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Sample records for surface debye-waller factor

  1. On the Debye-Waller factor in atom-surface scattering

    International Nuclear Information System (INIS)

    Garcia, N.; Maradudin, A.A.; Celli, V.

    1982-01-01

    A theory for the Debye-Waller factor in atom-surface scattering is presented, to lowest order in the phonon contributions. Multiple-scattering effects as well as the cross-correlated surface atom displacements are included. The theory accounts for experimental data without the necessity of introducing the Armand effect, which is due to the finite size of the incident atom. The work presented here implies that the Kirchhoff approximation fails when the energy of the incident particle is in the energy range of the phonon spectrum. The results of the calculation are presented in the high-temperature limit, and it is observed that the Rayleigh surface phonons contribute three-quarters of the Debye-Waller factor, while the bulk phonons account for the rest. This result is interesting because the calculation of the former contribution is simpler than that of the latter. (author)

  2. Debye-Waller factors of the light actinide metals

    International Nuclear Information System (INIS)

    Lawson, A.C.; Goldstone, J.A.; Cort, B.; Sheldon, R.I.; Foltyn, E.M.

    1994-01-01

    The authors have been using time-of-flight neutron powder diffraction to determine the Debye-Waller factors of the light actinide metals. The Debye-Waller factor is a measure of the mean-square atomic displacement that arises from the thermal motion of the atoms in any solid. Its temperature dependence determines a Debye-Waller temperature, Θ DW , that is characteristic of the elastic properties of the solid. The data are obtained by Rietveld analysis of neutron diffraction powder patterns obtained at several temperatures. The authors will present results for α-U, α-Np, α-Pu and σ-Pu 0.95 Al 0.05 . The Θ DW 's are temperature dependent, and anharmonic interatomic forces seem to be required to explain the results

  3. Debye-Waller Factor in Neutron Scattering by Ferromagnetic Metals

    Science.gov (United States)

    Paradezhenko, G. V.; Melnikov, N. B.; Reser, B. I.

    2018-04-01

    We obtain an expression for the neutron scattering cross section in the case of an arbitrary interaction of the neutron with the crystal. We give a concise, simple derivation of the Debye-Waller factor as a function of the scattering vector and the temperature. For ferromagnetic metals above the Curie temperature, we estimate the Debye-Waller factor in the range of scattering vectors characteristic of polarized magnetic neutron scattering experiments. In the example of iron, we compare the results of harmonic and anharmonic approximations.

  4. Pressure effects in Debye-Waller factors and in EXAFS

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Van Hung, E-mail: hungnv@vnu.edu.v [University of Science, VNU Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Vu Van Hung [Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Ho Khac Hieu [University of Science, VNU Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); National University of Civil Engineering, 55 Giai Phong, Hai Ba Trung, Hanoi (Viet Nam); Frahm, Ronald R. [Bergische Universitaet-Gesamthochschule Wuppertal, FB: 8-Physik, Gauss Strasse 20, 42097 Wuppertal (Germany)

    2011-02-01

    Anharmonic correlated Einstein model (ACEM) and statistical moment method (SMM) have been developed to derive analytical expressions for pressure dependence of the lattice bond length, effective spring constant, correlated Einstein frequency and temperature, Debye-Waller factors (DWF) or second cumulant, first and third cumulants in Extended X-ray Absorption Fine Structure (EXAFS) at a given temperature. Numerical results for pressure-dependent DWF of Kr and Cu agree well with experiment and other theoretical values. Simulated EXAFS of Cu and its Fourier transform magnitude using our calculated pressure-induced change in the 1st shell are found to be in a reasonable agreement with those using X-ray diffraction (XRD) experimental results. -- Research Highlights: {yields} We have developed anharmonic correlated Einstein model and statistical moment method. {yields} The pressure effects in cumulants including DWF and in EXAFS has been investigated. {yields} Calculated pressure-dependent DWF for Kr, Cu agree with experiment and other results. {yields} Simulated EXAFS and Fourier transform magnitude of Cu agree with those using XRD data.

  5. Pressure effects in Debye-Waller factors and in EXAFS

    International Nuclear Information System (INIS)

    Nguyen Van Hung; Vu Van Hung; Ho Khac Hieu; Frahm, Ronald R.

    2011-01-01

    Anharmonic correlated Einstein model (ACEM) and statistical moment method (SMM) have been developed to derive analytical expressions for pressure dependence of the lattice bond length, effective spring constant, correlated Einstein frequency and temperature, Debye-Waller factors (DWF) or second cumulant, first and third cumulants in Extended X-ray Absorption Fine Structure (EXAFS) at a given temperature. Numerical results for pressure-dependent DWF of Kr and Cu agree well with experiment and other theoretical values. Simulated EXAFS of Cu and its Fourier transform magnitude using our calculated pressure-induced change in the 1st shell are found to be in a reasonable agreement with those using X-ray diffraction (XRD) experimental results. -- Research Highlights: → We have developed anharmonic correlated Einstein model and statistical moment method. → The pressure effects in cumulants including DWF and in EXAFS has been investigated. → Calculated pressure-dependent DWF for Kr, Cu agree with experiment and other results. → Simulated EXAFS and Fourier transform magnitude of Cu agree with those using XRD data.

  6. The Temperature Dependence of the Debye-Waller Factor of Magnesium

    DEFF Research Database (Denmark)

    Sledziewska-Blocka, D.; Lebech, Bente

    1976-01-01

    The temperature dependence of the average Debye-Waller factor for magnesium was measured by means of neutron diffraction spectrometry. The experimental results obtained in the temperature range from 5 to 256 K are compared with theoretical calculations, using the harmonic and quasi-harmonic appro......The temperature dependence of the average Debye-Waller factor for magnesium was measured by means of neutron diffraction spectrometry. The experimental results obtained in the temperature range from 5 to 256 K are compared with theoretical calculations, using the harmonic and quasi......-harmonic approximations and results of previous experiments....

  7. Lattice dynamical appraisal of the anisotropic Debye-Waller factors in graphite lattice

    International Nuclear Information System (INIS)

    Haridasan, T.M.; Sathyamurthy, G.

    1989-12-01

    The Debye-Waller factors in graphite for the atomic motions within the basal plane and also across the basal planes have been calculated using the various lattice dynamical models available to date and a critical comparison is made with the existing experimental data from X ray and neutron scattering studies. The present study reveals the need for further investigation on the nature of atomic motion across the basal planes. (author). 15 refs, 1 tab

  8. XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes

    Science.gov (United States)

    Dimakis, Nicholas; Bunker, Grant

    2007-02-01

    We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained.

  9. XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes

    International Nuclear Information System (INIS)

    Dimakis, Nicholas; Bunker, Grant

    2007-01-01

    We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained

  10. The primary extinction and static Debye-Waller factor in the characterization of textured nickel by X-ray diffraction

    International Nuclear Information System (INIS)

    Kryshtab, T.; Palacios G, J.; Cadena A, A.; Kryvko, A.

    2015-01-01

    The texture analysis using X-ray diffraction (XRD) implies measurement of pole figures (Pf) from the diffracted intensities considering the model of kinematical dispersion. The extinction phenomenon results in a decrease of diffracted intensity and that in turn in a decrease of pole densities (Pds). The phenomenon appears in the kinematical theory of XRD as the primary extinction and the secondary extinction to characterize the loss of intensity of kinematical dispersion. In turn, the static Debye-Waller factor is an integral characteristic of defects in crystals that is introduced in the kinematical theory of XRD and also is used in dynamical theory of XRD. In this work the correlation between the primary extinction coefficient and the static Debye-Waller factor in the case of textured nickel was determined. The value of static Debye-Waller factor was determined from the value of the calculated primary extinction coefficient. For the evaluation there were used Pds in the maxima of Pf obtained for 111 and 200 reflections with Mo Kα radiation, and the Pds in the maxima of Pf obtained for the first and second orders of these reflections with Cu Kα and Co Kα radiations. There were calculated the dislocation densities in grains using values of static Debye-Waller factor and the extinction coefficients. The dislocation densities calculated from these two characteristics are practically equal. (Author)

  11. Determination of the Debye-Waller Factor of hydrogen in Palladium and Palladium Silver alloy

    International Nuclear Information System (INIS)

    Khodabakhsh, R.

    1986-01-01

    The mean square amplitude of the vibrating hydrogen in metals can be determined by using coherent elastic neutron scattering experiments, inelastic one-phonon scattering measurements. To determine the D.W.F. Debye-Waller Factor from the coherent elastic scattering measurements, information about the positions of atoms within the unit is required, and vice versa. The main difficulty concerning the determination of the D.W.F. from the inelastic experiment is in elimination of multi-phonon contribution from the measured spectrum. However, the D.W.F. of hydrogen in palladium has been usually determined by the intensity of the quasi-elastic line. An integration of the measured scattering law S(Q,W) at constant Q, over a certain energy window ΔE, results in the quasi-elastic intensity. To obtain an accurate result, this window has to be chosen large enough to comprise most of the quasi-elastic line, but sufficiently small so that the phonon contributions are small. The MARX spectrometer is ideally constructed for this type of measurement where the window is about +-1 Mev for incident neutron wavelength, =4.115 A. Thus, the quasi-elastic scattering method was considered the best method of determining the D.W.F. of hydrogen in palladium using the MARX spectrometer. However, if the acoustic part overlaps with the quasi-elastic part, one has to obtain the D.W.F. by fitting the data to a quasi-elastic model. The work to be reported here is the investigation of variations of the D.W.F. of hydrogen in Pd and PdAgsub(0.085) with temperature and extension of the available data to as high a temperature as possible. Therefore the integrated intensity of incoherent quasi-elastic neutron scattering by proton in polycrystallin Pd/H and PdAgsub(0.085)/H was investigated as a function of the scattering vector Q. A quasi-harmonic D.W.F. behaviour was observed at elevated temperatures. The observed Debye-Waller Factor depends strongly on the form of the amplitude weighted frequency

  12. Thermal behaviour of the Debye-Waller factor and the specific heat of anharmonic crystals

    International Nuclear Information System (INIS)

    Lima, R.A.T. de; Tsallis, C.

    1979-08-01

    The influence of the cubic and quartic crystalline anharmonicity on the classical and quantum thermal behaviour of the specific heat, Debye temperaturetheta, Debye-Waller factor W, crystalline expansion and phonon spectrum is studied, within the framework of the Variational Method in Statistical Mechanics. The sistems, mainly focalized are the single oscillator, the mono-atomic linear chain and simple cubic crystal. The trial Hamiltonian is an harmonic one, therefore the various anharmonic influences are mainly absorbed into the renormalization of theta(T). Several differences between the classical and quantum results are exhibited. Satisfactory qualitative agreement with experience was obtained in the low-temperature regime, in particular in what concerns the existence of a minimum in theta(T) which has been observed in Cu, Al, Ag, Au and Pb. For the intermediate-temperature regime the customary linear behaviour of W(T) (hence theta(T) almost constant) is reobtained. Finally in the high-temperature regime, the present treatment leads to a √T - dependence for the W-factor, which implies in the wrong curvature with respect to experimental data. A possible explanation of this disagreement might be related to the melting phenomenon, which is not covered by the present theory. (Author) [pt

  13. Search for anisotropy in the Debye-Waller factor of HCP solid 4He

    Science.gov (United States)

    Barnes, Ashleigh L.; Hinde, Robert J.

    2016-02-01

    The properties of hexagonal close packed (hcp) solid 4He are dominated by large atomic zero point motions. An accurate description of these motions is therefore necessary in order to accurately calculate the properties of the system, such as the Debye-Waller (DW) factors. A recent neutron scattering experiment reported significant anisotropy in the in-plane and out-of-plane DW factors for hcp solid 4He at low temperatures, where thermal effects are negligible and only zero-point motions are expected to contribute. By contrast, no such anisotropy was observed either in earlier experiments or in path integral Monte Carlo (PIMC) simulations of solid hcp 4He. However, the earlier experiments and the PIMC simulations were both carried out at higher temperatures where thermal effects could be substantial. We seek to understand the cause of this discrepancy through variational quantum Monte Carlo simulations utilizing an accurate pair potential and a modified trial wavefunction which allows for anisotropy. Near the melting density, we find no anisotropy in an ideal hcp 4He crystal. A theoretical equation of state is derived from the calculated energies of the ideal crystal over a range of molar volumes from 7.88 to 21.3 cm3, and is found to be in good qualitative agreement with experimental data.

  14. Ab Initio Calculation of XAFS Debye-Waller Factors for Crystalline Materials

    Science.gov (United States)

    Dimakis, Nicholas

    2007-02-01

    A direct an accurate technique for calculating the thermal X-ray absorption fine structure (XAFS) Debye-Waller factors (DWF) for materials of crystalline structure is presented. Using the Density Functional Theory (DFT) under the hybrid X3LYP functional, a library of MnO spin—optimized clusters are built and their phonon spectrum properties are calculated; these properties in the form of normal mode eigenfrequencies and eigenvectors are in turn used for calculation of the single and multiple scattering XAFS DWF. DWF obtained via this technique are temperature dependent expressions and can be used to substantially reduce the number of fitting parameters when experimental spectra are fitted with a hypothetical structure without any ad hoc assumptions. Due to the high computational demand a hybrid approach of mixing the DFT calculated DWF with the correlated Debye model for inner and outer shells respectively is presented. DFT obtained DWFs are compared with corresponding values from experimental XAFS spectra on manganosite. The cluster size effect and the spin parameter on the DFT calculated DWFs are discussed.

  15. X-ray Debye-Waller factor measurements of solid 3He and 4He

    International Nuclear Information System (INIS)

    Arms, D.A.; Shah, R.S.; Simmons, R.O.

    2003-01-01

    X-ray synchrotron radiation was used to measure Debye-Waller factors of helium crystals for both 3 He and 4 He in both hcp and fcc phases. To our knowledge, there are no previous measurements for 3 He. The ranges studied for 3 He and 4 He crystals were 11.52-12.82 and 10.95-12.13 cm 3 , respectively, and 11.5-18.2 and 12.0-20.3 K. With small uncertainty, only a Gaussian dependence upon momentum transfer Q was found, and no anisotropy was detected in the hcp phase. Mean square atomic deviations, 2 >, and Lindemann ratios were obtained. Large Lindemann ratios confirm that these solids are highly anharmonic. The 2 > values agree within an average 1% with computations of Draeger and Ceperley from path integral Monte Carlo methods including unusual extrapolations to the thermodynamic limit. Because the path-integral Monte Carlo (PIMC) computations exhibit a T 3 dependence for 2 >, which also depends upon molar volume, an empirical analysis was made of the present data as well as of published x-ray and neutron data on hcp 4 He. The volume dependencies are similar to those found from calorimetry, over a large volume range, and the temperature dependencies show similar systematic variations with molar volume both in x-ray data and PIMC results

  16. Anharmonic correlated Debye model high-order expanded interatomic effective potential and Debye-Waller factors of bcc crystals

    Energy Technology Data Exchange (ETDEWEB)

    Van Hung, Nguyen, E-mail: hungnv@vnu.edu.vn [Department of Physics, Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Hue, Trinh Thi [Department of Physics, Hanoi University of Science, 334 Nguyen Trai, Thanh Xuan, Hanoi (Viet Nam); Khoa, Ha Dang [School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Vuong, Dinh Quoc [Quang Ninh Education & Training Department, Nguyen Van Cu, Ha Long, Quang Ninh (Viet Nam)

    2016-12-15

    High-order expanded interatomic effective potential and Debye-Waller factors (DWFs) for local vibrational amplitudes in X-ray absorption fine structure (XAFS) of bcc crystals have been studied based on the anharmonic correlated Debye model. DWFs are presented in terms of cumulant expansion up to the fourth order and the many-body effects are taken into account in the present one-dimensional model based on the first shell near neighbor contribution approach used in the derivations of the anharmonic effective potential and XAFS cumulants where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for the dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS cumulants have been derived based on the many-body perturbation approach. Thermodynamic properties and anharmonic effects in XAFS of bcc crystals described by the obtained cumulants have been in detail discussed. The advantage and efficiency of the present theory are illustrated by good agreement of the numerical results for Mo, Fe and W with experiment.

  17. The primary extinction and static Debye-Waller factor in the characterization of textured nickel by X-ray diffraction; La extincion primaria y el factor estatico de Debye-Waller en la caracterizacion de niquel con textura mediante difraccion de rayos X

    Energy Technology Data Exchange (ETDEWEB)

    Kryshtab, T.; Palacios G, J. [Instituto Politecnico Nacional, Escuela Superior de Fisica y Matematicas, Av. IPN s/n, 07738 Mexico D. F. (Mexico); Cadena A, A. [Instituto Politecnico Nacional, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, Av. IPN s/n, 07738 Mexico D. F. (Mexico); Kryvko, A., E-mail: kryshtab@gmail.com [Instituto Politecnico Nacional, Escuela Superior de Ingenieria Mecanica y Electrica, Unidad Zacatenco, 07360 Mexico D. F. (Mexico)

    2015-07-01

    The texture analysis using X-ray diffraction (XRD) implies measurement of pole figures (Pf) from the diffracted intensities considering the model of kinematical dispersion. The extinction phenomenon results in a decrease of diffracted intensity and that in turn in a decrease of pole densities (Pds). The phenomenon appears in the kinematical theory of XRD as the primary extinction and the secondary extinction to characterize the loss of intensity of kinematical dispersion. In turn, the static Debye-Waller factor is an integral characteristic of defects in crystals that is introduced in the kinematical theory of XRD and also is used in dynamical theory of XRD. In this work the correlation between the primary extinction coefficient and the static Debye-Waller factor in the case of textured nickel was determined. The value of static Debye-Waller factor was determined from the value of the calculated primary extinction coefficient. For the evaluation there were used Pds in the maxima of Pf obtained for 111 and 200 reflections with Mo Kα radiation, and the Pds in the maxima of Pf obtained for the first and second orders of these reflections with Cu Kα and Co Kα radiations. There were calculated the dislocation densities in grains using values of static Debye-Waller factor and the extinction coefficients. The dislocation densities calculated from these two characteristics are practically equal. (Author)

  18. Phasons modulate the atomic Debye-Waller factors in incommensurate structures: Experimental evidence in ThBr4 at 55 K

    International Nuclear Information System (INIS)

    Madariaga, G.; Perez-Mato, J.M.; Aramburu, I.

    1993-01-01

    The incommensurate displacive structure of β-ThBr 4 at 55 K has been determined from a neutron diffraction data set including main reflections and first-order satellites. The superspace group is Psub(s anti 1 s1)sup(I4 1 /amd). Final agreement factors are 0.0193, 0.0186 and 0.045 for all, main and satellite reflections, respectively. It is shown that the effect of phasons on the atomic Debye-Waller factors can be quantified by two additional structural parameters: The modulus β 11,2 Br and the phase χ 11,2 Br of a second harmonic that spatially modulates the temperature factors of Br atoms. Results are in good agreement, within the resolution of the experimental data, with the theoretically expected value for χ 11,2 Br . Crystal data for the average structure: M r =551.65, tetragonal, I4 1 /amd, a=8.919(1), c=7.902(1) A, V=628.6(2) A 3 , Z=4, D x =5.82 Mg m -3 , λ=0.84 A, wavevector q=0.32c*. (orig.)

  19. Effect of anharmonicity and Debye-Waller factor on the superconductivity of PdHsub(x) and PdDsub(x)

    International Nuclear Information System (INIS)

    Griessen, R.; Groot, D.G. de

    1983-01-01

    On the basis of existing superconducting tunnelling, neutron scattering, electrical resistivity and Raman scattering data and new thermal expansion, elastic moduli and point-contact spectroscopy data it is concluded that the anharmonicity of the proton (deuteron)-palladium potential is such that Msub(H)#betta#sub(H) 2 /(Msub(D)#betta#sub(D) 2 ) = 1.12 +- 0.05 Msub(H(D)) is the mass and #betta#sub(H(D)) the frequency of the vibration of hydrogen (deuterium). This anharmonicity is approximately 2 times too weak to reproduce the observed inverse isotope effect in the superconducting transition temperature of concentrated PdHsub(x) and PdDsub(x) alloys. Within a pseudopotential formalism it is shown that the Debye-Waller factor arising from the large zero-point amplitude of the interstitial hydrogen (deuterium) leads to a contribution to the inverse isotope effect in Tsub(c) which is as large as that of anharmonicity alone. (Auth.)

  20. An alternative explanation of the change in T-dependence of the effective Debye-Waller factor at T{sub c} or T{sub B}

    Energy Technology Data Exchange (ETDEWEB)

    Ngai, K. L. [Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy); CNR-IPCF, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); Habasaki, J. [Tokyo Institute of Technology, Yokohama 226-8502 (Japan)

    2014-09-21

    The cusp-like temperature dependence of the Debye-Waller factor or non-ergodicity parameter f{sub Q}(T) at some temperature T{sub c} above T{sub g} found by experiments in several fragile glassformers has been considered as critical evidence for validity of the ideal Mode Coupling Theory (MCT). A comprehensive review of experimental data of f{sub Q}(T) and beyond brings out various problems of the MCT predictions. For example, the molten salt, 0.4Ca(NO{sub 3}){sub 2}-0.6KNO{sub 3} (CKN), was the first glassformer measured by neutron scattering to verify the cusp-like behavior of f{sub Q}(T) at T{sub c} predicted by ideal MCT. While the fits of the other scaling laws of MCT to viscosity, light scattering, and dielectric relaxation data all give T{sub c} in the range from 368 to 375 K, there is no evidence of cusp-like behavior of f{sub Q}(T) at T{sub c} from more accurate neutron scattering data obtained later on by Mezei and Russina [J. Phys.: Condens. Matter 11, A341 (1999)] at temperatures below 400 K. In several molecular glass-formers, experiments have found at temperatures below T{sub c} that [1−f{sub Q}(T)] is manifested as nearly constant loss (NCL) in the frequency dependent susceptibility. The NCL persists down to below T{sub g} and is not predicted by the ideal MCT. No clear evidence of the change of T-dependence of f{sub Q}(T) at any T{sub c} was found in intermediate and strong glassformers, although ideal MCT does not distinguish fragile and strong glassformers in predicting the critical behavior of f{sub Q}(T) a priori. Experiments found f{sub Q}(T) changes T-dependence not only at T{sub c} but also at the glass transition temperature T{sub g}. The changes of T-dependence of f{sub Q}(T) at T{sub c} and T{sub g} are accompanied by corresponding changes of dynamic variables and thermodynamic quantities at T{sub B} ≈ T{sub c} and at T{sub g}. The dynamic variables include the relaxation time τ{sub α}(T), the non-exponentiality parameter n(T), and

  1. A computer program for lattice-dynamical evaluation of Debye-Waller factors and thermodynamic functions for minerals, starting from empirical force fields

    International Nuclear Information System (INIS)

    Pilati, T.; Dermartin, F.; Gramaccioli, C.M.

    1993-01-01

    A wide-purpose computer program has been written (Fortran) for lattice dynamical evaluation of crystallographic and thermodynamic properties of solids, especially minerals or inorganic substances.The program essentially consists of a routine affording first and second derivatives of energy with respect to mass weighted coordinates, properly modulated by a wave vector algorithm, so that diagonalization can immediately follow and arrive at frequencies, density of states, and eventually to thermodynamic functions and Debye-Waller parameters thorough an automatic Brillouin-zone sampling procedure. The input consists of crystallographic data (unit-cell parameters, space group symmetry operations, atomic coordinates), plus atomic charge and empirical parameters, such as force constants or non-bonded atom-atom interaction energy functions in almost any form. It is also possible to obtain the structure corresponding to the energy minimum, or even to work with partial rigid bodies, in order to reduce the order of the dynamical matrices. The program provides for automatic symmetry labelling of the vibrational modes, in order to compare them with the experimental data; there is possibility of improving the empirical functions through a minimization routine. Examples of application and transferability of force fields to a series of minerals are provided. (author)

  2. Laser ablation characteristics of metallic materials: Role of Debye-Waller thermal parameter

    International Nuclear Information System (INIS)

    Butt, M Z

    2014-01-01

    The interaction of a high intensity laser pulse with a solid target results in the formation of a crater and a plasma plume. The characteristics of both depend on physical properties of target material, environmental conditions, and laser parameters (e.g. wavelength, pulse duration, energy, beam diameter) etc. It has been shown for numerous metals and their alloys that plasma threshold fluence, plasma threshold energy, ablation efficiency, ablation yield, angular distribution of laser produced plasma (LPP) ions, etc. are a unique function of the Debye-Waller thermal parameter B or the mean-square amplitude of atomic vibration of the target material for given experimental conditions. The FWHM of the angular distribution of LPP ions, ablation yield, and ablation efficiency increase whereas plasma threshold fluence and plasma threshold energy decrease as B-factor of the target material increases

  3. Theory of the particle matrix elements for Helium atom scattering in surfaces

    International Nuclear Information System (INIS)

    Khater, A.; Toennies, J.P.

    2000-01-01

    Full text.A brief review is presented for the recent development of the theory of the particle transition matrix elements, basic to the cross section for Helium and inert particle scattering at thermal energies in solid surfaces. the Jackson and Mott matrix elements are presented and discussed for surface scattering processes, habitually classified as elastic and inelastic. Modified transition matrix elements, introduced originally to account for the cut-off effects, are presented in a direct and simple manner. the Debye-Waller factor is introduced and discussed. A recent calculation for the particle transition matrix elements is presented for the specular and inelastic transition matrix elements and the corresponding inelastic scattering cross section is compared in detail to experimental data. the specular and inelastic transition matrix elements are found to be intrinsically similar owing to the intermediate role of a proposed virtual particle squeezed state near the surface

  4. Evaluation of the roughness of a crystal surface by X-ray scattering. Pt. 1

    International Nuclear Information System (INIS)

    Harada, Jimpei

    1992-01-01

    The relationship between the intensity distributions of the crystal truncation rod (CTR) scattering and the surface roughness of a crystal is discussed by developing a kinematic theory for the CTR scattering so as to reflect the two-dimensional aspect of the surface. The intensity of the CTR scattering elongated from a Bragg point is shown to be reduced by a factor vertical strokeΓ(q)vertical stroke 2 for a surface possessing some roughness, where Γ(q) is defined by a simple Fourier summation of γ p , the relative area with the same step height p on a surface, i.e. Γ(q) = Σ ∞ p=o γ p exp (2πipq), with Σ p γ p = 1, q being the distance in reciprocal space from the Bragg point along the CTR scattering. A pair-correlation function between the steps can, therefore, be obtained by a simple Fourier integral of the roughness damping factor vertical strokeΓ(q)vertical stroke 2 . For the case where γ p has a Gaussian distribution around the average step height, vertical strokeΓ(q)vertical stroke 2 is approximated by the well known Debye-Waller-like factor, exp (K- 4π 2 (Δp 2 )q 2 ), where (Δp 2 ) is the mean square deviation of step height in units of the lattice spacing. The intensity formulae proposed so far by several authors are also discussed on the basis of the above factor. (orig.)

  5. Diffractive scattering of H atoms from the (001) surface of LiF at 78 K

    International Nuclear Information System (INIS)

    Caracciolo, G.; Iannotta, S.; Scoles, G.; Valbusa, U.

    1980-01-01

    We have built an apparatus for the measurement of high resolution diffractive scattering of hydrogen atoms from crystal surfaces. The apparatus comprises a hydrogen atom beam source, a hexapolar magnetic field velocity selector, a variable temperature UHV crystal manipulator, and a rotatable bolometer detector. The diffraction pattern of a beam of hydrogen atoms scattered by a (001) LiF surface at 78 K has been obtained for different angles of incidence and different orientations of the crystal. The Debye--Waller factor has been measured leading to a surface Debye temperature theta/sub S/=550 +- 38 K. The corrugated-hard-wall-with-a-well model of Garibaldi et al. [Surf. Sci. 48, 649 (1975)] has been used for the interpretation of the intensities of the diffracted peaks. By means of a best fit procedure we obtain a main ''corrugation'' parameter xi 0 =0.095 A. By comparison of the data with the theory of Cabrera et al. [Surf. Sci. 19, 70 (1967] at the first order, the strength parameters of a periodic Morse potential have been determined

  6. Possible effect of static surface disorder on diffractive scattering of H2 from Ru(0001): Comparison between theory and experiment.

    Science.gov (United States)

    Kroes, G J; Wijzenbroek, Mark; Manson, J R

    2017-12-28

    Specific features of diffractive scattering of H 2 from metal surfaces can serve as fingerprints of the reactivity of the metal towards H 2 , and in principle theory-experiment comparisons for molecular diffraction can help with the validation of semi-empirical functionals fitted to experiments of sticking of H 2 on metals. However, a recent comparison of calculated and Debye-Waller (DW) extrapolated experimental diffraction probabilities, in which the theory was done on the basis of a potential energy surface (PES) accurately describing sticking to Ru(0001), showed substantial discrepancies, with theoretical and experimental probabilities differing by factors of 2 and 3. We demonstrate that assuming a particular amount of random static disorder to be present in the positions of the surface atoms, which can be characterized through a single parameter, removes most of the discrepancies between experiment and theory. Further improvement might be achievable by improving the accuracy of the DW extrapolation, the model of the H 2 rotational state distribution in the experimental beams, and by fine-tuning the PES. However, the question of whether the DW model is applicable to attenuation of diffractive scattering in the presence of a sizable van der Waals well (depth ≈ 50 meV) should also receive attention, in addition to the question of whether the amount of static surface disorder effectively assumed in the modeling by us could have been present in the experiments.

  7. Quantum scattering of neon from a nanotextured surface

    International Nuclear Information System (INIS)

    Levi, A C; Huang, C; Allison, W; MacLaren, D A

    2009-01-01

    Phonon exchange is the usual cause of decoherence in atom-surface scattering. By including quantum effects in the treatment of Debye-Waller scattering, we show that phonon exchange becomes ineffective when the relevant phonon frequencies are high. The result explains the surprising observation of strong elastic scattering of Ne from a Cu(100) surface nanotextured with a c(2 x 2) Li adsorbate structure. We extend a previous model to describe the phonon spectra by an Einstein oscillator component with an admixture of a Debye spectrum. The Einstein oscillator represents the dominant, high frequency vibration of the adsorbate, normal to the surface, while the Debye spectrum represents the substrate contribution. Neon scattering is so slow that exciting the adsorbate mode has a low probability and is impossible if the incident energy is below the threshold. Thus, adsorbate vibrations are averaged out. A theoretical discussion and calculation shows that under such circumstances the vibrations of a light adsorbate do not contribute to the Debye-Waller effect, with the result that Ne scattering at thermal energies is quantum mechanical and largely elastic, explaining the high reflectivity and the diffraction peaks observed experimentally.

  8. Absorptive form factors for high-energy electron diffraction

    International Nuclear Information System (INIS)

    Bird, D.M.; King, Q.A.

    1990-01-01

    The thermal diffuse scattering contribution to the absorptive potential in high-energy electron diffraction is calculated in the form of an absorptive contribution to the atomic form factor. To do this, the Einstein model of lattice vibrations is used, with isotropic Debye-Waller factors. The absorptive form factors are calculated as a function of scattering vector s and temperature factor M on a grid which enables polynomial interpolation of the results to be accurate to better than 2% for much of the ranges 0≤Ms 2 ≤6 and 0≤M≤2 A 2 . The computed values, together with an interpolation routine, have been incorporated into a Fortran subroutine which calculates both the real and absorptive form factors for 54 atomic species. (orig.)

  9. Robust parameterization of elastic and absorptive electron atomic scattering factors

    International Nuclear Information System (INIS)

    Peng, L.M.; Ren, G.; Dudarev, S.L.; Whelan, M.J.

    1996-01-01

    A robust algorithm and computer program have been developed for the parameterization of elastic and absorptive electron atomic scattering factors. The algorithm is based on a combined modified simulated-annealing and least-squares method, and the computer program works well for fitting both elastic and absorptive atomic scattering factors with five Gaussians. As an application of this program, the elastic electron atomic scattering factors have been parameterized for all neutral atoms and for s up to 6 A -1 . Error analysis shows that the present results are considerably more accurate than the previous analytical fits in terms of the mean square value of the deviation between the numerical and fitted scattering factors. Parameterization for absorptive atomic scattering factors has been made for 17 important materials with the zinc blende structure over the temperature range 1 to 1000 K, where appropriate, and for temperature ranges for which accurate Debye-Waller factors are available. For other materials, the parameterization of the absorptive electron atomic scattering factors can be made using the program by supplying the atomic number of the element, the Debye-Waller factor and the acceleration voltage. For ions or when more accurate numerical results for neutral atoms are available, the program can read in the numerical values of the elastic scattering factors and return the parameters for both the elastic and absorptive scattering factors. The computer routines developed have been tested both on computer workstations and desktop PC computers, and will be made freely available via electronic mail or on floppy disk upon request. (orig.)

  10. Theoretical Studies of the Structure and the Dynamics on Clean and Chemisorbed Metal Surfaces

    Science.gov (United States)

    Yang, Liqiu

    ) surfaces, it is concluded that a substrate missing-row type reconstruction is induced by the adsorbates, but the local symmetry is C_{2v} with oxygen atoms at the long-bridge sites for the former and C_{s} with (110) being the only symmetry axis for the latter. In the above theoretical analysis, close contacts are made to many available experimental results such as surface phonon dispersion curves, interlayer relaxations, and Debye -Waller factors and adsorbate-substrate bond lengths.

  11. A summary of the low angle x-ray atomic scattering factors which have been measured by the critical voltage effect in High Energy Electron Diffraction (HEED)

    International Nuclear Information System (INIS)

    Fox, A.G.; Fisher, R.M.

    1987-08-01

    A tabulated summary of all the accurate (/approximately/0.1%) low-angle x-ray atomic scattering (form) factors which have been determined by the systematic critical voltage technique in HEED is presented. For low atomic number elements (Z/approx lt/40) the low angle form factors can be significantly different to best free atom values, and so the best band structure calculated and/or x-ray measured form factors consistent with the critical voltage measurements are also indicated. At intermediate atomic numbers Z≅40→50 only the very low-angle form factors appear to be different to the best free atom values, and even then only by a small amount. For heavy elements (Z/approx lt/70) the best free atom form factors appear to agree very closely with the critical voltage measured values and so, in this case, critical voltage measurements give very accurate measurements of Debye-Waller factors. 48 refs

  12. Theory of inelastic effects in resonant atom-surface scattering

    International Nuclear Information System (INIS)

    Evans, D.K.

    1983-01-01

    The progress of theoretical and experimental developments in atom-surface scattering is briefly reviewed. The formal theory of atom-surface resonant scattering is reviewed and expanded, with both S and T matrix approaches being explained. The two-potential formalism is shown to be useful for dealing with the problem in question. A detailed theory based on the S-matrix and the two-potential formalism is presented. This theory takes account of interactions between the incident atoms and the surface phonons, with resonant effects being displayed explicitly. The Debye-Waller attenuation is also studied. The case in which the atom-surface potential is divided into an attractive part V/sub a/ and a repulsive part V/sub r/ is considered at length. Several techniques are presented for handling the scattering due to V/sub r/, for the case in which V/sub r/ is taken to be the hard corrugated surface potential. The theory is used to calculate the scattered intensities for the system 4 He/LiF(001). A detailed comparison with experiment is made, with polar scans, azimuthal scans, and time-of-flight measurements being considered. The theory is seen to explain the location and signature of resonant features, and to provide reasonable overall agreement with the experimental results

  13. Threshold and Lennard-Jones resonances and elastic lifetimes in the scattering of atoms from crystalline surfaces

    International Nuclear Information System (INIS)

    Garcia, N.

    1978-01-01

    The GR method for solving the scattering equations of atoms from a hard corrugated surface is applied on accelerated particles above a hard corrugated surface and a hard corrugated surface with an attractive well. The solutions are given for the Rayleigh hypothesis that under the range of corrugation presented in this paper leads to the exact ones. Threshold resonances are studied observing that the appearance and disappearance of beams must be for a general theory with vertical tangent. The structure of the Lennard-Jones resonances given for the model mentioned above. For the first time it is stressed that Lennard-Jones resonances are not observed in metal surfaces in general, and, accordingly, they are unobserved in compact metallic surfaces. This is correlated with the fact that diffraction has not been observed. Both facts are due to the very weak corrugation of the gas-metal interaction potential. According to our results, the Lennard-Jones resonances in metals present greater difficulties to be observed experimentally. It is also noted that the absence of diffraction in compact metal surfaces is because they are almost plane and not because of the Debye-Waller effect. Finally, the lifetimes of the atoms at the crystal surfaces are calculated. These are larger, the smaller the incident energy and the larger the corrugation. But the lifetimes are particularly large at resonance conditions (10 -11 s). (Auth.)

  14. Application of the backscattering of an atomic beam of thermal energy to the study of the vibrational properties of metal surfaces

    International Nuclear Information System (INIS)

    Lapujoulade, J.; Lejay, Y.

    1975-01-01

    Vibrational properties of metal surfaces (surface phonons, surface Debye temperatures) are less known than bulk ones since common investigation methods (neutron, X-rays) are not sensitive to surface properties. A study of the backscattering of an atomic beam may give surface specific informations. The backscattering of noble gas (He, Ne, Ar) from a clean copper single crystal ((100) face) was experimentally studied. The experimental set-up allows to measure the space repartition well as the velocity distribution of the scattered atoms. If the collisions is purely elastic an analysis of the thermal dependence of the specular peak by means of the Debye Waller formula will give the mean square displacements of surface atoms. It is shown however that this simple case is not fulfilled with helium in ordinary beam or solid temperatures. If the collision is inelastic, but dominated by single phonon transfers (as it seems to be the case for helium) information should to get about the phonon dispersion relation of surface atoms. When many-phonon collision occur (Ne and Ar) the analysis is more difficult. A comparison of the experimental result with an approximate calculation of G. Armand is given [fr

  15. Ultrafast electron diffraction from non-equilibrium phonons in femtosecond laser heated Au films

    Energy Technology Data Exchange (ETDEWEB)

    Chase, T. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Trigo, M.; Reid, A. H.; Dürr, H. A. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Li, R.; Vecchione, T.; Shen, X.; Weathersby, S.; Coffee, R.; Hartmann, N.; Wang, X. J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Reis, D. A. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

    2016-01-25

    We use ultrafast electron diffraction to detect the temporal evolution of non-equilibrium phonons in femtosecond laser-excited ultrathin single-crystalline gold films. From the time-dependence of the Debye-Waller factor, we extract a 4.7 ps time-constant for the increase in mean-square atomic displacements. The observed increase in the diffuse scattering intensity demonstrates that the energy transfer from laser-heated electrons to phonon modes near the X and K points in the Au fcc Brillouin zone proceeds with timescales of 2.3 and 2.9 ps, respectively, faster than the Debye-Waller average mean-square displacement.

  16. Dynamic Factor Models for the Volatility Surface

    DEFF Research Database (Denmark)

    van der Wel, Michel; Ozturk, Sait R.; Dijk, Dick van

    The implied volatility surface is the collection of volatilities implied by option contracts for different strike prices and time-to-maturity. We study factor models to capture the dynamics of this three-dimensional implied volatility surface. Three model types are considered to examine desirable...

  17. TEMPERATURE DEPENDENCE OF 57Fe-MÖSSBAUER SPECTRA FOR A 〖〖Fe〗_Fc^II-Fe〗_tpy^II-〖Fe〗_Fc^II TRINUCLEAR SYSTEM

    Directory of Open Access Journals (Sweden)

    Dumitru Sirbu

    2015-06-01

    Full Text Available 57Fe Mӧssbauer spectra were recorded for 1'-terpyridine ferrocenecarboxylic acid and [bis(1'-terpyridine ferrocenecarboxylic acid Fe(II]2+ in the temperature range 7 – 293 K. The temperature dependence of the Quadrupole Splitting, Isomer Shift and Debye-Waller factor are discussed. The Debye temperature for the iron nuclei in the investigated compounds was determined.

  18. An investigation of the chromium oxidation state of a monoanionic chromium tris(catecholate) complex by X-ray absorption and EPR spectroscopies

    DEFF Research Database (Denmark)

    Pattison, D I; Levina, A; Davies, Michael Jonathan

    2001-01-01

    The well-known monoanionic Cr tris(3,5-di-tert-butylcatecholato) complex, [Cr(DTBC)3]-, has been studied by X-ray absorption spectroscopy. The multiple-scattering fit to the XAFS gave good correlation (R = 19.8%) and good values for all of the bond lengths, angles, and Debye-Waller factors. The p...

  19. He/Ar-atom scattering from molecular monolayers: C{sub 60}/Pt(111) and graphene/Pt(111)

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Y; Sugawara, C; Satake, Y; Yokoyama, Y; Okada, R; Nakayama, T; Sasaki, M [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki (Japan); Kondo, T; Oh, J; Nakamura, J [Institute of Material Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki (Japan); Hayes, W W [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634 (United States)

    2010-08-04

    Supersonic He and Ar atomic beam scattering from C{sub 60} and graphene monolayers adsorbed on a Pt(111) surface are demonstrated in order to obtain detailed insight into a gas-molecule collision that has not been studied in detail so far. The effective masses and phonon spectral densities of the monolayers seen by different projectiles are discussed based on classical models such as the hard cube model and the recently developed smooth surface model. Large effective masses are deduced for both the monolayers, suggesting collective effects of surface atoms in the single collision event. The effective Debye temperature of graphene was found to be similar to that reported in highly oriented pyrolytic graphite (HOPG), indicating that the graphene is decoupled well from the Pt substrate. A much smaller Debye-Waller factor was found for the C{sub 60} layer, probably reflecting the strong C{sub 60}-Pt(111) interaction.

  20. Ultrafast time-resolved electron diffraction on adsorbate systems on silicon surfaces. Vibrational excitation in monllayers and dynamics of phase transitions; Ultraschnelle zeitaufgeloeste Elektronenbeugung an Adsorbatsystemen auf Siliziumoberflaechen. Vibrationsanregung in Monolagen und Dynamik von Phasenuebergaengen

    Energy Technology Data Exchange (ETDEWEB)

    Moellenbeck, Simone

    2011-04-11

    surface phase transitions was analysed for the first time with TR-RHEED. As a first modell system, the Si(0 0 1) c(4 x 2)-(2 x 1) order disorder phase transition was analyzed. The dynamics of this phase transition can be observed with TR-RHEED, as the Laue rings on which the c(4 x 2)-spots are located vanishes almost completely in the temporal overlap. The observed intensity decrease of the (2 x 1)-reflexes is however quiet small. Due to the direct bandgap of Silicon, a direct absorption of the photons in the Silicon substrate can be excluded. Instead, the excitation of the phase transition is explained by absorption in the surface state of the tilted dimer. Furthermore, the Peierls like phase transition of In/Si(1 1 1) (4 x 1)-(8 x ''2'') was analyzed in detail. This phase transition can be observed excellently in TR-RHEED: the diffraction spots of the (8 x ''2'')-reconstruction vanish whereas the intensity of the (4 x 1)-spots increases simultaneously. The intensity increase cannot be explained with a simple Debye-Waller effect. A real structural transiton at the surface takes place. Fluence and base temperature dependent measurements are presented to confirm, that the electronic excitation instead of thermal excitation destroys the low temperature phase. Furthermore, a complete structural formation of the (8 x ''2'')-reconstruction (time constant of approx. 500 ps) and growth from seeds around adsorbates (down to 50 ps) can be distinguished. In addition, the thermal cooling before the structural change can be observed when the surface is heated above the phase transition temperature (time constant up to 2000 ps). (orig.)

  1. Structural anisotropy in amorphous SnO2 film probed by X-ray absorption spectroscopy

    Science.gov (United States)

    Zhu, Q.; Ma, Q.; Buchholz, D. B.; Chang, R. P. H.; Bedzyk, M. J.; Mason, T. O.

    2013-07-01

    Polarization-dependent X-ray absorption measurements reveal the existence of structural anisotropy in amorphous (a-) SnO2 film. The anisotropy is readily seen for the second neighbor interaction whose magnitude differs along three measured directions. The differences can be well accounted for by 10%-20% variation in the Debye-Waller factor. Instead of a single Gaussian distribution found in crystalline SnO2, the Sn-O bond distribution is bimodal in a-SnO2 whose separation shows a weak angular dependence. The oxygen vacancies, existing in the a-SnO2 film in the order of 1021 cm-3, distribute preferentially along the film surface direction.

  2. New configuration factors for curved surfaces

    International Nuclear Information System (INIS)

    Cabeza-Lainez, Jose M.; Pulido-Arcas, Jesus A.

    2013-01-01

    Curved surfaces have not been thoroughly considered in radiative transfer analysis mainly due to the difficulties arisen in the integration process and perhaps because of the lack of spatial vision of the researchers. It is a fact, especially for architectural lighting, that when concave geometries appear inside a curved space, they are mostly avoided. In this way, a vast repertoire of significant forms is neglected and energy waste is evident. Starting from the properties of volumes enclosed by the minimum number of surfaces, the authors formulate, with little calculus, new simple laws, which enable them to discover a set of configuration factors for caps and various segments of the sphere. The procedure is subsequently extended to previously unimagined surfaces as the paraboloid, the ellipsoid or the cone. Appropriate combination of the said forms with right truncated cones produces several complex volumes, often used in architectural and engineering creations and whose radiative performance could not be accurately predicted for decades. To complete the research, a new method for determining interreflections in curved volumes is also presented. Radiative transfer simulation benefits from these findings, as the simplicity of the results has led the authors to create innovative software more efficient for design and evaluation and applicable to emerging fields like LED lighting. -- Highlights: ► Friendly revision of fundamentals of radiative transfer. ► New configuration factors for curved surfaces obtained without calculus. ► New method for interreflections in curved geometries. ► Enhanced simulation algorithms. ► Fast comparison of radiative performances of surfaces

  3. Surface water quality assessment using factor analysis

    African Journals Online (AJOL)

    2006-01-16

    Jan 16, 2006 ... Surface water, groundwater quality assessment and environ- .... Urbanisation influences the water cycle through changes in flow and water ..... tion of aquatic life, CCME water quality Index 1, 0. User`s ... Water, Air Soil Pollut.

  4. Factors influencing surface roughness of polyimide film

    International Nuclear Information System (INIS)

    Yao Hong; Zhang Zhanwen; Huang Yong; Li Bo; Li Sai

    2011-01-01

    The polyimide (PI) films of pyromellitic dianhydride-oxydiamiline (PMDA-ODA) were fabricated using vapor deposition polymerization (VDP) method under high vacuum pressure of 10-4 Pa level. The influence of equipment, substrate temperature, the process of heating and deposition ratio of monomers on the surface roughness of the PI films was investigated. The surface topography of films was measured by interferometer microscopy and scanning electron microscopy(SEM), and the surface roughness was probed with atomic force microscopy(AFM). The results show that consecutive films can be formed when the distance from steering flow pipe to substrate is 74 cm. The surface roughnesses are 291.2 nm and 61.9 nm respectively for one-step heating process and multi-step heating process, and using fine mesh can effectively avoid the splash of materials. The surface roughness can be 3.3 nm when the deposition rate ratio of PMDA to ODA is 0.9:1, and keeping the temperature of substrate around 30 degree C is advantageous to form a film with planar micro-surface topography. (authors)

  5. Surface sensitivity of nuclear-knock-out form factors

    International Nuclear Information System (INIS)

    Fratamico, G.

    1984-01-01

    A numerical calculation has been performed to investigate the sensitivity of nuclear-knock-out form factors to nuclear-surface behaviour of bound-state wave functions. The result of our investigation suggests that one can extract the bound-state behaviour at the surface from experimental information on nuclear-knock-out form factors

  6. Factors influencing graphene growth on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Loginova, E; Bartelt, N C; McCarty, K F [Sandia National Laboratories, Livermore, CA (United States); Feibelman, P J [Sandia National Laboratories, Albuquerque, NM (United States)], E-mail: mccarty@sandia.gov

    2009-06-15

    Graphene forms from a relatively dense, tightly bound C-adatom gas when elemental C is deposited on or segregates to the Ru(0001) surface. Nonlinearity of the graphene growth rate with C-adatom density suggests that growth proceeds by addition of C atom clusters to the graphene edge. The generality of this picture has now been studied by use of low-energy electron microscopy (LEEM) to observe graphene formation when Ru(0001) and Ir(111) surfaces are exposed to ethylene. The finding that graphene growth velocities and nucleation rates on Ru have precisely the same dependence on adatom concentration as for elemental C deposition implies that hydrocarbon decomposition only affects graphene growth through the rate of adatom formation. For ethylene, that rate decreases with increasing adatom concentration and graphene coverage. Initially, graphene growth on Ir(111) is like that on Ru: the growth velocity is the same nonlinear function of adatom concentration (albeit with much smaller equilibrium adatom concentrations, as we explain with DFT calculations of adatom formation energies). In the later stages of growth, graphene crystals that are rotated relative to the initial nuclei nucleate and grow. The rotated nuclei grow much faster. This difference suggests firstly, that the edge-orientation of the graphene sheets relative to the substrate plays an important role in the growth mechanism, and secondly, that attachment of the clusters to the graphene is the slowest step in cluster addition, rather than formation of clusters on the terraces.

  7. Microscopic view of disorder in the ordered phase of superionic RbAg4I5

    International Nuclear Information System (INIS)

    Pasternak, M.

    1983-01-01

    Moessbauer spectroscopy in 129 I was employed to verify the existence and investigate the properties of local disorder in the ''ordered'' state of the superionic conductor RbAg 4 I 5 . Studies were conducted in the temperature range of 4--180 K covering the low-temperature #betta# phase (T 129 I nucleus, produced by the neighboring Ag ions, has a continuous linear temperature dependence down to 4.2 K. The hyperfine constants and the Debye-Waller factor showed no discontinuity at T/sub c/. The anomalous existence of the single line has been attributed to a fast fluctuating efg due to local hopping of the Ag ions. This dynamic disorder is present even at low temperatures where (8--10)% of Ag ions are locally hopping, and its occurrence increases drastically at T>T/sub c/. A nonharmonic Debye-Waller factor was observed from which a linear temperature-dependent Debye temperature could be derived

  8. Weak coupling theory of the ripplon limited mobility of a 2-D electron lattice

    International Nuclear Information System (INIS)

    Dahm, A.J.; Mehrotra, R.

    1981-01-01

    The one ripplon-n phonon scattering contribution to the mobility of a 2D electron lattice supported by a liquid helium substrate is calculated in first order perturbation theory to all orders of n in the weak coupling limit. The Debye Waller factor is shown to limit the momentum transfer at large ripplon wave-vectors and high temperatures causing a minimum in the mobility as a function of temperature. (orig.)

  9. Contrast of HOLZ lines in energy-filtered convergent-beam electron diffraction patterns from silicon

    International Nuclear Information System (INIS)

    Lehmpfuhl, G.; Krahl, D.; Uchida, Y.

    1995-01-01

    Higher-order Laue-zone (HOLZ) lines were investigated in convergent-beam electron diffraction patterns from silicon near the low-indexed zone axes [100], [110] and [111]. The visibility of these lines depends on the effective structure potentials of the reflections from the first Laue zone depending on their Debye-Waller factor. The contrast of the HOLZ lines is strongly reduced by inelastically scattered electrons. They can be excluded by an imaging Ω filter for energy losses above 2 eV. The diffraction patterns were compared with many-beam calculations. Without absorption, an excellent agreement could be achieved for the [111] and [100] zone axes, while the simulation of the [110] zone-axis pattern needed a calculation with absorption. The reason for this observation is explained in the Bloch-wave picture. Calculations with absorption, however, lead to artefacts in the intensity distribution of the [100] HOLZ pattern. In order to obtain agreement with the experiment, the Debye-Waller factor had to be modified in different ways for the different zone axes. This corresponds to a strong anisotropy of the Debye-Waller factor. To confirm this observation, the temperature dependence of the itensity distributions of the HOLZ patterns was investigated between 50 and 680 K. At room temperature, the parameter D in the Debye-Waller factor exp(-Ds 2 ) was determined as 0.13, 0.26 and 0.55 A 2 for the zone axes [100], [111] and [110], respectively. The reliability of the conclusions is discussed. (orig.)

  10. 100KE/KW fuel storage basin surface volumetric factors

    International Nuclear Information System (INIS)

    Conn, K.R.

    1996-01-01

    This Supporting Document presents calculations of surface Volumetric factors for the 100KE and 100KW Fuel Storage Basins. These factors relate water level changes to basin loss or additions of water, or the equivalent water displacement volumes of objects added to or removed from the basin

  11. Influencing factors on the visibility of surface distresses

    Science.gov (United States)

    Smęt, Wojciech; Skakuj, Marek

    2018-05-01

    A systematic and future-oriented maintenance management requires quality-assured data regarding the condition of the roadway. An important characteristic for assessing the condition of the road surface are cracks [1]. Experience has proven that the road surface temperature and residual humidity can influence the visibility of cracks. To investigate and quantify these influencing factors in more detail, the Federal Ministry of Transport and Digital Infrastructure has implemented a comprehensive research project [2], during which several measurement campaigns were carried out at different seasons and at different temperatures and humidity degrees of the road surface. The visibility of the cracks was assessed using the German approach ZTV ZEB-StB [3]. After evaluating the cracks, the data was synchronized and the network allocation of the geo-referenced raw data was realized. The relevant condition performance indicators were calculated subsequently. For each evaluation section of 100 meters length, the mean road surface temperature was calculated and, if available, the type and year of construction of the surface course was determined. The evaluated data was visualized to establish correlations between the data and the influencing factors. For the statistical analysis of the results, a total of six comparative scenarios were defined in which the influencing factors of road surface temperature and residual humidity were assessed. This paper documents the results of the research project. In order to obtain a uniform and comparable picture of the condition of the road surface over the years and thus to be able to observe the aging process of the road surface, the measurement campaigns are to be carried out under defined conditions. The research project included proposals for defining and further specifying the measurement conditions.

  12. Topography measurements for determining the decay factors in surface replication

    International Nuclear Information System (INIS)

    Song, J; Zheng, A; Vorburger, T V; Rubert, P

    2008-01-01

    The electro-forming technique is used at National Institute of Standards and Technology (NIST) for the production of standard reference material (SRM) 2461 standard casings to support nationwide ballistics measurement traceability and measurement quality control in the US. In order to ensure that the SRM casings are produced with virtually the same surface topography, it is necessary to test the decay factors of the replication process. Twenty-six replica casings are replicated from the same master casing for the decay factor tests. The NIST topography measurement system is used for measurements and correlations of surface topography. The topography decays are quantified by the cross-correlation function maximum CCF max . Based on the test, it is expected that 256 SRM casings can be replicated from the same master with CCF max values higher than 95%

  13. Calculation of Operations Efficiency Factors for Mars Surface Missions

    Science.gov (United States)

    Layback, Sharon L.

    2014-01-01

    For planning of Mars surface missions, to be operated on a sol-by-sol basis by a team on Earth (where a "sol" is a Martian day), activities are described in terms of "sol types" that are strung together to build a surface mission scenario. Some sol types require ground decisions based on a previous sol's results to feed into the activity planning ("ground in the loop"), while others do not. Due to the differences in duration between Earth days and Mars sols, for a given Mars local solar time, the corresponding Earth time "walks" relative to the corresponding times on the prior sol/day. In particular, even if a communication window has a fixed Mars local solar time, the Earth time for that window will be approximately 40 minutes later each succeeding day. Further complexity is added for non-Mars synchronous communication relay assets, and when there are multiple control centers in different Earth time zones. The solution is the development of "ops efficiency factors" that reflect the efficiency of a given operations configuration (how many and location of control centers, types of communication windows, synchronous or non-synchronous nature of relay assets, sol types, more-or-less sustainable operations schedule choices) against a theoretical "optimal" operations configuration for the mission being studied. These factors are then incorporated into scenario models in order to determine the surface duration (and therefore minimum spacecraft surface lifetime) required to fulfill scenario objectives. The resulting model is used to perform "what-if" analyses for variations in scenario objectives. The ops efficiency factor is the ratio of the figure of merit for a given operations factor to the figure of merit for the theoretical optimal configuration. The current implementation is a pair of models in Excel. The first represents a ground operations schedule for 500 sols in each operations configuration for the mission being studied (500 sols was chosen as being a long

  14. Calculation of Operations Efficiency Factors for Mars Surface Missions

    Science.gov (United States)

    Laubach, Sharon

    2014-01-01

    The duration of a mission--and subsequently, the minimum spacecraft lifetime--is a key component in designing the capabilities of a spacecraft during mission formulation. However, determining the duration is not simply a function of how long it will take the spacecraft to execute the activities needed to achieve mission objectives. Instead, the effects of the interaction between the spacecraft and ground operators must also be taken into account. This paper describes a method, using "operations efficiency factors", to account for these effects for Mars surface missions. Typically, this level of analysis has not been performed until much later in the mission development cycle, and has not been able to influence mission or spacecraft design. Further, the notion of moving to sustainable operations during Prime Mission--and the effect that change would have on operations productivity and mission objective choices--has not been encountered until the most recent rover missions (MSL, the (now-cancelled) joint NASA-ESA 2018 Mars rover, and the proposed rover for Mars 2020). Since MSL had a single control center and sun-synchronous relay assets (like MER), estimates of productivity derived from MER prime and extended missions were used. However, Mars 2018's anticipated complexity (there would have been control centers in California and Italy, and a non-sun-synchronous relay asset) required the development of an explicit model of operations efficiency that could handle these complexities. In the case of the proposed Mars 2018 mission, the model was employed to assess the mission return of competing operations concepts, and as an input to component lifetime requirements. In this paper we provide examples of how to calculate the operations efficiency factor for a given operational configuration, and how to apply the factors to surface mission scenarios. This model can be applied to future missions to enable early effective trades between operations design, science mission

  15. Structure of a Rh/TiO2 catalyst in the strong metal-support interaction state as determined by EXAFS

    International Nuclear Information System (INIS)

    Koningsberger, D.C.; Martens, J.H.A.; Prins, R.; Short, D.R.; Sayers, D.E.

    1986-01-01

    Reduction of a highly dispersed 2.85 wt% Rh/TiO 2 catalyst at 473 K after previous calcination at 623 K resulted in EXAFS whose primary contributions are due to nearest rhodium (average coordination number of 3.1 and distance of 2.67 A) and oxygen neighbors (coordination 2.5 and distance 2.71 A). These oxygen neighbors originated at the metal-support interface. The average rhodium-rhodium coordination number did not change in the SMSI state produced by reducing the catalyst at 673 K. However, the average coordination distance contracted by 0.04 A with an accompanying decrease of the Debye-Waller factor of the Rh-Rh bond of 0.0012 A 2 . This is due to the fact that in the SMSI state the surface of the metal particles is not covered with chemisorbed hydrogen. The SMSI state leads to a structural reorganization of the support in the vicinity of the rhodium metal particles. This can be concluded from the appearance of a Rh-Ti bond at 3.42 A in the SMSI state coupled with the fact that the average coordination number of the rhodium-support oxygen bonds does not increase. Other types of rhodium-oxygen bonds could not be detected with EXAFS in this state. Thus, these results provide no evidence for coverage of the metal particle by a suboxide of TiO 2 in the SMSI state

  16. Plasticization effect of C60 on the fast dynamics of polystyrene and related polymers: an incoherent neutron scattering study

    International Nuclear Information System (INIS)

    Sanz, Alejandro; Ruppel, Markus; Cabral, Joao T; Douglas, Jack F

    2008-01-01

    We utilize inelastic incoherent neutron scattering (INS) to quantify how fullerenes affect the 'fast' molecular dynamics of a family of polystyrene related macromolecules. In particular, we prepared bulk nanocomposites of (hydrogenous and ring-deuterated) polystyrene and poly(4-methyl styrene) using a rapid precipitation method where the C 60 relative mass fraction ranged from 0% to 4%. Elastic window scan measurements, using a high resolution (0.9 μeV) backscattering spectrometer, are reported over a wide temperature range (2-450 K). Apparent Debye-Waller (DW) factors 2 >, characterizing the mean-square amplitude of proton displacements, are determined as a function of temperature, T. We find that the addition of C 60 to these polymers leads to a progressive increase in 2 > relative to the pure polymer value over the entire temperature range investigated, where the effect is larger for larger nanoparticle concentration. This general trend seems to indicate that the C 60 nanoparticles plasticize the fast (∼10 -15 s) local (∼1 A) dynamics of these polymer glasses. Generally, we expect nanoparticle additives to affect polymer dynamics in a similar fashion to thin films in the sense that the high interfacial area may cause both a speeding up and slowing down of the glass state dynamics depending on the polymer-surface interaction

  17. Factors influencing the surface quality of polished tool steels

    International Nuclear Information System (INIS)

    Rebeggiani, S; Rosén, B-G

    2014-01-01

    Today’s demands on surface quality of moulds for injection moulding of plastic components involve no/low defect contents and roughness levels in the nm-range for high gloss applications. Material properties as well as operating conditions influence the mould finish, and thus the final surface of moulded products. This paper focuses on how particle content and different polishing strategies influence final surface qualities of moulds. Visual estimations of polished tool steel samples were combined with non-contact 3D-surface texture analysis in order to correlate traditional assessments to more quantitative methods, and to be able to analyse the surfaces at nanometre-level. It was found that steels with a lower proportion of particles, like carbides and oxides, gave rise to smoother polished surfaces. In a comparative study of polishers from different polishing shops, it was found that while different surface preparation strategies can lead to similar final roughness, similar preparation techniques can produce high-quality surfaces from different steel grades. However, the non-contact 3D-surface texture analysis showed that not all smooth polished surfaces have desirable functional topographies for injection moulding of glossy plastic components. (paper)

  18. Dynamic Chemical and Structural Changes of Heterogeneous Catalysts Observed in Real Time: From Catalysis-Induced Fluxionality to Catalytic Cycles

    Science.gov (United States)

    2014-11-26

    obtained from the fit of the “Clean Pd NCs” (Figure 5 and Table 1) under the approximation the surface atoms have a bond length and EXAFS Debye -Waller...evidence for a model in which Ar drives restructuring of under-coordinated Pd atoms, leading to an increased Pd-Pd bond length of surface Pd atoms... length expansion was calculated by taking the difference between the average NN bond length of each atom before and after being exposed to Ar. The

  19. Neutron scattering by anharmonic crystals and the effect of sublattice displacements

    International Nuclear Information System (INIS)

    Viswanathan, K.S.; Phillip, Jacob

    1979-01-01

    A theory has been described for the scattering of neutrons by anharmonic crystals, for which terms of the type Vsup(3) (k 1 j 1 ;-k 1 j 1 ;aj) which contribute to the sublattice displacements are not neglected. It is shown that the sublattice displacements will modify the phase factor arising from the scattering by any atom in the unit cell, and the Debye-Waller factor also gets altered both by the sublattice displacements as well as by higher order terms arising from anharmonicity. (author)

  20. Convergence of the multiple scattering expansion in XAFS and XANES

    International Nuclear Information System (INIS)

    Rehr, J.J.

    1992-01-01

    The convergence of the multiple-scattering expansion of XAFS and XANES by explicit path-bypath calculations. The approach is based on the fast scattering matrix formalism of Rehr and Albers, together with an automated path finder and filters that exclude negligible paths. High-order scattering terms are found to be essential, especially at low energies. Several factors including the magnitude of curved wave scattering amplitudes, inelastic losses and multiple-scattering Debye-Waller factors control convergence of the expansion. The convergence is illustrated explicitly for the case of diatomic molecules

  1. A contribution to the investigation of the properties of the Au-Fe system

    International Nuclear Information System (INIS)

    Vano, M.; Sitek, J.; Cirak, J.

    1976-01-01

    Moessbauer spectroscopy, an electronic microanalyzer and X-ray diffractometry were used to study the properties of an Au-Fe solid solution during its preparation by installing Fe atoms into the Au matrix by diffusion heating at a temperature from 550 to 850 degC. On the basis of such measurements, the suitable heating temperature was determined at 850 degC; the Debye-Waller factor for Au-Fe is f=0.604+-0.040 and two configurations of Fe atoms in the Au crystal lattice were found. (author)

  2. Diffusion of Hydrogen in the beta-Phase of Pd-H Studied by Small Energy Transfer Neutron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Nelin, G; Skoeld, K

    1974-07-01

    The diffusion of hydrogen in beta-PdH has been studied by quasielastic neutron scattering. It is shown that the diffusion occurs through jumps between adjacent octahedral interstitial sites. The observed integrated quasielastic intensities cannot be described by a simple Debye-Waller factor. The phase transition from the beta-phase to the alpha-phase has also been studied. No dramatic changes in the scattering patterns were observed. It is concluded that the diffusion mechanism is remarkably similar between the low concentration alpha-phase and the high concentration beta-phase

  3. Mosaic crystal algorithm for Monte Carlo simulations

    CERN Document Server

    Seeger, P A

    2002-01-01

    An algorithm is presented for calculating reflectivity, absorption, and scattering of mosaic crystals in Monte Carlo simulations of neutron instruments. The algorithm uses multi-step transport through the crystal with an exact solution of the Darwin equations at each step. It relies on the kinematical model for Bragg reflection (with parameters adjusted to reproduce experimental data). For computation of thermal effects (the Debye-Waller factor and coherent inelastic scattering), an expansion of the Debye integral as a rapidly converging series of exponential terms is also presented. Any crystal geometry and plane orientation may be treated. The algorithm has been incorporated into the neutron instrument simulation package NISP. (orig.)

  4. Defects and disorder in the fast-ion electrode lithium-aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Susman, S; Brun, T O

    1981-01-01

    Neutron and X-ray diffraction measurements indicate no phase change in ..beta..-phase LiAl from 300 to 940 K. The thermal expansion of the lattice constant and the temperature dependence of the Debye-Waller factor Li are linear and not unusually large. The data are analyzed in the Bragg-Williams approximation with T/sub c/ = 1100 K. At elevated temperatures, LiAl approaches an order-disorder transformation. At battery operating temperatures (700 K) there are appreciable concentrations of both types of antisite defects Li/sub Al/ and Al/sub Li/, and there is appreciable Al diffusion.

  5. Co-Au core-shell nanocrystals formed by sequential ion implantation into SiO2

    International Nuclear Information System (INIS)

    Kluth, P.; Hoy, B.; Johannessen, B.; Dunn, S. G.; Foran, G. J.; Ridgway, M. C.

    2006-01-01

    Co-Au core-shell nanocrystals (NCs) were formed by sequential ion implantation of Au and Co into thin SiO 2 . The NCs were investigated by means of transmission electron microscopy and extended x-ray absorption fine structure spectroscopy. The latter reveals a bond length expansion in the Co core compared to monatomic Co NCs. Concomitantly, a significant contraction of the bond length and a significant reduction of the effective Au-Au coordination number were observed in the Au shells. Increased Debye-Waller factors indicate significant strain in the NCs. These experimental results verify recent theoretical predictions

  6. Low temperature anomalies in the lattice parameters of rare earth compounds and UPd3

    International Nuclear Information System (INIS)

    Pluemacher, D.

    1980-01-01

    Using a low temperature diffractometer, intermediate valence effects and crystal defects can be identified from the temperature dependence of the lattice parameters and the Debye-Waller factor. For polycrystalline powder samples the measuring error are too large. For intermediate valence systems the relative change in the 4f-level population probability can be calculated together with the anisotropic effects on the lattice parameters and on the unit cell colume. Pronounced effects on the lattice parameters can be observed in the case of RE Cu 2 Si 2 compounds with crystal fields. (DG) [de

  7. Quality factor due to roughness scattering of shear horizontal surface acoustic waves in nanoresonators

    NARCIS (Netherlands)

    Palasantzas, G.

    2008-01-01

    In this work we study the quality factor associated with dissipation due to scattering of shear horizontal surface acoustic waves by random self-affine roughness. It is shown that the quality factor is strongly influenced by both the surface roughness exponent H and the roughness amplitude w to

  8. Determining eyeball surface area directly exposed to the effects of external factors.

    Science.gov (United States)

    Juliszewski, Tadeusz; Kadłuczka, Filip; Kiełbasa, Paweł

    2016-01-01

    This article discusses determining the surface area of eyeballs of men and women exposed to the direct effects of external factors in the working environment. For one eye, the mean surface is 172-182 mm(2). The determined surface area can be used in formulas for calculating the exposure of eyeballs to harmful chemical substances in workplace air.

  9. Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model

    Science.gov (United States)

    Patricia L. Andrews

    2012-01-01

    Rothermel's surface fire spread model was developed to use a value for the wind speed that affects surface fire, called midflame wind speed. Models have been developed to adjust 20-ft wind speed to midflame wind speed for sheltered and unsheltered surface fuel. In this report, Wind Adjustment Factor (WAF) model equations are given, and the BehavePlus fire modeling...

  10. Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

    KAUST Repository

    Kong, Desheng

    2011-06-28

    Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi2Se3 by transport measurements. © 2011 American Chemical Society.

  11. Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

    KAUST Repository

    Kong, Desheng; Cha, Judy J.; Lai, Keji; Peng, Hailin; Analytis, James G.; Meister, Stefan; Chen, Yulin; Zhang, Hai-Jun; Fisher, Ian R.; Shen, Zhi-Xun; Cui, Yi

    2011-01-01

    Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from

  12. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    Directory of Open Access Journals (Sweden)

    Senai YALCINKAYA

    2017-05-01

    Full Text Available Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the shear rate in step 3 on the friction force was investigated. At the last stage, the experimental study of the effect of the material selection on the friction force was made and it was seen that the aluminum / brass surface pair had the smallest friction coefficient as a result of the opening. The greatest coefficient of friction is found in the pair of glass / felt objects.

  13. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    OpenAIRE

    Senai YALCINKAYA

    2017-01-01

    Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the s...

  14. Factors Affecting Optimal Surface Roughness of AISI 4140 Steel in Turning Operation Using Taguchi Experiment

    Science.gov (United States)

    Novareza, O.; Sulistiyarini, D. H.; Wiradmoko, R.

    2018-02-01

    This paper presents the result of using Taguchi method in turning process of medium carbon steel of AISI 4140. The primary concern is to find the optimal surface roughness after turning process. The taguchi method is used to get a combination of factors and factor levels in order to get the optimum surface roughness level. Four important factors with three levels were used in experiment based on Taguchi method. A number of 27 experiments were carried out during the research and analysed using analysis of variance (ANOVA) method. The result of surface finish was determined in Ra type surface roughness. The depth of cut was found to be the most important factors for reducing the surface roughness of AISI 4140 steel. On the contrary, the other important factors i.e. spindle speed and rake side angle of the tool were proven to be less factors that affecting the surface finish. It is interesting to see the effect of coolant composition that gained the second important factors to reduce the roughness. It may need further research to explain this result.

  15. Experimental analysis on removal factor of smear method in measurement of surface contamination

    International Nuclear Information System (INIS)

    Sugiura, Nobuyuki; Taira, Junichi; Takenaka, Keisuke; Yamanaka, Kazuo; Sugai, Kenji; Kosako, Toshiso

    2007-01-01

    The smear test is one of the important ways to measure surface contamination. The loose contamination under the high background radiation, which is more significant in handling non-sealed radioisotopes, can be evaluated by this method. The removal factor is defined as the ratio of the activity removed from the surface by one smear to the whole activity of the removable surface contamination. The removal factor is greatly changed by the quality and condition of surface materials. In this study, the values of removal factor at several typical surface conditions were evaluated experimentally and the practical application of those values was considered. It is required the smear should be pressed by moderate pressure when wiping the surface. The pressure from 1.0 kg to 1.5 kg per filter paper was recommended. The removal factor showed lower value in wiping by the pressure below 1.0 kg. The value of 0.5 for the removal factor could be applied to the smooth surface of linoleum, concrete coated with paint or epoxy resin, stainless steel and glass with the statistical allowance. (author)

  16. Synchronous scattering and diffraction from gold nanotextured surfaces with structure factors

    Science.gov (United States)

    Gu, Min-Jhong; Lee, Ming-Tsang; Huang, Chien-Hsun; Wu, Chi-Chun; Chen, Yu-Bin

    2018-05-01

    Synchronous scattering and diffraction were demonstrated using reflectance from gold nanotextured surfaces at oblique (θi = 15° and 60°) incidence of wavelength λ = 405 nm. Two samples of unique auto-correlation functions were cost-effectively fabricated. Multiple structure factors of their profiles were confirmed with Fourier expansions. Bi-directional reflectance function (BRDF) from these samples provided experimental proofs. On the other hand, standard deviation of height and unique auto-correlation function of each sample were used to generate surfaces numerically. Comparing their BRDF with those of totally random rough surfaces further suggested that structure factors in profile could reduce specular reflection more than totally random roughness.

  17. Radiation exchange factors between specular inner surfaces of a rectangular enclosure such as transplant production unit

    International Nuclear Information System (INIS)

    Abdel-Ghany, Ahmed M.; Kozai, Toyoki

    2006-01-01

    General mathematical relations are presented for the specular exchange factors, F S , of diffuse radiation exchange between the inner surfaces of a rectangular enclosure. Three of these surfaces are specular reflectors, diffuse emitters and the fourth surface is a diffuse reflector, diffuse emitter. This enclosure can be used as a transplant production unit with artificial lighting for electric energy saving purposes. An image system and the crossed string method are used to derive these relations. The resulting expressions are conceptually simple and similar to the commonly known expressions of the exchange factors between diffuse surfaces, F. The accuracy of the presented F S relations was examined for different numbers of multiple reflections, N, on the specular surfaces and for different aspect ratios (ratio of the width, w to the height, h). The results proved that the relations are accurate and strongly satisfy the well-known relation of the radiation exchange between enclosure surfaces and satisfy the reciprocity relation. For any aspect ratio, considering N of 150 between highly reflective surfaces (ρ = 0.99) is sufficient to estimate the F S factors without any possible error. Using specular reflecting surfaces in such cases significantly reduces the electric energy consumption used for lighting

  18. Immobilization of epidermal growth factor on titanium and stainless steel surfaces via dopamine treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jeonghwa [Nano Medical Engineering Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Tokyo, 192-0397 Japan (Japan); Sakuragi, Makoto; Shibata, Aya; Abe, Hiroshi; Kitajima, Takashi; Tada, Seiichi [Nano Medical Engineering Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Mizutani, Masayoshi; Ohmori, Hitoshi [Material Fabrication Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Ayame, Hirohito [Diagnostic Biochip Laboratory, RIKEN Center for Intellectual Property Strategies, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Son, Tae Il [Bioscience and Biotechnology, Chung-Ang University, 40-1 San, Nae-Ri, Daeduck-myun, Ansung-si, Kyungki-do, 456-756 (Korea, Republic of); Aigaki, Toshiro [Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Tokyo, 192-0397 Japan (Japan); Ito, Yoshihiro, E-mail: y-ito@riken.jp [Nano Medical Engineering Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Tokyo, 192-0397 Japan (Japan); Diagnostic Biochip Laboratory, RIKEN Center for Intellectual Property Strategies, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan)

    2012-12-01

    Titanium and stainless steel were modified with dopamine for the immobilization of biomolecules, epidermal growth factor (EGF). First, the treatment of metal surfaces with a dopamine solution under different pH conditions was investigated. At higher pH, the dopamine solution turned brown and formed precipitates. Treatment of the metals with dopamine at pH 8.5 also resulted in the development of brown color at the surface of the metals. The hydrophobicity of the surfaces increased after treatment with dopamine, independently of pH. X-ray photoelectron spectroscopy revealed the formation of a significant amount of an organic layer on both surfaces at pH 8.5. According to ellipsometry measurements, the organic layer formed at pH 8.5 was about 1000 times as thick as that formed at pH 4.5. The amount of amino groups in the layer formed at pH 8.5 was also higher than that observed in the layer formed at pH 4.5. EGF molecules were immobilized onto the dopamine-treated surfaces via a coupling reaction using carbodiimide. A greater amount of EGF was immobilized on surfaces treated at pH 8.5 compared with pH 4.5. Significantly higher growth of rat fibroblast cells was observed on the two EGF-immobilized surfaces compared with non-immobilized surfaces in the presence of EGF. The present study demonstrated that metals can become bioactive via the surface immobilization of a growth factor and that the effect of the immobilized growth factor on metals was greater than that of soluble growth factor. - Highlights: Black-Right-Pointing-Pointer Epidermal growth factor was covalently immobilized on titan or stainless steel surfaces. Black-Right-Pointing-Pointer Amino groups were formed on the surfaces by the treatment and the growth factor was immobilized through amide bonds. Black-Right-Pointing-Pointer The immobilized epidermal growth factor accelerated cell proliferation more than soluble ones on the surfaces.

  19. Stress intensity factor analyses of surface cracks in three-dimensional structures

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Shibata, Katsuyuki; Watanabe, Takayuki; Tagata, Kazunori.

    1983-11-01

    The stress intensity factor analyses of surface cracks in various three-dimensional structures were performed using the finite element computer program EPAS-J1. The results obtained by EPAS-J1 were compared with other finite element solutions or results obtained by the simplified estimation methods. Among the simplified estimation methods, the equations proposed by Newman and Raju give the distributions of the stress intensity factor along a crack front, which were compared with the result obtained by EPAS-J1. It was confirmed by comparing the results that EPAS-J1 gives reasonable stress intensity factors of surface cracks in three-dimensional structures. (author)

  20. Multiscale weighted colored graphs for protein flexibility and rigidity analysis

    Science.gov (United States)

    Bramer, David; Wei, Guo-Wei

    2018-02-01

    Protein structural fluctuation, measured by Debye-Waller factors or B-factors, is known to correlate to protein flexibility and function. A variety of methods has been developed for protein Debye-Waller factor prediction and related applications to domain separation, docking pose ranking, entropy calculation, hinge detection, stability analysis, etc. Nevertheless, none of the current methodologies are able to deliver an accuracy of 0.7 in terms of the Pearson correlation coefficients averaged over a large set of proteins. In this work, we introduce a paradigm-shifting geometric graph model, multiscale weighted colored graph (MWCG), to provide a new generation of computational algorithms to significantly change the current status of protein structural fluctuation analysis. Our MWCG model divides a protein graph into multiple subgraphs based on interaction types between graph nodes and represents the protein rigidity by generalized centralities of subgraphs. MWCGs not only predict the B-factors of protein residues but also accurately analyze the flexibility of all atoms in a protein. The MWCG model is validated over a number of protein test sets and compared with many standard methods. An extensive numerical study indicates that the proposed MWCG offers an accuracy of over 0.8 and thus provides perhaps the first reliable method for estimating protein flexibility and B-factors. It also simultaneously predicts all-atom flexibility in a molecule.

  1. The dependence of the nuclear charge form factor on short range correlations and surface fluctuation effects

    International Nuclear Information System (INIS)

    Massen, S. E.; Garistov, V. P.; Grypeos, M. E.

    1996-01-01

    The effects of nuclear surface fluctuations on harmonic oscillator elastic charge form factor of light nuclei are investigated, simultaneously approximating the short-range correlations through a Jastrow correlation factor. Inclusion of the surface fluctuation effects within this description, by truncating the cluster expansion at the two-body part, is found to improve somewhat the fit to the elastic charge form-factor of 16 O and 40 Ca. However, the convergence of the cluster expansion is expected to deteriorate. An additional finding is that surface-fluctuation correlations produce a drastic change in the asymptotic behaviour of the point-proton form-factor, which now falls off quite slowly (i.e. as const.q -4 ) at large values of the momentum transfer q

  2. Refined toric branes, surface operators and factorization of generalized Macdonald polynomials

    Science.gov (United States)

    Zenkevich, Yegor

    2017-09-01

    We find new universal factorization identities for generalized Macdonald polynomials on the topological locus. We prove the identities (which include all previously known forumlas of this kind) using factorization identities for matrix model averages, which are themselves consequences of Ding-Iohara-Miki constraints. Factorized expressions for generalized Macdonald polynomials are identified with refined topological string amplitudes containing a toric brane on an intermediate preferred leg, surface operators in gauge theory and certain degenerate CFT vertex operators.

  3. SU-E-T-577: Obliquity Factor and Surface Dose in Proton Beam Therapy

    International Nuclear Information System (INIS)

    Das, I; Andersen, A; Coutinho, L

    2015-01-01

    Purpose: The advantage of lower skin dose in proton beam may be diminished creating radiation related sequalae usually seen with photon and electron beams. This study evaluates the surface dose as a complex function of beam parameters but more importantly the effect of beam angle. Methods: Surface dose in proton beam depends on the beam energy, source to surface distance, the air gap between snout and surface, field size, material thickness in front of surface, atomic number of the medium, beam angle and type of nozzle (ie double scattering, (DS), uniform scanning (US) or pencil beam scanning (PBS). Obliquity factor (OF) is defined as ratio of surface dose in 0° to beam angle Θ. Measurements were made in water phantom at various beam angles using very small microdiamond that has shown favorable beam characteristics for high, medium and low proton energy. Depth dose measurements were performed in the central axis of the beam in each respective gantry angle. Results: It is observed that surface dose is energy dependent but more predominantly on the SOBP. It is found that as SSD increases, surface dose decreases. In general, SSD, and air gap has limited impact in clinical proton range. High energy has higher surface dose and so the beam angle. The OF rises with beam angle. Compared to OF of 1.0 at 0° beam angle, the value is 1.5, 1.6, 1,7 for small, medium and large range respectively for 60 degree angle. Conclusion: It is advised that just like range and SOBP, surface dose should be clearly understood and a method to reduce the surface dose should be employed. Obliquity factor is a critical parameter that should be accounted in proton beam therapy and a perpendicular beam should be used to reduce surface dose

  4. Calculated dose factors for the radiosensitive tissues in bone irradiated by surface-deposited radionuclides

    International Nuclear Information System (INIS)

    Spiers, F.W.; Whitwell, J.R.; Beddoe, A.H.

    1978-01-01

    The method of calculating dose factors for the haemopoietic marrow and endosteal tissues in human trabecular bone, used by Whitwell and Spiers for volume-seeking radionuclides, has been developed for the case of radionuclides which are deposited as very thin layers on bone surfaces. The Monte Carlo method is again used, but modifications to the computer program are made to allow for a surface rather than a volume source of particle emission. The principal change is the introduction of a surface-orientation factor which is shown to have a value of approximately 2, varying slightly with bone structure. Results are given for β-emitting radionuclides ranging from 171 Tm(anti Esub(β) = 0.025 MeV) to 90 Y(anti Esub(β) = 0.93 MeV), and also for the α-emitter 239 Pu. It is shown that where the particle ranges are short compared with the dimensions of the bone structures the dose factors for the surface seekers are much greater than those for the volume seekers. For long range particles the dose factors for surface- and volume-seeking radionuclides converge. Comparisons are given relating the dose factors calculated in this paper on the basis of measured bone structures to those of other workers based on single plane geometry. (author)

  5. Modification of the ASME code z-factor for circumferential surface crack in nuclear ferritic pipings

    International Nuclear Information System (INIS)

    Choi, Young Hwan; Chung, Yon Ki; Koh, Wan Young; Lee, Joung Bae

    1996-01-01

    The purpose of this paper is to modify the ASME Code Z-Factor, which is used in the evaluation of circumferential surface crack in nuclear ferritic pipings. The ASME Code Z-Factor is a load multiplier to compensate plastic load with elasto-plastic load. The current ASME Code Z-Factor underestimates pipe maximum load. In this study, the original SC. TNP method is modified first because the original SC. TNP method has a problem that the maximum allowable load predicted from the original SC. TNP method is slightly higher than that measured from the experiment. Then the new Z-Factor is developed using the modified SC. TNP method. The desirability of both the modified SC. TNP method and the new Z-Factor is examined using the experimental results for the circumferential surface crack in pipings. The results show that (1) the modified SC. TNP method is good for predicting the circumferential surface crack behavior in pipings, and (2) the Z-Factor obtained from the modified SC. TNP method well predicts the behavior of circumferential surface crack in ferritic pipings. 30 refs., 13 figs., 4 tabs. (author)

  6. Growth factor delivery: How surface interactions modulate release in vitro and in vivo

    Science.gov (United States)

    King, William J.; Krebsbach, Paul H.

    2013-01-01

    Biomaterial scaffolds have been extensively used to deliver growth factors to induce new bone formation. The pharmacokinetics of growth factor delivery has been a critical regulator of their clinical success. This review will focus on the surface interactions that control the non-covalent incorporation of growth factors into scaffolds and the mechanisms that control growth factor release from clinically relevant biomaterials. We will focus on the delivery of recombinant human bone morphogenetic protein-2 from materials currently used in the clinical practice, but also suggest how general mechanisms that control growth factor incorporation and release delineated with this growth factor could extend to other systems. A better understanding of the changing mechanisms that control growth factor release during the different stages of preclinical development could instruct the development of future scaffolds for currently untreatable injuries and diseases. PMID:22433783

  7. Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity

    Science.gov (United States)

    Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia

    2016-08-01

    The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.

  8. The glycoprotein Ib-IX-V complex contributes to tissue factor-independent thrombin generation by recombinant factor VIIa on the activated platelet surface

    NARCIS (Netherlands)

    Weeterings, Cees; de Groot, Philip G.; Adelmeijer, Jelle; Lisman, Ton

    2008-01-01

    Several lines of evidence suggest that recombinant factor VIIa (rFVIIa) is able to activate factor X on an activated platelet, in a tissue factor-independent manner. We hypothesized that, besides the anionic surface, a receptor on the activated platelet surface is involved in this process. Here, we

  9. Gamma-Ray Bursts and Relativistic Shells: The Surface Filling Factor

    International Nuclear Information System (INIS)

    Fenimore, E.E.; Cooper, C.; Ramirez-Ruiz, E.; Sumner, M.C.; Yoshida, A.; Namiki, M.

    1999-01-01

    The variability observed in many complex gamma-ray bursts (GRBs) is inconsistent with causally connected variations in a single, symmetric, relativistic shell interacting with the ambient material (open-quotes external shocksclose quotes). Rather, either the central site must produce ∼10 50 ergs s -1 for hundreds of seconds (open-quotes internal shocksclose quotes), or the local spherical symmetry of the shell must be broken on an angular scale much smaller than Γ -1 , where Γ is the bulk Lorentz factor for the shell. The observed variability in the external shock models arises from the number of causally connected regions that (randomly) become active. We define the surface filling factor to be the ratio of the area of causally connected regions that become active to the observable area of the shell. From the observed variability in 52 BATSE bursts, we estimate the surface filling factor to be typically ∼5x10 -3 , although some values are near unity. We find that the surface filling factor, f, is ∼0.1ΔT/T in both the constant Γ phase (which probably produces the GRB) and the decelerating phase (which probably produces the X-ray afterglows). Here, ΔT is a typical timescale of variability, and T is the time since the initial signal. We analyze the 2 hr flare seen by ASCA 36 hr after the GRB and conclude that the surface filling factor must be small (10 -3 ) in the X-ray afterglow phase as well. Compared with the energy required for an isotropic shell, E iso , explanations for a low surface filling factor can either require more energy (f -1 E iso ∼10 56 ergs) or less energy [(ΔT/4T) 2 E iso ∼10 49 ergs]. Thus, the low filling factor cannot be used as a strong argument that GRBs must be internal shocks. copyright copyright 1999. The American Astronomical Society

  10. Applications of factor analysis to electron and ion beam surface techniques

    International Nuclear Information System (INIS)

    Solomon, J.S.

    1987-01-01

    Factor analysis, a mathematical technique for extracting chemical information from matrices of data, is used to enhance Auger electron spectroscopy (AES), core level electron energy loss spectroscopy (EELS), ion scattering spectroscopy (ISS), and secondary ion mass spectroscopy (SIMS) in studies of interfaces, thin films, and surfaces. Several examples of factor analysis enhancement of chemical bonding variations in thin films and at interfaces studied with AES and SIMS are presented. Factor analysis is also shown to be of great benefit in quantifying electron and ion beam doses required to induce surface damage. Finally, examples are presented of the use of factor analysis to reconstruct elemental profiles when peaks of interest overlap each other during the course of depth profile analysis. (author)

  11. Surface Water Quality Assessment and Prioritize the Factors Pollute This Water Using Topsis Fuzzy Hierarchical Analysis

    Directory of Open Access Journals (Sweden)

    Mehdi Komasi

    2017-03-01

    Full Text Available Background & Objective: Nowadays, according to growth of industry and increasing population, water resources are seriousely shortened. This lack of water resources will require special management to be considered in industry and agriculture. Among the various sources of water, surface waters are more susceptible to infection. The most important of these sources of pollution are industrial pollution, detergent, pesticides, radioactive materials, heat and salt concentration.  Materials & methods: In this article, at first the importance of each pollutant will be evaluated base on the effects and its results and then quality evaluation of surface water will be studied. In order to assess the relative importance of these pollutants primarily using TOPSIS software, prioritize these factors as one of the hierarchical analysis and then is modeled with decision tree method using Weka software, the importance of each factor is evaluated and if it does not meet the minimal importance of the decision tree will be removed. Results: The results obtained from the Topsis fuzzy analysis indicate that surface water and groundwater are exposed to pollution about 74% and 26% respectively among the six pollutants examined in this study. In addition, results obtaned from the hierarchical tree in software Weka has shown that the heat factor, soluble salts and industrial pollutants give impac factor or purity about 0.1338, 0.0523 and 1.2694 respectively. Conclusion: Surface water is at greater risk of being polluted compared with groundwater. The heat factor and low concentration of dissolved salts have the low impact and industrial pollutants are considered as the most influential factors in surface water pollution.

  12. An experimental method to determine the electrostatic field enhancement factor of a practical conductor surface

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C

    1989-01-01

    A method of determining the field enhancement factor of a practical conductor is presented. The method is developed from a modified theory of discharge onset in a gaseous medium. This modification incorporates the influence of conductor surface roughness. Onset data from an experimental study...

  13. Basement to surface expressions and critical factors in the genesis of unconformity-related deposits

    International Nuclear Information System (INIS)

    Potter, Eric

    2014-01-01

    Two subprojects: 1) Basement to surface expressions of deep mineralization and refinement of critical factors leading to the genesis of unconformity-related uranium deposits; and 2) Recognition of uranium ore system alteration signatures in complex terranes: IOCG vs albite-hosted uranium vs volcanic-hosted uranium.

  14. Evaluation of stress intensity factor for craks in surface of tubes with internal pressure

    International Nuclear Information System (INIS)

    Cesari, F.; Hellen, T.K.

    1977-01-01

    In this report the authors have examined the different methods for calculation of the stress intensity factor in tubes subject at internal pressure with surface cracks. The analysis includes cracks in 2-D axialsymmetric and 3-D. Moreover the authors have clarified the difference between the ASME Sec.11 and the procedure more rigorous

  15. Analysis of stress intensity factors for surface cracks in pre/post penetration

    International Nuclear Information System (INIS)

    Miyoshi, Toshiro; Yoshida, Yuichiro

    1988-01-01

    It is important to evaluate the penetration of surface cracks in a Leak-Before-Break analysis. Because the stress intensity factors for surface cracks in pre/post penetration had not yet been analyzed, the authors carried three-dimensional boundary element analyses in order to obtain them. First, the authors developed the technique of nodal breakdown appropriate for cracks with short ligament length in a two-dimensional boundary element analysis. Next, analyses of stress intensity factor for surface cracks in pre/post penetration were carried out using the technique of nodal breakdown for cracks with short ligament length and the three-dimensional boundary element code BEM 3 D which was designed for a supercomputer. (author)

  16. Influence of physicochemical factors on microplasticity of surface layer of molybdenum single crystals

    International Nuclear Information System (INIS)

    Savenko, V.I.; Kuchumova, V.M.; Kochanova, L.A.; Shchukin, E.D.

    1984-01-01

    Microplasticity of the surface layer (not more than 10 μm) of a molybdenum monocrystal was investigated by the methods of ultramicrosclerometry and microindentation. Tests of samples with clean surface and with monolayer octadecylamine film were conducted in the air at 60% relative humidity. Microplastic deformation of samples was conducted by slipping of garnet needle on crystal surface with 10 -6 -10 -2 N force. Sclerograms represented etch pits corresponding to dislocation discharges on the surface. The linear density of dislocations in indentor routes and statistic factor (the probability of plastic deformation at assigned force) were used as microplasticity characteristics. It was revealed that plane (111) is the most prone to plastic damage and plane (100) is the least prone to it

  17. Shielding factors for gamma radiation from activity deposited on structures and ground surfaces

    International Nuclear Information System (INIS)

    Hedemann Jensen, P.

    1982-11-01

    This report describes a computer model that calculates shielding factors for indoor residence in multistorey and single-family houses for gamma radiation from activity despoited on roofs, outer walls, and ground surfaces. The dimensions of the buildings including window areas and the nearby surroundings has to be speficied in the calculations. Shielding factors can be calculated for different photon energies and for a uniform surface activity distribution as well as for separate activity on roof, outer wall, and ground surface achieved from decontamination or different deposition velocities. For a given area with a known distribution of different houses a weighted shielding factor can be calculated as well as a time-averaged one based on a given residence time distribution for work/school, home, outdoors, and transportation. Calculated shielding factors are shown for typical Danish houses. To give an impression of the sensitivity of the shielding factor on the parameters used in the model, variations were made in some of the most important parameters: wall thickness, road and ground width, percentage of outer wall covered by windows, photon energy, and decontamination percentage for outer walls, ground and roofs. The uncertainity of the calculations is discussed. (author)

  18. Modification of transition's factor in the compact surface-potential-based MOSFET model

    Directory of Open Access Journals (Sweden)

    Kevkić Tijana

    2016-01-01

    Full Text Available The modification of an important transition's factor which enables continual behavior of the surface potential in entire useful range of MOSFET operation is presented. The various modifications have been made in order to obtain an accurate and computationally efficient compact MOSFET model. The best results have been achieved by introducing the generalized logistic function (GL in fitting of considered factor. The smoothness and speed of the transition of the surface potential from the depletion to the strong inversion region can be controlled in this way. The results of the explicit model with this GL functional form for transition's factor have been verified extensively with the numerical data. A great agreement was found for a wide range of substrate doping and oxide thickness. Moreover, the proposed approach can be also applied on the case where quantum mechanical effects play important role in inversion mode.

  19. Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

    Science.gov (United States)

    Zuluaga-Ramírez, Pablo; Frövel, Malte; Belenguer, Tomás; Salazar, Félix

    2015-01-01

    This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL) and realistic variable amplitude loads (VAL), representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications. PMID:28793655

  20. Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

    Directory of Open Access Journals (Sweden)

    Pablo Zuluaga-Ramírez

    2015-11-01

    Full Text Available This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL and realistic variable amplitude loads (VAL, representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.

  1. Removal factor determination of some local smear papers for surface contamination smear test

    International Nuclear Information System (INIS)

    Suratman; Indriyotomo, D.; Aminjoyo, S.

    1996-01-01

    Removal factor determination of some local smear papers has been done, using dry smear test method. The aim of this research is to find removal values of local smear papers on some surfaces, to replace import smear papers. Smear test was done on the various surfaces i.e.: porcelain, formica, glass, stainless steel, steel and PVC, with the local smear papers I.e.: Padalarang, Diagonal, Concorde, Marga, Hard Cloth, and import smear paper. The artificial contaminant which used were I-131 and P-32. The removal factor values of Padalarang paper for surfaces: porcelain, formica, glass stainless steel, steel and PVC were: 24.5%, 20.0%, 27.0%, 6.8%, 4.9%, and 13.6% respectively. The removal factor values of Diagonal paper were:18.4%, 15.9%, 5.7%, 3.5%, and 9.1% respectively. The removal factor values of concord paper were: 18.5%, 20.3%, 23.1%, 6.6%, 3.8%, and 9.0% respectively. The removal factor values of Marga paper were: 16.7%, 13.5%, 21.1%, 4.2%, 4.1% and 8.1% respectively. The removal factor values of Hard Cloth were: 18.6%, 12.6%, 20.5%, 8.2%, and 10.1% respectively. The removal factor values of import smear paper were: 17.8%, 15.0%, 18.8%, 9.1%, 4.8%, and 14.4% respectively . Substitution alternative of import smear paper is Padalarang. (author)

  2. Determination of conversion factors and efficiency for GM detectors used in measurements of surface pollution

    International Nuclear Information System (INIS)

    Ayala G, J.; Alvarez R, J.T.

    1999-01-01

    One of the objectives of the Radiation protection, is to observe with the National and as International standardization referring to the ICRP dose limitation system (ICRP 26, ICRP 60). In this work it was treated the problem corresponding about how to determine the conversion factor of cpm/mR/h and the absolute efficiency ε, for a Geiger-Muller equipment with thin window. This equipment is used for the beta particle detection. Thus the correct use of calibration factors and the procedures to convert cpm in Bq is expedited and also to apply the ISO procedure for to evaluate contaminated surfaces. (Author)

  3. A sensitive electrochemiluminescence cytosensor for quantitative evaluation of epidermal growth factor receptor expressed on cell surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yanjuan; Zhang, Shaolian; Wen, Qingqing; Huang, Hongxing; Yang, Peihui, E-mail: typh@jnu.edu.cn

    2015-06-30

    Highlights: • EGF-cytosensor was used for evaluating EGFR expression level on cell surfaces. • CdSQDs and EGF were coated on magnetic beads (MBs) for ECL-probe. • Good sensitivity was achieved due to the signal amplification of ECL-probe. - Abstract: A sensitive electrochemiluminescence (ECL) strategy for evaluating the epidermal growth factor receptor (EGFR) expression level on cell surfaces was designed by integrating the specific recognition of EGFR expressed on MCF-7 cell surfaces with an epidermal growth factor (EGF)-funtionalized CdS quantum dots (CdSQDs)-capped magnetic bead (MB) probe. The high sensitivity of ECL probe of EGF-funtionalized CdSQD-capped-MB was used for competitive recognition with EGFR expressed on cell surfaces with recombinant EGFR protein. The changes of ECL intensity depended on both the cell number and the expression level of EGFR receptor on cell surfaces. A wide linear response to cells ranging from 80 to 4 × 10{sup 6} cells mL{sup −1} with a detection limit of 40 cells mL{sup −1} was obtained. The EGF-cytosensor was used to evaluate EGFR expression levels on MCF-7 cells, and the average number of EGFR receptor on single MCF-7 cells was 1.35 × 10{sup 5} with the relative standard deviation of 4.3%. This strategy was further used for in-situ and real-time evaluating EGFR receptor expressed on cell surfaces in response to drugs stimulation at different concentration and incubation time. The proposed method provided potential applications in the detection of receptors on cancer cells and anticancer drugs screening.

  4. Tailoring Surface Impurity Content to Maximize Q-factors of Superconducting Resonators

    Energy Technology Data Exchange (ETDEWEB)

    Martinello, Martina [Illinois Inst. of Technology, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Grassellino, Anna [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Melnychuk, Oleksandr [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Posen, Sam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Romanenko, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sergatskov, Dmitri [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zasadzinski, John [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-06-01

    Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of flux trapped, depends on the mean free path. A variety of 1.3 GHz cavities with different surface treatments (EP, 120 C bake and different N-doping) were studied in order to cover the largest range of mean free path nowadays achievable, from few to thousands of nanometers. A bell shaped trend appears for the range of mean free path studied. Over doped cavities falls at the maximum of this curve defining the largest values of sensitivity. In addition, we have also studied the trend of the BCS surface resistance contribution as a function of mean free path, revealing that N-doped cavities follow close to the theoretical minimum of the BCS surface resistance as a function of the mean free path. Adding these results together we unveil that optimal N-doping treatment allows to maximize Q-factor at 2 K and 16 MV/m until the magnetic field fully trapped during the cavity cooldown stays below 10 mG.

  5. Analysis of the Pathogenic Factors and Management of Dry Eye in Ocular Surface Disorders.

    Science.gov (United States)

    Nebbioso, Marcella; Del Regno, Paola; Gharbiya, Magda; Sacchetti, Marta; Plateroti, Rocco; Lambiase, Alessandro

    2017-08-13

    The tear film represents the interface between the eye and the environment. The alteration of the delicate balance that regulates the secretion and distribution of the tear film determines the dry eye (DE) syndrome. Despite having a multifactorial origin, the main risk factors are female gender and advanced age. Likewise, morphological changes in several glands and in the chemical composition of their secretions, such as proteins, mucins, lipidics, aqueous tears, and salinity, are highly relevant factors that maintain a steady ocular surface. Another key factor of recurrence and onset of the disease is the presence of local and/or systemic inflammation that involves the ocular surface. DE syndrome is one of the most commonly encountered diseases in clinical practice, and many other causes related to daily life and the increase in average life expectancy will contribute to its onset. This review will consider the disorders of the ocular surface that give rise to such a widespread pathology. At the end, the most recent therapeutic options for the management of DE will be briefly discussed according to the specific underlying pathology.

  6. Effect of extracytoplasmic function sigma factors on autoaggregation, hemagglutination, and cell surface properties of Porphyromonas gingivalis

    Science.gov (United States)

    Kokubu, Eitoyo; Okamoto-Shibayama, Kazuko; Ishihara, Kazuyuki

    2017-01-01

    Porphyromonas gingivalis is a bacterium frequently isolated from chronic periodontal lesions and is involved in the development of chronic periodontitis. To colonize the gingival crevice, P. gingivalis has to adapt to environmental stresses. Microbial gene expression is regulated by transcription factors such as those in two-component systems and extracytoplasmic function (ECF) sigma factors. ECF sigma factors are involved in the regulation of environmental stress response genes; however, the roles of individual ECF sigma factors are largely unknown. The purpose of this study was to investigate the functions, including autoaggregation, hemagglutination, gingipain activity, susceptibility to antimicrobial agents, and surface structure formation, of P. gingivalis ECF sigma factors encoded by SigP (PGN_0274), SigCH (PGN_0319), PGN_0450, PGN_0970, and SigH (PGN_1740). Various physiological aspects of the sigP mutant were affected; autoaggregation was significantly decreased at 60 min (p < 0.001), hemagglutination activity was markedly reduced, and enzymatic activities of Kgp and Rgps were significantly decreased (p < 0.001). The other mutants also showed approximately 50% reduction in Rgps activity. Kgp activity was significantly reduced in the sigH mutant (p < 0.001). No significant differences in susceptibilities to tetracycline and ofloxacin were observed in the mutants compared to those of the wild-type strain. However, the sigP mutant displayed an increased susceptibility to ampicillin, whereas the PGN_0450 and sigH mutants showed reduced susceptibility. Transmission electron microscopy images revealed increased levels of outer membrane vesicles formed at the cell surfaces of the sigP mutant. These results indicate that SigP is important for bacterial surface-associated activities, including gingipain activity, autoaggregation, hemagglutination, vesicle formation, and antimicrobial susceptibility. PMID:28931045

  7. Probing electronic phase transitions with phonons via inelastic neutron scattering: superconductivity in borocarbides, charge and magnetic order in manganites

    Energy Technology Data Exchange (ETDEWEB)

    Weber, F.

    2007-11-02

    the intrinsic phonon linewidth near the order wave vector of the short-range charge and orbital order present above T{sub C}. In an neutron powder diffraction measurement at the Hahn-Meitner Institut in Berlin, we investigated the temperature dependence of the anisotropic Debye-Waller factors of the oxygen atoms in La{sub 0.7}Sr{sub 0.3}MnO{sub 3}. According to the present point of view, the sudden increase of the Debye-Waller factors at T{sub C} should be proportional to the strength of the colossal magnetoresistance effect. However, we found experimental values for La{sub 0.7}Sr{sub 0.3}MnO{sub 3}, which are in close vicinity or even bigger than values of compounds with a much stronger magnetoresistance effect. (orig.)

  8. Probing electronic phase transitions with phonons via inelastic neutron scattering: superconductivity in borocarbides, charge and magnetic order in manganites

    International Nuclear Information System (INIS)

    Weber, F.

    2007-01-01

    wave vector of the short-range charge and orbital order present above T C . In an neutron powder diffraction measurement at the Hahn-Meitner Institut in Berlin, we investigated the temperature dependence of the anisotropic Debye-Waller factors of the oxygen atoms in La 0.7 Sr 0.3 MnO 3 . According to the present point of view, the sudden increase of the Debye-Waller factors at T C should be proportional to the strength of the colossal magnetoresistance effect. However, we found experimental values for La 0.7 Sr 0.3 MnO 3 , which are in close vicinity or even bigger than values of compounds with a much stronger magnetoresistance effect. (orig.)

  9. Porphyromonas gingivalis Uses Specific Domain Rearrangements and Allelic Exchange to Generate Diversity in Surface Virulence Factors.

    Science.gov (United States)

    Dashper, Stuart G; Mitchell, Helen L; Seers, Christine A; Gladman, Simon L; Seemann, Torsten; Bulach, Dieter M; Chandry, P Scott; Cross, Keith J; Cleal, Steven M; Reynolds, Eric C

    2017-01-01

    Porphyromonas gingivalis is a keystone pathogen of chronic periodontitis. The virulence of P. gingivalis is reported to be strain related and there are currently a number of strain typing schemes based on variation in capsular polysaccharide, the major and minor fimbriae and adhesin domains of Lys-gingipain (Kgp), amongst other surface proteins. P. gingivalis can exchange chromosomal DNA between strains by natural competence and conjugation. The aim of this study was to determine the genetic variability of P. gingivalis strains sourced from international locations over a 25-year period and to determine if variability in surface virulence factors has a phylogenetic basis. Whole genome sequencing was performed on 13 strains and comparison made to 10 previously sequenced strains. A single nucleotide polymorphism-based phylogenetic analysis demonstrated a shallow tri-lobed phylogeny. There was a high level of reticulation in the phylogenetic network, demonstrating extensive horizontal gene transfer between the strains. Two highly conserved variants of the catalytic domain of the major virulence factor the Kgp proteinase (Kgp cat I and Kgp cat II) were found. There were three variants of the fourth Kgp C-terminal cleaved adhesin domain. Specific variants of the cell surface proteins FimA, FimCDE, MfaI, RagAB, Tpr, and PrtT were also identified. The occurrence of all these variants in the P. gingivalis strains formed a mosaic that was not related to the SNP-based phylogeny. In conclusion P. gingivalis uses domain rearrangements and genetic exchange to generate diversity in specific surface virulence factors.

  10. Controls of evapotranspiration and CO2 fluxes from scots pine by surface conductance and abiotic factors.

    Directory of Open Access Journals (Sweden)

    Tianshan Zha

    Full Text Available Evapotranspiration (E and CO2 flux (Fc in the growing season of an unusual dry year were measured continuously over a Scots pine forest in eastern Finland, by eddy covariance techniques. The aims were to gain an understanding of their biological and environmental control processes. As a result, there were obvious diurnal and seasonal changes in E, Fc , surface conductance (gc , and decoupling coefficient (Ω, showing similar trends to those in radiation (PAR and vapour pressure deficit (δ. The maximum mean daily values (24-h average for E, Fc , gc , and Ω were 1.78 mmol m(-2 s(-1, -11.18 µmol m(-2 s(-1, 6.27 mm s(-1, and 0.31, respectively, with seasonal averages of 0.71 mmol m(-2 s(-1, -4.61 µmol m(-2 s(-1, 3.3 mm s(-1, and 0.16. E and Fc were controlled by combined biological and environmental variables. There was curvilinear dependence of E on gc and Fc on gc . Among the environmental variables, PAR was the most important factor having a positive linear relationship to E and curvilinear relationship to Fc , while vapour pressure deficit was the most important environmental factor affecting gc . Water use efficiency was slightly higher in the dry season, with mean monthly values ranging from 6.67 to 7.48 μmol CO2 (mmol H2O(-1 and a seasonal average of 7.06 μmol CO2 (μmol H2O(-1. Low Ω and its close positive relationship with gc indicate that evapotranspiration was sensitive to surface conductance. Mid summer drought reduced surface conductance and decoupling coefficient, suggesting a more biotic control of evapotranspiration and a physiological acclimation to dry air. Surface conductance remained low and constant under dry condition, supporting that a constant value of surface constant can be used for modelling transpiration under drought condition.

  11. Fate factors and emission flux estimates for emerging contaminants in surface waters

    Directory of Open Access Journals (Sweden)

    Hoa T. Trinh

    2016-01-01

    Full Text Available Pharmaceuticals, personal care products, hormones, and wastewater products are emerging environmental concerns for manifold reasons, including the potential of some compounds found in these products for endocrine disruption at a very low chronic exposure level. The environmental occurrences and sources of these contaminants in the water, soil, sediment and biota in European nations and the United States are well documented. This work reports a screening-level emission and fate assessment of thirty compounds, listed in the National Reconnaissance of the United States Geological Survey (USGS, 1999–2000 as the most frequently detected organic wastewater contaminants in U.S. streams and rivers. Estimations of the surface water fate factors were based on Level II and Level III multimedia fugacity models for a 1000 km2 model environment, the size of a typical county in the eastern United States. The compounds are categorized into three groups based upon the sensitivity of their predicted surface water fate factors to uncertainties in their physicochemical property values and the landscape parameters. The environmental fate factors, mass distributions, and loss pathways of all of the compounds are strongly affected by their assumed modes of entry into the environment. It is observed that for thirteen of the thirty organic wastewater contaminants most commonly detected in surface waters, conventional treatment strategies may be ineffective for their removal from wastewater effluents. The surface water fate factors predicted by the fugacity models were used in conjunction with the surface water concentrations measured in the USGS reconnaissance to obtain emission flux estimates for the compounds into U.S. streams and rivers. These include estimated fluxes of 6.8 × 10−5 to 0.30 kg/h km2 for the biomarker coprostanol; 1.7 × 10−5 to 6.5 × 10−5 kg/h km2 for the insect repellent N,N-diethyltoluamide; and 4.3 × 10−6 to 3.1 × 10−5 kg/h km2 for

  12. Shoe and field surface risk factors for acute lower extremity injuries among female youth soccer players

    Science.gov (United States)

    O'Kane, John W.; Gray, Kristen E.; Levy, Marni R.; Neradilek, Moni; Tencer, Allan F.; Polissar, Nayak L.; Schiff, Melissa A.

    2015-01-01

    Objective Describe acute lower extremity injuries and evaluate extrinsic risk factors in female youth soccer Design Nested case-control study Setting Youth soccer clubs in Washington State, USA. Participants Female soccer players (N= 351) ages 11 to 15 years randomly selected from 4 soccer clubs from which 83% of their players were enrolled with complete follow-up for 92% of players. Interventions Injured players were interviewed regarding injury, field surface, shoe type, and position. Uninjured controls, matched on game or practice session, were also interviewed. Main Outcome Measures The association between risk factors and acute lower extremity injury using logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI). Results One hundred seventy-three acute lower extremity injuries occurred involving primarily the ankle (39.3%), knee (24.9%), and thigh (11.0%). Over half (52.9%) recovered within 1 week, while 30.2% lasted beyond 2 weeks. During practices, those injured were approximately 3-fold ( OR 2.83, 95% CI 1.49-5.31) more likely to play on grass than artificial turf and 2.4-fold (95% CI 1.03-5.96) more likely to wear cleats on grass than other shoe and surface combinations. During games injured players were 89% (95% CI 1.03-4.17) more likely to play defender compared to forward. Conclusions Half of the acute lower extremity injuries affected the ankle or knee. Grass surface and wearing cleats on grass increased training injuries. PMID:26327288

  13. Limonene inhibits streptococcal biofilm formation by targeting surface-associated virulence factors.

    Science.gov (United States)

    Subramenium, Ganapathy Ashwinkumar; Vijayakumar, Karuppiah; Pandian, Shunmugiah Karutha

    2015-08-01

    The present study explores the efficacy of limonene, a cyclic terpene found in the rind of citrus fruits, for antibiofilm potential against species of the genus Streptococcus, which have been deeply studied worldwide owing to their multiple pathogenic efficacy. Limonene showed a concentration-dependent reduction in the biofilm formation of Streptococcus pyogenes (SF370), with minimal biofilm inhibitory concentration (MBIC) of 400 μg ml - 1. Limonene was found to possess about 75-95 % antibiofilm activity against all the pathogens tested, viz. Streptococcus pyogenes (SF370 and 5 clinical isolates), Streptococcus mutans (UA159) and Streptococcus mitis (ATCC 6249) at 400 μg ml - 1 concentration. Microscopic analysis of biofilm architecture revealed a quantitative breach in biofilm formation. Results of a surface-coating assay suggested that the possible mode of action of limonene could be by inhibiting bacterial adhesion to surfaces, thereby preventing the biofilm formation cascade. Susceptibility of limonene-treated Streptococcus pyogenes to healthy human blood goes in unison with gene expression studies in which the mga gene was found to be downregulated. Anti-cariogenic efficacy of limonene against Streptococcus mutans was confirmed, with inhibition of acid production and downregulation of the vicR gene. Downregulation of the covR, mga and vicR genes, which play a critical role in regulating surface-associated proteins in Streptococcus pyogenes and Streptococcus mutans, respectively, is yet further evidence to show that limonene targets surface-associated proteins. The results of physiological assays and gene expression studies clearly show that the surface-associated antagonistic mechanism of limonene also reduces surface-mediated virulence factors.

  14. [Factors related to the influence on congenital malformation of body surface in Shaanxi province].

    Science.gov (United States)

    Ying, J; Lei, Q; Qin, B W; Qu, P F; Lei, F L; Dang, S N; Zeng, L X; Yan, H

    2016-12-10

    Objective: To investigate the influencing factors on congenital malformation of body surface. Methods: Multi-stage stratified random sampling method was adopted. A questionnaire survey was conducted among the childbearing aged women who experienced more than 28 weeks pregnancy or having definite pregnancy outcomes in Shaanxi, during 2010-2013. Results: Results from the logistic regression model showed that factors as: intrahepatic cholestasis of pregnancy ( OR =21.76, 95 %CI : 4.46-106.25), histories with abnormal pregnancy or reproduction ( OR =11.88, 95 %CI : 9.14-15.45), having birth defects in the family ( OR =6.15, 95 %CI : 2.66-14.23), being twins ( OR =5.74, 95 % CI : 3.34-9.86), being worker (compared with others, OR =2.47, 95 % CI : 1.30-4.68) or farmer (compared with others, OR =1.91, 95 %CI : 1.14-3.20), less than 4 times of antenatal care (compared with >7, OR =1.84, 95 % CI : 1.28-2.64), occupational exposure to related risks during pregnancy ( OR =1.74, 95 % CI : 1.26-2.42), mother's hometown was from mid-part of Shaanxi (compared with northern Shaanxi, OR =1.65, 95 %CI : 1.20-2.28), mother's native residence was from the rural areas ( OR =1.75, 95 % CI : 1.13-2.71), drug use ( OR =1.64, 95 % CI : 1.26-2.13) etc . were risk factors for congenital malformation of body surface. Iron supplement during pregnancy ( OR =0.46, 95 %CI : 0.21-0.99) appeared as protective factor for congenital malformation of body surface. Conclusion: The following factors seemed to be of risk for congenital malformation of body surface, including: mother's native area was from the middle part of Shaanxi and living in rural area, being worker or farmer, histories of abnormal pregnancy and reproduction, history of birth defects in the family, being twins, with antenatal care less than 4 times, occupational exposure to dangerous materials, drug use, intrahepatic cholestasis during pregnancy etc .

  15. Mechanical Q-factor measurements on a test mass with a structured surface

    Energy Technology Data Exchange (ETDEWEB)

    Nawrodt, R [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Zimmer, A [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Koettig, T [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Clausnitzer, T [Institut fuer Angewandte Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Bunkowski, A [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany); Kley, E B [Institut fuer Angewandte Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Schnabel, R [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany); Danzmann, K [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut) and Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, Callinstr. 38, D-30167 Hannover (Germany); Nietzsche, S [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Vodel, W [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany); Tuennermann, A [Institut fuer Angewandte Physik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Seidel, P [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Helmholtzweg 5, D-07743 Jena (Germany)

    2007-07-15

    We present mechanical Q-factors (quality factors) of a crystalline quartz test mass with a nano-structured surface, measured in the temperature regime from 5 to 300 K. The nano-structure was a grating with a period of 2 {mu}m and a depth of about 0.1 {mu}m. Comparative measurements were performed on the plain substrate and on the structured test mass with different numbers of SiO{sub 2}/Ta{sub 2}O{sub 5} coating layers. The measurements at different stages of the test mass fabrication process show that the surface distortion induced by the nanostructure does not severely lower the mechanical Q-factor of the substrate. Damping due to a multi-layer coating stack was found to be orders of magnitude higher. The results provide vital information concerning the potential usage of low-thermal noise nano-structured test masses in future generations of high-precision laser interferometers and in current attempts to measure quantum effects of macroscopic mirror oscillators.

  16. Shielding Factors for Gamma Radiation from Activity Deposited on Structures and Ground Surfaces

    DEFF Research Database (Denmark)

    Jensen, Per Hedemann

    1985-01-01

    A computer model DEPSHIELD for the calculation of shielding factors for gamma radiation at indoor residences in multistorey and single-family houses has been developed. The model is based on the exponential point kernel that links the radiation flux density at a given detector point to a point...... it possible to determine the dose reduction effect from a decontamination of the different surfaces. The model has been used in a study of the consequences of land contamination of Danish territory after hypothetical core-melt accidents at the Barseback nuclear power plant in Sweden. The model has also been...

  17. Root caries, root surface restorations and lifestyle factors in adult Danes

    DEFF Research Database (Denmark)

    Christensen, Lisa Bøge; Bardow, Allan; Ekstrand, Kim

    2015-01-01

    , tobacco use and oral hygiene routines were collected from 4369 adults aged 21-89 who took part in a survey covering 13 municipalities across Denmark. Uni- and multivariate logistic regression analyses were applied to analyse the relationship between the independent lifestyle variables and active caries...... consumption, as well as wearing dentures, were significantly associated with the occurrence of untreated caries and restored root surface lesions, especially in persons over 45. Thus, such lifestyle factors should be taken into consideration, identifying persons with a need of preventive dental services...

  18. Surface water acidification and critical loads: exploring the F-factor

    Directory of Open Access Journals (Sweden)

    K. Bishop

    2009-11-01

    Full Text Available As acid deposition decreases, uncertainties in methods for calculating critical loads become more important when judgements have to be made about whether or not further emission reductions are needed. An important aspect of one type of model that has been used to calculate surface water critical loads is the empirical F-factor which estimates the degree to which acid deposition is neutralised before it reaches a lake at any particular point in time relative to the pre-industrial, steady-state water chemistry conditions.

    In this paper we will examine how well the empirical F-functions are able to estimate pre-industrial lake chemistry as lake chemistry changes during different phases of acidification and recovery. To accomplish this, we use the dynamic, process-oriented biogeochemical model SAFE to generate a plausible time series of annual runoff chemistry for ca. 140 Swedish catchments between 1800 and 2100. These annual hydrochemistry data are then used to generate empirical F-factors that are compared to the "actual" F-factor seen in the SAFE data for each lake and year in the time series. The dynamics of the F-factor as catchments acidify, and then recover are not widely recognised.

    Our results suggest that the F-factor approach worked best during the acidification phase when soil processes buffer incoming acidity. However, the empirical functions for estimating F from contemporary lake chemistry are not well suited to the recovery phase when the F-factor turns negative due to recovery processes in the soil. This happens when acid deposition has depleted the soil store of BC, and then acid deposition declines, reducing the leaching of base cations to levels below those in the pre-industrial era. An estimate of critical load from water chemistry during recovery and empirical F functions would therefore result in critical loads that are too low. Therefore, the empirical estimates of the F-factor are a significant source of

  19. Development of new Z-factors for the evaluation of the circumferential surface crack in nuclear pipes

    International Nuclear Information System (INIS)

    Choi, Y.H.; Chung, Y.K.; Park, Y.W.; Lee, J.B.

    1997-01-01

    The purpose of this study is to develop new Z-factors to evaluate the behavior of a circumferential surface crack in nuclear pipe. Z-factor is a load multiplier used in the Z-factor method, which is one of the ASME Code Sec. XI's recommendations for the estimation of a surface crack in nuclear pipe. It has been reported that the load carrying capacities predicted from the current ASME Code Z-factors, are not well in agreement with the experimental results for nuclear pipes with a surface crack. In this study, new Z-factors for ferritic base metal, ferritic submerged arc welding (SAW) weld metal, austenitic base metal, and austenitic SAW weld metal are obtained by use of the surface crack for thin pipe (SC.TNP) method based on GE/EPRI method. The desirability of both the SC.TNP method and the new Z-factors is examined using the results from 48 pipe fracture experiments for nuclear pipes with a circumferential surface crack. The results show that the SC.TNP method is good for describing the circumferential surface crack behavior and the new Z-factors are well in agreement with the measured Z-factors for both ferritic and austenitic pipes. (orig.)

  20. Plasma Rich in Growth Factors for the Treatment of Ocular Surface Diseases.

    Science.gov (United States)

    Anitua, Eduardo; Muruzabal, Francisco; de la Fuente, María; Merayo, Jesús; Durán, Juan; Orive, Gorka

    2016-07-01

    The purpose of this work is to describe and review the technology of plasma rich in growth factors (PRGF), a novel blood derivative product, in the treatment of ocular surface disorders. To demonstrate the importance of this technology in the treatment of ocular pathologies, a thorough review of the preclinical and clinical literature results obtained following use of the different therapeutic formulations of PRGF was carried out. A literature search for applications of PGRF plasma in the ophthalmology field was carried out using the PubMed database. PRGF involves the use of patient's own biologically active proteins, growth factors, and biomaterial scaffolds for therapeutic purposes. This procedural technology is gaining interest in regenerative medicine due to its potential to stimulate and accelerate the tissue healing processes. The versatility and biocompatibility of this technology opens the door to a personalized medicine on ocular tissue regeneration. This review discusses the state of the art of the new treatments and technologies developed to promote ocular surface tissue regeneration. The standardized protocol that has been developed to source eye drops from PRGF technology is also described. The preclinical research, together with the most relevant clinical applications are summarized and discussed. The preliminary results suggest that the use of PRGF to enhance ocular tissue regeneration is safe and efficient.

  1. Factors Influencing NO2 Adsorption/Reduction on Microporous Activated Carbon: Porosity vs. Surface Chemistry

    Directory of Open Access Journals (Sweden)

    Imen Ghouma

    2018-04-01

    Full Text Available The textural properties and surface chemistry of different activated carbons, prepared by the chemical activation of olive stones, have been investigated in order to gain insight on the NO2 adsorption mechanism. The parent chemical activated carbon was prepared by the impregnation of olive stones in phosphoric acid followed by thermal carbonization. Then, the textural properties and surface chemistry were modified by chemical treatments including nitric acid, sodium hydroxide and/or a thermal treatment at 900 °C. The main properties of the parent and modified activated carbons were analyzed by N2-adsorption, scanning electron microscopy (SEM, and Fourier transform infrared spectroscopy (FTIR techniques, in order to enlighten the modifications issued from the chemical and thermal treatments. The NO2 adsorption capacities of the different activated carbons were measured in fixed bed experiments under 500 ppmv NO2 concentrations at room temperature. Temperature programmed desorption (TPD was applied after adsorption tests in order to quantify the amount of the physisorbed and chemisorbed NO2. The obtained results showed that the development of microporosity, the presence of oxygen-free sites, and the presence of basic surface groups are key factors for the efficient adsorption of NO2.

  2. Factors affecting the wettability of different surface materials with vegetable oil at high temperatures and its relation to cleanability

    DEFF Research Database (Denmark)

    Ashokkumar, Saranya; Adler-Nissen, Jens; Møller, Per

    2012-01-01

    The main aim of the work was to investigate the wettability of different surface materials with vegetable oil (olive oil) over the temperature range of 25–200°C to understand the differences in cleanability of different surfaces exposed to high temperatures in food processes. The different surface...... different levels of roughness. The cosine of the contact angle of olive oil on different surface materials rises linearly with increasing temperature. Among the materials analyzed, polymers (PTFE, silicone) gave the lowest cosθ values. Studies of the effect of roughness and surface flaws on wettability...... contact angle and cleanability. In addition to surface wettability with oil many other factors such as roughness and surface defects play an essential role in determining their cleanability....

  3. Solar wind: A possible factor driving the interannual sea surface temperature tripolar mode over North Atlantic

    Science.gov (United States)

    Xiao, Ziniu; Li, Delin

    2016-06-01

    The effect of solar wind (SW) on the North Atlantic sea surface temperature (SST) in boreal winter is examined through an analysis of observational data during 1964-2013. The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed (SWS) variations. This pattern is broadly similar to the leading empirical orthogonal function (EOF) mode of interannual variations in the wintertime SSTs over North Atlantic. The time series of this leading EOF mode of SST shows a significant interannual period, which is the same as that of wintertime SWS. This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind, which simultaneously resembles the North Atlantic Oscillation (NAO) in the overlying atmosphere. As compared with the typical low SWS winters, during the typical high SWS winters, the stratospheric polar night jet (PNJ) is evidently enhanced and extends from the stratosphere to the troposphere, even down to the North Atlantic Ocean surface. Notably, the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere. Thus, it seems that the SW is a possible factor for this North Atlantic SST tripolar mode. The dynamical process of stratosphere-troposphere coupling, together with the global atmospheric electric circuit-cloud microphysical process, probably accounts for the particular downward propagation of the SW signal.

  4. Characterization of cell-surface receptors for monoclonal-nonspecific suppressor factor (MNSF)

    International Nuclear Information System (INIS)

    Nakamura, M.; Ogawa, H.; Tsunematsu, T.

    1990-01-01

    Monoclonal-nonspecific suppressor factor (MNSF) is a lymphokine derived from murine T cell hybridoma. The target tissues are both LPS-stimulated B cells and Con A-stimulated T cells. Since the action of MNSF may be mediated by its binding to specific cell surface receptors, we characterized the mode of this binding. The purified MNSF was labeled with 125 I, using the Bolton-Hunter reagent. The labeled MNSF bound specifically to a single class of receptor (300 receptors per cell) on mitogen-stimulated murine B cells or T cells with an affinity of 16 pM at 24 degrees C, in the presence of sodium azide. Competitive experiments showed that MNSF bound to the specific receptor and that the binding was not shared with IL2, IFN-gamma, and TNF. Various cell types were surveyed for the capacity to specifically bind 125 I-MNSF. 125 I-MNSF bound to MOPC-31C (a murine plasmacytoma line) and to EL4 (a murine T lymphoma line). The presence of specific binding correlates with the capacity of the cells to respond to MNSF. These data support the view that like other polypeptide hormones, the action of MNSF is mediated by specific cell surface membrane receptor protein. Identification of these receptors will provide insight into the apparently diverse activities of MNSF

  5. A Predictive Model of Surface Warfare Officer Retention: Factors Affecting Turnover

    National Research Council Canada - National Science Library

    Gjurich, Gregory

    1999-01-01

    Junior Surface Warfare Officer retention is in a crisis. The Surface Warfare Officer community anticipates an inability to fill Department Head billets due to the number of junior Surface Warfare Officers leaving military service...

  6. Electron-beam induced amorphization of stishovite: Silicon-coordination change observed using Si K-edge extended electron energy-loss fine structure

    Science.gov (United States)

    van Aken, P. A.; Sharp, T. G.; Seifert, F.

    The analysis of the extended energy-loss fine structure (EXELFS) of the Si K-edge for sixfold-coordinated Si in synthetic stishovite and fourfold-coordinated Si in natural α-quartz is reported by using electron energy-loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM). The stishovite Si K-edge EXELFS spectra were measured as a time-dependent series to document irradiation-induced amorphization. The amorphization was also investigated through the change in Si K- and O K-edge energy-loss near edge structure (ELNES). For α-quartz, in contrast to stishovite, electron irradiation-induced vitrification, verified by selected area electron diffraction (SAED), produced no detectable changes of the EXELFS. The Si K-edge EXELFS were analysed with the classical extended X-ray absorption fine structure (EXAFS) treatment and compared to ab initio curve-waved multiple-scattering (MS) calculations of EXAFS spectra for stishovite and α-quartz. Highly accurate information on the local atomic environment of the silicon atoms during the irradiation-induced amorphization of stishovite is obtained from the EXELFS structure parameters (Si-O bond distances, coordination numbers and Debye-Waller factors). The mean Si-O bond distance R and mean Si coordination number N changes from R=0.1775 nm and N=6 for stishovite through a disordered intermediate state (R 0.172 nm and N 5) to R 0.167 nm and N 4.5 for a nearly amorphous state similar to α-quartz (R=0.1609 nm and N=4). During the amorphization process, the Debye-Waller factor (DWF) passes through a maximum value of as it changes from for sixfold to for fourfold coordination of Si. This increase in Debye-Waller factor indicates an increase in mean-square relative displacement (MSRD) between the central silicon atom and its oxygen neighbours that is consistent with the presence of an intermediate structural state with fivefold coordination of Si. The distribution of coordination states can be estimated by

  7. Factors affecting the shear bond strength of metal and ceramic brackets bonded to different ceramic surfaces.

    Science.gov (United States)

    Abu Alhaija, Elham S J; Abu AlReesh, Issam A; AlWahadni, Ahed M S

    2010-06-01

    The aims of this study were to evaluate the shear bond strength (SBS) of metal and ceramic brackets bonded to two different all-ceramic crowns, IPS Empress 2 and In-Ceram Alumina, to compare the SBS between hydrofluoric acid (HFA), phosphoric acid etched, and sandblasted, non-etched all-ceramic surfaces. Ninety-six all-ceramic crowns were fabricated resembling a maxillary left first premolar. The crowns were divided into eight groups: (1) metal brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (2) metal brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (3) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (4) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (5) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched IPS Empress 2 crowns; (6) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched In-Ceram crowns; (7) metal brackets bonded to sandblasted, non-etched IPS Empress 2 crowns; and (8) metal brackets bonded to sandblasted, non-etched In-Ceram crowns. Metal and ceramic orthodontic brackets were bonded using a conventional light polymerizing adhesive resin. An Instron universal testing machine was used to determine the SBS at a crosshead speed of 0.1 mm/minute. Comparison between groups was performed using a univariate general linear model and chi-squared tests. The highest mean SBS was found in group 3 (120.15 +/- 45.05 N) and the lowest in group 8 (57.86 +/- 26.20 N). Of all the variables studied, surface treatment was the only factor that significantly affected SBS (P Empress 2 and In-Ceram groups.

  8. Factors affecting the wettability of different surface materials with vegetable oil at high temperatures and its relation to cleanability

    Energy Technology Data Exchange (ETDEWEB)

    Ashokkumar, Saranya, E-mail: saras@food.dtu.dk [Accoat A/S, Munkegardsvej 16, 3490 Kvistgard (Denmark); Food Production Engineering, DTU FOOD, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark); Adler-Nissen, Jens [Food Production Engineering, DTU FOOD, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark); Moller, Per [Department of Materials Science and Engineering, DTU Mechanical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark)

    2012-12-15

    contact angle and cleanability. In addition to surface wettability with oil many other factors such as roughness and surface defects play an essential role in determining their cleanability.

  9. Electron dose-rate conversion factors for external exposure of the skin from uniformly deposited activity on the body surface

    International Nuclear Information System (INIS)

    Kocher, D.C.; Eckerman, K.F.

    1987-01-01

    Dose-rate conversion factors have been calculated for external exposure of the skin from electrons emitted by sources that are deposited uniformly on the body surface. The dose-rate factors are obtained from electron scaled point kernels developed by Berger. The dose-rate factors are calculated at depths of 4, 8, and 40 mg cm-2 below the body surface as recommended by Whitton, and at a depth of 7 mg cm-2 as recommended in ICRP Publication 26 (ICRP77). The dependence of the dose-rate factors at selected depths on the energy of the emitted electrons is displayed. The dose-rate factors for selected radionuclides of potential importance in radiological assessments are tabulated

  10. Non-equilibrium lattice dynamics of one-dimensional In chains on Si(111 upon ultrafast optical excitation

    Directory of Open Access Journals (Sweden)

    T. Frigge

    2018-03-01

    Full Text Available The photoinduced structural dynamics of the atomic wire system on the Si(111-In surface has been studied by ultrafast electron diffraction in reflection geometry. Upon intense fs-laser excitation, this system can be driven in around 1 ps from the insulating (8×2 reconstructed low temperature phase to a metastable metallic (4×1 reconstructed high temperature phase. Subsequent to the structural transition, the surface heats up on a 6 times slower timescale as determined from a transient Debye-Waller analysis of the diffraction spots. From a comparison with the structural response of the high temperature (4×1 phase, we conclude that electron-phonon coupling is responsible for the slow energy transfer from the excited electron system to the lattice. The significant difference in timescales is evidence that the photoinduced structural transition is non-thermally driven.

  11. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Jie [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Zhao, Changpo [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Luo, Yupeng [Department of Mathematics and Statistics, Auburn University, Auburn, AL 36849 (United States); Liu, Chunsheng, E-mail: liuchunshengidid@126.com [College of Fisheries, Huazhong Agricultural University, Wuhan 430070 (China); Kyzas, George Z. [Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Luo, Yin [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Zhao, Dongye [Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); An, Shuqing [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Zhu, Hailiang, E-mail: zhuhl@nju.edu.cn [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China)

    2014-04-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD{sub Mn} in water drove heavy metals to deposit in sediments. • B-IBI was sensitive to the adverse effect of heavy metals in sediments. - Abstract: This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community.

  12. Pathogenic Leptospira species acquire factor H and vitronectin via the surface protein LcpA.

    Science.gov (United States)

    da Silva, Ludmila Bezerra; Miragaia, Lidia Dos Santos; Breda, Leandro Carvalho Dantas; Abe, Cecilia Mari; Schmidt, Mariana Costa Braga; Moro, Ana Maria; Monaris, Denize; Conde, Jonas Nascimento; Józsi, Mihály; Isaac, Lourdes; Abreu, Patrícia Antônia Estima; Barbosa, Angela Silva

    2015-03-01

    Upon infection, pathogenic Leptospira species bind several complement regulators in order to overcome host innate immunity. We previously characterized a 20-kDa leptospiral surface protein which interacts with C4b binding protein (C4BP): leptospiral complement regulator-acquiring protein A (LcpA). Here we show that LcpA also interacts with human factor H (FH), which remains functionally active once bound to the protein. Antibodies directed against short consensus repeat 20 (SCR20) inhibited binding of FH to LcpA by approximately 90%, thus confirming that this particular domain is involved in the interaction. We have also shown for the first time that leptospires bind human vitronectin and that the interaction is mediated by LcpA. Coincubation with heparin blocked LcpA-vitronectin interaction in a dose-dependent manner, strongly suggesting that binding may occur through the heparin binding domains of vitronectin. LcpA also bound to the terminal pathway component C9 and inhibited Zn(2+)-induced polymerization and membrane attack complex (MAC) formation. Competitive binding assays indicated that LcpA interacts with C4BP, FH, and vitronectin through distinct sites. Taken together, our findings indicate that LcpA may play a role in leptospiral immune evasion. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  13. Heavy metals in surface sediments of the Jialu River, China: their relations to environmental factors.

    Science.gov (United States)

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-04-15

    This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    International Nuclear Information System (INIS)

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z.; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-01-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD Mn in water drove heavy metals to deposit in sediments. • B-IBI was sensitive to the adverse effect of heavy metals in sediments. - Abstract: This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community

  15. Aerosol surface area concentration: a governing factor in new particle formation in Beijing

    Directory of Open Access Journals (Sweden)

    R. Cai

    2017-10-01

    Full Text Available The predominating role of aerosol Fuchs surface area, AFuchs, in determining the occurrence of new particle formation (NPF events in Beijing was elucidated in this study. The analysis was based on a field campaign from 12 March to 6 April 2016 in Beijing, during which aerosol size distributions down to  ∼  1 nm and sulfuric acid concentrations were simultaneously monitored. The 26 days were classified into 11 typical NPF days, 2 undefined days, and 13 non-event days. A dimensionless factor, LΓ, characterized by the relative ratio of the coagulation scavenging rate over the condensational growth rate (Kuang et al., 2010, was applied in this work to reveal the governing factors for NPF events in Beijing. The three parameters determining LΓ are sulfuric acid concentration, the growth enhancement factor characterized by contribution of other gaseous precursors to particle growth, Γ, and AFuchs. Different from other atmospheric environments, such as in Boulder and Hyytiälä, the daily-maximum sulfuric acid concentration and Γ in Beijing varied in a narrow range with geometric standard deviations of 1.40 and 1.31, respectively. A positive correlation between the estimated new particle formation rate, J1.5, and sulfuric acid concentration was found with a mean fitted exponent of 2.4. However, the maximum sulfuric acid concentrations on NPF days were not significantly higher (even lower, sometimes than those on non-event days, indicating that the abundance of sulfuric acid in Beijing was high enough to initiate nucleation, but may not necessarily lead to NPF events. Instead, AFuchs in Beijing varied greatly among days with a geometric standard deviation of 2.56, whereas the variabilities of AFuchs in Tecamac, Atlanta, and Boulder were reported to be much smaller. In addition, there was a good correlation between AFuchs and LΓ in Beijing (R2 = 0.88. Therefore, it was AFuchs that fundamentally determined the occurrence of NPF events

  16. lnvestigation of Patch Coatings lnfluence on the Stress lntensity Factor for Surface Cracks

    DEFF Research Database (Denmark)

    Lambertsen, Søren Heide; Jepsen, Michael S.; Damkilde, Lars

    2013-01-01

    In this paper, it is investigated how a surface layer of epoxy glue will affect the crack propagation of a surface crack. The intension is to reduce or even stop the crack propagation by means of patch layer coating. When adding a patch layer to the surface with small cracks, the layer will attem...

  17. Heat capacity of ThO2

    International Nuclear Information System (INIS)

    Peng Shian

    1996-01-01

    The heat capacity C p of ThO 2 can be calculated as the phonon part of C p for other actinide dioxides used as fuel in nuclear reactors. Precise determination of the phonon part of C p of actinide dioxides is helpful to find out the contributions of other factors to C p . In this paper we have, through studying the heat capacity of ThO 2 , developed a general method applicable to the study of C p of other solids. In the developed method the three type -- different experimental measurements made on a solid-heat capacity, thermal expansion and Debye Waller factor -- can be brought together for comparison. The application of this method to the study of C p of ThO 2 has enabled us to propose a better description of C p of ThO 2 than the generally accepted expression

  18. Validation of surface crack stress intensity factors of a tubular K-joint

    International Nuclear Information System (INIS)

    Lie, S.T.; Lee, C.K.; Chiew, S.P.; Shao, Y.B.

    2005-01-01

    Tubular K-joints are encountered widely in offshore structures, and the prediction of damaged joints depends very much on the accuracy of stress intensity factor solutions (SIFs). No parametric equations and very few results have been proposed and published in the literature for estimating the SIFs of any K-joints subjected to complex loading conditions. In this paper, a mesh generation method proposed previously for the Y-joint and T-joint has been extended to the K-joint. This method is realized by dividing the K-joint into several sub-zones with each zone consisting of different types of elements and mesh densities. This method has a distinct advantage of controlling the mesh quality, and most importantly the aspect ratio of the elements along the crack front. When the mesh of all the sub-zones has been generated automatically and completely, they are merged to form the complete model. The two most commonly used methods, namely the J-integral and displacement extrapolation, are used to evaluate the SIF values along the crack front of a typical K-joint. To validate the accuracy of these computed SIFs, a full-scale K-joint specimen was tested to failure under fatigue loading conditions. The standard alternating current potential drop (ACPD) technique was used to monitor the rate of crack propagation of the surface crack located at the hot spot stress region. Using the given material parameters C and m, the experimental SIFs were deduced, and they are found to be in good agreement with the computed SIFs obtained from the generated models. Hence, the proposed finite element models are both efficient and reliable

  19. Effect of design factors on surface temperature and wear in disk brakes

    Science.gov (United States)

    Santini, J. J.; Kennedy, F. E.; Ling, F. F.

    1976-01-01

    The temperatures, friction, wear and contact conditions that occur in high energy disk brakes are studied. Surface and near surface temperatures were monitored at various locations in a caliper disk brake during drag type testing, with friction coefficient and wear rates also being determined. The recorded transient temperature distributions in the friction pads and infrared photographs of the rotor disk surface both showed that contact at the friction surface was not uniform, with contact areas constantly shifting due to nonuniform thermal expansion and wear. The effect of external cooling and of design modifications on friction, wear and temperatures was also investigated. It was found that significant decreases in surface temperature and in wear rate can be achieved without a reduction in friction either by slotting the contacting face of the brake pad or by modifying the design of the pad support to improve pad compliance. Both design changes result in more uniform contact conditions on the friction surface.

  20. Excitation of surface waves of ultracold neutrons on absorbing trap walls as anomalous loss factor

    International Nuclear Information System (INIS)

    Bokun, R.Ch.

    2006-01-01

    One analyzed probability of excitation of surface waves of ultracold neutrons in terms of a plane model consisting of three media: vacuum, a finite depth neutron absorbing substance layer and a neutron reflecting substrate. One demonstrated the absence of the mentioned surface waves in terms of the generally accepted model of two media: vacuum contiguous to the plane surface of a substance filled half-space. One pointed out the effect of the excited surface waves of ultracold neutrons on the increase of their anomalous losses in traps [ru

  1. Utilizing various data sources for surface transportation human factors research : workshop summary report, November 6-7, 2013

    Science.gov (United States)

    2014-07-01

    The report summarizes a 2-day workshop held on November 6-7, 2013, to discuss data sources for surface transportation human factors research. The workshop was designed to assess the increasing number of different datasets and multiple ways of collect...

  2. The use of simulated rainfall to study the discharge process and the influence factors of urban surface runoff pollution loads.

    Science.gov (United States)

    Qinqin, Li; Qiao, Chen; Jiancai, Deng; Weiping, Hu

    2015-01-01

    An understanding of the characteristics of pollutants on impervious surfaces is essential to estimate pollution loads and to design methods to minimize the impacts of pollutants on the environment. In this study, simulated rainfall equipment was constructed to investigate the pollutant discharge process and the influence factors of urban surface runoff (USR). The results indicated that concentrations of total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) appeared to be higher in the early period and then decreased gradually with rainfall duration until finally stabilized. The capacity and particle size of surface dust, rainfall intensity and urban surface slopes affected runoff pollution loads to a variable extent. The loads of TP, TN and COD showed a positive relationship with the surface dust capacity, whereas the maximum TSS load appeared when the surface dust was 0.0317 g·cm⁻². Smaller particle sizes (pollution carrying capacity of runoff, leading to higher pollution loads. Knowledge of the influence factors could assist in the management of USR pollution loads.

  3. Disorder in Ag{sub 7}GeSe{sub 5}I, a superionic conductor: temperature-dependent anharmonic structural study

    Energy Technology Data Exchange (ETDEWEB)

    Albert, S.; Pradel, A.; Ribes, M. [CNRS Montpellier Univ., 34 (France). Inst. Charles Gerhardt Montpellier; Pillet, S.; Lecomte, C. [CNRS Nancy Univ., 54 - Vandoeuvre-les-Nancy (France). Lab. de Cristallographie et de Modelisation des Materiaux Mineraux et Biologiques

    2008-02-15

    A temperature-dependent structural investigation of the substituted argyrodite Ag{sub 7}GeSe{sub 5}I has been carried out on a single crystal from 15 to 475 K, in steps of 50 K, and correlated to its conductivity properties. The argyrodite crystallizes in a cubic cell with the F anti 43m space group. The crystal structure exhibits high static and dynamic disorder which has been efficiently accounted for using a combination of (i) Gram- Charlier development of the Debye-Waller factors for iodine and silver, and (ii) a split-atom model for Ag{sup +} ions. An increased delocalization of the mobile d{sup 10} Ag{sup +} cations with temperature has been clearly shown by the inspection of the joint probability-density functions; the corresponding diffusion pathways have been determined. (orig.)

  4. Size-dependent penetrant diffusion in polymer glasses.

    Science.gov (United States)

    Meng, Dong; Zhang, Kai; Kumar, Sanat K

    2018-05-18

    Molecular Dynamics simulations are used to understand the underpinning basis of the transport of gas-like solutes in deeply quenched polymeric glasses. As found in previous work, small solutes, with sizes smaller than 0.15 times the chain monomer size, move as might be expected in a medium with large pores. In contrast, the motion of larger solutes is activated and is strongly facilitated by matrix motion. In particular, solute motion is coupled to the local elastic fluctuations of the matrix as characterized by the Debye-Waller factor. While similar ideas have been previously proposed for the viscosity of supercooled liquids above their glass transition, to our knowledge, this is the first illustration of this concept in the context of solute mass transport in deeply quenched polymer glasses.

  5. Phonons in Solid Hydrogen and Deuterium Studied by Inelastic Coherent Neutron Scattering

    DEFF Research Database (Denmark)

    Nielsen, Mourits

    1973-01-01

    Phonon dispersion relations have been measured by coherent neutron scattering in solid para-hydrogen and ortho-deuterium. The phonon energies are found to be nearly equal in the two solids, the highest energy in each case lying close to 10 meV. The pressure and temperature dependence of the phonon...... energies have been measured in ortho-deuterium and the lattice change determined by neutron diffraction. When a pressure of 275 bar is applied, the phonon energies are increased by about 10%, and heating the crystal to near the melting point decreases them by about 7%. The densities of states, the specific...... heats, and the Debye temperatures have been deduced and found to be in agreement with the published experimental results. The Debye temperatures are 118 K for hydrogen and 114 K for deuterium. For hydrogen the Debye-Waller factor has been measured by incoherent neutron scattering and it corresponds...

  6. Experimental signatures of a nonequilibrium phase transition governing the yielding of a soft glass.

    Science.gov (United States)

    Hima Nagamanasa, K; Gokhale, Shreyas; Sood, A K; Ganapathy, Rajesh

    2014-06-01

    We present direct experimental signatures of a nonequilibrium phase transition associated with the yield point of a prototypical soft solid-a binary colloidal glass. By simultaneously quantifying single-particle dynamics and bulk mechanical response, we identified the threshold for the onset of irreversibility with the yield strain. We extracted the relaxation time from the transient behavior of the loss modulus and found that it diverges in the vicinity of the yield strain. This critical slowing down is accompanied by a growing correlation length associated with the size of regions of high Debye-Waller factor, which are precursors to yield events in glasses. Our results affirm that the paradigm of nonequilibrium critical phenomena is instrumental in achieving a holistic understanding of yielding in soft solids.

  7. Higher-order glass-transition singularities in systems with short-ranged attractive potentials

    International Nuclear Information System (INIS)

    Goetze, W; Sperl, M

    2003-01-01

    Within the mode-coupling theory for the evolution of structural relaxation, the A 4 -glass-transition singularities are identified for systems of particles interacting with a hard-sphere repulsion complemented by different short-ranged potentials: Baxter's singular potential regularized by a large-wavevector cut-off, a model for the Asakura-Oosawa depletion attraction, a triangular potential, a Yukawa attraction, and a square-well potential. The regular potentials yield critical packing fractions, critical Debye-Waller factors, and critical amplitudes very close to each other. The elastic moduli and the particle localization lengths for corresponding states of the Yukawa system and the square-well system may differ by up to 20 and 10%, respectively

  8. First-principles study of crystalline and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} and the effects of stoichiometric defects

    Energy Technology Data Exchange (ETDEWEB)

    Caravati, S; Bernasconi, M [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via R Cozzi 53, I-20125, Milano (Italy); Kuehne, T D; Parrinello, M [Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Krack, M [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)], E-mail: marco.bernasconi@mater.unimib.it

    2009-06-24

    Based on ab initio molecular dynamics simulations, we investigated the structural, electronic and vibrational properties of cubic and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) phase change material, focusing in particular on the effects of defects in stoichiometry on the electronic properties. It turned out Ge/Sb deficiencies (excess) in the cubic phase induce a shift of the Fermi level inside the valence (conduction) bands. In contrast, the amorphous network is flexible enough to accommodate defects in stoichiometry, keeping the Fermi level pinned at the center of the bandgap (at zero temperature). Changes in the structural and electronic properties induced by the use of hybrid functionals (HSE03, PBE0) instead of gradient corrected functionals (PBE) are addressed as well. Analysis of vibrational spectra and Debye-Waller factors of cubic and amorphous GST is also presented.

  9. Structure analysis of NiAl martensite

    International Nuclear Information System (INIS)

    Noda, Y.; Shapiro, S.M.; Shirane, G.; Yamada, Y.; Fuchizaki, K.; Tanner, L.E.

    1989-01-01

    Neutron elastic scattering experiments were performed in order to investigate the structure of the low temperature martensitic phase of Ni 62.5 Al 37.5 alloy. The average structure analyzed from the integrated intensity was approximately described by the (5,-2) structure proposed by Martynov et al. Small deviation from the exact (5,-2) model in the positional parameters and the anomalously large Debye-Waller factor were obtained. The observed satellite profiles show asymmetrical broadening, and the peak positions shift from the regular reciprocal lattice points. These anomalous features of scattering profiles were tentatively interpreted by introducing spatial modulation of the strain and order parameters. 12 refs., 2 figs., 1 tab

  10. Pressure-induced positive electrical resistivity coefficient in Ni-Nb-Zr-H glassy alloy

    Science.gov (United States)

    Fukuhara, M.; Gangli, C.; Matsubayashi, K.; Uwatoko, Y.

    2012-06-01

    Measurements under hydrostatic pressure of the electrical resistivity of (Ni0.36Nb0.24Zr0.40)100-xHx (x = 9.8, 11.5, and 14) glassy alloys have been made in the range of 0-8 GPa and 0.5-300 K. The resistivity of the (Ni0.36Nb0.24Zr0.40)86H14 alloy changed its sign from negative to positive under application of 2-8 GPa in the temperature range of 300-22 K, coming from electron-phonon interaction in the cluster structure under pressure, accompanied by deformation of the clusters. In temperature region below 22 K, the resistivity showed negative thermal coefficient resistance by Debye-Waller factor contribution, and superconductivity was observed at 1.5 K.

  11. Low temperature features of the local structure of Sm1-xYxS

    International Nuclear Information System (INIS)

    Menushenkov, A. P.; Chernikov, R. V.; Sidorov, V. V.; Klementiev, K. V.; Alekseev, P. A.; Rybina, A. V.

    2007-01-01

    The particular features of the local electronic and local crystal structures of the mixed-valence compound Sm 1-x Y x S are studied by the XAFS spectroscopy methods in the temperature range 20-300 K for the yttrium concentration x = 0.17, 0.25, 0.33, and 0.45. The temperature behavior of the valence of Sm, as well as of the lengths and the Debye-Waller factors of the bonds Sm-S, Sm-Sm(Y), Y-S, and Y-Sm(Y), has been determined. The violation of the Vegard law has been observed. A model for the estimation of the energy width of the 4f level and of its position with respect to the Fermi level is proposed

  12. Neutron powder investigations of Zr0.85Ca0.15O1.85 sinter material at temperatures up to 1100 K and with a simultaneously applied electric field

    International Nuclear Information System (INIS)

    Kahlert, H.; Boysen, H.; Frey, F.

    1998-01-01

    In situ neutron powder investigations of cubic stabilized zirconia [Zr 0.85 Ca 0.15 O 1.85 (CSZ15)] sinter material were performed at room temperature without an applied direct-current electric field and at 1100 K with and without an applied field, i.e. lasting ionic current. Experimental conditions (temperature, oxidizing atmosphere etc.) were chosen as close as possible to 'working conditions' of zirconia oxygen sensoric devices. To learn about field-induced structural changes and most probable ionic pathways, atomic displacement parameters were derived in the frame of a non-Gaussian Debye-Waller factor formalism for the oxygens. Probability-density-function maps and pseudo-potential (V eff ) maps indicate curved diffusion pathways of the oxygens close to the left angle 100 right angle directions. The action of the applied field is to lower the effective potential barriers. (orig.)

  13. Electron-lattice energy relaxation in laser-excited thin-film Au-insulator heterostructures studied by ultrafast MeV electron diffraction.

    Science.gov (United States)

    Sokolowski-Tinten, K; Shen, X; Zheng, Q; Chase, T; Coffee, R; Jerman, M; Li, R K; Ligges, M; Makasyuk, I; Mo, M; Reid, A H; Rethfeld, B; Vecchione, T; Weathersby, S P; Dürr, H A; Wang, X J

    2017-09-01

    We apply time-resolved MeV electron diffraction to study the electron-lattice energy relaxation in thin film Au-insulator heterostructures. Through precise measurements of the transient Debye-Waller-factor, the mean-square atomic displacement is directly determined, which allows to quantitatively follow the temporal evolution of the lattice temperature after short pulse laser excitation. Data obtained over an extended range of laser fluences reveal an increased relaxation rate when the film thickness is reduced or the Au-film is capped with an additional insulator top-layer. This behavior is attributed to a cross-interfacial coupling of excited electrons in the Au film to phonons in the adjacent insulator layer(s). Analysis of the data using the two-temperature-model taking explicitly into account the additional energy loss at the interface(s) allows to deduce the relative strength of the two relaxation channels.

  14. Communication: Fast dynamics perspective on the breakdown of the Stokes-Einstein law in fragile glassformers.

    Science.gov (United States)

    Puosi, F; Pasturel, A; Jakse, N; Leporini, D

    2018-04-07

    The breakdown of the Stokes-Einstein (SE) law in fragile glassformers is examined by Molecular-Dynamics simulations of atomic liquids and polymers and consideration of the experimental data concerning the archetypical ortho-terphenyl glassformer. All the four systems comply with the universal scaling between the viscosity (or the structural relaxation) and the Debye-Waller factor ⟨u 2 ⟩, the mean square amplitude of the particle rattling in the cage formed by the surrounding neighbors. It is found that the SE breakdown is scaled in a master curve by a reduced ⟨u 2 ⟩. Two approximated expressions of the latter, with no and one adjustable parameter, respectively, are derived.

  15. Vibron Solitons and Soliton-Induced Infrared Spectra of Crystalline Acetanilide

    Science.gov (United States)

    Takeno, S.

    1986-01-01

    Red-shifted infrared spectra at low temperatures of amide I (C=O stretching) vibrations of crystalline acetanilide measured by Careri et al. are shown to be due to vibron solitons, which are nonlinearity-induced localized modes of vibrons arising from their nonlinear interactions with optic-type phonons. A nonlinear eigenvalue equation giving the eigenfrequency of stationary solitons is solved approximately by introducing lattice Green's functions, and the obtained result is in good agreement with the experimental result. Inclusion of interactions with acoustic phonons yields the Debye-Waller factor in the zero-phonon line spectrum of vibron solitons, in a manner analogous to the case of impurity-induced localized harmonic phonon modes in alkali halides.

  16. Moessbauer Studies of Implanted Impurities in Solids

    CERN Multimedia

    2002-01-01

    Moessbauer studies were performed on implanted radioactive impurities in semiconductors and metals. Radioactive isotopes (from the ISOLDE facility) decaying to a Moessbauer isotope were utilized to investigate electronic and vibrational properties of impurities and impurity-defect structures. This information is inferred from the measured impurity hyperfine interactions and Debye-Waller factor. In semiconductors isoelectronic, shallow and deep level impurities have been implanted. Complex impurity defects have been produced by the implantation process (correlated damage) or by recoil effects from the nuclear decay in both semiconductors and metals. Annealing mechanisms of the defects have been studied. \\\\ \\\\ In silicon amorphised implanted layers have been recrystallized epitaxially by rapid-thermal-annealing techniques yielding highly supersaturated, electrically-active donor concentrations. Their dissolution and migration mechanisms have been investigated in detail. The electronic configuration of Sb donors...

  17. Moessbauer spectroscopy of isotope separator implanted sup(119m)Sn in FCC metals

    International Nuclear Information System (INIS)

    Larsen, A.N.; Weyer, G.

    1979-01-01

    Radioactive sup(119m)Sn has been implanted in FCC metals by means of an isotope separator. Moessbauer spectra have been measured for the 24 keV transition of 119 Sn. Large substitutional fractions are found in all cases. A correlation for substitutional lattice sites between the measured isomer shifts of the impurity atoms and the force constants of the host lattices is discussed. Debye-Waller factors determined for substitutional Sn in the host lattices are found to be smaller than values calculated by a simple mass-defect model. For some host metals indications of an influence of radiation damage on the spectra are observed. Defect sites are assigned to Sn in aluminium and lead. Qualitative conclusions on the structures of these defects are drawn from the determined Moessbauer parameters. (author)

  18. High pressure and high temperature EXAFS and diffraction study of AgI

    International Nuclear Information System (INIS)

    Yoshiasa, Akira; Arima, Hiroshi; Fukui, Hiroshi; Okube, Maki; Katayama, Yoshinori; Ohtaka, Osamu

    2009-01-01

    We have determined the precise P-T phase diagram of AgI by in-situ high-pressure high-temperature synchrotron experiments. X-ray diffraction and XAFS measurements were performed up to 6.0 GPa and 1100 K using a multi-anvil high-pressure device and synchrotron radiation from SPring-8. In the disordered rock-salt phase, Ag ions occupy both octahedral and tetrahedral sites and twenty percent of Ag ions occupy the tetrahedral site as a maximum value at 2 GPa. From the viewpoint of the local structure analyses, some sudden changes are recognized near broad phase transition point. Analysis of EXAFS Debye-Waller factor is useful because the force constant can be decided directly even at high pressure and high temperature. Pressure influences greatly the effective potential and anharmonicity decreases with increasing pressure. (author)

  19. Neutral Silicon-Vacancy Center in Diamond: Spin Polarization and Lifetimes

    Science.gov (United States)

    Green, B. L.; Mottishaw, S.; Breeze, B. G.; Edmonds, A. M.; D'Haenens-Johansson, U. F. S.; Doherty, M. W.; Williams, S. D.; Twitchen, D. J.; Newton, M. E.

    2017-09-01

    We demonstrate optical spin polarization of the neutrally charged silicon-vacancy defect in diamond (SiV0 ), an S =1 defect which emits with a zero-phonon line at 946 nm. The spin polarization is found to be most efficient under resonant excitation, but nonzero at below-resonant energies. We measure an ensemble spin coherence time T2>100 μ s at low-temperature, and a spin relaxation limit of T1>25 s . Optical spin-state initialization around 946 nm allows independent initialization of SiV0 and NV- within the same optically addressed volume, and SiV0 emits within the telecoms down-conversion band to 1550 nm: when combined with its high Debye-Waller factor, our initial results suggest that SiV0 is a promising candidate for a long-range quantum communication technology.

  20. Radiation damage in A-15 materials: EXAFS studies

    International Nuclear Information System (INIS)

    Knapp, G.S.; Kampwirth, R.T.; Georgopoulos, P.; Brown, B.S.

    1980-01-01

    EXAFS measurements are useful in determining the local atomic environment of a particular element in a solid. Since there has been some controversy about the nature of the defects produced in A-15 materials by radiation damage, such studies were carried out on some A-15 compounds, V 3 Ga which was damaged by neutrons, as well as Nb 3 Ge damaged by 2.5 MeV a particles. In the V 3 Ga sample, site exchange disorder seems to be the most important result of the neutron damage with less than 20% of the vanadium atoms on wrong sites. However, in the Nb 3 Ge samples in addition to site exchange disorder, an unusual splitting of the first near-neighbor distance between the Ge and Nb is found. This splitting, approximately 0.2 A, may explain the large Debye Waller factors observed by Burbank et al

  1. Factors affecting projected Arctic surface shortwave heating and albedo change in coupled climate models.

    Science.gov (United States)

    Holland, Marika M; Landrum, Laura

    2015-07-13

    We use a large ensemble of simulations from the Community Earth System Model to quantify simulated changes in the twentieth and twenty-first century Arctic surface shortwave heating associated with changing incoming solar radiation and changing ice conditions. For increases in shortwave absorption associated with albedo reductions, the relative influence of changing sea ice surface properties and changing sea ice areal coverage is assessed. Changes in the surface sea ice properties are associated with an earlier melt season onset, a longer snow-free season and enhanced surface ponding. Because many of these changes occur during peak solar insolation, they have a considerable influence on Arctic surface shortwave heating that is comparable to the influence of ice area loss in the early twenty-first century. As ice area loss continues through the twenty-first century, it overwhelms the influence of changes in the sea ice surface state, and is responsible for a majority of the net shortwave increases by the mid-twenty-first century. A comparison with the Arctic surface albedo and shortwave heating in CMIP5 models indicates a large spread in projected twenty-first century change. This is in part related to different ice loss rates among the models and different representations of the late twentieth century ice albedo and associated sea ice surface state. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  2. Semiconductor Sensors Application for Definition of Factor of Ozone Heterogeneous Destruction on Teflon Surface

    Directory of Open Access Journals (Sweden)

    Nataliya V. Finogenova

    2003-12-01

    Full Text Available In our paper we present the results of our research, which was carried out by means of semiconductor sensor techniques (SCS, which allowed evaluating heterogeneous death-rate of ozone (γ Teflon surface. When ozone concentration is near to Ambient Air Standard value, γ is assessed to be equal to 6,57*10-7. High technique response provide possibility to determine ozone contents in the air media and the percentage of ozone, decomposed on the communication surfaces and on the surfaces of installation in the low concentration range (1–100 ppb.

  3. Design of an electrochemical cell for in situ XAS studies

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, N. [Instituto de Quimica, Universidade Estadual de Campinas (UNICAMP), Box 6154, CEP 13083-970, Campinas, SP (Brazil); Morais, J. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15051, CEP 91501-970, Porto Alegre, RS (Brazil); Alves, M.C.M. [Instituto de Quimica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15003, CEP 91501-970, Porto Alegre, RS (Brazil)], E-mail: maria@iq.ufrgs.br

    2007-05-15

    In situ X-ray absorption spectroscopy (XAS) studies have been carried out on the electrochemical insertion of Co metal particles in polypyrrole. This has become possible due to the development of an electrochemical cell to allow XAS studies in fluorescence geometry under steady-state conditions. The experimental set-up allows the in situ monitoring of the structural and electronic changes of the selected atom in a matrix. The project of the electrochemical cell is presented with the results obtained at different stages of the electrochemical process. XANES and EXAFS results showed that the initial stage of the cobalt insertion in polypyrrole took place in an ionic form, like [-[(C{sub 4}H{sub 2}N){sub 3}CH{sub 3}(CH{sub 2}){sub 11}OSO{sub 3}{sup -}]{sub 6}Co{sup 2+}] with posterior reduction to a metallic form. The quantitative analysis of the first shell shows that, at -0.60 V, the cobalt atoms are surrounded by 6 ({+-}0.5) atoms located at 2.12 ({+-}0.05) A with a large Debye-Waller factor ({sigma}{sup 2}) value of 0.0368 ({+-}0.0074). At -0.80 V, two distances of R = 1.99 ({+-}0.01) and R = 2.50 ({+-}0.01) A show the coexistence of cobalt in the oxidized and reduced (Co{sup 0}) forms. The Co-Co distance corresponds to that of bulk cobalt. At -1.20 V, the obtained values of N = 12 ({+-}0.5) and R = 2.56 ({+-}0.01) A and a Debye-Waller factor of 0.0176 ({+-}0.0004) suggest the formation of metallic cobalt in a quite disordered form.

  4. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, K. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Fazal-ur-Rehman [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Ali, S. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Khan, H.A. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group

    1997-03-21

    In the field of radon dosimetry, it is customary to measure radon ({sup 222}Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon`s progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.).

  5. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    International Nuclear Information System (INIS)

    Jamil, K.; Fazal-ur-Rehman; Ali, S.; Khan, H.A.

    1997-01-01

    In the field of radon dosimetry, it is customary to measure radon ( 222 Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon's progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.)

  6. Computer-aided study of key factors determining high mechanical properties of nanostructured surface layers in metal-ceramic composites

    Science.gov (United States)

    Konovalenko, Igor S.; Shilko, Evgeny V.; Ovcharenko, Vladimir E.; Psakhie, Sergey G.

    2017-12-01

    The paper presents the movable cellular automaton method. It is based on numerical models of surface layers of the metal-ceramic composite NiCr-TiC modified under electron beam irradiation in inert gas plasmas. The models take into account different geometric, concentration and mechanical parameters of ceramic and metallic components. The authors study the contributions of key structural factors in mechanical properties of surface layers and determine the ranges of their variations by providing the optimum balance of strength, strain hardening and fracture toughness.

  7. Efficient computer program EPAS-J1 for calculating stress intensity factors of three-dimensional surface cracks

    International Nuclear Information System (INIS)

    Miyazaki, Noriyuki; Watanabe, Takayuki; Yagawa, Genki.

    1982-03-01

    A finite element computer program EPAS-J1 was developed to calculate the stress intensity factors of three-dimensional cracks. In the program, the stress intensity factor is determined by the virtual crack extension method together with the distorted elements allocated along the crack front. This program also includes the connection elements based on the Lagrange multiplier concept to connect such different kinds of elements as the solid and shell elements, or the shell and beam elements. For the structure including three-dimensional surface cracks, the solid elements are employed only at the neighborhood of a surface crack, while the remainder of the structure is modeled by the shell or beam elements due to the reason that the crack singularity is very local. Computer storage and computational time can be highly reduced with the application of the above modeling technique for the calculation of the stress intensity factors of the three-dimensional surface cracks, because the three-dimensional solid elements are required only around the crack front. Several numerical analyses were performed by the EPAS-J1 program. At first, the accuracies of the connection element and the virtual crack extension method were confirmed using the simple structures. Compared with other techniques of connecting different kinds of elements such as the tying method or the method using anisotropic plate element, the present connection element is found to provide better results than the others. It is also found that the virtual crack extension method provides the accurate stress intensity factor. Furthermore, the results are also presented for the stress intensity factor analyses of cylinders with longitudinal or circumferential surface cracks using the combination of the various kinds of elements together with the connection elements. (author)

  8. The Path to High Q-Factors in Superconducting Accelerating Cavities: Flux Expulsion and Surface Resistance Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Martinello, Martina [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-12-01

    Accelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators. Superconducting accelerating cavities are made out of niobium and operate at the liquid helium temperature. Even if superconducting, these resonating structures have some RF driven surface resistance that causes power dissipation. In order to decrease as much as possible the power losses, the cavity quality factor must be increased by decreasing the surface resistance. In this dissertation, the RF surface resistance is analyzed for a large variety of cavities made with different state-of-the-art surface treatments, with the goal of finding the surface treatment capable to return the highest Q-factor values in a cryomodule-like environment. This study analyzes not only the superconducting properties described by the BCS surface resistance, which is the contribution that takes into account dissipation due to quasi-particle excitations, but also the increasing of the surface resistance due to trapped flux. When cavities are cooled down below their critical temperature inside a cryomodule, there is always some remnant magnetic field that may be trapped increasing the global RF surface resistance. This thesis also analyzes how the fraction of external magnetic field, which is actually trapped in the cavity during the cooldown, can be minimized. This study is performed on an elliptical single-cell horizontally cooled cavity, resembling the geometry of cavities cooled in accelerator cryomodules. The horizontal cooldown study reveals that, as in case of the vertical cooldown, when the cooling is performed fast, large thermal gradients are created along the cavity helping magnetic flux expulsion. However, for this geometry the complete magnetic flux expulsion from the cavity equator is more difficult to achieve. This becomes even more challenging in presence of orthogonal magnetic field, that is easily trapped on top of the cavity equator

  9. The path to high Q-factors in superconducting accelerating cavities: Flux expulsion and surface resistance optimization

    Science.gov (United States)

    Martinello, Martina

    Accelerating cavities are devices resonating in the radio-frequency (RF) range used to accelerate charged particles in accelerators. Superconducting accelerating cavities are made out of niobium and operate at the liquid helium temperature. Even if superconducting, these resonating structures have some RF driven surface resistance that causes power dissipation. In order to decrease as much as possible the power losses, the cavity quality factor must be increased by decreasing the surface resistance. In this dissertation, the RF surface resistance is analyzed for a large variety of cavities made with different state-of-the-art surface treatments, with the goal of finding the surface treatment capable to return the highest Q-factor values in a cryomodule-like environment. This study analyzes not only the superconducting properties described by the BCS surface resistance, which is the contribution that takes into account dissipation due to quasi-particle excitations, but also the increasing of the surface resistance due to trapped flux. When cavities are cooled down below their critical temperature inside a cryomodule, there is always some remnant magnetic field that may be trapped increasing the global RF surface resistance. This thesis also analyzes how the fraction of external magnetic field, which is actually trapped in the cavity during the cooldown, can be minimized. This study is performed on an elliptical single-cell horizontally cooled cavity, resembling the geometry of cavities cooled in accelerator cryomodules. The horizontal cooldown study reveals that, as in case of the vertical cooldown, when the cooling is performed fast, large thermal gradients are created along the cavity helping magnetic flux expulsion. However, for this geometry the complete magnetic flux expulsion from the cavity equator is more difficult to achieve. This becomes even more challenging in presence of orthogonal magnetic field, that is easily trapped on top of the cavity equator

  10. Influence of Ecological Factors on Estimation of Impervious Surface Area Using Landsat 8 Imagery

    Directory of Open Access Journals (Sweden)

    Yuqiu Jia

    2017-07-01

    Full Text Available Estimation of impervious surface area is important to the study of urban environments and social development, but surface characteristics, as well as the temporal, spectral, and spatial resolutions of remote sensing images, influence the estimation accuracy. To investigate the effects of regional environmental characteristics on the estimation of impervious surface area, we divided China into seven sub-regions based on climate, soil type, feature complexity, and vegetation phenology: arid and semi-arid areas, Huang-Huai-Hai winter wheat production areas, typical temperate regions, the Pearl River Delta, the middle and lower reaches of the Yangtze River, typical tropical and subtropical regions, and the Qinghai Tibet Plateau. Impervious surface area was estimated from Landsat 8 images of five typical cities, including Yinchuan, Shijiazhuang, Shenyang, Ningbo, and Kunming. Using the linear spectral unmixing method, impervious and permeable surface areas were determined at the pixel-scale based on end-member proportions. We calculated the producer’s accuracy, user’s accuracy, and overall accuracy to assess the estimation accuracy, and compared the accuracies among images acquired from different seasons and locations. In tropical and subtropical regions, vegetation canopies can confound the identification of impervious surfaces and, thus, images acquired in winter, early spring, and autumn are most suitable; estimations in the Pearl River Delta, the middle and lower reaches of the Yangtze River are influenced by soil, vegetation phenology, vegetation canopy, and water, and images acquired in spring, summer, and autumn provide the best results; in typical temperate areas, images acquired from spring to autumn are most effective for estimations; in winter wheat-growing areas, images acquired throughout the year are suitable; and in arid and semi-arid areas, summer and early autumn, during which vegetation is abundant, are the optimal seasons for

  11. The impact of climatic and non-climatic factors on land surface temperature in southwestern Romania

    Science.gov (United States)

    Roşca, Cristina Florina; Harpa, Gabriela Victoria; Croitoru, Adina-Eliza; Herbel, Ioana; Imbroane, Alexandru Mircea; Burada, Doina Cristina

    2017-11-01

    Land surface temperature is one of the most important parameters related to global warming. It depends mainly on soil type, discontinuous vegetation cover, or lack of precipitation. The main purpose of this paper is to investigate the relationship between high LST, synoptic conditions and air masses trajectories, vegetation cover, and soil type in one of the driest region in Romania. In order to calculate the land surface temperature and normalized difference vegetation index, five satellite images of LANDSAT missions 5 and 7, covering a period of 26 years (1986-2011), were selected, all of them collected in the month of June. The areas with low vegetation density were derived from normalized difference vegetation index, while soil types have been extracted from Corine Land Cover database. HYSPLIT application was employed to identify the air masses origin based on their backward trajectories for each of the five study cases. Pearson, logarithmic, and quadratic correlations were used to detect the relationships between land surface temperature and observed ground temperatures, as well as between land surface temperature and normalized difference vegetation index. The most important findings are: strong correlation between land surface temperature derived from satellite images and maximum ground temperature recorded in a weather station located in the area, as well as between areas with land surface temperature equal to or higher than 40.0 °C and those with lack of vegetation; the sandy soils are the most prone to high land surface temperature and lack of vegetation, followed by the chernozems and brown soils; extremely severe drought events may occur in the region.

  12. Examining factors that influence the effectiveness of cleaning antineoplastic drugs from drug preparation surfaces: a pilot study.

    Science.gov (United States)

    Hon, Chun-Yip; Chua, Prescillia Ps; Danyluk, Quinn; Astrakianakis, George

    2014-06-01

    Occupational exposure to antineoplastic drugs has been documented to result in various adverse health effects. Despite the implementation of control measures to minimize exposure, detectable levels of drug residual are still found on hospital work surfaces. Cleaning these surfaces is considered as one means to minimize the exposure potential. However, there are no consistent guiding principles related to cleaning of contaminated surfaces resulting in hospitals to adopt varying practices. As such, this pilot study sought to evaluate current cleaning protocols and identify those factors that were most effective in reducing contamination on drug preparation surfaces. Three cleaning variables were examined: (1) type of cleaning agent (CaviCide®, Phenokil II™, bleach and chlorhexidine), (2) application method of cleaning agent (directly onto surface or indirectly onto a wipe) and (3) use of isopropyl alcohol after cleaning agent application. Known concentrations of antineoplastic drugs (either methotrexate or cyclophosphamide) were placed on a stainless steel swatch and then, systematically, each of the three cleaning variables was tested. Surface wipes were collected and quantified using high-performance liquid chromatography-tandem mass spectrometry to determine the percent residual of drug remaining (with 100% being complete elimination of the drug). No one single cleaning agent proved to be effective in completely eliminating all drug contamination. The method of application had minimal effect on the amount of drug residual. In general, application of isopropyl alcohol after the use of cleaning agent further reduced the level of drug contamination although measureable levels of drug were still found in some cases.

  13. The effect of ozone and open air factor on surface-attached and biofilm environmental Listeria monocytogenes.

    Science.gov (United States)

    Nicholas, R; Dunton, P; Tatham, A; Fielding, L

    2013-08-01

    The effects of gaseous ozone and open air factor (OAF) on environmental Listeria monocytogenes attached to three common food contact surfaces were investigated. Listeria monocytogenes on different food contact surfaces was treated with ozone and OAF. Microbiological counts, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were performed. Ozone at 10 ppm gave <1-log reduction when L. monocytogenes was attached to stainless steel, while 45 ppm gave a log reduction of 3.41. OAF gave better log reductions than 10 ppm ozone, but lower log reductions than 45 ppm. Significant differences were found between surfaces. Biofilm organisms were significantly more resistant than those surface attached on stainless steel. SEM and AFM demonstrated different membrane and cell surface modifications following ozone or OAF treatment. The strain used demonstrated higher resistance to ozone than previous studies. This may be due to the fact that it was isolated from a food manufacturing premises that used oxidizing disinfectants. OAF was more effective at reducing the levels of the organism than an ozone concentration of 10 ppm. Pathogen management strategies must account for resistance of environmental strains when validating cleaning and disinfection. OAF has shown potential for surface decontamination compared with ozone. SEM and AFM are valuable tools for determining mechanisms of action of antimicrobial agents. © 2013 The Society for Applied Microbiology.

  14. Summer U.S. Surface Air Temperature Variability: Controlling Factors and AMIP Simulation Biases

    Science.gov (United States)

    Merrifield, A.; Xie, S. P.

    2016-02-01

    This study documents and investigates biases in simulating summer surface air temperature (SAT) variability over the continental U.S. in the Coupled Model Intercomparison Project (CMIP5) Atmospheric Model Intercomparison Project (AMIP). Empirical orthogonal function (EOF) and multivariate regression analyses are used to assess the relative importance of circulation and the land surface feedback at setting summer SAT over a 30-year period (1979-2008). In observations, regions of high SAT variability are closely associated with midtropospheric highs and subsidence, consistent with adiabatic theory (Meehl and Tebaldi 2004, Lau and Nath 2012). Preliminary analysis shows the majority of the AMIP models feature high SAT variability over the central U.S., displaced south and/or west of observed centers of action (COAs). SAT COAs in models tend to be concomitant with regions of high sensible heat flux variability, suggesting an excessive land surface feedback in these models modulate U.S. summer SAT. Additionally, tropical sea surface temperatures (SSTs) play a role in forcing the leading EOF mode for summer SAT, in concert with internal atmospheric variability. There is evidence that models respond to different SST patterns than observed. Addressing issues with the bulk land surface feedback and the SST-forced component of atmospheric variability may be key to improving model skill in simulating summer SAT variability over the U.S.

  15. Assessment of Environmental Factors of Geology on Waste and Engineering Barriers for Waste Storage Near Surface

    International Nuclear Information System (INIS)

    Arimuladi SP

    2007-01-01

    Geological environment factors include features and processes occurring within that spatial and temporal (post-closure) domain whose principal effect is to determine the evolution of the physical, chemical, biological and human conditions of the domain that are relevant to estimating the release and migration of radionuclide and consequent exposure to man. Hardness of radioactive waste and engineer barrier can be decrease by environmental factors. Disposal system domain geological environment factors is a category in the International FEP list and is divided into sub-categories. There are 13 sub-factors of geological environment, 12 sub-factors influence hardness of radioactive waste and engineer barrier, thermal processes and conditions in geosphere can be excluded. (author)

  16. Influence of Urbanization Factors on Surface Urban Heat Island Intensity: A Comparison of Countries at Different Developmental Phases

    Directory of Open Access Journals (Sweden)

    Yaoping Cui

    2016-07-01

    Full Text Available Urbanization is a global problem with demographic trends. The urban heat island plays a dominant role in local climate systems. Despite existing efforts to understand the impacts of multiple urbanization factors on the urban heat island globally, very little is known about the attribution of urban heat island magnitude to urbanization in different locations or developmental phases. In this study, based on global land surface temperature data, urban spatial domain data, gross domestic product (GDP, and population data, we analyzed the influence of multiple urbanization factors on global surface urban heat island intensity (SUHII. We also tentatively compared the abovementioned factors between different regions across the globe, especially between China and the USA, the largest countries that are experiencing or have experienced rapid urbanization in recent decades. The results showed that global SUHII had remarkable spatial heterogeneity due to the geographical and socioeconomic variation between cities. There was a significant correlation between SUHII and population as well as GDP in global cities. Moreover, this study suggested that the impacts of population on SUHII might be stronger in the early stages of urbanization, and the GDP factor would become a critical factor at a certain development level. The urban area also had non-ignorable impacts on SUHII, while the correlation between SUHII and urban shape was relatively weak. All these may imply that the best approach to slow down SUHII is to find other solutions, e.g., optimize the spatial configuration of urban internal landscapes, when the urbanization reaches a high level.

  17. Shielding factors for vehicles to gamma radiation from activity deposited on structures and ground surfaces

    International Nuclear Information System (INIS)

    Lauridsen, B.; Hedemann Jensen, P.

    1982-04-01

    This report describes a measuring procedure for the determination of shielding factors for vehicles passing through areas that have been contaminated by activity released to the atmosphere from a reactor accident. A simulated radiation field from fallout has been approximated by a point source that has been placed in a matrix around and above the vehicle. Modifying factors are discussed such as mutual shielding by nearby buildings and passengers. From measurements on different vehicles with and without passengers shielding factors are recommended for ordinary cars and busses in both urban and open areas, and areas with single family houses. (author)

  18. Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Yinhuan Ao

    2017-01-01

    Full Text Available This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT, net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1 affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL, (2 deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3 the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4 integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5 the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude.

  19. Flow analysis of water-powder mixtures: Application to specific surface area and shape factor

    NARCIS (Netherlands)

    Hunger, M.; Brouwers, H.J.H.

    2009-01-01

    This paper addresses the characterization of powder materials with respect to their application in concrete. Given that powders provide by far highest percentage of specific surface area in a concrete mix, their packing behavior and water demand is of vital interest for the design of concrete. They

  20. Flow analysis of water-powder mixtures : Application to specific surface area and shape factor

    NARCIS (Netherlands)

    Hunger, M.; Brouwers, H.J.H.

    2009-01-01

    This paper addresses the characterization of powder materials with respect to their application in concrete. Given that powders provide by far highest percentage of specific surface area in a concrete mix, their packing behavior and water demand is of vital interest for the design of concrete. They

  1. Physicochemical factors influencing bacterial transfer from contact lenses to surfaces with different roughness and wettability.

    Science.gov (United States)

    Vermeltfoort, Pit B J; van der Mei, Henny C; Busscher, Henk J; Hooymans, Johanna M M; Bruinsma, Gerda M

    2004-11-15

    The aim of this study was to determine the transfer of Pseudomonas aeruginosa No. 3 and Staphylococcus aureus 835 from contact lenses to surfaces with different hydrophobicity and roughness. Bacteria were allowed to adhere to contact lenses (Surevue, PureVision, or Focus Night & Day) by incubating the lenses in a bacterial suspension for 30 min. The contaminated lenses were put on a glass, poly(methylmethacrylate), or silicone rubber substratum, shaped to mimic the eye. After 2 and 16 h, lenses were separated from the substrata and bacteria were swabbed off from the respective surfaces and resuspended in saline. Appropriate serial dilutions of these suspensions were made, from which aliquots were plated on agar for enumeration. Bacterial transfer varied between 4 and 60%, depending on the combination of strain, contact time, contact lens, and substratum surface. For P. aeruginosa No. 3, transfer was significantly higher after 16 h than after 2 h, whereas less increase with time was seen for S. aureus 835. Bacterial transfer from all tested contact lenses was least to silicone rubber, the most hydrophobic and roughest substratum surface included. (c) 2004 Wiley Periodicals, Inc.

  2. Physicochernical factors influencing bacterial transfer from contact lenses to surfaces with different roughness and Wettability

    NARCIS (Netherlands)

    Vermeltfoort, PBJ; van der Mei, HC; Busscher, HJ; Hooymans, JMM; Bruinsma, GM

    2004-01-01

    The aim of this study was to determine the transfer of Pseudomonas aeruginosa No. 3 and Staphylococcus aureus 835 from contact lenses to surfaces with different hydrophobicity and roughness. Bacteria were allowed to adhere to contact lenses (Surevue, PureVision, or Focus Night & Day) by incubating

  3. Factors governing particulate corrosion product adhesion to surfaces in water reactor coolant circuits

    International Nuclear Information System (INIS)

    1979-03-01

    Gravity, van der Waals, magnetic, electrical double layer and hydrodynamic forces are considered as potential contributors to the adhesion of particulate corrosion products to surfaces in water reactor coolant circuits. These forces are renewed and evaluated, and the following are amongst the conclusions drawn; adequate theories are available to estimate the forces governing corrosion product particle adhesion to surfaces in single phase flow in water reactor coolant circuits. Some uncertainty is introduced by the geometry of real particle-surface systems. The major uncertainties are due to inadequate data on the Hamaker constant and the zeta potential for the relevant materials, water chemistry and radiation chemistry at 300 0 C; van der Waals force is dominant over the effect of gravity for particles smaller than about 100 m; quite modest zeta potentials, approximately 50mV, are capable of inhibiting particle deposition throughout the size range relevant to water reactors; for surfaces exposed to typical water reactor flow conditions, particles smaller than approximately 1 m will be stable against resuspension in the absence of electrical double layer repulsion; and the magnitude of the electrical double layer repulsion for a given potential depends on whether the interaction is assumed to occur at constant potential or constant change. (author)

  4. Determination of friction factors and heat transfer coefficients for flow past artificially roughened surfaces

    International Nuclear Information System (INIS)

    Hodge, S.A.

    1979-12-01

    Because convective heat transfer is enhanced in flow past rough surfaces, much experimental and analytical effort over the past several decades has been devoted to the evaluation of artificial roughening for potential application to the heat transfer surfaces of gas-cooled reactors. Unfortunately, much of the analytical development in this field has been inadequately explained in the literature; this has led to misinterpretation of some of the subsequent experimental findings, compounding the uncertainty. This work provides a critical review of the underlying assumptions, theoretical foundations, and supporting experimental evidence for the analytical procedures in current use for the evaluation of roughness effects. It is a concise presentation of the available formulations with recommendations concerning their applicability to rough rod bundles

  5. Mesh construction and evaluation of the stress intensity factor for the semi-elliptical surface cracks

    International Nuclear Information System (INIS)

    Kim, Jong Wook; Lee, Gyu Mahn; Jeong, Kyeong Hoon; Kim, Tae Wan; Park, Keun Bae

    2001-01-01

    As actual cracks found in practical structures are mostly three-dimensional surface cracks, such cracks give rise to the important problem when the structural integrity is evaluated in a viewpoint of fracture mechanics. The case of a semi-elliptical surface crack is more complicated than that of the embedded elliptical crack since the crack front intersects the free surface. Therefore, the exact expression of stress field according to the boundary condition can be the prior process for the structural integrity evaluation . The commercial code, I-DEAS does not provide the family of strain singular element for the cracked-body analysis. This means that the user cannot make use of the pre-processing function of I-DEAS effectively. But I-DEAS has the capability to hold input data in common with computational fracture mechanics program like ABAQUS. Hence, user can construct the optimized analysis method for the generation of input data of program like ABAQUS using the I-DEAS. In the present study, a procedure for the generation of input data for the optimized 3-dimensional computational fracture mechanics is developed as a series of effort to establish the structural integriyt evaluation procedure of SMART reactor vessel assembly. Input data for the finite element analysis are made using the commercial code, I-DEAS program, The stress analysis is performed using the ABAQUS. To demonstrate the validation of the developed procedure in the present sutdy, semi-elliptic surface crack in a half space subjected to uniform tension are solved, and the effects of crack configuration ratio are discussed in detail. The numerical results are presented and compared to those presented by Raju and Newman. Also, we have established the structural integrity evaluation procedure through the 3-D crack modeling

  6. Analytical prediction of friction factors and Nusselt numbers of turbulent forced convection in rod bundles with smooth and rough surfaces

    International Nuclear Information System (INIS)

    Su Jian; Silva Freire, Atila P.

    2002-01-01

    A simple analytical method was developed for the prediction of the friction factor, f, of fully developed turbulent flow and the Nusselt number, Nu, of fully developed turbulent forced convection in rod bundles arranged in square or hexagonal arrays. The friction factor equation for smooth rod bundles was presented in a form similar to the friction factor equation for turbulent flow in a circular pipe. An explicit equation for the Nusselt number of turbulent forced convection in rod bundles with smooth surface was developed. In addition, we extended the analysis to rod bundles with rough surface and provided a method for the prediction of the friction factor and the Nusselt number. The method was based on the law of the wall for velocity and the law of the wall for the temperature, which were integrated over the entire flow area to yield algebraic equations for the prediction of f and Nu. The present method is applicable to infinite rod bundles in square and hexagonal arrays with low pitch to rod diameter ratio, P/D<1.2

  7. Dynamic factor modeling of ground and surface water levels in an agricultural area adjacent to Everglades National Park

    Science.gov (United States)

    Ritter, A.; Muñoz-Carpena, R.

    2006-02-01

    The extensive eastern boundary of Everglades National Park (ENP) in south Florida (USA) is subject to one the most expensive and ambitious environmental restoration projects in history. Understanding and predicting the interaction between the shallow aquifer and surface water is a key component for fine-tuning the process. The Frog Pond is an intensively instrumented agricultural 2023 ha area adjacent to ENP. The interactions among 21 multivariate daily time series (ground and surface water elevations, rainfall and evapotranspiration) available from this area were studied by means of dynamic factor analysis, a novel technique in the field of hydrology. This method is designed to determine latent or background effects governing variability or fluctuations in non-stationary time series. Water levels in 16 wells and two drainage ditch locations inside the area were selected as response variables, and canal levels and net recharge as explanatory variables. Elevations in the two canals delimiting the Frog Pond area were found to be the main factors explaining the response variables. This influence of canal elevations on water levels inside the area was complementary and inversely related to the distance between the observation point and each canal. Rainfall events do not affect daily water levels significantly but are responsible for instantaneous or localized groundwater responses that in some cases can be directly associated with the risk of flooding. This close coupling between surface and groundwater levels, that corroborates that found by other authors using different methods, could hinder on-going environmental restoration efforts in the area by bypassing the function of wetlands and other surface features. An empirical model with a reduced set of parameters was successfully developed and validated in the area by interpolating the results from the dynamic factor analysis across the spatial domain (coefficient of efficiency across the domain: 0.66-0.99). Although

  8. The interplay between surfaces and soluble factors define the immunologic and angiogenic properties of myeloid dendritic cells

    Directory of Open Access Journals (Sweden)

    Mansfield Kristen

    2011-06-01

    Full Text Available Abstract Background Dendritic cells (DCs are antigen presenting cells capable of inducing specific immune responses against microbial infections, transplant antigens, or tumors. Interestingly, microenvironment conditions such as those present in tumor settings might induce a DC phenotype that is poorly immunogenic and with the capability of promoting angiogenesis. We hypothesize that this plasticity may be caused not only by the action of specific cytokines or growth factors but also by the properties of the surfaces with which they interact, such as extracellular matrix (ECM components. Results Herewith we studied the effect of different surfaces and soluble factors on the biology of DCs. To accomplish this, we cultured murine myeloid(m DCs on surfaces coated with fibronectin, collagen I, gelatin, and Matrigel using poly-D-lysine and polystyrene as non-biological surfaces. Further, we cultured these cells in the presence of regular DC medium (RPMI 10% FBS or commercially available endothelial medium (EGM-2. We determined that mDCs could be kept in culture up to 3 weeks in these conditions, but only in the presence of GM-CSF. We were able to determine that long-term DC cultures produce an array of angiogenic factors, and that some of these cultures still retain the capability to induce T cell responses. Conclusions Altogether these data indicate that in order to design DC-based vaccines or treatments focused on changing the phenotype of DCs associated with diseases such as cancer or atherosclerosis, it becomes necessary to fully investigate the microenvironment in which these cells are present or will be delivered.

  9. The surface chemistry of sapphire-c: A literature review and a study on various factors influencing its IEP.

    Science.gov (United States)

    Lützenkirchen, J; Franks, G V; Plaschke, M; Zimmermann, R; Heberling, F; Abdelmonem, A; Darbha, G K; Schild, D; Filby, A; Eng, P; Catalano, J G; Rosenqvist, J; Preocanin, T; Aytug, T; Zhang, D; Gan, Y; Braunschweig, B

    2018-01-01

    A wide range of isoelectric points (IEPs) has been reported in the literature for sapphire-c (α-alumina), also referred to as basal plane, (001) or (0001), single crystals. Interestingly, the available data suggest that the variation of IEPs is comparable to the range of IEPs encountered for particles, although single crystals should be much better defined in terms of surface structure. One explanation for the range of IEPs might be the obvious danger of contaminating the small surface areas of single crystal samples while exposing them to comparatively large solution reservoirs. Literature suggests that factors like origin of the sample, sample treatment or the method of investigation all have an influence on the surfaces and it is difficult to clearly separate the respective, individual effects. In the present study, we investigate cause-effect relationships to better understand the individual effects. The reference IEP of our samples is between 4 and 4.5. High temperature treatment tends to decrease the IEP of sapphire-c as does UV treatment. Increasing the initial miscut (i.e. the divergence from the expected orientation of the crystal) tends to increase the IEP as does plasma cleaning, which can be understood assuming that the surfaces have become less hydrophobic due to the presence of more and/or larger steps with increasing miscut or due to amorphisation of the surface caused by plasma cleaning. Pre-treatment at very high pH caused an increase in the IEP. Surface treatments that led to IEPs different from the stable value of reference samples typically resulted in surfaces that were strongly affected by subsequent exposure to water. The streaming potential data appear to relax to the reference sample behavior after a period of time of water exposure. Combination of the zeta-potential measurements with AFM investigations support the idea that atomically smooth surfaces exhibit lower IEPs, while rougher surfaces (roughness on the order of nanometers) result

  10. The influence of the interactions between anthropogenic activities and multiple ecological factors on land surface temperatures of urban forests

    Science.gov (United States)

    Ren, Y.

    2017-12-01

    Context Land surface temperatures (LSTs) spatio-temporal distribution pattern of urban forests are influenced by many ecological factors; the identification of interaction between these factors can improve simulations and predictions of spatial patterns of urban cold islands. This quantitative research requires an integrated method that combines multiple sources data with spatial statistical analysis. Objectives The purpose of this study was to clarify urban forest LST influence interaction between anthropogenic activities and multiple ecological factors using cluster analysis of hot and cold spots and Geogdetector model. We introduced the hypothesis that anthropogenic activity interacts with certain ecological factors, and their combination influences urban forests LST. We also assumed that spatio-temporal distributions of urban forest LST should be similar to those of ecological factors and can be represented quantitatively. Methods We used Jinjiang as a representative city in China as a case study. Population density was employed to represent anthropogenic activity. We built up a multi-source data (forest inventory, digital elevation models (DEM), population, and remote sensing imagery) on a unified urban scale to support urban forest LST influence interaction research. Through a combination of spatial statistical analysis results, multi-source spatial data, and Geogdetector model, the interaction mechanisms of urban forest LST were revealed. Results Although different ecological factors have different influences on forest LST, in two periods with different hot spots and cold spots, the patch area and dominant tree species were the main factors contributing to LST clustering in urban forests. The interaction between anthropogenic activity and multiple ecological factors increased LST in urban forest stands, linearly and nonlinearly. Strong interactions between elevation and dominant species were generally observed and were prevalent in either hot or cold spots

  11. High quality-factor quartz tuning fork glass probe used in tapping mode atomic force microscopy for surface profile measurement

    Science.gov (United States)

    Chen, Yuan-Liu; Xu, Yanhao; Shimizu, Yuki; Matsukuma, Hiraku; Gao, Wei

    2018-06-01

    This paper presents a high quality-factor (Q-factor) quartz tuning fork (QTF) with a glass probe attached, used in frequency modulation tapping mode atomic force microscopy (AFM) for the surface profile metrology of micro and nanostructures. Unlike conventionally used QTFs, which have tungsten or platinum probes for tapping mode AFM, and suffer from a low Q-factor influenced by the relatively large mass of the probe, the glass probe, which has a lower density, increases the Q-factor of the QTF probe unit allowing it to obtain better measurement sensitivity. In addition, the process of attaching the probe to the QTF with epoxy resin, which is necessary for tapping mode AFM, is also optimized to further improve the Q-factor of the QTF glass probe. The Q-factor of the optimized QTF glass probe unit is demonstrated to be very close to that of a bare QTF without a probe attached. To verify the effectiveness and the advantages of the optimized QTF glass probe unit, the probe unit is integrated into a home-built tapping mode AFM for conducting surface profile measurements of micro and nanostructures. A blazed grating with fine tool marks of 100 nm, a microprism sheet with a vertical amplitude of 25 µm and a Fresnel lens with a steep slope of 90 degrees are used as measurement specimens. From the measurement results, it is demonstrated that the optimized QTF glass probe unit can achieve higher sensitivity as well as better stability than conventional probes in the measurement of micro and nanostructures.

  12. Reversibly tethering growth factors to surfaces : guiding cell function at the cell-material interface

    NARCIS (Netherlands)

    Cabanas Danés, Jordi

    2013-01-01

    Development of novel methodologies for tethering growth factors (GFs) to materials is highly desired for the generation of biomaterials with improved tissue repair properties. Progress in the development of biomaterials that incorporate GFs and the in vivo performance of such biomaterials in tissue

  13. Persistence of DDT and parathion residues on a plant surface as influenced by weather factors

    NARCIS (Netherlands)

    Fahmy, H.S.M.

    1961-01-01

    The decay of DDT and parathion deposits under the influence of temperature, rain and ultraviolet radiation was described. Temperature and solar radiation were the main factors limiting the residual effect. High mean temperatures were more important than high maxima.

    DDT residues were more

  14. Pilot investigations of surface parts of three closed landfills and factors affecting them.

    Science.gov (United States)

    Saarela, Jouko

    2003-05-01

    Aftercare of closed sanitary landfills in a major environmental problem. Rehabilitation of the landfill with vegetation and reducing leachate production are two issues that must be dealt. For this reason, Finnish Environment Institute has conducted several projects on closed landfills. This research aims at determining the physical and chemical properties of the soils at three closed landfills in Helsinki, Finland. Research was conducted to understand the impact by studying the following properties: Chemical, nutrient metal, gamma and radon analysis of surface soils of three closed landfills in Helsinki area.

  15. Study of surface phenomena in biomaterials: The influence of physical factors

    Energy Technology Data Exchange (ETDEWEB)

    Sachelarie, Liliana, E-mail: lisachero@yahoo.com; Vasiliu, Mihaela Papusa; Ciobanu, Catalina

    2015-10-15

    This study's purpose is pointing out the phenomenon that occurs at time of interaction between the tissue with implant. The materials used are Ti and its alloys. The oral tissue must be compatible with the materials used in surgical implant to human body. The bio-materials surface behavior is influenced by physical characteristics. The methods we use show a number of bio-compatibility aspects. The success of an implant in a hard tissue depends not only on the initial attachment and the osteogenic cells consecutive proliferation, but also on their capacity to create a new bone.

  16. Factors influencing the cytotoxicity of zinc oxide nanoparticles: particle size and surface charge

    International Nuclear Information System (INIS)

    Baek, M; Kim, M K; Cho, H J; Lee, J A; Yu, J; Chung, H E; Choi, S J

    2011-01-01

    Zinc oxide (ZnO) nanoparticle is one of the most important materials in diverse applications, since it has UV light absorption, antimicrobial, catalytic, semi-conducting, and magnetic properties. However, there is little information about the toxicological effects of ZnO nanoparticles with respect to physicochemical properties. The aim of this study was, therefore, to evaluate the relationships between cytotoxicity and physicochemical properties of ZnO nanoparticle such as particle size and surface charge in human lung cells. Two different sizes of ZnO nanoparticles (20 and 70 nm) were prepared with positive (+) or negative (-) charge, and then, cytotoxicity of different ZnO nanoparticles was evaluated by measuring cell proliferation in short-term and long-term, membrane integrity, and generation of reactive oxygen species (ROS). The results demonstrated that smaller particles exhibited high cytotoxic effects compared to larger particles in terms of inhibition of cell proliferation, membrane damage, and ROS generation. In addition, positively charged ZnO showed greater ROS production than ZnO with negative charge. These findings suggest that the cytoxicity of ZnO nanoparticles are strongly affected by their particle size and surface charge, highlighting the role of the physicochemical properties of nanoparticles to understand and predict their potential adverse effects on human.

  17. Factors influencing the cytotoxicity of zinc oxide nanoparticles: particle size and surface charge

    Energy Technology Data Exchange (ETDEWEB)

    Baek, M; Kim, M K; Cho, H J; Lee, J A; Yu, J; Chung, H E; Choi, S J, E-mail: sjchoi@swu.ac.kr [Department of Food Science and Technology, Seoul Women' s University, 126 Gongneung 2-dong, Nowon-gu, Seoul 139-774 (Korea, Republic of)

    2011-07-06

    Zinc oxide (ZnO) nanoparticle is one of the most important materials in diverse applications, since it has UV light absorption, antimicrobial, catalytic, semi-conducting, and magnetic properties. However, there is little information about the toxicological effects of ZnO nanoparticles with respect to physicochemical properties. The aim of this study was, therefore, to evaluate the relationships between cytotoxicity and physicochemical properties of ZnO nanoparticle such as particle size and surface charge in human lung cells. Two different sizes of ZnO nanoparticles (20 and 70 nm) were prepared with positive (+) or negative (-) charge, and then, cytotoxicity of different ZnO nanoparticles was evaluated by measuring cell proliferation in short-term and long-term, membrane integrity, and generation of reactive oxygen species (ROS). The results demonstrated that smaller particles exhibited high cytotoxic effects compared to larger particles in terms of inhibition of cell proliferation, membrane damage, and ROS generation. In addition, positively charged ZnO showed greater ROS production than ZnO with negative charge. These findings suggest that the cytoxicity of ZnO nanoparticles are strongly affected by their particle size and surface charge, highlighting the role of the physicochemical properties of nanoparticles to understand and predict their potential adverse effects on human.

  18. Factors affecting the long-term response of surface waters to acidic deposition: state-of-the-science

    Energy Technology Data Exchange (ETDEWEB)

    Turner, R.S.; Johnson, D.W.; Elwood, J.N.; Van Winkle, W.; Clapp, R.B.; Jones, M.L.; Marmarek, D.R.; Thornton, K.W.; Gherinig, S.A.; Schnoor, J.L.

    1986-01-01

    Recent intensive study of the causes of surface water acidification has led to numerous hypothesized controlling mechanisms. Among these are the salt-effect reduction of alkalinity, the base cation buffering and sulfate adsorption capacities of soils, availability of weatherable minerals (weathering rates), depth of till, micropore flow, and type of forest cover. Correlative and predictive models have been developed to show the relationships (if any) between hypothesized controlling mechanisms and surface water acidity, and to suggest under what conditions additional surface water might become acid. This document (Part A) is a review of our current knowledge of factors and processes controlling soil and surface water acidification, as well as an assessment of the adequacy of that knowledge for making predictions of future acidification. Section 2 is a data extensive, conceptual overview of how watersheds function. Section 3 is a closer look at the theory and evidence for the key hypotheses. Section 4 is a review of existing methods of assessing system response to acidic deposition.

  19. Polyurethane Functional Coatings for Protection of Different Surfaces from Aggressive Environmental Factors

    Directory of Open Access Journals (Sweden)

    Savelyev, U.V., Markovska, L.A., Robota, L.P., Parkhomenko, N.I., and Savelyeva, O.O.

    2014-05-01

    Full Text Available New polyurethane compositions (PC as multifunctional protective materials that can serve as coatings or binders or impregnating materials have been created. PC have high adhesion values and the PC-based materials are waterproof and resistant to aggressive biotic (abiotic and technogenic factors (biocorrosion, UV radiation, chemical agents. Putting active compounds into the polymer macrochain prolongs the protection functions of the materials. This is their advantage to existing materials.

  20. Climatological Factors Affecting Electromagnetic Surface Ducting in the Aegean Sea Region

    Science.gov (United States)

    2012-03-01

    low precipitation, and northeasterly winds, all due to changes in large scale circulations and a northward shift in extratropical storm tracks. The...differences over the Aegean region, that are governed by large-scale climate factors. a. Winter During winter, the Aegean area is subject to extratropical ... extratropical cyclones from entering the Aegean region, while opposite shifts can 18 allow extratropical cyclones to more frequently enter the Aegean

  1. Effect of physicochemical factors on the microplasticity of the surface layer of molybdenum single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Savenko, V.I.; Kuchumova, V.M.; Kochanova, L.A.; Shchukin, E.D.

    1984-07-01

    The microplastic properties of the surface layer of molybdenum single crystals produced by electron-beam zone melting have been investigated experimentaly using ultramicrosclerometry and microindentation techniques. It is found that the 111 plane has the highest susceptibility to plastic damage, while the 100 plane is the hardest. An analysis of the stressed state of the material under an indenter shows that the dislocation density along the loading paths, which characterizes the microplasticity of the material, is largely determined by the crystallography of the lattice, i.e., by the arrangement and the number of effective slip systems in specimens of different orientations. The effect of a monolayer octadecylamine film on the microplastic behavior of molybdenum single crystals is discussed.

  2. Eukaryotic translation initiation factor 3 subunit e controls intracellular calcium homeostasis by regulation of cav1.2 surface expression.

    Directory of Open Access Journals (Sweden)

    Pawel Buda

    Full Text Available Inappropriate surface expression of voltage-gated Ca(2+channels (CaV in pancreatic ß-cells may contribute to the development of type 2 diabetes. First, failure to increase intracellular Ca(2+ concentrations at the sites of exocytosis impedes insulin release. Furthermore, excessive Ca(2+ influx may trigger cytotoxic effects. The regulation of surface expression of CaV channels in the pancreatic β-cells remains unknown. Here, we used real-time 3D confocal and TIRFM imaging, immunocytochemistry, cellular fractionation, immunoprecipitation and electrophysiology to study trafficking of L-type CaV1.2 channels upon β-cell stimulation. We found decreased surface expression of CaV1.2 and a corresponding reduction in L-type whole-cell Ca(2+ currents in insulin-secreting INS-1 832/13 cells upon protracted (15-30 min stimulation. This internalization occurs by clathrin-dependent endocytosis and could be prevented by microtubule or dynamin inhibitors. eIF3e (Eukaryotic translation initiation factor 3 subunit E is part of the protein translation initiation complex, but its effect on translation are modest and effects in ion channel trafficking have been suggested. The factor interacted with CaV1.2 and regulated CaV1.2 traffic bidirectionally. eIF3e silencing impaired CaV1.2 internalization, which resulted in an increased intracellular Ca(2+ load upon stimulation. These findings provide a mechanism for regulation of L-type CaV channel surface expression with consequences for β-cell calcium homeostasis, which will affect pancreatic β-cell function and insulin production.

  3. Round Robin Analyses on Stress Intensity Factors of Inner Surface Cracks in Welded Stainless Steel Pipes

    Directory of Open Access Journals (Sweden)

    Chang-Gi Han

    2016-12-01

    Full Text Available Austenitic stainless steels (ASSs are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  4. Emergence of entanglement with temperature and time in factorization-surface states

    Science.gov (United States)

    Chanda, Titas; Das, Tamoghna; Sadhukhan, Debasis; Pal, Amit Kumar; SenDe, Aditi; Sen, Ujjwal

    2018-01-01

    There exist zero-temperature states in quantum many-body systems that are fully factorized, thereby possessing vanishing entanglement, and hence being of no use as resource in quantum information processing tasks. Such states can become useful for quantum protocols when the temperature of the system is increased, and when the system is allowed to evolve under either the influence of an external environment, or a closed unitary evolution driven by its own Hamiltonian due to a sudden change in the system parameters. Using the one-dimensional anisotropic XY model in a uniform and an alternating transverse magnetic field, we show that entanglement of the thermal states, corresponding to the factorization points in the space of the system parameters, revives once or twice with increasing temperature. We also study the closed unitary evolution of the quantum spin chain driven out of equilibrium when the external magnetic fields are turned off, and show that considerable entanglement is generated during the dynamics, when the initial state has vanishing entanglement. Interestingly, we find that creation of entanglement for a pair of spins is possible when the system is made open to an external heat bath, interacting with the system through that spin-pair via a repetitive quantum interaction.

  5. Round robin analysis on stress intensity factor of inner surface cracks in welded stainless steel pipes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang Gi; Chang, Yoon Suk [Dept. of Nuclear Engineering, College of Engineering, Kyung Hee University, Yongin (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Sunchon (Korea, Republic of); Kim, Maan Won [Central Research Institute, Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)

    2016-12-15

    Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  6. Three-factor response surface optimization of nano-emulsion formation using a microfluidizer.

    Science.gov (United States)

    Sadeghpour Galooyak, Saeed; Dabir, Bahram

    2015-05-01

    Emulsification of sunflower oil in water by microfluidization was studied. Response surface methodology (RSM) and the central composite design (CCD) were applied to determine the effects of certain process parameters on performance of the apparatus for optimization of nano-emulsion fabrication. Influence of pressure, oil content and number of passes on the disruption of emulsions was studied. Quadratic multiple regression models were chosen for two available responses, namely Sauter mean diameter (SMD) and Polydispersity index (PdI). Analysis of variance (ANOVA) showed a high coefficient of determination (R(2)) value for both responses, confirming adjustment of the models with experimental data. The SMD and the PdI decreased as the pressure of emulsification increased from 408 to 762.3 bar for the oil content of 5 vol% and from 408 to 854.4 bar for the oil content of 13 vol%, and thereafter, increasing the pressure up to 952 bar led to increasing the both responses. The results implied that laminar elongational flow is the alternative disruption mechanism in addition to inertia in turbulence flow, especially at low treatment pressures. Both of responses improved with increase in number of passes from 2 to 4 cycles. The oil content depicted low effect on responses; however, interaction of this parameter with other regressors pointed remarkable impact. Also, the effect of pressure on Kolmogorov micro-scale was studied. The results implied that Kolmogorov equation did not take into account the over-processing and was applicable only for disruption of droplets in the inertial turbulent flow.

  7. Surface antigens and potential virulence factors from parasites detected by comparative genomics of perfect amino acid repeats

    Directory of Open Access Journals (Sweden)

    Adler Joël

    2007-12-01

    Full Text Available Abstract Background Many parasitic organisms, eukaryotes as well as bacteria, possess surface antigens with amino acid repeats. Making up the interface between host and pathogen such repetitive proteins may be virulence factors involved in immune evasion or cytoadherence. They find immunological applications in serodiagnostics and vaccine development. Here we use proteins which contain perfect repeats as a basis for comparative genomics between parasitic and free-living organisms. Results We have developed Reptile http://reptile.unibe.ch, a program for proteome-wide probabilistic description of perfect repeats in proteins. Parasite proteomes exhibited a large variance regarding the proportion of repeat-containing proteins. Interestingly, there was a good correlation between the percentage of highly repetitive proteins and mean protein length in parasite proteomes, but not at all in the proteomes of free-living eukaryotes. Reptile combined with programs for the prediction of transmembrane domains and GPI-anchoring resulted in an effective tool for in silico identification of potential surface antigens and virulence factors from parasites. Conclusion Systemic surveys for perfect amino acid repeats allowed basic comparisons between free-living and parasitic organisms that were directly applicable to predict proteins of serological and parasitological importance. An on-line tool is available at http://genomics.unibe.ch/dora.

  8. Fabrication and characterization of a novel microparticle with gyrus-patterned surface and growth factor delivery for cartilage tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Huang Sha [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Wang Yijuan [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi' an 710062 (China); Liang Tang [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Jin Fang [Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Liu Shouxin [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi' an 710062 (China); Jin Yan, E-mail: yanjin@fmmu.edu.cn [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China)

    2009-05-05

    Microparticles can serve as substrates for cell amplification and deliver the expanded cells to the site of the defect. It was hypothesized that a novel microparticle combined of sustained and localized delivery of proliferative growth factors and gyrus-patterned surface would influence the cell behaviours of adherence and expansion on the microparticle in the present study. To test the hypothesis, gelatin particles with diameter ranging from 280 to 350 {mu}m were fabricated and were modified by cryogenic freeze-drying treatment and basic fibroblast growth factor (bFGF) incorporation. The results of in vitro chondrocyte culture illustrated that cells could proliferate more obviously on the microparticles with bFGF addition, but no correlation between attachment rate and bFGF was observed. On the other hand, microparticles with gyrus-patterned surface demonstrated the highest cell attachment rate and higher rate of cell growth, in particular on bFGF combined ones. It seems to be a promising candidate as a chondrocyte microparticle and could be the potential application in cartilage tissue engineering.

  9. Fabrication and characterization of a novel microparticle with gyrus-patterned surface and growth factor delivery for cartilage tissue engineering

    International Nuclear Information System (INIS)

    Huang Sha; Wang Yijuan; Liang Tang; Jin Fang; Liu Shouxin; Jin Yan

    2009-01-01

    Microparticles can serve as substrates for cell amplification and deliver the expanded cells to the site of the defect. It was hypothesized that a novel microparticle combined of sustained and localized delivery of proliferative growth factors and gyrus-patterned surface would influence the cell behaviours of adherence and expansion on the microparticle in the present study. To test the hypothesis, gelatin particles with diameter ranging from 280 to 350 μm were fabricated and were modified by cryogenic freeze-drying treatment and basic fibroblast growth factor (bFGF) incorporation. The results of in vitro chondrocyte culture illustrated that cells could proliferate more obviously on the microparticles with bFGF addition, but no correlation between attachment rate and bFGF was observed. On the other hand, microparticles with gyrus-patterned surface demonstrated the highest cell attachment rate and higher rate of cell growth, in particular on bFGF combined ones. It seems to be a promising candidate as a chondrocyte microparticle and could be the potential application in cartilage tissue engineering.

  10. Facile modification of gelatin-based microcarriers with multiporous surface and proliferative growth factors delivery to enhance cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Huang Sha [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Wang Yijuan [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi' an 710062 (China); Deng, Tianzheng [Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Department of Oral and Maxillofacial Surgery, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Jin Fang [Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi' an, 710032 (China); Liu Shouxin [Key Laboratory for Macromolecular Science of Shaanxi Province, Shaanxi Normal University, Xi' an 710062 (China); Zhang Yongjie [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Feng Feng [Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China); Department of Dermatology, Tangdu Hospital, Fourth Military Medical University, Xi' an 710038 (China); Jin Yan [Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi' an 710032 (China); Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi' an 710032 (China)], E-mail: yanjin@fmmu.edu.cn

    2008-07-28

    The design of microcarriers plays an important role in the success of cell expansion. The present article provides a facile approach to modify the gelatin-based particles and investigates the feasibility of their acting as microcarriers for cell attachment and growth. Gelatin particles (150-320 {mu}m) were modified by cryogenic treatment and lyophilization to develop the surface with the features of multiporous morphology and were incorporated with proliferative growth factors (bFGF) by adsorption during the post-preparation, which enables them to serve as microcarriers for cells amplification, together with the advantages of larger cell-surface contact area and capability of promoting cell propagation. The microstructure and release assay of the modified microcarriers demonstrated that the pores on surface were uniform and bFGF was released in a controlled manner. Through in vitro fibroblast culture, these features resulted in a prominent increase in the cell attachment rate and cell growth rate relative to the conditions without modification. Although the scanning electron microscopy and optical microscopy analysis results indicated that cells attached, spread, and proliferated on all the microcarriers, cell growth clearly showed a significant correlation with the multiporous structure of microcarriers, in particular on bFGF combined ones. These results validate our previous assumption that the facile modification could improve cell growth on the gelatin-based microcarriers obviously and the novel microcarriers may be a promising candidate in tissue engineering.

  11. Stress intensity factors for deep cracks emanating from the corner formed by a hole intersecting a plate surface

    Science.gov (United States)

    Mcgowan, J. J.; Smith, C. W.

    1976-01-01

    The stress intensity factors (SIFs) at the end points of flaws emanating from the corner formed by the intersection of a plate with a hole were determined using stress freezing photoelasticity and a numerical technique known as the Taylor series correction method to extract the SIF values from the photoelastic data. The geometries studied were crack depth to thickness ratios of about 0.2, 0.5, and 0.75; crack depth to crack length ratios of about 1.0 to 2.0; and crack length to hole radius ratios of about 0.5 to 2.0. The SIFs were determined at the intersection of the flaw border with the plate surface (KS) and with the edge of the hole (KH). It is shown that extension of a crack emanating from a corner of intersection of a hole with a plate under monotonically increasing load is not self-similar and that as the flaw depth increases, KH decreases and KS increases. Existing theories and design criteria significantly overestimate the SIF at both the hole and the surface except for shallow flaws at the hole and deep flaws at the surface.

  12. Facile modification of gelatin-based microcarriers with multiporous surface and proliferative growth factors delivery to enhance cell growth

    International Nuclear Information System (INIS)

    Huang Sha; Wang Yijuan; Deng, Tianzheng; Jin Fang; Liu Shouxin; Zhang Yongjie; Feng Feng; Jin Yan

    2008-01-01

    The design of microcarriers plays an important role in the success of cell expansion. The present article provides a facile approach to modify the gelatin-based particles and investigates the feasibility of their acting as microcarriers for cell attachment and growth. Gelatin particles (150-320 μm) were modified by cryogenic treatment and lyophilization to develop the surface with the features of multiporous morphology and were incorporated with proliferative growth factors (bFGF) by adsorption during the post-preparation, which enables them to serve as microcarriers for cells amplification, together with the advantages of larger cell-surface contact area and capability of promoting cell propagation. The microstructure and release assay of the modified microcarriers demonstrated that the pores on surface were uniform and bFGF was released in a controlled manner. Through in vitro fibroblast culture, these features resulted in a prominent increase in the cell attachment rate and cell growth rate relative to the conditions without modification. Although the scanning electron microscopy and optical microscopy analysis results indicated that cells attached, spread, and proliferated on all the microcarriers, cell growth clearly showed a significant correlation with the multiporous structure of microcarriers, in particular on bFGF combined ones. These results validate our previous assumption that the facile modification could improve cell growth on the gelatin-based microcarriers obviously and the novel microcarriers may be a promising candidate in tissue engineering

  13. Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico.

    Science.gov (United States)

    Liu, Jiqing; Bacosa, Hernando P; Liu, Zhanfei

    2016-01-01

    Understanding bacterial community dynamics as a result of an oil spill is important for predicting the fate of oil released to the environment and developing bioremediation strategies in the Gulf of Mexico. In this study, we aimed to elucidate the roles of temperature, water chemistry (nutrients), and initial bacterial community in selecting oil degraders through a series of incubation experiments. Surface (2 m) and bottom (1537 m) waters, collected near the Deepwater Horizon site, were amended with 200 ppm light Louisiana sweet crude oil and bacterial inoculums from surface or bottom water, and incubated at 4 or 24°C for 50 days. Bacterial community and residual oil were analyzed by pyrosequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that temperature played a key role in selecting oil-degrading bacteria. Incubation at 4°C favored the development of Cycloclasticus, Pseudoalteromonas , Sulfitobacter , and Reinekea , while 24°C incubations enhanced Oleibacter, Thalassobius, Phaeobacter, and Roseobacter. Water chemistry and the initial community also had potential roles in the development of hydrocarbon-degrading bacterial communities. Pseudoalteromonas , Oleibacter , and Winogradskyella developed well in the nutrient-enriched bottom water, while Reinekea and Thalassobius were favored by low-nutrient surface water. We revealed that the combination of 4°C, crude oil and bottom inoculum was a key factor for the growth of Cycloclasticus , while the combination of surface inoculum and bottom water chemistry was important for the growth of Pseudoalteromonas . Moreover, regardless of the source of inoculum, bottom water at 24°C was a favorable condition for Oleibacter. Redundancy analysis further showed that temperature and initial community explained 57 and 19% of the variation observed, while oil and water chemistry contributed 14 and 10%, respectively. Overall, this study revealed the relative roles of temperature, water

  14. [Prevalence of hepatitis B surface antigen and its associated factors in Senegalese military personnel sent on mission to Darfur].

    Science.gov (United States)

    Diop, Moustapha; Diouf, Assane; Seck, Said Malaobé; Lo, Gora; Ka, Daye; Massaly, Aminata; Dieye, Alassane; Fall, Ndeye Maguette; Cisse-Diallo, Viviane Marie Pierre; Diallo-Mbaye, Khardiata; Lakhe, Ndèye Aissatou; Fortes-Déguénonvo, Louise; Ndour, Cheikh Tidiane; Soumaré, Maserigne; Seydi, Moussa

    2017-01-01

    In Senegal, 85% of the adult population have been exposed to the hepatitis B virus and about 11% of them are chronic surface antigen (HBsAg) carriers. This infection is poorly documented among Senegalese Armed Forces. The aim of this study was to assess the prevalence of HBsAg in Senegalese military personnel on mission to Darfur (Sudan) and to identify its associated factors. We conducted a cross-sectional study among Senegalese military personnel stationed in Darfur from 1 July 2014 to 31 July 2014. HBsAg test was performed on serum of participants using immunochromatographic method. The search for associated factors was carried out using multivariate logistic regression. Our study included 169 male military personnel. The average age was 36.6 ± 9.5 years. A history of familial chronic liver disease, blood exposure and sexual exposure were found in 12.4%, 24.9% and 45.6% of the study population respectively. HBsAg was found in 24 participants [14.2% (CI 95% = 8.9-19.5)]. After adjusting for potential confounding factors, age (OR = 0.9 CI 95% = 0.9-1.0), university level (OR = 9.5 CI 95% = 1.3 - 67 , 1>) and sexual exposure (OR = 3.3 <; CI 95% = 1.0 - 10.3) were independently associated with hepatitis B. Our study shows high prevalence of HBsAg and underlines the need for further evaluation of hepatitis B in this population.

  15. Key factors influencing the stability of silane solution during long-term surface treatment on carbon steel

    International Nuclear Information System (INIS)

    Xian, Xiaochao; Chen, Minglu; Li, Lixin; Lin, Zhen; Xiang, Jun; Zhao, Shuo

    2013-01-01

    Highlights: •The corrosion-resistance time of silane films decreases with increasing cycle numbers. •The morphology of silane films prepared from aged solution is inhomogeneous. •Introduction of contamination ions is one reason for the poor property of aged solution. •Consumption of silane is the other reason for the poor property of aged solution. •Fe 3+ accumulated is the key factor influencing the property of silane solution. -- Abstract: The mixtures of bis-[trimethoxysilylpropyl]amine and vinyltriacetoxysilane were used for surface treatment of carbon steel, aiming to investigate the factors influencing the stability of silane solution during long-term experiment from two aspects. One is the concentrations of contamination ions, and the other is mass of silane consumed per cycle which is calculated according to concentration of Si measured by silicon molybdenum blue photometry. The results indicate that the accumulation of contamination ions, especially Fe 3+ , is the main factor leading to the condensation between the Si–OH groups in silane solution, which is responsible for the downward stability of silane solution

  16. The surface orientation dependence of the pre-exponential factors extracted from the segregation profiles of a Cu(111/110) bi-crystal

    CSIR Research Space (South Africa)

    Jafta, CJ

    2011-07-01

    Full Text Available Previous experimental investigations have only shown, without explanation, that the pre-exponential factor (D0), in the diffusion coefficient of Sb segregating in Cu, is dependent on the surface orientation of a crystal. In this study, the surface...

  17. Analytical Electron Diffraction from Iii-V and II-Vi Semiconductors

    Science.gov (United States)

    Spellward, Paul

    Available from UMI in association with The British Library. This thesis describes the development and evaluation of a number of new TEM-based techniques for the measurement of composition in ternary III-V and II-VI semiconductors. New methods of polarity determination in binary and ternary compounds are also presented. The theory of high energy electron diffraction is outlined, with particular emphasis on zone axis diffraction from well-defined strings. An account of TEM microstructural studies of Cd_{rm x}Hg _{rm 1-x}Te and CdTe epitaxial layers, which provided the impetus for developing the diffraction-based analytical techniques, is given. The wide range of TEM-based compositional determination techniques is described. The use of HOLZ deficiency lines to infer composition from a lattice parameter measurement is evaluated. In the case of Cd_{ rm x}Hg_{rm 1-x}Te, it is found to be inferior to other techniques developed. Studies of dynamical aspects of HOLZ diffraction can yield information about the dispersion surface from which a measure of composition may be obtained. This technique is evaluated for Al_{rm x}Ga_{rm 1-x} As, in which it is found to be of some use, and for Cd_{rm x}Hg _{rm 1-x}Te, in which the large Debye-Waller factor associated with mercury in discovered to render the method of little value. A number of critical voltages may be measured in medium voltage TEMs. The (111) zone axis critical voltage of Cd_{rm x}Hg _{rm 1-x}Te is found to vary significantly with x and forms the basis of an accurate technique for composition measurement in that ternary compound. Other critical voltage phenomena are investigated. In Al _{rm x}Ga_ {rm 1-x}As and other light ternaries, a non-systematic critical voltage is found to vary with x, providing a good indicator of composition. Critical voltage measurements may be made by conventional CBED or by various other techniques, which may also simultaneously yield information on the spatial variation of composition. The

  18. An acceleration of the characteristics by a space-angle two-level method using surface discontinuity factors

    Energy Technology Data Exchange (ETDEWEB)

    Grassi, G. [Commissariat a l' Energie Atomique, CEA de Saclay, DM2S/SERMA/LENR, 91191, Gif-sur-Yvette (France)

    2006-07-01

    We present a non-linear space-angle two-level acceleration scheme for the method of the characteristics (MOC). To the fine level on which the MOC transport calculation is performed, we associate a more coarsely discretized phase space in which a low-order problem is solved as an acceleration step. Cross sections on the coarse level are obtained by a flux-volume homogenisation technique, which entails the non-linearity of the acceleration. Discontinuity factors per surface are introduced as additional degrees of freedom on the coarse level in order to ensure the equivalence of the heterogeneous and the homogenised problem. After each fine transport iteration, a low-order transport problem is iteratively solved on the homogenised grid. The solution of this problem is then used to correct the angular moments of the flux resulting from the previous free transport sweep. Numerical tests for a given benchmark have been performed. Results are discussed. (authors)

  19. An acceleration of the characteristics by a space-angle two-level method using surface discontinuity factors

    International Nuclear Information System (INIS)

    Grassi, G.

    2006-01-01

    We present a non-linear space-angle two-level acceleration scheme for the method of the characteristics (MOC). To the fine level on which the MOC transport calculation is performed, we associate a more coarsely discretized phase space in which a low-order problem is solved as an acceleration step. Cross sections on the coarse level are obtained by a flux-volume homogenisation technique, which entails the non-linearity of the acceleration. Discontinuity factors per surface are introduced as additional degrees of freedom on the coarse level in order to ensure the equivalence of the heterogeneous and the homogenised problem. After each fine transport iteration, a low-order transport problem is iteratively solved on the homogenised grid. The solution of this problem is then used to correct the angular moments of the flux resulting from the previous free transport sweep. Numerical tests for a given benchmark have been performed. Results are discussed. (authors)

  20. Seroprevalence of Hepatitis B Surface Antigen and Occupational Risk Factors Among Health Care Workers in Ekiti State, Nigeria

    Science.gov (United States)

    Alese, Oluwole Ojo; Ohunakin, Afolabi; Oluyide, Peter Olumuyiwa

    2016-01-01

    Introduction Hepatitis B virus (HBV) infection is contracted from blood and other body fluid making healthcare workers (HCW) prone to the infection especially in the developing world. Though it is a vaccine preventable disease, the level of awareness and universal precaution among HCW is low in sub-Saharan African and Asia. Aim The study was aimed at determining the seroprevalence of hepatitis B surface antigen and occupational risk factors among health care workers at Ekiti State University Teaching Hospital, Ado Ekiti. Materials and Methods One hundred and eighty-seven (187) blood samples were collected from volunteer subjects who comprised of medical doctors, nurses, health attendants, and porters who are in regular contact with blood, body fluids and patients after informed consent. Well detailed and structured questionnaires were used to obtain demographic and other relevant data from the subjects. Blood samples were tested by Enzyme Linked Immunosorbent assay (ELISA) for hepatitis B surface antigen. Results Out of the 187 HCWs there were 91 males (48.7%) and 96 (51.3%) females. Only 2 participants tested positive to hepatitis B surface antigen with a prevalence of 1.1%. Also, only 30 (16.0%) of the participants had been fully vaccinated against the infection while the remaining 157(84.0%) had no adult vaccination. Conclusion It is obvious that the awareness of the infection is low among the HCWs studied thus the need to incorporate screening for HbsAg and vaccination against HBV into the periodic/pre-employment health intervention programmes by employers to help in the protection of HCWs and control the spread of the virus. PMID:27042489

  1. Seroprevalence of Hepatitis B Surface Antigen and Occupational Risk Factors Among Health Care Workers in Ekiti State, Nigeria.

    Science.gov (United States)

    Alese, Oluwole Ojo; Alese, Margaret Olutayo; Ohunakin, Afolabi; Oluyide, Peter Olumuyiwa

    2016-02-01

    Hepatitis B virus (HBV) infection is contracted from blood and other body fluid making healthcare workers (HCW) prone to the infection especially in the developing world. Though it is a vaccine preventable disease, the level of awareness and universal precaution among HCW is low in sub-Saharan African and Asia. The study was aimed at determining the seroprevalence of hepatitis B surface antigen and occupational risk factors among health care workers at Ekiti State University Teaching Hospital, Ado Ekiti. One hundred and eighty-seven (187) blood samples were collected from volunteer subjects who comprised of medical doctors, nurses, health attendants, and porters who are in regular contact with blood, body fluids and patients after informed consent. Well detailed and structured questionnaires were used to obtain demographic and other relevant data from the subjects. Blood samples were tested by Enzyme Linked Immunosorbent assay (ELISA) for hepatitis B surface antigen. Out of the 187 HCWs there were 91 males (48.7%) and 96 (51.3%) females. Only 2 participants tested positive to hepatitis B surface antigen with a prevalence of 1.1%. Also, only 30 (16.0%) of the participants had been fully vaccinated against the infection while the remaining 157(84.0%) had no adult vaccination. It is obvious that the awareness of the infection is low among the HCWs studied thus the need to incorporate screening for HbsAg and vaccination against HBV into the periodic/pre-employment health intervention programmes by employers to help in the protection of HCWs and control the spread of the virus.

  2. Plasma rich in growth factors eye drops to treat secondary ocular surface disorders in patients with glaucoma.

    Science.gov (United States)

    Sánchez-Avila, Ronald M; Merayo-Lloves, Jesus; Fernández, Maria Laura; Rodríguez-Gutiérrez, Luis Alberto; Rodríguez-Calvo, Pedro Pablo; Fernández-Vega Cueto, Andres; Muruzabal, Francisco; Orive, Gorka; Anitua, Eduardo

    2018-01-01

    To evaluate the efficacy and safety of plasma rich in growth factors (PRGF) eye drops in patients with glaucoma with secondary ocular surface disorders (OSDs) due to surgeries and topical hypotensive drugs use. A retrospective case-series study design was used including six patients (eight eyes) diagnosed with glaucoma who received surgical (nonpenetrating deep sclerectomy and/or trabeculectomy) and medical treatments (hypotensive eye drops) to control intraocular pressure (IOP) and who developed secondary OSDs, unresponsive to conventional treatments. Patients were treated with PRGF eye drops (four times a day). Outcome measures were ocular surface disease index (OSDI), best-corrected visual acuity (BCVA, in logarithm of the minimum angle of resolution), visual analog scale (VAS), frequency and severity of symptoms, and IOP. The safety of the treatment was also evaluated. Six patients (seven eyes with open-angle glaucoma and one eye with uveitic glaucoma) treated with PRGF eye drops were evaluated. Mean age was 71 years (SD=7.2, range 58-79 years). Five were female and one was male. The mean treatment time was 21.8 weeks (SD=9.0, range 12-36 weeks). The mean time to reach closure of the corneal ulcer was 14.5 (SD=5.5) weeks. A statistical significant reduction in OSDI scale (50.6%), VAS frequency (53.1%), VAS severity (42.0%), and a 41.8% improvement in BCVA were observed ( p PRGF eye drops until the end of therapy; the remaining patients did not report any AEs during the follow-up period. In patients with glaucoma and secondary OSDs refractive to conventional treatments, the treatment with PRGF eye drops could be considered a possible therapeutic option, because it demonstrates an improvement in the signs and symptoms of the ocular surface, as well as a better control of the IOP. This is an initial research work that can open doors for future research to confirm these findings.

  3. The sea surface currents as a potential factor in the estimation and monitoring of wave energy potential

    Science.gov (United States)

    Zodiatis, George; Galanis, George; Nikolaidis, Andreas; Stylianoy, Stavros; Liakatas, Aristotelis

    2015-04-01

    The use of wave energy as an alternative renewable is receiving attention the last years under the shadow of the economic crisis in Europe and in the light of the promising corresponding potential especially for countries with extended coastline. Monitoring and studying the corresponding resources is further supported by a number of critical advantages of wave energy compared to other renewable forms, like the reduced variability and the easier adaptation to the general grid, especially when is jointly approached with wind power. Within the framework, a number of countries worldwide have launched research and development projects and a significant number of corresponding studies have been presented the last decades. However, in most of them the impact of wave-sea surface currents interaction on the wave energy potential has not been taken into account neglecting in this way a factor of potential importance. The present work aims at filling this gap for a sea area with increased scientific and economic interest, the Eastern Mediterranean Sea. Based on a combination of high resolution numerical modeling approach with advanced statistical tools, a detailed analysis is proposed for the quantification of the impact of sea surface currents, which produced from downscaling the MyOcean-FO regional data, to wave energy potential. The results although spatially sensitive, as expected, prove beyond any doubt that the wave- sea surface currents interaction should be taken into account for similar resource analysis and site selection approaches since the percentage of impact to the available wave power may reach or even exceed 20% at selected areas.

  4. Comparison of phosphorus fraction distribution and influencing factors of suspended and surface sediments in the Tiaoxi watershed, China.

    Science.gov (United States)

    Ye, Hongmeng; Yuan, Xuyin; Han, Lei; Yin, Heng; Jin, Jing

    2017-05-01

    Suspended and surface sediments from the Tiaoxi watershed, fed by the Xitiaoxi and Dongtiaoxi rivers, were analyzed for total phosphorus (TP) and the inorganic P fractions of loosely adsorbed P that were extractable with NH 4 Cl (NH 4 Cl-P), reductant P (BD-P), metal oxide-bound P extractable with NaOH (NaOH-P), and calcium-bound, HCl-extractable P (HCl-P), while other physicochemical compositions were also determined. The spatial variations of P fractions in these sediments were investigated, and the major factors influencing the various fractions were explored by multivariate statistics. Compared to surface sediments, suspended sediments contained considerably higher concentrations of total nitrogen, TP, organic matter, Al, Fe, Mn and biologically available P (BAP, given as NH 4 Cl-P, BD-P and NaOH-P combined) and lower concentrations of Si, Ca and HCl-P in the studied catchments. Dongtiaoxi sediments had higher TP, inorganic phosphorus and HCl-P concentrations and a lower BAP content compared with Xitiaoxi sediments, trends that were associated with local geological backgrounds, landscapes and anthropogenic characteristics. The results of principal component analysis showed different effects of sediment properties on P fraction distributions for Xitiaoxi and Dongtiaoxi sediments. The sediment components and structure exert a strong influence on BAP in Xitiaoxi sediments, in contrast to Dongtiaoxi sediments, where P fractions are mainly affected by urbanization and other anthropogenic activities such as shipping.

  5. Characterization of a Staphylococcus aureus surface virulence factor that promotes resistance to oxidative killing and infectious endocarditis.

    Science.gov (United States)

    Malachowa, Natalia; Kohler, Petra L; Schlievert, Patrick M; Chuang, Olivia N; Dunny, Gary M; Kobayashi, Scott D; Miedzobrodzki, Jacek; Bohach, Gregory A; Seo, Keun Seok

    2011-01-01

    Staphylococcus aureus is a prominent human pathogen and a leading cause of community- and hospital-acquired bacterial infections worldwide. Herein, we describe the identification and characterization of the S. aureus 67.6-kDa hypothetical protein, named for the surface factor promoting resistance to oxidative killing (SOK) in this study. Sequence analysis showed that the SOK gene is conserved in all sequenced S. aureus strains and homologous to the myosin cross-reactive antigen of Streptococcus pyogenes. Immunoblotting and immunofluorescence analysis showed that SOK was copurified with membrane fractions and was exposed on the surface of S. aureus Newman and RN4220. Comparative analysis of wild-type S. aureus and an isogenic deletion strain indicated that SOK contributes to both resistance to killing by human neutrophils and to oxidative stress. In addition, the S. aureus sok deletion strain showed dramatically reduced aortic valve vegetation and bacterial cell number in a rabbit endocarditis model. These results, plus the suspected role of the streptococcal homologue in certain diseases such as acute rheumatic fever, suggest that SOK plays an important role in cardiovascular and other staphylococcal infections.

  6. The influence of wall orientation and exterior surface solar absorptivity on time lag and decrement factor in the Greek region

    Energy Technology Data Exchange (ETDEWEB)

    Kontoleon, K.J.; Eumorfopoulou, E.A. [Department of Civil Engineering, Laboratory of Building Construction and Physics, Aristotle University of Thessaloniki (A.U.Th.), Gr-541 24 Thessaloniki (Greece)

    2008-07-15

    The aim of this study is to determine how time lag and decrement factor are affected by wall orientation and exterior surface solar absorptivity, for specific climatic conditions. Their influence forms a non-sinusoidal periodical forcing function that simulates suitably the outdoor temperature fluctuations. This novel approach, allows the predictability of building's thermal response in an efficient way. The investigation is carried out for various insulated opaque wall formations comprising typical material elements, during the summer period in the mild Greek region. This study that allows proper building planning procedures, at the very early stages of the envelope design, presents great importance. The analysed configurations are assumed to have an orientation that corresponds to each compass point. In addition, the solar absorptivity of surface coatings is assumed to be varying from 0 to 1. The transient thermal analysis is obtained via a thermal circuit that models accurately the fundamental heat transfer mechanisms on both boundaries and through the multi-layered wall configurations. Moreover, the mathematical formulation and solution of this lumped model is achieved in discrete time steps by adopting the non-linear nodal method. The simulation results are focused on the single and combined effects of orientation and solar absorptivity on the dynamic thermal characteristics of various wall configurations. (author)

  7. Atomic and molecular adsorption on transition-metal carbide (111) surfaces from density-functional theory: a trend study of surface electronic factors

    DEFF Research Database (Denmark)

    Vojvodic, Aleksandra; Ruberto, C.; Lundqvist, Bengt

    2010-01-01

    ) surfaces. The spatial extent and the dangling bond nature of these SRs are supported by real-space analyses of the calculated Kohn-Sham wavefunctions. Then, atomic and molecular adsorption energies, geometries, and charge transfers are presented. An analysis of the adsorbate-induced changes in surface DOSs...

  8. Inflammatory Cytokine Tumor Necrosis Factor α Confers Precancerous Phenotype in an Organoid Model of Normal Human Ovarian Surface Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Joseph Kwong

    2009-06-01

    Full Text Available In this study, we established an in vitro organoid model of normal human ovarian surface epithelial (HOSE cells. The spheroids of these normal HOSE cells resembled epithelial inclusion cysts in human ovarian cortex, which are the cells of origin of ovarian epithelial tumor. Because there are strong correlations between chronic inflammation and the incidence of ovarian cancer, we used the organoid model to test whether protumor inflammatory cytokine tumor necrosis factor α would induce malignant phenotype in normal HOSE cells. Prolonged treatment of tumor necrosis factor α induced phenotypic changes of the HOSE spheroids, which exhibited the characteristics of precancerous lesions of ovarian epithelial tumors, including reinitiation of cell proliferation, structural disorganization, epithelial stratification, loss of epithelial polarity, degradation of basement membrane, cell invasion, and overexpression of ovarian cancer markers. The result of this study provides not only an evidence supporting the link between chronic inflammation and ovarian cancer formation but also a relevant and novel in vitro model for studying of early events of ovarian cancer.

  9. Studying the Impacts of Environmental Factors and Agricultural Management on Methane Emissions from Rice Paddies Using a Land Surface Model

    Science.gov (United States)

    Lin, T. S.; Gahlot, S.; Shu, S.; Jain, A. K.; Kheshgi, H. S.

    2017-12-01

    Continued growth in population is projected to drive increased future demand for rice and the methane emissions associated with its production. However, observational studies of methane emissions from rice have reported seemingly conflicting results and do not all support this projection. In this study we couple an ecophysiological process-based rice paddy module and a methane emission module with a land surface model, Integrated Science Assessment Model (ISAM), to study the impacts of various environmental factors and agricultural management practices on rice production and methane emissions from rice fields. This coupled modeling framework accounts for dynamic rice growth processes with adaptation of photosynthesis, rice-specific phenology, biomass accumulation, leaf area development and structures responses to water, temperature, light and nutrient stresses. The coupled model is calibrated and validated with observations from various rice cultivation fields. We find that the differing results of observational studies can be caused by the interactions of environmental factors, including climate, atmospheric CO2 concentration, and N deposition, and agricultural management practices, such as irrigation and N fertilizer applications, with rice production at spatial and temporal scales.

  10. Features, events, processes, and safety factor analysis applied to a near-surface low-level radioactive waste disposal facility

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, M.E.; Dolinar, G.M.; Lange, B.A. [Atomic Energy of Canada Limited, Ontario (Canada)] [and others

    1995-12-31

    An analysis of features, events, processes (FEPs) and other safety factors was applied to AECL`s proposed IRUS (Intrusion Resistant Underground Structure) near-surface LLRW disposal facility. The FEP analysis process which had been developed for and applied to high-level and transuranic disposal concepts was adapted for application to a low-level facility for which significant efforts in developing a safety case had already been made. The starting point for this process was a series of meetings of the project team to identify and briefly describe FEPs or safety factors which they thought should be considered. At this early stage participants were specifically asked not to screen ideas. This initial list was supplemented by selecting FEPs documented in other programs and comments received from an initial regulatory review. The entire list was then sorted by topic and common issues were grouped, and issues were classified in three priority categories and assigned to individuals for resolution. In this paper, the issue identification and resolution process will be described, from the initial description of an issue to its resolution and inclusion in the various levels of the safety case documentation.

  11. Effects of Inner Surface Roughness and Asymmetric Pipe Flow on Accuracy of Profile Factor for Ultrasonic Flow Meter

    International Nuclear Information System (INIS)

    Michitsugu Mori; Kenichi Tezuka; Yasushi Takeda

    2006-01-01

    Flow profile factors (PFs), which adjust measurements to real flow rates, also strongly depend on flow profiles. To determine profile factors for actual power plants, manufactures of flowmeters usually conduct factory calibration tests under ambient flow conditions. Indeed, flow measurements with high accuracy for reactor feedwater require them to conduct calibration tests under real conditions, such as liquid conditions and piping layouts. On the contrary, as nuclear power plants are highly aging, readings of flowmeters for reactor feedwater systems drift due to the changes of flow profiles. The causes of those deviations are affected by the change of wall roughness of inner surface of pipings. We have conducted experiments to quantify the effects of flow patterns on the PFs due to pipe roughness and asymmetric flow, and the results of our experiments have shown the effects of elbows and pipe inner roughness, which strongly affect to the creation of the flow patterns. Those changes of flow patterns lead to large errors in measurements with transit time (time-of-flight: TOF) ultrasonic flow meters. In those experiments, changes of pipe roughness result in the changes of PFs with certain errors. Therefore, we must take into account those effects in order to measure the flow rates of feedwater with better accuracy in actual power plants. (authors)

  12. Per a 10 protease activity modulates CD40 expression on dendritic cell surface by nuclear factor-kappaB pathway.

    Science.gov (United States)

    Goel, C; Kalra, N; Dwarakanath, B S; Gaur, S N; Arora, N

    2015-05-01

    Serine protease activity of Per a 10 from Periplaneta americana modulates dendritic cell (DC) functions by a mechanism(s) that remains unclear. In the present study, Per a 10 protease activity on CD40 expression and downstream signalling was evaluated in DCs. Monocyte-derived DCs from cockroach-allergic patients were treated with proteolytically active/heat-inactivated Per a 10. Stimulation with active Per a 10 demonstrated low CD40 expression on DCs surface (P Per a 10, suggesting cleavage of CD40. Per a 10 activity reduced the interleukin (IL)-12 and interferon (IFN)-γ secretion by DCs (P Per a 10, indicating that low CD40 expression is associated with low levels of IL-12 secretion. Active Per a 10 stimulation caused low nuclear factor-kappa B (NF-κB) activation in DCs compared to heat-inactivated Per a 10. Inhibition of the NF-κB pathway suppressed the CD40 expression and IL-12 secretion by DCs, further indicating that NF-κB is required for CD40 up-regulation. CD40 expression activated the tumour necrosis factor (TNF) receptor-associated factor 6 (TRAF6), thereby suggesting its involvement in NF-κB activation. Protease activity of Per a 10 induced p38 mitogen-activated protein kinase (MAPK) activation that showed no significant effect on CD40 expression by DCs. However, inhibiting p38 MAPK or NF-κB suppressed the secretion of IL-12, IFN-γ, IL-6 and TNF-α by DCs. Such DCs further reduced the secretion of IL-4, IL-6, IL-12 and TNF-α by CD4(+) T cells. In conclusion, protease activity of Per a 10 reduces CD40 expression on DCs. CD40 down-regulation leads to low NF-κB levels, thereby modulating DC-mediated immune responses. © 2014 British Society for Immunology.

  13. Analysis of factors controlling soil phosphorus loss with surface runoff in Huihe National Nature Reserve by principal component and path analysis methods.

    Science.gov (United States)

    He, Jing; Su, Derong; Lv, Shihai; Diao, Zhaoyan; Bu, He; Wo, Qiang

    2018-01-01

    Phosphorus (P) loss with surface runoff accounts for the P input to and acceleration of eutrophication of the freshwater. Many studies have focused on factors affecting P loss with surface runoff from soils, but rarely on the relationship among these factors. In the present study, rainfall simulation on P loss with surface runoff was conducted in Huihe National Nature Reserve, in Hulunbeier grassland, China, and the relationships between P loss with surface runoff, soil properties, and rainfall conditions were examined. Principal component analysis and path analysis were used to analyze the direct and indirect effects on P loss with surface runoff. The results showed that P loss with surface runoff was closely correlated with soil electrical conductivity, soil pH, soil Olsen P, soil total nitrogen (TN), soil total phosphorus (TP), and soil organic carbon (SOC). The main driving factors which influenced P loss with surface runoff were soil TN, soil pH, soil Olsen P, and soil water content. Path analysis and determination coefficient analysis indicated that the standard multiple regression equation for P loss with surface runoff and each main factor was Y = 7.429 - 0.439 soil TN - 6.834 soil pH + 1.721 soil Olsen-P + 0.183 soil water content (r = 0.487, p runoff. The effect of physical and chemical properties of undisturbed soils on P loss with surface runoff was discussed, and the soil water content and soil Olsen P were strongly positive influences on the P loss with surface runoff.

  14. Tyres and road surfaces : experimental multifactor investigation of the factors affecting the brake and side way forces between car tyres and wet road surfaces : summary, conclusions and recommendations from the study by Sub-Committee I of the Working Group on "Tyres, Road Surfaces and Skidding Accidents".

    NARCIS (Netherlands)

    1976-01-01

    The study concerning the contact between a tyre and the road surface was conducted in three phases. In the first phase the first and second-order factors were separated. The factors: type of road surface, tyre type, tread depth, water depth, tyre pressure and tyre load were included in an

  15. Plasma rich in growth factors eye drops to treat secondary ocular surface disorders in patients with glaucoma

    Directory of Open Access Journals (Sweden)

    Sánchez-Avila RM

    2018-05-01

    Full Text Available Ronald M Sánchez-Avila,1 Jesus Merayo-Lloves,1 Maria Laura Fernández,1,2 Luis Alberto Rodríguez-Gutiérrez,1 Pedro Pablo Rodríguez-Calvo,1 Andres Fernández-Vega Cueto,1 Francisco Muruzabal,3,4 Gorka Orive,3–6 Eduardo Anitua3,4 1University Institute Fernández-Vega, Ophthalmological Research Foundation, University of Oviedo, Oviedo, Spain; 2Quilmes Eye Center, Buenos Aires, Argentina; 3University Institute for Regenerative Medicine and Oral Implantology (UIRMI, University of the Basque Country, Eduardo Anitua Foundation, Vitoria, Spain; 4Biotechnology Institute (BTI, Vitoria, Spain; 5Laboratory of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of the Basque Country, Vitoria, Spain; 6Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine, CIBER-BBN, Vitoria, Spain Purpose: To evaluate the efficacy and safety of plasma rich in growth factors (PRGF eye drops in patients with glaucoma with secondary ocular surface disorders (OSDs due to surgeries and topical hypotensive drugs use. Materials and methods: A retrospective case-series study design was used including six patients (eight eyes diagnosed with glaucoma who received surgical (nonpenetrating deep sclerectomy and/or trabeculectomy and medical treatments (hypotensive eye drops to control intraocular pressure (IOP and who developed secondary OSDs, unresponsive to conventional treatments. Patients were treated with PRGF eye drops (four times a day. Outcome measures were ocular surface disease index (OSDI, best-corrected visual acuity (BCVA, in logarithm of the minimum angle of resolution, visual analog scale (VAS, frequency and severity of symptoms, and IOP. The safety of the treatment was also evaluated. Results: Six patients (seven eyes with open-angle glaucoma and one eye with uveitic glaucoma treated with PRGF eye drops were evaluated. Mean age was 71 years (SD=7.2, range 58–79 years. Five were female and one was male. The mean

  16. Fundamental Factors Impacting the Stability of Phosphonate-Derivatized Ruthenium Polypyridyl Sensitizers Adsorbed on Metal Oxide Surfaces.

    Science.gov (United States)

    Raber, McKenzie; Brady, Matthew David; Troian-Gautier, Ludovic; Dickenson, John; Marquard, Seth L; Hyde, Jacob; Lopez, Santiago; Meyer, Gerald J; Meyer, Thomas J; Harrison, Daniel P

    2018-06-08

    A series of 18 ruthenium(II) polypyridyl complexes were synthesized and evaluated under electrochemically oxidative conditions, which generates the Ru(III) oxidation state and mimics the harsh conditions experienced during the kinetically-limited regime that can occur in dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthesis cells (DSPECs), to further develop fundamental insights into the factors governing molecular sensitizer surface stability in aqueous 0.1 M HClO4 (aq). Both desorption and oxidatively induced ligand substitution were observed on planar fluorine doped tin oxide, FTO, electrodes, with a dependence on the E1/2 Ru(III/II) redox potential dictating the comparative ratios of the processes. Complexes such as RuP4OMe (E1/2 = 0.91 vs Ag/AgCl) displayed virtually only desorption, while complexes such as RuPbpz (E1/2 > 1.62 V vs Ag/AgCl) displayed only chemical decomposition. Comparing isomers of 4,4'- and 5,5-disubstituted-2,2'-bipyridine ancillary polypyridyl ligands, a dramatic increase in the rate of desorption of the Ru(III) complexes was observed for the 5,5'-ligands. Nanoscopic indium doped tin oxide thin films, nanoITO, were also sensitized and analyzed with cyclic voltammetry, UV-Vis absorption spectroscopy, and XPS, allowing for further distinction of desorption versus ligand substitution processes. Desorption loss to bulk solution associated with the planar surface of FTO is essentially non-existent on nanoITO, where both desorption and ligand substitution are shut down with RuP4OMe. These results revealed that minimizing time spent in the oxidized form, incorporating electron donating groups, maximizing hydrophobicity, and minimizing molecular bulk near the adsorbed ligand are critical to optimizing the performance of ruthenium(II) polypyridyl complexes in dye-sensitized solar cell devices.

  17. Transforming growth factor (type beta) promotes the addition of chondroitin sulfate chains to the cell surface proteoglycan (syndecan) of mouse mammary epithelia

    OpenAIRE

    1989-01-01

    Cultured monolayers of NMuMG mouse mammary epithelial cells have augmented amounts of cell surface chondroitin sulfate glycosaminoglycan (GAG) when cultured in transforming growth factor-beta (TGF-beta), presumably because of increased synthesis on their cell surface proteoglycan (named syndecan), previously shown to contain chondroitin sulfate and heparan sulfate GAG. This increase occurs throughout the monolayer as shown using soluble thrombospondin as a binding probe. However, comparison o...

  18. A method for sensible heat flux model parameterization based on radiometric surface temperature and environmental factors without involving the parameter KB-1

    Science.gov (United States)

    Zhuang, Qifeng; Wu, Bingfang; Yan, Nana; Zhu, Weiwei; Xing, Qiang

    2016-05-01

    Sensible heat flux is a key component of land-atmosphere interaction. In most parameterizations it is calculated with surface-air temperature differences and total aerodynamic resistance to heat transfer (Rae) that is related to the KB-1 parameter. Suitable values are hard to obtain since KB-1 is related both to canopy characteristics and environmental conditions. In this paper, a parameterize method for sensible heat flux over vegetated surfaces (maize field and grass land in the Heihe river basin of northwest China) was proposed based on the radiometric surface temperature, surface resistance (Rs) and vapor pressures (saturated and actual) at the surface and the atmosphere above the canopy. A biophysics-based surface resistance model was revised to compute surface resistance with several environmental factors. The total aerodynamic resistance to heat transfer is directly calculated by combining the biophysics-based surface resistance and vapor pressures. One merit of this method is that the calculation of KB-1 can be avoided. The method provides a new way to estimate sensible heat flux over vegetated surfaces and its performance compares well to the LAS measured sensible heat and other empirical or semi-empirical KB-1 based estimations.

  19. Estimating the Analytical and Surface Enhancement Factors in Surface-Enhanced Raman Scattering (SERS): A Novel Physical Chemistry and Nanotechnology Laboratory Experiment

    Science.gov (United States)

    Pavel, Ioana E.; Alnajjar, Khadijeh S.; Monahan, Jennifer L.; Stahler, Adam; Hunter, Nora E.; Weaver, Kent M.; Baker, Joshua D.; Meyerhoefer, Allie J.; Dolson, David A.

    2012-01-01

    A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by…

  20. Characterization and molecular features of the cell surface receptor for human granulocyte-macrophage colony-stimulating factor

    International Nuclear Information System (INIS)

    Chiba, S.; Tojo, A.; Kitamura, T.; Urabe, A.; Miyazono, K.; Takaku, F.

    1990-01-01

    The receptors for human granulocyte-macrophage colony-stimulating factor (GM-CSF) on the surfaces of normal and leukemic myeloid cells were characterized using 125I-labeled bacterially synthesized GM-CSF. The binding was rapid, specific, time dependent, and saturable. Scatchard analysis of the 125I-GM-CSF binding to peripheral blood neutrophils indicated the presence of a single class of binding site (Kd = 99 +/- 21 pM; 2,304 +/- 953 sites/cell). However, for peripheral blood monocytes and two GM-CSF-responsive myeloid cell lines (U-937 and TF-1), the Scatchard plots were biphasic curvilinear, which were best fit by curves derived from two binding site model: one with high affinity (Kd1 = 10-40 pM) and the other with low affinity (Kd2 = 0.9-2.0 nM). For U-937 cells, the number of high-affinity receptors was 1,058 +/- 402 sites/cell and that of low-affinity receptors was estimated to be 10,834 +/- 2,396 sites/cell. Cross-linking studies yielded three major bands with molecular masses of 150 kDa, 115 kDa, and 95 kDa, which were displaced by an excess amount of unlabeled GM-CSF, suggesting 135-kDa, 100-kDa, and 80-kDa species for the individual components of the human GM-CSF receptor. These bands comigrated for different cell types including peripheral blood neutrophils, U-937 cells and TF-1 cells. In experiments using U-937 cells, only the latter two bands appeared to be labeled in a dose-dependent manner in a low-affinity state. These results suggest that the human GM-CSF receptor possibly forms a multichain complex

  1. Processing of cell-surface signalling anti-sigma factors prior to signal recognition is aconserved autoproteolytic mechanism that produces two functional domains.

    NARCIS (Netherlands)

    Bastiaansen, K.C.J.T.; Otero-Asman, J.R.; Luirink, J.; Bitter, W.; Llamas, M.A.

    2015-01-01

    Cell-surface signalling (CSS) enables Gram-negative bacteria to transduce an environmental signal into a cytosolic response. This regulatory cascade involves an outer membrane receptor that transmits the signal to an anti-sigma factor in the cytoplasmic membrane, allowing the activation of an

  2. High-resolution MRI using orbit surface coils for the evaluation of metastatic risk factors in 143 children with retinoblastoma. Part 1: MRI vs. histopathology

    Energy Technology Data Exchange (ETDEWEB)

    Sirin, Selma; Schlamann, Marc; Schweiger, Bernd; Goericke, Sophia L. [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Metz, Klaus A. [University Hospital Essen, Department of Pathology and Neuropathology, Essen (Germany); Bornfeld, Norbert; Holdt, Markus [University Hospital Essen, Department of Ophthalmology, Essen (Germany); Temming, Petra; Schuendeln, Michael M. [University Hospital Essen, Department of Pediatric Hematology and Oncology, Essen (Germany)

    2015-08-15

    A reliable detection of metastatic risk factors is important for children with retinoblastoma to choose the right therapeutic regimen. First studies using high-resolution magnetic resonance imaging (MRI) with orbit surface coils were promising. The aim of this study was therefore to evaluate the ability of high-resolution MRI to detect metastatic and especially advanced metastatic risk factors in a large group of children with retinoblastoma. One hundred forty-three consecutive children with retinoblastoma (148 enucleated eyes, 64 girls, 79 boys, mean age 19.7 ± 15.3) who received pretherapeutical high-resolution MRI with orbit surface coils on 1.5 T MR scanner systems between 2007 and 2012 and subsequent primary enucleation within 14 days were included in this retrospective study. Image analysis was performed by two neuroradiologists experienced in ocular imaging in consensus. Histopathology served as gold standard. Sensitivity/specificity for the detection of metastatic risk factors using high-resolution MRI with orbit surface coils were 60 %/88.7 % for postlaminar optic nerve infiltration, 65.5 %/95.6 % for choroidal invasion, 100 %/99.3 % for scleral invasion, and 100 %/100 % for peribulbar fat invasion, respectively. The results increased for the detection of advanced metastatic risk factors, 81.8 %/89.1 % for deep postlaminar optic nerve infiltration, 70.6 %/97.6 % for massive choroidal invasion. High-resolution MRI is clinically valuable for the detection of metastatic, especially of advanced metastatic risk factors in children with retinoblastoma. (orig.)

  3. Tooth surface loss, prevalence and associated risk factors among 12-14 years school children in Khartoum State, Sudan.

    Science.gov (United States)

    Sanhouri, N M; Ziada, H M; Ahmed, G I; Kamis, A H

    2010-12-01

    Investigate Tooth Surface Loss TSL, among 12-14 years school children in Khartoum State, Sudan; evaluate pattern, severity and determine relationship between TSL, dietary habits and socio-economical status. Cross sectional survey among primary public and private schools. Cluster sample of 1,138 12 to 14-year old students from both public and private school. Mild and moderate TSL was measured on buccal, lingual/palatal surfaces of maxillary and mandibular incisors and canines and occlusal, buccal, lingual/palatal surfaces of maxillary and mandibular premolars and molars. Surfaces scored according to criterion described by the National Survey of Child Dental Health. The prevalence of TSL was found to be 74%. Mild and moderate TSL was detected on palatal surfaces of maxillary central incisors followed by occlusal surfaces of mandibular molars. TSL into the pulp was not detected. A high prevalence of 74% was found with mild and moderate TSL with no pulpal involvement. There was an association between consumption of erosive foods and the prevalence of TSL. Socio-economic status and gender did not present significant differences.

  4. Welding-induced local maximum residual stress in heat affected zone of low-carbon austenitic stainless steel with machined surface layer and its influential factors

    International Nuclear Information System (INIS)

    Okano, Shigetaka; Ihara, Ryohei; Kanamaru, Daisuke; Mochizuki, Masahito

    2015-01-01

    In this study, the effects of work-hardening and pre-existing stress in the machined surface layer of low-carbon austenitic stainless steel on the welding-induced residual stress were experimentally investigated through the use of weld specimens with three different surface layers; as-cutout, mechanically-polished and electrolytically-polished. The high tensile and compressive stresses exist in the work-hardened surface layer of the as-cutout and mechanically-polished specimens, respectively. Meanwhile, no stress and work-hardened surface layer exist in the electrolytically-polished specimen. TIG bead-on-plate welding under the same welding heat input conditions was performed to introduce the residual stress into these specimens. Using these welded specimens, the distributions of welding-induced residual stress were measured by the X-ray diffraction method. Similarly, the distributions of hardness in welds were estimated by the Vickers hardness test. And then, these distributions were compared with one another. Based on the results, the residual stress in the weld metal (WM) is completely unaffected by the machined surface layer because the work-hardened surface layer disappears through the processes of melting and solidification during welding. The local maximum longitudinal tensile residual stress in the heat affected zone (HAZ) depends on the work-hardening but not on the existing stress, regardless of whether tensile or compressive, in the machined surface layer before welding. At the base metal far from WM and HAZ, the residual stress is formed by the addition of the welding-induced residual stress to the pre-existing stress in the machined surface layer before welding. The features of the welding-induced residual stress in low-carbon austenitic stainless steel with the machined surface layer and their influential factors were thus clarified. (author)

  5. High Surface-Enhanced Raman Scattering (SERS) Amplification Factor Obtained with Silver Printed Circuit Boards and the Influence of Phenolic Resins for the Characterization of the Pesticide Thiram.

    Science.gov (United States)

    Silva de Almeida, Francylaine; Bussler, Larissa; Marcio Lima, Sandro; Fiorucci, Antonio Rogério; da Cunha Andrade, Luis Humberto

    2016-07-01

    In this work, low-cost substrates with rough silver surfaces were prepared from commercial copper foil-covered phenolic board (CPB) and an aqueous solution of AgNO3, and were used for surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) measurements. A maximum SERS amplification factor of 1.2 × 10(7) was obtained for Rhodamine 6G (R6G), and use of the CPB resulted in a detection limit for Thiram pesticide of 0.5 µmol L(-1) The minimum detection level was limited by residual traces of phenolic groups that originated from the substrate resin, which became solubilized in the aqueous Ag(+) solution. It was found that the bands corresponding to the impurities had less influence in the Thiram analysis, which could be explained by the high affinity of sulfur for Ag surfaces. The influence of impurities in the SERS analyses therefore depended on the linkage between the rough silver surface and the analyte. The findings demonstrated the ease and effectiveness of using CPB to prepare a nanostructured surface for SERS. © The Author(s) 2016.

  6. The surface-associated elongation factor Tu is concealed for antibody binding on viable pneumococci and meningococci

    Czech Academy of Sciences Publication Activity Database

    Kolberg, J.; Hammerschmidt, S.; Frank, R.; Jonák, Jiří; Šanderová, Hana; Aase, A.

    2008-01-01

    Roč. 53, č. 2 (2008), s. 222-230 ISSN 0928-8244 R&D Projects: GA AV ČR KJB500520503 Institutional research plan: CEZ:AV0Z50520514; CEZ:AV0Z50200510 Keywords : Streptococcus pneumoniae * Neisseria meningitidis * elongation factor EF-Tu Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.972, year: 2008

  7. Further structural insights into the binding of complement factor H by complement regulator-acquiring surface protein 1 (CspA) of Borrelia burgdorferi

    International Nuclear Information System (INIS)

    Caesar, Joseph J. E.; Wallich, Reinhard; Kraiczy, Peter; Zipfel, Peter F.; Lea, Susan M.

    2013-01-01

    B. burgdorferi binds complement factor H using a dimeric surface protein, CspA (BbCRASP-1). Presented here is a new structure of CspA that suggests that there is a degree of flexibility between subunits which may have implications for complement regulator binding. Borrelia burgdorferi has evolved many mechanisms of evading the different immune systems across its range of reservoir hosts, including the capture and presentation of host complement regulators factor H and factor H-like protein-1 (FHL-1). Acquisition is mediated by a family of complement regulator-acquiring surface proteins (CRASPs), of which the atomic structure of CspA (BbCRASP-1) is known and shows the formation of a homodimeric species which is required for binding. Mutagenesis studies have mapped a putative factor H binding site to a cleft between the two subunits. Presented here is a new atomic structure of CspA which shows a degree of flexibility between the subunits which may be critical for factor H scavenging by increasing access to the binding interface and allows the possibility that the assembly can clamp around the bound complement regulators

  8. Study of the Relationships between the Spatial Extent of Surface Urban Heat Islands and Urban Characteristic Factors Based on Landsat ETM+ Data

    Directory of Open Access Journals (Sweden)

    Jinqu Zhang

    2008-11-01

    Full Text Available Ten cities with different population and urban sizes located in the Pearl River Delta, Guangdong Province, P.R. China were selected to study the relationships between the spatial extent of surface urban heat islands (SUHI and five urban characteristic factors such as urban size, development area, water proportion, mean NDVI (Normalized Vegetation Index and population density, etc. The spatial extent of SUHI was quantified by using the hot island area (HIA. All the cities are almost at the same latitude, showing similar climate and solar radiation, the influence of which could thus be eliminated during our computation and comparative study. The land surface temperatures (LST were retrieved from the data of Landsat 7 Enhanced Thematic Mapper Plus (ETM+ band 6 using a mono-window algorithm. A variance-segmenting method was proposed to compute HIA for each city from the retrieved LST. Factors like urban size, development area and water proportion were extracted directly from the classification images of the same ETM+ data and the population density factor is from the official census. Correlation and regression analyses were performed to study the relationships between the HIA and the related factors, and the results show that HIA is highly correlated to urban size (r=0.95, population density (r=0.97 and development area (r=0.83 in this area. It was also proved that a weak negative correlation existed between HIA and both mean NDVI and water proportion for each city. Linear functions between HIA and its related factors were established, respectively. The HIA can reflect the spatial extent and magnitude of the surface urban heat island effect, and can be used as reference in the urban planning.

  9. [Adsorption behavior and influence factors of p-nitroaniline on high surface area activated carbons prepared from plant stems].

    Science.gov (United States)

    Li, Kun-quan; Zheng, Zheng; Luo, Xing-zhang

    2010-08-01

    Low-cost and high surface area microporous activated carbons were prepared from Spartina alternilora and cotton stalk with KOH activation under the conditions of impregnation ratio of 3.0, activation temperature at 800 degrees C and activation time of 1.5 h. The adsorption behavior of p-nitroaniline on the activated carbons was investigated by batch sorption experiments. The influences of solution pH value, adsorbent dose and temperature were investigated. The adsorption isotherm and thermodynamic characteristics were also discussed. The Spartina alterniflora activated carbon (SA-AC) has a high surface area of 2825 m2 x g(-1) and a micropore volume of 1.192 cm3 x g(-1). The BET surface area and micropore volume of the cotton stalk activated carbon (CS-AC) are 2135 m2 x g(-1) and 1.011 cm3 x g(-1), respectively. The sorption experiments show that both the activated carbons have high sorption capacity for p-nitroaniline. The Langmuir maximum sorption amount was found to be 719 mg x g(-1) for SA-AC and 716 mg x g(-1) for CS-AC, respectively. The sorption was found to depend on solution pH, adsorbent dose, and temperature. The optimum pH for the removal of p-nitroaniline was found to be 7.0. The Freundlich model and Redlich-Peterson model can describe the experimental data effectively. The negative changes in free energy (delta G0) and enthalpy (delta H0) indicate that the sorption is a spontaneous and exothermic procedure. The negative values of the adsorption entropy delta S0 indicate that the mobility of p-nitroaniline on the carbon surface becomes more restricted as compared with that of those in solution.

  10. Surface-plasmon-induced modification on the spontaneous emission spectrum via subwavelength-confined anisotropic Purcell factor.

    Science.gov (United States)

    Gu, Ying; Wang, Luojia; Ren, Pan; Zhang, Junxiang; Zhang, Tiancai; Martin, Olivier J F; Gong, Qihuang

    2012-05-09

    The mechanism of using the anisotropic Purcell factor to control the spontaneous emission linewidths in a four-level atom is theoretically demonstrated; if the polarization angle bisector of the two dipole moments lies along the axis of large/small Purcell factor, destructive/constructive interference narrows/widens the fluorescence center spectral lines. Large anisotropy of the Purcell factor, confined in the subwavelength optical mode volume, leads to rapid spectral line narrowing of atom approaching a metallic nanowire, nanoscale line width pulsing following periodically varying decay rates near a periodic metallic nanostructure, and dramatic modification on the spontaneous emission spectrum near a custom-designed resonant plasmon nanostructure. The combined system opens a good perspective for applications in ultracompact active quantum devices.

  11. High-resolution MRI using orbit surface coils for the evaluation of metastatic risk factors in 143 children with retinoblastoma. Part 2: new vs. old imaging concept

    Energy Technology Data Exchange (ETDEWEB)

    Sirin, Selma; Schlamann, Marc; Schweiger, Bernd; Goericke, Sophia L. [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Metz, Klaus A. [University Hospital Essen, Department of Pathology and Neuropathology, Essen (Germany); Bornfeld, Norbert; Holdt, Markus [University Hospital Essen, Department of Ophthalmology, Essen (Germany); Temming, Petra; Schuendeln, Michael M. [University Hospital Essen, Department of Pediatric Hematology and Oncology, Essen (Germany)

    2015-08-15

    High-resolution magnetic resonance imaging (MRI) is recommended for the evaluation of metastatic risk factors in children with retinoblastoma according to recent guidelines. The aim of this study was to compare diagnostic accuracy of a new imaging concept with two orbit surface coils to that of an old imaging concept with one orbit surface coil. One hundred forty-three patients (148 eyes, 64 girls, 79 boys) underwent high-resolution MRI on 1.5 T scanners using orbit surface coils. The old imaging concept (one orbit surface coil focusing on the (most) effected eye additionally to the standard head coil) was used in 100 patients/103 eye; the new imaging concept (two orbit surface coils (each focusing on one eye) additionally to the standard head coil) in 43 patients/45 eyes. Image analysis was performed by two neuroradiologists in consensus. Histopathology served as gold standard. Detection rate for choroidal invasion was higher for the new compared to that for the old imaging concept (sensitivity/specificity 87.5/94.6 % vs. 57.1/96.1 % for choroidal invasion and 100/97.5 % vs. 58.3/97.7 % for massive choroidal invasion, respectively). Sensitivity and specificity for the detection of postlaminar optic nerve infiltration, peribulbar fat, and scleral invasion were comparable in both imaging concepts; however positive predictive value was higher in the new imaging concept (new vs. old imaging concept: 60 vs. 31.6 % for postlaminar and deep postlaminar optic nerve infiltration, respectively, and 100 vs. 66.7 % for scleral invasion). The new imaging concept shows a trend towards improving the accuracy of detecting metastatic risk factors in children with retinoblastoma and is therefore recommended for pretherapeutic imaging and follow-up. (orig.)

  12. High-resolution MRI using orbit surface coils for the evaluation of metastatic risk factors in 143 children with retinoblastoma. Part 2: new vs. old imaging concept

    International Nuclear Information System (INIS)

    Sirin, Selma; Schlamann, Marc; Schweiger, Bernd; Goericke, Sophia L.; Metz, Klaus A.; Bornfeld, Norbert; Holdt, Markus; Temming, Petra; Schuendeln, Michael M.

    2015-01-01

    High-resolution magnetic resonance imaging (MRI) is recommended for the evaluation of metastatic risk factors in children with retinoblastoma according to recent guidelines. The aim of this study was to compare diagnostic accuracy of a new imaging concept with two orbit surface coils to that of an old imaging concept with one orbit surface coil. One hundred forty-three patients (148 eyes, 64 girls, 79 boys) underwent high-resolution MRI on 1.5 T scanners using orbit surface coils. The old imaging concept (one orbit surface coil focusing on the (most) effected eye additionally to the standard head coil) was used in 100 patients/103 eye; the new imaging concept (two orbit surface coils (each focusing on one eye) additionally to the standard head coil) in 43 patients/45 eyes. Image analysis was performed by two neuroradiologists in consensus. Histopathology served as gold standard. Detection rate for choroidal invasion was higher for the new compared to that for the old imaging concept (sensitivity/specificity 87.5/94.6 % vs. 57.1/96.1 % for choroidal invasion and 100/97.5 % vs. 58.3/97.7 % for massive choroidal invasion, respectively). Sensitivity and specificity for the detection of postlaminar optic nerve infiltration, peribulbar fat, and scleral invasion were comparable in both imaging concepts; however positive predictive value was higher in the new imaging concept (new vs. old imaging concept: 60 vs. 31.6 % for postlaminar and deep postlaminar optic nerve infiltration, respectively, and 100 vs. 66.7 % for scleral invasion). The new imaging concept shows a trend towards improving the accuracy of detecting metastatic risk factors in children with retinoblastoma and is therefore recommended for pretherapeutic imaging and follow-up. (orig.)

  13. Improving the robustness of Surface Enhanced Raman Spectroscopy based sensors by Bayesian Non-negative Matrix Factorization

    DEFF Research Database (Denmark)

    Alstrøm, Tommy Sonne; Frøhling, Kasper Bayer; Larsen, Jan

    2014-01-01

    a Bayesian Non-negative Matrix Factorization (NMF) approach to identify locations of target molecules. The proposed method is able to successfully analyze the spectra and extract the target spectrum. A visualization of the loadings of the basis vector is created and the results show a clear SNR enhancement...

  14. Electron-beam induced amorphization of stishovite: Silicon-coordination change observed using Si K-edge extended electron energy-loss fine structure

    International Nuclear Information System (INIS)

    Aken, P.A. van; Sharp, T.G.; Seifert, F.

    1998-01-01

    The analysis of the extended energy-loss fine structure (EXELFS) of the Si K-edge for sixfold-coordinated Si in synthetic stishovite and fourfold-coordinated Si in natural α-quartz is reported by using electron energy-loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM). The stishovite Si K-edge EXELFS spectra were measured as a time-dependent series to document irradiation-induced amorphization. The amorphization was also investigated through the change in Si K- and O K-edge energy-loss near edge structure (ELNES). For α-quartz, in contrast to stishovite, electron irradiation-induced vitrification, produced no detectable changes of the EXELFS. The Si K-edge EXELFS were analysed with the classical extended X-ray absorption fine structure (EXAFS) treatment and compared to ab initio curve-waved multiple-scattering (MS) calculations of EXAFS spectra for stishovite and α-quartz. Highly accurate information on the local atomic environment of the silicon atoms during the irradiation-induced amorphization of stishovite is obtained from the EXELFS structure parameters The mean Si-O bond distance R and mean Si coordination number N changes from R=0.1775 nm and N=6 for stishovite through a disordered intermediate state (R∼0.172 nm and N∼5) to R∼0.167 nm and N∼4.5 for a nearly amorphous state similar to α-quartz (R=0.1609 nm and N=4). During the amorphization process, the Debye-Waller factor (DWF) passes through a maximum value of σ N 2 ∼83.8pm 2 as it changes from σ st 2 =51.8pm 2 for sixfold to σ qu 2 =18.4pm 2 for fourfold coordination of Si. This increase in Debye-Waller factor indicates an increase in mean-square relative displacement (MSRD) between the central silicon atom and its oxygen neighbours. Using the EXELFS data for amorphization, a new method is developed to derive the relative amounts of Si coordinations in high-pressure minerals with mixed coordination. For the radiation-induced amorphization process of

  15. Stress-intensity factors for a thick-walled cylinder containing an annular imbedded or external or internal surface crack

    Science.gov (United States)

    Erdol, R.; Erdogan, F.

    1976-01-01

    The elastostatic axisymmetric problem for a long thick-walled cylinder containing a ring-shaped internal or edge crack is considered. Using the standard transform technique the problem is formulated in terms of an integral equation which has a simple Cauchy kernel for the internal crack and a generalized Cauchy kernel for the edge crack as the dominant part. As examples the uniform axial load and the steady-state thermal stress problems have been solved and the related stress intensity factors have been calculated. Among other findings the results show that in the cylinder under uniform axial stress containing an internal crack the stress intensity factor at the inner tip is always greater than that at the outer tip for equal net ligament thicknesses and in the cylinder with an edge crack which is under a state of thermal stress the stress intensity factor is a decreasing function of the crack depth, tending to zero as the crack depth approaches the wall thickness.

  16. McWRI1, a transcription factor of the AP2/SHEN family, regulates the biosynthesis of the cuticular waxes on the apple fruit surface under low temperature

    Science.gov (United States)

    Ji, Qianlong; Zhang, Kezhong; Yang, Mingfeng

    2017-01-01

    Cuticular waxes of plant and organ surfaces play an important role in protecting plants from biotic and abiotic stress and extending the freshness, storage time and shelf life in the post-harvest agricultural products. WRI1, a transcription factor of AP2/SHEN families, had been found to trigger the related genes taking part in the biosynthesis of seed oil in many plants. But whether WRI1 is involved in the biosynthesis of the cuticular waxes on the Malus fruits surface has been unclear. We investigated the changes of wax composition and structure, the related genes and WRI1 expression on Malus asiatica Nakai and sieversii fruits with the low temperature treatments, found that low temperature induced the up-regulated expression of McWRI1, which promoted gene expression of McKCS, McLACs and McWAX in very-long-chain fatty acid biosynthesis pathway, resulting in the accumulation of alkanes component and alteration of wax structure on the fruit surface. Corresponding results were verified in McWRI1 silenced by VIGS, and WRI1 silenced down-regulated the related genes on two kinds of fruits, it caused the diversity alteration in content of some alkanes, fatty acid and ester component in two kinds of fruits. We further conducted Y1H assay to find that McWRI1 transcription factor activated the promoter of McKCS, McLAC and McWAX to regulate their expression. These results demonstrated that McWRI1 is involved in regulating the genes related synthesis of very long chain fatty acid on surface of apple fruits in storage process, providing a highlight for improvement of the modified atmosphere storage of apple fruits. PMID:29073205

  17. Disease-linked mutations in factor H reveal pivotal role of cofactor activity in self-surface-selective regulation of complement activation.

    Science.gov (United States)

    Kerr, Heather; Wong, Edwin; Makou, Elisavet; Yang, Yi; Marchbank, Kevin; Kavanagh, David; Richards, Anna; Herbert, Andrew P; Barlow, Paul N

    2017-08-11

    Spontaneous activation enables the complement system to respond very rapidly to diverse threats. This activation is efficiently suppressed by complement factor H (CFH) on self-surfaces but not on foreign surfaces. The surface selectivity of CFH, a soluble protein containing 20 complement-control protein modules (CCPs 1-20), may be compromised by disease-linked mutations. However, which of the several functions of CFH drives this self-surface selectivity remains unknown. To address this, we expressed human CFH mutants in Pichia pastoris We found that recombinant I62-CFH (protective against age-related macular degeneration) and V62-CFH functioned equivalently, matching or outperforming plasma-derived CFH, whereas R53H-CFH, linked to atypical hemolytic uremic syndrome (aHUS), was defective in C3bBb decay-accelerating activity (DAA) and factor I cofactor activity (CA). The aHUS-linked CCP 19 mutant D1119G-CFH had virtually no CA on (self-like) sheep erythrocytes ( E S ) but retained DAA. The aHUS-linked CCP 20 mutant S1191L/V1197A-CFH (LA-CFH) had dramatically reduced CA on E S but was less compromised in DAA. D1119G-CFH and LA-CFH both performed poorly at preventing complement-mediated hemolysis of E S PspCN, a CFH-binding Streptococcus pneumoniae protein domain, binds CFH tightly and increases accessibility of CCPs 19 and 20. PspCN did not improve the DAA of any CFH variant on E S Conversely, PspCN boosted the CA, on E S , of I62-CFH, R53H-CFH, and LA-CFH and also enhanced hemolysis protection by I62-CFH and LA-CFH. We conclude that CCPs 19 and 20 are critical for efficient CA on self-surfaces but less important for DAA. Exposing CCPs 19 and 20 with PspCN and thus enhancing CA on self-surfaces may reverse deficiencies of some CFH variants. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Improved Formula for the Stress Intensity Factor of Semi-Elliptical Surface Cracks in Welded Joints under Bending Stress

    Science.gov (United States)

    Peng, Yang; Wu, Chao; Zheng, Yifu; Dong, Jun

    2017-01-01

    Welded joints are prone to fatigue cracking with the existence of welding defects and bending stress. Fracture mechanics is a useful approach in which the fatigue life of the welded joint can be predicted. The key challenge of such predictions using fracture mechanics is how to accurately calculate the stress intensity factor (SIF). An empirical formula for calculating the SIF of welded joints under bending stress was developed by Baik, Yamada and Ishikawa based on the hybrid method. However, when calculating the SIF of a semi-elliptical crack, this study found that the accuracy of the Baik-Yamada formula was poor when comparing the benchmark results, experimental data and numerical results. The reasons for the reduced accuracy of the Baik-Yamada formula were identified and discussed in this paper. Furthermore, a new correction factor was developed and added to the Baik-Yamada formula by using theoretical analysis and numerical regression. Finally, the predictions using the modified Baik-Yamada formula were compared with the benchmark results, experimental data and numerical results. It was found that the accuracy of the modified Baik-Yamada formula was greatly improved. Therefore, it is proposed that this modified formula is used to conveniently and accurately calculate the SIF of semi-elliptical cracks in welded joints under bending stress. PMID:28772527

  19. ALTERED EXPRESSION OF SURFACE RECEPTORS AT EA.HY926 ENDOTHELIAL CELL LINE INDUCED WITH PLACENTAL SECRETORY FACTORS

    Directory of Open Access Journals (Sweden)

    O. I. Stepanova

    2012-01-01

    Full Text Available Abstract. Placental cell populations produce a great variety of angiogenic factors and cytokines than control angiogenesis in placenta. Functional regulation of endothelial cells proceeds via modulation of endothelial cell receptors for endogenous angiogenic and apoptotic signals. Endothelial phenotype alteration during normal pregnancy and in cases of preclampsia is not well understood. The goal of this investigation was to evaluate altered expression of angiogenic and cytokine receptors at EA.hy926 endothelial cells under the influence of placental tissue supernatants. Normal placental tissue supernatants from 1st and 3rd trimesters, and pre-eclamptic placental tissue supernatants (3rd trimester stimulated angiogenic and cytokine receptors expression by the cultured endothelial cells, as compared with their background expression. Tissue supernatants from placental samples of 3rd trimester caused a decreased expression of angiogenic and cytokine receptors by endothelial cells, thus reflecting maturation of placental vascular system at these terms. Supernatants from preeclamptic placental tissue induced an increase of CD119 expression, in comparison with normal placental supernatants from the 3rd trimester. This finding suggests that IFNγ may be a factor of endothelial activation in pre-eclampsia. The study was supported by grants ГК №02.740.11.0711, НШ-3594.2010.7., and МД-150.2011.7.

  20. Tracking polychlorinated biphenyls (PCBs) congener patterns in Newark Bay surface sediment using principal component analysis (PCA) and positive matrix factorization (PMF).

    Science.gov (United States)

    Saba, Tarek; Su, Steave

    2013-09-15

    PCB congener data for Newark Bay surface sediments were analyzed using PCA and PMF, and relationships between the outcomes from these two techniques were explored. The PCA scores plot separated the Lower Passaic River Mouth samples from North Newark Bay, thus indicating dissimilarity. Although PCA was able to identify subareas in the Bay system with specific PCB congener patterns (e.g., higher chlorinated congeners in Elizabeth River), further conclusions reading potential PCB source profiles or potential upland source areas were not clear for the PCA scores plot. PMF identified five source factors, and explained the Bay sample congener profiles as a mix of these Factors. This PMF solution was equivalent to (1) defining an envelope that encompasses all samples on the PCA scores plot, (2) defining source factors that plot on that envelope, and (3) explaining the congener profile for each Bay sediment sample (inside the scores plot envelope) as a mix of factors. PMF analysis allowed identifying characteristic features in the source factor congener distributions that allowed tracking of source factors to shoreline areas where PCB inputs to the Bay may have originated. The combined analysis from PCA and PMF showed that direct discharges to the Bay are likely the dominant sources of PCBs to the sediment. Review of historical upland activities and regulatory files will be needed, in addition to the PCA and PMF analysis, to fully reconstruct the history of operations and PCB releases around the Newark Bay area that impacted the Bay sediment. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Study of the factors influencing the metals solubilisation from a mixture of waste batteries by response surface methodology.

    Science.gov (United States)

    Tanong, Kulchaya; Coudert, Lucie; Chartier, Myriam; Mercier, Guy; Blais, Jean-François

    2017-12-01

    This paper presents an innovative process for the recovery of valuable metals from a mixture of spent batteries. Different types of batteries, including alkaline, zinc-carbon (Zn-C), nickel cadmium (Ni-Cd), nickel metal hydride (Ni-MH), lithium ion (Li-ion) and lithium metallic (Li-M) batteries, were mixed according to the proportion of the Canadian sales of batteries. A Box-Behnken design was applied to find the optimum leaching conditions allowing a maximum of valuable metal removals from a mixture of spent batteries in the presence of an inorganic acid and a reducing agent. The results highlighted the positive effect of sodium metabisulfite on the performance of metals removal, especially for Mn. The solid/liquid ratio and the concentration of H 2 SO 4 were the main factors affecting the leaching behavior of valuable metals (Zn, Mn, Cd, Ni) present in spent batteries. Finally, the optimum leaching conditions were found as follows: one leaching step, solid/liquid ratio = 10.9%, [H 2 SO 4 ] = 1.34 M, sodium metabisulfite (Na 2 S 2 O 5 ) = 0.45 g/g of battery powder and retention time = 45 min. Under such conditions, the removal yields achieved were 94% for Mn, 81% for Cd, 99% for Zn, 96% for Co and 68% for Ni.

  2. The relationship of chromophoric dissolved organic matter parallel factor analysis fluorescence and polycyclic aromatic hydrocarbons in natural surface waters.

    Science.gov (United States)

    Li, Sijia; Chen, Ya'nan; Zhang, Jiquan; Song, Kaishan; Mu, Guangyi; Sun, Caiyun; Ju, Hanyu; Ji, Meichen

    2018-01-01

    Polycyclic aromatic hydrocarbons (PAHs), a large group of persistent organic pollutants (POPs), have caused wide environmental pollution and ecological effects. Chromophoric dissolved organic matter (CDOM), which consists of complex compounds, was seen as a proxy of water quality. An attempt was made to understand the relationships of CDOM absorption parameters and parallel factor analysis (PARAFAC) components with PAHs under seasonal variation in the riverine, reservoir, and urban waters of the Yinma River watershed in 2016. These different types of water bodies provided wide CDOM and PAHs concentration ranges with CDOM absorption coefficients at a wavelength of 350 nm (a CDOM (350)) of 1.17-20.74 m -1 and total PAHs of 0-1829 ng/L. CDOM excitation-emission matrix (EEM) presented two fluorescent components, e.g., terrestrial humic-like (C1) and tryptophan-like (C2) were identified using PARAFAC. Tryptophan-like associated protein-like fluorescence often dominates the EEM signatures of sewage samples. Our finding is that seasonal CDOM EEM-PARAFAC and PAHs concentration showed consistent tendency indicated that PAHs were un-ignorable pollutants. However, the disparities in seasonal CDOM-PAH relationships relate to the similar sources of CDOM and PAHs, and the proportion of PAHs in CDOM. Overlooked and poorly appreciated, quantifying the relationship between CDOM and PAHs has important implications, because these results simplify ecological and health-based risk assessment of pollutants compared to the traditional chemical measurements.

  3. Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China - Part 1: Overall trends and characteristics

    Science.gov (United States)

    Xu, Wanyun; Lin, Weili; Xu, Xiaobin; Tang, Jie; Huang, Jianqing; Wu, Hao; Zhang, Xiaochun

    2016-05-01

    Tropospheric ozone is an important atmospheric oxidant, greenhouse gas and atmospheric pollutant at the same time. The oxidation capacity of the atmosphere, climate, human and vegetation health can be impacted by the increase of the ozone level. Therefore, long-term determination of trends of baseline ozone is highly needed information for environmental and climate change assessment. So far, studies on the long-term trends of ozone at representative sites are mainly available for European and North American sites. Similar studies are lacking for China and many other developing countries. Measurements of surface ozone were carried out at a baseline Global Atmospheric Watch (GAW) station in the north-eastern Tibetan Plateau region (Mt Waliguan, 36°17' N, 100°54' E, 3816 m a.s.l.) for the period of 1994 to 2013. To uncover the variation characteristics, long-term trends and influencing factors of surface ozone at this remote site in western China, a two-part study has been carried out, with this part focusing on the overall characteristics of diurnal, seasonal and long-term variations and the trends of surface ozone. To obtain reliable ozone trends, we performed the Mann-Kendall trend test and the Hilbert-Huang transform (HHT) analysis on the ozone data. Our results confirm that the mountain-valley breeze plays an important role in the diurnal cycle of surface ozone at Waliguan, resulting in higher ozone values during the night and lower ones during the day, as was previously reported. Systematic diurnal and seasonal variations were found in mountain-valley breezes at the site, which were used in defining season-dependent daytime and nighttime periods for trend calculations. Significant positive trends in surface ozone were detected for both daytime (0.24 ± 0.16 ppbv year-1) and nighttime (0.28 ± 0.17 ppbv year-1). The largest nighttime increasing rate occurred in autumn (0.29 ± 0.11 ppbv year-1), followed by spring (0.24 ± 0.12 ppbv year-1), summer (0.22 ± 0

  4. Engineering of PDMS surfaces for use in microsystems for capture and isolation of complex and biomedically important proteins: epidermal growth factor receptor as a model system.

    Science.gov (United States)

    Lowe, Aaron M; Ozer, Byram H; Wiepz, Gregory J; Bertics, Paul J; Abbott, Nicholas L

    2008-08-01

    Elastomers based on poly(dimethylsiloxane) (PDMS) are promising materials for fabrication of a wide range of microanalytical systems due to their mechanical and optical properties and ease of processing. To date, however, quantitative studies that demonstrate reliable and reproducible methods for attachment of binding groups that capture complex receptor proteins of relevance to biomedical applications of PDMS microsystems have not been reported. Herein we describe methods that lead to the reproducible capture of a transmembrane protein, the human epidermal growth factor (EGF) receptor, onto PDMS surfaces presenting covalently immobilized antibodies for EGF receptor, and subsequent isolation of the captured receptor by mechanical transfer of the receptor onto a chemically functionalized surface of a gold film for detection. This result is particularly significant because the physical properties of transmembrane proteins make this class of proteins a difficult one to analyze. We benchmark the performance of antibodies to the human EGF receptor covalently immobilized on PDMS against the performance of the same antibodies physisorbed to conventional surfaces utilized in ELISA assays through the use of EGF receptor that was (32)P-radiolabeled in its autophosphorylation domain. These results reveal that two pan-reactive antibodies for the EGF receptor (clones H11 and 111.6) and one phosphospecific EGF receptor antibody (clone pY1068) capture the receptor on both PDMS and ELISA plates. When using H11 antibody to capture EGF receptor and subsequent treatment with a stripping buffer (NaOH and sodium dodecylsulfate) to isolate the receptor, the signal-to-background obtained using the PDMS surface was 82 : 1, exceeding the signal-to-background measured on the ELISA plate (<48 : 1). We also characterized the isolation of captured EGF receptor by mechanical contact of the PDMS surface with a chemically functionalized gold film. The efficiency of mechanical transfer of the

  5. The Impacts of Various Environments Factors and Adaptive Management Strategies on Food Crops in the 21st Century Based on a Land Surface Model

    Science.gov (United States)

    Jain, A. K.; Lin, T. S.; Lawrence, P.; Kheshgi, H. S.

    2017-12-01

    Environmental factors - characterized by increasing levels of CO2, and changes in temperature and precipitation patterns - present potential risks to global food supply. To date, understanding of environmental factors' effects on crop production remains uncertain due to (1) uncertainties in projected trends of these factors and their spatial and temporal variability; (2) uncertainties in the physiological, genetic and molecular basis of crop adaptation to adaptive management practices (e.g. change in planting time, irrigation and N fertilization etc.) and (3) uncertainties in current land surface models to estimate the response of crop production to changes in environmental factors and management strategies. In this study we apply a process-based land surface model, the Integrated Science Assessment model (ISAM), to assess the impact of various environmental factors and management strategies on the production of row crops (corn, soybean and wheat) at regional and global scales. Results are compared to corresponding simulations performed with the crop model in the Community Land Model (CLM4.5). Each model is driven with historical atmospheric forcing data (1901-2005), and projected atmospheric forcing data under RCP 4.5 or RCP 8.5 (2006-2100) from CESM CMIP5 simulations to estimate the effects of different climate change projections on potential productivity of food crops at a global scale. For each set of atmospheric forcing data, production of each crop is simulated with and without inclusion of adaptive management practices (e.g. application of irrigation, N fertilization, change in planting time and crop cultivars etc.) to assess the effect of adaptation on projected crop production over the 21st century. In detail, three questions are addressed: (1) what is the impact of different climate change projections on global crop production; (2) what is the effect of adaptive management practices on projected crop production; and (3) how do differences in model

  6. Hepatitis B vaccination coverage and risk factors associated with incomplete vaccination of children born to hepatitis B surface antigen-positive mothers, Denmark, 2006 to 2010.

    Science.gov (United States)

    Kunoee, Asja; Nielsen, Jens; Cowan, Susan

    2016-01-01

    In Denmark, universal screening of pregnant women for hepatitis B has been in place since November 2005, with the first two years as a trial period with enhanced surveillance. It is unknown what the change to universal screening without enhanced surveillance has meant for vaccination coverage among children born to hepatitis B surface antigen (HBsAg)-positive mothers and what risk factors exist for incomplete vaccination. This retrospective cohort study included 699 children of mothers positive for HBsAg. Information on vaccination and risk factors was collected from central registers. In total, 93% (651/699) of the children were vaccinated within 48 hours of birth, with considerable variation between birthplaces. Only 64% (306/475) of the children had received all four vaccinations through their general practitioner (GP) at the age of two years, and 10% (47/475) of the children had received no hepatitis B vaccinations at all. Enhanced surveillance was correlated positively with coverage of birth vaccination but not with coverage at the GP. No or few prenatal examinations were a risk factor for incomplete vaccination at the GP. Maternity wards and GPs are encouraged to revise their vaccination procedures and routines for pregnant women, mothers with chronic HBV infection and their children.

  7. Distributions and contamination assessment of heavy metals in the surface sediments of western Laizhou Bay: Implications for the sources and influencing factors.

    Science.gov (United States)

    Zhang, Pan; Hu, Rijun; Zhu, Longhai; Wang, Peng; Yin, Dongxiao; Zhang, Lianjie

    2017-06-15

    Heavy metals (Cu, Pb, Cr, Cd and As) contents in surface sediments from western Laizhou Bay were analysed to evaluate the spatial distribution pattern and their contamination level. As was mainly concentrated in the coastal area near the estuaries and the other metals were mainly concentrated in the central part of the study area. The heavy metals were present at unpolluted levels overall evaluated by the sediment quality guidelines and geoaccumulation index. Principal component analysis suggest that Cu, Pb and Cd were mainly sourced from natural processes and As was mainly derived from anthropogenic inputs. Meanwhile, Cr originated from both natural processes and anthropogenic contributions. Tidal currents, sediments and human activities were important factors affecting the distribution of heavy metals. The heavy metal environment was divided into four subareas to provide a reference for understanding the distribution and pollution of heavy metals in the estuary-bay system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Optimization of Methods for Articular Cartilage Surface Tissue Engineering: Cell Density and Transforming Growth Factor Beta Are Critical for Self-Assembly and Lubricin Secretion.

    Science.gov (United States)

    Iwasa, Kenjiro; Reddi, A Hari

    2017-07-01

    Lubricin/superficial zone protein (SZP)/proteoglycan4 (PRG4) plays an important role in boundary lubrication in articular cartilage. Lubricin is secreted by superficial zone chondrocytes and synoviocytes of the synovium. The specific objective of this investigation is to optimize the methods for tissue engineering of articular cartilage surface. The aim of this study is to investigate the effect of cell density on the self-assembly of superficial zone chondrocytes and lubricin secretion as a functional assessment. Superficial zone chondrocytes were cultivated as a monolayer at low, medium, and high densities. Chondrocytes at the three different densities were treated with transforming growth factor beta (TGF-β)1 twice a week or daily, and the accumulated lubricin in the culture medium was analyzed by immunoblots and quantitated by enzyme-linked immunosorbent assay (ELISA). Cell numbers in low and medium densities were increased by TGF-β1; whereas cell numbers in high-density cell cultures were decreased by twice-a-week treatment of TGF-β1. On the other hand, the cell numbers were maintained by daily TGF-β treatment. Immunoblots and quantitation of lubricin by ELISA analysis indicated that TGF-β1 stimulated lubricin secretion by superficial zone chondrocytes at all densities with twice-a-week TGF-β treatment. It is noteworthy that the daily treatment of TGF-β1 increased lubricin much higher compared with twice-a-week treatment. These data demonstrate that daily treatment is optimal for the TGF-β1 response in a higher density of monolayer cultures. These findings have implications for self-assembly of surface zone chondrocytes of articular cartilage for application in tissue engineering of articular cartilage surface.

  9. Daily changes of radon concentration in soil gas under influence of atmospheric factors: room temperature, soil surface temperature and relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Lara, Evelise G.; Oliveira, Arno Heeren de, E-mail: evelise.lara@gmail.com, E-mail: heeren@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Rocha, Zildete; Rios, Francisco Javier, E-mail: rochaz@cdtn.br, E-mail: javier@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    This work aims at relating the daily change in the radon concentration in soil gas in a Red Yellow Acrisol (SiBCS) under influence of atmospheric factors: room temperature, soil surface temperature and relative humidity. The {sup 226}Ra, {sup 232}Th, U content and permeability were also performed. The measurements of radon soil gas were carried out by using an AlphaGUARD monitor. The {sup 226}Ra activity concentration was made by Gamma Spectrometry (HPGe); the permeability was carried out using the RADON-JOK permeameter and ICP-MS analysis to {sup 232}Th and U content. The soil permeability is 5.0 x 10{sup -12}, which is considered average. The {sup 226}Ra (22.2 ± 0.3 Bq.m{sup -3}); U content (73.4 ± 3.6 Bq.kg{sup -1}) and {sup 232}Th content (55.3 ± 4.0 Bq.kg{sup -1}) were considered above of average concentrations, according to mean values for soils typical (~ 35.0 Bq.kg{sup -1}) by UNSCEAR. The results showed a difference of 26.0% between the highest and the lowest concentration of radon in soil gas: at midnight (15.5 ± 1.0 kBq.m{sup -3}) and 3:00 pm, the highest mean radon concentration (21.0 ± 1.0 kBq.m{sup -3}). The room temperature and surface soil temperature showed equivalent behavior and the surface soil temperature slightly below room temperature during the entire monitoring time. Nevertheless, the relative humidity showed the highest cyclical behavior, showing a higher relationship with the radon concentration in soil gas. (author)

  10. Daily changes of radon concentration in soil gas under influence of atmospheric factors: room temperature, soil surface temperature and relative humidity

    International Nuclear Information System (INIS)

    Lara, Evelise G.; Oliveira, Arno Heeren de

    2015-01-01

    This work aims at relating the daily change in the radon concentration in soil gas in a Red Yellow Acrisol (SiBCS) under influence of atmospheric factors: room temperature, soil surface temperature and relative humidity. The 226 Ra, 232 Th, U content and permeability were also performed. The measurements of radon soil gas were carried out by using an AlphaGUARD monitor. The 226 Ra activity concentration was made by Gamma Spectrometry (HPGe); the permeability was carried out using the RADON-JOK permeameter and ICP-MS analysis to 232 Th and U content. The soil permeability is 5.0 x 10 -12 , which is considered average. The 226 Ra (22.2 ± 0.3 Bq.m -3 ); U content (73.4 ± 3.6 Bq.kg -1 ) and 232 Th content (55.3 ± 4.0 Bq.kg -1 ) were considered above of average concentrations, according to mean values for soils typical (~ 35.0 Bq.kg -1 ) by UNSCEAR. The results showed a difference of 26.0% between the highest and the lowest concentration of radon in soil gas: at midnight (15.5 ± 1.0 kBq.m -3 ) and 3:00 pm, the highest mean radon concentration (21.0 ± 1.0 kBq.m -3 ). The room temperature and surface soil temperature showed equivalent behavior and the surface soil temperature slightly below room temperature during the entire monitoring time. Nevertheless, the relative humidity showed the highest cyclical behavior, showing a higher relationship with the radon concentration in soil gas. (author)

  11. Suppressed beta relaxations and reduced heat capacity in ultrastable organic glasses prepared by physical vapor deposition

    Science.gov (United States)

    Ediger, Mark

    Glasses play an important role in technology as a result of their macroscopic homogeneity (e.g., the clarity of window glass) and our ability to tune properties through composition changes. A problem with liquid-cooled glasses is that they exhibit marginal kinetic stability and slowly evolve towards lower energy glasses and crystalline states. In contrast, we have shown that physical vapor deposition can prepare glasses with very high kinetic stability. These materials have properties expected for ``million-year-old'' glasses, including high density, low enthalpy, and high mechanical moduli. We have used nanocalorimetry to show that these high stability glasses have lower heat capacities than liquid-cooled glasses for a number of molecular systems. Dielectric relaxation has been used to show that the beta relaxation can be suppressed by nearly a factor of four in vapor-deposited toluene glasses, indicating a very tight packing environment. Consistent with this view, computer simulations of high stability glasses indicate reduced Debye-Waller factors. These high stability materials raise interesting questions about the limiting properties of amorphous packing arrangements.

  12. Atomic vibration amplitudes in fcc and hcp 4He through x-ray diffraction measurements

    International Nuclear Information System (INIS)

    Venkataraman, C.T.; Simmons, R.O.

    2003-01-01

    Atomic vibration amplitudes in dense fcc and hcp 4 He crystals have been measured using synchrotron x rays from the dependence of integrated Bragg intensities up to wave vectors of 91 nm -1 . Observed raw Bragg x-ray integrated intensities cover an extraordinary range, greater than 10 5 , due to the combined effect of the Debye-Waller factor and electronic form factor. From analysis of these intensities mean-square atomic vibration amplitudes Q 2 > and Lindemann ratios are determined. Path-integral Monte Carlo (PIMC) computations of Draeger and Ceperley, extrapolated to the thermodynamic limit, provide excellent agreement with these experimental results. For both present measurements and the PIMC results, one finds both a predominantly Gaussian distribution in Q 2 > and an extraordinarily large Lindemann ratio. In contrast, these directly measured x-ray values are significantly larger than published values inferred from Born-von Karman fitting to phonon dispersion measured by neutron scattering. Mildly anharmonic neon, which is fairly well described by self-consistent phonon theories, is contrasted with present results on fcc 4 He at corresponding densities

  13. Overexpression of the TaSHN1 transcription factor in bread wheat leads to leaf surface modifications, improved drought tolerance and no yield penalty under controlled growth conditions.

    Science.gov (United States)

    Bi, Huihui; Shi, Jianxin; Kovalchuk, Natalia; Luang, Sukanya; Bazanova, Natalia; Chirkova, Larissa; Zhang, Dabing; Shavrukov, Yuri; Stepanenko, Anton; Tricker, Penny; Langridge, Peter; Hrmova, Maria; Lopato, Sergiy; Borisjuk, Nikolai

    2018-05-14

    Transcription factors regulate multiple networks, mediating the responses of organisms to stresses, including drought. Here we investigated the role of the wheat transcription factor TaSHN1 in crop growth and drought tolerance. TaSHN1, isolated from bread wheat, was characterised for molecular interactions and functionality. The overexpression of TaSHN1 in wheat was followed by the evaluation of T 2 and T 3 transgenic lines for drought tolerance, growth and yield components. Leaf surface changes were analysed by light microscopy, SEM, TEM and GC-MS/GC-FID. TaSHN1 behaves as a transcriptional activator in a yeast transactivation assay and binds stress-related DNA cis-elements, determinants of which were revealed using 3D molecular modelling. The overexpression of TaSHN1 in transgenic wheat did not result in a yield penalty under the controlled plant growth conditions of a glasshouse. Transgenic lines had significantly lower stomatal density and leaf water loss, and exhibited improved recovery after severe drought, compared to control plants. The comparative analysis of cuticular waxes revealed an increased accumulation of alkanes in leaves of transgenic lines. Our data demonstrate that TaSHN1 may operate as a positive modulator of drought stress tolerance. Positive attributes could be mediated through an enhanced accumulation of alkanes and reduced stomatal density. This article is protected by copyright. All rights reserved.

  14. Sample dilution and bacterial community composition influence empirical leucine-to-carbon conversion factors in surface waters of the world's oceans.

    Science.gov (United States)

    Teira, Eva; Hernando-Morales, Víctor; Cornejo-Castillo, Francisco M; Alonso-Sáez, Laura; Sarmento, Hugo; Valencia-Vila, Joaquín; Serrano Catalá, Teresa; Hernández-Ruiz, Marta; Varela, Marta M; Ferrera, Isabel; Gutiérrez Morán, Xosé Anxelu; Gasol, Josep M

    2015-12-01

    The transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu(-1) and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  15. Plasma rich in growth factors (PRGF) eye drops stimulates scarless regeneration compared to autologous serum in the ocular surface stromal fibroblasts.

    Science.gov (United States)

    Anitua, E; de la Fuente, M; Muruzabal, F; Riestra, A; Merayo-Lloves, J; Orive, G

    2015-06-01

    Autologous serum (AS) eye drops was the first blood-derived product used for the treatment of corneal pathologies but nowadays PRGF arises as a novel interesting alternative to this type of diseases. The purpose of this study was to evaluate and compare the biological outcomes of autologous serum eye drops or Plasma rich in growth factors (PRGF) eye drops on corneal stromal keratocytes (HK) and conjunctival fibroblasts (HConF). To address this, blood from healthy donors was collected and processed to obtain autologous serum (AS) eye drops and plasma rich in growth factors (PRGF) eye drops. Blood-derivates were aliquoted and stored at -80°C until use. PDGF-AB, VEGF, EGF, FGFb and TGF-β1 were quantified. The potential of PRGF and AS in promoting wound healing was evaluated by means of proliferation and migration assays in HK and HConF. Fibroblast cells were induced to myofibroblast differentiation after treatment with 2.5ng/mL of TGF-β1. The capability of PRGF and AS to prevent and inhibit TGF-β1-induced differentiation was evaluated. Results showed significant higher levels of all growth factors analyzed in PRGF eye drops compared to AS. Moreover, PRGF eye drops enhanced significantly the biological outcomes of both HK and HConF, and reduced TGF-β1-induced myofibroblast differentiation in contrast to autologous serum eye drops (AS). In summary, these results suggest that PRGF exerts enhanced biological outcomes than AS. PRGF may improve the treatment of ocular surface wound healing minimizing the scar formation compared to AS. Results obtained herein suggest that PRGF protects and reverses the myofibroblast phenotype while promotes cell proliferation and migration. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

    KAUST Repository

    Teira, Eva

    2015-09-25

    The transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world\\'s oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu−1 and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean.

  17. Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

    KAUST Repository

    Teira, Eva; Hernando-Morales, Ví ctor; Cornejo-Castillo, Francisco M.; Alonso-Sá ez, Laura; Sarmento, Hugo; Valencia-Vila, Joaquí n; Serrano Catalá , Teresa; Herná ndez-Ruiz, Marta; Varela, Marta M.; Ferrera, Isabel; Moran, Xose Anxelu G.; Gasol, Josep M.

    2015-01-01

    The transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu−1 and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean.

  18. X-ray absorption edges and E.X.A.F.S.: application to the study of electronic and atomic structures of titanium and vanadium carbides TiC(1-x) and VC(1-x)

    International Nuclear Information System (INIS)

    Moisy-Maurice, Virginie.

    1980-09-01

    This text presents a systematic study of the X-ray absorption fine structures evolution, at the K edge of titanium, with vacancy concentration in TiC(1-x). The absorption edges are situated in the 50 eV following the coefficient discontinuity: from the evaluation of their general aspect, it is deduced that the positive charge of titanium atoms decreases when vacancy concentration increases in TiC(1-x). This allowed us to determine the best band structure calculation model. The interpretation of EXAFS spectra (modulation of the absorption coefficient until 1500 eV above the edge) gives indications about the local atomic structure. Here, the contraction of the average titanium-carbon interatomic distances compared to the distances between crystallographic sites is of the order of the experimental resolution 0.02 A for Ti C(0.8). The study of the damping of the spectra in terms of Debye-Waller factors gave an evaluation of the relative static atomic mean square displacements between first neighbours. Last, it has been established that the disordering of vacancies in the order-disorder transition of V 8 C 7 is an atomic scale phenomenon [fr

  19. Paracrystalline structure of activated carbons

    Science.gov (United States)

    Szczygielska, A.; Burian, A.; Dore, J. C.

    2001-06-01

    Structural studies by means of neutron diffraction of activated carbons, prepared from a polymer of phenol formaldehyde resin by carbonization and activation processes, with variable porosity, are presented. The neutron scattering data were recorded over the range of the scattering vector Q from 2.5 to 500 nm-1. The structure of activated carbons has been described in terms of disordered graphite-like layers with very weak interlayer correlations. The model has been generated by computer simulations and its validity has been tested by comparison of the experimental and calculated intensity functions. Modelling studies have shown that the model containing 3-4 layers each about 2 nm in diameter accounts for the experimental data and that graphite layers are randomly translated and rotated, according to the turbostratic structure. Near-neighbour carbon-carbon distances of about 0.139 nm and 0.154 nm have been determined. The Debye-Waller factor exp (-Q2σ2/2) with σ = σ0(r)1/2 suggests a paracrystalline structure within a single layer. The value of the interlayer spacing of 0.36 nm has been found from paracrystalline simulations of the layer arrangement in the c-axis direction. The high quality of the experimental data has enabled determination of the coordination numbers, the interatomic distances and their standard deviations using a curve-fitting procedure over the Q-range from 250 nm to 500 nm, providing structural information about short- and intermediate-range ordering.

  20. Local Structure of Mn in (La1-xHox)2/3Ca1/3MnO3 Studied by X-ray Absorption Fine Structure

    International Nuclear Information System (INIS)

    Pietnoczka, A.; Bacewicz, R.; Antonowicz, J.; Zalewski, W.; Pekala, M.; Drozd, V.; Fagnard, J.F.; Vanderbemden, P.

    2010-01-01

    Results of X-ray absorption fine structure measurements in manganites (La 1-x Ho x ) 2/3 Ca 1/3 MnO 3 with 0.15 3 is doped with a divalent element such as Ca 2+ , substituting for La 3+ , holes are induced in the filled Mn d orbitals. This leads to a strong ferromagnetic coupling between Mn sites. Ca ions in La 1-x Ca x MnO 3 introduce a distortion of the crystal lattice and mixed valence Mn ions (Mn 3+ and Mn 4+ ). On the other hand, in manganites (La 1-x Ho x ) 2/3 Ca 1/3 MnO 3 the substitution of La for Ho causes a lattice distortion and induces a disorder, which reduces a magnetic interaction. The ferromagnetic transition temperature and conductivity decrease very quickly with increasing x. The magnetic and transport properties of compounds depend on the local atomic structure around Mn ions. The information on the bond lengths and Debye-Waller factor are obtained from the extended X-ray absorption fine structure (EXAFS) data analysis. The charge state of Mn is determined from the position of the absorption edge in X-ray absorption near edge structure (XANES) data. XAFS results are in good agreement with magnetic characteristics of the studied materials. (authors)

  1. EXAFS and EPR study of La0.6Sr0.2Ca0.2MnO3 and La0.6Sr0.2Ba0.2MnO3

    International Nuclear Information System (INIS)

    Yang, D.-K.Dong-Seok; Ulyanov, A.N.; Phan, Manh-Huong; Kim, Ikgyun; Ahn, Byong-Keun; Rhee, Jang Roh; Kim, Jung Sun; Nguyen, Chau; Yu, Seong-Cho

    2003-01-01

    Extended X-ray absorption fine structure (EXAFS) analysis and electron-paramagnetic resonance (EPR) have been used to examine the local structure and the internal dynamics of La 0.6 Sr 0.2 Ca 0.2 MnO 3 and La 0.6 Sr 0.2 Ba 0.2 MnO 3 lanthanum manganites. The Mn-O bond distance (∼1.94 Angst for both samples) and the Debye-Waller factors (0.36x10 -2 and 0.41x10 -2 Angst 2 for La 0.6 Sr 0.2 Ca 0.2 MnO 3 and for La 0.6 Sr 0.2 Ba 0.2 MnO 3 , respectively) were obtained from the EXAFS analysis. The dependence of the EPR line width on dopant kind (Ca or Ba) showed a decrease of the spin-lattice interaction with an increase of the Curie temperature. For both compositions, the EPR line intensity followed the exponential law I(T)=I 0 exp(E a /k B T), deduced on the basis of the adiabatic polaron hopping model

  2. Ab initio theory and calculations of X-ray spectra

    International Nuclear Information System (INIS)

    Rehr, J.J.; Kas, J.J.; Prange, M.P.; Sorini, A.P.; Takimoto, Y.; Vila, F.

    2009-01-01

    There has been dramatic progress in recent years both in the calculation and interpretation of various x-ray spectroscopies. However, current theoretical calculations often use a number of simplified models to account for many-body effects, in lieu of first principles calculations. In an effort to overcome these limitations we describe in this article a number of recent advances in theory and in theoretical codes which offer the prospect of parameter free calculations that include the dominant many-body effects. These advances are based on ab initio calculations of the dielectric and vibrational response of a system. Calculations of the dielectric function over a broad spectrum yield system dependent self-energies and mean-free paths, as well as intrinsic losses due to multielectron excitations. Calculations of the dynamical matrix yield vibrational damping in terms of multiple-scattering Debye-Waller factors. Our ab initio methods for determining these many-body effects have led to new, improved, and broadly applicable x-ray and electron spectroscopy codes. (authors)

  3. Extended x-ray absorption fine structure in Ga1-xMnxN/SiC films with high Mn content

    Science.gov (United States)

    Sancho-Juan, O.; Martínez-Criado, O.; Cantarero, A.; Garro, N.; Salomé, M.; Susini, J.; Olguín, D.; Dhar, S.; Ploog, K.

    2011-05-01

    In this study, the local atomic structure of highly homogeneous Ga1-xMnxN alloy films (0.03Debye-Waller factor does not show a significant trend as Mn content increases, which suggests the presence of short-range disorder in the GaN lattice. Ab initio calculations of the structural parameter for two different Mn concentrations are consistent with the experimental results.

  4. Phonon activity and intermediate glassy phase of YVO3

    International Nuclear Information System (INIS)

    Massa, Nestor E.; Piamonteze, Cinthia; Tolentino, Helio C.N.; Alonso, Jose Antonio; Martinez-Lope, Maria Jesus; Casais, Maria Teresa

    2004-01-01

    We show that in YVO 3 additional hard phonons gradually become zone center infrared active below ∼210 K, verifying that a lattice phase transition takes place at about that temperature. Their gradual increment in intensity between ∼210 and ∼77 K is associated with a 'glassy' behavior found in the temperature-dependent V K edge pseudoradial distribution. This translates into an increase in the Debye-Waller factors ascribed to the appearance of V local structural disorder below ∼150 K. Conflicts between various ordering mechanisms in YVO 3 bring up similarities of the intermediate phase to known results in dielectric incommensurate systems, suggesting the formation of commensurate domains below 116 K, the onset temperature of G-type antiferromagnetism. We propose that ∼210 and ∼77 K be understood as the temperatures where the commensurate-incommensurate and incommensurate-commensurate 'lock-in' phase transitions take place. We found support for this interpretation in the inverted λ shapes of the measured heat capacity and in the overall temperature dependence of the hard phonons

  5. Bond length variation in Zn substituted NiO studied from extended X-ray absorption fine structure

    Science.gov (United States)

    Singh, S. D.; Poswal, A. K.; Kamal, C.; Rajput, Parasmani; Chakrabarti, Aparna; Jha, S. N.; Ganguli, Tapas

    2017-06-01

    Bond length behavior for Zn substituted NiO is determined through extended x-ray absorption fine structure (EXAFS) measurements performed at ambient conditions. We report bond length value of 2.11±0.01 Å for Zn-O of rock salt (RS) symmetry, when Zn is doped in RS NiO. Bond length for Zn substituted NiO RS ternary solid solutions shows relaxed behavior for Zn-O bond, while it shows un-relaxed behavior for Ni-O bond. These observations are further supported by first-principles calculations. It is also inferred that Zn sublattice remains nearly unchanged with increase in lattice parameter. On the other hand, Ni sublattice dilates for Zn compositions up to 20% to accommodate increase in the lattice parameter. However, for Zn compositions more than 20%, it does not further dilate. It has been attributed to the large disorder that is incorporated in the system at and beyond 20% of Zn incorporation in the cubic RS lattice of ternary solid solutions. For these large percentages of Zn incorporation, the Ni and the Zn atoms re-arrange themselves microscopically about the same nominal bond length rather than systematically increase in magnitude to minimize the energy of the system. This results in an increase in the Debye-Waller factor with increase in the Zn concentration rather than a systematic increase in the bond lengths.

  6. New determination of the vapour pressures of the isotopes of neon

    International Nuclear Information System (INIS)

    Roth, R.

    1960-03-01

    We have undertaken an experimental reinvestigation of the vapor pressures of the neon isotopes over the temperature range 16.30-30.1 deg. K. Measurements were made by differential manometry in a Giauque-Johnston type cryostat modified for temperature stability. The New sample contained 99.9 % Ne 20 and the Ne 22 sample contained 72,2 % Ne 22 . Extrapolation to pure Ne 20 and Ne 22 can be made with sufficient accuracy by the use of Raoult's law. Our results are in substantial agreement with those of Keesom and Haantjes. At 20 deg. K, where the scatter in our data is an order of magnitude smaller than in the data of Keesom and Haantjes, we find In P Ne 20 /P Ne 22 is 6 % larger than the smoothed line given by them. For solid neon, our data can be represented to a high accuracy by a Debye harmonic lattice with θ D (Ne 20 ) = 74.6 deg. K. The result may be compared with the value obtained by Henshaw from the Debye-Waller temperature factor, θ D = 73 deg. K, and with the recent calculation of the zero point energy of Ne by Bernardes, from which he obtains θ D 8E θ /9R = 73 deg.. K. (author) [fr

  7. Complete Quantum Control of a Single Silicon-Vacancy Center in a Diamond Nanopillar

    Science.gov (United States)

    Zhang, Jingyuan Linda; Lagoudakis, Konstantinos G.; Tzeng, Yan-Kai; Dory, Constantin; Radulaski, Marina; Kelaita, Yousif; Shen, Zhi-Xun; Melosh, Nicholas A.; Chu, Steven; Vuckovic, Jelena

    Coherent quantum control of a quantum bit (qubit) is an important step towards its use in a quantum network. SiV- center in diamond offers excellent physical qualities such as low inhomogeneous broadening, fast photon emission, and a large Debye-Waller factor, while the fast spin manipulation and techniques to extend the spin coherence time are under active investigation. Here, we demonstrate full coherent control over the state of a single SiV- center in a diamond nanopillar using ultrafast optical pulses. The high quality of the chemical vapor deposition grown SiV- centers allows us to coherently manipulate and quasi-resonantly read out the state of the single SiV- center. Moreover, the SiV- centers being coherently controlled are integrated into diamond nanopillar arrays in a site-controlled, individually addressable manner with high yield, low strain, and high spectral stability, which paves the way for scalable on chip optically accessible quantum system in a quantum photonic network. Financial support is provided by the DOE Office of Basic Energy Sciences, Division of Materials Sciences through Stanford Institute for Materials and Energy Sciences (SIMES) under contract DE-AC02-76SF00515.

  8. A low temperature neutron diffraction study of manganese ferrite

    International Nuclear Information System (INIS)

    Jirak, Z.; Zajicek, J.

    1978-01-01

    Two specimens of the Mnsub(0.98)Fesub(2.02)Osub(4+0.002) monocrystal differing in the degree of inversion and heat treatment were studied at room temperature and at the liquid helium temperature, respectively. The specimen with the lower inversion degree was heated to 600 degC and subsequently slowly cooled to 340 degC and annealed for 50 hrs; the specimen with the higher inversion degree was quenched from a temperature of 600 degC. In the study, the magnetic moments on sites A and B of the spinel lattice, the degree of inversion, the oxygen parameter and the Debye-Waller factor were investigated. The oxygen parameter was found to be higher at both temperatures for the annealed specimen (with the lower inversion degree), which can be attributed to the inversion degree dependence of the Madelung energy and the mean ion radius on sites A and B. The oxygen parameter did not show significant differences at room and liquid helium temperature. This agrees with the assumption that it is temperature-independent. (J.P.)

  9. Structural and lattice dynamics studies of microcrystals by means of the Moessbauer effect spectroscopy

    International Nuclear Information System (INIS)

    Pasternak, M.

    1978-05-01

    Moessbauer studies on 129 I, 57 Fe and 119 Sn were conducted in several disordered and microscopic systems in order to investigate properties of lattice dynamics, chemical bonding and phase transitions. The project included the following studies: (1) Granular crystals of Sn embedded in tin-oxide matrix; the nature of the superconductivity transition of very small grains of tin was investigated. (2) Lattice dynamics and characterization of amorphous tin oxide obtained by condensing atoms of Sn and O 2 gas on a 77 K substrate. The hyperfine interaction and the temperature dependence of the Debye-Waller factor were essential to determine the structure of the amorphous tin oxide. (3) The nature of the chemical bond of the alkaly halides ionic crystals and molecules; molecules of Li, Na, K, Rb and Cs iodides were trapped in agron matrices, and the isomer-shift values were obtained from absorption spectra. (4) Binding of single iron and tin atoms to CH 4 , NH 3 , H 2 and C 6 H 6 molecules, with samples at low temperatures between 2 and 77 K; conclusions were derived regarding the cryochemistry of these systems, as related to fundamental problems of catalysis, chemisorption and ''cracking'' of organic molecules

  10. Study of the diffusion movements of water by quasi-elastic scattering of slow neutrons

    International Nuclear Information System (INIS)

    Yamazaki, Ione Makiko

    1980-01-01

    The diffusion movements of water at three different temperatures in the liquid state have been studied by slow neutron quasi-elastic scattering. The measurements have been performed using the IPEN Triple Axis Spectrometer. Broadening and integrated intensity of the quasi-elastic line have been determined for several momentum transfer (K) in the range 0,7627 ≤ K ≤ 2,993 A -1 . The broadening of the quasi-elastic peaks as function of momentum transfer (K) observed at various temperatures has been interpreted in terms of globular diffusion models. The results obtained at 30 deg C have been explained in a consistent way considering the translational and rotational globular diffusion movements. To describe the results obtained at 55 deg and 70 deg C only the translational globular diffusion model was sufficient. This analysis indicates the existence in water of globules with distance of the farest proton position to the center of gravity of the globule 4,5 A, corroborating the idea of quasi-crystalline structure for water. The Debye-Waller factor has been obtained through the analysis of the integrated intensity of quasi-elastic scattering peaks over the K 2 measured range. From this analysis an estimative of the mean square displacement was obtained. (author)

  11. Inelastic scattering in condensed matter with high intensity Mossbauer radiation: Progress report, March 1, 1985-October 31, 1987

    International Nuclear Information System (INIS)

    Yelon, W.B.; Schupp, G.

    1987-10-01

    A facility for high intensity Moessbauer scattering has been commissioned at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue University using special isotopes produced at MURR. A number of scattering studies have been successfully carried out, including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS 2 which indicates phason rather than phonon behavior. High precision, fundamental Moessbauer effect studies have also been carried out using scattering to filter unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape. This method allows complete correction for source resonance self-absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. This analysis is important to both the funadmental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct elastic fractions and lineshape parameters. These advances, coupled to our improvements in MIcrofoil Conversion Electron (MICE) spectroscopy, lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support

  12. Evidence of a splitting of the Mn-O distance and of a large lattice disorder in the charge-ordered phase of LiMn2O4 obtained by EXAFS

    International Nuclear Information System (INIS)

    Paolone, A.; Castellano, C.; Cantelli, R.; Rousse, G.; Masquelier, C.

    2003-01-01

    We measured the extended x-ray-absorption fine-structure (EXAFS) spectrum of LiMn 2 O 4 below room temperature in the charge-ordered phase and for comparison at room temperature in the cubic phase. By means of a standard fit procedure we verified that, as reported by neutron-scattering experiments, also at the local level there are two different Mn-O distances below room temperature, which correspond to the surroundings of well-defined Mn 3+ and Mn 4+ ions. This result is different from the ones obtained from previous EXAFS measurements and confirms the physical picture of the phase transition caused by the ordering of charges in contrast to a cooperative Jahn-Teller phenomenon. Moreover a large lattice disorder in the charge-ordered state, which determines a significant static contribution to the EXAFS Debye-Waller factor, has been found. This last result can be considered as the EXAFS spectral mark of charge-order transitions, even in those materials in which there is no clear evidence of the splitting of bond lengths

  13. Project of integrity assessment of flawed components with structural discontinuity (IAF). Data book for estimation stress intensity factor. Surface crack on ICM housing for penetration in reactor vessel

    International Nuclear Information System (INIS)

    2012-12-01

    The project of Integrity Assessment of Flawed Components with Structural Discontinuity (IAF) was entrusted to Japan Power Engineering and Inspection Corporation (JAPEIC) from Nuclear and Industrial Safety Agency (NISA) and started from FY 2001. And then, it was taken over to Japan Nuclear Energy Safety Organization (JNES) which was established in October 2003 and carried out until FY 2007. In the IAF project, weld joints between nickel based alloys and low alloy steels around penetrations in reactor vessel, safe-end of nozzles and shroud supports were selected from among components and pipe arrangements in nuclear power plants, where high residual stresses were generated due to welding and complex structure. Residual stresses around of the weld joints were estimated by finite element analysis method (FEM) with a general modeling method, then the reasonability and the conservativeness was evaluated. In addition, for postulated surface crack of stress corrosion cracking (SCC), a simple calculation method of stress intensity factor (K) required to estimate the crack growth was proposed and the effectiveness was confirmed. JNES compiled results of the IAF project into Data Books of Residual Stress Analysis of Weld Joint, and Data Book of Simplified Stress Intensity Factor Calculation for Penetration of Reactor as typical Structure Discontinuity, respectively. Data Books of Residual Stress Analysis in Weld Joint. 1. Butt Weld Joint of Small Diameter Cylinder (4B Sch40) (JNES-RE-2012-0005), 2. Dissimilar Metal Weld Joint in Safe End (One-Side Groove Joint (JNES-RE-2012-0006), 3. Dissimilar Metal Weld Joint in Safe End (Large Diameter Both-Side Groove Joint) (JNES-RE-2012-0007), 4. Weld Joint around Penetrations in Reactor Vessel (Insert Joint) (JNES-RE-2012-0008), 5. Weld Joint in Shroud Support (H8, H9, H10 and H11 Welds) (JNES-RE-2012-0009), 6. Analysis Model of Dissimilar Metal Weld Joint Applied Post Weld Heat Treatment (PWHT) (JNES-RE-2012-0010). Data Book of

  14. Factors affecting the fate and transport of glyphosate and AMPA into surface waters of agricultural watersheds in the United States and Europe

    Science.gov (United States)

    Coupe, R.; Kalkhoff, S.; Capel, P.; Gregoire, C.

    2012-04-01

    Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used extensively in almost all agricultural and urban areas of the United States and Europe. Although, glyphosate is used widely throughout the world in the production of many crops, it is predominately used in the United States on soybeans, corn, potatoes, and cotton that have been genetically modified to be tolerant to glyphosate. From 1992 to 2007, the agricultural use of glyphosate has increased from less than 10,000 Mg to more than 80,000 Mg, respectively. The greatest areal use is in the midwestern United States where glyphosate is applied on transgenic corn and soybeans. Because of the difficulty and expense in analyzing for glyphosate and AMPA (aminomethylphosphonic acid, a primary glyphosate degradate) in water, there have been only small scale studies on the fate and transport of glyphosate. The characterization of the transport of glyphosate and AMPA on a watershed scale is lacking. Glyphosate and AMPA were frequently detected in the surface waters of 4 agricultural watersheds in studies conducted by the U.S. Geological Survey in the United States and at the Laboratory of Hydrology and Geochemistry of Strasbourg. Two of these basins were located in the midwestern United States where the major crops are corn and soybean, the third is located the lower Mississippi River Basin where the major crops are soybean, corn, rice, and cotton, and the fourth was located near Strasbourg, France where the use of glyphosate was on a vineyard. The load as a percent of use ranged from 0.009 to 0.86 percent and could be related to 3 factors: source strength, hydrology, and flowpath. Glyphosate use in a watershed results in some occurrence in surface water at the part per billion level; however, those watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff, and a flowpath that does not include transport through the soil.

  15. Surface modification of vascular endothelial growth factor-loaded silk fibroin to improve biological performance of ultra-high-molecular-weight polyethylene via promoting angiogenesis

    Directory of Open Access Journals (Sweden)

    Ai C

    2017-10-01

    Full Text Available Chengchong Ai, Dandan Sheng, Jun Chen, Jiangyu Cai, Siheng Wang, Jia Jiang, Shiyi Chen Department of Sports Medicine, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China Abstract: Ultra-high-molecular-weight polyethylene (UHMWPE has been applied in orthopedics, as the materials of joint prosthesis, artificial ligaments, and sutures due to its advantages such as high tensile strength, good wear resistance, and chemical stability. However, postoperative osteolysis induced by UHMWPE wear particles and poor bone–implant healing interface due to scarcity of osseointegration is a significant problem and should be solved imperatively. In order to enhance its affinity to bone tissue, vascular endothelial growth factor (VEGF was loaded on the surface of materials, the loading was performed by silk fibroin (SF coating to achieve a controlled-release delivery. Several techniques including field emission scanning electron microscopy (FESEM and attenuated total reflectance (ATR-Fourier transform infrared (FTIR and water contact angle measurement were used to validate the effectiveness of introduction of SF/VEGF. The result of ELISA demonstrated that the release of VEGF was well maintained up to 4 weeks. The modified UHMWPE was evaluated by both in vitro and in vivo experiments. According to the results of FESEM and cell counting kit-8 (CCK-8 assay, bone marrow mesenchymal stem cells cultured on the UHMWPE coated with SF/VEGF and SF exhibited a better proliferation performance than that of the pristine UHMWPE. The model rabbit of anterior cruciate ligament reconstruction was used to observe the graft–bone healing process in vivo. The results of histological evaluation, microcomputed tomography (micro-CT analysis, and biomechanical tests performed at 6 and 12 weeks after surgery demonstrated that graft–bone healing could be significantly improved due to the effect of VEGF on angiogenesis, which was loaded on the surface by SF

  16. Surface Water & Surface Drainage

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data set contains boundaries for all surface water and surface drainage for the state of New Mexico. It is in a vector digital data structure digitized from a...

  17. Lessons from the Crystal Structure of the S. aureus Surface Protein Clumping Factor A in Complex With Tefibazumab, an Inhibiting Monoclonal Antibody

    Directory of Open Access Journals (Sweden)

    Vannakambadi K. Ganesh

    2016-11-01

    Full Text Available The Staphylococcus aureus fibrinogen binding MSCRAMM (Microbial Surface Components Recognizing Adhesive Matrix Molecules, ClfA (clumping factor A is an important virulence factor in staphylococcal infections and a component of several vaccines currently under clinical evaluation. The mouse monoclonal antibody aurexis (also called 12-9, and the humanized version tefibazumab are therapeutic monoclonal antibodies targeting ClfA that in combination with conventional antibiotics were effective in animal models but showed less impressive efficacy in a limited Phase II clinical trial. We here report the crystal structure and a biochemical characterization of the ClfA/tefibazumab (Fab complex. The epitope for tefibazumab is located to the “top” of the N3 subdomain of ClfA and partially overlaps with a previously unidentified second binding site for fibrinogen. A high-affinity binding of ClfA to fibrinogen involves both an interaction at the N3 site and the previously identified docking of the C-terminal segment of the fibrinogen γ-chain in the N2N3 trench. Although tefibazumab binds ClfA with high affinity we observe a modest IC50 value for the inhibition of fibrinogen binding to the MSCRAMM. This observation, paired with a common natural occurring variant of ClfA that is not effectively recognized by the mAb, may partly explain the modest effect tefibazumab showed in the initial clinic trail. This information will provide guidance for the design of the next generation of therapeutic anti-staphylococcal mAbs targeting ClfA.

  18. Roles of a novel Crp/Fnr family transcription factor Lmo0753 in soil survival, biofilm production and surface attachment to fresh produce of Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    Joelle K Salazar

    Full Text Available Listeria monocytogenes is a foodborne bacterial pathogen and the causative agent of an infectious disease, listeriosis. L. monocytogenes is ubiquitous in nature and has the ability to persist in food processing environments for extended periods of time by forming biofilms and resisting industrial sanitization. Human listeriosis outbreaks are commonly linked to contaminated dairy products, ready-to-eat meats, and in recent years, fresh produce such as lettuce and cantaloupes. We identified a putative Crp/Fnr family transcription factor Lmo0753 that is highly specific to human-associated genetic lineages of L. monocytogenes. Lmo0753 possesses two conserved functional domains similar to the major virulence regulator PrfA in L. monocytogenes. To determine if Lmo0753 is involved in environmental persistence-related mechanisms, we compared lmo0753 deletion mutants with respective wild type and complementation mutants of two fully sequenced L. monocytogenes genetic lineage II strains 10403S and EGDe for the relative ability of growth under different nutrient availability and temperatures, soil survival, biofilm productivity and attachment to select fresh produce surfaces including romaine lettuce leaves and cantaloupe rinds. Our results collectively suggested that Lmo0753 plays an important role in L. monocytogenes biofilm production and attachment to fresh produce, which may contribute to the environmental persistence and recent emergence of this pathogen in human listeriosis outbreaks linked to fresh produce.

  19. One-pot preparation of conducting composite containing abundant amino groups on electrode surface for electrochemical detection of von willebrand factor

    Science.gov (United States)

    Wang, Wen; Ma, Chao; Li, Yi; Liu, Baihui; Tan, Liang

    2018-03-01

    A one-pot protocol based on cyclic voltammetric scan was employed to prepare new conducting composite that was abundant in amino groups. The scanning electron microscope, atomic force microscope, X-ray photoelectron spectroscopy and infrared spectrum characterization demonstrate that poly(azure A), gold nanoparticles, chitosan and cysteine were immobilized simultaneously on glassy carbon electrode surface. Von Willebrand factor (vWF) antibody (Ab) was subsequently assembled by using glutaraldehyde to construct the Ab/composite-modified electrode. The capture of vWF could inhibit the charge transfer between the ferri-/ferrocyanide probe and the electrode and exert the negative effect on the electrochemical response of the dye polymer in the conducting composite due to the strong steric hindrance effect. The DPV peak current change before and after the immunoreaction was found to be proportional to the logarithm of the vWF concentration from 0.001 to 100 μg mL-1 with a detection limit of 0.4 ng mL-1. The proposed label-free electrochemical method was employed in the investigation on the release of vWF by oxidation-injured vascular endothelial cells. The experimental results exhibit that the vWF content in growth medium was increased when the oxidation injury of the cells was intensified in the presence of H2O2.

  20. Measuring the surface-enhanced Raman scattering enhancement factors of hot spots formed between an individual Ag nanowire and a single Ag nanocube

    International Nuclear Information System (INIS)

    Camargo, Pedro H C; Cobley, Claire M; Rycenga, Matthew; Xia Younan

    2009-01-01

    This paper describes a systematic study of the surface-enhanced Raman scattering (SERS) activity of hot spots formed between a Ag nanowire and a Ag nanocube with sharp corners. We investigated two distinct dimer structures: (i) a nanocube having one side face nearly touching the side face of a nanowire, and (ii) a nanocube having one edge nearly touching the side face of a nanowire. The field enhancements for the dimers displayed a strong dependence on laser polarization, and the strongest SERS intensities were observed for polarization along the hot-spot axis. Moreover, the detected SERS intensities were dependent on the hot-spot structure, i.e., the relative orientation of the Ag nanocube with respect to the nanowire's side face. When the dimer had a face-to-face configuration, the enhancement factor EF dimer was 1.4 x 10 7 . This corresponds to 22-fold and 24-fold increases compared to those for individual Ag nanowires and nanocubes, respectively. Conversely, when the dimer had an edge-to-face configuration, EF dimer was 4.3 x 10 6 . These results demonstrated that the number of probe molecules adsorbed at the hot spot played an important role in determining the detected SERS intensities. EF dimer was maximized when the dimer configuration allowed for a larger number of probe molecules to be trapped within the hot-spot region.

  1. The major surface glycoprotein of Pneumocystis carinii induces release and gene expression of interleukin-8 and tumor necrosis factor alpha in monocytes

    DEFF Research Database (Denmark)

    Benfield, T L; Lundgren, Bettina; Levine, S J

    1997-01-01

    Recent studies suggest that interleukin-8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) may play a central role in host defense and pathogenesis during Pneumocystis carinii pneumonia. In order to investigate whether the major surface antigen (MSG) of human P. carinii is capable of eliciting...... the release of IL-8 and TNF-alpha, human monocytes were cultured in the presence of purified MSG. MSG-stimulated cells released significant amounts of IL-8 within 4 h, and at 20 h, cells stimulated with MSG released 45.5 +/- 9.3 ng of IL-8/ml versus 3.7 +/- 1.1 ng/ml for control cultures (P = 0.......01). In a similar fashion, MSG elicited release of TNF-alpha. Initial increases were also seen at 4 h, and at 20 h, TNF-alpha levels reached 6.4 +/- 1.1 ng/ml, compared to 0.08 +/- 0.01 ng/ml for control cultures (P alpha secretion was observed at 20 h...

  2. Risk Factors and Predictors of Significant Chondral Surface Change From Primary to Revision Anterior Cruciate Ligament Reconstruction: A MOON and MARS Cohort Study.

    Science.gov (United States)

    Magnussen, Robert A; Borchers, James R; Pedroza, Angela D; Huston, Laura J; Haas, Amanda K; Spindler, Kurt P; Wright, Rick W; Kaeding, Christopher C; Allen, Christina R; Anderson, Allen F; Cooper, Daniel E; DeBerardino, Thomas M; Dunn, Warren R; Lantz, Brett A; Mann, Barton; Stuart, Michael J; Albright, John P; Amendola, Annunziato; Andrish, Jack T; Annunziata, Christopher C; Arciero, Robert A; Bach, Bernard R; Baker, Champ L; Bartolozzi, Arthur R; Baumgarten, Keith M; Bechler, Jeffery R; Berg, Jeffrey H; Bernas, Geoffrey A; Brockmeier, Stephen F; Brophy, Robert H; Bush-Joseph, Charles A; Butler, J Brad; Campbell, John D; Carey, James L; Carpenter, James E; Cole, Brian J; Cooper, Jonathan M; Cox, Charles L; Creighton, R Alexander; Dahm, Diane L; David, Tal S; Flanigan, David C; Frederick, Robert W; Ganley, Theodore J; Garofoli, Elizabeth A; Gatt, Charles J; Gecha, Steven R; Giffin, James Robert; Hame, Sharon L; Hannafin, Jo A; Harner, Christopher D; Harris, Norman Lindsay; Hechtman, Keith S; Hershman, Elliott B; Hoellrich, Rudolf G; Hosea, Timothy M; Johnson, David C; Johnson, Timothy S; Jones, Morgan H; Kamath, Ganesh V; Klootwyk, Thomas E; Levy, Bruce A; Ma, C Benjamin; Maiers, G Peter; Marx, Robert G; Matava, Matthew J; Mathien, Gregory M; McAllister, David R; McCarty, Eric C; McCormack, Robert G; Miller, Bruce S; Nissen, Carl W; O'Neill, Daniel F; Owens, Brett D; Parker, Richard D; Purnell, Mark L; Ramappa, Arun J; Rauh, Michael A; Rettig, Arthur C; Sekiya, Jon K; Shea, Kevin G; Sherman, Orrin H; Slauterbeck, James R; Smith, Matthew V; Spang, Jeffrey T; Svoboda, Steven J; Taft, Timothy N; Tenuta, Joachim J; Tingstad, Edwin M; Vidal, Armando F; Viskontas, Darius G; White, Richard A; Williams, James S; Wolcott, Michelle L; Wolf, Brian R; York, James J

    2018-03-01

    Articular cartilage health is an important issue following anterior cruciate ligament (ACL) injury and primary ACL reconstruction. Factors present at the time of primary ACL reconstruction may influence the subsequent progression of articular cartilage damage. Larger meniscus resection at primary ACL reconstruction, increased patient age, and increased body mass index (BMI) are associated with increased odds of worsened articular cartilage damage at the time of revision ACL reconstruction. Case-control study; Level of evidence, 3. Subjects who had primary and revision data in the databases of the Multicenter Orthopaedics Outcomes Network (MOON) and Multicenter ACL Revision Study (MARS) were included. Reviewed data included chondral surface status at the time of primary and revision surgery, meniscus status at the time of primary reconstruction, primary reconstruction graft type, time from primary to revision ACL surgery, as well as demographics and Marx activity score at the time of revision. Significant progression of articular cartilage damage was defined in each compartment according to progression on the modified Outerbridge scale (increase ≥1 grade) or >25% enlargement in any area of damage. Logistic regression identified predictors of significant chondral surface change in each compartment from primary to revision surgery. A total of 134 patients were included, with a median age of 19.5 years at revision surgery. Progression of articular cartilage damage was noted in 34 patients (25.4%) in the lateral compartment, 32 (23.9%) in the medial compartment, and 31 (23.1%) in the patellofemoral compartment. For the lateral compartment, patients who had >33% of the lateral meniscus excised at primary reconstruction had 16.9-times greater odds of progression of articular cartilage injury than those with an intact lateral meniscus ( P < .001). For the medial compartment, patients who had <33% of the medial meniscus excised at the time of the primary reconstruction

  3. Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China - Part 2: The roles of anthropogenic emissions and climate variability

    Science.gov (United States)

    Xu, Wanyun; Xu, Xiaobin; Lin, Meiyun; Lin, Weili; Tarasick, David; Tang, Jie; Ma, Jianzhong; Zheng, Xiangdong

    2018-01-01

    despite ozone increases in eastern China. Analysis of the Trajectory-mapped Ozonesonde data set for the Stratosphere and Troposphere (TOST) and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the quasi-biennial oscillation (QBO), the East Asian summer monsoon (EASM), and the sunspot cycle. Our results suggest that the 2-3-, 3-7-, and 11-year periodicities are linked to the QBO, EASM index, and sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

  4. The meningococcal vaccine candidate neisserial surface protein A (NspA binds to factor H and enhances meningococcal resistance to complement.

    Directory of Open Access Journals (Sweden)

    Lisa A Lewis

    2010-07-01

    Full Text Available Complement forms an important arm of innate immunity against invasive meningococcal infections. Binding of the alternative complement pathway inhibitor factor H (fH to fH-binding protein (fHbp is one mechanism meningococci employ to limit complement activation on the bacterial surface. fHbp is a leading vaccine candidate against group B Neisseria meningitidis. Novel mechanisms that meningococci employ to bind fH could undermine the efficacy of fHbp-based vaccines. We observed that fHbp deletion mutants of some meningococcal strains showed residual fH binding suggesting the presence of a second receptor for fH. Ligand overlay immunoblotting using membrane fractions from one such strain showed that fH bound to a approximately 17 kD protein, identified by MALDI-TOF analysis as Neisserial surface protein A (NspA, a meningococcal vaccine candidate whose function has not been defined. Deleting nspA, in the background of fHbp deletion mutants, abrogated fH binding and mAbs against NspA blocked fH binding, confirming NspA as a fH binding molecule on intact bacteria. NspA expression levels vary among strains and expression correlated with the level of fH binding; over-expressing NspA enhanced fH binding to bacteria. Progressive truncation of the heptose (Hep I chain of lipooligosaccharide (LOS, or sialylation of lacto-N-neotetraose LOS both increased fH binding to NspA-expressing meningococci, while expression of capsule reduced fH binding to the strains tested. Similar to fHbp, binding of NspA to fH was human-specific and occurred through fH domains 6-7. Consistent with its ability to bind fH, deleting NspA increased C3 deposition and resulted in increased complement-dependent killing. Collectively, these data identify a key complement evasion mechanism with important implications for ongoing efforts to develop meningococcal vaccines that employ fHbp as one of its components.

  5. Optimization of Factors Affecting Beauveria bassiana Fungus Ability in Control of Greater Wax Moth (Galleria mellonella L. by Response Surface Method

    Directory of Open Access Journals (Sweden)

    Ali Heidari

    2017-03-01

    bioassay was performed by determining the lethal concentrations of the B.bassiana that cause 20% to 80% casualties with a lot of concentration by immersion method for 10 seconds. Concentrations 1×106 and 1×108 conidia/ml were identified as high and low lethality ranges, respectively. In this study, the central composite design and response surface methodology with three independent variables including temperature (25-35°C, humidity (70-80 percent and concentration (1×106-1×108 conidia/ml and six replications in the central point of the design (to calculate the repeatability of the process were used to evaluate the increase in mortality. The number of experiments was twenty and the dependent variable (response was the mortality of the fifth instar larvae of greater wax moth. For each experiment, 10 last instar larvae were randomly selected and then 10 sterile petri dishes containing sterile wax to feed insect were prepared. Larvae were immersed for 10 seconds in a solution containing the fungus and then were placed in containers. Results and Discussion: Analysis of variance (ANOVA for the quadratic response surface model to factor mortality of the fifth instar larvae of greater wax moth showed that quadratic model is statistically significant (P≤0.001. Also high R2 (R2 = 0.9430 and coordination of adjusted R2 (Adj R2 = 0.9211 indicates the strength of the model to predict. According to tests, the optimal conditions for achieving maximum mortality of the fifth instar larvae of greater wax moth is 25 ° C temperature, 75% humidity and 1×108 conidia/ml concentration, respectively. Settings applied to the optimization process, was including maximum mortality. The effect of temperature on mortality of the fifth instar larvae of this insect showed that the mortality rate decreased with increasing temperature. Cause of mortality reduction as increasing the temperature is probably related to the characteristics of this fungus that could be affected by temperature, so that

  6. The 1.7 Å X-ray crystal structure of the porcine factor VIII C2 domain and binding analysis to anti-human C2 domain antibodies and phospholipid surfaces.

    Directory of Open Access Journals (Sweden)

    Caileen M Brison

    Full Text Available The factor VIII C2 domain is essential for binding to activated platelet surfaces as well as the cofactor activity of factor VIII in blood coagulation. Inhibitory antibodies against the C2 domain commonly develop following factor VIII replacement therapy for hemophilia A patients, or they may spontaneously arise in cases of acquired hemophilia. Porcine factor VIII is an effective therapeutic for hemophilia patients with inhibitor due to its low cross-reactivity; however, the molecular basis for this behavior is poorly understood. In this study, the X-ray crystal structure of the porcine factor VIII C2 domain was determined, and superposition of the human and porcine C2 domains demonstrates that most surface-exposed differences cluster on the face harboring the "non-classical" antibody epitopes. Furthermore, antibody-binding results illustrate that the "classical" 3E6 antibody can bind both the human and porcine C2 domains, although the inhibitory titer to human factor VIII is 41 Bethesda Units (BU/mg IgG versus 0.8 BU/mg IgG to porcine factor VIII, while the non-classical G99 antibody does not bind to the porcine C2 domain nor inhibit porcine factor VIII activity. Further structural analysis of differences between the electrostatic surface potentials suggest that the C2 domain binds to the negatively charged phospholipid surfaces of activated platelets primarily through the 3E6 epitope region. In contrast, the G99 face, which contains residue 2227, should be distal to the membrane surface. Phospholipid binding assays indicate that both porcine and human factor VIII C2 domains bind with comparable affinities, and the human K2227A and K2227E mutants bind to phospholipid surfaces with similar affinities as well. Lastly, the G99 IgG bound to PS-immobilized factor VIII C2 domain with an apparent dissociation constant of 15.5 nM, whereas 3E6 antibody binding to PS-bound C2 domain was not observed.

  7. Matrix metalloproteinase 9 (MMP-9) mediated release of MMP-9 resistant stromal cell-derived factor 1α (SDF-1α) from surface modified polymer films.

    Science.gov (United States)

    Steinhagen, Max; Hoffmeister, Peter-Georg; Nordsieck, Karoline; Hötzel, Rudi; Baumann, Lars; Hacker, Michael C; Schulz-Siegmund, Michaela; Beck-Sickinger, Annette G

    2014-04-23

    Preparation of smart materials by coatings of established surfaces with biomolecules will lead to the next generation of functionalized biomaterials. Rejection of implants is still a major problem in medical applications but masking the implant material with protein coatings is a promising approach. These layers not only disguise the material but also equip it with a certain biological function. The anti-inflammatory chemokine stromal cell-derived factor 1α (SDF-1α) is well suited to take over this function, because it efficiently attracts stem cells and promotes their differentiation and proliferation. At least the initial stem cell homing requires the formation of a concentration gradient. Thus, a reliable and robust release mechanism of SDF-1α from the material is essential. Several proteases, most notably matrix metalloproteinases, are upregulated during inflammation, which, in principle, can be exploited for a tightly controlled release of SDF-1α. Herein, we present the covalent immobilization of M-[S4V]-SDF-1α on novel biodegradable polymer films, which consist of heterobifunctional poly(ethylene glycol) and oligolactide-based functionalized macromers. A peptidic linker with a trimeric matrix metalloproteinase 9 (MMP-9) cleavage site (MCS) was used as connection and the linkage between the three components was achieved by combination of expressed protein ligation and Cu(I) catalyzed azide/alkyne cycloaddition. The MCS was used for MMP-9 mediated release of M-[S4V]-SDF-1α from the biomaterial and the released SDF-1α derivative was biologically active and induced strong cell migration, which demonstrates the great potential of this system.

  8. Hospital readmission rates and risk factors for readmission following cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal surface malignancies.

    Science.gov (United States)

    Dreznik, Yael; Hoffman, Aviad; Hamburger, Tamar; Ben-Yaacov, Almog; Dux, Yossi; Jacoby, Harel; Berger, Yaniv; Nissan, Aviram; Gutman, Mordechai

    2018-02-08

    Cytoreductive surgery and Hyperthermic intra-peritoneal chemotherapy (CRS/HIPEC) for peritoneal surface malignancies is associated with high morbidity. The increased numbers of patients undergoing CRS/HIPEC in recent years mandates risk analysis and quality assurance. However, only scarce data exist regarding causative parameters for readmission. The aim of this study was to assess readmission rates and risk factors associated with readmission. A retrospective-cohort study including patients from two high-volume centers who underwent CRS/HIPEC surgery between the years 2007-2016 was performed. Patients' demographics, peri-operative data and readmission rates were recorded. 223 patients were included in the study. The 7 and 30-day readmission rates were 3.5% (n = 8) and 11% (n = 25), respectively. Late readmission rates (up to 90 days) were 11% (n = 25). The most common causes of readmission were surgical related infections (35%), small bowel obstruction (17.5%) and dehydration (14%). Post-operative complications were associated with higher readmission rates (p = 0.0001). PCI score was not associated with higher rates of readmission. Readmissions following CRS/HIPEC occur mainly due to infectious complications and dehydrations. Patients following CRS/HIPEC should be discharged after careful investigation to a community based continuing care with access for IV fluid replacement or antibiotics administration when required. Copyright © 2018 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.

  9. Partial characterization of the cross-reacting determinant, a carbohydrate epitope shared by decay accelerating factor and the variant surface glycoprotein of the African Trypanosoma brucei.

    Science.gov (United States)

    Shak, S; Davitz, M A; Wolinsky, M L; Nussenzweig, V; Turner, M J; Gurnett, A

    1988-03-15

    The variant surface glycoprotein (VSG) of the African trypanosome is anchored in the cell membrane by a complex glycan attached to phosphatidylinositol. The carboxyl terminal portion of VSG contains a cryptic carbohydrate epitope, the cross-reacting determinant (CRD), that is revealed only after removal of the diacylglycerol by phosphatidylinositol-specific phospholipase C (PIPLC) or VSG lipase. Recently, we have shown that after hydrolysis by PIPLC, decay-accelerating factor (DAF)--a mammalian phosphatidylinositol-anchored protein--also contains the CRD epitope. Using a two site immunoradiometric assay in which the capturing antibody is a monoclonal antibody to DAF and the revealing antibody is anti-CRD, we now show that sugar phosphates significantly inhibited the binding of anti-CRD antibody to DAF released by PIPLC. DL-myo-inositol 1,2-cyclic phosphate was the most potent inhibitor of binding (IC50 less than 10(-8) M). Other sugar phosphates, such as alpha-D-glucose-1-phosphate, which also possess adjacent hydroxyl and phosphate moieties in cis also inhibited binding at low concentrations (IC50 = 10(-5) to 10(-4) M). In contrast, sugar phosphates which do not possess adjacent hydroxyl and phosphate moieties in cis and simple sugars weakly inhibited binding (IC50 greater than 10(-3) M). These results suggest that myo-inositol 1,2-cyclic phosphate contributes significantly to the epitope recognized by the anti-CRD antibody and is consistent with analysis of the carboxyl terminus of VSG, which also suggested the presence of the cyclic inositol phosphate. In light of the recent findings that human serum contains a glycan-phosphatidyl-inositol-specific phospholipase D, which converts DAF from a hydrophobic to a hydrophilic form lacking the CRD, the observation that the phosphate is crucial for expression of the epitope may be relevant in understanding the origin of CRD-negative DAF in urine and plasma.

  10. Suburban Soils: Are they the answer in determining factors controlling non-point-source DOC and DON in urban surface waters?

    Science.gov (United States)

    Aitkenhead-Peterson, J. A.

    2016-12-01

    Generally the quality of urban streams has been attributed to storm water runoff and sewage effluent discharge. Recent work in the upper Trinity Basin downstream from the Dallas/Fort Worth metropolis, TX concluded that sewage effluent only contributed between 1 and 35% of DOC dependent upon the population of the watershed. Change from native to urban land use increased DOC exports to between 938 - 1840 kg km-2 yr-1relative to the 517 kg km-2 yr-1 expected from native land use. Where this excess DOC might come from in an urban ecosystem was addressed in a separate study examining water extractable DOC (WEDOC) and DON (WEDON) in soils of single-family home lawns in Chicago, IL, Frederick, MD, Bryan/College Station, TX and Galveston, TX. These cities were exposed to different sources of sodium. Time of exposure to sodium was considered on the assumption that as new sub-divisions are built, new soil or turfgrass sod is introduced to the site. Exposure times were 0-5, 6-10, 11-20, 21-30 and > 30 yr. Length of exposure time of the soil to the urban environment was significant among the four cities examined for DOC (p < 0.001), DON (p < 0.001), sodium adsorption ratio (p < 0.006) but not for sodium (p = 0.08) or exchangeable sodium percent (ESP) (p = 0.09). In all cities WEDON increased with urban exposure time and in all cities except Galveston WEDOC increased with urban exposure time. Sodium, regardless of its source, explained 60% of the variance in WEDOC and 54% of the variance in WEDON across all cities (n = 136). To determine what other factors might be involved in increasing WEDOC and WEDON losses from suburban soils, backward stepwise regression models were used. Across the four cities, time of urban exposure, soil saturated hydraulic conductivity (Ksat), NO3-N, NH4-N, S, PO4-P, Na, Cu, Ca, Fe and Zn produced a significant model for WEDOC (Adjusted r2 = 0.85; p < 0.001) and Ksat, pH, NH4-N, PO4-P, S, Alkalinity and Cu produced a significant model for WEDON

  11. Factors of influence upon the SF-36-based health related quality of life of patients following surgery for petroclival and lateral posterior surface of pyramid meningiomas.

    Science.gov (United States)

    Pintea, B; Kandenwein, J A; Lorenzen, H; Boström, J P; Daher, F; Velazquez, V; Kristof, R A

    2018-03-01

    To describe the patient's self assessed health related quality of life (saHRQoL) based upon the medical outcome study 36-item short form health survey (SF-36) as well as the factors of influence upon the saHRQoL following surgery for petroclival (PCM) and lateral posterior surface of the pyramid (LPPM) meningiomas. In a series of 78 patients operated consecutively for PCM (n = 46) or LPPM (n = 32) the preoperative, intraoperative and postoperative data were collected retrospectively. The saHRQoL was obtained by mailing the SF-36 questionnaire to the patients. The SF-36 data of the whole patients group was compared with a healthy population. The SF-36 data of the PCM- and LPPM were compared to each other. The influence of pre-, intra- and postoperative findings upon the SF-36 was assessed by uni- and multifactorial analysis. 58 (69%) out of the 78 patients answered the SF-36 questionnaire at a median postoperative follow-up of 59 months. The patients, who answered the SF-36 questionnaire, had a significant lower perioperative complication rate than those who did not (46% vs. 75%, p = 0.019). The saHRQoL of the LPPM and PCM was reduced on several sub-scales, when compared to the German reference population. The outcome of PCM is, assessed by saHRQoL as well as by conventional neurosurgical grading scales, inferior to that of LPPM. The saHRQoL of LPPM correlated in the uni- and multivariate analysis with the early postoperative KPI on the sub-scales SF1 (physical functioning) and SF5 (vitality). Accordingly, the sub-scale SF2 (role-physical) of PCM correlated with the change of the KPI from preoperative to the last follow up. The saHRQoL of the evaluable patients was lower than that of the normal population. The saHRQoL score of PCM-patients was lower than that of LPPM-patients. For the future the saHRQol should be assessed routinely; It reflects the patients' perspective upon postoperative outcome and enables the comparison with other treatment modalities

  12. Additively manufactured 3D porous Ti-6Al-4V constructs mimic trabecular bone structure and regulate osteoblast proliferation, differentiation and local factor production in a porosity and surface roughness dependent manner

    International Nuclear Information System (INIS)

    Cheng, Alice; Boyan, Barbara D; Humayun, Aiza; Cohen, David J; Schwartz, Zvi

    2014-01-01

    Additive manufacturing by laser sintering is able to produce high resolution metal constructs for orthopedic and dental implants. In this study, we used a human trabecular bone template to design and manufacture Ti-6Al-4V constructs with varying porosity via laser sintering. Characterization of constructs revealed interconnected porosities ranging from 15–70% with compressive moduli of 2579–3693 MPa. These constructs with macro porosity were further surface-treated to create a desirable multi-scale micro-/nano-roughness, which has been shown to enhance the osseointegration process. Osteoblasts (MG63 cells) exhibited high viability when grown on the constructs. Proliferation (DNA) and alkaline phosphatase specific activity, an early differentiation marker, decreased as porosity increased, while osteocalcin, a late differentiation marker, as well as osteoprotegerin, vascular endothelial growth factor and bone morphogenetic proteins 2 and 4 increased with increasing porosity. Three-dimensional (3D) constructs with the highest porosity and surface modification supported the greatest osteoblast differentiation and local factor production. These results indicate that additively manufactured 3D porous constructs mimicking human trabecular bone and produced with additional surface treatment can be customized for increased osteoblast response. Increased factors for osteoblast maturation and differentiation on high porosity constructs suggest the enhanced performance of these surfaces for increasing osseointegration in vivo. (paper)

  13. Additively manufactured 3D porous Ti-6Al-4V constructs mimic trabecular bone structure and regulate osteoblast proliferation, differentiation and local factor production in a porosity and surface roughness dependent manner.

    Science.gov (United States)

    Cheng, Alice; Humayun, Aiza; Cohen, David J; Boyan, Barbara D; Schwartz, Zvi

    2014-10-07

    Additive manufacturing by laser sintering is able to produce high resolution metal constructs for orthopedic and dental implants. In this study, we used a human trabecular bone template to design and manufacture Ti-6Al-4V constructs with varying porosity via laser sintering. Characterization of constructs revealed interconnected porosities ranging from 15-70% with compressive moduli of 2579-3693 MPa. These constructs with macro porosity were further surface-treated to create a desirable multi-scale micro-/nano-roughness, which has been shown to enhance the osseointegration process. Osteoblasts (MG63 cells) exhibited high viability when grown on the constructs. Proliferation (DNA) and alkaline phosphatase specific activity, an early differentiation marker, decreased as porosity increased, while osteocalcin, a late differentiation marker, as well as osteoprotegerin, vascular endothelial growth factor and bone morphogenetic proteins 2 and 4 increased with increasing porosity. Three-dimensional (3D) constructs with the highest porosity and surface modification supported the greatest osteoblast differentiation and local factor production. These results indicate that additively manufactured 3D porous constructs mimicking human trabecular bone and produced with additional surface treatment can be customized for increased osteoblast response. Increased factors for osteoblast maturation and differentiation on high porosity constructs suggest the enhanced performance of these surfaces for increasing osseointegration in vivo.

  14. Preparation and Evaluation of Dexamethasone (DEX/Growth and Differentiation Factor-5 (GDF-5 Surface-Modified Titanium Using β-Cyclodextrin-Conjugated Heparin (CD-Hep for Enhanced Osteogenic Activity In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Dae Hyeok Yang

    2017-08-01

    Full Text Available The most ideal implant models in the dental and orthopedic fields to minimize the failure rate of implantation involve the improvement of osseointegration with host bone. Therefore, a focus of this study is the preparation of surface-modified titanium (Ti samples of disc and screw types using dexamethasone (DEX and/or growth and differentiation factor-5 (GDF-5, as well as the evaluation of their efficacies on bone formation in vitro and in vivo. X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM and contact angle measurement were used to evaluate the surface chemical composition, surface morphology and wettability, respectively. The results showed that implant surfaces were successfully modified with DEX and/or GDF-5, and had rough surfaces along with hydrophilicity. DEX, GDF-5 or DEX/GDF-5 on the surface-modified samples were rapidly released within one day and released for 28 days in a sustained manner. The proliferation and bone formation of MC3T3-E1 cells cultured on pristine and surface-modified implants in vitro were examined by cell counting kit-8 (CCK-8 assay, as well as the measurements of alkaline phosphatase (ALP activity and calcium deposition, respectively. MC3T3-E1 cells cultured on DEX/GDF-5–Ti showed noticeable ALP activity and calcium deposition in vitro. Active bone formation and strong osseointegration occurred at the interface between DEX/GDF-5–Ti and host bone, as evaluated by micro computed-tomography (micro CT analysis. Surface modification using DEX/GDF-5 could be a good method for advanced implants for orthopaedic and dental applications.

  15. Insights into factors contributing to the observability of a submarine at periscope depth by modern radar, Part 2: EM simulation of mast RCS in a realistic sea surface environment

    CSIR Research Space (South Africa)

    Smit, JC

    2012-09-01

    Full Text Available IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), Cape Town 2-7 September 2012 Insights into factors contributing to the observability of a submarine at periscope depth by modern radar, Part 2: EM... simulation of mast RCS in a realistic sea surface environment Smit JC; Cilliers JE CSIR, Defence, Peace, Safety and Security. PO Box 395, Pretoria, 0001 Abstract Recently, a set of high resolution radar measurements were undertaken in South...

  16. Response surface model for the reduction of Salmonella biofilm on stainless steel with lactic acid, ethanol and chlorine as controlling factors

    Science.gov (United States)

    Bacterial colonization and biofilm formation on food contact surfaces can be sources of contamination of processed foods and poses a serious threat to health. Since chlorine- or ethanol-based disinfection is commonly used in the food industry and kitchens, a disinfectant containing chlorine (Cl), et...

  17. Soil-soil solution distribution coefficient of soil organic matter is a key factor for that of radioiodide in surface and subsurface soils.

    Science.gov (United States)

    Unno, Yusuke; Tsukada, Hirofumi; Takeda, Akira; Takaku, Yuichi; Hisamatsu, Shun'ichi

    2017-04-01

    We investigated the vertical distribution of the soil-soil-solution distribution coefficients (K d ) of 125 I, 137 Cs, and 85 Sr in organic-rich surface soil and organic-poor subsurface soil of a pasture and an urban forest near a spent-nuclear-fuel reprocessing plant in Rokkasho, Japan. K d of 137 Cs was highly correlated with water-extractable K + . K d of 85 Sr was highly correlated with water-extractable Ca 2+ and SOC. K d of 125 I - was low in organic-rich surface soil, high slightly below the surface, and lowest in the deepest soil. This kinked distribution pattern differed from the gradual decrease of the other radionuclides. The thickness of the high- 125 I - K d middle layer (i.e., with high radioiodide retention ability) differed between sites. K d of 125 I - was significantly correlated with K d of soil organic carbon. Our results also showed that the layer thickness is controlled by the ratio of K d -OC between surface and subsurface soils. This finding suggests that the addition of SOC might prevent further radioiodide migration down the soil profile. As far as we know, this is the first report to show a strong correlation of a soil characteristic with K d of 125 I - . Further study is needed to clarify how radioiodide is retained and migrates in soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Long-term trends of surface ozone and its influencing factors at the Mt. Waliguan GAW station, China - Part 1: Overall trends and characteristics

    Science.gov (United States)

    Xu, W. Y.; Lin, W. L.; Xu, X. B.; Tang, J.; Huang, J. Q.; Wu, H.; Zhang, X. C.

    2015-11-01

    Tropospheric ozone is an important atmospheric oxidant, greenhouse gas and atmospheric pollutant at the same time. The level of tropospheric ozone, particularly in the surface layer, is impacted by emissions of precursors and is subjected to meteorological conditions. Due its importance, the long-term variation trend of baseline ozone is highly needed for environmental and climate change assessment. So far, studies about the long-term trends of ozone at representative sites are mainly available for European and North American sites. Similar studies are lacking for China, a country with rapid economic growth for recent decades, and many other developing countries. To uncover the long-term characteristics and trends of baseline surface ozone, concentration in western China, measurements at a global baseline Global Atmospheric Watch (GAW) station in the north-eastern Tibetan Plateau region (Mt. Waliguan) for the period of 1994 to 2013 were analysed in this study, using a modified Mann-Kendall test and the Hilbert-Huang Transform analysis for the trend and periodicity analysis, respectively. Results reveal higher surface ozone during the night and lower during the day at Waliguan, due to mountain-valley breezes. A seasonal maximum in summer was found, which was probably caused by enhanced stratosphere-to-troposphere exchange events and/or by tropospheric photochemistry. Analysis suggests that there is a season-diurnal cycle in the three-dimensional winds on top of Mt. Waliguan. Season-dependent daytime and nighttime ranges of 6 h were determined based on the season-diurnal cycle in the three-dimensional winds and were used to sort subsets of ozone data for trend analysis. Significant increasing trends in surface ozone were detected for both daytime (1.5-2.7 ppbv 10 a-1) and nighttime (1.3-2.9 ppbv 10 a-1). Autumn and spring revealed the largest increase rates, while summer and winter showed relatively weaker increases. The HHT spectral analysis confirmed the increasing

  19. Stress-intensity factors for surface cracks in pipes: a computer code for evaluation by use of influence functions. Final report

    International Nuclear Information System (INIS)

    Dedhia, D.D.; Harris, D.O.

    1982-06-01

    A user-oriented computer program for the evaluation of stress intensity factors for cracks in pipes is presented. Stress intensity factors for semi-elliptical, complete circumferential and long longitudinal cracks can be obtained using this computer program. The code is based on the method of influence functions which makes it possible to treat arbitrary stresses on the plane of the crack. The stresses on the crack plane can be entered as a mathematical or tabulated function. A user's manual is included in this report. Background information is also included

  20. Vibrational dynamics and band structure of methyl-terminated Ge(111)

    International Nuclear Information System (INIS)

    th Street, Chicago, Illinois 60637 (United States))" data-affiliation=" (The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States))" >Hund, Zachary M.; th Street, Chicago, Illinois 60637 (United States))" data-affiliation=" (The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States))" >Nihill, Kevin J.; th Street, Chicago, Illinois 60637 (United States))" data-affiliation=" (The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States))" >Sibener, S. J.; Campi, Davide; Bernasconi, M.; Wong, Keith T.; Lewis, Nathan S.; Benedek, G.

    2015-01-01

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD 3 -Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH 3 -Ge(111) and CH 3 -Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers

  1. Vibrational dynamics and band structure of methyl-terminated Ge(111)

    Energy Technology Data Exchange (ETDEWEB)

    Hund, Zachary M.; Nihill, Kevin J.; Sibener, S. J., E-mail: s-sibener@uchicago.edu [The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57" t" h Street, Chicago, Illinois 60637 (United States); Campi, Davide; Bernasconi, M. [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Wong, Keith T.; Lewis, Nathan S. [Division of Chemistry and Chemical Engineering, Beckman Institute and Kavli Nanoscience Institute, California Institute of Technology, 210 Noyes Laboratory, 127-72, Pasadena, California 91125 (United States); Benedek, G. [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Donostia International Physics Center (DIPC), Universidad del País Vasco (EHU), 20018 Donostia/San Sebastian (Spain)

    2015-09-28

    A combined synthesis, experiment, and theory approach, using elastic and inelastic helium atom scattering along with ab initio density functional perturbation theory, has been used to investigate the vibrational dynamics and band structure of a recently synthesized organic-functionalized semiconductor interface. Specifically, the thermal properties and lattice dynamics of the underlying Ge(111) semiconductor crystal in the presence of a commensurate (1 × 1) methyl adlayer were defined for atomically flat methylated Ge(111) surfaces. The mean-square atomic displacements were evaluated by analysis of the thermal attenuation of the elastic He diffraction intensities using the Debye-Waller model, revealing an interface with hybrid characteristics. The methyl adlayer vibrational modes are coupled with the Ge(111) substrate, resulting in significantly softer in-plane motion relative to rigid motion in the surface normal. Inelastic helium time-of-flight measurements revealed the excitations of the Rayleigh wave across the surface Brillouin zone, and such measurements were in agreement with the dispersion curves that were produced using density functional perturbation theory. The dispersion relations for H-Ge(111) indicated that a deviation in energy and lineshape for the Rayleigh wave was present along the nearest-neighbor direction. The effects of mass loading, as determined by calculations for CD{sub 3}-Ge(111), as well as by force constants, were less significant than the hybridization between the Rayleigh wave and methyl adlayer librations. The presence of mutually similar hybridization effects for CH{sub 3}-Ge(111) and CH{sub 3}-Si(111) surfaces extends the understanding of the relationship between the vibrational dynamics and the band structure of various semiconductor surfaces that have been functionalized with organic overlayers.

  2. Smal-Scale Spatial Differences in Supply-Side Ecology of Barnacle Larvae Involves a Complex Suite of Factors (Including Surface Tide, Internal Tides And Surface Winds) in Baja California

    Science.gov (United States)

    Valencia, A.; Ladah, L. B.

    2016-02-01

    The objective of this study was to quantify and compare the daily settlement rate of barnacle larvae of Chthamalus spp. at small spatial scales ( 1 km) at three sites with unique geomorphology. Simultaneously, water-column temperature, currents, and coastal winds were measured to detect potential physical transport mechanisms responsible for supply of planktonic larvae to the coast. Autocorrelation artifacts in the environmental and settlement time series were removed with the Autoregressive Integrated Moving Average (ARIMA) and their residuals were used to perform a Principal Component Analysis (PCA). This analysis was carried out to determine the independent modes of variability in the environmental forcing mechanisms that may explain the settlement patterns. We found synchronous settlement pulses occurring throughout the study. Settlement at the wave exposed site was only associated to the wind-forcing mode and not to internal waves, which had not been detected previously and was surprising, considering the strong semidiurnal internal tide at this site. Settlement at both the reef-bounded site and the inside-bay site associated to vertical isotherm displacements, thereby suggesting the importance of internal waves for supply-side ecology at these more southern sites. Our results suggest that a complex suite of factors may interact to result in larval supply at the same site, and that larval supply at nearby sites may be forced by different factors due to differences in geomorphology and/or bathymetry, explaining spatial heterogeneity often detected in larval supply and settlement.

  3. Acridine orange adsorption by zinc oxide/almond shell activated carbon composite: Operational factors, mechanism and performance optimization using central composite design and surface modeling.

    Science.gov (United States)

    Zbair, M; Anfar, Z; Ait Ahsaine, H; El Alem, N; Ezahri, M

    2018-01-15

    Zinc Oxide/Activated Carbon Powder was used for the adsorptive removal of Acridine Orange dye (AO) from aqueous solution. The prepared composite material was characterized using XRD, XPS, SEM, EDS, FTIR, XRF, Raman, BET surface area and TGA/DTA. The adsorption isotherms, kinetics and thermodynamic studies of AO onto the ZnO-AC were thoroughly analyzed. The kinetic modeling data revealed that the adsorption of AO has a good adjustment to the pseudo-second-order model. Langmuir isotherm model is better fitted for adsorption data and the maximum adsorption capacity was found to be 909.1 mg/g at 313 K. The negative values of ΔG showed the spontaneous nature of the AO adsorption onto ZnO-AC. The results indicated the adsorption was pH dependent which is mainly governed by electrostatic attraction, hydrogen bonding and π-π interaction. Reusability test showed a low decrease in the removal performance of ZnO-AC due to the mesopore filling mechanism confirmed by BET analysis after adsorption. Also, thermal regeneration could deposit AO dye on the surface of the composite leading to the efficiency decrease. Finally, the effect of various parameters such as pH, temperature, contact time and initial dye concentration was studied using response surface methodology (RSM). The model predicted a maximum AO removal (99.42 ± 0.57%) under the optimum conditions, which was very close to the experimental value (99.32 ± 0.18%). Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. To ecological-sanitary essessment of the importance of surface-active substances as anthropogenic factor in the Chernobyl' NPP 30-km zone

    International Nuclear Information System (INIS)

    Mudryj, I.V.; Raetskaya, E.V.; Golenkova, L.G.

    1992-01-01

    Sociological analysis dealing with studying attitude of the personnel working in the duty-idle regime towards usage of special clothes treated with synthetic detergents is realized. The surface-active substances (SAS) arc adsorbed by laudered underclothes (8-17 mug/cm 2 ) and can cause skin irritation during wearing. 77% of personnel engaged in public catering and 86% of that working in special laundry were questioned. It is revealed that presence of SAS traces on special clothes gives unfavourable effect on skin covers of the persons questioned (>68%)

  5. 城市地表温度热岛影响因素研究进展%An Overview and Perspective about Causative Factors of Surface Urban Heat Island Effects

    Institute of Scientific and Technical Information of China (English)

    谢苗苗; 王仰麟; 付梅臣

    2011-01-01

    城市地表温度热岛是城市生态环境效应研究的热点之一,其影响因素研究为缓解城市热岛带来的负效应、促进城市可持续发展提供依据.本文系统回顾了国内外关于城市地表温度热岛影响因素的研究进展.首先结合热岛效应表征的地表能量过程,基于景观生态学格局-过程理论,从地表能量吸收释放、转换及传输3种过程中归纳热岛效应的影响机理,分别对应地表覆盖、人为活动和景观格局特征3方面影响因素;其次,从影响因素的3个方面分析了近年来的研究进展,并比较了国内外地表温度热岛综合影响因素研究领域的异同;最后探讨了研究进展与热岛效应影响机理研究的差距,提出利用多源数据深化城市热岛效应的机理性与综合影响因素研究,以期为制定热岛效应缓解策略有所启示.%Urban heat island (UHI) is a hotspot in the study about urban ecological and environmental effects. UHI effects are caused by multiple factors, and the synthesized mechanism study can supply a foundation to release the negative effects of UHI.This study proposes a theory framework for causative factors of surface urban heat island (SUHI) by analyzing the process of surface energy on the basis of landscape ecology. Since surface temperature represents the process of surface energy, we examine the causative factors of this process, which includes energy absorption/emission, energy translation, and energy transmission. The internal and external progresses on each kind of causative factors are reviewed in this study. We also compare the internal studies on synthesized mechanism of SUHI with external studies. By the comparison of progresses of causative factor studies and the mechanism of SUHI, we deduce the prospect on this field.The energy absorption and emission of surface represent the ability to absorb solar shortˉwave radiation, and the capacity to emit earth' s surface longˉwave radiation

  6. SAPO-34/AlMCM-41, as a novel hierarchical nanocomposite: preparation, characterization and investigation of synthesis factors using response surface methodology

    Science.gov (United States)

    Roohollahi, Hossein; Halladj, Rouein; Askari, Sima; Yaripour, Fereydoon

    2018-06-01

    SAPO-34/AlMCM-41, as a new hierarchical nanocomposite was successfully synthesized via hydrothermal and dry-gel conversion. In an experimental and statistical study, effect of five input parameters including synthesis period, drying temperature, NaOH/Si, water/dried-gel and SAPO% were investigated on range-order degree of mesochannels and the relative crystallinity. X-ray diffraction (XRD) patterns were recorded to characterize the ordered AlMCM-41 and crystalline SAPO-34 structures. Nitrogen adsorption-desorption technique, scanning electron microscopy (SEM), field-emission SEM (FESEM) equipped with an energy-dispersive X-ray spectroscopy (EDS-Map) and transmission electron microscopy (TEM) were used to study the textural properties, morphology and surface elemental composition. Two reduced polynomials were fitted to the responses with good precision. Further, based on analysis of variances, SAPO% and time duration of dry-gel conversion were observed as the most effective parameters on the composite structure. The hierarchical porosity, narrow pore size distribution, high external surface area and large specific pore volume were of interesting characteristics for this novel nanocomposite.

  7. A Comparison of Response Surface Methodology and a One-Factor-At-A-Time Approach as Calibration Techniques for the Bioplume-II Simulation Model of Contaminant Biodegradation

    Science.gov (United States)

    1995-12-01

    Technology, 26:1404-1410 (July 1992). 4. Atlas , Ronald M. and Richard Bartha . Microbial Ecology , Fundamentals and Applica- tions (3rd Edition). Redwood... microbial metabolic activity. Leahy and Colwell (35:307) note the impact of physical factors on microbial activity. They cite research by Atlas and... Bartha observing that low temperatures inhibit microbial activity and research by Bossert and Bartha observing that higher temperatures increase activity

  8. Proteome analysis identifies the Dpr protein of Streptococcus mutans as an important factor in the presence of early streptococcal colonizers of tooth surfaces.

    Directory of Open Access Journals (Sweden)

    Akihiro Yoshida

    Full Text Available Oral streptococci are primary colonizers of tooth surfaces and Streptococcus mutans is the principal causative agent of dental caries in humans. A number of proteins are involved in the formation of monospecies biofilms by S. mutans. This study analyzed the protein expression profiles of S. mutans biofilms formed in the presence or absence of S. gordonii, a pioneer colonizer of the tooth surface, by two-dimensional gel electrophoresis (2-DE. After identifying S. mutans proteins by Mass spectrometric analysis, their expression in the presence of S. gordonii was analyzed. S. mutans was inoculated with or without S. gordonii DL1. The two species were compartmentalized using 0.2-μl Anopore membranes. The biofilms on polystyrene plates were harvested, and the solubilized proteins were separated by 2-DE. When S. mutans biofilms were formed in the presence of S. gordonii, the peroxide resistance protein Dpr of the former showed 4.3-fold increased expression compared to biofilms that developed in the absence of the pioneer colonizer. In addition, we performed a competition assay using S. mutans antioxidant protein mutants together with S. gordonii and other initial colonizers. Growth of the dpr-knockout S. mutans mutant was significantly inhibited by S. gordonii, as well as by S. sanguinis. Furthermore, a cell viability assay revealed that the viability of the dpr-defective mutant was significantly attenuated compared to the wild-type strain when co-cultured with S. gordonii. Therefore, these results suggest that Dpr might be one of the essential proteins for S. mutans survival on teeth in the presence of early colonizing oral streptococci.

  9. Proteome Analysis Identifies the Dpr Protein of Streptococcus mutans as an Important Factor in the Presence of Early Streptococcal Colonizers of Tooth Surfaces

    Science.gov (United States)

    Yoshida, Akihiro; Niki, Mamiko; Yamamoto, Yuji; Yasunaga, Ai; Ansai, Toshihiro

    2015-01-01

    Oral streptococci are primary colonizers of tooth surfaces and Streptococcus mutans is the principal causative agent of dental caries in humans. A number of proteins are involved in the formation of monospecies biofilms by S. mutans. This study analyzed the protein expression profiles of S. mutans biofilms formed in the presence or absence of S. gordonii, a pioneer colonizer of the tooth surface, by two-dimensional gel electrophoresis (2-DE). After identifying S. mutans proteins by Mass spectrometric analysis, their expression in the presence of S. gordonii was analyzed. S. mutans was inoculated with or without S. gordonii DL1. The two species were compartmentalized using 0.2-μl Anopore membranes. The biofilms on polystyrene plates were harvested, and the solubilized proteins were separated by 2-DE. When S. mutans biofilms were formed in the presence of S. gordonii, the peroxide resistance protein Dpr of the former showed 4.3-fold increased expression compared to biofilms that developed in the absence of the pioneer colonizer. In addition, we performed a competition assay using S. mutans antioxidant protein mutants together with S. gordonii and other initial colonizers. Growth of the dpr-knockout S. mutans mutant was significantly inhibited by S. gordonii, as well as by S. sanguinis. Furthermore, a cell viability assay revealed that the viability of the dpr-defective mutant was significantly attenuated compared to the wild-type strain when co-cultured with S. gordonii. Therefore, these results suggest that Dpr might be one of the essential proteins for S. mutans survival on teeth in the presence of early colonizing oral streptococci. PMID:25816242

  10. Factors affecting long-term trends in surface-water quality in the Gwynns Falls watershed, Baltimore City and County, Maryland, 1998–2016

    Science.gov (United States)

    Majcher, Emily H.; Woytowitz, Ellen L.; Reisinger, Alexander J.; Groffman, Peter M.

    2018-03-30

    Factors affecting water-quality trends in urban streams are not well understood, despite current regulatory requirements and considerable ongoing investments in gray and green infrastructure. To address this gap, long-term water-quality trends and factors affecting these trends were examined in the Gwynns Falls, Maryland, watershed during 1998–2016 in cooperation with Blue Water Baltimore. Data on water-quality constituents and potential factors of influence were obtained from multiple sources and compiled for analysis, with a focus on data collected as part of the National Science Foundation funded Long-Term Ecological Research project, the Baltimore Ecosystem Study.Variability in climate (specifically, precipitation) and land cover can overwhelm actions taken to improve water quality and can present challenges for meeting regulatory goals. Analysis of land cover during 2001–11 in the Gwynns Falls watershed indicated minimal change during the study time frame; therefore, land-cover change is likely not a factor affecting trends in water quality. However, a modest increase in annual precipitation and a significant increase in winter precipitation were apparent in the region. A higher proportion of runoff producing storms was observed in the winter and a lower proportion in the summer, indicating that climate change may affect water quality in the watershed. The increase in precipitation was not reflected in annual or seasonal trends of streamflow in the watershed. Nonetheless, these precipitation changes may exacerbate the inflow and infiltration of water to gray infrastructure and reduce the effectiveness of green infrastructure. For streamflow and most water-quality constituents examined, no discernable trends were noted over the timeframe examined. Despite the increases in precipitation, no trends were observed for annual or seasonal discharge at the various sites within the study area. In some locations, nitrate, phosphate, and total nitrogen show downward

  11. Experimental and theoretical study of rotationally inelastic diffraction of H2(D2) from methyl-terminated Si(111)

    International Nuclear Information System (INIS)

    Nihill, Kevin J.; Hund, Zachary M.; Sibener, S. J.; Muzas, Alberto; Cueto, Marcos del; Díaz, Cristina; Frankcombe, Terry; Plymale, Noah T.; Lewis, Nathan S.; Martín, Fernando

    2016-01-01

    Fundamental details concerning the interaction between H 2 and CH 3 –Si(111) have been elucidated by the combination of diffractive scattering experiments and electronic structure and scattering calculations. Rotationally inelastic diffraction (RID) of H 2 and D 2 from this model hydrocarbon-decorated semiconductor interface has been confirmed for the first time via both time-of-flight and diffraction measurements, with modest j = 0 → 2 RID intensities for H 2 compared to the strong RID features observed for D 2 over a large range of kinematic scattering conditions along two high-symmetry azimuthal directions. The Debye-Waller model was applied to the thermal attenuation of diffraction peaks, allowing for precise determination of the RID probabilities by accounting for incoherent motion of the CH 3 –Si(111) surface atoms. The probabilities of rotationally inelastic diffraction of H 2 and D 2 have been quantitatively evaluated as a function of beam energy and scattering angle, and have been compared with complementary electronic structure and scattering calculations to provide insight into the interaction potential between H 2 (D 2 ) and hence the surface charge density distribution. Specifically, a six-dimensional potential energy surface (PES), describing the electronic structure of the H 2 (D 2 )/CH 3 −Si(111) system, has been computed based on interpolation of density functional theory energies. Quantum and classical dynamics simulations have allowed for an assessment of the accuracy of the PES, and subsequently for identification of the features of the PES that serve as classical turning points. A close scrutiny of the PES reveals the highly anisotropic character of the interaction potential at these turning points. This combination of experiment and theory provides new and important details about the interaction of H 2 with a hybrid organic-semiconductor interface, which can be used to further investigate energy flow in technologically relevant systems.

  12. Environmental factors affecting the accuracy of surface fluxes from a two-source model in Mediterranean drylands: Upscaling instantaneous to daytime estimates

    DEFF Research Database (Denmark)

    Morillas, Laura; Villagarcia, Luis; Domingo, Francisco

    2014-01-01

    latent heat flux, LE, if expressed in energy terms), making sensible heat flux (H) the dominant turbulent heat flux. In this study, we present a detailed analysis of the main environmental factors affecting the TSM effectiveness under such challenging conditions. The accuracy of the TSM, evaluated via...... of the TSM (TSMP) showed overall lower errors and a lower tendency to underestimate at high H values, but the series resistances scheme of the TSM (TSMS) increased the model accuracy under some specific circumstances such as low energy supply and atmospheric neutral conditions. Finally, two extrapolation...

  13. Evaluación de los factores de riesgo y los tipos de superficie para el desarrollo de las úlceras por presión en el enfermo crítico Assessment of risk factors and the types of surface for the development of pressure ulcers on critical ill patients

    Directory of Open Access Journals (Sweden)

    Concepció Fuentes i Pumarola

    2007-06-01

    Full Text Available Objetivos: Evaluar los factores de riesgo y los tipos de superficie para el desarrollo de las úlceras por presión (UPP en el enfermo crítico ingresado en una unidad de cuidados intensivos (UCI. Material y métodos: Estudio prospectivo de incidencia de UPP. Población: Enfermos ingresados en una UCI con EMINA© de alto riesgo, estancia mínima de 48 horas y que no presentaran UPP al ingreso. Se registraron los datos demográficos, de gravedad al ingreso (SAPS II y APACHE III, diabetes, estado séptico, ventilación mecánica, incidencia y grado de UPP, y tipo de superficie de apoyo (alternante [SA] o estática [SE]. Conclusiones: Los factores de riesgo asociados con el desarrollo de UPP en el enfermo crítico fueron la edad, la estancia media y el tipo de superficie de apoyo, siendo muy significativa la disminución de la incidencia de UPP con las superficies alternantes.Objectives: To assess the risk factors and the types of surface for the development of pressure ulcers (PU on critical ill patients in an Intensive Care Unit (ICU. Material and methods: Prospective study about the incidence of PU. Population: All patients on ICU with EMINA® of high risk, who stay 48 h. at least and don't have PU in the moment of admission. Information about demographic characteristics, gravity in the moment of admitting was recorded: SAPS II and APACHE III, diabetes, sepsis, mechanical ventilation, incidence and graduation of PU, and the type of support surface: alternate (AS or static (SS. Conclusions: The risk factors associated with the development of PU on critical ill patients were the age, the average time in ICU and the type of support surface, being the reduction on incidence of PU with the alternate surfaces very important.

  14. Radiative heat exchange between surfaces

    International Nuclear Information System (INIS)

    Yener, Y.; Yuncu, H.

    1987-01-01

    The geometrical features of radiative heat exchange between surfaces are discussed first by developing various radiation shape factor relations. The governing equations for enclosures with diffusely emitting and diffusely reflecting surfaces, as well as the equations for enclosures with gray surfaces having specular component of reflectivity are introduced next. Finally, a simplified model for enclosures with isothermal surfaces under the assumption of uniform radiosity over the surfaces is discussed, and various working relations for different conditions are presented

  15. Multiscale virtual particle based elastic network model (MVP-ENM) for normal mode analysis of large-sized biomolecules.

    Science.gov (United States)

    Xia, Kelin

    2017-12-20

    In this paper, a multiscale virtual particle based elastic network model (MVP-ENM) is proposed for the normal mode analysis of large-sized biomolecules. The multiscale virtual particle (MVP) model is proposed for the discretization of biomolecular density data. With this model, large-sized biomolecular structures can be coarse-grained into virtual particles such that a balance between model accuracy and computational cost can be achieved. An elastic network is constructed by assuming "connections" between virtual particles. The connection is described by a special harmonic potential function, which considers the influence from both the mass distributions and distance relations of the virtual particles. Two independent models, i.e., the multiscale virtual particle based Gaussian network model (MVP-GNM) and the multiscale virtual particle based anisotropic network model (MVP-ANM), are proposed. It has been found that in the Debye-Waller factor (B-factor) prediction, the results from our MVP-GNM with a high resolution are as good as the ones from GNM. Even with low resolutions, our MVP-GNM can still capture the global behavior of the B-factor very well with mismatches predominantly from the regions with large B-factor values. Further, it has been demonstrated that the low-frequency eigenmodes from our MVP-ANM are highly consistent with the ones from ANM even with very low resolutions and a coarse grid. Finally, the great advantage of MVP-ANM model for large-sized biomolecules has been demonstrated by using two poliovirus virus structures. The paper ends with a conclusion.

  16. Optimization of nutritional and non-nutritional factors involved for production of antimicrobial compounds from Lactobacillus pentosus SJ65 using response surface methodology

    Directory of Open Access Journals (Sweden)

    Appukuttan Saraniya

    2014-01-01

    Full Text Available Bacteriocins from lactic acid bacteria are ribosomal synthesized antibacterial proteins/ peptides having wide range of applications. Lactobacillus pentosus SJ65, isolated from fermented Uttapam batter (used to prepare south Indian pan cake, produces bacteriocin having a broad spectrum of activity against pathogens. Optimization studies are of utmost important to understand the source of utilization and the conditions to enhance the production of metabolites. In the present study, an attempt was made to identify the parameters involved for maximal production of antimicrobial compounds especially bacteriocin from the isolate L. pentosus SJ65. Initially, optimal conditions, such as incubation period, pH, and temperature were evaluated. Initial screening was done using methodology onevariable-at-a-time (OVAT for various carbon and nitrogen sources. Further evaluation was carried out statistically using Plackett-Burman design and the variables were analyzed using response surface methodology using central composite design. The optimum media using tryptone or soy peptone, yeast extract, glucose, triammonium citrate, MnSO4, dipotassium hydrogen phosphate and tween 80 produced maximum bacteriocin activity.

  17. External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting.

    Science.gov (United States)

    Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

    2013-01-01

    For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13.

  18. Risk Factors for Hepatitis B virus Surface Antigen Positive Prevalence in the Most Migratory Province of Iran: A Matched Case- Control Study

    Directory of Open Access Journals (Sweden)

    Gh. Karimi

    2015-02-01

    Full Text Available Background and Objective: Hepatitis B Virus Infection is one of the most common infectious diseases and also among the world's top ten causes of this group diseases-related mortality, so that 500,000 to 1.2 million annually die due to the consequences of this infection such as chronic hepatitis, cirrhosis and hepatocellular carcinoma. This study was conducted to determine risk factors for HBsAg-positive prevalence in Alborz Province. Materials and Methods: A 1:1 matched case-control study, 213 of cases reported HBsAg positive to the Alborz University of Medical Sciences in 2013 as case group with 213 of family members of patients with hepatitis C who have serologic markers Anti- HCV negative and HBsAg negative as the control group, were compared in terms of demographic characteristics, History of high risk behaviors, Iatrogenic exposures, community exposures and history of liver disease. Statistical analysis using logistic regression was performed by SPSS software version 18. Results: Reported cases with a mean age of 37.6±15.5 years, was more relevant to marginalized, immigrants and male gender. Nationality, being married, low level of education, family history of HBsAg positive, history of non-intravenous drug abuse, alcohol consumption, history of prison, employment in high risk occupations, sharing of razor, injuries with contaminated sharp instruments and history of jaundice in mother were found to be independent risk factors for HBsAg positive prevalence (OR: 0.27, 3.61, 1.68, 18.04, 12.21, 2.9, 7.52, 2.47, 5.55, 21.48, 11.3, respectively. Conclusions: Unfavorable situation of the marginalized and the prisoners, imported illegal immigrants, especially Afghans can be extended to high-risk behaviors and the threat of a disease surveillance system. Screening and vaccination aforementioned groups, health promotion of the marginalized and raise public knowledge is necessary.

  19. Minimal surfaces

    CERN Document Server

    Dierkes, Ulrich; Sauvigny, Friedrich; Jakob, Ruben; Kuster, Albrecht

    2010-01-01

    Minimal Surfaces is the first volume of a three volume treatise on minimal surfaces (Grundlehren Nr. 339-341). Each volume can be read and studied independently of the others. The central theme is boundary value problems for minimal surfaces. The treatise is a substantially revised and extended version of the monograph Minimal Surfaces I, II (Grundlehren Nr. 295 & 296). The first volume begins with an exposition of basic ideas of the theory of surfaces in three-dimensional Euclidean space, followed by an introduction of minimal surfaces as stationary points of area, or equivalently

  20. Electron density distribution in ferromagnetic nickel: A γ -ray diffraction study

    Science.gov (United States)

    Jauch, W.; Reehuis, M.

    2008-12-01

    High-accuracy single-crystal structure factors, complete up to sinθ/λ=1.9Å-1 , have been measured from ferromagnetic nickel at 295 K using 316.5-keV gamma radiation. The experimental uncertainty of the structure factors is of the order of 10 millielectrons per atom for all data. A detailed description of the electron density distribution is presented in terms of a multipolar atomic deformation model. Achievement of a reliable Debye-Waller factor is of vital importance in this context. The charge asphericity is due to an excess eg orbital occupancy of 43.4(2)%. The 3d shell in the metal is contracted by 2.07(5)% relative to the free atom. The results are discussed and compared with earlier experimental and theoretical works. In contrast to bcc Cr and Fe, solid-state effects are less pronounced in fcc Ni. Clear disentanglement between the 3d and 4s valence electrons could be accomplished for the first time. The general expectation that the number of 3d electrons in the metal should be increased as compared to the atom was confirmed in the case of iron by combining spin and charge-density data. In the case of nickel, it is rejected as revealed by the γ -ray data alone. Only with the d8 configuration, consistency is achieved between observed and refined mosaic widths of the sample crystal. A 3d8 configuration implies that the majority-spin d band cannot be full. Strong support is lent to a localized atomic character of the valence electrons.

  1. Organotin compounds in surface sediments of the Southern Baltic coastal zone: a study on the main factors for their accumulation and degradation.

    Science.gov (United States)

    Filipkowska, Anna; Kowalewska, Grażyna; Pavoni, Bruno

    2014-02-01

    Sediment samples were collected in the Gulf of Gdańsk, and the Vistula and Szczecin Lagoons-all located in the coastal zone of the Southern Baltic Sea-just after the total ban on using harmful organotins in antifouling paints on ships came into force, to assess their butyltin and phenyltin contamination extent. Altogether, 26 sampling stations were chosen to account for different potential exposure to organotin pollution and environmental conditions: from shallow and well-oxygenated waters, shipping routes and river mouths, to deep and anoxic sites. Additionally, the organic carbon content, pigment content, and grain size of all the sediment samples were determined, and some parameters of the near-bottom water (oxygen content, salinity, temperature) were measured as well. Total concentrations of butyltin compounds ranged between 2 and 182 ng Sn g(-1) d.w., whereas phenyltins were below the detection limit. Sediments from the Gulf of Gdańsk and Vistula Lagoon were found moderately contaminated with tributyltin, whereas those from the Szczecin Lagoon were ranked as highly contaminated. Butyltin degradation indices prove a recent tributyltin input into the sediments adjacent to sites used for dumping for dredged harbor materials and for anchorage in the Gulf of Gdańsk (where two big international ports are located), and into those collected in the Szczecin Lagoon. Essential factors affecting the degradation and distribution of organotins, based on significant correlations between butyltins and environmental variables, were found in the study area.

  2. Rumble surfaces

    CSIR Research Space (South Africa)

    National Institute for Transport and Road

    1977-01-01

    Full Text Available Rumble surfaces are intermittent short lengths of coarse-textured road surfacings on which vehicle tyres produce a rumbling sound. used in conjunction with appropriate roadsigns and markings, they can reduce accidents on rural roads by alerting...

  3. Surface thermodynamics

    International Nuclear Information System (INIS)

    Garcia-Moliner, F.

    1975-01-01

    Basic thermodynamics of a system consisting of two bulk phases with an interface. Solid surfaces: general. Discussion of experimental data on surface tension and related concepts. Adsorption thermodynamics in the Gibbsian scheme. Adsorption on inert solid adsorbents. Systems with electrical charges: chemistry and thermodynamics of imperfect crystals. Thermodynamics of charged surfaces. Simple models of charge transfer chemisorption. Adsorption heat and related concepts. Surface phase transitions

  4. Transforming growth factor β-induced superficial zone protein accumulation in the surface zone of articular cartilage is dependent on the cytoskeleton.

    Science.gov (United States)

    McNary, Sean M; Athanasiou, Kyriacos A; Reddi, A Hari

    2014-03-01

    The phenotype of articular chondrocytes is dependent on the cytoskeleton, specifically the actin microfilament architecture. Articular chondrocytes in monolayer culture undergo dedifferentiation and assume a fibroblastic phenotype. This process can be reversed by altering the actin cytoskeleton by treatment with cytochalasin. Whereas dedifferentiation has been studied on chondrocytes isolated from the whole cartilage, the effects of cytoskeletal alteration on specific zones of cells such as superficial zone chondrocytes are not known. Chondrocytes from the superficial zone secrete superficial zone protein (SZP), a lubricating proteoglycan that reduces the coefficient of friction of articular cartilage. A better understanding of this phenomenon may be useful in elucidating chondrocyte dedifferentiation in monolayer and accumulation of the cartilage lubricant SZP, with an eye toward tissue engineering functional articular cartilage. In this investigation, the effects of cytoskeletal modulation on the ability of superficial zone chondrocytes to secrete SZP were examined. Primary superficial zone chondrocytes were cultured in monolayer and treated with a combination of cytoskeleton modifying reagents and transforming growth factor β (TGFβ) 1, a critical regulator of SZP production. Whereas cytochalasin D maintains the articular chondrocyte phenotype, the hallmark of the superficial zone chondrocyte, SZP, was inhibited in the presence of TGFβ1. A decrease in TGFβ1-induced SZP accumulation was also observed when the microtubule cytoskeleton was modified using paclitaxel. These effects of actin and microtubule alteration were confirmed through the application of jasplakinolide and colchicine, respectively. As Rho GTPases regulate actin organization and microtubule polymerization, we hypothesized that the cytoskeleton is critical for TGFβ-induced SZP accumulation. TGFβ-mediated SZP accumulation was inhibited by small molecule inhibitors ML141 (Cdc42), NSC23766 (Rac1

  5. Brain-derived neurotrophic factor (BDNF) induces sustained intracellular Ca2+ elevation through the up-regulation of surface transient receptor potential 3 (TRPC3) channels in rodent microglia.

    Science.gov (United States)

    Mizoguchi, Yoshito; Kato, Takahiro A; Seki, Yoshihiro; Ohgidani, Masahiro; Sagata, Noriaki; Horikawa, Hideki; Yamauchi, Yusuke; Sato-Kasai, Mina; Hayakawa, Kohei; Inoue, Ryuji; Kanba, Shigenobu; Monji, Akira

    2014-06-27

    Microglia are immune cells that release factors, including proinflammatory cytokines, nitric oxide (NO), and neurotrophins, following activation after disturbance in the brain. Elevation of intracellular Ca(2+) concentration ([Ca(2+)]i) is important for microglial functions such as the release of cytokines and NO from activated microglia. There is increasing evidence suggesting that pathophysiology of neuropsychiatric disorders is related to the inflammatory responses mediated by microglia. Brain-derived neurotrophic factor (BDNF) is a neurotrophin well known for its roles in the activation of microglia as well as in pathophysiology and/or treatment of neuropsychiatric disorders. In this study, we sought to examine the underlying mechanism of BDNF-induced sustained increase in [Ca(2+)]i in rodent microglial cells. We observed that canonical transient receptor potential 3 (TRPC3) channels contribute to the maintenance of BDNF-induced sustained intracellular Ca(2+) elevation. Immunocytochemical technique and flow cytometry also revealed that BDNF rapidly up-regulated the surface expression of TRPC3 channels in rodent microglial cells. In addition, pretreatment with BDNF suppressed the production of NO induced by tumor necrosis factor α (TNFα), which was prevented by co-adiministration of a selective TRPC3 inhibitor. These suggest that BDNF induces sustained intracellular Ca(2+) elevation through the up-regulation of surface TRPC3 channels and TRPC3 channels could be important for the BDNF-induced suppression of the NO production in activated microglia. We show that TRPC3 channels could also play important roles in microglial functions, which might be important for the regulation of inflammatory responses and may also be involved in the pathophysiology and/or the treatment of neuropsychiatric disorders. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. EXAFS characterization of supported metal catalysts in chemically dynamic environments

    International Nuclear Information System (INIS)

    Robota, H.J.

    1991-01-01

    Characterization of catalysts focuses on the identification of an active site responsible for accelerating desirable chemical reactions. The identification, characterization, and selective modification of such sites is fundamental to the development of structure-function relationships. Unfortunately, this goal is far from realized in nearly all catalysts, and particularly in catalysts comprised of small supported metal particles. X-ray absorption spectroscopy (XAS) has had a dramatic effect on our understanding of supported metal particles in their resting state. However, the performance of a catalyst can not be assessed from such simple resting state measurements. Among the factors which influence catalyst performance are the exact catalyst composition, including the support and any modifiers; particle size; catalyst finishing and pretreatment conditions; pressure, composition, and temperature of the operating environment; time. Gaining an understanding of how the structure of a catalytic site can change with such an array of variables requires that we begin to develop measurement methods which are effective under chemically dynamic conditions. Ideally, it should be possible to obtain a full X-ray absorption spectrum of each element thought to have a causal relationship with observed catalyst properties. From these spectra, we can optimally extract only a relatively limited amount of information which we must then piece together with information derived from other characterization methods and intuition to arrive at a hypothetical structure of the operating catalyst. Information about crystallinity, homogeneity, and general disorder can be obtained from the Debye-Waller factor. Finally, through analogy with known compounds, the electronic structure of the active atoms can be inferred from near edge absorption features

  7. Spatial Variability of Metals in Surface Water and Sediment in the Langat River and Geochemical Factors That Influence Their Water-Sediment Interactions

    Directory of Open Access Journals (Sweden)

    Wan Ying Lim

    2012-01-01

    Full Text Available This paper determines the controlling factors that influence the metals’ behavior water-sediment interaction facies and distribution of elemental content (75As, 111Cd, 59Co, 52Cr, 60Ni, and 208Pb in water and sediment samples in order to assess the metal pollution status in the Langat River. A total of 90 water and sediment samples were collected simultaneously in triplicate at 30 sampling stations. Selected metals were analyzed using ICP-MS, and the metals’ concentration varied among stations. Metal concentrations of water ranged between 0.08–24.71 μg/L for As, <0.01–0.53 μg/L for Cd, 0.06–6.22 μg/L for Co, 0.32–4.67 μg/L for Cr, 0.80–24.72 μg/L for Ni, and <0.005–6.99 μg/L for Pb. Meanwhile, for sediment, it ranged between 4.47–30.04 mg/kg for As, 0.02–0.18 mg/kg for Cd, 0.87–4.66 mg/kg for Co, 4.31–29.04 mg/kg for Cr, 2.33–8.25 mg/kg for Ni and 5.57–55.71 mg/kg for Pb. The average concentration of studied metals in the water was lower than the Malaysian National Standard for Drinking Water Quality proposed by the Ministry of Health. The average concentration for As in sediment was exceeding ISQG standards as proposed by the Canadian Sediment Quality Guidelines. Statistical analyses revealed that certain metals (As, Co, Ni, and Pb were generally influenced by pH and conductivity. These results are important when making crucial decisions in determining potential hazardous levels of these metals toward humans.

  8. Universal divergenceless scaling between structural relaxation and caged dynamics in glass-forming systems.

    Science.gov (United States)

    Ottochian, A; De Michele, C; Leporini, D

    2009-12-14

    On approaching the glass transition, the microscopic kinetic unit spends increasing time rattling in the cage of the first neighbors, whereas its average escape time, the structural relaxation time tau(alpha), increases from a few picoseconds up to thousands of seconds. A thorough study of the correlation between tau(alpha) and the rattling amplitude, expressed by the Debye-Waller factor, was carried out. Molecular-dynamics simulations of both a model polymer system and a binary mixture were performed by varying the temperature, the density rho, the potential and the polymer length to consider the structural relaxation as well as both the rotational and the translation diffusion. The present simulations, together with MD studies on other glassformers, evidence the scaling between the structural relaxation and the caged dynamics. An analytic model of the master curve is developed in terms of two characteristic length scales a(2) (1/2) and sigma(a(2) ) (1/2), pertaining to the distance to be covered by the kinetic unit to reach a transition state. The model does not imply tau(alpha) divergences. The comparison with the experiments supports the numerical evidence over a range of relaxation times as wide as about eighteen orders of magnitude. A comparison with other scaling and correlation procedures is presented. In particular, the density scaling of the length scales a(2) (1/2), sigma(a(2) ) (1/2) proportional to rho(-1/3) is shown to be not supported by the present simulations. The study suggests that the equilibrium and the moderately supercooled states of the glassformers possess key information on the huge slowing-down of their relaxation close to the glass transition. The latter, according to the present simulations, exhibits features consistent with the Lindemann melting criterion and the free-volume model.

  9. Relation between interfacial structure and mechanical properties in AlN/TiN bilayers investigated by EXAFS

    International Nuclear Information System (INIS)

    Ersen, O.; Tuilier, M.-H.; Thobor-Keck, A.; Rousselot, C.; Cortes, R.

    2005-01-01

    The relation between the mechanical properties and the structure of AlN/TiN bilayers prepared by reactive magnetron sputtering in the 600 nm range is investigated. Al and Ti K-edge extended X-ray absorption fine structure is used in order to determine the local order around Al and Ti by comparison with 300 nm thick AlN and TiN single layers. The use of this powerful local probe allows the evidence of intermixing between AlN and TiN deposited layers, which is suggested by glow discharge optical emission spectroscopy experiments. The effect of ionic bombardment applied at various steps of the deposition process is studied. The ionic bombardment applied during the deposit induces substantial changes in the absorption spectra that are assigned to a decrease of intermixing and an improvement of local order. Simulations of (Al, Ti)N ternary alloys Al and Ti K-edge absorption spectra for increasing mean occupation factors C Ti (C Al ) of Ti(Al) substituting Al(Ti) in hexagonal AlN (cubic TiN) lattice are performed in order to determine the initial parameters for the fit of the experimental data. The refinements performed by using FEFFIT software demonstrate that an ionic bombardment applied during the deposition phase results in a significant reduction of the number of Al-Ti pairs within the bilayer and an improvement of the local order around Ti and Al, which is quantified by a decrease of the Debye-Waller parameters. This structural evolution is tentatively correlated with the improvement of mechanical properties of the bilayers

  10. Relation between interfacial structure and mechanical properties in AlN/TiN bilayers investigated by EXAFS

    Energy Technology Data Exchange (ETDEWEB)

    Ersen, O. [Equipe de Recherche Mecanique, Materiaux et Procedes de Fabrication, 61, rue Albert Camus, F-68093 Mulhouse (France)]. E-mail: ovidiu.ersen@ipcms.u-strasbg.fr; Tuilier, M.-H. [Equipe de Recherche Mecanique, Materiaux et Procedes de Fabrication, 61, rue Albert Camus, F-68093 Mulhouse (France); Thobor-Keck, A. [Centre de Recherche sur les Ecoulements les Surfaces et les Transferts (UMR CNRS 6000), ITSFC, 4, place Tharradin, BP 71427, F-25211 Montbeliard (France); Rousselot, C. [Centre de Recherche sur les Ecoulements les Surfaces et les Transferts (UMR CNRS 6000), ITSFC, 4, place Tharradin, BP 71427, F-25211 Montbeliard (France); Cortes, R. [Laboratoire de Physique de la Matiere Condensee (UMR CNRS 7643), Ecole Polytechnique, F-91128 Palaiseau cedex (France)

    2005-06-01

    The relation between the mechanical properties and the structure of AlN/TiN bilayers prepared by reactive magnetron sputtering in the 600 nm range is investigated. Al and Ti K-edge extended X-ray absorption fine structure is used in order to determine the local order around Al and Ti by comparison with 300 nm thick AlN and TiN single layers. The use of this powerful local probe allows the evidence of intermixing between AlN and TiN deposited layers, which is suggested by glow discharge optical emission spectroscopy experiments. The effect of ionic bombardment applied at various steps of the deposition process is studied. The ionic bombardment applied during the deposit induces substantial changes in the absorption spectra that are assigned to a decrease of intermixing and an improvement of local order. Simulations of (Al, Ti)N ternary alloys Al and Ti K-edge absorption spectra for increasing mean occupation factors C {sub Ti} (C {sub Al}) of Ti(Al) substituting Al(Ti) in hexagonal AlN (cubic TiN) lattice are performed in order to determine the initial parameters for the fit of the experimental data. The refinements performed by using FEFFIT software demonstrate that an ionic bombardment applied during the deposition phase results in a significant reduction of the number of Al-Ti pairs within the bilayer and an improvement of the local order around Ti and Al, which is quantified by a decrease of the Debye-Waller parameters. This structural evolution is tentatively correlated with the improvement of mechanical properties of the bilayers.

  11. Neutron- and light-scattering studies of the liquid-to-glass and glass-to-glass transitions in dense copolymer micellar solutions

    International Nuclear Information System (INIS)

    Chen Weiren; Chen Sowhsin; Mallamace, Francesco; Glinka, Charles J.; Fratini, Emiliano

    2003-01-01

    Recent mode coupling theory (MCT) calculations show that if a short-range attractive interaction is added to the pure hard sphere system, one may observe a new type of glass originating from the clustering effect (the attractive glass) as a result of the attractive interaction. This is in addition to the known glass-forming mechanism due to the cage effect in the hard sphere system (the repulsive glass). The calculations also indicate that if the range of attraction is sufficiently short compared to the diameter of the particle, within a certain interval of volume fractions where the two glass-forming mechanisms nearly balance each other, varying the external control parameter, the effective temperature, makes the glass-to-liquid-to-glass reentrance and the glass-to-glass transitions possible. Here we present experimental evidence of both transitions, obtained from small-angle neutron-scattering and photon correlation measurements taken from dense L64 copolymer micellar solutions in heavy water. Varying the temperature in certain predicted volume fraction range triggers a sharp transition between these two different types of glass. In particular, according to MCT, there is an end point (called A 3 singularity) of this glass-to-glass transition line, beyond which the long-time dynamics of the two glasses become identical. Our findings confirm this theoretical prediction. Surprisingly, although the Debye-Waller factors, the long-time limit of the coherent intermediate scattering functions, of these two glasses obtained from photon correlation measurements indeed become identical at the predicted volume fraction, they exhibit distinctly different intermediate time relaxation. Furthermore, our experimental results obtained from volume fractions beyond the end point are characterized by the same features as the repulsive glass obtained before the end point. A complete phase diagram giving the boundaries of the structural arrest transitions for L64 micellar system is

  12. Inelastic scattering in condensed matter with high intensity Moessbauer radiation

    International Nuclear Information System (INIS)

    Yelon, W.B.; Schupp, G.

    1990-10-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS 2 , which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support

  13. Gamma scattering in condensed matter with high intensity Moessbauer radiation

    International Nuclear Information System (INIS)

    1990-01-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS 2 , which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support

  14. Inelastic scattering in condensed matter with high intensity moessbauer radiation

    International Nuclear Information System (INIS)

    Yelon, W.B.; Schupp, G.

    1991-05-01

    We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is not fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using Bragg scattering filters to suppress unwanted radiation. These have led to a Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to make a novel independent determination of interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na metal and the charge density wave satellite reflection Debye-Waller factor in TaS 2 , which indicate phason rather than phonon behavior. Using a specially constructed sample cell which enables us to vary temperatures from -10 C to 110 C, we have begun quasielastic diffusion studies in viscous liquids and current results are summarized. Included are the temperature and Q dependence of the scattering in pentadecane and diffusion in glycerol

  15. A unified description of crystalline-to-amorphous transitions

    Energy Technology Data Exchange (ETDEWEB)

    Lam, N.Q.; Okamoto, P.R. [Argonne National Lab., IL (United States); Devanathan, R. [Argonne National Lab., IL (United States)]|[Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Meshii, M. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering

    1993-07-01

    Amorphous metallic alloys can now be synthesized by a variety of solid-state processes demonstrating the need for a more general approach to crystalline-to-amorphous (c-a) transitions. By focusing on static atomic displacements as a measure of chemical and topological disorder, we show that a unified description of c-a transformations can be based on a generalization of the phenomenological melting criterion proposed by Lindemann. The generalized version assumes that melting of a defective crystal occurs whenever the sum of thermal and static mean-square displacements exceeds a critical value identical to that for melting of the defect-free crystal. This implies that chemical or topological disorder measured by static displacements is thermodynamically equivalent to heating, and therefore that the melting temperature of the defective crystal will decrease with increasing amount of disorder. This in turn implies the existence of a critical state of disorder where the melting temperature becomes equal to a glass-transition temperature below which the metastable crystal melts to a glass. The generalized Lindemann melting criterion leads naturally to an interpretation of c-a transformations as defect-induced, low-temperature melting of critically disordered crystals. Confirmation of this criterion is provided by molecular-dynamics simulations of heat-induced melting and of defect-induced amorphization of intermetallic compounds caused either by the production of Frenkel pairs or anti-site defects. The thermodynamic equivalence between static atomic disorder and heating is reflected in the identical softening effects which they have on elastic properties and also in the diffraction analysis of diffuse scattering from disordered crystals, where the effect of static displacements appears as an artificially-enlarged thermal Debye-Waller factor. Predictions of this new, unified approach to melting and amorphization are compared with available experimental information.

  16. Feline glycoprotein A repetitions predominant anchors transforming growth factor beta on the surface of activated CD4(+)CD25(+) regulatory T cells and mediates AIDS lentivirus-induced T cell immunodeficiency.

    Science.gov (United States)

    Miller, Michelle M; Fogle, Jonathan E; Ross, Peter; Tompkins, Mary B

    2013-04-01

    Using the feline immunodeficiency virus (FIV) model for AIDS-lentivirus infection, our laboratory has previously demonstrated that T regulatory (Treg) cell-mediated immune T and B cell dysfunction contributes to lentivirus persistence and chronic disease through membrane bound transforming growth factor beta (mTGFb). Studying Treg cells in the context of infection has been problematic as no inducible marker for activated Treg cells had been identified. However, recent reports in human Treg studies have described a novel protein, glycoprotein A repetitions predominant (GARP), as a unique marker of activated human Treg cells that anchors mTGFb. Herein we extend these studies to the feline Treg system, identifying feline GARP and demonstrating that human and feline GARP proteins are homologous in structure, expression pattern, and ability to form a complex with TGFb. We further demonstrate that GARP and TGFb form a complex on the surface of activated Treg cells and that these GARP(+)TGFb(+) Treg cells are highly efficient suppressor cells. Analysis of expression of this Treg activation marker in the FIV-AIDS model reveals an up-regulation of GARP expressing Treg cells during chronic FIV infection. We demonstrate that the GARP(+) Treg cells from FIV-infected cats suppress T helper cells in vivo and that blocking GARP or TGFb eliminates this suppression. These data suggest that GARP is expressed in complex with TGFb on the surface of activated Treg cells and plays an important role in TGFb(+) Treg-mediated T cell immune suppression during lentivirus infection.

  17. Surface mining

    Science.gov (United States)

    Robert Leopold; Bruce Rowland; Reed Stalder

    1979-01-01

    The surface mining process consists of four phases: (1) exploration; (2) development; (3) production; and (4) reclamation. A variety of surface mining methods has been developed, including strip mining, auger, area strip, open pit, dredging, and hydraulic. Sound planning and design techniques are essential to implement alternatives to meet the myriad of laws,...

  18. Superhydrophobic surfaces

    Science.gov (United States)

    Wang, Evelyn N; McCarthy, Matthew; Enright, Ryan; Culver, James N; Gerasopoulos, Konstantinos; Ghodssi, Reza

    2015-03-24

    Surfaces having a hierarchical structure--having features of both microscale and nanoscale dimensions--can exhibit superhydrophobic properties and advantageous condensation and heat transfer properties. The hierarchical surfaces can be fabricated using biological nanostructures, such as viruses as a self-assembled nanoscale template.

  19. Surface characterization

    Science.gov (United States)

    Mandla A. Tshabalala

    2005-01-01

    Surface properties of wood play an important role when wood is used or processed into different commodities such as siding, joinery, textiles, paper, sorption media or wood composites. Thus, for example, the quality and durability of a wood coating are determined by the surface properties of the wood and the coating. The same is true for wood composites, as the...

  20. Biomechanical aspects of playing surfaces.

    Science.gov (United States)

    Nigg, B M; Yeadon, M R

    1987-01-01

    The purpose of this paper is to discuss some biomechanical aspects of playing surfaces with special focus on (a) surface induced injuries, (b) methodologies used to assess surfaces and (c) findings from various sports. The paper concentrates primarily on questions related to load on the athlete's body. Data from epidemiological studies suggest strongly that the surface is an important factor in the aetiology of injuries. Injury frequencies are reported to be significantly different for different surfaces in several sports. The methodologies used to assess surfaces with respect to load or performance include material tests and tests using experimental subjects. There is only little correlation between the results of these two approaches. Material tests used in many standardized test procedures are not validated which suggests that one should exercise restraint in the interpretation of these results. Point elastic surfaces are widely studied while area elastic surfaces have received little attention to date. Questions of energy losses on sport surfaces have rarely been studied scientifically.

  1. The Impact of UV-dose, Body Surface Area Exposed and Other Factors on Cutaneous Vitamin D Synthesis Measured as Serum 25(OH)D Concentration: Systematic Review and Meta-analysis.

    Science.gov (United States)

    Jager, Nadine; Schöpe, Jakob; Wagenpfeil, Stefan; Bocionek, Peter; Saternus, Roman; Vogt, Thomas; Reichrath, Jörg

    2018-02-01

    To optimize public health campaigns concerning UV exposure, it is important to characterize factors that influence UV-induced cutaneous vitamin D production. This systematic review and meta-analysis investigated the impact of different individual and environmental factors including exposed body surface area (BSA), UVB dose and vitamin D status, on serum 25(OH)D concentration. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses, and Meta-analysis of Observational studies in Epidemiology guidelines, a systematic literature search was conducted (MEDLINE; 01/1960-07/2016) investigating the impact of these factors on vitamin D status after artificial UV exposure as main outcome measure. Summary mean differences [and 95% confidence interval (CI)] were derived from random-effects meta-analysis to account for possible heterogeneity across studies. Meta-regression was conducted to account for impact of UVB dose, baseline 25(OH)D level and BSA. We identified 15 studies, with an estimated mean 25(OH)D rise per standard erythema dose (SED) of 0.19 nmol/l (95% CI 0.11-0.26 nmol/l). Results from meta-regression suggest a significant impact of UV dose and baseline 25(OH)D concentration on serum 25(OH)D level (p<0.01). Single UVB doses between 0.75 and 3 SED resulted in the highest rise of serum 25(OH)D per dose unit. BSA exposed had a smaller, non-proportional, not significant impact. Partial BSA exposure resulted in relatively higher rise compared to whole-body exposure (e.g. exposure of face and hands caused an 8-fold higher rise of serum 25(OH)D concentration/SED/1% BSA compared to whole-body exposure). Our findings support previous reports, estimating that the half-life of serum 25(OH)D varies depending on different factors. Our results indicate that partial BSA exposure (e.g. 10%) with moderate UV doses (e.g. 1 SED) is effective in generating or maintaining a healthy vitamin D status. However, due to limitations that include possible

  2. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    Central Florida, Orlando, in March 2010. Several speakers at this meeting were invited to contribute to the special section in this issue. As is clear from the articles in this special section, the phenomenon of vibrations at surfaces continues to be a dynamic field of investigation. In fact, there is a resurgence of effort because the insights provided by surface dynamics are still fundamental to the development of an understanding of the microscopic factors that control surface structure formation, diffusion, reaction and structural stability. Examination of dynamics at surfaces thus complements and supplements the wealth of information that is obtained from real-space techniques such as scanning tunneling microscopy. Vibrational dynamics is, of course, not limited to surfaces. Surfaces are important since they provide immediate deviation from the bulk. They display how lack of symmetry can lead to new structures, new local atomic environments and new types of dynamical modes. Nanoparticles, large molecules and nanostructures of all types, in all kinds of local environments, provide further examples of regions of reduced symmetry and coordination, and hence display characteristic vibrational modes. Given the tremendous advance in the synthesis of a variety of nanostructures whose functionalization would pave the way for nanotechnology, there is even greater need to engage in experimental and theoretical techniques that help extract their vibrational dynamics. Such knowledge would enable a more complete understanding and characterization of these nanoscale systems than would otherwise be the case. The papers presented here provide excellent examples of the kind of information that is revealed by vibrations at surfaces. Vibrations at surface contents Poisoning and non-poisoning oxygen on Cu(410)L Vattuone, V Venugopal, T Kravchuk, M Smerieri, L Savio and M Rocca Modifying protein adsorption by layers of glutathione pre-adsorbed on Au(111)Anne Vallée, Vincent Humblot

  3. Convex surfaces

    CERN Document Server

    Busemann, Herbert

    2008-01-01

    This exploration of convex surfaces focuses on extrinsic geometry and applications of the Brunn-Minkowski theory. It also examines intrinsic geometry and the realization of intrinsic metrics. 1958 edition.

  4. Surface boxplots

    KAUST Repository

    Genton, Marc G.

    2014-01-22

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  5. Surface boxplots

    KAUST Repository

    Genton, Marc G.; Johnson, Christopher; Potter, Kristin; Stenchikov, Georgiy L.; Sun, Ying

    2014-01-01

    In this paper, we introduce a surface boxplot as a tool for visualization and exploratory analysis of samples of images. First, we use the notion of volume depth to order the images viewed as surfaces. In particular, we define the median image. We use an exact and fast algorithm for the ranking of the images. This allows us to detect potential outlying images that often contain interesting features not present in most of the images. Second, we build a graphical tool to visualize the surface boxplot and its various characteristics. A graph and histogram of the volume depth values allow us to identify images of interest. The code is available in the supporting information of this paper. We apply our surface boxplot to a sample of brain images and to a sample of climate model outputs.

  6. Surface channeling

    International Nuclear Information System (INIS)

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  7. Martian surface

    International Nuclear Information System (INIS)

    Carr, M.H.

    1987-01-01

    The surface of Mars is characterized on the basis of reformatted Viking remote-sensing data, summarizing results published during the period 1983-1986. Topics examined include impact craters, ridges and faults, volcanic studies (modeling of surface effects on volcanic activity, description and interpretation of volcanic features, and calculations on lava-ice interactions), the role of liquid water on Mars, evidence for abundant ground ice at high latitudes, water-cycle modeling, and the composition and dynamics of Martian dust

  8. Surface decontamination

    International Nuclear Information System (INIS)

    Silva, S. da; Teixeira, M.V.

    1986-06-01

    The general methods of surface decontamination used in laboratory and others nuclear installations areas, as well as the procedures for handling radioactive materials and surfaces of work are presented. Some methods for decontamination of body external parts are mentioned. The medical supervision and assistance are required for internal or external contamination involving or not lesion in persons. From this medical radiation protection decontamination procedures are determined. (M.C.K.) [pt

  9. Surface phonons

    CERN Document Server

    Wette, Frederik

    1991-01-01

    In recent years substantial progress has been made in the detection of surface phonons owing to considerable improvements in inelastic rare gas scattering tech­ niques and electron energy loss spectroscopy. With these methods it has become possible to measure surface vibrations in a wide energy range for all wave vectors in the two-dimensional Brillouin zone and thus to deduce the complete surface phonon dispersion curves. Inelastic atomic beam scattering and electron energy loss spectroscopy have started to play a role in the study of surface phonons similar to the one played by inelastic neutron scattering in the investigation of bulk phonons in the last thirty years. Detailed comparison between experimen­ tal results and theoretical studies of inelastic surface scattering and of surface phonons has now become feasible. It is therefore possible to test and to improve the details of interaction models which have been worked out theoretically in the last few decades. At this point we felt that a concise, co...

  10. Mapping of monoclonal antibody- and receptor-binding domains on human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) using a surface plasmon resonance-based biosensor.

    Science.gov (United States)

    Laricchia-Robbio, L; Liedberg, B; Platou-Vikinge, T; Rovero, P; Beffy, P; Revoltella, R P

    1996-10-01

    An automated surface plasmon resonance (SPR)-based biosensor system has been used for mapping antibody and receptor-binding regions on the recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) molecule. A rabbit antimouse IgG1-Fc antibody (RAM.Fc) was coupled to an extended carboxymethylated-hydrogel matrix attached to a gold surface in order to capture an anti-rhGM-CSF monoclonal antibody (MAb) injected over the sensing layer. rhGM-CSF was subsequently injected and allowed to bind to this antibody. Multisite binding assays were then performed, by flowing sequentially other antibodies and peptides over the surface, and the capacity of the latter to interact with the entrapped rhGM-CSF in a multimolecular complex was monitored in real time with SPR. Eleven MAb (all IgG1K), were analyzed: respectively, four antipeptide MAb raised against three distinct epitopes of the cytokine (two clones against residues 14-24, that includes part of the first alpha-helix toward the N-terminal region; one clone against peptide 30-41, an intrahelical loop; and one clone against residues 79-91, including part of the third alpha-helix) and seven antiprotein MAbs raised against the entire rhGM-CSF, whose target native epitopes are still undetermined. In addition, the binding capacity to rhGM-CSF of a synthetic peptide, corresponding to residues 238-254 of the extracellular human GM-CSF receptor alpha-chain, endowed with rhGM-CSF binding activity, was tested. The results from experiments performed with the biosensor were compared with those obtained by a sandwich enzyme-linked immunosorbent assay (ELISA), using the same reagents. The features of the biosensor technology (fully automated, measure in real time, sharpened yes/no response, less background disturbances, no need for washing step or labeling of the reagent) offered several advantages in these studies of MAb immunoreactivity and epitope mapping, giving a much better resolution and enabling more distinct

  11. Seasonal variability of iodine and selenium in surface and groundwater as a factor that may contribute to iodine isotope balance in the thyroid gland and its irradiation in case of radioiodine contamination during accidents at the NPP

    Science.gov (United States)

    Korobova, Elena; Kolmykova, Lyudmila; Ryzhenko, Boris; Berezkin, Viktor; Saraeva, Anastasia

    2016-04-01

    Radioiodine release to the environment during the accident at the Chernobyl NPP led to the increased risk of the thyroid cancer cases within the contaminated areas, the effect being aggravated in conditions of stable iodine and selenium deficiency in local food chains. Although the drinking water iodine is usually believed to contribute not more than 10% to local diet, our estimations accounting of water content in other products and several regional studies (e.g. India and Australia) proved its portion to be at least twice as much. As radioiodine isotopes are short-lived, their absorption depends greatly on stable iodine and selenium sufficiency in thyroid gland in the first few days of contamination and seasonal variation of stable iodine and selenium in local sources of drinking water may be significant as modifying the resulting thyroid irradiation in different seasons of the year. The main goal of the study was to evaluate seasonal variation of levels of iodine and selenium in natural waters of the Bryansk region as a possible factor affecting the radioiodine intake by thyroid gland of animals and humans in case of radioiodine contamination during the accident. Seasonal I and Se concentration was measured in the years of 2014 and 2015 at 14 test points characterizing surface (river and lake) and drinking groundwater. Obtained data proved considerable seasonal variation of I and Se concentration in natural waters (3,7-8,1 μg/l and 0,04-0,4 μg/l respectively) related to physico-chemical water parameters, such as pH, Eh and fluctuations in concentration of dissolved organic matter. The widest I and Se seasonal variability was observed in surface and well waters, maximum I level being found in autumn at the end of vegetation period characterized by active I leaching from the decomposed organic residues by long lasting precipitations. The content of selenium in the surface waters during summer-autumn (0,06-0,3 μg/l) was higher than in spring (0,04-0,05

  12. Surface tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Takizuka, Tomonori; Kurita, Gen-ichi; Azumi, Masafumi; Takeda, Tatsuoki

    1985-10-01

    Surface tearing modes in tokamaks are studied numerically and analytically. The eigenvalue problem is solved to obtain the growth rate and the mode structure. We investigate in detail dependences of the growth rate of the m/n = 2/1 resistive MHD modes on the safety factor at the plasma surface, current profile, wall position, and resistivity. The surface tearing mode moves the plasma surface even when the wall is close to the surface. The stability diagram for these modes is presented. (author)

  13. Surface properties of beached plastics.

    Science.gov (United States)

    Fotopoulou, Kalliopi N; Karapanagioti, Hrissi K

    2015-07-01

    Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

  14. Mostly surfaces

    CERN Document Server

    Schwartz, Richard Evan

    2011-01-01

    This book presents a number of topics related to surfaces, such as Euclidean, spherical and hyperbolic geometry, the fundamental group, universal covering surfaces, Riemannian manifolds, the Gauss-Bonnet Theorem, and the Riemann mapping theorem. The main idea is to get to some interesting mathematics without too much formality. The book also includes some material only tangentially related to surfaces, such as the Cauchy Rigidity Theorem, the Dehn Dissection Theorem, and the Banach-Tarski Theorem. The goal of the book is to present a tapestry of ideas from various areas of mathematics in a clear and rigorous yet informal and friendly way. Prerequisites include undergraduate courses in real analysis and in linear algebra, and some knowledge of complex analysis.

  15. Surface rights

    Directory of Open Access Journals (Sweden)

    Regina Célia Corrêa Landim

    2009-06-01

    Full Text Available In many cities of Brazil, social inequality is illustrated by violence, poverty, and unemployment located next to luxurious residential towers and armored passenger cars. In the face of this situation, the National Movement of Urban Reform encouraged the inclusion of the social function of property in Brazil's new constitution of 1988. Surface rights represent an urbanistic instrument in the city statute that is best aligned to the constitutional principles and urban policies. The current article compares two laws that govern the principle of surface rights and provides a brief history of the evolution of the state based on illuminism and the consequent change in paradigm affecting individual rights, including property and civil rights, and their interpretation under the Constitution. The article concludes by suggesting the use of land surface rights in a joint operation, matching the ownership of the property with urban planning policies and social interest.

  16. On the variability of plant bio-concentration factors (BCF) of environmental radionuclides. A case study on the effects of surface film and free space on the interpretation of 99mTcO4- sorption in duckweed

    International Nuclear Information System (INIS)

    Wolterbeek, H.T.; Van der Meer, A.J.G.M.; Dielemans, U.

    2000-01-01

    The present paper addresses plant bioaccumulation factor (BCF) variability, and specifically focuses attention upon the handling of duckweed (Lemna gibba) material, sampled from experimental media, especially considering accumulation/kinetic studies with 99mTcO 4 - . In these short-term studies, relatively small BCF-values may be encountered, with related interferences in its assessment due to the presence of 99mTcO 4 - in the surface film medium (SF) and in the cellular water free spaces (FS). The sample handling methods used to remove the SF+FS component of the accumulated 99mTcO 4 - consisted of blotting, centrifugation and rinsing. The three methods were investigated using d-[1- 14 C]mannitol, 42K + , 82Br - and 99mTcO 4 - radioisotopes, which were measured by - and γ-spectrometry, in both solution and solid samples. Centrifugation seems the most promising method to remove SF+FS 99mTcO 4 - . Results based on both mass analysis and radioactivity determinations in centrifugated fluids are independent of applied concentrations (10 -11 to 10 -3 mol m -3 99mTcO 4 - ), and are invariably compatible with the conceptual idea of the FS as a free-entrance phase for solutes. Blotting results in an overestimation of BCF values (up to factor 3 for the 99mTcO 4 - experiments performed), probably due to the incomplete removal of the SF+FS, and is suggested to yield irregular results, leading to high variances in BCF values obtained. The application of an efflux/rinsing period is indicated to result in an underestimation of BCF values (up to factor 10 for the 99mTcO 4 - experiments performed), probably due to excess removal of (non-SF+FS) components of accumulated solutes. Here we advocate centrifugation as a routine sample handling method to avoid SF+FS interferences in short-term (kinetic) 99mTcO 4 - uptake studies in duckweed. Moreover, the results suggest a more general applicability of centrifugation as a sample handling method to avoid SF+FS interferences in short

  17. Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China – Part 2: The roles of anthropogenic emissions and climate variability

    Directory of Open Access Journals (Sweden)

    W. Xu

    2018-01-01

    summertime ozone measured at WLG shows no significant trend despite ozone increases in eastern China. Analysis of the Trajectory-mapped Ozonesonde data set for the Stratosphere and Troposphere (TOST and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the quasi-biennial oscillation (QBO, the East Asian summer monsoon (EASM, and the sunspot cycle. Our results suggest that the 2–3-, 3–7-, and 11-year periodicities are linked to the QBO, EASM index, and sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

  18. Statistical sums of strings on hyperellyptic surfaces

    International Nuclear Information System (INIS)

    Lebedev, D.; Morozov, A.

    1987-01-01

    Contributions of hyperellyptic surfaces to statistical sums of string theories are presented. Available results on hyperellyptic surface give the apportunity to check factorization of three-loop statsum. Some remarks on the vanishing statistical sum are presented

  19. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    2010-01-01

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion...... of attack surfaces of the cloud computing scenario participants....

  20. Activation of human gingival epithelial cells by cell-surface components of black-pigmented bacteria: augmentation of production of interleukin-8, granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor and expression of intercellular adhesion molecule 1.

    Science.gov (United States)

    Sugiyama, A; Uehara, A; Iki, K; Matsushita, K; Nakamura, R; Ogawa, T; Sugawara, S; Takada, H

    2002-01-01

    Black-pigmented anaerobic bacteria, such as Porphyromonas gingivalis and Prevotella intermedia, are amongst the predominant bacteria in periodontal pockets and have been implicated in periodontal diseases. To elucidate the roles of gingival keratinocytes, which are the first cells encountered by oral bacteria in periodontal diseases, human gingival keratinocytes in primary culture were stimulated with cell-surface components of P gingivalis and Pr. intermedia. A glycoprotein fraction from Pr. intermedia (PGP) clearly augmented the release of interleukin-8, granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, as determined by enzyme-linked immunosorbent assay. This PGP also induced expression of intercellular adhesion molecule-1 (ICAM-1), as determined by flow cytometry. The augmentation of mRNA expression for these molecules was also confirmed by reverse transcription PCR. In contrast, lipopolysaccharide (LPS) from Pr. intermedia and Escherichia coli was completely inactive in these assays. LPS fraction and purified fimbriae from P gingivalis exhibited weak activities. Cytokine production and ICAM-1 expression by gingival keratinocytes might cause accumulation and activation of neutrophils in the epithelium and, therefore, may be involved in the initiation and development of inflammation in periodontal tissues.

  1. Surface smoothness

    DEFF Research Database (Denmark)

    Tummala, Sudhakar; Dam, Erik B.

    2010-01-01

    accuracy, such novel markers must therefore be validated against clinically meaningful end-goals such as the ability to allow correct diagnosis. We present a method for automatic cartilage surface smoothness quantification in the knee joint. The quantification is based on a curvature flow method used....... We demonstrate that the fully automatic markers eliminate the time required for radiologist annotations, and in addition provide a diagnostic marker superior to the evaluated semi-manual markers....

  2. Mars Surface Environmental Issues

    Science.gov (United States)

    Charles, John

    2002-01-01

    Planetary exploration by astronauts will require extended periods of habitation on a planet's surface, under the influence of environmental factors that are different from those of Earth and the spacecraft that delivered the crew to the planet. Human exploration of Mars, a possible near-term planetary objective, can be considered a challenging scenario. Mission scenarios currently under consideration call for surface habitation periods of from 1 to 18 months on even the earliest expeditions. Methods: Environmental issues associated with Mars exploration have been investigated by NASA and the National Space Biomedical Research Institute (NSBRI) as part of the Bioastronautics Critical Path Roadmap Project (see http ://criticalpath.jsc.nasa.gov). Results: Arrival on Mars will immediately expose the crew to gravity only 38% of that at Earth's surface in possibly the first prolonged exposure to gravity other than the 1G of Earth's surface and the zero G of weightless space flight, with yet unknown effects on crew physiology. The radiation at Mars' surface is not well documented, although the planet's bulk and even its thin atmosphere may moderate the influx of galactic cosmic radiation and energetic protons from solar flares. Secondary radiation from activated components of the soil must also be considered. Ultrafine and larger respirable and nonrespirable particles in Martian dust introduced into the habitat after surface excursions may induce pulmonary inflammation exacerbated by the additive reactive and oxidizing nature of the dust. Stringent decontamination cannot eliminate mechanical and corrosive effects of the dust on pressure suits and exposed machinery. The biohazard potential of putative indigenous Martian microorganisms may be assessed by comparison with analog environments on Earth. Even in their absence, human microorganisms, if not properly controlled, can be a threat to the crew's health. Conclusions: Mars' surface offers a substantial challenge to the

  3. The surface learned from nature

    Science.gov (United States)

    Lim, H.; Kim, W. D.

    2010-07-01

    In this work, I would like to introduce the emerging surface of nature. The surface in nature, has the multi and optimized function with well organized structure. There are so many examples that we learn and apply to technology. First example is self-cleaning surface. Some plants (such as lotus leaf, taro leaf) and the wings of many large-winged insects (such as moth, butterfly, dragonfly) remain their surface clean in the very dirty environment. This self cleaning effect is accomplished by the superhydrophobic surfaces which exhibit the water contact angle of more than 150° with low sliding angle. Generally, the superhydrophobic surface is made up the two factors. One is the surface composition having the low surface tension energy. The other is the surface morphology of hierarchical structure of micro and nano size. Because almost nature surface have the hierarchical structures range from macro to nano size, their topography strength their function to adjust the life in nature environment. The other example is the surface to use for drag reduction. The skin friction drag causes eruptions of air or water resulting in greater drag as the speed is increased. This drag requires more energy to overcome. The shark skin having the fine sharp-edged grooves about 0.1 mm wide known riblet reduces in skin friction drag by being far away the vortex. Among a lot of fuctional surface, the most exciting surface the back of stenocara a kind of desert beetles. Stenocara use the micrometre-sized patterns of hydrophobic, wax-coated and hydrophilic, non-waxy regions on their backs to capture water from fog. This fog-collecting structure improves the water collection of fog-capture film, condenser, engine, and future building. Here, the efforts to realize these emerging functional surfaces in nature on technology are reported with the fabrication method and their properties, especially for the control of surface wettability.

  4. Superhydrophobic surfaces fabricated by surface modification of alumina particles

    Science.gov (United States)

    Richard, Edna; Aruna, S. T.; Basu, Bharathibai J.

    2012-10-01

    The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.

  5. Zinc adsorption on clays inferred from atomistic simulations and EXAFS spectroscopy

    International Nuclear Information System (INIS)

    Churakov, S.V.; Daehn, R.

    2012-01-01

    structure, compared to only 0.3 [mmol/kg] for STx-1. Compared to the foreseen added Zn loadings of ∼2 mmol/kg and ∼30 mmol/kg, respectively, the quantity of incorporated Zn in the STx-1 is quite low and thus does not impair the EXAFS signal form the adsorbed species. The molecular structure of various Zn complexes on the (010), (110), (130) and (100) edges of 2:1 di-octahedral clays were obtained from ab initio MD simulations and geometry optimization runs based on the density functional theory using the Gaussians and Augmented Plane Waves method as implemented in the CP2K simulation package (VANDEVONDELE et al., 2005). The surface complexation of Zn was modeled for both the cv- and tv-vacant clay polymorphs (TSIPURSKY and DRITS, 1984). The mechanism of Zn uptake from solution onto the edge surface was derived from ab initio MD simulations, whereas the incorporation of Zn into the clay structure was modeled either by substituting an Al octahedron with a Zn atom or by placing an extra Zn ion in a vacant octahedron of both cv- and tv- vacant clay polymorphs. Theoretical EXAFS spectra were calculated based on molecular configurations derived from ab initio simulations using the FEFF 8.40 program (ANKUDINOV et al., 1998; ANKUDINOV and REHR, 2000). A global Debye-Waller factor was used to account for structural and thermal disorder in the static configurations obtained by the geometry optimization. In MD runs the thermal disorder was taken into account by averaging the spectra from different snapshots of the MD trajectory. The analysis of the measured EXAFS spectra and simulation results suggests that Zn preferentially substitutes for Al(III) in the trans-symmetric sites of the octahedral layer (Figure 1). At low loading Zn is incorporated into the outermost trans-octahedra on (010) and (110) edges. At medium loading Zn forms mono- and bi-dentate inner-sphere surface complexes attached to the octahedral layer of (010) and (110) edge sites. The maximal site density of inner

  6. FACET, Radiation View Factor with Shadowing

    International Nuclear Information System (INIS)

    Shapiro, A.B.

    1988-01-01

    1 - Description of program or function: FACET calculates the radiation geometric view factor (alternatively called shape factor, angle factor, or configuration factor) between surfaces for axisymmetric, two-dimensional planar and three-dimensional geometries with interposed third surface obstructions. FACET was developed to calculate view factors as input data to finite element heat transfer analysis codes. 2 - Method of solution: Three algorithms are incorporated to integrate the view factor equation for three dimensional geometries. The algorithm used for any two surfaces depends on their geometric relationship and whether third surface obstructions exist. The three algorithms are the area integration (AI) method, the line integration method (LI), and the Mitalas and Stephenson (MS) method. The LI method is used to calculate the view factor between two disjoint surfaces. If the two surfaces have an adjoint edge, the MS method is used. The AI method is used if there is self or third surface shadowing. In two-dimensional planar geometries, the view factor between two surfaces is calculated using Hottel's cross string method. For axisymmetric geometries in the absence of shadowing, the view factor between two surfaces is calculated by view factor algebra using the view factors between parallel coaxial discs. In the presence of self or third surface shadowing, the geometry is represented in three dimensions before calculating the view factors

  7. Surfaces of Building Practice

    OpenAIRE

    Surynková, Petra

    2009-01-01

    My diploma thesis Surfaces of Building Practice deals with the basic properties of surfaces, their mathematical description, categorization, and application in technical practice. Each studied surface is defined and its process of construction and parametrical description is listed. The thesis studies selected types of surfaces in details - these surfaces include surfaces of revolution, ruled surfaces, screw surfaces, and translational surfaces. An application of each studied surfaces is show...

  8. Antibacterial Metallic Touch Surfaces

    Directory of Open Access Journals (Sweden)

    Victor M. Villapún

    2016-08-01

    Full Text Available Our aim is to present a comprehensive review of the development of modern antibacterial metallic materials as touch surfaces in healthcare settings. Initially we compare Japanese, European and US standards for the assessment of antimicrobial activity. The variations in methodologies defined in these standards are highlighted. Our review will also cover the most relevant factors that define the antimicrobial performance of metals, namely, the effect of humidity, material geometry, chemistry, physical properties and oxidation of the material. The state of the art in contact-killing materials will be described. Finally, the effect of cleaning products, including disinfectants, on the antimicrobial performance, either by direct contact or by altering the touch surface chemistry on which the microbes attach, will be discussed. We offer our outlook, identifying research areas that require further development and an overview of potential future directions of this exciting field.

  9. Evaluation of Unfixed Tritium Surface Contamination

    International Nuclear Information System (INIS)

    Postolache, C.; Matei, Lidia

    2005-01-01

    Surface unfixed radioactive contamination represents the amount of surface total radioactive contamination which can be eliminated by pure mechanical processes. This unfixed contamination represents the main risk factor for contamination of the personnel which operates in tritium laboratories. Unfixed contamination was determined using sampling smears type FPCSN-PSE-AA. Those FPCSN-PSE-AA smears are disks of expanded polystyrene which contain acrylic acid fragments superficially grafted. Sampling factor was determinated by contaminated surface wiping with moisten smears in 50 μL butylic alcohol and activity measuring at liquid scintillation measuring device. Sampling factor was determined by the ratio between measured activity and initially real conventional activity. The sampling factor was determined for Tritium Laboratory existent surfaces: stainless steel, aluminum, glass, ceramics, linoleum, washable coats, epoxy resins type ALOREX LP-52.The sampling factors and the reproducibility were determined in function of surface nature

  10. Surface Micro Topography Replication in Injection Moulding

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf; Hansen, Hans Nørgaard; Kjær, Erik Michael

    2005-01-01

    The surface micro topography of injection moulded plastic parts can be important for aesthetical and technical reasons. The quality of replication of mould surface topography onto the plastic surface depends among other factors on the process conditions. A study of this relationship has been...... carried out with rough EDM (electrical discharge machining) mould surfaces, a PS grade, and by applying established three-dimensional topography parameters. Significant quantitative relationships between process parameters and topography parameters were established. It further appeared that replication...

  11. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Feoct-O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10-7-10-5 mbar O2 in the final stage of preparation. Such straightforward preparation of a monophase termination is generally not the case for iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe1-xO. The cation deficiency results in Fe11O16 stoichiometry, which is in line with the chemical potential in ultra-high vacuum (UHV), which is close to the border between the Fe3O4 and Fe2O3 phases. The Fe3O4(111) surface is also much studied, but two different surface terminations exist close in energy and can coexist, which makes sample preparation and data interpretation somewhat tricky. Both the Fe3O4(100) and Fe3O4(111) surfaces exhibit Fe-rich terminations as the sample selvedge becomes reduced. The Fe3O4(110) surface forms a one-dimensional (1×3) reconstruction linked to nanofaceting, which exposes the more stable Fe3O4(111) surface. α-Fe2O3(0001) is the most studied haematite surface, but difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe3O4(111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe1-xO and α-Fe2O3(0001) islands

  12. Risk Factors

    Science.gov (United States)

    ... cells do not invade nearby tissues or spread. Risk Factors Key Points Factors That are Known to ... chemicals . Factors That are Known to Increase the Risk of Cancer Cigarette Smoking and Tobacco Use Tobacco ...

  13. Silicon quantum dots: surface matters

    Czech Academy of Sciences Publication Activity Database

    Dohnalová, K.; Gregorkiewicz, T.; Kůsová, Kateřina

    2014-01-01

    Roč. 26, č. 17 (2014), 1-28 ISSN 0953-8984 R&D Projects: GA ČR GPP204/12/P235 Institutional support: RVO:68378271 Keywords : silicon quantum dots * quantum dot * surface chemistry * quantum confinement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.346, year: 2014

  14. Surface excitation parameter for rough surfaces

    International Nuclear Information System (INIS)

    Da, Bo; Salma, Khanam; Ji, Hui; Mao, Shifeng; Zhang, Guanghui; Wang, Xiaoping; Ding, Zejun

    2015-01-01

    Graphical abstract: - Highlights: • Instead of providing a general mathematical model of roughness, we directly use a finite element triangle mesh method to build a fully 3D rough surface from the practical sample. • The surface plasmon excitation can be introduced to the realistic sample surface by dielectric response theory and finite element method. • We found that SEP calculated based on ideal plane surface model are still reliable for real sample surface with common roughness. - Abstract: In order to assess quantitatively the importance of surface excitation effect in surface electron spectroscopy measurement, surface excitation parameter (SEP) has been introduced to describe the surface excitation probability as an average number of surface excitations that electrons can undergo when they move through solid surface either in incoming or outgoing directions. Meanwhile, surface roughness is an inevitable issue in experiments particularly when the sample surface is cleaned with ion beam bombardment. Surface roughness alters not only the electron elastic peak intensity but also the surface excitation intensity. However, almost all of the popular theoretical models for determining SEP are based on ideal plane surface approximation. In order to figure out whether this approximation is efficient or not for SEP calculation and the scope of this assumption, we proposed a new way to determine the SEP for a rough surface by a Monte Carlo simulation of electron scattering process near to a realistic rough surface, which is modeled by a finite element analysis method according to AFM image. The elastic peak intensity is calculated for different electron incident and emission angles. Assuming surface excitations obey the Poisson distribution the SEPs corrected for surface roughness are then obtained by analyzing the elastic peak intensity for several materials and for different incident and emission angles. It is found that the surface roughness only plays an

  15. Inclusion of Solar Elevation Angle in Land Surface Albedo Parameterization Over Bare Soil Surface.

    Science.gov (United States)

    Zheng, Zhiyuan; Wei, Zhigang; Wen, Zhiping; Dong, Wenjie; Li, Zhenchao; Wen, Xiaohang; Zhu, Xian; Ji, Dong; Chen, Chen; Yan, Dongdong

    2017-12-01

    Land surface albedo is a significant parameter for maintaining a balance in surface energy. It is also an important parameter of bare soil surface albedo for developing land surface process models that accurately reflect diurnal variation characteristics and the mechanism behind the solar spectral radiation albedo on bare soil surfaces and for understanding the relationships between climate factors and spectral radiation albedo. Using a data set of field observations, we conducted experiments to analyze the variation characteristics of land surface solar spectral radiation and the corresponding albedo over a typical Gobi bare soil underlying surface and to investigate the relationships between the land surface solar spectral radiation albedo, solar elevation angle, and soil moisture. Based on both solar elevation angle and soil moisture measurements simultaneously, we propose a new two-factor parameterization scheme for spectral radiation albedo over bare soil underlying surfaces. The results of numerical simulation experiments show that the new parameterization scheme can more accurately depict the diurnal variation characteristics of bare soil surface albedo than the previous schemes. Solar elevation angle is one of the most important factors for parameterizing bare soil surface albedo and must be considered in the parameterization scheme, especially in arid and semiarid areas with low soil moisture content. This study reveals the characteristics and mechanism of the diurnal variation of bare soil surface solar spectral radiation albedo and is helpful in developing land surface process models, weather models, and climate models.

  16. Experimental and theoretical study of rotationally inelastic diffraction of H{sub 2}(D{sub 2}) from methyl-terminated Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Nihill, Kevin J.; Hund, Zachary M.; Sibener, S. J., E-mail: s-sibener@uchicago.edu [The James Franck Institute and Department of Chemistry, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637 (United States); Muzas, Alberto; Cueto, Marcos del [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Díaz, Cristina [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Frankcombe, Terry [School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra ACT 2610 (Australia); Plymale, Noah T.; Lewis, Nathan S. [Division of Chemistry and Chemical Engineering, Beckman Institute and Kavli Nanoscience Institute, California Institute of Technology, 210 Noyes Laboratory, 127-72, Pasadena, California 91125 (United States); Martín, Fernando [Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid (Spain)

    2016-08-28

    Fundamental details concerning the interaction between H{sub 2} and CH{sub 3}–Si(111) have been elucidated by the combination of diffractive scattering experiments and electronic structure and scattering calculations. Rotationally inelastic diffraction (RID) of H{sub 2} and D{sub 2} from this model hydrocarbon-decorated semiconductor interface has been confirmed for the first time via both time-of-flight and diffraction measurements, with modest j = 0 → 2 RID intensities for H{sub 2} compared to the strong RID features observed for D{sub 2} over a large range of kinematic scattering conditions along two high-symmetry azimuthal directions. The Debye-Waller model was applied to the thermal attenuation of diffraction peaks, allowing for precise determination of the RID probabilities by accounting for incoherent motion of the CH{sub 3}–Si(111) surface atoms. The probabilities of rotationally inelastic diffraction of H{sub 2} and D{sub 2} have been quantitatively evaluated as a function of beam energy and scattering angle, and have been compared with complementary electronic structure and scattering calculations to provide insight into the interaction potential between H{sub 2} (D{sub 2}) and hence the surface charge density distribution. Specifically, a six-dimensional potential energy surface (PES), describing the electronic structure of the H{sub 2}(D{sub 2})/CH{sub 3}−Si(111) system, has been computed based on interpolation of density functional theory energies. Quantum and classical dynamics simulations have allowed for an assessment of the accuracy of the PES, and subsequently for identification of the features of the PES that serve as classical turning points. A close scrutiny of the PES reveals the highly anisotropic character of the interaction potential at these turning points. This combination of experiment and theory provides new and important details about the interaction of H{sub 2} with a hybrid organic-semiconductor interface, which can be used

  17. Fast and anisotropic flexibility-rigidity index for protein flexibility and fluctuation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Opron, Kristopher [Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824 (United States); Xia, Kelin [Department of Mathematics, Michigan State University, Michigan 48824 (United States); Wei, Guo-Wei, E-mail: wei@math.msu.edu [Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824 (United States); Department of Mathematics, Michigan State University, Michigan 48824 (United States); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824 (United States)

    2014-06-21

    Protein structural fluctuation, typically measured by Debye-Waller factors, or B-factors, is a manifestation of protein flexibility, which strongly correlates to protein function. The flexibility-rigidity index (FRI) is a newly proposed method for the construction of atomic rigidity functions required in the theory of continuum elasticity with atomic rigidity, which is a new multiscale formalism for describing excessively large biomolecular systems. The FRI method analyzes protein rigidity and flexibility and is capable of predicting protein B-factors without resorting to matrix diagonalization. A fundamental assumption used in the FRI is that protein structures are uniquely determined by various internal and external interactions, while the protein functions, such as stability and flexibility, are solely determined by the structure. As such, one can predict protein flexibility without resorting to the protein interaction Hamiltonian. Consequently, bypassing the matrix diagonalization, the original FRI has a computational complexity of O(N{sup 2}). This work introduces a fast FRI (fFRI) algorithm for the flexibility analysis of large macromolecules. The proposed fFRI further reduces the computational complexity to O(N). Additionally, we propose anisotropic FRI (aFRI) algorithms for the analysis of protein collective dynamics. The aFRI algorithms permit adaptive Hessian matrices, from a completely global 3N × 3N matrix to completely local 3 × 3 matrices. These 3 × 3 matrices, despite being calculated locally, also contain non-local correlation information. Eigenvectors obtained from the proposed aFRI algorithms are able to demonstrate collective motions. Moreover, we investigate the performance of FRI by employing four families of radial basis correlation functions. Both parameter optimized and parameter-free FRI methods are explored. Furthermore, we compare the accuracy and efficiency of FRI with some established approaches to flexibility analysis, namely

  18. Kansei, surfaces and perception engineering

    Science.gov (United States)

    Rosen, B.-G.; Eriksson, L.; Bergman, M.

    2016-09-01

    The aesthetic and pleasing properties of a product are important and add significantly to the meaning and relevance of a product. Customer sensation and perception are largely about psychological factors. There has been a strong industrial and academic need and interest for methods and tools to quantify and link product properties to the human response but a lack of studies of the impact of surfaces. In this study, affective surface engineering is used to illustrate and model the link between customer expectations and perception to controllable product surface properties. The results highlight the use of the soft metrology concept for linking physical and human factors contributing to the perception of products. Examples of surface applications of the Kansei methodology are presented from sauna bath, health care, architectural and hygiene tissue application areas to illustrate, discuss and confirm the strength of the methodology. In the conclusions of the study, future research in soft metrology is proposed to allow understanding and modelling of product perception and sensations in combination with a development of the Kansei surface engineering methodology and software tools.

  19. Calibration of alpha surface contamination monitor

    International Nuclear Information System (INIS)

    Freitas, I.S.M. de; Goncalez, O.L.

    1990-01-01

    In this work, the results, as well as the methodology, of the calibration of an alpha surface contamination monitor are presented. The calibration factors are obtained by least-squares fitting with effective variance. (author)

  20. Investigation on Surface Roughness in Cylindrical Grinding

    Science.gov (United States)

    Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar

    2011-01-01

    Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.

  1. Aims and accomplishments of surface theory

    International Nuclear Information System (INIS)

    Feibelman, P.J.

    1979-01-01

    The goals of surface science include the understanding of surface structure, transport and chemistry. However, present activities are mainly focussed on the most basic problem, viz., what are the constituents of a given surface and where are they located. Theorists are approaching this surface characterization problem from two sides. To make better use of the data available from the many experimental surface probes, an understanding of the force laws which govern the motion of probe-particles near surfaces is being developed, and the relation between the excitation and ground state spectra of a solid are being studied. In order to develop a predictive capability regarding surface structure, a variety of intrinsic surface properties are being studied, including the nature of bonds at transition metal surfaces, the meaning of bond locality in extended systems, and the electronic factors underlying the forces which govern surface geometry. These studies often raise technical issues such as the validity of using local exchange-correlation potentials and the applicability of cluster calculations to the analysis of extended surface situations, which, however, should not obscure the main thrust of current work - empirical and predictive surface structure determination. These points are illustrated with examples from recent research and ways in which experimental surface work might assist theoretical efforts are indicated

  2. Diffusion of particles adsorbed on reconstructive surface

    Czech Academy of Sciences Publication Activity Database

    Tarasenko A., Nataliya; Tarasenko, Alexander; Jastrabík, Lubomír

    2005-01-01

    Roč. 11, č. 1 (2005), s. 485-489 ISSN 0929-5607 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z10100522 Keywords : lattice gas * surface reconstruction * surface diffusion * phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.323, year: 2005

  3. Cryogenic Selective Surfaces

    Data.gov (United States)

    National Aeronautics and Space Administration — Selective surfaces have wavelength dependent emissivity/absorption. These surfaces can be designed to reflect solar radiation, while maximizing infrared emittance,...

  4. Characterization of solid surfaces

    National Research Council Canada - National Science Library

    Kane, Philip F; Larrabee, Graydon B

    1974-01-01

    .... A comprehensive review of surface analysis, this important volume surveys both principles and techniques of surface characterization, describes instrumentation, and suggests the course of future research...

  5. Factor XII (Hageman factor) deficiency

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000545.htm Factor XII (Hageman factor) deficiency To use the sharing features on this ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  6. Open algebraic surfaces

    CERN Document Server

    Miyanishi, Masayoshi

    2000-01-01

    Open algebraic surfaces are a synonym for algebraic surfaces that are not necessarily complete. An open algebraic surface is understood as a Zariski open set of a projective algebraic surface. There is a long history of research on projective algebraic surfaces, and there exists a beautiful Enriques-Kodaira classification of such surfaces. The research accumulated by Ramanujan, Abhyankar, Moh, and Nagata and others has established a classification theory of open algebraic surfaces comparable to the Enriques-Kodaira theory. This research provides powerful methods to study the geometry and topology of open algebraic surfaces. The theory of open algebraic surfaces is applicable not only to algebraic geometry, but also to other fields, such as commutative algebra, invariant theory, and singularities. This book contains a comprehensive account of the theory of open algebraic surfaces, as well as several applications, in particular to the study of affine surfaces. Prerequisite to understanding the text is a basic b...

  7. Model Correction Factor Method

    DEFF Research Database (Denmark)

    Christensen, Claus; Randrup-Thomsen, Søren; Morsing Johannesen, Johannes

    1997-01-01

    The model correction factor method is proposed as an alternative to traditional polynomial based response surface techniques in structural reliability considering a computationally time consuming limit state procedure as a 'black box'. The class of polynomial functions is replaced by a limit...... of the model correction factor method, is that in simpler form not using gradient information on the original limit state function or only using this information once, a drastic reduction of the number of limit state evaluation is obtained together with good approximations on the reliability. Methods...

  8. The Extracellular Protein Factor Epf from Streptococcus pyogenes Is a Cell Surface Adhesin That Binds to Cells through an N-terminal Domain Containing a Carbohydrate-binding Module*

    Science.gov (United States)

    Linke, Christian; Siemens, Nikolai; Oehmcke, Sonja; Radjainia, Mazdak; Law, Ruby H. P.; Whisstock, James C.; Baker, Edward N.; Kreikemeyer, Bernd

    2012-01-01

    Streptococcus pyogenes is an exclusively human pathogen. Streptococcal attachment to and entry into epithelial cells is a prerequisite for a successful infection of the human host and requires adhesins. Here, we demonstrate that the multidomain protein Epf from S. pyogenes serotype M49 is a streptococcal adhesin. An epf-deficient mutant showed significantly decreased adhesion to and internalization into human keratinocytes. Cell adhesion is mediated by the N-terminal domain of Epf (EpfN) and increased by the human plasma protein plasminogen. The crystal structure of EpfN, solved at 1.6 Å resolution, shows that it consists of two subdomains: a carbohydrate-binding module and a fibronectin type III domain. Both fold types commonly participate in ligand receptor and protein-protein interactions. EpfN is followed by 18 repeats of a domain classified as DUF1542 (domain of unknown function 1542) and a C-terminal cell wall sorting signal. The DUF1542 repeats are not involved in adhesion, but biophysical studies show they are predominantly α-helical and form a fiber-like stalk of tandem DUF1542 domains. Epf thus conforms with the widespread family of adhesins known as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), in which a cell wall-attached stalk enables long range interactions via its adhesive N-terminal domain. PMID:22977243

  9. The extracellular protein factor Epf from Streptococcus pyogenes is a cell surface adhesin that binds to cells through an N-terminal domain containing a carbohydrate-binding module.

    Science.gov (United States)

    Linke, Christian; Siemens, Nikolai; Oehmcke, Sonja; Radjainia, Mazdak; Law, Ruby H P; Whisstock, James C; Baker, Edward N; Kreikemeyer, Bernd

    2012-11-02

    Streptococcus pyogenes is an exclusively human pathogen. Streptococcal attachment to and entry into epithelial cells is a prerequisite for a successful infection of the human host and requires adhesins. Here, we demonstrate that the multidomain protein Epf from S. pyogenes serotype M49 is a streptococcal adhesin. An epf-deficient mutant showed significantly decreased adhesion to and internalization into human keratinocytes. Cell adhesion is mediated by the N-terminal domain of Epf (EpfN) and increased by the human plasma protein plasminogen. The crystal structure of EpfN, solved at 1.6 Å resolution, shows that it consists of two subdomains: a carbohydrate-binding module and a fibronectin type III domain. Both fold types commonly participate in ligand receptor and protein-protein interactions. EpfN is followed by 18 repeats of a domain classified as DUF1542 (domain of unknown function 1542) and a C-terminal cell wall sorting signal. The DUF1542 repeats are not involved in adhesion, but biophysical studies show they are predominantly α-helical and form a fiber-like stalk of tandem DUF1542 domains. Epf thus conforms with the widespread family of adhesins known as MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), in which a cell wall-attached stalk enables long range interactions via its adhesive N-terminal domain.

  10. Surfaces with Natural Ridges

    DEFF Research Database (Denmark)

    Brander, David; Markvorsen, Steen

    2015-01-01

    We discuss surfaces with singularities, both in mathematics and in the real world. For many types of mathematical surface, singularities are natural and can be regarded as part of the surface. The most emblematic example is that of surfaces of constant negative Gauss curvature, all of which...

  11. Approximation by Cylinder Surfaces

    DEFF Research Database (Denmark)

    Randrup, Thomas

    1997-01-01

    We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...

  12. Ruled Laguerre minimal surfaces

    KAUST Repository

    Skopenkov, Mikhail; Pottmann, Helmut; Grohs, Philipp

    2011-01-01

    A Laguerre minimal surface is an immersed surface in ℝ 3 being an extremal of the functional ∫ (H 2/K-1)dA. In the present paper, we prove that the only ruled Laguerre minimal surfaces are up to isometry the surfaces ℝ (φλ) = (Aφ, Bφ, Cφ + D cos 2φ

  13. Surface and body waves from surface and underground explosions

    International Nuclear Information System (INIS)

    Kusubov, A.S.

    1976-06-01

    The characteristics of surface and ground waves were recorded for surface and underground explosions up to 100 tons and 40 kt in magnitude, respectively, and a preliminary analysis of these results is presented. The experiments were conducted at NTS in the Yucca Flats, Nevada. Ground motions were detected with triaxial geophones along seismic lines extending up to 16 miles from the point of explosions. A comparison of Rayleigh waves generated by surface and underground explosions in the same lake bed is presented indicating a very different behavior of surface and ground waves from the two types of explosions. The magnitude of the transverse wave for surface shots was smaller by a factor of two than its longitudinal counterpart. The dependence of apparent periods on the blast energy was not apparent at a fixed distance from the explosions. Changes in the apparent period with distance for both types of explosion are compared indicating a strong layering effect of the lake bed. The ground motion study was complimented by excavation of cavities generated by the explosions

  14. Mode coupling theory for nonequilibrium glassy dynamics of thermal self-propelled particles.

    Science.gov (United States)

    Feng, Mengkai; Hou, Zhonghuai

    2017-06-28

    We present a mode coupling theory study for the relaxation and glassy dynamics of a system of strongly interacting self-propelled particles, wherein the self-propulsion force is described by Ornstein-Uhlenbeck colored noise and thermal noises are included. Our starting point is an effective Smoluchowski equation governing the distribution function of particle positions, from which we derive a memory function equation for the time dependence of density fluctuations in nonequilibrium steady states. With the basic assumption of the absence of macroscopic currents and standard mode coupling approximation, we can obtain expressions for the irreducible memory function and other relevant dynamic terms, wherein the nonequilibrium character of the active system is manifested through an averaged diffusion coefficient D[combining macron] and a nontrivial structural function S 2 (q) with q being the magnitude of wave vector q. D[combining macron] and S 2 (q) enter the frequency term and the vertex term for the memory function, and thus influence both the short time and the long time dynamics of the system. With these equations obtained, we study the glassy dynamics of this thermal self-propelled particle system by investigating the Debye-Waller factor f q and relaxation time τ α as functions of the persistence time τ p of self-propulsion, the single particle effective temperature T eff as well as the number density ρ. Consequently, we find the critical density ρ c for given τ p shifts to larger values with increasing magnitude of propulsion force or effective temperature, in good accordance with previously reported simulation work. In addition, the theory facilitates us to study the critical effective temperature T for fixed ρ as well as its dependence on τ p . We find that T increases with τ p and in the limit τ p → 0, it approaches the value for a simple passive Brownian system as expected. Our theory also well recovers the results for passive systems and can be

  15. Surface Topography Hinders Bacterial Surface Motility.

    Science.gov (United States)

    Chang, Yow-Ren; Weeks, Eric R; Ducker, William A

    2018-03-21

    We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower. That is, there is a threshold between 1 and 2 μm for response to the topography. Cells on the 4 μm hemispheres were more likely to travel parallel to the local crystal axis than in other directions. Cells on the 8 μm topography were less likely to travel across the crowns of the hemispheres and were also more likely to make 30°-50° turns than on flat surfaces. These results show that surface topography can act as a significant barrier to surface motility and may therefore hinder surface exploration by bacteria. Because surface exploration can be a part of the process whereby bacteria form colonies and seek nutrients, these results help to elucidate the mechanism by which surface topography hinders biofilm formation.

  16. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD

    1995-01-01

    Low surface brightness (LSB) galaxies are galaxies dominated by an exponential disc whose central surface brightness is much fainter than the value of mu(B)(0) = 21.65 +/- 0.30 mag arcsec(-2) found by Freeman. In this paper we present broadband photometry of a sample of 21 late-type LSB galaxies.

  17. Surface phonons and elastic surface waves

    Science.gov (United States)

    Büscher, H.; Klein-Heßling, W.; Ludwig, W.

    Theoretical investigations on the dynamics of the (001), (110) and (111) surfaces of some cubic metals (Ag, Cu, Ni) will be reviewed. Both, lattice dynamical and continuum theoretical results are obtained via a Green's function formalism. The main attitude of this paper is the comparison of our results with experiments and with results obtained via slab-calculations. The calculation of elastic surface waves has been performed using a modified surface-green-function-matching method. We have used two different approaches of calculation the bulk Green's function (a) using the spectral representation and (b) a method, what works on residues. The investigations are carried out using shortrange phenomenological potentials. The atomic force constants in the first surface layers are modified to describe surface phonon anomalies, observed by experiments. In the case of Ag (100) and Ag(110) we conclude that the detection of odd symmetry shear modes by Erskine et al. [1 a, b] was not very accurate.

  18. Surface phonons and elastic surface waves

    International Nuclear Information System (INIS)

    Buescher, H.; Klein-Hessling, W.; Ludwig, W.

    1993-01-01

    Theoretical investigations on the dynamics of the (001), (110) and (111) surfaces of some cubic metals (Ag, Cu, Ni) will be reviewed. Both, lattice dynamical and continuum theoretical results are obtained via a Green's function formalism. The main attitude of this paper is the comparison of our results with experiments and with results obtained via slab-calculations. The calculation of elastic surface waves has been performed using a modified surface-green-function-matching method. We have used two different approaches of calculation the bulk Green's function (a) using the spectral representation and (b) a method, what works on residues. The investigations are carried out using shortrange phenomenological potentials. The atomic force constants in the first surface layers are modified to describe surface phonon anomalies, observed by experiments. In the case of Ag(100) and Ag(110) we conclude that the detection of odd symmetry shear modes by Erskine et al. was not very accurate. (orig.)

  19. Recent progress in surface science v.2

    CERN Document Server

    Danielli, J F; Riddiford, A C

    1964-01-01

    Recent Progress in Surface Science, Volume 2 is a 10-chapter text that covers the significant advances in some aspects of surface science, including in catalysis, genetic control of cell surface, and cell membrane. The opening chapter deals with the major factors affecting adsorption at the gas-solid interface. The subsequent chapters explore the advances in understanding of heterogeneous catalysis in terms of fundamental surface processes, as well as the concept of dynamic contact angles. These topics are followed by discussions on emulsions, flotation, and the extraordinary complexity of cel

  20. Elastic interaction between surface and spherical pore

    International Nuclear Information System (INIS)

    Ganeev, G.Z.; Kadyrzhanov, K.K.; Kislitsyn, S.B.; Turkebaev, T.Eh.

    2000-01-01

    The energy of elastic interaction of a gas-filled spherical cavity with a boundary of an elastic isotropic half-space is determined. The elastic field of a system of a spherical cavity - boundary is represented as an expansion in series of potential functions. The factors of expansions are determined by boundary conditions on a free surface of an elastic half-space and on a spherical surface of a cavity with pressure of gas P. Function of a Tresca-Miesesa on a surface of elastic surface is defined additionally with purpose creep condition determination caused by gas pressure in the cavity. (author)

  1. The development of surface topography by heavy ion sputtering

    International Nuclear Information System (INIS)

    Whitton, J.L.; Carter, G.

    1981-01-01

    The results of a detailed, systematic investigation of the development of energetic argon ion bombardment induced surface features on polycrystal and single crystal copper are presented. It is shown that the crystal structure itself is the dominant factor deciding the final form of surface topography. The earlier proposed ''necessary conditions'' for development of surface topography, viz. surface impurity, asperities, growth, surface migration and redeposition are shown to be unimportant under the clean conditions of the experiments. (Auth.)

  2. Robust factorization

    DEFF Research Database (Denmark)

    Aanæs, Henrik; Fisker, Rune; Åström, Kalle

    2002-01-01

    Factorization algorithms for recovering structure and motion from an image stream have many advantages, but they usually require a set of well-tracked features. Such a set is in generally not available in practical applications. There is thus a need for making factorization algorithms deal effect...

  3. Organizational factors

    International Nuclear Information System (INIS)

    Holy, J.

    1999-12-01

    The following organizational factors are considered with respect to the human factor and operating safety of nuclear power plants: external influences; objectives and strategy; positions and ways of management; allocation of resources; working with human resources; operators' training; coordination of work; knowledge of organization and management; proceduralization of the topic; labour organizing culture; self-improvement system; and communication. (P.A.)

  4. El factoring

    Directory of Open Access Journals (Sweden)

    Alberto Rosenthal

    1988-04-01

    Full Text Available RESUMEN El artículo  presenta, una conceptualización general de lo que es el factoring, el origen del mismo, su evolución y hace una clasificación de los distintos tipos de factoring.

  5. The crystal structure of a coxsackievirus B3-RD variant and a refined 9-angstrom cryo-electron microscopy reconstruction of the virus complexed with decay-accelerating factor (DAF) provide a new footprint of DAF on the virus surface.

    Science.gov (United States)

    Yoder, Joshua D; Cifuente, Javier O; Pan, Jieyan; Bergelson, Jeffrey M; Hafenstein, Susan

    2012-12-01

    The coxsackievirus-adenovirus receptor (CAR) and decay-accelerating factor (DAF) have been identified as cellular receptors for coxsackievirus B3 (CVB3). The first described DAF-binding isolate was obtained during passage of the prototype strain, Nancy, on rhabdomyosarcoma (RD) cells, which express DAF but very little CAR. Here, the structure of the resulting variant, CVB3-RD, has been solved by X-ray crystallography to 2.74 Å, and a cryo-electron microscopy reconstruction of CVB3-RD complexed with DAF has been refined to 9.0 Å. This new high-resolution structure permits us to correct an error in our previous view of DAF-virus interactions, providing a new footprint of DAF that bridges two adjacent protomers. The contact sites between the virus and DAF clearly encompass CVB3-RD residues recently shown to be required for binding to DAF; these residues interact with DAF short consensus repeat 2 (SCR2), which is known to be essential for virus binding. Based on the new structure, the mode of the DAF interaction with CVB3 differs significantly from the mode reported previously for DAF binding to echoviruses.

  6. Impinging Water Droplets on Inclined Glass Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Armijo, Kenneth Miguel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lance, Blake [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ho, Clifford K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Multiphase computational models and tests of falling water droplets on inclined glass surfaces were developed to investigate the physics of impingement and potential of these droplets to self-clean glass surfaces for photovoltaic modules and heliostats. A multiphase volume-of-fluid model was developed in ANSYS Fluent to simulate the impinging droplets. The simulations considered different droplet sizes (1 mm and 3 mm), tilt angles (0°, 10°, and 45°), droplet velocities (1 m/s and 3 m/s), and wetting characteristics (wetting=47° contact angle and non-wetting = 93° contact angle). Results showed that the spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) decreased with increasing inclination angle due to the reduced normal force on the surface. The hydrophilic surface yielded greater spread factors than the hydrophobic surface in all cases. With regard to impact forces, the greater surface tilt angles yielded lower normal forces, but higher shear forces. Experiments showed that the experimentally observed spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) was significantly larger than the simulated spread factor. Observed spread factors were on the order of 5 - 6 for droplet velocities of ~3 m/s, whereas the simulated spread factors were on the order of 2. Droplets were observed to be mobile following impact only for the cases with 45° tilt angle, which matched the simulations. An interesting phenomenon that was observed was that shortly after being released from the nozzle, the water droplet oscillated (like a trampoline) due to the "snapback" caused by the surface tension of the water droplet being released from the nozzle. This oscillation impacted the velocity immediately after the release. Future work should evaluate the impact of parameters such as tilt angle and surface wettability on the impact of particle/soiling uptake and removal to investigate ways that

  7. The age of Titan's surface

    Science.gov (United States)

    Neish, C. D.; Lorenz, R. D.

    2010-04-01

    High-resolution images of the surface of Titan taken by the Cassini spacecraft reveal a world with an extreme paucity of impact craters. Planetary surfaces are commonly dated by dividing the number of impact craters by the estimated impactor flux, but this approach has been confounded at Titan by several difficulties. First, high-resolution imaging of the surface of Titan is far from complete (in the near-infrared as well as radar). As of December 2007, Cassini RADAR images covered only 22% of its surface. However, we can use Monte-Carlo models to explore how many craters of a given size (with large or very large craters being of particular interest) may be present in the unobserved areas. Second, literature descriptions of the crater formation rate (e.g. Korycansky and Zahnle 2005 and Artemieva and Lunine 2005) are apparently not in agreement. We discuss possible resolutions. Third, since surface modification processes are ongoing, the actual number of craters on Titan's surface remains uncertain, as craters may be eroded beyond recognition, or obscured by lakes or sand seas. In this connection, we use the Earth as an analogue. The Earth is in many ways the most "Titan-like" world in the solar system, with extensive modification by erosion, burial, tectonism, and volcanism. We compare the observed number of terrestrial craters to the expected terrestrial impactor flux to determine the crater reduction factor for a world similar to Titan. From this information, we can back out the actual number of craters on Titan's surface and estimate its crater retention age. An accurate age estimate will be critical for constraining models of Titan's formation and evolution.

  8. Computer aided surface representation

    Energy Technology Data Exchange (ETDEWEB)

    Barnhill, R E

    1987-11-01

    The aims of this research are the creation of new surface forms and the determination of geometric and physical properties of surfaces. The full sweep from constructive mathematics through the implementation of algorithms and the interactive computer graphics display of surfaces is utilized. Both three-dimensional and multi- dimensional surfaces are considered. Particular emphasis is given to the scientific computing solution of Department of Energy problems. The methods that we have developed and that we are proposing to develop allow applications such as: Producing smooth contour maps from measured data, such as weather maps. Modeling the heat distribution inside a furnace from sample measurements. Terrain modeling based on satellite pictures. The investigation of new surface forms includes the topics of triangular interpolants, multivariate interpolation, surfaces defined on surfaces and monotone and/or convex surfaces. The geometric and physical properties considered include contours, the intersection of surfaces, curvatures as a interrogation tool, and numerical integration.

  9. Mechanics of active surfaces

    Science.gov (United States)

    Salbreux, Guillaume; Jülicher, Frank

    2017-09-01

    We derive a fully covariant theory of the mechanics of active surfaces. This theory provides a framework for the study of active biological or chemical processes at surfaces, such as the cell cortex, the mechanics of epithelial tissues, or reconstituted active systems on surfaces. We introduce forces and torques acting on a surface, and derive the associated force balance conditions. We show that surfaces with in-plane rotational symmetry can have broken up-down, chiral, or planar-chiral symmetry. We discuss the rate of entropy production in the surface and write linear constitutive relations that satisfy the Onsager relations. We show that the bending modulus, the spontaneous curvature, and the surface tension of a passive surface are renormalized by active terms. Finally, we identify active terms which are not found in a passive theory and discuss examples of shape instabilities that are related to active processes in the surface.

  10. Regularity of Minimal Surfaces

    CERN Document Server

    Dierkes, Ulrich; Tromba, Anthony J; Kuster, Albrecht

    2010-01-01

    "Regularity of Minimal Surfaces" begins with a survey of minimal surfaces with free boundaries. Following this, the basic results concerning the boundary behaviour of minimal surfaces and H-surfaces with fixed or free boundaries are studied. In particular, the asymptotic expansions at interior and boundary branch points are derived, leading to general Gauss-Bonnet formulas. Furthermore, gradient estimates and asymptotic expansions for minimal surfaces with only piecewise smooth boundaries are obtained. One of the main features of free boundary value problems for minimal surfaces is t

  11. Advanced Surface Technology

    DEFF Research Database (Denmark)

    Møller, Per; Nielsen, Lars Pleht

    of the components. It covers everything from biocompatible surfaces of IR absorbent or reflective surfaces to surfaces with specific properties within low friction, hardness, corrosion, colors, etc. The book includes more than 400 pages detailing virtually all analysis methods for examining at surfaces.......This new significant book on advanced modern surface technology in all its variations, is aimed at both teaching at engineering schools and practical application in industry. The work covers all the significant aspects of modern surface technology and also describes how new advanced techniques make...

  12. Extremal surface barriers

    International Nuclear Information System (INIS)

    Engelhardt, Netta; Wall, Aron C.

    2014-01-01

    We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy

  13. El factoring

    Directory of Open Access Journals (Sweden)

    Alberto Rosenthal

    2015-04-01

    Full Text Available RESUMEN Se presenta la segunda parte del artículo aparecido en  el número 6 de la revista EAN. Su contenido es complementario a lo expuesto en dicho número, en está aparecen las ventajas del factoring, conveniencias, limitaciones así como la forma  de efectuar un factor en Colombia,  su necesidad, incidencia económica, etc.

  14. Induced surface stress at crystal surfaces

    International Nuclear Information System (INIS)

    Dahmen, K.

    2002-05-01

    Changes of the surfaces stress Δτ (s) can be studied by observing the bending of thin crystalline plates. With this cantilever method one can gain the induced change of surface stress Δτ (s) from the bending of plates with the help of elasticity theory. For elastic isotropic substrates the relevant relations are known. Here the relations are generalized to elastic anisotropic crystals with a C 2v - Symmetry. The equilibrium shapes of crystalline plates oriented along the (100)-, (110)-, or (111)-direction which are clamped along one edge are calculated with a numeric method under the load of a homogeneous but pure isotropic or anisotropic surface stress. The results can be displayed with the dimensionality, so that the effect of clamping can be described in a systematic way. With these tabulated values one can evaluate cantilever experiments exactly. These results are generalized to cantilever methods for determining magnetoelastic constants. It is shown which magnetoelastic constants are measured in domains of thin films with ordered structures. The eigenshape and the eigenfrequency of plates constraint through a clamping at one side are calculated. These results give a deeper understanding of the elastic anisotropy. The induced surface stress of oxygen on the (110)-surface of molybdenum is measured along the principle directions Δτ [001] and Δτ [ anti 110] . The anisotropy of the surface stress is found for the p(2 x 2)-reconstruction. Lithium induces a tensile surface stress on the Molybdenum (110)-surface up to a coverage of Θ = 0, 3 monolayer. For a higher coverage the induced stress drops and reaches a level of less than -1, 2 N/m at one monolayer. It is shown, that cobalt induces a linear increasing stress with respect to the coverage on the (100)-surface of copper with a value of 2, 4GPa. The copper (100)-surface is bombarded with accelerated ions in the range between 800-2200 eV. The resulting induced compressive stress (Δτ (s) < 0) of the order

  15. Tuning the surface potential of Ag surfaces by chemisorption of oppositely-oriented thiolated carborane dipoles

    Czech Academy of Sciences Publication Activity Database

    Lübben, J.F.; Baše, Tomáš; Rupper, P.; Künniger, T.; Macháček, Jan; Guimond, S.

    2011-01-01

    Roč. 354, č. 1 (2011), s. 168-174 ISSN 0021-9797 R&D Projects: GA AV ČR(CZ) IAA400320901 Keywords : Adsorption * Thiolated carboranes * Silver surface * Surface potential * X-ray photoelectron spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 3.070, year: 2011

  16. Smooth polyhedral surfaces

    KAUST Repository

    Gü nther, Felix; Jiang, Caigui; Pottmann, Helmut

    2017-01-01

    Polyhedral surfaces are fundamental objects in architectural geometry and industrial design. Whereas closeness of a given mesh to a smooth reference surface and its suitability for numerical simulations were already studied extensively, the aim of our work is to find and to discuss suitable assessments of smoothness of polyhedral surfaces that only take the geometry of the polyhedral surface itself into account. Motivated by analogies to classical differential geometry, we propose a theory of smoothness of polyhedral surfaces including suitable notions of normal vectors, tangent planes, asymptotic directions, and parabolic curves that are invariant under projective transformations. It is remarkable that seemingly mild conditions significantly limit the shapes of faces of a smooth polyhedral surface. Besides being of theoretical interest, we believe that smoothness of polyhedral surfaces is of interest in the architectural context, where vertices and edges of polyhedral surfaces are highly visible.

  17. Surface Prognostic Charts

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface Prognostic Charts are historical surface prognostic (forecast) charts created by the United States Weather Bureau. They include fronts, isobars, cloud, and...

  18. Integrated Surface Dataset (Global)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Integrated Surface (ISD) Dataset (ISD) is composed of worldwide surface weather observations from over 35,000 stations, though the best spatial coverage is...

  19. Smooth polyhedral surfaces

    KAUST Repository

    Günther, Felix

    2017-03-15

    Polyhedral surfaces are fundamental objects in architectural geometry and industrial design. Whereas closeness of a given mesh to a smooth reference surface and its suitability for numerical simulations were already studied extensively, the aim of our work is to find and to discuss suitable assessments of smoothness of polyhedral surfaces that only take the geometry of the polyhedral surface itself into account. Motivated by analogies to classical differential geometry, we propose a theory of smoothness of polyhedral surfaces including suitable notions of normal vectors, tangent planes, asymptotic directions, and parabolic curves that are invariant under projective transformations. It is remarkable that seemingly mild conditions significantly limit the shapes of faces of a smooth polyhedral surface. Besides being of theoretical interest, we believe that smoothness of polyhedral surfaces is of interest in the architectural context, where vertices and edges of polyhedral surfaces are highly visible.

  20. Surface freezing of water

    OpenAIRE

    P?rez-D?az, J. L.; ?lvarez-Valenzuela, M. A.; Rodr?guez-Celis, F.

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered?exclusively?by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on ...

  1. Biomaterials surface science

    CERN Document Server

    Taubert, Andreas; Rodriguez-Cabello, José Carlos

    2013-01-01

    The book provides an overview of the highly interdisciplinary field of surface science in the context of biological and biomedical applications. The covered topics range from micro- and nanostructuring for imparting functionality in a top-down manner to the bottom-up fabrication of gradient surfaces by self-assembly, from interfaces between biomaterials and living matter to smart, stimuli-responsive surfaces, and from cell and surface mechanics to the elucidation of cell-chip interactions in biomedical devices.

  2. Hydrogenation of nitriles on a well-characterized nickel surface: From surface science studies to liquid phase catalytic activity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gardin, Denis Emmanuel [Univ. of California, Berkeley, CA (United States)

    1993-12-01

    Nitrile hydrogenation is the most commonly used method for preparing diverse amines. This thesis is aimed at the mechanism and factors affecting the performance of Ni-based catalysts in nitrile hydrogenations. Surface science techniques are used to study bonding of nitriles and amines to a Ni(111) surface and to identify surface intermediates. Liquid-phase hydrogenations of cyclohexene and 1-hexene on a Pt foil were carried out successfully. Finally, knowledge about the surface structure, surface chemical bond, dynamics of surface atoms (diffusion, growth), and reactivity of metal surfaces from solid-gas interface studies, is discussed.

  3. Quality factors

    International Nuclear Information System (INIS)

    Kerr, G.D.

    1986-01-01

    The quality factor, Q, is a dimensionless modifier used in converting absorbed dose, expressed in rads (or grays), to dose equivalent, expressed in rems (or seiverts). The dose equivalent is used in radiation protection to account for the biological effectiveness of different kinds of radiation. The quality factor is related to both the linear energy transfer (LET) and relative biological effectiveness (RBE). The RBE's obtained from biological experiments depend in a complex way on the observed biological effect, the specific test organism, and the experimental conditions. Judgement is involved, therefore, in the choice of the quality factor. Questions regarding the adequacy of current Q values for neutrons were raised first in a 1980 statement by the National Council on Radiation Protection (NCRP) and later in a 1985 statement by the International Commission on Radiological Protection (ICRP). In 1980, the NCRP alerted the technical community to possible future increases between a factor of three and ten in the Q for neutrons, and in 1985, the ICRP suggested an increase by a factor of two in Q for neutrons. Both the ICRP and NRCP are now recommending essentially the same guidance with regard to Q for neutrons: an increase by a factor of two. The Q for neutrons is based on a large, albeit unfocused, body of experimental data. In spite of the lack of focus, the data supporting a change in the neutron quality factor are substantial. However, the proposed doubling of Q for neutrons is clouded by other issues regarding its application. 33 refs., 4 figs., 6 tabs

  4. Decontamination of floor surfaces

    International Nuclear Information System (INIS)

    Smirous, F.

    1983-01-01

    Requirements are presented put on the surfaces of floors of radiochemical workplaces. The mechanism is described of retaining the contaminant in the surface of the flooring, ways of reducing the hazards of floor surface contamination, decontamination techniques and used decontamination agents. (J.P.)

  5. Surface vibrational spectroscopy

    International Nuclear Information System (INIS)

    Erskine, J.L.

    1984-01-01

    A brief review of recent studies which combine measurements of surface vibrational energies with lattice dynamical calculations is presented. These results suggest that surface vibrational spectroscopy offers interesting prospects for use as a molecular-level probe of surface geometry, adsorbate bond distances and molecular orientations

  6. Sulfide Mineral Surfaces

    International Nuclear Information System (INIS)

    Rosso, Kevin M.; Vaughan, David J.

    2006-01-01

    The past twenty years or so have seen dramatic development of the experimental and theoretical tools available to study the surfaces of solids at the molecular (?atomic resolution?) scale. On the experimental side, two areas of development well illustrate these advances. The first concerns the high intensity photon sources associated with synchrotron radiation; these have both greatly improved the surface sensitivity and spatial resolution of already established surface spectroscopic and diffraction methods, and enabled the development of new methods for studying surfaces. The second centers on the scanning probe microscopy (SPM) techniques initially developed in the 1980's with the first scanning tunneling microscope (STM) and atomic force microscope (AFM) experiments. The direct 'observation' of individual atoms at surfaces made possible with these methods has truly revolutionized surface science. On the theoretical side, the availability of high performance computers coupled with advances in computational modeling has provided powerful new tools to complement the advances in experiment. Particularly important have been the quantum mechanics based computational approaches such as density functional theory (DFT), which can now be easily used to calculate the equilibrium crystal structures of solids and surfaces from first principles, and to provide insights into their electronic structure. In this chapter, we review current knowledge of sulfide mineral surfaces, beginning with an overview of the principles relevant to the study of the surfaces of all crystalline solids. This includes the thermodynamics of surfaces, the atomic structure of surfaces (surface crystallography and structural stability, adjustments of atoms at the surface through relaxation or reconstruction, surface defects) and the electronic structure of surfaces. We then discuss examples where specific crystal surfaces have been studied, with the main sulfide minerals organized by structure type

  7. Sulfide Mineral Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rosso, Kevin M.; Vaughan, David J.

    2006-08-01

    The past twenty years or so have seen dramatic development of the experimental and theoretical tools available to study the surfaces of solids at the molecular (?atomic resolution?) scale. On the experimental side, two areas of development well illustrate these advances. The first concerns the high intensity photon sources associated with synchrotron radiation; these have both greatly improved the surface sensitivity and spatial resolution of already established surface spectroscopic and diffraction methods, and enabled the development of new methods for studying surfaces. The second centers on the scanning probe microscopy (SPM) techniques initially developed in the 1980's with the first scanning tunneling microscope (STM) and atomic force microscope (AFM) experiments. The direct 'observation' of individual atoms at surfaces made possible with these methods has truly revolutionized surface science. On the theoretical side, the availability of high performance computers coupled with advances in computational modeling has provided powerful new tools to complement the advances in experiment. Particularly important have been the quantum mechanics based computational approaches such as density functional theory (DFT), which can now be easily used to calculate the equilibrium crystal structures of solids and surfaces from first principles, and to provide insights into their electronic structure. In this chapter, we review current knowledge of sulfide mineral surfaces, beginning with an overview of the principles relevant to the study of the surfaces of all crystalline solids. This includes the thermodynamics of surfaces, the atomic structure of surfaces (surface crystallography and structural stability, adjustments of atoms at the surface through relaxation or reconstruction, surface defects) and the electronic structure of surfaces. We then discuss examples where specific crystal surfaces have been studied, with the main sulfide minerals organized by

  8. Status and limitations of multilayer X-ray interference structures

    International Nuclear Information System (INIS)

    Kortright, J.B.

    1996-01-01

    Trends in the performance of x-ray multilayer interference structures with periods ranging from 9 to 130 (angstrom) are reviewed. Analysis of near-normal incidence reflectance data vs photon energy reveals that the effective interface with σ in a static Debye-Waller model, describing interdiffusion and roughness, decreases as the multilayer period decreases, and reaches a lower limit of roughly 2 (angstrom). Specular reflectance and diffuse scattering from uncoated and multilayer-coated substrates having different roughness suggest that this lower limit results largely from substrate roughness. The increase in interface width with period thus results from increasing roughness of interdiffusion as the layer thickness increases

  9. Surface for dummies

    CERN Document Server

    Rathbone, Andy

    2014-01-01

    Make Microsoft's Surface work-and play-just the way you want it to Microsoft's Surface tablet has the features and personality you're looking for, with a robust environment for business computing that doesn't skimp on fun. Surface for Dummies, 2nd Edition explains how Windows 8.1 Pro and Windows RT differ, and helps you decide which Surface model is best for you. Step by step, this book walks you through both the hardware and software features of the Surface, including the touch cover and type cover, Windows RT and Windows 8.1 Pro operating systems, and the coveted Office Home & Student 2013 s

  10. Radioactive surface contamination monitors

    International Nuclear Information System (INIS)

    Aoyama, Kei; Minagoshi, Atsushi; Hasegawa, Toru

    1994-01-01

    To reduce radiation exposure and prevent contamination from spreading, each nuclear power plant has established a radiation controlled area. People and articles out of the controlled area are checked for the surface contamination of radioactive materials with surface contamination monitors. Fuji Electric has repeatedly improved these monitors on the basis of user's needs. This paper outlines typical of a surface contamination monitor, a personal surface contamination monitor, an article surface contamination monitor and a laundry monitor, and the whole-body counter of an internal contamination monitor. (author)

  11. Topological surface states on Bi$_{1-x}$Sb$_x$

    DEFF Research Database (Denmark)

    Zhu, Xie-Gang; Hofmann, Philip

    2014-01-01

    Topological insulators support metallic surface states whose existence is protected by the bulk band structure. It has been predicted early that the topology of the surface state Fermi contour should depend on several factors, such as the surface orientation and termination and this raises the qu...

  12. Global surface temperature in relation to northeast monsoon rainfall ...

    Indian Academy of Sciences (India)

    is observed that the meridional gradient in surface air temperature anomalies between Europe and ... Surface air tempera- ture is one of the factors that influence monsoon variability. The distribution of surface air temper- ature over land and sea determines the locations ..... Asia, north Indian Ocean, northeast Russia and.

  13. Laser microtexturing of implant surfaces for enhanced tissue integration

    Energy Technology Data Exchange (ETDEWEB)

    Ricci, J.L. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). Dept. of Orthodontics; Alexander, H. [Orthogen Corp., Springfield, NJ (United States)

    2001-07-01

    The success or failure of bone and soft tissue-fixed medical devices, such as dental and orthopaedic implants, depends on a complex combination of biological and mechanical factors. These factors are intimately associated with the interface between the implant surface and the surrounding tissue, and are largely determined by the composition, surface chemistry, and surface microgeometry of the implant. The relative contributions of these factors are difficult to assess. This study addresses the contribution of surface microtexture, on a controlled level, to tissue integration. (orig.)

  14. Surface freezing of water.

    Science.gov (United States)

    Pérez-Díaz, J L; Álvarez-Valenzuela, M A; Rodríguez-Celis, F

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered-exclusively-by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided.

  15. On rationally supported surfaces

    DEFF Research Database (Denmark)

    Gravesen, Jens; Juttler, B.; Sir, Z.

    2008-01-01

    We analyze the class of surfaces which are equipped with rational support functions. Any rational support function can be decomposed into a symmetric (even) and an antisymmetric (odd) part. We analyze certain geometric properties of surfaces with odd and even rational support functions....... In particular it is shown that odd rational support functions correspond to those rational surfaces which can be equipped with a linear field of normal vectors, which were discussed by Sampoli et al. (Sampoli, M.L., Peternell, M., Juttler, B., 2006. Rational surfaces with linear normals and their convolutions...... with rational surfaces. Comput. Aided Geom. Design 23, 179-192). As shown recently, this class of surfaces includes non-developable quadratic triangular Bezier surface patches (Lavicka, M., Bastl, B., 2007. Rational hypersurfaces with rational convolutions. Comput. Aided Geom. Design 24, 410426; Peternell, M...

  16. Computer aided surface representation

    Energy Technology Data Exchange (ETDEWEB)

    Barnhill, R.E.

    1990-02-19

    The central research problem of this project is the effective representation, computation, and display of surfaces interpolating to information in three or more dimensions. If the given information is located on another surface, then the problem is to construct a surface defined on a surface''. Sometimes properties of an already defined surface are desired, which is geometry processing''. Visualization of multivariate surfaces is possible by means of contouring higher dimensional surfaces. These problems and more are discussed below. The broad sweep from constructive mathematics through computational algorithms to computer graphics illustrations is utilized in this research. The breadth and depth of this research activity makes this research project unique.

  17. Pavement Aging Model by Response Surface Modeling

    Directory of Open Access Journals (Sweden)

    Manzano-Ramírez A.

    2011-10-01

    Full Text Available In this work, surface course aging was modeled by Response Surface Methodology (RSM. The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from the Ing. Antonio M. Amor refinery. Volatilized material (VM, load resistance increment (ΔL and flow resistance increment (ΔF models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (ΔL and (ΔF models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

  18. TED Study of Si(113) Surfaces

    Science.gov (United States)

    Suzuki, T.; Minoda, H.; Tanishiro, Y.; Yagi, K.

    A TED study of Si(113) surfaces was carried out. Reflections from the 3 × 2 reconstruction were seen at room temperature, while half-order reflections were very faint. The surface showed the phase transition between the 3 × 1 and the disordered (rough) structures at about 930°C. The (113) surface structure at room temperature was analyzed using TED intensity. Four kinds of structure models proposed previously, including both the 3 × 1 and the 3 × 2 reconstructed structures, were examined. The R-factors calculated using the energy-optimized atomic coordinates are not sufficiently small. After minimization of the R-factors, Dabrowski's 3 × 2 structure model is most agreeable, while Ranke's 3 × 1 and 3 × 2 structure models are not to be excluded. STM observation showed that the surface is composed of small domains of the 3 × 2 structure.

  19. Surface electrons of helium films

    International Nuclear Information System (INIS)

    Studart, N.; Hipolito, O.

    1986-01-01

    Theoretical calculations of some properties of two-dimensional electrons on a liquid helium film adsorbed on a solid substrate are reviewed. We describe the spectrum of electron bound states on bulk helium as well on helium films. The correlational properties, such as the structure factor and correlation energy, are determined as functions of the film thickness for different types of substrates in the framework of a Generalized Random-Phase Approximation. The collective excitations of this system are also described. The results for electrons on the surface of thin films and bulk helium are easily obtained. we examine the electron interaction with the excitations of the liquid helium surface resulting in a new polaron state, which was observed very recently. The ground state energy and the effective mass of this polaron are determined by using the path-integral formalism and unitary-transformation method. Recent speculations about the phase diagram of electrons on the helium film are also discussed. (Author) [pt

  20. Surface composition of Mercury from reflectance spectrophotometry

    Science.gov (United States)

    Vilas, Faith

    1988-01-01

    The controversies surrounding the existing spectra of Mercury are discussed together with the various implications for interpretations of Mercury's surface composition. Special attention is given to the basic procedure used for reducing reflectance spectrophotometry data, the factors that must be accounted for in the reduction of these data, and the methodology for defining the portion of the surface contributing the greatest amount of light to an individual spectrum. The application of these methodologies to Mercury's spectra is presented.

  1. Antifouling polymer brushes displaying antithrombogenic surface properties

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Sheikh, S.; Blaszykowski, C.; Pop-Georgievski, Ognen; Fedorov, K.; Thompson, M.; Rodriguez-Emmenegger, Cesar

    2016-01-01

    Roč. 17, č. 3 (2016), s. 1179-1185 ISSN 1525-7797 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : polymer brushes * surface characterization * antifouling surfaces Subject RIV: BO - Biophysics Impact factor: 5.246, year: 2016

  2. Risk factors for stress fractures.

    Science.gov (United States)

    Bennell, K; Matheson, G; Meeuwisse, W; Brukner, P

    1999-08-01

    Preventing stress fractures requires knowledge of the risk factors that predispose to this injury. The aetiology of stress fractures is multifactorial, but methodological limitations and expediency often lead to research study designs that evaluate individual risk factors. Intrinsic risk factors include mechanical factors such as bone density, skeletal alignment and body size and composition, physiological factors such as bone turnover rate, flexibility, and muscular strength and endurance, as well as hormonal and nutritional factors. Extrinsic risk factors include mechanical factors such as surface, footwear and external loading as well as physical training parameters. Psychological traits may also play a role in increasing stress fracture risk. Equally important to these types of analyses of individual risk factors is the integration of information to produce a composite picture of risk. The purpose of this paper is to critically appraise the existing literature by evaluating study design and quality, in order to provide a current synopsis of the known scientific information related to stress fracture risk factors. The literature is not fully complete with well conducted studies on this topic, but a great deal of information has accumulated over the past 20 years. Although stress fractures result from repeated loading, the exact contribution of training factors (volume, intensity, surface) has not been clearly established. From what we do know, menstrual disturbances, caloric restriction, lower bone density, muscle weakness and leg length differences are risk factors for stress fracture. Other time-honoured risk factors such as lower extremity alignment have not been shown to be causative even though anecdotal evidence indicates they are likely to play an important role in stress fracture pathogenesis.

  3. Fabrication of zero contact angle ultra-super hydrophilic surfaces.

    Science.gov (United States)

    Jothi Prakash, C G; Clement Raj, C; Prasanth, R

    2017-06-15

    Zero contact angle surfaces have been created with the combined effect of nanostructure and UV illumination. The contact angle of titanium surface has been optimized to 3.25°±1°. with nanotubular structures through electrochemical surface modification. The porosity and surface energy of tubular TiO 2 layer play critical role over the surface wettability and the hydrophilicity of the surface. The surface free energy has been enhanced from 23.72mJ/m 2 (bare titanium surface) to 87.11mJ/m 2 (nanotubular surface). Similar surface with TiO 2 nanoparticles coating shows superhydrophilicity with contact angle up to 5.63°±0.95°. This implies liquid imbibition and surface curvature play a crucial role in surface hydrophilicity. The contact angle has been further reduced to 0°±0.86° by illuminating the surface with UV radiation. Results shows that by tuning the nanotube morphology, highly porous surfaces can be fabricated to reduce contact angle and enhance wettability. This study provides an insight into the inter-relationship between surface structural factors and ultra-superhydrophilic surfaces which can help to optimize thermal hydraulic and self cleaning surfaces. Copyright © 2017. Published by Elsevier Inc.

  4. Surface physics theoretical models and experimental methods

    CERN Document Server

    Mamonova, Marina V; Prudnikova, I A

    2016-01-01

    The demands of production, such as thin films in microelectronics, rely on consideration of factors influencing the interaction of dissimilar materials that make contact with their surfaces. Bond formation between surface layers of dissimilar condensed solids-termed adhesion-depends on the nature of the contacting bodies. Thus, it is necessary to determine the characteristics of adhesion interaction of different materials from both applied and fundamental perspectives of surface phenomena. Given the difficulty in obtaining reliable experimental values of the adhesion strength of coatings, the theoretical approach to determining adhesion characteristics becomes more important. Surface Physics: Theoretical Models and Experimental Methods presents straightforward and efficient approaches and methods developed by the authors that enable the calculation of surface and adhesion characteristics for a wide range of materials: metals, alloys, semiconductors, and complex compounds. The authors compare results from the ...

  5. Mirror reactor surface study

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A. L.; Damm, C. C.; Futch, A. H.; Hiskes, J. R.; Meisenheimer, R. G.; Moir, R. W.; Simonen, T. C.; Stallard, B. W.; Taylor, C. E.

    1976-09-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included.

  6. Mirror reactor surface study

    International Nuclear Information System (INIS)

    Hunt, A.L.; Damm, C.C.; Futch, A.H.; Hiskes, J.R.; Meisenheimer, R.G.; Moir, R.W.; Simonen, T.C.; Stallard, B.W.; Taylor, C.E.

    1976-01-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included

  7. Ruled Laguerre minimal surfaces

    KAUST Repository

    Skopenkov, Mikhail

    2011-10-30

    A Laguerre minimal surface is an immersed surface in ℝ 3 being an extremal of the functional ∫ (H 2/K-1)dA. In the present paper, we prove that the only ruled Laguerre minimal surfaces are up to isometry the surfaces ℝ (φλ) = (Aφ, Bφ, Cφ + D cos 2φ) + λ(sin φ, cos φ, 0), where A,B,C,D ε ℝ are fixed. To achieve invariance under Laguerre transformations, we also derive all Laguerre minimal surfaces that are enveloped by a family of cones. The methodology is based on the isotropic model of Laguerre geometry. In this model a Laguerre minimal surface enveloped by a family of cones corresponds to a graph of a biharmonic function carrying a family of isotropic circles. We classify such functions by showing that the top view of the family of circles is a pencil. © 2011 Springer-Verlag.

  8. Factors Affecting Pavement Surface and Evaluation Rating Accuracy and Variability

    OpenAIRE

    Montgomery, Sharlan R; Haddock, John E

    2018-01-01

    The collection of sufficient, accurate, and consistent pavement condition data is essential to an effective pavement management system. Condition data drive a variety of pavement management tasks such as: • Predicting future pavement performance• Identifying current and future maintenance and rehabilitation needs • Estimating budget needs and requirements • Reporting to decision makers • Selecting appropriate pavement management tools Pavement condition data are represented at either th...

  9. Risk factors for hepatitis B surface antigenaemia among secondary ...

    African Journals Online (AJOL)

    2016-11-08

    Nov 8, 2016 ... 41(95.35). 2(4.65) 43 1.33. 0.26 .... of Zhang et al43 who reported a significant association between family .... ley, Borno State, Nigeria. J Com- ... vidual Differences 1990;11(6): 541. -46. 19. ... Gonzalez K, Lasko D, Bendell D.

  10. Corrosion and Biofouling of OTEC System Surfaces - Design Factors

    Science.gov (United States)

    1978-11-01

    condition between different areas on a given member can lead to accelerated attack by a differential envirornment cell . These differences can be...resistance. As shown in Figure 1, -. gal- vanic cell is essentially a battery/load system. When the intermetallic resistance, R1 , or the environmental...members of a couple should be maximized when possible. Also, insulating or high resistance F bushings, etc., can reduce or el4 !.minate galvanic corrosion

  11. Risk factors

    International Nuclear Information System (INIS)

    Dennery, M.; Dupont, M.A.

    2007-01-01

    This article deals with the development of risk management in the gas sector business: why a risk factor legal mention must precede any published financial information? Do gas companies have to face new risks? Is there specific risks bound to gas activities? Why companies want to master their risks? Is it mandatory or just a new habit? Do they expect a real benefit in return? These are the risk management questions that are analyzed in this article which is based on the public communication of 15 gas companies randomly selected over the world. The information comes from their annual reports or from documents available on their web sites. The intention of this document is not to be exhaustive or to make statistics but only to shade light on the risk factors of the gas sector. (J.S.)

  12. Water at surfaces with tunable surface chemistries

    Science.gov (United States)

    Sanders, Stephanie E.; Vanselous, Heather; Petersen, Poul B.

    2018-03-01

    Aqueous interfaces are ubiquitous in natural environments, spanning atmospheric, geological, oceanographic, and biological systems, as well as in technical applications, such as fuel cells and membrane filtration. Where liquid water terminates at a surface, an interfacial region is formed, which exhibits distinct properties from the bulk aqueous phase. The unique properties of water are governed by the hydrogen-bonded network. The chemical and physical properties of the surface dictate the boundary conditions of the bulk hydrogen-bonded network and thus the interfacial properties of the water and any molecules in that region. Understanding the properties of interfacial water requires systematically characterizing the structure and dynamics of interfacial water as a function of the surface chemistry. In this review, we focus on the use of experimental surface-specific spectroscopic methods to understand the properties of interfacial water as a function of surface chemistry. Investigations of the air-water interface, as well as efforts in tuning the properties of the air-water interface by adding solutes or surfactants, are briefly discussed. Buried aqueous interfaces can be accessed with careful selection of spectroscopic technique and sample configuration, further expanding the range of chemical environments that can be probed, including solid inorganic materials, polymers, and water immiscible liquids. Solid substrates can be finely tuned by functionalization with self-assembled monolayers, polymers, or biomolecules. These variables provide a platform for systematically tuning the chemical nature of the interface and examining the resulting water structure. Finally, time-resolved methods to probe the dynamics of interfacial water are briefly summarized before discussing the current status and future directions in studying the structure and dynamics of interfacial water.

  13. Organizational factors

    International Nuclear Information System (INIS)

    Wahlstroem, B.; Kettunen, J.

    2005-01-01

    The goal of this lecture is to give an overview of important concepts connected to organisational factors and to provide an understanding of mechanisms by which they can contribute to safe or unsafe behaviour of people. The lecture gives examples of ways to organise work, organisational deficiencies and good practices applied in safety oriented organisations. The lecture also gives an introduction to international work and Finnish national regulation connected to organisation and management. (orig.)

  14. Factor analysis

    CERN Document Server

    Gorsuch, Richard L

    2013-01-01

    Comprehensive and comprehensible, this classic covers the basic and advanced topics essential for using factor analysis as a scientific tool in psychology, education, sociology, and related areas. Emphasizing the usefulness of the techniques, it presents sufficient mathematical background for understanding and sufficient discussion of applications for effective use. This includes not only theory but also the empirical evaluations of the importance of mathematical distinctions for applied scientific analysis.

  15. Make your Boy surface

    OpenAIRE

    Ogasa, Eiji

    2013-01-01

    This is an introductory article on the Boy surface. Boy found that RP2 can be immersed into R3 and published it 1901. (The image of) the immersion is called the Boy surface after Boy's discovery. We have created a way to construct the Boy surface by using a pair of scissors, a piece of paper, and a strip of scotch tape. In this article we introduce the way.

  16. Encyclopedia of analytical surfaces

    CERN Document Server

    Krivoshapko, S N

    2015-01-01

    This encyclopedia presents an all-embracing collection of analytical surface classes. It provides concise definitions  and description for more than 500 surfaces and categorizes them in 38 classes of analytical surfaces. All classes are cross references to the original literature in an excellent bibliography. The encyclopedia is of particular interest to structural and civil engineers and serves as valuable reference for mathematicians.

  17. Hot Surface Ignition

    OpenAIRE

    Tursyn, Yerbatyr; Goyal, Vikrant; Benhidjeb-Carayon, Alicia; Simmons, Richard; Meyer, Scott; Gore, Jay P.

    2015-01-01

    Undesirable hot surface ignition of flammable liquids is one of the hazards in ground and air transportation vehicles, which primarily occurs in the engine compartment. In order to evaluate the safety and sustainability of candidate replacement fuels with respect to hot surface ignition, a baseline low lead fuel (Avgas 100 LL) and four experimental unleaded aviation fuels recommended for reciprocating aviation engines were considered. In addition, hot surface ignition properties of the gas tu...

  18. Surface science and catalysis

    International Nuclear Information System (INIS)

    Somorjai, G.A.

    1985-02-01

    Modern surface science studies have explored a large number of metal catalyst systems. Three classes of catalytic reactions can be identified: (1) those that occur over the metal surface; (2) reactions that take place on top of a strongly adsorbed overlayer and (3) reactions that occur on co-adsorbate modified surfaces. Case histories for each class are presented. 44 refs., 13 figs., 3 tabs

  19. Study the Postbuckling of Hexagonal Piezoelectric Nanowires with Surface Effect

    Directory of Open Access Journals (Sweden)

    O. Rahmani

    2014-04-01

    Full Text Available Piezoelectric nanobeams having circular, rectangular and hexagonal cross-sections are synthesized and used in various Nano structures; however, piezoelectric nanobeams with hexagonal cross-sections have not been studied in detail. In particular, the physical mechanisms of the surface effect and the role of surface stress, surface elasticity and surface piezoelectricity have not been discussed thoroughly. The present study investigated post-buckling behavior of piezoelectric nanobeams by examining surface effects. The energy method was applied to post-buckling of hexagonal nanobeams and the critical buckling voltage and amplitude are derived analytically from bulk and surface material properties and geometric factors.

  20. Surface contamination technology in decommissioning of nuclear fuel cycle

    International Nuclear Information System (INIS)

    Ishiguro, Hideharu

    2012-01-01

    Surface contamination measurement is the most basic technology in radiation control of the nuclear and radiation facilities. Loose surface contamination causes internal exposure through airborne contamination. Surface contamination measurement is recently more important in the waste management such as confirmation of decontamination factor, contamination survey of carried-out materials from radioactive control area, and application of clearance level. This report describes the base of surface contamination standards, meaning of contamination in decommissioning, relationship between clearance level and surface contamination, and current technology of surface contamination measurement. (author)

  1. Anodized dental implant surface

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Mishra

    2017-01-01

    Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  2. Surface science an introduction

    CERN Document Server

    Hudson, John

    1991-01-01

    The whole field of surface science is covered in this work. Starting with a description of the structure and thermodynamics of clean surfaces, the book goes on to discuss kinetic theory of gases and molecular beam formation. This is followed by a largesection on gas-surface interactions, and another major section on energetic particle-surface interactions. The final chapter provides the background to crystal nucleation and growth. The approach adopted is interdisciplinary and slanted towards theexperimental side, with practical analytical techniques being used to illustrate general princi

  3. Surface chemistry essentials

    CERN Document Server

    Birdi, K S

    2013-01-01

    Surface chemistry plays an important role in everyday life, as the basis for many phenomena as well as technological applications. Common examples range from soap bubbles, foam, and raindrops to cosmetics, paint, adhesives, and pharmaceuticals. Additional areas that rely on surface chemistry include modern nanotechnology, medical diagnostics, and drug delivery. There is extensive literature on this subject, but most chemistry books only devote one or two chapters to it. Surface Chemistry Essentials fills a need for a reference that brings together the fundamental aspects of surface chemistry w

  4. Sliding surface searching method for slopes containing a potential weak structural surface

    Directory of Open Access Journals (Sweden)

    Aijun Yao

    2014-06-01

    Full Text Available Weak structural surface is one of the key factors controlling the stability of slopes. The stability of rock slopes is in general concerned with set of discontinuities. However, in soft rocks, failure can occur along surfaces approaching to a circular failure surface. To better understand the position of potential sliding surface, a new method called simplex-finite stochastic tracking method is proposed. This method basically divides sliding surface into two parts: one is described by smooth curve obtained by random searching, the other one is polyline formed by the weak structural surface. Single or multiple sliding surfaces can be considered, and consequently several types of combined sliding surfaces can be simulated. The paper will adopt the arc-polyline to simulate potential sliding surface and analyze the searching process of sliding surface. Accordingly, software for slope stability analysis using this method was developed and applied in real cases. The results show that, using simplex-finite stochastic tracking method, it is possible to locate the position of a potential sliding surface in the slope.

  5. 76 FR 80448 - Quarterly Rail Cost Adjustment Factor

    Science.gov (United States)

    2011-12-23

    ... DEPARTMENT OF TRANSPORTATION Surface Transportation Board [Docket No. EP 290 (Sub-No. 5) (2012-1)] Quarterly Rail Cost Adjustment Factor AGENCY: Surface Transportation Board. ACTION: Approval of rail cost adjustment factor. SUMMARY: The Board has approved the first quarter 2012 rail cost adjustment factor (RCAF...

  6. Time dependent view factor methods

    International Nuclear Information System (INIS)

    Kirkpatrick, R.C.

    1998-03-01

    View factors have been used for treating radiation transport between opaque surfaces bounding a transparent medium for several decades. However, in recent years they have been applied to problems involving intense bursts of radiation in enclosed volumes such as in the laser fusion hohlraums. In these problems, several aspects require treatment of time dependence

  7. [Ocular surface system integrity].

    Science.gov (United States)

    Safonova, T N; Pateyuk, L S

    2015-01-01

    The interplay of different structures belonging to either the anterior segment of the eye or its accessory visual apparatus, which all share common embryological, anatomical, functional, and physiological features, is discussed. Explanation of such terms, as ocular surface, lacrimal functional unit, and ocular surface system, is provided.

  8. Pseudospherical surfaces with singularities

    DEFF Research Database (Denmark)

    Brander, David

    2017-01-01

    We study a generalization of constant Gauss curvature −1 surfaces in Euclidean 3-space, based on Lorentzian harmonic maps, that we call pseudospherical frontals. We analyse the singularities of these surfaces, dividing them into those of characteristic and non-characteristic type. We give methods...

  9. Solar absorption surface panel

    Science.gov (United States)

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  10. Random surfaces and strings

    International Nuclear Information System (INIS)

    Ambjoern, J.

    1987-08-01

    The theory of strings is the theory of random surfaces. I review the present attempts to regularize the world sheet of the string by triangulation. The corresponding statistical theory of triangulated random surfaces has a surprising rich structure, but the connection to conventional string theory seems non-trivial. (orig.)

  11. Stiction in surface micromachining

    NARCIS (Netherlands)

    Tas, Niels Roelof; Sonnenberg, A.H.; Jansen, Henricus V.; Legtenberg, R.; Legtenberg, Rob; Elwenspoek, Michael Curt

    1996-01-01

    Due to the smoothness of the surfaces in surface micromachining, large adhesion forces between fabricated structures and the substrate are encountered. Four major adhesion mechanisms have been analysed: capillary forces, hydrogen bridging, electrostatic forces and van der Waals forces. Once contact

  12. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...

  13. Bacteria-surface interactions.

    Science.gov (United States)

    Tuson, Hannah H; Weibel, Douglas B

    2013-05-14

    The interaction of bacteria with surfaces has important implications in a range of areas, including bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Many of the interactions of bacteria with surfaces produce changes in the expression of genes that influence cell morphology and behavior, including genes essential for motility and surface attachment. Despite the attention that these phenotypes have garnered, the bacterial systems used for sensing and responding to surfaces are still not well understood. An understanding of these mechanisms will guide the development of new classes of materials that inhibit and promote cell growth, and complement studies of the physiology of bacteria in contact with surfaces. Recent studies from a range of fields in science and engineering are poised to guide future investigations in this area. This review summarizes recent studies on bacteria-surface interactions, discusses mechanisms of surface sensing and consequences of cell attachment, provides an overview of surfaces that have been used in bacterial studies, and highlights unanswered questions in this field.

  14. Protective Surfacing for Playgrounds.

    Science.gov (United States)

    Frost, Joe L.

    Noting that 90 percent of serious playground injuries result from falls to hard surfaces, this paper reviews the advantages and disadvantages of various playground surfacing materials in terms of cost, climate, durability, aesthetics, and play value. Findings are based on the personal experience of the author, government documents, laboratory…

  15. Chapter 8:Surface Characterization

    Science.gov (United States)

    Mandla A. Tshabalala; Joseph Jakes; Mark R. VanLandingham; Shaoxia Wang; Jouko. Peltonen

    2013-01-01

    Surface properties of wood play an important role when wood is used or processed into different commodities such as siding, joinery, textiles, paper, sorption media, or wood composites. Thus, for example, the quality and durability of a wood coating are determined by the surface properties of the wood and the coating. The same is true for wood composites where the...

  16. Response Surface Methodology

    NARCIS (Netherlands)

    Kleijnen, Jack P.C.

    2014-01-01

    Abstract: This chapter first summarizes Response Surface Methodology (RSM), which started with Box and Wilson’s article in 1951 on RSM for real, non-simulated systems. RSM is a stepwise heuristic that uses first-order polynomials to approximate the response surface locally. An estimated polynomial

  17. Surface Loving and Surface Avoiding modes

    OpenAIRE

    Combe, Nicolas; Huntzinger, Jean Roch; Morillo, Joseph

    2008-01-01

    International audience; We theoretically study the propagation of sound waves in GaAs/AlAs superlattices focussing on periodic modes in the vicinity of the band gaps. Based on analytical and numerical calculations, we show that these modes are the product of a quickly oscillating function times a slowly varying envelope function. We carefully study the phase of the envelope function compared to the surface of a semi-infinite superlattice. Especially, the dephasing of the superlattice compared...

  18. Workbench surface editor of brain cortical surface

    Science.gov (United States)

    Dow, Douglas E.; Nowinski, Wieslaw L.; Serra, Luis

    1996-04-01

    We have developed a 3D reach-in tool to manually reconstruct 3D cortical surface patches from 2D brain atlas images. The first application of our cortex editor is building 3D functional maps, specifically Brodmann's areas. This tool may also be useful in clinical practice to adjust incorrectly mapped atlas regions due to the deforming effect of lesions. The cortex editor allows a domain expert to control the correlation of control points across slices. Correct correlation has been difficult for 3D reconstruction algorithms because the atlas slices are far apart and because of the complex topology of the cortex which differs so much from slice to slice. Also, higher precision of the resulting surfaces is demanded since these define 3D brain atlas features upon which future stereotactic surgery may be based. The cortex editor described in this paper provides a tool suitable for a domain expert to use in defining the 3D surface of a Brodmann's area.

  19. Antibacterial Au nanostructured surfaces

    Science.gov (United States)

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-01-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all

  20. Rough Surface Contact

    Directory of Open Access Journals (Sweden)

    T Nguyen

    2017-06-01

    Full Text Available This paper studies the contact of general rough curved surfaces having nearly identical geometries, assuming the contact at each differential area obeys the model proposed by Greenwood and Williamson. In order to account for the most general gross geometry, principles of differential geometry of surface are applied. This method while requires more rigorous mathematical manipulations, the fact that it preserves the original surface geometries thus makes the modeling procedure much more intuitive. For subsequent use, differential geometry of axis-symmetric surface is considered instead of general surface (although this “general case” can be done as well in Chapter 3.1. The final formulas for contact area, load, and frictional torque are derived in Chapter 3.2.