Science.gov

Sample records for accurate experimental determination

  1. An experimental correction proposed for an accurate determination of mass diffusivity of wood in steady regime

    NASA Astrophysics Data System (ADS)

    Zohoun, Sylvain; Agoua, Eusèbe; Degan, Gérard; Perre, Patrick

    2002-08-01

    This paper presents an experimental study of the mass diffusion in the hygroscopic region of four temperate species and three tropical ones. In order to simplify the interpretation of the phenomena, a dimensionless parameter called reduced diffusivity is defined. This parameter varies from 0 to 1. The method used is firstly based on the determination of that parameter from results of the measurement of the mass flux which takes into account the conditions of operating standard device (tightness, dimensional variations and easy installation of samples of wood, good stability of temperature and humidity). Secondly the reasons why that parameter has to be corrected are presented. An abacus for this correction of mass diffusivity of wood in steady regime has been plotted. This work constitutes an advanced deal nowadays for characterising forest species.

  2. Accurate experimental determination of the isotope effects on the triple point temperature of water. I. Dependence on the 2H abundance

    NASA Astrophysics Data System (ADS)

    Faghihi, V.; Peruzzi, A.; Aerts-Bijma, A. T.; Jansen, H. G.; Spriensma, J. J.; van Geel, J.; Meijer, H. A. J.

    2015-12-01

    Variation in the isotopic composition of water is one of the major contributors to uncertainty in the realization of the triple point of water (TPW). Although the dependence of the TPW on the isotopic composition of the water has been known for years, there is still a lack of a detailed and accurate experimental determination of the values for the correction constants. This paper is the first of two articles (Part I and Part II) that address quantification of isotope abundance effects on the triple point temperature of water. In this paper, we describe our experimental assessment of the 2H isotope effect. We manufactured five triple point cells with prepared water mixtures with a range of 2H isotopic abundances encompassing widely the natural abundance range, while the 18O and 17O isotopic abundance were kept approximately constant and the 18O  -  17O ratio was close to the Meijer-Li relationship for natural waters. The selected range of 2H isotopic abundances led to cells that realised TPW temperatures between approximately  -140 μK to  +2500 μK with respect to the TPW temperature as realized by VSMOW (Vienna Standard Mean Ocean Water). Our experiment led to determination of the value for the δ2H correction parameter of A2H  =  673 μK / (‰ deviation of δ2H from VSMOW) with a combined uncertainty of 4 μK (k  =  1, or 1σ).

  3. Accurate determination of characteristic relative permeability curves

    NASA Astrophysics Data System (ADS)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  4. Accurate experimental determination of the isotope effects on the triple point temperature of water. II. Combined dependence on the 18O and 17O abundances

    NASA Astrophysics Data System (ADS)

    Faghihi, V.; Kozicki, M.; Aerts-Bijma, A. T.; Jansen, H. G.; Spriensma, J. J.; Peruzzi, A.; Meijer, H. A. J.

    2015-12-01

    This paper is the second of two articles on the quantification of isotope effects on the triple point temperature of water. In this second article, we address the combined effects of 18O and 17O isotopes. We manufactured five triple point cells with waters with 18O and 17O abundances exceeding widely the natural abundance range while maintaining their natural 18O/17O relationship. The 2H isotopic abundance was kept close to that of VSMOW (Vienna Standard Mean Ocean Water). These cells realized triple point temperatures ranging between  -220 μK to 1420 μK with respect to the temperature realized by a triple point cell filled with VSMOW. Our experiment allowed us to determine an accurate and reliable value for the newly defined combined 18, 17O correction parameter of AO  =  630 μK with a combined uncertainty of 10 μK. To apply this correction, only the 18O abundance of the TPW needs to be known (and the water needs to be of natural origin). Using the results of our two articles, we recommend a correction equation along with the coefficient values for isotopic compositions differing from that of VSMOW and compare the effect of this new equation on a number of triple point cells from the literature and from our own institute. Using our correction equation, the uncertainty in the isotope correction for triple point cell waters used around the world will be  <1 μK.

  5. Accurate abundance determinations in S stars

    NASA Astrophysics Data System (ADS)

    Neyskens, P.; Van Eck, S.; Plez, B.; Goriely, S.; Siess, L.; Jorissen, A.

    2011-12-01

    S-type stars are thought to be the first objects, during their evolution on the asymptotic giant branch (AGB), to experience s-process nucleosynthesis and third dredge-ups, and therefore to exhibit s-process signatures in their atmospheres. Until present, the modeling of these processes is subject to large uncertainties. Precise abundance determinations in S stars are of extreme importance for constraining e.g., the depth and the formation of the 13C pocket. In this paper a large grid of MARCS model atmospheres for S stars is used to derive precise abundances of key s-process elements and iron. A first estimation of the atmospheric parameters is obtained using a set of well-chosen photometric and spectroscopic indices for selecting the best model atmosphere of each S star. Abundances are derived from spectral line synthesis, using the selected model atmosphere. Special interest is paid to technetium, an element without stable isotopes. Its detection in stars is considered as the best possible signature that the star effectively populates the thermally-pulsing AGB (TP-AGB) phase of evolution. The derived Tc/Zr abundances are compared, as a function of the derived [Zr/Fe] overabundances, with AGB stellar model predictions. The computed [Zr/Fe] overabundances are in good agreement with the AGB stellar evolution model predictions, while the Tc/Zr abundances are slightly over-predicted. This discrepancy can help to set stronger constraints on nucleosynthesis and mixing mechanisms in AGB stars.

  6. The determination of accurate dipole polarizabilities alpha and gamma for the noble gases

    NASA Technical Reports Server (NTRS)

    Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almlof, Jan

    1991-01-01

    Accurate static dipole polarizabilities alpha and gamma of the noble gases He through Xe were determined using wave functions of similar quality for each system. Good agreement with experimental data for the static polarizability gamma was obtained for Ne and Xe, but not for Ar and Kr. Calculations suggest that the experimental values for these latter ions are too low.

  7. Precise and Accurate Density Determination of Explosives Using Hydrostatic Weighing

    SciTech Connect

    B. Olinger

    2005-07-01

    Precise and accurate density determination requires weight measurements in air and water using sufficiently precise analytical balances, knowledge of the densities of air and water, knowledge of thermal expansions, availability of a density standard, and a method to estimate the time to achieve thermal equilibrium with water. Density distributions in pressed explosives are inferred from the densities of elements from a central slice.

  8. 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.

  9. Accurate method for determining adhesion of cantilever beams

    SciTech Connect

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

    1999-07-01

    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. {copyright} {ital 1999 American Institute of Physics.}

  10. Reverse radiance: a fast accurate method for determining luminance

    NASA Astrophysics Data System (ADS)

    Moore, Kenneth E.; Rykowski, Ronald F.; Gangadhara, Sanjay

    2012-10-01

    Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

  11. Accurate determination of cobalt traces in several biological reference materials.

    PubMed

    Dybczyński, R; Danko, B

    1994-01-01

    A newly devised, very accurate ("definitive") method for the determination of trace amounts of cobalt in biological materials was validated by the analysis of several certified reference materials. The method is based on a combination of neutron activation and selective and quantitative postirradiation isolation of radiocobalt from practically all other radionuclides by ion-exchange and extraction chromatography followed by gamma-ray spectrometric measurement. The significance of criteria that should be fulfilled in order to accept a given result as obtained by the "definitive method" is emphasized. In view of the demonstrated very good accuracy of the method, it is suggested that our values for cobalt content in those reference materials in which it was originally not certified (SRM 1570 spinach, SRM 1571 orchard leaves, SRM 1577 bovine liver, and Czechoslovak bovine liver 12-02-01) might be used as provisional certified values. PMID:7710879

  12. 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.

  13. Accurate theoretical and experimental characterization of optical grating coupler.

    PubMed

    Fesharaki, Faezeh; Hossain, Nadir; Vigne, Sebastien; Chaker, Mohamed; Wu, Ke

    2016-09-01

    Periodic structures, acting as reflectors, filters, and couplers, are a fundamental building block section in many optical devices. In this paper, a three-dimensional simulation of a grating coupler, a well-known periodic structure, is conducted. Guided waves and leakage characteristics of an out-of-plane grating coupler are studied in detail, and its coupling efficiency is examined. Furthermore, a numerical calibration analysis is applied through a commercial software package on the basis of a full-wave finite-element method to calculate the complex propagation constant of the structure and to evaluate the radiation pattern. For experimental evaluation, an optimized grating coupler is fabricated using electron-beam lithography technique and plasma etching. An excellent agreement between simulations and measurements is observed, thereby validating the demonstrated method. PMID:27607706

  14. 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

  15. Accurately Determining the Risks of Rising Sea Level

    NASA Astrophysics Data System (ADS)

    Marbaix, Philippe; Nicholls, Robert J.

    2007-10-01

    With the highest density of people and the greatest concentration of economic activity located in the coastal regions, sea level rise is an important concern as the climate continues to warm. Subsequent flooding may potentially disrupt industries, populations, and livelihoods, particularly in the long term if the climate is not quickly stabilized [McGranahan et al., 2007; Tol et al., 2006]. To help policy makers understand these risks, a more accurate description of hazards posed by rising sea levels is needed at the global scale, even though the impacts in specific regions are better known.

  16. Accurate Determination of Membrane Dynamics with Line-Scan FCS

    PubMed Central

    Ries, Jonas; Chiantia, Salvatore; Schwille, Petra

    2009-01-01

    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. PMID:19254560

  17. Accurate Mass Determinations in Decay Chains with Missing Energy

    SciTech Connect

    Cheng, H.-C; Gunion, John F.; Han Zhenyu; Engelhardt, Dalit; McElrath, Bob

    2008-06-27

    Many beyond the standard model theories include a stable dark matter candidate that yields missing or invisible energy in collider detectors. If observed at the CERN Large Hadron Collider, we must determine if its mass and other properties (and those of its partners) predict the correct dark matter relic density. We give a new procedure for determining its mass with small error.

  18. Accurate mass determinations in decay chains with missing energy.

    PubMed

    Cheng, Hsin-Chia; Engelhardt, Dalit; Gunion, John F; Han, Zhenyu; McElrath, Bob

    2008-06-27

    Many beyond the standard model theories include a stable dark matter candidate that yields missing or invisible energy in collider detectors. If observed at the CERN Large Hadron Collider, we must determine if its mass and other properties (and those of its partners) predict the correct dark matter relic density. We give a new procedure for determining its mass with small error. PMID:18643654

  19. 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...

  20. Accurate Determination of Conformational Transitions in Oligomeric Membrane Proteins

    PubMed Central

    Sanz-Hernández, Máximo; Vostrikov, Vitaly V.; Veglia, Gianluigi; De Simone, Alfonso

    2016-01-01

    The structural dynamics governing collective motions in oligomeric membrane proteins play key roles in vital biomolecular processes at cellular membranes. In this study, we present a structural refinement approach that combines solid-state NMR experiments and molecular simulations to accurately describe concerted conformational transitions identifying the overall structural, dynamical, and topological states of oligomeric membrane proteins. The accuracy of the structural ensembles generated with this method is shown to reach the statistical error limit, and is further demonstrated by correctly reproducing orthogonal NMR data. We demonstrate the accuracy of this approach by characterising the pentameric state of phospholamban, a key player in the regulation of calcium uptake in the sarcoplasmic reticulum, and by probing its dynamical activation upon phosphorylation. Our results underline the importance of using an ensemble approach to characterise the conformational transitions that are often responsible for the biological function of oligomeric membrane protein states. PMID:26975211

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

    PubMed

    Schröder, Heiner; Schwabe, Tobias

    2016-08-15

    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

  2. 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.

  3. Accurate Determination of Torsion and Pure Bending Moment for Viscoelastic Measurements

    NASA Astrophysics Data System (ADS)

    Wang, Yun-Che; Ko, Chih-Chin; Shiau, Li-Ming

    Measurements of time-dependent material properties in the context of linear viscoelasticity, at a given frequency and temperature, require accurate determination of both loading and deformation that are subjected to the testing materials. A pendulum-type viscoelastic spectroscopy is developed to experimentally measure loss tangent and the magnitude of dynamic modulus of solid materials. The mechanical system of the device is based on the behavior of the cantilever beam, and torsion and pure bending moment are generated from the interaction between a permanent magnet and the Helmholtz coils. The strength of the magnetic interactions may be determined with a material with known mechanical properties, such as aluminum 6061T4 alloy. The sensitivity of the torque measurement is on the order of one micro N-m level. With the high accurate torque measurement and deformation detection from a laser-based displacement measurement system, viscoelastic properties of materials can be experimentally measured in different frequency regimes. Sinusoidal driving signals are adopted for measuring complex modulus in the sub-resonant regime, and dc bias driving for creep tests in the low frequency limit. At structural resonant frequencies, the full-width-at-half-maximum (FWHM) method or Lorentzian curve fitting method is adopted to extract material properties. The completion of determining material properties in the wide frequency spectrum may help to identify the deformation mechanisms of the material and to create better models for simulation work.

  4. Applications of accurate isentropic exponent determination for fuel gas measurement

    SciTech Connect

    Pack, D.J.; Edwards, T.J.; Fawcett, D.

    1996-07-01

    This paper discusses the determination and application of the isentropic exponent to the various thermodynamic processes found in a high-pressure natural gas transmission system. Increasing demands for more precise measurement of natural gas, coupled with the need for greater efficiency and accountability of transportation and processing operations, had led to the research and development of gas thermodynamic properties including isentropic exponent. The isentropic exponent has many applications, some of which include: the determination of the expansion factor {epsilon}, for calculation of flow using an orifice or venturi-type meter; the volumetric efficiency in a reciprocating compressor; the determination of the compression head for a centrifugal compressor; the engine power required for the given conditions for a gas compressor; the calculation of discharge temperatures for compressors; and the direct measurement of gas density. As can be appreciated, the application of an incorrect value for the isentropic exponent represents an error in the parameter determined. For large volume gas flows, this can translate into a significant cost penalty.

  5. The Greenhouse Effect - Determination From Accurate Surface Longwave Radiation Measurements

    NASA Astrophysics Data System (ADS)

    Philipona, R.

    Longwave radiation measurements have been drastically improved in recent years. Uncertainty levels down to s2 Wm-2 are realistic and achieved during long-term ´ longwave irradiance measurements. Longwave downward irradiance measurements together with temperature and humidity measurements at the station are used to sepa- rate clear-sky from cloudy-sky situations. Longwave net radiation separated between clear-sky and all-sky situations allows to determine the longwave cloud radiative forc- ing at the station. For clear-sky situations radiative transfer models demonstrate a lin- ear relation between longwave downward radiation and the greenhouse radiative flux. Clear-sky longwave radiation, temperature and humidity for different atmospheres and different altitudes were modeled with the MODTRAN radiative transfer code and compared to longwave radiation, temperature and humidity measured at 4 radiation stations of the Alpine Surface Radiation Budget (ASRB) network at similar altitude and with corresponding atmospheres. At the 11 ASRB stations the clear-sky green- house effect was determined by using clear-sky longwave downward measurements and MODTRAN model calculations. The all-sky greenhouse effect was determined by adding the longwave cloud radiative forcing to the clear-sky greenhouse radiative flux. The altitude dependence of annual and seasonal mean values of the greenhouse effect will be shown for the altitude range of 400 to 3600 meter a.s.l. in the Alps.

  6. Accurate Optical Target Pose Determination for Applications in Aerial Photogrammetry

    NASA Astrophysics Data System (ADS)

    Cucci, D. A.

    2016-06-01

    We propose a new design for an optical coded target based on concentric circles and a position and orientation determination algorithm optimized for high distances compared to the target size. If two ellipses are fitted on the edge pixels corresponding to the outer and inner circles, quasi-analytical methods are known to obtain the coordinates of the projection of the circles center. We show the limits of these methods for quasi-frontal target orientations and in presence of noise and we propose an iterative refinement algorithm based on a geometric invariant. Next, we introduce a closed form, computationally inexpensive, solution to obtain the target position and orientation given the projected circle center and the parameters of the outer circle projection. The viability of the approach is demonstrated based on aerial pictures taken by an UAV from elevations between 10 to 100 m. We obtain a distance RMS below 0.25 % under 50 m and below 1 % under 100 m with a target size of 90 cm, part of which is a deterministic bias introduced by image exposure.

  7. The determination of accurate dipole polarizabilities alpha and gamma for the noble gases

    NASA Technical Reports Server (NTRS)

    Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almloef, Jan

    1989-01-01

    The static dipole polarizabilities alpha and gamma for the noble gases helium through xenon were determined using large flexible one-particle basis sets in conjunction with high-level treatments of electron correlation. The electron correlation methods include single and double excitation coupled-cluster theory (CCSD), an extension of CCSD that includes a perturbational estimate of connected triple excitations, CCSD(T), and second order perturbation theory (MP2). The computed alpha and gamma values are estimated to be accurate to within a few percent. Agreement with experimental data for the static hyperpolarizability gamma is good for neon and xenon, but for argon and krypton the differences are larger than the combined theoretical and experimental uncertainties. Based on our calculations, we suggest that the experimental value of gamma for argon is too low; adjusting this value would bring the experimental value of gamma for krypton into better agreement with our computed result. The MP2 values for the polarizabilities of neon, argon, krypton and zenon are in reasonabe agreement with the CCSD and CCSD(T) values, suggesting that this less expensive method may be useful in studies of polarizabilities for larger systems.

  8. 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. PMID:27393626

  9. 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.

  10. 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.

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

    PubMed

    Kocan, Richard; Dolan, Heather; Hershberger, Paul

    2011-04-01

    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. PMID:21506773

  12. Experimental determination of chlorite dissolution rates

    SciTech Connect

    Rochelle, C.A.; Bateman, K.; MacGregor, R.; Pearce, J.M.; Wetton, P.D.; Savage, D.

    1995-12-31

    Current concepts of the geological disposal of low- and intermediate-level radioactive wastes in the UK envisage the construction of a mined facility (incorporating cementitious engineered barriers) in chlorite-bearing rocks. To model accurately the fluid-rock reactions within the disturbed zone surrounding a repository requires functions that describe mineral dissolution kinetics under pH conditions that vary from near neutral to highly alkaline. Therefore, an experimental study to determine the dissolution rates of Fe-rich chlorite has been undertaken as part of the Nirex Safety Assessment Research Program. Four experiments have been carried out at 25 C and four at 70 C, both sets using a range of NaCl/NaOH solutions of differing pH (of nominal pH 9.0, 10.3, 11.6 and 13.0 [at 25 C]). Dissolution rates have been calculated and were found to increase with increasing pH and temperature. However, increased pH resulted in non-stoichiometric dissolution possibly due to preferential dissolution of part of the chlorite structure relative to another, or reprecipitation of some elements as thin hydroxide or oxyhydroxide surface coatings on the chlorite. These results also show that chlorite dissolution is appreciably slower than that of albite and quartz at both 25 and 70 C, but slightly faster than that of muscovite at 70 C.

  13. 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).

  14. Fast and accurate determination of the Wigner rotation matrices in the fast multipole method.

    PubMed

    Dachsel, Holger

    2006-04-14

    In the rotation based fast multipole method the accurate determination of the Wigner rotation matrices is essential. The combination of two recurrence relations and the control of the error accumulations allow a very precise determination of the Wigner rotation matrices. The recurrence formulas are simple, efficient, and numerically stable. The advantages over other recursions are documented. PMID:16626188

  15. 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 ...

  16. 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}.

  17. Turtle utricle dynamic behavior using a combined anatomically accurate model and experimentally measured hair bundle stiffness

    PubMed Central

    Davis, J.L.; Grant, J.W.

    2014-01-01

    Anatomically correct turtle utricle geometry was incorporated into two finite element models. The geometrically accurate model included appropriately shaped macular surface and otoconial layer, compact gel and column filament (or shear) layer thicknesses and thickness distributions. The first model included a shear layer where the effects of hair bundle stiffness was included as part of the shear layer modulus. This solid model’s undamped natural frequency was matched to an experimentally measured value. This frequency match established a realistic value of the effective shear layer Young’s modulus of 16 Pascals. We feel this is the most accurate prediction of this shear layer modulus and fits with other estimates (Kondrachuk, 2001b). The second model incorporated only beam elements in the shear layer to represent hair cell bundle stiffness. The beam element stiffness’s were further distributed to represent their location on the neuroepithelial surface. Experimentally measured striola hair cell bundles mean stiffness values were used in the striolar region and the mean extrastriola hair cell bundles stiffness values were used in this region. The results from this second model indicated that hair cell bundle stiffness contributes approximately 40% to the overall stiffness of the shear layer– hair cell bundle complex. This analysis shows that high mass saccules, in general, achieve high gain at the sacrifice of frequency bandwidth. We propose the mechanism by which this can be achieved is through increase the otoconial layer mass. The theoretical difference in gain (deflection per acceleration) is shown for saccules with large otoconial layer mass relative to saccules and utricles with small otoconial layer mass. Also discussed is the necessity of these high mass saccules to increase their overall system shear layer stiffness. Undamped natural frequencies and mode shapes for these sensors are shown. PMID:25445820

  18. 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

  19. 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.

  20. Determination of accurate dissociation limits and interatomic interactions at large internuclear distances

    NASA Astrophysics Data System (ADS)

    Stwalley, W. C.; Verma, K. K.; Rajaei-Rizi, A.; Bahns, J. T.; Harding, D. R.

    This paper illustrates (using the molecules LiH, Li2 and Na2) how laser-induced fluorescence can be used to greatly expand the range of observed vibrational levels in ground electronic states. This expanded vibrational range leads to the determination of virtually the full well of the potential energy curve. This also leads to improved determination of the dissociation limit and serves as a severe test for highly accurate ab initio calculations now available for many small molecules.

  1. Determination of accurate dissociation limits and interatomic interactions at large internuclear distances

    NASA Technical Reports Server (NTRS)

    Stwalley, W. C.; Verma, K. K.; Rajaei-Rizi, A.; Bahns, J. T.; Harding, D. R.

    1982-01-01

    This paper illustrates (using the molecules LiH, Li2 and Na2) how laser-induced fluorescence can be used to greatly expand the range of observed vibrational levels in ground electronic states. This expanded vibrational range leads to the determination of virtually the full well of the potential energy curve. This also leads to improved determination of the dissociation limit and serves as a severe test for highly accurate ab initio calculations now available for many small molecules.

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

    PubMed

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

    2015-07-01

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

  3. 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. PMID:23623796

  4. 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. PMID:24411140

  5. 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.

  6. Accurate determination of solid and liquid dispersions from spectra channeled with the Fabry-Perot interferometer.

    PubMed

    Khashan, M A; Nassif, A Y

    1997-09-20

    The band spacing of the fringes of equal chromatic order of a thin Fabry-Perot interferometer is compared when this interferometer contains air, a solid, or a liquid. This comparison enables the dispersion of the group velocity of light in these media to be known accurately to 2.4 parts in one thousand. The Sellmeier dispersion function is used to deduce the refractive indices with the same degree of accuracy. The order-transformation method is used to find the exact order values from the roughly known optical thickness. The exact order values for air and the sample are used to find the refractive index accurately to approximately 3 x 10(-5). A least-squares fitting of the accurate experimental data to the Sellmeier dispersion function enables the coefficients of the latter to be more precisely defined for solids such as glass and mica and for liquids such as glycerin and distilled water. The atomic parameters such as the density of states and the absorption wavelengths in the ultraviolet region of the spectrum for the given samples are deduced from the more precisely found Sellmeier coefficients. PMID:18259554

  7. 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.

  8. 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.

  9. Accurate determination of the magnetic anisotropy in cluster-assembled nanostructures

    NASA Astrophysics Data System (ADS)

    Tamion, Alexandre; Hillenkamp, Matthias; Tournus, Florent; Bonet, Edgar; Dupuis, Véronique

    2009-08-01

    The simultaneous triple adjustment of experimental magnetization curves under different conditions is shown to allow the unambiguous and consistent determination of both the magnetic particle size distribution and anisotropy for granular nanostructures of Co clusters embedded in protective matrices. The importance of interface effects resulting in magnetically dead layers is demonstrated.

  10. 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

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

    PubMed

    Stewart, W C L; Hager, V R

    2016-08-01

    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

  12. The Development of a Digital Processing System for Accurate Range Determinations. [for Teleoperator Maneuvering Systems

    NASA Technical Reports Server (NTRS)

    Pujol, A., Jr.

    1983-01-01

    The development of an accurate close range (from 0.0 meters to 30.0 meters) radar system for Teleoperator Maneuvering Systems (TMS) is discussed. The system under investigation is a digital processor that converts incoming signals from the radar system into their related frequency spectra. Identification will be attempted by correlating spectral characteristics with accurate range determinataions. The system will utilize an analog to digital converter for sampling and converting the signal from the radar system into 16-bit digital words (two bytes) for RAM storage, data manipulations, and computations. To remove unwanted frequency components the data will be retrieved from RAM and digitally filtered using large scale integration (LSI) circuits. Filtering will be performed by a biquadratic routine within the chip which carries out the required filter algorithm. For conversion to a frequency spectrum the filtered data will be processed by a Fast Fourier Transform chip. Analysis and identification of spectral characteristics for accurate range determinations will be made by microcomputer computations.

  13. Accurate determination of quantity of material in thin films by Rutherford backscattering spectrometry.

    PubMed

    Jeynes, C; Barradas, N P; Szilágyi, E

    2012-07-17

    Ion beam analysis (IBA) is a cluster of techniques including Rutherford and non-Rutherford backscattering spectrometry and particle-induced X-ray emission (PIXE). Recently, the ability to treat multiple IBA techniques (including PIXE) self-consistently has been demonstrated. The utility of IBA for accurately depth profiling thin films is critically reviewed. As an important example of IBA, three laboratories have independently measured a silicon sample implanted with a fluence of nominally 5 × 10(15) As/cm(2) at an unprecedented absolute accuracy. Using 1.5 MeV (4)He(+) Rutherford backscattering spectrometry (RBS), each lab has demonstrated a combined standard uncertainty around 1% (coverage factor k = 1) traceable to an Sb-implanted certified reference material through the silicon electronic stopping power. The uncertainty budget shows that this accuracy is dominated by the knowledge of the electronic stopping, but that special care must also be taken to accurately determine the electronic gain of the detection system and other parameters. This RBS method is quite general and can be used routinely to accurately validate ion implanter charge collection systems, to certify SIMS standards, and for other applications. The generality of application of such methods in IBA is emphasized: if RBS and PIXE data are analysed self-consistently then the resulting depth profile inherits the accuracy and depth resolution of RBS and the sensitivity and elemental discrimination of PIXE. PMID:22681761

  14. A calibration-independent method for accurate complex permittivity determination of liquid materials

    SciTech Connect

    Hasar, U. C.

    2008-08-15

    This note presents a calibration-independent method for accurate complex permittivity determination of liquid materials. There are two main advantages of the proposed method over those in the literature, which require measurements of two cells with different lengths loaded by the same liquid material. First, it eliminates any inhomogeneity or impurity present in the second sample and decreases the uncertainty in sample thickness. Second, it removes the undesired impacts of measurement plane deterioration on measurements of liquid materials. For validation of the proposed method, we measure the complex permittivity of distilled water and compare its extracted permittivity with the theoretical datum obtained from the Debye equation.

  15. 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.

  16. 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.

  17. [The determinant role of an accurate medicosocial approach in the prognosis of pediatric blood diseases].

    PubMed

    Toppet, M

    2005-01-01

    The care of infancy and childhood blood diseases implies a comprehensive medicosocial approach. This is a prerequisite for regular follow-up, for satisfactory compliance to treatment and for optimal patient's quality of life. Different modalities of medicosocial approach have been developed in the pediatric department (firstly in the Hospital Saint Pierre and than in the Children's University Hospital HUDERF). The drastic importance of a recent reform of the increased family allowances is briefly presented. The author underlines the determinant role of an accurate global approach, in which the patient and the family are surrounded by a multidisciplinary team, including social workers. PMID:16454232

  18. Accurate age determinations of several nearby open clusters containing magnetic Ap stars

    NASA Astrophysics Data System (ADS)

    Silaj, J.; Landstreet, J. D.

    2014-06-01

    Context. To study the time evolution of magnetic fields, chemical abundance peculiarities, and other characteristics of magnetic Ap and Bp stars during their main sequence lives, a sample of these stars in open clusters has been obtained, as such stars can be assumed to have the same ages as the clusters to which they belong. However, in exploring age determinations in the literature, we find a large dispersion among different age determinations, even for bright, nearby clusters. Aims: Our aim is to obtain ages that are as accurate as possible for the seven nearby open clusters α Per, Coma Ber, IC 2602, NGC 2232, NGC 2451A, NGC 2516, and NGC 6475, each of which contains at least one magnetic Ap or Bp star. Simultaneously, we test the current calibrations of Te and luminosity for the Ap/Bp star members, and identify clearly blue stragglers in the clusters studied. Methods: We explore the possibility that isochrone fitting in the theoretical Hertzsprung-Russell diagram (i.e. log (L/L⊙) vs. log Te), rather than in the conventional colour-magnitude diagram, can provide more precise and accurate cluster ages, with well-defined uncertainties. Results: Well-defined ages are found for all the clusters studied. For the nearby clusters studied, the derived ages are not very sensitive to the small uncertainties in distance, reddening, membership, metallicity, or choice of isochrones. Our age determinations are all within the range of previously determined values, but the associated uncertainties are considerably smaller than the spread in recent age determinations from the literature. Furthermore, examination of proper motions and HR diagrams confirms that the Ap stars identified in these clusters are members, and that the presently accepted temperature scale and bolometric corrections for Ap stars are approximately correct. We show that in these theoretical HR diagrams blue stragglers are particularly easy to identify. Conclusions: Constructing the theoretical HR diagram

  19. 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.

  20. Accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography.

    PubMed

    Zhang, Shu-Xin; Chai, Xin-Sheng; He, Liang

    2016-09-16

    This work reports on a method for the accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography (HS-GC) method. The method was based the HS-GC measurement of water vapor on a set closed vials containing in a given amount pulp with different amounts of water addition, from under-saturation to over-saturation. By plotting the equilibrated water vapor signal vs. the amount of water added in pulp, two different trend lines can be observed, in which the transition of the lines corresponds to fiber water-retaining capability. The results showed that the HS-GC method has good measurement precision (much better than the reference method) and good accuracy. The present method can be also used for determining pulp fiber water-retaining capability at the process temperatures in both laboratory research and mill applications. PMID:27554029

  1. 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

  2. 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. PMID:25404762

  3. 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. PMID:25607375

  4. A finite element technique for accurate determination of interfacial adhesion force in MEMS using electrostatic actuation

    NASA Astrophysics Data System (ADS)

    Shavezipur, M.; Li, G. H.; Laboriante, I.; Gou, W. J.; Carraro, C.; Maboudian, R.

    2011-11-01

    This paper reports on accurate analysis of adhesion force between polysilicon-polysilicon surfaces in micro-/nanoelectromechanical systems (M/NEMS). The measurement is carried out using double-clamped beams. Electrostatic actuation and structural restoring force are exploited to respectively initiate and terminate the contact between the two surfaces under investigation. The adhesion force is obtained by balancing the electrostatic and mechanical forces acting on the beam just before the separation of the two surfaces. Different finite element models are developed to simulate the coupled-field multiphysics problem. The effects of fringing field in the electrostatic domain and geometric nonlinearity and residual stress in the structural domain are taken into consideration. Moreover, the beam stiffness is directly obtained for the case of combined loading (electrostatic and adhesion). Therefore, the overall electrostatic and structural forces used to extract the actual adhesion force from measured data are determined with high accuracy leading to accurate values for the adhesion force. The finite element simulations presented in this paper are not limited to adhesion force measurement and can be used to design or characterize electrostatically actuated devices such as MEM tunable capacitors and micromirrors, RF switches and M/NEM relays.

  5. Accurate determination of the valence band edge in hard x-ray photoemission spectra using GW theory

    NASA Astrophysics Data System (ADS)

    Lischner, Johannes; Nemšák, Slavomír; Conti, Giuseppina; Gloskovskii, Andrei; Pálsson, Gunnar Karl; Schneider, Claus M.; Drube, Wolfgang; Louie, Steven G.; Fadley, Charles

    2016-04-01

    We introduce a new method for determining accurate values of the valence-band maximum in x-ray photoemission spectra. Specifically, we align the sharpest peak in the valence-band region of the experimental spectrum with the corresponding feature of a theoretical valence-band density of states curve from ab initio GW theory calculations. This method is particularly useful for soft and hard x-ray photoemission studies of materials with a mixture of valence-band characters, where strong matrix element effects can render standard methods for extracting the valence-band maximum unreliable. We apply our method to hydrogen-terminated boron-doped diamond, which is a promising substrate material for novel solar cell devices. By carrying out photoemission experiments with variable light polarizations, we verify the accuracy of our analysis and the general validity of the method.

  6. Determination of the diffuser reference plane for accurate illuminance responsivity calibrations

    SciTech Connect

    Hovila, Jari; Mustonen, Maria; Kaerhae, Petri; Ikonen, Erkki

    2005-10-01

    It is difficult to predict where the effective measurement plane is situated with dome-shaped diffusers often used in commercial photometers and radiometers. Insufficient knowledge of this plane could lead to large systematic errors in calibration of the illuminance responsivity of photometers. We propose a method that can be used to determine this reference plane accurately, based on the inverse-square law between the measured signal and the distance from the source. The method is demonstrated with three commercial photometers with dome-shaped diffusers of different geometries. By taking into account the measured shifts of the reference planes (5.0{+-}0.5 mm, 7.8{+-}0.3 mm, and 8.5{+-}0.7 mm), we reduced the systematic measurement errors up to 2% to statistical uncertainty components at the level of 0.2%.

  7. 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. PMID:25798300

  8. 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.

  9. 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.

  10. Accurate NMR determination of C-H or N-H distances for unlabeled molecules.

    PubMed

    Nishiyama, Y; Malon, M; Potrzebowski, M J; Paluch, P; Amoureux, J P

    2016-02-01

    Cross-Polarization with Variable Contact-time (CP-VC) is very efficient at ultra-fast MAS (νR ≥ 60 kHz) to measure accurately the dipolar interactions corresponding to C-H or N-H short distances, which are very useful for resonance assignment and for analysis of dynamics. Here, we demonstrate the CP-VC experiment with (1)H detection. In the case of C-H distances, we compare the CP-VC signals with direct ((13)C) and indirect ((1)H) detection and find that the latter allows a S/N gain of ca. 2.5, which means a gain of ca. 6 in experimental time. The main powerful characteristics of CP-VC methods are related to the ultra-fast spinning speed and to the fact that most of the time only the value of the dipolar peak separation has to be used to obtain the information. As a result, CP-VC methods are: (i) easy to set up and to use, and robust with respect to (ii) rf-inhomogeneity thus allowing the use of full rotor samples, (iii) rf mismatch, and (iv) offsets and chemical shift anisotropies. It must be noted that the CP-VC 2D method with indirect (1)H detection requires the proton resolution and is thus mainly applicable to small or perdeuterated molecules. We also show that an analysis of the dynamics can even be performed, with a reasonable experimental time, on unlabeled samples with (13)C or even (15)N natural abundance. PMID:26169913

  11. Spreading of liquid droplets on cylindrical surfaces: Accurate determination of contact angle

    NASA Astrophysics Data System (ADS)

    Wagner, H. D.

    1990-02-01

    The characterization of the physicochemical nature of interfaces is a key problem in the field of advanced fibrous composites. The macroscopic regime contact angle, which reflects the energetics of wetting at the solid-liquid interface, is difficult to measure by usual methods in the case of very thin cylindrical fibers, but it may be calculated from the shape of a liquid droplet spread onto a cylindrical monofilament using a method developed by Yamaki and Katayama [J. Appl. Polym. Sci. 19, 2897 (1975)], and B. J. Carroll [J. Coll. Interf. Sci. 57, 488 (1976)]. Unfortunately, measurements of the contact angle based on this method are, so far, unable to provide an accuracy of better than about 5°. In the present article two simple extensions of the method of Yamaki and Katayama and Carroll, are presented, from which highly accurate values of the contact angle may be obtained. This is demonstrated experimentally from the spreading of glycerol droplets on carbon fibers and epoxy droplets on aramid fibers.

  12. 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.

  13. An accurate and nondestructive GC method for determination of cocaine on US paper currency.

    PubMed

    Zuo, Yuegang; Zhang, Kai; Wu, Jingping; Rego, Christopher; Fritz, John

    2008-07-01

    The presence of cocaine on US paper currency has been known for a long time. Banknotes become contaminated during the exchange, storage, and abuse of cocaine. The analysis of cocaine on various denominations of US banknotes in the general circulation can provide law enforcement circles and forensic epidemiologists objective and timely information on epidemiology of illicit drug use and on how to differentiate money contaminated in the general circulation from banknotes used in drug transaction. A simple, nondestructive, and accurate capillary gas chromatographic method has been developed for the determination of cocaine on various denominations of US banknotes in this study. The method comprises a fast ultrasonic extraction using water as a solvent followed by a SPE cleanup process with a C(18) cartridge and capillary GC separation, identification, and quantification. This nondestructive analytical method has been successfully applied to determine the cocaine contamination in US paper currency of all denominations. Standard calibration curve was linear over the concentration range from the LOQ (2.00 ng/mL) to 100 microg/mL and the RSD less than 2.0%. Cocaine was detected in 67% of the circulated banknotes collected in Southeastern Massachusetts in amounts ranging from approximately 2 ng to 49.4 microg per note. On average, $5, 10, 20, and 50 denominations contain higher amounts of cocaine than $1 and 100 denominations of US banknotes. PMID:18646272

  14. Optical coherence tomography enables accurate measurement of equine cartilage thickness for determination of speed of sound.

    PubMed

    Puhakka, Pia H; Te Moller, Nikae C R; Tanska, Petri; Saarakkala, Simo; Tiitu, Virpi; Korhonen, Rami K; Brommer, Harold; Virén, Tuomas; Jurvelin, Jukka S; Töyräs, Juha

    2016-08-01

    Background and purpose - Arthroscopic estimation of articular cartilage thickness is important for scoring of lesion severity, and measurement of cartilage speed of sound (SOS)-a sensitive index of changes in cartilage composition. We investigated the accuracy of optical coherence tomography (OCT) in measurements of cartilage thickness and determined SOS by combining OCT thickness and ultrasound (US) time-of-flight (TOF) measurements. Material and methods - Cartilage thickness measurements from OCT and microscopy images of 94 equine osteochondral samples were compared. Then, SOS in cartilage was determined using simultaneous OCT thickness and US TOF measurements. SOS was then compared with the compositional, structural, and mechanical properties of cartilage. Results - Measurements of non-calcified cartilage thickness using OCT and microscopy were significantly correlated (ρ = 0.92; p < 0.001). With calcified cartilage included, the correlation was ρ = 0.85 (p < 0.001). The mean cartilage SOS (1,636 m/s) was in agreement with the literature. However, SOS and the other properties of cartilage lacked any statistically significant correlation. Interpretation - OCT can give an accurate measurement of articular cartilage thickness. Although SOS measurements lacked accuracy in thin equine cartilage, the concept of SOS measurement using OCT appears promising. PMID:27164159

  15. A method for accurate determination of terminal sequences of viral genomic RNA.

    PubMed

    Weng, Z; Xiong, Z

    1995-09-01

    A combination of ligation-anchored PCR and anchored cDNA cloning techniques were used to clone the termini of the saguaro cactus virus (SCV) RNA genome. The terminal sequences of the viral genome were subsequently determined from the clones. The 5' terminus was cloned by ligation-anchored PCR, whereas the 3' terminus was obtained by a technique we term anchored cDNA cloning. In anchored cDNA cloning, an anchor oligonucleotide was prepared by phosphorylation at the 5' end, followed by addition of a dideoxynucleotide at the 3' end to block the free hydroxyl group. The 5' end of the anchor was subsequently ligated to the 3' end of SCV RNA. The anchor-ligated, chimerical viral RNA was then reverse-transcribed into cDNA using a primer complementary to the anchor. The cDNA containing the complete 3'-terminal sequence was converted into ds-cDNA, cloned, and sequenced. Two restriction sites, one within the viral sequence and one within the primer sequence, were used to facilitate cloning. The combination of these techniques proved to be an easy and accurate way to determine the terminal sequences of SCV RNA genome and should be applicable to any other RNA molecules with unknown terminal sequences. PMID:9132274

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry

    2015-06-01

    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 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 met. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady 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 brief review will be presented on systematic errors in shock wave data from common experimental techniques for fluids, elastic-plastic solids, materials with negative volume phase transitions, glass and ceramic materials, and high explosives. Issues related to time scales of experiments and quasi-steady flow will also be presented.

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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 Tc = 1.3128 ± 0.0016, ρc = 0.316 ± 0.004, and pc = 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 ≤ ρt ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using rcut = 3.5σ yield Tc and pc that are higher by 0.2% and 1.4% than simulations with rcut = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that rcut = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard-core square-well particles with various ranges of the

  20. 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

  1. 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

  2. Experimental determination of core electron deformation in diamond.

    PubMed

    Bindzus, Niels; Straasø, Tine; Wahlberg, Nanna; Becker, Jacob; Bjerg, Lasse; Lock, Nina; Dippel, Ann Christin; Iversen, Bo B

    2014-01-01

    Synchrotron powder X-ray diffraction data are used to determine the core electron deformation of diamond. Core shell contraction inherently linked to covalent bond formation is observed in close correspondence with theoretical predictions. Accordingly, a precise and physically sound reconstruction of the electron density in diamond necessitates the use of an extended multipolar model, which abandons the assumption of an inert core. The present investigation is facilitated by negligible model bias in the extraction of structure factors, which is accomplished by simultaneous multipolar and Rietveld refinement accurately determining an atomic displacement parameter (ADP) of 0.00181 (1) Å(2). The deconvolution of thermal motion is a critical step in experimental core electron polarization studies, and for diamond it is imperative to exploit the monatomic crystal structure by implementing Wilson plots in determination of the ADP. This empowers the electron-density analysis to precisely administer both the deconvolution of thermal motion and the employment of the extended multipolar model on an experimental basis. PMID:24419169

  3. 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.

  4. 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. PMID:27370490

  5. Can scintillation detectors with low spectral resolution accurately determine radionuclides content of building materials?

    PubMed

    Kovler, K; Prilutskiy, Z; Antropov, S; Antropova, N; Bozhko, V; Alfassi, Z B; Lavi, N

    2013-07-01

    The current paper makes an attempt to check whether the scintillation NaI(Tl) detectors, in spite of their poor energy resolution, can determine accurately the content of NORM in building materials. The activity concentrations of natural radionuclides were measured using two types of detectors: (a) NaI(Tl) spectrometer equipped with the special software based on the matrix method of least squares, and (b) high-purity germanium spectrometer. Synthetic compositions with activity concentrations varying in a wide range, from 1/5 to 5 times median activity concentrations of the natural radionuclides available in the earth crust and the samples of popular building materials, such as concrete, pumice and gypsum, were tested, while the density of the tested samples changed in a wide range (from 860 up to 2,410 kg/m(3)). The results obtained in the NaI(Tl) system were similar to those obtained with the HPGe spectrometer, mostly within the uncertainty range. This comparison shows that scintillation spectrometers equipped with a special software aimed to compensate for the lower spectral resolution of NaI(Tl) detectors can be successfully used for the radiation control of mass construction products. PMID:23542118

  6. 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.

  7. 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.

  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. Dual-beam interferometer for the accurate determination of surface-wave velocity.

    PubMed

    McKie, A D; Wagner, J W; Spicer, J B; Deaton, J B

    1991-10-01

    A novel dual-beam interferometer has been designed and constructed that enables two beams from a He-Ne laser to probe remotely the surface of a material. The separation of the two He-Ne beams is adjustable in the 15-to- 40-mm range with a spatial resolution of 2 microm. Surface-acoustic-wave measurements have been performed with two different probe separations so that the travel time for the surface waves over a known distance can be determined accurately. With the aid of autocorrelation algorithms, the Rayleigh pulse velocity on 7075-T651 aluminum has been measured to be 2888 +/- 4 m/s. The current precision of the system is limited mainly by the 10-ns sampling rate of the digital oscilloscope used. Rayleigh pulse interactions with a surface-breaking slot, machined to a nominal depth of 0.5 mm, have also been examined and the depth estimated ultrasonically to be 0.49 +/- 0.02 mm. The system may also provide a technique for direct quantitative studies of surface-wave attenuation. PMID:20706500

  10. RES-TOCSY: A facile approach for accurate determination of magnitudes, and relative signs of nJHF

    NASA Astrophysics Data System (ADS)

    Lokesh; Chaudhari, Sachin R.; Suryaprakash, N.

    2014-05-01

    The RES-TOCSY experiment for accurate determination of heteronuclear nJHF is reported. The main feature of the proposed technique is the accurate measurement of magnitudes of heteronuclear couplings from the displacement of cross sections of the 2D spectrum and their relative signs from the slopes of their displacement vectors. The experiment is highly advantageous as the couplings of smaller magnitudes hidden within line widths could also be accurately determined, and also in situations when the spectrum does not display any coupling fine structures. The efficient utility of the developed pulse sequence is unambiguously established on fluorine containing aromatic and aliphatic molecules.

  11. Optimizing photon fluence measurements for the accurate determination of detective quantum efficiency

    NASA Astrophysics Data System (ADS)

    Wong, Molly; Zhang, Da; Rong, John; Wu, Xizeng; Liu, Hong

    2009-10-01

    Our goal was to evaluate the error contributed by photon fluence measurements to the detective quantum efficiency (DQE) of an x-ray imaging system. The investigation consisted of separate error analyses for the exposure and spectrum measurements that determine the photon fluence. Methods were developed for each to determine the number of measurements required to achieve an acceptable error. A new method for calculating the magnification factor in the exposure measurements was presented and compared to the existing method. The new method not only produces much lower error at small source-to-image distances (SIDs) such as clinical systems, but is also independent of SID. The exposure and spectra results were combined to determine the photon fluence error contribution to the DQE of 4%. The error in this study is small because the measurements resulted from precisely controlled experimental procedures designed to minimize the error. However, these procedures are difficult to follow in clinical environments, and application of this method on clinical systems could therefore provide important insight into error reduction. This investigation was focused on the error in the photon fluence contribution to the DQE, but the error analysis method can easily be extended to a wide range of applications.

  12. Experimental determination of airplane mass and inertial characteristics

    NASA Technical Reports Server (NTRS)

    Wolowicz, C. H.; Yancey, R. B.

    1974-01-01

    Current practices are evaluated for experimentally determining airplane center of gravity, moments of inertia, and products of inertia. The techniques discussed are applicable to bodies other than airplanes. In pitching- and rolling-moment-of-inertia investigations with the airplane mounted on and pivoted about knife edges, the nonlinear spring moments that occur at large amplitudes of oscillation can be eliminated by using the proper spring configuration. The single-point suspension double-pendulum technique for obtaining yawing moments of inertia, products of inertia, and the inclination of the principal axis provides accurate results from yaw-mode oscillation data, provided that the sway-mode effects are minimized by proper suspension rig design. Rocking-mode effects in the data can be isolated.

  13. 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).

  14. Nonlinear Optical Properties of Fluorescent Dyes Allow for Accurate Determination of Their Molecular Orientations in Phospholipid Membranes.

    PubMed

    Timr, Štěpán; Brabec, Jiří; Bondar, Alexey; Ryba, Tomáš; Železný, Miloš; Lazar, Josef; Jungwirth, Pavel

    2015-07-30

    Several methods based on single- and two-photon fluorescence detected linear dichroism have recently been used to determine the orientational distributions of fluorescent dyes in lipid membranes. However, these determinations relied on simplified descriptions of nonlinear anisotropic properties of the dye molecules, using a transition dipole-moment-like vector instead of an absorptivity tensor. To investigate the validity of the vector approximation, we have now carried out a combination of computer simulations and polarization microscopy experiments on two representative fluorescent dyes (DiI and F2N12S) embedded in aqueous phosphatidylcholine bilayers. Our results indicate that a simplified vector-like treatment of the two-photon transition tensor is applicable for molecular geometries sampled in the membrane at ambient conditions. Furthermore, our results allow evaluation of several distinct polarization microscopy techniques. In combination, our results point to a robust and accurate experimental and computational treatment of orientational distributions of DiI, F2N12S, and related dyes (including Cy3, Cy5, and others), with implications to monitoring physiologically relevant processes in cellular membranes in a novel way. PMID:26146848

  15. A new, fast and accurate spectrophotometric method for the determination of the optical constants of arbitrary absorptance thin films from a single transmittance curve: application to dielectric materials

    NASA Astrophysics Data System (ADS)

    Desforges, Jean; Deschamps, Clément; Gauvin, Serge

    2015-08-01

    The determination of the complex refractive index of thin films usually requires the highest accuracy. In this paper, we report on a new and accurate method based on a spectral rectifying process of a single transmittance curve. The agreements with simulated and real experimental data show the helpfulness of the method. The case of materials having arbitrary absorption bands at midpoint in spectral range, such as pigments in guest-host polymers, is also encompassed by this method.

  16. 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

  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. 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

  19. 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

  20. Technique for determination of accurate heat capacities of volatile, powdered, or air-sensitive samples using relaxation calorimetry

    NASA Astrophysics Data System (ADS)

    Marriott, Robert A.; Stancescu, Maria; Kennedy, Catherine A.; White, Mary Anne

    2006-09-01

    We introduce a four-step technique for the accurate determination of the heat capacity of volatile or air-sensitive samples using relaxation calorimetry. The samples are encapsulated in a hermetically sealed differential scanning calorimetry pan, in which there is an internal layer of Apiezon N grease to assist thermal relaxation. Using the Quantum Design physical property measurement system to investigate benzoic acid and copper standards, we find that this method can lead to heat capacity determinations accurate to ±2% over the temperature range of 1-300K, even for very small samples (e.g., <10mg and contributing ca. 20% to the total heat capacity).

  1. Accurate determination of relative metatarsal protrusion with a small intermetatarsal angle: a novel simplified method.

    PubMed

    Osher, Lawrence; Blazer, Marie Mantini; Buck, Stacie; Biernacki, Tomasz

    2014-01-01

    Several published studies have explained in detail how to measure relative metatarsal protrusion on the plain film anteroposterior pedal radiograph. These studies have demonstrated the utility of relative metatarsal protrusion measurement in that it correlates with distal forefoot deformity or pathologic features. The method currently preferred by practitioners in podiatric medicine and surgery often presents one with the daunting challenge of obtaining an accurate measurement when the intermetatarsal 1-2 angle is small. The present study illustrates a novel mathematical solution to this problem that is simple to master, relatively quick to perform, and yields accurate results. Our method was tested and proven by 4 trained observers with varying degrees of clinical skill who independently measured the same 10 radiographs. PMID:24933656

  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. 45 CFR 261.64 - How will we determine whether a State's work verification procedures ensure an accurate work...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 2 2014-10-01 2012-10-01 true How will we determine whether a State's work verification procedures ensure an accurate work participation measurement? 261.64 Section 261.64 Public Welfare Regulations Relating to Public Welfare OFFICE OF FAMILY ASSISTANCE (ASSISTANCE PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES,...

  4. 45 CFR 261.64 - How will we determine whether a State's work verification procedures ensure an accurate work...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false How will we determine whether a State's work verification procedures ensure an accurate work participation measurement? 261.64 Section 261.64 Public Welfare Regulations Relating to Public Welfare OFFICE OF FAMILY ASSISTANCE (ASSISTANCE PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES,...

  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. 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.)

  7. Molecular Diffusion Coefficients: Experimental Determination and Demonstration.

    ERIC Educational Resources Information Center

    Fate, Gwendolyn; Lynn, David G.

    1990-01-01

    Presented are laboratory methods which allow the demonstration and determination of the diffusion coefficients of compounds ranging in size from water to small proteins. Included are the procedures involving the use of a spectrometer, UV cell, triterated agar, and oxygen diffusion. Results including quantification are described. (CW)

  8. Accurate determination of selected pesticides in soya beans by liquid chromatography coupled to isotope dilution mass spectrometry.

    PubMed

    Huertas Pérez, J F; Sejerøe-Olsen, B; Fernández Alba, A R; Schimmel, H; Dabrio, M

    2015-05-01

    A sensitive, accurate and simple liquid chromatography coupled with mass spectrometry method for the determination of 10 selected pesticides in soya beans has been developed and validated. The method is intended for use during the characterization of selected pesticides in a reference material. In this process, high accuracy and appropriate uncertainty levels associated to the analytical measurements are of utmost importance. The analytical procedure is based on sample extraction by the use of a modified QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction and subsequent clean-up of the extract with C18, PSA and Florisil. Analytes were separated on a C18 column using gradient elution with water-methanol/2.5 mM ammonium acetate mobile phase, and finally identified and quantified by triple quadrupole mass spectrometry in the multiple reaction monitoring mode (MRM). Reliable and accurate quantification of the analytes was achieved by means of stable isotope-labelled analogues employed as internal standards (IS) and calibration with pure substance solutions containing both, the isotopically labelled and native compounds. Exceptions were made for thiodicarb and malaoxon where the isotopically labelled congeners were not commercially available at the time of analysis. For the quantification of those compounds methomyl-(13)C2(15)N and malathion-D10 were used respectively. The method was validated according to the general principles covered by DG SANCO guidelines. However, validation criteria were set more stringently. Mean recoveries were in the range of 86-103% with RSDs lower than 8.1%. Repeatability and intermediate precision were in the range of 3.9-7.6% and 1.9-8.7% respectively. LODs were theoretically estimated and experimentally confirmed to be in the range 0.001-0.005 mg kg(-1) in the matrix, while LOQs established as the lowest spiking mass fractionation level were in the range 0.01-0.05 mg kg(-1). The method reliably identifies and quantifies the

  9. The experimental determination of coal models

    SciTech Connect

    Bollinger, K.; Snowden, H.

    1983-06-01

    This paper describes the experimental measurement of coal-mill transfer functions at a 380 Mw steam turbine generator of TransAlta Utilities in Canada. Measurement equipment was used that estimated the parameters of the transfer functions from digitized transients obtained during on-site tests. These preliminary tests were part of a sequence of tests that were undertaken to evaluate the use of feedforward control to maintain the output temperature of the coal-air mixture at a fixed level. The measurement technique used to obtain the coal-mill transfer functions utilizes Least Squares Parameter Estimation (LSPE) concepts. The microprocessor-based system with the LSPE algorithm enabled the parameters to be obtained while the coal-mill was operating online. The transfer functions obtained during these field tests allowed feedforward controllers to be designed that gave improved performance of the coal-mill.

  10. Template tailoring: Accurate determination of heterozygous alleles using peptide nucleic acid and dideoxyNTP

    PubMed Central

    Tariq, Muhammad Akram; Pourmand, Nader

    2010-01-01

    Measurement of the length of DNA fragments plays a pivotal role in genetic mapping, disease diagnostics, human identification and forensic applications. PCR followed by electrophoresis is used for DNA length measurement of STRs, a process that requires labeled primers and allelic ladders as standards to avoid machine error. Sequencing-based approaches can be used for STR analysis to eliminate the requirement of labeled primers and allelic ladder. However, the limiting factor with this approach is unsynchronized polymerization in heterozygous sample analysis, in which alleles with different lengths can lead to imbalanced heterozygote peak height ratios. We have developed a rapid DNA length measurement method using peptide nucleic acid and dideoxy dNTPs to “tailor” DNA templates for accurate sequencing to overcome this hurdle. We also devised an accelerated “dyad” pyrosequencing strategy, such that the combined approach can be used as a faster, more accurate alternative to de novo sequencing. Dyad sequencing interrogates two bases at a time by allowing the polymerase to incorporate two nucleotides to DNA template, cutting the analysis time in half. In addition, for the first time, we show the effect of peptide nucleic acid as a blocking probe to stop polymerization, which is essential to analyze the heterozygous samples by sequencing. This approach provides a new platform for rapid and cost-effective DNA length measurement for STRs and resequencing of small DNA fragments. PMID:20408144

  11. 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

  12. Effect of sampling size on the determination of accurate pesticide residue levels in Japanese agricultural commodities.

    PubMed

    Fujita, Masahiro; Yajima, Tomonari; Iijima, Kazuaki; Sato, Kiyoshi

    2012-05-01

    The uncertainty in pesticide residue levels (UPRL) associated with sampling size was estimated using individual acetamiprid and cypermethrin residue data from preharvested apple, broccoli, cabbage, grape, and sweet pepper samples. The relative standard deviation from the mean of each sampling size (n = 2(x), where x = 1-6) of randomly selected samples was defined as the UPRL for each sampling size. The estimated UPRLs, which were calculated on the basis of the regulatory sampling size recommended by the OECD Guidelines on Crop Field Trials (weights from 1 to 5 kg, and commodity unit numbers from 12 to 24), ranged from 2.1% for cypermethrin in sweet peppers to 14.6% for cypermethrin in cabbage samples. The percentages of commodity exceeding the maximum residue limits (MRLs) specified by the Japanese Food Sanitation Law may be predicted from the equation derived from this study, which was based on samples of various size ranges with mean residue levels below the MRL. The estimated UPRLs have confirmed that sufficient sampling weight and numbers are required for analysis and/or re-examination of subsamples to provide accurate values of pesticide residue levels for the enforcement of MRLs. The equation derived from the present study would aid the estimation of more accurate residue levels even from small sampling sizes. PMID:22475588

  13. Experimental determination of ice sublimation energies

    NASA Astrophysics Data System (ADS)

    Luna, R.; Canto, J.; Satorre, M. A.; Domingo, M.

    2011-11-01

    In Astrophysics, the study of ices is important due to the wide range of scenarios in which they are present. Their physical and chemical characteristics play an important role in the study of the interstellar medium (ISM). The assessment of the energy of sublimation allows us to improve our understanding of physical and/or chemical processes that take place where ices are present. The energy of sublimation E_sub is defined as the change of energy between solid and gas phase of certain molecule. This value is important to determinate other thermodynamical parameters such as the reticular energy of ionic compounds, the energy of formation in gas phase from the energy of formation in condensed phase, or to estimate the sublimation rate, which is very important in determining the evolution of surfaces of astrophysical objects.

  14. Magma fragmentation speed: an experimental determination

    NASA Astrophysics Data System (ADS)

    Spieler, O.; Dingwell, D. B.; Alidibirov, M.

    2004-01-01

    The propagation speed of a fragmentation front, combined with the ascent velocity of magma is, in all likelihood, a controlling factor in the dynamics of explosive volcanic eruptions. Direct measurement of the 'fragmentation speed' in natural systems appears to be impossible at present. Fortunately, laboratory experiments can provide information on the propagation speed of the fragmentation front. Here we present the results of fragmentation speed determinations using a so-called 'fragmentation bomb'. These are, to the best of our knowledge, the first in situ fragmentation speed determinations performed on magma. Natural magma samples (Merapi basaltic andesite, Mount St. Helens dacite and Unzen dacite) have been investigated in the temperature range of 20-950°C and at pressures up to 25 MPa. Two techniques have been employed. Firstly, in experiments at 20°C, dynamic pressure transducers were placed above and below the magma samples and the fragmentation speed of the magma sample was derived from an analysis of the decompression curves. Secondly, at elevated temperatures, an alternative technique was introduced and successfully employed. This involved the severing via fragmentation of conducting wires placed within the samples at various heights. Fragmentation speeds are very low, falling in the range of 2-70 m/s and increasing with an increase in the magnitude of the decompression step responsible for the fragmentation. The first high-temperature determination seems consistent with low-temperature results. Implications for explosive volcanism are discussed briefly.

  15. 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.

  16. 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...

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Yogurtcu, Osman N.; Johnson, Margaret E.

    2015-08-01

    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

  19. 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.

  20. Do Ecological Niche Models Accurately Identify Climatic Determinants of Species Ranges?

    PubMed

    Searcy, Christopher A; Shaffer, H Bradley

    2016-04-01

    Defining species' niches is central to understanding their distributions and is thus fundamental to basic ecology and climate change projections. Ecological niche models (ENMs) are a key component of making accurate projections and include descriptions of the niche in terms of both response curves and rankings of variable importance. In this study, we evaluate Maxent's ranking of environmental variables based on their importance in delimiting species' range boundaries by asking whether these same variables also govern annual recruitment based on long-term demographic studies. We found that Maxent-based assessments of variable importance in setting range boundaries in the California tiger salamander (Ambystoma californiense; CTS) correlate very well with how important those variables are in governing ongoing recruitment of CTS at the population level. This strong correlation suggests that Maxent's ranking of variable importance captures biologically realistic assessments of factors governing population persistence. However, this result holds only when Maxent models are built using best-practice procedures and variables are ranked based on permutation importance. Our study highlights the need for building high-quality niche models and provides encouraging evidence that when such models are built, they can reflect important aspects of a species' ecology. PMID:27028071

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

    NASA Astrophysics Data System (ADS)

    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.

  2. DETERMINING ION COMPOSITIONS USING AN ACCURATE MASS, TRIPLE QUADRUPOLE MASS SPECTROMETER

    EPA Science Inventory

    For the past decade, we have used double focusing mass spectrometers to determine
    compositions of ions observed in mass spectra produced from compounds introduced by GC
    based on measured exact masses of the ions and their +1 and +2 isotopic profiles arising from atoms of ...

  3. 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.

  4. Accurate experimental and theoretical comparisons between superconductor-insulator-superconductor mixers showing weak and strong quantum effects

    NASA Technical Reports Server (NTRS)

    Mcgrath, W. R.; Richards, P. L.; Face, D. W.; Prober, D. E.; Lloyd, F. L.

    1988-01-01

    A systematic study of the gain and noise in superconductor-insulator-superconductor mixers employing Ta based, Nb based, and Pb-alloy based tunnel junctions was made. These junctions displayed both weak and strong quantum effects at a signal frequency of 33 GHz. The effects of energy gap sharpness and subgap current were investigated and are quantitatively related to mixer performance. Detailed comparisons are made of the mixing results with the predictions of a three-port model approximation to the Tucker theory. Mixer performance was measured with a novel test apparatus which is accurate enough to allow for the first quantitative tests of theoretical noise predictions. It is found that the three-port model of the Tucker theory underestimates the mixer noise temperature by a factor of about 2 for all of the mixers. In addition, predicted values of available mixer gain are in reasonable agreement with experiment when quantum effects are weak. However, as quantum effects become strong, the predicted available gain diverges to infinity, which is in sharp contrast to the experimental results. Predictions of coupled gain do not always show such divergences.

  5. On the accurate theoretical determination of the static hyperpolarizability of trans-butadiene

    NASA Astrophysics Data System (ADS)

    Maroulis, George

    1999-07-01

    Finite-field many-body perturbation theory and coupled cluster calculations are reported for the static second dipole hyperpolarizability γαβγδ of trans-butadiene. A very large basis set of [9s6p4d1f/6s3p1d] size (336 contracted Gaussian-type functions) should lead to self-consistent field (SCF) values of near-Hartree-Fock quality. We report γxxxx=6.19, γxxxz=-0.44, γxxyy=3.42, γzzxx=2.07, γxyyz=-0.50, γxzzz=1.73, γyyyy=14.72, γyyzz=8.46, γzzzz=24.10 and γ¯=14.58 for 10-3×γαβγδ/e4a04Eh-3 at the experimental geometry (molecule on the xz plane with z as the main axis). γ¯=(14.6±0.4)×103e4a04Eh-3 should be a very reliable estimate of the Hartree-Fock limit of the mean hyperpolarizability. Keeping all other molecular geometry parameters constant, we find that near the Hartree-Fock limit the mean hyperpolarizability varies with the C=C bond length as 10-3×γ¯(RC=C)/e4a04Eh-3=14.93+31.78ΔR+30.88ΔR2-2.96ΔR3 and with the C-C bond length as 10-3×γ¯(RC-C)/e4a04Eh-3=14.93-7.20ΔR+3.04ΔR2, where ΔR/a0 is the displacement from the respective experimental value. The dependence of the components of γαβγδ on the molecular geometry parameters is not uniform. Electron correlation corrections have been calculated at various molecular geometries at the coupled-cluster single, double and perturbatively linked triple excitations level of theory for all independent components of γαβγδ. In absolute terms, electron correlation affects strongly the γzzzz, less strongly the γxxxx, and even less strongly the out-of-plane component γyyyy. The present analysis suggests a conservative estimate of (3.0±0.6)×103e4a04Eh-3 for the electron correlation correction to γ¯ at the experimental molecular geometry. Most of this value is appropriate to γzzzz. A static limit of γ¯=(17.6±1.0)×103e4a04Eh-3 is advanced (neglecting vibrational averaging). Even if a crude theoretical estimate of the dispersion of γ¯ at 1064 nm is added to this value, the

  6. Molecular Simulation of the Free Energy for the Accurate Determination of Phase Transition Properties of Molecular Solids

    NASA Astrophysics Data System (ADS)

    Sellers, Michael; Lisal, Martin; Brennan, John

    2015-06-01

    Investigating the ability of a molecular model to accurately represent a real material is crucial to model development and use. When the model simulates materials in extreme conditions, one such property worth evaluating is the phase transition point. However, phase transitions are often overlooked or approximated because of difficulty or inaccuracy when simulating them. Techniques such as super-heating or super-squeezing a material to induce a phase change suffer from inherent timescale limitations leading to ``over-driving,'' and dual-phase simulations require many long-time runs to seek out what frequently results in an inexact location of phase-coexistence. We present a compilation of methods for the determination of solid-solid and solid-liquid phase transition points through the accurate calculation of the chemical potential. The methods are applied to the Smith-Bharadwaj atomistic potential's representation of cyclotrimethylene trinitramine (RDX) to accurately determine its melting point (Tm) and the alpha to gamma solid phase transition pressure. We also determine Tm for a coarse-grain model of RDX, and compare its value to experiment and atomistic counterpart. All methods are employed via the LAMMPS simulator, resulting in 60-70 simulations that total 30-50 ns. Approved for public release. Distribution is unlimited.

  7. An accurate method for the determination of carboxyhemoglobin in postmortem blood using GC-TCD.

    PubMed

    Lewis, Russell J; Johnson, Robert D; Canfield, Dennis V

    2004-01-01

    During the investigation of aviation accidents, postmortem samples from accident victims are submitted to the FAA's Civil Aerospace Medical Institute for toxicological analysis. In order to determine if an accident victim was exposed to an in-flight/postcrash fire or faulty heating/exhaust system, the analysis of carbon monoxide (CO) is conducted. Although our laboratory predominantly uses a spectrophotometric method for the determination of carboxyhemoglobin (COHb), we consider it essential to confirm with a second technique based on a different analytical principle. Our laboratory encountered difficulties with many of our postmortem samples while employing a commonly used GC method. We believed these problems were due to elevated methemoglobin (MetHb) concentration in our specimens. MetHb does not bind CO; therefore, elevated MetHb levels will result in a loss of CO-binding capacity. Because most commonly employed GC methods determine %COHb from a ratio of unsaturated blood to CO-saturated blood, a loss of CO-binding capacity will result in an erroneously high %COHb value. Our laboratory has developed a new GC method for the determination of %COHb that incorporates sodium dithionite, which will reduce any MetHb present to Hb. Using blood controls ranging from 1% to 67% COHb, we found no statistically significant differences between %COHb results from our new GC method and our spectrophotometric method. To validate the new GC method, postmortem samples were analyzed with our existing spectrophotometric method, a GC method commonly used without reducing agent, and our new GC method with the addition of sodium dithionite. As expected, we saw errors up to and exceeding 50% when comparing the unreduced GC results with our spectrophotometric method. With our new GC procedure, the error was virtually eliminated. PMID:14987426

  8. Determination of the biotin content of select foods using accurate and sensitive HPLC/avidin binding

    PubMed Central

    Staggs, C.G.; Sealey, W.M.; McCabe, B.J.; Teague, A.M.; Mock, D.M.

    2006-01-01

    Assessing dietary biotin content, biotin bioavailability, and resulting biotin status are crucial in determining whether biotin deficiency is teratogenic in humans. Accuracy in estimating dietary biotin is limited both by data gaps in food composition tables and by inaccuracies in published data. The present study applied sensitive and specific analytical techniques to determine values for biotin content in a select group of foods. Total biotin content of 87 foods was determined using acid hydrolysis and the HPLC/avidin-binding assay. These values are consistent with published values in that meat, fish, poultry, egg, dairy, and some vegetables are relatively rich sources of biotin. However, these biotin values disagreed substantially with published values for many foods. Assay values varied between 247 times greater than published values for a given food to as much as 36% less than the published biotin value. Among 51 foods assayed for which published values were available, only seven agreed within analytical variability (720%). We conclude that published values for biotin content of foods are likely to be inaccurate. PMID:16648879

  9. 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

  10. 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.

  11. Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer

    SciTech Connect

    Stolzenberg, H.; Becker, S.; Bollen, G.; Kern, F.; Kluge, H.; Otto, T.; Savard, G.; Schweikhard, L. ); Audi, G. ); Moore, R.B. ); The ISOLDE Collaboration

    1990-12-17

    A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for {sup 118}Cs--{sup 137}Cs. A resolving power of over 10{sup 6} and an accuracy of 1.4{times}10{sup {minus}7} have been achieved, corresponding to about 20 keV.

  12. 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.

  13. 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.

  14. Determining the minimum sampling rate needed to accurately quantify cumulative spine loading from digitized video.

    PubMed

    Andrews, D M; Callaghan, J P

    2003-11-01

    Cumulative low back loads have been linked to the reporting of low back pain. Traditional video-based methods used to estimate these loads are time intensive for data collection and analysis. Sampling less frequently would help to reduce the associated time and cost of this type of approach. The purpose of this study was to determine how the error in estimated cumulative low back loads is affected by reducing video sampling rate. Ten healthy male university students performed three laboratory, sagittal plane lifts of varying mass (2.3, 8.8, and 15.9 kg), speed (0.2, 0.4, 0.8 m/s), and postural demand (lift from floor to table; lower from shelf to table; lift from floor over barrier and lower to floor) while being videotaped (60 frames/s). Digitized body coordinates and anthropometrics were input into a static biomechanical model, resulting in estimates of low back compression and shear forces, and moment. Load-time histories for each condition underwent rectangular integration at 60 (gold standard), 30, 20, 15, 12, 10, 6, 5, 4, 3, 2 and 1 frames/s, resulting in estimates of low back cumulative loads. Mean relative errors with respect to 60 frames/s for all cumulative loads and all conditions were found to be below 8% at 1 frame/s, and less than 3% at 2 frames/s. In addition, analyses at sampling rates above 3 frames/s were not significantly different than the cumulative loads determined at 60 frames/s, for all conditions. The accuracy of cumulative loads exhibited even at low sampling rates can be attributed, in part, to the fact that overestimations and underestimations of the integrated loads tend to cancel out over the length of the tasks considered. PMID:14559419

  15. Accurate determination of the interaction between Λ hyperons and nucleons from auxiliary field diffusion Monte Carlo calculations

    NASA Astrophysics Data System (ADS)

    Lonardoni, D.; Pederiva, F.; Gandolfi, S.

    2014-01-01

    Background: An accurate assessment of the hyperon-nucleon interaction is of great interest in view of recent observations of very massive neutron stars. The challenge is to build a realistic interaction that can be used over a wide range of masses and in infinite matter starting from the available experimental data on the binding energy of light hypernuclei. To this end, accurate calculations of the hyperon binding energy in a hypernucleus are necessary. Purpose: We present a quantum Monte Carlo study of Λ and ΛΛ hypernuclei up to A =91. We investigate the contribution of two- and three-body Λ-nucleon forces to the Λ binding energy. Method: Ground state energies are computed solving the Schrödinger equation for nonrelativistic baryons by means of the auxiliary field diffusion Monte Carlo algorithm extended to the hypernuclear sector. Results: We show that a simple adjustment of the parameters of the ΛNN three-body force yields a very good agreement with available experimental data over a wide range of hypernuclear masses. In some cases no experiments have been performed yet, and we give new predictions. Conclusions: The newly fitted ΛNN force properly describes the physics of medium-heavy Λ hypernuclei, correctly reproducing the saturation property of the hyperon separation energy.

  16. Experimental determination of the effective Taylor dispersivity in a fracture

    SciTech Connect

    Gilardi, J.R.

    1984-06-01

    The applicability and accuracy of the approximation for Taylor Dispersion was experimentally determined for the diffusion of a chemical tracer in flow through a fracture. 12 refs., 16 figs., 10 tabs. (ACR)

  17. Accurate Determination of Rotational Energy Levels in the Ground State of ^{12}CH_4

    NASA Astrophysics Data System (ADS)

    Abe, M.; Iwakuni, K.; Okubo, S.; Sasada, H.

    2013-06-01

    We have measured absolute frequencies of saturated absorption of 183 allowed and 21 forbidden transitions in the νb{3} band of ^{12}CH_4 using an optical comb-referenced difference-frequency-generation spectrometer from 86.8 to 93.1 THz (from 2890 to 3100 wn). The pump and signal sources are a 1.06-μ m Nd:YAG laser and a 1.5-μ m extended-cavity laser diode. An enhanced-cavity absorption cell increases the optical electric field and enhances the sensitivity. The typical uncertainty is 3 kHz for the allowed transitions and 12 kHz for the forbidden transitions. Twenty combination differences are precisely determined, and the scalar rotational and centrifugal distortion constants of the ground state are thereby yielded as r@ = l@ r@ = l B_{{s}} (157 122 614.2 ± 1.5) kHz, D_{{s}} (3 328.545 ± 0.031) kHz, H_{{s}} (190.90 ± 0.26) Hz, and L_{{s}} (-13.16 ± 0.76) mHz. Here, B_{{s}} is the rotational constant and D_{{s}}, H_{{s}} and L_{{s}} are the scalar quartic, sextic, octic distortion constants. The relative uncertainties are considerably smaller than those obtained from global analysis of Fourier-transform infrared spectroscopy. S. Okubo, H. Nakayama, K. Iwakuni, H. Inaba and H. Sasada, Opt. Express 19, 23878 (2011). M. Abe, K. Iwakuni, S. Okubo, and H. Sasada, J. Opt. Soc. Am. B (to be published). S. Albert, S. Bauerecker, V. Boudon, L. R. Brown, J. -P. Champion, M. Loëte, A. Nikitin, and M. Quack, Chem. Phys. 356, 131 (2009).

  18. Determining point charge arrays that produce accurate ionic crystal fields for atomic cluster calculations

    SciTech Connect

    Derenzo, Stephen E.; Klintenberg, Mattias K.; Weber, Marvin J.

    2000-02-01

    In performing atomic cluster calculations of local electronic structure defects in ionic crystals, the crystal is often modeled as a central cluster of 5-50 ions embedded in an array of point charges. For most crystals, however, a finite three-dimensional repeated array of unit cells generates electrostatic potentials that are in significant disagreement with the Madelung (infinite crystal) potentials computed by the Ewald method. This is illustrated for the cubic crystal CaF{sub 2}. We present a novel algorithm for solving this problem for any crystal whose unit cell information is known: (1) the unit cell is used to generate a neutral array containing typically 10 000 point charges at their normal crystallographic positions; (2) the array is divided into zone 1 (a volume defined by the atomic cluster of interest), zone 2 (several hundred additional point charges that together with zone 1 fill a spherical volume), and zone 3 (all other point charges); (3) the Ewald formula is used to compute the site potentials at all point charges in zones 1 and 2; (4) a system of simultaneous linear equations is solved to find the zone 3 charge values that make the zone 1 and zone 2 site potentials exactly equal to their Ewald values and the total charge and dipole moments equal to zero, and (5) the solution is checked at 1000 additional points randomly chosen in zone 1. The method is applied to 33 different crystal types with 50-71 ions in zone 1. In all cases the accuracy determined in step 5 steadily improves as the sizes of zones 2 and 3 are increased, reaching a typical rms error of 1 {mu}V in zone 1 for 500 point charges in zone 2 and 10 000 in zone 3. (c) 2000 American Institute of Physics.

  19. Blast-induced biomechanical loading of the rat: an experimental and anatomically accurate computational blast injury model.

    PubMed

    Sundaramurthy, Aravind; Alai, Aaron; Ganpule, Shailesh; Holmberg, Aaron; Plougonven, Erwan; Chandra, Namas

    2012-09-01

    Blast waves generated by improvised explosive devices (IEDs) cause traumatic brain injury (TBI) in soldiers and civilians. In vivo animal models that use shock tubes are extensively used in laboratories to simulate field conditions, to identify mechanisms of injury, and to develop injury thresholds. In this article, we place rats in different locations along the length of the shock tube (i.e., inside, outside, and near the exit), to examine the role of animal placement location (APL) in the biomechanical load experienced by the animal. We found that the biomechanical load on the brain and internal organs in the thoracic cavity (lungs and heart) varied significantly depending on the APL. When the specimen is positioned outside, organs in the thoracic cavity experience a higher pressure for a longer duration, in contrast to APL inside the shock tube. This in turn will possibly alter the injury type, severity, and lethality. We found that the optimal APL is where the Friedlander waveform is first formed inside the shock tube. Once the optimal APL was determined, the effect of the incident blast intensity on the surface and intracranial pressure was measured and analyzed. Noticeably, surface and intracranial pressure increases linearly with the incident peak overpressures, though surface pressures are significantly higher than the other two. Further, we developed and validated an anatomically accurate finite element model of the rat head. With this model, we determined that the main pathway of pressure transmission to the brain was through the skull and not through the snout; however, the snout plays a secondary role in diffracting the incoming blast wave towards the skull. PMID:22620716

  20. Experimental Techniques Verified for Determining Yield and Flow Surfaces

    NASA Technical Reports Server (NTRS)

    Lerch, Brad A.; Ellis, Rod; Lissenden, Cliff J.

    1998-01-01

    Structural components in aircraft engines are subjected to multiaxial loads when in service. For such components, life prediction methodologies are dependent on the accuracy of the constitutive models that determine the elastic and inelastic portions of a loading cycle. A threshold surface (such as a yield surface) is customarily used to differentiate between reversible and irreversible flow. For elastoplastic materials, a yield surface can be used to delimit the elastic region in a given stress space. The concept of a yield surface is central to the mathematical formulation of a classical plasticity theory, but at elevated temperatures, material response can be highly time dependent. Thus, viscoplastic theories have been developed to account for this time dependency. Since the key to many of these theories is experimental validation, the objective of this work (refs. 1 and 2) at the NASA Lewis Research Center was to verify that current laboratory techniques and equipment are sufficient to determine flow surfaces at elevated temperatures. By probing many times in the axial-torsional stress space, we could define the yield and flow surfaces. A small offset definition of yield (10 me) was used to delineate the boundary between reversible and irreversible behavior so that the material state remained essentially unchanged and multiple probes could be done on the same specimen. The strain was measured with an off-the-shelf multiaxial extensometer that could measure the axial and torsional strains over a wide range of temperatures. The accuracy and resolution of this extensometer was verified by comparing its data with strain gauge data at room temperature. The extensometer was found to have sufficient resolution for these experiments. In addition, the amount of crosstalk (i.e., the accumulation of apparent strain in one direction when strain in the other direction is applied) was found to be negligible. Tubular specimens were induction heated to determine the flow

  1. Accurate determination of the temperature dependent thermalization coefficient (Q) in InAs/AlAsSb quantum wells

    NASA Astrophysics Data System (ADS)

    Esmaielpour, Hamidreza; Tang, Jinfeng; Whiteside, Vincent R.; Vijeyaragunathan, Sangeetha; Mishima, Tetsuya D.; Santos, Michael B.; Sellers, Ian R.

    2015-03-01

    We present an investigation of hot carriers in InAs/AlAsSb quantum wells as a practical candidate for a hot carrier solar cell absorber. The thermalization coefficient (Q) of the sample is investigated using continuous wave photoluminescence (PL). The Q is accurately determined through transfer matrix calculations of the absorption, analysis of the power density, penetration depth, diffusion, and recombination rates using a combination of simulation and empirical methods. A precise measurement of laser spot size is important in order to determine the absorbed power density. Simulations were performed based on our PL geometry in order to calculate the excitation spot size, which was compared with experiment by measurements using variable diameter pinholes to determine beam radius. Here, these techniques are described, in addition to, the temperature dependent hot carrier dynamics and phonon mediated thermalization coefficient for the InAs/AlAsSb quantum well structure.

  2. Multiclass semi-volatile compounds determination in wine by gas chromatography accurate time-of-flight mass spectrometry.

    PubMed

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Silva, A; Cela, R

    2016-04-15

    The performance of gas chromatography (GC) with accurate, high resolution mass spectrometry (HRMS) for the determination of a group of 39 semi-volatile compounds related to wine quality (pesticide residues, phenolic off-flavours, phenolic pollutants and bioactive stilbenes) is investigated. Solid-phase extraction (SPE) was used as extraction technique, previously to acetylation (phenolic compounds) and dispersive liquid-liquid microextraction (DLLME) concentration. Compounds were determined by GC coupled to a quadrupole time-of-flight (QTOF) MS system through an electron ionization (EI) source. The final method attained limits of quantification (LOQs) at the very low ng mL(-1) level, covering the range of expected concentrations for target compounds in red and white wines. For 38 out of 39 compounds, performance of sample preparation and determination steps were hardly affected by the wine matrix; thus, accurate recoveries were achieved by using pseudo-external calibration. Levels of target compounds in a set of 25 wine samples are reported. The capabilities of the described approach for the post-run identification of species not considered during method development, without retention time information, are illustrated and discussed with selected examples of compounds from different classes. PMID:26971021

  3. 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. PMID:27409119

  4. An accurate and simple technique of determination of the maximum power point and measurement of some solar cell parameters

    NASA Astrophysics Data System (ADS)

    Deb, S.; Maitra, K.; Roychoudhuri, A.

    1985-06-01

    In the wake of the energy crisis, attempts are being made to develop a variety of energy conversion devices, such as solar cells. The single most important operational characteristic for a conversion element generating electricity is the V against I curve. Three points on this characteristic curve are of paramount importance, including the short-circuit, the open-circuit, and the maximum power point. The present paper has the objective to propose a new simple and accurate method of determining the maximum power point (Vm, Im) of the V against I characteristics, based on a geometrical interpretation. The method is general enough to be applicable to any energy conversion device having a nonlinear V against I characteristic. The paper provides also a method for determining the fill factor (FF), the series resistance (Rs), and the diode ideality factor (A) from a single set of connected observations.

  5. 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.

  6. Rapid and accurate determination of total lung capacity (TLC) from routine chest radiograms using a programmable hand-held calculator.

    PubMed

    Rodgers, R P; Tannen, R

    1983-01-01

    Since its appearance in 1960, the method of Barnhard and associates for the determination of total lung capacity (TLC) from routine chest radiograms has been widely studied in normal and diseased subjects. The method appears to be as accurate as the current definitive procedure, total body plethysmography. The method is in routine use in major medical institutions where the procedure has been automated, but the method does not seem to have gained the wide use it deserves. This is likely due to the tedium of the technique when performed manually--a single determination can require 30 min. We present here an implementation of the Barnhard method for the HP41-C hand-held programmable calculator. In conjunction with the use of a transparent reticle used for obtaining the required measurements, the program allows a single measurement to be made in under 12 minutes. We hope this technique will make radiographic TLC measurements more broadly accessible to the medical profession. PMID:6872526

  7. 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.

  8. 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.

    2016-02-01

    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.

  9. Experimental Determination of Structure Factors of Titanium Aluminum and Silicon

    NASA Astrophysics Data System (ADS)

    Subramanian, Swaminathan

    Brittleness of TiAl has been attributed to strong directional bonding by a number of researchers. Their predictions have been based on theoretical calculations of electron charge density distribution. It is necessary to complement these predictions by experimental measurements. The work described in this thesis, aimed towards that end, involves measurement of Debye-Waller factors by four circle x-ray diffraction and of structure factors by energy filtered convergent beam electron diffraction CBED methods. Stoichiometric single crystals are required for the measurement of Debye-Waller factors by the four circle x-ray diffraction method. Because of constraints imposed by the phase diagram only non-stoichiometric single crystal of TiAl are available. Measurement of Debye-Waller parameters have been attempted by using aluminum rich TiAl single crystals of compositions Ti54at%Al and Ti56at%Al. The symmetry of L1_0 structure of TiAl dictates that all reflections with Miller indices (hkl) not satisfying the condition h + k = 2n should be extinct. However, during the x-ray diffraction experiments diffuse diffracted intensities were observed for reflections of h + k = 2n + 1 type. This indicates the possibility of occupation of the excess Al atoms on the Ti-sites. If the excess Al atom preferentially occupies one of the Ti-sites, it would lead to the formation of L1_2 type TiAl_3 unit cells within the TiAl lattice. This notion has been further verified by least-squares refinement of the data obtained from Ti54at%Al single crystal. Also Debye-Waller factor values were different for equivalent Ti-sites in TiAl. The CBED method was developed for accurate structure factor measurement. Factors such as limitation due to the angular resolution of the aperture and complex matrix and perturbation treatment of absorption have been considered. Computer routines, incorporating these factors, have been developed for the calculation of CBED patterns and for matching the rocking curves

  10. Determining the performance of energy wheels: Part 2 -- Experimental data and numerical validation

    SciTech Connect

    Simonson, C.J.; Ciepliski, D.L.; Besant, R.W.

    1999-07-01

    Experimentally measured and numerically simulated performance data are presented for an energy wheel operating in a wide range of conditions for mass flux, temperature, and humidity. Typically, the agreement between simulated and measured results is well within the experimental uncertainty. Both the simulated and numerical results show that the three effectiveness values (i.e., sensible, latent, and total) are unequal and each has its own unique sensitivity to operating conditions. Also, total effectiveness is shown to be a poor measurement of performance when the supply and exhaust inlet air enthalpies are nearly equal. Simulated results with the numerical model show that experimental results measured using half of the energy wheel, to reduce equipment sizes, underpredict the measured sensible effectiveness by up to 7%. The proposed method of determining energy wheel performance is to validate a detailed numerical model with a range of accurate experimental data and then use the model to predict performance for other operating conditions.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  13. 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. PMID:24845315

  14. 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.

  15. Direct experimental determination of Frisch grid inefficiency in ionization chamber

    NASA Astrophysics Data System (ADS)

    Khriachkov, V. A.; Goverdovski, A. A.; Ketlerov, V. V.; Mitrofanov, V. F.; Semenova, N. N.

    1997-07-01

    The present work describes the method of direct experimental determination of the Frisch grid inefficiency in an ionization chamber. The method is based on analysis of the anode signal after Waveform Digitizer. It is shown that the calculated grid inefficiency value can differ much from the measured ones.

  16. 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.

  17. Statistical Evaluation of Experimental Determinations of Neutrino Mass Hierarchy

    SciTech Connect

    X. Qian, A. Tan, W. Wang, J. J. Ling, R. D. McKeown, C. Zhang

    2012-12-01

    Statistical methods of presenting experimental results in constraining the neutrino mass hierarchy (MH) are discussed. Two problems are considered and are related to each other: how to report the findings for observed experimental data, and how to evaluate the ability of a future experiment to determine the neutrino mass hierarchy, namely, sensitivity of the experiment. For the first problem where experimental data have already been observed, the classical statistical analysis involves constructing confidence intervals for the parameter {Delta}m{sup 2}{sub 32}. These intervals are deduced from the parent distribution of the estimation of {Delta}m{sup 2}{sub 32} based on experimental data. Due to existing experimental constraints on |{Delta}m{sup 2}{sub 32}|, the estimation of {Delta}m{sup 2}{sub 32} is better approximated by a Bernoulli distribution (a Binomial distribution with 1 trial) rather than a Gaussian distribution. Therefore, the Feldman-Cousins approach needs to be used instead of the Gaussian approximation in constructing confidence intervals. Furthermore, as a result of the definition of confidence intervals, even if it is correctly constructed, its confidence level does not directly reflect how much one hypothesis of the MH is supported by the data rather than the other hypothesis. We thus describe a Bayesian approach that quantifies the evidence provided by the observed experimental data through the (posterior) probability that either one hypothesis of MH is true. This Bayesian presentation of observed experimental results is then used to develop several metrics to assess the sensitivity of future experiments. Illustrations are made using a simple example with a confined parameter space, which approximates the MH determination problem with experimental constraints on the |{Delta}m{sup 2}{sub 32}|.

  18. 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

  19. Limitation of secondary electron multiplier non-linearity on accurate U-Th isotopic determination by MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Shen, C.; Wu, C.; Gallet, S.; Cheng, H.; Edwards, R.; Hsieh, Y.; Lin, K.

    2008-12-01

    Contemporary multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS) with discrete dynode secondary electron multipliers (SEMs) can offer U-Th isotopic determinations with subpermil-permil- level precision in femtogram quantities. However, accurate isotopic measurement requires fully understanding SEM mass and intensity biases. In additional to dead-time effect, Richter et al (2001, Int. J. Mass Spectrom., 206, 105-127) reported a nonlinearity on SEMs produced by ETP and MasCom for count rates > 20 thousand counts per second (cps). We evaluated the possible biases for ion beams of 500- 1,600,000 cps on a latest MasCom SEM, SEV TE-Z/17, with more effective ion optical acceptance area (>50%) and better peak shape than previous models, used in a MC-ICP-MS, Thermo Fisher NEPTUNE. With the retarding potential quadruple lens (RPQ) turned off, ion beam intensity can be biased by only dead- time effect, which can be precisely corrected online or offline. With the RPQ on, two additional biases, an exponential-like increase of ion beam intensity from 100-100,000 s cps and an apparent dead-time effect (-2 to 2 ns) at high count rates, are observed. They are likely caused by the slightly defocused ions with a wide kinetic energy spread of ~5 eV, 10 times worse than that with thermal source, passing through the RPQ lens to the SEM, which is installed behind the focal plane. Fortunately, the two biases, which are stable during the daily measurements with the same settings of inlet system, source lenses, zoom optics, and RPQ, can be corrected effectively offline to earn accurate U-Th isotopic measurement.

  20. Direct experimental determination of voltage across high-low junctions

    NASA Technical Reports Server (NTRS)

    Daud, T.; Lindholm, F. A.

    1986-01-01

    High-low (HL) junctions form a part of many semiconductor devices, including back surface field solar cells. A first experimental determination and interpretation of the voltage across the HL junction under low- and high-injection conditions is presented as a function of the voltage across a nearby p/n junction. Theoretical analysis from first principles is shown to bear well on the experimental results. In addition, a test structure is proposed for measurement of the effective surface recombination velocity at the HL junctions.

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

    NASA Astrophysics Data System (ADS)

    Liritzis, I.; et al.

    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.

  2. Experimentally Determined Binding Energies of Astrophysically Relevant Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Behmard, Aida; Graninger, Dawn; Oberg, Karin I.

    2016-06-01

    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 the desorption temperatures and binding energies of 1, 2, and 3-carbon interstellar hydrocarbons (CH4, H3CCH3, H2CCH2, C3H8, HCCCH3, and C3H6). 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.

  3. 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. PMID:22340891

  4. Experimental determination of Cm measurement related hardware parameters of the patch-clamp amplifier.

    PubMed

    Zhang, Hao; Xiong, Jun; Luo, Jie; Qu, Anlian

    2009-01-30

    Accurate Cm measurements rely on accurate determination of specific parameters of a patch-clamp amplifier (PCA). Hardware-related parameters, such as the resistance Rf and the stray capacitance Cf of the feedback resistor, the input capacitance Ci, the injection capacitance Cj, and the extra capacitances introduced by the BNC connector, are of significance in the sense of obtaining absolute estimates of cell parameters. In the present paper, a frequency-domain method, or the f-method for simplicity, is put forward to experimentally determine the actual values of basic circuit elements for our self-developed PCA. The f-method makes use of sine waves and amplitude/phase measurements instead of the square-wave responses to determine the above parameters of a PCA, and thereby calibrates the PAC for capacitance measurements. Experimental results prove that the f-method is excellent in determining hardware-related parameters, with 3-5% error of the impedance of the "10 MOmega setting", and about 2% error of the impedance of the "model cell" of the model circuit for our PCA. The f-method enables us not only to picture components of fast capacitances, but also to guarantee complete fast capacitance compensation; it may be applicable for other PCAs. PMID:18789969

  5. 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.

  6. Method of fission heat flux determination from experimental data

    SciTech Connect

    Paxton, F.A.

    1999-09-28

    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.

  7. 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.

  8. A unique method of neutron flux determination from experimental data

    SciTech Connect

    Paxton, Frank A.

    1998-12-01

    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.

  9. 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].

  10. 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. PMID:24354624

  11. Delay Discounting of Self-Determined and Experimenter-Determined Commodities

    ERIC Educational Resources Information Center

    Weatherly, Jeffrey N.; Gudding, Jennifer; Derenne, Adam

    2010-01-01

    Research suggests that individuals prefer self-determined reinforcers over experimenter-determined ones. The present study had 518 college students complete a delay-discounting task in which the commodity was cigarettes, a grocery store gift card, casino tokens, cash, or the choice of the four. The least amount of delay discounting was observed…

  12. Accurate Focal Depth Determination of Oceanic Earthquakes Using Water-column Reverberation and Some Implications for the Shrinking Plate Hypothesis

    NASA Astrophysics Data System (ADS)

    Niu, F.; Huang, J.; Gordon, R. G.

    2015-12-01

    Investigation of oceanic earthquakes can play an important role in constraining the lateral and depth variations of the stress and strain-rate fields in oceanic lithosphere and of 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 occur in ≈25 Ma-old lithosphere and were previously estimated to have very 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 compression to horizontal extension as depth increases, which is consistent with the prediction of the lithospheric cooling model. Furthermore, we show that the P-axis of the newly investigated thrust-faulting earthquake is roughly perpendicular to that of the previously studied thrust event, consistent with the predictions of the shrinking-plate hypothesis.

  13. 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.

  14. 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.

  15. Accurate determination of the successive moments of the sun: a new window open on the sun's interior

    NASA Astrophysics Data System (ADS)

    Rozelot, J. P.; Godier, S.

    Despite its great importance for solar physics, mainly in the fields of solar fundamental astrometry, helioseismology, planetary motions and relativistic effects, the successive zonal harmonics of the Sun still remain elusive and subject to some controversy. Direct observations from the ground suffer from atmospheric effects and are not of enough accuracy. Up to now, space flights (SOHO) or balloon missions give consistent data but lead to spurious results due to the noise. As far as indirect observations are concerned, the more precise determination of the successive moments (mainly J 2, J 4 and even J 6), will be provided unambiguously by the study of the orbit of a spacecraft flying close to the Sun or around Mercury. This has been scheduled, but not yet achieved. In this paper we will first emphasize why it is important to know the successive zonal harmonics of the Sun with a high accuracy. We will show how their precise knowledge permits to obtain informations on the Sun's interior, mainly the shear's regions (tacholine or leptocline). Then we will give an up-to-date review of both theories (including the heliosismology approach) and data. We will explain some of the difficulties, mainly due to the differential rotation and we will give an insight of what the PICARD's mission will bring in that field. Then we will propose a novel concept for a Sun's mission, which would lead to the most accurate determination of the successive solar moments (that could be part of another project), and thus opening a new window on the Sun's interior.

  16. 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. PMID:26631397

  17. 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…

  18. 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.

  19. 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

  20. 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.

  1. THEORETICAL CHALLENGE TO THE EXPERIMENTALLY DETERMINED GEOMETRICAL STRUCTURE OF DIMETHYLSILAETHYLENE

    SciTech Connect

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

    1980-09-01

    The equilibrium geometries of (CH{sub 3}){sub 2}Si=CH{sub 2} and H{sub 2}Si=CH{sub 2} 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. On this basis 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 {Angstrom}, while the range of experimental values presented was 1.815 - 1.835 {Angstrom}.

  2. 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. PMID:24859245

  3. Direct experimental determination of spectral densities of molecular complexes

    NASA Astrophysics Data System (ADS)

    Pachón, Leonardo A.; Brumer, Paul

    2014-11-01

    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.

  4. Determination of Baylisascaris schroederi infection in wild giant pandas by an accurate and sensitive PCR/CE-SSCP method.

    PubMed

    Zhang, Wenping; Yie, Shangmian; Yue, Bisong; Zhou, Jielong; An, Renxiong; Yang, Jiangdong; Chen, Wangli; Wang, Chengdong; Zhang, Liang; Shen, Fujun; Yang, Guangyou; Hou, Rong; Zhang, Zhihe

    2012-01-01

    It has been recognized that other than habitat loss, degradation and fragmentation, the infection of the roundworm Baylisascaris schroederi (B. schroederi) is one of the major causes of death in wild giant pandas. However, the prevalence and intensity of the parasite infection has been inconsistently reported through a method that uses sedimentation-floatation followed by a microscope examination. This method fails to accurately determine infection because there are many bamboo residues and/or few B. schroederi eggs in the examined fecal samples. In the present study, we adopted a method that uses PCR and capillary electrophoresis combined with a single-strand conformation polymorphism analysis (PCR/CE-SSCP) to detect B. schroederi infection in wild giant pandas at a nature reserve, and compared it to the traditional microscope approach. The PCR specifically amplified a single band of 279-bp from both fecal samples and positive controls, which was confirmed by sequence analysis to correspond to the mitochondrial COII gene of B. schroederi. Moreover, it was demonstrated that the amount of genomic DNA was linearly correlated with the peak area of the CE-SSCP analysis. Thus, our adopted method can reliably detect the infectious prevalence and intensity of B. schroederi in wild giant pandas. The prevalence of B. schroederi was found to be 54% in the 91 fecal samples examined, and 48% in the fecal samples of 31 identified individual giant pandas. Infectious intensities of the 91 fecal samples were detected to range from 2.8 to 959.2 units/gram, and from 4.8 to 959.2 units/gram in the fecal samples of the 31 identified giant pandas. For comparison, by using the traditional microscope method, the prevalence of B. schroederi was found to be only 33% in the 91 fecal samples, 32% in the fecal samples of the 31 identified giant pandas, and no reliable infectious intensity was observed. PMID:22911871

  5. 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).

  6. Experimental Investigation of the Momentum Method for Determining Profile Drag

    NASA Technical Reports Server (NTRS)

    Goett, Harry J

    1939-01-01

    Report presents the results of an experimental investigation conducted in the full-scale tunnel to determine the accuracy of the Jones and the Betz equations for computing profile drag from total and static pressure surveys in the wake of wings. Surveys were made behind 6 by 8-foot airfoils of the NACA 0009, and 0018 sections at zero lift and behind the NACA 0012 at positive lifts. The surveys were made at various spanwise positions and at distances behind the airfoil ranging from 0.05c to 3.00c.

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

    PubMed

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

    2000-01-01

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

  8. Experimental determinations of Mueller scattering matrices for nonspherical particles.

    PubMed

    Perry, R J; Hunt, A J; Huffman, D R

    1978-09-01

    Measurements have been made to determine all sixteen elements of the Mueller scattering matrix for two types of nonspherical particles. Rounded particles of ammonium sulfate and nearly cubic particles of sodium chloride in the 0.1-1.0-mum size range have been prepared by nebulizing salt water solutions and drying the droplets. Scanning electron micrographs are used to determine size distributions used in Mie calculations of all matrix elements. The expected symmetry of the scattering matrices across the diagonal was confirmed, and the expected eight of the sixteen elements were found to be zero within measurement accuracy. The rounded particles were found accurately to obey Mie theory, while the cubic particles were poorly described by Mie theory for some matrix elements and some angles. Total intensity and linear polarization measurements are presented also for a series of increasing sizes of rounded and cubic particles. A discussion of the effect of nonsphericity on the various matrix elements is given, and applications of these results are given to analysis of particle properties in the laboratory, the clouds of Venus, reflection nebulae, the zodiacal light, and atmospheric particulates. PMID:20203854

  9. 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.

  10. 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. PMID:23856232

  11. Nondestructive experimental determination of bimaterial rectangular cantilever spring constants in water

    SciTech Connect

    Snow, David E.; Kim, Dae Jung; Hope-Weeks, Louisa J.; Weeks, Brandon L.; Pitchimani, Rajasekar

    2008-08-15

    In order to address the issue of spring constant calibration in viscous fluids such as water, a new method is presented that allows for the experimental calibration of bimaterial cantilever spring constants. This method is based on modeling rectangular cantilever beam bending as a function of changing temperature. The temperature change is accomplished by heating water as it flows around the cantilever beams in an enclosed compartment. The optical static method of detection is used to measure the deflection of cantilever at the free end. Experimentally determined results are compared to Sader's method and to the Thermotune method most commonly used in cantilever calibrations. Results indicate that the new bimaterial thermal expansion method is accurate within 15%-20% of the actual cantilever spring constant, which is comparable to other nondestructive calibration techniques.

  12. Nondestructive experimental determination of bimaterial rectangular cantilever spring constants in water.

    PubMed

    Snow, David E; Weeks, Brandon L; Kim, Dae Jung; Pitchimani, Rajasekar; Hope-Weeks, Louisa J

    2008-08-01

    In order to address the issue of spring constant calibration in viscous fluids such as water, a new method is presented that allows for the experimental calibration of bimaterial cantilever spring constants. This method is based on modeling rectangular cantilever beam bending as a function of changing temperature. The temperature change is accomplished by heating water as it flows around the cantilever beams in an enclosed compartment. The optical static method of detection is used to measure the deflection of cantilever at the free end. Experimentally determined results are compared to Sader's method and to the Thermotune method most commonly used in cantilever calibrations. Results indicate that the new bimaterial thermal expansion method is accurate within 15%-20% of the actual cantilever spring constant, which is comparable to other nondestructive calibration techniques. PMID:19044356

  13. Experimental determination of the dynamics of vacuum impregnation of apples.

    PubMed

    Laurindo, J B; Stringari, G B; Paes, S S; Carciofi, B A M

    2007-10-01

    Vacuum impregnation (VI) is a food processing method by which air and native solution are removed from porous spaces within a food and replaced by an external solution. In this study, an experimental device based on a previous design was built, including some modifications, in order to investigate the dynamics of the VI process. The device measured the net force exerted by a food sample submitted to the VI process using a load cell. The influence of the vacuum level and sample geometry was well quantified by the experimental procedure and the modified equipment using apple samples (Fuji var.) as a food model. The results indicated that the experimental device proposed in this study, together with the suggested procedure, is a useful tool to investigate the dynamics of VI processes. It is robust and versatile, and has the advantage of not requiring the determination of the water evaporated during the VI process in a separate experiment, which represents an increase in the accuracy of the results. PMID:17995607

  14. Direct experimental determination of the atomic structure at internal interfaces

    SciTech Connect

    Browning, N.D. |; Pennycook, S.J.

    1995-07-01

    A crucial first step in understanding the effect that internal interfaces have on the properties of materials is the ability to determine the atomic structure at the interface. As interfaces can contain atomic disorder, dislocations, segregated impurities and interphases, sensitivity to all of these features is essential for complete experimental characterization. By combining Z-contrast imaging and electron energy loss spectroscopy (EELS) in a dedicated scanning transmission electron microscope (STEM), the ability to probe the structure, bonding and composition at interfaces with the necessary atomic resolution has been obtained. Experimental conditions can be controlled to provide, simultaneously, both incoherent imaging and spectroscopy. This enables interface structures observed in the image to be interpreted intuitively and the bonding in a specified atomic column to be probed directly by EELS. The bonding and structure information can then be correlated using bond-valence sum analysis to produce structural models. This technique is demonstrated for 25{degrees}, 36{degrees} and 67{degrees} symmetric and 45{degrees} and 25{degrees} asymmetric [001] tilt grain boundaries in SrTiO{sub 3} The structures of both types of boundary were found to contain partially occupied columns in the boundary plane. From these experimental results, a series of structural units were identified which could be combined, using continuity of gain boundary structure principles, to construct all [001] tilt boundaries in SrTiO{sub 3}. Using these models, the ability of this technique to address the issues of vacancies and dopant segregation at grain boundaries in electroceramics is discussed.

  15. Quantitative Determination of Isotope Ratios from Experimental Isotopic Distributions

    PubMed Central

    Kaur, Parminder; O’Connor, Peter B.

    2008-01-01

    Isotope variability due to natural processes provides important information for studying a variety of complex natural phenomena from the origins of a particular sample to the traces of biochemical reaction mechanisms. These measurements require high-precision determination of isotope ratios of a particular element involved. Isotope Ratio Mass Spectrometers (IRMS) are widely employed tools for such a high-precision analysis, which have some limitations. This work aims at overcoming the limitations inherent to IRMS by estimating the elemental isotopic abundance from the experimental isotopic distribution. In particular, a computational method has been derived which allows the calculation of 13C/12C ratios from the whole isotopic distributions, given certain caveats, and these calculations are applied to several cases to demonstrate their utility. The limitations of the method in terms of the required number of ions and S/N ratio are discussed. For high-precision estimates of the isotope ratios, this method requires very precise measurement of the experimental isotopic distribution abundances, free from any artifacts introduced by noise, sample heterogeneity, or other experimental sources. PMID:17263354

  16. DeconMSn: A Software Tool for accurate parent ion monoisotopic mass determination for tandem mass spectra

    SciTech Connect

    Mayampurath, Anoop M.; Jaitly, Navdeep; Purvine, Samuel O.; Monroe, Matthew E.; Auberry, Kenneth J.; Adkins, Joshua N.; Smith, Richard D.

    2008-04-01

    We present a new software tool for tandem MS analyses that: • accurately calculates the monoisotopic mass and charge of high–resolution parent ions • accurately operates regardless of the mass selected for fragmentation • performs independent of instrument settings • enables optimal selection of search mass tolerance for high mass accuracy experiments • is open source and thus can be tailored to individual needs • incorporates a SVM-based charge detection algorithm for analyzing low resolution tandem MS spectra • creates multiple output data formats (.dta, .MGF) • handles .RAW files and .mzXML formats • compatible with SEQUEST, MASCOT, X!Tandem

  17. Z-scan theoretical and experimental studies for accurate measurements of the nonlinear refractive index and absorption of optical glasses near damage threshold

    NASA Astrophysics Data System (ADS)

    Olivier, Thomas; Billard, Franck; Akhouayri, Hassan

    2004-06-01

    Self-focusing is one of the dramatic phenomena that may occur during the propagation of a high power laser beam in a nonlinear material. This phenomenon leads to a degradation of the wave front and may also lead to a photoinduced damage of the material. Realistic simulations of the propagation of high power laser beams require an accurate knowledge of the nonlinear refractive index γ. In the particular case of fused silica and in the nanosecond regime, it seems that electronic mechanisms as well as electrostriction and thermal effects can lead to a significant refractive index variation. Compared to the different methods used to measure this parmeter, the Z-scan method is simple, offers a good sensitivity and may give absolute measurements if the incident beam is accurately studied. However, this method requires a very good knowledge of the incident beam and of its propagation inside a nonlinear sample. We used a split-step propagation algorithm to simlate Z-scan curves for arbitrary beam shape, sample thickness and nonlinear phase shift. According to our simulations and a rigorous analysis of the Z-scan measured signal, it appears that some abusive approximations lead to very important errors. Thus, by reducing possible errors on the interpretation of Z-scan experimental studies, we performed accurate measurements of the nonlinear refractive index of fused silica that show the significant contribution of nanosecond mechanisms.

  18. Experimental determination of group flux control coefficients in metabolic networks

    SciTech Connect

    Simpson, T.W.; Shimizu, Hiroshi; Stephanopoulos, G.

    1998-04-20

    Grouping of reactions around key metabolite branch points can facilitate the study of metabolic control of complex metabolic networks. This top-down Metabolic Control Analysis is exemplified through the introduction of group control coefficients whose magnitudes provide a measure of the relative impact of each reaction group on the overall network flux, as well as on the overall network stability, following enzymatic amplification. In this article, the authors demonstrate the application of previously developed theory to the determination of group flux control coefficients. Experimental data for the changes in metabolic fluxes obtained in response to the introduction of six different environmental perturbations are used to determine the group flux control coefficients for three reaction groups formed around the phosphoenolpyruvate/pyruvate branch point. The consistency of the obtained group flux control coefficient estimates is systematically analyzed to ensure that all necessary conditions are satisfied. The magnitudes of the determined control coefficients suggest that the control of lysine production flux in Corynebacterium glutamicum cells at a growth base state resides within the lysine biosynthetic pathway that begins with the PEP/PYR carboxylation anaplorotic pathway.

  19. Experimental determination of three dimensional liquid rocket nozzle admittances.

    NASA Technical Reports Server (NTRS)

    Zinn, B. T.; Bell, W. A.; Daniel, B. R.; Smith, A. J., Jr.

    1972-01-01

    The three dimensional nozzle admittance, an important parameter in combustion instability studies, was experimentally measured for several nozzle configurations. The admittance values were obtained using a modification of the classical impedance tube technique. The modified impedance tube method measures the admittance of a duct termination in the presence of one dimensional mean flow and three dimensional oscillations. Values of the nozzle admittance were obtained from pressure amplitude measurements taken at discrete points along the length of the tube. To determine the effects of nozzle geometry, nozzles were tested with half-angles of 15, 30, and 45 degrees and entrance Mach numbers of 0.08, 0.16, and 0.20. The admittance results are presented as functions of nondimensional frequency for mixed first tangential-longitudinal modes. These results are compared with available theoretical predictions and favorable agreement between theory and experiment is shown.

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

    PubMed

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

    2016-04-01

    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 mass index (BMI) among a multicultural sample of caregivers who were predominantly low-income and foreign-born.Methods A total of 980 caregivers (72% Hispanic, 71% born outside of the United States) of preschool-age children (N= 1,105) were asked if their child was normal weight, overweight, or obese. Answers were compared to actual child BMI percentile category via chi-square analysis. Logistic regression analysis was performed to assess predictors of accurate perception of child BMI percentile category.Results More than one third of preschoolers were either overweight (18.4%) or obese (16.5%). The majority (92%) of caregivers of an overweight/obese child inaccurately perceived that their child was in a normal BMI category. Overall, foreign-born caregivers were significantly less likely to accurately perceive their child's BMI percentile category versus U.S.-born caregivers (odds ratio [OR] = 0.65, 95% confidence interval [CI] = 0.48-0.88). Specifically, those born in South America (OR = 0.59, 95% CI = 0.36-0.98), Central America/Mexico (OR = 0.59, 95% CI = 0.41-0.85), and Caribbean Hispanic nations (OR = 0.54, 95% CI = 0.35-0.83) were significantly less likely to accurately perceive their child's BMI category versus U.S.-born caregivers.Conclusions The results of this study suggest that foreign-born caregivers of U.S. preschool-age overweight/obese children in particular do not accurately perceive their child's BMI status. Health care professionals serving foreign-born caregivers may consider additional culturally appropriate healthy weight counseling for these families. PMID:26304710

  1. 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

  2. Accurate determination of the superfluid-insulator transition in the one-dimensional Bose-Hubbard model

    NASA Astrophysics Data System (ADS)

    Zakrzewski, Jakub; Delande, Dominique

    2008-11-01

    The quantum phase transition point between the insulator and the superfluid phase at unit filling factor of the infinite one-dimensional Bose-Hubbard model is numerically computed with a high accuracy. The method uses the infinite system version of the time evolving block decimation algorithm, here tested in a challenging case. We provide also the accurate estimate of the phase transition point at double occupancy.

  3. 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

  4. Determination of gunshot residues with image analysis: an experimental study.

    PubMed

    Tuğcu, Harun; Yorulmaz, Coşkun; Bayraktaroğlu, Görgün; Uner, Hüseyin Bülent; Karslioğlu, Yildirim; Koç, Sermet; Ulukan, Mustafa Ozer; Celasun, Bülent

    2005-09-01

    In firearm injuries, assessment of the firing range and determination of entrance and exit wounds are important. For this reason, evaluation of the amount and distribution of gunshot residues (GSRs) is necessary. Several methods and techniques for GSR analysis have been developed. Although these methods are relatively sensitive and specific, they may require expensive dedicated equipment. Therefore, a simple, easily applicable, more convenient method is needed. A total of 40 experimental shots were made to calf skin from distances of 0, 2.5, 5, 10, 20, 30, 45, and 60 cm. Eighty samples were taken from the right and left sides of the wounds, and Alizarin Red S dye staining was performed. The amounts of GSR particles were measured with image analysis. GSRs were detected in all shots. The mean size of the distribution area of barium and lead elements around the wound had a significant negative correlation with increasing shooting distance (r = -0.97, p < 0.001). As the distance increased, the amount of GSR decreased, and this decrease rate was nonlinear. Variance analysis suggested significant differences between data groups depending on range (p < 0.001). The image analysis method may solve some of the standardization problems for evaluation of GSRs. GSR detection with the image analysis method does not require experienced personnel and may be a suitable method for scientific studies and for routine purposes. PMID:16261988

  5. Experimental determination of boron isotope fractionation in seawater

    NASA Astrophysics Data System (ADS)

    Klochko, K.; Kaufman, A. J.; Yao, W.; Byrne, R. H.; Tossell, J. A.

    2005-12-01

    The boron isotopic composition of marine carbonates is believed to be a useful tracer of seawater pH, which may then be used to reconstruct atmospheric pCO2 through time. Use of this proxy requires an intimate understanding of chemical kinetics and thermodynamic isotope exchange reactions between the two dominant boron-bearing species in seawater: boric acid B(OH)3 and borate ion B(OH)4-, which is preferentially incorporated into the carbonate lattice. However, due to our inability to quantitatively isolate these species from seawater, the magnitude of boron isotope fractionation at different temperatures and salinities has not previously been empirically measured. All paleo-pH studies have relied on the boron isotope equilibrium constant (11-10Kb = 1.0194 at 25°C) estimated theoretically in 1977 by Kakihana and colleagues. Here we present results of empirical determination of the boron isotope equilibrium constant at different temperatures and ionic strengths. The determinations are based on titration of isotopically labeled solutions, containing either 10B(OH)3 or 11B(OH)3, with NaOH. The pH of the titrated solutions is precisely measured using thymol blue indicator absorbance ratios. Differences in solution pH or, equivalently, borate/boric acid pK values between the isotopically substituted solutions, provides the desired equilibrium constant for the reaction: 10B(OH)3 + 11B(OH)4- <=> 11B(OH)3 + 10B(OH)4-. We have performed experiments to assess the influence of the temperature (25 and 40°C), ionic strength (0.05 and 0.7 molar) and medium composition (pure water, 0.6 M KCl, and synthetic seawater) on the isotopic equilibrium constant. Within experimental uncertainty maximum of ±0.002 (1σ), our results show only a weak dependence of the equilibrium constant on the above factors. The boron isotope equilibrium constant in seawater (S = 35) was determined to be 1.0269 ± 0.0013 at 25°C (1σ, n=6), which is in poor agreement with the theoretical basis for all

  6. A rapid, economical, and accurate method to determining the physical risk of storm marine inundations using sedimentary evidence

    NASA Astrophysics Data System (ADS)

    Nott, Jonathan F.

    2015-04-01

    The majority of physical risk assessments from storm surge inundations are derived from synthetic time series generated from short climate records, which can often result in inaccuracies and are time-consuming and expensive to develop. A new method is presented here for the wet tropics region of northeast Australia. It uses lidar-generated topographic cross sections of beach ridge plains, which have been demonstrated to be deposited by marine inundations generated by tropical cyclones. Extreme value theory statistics are applied to data derived from the cross sections to generate return period plots for a given location. The results suggest that previous methods to estimate return periods using synthetic data sets have underestimated the magnitude/frequency relationship by at least an order of magnitude. The new method promises to be a more rapid, economical, and accurate assessment of the physical risk of these events.

  7. A Simple Accurate Alternative to the Minimum-Deviation Method for the Determination of the Refractive Index of a Prism.

    ERIC Educational Resources Information Center

    Waldenstrom, S.; Naqvi, K. Razi

    1978-01-01

    Proposes an alternative to the classical minimum-deviation method for determining the refractive index of a prism. This new "fixed angle of incidence method" may find applications in research. (Author/GA)

  8. Experimental study on the application of a compressed-sensing (CS) algorithm to dental cone-beam CT (CBCT) for accurate, low-dose image reconstruction

    NASA Astrophysics Data System (ADS)

    Oh, Jieun; Cho, Hyosung; Je, Uikyu; Lee, Minsik; Kim, Hyojeong; Hong, Daeki; Park, Yeonok; Lee, Seonhwa; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

    2013-03-01

    In practical applications of three-dimensional (3D) tomographic imaging, there are often challenges for image reconstruction from insufficient data. In computed tomography (CT); for example, image reconstruction from few views would enable fast scanning with reduced doses to the patient. In this study, we investigated and implemented an efficient reconstruction method based on a compressed-sensing (CS) algorithm, which exploits the sparseness of the gradient image with substantially high accuracy, for accurate, low-dose dental cone-beam CT (CBCT) reconstruction. We applied the algorithm to a commercially-available dental CBCT system (Expert7™, Vatech Co., Korea) and performed experimental works to demonstrate the algorithm for image reconstruction in insufficient sampling problems. We successfully reconstructed CBCT images from several undersampled data and evaluated the reconstruction quality in terms of the universal-quality index (UQI). Experimental demonstrations of the CS-based reconstruction algorithm appear to show that it can be applied to current dental CBCT systems for reducing imaging doses and improving the image quality.

  9. 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

  10. Experimental and Theoretical Determination of Dissociation Energies of Dispersion-Dominated Aromatic Molecular Complexes.

    PubMed

    Frey, Jann A; Holzer, Christof; Klopper, Wim; Leutwyler, Samuel

    2016-05-11

    The dissociation energy (D0) of an isolated and cold molecular complex in the gas-phase is a fundamental measure of the strength of the intermolecular interactions between its constituent moieties. Accurate D0 values are important for the understanding of intermolecular bonding, for benchmarking high-level theoretical calculations, and for the parametrization of force-field models used in fields ranging from crystallography to biochemistry. We review experimental and theoretical methods for determining gas-phase D0 values of M·S complexes, where M is a (hetero)aromatic molecule and S is a closed-shell "solvent" atom or molecule. The experimental methods discussed involve M-centered (S0 → S1) electronic excitation, which is often followed by ionization to the M(+)·S ion. The D0 is measured by depositing a defined amount of vibrational energy in the neutral ground state, giving M(‡)·S, the neutral S1 excited state, giving M*·S, or the M(+)·S ion ground state. The experimental methods and their relative advantages and disadvantages are discussed. Based on the electronic structure of M and S, we classify the M·S complexes as Type I, II, or III, and discuss characteristic properties of their respective potential energy surfaces that affect or hinder the determination of D0. Current theoretical approaches are reviewed, which comprise methods based on a Kohn-Sham reference determinant as well as wave function-based methods based on coupled-cluster theory. PMID:27055105

  11. 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.

  12. 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.

  13. Photochemical parameters of atmospheric source gases: accurate determination of OH reaction rate constants over atmospheric temperatures, UV and IR absorption spectra

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Khamaganov, V. G.; Martynova, L. E.; Kurylo, M. J.

    2012-12-01

    The emissions of halogenated (Cl, Br containing) organics of both natural and anthropogenic origin contribute to the balance of and changes in the stratospheric ozone concentration. The associated chemical cycles are initiated by the photochemical decomposition of the portion of source gases that reaches the stratosphere. Reactions with hydroxyl radicals and photolysis are the main processes dictating the compound lifetime in the troposphere and release of active halogen in the stratosphere for a majority of halogen source gases. Therefore, the accuracy of photochemical data is of primary importance for the purpose of comprehensive atmospheric modeling and for simplified kinetic estimations of global impacts on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP). The sources of critically evaluated photochemical data for atmospheric modeling, NASA/JPL Publications and IUPAC Publications, recommend uncertainties within 10%-60% for the majority of OH reaction rate constants with only a few cases where uncertainties lie at the low end of this range. These uncertainties can be somewhat conservative because evaluations are based on the data from various laboratories obtained during the last few decades. Nevertheless, even the authors of the original experimental works rarely estimate the total combined uncertainties of the published OH reaction rate constants to be less than ca. 10%. Thus, uncertainties in the photochemical properties of potential and current atmospheric trace gases obtained under controlled laboratory conditions still may constitute a major source of uncertainty in estimating the compound's environmental impact. One of the purposes of the presentation is to illustrate the potential for obtaining accurate laboratory measurements of the OH reaction rate constant over the temperature range of atmospheric interest. A detailed inventory of accountable sources of

  14. 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. PMID:27095534

  15. Technical Note: How accurate can stalagmite formation temperatures be determined using vapour bubble radius measurements in fluid inclusions?

    NASA Astrophysics Data System (ADS)

    Spadin, F.; Marti, D.; Hidalgo-Staub, R.; Rička, J.; Fleitmann, D.; Frenz, M.

    2015-06-01

    Stalagmites are natural archives containing detailed information on continental climate variability of the past. Microthermometric measurements of fluid inclusion homogenisation temperatures allow determination of stalagmite formation temperatures by measuring the radius of stable laser-induced vapour bubbles inside the inclusions. A reliable method for precisely measuring the radius of vapour bubbles is presented. The method is applied to stalagmite samples for which the formation temperature is known. An assessment of the bubble radius measurement accuracy and how this error influences the uncertainty in determining the formation temperature is provided. We demonstrate that the nominal homogenisation temperature of a single inclusion can be determined with an accuracy of ±0.25 °C, if the volume of the inclusion is larger than 105 μm3. With this method, we could measure in a proof-of-principle investigation that the formation temperature of 10-20 yr old inclusions in a stalagmite taken from the Milandre cave is 9.87 ± 0.80 °C, while the mean annual surface temperature, that in the case of the Milandre cave correlates well with the cave temperature, was 9.6 ± 0.15 °C, calculated from actual measurements at that time, showing a very good agreement. Formation temperatures of inclusions formed during the last 450 yr are found in a temperature range between 8.4 and 9.6 °C, which corresponds to the calculated average surface temperature. Paleotemperatures can thus be determined within ±1.0 °C.

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

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Li, Bincheng

    2015-12-01

    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.

  17. 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.

  18. 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

  19. 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.

  20. 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...

  1. Accurate quantitative 13C NMR spectroscopy: repeatability over time of site-specific 13C isotope ratio determination.

    PubMed

    Caytan, Elsa; Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Remaud, Gérald S

    2007-11-01

    The stability over time (repeatability) for the determination of site-specific 13C/12C ratios at natural abundance by quantitative 13C NMR spectroscopy has been tested on three probes: enriched bilabeled [1,2-13C2]ethanol; ethanol at natural abundance; and vanillin at natural abundance. It is shown in all three cases that the standard deviation for a series of measurements taken every 2-3 months over periods between 9 and 13 months is equal to or smaller than the standard deviation calculated from 5-10 replicate measurements made on a single sample. The precision which can be achieved using the present analytical 13C NMR protocol is higher than the prerequisite value of 1-2 per thousand for the determination of site-specific 13C/12C ratios at natural abundance (13C-SNIF-NMR). Hence, this technique permits the discrimination of very small variations in 13C/12C ratios between carbon positions, as found in biogenic natural products. This observed stability over time in 13C NMR spectroscopy indicates that further improvements in precision will depend primarily on improved signal-to-noise ratio. PMID:17900175

  2. A simple method for the accurate determination of the Henry's law constant for highly sorptive, semivolatile organic compounds.

    PubMed

    Kim, Yong-Hyun; Kim, Ki-Hyun

    2016-01-01

    A novel technique is developed to determine the Henry's law constants (HLCs) of seven volatile fatty acids (VFAs) with significantly high solubility using a combined application of thermal desorber/gas chromatography/mass spectrometry (TD/GC/MS). In light of the strong sorptive properties of these semi-volatile organic compounds (SVOCs), their HLCs were determined by properly evaluating the fraction lost on the surface of the materials used to induce equilibrium (vial, gas-tight syringe, and sorption tube). To this end, a total of nine repeated experiments were conducted in a closed (static) system at three different gas/liquid volume ratios. The best estimates for HLCs (M/atm) were thus 7,200 (propionic acid), 4,700 (i-butyric acid), 4,400 (n-butyric acid), 2,700 (i-valeric acid), 2,400 (n-valeric acid), 1,000 (hexanoic acid), and 1,500 (heptanoic acid). The differences in the HLC values between this study and previous studies, if assessed in terms of the percent difference, ranged from 9.2% (n-valeric acid) to 55.7% (i-valeric acid). We overcame the main cause of errors encountered in previous studies by performing the proper correction of the sorptive losses of the SVOCs that inevitably took place, particularly on the walls of the equilibration systems (mainly the headspace vial and/or the glass tight syringe). PMID:26577086

  3. Accurate mass determination for double-lined spectroscopic binaries by digital cross-correlation spectroscopy: DM Virginis revisited.

    NASA Astrophysics Data System (ADS)

    Latham, D. W.; Nordstroem, B.; Andersen, J.; Torres, G.; Stefanik, R. P.; Thaller, M.; Bester, M. J.

    1996-10-01

    Fundamental mass determinations in eclipsing binaries rely on radial velocities derived from double-lined spectra. We evaluate the performance of the CfA Digital Speedometers for deriving radial velocities of double-lined systems, using simulated observations of composite spectra. When XCSAO (Kurtz et al. 1992) is used to calculate a one-dimensional cross-correlation, simple fits to the double peaks in the correlation function can lead to systematic errors as large as 3km/s due to the effects of line blending. The two-dimensional correlation scheme TODCOR (Zucker & Mazeh 1994ApJ...420..806Z) can reduce the systematic errors by an order of magnitude. We apply TODCOR to a new mass determination for the F-type eclipsing binary DM Vir, achieving an accuracy of 0.6%. The improved physical properties of DM Vir agree very well with stellar evolution models incorporating the most recent opacity data, both with and without convective core overshooting, and for reasonable assumptions about the chemical composition. The age of DM Vir is found to be 1.75+/-0.20x10^9^yr, metallicity being the dominant source of uncertainty.

  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. Development of an experimental apparatus and protocol for determining antimicrobial activities of gaseous plant essential oils.

    PubMed

    Seo, Hyun-Sun; Beuchat, Larry R; Kim, Hoikyung; Ryu, Jee-Hoon

    2015-12-23

    There is a growing interest in the use of naturally-occurring antimicrobial agents such as plant essential oils (EOs) to inhibit the growth of hazardous and spoilage microorganisms in foods. Gaseous EOs (EO gases) have many potential applications in the food industry, including use as antimicrobial agents in food packaging materials and sanitizing agents for foods and food-contact surfaces, and in food processing environments. Despite the potentially beneficial applications of EO gases, there is no standard method to evaluate their antimicrobial activities. Thus, the present study was aimed at developing an experimental apparatus and protocol to determine the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) of EO gases against microorganisms. A sealed experimental apparatus was constructed for simultaneous evaluation of antimicrobial activities of EO gases at different concentrations without creating concentration gradients. A differential medium was then evaluated in which a color change allowed for the determination of growth of glucose-fermenting microorganisms. Lastly, an experimental protocol for the assessment of MIC and MLC values of EO gases was developed, and these values were determined for 31 EO gases against Escherichia coli O157:H7 as a model bacterium. Results showed that cinnamon bark EO gas had the lowest MIC (0.0391 μl/ml), followed by thyme-thymol EO gas (0.0781 μl/ml), oregano EO gas (0.3125 μl/ml), peppermint EO gas (0.6250 μl/ml), and thyme-linalool EO gas (0.6250 μl/ml). The order of the MLC values of the EO gases against the E. coli O157:H7 was thyme-thymol (0.0781 μl/ml)experimental apparatus and protocol enable rapid and accurate determination of the MIC and MLC values of EO gases and perhaps other types of gaseous antimicrobial agents. PMID:26350124

  6. Accurate determination of the scattering length of metastable helium atoms using dark resonances between atoms and exotic molecules.

    PubMed

    Moal, S; Portier, M; Kim, J; Dugué, J; Rapol, U D; Leduc, M; Cohen-Tannoudji, C

    2006-01-20

    We present a new measurement of the s-wave scattering length a of spin-polarized helium atoms in the 2(3)S1 metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy E(nu)=14= -91.35+/- 0.06 MHz of the least-bound state nu = 14 in the interaction potential of the two atoms. We deduce a value of a=7.512+/-0.005 nm, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of 1 micros. PMID:16486572

  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. PMID:24144617

  8. Time-Dependent Reversible-Irreversible Deformation Threshold Determined Explicitly by Experimental Technique

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.; Arnold, Steven M.

    2000-01-01

    Structural materials for the design of advanced aeropropulsion components are usually subject to loading under elevated temperatures, where a material's viscosity (resistance to flow) is greatly reduced in comparison to its viscosity under low-temperature conditions. As a result, the propensity for the material to exhibit time-dependent deformation is significantly enhanced, even when loading is limited to a quasi-linear stress-strain regime as an effort to avoid permanent (irreversible) nonlinear deformation. An understanding and assessment of such time-dependent effects in the context of combined reversible and irreversible deformation is critical to the development of constitutive models that can accurately predict the general hereditary behavior of material deformation. To this end, researchers at the NASA Glenn Research Center at Lewis Field developed a unique experimental technique that identifies the existence of and explicitly determines a threshold stress k, below which the time-dependent material deformation is wholly reversible, and above which irreversible deformation is incurred. This technique is unique in the sense that it allows, for the first time, an objective, explicit, experimental measurement of k. The underlying concept for the experiment is based on the assumption that the material s time-dependent reversible response is invariable, even in the presence of irreversible deformation.

  9. 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.

  10. Determining the performance of energy wheels: Part 1 -- Experimental and numerical methods

    SciTech Connect

    Simonson, C.J.; Ciepliski, D.L.; Besant, R.W.

    1999-07-01

    Measuring and modeling the performance of energy recovery devices is difficult and, in some cases, may result in unacceptably high uncertainties. In this paper, controlled laboratory experiments and a detailed numerical model are presented, which, together with uncertainty analysis, can quantify the performance of energy wheels. A numerical model that has been developed from physical principles and an experimental method for determining the performance of energy wheels with acceptable uncertainties are detailed. Included is a pre-test, during-test, and post-test uncertainty analysis that allows the experimenter to estimate accurately precision (random) and bias (fixed) errors a priori, during, and a posteriori each experiment using energy and mass balances on the air-to-air energy recovery device as well as the characteristics of each instrument and the data acquisition system. A comprehensive set of measured data for the sensible, latent, and total effectiveness of an energy wheel is compared with the corresponding simulation results in Part 2 of this paper.

  11. Cigarette Experimentation in Mexican Origin Youth: Psychosocial and Genetic Determinants

    PubMed Central

    Wilkinson, Anna V.; Bondy, Melissa L.; Wu, Xifeng; Wang, Jian; Dong, Qiong; D’Amelio, Anthony M.; Prokhorov, Alexander V.; Pu, Xia; Yu, Robert K.; Etzel, Carol J.; Shete, Sanjay; Spitz, Margaret R.

    2011-01-01

    Background Established psychosocial risk factors increase the risk for experimentation among Mexican-origin youth. Now we comprehensively investigate the added contribution of select polymorphisms in candidate genetic pathways associated with sensation seeking, risk taking, and smoking phenotypes to predict experimentation. Methods Participants, (N=1,118 Mexican origin youth) recruited from a large population-based cohort study in Houston, Texas, provided prospective data on cigarette experimentation over three years. Psychosocial data were elicited twice—baseline and final follow-up. Participants were genotyped for 672 functional and tagging variants in the dopamine, serotonin and opioid pathways. Results After adjusting for gender and age, with a Bayesian False Discovery Probability set at 0.8 and prior probability of 0.05, six gene variants were significantly associated with risk of experimentation. After controlling for established risk factors, multivariable analyses revealed that participants with six or more risk alleles were 2.25 (95%CI: 1.62–3.13) times more likely to have experimented since baseline compared to participants with five or fewer. Among committed never smokers (N=872), three genes (OPRM1, SNAP25, HTR1B) were associated with experimentation as were all psychosocial factors. Among susceptible youth (N=246) older age at baseline, living with a smoker, and three different genes (HTR2A, DRD2, SLC6A3) predicted experimentation. Conclusions Our findings, which have implications for development of culturally-specific interventions, need to be validated in other ethnic groups. Impact These results suggest that variations in select genes interact with a cognitive predisposition toward smoking. In susceptible adolescents, the impact of the genetic variants appears to be larger compared to committed never smokers. PMID:22028400

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

    PubMed

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

    2012-06-01

    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

  13. 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

  14. Experimentally determined water storage capacity in the Earth's upper mantle

    NASA Astrophysics Data System (ADS)

    Ferot, A.; Bolfan-Casanova, N.

    2010-12-01

    Trace amounts of hydrogen dissolved as defects in nominally anhydrous minerals (NAMs) in the mantle are believed to play a key role in physical and chemical processes in the Earth’s upper mantle. Hence, the estimation of water storage in mantle phases and solubility mechanisms are important in order to better understand the effect of water. Experimental data on water solubility in NAMs are available for upper mantle minerals such as olivine, pyroxenes and garnet. However, the majority of studies are based on the study of single phases, and at temperatures or pressures that are too low for the Earth’s upper mantle. The aim of this study is to constrain the combined effects of pressure, temperature and composition on water solubility in olivine and orthopyroxene under upper mantle conditions. The solubility of water in coexisting orthopyroxene and olivine was investigated by simultaneously synthesizing the two phases at high pressure and high temperature in a multi-anvil press. Experiments were performed under water-saturated conditions in the MSH systems with Fe and Al at 2.5, 5, 7.5 and 9 GPa and temperatures between 1175 and 1400°C. Integrated OH absorbances were determined using polarized infrared spectroscopy on doubly polished thin sections of randomly oriented crystals. Water solubility in olivine increases with pressure and decreases with temperature as has been described previously (Bali et al., 2008). The aluminum content strongly decreases in olivine with pressure from 0.09 wt% at 2.5 GPa and 1250°C to 0.04 wt% at 9 GPa and 1175°C. The incorporation of this trivalent cation in the system enhances water solubility in olivine even if present in trace amounts, however this behavior appears to reverse at high pressure. The effect of temperature on water solubility follows a bell-shaped curve with a maximum solubility in olivine and orthopyroxene at 1250°C. Aluminum is incorporated in orthopyroxene following the Tschermak substitution and strongly

  15. Accurate determination of interface trap state parameters by admittance spectroscopy in the presence of a Schottky barrier contact: Application to ZnO-based solar cells

    NASA Astrophysics Data System (ADS)

    Marin, Andrew T.; Musselman, Kevin P.; MacManus-Driscoll, Judith L.

    2013-04-01

    This work shows that when a Schottky barrier is present in a photovoltaic device, such as in a device with an ITO/ZnO contact, equivalent circuit analysis must be performed with admittance spectroscopy to accurately determine the pn junction interface recombination parameters (i.e., capture cross section and density of trap states). Without equivalent circuit analysis, a Schottky barrier can produce an error of ˜4-orders of magnitude in the capture cross section and ˜50% error in the measured density of trap states. Using a solution processed ZnO/Cu2O photovoltaic test system, we apply our analysis to clearly separate the contributions of interface states at the pn junction from the Schottky barrier at the ITO/ZnO contact so that the interface state recombination parameters can be accurately characterized. This work is widely applicable to the multitude of photovoltaic devices, which use ZnO adjacent to ITO.

  16. Accurate Cytotoxicity and Proliferation Determination: Advantages of a High-Throughput Phenotypic Approach Over ATP Luminescence Assays.

    PubMed

    Hammerstein, Anne F; Wylie, Paul G

    2016-09-01

    Cell viability and proliferation assays are a fundamental tool in the drug discovery process and are used to evaluate both the antiproliferative potency and toxicity of compounds. Some lead discovery groups generate cell viability data for up to two million compounds per screen, so any method used to assess these parameters needs to deliver not only on data quality but also on throughput and assay cost per well. Most methods used to determine cell viability cannot deliver on all three of these requirements, so compromises have to be made. Here we show the development and implementation of a cost-effective, no-wash phenotypic assay to simultaneously report the number of cells, percentage of live cells, and cell cycle phase distribution as markers of proliferation and viability. We demonstrate that this assay can be applied to high-density plate formats and be imaged and analyzed in 8 min per plate on a laser scanning imaging cytometer. By comparing the drug-responses of several well-characterized anticancer drugs on HeLa cells, we highlight the key differences between the phenotypic assay and a commercial ATP luminescence detection system. PMID:27504922

  17. 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. PMID:26212984

  18. AN EFFICIENT METHOD FOR ACCURATELY DETERMINING WEAR VOLUMES OF SLIDERS WITH NON-FLAT WEAR SCARS AND COMPOUND CURVATURES

    SciTech Connect

    Qu, Jun; Truhan, Jr., John J

    2006-01-01

    Point contact is often used in unidirectional pin-on-disk and reciprocating pin-on-flat sliding friction and wear tests. The slider tip could have either a spherical shape or compound curvatures (such as an ellipsoidal shape), and the worn tip usually is not flat but has unknown curvatures. Current methods for determining the wear volumes of sliders suffer from one or more limitations. For example, the gravimetric method is not able to detect small amounts of wear, and the two-dimensional wear scar size measurement is valid only for flat wear scars. More rigorous methods can be very time consuming, such as the 3D surface profiling method that involves obtaining tedious multiple surface profiles and analyzing a large set of data. In this study, a new 'single-trace' analysis is introduced to efficiently evaluate the wear volumes of non-flat worn sliders. This method requires only the measurement of the wear scar size and one trace of profiling to obtain the curvature on the wear cap. The wear volume calculation only involves closed-form algebraic equations. This single-trace method has demonstrated much higher accuracy and fewer limitations than the gravimetric method and 2D method, and has shown good agreement with the 3D method while saving significant surface profiling and data analysis time.

  19. Radioligand binding assay for accurate determination of nuclear retinoid X receptors: A case of triorganotin endocrine disrupting ligands.

    PubMed

    Toporova, Lucia; Macejova, Dana; Brtko, Julius

    2016-07-01

    Nuclear 9-cis retinoic acid receptors (retinoid X receptors, RXR) are promiscuous dimerization partners for a number of nuclear receptors. In the present study, we established a novel in vitro method for quantitative determination of the nuclear retinoid X receptors in rat liver. One type of high affinity and limited capacity RXR specific binding sites with the Ka value ranging from 1.011 to 1.727×10(9)l/mol and the Bmax value ranging from 0.346 to 0.567pmol/mg, was demonstrated. Maximal 9-cis retinoic acid (9cRA) specific binding to nuclear retinoid X receptors was achieved at 20°C, and the optimal incubation time for the 9cRA-RXR complex formation was 120min. From a number of endocrine disruptors, tributyltins and triphenyltins are known as RXR ligands. Our data confirmed the property of tributyltin chloride or triphenyltin chloride to bind to a high affinity and limited capacity RXR binding sites. Described optimal conditions for ligand binding to RXR molecules enabled us to calculate maximal binding capacity (Bmax) and affinity (Ka) values. This study provides an original RXR radioligand binding assay that can be employed for investigation of novel RXR ligands that comprise both drugs and endocrine disruptors. PMID:27153798

  20. Aluminum Silicate System: Experimental Determination of the Triple Point.

    PubMed

    Bell, P M

    1963-03-15

    The kyanite-sillimanite-andalusite triple point exists in the pressure-temperature plane at 8 +/- 0.5 kb and 300 +/- 50 degrees C. Reactions are accomplished experimentally with a Bridgman opposed-anvil press (with an external furnace), modified to provide shearing of the sample charges. All three equilibrium boundaries are proved by reversed reactions. PMID:17812984

  1. 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.

  2. 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

  3. Direct determination of the hit locations from experimental HPGe pulses

    NASA Astrophysics Data System (ADS)

    Désesquelles, P.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Dimmock, M. R.; Lazarus, I. H.; Ljungvall, J.; Nelson, L.; Nga, D.-T.; Nolan, P. J.; Rigby, S. V.; Simpson, J.; Van-Oanh, N.-T.

    2013-11-01

    The gamma-tracking technique optimises the determination of the energy and emission angle of gamma-rays detected by modern segmented HPGe detectors. This entails the determination, using the delivered pulse shapes, of the interaction points of the gamma-ray within the crystal. The direct method presented here allows the localisation of the hits using only a large sample of pulses detected in the actual operating conditions. No external crystal scanning system or pulse shape simulation code is needed. In order to validate this method, it is applied to sets of pulses obtained using the University of Liverpool scanning system. The hit locations are determined by the method with good precision.

  4. Experimental and Numerical Studies on Determination of Indirect Tensile Strength of Rocks

    NASA Astrophysics Data System (ADS)

    Erarslan, Nazife; Liang, Zheng Zhao; Williams, David John

    2012-09-01

    Indirect tension tests using Brisbane tuff Brazilian disc specimens under standard Brazilian jaws and various loading arcs were performed. The standard Brazilian indirect tensile tests caused catastrophic, crushing failure of the disc specimens, rather than the expected tensile splitting failure initiated by a central crack. This led to an investigation of the fracturing of Brazilian disc specimens and the existing indirect tensile Brazilian test using steel loading arcs with different angles. The results showed that the ultimate failure load increased with increasing loading arc angles. With no international standard for determining indirect tensile strength of rocks under diametral load, numerical modelling and analytical solutions were undertaken. Numerical simulations using RFPA2D software were conducted with a heterogeneous material model. The results predicted tensile stress in the discs and visually reproduced the progressive fracture process. It was concluded that standard Brazilian jaws cause catastrophic, crushing failure of the disc specimens instead of producing a central splitting crack. The experimental and numerical results showed that 20° and 30° loading arcs result in diametral splitting fractures starting at the disc centre. Moreover, intrinsic material properties (e.g. fracture toughness) may be used to propose the best loading configuration to determine the indirect tensile strength of rocks. Here, by using numerical outcomes and empirical relationships between fracture toughness and tensile strength, the best loading geometry to obtain the most accurate indirect tensile strength of rocks was the 2α = 30° loading arc.

  5. Experimental determination of the effective strong coupling constant

    SciTech Connect

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

    2005-09-15

    We extract an effective strong coupling constant from low Q2 data on the Bjorken sum. Using sum rules, we establish its Q2-behavior over the complete Q2-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.

  6. Experimental Determination of Multipartite Entanglement with Incomplete Information

    NASA Astrophysics Data System (ADS)

    Aguilar, G. H.; Walborn, S. P.; Ribeiro, P. H. Souto; Céleri, L. C.

    2015-07-01

    Multipartite entanglement is very poorly understood despite all the theoretical and experimental advances of the last decades. Preparation, manipulation, and identification of this resource is crucial for both practical and fundamental reasons. However, the difficulty in the practical manipulation and the complexity of the data generated by measurements on these systems increase rapidly with the number of parties. Therefore, we would like to experimentally address the problem of how much information about multipartite entanglement we can access with incomplete measurements. In particular, it was shown that some types of pure multipartite entangled states can be witnessed without measuring the correlations [M. Walter et al., Science 340, 1205 (2013)] between parties, which is strongly demanding experimentally. We explore this method using an optical setup that permits the preparation and the complete tomographic reconstruction of many inequivalent classes of three- and four-partite entangled states, and compare complete versus incomplete information. We show that the method is useful in practice, even for nonpure states or nonideal measurement conditions.

  7. 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.

  8. 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.

  9. Determination of Young’s modulus by studying the flexural vibrations of a bar: experimental and theoretical approaches

    NASA Astrophysics Data System (ADS)

    Pradhan, R.; Dhara, A. K.; Panchadhyayee, P.; Syam, D.

    2016-01-01

    An experimental method has been devised to study the flexural vibrations of a bar to accurately determine the Young’s modulus of its material. The vibrations are maintained electrically with the help of tiny magnets glued at the free end of the bar. The distinctive element in the present work is the determination of higher resonant frequencies with notable accuracy along with the fundamental. The actual values of the resonant frequencies in zero magnet-mass condition are obtained from the extrapolated plots of the observed resonant frequencies versus the mass of the magnet. A theoretical model is also developed for the fundamental mode based upon which numerical results are obtained and found to be in conformity with these experimental findings.

  10. 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.

  11. Determining the extent of coarticulation: effects of experimental design.

    PubMed

    Gelfer, C E; Bell-Berti, F; Harris, K S

    1989-12-01

    The purpose of this letter is to explore some reasons for what appear to be conflicting reports regarding the nature and extent of anticipatory coarticulation, in general, and anticipatory lip rounding, in particular. Analyses of labial electromyographic and kinematic data using a minimal-pair paradigm allowed for the differentiation of consonantal and vocalic effects, supporting a frame versus a feature-spreading model of coarticulation. It is believed that the apparent conflicts of previous studies of anticipatory coarticulation might be resolved if experimental design made more use of contrastive minimal pairs and relied less on assumptions about feature specifications of phones. PMID:2600314

  12. Accurate blackbodies

    NASA Astrophysics Data System (ADS)

    Latvakoski, Harri M.; Watson, Mike; Topham, Shane; Scott, Deron; Wojcik, Mike; Bingham, Gail

    2010-07-01

    Infrared radiometers and spectrometers generally use blackbodies for calibration, and with the high accuracy needs of upcoming missions, blackbodies capable of meeting strict accuracy requirements are needed. One such mission, the NASA climate science mission Climate Absolute Radiance and Refractivity Observatory (CLARREO), which will measure Earth's emitted spectral radiance from orbit, has an absolute accuracy requirement of 0.1 K (3σ) at 220 K over most of the thermal infrared. Space Dynamics Laboratory (SDL) has a blackbody design capable of meeting strict modern accuracy requirements. This design is relatively simple to build, was developed for use on the ground or onorbit, and is readily scalable for aperture size and required performance. These-high accuracy blackbodies are currently in use as a ground calibration unit and with a high-altitude balloon instrument. SDL is currently building a prototype blackbody to demonstrate the ability to achieve very high accuracy, and we expect it to have emissivity of ~0.9999 from 1.5 to 50 μm, temperature uncertainties of ~25 mK, and radiance uncertainties of ~10 mK due to temperature gradients. The high emissivity and low thermal gradient uncertainties are achieved through cavity design, while the low temperature uncertainty is attained by including phase change materials such as mercury, gallium, and water in the blackbody. Blackbody temperature sensors are calibrated at the melt points of these materials, which are determined by heating through their melt point. This allows absolute temperature calibration traceable to the SI temperature scale.

  13. Experimental Determination of Thermal Conductivity of Low-Density Ice

    NASA Technical Reports Server (NTRS)

    Coles, Willard D.

    1954-01-01

    The thermal conductivity of low-density ice has been computed from data obtained in an experimental investigation of the heat transfer and mass transfer by sublimation for an iced surface on a flat plate in a high-velocity tangential air stream. The results are compared with data from several sources on the thermal conductivity of packed snow and solid glaze ice. The results show good agreement with the equations for the thermal conductivity of packed snow as a function of snow density. The agreement of the curves for packed snow near the solid ice regime with the values of thermal conductivity, of ice indicates that the curves are applicable over the entire-ice-density range.

  14. 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.

  15. Experimental determination of a Viviparus contectus thermometry equation.

    PubMed

    Bugler, Melanie J; Grimes, Stephen T; Leng, Melanie J; Rundle, Simon D; Price, Gregory D; Hooker, Jerry J; Collinson, Margaret E

    2009-09-01

    Experimental measurements of the (18)O/(16)O isotope fractionation between the biogenic aragonite of Viviparus contectus (Gastropoda) and its host freshwater were undertaken to generate a species-specific thermometry equation. The temperature dependence of the fractionation factor and the relationship between Deltadelta(18)O (delta(18)O(carb.) - delta(18)O(water)) and temperature were calculated from specimens maintained under laboratory and field (collection and cage) conditions. The field specimens were grown (Somerset, UK) between August 2007 and August 2008, with water samples and temperature measurements taken monthly. Specimens grown in the laboratory experiment were maintained under constant temperatures (15 degrees C, 20 degrees C and 25 degrees C) with water samples collected weekly. Application of a linear regression to the datasets indicated that the gradients of all three experiments were within experimental error of each other (+/-2 times the standard error); therefore, a combined (laboratory and field data) correlation could be applied. The relationship between Deltadelta(18)O (delta(18)O(carb.) - delta(18)O(water)) and temperature (T) for this combined dataset is given by: T = - 7.43( + 0.87, - 1.13)*Deltadelta18O + 22.89(+/- 2.09) (T is in degrees C, delta(18)O(carb.) is with respect to Vienna Pee Dee Belemnite (VPDB) and delta(18)O(water) is with respect to Vienna Standard Mean Ocean Water (VSMOW). Quoted errors are 2 times standard error).Comparisons made with existing aragonitic thermometry equations reveal that the linear regression for the combined Viviparus contectus equation is within 2 times the standard error of previously reported aragonitic thermometry equations. This suggests there are no species-specific vital effects for Viviparus contectus. Seasonal delta(18)O(carb.) profiles from specimens retrieved from the field cage experiment indicate that during shell secretion the delta(18)O(carb.) of the shell carbonate is not influenced by

  16. 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.

  17. Statistically deformable 2D/3D registration for accurate determination of post-operative cup orientation from single standard X-ray radiograph.

    PubMed

    Zheng, Guoyan

    2009-01-01

    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 rigid 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 a pre-operative CT scan, which is not available for most retrospective studies. To address these issues, we developed and validated a statistically deformable 2D/3D registration approach for accurate determination of post-operative cup orientation. No CAD model and pre-operative CT data is required any more. Quantitative and qualitative results evaluated on cadaveric and clinical datasets are given, which indicate the validity of the approach. PMID:20426064

  18. Experimentally determined chaotic phase synchronization in a neuronal system

    PubMed Central

    Makarenko, Vladimir; Llinás, Rodolfo

    1998-01-01

    Mathematical analysis of the subthreshold oscillatory properties of inferior olivary neurons in vitro indicates that the oscillation is nonlinear and supports low dimensional chaotic dynamics. This property leads to the generation of complex functional states that can be attained rapidly via phase coherence that conform to the category of “generalized synchronization.” Functionally, this translates into neuronal ensemble properties that can support maximum functional permissiveness and that rapidly can transform into robustly determined multicellular coherence. PMID:9861041

  19. Experimental infrared measurements for hydrocarbon pollutant determination in subterranean waters

    NASA Astrophysics Data System (ADS)

    Lay-Ekuakille, A.; Palamara, I.; Caratelli, D.; Morabito, F. C.

    2013-01-01

    Subterranean waters are often polluted by industrial and anthropic effluents that are drained in subsoil. To prevent and control pollution, legislations of different developed countries require an online monitoring measurement, especially for detecting organic solvents (chlorinated and unchlorinated ones). Online measurements include both real-time and no real-time measurements. In general, it is difficult to implement real-time measurements in stricto sensu for online acquisitions on aqueous effluents since they need to be processed by a modeling. This research presents an experimental measurement system based on infrared (IR) spectroscopy for aqueous effluents containing hydrocarbons and capable of displaying excellent values of pollutant concentrations even in instable conditions; the system is able to detect pollutants either in laminar or turbulent flow. The results show the possibility of avoiding the use of "Pitot tube" that is employed to create a stagnation point in order to convert kinetic energy into potential one. This conversion allows the transformation of a turbulent flow in a laminar flow making easy measurement of pollutants included in an aqueous effluent. Obviously, "Pitot tube" is also used for other fluid effluents. The obtained results have been compared with those produced by means of sophisticated IR instrumentation for laboratory applications.

  20. The Microbiota Determines Susceptibility to Experimental Autoimmune Uveoretinitis

    PubMed Central

    Heissigerova, Jarmila; Seidler Stangova, Petra; Klimova, Aneta; Svozilkova, Petra; Hrncir, Tomas; Stepankova, Renata; Kverka, Miloslav; Tlaskalova-Hogenova, Helena; Forrester, John V.

    2016-01-01

    The microbiota is a crucial modulator of the immune system. Here, we evaluated how its absence or reduction modifies the inflammatory response in the murine model of experimental autoimmune uveoretinitis (EAU). We induced EAU in germ-free (GF) or conventionally housed (CV) mice and in CV mice treated with a combination of broad-spectrum antibiotics either from the day of EAU induction or from one week prior to induction of disease. The severity of the inflammation was assessed by fundus biomicroscopy or by histology, including immunohistology. The immunophenotyping of T cells in local and distant lymph nodes was performed by flow cytometry. We found that GF mice and mice where the microbiota was reduced one week before EAU induction were protected from severe autoimmune inflammation. GF mice had lower numbers of infiltrating macrophages and significantly less T cell infiltration in the retina than CV mice with EAU. GF mice also had reduced numbers of IFN-γ and IL-17-producing T cells and increased numbers of regulatory T cells in the eye-draining lymph nodes. These data suggest that the presence of microbiota during autoantigen recognition regulates the inflammatory response by influencing the adaptive immune response. PMID:27294159

  1. Experimental determination of fragment excitation energies in multifragmentation events

    SciTech Connect

    Marie, N.; Natowitz, J.B.; Cibor, J.; Hagel, K.; Wada, R.; Chbihi, A.; Le Fevre, A.; Salou, S.; Wieleczko, J.P.; Gingras, L.; Auger, G.; Laville, J.L.; Saint-Laurent, F.; Tirel, O.; Assenard, M.; Eudes, P.; Germain, M.; Rahmani, A.; Reposeur, T.; Bacri, C.O.; Borderie, B.; Frankland, J.D.; Plagnol, E.; Rivet, M.F.; Bocage, F.; Bougault, R.; Brou, R.; Colin, J.; Cussol, D.; Durand, D.; Genouin-Duhamel, E.; Lecolley, J.F.; Lefort, T.; Le Neindre, N.; Lopez, O.; Louvel, M.; Nguyen, A.D.; Peter, J.; Steckmeyer, J.C.; Tamain, B.; Vient, E.; Buchet, P.; Charvet, J.L.; Dayras, R.; Dore, D.; Legrain, R.; Nalpas, L.; Volant, C.; Parlog, M.; Tabacaru, G.; Rosato, E.; Gourio, D.; Majka, Z.

    1998-07-01

    For 50 MeV/nucleon {sup 129}Xe+{sup nat}Sn multifragmentation events, we deduced, by means of correlation techniques, the multiplicities of the hydrogen and helium isotopes which were emitted by the hot primary excited fragments produced at the stage of the disassembly of an equilibrated hot source. We also derived the relative kinetic energy distributions between the primary clusters and the light charged particles that they evaporate. From the comparison between the secondary multiplicities observed experimentally and the multiplicities predicted by the GEMINI model, we concluded that the source breaks into primary fragments which are characterized by the same N/Z ratio as the combined system. Knowing the secondary light charged particle multiplicities and kinetic energies, we reconstructed the average charges of the hot fragments and we estimated their mean excitation energies. The fragment excitation energies are equal to 3.0 MeV/nucleon for the full range of intermediate mass fragment atomic number. This global constancy indicates that, on the average, thermodynamical equilibrium was achieved at the disassembly stage of the source. {copyright} {ital 1998} {ital The American Physical Society}

  2. Experimental determination of visibility modeling parameters for aircraft

    NASA Astrophysics Data System (ADS)

    Boettcher, Evelyn J.; Maurer, Tana; Murrill, Steven R.; Miller, Brian

    2010-04-01

    The Federal Aviation Administration (FAA) is presently engaged in research to quantify the visibility of aircraft under two important scenarios: aircraft observed directly by human operators in air traffic control towers (ATCT's), and aircraft observed by human operators through unmanned aerial vehicle (UAV) sensors viewed through ground-based display systems. Previously, an ATCT visibility analysis software tool (FAA Vis) was developed by the U.S. Army Research Laboratory (ARL) in collaboration with the U.S. Army's Night Vision and Electronic Sensors Directorate (NVESD) and the FAA. This tool predicts the probability of detection, recognition, and identification of various aircraft by human observers as a function of range and ATCT height. More recently, a baseline version of a UAV See-And- Avoid visibility analysis software tool was also developed by ARL, again in collaboration with NVESD and the FAA. Important to the calibration of these tools is the empirical determination of target discrimination difficulty criteria. Consequently, a set of human perception experiments were designed and conducted to empirically determine the target recognition and identification discrimination difficulty criteria for a representative set of aircraft. This paper will report on the results and analyses of those experiments.

  3. Determination of dynamic fracture toughness using a new experimental technique

    NASA Astrophysics Data System (ADS)

    Cady, Carl M.; Liu, Cheng; Lovato, Manuel L.

    2015-09-01

    In other studies dynamic fracture toughness has been measured using Charpy impact and modified Hopkinson Bar techniques. In this paper results will be shown for the measurement of fracture toughness using a new test geometry. The crack propagation velocities range from ˜0.15 mm/s to 2.5 m/s. Digital image correlation (DIC) will be the technique used to measure both the strain and the crack growth rates. The boundary of the crack is determined using the correlation coefficient generated during image analysis and with interframe timing the crack growth rate and crack opening can be determined. A comparison of static and dynamic loading experiments will be made for brittle polymeric materials. The analysis technique presented by Sammis et al. [1] is a semi-empirical solution, however, additional Linear Elastic Fracture Mechanics analysis of the strain fields generated as part of the DIC analysis allow for the more commonly used method resembling the crack tip opening displacement (CTOD) experiment. It should be noted that this technique was developed because limited amounts of material were available and crack growth rates were to fast for a standard CTOD method.

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

    DOE PAGESBeta

    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

  5. 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%.

  6. 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.

  7. Experimental determination of circumferential properties of fresh carotid artery plaques.

    PubMed

    Lawlor, Michael G; O'Donnell, Michael R; O'Connell, Barry M; Walsh, Michael T

    2011-06-01

    Carotid endarterectomy (CEA) is currently accepted as the gold standard for interventional revascularisation of diseased arteries belonging to the carotid bifurcation. Despite the proven efficacy of CEA, great interest has been generated in carotid angioplasty and stenting (CAS) as an alternative to open surgical therapy. CAS is less invasive compared with CEA, and has the potential to successfully treat lesions close to the aortic arch or distal internal carotid artery (ICA). Following promising results from two recent trials (CREST; Carotid revascularisation endarterectomy versus stenting trial, and ICSS; International carotid stenting study) it is envisaged that there will be a greater uptake in carotid stenting, especially amongst the group who do not qualify for open surgical repair, thus creating pressure to develop computational models that describe a multitude of plaque models in the carotid arteries and their reaction to the deployment of such interventional devices. Pertinent analyses will require fresh human atherosclerotic plaque material characteristics for different disease types. This study analysed atherosclerotic plaque characteristics from 18 patients tested on site, post-surgical revascularisation through endarterectomy, with 4 tissue samples being excluded from tensile testing based on large width-length ratios. According to their mechanical behaviour, atherosclerotic plaques were separated into 3 grades of stiffness. Individual and group material coefficients were then generated analytically using the Yeoh strain energy function. The ultimate tensile strength (UTS) of each sample was also recorded, showing large variation across the 14 atherosclerotic samples tested. Experimental Green strains at rupture varied from 0.299 to 0.588 and the Cauchy stress observed in the experiments was between 0.131 and 0.779 MPa. It is expected that this data may be used in future design optimisation of next generation interventional medical devices for the

  8. 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.

  9. Experimental determination of the distribution of tail states of hydrogenated amorphous silicon: A transient photocurrent analysis

    SciTech Connect

    Webb, D.P.; Chan, F.Y.M.; Zou, X.C.; Chan, Y.C.; Lam, Y.W.; Lin, S.H.; O'Leary, S.K.; Lim, P.K.

    1997-07-01

    Recent experimental developments have cast doubt on the validity of the common assumption that the distribution of tail states of hydrogenated amorphous silicon exhibits a single exponential functional form. The authors employ transient photocurrent decay measurements to determine this distribution of tail states. In their approach, however, they determine the distribution of tail states directly from the experimental data, without assuming, a priori, a specific functional form. It is found that these experimental results are consistent with other more recent experimental determinations of the distribution of tail states, suggesting the possibility of deviations from a single exponential distribution of tail states in hydrogenated amorphous silicon.

  10. 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

  11. 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…

  12. 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

  13. Depolarising primate experimentation: the good, the bad and the determined.

    PubMed

    Hudson, Michelle

    2009-12-01

    Until I began working at FRAME, I was not really aware of the Three Rs or FRAME's work to promote and progress them. It soon became clear to me that it made scientific sense and that it could make a difference to many thousands of laboratory animals. As an alternatives advocate, I regularly experience optimism, frustration and determination. This is illustrated most clearly by the primate research dilemma. Here, I describe the positive and negative experiences I have had whilst working toward the goal of replacing primate experiments, and how these have led me to undertake a multidisciplinary PhD project on primate use in biomedical research. The aim is to examine how research scientists view the opportunities and challenges involved in the use of primates in biomedical science, and to investigate the feasibility of phasing out their use. As a result of the research, I hope to provide a new perspective, to depolarise the debate and bring about a constructive dialogue between all parties as to how and when primate research could be replaced. PMID:20105018

  14. Non-invasive experimental determination of a CT source model.

    PubMed

    Alikhani, Babak; Büermann, Ludwig

    2016-01-01

    Non-invasive methods to determine equivalent X-ray source models of a CT scanner are presented. A high-precision technique called TRIC ("Time Resolved Integrated Charge") was developed and used to characterize the bow tie filters (BT) of the CT scanner installed at Physikalisch-Technische Bundesanstalt (PTB). Aluminum (Al) and polymethyl methacrylate (PMMA) equivalent thicknesses of the BT filters at all tube high voltages were evaluated, assuming that those consist of only one material. Thereby two different dose probes were used, a solid state detector and an ionization chamber, the former characterized by a significant and the latter by an almost negligible energy dependence of the air kerma response. A method was developed to correct for the energy dependence of the solid state dose probe. Next, a two-component material was assumed and equivalent BT filters were evaluated. The latter method was also applied using the known real BT filter materials and compared with the shape of the real BT filters. Finally, the results obtained by the TRIC method were compared with those obtained by using the so-called COBRA method ("Characterization Of Bow tie Relative Attenuation"), the latter being more suitable for measurements in a clinical environment. PMID:26602858

  15. 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

  16. An experimental procedure to determine heat transfer properties of turbochargers

    NASA Astrophysics Data System (ADS)

    Serrano, J. R.; Olmeda, P.; Páez, A.; Vidal, F.

    2010-03-01

    Heat transfer phenomena in turbochargers have been a subject of investigation due to their importance for the correct determination of compressor real work when modelling. The commonly stated condition of adiabaticity for turbochargers during normal operation of an engine has been revaluated because important deviations from adiabatic behaviour have been stated in many studies in this issue especially when the turbocharger is running at low rotational speeds/loads. The deviations mentioned do not permit us to assess properly the turbine and compressor efficiencies since the pure aerodynamic effects cannot be separated from the non-desired heat transfer due to the presence of both phenomena during turbocharger operation. The correction of the aforesaid facts is necessary to properly feed engine models with reliable information and in this way increase the quality of the results in any modelling process. The present work proposes a thermal characterization methodology successfully applied in a turbocharger for a passenger car which is based on the physics of the turbocharger. Its application helps to understand the thermal behaviour of the turbocharger, and the results obtained constitute vital information for future modelling efforts which involve the use of the information obtained from the proposed methodology. The conductance values obtained from the proposed methodology have been applied to correct a procedure for measuring the mechanical efficiency of the tested turbocharger.

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

    PubMed

    Hathaway, Lucy J; Grandgirard, Denis; Valente, Luca G; Täuber, Martin G; Leib, Stephen L

    2016-03-01

    Streptococcus pneumoniaebacteria 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

  18. 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.

  19. 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. PMID:19345010

  20. A simple, accurate, time-saving and green method for the determination of 15 sulfonamides and metabolites in serum samples by ultra-high performance supercritical fluid chromatography.

    PubMed

    Zhang, Yuan; Zhou, Wei-E; Li, Shao-Hui; Ren, Zhi-Qin; Li, Wei-Qing; Zhou, Yu; Feng, Xue-Song; Wu, Wen-Jie; Zhang, Feng

    2016-02-01

    An analytical method based on ultra-high performance supercritical fluid chromatography (UHPSFC) with photo-diode array detection (PDA) has been developed to quantify 15 sulfonamides and their N4-acetylation metabolites in serum. Under the optimized gradient elution conditions, it took only 7min to separate all 15 sulfonamides and the critical pairs of each parent drug and metabolite were completely separated. Variables affecting the UHPSFC were optimized to get a better separation. The performance of the developed method was evaluated. The UHPSFC method allowed the baseline separation and determination of 15 sulfonamides and metabolites with limit of detection ranging from 0.15 to 0.35μg/mL. Recoveries between 90.1 and 102.2% were obtained with satisfactory precision since relative standard deviations were always below 3%. The proposed method is simple, accurate, time-saving and green, it is applicable to a variety of sulfonamides detection in serum samples. PMID:26780846

  1. Factors that determine the severity of experimental myasthenia gravis.

    PubMed

    Drachman, D B; McIntosh, K R; Yang, B

    1998-05-13

    R antibody production than T cells with specificity for other Torpedo AChR epitopes. This results in production of greater amounts of AChR antibodies, including a critical subset that cross-reacts with autologous mouse AChR. The higher autoantibody levels contribute to the greater susceptibility to EAMG and to the greater severity of manifestations in the B6 strain compared with the bm12 strain. (4) There is a bias in B6 mice toward the production of AChR antibodies of IgG2b isotype. We suggest that T cells specific for alpha 146-162 may contribute to this isotype bias. The IgG2b antibodies appear to have particularly potent "myasthenogenic" effects in rats and mice. (5) Finally, it should be emphasized that these differences in immunological and clinical aspects of EAMG in B6 and bm12 mice are relative rather than absolute. T cells that respond to AChR epitopes other than alpha 146-162 can also provide help for AChR antibody production, albeit less potent. In a sense, this model represents a special case of molecular mimicry. In this case, the source of the foreign antigenic molecule is injection rather than the more usual route of infection. The antigen (Torpedo AChR) is one that these mice would never naturally encounter, and the critical amino acid (lysine 155) of the key epitope (alpha 146-162) is present only in the AChR of electric organs of electric fish and not in the AChR of mice, chickens, cows, or humans. The important point is that a detail of the structure of the foreign antigen--that is, a particular peptide of Torpedo AChR--can determine the severity of an antibody-mediated autoimmune disease, depending on how it interacts with a detail of the structure of the MHC Class II molecule and, in turn, on how the peptide/MHC Class II complex interacts with the available T cell repertoire. (ABSTRACT TRUNCATED) PMID:9668247

  2. A highly accurate interatomic potential for argon

    NASA Astrophysics Data System (ADS)

    Aziz, Ronald A.

    1993-09-01

    A modified potential based on the individually damped model of Douketis, Scoles, Marchetti, Zen, and Thakkar [J. Chem. Phys. 76, 3057 (1982)] is presented which fits, within experimental error, the accurate ultraviolet (UV) vibration-rotation spectrum of argon determined by UV laser absorption spectroscopy by Herman, LaRocque, and Stoicheff [J. Chem. Phys. 89, 4535 (1988)]. Other literature potentials fail to do so. The potential also is shown to predict a large number of other properties and is probably the most accurate characterization of the argon interaction constructed to date.

  3. 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.

  4. An optimized method for the accurate determination of patulin in apple products by isotope dilution-liquid chromatography/mass spectrometry.

    PubMed

    Seo, Miyeong; Kim, Byungjoo; Baek, Song-Yee

    2015-07-01

    Patulin, a mycotoxin produced by several molds in fruits, has been frequently detected in apple products. Therefore, regulatory bodies have established recommended maximum permitted patulin concentrations for each type of apple product. Although several analytical methods have been adopted to determine patulin in food, quality control of patulin analysis is not easy, as reliable certified reference materials (CRMs) are not available. In this study, as a part of a project for developing CRMs for patulin analysis, we developed isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC/MS/MS) as a higher-order reference method for the accurate value-assignment of CRMs. (13)C7-patulin was used as internal standard. Samples were extracted with ethyl acetate to improve recovery. For further sample cleanup with solid-phase extraction (SPE), the HLB SPE cartridge was chosen after comparing with several other types of SPE cartridges. High-performance liquid chromatography was performed on a multimode column for proper retention and separation of highly polar and water-soluble patulin from sample interferences. Sample extracts were analyzed by LC/MS/MS with electrospray ionization in negative ion mode with selected reaction monitoring of patulin and (13)C7-patulin at m/z 153→m/z 109 and m/z 160→m/z 115, respectively. The validity of the method was tested by measuring gravimetrically fortified samples of various apple products. In addition, the repeatability and the reproducibility of the method were tested to evaluate the performance of the method. The method was shown to provide accurate measurements in the 3-40 μg/kg range with a relative expanded uncertainty of around 1%. PMID:25925860

  5. 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. PMID:25058737

  6. Efficient and accurate determination of the overall rotational diffusion tensor of a molecule from 15N relaxation data using computer program ROTDIF

    NASA Astrophysics Data System (ADS)

    Walker, Olivier; Varadan, Ranjani; Fushman, David

    2004-06-01

    We present a computer program ROTDIF for efficient determination of a complete rotational diffusion tensor of a molecule from NMR relaxation data. The derivation of the rotational diffusion tensor in the case of a fully anisotropic model is based on a six-dimensional search, which could be very time consuming, particularly if a grid search in the Euler angle space is involved. Here, we use an efficient Levenberg-Marquardt algorithm combined with Monte Carlo generation of initial guesses. The result is a dramatic, up to 50-fold improvement in the computational efficiency over the previous approaches [Biochemistry 38 (1999) 10225; J. Magn. Reson. 149 (2001) 214]. This method is demonstrated on a computer-generated and real protein systems. We also address the issue of sensitivity of the diffusion tensor determination from 15N relaxation measurements to experimental errors in the relaxation rates and discuss possible artifacts from applying higher-symmetry tensor model and how to recognize them.

  7. 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.

  8. Recent advances in thermal desorption-gas chromatography-mass spectrometery method to eliminate the matrix effect between air and water samples: application to the accurate determination of Henry's law constant.

    PubMed

    Kim, Yong-Hyun; Kim, Ki-Hyun

    2014-05-16

    Accurate values for the Henry's law constants are essential to describe the environmental dynamics of a solute, but substantial errors are recognized in many reported data due to practical difficulties in measuring solubility and/or vapor pressure. Despite such awareness, validation of experimental approaches has scarcely been made. An experimental approach based on thermal desorption-gas chromatography-mass spectrometery (TD-GC-MS) method was developed to concurrently allow the accurate determination of target compounds from the headspace and aqueous samples in closed equilibrated system. The analysis of six aromatics and eight non-aromatic oxygenates was then carried out in a static headspace mode. An estimation of the potential bias and mass balance (i.e., sum of mass measured individually from gas and liquid phases vs. the mass initially added to the system) demonstrates compound-specific phase dependency so that the best results are obtained by aqueous (less soluble aromatics) and headspace analysis (more soluble non-aromatics). Accordingly, we were able to point to the possible sources of biases in previous studies and provide the best estimates for the Henry's constants (Matm(-1)): benzene (0.17), toluene (0.15), p-xylene (0.13), m-xylene (0.13), o-xylene (0.19), styrene (0.27); propionaldehyde (9.26), butyraldehyde (6.19), isovaleraldehyde (2.14), n-valeraldehyde (3.98), methyl ethyl ketone (10.5), methyl isobutyl ketone (3.93), n-butyl acetate (2.41), and isobutyl alcohol (22.2). PMID:24704185

  9. Development of a robust RNA-based classifier to accurately determine ER, PR, and HER2 status in breast cancer clinical samples.

    PubMed

    Wilson, Timothy R; Xiao, Yuanyuan; Spoerke, Jill M; Fridlyand, Jane; Koeppen, Hartmut; Fuentes, Eloisa; Huw, Ling Y; Abbas, Ilma; Gower, Arjan; Schleifman, Erica B; Desai, Rupal; Fu, Ling; Sumiyoshi, Teiko; O'Shaughnessy, Joyce A; Hampton, Garret M; Lackner, Mark R

    2014-11-01

    Breast cancers are categorized into three subtypes based on protein expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2/ERBB2). Patients enroll onto experimental clinical trials based on ER, PR, and HER2 status and, as receptor status is prognostic and defines treatment regimens, central receptor confirmation is critical for interpreting results from these trials. Patients enrolling onto experimental clinical trials in the metastatic setting often have limited available archival tissue that might better be used for comprehensive molecular profiling rather than slide-intensive reconfirmation of receptor status. We developed a Random Forests-based algorithm using a training set of 158 samples with centrally confirmed IHC status, and subsequently validated this algorithm on multiple test sets with known, locally determined IHC status. We observed a strong correlation between target mRNA expression and IHC assays for HER2 and ER, achieving an overall accuracy of 97 and 96%, respectively. For determining PR status, which had the highest discordance between central and local IHC, incorporation of expression of co-regulated genes in a multivariate approach added predictive value, outperforming the single, target gene approach by a 10% margin in overall accuracy. Our results suggest that multiplexed qRT-PCR profiling of ESR1, PGR, and ERBB2 mRNA, along with several other subtype associated genes, can effectively confirm breast cancer subtype, thereby conserving tumor sections and enabling additional biomarker data to be obtained from patients enrolled onto experimental clinical trials. PMID:25338319

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

    PubMed

    Pyo, Jae Sung

    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 (R (2) = 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

  11. 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.

  12. 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

  13. 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

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

    PubMed

    Parkin, John D; Hähner, Georg

    2016-01-01

    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

  15. 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.

  16. 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.

  17. Determination of nitrogen in coal macerals using electron microprobe technique-experimental procedure

    USGS Publications Warehouse

    Mastalerz, Maria; Gurba, L.W.

    2001-01-01

    This paper discusses nitrogen determination with the Cameca SX50 electron microprobe using PCO as an analyzing crystal. A set of conditions using differing accelerating voltages, beam currents, beam sizes, and counting times were tested to determine parameters that would give the most reliable nitrogen determination. The results suggest that, for the instrumentation used, 10 kV, current 20 nA, and a counting time of 20 s provides the most reliable nitrogen determination, with a much lower detection limit than the typical concentration of this element in coal. The study demonstrates that the electron microprobe technique can be used to determine the nitrogen content of coal macerals successfully and accurately. ?? 2001 Elsevier Science B.V. All rights reserved.

  18. Experimental Determination of Paschen Curve and First Townsend Coefficient of Nitrogen Plasma Discharge

    NASA Astrophysics Data System (ADS)

    Wais, Sabah

    2011-10-01

    In the present work, an experimental study is performed to determine the first Townsend coefficient and Paschen curve for N2 gas chamber using a parallel plate geometrical configuration. Paschen curve coefficients are derived by exponential fitting of first Townsend coefficients data of plasma discharge. The experimental data is acquired at different working pressure and various electrode gap separations. Furthermore, the amplification process of the gas gain in non-uniform electric field is realized.

  19. Experimental and analytical determination of vibration characteristics of corrugated, flexibly supported, heat-shield panels

    NASA Technical Reports Server (NTRS)

    Carden, H. D.

    1974-01-01

    Experimental and analytical natural frequencies, nodal patterns, and typical modal displacements for a corrugated, flexibly supported, heat-shield panel are discussed. Good correlation was found between the experimental data and NASTRAN analytical results for the corrugated panel over a relatively wide frequency spectrum covered in the investigation. Of the two experimental techniques used for mode shape and displacement measurements (a noncontacting displacement sensor system and a holographic technique using a helium-neon, continuous-wave laser), the holographic technique was found, in the present investigation, to be faster and better suited for determining a large number of complex nodal patterns of the corrugated panel.

  20. 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.

  1. Experimental determination of self-similarity constant for converging cylindrical shocks

    NASA Astrophysics Data System (ADS)

    Kjellander, Malte; Tillmark, Nils; Apazidis, Nicholas

    2011-11-01

    Guderley's self-similarity solution r = r0(1 - t/t0)α for strong converging cylindrical shocks is investigated experimentally for three different gases with adiabatic exponents γ = 1.13; 1.40; and 1.66 and various values of the initial Mach number. Corresponding values of the similarity exponent α which determines the strength of shock convergence are obtained for each gas thus giving the variation of α with γ. Schlieren imaging with multiple exposure technique is used to track the propagation of a single shock front during convergence. The present experimental results are compared with previous experimental, numerical, and theoretical investigations.

  2. 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.

  3. 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.

  4. An experimental approach to determine the heat transfer coefficient in directional solidification furnaces

    NASA Technical Reports Server (NTRS)

    Banan, Mohsen; Gray, Ross T.; Wilcox, William R.

    1992-01-01

    The heat transfer coefficient between a molten charge and its surroundings in a Bridgman furnace was experimentally determined using in-situ temperature measurement. The ampoule containing an isothermal melt was suddenly moved from a higher temperature zone to a lower temperature zone. The temperature-time history was used in a lumped-capacity cooling model to evaluate the heat transfer coefficient between the charge and the furnace. The experimentally determined heat transfer coefficient was of the same order of magnitude as the theoretical value estimated by standard heat transfer calculations.

  5. Determination of the structure of {gamma}-alumina from interatomic potential and first-principles calculations: The requirement of significant numbers of nonspinel positions to achieve an accurate structural model

    SciTech Connect

    Paglia, Gianluca; Rohl, Andrew L.; Gale, Julian D.; Buckley, Craig E.

    2005-06-01

    We have performed an extensive computational study of {gamma}-Al{sub 2}O{sub 3}, beginning with the geometric analysis of approximately 1.47 billion spinel-based structural candidates, followed by derivative method energy minimization calculations of approximately 122 000 structures. Optimization of the spinel-based structural models demonstrated that structures exhibiting nonspinel site occupancy after simulation were more energetically favorable, as suggested in other computational studies. More importantly, none of the spinel structures exhibited simulated diffraction patterns that were characteristic of {gamma}-Al{sub 2}O{sub 3}. This suggests that cations of {gamma}-Al{sub 2}O{sub 3} are not exclusively held in spinel positions, that the spinel model of {gamma}-Al{sub 2}O{sub 3} does not accurately reflect its structure, and that a representative structure cannot be achieved from molecular modeling when the spinel representation is used as the starting structure. The latter two of these three findings are extremely important when trying to accurately model the structure. A second set of starting models were generated with a large number of cations occupying c symmetry positions, based on the findings from recent experiments. Optimization of the new c symmetry-based structural models resulted in simulated diffraction patterns that were characteristic of {gamma}-Al{sub 2}O{sub 3}. The modeling, conducted using supercells, yields a more accurate and complete determination of the defect structure of {gamma}-Al{sub 2}O{sub 3} than can be achieved with current experimental techniques. The results show that on average over 40% of the cations in the structure occupy nonspinel positions, and approximately two-thirds of these occupy c symmetry positions. The structures exhibit variable occupancy in the site positions that follow local symmetry exclusion rules. This variation was predominantly represented by a migration of cations away from a symmetry positions to other

  6. Determination of the structure of γ -alumina from interatomic potential and first-principles calculations: The requirement of significant numbers of nonspinel positions to achieve an accurate structural model

    NASA Astrophysics Data System (ADS)

    Paglia, Gianluca; Rohl, Andrew L.; Buckley, Craig E.; Gale, Julian D.

    2005-06-01

    We have performed an extensive computational study of γ-Al2O3 , beginning with the geometric analysis of approximately 1.47 billion spinel-based structural candidates, followed by derivative method energy minimization calculations of approximately 122 000 structures. Optimization of the spinel-based structural models demonstrated that structures exhibiting nonspinel site occupancy after simulation were more energetically favorable, as suggested in other computational studies. More importantly, none of the spinel structures exhibited simulated diffraction patterns that were characteristic of γ-Al2O3 . This suggests that cations of γ-Al2O3 are not exclusively held in spinel positions, that the spinel model of γ-Al2O3 does not accurately reflect its structure, and that a representative structure cannot be achieved from molecular modeling when the spinel representation is used as the starting structure. The latter two of these three findings are extremely important when trying to accurately model the structure. A second set of starting models were generated with a large number of cations occupying c symmetry positions, based on the findings from recent experiments. Optimization of the new c symmetry-based structural models resulted in simulated diffraction patterns that were characteristic of γ-Al2O3 . The modeling, conducted using supercells, yields a more accurate and complete determination of the defect structure of γ-Al2O3 than can be achieved with current experimental techniques. The results show that on average over 40% of the cations in the structure occupy nonspinel positions, and approximately two-thirds of these occupy c symmetry positions. The structures exhibit variable occupancy in the site positions that follow local symmetry exclusion rules. This variation was predominantly represented by a migration of cations away from a symmetry positions to other tetrahedral site positions during optimization which were found not to affect the diffraction

  7. 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.

  8. 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.

  9. 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…

  10. Calculation and experimental determination of the fast neutron sensitivity of OSL detectors with hydrogen containing radiators

    NASA Astrophysics Data System (ADS)

    Fellinger, Jürgen; Henniger, Jürgen; Hübner, Klaus

    1984-11-01

    Detectors based on optically stimulated luminescence are useful for fast neutron dosimetry. For this one needs the neutron sensitivity of these detectors. We describe a procedure for the calculation of the neutron sensitivity. For CaF 2:Mn embedded in polyethylene the calculated values are compared with experimentally determined neutron sensitivities. There is good agreement.

  11. Experimental determination of systems suitable for study as monotectic binary metallic alloy solidification models

    NASA Technical Reports Server (NTRS)

    Smith, J. E., Jr.

    1985-01-01

    Transparent binary metallic alloy solidification models are important in attempts to understand the processes causing liquid-liquid and solid-liquid phase transformations in metallic alloy systems. These models permit visual observation of the phase transformation and the processes proceding solidification. The number of these transparent monotectic binary models needs to be expanded to distinguish between the unique and general phenomena observed. The expansion of the number of accurately determined monotectic phase diagrams of model systems, and contribution to a data base for eventual use with UNIFAC group contribution methods is examined.

  12. Density-Dependent Demographic Variation Determines Extinction Rate of Experimental Populations

    PubMed Central

    2005-01-01

    Understanding population extinctions is a chief goal of ecological theory. While stochastic theories of population growth are commonly used to forecast extinction, models used for prediction have not been adequately tested with experimental data. In a previously published experiment, variation in available food was experimentally manipulated in 281 laboratory populations of Daphnia magna to test hypothesized effects of environmental variation on population persistence. Here, half of those data were used to select and fit a stochastic model of population growth to predict extinctions of populations in the other half. When density-dependent demographic stochasticity was detected and incorporated in simple stochastic models, rates of population extinction were accurately predicted or only slightly biased. However, when density-dependent demographic stochasticity was not accounted for, as is usual when forecasting extinction of threatened and endangered species, predicted extinction rates were severely biased. Thus, an experimental demonstration shows that reliable estimates of extinction risk may be obtained for populations in variable environments if high-quality data are available for model selection and if density-dependent demographic stochasticity is accounted for. These results suggest that further consideration of density-dependent demographic stochasticity is required if predicted extinction rates are to be relied upon for conservation planning. PMID:15934788

  13. 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). PMID:16099170

  14. Comparison of experimentally determined and mathematically predicted percutaneous penetration rates of chemicals.

    PubMed

    Korinth, Gintautas; Schaller, Karl Heinz; Bader, Michael; Bartsch, Rüdiger; Göen, Thomas; Rossbach, Bernd; Drexler, Hans

    2012-03-01

    The aim of the study was to evaluate the predictive potential of three different mathematical models for the percutaneous penetration of industrial solvents with respect to our experimental data. Percutaneous penetration rates (fluxes) from diffusion cell experiments of 11 chemicals were compared with fluxes predicted by mathematical models. The chemicals considered were three glycol ethers (2-butoxyethanol, diethylene glycol monobutyl ether and 1-ethoxy-2-propanol), three alcohols (ethanol, isopropanol and methanol), two glycols (ethylene glycol and 1,2-propanediol), one aromatic hydrocarbon (toluene) and two aromatic amines (aniline and o-toluidine). For the mathematical prediction of fluxes, models described by Fiserova-Bergerova et al. (Am J Ind Med 17:617-635 1990), Guy and Potts (Am J Ind Med 23:711-719 1993) and Wilschut et al. (Chemosphere 30:1275-1296 1995) were used. The molecular weights, octanol-water partition coefficients (LogP) and water solubilities of the compounds were obtained from a database for modelling. The fit between the mathematically predicted and experimentally determined fluxes was poor (R(2) = 0.04-0.29; linear regression). The flux differences ranged up to a factor of 412. For 4 compounds, the Guy and Potts model showed a closer fit with the experimental flux than the other models. The Wilschut et al. model showed a lower flux difference for 4 compounds as compared to experimental data than the models of Fiserova-Bergerova et al. and Guy and Potts. The Fiserova-Bergerova et al. model showed for 3 compounds a lower flux difference to experimental data than the other models. This study demonstrates large differences between mathematically predicted and experimentally determined fluxes. The percutaneous penetration as determined in diffusion cell experiments may be considerably overestimated as well as underestimated by mathematical models. Although the number of compounds in our comparison study is small, the results point out that none

  15. Magnifying endoscopy with narrow-band imaging is more accurate for determination of horizontal extent of early gastric cancers than chromoendoscopy

    PubMed Central

    Asada-Hirayama, Itsuko; Kodashima, Shinya; Sakaguchi, Yoshiki; Ono, Satoshi; Niimi, Keiko; Mochizuki, Satoshi; Tsuji, Yosuke; Minatsuki, Chihiro; Shichijo, Satoki; Matsuzaka, Keisuke; Ushiku, Tetsuo; Fukayama, Masashi; Yamamichi, Nobutake; Fujishiro, Mitsuhiro; Koike, Kazuhiko

    2016-01-01

    Background and study aims: Although magnifying endoscopy with narrow-band imaging (ME-NBI) is reported to be useful for delineating the horizontal extent of early gastric cancers (EGCs), there are few reports which have objectively demonstrated the superiority of ME-NBI over chromoendoscopy with indigo carmine for this purpose. We conducted an exploratory comparison of the diagnostic accuracy of both modalities for the delineation of EGCs using prospectively collected data, and clarified the clinicopathological features related to inaccurate evaluation of the horizontal extent of EGCs. Patients and methods: EGCs were assigned to the oral narrow-band imaging (O-NBI) group or the oral chromoendoscopy (O-CE) group before endoscopic submucosal dissection (ESD). The oral border was observed according to assignment, and the anal border with the other modality. The horizontal extent of the tumor was evaluated by each modality and a marking dot was placed on the visible delineation line. After ESD, the marking dots were identified pathologically and defined as “accurate evaluation” if they were located within 1 mm of the pathological tumor border. We compared the rate of accurate evaluation of ME-NBI and chromoendoscopy, and analyzed the clinicopathological features related to inaccurate evaluation. Results: A total of 113 marking dots evaluated by ME-NBI and 116 evaluated by chromoendoscopy were analyzed. The rate of accurate evaluation by ME-NBI was significantly higher than that by chromoendoscopy (89.4 % vs 75.9 %, P = 0.0071). The EGCs with flat borders and large EGCs were significantly related to inaccurate evaluation using ME-NBI. There were no significant factors related to inaccurate evaluation with chromoendoscopy. Conclusions: The accurate evaluation rate of the horizontal extent of EGCs by ME-NBI is significantly higher than that by chromoendoscopy. Study registration: UMIN000007641 PMID:27556080

  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. 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.

  18. 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

  19. 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

  20. A Study to Test the Feasibility of Determining Whether Classified Want Ads in Daily Newspapers Are an Accurate Reflection of Local Labor Markets and of Significant Use to Employers and Job Seekers. Final Report.

    ERIC Educational Resources Information Center

    Olympus Research Corp., Salt Lake City, UT.

    The report summarizes findings of a detailed study to test the feasibility of determining whether want ads in daily newspapers are (1) an accurate reflection of local labor markets and (2) of significant use to employers and job seekers. The study found that want ads are a limited source of information about local labor markets. They are of some…

  1. 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.

  2. Experimental Procedures for Determining the Invariant Triplet-Phases of X-Ray Reflections.

    NASA Astrophysics Data System (ADS)

    Nicolosi, Joseph Anthony

    The phases of x-ray reflections are retained when three-beams diffract simultaneously (Post, 1977, 1979). The phase information can be extracted from the angular distribution of diffracted intensity about the three beam setting. We have investigated methods of optimizng experimental procedures and have developed instrumentation for resolving the intensity asymmetries associated with n-beam interactions in centrosymmetric crystals. A device, which employs two crystals in a skew-parallel arrangement, was designed and used to produce monochromatic ((DELTA)(lamda)/(lamda) (TURN) 5 x 10('-4)) and highly collimated ((alpha)(,(theta)) (TURN) (alpha)(,(omega)) (LESSTHEQ) 60") incident radiation. A 6000 Watt rotating anode x-ray generator was used with a (300 (mu)m)('2) projected focus. An automated diffractometer, which incorporates "absolute" optical encoders, was used to orient and drive the study crystals with an accuracy of (+OR-) 0.001(DEGREES). These experimental procedures yielded an appreciable improvement in sensitivity over procedures used previously which utilized polychromatic and more divergent incident radiation. The sensitivity of our procedures has been checked using perfect crystals of Germanium and Silicon. The improved techniques were used to determine more than 200 triplet-phases experimentally in mosaic crystals of Lead Molybdate and Sulfamic Acid. The experimental phases agreed in all cases with those calculated from the known atomic coordinates of the compounds. The bases for generalized procedures to be used with crystals having large unit cells are discussed. Methods of applying the phase determining rules and estimating the approximate magnitudes of the n-beam interactions are described. The basis for a generalized experimental data collection procedure not restricted to the Renninger geometry is discussed. Such procedures require the use of automated techniques for calculation of experimental parameters of the samples studied.

  3. Theoretical and experimental determination of L -shell decay rates, line widths, and fluorescence yields in Ge

    NASA Astrophysics Data System (ADS)

    Guerra, M.; Sampaio, J. M.; Madeira, T. I.; Parente, F.; Indelicato, P.; Marques, J. P.; Santos, J. P.; Hoszowska, J.; Dousse, J.-Cl.; Loperetti, L.; Zeeshan, F.; Müller, M.; Unterumsberger, R.; Beckhoff, B.

    2015-08-01

    Fluorescence yields (FYs) for the Ge L shell were determined by a theoretical and two experimental groups within the framework of the International Initiative on X-Ray Fundamental Parameters Collaboration. Calculations were performed using the Dirac-Fock method, including relativistic and QED corrections. The experimental value of the L3FY ωL 3 was determined at the Physikalisch-Technische Bundesanstalt undulator beamline of the synchrotron radiation facility BESSY II in Berlin, Germany, and the L α1 ,2 and L β1 line widths were measured at the Swiss Light Source, Paul Scherrer Institute, Switzerland, using monochromatized synchrotron radiation and a von Hamos x-ray crystal spectrometer. The measured fluorescence yields and line widths are compared to the corresponding calculated values.

  4. Experimental determination of carbon dioxide evolution during aerobic composting of agro-wastes.

    PubMed

    Tripathi, Shilpa; Srivastava, J K

    2012-10-01

    This work aims at optimal composting of agro-wastes like sugarcane bagasse, wood straw and soya husk. A mixture of these substances along with small quantity of food waste as the seed was composted aerobically and carbon dioxide evolved was determined experimentally using a composting system comprising aerobic digester, operating in near-optimal conditions with regard to adequacy of oxygen and temperature in the system. During aerobic composting of agro-waste carbon dioxide is produced due to degradation of different carbon fractions in the substrate. Carbon dioxide production rate, which is a measure of bacterial/fungal activity in composting systems, can be related to various process parameters like different carbon fractions present in the substrate and their reaction rates, progress and termination of compost phenomenon and stabilization of organic matter. This gives a balanced compromise between complexity of mathematical model and extensive experimentation, and can be used for determining optimum conditions for composting. PMID:25151714

  5. 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.

  6. On the experimental determination of the one-way speed of light

    NASA Astrophysics Data System (ADS)

    Pérez, Israel

    2011-07-01

    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 close paths. The procedure employed here will provide epistemological tools so that physicists understand that a direct measurement of the speed not only of light but of any physical entity is by no means trivial. Our results shed light on the physics behind the experiments which may be of interest for both physicists with an elemental knowledge in special relativity and philosophers of science.

  7. 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.

  8. An experimental method for directly determining the interconnectivity of melt in a partially molten system

    NASA Technical Reports Server (NTRS)

    Daines, Martha J.; Richter, Frank M.

    1988-01-01

    An experimental method for directly determining the degree of interconnectivity of melt in a partially molten system is discussed using an olivine-basalt system as an example. Samarium 151 is allowed time to diffuse through mixtures of olivine and basalt powder which have texturally equilibrated at 1350 C and 13 to 15 kbars. The final distribution of samarium is determined through examination of developed radiographs of the samples. Results suggest an interconnected melt network is established at melt fractions at least as low as 1 wt pct and all melt is completely interconnected at melt fractions at least as low as 2 wt pct for the system examined.

  9. Theoretical-experimental method of determining the drag coefficient of a harmonically oscillating thin plate

    NASA Astrophysics Data System (ADS)

    Egorov, A. G.; Kamalutdinov, A. M.; Paimushin, V. N.; Firsov, V. A.

    2016-03-01

    A method for determining the drag coefficient of a thin plate harmonically oscillating in a viscous incompressible fluid is proposed. The method is based on measuring the amplitude of deflections of cantilever-fixed thin plates exhibiting damping flexural oscillations with a frequency corresponding to the first mode and on solving an inverse problem of calculating the drag coefficient on the basis of the experimentally found logarithmic decrement of beam oscillations.

  10. Apollo 17 petrology and experimental determination of differentiation sequences in model moon compositions

    NASA Technical Reports Server (NTRS)

    Hodges, F. N.; Kushiro, I.

    1974-01-01

    Experimental studies of model moon compositions are discussed, taking into account questions related to the differentiation of the outer layer of the moon. Phase relations for a series of proposed lunar compositions have been determined and a petrographic and electron microprobe study was conducted on four Apollo 17 samples. Two of the samples consist of high-titanium mare basalts, one includes crushed anorthosite and gabbro, and another contains blue-gray breccia.

  11. Experimental determination of the dynamic tensile strength of liquid Sn, Pb, and Zn

    NASA Astrophysics Data System (ADS)

    Zaretsky, E. B.

    2016-07-01

    An experimental technique capable of determining the dynamic tensile (spall) strength of metals in the liquid state is described. Relying on this technique, spall data on samples of tin, lead, and zinc pre-heated to 20 K above their melting points were obtained. It is found that the spall strength of the metals is low, 40-100 MPa, but not zero and is, seemingly, affected by material purity and by the rate of tensile deformation preceding sample spallation.

  12. 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.

  13. Determination of hydroxy acids in cosmetics by chemometric experimental design and cyclodextrin-modified capillary electrophoresis.

    PubMed

    Liu, Pei-Yu; Lin, Yi-Hui; Feng, Chia Hsien; Chen, Yen-Ling

    2012-10-01

    A CD-modified CE method was established for quantitative determination of seven hydroxy acids in cosmetic products. This method involved chemometric experimental design aspects, including fractional factorial design and central composite design. Chemometric experimental design was used to enhance the method's separation capability and to explore the interactions between parameters. Compared to the traditional investigation that uses multiple parameters, the method that used chemometric experimental design was less time-consuming and lower in cost. In this study, the influences of three experimental variables (phosphate concentration, surfactant concentration, and methanol percentage) on the experimental response were investigated by applying a chromatographic resolution statistic function. The optimized conditions were as follows: a running buffer of 150 mM phosphate solution (pH 7) containing 0.5 mM CTAB, 3 mM γ-CD, and 25% methanol; 20 s sample injection at 0.5 psi; a separation voltage of -15 kV; temperature was set at 25°C; and UV detection at 200 nm. The seven hydroxy acids were well separated in less than 10 min. The LOD (S/N = 3) was 625 nM for both salicylic acid and mandelic acid. The correlation coefficient of the regression curve was greater than 0.998. The RSD and relative error values were all less than 9.21%. After optimization and validation, this simple and rapid analysis method was considered to be established and was successfully applied to several commercial cosmetic products. PMID:22996609

  14. Experimental determination of the distributed dynamic coefficients for a hydrodynamic fluid film bearing

    NASA Astrophysics Data System (ADS)

    Gyurko, John Harrison

    Most current rotor bearing analysis utilizes lumped parameter bearing coefficients to model the static and dynamic characteristics of fluid film bearings. By treating the stiffness and damping properties of the fluid film as acting upon the axial centerline of the rotor, these models are limited in their analysis to first order lateral rotor-bearing motion. The development of numerical methods that distribute the dynamic properties of the fluid film around the bearing circumference allow for higher order analysis of the motion between the bearing and rotor. Assessment of the accuracy of the numerical method used to calculate distributed dynamic fluid film bearing coefficients is performed by developing a novel hydrodynamic journal bearing test rig and experimental testing procedure capable of obtaining measured distributed dynamic coefficients over a range of bearing operating conditions. The instrumented bearing test rig is used to measure the dynamic bearing displacement and fluid film pressure responses from application of an externally applied excitation force. Least squares solution to a system of perturbated pressure equations, populated by measured displacement and pressure responses, is used to determine the hydrodynamic stiffness and damping properties for a finite region of the bearing surface. Incremental rotation of pressure sensors embedded in the body of the test bearing allow for measurement of the fluid film circumferential pressure distribution which is used to calculate a set of experimentally determined dynamic bearing coefficients. Distributed bearing coefficients derived from experimental measurements are compared to numerically calculated distributed coefficients as well as to lumped parameter coefficients generated from experimental and numerical methods found in the literature. Overall, the numerically calculated distributed coefficients successfully model both the circumferential distribution and the operating conditions of the experimental

  15. Assessment of mono-shot measurement as a fast and accurate determination of the laser-induced damage threshold in the sub-picosecond regime.

    PubMed

    Sozet, Martin; Neauport, Jérôme; Lavastre, Eric; Roquin, Nadja; Gallais, Laurent; Lamaignère, Laurent

    2016-02-15

    Standard test protocols need several laser shots to assess the laser-induced damage threshold of optics and, consequently, large areas are necessary. Taking into account the dominating intrinsic mechanisms of laser damage in the sub-picosecond regime, a simple, fast, and accurate method, based on correlating the fluence distribution with the damage morphology after only one shot in optics is therein presented. Several materials and components have been tested using this method and compared to the results obtained with the classical 1/1 method. Both lead to the same threshold value with an accuracy in the same order of magnitude. Therefore, this mono-shot testing could be a straightforward protocol to evaluate damage threshold in short pulse regime. PMID:26872193

  16. Experimentally determined density matrices for H( n =3) formed in H sup + -He collisions from 20 to 100 keV

    SciTech Connect

    Ashburn, J.R.; Cline, R.A.; van der Burgt, P.J.M.; Westerveld, W.B.; Risley, J.S. )

    1990-03-01

    Density matrices describing H({ital n}=3) atoms produced in collisions of 20- to 100-keV protons with He atoms have been determined experimentally. In the experiment the intensity and polarization of Balmer-{alpha} radiation emitted from a He gas cell are measured as a function of the strength of an externally applied electric field. Electric fields are applied in a direction either axial to or transverse to the proton beam. Density matrices are extracted by detailed analysis of the optical data. Data are obtained for each field direction and then analyzed, separately and in combination, to yield density matrices. Satisfactory agreement is found between density matrices determined from axial and transverse electric field data except at the lowest energies studied. Some nonzero density-matrix elements are determined more accurately using axial electric fields than with transverse fields, while other elements are more accurately determined using transverse electric fields. The combined analysis using data from both field directions gives a better determination of the density matrix than the separate data sets. Results for the H({ital n}=3) electron-transfer cross sections (relative to 3{ital s}), the electric dipole moment of the charge distribution {l angle}{bold d}{r angle}{sub {ital z}}, a first-order moment of the current distribution {l angle}{bold L}{times}{bold A}{r angle}{sub {ital z},{ital s}}, and the average coherence Tr({sigma}{sub 3}{sup 2}) are obtained. The experimental results are compared to two recent calculations using the augmented atomic orbital (AO+) theory and the continuum distorted-wave approximation with post-collision interaction theory, and to one recent experimental measurement of the diagonal density-matrix elements. Both theories show qualitative agreement with the general trends in the data. The AO+ method gives better quantitative agreement.

  17. 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.

  18. Experimental determination of the density matrix describing collisionally produced H(n = 3) atoms

    SciTech Connect

    Havener, C.C.; Rouze, N.; Westerveld, W.B.; Risley, A.J.S.

    1986-01-01

    An experimental technique and analysis procedure is described for determining the axially symmetric density matrix for collisionally produced H(n = 3) atoms by measuring the Stokes parameters which characterize the emitted Balmer- radiation as a function of axial and transverse electric fields applied in the collision cell. The electric fields induce strong characteristic variations in the Stokes parameters. The 14 independent elements of the density matrix are determined by fitting the observed Stokes parameters with signals calculated from a theoretical analysis of the experiment. The physical interpretation of the density matrix is presented in terms of graphs of the electron probability distribution and the electron current distribution. Examples of the determination of the density matrix are given for 40-, 60-, and 80-keV H +He electron-transfer collisions.

  19. The accurate determination of bismuth in lead concentrates and other non-ferrous materials by AAS after separation and preconcentration of the bismuth with mercaptoacetic acid.

    PubMed

    Howell, D J; Dohnt, B R

    1982-05-01

    A method for determining 0.0001% and upwards of bismuth in lead, zinc or copper concentrates, metals or alloys and other smelter residues is described. Bismuth is separated from lead, iron and gangue materials with mercaptoacetic acid after reduction of the iron with hydrazine. Large quantities of tin can be removed during the dissolution. An additional separation is made for materials high in copper and/or sulphate. The separated and concentrated bismuth is determined by atomic-absorption spectrometry using the Bi line at 223.1 nm. The proposed method also allows the simultaneous separation and determination of silver. PMID:18963145

  20. 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.

  1. 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.

  2. On the Equivalency of Experimental B(E2) Values Determined by Various Methods

    NASA Astrophysics Data System (ADS)

    Pritychenko, Boris; Birch, Michael; Singh, Balraj; Brookhaven National Laboratory Team; McMaster University Team

    2015-10-01

    Over the last 60 years a variety of experimental methods have been employed to determine reduced transition probabilities in even-even nuclei. Different methods and data analysis techniques imply a strong need for consistency checks of the reported results. To investigate the equivalence of different measurements we have used a recently-developed B(E2) ↑ database. For the first time transition probabilities for Doppler Shift Attenuation (DSA), Recoil Distance Doppler Shift (RDDS), Delayed Coincidences (DC), Nuclear Resonance Fluorescence (NRF) and Coulomb Excitation (CE) methods have been analyzed and compared in the Z = 6-94 region. The analysis of B(E2;01+ -->21+) values of the 100 frequently-studied even-even nuclei indicates these experimental methods produce equivalent results. Possible differences between the DSA and CE values near closed neutron and proton shells could be explained by the experimental deficiencies. Further comparisons of the present data with the inelastic electron scattering (EE') results also show agreement. These findings confirm equivalence of the major experimental methods for a wide range of nuclei. This work was funded by the Office of Nuclear Physics, Office of Science of the U.S. Department of Energy, under Contract No. DE-AC02-98CH10886 with Brookhaven Science Associates, LC.

  3. 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.

  4. Theoretical and experimental determination of steering mechanism for Risley prism systems.

    PubMed

    Lu, Yafei; Zhou, Yuan; Hei, Mo; Fan, Dapeng

    2013-03-01

    Two different analytical methods, the first-order paraxial approximation method and the nonparaxial ray tracing method, are applied to determine the steering mechanism of the Risley prism system, including the pointing prediction and the complete and exact inverse orientation solutions. The analytical results obtained with the two different methods are investigated in detail about the pointing prediction and the two groups of inverse orientation solutions, respectively. Risley prism equipment for wide angular range beam scanning is assembled and the experimental setup is built to test the steering mechanism of the Risley prism system. Experimental results validate the availability of the nonparaxial ray tracing method to discuss the beam steering mechanism for the Risley prism system. PMID:23458790

  5. Experimental phase determination of the structure factor from Kossel line profile

    PubMed Central

    Faigel, G.; Bortel, G.; Tegze, M.

    2016-01-01

    Kossel lines are formed when radiation from point x-ray sources inside a single crystal are diffracted by the crystal itself. In principle, Kossel line patterns contain full information on the crystalline structure: phase and magnitude of the structure factors. The phase is coded into the profile of the lines. Although this was known for a long time, experimental realization has not been presented. In this work we demonstrate experimentally that phases can be directly determined from the profile of the Kossel lines. These measurements are interesting not only theoretically, but they would facilitate structure solution of samples within extreme conditions, such as high pressure, high and low temperatures, high magnetic fields and extremely short times. The parallel measurement of many diffraction lines on a stationary sample will allow a more efficient use of the new generation of x-ray sources the X-ray free electron lasers (XFELs). PMID:26965321

  6. Experimental phase determination of the structure factor from Kossel line profile.

    PubMed

    Faigel, G; Bortel, G; Tegze, M

    2016-01-01

    Kossel lines are formed when radiation from point x-ray sources inside a single crystal are diffracted by the crystal itself. In principle, Kossel line patterns contain full information on the crystalline structure: phase and magnitude of the structure factors. The phase is coded into the profile of the lines. Although this was known for a long time, experimental realization has not been presented. In this work we demonstrate experimentally that phases can be directly determined from the profile of the Kossel lines. These measurements are interesting not only theoretically, but they would facilitate structure solution of samples within extreme conditions, such as high pressure, high and low temperatures, high magnetic fields and extremely short times. The parallel measurement of many diffraction lines on a stationary sample will allow a more efficient use of the new generation of x-ray sources the X-ray free electron lasers (XFELs). PMID:26965321

  7. Experimentally determining the exchange parameters of quasi-two dimensional Heisenbert magnets

    SciTech Connect

    Singleton, John; Sengupta, P; Mcdonald, R D; Cox, S; Harrison, N; Goddard, P A; Lancaster, T; Blundell, S J; Pratt, F L; Manson, J L; Southerland, H I; Schlueter, J A

    2008-01-01

    Though long-range magnetic order cannot occur at temperatures T > 0 in a perfect two-dimensional (2D) Heisenberg magnet, real quasi-2D materials will invariably possess nonzero inter-plane coupling J{sub {perpendicular}} driving the system to order at elevated temperatures. This process can be studied using quantum Monte Carlo calculations. However, it is difficult to test the results of these calculations experimentally since for highly anisotropic materials in which the in-plane coupling is comparable with attainable magnetic fields J{sub {perpendicular}} is necessarily very small and inaccessible directly. In addition, because of the large anisotropy, the Neel temperatures are low and difficult to determine from thermodynamic measurements. Here, we present an elegant method of assessing the calculations via two independent experimental probes: pulsed-field magnetization in fields of up to 85 T, and muon-spin rotation.

  8. 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.

  9. 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. PMID:26086681

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

    PubMed

    Lárraga-Gutiérrez, José Manuel

    2015-08-01

    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. PMID:26161448

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

    PubMed

    González-Salgado, D; Valencia, J L; Troncoso, J; Carballo, E; Peleteiro, J; Romaní, L; Bessières, D

    2007-05-01

    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. PMID:17552856

  12. 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.

  13. Experimental Determination of the Dominant Type of Auger Recombination in InGaN Quantum Wells

    NASA Astrophysics Data System (ADS)

    Galler, Bastian; Lugauer, Hans-Jürgen; Binder, Michael; Hollweck, Richard; Folwill, Yannick; Nirschl, Anna; Gomez-Iglesias, Alvaro; Hahn, Berthold; Wagner, Joachim; Sabathil, Matthias

    2013-11-01

    We investigate theoretically the influence of type and density of background carriers in the active region on the quantum efficiency of InGaN-based light emitters using an extension of the ABC rate model. A method to determine experimentally whether a certain type of Auger recombination is relevant in InGaN quantum wells is derived from these considerations. Using this approach, we show that the physical process which is the dominant cause for the efficiency droop is superlinear in the electron density and can thus be assigned to nnp-Auger recombination.

  14. Experimental Determination of High-Order Bending Elastic Constants of Lipid Bilayers.

    PubMed

    Toscano-Flores, Liliana G; Jacinto-Méndez, Damián; Carbajal-Tinoco, Mauricio D

    2016-06-30

    We present a method to describe the formation of small lipid vesicles in terms of three bending elastic constants that can be experimentally measured. Our method combines a general expression of the elastic free energy of the bilayer and the thermodynamic description of molecular aggregation. The resulting model requires the size distribution of liposomes, which is determined from the X-ray scattered intensity spectra of vesicular dispersions. By using two different preparation methods, we studied a series of vesicular solutions made of distinct lipids and we obtained their corresponding bending elastic constants that are consistent with known bending rigidities. PMID:27267752

  15. Determination of Absorption Coefficient of a Solution by a Simple Experimental Setup

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Deepak; Akhildev, C.; Sreenivasan, P. V.; Leelamma, K. K.; Joseph, Lyjo K.; Anila, E. I.

    2011-10-01

    The absorption coefficients of aqueous potassium permanganate (KMnO4) solution at 638.8 nm for various concentrations are determined using a simple experimental set up. The setup consists of He-Ne laser source (Red, 638.8 nm, 10 mW), a glass jar in which the KMnO4 sample is taken, a mirror strip inclined at 45° to direct the laser beam towards the bottom of the glass jar, a traveling microscope to adjust the position of light dependent resistor (LDR) and a digital multimeter to measure the resistance.

  16. State-of-the-art in permeability determination from well log data: Part 2- verifiable, accurate permeability predictions, the touch-stone of all models

    SciTech Connect

    Mohaghegh, S.; Balan, B.; Ameri, S.

    1995-12-31

    The ultimate test for any technique that bears the claim of permeability prediction from well log data, is accurate and verifiable prediction of permeability for wells from which only the well log data is available. So far all the available models and techniques have been tried on data that includes both well logs and the corresponding permeability values. This approach at best is nothing more than linear or nonlinear curve fitting. The objective of this paper is to test the capability of the most promising of these techniques in independent (where corresponding permeability values are not available or have not been used in development of the model) prediction of permeability in a heterogeneous formation. These techniques are {open_quotes}Multiple Regression{close_quotes} and {open_quotes}Virtual Measurements using Artificial Neural Networks.{close_quotes} For the purposes of this study several wells from a heterogeneous formation in West Virginia were selected. Well log data and corresponding permeability values for these wells were available. The techniques were applied to the remaining data and a permeability model for the field was developed. The model was then applied to the well that was separated from the rest of the data earlier and the results were compared. This approach will test the generalization power of each technique. The result will show that although Multiple Regression provides acceptable results for wells that were used during model development, (good curve fitting,) it lacks a consistent generalization capability, meaning that it does not perform as well with data it has not been exposed to (the data from well that has been put aside). On the other hand, Virtual Measurement technique provides a steady generalization power. This technique is able to perform the permeability prediction task even for the entire wells with no prior exposure to their permeability profile.

  17. 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

    2016-08-01

    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. PMID:27497575

  18. Combining DSMC Simulations and ROSINA/COPS Data of Comet 67P/Churyumov-Gerasimenko to Develop a Realistic Empirical Coma Model and to Determine Accurate Production Rates

    NASA Astrophysics Data System (ADS)

    Hansen, K. C.; Fougere, N.; Bieler, A. M.; Altwegg, K.; Combi, M. R.; Gombosi, T. I.; Huang, Z.; Rubin, M.; Tenishev, V.; Toth, G.; Tzou, C. Y.

    2015-12-01

    We have previously published results from the AMPS DSMC (Adaptive Mesh Particle Simulator Direct Simulation Monte Carlo) model and its characterization of the neutral coma of comet 67P/Churyumov-Gerasimenko through detailed comparison with data collected by the ROSINA/COPS (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/COmet Pressure Sensor) instrument aboard the Rosetta spacecraft [Bieler, 2015]. Results from these DSMC models have been used to create an empirical model of the near comet coma (<200 km) of comet 67P. The empirical model characterizes the neutral coma in a comet centered, sun fixed reference frame as a function of heliocentric distance, radial distance from the comet, local time and declination. The model is a significant improvement over more simple empirical models, such as the Haser model. While the DSMC results are a more accurate representation of the coma at any given time, the advantage of a mean state, empirical model is the ease and speed of use. One use of such an empirical model is in the calculation of a total cometary coma production rate from the ROSINA/COPS data. The COPS data are in situ measurements of gas density and velocity along the ROSETTA spacecraft track. Converting the measured neutral density into a production rate requires knowledge of the neutral gas distribution in the coma. Our empirical model provides this information and therefore allows us to correct for the spacecraft location to calculate a production rate as a function of heliocentric distance. We will present the full empirical model as well as the calculated neutral production rate for the period of August 2014 - August 2015 (perihelion).

  19. 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.

  20. 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.

  1. 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

    2013-08-01

    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. PMID:23848436

  2. 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. PMID:24525301

  3. Experimental determination of the radial temperature profile in a non-neutral plasma

    NASA Astrophysics Data System (ADS)

    Hart, Grant W.

    2005-10-01

    In 1992 Eggleston, et al.^1 reported on a technique for measuring the radial temperature profile in a pure electron plasma by partially dumping the plasma onto a charge collector. Several of their assumptions do not apply to our plasma, and so last year^2 we reported on a modified method which uses a form of equilibrium calculation to determine the temperature. We applied the method to the results of a simulation and found that it gave the correct temperature distribution, but we had no experimental data to apply the method to. We have now applied it to real data and found that the method was extremely sensitive to experimental noise. We have modified the method to make it less sensitive to noise and compared it to the standard `evaporation' method. These experimental results will be presented. ^1D.L.Eggleston, C.F. Driscoll, B.R. Beck, A.W. Hyatt and J.H. Malmberg, Phys. Fluids B 4, 3432 (1992).^2Grant W. Hart and Bryan G. Peterson, Bull. Am. Phys. Soc. 49, 320.

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

    PubMed Central

    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. PMID:26727467

  5. 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. PMID:23086130

  6. Structural determinants of resveratrol for cell proliferation inhibition potency: experimental and docking studies of new analogs.

    PubMed

    Mazué, Frédéric; Colin, Didier; Gobbo, Jessica; Wegner, Maria; Rescifina, Antonio; Spatafora, Carmela; Fasseur, Dominique; Delmas, Dominique; Meunier, Philippe; Tringali, Corrado; Latruffe, Norbert

    2010-07-01

    Resveratrol is the subject of intense research because of the abundance of this compound in the human diet and as one of the most valuable natural chemopreventive agents. Further advances require new resveratrol analogs be used to identify the structural determinants of resveratrol for the inhibition potency of cell proliferation by comparing experimental and docking studies. Therefore, we synthesized new trans/(E)- and cis/(Z)-resveratrol - analogs not reported to date - by modifying the hydroxylation pattern of resveratrol and a double bond geometry. We included them in a larger panel of 14 molecules, including (Z)-3,5,4'-trimethoxystilbene, the most powerful molecule that is used as reference. Using a docking model complementary to experimental studies on the proliferation inhibition of the human colorectal tumor SW480 cell line, we show that methylation is the determinant substitution in inhibition efficacy, but only in molecules bearing a Z configuration. Most of the synthetic methylated derivatives (E or Z) stop mitosis at the M phase and lead to polyploid cells, while (E)-resveratrol inhibits cells at the S phase. Docking studies show that almost all of the docked structures of (Z)-polymethoxy isomers, but not most of the (E)-polymethoxy isomers substantially overlap the docked structure of combretastatin A-4, taken as reference ligand at the colchicine-tubulin binding site. PMID:20395019

  7. Experimental determination of the residual stresses in a Kraft recovery boiler tube

    SciTech Connect

    Wang, Xun-Li; Payzant, E.A.; Taljat, B.

    1997-07-01

    Neutron diffraction was used to determine the residual stresses in a spiral weld overlay tube used in Kraft recovery boilers by the pulp and paper industry. The specimen was a 2.5 inches OD carbon steel tube covered with a layer of Inconel 625 weld overlay. Residual strains in the carbon steel and weld overlay layers were determined using the ferritic (211) and austenitic (311) reflections, respectively. Residual stresses in each material were derived from the measured strains using Hooke`s law and appropriate elastic constants. Tensile stress regions were found not only in the weld metal but also in the heat affected zone in the carbon steel. The maximum tensile stress was located in the weld overlay layer and was found to be 360 MPa, or about 75% of the yield strength of the weld metal. The experimental data were compared with a finite element analysis based on an uncoupled thermal-mechanical formulation. Overall, the modeling results were in satisfactory agreement with the experimental data, although the hoop strain (stress) appears to have been overestimated by the finite element model. Additional neutron diffraction measurements on an annealed tube confirmed that these welding residual stresses were eliminated after annealing at 900{degrees}C for 20 minutes. 18 refs., 7 figs.

  8. Computational knee ligament modeling using experimentally determined zero-load lengths.

    PubMed

    Bloemker, Katherine H; Guess, Trent M; Maletsky, Lorin; Dodd, Kevin

    2012-01-01

    This study presents a subject-specific method of determining the zero-load lengths of the cruciate and collateral ligaments in computational knee modeling. Three cadaver knees were tested in a dynamic knee simulator. The cadaver knees also underwent manual envelope of motion testing to find their passive range of motion in order to determine the zero-load lengths for each ligament bundle. Computational multibody knee models were created for each knee and model kinematics were compared to experimental kinematics for a simulated walk cycle. One-dimensional non-linear spring damper elements were used to represent cruciate and collateral ligament bundles in the knee models. This study found that knee kinematics were highly sensitive to altering of the zero-load length. The results also suggest optimal methods for defining each of the ligament bundle zero-load lengths, regardless of the subject. These results verify the importance of the zero-load length when modeling the knee joint and verify that manual envelope of motion measurements can be used to determine the passive range of motion of the knee joint. It is also believed that the method described here for determining zero-load length can be used for in vitro or in vivo subject-specific computational models. PMID:22523522

  9. Computational Knee Ligament Modeling Using Experimentally Determined Zero-Load Lengths

    PubMed Central

    Bloemker, Katherine H; Guess, Trent M; Maletsky, Lorin; Dodd, Kevin

    2012-01-01

    This study presents a subject-specific method of determining the zero-load lengths of the cruciate and collateral ligaments in computational knee modeling. Three cadaver knees were tested in a dynamic knee simulator. The cadaver knees also underwent manual envelope of motion testing to find their passive range of motion in order to determine the zero-load lengths for each ligament bundle. Computational multibody knee models were created for each knee and model kinematics were compared to experimental kinematics for a simulated walk cycle. One-dimensional non-linear spring damper elements were used to represent cruciate and collateral ligament bundles in the knee models. This study found that knee kinematics were highly sensitive to altering of the zero-load length. The results also suggest optimal methods for defining each of the ligament bundle zero-load lengths, regardless of the subject. These results verify the importance of the zero-load length when modeling the knee joint and verify that manual envelope of motion measurements can be used to determine the passive range of motion of the knee joint. It is also believed that the method described here for determining zero-load length can be used for in vitro or in vivo subject-specific computational models. PMID:22523522

  10. 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.

  11. Experimental determination of the light-trapping-induced absorption enhancement factor in DSSC photoanodes

    PubMed Central

    Falconieri, Mauro

    2015-01-01

    Summary For dye-sensitized solar cells (DSSC), the fundamental process that determines the maximum short-circuit current is the absorption of light. In such devices, this is produced by the concurrent phenomena of light absorption by dye molecules and light trapping in the mesoporous, titania photoanode structure. The decoupling of these two phenomena is important for device characterization and the design of novel photoelectrode geometries with increased optical performance. In this paper, this task is addressed by introducing a spectral absorption enhancement factor as a parameter to quantify the light trapping effect. The experimental value of this parameter was obtained by comparing the experimentally determined fraction of absorbed light by a dye-sensitized photoanode with the light absorbed by the dye without the mesoporous titania structure. In order to gain more insight from this result, the fraction of light absorbed in the photoanode (on the basis of the dye loading capacity of the titania nanospheres) was also calculated by an optical model for the two extreme cases of the absence of light trapping and maximum light trapping. Accordingly, the photocurrent was calculated under the assumption of solar irradiation, which defined two useful boundaries. Using the experimentally derived values of the spectral absorption enhancement factor in the photoanode optical model, the DSSC short-circuit current can be calculated with good agreement with the value measured in practical devices based on the same photoanode structures. Therefore, our approach provides a realistic description of a practical device and can be exploited as an useful tool to assess the optical functionality of novel photoanode structures. PMID:25977859

  12. 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

  13. Feasibility of ultra-high performance liquid and gas chromatography coupled to mass spectrometry for accurate determination of primary and secondary phthalate metabolites in urine samples.

    PubMed

    Herrero, Laura; Calvarro, Sagrario; Fernández, Mario A; Quintanilla-López, Jesús Eduardo; González, María José; Gómara, Belén

    2015-01-01

    Phthalates (PAEs) are ubiquitous toxic chemical compounds. During the last few years, some phthalate metabolites (MPAEs) have been proposed as appropriate biomarkers in human urine samples to determine PAE human intake and exposure. So, it is necessary to have fast, easy, robust and validated analytical methods to determine selected MPAEs in urine human samples. Two different instrumental methods based on gas (GC) and ultra-high performance liquid (UHPLC) chromatography coupled to mass spectrometry (MS) have been optimized, characterized and validated for the simultaneous determination of nine primary and secondary phthalate metabolites in urine samples. Both instrumental methods have similar sensitivity (detection limits ranged from 0.03 to 8.89 pg μL(-1) and from 0.06 to 0.49 pg μL(-1) in GC-MS and UHPLC-MS(2), respectively), precision (repeatability, expressed as relative standard deviation, which was lower than 8.4% in both systems, except for 5OH-MEHP in the case of GC-MS) and accuracy. But some advantages of the UHPLC-MS(2) method, such as more selectivity and lower time in the chromatographic runs (6.8 min vs. 28.5 min), have caused the UHPLC-MS(2) method to be chosen to analyze the twenty one human urine samples from the general Spanish population. Regarding these samples, MEP showed the highest median concentration (68.6 μg L(-1)), followed by MiBP (23.3 μg L(-1)), 5cx-MEPP (22.5 μg L(-1)) and MBP (19.3μgL(-1)). MMP (6.99 μg L(-1)), 5oxo-MEHP (6.15 μg L(-1)), 5OH-MEHP (5.30 μg L(-1)) and MEHP (4.40 μg L(-1)) showed intermediate levels. Finally, the lowest levels were found for MBzP (2.55 μg L(-1)). These data are within the same order of magnitude as those found in other similar populations. PMID:25467512

  14. Can Contemporary Density Functional Theory Predict Energy Spans in Molecular Catalysis Accurately Enough To Be Applicable for in Silico Catalyst Design? A Computational/Experimental Case Study for the Ruthenium-Catalyzed Hydrogenation of Olefins.

    PubMed

    Rohmann, Kai; Hölscher, Markus; Leitner, Walter

    2016-01-13

    The catalytic hydrogenation of cyclohexene and 1-methylcyclohexene is investigated experimentally and by means of density functional theory (DFT) computations using novel ruthenium Xantphos(Ph) (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) and Xantphos(Cy) (4,5-bis(dicyclohexylphosphino)-9,9-dimethylxanthene) precatalysts [Ru(Xantphos(Ph))(PhCO2)(Cl)] (1) and [Ru(Xantphos(Cy))(PhCO2)(Cl)] (2), the synthesis, characterization, and crystal structures of which are reported. The intention of this work is to (i) understand the reaction mechanisms on the microscopic level and (ii) compare experimentally observed activation barriers with computed barriers. The Gibbs free activation energy ΔG(⧧) was obtained experimentally with precatalyst 1 from Eyring plots for the hydrogenation of cyclohexene (ΔG(⧧) = 17.2 ± 1.0 kcal/mol) and 1-methylcyclohexene (ΔG(⧧) = 18.8 ± 2.4 kcal/mol), while the Gibbs free activation energy ΔG(⧧) for the hydrogenation of cyclohexene with precatalyst 2 was determined to be 21.1 ± 2.3 kcal/mol. Plausible activation pathways and catalytic cycles were computed in the gas phase (M06-L/def2-SVP). A variety of popular density functionals (ωB97X-D, LC-ωPBE, CAM-B3LYP, B3LYP, B97-D3BJ, B3LYP-D3, BP86-D3, PBE0-D3, M06-L, MN12-L) were used to reoptimize the turnover determining states in the solvent phase (DF/def2-TZVP; IEF-PCM and/or SMD) to investigate how well the experimentally obtained activation barriers can be reproduced by the calculations. The density functionals B97-D3BJ, MN12-L, M06-L, B3LYP-D3, and CAM-B3LYP reproduce the experimentally observed activation barriers for both olefins very well with very small (0.1 kcal/mol) to moderate (3.0 kcal/mol) mean deviations from the experimental values indicating for the field of hydrogenation catalysis most of these functionals to be useful for in silico catalyst design prior to experimental work. PMID:26713773

  15. A new third-level charge pumping method for accurate determination of interface-trap parameters in metal-oxide-semiconductor field-effect-transistors

    NASA Astrophysics Data System (ADS)

    Autran, Jean-Luc; Balland, Bernard

    1994-06-01

    We propose a new implementation of the third-level charge pumping technique for a precise determination of the energy distributions of electron and hole cross sections and interface state density in metal-oxide-semiconductor field-effect transistors (MOSFETs). Using an arbitrary function generator with a high clock rate and a sufficient storage memory length, it is possible to evaluate interface trap emission times and interface state densities in small geometry MOSFETs with a high-enegy resolution. The accuracy of the technique has been greatly increased owing to the high stability and the weak distortion of the signal applied to the gate of the device (numerically generating via a high-speed digital-to-analog converter) and the development of a new acquisition procedure. To illustrate the performance of this method, we present the first results concerning the characterization of 0.6 μm N-channel MOSFETs.

  16. 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

  17. An in vivo experimental model to determine antigenic variations among infectious bursal disease viruses.

    PubMed

    Durairaj, Vijay; Linnemann, Erich; Icard, Alan H; Williams, Susan M; Sellers, Holly S; Mundt, Egbert

    2013-08-01

    Infectious bursal disease virus (IBDV) is a double-stranded RNA virus causing infectious bursal disease in chickens. IBDV undergoes antigenic drift, so characterizing the antigenicity of IBDV plays an important role for identification and selection of vaccine candidates. In this study, an in vivo experimental model was developed to differentiate a new antigenic variant of IBDV. To this end, a hyper-immune serum to IBDV E/Del-type virus was generated in specific pathogen-free chickens and a standard volume of the hyper-immune serum was serially diluted and injected in specific pathogen-free birds via intravenous, subcutaneous, or intramuscular routes. The chickens were bled at different time points in order to evaluate the dynamics of virus neutralization titres. Based on the results, chickens were injected with different serum dilutions by the subcutaneous route. Twenty-four hours later, chickens were bled and then challenged with 100 median chicken infectious doses of the E/Del virus and a new IBDV variant. Chickens were euthanized at 7 days post infection and the bursa of Fabricius was removed for microscopic evaluation to determine the bursal lesion score. The determined virus neutralization titre along with the bursal lesion score was used to determine the breakthrough titre in the in vivo chicken model. Based on the data obtained, an antigenic subtype of IBDV was identified and determined to be different from E/Del. This model is a sensitive model for determination of IBDV antigenicity of non-tissue culture adapted IBDV. PMID:23662946

  18. Experimental determination of the Boltzmann constant: An undergraduate laboratory exercise for molecular physics or physical chemistry

    NASA Astrophysics Data System (ADS)

    Campbell, H. M.; Boardman, B. M.; DeVore, T. C.; Havey, D. K.

    2012-12-01

    This article describes an undergraduate laboratory exercise that uses optical spectroscopy to determine the magnitude and the uncertainty of the Boltzmann constant kb. The more accurate approach uses photoacoustic spectroscopy to measure the Doppler-broadened line profile of individual spectral lines of N2O to extract kb. Measurements and estimates of the uncertainties in the quantities needed to calculate kb from the line profiles are then used to estimate the uncertainty in kb. This experiment is unusual in that it uses advanced laser-based spectroscopy techniques to emphasize standard practices of uncertainty analysis. The core instrumentation is modular and relatively affordable; it requires a tunable single-mode laser, photoreceiver, optical cell, and vacuum pump. If this instrumentation is not available, an alternate approach can be performed which uses the intensity of each rotational transition of an infrared band to measure kb. Although there is more uncertainty using the alternate approach, low concentrations of CO2, DCl, or N2O give reasonable results for the magnitude of kb. Student assessment results indicate retention and mastery of the concept of combined measurement uncertainty.

  19. An Experimental Study in Determining Energy Expenditure from Treadmill Walking using Hip-Worn Inertial Sensors

    PubMed Central

    Vathsangam, Harshvardhan; Emken, Adar; Schroeder, E. Todd; Spruijt-Metz, Donna; Sukhatme, Gaurav S.

    2011-01-01

    This paper describes an experimental study in estimating energy expenditure from treadmill walking using a single hip-mounted triaxial inertial sensor comprised of a triaxial accelerometer and a triaxial gyroscope. Typical physical activity characterization using accelerometer generated counts suffers from two drawbacks - imprecison (due to proprietary counts) and incompleteness (due to incomplete movement description). We address these problems in the context of steady state walking by directly estimating energy expenditure with data from a hip-mounted inertial sensor. We represent the cyclic nature of walking with a Fourier transform of sensor streams and show how one can map this representation to energy expenditure (as measured by V O2 consumption, mL/min) using three regression techniques - Least Squares Regression (LSR), Bayesian Linear Regression (BLR) and Gaussian Process Regression (GPR). We perform a comparative analysis of the accuracy of sensor streams in predicting energy expenditure (measured by RMS prediction accuracy). Triaxial information is more accurate than uniaxial information. LSR based approaches are prone to outlier sensitivity and overfitting. Gyroscopic information showed equivalent if not better prediction accuracy as compared to accelerometers. Combining accelerometer and gyroscopic information provided better accuracy than using either sensor alone. We also analyze the best algorithmic approach among linear and nonlinear methods as measured by RMS prediction accuracy and run time. Nonlinear regression methods showed better prediction accuracy but required an order of magnitude of run time. This paper emphasizes the role of probabilistic techniques in conjunction with joint modeling of triaxial accelerations and rotational rates to improve energy expenditure prediction for steady-state treadmill walking. PMID:21690001

  20. 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.

  1. 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 (λem ) of 358 nm after excitation (λex ) 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. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26456088

  2. Evaluation of triple stage mass spectrometry as a robust and accurate diagnostic tool for determination of free cordycepin in designer egg.

    PubMed

    Chen, Yi Hsin; Lim, Chee Wei; Chan, Sheot Harn

    2014-05-01

    Direct determination of free cordycepin in designer egg using a highly selective mass spectrometric (MS) technique aided by a rapid and efficient dilute-and-shoot workflow would enhance their application as diagnostic tools in food fraud control. Here, triple stage mass spectrometry (MS(3)) demonstrated excellent analyte selectivity capability even when incomplete chromatographic separation was performed. Method validation was performed at six concentration levels of 100, 200, 400, 800, 1200 and 1600ngg(-1). Spiking experiments were examined at three concentration levels of 200, 400, and 1200ngg(-1) in individual egg white and egg yolk, measured over 2days. MS(3) enabled ion chromatograms with zero-background interference to be made in egg extracts. MS(3) eliminated severe over recovery (p<0.05) observed in all fortified samples, a challenge that MRM-transition could not address in a single step. Matrix-matched calibrants were needed to compensate for over recovery observed under MRM-transition mode. PMID:24360442

  3. Predictive algorithms for determination of reflectance data from quantity of pigments within experimental dental resin composites

    PubMed Central

    2015-01-01

    Background Being able to estimate (predict) the final spectrum of reflectance of a biomaterial, especially when the final color and appearance are fundamental for their clinical success (as is the case of dental resin composites), could be a very useful tool for the industrial development of these type of materials. The main objective of this study was the development of predictive models which enable the determination of the reflectance spectrum of experimental dental resin composites based on type and quantity of pigments used in their chemical formulation. Methods 49 types of experimental dental resin composites were formulated as a mixture of organic matrix, inorganic filler, photo activator and other components in minor quantities (accelerator, inhibitor, fluorescent agent and 4 types of pigments). Spectral reflectance of all samples were measured, before and after artificial chromatic aging, using a spectroradiometer. A Multiple Nonlinear Regression Model (MNLR) was used to predict the values of the Reflectance Factors values in the visible range (380 nm-780 nm), before and after aging, from % Pigment (%P1, %P2, %P3 and %P4) within the formulation. Results The average value of the prediction error of the model was 3.46% (SD: 1.82) across all wavelengths for samples before aging and 3.54% (SD: 1.17) for samples after aging. The differences found between the predicted and measured values of the chromatic coordinates are smaller than the acceptability threshold and, in some cases, are even below the perceptibility threshold. Conclusions Within the framework of this pilot study, the nonlinear predictive models developed allow the prediction, with a high degree of accuracy, of the reflectance spectrum of the experimental dental resin composites. PMID:26329369

  4. 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. PMID:27164833

  5. 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.

  6. An experimental study for determining human discomfort response to roll vibration

    NASA Technical Reports Server (NTRS)

    Leatherwood, J. D.; Dempsey, T. K.; Clevenson, S. A.

    1976-01-01

    An experimental study using a passenger ride quality apparatus (PRQA) was conducted to determine the subjective reactions of passengers to roll vibrations. The data obtained illustrate the effect upon human comfort of several roll-vibration parameters: namely, roll acceleration level, roll frequency, and seat location (i.e., distance from axis of rotation). Results of an analysis of variance indicated that seat location had no effect on discomfort ratings of roll vibrations. The effect of roll acceleration level was significant, and discomfort ratings increased markedly with increasing roll acceleration level at all roll frequencies investigated. Of particular interest, is the fact that the relationship between discomfort ratings and roll acceleration level was linear in nature. The effect of roll frequency also was significant as was the interaction between roll acceleration level and roll frequency.

  7. 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.

  8. Experimental determination of cloud influence on the spectral UV irradiance and implications for biological effects

    NASA Astrophysics Data System (ADS)

    Mateos, David; di Sarra, Alcide; Meloni, Daniela; di Biagio, Claudia; Sferlazzo, Damiano M.

    2011-08-01

    Measurements of UV spectra, total ozone, cloud cover, and cloud optical thickness, obtained at Lampedusa (central Mediterranean), are used to investigate the influence of clouds on the spectral UV irradiance, through the cloud modification factor (CMF), and on five biological processes. The CMF decreases with cloud optical thickness (COT), from about 0.5 for COT˜15 to 0.25 for COT˜45, and decreases with increasing wavelength above 315-320-nm. Observations display an increase in the CMF from 295 to 320-nm, which is related to enhanced absorption by tropospheric ozone due to the long photon path lengths under cloudy conditions. The use of a wavelength independent CMF instead of the experimentally determined spectral curves produces an overestimation of the biological effects of UV irradiance. The overestimation may be as large as 30% for the DNA damage, 20% for vitamin D synthesis, 12% for plant damage, and 8-10% for phytoplankton inhibition and erythema.

  9. Experimental determination and prediction of the gas-liquid n-hexadecane partition coefficients.

    PubMed

    Mutelet, F; Rogalski, M

    2001-07-20

    Experimental methods based on gas-phase chromatography were tested with a view to determine the gas-liquid n-hexadecane partition coefficients, log L16 of non-volatile compounds at 298.2 K. It was demonstrated that reliable values of log L16 of compounds more volatile than n-docosane can be obtained using either capillary, or packed columns. The main limitation of both methods is the column stability at high temperatures. Here we propose a new method based on the temperature gradient mode, to obtain log L16 of high-boiling compounds. A group contribution model is also presented in view to predicting log L16 values of non-volatile compounds. PMID:11510537

  10. Experimental determination of the transport number of water in Nafion 117 membrane

    SciTech Connect

    Fuller, T.F.; Newman, J. . Dept. of Chemical Engineering)

    1992-05-01

    The transport number of water in Nafion 117 membrane over a wide range of water contents is determined experimentally using a concentration cell. The transport number of water, the ratio f[sup m][sub o]/Z[sub o], is about 1.4 for a membrane equilibrated with saturated water vapor at 25[degrees]C, decreases slowly as the membrane is dehydrated, and falls sharply toward zero as the concentration of water approaches zero. In this paper, the relationship between the transference number, the transport number, and the electro-osmotic drag coefficient is presented, and their relevance to water management is solid-polymer-electrolyte fuel cells is discussed. Results are compared with other data available in the literature and with the theoretical maximum.

  11. 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

  12. Experimental study on the precise orbit determination of the BeiDou navigation satellite system.

    PubMed

    He, Lina; Ge, Maorong; Wang, Jiexian; Wickert, Jens; Schuh, Harald

    2013-01-01

    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

  13. 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.

  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 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.

  16. A rapid and accurate method for the determination of plutonium in food using magnetic sector ICP-MS with an ultra-sonic nebuliser and ion chromatography.

    PubMed

    Evans, P; Elahi, S; Lee, K; Fairman, B

    2003-02-01

    In the event of a nuclear incident it is essential that analytical information on the distribution and level of contamination is available. An ICP-MS method is described which can provide data on plutonium contamination in food within 3 h of sample receipt without compromising detection limits or accuracy relative to traditional counting methods. The method can also provide simultaneous determinations of americium and neptunium. Samples were prepared by HNO3 closed-vessel microwave digestion, evaporated to dryness and diluted into a mobile phase comprising 1.5 M HNO3 and 0.1 mM 2,6-pyridinedicarboxylic acid. A commercially available polystyrene-divinylbenzene ion chromatography column provides on-line separation of 239Pu and 238U reducing the impact of the 238U1H interference. Oxidation of the sample using H2O2 ensures all Pu is in the Pu(+4) state. The oxidation also displaces Np away from the solvent front by changing the oxidation state from Np(+3) to Np(+4) and produces the insoluble Am(+4) ion. Simultaneous Pu, Am and Np analyses therefore require omission of the oxidation stage and some loss of Pu data quality. Analyses were performed using a magnetic sector ICP-MS (Finnigan MAT Element). The sample is introduced to the plasma via an ultrasonic nebuliser-desolvation unit (Cetac USN 6000AT+). This combination achieves an instrumental sensitivity of 238U > 2 x 10(7) cps/ppb and removes hydrogen from the sample gas, which also inhibits the formation of 238U1H. The net effect of the improved sample introduction conditions is to achieve detection levels for Pu of 0.020 pg g(-1) (4.6 x 10(-2) Bq kg(-1)) which is significantly below 1/10th of the most stringent EU (European Union) legislation, currently 0.436 pg g(-1) (1 Bq kg(-1)) set for baby food. The new method was evaluated with a range of biological samples ranging from cabbage to milk and meat. Recovery of Pu agrees with published values (100% +/- 20%). PMID:12619774

  17. Combined use of medium mass resolution and desolvation introduction system for accurate plutonium determination in the femtogram range by inductively coupled plasma-sector-field mass spectrometry

    NASA Astrophysics Data System (ADS)

    Pointurier, Fabien; Pottin, Anne-Claire; Hémet, Philippe; Hubert, Amélie

    2011-03-01

    Formation of a polyatomic species made of an atom of a heavy element like lead, mercury or iridium, and atoms abundant in plasma (argon, nitrogen, oxygen, and hydrogen) when using an inductively coupled plasma-sector-field mass spectrometer (ICP-SFMS) may lead to false detection of femtograms (fg) of plutonium or bias in the measured concentrations. Mathematical corrections, based on the measurement of heavy element concentrations in the sample solutions and determination of the extents of formation of the polyatomic interferences, are efficient but time-consuming and degrade detection limits. We describe and discuss a new method based on the combination of, on the one hand, medium mass resolution (MR) of the ICP-SFMS to separate plutonium isotopes physically from interfering polyatomic species, and, on the other, use of a desolvation introduction system (DIS) to enhance sensitivity, thus partly compensating for the loss of transmission due to use of a higher resolution. Plutonium peaks are perfectly separated from the major interfering species (PbO 2, HgAr, and IrO 3) with a mass resolution of ~ 4000. The resulting nine-fold transmission loss is partly compensated by a five-fold increase in sensitivity obtained with the DIS and a lower background. The instrumental detection limits for plutonium isotopes, calculated for measurements of pure synthetic solutions, of the new method (known as MR-DIS method) and of the one currently used in the laboratory (LR method), based on a low mass resolution equal to 360, a microconcentric nebulizer and two in-line cooled spray chambers, are roughly equivalent, at around 0.2 fg ml - 1 . Regarding the measurement of real-life samples, the results obtained with both methods agree and the corresponding analytical detection limits for plutonium isotopes 239Pu, 240Pu and 241Pu are of a few fg·ml - 1 of sample solution, slightly lower with the MR-DIS method than with the current LR method. Although less sensitive than other plutonium

  18. Novel, Precise, Accurate Ion-Pairing Method to Determine the Related Substances of the Fondaparinux Sodium Drug Substance: Low-Molecular-Weight Heparin.

    PubMed

    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 (r(2)) 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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. Experimental test of a method for determining causal connectivities of species in reactions.

    PubMed

    Torralba, Antonio S; Yu, Kristine; Shen, Peidong; Oefner, Peter J; Ross, John

    2003-02-18

    Theoretical analysis has shown the possibility of determining causal connectivities of reacting species and the reaction mechanism in complex chemical and biochemical reaction systems by applying pulse changes of concentrations of one or more species, of arbitrary magnitude, and measuring the temporal response of as many species as possible. This method, limited to measured and pulsed species, is given here an experimental test on a part of glycolysis including the sequence of reactions from glucose to fructose 1,6-biphosphate, followed by the bifurcation of that sequence into two branches, one ending in glycerol 3-phosphate, the other in glyceraldehyde 3-phosphate. Pulses of concentrations of one species at a time are applied to the open system in a non-equilibrium stationary state, and the temporal responses in concentrations of six metabolites are measured by capillary zone electrophoresis. From the results of these measurements and the use of the theory for their interpretation, we establish the causal connectivities of the metabolites and thus the reaction mechanism, including the bifurcation of one chain of reactions into two. In this test case of the pulse method, no prior knowledge was assumed of the biochemistry of this system. We conclude that the pulse method is relatively simple and effective in determining reaction mechanisms in complex systems, including reactants, products, intermediates, and catalysts and their effectors. The method is likely to be useful for substantially more complex systems. PMID:12576555

  4. 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. PMID:25300180

  5. A review of experimental methods for solid solubility determination in cryogenic systems

    NASA Astrophysics Data System (ADS)

    De Stefani, V.; Baba-Ahmed, A.; Richon, D.

    2004-09-01

    Over the past years, there have been a number of serious explosions in air industry, which have resulted in workers injuries and fatalities. At the same time, there has been an increase in the use of air separation products for industrial activities. The quality of air entering an air separation plant is of crucial importance for its safe and reliable operation and the interest in the solubility data of solids in cryogenic liquid solvents is closely connected to the problem of impurities accumulation in the process plant and storage tanks. Such accumulations, especially in liquid oxygen, may cause fouling and blockage in heat exchangers and pipelines and they may eventually cause serious explosions. For this reason the air contaminants composition in liquid oxygen must be determined with great precision. This paper aims at reviewing experimental methods for determining the solubility of solid compounds that may be present in the cryogenic liquefaction processing of air distillation. A review of the literature data on solubility of solids in liquid oxygen and nitrogen is included as well. Emphasis is given to the difficulties in setting-up measuring apparatuses working at extreme conditions, i.e. low compositions and low temperatures.

  6. 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}.

  7. Simple experimental method for alpha particle range determination in lead iodide films.

    PubMed

    Dmitriev, Yuri; Bennett, Paul R; Cirignano, Leonard J; Klugerman, Mikhail; Shah, Kanai S

    2007-05-01

    An experimental method for determining the range of alpha particles in films based on I-V(s) analysis has been suggested. The range of 5.5 MeV alpha particles in PbI(2) films determined by this technique is 30+/-5 microm, and this value is in agreement with the value calculated by SRIM (the stopping and range of ions in matter), r=24 microm in PbI(2). More than 100 I-V(s) of PbI(2) films with different thicknesses and quality have been analyzed, and the influence of alpha particle radiation on PbI(2) I-V(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(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(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(s). PMID:17552841

  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. Preliminary analysis of problem of determining experimental performance of air-cooled turbine I : methods for determining heat-transfer characteristics

    NASA Technical Reports Server (NTRS)

    Ellerbrock, Herman H , Jr; Ziemer, Robert R

    1950-01-01

    In determining the experimental performance of an air-cooled turbine, the heat-transfer characteristics must be evaluated. The suggested formulas that are required to determine these characteristics are presented. The formulas have a form in which dependent parameters are expressed as unknown functions of independent parameters. Methods of experimenting to determine these functions are suggested. In some cases general heat-transfer discussions that lead to the suggested forms of the formulas are given.

  11. Determination of equivalent breast phantoms for different age groups of Taiwanese women: An experimental approach

    SciTech Connect

    Dong, Shang-Lung; Chu, Tieh-Chi; Lin, Yung-Chien; Lan, Gong-Yau; Yeh, Yu-Hsiu; Chen, Sharon; Chuang, Keh-Shih

    2011-07-15

    Purpose: Polymethylmethacrylate (PMMA) slab is one of the mostly used phantoms for studying breast dosimetry in mammography. The purpose of this study was to evaluate the equivalence between exposure factors acquired from PMMA slabs and patient cases of different age groups of Taiwanese women in mammography. Methods: This study included 3910 craniocaudal screen/film mammograms on Taiwanese women acquired on one mammographic unit. The tube loading, compressed breast thickness (CBT), compression force, tube voltage, and target/filter combination for each mammogram were collected for all patients. The glandularity and the equivalent thickness of PMMA were determined for each breast using the exposure factors of the breast in combination with experimental measurements from breast-tissue-equivalent attenuation slabs. Equivalent thicknesses of PMMA to the breasts of Taiwanese women were then estimated. Results: The average {+-} standard deviation CBT and breast glandularity in this study were 4.2 {+-} 1.0 cm and 54% {+-} 23%, respectively. The average equivalent PMMA thickness was 4.0 {+-} 0.7 cm. PMMA slabs producing equivalent exposure factors as in the breasts of Taiwanese women were determined for the age groups 30-49 yr and 50-69 yr. For the 4-cm PMMA slab, the CBT and glandularity values of the equivalent breast were 4.1 cm and 65%, respectively, for the age group 30-49 yr and 4.4 cm and 44%, respectively, for the age group 50-69 yr. Conclusions: The average thickness of PMMA slabs producing the same exposure factors as observed in a large group of Taiwanese women is less than that reported for American women. The results from this study can provide useful information for determining a suitable thickness of PMMA for mammographic dose survey in Taiwan. The equivalence of PMMA slabs and the breasts of Taiwanese women is provided to allow average glandular dose assessment in clinical practice.

  12. 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.

  13. 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

  14. 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

  15. Experimental determination and characterization of the gap promoter of Bifidobacterium bifidum S17

    PubMed Central

    Sun, Zhongke; Westermann, Christina; Yuan, Jing; Riedel, Christian U

    2014-01-01

    The DNA sequence upstream of the glyceraldehyde 3-phosphate dehydrogenase gene (gap) of various strains of bifidobacteria is used in a number of vector systems for homologous and heterologous expression in this group of bacteria. To date none of the bifidobacterial gap promoters (Pgap) have been verified experimentally. Here, we probe a range of putative bifidobacterial promoters hypothesized to show high constitutive transcriptional activity using a β-glucuronidase reporter system. In silico analysis revealed a predicted bacterial promoter upstream of the gap gene of Bifidobacterium bifidum S17. The corresponding DNA sequences was cloned into the promoter probe vector pMDY23 and yielded highest reporter activities among the promoter sequences tested confirming previous studies. Using rapid amplification of cDNA ends (5′-RACE), we identified the transcription start site (TSS) of Pgap of B. bifidum S17. The experimentally determined TSS and the associated -10 and -35 regions do not match with the promoter predicted in silico. Moreover, a potential ribosome-binding site (RBS) was identified upstream of the ATG start codon of the gap gene, which is complementary to the 3′-end of the 16S rRNA with only 1 mismatch suggesting efficient initiation of translation. Alignment of the Pgap sequences of a number of representative bifidobacteria showed a high level of conservation and the presence of -35 and -10 regions, which are similar but not identical to the consensus promoter sequences of house-keeping genes of Escherichia coli and Bacillus subtilis. Collectively, these results confirm the suitability of Pgap for high level, constitutive expression in bifidobacteria. PMID:25482086

  16. Grading More Accurately

    ERIC Educational Resources Information Center

    Rom, Mark Carl

    2011-01-01

    Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…

  17. 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

  18. Dynamic rupture simulation with an experimentally-determined friction law leads to slip-pulse propagation

    NASA Astrophysics Data System (ADS)

    Liao, Z.; Chang, J. C.; Reches, Z.

    2013-12-01

    We simulate the dynamic rupture along a vertical, strike-slip fault in an elastic half-space. The fault has frictional properties that were determined in high-velocity, rotary shear apparatus Sierra-White granite. The experimental fault was abruptly loaded by a massive flywheel, which is assumed to simulate the loading of a fault patch during an earthquake, and termed Earthquake-Like-Slip Event (ELSE) (Chang et al., 2012). The experiments revealed systematic alteration between slip-weakening and slip-strengthening (Fig. 1A), and were considered as proxies of fault-patch behavior during earthquakes of M = 4-8. We used the friction-distance relations of these experiments to form an empirical slip-dependent friction model, ELSE-model (Fig. 1B). For the dynamic rupture simulation, we used the program of Ampuero (2002) (2D spectral boundary integral elements) designed for anti-plane (mode III) shear fracturing. To compare with published works, the calculations used a crust with mechanical properties and stress state of Version 3 benchmark of SCEC (Harris et al., 2004). The calculations with a fault of ELSE-model friction revealed: (1) Rupture propagation in a slip-pulse style with slip cessation behind the pulse; (2) Systematic decrease of slip distance away from the nucleation zone; and (3) Spontaneous arrest of the dynamic rupture without a barrier. These features suggest a rupture of a self-healing slip-pulse mode (Fig. 1C), in contrast to rupturing of a fault with linear slip-weakening friction (Fig. 1B) (Rojas et al., 2008) in crack-like mode and no spontaneous arrest. We deduce that the slip-pulse in our simulation results from the fast recovery of shear strength as observed in ELSE experiments, and argue that incorporating this experimentally-based friction model to rupture modeling produces realistic propagation style of earthquake rupture. Figure 1 Fault patch behavior during an earthquake. (A) Experimental evolution of frictional stress, slip velocity, and

  19. 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.

  20. Experimentally Determined Vapor Pressures of Carbon Dioxide from 167 to 87 K

    NASA Astrophysics Data System (ADS)

    Nelson, R. N.; Michael, B. P.; Allen, J. E., Jr.

    1999-09-01

    Carbon dioxide (CO{_2}) is a major constituent in the Martian atmosphere and its abundance is controlled by surface condensation primarily at the poles. Because the sublimation temperature is determined by the vapor pressure curve, the saturation law is arguably the most important physical property of CO{_2} for Mars. A number of different representations have been used for the vapor pressure of CO{_2}; however, they are all based on data taken sixty-five years ago (Meyers and Van Dusen 1933) or calculations and extrapolations based on that data (e.g., Brown and Ziegler 1980). Using our apparatus specifically designed for low-temperature measurements of thermodynamic properties, we have experimentally determined the vapor pressure of CO{_2} from 167 to 87 K, corresponding to a pressure range of 100 to 1.8x10{(-6}) Torr and set by our lowest measurable pressure. Our preliminary data have been fitted with a simple Clausius-Clapeyron representation and compared with an extrapolation of the form recommended by Brown and Ziegler (1980). For comparison the extrapolation predicts a pressure of 1.1x10{(-6}) Torr at 87 K, whereas our measured value is 1.8x10{(-6}) Torr at this temperature. Further refinement of the data to account for thermal transpiration and fitting with a more comprehensive three-parameter model are in progress. References: Brown, G. N., Jr. and Ziegler, W. T. 1980. In Advances in Cryogenic Engineering, vol. 25 (K. Timmerhaus and H. A. Snyder, Eds.), pp. 662-670. (New York: Plenum Press). Meyers, C. H. and Van Dusen, M. S. 1933, J. Res. Natl. Bur. Stndrds. 84, 2843. Support from NASA's Planetary Atmospheres Program is gratefully acknowledged.

  1. 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.

  2. Preliminary results of experimental measurements to determine microparticle charge in a complex plasma

    NASA Astrophysics Data System (ADS)

    Gillman, Eric; Amatucci, Bill

    2015-09-01

    Microparticles in a dusty plasma typically collect many of the more mobile electrons as they charge up and therefore typically attain a net negative potential. The charge on these microparticles is typically estimated by calculating the charge on a spherical capacitor at the floating potential or by making measurements of particles levitating in the plasma sheath. However, secondary processes can alter the charging process and are significantly altered in the plasma sheath. Currently there is no reliable method to measure microparticle surface charge in the bulk region of complex or dusty plasmas. A novel, non-invasive, experimental method of measuring the charging of microparticles in the bulk region of a plasma will be presented. Ions impinging directly upon the microparticle surface and interacting electrostatically with the charged microparticle, known as collisional and electrostatic Coulomb ion drag, respectively, slows particle acceleration due to gravity as the particle falls through a plasma discharge. Since ion and neutral drag are commonly the dominant forces on microparticles in complex plasmas, the reduced acceleration is measured without a plasma to determine the neutral drag. By repeating the measurement with a plasma and subtracting the neutral drag, the ion drag is obtained. The microparticle net charge is then ascertained from the ion drag on isolated grains falling through a plasma discharge. This work was supported by the Naval Research Laboratory Base Program.

  3. 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.

  4. An experimental model to determine the level of antibiotics in irradiated tissues

    SciTech Connect

    Cruz, N.I.; Ariyan, S.; Miniter, P.; Andriole, V.T.

    1984-05-01

    An experimental study was designed using male Sprague-Dawley rats treated with a single dose of 1800 rads to an area of skin and soft tissue of the back measuring 2 X 3 cm. This dose was estimated to produce changes equivalent to 6000 rads in divided doses over 6 weeks. At intervals of 5, 10, and 15 weeks after irradiation, punch biopsies were taken from both irradiation, and nonirradiated skin areas of each animal 30 minutes after the intraperitoneal administration of gentamicin. Skin homogenates were prepared, and the antibiotic levels in these samples were determined by a bacterial growth inhibition assay. The antibiotic levels were found to be equal (16.1 +/- 6 micrograms/ml vs. 16.0 +/- 5 micrograms/ml) in both irradiated and nonirradiated skin at 5 weeks after radiation. However, at 10 and 15 weeks after radiation, the antibiotic levels had dropped to 9.9 +/- 3 micrograms/ml in irradiated skin compared with 14.1 +/- 4 micrograms/ml in normal skin (p less than 0.001) and with 5.4 micrograms/ml in irradiated skin vs. 11.8 +/- 5 micrograms/ml in nonirradiated skin (p less than 0.001), respectively. Results demonstrate that in spite of adequate gentamicin levels in the circulation and nonirradiated tissue in rats, gentamicin has a decreasing ability to diffuse into irradiated tissues with increasing intervals after therapeutic doses of radiation.

  5. Numerical and experimental determination of neutron characteristics in irradiation rigs operated in LVR-15 research reactor.

    PubMed

    Koleska, Michal; Viererbl, Ladislav; Lahodova, Zdena; Ernest, Jaroslav; Zmitkova, Jelena; Marek, Milan

    2014-10-01

    The LVR-15 reactor is a 10-MW research reactor mostly dedicated to material research and isotope production. Material testing can be performed in various irradiation loops and rigs. For specimen irradiation, several rig constructions can be used, including standard single-cell CHOUCA rigs or special dedicated multi-cell rigs. The temperature in the rigs is controlled by a temperature control system, which can be operated in a stable or pulsed mode, with regard to the rig design. Irradiation conditions in the rig are monitored by a set of various fluence detectors. From these detectors, neutron fluence and its energy distribution can be determined for the whole volume of irradiation samples. Besides measurement, irradiation conditions are calculated by the Monte Carlo code MCNPX, which provides a complete review of irradiation conditions including neutron fluence and its energy distribution in samples and detectors, radiation damage and radiation heating conditions for the rig. A set of experimental and theoretical characteristics for dedicated irradiation positions in the core reflector and in fuel will be provided. PMID:24972899

  6. Experimental determination of the coefficients of the hydraulic resistance of apertures in the rotary disks

    NASA Astrophysics Data System (ADS)

    Shvets, I. T.; Dyban, Ye. P.; Selyavin, G. F.; Stradomskiy, M. V.

    1988-01-01

    Following are some conclusions reached in the determination of the haydraulic resistance of apertures in rotary disks: (1) rotation of disk exerts a substantial influence on condition of course of air through apertures. In the large ratios of the velocity of the rotation of the mean flow rate in the aperture (order u/c = 2.5) the value of the coefficient of flow rate for the apertures with the sharp entering edges decreases approximately 6 times; (2) with sufficient high u/c (more than 4) effect of form of entering edges it is possible not to consider; (3) rounding of trailing edges virtually does not have effect on conditions of air flow through apertures in rotary disks; (4) coefficient of flow rate of apertures of square form investigated in work is close to coefficient of expenditure of cylindrical channels (with identical hydraulic radii); (5) relative depth of aperture in the range of relations 0.96 less than l/d less than 6.04 virtually does not have effect on dependence of value of coefficient of flow rate from rotation; (6) on the basis of analysis of experimental data in work empirical dependence of coefficients of flow rate and hydraulic resistance on parameters K and K, are obtained. The ratios indicated are valid for the disk, which rotates in the housing with the value relative to the axial clearance between the disk and the housing of more than 1.5.

  7. 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. PMID:26775205

  8. 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.

  9. 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.

  10. 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. PMID:21277186

  11. 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.

  12. The experimental determination of the torsional barrier and shape for disilane.

    PubMed

    Moazzen-Ahmadi, N; Horneman, V-M

    2006-05-21

    The torsional spectrum of disilane was recorded for the first time under high-pressure-pathlength conditions and at a spectral resolution of 0.007 cm(-1) using a Bruker IFS-120 HR Fourier transform spectrometer. The spectrum shows six distinct Q branches. The most prominent Q branch is near 130 cm(-1) which is a blend of four components of the torsional fundamental. Of the remaining five, four were assigned to the first torsional hot band (v(4)=2<--1) and one to the second torsional hot band (v(4)=3<--2). Over 350 transitions were identified. An analysis of the torsional fundamental, the first torsional hot band, and the lower state combination differences from frequencies of the vibrational bands nu(9) and nu(9)+nu(4)-nu(4) was made to characterize the torsion-rotation Hamiltonian in the ground vibrational state. The barrier height, barrier shape, and the rotational constant about the Si-Si bond were determined to be 404.344(83) cm(-1), 2.255(65) cm(-1), and 43208(28) MHz, respectively. Comparison of simulated and the experimental spectra yielded (mu||-mu(perpendicular))/mu(perpendicular)= -4(1) for the torsional dipole moments. This ratio compares well with -3.39(6) for ethane. A comparison of molecular parameters obtained here is made with those for methyl silane and ethane. PMID:16729816

  13. The experimental determination of the torsional barrier and shape for disilane

    NASA Astrophysics Data System (ADS)

    Moazzen-Ahmadi, N.; Horneman, V.-M.

    2006-05-01

    The torsional spectrum of disilane was recorded for the first time under high-pressure-pathlength conditions and at a spectral resolution of 0.007cm-1 using a Bruker IFS-120 HR Fourier transform spectrometer. The spectrum shows six distinct Q branches. The most prominent Q branch is near 130cm-1 which is a blend of four components of the torsional fundamental. Of the remaining five, four were assigned to the first torsional hot band (v4=2←1) and one to the second torsional hot band (v4=3←2). Over 350 transitions were identified. An analysis of the torsional fundamental, the first torsional hot band, and the lower state combination differences from frequencies of the vibrational bands ν9 and ν9+ν4-ν4 was made to characterize the torsion-rotation Hamiltonian in the ground vibrational state. The barrier height, barrier shape, and the rotational constant about the Si-Si bond were determined to be 404.344(83)cm-1, 2.255(65)cm-1, and 43208(28)MHz, respectively. Comparison of simulated and the experimental spectra yielded (μ‖-μ⊥)/μ⊥=-4(1) for the torsional dipole moments. This ratio compares well with -3.39(6) for ethane. A comparison of molecular parameters obtained here is made with those for methyl silane and ethane.

  14. T-Cell Properties Determine Disease Site, Clinical Presentation, and Cellular Pathology of Experimental Autoimmune Encephalomyelitis

    PubMed Central

    Abromson-Leeman, Sara; Bronson, Rod; Luo, Yi; Berman, Michael; Leeman, Rebecca; Leeman, Joshua; Dorf, Martin

    2004-01-01

    Two distinct clinical phenotypes of experimental autoimmune encephalomyelitis are observed in BALB interferon-γ knockout mice immunized with encephalitogenic peptides of myelin basic protein. Conventional disease, characterized by ascending weakness and paralysis, occurs with greater frequency after immunizing with a peptide comprising residues 59 to 76. Axial-rotatory disease, characterized by uncontrolled axial rotation, occurs with greater frequency in mice immunized with a peptide corresponding to exon 2 of the full length 21.5-kd protein. The two clinical phenotypes are histologically distinguishable. Conventional disease is characterized by inflammation and demyelination primarily in spinal cord, whereas axial-rotatory disease involves inflammation and demyelination of lateral medullary areas of brain. Both types have infiltrates in which neutrophils are a predominating component. By isolating T cells and transferring disease to naïve recipients, we show here that the type of disease is determined entirely by the inducing T cell. Furthermore, studies using CXCR2 knockout recipients, unable to recruit neutrophils to inflammatory sites, show that although neutrophils are critical for some of these T cells to effect disease, there are also interferon-γ-deficient T cells that induce disease in the absence of both interferon-γ and neutrophils. These results highlight the multiplicity of T-cell-initiated effector pathways available for inflammation and demyelination. PMID:15509523

  15. Experimental investigation of an inversion technique for the determination of broadband duct mode amplitudes by the use of near-field sensor arrays.

    PubMed

    Castres, Fabrice O; Joseph, Phillip F

    2007-08-01

    This paper is an experimental investigation of an inverse technique for deducing the amplitudes of the modes radiated from a turbofan engine, including schemes for stablizing the solution. The detection of broadband modes generated by a laboratory-scaled fan inlet is performed using a near-field array of microphones arranged in a geodesic geometry. This array geometry is shown to allow a robust and accurate modal inversion. The sound power radiated from the fan inlet and the coherence function between different modal amplitudes are also presented. The knowledge of such modal content is useful in helping to characterize the source mechanisms of fan broadband noise generation, for determining the most appropriate mode distribution model for duct liner predictions, and for making sound power measurements of the radiated sound field. PMID:17672635

  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. 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.

  19. 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.

  20. 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

  1. 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

  2. Experimental Determination of Equilibrium and Non-equilibrium Thermodynamic Propertiesof Natural Porous Media.

    NASA Astrophysics Data System (ADS)

    Peluso, F.; Arienzo, I.

    Experimental investigation of the behavior of porous media is a field of interest of modern non-equilibrium thermodynamics. In the frame of a multi-disciplinary re- search project we are performing in our laboratory experimental tests to measure equilibrium and nonequilibrium thermodynamic properties of natural porous media. Aim of our study is to characterize some stone samples and to verify whether a mass transport due to coupled pressure and temperature gradients (thermo-mechanic) is ap- preciable in this kind of porous medium. We have designed an apparatus that allows to measure the volume flux across a porous sample at various, predefined pressures and temperatures, both in isothermal and non isothermal conditions. A mechanical piston compels a liquid to flow through the sample, previously saturated under vacuum with the same fluid. Knowing the geometrical dimensions of the stone, the volume flux is estimated by measuring the time needed to a known amount of liquid to flow across the sample. Measurements have been performed in isothermal conditions at various temperatures and in non-isothermal conditions. Non-isothermal measurements have been performed both in unsteady and steady-state thermal conditions. Before to be undergone to a measurement cycle, samples are dried and weighted. Then they are sat- urated under vacuum with pure distilled water and weighted once again. By difference between the two measurements, porosity is determined. In all examined samples the volume flux has been found linear with respect to the applied pressure at the various temperatures. The values of volume flux in unsteady thermal conditions are consid- erably higher than the one obtained at the same pressure in isothermal conditions at the higher temperature (T=+45rC). This could be the evidence of a thermo-mechanic effect, pushing the water from hot to cold. Once the steady thermal state is reached, however, this effect disappears. Only measurements performed in unsteady thermal

  3. 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

  4. Experimental Determination of the Partitioning Behavior of Noble Gases Between Carbonate and Silicate Liquids

    NASA Astrophysics Data System (ADS)

    Burnard, P.; Koga, K. T.

    2010-12-01

    Carbonatitic melts have been identified in the earth’s upper mantle and experimental evidence suggests that such melts are stable at mantle conditions. Due to high carbonatite/silicate partition coefficients for certain trace elements, and due to the low melting points, low viscosities and low dihedral angles of carbonatite liquids, these liquids play a significant role in trace element fractionation in the mantle. However, the solubilities of the noble gases in carbonatitic liquids are poorly constrained although initial data at low pressure (1 bar) surprisingly suggest that the noble gases are poorly soluble in carbonatite liquids [1]. Partitioning of noble gases relative to the parents of radiogenic noble gases - primarily U, Th and K - has consequences for the isotopic evolution of mantle noble gases, consequently determination of noble gas solubilities in carbonatite phases is of extreme interest for mantle geodynamics. Two-liquid experimental charges consisting of nephelenite and Na2CO3 were synthesized at 1145 C and pressures between 0.6 and 2.5 GPa in sealed Au-Pd capsules in a piston cylinder apparatus. The experimental runs were c. 12h in duration and the charges were quenched at >200 C min-1 to form two immiscibly separated glasses phases. The nephelenite glass starting material had been saturated with a noble gas mixture (0.5 He, 0.02 Ne, 0.48 Ar) prior to synthesis. This procedure introduced noble gases without creating a free gas phase. The noble gases (He and Ar only) were measured in 3 stages: 1) the capsule was pierced under vacuum and the ‘free gas’ residing in the capsule pore space was analysed; 2) the entire capsule was heated to 250 C and the gases liberated were analysed and 3) the nephelenite glass was melting by a CO2 laser and the gases liberated analysed. The first stage of the analysis was to measure any noble gases (principally He) that may have diffused out of the carbonatite during the quench or between the period (of a few

  5. Experimental determination of the surface photometric contribution in the spectral reflectance deconvolution processes for a simulated martian crater-like regolithic target

    NASA Astrophysics Data System (ADS)

    Cord, Aurélien M.; Pinet, Patrick C.; Daydou, Yves; Chevrel, Serge D.

    2005-05-01

    We produce bidirectional reflectance experimental measurements in the visible and near-infrared range of a macroscopic target simulating the case of a martian crater. Using Hapke's equation of radiative transfer, we compare the performance, in terms of mineralogical abundance determination, of different deconvolution processes on a multispectral image of the experimental target. In particular, we study the effects of the topography and the physical properties of natural rocky surfaces (e.g., local variations of incidence and emergence angles, grain size variations, mixtures of materials) on the data interpretation. For this purpose, we increase progressively the amount of quantitative knowledge available in terms of Hapke parameters description, textural properties and topography for the target. We estimate the accuracy of results in comparison with the known ground truth as a function of the level of knowledge we have of the target and carry out a critical assessment on the relative applicability of the different processes. This study shows that the more important parameters to take into account are (in decreasing order): (1) the textural roughness which is shown essential for the accurate determination of mineralogical abundances; (2) the disparity of Hapke parameters across the target (3) the topography (DEM) that has a limited influence on the results. These findings have obvious implications for interpreting planetary regolith reflectance properties in terms of photometry, spectroscopy and mineralogy, measured either from spaceborne (e.g., Io observations from Galileo, Mars from Mars-Express/HRSC and OMEGA) or in situ (Mars Pathfinder, MER) instruments.

  6. Experimental determination of carbon isotope fractionation between CaCO 3 and graphite

    NASA Astrophysics Data System (ADS)

    Deines, Peter; Eggler, David H.

    2009-12-01

    Carbon isotopic exchange between graphite and three polymorphs of CaCO 3 was investigated at temperatures of 600-1400 °C and at pressures from 1.4 to 2.3 GPa. Fractionation factors at all temperatures were determined by the partial exchange treatment of Northrop and Clayton (1966). Graphite starting material for the majority of the experiments was milled in water for 20-25 h, producing aggregates of nanosheets. The sheets range in width from 50 to 1000 nm and in thickness from 20 to 30 nm, and they retain hexagonal symmetry. Isotopic exchange appears to be the sum of surface exchange and interior exchange. At 1100-1400 °C, interior exchange exceeded surface exchange, probably by a combination of grain growth, as determined by increase in crystallite size, recrystallization, as observed in FESEM images, and diffusion. In some runs at 1200 and 1400 °C with an isotopic contrast between the initial graphite and calcite of close to 50‰, equilibrium fractionation was actually overstepped due to a kinetic effect. A weighted regression of fractionation factors from the high-temperature runs yields the line of equilibrium interior exchange: 1000lnα=3.28(0.07)×106/T2. Our calibration lies between the empirical geothermometers of Kitchen and Valley (1995) and Valley and O'Neil (1981) and, accordingly, with a substantial body of data from granulite-facies metamorphic rocks. At 600-700 °C surface exchange greatly exceeded interior exchange, with a much lower activation energy. Interior exchange was slight to nonexistent because there was no crystal growth, no recrystallization, and, probably, little diffusion. Fractionation factors are ˜1‰ higher than the interior exchange factors. Surface exchange probably occurred in the outer one or two unit cells of nanosheets. In previous experimental studies, similar surface-dominated fractionations apparently were measured, even at high temperatures. At 750-1000 °C, exchange rates and fractionation factors followed the low

  7. 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

  8. Experimental evaluation of fatty acid profiles as a technique to determine dietary composition in benthic elasmobranchs.

    PubMed

    Beckmann, Crystal L; Mitchell, James G; Seuront, Laurent; Stone, David A J; Huveneers, Charlie

    2013-01-01

    Fatty acid (FA) analysis is a tool for dietary investigation that complements traditional stomach content analyses. Controlled feeding experiments were used to determine the extent to which the FA composition of diet is reflected in the liver and muscle tissue of the Port Jackson shark Heterodontus portusjacksoni. Over 10 wk, two groups of sharks were fed prawns or squid, which have distinct FA profiles. The percentage of total FA was significantly different for shark liver and muscle tissue when comparing controls with prawn- and squid-fed sharks. Compared with experimentally fed sharks, control shark muscle and liver had higher levels of 18:1n-9 and 20:2n-9. When comparing prawn- and squid-fed sharks, only liver tissue showed a significant difference in FA profiles. The livers of prawn-fed sharks were comparatively higher in 18:1n-7, 22:5n-3, 20:0, and 18:1n-9, while the squid-fed sharks had higher levels of 16:0 and 22:6n-3. These FAs in shark liver tissue were all reflective of higher amounts in their respective dietary items, demonstrating the conservative transfer of FA from diet to liver tissue. This study shows that liver and muscle FA profiles can be used as indicators of dietary change through the comparison of controls and fed sharks. The timescale of this study may not have been sufficient for capturing the integration of FA into muscle tissue because only liver FA profiles were useful to distinguish between sharks fed different diets. These findings have important implications for sampling design where FA profiles are used to infer dietary preferences. PMID:23434786

  9. Experimental determination of the Si isotope fractionation factor between liquid metal and liquid silicate

    NASA Astrophysics Data System (ADS)

    Hin, Remco C.; Fitoussi, Caroline; Schmidt, Max W.; Bourdon, Bernard

    2014-02-01

    The conditions of core formation and the abundances of the light elements in Earth's core remain debated. Silicon isotope fractionation provides a tool contributing to this subject. We present experimentally determined Si isotope fractionation factors between liquid metal and liquid silicate at 1450 °C and 1750 °C, which allow calibrating the temperature dependence of Si isotope fractionation. Experiments were performed in a centrifuging piston cylinder at 1 GPa, employing both graphite and MgO capsules. Tin was used to lower the melting temperature of the metal alloys for experiments performed at 1450 °C. Tests reveal that neither Sn nor C significantly affects Si isotope fractionation. An alkaline fusion technique was employed to dissolve silicate as well as metal phases prior to ion exchange chemistry and mass spectrometric analysis. The results show that metal is consistently enriched in light isotopes relative to the silicate, yielding average metal-silicate fractionation factors of -1.48±0.08‰ and -1.11±0.14‰ at 1450 °C and 1750 °C, respectively. The temperature dependence of equilibrium Si isotope fractionation between metal and silicate can thus be described as Δ30SiMetal-Silicate=-4.42(±0.05)×106/T2. The Si isotope equilibrium fractionation is thus about 1.7 times smaller than previously proposed on the basis of experiments. A consequence of this smaller fractionation is that the calculated difference between the Si isotope composition of the bulk Earth and that of the bulk silicate Earth generated by core formation is smaller than previously thought. It is therefore increasingly difficult to match the Si isotope composition of the bulk silicate Earth with that of chondrites for metal-silicate equilibration temperatures above ∼2500 K. This suggests that Si isotopes were more sensitive to the early stages of core formation when low oxygen fugacities allowed significant incorporation of Si into metal.

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

    SciTech Connect

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

    2006-04-15

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

  11. 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.

  12. Determination of Selected B-complex Vitamins in the NIST Multivitamin Reference Standard Material by Stable Isotope Dilution Mass Spectrometry (Experimental Biology, April, 2007, Washington, D.C.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is increased interest in accurately assessing the total dietary intake of vitamins from all sources, including foods and dietary supplements. Isotope dilution can be a definitive analytical method for very accurate concentration determinations. Thus, a liquid chromatographic (LC) isotope dilut...

  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. Accurate measurement of time

    NASA Astrophysics Data System (ADS)

    Itano, Wayne M.; Ramsey, Norman F.

    1993-07-01

    The paper discusses current methods for accurate measurements of time by conventional atomic clocks, with particular attention given to the principles of operation of atomic-beam frequency standards, atomic hydrogen masers, and atomic fountain and to the potential use of strings of trapped mercury ions as a time device more stable than conventional atomic clocks. The areas of application of the ultraprecise and ultrastable time-measuring devices that tax the capacity of modern atomic clocks include radio astronomy and tests of relativity. The paper also discusses practical applications of ultraprecise clocks, such as navigation of space vehicles and pinpointing the exact position of ships and other objects on earth using the GPS.

  15. Experimental Determination of Phase Equilibria in the Silver-Copper Oxide System at High Temperature

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2007-06-01

    The phase diagram of silver-copper oxide was studied using thermal, microstructural and compositional analysis of quenched samples. The eutectic and monotectic temperature were found and compared to previous data. The miscibility gap was analyzed at higher temperatures than previous experimental work. The profile of the miscibility gap was found to extend from the monotectic composition and extend further into the copper rich portion than previously experimental work had show, which verifies a previous computational study.

  16. 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.

  17. Ab initio study of the hydroxide ion-water clusters: An accurate determination of the thermodynamic properties for the processes nH2O+OH-→HO-(H2O)n (n=1-4)

    NASA Astrophysics Data System (ADS)

    Pliego, Josefredo R.; Riveros, José M.

    2000-03-01

    Clusters of hydroxide ion, HO-(H2O)n=1-4, have been studied by high level ab initio calculations in order to better understand the first coordination shell of OH- ions. Geometry optimizations were performed at Hartree-Fock, density functional theory and second order Møller-Plesset perturbation theory levels using the 6-31+G(d,p) basis set. Single point energy calculations were carried out on the optimized geometries using the more extended 6-311+G(2df,2p) basis set and a higher level of electron correlation, namely fourth-order Møller-Plesset perturbation theory. For the n=1-3 clusters, only structures with the hydroxide ion hydrogen bonded to all waters molecules were considered. For the n=4 cluster, three minima were found; the most stable species has all four waters directly bound to the hydroxide ion, while the other two clusters have only three waters in the first coordination shell. In addition, the transition state connecting the cluster containing four waters in the first coordination shell to the species having three waters in the coordination shell was characterized. The barrier for this rearrangement is very low (1.82 kcal/mol), and we predict this process to occur on the picosecond time scale. The thermodynamic properties (enthalpy, entropy and Gibbs free energy) for the formation of the clusters have been calculated for all the species (including the fully deuterated clusters). Comparison of our calculations with experimental data reveals good agreement in the free energy. Nevertheless, our ab initio results suggest that for the n>1 clusters, both -ΔH0 and -ΔS0 are larger than those reported from experiment and new experiments may be necessary to obtain accurate experimental values.

  18. Accurate equilibrium structures of fluoro- and chloroderivatives of methane

    NASA Astrophysics Data System (ADS)

    Vogt, Natalja; Demaison, Jean; Rudolph, Heinz Dieter

    2014-11-01

    This work is a systematic study of molecular structure of fluoro-, chloro-, and fluorochloromethanes. For the first time, the accurate ab initio structure is computed for 10 molecules (CF4, CClF3, CCl2F2, CCl3F, CHClF2, CHCl2F, CH2F2, CH2ClF, CH2Cl2, and CCl4) at the coupled cluster level of electronic structure theory including single and double excitations augmented by a perturbational estimate of the effects of connected triple excitations [CCSD(T)] with all electrons being correlated and Gaussian basis sets of at least quadruple-ζ quality. Furthermore, when possible, namely for the molecules CH2F2, CH2Cl2, CH2ClF, CHClF2, and CCl2F2, accurate semi-experimental equilibrium (rSEe) structure has also been determined. This is achieved through a least-squares structural refinement procedure based on the equilibrium rotational constants of all available isotopomers, determined by correcting the experimental ground-state rotational constants with computed ab initio vibration-rotation interaction constants and electronic g-factors. The computed and semi-experimental equilibrium structures are in excellent agreement with each other, but the rSEe structure is generally more accurate, in particular for the CF and CCl bond lengths. The carbon-halogen bond length is discussed within the framework of the ligand close-packing model as a function of the atomic charges. For this purpose, the accurate equilibrium structures of some other molecules with alternative ligands, such as CH3Li, CF3CCH, and CF3CN, are also computed.

  19. The experimental determination of the moments of inertia of airplanes by a simplified compound-pendulum method

    NASA Technical Reports Server (NTRS)

    Gracey, William

    1948-01-01

    A simplified compound-pendulum method for the experimental determination of the moments of inertia of airplanes about the x and y axes is described. The method is developed as a modification of the standard pendulum method reported previously in NACA report, NACA-467. A brief review of the older method is included to form a basis for discussion of the simplified method. (author)

  20. 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.

  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. Molecular cage occupancy of clathrate hydrates at infinite dilution: experimental determination and thermodynamic significance.

    PubMed

    Seol, Jiwoong; Lee, Jong-Won; Kim, Do-Youn; Takeya, Satoshi; Ripmeester, John A; Lee, Huen

    2010-01-21

    This study focuses on the cage occupancy of guest molecules in the infinitely dilute state. At the extreme conditions of highly diluted guest concentrations the direct measurements of the cage occupancy ratio representing the competitive inclusion of multiguest species appear to be so difficult because of spectroscopic intensity limitation, but its thermodynamic significance might be considerable due to the fact that the infinite-dilution value of the cage occupancy ratio can provide the valuable thermodynamic information as a very unique and guest-specific parameter. To experimentally identify gaseous guest populations in structure I (sI) and structure II (sII) cages, we used the solid-state nuclear magnetic resonance (NMR), gas chromatography, and direct gas measurements. Furthermore, we derived the simple and generalized thermodynamic equation related to cage occupancies at infinite dilution from the van der Waals-Platteeuw model. Both experimental and predicted values agree well within the experimental error range. PMID:20000371

  3. Experimental determination and thermodynamic modeling of the Ni-Re binary system

    NASA Astrophysics Data System (ADS)

    Yaqoob, Khurram; Joubert, Jean-Marc

    2012-12-01

    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.

  4. Experimental and theoretical contributions to the determination of optical properties of synthetic paramelaconite

    SciTech Connect

    Pierson, J.F. Duverger, E.; Banakh, O.

    2007-03-15

    Paramelaconite (Cu{sub 4}O{sub 3}) is a metastable copper oxide that can be barely synthesised in 'pure' form. In this study, the reactive magnetron sputtering process was used to deposit Cu{sub 4}O{sub 3} films on silicon and glass substrates. The deposited films were characterised by X-ray diffraction (XRD), UV-visible-NIR spectroscopy and spectroscopic ellipsometry. For the first time, the refractive index and the extinction coefficient of Cu{sub 4}O{sub 3} were evaluated. The experimental values obtained from spectroscopic ellipsometry were compared to those calculated by a self-consistent approach using the Wien2k code. A very good agreement was found between the two sets of values. - Graphical abstract: Comparison between experimental (lines) and calculated (points) refractive index and extinction coefficient values. For experimental measurements, the film was deposited on silicon substrate.

  5. Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials

    SciTech Connect

    Soong, Ken

    2011-05-20

    The accelerating gradient in a laser-driven dielectric accelerating structure is often limited by the laser damage threshold of the structure. For a given laser-driven dielectric accelerator design, we can maximize the accelerating gradient by choosing the best combination of the accelerator's constituent material and operating wavelength. We present here a model of the damage mechanism from ultrafast infrared pulses and compare that model with experimental measurements of the damage threshold of bulk silicon. Additionally, we present experimental measurements of a variety of candidate materials, thin films, and nanofabricated accelerating structures.

  6. 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

  7. Accurate 12D dipole moment surfaces of ethylene

    NASA Astrophysics Data System (ADS)

    Delahaye, Thibault; Nikitin, Andrei V.; Rey, Michael; Szalay, Péter G.; Tyuterev, Vladimir G.

    2015-10-01

    Accurate ab initio full-dimensional dipole moment surfaces of ethylene are computed using coupled-cluster approach and its explicitly correlated counterpart CCSD(T)-F12 combined respectively with cc-pVQZ and cc-pVTZ-F12 basis sets. Their analytical representations are provided through 4th order normal mode expansions. First-principles prediction of the line intensities using variational method up to J = 30 are in excellent agreement with the experimental data in the range of 0-3200 cm-1. Errors of 0.25-6.75% in integrated intensities for fundamental bands are comparable with experimental uncertainties. Overall calculated C2H4 opacity in 600-3300 cm-1 range agrees with experimental determination better than to 0.5%.

  8. Experimental determination of neutron lifetimes through macroscopic neutron noise in the IPEN/MB-01 reactor

    SciTech Connect

    Gonnelli, Eduardo; Diniz, Ricardo

    2013-05-06

    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.

  9. 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.

  10. EXPERIMENTAL DETERMINATION OF CONTAMINANT METAL MOBILITY AS A FUNCTION OF TEMPERATURE, TIME, AND SOLUTION CHEMISTRY

    EPA Science Inventory

    We propose to determine the geochemical processes that control the mobility of Sr in the presence of clays (kaolinite, montmorillonite) and iron hydroxides (goethite) as a function of temperature, pH, and time. The objective of this work is to determine the fundamental data neede...

  11. Experimental method of determining the stress-strain state of bodies on the basis of the absorption of light

    SciTech Connect

    Myl`nikov, A.V.; Rudyak, Yu.A.

    1995-11-01

    Various analytical and experimental methods have been devised for determining stresses and strains in solids [1,2,4,5,6,7]. Among the experimental methods are optical methods based on the refraction and interference of light, polarization (photoelasticity), moire fringes, holographic effects, and other phenomena. All of these methods are based on changes in the index of refraction of electromagnetic waves as a result if the manifestation of optical anisotropy in loaded specimens made of special materials. They also rely on precise measurements of strains of loaded objects obtained by holographic techniques.

  12. Sensitivity of the interpretation of the experimental ion thermal diffusivity to the determination of the ion conductive heat flux

    SciTech Connect

    Stacey, W. M.

    2014-04-15

    A moments equation formalism for the interpretation of the experimental ion thermal diffusivity from experimental data is used to determine the radial ion thermal conduction flux that must be used to interpret the measured data. It is shown that the total ion energy flux must be corrected for thermal and rotational energy convection, for the work done by the flowing plasma against the pressure and viscosity, and for ion orbit loss of particles and energy, and expressions are presented for these corrections. Each of these factors is shown to have a significant effect on the interpreted ion thermal diffusivity in a representative DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] discharge.

  13. 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.

  14. 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. PMID:15752845

  15. Genome-wide experimental determination of barriers to horizontal gene transfer.

    PubMed

    Sorek, Rotem; Zhu, Yiwen; Creevey, Christopher J; Francino, M Pilar; Bork, Peer; Rubin, Edward M

    2007-11-30

    Horizontal gene transfer, in which genetic material is transferred from the genome of one organism to that of 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 Escherichia 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. Our data suggest that toxicity to the host inhibited transfer regardless of the species of origin and that increased gene dosage and associated increased expression may be a predominant cause for transfer failure. Although these experimental studies examined transfer solely into E. coli, a computational analysis of gene-transfer rates across available bacterial and archaeal genomes supports that the barriers observed in our study are general across the tree of life. PMID:17947550

  16. 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.

  17. Methods for determining the internal thrust of scramjet engine modules from experimental data

    NASA Technical Reports Server (NTRS)

    Voland, Randall T.

    1990-01-01

    Methods for calculating zero-fuel internal drag of scramjet engine modules from experimental measurements are presented. These methods include two control-volume approaches, and a pressure and skin-friction integration. The three calculation techniques are applied to experimental data taken during tests of a version of the NASA parametric scramjet. The methods agree to within seven percent of the mean value of zero-fuel internal drag even though several simplifying assumptions are made in the analysis. The mean zero-fuel internal drag coefficient for this particular engine is calculated to be 0.150. The zero-fuel internal drag coefficient when combined with the change in engine axial force with and without fuel defines the internal thrust of an engine.

  18. Experimental determination of the laminar separation bubble characteristics on an airfoil at low Reynolds numbers

    NASA Technical Reports Server (NTRS)

    Omeara, M. M.; Mueller, T. J.

    1986-01-01

    An experimental investigation was conducted in order to document the structure and behavior of laminar separation bubbles at low Reynolds numbers. Data of this type is necessary if the currently insufficient analytical and numerical models are to be improved. The laminar separation bubble which forms on a NACA 66(3)-018 airfoil model was surveyed at chord Reynolds numbers ranging from 50,000 to 200,000 at angles of attack from 8 to 12 degrees. The effects of the various testing conditions on the separation bubble were isolated, and the data was analyzed in relation to existing separation bubble correlations in order to test their low Reynolds number applicability. This analysis indicated that the chord Reynolds number and the disturbance environment strongly influence the experimental pressure distributions. These effects must be included in any analytic prediction technique applied to the low Reynolds number flight regime.

  19. Experimentally determining the locations of two astigmatic images for an underwater light source

    NASA Astrophysics Data System (ADS)

    Yang, Pao-Keng; Liu, Jian-You; Ying, Shang-Ping

    2015-05-01

    Images formed by an underwater object from light rays refracted in the sagittal and tangential planes are located at different positions for an oblique viewing position. The overlapping of these two images from the observer's perspective will thus prevent the image-splitting astigmatism from being directly observable. In this work, we present a heuristic method to experimentally visualize the astigmatism. A point light source is used as an underwater object and the emerging wave front is recorded using a Shack-Hartmann wave-front sensor. The wave front is found to deform from a circular paraboloid to an elliptic paraboloid as the viewing position changes from normal to oblique. Using geometric optics, we derive an analytical expression for the image position as a function of the rotating angle of an arm used to carry the wave-front sensor in our experimental setup. The measured results are seen to be in good agreement with the theoretical predictions.

  20. An ultrasonic theoretical and experimental approach to determine thickness and wave speed in layered media.

    PubMed

    de Sousa, Ana Valéria Greco; Pereira, Wagner Coelho de Albuquerque; Machado, João Carlos

    2007-02-01

    This work presents an ultrasonic method to characterize the layers of a stratified medium, using independent measurements of wave speed and thickness of each layer. The model, based on geometrical acoustics, includes refraction. Two transducers are used: one active (3.4 MHz) and a hydrophone as a receptor, which is moved laterally through 15 positions. The distance between the transducers and the delay between the echoes, from the interfaces separating the layers, received by them are used to estimate the speed and thickness. Three types of layered phantoms were used: Ph1 made with alcohol/acrylic, Ph2 made with polyvinyl chloride/water/acrylic, and Ph3 made with acrylic/water/polyvinyl chloride. The experimental results for speed of sound and layer thickness presented an experimental mean relative error, for thickness and wave speed, lower than 7.0% and 6.6%, respectively. PMID:17328335

  1. Experimental determination of turbulent buffeting effects in tube bundles: Final report

    SciTech Connect

    Johnson, J.E.; Simonis, J.C.

    1988-05-01

    Dynamic lift and drag force correlations for the first and second row of tubes of a square pitch tube array (P/D=1.44) are presented for upstream turbulence intensity and integral scale lengths. These correlations were developed from experimental testing of full scale heat exchanger tubes in water under controlled and measured turbulent flow conditions. Turbulent buffeting effects for upstream turbulence intensities up to 15% and scale lengths of /1/2/ to 1 tube diameter are discussed.

  2. 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.

  3. 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. PMID:24211950

  4. Determination of localization accuracy based on experimentally acquired image sets: applications to single molecule microscopy.

    PubMed

    Tahmasbi, Amir; Ward, E Sally; Ober, Raimund J

    2015-03-23

    Fluorescence microscopy is a photon-limited imaging modality that allows the study of subcellular objects and processes with high specificity. The best possible accuracy (standard deviation) with which an object of interest can be localized when imaged using a fluorescence microscope is typically calculated using the Cramér-Rao lower bound, that is, the inverse of the Fisher information. However, the current approach for the calculation of the best possible localization accuracy relies on an analytical expression for the image of the object. This can pose practical challenges since it is often difficult to find appropriate analytical models for the images of general objects. In this study, we instead develop an approach that directly uses an experimentally collected image set to calculate the best possible localization accuracy for a general subcellular object. In this approach, we fit splines, i.e. smoothly connected piecewise polynomials, to the experimentally collected image set to provide a continuous model of the object, which can then be used for the calculation of the best possible localization accuracy. Due to its practical importance, we investigate in detail the application of the proposed approach in single molecule fluorescence microscopy. In this case, the object of interest is a point source and, therefore, the acquired image set pertains to an experimental point spread function. PMID:25837101

  5. Experimental determination of series resistance of p-n junction diodes and solar cells

    NASA Technical Reports Server (NTRS)

    Chen, P. J.; Pao, S. C.; Neugroschel, A.; Lindholm, F. A.

    1978-01-01

    Various methods for determining the series resistance of p-n junction diodes and solar cells are described and compared. New methods involving the measurement of the ac admittance are shown to have certain advantages over methods proposed earlier.

  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. Experimentally Determining the Molar Mass of Carbon Dioxide Using a Mylar Balloon.

    ERIC Educational Resources Information Center

    Jackson, Barbara Albers; Crouse, David J.

    1998-01-01

    Describes how to determine the mass of a gas in a flexible, lightweight container and argues that the buoyant force of air needs to be taken into account. Recommends the use of mylar and describes equipment preparation. (DDR)

  8. 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)

  9. Experimental determination of correlations for mean heat transfer coefficients in plate fin and tube heat exchangers

    NASA Astrophysics Data System (ADS)

    Taler, Dawid

    2012-09-01

    This paper presents a numerical method for determining heat transfer coefficients in cross-flow heat exchangers with extended heat exchange surfaces. Coefficients in the correlations defining heat transfer on the liquid- and air-side were determined using a nonlinear regression method. Correlation coefficients were determined from the condition that the sum of squared liquid and air temperature differences at the heat exchanger outlet, obtained by measurements and those calculated, achieved minimum. Minimum of the sum of the squares was found using the Levenberg-Marquardt method. The uncertainty in estimated parameters was determined using the error propagation rule by Gauss. The outlet temperature of the liquid and air leaving the heat exchanger was calculated using the analytical model of the heat exchanger.

  10. Using experimental measurements of three-level avoided crossings to determine the quantum defect for the Stark map of highly excited cesium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Wang, Limei; Li, Changyong; Zhang, Hao; Zhang, Linjie; Yang, Yonggang; Man, Yuan; Zhao, Jianming; Jia, Suotang

    2016-03-01

    The spectra of Rydberg atoms in the domain of three-level avoided crossings formed by the Rydberg 49 S1 /2 state and high-l states in the n =45 manifold are observed in the standard magneto-optical trap of cesium. We develop a highly accurate method which uses the spectroscopic results in order to refine the quantum defect of the 49 S1 /2 state from the previous value 4.0495 ±0.0001 extrapolated from n =6 -30 S states [K. H. Weber and C. J. Sansonetti, Phys. Rev. A 35, 4650 (1987), 10.1103/PhysRevA.35.4650] to the new value 4.049 78 ±0.000 03 . For this purpose, we determine two characteristic properties of the avoided crossings: (i) the minimum gap between the upper and the lower levels, and (ii) the value of equal gaps between the upper and the middle levels and between the middle and the lower levels. The experimental results for the avoided crossing near 4 V/cm are (i) (111.7 ±1.3 )h MHz , and (ii) (57.0 ±2.1 )h MHz . For comparison, quantum mechanical simulations based on the published quantum defect yield (i) 109.52 h MHz , and (ii) 56.04 h MHz . The refined quantum defect is adjusted such that it yields (i) 111.50 h MHz , and (ii) 56.98 h MHz , in even better agreement with the experimental results. The theoretical values of the electric fields for (i) and (ii) differ by 0.03 V/cm, in perfect agreement with the experimental results. The refinement also improves the agreement of their absolute values. The remaining ˜1.5% difference is attributed to effects of stray fields.

  11. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  12. Experimental and Monte Carlo determination of the TG-43 dosimetric parameters for the model 9011 THINSeed brachytherapy source

    SciTech Connect

    Kennedy, R. M.; Davis, S. D.; Micka, J. A.; DeWerd, L. A.

    2010-04-15

    Purpose: AAPM TG-43 brachytherapy dosimetry parameters for a new, smaller diameter {sup 125}I brachytherapy source (THINSeed, model 9011) were determined using LiF:Mg,Ti thermoluminescent dosimeter (TLD-100) microcubes and Monte Carlo simulations. Methods: Two polymethyl methacrylate phantoms were machined to hold TLD-100 microcubes at specific locations for the experimental determination of the radial dose function, dose-rate constant, and anisotropy functions of the new source. The TG-43 parameters were also calculated using Monte Carlo simulations. For comparison, the model 6711 source was also investigated. Results: Experimental results for both models 9011 and 6711 sources showed good agreement with Monte Carlo values, as well as with previously published values. Conclusions: The TG-43 parameters for the new source model are similar to those of model 6711; however, they represent two separate sources and TG-43 parameters used in treatment planning must be source specific.

  13. 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…

  14. Accurate ab Initio Spin Densities

    PubMed Central

    2012-01-01

    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]. PMID:22707921

  15. 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.

  16. 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. PMID

  17. Comparison of Experimental and Theoretical Determined Terahertz Attenuation in Controlled Rain

    NASA Astrophysics Data System (ADS)

    Ma, Jianjun; Vorrius, Francis; Lamb, Lucas; Moeller, Lothar; Federici, John F.

    2015-12-01

    The effects of rain attenuation on 0.1- to 1-THz frequencies are reported in this paper. The THz pulses propagate through a rain chamber over a 4-m distance and are measured by THz time-domain spectroscopy (THz-TDS). A rain chamber is designed to generate controllable and reproducible rain conditions with different intensities. Image analysis software is employed to characterize the distribution of generated raindrop sizes. Theoretical THz power attenuations due to rain are calculated using Mie scattering theory and are compared with our measurements. Results show that both experimental and theoretical results are in very good agreement with each other.

  18. Experimental determination of resonant frequencies by transient scattering from conducting spheres and cylinders

    NASA Astrophysics Data System (ADS)

    Tseng, F.-I.; Sarkar, T. K.

    1984-09-01

    A new experimental technique to measure resonant frequencies of a target is presented. A Tektronix WP 1310 waveform processing system has been employed, which features signal processing software with extensive control over instruments, waveform manipulations, and graphic display. Numerous transient waveforms scattered from spheres and cylinders of various sizes have been recorded. A recently developed data-processing technique has been described and applied to these transient waveforms to extract their resonant frequencies. With the use of a new window designed to have a low near-sidelobe level, the modified fast Fourier transform (FFT) is shown to be able to improve the measurement capability of the system.

  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. 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.