematics that studies the emergence of order in large disordered structures. Ramsey numbers mark the threshold at which order first appears and are extremely difficult to calculate due to their explosive rate of growth. Recently, an algorithm that can be implemented using adiabatic quantum evolution has been proposed that calculates the two-color Ramsey numbers R(m,n). Here we present results of an experimental implementation of this algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(m,2) for 4≤m≤8. The R(8,2) computation used 84 qubits of which 28 were computational qubits. This computation is the largest experimental implementation of a scientifically meaningful adiabatic evolution algorithm that has been done to date.

  12. Experimental determination of Ramsey numbers.

    PubMed

    Bian, Zhengbing; Chudak, Fabian; Macready, William G; Clark, Lane; Gaitan, Frank

    2013-09-27

    Ramsey theory is a highly active research area in mathematics that studies the emergence of order in large disordered structures. Ramsey numbers mark the threshold at which order first appears and are extremely difficult to calculate due to their explosive rate of growth. Recently, an algorithm that can be implemented using adiabatic quantum evolution has been proposed that calculates the two-color Ramsey numbers R(m,n). Here we present results of an experimental implementation of this algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(m,2) for 4≤m≤8. The R(8,2) computation used 84 qubits of which 28 were computational qubits. This computation is the largest experimental implementation of a scientifically meaningful adiabatic evolution algorithm that has been done to date.

  13. Accurate determination of membrane dynamics with line-scan FCS.

    PubMed

    Ries, Jonas; Chiantia, Salvatore; Schwille, Petra

    2009-03-04

    Here we present an efficient implementation of line-scan fluorescence correlation spectroscopy (i.e., one-dimensional spatio-temporal image correlation spectroscopy) using a commercial laser scanning microscope, which allows the accurate measurement of diffusion coefficients and concentrations in biological lipid membranes within seconds. Line-scan fluorescence correlation spectroscopy is a calibration-free technique. Therefore, it is insensitive to optical artifacts, saturation, or incorrect positioning of the laser focus. In addition, it is virtually unaffected by photobleaching. Correction schemes for residual inhomogeneities and depletion of fluorophores due to photobleaching extend the applicability of line-scan fluorescence correlation spectroscopy to more demanding systems. This technique enabled us to measure accurate diffusion coefficients and partition coefficients of fluorescent lipids in phase-separating supported bilayers of three commonly used raft-mimicking compositions. Furthermore, we probed the temperature dependence of the diffusion coefficient in several model membranes, and in human embryonic kidney cell membranes not affected by temperature-induced optical aberrations.

  14. Determination of sockage for accurate rough rice quality assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of dockage of freshly harvested rice is crucial for precise development of a universal rice shrinking chart. The objectives of this research were to determine the effect of different factors, including rice variety, farm location, harvest moisture and time, drying, dropping, weather ev...

  15. Accurate determination of heteroclinic orbits in chaotic dynamical systems

    NASA Astrophysics Data System (ADS)

    Li, Jizhou; Tomsovic, Steven

    2017-03-01

    Accurate calculation of heteroclinic and homoclinic orbits can be of significant importance in some classes of dynamical system problems. Yet for very strongly chaotic systems initial deviations from a true orbit will be magnified by a large exponential rate making direct computational methods fail quickly. In this paper, a method is developed that avoids direct calculation of the orbit by making use of the well-known stability property of the invariant unstable and stable manifolds. Under an area-preserving map, this property assures that any initial deviation from the stable (unstable) manifold collapses onto them under inverse (forward) iterations of the map. Using a set of judiciously chosen auxiliary points on the manifolds, long orbit segments can be calculated using the stable and unstable manifold intersections of the heteroclinic (homoclinic) tangle. Detailed calculations using the example of the kicked rotor are provided along with verification of the relation between action differences and certain areas bounded by the manifolds.

  16. Efficient determination of accurate atomic polarizabilities for polarizeable embedding calculations

    PubMed Central

    Schröder, Heiner

    2016-01-01

    We evaluate embedding potentials, obtained via various methods, used for polarizable embedding computations of excitation energies of para‐nitroaniline in water and organic solvents as well as of the green fluorescent protein. We found that isotropic polarizabilities derived from DFTD3 dispersion coefficients correlate well with those obtained via the LoProp method. We show that these polarizabilities in conjunction with appropriately derived point charges are in good agreement with calculations employing static multipole moments up to quadrupoles and anisotropic polarizabilities for both computed systems. The (partial) use of these easily‐accessible parameters drastically reduces the computational effort to obtain accurate embedding potentials especially for proteins. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:27317509

  17. Trace hydrazines in aqueous solutions accurately determined by gas chromatography

    NASA Technical Reports Server (NTRS)

    Welz, E. A., Jr.

    1967-01-01

    Trace amounts of hydrazines in aqueous solutions can be determined by using polythyleneimine /PEI/ in conjunction with the gas chromatographic column. The PEI specifically retains water without altering the separability or elution order of the hydrazine and associated constituents.

  18. Apparatus enables accurate determination of alkali oxides in alkali metals

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.; Gahn, R. F.; Graab, J. W.; Maple, W. E.; Rosenblum, L.

    1966-01-01

    Evacuated apparatus determines the alkali oxide content of an alkali metal by separating the metal from the oxide by amalgamation with mercury. The apparatus prevents oxygen and moisture from inadvertently entering the system during the sampling and analytical procedure.

  19. Accurate Determination of the Volume of an Irregular Helium Balloon

    NASA Astrophysics Data System (ADS)

    Blumenthal, Jack; Bradvica, Rafaela; Karl, Katherine

    2013-02-01

    In a recent paper, Zable described an experiment with a near-spherical balloon filled with impure helium. Measuring the temperature and the pressure inside and outside the balloon, the lift of the balloon, and the mass of the balloon materials, he described how to use the ideal gas laws and Archimedes' principal to compute the average molecular mass and density of the impure helium. This experiment required that the volume of the near-spherical balloon be determined by some approach, such as measuring the girth. The accuracy of the experiment was largely determined by the balloon volume, which had a reported uncertainty of about 4%.

  20. Accurate determination of rates from non-uniformly sampled relaxation data.

    PubMed

    Stetz, Matthew A; Wand, A Joshua

    2016-08-01

    The application of non-uniform sampling (NUS) to relaxation experiments traditionally used to characterize the fast internal motion of proteins is quantitatively examined. Experimentally acquired Poisson-gap sampled data reconstructed with iterative soft thresholding are compared to regular sequentially sampled (RSS) data. Using ubiquitin as a model system, it is shown that 25 % sampling is sufficient for the determination of quantitatively accurate relaxation rates. When the sampling density is fixed at 25 %, the accuracy of rates is shown to increase sharply with the total number of sampled points until eventually converging near the inherent reproducibility of the experiment. Perhaps contrary to some expectations, it is found that accurate peak height reconstruction is not required for the determination of accurate rates. Instead, inaccuracies in rates arise from inconsistencies in reconstruction across the relaxation series that primarily manifest as a non-linearity in the recovered peak height. This indicates that the performance of an NUS relaxation experiment cannot be predicted from comparison of peak heights using a single RSS reference spectrum. The generality of these findings was assessed using three alternative reconstruction algorithms, eight different relaxation measurements, and three additional proteins that exhibit varying degrees of spectral complexity. From these data, it is revealed that non-linearity in peak height reconstruction across the relaxation series is strongly correlated with errors in NUS-derived relaxation rates. Importantly, it is shown that this correlation can be exploited to reliably predict the performance of an NUS-relaxation experiment by using three or more RSS reference planes from the relaxation series. The RSS reference time points can also serve to provide estimates of the uncertainty of the sampled intensity, which for a typical relaxation times series incurs no penalty in total acquisition time.

  1. Accurate determination of the vapor pressure of potassium using optical absorption

    NASA Technical Reports Server (NTRS)

    Shirinzadeh, B.; Wang, C. C.

    1983-01-01

    The vapor pressure of potassium has been measured in absorption using a CW tunable laser and calibrated against the accurate radiative lifetime of the 4s-4p doublet of potassium. An accurate value of 20,850 + or - 30 cal/mol for the heat of vaporization (from the liquid phase) at the melting point was determined.

  2. Accurate Determination of the Frequency Response Function of Submerged and Confined Structures by Using PZT-Patches†.

    PubMed

    Presas, Alexandre; Valentin, David; Egusquiza, Eduard; Valero, Carme; Egusquiza, Mònica; Bossio, Matias

    2017-03-22

    To accurately determine the dynamic response of a structure is of relevant interest in many engineering applications. Particularly, it is of paramount importance to determine the Frequency Response Function (FRF) for structures subjected to dynamic loads in order to avoid resonance and fatigue problems that can drastically reduce their useful life. One challenging case is the experimental determination of the FRF of submerged and confined structures, such as hydraulic turbines, which are greatly affected by dynamic problems as reported in many cases in the past. The utilization of classical and calibrated exciters such as instrumented hammers or shakers to determine the FRF in such structures can be very complex due to the confinement of the structure and because their use can disturb the boundary conditions affecting the experimental results. For such cases, Piezoelectric Patches (PZTs), which are very light, thin and small, could be a very good option. Nevertheless, the main drawback of these exciters is that the calibration as dynamic force transducers (relationship voltage/force) has not been successfully obtained in the past. Therefore, in this paper, a method to accurately determine the FRF of submerged and confined structures by using PZTs is developed and validated. The method consists of experimentally determining some characteristic parameters that define the FRF, with an uncalibrated PZT exciting the structure. These parameters, which have been experimentally determined, are then introduced in a validated numerical model of the tested structure. In this way, the FRF of the structure can be estimated with good accuracy. With respect to previous studies, where only the natural frequencies and mode shapes were considered, this paper discuss and experimentally proves the best excitation characteristic to obtain also the damping ratios and proposes a procedure to fully determine the FRF. The method proposed here has been validated for the structure vibrating

  3. Accurate Determination of the Frequency Response Function of Submerged and Confined Structures by Using PZT-Patches †

    PubMed Central

    Presas, Alexandre; Valentin, David; Egusquiza, Eduard; Valero, Carme; Egusquiza, Mònica; Bossio, Matias

    2017-01-01

    To accurately determine the dynamic response of a structure is of relevant interest in many engineering applications. Particularly, it is of paramount importance to determine the Frequency Response Function (FRF) for structures subjected to dynamic loads in order to avoid resonance and fatigue problems that can drastically reduce their useful life. One challenging case is the experimental determination of the FRF of submerged and confined structures, such as hydraulic turbines, which are greatly affected by dynamic problems as reported in many cases in the past. The utilization of classical and calibrated exciters such as instrumented hammers or shakers to determine the FRF in such structures can be very complex due to the confinement of the structure and because their use can disturb the boundary conditions affecting the experimental results. For such cases, Piezoelectric Patches (PZTs), which are very light, thin and small, could be a very good option. Nevertheless, the main drawback of these exciters is that the calibration as dynamic force transducers (relationship voltage/force) has not been successfully obtained in the past. Therefore, in this paper, a method to accurately determine the FRF of submerged and confined structures by using PZTs is developed and validated. The method consists of experimentally determining some characteristic parameters that define the FRF, with an uncalibrated PZT exciting the structure. These parameters, which have been experimentally determined, are then introduced in a validated numerical model of the tested structure. In this way, the FRF of the structure can be estimated with good accuracy. With respect to previous studies, where only the natural frequencies and mode shapes were considered, this paper discuss and experimentally proves the best excitation characteristic to obtain also the damping ratios and proposes a procedure to fully determine the FRF. The method proposed here has been validated for the structure vibrating

  4. Diagnostic methodology is critical for accurately determining the prevalence of ichthyophonus infections in wild fish populations

    USGS Publications Warehouse

    Kocan, R.; Dolan, H.; Hershberger, P.

    2011-01-01

    Several different techniques have been employed to detect and identify Ichthyophonus spp. in infected fish hosts; these include macroscopic observation, microscopic examination of tissue squashes, histological evaluation, in vitro culture, and molecular techniques. Examination of the peer-reviewed literature revealed that when more than 1 diagnostic method is used, they often result in significantly different results; for example, when in vitro culture was used to identify infected trout in an experimentally exposed population, 98.7% of infected trout were detected, but when standard histology was used to confirm known infected tissues from wild salmon, it detected ~50% of low-intensity infections and ~85% of high-intensity infections. Other studies on different species reported similar differences. When we examined a possible mechanism to explain the disparity between different diagnostic techniques, we observed non-random distribution of the parasite in 3-dimensionally visualized tissue sections from infected hosts, thus providing a possible explanation for the different sensitivities of commonly used diagnostic techniques. Based on experimental evidence and a review of the peer-reviewed literature, we have concluded that in vitro culture is currently the most accurate diagnostic technique for determining infection prevalence of Ichthyophonus, particularly when the exposure history of the population is not known.

  5. Experimental and theoretical oscillator strengths of Mg i for accurate abundance analysis

    NASA Astrophysics Data System (ADS)

    Pehlivan Rhodin, A.; Hartman, H.; Nilsson, H.; Jönsson, P.

    2017-02-01

    Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the α-element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between different evolution models. Aims: We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the oscillator strengths (f-values) of Mg i lines and to create a complete set of accurate atomic data, particularly for the near-IR region. Methods: We derived oscillator strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K. Results: This project provides a set of experimental and theoretical oscillator strengths. We derived 34 experimental oscillator strengths. Except from the Mg i optical triplet lines (3p 3P°0,1,2-4s 3S1), these oscillator strengths are measured for the first time. The theoretical oscillator strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of oscillator strengths, gf, with uncertainties as small as 5%. The new values of the Mg i optical triplet line (3p 3P°0,1,2-4s 3S1) oscillator strength values are 0.08 dex larger than the previous measurements.

  6. Accurate Determination of the Boltzmann Constant by Doppler Spectroscopy Towards a New Definition of the Kelvin

    NASA Astrophysics Data System (ADS)

    Sow, P. L. T.; Merji, S.; Tokunaga, S. K.; Lemarchand, C.; Triki, M.; Borde, C.; Chardonnet, C.; Darquie, B.; Daussy, C.

    2013-06-01

    Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 μm enables a determination of the Boltzmann constant k_{{B}}. We report on our latest measurements. The main systematic effects, including the temperature control, will be discussed and an error budget will be presented in which the global uncertainty on systematic effects is at the level of a few ppm. This is valid provided that data is recorded under the optimized experimental conditions determined by the studies of systematic effects and provided that spectra are fitted to the speed-dependent Voigt profile, identified as the most suitable lineshape for our measurements. A determination of k_{{B}} by Doppler spectroscopy with a combined uncertainty of a few ppm is within reach. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of k_{{B}} determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the Kelvin by fixing k_{{B}}, an exciting prospect considering the upcoming redefinition of the International System of Units (SI). C. Lemarchand, M. Triki, B. Darquié, C. J. Bordé, C. Chardonnet and C. Daussy, New J. Phys. 13, 073028 (2011). M. Triki, C. Lemarchand, B. Darquié, P. L. T. Sow, V. Roncin, C. Chardonnet, and C. Daussy, Phys. Rev. A 85, 062510 (2012).

  7. Fluorescence polarization immunoassays for rapid, accurate, and sensitive determination of mycotoxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analytical methods for the determination of mycotoxins in foods are commonly based on chromatographic techniques (GC, HPLC or LC-MS). Although these methods permit a sensitive and accurate determination of the analyte, they require skilled personnel and are time-consuming, expensive, and unsuitable ...

  8. Significance of accurate diffraction corrections for the second harmonic wave in determining the acoustic nonlinearity parameter

    SciTech Connect

    Jeong, Hyunjo; Zhang, Shuzeng; Li, Xiongbing; Barnard, Dan

    2015-09-15

    The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α{sub 2} ≃ 2α{sub 1}.

  9. Experimental Determination of Gas Phase Thermodynamic Properties of Bimolecular Complexes

    NASA Astrophysics Data System (ADS)

    Hansen, Anne S.; Maroun, Zeina; Mackeprang, Kasper; Kjaergaard, Henrik G.

    2016-06-01

    Accurate determination of the atmospheric abundance of hydrogen bound bimolecular complexes is necessary, as hydrogen bonds are partly responsible for the formation and growth of aerosol particles. The abundance of a complex is related to the Gibbs free energy of complex formation (Δ G), which is often obtained from quantum chemical calculations that rely on calculated values of the enthalpy (Δ H) and entropy (Δ S) of complex formation. However, calculations of Δ H and in particular Δ S are associated with large uncertainties, and accurate experimental values are therefore crucial for theoretical benchmarking studies. Infrared measurements of gas phase hydrogen bound complexes were performed in the 300 to 373 K range, and lead to a purely experimental determination of Δ H using the van't Hoff equation. Equilibrium constants were determined by combining an experimental and calculated OH-stretching intensity, from which values of Δ G and hence Δ S could be determined. Thus we can determine Δ G, Δ H and Δ S for a bimolecular complex. We find that in the 300 to 373 K temperature range the determined Δ H and Δ S values are independent of temperature.

  10. Accurate rotational constants for linear interstellar carbon chains: achieving experimental accuracy

    NASA Astrophysics Data System (ADS)

    Etim, Emmanuel E.; Arunan, Elangannan

    2017-01-01

    Linear carbon chain molecular species remain the dominant theme in interstellar chemistry. Their continuous astronomical observation depends on the availability of accurate spectroscopic parameters. Accurate rotational constants are reported for hundreds of molecular species of astrophysical, spectroscopy and chemical interests from the different linear carbon chains; C_{{n}}H, C_{{n}}H-, C_{{n}}N, C_{{n}}N-, C_{{n}}O, C_{{n}}S, HC_{{n}}S, C_{{n}}Si, CH3(CC)_{{n}}H, HC_{{n}}N, DC_{2{n}+1}N, HC_{2{n}}NC, and CH3(C≡C)_{{n}}CN using three to four moments of inertia calculated from the experimental rotational constants coupled with those obtained from the optimized geometries at the Hartree Fock level. The calculated rotational constants are obtained from the corrected moments of inertia at the Hartfree Fock geometries. The calculated rotational constants show accuracy of few kHz below irrespective of the chain length and terminating groups. The obtained accuracy of few kHz places these rotational constants as excellent tools for both astronomical and laboratory detection of these molecular species of astrophysical interest. From the numerous unidentified lines from different astronomical surveys, transitions corresponding to known and new linear carbon chains could be found using these rotational constants. The astrophysical, spectroscopic and chemical implications of these results are discussed.

  11. Identification and Evaluation of Reference Genes for Accurate Transcription Normalization in Safflower under Different Experimental Conditions

    PubMed Central

    Li, Dandan; Hu, Bo; Wang, Qing; Liu, Hongchang; Pan, Feng; Wu, Wei

    2015-01-01

    Safflower (Carthamus tinctorius L.) has received a significant amount of attention as a medicinal plant and oilseed crop. Gene expression studies provide a theoretical molecular biology foundation for improving new traits and developing new cultivars. Real-time quantitative PCR (RT-qPCR) has become a crucial approach for gene expression analysis. In addition, appropriate reference genes (RGs) are essential for accurate and rapid relative quantification analysis of gene expression. In this study, fifteen candidate RGs involved in multiple metabolic pathways of plants were finally selected and validated under different experimental treatments, at different seed development stages and in different cultivars and tissues for real-time PCR experiments. These genes were ABCS, 60SRPL10, RANBP1, UBCL, MFC, UBCE2, EIF5A, COA, EF1-β, EF1, GAPDH, ATPS, MBF1, GTPB and GST. The suitability evaluation was executed by the geNorm and NormFinder programs. Overall, EF1, UBCE2, EIF5A, ATPS and 60SRPL10 were the most stable genes, and MBF1, as well as MFC, were the most unstable genes by geNorm and NormFinder software in all experimental samples. To verify the validation of RGs selected by the two programs, the expression analysis of 7 CtFAD2 genes in safflower seeds at different developmental stages under cold stress was executed using different RGs in RT-qPCR experiments for normalization. The results showed similar expression patterns when the most stable RGs selected by geNorm or NormFinder software were used. However, the differences were detected using the most unstable reference genes. The most stable combination of genes selected in this study will help to achieve more accurate and reliable results in a wide variety of samples in safflower. PMID:26457898

  12. On canonical cylinder sections for accurate determination of contact angle in microgravity

    NASA Technical Reports Server (NTRS)

    Concus, Paul; Finn, Robert; Zabihi, Farhad

    1992-01-01

    Large shifts of liquid arising from small changes in certain container shapes in zero gravity can be used as a basis for accurately determining contact angle. Canonical geometries for this purpose, recently developed mathematically, are investigated here computationally. It is found that the desired nearly-discontinuous behavior can be obtained and that the shifts of liquid have sufficient volume to be readily observed.

  13. Accurate ampacity determination: Temperature-Sag Model for operational real time ratings

    SciTech Connect

    Seppa, T.O.

    1995-07-01

    This report presents a method for determining transmission line ratings based on the relationship between the conductor`s temperature and its sag. The method is based on the Ruling Span principle and the use of transmission line tension monitoring systems. The report also presents a method of accurately calibrating the final sag of the conductor and determining the actual Ruling Span length of the line sections between deadend structures. Main error sources for two other real time methods are also examined.

  14. Experimental determination of thermodynamic equilibrium in biocatalytic transamination.

    PubMed

    Tufvesson, Pär; Jensen, Jacob S; Kroutil, Wolfgang; Woodley, John M

    2012-08-01

    The equilibrium constant is a critical parameter for making rational design choices in biocatalytic transamination for the synthesis of chiral amines. However, very few reports are available in the scientific literature determining the equilibrium constant (K) for the transamination of ketones. Various methods for determining (or estimating) equilibrium have previously been suggested, both experimental as well as computational (based on group contribution methods). However, none of these were found suitable for determining the equilibrium constant for the transamination of ketones. Therefore, in this communication we suggest a simple experimental methodology which we hope will stimulate more accurate determination of thermodynamic equilibria when reporting the results of transaminase-catalyzed reactions in order to increase understanding of the relationship between substrate and product molecular structure on reaction thermodynamics.

  15. Accurate and precise determination of isotopic ratios by MC-ICP-MS: a review.

    PubMed

    Yang, Lu

    2009-01-01

    For many decades the accurate and precise determination of isotope ratios has remained a very strong interest to many researchers due to its important applications in earth, environmental, biological, archeological, and medical sciences. Traditionally, thermal ionization mass spectrometry (TIMS) has been the technique of choice for achieving the highest accuracy and precision. However, recent developments in multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) have brought a new dimension to this field. In addition to its simple and robust sample introduction, high sample throughput, and high mass resolution, the flat-topped peaks generated by this technique provide for accurate and precise determination of isotope ratios with precision reaching 0.001%, comparable to that achieved with TIMS. These features, in combination with the ability of the ICP source to ionize nearly all elements in the periodic table, have resulted in an increased use of MC-ICP-MS for such measurements in various sample matrices. To determine accurate and precise isotope ratios with MC-ICP-MS, utmost care must be exercised during sample preparation, optimization of the instrument, and mass bias corrections. Unfortunately, there are inconsistencies and errors evident in many MC-ICP-MS publications, including errors in mass bias correction models. This review examines "state-of-the-art" methodologies presented in the literature for achievement of precise and accurate determinations of isotope ratios by MC-ICP-MS. Some general rules for such accurate and precise measurements are suggested, and calculations of combined uncertainty of the data using a few common mass bias correction models are outlined.

  16. A fast and accurate algorithm for high-frequency trans-ionospheric path length determination

    NASA Astrophysics Data System (ADS)

    Wijaya, Dudy D.

    2015-12-01

    This paper presents a fast and accurate algorithm for high-frequency trans-ionospheric path length determination. The algorithm is merely based on the solution of the Eikonal equation that is solved using the conformal theory of refraction. The main advantages of the algorithm are summarized as follows. First, the algorithm can determine the optical path length without iteratively adjusting both elevation and azimuth angles and, hence, the computational time can be reduced. Second, for the same elevation and azimuth angles, the algorithm can simultaneously determine the phase and group of both ordinary and extra-ordinary optical path lengths for different frequencies. Results from numerical simulations show that the computational time required by the proposed algorithm to accurately determine 8 different optical path lengths is almost 17 times faster than that required by a 3D ionospheric ray-tracing algorithm. It is found that the computational time to determine multiple optical path lengths is the same with that for determining a single optical path length. It is also found that the proposed algorithm is capable of determining the optical path lengths with millimeter level of accuracies, if the magnitude of the squared ratio of the plasma frequency to the transmitted frequency is less than 1.33× 10^{-3}, and hence the proposed algorithm is applicable for geodetic applications.

  17. Toward Accurate On-Ground Attitude Determination for the Gaia Spacecraft

    NASA Astrophysics Data System (ADS)

    Samaan, Malak A.

    2010-03-01

    The work presented in this paper concerns the accurate On-Ground Attitude (OGA) reconstruction for the astrometry spacecraft Gaia in the presence of disturbance and of control torques acting on the spacecraft. The reconstruction of the expected environmental torques which influence the spacecraft dynamics will be also investigated. The telemetry data from the spacecraft will include the on-board real-time attitude, which is of order of several arcsec. This raw attitude is the starting point for the further attitude reconstruction. The OGA will use the inputs from the field coordinates of known stars (attitude stars) and also the field coordinate differences of objects on the Sky Mapper (SM) and Astrometric Field (AF) payload instruments to improve this raw attitude. The on-board attitude determination uses a Kalman Filter (KF) to minimize the attitude errors and produce a more accurate attitude estimation than the pure star tracker measurement. Therefore the first approach for the OGA will be an adapted version of KF. Furthermore, we will design a batch least squares algorithm to investigate how to obtain a more accurate OGA estimation. Finally, a comparison between these different attitude determination techniques in terms of accuracy, robustness, speed and memory required will be evaluated in order to choose the best attitude algorithm for the OGA. The expected resulting accuracy for the OGA determination will be on the order of milli-arcsec.

  18. The accurate measurement of second virial coefficients using self-interaction chromatography: experimental considerations.

    PubMed

    Quigley, A; Heng, J Y Y; Liddell, J M; Williams, D R

    2013-11-01

    Measurement of B22, the second virial coefficient, is an important technique for describing the solution behaviour of proteins, especially as it relates to precipitation, aggregation and crystallisation phenomena. This paper describes the best practise for calculating B22 values from self-interaction chromatograms (SIC) for aqueous protein solutions. Detailed analysis of SIC peak shapes for lysozyme shows that non-Gaussian peaks are commonly encountered for SIC, with typical peak asymmetries of 10%. This asymmetry reflects a non-linear chromatographic retention process, in this case heterogeneity of the protein-protein interactions. Therefore, it is important to use the centre of mass calculations for determining accurate retention volumes and thus B22 values. Empirical peak maximum chromatogram analysis, often reported in the literature, can result in errors of up to 50% in B22 values. A methodology is reported here for determining both the mean and the variance in B22 from SIC experiments, includes a correction for normal longitudinal peak broadening. The variance in B22 due to chemical effects is quantified statistically and is a measure of the heterogeneity of protein-protein interactions in solution. In the case of lysozyme, a wide range of B22 values are measured which can vary significantly from the average B22 values.

  19. Rapid and accurate determination of the lignin content of lignocellulosic biomass by solid-state NMR.

    PubMed

    Fu, Li; McCallum, Scott A; Miao, Jianjun; Hart, Courtney; Tudryn, Gregory J; Zhang, Fuming; Linhardt, Robert J

    2015-02-01

    Biofuels and biomaterials, produced from lignocellulosic feedstock, require facile access to cellulose and hemicellulose to be competitive with petroleum processing and sugar-based fermentation. Physical-chemical barriers resulting from lignin complicates the hydrolysis biomass into fermentable sugars. Thus, the amount of lignin within a substrate is critical in determining biomass processing. The application of (13)C cross-polarization, magic-angle spinning, and solid-state nuclear magnetic resonance for the direct quantification of lignin content in biomass is examined. Using a standard curve constructed from pristine lignin and cellulose, the lignin content of a biomass sample is accurately determined through direct measurement without chemical or enzymatic pre-treatment.

  20. Accurate determination of aldehydes in amine catalysts or amines by 2,4-dinitrophenylhydrazine derivatization.

    PubMed

    Barman, Bhajendra N

    2014-01-31

    Carbonyl compounds, specifically aldehydes, present in amine catalysts or amines are determined by reversed-phase liquid chromatography using ultraviolet detection of their corresponding 2,4-dinitrophenylhydrazones. The primary focus has been to establish optimum conditions for determining aldehydes accurately because these add exposure concerns when the amine catalysts are used to manufacture polyurethane products. Concentrations of aldehydes determined by this method are found to vary with the pH of the aqueous amine solution and the derivatization time, the latter being problematic when the derivatization reaction proceeds slowly and not to completion in neutral and basic media. Accurate determination of aldehydes in amines through derivatization can be carried out at an effective solution pH of about 2 and with derivatization time of 20min. Hydrochloric acid has been used for neutralization of an amine. For complete derivatization, it is essential to protonate all nitrogen atoms in the amine. An approach for the determination of an adequate amount of acid needed for complete derivatization has been described. Several 0.2M buffer solutions varying in pH from 4 to 8 have also been used to make amine solutions for carrying out derivatization of aldehydes. These solutions have effective pHs of 10 or higher and provide much lower aldehyde concentrations compared to their true values. Mechanisms for the formation of 2,4-dinitrophenylhydrazones in both acidic and basic media are discussed.

  1. An experimental device for accurate ultrasounds measurements in liquid foods at high pressure

    NASA Astrophysics Data System (ADS)

    Hidalgo-Baltasar, E.; Taravillo, M.; Baonza, V. G.; Sanz, P. D.; Guignon, B.

    2012-12-01

    The use of high hydrostatic pressure to ensure safe and high-quality product has markedly increased in the food industry during the last decade. Ultrasonic sensors can be employed to control such processes in an equivalent way as they are currently used in processes carried out at room pressure. However, their installation, calibration and use are particularly challenging in the context of a high pressure environment. Besides, data about acoustic properties of food under pressure and even for water are quite scarce in the pressure range of interest for food treatment (namely, above 200 MPa). The objective of this work was to establish a methodology to determine the speed of sound in foods under pressure. An ultrasonic sensor using the multiple reflections method was adapted to a lab-scale HHP equipment to determine the speed of sound in water between 253.15 and 348.15 K, and at pressures up to 700 MPa. The experimental speed-of-sound data were compared to the data calculated from the equation of state of water (IAPWS-95 formulation). From this analysis, the way to calibrate cell path was validated. After this calibration procedure, the speed of sound could be determined in liquid foods by using this sensor with a relative uncertainty between (0.22 and 0.32) % at a confidence level of 95 % over the whole pressure domain.

  2. Communication: Accurate determination of side-chain torsion angle χ1 in proteins: Phenylalanine residues

    NASA Astrophysics Data System (ADS)

    Suardíaz, R.; Crespo-Otero, R.; Pérez, C.; Fabián, J. San; de la Vega, J. M. García

    2011-02-01

    Quantitative side-chain torsion angle χ1 determinations of phenylalanine residues in Desulfovibrio vulgaris flavodoxin are carried out using exclusively the correlation between the experimental vicinal coupling constants and theoretically determined Karplus equations. Karplus coefficients for nine vicinal coupling related with the torsion angle χ1 were calculated using the B3LYP functional and basis sets of different size. Optimized χ1 angles are in outstanding agreement with those previously reported by employing x ray and NMR measurements.

  3. A powerful test of independent assortment that determines genome-wide significance quickly and accurately

    PubMed Central

    Stewart, W C L; Hager, V R

    2016-01-01

    In the analysis of DNA sequences on related individuals, most methods strive to incorporate as much information as possible, with little or no attention paid to the issue of statistical significance. For example, a modern workstation can easily handle the computations needed to perform a large-scale genome-wide inheritance-by-descent (IBD) scan, but accurate assessment of the significance of that scan is often hindered by inaccurate approximations and computationally intensive simulation. To address these issues, we developed gLOD—a test of co-segregation that, for large samples, models chromosome-specific IBD statistics as a collection of stationary Gaussian processes. With this simple model, the parametric bootstrap yields an accurate and rapid assessment of significance—the genome-wide corrected P-value. Furthermore, we show that (i) under the null hypothesis, the limiting distribution of the gLOD is the standard Gumbel distribution; (ii) our parametric bootstrap simulator is approximately 40 000 times faster than gene-dropping methods, and it is more powerful than methods that approximate the adjusted P-value; and, (iii) the gLOD has the same statistical power as the widely used maximum Kong and Cox LOD. Thus, our approach gives researchers the ability to determine quickly and accurately the significance of most large-scale IBD scans, which may contain multiple traits, thousands of families and tens of thousands of DNA sequences. PMID:27245422

  4. Accurate bulk density determination of irregularly shaped translucent and opaque aerogels

    NASA Astrophysics Data System (ADS)

    Petkov, M. P.; Jones, S. M.

    2016-05-01

    We present a volumetric method for accurate determination of bulk density of aerogels, calculated from extrapolated weight of the dry pure solid and volume estimates based on the Archimedes' principle of volume displacement, using packed 100 μm-sized monodispersed glass spheres as a "quasi-fluid" media. Hard particle packing theory is invoked to demonstrate the reproducibility of the apparent density of the quasi-fluid. Accuracy rivaling that of the refractive index method is demonstrated for both translucent and opaque aerogels with different absorptive properties, as well as for aerogels with regular and irregular shapes.

  5. Techniques for determining propulsion system forces for accurate high speed vehicle drag measurements in flight

    NASA Technical Reports Server (NTRS)

    Arnaiz, H. H.

    1975-01-01

    As part of a NASA program to evaluate current methods of predicting the performance of large, supersonic airplanes, the drag of the XB-70 airplane was measured accurately in flight at Mach numbers from 0.75 to 2.5. This paper describes the techniques used to determine engine net thrust and the drag forces charged to the propulsion system that were required for the in-flight drag measurements. The accuracy of the measurements and the application of the measurement techniques to aircraft with different propulsion systems are discussed. Examples of results obtained for the XB-70 airplane are presented.

  6. The use of experimental bending tests to more accurate numerical description of TBC damage process

    NASA Astrophysics Data System (ADS)

    Sadowski, T.; Golewski, P.

    2016-04-01

    Thermal barrier coatings (TBCs) have been extensively used in aircraft engines to protect critical engine parts such as blades and combustion chambers, which are exposed to high temperatures and corrosive environment. The blades of turbine engines are additionally exposed to high mechanical loads. These loads are created by the high rotational speed of the rotor (30 000 rot/min), causing the tensile and bending stresses. Therefore, experimental testing of coated samples is necessary in order to determine strength properties of TBCs. Beam samples with dimensions 50×10×2 mm were used in those studies. The TBC system consisted of 150 μm thick bond coat (NiCoCrAlY) and 300 μm thick top coat (YSZ) made by APS (air plasma spray) process. Samples were tested by three-point bending test with various loads. After bending tests, the samples were subjected to microscopic observation to determine the quantity of cracks and their depth. The above mentioned results were used to build numerical model and calibrate material data in Abaqus program. Brittle cracking damage model was applied for the TBC layer, which allows to remove elements after reaching criterion. Surface based cohesive behavior was used to model the delamination which may occur at the boundary between bond coat and top coat.

  7. Accurate orbit determination strategies for the tracking and data relay satellites

    NASA Technical Reports Server (NTRS)

    Oza, D. H.; Bolvin, D. T.; Lorah, J. M.; Lee, T.; Doll, C. E.

    1995-01-01

    The National Aeronautics and Space Administration (NASA) has developed the Tracking and Data Relay Satellite (TDRS) System (TDRSS) for tracking and communications support of low Earth-orbiting satellites. TDRSS has the operational capability of providing 85% coverage for TDRSS-user spacecraft. TDRSS currently consists of five geosynchronous spacecraft and the White Sands Complex (WSC) at White Sands, New Mexico. The Bilateration Ranging Transponder System (BRTS) provides range and Doppler measurements for each TDRS. The ground-based BRTS transponders are tracked as if they were TDRSS-user spacecraft. Since the positions of the BRTS transponders are known, their radiometric tracking measurements can be used to provide a well-determined ephemeris for the TDRS spacecraft. For high-accuracy orbit determination of a TDRSS user, such as the Ocean Topography Experiment (TOPEX)/Poseidon spacecraft, high-accuracy TDRS orbits are required. This paper reports on successive refinements in improved techniques and procedures leading to more accurate TDRS orbit determination strategies using the Goddard Trajectory Determination System (GTDS). These strategies range from the standard operational solution using only the BRTS tracking measurements to a sophisticated iterative process involving several successive simultaneous solutions for multiple TDRSs and a TDRSS-user spacecraft. Results are presented for GTDS-generated TDRS ephemerides produced in simultaneous solutions with the TOPEX/Poseidon spacecraft. Strategies with different user spacecraft, as well as schemes for recovering accurate TDRS orbits following a TDRS maneuver, are also presented. In addition, a comprehensive assessment and evaluation of alternative strategies for TDRS orbit determination, excluding BRTS tracking measurements, are presented.

  8. Rapid and accurate determination of the lignin content of lignocellulosic biomass by solid-state NMR

    PubMed Central

    Fu, Li; McCallum, Scott A.; Miao, Jianjun; Hart, Courtney; Tudryn, Gregory J.; Zhang, Fuming; Linhardt, Robert J.

    2014-01-01

    Biofuels and biomaterials, produced from lignocellulosic feedstock, require facile access to cellulose and hemicellulose to be competitive with petroleum processing and sugar-based fermentation. Physical-chemical barriers resulting from lignin complicates the hydrolysis biomass into fermentable sugars. Thus, the amount of lignin within a substrate is critical in determining biomass processing. The application of 13C cross-polarization, magic-angle spinning, and solid-state nuclear magnetic resonance for the direct quantification of lignin content in biomass is examined. Using a standard curve constructed from pristine lignin and cellulose, the lignin content of a biomass sample is accurately determined through direct measurement without chemical or enzymatic pre-treatment. PMID:25404762

  9. Accurate determination of plasmonic fields in molecular junctions by current rectification at optical frequencies.

    PubMed

    Arielly, Rani; Ofarim, Ayelet; Noy, Gilad; Selzer, Yoram

    2011-07-13

    Current rectification, i.e., induction of dc current by oscillating electromagnetic fields, is demonstrated in molecular junctions at an optical frequency. The magnitude of rectification is used to accurately determine the effective oscillating potentials in the junctions induced by the irradiating laser. Since the gap size of the junctions used in this study is precisely determined by the length of the embedded molecules, the oscillating potential can be used to calculate the plasmonic enhancement of the electromagnetic field in the junctions. With a set of junctions based on alkyl thiolated molecules with identical HOMO-LUMO gap and different lengths, an exponential dependence of the plasmonic field enhancement on gap size is observed.

  10. Accurate determination of the diffusion coefficient of proteins by Fourier analysis with whole column imaging detection.

    PubMed

    Zarabadi, Atefeh S; Pawliszyn, Janusz

    2015-02-17

    Analysis in the frequency domain is considered a powerful tool to elicit precise information from spectroscopic signals. In this study, the Fourier transformation technique is employed to determine the diffusion coefficient (D) of a number of proteins in the frequency domain. Analytical approaches are investigated for determination of D from both experimental and data treatment viewpoints. The diffusion process is modeled to calculate diffusion coefficients based on the Fourier transformation solution to Fick's law equation, and its results are compared to time domain results. The simulations characterize optimum spatial and temporal conditions and demonstrate the noise tolerance of the method. The proposed model is validated by its application for the electropherograms from the diffusion path of a set of proteins. Real-time dynamic scanning is conducted to monitor dispersion by employing whole column imaging detection technology in combination with capillary isoelectric focusing (CIEF) and the imaging plug flow (iPF) experiment. These experimental techniques provide different peak shapes, which are utilized to demonstrate the Fourier transformation ability in extracting diffusion coefficients out of irregular shape signals. Experimental results confirmed that the Fourier transformation procedure substantially enhanced the accuracy of the determined values compared to those obtained in the time domain.

  11. Experimental determination of stator endwall heat transfer

    NASA Technical Reports Server (NTRS)

    Boyle, Robert J.; Russell, Louis M.

    1989-01-01

    Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane possage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Resutls were obtained for Reynolds numbers based on inlet velocity and axial chord between 75,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

  12. Experimental determination of stator endwall heat transfer

    NASA Technical Reports Server (NTRS)

    Boyle, Robert J.; Russell, Louis M.

    1989-01-01

    Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

  13. A fast experimental beam hardening correction method for accurate bone mineral measurements in 3D μCT imaging system.

    PubMed

    Koubar, Khodor; Bekaert, Virgile; Brasse, David; Laquerriere, Patrice

    2015-06-01

    Bone mineral density plays an important role in the determination of bone strength and fracture risks. Consequently, it is very important to obtain accurate bone mineral density measurements. The microcomputerized tomography system provides 3D information about the architectural properties of bone. Quantitative analysis accuracy is decreased by the presence of artefacts in the reconstructed images, mainly due to beam hardening artefacts (such as cupping artefacts). In this paper, we introduced a new beam hardening correction method based on a postreconstruction technique performed with the use of off-line water and bone linearization curves experimentally calculated aiming to take into account the nonhomogeneity in the scanned animal. In order to evaluate the mass correction rate, calibration line has been carried out to convert the reconstructed linear attenuation coefficient into bone masses. The presented correction method was then applied on a multimaterial cylindrical phantom and on mouse skeleton images. Mass correction rate up to 18% between uncorrected and corrected images were obtained as well as a remarkable improvement of a calculated mouse femur mass has been noticed. Results were also compared to those obtained when using the simple water linearization technique which does not take into account the nonhomogeneity in the object.

  14. Efficient construction of robust artificial neural networks for accurate determination of superficial sample optical properties.

    PubMed

    Chen, Yu-Wen; Tseng, Sheng-Hao

    2015-03-01

    In general, diffuse reflectance spectroscopy (DRS) systems work with photon diffusion models to determine the absorption coefficient μa and reduced scattering coefficient μs' of turbid samples. However, in some DRS measurement scenarios, such as using short source-detector separations to investigate superficial tissues with comparable μa and μs', photon diffusion models might be invalid or might not have analytical solutions. In this study, a systematic workflow of constructing a rapid, accurate photon transport model that is valid at short source-detector separations (SDSs) and at a wide range of sample albedo is revealed. To create such a model, we first employed a GPU (Graphic Processing Unit) based Monte Carlo model to calculate the reflectance at various sample optical property combinations and established a database at high speed. The database was then utilized to train an artificial neural network (ANN) for determining the sample absorption and reduced scattering coefficients from the reflectance measured at several SDSs without applying spectral constraints. The robustness of the produced ANN model was rigorously validated. We evaluated the performance of a successfully trained ANN using tissue simulating phantoms. We also determined the 500-1000 nm absorption and reduced scattering spectra of in-vivo skin using our ANN model and found that the values agree well with those reported in several independent studies.

  15. Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2005-07-01

    We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics.

  16. Accurate Mass Determination of the Ancient White Dwarf ER 8 Through Astrometric Microlensing

    NASA Astrophysics Data System (ADS)

    Sahu, Kailash

    2004-07-01

    We propose to determine the mass of the very cool white dwarf ER 8 through astrometric microlensing. We have predicted that ER 8 will pass very close to a 15th-mag background star in January 2006, with an impact parameter of less than 0.05 arcsec. As it passes in front, it will cause a deflection of the background star's image by >8 milliarcsec, an amount easily detectable with HST/FGS. The gravitational deflection angle depends only on the distances and relative positions of the stars, and on the mass of the white dwarf. Since the distances and positions can be determined precisely before the event, the astrometric measurement offers a unique and direct method to measure the mass of the white dwarf to high accuracy {<5%}. Unlike all other stellar mass determinations, this technique works for single stars {but only if they are nearby and of sufficient mass}. The mass of ER 8 is of special interest because it is a member of the Galactic halo, and appears to be the oldest known field white dwarf. This object can thus set a lower limit on the age of the Galactic halo, but since white-dwarf cooling rates depend on their masses, the mass is a necessary ingredient in the age determination. As a byproduct, we will obtain an accurate parallax for ER 8, and thus its luminosity and {from its effective temperature} its radius. Such quantities are at present rather poorly known for the coolest white dwarfs, and will provide strong constraints on white-dwarf physics.

  17. Infrared lidar overlap function: an experimental determination.

    PubMed

    Guerrero-Rascado, Juan Luis; Costa, Maria João; Bortoli, Daniele; Silva, Ana Maria; Lyamani, Hassan; Alados-Arboledas, Lucas

    2010-09-13

    The most recent works demonstrate that the lidar overlap function, which describes the overlap between the laser beam and the receiver field of view, can be determined experimentally for the 355 and 532 nm channels using Raman signals. Nevertheless, the Raman channels cannot be used to determine the lidar overlap for the infrared channel (1064 nm) because of their low intensity. In addition, many Raman lidar systems only provide inelastic signals with reasonable signal-to-noise ratio at nighttime. In view of this fact, this work presents a modification of that method, based on the comparison of attenuated backscatter profiles derived from lidar and ceilometer, to retrieve the overlap function for the lidar infrared channel. Similarly to the Raman overlap method, the approach presented here allows to derive the overlap correction without an explicit knowledge of all system parameters. The application of the proposed methodology will improve the potential of Raman lidars to investigate the aerosol microphysical properties in the planetary boundary layer, extending the information of 1064 nm backscatter profiles to the ground and allowing the retrieval of microphysical properties practically close to the surface.

  18. An Accurate de novo Algorithm for Glycan Topology Determination from Mass Spectra.

    PubMed

    Dong, Liang; Shi, Bing; Tian, Guangdong; Li, YanBo; Wang, Bing; Zhou, MengChu

    2015-01-01

    Determining the glycan topology automatically from mass spectra represents a great challenge. Existing methods fall into approximate and exact ones. The former including greedy and heuristic ones can reduce the computational complexity, but suffer from information lost in the procedure of glycan interpretation. The latter including dynamic programming and exhaustive enumeration are much slower than the former. In the past years, nearly all emerging methods adopted a tree structure to represent a glycan. They share such problems as repetitive peak counting in reconstructing a candidate structure. Besides, tree-based glycan representation methods often have to give different computational formulas for binary and ternary glycans. We propose a new directed acyclic graph structure for glycan representation. Based on it, this work develops a de novo algorithm to accurately reconstruct the tree structure iteratively from mass spectra with logical constraints and some known biosynthesis rules, by a single computational formula. The experiments on multiple complex glycans extracted from human serum show that the proposed algorithm can achieve higher accuracy to determine a glycan topology than prior methods without increasing computational burden.

  19. Accurate determination of the complex refractive index of solid tissue-equivalent phantom

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Ye, Qing; Deng, Zhichao; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

    2012-06-01

    Tissue-equivalent phantom is becoming widespread as a substitute in the biological field to verify optical theories, test measuring systems and study the tissue performances for varying boundary conditions, sample size and shape at a quantitative level. Compared with phantoms made with Intralipid solution, ink and other liquid substances, phantom in solid state is stable over time, reproducible, easy to handle and has been testified to be a suitable optical simulator in the visible and near-infrared region. We present accurate determination of the complex refractive index (RI) of a solid tissueequivalent phantom using extended derivative total reflection method (EDTRM). Scattering phantoms in solid state were measured for p-polarized and s-polarized incident light respectively. The reflectance curves of the sample as a function of incident angle were recorded. The real part of RI is directly determined by derivative of the reflectance curve, and the imaginary part is obtained from nonlinear fitting based on the Fresnel equation and Nelder-Mead simplex method. The EDTRM method is applicable for RI measurement of high scattering media such as biotissue, solid tissue-equivalent phantom and bulk material. The obtained RI information can be used in the study of tissue optics and biomedical field.

  20. Accurate determination of residual acrylic acid in superabsorbent polymer of hygiene products by headspace gas chromatography.

    PubMed

    Zhang, Shu-Xin; Chai, Xin-Sheng; Jiang, Ran

    2017-02-17

    This work reports on a method for the determination of residual acrylic acid (AA) in the superabsorbent polymers for hygiene products by headspace analysis. It was based on water extraction for the polymer sample at a room temperature for 50min. Then, the AA in the extractant reacted with bicarbonate solution in a closed headspace sample vial, from which the carbon dioxide generated from the reaction (within 20min at 70°C) was detected by gas chromatography (GC). It was found that there is adsorption partition equilibrium of AA between solid-liquid phases. Therefore, an equation for calculating the total AA content in the original polymers sample was derived based on the above phase equilibrium. The results show that the HS-GC method has good precision (RSD<2.51%) and good accuracy (recoveries from 93 to 105%); the limit of quantification (LOQ) was 373mg/kg. The present method is rapid, accurate, and suitable for determining total residual acrylic acid in a wide variety of applications from processing of superabsorbent polymer to commercial products quality control.

  1. Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

    NASA Technical Reports Server (NTRS)

    Dominquez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

    2013-01-01

    Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

  2. Material response mechanisms are needed to obtain highly accurate experimental shock wave data

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry W.

    2017-01-01

    The field of shock wave compression of matter has provided a simple set of equations relating thermodynamic and kinematic parameters that describe the conservation of mass, momentum and energy across a steady plane shock wave with one-dimensional flow. Well-known condensed matter shock wave experimental results will be reviewed to see whether the assumptions required for deriving these simple R-H equations are satisfied. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady plane shock front. However, this statement is misleading from a practical experimental viewpoint since obtaining small systematic errors in shock wave measured parameters requires the material compression and release mechanisms to be known. A review will be presented on errors in shock wave data from common experimental techniques for elastic-plastic solids. Issues related to time scales of experiments, steady waves with long rise times and detonations will also be discussed

  3. Accurate Determination of Comet and Asteroid Orbits Leading to Collision With Earth

    NASA Technical Reports Server (NTRS)

    Roithmayr, Carlos M.; Kay-Bunnell, Linda; Mazanek, Daniel D.; Kumar, Renjith R.; Seywald, Hans; Hausman, Matthew A.

    2005-01-01

    Movements of the celestial bodies in our solar system inspired Isaac Newton to work out his profound laws of gravitation and motion; with one or two notable exceptions, all of those objects move as Newton said they would. But normally harmonious orbital motion is accompanied by the risk of collision, which can be cataclysmic. The Earth s moon is thought to have been produced by such an event, and we recently witnessed magnificent bombardments of Jupiter by several pieces of what was once Comet Shoemaker-Levy 9. Other comets or asteroids may have met the Earth with such violence that dinosaurs and other forms of life became extinct; it is this possibility that causes us to ask how the human species might avoid a similar catastrophe, and the answer requires a thorough understanding of orbital motion. The two red square flags with black square centers displayed are internationally recognized as a warning of an impending hurricane. Mariners and coastal residents who know the meaning of this symbol and the signs evident in the sky and ocean can act in advance to try to protect lives and property; someone who is unfamiliar with the warning signs or chooses to ignore them is in much greater jeopardy. Although collisions between Earth and large comets or asteroids occur much less frequently than landfall of a hurricane, it is imperative that we learn to identify the harbingers of such collisions by careful examination of an object s path. An accurate determination of the orbit of a comet or asteroid is necessary in order to know if, when, and where on the Earth s surface a collision will occur. Generally speaking, the longer the warning time, the better the chance of being able to plan and execute action to prevent a collision. The more accurate the determination of an orbit, the less likely such action will be wasted effort or, what is worse, an effort that increases rather than decreases the probability of a collision. Conditions necessary for a collision to occur are

  4. Accurate and precise determination of critical properties from Gibbs ensemble Monte Carlo simulations

    SciTech Connect

    Dinpajooh, Mohammadhasan; Bai, Peng; Allan, Douglas A.; Siepmann, J. Ilja

    2015-09-21

    Since the seminal paper by Panagiotopoulos [Mol. Phys. 61, 813 (1997)], the Gibbs ensemble Monte Carlo (GEMC) method has been the most popular particle-based simulation approach for the computation of vapor–liquid phase equilibria. However, the validity of GEMC simulations in the near-critical region has been questioned because rigorous finite-size scaling approaches cannot be applied to simulations with fluctuating volume. Valleau [Mol. Simul. 29, 627 (2003)] has argued that GEMC simulations would lead to a spurious overestimation of the critical temperature. More recently, Patel et al. [J. Chem. Phys. 134, 024101 (2011)] opined that the use of analytical tail corrections would be problematic in the near-critical region. To address these issues, we perform extensive GEMC simulations for Lennard-Jones particles in the near-critical region varying the system size, the overall system density, and the cutoff distance. For a system with N = 5500 particles, potential truncation at 8σ and analytical tail corrections, an extrapolation of GEMC simulation data at temperatures in the range from 1.27 to 1.305 yields T{sub c} = 1.3128 ± 0.0016, ρ{sub c} = 0.316 ± 0.004, and p{sub c} = 0.1274 ± 0.0013 in excellent agreement with the thermodynamic limit determined by Potoff and Panagiotopoulos [J. Chem. Phys. 109, 10914 (1998)] using grand canonical Monte Carlo simulations and finite-size scaling. Critical properties estimated using GEMC simulations with different overall system densities (0.296 ≤ ρ{sub t} ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using r{sub cut} = 3.5σ yield T{sub c} and p{sub c} that are higher by 0.2% and 1.4% than simulations with r{sub cut} = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that r{sub cut} = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard

  5. How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

    SciTech Connect

    Jones, A. Kyle; Ensor, Joe E.; Pasciak, Alexander S.

    2014-07-15

    Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ±50% using indirect dose metrics for embolization procedures. Methods: PSD were measured directly using radiochromic film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined. Results: When using the standard calculation method, calculated PSD were within ±35% for all 41 procedures studied. Calculated PSD were within ±50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ±50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (±35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from cone

  6. Accurate determination of succinimide degradation products using high fidelity trypsin digestion peptide map analysis.

    PubMed

    Yu, X Christopher; Joe, Koman; Zhang, Yu; Adriano, Andrea; Wang, Yaning; Gazzano-Santoro, Helene; Keck, Rodney G; Deperalta, Galahad; Ling, Victor

    2011-08-01

    We report an efficient, high fidelity trypsin digestion method for peptide map analysis. This method minimizes artifacts caused by the sample preparation process, and we show its utility for the accurate determination of succinimide formation in a degraded monoclonal antibody product. A basic charge variant was detected by imaged capillary isoelectric focusing and was shown with reduced antigen binding and biological activity. Samples were reduced under denaturing conditions at pH 5.0, and digestion of the reduced protein with porcine trypsin was performed at pH 7.0 for 1 h. Following reversed phase high-performance liquid chromatography and online mass spectrometric analysis, succinimide formation was identified at Asp30 in the light chain. This result contrasts with the observation of only iso-Asp and Asp residues under conventional sample preparation conditions, which are therefore concluded to be artificially generated. The Asp30 residue is seen in the cocrystal structure model to participate in favorable charge interaction with an antigen molecule. Formation of succinimide and the resulting loss of negative charge are therefore hypothesized to be the degradation mechanism. After treatment of the degraded antibody sample to mildly alkaline pH conditions, we observed only Asp residue as the succinimide hydrolysis product and concurrent recovery of biological activity.

  7. A versatile assay for the accurate, time-resolved determination of cellular viability.

    PubMed

    Amano, Toyoki; Hirasawa, Ken ichi; O'Donohue, Michael J; Pernolle, Jean Claude; Shioi, Yuzo

    2003-03-01

    A convenient and versatile method for the accurate, time-resolved determination of cellular viability has been developed. The conventional viability indicator fluorescein diacetate (FDA), which is converted to the fluorescent compound fluorescein in living cells, was employed as a viability probe. Fluorescence emission from cells was measured using a spectrofluorimeter equipped with a magnetic stirrer. Using this assay cell suspensions exhibiting densities in the range 0.5 x 10(5) to 2.0 x 10(5) cells displayed a linear response when FDA concentrations less than 12 micro M were employed. To calibrate the method, viability standards were elaborated using different proportions of living and dead cells, and a correlation coefficient for the viability of tobacco BY-2 suspensions was calculated as 0.998. This viability assay was also found to be applicable to Chlamydomonas reinhardtii and Arabidopsis thaliana cultured cells. Using this cell viability assay, kinetic analyses of cell death could be performed. Using the proteinaceous elicitor from Phytophthora cryptogea, cryptogein, to induce cell death in tobacco cell suspensions, values for the maximum velocity of death induction rate (V(max)) and the LD50 (half-maximal velocity or k(1/2)) were calculated as 17.2 (% death/h) and 65 nM, respectively.

  8. A highly accurate method for the determination of mass and center of mass of a spacecraft

    NASA Technical Reports Server (NTRS)

    Chow, E. Y.; Trubert, M. R.; Egwuatu, A.

    1978-01-01

    An extremely accurate method for the measurement of mass and the lateral center of mass of a spacecraft has been developed. The method was needed for the Voyager spacecraft mission requirement which limited the uncertainty in the knowledge of lateral center of mass of the spacecraft system weighing 750 kg to be less than 1.0 mm (0.04 in.). The method consists of using three load cells symmetrically located at 120 deg apart on a turntable with respect to the vertical axis of the spacecraft and making six measurements for each load cell. These six measurements are taken by cyclic rotations of the load cell turntable and of the spacecraft, about the vertical axis of the measurement fixture. This method eliminates all alignment, leveling, and load cell calibration errors for the lateral center of mass determination, and permits a statistical best fit of the measurement data. An associated data reduction computer program called MASCM has been written to implement this method and has been used for the Voyager spacecraft.

  9. A miniature shoe-mounted orientation determination system for accurate indoor heading and trajectory tracking.

    PubMed

    Zhang, Shengzhi; Yu, Shuai; Liu, Chaojun; Liu, Sheng

    2016-06-01

    Tracking the position of pedestrian is urgently demanded when the most commonly used GPS (Global Position System) is unavailable. Benefited from the small size, low-power consumption, and relatively high reliability, micro-electro-mechanical system sensors are well suited for GPS-denied indoor pedestrian heading estimation. In this paper, a real-time miniature orientation determination system (MODS) was developed for indoor heading and trajectory tracking based on a novel dual-linear Kalman filter. The proposed filter precludes the impact of geomagnetic distortions on pitch and roll that the heading is subjected to. A robust calibration approach was designed to improve the accuracy of sensors measurements based on a unified sensor model. Online tests were performed on the MODS with an improved turntable. The results demonstrate that the average RMSE (root-mean-square error) of heading estimation is less than 1°. Indoor heading experiments were carried out with the MODS mounted on the shoe of pedestrian. Besides, we integrated the existing MODS into an indoor pedestrian dead reckoning application as an example of its utility in realistic actions. A human attitude-based walking model was developed to calculate the walking distance. Test results indicate that mean percentage error of indoor trajectory tracking achieves 2% of the total walking distance. This paper provides a feasible alternative for accurate indoor heading and trajectory tracking.

  10. Rapid, accurate, and direct determination of total lycopene content in tomato paste

    NASA Astrophysics Data System (ADS)

    Bicanic, D.; Anese, M.; Luterotti, S.; Dadarlat, D.; Gibkes, J.; Lubbers, M.

    2003-01-01

    Lycopene that imparts red color to the tomato fruit is the most potent antioxidant among carotenes, an important nutrient and also used as a color ingredient in many food formulations. Since cooked and processed foods derived from tomatoes were shown to provide optimal lycopene boost, products such as paste, puree, juice, etc. are nowadays gaining popularity as dietary sources. The analysis of lycopene in tomato paste (partially dehydrated product prepared by vacuum concentrating tomato juice) is carried out using either high pressure liquid chromatography (HPLC), spectrophotometry, or by evaluating the color. The instability of lycopene during processes of extraction, etc., handling, and disposal of organic solvents makes the preparation of a sample for the analysis a delicate task. Despite a recognized need for accurate and rapid assessment of lycopene in tomato products no such method is available at present. The study described here focuses on a direct determination of a total lycopene content in different tomato pastes by means of the laser optothermal window (LOW) method at 502 nm. The concentration of lycopene in tomato paste ranged between 25 and 150 mg per 100 g product; the results are in excellent agreement with those obtained by spectrophotometry. The time needed to complete LOW analysis is very short, so that decomposition of pigment and the formation of artifacts are minimized. Preliminary results indicate a good degree of reproducibility making the LOW method suitable for routine assays of lycopene content in tomato paste.

  11. Final Progress Report: Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes Feasibility Study

    SciTech Connect

    Rawool-Sullivan, Mohini; Bounds, John Alan; Brumby, Steven P.; Prasad, Lakshman; Sullivan, John P.

    2012-04-30

    This is the final report of the project titled, 'Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes,' PMIS project number LA10-HUMANID-PD03. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). It summarizes work performed over the FY10 time period. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). Human analysts begin analyzing a spectrum based on features in the spectrum - lines and shapes that are present in a given spectrum. The proposed work was to carry out a feasibility study that will pick out all gamma ray peaks and other features such as Compton edges, bremsstrahlung, presence/absence of shielding and presence of neutrons and escape peaks. Ultimately success of this feasibility study will allow us to collectively explain identified features and form a realistic scenario that produced a given spectrum in the future. We wanted to develop and demonstrate machine learning algorithms that will qualitatively enhance the automated identification capabilities of portable radiological sensors that are currently being used in the field.

  12. A miniature shoe-mounted orientation determination system for accurate indoor heading and trajectory tracking

    NASA Astrophysics Data System (ADS)

    Zhang, Shengzhi; Yu, Shuai; Liu, Chaojun; Liu, Sheng

    2016-06-01

    Tracking the position of pedestrian is urgently demanded when the most commonly used GPS (Global Position System) is unavailable. Benefited from the small size, low-power consumption, and relatively high reliability, micro-electro-mechanical system sensors are well suited for GPS-denied indoor pedestrian heading estimation. In this paper, a real-time miniature orientation determination system (MODS) was developed for indoor heading and trajectory tracking based on a novel dual-linear Kalman filter. The proposed filter precludes the impact of geomagnetic distortions on pitch and roll that the heading is subjected to. A robust calibration approach was designed to improve the accuracy of sensors measurements based on a unified sensor model. Online tests were performed on the MODS with an improved turntable. The results demonstrate that the average RMSE (root-mean-square error) of heading estimation is less than 1°. Indoor heading experiments were carried out with the MODS mounted on the shoe of pedestrian. Besides, we integrated the existing MODS into an indoor pedestrian dead reckoning application as an example of its utility in realistic actions. A human attitude-based walking model was developed to calculate the walking distance. Test results indicate that mean percentage error of indoor trajectory tracking achieves 2% of the total walking distance. This paper provides a feasible alternative for accurate indoor heading and trajectory tracking.

  13. Accurate Hf isotope determinations of complex zircons using the "laser ablation split stream" method

    NASA Astrophysics Data System (ADS)

    Fisher, Christopher M.; Vervoort, Jeffery D.; DuFrane, S. Andrew

    2014-01-01

    The "laser ablation split stream" (LASS) technique is a powerful tool for mineral-scale isotope analyses and in particular, for concurrent determination of age and Hf isotope composition of zircon. Because LASS utilizes two independent mass spectrometers, a large range of masses can be measured during a single ablation, and thus, the same sample volume can be analyzed for multiple geochemical systems. This paper describes a simple analytical setup using a laser ablation system coupled to a single-collector (for U-Pb age determination) and a multicollector (for Hf isotope analyses) inductively coupled plasma mass spectrometer (MC-ICPMS). The ability of the LASS for concurrent Hf + age technique to extract meaningful Hf isotope compositions in isotopically zoned zircon is demonstrated using zircons from two Proterozoic gneisses from northern Idaho, USA. These samples illustrate the potential problems associated with inadvertently sampling multiple age and Hf components in zircons, as well as the potential of LASS to recover meaningful Hf isotope compositions. We suggest that such inadvertent sampling of differing age and Hf components can be a significant cause of excess scatter in Hf isotope analyses and demonstrate that the LASS approach offers a robust solution to these issues. The veracity of the approach is demonstrated by accurate analyses of 10 reference zircons with well-characterized age and Hf isotopic composition, using laser spot diameters of 30 and 40 µm. In order to expand the database of high-precision Lu-Hf isotope analyses of reference zircons, we present 27 new isotope dilution-MC-ICPMS Lu-Hf isotope measurements of five U-Pb zircon standards: FC1, Temora, R33, QGNG, and 91500.

  14. Evolutionary determination of experimental parameters for ptychographical imaging

    SciTech Connect

    Shenfield, Alex; Rodenburg, John M.

    2011-06-15

    The Ptychographical Iterative Engine (PIE) algorithm is a recently developed novel method of Coherent Diffractive Imaging (CDI) that uses multiple overlapping diffraction patterns to reconstruct an image. This method has successfully produced high quality reconstructions at both optical and X-ray wavelengths but the need for accurate knowledge of the probe positions is currently a limiting factor in the production of high resolution reconstructions at electron wavelengths. This paper examines the shape of the search landscape for producing optimal image reconstructions in the specific case of electron microscopy and then shows how evolutionary search methods can be used to reliably determine experimental parameters in the electron microscopy case (such as the spherical aberration in the probe and the probe positions).

  15. Accurate determination of the first ionization potential of actinides by laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Trautmann, N.

    1994-10-01

    A new method is described for the precise determination of the first ionization potential of elements which are available only in small amounts such as the heavier actinides. It is based on resonance ionization mass spectroscopy (RIMS) in the presence of an external electric field. Extrapolation of the ionization thresholds obtained with different electric field strengths to field strength zero leads directly to the first ionization potential. With samples of 10(exp 12) atoms of Np-237 and Am-243 experimental values for the first ionization potential of neptunium of IP(sub Np) = 6.2655(2) eV and of americium of IP(sub Am) = 5.9738(2) eV were obtained. This technique was also applied to thorium yielding a value of IP(sub Th) = 6.3067(2) eV. In addition the precision of the method was confirmed by the convergences of Rydberg series of americium measured by means of RIMS.

  16. Accurate determination of screw position in treating fifth metatarsal base fractures to shorten radiation exposure time

    PubMed Central

    Wang, Xu; Zhang, Chao; Wang, Chen; Huang, Jia Zhang; Ma, Xin

    2016-01-01

    INTRODUCTION Anatomical markers can help to guide lag screw placement during surgery for internal fixation of fifth metatarsal base fractures. This study aimed to identify the optimal anatomical markers and thus reduce radiation exposure. METHODS A total of 50 patients in Huashan Hospital, Shanghai, China, who underwent oblique foot radiography in the lateral position were randomly selected. The angles between the fifth metatarsal axis and cuboid articular surface were measured to determine the optimal lag screw placement relative to anatomical markers. RESULTS The line connecting the styloid process of the fifth metatarsal base with the second metatarsophalangeal (MTP) joint intersected with the fifth metatarsal base fracture line at an angle of 86.85° ± 5.44°. The line connecting the fifth metatarsal base styloid with the third and fourth MTP joints intersected with the fracture line at angles of 93.28° ± 5.24° and 100.95° ± 5.00°, respectively. The proximal articular surface of the fifth metatarsal base intersected with the line connecting the styloid process of the fifth metatarsal base with the second, third and fourth MTP joints at angles of 24.02° ± 4.77°, 30.79° ± 4.53° and 38.08° ± 4.54°, respectively. CONCLUSION The fifth metatarsal base styloid and third MTP joint can be used as anatomical markers for lag screw placement in fractures involving the fifth tarsometatarsal joint. The connection line, which is normally perpendicular to the fracture line, provides sufficient mechanical stability to facilitate accurate screw placement. The use of these anatomical markers could help to reduce unnecessary radiation exposure for patients and medical staff. PMID:26767892

  17. Linear signal noise summer accurately determines and controls S/N ratio

    NASA Technical Reports Server (NTRS)

    Sundry, J. L.

    1966-01-01

    Linear signal noise summer precisely controls the relative power levels of signal and noise, and mixes them linearly in accurately known ratios. The S/N ratio accuracy and stability are greatly improved by this technique and are attained simultaneously.

  18. Accurate modeling of antennas for radiating short pulses, FDTD analysis and experimental measurements

    NASA Astrophysics Data System (ADS)

    Maloney, James G.; Smith, Glenn S.

    1993-01-01

    Antennas used to radiate short pulses often require different design rules that those that are used to radiate essentially time-harmonic signals. The finite-difference time-domain (FDTD) method is a very flexible numerical approach that can be used to treat a variety of electromagnetic problems in the time domain. It is well suited to the analysis and design of antennas for radiating short pulses; however, several advances had to be made before the method could be applied to this problem. In this paper, we will illustrate the use of the FDTD method with two antennas designed for the radiation of short pulses. The first is a simple, two-dimensional geometry, and open-ended parallel-plate waveguide, while the second is a three-dimensional, rotationally symmetric geometry, a conical monopole fed through an image by a coaxial transmission line. Both antennas are 'optimized' according to given criteria by adjusting geometrical parameters and including resistive loading that varies continuously with position along the antenna. The predicted performance for the conical monopole antenna is compared with experimental measurements; this verifies the optimization and demonstrates the practicality of the design.

  19. Convenient, Rapid and Accurate Measurement of SVOC Emission Characteristics in Experimental Chambers

    PubMed Central

    Liu, Cong; Liu, Zhe; Little, John C.; Zhang, Yinping

    2013-01-01

    Chamber tests are usually used to determine the source characteristics of semi-volatile organic compounds (SVOCs) which are critical to quantify indoor exposure to SVOCs. In contrast to volatile organic compounds (VOCs), the sorption effect of SVOCs to chamber surfaces usually needs to be considered due to the much higher surface/air partition coefficients, resulting in a long time to reach steady state, frequently on the order of months, and complicating the mathematical analysis of the resulting data. A chamber test is also complicated if the material-phase concentration is not constant. This study shows how to design a chamber to overcome these limitations. A dimensionless mass transfer analysis is used to specify conditions for (1) neglecting the SVOC sorption effect to chamber surfaces, (2) neglecting the convective mass transfer resistance at sorption surfaces if the sorption effect cannot be neglected, and (3) regarding the material-phase concentration in the source as constant. Several practical and quantifiable ways to improve chamber design are proposed. The approach is illustrated by analyzing available data from three different chambers in terms of the accuracy with which the model parameters can be determined and the time needed to conduct the chamber test. The results should greatly facilitate the design of chambers to characterize SVOC emissions and the resulting exposure. PMID:24015246

  20. Modeling of Non-Gravitational Forces for Precise and Accurate Orbit Determination

    NASA Astrophysics Data System (ADS)

    Hackel, Stefan; Gisinger, Christoph; Steigenberger, Peter; Balss, Ulrich; Montenbruck, Oliver; Eineder, Michael

    2014-05-01

    Remote sensing satellites support a broad range of scientific and commercial applications. The two radar imaging satellites TerraSAR-X and TanDEM-X provide spaceborne Synthetic Aperture Radar (SAR) and interferometric SAR data with a very high accuracy. The precise reconstruction of the satellite's trajectory is based on the Global Positioning System (GPS) measurements from a geodetic-grade dual-frequency Integrated Geodetic and Occultation Receiver (IGOR) onboard the spacecraft. The increasing demand for precise radar products relies on validation methods, which require precise and accurate orbit products. An analysis of the orbit quality by means of internal and external validation methods on long and short timescales shows systematics, which reflect deficits in the employed force models. Following the proper analysis of this deficits, possible solution strategies are highlighted in the presentation. The employed Reduced Dynamic Orbit Determination (RDOD) approach utilizes models for gravitational and non-gravitational forces. A detailed satellite macro model is introduced to describe the geometry and the optical surface properties of the satellite. Two major non-gravitational forces are the direct and the indirect Solar Radiation Pressure (SRP). The satellite TerraSAR-X flies on a dusk-dawn orbit with an altitude of approximately 510 km above ground. Due to this constellation, the Sun almost constantly illuminates the satellite, which causes strong across-track accelerations on the plane rectangular to the solar rays. The indirect effect of the solar radiation is called Earth Radiation Pressure (ERP). This force depends on the sunlight, which is reflected by the illuminated Earth surface (visible spectra) and the emission of the Earth body in the infrared spectra. Both components of ERP require Earth models to describe the optical properties of the Earth surface. Therefore, the influence of different Earth models on the orbit quality is assessed. The scope of

  1. A new sensor system for accurate and precise determination of sediment dynamics and position.

    NASA Astrophysics Data System (ADS)

    Maniatis, Georgios; Hoey, Trevor; Sventek, Joseph; Hodge, Rebecca

    2014-05-01

    Sediment transport processes control many significant geomorphological changes. Consequently, sediment transport dynamics are studied across a wide range of scales leading to application of a variety of conceptually different mathematical descriptions (models) and data acquisition techniques (sensing). For river sediment transport processes both Eulerian and Lagrangian formulations are used. Data are gathered using a very wide range of sensing techniques that are not always compatible with the conceptual formulation applied. We are concerned with small to medium sediment grain-scale motion in gravel-bed rivers, and other coarse-grained environments, and: a) are developing a customised environmental sensor capable of providing coherent data that reliably record the motion; and, b) provide a mathematical framework in which these data can be analysed and interpreted, this being compatible with current stochastic approaches to sediment transport theory. Here we present results from three different aspects of the above developmental process. Firstly, we present a requirement analysis for the sensor based on the state of the art of the existing technologies. We focus on the factors that enhance data coherence and representativeness, extending the common practice for optimization which is based exclusively on electronics/computing related criteria. This analysis leads to formalization of a method that permits accurate control on the physical properties of the sensor using contemporary rapid prototyping techniques [Maniatis et al. 2013]. Secondly the first results are presented from a series of entrainment experiments in a 5 x 0.8 m flume in which a prototype sensor was deployed to monitor entrainment dynamics under increasing flow conditions (0.037 m3.s-1). The sensor was enclosed in an idealized spherical case (111 mm diameter) and placed on a constructed bed of hemispheres of the same diameter. We measured 3-axial inertial acceleration (as a measure of flow stress

  2. Accurate determination of specific heat at high temperatures using the flash diffusivity method

    NASA Technical Reports Server (NTRS)

    Vandersande, J. W.; Zoltan, A.; Wood, C.

    1989-01-01

    The flash diffusivity method of Parker et al. (1961) was used to measure accurately the specific heat of test samples simultaneously with thermal diffusivity, thus obtaining the thermal conductivity of these materials directly. The accuracy of data obtained on two types of materials (n-type silicon-germanium alloys and niobium), was + or - 3 percent. It is shown that the method is applicable up to at least 1300 K.

  3. An Experimental Determination of Thermodynamic Values

    ERIC Educational Resources Information Center

    Antony, Erling; Muccianti, Christine; Vogel, Tracy

    2012-01-01

    Measurements have been added to an old demonstration of chemical equilibria allowing the determination of thermodynamic constants. The experiment allows the students an opportunity to merge qualitative observations associated with Le Chatelier's principle and thermodynamic calculations using graphical techniques. (Contains 4 figures.)

  4. Experimental determination of dielectric barrier discharge capacitance

    NASA Astrophysics Data System (ADS)

    Pipa, A. V.; Hoder, T.; Koskulics, J.; Schmidt, M.; Brandenburg, R.

    2012-07-01

    The determination of electrical parameters (such as instantaneous power, transferred charge, and gas gap voltage) in dielectric barrier discharge (DBD) reactors relies on estimates of key capacitance values. In the classic large-scale sinusoidal-voltage driven DBD, also known as silent or ozonizer discharge, capacitance values can be determined from charge-voltage (Q-V) plot, also called Lissajous figure. For miniature laboratory reactors driven by fast pulsed voltage waveforms with sub-microsecond rise time, the capacitance of the dielectric barriers cannot be evaluated from a single Q-V plot because of the limited applicability of the classical theory. Theoretical determination can be problematic due to electrode edge effects, especially in the case of asymmetrical electrodes. The lack of reliable capacitance estimates leads to a "capacitance bottleneck" that obstructs the determination of other DBD electrical parameters in fast-pulsed reactors. It is suggested to obtain capacitance of dielectric barriers from a plot of the maximal charge versus maximal voltage amplitude (Qmax - Vmax plot) in a manner analogous to the classical approach. The method is examined using measurements of current and voltage waveforms of a coaxial DBD reactor in argon at 100 mbar driven by square voltage pulses with a rise time of 20 ns and with different voltage amplitudes up to 10 kV. Additionally, the applicability of the method has been shown for the data reported in literature measured at 1 bar of nitrogen-oxygen gas mixtures and xenon.

  5. A Simple yet Accurate Method for Students to Determine Asteroid Rotation Periods from Fragmented Light Curve Data

    ERIC Educational Resources Information Center

    Beare, R. A.

    2008-01-01

    Professional astronomers use specialized software not normally available to students to determine the rotation periods of asteroids from fragmented light curve data. This paper describes a simple yet accurate method based on Microsoft Excel[R] that enables students to find periods in asteroid light curve and other discontinuous time series data of…

  6. Accurate label-free reaction kinetics determination using initial rate heat measurements

    PubMed Central

    Ebrahimi, Kourosh Honarmand; Hagedoorn, Peter-Leon; Jacobs, Denise; Hagen, Wilfred R.

    2015-01-01

    Accurate label-free methods or assays to obtain the initial reaction rates have significant importance in fundamental studies of enzymes and in application-oriented high throughput screening of enzyme activity. Here we introduce a label-free approach for obtaining initial rates of enzyme activity from heat measurements, which we name initial rate calorimetry (IrCal). This approach is based on our new finding that the data recorded by isothermal titration calorimetry for the early stages of a reaction, which have been widely ignored, are correlated to the initial rates. Application of the IrCal approach to various enzymes led to accurate enzyme kinetics parameters as compared to spectroscopic methods and enabled enzyme kinetic studies with natural substrate, e.g. proteases with protein substrates. Because heat is a label-free property of almost all reactions, the IrCal approach holds promise in fundamental studies of various enzymes and in use of calorimetry for high throughput screening of enzyme activity. PMID:26574737

  7. Accurate determination of the free-free Gaunt factor - II. Relativistic Gaunt factors

    NASA Astrophysics Data System (ADS)

    van Hoof, P. A. M.; Ferland, G. J.; Williams, R. J. R.; Volk, K.; Chatzikos, M.; Lykins, M.; Porter, R. L.

    2015-05-01

    When modelling an ionized plasma, all spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum. Until now no data set exists that would meet these needs completely. We have therefore produced a table of relativistic Gaunt factors over a much wider range of parameter space than has ever been produced before. We present tables of the thermally averaged Gaunt factor covering the range 10log γ2 = -6 to 10 and 10log u = -16 to 13 for all atomic numbers Z = 1 through 36. The data were calculated using the relativistic Bethe-Heitler-Elwert (BHE) approximation and were subsequently merged with accurate non-relativistic results in those parts of the parameter space where the BHE approximation is not valid. These data will be incorporated in the next major release of the spectral synthesis code CLOUDY. We also produced tables of the frequency integrated Gaunt factor covering the parameter space 10log γ2 = -6 to +10 for all values of Z between 1 and 36. All the data presented in this paper are available online.

  8. DFT SOLVATION STUDIES OF CARBOHYDRATES: DETERMINATION OF ACCURATE ALPHA/BETA-ANOMERIC RATIOS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solvents play an important role in carbohydrate structure. Therefore, it is important to include solvation effects in calculations to allow a better comparison with experimental data. One way to include solvation effects is via the use of continuum solvation models such as COSMO. Another possibil...

  9. One-photon mass-analyzed threshold ionization (MATI) spectroscopy of pyridine: Determination of accurate ionization energy and cationic structure

    NASA Astrophysics Data System (ADS)

    Lee, Yu Ran; Kang, Do Won; Kim, Hong Lae; Kwon, Chan Ho

    2014-11-01

    Ionization energies and cationic structures of pyridine were intensively investigated utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The present one-photon high-resolution MATI spectrum of pyridine demonstrated a much finer and richer vibrational structure than that of the previously reported two-photon MATI spectrum. From the MATI spectrum and photoionization efficiency curve, the accurate ionization energy of the ionic ground state of pyridine was confidently determined to be 73 570 ± 6 cm-1 (9.1215 ± 0.0007 eV). The observed spectrum was almost completely assigned by utilizing Franck-Condon factors and vibrational frequencies calculated through adjustments of the geometrical parameters of cationic pyridine at the B3LYP/cc-pVTZ level. A unique feature unveiled through rigorous analysis was the prominent progression of the 10 vibrational mode, which corresponds to in-plane ring bending, and the combination of other totally symmetric fundamentals with the ring bending overtones, which contribute to the geometrical change upon ionization. Notably, the remaining peaks originate from the upper electronic state (2A2), as predicted by high-resolution photoelectron spectroscopy studies and symmetry-adapted cluster configuration interaction calculations. Based on the quantitatively good agreement between the experimental and calculated results, it was concluded that upon ionization the pyridine cation in the ground electronic state should have a planar structure of C2v symmetry through the C-N axis.

  10. One-photon mass-analyzed threshold ionization (MATI) spectroscopy of pyridine: Determination of accurate ionization energy and cationic structure

    SciTech Connect

    Lee, Yu Ran; Kang, Do Won; Kim, Hong Lae E-mail: hlkim@kangwon.ac.kr; Kwon, Chan Ho E-mail: hlkim@kangwon.ac.kr

    2014-11-07

    Ionization energies and cationic structures of pyridine were intensively investigated utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The present one-photon high-resolution MATI spectrum of pyridine demonstrated a much finer and richer vibrational structure than that of the previously reported two-photon MATI spectrum. From the MATI spectrum and photoionization efficiency curve, the accurate ionization energy of the ionic ground state of pyridine was confidently determined to be 73 570 ± 6 cm{sup −1} (9.1215 ± 0.0007 eV). The observed spectrum was almost completely assigned by utilizing Franck-Condon factors and vibrational frequencies calculated through adjustments of the geometrical parameters of cationic pyridine at the B3LYP/cc-pVTZ level. A unique feature unveiled through rigorous analysis was the prominent progression of the 10 vibrational mode, which corresponds to in-plane ring bending, and the combination of other totally symmetric fundamentals with the ring bending overtones, which contribute to the geometrical change upon ionization. Notably, the remaining peaks originate from the upper electronic state ({sup 2}A{sub 2}), as predicted by high-resolution photoelectron spectroscopy studies and symmetry-adapted cluster configuration interaction calculations. Based on the quantitatively good agreement between the experimental and calculated results, it was concluded that upon ionization the pyridine cation in the ground electronic state should have a planar structure of C{sub 2v} symmetry through the C-N axis.

  11. Experimental determination of baseball spin and lift.

    PubMed

    Alaways, L W; Hubbard, M

    2001-05-01

    The aim of this study was to develop a new method for the determination of lift on spinning baseballs. Inertial trajectories of (a) ball surface markers during the first metre of flight and (b) the centre of mass trajectory near home-plate were measured in a pitch using high-speed video. A theoretical model was developed, incorporating aerodynamic Magnus-Robins lift, drag and cross forces, which predicts the centre of mass and marker trajectories. Parameters including initial conditions and aerodynamic coefficients were estimated iteratively by minimizing the error between predicted and measured trajectories. We compare the resulting lift coefficients and spin parameter values with those of previous studies. Lift on four-seam pitches can be as much as three times that of two-seam pitches, although this disparity is reduced for spin parameters greater than 0.4.

  12. Experimental Determination of Chemical Diffusion within Secondary Organic Aerosol Particles

    SciTech Connect

    Abramson, Evan H.; Imre, D.; Beranek, Josef; Wilson, Jacqueline; Zelenyuk, Alla

    2013-02-28

    Formation, properties, transformations, and temporal evolution of secondary organic aerosols (SOA) particles strongly depend on particle phase. Recent experimental evidence from a number of groups indicates that SOA is in a semi-solid phase, the viscosity of which remained unknown. We find that when SOA is made in the presence of vapors of volatile hydrophobic molecules the SOA particles absorb and trap them. Here, we illustrate that it is possible to measure the evaporation rate of these molecules that is determined by their diffusion in SOA, which is then used to calculate a reasonably accurate value for the SOA viscosity. We use pyrene as a tracer molecule and a-pinene SOA as an illustrative case. It takes ~24 hours for half the pyrene to evaporate to yield a viscosity of 10^8 Pa s for a-pinene. This viscosity is consistent with measurements of particle bounce and evaporation rates. We show that viscosity of 10^8 Pa s implies coalescence times of minutes, consistent with the findings that SOA particles are spherical. Similar measurements on aged SOA particles doped with pyrene yield a viscosity of 10^9 Pa s, indicating that hardening occurs with time, which is consistent with observed decrease in water uptake and evaporation rate with aging.

  13. Selection of soluble protein expression constructs: the experimental determination of protein domain boundaries.

    PubMed

    Dyson, Michael R

    2010-08-01

    Proteins can contain multiple domains each of which is capable of possessing a separate independent function and three-dimensional structure. It is often useful to clone and express individual protein domains to study their biochemical properties and for structure determination. However, the annotated domain boundaries in databases such as Pfam or SMART are not always accurate. The present review summarizes various strategies for the experimental determination of protein domain boundaries.

  14. Test system accurately determines tensile properties of irradiated metals at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Levine, P. J.; Skalka, R. J.; Vandergrift, E. F.

    1967-01-01

    Modified testing system determines tensile properties of irradiated brittle-type metals at cryogenic temperatures. The system includes a lightweight cryostat, split-screw grips, a universal joint, and a special temperature control system.

  15. A framework for accurate determination of the T₂ distribution from multiple echo magnitude MRI images.

    PubMed

    Bai, Ruiliang; Koay, Cheng Guan; Hutchinson, Elizabeth; Basser, Peter J

    2014-07-01

    Measurement of the T2 distribution in tissues provides biologically relevant information about normal and abnormal microstructure and organization. Typically, the T2 distribution is obtained by fitting the magnitude MR images acquired by a multi-echo MRI pulse sequence using an inverse Laplace transform (ILT) algorithm. It is well known that the ideal magnitude MR signal follows a Rician distribution. Unfortunately, studies attempting to establish the validity and efficacy of the ILT algorithm assume that these input signals are Gaussian distributed. Violation of the normality (or Gaussian) assumption introduces unexpected artifacts, including spurious cerebrospinal fluid (CSF)-like long T2 components; bias of the true geometric mean T2 values and in the relative fractions of various components; and blurring of nearby T2 peaks in the T2 distribution. Here we apply and extend our previously proposed magnitude signal transformation framework to map noisy Rician-distributed magnitude multi-echo MRI signals into Gaussian-distributed signals with high accuracy and precision. We then perform an ILT on the transformed data to obtain an accurate T2 distribution. Additionally, we demonstrate, by simulations and experiments, that this approach corrects the aforementioned artifacts in magnitude multi-echo MR images over a large range of signal-to-noise ratios.

  16. The importance of suppressing spin diffusion effects in the accurate determination of the spatial structure of a flexible molecule by nuclear Overhauser effect spectroscopy

    NASA Astrophysics Data System (ADS)

    Khodov, I. A.; Efimov, S. V.; Klochkov, V. V.; Batista de Carvalho, L. A. E.; Kiselev, M. G.

    2016-02-01

    Two-dimensional nuclear Overhauser effect spectroscopy is applied to the elucidation of conformation distribution of small molecules in solution. An essential influence of the nonlinear multistep magnetization transfer (spin diffusion) on the NMR-based analysis of conformers distribution for small druglike molecules in solution was revealed. Therefore, the spin diffusion should be eliminated from the obtained NMR data in order to obtain accurate results. Efficiency of QUIET-NOESY spectroscopy in solving the problem of accurate determination of inter-proton distances in a small molecule was shown in a study of ibuprofen. Although it requires much experimental time, this technique was found to be helpful to solve the spin diffusion problem.

  17. Theory of bi-molecular association dynamics in 2D for accurate model and experimental parameterization of binding rates

    PubMed Central

    Yogurtcu, Osman N.; Johnson, Margaret E.

    2015-01-01

    The dynamics of association between diffusing and reacting molecular species are routinely quantified using simple rate-equation kinetics that assume both well-mixed concentrations of species and a single rate constant for parameterizing the binding rate. In two-dimensions (2D), however, even when systems are well-mixed, the assumption of a single characteristic rate constant for describing association is not generally accurate, due to the properties of diffusional searching in dimensions d ≤ 2. Establishing rigorous bounds for discriminating between 2D reactive systems that will be accurately described by rate equations with a single rate constant, and those that will not, is critical for both modeling and experimentally parameterizing binding reactions restricted to surfaces such as cellular membranes. We show here that in regimes of intrinsic reaction rate (ka) and diffusion (D) parameters ka/D > 0.05, a single rate constant cannot be fit to the dynamics of concentrations of associating species independently of the initial conditions. Instead, a more sophisticated multi-parametric description than rate-equations is necessary to robustly characterize bimolecular reactions from experiment. Our quantitative bounds derive from our new analysis of 2D rate-behavior predicted from Smoluchowski theory. Using a recently developed single particle reaction-diffusion algorithm we extend here to 2D, we are able to test and validate the predictions of Smoluchowski theory and several other theories of reversible reaction dynamics in 2D for the first time. Finally, our results also mean that simulations of reactive systems in 2D using rate equations must be undertaken with caution when reactions have ka/D > 0.05, regardless of the simulation volume. We introduce here a simple formula for an adaptive concentration dependent rate constant for these chemical kinetics simulations which improves on existing formulas to better capture non-equilibrium reaction dynamics from dilute

  18. Accurate determination of volume and evaporation rate of micron-size liquid particle

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Sasagawa, N.; Sakai, K.

    2010-09-01

    We developed a noncontact method to measure the liquid droplet size of about 10 μm diameter within accuracy of 0.1 μm. A droplet ejected by an inkjet nozzle is induced into the glass windshield and falls due to the gravity against the viscosity of the atmosphere. The droplet is illuminated by a laser passing along the center of the glass windshield and the droplet diameter is determined from the falling velocity by the video analysis with the knowledge about the density of the droplet, and the viscosity of the atmosphere. The real time measurement of the droplet size through the rapid evaporation process thus becomes possible. The evaporation rate from the pure water droplet determined by the present method was found be more than 200 times larger than that from the surface with macroscopic spatial scale.

  19. Accurate determination of frequency dependent three element equivalent circuit for symmetric step microstrip discontinuity

    NASA Astrophysics Data System (ADS)

    Webster, M. J.; Easter, B.; Hornsby, J. S.

    1990-02-01

    A three element frequency dependent equivalent circuit which characterizes a symmetric step microstrip discontinuity is determined using the method of lines. This method was applied so as to exploit to the full the processing capabilities of the available Cyber 205 computer, and to obtain results with the highest possible accuracy at frequencies in the range 4-16 GHz. Numerical values of scattering parameters are given for three geometries.

  20. Raman Spectroscopy Provides a Powerful Diagnostic Tool for Accurate Determination of Albumin Glycation

    PubMed Central

    Dingari, Narahara Chari; Horowitz, Gary L.; Kang, Jeon Woong; Dasari, Ramachandra R.; Barman, Ishan

    2012-01-01

    We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future. PMID:22393405

  1. A simple and inclusive method to determine the habit plane in transmission electron microscope based on accurate measurement of foil thickness

    SciTech Connect

    Qiu, Dong Zhang, Mingxing

    2014-08-15

    A simple and inclusive method is proposed for accurate determination of the habit plane between bicrystals in transmission electron microscope. Whilst this method can be regarded as a variant of surface trace analysis, the major innovation lies in the improved accuracy and efficiency of foil thickness measurement, which involves a simple tilt of the thin foil about a permanent tilting axis of the specimen holder, rather than cumbersome tilt about the surface trace of the habit plane. Experimental study has been done to validate this proposed method in determining the habit plane between lamellar α{sub 2} plates and γ matrix in a Ti–Al–Nb alloy. Both high accuracy (± 1°) and high precision (± 1°) have been achieved by using the new method. The source of the experimental errors as well as the applicability of this method is discussed. Some tips to minimise the experimental errors are also suggested. - Highlights: • An improved algorithm is formulated to measure the foil thickness. • Habit plane can be determined with a single tilt holder based on the new algorithm. • Better accuracy and precision within ± 1° are achievable using the proposed method. • The data for multi-facet determination can be collected simultaneously.

  2. Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

    NASA Astrophysics Data System (ADS)

    Dönsberg, Timo; Mäntynen, Henrik; Ikonen, Erkki

    2016-06-01

    The measurement uncertainty of illuminance and, consequently, luminous flux and luminous efficacy of LED lamps can be reduced with a recently introduced method based on the predictable quantum efficient detector (PQED). One of the most critical factors affecting the measurement uncertainty with the PQED method is the determination of the aperture area. This paper describes an upgrade to an optical method for direct determination of aperture area where superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by scanning the aperture in front of an intensity-stabilized laser beam. In the upgraded method, the aperture is attached to the PQED and the whole package is transversely scanned relative to the laser beam. This has the benefit of having identical geometry in the laser scanning of the aperture area and in the actual photometric measurement. Further, the aperture and detector assembly does not have to be dismantled for the aperture calibration. However, due to small acceptance angle of the PQED, differences between the diffraction effects of an overfilling plane wave and of a combination of Gaussian laser beams at the circular aperture need to be taken into account. A numerical calculation method for studying these effects is discussed in this paper. The calculation utilizes the Rayleigh-Sommerfeld diffraction integral, which is applied to the geometry of the PQED and the aperture. Calculation results for various aperture diameters and two different aperture-to-detector distances are presented.

  3. [Extracting THz absorption coefficient spectrum based on accurate determination of sample thickness].

    PubMed

    Li, Zhi; Zhang, Zhao-hui; Zhao, Xiao-yan; Su, Hai-xia; Yan, Fang

    2012-04-01

    Extracting absorption spectrum in THz band is one of the important aspects in THz applications. Sample's absorption coefficient has a complex nonlinear relationship with its thickness. However, as it is not convenient to measure the thickness directly, absorption spectrum is usually determined incorrectly. Based on the method proposed by Duvillaret which was used to precisely determine the thickness of LiNbO3, the approach to measuring the absorption coefficient spectra of glutamine and histidine in frequency range from 0.3 to 2.6 THz(1 THz = 10(12) Hz) was improved in this paper. In order to validate the correctness of this absorption spectrum, we designed a series of experiments to compare the linearity of absorption coefficient belonging to one kind amino acid in different concentrations. The results indicate that as agreed by Lambert-Beer's Law, absorption coefficient spectrum of amino acid from the improved algorithm performs better linearity with its concentration than that from the common algorithm, which can be the basis of quantitative analysis in further researches.

  4. Development and experimental verification of a finite element method for accurate analysis of a surface acoustic wave device

    NASA Astrophysics Data System (ADS)

    Mohibul Kabir, K. M.; Matthews, Glenn I.; Sabri, Ylias M.; Russo, Salvy P.; Ippolito, Samuel J.; Bhargava, Suresh K.

    2016-03-01

    Accurate analysis of surface acoustic wave (SAW) devices is highly important due to their use in ever-growing applications in electronics, telecommunication and chemical sensing. In this study, a novel approach for analyzing the SAW devices was developed based on a series of two-dimensional finite element method (FEM) simulations, which has been experimentally verified. It was found that the frequency response of the two SAW device structures, each having slightly different bandwidth and center lobe characteristics, can be successfully obtained utilizing the current density of the electrodes via FEM simulations. The two SAW structures were based on XY Lithium Niobate (LiNbO3) substrates and had two and four electrode finger pairs in both of their interdigital transducers, respectively. Later, SAW devices were fabricated in accordance with the simulated models and their measured frequency responses were found to correlate well with the obtained simulations results. The results indicated that better match between calculated and measured frequency response can be obtained when one of the input electrode finger pairs was set at zero volts and all the current density components were taken into account when calculating the frequency response of the simulated SAW device structures.

  5. Accurate determination of silver nanoparticles in animal tissues by inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Veverková, Lenka; Hradilová, Šárka; Milde, David; Panáček, Aleš; Skopalová, Jana; Kvítek, Libor; Petrželová, Kamila; Zbořil, Radek

    2014-12-01

    This study examined recoveries of silver determination in animal tissues after wet digestion by inductively coupled plasma mass spectrometry. The composition of the mineralization mixture for microwave assisted digestion was optimized and the best recoveries were obtained for mineralization with HNO3 and addition of HCl promptly after digestion. The optimization was performed on model samples of chicken meat spiked with silver nanoparticles and a solution of ionic silver. Basic calculations of theoretical distribution of Ag among various silver-containing species were implemented and the results showed that most of the silver is in the form of soluble complexes AgCl2- and AgCl32 - for the optimized composition of the mineralization mixture. Three animal tissue certified reference materials were then analyzed to verify the trueness and precision of the results.

  6. 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

  7. Note: Accurate determination of thickness of multiple layers of thin film deposited on a piezoelectric quartz crystal.

    PubMed

    Wajid, Abdul

    2013-10-01

    Modern day piezoelectric quartz crystal microbalances for thin film deposition control are based on Z-match equation, which is mathematically valid for deposition of a single material on a given quartz crystal. When multiple layers are deposited, thickness and deposition rate errors accumulate due to mismatch of acoustic impedance of different materials. Here we present a novel method, based on the acoustic transfer matrix formalism, for accurate determination of thickness of an arbitrary number of layers of dissimilar materials deposited on a quartz crystal. Laboratory data show excellent accuracy of the method compared to conventional Z-match equation.

  8. Note: Accurate determination of thickness of multiple layers of thin film deposited on a piezoelectric quartz crystal

    NASA Astrophysics Data System (ADS)

    Wajid, Abdul

    2013-10-01

    Modern day piezoelectric quartz crystal microbalances for thin film deposition control are based on Z-match equation, which is mathematically valid for deposition of a single material on a given quartz crystal. When multiple layers are deposited, thickness and deposition rate errors accumulate due to mismatch of acoustic impedance of different materials. Here we present a novel method, based on the acoustic transfer matrix formalism, for accurate determination of thickness of an arbitrary number of layers of dissimilar materials deposited on a quartz crystal. Laboratory data show excellent accuracy of the method compared to conventional Z-match equation.

  9. Fast and Accurate Technique for Determination of Moisture Content in Oil Palm Fruits using Open-Ended Coaxial Sensor

    NASA Astrophysics Data System (ADS)

    Abbas, Zulkifly; Yeow, You Kok; Shaari, Abdul Halim; Zakaria, Azmi; Hassan, Jumiah; Khalid, Kaida; Saion, Elias

    2005-07-01

    A simple, fast and accurate technique employing an open-ended coaxial sensor for the determination of the moisture content in oil palm fruit is presented. For this technique, a calibration equation has been developed based on the relationship between the measured moisture content obtained by the oven drying method and the phase of the reflection coefficient of the sensor for 21 fruits. The moisture content predicted by the sensor was in good agreement with that obtained using the standard oven drying method within ± 5% accuracy when tested on 145 different fruits samples.

  10. Geometrical constraint experimental determination of Raman lidar overlap profile.

    PubMed

    Li, Jian; Li, Chengcai; Zhao, Yiming; Li, Jing; Chu, Yiqi

    2016-06-20

    A simple experimental method to determine the overlap profile of Raman lidar is presented in this paper. Based on Mie and Raman backscattering signals and a geometrically constrained condition, the overlap profile of a Raman lidar system can be determined. Our approach simultaneously retrieves the lidar ratio of aerosols, which is one of the most important sources of uncertainty in the overlap profile determination. The results indicate that the overlap factor is significantly influenced by the lidar ratio in experimental methods. A representative case study indicates that the correction of the overlap profile obtained by this method is practical and feasible.

  11. An approach to an accurate determination of the energy spectrum of high-energy electron beams using magnetic spectrometry

    NASA Astrophysics Data System (ADS)

    Renner, F.; Schwab, A.; Kapsch, R.-P.; Makowski, Ch; Jannek, D.

    2014-03-01

    At the national metrology institute of Germany, the Physikalisch-Technische Bundesanstalt, a research accelerator for dosimetry in radiation therapy has been installed. Magnetic spectrometry is used to determine the spectrum of high-energy electrons generated by this accelerator. Regarding the intended experiments at the accelerator, a high accuracy for the energy determination of the electron beam is required. For this purpose, an experimental setup is used that has a number of additional devices assembled around the spectrometer to determine geometric characteristics of the electron beam, which influence the energy analysis. For the analysis of the acquired data, a software was developed which meets specific needs. One important aspect is that the software is based on an algorithm for energy determination which considers the measured magnetic flux density of the spectrometer and geometric details of the beam and the spectrometer. The software also meets the demand that it can be used to estimate the uncertainty assigned to the energy. This paper covers the experimental and analytical background of magnetic spectrometry at the high-energy beamline of PTB's research accelerator. A comparison of results calculated with the specific algorithm for energy determination which was developed for this experimental setup and with well-known algorithms is given to show the advantage of the specific method. Results of measurements and their analysis with the algorithm are presented as well.

  12. Use of Loran-C navigation system to accurately determine sampling site location in an above ground cooling reservoir

    SciTech Connect

    Lockwood, R.E.; Blankinship, D.R.

    1994-12-31

    Environmental monitoring programs often require accurate determination of sampling site locations in aquatic environments. This is especially true when a {open_quotes}picture{close_quotes} of high resolution is needed for observing a changing variable in a given area and location is assumed to be important to the distribution of that variable. Sample site location can be difficult if few visible land marks are available for reference on a large body of water. The use of navigational systems such as Global Positioning System (GPS) and its predecessor, Loran-C, provide an excellent method for sample site location. McFarland (1992) discusses the practicality of GPS for location determination. This article discusses the use of Loran-C in a sampling scheme implemented at the South Texas Project Electrical Generating Station (STPEGS), Wadsworth, Texas.

  13. An accurate method for determining residual stresses with magnetic non-destructive techniques in welded ferromagnetic steels

    NASA Astrophysics Data System (ADS)

    Vourna, P.

    2016-03-01

    The scope of the present research work was to investigate the proper selection criteria for developing a suitable methodology for the accurate determination of residual stresses existing in welded parts. Magnetic non-destructive testing took place by the use of two magnetic non-destructive techniques: by the measurement of the magnetic Barkhausen noise and by the evaluation of the magnetic hysteresis loop parameters. The spatial distribution of residual stresses in welded metal parts by both non-destructive magnetic methods and two diffraction methods was determined. The conduction of magnetic measurements required an initial calibration of ferromagnetic steels. Based on the examined volume of the sample, all methods used were divided into two large categories: the first one was related to the determination of surface residual stress, whereas the second one was related to bulk residual stress determination. The first category included the magnetic Barkhausen noise and the X-ray diffraction measurements, while the second one included the magnetic permeability and the neutron diffraction data. The residual stresses determined by the magnetic techniques were in a good agreement with the diffraction ones.

  14. Two-dimensional flow nanometry of biological nanoparticles for accurate determination of their size and emission intensity

    PubMed Central

    Block, Stephan; Fast, Björn Johansson; Lundgren, Anders; Zhdanov, Vladimir P.; Höök, Fredrik

    2016-01-01

    Biological nanoparticles (BNPs) are of high interest due to their key role in various biological processes and use as biomarkers. BNP size and composition are decisive for their functions, but simultaneous determination of both properties with high accuracy remains challenging. Optical microscopy allows precise determination of fluorescence/scattering intensity, but not the size of individual BNPs. The latter is better determined by tracking their random motion in bulk, but the limited illumination volume for tracking this motion impedes reliable intensity determination. Here, we show that by attaching BNPs to a supported lipid bilayer, subjecting them to hydrodynamic flows and tracking their motion via surface-sensitive optical imaging enable determination of their diffusion coefficients and flow-induced drifts, from which accurate quantification of both BNP size and emission intensity can be made. For vesicles, the accuracy of this approach is demonstrated by resolving the expected radius-squared dependence of their fluorescence intensity for radii down to 15 nm. PMID:27658367

  15. Experimental determination of thermal properties of alluvial soil

    NASA Astrophysics Data System (ADS)

    Kulkarni, N. G.; Bhandarkar, U. V.; Puranik, B. P.; Rao, A. B.

    2016-12-01

    In the present work, thermal conductivity and specific heat of a particular type of alluvial soil used in brick making in a certain region of India (Karad, Maharashtra State) are experimentally determined for later use in the estimation of ground heat loss in clamp type kilns. These properties are determined simultaneously using the steady-state and the transient temperature data measured in the setup constructed for this purpose. Additionally, physical properties of the soil are experimentally determined for use with six models for the prediction of the thermal conductivity of soil. The predictions from the models are compared with the experimental data. A separate data fitting exercise revealed a small temperature dependence of the soil thermal conductivity on the soil mean temperature.

  16. Active machine learning-driven experimentation to determine compound effects on protein patterns.

    PubMed

    Naik, Armaghan W; Kangas, Joshua D; Sullivan, Devin P; Murphy, Robert F

    2016-02-03

    High throughput screening determines the effects of many conditions on a given biological target. Currently, to estimate the effects of those conditions on other targets requires either strong modeling assumptions (e.g. similarities among targets) or separate screens. Ideally, data-driven experimentation could be used to learn accurate models for many conditions and targets without doing all possible experiments. We have previously described an active machine learning algorithm that can iteratively choose small sets of experiments to learn models of multiple effects. We now show that, with no prior knowledge and with liquid handling robotics and automated microscopy under its control, this learner accurately learned the effects of 48 chemical compounds on the subcellular localization of 48 proteins while performing only 29% of all possible experiments. The results represent the first practical demonstration of the utility of active learning-driven biological experimentation in which the set of possible phenotypes is unknown in advance.

  17. Accurate retention time determination of co-eluting proteins in analytical chromatography by means of spectral data.

    PubMed

    Dismer, Florian; Hansen, Sigrid; Oelmeier, Stefan Alexander; Hubbuch, Jürgen

    2013-03-01

    Chromatography is the method of choice for the separation of proteins, at both analytical and preparative scale. Orthogonal purification strategies for industrial use can easily be implemented by combining different modes of adsorption. Nevertheless, with flexibility comes the freedom of choice and optimal conditions for consecutive steps need to be identified in a robust and reproducible fashion. One way to address this issue is the use of mathematical models that allow for an in silico process optimization. Although this has been shown to work, model parameter estimation for complex feedstocks becomes the bottleneck in process development. An integral part of parameter assessment is the accurate measurement of retention times in a series of isocratic or gradient elution experiments. As high-resolution analytics that can differentiate between proteins are often not readily available, pure protein is mandatory for parameter determination. In this work, we present an approach that has the potential to solve this problem. Based on the uniqueness of UV absorption spectra of proteins, we were able to accurately measure retention times in systems of up to four co-eluting compounds. The presented approach is calibration-free, meaning that prior knowledge of pure component absorption spectra is not required. Actually, pure protein spectra can be determined from co-eluting proteins as part of the methodology. The approach was tested for size-exclusion chromatograms of 38 mixtures of co-eluting proteins. Retention times were determined with an average error of 0.6 s (1.6% of average peak width), approximated and measured pure component spectra showed an average coefficient of correlation of 0.992.

  18. Experimental determination of the dynamics of an acoustically levitated sphere

    SciTech Connect

    Pérez, Nicolás; Andrade, Marco A. B.; Canetti, Rafael; Adamowski, Julio C.

    2014-11-14

    Levitation of solids and liquids by ultrasonic standing waves is a promising technique to manipulate materials without contact. When a small particle is introduced in certain areas of a standing wave field, the acoustic radiation force pushes the particle to the pressure node. This movement is followed by oscillations of the levitated particle. Aiming to investigate the particle oscillations in acoustic levitation, this paper presents the experimental and numerical characterization of the dynamic behavior of a levitated sphere. To obtain the experimental response, a small sphere is lifted by the acoustic radiation force. After the sphere lift, it presents a damped oscillatory behavior, which is recorded by a high speed camera. To model this behavior, a mass-spring-damper system is proposed. In this model, the acoustic radiation force that acts on the sphere is theoretically predicted by the Gor'kov theory and the viscous forces are modeled by two damping terms, one term proportional to the square of the velocity and another term proportional to the particle velocity. The proposed model was experimentally verified by using different values of sound pressure amplitude. The comparison between numerical and experimental results shows that the model can accurately describe the oscillatory behavior of the sphere in an acoustic levitator.

  19. The Effect of Starspots on Accurate Radius Determination of the Low-Mass Double-Lined Eclipsing Binary Gu Boo

    NASA Astrophysics Data System (ADS)

    Windmiller, G.; Orosz, J. A.; Etzel, P. B.

    2010-04-01

    GU Boo is one of only a relatively small number of well-studied double-lined eclipsing binaries that contain low-mass stars. López-Morales & Ribas present a comprehensive analysis of multi-color light and radial velocity curves for this system. The GU Boo light curves presented by López-Morales & Ribas had substantial asymmetries, which were attributed to large spots. In spite of the asymmetry, López-Morales & Ribas derived masses and radii accurate to sime2%. We obtained additional photometry of GU Boo using both a CCD and a single-channel photometer and modeled the light curves with the ELC software to determine if the large spots in the light curves give rise to systematic errors at the few percent level. We also modeled the original light curves from the work of López-Morales & Ribas using models with and without spots. We derived a radius of the primary of 0.6329 ± 0.0026 R sun, 0.6413 ± 0.0049 R sun, and 0.6373 ± 0.0029 R sun from the CCD, photoelectric, and López-Morales & Ribas data, respectively. Each of these measurements agrees with the value reported by López-Morales & Ribas (R 1 = 0.623 ± 0.016 R sun) at the level of ≈2%. In addition, the spread in these values is ≈1%-2% from the mean. For the secondary, we derive radii of 0.6074 ± 0.0035 R sun, 0.5944 ± 0.0069 R sun, and 0.5976 ± 0.0059 R sun from the three respective data sets. The López-Morales & Ribas value is R 2 = 0.620 ± 0.020 R sun, which is ≈2%-3% larger than each of the three values we found. The spread in these values is ≈2% from the mean. The systematic difference between our three determinations of the secondary radius and that of López-Morales & Ribas might be attributed to differences in the modeling process and codes used. Our own fits suggest that, for GU Boo at least, using accurate spot modeling of a single set of multi-color light curves results in radii determinations accurate at the ≈2% level.

  20. Fast and accurate determination of the relative binding affinities of small compounds to HIV-1 protease using non-equilibrium work.

    PubMed

    Ngo, Son Tung; Hung, Huynh Minh; Nguyen, Minh Tho

    2016-12-05

    The fast pulling ligand (FPL) out of binding cavity using non-equilibrium molecular dynamics (MD) simulations was demonstrated to be a rapid, accurate and low CPU demand method for the determination of the relative binding affinities of a large number of HIV-1 protease (PR) inhibitors. In this approach, the ligand is pulled out of the binding cavity of the protein using external harmonic forces, and the work of pulling force corresponds to the relative binding affinity of HIV-1 PR inhibitor. The correlation coefficient between the pulling work and the experimental binding free energy of R=-0.95 shows that FPL results are in good agreement with experiment. It is thus easier to rank the binding affinities of HIV-1 PR inhibitors, that have similar binding affinities because the mean error bar of pulling work amounts to δW=7%. The nature of binding is discovered using the FPL approach. © 2016 Wiley Periodicals, Inc.

  1. Accurate determination of genetic identity for a single cacao bean, using molecular markers with a nanofluidic system, ensures cocoa authentication.

    PubMed

    Fang, Wanping; Meinhardt, Lyndel W; Mischke, Sue; Bellato, Cláudia M; Motilal, Lambert; Zhang, Dapeng

    2014-01-15

    Cacao (Theobroma cacao L.), the source of cocoa, is an economically important tropical crop. One problem with the premium cacao market is contamination with off-types adulterating raw premium material. Accurate determination of the genetic identity of single cacao beans is essential for ensuring cocoa authentication. Using nanofluidic single nucleotide polymorphism (SNP) genotyping with 48 SNP markers, we generated SNP fingerprints for small quantities of DNA extracted from the seed coat of single cacao beans. On the basis of the SNP profiles, we identified an assumed adulterant variety, which was unambiguously distinguished from the authentic beans by multilocus matching. Assignment tests based on both Bayesian clustering analysis and allele frequency clearly separated all 30 authentic samples from the non-authentic samples. Distance-based principle coordinate analysis further supported these results. The nanofluidic SNP protocol, together with forensic statistical tools, is sufficiently robust to establish authentication and to verify gourmet cacao varieties. This method shows significant potential for practical application.

  2. Heavy metal toxicity to bacteria - are the existing growth media accurate enough to determine heavy metal toxicity?

    PubMed

    Rathnayake, I V N; Megharaj, Mallavarapu; Krishnamurti, G S R; Bolan, Nanthi S; Naidu, Ravi

    2013-01-01

    A new minimal medium was formulated considering the limitations of the existing media for testing heavy metal sensitivity to bacteria. Toxicity of cadmium and copper to three bacteria was investigated in the new medium and compared with three other media commonly used to study the effect of the toxic metals. Based on speciation data arrived at using ion-selective electrodes, the available free-metal concentration in solution was highest in the MES-buffered medium. This finding was strongly supported by the estimated EC(50) values for the metals tested based on the toxicity bioassays. The free-ionic cadmium and copper concentrations in the medium provide more accurate determination of metal concentrations that affects the bacteria, than with most of other existing media. This will avoid doubts on other media and misleading conclusions relevant to the toxicity of heavy metals to bacteria and provides a better option for the study of metal-bacteria interactions.

  3. Determination of the experimental equilibrium structure of solid nitromethane using path-integral molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Reilly, Anthony M.; Habershon, Scott; Morrison, Carole A.; Rankin, David W. H.

    2010-03-01

    Path-integral molecular dynamics (PIMD) simulations with an empirical interaction potential have been used to determine the experimental equilibrium structure of solid nitromethane at 4.2 and 15 K. By comparing the time-averaged molecular structure determined in a PIMD simulation to the calculated minimum-energy (zero-temperature) molecular structure, we have derived structural corrections that describe the effects of thermal motion. These corrections were subsequently used to determine the equilibrium structure of nitromethane from the experimental time-averaged structure. We find that the corrections to the intramolecular and intermolecular bond distances, as well as to the torsion angles, are quite significant, particularly for those atoms participating in the anharmonic motion of the methyl group. Our results demonstrate that simple harmonic models of thermal motion may not be sufficiently accurate, even at low temperatures, while molecular simulations employing more realistic potential-energy surfaces can provide important insight into the role and magnitude of anharmonic atomic motions.

  4. Simple and accurate determination of global tau(R) in proteins using (13)C or (15)N relaxation data.

    PubMed

    Mispelter, J; Izadi-Pruneyre, N; Quiniou, E; Adjadj, E

    2000-03-01

    In the study of protein dynamics by (13)C or (15)N relaxation measurements different models from the Lipari-Szabo formalism are used in order to determine the motion parameters. The global rotational correlation time tau(R) of the molecule must be estimated prior to the analysis. In this Communication, the authors propose a new approach in determining an accurate value for tau(R) in order to realize the best fit of R(2) for the whole sequence of the protein, regardless of the different type of motions atoms may experience. The method first determines the highly structured regions of the sequence. For each corresponding site, the Lipari-Szabo parameters are calculated for R(1) and NOE, using an arbitrary value for tau(R). The chi(2) for R(2), summed over the selected sites, shows a clear minimum, as a function of tau(R). This minimum is used to better estimate a proper value for tau(R).

  5. Ion chromatography as highly suitable method for rapid and accurate determination of antibiotic fosfomycin in pharmaceutical wastewater.

    PubMed

    Zeng, Ping; Xie, Xiaolin; Song, Yonghui; Liu, Ruixia; Zhu, Chaowei; Galarneau, Anne; Pic, Jean-Stéphane

    2014-01-01

    A rapid and accurate ion chromatography (IC) method (limit of detection as low as 0.06 mg L(-1)) for fosfomycin concentration determination in pharmaceutical industrial wastewater was developed. This method was compared with the performance of high performance liquid chromatography determination (with a high detection limit of 96.0 mg L(-1)) and ultraviolet spectrometry after reacting with alizarin (difficult to perform in colored solutions). The accuracy of the IC method was established in the linear range of 1.0-15.0 mg L(-1) and a linear correlation was found with a correlation coefficient of 0.9998. The recoveries of fosfomycin from industrial pharmaceutical wastewater at spiking concentrations of 2.0, 5.0 and 8.0 mg L(-1) ranged from 81.91 to 94.74%, with a relative standard deviation (RSD) from 1 to 4%. The recoveries of effluent from a sequencing batch reactor treated fosfomycin with activated sludge at spiking concentrations of 5.0, 8.0, 10.0 mg L(-1) ranging from 98.25 to 99.91%, with a RSD from 1 to 2%. The developed IC procedure provided a rapid, reliable and sensitive method for the determination of fosfomycin concentration in industrial pharmaceutical wastewater and samples containing complex components.

  6. Flow Curve Determination at Large Plastic Strain Levels to Accurately Constitutive Equations of AHSS in Forming Simulation

    NASA Astrophysics Data System (ADS)

    Lemoine, X.; Sriram, S.; Kergen, R.

    2011-05-01

    ArcelorMittal continuously develops new steel grades (AHSS) with high performance for the automotive industry to improve the weight reduction and the passive safety. The wide market introduction of AHSS raises a new challenge for manufacturers in terms of material models in the prediction of forming—especially formability and springback. The relatively low uniform elongation, the high UTS and the low forming limit curve of these AHSS may cause difficulties in forming simulations. One of these difficulties is the consequence of the relatively low uniform elongation on the parameters identification of isotropic hardening model. Different experimental tests allow to reach large plastic strain levels (hydraulic bulge test, stack compression test, shear test…). After a description on how to determine the flow curve in these experimental tests, a comparison of the different flow curves is made for different steel grades. The ArcelorMittal identification protocol for hardening models is only based on stress-strain curves determined in uniaxial tension. Experimental tests where large plastic strain levels are reached are used to validate our identification protocol and to recommend some hardening models. Finally, the influence of isotropic hardening models and yield loci in forming prediction for AHSS steels will be presented.

  7. Method for experimental determination of flutter speed by parameter identification

    NASA Technical Reports Server (NTRS)

    Nissim, E.; Gilyard, Glenn B.

    1989-01-01

    A method for flight flutter testing is proposed which enables one to determine the flutter dynamic pressure from flights flown far below the flutter dynamic pressure. The method is based on the identification of the coefficients of the equations of motion at low dynamic pressures, followed by the solution of these equations to compute the flutter dynamic pressure. The initial results of simulated data reported in the present work indicate that the method can accurately predict the flutter dynamic pressure, as described. If no insurmountable difficulties arise in the implementation of this method, it may significantly improve the procedures for flight flutter testing.

  8. A tailored multi-frequency EPR approach to accurately determine the magnetic resonance parameters of dynamic nuclear polarization agents: application to AMUPol.

    PubMed

    Gast, P; Mance, D; Zurlo, E; Ivanov, K L; Baldus, M; Huber, M

    2017-02-01

    To understand the dynamic nuclear polarization (DNP) enhancements of biradical polarizing agents, the magnetic resonance parameters need to be known. We describe a tailored EPR approach to accurately determine electron spin-spin coupling parameters using a combination of standard (9 GHz), high (95 GHz) and ultra-high (275 GHz) frequency EPR. Comparing liquid- and frozen-solution continuous-wave EPR spectra provides accurate anisotropic dipolar interaction D and isotropic exchange interaction J parameters of the DNP biradical AMUPol. We found that D was larger by as much as 30% compared to earlier estimates, and that J is 43 MHz, whereas before it was considered to be negligible. With the refined data, quantum mechanical calculations confirm that an increase in dipolar electron-electron couplings leads to higher cross-effect DNP efficiencies. Moreover, the DNP calculations qualitatively reproduce the difference of TOTAPOL and AMUPol DNP efficiencies found experimentally and suggest that AMUPol is particularly effective in improving the DNP efficiency at magnetic fields higher than 500 MHz. The multi-frequency EPR approach will aid in predicting the optimal structures for future DNP agents.

  9. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates

    NASA Astrophysics Data System (ADS)

    Azurmendi, Hugo F.; Freedberg, Darón I.

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for 1DCC determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a 13C-13C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield 1JCC and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for JHH determinations, but adapted and extended to applications where, like in sugars, large one-bond 13C-13C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and oriented phases are very

  10. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates.

    PubMed

    Azurmendi, Hugo F; Freedberg, Darón I

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for (1)D(CC) determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a (13)C-(13)C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield (1)J(CC) and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for J(HH) determinations, but adapted and extended to applications where, like in sugars, large one-bond (13)C-(13)C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and

  11. Potassium determinations using SEM, FAAS and XRF: some experimental notes

    NASA Astrophysics Data System (ADS)

    Liritzis, I.; Mavrikis, D.; Zacharias, N.; Sakalis, A.; Tsirliganis, N.; Polymeris, G.S.

    The calibration of Scanning Electron Microscopy coupled with Energy Dispersive X- Rays Spec-trometry (SEM-EDS) for elemental quantitative analysis is an important task for characterization, provenance and absolute dating purposes. In particular the potassium determination is an im-portant contributor to dose rate assessments in luminescence and Electron Spin Resonance (ESR) dating. Here a SEM-EDX is calibrated on different archaeological and geoarchaeological materials against standard laboratory samples as well as measured by micro X-Rays Fluorescence (μXRF) and flame atomic absorption spectroscopy (FAAS) techniques. A common linear relationship is obtained for most elements and certain rock types used and two clear linear regressions for two types of rocks; one for granite, diorite, microgranite and sediments and another ceramic sherds, soils, marble schists, breccia. Such linear regressions become readily available for a future fast, efficient and accu-rate way of potassium determination.

  12. Accurate determination of peptide phosphorylation stoichiometry via automated diagonal capillary electrophoresis coupled with mass spectrometry: proof of principle.

    PubMed

    Mou, Si; Sun, Liangliang; Dovichi, Norman J

    2013-11-19

    While reversible protein phosphorylation plays an important role in many cellular processes, simple and reliable measurement of the stoichiometry of phosphorylation can be challenging. This measurement is confounded by differences in the ionization efficiency of phosphorylated and unphosphorylated sites during analysis by mass spectrometry. Here, we demonstrate diagonal capillary electrophoresis-mass spectrometry for the accurate determination of this stoichiometry. Diagonal capillary electrophoresis is a two-dimensional separation method that incorporates an immobilized alkaline phosphatase microreactor at the distal end of the first capillary and employs identical electrophoretic separation modes in both dimensions. The first dimension is used to separate a mixture of the phosphorylated and unphosphorylated forms of a peptide. Fractions are parked in the reactor where they undergo complete dephosphorylation. The products are then periodically transferred to the second capillary and analyzed by mass spectrometry (MS). Because the phosphorylated and unphosphorylated forms differ in charge, they are well resolved in the first dimension separation. Because the unphosphorylated and dephosphorylated peptides are identical, there is no bias in ionization efficiency, and phosphorylation stoichiometry can be determined by the ratio of the signal of the two forms. A calibration curve was generated from mixtures of a phosphorylated standard peptide and its unphosphorylated form, prepared in a bovine serum albumin tryptic digest. This proof of principle experiment demonstrated a linear response across nearly 2 orders of magnitude in stoichiometry.

  13. Experimental determination of satellite bolted joints thermal resistance

    NASA Technical Reports Server (NTRS)

    Mantelli, Marcia Barbosa Henriques; Basto, Jose Edson

    1990-01-01

    The thermal resistance was experimentally determined of the bolted joints of the first Brazilian satellite (SCD 01). These joints, used to connect the satellite structural panels, are reproduced in an experimental apparatus, keeping, as much as possible, the actual dimensions and materials. A controlled amount of heat is forced to pass through the joint and the difference of temperature between the panels is measured. The tests are conducted in a vacuum chamber with liquid nitrogen cooled walls, that simulates the space environment. Experimental procedures are used to avoid much heat losses, which are carefully calculated. Important observations about the behavior of the joint thermal resistance with the variation of the mean temperature are made.

  14. Method of fission heat flux determination from experimental data

    DOEpatents

    Paxton, Frank A.

    1999-01-01

    A method is provided for determining the fission heat flux of a prime specimen inserted into a specimen of a test reactor. A pair of thermocouple test specimens are positioned at the same level in the holder and a determination is made of various experimental data including the temperature of the thermocouple test specimens, the temperature of bulk water channels located in the test holder, the gamma scan count ratios for the thermocouple test specimens and the prime specimen, and the thicknesses of the outer clads, the fuel fillers, and the backclad of the thermocouple test specimen. Using this experimental data, the absolute value of the fission heat flux for the thermocouple test specimens and prime specimen can be calculated.

  15. Automated and quantitative headspace in-tube extraction for the accurate determination of highly volatile compounds from wines and beers.

    PubMed

    Zapata, Julián; Mateo-Vivaracho, Laura; Lopez, Ricardo; Ferreira, Vicente

    2012-03-23

    An automatic headspace in-tube extraction (ITEX) method for the accurate determination of acetaldehyde, ethyl acetate, diacetyl and other volatile compounds from wine and beer has been developed and validated. Method accuracy is based on the nearly quantitative transference of volatile compounds from the sample to the ITEX trap. For achieving that goal most methodological aspects and parameters have been carefully examined. The vial and sample sizes and the trapping materials were found to be critical due to the pernicious saturation effects of ethanol. Small 2 mL vials containing very small amounts of sample (20 μL of 1:10 diluted sample) and a trap filled with 22 mg of Bond Elut ENV resins could guarantee a complete trapping of sample vapors. The complete extraction requires 100 × 0.5 mL pumping strokes at 60 °C and takes 24 min. Analytes are further desorbed at 240 °C into the GC injector under a 1:5 split ratio. The proportion of analytes finally transferred to the trap ranged from 85 to 99%. The validation of the method showed satisfactory figures of merit. Determination coefficients were better than 0.995 in all cases and good repeatability was also obtained (better than 7% in all cases). Reproducibility was better than 8.3% except for acetaldehyde (13.1%). Detection limits were below the odor detection thresholds of these target compounds in wine and beer and well below the normal ranges of occurrence. Recoveries were not significantly different to 100%, except in the case of acetaldehyde. In such a case it could be determined that the method is not able to break some of the adducts that this compound forms with sulfites. However, such problem was avoided after incubating the sample with glyoxal. The method can constitute a general and reliable alternative for the analysis of very volatile compounds in other difficult matrixes.

  16. Experimental Inferential Structure Determination of Ensembles for Intrinsically Disordered Proteins.

    PubMed

    Brookes, David H; Head-Gordon, Teresa

    2016-04-06

    We develop a Bayesian approach to determine the most probable structural ensemble model from candidate structures for intrinsically disordered proteins (IDPs) that takes full advantage of NMR chemical shifts and J-coupling data, their known errors and variances, and the quality of the theoretical back-calculation from structure to experimental observables. Our approach differs from previous formulations in the optimization of experimental and back-calculation nuisance parameters that are treated as random variables with known distributions, as opposed to structural or ensemble weight optimization or use of a reference ensemble. The resulting experimental inferential structure determination (EISD) method is size extensive with O(N) scaling, with N = number of structures, that allows for the rapid ranking of large ensemble data comprising tens of thousands of conformations. We apply the EISD approach on singular folded proteins and a corresponding set of ∼25 000 misfolded states to illustrate the problems that can arise using Boltzmann weighted priors. We then apply the EISD method to rank IDP ensembles most consistent with the NMR data and show that the primary error for ranking or creating good IDP ensembles resides in the poor back-calculation from structure to simulated experimental observable. We show that a reduction by a factor of 3 in the uncertainty of the back-calculation error can improve the discrimination among qualitatively different IDP ensembles for the amyloid-beta peptide.

  17. Computational and Experimental Determination of Fragmentation for Naturally Fragmenting Warheads

    DTIC Science & Technology

    1981-05-01

    Table Page I Chemical analysis of Armco iron and HF-I steel ....................... 3 2 Summary of tensile-pull measurements for transverse-direction...ntered) REPORT DOCUMENTATION PAGE - E-EFORE COMTLETING FORM I REPORT NUMBER 2 GOVT ACCESSION NO. 3 RECIPIENT’S CATALOG NUMBERNSWC TR 80-238 4 TITLE (and...Sulbtitle) S TYPE OF REPORT & PERIOD COVERED COMPUTATIONAL AND EXPERIMENTAL 1 Final DETERMINATION OF FRAGMENTATION FOR NATURALLY FRAGMENTING WARHEADS

  18. Experimental determination of storage ring optics using orbit response measurements

    NASA Astrophysics Data System (ADS)

    Safranek, J.

    1997-02-01

    The measured response matrix giving the change in orbit at beam position monitors (BPMs) with changes in steering magnet excitation can be used to accurately calibrate the linear optics in an electron storage ring [1-8]. A computer code called LOCO (Linear Optics from Closed Orbits) was developed to analyze the NSLS X-Ray Ring measured response matrix to determine: the gradients in all 56 quadrupole magnets; the calibration of the steering magnets and BPMs; the roll of the quadrupoles, steering magnets, and BPMs about the electron beam direction; the longitudinal magnetic centers of the orbit steering magnets; the horizontal dispersion at the orbit steering magnets; and the transverse mis-alignment of the electron orbit in each of the sextupoles. Random orbit measurement error from the BPMs propagated to give only 0.04% rms error in the determination of individual quadrupole gradients and 0.4 mrad rms error in the determination of individual quadrupole rolls. Small variations of a few parts in a thousand in the quadrupole gradients within an individual family were resolved. The optics derived by LOCO gave accurate predictions of the horizontal dispersion, the beta functions, and the horizontal and vertical emittances, and it gave good qualitative agreement with the measured vertical dispersion. The improved understanding of the X-Ray Ring has enabled us to increase the synchrotron radiation brightness. The LOCO code can also be used to find the quadrupole family gradients that best correct for gradient errors in quadrupoles, in sextupoles, and from synchrotron radiation insertion devices. In this way the design periodicity of a storage ring's optics can be restored. An example of periodicity restoration will be presented for the NSLS VUV Ring. LOCO has also produced useful results when applied to the ALS storage ring [8].

  19. Accurate marker-free alignment with simultaneous geometry determination and reconstruction of tilt series in electron tomography.

    PubMed

    Winkler, Hanspeter; Taylor, Kenneth A

    2006-02-01

    An image alignment method for electron tomography is presented which is based on cross-correlation techniques and which includes a simultaneous refinement of the tilt geometry. A coarsely aligned tilt series is iteratively refined with a procedure consisting of two steps for each cycle: area matching and subsequent geometry correction. The first step, area matching, brings into register equivalent specimen regions in all images of the tilt series. It determines four parameters of a linear two-dimensional transformation, not just translation and rotation as is done during the preceding coarse alignment with conventional methods. The refinement procedure also differs from earlier methods in that the alignment references are now computed from already aligned images by reprojection of a backprojected volume. The second step, geometry correction, refines the initially inaccurate estimates of the geometrical parameters, including the direction of the tilt axis, a tilt angle offset, and the inclination of the specimen with respect to the support film or specimen holder. The correction values serve as an indicator for the progress of the refinement. For each new iteration, the correction values are used to compute an updated set of geometry parameters by a least squares fit. Model calculations show that it is essential to refine the geometrical parameters as well as the accurate alignment of the images to obtain a faithful map of the original structure.

  20. Stable isotope dilution assay for the accurate determination of mycotoxins in maize by UHPLC-MS/MS.

    PubMed

    Varga, Elisabeth; Glauner, Thomas; Köppen, Robert; Mayer, Katharina; Sulyok, Michael; Schuhmacher, Rainer; Krska, Rudolf; Berthiller, Franz

    2012-03-01

    A fast, easy-to-handle and cost-effective analytical method for 11 mycotoxins currently regulated in maize and other cereal-based food products in Europe was developed and validated for maize. The method is based on two extraction steps using different acidified acetonitrile–water mixtures. Separation is achieved using ultrahigh-performance liquid chromatography (UHPLC) by a linear water–methanol gradient. After electrospray ionisation, tandem mass spectrometric detection is performed in dynamic multiple reaction monitoring mode. Since accurate mass spectrometric quantification is hampered by matrix effects, uniformly [(13)C]-labelled mycotoxins for each of the 11 compounds were added to the sample extracts prior to UHPLC-MS/MS analysis. Method performance parameters were obtained by spiking blank maize samples with mycotoxins before as well as after extraction on six levels in triplicates. The twofold extraction led to total recoveries of the extraction steps between 97% and 111% for all target analytes, including fumonisins. The [(13)C]-labelled internal standards efficiently compensated all matrix effects in electrospray ionisation, leading to apparent recoveries between 88% and 105% with reasonable additional costs. The relative standard deviations of the whole method were between 4% and 11% for all analytes. The trueness of the method was verified by the measurement of several maize test materials with well-characterized concentrations. In conclusion, the developed method is capable of determining all regulated mycotoxins in maize and presuming similar matrix effects and extraction recovery also in other cereal-based foods.

  1. Accurate focal depth determination of oceanic earthquakes using water-column reverberation and some implications for the shrinking plate hypothesis

    NASA Astrophysics Data System (ADS)

    Huang, Jianping; Niu, Fenglin; Gordon, Richard G.; Cui, Chao

    2015-12-01

    Investigation of oceanic earthquakes is useful for constraining the lateral and depth variations of the stress and strain-rate fields in oceanic lithosphere, and the thickness of the seismogenic layer as a function of lithosphere age, thereby providing us with critical insight into thermal and dynamic processes associated with the cooling and evolution of oceanic lithosphere. With the goal of estimating hypocentral depths more accurately, we observe clear water reverberations after the direct P wave on teleseismic records of oceanic earthquakes and develop a technique to estimate earthquake depths by using these reverberations. The Z-H grid search method allows the simultaneous determination of the sea floor depth (H) and earthquake depth (Z) with an uncertainty less than 1 km, which compares favorably with alternative approaches. We apply this method to two closely located earthquakes beneath the eastern Pacific. These earthquakes occurred in ∼25 Ma-old lithosphere and were previously estimated to have similar depths of ∼10-12 km. We find that the two events actually occurred at dissimilar depths of 2.5 km and 16.8 km beneath the seafloor, respectively, within the oceanic crust and lithospheric mantle. The shallow and deep events are determined to be a thrust and normal earthquake, respectively, indicating that the stress field within the oceanic lithosphere changes from horizontal deviatoric compression to horizontal deviatoric tension as depth increases, which is consistent with the prediction of lithospheric cooling models. Furthermore, we show that the P-axis of the newly investigated thrust-faulting earthquake is perpendicular to that of the previously studied thrust event, consistent with the predictions of the shrinking-plate hypothesis.

  2. High Fidelity Non-Gravitational Force Models for Precise and Accurate Orbit Determination of TerraSAR-X

    NASA Astrophysics Data System (ADS)

    Hackel, Stefan; Montenbruck, Oliver; Steigenberger, -Peter; Eineder, Michael; Gisinger, Christoph

    Remote sensing satellites support a broad range of scientific and commercial applications. The two radar imaging satellites TerraSAR-X and TanDEM-X provide spaceborne Synthetic Aperture Radar (SAR) and interferometric SAR data with a very high accuracy. The increasing demand for precise radar products relies on sophisticated validation methods, which require precise and accurate orbit products. Basically, the precise reconstruction of the satellite’s trajectory is based on the Global Positioning System (GPS) measurements from a geodetic-grade dual-frequency receiver onboard the spacecraft. The Reduced Dynamic Orbit Determination (RDOD) approach utilizes models for the gravitational and non-gravitational forces. Following a proper analysis of the orbit quality, systematics in the orbit products have been identified, which reflect deficits in the non-gravitational force models. A detailed satellite macro model is introduced to describe the geometry and the optical surface properties of the satellite. Two major non-gravitational forces are the direct and the indirect Solar Radiation Pressure (SRP). Due to the dusk-dawn orbit configuration of TerraSAR-X, the satellite is almost constantly illuminated by the Sun. Therefore, the direct SRP has an effect on the lateral stability of the determined orbit. The indirect effect of the solar radiation principally contributes to the Earth Radiation Pressure (ERP). The resulting force depends on the sunlight, which is reflected by the illuminated Earth surface in the visible, and the emission of the Earth body in the infrared spectra. Both components of ERP require Earth models to describe the optical properties of the Earth surface. Therefore, the influence of different Earth models on the orbit quality is assessed within the presentation. The presentation highlights the influence of non-gravitational force and satellite macro models on the orbit quality of TerraSAR-X.

  3. Development and validation of a novel, simple, and accurate spectrophotometric method for the determination of lead in human serum.

    PubMed

    Shayesteh, Tavakol Heidari; Khajavi, Farzad; Khosroshahi, Abolfazl Ghafuri; Mahjub, Reza

    2016-01-01

    The determination of blood lead levels is the most useful indicator of the determination of the amount of lead that is absorbed by the human body. Various methods, like atomic absorption spectroscopy (AAS), have already been used for the detection of lead in biological fluid, but most of these methods are based on complicated, expensive, and highly instructed instruments. In this study, a simple and accurate spectroscopic method for the determination of lead has been developed and applied for the investigation of lead concentration in biological samples. In this study, a silica gel column was used to extract lead and eliminate interfering agents in human serum samples. The column was washed with deionized water. The pH was adjusted to the value of 8.2 using phosphate buffer, and then tartrate and cyanide solutions were added as masking agents. The lead content was extracted into the organic phase containing dithizone as a complexion reagent and the dithizone-Pb(II) complex was formed and approved by visible spectrophotometry at 538 nm. The recovery was found to be 84.6 %. In order to validate the method, a calibration curve involving the use of various concentration levels was calculated and proven to be linear in the range of 0.01-1.5 μg/ml, with an R (2) regression coefficient of 0.9968 by statistical analysis of linear model validation. The largest error % values were found to be -5.80 and +11.6 % for intra-day and inter-day measurements, respectively. The largest RSD % values were calculated to be 6.54 and 12.32 % for intra-day and inter-day measurements, respectively. Further, the limit of detection (LOD) was calculated to be 0.002 μg/ml. The developed method was applied to determine the lead content in the human serum of voluntary miners, and it has been proven that there is no statistically significant difference between the data provided from this novel method and the data obtained from previously studied AAS.

  4. Caregiver's Country of Birth Is a Significant Determinant of Accurate Perception of Preschool-Age Children's Weight

    ERIC Educational Resources Information Center

    Natale, Ruby; Uhlhorn, Susan B.; Lopez-Mitnik, Gabriela; Camejo, Stephanie; Englebert, Nicole; Delamater, Alan M.; Messiah, Sarah E.

    2016-01-01

    Background: One in four preschool-age children in the United States are currently overweight or obese. Previous studies have shown that caregivers of this age group often have difficulty accurately recognizing their child's weight status. The purpose of this study was to examine factors associated with accurate/inaccurate perception of child body…

  5. Experimental determination of material constants of a hybrid composite laminate

    SciTech Connect

    Ihekweazu, S.N.; Lari, S.B.; Unanwa, C.O.

    1999-07-01

    This paper discusses the results of the experimental study that was conducted in order to determine the material properties of a hybrid composite laminate made from Fiberite material MXM-7714/120 (a fabric prepreg consisting of woven Kevlar{reg_sign} 49 reinforcement impregnated with Fiberite 250 F (121 C) curing 7714 epoxy resin) and HYE-2448AIE (a 250 F (121 C) curing epoxy resin impregnated unidirectional graphite tape). First, each of the materials that comprise the hybrid laminate was fabricated separately according to ASTM-D-3039 specification in order to determine their material properties. The materials were then hybridized and the properties were determined. Data from this experiment reveal that a new class of material that can meet desired specifications can be created through hybridization. The data also revealed that the properties of the materials bonded together as a hybrid complement the properties of the constituent members of the hybrid.

  6. [Experimental determination of the absorption coefficients of biological tissues].

    PubMed

    Kovtun, A V; Kondrat'ev, V S; Terekhov, D V

    1980-01-01

    Procedure is presented for studying the coefficient of biological tissue absorption of radiation with the wavelength lambda = 1.06 mkm. The absorption coefficient is determined by the temperature values of biological tissue experimentally measured with thermopairs. The coherent radiation current falls on the surface of biological tissue. A mathematical model is formulated for biological tissue heating with radiation. Solution of Furier equation obtained by means of Green function is given. Using the relationship found, the energy absorbed by the biological tissue was calculated and the absorption coefficient of radiation with lambda - 1.06 mkm was determined. The results were analysed and the error of the obtained values of absorption coefficients of biological tissues under study were determined.

  7. Experimental Determination of Hydraulic Properties of Unsaturated Calcarenites

    NASA Astrophysics Data System (ADS)

    Turturro, Antonietta Celeste; Andriani, Gioacchino Francesco; Clementina Caputo, Maria; Maggi, Sabino

    2013-04-01

    Understanding hydraulic properties is essential in the modeling of flow and solute transport through the vadose zone, to which problems of soil and groundwater pollution are related. The vadose zone, in fact, is of great importance in controlling groundwater recharge and transport of contaminants into and through the subsoil. The aim of this work is to determine experimentally in laboratory the hydraulic properties of unsaturated calcarenites using an approach including petrophysical determinations and methods for measuring water retention. For this purpose, samples of calcarenites belonging to the Calcarenite di Gravina Fm.(Pliocene-early Pleistocene), came from two different quarry districts located in Southern Italy (Canosa di Puglia and Massafra), were utilized. The water retention function, θ(h), which binds the water content, θ, to water potential, h, was determined in the laboratory by means two different experimental methods: the WP4-T psychrometer and the suction table. At last, a simple mathematical equation represented by van Genuchten's model is fitted to the experimental data and the unknown empirical parameters of this model are determined. Textural analysis on thin sections using optical petrographic microscopy and evaluation of total and effective porosity by means of standard geotechnical laboratory tests, mercury intrusion porosimetry and image analysis were also performed. In particular, a comparison between mercury porosimetry data and results of photomicrograph computer analysis through the methods of quantitative stereology was employed for providing pore size distributions. The results of this study identify the relationship between the hydraulic behavior, described by the water retention function, and pore size distribution for the calcarenites that are not easy to hydraulically characterize. This relationship could represent a useful tool to infer the unsaturated hydraulic properties of calcarenites and in general this approach could be

  8. Experimentally Determined Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Watts, Carly; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vonau, Walt; Vogel, Matt; Conger, Bruce

    2015-01-01

    A Human-In-The-Loop (HITL) Portable Life Support System 2.0 (PLSS 2.0) test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014 to December 19, 2014. These closed-loop tests of the PLSS 2.0 system integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure but effluent water vapor from the Spacesuit Water Membrane Evaporator (SWME) and the Auxiliary Membrane Evaporator (Mini-ME), and effluent carbon dioxide from the Rapid Cycle Amine (RCA) were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the heat transfer coefficient (UA) of the Liquid Cooling Garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flowrate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit (EMU) LCG, the Oceaneering Space Systems (OSS) LCG, and the OSS auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.

  9. A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements

    NASA Astrophysics Data System (ADS)

    Chisham, G.; Freeman, M. P.

    2003-04-01

    Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1 2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year’s worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced

  10. Direct experimental determination of spectral densities of molecular complexes

    SciTech Connect

    Pachón, Leonardo A.; Brumer, Paul

    2014-11-07

    Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need to be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.

  11. An experimentally determined evolutionary model dramatically improves phylogenetic fit.

    PubMed

    Bloom, Jesse D

    2014-08-01

    All modern approaches to molecular phylogenetics require a quantitative model for how genes evolve. Unfortunately, existing evolutionary models do not realistically represent the site-heterogeneous selection that governs actual sequence change. Attempts to remedy this problem have involved augmenting these models with a burgeoning number of free parameters. Here, I demonstrate an alternative: Experimental determination of a parameter-free evolutionary model via mutagenesis, functional selection, and deep sequencing. Using this strategy, I create an evolutionary model for influenza nucleoprotein that describes the gene phylogeny far better than existing models with dozens or even hundreds of free parameters. Emerging high-throughput experimental strategies such as the one employed here provide fundamentally new information that has the potential to transform the sensitivity of phylogenetic and genetic analyses.

  12. Theoretical challenge to the experimentally determined geometrical structure of dimethylsilaethylene

    SciTech Connect

    Yoshioka, Yasunori; Goddard, John D.; Schaefer, III, Henry F.

    1981-05-01

    The equilibrium geometries of (CH3)2Si=CH2 and H{2Si=CH2 have been determined at the self-consistent-field level of electronic structure theory using a double zeta basis set augmented with d functions on all heavy atoms. For the parent silaethylene, large scale configuration interaction (6920 configurations) demonstrates that electron correlation effects do not qualitatively alter the predicted structure. Because of this, it is concluded that the experimental electron diffraction geometry of Mahaffy, Gutowsky, and Montgomery is likely to be seriously incorrect. Specifically the theoretical prediction for the dimethylsilaethylene Si=C distance is 1.692 Å, while the range of experimental values presented was 1.815 - 1.835 Å.

  13. Verification of Experimental Techniques for Flow Surface Determination

    NASA Technical Reports Server (NTRS)

    Lissenden, Cliff J.; Lerch, Bradley A.; Ellis, John R.; Robinson, David N.

    1996-01-01

    The concept of a yield surface is central to the mathematical formulation of a classical plasticity theory. However, at elevated temperatures, material response can be highly time-dependent, which is beyond the realm of classical plasticity. Viscoplastic theories have been developed for just such conditions. In viscoplastic theories, the flow law is given in terms of inelastic strain rate rather than the inelastic strain increment used in time-independent plasticity. Thus, surfaces of constant inelastic strain rate or flow surfaces are to viscoplastic theories what yield surfaces are to classical plasticity. The purpose of the work reported herein was to validate experimental procedures for determining flow surfaces at elevated temperatures. Since experimental procedures for determining yield surfaces in axial/torsional stress space are well established, they were employed -- except inelastic strain rates were used rather than total inelastic strains. In yield-surface determinations, the use of small-offset definitions of yield minimizes the change of material state and allows multiple loadings to be applied to a single specimen. The key to the experiments reported here was precise, decoupled measurement of axial and torsional strain. With this requirement in mind, the performance of a high-temperature multi-axial extensometer was evaluated by comparing its results with strain gauge results at room temperature. Both the extensometer and strain gauges gave nearly identical yield surfaces (both initial and subsequent) for type 316 stainless steel (316 SS). The extensometer also successfully determined flow surfaces for 316 SS at 650 C. Furthermore, to judge the applicability of the technique for composite materials, yield surfaces were determined for unidirectional tungsten/Kanthal (Fe-Cr-Al).

  14. Experimental determination of the emissivity coefficient of selected materials

    NASA Astrophysics Data System (ADS)

    Idzkowski, Adam; Walendziuk, Wojciech; Sawicki, Aleksander

    2016-09-01

    This paper concerns the experimental determination of the emissivity of selected materials (metals and alloys). In the first chapter the theoretical aspects are presented. Then ISO 18434-1:2008 norm, as the standard regulating all issues related to the emissivity and the way of its determination, is described. The aim of work was to modernize the laboratory stand for non-contact temperature measurements. The modernized laboratory stand was equipped with the modern data acquisition module (National Instruments NI 9203). It enabled to present temperature measurement data and to save it on the PC. As a result, students will be able to conduct more measurements and to make more conclusions about the emissivity of materials and its influence on a temperature result. Sample measurements and calculations were presented. The final element of study was to determine emissivity for each plate. It was made by calculations basing on the values: reference temperature (from Pt100 sensor) and non-contact temperature (from pyrometer). The emissivity values determined from these calculations were compared with the values obtained through published tables in the literature and with the values received by means of NEC Avio G100 thermographic camera. The expanded uncertainty of determined emissivity coefficient was also estimated.

  15. Membrane topology of transmembrane proteins: determinants and experimental tools.

    PubMed

    Lee, Hunsang; Kim, Hyun

    2014-10-17

    Membrane topology refers to the two-dimensional structural information of a membrane protein that indicates the number of transmembrane (TM) segments and the orientation of soluble domains relative to the plane of the membrane. Since membrane proteins are co-translationally translocated across and inserted into the membrane, the TM segments orient themselves properly in an early stage of membrane protein biogenesis. Each membrane protein must contain some topogenic signals, but the translocation components and the membrane environment also influence the membrane topology of proteins. We discuss the factors that affect membrane protein orientation and have listed available experimental tools that can be used in determining membrane protein topology.

  16. Accurate determination of ultra-trace levels of Ti in blood serum using ICP-MS/MS.

    PubMed

    Balcaen, Lieve; Bolea-Fernandez, Eduardo; Resano, Martín; Vanhaecke, Frank

    2014-01-27

    Ti is frequently used in implants and prostheses and it has been shown before that the presence of these in the human body can lead to elevated Ti concentrations in body fluids such as serum and urine. As identification of the exact mechanisms responsible for this increase in Ti concentrations, and the risks associated with it, are not fully understood, it is important to have sound analytical methods that enable straightforward quantification of Ti levels in body fluids (for both implanted and non-implanted individuals). Until now, only double-focusing sector field ICP-mass spectrometry (SF-ICP-MS) offered limits of detection that are good enough to deal with the very low basal levels of Ti in human serum. This work reports on the development of a novel method for the accurate and precise determination of trace levels of Ti in human serum samples, based on the use of ICP-MS/MS. O2 and NH3/He have been compared as reaction gases. While the use of O2 did not enable to overcome all spectral interferences, it has been shown that conversion of Ti(+) ions into Ti(NH3)6(+) cluster ions by using NH3/He as a reaction gas in an ICP-QQQ-MS system, operated in MS/MS mode, provided interference-free conditions and sufficiently low limits of detection, down to 3 ng L(-1) (instrumental detection limit obtained for the most abundant Ti isotope). The accuracy of the method proposed was evaluated by analysis of a Seronorm Trace Elements Serum L-1 reference material and by comparing the results obtained with those achieved by means of SF-ICP-MS. As a proof-of-concept, the newly developed method was successfully applied to the determination of Ti in serum samples obtained from individuals with and without Ti-based implants. All results were found to be in good agreement with those obtained by means of SF-ICP-MS. The typical basal Ti level in human serum was found to be <1 μg L(-1), while values in the range of 2-6 μg L(-1) were observed for implanted patients.

  17. Combining computer algorithms with experimental approaches permits the rapid and accurate identification of T cell epitopes from defined antigens.

    PubMed

    Schirle, M; Weinschenk, T; Stevanović, S

    2001-11-01

    The identification of T cell epitopes from immunologically relevant antigens remains a critical step in the development of vaccines and methods for monitoring of T cell responses. This review presents an overview of strategies that employ computer algorithms for the selection of candidate peptides from defined proteins and subsequent verification of their in vivo relevance by experimental approaches. Several computer algorithms are currently being used for epitope prediction of various major histocompatibility complex (MHC) class I and II molecules, based either on the analysis of natural MHC ligands or on the binding properties of synthetic peptides. Moreover, the analysis of proteasomal digests of peptides and whole proteins has led to the development of algorithms for the prediction of proteasomal cleavages. In order to verify the generation of the predicted peptides during antigen processing in vivo as well as their immunogenic potential, several experimental approaches have been pursued in the recent past. Mass spectrometry-based bioanalytical approaches have been used specifically to detect predicted peptides among isolated natural ligands. Other strategies employ various methods for the stimulation of primary T cell responses against the predicted peptides and subsequent testing of the recognition pattern towards target cells that express the antigen.

  18. Experimental determination of plastic strain in the extrusion process

    NASA Astrophysics Data System (ADS)

    Kronsteiner, J.; Horwatitsch, D.; Hinterer, A.; Gusenbauer, C.; Zeman, K.

    2016-10-01

    Simulating strain requires experimental validation. In this work, a method for the non-destructive determination of plastic strain in an extruded tube profile is presented. A copper coating, which deforms with the billet material, was used in the developed non-destructive method and was detected by computed tomography (CT) to analyze the deformation. The pattern was applied on cast billet halves (in the longitudinal direction) by a plasma coating technology. It was thus possible to determine the deformation of the pattern during the extrusion process in the billet as well as in the final profile without disassembling the extruded parts. A comparison of specimen using two different patterns shows the superiority of the simpler pattern consisting of only cross markers.

  19. Experimental determination of material damping using vibration analyzer

    NASA Technical Reports Server (NTRS)

    Chowdhury, Mostafiz R.; Chowdhury, Farida

    1990-01-01

    Structural damping is an important dynamic characteristic of engineering materials that helps to damp vibrations by reducing their amplitudes. In this investigation, an experimental method is illustrated to determine the damping characteristics of engineering materials using a dual channel Fast Fourier Transform (FFT) analyzer. A portable Compaq III computer which houses the analyzer, is used to collect the dynamic responses of three metal rods. Time-domain information is analyzed to obtain the logarithmic decrement of their damping. The damping coefficients are then compared to determine the variation of damping from material to material. The variations of damping from one point to another of the same material, due to a fixed point excitation, and the variable damping at a fixed point due to excitation at different points, are also demonstrated.

  20. Experimental determination of size distributions: analyzing proper sample sizes

    NASA Astrophysics Data System (ADS)

    Buffo, A.; Alopaeus, V.

    2016-04-01

    The measurement of various particle size distributions is a crucial aspect for many applications in the process industry. Size distribution is often related to the final product quality, as in crystallization or polymerization. In other cases it is related to the correct evaluation of heat and mass transfer, as well as reaction rates, depending on the interfacial area between the different phases or to the assessment of yield stresses of polycrystalline metals/alloys samples. The experimental determination of such distributions often involves laborious sampling procedures and the statistical significance of the outcome is rarely investigated. In this work, we propose a novel rigorous tool, based on inferential statistics, to determine the number of samples needed to obtain reliable measurements of size distribution, according to specific requirements defined a priori. Such methodology can be adopted regardless of the measurement technique used.

  1. Accurate laboratory determination of the near-infrared water vapor self-continuum: A test of the MT_CKD model

    NASA Astrophysics Data System (ADS)

    Campargue, A.; Kassi, S.; Mondelain, D.; Vasilchenko, S.; Romanini, D.

    2016-11-01

    The semi-empirical MT_CKD model of the absorption continuum of water vapor is widely used in atmospheric radiative transfer codes of the atmosphere of Earth and, recently, of exoplanets but lacks of experimental validation in the atmospheric windows. Recent laboratory measurements by Fourier transform Spectroscopy led to self-continuum cross sections much larger than the MT_CKD values in the near-infrared transparency windows. We report on accurate measurements by Cavity Ring Down Spectroscopy (CRDS) and Optical Feedback-Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) at selected spectral points of the transparency windows centered around 4.0, 2.1, and 1.25 µm. The temperature dependence of the absorption continuum at 4.38 µm is measured in the 23-39°C range. The self-continuum water vapor absorption is derived either from the baseline variation of water vapor spectra recorded for a series of pressure values over a small spectral interval or from baseline monitoring at fixed laser frequency during pressure ramps. After subtraction of the local water monomer lines contribution, self-continuum cross sections, Cs, are determined with an accuracy better than 10% from the pressure squared dependence of the continuum absorption measured up to about 15 Torr. Together with our previous measurements in the 2.1 and 1.6 µm windows, the present results provide a unique set of water vapor cross sections for testing the MT_CKD model in four transparency windows. Although showing some important deviations of the absolute values (up to about a factor 4), our accurate measurements validate the overall frequency dependence of the most recent version (V2.8) of the MT_CKD model.

  2. Accurate mass determination, quantification and determination of detection limits in liquid chromatography-high-resolution time-of-flight mass spectrometry: challenges and practical solutions.

    PubMed

    Vergeynst, Leendert; Van Langenhove, Herman; Joos, Pieter; Demeestere, Kristof

    2013-07-30

    Uniform guidelines for the data processing and validation of qualitative and quantitative multi-residue analysis using full-spectrum high-resolution mass spectrometry are scarce. Through systematic research, optimal mass accuracy and sensitivity are obtained after refining the post-processing of the HRMS data. For qualitative analysis, transforming the raw profile spectra to centroid spectra is recommended resulting in a 2.3 fold improved precision on the accurate mass determination of spectrum peaks. However, processing centroid data for quantitative purposes could lead to signal interruption when too narrow mass windows are applied for the construction of extracted ion chromatograms. Therefore, peak integration on the raw profile data is recommended. An optimal width of the mass window of 50 ppm, which is a trade-off between sensitivity and selectivity, was obtained for a TOF instrument providing a resolving power of 20,000 at full width at half maximum (FWHM). For the validation of HRMS analytical methods, widespread concepts such as the signal-to-noise ratios for the determination of decision limits and detection capabilities have shown to be not always applicable because in some cases almost no noise can be detected anymore. A statistical methodology providing a reliable alternative is extended and applied.

  3. Mass and position determination in MEMS mass sensors: a theoretical and an experimental investigation

    NASA Astrophysics Data System (ADS)

    Bouchaala, Adam; Nayfeh, Ali H.; Jaber, Nizar; Younis, Mohammad I.

    2016-10-01

    We present a method to determine accurately the position and mass of an entity attached to the surface of an electrostatically actuated clamped-clamped microbeam implemented as a mass sensor. In the theoretical investigation, the microbeam is modeled as a nonlinear Euler-Bernoulli beam and a perturbation technique is used to develop a closed-form expression for the frequency shift due to an added mass at a specific location on the microbeam surface. The experimental investigation was conducted on a microbeam made of Polyimide with a special lower electrode to excite both of the first and second modes of vibration. Using an ink-jet printer, we deposited droplets of polymers with a defined mass and position on the surface of the microbeam and we measured the shifts in its resonance frequencies. The theoretical predictions of the mass and position of the deposited droplets match well with the experimental measurements.

  4. Experimental determination of stress variation threshold resulted in earthquake triggering

    NASA Astrophysics Data System (ADS)

    Novikova, Elena; Novikov, Victor; Okunev, Vladimir; Klyuchkin, Vadim

    2014-05-01

    There are many field observations of earthquake triggering by static and dynamic stress variations caused by impact of distant strong earthquakes, underground chemical and nuclear explosions, solar-lunar earth tides, strong variations of atmospheric pressure etc., as well as by electric current injection into the Earth crust. It is supposed that the external impacts on the earthquake source result in exceeding the threshold stress and earthquake triggering. Nevertheless, the mechanisms of the earthquake triggering phenomena is not clear, and the problem of determination of stress variation threshold resulted in initiation of seismic events is very important. At present, based on analysis of field observations of dynamic triggering of earthquakes (by wave train from distant strong earthquakes) performed for various regions, including the USA, Japan, China, Greece, etc. it is considered that the triggering threshold of stress variations is about of 500 kPa. An experimental study at the spring-slider system was carried out for detailed study of behavior of fault area under near-to-failure state and experimental triggering impacts, as well as for determination of the threshold variation of normal stress in the fault gauge resulted in earthquake (slip) triggering. The spring-slider system provides a spring loading rate of 0.001 to 0.02 mm/s. The travelling block of dimensions 250x120x65 mm is connected with electromechanical drive via the spring with 9.5 N/mm spring constant. The normal stress of the travelling block is up to 30 kPa. For determination of the triggering threshold of normal stress variations the electromagnetic system was activated by control system at the level of 0.98-0.99 critical (fault failure) shear stress, which provided reducing the normal stress (by 0.001% to 0.1%) in the form of rectangular pulses of 0.5 to 5.0 s duration generated in time interval of 20 to 40 s. The level of stress variation impact resulted in the slip of travelling block (with

  5. Fast and accurate determination of K, Ca, and Mg in human serum by sector field ICP-MS.

    PubMed

    Yu, Lee L; Davis, W Clay; Nuevo Ordonez, Yoana; Long, Stephen E

    2013-11-01

    Electrolytes in serum are important biomarkers for skeletal and cellular health. The levels of electrolytes are monitored by measuring the Ca, Mg, K, and Na in blood serum. Many reference methods have been developed for the determination of Ca, Mg, and K in clinical measurements; however, isotope dilution thermal ionization mass spectrometry (ID-TIMS) has traditionally been the primary reference method serving as an anchor for traceability and accuracy to these secondary reference methods. The sample matrix must be separated before ID-TIMS measurements, which is a slow and tedious process that hindered the adoption of the technique in routine clinical measurements. We have developed a fast and accurate method for the determination of Ca, Mg, and K in serum by taking advantage of the higher mass resolution capability of the modern sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). Each serum sample was spiked with a mixture containing enriched (44)Ca, (26)Mg, and (41)K, and the (42)Ca(+):(44)Ca(+), (24)Mg(+):(26)Mg(+), and (39)K(+):(41)K(+) ratios were measured. The Ca and Mg ratios were measured in medium resolution mode (m/Δm ≈ 4 500), and the K ratio in high resolution mode (m/Δm ≈ 10 000). Residual (40)Ar(1)H(+) interference was still observed but the deleterious effects of the interference were minimized by measuring the sample at K > 100 ng g(-1). The interferences of Sr(++) at the two Ca isotopes were less than 0.25 % of the analyte signal, and they were corrected with the (88)Sr(+) intensity by using the Sr(++):Sr(+) ratio. The sample preparation involved only simple dilutions, and the measurement using this sample preparation approach is known as dilution-and-shoot (DNS). The DNS approach was validated with samples prepared via the traditional acid digestion approach followed by ID-SF-ICP-MS measurement. DNS and digested samples of SRM 956c were measured with ID-SF-ICP-MS for quality assurance, and the results (mean

  6. Active machine learning-driven experimentation to determine compound effects on protein patterns

    PubMed Central

    Naik, Armaghan W; Kangas, Joshua D; Sullivan, Devin P; Murphy, Robert F

    2016-01-01

    High throughput screening determines the effects of many conditions on a given biological target. Currently, to estimate the effects of those conditions on other targets requires either strong modeling assumptions (e.g. similarities among targets) or separate screens. Ideally, data-driven experimentation could be used to learn accurate models for many conditions and targets without doing all possible experiments. We have previously described an active machine learning algorithm that can iteratively choose small sets of experiments to learn models of multiple effects. We now show that, with no prior knowledge and with liquid handling robotics and automated microscopy under its control, this learner accurately learned the effects of 48 chemical compounds on the subcellular localization of 48 proteins while performing only 29% of all possible experiments. The results represent the first practical demonstration of the utility of active learning-driven biological experimentation in which the set of possible phenotypes is unknown in advance. DOI: http://dx.doi.org/10.7554/eLife.10047.001 PMID:26840049

  7. High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

    SciTech Connect

    Ng, Cheuk-Yiu

    2016-04-25

    The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

  8. Investigation of mass dependence effects for the accurate determination of molybdenum isotope amount ratios by MC-ICP-MS using synthetic isotope mixtures.

    PubMed

    Malinovsky, Dmitry; Dunn, Philip J H; Petrov, Panayot; Goenaga-Infante, Heidi

    2015-01-01

    Methodology for absolute Mo isotope amount ratio measurements by multicollector inductively coupled plasma-mass spectrometry (MC-ICP-MS) using calibration with synthetic isotope mixtures (SIMs) is presented. For the first time, synthetic isotope mixtures prepared from seven commercially available isotopically enriched molybdenum metal powders ((92)Mo, (94)Mo, (95)Mo, (96)Mo, (97)Mo, (98)Mo, and (100)Mo) are used to investigate whether instrumental mass discrimination of Mo isotopes in MC-ICP-MS is consistent with mass-dependent isotope distribution. The parent materials were dissolved and mixed as solutions to obtain mixtures with accurately known isotope amount ratios. The level of elemental impurities in the isotopically enriched molybdenum metal powders was quantified by ICP-MS by using both high-resolution and reaction cell instruments to completely resolve spectral interferences. The Mo isotope amount ratio values with expanded uncertainty (k = 2), determined by MC-ICP-MS for a high-purity Mo rod from Johnson Matthey, were as follows: (92)Mo/(95)Mo = 0.9235(9), (94)Mo/(95)Mo = 0.5785(8), (96)Mo/(95)Mo = 1.0503(9), (97)Mo/(95)Mo = 0.6033(6), (98)Mo/(95)Mo = 1.5291(20), and (100)Mo/(95)Mo = 0.6130(7). A full uncertainty budget for the measurements is presented which shows that the largest contribution to the uncertainty budget comes from correction for elemental impurities (∼51%), followed by the contribution from weighing operations (∼26 %). The atomic weight of molybdenum was calculated to be 95.947(2); the uncertainty in parentheses is expanded uncertainty with the coverage factor of 2. A particular advantage of the developed method is that calibration factors for all six Mo isotope amount ratios, involving the (95)Mo isotope, were experimentally determined. This allows avoiding any assumption on mass-dependent isotope fractions in MC-ICP-MS, inherent to the method of double spike previously used for Mo isotope amount ratio

  9. Experimentally Determined Interfacial Area Between Immiscible Fluids in Porous Media

    SciTech Connect

    Crandall, Dustin; Niessner, J; Hassanizadeh, S.M; Smith, Duane

    2008-01-01

    When multiple fluids flow through a porous medium, the interaction between the fluid interfaces can be of great importance. While this is widely recognized in practical applications, numerical models often disregard interactios between discrete fluid phases due to the computational complexity. And rightly so, for this level of detail is well beyond most extended Darcy Law relationships. A new model of two-phase flow including the interfacial area has been proposed by Hassarizadeh and Gray based upon thermodynamic principles. A version of this general equation set has been implemented by Nessner and Hassarizadeh. Many of the interfacial parameters required by this equation set have never been determined from experiments. The work presented here is a description of how the interfacial area, capillary pressure, interfacial velocity and interfacial permeability from two-phase flow experiments in porous media experiments can be used to determine the required parameters. This work, while on-going, has shown the possibility of digitizing images within translucent porous media and identifying the location and behavior of interfaces under dynamic conditions. Using the described methods experimentally derived interfacial functions to be used in larger scale simulations are currently being developed. In summary, the following conclusions can be drawn: (1) by mapping a pore-throat geometry onto an image of immiscible fluid flow, the saturation of fluids and the individual interfaces between the fluids can be identified; (2) the resulting saturation profiles of the low velocity drainage flows used in this study are well described by an invasion percolation fractal scaling; (3) the interfacial area between fluids has been observed to increase in a linear fashion during the initial invasion of the non-wetting fluid; and (4) the average capillary pressure within the entire cell and representative elemental volumes were observed to plateau after a small portion of the volume was

  10. Experimental determination of residence time distribution in continuous dry granulation.

    PubMed

    Mangal, Haress; Kleinebudde, Peter

    2017-03-31

    With increasing importance of continuous manufacturing, the interest in integrating dry granulation into a continuous manufacturing line is growing. Residence time distribution measurements are of importance as they provide information about duration of materials within the process. These data enable traceability and are highly beneficial for developing control strategies. A digital image analysis system was used to determine the residence time distribution of two materials with different deformation behavior (brittle, plastic) in the milling unit of dry granulation systems. A colorant was added to the material (20%w/w iron oxide), which did not affect the material properties excessively, so the milling process could be mimicked well. Experimental designs were conducted to figure out which parameters effect the mean residence time strongly. Moreover, two types of dry granulation systems were contrasted. Longer mean residence times were obtained for the oscillating mill (OM) compared to the conical mill (CM). For co-processed microcrystalline cellulose residence times of 19.8-44.4s (OM) and 11.6-29.1s (CM) were measured, mainly influenced by the specific compaction force, the mill speed and roll speed. For dibasic calcium phosphate anhydrate residence times from 17.7-46.4 (OM) and 5.4-10.2s (CM) were measured, while here the specific compaction force, the mill speed and their interactions with the roll speed had an influence on the mean residence time.

  11. Recent Experimental Advances to Determine (noble) Gases in Waters

    NASA Astrophysics Data System (ADS)

    Kipfer, R.; Brennwald, M. S.; Huxol, S.; Mächler, L.; Maden, C.; Vogel, N.; Tomonaga, Y.

    2013-12-01

    In aquatic systems noble gases, radon, and bio-geochemically conservative transient trace gases (SF6, CFCs) are frequently applied to determine water residence times and to reconstruct past environmental and climatic conditions. Recent experimental breakthroughs now enable ● to apply the well-established concepts of terrestrial noble gas geochemistry in waters to the minute water amounts stored in sediment pore space and in fluid inclusions (A), ● to determine gas exchange processes on the bio-geochemical relevant time scales of minutes - hours (B), and ● to separate diffusive and advective gas transport in soil air (C). A. Noble-gas analysis in water samples (< 1 g) facilitates determining the solute transport in the pore space and identifying the origin of bio- and geogenic fluids in (un) consolidated sediments [1]. Advanced techniques that combine crushing and sieving speleothem samples in ultra-high-vacuum to a specific grain size allow to separate air and water-bearing fluid inclusions and thus enables noble-gas-based reconstruction of environmental conditions from water masses as small as 1mg [2]. B. The coupling of noble gas analysis with approaches of gas chromatography permits combined analysis of noble gases and other gases species (e.g., SF6, CFCs, O2, N2) from a single water sample. The new method substantially improves ground water dating by SF6 and CFCs as excess air is quantified from the same sample and hence can adequately be corrected for [3]. Portable membrane-inlet mass spectrometers enable the quasi-continuous and real-time analysis of noble gases and other dissolved gases directly in the field, allowing, for instance, quantification of O2 turnover rates on small time scales [4]. C. New technical developments perfect 222Rn analysis in water by the synchronous the determination of the short-lived 220Rn. The combined 220,222Rn analysis sheds light on the emanation behaviour of radon by identifying soil water content to be the crucial

  12. Communication: Vibrationally resolved photoelectron spectroscopy of the tetracyanoquinodimethane (TCNQ) anion and accurate determination of the electron affinity of TCNQ

    NASA Astrophysics Data System (ADS)

    Zhu, Guo-Zhu; Wang, Lai-Sheng

    2015-12-01

    Tetracyanoquinodimethane (TCNQ) is widely used as an electron acceptor to form highly conducting organic charge-transfer solids. Surprisingly, the electron affinity (EA) of TCNQ is not well known and has never been directly measured. Here, we report vibrationally resolved photoelectron spectroscopy (PES) of the TCNQ- anion produced using electrospray and cooled in a cryogenic ion trap. Photoelectron spectrum taken at 354.7 nm represents the detachment transition from the ground state of TCNQ- to that of neutral TCNQ with a short vibrational progression. The EA of TCNQ is measured accurately to be 3.383 ± 0.001 eV (27 289 ± 8 cm-1), compared to the 2.8 ± 0.1 eV value known in the literature and measured previously using collisional ionization technique. In addition, six vibrational peaks are observed in the photoelectron spectrum, yielding vibrational frequencies for three totally symmetric modes of TCNQ. Two-photon PES via a bound electronic excited state of TCNQ- at 3.100 eV yields a broad low kinetic energy peak due to fast internal conversion to vibrationally excited levels of the anion ground electronic state. The high EA measured for TCNQ underlies its ability as a good electron acceptor.

  13. Communication: Vibrationally resolved photoelectron spectroscopy of the tetracyanoquinodimethane (TCNQ) anion and accurate determination of the electron affinity of TCNQ

    SciTech Connect

    Zhu, Guo-Zhu; Wang, Lai-Sheng

    2015-12-14

    Tetracyanoquinodimethane (TCNQ) is widely used as an electron acceptor to form highly conducting organic charge-transfer solids. Surprisingly, the electron affinity (EA) of TCNQ is not well known and has never been directly measured. Here, we report vibrationally resolved photoelectron spectroscopy (PES) of the TCNQ{sup −} anion produced using electrospray and cooled in a cryogenic ion trap. Photoelectron spectrum taken at 354.7 nm represents the detachment transition from the ground state of TCNQ{sup −} to that of neutral TCNQ with a short vibrational progression. The EA of TCNQ is measured accurately to be 3.383 ± 0.001 eV (27 289 ± 8 cm{sup −1}), compared to the 2.8 ± 0.1 eV value known in the literature and measured previously using collisional ionization technique. In addition, six vibrational peaks are observed in the photoelectron spectrum, yielding vibrational frequencies for three totally symmetric modes of TCNQ. Two-photon PES via a bound electronic excited state of TCNQ{sup −} at 3.100 eV yields a broad low kinetic energy peak due to fast internal conversion to vibrationally excited levels of the anion ground electronic state. The high EA measured for TCNQ underlies its ability as a good electron acceptor.

  14. Efficient implementation of the Hiller-Sucher-Feinberg identity for the accurate determination of the electron density

    NASA Astrophysics Data System (ADS)

    Challacombe, Matt; Cioslowski, Jerzy

    1994-01-01

    A new, highly optimized implementation of the Hiller-Sucher-Feinberg (HSF) identity is presented. The HSF identity, when applied to molecular wave functions calculated with Gaussian-type basis functions, not only improves the overall accuracy of the electron density by more than an order of magnitude, but also yields approximate cusps at nuclei. The three classes of molecular integrals, L, U, and V, which are encountered in the calculation of the HSF density, are derived in compact form. Efficient algorithms for the accurate evaluation of these integrals are detailed, including a novel approach to the necessary numerical quadratures and the thresholding of two-electron V integrals. Hartree-Fock (HF) electron densities calculated with both the conventional definition and from the HSF identity are compared to their respective HF limits for a variety of diatomic molecules and basis sets. The average error in the calculated HSF electron densities at non-hydrogen nuclei equals 0.17%, which constitutes a marked improvement over an error of 5.77% in the conventional densities.

  15. Communication: Vibrationally resolved photoelectron spectroscopy of the tetracyanoquinodimethane (TCNQ) anion and accurate determination of the electron affinity of TCNQ.

    PubMed

    Zhu, Guo-Zhu; Wang, Lai-Sheng

    2015-12-14

    Tetracyanoquinodimethane (TCNQ) is widely used as an electron acceptor to form highly conducting organic charge-transfer solids. Surprisingly, the electron affinity (EA) of TCNQ is not well known and has never been directly measured. Here, we report vibrationally resolved photoelectron spectroscopy (PES) of the TCNQ(-) anion produced using electrospray and cooled in a cryogenic ion trap. Photoelectron spectrum taken at 354.7 nm represents the detachment transition from the ground state of TCNQ(-) to that of neutral TCNQ with a short vibrational progression. The EA of TCNQ is measured accurately to be 3.383 ± 0.001 eV (27,289 ± 8 cm(-1)), compared to the 2.8 ± 0.1 eV value known in the literature and measured previously using collisional ionization technique. In addition, six vibrational peaks are observed in the photoelectron spectrum, yielding vibrational frequencies for three totally symmetric modes of TCNQ. Two-photon PES via a bound electronic excited state of TCNQ(-) at 3.100 eV yields a broad low kinetic energy peak due to fast internal conversion to vibrationally excited levels of the anion ground electronic state. The high EA measured for TCNQ underlies its ability as a good electron acceptor.

  16. Development of a Star Tracker-Based Reference System for Accurate Attitude Determination of a Simulated Spacecraft

    DTIC Science & Technology

    2012-03-01

    8 3 Typical Attitude Determination Process Flowchart . . . . . . . . . 9 4 Earth-Centered Inertial and...Plane Dimension vs. Vehicle Orientation - Flat Star Field . 87 2 Test 1 Mean Instrument Magnitude Data Across All Positions . . . 112 3 Test 2 Mean...Data Across All Positions . . . 119 8 Test 3 Mean Separation Angle Values Across All Positions . . . . . 122 9 Test 3 Algorithm Error Values

  17. Determination of accurate electron chiral asymmetries in fenchone and camphor in the VUV range: sensitivity to isomerism and enantiomeric purity.

    PubMed

    Nahon, Laurent; Nag, Lipsa; Garcia, Gustavo A; Myrgorodska, Iuliia; Meierhenrich, Uwe; Beaulieu, Samuel; Wanie, Vincent; Blanchet, Valérie; Géneaux, Romain; Powis, Ivan

    2016-05-14

    Photoelectron circular dichroism (PECD) manifests itself as an intense forward/backward asymmetry in the angular distribution of photoelectrons produced from randomly-oriented enantiomers by photoionization with circularly-polarized light (CPL). As a sensitive probe of both photoionization dynamics and of the chiral molecular potential, PECD attracts much interest especially with the recent performance of related experiments with visible and VUV laser sources. Here we report, by use of quasi-perfect CPL VUV synchrotron radiation and using a double imaging photoelectron/photoion coincidence (i(2)PEPICO) spectrometer, new and very accurate values of the corresponding asymmetries on showcase chiral isomers: camphor and fenchone. These data have additionally been normalized to the absolute enantiopurity of the sample as measured by a chromatographic technique. They can therefore be used as benchmarking data for new PECD experiments, as well as for theoretical models. In particular we found, especially for the outermost orbital of both molecules, a good agreement with CMS-Xα PECD modeling over the whole VUV range. We also report a spectacular sensitivity of PECD to isomerism for slow electrons, showing large and opposite asymmetries when comparing R-camphor to R-fenchone (respectively -10% and +16% around 10 eV). In the course of this study, we could also assess the analytical potential of PECD. Indeed, the accuracy of the data we provide are such that limited departure from perfect enantiopurity in the sample we purchased could be detected and estimated in excellent agreement with the analysis performed in parallel via a chromatographic technique, establishing a new standard of accuracy, in the ±1% range, for enantiomeric excess measurement via PECD. The i(2)PEPICO technique allows correlating PECD measurements to specific parent ion masses, which would allow its application to analysis of complex mixtures.

  18. Accurate determination of surface reference data in digital photographs in ice-free surfaces of Maritime Antarctica.

    PubMed

    Pina, Pedro; Vieira, Gonçalo; Bandeira, Lourenço; Mora, Carla

    2016-12-15

    The ice-free areas of Maritime Antarctica show complex mosaics of surface covers, with wide patches of diverse bare soils and rock, together with various vegetation communities dominated by lichens and mosses. The microscale variability is difficult to characterize and quantify, but is essential for ground-truthing and for defining classifiers for large areas using, for example high resolution satellite imagery, or even ultra-high resolution unmanned aerial vehicle (UAV) imagery. The main objective of this paper is to verify the ability and robustness of an automated approach to discriminate the variety of surface types in digital photographs acquired at ground level in ice-free regions of Maritime Antarctica. The proposed method is based on an object-based classification procedure built in two main steps: first, on the automated delineation of homogeneous regions (the objects) of the images through the watershed transform with adequate filtering to avoid an over-segmentation, and second, on labelling each identified object with a supervised decision classifier trained with samples of representative objects of ice-free surface types (bare rock, bare soil, moss and lichen formations). The method is evaluated with images acquired in summer campaigns in Fildes and Barton peninsulas (King George Island, South Shetlands). The best performances for the datasets of the two peninsulas are achieved with a SVM classifier with overall accuracies of about 92% and kappa values around 0.89. The excellent performances allow validating the adequacy of the approach for obtaining accurate surface reference data at the complete pixel scale (sub-metric) of current very high resolution (VHR) satellite images, instead of a common single point sampling.

  19. Accurate first-principles detailed-balance determination of auger recombination and impact ionization rates in semiconductors.

    PubMed

    Picozzi, S; Asahi, R; Geller, C B; Freeman, A J

    2002-11-04

    The technologically important prediction of Auger recombination lifetimes in semiconductors is addressed by means of a fully first-principles formalism, based on precise energy bands and wave functions provided by the full-potential linearized augmented plane wave code. The minority carrier Auger lifetime is determined by two related approaches: (i) a direct evaluation within Fermi's golden rule, and (ii) an indirect evaluation, based on a detailed balance formulation combining Auger recombination and its inverse process, impact ionization, in a unified framework. Lifetimes determined with the direct and indirect methods show excellent consistency between them (i) for n-doped GaAs and (ii) with measured values for GaAs and InGaAs. This indicates the computational formalism as a new sensitive tool for use in materials performance optimization.

  20. Accurate determination of electronic transport properties of silicon wafers by nonlinear photocarrier radiometry with multiple pump beam sizes

    SciTech Connect

    Wang, Qian; Li, Bincheng

    2015-12-07

    In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1–0.2 Ω·cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.

  1. Determination of accurate protein monoisotopic mass with the most abundant mass measurable using high-resolution mass spectrometry.

    PubMed

    Chen, Ya-Fen; Chang, C Allen; Lin, Yu-Hsuan; Tsay, Yeou-Guang

    2013-09-01

    While recent developments in mass spectrometry enable direct evaluation of monoisotopic masses (M(mi)) of smaller compounds, protein M(mi) is mostly determined based on its relationship to average mass (Mav). Here, we propose an alternative approach to determining protein M(mi) based on its correlation with the most abundant mass (M(ma)) measurable using high-resolution mass spectrometry. To test this supposition, we first empirically calculated M(mi) and M(ma) of 6158 Escherichia coli proteins, which helped serendipitously uncover a linear correlation between these two protein masses. With the relationship characterized, liquid chromatography-mass spectrometry was employed to measure M(ma) of protein samples in its ion cluster with the highest signal in the mass spectrum. Generally, our method produces a short series of likely M(mi) in 1-Da steps, and the probability of each likely M(mi) is assigned statistically. It is remarkable that the mass error of this M(mi) is as miniscule as a few parts per million, indicating that our method is capable of determining protein M(mi) with high accuracy. Benefitting from the outstanding performance of modern mass spectrometry, our approach is a significant improvement over others and should be of great utility in the rapid assessment of protein primary structures.

  2. Experimental methods of determining thermal properties of granite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determination of thermal properties of granite using the block method is discussed and compared with other methods. Problems that limit the accuracy of contact method in determining thermal properties of porous media are evaluated. Thermal properties of granite is determined in the laboratory with a...

  3. Innovations in Mass Spectrometry for Precise and Accurate Isotope Ratio Determination from Very Small Analyte Quantities (Invited)

    NASA Astrophysics Data System (ADS)

    Lloyd, N. S.; Bouman, C.; Horstwood, M. S.; Parrish, R. R.; Schwieters, J. B.

    2010-12-01

    This presentation describes progress in mass spectrometry for analysing very small analyte quantities, illustrated by example applications from nuclear forensics. In this challenging application, precise and accurate (‰) uranium isotope ratios are required from 1 - 2 µm diameter uranium oxide particles, which comprise less than 40 pg of uranium. Traditionally these are analysed using thermal ionisation mass spectrometry (TIMS), and more recently using secondary ionisation mass spectrometry (SIMS). Multicollector inductively-coupled plasma mass spectrometry (MC-ICP-MS) can offer higher productivity compared to these techniques, but is traditionally limited by low efficiency of analyte utilisation (sample through to ion detection). Samples can either be introduced as a solution, or sampled directly from solid using laser ablation. Large multi-isotope ratio datasets can help identify provenance and intended use of anthropogenic uranium and other nuclear materials [1]. The Thermo Scientific NEPTUNE Plus (Bremen, Germany) with ‘Jet Interface’ option offers unparalleled MC-ICP-MS sensitivity. An analyte utilisation of c. 4% has previously been reported for uranium [2]. This high-sensitivity configuration utilises a dry high-capacity (100 m3/h) interface pump, special skimmer and sampler cones and a desolvating nebuliser system. Coupled with new acquisition methodologies, this sensitivity enhancement makes possible the analysis of micro-particles and small sample volumes at higher precision levels than previously achieved. New, high-performance, full-size and compact discrete dynode secondary electron multipliers (SEM) exhibit excellent stability and linearity over a large dynamic range and can be configured to simultaneously measure all of the uranium isotopes. Options for high abundance-sensitivity filters on two ion beams are also available, e.g. for 236U and 234U. Additionally, amplifiers with high ohm (1012 - 1013) feedback resistors have been developed to

  4. Comparison of experimentally and theoretically determined radiation characteristics of photosynthetic microorganisms

    NASA Astrophysics Data System (ADS)

    Kandilian, Razmig; Pruvost, Jérémy; Artu, Arnaud; Lemasson, Camille; Legrand, Jack; Pilon, Laurent

    2016-05-01

    This paper aims to experimentally and directly validate a recent theoretical method for predicting the radiation characteristics of photosynthetic microorganisms. Such predictions would facilitate light transfer analysis in photobioreactors (PBRs) to control their operation and to maximize their production of biofuel and other high-value products. The state of the art experimental method can be applied to microorganisms of any shape and inherently accounts for their non-spherical and heterogeneous nature. On the other hand, the theoretical method treats the microorganisms as polydisperse homogeneous spheres with some effective optical properties. The absorption index is expressed as the weighted sum of the pigment mass absorption cross-sections and the refractive index is estimated based on the subtractive Kramers-Kronig relationship given an anchor refractive index and wavelength. Here, particular attention was paid to green microalgae Chlamydomonas reinhardtii grown under nitrogen-replete and nitrogen-limited conditions and to Chlorella vulgaris grown under nitrogen-replete conditions. First, relatively good agreement was found between the two methods for determining the mass absorption and scattering cross-sections and the asymmetry factor of both nitrogen-replete and nitrogen-limited C. reinhardtii with the proper anchor point. However, the homogeneous sphere approximation significantly overestimated the absorption cross-section of C. vulgaris cells. The latter were instead modeled as polydisperse coated spheres consisting of an absorbing core containing pigments and a non-absorbing but strongly refracting wall made of sporopollenin. The coated sphere approximation gave good predictions of the experimentally measured integral radiation characteristics of C. vulgaris. In both cases, the homogeneous and coated sphere approximations predicted resonance in the scattering phase function that were not observed experimentally. However, these approximations were

  5. The role of cognitive switching in head-up displays. [to determine pilot ability to accurately extract information from either of two sources

    NASA Technical Reports Server (NTRS)

    Fischer, E.

    1979-01-01

    The pilot's ability to accurately extract information from either one or both of two superimposed sources of information was determined. Static, aerial, color 35 mm slides of external runway environments and slides of corresponding static head-up display (HUD) symbology were used as the sources. A three channel tachistoscope was utilized to show either the HUD alone, the scene alone, or the two slides superimposed. Cognitive performance of the pilots was assessed by determining the percentage of correct answers given to two HUD related questions, two scene related questions, or one HUD and one scene related question.

  6. Accurate determination of lattice parameters based on Niggli reduced cell theory by using digitized electron diffraction micrograph.

    PubMed

    Yang, Yi; Cai, Canying; Lin, Jianguo; Gong, Lunjun; Yang, Qibin

    2017-05-01

    In this paper, we used Niggli reduced cell theory to determine lattice constants of a micro/nano crystal by using electron diffraction patterns. The Niggli reduced cell method enhanced the accuracy of lattice constant measurement obviously, because the lengths and the angles of lattice vectors of a primitive cell can be measured directly on the electron micrographs instead of a double tilt holder. With the aid of digitized algorithm and least square optimization by using three digitized micrographs, a valid reciprocal Niggli reduced cell number can be obtained. Thus a reciprocal and real Bravais lattices are acquired. The results of three examples, i.e., Mg4Zn7, an unknown phase (Precipitate phase in nickel-base superalloy) and Ba4Ti13O30 showed that the maximum errors are 1.6% for lengths and are 0.3% for angles.

  7. Accurate determination of ⁴¹Ca concentrations in spent resins from the nuclear industry by accelerator mass spectrometry.

    PubMed

    Nottoli, Emmanuelle; Bourlès, Didier; Bienvenu, Philippe; Labet, Alexandre; Arnold, Maurice; Bertaux, Maité

    2013-12-01

    The radiological characterisation of nuclear waste is essential for managing storage sites. Determining the concentration of Long-Lived RadioNuclides (LLRN) is fundamental for their long-term management. This paper focuses on the measurement of low (41)Ca concentrations in ions exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). (41)Ca concentrations were successfully measured by Accelerator Mass Spectrometry (AMS) after the acid digestion of resin samples, followed by radioactive decontamination and isobaric suppression through successive hydroxide, carbonate, nitrate and final CaF2 precipitations. Measured (41)Ca concentrations ranged from 0.02 to 0.03 ng/g, i.e. from 0.06 to 0.09 Bq/g. The (41)Ca/(60)Co activity ratios obtained were remarkably reproducible and in good agreement with the current ratio used for resins management.

  8. Experimental Determination of DT Yield in High Current DD Dense Plasma Focii

    SciTech Connect

    Lowe, D. R.; Hagen, E. C.; Meehan, B. T.; Springs, R. K.; O'Brien, R. J.

    2013-06-18

    Dense Plasma Focii (DPF), which utilize deuterium gas to produce 2.45 MeV neutrons, may in fact also produce DT fusion neutrons at 14.1 MeV due to the triton production in the DD reaction. If beam-target fusion is the primary producer of fusion neutrons in DPFs, it is possible that ejected tritons from the first pinch will interact with the second pinch, and so forth. The 2 MJ DPF at National Security Technologies’ Losee Road Facility is able to, and has produced, over 1E12 DD neutrons per pulse, allowing an accurate measurement of the DT/DD ratio. The DT/DD ratio was experimentally verified by using the (n,2n) reaction in a large piece of praseodymium metal, which has a threshold reaction of 8 MeV, and is widely used as a DT yield measurement system1. The DT/DD ratio was experimentally determined for over 100 shots, and then compared to independent variables such as tube pressure, number of pinches per shot, total current, pinch current and charge voltage.

  9. Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns

    PubMed Central

    Jawla, Sudheer K.; Nanni, Emilio A.; Shapiro, Michael A.; Woskov, Paul P.; Temkin, Richard J.

    2012-01-01

    This work focuses on the accuracy of the mode content measurements in an overmoded corrugated waveguide using measured radiated field patterns. Experimental results were obtained at 250 GHz using a vector network analyzer with over 70 dB of dynamic range. The intensity and phase profiles of the fields radiated from the end of the 19 mm diameter helically tapped brass waveguide were measured on planes at 7, 10, and 13 cm from the waveguide end. The measured fields were back propagated to the waveguide aperture to provide three independent estimates of the field at the waveguide exit aperture. Projecting that field onto the modes of the guide determined the waveguide mode content. The three independent mode content estimates were found to agree with one another to an accuracy of better than ±0.3%. These direct determinations of the mode content were compared with indirect measurements using the experimentally measured amplitude in three planes, with the phase determined by a phase retrieval algorithm. The phase retrieval technique using the planes at 7, 10, and 13 cm yielded a mode content estimate in excellent agreement, within 0.3%, of the direct measurements. Phase retrieval results using planes at 10, 20, and 30 cm were less accurate due to truncation of the measurement in the transverse plane. The reported measurements benefited greatly from a precise mechanical alignment of the scanner with respect to the waveguide axis. These results will help to understand the accuracy of mode content measurements made directly in cold test and indirectly in hot test using the phase retrieval technique. PMID:25264391

  10. Determination of nuclear level densities from experimental information

    SciTech Connect

    Cole, B.J. ); Davidson, N.J. , P.O. Box 88, Manchester M60 1QD ); Miller, H.G. )

    1994-10-01

    A novel information theory based method for determining the density of states from prior information is presented. The energy dependence of the density of states is determined from the observed number of states per energy interval, and model calculations suggest that the method is sufficiently reliable to calculate the thermal properties of nuclei over a reasonable temperature range.

  11. Accurate determination of ochratoxin A in Korean fermented soybean paste by isotope dilution-liquid chromatography tandem mass spectrometry.

    PubMed

    Ahn, Seonghee; Lee, Suyoung; Lee, Joonhee; Kim, Byungjoo

    2016-01-01

    Ochratoxin A (OTA), a naturally occurring mycotoxin, has been frequently detected in doenjang, a traditional fermented soybean paste, when it is fermented under improper conditions. Reliable screening of OTA in traditional fermented soybean paste (doenjang) is a special food-safety issue in Korea. Our laboratory, the National Metrology Institute of Korea, established an isotope dilution-liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method as a higher-order reference method to be used for SI-traceable value-assignment of OTA in certified reference materials (CRMs). (13)C20-OTA was used as an internal standard. Sample preparation conditions and LC/MS measurement parameters were optimised for this purpose. The analytical method was validated by measuring samples fortified with OTA at various levels. Repeatability and reproducibility studies showed that the ID-LC/MS/MS method is reliable and reproducible within 2% relative standard deviation. The analytical method was applied to determine OTA in various commercial doenjang products and home-made doenjang products.

  12. A validated spectrofluorimetric method for the determination of nifuroxazide through coumarin formation using experimental design

    PubMed Central

    2013-01-01

    Background Nifuroxazide (NF) is an oral nitrofuran antibiotic, having a wide range of bactericidal activity against gram positive and gram negative enteropathogenic organisms. It is formulated either in single form, as intestinal antiseptic or in combination with drotaverine (DV) for the treatment of gastroenteritis accompanied with gastrointestinal spasm. Spectrofluorimetry is a convenient and sensitive technique for pharmaceutical quality control. The new proposed spectrofluorimetric method allows its determination either in single form or in binary mixture with DV. Furthermore, experimental conditions were optimized using the new approach: Experimental design, which has many advantages over the old one, one variable at a time (OVAT approach). Results A novel and sensitive spectrofluorimetric method was designed and validated for the determination of NF in pharmaceutical formulation. The method was based upon the formation of a highly fluorescent coumarin compound by the reaction between NF and ethylacetoacetate (EAA) using sulfuric acid as catalyst. The fluorescence was measured at 390 nm upon excitation at 340 nm. Experimental design was used to optimize experimental conditions. Volumes of EAA and sulfuric acid, temperature and heating time were considered the critical factors to be studied in order to establish an optimum fluorescence. Each two factors were co-tried at three levels. Regression analysis revealed good correlation between fluorescence intensity and concentration over the range 20–400 ng ml-1. The suggested method was successfully applied for the determination of NF in pure and capsule forms. The procedure was validated in terms of linearity, accuracy, precision, limit of detection and limit of quantification. The selectivity of the method was investigated by analysis of NF in presence of the co-mixed drug DV where no interference was observed. The reaction pathway was suggested and the structure of the fluorescent product was proposed

  13. Experimental Program for the Determination of Hull Structural Damping Coefficients.

    DTIC Science & Technology

    1981-09-01

    experimental conditions must be recorded and presented as part of the data. Completeness requires that all factors related to the data must be measured...carrier, and a Ŕ,000 ton container ship). - 17. Ley Weds I. Distribution Steemen, Damping Document is available to the Hull vibrations public through the...Vibration ............................... 18 2.1.1.2 Forced Vibration Steady State ............... 19 2.1.1.3 Transient or Non- Harmonic Vibration

  14. Condensation of water vapor: Experimental determination of mass and thermal accommodation coefficients

    NASA Astrophysics Data System (ADS)

    Winkler, P. M.; Vrtala, A.; Rudolf, R.; Wagner, P. E.; Riipinen, I.; Vesala, T.; Lehtinen, K. E. J.; Viisanen, Y.; Kulmala, M.

    2006-10-01

    Experimental determinations of mass and thermal accommodation coefficients αm and αt for condensation of water vapor in air have been conducted covering a temperature range from about 250 to 290 K. For the first time, both coefficients have been determined directly and simultaneously. To this end, growth of water droplets in air has been observed at different total gas pressures ranging from about 1000 down to 100 hPa. Monodispersed seed particles have been used as condensation nuclei. After addition of water vapor with well-defined partial vapor pressure, supersaturation was achieved by adiabatic expansion in an expansion chamber. Most experiments reported in the present paper were performed at vapor saturation ratios ranging from 1.30 to 1.50. Monodispersed Ag particles with a diameter of 9 nm have been used as condensation nuclei, and for humidification a diffusion humidifier was applied. One experiment was performed at the saturation ratio of 1.02, which resembles conditions observed in the Earth's lower atmosphere. In this experiment, monodispersed DEHS particles with a diameter of 80 nm were used as condensation nuclei, and water vapor was generated by quantitative evaporation of a liquid jet. Droplet growth was monitored using the CAMS method. For determination of the accommodation coefficients, experimental droplet growth curves were compared to corresponding theoretical curves. Quantitative comparison was performed by varying the respective accommodation coefficient and the starting time of droplet growth in a two-parameter best fit procedure. Considering the uncertainty with respect to the starting time of droplet growth and the uncertainties of the experimental water vapor supersaturation, corresponding maximum errors have been determined. From the results obtained it can be stated that αt is larger than 0.85 over the whole considered temperature range. For 250-270 K, values of αm below 0.8 are excluded, and for higher temperatures up to 290 K we can

  15. Experimental Determination of Trace Element Partition Coefficients Between Zircon, Garnet and Melt

    NASA Astrophysics Data System (ADS)

    Taylor, R. J.; Harley, S. L.; Hinton, R. W.; Elphick, S.

    2007-12-01

    The problem of relating ages, as calculated by zircon U-Pb geochronology, to processes and hence geoological events is central to understanding mountain building and crustal evolution. Accurate P-T-t paths can only be produced if zircon growth can be linked to specific rock and mineral processes used to establish pressure and temperature values for metamorphic episodes. As a major metamorphic mineral in crustal events, garnet is widely used as a thermobarometric tool, and linking garnet growth to zircon formation could be used to refine the interpretation of U-Pb ages. Attempts to resolve this issue have focussed on REE partitioning between zircon and garnet, both of which strongly incorporate the HREE into their structure, and so it is possible there is a distinct REE partitioning signature which will highlight whether the two minerals have grown in equilibrium. There are two complementary methods to obtaining this information, empirical and experimental. Empirical methods of determining this signature using carefully selected rocks have proved troublesome, with a wide range of partitioning signatures found. This work has used experimental techniques to produce zircon-melt, garnet-melt and zircon-garnet-melt partition coefficients at a range of P-T conditions using synthetic materials. Zircon and garnet are grown in trace element equilibrium with a water-undersaturated granitic melt, which represents partial melts formed in the lower crust during anatexis. Temperature ranges from 850°C to 1000°C at a pressure of 5Kbar were produced using internally heated gas apparatus. Trace element concentrations were measured using SIMS analysis at the Ion Microprobe Facility at the University of Edinburgh. The experimental data produced will be applied to interpret chemical signatures in zircon in garnet-bearing metamorphic rocks, and will provide an objective basis for interpretation of the timing of growth or recrystallisation of zircon in many high-grade terrains.

  16. Experimental determination of the effective strong coupling constant

    SciTech Connect

    Alexandre Deur; Volker Burkert; Jian-Ping Chen; Wolfgang Korsch

    2007-07-01

    We extract an effective strong coupling constant from low Q{sup 2} data on the Bjorken sum. Using sum rules, we establish its Q{sup 2}-behavior over the complete Q{sup 2}-range. The result is compared to effective coupling constants extracted from different processes and to calculations based on Schwinger-Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constant and the calculations is not clear, the results agree surprisingly well.

  17. Accurate determination of the fine-structure intervals in the 3P ground states of C-13 and C-12 by far-infrared laser magnetic resonance

    NASA Technical Reports Server (NTRS)

    Cooksy, A. L.; Saykally, R. J.; Brown, J. M.; Evenson, K. M.

    1986-01-01

    Accurate values are presented for the fine-structure intervals in the 3P ground state of neutral atomic C-12 and C-13 as obtained from laser magnetic resonance spectroscopy. The rigorous analysis of C-13 hyperfine structure, the measurement of resonant fields for C-12 transitions at several additional far-infrared laser frequencies, and the increased precision of the C-12 measurements, permit significant improvement in the evaluation of these energies relative to earlier work. These results will expedite the direct and precise measurement of these transitions in interstellar sources and should assist in the determination of the interstellar C-12/C-13 abundance ratio.

  18. Crystal structure solution from experimentally determined atomic pair distribution functions

    SciTech Connect

    Juhas, P.; Granlund, L.; Gujarathi, S.R.; Duxbury, P.M.; Billinge, S.J.L.

    2010-05-25

    An extension of the Liga algorithm for structure solution from atomic pair distribution functions (PDFs), to handle periodic crystal structures with multiple elements in the unit cell, is described. The procedure is performed in three separate steps. First, pair distances are extracted from the experimental PDF. In the second step the Liga algorithm is used to find unit-cell sites consistent with these pair distances. Finally, the atom species are assigned over the cell sites by minimizing the overlap of their empirical atomic radii. The procedure has been demonstrated on synchrotron X-ray PDF data from 16 test samples. The structure solution was successful for 14 samples, including cases with enlarged supercells. The algorithm success rate and the reasons for the failed cases are discussed, together with enhancements that should improve its convergence and usability.

  19. An Experimental Investigation To Determine Interaction Between Rotating Bodies

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Volz, M. P.; Mazuruk, K.

    2003-01-01

    A brass (copper+zinc) wheel, with a 4-in diameter and 1.4 in thick, was used for this investigation. Ceramic ball bearings were used to safely spin the wheel up to 40,000 rpm. The wheel was also electrically insulated from the rest of the armature. For spinning, an air turbine was used. The rotational velocity was measured by two methods: (1) A simple strobe light and (2) a photodiode that detected laser beam pulses as they passed through a slot in the rotating shaft. The magnetic sensor is based on a giant magnetoresistivity, and consists of a balanced bridge circuitry. The position of the sensor was as close as possible to the rim of the wheel. The linear dimension of the sensor is approximately equal to 8 mm so that the offset from the surface is on the order of 15 percent. We did not use any goniometer system, so the accuracy of the angular position is not high, being estimated within a few degrees, with the main uncertainty being the direction of Earth's magnetic field. We attempted to fit the experimental data with the presented theory by selecting the best value for the electrical conductivity of the wheel. The results of this procedure are displayed, where the black dots represent experimental values. A slight misfit on the right shoulder can be due to slight angular misalignment from a 90 degree position. The obtained value for the resistivity is 43 n(OMEGA)m, which compares well with those listed. We can conclude, based on these measurements, that the proposed theory satisfactorily explains our experiments.

  20. Experimentally Determined Coordinates for Three MILS Hydrophones Near Ascension Island

    SciTech Connect

    Harben, P. E.; Hollfelder, J. R.; Rodgers, A. J.

    1999-11-19

    We conducted an airgun survey in the waters of Ascension Island in May 1999 to determine new locations and depths for three Missile Impact Location System (MILS) hydrophones (ASC23, ASC24, and ASC26) currently in use by the Prototype International Data Center (PIDC) and the National Data Center (NDC). The nominal and new locations are summarized in Table 1. Although not rigorous, errors in the new locations and depths are conservatively estimated to be less than 100 m. The hydrophones are either on or near the ocean bottom in all three cases. The new depths are consistent with the following: Direct-phase airgun arrivals; Bathymetry determined along the track of the ship used for this airgun survey; Reflected phases from the airgun data; and Depths given in the original hydrophone installation report.

  1. Experimental Determination of Infrared Extinction Coefficients of Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Spann, J. F., Jr.; Abbas, M. M.

    1998-01-01

    This technique is based on irradiating a single isolated charged dust particle suspended in balance by an electric field, and measuring the scattered radiation as a function of angle. The observed scattered intensity profile at a specific wavelength obtained for a dust particle of known composition is compared with Mie theory calculations, and the variable parameters relating to the particle size and complex refractive index are adjusted for a best fit between the two profiles. This leads to a simultaneous determination of the particle radius, the complex refractive index, and the scattering and extinction coefficients. The results of these experiments can be utilized to examine the IRAS and DIRBE (Diffuse Infrared Background Experiment) infrared data sets in order to determine the dust particle physical characteristics and distributions by using infrared models and inversion techniques. This technique may also be employed for investigation of the rotational bursting phenomena whereby large size cosmic and interplanetary particles are believed to fragment into smaller dust particles.

  2. Experimental Determination of Shock Structures in Hetrogeneous Layered Material Systems

    DTIC Science & Technology

    2005-07-19

    2004). The failure and ultimate strength of the composites were both reported to increase with strain rate. Haque et al. (2003) used SHPB technique...Sierakowski and Chaturvedi, 1997). These material systems can be engineered to have the same strength and stiffness as high- strength steels , yet they...Hugoniot curve of GRP were determined. The spall strength of GRP was also studied by conducting a series of both normal-impact and combined pressure

  3. First accurate experimental study of Mu reactivity from a state-selected reactant in the gas phase: the Mu + H2{1} reaction rate at 300 K

    NASA Astrophysics Data System (ADS)

    Bakule, Pavel; Sukhorukov, Oleksandr; Ishida, Katsuhiko; Pratt, Francis; Fleming, Donald; Momose, Takamasa; Matsuda, Yasuyuki; Torikai, Eiko

    2015-02-01

    This paper reports on the experimental background and methodology leading to recent results on the first accurate measurement of the reaction rate of the muonium (Mu) atom from a state-selected reactant in the gas phase: the Mu + H2\\{1\\}\\to MuH + H reaction at 300 K, and its comparison with rigorous quantum rate theory, Bakule et al (2012 J. Phys. Chem. Lett. 3 2755). Stimulated Raman pumping, induced by 532 nm light from the 2nd harmonic of a Nd:YAG laser, was used to produce H2 in its first vibrational (v = 1) state, H2\\{1\\}, in a single Raman/reaction cell. A pulsed muon beam (from ‘ISIS’, at 50 Hz) matched the 25 Hz repetition rate of the laser, allowing data taking in equal ‘Laser-On/Laser-Off’ modes of operation. The signal to noise was improved by over an order of magnitude in comparison with an earlier proof-of-principle experiment. The success of the present experiment also relied on optimizing the overlap of the laser profile with the extended stopping distribution of the muon beam at 50 bar H2 pressure, in which Monte Carlo simulations played a central role. The rate constant, found from the analysis of three separate measurements, which includes a correction for the loss of {{H}2}\\{1\\} concentration due to collisional relaxation with unpumped H2 during the time of each measurement, is {{k}Mu}\\{1\\} = 9.9[(-1.4)(+1.7)] × 10-13 cm3 s-1 at 300 K. This is in good to excellent agreement with rigorous quantum rate calculations on the complete configuration interaction/Born-Huang surface, as reported earlier by Bakule et al, and which are also briefly commented on herein.

  4. 13C-labeled gluconate tracing as a direct and accurate method for determining the pentose phosphate pathway split ratio in Penicillium chrysogenum.

    PubMed

    Kleijn, Roelco J; van Winden, Wouter A; Ras, Cor; van Gulik, Walter M; Schipper, Dick; Heijnen, Joseph J

    2006-07-01

    In this study we developed a new method for accurately determining the pentose phosphate pathway (PPP) split ratio, an important metabolic parameter in the primary metabolism of a cell. This method is based on simultaneous feeding of unlabeled glucose and trace amounts of [U-13C]gluconate, followed by measurement of the mass isotopomers of the intracellular metabolites surrounding the 6-phosphogluconate node. The gluconate tracer method was used with a penicillin G-producing chemostat culture of the filamentous fungus Penicillium chrysogenum. For comparison, a 13C-labeling-based metabolic flux analysis (MFA) was performed for glycolysis and the PPP of P. chrysogenum. For the first time mass isotopomer measurements of 13C-labeled primary metabolites are reported for P. chrysogenum and used for a 13C-based MFA. Estimation of the PPP split ratio of P. chrysogenum at a growth rate of 0.02 h(-1) yielded comparable values for the gluconate tracer method and the 13C-based MFA method, 51.8% and 51.1%, respectively. A sensitivity analysis of the estimated PPP split ratios showed that the 95% confidence interval was almost threefold smaller for the gluconate tracer method than for the 13C-based MFA method (40.0 to 63.5% and 46.0 to 56.5%, respectively). From these results we concluded that the gluconate tracer method permits accurate determination of the PPP split ratio but provides no information about the remaining cellular metabolism, while the 13C-based MFA method permits estimation of multiple fluxes but provides a less accurate estimate of the PPP split ratio.

  5. Extension of the AMBER force field for nitroxide radicals and combined QM/MM/PCM approach to the accurate determination of EPR parameters of DMPOH in solution

    PubMed Central

    Hermosilla, Laura; Prampolini, Giacomo; Calle, Paloma; García de la Vega, José Manuel; Brancato, Giuseppe; Barone, Vincenzo

    2015-01-01

    A computational strategy that combines both time-dependent and time-independent approaches is exploited to accurately model molecular dynamics and solvent effects on the isotropic hyperfine coupling constants of the DMPO-H nitroxide. Our recent general force field for nitroxides derived from AMBER ff99SB is further extended to systems involving hydrogen atoms in β-positions with respect to NO. The resulting force-field has been employed in a series of classical molecular dynamics simulations, comparing the computed EPR parameters from selected molecular configurations to the corresponding experimental data in different solvents. The effect of vibrational averaging on the spectroscopic parameters is also taken into account, by second order vibrational perturbation theory involving semi-diagonal third energy derivatives together first and second property derivatives. PMID:26584116

  6. The Experimental Determination of the Newtonian Constant of Gravitation

    NASA Astrophysics Data System (ADS)

    Parks, Harold

    2005-04-01

    Just over two hundred years ago in his most celebrated publication Henry Cavendish began the description of his experiment with the words, ``the apparatus is very simple.'' Today the techniques for determining G remain simple in principle. Yet in practice these experiments still present some of the most difficult challenges in precision measurement. I will discuss these challenges as well as two recent G experiments on which I have worked. The first is the BIPM torsion-strip balance and the other is the JILA suspended Fabry-Perot cavity.

  7. Experimental determination of cavitation thresholds in liquid water and mercury

    SciTech Connect

    Taleyarkhan, R.P.; West, C.D.; Moraga, F.

    1998-11-01

    An overview is provided on cavitation threshold measurement experiments for water and mercury. Various aspects to be considered that affect onset determination are discussed along with design specifications developed for construction of appropriate apparatus types. Both static and transient-cavitation effects were studied using radically different apparatus designs. Preliminary data are presented for cavitation thresholds for water and mercury over a range of temperatures in static and high-frequency environments. Implications and issues related to spallation neutron source target designs and operation are discussed.

  8. First experimental determination of the solubility constant of coffinite

    NASA Astrophysics Data System (ADS)

    Szenknect, Stephanie; Mesbah, Adel; Cordara, Théo; Clavier, Nicolas; Brau, Henri-Pierre; Le Goff, Xavier; Poinssot, Christophe; Ewing, Rodney C.; Dacheux, Nicolas

    2016-05-01

    Dissolution experiments have been performed in order to determine the solubility constant of coffinite, USiO4. Several assemblages of phases were used in under-saturated experiments performed in 0.1 mol L-1 HCl under Ar atmosphere, as well as in air. These samples were fully-characterized and were composed of either USiO4, solely, or USiO4 and additional oxide byproducts that resulted from the synthesis procedure. The solubility constant of coffinite was determined at 25 °C and 1 bar (log *KS°(USiO4, cr) = -5.25 ± 0.05), as well as the standard free energy of formation of coffinite (ΔfG°(298 K) = -1867.6 ± 3.2 kJ mol-1), which enables one to infer the relative stability of coffinite and uraninite as a function of groundwater composition. Geochemical simulations using PHREEQC 2 software and the Thermochimie data base indicate that coffinite precipitates at 25 °C under reducing conditions, at pH = 6, for H4SiO4(aq) concentration of 7 × 10-5 mol L-1 and U(OH)4(aq) concentration of 10-11 mol L-1. The ΔfG° value determined was used to calculate the standard free energy associated with the formation of coffinite from a mixture of uraninite and quartz. The value obtained (Δr,oxG° = 20.6 ± 5.2 kJ mol-1) indicates unambiguously that coffinite is less stable than the quartz + uraninite mixture at 25 °C. Geochemical simulations using PHREEQC 2 software indicate that coffinite precipitates in solutions supersaturated with respect to UO2(cr), but undersaturated with respect to UO2(am) in aqueous solutions with silica concentrations typical of groundwater. These favorable conditions during the formation of sedimentary uranium ore deposits, as well as slow dissolution kinetics, explain the common occurrence of coffinite.

  9. A Experimental Determination of the Phases of Mosaic Centrosymmetric Crystals.

    NASA Astrophysics Data System (ADS)

    Gong, Ping-Po.

    Bragg reflections, in a Renninger type setup, have been used as primary beams in an investigation of the x-ray phase effect in simultaneous n-beam diffraction. The major part of the study involves the analysis of the simultaneous diffraction patterns of centrosymmetric crystals of germanium, silicon and zinc tungstate using n-beam dynamical theory of x-ray diffraction. The germanium and silicon crystals which we used were perfect while the zinc tungstate crystal was definitely mosaic in character. In the analysis, the general shapes, i.e. the intensity maxima and minima of the n-beam diffraction peaks can be explained in terms of abrupt variations of the absorption coefficients across the three- or four-beam regions. The behavior of these absorption coefficients can be understood on the basis of analysis of the general shapes of the dispersion surfaces which in turn, can be estimated at the n-beam point by using an approximated approach due to Post (1977). This approach ignores polarization effects, and therefore greatly simplifies the analysis of three- and four-beam diffraction effects. It is relatively straightforward to obtain useful x-ray phase information from both three- and four-beam diffractions for centrosymmetric crystals. The actual phase determination is based on qualitative observation of the location of the resonance type minimum in the n -beam interaction relative to the maximum of the interaction. The invariant triplet phase may be considered to be positive if the minimum is, say, to the right of the maximum on the diffraction chart and negative if it appears to the left of the maximum. It is necessary to consider reflection triplets which are "entering" the Ewald sphere separately from those that are "leaving". Clearly, a triplet which yields a positive invariant phase indication in an "entering" case, would yield a negative phase indication in a "leaving" case. The latter type are corrected for that effect. About one hundred and ten invariant

  10. Experimental Determination of Exhaust Gas Thrust, Special Report

    NASA Technical Reports Server (NTRS)

    Pinkel, Benjamin; Voss, Fred

    1940-01-01

    This investigation presents the results of tests made on a radial engine to determine the thrust that can be obtained from the exhaust gas when discharged from separate stacks and when discharged from the collector ring with various discharge nozzles. The engine was provided with a propeller to absorb the power and was mounted on a test stand equipped with scales for measuring the thrust and engine torque. The results indicate that at full open throttle at sea level, for the engine tested, a gain in thrust horsepower of 18 percent using separate stacks, and 9.5 percent using a collector ring and discharge nozzle, can be expected at an air speed of 550 miles per hour.

  11. Determining Pressure and Velocity Fields from Experimental Schlieren Data

    NASA Astrophysics Data System (ADS)

    Lee, Frank M.; Allshouse, Michael R.; Morrison, P. J.; Swinney, Harry L.

    2015-11-01

    Internal gravity waves generated by tidal flow over bottom topography in the ocean are important because they contribute significantly to the energy composition of the ocean. Determination of the instantaneous internal wave energy flux requires knowledge of the pressure and velocity fields, each of which is difficult to measure in the ocean or the laboratory. However, the density perturbation field can be measured using a laboratory technique known as ``synthetic schlieren.'' We present an analytical method for deducing both the pressure and velocity fields from the density perturbation field. This yields the instantaneous energy flux of linear internal waves. Our method is verified in tests with data from a Navier-Stokes direct numerical simulation. The method is then applied to laboratory schlieren data obtained for the conditions in the numerical simulations. MRA and HLS were supported by ONR. FML and PJM supported by DOE contract DE-FG02-04ER-54742.

  12. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

    DOE PAGES

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl– with the bulk-supporting electrolytes, based on the Pitzer model. The model developed inmore » this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.« less

  13. Accurate determination of ultra-trace impurities, including europium, in ultra-pure barium carbonate materials through inductively coupled plasma-tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wu, Shuchao; Zeng, Xiangcheng; Dai, Xuefeng; Hu, Yongping; Li, Gang; Zheng, Cunjiang

    2016-09-01

    Impurities, especially ultra-trace europium (Eu), in ultra-pure barium carbonate materials were accurately determined through inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS). Two reaction modes, namely, mass shift (with O2 as reaction gas) and on-mass modes(with NH3/He and He as reaction gases), were extensively investigated using Eu+ as target analyte. The use of Eu+ → EuO2+, instead of Eu+ → EuO+, as ion pairs in mass shift mode eliminated polyatomic interferences based on Ba matrix ions (135Ba16O2+ on 151Eu16O+ and 137Ba16O2+ on 153Eu16O+). This procedure exhibited enhanced sensitivity and selectivity. When the ICP-MS/MS was operated in NH3 on-mass mode, Eu+ can be determined in its original mass in interference-free conditions because NH3 did not react with Eu+ but with BaO+ to form a neutral product (BaO). The two reaction modes, especially NH3 on mass mode, were validated to be accurate because their resultant isotope ratios of 153Eu/151Eu matched well with that of the natural abundance ratio. The proposed ICP-MS/MS method is a sensitive technique with a limit of detection as low as 2.0 ng L- 1 for 153Eu+. Compared with conventional single-quadrupole (SQ) ICP-MS, both NH3 on-mass mode and O2 mass shift mode in ICP-MS/MS can be used to accurately determine Eu+ in ultra-pure BaCO3 materials. The detected concentration of Eu+ was 4.0 ng L- 1 to 15 ng L- 1, with spiked recoveries ranging from 100%-110%. ICP-MS/MS was also used to eliminate polyatomic interferences, particularly Ba-based interferences, prior to measurement of Gd and Sm. Impurities, including Na, Mg, Al, K, Mn, Fe, Cr, Sr, and Cs, in ultra-pure BaCO3 materials were also determined using ICP-MS/MS in conventional SQ mode.

  14. On the Experimental Determination of the One-Way Speed of Light

    ERIC Educational Resources Information Center

    Perez, Israel

    2011-01-01

    In this paper the question of the isotropy of the one-way speed of light is addressed from an experimental perspective. In particular, we analyse two experimental methods commonly used in its determination. The analysis is aimed at clarifying the view that the one-way speed of light cannot be determined by techniques in which physical entities…

  15. Experimentally determined spectral optimization for dedicated breast computed tomography

    SciTech Connect

    Prionas, Nicolas D.; Huang, Shih-Ying; Boone, John M.

    2011-02-15

    Purpose: The current study aimed to experimentally identify the optimal technique factors (x-ray tube potential and added filtration material/thickness) to maximize soft-tissue contrast, microcalcification contrast, and iodine contrast enhancement using cadaveric breast specimens imaged with dedicated breast computed tomography (bCT). Secondarily, the study aimed to evaluate the accuracy of phantom materials as tissue surrogates and to characterize the change in accuracy with varying bCT technique factors. Methods: A cadaveric breast specimen was acquired under appropriate approval and scanned using a prototype bCT scanner. Inserted into the specimen were cylindrical inserts of polyethylene, water, iodine contrast medium (iodixanol, 2.5 mg/ml), and calcium hydroxyapatite (100 mg/ml). Six x-ray tube potentials (50, 60, 70, 80, 90, and 100 kVp) and three different filters (0.2 mm Cu, 1.5 mm Al, and 0.2 mm Sn) were tested. For each set of technique factors, the intensity (linear attenuation coefficient) and noise were measured within six regions of interest (ROIs): Glandular tissue, adipose tissue, polyethylene, water, iodine contrast medium, and calcium hydroxyapatite. Dose-normalized contrast to noise ratio (CNRD) was measured for pairwise comparisons among the six ROIs. Regression models were used to estimate the effect of tube potential and added filtration on intensity, noise, and CNRD. Results: Iodine contrast enhancement was maximized using 60 kVp and 0.2 mm Cu. Microcalcification contrast and soft-tissue contrast were maximized at 60 kVp. The 0.2 mm Cu filter achieved significantly higher CNRD for iodine contrast enhancement than the other two filters (p=0.01), but microcalcification contrast and soft-tissue contrast were similar using the copper and aluminum filters. The average percent difference in linear attenuation coefficient, across all tube potentials, for polyethylene versus adipose tissue was 1.8%, 1.7%, and 1.3% for 0.2 mm Cu, 1.5 mm Al, and 0.2 mm

  16. Determination of Experimental Fuel Rod Parameters using 3D Modelling of PCMI with MPS Defect

    SciTech Connect

    Casagranda, Albert; Spencer, Benjamin Whiting; Pastore, Giovanni; Novascone, Stephen Rhead; Hales, Jason Dean; Williamson, Richard L; Martineau, Richard Charles

    2016-05-01

    An in-reactor experiment is being designed in order to validate the pellet-cladding mechanical interaction (PCMI) behavior of the BISON fuel performance code. The experimental parameters for the test rod being placed in the Halden Research Reactor are being determined using BISON simulations. The 3D model includes a missing pellet surface (MPS) defect to generate large local cladding deformations, which should be measureable after typical burnup times. The BISON fuel performance code is being developed at Idaho National Laboratory (INL) and is built on the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework. BISON supports both 2D and 3D finite elements and solves the fully coupled equations for solid mechanics, heat conduction and species diffusion. A number of fuel performance effects are included using models for swelling, densification, creep, relocation and fission gas production & release. In addition, the mechanical and thermal contact between the fuel and cladding is explicitly modelled using a master-slave based contact algorithm. In order to accurately predict PCMI effects, the BISON code includes the relevant physics involved and provides a scalable and robust solution procedure. The depth of the proposed MPS defect is being varied in the BISON model to establish an optimum value for the experiment. The experiment will be interrupted approximately every 6 months to measure cladding radial deformation and provide data to validate BISON. The complete rodlet (~20 discrete pellets) is being simulated using a 180° half symmetry 3D model with MPS defects at two axial locations. In addition, annular pellets will be used at the top and bottom of the pellet stack to allow thermocouples within the rod to measure the fuel centerline temperature. Simulation results will be presented to illustrate the expected PCMI behavior and support the chosen experimental design parameters.

  17. Accurate Prediction of Glucuronidation of Structurally Diverse Phenolics by Human UGT1A9 Using Combined Experimental and In Silico Approaches

    PubMed Central

    Wu, Baojian; Wang, Xiaoqiang; Zhang, Shuxing; Hu, Ming

    2012-01-01

    Purpose The catalytic selectivity of human UGT1A9, an important membrane-bound enzyme catalyzing glucuronidation of xenobiotics were determined experimentally using 145 phenolics, and analyzed by 3D-QSAR methods. Methods The catalytic efficiency of UGT1A9 was determined by kinetic profiling. Quantitative structure activity relationships were analyzed using the CoMFA and CoMSIA techniques. Molecular alignment of the substrate structures was made by superimposing the glucuronidation site and its adjacent aromatic ring to achieve maximal steric overlap. For a substrate with multiple active glucuronidation sites, each site was considered as a separate substrate. Results The 3D-QSAR analyses produced statistically reliable models with good predictive power (CoMFA: q2 = 0.548, r2= 0.949, r2pred = 0.775; CoMSIA: q2 = 0.579, r2= 0.876, r2pred = 0.700). The contour coefficient maps were applied to elucidate structural features among substrates that are responsible for the selectivity differences. Furthermore, the contour coefficient maps were overlaid in the catalytic pocket of a homology model of UGT1A9; this enabled us to identify the UGT1A9 catalytic pocket with a high degree of confidence. Conclusion The CoMFA/CoMSIA models can predict the substrate selectivity and in vitro clearance of UGT1A9. Our findings also provide a possible molecular basis for understanding UGT1A9 functions and its substrate selectivity. PMID:22302521

  18. Accurate determination of pair potentials for a C{sub w}H{sub x}N{sub y}O{sub z} system of molecules: A semiempirical method

    SciTech Connect

    Thiel, M. van; Ree, F.H.; Haselman, L.C.

    1995-03-01

    Statistical mechanical chemical equilibrium calculations of the properties of high-pressure high-temperature reactive C,H,N,O mixtures are made to derive an accurate self-consistent set of inter-molecular potentials for the product molecules. Previous theoretical efforts to predict such properties relied in part on Corresponding States theory and shock wave data of argon. More recent high-pressure Hugoniot measurements on a number of elements and molecules allow more accurate determination of the potentials of these materials, and explicit inclusion of additional dissociation products. The present discussion briefly reviews the previous analysis and the method used to produce a self-consistent set of potentials from shock data on N{sub 2}, O{sub 2}, H{sub 2}, NO, an N{sub 2} + O{sub 2} mixture, carbon, CO{sub 2}, and CO, as well as some simple explosive product mixtures from detonation of hexanitrobenzene, PETN, and a mixture of hydrazine nitrate, hydrazine and water. The results are tested using the data from an HMX explosive formulations. The effect of the non-equilibrium nature of carbon clusters is estimated using data for TNT as a standard to determine a nonequilibrium equation of state for carbon. The resulting parameter set is used in a survey of 27 explosives. For the subset that contains no fluorine or two-phase carbon effects the rms deviation from experimental detonation velocity is 1.2%.

  19. Experimental determination of the radius of curvature of an isotropic Gaussian Schell-model beam.

    PubMed

    Zhu, Shijun; Chen, Yahong; Cai, Yangjian

    2013-02-01

    We propose a method to determine the radius of curvature of an isotropic Gaussian Schell-model (GSM) beam by measuring the transverse beam widths and the transverse coherence widths at two different planes. Furthermore, we carry out experimental determination of the radius of curvature of a GSM beam. Using the measured beam parameters, we carry out a comparative study of the propagation properties of a GSM beam both theoretically and experimentally. Our experimental results agree well with theoretical predictions.

  20. Streptococcus pneumoniae capsule determines disease severity in experimental pneumococcal meningitis

    PubMed Central

    Grandgirard, Denis; Valente, Luca G.; Täuber, Martin G.; Leib, Stephen L.

    2016-01-01

    Streptococcus pneumoniae bacteria can be characterized into over 90 serotypes according to the composition of their polysaccharide capsules. Some serotypes are common in nasopharyngeal carriage whereas others are associated with invasive disease, but when carriage serotypes do invade disease is often particularly severe. It is unknown whether disease severity is due directly to the capsule type or to other virulence factors. Here, we used a clinical pneumococcal isolate and its capsule-switch mutants to determine the effect of capsule, in isolation from the genetic background, on severity of meningitis in an infant rat model. We found that possession of a capsule was essential for causing meningitis. Serotype 6B caused significantly more mortality than 7F and this correlated with increased capsule thickness in the cerebrospinal fluid (CSF), a stronger inflammatory cytokine response in the CSF and ultimately more cortical brain damage. We conclude that capsule type has a direct effect on meningitis severity. This is an important consideration in the current era of vaccination targeting a subset of capsule types that causes serotype replacement. PMID:27009189

  1. Experimental determination of gap scaling in a plasma opening switch

    NASA Astrophysics Data System (ADS)

    Black, D. C.; Commisso, R. J.; Ottinger, P. F.; Swanekamp, S. B.; Weber, B. V.

    2000-09-01

    Experiments were performed to investigate the coupling between a ˜0.5 μs conduction-time, ˜0.5 MA conduction-current plasma opening switch (POS), and an electron-beam (e-beam) diode. Electrical diagnostics provided measurements of the voltage at the oil-vacuum insulator and at the diode as well as anode and cathode currents on the generator and load sides of the POS. These measurements were combined with a flow impedance model to determine the POS gap over a range of conduction times and e-beam diode impedances, and for two POS-to-load distances. A comparison of the inferred POS gap at peak power with the critical gap for magnetic insulation indicates that the POS gap is always saturated in both switch-limited and load-limited regimes. This POS gap-size scaling with load impedance is consistent with an opening mechanism dominated by erosion and not J×B forces.

  2. Accurate determination of the reaction course in HY2 <−> Y + YH (Y = O, S): detailed analysis of the covalent- to hydrogen-bonding transition.

    PubMed

    Varandas, A J C

    2013-08-15

    The accurate prediction of a bond-breaking/bond-forming reaction course is useful but very difficult. Toward this goal, a cost-effective multireference scheme (A. J. C. Varandas, J. Chem. Theory Comput. 2012, 8, 428) is tested that provides a generalization of the Hartree-Fock plus dispersion model for closed-shell interactions, and hence is based on the popular but largely untested idea of performing single point calculations with a high-level method at stationary points or along paths located using a lower level method. The energetics so calculated for the reaction HO2 <−> O + OH is predicted in excellent agreement with the experimental data, whereas the reaction path shows a scar at the onset of hydrogen-bonding: a weak van der Waals type minimum separated from the deep covalent well by a small barrier, all below the O + OH asymptote. The O-OH long-range interaction potential is also examined and possible implications in reaction dynamics discussed. Corresponding attributes for the reaction HS2 <−> S + SH are predicted, in good agreement with the best theoretical and experimental results. A perspective on the general utility of the approach is presented.

  3. Rapid and Accurate Determination of Lipopolysaccharide O-Antigen Types in Klebsiella pneumoniae with a Novel PCR-Based O-Genotyping Method

    PubMed Central

    Shih, Yun-Jui; Cheong, Cheng-Man; Yi, Wen-Ching

    2015-01-01

    Klebsiella pneumoniae, a Gram-negative bacillus that causes life-threatening infections in both hospitalized patients and ambulatory persons, can be classified into nine lipopolysaccharide (LPS) O-antigen serotypes. The O-antigen type has important clinical and epidemiological significance. However, K. pneumoniae O serotyping is cumbersome, and the reagents are not commercially available. To overcome the limitations of conventional serotyping methods, we aimed to create a rapid and accurate PCR method for K. pneumoniae O genotyping. We sequenced the genetic determinants of LPS O antigen from serotypes O1, O2a, O2ac, O3, O4, O5, O8, O9, and O12. We established a two-step genotyping scheme, based on the two genomic regions associated with O-antigen biosynthesis. The first set of PCR primers, which detects alleles at the wzm-wzt loci of the wb gene cluster, distinguishes between O1/O2, O3, O4, O5, O8, O9, and O12. The second set of PCR primers, which detects alleles at the wbbY region, further differentiates between O1, O2a, and O2ac. We verified the specificity of O genotyping against the O-serotype reference strains. We then tested the sensitivity and specificity of O genotyping in K. pneumoniae, using the 56 K-serotype reference strains with known O serotypes determined by an inhibition enzyme-linked immunosorbent assay (iELISA). There is a very good correlation between the O genotypes and classical O serotypes. Three discrepancies were observed and resolved by nucleotide sequencing—all in favor of O genotyping. The PCR-based O genotyping, which can be easily performed in clinical and research microbiology laboratories, is a rapid and accurate method for determining the LPS O-antigen types of K. pneumoniae isolates. PMID:26719438

  4. Need for accurate and standardized determination of amino acids and bioactive peptides for evaluating protein quality and potential health effects of foods and dietary supplements.

    PubMed

    Gilani, G Sarwar; Xiao, Chaowu; Lee, Nora

    2008-01-01

    Accurate standardized methods for the determination of amino acid in foods are required to assess the nutritional safety and compositional adequacy of sole source foods such as infant formulas and enteral nutritionals, and protein and amino acid supplements and their hydrolysates, and to assess protein claims of foods. Protein digestibility-corrected amino acid score (PDCAAS), which requires information on amino acid composition, is the official method for assessing protein claims of foods and supplements sold in the United States. PDCAAS has also been adopted internationally as the most suitable method for routine evaluation of protein quality of foods by the Food and Agriculture Organization/World Health Organization. Standardized methods for analysis of amino acids by ion-exchange chromatography have been developed. However, there is a need to develop validated methods of amino acid analysis in foods using liquid chromatographic techniques, which have replaced ion-exchange methods for quantifying amino acids in most laboratories. Bioactive peptides from animal and plant proteins have been found to potentially impact human health. A wide range of physiological effects, including blood pressure-lowering effects, cholesterol-lowering ability, antithrombotic effects, enhancement of mineral absorption, and immunomodulatory effects have been described for bioactive peptides. There is considerable commercial interest in developing functional foods containing bioactive peptides. There is also a need to develop accurate standardized methods for the characterization (amino acid sequencing) and quantification of bioactive peptides and to carry out dose-response studies in animal models and clinical trials to assess safety, potential allergenicity, potential intolerance, and efficacy of bioactive peptides. Information from these studies is needed for determining the upper safe levels of bioactive peptides and as the basis for developing potential health claims for bioactive

  5. Preliminary analysis of problem of determining experimental performance of air-cooled turbine III : methods for determining power and efficiency

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Herman H , Jr; Ziemer, Robert R

    1950-01-01

    Suggested formula are given for determining air-cooled turbine-performance characteristics, such as power and efficiency, as functions of certain parameters. These functions, generally being unknown, are determined from experimental data obtained from specific investigations. Special plotting methods for isolating the effect of each parameter are outlined.

  6. A fast and accurate microwave-assisted digestion method for arsenic determination in complex mining residues by flame atomic absorption spectrometry.

    PubMed

    Pantuzzo, Fernando L; Silva, Julio César J; Ciminelli, Virginia S T

    2009-09-15

    A fast and accurate microwave-assisted digestion method for arsenic determination by flame atomic absorption spectrometry (FAAS) in typical, complex residues from gold mining is presented. Three digestion methods were evaluated: an open vessel digestion using a mixture of HCl:HNO(3):HF acids (Method A) and two microwave digestion methods using a mixture of HCl:H(2)O(2):HNO(3) in high (Method B) and medium-pressure (Method C) vessels. The matrix effect was also investigated. Arsenic concentration from external and standard addition calibration curves (at a 95% confidence level) were statistically equal (p-value=0.122) using microwave digestion in high-pressure vessel. The results from the open vessel digestion were statistically different (p-value=0.007) whereas in the microwave digestion in medium-pressure vessel (Method C) the dissolution of the samples was incomplete.

  7. Lipase-mediated enantioselective kinetic resolution of racemic acidic drugs in non-standard organic solvents: Direct chiral liquid chromatography monitoring and accurate determination of the enantiomeric excesses.

    PubMed

    Ghanem, Ashraf; Aboul-Enein, Mohammed Nabil; El-Azzouny, Aida; El-Behairy, Mohammed F

    2010-02-12

    The enantioselective resolution of a set of racemic acidic compounds such as non-steroidal anti-inflammatory drugs (NSAIDs) of the group arylpropionic acid derivatives is demonstrated. Thus, a set of lipases were screened and manipulated in either the esterification or hydrolysis mode for the enantioselective kinetic resolution of these racemates in non-standard organic solvents. The accurate determination of the enantiomeric excesses of both substrate and product during such reaction is demonstrated. This was based on the development of a direct and reliable enantioselective high performance liquid chromatography (HPLC) procedure for the simultaneous baseline separation of both substrate and product in one run without derivatization. This was achieved using the immobilized chiral stationary phase namely Chiralpak IB, a 3,5-dimethylphenylcarbamate derivative of cellulose (the immobilized version of Chiralcel OD) which proved to be versatile for the monitoring of the lipase-catalyzed kinetic resolution of racemates in non-standard organic solvents.

  8. TU-F-BRE-05: Experimental Determination of K Factor in Small Field Dosimetry

    SciTech Connect

    Das, I; Akino, Y; Francescon, P

    2014-06-15

    Purpose: Small-field dosimetry is challenging due to charged-particle disequilibrium, source occlusion and more importantly finite size of detectors. IAEA/AAPM has published approach to convert detector readings to dose by k factor. Manufacturers have been trying to provide various types of micro-detectors that could be used in small fields. However k factors depends on detector perturbations and are derived using Monte Carlo simulation. PTW has introduced a microDiamond for small-field dosimetry. An experimental approach is presented to derive the k factor for this detector. Methods: PTW microDiamond is a small volume detector with 1.1 mm radius and 1.0 micron thick synthetic diamond. Output factors were measured from 1×1cm2 to 12×12 cm2 on a Varian machine at various depths using various micro-detectors with published k factors. Dose is calculated as reading * K. Assuming k factor is accurate, output factor should be identical with every micro-detectors. Hence published k values (Francescon et al Med Phys 35, 504-513,2008) were used to covert readings and then output factors were computed. Based on the converged curve from other detectors, k factor for microDiamond was computed versus field size. Results: Traditional output factors as ratio of readings normalized to 10×10 cm2 differ significantly for micro-detectors for fields smaller than 3×3 cm2 which are now being used extensively. When readings are converted to dose, the output factor is independent of detector. Based on this method, k factor for microDiamond was estimated to be nearly constant 0.993±0.007 over varied field sizes. Conclusion: Our method provides a unique opportunity to determine the k factor for any unknown detector. It is shown that even though k factor depends on machine type due to focal spot, however for fields ≥1×1 cm2 this method provides accurate evaluation of k factor. Additionally microDiamond could be used with assumption that k factor is nearly unity.

  9. SU-E-T-250: Determining VMAT Machine Limitations of An Elekta Linear Accelerator with Agility MLC for Accurate Modeling in RayStation and Robust Delivery

    SciTech Connect

    Yang, K; Yu, Z; Chen, H; Mourtada, F

    2015-06-15

    Purpose: To implement VMAT in RayStation with the Elekta Synergy linac with the new Agility MLC, and to utilize the same vendor softwares to determine the optimum Elekta VMAT machine parameters in RayStation for accurate modeling and robust delivery. Methods: iCOMCat is utilized to create various beam patterns with user defined dose rate, gantry, MLC and jaw speed for each control point. The accuracy and stability of the output and beam profile are qualified for each isolated functional component of VMAT delivery using ion chamber and Profiler2 with isocentric mounting fixture. Service graphing on linac console is used to verify the mechanical motion accuracy. The determined optimum Elekta VMAT machine parameters were configured in RayStation v4.5.1. To evaluate the system overall performance, TG-119 test cases and nine retrospective VMAT patients were planned on RayStation, and validated using both ArcCHECK (with plug and ion chamber) and MapCHECK2. Results: Machine output and profile varies <0.3% when only variable is dose rate (35MU/min-600MU/min). <0.9% output and <0.3% profile variation are observed with additional gantry motion (0.53deg/s–5.8deg/s both directions). The output and profile variation are still <1% with additional slow leaf motion (<1.5cm/s both direction). However, the profile becomes less symmetric, and >1.5% output and 7% profile deviation is seen with >2.5cm/s leaf motion. All clinical cases achieved comparable plan quality as treated IMRT plans. The gamma passing rate is 99.5±0.5% on ArcCheck (<3% iso center dose deviation) and 99.1±0.8% on MapCheck2 using 3%/3mm gamma (10% lower threshold). Mechanical motion accuracy in all VMAT deliveries is <1°/1mm. Conclusion: Accurate RayStation modeling and robust VMAT delivery is achievable on Elekta Agility for <2.5cm/s leaf motion and full range of dose rate and gantry speed determined by the same vendor softwares. Our TG-119 and patient results have provided us with the confidence to use VMAT

  10. Accurate prediction of death by serial determination of galactose elimination capacity in primary biliary cirrhosis: a comparison with the Mayo model.

    PubMed

    Reichen, J; Widmer, T; Cotting, J

    1991-09-01

    We retrospectively analyzed the predictive accuracy of serial determinations of galactose elimination capacity in 61 patients with primary biliary cirrhosis. Death was predicted from the time that the regression line describing the decline in galactose elimination capacity vs. time intersected a value of 4 mg.min-1.kg-1. Thirty-one patients exhibited decreasing galactose elimination capacity; in 11 patients it remained stable and in 19 patients only one value was available. Among those patients with decreasing galactose elimination capacity, 10 died and three underwent liver transplantation; prediction of death was accurate to 7 +/- 19 mo. This criterion incorrectly predicted death in two patients with portal-vein thrombosis; otherwise, it did better than or as well as the Mayo clinic score. The latter was also tested on our patients and was found to adequately describe risk in yet another independent population of patients with primary biliary cirrhosis. Cox regression analysis selected only bilirubin and galactose elimination capacity, however, as independent predictors of death. We submit that serial determination of galactose elimination capacity in patients with primary biliary cirrhosis may be a useful adjunct to optimize the timing of liver transplantation and to evaluate new pharmacological treatment modalities of this disease.

  11. Accurate and self-consistent procedure for determining pH in seawater desalination brines and its manifestation in reverse osmosis modeling.

    PubMed

    Nir, Oded; Marvin, Esra; Lahav, Ori

    2014-11-01

    Measuring and modeling pH in concentrated aqueous solutions in an accurate and consistent manner is of paramount importance to many R&D and industrial applications, including RO desalination. Nevertheless, unified definitions and standard procedures have yet to be developed for solutions with ionic strength higher than ∼0.7 M, while implementation of conventional pH determination approaches may lead to significant errors. In this work a systematic yet simple methodology for measuring pH in concentrated solutions (dominated by Na(+)/Cl(-)) was developed and evaluated, with the aim of achieving consistency with the Pitzer ion-interaction approach. Results indicate that the addition of 0.75 M of NaCl to NIST buffers, followed by assigning a new standard pH (calculated based on the Pitzer approach), enabled reducing measured errors to below 0.03 pH units in seawater RO brines (ionic strength up to 2 M). To facilitate its use, the method was developed to be both conceptually and practically analogous to the conventional pH measurement procedure. The method was used to measure the pH of seawater RO retentates obtained at varying recovery ratios. The results matched better the pH values predicted by an accurate RO transport model. Calibrating the model by the measured pH values enabled better boron transport prediction. A Donnan-induced phenomenon, affecting pH in both retentate and permeate streams, was identified and quantified.

  12. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

    SciTech Connect

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl with the bulk-supporting electrolytes, based on the Pitzer model. The model developed in this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.

  13. Improved microwave-assisted wet digestion procedures for accurate Se determination in fish and shellfish by flow injection-hydride generation-atomic absorption spectrometry.

    PubMed

    Lavilla, I; González-Costas, J M; Bendicho, C

    2007-05-22

    Accurate determination of Se in biological samples, especially fish and shellfish, by hydride generation techniques has generally proven troublesome owing to the presence of organoselenium that cannot readily converted into inorganic selenium under usual oxidising conditions. Further improvements in the oxidation procedures are needed so as to obtain accurate concentration values when this type of samples is analyzed. Microwave-assisted wet digestion (MAWD) procedures of seafood based on HNO3 or the mixture HNO3/H2O2 and further thermal reduction of the Se(VI) formed to Se(IV) were evaluated. These procedures were as follows: (I) without H2O2 and without heating to dryness; (II) without H2O2 and with heating to dryness; (III) with H2O2 and without heating to dryness; (IV) with H2O2 and with heating to dryness. In general, low recoveries of selenium are obtained for several marine species (e.g., crustaceans and cephalopods), which may be ascribed to the presence of Se forms mainly associated with nonpolar proteins and lipids. Post-digestion UV irradiation proved very efficient since not only complete organoselenium decomposition was achieved but also the final step required for prereduction of Se(VI) into Se(IV) (i.e. heating at 90 degrees C for 30 min in 6M HCl) could be avoided. With the MAWD/UV procedure, the use of strong oxidising agents (persuphate, etc.) or acids (e.g. perchloric acid) which are typically applied prior to Se determination by hydride generation techniques is overcome, and as a result, sample pre-treatment is significantly simplified. The method was successfully validated against CRM DOLT-2 (dogfish liver), CRM DORM-2 (dogfish muscle) and CRM TORT-2 (lobster hepatopancreas). Automated ultrasonic slurry sampling with electrothermal atomic absorption spectrometry was also applied for comparison. Total Se contents in ten seafood samples were established. Se levels ranged from 0.7 to 2.9 microg g(-1).

  14. The determination of phenolic profiles of Serbian unifloral honeys using ultra-high-performance liquid chromatography/high resolution accurate mass spectrometry.

    PubMed

    Kečkeš, Silvio; Gašić, Uroš; Veličković, Tanja Ćirković; Milojković-Opsenica, Dušanka; Natić, Maja; Tešić, Živoslav

    2013-05-01

    Polyphenolic profiles of 44 unifloral Serbian honeys were analyzed using ultra-high-performance liquid chromatography (UHPLC) coupled with hybrid mass spectrometer which combines the Linear Trap Quadrupole (LTQ) and OrbiTrap mass analyzer. Rapid UHPLC method was developed in combination with a high sensitivity accurate mass scan and a simultaneous data dependent scan. The honey samples were of different botanical origin: acacia (Robinia pseudoacacia), sunflower (Helianthus annuus), linden (Tilia cordata), basil (Ocimum basilicum), buckwheat (Fagopyrum esculentum), oilseed rape (Brassica napus), and goldenrod (Solidago virgaurea). The presence of 43 compounds, mainly flavonoids, was proven in all honey samples by their characteristic mass spectra and fragmentation pattern. Relatively high amounts of chrysin, pinocembrin and galangin were identified in all honey extracts. p-Coumaric acid was not detected in basil, buckwheat and goldenrod honey extracts. A larger amount of gallic acid (max value 1.45 mg/kg) was found in the sunflower honey, while a larger amount of apigenin (0.97 mg/kg) was determined in the buckwheat honey in comparison with other honeys. The samples were classified according to the botanical origin using pattern recognition technique, Principal Component Analysis (PCA). The LTQ OrbiTrap technique was proven to be reliable for the unambiguous detection of phenolic acids, their derivatives, and flavonoid aglycones based on their molecular masses and fragmentation pattern.

  15. A rapid and accurate method for determining protein content in dairy products based on asynchronous-injection alternating merging zone flow-injection spectrophotometry.

    PubMed

    Liang, Qin-Qin; Li, Yong-Sheng

    2013-12-01

    An accurate and rapid method and a system to determine protein content using asynchronous-injection alternating merging zone flow-injection spectrophotometry based on reaction between coomassie brilliant blue G250 (CBBG) and protein was established. Main merit of our approach is that it can avoid interferences of other nitric-compounds in samples, such as melamine and urea. Optimized conditions are as follows: Concentrations of CBBG, polyvinyl alcohol (PVA), NaCl and HCl are 150 mg/l, 30 mg/l, 0.1 mol/l and 1.0% (v/v), respectively; volumes of the sample and reagent are 150 μl and 30 μl, respectively; length of a reaction coil is 200 cm; total flow rate is 2.65 ml/min. The linear range of the method is 0.5-15 mg/l (BSA), its detection limit is 0.05 mg/l, relative standard deviation is less than 1.87% (n=11), and analytical speed is 60 samples per hour.

  16. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS

    PubMed Central

    2016-01-01

    A gas chromatography-mass spectrometry (GC-MS) method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX) cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ) of propofol was 25 ng/mL. The validated method exhibited good linearity (R2 = 0.9989) with accuracy and precision −5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes. PMID:27597928

  17. Accurate determination of Curium and Californium isotopic ratios by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 248Cm samples for transmutation studies

    SciTech Connect

    Gourgiotis, A.; Isnard, H.; Aubert, M.; Dupont, E.; AlMahamid, I.; Cassette, P.; Panebianco, S.; Letourneau, A.; Chartier, F.; Tian, G.; Rao, L.; Lukens, W.

    2011-02-01

    The French Atomic Energy Commission has carried out several experiments including the mini-INCA (INcineration of Actinides) project for the study of minor-actinide transmutation processes in high intensity thermal neutron fluxes, in view of proposing solutions to reduce the radiotoxicity of long-lived nuclear wastes. In this context, a Cm sample enriched in {sup 248}Cm ({approx}97 %) was irradiated in thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). This work describes a quadrupole ICP-MS (ICP-QMS) analytical procedure for precise and accurate isotopic composition determination of Cm before sample irradiation and of Cm and Cf after sample irradiation. The factors that affect the accuracy and reproducibility of isotopic ratio measurements by ICP-QMS, such as peak centre correction, detector dead time, mass bias, abundance sensitivity and hydrides formation, instrumental background, and memory blank were carefully evaluated and corrected. Uncertainties of the isotopic ratios, taking into account internal precision of isotope ratio measurements, peak tailing, and hydrides formations ranged from 0.3% to 1.3%. This uncertainties range is quite acceptable for the nuclear data to be used in transmutation studies.

  18. Experimental Determination of GPR Groundwave Sampling Depth as a Function of Data Acquisition Parameters

    NASA Astrophysics Data System (ADS)

    Crist, T. L.; Benda, A.; Grote, K. R.

    2010-12-01

    Accurate measurements of near-surface soil water content are important for many applications, including environmental remediation, precision agriculture, and climate modeling. Conventional methods of measuring soil water content are usually limited to point measurements or shallow remote sensing techniques, but several researchers have shown that Ground Penetrating Radar (GPR) groundwaves can be used to accurately measure the near-surface soil water content rapidly and with high resolution. Previous laboratory research and modeling studies have shown that the sampling depth of GPR groundwaves is frequency dependent, and some modeling studies indicated that the sampling depth also depends on antenna separation. Thus, multi-frequency groundwave data or data acquired at different antenna separations might be used to create a vertical soil water content profile. However, the experimental data currently available were generated using sharp interfaces in water content, where a very wet soil was directly adjacent to a very dry soil; in natural environments, the soil water content distribution typically changes more gradually with depth. The previous experimental and modeling data also use variable-offset surveys to estimate a single sampling depth, so the effect of antenna separation on sampling depth cannot be determined from these studies. This experiment investigates how the groundwave sampling depth varies as a function of frequency and antenna separation in a natural soil environment during an infiltration experiment. The study area was a 2.5 m by 4.5 plot with no significant topography. To monitor changes in water content with depth throughout the experiment, eight boreholes were dug along the perimeter of the study area, and Time Domain Reflectometry (TDR) probes were installed at 7.5 cm vertical intervals to a depth of 53 cm in each borehole. TDR data were acquired every 10 minutes throughout the experiment. GPR data were acquired over the initially dry plot area

  19. New Possibilities for the Accurate in Situ Determination of Chalcophile and Siderophile Trace Elements by Laser Ablation Collision and Reaction Cell ICP-MS

    NASA Astrophysics Data System (ADS)

    Mason, P. R.

    2004-05-01

    Our knowledge of how chalcophile and siderophile elements partition in minerals is limited, mainly due to the lack of suitable techniques for their accurate in situ determination. Host minerals (e.g. sulphides) are typically of small size (<30 μ m) and highly heterogeneous in composition, requiring analysis of high spatial resolution. Concentrations of chalcophile elements in silicates and oxides are low (sub μ gg-1) and thus challenging to measure. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), offering high sensitivity and good spatial resolution (10-100 μ m) is thus highly suited for this purpose. Unfortunately, the widespread use of this technique has been limited by enhanced problems specific to chalcophile and siderophile elements. These include inaccuracy due to the presence of spectral interferences, elemental fractionation during ablation/ionization and the lack of suitable calibration standards. Polyatomic spectral interferences, present either as a background component (e.g. O2+, ArAr+) or based around the recombination of matrix elements with argon (e.g. ArS+, ArNi+) hinder accurate analysis. These depend upon the relative concentrations of major matrix components and trace elements to be measured and are significant in many relevant minerals (e.g. sulphides). The use of a collision and reaction cells in ICP-MS is a new method for selective interference attenuation, significantly improving detection limits for elements such as Fe, S and Se by between 1 and 4 orders of magnitude. ArNi+ and ArCu+ interferences in sulphides can be attenuated by at least an order of magnitude leading to improved accuracy for the measurement of the Platinum Group elements Rh and Ru. Sulphur isotopes can be measured interference-free at m/z=32 and 34 by eliminating background O2+. These improvements open up new possibilities for the use of LA-ICP-MS in trace element and isotopic studies at the lowest concentration levels or where sample

  20. Determining the representative volume element size for three-dimensional microstructural material characterization. Part 2: Application to experimental data

    NASA Astrophysics Data System (ADS)

    Harris, William M.; Chiu, Wilson K. S.

    2015-05-01

    Improved microstructural imaging and characterization methods have recently opened the door for quantitative evaluation of microstructures of such functional materials as solid oxide fuel cell and battery electrodes and composite gas separation membranes. Accurate quantitative characterization of these structures relies on the concept of a representative volume element (RVE) to provide a sufficiently large sample to be statistically representative of the material. In Part 1 of this work, several models were described to determine the RVE size for several common microstructural properties: volume fraction, particle size, and network contiguity. In this work, extensive synchrotron X-ray nanotomography imaging of a multiphase composite gas separation membrane is used to provide an experimental comparison to the model predictions. Results suggest that the models provide a reasonable estimate of RVE size, and can serve as a starting point for researchers planning imaging and characterization experiments.

  1. Contact-free experimental determination of the static flexural spring constant of cantilever sensors using a microfluidic force tool

    PubMed Central

    Parkin, John D

    2016-01-01

    Summary Micro- and nanocantilevers are employed in atomic force microscopy (AFM) and in micro- and nanoelectromechanical systems (MEMS and NEMS) as sensing elements. They enable nanomechanical measurements, are essential for the characterization of nanomaterials, and form an integral part of many nanoscale devices. Despite the fact that numerous methods described in the literature can be applied to determine the static flexural spring constant of micro- and nanocantilever sensors, experimental techniques that do not require contact between the sensor and a surface at some point during the calibration process are still the exception rather than the rule. We describe a noncontact method using a microfluidic force tool that produces accurate forces and demonstrate that this, in combination with a thermal noise spectrum, can provide the static flexural spring constant for cantilever sensors of different geometric shapes over a wide range of spring constant values (≈0.8–160 N/m). PMID:27335740

  2. Experimental Methodology for Determining Turbomachinery Blade Damping Using Magnetic Bearing Excitation and Non-Contacting Optical Measurements

    NASA Technical Reports Server (NTRS)

    Provenza, Andrew J.; Duffy, Kirsten P.

    2010-01-01

    Experiments to determine the effects of turbomachinery fan blade damping concepts such as passively shunted piezoelectric materials on blade response are ongoing at the NASA Glenn Research Center. A vertical rotor is suspended and excited with active magnetic bearings (AMBs) usually in a vacuum chamber to eliminate aerodynamic forces. Electromagnetic rotor excitation is superimposed onto rotor PD-controlled support and can be fixed to either a stationary or rotating frame of reference. The rotor speed is controlled with an air turbine system. Blade vibrations are measured using optical probes as part of a Non-Contacting Stress Measurement System (NSMS). Damping is calculated from these measurements. It can be difficult to get accurate damping measurements using this experimental setup and some of the details of how to obtain quality results are seemingly nontrivial. The intent of this paper is to present those details.

  3. Experimental determination of rotational constants of low-lying vibrational levels in the 0g- pure long-range state of ultracold Cs2 molecule

    NASA Astrophysics Data System (ADS)

    Wu, Jizhou; Liu, Wenliang; Li, Yuqing; Ma, Jie; Xiao, Liantuan; Jia, Suotang

    2017-04-01

    We report an accurate experimental determination of rotational constants of the lowest vibrational levels in the purely long-range state of ultracold cesium molecules (Cs2). We engineer a precise reference of the frequency difference through double photoassociation spectroscopy (PAS). The PAS for the lowest vibrational levels, v=0-3, has been obtained with an enhanced sensitivity and accuracy, according to which the binding energies have been corrected. As deduced from the reference, the frequency intervals between neighboring rotational levels are fitted to a non-rigid rotor model, thus the rotational constants are precisely obtained. The experimental results show good agreement with theoretical expectations.

  4. Effect of experimental and sample factors on dehydration kinetics of mildronate dihydrate: mechanism of dehydration and determination of kinetic parameters.

    PubMed

    Bērziņš, Agris; Actiņš, Andris

    2014-06-01

    The dehydration kinetics of mildronate dihydrate [3-(1,1,1-trimethylhydrazin-1-ium-2-yl)propionate dihydrate] was analyzed in isothermal and nonisothermal modes. The particle size, sample preparation and storage, sample weight, nitrogen flow rate, relative humidity, and sample history were varied in order to evaluate the effect of these factors and to more accurately interpret the data obtained from such analysis. It was determined that comparable kinetic parameters can be obtained in both isothermal and nonisothermal mode. However, dehydration activation energy values obtained in nonisothermal mode showed variation with conversion degree because of different rate-limiting step energy at higher temperature. Moreover, carrying out experiments in this mode required consideration of additional experimental complications. Our study of the different sample and experimental factor effect revealed information about changes of the dehydration rate-limiting step energy, variable contribution from different rate limiting steps, as well as clarified the dehydration mechanism. Procedures for convenient and fast determination of dehydration kinetic parameters were offered.

  5. Experimentally determined stiffness and damping of an inherently compensated air squeeze-film damper

    NASA Technical Reports Server (NTRS)

    Cunningham, R. E.

    1975-01-01

    Values of damping and stiffness were determined experimentally for an externally pressurized, inherently compensated, compressible squeeze-film damper up to excitation frequencies of 36,000 cycles per minute. Experimental damping values were higher than theory predicted at low squeeze numbers and less than predicted at high squeeze numbers. Experimental values of air film stiffness were less than theory predicted at low squeeze numbers and much greater at higher squeeze numbers. Results also indicate sufficient damping to attenuate amplitudes and forces at the critical speed when using three dampers in the flexible support system of a small, lightweight turborotor.

  6. Experimental and analytical determination of stability parameters for a balloon tethered in a wind

    NASA Technical Reports Server (NTRS)

    Redd, L. T.; Bennett, R. M.; Bland, S. R.

    1973-01-01

    Experimental and analytical techniques for determining stability parameters for a balloon tethered in a steady wind are described. These techniques are applied to a particular 7.64-meter-long balloon, and the results are presented. The stability parameters of interest appear as coefficients in linearized stability equations and are derived from the various forces and moments acting on the balloon. In several cases the results from the experimental and analytical techniques are compared and suggestions are given as to which techniques are the most practical means of determining values for the stability parameters.

  7. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

    NASA Astrophysics Data System (ADS)

    Abadlia, L.; Gasser, F.; Khalouk, K.; Mayoufi, M.; Gasser, J. G.

    2014-09-01

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  8. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: application to pure copper, platinum, tungsten, and nickel at very high temperatures.

    PubMed

    Abadlia, L; Gasser, F; Khalouk, K; Mayoufi, M; Gasser, J G

    2014-09-01

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  9. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

    SciTech Connect

    Abadlia, L.; Mayoufi, M.; Gasser, F.; Khalouk, K.; Gasser, J. G.

    2014-09-15

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  10. Experimental determination of the particle motions associated with the low order acoustic modes in enclosures

    NASA Technical Reports Server (NTRS)

    Byrne, K. P.; Marshall, S. E.

    1983-01-01

    A procedure for experimentally determining, in terms of the particle motions, the shapes of the low order acoustic modes in enclosures is described. The procedure is based on finding differentiable functions which approximate the shape functions of the low order acoustic modes when these modes are defined in terms of the acoustic pressure. The differentiable approximating functions are formed from polynomials which are fitted by a least squares procedure to experimentally determined values which define the shapes of the low order acoustic modes in terms of the acoustic pressure. These experimentally determined values are found by a conventional technique in which the transfer functions, which relate the acoustic pressures at an array of points in the enclosure to the volume velocity of a fixed point source, are measured. The gradient of the function which approximates the shape of a particular mode in terms of the acoustic pressure is evaluated to give the mode shape in terms of the particle motion. The procedure was tested by using it to experimentally determine the shapes of the low order acoustic modes in a small rectangular enclosure.

  11. Use of the Contour Method to Determine Autofrettage Residual Stresses: A Proposed Experimental Procedure

    DTIC Science & Technology

    2013-05-01

    determination of residual stresses in a long section of swage -autofrettaged gun tube by employing the relatively new contour method (CM). The CM...stresses, swage -autofrettage, contour method (CM), electric discharge machining (EDM), gun tube, and cutting, 16. SECURITY CLASSIFICATION OF: 17...4 Experimental Evidence Relating to Swage Autofrettage

  12. 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…

  13. Experimental and Theoretical Determination of Heavy Oil Viscosity Under Reservoir Conditions

    SciTech Connect

    Gabitto, Jorge; Barrufet, Maria

    2002-03-11

    The main objective of this research was to propose a simple procedure to predict heavy oil viscosity at reservoir conditions as a function of easily determined physical properties. This procedure will avoid costly experimental testing and reduce uncertainty in designing thermal recovery processes.

  14. Comparison between experimental and computational methods for scattering anisotropy coefficient determination in dental-resin composites

    NASA Astrophysics Data System (ADS)

    Fernández-Oliveras, Alicia; Carrasco, Irene M.; Ghinea, Razvan; Pérez, María M.; Rubiño, Manuel

    2012-06-01

    Understanding the behaviour of light propagation in biological materials is essential for biomedical engineering and its applications. Among the key optical properties of biological media is the angular distribution of the scattered light, characterized by the average cosine of the scattering angle, called the scattering anisotropy coefficient (g). The value of g can be determined by experimentally irradiating the material with a laser beam and making angular-scattering measurements in a goniometer. In this work, an experimental technique was used to determine g by means of goniometric measurements of the laser light scattered off two different dental-resin composites (classified as nano and hybrid). To assess the accuracy of the experimental method, a Mie theory-based computational model was used. Independent measurements were used to determine some of the required input parameters for computation of the theoretical model. The g values estimated with the computational method (nano-filled: 0.9399; hybrid: 0.8975) and the values calculated with the experimental method presented (nano-filled: 0.98297 +/- 0.00021; hybrid: 0.95429 +/- 0.00014) agreed well for both dental resins, with slightly higher experimental values. The higher experimental values may indicate that the scattering particle causes more narrow-angle scattering than does a perfect sphere of equal volume, assuming that with more spherical scattering particles the scattering anisotropy coefficient increases. Since g represents the angular distribution of the scattered light, values provided by both the experimental and the computational methods show a strongly forward-directed scattering in the dental resins studied, more pronounced in the nano-filled composite than in the hybrid composite.

  15. Determination of moisture-dependent moisture diffusivity using smoothed experimental data

    NASA Astrophysics Data System (ADS)

    Kočí, Václav; Kočí, Jan; Ďurana, Kamil; Maděra, Jiří; Černý, Robert

    2013-10-01

    Application of large sets of experimental data containing measurement errors in computational analyses without any preprocessing can lead to distortion of results. Therefore, transformation of these data from point-wise given values to smooth curves is one of the key factors allowing their proper utilization. In this paper, determination of moisture diffusivity of autoclaved aerated concrete as a function of moisture content using measured moisture profiles, which are processed by smoothing, is presented. For the processing of experimentally measured data smoothing splines are used.

  16. Experimental determination of the solubility of iridium in silicate melts: Preliminary results

    NASA Technical Reports Server (NTRS)

    Borisov, Alexander; Dingwell, Donald B.; Oneill, Hugh ST.C.; Palme, Herbert

    1992-01-01

    Little is known of the geochemical behavior of iridium. Normally this element is taken to be chalcophile and/or siderophile so that during planetary differentiation processes, e.g., core formation, iridium is extracted from silicate phases into metallic phases. Experimental determination of the metal/silicate partition coefficient of iridium is difficult simply because it is so large. Also there are no data on the solubility behavior of iridium in silicate melts. With information on the solubility of iridium in silicate melts it is possible, in combination with experimental data for Fe-Ir alloys, to calculate the partition coefficient between a metallic phase and a silicate melt.

  17. Accurate Size and Size-Distribution Determination of Polystyrene Latex Nanoparticles in Aqueous Medium Using Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation with Multi-Angle Light Scattering

    PubMed Central

    Kato, Haruhisa; Nakamura, Ayako; Takahashi, Kayori; Kinugasa, Shinichi

    2012-01-01

    Accurate determination of the intensity-average diameter of polystyrene latex (PS-latex) by dynamic light scattering (DLS) was carried out through extrapolation of both the concentration of PS-latex and the observed scattering angle. Intensity-average diameter and size distribution were reliably determined by asymmetric flow field flow fractionation (AFFFF) using multi-angle light scattering (MALS) with consideration of band broadening in AFFFF separation. The intensity-average diameter determined by DLS and AFFFF-MALS agreed well within the estimated uncertainties, although the size distribution of PS-latex determined by DLS was less reliable in comparison with that determined by AFFFF-MALS.

  18. Structure elucidation of degradation products of the antibiotic amoxicillin with ion trap MS(n) and accurate mass determination by ESI TOF.

    PubMed

    Nägele, Edgar; Moritz, Ralf

    2005-10-01

    Today, it is necessary to identify relevant compounds appearing in discovery and development of new drug substances in the pharmaceutical industry. For that purpose, the measurement of accurate molecular mass and empirical formula calculation is very important for structure elucidation in addition to other available analytical methods. In this work, the identification and confirmation of degradation products in a finished dosage form of the antibiotic drug amoxicillin obtained under stress conditions will be demonstrated. Structure elucidation is performed utilizing liquid chromatography (LC) ion trap MS/MS and MS3 together with accurate mass measurement of the molecular ions and of the collision induced dissociation (CID) fragments by liquid chromatography electro spray ionization time-of-flight mass spectrometry (LC/ESI-TOF).

  19. Experimental determination of micromachined discrete and continuous device spring constants using nanoindentation method

    NASA Astrophysics Data System (ADS)

    Chan, M. L.; Tay, Francis E.; Logeeswaran, V. J.; Zeng, Kaiyang; Shen, Lu; Chau, Fook S.

    2002-04-01

    A rapid and accurate static and quasi-static method for determining the out-of-plane spring constraints of cantilevers and a micromachined vibratory sensor is presented. In the past, much of the effort in nanoindentation application was to investigate the thin-film mechanical properties. In this paper, we have utilized the nanoindentation method to measure directly some micromachined device (e.g. microgyroscope) spring constants. The cantilevers and devices tested were fabricated using the MUMPS process and an SOI process (patent pending). Spring constants are determined using a commercial nanoindentation apparatus UMIS-2000 configured with both Berkovich and spherical indenter tip that can be placed onto the device with high accuracy. Typical load resolution is 20micrometers N to 0.5N and a displacement resolution of 0.05nm. Information was deduced from the penetration depth versus load curves during both loading and unloading.

  20. Experimental design methodologies to optimise the spectrofluorimetric determination of Losartan and Valsartan in human urine.

    PubMed

    Cagigal, E; González, L; Alonso, R M; Jiménez, R M

    2001-07-06

    A spectrofluorimetric method has been developed for the determination of two angiotensin II receptor antagonists (ARA II): Losartan and Valsartan. A fractional factorial design and a central composite design were used. The key factors considered in the optimization process were pH, temperature and emission slit width. Maximum fluorescent intensity was established as response for each experiment. The response surfaces confirmed the robustness of the method. A clean-up procedure was used for urine samples that consisted of a solid-phase extraction using C8 cartridges. The total analysis time was lower than 30 min. This method proved to be accurate (RE, 8%), precise (intra- and inter-day coefficients of variation were lower than 8% and sensitive enough (LOQ c.a. 0.5 mug ml(-1)) to be applied to the determination of Losartan and Valsartan in urine samples.

  1. XModeScore: a novel method for accurate protonation/tautomer-state determination using quantum-mechanically driven macromolecular X-ray crystallographic refinement

    PubMed Central

    Borbulevych, Oleg; Martin, Roger I.; Tickle, Ian J.; Westerhoff, Lance M.

    2016-01-01

    Gaining an understanding of the protein–ligand complex structure along with the proper protonation and explicit solvent effects can be important in obtaining meaningful results in structure-guided drug discovery and structure-based drug discovery. Unfortunately, protonation and tautomerism are difficult to establish with conventional methods because of difficulties in the experimental detection of H atoms owing to the well known limitations of X-ray crystallography. In the present work, it is demonstrated that semiempirical, quantum-mechanics-based macromolecular crystallographic refinement is sensitive to the choice of a protonation-state/tautomer form of ligands and residues, and can therefore be used to explore potential states. A novel scoring method, called XModeScore, is described which enumerates the possible protomeric/tautomeric modes, refines each mode against X-ray diffraction data with the semiempirical quantum-mechanics (PM6) Hamiltonian and scores each mode using a combination of energetic strain (or ligand strain) and rigorous statistical analysis of the difference electron-density distribution. It is shown that using XModeScore it is possible to consistently distinguish the correct bound protomeric/tautomeric modes based on routine X-ray data, even at lower resolutions of around 3 Å. These X-ray results are compared with the results obtained from much more expensive and laborious neutron diffraction studies for three different examples: tautomerism in the acetazolamide ligand of human carbonic anhydrase II (PDB entries 3hs4 and 4k0s), tautomerism in the 8HX ligand of urate oxidase (PDB entries 4n9s and 4n9m) and the protonation states of the catalytic aspartic acid found within the active site of an aspartic protease (PDB entry 2jjj). In each case, XModeScore applied to the X-ray diffraction data is able to determine the correct protonation state as defined by the neutron diffraction data. The impact of QM-based refinement versus conventional

  2. XModeScore: a novel method for accurate protonation/tautomer-state determination using quantum-mechanically driven macromolecular X-ray crystallographic refinement.

    PubMed

    Borbulevych, Oleg; Martin, Roger I; Tickle, Ian J; Westerhoff, Lance M

    2016-04-01

    Gaining an understanding of the protein-ligand complex structure along with the proper protonation and explicit solvent effects can be important in obtaining meaningful results in structure-guided drug discovery and structure-based drug discovery. Unfortunately, protonation and tautomerism are difficult to establish with conventional methods because of difficulties in the experimental detection of H atoms owing to the well known limitations of X-ray crystallography. In the present work, it is demonstrated that semiempirical, quantum-mechanics-based macromolecular crystallographic refinement is sensitive to the choice of a protonation-state/tautomer form of ligands and residues, and can therefore be used to explore potential states. A novel scoring method, called XModeScore, is described which enumerates the possible protomeric/tautomeric modes, refines each mode against X-ray diffraction data with the semiempirical quantum-mechanics (PM6) Hamiltonian and scores each mode using a combination of energetic strain (or ligand strain) and rigorous statistical analysis of the difference electron-density distribution. It is shown that using XModeScore it is possible to consistently distinguish the correct bound protomeric/tautomeric modes based on routine X-ray data, even at lower resolutions of around 3 Å. These X-ray results are compared with the results obtained from much more expensive and laborious neutron diffraction studies for three different examples: tautomerism in the acetazolamide ligand of human carbonic anhydrase II (PDB entries 3hs4 and 4k0s), tautomerism in the 8HX ligand of urate oxidase (PDB entries 4n9s and 4n9m) and the protonation states of the catalytic aspartic acid found within the active site of an aspartic protease (PDB entry 2jjj). In each case, XModeScore applied to the X-ray diffraction data is able to determine the correct protonation state as defined by the neutron diffraction data. The impact of QM-based refinement versus conventional

  3. Experimental level-structure determination in odd-odd actinide nuclei

    SciTech Connect

    Hoff, R.W.

    1985-04-04

    The status of experimental determination of level structure in odd-odd actinide nuclei is reviewed. A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei is applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation are derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings are used. Calculated and experimental level structures for /sup 238/Np, /sup 244/Am, and /sup 250/Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Applications of this modeling technique are discussed.

  4. Experimental method for determination of bending and torsional rigidities of advanced composite laminates

    SciTech Connect

    Maeda, Takenori

    1995-11-01

    This paper presents an experimental method for the determination of the bending and torsional rigidities of advanced fiber composite laminates with the aid of laser holographic interferometry. The proposed method consists of a four-point bending test and a resonance test. The bending rigidity ratio (D{sub 12}/D{sub 22}) can be determined from the fringe patterns of the four-point bending test. The bending rigidities (D{sub 11} and D{sub 22}) and the torsional rigidity (D{sub 66}) are calculated from the natural frequencies of cantilever plates of the resonance test. The test specimens are carbon/epoxy cross-ply laminates. The adequacy of the experimental method is confirmed by comparing the measured rigidities with the theoretical values obtained from classical lamination theory (CLT) by using the measured tensile properties. The results show that the present method can be used to evaluate the rigidities of orthotropic laminates with reasonably good accuracy.

  5. A proposed experimental method for interpreting Doppler effect measurements and determining their precision

    NASA Technical Reports Server (NTRS)

    Klann, P. G.

    1973-01-01

    The principal problem in the measurement of the Doppler reactivity effect is separating it from the thermal reactivity effects of the expansion of the heated sample. It is shown in this proposal that the thermal effects of sample expansion can be experimentally determined by making additional measurements with porous samples having the same mass and/or volume as the primary sample. By combining these results with independent measurements of the linear temperature coefficient and the computed temperature dependence of the Doppler coefficient the magnitude of the Doppler coefficient may be extracted from the data. These addiational measurements are also useful to experimentally determine the precision of the reactivity oscillator technique used to measure the reactivity effects of the heated sample.

  6. Experimental determination of multiple ionization cross sections in Si by electron impact

    NASA Astrophysics Data System (ADS)

    Pérez, Pablo Daniel; Sepúlveda, Andrés; Castellano, Gustavo; Trincavelli, Jorge

    2015-12-01

    The thin sample method is often used to experimentally determine ionization cross sections, especially when focusing on the low overvoltage region. The simplicity of the formalism involved in this method is very appealing, but some experimental complications arise in the preparation of thin films. In this work, a thick sample method was used to measure the Si-K x-ray production cross section by electron impact. The good agreement between the results obtained and the values reported in the literature validates the method and the parameters used. The advantages and disadvantages of the method are discussed and its application is extended to the determination of Si multiple-ionization cross sections, where the very low emission rates (around two orders of magnitude lower than the single-ionization case) make the use of the thin sample method impracticable.

  7. Semi-experimental equilibrium structure determinations by employing B3LYP/SNSD anharmonic force fields: validation and application to semirigid organic molecules.

    PubMed

    Piccardo, Matteo; Penocchio, Emanuele; Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo

    2015-03-12

    This work aims at extending the semi-experimental (SE) approach for deriving accurate equilibrium structures to large molecular systems of organic and biological interest. SE equilibrium structures are derived by a least-squares fit of the structural parameters to the experimental ground-state rotational constants of several isotopic species corrected by vibrational contributions computed by quantum mechanical (QM) methods. A systematic benchmark study on 21 small molecules (CCse set) is carried out to evaluate the performance of hybrid density functionals (in particular B3LYP) in the derivation of vibrational corrections to rotational constants. The resulting SE equilibrium structures show a very good agreement with the corresponding geometries obtained employing post-Hartree-Fock vibrational corrections. The use of B3LYP in conjunction with the double-ζ SNSD basis set strongly reduces the computational costs, thus allowing for the evaluation of accurate SE equilibrium structures for medium-sized molecular systems. On these grounds, an additional set of 26 SE equilibrium structures including the most common organic moieties has been set up by collecting the most accurate geometries available in the literature together with new determinations from the present work. The overall set of 47 SE equilibrium structures determined using B3LYP/SNSD vibrational corrections (B3se set) provides a high quality benchmark for validating the structural predictions of other experimental and/or computational approaches. Finally, we present a new strategy (referred to as the template approach) to deal with the cases for which it is not possible to fit all geometrical parameters due to the lack of experimental data.

  8. Experimental Measurement to Determine Fine Dry-Bulb and Wet-Bulb Thermocouple Response Times

    DTIC Science & Technology

    2004-12-20

    constants were calculated by first using Statistica software to find the range of time during which the change in temperature takes place. After the...temperature before and after the change for both the dry-bulb and the wet-bulb were determined, the data were graphed and the initial and final temperatures...bias, B, and experimental standard error of the mean, Sz, was determined from: URSS = [B2 + (t95S•)2Y1 (20) where t95 = Student t statistic for a

  9. Experimental Methodology for Determining Optimum Process Parameters for Production of Hydrous Metal Oxides by Internal Gelation

    SciTech Connect

    Collins, J.L.

    2005-10-28

    The objective of this report is to describe a simple but very useful experimental methodology that was used to determine optimum process parameters for preparing several hydrous metal-oxide gel spheres by the internal gelation process. The method is inexpensive and very effective in collection of key gel-forming data that are needed to prepare the hydrous metal-oxide microspheres of the best quality for a number of elements.

  10. Experimental determination of the effective point of measurement of cylindrical ionization chambers for high-energy photon and electron beams.

    PubMed

    Huang, Yanxiao; Willomitzer, Christian; Zakaria, Golam Abu; Hartmann, Guenther H

    2010-01-01

    Measurements of depth-dose curves in water phantom using a cylindrical ionization chamber require that its effective point of measurement is located at the measuring depth. Recommendations for the position of the effective point of measurement with respect to the central axis valid for high-energy electron and photon beams are given in dosimetry protocols. According to these protocols, the use of a constant shift P(eff) is currently recommended. However, this is still based on a very limited set of experimental results. It is therefore expected that an improved knowledge of the exact position of the effective point of measurement will further improve the accuracy of dosimetry. Recent publications have revealed that the position of the effective point of measurement is indeed varying with beam energy, field size and also with chamber geometry. The aim of this study is to investigate whether the shift of P(eff) can be taken to be constant and independent from the beam energy. An experimental determination of the effective point of measurement is presented based on a comparison between cylindrical chambers and a plane-parallel chamber using conventional dosimetry equipment. For electron beams, the determination is based on the comparison of halfvalue depth R(50) between the cylindrical chamber of interest and a well guarded plane-parallel Roos chamber. For photon beams, the depth of dose maximum, d(max), the depth of 80% dose, d(80), and the dose parameter PDD(10) were used. It was again found that the effective point of measurement for both, electron and photon beams Dosimetry, depends on the beam energy. The deviation from a constant value remains very small for photons, whereas significant deviations were found for electrons. It is therefore concluded that use of a single upstream shift value from the centre of the cylindrical chamber as recommended in current dosimetry protocols is adequate for photons, however inadequate for accurate electron beam dosimetry.

  11. A critical study on the experimental determination of stiffness and viscosity of the human triceps surae by free vibration methods.

    PubMed

    París-García, Federico; Barroso, Alberto; Cañas, José; Ribas, Juan; París, Federico

    2013-09-01

    Muscles and tendons play an important role in human performance. Their mechanical behaviour can be described by analytical/numerical models including springs and dampers. Free vibration techniques are a widely used approach to the in vivo determination of stiffness and viscosity of muscle-tendon complexes involved in sport movements. By considering the data reported in the literature, it appears that the visco-elastic properties of the triceps surae muscle-tendon complexes are independent of the modality in which free vibration is induced as well as they do not depend on the composition of the population of subjects submitted to the experiments. This research will critically discuss this important aspect focussing in particular on two studies documented in the literature. For this purpose, two equipments will be developed to reproduce literature experiments under the assumption that the oscillating part of the body behaves as a single-degree-of-freedom system: The governing degree of freedom is associated with the vertical displacement of the lower leg or with the rotation of the foot around the ankle articulation. Unlike literature, measurements are now conducted on the same population of subjects in order to draw more general conclusions on the real equivalence of results and validity of the mechanical properties determined experimentally. Free vibration tests are accurately simulated by analytical models describing the response of each vibrating system. It is found that if the two measurement protocols are applied to the same population of individuals as it is done in this study, values of visco-elastic properties of muscle-tendon complexes extracted from experimental data are significantly different, the differences presenting a convincing consistency. This result is in contrast with the literature and confirms the need to evaluate results of free vibration techniques by taking homogeneous bases of comparison.

  12. Experimental and numerical determination of temperature gradients for a single tube alkali metal thermal-to-electric converter cell

    NASA Technical Reports Server (NTRS)

    Wright, S.

    2001-01-01

    This paper presents the results from the experimental and numerical determination of shell temperature gradients for a single tube AMTEC cell evaluated under simulated deep space operating conditions.

  13. Determination of acid dissociation constants (pKa) of cephalosporin antibiotics: Computational and experimental approaches.

    PubMed

    Ribeiro, Alyson R; Schmidt, Torsten C

    2017-02-01

    Cefapirin (CEPA) and ceftiofur (CEF) are two examples of widely used veterinarian cephalosporins presenting multiple ionization centers. However, the acid dissociation constants (pKa) of CEF are missing and experimental data about CEPA are rare. The same is true for many cephalosporins, where available data are either incomplete or even wrong. Environmentally relevant biotic and abiotic processes depend primordially on the antibiotic pH-dependent speciation. Consequently, this physicochemical parameter should be reliable, including the correct ionization center identification. In this direction, two experimental techniques, potentiometry and spectrophotometry, along with two well-known pKa predictors, Marvin and ACD/Percepta, were used to study the macro dissociation constants of CEPA and CEF. Additionally, the experimental dissociation constants of 14 cephalosporins available in the literature were revised, compiled and compared with data obtained in silico. Only one value was determined experimentally for CEF (2.68 ± 0.05), which was associated to the carboxylic acid group deprotonation. For CEPA two values were obtained experimentally: 2.74 ± 0.01 for the carboxylic acid deprotonation and 5.13 ± 0.01 for the pyridinium ring deprotonation. In general, experimentally obtained values agree with the in silico predicted data (ACD/Percepta RMSE: 0.552 and Marvin RMSE: 0.706, n = 88). However, for cephalosporins having imine and aminothiazole groups structurally close, Marvin presented problems in pKa predictions. For the biological and environmental fate and effect discussion, it is important to recognize that CEPA and CEF, as well as many other cephalosporins, are present as anionic species in the biologic and environmentally relevant pH values of 6-7.5.

  14. Experimental determinations of the eigenmodes for composite bars made with carbon and Kevlar-carbon fibers

    NASA Astrophysics Data System (ADS)

    Miriţoiu, C. M.; Stănescu, M. M.; Burada, C. O.; Bolcu, D.; Roşca, V.

    2015-11-01

    For modal identification, the single-point excitation method has been widely used in modal tests and it consists in applying a force in a given point and recording the vibratory structure response in all interest points, including the excitation point. There will be presented the experimental recordings for the studied bars (with Kevlar-carbon or carbon fibers), the frequency response function in Cartesian and polar coordinates. By using the frequency response functions we determine the eigenparameters for each bar. We present the final panel of the eigenmodes (with the damping factors, eigenfrequencies and critical damping) for each considered bar. Using the eigenfrequency of the first determined eigenmode, the bars stiffness has been determined. The presented bars can be used in practical engineering for: car or bus body parts, planes body parts, bullet-proof vests, reinforcements for sandwich beams, and so on.

  15. Experimentally Determined Overall Heat Transfer Coefficients for Spacesuit Liquid Cooled Garments

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Rhodes, Richard; Anchondo, Ian; Westheimer, David; Campbell, Colin; Vogel, Matt; Vonaue, Walt; Conger, Bruce; Stein, James

    2015-01-01

    A Human-In-The-Loop (HITL) Portable Life Support System 2.0 (PLSS 2.0) test has been conducted at NASA Johnson Space Center in the PLSS Development Laboratory from October 27, 2014 to December 19, 2014. These closed-loop tests of the PLSS 2.0 system integrated with human subjects in the Mark III Suit at 3.7 psi to 4.3 psi above ambient pressure performing treadmill exercise at various metabolic rates from standing rest to 3000 BTU/hr (880 W). The bulk of the PLSS 2.0 was at ambient pressure but effluent water vapor from the Spacesuit Water Membrane Evaporator (SWME) and the Auxiliary Membrane Evaporator (Mini-ME), and effluent carbon dioxide from the Rapid Cycle Amine (RCA) were ported to vacuum to test performance of these components in flight-like conditions. One of the objectives of this test was to determine the overall heat transfer coefficient (UA) of the Liquid Cooling Garment (LCG). The UA, an important factor for modeling the heat rejection of an LCG, was determined in a variety of conditions by varying inlet water temperature, flow rate, and metabolic rate. Three LCG configurations were tested: the Extravehicular Mobility Unit (EMU) LCG, the Oceaneering Space Systems (OSS) LCG, and the OSS auxiliary LCG. Other factors influencing accurate UA determination, such as overall heat balance, LCG fit, and the skin temperature measurement, will also be discussed.

  16. Determination of competitive adsorption isotherms applying the nonlinear frequency response method. Part II. Experimental demonstration.

    PubMed

    Ilić, Milica; Petkovska, Menka; Seidel-Morgenstern, Andreas

    2009-08-14

    This paper demonstrates an experimental application of the nonlinear frequency response (FR) method extension to determine adsorption isotherms of binary mixtures. This method, based on the analysis of the response of a chromatographic column subjected to the sinusoidal inlet concentration changes, is shown to be an alternative for isotherm determination. The critical issue related to the successful application of the method is to reach experimentally the low frequency asymptotic behaviour of the corresponding frequency response functions (FRFs). Although, there are different possibilities to perform periodical inlet concentration changes, in this paper only simultaneous changes for both components were considered. The adsorption of phenol and 2-phenylethanol on octadecyl silica was analyzed experimentally using a mixture of methanol and water as a solvent. Parameters of competitive isotherms were also estimated for comparison using the classical perturbation method. Despite certain differences between competitive isotherms estimated with the two methods that were found, the obtained results show the potential of the nonlinear FR method for measuring competitive isotherms.

  17. EXPERIMENTAL AND THEORETICAL DETERMINATION OF HEAVY OIL VISCOSITY UNDER RESERVOIR CONDITIONS

    SciTech Connect

    Dr. Jorge Gabitto; Maria Barrufet

    2003-05-01

    The USA deposits of heavy oils and tar sands contain significant energy reserves. Thermal methods, particularly steam drive and steam soak, are used to recover heavy oils and bitumen. Thermal methods rely on several displacement mechanisms to recover oil, but the most important is the reduction of crude viscosity with increasing temperature. The main objective of this research is to propose a simple procedure to predict heavy oil viscosity at reservoir conditions as a function of easily determined physical properties. This procedure will avoid costly experimental testing and reduce uncertainty in designing thermal recovery processes. First, we reviewed critically the existing literature choosing the most promising models for viscosity determination. Then, we modified an existing viscosity correlation, based on the corresponding states principle in order to fit more than two thousand commercial viscosity data. We collected data for compositional and black oil samples (absence of compositional data). The data were screened for inconsistencies resulting from experimental error. A procedure based on the monotonic increase or decrease of key variables was implemented to carry out the screening process. The modified equation was used to calculate the viscosity of several oil samples where compositional data were available. Finally, a simple procedure was proposed to calculate black oil viscosity from common experimental information such as, boiling point, API gravity and molecular weight.

  18. Sexing the Sciuridae: a simple and accurate set of molecular methods to determine sex in tree squirrels, ground squirrels and marmots.

    PubMed

    Gorrell, Jamieson C; Boutin, Stan; Raveh, Shirley; Neuhaus, Peter; Côté, Steeve D; Coltman, David W

    2012-09-01

    We determined the sequence of the male-specific minor histocompatibility complex antigen (Smcy) from the Y chromosome of seven squirrel species (Sciuridae, Rodentia). Based on conserved regions inside the Smcy intron sequence, we designed PCR primers for sex determination in these species that can be co-amplified with nuclear loci as controls. PCR co-amplification yields two products for males and one for females that are easily visualized as bands by agarose gel electrophoresis. Our method provides simple and reliable sex determination across a wide range of squirrel species.

  19. Study on the applicability of a precise, accurate method for rapid evaluation of engine and lubricant performance. [determination of wear metal in used lubricating oils

    NASA Technical Reports Server (NTRS)

    Kinard, J. T.

    1975-01-01

    The development of a procedure for obtaining data related to wear metal determinations in used lubricants is discussed. The procedure makes it possible to obtain rapid, simultaneous determinations of a number of wear metals at levels of parts per thousand to low parts per billion using a small amount of sample. The electrode assembly and instrumentation used in the process are described. Samples of data obtained from tests conducted under controlled conditions are tabulated.

  20. Experimental determination of excitonic band structures of single-walled carbon nanotubes using circular dichroism spectra

    NASA Astrophysics Data System (ADS)

    Wei, Xiaojun; Tanaka, Takeshi; Yomogida, Yohei; Sato, Naomichi; Saito, Riichiro; Kataura, Hiromichi

    2016-10-01

    Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers. Our samples show higher circular dichroism intensities than the highest values reported in previous works, indicating their high enantiomeric purity. Excitonic band structure analysis is performed by assigning all observed Eii and Eij optical transitions in the circular dichroism spectra. The results reproduce the asymmetric structures of the valence and conduction bands predicted by density functional theory. Finally, we demonstrate that an extended empirical formula can estimate Eij optical transition energies for any (n,m) species.

  1. Clathrate Structure Determination by Combining Crystal Structure Prediction with Computational and Experimental (129) Xe NMR Spectroscopy.

    PubMed

    Selent, Marcin; Nyman, Jonas; Roukala, Juho; Ilczyszyn, Marek; Oilunkaniemi, Raija; Bygrave, Peter J; Laitinen, Risto; Jokisaari, Jukka; Day, Graeme M; Lantto, Perttu

    2017-01-23

    An approach is presented for the structure determination of clathrates using NMR spectroscopy of enclathrated xenon to select from a set of predicted crystal structures. Crystal structure prediction methods have been used to generate an ensemble of putative structures of o- and m-fluorophenol, whose previously unknown clathrate structures have been studied by (129) Xe NMR spectroscopy. The high sensitivity of the (129) Xe chemical shift tensor to the chemical environment and shape of the crystalline cavity makes it ideal as a probe for porous materials. The experimental powder NMR spectra can be used to directly confirm or reject hypothetical crystal structures generated by computational prediction, whose chemical shift tensors have been simulated using density functional theory. For each fluorophenol isomer one predicted crystal structure was found, whose measured and computed chemical shift tensors agree within experimental and computational error margins and these are thus proposed as the true fluorophenol xenon clathrate structures.

  2. Experimental determination of excitonic band structures of single-walled carbon nanotubes using circular dichroism spectra

    PubMed Central

    Wei, Xiaojun; Tanaka, Takeshi; Yomogida, Yohei; Sato, Naomichi; Saito, Riichiro; Kataura, Hiromichi

    2016-01-01

    Experimental band structure analyses of single-walled carbon nanotubes have not yet been reported, to the best of our knowledge, except for a limited number of reports using scanning tunnelling spectroscopy. Here we demonstrate the experimental determination of the excitonic band structures of single-chirality single-walled carbon nanotubes using their circular dichroism spectra. In this analysis, we use gel column chromatography combining overloading selective adsorption with stepwise elution to separate 12 different single-chirality enantiomers. Our samples show higher circular dichroism intensities than the highest values reported in previous works, indicating their high enantiomeric purity. Excitonic band structure analysis is performed by assigning all observed Eii and Eij optical transitions in the circular dichroism spectra. The results reproduce the asymmetric structures of the valence and conduction bands predicted by density functional theory. Finally, we demonstrate that an extended empirical formula can estimate Eij optical transition energies for any (n,m) species. PMID:27703139

  3. Optimized structure and thermochemical properties of flavonoids determined by the CHIH(medium) DFT model chemistry versus experimental techniques

    NASA Astrophysics Data System (ADS)

    Mendoza-Wilson, Ana María.; Lardizabal-Gutiérrez, Daniel; Torres-Moye, Enrique; Fuentes-Cobas, Luis; Balandrán-Quintana, René R.; Camacho-Dávila, Alejandro; Quintero-Ramos, Armando; Glossman-Mitnik, Daniel

    2007-12-01

    The purpose of this work was to evaluate the accuracy of the CHIH(medium)-DFT model chemistry (PBEg/CBSB2 ∗∗//PBEg/CBSB4) in the determination of the optimized structure and thermochemical properties of heterocyclic systems of medium size such as flavonoids, wherefore were selected three of the most abundant flavonoids in vegetable tissues, and which posses the higher antioxidant activity: quercetin, (+)-catechin and cyanidin. As reference systems were employed three cyclic compounds: phenol, catechol and resorcinol. The thermochemical properties evaluated were enthalpy of formation, bond dissociation enthalpy (BDE) and ionization potential (IP), following the scheme of isodesmic reactions. The theoretical results were compared with experimental data generated by X-ray diffraction and calorimetric techniques realized in part by us, whereas other data were taken from the literature. The results obtained in this work reveal that the CHIH(medium)-DFT model chemistry represents an accurate computational tool to calculate structural and thermochemical properties in the studied flavonoid and reference compounds. The average absolute deviation of enthalpy of formation for reference compounds was 3.0 kcal/mol, 2.64 kcal/mol for BDE, and 2.97 kcal/mol for IP.

  4. Determination of surface dose rate of indigenous (32)P patch brachytherapy source by experimental and Monte Carlo methods.

    PubMed

    Kumar, Sudhir; Srinivasan, P; Sharma, S D; Saxena, Sanjay Kumar; Bakshi, A K; Dash, Ashutosh; Babu, D A R; Sharma, D N

    2015-09-01

    Isotope production and Application Division of Bhabha Atomic Research Center developed (32)P patch sources for treatment of superficial tumors. Surface dose rate of a newly developed (32)P patch source of nominal diameter 25 mm was measured experimentally using standard extrapolation ionization chamber and Gafchromic EBT film. Monte Carlo model of the (32)P patch source along with the extrapolation chamber was also developed to estimate the surface dose rates from these sources. The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and radiochromic films are 82.03±4.18 (k=2) and 79.13±2.53 (k=2) respectively. The two values of the surface dose rates measured using the two independent experimental methods are in good agreement to each other within a variation of 3.5%. The surface dose rate to tissue (cGy/min) estimated using the MCNP Monte Carlo code works out to be 77.78±1.16 (k=2). The maximum deviation between the surface dose rates to tissue obtained by Monte Carlo and the extrapolation chamber method is 5.2% whereas the difference between the surface dose rates obtained by radiochromic film measurement and the Monte Carlo simulation is 1.7%. The three values of the surface dose rates of the (32)P patch source obtained by three independent methods are in good agreement to one another within the uncertainties associated with their measurements and calculation. This work has demonstrated that MCNP based electron transport simulations are accurate enough for determining the dosimetry parameters of the indigenously developed (32)P patch sources for contact brachytherapy applications.

  5. Experimental determination of field factors ([Formula: see text]) for small radiotherapy beams using the daisy chain correction method.

    PubMed

    Lárraga-Gutiérrez, José Manuel

    2015-08-07

    Recently, Alfonso et al proposed a new formalism for the dosimetry of small and non-standard fields. The proposed new formalism is strongly based on the calculation of detector-specific beam correction factors by Monte Carlo simulation methods, which accounts for the difference in the response of the detector between the small and the machine specific reference field. The correct calculation of the detector-specific beam correction factors demands an accurate knowledge of the linear accelerator, detector geometry and composition materials. The present work shows that the field factors in water may be determined experimentally using the daisy chain correction method down to a field size of 1 cm × 1 cm for a specific set of detectors. The detectors studied were: three mini-ionization chambers (PTW-31014, PTW-31006, IBA-CC01), three silicon-based diodes (PTW-60018, IBA-SFD and IBA-PFD) and one synthetic diamond detector (PTW-60019). Monte Carlo simulations and experimental measurements were performed for a 6 MV photon beam at 10 cm depth in water with a source-to-axis distance of 100 cm. The results show that the differences between the experimental and Monte Carlo calculated field factors are less than 0.5%-with the exception of the IBA-PFD-for field sizes between 1.5 cm × 1.5 cm and 5 cm × 5 cm. For the 1 cm × 1 cm field size, the differences are within 2%. By using the daisy chain correction method, it is possible to determine measured field factors in water. The results suggest that the daisy chain correction method is not suitable for measurements performed with the IBA-PFD detector. The latter is due to the presence of tungsten powder in the detector encapsulation material. The use of Monte Carlo calculated [Formula: see text] is encouraged for field sizes less than or equal to 1 cm × 1 cm for the dosimeters used in this work.

  6. On the determination of the crystal-vapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian

    NASA Astrophysics Data System (ADS)

    Modak, Viraj P.; Wyslouzil, Barbara E.; Singer, Sherwin J.

    2016-08-01

    The crystal-vapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into non-interacting sub-systems with crystal-vapor interfaces. We do this by turning off the interactions, ΔV, between the sub-systems. Using the soft-core scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy in terms of an average of e-βΔV in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a non-Gaussian theory for γ and find that the difference between the non-Gaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a Lennard-Jones crystal and are also tested for more complex molecular solids, the surface of octane and nonadecane. Alkane surfaces were chosen for study because their crystal-vapor surface free energy has been of particular interest for understanding surface freezing in these systems.

  7. On the determination of the crystal-vapor surface free energy, and why a Gaussian expression can be accurate for a system far from Gaussian.

    PubMed

    Modak, Viraj P; Wyslouzil, Barbara E; Singer, Sherwin J

    2016-08-07

    The crystal-vapor surface free energy γ is an important physical parameter governing physical processes, such as wetting and adhesion. We explore exact and approximate routes to calculate γ based on cleaving an intact crystal into non-interacting sub-systems with crystal-vapor interfaces. We do this by turning off the interactions, ΔV, between the sub-systems. Using the soft-core scheme for turning off ΔV, we find that the free energy varies smoothly with the coupling parameter λ, and a single thermodynamic integration yields the exact γ. We generate another exact method, and a cumulant expansion for γ by expressing the surface free energy in terms of an average of e(-βΔV) in the intact crystal. The second cumulant, or Gaussian approximation for γ is surprisingly accurate in most situations, even though we find that the underlying probability distribution for ΔV is clearly not Gaussian. We account for this fact by developing a non-Gaussian theory for γ and find that the difference between the non-Gaussian and Gaussian expressions for γ consist of terms that are negligible in many situations. Exact and approximate methods are applied to the (111) surface of a Lennard-Jones crystal and are also tested for more complex molecular solids, the surface of octane and nonadecane. Alkane surfaces were chosen for study because their crystal-vapor surface free energy has been of particular interest for understanding surface freezing in these systems.

  8. High-resolution photoelectron imaging of cold C{sub 60}{sup −} anions and accurate determination of the electron affinity of C{sub 60}

    SciTech Connect

    Huang, Dao-Ling; Dau, Phuong Diem; Liu, Hong-Tao; Wang, Lai-Sheng

    2014-06-14

    High-resolution photoelectron imaging and spectroscopy of cold C{sub 60}{sup −} anions are reported using a newly built photoelectron imaging apparatus coupled with an electrospray ionization source and a temperature-controlled cryogenic ion trap. Vibrationally resolved photoelectron spectra are obtained for the detachment transition from the ground state of C{sub 60}{sup −} to that of C{sub 60} at various detachment wavelengths from 354.84 nm to 461.35 nm. The electron affinity of C{sub 60} is accurately measured to be 2.6835 ± 0.0006 eV. Numerous unexpected vibrational excitations are observed in the photoelectron spectra due to the Jahn-Teller effect in C{sub 60}{sup −} and Hertzberg-Teller vibronic coupling in both C{sub 60}{sup −} and C{sub 60}. Both the relative intensities of vibrational peaks and their photoelectron angular distributions provide evidence for the vibronic couplings. The observed p-wave-like behavior in the angular distribution of the 0{sub 0}{sup 0} transition suggests that the electron is detached from an s-type orbital.

  9. Experimental determination of ablation vapor species from carbon phenolic heat-shield materials

    NASA Technical Reports Server (NTRS)

    Lincoln, K. A.

    1981-01-01

    The relative concentrations of vapors produced from carbon phenolic composites under thermal loadings approximating those expected at peak heating during vehicle entry into the atmospheres of the outer planets have been determined. The technique of vaporizing the surface of bulk samples by laser irradiation while measuring in situ the vapor species by mass spectrometry is described. Results show that vapor composition varies with irradiance level and with depth of heating (or extent of pyrolysis). Attempts are made to compare these experimental results with the theoretical predictions from computer codes.

  10. SHORT COMMUNICATION: Proposal for new experimental schemes to determine the Avogadro constant

    NASA Astrophysics Data System (ADS)

    Biraben, F.; Cadoret, M.; Cladé, P.; Genevès, G.; Gournay, P.; Guellati-Khélifa, S.; Julien, L.; Juncar, P.; de Mirandes, E.; Nez, F.

    2006-12-01

    We propose two experimental schemes for the determination of the Avogadro constant NA with a relative uncertainty of 10-7 or better combining a watt balance experiment and a cold atom experiment measuring h/m(X) (where h is the Planck constant and m(X) the mass of the atom X). We give some prospects about possible uncertainties, and we discuss the opportunity to test the existence of possible unknown correction factors for the Josephson effect and the quantum Hall effect.

  11. Method of experimental determination of the kinetic constants in fast polymerization reactions in nonisothermal diffusion conditions

    SciTech Connect

    Prochukhan, Yu.A.; Berlin, A.A.; Enikolopyan, N.S.

    1986-09-01

    A new method for the experimental determination of the kinetic constants k/sub p/ and k/sub t/ in fast polymerization reactions on the example of cationic (under the effect of AlCl/sub 3/, BF/sub 3/, and other catalysts) liquid phase polymerization of isobutylene in a flow was suggested. The study of the macrokinetic features of low-temperature polymerization of isobutylene revealed the specific conditions of the occurrence of the process (quasi-ideal displacement) which are characterized by the relative constancy and uniformity of the distribution of the concentrations of the reacting substances along the flow section.

  12. Joule heating effects and the experimental determination of temperature during CE.

    PubMed

    Evenhuis, Christopher J; Haddad, Paul R

    2009-03-01

    Joule heating is ubiquitous in electrokinetic separations. This review is in two major parts. The first part documents the effects of Joule heating on the physical properties of the electrolyte and efficiency of separations and the second part focuses on advances in the determination of electrolyte temperatures that have been described in the literature over the past 5 years. The focus is on methods that can be applied by practitioners without the need for elaborate experimental requirements. Although the emphasis is on CE, many of the conclusions also apply to microfluidic formats.

  13. Experimental determination of the spring constant of an individual multiwalled carbon nanotube cantilever using fluorescence measurement

    NASA Astrophysics Data System (ADS)

    Kwon, Soongeun; Park, Hyojun; Shim, Hyung Cheoul; Lee, Hyung Woo; Kwak, Yoon Keun; Kim, Soohyun

    2009-07-01

    We report an experimental method to determine the spring constant of a multiwalled carbon nanotube (MWNT) cantilever as a mechanical piconewton force transducer. Electrostatic actuation was employed to investigate the mechanical properties of a MWNT cantilever. In order to measure nanotube's deflection during actuation, fluorescent dyes were noncovalently attached to the end of the nanotubes. Also, the length dependence of the spring constant is studied by adjusting the length of MWNT via electrochemical etching. The results show that the spring constant of a MWNT cantilever is as small as 0.001 N/m and tunable in the range of 0.001-0.05 N/m.

  14. Highly precise experimental device for determining the heat capacity of liquids under pressure

    SciTech Connect

    Gonzalez-Salgado, D.; Valencia, J. L.; Troncoso, J.; Carballo, E.; Peleteiro, J.; Romani, L.; Bessieres, D.

    2007-05-15

    An experimental device for making isobaric heat capacity measurements of liquids under pressure is presented. The device is an adaptation of the Setaram micro-DSC II atmospheric-pressure microcalorimeter, including modifications of vessels and a pressure line allowing the pressure in the measurement system to be set, controlled, and stabilized. The high sensitivity of the apparatus combined with a suitable calibration procedure allows very accurate heat capacity measurements under pressure to be made. The relative uncertainty in the isobaric molar heat capacity measurements provided by the new device is estimated to be 0.08% at atmospheric pressure and 0.2% at higher levels. The device was validated from isobaric molar heat capacity measurements for hexane, nonane, decane, undecane, dodecane, and tridecane, all of which were highly consistent with reported data. It also possesses a high sensitivity as reflected in its response to changes in excess isobaric molar heat capacity with pressure, which were examined in this work for the first time by making heat capacity measurements throughout the composition range of the 1-hexanol+n-hexane system. Finally, preliminary measurements at several pressures near the critical conditions for the nitromethane+2-butanol binary system were made that testify to the usefulness of the proposed device for studying critical phenomena in liquids under pressure.

  15. Experimental studies for determining human discomfort response to vertical sinusoidal vibration

    NASA Technical Reports Server (NTRS)

    Dempsey, T. K.; Leatherwood, J. D.

    1975-01-01

    A study was conducted to investigate several problems related to methodology and design of experiments to obtain human comfort response to vertical sinusoidal vibration. Specifically, the studies were directed to the determination of (1) the adequacy of frequency averaging of vibration data to obtain discomfort predictors, (2) the effect of practice on subject ratings, (3) the effect of the demographic factors of age, sex, and weight, and (4) the relative importance of seat and floor vibrations in the determination of measurement and criteria specification location. Results indicate that accurate prediction of discomfort requires knowledge of both the acceleration level and frequency content of the vibration stimuli. More importantly, the prediction of discomfort was shown to be equally good based upon either floor accelerations or seat accelerations. Furthermore, it was demonstrated that the discomfort levels in different seats resulting from similar vibratory imputs were equal. Therefore, it was recommended that criteria specifications and acceleration measurements be made at the floor location. The results also indicated that practice did not systematically influence discomfort responses nor did the demographic factors of age, weight, and sex contribute to the discomfort response variation.

  16. Experimental Procedure Used To Determine The Flexural Rigidity For Composite Sandwich Bars With Various Thickness Values

    NASA Astrophysics Data System (ADS)

    Miriţoiu, Cosmin Mihai

    2015-09-01

    In this paper there is presented an experimental procedure used to determine the flexural rigidity for composite sandwich bars with polypropylene honeycomb core with various thickness values: 1, 1,5 and 2 cm. The composite bars will be reinforced with one layer of carbon fiber. The width value of the composite bars will be of 6 cm. In order to obtain the flexural rigidity the composite bars will be clamped at one end and left free at the other. An accelerometer will be placed at the free end used to record the free vibrations of these bars. The simplifying assumption of "bar" will be used in this research, so I have chosen several free lengths for the bars: 29, 32 and 35 cm. The eigenfrequency of the first eigenmode will be used to determine the flexural rigidity of the bars.

  17. First experimentally determined thermodynamic values of francium: hydration energy, energy of partitioning, and thermodynamic radius.

    PubMed

    Delmau, Lætitia H; Moine, Jérôme; Mirzadeh, Saed; Moyer, Bruce A

    2013-08-08

    The Gibbs energy of partitioning of Fr(+) ion between water and nitrobenzene has been determined to be 14.5 ± 0.6 kJ/mol at 25 °C, the first ever Gibbs energy of partitioning for francium in particular and the first ever solution thermodynamic quantity for francium in general. This value enabled the ionic radius and standard Gibbs energy of hydration for Fr(+) to be estimated as 173 pm and -251 kJ/mol, respectively, the former value being significantly smaller than previously thought. A new experimental method was established using a cesium dicarbollide as a cation-exchange agent, overcoming problems inherent to the trace-level concentrations of francium. The methodology opens the door to the study of the partitioning behavior of francium to other water-immiscible solvents and the determination of complexation constants for francium binding by receptor molecules.

  18. The experimental determination of atmospheric absorption from aircraft acoustic flight tests

    NASA Technical Reports Server (NTRS)

    Miller, R. L.; Oncley, P. B.

    1971-01-01

    A method for determining atmospheric absorption coefficients from acoustic flight test data is presented. Measurements from five series of acoustic flight tests were included in the study. The number of individual flights totaled 24: six Boeing 707 flights performed in May 1969 in connection with the turbofan nacelle modification program, eight flights from Boeing tests conducted during the same period, and 10 flights of the Boeing 747 airplane. The effects of errors in acoustic, meteorological, and aircraft performance and position measurements are discussed. Tabular data of the estimated sample variance of the data for each test are given for source directivity angles from 75 deg to 120 deg and each 1/3-octave frequency band. Graphic comparisons are made of absorption coefficients derived from ARP 866, using atmospheric profile data, with absorption coefficients determined by the experimental method described in the report.

  19. Experimental determination of the inertia constants of an airplane or of a missile

    NASA Technical Reports Server (NTRS)

    Loiseau, H.

    1983-01-01

    The possibility to measure the inertia constants of an airplane or of a missile by a unique experimental set up without having to materialize axes of rotation was investigated. It is sufficient to suspend the structure appropriately, to obtain the six natural modes determined by the suspension and to introduce these results as data into a computer. If the structure is very flexible it is necessary to take into account the first natural modes of deformation. Experiments on rigid and flexible models led to precise results and allow consideration of full scale measurements. The final goal is to provide, by a standard ground vibration test completed by the measured characteristics of the suspension modes, the set of data necessary for flutter calculations and for the determination of all the inertia constants.

  20. Experimental Determination of the H2O-undersaturated Peridotite Solidus

    NASA Astrophysics Data System (ADS)

    Sarafian, E. K.; Gaetani, G. A.; Hauri, E.; Sarafian, A.

    2015-12-01

    Knowledge of the H2O-undersaturated lherzolite solidus places important constraints on the process of melt generation beneath oceanic spreading centers. While it is generally accepted that the small concentration of H2O (~50-200 ug/g) dissolved in the oceanic upper mantle has a strong influence on the peridotite solidus, but this effect has not been directly determined through experiments. This is because (1) precisely controlling low concentrations of H2O in high-pressure melting experiments is thought to be difficult, (2) small amounts of melt are difficult to identify, and (3) the size of mineral grains that grow in near-solidus experiments is too small to be analyzed for H2O by either Fourier transform infrared (FTIR) spectroscopy or secondary ion mass spectrometry (SIMS). We have developed an experimental approach for determining the peridotite solidus as a function of H2O content that overcomes these difficulties. Our approach utilizes large (~300 um diameter) spheres of San Carlos olivine to monitor the concentration and behavior of H2O in our experiments.. The spheres are mixed in 5:95 proportions with a synthetic peridotite that has the composition of the depleted MORB mantle of Workman and Hart (2005). Partial melting experiments are conducted in is a piston cylinder device using pre-conditioned Au80Pd20 capsules. During an experiment, the H2O content of the San Carlos olivine spheres diffusively equilibrates with the peridotite matrix. After each experiment, the concentration of H2O dissolved in the olivine spheres is determined by secondary ion mass spectrometry. By analyzing the H2O content of the San Carlos olivine spheres and performing a simple mass balance, we can then calculate the amount of H2O in the capsule. The spheres also provides a means to determine the solidus temperature due to the strong partitioning of H2O into silicate melt compared to olivine, pyroxene, and spinel. When a small amount of melt is present the H2O partitions into the

  1. Applications of polarizable continuum models to determine accurate solution-phase thermochemical values across a broad range of cation charge - the case of U(III-VI).

    PubMed

    Parmar, Payal; Samuels, Alex; Clark, Aurora E

    2015-01-13

    Contributing factors to the solution-phase correction to the free energy of the molecular clusters U(H2O)n(3+/4+) and UO2(H2O)m(1+/2+) (n = 8, 9, 30, 41, 77; m = 4, 5, 30, 41, 77) have been examined as a function of cavity type in the integrated-equation-formalism-protocol (IEF) and SMD polarizable continuum models (PCMs). It is observed that the free energy correction, Gcorr, does not smoothly converge to zero as the number of explicitly solvating water molecules approaches the bulk limit, and the convergence behavior varies significantly with cavity and model. The rates of convergence of the gas-phase hydration energy, ΔGhyd, wherein the bare metal ion is inserted into a molecular water cluster and ΔGcorr for the reaction exhibit wide variations as a function of ion charge, cavity, and model. This is the likely source of previously reported discrepancies in predicted free energies of solvation for metal ions when using different PCM cavities and/or models. The cancellation of errors in ΔGhyd and ΔGcorr is optimal for clusters consisting of only a second solvation shell of explicit water molecules (n = m = 30). The UFF cavity within IEF, in particular, exhibits the most consistent cancellation of errors when using a molecular cluster consisting of a second shell of solvating water for all oxidation states of uranium, leading to accurate free energies of solvation ΔGsolv for these species.

  2. New Photometry and Spectra of AB Doradus C: An Accurate Mass Determination of a Young Low-Mass Object with Theoretical Evolutionary Tracks

    NASA Astrophysics Data System (ADS)

    Close, Laird M.; Thatte, Niranjan; Nielsen, Eric L.; Abuter, Roberto; Clarke, Fraser; Tecza, Matthias

    2007-08-01

    We present new photometric and spectroscopic measurements for the unique, young, low-mass evolutionary track calibrator AB Dor C. While the new Ks photometry is similar to that we have previously published, the spectral type is found to be much earlier. Based on new H and K IFS spectra of AB Dor C from Thatte et al. (Paper I), we adopt a spectral type of M5.5+/-1.0 for AB Dor C. This is considerably earlier than the M8+/-1 previously estimated by Close et al. and Nielsen et al. yet is consistent with the M6+/-1 independently derived by Luhman & Potter. However, the spectrum presented in Paper I and analyzed here is a significant improvement over any previous spectrum of AB Dor C. We also present new astrometry for the system, which further supports a 0.090+/-0.005 Msolar mass for the system. Once armed with an accurate spectrum and Ks flux, we find L=0.0021+/-0.0005 Lsolar and Teff=2925+170-145 K for AB Dor C. These values are consistent with a ~75 Myr, 0.090+/-0.005 Msolar object like AB Dor C according to the DUSTY evolutionary tracks. Hence, masses can be estimated from the H-R diagram with the DUSTY tracks for young low-mass objects such as AB Dor C. However, we cautiously note that underestimates of the mass from the tracks can occur if one lacks a proper (continuum-preserved) spectrum or is relying on near-infrared fluxes alone. Based on observations made with ESO telescopes at the Paranal Observatories under program 276.C-5013.

  3. Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination

    NASA Astrophysics Data System (ADS)

    Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

    2014-12-01

    A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 μm and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

  4. Experimental determination of dynamic characteristics of the VentrAssist implantable rotary blood pump.

    PubMed

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Qian, Yi

    2004-12-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump consists of a shaftless impeller, which also acts as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, which result from the small clearances between the outside surfaces of the impeller and the pump cavity. These small clearances range from approximately 50 microm to 230 microm in size in the version of pump reported here. This article presents experimental investigation into the dynamic characteristics of the impeller-bearing-pump housing system of the rotary blood pump for increasing pump speeds at different flow rates. The pump was mounted on a suspension system consisting of a platform and springs, where the natural frequency and damping ratio for the suspension system were determined. Real-time measurements of the impeller's displacement were performed using Hall effect sensors. A vertical disturbance force was exerted onto the pump housing, causing the impeller to be displaced in vertical direction from its dynamic equilibrium position within the pump cavity. The impeller displacement was represented by a decaying sine wave, which indicated the impeller restoring to its equilibrium position. From the decaying sine wave the natural frequency and stiffness coefficient of the system were determined. Furthermore, the logarithmic decrement method was used to determine the damping ratio and eventually the damping coefficient of the system. Results indicate that stiffness and damping coefficients increased as flow rate and pump speed increased, representing an increase in stability with these changing conditions. However, pump speed had a greater influence on the stiffness and damping coefficients than flow rate did, which was evident through dynamic analysis. Overall the experimental method presented in this

  5. Hydrodynamic Radii of Intrinsically Disordered Proteins Determined from Experimental Polyproline II Propensities.

    PubMed

    Tomasso, Maria E; Tarver, Micheal J; Devarajan, Deepa; Whitten, Steven T

    2016-01-01

    The properties of disordered proteins are thought to depend on intrinsic conformational propensities for polyproline II (PPII) structure. While intrinsic PPII propensities have been measured for the common biological amino acids in short peptides, the ability of these experimentally determined propensities to quantitatively reproduce structural behavior in intrinsically disordered proteins (IDPs) has not been established. Presented here are results from molecular simulations of disordered proteins showing that the hydrodynamic radius (Rh) can be predicted from experimental PPII propensities with good agreement, even when charge-based considerations are omitted. The simulations demonstrate that Rh and chain propensity for PPII structure are linked via a simple power-law scaling relationship, which was tested using the experimental Rh of 22 IDPs covering a wide range of peptide lengths, net charge, and sequence composition. Charge effects on Rh were found to be generally weak when compared to PPII effects on Rh. Results from this study indicate that the hydrodynamic dimensions of IDPs are evidence of considerable sequence-dependent backbone propensities for PPII structure that qualitatively, if not quantitatively, match conformational propensities measured in peptides.

  6. Accurate determination of ¹²⁹I concentrations and ¹²⁹I/¹³⁷Cs ratios in spent nuclear resins by Accelerator Mass Spectrometry.

    PubMed

    Nottoli, Emmanuelle; Bienvenu, Philippe; Labet, Alexandre; Bourlès, Didier; Arnold, Maurice; Bertaux, Maité

    2014-04-01

    Determining long-lived radionuclide concentrations in radioactive waste has fundamental implications for the long-term management of storage sites. This paper focuses on the measurement of low (129)I contents in ion exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). Iodine-129 concentrations were successfully determined using Accelerator Mass Spectrometry (AMS) following a chemical procedure which included (1) acid digestion of resin samples in HNO3/HClO4, (2) radioactive decontamination by selective iodine extraction using a new chromatographic resin (CL Resin), and (3) AgI precipitation. Measured (129)I concentrations ranged from 4 to 12 ng/g, i.e. from 0.03 to 0.08 Bq/g. The calculation of (129)I/(137)Cs activity ratios used for routine waste management produced values in agreement with the few available data for PWR resin samples.

  7. Application of a modified Haug and Lantzsch method for the rapid and accurate photometrical phytate determination in soybean, wheat, and maize meals.

    PubMed

    Reichwald, Kirsten; Hatzack, Frank

    2008-05-14

    A modified version of the Haug and Lantzsch method for rapid photometrical phytate determination was applied for the analysis of phytate in soybean, wheat, and maize meals. In comparison to the original protocol, the amount of the toxic reagent thioglycolic acid is reduced substantially to minimize potential health risks for laboratory personnel. Different extraction conditions for soybean meal were tested, and boiling for at least 30 min was found to be necessary to remove an interfering compound in soybean meal extracts. Phytate contents determined according to the modified Haug and Lantzsch method did not differ from those obtained by measuring total precipitated phosphorus or by sensitive and specific high-performance ion chromatography. Applicability and accuracy of the modified method for phytate analysis in major feed substrates, including soy-based textured vegetable protein, were demonstrated.

  8. Experimental determination of the critical Rayleigh number for thermomagnetic convection with focus on fluid composition

    NASA Astrophysics Data System (ADS)

    Heckert, M.; Sprenger, L.; Lange, A.; Odenbach, S.

    2015-05-01

    Thermomagnetic convection has been investigated for two kerosene-based magnetic fluids (EMG 905 and NF4000C) with a focus on the determination of the critical Rayleigh numbers for the onset of convective instability in a fluid layer. A comparison with published data for the ester-based APG 513A-fluid and theoretical predictions yield similar critical magnetic Rayleigh numbers for the EMG and APG-fluids around Ram,c ≈ 2500, which is near the expected value, but Ram,c = 856 for the NF-fluid. As the latter differs from the other two fluids mainly in the particle size distribution, it is assumed that the size of the particles has an important and yet uninvestigated impact on the convective behavior of magnetic fluids. • Comparison of the experimental results for differently composed magnetic fluids. • Determination of the critical magnetic Rayleigh number from the heat transport experiments for the different fluids. • Comparison of the critical magnetic Rayleigh number in dependence of the fluids' compositions with values coming from a former theory. • Fluid with a very narrow particle size distribution and a small mean particle size leads to an experimental critical magnetic Rayleigh number being roughly one third of the theoretically expected one.

  9. Determining the experimental leachability of copper, lead, and zinc in a harbor sediment and modeling.

    PubMed

    Chatain, Vincent; Blanc, Denise; Borschneck, Daniel; Delolme, Cécile

    2013-01-01

    The potential leaching of pollutants present in harbor sediments has to be evaluated in order to choose the best practices for managing them. Little is known about the speciation and mobility of heavy metals in these specific solid materials. The objective of this paper is to determine and model the leachability of copper, lead, and zinc present in harbor sediments in order to obtain essential new data. The mobility of inorganic contaminants in a polluted harbor sediment collected in France was investigated as a function of physicochemical conditions. The investigation relied mainly on the use of leaching tests performed in combination with mineralogical analysis and thermodynamic modeling using PHREEQC. The modeling phase was dedicated to both confirm the hypothesis formulated to explain the experimental results and improve the determination of the main physico-chemical parameters governing mobility. The experimental results and modeling showed that the release of copper, lead, and zinc is very low with deionized water which is due to the stability of the associated solid phases (organic matter, carbonate minerals, and/or iron sulfides) at natural slightly basic conditions. However, increased mobilization is observed under pH values below 6.0 and above 10.0. This methodology helped to consistently obtain the geochemical parameters governing the mobility of the contaminants studied.

  10. A hybrid numerical-experimental method for determination of dynamic fracture properties of material

    NASA Astrophysics Data System (ADS)

    Mihradi, S.; Putra, I. S.; Dirgantara, T.; Widagdo, D.; Truong, L. X.

    2010-03-01

    A novel hybrid numerical-experimental method to obtain dynamic fracture properties of materials has been developed in the present work. Specimens were tested with one-point bending configuration in the Hopkinson's bar apparatus, from which the impact loading profiles were measured. In this dynamic fracture experiment, the crack tip position was measured by two strips of special strain gage having five gages arranged in one strip. Since the strain gage record only gave strain signal of each gage as a function of time, a novel method is proposed to determine the time at which the crack tip passed each strain gage and the time when the crack finally stopped. From the data of crack tip position as a function of time, the crack speed then can be calculated. These data, i.e. the loading profile and the crack speed, were then used as the input of the Node-Based FEM program developed for dynamic fractures problems. With the proposed method, three dynamic fracture properties of materials i.e dynamic fracture toughness for crack initiation (KIcd), fracture toughness for crack propagation (KID), and crack arrest toughness (KIa) can simultaneously be obtained. The results obtained from the investigation of dynamic fracture properties of Polymethyl Methacrylate (PMMA) material by the present method are well compared with the ones in the literature and from the direct experimental measurement. The good agreement suggests that the hybrid method developed in the present work can be used reliably to determine the dynamic fracture properties of materials.

  11. A hybrid numerical-experimental method for determination of dynamic fracture properties of material

    NASA Astrophysics Data System (ADS)

    Mihradi, S.; Putra, I. S.; Dirgantara, T.; Widagdo, D.; Truong, L. X.

    2009-12-01

    A novel hybrid numerical-experimental method to obtain dynamic fracture properties of materials has been developed in the present work. Specimens were tested with one-point bending configuration in the Hopkinson's bar apparatus, from which the impact loading profiles were measured. In this dynamic fracture experiment, the crack tip position was measured by two strips of special strain gage having five gages arranged in one strip. Since the strain gage record only gave strain signal of each gage as a function of time, a novel method is proposed to determine the time at which the crack tip passed each strain gage and the time when the crack finally stopped. From the data of crack tip position as a function of time, the crack speed then can be calculated. These data, i.e. the loading profile and the crack speed, were then used as the input of the Node-Based FEM program developed for dynamic fractures problems. With the proposed method, three dynamic fracture properties of materials i.e dynamic fracture toughness for crack initiation (KIcd), fracture toughness for crack propagation (KID), and crack arrest toughness (KIa) can simultaneously be obtained. The results obtained from the investigation of dynamic fracture properties of Polymethyl Methacrylate (PMMA) material by the present method are well compared with the ones in the literature and from the direct experimental measurement. The good agreement suggests that the hybrid method developed in the present work can be used reliably to determine the dynamic fracture properties of materials.

  12. Bias determination for space accelerometers using the ZARM Catapult system - experimental setup and data analysis

    NASA Astrophysics Data System (ADS)

    Selig, Hanns; Santos Rodrigues, Manuel; Touboul, Pierre; Liorzou, Françoise

    2012-07-01

    Accelerometers for space applications - like the electrostatic differential accelrometer for the MICROSCOPE mission for testing the equivalence principle in space - have to be tested and qualified in μg-conditions in order to demonstrate the system operation and to determine the characteristic sensor parameters. One important characteristic property is the sensor bias. In principle one can determine the sensor bias directly by using the ZARM catapult system as test platform. Even in the evacuated drop tube the residual air pressure results in an air friction that depends on the capsule velocity. At the apex (highest point of the capsule trajectory) the acceleration (relative to the gravitational acceleration g) becomes zero due to the zero velocity at the apex. The direct measurement of the vertical linear acceleration sensor bias is affected by some additional effects that have to be understood in order to be able to determine the sensor bias. Two catapult campaigns have been carried out to demonstrate the principles of the bias determination using a SuperStar accelerometer (Onera). The presentation gives an overview on the experimental setup and on the corresponding data analysis.

  13. Experimental conditions for determination of the neutrino mass hierarchy with reactor antineutrinos

    NASA Astrophysics Data System (ADS)

    Pac, Myoung Youl

    2016-01-01

    This article reports the optimized experimental requirements to determine neutrino mass hierarchy using electron antineutrinos (νbare) generated in a nuclear reactor. The features of the neutrino mass hierarchy can be extracted from the | Δ m312 | and | Δ m322 | oscillations by applying the Fourier sine and cosine transforms to the L / E spectrum. To determine the neutrino mass hierarchy above 90% probability, the requirements on the energy resolution as a function of the baseline are studied at sin2 ⁡ 2θ13 = 0.1. If the energy resolution of the neutrino detector is less than 0.04 /√{Eν} and the determination probability obtained from Bayes' theorem is above 90%, the detector needs to be located around 48-53 km from the reactor(s) to measure the energy spectrum of νbare. These results will be helpful for setting up an experiment to determine the neutrino mass hierarchy, which is an important problem in neutrino physics.

  14. Experimental determination of the H2O-undersaturated peridotite solidus

    NASA Astrophysics Data System (ADS)

    Sarafian, E. K.; Gaetani, G. A.; Hauri, E. H.; Sarafian, A. R.

    2014-12-01

    Knowledge of the H2O-undersaturated lherzolite solidus places important constraints on the process of melt generation and mantle potential temperatures beneath oceanic spreading centers. The small concentration of H2O (~50-200 μg/g) dissolved in the oceanic mantle is thought to exert a strong influence on the peridotite solidus, but this effect has not been directly determined. The utility of existing experimental data is limited by a lack of information on the concentration of H2O dissolved in the peridotite and uncertainties involved with identifying small amounts of partial melt. We have developed an experimental approach for determining the peridotite solidus as a function of H2O content that overcomes these difficulties. Our initial results demonstrate that the solidus temperature for spinel lherzolite containing 150 μg/g H2O is higher than existing estimates for the anhydrous solidus. Our approach to determining the H2O-undersaturated lherzolite solidus is as follows. First, a small proportion (~5 %) of San Carlos olivine spheres, ~300 μm in diameter, are added to a peridotite synthesized from high-purity oxides and carbonates. Melting experiments are then conducted in pre-conditioned Au80Pd20 capsules over a range of temperatures at a single pressure using a piston-cylinder device. Water diffuses rapidly in olivine resulting in thorough equilibration between the olivine spheres and the surrounding fine-grained peridotite, and allowing the spheres to be used as hygrometers. After the experiment, the concentration of H2O dissolved in the olivine spheres is determined by secondary ion mass spectrometry. Melting experiments, spaced 20°C apart, were performed from 1250 to 1430°C at 1.5 GPa. The starting material has the composition of the depleted MORB mantle of Workman and Hart (2005) containing 0.13 wt% Na2O and 150 µg/g H2O. The concentration of H2O in the olivine spheres remains constant up to 1350°C, and then decreases systematically with increasing

  15. BIOACCESSIBILITY TESTS ACCURATELY ESTIMATE ...

    EPA Pesticide Factsheets

    Hazards of soil-borne Pb to wild birds may be more accurately quantified if the bioavailability of that Pb is known. To better understand the bioavailability of Pb to birds, we measured blood Pb concentrations in Japanese quail (Coturnix japonica) fed diets containing Pb-contaminated soils. Relative bioavailabilities were expressed by comparison with blood Pb concentrations in quail fed a Pb acetate reference diet. Diets containing soil from five Pb-contaminated Superfund sites had relative bioavailabilities from 33%-63%, with a mean of about 50%. Treatment of two of the soils with P significantly reduced the bioavailability of Pb. The bioaccessibility of the Pb in the test soils was then measured in six in vitro tests and regressed on bioavailability. They were: the “Relative Bioavailability Leaching Procedure” (RBALP) at pH 1.5, the same test conducted at pH 2.5, the “Ohio State University In vitro Gastrointestinal” method (OSU IVG), the “Urban Soil Bioaccessible Lead Test”, the modified “Physiologically Based Extraction Test” and the “Waterfowl Physiologically Based Extraction Test.” All regressions had positive slopes. Based on criteria of slope and coefficient of determination, the RBALP pH 2.5 and OSU IVG tests performed very well. Speciation by X-ray absorption spectroscopy demonstrated that, on average, most of the Pb in the sampled soils was sorbed to minerals (30%), bound to organic matter 24%, or present as Pb sulfate 18%. Ad

  16. Distribution of nuclear bomb Pu in Nishiyama area, Nagasaki, estimated by accurate and precise determination of 240Pu/239Pu ratio in soils.

    PubMed

    Yoshida, S; Muramatsu, Y; Yamazaki, S; Ban-Nai, T

    2007-01-01

    Plutonium isotopes in forest soils collected in Nishiyama area, Nagasaki, were successfully determined by high resolution inductively coupled plasma mass spectrometry after the treatment with a microwave decomposition system. The (240)Pu/(239)Pu atom ratios observed in the samples in the Nishiyama area were obviously lower than the range of the global fallout. The low ratios (minimum 0.032) observed in Nishiyama area indicated the influence of detonation of the Pu nuclear weapon in 1945. Since the area is contaminated also by global fallout, the (240)Pu/(239)Pu atom ratio can be more sensitive indicator of bomb-derived Pu than Pu activity concentration.

  17. Accurate ab initio determination of the adiabatic potential energy function and the Born-Oppenheimer breakdown corrections for the electronic ground state of LiH isotopologues

    NASA Astrophysics Data System (ADS)

    Holka, Filip; Szalay, Péter G.; Fremont, Julien; Rey, Michael; Peterson, Kirk A.; Tyuterev, Vladimir G.

    2011-03-01

    High level ab initio potential energy functions have been constructed for LiH in order to predict vibrational levels up to dissociation. After careful tests of the parameters of the calculation, the final adiabatic potential energy function has been composed from: (a) an ab initio nonrelativistic potential obtained at the multireference configuration interaction with singles and doubles level including a size-extensivity correction and quintuple-sextuple ζ extrapolations of the basis, (b) a mass-velocity-Darwin relativistic correction, and (c) a diagonal Born-Oppenheimer (BO) correction. Finally, nonadiabatic effects have also been considered by including a nonadiabatic correction to the kinetic energy operator of the nuclei. This correction is calculated from nonadiabatic matrix elements between the ground and excited electronic states. The calculated vibrational levels have been compared with those obtained from the experimental data [J. A. Coxon and C. S. Dickinson, J. Chem. Phys. 134, 9378 (2004)]. It was found that the calculated BO potential results in vibrational levels which have root mean square (rms) deviations of about 6-7 cm-1 for LiH and ˜3 cm-1 for LiD. With all the above mentioned corrections accounted for, the rms deviation falls down to ˜1 cm-1. These results represent a drastic improvement over previous theoretical predictions of vibrational levels for all isotopologues of LiH.

  18. Accurate ab initio determination of the adiabatic potential energy function and the Born-Oppenheimer breakdown corrections for the electronic ground state of LiH isotopologues.

    PubMed

    Holka, Filip; Szalay, Péter G; Fremont, Julien; Rey, Michael; Peterson, Kirk A; Tyuterev, Vladimir G

    2011-03-07

    High level ab initio potential energy functions have been constructed for LiH in order to predict vibrational levels up to dissociation. After careful tests of the parameters of the calculation, the final adiabatic potential energy function has been composed from: (a) an ab initio nonrelativistic potential obtained at the multireference configuration interaction with singles and doubles level including a size-extensivity correction and quintuple-sextuple ζ extrapolations of the basis, (b) a mass-velocity-Darwin relativistic correction, and (c) a diagonal Born-Oppenheimer (BO) correction. Finally, nonadiabatic effects have also been considered by including a nonadiabatic correction to the kinetic energy operator of the nuclei. This correction is calculated from nonadiabatic matrix elements between the ground and excited electronic states. The calculated vibrational levels have been compared with those obtained from the experimental data [J. A. Coxon and C. S. Dickinson, J. Chem. Phys. 134, 9378 (2004)]. It was found that the calculated BO potential results in vibrational levels which have root mean square (rms) deviations of about 6-7 cm(-1) for LiH and ∼3 cm(-1) for LiD. With all the above mentioned corrections accounted for, the rms deviation falls down to ∼1 cm(-1). These results represent a drastic improvement over previous theoretical predictions of vibrational levels for all isotopologues of LiH.

  19. High-resolution separation and accurate size determination in pulsed-field gel electrophoresis of DNA. 1. DNA size standards and the effect of agarose and temperature

    SciTech Connect

    Mathew, M.K.; Smith, C.L.; Cantor, C.R. )

    1988-12-27

    Pulsed-field gel electrophoresis (PGF) subjects DNA alternately to two electrical fields to resolve DNA ranging from 10,000 base pairs (10 kb) to 10,000 kb in size. The separations are quite sensitive to a variety of experimental variables. This makes it critical to have a wide range of reliable size standards. A technique is described for preparing mixtures of bacteriophage DNA oligomers that span a size range from monomer to more than 30-mer. The relationship between size and mobility of oligomers of different bacteriophage DNA monomers is generally self-consistent. Thus, these samples can serve as primary length standards for DNAs ranging from 10 kb to more than 1,500 kb. They have been used to estimate the size of the chromosomal DNAs from various Saccharomyces cerevisiae strains and to test the effect of gel concentration and temperature on PFG. DNA resolution during PFG is slightly improved in agarose gels with small pore sizes, in contrast to continuous electrophoresis where the opposite is observed. PFG mobility is surprisingly sensitive to changes in the running temperature.

  20. WE-E-18A-03: How Accurately Can the Peak Skin Dose in Fluoroscopy Be Determined Using Indirect Dose Metrics?

    SciTech Connect

    Jones, A; Pasciak, A

    2014-06-15

    Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that Result in skin reactions can be reached during these procedures. The purpose of this study was to assess the accuracy of different indirect dose estimates and to determine if PSD can be calculated within ±50% for embolization procedures. Methods: PSD were measured directly using radiochromic film for 41 consecutive embolization procedures. Indirect dose metrics from procedures were collected, including reference air kerma (RAK). Four different estimates of PSD were calculated and compared along with RAK to the measured PSD. The indirect estimates included a standard method, use of detailed information from the RDSR, and two simplified calculation methods. Indirect dosimetry was compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the indirect estimates were examined. Results: PSD calculated with the standard calculation method were within ±50% for all 41 procedures. This was also true for a simplified method using a single source-to-patient distance (SPD) for all calculations. RAK was within ±50% for all but one procedure. Cases for which RAK or calculated PSD exhibited large differences from the measured PSD were analyzed, and two causative factors were identified: ‘extreme’ SPD and large contributions to RAK from rotational angiography or runs acquired at large gantry angles. When calculated uncertainty limits [−12.8%, 10%] were applied to directly measured PSD, most indirect PSD estimates remained within ±50% of the measured PSD. Conclusions: Using indirect dose metrics, PSD can be determined within ±50% for embolization procedures, and usually to within ±35%. RAK can be used without modification to set notification limits and substantial radiation dose levels. These results can be extended to similar procedures, including vascular and interventional oncology

  1. Experimental determination of the MHD-EMP effects on power distribution transformers

    SciTech Connect

    McConnell, B.W.; Barnes, P.R. ); Tesche, F.M. , Dallas, TX )

    1991-01-01

    It is a well-established fact that geomagnetic storms influence electrical power transmission and distribution systems. Previous cases of such storms in the northern latitudes have resulted in occasional power disruptions, and in some cases, damage to transformers. These effects are caused by a time variation of the earth's magnetic field creating an induced electric field along the surface of the earth. This E-field acts as a voltage source along long power transmission or distribution lines, and if the line is connected to the earth at both ends, a quasi-dc current can flow. This current can cause unwanted saturation in the magnetic cores of transformers in the power system, and this, in turn produces harmonic distortion and transformer heating. This can lead to system upset (shutdown) and possibly transformer burn-out. The detonation of a high altitude nuclear explosion is also known to affect the magnetosphere, producing late-time variations of the earth's magnetic field for several hundreds of seconds. Known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), or E{sub 3}, this environment is of particular concern to electrical power systems in the event of a nuclear attack. Although the MHD-EMP induced currents can be significantly larger in magnitude, they last for a shorter period of time than do those from a geomagnetic storm. The effect of this environment compounds the adverse effects of the early-time high altitude EMP (HEMP) environment, posing a potentially serious threat to the electrical system. The present paper documents an experimental program designed to better understand the behavior of distribution-class transformers subjected to quasi-dc current excitation. Given the knowledge of the MHD-EMP-induced current flowing in a long power line, and the transformer response characteristics obtained in this program, it will be possible to make more accurate assessments of the behavior of the overall power system to EMP. 7 refs., 5 figs.

  2. Experimental and analytical determination of characteristics affecting light aircraft landing-gear dynamics

    NASA Technical Reports Server (NTRS)

    Fasanella, E. L.; Mcgehee, J. R.; Pappas, M. S.

    1977-01-01

    An experimental and analytical investigation was conducted to determine which characteristics of a light aircraft landing gear influence gear dynamic behavior significantly. The investigation focused particularly on possible modification for load control. Pseudostatic tests were conducted to determine the gear fore-and-aft spring constant, axial friction as a function of drag load, brake pressure-torque characteristics, and tire force-deflection characteristics. To study dynamic tire response, vertical drops were conducted at impact velocities of 1.2, 1.5, and 1.8 m/s onto a level surface; to determine axial-friction effects, a second series of vertical drops were made at 1.5 m/s onto surfaces inclined 5 deg and 10 deg to the horizontal. An average dynamic axial-friction coefficient of 0.15 was obtained by comparing analytical data with inclined surface drop test data. Dynamic strut bending and associated axial friction were found to be severe for the drop tests on the 10 deg surface.

  3. Optimizing the spectrofluorimetric determination of cefdinir through a Taguchi experimental design approach.

    PubMed

    Abou-Taleb, Noura Hemdan; El-Wasseef, Dalia Rashad; El-Sherbiny, Dina Tawfik; El-Ashry, Saadia Mohamed

    2016-05-01

    The aim of this work is to optimize a spectrofluorimetric method for the determination of cefdinir (CFN) using the Taguchi method. The proposed method is based on the oxidative coupling reaction of CFN and cerium(IV) sulfate. The quenching effect of CFN on the fluorescence of the produced cerous ions is measured at an emission wavelength (λ(em)) of 358 nm after excitation (λ(ex)) at 301 nm. The Taguchi orthogonal array L9 (3(4)) was designed to determine the optimum reaction conditions. The results were analyzed using the signal-to-noise (S/N) ratio and analysis of variance (ANOVA). The optimal experimental conditions obtained from this study were 1 mL of 0.2% MBTH, 0.4 mL of 0.25% Ce(IV), a reaction time of 10 min and methanol as the diluting solvent. The calibration plot displayed a good linear relationship over a range of 0.5-10.0 µg/mL. The proposed method was successfully applied to the determination of CFN in bulk powder and pharmaceutical dosage forms. The results are in good agreement with those obtained using the comparison method. Finally, the Taguchi method provided a systematic and efficient methodology for this optimization, with considerably less effort than would be required for other optimizations techniques.

  4. Determination of free vancomycin, ceftriaxone, cefazolin and ertapenem in plasma by ultrafiltration: impact of experimental conditions.

    PubMed

    Kratzer, Alexander; Liebchen, Uwe; Schleibinger, Michael; Kees, Martin G; Kees, Frieder

    2014-06-15

    Ultrafiltration is a rapid and convenient method to determine the free concentrations of drugs. In the present work, we aimed to develop an ultrafiltration method which is appropriate for routine determination of the free fraction of vancomycin and highly protein bound beta-lactams such as ertapenem, ceftriaxone and cefazolin in plasma from intensive care unit patients. Different filter types and experimental conditions (molecular weight cut-off, centrifugal force and time, pH, temperature) were evaluated and found to have influence on the result. In the final protocol, serum or plasma was buffered to pH 7.4-7.5, ultrafiltered at 1000×g at 37°C for 20min using Nanosep Omega 10K filters and subsequently analysed for the antibiotics by RP-HPLC with UV detection. The data from our investigation suggest to aim physiological conditions, i.e. 37°C and pH 7.4, and low to moderate relative centrifugal forces in order to get reliable results. With regard to the chromatographic separation, modulation of the pH in the range of 2.5-7.0 allows to determine several beta-lactams isocratically and/or to avoid interferences by co-administered drugs.

  5. Impact of geometric mean imaging in the accurate determination of partial function in MAG3 renal scanning in a patient with retroperitoneal mass.

    PubMed

    Takesh, Mustafa; Zechmann, Christian M; Haufe, Sabine; Giesel, Frederik L; Kratochwil, Clemens

    2011-01-01

    Liposarcoma frequently occurs in the retroperitoneum and lower extremities, accounting for 20% of all mesenchymal malignancies. Liposarcomas vary by histology and can be classified into four types. Those four types are well differentiated, myxoid/round cell, pleomorphic and dedifferentiated. Due to retroperitoneal location of this tumor, it is expected to affect the kidney position. Renography has provided a unique tool for noninvasive evaluation of various functional parameters e.g. relative renal function. Most renography studies are carried out using the posterior view, under the assumption that the depths of both kidneys are similar so that the radiotracer counts in the region of interest will be attenuated to the same extent. Errors in estimation of the relative renal function may arise if the kidneys are at different depths e.g. secondary to a pushing tumor. Geometric mean imaging from combined anterior and posterior views helps to overcome this issue. This case shows the impact of geometric mean imaging in the truthful determination of partial function in patients with retroperitoneal liposarcoma.

  6. More accurate determination of the quantity of ice crystallized at low cooling rates in the glycerol and 1,2-propanediol aqueous solutions: comparison with equilibrium.

    PubMed

    Boutron, P

    1984-04-01

    It is generally assumed that when cells are cooled at rates close to those corresponding to the maximum of survival, once supercooling has ceased, above the eutectic melting temperature the extracellular ice is in equilibrium with the residual solution. This did not seem evident to us due to the difficulty of ice crystallization in cryoprotective solutions. The maximum quantities of ice crystallized in glycerol and 1,2-propanediol solutions have been calculated from the area of the solidification and fusion peaks obtained with a Perkin-Elmer DSC-2 differential scanning calorimeter. The accuracy has been improved by several corrections: better defined baseline, thermal variation of the heat of fusion of the ice, heat of solution of the water from its melting with the residual solution. More ice crystallizes in the glycerol than in the 1,2-propanediol solutions, of which the amorphous residue contains about 40 to 55% 1,2-propanediol. The equilibrium values are unknown in the presence of 1,2-propanediol. With glycerol, in our experiments, the maximum is first lower than the equilibrium but approaches it as the concentration increases. It is not completely determined by the colligative properties of the solutes.

  7. Accurate determination of arsenic in arsenobetaine standard solutions of BCR-626 and NMIJ CRM 7901-a by neutron activation analysis coupled with internal standard method.

    PubMed

    Miura, Tsutomu; Chiba, Koichi; Kuroiwa, Takayoshi; Narukawa, Tomohiro; Hioki, Akiharu; Matsue, Hideaki

    2010-09-15

    Neutron activation analysis (NAA) coupled with an internal standard method was applied for the determination of As in the certified reference material (CRM) of arsenobetaine (AB) standard solutions to verify their certified values. Gold was used as an internal standard to compensate for the difference of the neutron exposure in an irradiation capsule and to improve the sample-to-sample repeatability. Application of the internal standard method significantly improved linearity of the calibration curve up to 1 microg of As, too. The analytical reliability of the proposed method was evaluated by k(0)-standardization NAA. The analytical results of As in AB standard solutions of BCR-626 and NMIJ CRM 7901-a were (499+/-55)mgkg(-1) (k=2) and (10.16+/-0.15)mgkg(-1) (k=2), respectively. These values were found to be 15-20% higher than the certified values. The between-bottle variation of BCR-626 was much larger than the expanded uncertainty of the certified value, although that of NMIJ CRM 7901-a was almost negligible.

  8. Experimental infection of T4 Acanthamoeba genotype determines the pathogenic potential.

    PubMed

    Alves, Daniella de Sousa Mendes Moreira; Moraes, Aline Silva; Alves, Luciano Moreira; Gurgel-Gonçalves, Rodrigo; Lino Junior, Ruy de Souza; Cuba-Cuba, César Augusto; Vinaud, Marina Clare

    2016-09-01

    T4 is the Acanthamoeba genotype most related to cases of granulomatous amoebic encephalitis (GAE) in immunocompromised patients and of keratitis in contact lens wearers. The determination of the pathogenic potential of Acanthamoeba clinical and environmental isolates using experimental models is extremely important to elucidate the capacity of free-living organisms to establish and cause disease in hosts. The aim of this study was to compare and evaluate the histopathology and culture between two different routes of experimental infection of T4 Acanthamoeba isolated from environmental and clinical source in mice (intracranial and intraperitoneal). Swiss isogenic healthy mice were inoculated with 10(4) trophozoites by intracranial (IC) and intraperitoneal (IP) routes and observed during 21 days. The brains from animals inoculated by the IC route were collected and from the animals of the IP inoculation group, the brains, livers, kidneys, spleens, and lungs were removed. The organs were prepared and appropriately divided to be evaluated with histopathology and culture. There was no significant difference between the inoculation routes in terms of isolates recovery (χ(2) = 0.09; p = 0.76). In the IC group, isolate recovery rate was significantly higher in histopathology than the one achieved by culture (χ(2) = 6.45; p < 0.01). Experimental infection revealed that all isolates inoculated could be considered invasive because it was possible to recover evolutive forms of Acanthamoeba in both routes. This work represents the first in vivo pathogenicity assay of primary isolation source in Central region of Brazil showing in vivo pathogenicity and hematogenous spread capacity of these protozoa, improving the knowledge on free-living amoebae isolates.

  9. Improved morphed potentials for Ar-HBr including scaling to the experimentally determined dissociation energy.

    PubMed

    Wang, Z; McIntosh, A L; McElmurry, B A; Walton, J R; Lucchese, R R; Bevan, J W

    2005-09-15

    A lead salt diode infrared laser spectrometer has been employed to investigate the rotational predissociation in Ar-HBr for transitions up to J' = 79 in the v(1) HBr stretching vibration of the complex using a slit jet and static gas phase. Line-shape analysis and modeling of the predissociation lifetimes have been used to determine a ground-state dissociation energy D(0) of 130(1) cm(-1). In addition, potential energy surfaces based on ab initio calculations are scaled, shifted, and dilated to generate three-dimensional morphed potentials for Ar-HBr that reproduce the measured value of D(0) and that have predictive capabilities for spectroscopic data with nearly experimental uncertainty. Such calculations also provide a basis for making a comprehensive comparison of the different morphed potentials generated using the methodologies applied.

  10. The use of airborne imaging spectrometer data to determine experimentally induced variation in coniferous canopy chemistry

    NASA Technical Reports Server (NTRS)

    Swanberg, Nancy A.; Matson, Pamela A.

    1987-01-01

    It was experimentally determined whether induced differences in forest canopy chemical composition can be detected using data from the Airborne Imaging Spectrometer (AIS). Treatments were applied to an even-aged forest of Douglas fir trees. Work to date has stressed wet chemical analysis of foilage samples and correction of AIS data. Plot treatments were successful in providing a range of foliar N2 concentrations. Much time was spent investigating and correcting problems with the raw AIS data. Initial problems with groups of drop out lines in the AIS data were traced to the tape recorder and the tape drive. Custom adjustment of the tape drive led to recovery of most missing lines. Remaining individual drop out lines were replaced using average of adjacent lines. Application of a notch filter to the Fourier transform of the image in each band satisfactorily removed vertical striping. The aspect ratio was corrected by resampling the image in the line direction using nearest neighbor interpolation.

  11. Experimental and bioinformatic approaches for interrogating protein-protein interactions to determine protein function.

    PubMed

    Droit, Arnaud; Poirier, Guy G; Hunter, Joanna M

    2005-04-01

    An ambitious goal of proteomics is to elucidate the structure, interactions and functions of all proteins within cells and organisms. One strategy to determine protein function is to identify the protein-protein interactions. The increasing use of high-throughput and large-scale bioinformatics-based studies has generated a massive amount of data stored in a number of different databases. A challenge for bioinformatics is to explore this disparate data and to uncover biologically relevant interactions and pathways. In parallel, there is clearly a need for the development of approaches that can predict novel protein-protein interaction networks in silico. Here, we present an overview of different experimental and bioinformatic methods to elucidate protein-protein interactions.

  12. The experimental determination of C lambda using an absorbed dose calorimeter.

    PubMed

    Williams, P C

    1980-01-01

    The absorbed dose conversion factors, C lambda, were introduced, by Greene and Massey, as an interim measure until a primary standard for high energy photon dosimetry could be established. The theoretical basis of these factors has been discussed extensively and a more rigorous definition has emerged. Experiments have been carried out to determine the values of C lambda, for a Tufnol walled, Baldwin-Farmer ionisation chamber over a range of energies from cobalt-60 to 12 MV. The experimental results, based on measurements with a calorimeter, presented here support the more rigorous definition but it is shown that the values obtained depend, to a small extent, on the assumptions made about the detailed construction of the ionisation chamber for which C lambda is measured.

  13. Experimental determination of turbulence in a GH2-GOX rocket combustion chamber

    NASA Technical Reports Server (NTRS)

    Tou, P.; Russell, R.; Ohara, J.

    1974-01-01

    The intensity of turbulence and the Lagrangian correlation coefficient for a gaseous rocket combustion chamber have been determined from the experimental measurements of the tracer gas diffusion. A combination of Taylor's turbulent diffusion theory and Spalding's numerical method for solving the conservation equations of fluid mechanics was used to calculate these quantities. Taylor's theory was extended to consider the inhomogeneity of the turbulence field in the axial direction of the combustion chamber. An exponential function was used to represent the Lagrangian correlation coefficient. The results indicate that the maximum value of the intensity of turbulence is about 15% and the Lagrangian correlation coefficient drops to about 0.12 in one inch of the chamber length.

  14. Numerical and Experimental Determination of the Geometric Far Field for Round Jets

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle; Bridges, James; Brown, Cliff; Khavaran, Abbas

    2003-01-01

    To reduce ambiguity in the reporting of far field jet noise, three round jets operating at subsonic conditions have recently been studied at the NASA Glenn Research Center. The goal of the investigation was to determine the location of the geometric far field both numerically and experimentally. The combination of the WIND Reynolds-Averaged Navier-Stokes solver and the MGBK jet noise prediction code was used for the computations, and the experimental data was collected in the Aeroacoustic Propulsion Laboratory. While noise sources are distributed throughout the jet plume, at great distances from the nozzle the noise will appear to be emanating from a point source and the assumption of linear propagation is valid. Closer to the jet, nonlinear propagation may be a problem, along with the known geometric issues. By comparing sound spectra at different distances from the jet, both from computational methods that assume linear propagation, and from experiments, the contributions of geometry and nonlinearity can be separately ascertained and the required measurement distance for valid experiments can be established. It is found that while the shortest arc considered here (approx. 8D) was already in the geometric far field for the high frequency sound (St greater than 2.0), the low frequency noise due to its extended source distribution reached the geometric far field at or about 50D. It is also found that sound spectra at far downstream angles does not strictly scale on Strouhal number, an observation that current modeling does not capture.

  15. Experimental and theoretical spectroscopic study and structural determination of nickel(II) tridentate Schiff base complexes.

    PubMed

    Kianfar, Ali Hossein; Farrokhpour, Hossein; Dehghani, Parin; Khavasi, Hamid Reza

    2015-11-05

    Some new complexes of [NiL(PR3)] (where L=(E)-1-[(2-amino-5-nitrophenyl)iminio-methyl]naphthalene-2-olate (L(1)), (E)-1-[(2-hydroxiphenyl)iminio-methyl]naphthalene-2-olate (L(2)), R=Bu and Ph) containing tridentate ONN and ONO Schiff bases were synthesized and characterized by IR, UV-Vis, (1)H-NMR spectroscopy and elemental analysis. The geometry of [NiL(1)(PBu3)] and [NiL(2)(PBu3)] complexes were determined by X-ray crystallography. It was indicated that the complexes have a square planar structure and four coordinates in the solid state. Theoretical calculations were also performed to optimize the structures of the ligands and complexes in the gas phase and ethanol solvent, separately to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of the complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification.

  16. Experimental Determination of the Electric Dipole Moment Function of the X Pi-2 Hydroxyl Radical

    NASA Technical Reports Server (NTRS)

    Chackerian, C., Jr.; Goorvitch, D.; Abrams, M. C.; Davis, S. P.; Benidar, A.; Farrenq, R.; Guelachvili, G.; Strawa, Anthony W. (Technical Monitor)

    1995-01-01

    Laboratory infrared emission spectra of X 2piOH obtained with the Solar McMath FTS and the U. Paris (Orsay) FTS are used in an inversion procedure to experimentally determine the electric dipole moment function (EDMF) of the hydroxyl radical. The spectra produced at Kitt Peak show vibrational levels up to v = 10 and rotational lines in the range, -25.5 less than or equal to m less than or equal to 12.5. The following vibrational quantum number ranges were observed: for DELTA v = -1, v prime = 1 - 9, for DELTA v = -2, v prime = 2 - 10, and for DELTA v = - 3, v prime = 6 - 10. The spectra produced at Orsay show DELTA v = -1, with v prime = 1 - 4 and -22.5 less than or equal to m less than or equal to 9.5 as well as DELTA v = 0, with v prime= 1 - 3, and 9.5 less than or equal to m less than or equal to 25.5. The OH rovibrational wavefunctions used in the inversion procedure were calculated using a procedure which reproduces observed rotational constants with a high level of accuracy. Comparisons of our EDMF are made with previous experimental and theoretical work.

  17. Combined Theoretical and Experimental Analysis of Processes Determining Cathode Performance in Solid Oxide Fuel Cells

    SciTech Connect

    Kukla, Maija M.; Kotomin, Eugene Alexej; Merkle, R.; Mastrikov, Yuri; Maier, J.

    2013-02-11

    Solid oxide fuel cells (SOFC) are under intensive investigation since the 1980’s as these devices open the way for ecologically clean direct conversion of the chemical energy into electricity, avoiding the efficiency limitation by Carnot’s cycle for thermochemical conversion. However, the practical development of SOFC faces a number of unresolved fundamental problems, in particular concerning the kinetics of the electrode reactions, especially oxygen reduction reaction. We review recent experimental and theoretical achievements in the current understanding of the cathode performance by exploring and comparing mostly three materials: (La,Sr)MnO3 (LSM), (La,Sr)(Co,Fe)O3 (LSCF) and (Ba,Sr)(Co,Fe)O3 (BSCF). Special attention is paid to a critical evaluation of advantages and disadvantages of BSCF, which shows the best cathode kinetics known so far for oxides. We demonstrate that it is the combined experimental and theoretical analysis of all major elementary steps of the oxygen reduction reaction which allows us to predict the rate determining steps for a given material under specific operational conditions and thus control and improve SOFC performance.

  18. Combined theoretical and experimental analysis of processes determining cathode performance in solid oxide fuel cells.

    PubMed

    Kuklja, M M; Kotomin, E A; Merkle, R; Mastrikov, Yu A; Maier, J

    2013-04-21

    Solid oxide fuel cells (SOFC) are under intensive investigation since the 1980's as these devices open the way for ecologically clean direct conversion of the chemical energy into electricity, avoiding the efficiency limitation by Carnot's cycle for thermochemical conversion. However, the practical development of SOFC faces a number of unresolved fundamental problems, in particular concerning the kinetics of the electrode reactions, especially oxygen reduction reaction. We review recent experimental and theoretical achievements in the current understanding of the cathode performance by exploring and comparing mostly three materials: (La,Sr)MnO3 (LSM), (La,Sr)(Co,Fe)O3 (LSCF) and (Ba,Sr)(Co,Fe)O3 (BSCF). Special attention is paid to a critical evaluation of advantages and disadvantages of BSCF, which shows the best cathode kinetics known so far for oxides. We demonstrate that it is the combined experimental and theoretical analysis of all major elementary steps of the oxygen reduction reaction which allows us to predict the rate determining steps for a given material under specific operational conditions and thus control and improve SOFC performance.

  19. Experimental study on the precise orbit determination of the BeiDou navigation satellite system.

    PubMed

    He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

    2013-03-01

    The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS) network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better.

  20. Experimental Study on the Precise Orbit Determination of the BeiDou Navigation Satellite System

    PubMed Central

    He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

    2013-01-01

    The regional service of the Chinese BeiDou satellite navigation system is now in operation with a constellation including five Geostationary Earth Orbit satellites (GEO), five Inclined Geosynchronous Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Besides the standard positioning service with positioning accuracy of about 10 m, both precise relative positioning and precise point positioning are already demonstrated. As is well known, precise orbit and clock determination is essential in enhancing precise positioning services. To improve the satellite orbits of the BeiDou regional system, we concentrate on the impact of the tracking geometry and the involvement of MEOs, and on the effect of integer ambiguity resolution as well. About seven weeks of data collected at the BeiDou Experimental Test Service (BETS) network is employed in this experimental study. Several tracking scenarios are defined, various processing schemata are designed and carried out; and then, the estimates are compared and analyzed in detail. The results show that GEO orbits, especially the along-track component, can be significantly improved by extending the tracking network in China along longitude direction, whereas IGSOs gain more improvement if the tracking network extends in latitude. The involvement of MEOs and ambiguity-fixing also make the orbits better. PMID:23529116

  1. Optimization of Stripping Voltammetric Sensor by a Back Propagation Artificial Neural Network for the Accurate Determination of Pb(II) in the Presence of Cd(II)

    PubMed Central

    Zhao, Guo; Wang, Hui; Liu, Gang; Wang, Zhiqiang

    2016-01-01

    An easy, but effective, method has been proposed to detect and quantify the Pb(II) in the presence of Cd(II) based on a Bi/glassy carbon electrode (Bi/GCE) with the combination of a back propagation artificial neural network (BP-ANN) and square wave anodic stripping voltammetry (SWASV) without further electrode modification. The effects of Cd(II) in different concentrations on stripping responses of Pb(II) was studied. The results indicate that the presence of Cd(II) will reduce the prediction precision of a direct calibration model. Therefore, a two-input and one-output BP-ANN was built for the optimization of a stripping voltammetric sensor, which considering the combined effects of Cd(II) and Pb(II) on the SWASV detection of Pb(II) and establishing the nonlinear relationship between the stripping peak currents of Pb(II) and Cd(II) and the concentration of Pb(II). The key parameters of the BP-ANN and the factors affecting the SWASV detection of Pb(II) were optimized. The prediction performance of direct calibration model and BP-ANN model were tested with regard to the mean absolute error (MAE), root mean square error (RMSE), average relative error (ARE), and correlation coefficient. The results proved that the BP-ANN model exhibited higher prediction accuracy than the direct calibration model. Finally, a real samples analysis was performed to determine trace Pb(II) in some soil specimens with satisfactory results. PMID:27657083

  2. Optimization of Stripping Voltammetric Sensor by a Back Propagation Artificial Neural Network for the Accurate Determination of Pb(II) in the Presence of Cd(II).

    PubMed

    Zhao, Guo; Wang, Hui; Liu, Gang; Wang, Zhiqiang

    2016-09-21

    An easy, but effective, method has been proposed to detect and quantify the Pb(II) in the presence of Cd(II) based on a Bi/glassy carbon electrode (Bi/GCE) with the combination of a back propagation artificial neural network (BP-ANN) and square wave anodic stripping voltammetry (SWASV) without further electrode modification. The effects of Cd(II) in different concentrations on stripping responses of Pb(II) was studied. The results indicate that the presence of Cd(II) will reduce the prediction precision of a direct calibration model. Therefore, a two-input and one-output BP-ANN was built for the optimization of a stripping voltammetric sensor, which considering the combined effects of Cd(II) and Pb(II) on the SWASV detection of Pb(II) and establishing the nonlinear relationship between the stripping peak currents of Pb(II) and Cd(II) and the concentration of Pb(II). The key parameters of the BP-ANN and the factors affecting the SWASV detection of Pb(II) were optimized. The prediction performance of direct calibration model and BP-ANN model were tested with regard to the mean absolute error (MAE), root mean square error (RMSE), average relative error (ARE), and correlation coefficient. The results proved that the BP-ANN model exhibited higher prediction accuracy than the direct calibration model. Finally, a real samples analysis was performed to determine trace Pb(II) in some soil specimens with satisfactory results.

  3. Novel, Precise, Accurate Ion-Pairing Method to Determine the Related Substances of the Fondaparinux Sodium Drug Substance: Low-Molecular-Weight Heparin

    PubMed Central

    Deshpande, Amol A.; Madhavan, P.; Deshpande, Girish R.; Chandel, Ravi Kumar; Yarbagi, Kaviraj M.; Joshi, Alok R.; Moses Babu, J.; Murali Krishna, R.; Rao, I. M.

    2016-01-01

    Fondaparinux sodium is a synthetic low-molecular-weight heparin (LMWH). This medication is an anticoagulant or a blood thinner, prescribed for the treatment of pulmonary embolism and prevention and treatment of deep vein thrombosis. Its determination in the presence of related impurities was studied and validated by a novel ion-pair HPLC method. The separation of the drug and its degradation products was achieved with the polymer-based PLRPs column (250 mm × 4.6 mm; 5 μm) in gradient elution mode. The mixture of 100 mM n-hexylamine and 100 mM acetic acid in water was used as buffer solution. Mobile phase A and mobile phase B were prepared by mixing the buffer and acetonitrile in the ratio of 90:10 (v/v) and 20:80 (v/v), respectively. Mobile phases were delivered in isocratic mode (2% B for 0–5 min) followed by gradient mode (2–85% B in 5–60 min). An Evaporative Light Scattering Detector (ELSD) was connected to the LC system to detect the responses of chromatographic separation. Further, the drug was subjected to stress studies for acidic, basic, oxidative, photolytic, and thermal degradations as per ICH guidelines and the drug was found to be labile in acid, base hydrolysis, and oxidation, while stable in neutral, thermal, and photolytic degradation conditions. The method provided linear responses over the concentration range of the LOQ to 0.30% for each impurity with respect to the analyte concentration of 12.5 mg/mL, and regression analysis showed a correlation coefficient value (r2) of more than 0.99 for all the impurities. The LOD and LOQ were found to be 1.4 µg/mL and 4.1 µg/mL, respectively, for fondaparinux. The developed ion-pair method was validated as per ICH guidelines with respect to accuracy, selectivity, precision, linearity, and robustness. PMID:27110496

  4. Experimental determination of solvent-water partition coefficients and Abraham parameters for munition constituents.

    PubMed

    Liang, Yuzhen; Kuo, Dave T F; Allen, Herbert E; Di Toro, Dominic M

    2016-10-01

    There is concern about the environmental fate and effects of munition constituents (MCs). Polyparameter linear free energy relationships (pp-LFERs) that employ Abraham solute parameters can aid in evaluating the risk of MCs to the environment. However, poor predictions using pp-LFERs and ABSOLV estimated Abraham solute parameters are found for some key physico-chemical properties. In this work, the Abraham solute parameters are determined using experimental partition coefficients in various solvent-water systems. The compounds investigated include hexahydro-1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), hexahydro-1,3-dinitroso-5- nitro-1,3,5-triazine (DNX), 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), and 4-nitroanisole. The solvents in the solvent-water systems are hexane, dichloromethane, trichloromethane, octanol, and toluene. The only available reported solvent-water partition coefficients are for octanol-water for some of the investigated compounds and they are in good agreement with the experimental measurements from this study. Solvent-water partition coefficients fitted using experimentally derived solute parameters from this study have significantly smaller root mean square errors (RMSE = 0.38) than predictions using ABSOLV estimated solute parameters (RMSE = 3.56) for the investigated compounds. Additionally, the predictions for various physico-chemical properties using the experimentally derived solute parameters agree with available literature reported values with prediction errors within 0.79 log units except for water solubility of RDX and HMX with errors of 1.48 and 2.16 log units respectively. However, predictions using ABSOLV estimated solute parameters have larger prediction errors of up to 7.68 log units. This large discrepancy is probably due to the missing R2NNO2

  5. Determination of calibration constants for the hole-drilling residual stress measurement technique applied to orthotropic composites. II - Experimental evaluations

    NASA Technical Reports Server (NTRS)

    Prasad, C. B.; Prabhakaran, R.; Tompkins, S.

    1987-01-01

    The first step in the extension of the semidestructive hole-drilling technique for residual stress measurement to orthotropic composite materials is the determination of the three calibration constants. Attention is presently given to an experimental determination of these calibration constants for a highly orthotropic, unidirectionally-reinforced graphite fiber-reinforced polyimide composite. A comparison of the measured values with theoretically obtained ones shows agreement to be good, in view of the many possible sources of experimental variation.

  6. Lab-scale experimental strategy for determining micropollutant partition coefficient and biodegradation constants in activated sludge.

    PubMed

    Pomiès, M; Choubert, J M; Wisniewski, C; Miège, C; Budzinski, H; Coquery, M

    2015-03-01

    The nitrifying/denitrifying activated sludge process removes several micropollutants from wastewater by sorption onto sludge and/or biodegradation. The objective of this paper is to propose and evaluate a lab-scale experimental strategy for the determination of partition coefficient and biodegradation constant for micropollutant with an objective of modelling their removal. Four pharmaceutical compounds (ibuprofen, atenolol, diclofenac and fluoxetine) covering a wide hydrophobicity range (log Kow from 0.16 to 4.51) were chosen. Dissolved and particulate concentrations were monitored for 4 days, inside two reactors working under aerobic and anoxic conditions, and under different substrate feed conditions (biodegradable carbon and nitrogen). We determined the mechanisms responsible for the removal of the target compounds: (i) ibuprofen was biodegraded, mainly under aerobic conditions by cometabolism with biodegradable carbon, whereas anoxic conditions suppressed biodegradation; (ii) atenolol was biodegraded under both aerobic and anoxic conditions (with a higher biodegradation rate under aerobic conditions), and cometabolism with biodegradable carbon was the main mechanism; (iii) diclofenac and fluoxetine were removed by sorption only. Finally, the abilities of our strategy were evaluated by testing the suitability of the parameters for simulating effluent concentrations and removal efficiency at a full-scale plant.

  7. An Experimental and Analytical Evaluation of a Biaxial Test for Determining Shear Properties of Composite Materials

    NASA Technical Reports Server (NTRS)

    Kennedy, John M.; Barnett, Terry R.

    1988-01-01

    The results of an experimental and analytical investigation of a biaxial tension/compression test for determining shear properties of composite materials are reported. Using finite element models of isotropic and orthotropic laminates, a specimen geometry was optimized. A kinematic fixture was designed to introduce an equal and opposite pair of forces into a specimen with a one inch square test section. Aluminum and several composite laminates with the optimized geometry and a configuration with large stress gradients were tested in the fixture. The specimens were instrumented with strain gages in the center of the test section for shear stiffness measurements. Pure shear strain was measured. The results from the experiments correlated well with finite element results. Failure of the specimens occurred through the center of the test section and appeared to have initiated at the high stress points. The results lead to the conclusion that the optimized specimen is suitable for determining shear modulus for composite materials. Further revisions to the specimen geometry are necessary if the method is to give shear strength data.

  8. Experimental determination of the deuterium binding energy with vacancies in tungsten

    NASA Astrophysics Data System (ADS)

    Zibrov, M.; Ryabtsev, S.; Gasparyan, Yu.; Pisarev, A.

    2016-08-01

    Deuterium (D) interaction with vacancies in tungsten (W) was studied using thermal desorption spectroscopy (TDS). In order to obtain a TDS spectrum with a prominent peak corresponding to D release from vacancies, a special procedure comprising damaging of a recrystallized W sample by low fluences of 10 keV/D ions, its annealing, and subsequent low-energy ion implantation, was utilized. This experimental sequence was performed several times in series; the only difference was the TDS heating rate that varied in the range of 0.15-4 K/s. The sum of the D binding energy (Eb) with vacancies and the activation energy for D diffusion (ED) in W was then directly determined from the slope of the Arrhenius-like plot ln(β / Tm2) versus 1/Tm, where β - heating rate and Tm - position of the respective peak in the TDS spectrum. The determined value of Eb + ED was 1.56 ± 0.06 eV.

  9. Computational tools for experimental determination and theoretical prediction of protein structure

    SciTech Connect

    O`Donoghue, S.; Rost, B.

    1995-12-31

    This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. The authors intend to review the state of the art in the experimental determination of protein 3D structure (focus on nuclear magnetic resonance), and in the theoretical prediction of protein function and of protein structure in 1D, 2D and 3D from sequence. All the atomic resolution structures determined so far have been derived from either X-ray crystallography (the majority so far) or Nuclear Magnetic Resonance (NMR) Spectroscopy (becoming increasingly more important). The authors briefly describe the physical methods behind both of these techniques; the major computational methods involved will be covered in some detail. They highlight parallels and differences between the methods, and also the current limitations. Special emphasis will be given to techniques which have application to ab initio structure prediction. Large scale sequencing techniques increase the gap between the number of known proteins sequences and that of known protein structures. They describe the scope and principles of methods that contribute successfully to closing that gap. Emphasis will be given on the specification of adequate testing procedures to validate such methods.

  10. Simple experimental method for alpha particle range determination in lead iodide films

    SciTech Connect

    Dmitriev, Yuri; Bennett, Paul R.; Cirignano, Leonard J.; Klugerman, Mikhail; Shah, Kanai S.

    2007-05-15

    An experimental method for determining the range of alpha particles in films based on I-V{sub s} analysis has been suggested. The range of 5.5 MeV alpha particles in PbI{sub 2} films determined by this technique is 30{+-}5 {mu}m, and this value is in agreement with the value calculated by SRIM (the stopping and range of ions in matter), r=24 {mu}m in PbI{sub 2}. More than 100 I-V{sub s} of PbI{sub 2} films with different thicknesses and quality have been analyzed, and the influence of alpha particle radiation on PbI{sub 2} I-V{sub s} curves has been studied. Developed analytical methods (dependence of current density on electric field and conception of surface defects) were used, and the method limitations are discussed. It was shown that I-V{sub s} demonstrate the tendency to obey Ohm's law under alpha radiation. On the other hand, dark conductivity of the lead iodide films shows a typical impure character that can lead to an overestimation of the alpha particles' range in PbI{sub 2} films. After films were exposed to alpha radiation, the dark resistivity and I-V shape of some films improved. Also, a weak decrease of the charge carrier concentration, due to a decrease of the ''surface defect'' concentration (''surface refining''), was registered after successive measurements of I-V{sub s}.

  11. Experimental determination of the thermodynamic parameters affecting the adsorption behaviour and dispersion effectiveness of PCE superplasticizers

    SciTech Connect

    Plank, J.; Sachsenhauser, B.; Reese, J. de

    2010-05-15

    For adsorption of three different allylether-based PCE superplasticizers on CaCO{sub 3} surface, the thermodynamic parameters DELTAH, DELTAS and DELTAG were determined experimentally. The GIBBS standard free energy of adsorption DELTAG{sub 0ads}, the standard enthalpy of adsorption DELTAH{sub 0ads} and the standard entropy of adsorption DELTAS{sub 0ads} applying to an unoccupied CaCO{sub 3} surface were obtained via a linear regression of ln K (equilibrium constant) versus 1 / T (VAN'T HOFF plot). Additionally, the thermodynamic parameters characteristic for a CaCO{sub 3} surface loaded already with polymer (isosteric conditions) were determined using a modified CLAUSIUS-CLAPEYRON equation. For all PCE molecules, negative DELTAG values were found, indicating that adsorption of these polymers is energetically favourable and a spontaneous process. Adsorption of PCEs possessing short side chains is mainly instigated by electrostatic attraction and a release of enthalpy. Contrary to this, adsorption of PCEs with long side chains occurs because of a huge gain in entropy. The gain in entropy results from the release of counter ions attached to the carboxylate groups of the polymer backbone and of water molecules and ions adsorbed on the CaCO{sub 3} surface. With increased surface loading, however, DELTAG{sub isosteric} decreases and adsorption ceases when DELTAG becomes 0. The presence of Ca{sup 2+} ions in the pore solution strongly impacts PCE adsorption, due to complexation of carboxylate groups and a reduced anionic charge amount of the molecule. In the presence of Ca{sup 2+}, adsorption of allylether-based PCEs is almost exclusively driven by a gain in entropy. Consequently, PCEs should produce a strong entropic effect upon adsorption to be effective cement dispersants. Molecular architecture, anionic charge density and molecular weight as well as the type of anchor groups present in a superplasticizer determine whether enthalpy or entropy is the dominant force for

  12. Statistical analysis of accurate prediction of local atmospheric optical attenuation with a new model according to weather together with beam wandering compensation system: a season-wise experimental investigation

    NASA Astrophysics Data System (ADS)

    Arockia Bazil Raj, A.; Padmavathi, S.

    2016-07-01

    Atmospheric parameters strongly affect the performance of Free Space Optical Communication (FSOC) system when the optical wave is propagating through the inhomogeneous turbulent medium. Developing a model to get an accurate prediction of optical attenuation according to meteorological parameters becomes significant to understand the behaviour of FSOC channel during different seasons. A dedicated free space optical link experimental set-up is developed for the range of 0.5 km at an altitude of 15.25 m. The diurnal profile of received power and corresponding meteorological parameters are continuously measured using the developed optoelectronic assembly and weather station, respectively, and stored in a data logging computer. Measured meteorological parameters (as input factors) and optical attenuation (as response factor) of size [177147 × 4] are used for linear regression analysis and to design the mathematical model that is more suitable to predict the atmospheric optical attenuation at our test field. A model that exhibits the R2 value of 98.76% and average percentage deviation of 1.59% is considered for practical implementation. The prediction accuracy of the proposed model is investigated along with the comparative results obtained from some of the existing models in terms of Root Mean Square Error (RMSE) during different local seasons in one-year period. The average RMSE value of 0.043-dB/km is obtained in the longer range dynamic of meteorological parameters variations.

  13. Experimental determination of in situ utilization of lunar regolith for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Richter, Scott W.

    1993-01-01

    A Lunar Thermal Energy from Regolith (LUTHER) experiment has been designed and fabricated at the NASA Lewis Research Center to determine the feasibility of using lunar soil as thermal energy storage media. The experimental apparatus includes an alumina ceramic canister (25.4 cm diameter by 45.7 cm length) which contains simulated lunar regolith, a heater (either radiative or conductive), 9 heat shields, a heat transfer cold jacket, and 19 type B platinum rhodium thermocouples. The simulated lunar regolith is a basalt, mined and processed by the University of Minnesota, that closely resembles the lunar basalt returned to earth by the Apollo missions. The experiment will test the effects of vacuum, particle size, and density on the thermophysical properties of the regolith. The properties include melt temperature (range), specific heat, thermal conductivity, and latent heat of storage. Two separate tests, using two different heaters, will be performed to study the effect of heating the system using radiative and conductive heat transfer. The physical characteristics of the melt pattern, material compatibility of the molten regolith, and the volatile gas emission will be investigated by heating a portion of the lunar regolith to its melting temperature (1435 K) in a 10(exp -4) pascal vacuum chamber, equipped with a gas spectrum analyzer. A finite differencing SINDA model was developed at NASA Lewis Research Center to predict the performance of the LUTHER experiment. The analytical results of the code will be compared with the experimental data generated by the LUTHER experiment. The code will predict the effects of vacuum, particle size, and density has on the heat transfer to the simulated regolith.

  14. Theoretical and experimental determination of dosimetric characteristics for brachyseed Pd-103, model Pd-1, source.

    PubMed

    Meigooni, Ali S; Zhang, Hualin; Perry, Candace; Dini, Sharifeh A; Koona, Rafiq A

    2003-05-01

    Dosimetric characteristics of the BrachySeed Pd-103, Model Pd-1 source have been determined using both theoretical and experimental methods. Dose rate constant, radial dose function, and anisotropy functions of the source have been obtained following the TG-43 recommendations. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with their 1999 Standard. Measurements were performed in Solid Water using LiF TLD chips. Theoretical simulation calculations were performed in both Solid Water and water phantom materials using MCNP4C2 Monte Carlo code using DLC-200 interaction data. The results of the Monte Carlo simulation indicated a dose rate constant of 0.65 cGyh(-1)U(-1) and 0.61 cGyh (-1)U(-1) in water and Solid Water, respectively. The measured dose rate constant in Solid Water was found to be 0.63+/-7% cGyh (-1)U(-1), which is within the experimental uncertainty of the Monte-Carlo simulated results. The anisotropy functions of the source were calculated in both water and in Solid Water at the radial distances of 1 to 7 cm. Measurements were made in Solid Water at distances of 2, 3, 5, and 7 cm. The Monte-Carlo calculated anisotropy constant of the new source was found to be 0.98 in water. The tabulated data and 5th order polynomial fit coefficients for the radial dose function along with the dose rate constant and anisotropy functions are provided to support clinical use of this source.

  15. Experimental Determination of in Situ Utilization of Lunar Regolith for Thermal Energy Storage

    NASA Technical Reports Server (NTRS)

    Richter, Scott W.

    1993-01-01

    A Lunar Thermal Energy from Regolith (LUTHER) experiment has been designed and fabricated at the NASA Lewis Research Center to determine the feasibility of using lunar soil as thermal energy storage media. The experimental apparatus includes an alumina ceramic canister (25.4 cm diameter by 45.7 cm length) which contains simulated lunar regolith, a heater (either radiative or conductive), 9 heat shields, a heat transfer cold jacket, and 19 type B platinum rhodium thermocouples. The simulated lunar regolith is a basalt, mined and processed by the University of Minnesota, that closely resembles the lunar basalt returned to earth by the Apollo missions. The experiment will test the effects of vacuum, particle size, and density on the thermophysical properties of the regolith. The properties include melt temperature (range), specific heat, thermal conductivity, and latent heat of storage. Two separate tests, using two different heaters, will be performed to study the effect of heating the system using radiative and conductive heat transfer. The physical characteristics of the melt pattern, material compatibility of the molten regolith, and the volatile gas emission will be investigated by heating a portion of the lunar regolith to its melting temperature (1435 K) in a 10(exp -4) pascal vacuum chamber, equipped with a gas spectrum analyzer. A finite differencing SINDA model was developed at NASA Lewis Research Center to predict the performance of the LUTHER experiment. The analytical results of the code will be compared with the experimental data generated by the LUTHER experiment. The code will predict the effects of vacuum, particle size, and density has on the heat transfer to the simulated regolith.

  16. Experimental determination of the temperature dependence of water activities for a selection of aqueous organic solutions

    NASA Astrophysics Data System (ADS)

    Ganbavale, G.; Marcolli, C.; Krieger, U. K.; Zuend, A.; Stratmann, G.; Peter, T.

    2014-09-01

    This work presents experimental data of the temperature dependence of water activity in aqueous organic solutions relevant for tropospheric conditions (200-273 K). Water activity (aw) at low temperatures (T) is a crucial parameter for predicting homogeneous ice nucleation. We investigated temperature-dependent water activities, ice freezing and melting temperatures of solutions, and vapour pressures of a selection of atmospherically relevant aqueous organic systems. To measure aw over a wide composition range and with a focus on low temperatures, we use various aw measurement techniques and instruments: a dew point water activity meter, an electrodynamic balance (EDB), differential scanning calorimetry (DSC), and a setup to measure the total gas phase pressure at equilibrium over aqueous solutions. Water activity measurements were performed for aqueous multicomponent and multifunctional organic mixtures containing the functional groups typically found in atmospheric organic aerosols, such as hydroxyl, carboxyl, ketone, ether, ester, and aromatic groups. The aqueous organic systems studied at several fixed compositions over a considerable temperature range differ significantly in their temperature dependence. Aqueous organic systems of 1,4-butanediol and methoxyacetic acid show a moderate decrease in aw with decreasing temperature. The aqueous M5 system (a multicomponent system containing five different dicarboxylic acids) and aqueous 2-(2-ethoxyethoxy)ethanol solutions both show a strong increase of water activity with decreasing temperature at high solute concentrations for T < 270 K and T < 260 K, respectively. These measurements show that the temperature trend of aw can be reversed at low temperatures and that linear extrapolations of high-temperature data may lead to erroneous predictions. To avoid this, experimentally determined aw at low temperature are needed to improve thermodynamic models towards lower temperatures and for improved predictions of the ice

  17. Experimental determination of the temperature dependence of water activities for a selection of aqueous organic solutions

    NASA Astrophysics Data System (ADS)

    Ganbavale, G.; Marcolli, C.; Krieger, U. K.; Zuend, A.; Stratmann, G.; Peter, T.

    2014-05-01

    This work presents experimental data of the temperature dependence of water activity in aqueous organic solutions relevant for tropospheric conditions (200-273 K). Water activity (aw) at low temperatures (T) is a crucial parameter for predicting homogeneous ice nucleation. We investigated temperature dependent water activities, ice freezing and melting temperatures of solutions, and vapour pressures of a selection of atmospherically relevant aqueous organic systems. To measure aw over a wide composition range and with a focus on low temperatures, we use various aw measurement techniques and instruments: a dew point water activity meter, an electrodynamic balance (EDB), differential scanning calorimetry (DSC), and a setup to measure the total gas phase pressure at equilibrium over aqueous solutions. Water activity measurements were performed for aqueous multicomponent and multifunctional organic mixtures containing the functional groups typically found in atmospheric organic aerosols, such as hydroxyl, carboxyl, ketone, ether, ester, and aromatic groups. The aqueous organic systems studied at several fixed compositions over a considerable temperature range differ significantly in their temperature dependence. Aqueous organic systems of 1,4-butanediol and methoxyacetic acid show a moderate decrease in aw with decreasing temperature. The aqueous M5 system (a multicomponent system containing five different dicarboxylic acids) and aqueous 2-(2-ethoxyethoxy)ethanol solutions both show a strong increase of water activity with decreasing temperature at high solute concentrations for T<270 K and T<260 K, respectively. These measurements show that the temperature trend of aw can be reversed at low temperatures and that linear extrapolations of high temperature data may lead to erroneous predictions. To avoid this, experimentally determined aw at low temperature are needed to improve thermodynamic models towards lower temperatures and for improved predictions of the ice

  18. Experimental Spinel Standards for Ferric Iron (Fe3+) Determination During Peridotite Partial Melting

    NASA Astrophysics Data System (ADS)

    Wenz, M. D.; Sorbadere, F.; Rosenthal, A.; Frost, D. J.; McCammon, C. A.

    2014-12-01

    The presence of ferric iron (Fe3+) in the mantle plays a significant role in the oxygen fugacity (fO2) of the Earth's interior. This has a wide range of implications for Earth related processes ranging from the composition of the atmosphere to magmatic phase relations during melting and crystallization processes [1]. A major source of Earth's mantle magmas is spinel peridotite. Despite its low abundance, spinel (Fe3+/ƩFe = 15-34%, [2]) is the main contributor of Fe3+to the melt upon partial melting. Analyses of Fe3+ on small areas of spinel and melt are required to study the Fe3+ behavior during partial melting of spinel peridotite. Fe K-edge X-ray Absorption Near Edge Structure (XANES) combines both high precision and small beam size, but requires standards with a wide range of Fe3+ content to obtain good calibration. Glasses with varying Fe3+ content are easily synthesized [3, 4]. Spinel, however, presents a challenge for experimental standards due to the low diffusion of Cr and Al preventing compositional homogeneity. Natural spinel standards are often used, but only cover a narrow Fe3+ range. Thus, there is a need for better experimental spinel standards over a wider range of fO2. Our study involves making experimental mantle spinels with variable Fe3+ content. We used a sol-gel auto-combustion method to synthesize our starting material [5]. FMQ-2, FMQ+0, and air fO2 conditions were established using a gas mixing furnace. Piston cylinder experiments were performed at 1.5GPa, and 1310 -1370°C to obtain solid material for XANES. To maintain distinct oxidizing conditions, three capsules were used: graphite for reduced, Re for intermediate and AuPd for oxidized conditions. The spinels were analyzed by Mössbauer spectroscopy. Fe3+/ƩFe ranged from 0.3 to 0.6. These values are consistent with the Fe edge position obtained using XANES analyses, between 7130 and 7132 eV, respectively. Our spinels are thus suitable standards for Fe3+ measurements in peridotite

  19. Experimental Study for the Determination of the Turbulence Onset in Natural Convection on Inclined Plates

    NASA Astrophysics Data System (ADS)

    Pérez Grande, Isabel; Rodriguez Sevillano, Angel; Meseguer, Jos

    In June, 8th, 2009 the balloon-borne solar telescope SUNRISE was launched from the Swedish Space Corporation balloon facility Esrange. A telescope with a mirror of 1 m in diameter ob-served the Sun during six days until the mission was terminated in Canada. The design process of SUNRISE and of any optical telescope requires the analysis of the effect of surrounding air on the quality of images. The turbulence encountered in the local telescope environment de-grades its optical performance. This phenomenon called `seeing' consists of optical aberrations produced by density non-homogeneities in the air along the optical path. The refraction index of air changes due to thermal non-uniformities so that the wavefront incident on the mirror is randomly distorted, and therefore, images are altered. When telescope mirrors are heated, as it happens in solar telescopes, and therefore they are at a temperature different from the environment's, natural convection occurs. It is then crucial to know whether the flow in front of the mirror is laminar or turbulent. After reviewing the literature, it was found that the scattering of results about the onset of the transition gives only rough orders of magnitude of the values of the critical Grashof numbers. Aiming to obtain more information about it, the problem of determination of the turbulence onset in natural convection on heated inclined plates in air environment was experimentally revisited. The transition has been determined from hot wire velocity measurements. The onset of turbulence has been considered to take place where velocity perturbations start to grow. Experiments have shown that the onset depends not only on the Grashof number, but also on other parameters as the temperature difference between the heated plate and the surrounding air. A correlation between dimensionless Grashof and Reynolds numbers has been obtained, fitting extraordinarily well the experimental data. The results are obtained in terms of non

  20. Determining the Mechanical Constitutive Properties of Metals as Function of Strain Rate and temperature: A Combined Experimental and Modeling Approach

    SciTech Connect

    Ian Robertson

    2007-04-28

    Development and validation of constitutive models for polycrystalline materials subjected to high strain-rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions. To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be integrated fully with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experiment is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models. One aspect of the program involves the direct observation of specific mechanisms of micro-plasticity, as these indicate the boundary value problem that should be addressed. This focus on the pre-yield region in the quasi-static effort (the elasto-plastic transition) is also a tractable one from an

  1. Theoretical and experimental determination of dosimetric characteristics for ADVANTAGE Pd-103 brachytherapy source.

    PubMed

    Meigooni, Ali S; Dini, Sharifeh A; Awan, Shahid B; Dou, Kai; Koona, Rafiq A

    2006-08-01

    ADVANTAGE Pd-103 brachytherapy source has been recently introduced by IsoAid for prostate permanent implants. Dosimetric characteristics (Dose rate constant, radial dose function, 2D-, and 1D-anisotropy functions) of this source model have been determined using both theoretical and experimental methods, following the updated TG-43U1 protocol. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with the 1999 Standards. Measurements were performed in Solid Water using LiF TLD chips and the theoretical calculations were performed in Solid Water and liquid water phantom materials using PTRAN Monte Carlo code. The results of the Monte Carlo simulation have shown a dose rate constant of 0.69 cGyh(-1) U(-1) in liquid water and 0.67 cGyh(-1) U(-1) in Solid Water medium. The measured dose rate constant in Solid Water was found to be 0.68+/-8% cGyh(-1) U(-1), which is in a good agreement (within +/-5%) to the Monte Carlo simulated data. The 2D- and 1D-anisotropy functions of the ADVANTAGE Pd-103 source were calculated for radial distances ranging from 0.5 to 5.0 cm. Radial dose function was determined for radial distances ranging from 0.2 to 8.0 cm using line source approximation. All these calculations are based on L(eff) equal to 3.61 cm, calculated following TG-43U1 recommendations. The tabulated data for 2D-anisotropy function, 1D-anisotropy function, dose rate constant and radial dose function have been produced for clinical application of this source model.

  2. Bench-scale experimental determination of the thermal diffusivity of crushed tuff

    SciTech Connect

    Ryder, E.E.; Finley, R.E.; George, J.T.; Ho, C.K.; Longenbaugh, R.S.; Connolly, J.R.

    1996-06-01

    A bench-scale experiment was designed and constructed to determine the effective thermal diffusivity of crushed tuff. Crushed tuff particles ranging from 12.5 mm to 37.5 mm (0.5 in. to 1.5 in.) were used to fill a cylindrical volume of 1.58 m{sup 3} at an effective porosity of 0.48. Two iterations of the experiment were completed; the first spanning approximately 502 hours and the second 237 hours. Temperatures near the axial heater reached 700 degrees C, with a significant volume of the test bed exceeding 100 degrees C. Three post-test analysis techniques were used to estimate the thermal diffusivity of the crushed tuff. The first approach used nonlinear parameter estimation linked to a one dimensional radial conduction model to estimate thermal diffusivity from the first 6 hours of test data. The second method used the multiphase TOUGH2 code in conjunction with the first 20 hours of test data not only to estimate the crushed tuffs thermal diffusivity, but also to explore convective behavior within the test bed. Finally, the nonlinear conduction code COYOTE-II was used to determine thermal properties based on 111 hours of cool-down data. The post-test thermal diffusivity estimates of 5.0 x 10-7 m{sup 2}/s to 6.6 x 10-7 m{sup 2}/s were converted to effective thermal conductivities and compared to estimates obtained from published porosity-based relationships. No obvious match between the experimental data and published relationships was found to exist; however, additional data for other particle sizes and porosities are needed.

  3. Experimental determination of in situ utilization of lunar regolith for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Richter, Scott W.

    A Lunar Thermal Energy from Regolith (LUTHER) experiment has been designed and fabricated at the NASA Lewis Research Center to determine the feasibility of using lunar soil as thermal energy storage media. The experimental apparatus includes an alumina ceramic canister which contains simulated lunar regolith, a heater, nine heat shields, a heat transfer cold jacket, and 19 type-B platinum rhodium thermocouples. The simulated lunar regolith is a basalt that closely resembles the lunar basalt returned to earth by the Apollo missions. The experiment will test the effects of vacuum, particle size, and density on the thermophysical properties of the regolith, which include melt temperature, specific heat thermal conductivity, and latent heat of storage. Two separate tests, using two different heaters, will be performed to study the effect of heating the system using radiative and conductive heat transfer. A finite differencing SINDA model was developed at NASA Lewis Research Center to predict the performance of the LUTHER experiment. The code will predict the effects of vacuum, particle size, and density has on the heat transfer to the simulated regolith.

  4. Experimental determination of optimum gutter brush parameters and road sweeping criteria for different types of waste.

    PubMed

    Abdel-Wahab, Magd M; Wang, Chong; Vanegas-Useche, Libardo V; Parker, Graham A

    2011-06-01

    The removal ability of gutter brushes for road sweeping for various debris types and different sweeping parameters is studied through experimental tests. The brushing test rig used comprises two commercial gutter brushes, a concrete test bed, and an asphalt test road with a gutter of 0.25 cm width and 10° slope. The brush-surface contact area is determined by sweeping sand on the concrete test bed. Sweeping problems are identified and discussed, and sweeping criteria for the different debris types are suggested. Also, optimum sweeping parameters are proposed for each debris type. In addition, debris removal mechanisms are discussed and analysed. The results indicate that for large heavy debris such as stones and gravel, it is not difficult to achieve large removal forces, because the steel bristles are relatively stiff. Conversely, high removal forces are not needed for particles of millimetre or micron sizes, but bristle curvature has to be appropriate to remove particles from road concavities. Finally, it is found that mud, especially dry mud on a rough surface, is the hardest debris to sweep, requiring a brush with a large tilt angle and a very large penetration to produce large removal forces.

  5. Experimental determination of in situ utilization of lunar regolith for thermal energy storage

    NASA Technical Reports Server (NTRS)

    Richter, Scott W.

    1992-01-01

    A Lunar Thermal Energy from Regolith (LUTHER) experiment has been designed and fabricated at the NASA Lewis Research Center to determine the feasibility of using lunar soil as thermal energy storage media. The experimental apparatus includes an alumina ceramic canister which contains simulated lunar regolith, a heater, nine heat shields, a heat transfer cold jacket, and 19 type-B platinum rhodium thermocouples. The simulated lunar regolith is a basalt that closely resembles the lunar basalt returned to earth by the Apollo missions. The experiment will test the effects of vacuum, particle size, and density on the thermophysical properties of the regolith, which include melt temperature, specific heat thermal conductivity, and latent heat of storage. Two separate tests, using two different heaters, will be performed to study the effect of heating the system using radiative and conductive heat transfer. A finite differencing SINDA model was developed at NASA Lewis Research Center to predict the performance of the LUTHER experiment. The code will predict the effects of vacuum, particle size, and density has on the heat transfer to the simulated regolith.

  6. Optimization of experimental parameters to determine the jetting regimes in electrohydrodynamic printing.

    PubMed

    Lee, Ayoung; Jin, Howon; Dang, Hyun-Woo; Choi, Kyung-Hyun; Ahn, Kyung Hyun

    2013-11-05

    The harmony of ink and printing method is of importance in producing on-demand droplets and jets of ink. Many factors including the material properties, the processing conditions, and the nozzle geometry affect the printing quality. In electrohydrodynamic (EHD) printing where droplets or jets are generated by the electrostatic force, the physical as well as the electrical properties of the fluid should be taken into account to achieve the desired performance. In this study, a systematic approach was suggested for finding the processing windows of the EHD printing. Six dimensionless parameters were organized and applied to the printing system of ethanol/terpineol mixtures. On the basis of the correlation of the dimensionless voltage and the charge relaxation length, the jet diameter of cone-jet mode was characterized, and the semicone angle was compared with the theoretical Taylor angle. In addition, the ratio of electric normal force and electric tangential force on the charged surface of the Taylor cone was recommended as a parameter that determines the degree of cone-jet stability. The cone-jet became more stable as this ratio got smaller. This approach was a systematic and effective way of obtaining the Taylor cone of the cone-jet mode and evaluating the jetting stability. The control of the inks with optimized experimental parameters by this method will improve the jetting performance in EHD inkjet printing.

  7. Comparison of theoretical and experimental determination of the flexing of scratch drive actuator plates

    NASA Astrophysics Data System (ADS)

    Li, Lijie; Brown, James G.; Uttamchandani, Deepak G.

    2002-09-01

    The scratch drive actuator (SDA) is a key element in microelectromechanical System (MEMS) technology. The actuator can be designed to travel very long distance with precise step size. Various articles describe the characteristics of scratch drive actuators.3, 6, 8 The MEMS designer needs models of SDA in order to incorporate them into their Microsystems applications. The objective of our effort is to develop models for SDA when it is in the working state. In this paper, a suspended SDA plate actuated by electrostatic force is analyzed. A mathematical model is established based on electrostatic coupled mechanical theory. Two phases have been calculated because the plate will contact the bottom surface due to the electrostatic force. One phase is named non-contact mode, and another is named contact mode. From these two models, the relationship between applied voltage and contact distance has been obtained. The geometrical model of bending plate is established to determine the relationship between contact distance and step size. Therefore we can use those two results to obtain the result of step size versus applied voltage that we expect. Finally, couple-field electro-mechanical simulation has been done by commercial software IntelliSuite. We assume that the dimension of SDA plate and bushing are fixed. All the material properties are from JDSU Cronos MUMPs. A Veeco NT1000 surface profiling tool has been used to investigate the bending of SDA plate. The results of experimental and theoretical are compared.

  8. Determining directional emissivity: Numerical estimation and experimental validation by using infrared thermography

    NASA Astrophysics Data System (ADS)

    Peeters, J.; Ribbens, B.; Dirckx, J. J. J.; Steenackers, G.

    2016-07-01

    Little research has examined that inaccurate estimations of directional emissivity form a major challenge during both passive and active thermographic measurements. Especially with the increasing use of complex curved shapes and the growing precision of thermal cameras, these errors limit the accuracy of the thermal measurements. In this work we developed a technique to estimate the directional emissivity using updated numerical simulations. The reradiation on concave surfaces is examined by thermal imaging of a homogeneous heated curved metal and nylon test sample. We used finite element modelling to predict the reradiation of concave structures in order to calculate the parameters of an approximating formula for the emissivity dependent on the angle to the normal vector on each element. The differences between experimental and numerical results of the steel test sample are explained using electron microscopy imaging and the validation on different materials. The results suggest that it is possible to determine the errors of thermal imaging testing of complex shapes using a numerical model.

  9. Experimental determination of partition coefficient for β-pinene ozonolysis products in SOA

    NASA Astrophysics Data System (ADS)

    Gensch, Iulia; Hohaus, Thorsten; Kimmel, Joel; Jayne, John T.; Worsnop, Douglas R.; Kiendler-Scharr, Astrid

    2013-04-01

    In the present study, simultaneous measurement of β-pinene ozonolysis products in the gas phase by Proton Transfer Reaction - Time of Flight Mass Spectrometry (PTR-ToFMS) and particle phase by using an Aerosol Collection Module coupled to a Gas Chromatograph - Mass Spectrometer (ACM-GC-MS) were employed to determine the equilibrium partitioning coefficient (Kp) of several semi-volatile organic species. Mean Kp values of 6.7 10-5 ± 2.5 10-5 for nopinone, 4.8 10-4 ± 1.7 10-4 for apoverbenone, 7.0 10-4 ± 1.7 10-4 for oxonopinone and 1.9 10-3 ± 1.1 10-3 for hydroxynopinone were obtained. The results were compared with calculations arising from studies on the gas-particle partitioning, based on the Pankow absorption model. The experimental partition coefficients are two to three orders of magnitudes higher than the calculated values, leading to the conclusion that the amount of semi-volatile organic compounds in secondary organic aerosol (SOA) is currently underestimated by the theory, thus impacting on the modeling of the organic matter in the atmosphere.

  10. Analytical methods to determine electrochemical factors in electrotaxis setups and their implications for experimental design.

    PubMed

    Schopf, Anika; Boehler, Christian; Asplund, Maria

    2016-06-01

    Direct current (DC) stimulation can be used to influence the orientation and migratory behavior of cells and results in cellular electrotaxis. Experimental work on such phenomena commonly relies on electrochemical dissolution of silver:silver-chloride (Ag:AgCl) electrodes to provide the stimulation via salt bridges. The strong ionic flow can be expected to influence the cell culture environment. In order to shed more light on which effects that must be considered, and possibly counter balanced, we here characterize a typical DC stimulation system. Silver migration speed was determined by stripping voltammetry. pH variability with stimulation was measured by ratiometric image analysis and conductivity alterations were quantified via two electrode impedance spectroscopy. It could be concluded that pH shifts towards more acidic values, in a linear manner with applied charge, after the buffering capability of the culture medium is exceeded. In contrast, the influence on conductivity was of negligible magnitude. Silver ions could enter the culture chamber at low concentrations long before a clear effect on the viability of the cultured cells could be observed. A design rule of 1cm salt bridge per C of stimulation charge transferred was however sufficient to ensure separation between cells and silver at all times.

  11. Theoretical and Experimental Determination of the Proton Affinity of (CF3CH2)2O

    NASA Technical Reports Server (NTRS)

    Zehe, Michael J.; Ball, David W.

    1998-01-01

    We report the experimental determination of the proton affinity of the molecule (CF3CH2)2O using chemical ionization mass spectrometry, and we compare it to the theoretical value obtained for protonation at the oxygen atom using the calculational methodology (MP2/6-31G**//MP2/3-21G). The proton affinity for this molecule as measured by bracketing experiments was between 724 kJ/mole and 741 kJ/mole. Ab initio (MP2/6-31G**//MP2/3-21G) calculations yield a value of about 729 kJ/mole, in agreement with the chemical ionization experiments. The results of these and related calculations suggest that the (MP2/6-31G**//MP2/3-21G) methodology is acceptable for estimating the proton affinities of partially-and fully-fluorinated methyl and ethyl ethers. We submit that any conclusions about the chemistry of fluoroether polymer lubricants based on their basicity can also be predicted reliably with such calculations.

  12. Experimental determination of Representative Volume Element (RVE) size in woven composites

    NASA Astrophysics Data System (ADS)

    Koohbor, Behrad; Ravindran, Suraj; Kidane, Addis

    2017-03-01

    A systematic approach is proposed to estimate the length scales of the representative volume element (RVE) in orthogonal plain woven composites. The approach is based on experimental full-field deformation measurements at mesoscopic scales. Stereovision digital image correlation (DIC) is conducted to determine the full-field strain distribution in on- and off-axis specimens loaded axially in tension. A sensitivity analysis is carried out to optimize the image correlation parameters. Using the optimized set of image correlation parameters, full-field strains are measured and used in conjunction with a simple strain averaging algorithm to identify the length scales at which globally applied and spatially-averaged local strains converge in values. The size of a virtual window containing local strain data, the average of which has the same value as the global strain, is identified as the RVE dimensions for the examined material. The smallest RVE sizes found in this work are shown to be both strain and angle dependent. The largest RVE dimension obtained is reported as a unique, strain and orientation insensitive RVE size for the woven composite examined.

  13. Experimental Determination of the Formation Enthalpy of Calcium Cobaltate from Sol-Gel Precursors

    NASA Astrophysics Data System (ADS)

    Holgate, T. C.; Wu, N.; Nong, N. V.; Pryds, N.

    2017-02-01

    Calcium cobaltate (Ca3Co4O9) remains one of the most promising p-type oxide materials for high-temperature thermoelectric energy conversion. While much progress has been made in refining our understanding of the unique structure of the material, as well as optimization of the transport properties for thermoelectric efficiency, there remains a gap in the knowledge, both experimental and theoretical, of the thermodynamics of the system. Presented herein is an analysis of the heat of formation of the Ca3Co4O9 phase from sol-gel precursors using a highly sensitive differential scanning calorimeter, as well as observations of its decomposition into the Ca3Co2O6 phase. The reaction enthalpy of forming Ca3Co4O9 from CaCO3 and Co3O4 sol-gel precursors was determined to be +284 (±2%) kJ/mol, leading to a standard enthalpy of Ca3Co4O9 of -3307 (±3.5%) kJ/mol.

  14. Determination of the molecular signature of fossil conifers by experimental palaeochemotaxonomy - Part 1: The Araucariaceae family

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Hautevelle, Y.; Michels, R.

    2013-03-01

    Twelve species of the conifer family Araucariaceae, including Araucaria (6 species), Agathis (3 species) and Wollemia (1 species) genera, were submitted to artificial maturation by confined pyrolysis. The aim of these experiments is to transform the biomolecules synthesized by these species into their homologous geomolecules in laboratory conditions. Determination of the diagenetic molecular signatures of Araucariaceae through experimentation on extant representatives allows us to complete our knowledge in botanical palaeochemotaxonomy. Such knowledge is relevant to palaeoenvironmental, environmental and archaeology purposes. All artificially diagenetic species of Araucariaceae are firstly characterized by a predominance of saturated tetracyclic diterpenoids including ent-beyerane, phyllocladanes and ent-kauranes. Moreover, Araucaria genus shows a high relative abundance of bicyclic sesquiterpenoids, particularly the cadalane-type compounds accompanied by those of eudesmane and bisabolane types as well as chamazulene and pentamethyl-dihydroindenes. Diterpenoids are of labdane, isopimarane and abietane types (essentially derived from abietanoic acids) as well as isohexyl alkylaromatic hydrocarbons. Compared to the tetracyclic diterpenoids, these compounds show a relatively lower abundance, reaching trace levels in the case of saturated abietanes. Distributions of sesquiterpenoids and diterpenoids of Agathis show some similarities to that of Araucaria, with the exception of one species, in which the tetracyclic compounds are absent and the abietane type (essentially derived from abietanoic acids) predominant. High similarities between the Wollemia and Araucaria genera are observed. Both are characterized by some high relative abundance of tetracyclic compounds with no predominance of other specific diterpenoids.

  15. Using an experimental manipulation to determine the effectiveness of a stock enhancement program

    USGS Publications Warehouse

    Stewart, David R.; Long, James M.

    2015-01-01

    We used an experimental manipulation to determine the impact of stocking 178 mm channel catfish Ictalurus punctatus in six impoundments. The study design consisted of equal numbers (two) of control, ceased-stock, and stocked treatments that were sampled one year before and two years after stocking. Relative abundance, growth, size structure, and average weight significantly changed over time based on samples collected with hoop nets. Catch rates decreased at both ceased-stock lakes and increased for one stocked lake, while growth rates changed for at least one ceased-stock and stocked lake. The average weight of channel catfish in the ceased-stock treatment increased by 6% and 25%, whereas weight decreased by 28% and 78% in both stocked lakes. The variability in observed responses between lakes in both ceased-stock and stocked treatments indicates that a one-size-fits-all stocking agenda is impractical, suggesting lake specific and density-dependent mechanisms affect channel catfish population dynamics.

  16. Experimental Determination and Thermodynamic Modeling of Electrical Conductivity of SRS Waste Tank Supernate

    SciTech Connect

    Pike, J.; Reboul, S.

    2015-06-01

    SRS High Level Waste Tank Farm personnel rely on conductivity probes for detection of incipient overflow conditions in waste tanks. Minimal information is available concerning the sensitivity that must be achieved such that that liquid detection is assured. Overly sensitive electronics results in numerous nuisance alarms for these safety-related instruments. In order to determine the minimum sensitivity required of the probe, Tank Farm Engineering personnel need adequate conductivity data to improve the existing designs. Little or no measurements of liquid waste conductivity exist; however, the liquid phase of the waste consists of inorganic electrolytes for which the conductivity may be calculated. Savannah River Remediation (SRR) Tank Farm Facility Engineering requested SRNL to determine the conductivity of the supernate resident in SRS waste Tank 40 experimentally as well as computationally. In addition, SRNL was requested to develop a correlation, if possible, that would be generally applicable to liquid waste resident in SRS waste tanks. A waste sample from Tank 40 was analyzed for composition and electrical conductivity as shown in Table 4-6, Table 4-7, and Table 4-9. The conductivity for undiluted Tank 40 sample was 0.087 S/cm. The accuracy of OLI Analyzer™ was determined using available literature data. Overall, 95% of computed estimates of electrical conductivity are within ±15% of literature values for component concentrations from 0 to 15 M and temperatures from 0 to 125 °C. Though the computational results are generally in good agreement with the measured data, a small portion of literature data deviates as much as ±76%. A simplified model was created that can be used readily to estimate electrical conductivity of waste solution in computer spreadsheets. The variability of this simplified approach deviates up to 140% from measured values. Generally, this model can be applied to estimate the conductivity within a factor of two. The comparison of the

  17. Methods for determining the CO2 sorption capacity of coal: Experimental and theoretical high pressure isotherms

    NASA Astrophysics Data System (ADS)

    Weishauptová, Zuzana; Přibyl, Oldřich

    2016-04-01

    One way to reduce CO2 emissions discharged into the atmosphere is by trapping it and storing it in suitable repositories, including coal-bearing strata. The history of coal mining in the Czech Republic is very rich but most of the mines have been closed down in recent years. However, the unmined coal seams are interesting for the purposes of CO2 storage, especially due the opportunities they offer for recovering coal-bed methane. Mine structures of this kind can be found in large parts of the Upper Silesian Basin, where the total storage capacity has been estimated at about 380 Mt CO2. This is an interesting storage potential. In order to identify a suitable high-capacity locality for CO2 storage within a coal seam, it is necessary to study not only the geological conditions within the seam, but also the textural properties of the coal, which control the mechanism and the extent of the storage. The major storage mechanism is by sorption processes that take place in the coal porous system (adsorption in micropores and on the surface of meso/macropores, and absorption in the macromolecular structure). The CO2 sorption capacity is generally indirectly determined in a laboratory by measuring the amount of carbon dioxide captured in a coal sample at a pressure and temperature corresponding to the in situ conditions, using high pressure sorption techniques. The low pressure sorption technique can be used, by setting the partial volumes of CO2 according to its binding and storage mode. The sorption capacity is determined by extrapolation to the saturation pressure as the sum of the individual partially sorbed volumes. The aim of the study was to determine the partial volumes of CO2 bound by different mechanisms in the individual parts of the porous system of the coal, and to compare the sum with the results obtained by the high pressure isotherm. The study was carried out with 3 samples from a borehole survey in the Czech part of the Upper Silesian Basin. A high pressure

  18. Experimental determination of the influence of oxygen on the PRESAGE® dosimeter.

    PubMed

    Alqathami, Mamdooh; Blencowe, Anton; Ibbott, Geoffrey

    2016-01-21

    It is generally accepted that the PRESAGE(®) radiochromic dosimeter is not sensitive to oxygen, however, this claim has not been supported or verified experimentally. Therefore, the aim of this study was to experimentally determine the potential influence of oxygen on dose sensitivity of the PRESAGE(®) dosimeter and its reporting system. Batches of PRESAGE(®) and its radical initiator-leuco dye reporting system were prepared in aerobic and anaerobic conditions. The anaerobic batches were deoxygenated by bubbling nitrogen through the dosimeter precursors or reporting system for 10 min. The dosimeters and reporting systems were prepared in spectrophotometric cuvettes and glass vials, respectively, and were irradiated with 6 MV photons to various radiation doses. Changes in optical density of the dosimeters and reporting system before and after irradiation were measured using a spectrophotometer. The overall results show that oxygen has some influence on the dosimetric characteristics of PRESAGE(®), although the radical initiator does appear to oxidize the leucomalachite green even in the presence of oxygen. Deoxygenation of the reporting system leads to an increase in sensitivity to radiation dose by ~30% when compared to the non-deoxygenated system. A minor increase in sensitivity (~5%) was also achieved by deoxygenating the PRESAGE(®) precursor prior to casting. In addition, dissolved oxygen measurements revealed low levels of dissolved oxygen (0.40 ± 0.04 mg l(-1)) in the polyurethane precursor used to fabricate the PRESAGE(®) dosimeters, as compared to water (8.60 ± 0.03 mg l(-1)) and the reporting system alone (1.30 ± 0.10 mg l(-1)). The results suggest that the presence of oxygen does not inhibit the radiochromic properties of the PRESAGE(®) system. However, deoxygenation of the dosimeter precursors prior to casting improves the dosimeters dose sensitivity by ~5%, which might be particularly useful for measuring low radiation doses. Nevertheless, we

  19. Experimental determination of the influence of oxygen on the PRESAGE® dosimeter

    NASA Astrophysics Data System (ADS)

    Alqathami, Mamdooh; Blencowe, Anton; Ibbott, Geoffrey

    2016-01-01

    It is generally accepted that the PRESAGE® radiochromic dosimeter is not sensitive to oxygen, however, this claim has not been supported or verified experimentally. Therefore, the aim of this study was to experimentally determine the potential influence of oxygen on dose sensitivity of the PRESAGE® dosimeter and its reporting system. Batches of PRESAGE® and its radical initiator-leuco dye reporting system were prepared in aerobic and anaerobic conditions. The anaerobic batches were deoxygenated by bubbling nitrogen through the dosimeter precursors or reporting system for 10 min. The dosimeters and reporting systems were prepared in spectrophotometric cuvettes and glass vials, respectively, and were irradiated with 6 MV photons to various radiation doses. Changes in optical density of the dosimeters and reporting system before and after irradiation were measured using a spectrophotometer. The overall results show that oxygen has some influence on the dosimetric characteristics of PRESAGE®, although the radical initiator does appear to oxidize the leucomalachite green even in the presence of oxygen. Deoxygenation of the reporting system leads to an increase in sensitivity to radiation dose by ~30% when compared to the non-deoxygenated system. A minor increase in sensitivity (~5%) was also achieved by deoxygenating the PRESAGE® precursor prior to casting. In addition, dissolved oxygen measurements revealed low levels of dissolved oxygen (0.40  ±  0.04 mg l-1) in the polyurethane precursor used to fabricate the PRESAGE® dosimeters, as compared to water (8.60  ±  0.03 mg l-1) and the reporting system alone (1.30  ±  0.10 mg l-1). The results suggest that the presence of oxygen does not inhibit the radiochromic properties of the PRESAGE® system. However, deoxygenation of the dosimeter precursors prior to casting improves the dosimeters dose sensitivity by ~5%, which might be particularly useful for measuring low radiation doses

  20. Experimentally determined attenuation and modulus in Earth analogue materials over a wide range of frequency

    NASA Astrophysics Data System (ADS)

    McCarthy, C.; Fujisawa, K.; Takei, Y.; Hiraga, T.

    2009-12-01

    Seismic observations, particularly in areas of active tectonics, show large variations and can be affected by many variables, including temperature, composition, grain size, volatile content and the presence of small quantities of melt or other fluids. The understanding and interpretation of seismic wave dispersion and attenuation data can be significantly enhanced through improved knowledge of material dynamic response at the grain scale (and smaller). The organic binary system borneol-diphenylamine is a suitable analogue of melting in the Earth’s mantle. Not only does the solid phase deform through the same deformation mechanisms (diffusion creep, dislocation creep) observed in geologic materials, but the moderate and controllable dihedral angle (40° at 316 K) exhibited by this system provides an equilibrium melt-geometry very similar to that of the olivine + basalt system [Takei, 2000]. With a eutectic melting temperature (TE = 316 K at ambient pressure) just above room temperature, borneol-diphenylamine provides an attractive chemical analogue to study the properties of solid-melt interaction, obviating the difficulties associated with high-temperature, high-pressure experimentation. We have initiated compression-compression cyclic loading experiments on single phase (borneol; TM = 477 K) and multiphase (borneol-diphenylamine) aggregates. Our newly developed apparatus is able to apply and measure very small stress and strain amplitudes with high accuracy using a piezoelectric actuator and optical displacement meters, respectively. The planned experimental conditions are P = 1 atm, T = 298 - 333 K, strain amplitude <10-5, f = 10-4 - 102 Hz, and melt fraction φ = 0 - 0.1. The combination of low (sub seismic) frequency data obtained from these forced oscillation experiments and high-frequency data (f = 102 - 106) from ultrasonic wave transmission measurements allows us to explore the dissipation and Young’s modulus over a frequency range of some ten decades

  1. Experimental determination of vertical uprooting resistance for grass species used in flume experiments

    NASA Astrophysics Data System (ADS)

    Edmaier, K.; Crouzy, B.; Ennos, R.; Burlando, P.; Perona, P.

    2012-12-01

    Vegetation affects river morphodynamics by contributing to the stabilization of alluvial sediment via the root system. The survival and establishment of riparian pioneer vegetation on river bars and islands is determined by timescales of vegetation growth and flood interarrival times. Several laboratory experiments have investigated the role of vegetation in river morphodynamics but none of those has quantied the forces involved to produce uprooting of growing plants. Thus, parallel analyses on root resistance to uprooting are needed. In this work we investigate the uprooting resistance of young vegetation in laboratory experiments, where we vertically uprooted seedlings of Avena sativa and Medicago sativa. Uprooting force and work were related to the root structure (root length, number of roots, root tortuosity) and environmental conditions (grain size, saturation). We found the uprooting work of both species to follow a power law relation with the total root length which was found to be the main driving factor of the process. In addition, the number of roots was found to increase uprooting work. For similar total root length, the multi-root system of Avena sativa shows greater uprooting resistance in terms of work than the single-root system of Medicago sativa. Less sediment saturation produces higher uprooting forces and favors root breaking. Smaller sediment sizes lead to a higher uprooting resistance than bigger ones. Nevertheless, both saturation and grain size showed minor influence on the uprooting process compared to root characteristics. From measured uprooting forces of Avena sativa grown on sediment with a grain size distribution similar to that used in the flume experiments of Perona et al. (2012) we computed the ensemble probability of Avena sativa being uprooted by a particular drag force at certain growth stages, allowing us to compute a probability distribution of being uprooted in dependence of the root length and thus experimentally assess the

  2. Experimental determination of noble gas, SF6 and CO2 flow profiles through a porous sandstone

    NASA Astrophysics Data System (ADS)

    Kilgallon, Rachel; Gilfillan, Stuart; Edlmann, Katriona; McDermott, Chris

    2016-04-01

    The noble gases (He, Ne, Ar, Kr and Xe) and SF6 have recently been used as artificial and inherent tracers of CO2 flow and migration from within[1,2] and from geological reservoirs[3]. However, outstanding questions remain, particularly regarding the flow behaviour of the noble gases compared to CO2. Here we present results from specially constructed experimental equipment, which has been used to determine the factors affecting transport of noble gases relative to CO2 in a porous sandstone. The experimental setup consists of a sample loop that can be loaded with a desired gas mixture. This sample can be released as a pulse into a feeder gas stream through a flow cell. The flow cell consists of a 3.6 cm diameter core, which can be of any length. The sample is surrounded by aluminium foil and treated with epoxy resin inside stainless steel tubing. The flow cell is encased by two purpose designed dispersion end plates. Real-time analysis of the arrival peaks of the gases downstream is recorded using a Quadrupole Mass Spectrometer (QMS). For the experiments, a 0.96 m core of Fell Sandstone was selected to represent a porous media. Noble gases and SF6 pulses were flowed through a CO2 carrier gas at five different pressure gradients (10 - 50 kPa) with arrival profiles measured using the QMS. Surprisingly, peak arrival times of He were slower than the other noble gases at each pressure gradient. The differences in peak arrival times between He and other noble gases increased as pressure decreased and the curve profiles for each noble gas differ significantly. The heavier noble gases (Kr and Xe) along with SF6 show a steeper peak rise at initial appearance, but have a longer duration profile than the He curves. Interestingly, the breakthrough curve profiles for both Kr and Xe were similar to SF6 indicating that Kr and Xe could be substituted for SF6, which is a potent greenhouse gas, in tracing applications. In addition, CO2 pulses were passed through a N2 carrier gas. The

  3. Deformation mechanisms of antigorite serpentinite at subduction zone conditions determined from experimentally and naturally deformed rocks

    NASA Astrophysics Data System (ADS)

    Auzende, Anne-Line; Escartin, Javier; Walte, Nicolas P.; Guillot, Stéphane; Hirth, Greg; Frost, Daniel J.

    2015-02-01

    We performed deformation-DIA experiments on antigorite serpentinite at pressures of 1-3.5 GPa and temperatures of between 400 and 650 °C, bracketing the stability of antigorite under subduction zone conditions. For each set of pressure-temperature (P-T) conditions, we conducted two runs at strain rates of 5 ×10-5 and 1 ×10-4 s-1. We complemented our study with a sample deformed in a Griggs-type apparatus at 1 GPa and 400 °C (Chernak and Hirth, 2010), and with natural samples from Cuba and the Alps deformed under blueschist/eclogitic conditions. Optical and transmission electron microscopies were used for microstructural characterization and determination of deformation mechanisms. Our observations on experimentally deformed antigorite prior to breakdown show that deformation is dominated by cataclastic flow with observable but minor contribution of plastic deformation (microkinking and (001) gliding mainly expressed by stacking disorder mainly). In contrast, in naturally deformed samples, plastic deformation structures are dominant (stacking disorder, kinking, pressure solution), with minor but also perceptible contribution of brittle deformation. When dehydration occurs in experiments, plasticity increases and is coupled to local embrittlement that we attribute to antigorite dehydration. In dehydrating samples collected in the Alps, embrittlement is also observed suggesting that dehydration may contribute to intermediate-depth seismicity. Our results thus show that semibrittle deformation operates within and above the stability field of antigorite. However, the plastic deformation recorded by naturally deformed samples was likely acquired at low strain rates. We also document that the corrugated structure of antigorite controls the strain accommodation mechanisms under subduction conditions, with preferred inter- and intra-grain cracking along (001) and gliding along both a and b. We also show that antigorite rheology in subduction zones is partly controlled

  4. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  5. Accurate monotone cubic interpolation

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1991-01-01

    Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.

  6. SU-E-T-415: Experimental Determination of the Relative Stopping Power of TRUFILL N-BCA Liquid Embolic System in a Clinical Proton Beam

    SciTech Connect

    Mandapaka, A; Ghebremedhin, A; Patyal, B

    2015-06-15

    Purpose: Patients who undergo n-BCA glue embolization as part of treatment for AVMs are later referred for proton therapy. Knowing the relative stopping power of the glue accurately allows us to perform accurate dose calculations. In this study we experimentally determine the relative stopping power of an n-BCA mixture in a 126 MeV and 149.6 MeV proton beams. Methods: One unit of the TRUFILL™ n-BCA liquid embolic system consists of 1g unit of n-BCA, 1g unit of Tantalum powder and one 10mL vial of Ethiodized oil. The physician mixed 3:1 Ethiodized oil to n-BCA. Five units (20cc) of the n-BCA liquid embolic glue were prepared and placed in a 6cm x 3cm x3cm Lucite container. The container was placed in front of a water tank in the proton beam path. A diamond detector (active volume 0.004mm3) was used to measure distal edge of depth dose of a modulated 126 MeV proton beam collimated using a 3cm brass aperture. The procedure was repeated with a container carrying the same amount of water placed in front of the water tank. The difference in the depth dose measured with glue and with water was used to determine the relative stopping power of the glue. The same determination was done earlier at 149.6 MeV using a different smaller sample (4cc) of n-BCA. Results: The relative stopping power of this particular n-BCA mixture was determined to be 1.06 at both 126 MeV and 149.6 MeV. We are working on obtaining the composition data of the n-BCA glue so we can perform Monte Carlo calculations. Conclusion: Accurate value of the stopping power of the n-BCA glue in the proton beam was determined to be 1.06. It will improve the accuracy of dose calculations in proton radiosurgery procedures on AVM patients with n-BCA embolization.

  7. Rotational barriers of biphenyls having heavy heteroatoms as ortho-substituents: experimental and theoretical determination of steric effects.

    PubMed

    Lunazzi, Lodovico; Mancinelli, Michele; Mazzanti, Andrea; Lepri, Susan; Ruzziconi, Renzo; Schlosser, Manfred

    2012-03-07

    The free energies of activation for the aryl-aryl rotation of 17 biphenyl derivatives, bearing a heavy heteroatom (S, Se, Te, P, Si, Sn) as ortho substituent, have been measured by variable temperature NMR. These numbers, so called B values, represent a meaningful measure of the steric hindrance exerted by the selected substituents. DFT computations match quite satisfactorily the experimental barriers and the ground state geometries as well (determined, in two cases, by X-ray diffraction). The present values extend the available list of B values and thus provide an enlarged basis for the compilation of the space requirements of standard substituents, based solely on experimental determinations.

  8. A hybrid experimental-numerical technique for determining 3D velocity fields from planar 2D PIV data

    NASA Astrophysics Data System (ADS)

    Eden, A.; Sigurdson, M.; Mezić, I.; Meinhart, C. D.

    2016-09-01

    Knowledge of 3D, three component velocity fields is central to the understanding and development of effective microfluidic devices for lab-on-chip mixing applications. In this paper we present a hybrid experimental-numerical method for the generation of 3D flow information from 2D particle image velocimetry (PIV) experimental data and finite element simulations of an alternating current electrothermal (ACET) micromixer. A numerical least-squares optimization algorithm is applied to a theory-based 3D multiphysics simulation in conjunction with 2D PIV data to generate an improved estimation of the steady state velocity field. This 3D velocity field can be used to assess mixing phenomena more accurately than would be possible through simulation alone. Our technique can also be used to estimate uncertain quantities in experimental situations by fitting the gathered field data to a simulated physical model. The optimization algorithm reduced the root-mean-squared difference between the experimental and simulated velocity fields in the target region by more than a factor of 4, resulting in an average error less than 12% of the average velocity magnitude.

  9. 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.

  10. Direct experimental determination of the topological winding number of skyrmions in Cu2OSeO3.

    PubMed

    Zhang, S L; van der Laan, G; Hesjedal, T

    2017-02-24

    The mathematical concept of topology has brought about significant advantages that allow for a fundamental understanding of the underlying physics of a system. In magnetism, the topology of spin order manifests itself in the topological winding number which plays a pivotal role for the determination of the emergent properties of a system. However, the direct experimental determination of the topological winding number of a magnetically ordered system remains elusive. Here, we present a direct relationship between the topological winding number of the spin texture and the polarized resonant X-ray scattering process. This relationship provides a one-to-one correspondence between the measured scattering signal and the winding number. We demonstrate that the exact topological quantities of the skyrmion material Cu2OSeO3 can be directly experimentally determined this way. This technique has the potential to be applicable to a wide range of materials, allowing for a direct determination of their topological properties.

  11. Direct experimental determination of the topological winding number of skyrmions in Cu2OSeO3

    PubMed Central

    Zhang, S. L.; van der Laan, G.; Hesjedal, T.

    2017-01-01

    The mathematical concept of topology has brought about significant advantages that allow for a fundamental understanding of the underlying physics of a system. In magnetism, the topology of spin order manifests itself in the topological winding number which plays a pivotal role for the determination of the emergent properties of a system. However, the direct experimental determination of the topological winding number of a magnetically ordered system remains elusive. Here, we present a direct relationship between the topological winding number of the spin texture and the polarized resonant X-ray scattering process. This relationship provides a one-to-one correspondence between the measured scattering signal and the winding number. We demonstrate that the exact topological quantities of the skyrmion material Cu2OSeO3 can be directly experimentally determined this way. This technique has the potential to be applicable to a wide range of materials, allowing for a direct determination of their topological properties. PMID:28233782

  12. Determination of factors affecting relapse of vaginitis among reproductive-aged women: An experimental study

    PubMed Central

    Parsapour, Roxana; Majlessi, Fereshteh; Rahimiforoushani, Abbas; Sadeghi, Roya

    2017-01-01

    Introduction Vaginitis is a common problem for women, especially in reproductive-aged women. It is a worldwide health problem with many side effects but could be prevented by a health-promoting lifestyle related to vagina health. The aim of this study was to determine the factors affecting relapse of vaginitis. Methods In this experimental study, 350 reproductive-aged women with vaginitis were selected from 10 health centers in Kermanshah (Iran) during 2015 and were equally included in the intervention and control groups. To collect data, a researcher-created questionnaire, which included sociodemographic and health-promoting lifestyle questions, was used. The educational intervention was performed over 20 sessions, each lasting 25–35 minutes. An intervention group was educated by face-to-face education, pamphlets, phone contacts, text messages, and social media. Another group continued the routine clinic education and treatment without contacting the intervention group. Data were analyzed through chi-square and a logistics regression model using IBM-SPSS version 20. Results The results of the study indicated a significant relation between sociodemographic characteristics such as women and their husbands’ literacy, job, family size, income, area for each member of family, tendency of pregnancy, body mass index (BMI), and caesarean experience (p<0.001) and vaginitis. In addition, significant relationships between health-promoting lifestyle dimensions and prevention of vaginitis were identified. Relapse after intervention in the intervention group was 27.7% and 72.3% in the control group. According to the logistic regression analysis, chance for relapse of vaginitis in the group that did not receive intervention was more than the same chance in the intervention group (OR=5.14). Conclusion Health-promoting lifestyle intervention influences prevention of vaginitis. Health-promoting lifestyle, literacy promotion, prevention of caesarian, and obesity are beneficial

  13. Experimental and analytical methods for the determination of connected-pipe ramjet and ducted rocket internal performance

    NASA Astrophysics Data System (ADS)

    1994-07-01

    Connected-pipe, subsonic combustion ramjet and ducted rocket performance determination procedures used by the NATO countries have been reviewed and evaluated. A working document has been produced which provides recommended methods for reporting test results and delineates the parameters that are required to be measured. Explanations and detailed numerical examples are presented covering the determination of both theoretical and experimental performances, the use of air heaters and uncertainty and error analysis.

  14. THE EFFECT OF EXPERIMENTAL ERROR ON THE DETERMINATION OF THE OPTIMUM METAL-CUTTING CONDITIONS.

    DTIC Science & Technology

    the uncertainty in the parameter-estimates of the tool-life equation. The confidence interval for V(min) depends on the magnitude of the cost-time...parameter t sub e; as t sub e increases, the V(min) confidence interval decreases. The confidence interval for V(min) is affected by the experimental...range of feed in tool-life testing; the smallest confidence interval is at the average experimental feed. A decision rule based on the minimax

  15. Experimental and numerical in-plane displacement fields for determine the J-integral on a PMMA cracked specimen

    NASA Astrophysics Data System (ADS)

    Hedan, S.; Valle, V.; Cottron, M.

    2010-06-01

    Contrary to J-integral values calculated from the 2D numerical model, calculated J-integrals [1] in the 3D numerical and 3D experimental cases are not very close with J-integral used in the literature. We can note a problem of structure which allows three-dimensional effects surrounding the crack tip to be seen. The aim of this paper is to determine the zone where the Jintegral formulation of the literature is sufficient to estimate the energy release rate (G) for the 3D cracked structure. For that, a numerical model based on the finite element method and an experimental setup are used. A grid method is adapted to experimentally determine the in-plane displacement fields around a crack tip in a Single-Edge-Notch (SEN) tensile polymer (PMMA) specimen. This indirect method composed of experimental in-plane displacement fields and of 2 theoretical formulations, allows the experimental J-integral on the free-surface to be determined and the results obtaining by the 3D numerical simulations to be confirmed.

  16. A combined analytical and experimental approach to the determination of residual stresses in very thin cylindrical shells

    NASA Astrophysics Data System (ADS)

    Franco, Jamal Eli

    The residual stress in a high alloy ultra thin cylindrical shell is studied. The objective of this research is to quantify and develop an understanding of the residual stress produced during the fabrication process. It is shown, with the application of finite element analysis and experimental measurements, that the residual stress can be predicted and quantified. This dissertation investigates the experimental and numerical methods to determine the residual stress in high alloy ultra thin cylindrical shells. Experimental measurements of the shell profiles are used to obtain stresses during manufacturing. Finite element analysis is used to verify the experimental results. These results compare favorably with theoretical values. This dissertation shows that the thermal process applied to the shell for separation does not contribute to the residual stress. A residual stress due to the bending moment caused by the conical geometry of the shell is evident in the finite element results.

  17. Refined non-steady-state gas-liquid chromatography for accurate determination of limiting activity coefficients of volatile organic compounds in water: application to C(1)-C(5) alkanols.

    PubMed

    Dohnal, Vladimír; Ondo, Daniel

    2005-12-02

    This work presents a new refined method of non-steady-state gas-liquid chromatography (NSGLC) suitable for determination of limiting activity coefficients of VOCs in water. The modifications done to the original NSGLC theory address its elements (as the solvent elution rate from the column) as well as other new aspects. The experimental procedure is modified accordingly, taking advantage of current technical innovations. The refined method is used systematically to determine limiting activity coefficients (Henry's law constants, limiting relative volatilities) of isomeric C(1)-C(5) alkanols in water at 328.15K. Applied to retention data measured in this work the refined NSGLC theory gives values 15-20% higher than those from the original approach. The values obtained by the refined NSGLC method agree very well (typically within 3%) with the most reliable literature data determined by other experimental techniques, this result verifying thus the correct performance of the refined method and demonstrating an improved accuracy of the new results.

  18. Accurately measuring dynamic coefficient of friction in ultraform finishing

    NASA Astrophysics Data System (ADS)

    Briggs, Dennis; Echaves, Samantha; Pidgeon, Brendan; Travis, Nathan; Ellis, Jonathan D.

    2013-09-01

    UltraForm Finishing (UFF) is a deterministic sub-aperture computer numerically controlled grinding and polishing platform designed by OptiPro Systems. UFF is used to grind and polish a variety of optics from simple spherical to fully freeform, and numerous materials from glasses to optical ceramics. The UFF system consists of an abrasive belt around a compliant wheel that rotates and contacts the part to remove material. This work aims to accurately measure the dynamic coefficient of friction (μ), how it changes as a function of belt wear, and how this ultimately affects material removal rates. The coefficient of friction has been examined in terms of contact mechanics and Preston's equation to determine accurate material removal rates. By accurately predicting changes in μ, polishing iterations can be more accurately predicted, reducing the total number of iterations required to meet specifications. We have established an experimental apparatus that can accurately measure μ by measuring triaxial forces during translating loading conditions or while manufacturing the removal spots used to calculate material removal rates. Using this system, we will demonstrate μ measurements for UFF belts during different states of their lifecycle and assess the material removal function from spot diagrams as a function of wear. Ultimately, we will use this system for qualifying belt-wheel-material combinations to develop a spot-morphing model to better predict instantaneous material removal functions.

  19. Experimental determination of heat transfer coefficient in the slip regime and its anomalously low value

    NASA Astrophysics Data System (ADS)

    Demsis, Anwar; Verma, Bhaskar; Prabhu, S. V.; Agrawal, Amit

    2009-07-01

    In this paper, the measurement of the heat transfer coefficient in rarefied gases is presented; these are among the first heat transfer measurements in the slip flow regime. The experimental setup is validated by comparing friction factor in the slip regime and heat transfer coefficient in the continuum regime. Experimental results suggest that the Nusselt number is a function of Reynolds and Knudsen numbers in the slip flow regime. The measured values for Nusselt numbers are smaller than that predicted by theoretical or simulation results, and can become a few orders of magnitude smaller than the theoretical values in the continuum regime. The results are repeatable and expected to be useful for further experimentation and modeling of flow in the slip and transition regimes.

  20. Experimental and theoretical NMR determination of isoniazid and sodium p-sulfonatocalix[n]arenes inclusion complexes.

    PubMed

    de Assis, João V; Teixeira, Milena G; Soares, Cássia G P; Lopes, Juliana F; Carvalho, Guilherme S L; Lourenço, Maria C S; de Almeida, Mauro V; de Almeida, Wagner B; Fernandes, Sergio A

    2012-10-09

    In this work the inclusion complex formation of isoniazid with sodium p-sulfonatocalix[n]arenes is reported aiming to improve the physicochemical and biopharmaceutical properties of isoniazid a first line antibuberculosis drug. The architectures of the complexes were proposed according to NMR data Job plot indicating details on the insertion of the isoniazid in the calix[n]arenes cavities. DFT theoretical NMR calculations were also performed for sodium p-sulfonatocalix[4]arene complex with isoniazid, with various modes of complexation being considered, to provide support for the experimental proposal. A comparison between experimental and theoretical ¹H NMR chemical shifts profiles allowed for the inclusion complex characterization confirming the isoniazid inclusion mode which is preferentially through the hydrazide moiety. The remarkable agreement between experimental and theoretical NMR profiles adds support to their use in the structural characterization of inclusion compounds. Antibacterial activity was evaluated and the results indicated the inclusion complexes as a potential strategy for tuberculosis treatment.

  1. Experimentally Determined Mechanical Properties of, and Models for, the Periodontal Ligament: Critical Review of Current Literature

    PubMed Central

    Fill, Ted S.; Carey, Jason P.; Toogood, Roger W.; Major, Paul W.

    2011-01-01

    Introduction. This review is intended to highlight and discuss discrepancies in the literature of the periodontal ligament's (PDL) mechanical properties and the various experimental approaches used to measure them. Methods. Searches were performed on biomechanical and orthodontic publications (in databases: Compendex, EMBASE, MEDLINE, PubMed, ScienceDirect, and Scopus). Results. The review revealed that significant variations exist, some on the order of six orders of magnitude, in the PDL's elastic constants and mechanical properties. Possible explanations may be attributable to different experimental approaches and assumptions. Conclusions. The discrepancies highlight the need for further research into PDL properties under various clinical and experimental loading conditions. Better understanding of the PDL's biomechanical behavior under physiologic and traumatic loading conditions might enhance the understanding of the PDL's biologic reaction in health and disease. Providing a greater insight into the response of the PDL would be instrumental to orthodontists and engineers for designing more predictable, and therefore more efficacious, orthodontic appliances. PMID:21772924

  2. Relativistic effect on total energies for determination of correlation energies of atoms from their experimental total energies

    NASA Astrophysics Data System (ADS)

    Anno, Tosinobu; Teruya, Hirohide

    1989-10-01

    Relativistic effect Erel upon the total electronic energy of an atom is discussed with particular reference to obtaining the nonrelativistic total energy Eexact from the experimental total energy. Numerical values of this effect obtained by various authors by different nonempirical methods are compared for neutral atoms of rare-gas elements. It is shown that methods either of a Hartree-Fock-type or of a Dirac-Hartree-Fock-type give much the same Erel value for He through Ar. It is pointed out that Erel calculated with Hartree-Fock wave functions is not adequate for use in obtaining Eexact from the experimental total energy and that the Erel value calculated with wave functions including electron correlation should work well, although an actual demonstration can be done only for two-electron systems for lack of data. A semiempirical formula is therefore proposed, which is useful for least-squares fit of experimental total energies of isoelectronic series of atoms to extract nonrelativistic total energies along with the relativistic effect. From nonrelativistic energies thus derived, semiempirical values of correlation energies of atoms are obtained. The results thus obtained are in reasonable agreement with correlation energies derived by Clementi along somewhat different lines. The power series expansion in Z of the fitted formula for the He series shows that numerical values of expansion coefficients agree reasonably well with the corresponding values obtained by accurate relativistic and nonrelativistic Z expansion-type calculations.

  3. Experimental study on determining factors of canopy interception using artificial Christmas trees

    NASA Astrophysics Data System (ADS)

    Murakami, Shigeki; Toba, Tae

    2013-04-01

    Evaporation of canopy interception (CI) is a major component of water balance in forested areas. Theoretically, the evaporation amount is dependent on the tree height, i.e. aerodynamic roughness. Nevertheless, the theory does not always explain the observed results and the observational fact that CI during rainfall is proportional to the rainfall intensity makes the problem paradoxical (Murakami, 2006). The objective of this study is to try to find the determining factors of CI in terms of the stand structure using artificial Christmas trees that is easy to modify the height and tree density. Two kinds of artificial Christmas trees were used: a) 65 cm high with the maximum canopy diameter of 30 cm, and b) 150 cm high with the greatest canopy diameter of 75 cm. We set those trees on three trays and left them outside to measure CI using natural rainfall. Artificial trees a) were set on Tray #1 and #2 measuring 178-cm-square. Artificial trees b) were fixed on Tray #3 with a size of 360-cm-square. Tray #1 was a control and the stand structure was unchanged throughout the experiment, i.e. tree height was 65 cm with 41 stems on the tray. Three experimental runs were conducted; Run #1 and #2 were to compare the effect of stem length (tree height) on CI. Run #3 was to evaluate the effect of thinning. The initial number of trees on each tray was 41 (Run #1 and #2), and it was reduced to 25 after thinning for Tray #2 and #3 (Run #3). At Run #1 tree heights of Tray #2 and #3 were 90 cm and 150 cm (original), respectively, and at Run #2 and #3 they were 120 cm and 240 cm, respectively. In Tray #1 canopy interception rate (IR, the ratio of CI to gross rainfall) was constant (12.1% to 13.3%). IR increased with tree height for each tree, i.e. a) and b). In Tray #2, i.e. tree a), IR increased from 19.7% to 22.8% after thinning, while in Tray #3, i.e. tree b), it diminished from 20.0% to 13.8%. Preliminary analysis showed that hourly CI is clearly proportional to hourly rainfall

  4. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  5. Benchmark calculations with correlated molecular wave functions. V. The determination of accurate [ital ab] [ital initio] intermolecular potentials for He[sub 2], Ne[sub 2], and Ar[sub 2

    SciTech Connect

    Woon, D.E. )

    1994-02-15

    Dimer interactions of helium, neon, and argon have been studied using the augmented correlation consistent basis sets of Dunning and co-workers. Two correlation methods have been employed throughout; Moller--Plesset perturbation theory through fourth-order (MP4) and single and double excitation coupled-cluster theory with perturbative treatment of triple excitations [CCSD(T)]. Full configuration interaction (FCI) calculations were performed on He[sub 2] for some basis sets. In general, only valence electrons were correlated, although some calculations which also correlated the [ital n]=2 shell of Ar[sub 2] were performed. Dimer potential energy curves were determined using the supermolecule method with and without the counterpoise correction. A series of additional basis sets beyond the augmented correlation consistent sets were explored in which the diffuse region of the radial function space has been systematically saturated. In combination with the systematic expansion across angular function space which is inherent to the correlation consistent prescription, this approach guarantees very accurate atomic polarizabilities and hyperpolarizabilities and should lead to an accurate description of dispersion forces. The best counterpoise-corrected MP4 values for the well depths of the three dimers are (in microhartrees, empirical values in parentheses) He[sub 2], 31.9 (34.6); Ne[sub 2], 123 (134); and Ar[sub 2], 430 (454). The corresponding CCSD(T) values are He[sub 2], 33.1; Ne[sub 2], 128; and Ar[sub 2], 417. Although these values are very good, the nearly exponential convergence of well depth as a function of basis quality afforded by using the various series of correlation consistent basis sets allows estimation of complete basis set (CBS) limiting values. The MP4 estimated CBS limits are He[sub 2], 32.2; Ne[sub 2], 126; and Ar[sub 2], 447.

  6. Some Determinants of Public Acceptance of Randomized Control Group Experimental Designs

    ERIC Educational Resources Information Center

    Hillis, Jay W.; Wortman, Camille B.

    1976-01-01

    Subjects read a supposedly real news account of a medical experiment in which the scarcity of the treatment employed and the amount of scientific justification for the experiment were experimentally varied. Factors that might influence public attitudes about social experiments are explored. (Author/DEP)

  7. Experimental determination of neutron lifetimes through macroscopic neutron noise in the IPEN/MB-01 reactor

    NASA Astrophysics Data System (ADS)

    Gonnelli, Eduardo; Diniz, Ricardo

    2013-05-01

    The neutron lifetimes of the core, reflector, and global were experimentally obtained through macroscopic neutron noise in the IPEN/MB-01 reactor for five levels of subcriticality. The theoretical Auto Power Spectral Densities were derived by point kinetic equations taking the reflector effect into account, and one of the approaches consider an additional group of delayed neutrons.

  8. Predicting gaseous reaction rates of short chain chlorinated paraffins with ·OH: overcoming the difficulty in experimental determination.

    PubMed

    Li, Chao; Xie, Hong-Bin; Chen, Jingwen; Yang, Xianhai; Zhang, Yifei; Qiao, Xianliang

    2014-12-02

    Short chain chlorinated paraffins (SCCPs) are under evaluation for inclusion in the Stockholm Convention on persistent organic pollutants. However, information on their reaction rate constants with gaseous ·OH (kOH) is unavailable, limiting the evaluation of their persistence in the atmosphere. Experimental determination of kOH is confined by the unavailability of authentic chemical standards for some SCCP congeners. In this study, we evaluated and selected density functional theory (DFT) methods to predict kOH of SCCPs, by comparing the experimental kOH values of six polychlorinated alkanes (PCAs) with those calculated by the different theoretical methods. We found that the M06-2X/6-311+G(3df,2pd)//B3LYP/6-311 +G(d,p) method is time-effective and can be used to predict kOH of PCAs. Moreover, based on the calculated kOH of nine SCCPs and available experimental kOH values of 22 PCAs with low carbon chain, a quantitative structure-activity relationship (QSAR) model was developed. The molecular structural characteristics determining the ·OH reaction rate were discussed. logkOH was found to negatively correlate with the percentage of chlorine substitutions (Cl%). The DFT calculation method and the QSAR model are important alternatives to the conventional experimental determination of kOH for SCCPs, and are prospective in predicting their persistence in the atmosphere.

  9. A convenient method and numerical tables for sample size determination in longitudinal-experimental research using multilevel models.

    PubMed

    Usami, Satoshi

    2014-12-01

    Recent years have shown increased awareness of the importance of sample size determination in experimental research. Yet effective and convenient methods for sample size determination, especially in longitudinal experimental design, are still under development, and application of power analysis in applied research remains limited. This article presents a convenient method for sample size determination in longitudinal experimental research using a multilevel model. A fundamental idea of this method is transformation of model parameters (level 1 error variance [σ(2)], level 2 error variances [τ 00, τ 11] and its covariance [τ 01, τ 10], and a parameter representing experimental effect [δ]) into indices (reliability of measurement at the first time point [ρ 1], effect size at the last time point [Δ T ], proportion of variance of outcomes between the first and the last time points [k], and level 2 error correlation [r]) that are intuitively understandable and easily specified. To foster more convenient use of power analysis, numerical tables are constructed that refer to ANOVA results to investigate the influence on statistical power by respective indices.

  10. Experimental determination of single-event upset (SEU) as a function of collected charge in bipolar integrated circuits

    NASA Technical Reports Server (NTRS)

    Zoutendyk, J. A.; Malone, C. J.; Smith, L. S.

    1984-01-01

    Single-Event Upset (SEU) in bipolar integrated circuits (ICs) is caused by charge collection from ion tracks in various regions of a bipolar transistor. This paper presents experimental data which have been obtained wherein the range-energy characteristics of heavy ions (Br) have been utilized to determine the cross section for soft-error generation as a function of charge collected from single-particle tracks which penetrate a bipolar static RAM. The results of this work provide a basis for the experimental verification of circuit-simulation SEU modeling in bipolar ICs.

  11. Experimental and numerical determination of the correlation function of level velocities for microwave networks simulating quantum graphs

    NASA Astrophysics Data System (ADS)

    Ławniczak, Michał; Nicolau-Kuklińska, Agata; Hul, Oleh; Masiak, Paweł; Bauch, Szymon; Sirko, Leszek

    2013-03-01

    The parameter-dependent correlation function \\tilde {c}_{\\delta }(\\omega ,\\mathsf {x}) of level velocities is studied experimentally and numerically. The measurements were made for microwave networks simulating quantum graphs. One- and two-port measurements of the scattering matrix \\hat {S} necessary for determining the correlation function \\tilde {c}_{\\delta }(\\omega ,\\mathsf {x}) were realized for the five vertices networks. For the fully connected six vertices network, one-port measurements were made. The obtained experimental and numerical results are compared with the predictions of random matrix theory.

  12. A convenient method for experimental determination of yields and isomeric ratios in photonuclear reactions measured by the activation technique

    NASA Astrophysics Data System (ADS)

    Kolev, D.; Dobreva, E.; Nenov, N.; Todorov, V.

    1995-02-01

    A generalized exact formula is derived for a determination of the experimental isomeric ratio in any incident particle activation. For the particular case, when the activity of the ground state results from the simultaneous decay of both states and can be conveniently measured, the appropriate modification of this formula is evaluated and applied to six photonuclear reactions induced by 43 MeV bremsstrahlung. The experimental isomeric yield ratios of (γ, 3n) 110m,gIn; (γ, p) (γ, pn), (γ, 2n2p) 117m,gIn; (γ, n) 164m,gHo and (γ, 3n) 162m,gHo are deduced.

  13. Experimental Determination of the Dynamic Hydraulic Transfer Function for the J-2X Oxidizer Turbopump. Part One; Methodology

    NASA Technical Reports Server (NTRS)

    Zoladz, Tom; Patel, Sandeep; Lee, Erik; Karon, Dave

    2011-01-01

    An advanced methodology for extracting the hydraulic dynamic pump transfer matrix (Yp) for a cavitating liquid rocket engine turbopump inducer+impeller has been developed. The transfer function is required for integrated vehicle pogo stability analysis as well as optimization of local inducer pumping stability. Laboratory pulsed subscale waterflow test of the J-2X oxygen turbo pump is introduced and our new extraction method applied to the data collected. From accurate measures of pump inlet and discharge perturbational mass flows and pressures, and one-dimensional flow models that represents complete waterflow loop physics, we are able to derive Yp and hence extract the characteristic pump parameters: compliance, pump gain, impedance, mass flow gain. Detailed modeling is necessary to accurately translate instrument plane measurements to the pump inlet and discharge and extract Yp. We present the MSFC Dynamic Lump Parameter Fluid Model Framework and describe critical dynamic component details. We report on fit minimization techniques, cost (fitness) function derivation, and resulting model fits to our experimental data are presented. Comparisons are made to alternate techniques for spatially translating measurement stations to actual pump inlet and discharge.

  14. Experimentally Determined Binding Energies of Astrophysically Relevant Hydrocarbons in Pure and H2O-Layered Ices

    NASA Astrophysics Data System (ADS)

    Behmard, Aida; Graninger, Dawn; Fayolle, Edith; Oberg, Karin I.

    2017-01-01

    Small hydrocarbons represent an important organic reservoir in a variety of interstellar environments. Constraints on desorption temperatures and binding energies of hydrocarbons are thus necessary for accurate predictions of where and in which phase these molecules exist. Through a series of temperature programmed desorption experiments, we determined binding energies of 1, 2, and 3-carbon interstellar hydrocarbons (CH4, C2H2, C2H4, C2H6, C3H4, C3H6, and C3H8) in pure ices and in relation to water ice, the dominant ice constituent during star and planet formation. These empirically determined values can be used to inform observations and models of the molecular spatial distribution in protoplanetary disks, thus providing insight into planetesimal composition. In addition, knowledge of hydrocarbon binding energies will refine simulations of grain surface chemistry, allowing for better predictions of the chemical conditions that lead to the production of complex organic molecules vital for life.

  15. Simple determination of performance of explosives without using any experimental data.

    PubMed

    Keshavarz, Mohammad Hossein

    2005-03-17

    A simple procedure is introduced by which detonation pressure of CaHbNcOd explosives can be predicted from a, b, c, d and calculated gas phase heat of formation of explosives at any loading density without using any assumed detonation products and experimental data. It is shown here that the loading density, simply calculated heat of formation by additivity rule and atomic composition can be integrated into an empirical formula for predicting the detonation pressure of proposed explosives. Calculated detonation pressures by the introduced method for both pure and explosive formulations show good agreement with respect to measured detonation pressure over a wide range of loading density. The deviations are within about experimental errors.

  16. Experimental determination of the Cu-In-Pb ternary phase diagram

    SciTech Connect

    Bolcavage, A.; Kao, C.R.; Chang, Y.A.; Romig, A.D. Jr.

    1993-12-01

    Use of lead-indium solders in microelectronics packaging has increased over the last decade. Increased usage is due to improved properties, such as greater thermo-mechanical fatigue resistance, lower intermetallic formation rates with base metallizations, such as copper, and lower reflow temperatures. However, search of literature reveals no comprehensive studies on phase equilibrium relations between copper metal and lead-indium solder. Our effort involves a combination of experimental data acquisition and computer modeling to obtain the Cu-In-Pb ternary phase diagram. Isotherms and isopleths of interest at low temperatures are achieved by means of differential scanning calorimetry and electron probe microanalysis. Thermodynamic models of these sections served as a guide for efficient experimentation.

  17. Genome-wide experimental determination of barriers to horizontal gene transfer

    SciTech Connect

    Rubin, Edward; Sorek, Rotem; Zhu, Yiwen; Creevey, Christopher J.; Francino, M. Pilar; Bork, Peer; Rubin, Edward M.

    2007-09-24

    Horizontal gene transfer, in which genetic material is transferred from the genome of one organism to another, has been investigated in microbial species mainly through computational sequence analyses. To address the lack of experimental data, we studied the attempted movement of 246,045 genes from 79 prokaryotic genomes into E. coli and identified genes that consistently fail to transfer. We studied the mechanisms underlying transfer inhibition by placing coding regions from different species under the control of inducible promoters. Their toxicity to the host inhibited transfer regardless of the species of origin and our data suggest that increased gene dosage and associated increased expression is a predominant cause for transfer failure. While these experimental studies examined transfer solely into E. coli, a computational analysis of gene transfer rates across available bacterial and archaeal genomes indicates that the barriers observed in our study are general across the tree of life.

  18. An Experimental Approach to Determine the Flight Dynamics of NASA’s Mars Science Lab Capsule

    DTIC Science & Technology

    2014-01-01

    20 Figure 25. 178-mm HARP gun and experimental setup...and ARL worked together to develop an instrumented model to be fired from the 178-mm-diameter (7-in) High Altitude Research Project ( HARP ) gun. The...maximum diameter was 178 mm with the sabot included, but the actual subscale model diameter was 171 mm. The 178-mm gun was built for HARP , which

  19. The determination of resonance energy in conjugated benzenoids: A combined experimental and theoretical approach

    NASA Astrophysics Data System (ADS)

    Schmalz, Thomas G.

    2016-08-01

    The conjugated circuits model of aromaticity in benzenoids is reconsidered. Values for the parameters R1, R2, and R3 are rederived from experimental enthalpies of formation. It is shown that the value of R3 depends on the shape as well as the size of a 14-cycle. R3 values are found to obey the relation R3pyrene > R3anthracene > R3phenanthrene.

  20. Heterogeneous Blood-Tumor Barrier Permeability Determines Drug Efficacy in Experimental Brain Metastases of Breast Cancer

    PubMed Central

    Lockman, Paul R.; Mittapalli, Rajendar K.; Taskar, Kunal S.; Rudraraju, Vinay; Gril, Brunilde; Bohn, Kaci A.; Adkins, Chris E.; Roberts, Amanda; Thorsheim, Helen R.; Gaasch, Julie A.; Huang, Suyun; Palmieri, Diane; Steeg, Patricia S.; Smith, Quentin R.

    2010-01-01

    Purpose Brain metastases of breast cancer appear to be increasing in incidence, confer significant morbidity, and threaten to compromise gains made in systemic chemotherapy. The blood-tumor barrier (BTB) is compromised in many brain metastases, however, the extent to which this influences chemotherapeutic delivery and efficacy is unknown. Herein, we answer this question by measuring BTB passive integrity, chemotherapeutic drug uptake, and anticancer efficacy in vivo in two breast cancer models that metastasize preferentially to brain. Experimental Design Experimental brain metastasis drug uptake and BTB permeability were simultaneously measured using novel fluorescent and phosphorescent imaging techniques in immune compromised mice. Drug-induced apoptosis and vascular characteristics were assessed using immunofluorescent microscopy. Results Analysis of >2000 brain metastases from two models (human 231-BR-Her2 and murine 4T1-BR5) demonstrated partial BTB permeability compromise in >89% lesions, varying in magnitude within and between metastases. Brain metastasis uptake of 14C- paclitaxel and 14C- doxorubicin was generally greater than normal brain but <15% of that of other tissues or peripheral metastases, and only reached cytotoxic concentrations in a small subset (~10%) of the most permeable metastases. Neither drug significantly decreased the experimental brain metastatic ability of 231-BR-Her2 tumor cells. BTB permeability was associated with vascular remodeling and correlated with over expression of the pericyte protein, desmin. Conclusions This work demonstrates that the BTB remains a significant impediment to standard chemotherapeutic delivery and efficacy in experimental brain metastases of breast cancer. New brain permeable drugs will be needed. Evidence is presented for vascular remodeling in BTB permeability alterations. PMID:20829328

  1. DETECTORS AND EXPERIMENTAL METHODS: Decay vertex reconstruction and 3-dimensional lifetime determination at BESIII

    NASA Astrophysics Data System (ADS)

    Xu, Min; He, Kang-Lin; Zhang, Zi-Ping; Wang, Yi-Fang; Bian, Jian-Ming; Cao, Guo-Fu; Cao, Xue-Xiang; Chen, Shen-Jian; Deng, Zi-Yan; Fu, Cheng-Dong; Gao, Yuan-Ning; Han, Lei; Han, Shao-Qing; He, Miao; Hu, Ji-Feng; Hu, Xiao-Wei; Huang, Bin; Huang, Xing-Tao; Jia, Lu-Kui; Ji, Xiao-Bin; Li, Hai-Bo; Li, Wei-Dong; Liang, Yu-Tie; Liu, Chun-Xiu; Liu, Huai-Min; Liu, Ying; Liu, Yong; Luo, Tao; Lü, Qi-Wen; Ma, Qiu-Mei; Ma, Xiang; Mao, Ya-Jun; Mao, Ze-Pu; Mo, Xiao-Hu; Ning, Fei-Peng; Ping, Rong-Gang; Qiu, Jin-Fa; Song, Wen-Bo; Sun, Sheng-Sen; Sun, Xiao-Dong; Sun, Yong-Zhao; Tian, Hao-Lai; Wang, Ji-Ke; Wang, Liang-Liang; Wen, Shuo-Pin; Wu, Ling-Hui; Wu, Zhi; Xie, Yu-Guang; Yan, Jie; Yan, Liang; Yao, Jian; Yuan, Chang-Zheng; Yuan, Ye; Zhang, Chang-Chun; Zhang, Jian-Yong; Zhang, Lei; Zhang, Xue-Yao; Zhang, Yao; Zheng, Yang-Heng; Zhu, Yong-Sheng; Zou, Jia-Heng

    2009-06-01

    This paper focuses mainly on the vertex reconstruction of resonance particles with a relatively long lifetime such as K0S, Λ, as well as on lifetime measurements using a 3-dimensional fit. The kinematic constraints between the production and decay vertices and the decay vertex fitting algorithm based on the least squares method are both presented. Reconstruction efficiencies including experimental resolutions are discussed. The results and systematic errors are calculated based on a Monte Carlo simulation.

  2. Computational and experimental determinations of the UV adsorption of polyvinylsilsesquioxane-silica and titanium dioxide hybrids.

    PubMed

    Wang, Haiyan; Lin, Derong; Wang, Di; Hu, Lijiang; Huang, Yudong; Liu, Li; Loy, Douglas A

    2014-01-01

    Sunscreens that absorb UV light without photodegradation could reduce skin cancer. Polyvinyl silsesquioxanes are known to have greater thermal and photochemical stability than organic compounds, such as those in sunscreens. This paper evaluates the UV transparency of vinyl silsesquioxanes (VS) and its hybrids with SiO2(VSTE) and TiO2(VSTT) experimentally and computationally. Based on films of VS prepared by sol-gel polymerization, using benzoyl peroxide as an initiator, vinyltrimethoxysilane (VMS) formulated oligomer through thermal curing. Similarly, VSTE films were prepared from VMS and 5-25 wt-% tetraethoxysilane (TEOS) and VSTT films were prepared from VMS and 5-25 wt-% titanium tetrabutoxide (TTB). Experimental average transparencies of the modified films were found to be about 9-14% between 280-320 nm, 67-73% between 320-350nm, and 86-89% between 350-400nm. Computation of the band gap was absorption edges for the hybrids in excellent agreement with experimental data. VS, VSTE and VSTT showed good absorption in UV-C and UV-B range, but absorbed virtually no UV-A. Addition of SiO2 or TiO2 does not improve UV-B absorption, but on the opposite increases transparency of thin films to UV. This increase was validated with molecular simulations. Results show computational design can predict better sunscreens and reduce the effort of creating sunscreens that are capable of absorbing more UV-B and UV-A.

  3. An experimental approach for the determination of axial and flexural wavenumbers in circular exponentially tapered bars

    NASA Astrophysics Data System (ADS)

    Kalkowski, Michał K.; Muggleton, Jen M.; Rustighi, Emiliano

    2017-03-01

    Whilst the dynamics of tapered structures have been extensively studied numerically and analytically, very few experimental results have been presented to date. The main aim of this paper is to derive and demonstrate an experimental method enabling both axial and flexural wavenumbers in exponentially tapered bars to be estimated. Our particular interest in this type of tapering is motivated by its occurrence in naturally grown structures such as tree roots, with an outlook towards remote root mapping. Decomposing a dynamic response into a sum of contributing waves, we propose a method in which two independent wavenumbers can be calculated from five equispaced measurements. The approach was demonstrated in an experiment on a freely suspended wooden specimen supported by theoretical modelling. For axial waves we used the well-established elementary rod theory, whereas for flexural waves we build a piecewise uniform model based on the Timoshenko beam theory. The estimates calculated from the experimental data were compared with the analytical and numerical results and showed good agreement. The limitations of the method include an appropriate choice of sensor spacing, the effect of sensor misalignments and the assumption of small wavenumber variation for flexural waves.

  4. Experimental determination and thermodynamic modeling of the Ni-Re binary system

    SciTech Connect

    Yaqoob, Khurram; Joubert, Jean-Marc

    2012-12-15

    The phase diagram of the Ni-Re binary system has been partially reinvestigated by chemical, structural and thermal characterization of the arc melted alloys. The experimental results obtained during the present investigation were combined with the literature data and a new phase diagram of the Ni-Re binary system is proposed. In comparison with the Ni-Re phase diagram proposed by Nash et al. in 1985 [1], significant differences in the homogeneity domains, freezing ranges and peritectic reaction temperature were evidenced. On the other hand, thermodynamic modeling of the studied system by using the new experimental information has also been carried out with the help of the CALPHAD method. The calculated Ni-Re phase diagram showed a good agreement with the selected experimental information. - Graphical abstract: Ni-Re phase diagram according to the present study. Highlights: Black-Right-Pointing-Pointer Re-investigation of the Ni-Re phase diagram. Black-Right-Pointing-Pointer Extended phase field of the hcp phase. Black-Right-Pointing-Pointer Different freezing ranges and peritectic reaction temperature. Black-Right-Pointing-Pointer Thermodynamic modeling of the studied system by using the CALPHAD method.

  5. The Experimental Determination of Thermal Neutron Flux in the Radiochemistry Curriculum

    ERIC Educational Resources Information Center

    Grant, Patrick M.

    1977-01-01

    Describes an experiment for determining the thermal neutron flux of the light-water nuclear reactor at the University of California, Irvine. The difficulty of the activity can be varied to match the student's level of proficiency. (SL)

  6. Experimental determination of the principal moments of inertia of the Helios prototype spacecraft

    NASA Technical Reports Server (NTRS)

    Gayman, W. H.; Liechti, K.

    1974-01-01

    The moment of inertia of the Helios Spacecraft about its spin axis was determined by use of a roll-fixture using two sets of crossed flexure pivots as elastic constraints. The test procedure entailed measurement of a system oscillation period with each of a set of added moment-of-inertia increments. The tare effect of the fixture was determined by a like process and was subtracted from the gross value to yield the spacecraft roll moment of inertia to an estimated accuracy of 0.2%. Lateral moments of inertia (i.e., about each of three axes normal to the spin axis) were determined by a gravity pendulum method that makes use of the fact that any physical pendulum has a minimum period of oscillation determined by a particular distance from the axis of rotation to the system center of gravity.

  7. The experimental determination of the luminous flux emitted by a few types of lighting sources

    NASA Astrophysics Data System (ADS)

    Spunei, E.; Piroi, I.; Chioncel, C. P.

    2017-01-01

    This paper aims to determine the luminous flux of several types of power sources used for the artificial lighting inside. The luminous flux was determined using a photometer integrator (lumenmeter Ulbricht) and a luxmeter from the laboratory of Electrical and Lighting University “Eftimie Murgu” Resita. Based on a reference source, the constant of the integrator photometer k was determined. The paper presents the measuring results of the luminous flux on several lighting sources: with incandescent, fluorescent, and LED. It has been found that the amount of luminous flux in the nominal data written in the box of lighting sources, does not correspond to the actual measured value. Using the photometric sphere, the actual light output from various sources were it is not known, can be determined.

  8. Experimental determination of Grunieisen gamma for two dissimilar materials (PEEK and Al 5083) via the shock-reverberation technique

    NASA Astrophysics Data System (ADS)

    Roberts, Andrew; Appleby-Thomas, Gareth; Hazell, Paul

    2011-06-01

    Following multiple loading events the resultant shock state of a material will lie away from the principle Hugoniot. Prediction of such states requires knowledge of a materials equation-of-state. The material-specific variable Grunieisen gamma (Γ) defines the shape of ``off-Hugoniot'' points in energy-volume-pressure space. Experimentally the shock-reverberation technique (based on the principle of impedance-matching) has previously allowed estimation of the first-order Grunieisen gamma term (Γ1) for a silicone elastomer. Here, this approach was employed to calculate Γ1 for two dissimilar materials, Polyether ether ketone (PEEK) and the armour-grade aluminium alloy 5083 (H32); thereby allowing discussion of limitations of this technique in the context of plate-impact experiments employing Manganin stress gauges. Finally, the experimentally determined values for Γ1 were further refined by comparison between experimental records and numerical simulations carried out using the commercial code ANYSYS Autodyn®.

  9. Accurate molecular structure and spectroscopic properties for nucleobases: A combined computational - microwave investigation of 2-thiouracil as a case study

    PubMed Central

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2015-01-01

    The computational composite scheme purposely set up for accurately describing the electronic structure and spectroscopic properties of small biomolecules has been applied to the first study of the rotational spectrum of 2-thiouracil. The experimental investigation was made possible thanks to the combination of the laser ablation technique with Fourier Transform Microwave spectrometers. The joint experimental – computational study allowed us to determine accurate molecular structure and spectroscopic properties for the title molecule, but more important, it demonstrates a reliable approach for the accurate investigation of isolated small biomolecules. PMID:24002739

  10. Average elastic and strength characteristics of a honeycomb core and a theoretical-experimental method of their determination

    NASA Astrophysics Data System (ADS)

    Paimushin, V. N.; Zakirov, I. M.; Lukankin, S. A.; Zakirov, I. I.; Kholmogorov, S. A.

    2012-11-01

    To determine the average elastic and strength characteristics of a honeycomb core of hexahedral structure made of a "NOMEX" polymeric paper, tests of special specimens in compression and shear in two mutually perpendicular planes were conducted. Proceeding from the experimental and computational-experimental data found, the dimensionless correcting parameters entering into solutions derived previously in the form of analytical formulas and meant to determine the honeycomb core characteristics mentioned are identified. It is established that, in compression, the average elastic and strength characteristics of the filler considered are practically formed only at the expense of two walls glued together, but in shear in the plane of the walls — at the expense of all four walls of the cell of periodicity.

  11. Experimental validation of optimum input polarization states for Mueller matrix determination with a dual photoelastic modulator polarimeter.

    PubMed

    Gribble, Adam; Layden, David; Vitkin, I Alex

    2013-12-15

    Dual photoelastic modulator polarimeters can measure light polarization, which is often described as a Stokes vector. By evaluating changes in polarization when light interacts with a sample, the sample Mueller matrix also can be derived, completely describing its interaction with polarized light. The choice of which and how many input Stokes vectors to use for sample investigation is under the experimenter's control. Previous work has predicted that sets of input Stokes vectors forming the vertices of platonic solids on the Poincaré sphere allow for the most robust Mueller matrix determination. Further, when errors specific to the dual photoelastic modulator polarimeter are considered, simulations revealed that one specific shape and orientation of Stokes vectors (cube on the Poincaré sphere with vertices away from principal sphere axes) allows for the most robust Mueller matrix determination. Here we experimentally validate the optimum input Stokes vectors for dual photoelastic modulator Mueller polarimetry, toward developing a robust polarimetric platform of increasing relevance to biophotonics.

  12. C-Phycocyanin inhibits 2-acetylaminofluorene-induced expression of MDR1 in mouse macrophage cells: ROS mediated pathway determined via combination of experimental and In silico analysis.

    PubMed

    Roy, Karnati R; Arunasree, Kalle M; Dhoot, Amit; Aparna, Rachamallu; Reddy, Gorla Venkateswara; Vali, Shireen; Reddanna, Pallu

    2007-03-15

    We studied the effects of C-Phycocyanin (C-PC), a biliprotein from Spirulina platensis on the 2-acetylaminofluorene (2-AAF)-induced expression of MDR1, encoded by the multidrug resistance (MDR1) gene, in mouse macrophage cell line (RAW 264.7). Our experimental and In silico studies revealed a significant inhibition of 2-AAF-induced expression of MDR1 protein in C-PC treated mouse macrophage cell line. MDR1 induction by 2-AAF was dependent on ROS (reactive oxygen species)-Akt (protein kinase B)-NF-kappaB (Nuclear factor kappa B) signaling pathway. Generation of ROS, phosphorylation of Akt and corresponding nuclear translocation of NF-kappaB, the events that play a major role in the induction of MDR1 expression, were decreased significantly in C-PC treated cells. NADPH oxidase inhibitor, DPI (Diphenyl iodide), and pharmacological inhibitor of Akt, Akt inhibitor IV, also showed a reduction in MDR1 expression, although not to the same extent as C-PC mediated inhibition of MDR1 expression. To further understand the mechanism, we created a computational model of the detailed ROS-Akt-NF-kappaB pathway. C-PC was modeled purely as a ROS scavenger and this representation matched the experimental trends accurately. Also the ROS levels determined through In silico investigation showed that C-PC was more effective in reduction of MDR1 expression than inhibitors of NADPH oxidase and Akt. Our experimental and In silico studies collectively suggest that 2-AAF induces MDR1 by ROS dependent pathway and C-PC is a potential negative regulator of MDR1 expression. This down regulation of MDR1 expression, induced by xenobiotics such as 2-AAF, suggests C-PC's usefulness in overcoming the drug resistance in cellular systems.

  13. Accurate spectral color measurements

    NASA Astrophysics Data System (ADS)

    Hiltunen, Jouni; Jaeaeskelaeinen, Timo; Parkkinen, Jussi P. S.

    1999-08-01

    Surface color measurement is of importance in a very wide range of industrial applications including paint, paper, printing, photography, textiles, plastics and so on. For a demanding color measurements spectral approach is often needed. One can measure a color spectrum with a spectrophotometer using calibrated standard samples as a reference. Because it is impossible to define absolute color values of a sample, we always work with approximations. The human eye can perceive color difference as small as 0.5 CIELAB units and thus distinguish millions of colors. This 0.5 unit difference should be a goal for the precise color measurements. This limit is not a problem if we only want to measure the color difference of two samples, but if we want to know in a same time exact color coordinate values accuracy problems arise. The values of two instruments can be astonishingly different. The accuracy of the instrument used in color measurement may depend on various errors such as photometric non-linearity, wavelength error, integrating sphere dark level error, integrating sphere error in both specular included and specular excluded modes. Thus the correction formulas should be used to get more accurate results. Another question is how many channels i.e. wavelengths we are using to measure a spectrum. It is obvious that the sampling interval should be short to get more precise results. Furthermore, the result we get is always compromise of measuring time, conditions and cost. Sometimes we have to use portable syste or the shape and the size of samples makes it impossible to use sensitive equipment. In this study a small set of calibrated color tiles measured with the Perkin Elmer Lamda 18 and the Minolta CM-2002 spectrophotometers are compared. In the paper we explain the typical error sources of spectral color measurements, and show which are the accuracy demands a good colorimeter should have.

  14. [Experimental determination of radiation scattering and absorption coefficients in a homogeneous layer of highly-dispersive biological medium].

    PubMed

    Danilov, A A; Masloboev, Iu P; Selishchev, S V; Tereshchenko, S A

    2006-01-01

    A method for experimental determination of optical characteristics of a highly-dispersive medium (radiation scattering and absorption coefficients) is described. The method is based on two mathematical models of ultrashort laser pulse propagation through a highly-dispersive medium (HDM), an axial model and a diffusion model. Milk dissolved in water was used as HDM. Dependences of optical characteristics of HDM on the concentration of milk in water are obtained. The limits of applicability of the axial and diffusion models to media with different scattering and absorption characteristics are determined.

  15. A rapid, accurate and sensitive method with the new stable isotopic tags based on microwave-assisted dispersive liquid-liquid microextraction and its application to the determination of hydroxyl UV filters in environmental water samples.

    PubMed

    Li, Xiu; Chen, Guang; Liu, Jianjun; Liu, Yuxia; Zhao, Xianen; Cao, Ziping; Xia, Lian; Li, Guoliang; Sun, Zhiwei; Zhang, Shijuan; Wang, Hua; You, Jinmao

    2017-05-15

    A rapid, accurate and sensitive method, using the stable isotope labeling (SIL), microwave-assisted dispersive liquid-liquid micro extraction (MADLLME) and the ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), was developed and validated for the determination of hydroxyl UV Filters in environmental water samples. A pair of new isotopic tags D0-/D3-1-methylindole-3-acetic acid (D0-/D3-MIAA) is synthesized, with which a simple yet efficient pretreatment MADLLME-SIL is developed. Under the optimized conditions (80℃, 240W, 180s), the sample pretreatment including analyte extraction, pre-concentration and isotope labeling can be finished conveniently in only 9min. D0-/D3-MIAA labeling improves the chromatographic retention by strengthening the hydrophobicity and enhances the MS response for 3-4 orders of magnitude. Excellent linearity is established by the H/D ratios of 1/10-10/1 with the correlation coefficients >0.9990. The quite low detection limits (0.54-1.79ng/L) are achieved, ensuring the trace detection. This method is successfully applied to a series of environmental water samples. The recoveries (93.2%~103.5%) are significantly improved and the analysis time is largely reduced (<15min). The excellent sensitivity, accuracy, recovery, and efficiency demonstrate this MADLLME-SIL-LC-MS/MS method a superior alternative for the analysis of UV filters in water samples.

  16. Importance of the accuracy of experimental data in the nonlinear chromatographic determination of adsorption energy distributions

    SciTech Connect

    Stanley, B.J.; Guiochon, G. Oak Ridge National Lab., TN )

    1994-11-01

    Adsorption energy distributions (AEDs) are calculated from the classical, fundamental integral equation of adsorption using adsorption isotherms and the expectation-maximization method of parameter estimation. The adsorption isotherms are calculated from nonlinear elution profiles obtained from gas chromatographic data using the characteristic points method of finite concentration chromatography. Porous layer open tubular capillary columns are used to support the adsorbent. The performance of these columns is compared to that of packed columns in terms of their ability to supply accurate isotherm data and AEDs. The effect of the finite column efficiency and the limited loading factor on the accuracy of the estimated energy distributions is presented. This accuracy decreases with decreasing efficiency, and approximately 5000 theoretical plates are needed when the loading factor, L[sub f], equals 0.56 for sampling of a unimodal Gaussian distribution. Increasing L[sub f] further increases the contribution of finite efficiency to the AED and causes a divergence at the low-energy endpoint if too high. This occurs as the retention time approaches the holdup time. Data are presented for diethyl ether adsorption on porous silica and its C-18-bonded derivative. 36 refs., 8 figs., 2 tabs.

  17. Experimental determination of the rotor dynamic coefficients of a gas-lubricated foil journal bearing

    NASA Astrophysics Data System (ADS)

    Hurley, Keith Alan

    1998-12-01

    This thesis describes an experimental investigation of the dynamic stiffness and damping characteristics of an air lubricated leaf-type foil journal bearing. A test bed with dynamic force and response measurement capabilities has been designed and fabricated as a part of the research effort. The test bed consists of a two inch diameter rotor which is supported on two hydrostatic air bearings. The test bearing is centered on the test rotor. The test bed has rotor speed capability of up to 30,000 rpm. Transverse static and dynamic loads of up to 100 lbs can be applied to the test bearing. Direct and cross-coupled transverse stiffness and damping coefficients for a two inch diameter by two inch long eight-leaf foil bearing are obtained using a frequency domain estimation algorithm. Foil bearing dynamic coefficient data is presented for a range of average bearing loads, rotor speeds, and whirl frequency ratios. Experimental predictions of dynamic coefficients for a plain rigid test bearing have been obtained for test bed validation purposes. These experimental results are shown to be in good agreement with corresponding theoretical predictions of rigid bearing dynamic coefficients obtained using a linearized perturbation analysis method. Simulated data has been used to investigate the effects of sensor calibration error and quantization error on the prediction of dynamic coefficients. The results of these investigations are also presented. A rotordynamic analysis is also presented and demonstrates how the dynamic coefficient data can be used to obtain a quantitative assessment of rotor/bearing system stability and frequency response characteristics. Dynamic response characteristics for rigid and compliant surface bearings are compared. The results substantiate the notion that foil bearings have enhanced dynamic performance characteristics in comparison to their rigid bearing counterparts.

  18. Experimental verification of a computational technique for determining ground reactions in human bipedal stance.

    PubMed

    Audu, Musa L; Kirsch, Robert F; Triolo, Ronald J

    2007-01-01

    We have developed a three-dimensional (3D) biomechanical model of human standing that enables us to study the mechanisms of posture and balance simultaneously in various directions in space. Since the two feet are on the ground, the system defines a kinematically closed-chain which has redundancy problems that cannot be resolved using the laws of mechanics alone. We have developed a computational (optimization) technique that avoids the problems with the closed-chain formulation thus giving users of such models the ability to make predictions of joint moments, and potentially, muscle activations using more sophisticated musculoskeletal models. This paper describes the experimental verification of the computational technique that is used to estimate the ground reaction vector acting on an unconstrained foot while the other foot is attached to the ground, thus allowing human bipedal standing to be analyzed as an open-chain system. The computational approach was verified in terms of its ability to predict lower extremity joint moments derived from inverse dynamic simulations performed on data acquired from four able-bodied volunteers standing in various postures on force platforms. Sensitivity analyses performed with model simulations indicated which ground reaction force (GRF) and center of pressure (COP) components were most critical for providing better estimates of the joint moments. Overall, the joint moments predicted by the optimization approach are strongly correlated with the joint moments computed using the experimentally measured GRF and COP (0.78 < or = r(2) < or = 0.99,median,0.96) with a best-fit that was not statistically different from a straight line with unity slope (experimental=computational results) for postures of the four subjects examined. These results indicate that this model-based technique can be relied upon to predict reasonable and consistent estimates of the joint moments using the predicted GRF and COP for most standing postures.

  19. A combined experimental-numerical approach for determining mechanical properties of aluminum subjects to nanoindentation

    PubMed Central

    Liu, Mao; Lu, Cheng; Tieu, Kiet Anh; Peng, Ching-Tun; Kong, Charlie

    2015-01-01

    A crystal plasticity finite element method (CPFEM) model has been developed to investigate the mechanical properties and micro-texture evolution of single-crystal aluminum induced by a sharp Berkovich indenter. The load-displacement curves, pile-up patterns and lattice rotation angles from simulation are consistent with the experimental results. The pile-up phenomenon and lattice rotation have been discussed based on the theory of crystal plasticity. In addition, a polycrystal tensile CPFEM model has been established to explore the relationship between indentation hardness and yield stress. The elastic constraint factor C is slightly larger than conventional value 3 due to the strain hardening. PMID:26464128

  20. Analytical and experimental procedures for determining propagation characteristics of millimeter-wave gallium arsenide microstrip lines

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    1989-01-01

    In this report, a thorough analytical procedure is developed for evaluating the frequency-dependent loss characteristics and effective permittivity of microstrip lines. The technique is based on the measured reflection coefficient of microstrip resonator pairs. Experimental data, including quality factor Q, effective relative permittivity, and fringing for 50-omega lines on gallium arsenide (GaAs) from 26.5 to 40.0 GHz are presented. The effects of an imperfect open circuit, coupling losses, and loading of the resonant frequency are considered. A cosine-tapered ridge-guide text fixture is described. It was found to be well suited to the device characterization.

  1. Experimental determination of magnetohydrodynamic seawater thruster performance in a two Tesla test facility

    SciTech Connect

    Picologlou, B.; Doss, E.; Black, D.; Sikes, W.C.

    1992-09-01

    A two Tesla test facility was designed, built, and operated to investigate the performance of magnetohydrodynamic (MHD) seawater thrusters. The results of this investigation are used to validate MHD thruster performance computer models. The facility test loop, its components, and their design are presented in detail. Additionally, the test matrix and its rational are discussed. finally, representative experimental results of the test program are presented, and are compared to pretest computer model predictions. Good agreement between predicted and measured data has served to validate the thruster performance computer models.

  2. Experimental determination of magnetohydrodynamic seawater thruster performance in a two Tesla test facility

    SciTech Connect

    Picologlou, B.; Doss, E.; Black, D. ); Sikes, W.C. )

    1992-01-01

    A two Tesla test facility was designed, built, and operated to investigate the performance of magnetohydrodynamic (MHD) seawater thrusters. The results of this investigation are used to validate MHD thruster performance computer models. The facility test loop, its components, and their design are presented in detail. Additionally, the test matrix and its rational are discussed. finally, representative experimental results of the test program are presented, and are compared to pretest computer model predictions. Good agreement between predicted and measured data has served to validate the thruster performance computer models.

  3. Parallel Processing Response Times and Experimental Determination of the Stopping Rule

    PubMed

    Townsend; Colonius

    1997-12-01

    It was formerly demonstrated that virtually all reasonable exhaustive serial models, and a more constrained set of exhaustive parallel models, cannot predict critical effects associated with self-terminating models. The present investigation greatly generalizes the parallel class of models covered by similar "impossibility" theorems. Specifically, we prove that if an exhaustive parallel model is not super capacity, and if targets are processed at least as fast as non-targets, then it cannot predict such (self-terminating) effects. Such effects are ubiquitous in the experimental literature, offering strong confirmation for self-terminating processing. Copyright 1997 Academic Press. Copyright 1997 Academic Press

  4. Experimental determination of magnetohydrodynamic seawater thruster performance in a two Tesla test facility

    NASA Astrophysics Data System (ADS)

    Picologlou, B.; Doss, E.; Black, D.; Sikes, W. C.

    1992-08-01

    A two Tesla test facility was designed, built, and operated to investigate the performance of magnetohydrodynamic (MHD) seawater thrusters. The results of this investigation are used to validate MHD thruster performance computer models. The facility test loop, its components, and their design are presented in detail. Additionally, the test matrix and its rational are discussed. Finally, representative experimental results of the test program are presented, and are compared to pretest computer model predictions. Good agreement between predicted and measured data has served to validate the thruster performance computer models.

  5. Using UCODE_2005 and PHREEQC to determine thermodynamic constants from experimental data.

    PubMed

    Skold, Magnus E; Thyne, Geoffrey D; McCray, John E

    2007-01-01

    This article presents a method for estimating chemical thermodynamic constants from experimental data using the two computer programs UCODE_2005 and PHREEQC. As an example, the conditional stability constant for lead (Pb) complexation by a remediation agent (carboxymethyl-beta-cyclodextrin) is estimated, but the method can be applied to estimate other thermodynamic parameters such as sorption constants and degradation rate constants. Advantages of this technique include estimation of uncertainties associated with estimated parameters, evaluation of information content of observations, statistical evaluation of the appropriateness of the conceptual model, and statistical-based comparison of different models.

  6. A combined experimental-numerical approach for determining mechanical properties of aluminum subjects to nanoindentation.

    PubMed

    Liu, Mao; Lu, Cheng; Tieu, Kiet Anh; Peng, Ching-Tun; Kong, Charlie

    2015-10-14

    A crystal plasticity finite element method (CPFEM) model has been developed to investigate the mechanical properties and micro-texture evolution of single-crystal aluminum induced by a sharp Berkovich indenter. The load-displacement curves, pile-up patterns and lattice rotation angles from simulation are consistent with the experimental results. The pile-up phenomenon and lattice rotation have been discussed based on the theory of crystal plasticity. In addition, a polycrystal tensile CPFEM model has been established to explore the relationship between indentation hardness and yield stress. The elastic constraint factor C is slightly larger than conventional value 3 due to the strain hardening.

  7. The density-of-states concept versus the experimentally determined distribution of activation energies

    SciTech Connect

    Adriaenssens, G.J.; Arkhipov, V.I.

    1996-12-31

    Random fluctuations of localized state energies will result in thermal release of carriers trapped in those states at shorter times than would be observed from a stationary distribution of the same energies. An experimentally observed distribution of activation energies will hence differ from the distribution of average energies of the states involved. It will also be temperature-dependent. In a-Si:H, low-frequency fluctuations with a spectrum comparable to the one of 1/f noise, can account for the measured temperature dependence of the distribution. They also explain the apparent shift in localized-state energy under steady-state illumination.

  8. Polynomial dual energy inverse functions for bone Calcium/Phosphorus ratio determination and experimental evaluation.

    PubMed

    Sotiropoulou, P; Fountos, G; Martini, N; Koukou, V; Michail, C; Kandarakis, I; Nikiforidis, G

    2016-12-01

    An X-ray dual energy (XRDE) method was examined, using polynomial nonlinear approximation of inverse functions for the determination of the bone Calcium-to-Phosphorus (Ca/P) mass ratio. Inverse fitting functions with the least-squares estimation were used, to determine calcium and phosphate thicknesses. The method was verified by measuring test bone phantoms with a dedicated dual energy system and compared with previously published dual energy data. The accuracy in the determination of the calcium and phosphate thicknesses improved with the polynomial nonlinear inverse function method, introduced in this work, (ranged from 1.4% to 6.2%), compared to the corresponding linear inverse function method (ranged from 1.4% to 19.5%).

  9. Determination and Finite Element Validation of the WYPIWYG Strain Energy of Superficial Fascia from Experimental Data.

    PubMed

    Latorre, Marcos; Peña, Estefanía; Montáns, Francisco J

    2017-03-01

    What-You-Prescribe-Is-What-You-Get (WYPIWYG) procedures are a novel and general phenomenological approach to modelling the behavior of soft materials, applicable to biological tissues in particular. For the hyperelastic case, these procedures solve numerically the nonlinear elastic material determination problem. In this paper we show that they can be applied to determine the stored energy density of superficial fascia. In contrast to the usual approach, in such determination no user-prescribed material parameters and no optimization algorithms are employed. The strain energy densities are computed solving the equilibrium equations of the set of experiments. For the case of superficial fascia it is shown that the mechanical behavior derived from such strain energies is capable of reproducing simultaneously the measured load-displacement curves of three experiments to a high accuracy.

  10. Experimental verification of a real-time program for the determination of temperature and sag of overhead lines

    SciTech Connect

    Bush, R.A.; Black, W.Z.; Byrd, W.R.; Champion, T.C. III

    1983-07-01

    An outdoor test facility was used to experimentally verify real-time overhead conductor ampacity and sag programs. The facility consists of a 213m span of 26/7 336 kcmil ACSR conductor completely instrumented with 13 thermocouples as well as a sag and tension device. A weather station mounted near mid-span monitors all pertinent weather conditions. The measured conductor temperatures fluctuated significantly along the length of the test span. Spanwise variations in the measured instantaneous temperatures were frequently in excess of 10/sup 0/C for a wide variety of conductor currents and weather conditions. The conductor temperatures predicted by the real-time ampacity program were within 10/sup 0/C of the average measured conductor temperatures for all tests. Measured conductor sags were within 5 percent of values predicted by a real-time sag program. The results of the experimental project show that accurate predictions of real-time conductor temperatures and sags can be achieved by knowing the conductor current, wind speed, wind direction and the ambient air temperature. Therefore, computer programs are capable of predicting conductor temperatures and sags with a minimum amount of weather data provided by a simple and inexpensive weather station. Instrumentation placed on the conductor is not necessary for execution of the ampacity and sag programs.

  11. Technical Note: Experimental determination of the effective point of measurement of two cylindrical ionization chambers in a clinical proton beam

    SciTech Connect

    Sugama, Yuya; Nishio, Teiji; Onishi, Hiroshi

    2015-07-15

    Purpose: IAEA TRS-398 notes that cylindrical ionization chambers are preferred for reference proton dosimetry. If a cylindrical ionization chamber is used in a phantom to measure the dose as a function of depth, the effective point of measurement (EPOM) must be taken into account. IAEA TRS-398 recommends a displacement of 0.75 times the inner cavity radius (0.75R) for heavy ion beams. Theoretical models by Palmans and by Bhullar and Watchman confirmed this value. However, the experimental results vary from author to author. The purpose of this study is to accurately measure the displacement and explain the past experimental discrepancies. Methods: In this work, we measured the EPOM of cylindrical ionization chambers with high accuracy by comparing the Bragg-peak position obtained with cylindrical ionization chambers (PTW 30013, PTW 31016) to that obtained using a plane-parallel ionization chamber (PTW 34045). Results: The EPOMs of PTW 30013 and 31016 were shifted by 0.92 ± 0.07 R with R = 3.05 mm and 0.90 ± 0.14 R with R = 1.45 mm, respectively, from the reference point toward the source. Conclusions: The EPOMs obtained were greater than the value of 0.75R proposed by the IAEA TRS-398 and the analytical results.

  12. Chaos and simple determinism in reversed field pinch plasmas: Nonlinear analysis of numerical simulation and experimental data

    SciTech Connect

    Watts, C.A.

    1993-09-01

    In this dissertation the possibility that chaos and simple determinism are governing the dynamics of reversed field pinch (RFP) plasmas is investigated. To properly assess this possibility, data from both numerical simulations and experiment are analyzed. A large repertoire of nonlinear analysis techniques is used to identify low dimensional chaos in the data. These tools include phase portraits and Poincare sections, correlation dimension, the spectrum of Lyapunov exponents and short term predictability. In addition, nonlinear noise reduction techniques are applied to the experimental data in an attempt to extract any underlying deterministic dynamics. Two model systems are used to simulate the plasma dynamics. These are the DEBS code, which models global RFP dynamics, and the dissipative trapped electron mode (DTEM) model, which models drift wave turbulence. Data from both simulations show strong indications of low dimensional chaos and simple determinism. Experimental date were obtained from the Madison Symmetric Torus RFP and consist of a wide array of both global and local diagnostic signals. None of the signals shows any indication of low dimensional chaos or low simple determinism. Moreover, most of the analysis tools indicate the experimental system is very high dimensional with properties similar to noise. Nonlinear noise reduction is unsuccessful at extracting an underlying deterministic system.

  13. Experimental determination of optimal root-mean-square deviations of macromolecular bond lengths and angles from their restrained ideal values.

    PubMed

    Tickle, Ian J

    2007-12-01

    A number of inconsistencies are apparent in the recent research paper by Jaskolski et al. [(2007), Acta Cryst. D63, 611-620] concerning their recommendations for the values of the magnitude and resolution-dependence of the root-mean-square deviations (RMSDs) of bond lengths and angles from their restrained ideal values in macromolecular refinement, as well as their suggestions for the use of variable standard uncertainties dependent on atomic displacement parameters (ADPs) and occupancies. Whilst many of the comments and suggestions in the paper regarding updates for the ideal geometry values proposed by Engh and Huber are entirely reasonable and supported by the experimental evidence, the recommendations concerning the optimal values of RMSDs appear to be in conflict with previous experimental and theoretical work in this area [Tickle et al. (1998), Acta Cryst. D54, 243-252] and indeed appear to be based on a misunderstanding of the distinction between RMSD and standard uncertainty (SU). In contrast, it is proposed here that the optimal values of all desired weighting parameters, in particular the weighting parameters for the ADP differences and for the diffraction terms, be estimated by the purely objective procedure of maximizing the experiment-based log(free likelihood). In principle, this allows all weighting parameters that are not known accurately a priori to be scaled globally, relative to those that are known accurately, for an optimal refinement. The RMS Z score (RMSZ) is recommended as a more satisfactory statistic than the RMSD to assess the extent to which the geometry deviates from the ideal values and a theoretical rationale for the results obtained is presented in which the optimal RMSZ is identified as the calculated versus true Z-score correlation coefficient, the latter being a monotonic function of the resolution cutoff of the data. Regarding the proposal to use variable standard uncertainties, it is suggested that any departure from the current

  14. Experimental determination of the complex stiffness tensor and Euler angles in anisotropic media using ultrasonic waves

    SciTech Connect

    Alaoui-Ismaili, N.; Guy, P.; Chassignole, B.

    2014-02-18

    The aim of this work is to measure the complex elastic tensor and Euler angles in very complex anisotropic media like austenitic steel welds, by inverse problem resolution from experimental data. The obtained experimental characteristics of the anisotropic material will be injected in a FE code developed by EDF enabling the simulation of an actual ultrasonic NDE of welds. The present work aims to provide reliable input data to the 3D future development of the code. In particular, this complex elastic tensor will allow to predict by modeling beam skewing ant attenuation in an austenitic weld. The investigation of such anisotropic media is very complex because of the directional dependency of the elastic stiffness tensor. Then we will discuss the use of a hybrid genetic algorithm to overcome this difficulty. The identification method is based on waveforms spectra reconstruction associated to a physical model describing wave propagation in plates, during underwater measurements. The entire procedure is qualified and validated using simulated data. Moreover, a comparison of the estimated elastic coefficients with literature values and ultrasonic measurements obtained in transmission is also given, at the end of the paper.

  15. Experimental determination of the complex stiffness tensor and Euler angles in anisotropic media using ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Alaoui-Ismaili, N.; Guy, P.; Chassignole, B.

    2014-02-01

    The aim of this work is to measure the complex elastic tensor and Euler angles in very complex anisotropic media like austenitic steel welds, by inverse problem resolution from experimental data. The obtained experimental characteristics of the anisotropic material will be injected in a FE code developed by EDF enabling the simulation of an actual ultrasonic NDE of welds. The present work aims to provide reliable input data to the 3D future development of the code. In particular, this complex elastic tensor will allow to predict by modeling beam skewing ant attenuation in an austenitic weld. The investigation of such anisotropic media is very complex because of the directional dependency of the elastic stiffness tensor. Then we will discuss the use of a hybrid genetic algorithm to overcome this difficulty. The identification method is based on waveforms spectra reconstruction associated to a physical model describing wave propagation in plates, during underwater measurements. The entire procedure is qualified and validated using simulated data. Moreover, a comparison of the estimated elastic coefficients with literature values and ultrasonic measurements obtained in transmission is also given, at the end of the paper.

  16. Intrinsic determinants of synaptic phenotype: an experimental study of abducens internuclear neurons connecting with anomalous targets.

    PubMed

    de la Cruz, R R; Benítez-Temiño, B; Pastor, A M

    2002-01-01

    The present experiments investigate the role of postsynaptic neurons in the morphological differentiation of presynaptic terminals that are formed de novo in the adult CNS. Abducens internuclear neurons in the adult cat were chosen as the experimental model. These neurons project onto the contralateral medial rectus motoneurons of the oculomotor nucleus. Abducens internuclear axon terminals were identified by their anterograde labeling with biocytin and analyzed at the electron microscopic level. To promote the formation of new synapses, two different experimental approaches were used. First, after the selective ablation of medial rectus motoneurons with ricin, abducens internuclear neurons reinnervated the neighboring oculomotor internuclear neurons. Second, after axotomy followed by embryonic cerebellar grafting, abducens internuclear axons invaded the implanted tissue and established synaptic connections in both the molecular and granule cell layer. Boutons contacting the oculomotor internuclear neurons developed ultrastructural characteristics that resembled the control synapses on medial rectus motoneurons. In the grafted cerebellar tissue, abducens internuclear axons and terminals did not resemble climbing or mossy fibers but showed similarities with control boutons. However, labeled boutons analyzed in the granule cell layer established a higher number of synaptic contacts than controls. This could reflect a trend towards the mossy fiber phenotype, although labeled boutons significantly differed in every measured parameter with the mossy fiber rosettes found in the graft. We conclude that at least for the abducens internuclear neurons, the ultrastructural differentiation of axon terminals reinnervating novel targets in the adult brain seems to be mainly under intrinsic control, with little influence by postsynaptic cells.

  17. Determination of ensemble-average pairwise root mean-square deviation from experimental B-factors.

    PubMed

    Kuzmanic, Antonija; Zagrovic, Bojan

    2010-03-03

    Root mean-square deviation (RMSD) after roto-translational least-squares fitting is a measure of global structural similarity of macromolecules used commonly. On the other hand, experimental x-ray B-factors are used frequently to study local structural heterogeneity and dynamics in macromolecules by providing direct information about root mean-square fluctuations (RMSF) that can also be calculated from molecular dynamics simulations. We provide a mathematical derivation showing that, given a set of conservative assumptions, a root mean-square ensemble-average of an all-against-all distribution of pairwise RMSD for a single molecular species, (1/2), is directly related to average B-factors () and (1/2). We show this relationship and explore its limits of validity on a heterogeneous ensemble of structures taken from molecular dynamics simulations of villin headpiece generated using distributed-computing techniques and the Folding@Home cluster. Our results provide a basis for quantifying global structural diversity of macromolecules in crystals directly from x-ray experiments, and we show this on a large set of structures taken from the Protein Data Bank. In particular, we show that the ensemble-average pairwise backbone RMSD for a microscopic ensemble underlying a typical protein x-ray structure is approximately 1.1 A, under the assumption that the principal contribution to experimental B-factors is conformational variability.

  18. Urban artificial light emission function determined experimentally using night sky images

    NASA Astrophysics Data System (ADS)

    Solano Lamphar, Héctor Antonio; Kocifaj, Miroslav

    2016-09-01

    To date, diverse approximations have been developed to interpret the radiance of a night sky due to light emissions from ground-based light sources. The radiant intensity distribution as a function of zenith angle is one of the most unknown properties because of the collective effects of all artificial, private and public lights. The emission function (EF) is, however, a key property in modeling the skyglow under arbitrary conditions, and thus it is equally required by modelers, light pollution researchers, and also experimentalists who are using specialized devices to study the diffuse light of a night sky. In this paper, we present the second generation of a dedicated measuring system intended for routine monitoring of a night sky in any region. The experimental technology we have developed is used to interpret clear sky radiance data recorded at a set of discrete distances from a town (or city) with the aim to infer the fraction of upwardly emitted light (F), that is a parameter scaling the bulk EF. The retrieval of the direct upward emissions has been improved by introducing a weighting factor that is used to eliminate imperfections of experimental data and thus to make the computation of F more stable when processing the radiance data taken at two adjacent measuring points. The field experiments made in three Mexican cities are analyzed and the differences found are discussed.

  19. Determination of the Molar Volume of Hydrogen from the Metal-Acid Reaction: An Experimental Alternative.

    ERIC Educational Resources Information Center

    de Berg, Kevin; Chapman, Ken

    1996-01-01

    Describes an alternative technique for determining the molar volume of hydrogen from the metal-acid reaction in which the metal sample is encased in a specially prepared cage and a pipette filler is used to fill an inverted burette with water. Eliminates some difficulties encountered with the conventional technique. (JRH)

  20. Experimental Determination of the Mass of Air Molecules from the Law of Atmospheres.

    ERIC Educational Resources Information Center

    Hayn, Carl H.; Galvin, Vincent, Jr.

    1979-01-01

    A gas pressure gauge has been constructed for use in a student experiment involving the law of atmospheres. From pressure data obtained at selected elevations the average mass of air molecules is determined and compared to that calculated from the molecular weights and percentages of constituents to the air. (Author/BB)

  1. A new method for experimental determination of the series resistance of a solar cell

    SciTech Connect

    Araujo, G.L.; Sanchez, E.

    1982-10-01

    A new method for determining the series resistance of a solar cell from illuminated I-V measurements is presented. This technique takes advantage of the special feature of integration as a procedure to smooth data errors. The R/SUB s/ obtained represents the resistive effects globally.

  2. Experimental Determination of Unknown Masses and Their Positions in a Mechanical Black Box

    ERIC Educational Resources Information Center

    Chakrabarti, Bhupati; Pathare, Shirish; Huli, Saurabhee; Nachane, Madhura

    2013-01-01

    An experiment with a mechanical black box containing unknown masses is presented. The experiment involves the determination of these masses and their locations by performing some nondestructive tests. The set-ups are inexpensive and easy to fabricate. They are very useful to gain an understanding of some well-known principles of mechanics.

  3. Experimental Determination of pK[subscript a] Values by Use of NMR Chemical Shifts, Revisited

    ERIC Educational Resources Information Center

    Gift, Alan D.; Stewart, Sarah M.; Bokashanga, Patrick Kwete

    2012-01-01

    This laboratory experiment, using proton NMR spectroscopy to determine the dissociation constant for heterocyclic bases, has been modified from a previously described experiment. A solution of a substituted pyridine is prepared using deuterium oxide (D[subscript 2]O) as the solvent. The pH of the solution is adjusted and proton NMR spectra are…

  4. A sensitive and accurate method for the determination of perfluoroalkyl and polyfluoroalkyl substances in human serum using a high performance liquid chromatography-online solid phase extraction-tandem mass spectrometry.

    PubMed

    Yu, Chang Ho; Patel, Bhupendra; Palencia, Marilou; Fan, Zhihua Tina

    2017-01-13

    A selective, sensitive, and accurate analytical method for the measurement of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in human serum, utilizing LC-MS/MS (liquid chromatography-tandem mass spectrometry), was developed and validated according to the Centers for Disease Control and Prevention (CDC) guidelines for biological sample analysis. Tests were conducted to determine the optimal analytical column, mobile phase composition and pH, gradient program, and cleaning procedure. The final analytical column selected for analysis was an extra densely bonded silica-packed reverse-phase column (Agilent XDB-C8, 3.0×100mm, 3.5μm). Mobile phase A was an aqueous buffer solution containing 10mM ammonium acetate (pH=4.3). Mobile phase B was a mixture of methanol and acetonitrile (1:1, v/v). The gradient program was programmed by initiating a fast elution (%B, from 40 to 65%) between 1.0 and 1.5min, followed by a slow elution (%B: 65-80%) in the period of 1.5-7.5min. The cleanup procedures were augmented by cleaning with (1) various solvents (isopropyl alcohol, methanol, acetonitrile, and reverse osmosis-purified water); (2) extensive washing steps for the autosampler and solid phase extraction (SPE) cartridge; and (3) a post-analysis cleaning step for the whole system. Under the above conditions, the resolution and sensitivity were significantly improved. Twelve target PFASs were baseline-separated (2.5-7.0min) within a 10-min of acquisition time. The limits of detection (LODs) were 0.01ng/mL or lower for all of the target compounds, making this method 5 times more sensitive than previously published methods. The newly developed method was validated in the linear range of 0.01-50ng/mL, and the accuracy (recovery between 80 and 120%) and precision (RSD<20%) were acceptable at three spiked levels (0.25, 2.5, and 25ng/mL). The method development and validation results demonstrated that this method was precise, accurate, and robust, with high-throughput (∼10min per

  5. Experimental determination of layer cloud edge charging from cosmic ray ionisation

    NASA Astrophysics Data System (ADS)

    Nicoll, K. A.; Harrison, R. G.

    2010-07-01

    The cloud-air transition zone at stratiform cloud edges is an electrically active region where droplet charging has been predicted. Cloud edge droplet charging is expected from vertical flow of cosmic ray generated atmospheric ions in the global electric circuit. Experimental confirmation of stratiform cloud edge electrification is presented here, through charge and droplet measurements made within an extensive layer of supercooled stratiform cloud, using a specially designed electrostatic sensor. Negative space charge up to 35 pC m-3 was found in a thin (<100 m) layer at the lower cloud boundary associated with the clear air-cloud conductivity gradient, agreeing closely with space charge predicted from the measured droplet concentration using ion-aerosol theory. Such charge levels carried by droplets are sufficient to influence collision processes between cloud droplets.

  6. Experimental determination of the coefficient of drag of a tennis ball

    NASA Astrophysics Data System (ADS)

    Zayas, Joseph M.

    1986-07-01

    The standard projectile motion experiment in the general physics laboratory using a spring gun and metal projectile is not sufficiently sensitive to detect air resistance effects of the ball's motion. These effects may be successfully studied by using a commercial tennis ball pitching machine which is capable of launching balls with speeds up to about 27 m/ s with negligible spin. Assuming an air resistance force of the form f=-bv2, the coefficient b may be shown by direct solution of the equations of motion to be dependent on the muzzle velocity, the horizontal speed of the ball as it strikes the ground, and its landing angle. By measuring these quantities, b may be obtained and its value then used to compute the drag coefficient CD for the ball. Experimental values of CD compare well with similar values obtained for smooth spheres by other methods.

  7. Experimental and analytical determination of gear tooth temperatures with oil jet lubrication

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Akin, L. S.

    1982-01-01

    Gear tooth average and instantaneous surface temperatures were measured with a fast response infrared radiometric microscope, while operating at arious speeds, loads and oil jet pressures. Increased oil jet pressure had a significant effect on both average and peak surface temperatures at all test conditions, increasing the speed at constant load and increasing the load at constant speed causes a significant rise in average and peak surface temperatures of gear teeth. A gear tooth temperature analysis was conducted by a finite element method combined with a calculated heat input and oil jet impingment depth with estimated heat transfer coefficients based on the experimental data. It is concluded that oil jet pressures required for adequate cooling at high load and speed conditions must be high enough to get full penetration depth of the teeth.

  8. Modelling and experimental determination of the replication of a cylindrical shape relief

    NASA Astrophysics Data System (ADS)

    Sahli, M.; Millot, C.; Roques-Carmes, C.; Malek, C. Khan; Gelin, J. C.

    2007-04-01

    In that paper, one uses the concepts of contact mechanics to describe the quality of reproduction of cylindrical cavity shape by hot embossing. It results in a negative replica of the initial shape. This model takes into account the deformation of the polymer material imposed by the forming process. These results point out the influence of experimental parameters (temperature, pressure) as well as those of the elastic modulus (Young's modulus and Poisson's ratio). The analytical data are compared with the metrology results obtained using a scanning mechanical microscope in two or three-dimensional mode. The set of data enables a predictive approach of the engraving quality depending on the polymer mechanical properties. The final goal is to adapt this model to the hot embossing process.

  9. Experimental determination of the tonal noise sources in a centrifugal fan

    NASA Astrophysics Data System (ADS)

    Velarde-Suárez, Sandra; Ballesteros-Tajadura, Rafael; Pablo Hurtado-Cruz, Juan; Santolaria-Morros, Carlos

    2006-08-01

    In this work, an experimental study about the aerodynamic tonal noise sources in a centrifugal fan with backward-curved blades has been carried out. Acoustic pressure measurements at the fan exit duct and pressure fluctuation measurements on the volute surface have been made for different flow rates. A correlation study of both pressure signals has been made in order to explain some of the features of the aerodynamic tonal noise generation. A strong source of noise caused by the interaction between the fluctuating flow leaving the impeller and the volute tongue is appreciated. The unsteady forces exerted on the fan blades constitute another noise generation mechanism, which affects the whole extension of the impeller, thus transmitting pressure fluctuations to the entire volute casing. The relative importance of this mechanism compared to the impeller-tongue interaction depends on the flow rate.

  10. Experimental determination of the impact of polysilicon LER on sub-100-nm transistor performance

    NASA Astrophysics Data System (ADS)

    Patterson, Kyle; Sturtevant, John L.; Alvis, John R.; Benavides, Nancy; Bonser, Douglas; Cave, Nigel; Nelson-Thomas, Carla; Taylor, William D.; Turnquest, Karen L.

    2001-08-01

    Photoresist line edge roughness (LER) has long been feared as a potential limitation to the application of various patterning technologies to actual devices. While this concern seems reasonable, experimental verification has proved elusive and thus LER specifications are typically without solid parametric rationale. We report here the transistor device performance impact of deliberate variations of polysilicon gate LER. LER magnitude was attenuated by more than a factor of 5 by altering the photoresist type and thickness, substrate reflectivity, masking approach, and etch process. The polysilicon gate LER for nominally 70 - 150 nm devices was quantified using digital image processing of SEM images, and compared to gate leakage and drive current for variable length and width transistors. With such comparisons, realistic LER specifications can be made for a given transistor. It was found that subtle cosmetic LER differences are often not discernable electrically, thus providing hope that LER will not limit transistor performance as the industry migrates to sub-100 nm patterning.

  11. Determination of the molecular signature of fossil conifers by experimental palaeochemotaxonomy - Part 1: The Araucariaceae family

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Hautevelle, Y.; Michels, R.

    2012-08-01

    Several extant species of the Araucariaceae family (one of the families of conifers) were invested for the experimental artificial maturation by confined pyrolysis, in order to realize the transformation of biomolecules to geomolecules in laboratory conditions. The experimental study of diagenetized molecular signatures of the Araucariaceae species (common, inter- and infra-generic characteristics) allow to complete our knowledge in botanical palaeochemotaxonomy. Such knowledge is relevant to the reconstitution of palaeoflora and palaeoclimatic reconstruction, archaeology and environmental studies. In this work, major carbon skeleton types of Araucariaceae are detected in the organic solvent extracts of fresh and pyrolyzed plants using gas chromatography-mass spectrometry. The results show that all species of Araucariaceae are firstly characterized by a predominance of saturated tetracyclic diterpenoids. Moreover, the Araucaria genus shows a high relative abundance of bicyclic sesquiterpenoids, particularly compounds of the cadalane-type compounds accompanied by those of eudesmane-type, bisabolane-type as well as chamazulene, pentamethyl-dihydroindenes. Diterpenoids are of the labdane-type, isopimarane, abietane-type (essentially derived from abietanoic acids) as well as isohexyl alkylaromatic hydrocarbons. Compared to the tetracyclic diterpenoids, these compounds show a relatively lower abundance, reaching trace levels in the case of saturated abietanes. Distribution of sesqui- and diterpenoids of Agathis shows some similarities to that of Araucaria, with the exception of one species, in which the tetracyclic compounds are absent and the abietane-type (essentially derived from abietanoic acids) predominant. High similarities between the Wollemia and Araucaria genera are observed. Both are characterized by some high relative abundance of tetracyclic compounds with no predominance of other specific diterpenoids.

  12. Experimental determination of friction factors for mist and foam drilling and well cleanout operations

    SciTech Connect

    Okpobiri, G.A.; Ikoku, C.U.

    1983-12-01

    This work covers both theoretical and experimental analysis of frictional losses due to the presence of solids in vertical flow of solids-foam slurries. RabinowitshMooney generalized flow equations for time-independent fluids from the theoretical basis for the rheological analysis. Experimental work was done with an apparatus designed to simulate actual field conditions as closely as possible. The test section consists of an annulus with 4.0-in. casing and 1.5-in. tubing. The surface active agent used is an aniomic biodegradable foamer (ADOFOAM BF-1) and constitutes 1 percent of the liquid volume. Foam qualities and wall shear rates ranged from 0.64 to 0.99, and 100 to 1000 sec/sup -1/, respectively. Semi-empirical equations for predicting friction factors due to solids are presented. Sandstone and limestone particles were used. Average particle size ranged from 0.025 to 0.11 in. and a total of 337 data points were used in the correlations. Data collection was carried out above solid saltation velocities under fully developed steady-state flow conditions. Results show that the friction factor of suspension can be treated as the sum of the friction factor due to the fluid and that due to the solids. For a constant foam Reynold's number, the frictional losses due to the presence of solids increase as the solids mass flow rate (or solids content) increases. Solids friction factor was found to increase with increasing particles Froude number (gd /SUB s/ /V/sup 2/ /SUB F/ ), density ratio (p /SUB s/ /p /SUB F/ ), solids concentration, but decreases with increasing fluid Reynolds' number.

  13. Determining the mechanical constitutive properties of metals as a function of strain rate and temperature: A combined experimental and modeling approach

    SciTech Connect

    I. M. Robertson; A. Beaudoin; J. Lambros

    2004-01-05

    OAK-135 Development and validation of constitutive models for polycrystalline materials subjected to high strain rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions (foreign object damage, high-strain rate forging, high-speed sheet forming, deformation behavior during forming, response to extreme conditions, etc.). To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be closely coupled with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experimentation is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models, which will include dislocation-grain boundary interactions for polycrystalline systems. One aspect of the program will involve the dire ct

  14. Accurate ab Initio Spin Densities.

    PubMed

    Boguslawski, Katharina; Marti, Konrad H; Legeza, Ors; Reiher, Markus

    2012-06-12

    We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as a basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys.2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CASCI-type wave function provides insight into chemically interesting features of the molecule under study such as the distribution of α and β electrons in terms of Slater determinants, CI coefficients, and natural orbitals. The methodology is applied to an iron nitrosyl complex which we have identified as a challenging system for standard approaches [J. Chem. Theory Comput.2011, 7, 2740].

  15. Experimental determination of the filling coefficient for an aspirated spark-ignition engine

    NASA Astrophysics Data System (ADS)

    Raţiu, S.; Alexa, V.; Kiss, I.; Cioată, V.

    2017-01-01

    This study aims at determining, by experiment, the filling coefficient of a spark-ignition, normal aspirated engine, with carburettor. For this purpose, a pilot plant was designed for measuring the pressure at various points on the route, simulating a stationary air flow regime by means of a vacuum pump. Measurements were made for various lifting heights of the intake valve and various opening positions of the throttle body, thus highlighting how their influence on the pressure loss and on the filling coefficient.

  16. Feedback about More Accurate versus Less Accurate Trials: Differential Effects on Self-Confidence and Activation

    ERIC Educational Resources Information Center

    Badami, Rokhsareh; VaezMousavi, Mohammad; Wulf, Gabriele; Namazizadeh, Mahdi

    2012-01-01

    One purpose of the present study was to examine whether self-confidence or anxiety would be differentially affected by feedback from more accurate rather than less accurate trials. The second purpose was to determine whether arousal variations (activation) would predict performance. On Day 1, participants performed a golf putting task under one of…

  17. Comparison of experimental methods for determination of the volumetric mass transfer coefficient in fermentation processes

    NASA Astrophysics Data System (ADS)

    Tobajas, M.; García-Calvo, E.

    Mass transfer in bioreactors has been examined. In the present work, dynamic methods are used for the determination of KLa values for water, model media and a fermentation broth (Candida utilis) in an airlift reactor. The conventional dynamic method is applied at the end of the microbial process in order to avoid an alteration in the metabolism of the microorganisms. New dynamic methods are used to determine KLa in an airlift reactor during the microbial growth of Candida utilis on glucose. One of the methods is based on the continuous measurement of carbon dioxide production while the other method is based on the relationship between the oxygen transfer and biomass growth rates. These methods of determining KLa does not interfere with the microorganisms action. A theoretical mass transfer model has been used for KLa estimation for the systems described above. Some differences between calculated and measured values are found for fermentation processes due to the model is developed for two-phase air-water systems. Nevertheless, the average deviation between the predicted values and those obtained from the relationship between oxygen transfer and biomass production rates are lower than 25% in any case.

  18. Experimental determination of the metastable zone width of borax decahydrate by ultrasonic velocity measurement

    NASA Astrophysics Data System (ADS)

    Gürbüz, H.; Özdemir, B.

    2003-05-01

    The metastable zone width of borax decahydrate (disodium tetraborate decahydrate), represented by the maximum undercooling Δ Tmax, both in pure and impure aqueous solutions were determined according to polythermal method by using the ultrasonic technique. It is found that the metastable zone width of borax decahydrate in pure solutions determined by ultrasonic method fulfills well the linear relation between logΔ Tmax and log(-d T/d t). However, the sensitivity of the method using the ultrasonic technique increases with increasing saturation temperature, probably due to the increase of temperature dependence of solubility with increasing saturation temperature. A comparison of the nucleation temperatures from ultrasonic measurements and from visual determination shows that both detection techniques give almost the same results for borax decahydrate. The results obtained from ultrasonic measurements show, that the presence of Ca 2+ as impurity has only a small effect on the metastable zone width of borax decahydrate as long as the impurity concentrations is in the range of 25-200 ppm. Similar to the effect of Ca 2+, Mg 2+ also has a small effect on the metastable zone width of borax up to the impurity concentration of 100 ppm. However, the presence of 200 ppm Mg 2+ results in a reasonable increase of the metastable zone width.

  19. A new experimental method for the determination of the effective orifice area based on the acoustical source term

    NASA Astrophysics Data System (ADS)

    Kadem, L.; Knapp, Y.; Pibarot, P.; Bertrand, E.; Garcia, D.; Durand, L. G.; Rieu, R.

    2005-12-01

    The effective orifice area (EOA) is the most commonly used parameter to assess the severity of aortic valve stenosis as well as the performance of valve substitutes. Particle image velocimetry (PIV) may be used for in vitro estimation of valve EOA. In the present study, we propose a new and simple method based on Howe’s developments of Lighthill’s aero-acoustic theory. This method is based on an acoustical source term (AST) to estimate the EOA from the transvalvular flow velocity measurements obtained by PIV. The EOAs measured by the AST method downstream of three sharp-edged orifices were in excellent agreement with the EOAs predicted from the potential flow theory used as the reference method in this study. Moreover, the AST method was more accurate than other conventional PIV methods based on streamlines, inflexion point or vorticity to predict the theoretical EOAs. The superiority of the AST method is likely due to the nonlinear form of the AST. There was also an excellent agreement between the EOAs measured by the AST method downstream of the three sharp-edged orifices as well as downstream of a bioprosthetic valve with those obtained by the conventional clinical method based on Doppler-echocardiographic measurements of transvalvular velocity. The results of this study suggest that this new simple PIV method provides an accurate estimation of the aortic valve flow EOA. This new method may thus be used as a reference method to estimate the EOA in experimental investigation of the performance of valve substitutes and to validate Doppler-echocardiographic measurements under various physiologic and pathologic flow conditions.

  20. Experimental determination of the yield stress curve of the scotch pine wood materials

    NASA Astrophysics Data System (ADS)

    Günay, Ezgi; Aygün, Cevdet; Kaya, Şükrü Tayfun

    2013-12-01

    Yield stress curve is determined for the pine wood specimens by conducting a series of tests. In this work, pinewood is modeled as a composite material with transversely isotropic fibers. Annual rings (wood grain) of the wood specimens are taken as the major fiber directions with which the strain gauge directions are aligned. For this purpose, three types of tests are arranged. These are tensile, compression and torsion loading tests. All of the tests are categorized with respect to fiber orientations and their corresponding loading conditions. Each test within these categories is conducted separately. Tensile and compression tests are conducted in accordance with standards of Turkish Standards Institution (TSE) whereas torsion tests are conducted in accordance with Standards Australia. Specimens are machined from woods of Scotch pine which is widely used in boat building industries and in other structural engineering applications. It is determined that this species behaves more flexibly than the others. Strain gauges are installed on the specimen surfaces in such a way that loading measurements are performed along directions either parallel or perpendicular to the fiber directions. During the test and analysis phase of yield stress curve, orientation of strain gauge directions with respect to fiber directions are taken into account. The diagrams of the normal stress vs. normal strain or the shear stress vs. shear strain are plotted for each test. In each plot, the yield stress is determined by selecting the point on the diagram, the tangent of which is having a slope of 5% less than the slope of the elastic portion of the diagram. The geometric locus of these selected points constitutes a single yield stress curve on σ1-σ2 principal plane. The resulting yield stress curve is plotted as an approximate ellipse which resembles Tsai-Hill failure criterion. The results attained in this work, compare well with the results which are readily available in the literature.

  1. Experimental determination of safe atmospheric exposure concentrations of JP-10 jet fuel. Final technical report

    SciTech Connect

    Haun, C.C.; Kinkead, E.R.; Vernot, E.H.; MacEwen, J.D.; Bruner, R.H.

    1985-11-01

    Four animal species were exposed for 1 year to 100 ppm (556 cu mg/m) JP-10 to determine its long-term toxic and oncogenic effects. Rats, mice, and hamsters were maintained for 1 year poste posure, while dogs were held for 5 years post exposure. Mean body weights of exposed hamsters and make rats were lower than controls during exposure. Weight recovery occurred in hamsters, but not in male rats during post exposure phase of the study. Significant JP-10 exposure-related effects were renal tubular nephrosis together with an increase in benign and malignant renal-cell tumors in male rats.

  2. A new experimental method for determining liquid density and surface tension

    NASA Astrophysics Data System (ADS)

    Chou, Kjo-Chih; Hu, Jian-Hong

    1991-02-01

    A summary concerning the measurement of liquid density relying on the Archimedes principle has been presented, based on which a new effective method with a specially designed bob for determining liquid density has been suggested. The application of this method to ethyl alcohol solution and liquid glycerol, as well as a theoretical error analysis, shows that this new method is significant, because not only can it simplify the procedure of measurement but it can also offer more precise results. Besides, this method can further provide surface tension or contact angle simultaneously. It is expected that this new method will find its application in hightemperature melts.

  3. Chromium basalts - Experimental determination of redox states and partitioning among synthetic silicate phases

    NASA Technical Reports Server (NTRS)

    Schreiber, H. D.; Haskin, L. A.

    1976-01-01

    Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.

  4. Third-order elastic constants of diamond determined from experimental data

    DOE PAGES

    Winey, J. M.; Hmiel, A.; Gupta, Y. M.

    2016-06-01

    The pressure derivatives of the second-order elastic constants (SOECs) of diamond were determined by analyzing previous sound velocity measurements under hydrostatic stress [McSkimin and Andreatch, J. Appl. Phys. 43, 294 (1972)]. Furthermore, our analysis corrects an error in the previously reported results.We present a complete and corrected set of third-order elastic constants (TOECs) using the corrected pressure derivatives, together with published data for the nonlinear elastic response of shock compressed diamond [Lang and Gupta, Phys. Rev. Lett. 106, 125502 (2011)] and it differs significantly from TOECs published previously.

  5. Experimental method for the determination of adsorption-induced changes of pressure and surface stress in nanopores.

    PubMed

    Schappert, Klaus; Pelster, Rolf

    2017-02-15

    The change of surface stress is an important quantity characterising the behaviour of nanoporous systems, however, it is difficult to assess experimentally. In this letter we develop and demonstrate an experimental method for the determination of adsorption-induced changes of the surface stress in nanoporous materials. With the aid of ultrasonic measurements we determine the dependence of the adsorbate's longitudinal modulus [Formula: see text] on the adsorption-induced normal pressure, [Formula: see text], which is exerted by the adsorbate on the porous matrix. From this dependence we deduce the normal pressure at saturation, [Formula: see text], and thereby changes of the surface stress [Formula: see text] at the interface between the solid matrix and the liquid adsorbate. For the model system of argon in nanoporous glass (pore radius [Formula: see text] nm) the ultrasonic method reveals a value for [Formula: see text] that is in very good agreement with the theoretical value known for the argon-silica interface. The disclosure of this experimental method and its application on other systems will enable a better understanding of the behaviour of adsorbates in nanoporous materials.

  6. Experimental method for the determination of adsorption-induced changes of pressure and surface stress in nanopores

    NASA Astrophysics Data System (ADS)

    Schappert, Klaus; Pelster, Rolf

    2017-02-01

    The change of surface stress is an important quantity characterising the behaviour of nanoporous systems, however, it is difficult to assess experimentally. In this letter we develop and demonstrate an experimental method for the determination of adsorption-induced changes of the surface stress in nanoporous materials. With the aid of ultrasonic measurements we determine the dependence of the adsorbate’s longitudinal modulus {β\\text{Ar,\\text{ads}}} on the adsorption-induced normal pressure, Δ {{p}\\text{S}} , which is exerted by the adsorbate on the porous matrix. From this dependence we deduce the normal pressure at saturation, Δ p\\text{S}\\text{sat} , and thereby changes of the surface stress {{≤ft(Δ f\\right)}\\text{sat}} at the interface between the solid matrix and the liquid adsorbate. For the model system of argon in nanoporous glass (pore radius {{r}\\text{P}}=3.8 nm) the ultrasonic method reveals a value for Δ p\\text{S}\\text{sat} that is in very good agreement with the theoretical value known for the argon-silica interface. The disclosure of this experimental method and its application on other systems will enable a better understanding of the behaviour of adsorbates in nanoporous materials.

  7. Determination of pharmaceuticals in drinking water by CD-modified MEKC: separation optimization using experimental design.

    PubMed

    Drover, Vincent J; Bottaro, Christina S

    2008-12-01

    A suite of 12 widely used pharmaceuticals (ibuprofen, diclofenac, naproxen, bezafibrate, gemfibrozil, ofloxacin, norfloxacin, carbamazepine, primidone, sulphamethazine, sulphadimethoxine and sulphamethoxazole) commonly found in environmental waters were separated by highly sulphated CD-modified MEKC (CD-MEKC) with UV detection. An experimental design method, face-centred composite design, was employed to minimize run time without sacrificing resolution. Using an optimized BGE composed of 10 mM ammonium hydrogen phosphate, pH 11.5, 69 mM SDS, 6 mg/mL sulphated beta-CD and 8.5% v/v isopropanol, a separation voltage of 30 kV and a 48.5 cm x 50 microm id bare silica capillary at 30 degrees C allowed baseline separation of the 12 analytes in a total analysis time of 6.7 min. Instrument LODs in the low milligram per litre range were obtained, and when combined with offline preconcentration by SPE, LODs were between 4 and 30 microg/L.

  8. Diaplectic Glass Content in Experimentally Shock-loaded Quartz Determined by X-Ray Powder Diffraction

    NASA Technical Reports Server (NTRS)

    Skala, R.; Hoerz, F.; Langenhorst, F.

    2003-01-01

    Quartz is the most common mineral of terrestrial crustal rocks and thus a widespread indicator for impact cratering and associated shock metamorphism. Planar deformation features (PDFs) are among the most prominent and diagnostic shock features in quartz and they represent thin lamellae of glass that formed via solid-state transformations. This socalled 'diaplectic' glass becomes pervasive at higher pressures and results in optically isotropic and X-ray-amorphous phases that resemble texturally the original quartz grains (without evidence of melt flow). In the past, it has been shown that the amount of this amorphous material in experimentally shock-loaded quartz correlates with peak shock pressure. Both reports derive the glass content from density measurements of individual crystals employing the equation X(%) = (rho(sub x) - rho(sub 0))/(rho(sub x) - rho(sub gl)), where x and 0 stands for X-ray and average (optical) density, respectively. The density of glass, rho(sub gl), was adopted as 2.2 g/cu cm. Though the same procedures had been applied, the resulting glass content differs significantly among the above studies. In the present study, we are using a new approach based solely on the integral intensity of a single, carefully selected reflection in the XRD pattern, and we will compare our data to those reported in the literature.

  9. Experimental determination of melt interconnectivity and electrical conductivity in the upper mantle

    NASA Astrophysics Data System (ADS)

    Laumonier, Mickael; Farla, Robert; Frost, Daniel J.; Katsura, Tomoo; Marquardt, Katharina; Bouvier, Anne-Sophie; Baumgartner, Lukas P.

    2017-04-01

    The presence of a small fraction of basaltic melt is a potential explanation for mantle electrical conductivity anomalies detected near the top of the oceanic asthenosphere. The interpretation of magnetotelluric profiles in terms of the nature and proportion of melt, however, relies on mathematical models that have not been experimentally tested at realistically low melt fractions (<0.01). In order to address this, we have performed in situ electrical conductivity measurements on partially molten olivine aggregates. The obtained data suggest that the bulk conductivity follows the conventional Archie's law with the melt fraction exponents of 0.75 and 1.37 at melt fractions greater and smaller than 0.5 vol.% respectively at 1350 °C. Our results imply multiple conducting phases in melt-bearing olivine aggregate and a connectedness threshold at ∼0.5 vol.% of melt. The model predicts that the conductive oceanic upper asthenosphere contains 0.5 to 1 vol.% of melt, which is consistent with the durable presence of melt at depths over millions years while the oceanic plates spread apart at the mid-ocean ridge. Beneath ridges a minimum permeability may allow mid-ocean ridge basalts to rise out of the mantle, where our model indicates that melt is present in proportions of up to 4 vol.%.

  10. Experimental determination of the correlation properties of plasma turbulence using 2D BES systems

    NASA Astrophysics Data System (ADS)

    Fox, M. F. J.; Field, A. R.; van Wyk, F.; Ghim, Y.-c.; Schekochihin, A. A.; the MAST Team

    2017-04-01

    A procedure is presented to map from the spatial correlation parameters of a turbulent density field (the radial and binormal correlation lengths and wavenumbers, and the fluctuation amplitude) to correlation parameters that would be measured by a beam emission spectroscopy (BES) diagnostic. The inverse mapping is also derived, which results in resolution criteria for recovering correct correlation parameters, depending on the spatial response of the instrument quantified in terms of point-spread functions (PSFs). Thus, a procedure is presented that allows for a systematic comparison between theoretical predictions and experimental observations. This procedure is illustrated using the Mega-Ampere Spherical Tokamak BES system and the validity of the underlying assumptions is tested on fluctuating density fields generated by direct numerical simulations using the gyrokinetic code GS2. The measurement of the correlation time, by means of the cross-correlation time-delay method, is also investigated and is shown to be sensitive to the fluctuating radial component of velocity, as well as to small variations in the spatial properties of the PSFs.

  11. Experimental and Analytical Determination of the Geometric Far Field for Round Jets

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle; Bridges, James E.; Brown, Clifford E.; Khavaran, Abbas

    2005-01-01

    An investigation was conducted at the NASA Glenn Research Center using a set of three round jets operating under unheated subsonic conditions to address the question: "How close is too close?" Although sound sources are distributed at various distances throughout a jet plume downstream of the nozzle exit, at great distances from the nozzle the sound will appear to emanate from a point and the inverse-square law can be properly applied. Examination of normalized sound spectra at different distances from a jet, from experiments and from computational tools, established the required minimum distance for valid far-field measurements of the sound from subsonic round jets. Experimental data were acquired in the Aeroacoustic Propulsion Laboratory at the NASA Glenn Research Center. The WIND computer program solved the Reynolds-Averaged Navier-Stokes equations for aerodynamic computations; the MGBK jet-noise prediction computer code was used to predict the sound pressure levels. Results from both the experiments and the analytical exercises indicated that while the shortest measurement arc (with radius approximately 8 nozzle diameters) was already in the geometric far field for high-frequency sound (Strouhal number >5), low-frequency sound (Strouhal number <0.2) reached the geometric far field at a measurement radius of at least 50 nozzle diameters because of its extended source distribution.

  12. Experimental manipulation of seed shadows of an Afrotropical tree determines drivers of recruitment.

    PubMed

    Poulsen, John R; Clark, Connie J; Bolker, Benjamin M

    2012-03-01

    The loss of animals in tropical forests may alter seed dispersal patterns and reduce seedling recruitment of tree species, but direct experimental evidence is scarce. We manipulated dispersal patterns of Manilkara mabokeensis, a monkey-dispersed tree, to assess the extent to which spatial distributions of seeds drive seedling recruitment. Based on the natural seed shadow, we created seed distributions with seeds deposited under the canopy ("no dispersal"), with declining density from the tree ("natural dispersal"), and at uniform densities ("good dispersal"). These distributions mimicked dispersal patterns that could occur with the extirpation of monkeys, low levels of hunting, and high rates of seed dispersal. We monitored seedling emergence and survival for 18 months and recorded the number of leaves and damage to leaves. "Good dispersal" increased seedling survival by 26%, and "no dispersal" decreased survival by 78%, relative to "natural dispersal." Using a mixed-effects survival model, we decoupled the distance and density components of the seed shadow: seedling survival depended on the seed density, but not on the distance from the tree. Although community seedling diversity tended to decrease with longer dispersal distances, we found no conclusive evidence that patterns of seed dispersal influence the diversity of the seedling community. Local seed dispersal does affect seedling recruitment and survival, with better dispersal resulting in higher seedling recruitment; hence the loss of dispersal services that comes with the reduction or extirpation of seed dispersers will decrease regeneration of some tree species.

  13. SMA actuators for vibration control and experimental determination of model parameters dependent on ambient airflow velocity

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.

    2016-05-01

    This article demonstrates the practical applicability of a method of modelling shape memory alloys (SMAs) as actuators. For this study, a pair of SMA wires was installed in an antagonistic manner to form an actuator, and a linear differential equation that describes the behaviour of the actuator’s generated force relative to its input voltage was derived for the limited range below the austenite onset temperature. In this range, hysteresis need not be considered, and the proposed SMA actuator can therefore be practically applied in linear control systems, which is significant because large deformations accompanied by hysteresis do not necessarily occur in most vibration control cases. When specific values of the parameters used in the differential equation were identified experimentally, it became clear that one of the parameters was dependent on ambient airflow velocity. The values of this dependent parameter were obtained using an additional SMA wire as a sensor. In these experiments, while the airflow distribution around the SMA wires was varied by changing the rotational speed of the fans in the wind tunnels, an input voltage was conveyed to the SMA actuator circuit, and the generated force was measured. In this way, the parameter dependent on airflow velocity was estimated in real time, and it was validated that the calculated force was consistent with the measured one.

  14. Determination of DNA damage in experimental liver intoxication and role of N-acetyl cysteine.

    PubMed

    Aksit, Hasan; Bildik, Aysegül

    2014-11-01

    The present study aimed at detecting DNA damage and fragmentation as well as histone acetylation depending on oxidative stress caused by CCl4 intoxication. Also, the protective role of N-acetyl cysteine, a precursor for GSH, in DNA damage is investigated. Sixty rats were used in this study. In order to induce liver toxicity, CCl4 in was dissolved in olive oil (1/1) and injected intraperitoneally as a single dose (2 ml/kg). N-acetyl cysteine application (intraperitoneal, 50 mg/kg/day) was started 3 days prior to CCl4 injection and continued during the experimental period. Control groups were given olive oil and N-acetyl cysteine. After 6 and 72 h of CCl4 injection, blood and liver tissue were taken under ether anesthesia. Nuclear extracts were prepared from liver. Changes in serum AST and ALT activities as well as MDA, TAS, and TOS levels showed that CCl4 caused lipid peroxidation and liver damage. However, lipid peroxidation and liver damage were reduced in the N-acetyl cysteine group. Increased levels in 8-hydroxy-2-deoxy guanosine and histone acetyltransferase activities, decreased histone deacetylase activities, and DNA breakage detected in nuclear extracts showed that CCl4 intoxication induces oxidative stress and apoptosis in rat liver. The results of the present study indicate that N-acetyl cysteine has a protective effect on CCl4-induced DNA damage.

  15. REVIEW: A review of in vivo experimental methods to determine the composition of the human body

    NASA Astrophysics Data System (ADS)

    Sutcliffe, J. F.

    1996-05-01

    This review of experimental methods employed in the measurement of the composition of the human body covers the developments that have occurred over the past 30 years. Early methods such as hydrodensitometry and skinfold anthropometry have been superseded by dual-energy x-ray absorptiometry and bioelectrical impedance spectroscopy. The measurement of the whole-body abundance of certain elements by isotopic dilution, neutron activation analysis and x-ray fluorescence can give important information of clinical significance, but neutron activation facilities remain available in only a few centres worldwide. The relatively simple, rapid and risk-free electrical methods such as multifrequency bioelectrical impedance analysis, which can be employed at the bedside, have been found to be more complicated in their interpretation. Electromagnetic methods may only measure the composition of the human body at its surface. X-ray computed tomography and magnetic resonance imaging have not yet been employed much in body composition measurements. Some models for the composition of the human body are reviewed.

  16. Experimental determination of the spinel-garnet boundary in a Martian mantle composition

    NASA Technical Reports Server (NTRS)

    Patera, E. S.; Holloway, J. R.

    1982-01-01

    The high pressure reaction orthopyroxene + clinopyroxene + spinel to garnet + olivine is applicable to the mantle of Mars. Experimental reversals of this reaction in the system CaO-MgO-FeO-Al2O3-SiO2 have been made in the range 1000-1200 C using the bulk composition proposed by Morgan and Anders (1980). At 1000 C, 1100 C, and 1200 C the garnet-out equilibrium is bracketed at 10.8 + or - 0.5, 12.6 + or - 0.5, and 15.2 + or - 0.5 kbars, respectively. A dP/dT slope of 14.0 bar/K at 1000 C increasing to 26.0 bar/K at 1200 C has been inferred. Depending on bulk composition, the mantle of Mars is inferred to have a phase assemblage of either olivine + clinopyroxene + orthopyroxene + garnet or olivine + clinopyroxene + garnet + spinel. In the second, the partial melts will not be buffered by olivine and orthopyroxene and will have markedly lower silica activities than those of the terrestrial mantle.

  17. Accurate equilibrium structures for piperidine and cyclohexane.

    PubMed

    Demaison, Jean; Craig, Norman C; Groner, Peter; Écija, Patricia; Cocinero, Emilio J; Lesarri, Alberto; Rudolph, Heinz Dieter

    2015-03-05

    Extended and improved microwave (MW) measurements are reported for the isotopologues of piperidine. New ground state (GS) rotational constants are fitted to MW transitions with quartic centrifugal distortion constants taken from ab initio calculations. Predicate values for the geometric parameters of piperidine and cyclohexane are found from a high level of ab initio theory including adjustments for basis set dependence and for correlation of the core electrons. Equilibrium rotational constants are obtained from GS rotational constants corrected for vibration-rotation interactions and electronic contributions. Equilibrium structures for piperidine and cyclohexane are fitted by the mixed estimation method. In this method, structural parameters are fitted concurrently to predicate parameters (with appropriate uncertainties) and moments of inertia (with uncertainties). The new structures are regarded as being accurate to 0.001 Å and 0.2°. Comparisons are made between bond parameters in equatorial piperidine and cyclohexane. Another interesting result of this study is that a structure determination is an effective way to check the accuracy of the ground state experimental rotational constants.

  18. A versatile phenomenological model for the S-shaped temperature dependence of photoluminescence energy for an accurate determination of the exciton localization energy in bulk and quantum well structures

    NASA Astrophysics Data System (ADS)

    Dixit, V. K.; Porwal, S.; Singh, S. D.; Sharma, T. K.; Ghosh, Sandip; Oak, S. M.

    2014-02-01

    Temperature dependence of the photoluminescence (PL) peak energy of bulk and quantum well (QW) structures is studied by using a new phenomenological model for including the effect of localized states. In general an anomalous S-shaped temperature dependence of the PL peak energy is observed for many materials which is usually associated with the localization of excitons in band-tail states that are formed due to potential fluctuations. Under such conditions, the conventional models of Varshni, Viña and Passler fail to replicate the S-shaped temperature dependence of the PL peak energy and provide inconsistent and unrealistic values of the fitting parameters. The proposed formalism persuasively reproduces the S-shaped temperature dependence of the PL peak energy and provides an accurate determination of the exciton localization energy in bulk and QW structures along with the appropriate values of material parameters. An example of a strained InAs0.38P0.62/InP QW is presented by performing detailed temperature and excitation intensity dependent PL measurements and subsequent in-depth analysis using the proposed model. Versatility of the new formalism is tested on a few other semiconductor materials, e.g. GaN, nanotextured GaN, AlGaN and InGaN, which are known to have a significant contribution from the localized states. A quantitative evaluation of the fractional contribution of the localized states is essential for understanding the temperature dependence of the PL peak energy of bulk and QW well structures having a large contribution of the band-tail states.

  19. HipMatch: an object-oriented cross-platform program for accurate determination of cup orientation using 2D-3D registration of single standard X-ray radiograph and a CT volume.

    PubMed

    Zheng, Guoyan; Zhang, Xuan; Steppacher, Simon D; Murphy, Stephen B; Siebenrock, Klaus A; Tannast, Moritz

    2009-09-01

    The widely used procedure of evaluation of cup orientation following total hip arthroplasty using single standard anteroposterior (AP) radiograph is known inaccurate, largely due to the wide variability in individual pelvic orientation relative to X-ray plate. 2D-3D image registration methods have been introduced for an accurate determination of the post-operative cup alignment with respect to an anatomical reference extracted from the CT data. Although encouraging results have been reported, their extensive usage in clinical routine is still limited. This may be explained by their requirement of a CAD model of the prosthesis, which is often difficult to be organized from the manufacturer due to the proprietary issue, and by their requirement of either multiple radiographs or a radiograph-specific calibration, both of which are not available for most retrospective studies. To address these issues, we developed and validated an object-oriented cross-platform program called "HipMatch" where a hybrid 2D-3D registration scheme combining an iterative landmark-to-ray registration with a 2D-3D intensity-based registration was implemented to estimate a rigid transformation between a pre-operative CT volume and the post-operative X-ray radiograph for a precise estimation of cup alignment. No CAD model of the prosthesis is required. Quantitative and qualitative results evaluated on cadaveric and clinical datasets are given, which indicate the robustness and the accuracy of the program. HipMatch is written in object-oriented programming language C++ using cross-platform software Qt (TrollTech, Oslo, Norway), VTK, and Coin3D and is transportable to any platform.

  20. Experimental determination of radiated internal wave power without pressure field data

    SciTech Connect

    Lee, Frank M.; Morrison, P. J.; Paoletti, M. S.; Swinney, Harry L.

    2014-04-15

    We present a method to determine, using only velocity field data, the time-averaged energy flux (J) and total radiated power P for two-dimensional internal gravity waves. Both (J) and P are determined from expressions involving only a scalar function, the stream function ψ. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method agree to within 0.5% with results obtained using pressure and velocity data from the numerical simulation. The results for the radiated power computed from the stream function agree well with power computed from the velocity and pressure if the starting point for the stream function computation is on a solid boundary, but if a boundary point is not available, care must be taken to choose an appropriate starting point. We also test the stream function method by applying it to laboratory data for tidal flow past a knife edge, and the results are found to agree with the direct numerical simulation. The supplementary material includes a Matlab code with a graphical user interface that can be used to compute the energy flux and power from two-dimensional velocity field data.