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Determination of partition behavior of organic surrogates between paperboard packaging materials and air 总被引:2,自引:0,他引:2
The suitability of recycled paperboard packaging materials for direct food contact applications is a major area of investigation. Chemical contaminants (surrogates) partitioning between recycled paper packaging and foods may affect the safety and health of the consumer. The partition behavior of all possible organic compounds between cardboards and individual foodstuffs is difficult and too time consuming for being fully investigated. Therefore it may be more efficient to determine these partition coefficients indirectly through experimental determination of the partitioning behavior between cardboard samples and air. In this work, the behavior of organic pollutants present in a set of two paper and board samples intended to be in contact with foods was studied. Adsorption isotherms have been plotted and partition coefficients between paper and air have been calculated as a basis for the estimation of their migration potential into food. Values of partition coefficients (Kpaper/air) from 47 to 1207 were obtained at different temperatures. For the less volatile surrogates such as dibutyl phthalate and methyl stearate higher Kpaper/air values were obtained. The adsorption curves showed that the more volatile substances are partitioning mainly in air phase and increasing the temperature from 70 to 100 degrees C their concentrations in air (Cair) have almost doubled. The analysis of surrogates was performed with a method based on solvent extraction and gas chromatographic-flame ionization detection (GC-FID) quantification. 相似文献
3.
Charalampides G Manoliadis O Triantafyllou A 《Isotopes in environmental and health studies》2002,38(1):15-21
The spread and variation in 206Pb/207Pb ratios make Pb isotopes a powerful tool when it comes to detecting trends in airborne particulates originating mainly from power plants. This study was conducted to determine the source of pollution in Kozani area, an affected industrial area. Lead isotopic ratios of air filters under certain meteorological conditions were compared to Pb isotope analyses sampled from lignite mines, but also to Pb isotope analyses of cultivations in soil originating from the reclamation of old abandoned lignite-mines. The particles taken into consideration have an aerodynamic diameter less than 10 microm (PM10). The measurements were carried out in a central part of the town of Kozani, West Macedonia, for one year observation period. The lead isotope values of air filters and of wheat in the Kozani area are between the values of lignite Pb and of Greek gasoline. 相似文献
4.
H. Mukundan Y. Modarres-Sadeghi J.M. Dahl F.S. Hover M.S. Triantafyllou 《Journal of Fluids and Structures》2009,25(4):617-628
Long flexible cylinders (e.g., risers, tendons and mooring lines) exposed to the marine environment encounter ocean currents leading to vortex-induced vibration (VIV). These oscillations, often driven at high frequencies over extended periods of time, may result in structural failure of the member due to fatigue damage accumulation. Recent developments in instrumentation and installation of data acquisition systems on board marine risers have made accurate measurement of riser responses possible. This paper aims at using the data from these data acquisition devices (typically strain gages and accelerometers) in order to understand the evolution of the riser VIV, with the final aim of estimating the fatigue damage. For this purpose we employ systematic techniques to reconstruct riser VIV response using the data from the available sensors. The reconstructed riser response allows estimation of the dynamic axial stresses due to bending and consequently the estimates of the fatigue damage along the entire riser. The above methods can take into account the fatigue damage arising from complicated riser motions involving the presence of traveling waves even with the use of very few sensors. An alternate approach using a Van der Pol wake oscillator model is also explored to obtain fatigue life estimates caused by riser VIV. 相似文献
5.
Vortex-induced vibration (VIV) of long flexible cylindrical structures (e.g. risers, pipelines, tendons, mooring lines) enduring ocean currents is ubiquitous in the offshore industry. Though significant effort has gone into understanding this complicated fluid–structure interaction problem, major challenges remain in modeling and predicting the response of such structures (for example a riser). The work presented in this paper provides a systematic approach to estimate and analyze the vortex-induced motions of a marine riser. A systematic framework is developed, which allows reconstruction of the riser motion from a limited number of sensors placed along its length. A full reconstruction criterion is developed, which classifies when the measurements from the sensors contain all information pertinent to riser VIV response, and when they do not, in which case additional, analytical methods must be employed. Reconstruction methods for both scenarios are developed and applied to experimental data. Finally, a systematic study on the error during the reconstruction is also undertaken. The methods developed in this paper can be applied to: improve understanding of the vortex shedding mechanisms, including the presence of traveling waves and higher-harmonic forces; develop tools for in-situ estimation of fatigue damage on marine risers; and estimate the vortex-induced forces on marine risers. 相似文献
6.
<正>Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica,along with the known 6-O-β-E -p-coumaroyl-4α-hydroxyeudesmane(1).Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane(2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesmane(3) by spectroscopic methods. 相似文献
7.
CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献
8.
M.S. Triantafyllou 《Journal of sound and vibration》1985,103(2):171-182
The dynamics of a translating catenary are studied. The static and linearized dynamic governing equations are derived along the local tangential and normal directions and it is shown that in this form two simpler equations can be derived and solved asymptotically for both small and large sag cables, horizontal or inclined. For small sag cables the solutions of one of the asymptotic equations undergo fundamental changes for specific values of the elastic stiffness, inclination angle, sag-to-span ratio and speed of translation resulting in strong mode interactions. For horizontal cables this explains the phenomena of frequency coalescence and mode reversion [1], as well as the frequency crossover and modal changes of non-translating cables [2]. For inclined cables frequency coalescence never occurs, while mode reversion is partial and strongly dependent on the inclination angle. However, in all cases of mode interaction the dynamic tension is greatly amplified. For large sag cables the solution accounts for the significant tension and curvature variation. The solution reduces to previous results for non-translating cables horizontal [3, 4] or inclined [5]. 相似文献
9.
In this paper, we present new approaches computing the rank and the null space of the (m
n + p)×(n + p) generalized Sylvester matrix of (m + 1) polynomials of maximal degrees n,p. We introduce an algorithm which handles directly a modification of the generalized Sylvester matrix, computing efficiently
its rank and null space and replacing n by log
2
n in the required complexity of the classical methods. We propose also a modification of the Gauss-Jordan factorization method
applied to the appropriately modified Sylvester matrix of two polynomials for computing simultaneously its rank and null space.
The methods can work numerically and symbolically as well and are compared in respect of their error analysis, complexity
and efficiency. Applications where the computation of the null space of the generalized Sylvester matrix is required, are
also given. 相似文献
10.
John W.Grove 《数学物理学报(B辑英文版)》2010,30(2):563-594
This article describes mathematical models for phase separated mixtures of materials that are in pressure and velocity equilibrium but not necessarily temperature equilibrium. General conditions for constitutive models for such mixtures that exhibit a single mixture sound speed are discussed and specific examples are described. 相似文献