Sample records for water absorption coefficient

  1. PURE WATER ABSORPTION COEFFICIENT AROUND 400NM: LAB MEASURED VERSUS FIELD OBSERVED

    E-print Network

    Lee, Zhongping

    PURE WATER ABSORPTION COEFFICIENT AROUND 400NM: LAB MEASURED VERSUS FIELD OBSERVED Zhongping Lee of the ratio of the backscattering coefficient to the absorption coefficient (or the sum of absorption]. In general, it has been found that reflectance can be well explained (or modeled) using known absorption

  2. Radiance irradiance inversion algorithm for estimating the absorption and backscattering coefficients of natural waters: homogeneous waters

    Microsoft Academic Search

    Howard R. Gordon; G. Chris Boynton

    1997-01-01

    A full multiple-scattering algorithm for inverting upwelling radiance ( L u ) or irradiance ( E u ) and downwelling irradiance ( E d ) profiles in homogeneous natural waters to obtain the absorption ( a ) and backscattering ( b b ) coefficients is described and tested with simulated data. An attractive feature of the algorithm is that it

  3. Determination of RW3-to-water mass-energy absorption coefficient ratio for absolute dosimetry.

    PubMed

    Seet, Katrina Y T; Hanlon, Peta M; Charles, Paul H

    2011-12-01

    The measurement of absorbed dose to water in a solid-phantom may require a conversion factor because it may not be radiologically equivalent to water. One phantom developed for the use of dosimetry is a solid water, RW3 white-polystyrene material by IBA. This has a lower mass-energy absorption coefficient than water due to high bremsstrahlung yield, which affects the accuracy of absolute dosimetry measurements. In this paper, we demonstrate the calculation of mass-energy absorption coefficient ratios, relative to water, from measurements in plastic water and RW3 with an Elekta Synergy linear accelerator (6 and 10 MV photon beams) as well as Monte Carlo modeling in BEAMnrc and DOSXYZnrc. From this, the solid-phantom-to-water correction factor was determined for plastic water and RW3. PMID:21960410

  4. Diffusion Coefficients of Water and Leachables in Methacrylate-based Crosslinked Polymers using Absorption Experiments

    PubMed Central

    Parthasarathy, Ranganathan; Misra, Anil; Park, Jonggu; Ye, Qiang; Spencer, Paulette

    2012-01-01

    The diffusion of water into dentin adhesive polymers and leaching of unpolymerized monomer from the adhesive are linked to their mechanical softening and hydrolytic degradation. Therefore, diffusion coefficient data are critical for the mechanical design of these polymeric adhesives. In this study, diffusion coefficients of water and leachables were obtained for sixteen methacrylate-based crosslinked polymers using absorption experiments. The experimental mass change data was interpreted using numerical solution of the two-dimensional diffusion equations. The calculated diffusion coefficients varied from 1.05 × 10?8 cm2/sec (co-monomer TMTMA) to 3.15 × 10?8 cm2/sec (co-monomer T4EGDMA). Correlation of the diffusion coefficients with crosslink density and hydrophilicity showed an inverse trend (R2 = 0.41). The correlation of diffusion coefficient with crosslink density and hydrophilicity are closer for molecules differing by simple repeat units (R2 = 0.95). These differences in the trends reveal mechanisms of interaction of the diffusing water with the polymer structure. PMID:22430592

  5. Absorption and backscattering coefficients and their relations to water constituents of Poyang Lake, China.

    PubMed

    Wu, Guofeng; Cui, Lijuan; Duan, Hongtao; Fei, Teng; Liu, Yaolin

    2011-12-01

    The measurement and analysis of inherent optical properties (IOPs) of the main water constituents are necessary for remote-sensing-based water quality estimation and other ecological studies of lakes. This study aimed to measure and analyze the absorption and backscattering coefficients of the main water constituents and, further, to analyze their relations to the water constituent concentrations in Poyang Lake, China. The concentrations and the absorption and backscattering coefficients of the main water constituents at 47 sampling sites were measured and analyzed as follows. (1) The concentrations of chlorophyll a (C(CHL)), dissolved organic carbon (C(DOC)), suspended particulate matter (C(SPM)), including suspended particulate inorganic matter (C(SPIM)) and suspended particulate organic matter (C(SPOM)), and the absorption coefficients of total particulate (a(p)), phytoplankton (a(ph)), nonpigment particulate (a(d)), and colored/chromophoric dissolved organic matter (a(g)) were measured in the laboratory. (2) The total backscattering coefficients, including the contribution of pure water at six wavelengths of 420, 442, 470, 510, 590, and 700 nm, were measured in the field with a HydroScat-6 backscattering sensor. (3) The backscattering coefficients without the contribution of pure water (b(b)) were then derived by subtracting the backscattering coefficients of pure water from the total backscattering coefficients. (4) The C(CHL), C(SPM), C(SPIM), C(SPOM), and C(DOC) of the 41 remaining water samples were statistically described and their correlations were analyzed. (5) The a(ph), a(d), a(p), a(g), and b(b) were visualized and analyzed, and their relations to C(CHL), C(SPM), C(SPIM), C(SPOM), or C(DOC) were studied. Results showed the following. (1) Poyang Lake was a suspended particulate inorganic matter dominant lake with low phytoplankton concentration. (2) One salient a(ph) absorption peak was found at 678 nm, and it explained 72% of the variation of C(CHL). (3) The a(d) and a(p) exponentially decreased with increasing wavelength, and they explained 74% of the variation of C(SPIM) and 71% variation of C(SPM), respectively, at a wavelength of 440 nm. (4) The a(g) also exponentially decreased with increasing wavelength, and it had no significant correlation to C(DOC) at a significance level of 0.05. (5) The b(b) decreased with increasing wavelength, and it had strong and positive correlations to C(SPM), C(SPIM) and C(SPOM), a strong and negative correlation to C(CHL), and no correlation to C(DOC) at a significance level of 0.05. Such results will be helpful for the understanding of the IOPs of Poyang Lake. They, however, only represented the IOPs during the sampling time period, and more measurements and analyses in different seasons need to be carried out in the future to ensure a comprehensive understanding of the IOPs of Poyang Lake. PMID:22192987

  6. Estimation of the absorption and backscattering coefficients from in-water radiometric measurements

    Microsoft Academic Search

    Malgorzata Stramska; Dariusz Stramski; B. Greg Mitchell; Curtis D. Mobley

    2000-01-01

    Numerical simulations of radiative transfer within the ocean surface mixed layer have been used to derive a set of simple equations for estimating the absorption, a, and backscattering, bb, coefficients in the blue-green spectral region from measurements of downwelling irradiance, Ed, upwelling irradiance, Eu, and upwelling nadir radiance, Lu. Two relationships are used in this derivation: (i) irradiance reflectance, R

  7. Modelling radiative mean absorption coefficients

    Microsoft Academic Search

    J.-F. Ripoll; B. Dubroca; G. Duffa

    2001-01-01

    We define and compute mean absorption coefficients for the macroscopic models of radiative transfer. These coefficients take into account the anisotropic form of the photon emission and lead to a better computation of a photonic flow far from the radiative equilibrium. They are deduced by averaging a specific radiative intensity on the space of frequency and are generalized versions of

  8. Converting Sabine absorption coefficients to random incidence absorption coefficients.

    PubMed

    Jeong, Cheol-Ho

    2013-06-01

    Absorption coefficients measured by the chamber method are referred to as Sabine absorption coefficients, which sometimes exceed unity due to the finite size of a sample and non-uniform intensity in the reverberation chambers under test. In this study, conversion methods from Sabine absorption coefficients to random incidence absorption coefficients are proposed. The overestimations of the Sabine absorption coefficient are investigated theoretically based on Miki's model for porous absorbers backed by a rigid wall or an air cavity, resulting in conversion factors. Additionally, three optimizations are suggested: An optimization method for the surface impedances for locally reacting absorbers, the flow resistivity for extendedly reacting absorbers, and the flow resistance for fabrics. With four porous type absorbers, the conversion methods are validated. For absorbers backed by a rigid wall, the surface impedance optimization produces the best results, while the flow resistivity optimization also yields reasonable results. The flow resistivity and flow resistance optimization for extendedly reacting absorbers are also found to be successful. However, the theoretical conversion factors based on Miki's model do not guarantee reliable estimations, particularly at frequencies below 250 Hz and beyond 2500?Hz. PMID:23742349

  9. Calculation procedure to determine average mass transfer coefficients in packed columns from experimental data for ammonia water absorption refrigeration systems

    NASA Astrophysics Data System (ADS)

    Sieres, Jaime; Fernández-Seara, José

    2008-08-01

    The ammonia purification process is critical in ammonia water absorption refrigeration systems. In this paper, a detailed and a simplified analytical model are presented to characterize the performance of the ammonia rectification process in packed columns. The detailed model is based on mass and energy balances and simultaneous heat and mass transfer equations. The simplified model is derived and compared with the detailed model. The range of applicability of the simplified model is determined. A calculation procedure based on the simplified model is developed to determine the volumetric mass transfer coefficients in the vapour phase from experimental data. Finally, the proposed model and other simple calculation methods found in the general literature are compared.

  10. Quantification of the dynamic changes in the absorption coefficient of liquid water at erbium:YAG and carbon dioxide laser wavelengths

    NASA Astrophysics Data System (ADS)

    Shori, Ramesh K.

    The interaction of high-intensity, short-pulsed radiation with liquid water results in dynamic changes in the optical absorption coefficient of water. These changes and their implications, as related to mid-infrared laser ablation of tissue, were not investigated until the late 1980's and early 1990's. Classical models of absorption and heating do not explain the dynamic, non-linear changes in water. The objective of the present work was to quantify the dynamic changes in the absorption coefficient of liquid water as a function of incident energy at three clinically relevant infrared wavelengths (? = 2.94, 9.6, 10.6 ?m). To investigate the changes in the absorption spectrum of water in the 3-?m band, a stable, high-energy Q- switched Er:YAG laser emitting 2.94-?m radiation in a near-perfect TEMoo spatial beam profile was developed. Key to the development of this laser was careful attention to the gain medium, optical pump system, system optics, and the thermal system. The final system design was capable of emitting 110 mJ/pulse at of 2-4 Hz with a lamp lifetime exceeding 12 million pulses The laser was used in two sets of experiments in order to quantify the above changes. First, the laser was used to measure the velocity of the shock front produced by vaporizing a gelatin-based tissue phantom. The measured shock velocity was related to the optical energy absorbed by the tissue phantom and the absorption coefficient, based on the pressure relationships derived using a 1-D piston model for an expanding plume. The shock front velocity measurements indicate that the absorption coefficient is constant for incident fluences less than 20 J/cm2, a result consistent with transmission data. For higher fluences, the data indicate a decrease in the absorption coefficient, which is again consistent with transmission data. Quantification of the absorption coefficient can, however, not be made without violating assumptions that form the basis for the 1-D piston model. Second, the laser was used to measure the optical transmission across water layers of known thicknesses. The data were used to develop a Dynamic Saturable Absorption (DSA) model to predict the dynamic changes in the absorption coefficient of water as a function of incident energy. The DSA model, based in part upon the homogeneous broadening of an atomic transition in a laser gain medium, accurately predicts the absorption coefficient of water over a wide range of incident fluences. One sees saturation of the absorption at both high and low fluence with a monotonic decrease in absorption with increasing fluence. Transmission measurements were also made at 9.6 and 10.6 ?m using a TEA CO2 laser. The data show essentially no change in the absorption coefficient as the fluence is varied. The results from the experiments make a significant contribution towards an understanding of the relationship among the dynamic optical properties of water and clinically relevant properties such as ablation rate and residual thermal damage.

  11. Absorption Coefficients and Impedance Daniel A. Russell

    E-print Network

    Russell, Daniel A.

    1 Absorption Coefficients and Impedance Daniel A. Russell Science and Mathematics Department will measure the absorption coefficients and acoustic impedance of samples of acoustic absorbing materials material is responsible for almost 50% of sound absorption inside an automobile). The reverberation time

  12. A Multi-Band Analytical Algorithm for Deriving Absorption and Backscattering Coefficients from Remote-Sensing Reflectance of Optically Deep Waters

    NASA Technical Reports Server (NTRS)

    Lee, Zhong-Ping; Carder, Kendall L.

    2001-01-01

    A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.

  13. Determination of absorption coefficients of thin films

    SciTech Connect

    Lodenquai, J.F. (Univ. of the West Indies, Kingston (Jamaica))

    1994-08-01

    The equations that are usually presented as those used to determine the absorption coefficients of materials in film form based on measurements of transmission and reflection coefficients are fundamentally incorrect. These equations omit a multiplicative factor arising from the complex nature of the refractive indices of the materials. This factor enters explicitly into the relationship between the transmission and reflection coefficients for such materials and is not necessarily close to unity, although in practice this factor can be approximated by unity at least in the infrared through the optical range of wavelengths.

  14. ABSORPTION DYNAMICS OF ORGANIC CHEMICAL TRANSPORT ACROSS TROUT GILLS AS RELATED TO OCTANOL-WATER PARTITION COEFFICIENT

    EPA Science Inventory

    An in vivo fish preparation was used that allowed a direct measure of the transport rates of 14 different organic chemicals across the gills of rainbow trout (Salmo gairdneri). The chemicals, all 14C labeled, were selected from five classes, encompassing a range of octanol-water ...

  15. A neural network-based four-band model for estimating the total absorption coefficients from the global oceanic and coastal waters

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Cui, Tingwei; Quan, Wenting

    2015-01-01

    this study, a neural network-based four-band model (NNFM) for the global oceanic and coastal waters has been developed in order to retrieve the total absorption coefficients a(?). The applicability of the quasi-analytical algorithm (QAA) and NNFM models is evaluated by five independent data sets. Based on the comparison of a(?) predicted by these two models with the field measurements taken from the global oceanic and coastal waters, it was found that both the QAA and NNFM models had good performances in deriving a(?), but that the NNFM model works better than the QAA model. The results of the QAA model-derived a(?), especially in highly turbid waters with strong backscattering properties of optical activity, was found to be lower than the field measurements. The QAA and NNFM models-derived a(?) could be obtained from the MODIS data after atmospheric corrections. When compared with the field measurements, the NNFM model decreased by a 0.86-24.15% uncertainty (root-mean-square relative error) of the estimation from the QAA model in deriving a(?) from the Bohai, Yellow, and East China seas. Finally, the NNFM model was applied to map the global climatological seasonal mean a(443) for the time range of July 2002 to May 2014. As expected, the a(443) value around the coastal regions was always larger than the open ocean around the equator. Viewed on a global scale, the oceans at a high latitude exhibited higher a(443) values than those at a low latitude.

  16. The spectral absorption coefficient at 254?nm as a real-time early warning proxy for detecting faecal pollution events at alpine karst water resources.

    PubMed

    Stadler, H; Klock, E; Skritek, P; Mach, R L; Zerobin, W; Farnleitner, A H

    2010-01-01

    Because spring water quality from alpine karst aquifers can change very rapidly during event situations, water abstraction management has to be performed in near real-time. Four summer events (2005-2008) at alpine karst springs were investigated in detail in order to evaluate the spectral absorption coefficient at 254?nm (SAC254) as a real-time early warning proxy for faecal pollution. For the investigation Low-Earth-Orbit (LEO) Satellite-based data communication between portable hydrometeorological measuring stations and an automated microbiological sampling device was used. The method for event triggered microbial sampling and analyzing was already established and described in a previous paper. Data analysis including on-line event characterisation (i.e. precipitation, discharge, turbidity, SAC254) and comprehensive E. coli determination (n>800) indicated that SAC254 is a useful early warning proxy. Irrespective of the studied event situations SAC254 always increased 3 to 6 hours earlier than the onset of faecal pollution, featuring different correlation phases. Furthermore, it seems also possible to use SAC254 as a real-time proxy parameter for estimating the extent of faecal pollution after establishing specific spring and event-type calibrations that take into consideration the variability of the occurrence and the transferability of faecal material It should be highlighted that diffuse faecal pollution from wildlife and live stock sources was responsible for spring water contamination at the investigated catchments. In this respect, the SAC254 can also provide useful information to support microbial source tracking efforts where different situations of infiltration have to be investigated. PMID:20962406

  17. Estimating absorption coefficients of colored dissolved organic matter (CDOM) using a semi-analytical algorithm for Southern Beaufort Sea (Canadian Arctic) waters: application to deriving concentrations of dissolved organic carbon from space

    NASA Astrophysics Data System (ADS)

    Matsuoka, A.; Hooker, S. B.; Bricaud, A.; Gentili, B.; Babin, M.

    2012-10-01

    A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for Southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows to separate colored detrital matter (CDM) into CDOM and non-algal particles (NAP) by determining NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, that were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and turbid waters, respectively. In situ measurements showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the Southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.

  18. Does the photon-diffusion coefficient depend on absorption?

    E-print Network

    Boas, David

    Does the photon-diffusion coefficient depend on absorption? T. Durduran and A. G. Yodh Department independent of absorption, i.e., D0 v/3 s . After presentation of the general theoretical arguments underlying this assertion, Monte Carlo simulations are performed and explicitly reveal that the absorption- independent

  19. The inverse bremsstrahlung absorption coefficient in collisional plasmas

    Microsoft Academic Search

    R. Cauble; W. Rozmus

    1985-01-01

    A prescription for the inverse bremsstrahlung (IB) absorption coefficient is presented. The coefficient is derived in terms of a collision frequency that is found from a memory function kinetic formalism. The formalism admits limits that allow a rigorous definition of the coefficient when the plasma is weakly coupled and approximations that provide a reliable calculation when the plasma is strongly

  20. Atmospheric absorption of terahertz radiation and water vapor continuum effects

    E-print Network

    Massachusetts at Lowell, University of

    Atmospheric absorption of terahertz radiation and water vapor continuum effects David M. Slocum a vapor Absorption Continuum Terahertz Spectroscopy a b s t r a c t The water vapor continuum absorption. The absorption coefficient as a function of frequency was determined and compared with theoretical predictions

  1. Estimating absorption coefficients of colored dissolved organic matter (CDOM) using a semi-analytical algorithm for southern Beaufort Sea waters: application to deriving concentrations of dissolved organic carbon from space

    NASA Astrophysics Data System (ADS)

    Matsuoka, A.; Hooker, S. B.; Bricaud, A.; Gentili, B.; Babin, M.

    2013-02-01

    A series of papers have suggested that freshwater discharge, including a large amount of dissolved organic matter (DOM), has increased since the middle of the 20th century. In this study, a semi-analytical algorithm for estimating light absorption coefficients of the colored fraction of DOM (CDOM) was developed for southern Beaufort Sea waters using remote sensing reflectance at six wavelengths in the visible spectral domain corresponding to MODIS ocean color sensor. This algorithm allows the separation of colored detrital matter (CDM) into CDOM and non-algal particles (NAP) through the determination of NAP absorption using an empirical relationship between NAP absorption and particle backscattering coefficients. Evaluation using independent datasets, which were not used for developing the algorithm, showed that CDOM absorption can be estimated accurately to within an uncertainty of 35% and 50% for oceanic and coastal waters, respectively. A previous paper (Matsuoka et al., 2012) showed that dissolved organic carbon (DOC) concentrations were tightly correlated with CDOM absorption in our study area (r2 = 0.97). By combining the CDOM absorption algorithm together with the DOC versus CDOM relationship, it is now possible to estimate DOC concentrations in the near-surface layer of the southern Beaufort Sea using satellite ocean color data. DOC concentrations in the surface waters were estimated using MODIS ocean color data, and the estimates showed reasonable values compared to in situ measurements. We propose a routine and near real-time method for deriving DOC concentrations from space, which may open the way to an estimate of DOC budgets for Arctic coastal waters.

  2. Energy absorption coefficients and photon kerma for LiF

    SciTech Connect

    Sharada, K.S.

    1982-01-01

    Accurate knowledge of energy absorption coefficients is needed to calculate the absorbed dose in any material. The photon kerma for LiF relative to air and soft tissue is computed using energy absorption coefficient values for Li, F, air, and tissue. Values of energy absorption coefficients for air are already available in J. H. Hubbell's (Photon Cross-Sections, Attenuation Coefficients and Energy Absorption Coefficients from 10 KeV to 100 GeV. National Standard Reference Data System-National Bureau of Standards Report No. 29, Washington, D. C., 1969) tables. Those for tissue are obtained by adding the weighted average of the energy absorption coefficients to the different elements constituting the tissue. For fluorine, they are computed from the values given by F. H. Attix and W. C. Roesche (Eds, Radiation Dosimetry, Vol. I, Fundamentals. Academic Press, New York/London, 1968) for CaF/sub 2/ and Ca. The values for lithium have been computed taking into consideration the photoelectric effect, Compton process, and pair production. Corrections for radiative energy losses, fluorescence yields, screening of electrons, etc., are appropriately applied. The energy absorption coefficients due to photoeffect, Compton scattering, and pair production are added to get the total. The energy absorption cross-section data for photon energies from 0.01 to 10 MeV are tabulated for each interaction.

  3. Measurement of Acoustic Attenuation and Absorption Coefficients using Thermometry

    NASA Astrophysics Data System (ADS)

    Morris, Hugh; Rivens, Ian; Shaw, Adam; ter Haar, Gail

    2007-05-01

    Accurate knowledge of both the attenuation and the absorption coefficient of tissue are required when planning an optimal high intensity focused ultrasound treatment. A novel technique for simple measurement of this parameters has been developed in which a thin-film thermocouple (TFT) is placed between two layers of tissue of different thicknesses. The sample can be rotated about an axis through the junction of the TFT so that it can be insonated from either side leaving the tissue adjacent to the junction unchanged, but changing the overlying thickness. The attenuation and absorption coefficients can be calculated from the heating curves measured in the two orientations. Experiments have been carried out in both tissue mimicking material (TMM) and in ex vivo liver tissue. Weakly focused transducers, resonant at 1.05 MHz, 2.4 MHz and 3.55 MHz were used at free-field spatial peak intensities of 9-14 W/cm2. The temperature rise was measured as a function of time using a TFT. These thermocouples are not subject to the viscous heating artefact that is common to other thermocouple devices and so are advantageous for this purpose. Alignment was achieved with a 3D automated gantry system, which was controlled with specialised software. Timing and data acquisition were also controlled with this software. All experiments were carried out in degassed water. Results for TMM and degassed excised bovine liver are presented.

  4. Modeling spectral diffuse attenuation, absorption, and scattering coefficients in a turbid estuary

    Microsoft Academic Search

    CHARLES L. GALLEGOS; DAVID L. CORRELL; J. W. PIERCE

    1990-01-01

    Spectral diffuse attenuation coefficients were measured in the Rhode River and Chesapeake Bay, Maryland, on 28 occasions in 1988 and 1989. The model of Kirk was used to extract scattering and absorption coefficients from the measurements in waters considerably more turbid than those in which the model was previously applied. Estimated scattering coefftcients were linearly related to mineral suspended solids.

  5. Solar thermal absorption heat pump breakeven coefficient of performance

    Microsoft Academic Search

    M. Balasubramaniam; G. L. Schrenk; A. Lowi; J. C. Denton

    1974-01-01

    This paper compares the performance of direct solar heating with heating obtained with solar energy amplified through an absorption heat pump. It is shown that if the performance of the two systems is to be at least equal under similar operating conditions, the absorption heat pump must have a minimum heating coefficient of performance (COP)H, which is defined as the

  6. Absorption cross section and absorption coefficient of the ?-? annihilation

    Microsoft Academic Search

    J. J. Ling; D. B. Liu; L. Chen

    2002-01-01

    The two-photon annihilation (?-? annihilation) is an important absorption mechanism in the theory of radiative transfer of gamma ?-ray astronomy. The expression of the annihilation cross section given by QED theory in the frame of momentum center is changed into the laboratory reference frame by the use of the skill of relativistic transformation. The new expression of cross section is

  7. Optical absorption coefficient of magneto-optic garnet films

    SciTech Connect

    Liu Gong-qiang; Yu Zhi-qiang; Liu Xianglin

    1986-02-01

    This paper analyzes various factors contributing to optical attenuation in magneto-optic garnet films and derives expressions for the optical absorption and scattering coefficients ..cap alpha.. and ..gamma... The values of ..cap alpha.. and ..gamma.. for (BiTm)/sub 3/(FeGa)/sub 5/O/sub 12/ films were measured in a magneto-optic modulation device by comparing the magneto-optic rotations. Compared with other methods, this technique has two advantages: (1) absorption in the substrate is eliminated, and the measured values ..cap alpha.. are not affected by reflection at the film/substrate interface; (2) the optical scattering coefficient ..gamma.. can be separated from the optical absorption ..cap alpha.., so that the measured value ..cap alpha.. closely approximates the true optical absorption coefficient for magneto-optic garnet film materials.

  8. The inverse bremsstrahlung absorption coefficient in collisional plasmas

    NASA Astrophysics Data System (ADS)

    Cauble, R.; Rozmus, W.

    1985-11-01

    A prescription for the inverse bremsstrahlung (IB) absorption coefficient is presented. The coefficient is derived in terms of a collision frequency that is found from a memory function kinetic formalism. The formalism admits limits that allow a rigorous definition of the coefficient when the plasma is weakly coupled and approximations that provide a reliable calculation when the plasma is strongly coupled. In the latter case, use is made of spatial distribution functions computed from the solution to the set of integral equations describing plasma correlations via the hypernetted chain approximation (HNC). A simple analytic result is compared with the HNC calculations. Results show that, as expected, the classical form for the IB absorption coefficient is of little utility when the plasma is strongly coupled. The theory presented here should provide reasonable predictions of the coefficient.

  9. Satellite retrieval of the absorption coefficient of phytoplankton phycoerythrin pigment: theory and feasibility status.

    PubMed

    Hoge, F E; Wright, C W; Lyon, P E; Swift, R N; Yungel, J K

    1999-12-20

    Oceanic radiance model inversion methods are used to develop a comprehensive algorithm for retrieval of the absorption coefficients of phycourobilin (PUB) pigment, type I phycoerythrobilin (PEB) pigment rich in PUB, and type II PEB deficient in PUB pigment (together with the usual "big three" inherent optical properties: the total backscattering coefficient and the absorption coefficients of chromophoric dissolved organic matter (CDOM)-detritus and phytoplankton). This fully modeled inversion algorithm is then simplified to yield a hybrid modeled-unmodeled inversion algorithm in which the phycoerythrin (PE) absorption coefficient is retrieved as unmodeled 488-nm absorption (which exceeds the modeled phytoplankton and the CDOM-detritus absorption coefficients). Each algorithm was applied to water-leaving radiances, but only hybrid modeled-unmodeled inversions yielded viable retrievals of the PE absorption coefficient. Validation of the PE absorption coefficient retrieval was achieved by relative comparison with airborne laser-induced PEB fluorescence. The modeled-unmodeled retrieval of four inherent optical properties by direct matrix inversion is rapid and well conditioned, but the accuracy is strongly limited by the accuracy of the three principal inherent optical property models across all four spectral bands. Several research areas are identified to enhance the radiance-model-based retrievals: (a) improved PEB and PUB absorption coefficient models, (b) PE spectral shifts induced by PUB chromophore substitution at chromophore binding sites, (c) specific absorption-sensitive phytoplankton absorption modeling, (d) total constituent backscattering modeling, (e) unmodeled carotinoid and phycocyanin absorption that are not now accounted for in the chlorophyll-dominated phytoplankton absorption coefficient model, and (f) iterative inversion techniques to solve for six constituents with only five radiances. Although considerable progress has been made toward the satellite recovery of PE absorption, the maturity of the retrieval is presently insufficient for routine global application. Instead it must currently be used on a regional basis where localized ship and aircraft validation can be made available. The algorithm was developed for the MODIS (Moderate-Resolution Imaging Spectroradiometer) sensor but is applicable to any sensor having comparable band locations. PMID:18324297

  10. Satellite Retrieval of the Absorption Coefficient of Phytoplankton Phycoerythrin Pigment: Theory and Feasibility Status

    NASA Astrophysics Data System (ADS)

    Hoge, Frank E.; Wright, C. Wayne; Lyon, Paul E.; Swift, Robert N.; Yungel, James K.

    1999-12-01

    Oceanic radiance model inversion methods are used to develop a comprehensive algorithm for retrieval of the absorption coefficients of phycourobilin (PUB) pigment, type I phycoerythrobilin (PEB) pigment rich in PUB, and type II PEB deficient in PUB pigment (together with the usual big three inherent optical properties: the total backscattering coefficient and the absorption coefficients of chromophoric dissolved organic matter (CDOM) detritus and phytoplankton). This fully modeled inversion algorithm is then simplified to yield a hybrid modeled unmodeled inversion algorithm in which the phycoerythrin (PE) absorption coefficient is retrieved as unmodeled 488-nm absorption (which exceeds the modeled phytoplankton and the CDOM detritus absorption coefficients). Each algorithm was applied to water-leaving radiances, but only hybrid modeled unmodeled inversions yielded viable retrievals of the PE absorption coefficient. Validation of the PE absorption coefficient retrieval was achieved by relative comparison with airborne laser-induced PEB fluorescence. The modeled unmodeled retrieval of four inherent optical properties by direct matrix inversion is rapid and well conditioned, but the accuracy is strongly limited by the accuracy of the three principal inherent optical property models across all four spectral bands. Several research areas are identified to enhance the radiance-model-based retrievals: (a) improved PEB and PUB absorption coefficient models, (b) PE spectral shifts induced by PUB chromophore substitution at chromophore binding sites, (c) specific absorption-sensitive phytoplankton absorption modeling, (d) total constituent backscattering modeling, (e) unmodeled carotinoid and phycocyanin absorption that are not now accounted for in the chlorophyll-dominated phytoplankton absorption coefficient model, and (f) iterative inversion techniques to solve for six constituents with only five radiances. Although considerable progress has been made toward the satellite recovery of PE absorption, the maturity of the retrieval is presently insufficient for routine global application. Instead it must currently be used on a regional basis where localized ship and aircraft validation can be made available. The algorithm was developed for the MODIS (Moderate-Resolution Imaging Spectroradiometer) sensor but is applicable to any sensor having comparable band locations.

  11. Measurement of Acoustic Attenuation and Absorption Coefficients using Thermometry

    Microsoft Academic Search

    Hugh Morris; Ian Rivens; Adam Shaw; Gail Ter Haar

    2007-01-01

    Accurate knowledge of both the attenuation and the absorption coefficient of tissue are required when planning an optimal high intensity focused ultrasound treatment. A novel technique for simple measurement of this parameters has been developed in which a thin-film thermocouple (TFT) is placed between two layers of tissue of different thicknesses. The sample can be rotated about an axis through

  12. Lifshitz tails for the Interband Light Absorption Coefficient

    E-print Network

    W. Kirsch; M. Krishna

    2009-03-31

    In this paper we consider the Interband Light Absorption Coefficient for various models. We show that at the lower and upper edges of the spectrum the Lifshitz tails behaviour of the density of states implies similar behaviour for the ILAC at appropriate energies. The Lifshitz tails property is also exhibited at some points corresponding to the internal band edges of the density of states.

  13. Tomographic Reconstruction of 2-D Absorption Coefficient Distributions from a Limited Set of Infrared Absorption Data

    Microsoft Academic Search

    E. D. TORNIAINEN; F. C. GOULDIN

    1998-01-01

    The results of infrared absorption experiments, performed on a steady, nonreacting flow of methane and argon to test a new inversion method for tomographic reconstruction of spatially nonuniform distributions, are presented. The absorption coefficient distributions to be reconstructed are expressed as a weighted sum of Karhunen-Loève eigenfunctions, formed by applying the Karhunen-Loève procedure to a training set containing a priori

  14. The 2008 North Atlantic Spring Bloom Experiment: Spectral Particulate Absorption Coefficients

    NASA Astrophysics Data System (ADS)

    Kallin, E. B.; Rehm, E.; Perry, M.; Sauer, M.; Drzewianowski, A.; Sieracki, M.; Poulton, N.; D'Asaro, E.

    2008-12-01

    During the 2008 North Atlantic Spring Bloom Experiment (NAB08), spectral absorption coefficients of particulate material were measured by two techniques: the Quantitative Filter Technique (QFT) on water samples collected from the CTD/Rosette and in-water measurements collected with a single ac-9 as the difference between filtered and unfiltered profiles. Phytoplankton and non-phytoplankton absorption spectra from the QFT were determined by the Kishino methanol extraction procedure; these coefficients provide the basis for enhanced separation of ac-9 particulate absorption coefficients into phytoplankton and non- phytoplankton components. The blue-to-red ratio (440nm:676nm) of phytoplankton absorption, a diagnostic of photoprotective pigmentation, varied by approximately 25%. Visible and UV light penetration was measured by two radiometric profiling systems: a free-fall hyperspectral radiometer (350-800nm) deployed from the ship and a hyperspectral radiometer mounted on a Lagrangian mixed-layer float (320-950nm). Despite persistent cloud cover, phytoplankton absorption at wavelengths typically dominated by microsporin-like amino acids (MAAs, ~ 320nm) were observed in all spectra in the upper 50m. Phytoplankton community composition changed over the course of the experiment, from a diatom-dominated assemblage to a mixed community of dinoflagellates, picoeukaryotes, and heterotrophic flagellates.

  15. Optimization of the acoustic absorption coefficients of certain functional absorbents

    NASA Technical Reports Server (NTRS)

    Pocsa, V.; Biborosch, L.; Veres, A.; Halpert, E.; Lorian, R.; Botos, T.

    1974-01-01

    The sound absorption coefficients of some functional absorbents (mineral wool plates) are determined by the reverberation chamber method. The influence of the angle of inclination of the sound absorbing material with respect to the surface to be treated is analyzed as well as the influence of the covering index, defined as the ratio of the designed area of a plate and the area of the treated surface belonging to another plate. As compared with the conventional method of applying sound-absorbing plates, the analyzed structures have a higher technological and economical efficiency. The optimum structure corresponds to an angle of inclination of 15 deg and a covering index of 0.8.

  16. Use of textile nanofibers to improve the sound absorption coefficient of drilled panels for acoustic

    E-print Network

    Paris-Sud XI, Université de

    Use of textile nanofibers to improve the sound absorption coefficient of drilled panels with high porosity, high sound absorption coefficient and a mass and thickness negligible On the other hand, to improve the sound absorption coefficient of drilled panels. In order to obtain this objective

  17. Calculation of self-absorption coefficients of calcium resonance lines in the case of a CaCl 2-water plasma

    NASA Astrophysics Data System (ADS)

    Hannachi, R.; Cressault, Y.; Teulet, Ph.; Gleizes, A.; Lakhdar, Z. Ben

    2008-10-01

    The resonance escape factors for the lines emitted by a neutral calcium atom Ca I at 4226.73 Å and of ionic calcium Ca II at 3933.66 Å and at 3968.47 Å are calculated assuming a Voigt profile and in the case of CaCl 2-water plasma. The dependence of the escape factor on the optical thickness ?0 from the line center which itself depends on the two main spectral line shape broadening mechanisms (pressure and Doppler effects) are considered. The variation of the resonance escape factors with the temperature, the CaCl 2 molar proportion and the size of the plasma are also investigated. This calculation is useful for the application of Laser-Induced Breakdown Spectroscopy in the quantitative analysis of elemental composition. Its application allows us to reduce the non-linearities in the relation between resonance lines intensities of calcium in our case and its concentration.

  18. Variability in the chlorophyll-specific absorption coefficients of natural phytoplankton: Analysis and parameterization

    Microsoft Academic Search

    Annick Bricaud; Marcel Babin; André Morel; Hervé Claustre

    1995-01-01

    Variability in the chlorophyll (chl) a-specific absorption coefficients of living phytoplankton aph*(lambda) was analyzed using a data set including 815 spectra determined with the wet filter technique in different regions of the world ocean (covering the chlorophyll concentration range 0.02-25 mg m-3). The aph* values were observed to decrease rather regularly from oligotrophic to eutrophic waters, spanning over more than

  19. Absorption of water and lubricating oils into porous nylon

    NASA Technical Reports Server (NTRS)

    Bertrand, P. A.

    1995-01-01

    Oil and water absorption from air into sintered porous nylon can be described by infiltration into the pores of the material. This process can be modeled by a diffusion-like mechanism. For water absorption, we find a formal diffusion coefficient of 1.5 x 10(exp -4)sq cm/min when the nylon is initially dry. The diffusion coefficient is 4 x 10(exp -6)sq cm/min when the nylon is oil-impregnated prior to air exposure. In a 52% RH atmosphere, dry nylon absorbs 3% w/w water, and oil-impregnated nylon absorbs 0.6% w/w water. For oil absorption there are three steps: (1) surface absorption and infiltration into (2) larger and (3) smaller pores. Surface absorption is too fast to be measured in these experiments. The diffusion coefficient for the second step is 6 x 10(exp -4)sq cm/min for SRG-60 oil into dry nylon and 4 x 10(exp -4)sq cm/min for air-equilibrated nylon. The diffusion coefficient for the third step is about 1 x 10(exp -6)sq cm/min for both cases. The total amount of oil absorbed is 31% w/w. The interaction between water and nylon is not as strong as that between water and cotton-phenolic: oil can replace water, and only a small amount of water can enter previously oil-impregnated nylon.

  20. Microwave Resonator Measurements of Atmospheric Absorption Coefficients: A Preliminary Design Study

    NASA Technical Reports Server (NTRS)

    Walter, Steven J.; Spilker, Thomas R.

    1995-01-01

    A preliminary design study examined the feasibility of using microwave resonator measurements to improve the accuracy of atmospheric absorption coefficients and refractivity between 18 and 35 GHz. Increased accuracies would improve the capability of water vapor radiometers to correct for radio signal delays caused by Earth's atmosphere. Calibration of delays incurred by radio signals traversing the atmosphere has applications to both deep space tracking and planetary radio science experiments. Currently, the Cassini gravity wave search requires 0.8-1.0% absorption coefficient accuracy. This study examined current atmospheric absorption models and estimated that current model accuracy ranges from 5% to 7%. The refractivity of water vapor is known to 1% accuracy, while the refractivity of many dry gases (oxygen, nitrogen, etc.) are known to better than 0.1%. Improvements to the current generation of models will require that both the functional form and absolute absorption of the water vapor spectrum be calibrated and validated. Several laboratory techniques for measuring atmospheric absorption and refractivity were investigated, including absorption cells, single and multimode rectangular cavity resonators, and Fabry-Perot resonators. Semi-confocal Fabry-Perot resonators were shown to provide the most cost-effective and accurate method of measuring atmospheric gas refractivity. The need for accurate environmental measurement and control was also addressed. A preliminary design for the environmental control and measurement system was developed to aid in identifying significant design issues. The analysis indicated that overall measurement accuracy will be limited by measurement errors and imprecise control of the gas sample's thermodynamic state, thermal expansion and vibration- induced deformation of the resonator structure, and electronic measurement error. The central problem is to identify systematic errors because random errors can be reduced by averaging. Calibrating the resonator measurements by checking the refractivity of dry gases which are known to better than 0.1% provides a method of controlling the systematic errors to 0.1%. The primary source of error in absorptivity and refractivity measurements is thus the ability to measure the concentration of water vapor in the resonator path. Over the whole thermodynamic range of interest the accuracy of water vapor measurement is 1.5%. However, over the range responsible for most of the radio delay (i.e. conditions in the bottom two kilometers of the atmosphere) the accuracy of water vapor measurements ranges from 0.5% to 1.0%. Therefore the precision of the resonator measurements could be held to 0.3% and the overall absolute accuracy of resonator-based absorption and refractivity measurements will range from 0.6% to 1.

  1. Satellite Retrieval of the Absorption Coefficient of Phytoplankton Phycoerythrin Pigment: Theory and Feasibility Status

    Microsoft Academic Search

    Frank E. Hoge; C. Wayne Wright; Paul E. Lyon; Robert N. Swift; James K. Yungel

    1999-01-01

    Oceanic radiance model inversion methods are used to develop a comprehensive algorithm for retrieval of the absorption coefficients of phycourobilin (PUB) pigment, type I phycoerythrobilin (PEB) pigment rich in PUB, and type II PEB deficient in PUB pigment (together with the usual big three inherent optical properties: the total backscattering coefficient and the absorption coefficients of chromophoric dissolved organic matter

  2. Heat exchange model in absorption chamber of water-direct-absorption-typed laser energy meter

    NASA Astrophysics Data System (ADS)

    Feng Wei, Ji; Qun Sun, Li; Zhang, Kai; Hu, XiaoYang; Zhou, Shan

    2015-04-01

    The interaction between laser and water flow is very complicated in the absorption chamber of a high energy laser (HEL) energy meter which directly uses water as an absorbing medium. Therefore, the heat exchange model cannot be studied through traditional methods, but it is the most important factor to improve heat exchange efficiency in the absorption chamber. After the exchanges of heat and mass were deeply analyzed, experimental study and numerical fitting were brought out. The original testing data of laser power and water flow temperature at one moment were utilized to calculate those at the next moment, and then the calculated temperature curve was compared with the measured one. If the two curves matched well, the corresponding coefficient was obtained. Meanwhile, numerous experiments were performed to study the effects of laser power, duration, focal spot scale, and water flow rate on heat exchange coefficient. In addition, the relationship between water phase change and heat exchange was analyzed. The heat exchange coefficient was increased by optimizing the construction of the absorption chamber or increasing water flow rate. The results provide the reference for design of water-direct-absorption-typed HEL energy meters, as well as for analysis of the interaction between other similar lasers and water flow.

  3. Octanol\\/Water Partition Coefficients of Chloronaphthalenes

    Microsoft Academic Search

    T. PUZYN; J. FALANDYSZ

    2005-01-01

    Computational n-octanol\\/water partition coefficients data for 75 chloronaphthalene congeners based on the Ghose, Pritchet, and Crippen algorithm; the Moriguchi method; and two QSPR models with principal component regression and partial least-squares (PLS) regression calculations are presented. Chloronaphthalenes log KOW data obtained after PLS are characterized by the lowest root mean square error (RMSEP = 0.0190), whereas results from the Ghose,

  4. LE JOURNAL DE PHYSIQUE COEFFICIENTS D'ABSORPTION DES RAYONS GAMMA DU RADIUM C'

    E-print Network

    Paris-Sud XI, Université de

    LE JOURNAL DE PHYSIQUE ET LE RADIUM COEFFICIENTS D'ABSORPTION DES RAYONS GAMMA DU RADIUM C' Par H'Université de Bruxelles.) Sommaire. - Nous avons mesuré les coefficients d'absorption des rayons gamma du radium de ces corps en utilisant une préparation de 1 709 milligrammes de radium en équilibre avec ses

  5. [Estimation of DOC concentrations using CDOM absorption coefficients: a case study in Taihu Lake].

    PubMed

    Jiang, Guang-Jia; Ma, Rong-Hua; Duan, Hong-Tao

    2012-07-01

    Dissolved organic carbon (DOC) is the largest organic carbon stock in water ecosystems, which plays an important role in the carbon cycle in water. Chromophoric dissolved organic matter (CDOM), an important water color variation, is the colored fraction of DOC and its absorption controls the instruction of light under water. The available linkage between DOC concentration and CDOM absorptions enables the determination of DOC accumulations using remote sensing reflectance or radiance in lake waters. The present study explored the multi-liner relationship between CDOM absorptions [a(g) (250) and a(g) (365)] and DOC concentrations in Taihu Lake, based on the available data in 4 cruises (201005, 201101, 201103, 201105) (totally 183 sampling sites). Meanwhile, the results were validated with the data of the experiment carried out from August 29 to September 2, 2011 in Taihu Lake (n = 27). Furthermore, a universal pattern of modeling from remote sensing was built for lake waters. The results demonstrated that this method provided more satisfying estimation of DOC concentrations in Taihu Lake. Except the data obtained in January 2011, the fitted results of which were not conductive to the winter dataset (201101) in Taihu Lake, due to the diverse sources and sinks of DOC and CDOM, the multi-liner relationship was robust for the data collected in the other three cruises (R2 = 0.64, RMSE = 14.31%, n = 164), which was validated using the 201108 sampling dataset (R2 = 0.67, RMSE = 10.58%, n = 27). In addition, the form of the statistic model is universal, to some extent, for other water areas, however, there is difference in the modeling coefficients. Further research should be focused on the parameterization using local data from different lakes, which provides effective methodology for the estimation of DOC concentrations in lakes and other water regions. PMID:23002596

  6. FTIR-spectrometer-determined absorption coefficients of seven hydrazine fuel gases - Implications for laser remote sensing

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Grant, W. B.

    1984-01-01

    The absorption spectra of three hydrazines and four of their air-oxidation products were measured in the 9-12-micron spectral region with a Fourier transform infrared (FTIR) spectrometer with a 0.05-kayser resolution to determine absorption coefficients at CO2 and tunable diode laser wavelengths. The measurements agreed well with published CO2 laser determinations for many of the absorption coefficients, except where the published values are thought to be in error. The coefficients were then used to estimate the sensitivity for remote detection of these gases using CO2 and tunable diode lasers in long-path differential absorption measurements.

  7. Measurement of the absorption coefficient of acoustical materials using the sound intensity method

    NASA Technical Reports Server (NTRS)

    Atwal, Mahabir S.; Crocker, Malcolm J.

    1987-01-01

    In this study the possibility of using the two-microphone sound intensity technique to measure the normal incidence and the random incidence sound absorption coefficient was investigated. The normal incidence absorption coefficient was determined by measuring the intensity incidence on the sample and the intensity reflected by the sample placed in an anechoic chamber. The random incidence absorption coefficient was determined by measuring the intensity incident on the sample and the intensity reflected by the sample placed in a reverberation chamber. Absorption coefficient results obtained by the sound intensity technique were compared with standard techniques, namely the reverberation chamber and the standing wave tube. The major advantages of using the sound intensity technique are that it permits 'in situ' measurements and the absorption coefficient for a large range of frequencies can be obtained from a single measurement.

  8. Photon energy absorption coefficients for nuclear track detectors using Geant4 Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Medhat, M. E.; Badiger, N. M.

    2015-01-01

    Geant4 Monte Carlo code simulations were used to solve experimental and theoretical complications for calculation of mass energy-absorption coefficients of elements, air, and compounds. The mass energy-absorption coefficients for nuclear track detectors were computed first time using Geant4 Monte Carlo code for energy 1 keV-20 MeV. Very good agreements for simulated results of mass energy-absorption coefficients for carbon, nitrogen, silicon, sodium iodide and nuclear track detectors were observed on comparison with the values reported in the literatures. Kerma relative to air for energy 1 keV-20 MeV and energy absorption buildup factors for energy 50 keV-10 MeV up to 10 mfp penetration depths of the selected nuclear track detectors were also calculated to evaluate the absorption of the gamma photons. Geant4 simulation can be utilized for estimation of mass energy-absorption coefficients in elements and composite materials.

  9. Sound absorption coefficient in situ: an alternative for estimating soil loss factors.

    PubMed

    Freire, Rosane; Meletti de Abreu, Marco Henrique; Okada, Rafael Yuri; Soares, Paulo Fernando; GranhenTavares, Célia Regina

    2015-01-01

    The relationship between the sound absorption coefficient and factors of the Universal Soil Loss Equation (USLE) was determined in a section of the Maringá Stream basin, Paraná State, by using erosion plots. In the field, four erosion plots were built on a reduced scale, with dimensions of 2.0×12.5m. With respect to plot coverage, one was kept with bare soil and the others contained forage grass (Brachiaria), corn and wheat crops, respectively. Planting was performed without any type of conservation practice in an area with a 9% slope. A sedimentation tank was placed at the end of each plot to collect the material transported. For the acoustic system, pink noise was used in the measurement of the proposed monitoring, for collecting information on incident and reflected sound pressure levels. In general, obtained values of soil loss confirmed that 94.3% of material exported to the basin water came from the bare soil plot, 2.8% from the corn plot, 1.8% from the wheat plot, and 1.1% from the forage grass plot. With respect to the acoustic monitoring, results indicated that at 16kHz erosion plot coverage type had a significant influence on the sound absorption coefficient. High correlation coefficients were found in estimations of the A and C factors of the USLE, confirming that the acoustic technique is feasible for the determination of soil loss directly in the field. PMID:24972796

  10. Intensity dependence of the inverse bremsstrahlung absorption coefficient in hot plasmas

    Microsoft Academic Search

    T. P. Hughes; M. B. Nicholson-Florence

    1968-01-01

    The net absorption coefficient allowing for stimulated emission is derived for intense light in a hot non-relativistic plasma, using a semi-classical approach, which takes into account the non-Maxwellian velocity distribution caused by the strong electric field of the radiation but considers only absorption and emission processes involving a single incident photon. The absorption coefficient is found to vary inversely as

  11. Measurement of the absorption coefficient using the sound-intensity technique

    NASA Technical Reports Server (NTRS)

    Atwal, M.; Bernhard, R.

    1984-01-01

    The possibility of using the sound intensity technique to measure the absorption coefficient of a material is investigated. This technique measures the absorption coefficient by measuring the intensity incident on the sample and the net intensity reflected by the sample. Results obtained by this technique are compared with the standard techniques of measuring the change in the reverberation time and the standing wave ratio in a tube, thereby, calculating the random incident and the normal incident adsorption coefficient.

  12. Absorption of laser radiation in a H-He plasma. I. Theoretical calculation of the absorption coefficient

    Microsoft Academic Search

    James R. Stallcop

    1974-01-01

    The theory for calculating the absorption of laser radiation by hydrogen is outlined for the temperatures and pressures of common laboratory plasmas. Nonhydrogenic corrections for determining the absorption by helium are also included. The coefficients for the absorption of He-Ne laser radiation at the wavelengths of 0.633, 1.15, and 3.39 ?m in a H plasma is presented for temperatures in

  13. Determination of absorption coefficient based on laser beam thermal blooming in gas-filled tube.

    PubMed

    Hafizi, B; Peñano, J; Fischer, R; DiComo, G; Ting, A

    2014-08-01

    Thermal blooming of a laser beam propagating in a gas-filled tube is investigated both analytically and experimentally. A self-consistent formulation taking into account heating of the gas and the resultant laser beam spreading (including diffraction) is presented. The heat equation is used to determine the temperature variation while the paraxial wave equation is solved in the eikonal approximation to determine the temporal and spatial variation of the Gaussian laser spot radius, Gouy phase (longitudinal phase delay), and wavefront curvature. The analysis is benchmarked against a thermal blooming experiment in the literature using a CO? laser beam propagating in a tube filled with air and propane. New experimental results are presented in which a CW fiber laser (1 ?m) propagates in a tube filled with nitrogen and water vapor. By matching laboratory and theoretical results, the absorption coefficient of water vapor is found to agree with calculations using MODTRAN (the MODerate-resolution atmospheric TRANsmission molecular absorption database) and HITRAN (the HIgh-resolution atmospheric TRANsmission molecular absorption database). PMID:25090334

  14. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    PubMed

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. PMID:25465962

  15. Seasonal variability in the light absorption properties of western Arctic waters: Parameterization of the individual components of absorption for ocean color applications

    Microsoft Academic Search

    Atsushi Matsuoka; Victoria Hill; Yannick Huot; Marcel Babin; Annick Bricaud

    2011-01-01

    The light absorption properties of particulate and dissolved materials strongly influence the propagation of visible light in oceanic waters and therefore the accuracy of ocean color algorithms. While the general absorption properties of these materials have been reported for Arctic waters, their seasonal variability remains unknown. We investigated the light absorption coefficients of phytoplankton [a$\\\\varphi$(?)], nonalgal particles [aNAP(?)], and colored

  16. Analytic representation of the silicon absorption coefficient in the indirect transition region

    SciTech Connect

    Geist, J.; Migdall, A.; Baltes, H.P.

    1988-09-15

    The absorption coefficient of silicon over most of the indirect transi region is calculated by fitting an eleven-parameter equation to observed data, an essential step in modeling silicon solar cells./aip/.

  17. Efficient Line-by-Line Calculation of Absorption Coefficients to High Numerical Accuracy

    NASA Technical Reports Server (NTRS)

    Sparks, L.

    1996-01-01

    A simple yet efficient method is presented for calculating spectral absorption coefficients to high numerical accuracy. The accuracy achieved is independent of the sampling interval. The method is applicable to any analytic model of the spectral line shape.

  18. Nano multi-layered spherical quantum dot optimization by PSO algorithm: Maximizing the optical absorption coefficient

    NASA Astrophysics Data System (ADS)

    Zamani, N.; Keshavarz, A.; Nadgaran, H.

    2015-01-01

    In this paper, the maximization of optical absorption coefficient of multi-layer spherical quantum dot (MSQD) has been investigated based on particle swarm optimization (PSO) method. By using this method and numerical solution of Schrödinger equation (energy eigenvalues and eigenvectors are calculated using the fourth-order Runge-Kutta method), optimal MSQD structure has been determined to maximise the optical absorption coefficient. Having introduced the optimal structure, the refractive index changes and effects of pressure and temperature on the optical absorption coefficient of this structure have been studied. The result shows that the maximum total optical absorption coefficient for the optimal structure is equal to 1.33 ×105m-1 and its sensitivity dependence to changes of the first well width is more than that of other parameters.

  19. A method for determination mass absorption coefficient of gamma rays by Compton scattering.

    PubMed

    El Abd, A

    2014-12-01

    A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed. PMID:25241360

  20. Linear and nonlinear optical absorption coefficients of two-electron spherical quantum dot with parabolic potential

    NASA Astrophysics Data System (ADS)

    Çak?r, Bekir; Yakar, Yusuf; Özmen, Ayhan

    2015-02-01

    Linear and nonlinear absorption coefficients of two-electron spherical quantum dot (QD) with parabolic potential are investigated in this paper. Wave functions and energy eigenvalues of the 1s2, 1s1p, 1s1d and 1s1f electronic states have been computed by using an optimization approach, which is a combination of Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothaan (HFR) method. It is found that the strength of S?P transition is stronger than P?D and D?F transitions. Also the peak positions and amplitudes of the absorption coefficients are sensitive to the electron spin. It should be noted that the peak positions and amplitudes of absorption coefficients are strongly dependent on the parabolic potential. Additionally, dot radius, impurity charge, incident optical intensity and relaxation time have a great influence on the linear and nonlinear absorption coefficients.

  1. Continuous wavelet-transform analysis of photoacoustic signal waveform to determine optical absorption coefficient

    NASA Astrophysics Data System (ADS)

    Hirasawa, T.; Ishihara, M.; Tsujita, K.; Hirota, K.; Irisawa, K.; Kitagaki, M.; Fujita, M.; Kikuchi, M.

    2012-02-01

    In photo-acoustic (PA) imaging, valuable medical applications based on optical absorption spectrum such as contrast agent imaging and blood oxygen saturation measurement have been investigated. In these applications, there is an essential requirement to determine optical absorption coefficients accurately. In present, PA signal intensities have been commonly used to determine optical absorption coefficients. This method achieves practical accuracy by combining with radiative transfer analysis. However, time consumption of radiative transfer analysis and effects of signal generation efficiencies were problems of this method. In this research, we propose a new method to determine optical absorption coefficients using continuous wavelet transform (CWT). We used CWT to estimate instantaneous frequencies of PA signals which reflects optical absorption distribution. We validated the effectiveness of CWT in determination of optical absorption coefficients through an experiment. In the experiment, planar shaped samples were illuminated to generate PA signal. The PA signal was measured by our fabricated PA probe in which an optical fiber and a ring shaped P(VDFTrFE) ultrasound sensor were coaxially aligned. Optical properties of samples were adjusted by changing the concentration of dye solution. Tunable Ti:Sapphire laser (690 - 1000 nm) was used as illumination source. As a result, we confirmed strong correlation between optical absorption coefficients of samples and the instantaneous frequency of PA signal obtained by CWT. Advantages of this method were less interference of light transfer and signal generation efficiency.

  2. Measurement of the sound absorption coefficient of materials with a new sound intensity technique

    Microsoft Academic Search

    Angelo Farina; Anna Torelli

    The paper presents a completely new measurement technique of the sound absorption properties of materials, based on the measurements of active intensity and sound energy density. It allows one to measure the absorption coefficient with a wide band excitation, to use frequency bands of any width and to make measurements both inside a tube or in situ. The intensity technique

  3. Experiment to Determine the Absorption Coefficient of Gamma Rays as a Function of Energy.

    ERIC Educational Resources Information Center

    Ouseph, P. J.; And Others

    1982-01-01

    Simpler than x-ray diffractometer experiments, the experiment described illustrates certain concepts regarding the interaction of electromagnetic rays with matter such as the exponential decrease in the intensity with absorber thickness, variation of the coefficient of absorption with energy, and the effect of the K-absorption edge on the…

  4. Absorption of laser radiation in a H-He plasma. II. Experimental measurement of the absorption coefficient

    Microsoft Academic Search

    Kenneth W. Billman; Paul D. Rowley; James R. Stallcop; Leroy Presley

    1974-01-01

    The absorption coefficients of 0.633-, 1.15-, and 3.39-?m laser radiation for a homogeneous H-He plasma have been measured in the temperature range of 12.2 to 21.7 (× 103 °K) and in the electron number density range 0.45 to 6.5 (× 1017 cm?3). Good agreement is found between the experimentally determined total absorption for each of the wavelengths and that calculated

  5. Absorption and Scattering Coefficients: A Biophysical-Chemistry Experiment Using Reflectance Spectroscopy

    ERIC Educational Resources Information Center

    Cordon, Gabriela B.; Lagorio, M. Gabriela

    2007-01-01

    A biophysical-chemistry experiment, based on the reflectance spectroscopy for calculating the absorption and scattering coefficients of leaves is described. The results show that different plants species exhibit different values for both the coefficients because of their different pigment composition.

  6. Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

    NASA Technical Reports Server (NTRS)

    May, R. D.; Molina, L. T.; Webster, C. R.

    1988-01-01

    A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

  7. Accelerated line-by-line calculation of spectral absorption coefficients with high numerical accuracy

    NASA Technical Reports Server (NTRS)

    Sparks, L.

    1995-01-01

    To model radiative transfer through the atmosphere with high accuracy, one must resort to the calculation of spectral absorption coefficients on a line-by-line basis. The calculation of these coefficients is computationally expensive for three reasons: (1) thousands of spectral lines can contribute to absorption at a single frequency; (2) the tails of spectral line profiles are long (i.e., a given line can contribute to absorption over a wide range of frequencies); and (3) the sampling frequencies at which monochromatic radiances are to be calculated must be spaced sufficiently close together to resolve the thinnest lines of interest (e.g., those that arise in the stratosphere). We have developed a new algorithm to accelerate the calculation of spectral absorption coefficients while retaining high numerical accuracy.

  8. COMPARISON OF TELEPHOTOMETER MEASUREMENTS OF EXTINCTION COEFFICIENTS WITH SCATTERING AND ABSORPTION COEFFICIENTS

    EPA Science Inventory

    During the summer of 1979, coefficients for light extinction in the atmosphere were calculated from measurements made with a telephotometer placed 251 m from a black target in Research Triangle Park, North Carolina. The results are well correlated (r = 0.92 to 0.96) with integrat...

  9. Evaluation of ammonia absorption coefficients by photoacoustic spectroscopy for detection of ammonia levels in human breath

    NASA Astrophysics Data System (ADS)

    Dumitras, D. C.; Dutu, D. C.; Matei, C.; Cernat, R.; Banita, S.; Patachia, M.; Bratu, A. M.; Petrus, M.; Popa, C.

    2011-04-01

    Photoacoustic spectroscopy represents a powerful technique for measuring extremely low absorptions independent of the path length and offers a degree of parameter control that cannot be attained by other methods. We report precise measurements of the ammonia absorption coefficients at the CO2 laser wavelengths by using a photoacoustic (PA) cell in an extracavity configuration and we compare our results with other values reported in the literature. Ammonia presents a clear fingerprint spectrum and high absorption strengths in the CO2 wavelengths region. Because more than 250 molecular gases of environmental concern for atmospheric, industrial, medical, military, and scientific spheres exhibit strong absorption bands in the region 9.2-10.8 ?m, we have chosen a frequency tunable CO2 laser. In the present work, ammonia absorption coefficients were measured at both branches of the CO2 laser lines by using a calibrated mixture of 10 ppm NH3 in N2. We found the maximum absorption in the 9 ?m region, at 9R(30) line of the CO2 laser. One of the applications based on the ammonia absorption coefficients is used to measure the ammonia levels in exhaled human breath. This can be used to determine the exact time necessary at every session for an optimal degree of dialysis at patients with end-stage renal disease.

  10. Linear and nonlinear optical absorption coefficients and binding energy of a spherical quantum dot

    NASA Astrophysics Data System (ADS)

    Çak?r, Bekir; Yakar, Yusuf; Özmen, Ayhan; Sezer, M. Özgür; ?ahin, Mehmet

    2010-04-01

    The binding energy and wavefunctions of the 1s, 1p, 1d and 1f energy states of a spherical quantum dot (QD) with parabolic potential were calculated by using a method which is a combination of the quantum genetic algorithm (QGA) and the Hartree-Fock-Roothaan (HFR) approach. In addition, the linear and the third-order nonlinear optical absorption coefficients based on optical transitions in QDs with and without impurity were calculated. The results show that the parabolic potential has a great effect not only on the binding energies and but also on the optical absorption coefficients. Moreover, the calculated results also reveal that the linear and nonlinear optical absorption coefficients are strongly affected by the existence of impurity and the incident optical intensity.

  11. Calculation of linear and nonlinear optical absorption coefficients of a spherical quantum dot with parabolic potential

    NASA Astrophysics Data System (ADS)

    Yakar, Yusuf; Çak?r, Bekir; Özmen, Ayhan

    2010-05-01

    In the effective mass approximation, we calculated the binding energy and wave function for the 1s-, 1p-, 1d- and 1f-states of a spherical quantum dot (QD) with parabolic potential by using a combination of quantum genetic algorithm (QGA) and Hartree-Fock-Roothaan (HFR) method. In addition, we also investigated the linear and the third-order nonlinear optical absorption coefficients as a function of the incident photon energy for the 1s-1p, 1p-1d and 1d-1f transitions. Our results are shown that the existence of impurity has great influence on optical absorption coefficients. Moreover, the optical absorption coefficients are strongly affected by the incident optical intensity, relaxation time, parabolic potential and dot radius.

  12. Measurement of the absorption coefficient of sound absorbing materials under a synthesized diffuse acoustic field.

    PubMed

    Robin, Olivier; Berry, Alain; Doutres, Olivier; Atalla, Noureddine

    2014-07-01

    This letter proposes an experimental method to estimate the absorption coefficient of sound absorbing materials under a synthesized diffuse acoustic field in free-field conditions. Comparisons are made between experiments conducted with this approach, the standard reverberant room method, and numerical simulations using the transfer matrix method. With a simple experimental setup and smaller samples than those required by standards, the results obtained with the proposed approach do not exhibit non-physical trends of the reverberant room method and provide absorption coefficients in good agreement with those obtained by simulations for a laterally infinite material. PMID:24993232

  13. Co:GGG edge cladding with adjusted absorption coefficients in composite crystals

    NASA Astrophysics Data System (ADS)

    Lee, Huai-Chuan; Meissner, Helmuth E.; Meissner, Oliver R.

    2004-07-01

    Gadolinium Gallium Garnet single crystals doped with cobalt ions are used for suppression of parasitic as edge cladding layers in Nd:Gd3Ga5O12 (Nd:GGG) crystal amplifier plates for heat capacity and other high power solid-state laser applications. Co:GGG absorbs at the lasing wavelength of 1062 nm. Nd:GGG amplifier plates with edge cladding of Co:GGG of adjusted absorption coefficient at 1062 nm will be used as adhesive-free bonded (AFB) composite crystal components in a heat capacity laser system at Lawrence Livermore National Laboratory. Composite formation of Nd:GGG and Co:GGG involves heat treatment. The absorption coefficient of the as-grown Co:GGG single crystal changes as function of heat treatment. We report on a method of reversibly adjusting the absorption coefficient of Co:GGG in a certain range, e.g. for a specific Co ion concentration of 0.0046% between 0.45/cm and 0.95/cm. The interpretation of the reversible adjustment of absorption coefficients based on absorption spectra, site symmetry and cobalt ion valency will be presented

  14. Correlation of octanol\\/water solubility ratios and partition coefficients

    Microsoft Academic Search

    Sirirat Pinsuwan; An Li; Samuel H. Yalkowsky

    1995-01-01

    The partition coefficient between octanol and water in an important physicochemical parameter for characterizing the lipophilicity or hydrophobicity of a compound and it is used in many fields, especially in the environmental and pharmaceutical sciences. The octanol\\/water solubility ratio (S{sub o}\\/S{sub W}) was found to be highly correlated with the octanol\\/water partition coefficient (K{sub ow}) of 82 pharmaceutically and environmentally

  15. 1Octanol\\/Water Partition Coefficient of Ionic Liquids

    Microsoft Academic Search

    Cheng-Huang Choua; Fu-Shan Perng; David Shan; Hill Wong; Wen Cheng Su

    Room temperature ionic liquids are nonvolatile, they can only disperse into the aquatic environment. 1-octanol-water partition coefficient is a measure of the bioconcentration tendency of a chemical in a hydrologic cycle. In this work, 1-octanol-water partition coefficient of 1-ethyl-3-methylimidazolium hexafluoro- phosphate ((emim)(PF6)) and 1-butyl-3-methylimidazolium hexafluorophosphate ((bmim)(PF6)) at 303 K were measured using ultraviolet spectrometer and Karl-Fischer analysis. The 1-octanol\\/water partition

  16. Additions and corrections to the absorption coefficients of CO2 ice - Applications to the Martian south polar cap

    NASA Technical Reports Server (NTRS)

    Calvin, Wendy M.

    1990-01-01

    Reflectance spectra of carbon dioxide frosts were calculated using the optical constants provided by Warren (1986) for the wavelength region 2-6 microns. In comparing these calculated spectra to spectra of frosts observed in the laboratory and on the surface of Mars, problems in the optical constants presented by Warren (1986) became apparent. Absorption coefficients for CO2 ice have been derived using laboratory reflectance measurements and the Hapke (1981) model for calculating diffuse reflectance. This provides approximate values in regions where no data were previously available and indicates where corrections to the compilation by Warren (1986) are required. Using these coefficients to calculate the reflectance of CO2 ice at varying grain sizes indicates that a typical Mariner polar cap spectrum is dominated by absorptions due to CO2 frost or ice at grain sizes that are quite large, probably of the order of millimeters to centimeters. There are indications of contamination of water frost or dust, but confirmation will require more precise absorption coefficients for solid CO2 than can be obtained from the method used here.

  17. Free-free radiative absorption coefficient for the negative argon ion

    Microsoft Academic Search

    Michael S. Pindzola; Hugh P. Kelly

    1976-01-01

    The free-free absorption coefficient for Ar- is calculated at radiation wavelengths of 2000 and 20000 Å for various temperatures. Electron correlation corrections to the Hartree-Fock approximation are obtained by using many-body perturbation theory. Comparison is made with other theoretical methods and experiment.

  18. The free-free absorption coefficient of the negative argon ion

    Microsoft Academic Search

    K. L. Bell; K. A. Berrington

    1987-01-01

    The free-free absorption coefficient for Ar(-) is calculated at a wide range of radiation wavelengths and temperatures. The calculation employs a multichannel theory based upon the R-matrix method for electron-atom collisions. Comparison is made with other theoretical methods and with experiment. Highly satisfactory agreement exists with the bremsstrahlung emissivity experimental data of Ranson et al. (1977).

  19. How to measure and predict the molar absorption coefficient of a protein

    Microsoft Academic Search

    C. Nick Pace; Felix Vajdos; Lanette Fee; Gerald Grimsley; Theronica Gray

    1995-01-01

    The molar absorption coefficient, E, of a protein is usually based on concentrations measured by dry weight, ni- trogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring E for a protein. (This method is described by Gill and von Hippel (1989, Anal Biochem 182:319- 3261 and is based on

  20. The use of the Milne-Eddington absorption coefficient for radiative heat transfer in combustion systems

    Microsoft Academic Search

    J. D. Felske; C. L. Tien

    1977-01-01

    The applicability of the Milne-Eddington absorption coefficient approximation is discussed in relation to the calculation of radiative transport involving the two distinct types of species produced in combustion systems - gases and soot particles. The approximation is found to apply well to hydrocarbon soot particles and as a result analytical closed-form solutions are derived for the radiative heat transfer inside

  1. Inverse bremsstrahlung absorption coefficient and initiation of laser- supported detonation waves in air

    Microsoft Academic Search

    Winslow

    1973-01-01

    The inverse bremsstrahlung absorption coefficient in LASNEX was modified ; for application to laser effects calculations at temperatures below 10 eV. These ; modifications are described and the initiation condition for a laser-supported ; detonation (LSD) wave is crudely estimated for air in the vicinity of a solid ; target. (auth)

  2. Comparison of linear reconstruction techniques for 3D DPDW imaging of absorption coefficient

    Microsoft Academic Search

    Richard J. Gaudette; David A. Boas; Dana H. Brooks; Charles A. Dimarzio; Misha E. Kilmer; Eric L. Miller

    In this paper we examine the performance of a numbe r of linear techniques for reconstructing the 3-D d istribution of absorption coefficient within a highly scattering m edium using the diffuse photon density wave (DPDW) approximation. The simulation consists of a coplanar array of sour ces and detectors at the boundary of an infinite sl ab medium. The primary

  3. Absorption coefficients of solid NH3 from 50 to 7000 per cm

    NASA Technical Reports Server (NTRS)

    Sill, G.; Fink, U.; Ferraro, J. R.

    1980-01-01

    Thin-film spectra of solid NH3 at a resolution of 1 per cm were used to determine its absorption coefficient over the range 50-7000 per cm. The thin films were formed inside a liquid N2 cooled dewar using a variety of substrates and dewar windows. The spectra were recorded with two Fourier spectrometers, one covering the range from 1 to 4 microns and the other from 2.6 to 200 microns. The thickness of the films was measured with a laser interference technique. The absorption coefficients were determined by application of Lambert's law and by a fitting procedure to the observed spectra using thin-film theory. Good agreement was found with the absorption coefficients recently determined by other investigators over a more restricted wavelength range. A metastable phase was observed near a temperature of 90 K and its absorption coefficient is reported. No other major spectral changes with temperature were noted for the range 88-120 K.

  4. Diffuse reflectance spectroscopy as a tool to measure the absorption coefficient in skin: system calibration.

    PubMed

    Karsten, A E; Singh, A; Karsten, P A; Braun, M W H

    2013-02-01

    An individualised laser skin treatment may enhance the treatment and reduces risks and side-effects. The optical properties (absorption and scattering coefficients) are important parameters in the propagation of laser light in skin tissue. The differences in the melanin content of different skin phototypes influence the absorption of the light. The absorption coefficient at the treatment wavelength for an individual can be determined by diffuse reflectance spectroscopy, using a probe containing seven fibres. Six of the fibres deliver the light to the measurement site and the central fibre collects the diffused reflected light. This is an in vivo technique, offering benefits for near-real-time results. Such a probe, with an effective wavelength band from 450 to 800 nm, was used to calibrate skin-simulating phantoms consisting of intralipid and ink. The calibration constants were used to calculate the absorption coefficients from the diffuse reflectance measurements of three volunteers (skin phototypes, II, IV and V) for sun-exposed and non-exposed areas on the arm. PMID:22410734

  5. Measurements of the optical absorption coefficient of Ar8+ ion implanted silicon layers using the photothermal radiometry and the modulated free carrier absorption methods

    NASA Astrophysics Data System (ADS)

    Chrobak, ?.; Mali?ski, M.; Pawlak, M.

    2014-11-01

    This paper presents a method of the measurement of the optical absorption coefficient of the Ar8+ ions implanted layers in the p-type silicon substrate. The absorption coefficient is calculated using a value of the attenuation of amplitudes of a photothermal radiometry (PTR) and/or a modulation free carrier absorption (MFCA) signals and the implanted layer thickness calculated by means of the TRIM program. The proposed method can be used to indicate the amorphization of the ions implanted layers.

  6. Traffic-related differences in indoor and personal absorption coefficient measurements in Amsterdam, the Netherlands

    NASA Astrophysics Data System (ADS)

    Wichmann, Janine; Janssen, Nicole A. H.; van der Zee, Saskia; Brunekreef, Bert

    Population studies indicate that study participants living near major roads are more prone to chronic respiratory symptoms, lung function decrements and hospital admissions for asthma. The majority of the studies used proxy measures, such as distance to major roads or traffic intensity in the surroundings of the home. Few studies have communicated findings of concurrently performed measurements of outdoor, indoor and personal air pollution in urban streets with high- and low-traffic density. Measuring light absorption or reflectance of particulate matter (PM) collected on filters is an alternative method to determine elemental carbon, a marker for particles produced by incomplete combustion, compared to expensive and destructive analytical methods. This study sets out to test the null hypothesis that there is no difference in personal and indoor filter absorption coefficients for participants living along busy and quiet roads in Amsterdam. In one study we measured personal and indoor absorption coefficients in a sample of adults (50-70 years) and, in another study, the indoor levels in a population of adults (50-70 years) and school children (10-12 years). In the first study, the ratios of personal and indoor absorption coefficients in homes along busy roads compared with homes on quiet streets were significantly higher by 29% for personal measurements ( n=16 days, p<0.001), and by 19% for indoor measurements ( n=20, p<0.001), while in the second study, the ratio for the indoor measurements was higher by 26% ( n=25 days, p<0.05). Exposure differences between homes along busy compared to homes along quiet streets remained and significant after adjustment for potential indoor sources (such as cooking and use of unvented heating appliances). This study therefore provides tentative support for the use of the type of road as proxy measure for indoor and personal absorption coefficient measurements in epidemiological studies due to the limitations of the study.

  7. Correlation between oral drug absorption in humans and apparent drug permeability coefficients in human intestinal epithelial (Caco-2) cells

    Microsoft Academic Search

    P. Artursson; J. Karlsson

    1991-01-01

    Monolayers of a well differentiated human intestinal epithelial cell line, Caco-2, were used as a model to study passive drug absorption across the intestinal epithelium. Absorption rate constants (expressed as apparent permeability coefficients) were determined for 20 drugs and peptides with different structural properties. The permeability coefficients ranged from approximately 5 x 10{sup - 8} to 5 x 10{sup -

  8. How to measure and predict the molar absorption coefficient of a protein.

    PubMed Central

    Pace, C. N.; Vajdos, F.; Fee, L.; Grimsley, G.; Gray, T.

    1995-01-01

    The molar absorption coefficient, epsilon, of a protein is usually based on concentrations measured by dry weight, nitrogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring epsilon for a protein. (This method is described by Gill and von Hippel [1989, Anal Biochem 182:319-326] and is based on data from Edelhoch [1967, Biochemistry 6:1948-1954]). The absorbance of a protein at 280 nm depends on the content of Trp, Tyr, and cystine (disulfide bonds). The average epsilon values for these chromophores in a sample of 18 well-characterized proteins have been estimated, and the epsilon values in water, propanol, 6 M guanidine hydrochloride (GdnHCl), and 8 M urea have been measured. For Trp, the average epsilon values for the proteins are less than the epsilon values measured in any of the solvents. For Tyr, the average epsilon values for the proteins are intermediate between those measured in 6 M GdnHCl and those measured in propanol. Based on a sample of 116 measured epsilon values for 80 proteins, the epsilon at 280 nm of a folded protein in water, epsilon (280), can best be predicted with this equation: epsilon (280) (M-1 cm-1) = (#Trp)(5,500) + (#Tyr)(1,490) + (#cystine)(125) These epsilon (280) values are quite reliable for proteins containing Trp residues, and less reliable for proteins that do not. However, the Edelhoch method is convenient and accurate, and the best approach is to measure rather than predict epsilon. PMID:8563639

  9. Heat/Mass Transfer Coefficients of an Absorber in Absorption Refrigeration System

    NASA Astrophysics Data System (ADS)

    Fujita, Isamu; Hihara, Eiji

    This paper presents a new method to calculate heat and mass transfer coefficients applicable to the vertical tube or plate type absorber of absorption refrigeration system. Conventional method for calculating the coefficients using logarithmic mean temperature/ concentration differences is criticized for its lacking in the theoretical rationality and usually giving untrue values except some limited situations such that temperature of the solution can be assumed to change linearly along the heat transfer surface. The newly introduced method, which is intended to overcome this difficulty, is verified by numerical simulation and is accompanied by an example applied to the experimental results.

  10. X-Ray Attenuation Coefficients from 13 to 80 Mev for Hydrogen, Carbon, Water, and Aluminum

    Microsoft Academic Search

    J. M. Wyckoff; H. W. Koch

    1960-01-01

    The x-ray attenuation coefficients for hydrogen, carbon, water, and aluminum have been measured in the energy range from 13 to 80 Mev by placing varying lengths of attenuators in a 90-Mev bremsstrahlung beam in a good geometry experiment using a large sodium-iodide total-absorption spectrometer as the detector. In the hydrogen case, a difference method employing cyclohexane (C6H12) and graphite was

  11. Water Absorption by Cracked Mustard 1

    Microsoft Academic Search

    X. ZHANG; G. H. BRUSEWITZ

    1993-01-01

    Cereal Chem. 70(2):133-136 The water absorption rate was determined for whole mustard seed to be 1.58 X 10-7 cm 2 \\/sec for whole seeds, was used in the diffusion and for seed cracked by seven cracking treatments, including two types equation to derive an equivalent average particle diameter. The equivalent of mills, three roller-mill gaps, two hammer-mill feed rates, three

  12. Water vapor-nitrogen absorption at CO2 laser frequencies

    NASA Technical Reports Server (NTRS)

    Peterson, J. C.; Thomas, M. E.; Nordstrom, R. J.; Damon, E. K.; Long, R. K.

    1979-01-01

    The paper reports the results of a series of pressure-broadened water vapor absorption measurements at 27 CO2 laser frequencies between 935 and 1082 kaysers. Both multiple traversal cell and optoacoustic (spectrophone) techniques were utilized together with an electronically stabilized CW CO2 laser. Comparison of the results obtained by these two methods shows remarkable agreement, indicating a precision which has not been previously achieved in pressure-broadened studies of water vapor. The data of 10.59 microns substantiate the existence of the large (greater than 200) self-broadening coefficients determined in an earlier study by McCoy. In this work, the case of water vapor in N2 at a total pressure of 1 atm has been treated.

  13. Interference absorption coefficient of X-rays in crystals in the presence of temperature gradient

    Microsoft Academic Search

    V. R. Kocharyan; R. Sh. Aleksanyan; K. G. Truni

    2010-01-01

    We investigate experimentally and theoretically the behavior of the interference coefficient of absorption of X-ray radiation\\u000a of a quartz single crystal in Laue geometry in the presence of temperature gradient. The total intensity of transmitted X-ray\\u000a radiation and that reflected from different families of reflecting atomic planes of the quartz single crystal has been recorded.\\u000a It was shown that with

  14. How to measure and predict the molar absorption coefficient of a protein

    Microsoft Academic Search

    C. N. Pace; F. Vajdos; L. Fee; G. Grimsley; T. Gray

    1998-01-01

    Abstract The molar absorption coefficient, E, of a protein is usually based on concentrations measured by dry weight, ni- trogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuri= (#Trp)(5,500) + (#Tyr)(1,490) + (#cystine)(l25). These ~(280) values are quite reliable for proteins containing Trp residues, and less reliable for proteins

  15. Assessment of the Titanium Dioxide Absorption Coefficient by Grazing-An-

    E-print Network

    notes Assessment of the Titanium Dioxide Absorption Coefficient by Grazing-An- gle Fourier of the superficial TiO2 layer affects the biological response of titanium-based materials.6­8 Due to its effects. In particular, we selected the amorphous TiO2 layer present on the surfaces of bulk titanium (cpTi) and Ti6Al4V

  16. Water- Lithium Bromide-?- Butyrolactone Absorption Refrigerating Machine

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Uemura, Tadashi

    This investigation was carried out in order to find corrosion inhibitors which would be effective in controlling the corrosion for the water-lithium bromide-?-butyrolactone (20 moles water/1 mole ?-butyrolactone) absorption refrigerating machine. The experiments were carried out on continuous boiling test, intermittent boiling test and galvanic corrosion test with the use of organic inhibitors and inorganic inhibitors in ?-butyrolactone aqueous solution of lithium bromide. The metals used in these corrosion tests were mainly SS 41 and copper. From these experimental results, the most suitable corrosion inhibitors for SS 41 and copper in ?-butyrolactone aqueous solution of lithium bromide Were recognized to be benzotriazole, tolyltriazole and lithium molybdate.

  17. The influence of water mixtures on the dermal absorption of glycol ethers

    SciTech Connect

    Traynor, Matthew J. [Toxicology Unit, Institute for Research on Environment and Sustainability and Medical School, University of Newcastle upon Tyne, Newcastle NE1 7RU (United Kingdom); Wilkinson, Simon C. [Toxicology Unit, Institute for Research on Environment and Sustainability and Medical School, University of Newcastle upon Tyne, Newcastle NE1 7RU (United Kingdom); Williams, Faith M. [Toxicology Unit, Institute for Research on Environment and Sustainability and Medical School, University of Newcastle upon Tyne, Newcastle NE1 7RU (United Kingdom)]. E-mail: F.M.Williams@ncl.ac.uk

    2007-01-15

    Glycol ethers are solvents widely used alone and as mixtures in industrial and household products. Some glycol ethers have been shown to have a range of toxic effects in humans following absorption and metabolism to their aldehyde and acid metabolites. This study assessed the influence of water mixtures on the dermal absorption of butoxyethanol and ethoxyethanol in vitro through human skin. Butoxyethanol penetrated human skin up to sixfold more rapidly from aqueous solution (50%, 450 mg/ml) than from the neat solvent. Similarly penetration of ethoxyethanol was increased threefold in the presence of water (50%, 697 mg/ml). There was a corresponding increase in apparent permeability coefficient as the glycol ether concentration in water decreased. The maximum penetration rate of water also increased in the presence of both glycol ethers. Absorption through a synthetic membrane obeyed Fick's Law and absorption through rat skin showed a similar profile to human skin but with a lesser effect. The mechanisms for this phenomenon involves disruption of the stratum corneum lipid bilayer by desiccation by neat glycol ether micelles, hydration with water mixtures and the physicochemical properties of the glycol ether-water mixtures. Full elucidation of the profile of absorption of glycol ethers from mixtures is required for risk assessment of dermal exposure. This work supports the view that risk assessments for dermal contact scenarios should ideally be based on absorption data obtained for the relevant formulation or mixture and exposure scenario and that absorption derived from permeability coefficients may be inappropriate for water-miscible solvents.

  18. Two-photon interband absorption coefficients in tungstate and molybdate crystals

    NASA Astrophysics Data System (ADS)

    Lukanin, V. I.; Karasik, A. Ya.

    2015-02-01

    Two-photon absorption (TPA) coefficients were measured in tungstate and molybdate crystals - BaWO4, KGW, CaMoO4, BaMoO4, CaWO4, PbWO4 and ZnWO4 upon different orientations of excitation polarization with respect to the crystallographic axes. Trains of 25 ps pulses with variable radiation intensities of third (349 nm) harmonics of passively mode-locked 1047 nm Nd:YLF laser were used for interband two-photon excitation of the crystals. It was suggested that in the case, when 349 nm radiation pumping energy exceeds the bandgap width (h?>Eg), the nonlinear excitation process can be considered as two-step absorption. The interband two-photon absorption in all the studied crystals induces the following one-photon absorption from the exited states, which affects the nonlinear process dynamics and leads to a hysteresis in the dependence of the transmission on the excitation intensity. This fact was taken into account under analysis of the experimental dependences of the reciprocal transmission on the excitation intensity. Laser excitation in the transparency region of the crystals caused stimulated Raman scattering (SRS) not for all the crystals studied. The measured nonlinear coefficients allowed us to explain the suppression of SRS in crystals as a result of competition between the SRS and TPA.

  19. Atmospheric absorption of terahertz radiation and water vapor continuum effects

    E-print Network

    Massachusetts at Lowell, University of

    Atmospheric absorption of terahertz radiation and water vapor continuum effects David M. Slocum a April 2013 Keywords: Water vapor Absorption Continuum Terahertz Spectroscopy a b s t r a c t The water vapor continuum absorption spectrum was investigated using Fourier Trans- form Spectroscopy

  20. Condensation coefficient of water in a weak condensation state

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kazumichi; Watanabe, Shunsuke; Yamano, Daigo; Yano, Takeru; Fujikawa, Shigeo

    2008-07-01

    The condensation coefficient of water at a vapor-liquid interface is determined by combining shock tube experiments and numerical simulations of the Gaussian-BGK Boltzmann equation. The time evolution in thickness of a liquid film, which is formed on the shock tube endwall behind the shock wave reflected at the endwall, is measured with an optical interferometer consisting of the physical beam and the reference one. The reference beam is utilized to eliminate systematic noises from the physical beam. The growth rate of the film is evaluated from the measured time evolution and it is incorporated into the kinetic boundary condition for the Boltzmann equation. From a numerical simulation using the boundary condition, the condensation coefficient of water is uniquely deduced. The results show that, in a condition of weak condensation near a vapor-liquid equilibrium state, the condensation coefficient of water is almost equal to the evaporation coefficient estimated by molecular dynamics simulations near a vapor-liquid equilibrium state and it decreases as the system becomes a nonequilibrium state. The condensation coefficient of water is nearly identical with that of methanol [Mikami, S., Kobayashi, K., Ota, T., Fujikawa, S., Yano, T., Ichijo, M., 2006. Molecular gas dynamics approaches to interfacial phenomena accompanied with condensation. Exp. Therm. Fluid Sci. 30, 795-800].

  1. Backscatter factors and mass energy-absorption coefficient ratios for diagnostic radiology dosimetry

    NASA Astrophysics Data System (ADS)

    Benmakhlouf, Hamza; Bouchard, Hugo; Fransson, Annette; Andreo, Pedro

    2011-11-01

    Backscatter factors, B, and mass energy-absorption coefficient ratios, (?en/?)w, air, for the determination of the surface dose in diagnostic radiology were calculated using Monte Carlo simulations. The main purpose was to extend the range of available data to qualities used in modern x-ray techniques, particularly for interventional radiology. A comprehensive database for mono-energetic photons between 4 and 150 keV and different field sizes was created for a 15 cm thick water phantom. Backscattered spectra were calculated with the PENELOPE Monte Carlo system, scoring track-length fluence differential in energy with negligible statistical uncertainty; using the Monte Carlo computed spectra, B factors and (?en/?)w, air were then calculated numerically for each energy. Weighted averaging procedures were subsequently used to convolve incident clinical spectra with mono-energetic data. The method was benchmarked against full Monte Carlo calculations of incident clinical spectra obtaining differences within 0.3-0.6%. The technique used enables the calculation of B and (?en/?)w, air for any incident spectrum without further time-consuming Monte Carlo simulations. The adequacy of the extended dosimetry data to a broader range of clinical qualities than those currently available, while keeping consistency with existing data, was confirmed through detailed comparisons. Mono-energetic and spectra-averaged values were compared with published data, including those in ICRU Report 74 and IAEA TRS-457, finding average differences of 0.6%. Results are provided in comprehensive tables appropriated for clinical use. Additional qualities can easily be calculated using a designed GUI interface in conjunction with software to generate incident photon spectra.

  2. Estimation of octanol/water partition coefficients using LSER parameters

    USGS Publications Warehouse

    Luehrs, Dean C.; Hickey, James P.; Godbole, Kalpana A.; Rogers, Tony N.

    1998-01-01

    The logarithms of octanol/water partition coefficients, logKow, were regressed against the linear solvation energy relationship (LSER) parameters for a training set of 981 diverse organic chemicals. The standard deviation for logKow was 0.49. The regression equation was then used to estimate logKow for a test of 146 chemicals which included pesticides and other diverse polyfunctional compounds. Thus the octanol/water partition coefficient may be estimated by LSER parameters without elaborate software but only moderate accuracy should be expected.

  3. On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Andreo, Pedro; Burns, David T.; Salvat, Francesc

    2012-04-01

    A systematic analysis of the available data has been carried out for mass energy-absorption coefficients and their ratios for air, graphite and water for photon energies between 1 keV and 2 MeV, using representative kilovoltage x-ray spectra for mammography and diagnostic radiology below 100 kV, and for 192Ir and 60Co gamma-ray spectra. The aim of this work was to establish ‘an envelope of uncertainty’ based on the spread of the available data. Type A uncertainties were determined from the results of Monte Carlo (MC) calculations with the PENELOPE and EGSnrc systems, yielding mean values for µen/? with a given statistical standard uncertainty. Type B estimates were based on two groupings. The first grouping consisted of MC calculations based on a similar implementation but using different data and/or approximations. The second grouping was formed by various datasets, obtained by different authors or methods using the same or different basic data, and with different implementations (analytical, MC-based, or a combination of the two); these datasets were the compilations of NIST, Hubbell, Johns-Cunningham, Attix and Higgins, plus MC calculations with PENELOPE and EGSnrc. The combined standard uncertainty, uc, for the µen/? values for the mammography x-ray spectra is 2.5%, decreasing gradually to 1.6% for kilovoltage x-ray spectra up to 100 kV. For 60Co and 192Ir, uc is approximately 0.1%. The Type B uncertainty analysis for the ratios of µen/? values includes four methods of analysis and concludes that for the present data the assumption that the data interval represents 95% confidence limits is a good compromise. For the mammography x-ray spectra, the combined standard uncertainties of (µen/?)graphite,air and (µen/?)graphite,water are 1.5%, and 0.5% for (µen/?)water,air, decreasing gradually down to uc = 0.1% for the three µen/? ratios for the gamma-ray spectra. The present estimates are shown to coincide well with those of Hubbell (1977 Rad. Res. 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (µen/?)graphite,air for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication).

  4. On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry.

    PubMed

    Andreo, Pedro; Burns, David T; Salvat, Francesc

    2012-04-21

    A systematic analysis of the available data has been carried out for mass energy-absorption coefficients and their ratios for air, graphite and water for photon energies between 1 keV and 2 MeV, using representative kilovoltage x-ray spectra for mammography and diagnostic radiology below 100 kV, and for ¹?²Ir and ??Co gamma-ray spectra. The aim of this work was to establish 'an envelope of uncertainty' based on the spread of the available data. Type A uncertainties were determined from the results of Monte Carlo (MC) calculations with the PENELOPE and EGSnrc systems, yielding mean values for µ(en)/? with a given statistical standard uncertainty. Type B estimates were based on two groupings. The first grouping consisted of MC calculations based on a similar implementation but using different data and/or approximations. The second grouping was formed by various datasets, obtained by different authors or methods using the same or different basic data, and with different implementations (analytical, MC-based, or a combination of the two); these datasets were the compilations of NIST, Hubbell, Johns-Cunningham, Attix and Higgins, plus MC calculations with PENELOPE and EGSnrc. The combined standard uncertainty, u(c), for the µ(en)/? values for the mammography x-ray spectra is 2.5%, decreasing gradually to 1.6% for kilovoltage x-ray spectra up to 100 kV. For ??Co and ¹?²Ir, u(c) is approximately 0.1%. The Type B uncertainty analysis for the ratios of µ(en)/? values includes four methods of analysis and concludes that for the present data the assumption that the data interval represents 95% confidence limits is a good compromise. For the mammography x-ray spectra, the combined standard uncertainties of (µ(en)/?)(graphite,air) and (µ(en)/?)(graphite,water) are 1.5%, and 0.5% for (µ(en)/?)(water,air), decreasing gradually down to u(c) = 0.1% for the three µ(en)/? ratios for the gamma-ray spectra. The present estimates are shown to coincide well with those of Hubbell (1977 Rad. Res. 70 58-81), except for the lowest energy range (radiodiagnostic) where it is concluded that current databases and their systematic analysis represent an improvement over the older Hubbell estimations. The results for (µ(en)/?)(graphite,air) for the gamma-ray dosimetry range are moderately higher than those of Seltzer and Bergstrom (2005 private communication). PMID:22451262

  5. Absorption

    NSDL National Science Digital Library

    Katie Hale (CSUF; )

    2002-09-26

    The process of absorption is a cellular process (microscopic). Absorption cells line the stomach and intestine walls and allow small nutrients (broken down from the food we eat) to pass through and into our blood. The process of absorption is much like a leaking balloon filled with water. The balloon is the stomach or intestine, the tiny holes are the absorption cells, and the water is nutrients leaving.

  6. Diffusion coefficient and shear viscosity of rigid water models.

    PubMed

    Tazi, Sami; Bo?an, Alexandru; Salanne, Mathieu; Marry, Virginie; Turq, Pierre; Rotenberg, Benjamin

    2012-07-18

    We report the diffusion coefficient and viscosity of popular rigid water models: two non-polarizable ones (SPC/E with three sites, and TIP4P/2005 with four sites) and a polarizable one (Dang-Chang, four sites). We exploit the dependence of the diffusion coefficient on the system size (Yeh and Hummer 2004 J. Phys. Chem. B 108 15873) to obtain the size-independent value. This also provides an estimate of the viscosity of all water models, which we compare to the Green-Kubo result. In all cases, a good agreement is found. The TIP4P/2005 model is in better agreement with the experimental data for both diffusion and viscosity. The SPC/E and Dang-Chang models overestimate the diffusion coefficient and underestimate the viscosity. PMID:22739097

  7. Diffusion coefficient and shear viscosity of rigid water models

    NASA Astrophysics Data System (ADS)

    Tazi, Sami; Bo?an, Alexandru; Salanne, Mathieu; Marry, Virginie; Turq, Pierre; Rotenberg, Benjamin

    2012-07-01

    We report the diffusion coefficient and viscosity of popular rigid water models: two non-polarizable ones (SPC/E with three sites, and TIP4P/2005 with four sites) and a polarizable one (Dang-Chang, four sites). We exploit the dependence of the diffusion coefficient on the system size (Yeh and Hummer 2004 J. Phys. Chem. B 108 15873) to obtain the size-independent value. This also provides an estimate of the viscosity of all water models, which we compare to the Green-Kubo result. In all cases, a good agreement is found. The TIP4P/2005 model is in better agreement with the experimental data for both diffusion and viscosity. The SPC/E and Dang-Chang models overestimate the diffusion coefficient and underestimate the viscosity.

  8. Spectroscopic method for determination of the absorption coefficient in brain tissue

    NASA Astrophysics Data System (ADS)

    Johansson, Johannes D.

    2010-09-01

    I use Monte Carlo simulations and phantom measurements to characterize a probe with adjacent optical fibres for diffuse reflectance spectroscopy during stereotactic surgery in the brain. Simulations and measurements have been fitted to a modified Beer-Lambert model for light transport in order to be able to quantify chromophore content based on clinically measured spectra in brain tissue. It was found that it is important to take the impact of the light absorption into account when calculating the apparent optical path length, lp, for the photons in order to get good estimates of the absorption coefficient, ?a. The optical path length was found to be well fitted to the equation lp=a+b ln(Is)+c ln(?a)+d ln(Is)ln(?a), where Is is the reflected light intensity for scattering alone (i.e., zero absorption). Although coefficients a-d calculated in this study are specific to the probe used here, the general form of the equation should be applicable to similar probes.

  9. Predicting Soil-Water Partition Coefficients for Cadmium

    E-print Network

    Sparks, Donald L.

    understand the mechanism of adsorption, the experimental results for the adsorption of Cd by the 15 soils with natural soil particles is complex, involving multiple mechanisms. Much of the work relating to trace metalPredicting Soil-Water Partition Coefficients for Cadmium S U E N - Z O N E L E E Department

  10. A consecutive reconstruction strategy for estimating absorption and scattering coefficient distribution in multiple-illumination photoacoustic tomography (MIPAT)

    NASA Astrophysics Data System (ADS)

    Shao, Peng; Harrison, Tyler J.; Zemp, Roger J.

    2014-03-01

    Quantitative photoacoustic microscopy (qPAT) is challenging. We present an algorithm which consecutively reconstructs absorption and scattering coefficient distributions with an iterative scheme in multiple-illumination photoacoustic tomography (MIPAT). In each iteration, the absorption distribution is estimated with the least-squares fixed-point iteration method. Then the diffusion coefficient is estimated with an updated version of optical fluence based on the previously modified absorption information. This procedure is repeated till an acceptable results is achieved. Simulation examples demonstrate the capability of this method in faithfully recovering the absorption and diffusion coeffient distributions, and fast convergence.

  11. Non-uniform sound intensity distributions when measuring absorption coefficients in reverberation chambers using a phased beam tracing.

    PubMed

    Jeong, Cheol-Ho

    2010-06-01

    Measured absorption coefficients in reverberation chambers often differ from theoretical random incidence absorption coefficients, because ideal assumptions for the theoretical random incidence absorption coefficient are not fulfilled during measurements in actual reverberation chambers. Therefore sound intensity distributions on absorber under measurement conditions have been simulated using a phased beam tracing, and used as correction functions for reducing discrepancies between the measured and theoretical absorption coefficients. Two reverberation rooms were investigated by assuming that a test specimen was attached to a vertical surface and the floor. The frequency-dependent sound intensity distributions on absorbers were found to be affected by the reverberation chamber geometry and dimensions, the absorption capability of the specimen, and the placement of the specimen. High frequency intensity distributions above 1 kHz were similar for all studied cases, but some variations in low frequency intensity distributions were observed. If the non-uniform intensity distribution and a finite size effect are taken into account for correcting the theoretical absorption coefficients, a good agreement is found between corrected and measured statistical absorption coefficients. The non-uniform sound intensity can account for the discrepancy at high frequencies. PMID:20550256

  12. Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Courtin, Regis

    1988-08-01

    The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.

  13. Pressure-induced absorption coefficients for radiative transfer calculations in Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Courtin, Regis

    1988-01-01

    The semiempirical theory of Birnbaum and Cohen (1976) is used to calculate the FIR pressure-induced absorption (PIA) spectra of N2, CH4, N2 + Ar, N2 + CH4, and N2 + H2 under conditions like those in the Titan troposphere. The results are presented graphically and compared with published data from laboratory measurements of PIA in the same gases and mixtures (Dagg et al., 1986; Dore et al., 1986). Good agreement is obtained, with only a slight underestimation of PIA at 300-400/cm in the case of CH4. The absorption coefficients are presented in tables, and it is suggested that the present findings are of value for evaluating the effects of tropospheric clouds on the Titan FIR spectrum and studying the greenhouse effect near the Titan surface.

  14. The effective air absorption coefficient for predicting reverberation time in full octave bands.

    PubMed

    Wenmaekers, R H C; Hak, C C J M; Hornikx, M C J

    2014-12-01

    A substantial amount of research has been devoted to producing a calculation model for air absorption for pure tones. However, most statistical and geometrical room acoustic prediction models calculate the reverberation time in full octave bands in accordance with ISO 3382-1 (International Organization for Standardization, 2009). So far, the available methods that allow calculation of air absorption in octave bands have not been investigated for room acoustic applications. In this paper, the effect of air absorption on octave band reverberation time calculations is investigated based on calculations. It is found that the approximation method, as described in the standard ANSI S1.26 (American National Standards Institute, 1995), fails to estimate accurate decay curves for full octave bands. In this paper, a method is used to calculate the energy decay curve in rooms based on a summation of pure tones within the band. From this decay curve, which is found to be slightly concave upwards, T20 and T30 can be determined. For different conditions, an effective intensity attenuation coefficient mB ;eff for the full octave bands has been calculated. This mB ;eff can be used for reverberation time calculations, if results are to be compared with T20 or T30 measurements. Also, guidelines are given for the air absorption correction of decay curves, measured in a scale model. PMID:25480055

  15. Uncertainty analysis of standardized measurements of random-incidence absorption and scattering coefficients.

    PubMed

    Müller-Trapet, Markus; Vorländer, Michael

    2015-01-01

    This work presents an analysis of the effect of some uncertainties encountered when measuring absorption or scattering coefficients in the reverberation chamber according to International Organization for Standardization/American Society for Testing and Materials standards. This especially relates to the uncertainty due to spatial fluctuations of the sound field. By analyzing the mathematical definition of the respective coefficient, a relationship between the properties of the chamber and the test specimen and the uncertainty in the measured quantity is determined and analyzed. The validation of the established equations is presented through comparisons with measurement data. This study analytically explains the main sources of error and provides a method to obtain the product of the necessary minimum number of measurement positions and the band center frequency to achieve a given maximum uncertainty in the desired quantity. It is shown that this number depends on the ratio of room volume to sample surface area and the reverberation time of the empty chamber. PMID:25618039

  16. Accurate value for the absorption coefficient of silicon at 633 nm

    SciTech Connect

    Geist, J.; Schaefer, A.R.; Song, J.F.; Wang, Y.H.; Zalewski, E.F.

    1990-01-01

    High-accuracy transmission measurements at an optical wavelength of 633 nm and mechanical measurements of the thickness of a 13 micrometer thick silicon-crystal film have been used to calculate the absorption and extinction coefficients of silicon at 633 nm. The results are 3105 + or - 62/cm and 0.01564 + or - 0.00031, respectively. These results are about 15% less than current handbook data for the same quantities, but are in good agreement with a recent fit to one set of data described in the literature.

  17. Is the permeability coefficient Kp a reliable tool in percutaneous absorption studies?

    PubMed

    Korinth, Gintautas; Schaller, Karl Heinz; Drexler, Hans

    2005-03-01

    In percutaneous absorption studies the potency of penetration of chemical substances is often described by the permeability coefficient Kp. The experimentally determined Kp is characterized according to Fick's first law of diffusion by the ratio of flux and the concentration of the test compound (Kp=Flux/C). This equation implies that in percutaneous absorption studies Kp is theoretically a more reliable parameter than flux taking the concentration into consideration, and should remain constant for each compound independent from the grade of dilution. In our study we evaluated the course of the percutaneous absorption parameters flux and Kp of neat and of 50% aqueous solution of 2-butoxyethanol (BE). An infinite dose of neat and 50% aqueous solution of non-radiolabeled BE were applied on excised human skin from two donors in static diffusion cells in parallel (for each test setting n=21). The flux of 50% aqueous BE (0.704+/-0.152 mg/cm2/h) was about 15-fold higher than that of neat BE (0.045+/-0.014 mg/cm2/h). The comparison of the Kp values of both test settings showed with a factor of about 31 (Kp=1.563 x 10(-3) cm/h) much higher values for 50% aqueous BE and Kp=0.050 x 10(-3) cm/h for neat BE. Although the flux does not consider the chemical concentration, it showed a smaller difference in both test settings as Kp; however, the flux remains a non-specific parameter for the description of percutaneous absorption. The results of our experiments showed that the permeability coefficient Kp was not able to adjust the flux of BE to the concentration. This is in agreement with the evaluation of Kp from BE data described in the literature. PMID:15627196

  18. Theoretical calculations of nonlinear refraction and absorption coefficients of doped graphene

    NASA Astrophysics Data System (ADS)

    Margulis, Vl A.; Muryumin, E. E.; Gaiduk, E. A.

    2014-12-01

    In this study, we present the first theoretical predictions concerning the nonlinear refractive and absorptive properties of the doped graphene in which the Fermi energy {{E}F} of charge carriers (noninteracting massless Dirac fermions) is controlled by an external gate voltage. We base our study on the original perturbation theory technique developed by Genkin and Mednis (1968 Sov. Phys. JETP 27 609) for calculating the nonlinear-optical (NLO) response coefficients of bulk crystalline semiconductors with partially filled bands. Using a simple tight-binding model for the ?-electron energy bands of graphene, we obtain analytic expressions for the nonlinear refractive index {{n}2}(? ) and the nonlinear absorption coefficient {{? }2}(? ) of the doped graphene at photon energies above twice the value of the Fermi energy (\\hbar ? \\gt 2{{E}F}). We show that in this spectral region, both the nonlinear refraction ant the nonlinear absorption are determined predominantly by the combined processes which simultaneously involve intraband and interband motion of ?-electrons. Our calculations indicate that extremely large negative values of n2 (of the order of -{{10}-6} cm2 W?1) can be achieved in the graphene at a relatively low doping level (of about 1012 cm?2) provided that the excitation frequency slightly exceeds the threshold frequency corresponding to the onset of interband transitions. With a further increase of the radiation frequency, the {{n}2}(? ) becomes positive and begins to decrease in its absolute magnitude. The peculiar frequency dispersion of n2 and a negative sign of the {{? }2} (absorption bleaching), as predicted by our theory, suggest that the doped graphene is a prospective NLO material to be used in practical optical switching applications.

  19. Temperature and pressure dependence of dichloro-difluoromethane (CF2C12) absorption coefficients for CO2 waveguide laser radiation

    NASA Technical Reports Server (NTRS)

    Harward, C. N.

    1977-01-01

    Measurements were performed to determine the pressure and temperature dependence of CFM-12 absorption coefficients for CO2 waveguide laser radiation. The absorption coefficients of CFM-12 for CO2 waveguide laser radiation were found to have no spectral structure within small spectral bandwidths around the CO2 waveguide laser lines in the CO2 spectral band for pressures above 20 torr. All of the absorption coefficients for the CO2 laser lines studied are independent of pressure above 100 torr, except for the P(36) laser CO2 spectral band. The absorption coefficients associated with the P(42) line in the same band showed the greatest change with temperature, and it also has the largest value of all the lines studied.

  20. Modeling of marine light absorption and ocean color: Partitioning of total and particulate absorption coefficients and evaluation of an inverse reflectance algorithm

    NASA Astrophysics Data System (ADS)

    Zheng, Guangming

    Partitioning of the total non-water absorption coefficient of seawater, anw(lambda), into phytoplankton, aph(lambda), and non-phytoplankton, adg(lambda), components is important to research in ocean optics, biology, and biogeochemistry. I developed a partitioning model based on stacked-constraints approach, which requires weakly restrictive assumptions about the spectral slope of adg(lambda) and the spectral shape of a ph(lambda). With a comprehensive set of inequality constraints, the model first derives a wide range of speculative solutions for adg(lambda) and aph(lambda) and then identifies feasible solutions. Final model outputs include the optimal solutions that agree well with measurements (with biases typically within +/-5%), and a range of feasible solutions that encompasses the measured adg(lambda) and a ph(lambda) with a probability > 90% at most wavelengths. I also developed another model for partitioning the spectral absorption coefficient of suspended marine particles, ap(lambda), into phytoplankton, aph(lambda), and non-algal, ad(lambda), components based on the stacked-constraints approach. Partitioning results of the model generally agree well with measurements and are superior in terms of error statistics compared with previous partitioning models. These results support the prospect for the applications of the partitioning models using the input data of anw(lambda) and ap(lambda) collected from various oceanographic and remote-sensing platforms. I also evaluated the performance of the Quasi-Analytical Algorithm (QAA) for deriving the spectral total absorption, a(lambda), and backscattering, bb(lambda), coefficients of seawater from input spectrum of remote-sensing reflectance, Rrs(lambda), using field data collected in the Arctic and lower-latitude open waters. The performance of QAA for estimating a(lambda) varies from very good to fair (bias on the order of +/-10%) depending on light wavelength and the oceanic region. For bb(lambda), the QAA typically shows overestimation from small to as large as about 35%. A sensitivity analysis shows that the parameter u [? bb/(a+bb)] at the reference wavelength of 555 nm generally contributes the most significant bias to bb(lambda) at all wavelengths within the spectrum of visible light, whereas the interplay between u(555) and u(lambda) generally dominates the errors of QAA-derived a(lambda) except for the reference wavelength. Our findings provide guidance for future efforts towards refinement of the QAA and potentially also development of other inverse models.

  1. Detectability of Absorption and Reduced Scattering Coefficients in Frequency-Domain Measurements Using a Realistic Head Phantom

    PubMed Central

    Zhang, Xiaofeng; Webb, Andrew

    2013-01-01

    Detection limits of the changes in absorption and reduced scattering coefficients were investigated using a frequency-domain near-infrared system in a realistic head phantom. The results were quantified in terms of the maximum detectable depth for different activation volumes in the range of 0.8–20 microliters. The non-linear relation between the maximum detectable depth and the magnitude of changes in the absorption coefficient conform well with the Born approximation to the diffusion equation. The minimal detectable changes in the reduced scattering coefficient measured in terms of the phase signal were found to be approximately twice as large as that of the absorption coefficient using the AC signal for the same volume and at the same depth. The phase delay, which can be used to quantify the fast neuronal optical response in the human brain, showed a linear dependence on the reciprocal of the reduced scattering coefficient, as predicted by the Rytov approximation. PMID:23262479

  2. The impact of the coefficient of absorption of solar radiation on the state of stress in heterogeneous masonry

    NASA Astrophysics Data System (ADS)

    Beran, Pavel

    2013-10-01

    The masonry is heterogeneous material created from stones and mortar. The material characteristics of masonry components may differ in many aspects. The intention of this paper is the description of the thermal stresses which are generated by different values of coefficient of solar radiation absorption. The results were obtained by means of the 3-D finite element model of masonry. The difference of absorption coefficient between stone and mortar may cause increase of pressure thermal stress.

  3. Inherent optical properties of the ocean: retrieval of the absorption coefficient of chromophoric dissolved organic matter from airborne laser spectral fluorescence measurements.

    PubMed

    Hoge, F E; Vodacek, A; Swift, R N; Yungel, J K; Blough, N V

    1995-10-20

    The absorption coefficient of chromophoric dissolved organic matter (CDOM) at 355 nm has been retrieved from airborne laser-induced and water Raman-normalized CDOM fluorescence. Four combined airborne and ship field experiments have demonstrated that (1) the airborne CDOM fluorescence-to--water Raman ratio is linearly related to concurrent quinine-sulfate-standardized CDOM shipboard fluorescence measurements over a wide range of water masses (coastal to blue water); (2) the vicarious calibration of the airborne fluorosensor in units traceable to a fluorescence standard can be established and then maintained over an extended time period by tungsten lamp calibration; (3) the vicariously calibrated airborne CDOM fluorescence-to-water Raman ratio can be directly applied to previously developed shipboard fluorescence-to-absorption algorithms to retrieve CDOM absorption; and (4) the retrieval is not significantly affected by long-path multiple scattering, differences in attenuation at the excitation and emission wavelengths, or measurement in the 180° backscatter configuration. Airborne CDOM absorption measurements will find immediate application to (a) forward and inverse modeling of oceanic water-leaving radiance and (b) validation of satellite-retrieved products such as CDOM absorption. PMID:21060564

  4. Crop coefficient, yield response to water stress and water productivity of teff ( Eragrostis tef (Zucc.)

    Microsoft Academic Search

    A. Araya; Leo Stroosnijder; G. Girmay; S. D. Keesstra

    2011-01-01

    In the semi-arid region of Tigray, Northen Ethiopia a two season experiment was conducted to measure evapotranspiration, estimate yield response to water stress and derive the crop coefficient of teff using the single crop coefficient approach with simple, locally made lysimeters and field plots. During the experiment we also estimated the water productivity of teff taking into account long-term rainfall

  5. Mass-specific light absorption coefficients of natural aquatic particles in the near-infrared spectral region

    E-print Network

    Mass-specific light absorption coefficients of natural aquatic particles in the near-infrared Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland Abstract The extent of light absorption in the near-infrared spectral region (NIR; 700­900 nm) of natural suspended particles was investigated

  6. Image reconstruction of the absorption coefficients with l1-norm minimization from photoacoustic measurements

    PubMed Central

    Hirasawa, Takeshi; Kushibiki, Toshihiro; Ishihara, Miya

    2015-01-01

    Background The photoacoustic (PA) imaging by considering light propagation into image reconstruction process can provide quantitative information of photon absorbers, such as hemoglobin and exogenous dyes, and to improve their imaging contrasts. Methods A 2D image reconstruction of the distribution of the light absorption coefficient from the PA measurements with light source and ultrasound transducer placed at the identical position was tested. The PA pressures were formulated with the PA wave equation and the photon diffusion equation. The relation between the PA pressure and the absorption coefficient was linearized. The image reconstruction was carried out by minimizing the squared error between the measured and calculated PA signals. The l1-norm of the reconstructed image was simultaneously minimized to improve the localization of the reconstructed target in the image. The image reconstruction with the l1-norm minimization was compared to that with the Tikhonov regularization by numerical simulation and phantom experiment. In phantom experiment, an aqueous solution of the intralipid and the indocyanine green was used as the measured object. The PA probe had optical fiber for illumination and piezoelectric film for detection placed at the identical position. Results The l1-norm minimization reconstructed more localized target than the Tikhonov regularization. Conclusions The l1-norm minimization is useful for the sparse PA image reconstruction. PMID:25694957

  7. Calculation of photon mass energy-transfer and mass energy-absorption coefficients.

    PubMed

    Seltzer, S M

    1993-11-01

    Calculations of mass energy-transfer and mass energy-absorption coefficients for photon energies from 1 keV to 100 MeV have been developed, based on a re-examination of the processes involved after the initial photon interaction. The probabilities for the initial interaction are from the current photon interaction cross-section database at the National Institute of Standards and Technology. The calculations then take into account (1) electron binding effects on the Compton-scattered photon distribution; (2) the complete cascade of fluorescence emission after ionization events in any atomic subshell, including those associated with incoherent scattering and triplet production; and (3) the radiative energy losses of the secondary electrons and positrons slowing down in the medium, including the emission of bremsstrahlung, characteristic X rays from impact ionization, and positron in-flight as well as at-rest annihilation quanta. Consideration of the processes in (3) goes beyond the continuous-slowing-down approximation and includes the effects of energy-loss straggling. Results for the mass energy-absorption coefficient are compared with those from recent tabulations. PMID:8248472

  8. Spectral absorption coefficients of argon and silicon and spectral reflectivity of aluminum

    NASA Technical Reports Server (NTRS)

    Krascella, N. L.

    1972-01-01

    A theoretical investigation was conducted to estimate the spectral properties of argon as a function of pressure, temperature, and wave number. The spectral characteristics of the argon buffer gas exert a strong influence on radiative energy transfer in the in-reactor test configuration of the nuclear light bulb engine. An existing computer program was modified and used to calculate the spectral absorption coefficients of argon at total pressures of 50, 100, 250, 500, 750 and 1000 atm in the temperature interval between 1000 and 30,000 K. At each pressure and temperature, spectral properties were calculated for forty-seven wave numbers in the interval between 1000 and 1,000,000 cm/1. Estimates of the spectral absorption coefficients of silicon were made as part of an evaluation of silicon vapor as a possible buffer-gas seeding agent for the reference nuclear light bulb engine. Existing cross-section data were used to calculate the spectral characteristics of silicon at twenty-four temperatures in the interval between 2000 and 10,000 K.

  9. Determination of attenuation coefficient for self-absorption correction in routine gamma ray spectrometry of environmental bulk sample

    Microsoft Academic Search

    K. Satoh; N. Ohashi; H. Higuchi; M. Noguchi

    1984-01-01

    A simple method to determine -ray attenuation coefficients using Ba-133 -rays has been developed and applied to self-absorption correction in routine -ray spectrometry for environmental samples composed of unknown matrix elements. Experimental values of the mass attenuation coefficient obtained by the method agree well with calculated values for samples of known elemental composition which was determined by means of chemical

  10. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  11. Absorption of water by thin, ionic films of gelatin.

    PubMed

    Fialkowski, M; Campbell, C J; Bensemann, I T; Grzybowski, B A

    2004-04-27

    This paper discusses absorption of water by thin, dry films of gelatin. Experiments using a wet-stamping technique were performed to characterize water uptake in terms of (i) equilibrium profiles of the water density inside the gel and (ii) the kinetics of water absorption. It was found that, in contrast to pure gelatin films, which absorb water approximately uniformly, films of gelatin doped with ionic additives have exponentially decaying equilibrium water profiles. The process of water absorption by both doped and undoped gels was described by a theoretical model based on the minimization of grand potential functional. The results of this model are in agreement with the experiment. PMID:15875375

  12. Separation methods for estimating octanol–water partition coefficients

    Microsoft Academic Search

    Salwa K Poole; Colin F Poole

    2003-01-01

    Separation methods for the indirect estimation of the octanol–water partition coefficient (logP) are reviewed with an emphasis on high throughput methods with a wide application range. The solvation parameter model is used to identify suitable separation systems for estimating logP in an efficient manner that negates the need for empirical trial and error experiments. With a few exceptions, systems based

  13. Octanol\\/water partition coefficients for environmentally important organic compounds

    Microsoft Academic Search

    Sylke Ritter; Werner H. Hauthal; Gerd Maurer

    1995-01-01

    Partition coefficients PO,w\\u000a (i) describing the distribution of a solute i onto coexisting phases of 1-octanol and water are needed in a large variety of\\u000a applications. They can be measured directly by HPLC as long as log PO,w\\u000a (i)? 3.5. For more hydrophobic substances, several experimental procedures have been proposed in the literature. The reliability\\u000a of those methods is questionable.

  14. Octanol-water partition coefficients of polychlorinated biphenyl congeners

    Microsoft Academic Search

    Darryl W. Hawker; Des W. Connell

    1988-01-01

    Octanol-water partition coefficients (K{sub OW}) for 13 polychlorinated biphenyl (PCB) congeners were accurately determined by the generator column technique. These values were used to confirm a highly significant linear relationship between log K{sub OW} and the logarithm of the relative retention time on a nonselective gas chromatographic stationary phase. The total surface areas (TSA) for all the PCB congeners were

  15. The melanosome: threshold temperature for explosive vaporization and internal absorption coefficient during pulsed laser irradiation.

    PubMed

    Jacques, S L; McAuliffe, D J

    1991-06-01

    The explosive vaporization of melanosomes in situ in skin during pulsed laser irradiation (pulse duration less than 1 microsecond) is observed as a visible whitening of the superficial epidermal layer due to stratum corneum disruption. In this study, the ruby laser (694 nm) was used to determine the threshold radiant exposure, H0 (J/cm2), required to elicit whitening for in vitro black (Negroid) human skin samples which were pre-equilibrated at an initial temperature, Ti, of 0, 20, or 50 degrees C. A plot of H0 vs Ti yields a straight line whose x-intercept indicates the threshold temperature of explosive vaporization to be 112 +/- 7 degrees C (SD, N = 3). The slope, delta H0/delta Ti, specifies the internal absorption coefficient, mua, within the melanosome: mua = -rho C/(slope(1 + 7.1 Rd)), where rho C is the product of density and specific heat, and Rd is the total diffuse reflectance from the skin. A summary of the absorption spectrum (mua) for the melanosome interior (351-1064 nm) is presented based on H0 data from this study and the literature. The in vivo absorption spectrum (380-820 nm) for human epidermal melanin was measured by an optical fiber spectrophotometer and is compared with the melanosome spectrum. PMID:1886936

  16. The Optical Absorption Coefficient of Bean Seeds Investigated Using Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sanchez-Hernandez, G.; Hernandez-Aguilar, C.; Dominguez-Pacheco, A.; Cruz-Orea, A.; Perez-Reyes, M. C. J.; Martinez, E. Moreno

    2014-05-01

    A knowledge about seed optical parameters is of great relevance in seed technology practice. Such parameters provide information about its absorption and reflectance, which could be useful for biostimulation processes, by light sources, in early stages of seed germination. In the present research photoacoustic spectroscopy (PAS) and the Rosencwaig and Gersho model were used to determine the optical absorption coefficient (? ) of five varieties of bean seeds (Phaseolus vulgaris L.), of different productive cycles; the seeds were biostimulated by laser treatment to evaluate the effects of biostimulation pre-sowing. It was found that the bean varieties V1, V2, V4, and V5 were optically opaque in the visible spectrum; in the case of the V3 variety, this sample was optically transparent from 680 nm. The varieties of the studied bean seeds showed significant statistical differences in sizes and also in their optical absorption spectra. The biostimulation effects showed that the seed samples with a higher optical penetration length had a positive biostimulation, in the percentage of germination, obtaining an enhancement of 47 % compared to the control sample. The utility of PAS for the optical characterization of seeds has been demonstrated in this study of the laser biostimulation process of this kind of samples.

  17. Octanol-water partition coefficient of glucose, sucrose, and trehalose.

    PubMed

    Mazzobre, María F; Román, María V; Mourelle, Ariel Feo; Corti, Horacio R

    2005-05-01

    The octanol-water partition coefficients (P) of glucose, sucrose, and trehalose were measured at temperatures between 5 and 20 degrees C using an enzymatic method. The measured log P is compared with calculated and experimental data previously reported. In the case of trehalose, the measured log P differs considerably from the theoretically estimated values and agrees with the expected value for a disaccharide. Some methods of assessing the partition coefficients are also analyzed and it is concluded that the atom/fragment contribution method overestimates the hydrophilicity of disaccharides and, probably in a larger extension, that of trisaccharides. The knowledge of P for these sugars is valuable both for basic or applied purposes, including food and biomolecules stabilization. PMID:15797137

  18. Remote Sensing of the Absorption Coefficients and Chlorophyll a Concentration in the U.S. Southern Middle Atlantic Bight from SeaWiFS and MODIS-Aqua

    NASA Technical Reports Server (NTRS)

    Pan, Xiaoju; Mannino, Antonio; Russ, Mary E.; Hooker, Stanford B.

    2008-01-01

    At present, satellite remote sensing of coastal water quality and constituent concentration is subject to large errors as compared to the capability of satellite sensors in oceanic waters. In this study, field measurements collected on a series of cruises within U.S. southern Middle Atlantic Bight (SMAB) were applied to improve retrievals of satellite ocean color products in order to examine the factors that regulate the bio-optical properties within the continental shelf waters of the SMAB. The first objective was to develop improvements in satellite retrievals of absorption coefficients of phytoplankton (a(sub ph)), colored dissolved organic matter (CDOM) (a(sub g)), non-pigmented particles (a(sub d)), and non-pigmented particles plus CDOM (a(sub dg)), and chlorophyll a concentration ([Chl_a]). Several algorithms were compared to derive constituent absorption coefficients from remote sensing reflectance (R(sub rs)) ratios. The validation match-ups showed that the mean absolute percent differences (MAPD) were typically less than 35%, although higher errors were found for a(sub d) retrievals. Seasonal and spatial variability of satellite-derived absorption coefficients and [Chl_a] was apparent and consistent with field data. CDOM is a major contributor to the bio-optical properties of the SMAB, accounting for 35-70% of total light absorption by particles plus CDOM at 443 nm, as compared to 30-45% for phytoplankton and 0-20% for non-pigmented particles. The overestimation of [Chl_a] from the operational satellite algorithms may be attributed to the strong CDOM absorption in this region. River discharge is important in controlling the bio-optical environment, but cannot explain all of the regional and seasonal variability of biogeochemical constituents in the SMAB.

  19. Study of the absorption coefficient of alpha particles to lower hybrid waves in tokamak

    SciTech Connect

    Wang, Jianbing, E-mail: zhangxm@ecust.edu.cn; Zhang, Xianmei, E-mail: zhangxm@ecust.edu.cn; Yu, Limin, E-mail: zhangxm@ecust.edu.cn; Zhao, Xiang, E-mail: zhangxm@ecust.edu.cn [Department of Physics, East China University of Science and Technology, P.O. Box 385, Shanghai 200237 (China)

    2014-02-12

    Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the ? particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient ?{sub ?} of LH waves due to ? particles. Results show that, the ?{sub ?} increases with the parallel refraction index n{sub ?} while deceases with increasing the frequency of LH waves ?{sub LH} over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?{sub ?} when n{sub e}?8×10{sup 19}m{sup ?3} for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, ? ? 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

  20. The influence of water mixtures on the dermal absorption of glycol ethers.

    PubMed

    Traynor, Matthew J; Wilkinson, Simon C; Williams, Faith M

    2007-01-15

    Glycol ethers are solvents widely used alone and as mixtures in industrial and household products. Some glycol ethers have been shown to have a range of toxic effects in humans following absorption and metabolism to their aldehyde and acid metabolites. This study assessed the influence of water mixtures on the dermal absorption of butoxyethanol and ethoxyethanol in vitro through human skin. Butoxyethanol penetrated human skin up to sixfold more rapidly from aqueous solution (50%, 450 mg/ml) than from the neat solvent. Similarly penetration of ethoxyethanol was increased threefold in the presence of water (50%, 697 mg/ml). There was a corresponding increase in apparent permeability coefficient as the glycol ether concentration in water decreased. The maximum penetration rate of water also increased in the presence of both glycol ethers. Absorption through a synthetic membrane obeyed Fick's Law and absorption through rat skin showed a similar profile to human skin but with a lesser effect. The mechanisms for this phenomenon involves disruption of the stratum corneum lipid bilayer by desiccation by neat glycol ether micelles, hydration with water mixtures and the physicochemical properties of the glycol ether-water mixtures. Full elucidation of the profile of absorption of glycol ethers from mixtures is required for risk assessment of dermal exposure. This work supports the view that risk assessments for dermal contact scenarios should ideally be based on absorption data obtained for the relevant formulation or mixture and exposure scenario and that absorption derived from permeability coefficients may be inappropriate for water-miscible solvents. PMID:17173944

  1. A reflectance spectra model of heavy metal stressed leaves: advances in the PROSPECT model adding specific absorption coefficients of heavy metal ion

    NASA Astrophysics Data System (ADS)

    Qu, Yonghua; Zhu, Yeqing; Ge, Xiaoli

    2014-03-01

    This article aims to investigate the reflectance model of heavy metal copper stressed crop. Forty-six groups of copper-treated leaves were measured during a laboratory experiment in order to obtain the leaf biochemical component information and its corresponding scanning electron microscopy image. Then a new reflectance spectral model was developed on the basis of the classical broadleaf radiative transfer model-PROSPECT. Comparing with the PROSPECT model, new models mainly consider adding specific absorption coefficient of copper ion. The scattering process is described by a refractive index (n) and a leaf structure parameter (N). Absorption is modeled using pigment concentration, water content, dry matter content, copper ion contamination and the corresponding specific spectral absorption coefficients (Kab, Kw, Kd, KCu). Thus, reflectance spectral modeling is an inversion procedure to calculate the above 6 parameters accurately. To validate the model 16 leaves were tested in laboratory experiment. This experiment showed that the inversion values of KCu had very strong agreement with the published absorption spectra of Cupric Chloride. The linear regression analysis between simulated and measured reflectance provides a correlation coefficient of 0.93 and a root mean squares of 0.067.

  2. Water absorption properties of ultrasonic treated brown rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To understand the effect of ultrasonic treated on brown rice, it is important to research the water absorption processing of brown rice before and after ultrasonic treatment. The objective of this study was investigate and modeling water absorption characteristics of brown rice using Peleg’s equatio...

  3. GASTROINTESTINAL ABSORPTION OF SOLUBLE URANIUM FROM DRINKING WATER

    EPA Science Inventory

    The manuscript describes results of an experiment to determine the gastrointestinal absorption of uranium from drinking water in 12 health adults. Most of the uranium ingested was excreted in feces in the first 2 days following ingestion of the water. The absorption was the same ...

  4. OCTANOL/WATER PARTITION COEFFICIENTS AND WATER SOLUBILITIES OF PHTHALATE ESTERS

    EPA Science Inventory

    Measurements of the octanol/water partition coefficients (K-ow) and water solubilities of di-n-octyl phthalate (DnOP) and di-n-decyl phthalate (DnDP) by the slow-stirring method are reported. The water solubility was also measured for di-n-hexyl phthalate (DnHP). The log K-ow val...

  5. Effect of water absorption on pollen adhesion.

    PubMed

    Lin, Haisheng; Lizarraga, Leonardo; Bottomley, Lawrence A; Carson Meredith, J

    2015-03-15

    Pollens possess a thin liquid coating, pollenkitt, which plays a major role in adhesion by forming capillary menisci at interfaces. Unfortunately, the influence of humidity on pollenkitt properties and capillary adhesion is unknown. Because humidity varies widely in the environment, the answers have important implications for better understanding plant reproduction, allergy and asthma, and pollen as atmospheric condensation nuclei. Here, pollenkitt-mediated adhesion of sunflower pollen to hydrophilic and hydrophobic surfaces was measured as a function of humidity. The results quantify for the first time the significant water absorption of pollenkitt and the resulting complex dependence of adhesion on humidity. On hydrophilic Si, adhesion increased with increasing RH for pollens with or without pollenkitt, up to 200nN at 70% RH. In contrast, on hydrophobic PS, adhesion of pollenkitt-free pollen is independent of RH. Surprisingly, when pollenkitt was present adhesion forces on hydrophobic PS first increased with RH up to a maximum value at 35% RH (?160nN), and then decreased with further increases in RH. Independent measurement of pollenkitt properties is used with models of capillary adhesion to show that humidity-dependent changes in pollenkitt wetting and viscosity are responsible for this complex adhesion behavior. PMID:25524008

  6. Modeling Infinite Dilution and Fickian Diffusion Coefficients of Carbon Dioxide in Water

    E-print Network

    Firoozabadi, Abbas

    Modeling Infinite Dilution and Fickian Diffusion Coefficients of Carbon Dioxide in Water J. Wambui infinite dilution diffusion coefficients for carbon dioxide and water mixtures. The model takes, carbon dioxide, classical thermodynamics Introduction The increase in atmospheric concentrations of CO2

  7. Absorption coefficient of aluminum near the critical point and the consequences on high-power nanosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Wu, Benxin; Shin, Yung C.

    2006-09-01

    During nanosecond laser ablation, the absorption coefficient determines the laser energy deposition in the target, the accurate knowledge of which near the material critical point is crucial for understanding the fundamental physics of high-power nanosecond laser ablation. In this letter, the absorption coefficient of aluminum near the critical point is calculated through the Drude model based on the measured electrical conductivity data, and its effect on laser ablation is investigated numerically using a heat transfer model. The result supports the experimental observations that phase explosion occurs for the ablation of aluminum by sufficiently intense laser pulses, and the model predicted phase explosion threshold is consistent with experimental measurements.

  8. Absorption coefficients for the 6190-A CH4 band between 290 and 100 K with application to Uranus' atmosphere

    NASA Technical Reports Server (NTRS)

    Smith, Wm. Hayden; Conner, Charles P.; Baines, Kevin H.

    1990-01-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH4 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum.

  9. Absorption coefficients for the 6190-A CH sub 4 band between 290 and 100 K with application to Uranus' atmosphere

    SciTech Connect

    Smith, WM.H.; Conner, C.P.; Baines, K.H. (Washington Univ., Saint Louis, MO (USA) JPL, Pasadena, CA (USA))

    1990-05-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH{sub 4} 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum. 18 refs.

  10. A correction of random incidence absorption coefficients for the angular distribution of acoustic energy under measurement conditions.

    PubMed

    Jeong, Cheol-Ho

    2009-04-01

    Most acoustic measurements are based on an assumption of ideal conditions. One such ideal condition is a diffuse and reverberant field. In practice, a perfectly diffuse sound field cannot be achieved in a reverberation chamber. Uneven incident energy density under measurement conditions can cause discrepancies between the measured value and the theoretical random incidence absorption coefficient. Therefore the angular distribution of the incident acoustic energy onto an absorber sample should be taken into account. The angular distribution of the incident energy density was simulated using the beam tracing method for various room shapes and source positions. The averaged angular distribution is found to be similar to a Gaussian distribution. As a result, an angle-weighted absorption coefficient was proposed by considering the angular energy distribution to improve the agreement between the theoretical absorption coefficient and the reverberation room measurement. The angle-weighted absorption coefficient, together with the size correction, agrees satisfactorily with the measured absorption data by the reverberation chamber method. At high frequencies and for large samples, the averaged weighting corresponds well with the measurement, whereas at low frequencies and for small panels, the relatively flat distribution agrees better. PMID:19354382

  11. Absorption refrigeration: cooling with hot water

    Microsoft Academic Search

    Rafferty

    1984-01-01

    The absorption cycle is a process by which refrigeration effect is produced through the use of two fluids and some quantity of heat input, rather than electrical input as in the more familiar vapor compression cycle. Both vapor compression and absorption refrigeration cycles accomplish the removal of heat through the evaporation of a refrigerant at a low pressure and the

  12. Absorption Coefficients of the Methane-Nitrogen Binary Ice System: Implications for Pluto

    NASA Astrophysics Data System (ADS)

    Protopapa, Silvia; Grundy, W.; Tegler, S.; Bergonio, J.; Boehnhardt, H.; Barrera, L.

    2013-10-01

    Near infrared spectroscopic measurements of Pluto display methane (CH4) ice absorption bands shifted toward shorter wavelengths compared to the central wavelengths of pure CH4 obtained in the laboratory. This shift, described by Schmitt and Quirico (1992), occurs when CH4 is dissolved at low concentrations in a matrix of solid N2, and the magnitude of the shift varies from one CH4 band to another. This is the main argument behind the modeling analysis of Pluto’s spectra available in literature, employing pure CH4 and CH4 diluted at low concentrations in N2. However, the nitrogen-methane binary phase diagram generated from X-ray diffraction studies by Prokhvatilov & Yantsevich (1983) indicates that at temperatures relevant to the surfaces of icy dwarf planets, like Pluto, two phases contribute to the absorptions: methane ice saturated with nitrogen and nitrogen ice saturated with methane. No optical constants are available so far for the latter component, limiting this way the knowledge of the methane-nitrogen mixing ratio across and into the surface of Pluto and other dwarf planets. New infrared absorption coefficient spectra of CH4-I diluted in ?-N2 and ?-N2 diluted in CH4-I were measured at temperatures between 40 and 90 K, in the wavelength range 0.8-2.5 ?m at different mixing ratios. The spectra were derived from transmission measurements of crystals grown from the liquid phase in closed cells. In particular, a systematic study of the changes in CH4:N2 mixtures spectral behavior with mixing ratio is presented for the first time, in order to understand whether the peak frequencies of the CH4-ice bands correlate with the amount of N2-ice. We report a linear trend of the blueshifts of the CH4-ice bands vs CH4 abundance. This trend varies from band to band, while it is fairly constant with temperature. These data are applied to interpret unpublished high dispersion H and K bands spectra of Pluto acquired with the NACO instrument at the ESO VLT on 27 June 2008. Acknowledgments: This work was supported in part by grant number NNX11AM53G from NASA's Outer Planets Research Program.

  13. ESTIMATION OF WATER SOLUBILITY AND OCTANOL/WATER PARTITION COEFFICIENT OF HYDROPHOBIC DYES - PART I. RELATIONSHIP BETWEEN SOLUBILITY AND PARTITION COEFFICIENT

    EPA Science Inventory

    Three regression approaches are examined for use in estimating water solubilities and octanol/water partition coefficients, two fundamental equilibrium constants that are widely used predicting the fate of organic chemicals in aquatic systems. pproaches examined are regression of...

  14. ABSORBANCE, ABSORPTION COEFFICIENT, AND APPARENT QUANTUM YIELD: A COMMENT ON AMBIGUITY IN THE USE OF THESE OPTICAL CONCEPTS

    EPA Science Inventory

    Several important optical terms such as "absorbance" and "absorption coefficient" are frequently used ambiguously in the current peer-reviewed literature. Since they are important terms that are required to derive other quantities such as the "apparent quantum yield" of photoprod...

  15. The effect of wafer stress on absorption coefficient and minority carrier diffusion length in cast poly-Si

    Microsoft Academic Search

    I. G. Hwang; D. K. Schroder; J. H. Wohlgemuth

    1993-01-01

    The surface photovoltage (SPV) technique is an attractive method for measuring the minority carrier diffusion length of solar cells. It has the advantage of not requiring permanent sample contacts. It does require, however, an accurate knowledge of the absorption coefficient-wavelength (?-?) relationship. This relationship is well known for single-crystal silicon and SPV plots are linear for such materials. However, for

  16. Linear absorption coefficient of beryllium in the 50-300-A wavelength range. [bandpass filter materials for ultraviolet astronomy instrumentation

    NASA Technical Reports Server (NTRS)

    Barstow, M. A.; Lewis, M.; Petre, R.

    1983-01-01

    Transmittances of thin-film filters fabricated for an extreme-UV astronomy sounding-rocket experiment yield values for the linear absorption coefficient of beryllium in the 50-300-A wavelength range, in which previous measurements are sparse. The inferred values are consistent with the lowest data previously published and may have important consequences for extreme-UV astronomers.

  17. Inverse bremsstrahlung absorption in large radiation fields during binary collisions-classical theory. II. Integrated rate coefficients for Coulomb collisions

    Microsoft Academic Search

    G J Pert

    1976-01-01

    For pt.I see ibid., vol.5, p.508 (1972). Integrated rate coefficients for the absorption of electromagnetic radiation in plasma when the plasma frequency is less than the radiation frequency are calculated from classical expressions derived earlier. The resulting formula is applicable over the complete range of field strengths. Numerical calculations are used to give useful interpolation formulae for the complete range

  18. PHOTOLUMINESCENT SIGNATURE OF ABSORBING MEDIUM WITH DEEP LEVELS BASED UPON ABSORPTION COEFFICIENTS DERIVED FROM PARABOLIC-BAND APPROXIMATIONS

    E-print Network

    Honsberg, Christiana

    PHOTOLUMINESCENT SIGNATURE OF ABSORBING MEDIUM WITH DEEP LEVELS BASED UPON ABSORPTION COEFFICIENTS@physics.usyd.edu.au ABSTRACT: This paper presents theoretical photoluminescent spectra of absorbing media each with valid consequences of multi-gap absorbers whose quantum states form parabolic bands. Photoluminescence spectroscopy

  19. Determination of soil–water sorption coefficients of volatile methylsiloxanes

    PubMed Central

    Kozerski, Gary E; Xu, Shihe; Miller, Julie; Durham, Jeremy

    2014-01-01

    The sorption behaviors of 4 cyclic and linear volatile methyl siloxane (VMS) compounds between water and organic matter in 3 United Kingdom soils were studied by a batch equilibrium method using13C-enriched sorbates. Sorption and desorption kinetics and isotherms were determined for octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), octamethyltrisiloxane (L3), and decamethyltetrasiloxane (L4). Concentrations of [13C]-VMS in the soil and aqueous phases were measured directly by extraction and gas chromatography–mass spectrometry techniques. All VMS compounds were sorbed rapidly, reaching constant distributions in all soils by 24?h. Desorption kinetics were very rapid, with reattainment of equilibrium within 1?h. In the main, linear isotherms were observed for aqueous concentrations at or below 4% of the solubility limits. The average sorption organic carbon partition coefficient (log?KOC) values across soils were 4.23 for D4, 5.17 for D5, 4.32 for L3, and 5.13 for L4, with standard deviations of 0.09 to 0.34. Desorption KOC values were systematically greater by 0.1 log units to 0.3 log units. The linear isotherms and low variation in KOC values across soils suggested partitioning-dominated sorption of the VMS. Compared with traditional hydrophobic organic compounds, KOC values for the VMS compounds were significantly lower than expected on the basis of their octanol–water partition coefficients. A linear free energy relationship analysis showed that these differences could be rationalized quantitatively in terms of the inherent characteristics of the VMS compounds, combined with the differences in solvation properties of organic matter and octanol. Environ Toxicol Chem 2014; 33:1937–1945. PMID:24862578

  20. Influence of plasma parameters on the absorption coefficient of alpha particles to lower hybrid waves in tokamaks

    SciTech Connect

    Wang, J.; Zhang, X., E-mail: zhangxm@ecust.edu.cn; Yu, L.; Zhao, X. [East China University of Science and Technology, Department of Physics (China)

    2014-12-15

    In tokamaks, fusion generated ? particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient ?{sub ?} of LH waves due to ? particles changing with some typical parameters is calculated in this paper. Results show that ?{sub ?} increases with the parallel refraction index n{sub ?}, while decreases with the frequency of LH waves ? over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient ?{sub ?} increases with n{sub e} when n{sub e} ? 8 × 10{sup 19} m{sup ?3}, while decreases with n{sub e} when n{sub e} becomes larger, and there is a peak value of ?{sub ?} when n{sub e} ? 8 × 10{sup 19} m{sup ?1} for the ITER-like scenario. The influence of spectral broadening in parametric decay instabilities on the absorption coefficient is evaluated. The value of ?{sub ?} with n{sub ?} being 2.5 is almost two times larger than that with n{sub ?} being 2.0 and is even lager in the case of 2.9, which will obviously increase the absorption of the LH power by alpha particles.

  1. Influence of plasma parameters on the absorption coefficient of alpha particles to lower hybrid waves in tokamaks

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zhang, X.; Yu, L.; Zhao, X.

    2014-12-01

    In tokamaks, fusion generated ? particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient ?? of LH waves due to ? particles changing with some typical parameters is calculated in this paper. Results show that ?? increases with the parallel refraction index n ?, while decreases with the frequency of LH waves ? over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient ?? increases with n e when n e ? 8 × 1019 m-3, while decreases with n e when n e becomes larger, and there is a peak value of ?? when n e ? 8 × 1019 m-1 for the ITER-like scenario. The influence of spectral broadening in parametric decay instabilities on the absorption coefficient is evaluated. The value of ?? with n ? being 2.5 is almost two times larger than that with n ? being 2.0 and is even lager in the case of 2.9, which will obviously increase the absorption of the LH power by alpha particles.

  2. Gas-film coefficients for the volatilization of ethylene dibromide from water

    USGS Publications Warehouse

    Rathbun, R.E.; Tal, D.Y.

    1986-01-01

    Gas-film coefficients for the volatilization of ethylene dibromide (EDB) and water were determined in the laboratory as a function of wind speed and temperature. The ratio of the coefficients was independent of wind speed and increased slightly with temperature. Use of this ratio with an environmentally determined gas-film coefficient for the evaporation of water permits determination of the gas-film coefficient for the volatilization of EDB from environmental waters.

  3. Effects of suspended sediment concentration on the absorption and scattering coefficients

    NASA Astrophysics Data System (ADS)

    Terrie, Gregory E.; Ladner, Sherwin; Gould, Richard A., Jr.

    1997-02-01

    The scattering coefficient (b) for the nearshore waters off the coast of North Carolina near Camp Lejeune is strongly influenced by suspended sediment concentration and total particulate cross-sectional area (xg). In-situ measurements of a and b were made using a WET Labs AC9 meter. Estimates of suspended sediment concentration and total particulate cross-sectional area were determined from laser particle size analyses of surface water samples. The SeaWiFS bio-optical algorithm was modified for Case II waters and used to estimate a and bb from remote sensing reflectance (Rrs). After conversion from backscattering (bb) to total scattering (b), modeled a and b values from the modified SeaWiFS algorithm were compared to the measured values. The differences between the measured and estimated values appear to be directly related to increases in suspended sediment concentration and xg. Correlations of about 0.90 were obtained for b vs xg and bb vs xg.

  4. Computation of the oscillator strength and absorption coefficients for the intersubband transitions of the spherical quantum dot

    NASA Astrophysics Data System (ADS)

    Özmen, Ayhan; Yakar, Yusuf; Çak?r, Bekir; Atav, Ülfet

    2009-10-01

    The electronic structure and optical properties of one-electron Quantum Dot (QD) with and without an on-center impurity were investigated by assuming a spherically symmetric confining potential of finite depth. The energy eigenvalues and the state functions of QD were calculated by using a combination of Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothan (HFR) method. We have calculated the binding energy for the states 1s,1p,1d,1f, oscillator strengths, the linear and third-order nonlinear optical absorption coefficients as a function of the incident photon energy and incident optical intensity for the 1s-1p, 1p-1d and 1d-1f transitions. The existence of the impurity has great influence on the optical absorption spectra and the oscillator strengths. Also we found that the magnitudes of the total absorption coefficients of the spherical QD increase for transitions between higher states.

  5. Determination of effective water vapor diffusion coefficient in pemfc gas diffusion layers

    E-print Network

    Kandlikar, Satish

    Determination of effective water vapor diffusion coefficient in pemfc gas diffusion layers Jacob M: Water vapor diffusion PEMFC Water management GDL Diffusivity MPL a b s t r a c t The primary removal, Determination of effective water vapor diffusion coefficient in pemfc gas diffusion layers, International

  6. Studies of Water Absorption Behavior of Plant Fibers at Different Temperatures

    NASA Astrophysics Data System (ADS)

    Saikia, Dip

    2010-05-01

    Moisture absorption of natural fiber plastic composites is one major concern in their outdoor applications. The absorbed moisture has many detrimental effects on the mechanical performance of these composites. A knowledge of the moisture diffusivity, permeability, and solubility is very much essential for the application of natural fibers as an excellent reinforcement in polymers. An effort has been made to study the water absorption behavior of some natural fibers such as bowstring hemp, okra, and betel nut at different temperatures to improve the long-term performance of composites reinforced with these fibers. The gain in moisture content in the fibers due to water absorption was measured as a function of exposure time at temperatures ranging from 300 K to 340 K. The thermodynamic parameters of the sorption process, such as diffusion coefficients and corresponding activation energies, were estimated.

  7. Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

    NASA Technical Reports Server (NTRS)

    Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

    2008-01-01

    Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

  8. A model for partitioning the light absorption coefficient of suspended marine particles into phytoplankton and nonalgal components

    NASA Astrophysics Data System (ADS)

    Zheng, Guangming; Stramski, Dariusz

    2013-06-01

    We developed a model for partitioning the spectral absorption coefficient of suspended marine particles, ap(?), into phytoplankton, aph(?), and nonalgal, ad(?), components based on the stacked-constraints approach. The key aspect of our model is the use of a set of inequality constraints that account for large variability in the aph(?) and ad(?) coefficients within the world's oceans. The bounds of inequality constraints were determined from the analysis of a comprehensive set of 505 field determinations of absorption coefficients in various oceanic environments. The feasible solutions of the model are found by simultaneously satisfying all inequality constraints. The optimal solutions represented by the median values of feasible solutions for aph(?) and ad(?) generally agree well with field measurements and are superior in terms of error statistics compared with previous partitioning models. For example, on the basis of comparisons of optimal model solutions with field determinations of absorption coefficients, the systematic error calculated as the median ratio of model-derived to measured values for both aph(443) and ad(443) is within ±1% for our model. The random error represented by the mean absolute percent difference for aph(443) and ad(443) is <5% and <20%, respectively. This study suggests that our model has the potential for successful applications with input data of ap(?) which can be collected from various oceanographic platforms.

  9. Absorptive removal of biomass tar using water and oily materials.

    PubMed

    Phuphuakrat, Thana; Namioka, Tomoaki; Yoshikawa, Kunio

    2011-01-01

    Water is the most common choice of absorption medium selected in many gasification systems. Because of poor solubility of tar in water, hydrophobic absorbents (diesel fuel, biodiesel fuel, vegetable oil, and engine oil) were studied on their absorption efficiency of biomass tar and compared with water. The results showed that only 31.8% of gravimetric tar was removed by the water scrubber, whereas the highest removal of gravimetric tar was obtained by a vegetable oil scrubber with a removal efficiency of 60.4%. When focusing on light PAH tar removal, the absorption efficiency can be ranked in the following order; diesel fuel>vegetable oil>biodiesel fuel>engine oil>water. On the other hand, an increase in gravimetric tar was observed for diesel fuel and biodiesel fuel scrubbers because of their easy evaporation. Therefore, the vegetable oil is recommended as the best absorbent to be used in gasification systems. PMID:20801021

  10. Bias in Dobson total ozone measurements at high latitudes due to approximations in calculations of ozone absorption coefficients and air mass

    Microsoft Academic Search

    G. Bernhard; R. D. Evans; G. J. Labow; S. J. Oltmans

    2005-01-01

    The Dobson spectrophotometer is the primary standard instrument for ground-based measurements of total column ozone. The accuracy of its data depends on the knowledge of ozone absorption coefficients used for data reduction. We document an error in the calculations that led to the set of absorption coefficients currently recommended by the World Meteorological Organisation (WMO). This error has little effect

  11. The absorption coefficient of the liquid N2 2.15-micron band and application to Triton

    NASA Technical Reports Server (NTRS)

    Grundy, William M.; Fink, Uwe

    1991-01-01

    The present measurements of the temperature dependence exhibited by the liquid N2 2.15-micron 2-0 collision-induced band's absorption coefficient and integrated absorption show the latter to be smaller than that of the N2 gas, and to decrease with decreasing temperature. Extrapolating this behavior to Triton's nominal surface temperature yields a new estimate of the N2-ice grain size on the Triton south polar cap; a mean N2 grain size of 0.7-3.0 cm is consistent with grain growth rate calculation results.

  12. Influence of the scattering and absorption coefficients on homogeneous room simulations that use a diffusion equation model.

    PubMed

    Navarro, Juan M; Escolano, José; Cobos, Maximo; López, José J

    2013-03-01

    The diffusion equation model was used for room acoustic simulations to predict the sound pressure level and the reverberation time. The technical literature states that the diffusion equation method accurately models the late portion of the room impulse response if the energy is sufficiently scattered. This work provides conclusions on the validity of the diffusion equation model for rooms with homogeneous dimensions in relation to the scattering coefficients of the boundaries. A systematic evaluation was conducted out to determine the ranges of the absorption and scattering coefficient values that result in low noticeable differences between the predictions from a geometrical acoustic model and those from the diffusion equation model. PMID:23463993

  13. Diffusion coefficients for hydrogen sulfide, carbon dioxide, and nitrous oxide in water over the temperature range 293--368 K

    SciTech Connect

    Tamimi, A.; Rinker, E.B.; Sandall, O.C. (Univ. of California, Santa Barbara, CA (United States). Chemical and Nuclear Engineering Dept.)

    1994-04-01

    Acid gases such as H[sub 2]S and CO[sub 2] are generally removed from natural gas, biogas, synthetic natural gas, and other process gas streams by means of absorption into aqueous alkanolamine solutions. A key parameter needed to model this diffusion with chemical reaction process in the liquid phase is the diffusion coefficient. A wetted-sphere absorption apparatus was used to measure the liquid-phase diffusion coefficients for hydrogen sulfide, carbon dioxide, and nitrous oxide over the temperature range 293--368 K. The experimental results obtained in this work are compared with values in the literature and with predictions from the Wilke-Chang equation. The data presented here extend the temperature range of reported diffusivities for these gases in water.

  14. Experimental and numerical investigation of the reflection coefficient and the distributions of Wigner's reaction matrix for irregular graphs with absorption

    E-print Network

    Michal Lawniczak; Oleh Hul; Szymon Bauch; Petr Seba; Leszek Sirko

    2009-03-18

    We present the results of experimental and numerical study of the distribution of the reflection coefficient P(R) and the distributions of the imaginary P(v) and the real P(u) parts of the Wigner's reaction K matrix for irregular fully connected hexagon networks (graphs) in the presence of strong absorption. In the experiment we used microwave networks, which were built of coaxial cables and attenuators connected by joints. In the numerical calculations experimental networks were described by quantum fully connected hexagon graphs. The presence of absorption introduced by attenuators was modelled by optical potentials. The distribution of the reflection coefficient P(R) and the distributions of the reaction K matrix were obtained from the measurements and numerical calculations of the scattering matrix S of the networks and graphs, respectively. We show that the experimental and numerical results are in good agreement with the exact analytic ones obtained within the framework of random matrix theory (RMT).

  15. An algorithm for predicting tissue : Blood partition coefficients of organic chemicals from n?octanol: Water partition coefficient data

    Microsoft Academic Search

    Patrick Poulin; Kannan Krishnan

    1995-01-01

    The objectives of the present study were (1) to develop an algorithm to predict tissue : blood partition coefficients (PCs) of organic chemicals from n?octanol : water (Ko\\/w) PC data, and (2) to apply this algorithm to predict the rat tissue : blood PCs of some relatively hydrophilic organics, particularly ketones, alcohols, and acetate esters. The algorithm, developed by modifying

  16. Predicting energy absorption in a foam-filled thin-walled aluminum tube based on experimentally determined strengthening coefficient

    Microsoft Academic Search

    Halit Kavi; A. Kaan Toksoy; Mustafa Guden

    2006-01-01

    The energy absorption in a foam-filled thin-walled circular Al tube was investigated based on the experimentally determined strengthening coefficient of filling using Al and polystyrene closed-cell foams with three different densities. Foam filling was found to change the deformation mode of tube from diamond (empty tube) into concertina, regardless the foam type and density used. Although foam filling resulted in

  17. Finite element analysis and modeling of water absorption by date pits during a soaking process

    PubMed Central

    Waezi-Zadeh, Motahareh; Ghazanfari, Ahmad; Noorbakhsh, Shahin

    2010-01-01

    Date pits for feed preparation or oil extraction are soaked in water to soften before milling or extrusion. Knowledge of water absorption by the date pits helps in better managing the soaking duration. In this research, the process of water absorption by date pits was modeled and analyzed using Fick’s second law of diffusion, finite element approach, and Peleg model. The moisture content of the pits reached to its saturation level of 41.5% (wet basis) after 10 d. The estimated coefficient of diffusion was 9.89×10?12 m2/s. The finite element model with a proposed ellipsoid geometry for a single date pit and the analytical model fitted better to the experimental data with R 2 of 0.98. The former model slightly overestimated the moisture content of the pits during the initial stages of the soaking and the latter model generally underestimated this variable through the entire stages of soaking process. PMID:20593512

  18. Determination of total x-ray absorption coefficient using non-resonant x-ray emission

    Microsoft Academic Search

    A. J. Achkar; T. Z. Regier; E. J. Monkman; K. M. Shen; D. G. Hawthorn

    2011-01-01

    An alternative measure of x-ray absorption spectroscopy (XAS) called inverse partial fluorescence yield (IPFY) has recently been developed that, unlike conventional electron yield (EY) and fluorescence yield (FY) measurements, is both bulk sensitive and does not experience saturation or self-absorption effects. In this manuscript, we show that the angle dependence of IPFY can also provide a direct measure of the

  19. Inversion of the volume scattering function and spectral absorption in coastal waters with biogeochemical implications

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Huot, Y.; Gray, D. J.; Weidemann, A.; Rhea, W. J.

    2013-06-01

    In the aquatic environment, particles can be broadly separated into phytoplankton (PHY), non-algal particle (NAP) and dissolved (or very small particle, VSP) fractions. Typically, absorption spectra are inverted to quantify these fractions, but volume scattering functions (VSFs) can also be used. Both absorption spectra and VSFs were used to calculate particle fractions for an experiment in Chesapeake Bay. A complete set of water inherent optical properties was measured using a suite of commercial instruments and a prototype Multispectral Volume Scattering Meter (MVSM); the chlorophyll concentration, [Chl] was determined using the HPLC method. The total scattering coefficient (measured by an ac-s) and the VSF (at a few backward angles, measured by a HydroScat 6 and an ECO-VSF) agreed with the LISST and MVSM data within 5%, thus indicating inter-instrument consistency. The size distribution and scattering parameters for PHY, NAP and VSP were inverted from measured VSFs. For the absorption inversion, the "dissolved" absorption spectra were measured for filtrate passing through a 0.2 ?m filter, whereas [Chl] and NAP absorption spectra were inverted from the particulate fraction. Even though the total scattering coefficient showed no correlation with [Chl], estimates of [Chl] from the VSF-inversion agreed well with the HPLC measurements (r = 0.68, mean relative error s = -20%). The scattering associated with NAP and VSP both correlated well with the NAP and "dissolved" absorption coefficients, respectively. While NAP dominated forward, and hence total, scattering, our results also suggest that the scattering by VSP was far from negligible and dominated backscattering.

  20. Investigations of the attenuation coefficient of a narrow-bandwidth pulsed laser beam in water

    Microsoft Academic Search

    Jianhui Bai; Juan Liu; Yi Huang; Yinan Liu; Lu Sun; Dahe Liu; E. S. Fry

    2007-01-01

    The attenuation coefficient of a pulsed laser beam in water is investigated experimentally. It is found that the attenuation coefficient is dependent on the pulse energy and the linewidth of the laser, rather than a constant. The attenuation coefficient for a narrow linewidth laser can exceed that of a broad linewidth laser due to stimulated Brillouin scattering when the laser

  1. Determination of fixed water in rocks by infrared absorption

    USGS Publications Warehouse

    Breger, I.A.; Chandler, J.C.

    1969-01-01

    An infrared absorption technique has been developed for the quantitative determination of "fixed water" (H2O+) in rocks. Potassium bromide disks containing 2-mg samples are scanned in the 3-??m spectral region and absorption at 2.96 ??m is determined. Although the exact nature of this peak is not known, other than that it is caused by an interaction between the potassium bromide and hydroxyl groups and water, it can be used for quantitative analysis. Rock samples, other than those containing significant percentages of clay minerals, can be analyzed with a standard deviation of 0.26%.

  2. Study of Water Absorption in Raffia vinifera Fibres from Bandjoun, Cameroon

    PubMed Central

    Sikame Tagne, N. R.; Njeugna, E.; Fogue, M.; Drean, J.-Y.; Nzeukou, A.; Fokwa, D.

    2014-01-01

    The study is focused on the water diffusion phenomenon through the Raffia vinifera fibre from the stem. The knowledge on the behavior of those fibres in presence of liquid during the realization of biocomposite, is necessary. The parameters like percentage of water gain at the point of saturation, modelling of the kinetic of water absorption, and the effective diffusion coefficient were the main objectives. Along a stem of raffia, twelve zones of sampling were defined. From Fick's 2nd law of diffusion, a new model was proposed and evaluated compared to four other models at a constant temperature of 23°C. From the proposed model, the effective diffusion coefficient was deduced. The percentage of water gain was in the range of 303–662%. The proposed model fitted better to the experimental data. The estimated diffusion coefficient was evaluated during the initial phase and at the final phase. In any cross section located along the stem of Raffia vinifera, it was found that the effective diffusion coefficient increases from the periphery to the centre during the initial and final phases. PMID:24592199

  3. Retrieval of phytoplankton biomass from simultaneous inversion of reflectance, the diffuse attenuation coefficient, and Sun-induced fluorescence in coastal waters

    Microsoft Academic Search

    Yannick Huot; Catherine A. Brown; John J. Cullen

    2007-01-01

    A model has been developed to retrieve phytoplankton absorption, a proxy for phytoplankton biomass, from observations of reflectance (R) and the diffuse attenuation coefficient (K d) collected by moored radiometers in coastal waters, where high concentrations of chromophoric dissolved organic matter (CDOM) confound conventional ocean color algorithms. The inversion uses simultaneously two forward models: (1) a look-up table (LUT) that

  4. Retrieval of phytoplankton biomass from simultaneous inversion of reflectance, the diffuse attenuation coefficient, and Sun-induced fluorescence in coastal waters

    Microsoft Academic Search

    Yannick Huot; Catherine A. Brown; John J. Cullen

    2007-01-01

    A model has been developed to retrieve phytoplankton absorption, a proxy for phytoplankton biomass, from observations of reflectance (R) and the diffuse attenuation coefficient (Kd) collected by moored radiometers in coastal waters, where high concentrations of chromophoric dissolved organic matter (CDOM) confound conventional ocean color algorithms. The inversion uses simultaneously two forward models: (1) a look-up table (LUT) that accounts

  5. Variations of light absorption by suspended particles with chlorophyll a concentration in oceanic (case 1) waters: Analysis and implications for bio-optical models

    Microsoft Academic Search

    Annick Bricaud; André Morel; Marcel Babin; Karima Allali; Hervé Claustre

    1998-01-01

    Spectral absorption coefficients of total particulate matter ap(lambda) were determined using the in vitro filter technique. The present analysis deals with a set of 1166 spectra, determined in various oceanic (case 1) waters, with field chl a concentrations () spanning 3 orders of magnitude (0.02-25 mgm-3). As previously shown [Bricaud et al., 1995] for the absorption coefficients of living phytoplankton

  6. Backscattering and absorption coefficients for electrons: Solutions of invariant embedding transport equations using a method of convergence

    SciTech Connect

    Figueroa, C.; Brizuela, H.; Heluani, S. P. [Laboratorio de Física del Sólido, Dpto. de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina)

    2014-05-21

    The backscattering coefficient is a magnitude whose measurement is fundamental for the characterization of materials with techniques that make use of particle beams and particularly when performing microanalysis. In this work, we report the results of an analytic method to calculate the backscattering and absorption coefficients of electrons in similar conditions to those of electron probe microanalysis. Starting on a five level states ladder model in 3D, we deduced a set of integro-differential coupled equations of the coefficients with a method know as invariant embedding. By means of a procedure proposed by authors, called method of convergence, two types of approximate solutions for the set of equations, namely complete and simple solutions, can be obtained. Although the simple solutions were initially proposed as auxiliary forms to solve higher rank equations, they turned out to be also useful for the estimation of the aforementioned coefficients. In previous reports, we have presented results obtained with the complete solutions. In this paper, we present results obtained with the simple solutions of the coefficients, which exhibit a good degree of fit with the experimental data. Both the model and the calculation method presented here can be generalized to other techniques that make use of different sorts of particle beams.

  7. Wide absorption spectrum measuring methods by DFB-LDs in water vapor detection system

    NASA Astrophysics Data System (ADS)

    Liu, Y. N.; Chang, J.; Lian, J.; Wang, Q.; Lv, G. P.; Wang, W. J.; Liu, Z.; Liu, X. Z.; Zhang, S. S.; Wang, Z. L.; Jiang, S.; Zhu, C. G.; Wei, W.; Sun, B. N.

    2014-09-01

    Two measuring methods of the wide absorption spectrum by distributed feedback laser diodes (DFB-LDs) are presented in detecting the water vapor absorption line. One is the subsection scanning method, and it takes advantage of the wide spectrum tuning range by the temperature modulation and fast spectrum tuning speed by current modulation. Specifically, this method is realized by dividing a target spectral region into several sections which correspond to the specific temperature of DFB-LD, scanning every section by current modulation for hundreds times, and averaging the data to raise the signal to noise ratio (SNR), then combining all sections to get the whole spectrum. An accuracy of 10 ppmv had been obtained in the measurement of water vapor with a 10-cm path length by this method. Another is data fitting method, based on the absorption line-shape function; the absorption line can be described by fitting with partial measured data. The fitting absorption line was fitted well with the measured data, and the square of correlation coefficient (R-square) was no less than 0.99.

  8. Absorption coefficient and site-specific mass absorption efficiency of elemental carbon in aerosols over urban, rural, and high-altitude sites in India.

    PubMed

    Ram, Kirpa; Sarin, M M

    2009-11-01

    Temporal and spatial variability in the absorption coefficient (b(abs), Mm(-1)) and mass absorption efficiency (MAE, sigma(abs), m(2)g(-1)) of elemental carbon (EC) in atmospheric aerosols studied from urban, rural, and high-altitude sites is reported here. Ambient aerosols, collected on tissuquartz filters, are analyzed for EC mass concentration using thermo-optical EC-OC analyzer, wherein simultaneously measured optical-attenuation (ATN, equivalent to initial transmittance) of 678 nm laser source has been used for the determination of MAE and absorption coefficient. At high-altitude sites, measured ATN and surface EC loading (EC(s), microg cm(-2)) on the filters exhibit linear positive relationship (R(2) = 0.86-0.96), suggesting EC as a principal absorbing component. However, relatively large scatter in regression analyses for the data from urban sites suggests contribution from other species. The representative MAE of EC, during wintertime (Dec 2004), at a rural site (Jaduguda) is 6.1 +/- 2.0 m(2)g(-1). In contrast, MAE at the two high-altitude sites is 14.5 +/- 1.1 (Manora Peak) and 10.4 +/- 1.4 (Mt. Abu); and that at urban sites is 11.1 +/- 2.6 (Allahabad) and 11.3 +/- 2.2 m(2)g(-1) (Hisar). The long-term average MAE at Manora Peak (February 2005 to June 2007) is 12.8 +/- 2.9 m(2)g(-1) (range: 6.1-19.1 m(2)g(-1)). These results are unlike the constant conversion factor used for MAE in optical instruments for the determination of BC mass concentration. The absorption coefficient also shows large spatiotemporal variability; the lower values are typical of the high-altitude sites and higher values for the urban and rural atmosphere. Such large variability documented for the absorption parameters suggests the need for their suitable parametrization in the assessment of direct aerosol radiative forcing on a regional scale. PMID:19924949

  9. Water Vapor Absorption in Early M-type Stars

    E-print Network

    M. Matsuura; I. Yamamura; H. Murakami; M. M. Freund; M. Tanaka

    1999-06-16

    The spectrometers onboard the Infrared Telescope in Space (IRTS) reveal water vapor absorption in early M-type stars, as early as M2. Previous observations detected H_2O vapor absorption only in stars later than M6, with the exception of the recent detection of H_2O in beta Peg (M2.5 II-III). In our sample of 108 stars, 67 stars have spectral types earlier than M6. The spectral types are established by means of their near-infrared colors on a statistical basis. Among the 67 stars of spectral types earlier than M6, we find water vapor absorption in six stars. The observed absorption features are interpreted using a local thermodynamic equilibrium model. The features are reasonably fitted by model spectra with excitation temperatures of 1000-1500 K and water column densities of 5x10^19 to 1x10^20 cm^-2. These numbers imply that the H_2O molecules are present in a region of the atmosphere, located above the photosphere. Furthermore, our analysis shows a good correlation between the H_2O absorption band strength, and the mid-infrared excess due to the circumstellar dust. We discuss the relation between the outer atmosphere and the mass loss.

  10. A far wing line shape theory and its application to the water continuum absorption in the infrared region. I

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, R. H.

    1991-01-01

    The present theory for the continuous absorption that is due to the far-wing contribution of allowed lines is based on the quasistatic approximation for the far wing limit and the binary collision approximation of one absorber molecule and one bath molecule. The validity of the theory is discussed, and numerical results of the water-continuum absorption in the IR region are presented for comparison with experimental data. Good agreement is obtained for both the magnitude and temperature dependence of the absorption coefficients.

  11. Water vapor continuum: Whether collision-induced absorption is involved?

    NASA Astrophysics Data System (ADS)

    Vigasin, A. A.

    2014-11-01

    In a series of recent publications, the idea is pursued to shed a new light on the theory of the water vapor continuum absorption invoking the mechanism of collision-induced absorption. In the opinion of the present author, a portion of theoretical suggestions on this subject is biased and may thus lead to untenable conclusions about the nature of the continuum. The most typical drawback consists of improper consideration of statistics in the ensemble of interacting monomers that lead to embedding incorrect statistical weights to various types of molecular pairs which can form. The current note aims at clarifying the term “collision-induced absorption” in order to avoid incongruity in understanding the nature of the water vapor continuum.

  12. Effect of electron collisions on transport coefficients induced by the inverse bremsstrahlung absorption in plasmas

    NASA Astrophysics Data System (ADS)

    Bendib, A.; Tahraoui, A.; Bendib, K.; Mohammed El Hadj, K.; Hüller, S.

    2005-03-01

    The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path ?ei compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in the analysis, which allows us to consider with sufficient accuracy to describe plasmas with arbitrary atomic number Z. Practical numerical fits of the transport coefficients are proposed as functions of Z and the collisionality parameter ?ei/L.

  13. A Novel Absorption Cycle for Combined Water Heating, Dehumidification, and Evaporative Cooling

    SciTech Connect

    CHUGH, Devesh [University of Florida, Gainesville; Gluesenkamp, Kyle R [ORNL; Abdelaziz, Omar [ORNL; Moghaddam, Saeed [University of Florida, Gainesville

    2014-01-01

    In this study, development of a novel system for combined water heating, dehumidification, and space evaporative cooling is discussed. Ambient water vapor is used as a working fluid in an open system. First, water vapor is absorbed from an air stream into an absorbent solution. The latent heat of absorption is transferred into the process water that cools the absorber. The solution is then regenerated in the desorber, where it is heated by a heating fluid. The water vapor generated in the desorber is condensed and its heat of phase change is transferred to the process water in the condenser. The condensed water can then be used in an evaporative cooling process to cool the dehumidified air exiting the absorber, or it can be drained if primarily dehumidification is desired. Essentially, this open absorption cycle collects space heat and transfers it to process water. This technology is enabled by a membrane-based absorption/desorption process in which the absorbent is constrained by hydrophobic vapor-permeable membranes. Constraining the absorbent film has enabled fabrication of the absorber and desorber in a plate-and-frame configuration. An air stream can flow against the membrane at high speed without entraining the absorbent, which is a challenge in conventional dehumidifiers. Furthermore, the absorption and desorption rates of an absorbent constrained by a membrane are greatly enhanced. Isfahani and Moghaddam (Int. J. Heat Mass Transfer, 2013) demonstrated absorption rates of up to 0.008 kg/m2s in a membrane-based absorber and Isfahani et al. (Int. J. Multiphase Flow, 2013) have reported a desorption rate of 0.01 kg/m2s in a membrane-based desorber. The membrane-based architecture also enables economical small-scale systems, novel cycle configurations, and high efficiencies. The absorber, solution heat exchanger, and desorber are fabricated on a single metal sheet. In addition to the open arrangement and membrane-based architecture, another novel feature of the cycle is recovery of the solution heat energy exiting the desorber by process water (a process-solution heat exchanger ) rather than the absorber exiting solution (the conventional solution heat exchanger ). This approach has enabled heating the process water from an inlet temperature of 15 C to 57 C (conforming to the DOE water heater test standard) and interfacing the process water with absorbent on the opposite side of a single metal sheet encompassing the absorber, process-solution heat exchanger, and desorber. The system under development has a 3.2 kW water heating capacity and a target thermal coefficient of performance (COP) of 1.6.

  14. Line shapes \\/absorption coefficients\\/ for satellites and inversion of the data to obtain interaction potentials

    Microsoft Academic Search

    R. J. Exton; W. L. Snow

    1978-01-01

    Line shapes for cesium broadened by xenon and neopentane have been measured in an absorption cell. The growth of the red satellites, both primary and secondary, were studied on the first five principal series doublets and on the first S-D forbidden doublet. An inversion scheme based on a nearest-neighbor density was employed to invert the measured line shapes and obtain

  15. Rapid determination of partition coefficients between n-octanol/water for cardiovascular therapies.

    PubMed

    Ranade, Vasant; Somberg, John C

    2002-01-01

    The lipid solubility of a pharmaceutical may greatly influence its tissue activity. To evaluate lipid solubility of a group of cardiovascular agents a procedure to determine partition coefficients in n-octanol/water for a series of cardiovascular compounds was described. Ultraviolet absorbance measurements were used to assess partitioning between the two liquid phases of these compounds. In this study, sotalol was found to be the most hydrophilic (n-octanol/water ratio of 0.33) and fosinopril-sodium was the most lipophilic (ratio of 6.19). This is a versatile method permitting the evaluation of lipophilicity and, thus, parameters governing the events leading to pharmacologic actions such as gastrointestinal dissolution, absorption, and bioavailability. These observations can be related to a drug series, composed of several compounds having structural similarities or minor variations. The lipid solubility of a compound can markedly alter its side-effects profile, especially because lipophilic drugs enter the central nervous system with facility. Additionally, lipophilic agents may enter target tissue with greater ease than nonlipophilic compounds and thus possess local intracellular effects in addition to a macro systemic action. PMID:11782815

  16. Absorption characteristics of optically complex inland waters: Implications for water optical classification

    NASA Astrophysics Data System (ADS)

    Shi, Kun; Li, Yunmei; Li, Lin; Lu, Heng

    2013-06-01

    Multiple bio-optical measurements were conducted in inland waters of China, including Lake Taihu [spring and autumn], Lake Chaohu, Lake Dianchi, and Three Gorges Reservoirs. The variations in the absorption characteristics of chromophoric dissolved organic matter (CDOM), phytoplankton, and non-algal particles (NAP) and their relative contributions to total absorption among these waters were analyzed. The obtained results indicated that these areas are representative of the optically complex inland waters characterized by strong regional variations of their absorption properties. By means of the relative contributions of NAP and phytoplankton to the total water absorption at 550 and 675 nm, these waters were classified into three optical water types, each one having specific biogeochemical and optical properties. Two of the types were distinct and corresponded to waters that are optically controlled by NAP (Type I) and dominated by phytoplankton (Type III). Type II was related to relatively optically mixed waters where the absorption properties are controlled by NAP and phytoplankton. Additionally, the differences in remote-sensing reflectance (Rrs) spectra among the three classified water types were clarified to establish optical criteria for identifying these water types. On this basis, the classification criteria for MERIS images were developed, which allowed one to cluster every Rrs spectrum into one of the three water types by comparing the values from band 6, band 8, and band 9 of MERIS images. The proposed criteria were subsequently conducted to map the water types of Lake Taihu using MERIS images.

  17. Determination of Absorption Coefficients for Complexes of Humic Acid 1S102H with Copper Ions in the Spectral Range 210-350 nm

    NASA Astrophysics Data System (ADS)

    Lavrik, N. L.

    2014-11-01

    Absorption spectra were used to determine weight-specific absorption coefficients for free humic acid (HA) macromolecules and those forming a complex with the Cu2+ metal ion. This was done using an approach involving measurement of the optical density in the absorption spectrum of the complexes and using known binding constants for binding of HA macromolecules with the copper ion. The weight-specific absorption coefficients of the complexes {HA-Cu2+} at ? =250 nm for [HA] =5·10-3 g/L were ?c =155 and 200 L·g-1·cm-1 for [CuSO4·5H2O] =1.25·10-4 and 2.5·10-4 M. The values obtained are several times higher than the absorption coefficients for the free form of HA, ?0 =46 L·g-1·cm-1.

  18. Interpretation of nonelectrolyte partition coefficients between dimyristoyl lecithin and water

    Microsoft Academic Search

    Jared M. Diamond; Yehuda Katz

    1974-01-01

    Summary Nonelectrolyte partition coefficients (K's) and free energies of solution (?Fl's) in dimyristoyl lecithin liposomes and in bulk nonpolar solvents were compared. Individual substituent groups tend to have consistent effects onK, permitting the extraction of incremental free energies (d?F), enthalpies (d?H), and entropies (d?S) of partition and of solution. Values of the selectivity constants and of d?Fl for the -CH2-and

  19. Water Absorption by Atmospheric Organic Particles: Evidence, Causes and Simulations

    NASA Astrophysics Data System (ADS)

    Saxena, Pradeep

    The optical and chemical properties of atmospheric fine particles and their ability to act as cloud condensation nuclei depend strongly upon their affinity for water. Laboratory experiments have shown that water-soluble sulfates and nitrates, which are major inorganic components of atmospheric fine particles, absorb water in an amount proportional to water vapor pressure. Analogous information about the interactions between water and organics is lacking. Moreover, the molecular composition of atmospheric particulate organics remains poorly characterized; information on the molecular composition of the water-soluble fraction is particularly sparse. Here we first analyze concurrent observations of particle chemical composition and water content from a continental nonurban (Grand Canyon) and an urban (Los Angeles) location to determine whether the water content of atmospheric particles is influenced by the presence of organics. We find that the aggregate hygroscopic properties of inorganic particles are altered substantially when organics are also present. For the nonurban location, organics enhance water absorption by inorganics. For the urban location, on the other hand, the net effect of organics is to diminish water absorption of the inorganics. Second, we identify specific compounds that are likely to contribute to the water-soluble fraction by juxtaposing published observations regarding the extraction characteristics and the molecular composition of atmospheric particulate organics with compound-specific solubility and condensibility for a wide variety of organics. We find that water-soluble organics, which constitute a substantial fraction of the total organic mass, include C2 to C7 multifunctional compounds (e.g. diacids, polyols, amino acids). Third, towards developing a simulation capability, we (1) synthesize published laboratory data to evaluate the water absorption behavior of multifunctional oxygenated organic compounds; and (2) test the reliability of the UNIFAC method for estimating water activities of aqueous organic solutions. Laboratory data show that multifunctional oxygenated compounds can absorb water over the entire range of relative humidities. For a wide variety of compounds (e.g., glycols, dicarboxylic acids, keto acids) and a wide range of solute concentrations (0 to over 90% by wt), we find that in most cases, water activities can be estimated within approximately 15% error.

  20. ADDENDUM: Inverse bremsstrahlung absorption in large radiation fields during binary collisions-classical theory. II(b). Summed rate coefficients for Coulomb collisions

    Microsoft Academic Search

    G. J. Pert

    1976-01-01

    For pt.II(a) see ibid., vol.9, p.463 (1976). The summation of the expressions obtained previously for the value of the absorption coefficient is performed analytically, and their asymptotic expansion derived. These results are shown to be in agreement with similar expressions obtained by other methods. It is concluded that this form represents a generalization of the Kramers-Gaunt low-field absorption coefficient.

  1. Measuring the acoustic absorption coefficient in biological tissue specimens using ultrasonic phase conjugation

    NASA Astrophysics Data System (ADS)

    Smagin, N. V.; Krutyansky, L. M.; Zelenova, Z. V.; Brysev, A. P.

    2014-03-01

    Acoustic absorption has been measured in a series of biological tissue specimens—porcine muscle, renal and fat tissues—by the standard insert-substitution method, as well as by ultrasonic phase conjugation. Comparison of the experimental results and revealed differences confirm the promise of using phase conjugate waves to measure acoustic losses in biological objects. It is demonstrated that in inhomogeneous tissues, the phase conjugation method makes it possible to obtain a more reliable estimate of dissipative losses.

  2. Effect of electron collisions on transport coefficients induced by the inverse bremsstrahlung absorption in plasmas

    Microsoft Academic Search

    A. Bendib; A. Tahraoui; K. Bendib; K. Mohammed El Hadj; S. Hueller

    2005-01-01

    The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path lambdaei compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in

  3. An Exergy Analysis of LiBr-Water Absorption Refrigerators

    NASA Astrophysics Data System (ADS)

    Asano, Hitoshi; Fujii, Terushige; Wang, Xiao; Origane, Takafumi; Katayama, Masatoshi; Inoue, Umeo

    Absorption refrigerators are very efficient as a heat recovery unit in a co-generation system.In order to design an absorption refrigerator for an arbitrary heat source properly, it is important to consider not only quantity but also quality of heat flow. The evaluation of exergy loss in each component is also effective for the improvement of system. This paper deals with the exergy analysis on a LiBr-water absorption refrigerator consisted of a single-and a double-effect cycle driven by the exhaust gas of the micro gas turbine with the output power of about 30 kW. Moreover, exergy loss in absorption process was eva1uated. As a result, it was shown that 80% of the exergy loss in an absorber was caused in absorption process, and the exergy loss decreased with decreasing the change in solution concentration in absorber. In these calculated results,the maximum cooling load of 77.8 kW was obtained from the exhaust gas with the temperature of 2900°C by utilizing both a single-and a double-effect cycles in combination. The energy and exergy efficiency of the system was 88.0% and 25.6%, respectively.

  4. Measurements of the evaporation coefficient of water based on molecular gas dynamics

    NASA Astrophysics Data System (ADS)

    Nakamura, Shigeto; Yano, Takeru

    2014-12-01

    We propose a novel method for measuring the evaporation coefficient of water using a sound-resonaiice experiment based on the theory of molecular gas dynamics. The evaporation coefficient is one of the parameters contained in the kinetic boundary condition. The evaporation coefficient of water is determined according to the pressure amplitude of the resonant sound wave in a cylindrical space bounded by a sound source and a vapor-liquid interface. The use of the sound wave enables us to conduct the experiment in a weak nonequilibrium state. By comparing the pressure amplitude with the results from a linear acoustic theory, including the effect of the evaporation coefficient on the amplitude variation, we demonstrate that the evaporation coefficient of water is approximately 1.0 near 300 K.

  5. Dynamics of absorption properties along a latitudinal gradient: sources of absorption in Australian inland waters

    NASA Astrophysics Data System (ADS)

    Hestir, E. L.; Campbell, G.; Malthus, T. J.; Dekker, A.; Botha, E.

    2013-12-01

    Australian inland waters are optically complex and vary spatially and temporally. Inversion of optical remote sensing data for the retrieval of optically active water quality constituents (chlorophyll, colored dissolved organic matter and total suspended solids) is impeded by the scarcity of inherent optical property (IOP) data sets. In 2012 a major measurement program commenced to improve understanding of IOPs in Australia. Seven large lakes were sampled along a latitudinal gradient in Eastern Australia; in situ observations were made of the absorption properties of the water quality during two epochs (wet and dry season). This study documents the seasonal, inter & intra lake variability of the absorption budget of Australian lakes. These data reveal the sources of biogeochemical constituents determining the light climate of lakes. Optically active water quality constituents (total suspended solids, chlorophyll-a, and colored dissolved organic matter) varied significantly between wet and dry season and between lakes. The primary contribution to the absorption budget was from non-algal particulate matter (NAP; 10-60%), followed by colored dissolved organic matter (CDOM; 20-80%). Absorption from phytoplankton contributed only 0-30% of the total budget. This indicates that these lakes are primarily light limited, though the limitation comes from multiple sources. The contribution of NAP to the total absorption budget showed the greatest amount of variance between wet and dry seasons. Examination of the organic matter and estimated phytoplankton biomass contributions to TSS reveal that chlorophyll is not the primary source of organic matter in Australian lakes: allochthonous inputs are the primary trophic driver. Finally, there is strong regional and seasonal variation in the IOPs of the lakes, with the exception of the slope of CDOM. The slope of CDOM was not significantly different between seasons (p=0.94). Non-parametric stepwise multiple comparisons showed the slope of CDOM was significantly different for only one lake, a mid-latitude, shallow, highly turbid diversion dam. The remaining IOP variability casts doubt on the suitability of a single parameterization for inland water remote sensing algorithms, with the possible exception of CDOM. IOP datasets representing the optical complexity and variability of geophysical and trophic conditions are needed for successful remote sensing application.

  6. Simultaneous identification of diffusion and absorption coefficients in a quasilinear elliptic problem

    NASA Astrophysics Data System (ADS)

    Egger, Herbert; Pietschmann, Jan-Frederik; Schlottbom, Matthias

    2014-03-01

    In this work, we consider the identifiability of two coefficients a(u) and c(x) in a quasilinear elliptic partial differential equation from the observation of the Dirichlet-to-Neumann map. We use a linearization procedure due to Isakov (1993 Arch. Ration. Mech. Anal. 124 1-12) and special singular solutions to first determine a(0) and c(x) for x ? ?. Based on this partial result, we are then able to determine a(u) for u \\in {R} by an adjoint approach.

  7. Giant Two-Photon Absorption Coefficient and Frequency Up-Converted Luminescence in Monolayer MoS2

    E-print Network

    Li, Yuanxin; Zhang, Saifeng; Zhang, Xiaoyan; Feng, Yanyan; Wang, Kangpeng; Zhang, Long; Wang, Jun

    2015-01-01

    Strong two-photon absorption (TPA) in monolayer MoS2 is demonstrated in contrast to saturable absorption (SA) in multilayer MoS2 under the excitation of femtosecond laser pulses in the near infrared region. MoS2 in the forms of monolayer single crystal and multilayer triangular islands are grown on either quartz or SiO2/Si by employing the seeding method through chemistry vapor deposition. The nonlinear transmission measurements reveal that monolayer MoS2 possesses a giant nonsaturation TPA coefficient, larger than that of conventional semiconductors. As a result of TPA, two-photon pumped frequency up-converted luminescence is observed directly in the monolayer MoS2. For the multilayer MoS2, the SA response is demonstrated with the ratio of the excited-state absorption cross section to ground-state cross section of 0.18. In addition, the laser damage threshold of the monolayer MoS2 is 97 GW/cm2, larger than that of the multilayer MoS2 of 78 GW/cm2.

  8. Experimental Evaluation of the Drag Coefficient of Water Rockets by a Simple Free-Fall Test

    ERIC Educational Resources Information Center

    Barrio-Perotti, R.; Blanco-Marigorta, E. Arguelles-Diaz, K.; Fernandez-Oro, J.

    2009-01-01

    The flight trajectory of a water rocket can be reasonably calculated if the magnitude of the drag coefficient is known. The experimental determination of this coefficient with enough precision is usually quite difficult, but in this paper we propose a simple free-fall experiment for undergraduate students to reasonably estimate the drag…

  9. Investigation of the Emission and Absorption Spectra of Water Vapor

    NASA Astrophysics Data System (ADS)

    Moskalenko, N. I.; Il'in, Yu. A.; Sadykov, M. S.

    2015-01-01

    Emission and absorption spectra of water vapor are measured and analyzed for temperatures 350-2500 K in the spectral range 0.57-25 ?m. Based on the developed mathematical model of radiative transfer, the parameters of spectral transmission functions of N2O vapors are obtained at different temperatures. Practical application of the obtained radiative characteristics is considered for solving problems of radiative heat exchange in high-temperature media and designing optoelectronic systems intended for monitoring of aero carriers.

  10. OCTANOL/WATER PARTITION COEFFICIENTS FOR EVALUATION OF HAZARDOUS WASTE LAND DISPOSAL: SELECTED CHEMICALS

    EPA Science Inventory

    Octanol/water partition coefficients were extracted from the literature, calculated using a molecular fragment database (CLOGP), or measured in the laboratory for selected chemicals. Agreement between measured values and calculated values was good for chemicals for which both mem...

  11. 40 CFR 799.6756 - TSCA partition coefficient (n-octanol/water), generator column method.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...coefficient correlation. Environmental Science and Technology 14:1227-1229 (1980...selected organic chemicals. Environmental Science and Technology 11:475-478 (1977...octanol/water systems. Environmental Science and Technology 16:4-10...

  12. 40 CFR 799.6756 - TSCA partition coefficient (n-octanol/water), generator column method.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...coefficient correlation. Environmental Science and Technology 14:1227-1229 (1980...selected organic chemicals. Environmental Science and Technology 11:475-478 (1977...octanol/water systems. Environmental Science and Technology 16:4-10...

  13. 40 CFR 799.6756 - TSCA partition coefficient (n-octanol/water), generator column method.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...coefficient correlation. Environmental Science and Technology 14:1227-1229 (1980...selected organic chemicals. Environmental Science and Technology 11:475-478 (1977...octanol/water systems. Environmental Science and Technology 16:4-10...

  14. 40 CFR 799.6756 - TSCA partition coefficient (n-octanol/water), generator column method.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...coefficient correlation. Environmental Science and Technology 14:1227-1229 (1980...selected organic chemicals. Environmental Science and Technology 11:475-478 (1977...octanol/water systems. Environmental Science and Technology 16:4-10...

  15. 40 CFR 799.6756 - TSCA partition coefficient (n-octanol/water), generator column method.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...coefficient correlation. Environmental Science and Technology 14:1227-1229 (1980...selected organic chemicals. Environmental Science and Technology 11:475-478 (1977...octanol/water systems. Environmental Science and Technology 16:4-10...

  16. Estimating Phospholipid Membrane Water Partition Coefficients Using Comprehensive Two-Dimensional Gas Chromatography

    E-print Network

    Tcaciuc, Alexandra Patricia

    Recent studies have shown that membrane–water partition coefficients of organic chemicals can be used to predict bioaccumulation and type I narcosis toxicity more accurately than the traditional K[subscript OW]-based ...

  17. Airborne differential absorption lidar system for water vapor investigations

    NASA Technical Reports Server (NTRS)

    Browell, E. V.; Carter, A. F.; Wilkerson, T. D.

    1981-01-01

    Range-resolved water vapor measurements using the differential-absorption lidar (DIAL) technique is described in detail. The system uses two independently tunable optically pumped lasers operating in the near infrared with laser pulses of less than 100 microseconds separation, to minimize concentration errors caused by atmospheric scattering. Water vapor concentration profiles are calculated for each measurement by a minicomputer, in real time. The work is needed in the study of atmospheric motion and thermodynamics as well as in forestry and agriculture problems.

  18. Indirect determination of octanol-water partition coefficients by microemulsion electrokinetic chromatography

    Microsoft Academic Search

    S. J. Gluck; M. H. Benkö; R. K. Hallberg; K. P. Steele

    1996-01-01

    Microemulsion electrokinetic chromatography (MEEKC) was assessed and developed as a screening tool for the indirect determination of octanol-water partition coefficients. The capacity factors from MEEKC were correlated to the octanol-water partition coefficients. The same microemulsion (50 mM SDS, 400 mM butanol and 32 mM heptane) was used at pH 1.19 and pH 12 allowing most compounds to be run in

  19. WATER USE AND EVAPOTRANSPIRATION COEFFICIENTS FOR CAMELINA SATIVA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The water use characteristics of Camelina sativa, an oilseed crop, were evaluated in an irrigation experiment in Maricopa, Arizona. Camelina (cv. Robinson) was grown between November 2006 and April 2007 in plots, each 10 by 17 m. Thirty-two of the field plots were replicated in a randomized block de...

  20. Variability in the light absorption coefficients of phytoplankton, non-algal particles, and colored dissolved organic matter in a subtropical bay (Brazil)

    NASA Astrophysics Data System (ADS)

    Ferreira, Amabile; Ciotti, Áurea Maria; Coló Giannini, Maria Fernanda

    2014-02-01

    This study characterized the variability in magnitudes and spectral shapes of the absorption coefficients of phytoplankton, detritus, and colored dissolved organic matter (CDOM) in a dynamic bay (Santos Bay) in southeastern Brazil in response to the contributions of the main estuarine channel and large tide variations, therefore in different time scales. Two strategies were adopted: (1) monthly year-round sampling in the estuarine channel and Santos Bay and (2) sampling in Santos Bay during spring/neap tides and cold/warm months. Chlorophyll-a concentration and CDOM absorption were higher during warm (wet) months, while the relative contribution of organic and inorganic particles was driven by neap/spring tide cycles. Salinity partially accounted for changes in optical variables, especially for CDOM absorption and total suspended matter (TSM) during cold months and neap tides, respectively. The spectral shapes of detritus and CDOM absorption showed relatively little variability for the entire dataset and were not considered feasible for monitoring purposes. The spectral shape of phytoplankton absorption (index of cell size) varied broadly, with no remarkable dependence on the sampling conditions. Comparison of absorption coefficients measured by the Quantitative Filter Technique (QFT) and Transmittance Reflectance (TR) method showed higher phytoplankton coefficients toward longer visible wavelengths (flatter spectra) and shallower slopes of detritus absorption yielded by the TR method. Our results also suggest that measurements at the near red spectral region result from not only scattering signals but also non-algal particle absorption.

  1. Biogeo-optics: particle optical properties and the partitioning of the spectral scattering coefficient of ocean waters.

    PubMed

    Stavn, Robert H; Richter, Scott J

    2008-05-10

    We propose a direct method of partitioning the particulate spectral scattering coefficient of the marine hydrosol based on the concurrent determination of the concentrations of particulate mineral and organic matter (the total mass of optically active scattering material exclusive of water) with the particulate spectral scattering coefficient. For this we derive a Model II multiple linear regression model. The multiple linear regression of the particulate spectral scattering coefficient against the independent variables, the concentrations of particulate inorganic matter and particulate organic matter, yields their mass-specific spectral scattering cross sections. The mass-specific spectral scattering cross section is simply the particle scattering cross section normalized to the particle mass, a fundamental optical efficiency parameter for the attenuation of electromagnetic radiation [Absorption and Scattering of Light by Small Particles, (Wiley-Interscience, 1983), pp. 80-81, 289]. It is possible to infer the optical properties of the suspended matter from the mass-specific spectral scattering cross sections. From these cross sections we partition the particulate spectral scattering coefficient into its major components. PMID:18470263

  2. Absorption Coefficients of the Methane-Nitrogen Binary Ice System: Implications for Pluto

    E-print Network

    Protopapa, S; Tegler, S C; Bergonio, J M

    2015-01-01

    The methane-nitrogen phase diagram of Prokhvatilov and Yantsevich (1983) indicates that at temperatures relevant to the surfaces of icy dwarf planets like Pluto, two phases contribute to the methane absorptions: nitrogen saturated with methane $\\bf{\\bar{N_{2}}}$:CH$_{4}$ and methane saturated with nitrogen $\\bf{\\bar{CH_{4}}}$:N$_{2}$. No optical constants are available so far for the latter component limiting construction of a proper model, in compliance with thermodynamic equilibrium considerations. New optical constants for solid solutions of methane diluted in nitrogen (N$_{2}$:CH$_{4}$) and nitrogen diluted in methane (CH$_{4}$:N$_{2}$) are presented at temperatures between 40 and 90 K, in the wavelength range 1.1-2.7 $\\mu$m at different mixing ratios. These optical constants are derived from transmission measurements of crystals grown from the liquid phase in closed cells. A systematic study of the changes of methane and nitrogen solid mixtures spectral behavior with mixing ratio and temperature is prese...

  3. Impact of measurement uncertainties on determination of chlorophyll-specific absorption coefficient for marine phytoplankton

    NASA Astrophysics Data System (ADS)

    McKee, David; Röttgers, Rüdiger; Neukermans, Griet; Calzado, Violeta Sanjuan; Trees, Charles; Ampolo-Rella, Marina; Neil, Claire; Cunningham, Alex

    2014-12-01

    Understanding variability in the chlorophyll-specific absorption of marine phytoplankton, aph*Chl (?), is essential for primary production modelling, calculation of underwater light field characteristics, and development of algorithms for remote sensing of chlorophyll concentrations. Previous field and laboratory studies have demonstrated significant apparent variability in aph*Chl (?) for natural samples and algal cultures. However, the potential impact of measurement uncertainties on derived values of aph*Chl (?) has received insufficient study. This study presents an analysis of measurement uncertainties for a data set collected in the Ligurian Sea in Spring and assesses the impact on estimates of aph*Chl (?). It is found that a large proportion of apparent variability in this set of aph*Chl (?) can be attributed to measurement errors. Application of the same analysis to the global NOMAD data set suggests that a significant fraction of variability in aph*Chl (?) may also be due to measurement errors. The copyright line for this article was changed on 16 JAN 2015 after original online publication.

  4. Mean absorption coefficient of H2O-air-MgCl2/CaCl2/NaCl thermal plasmas

    NASA Astrophysics Data System (ADS)

    Hannachi, R.; Cressault, Y.; Salem, D.; Teulet, Ph; Béji, L.; Ben Lakhdar, Z.

    2012-12-01

    Under the local thermodynamic equilibrium hypothesis, the mean absorption coefficients (MACs) were calculated for H2O-air-MgCl2/CaCl2/NaCl thermal plasmas in a temperature range from 300 to 30?000 K and at atmospheric pressure. The MACs were computed under the hypothesis of isothermal plasmas which allows a good description of the radiation absorbed in cold regions. In this study, we took into account the absorption radiation resulting from the atomic continuum, molecular continuum, atomic lines and some molecular bands. Free-free transitions (bremsstrahlung) and free-bound (electron-ion recombination and electron attachment) or bound-free transitions in terms of absorption were considered for the calculation of atomic continuum. For bound-bound transitions, natural, resonance, van der Waals, Stark and Doppler effects were taken into account for the line broadenings while the escape factors were used to treat the self-absorption of the resonance lines. Molecular continuum was considered for the main molecules (H2, O2, N2, OH, NO, H2O, N2O, NO2, O3, NO3 and N2O5) whereas we studied only diatomic systems O2, N2, NO and N_2^+ for the absorption of molecular bands. The influence of the proportion of MgCl2, CaCl2 or NaCl in a water-air mixture was analysed as the effect of the strong self-absorbed resonance lines of the alkaline salts (Ca, Ca+, Na, Na+, Mg, Mg+, Cl and Cl+). Our results show that a low concentration of alkaline salts (less than 1% in molar proportions) in the plasma increased the MACs at low temperatures (T < 10?000 K) due to the resonance lines mainly localized in the near-UV and visible spectral regions in opposition to hydrogen, oxygen or nitrogen species for which 90% of them exist in ultraviolet. In addition to the atomic and molecular continuum, the absorption radiation of molecular bands is important at low temperatures.

  5. Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV to 20 MeV for elements Z=1 to 92 and 48 additional substances of dosimetric interest

    Microsoft Academic Search

    J. H. Hubbell; Stephen M Seltzer

    1995-01-01

    Tables and graphs of the photon mass attenuation coefficient mu\\/rho and the mass energy-absorption coefficient mu(en)\\/rho are presented for all of the elements Z=1 to 92, and for 48 compounds and mixtures of radiological interest. The tables cover energies of the photon (x ray, gamma ray, bremsstrahlung) from 1 keV to 20 MeV. The mu\\/rho values are taken from the

  6. The development of an integrating cavity absorption meter to measure optical absorption of pure waters and suspended particulates

    E-print Network

    Pope, Robin Merl

    1990-01-01

    -0. 34 4. 46 -0. 90 In initial cavity designs, the observed increase in absorption at high concentrations of scatterers was attributed to creation of an anisotropy of the Fo irradiance at the sample surface by the So detector Aber. Specifically... . . 20 13 (SI/SO) vs volume for fixed sainple absorption . 23 14 Observed absorption of water at 630 nm versus concentration of nonabsorbing scatterers in models II and V. . . . . . . . . . . 25 15 I&adiance vs distance from sample boundary . . 28...

  7. Hydrodynamic coefficients of a two-dimensional, truncated rectangular floating structure in shallow water

    Microsoft Academic Search

    Y. Drobyshevski

    2004-01-01

    The paper seeks to examine hydrodynamic coefficients of a rectangular structure in shallow water and to establish analytical formulae for fast computations. A two-dimensional rectangular profile is considered with the under-bottom clearance assumed to be small compared with structure dimensions and the water depth. Following the method of matched asymptotic expansions, the radiation problem is solved under assumptions of the

  8. Tricaprylin-water partition coefficients and their temperature dependence for selected chlorobenzenes

    Microsoft Academic Search

    Nisheeth P. Bahadur; Wan-Ying Shiu; David G. B. Boocock; Donald Mackay

    1999-01-01

    Measurements of partition coefficients between tricaprylin (glyceryl tri-n-octanoate) and water are reported for seven chlorobenzenes (1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene) between 5 and 45 C. The values are compared with reported data on octanol-water and triolein-water partition coefficients. The van`t Hoff plots of log K{sub OW} versus T⁻¹ exhibit linearity with values of K{sub OW} increasing by

  9. Temperature dependence of CO2 and CO2-He mixture absorption coefficients in the Q-branch of (20o0)III <--0110 band

    NASA Astrophysics Data System (ADS)

    Aref'ev, Vladimir N.; Baranov, Yu. I.; Baranova, E. L.

    1997-03-01

    Absorption coefficients of pure carbon dioxide and CO2- He mixture have been measured in the Q-branch of the (20 degree(s)0)III IMP 0110 vibration-rotation band (1880.994 cm-1) at different pressures from 0.2 to 2.7 atm and temperatures: 294, 314, 333, and 353 K. The experiments were carried out by means of a 1-m multi-pass White cell with an optical path up to 90 m. The tunable CO- laser operated at P20, 8 IMP 7 (1880.9012 cm-1) transition was used as a radiation source. The absorption coefficients measured significantly exceeded the results of calculations with the Lorentzian shape due to important effects of line mixing. The temperature dependence of the difference between measured and calculated absorption coefficients are presented.

  10. Partition coefficients for environmentally important, multifunctional organic compounds in hexane + water

    SciTech Connect

    Schulte, J.; Ritter, S.; Hauthal, W.H.; Quitzsch, K. [Univ. Leipzig (Germany). Inst. fuer Physikalische und Theoretische Chemie] [Univ. Leipzig (Germany). Inst. fuer Physikalische und Theoretische Chemie; Duerr, J.; Maurer, G. [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik] [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik

    1998-01-01

    Experimental results for the partition coefficient of 41 substances (several phenol, indole, biphenyl, and naphthalene derivates, polycyclic aromatic compounds, and polyfunctional haloaromatics) in hexane + water at 298.15 K are reported. Partition coefficients were measured by reversed phase high-performance liquid chromatography and the shake-flask method. The experimental results are compared successfully to predictions by the linear solvation energy relationship method.

  11. Condensation Coefficient Measurement for Water in the UMR Cloud Simulation Chamber

    Microsoft Academic Search

    D. E. Hagen; J. Schmitt; M. Trueblood; J. Carstens; D. R. White; D. J. Alofs

    1989-01-01

    A systematic series of condensation coefficient measurements of water have been made using the University of Missouri-Rolla cooled-wall expansion chamber which simulates the thermodynamics of cloud. This coefficient is seen to decrease from a value near unity, at the outset of simulation, to a value in the neighborhood of 0.01 toward the end of a simulation. Final values of this

  12. Water vapour and greenhouse trapping: The role of far infrared absorption

    Microsoft Academic Search

    Ashok Sinha; John E. Harries

    1995-01-01

    Few observations have been made of atmospheric absorption across the far infrared. Yet water vapour absorption in this spectral region may significantly effect climate. The impact of far infrared absorption is assessed by calculating the spectral variation of the total and water vapour greenhouse effects, for the sub-arctic winter (SAW) and tropical (TRP) standard atmospheres. Although the calculated efficiency of

  13. Cryogenic measurement of the optical absorption coefficient in sapphire crystals at 1.064(micro)m for the Large-scale Cryogenic Gravitational wave Telescope

    E-print Network

    Takayuki Tomaru; Takashi Uchiyama; Daisuke Tatsumi; Shinji Miyoki; Masatake Ohashi; Kazuaki Kuroda; Toshikazu Suzuki; Akira Yamamoto; Takakazu Shintomi

    2001-03-08

    We have applied laser calorimetry to the measurement of optical absorption in mono-crystalline sapphire at cryogenic temperatures. Sapphire is a promising candidate for the mirror substrates of the Large-scale Cryogenic Gravitational wave Telescope. The optical absorption coefficients of different sapphire samples at a wavelength of 1.064(micro)m at 5K were found to average 90ppm/cm.

  14. Optimum hot water temperature for absorption solar cooling

    SciTech Connect

    Lecuona, A.; Ventas, R.; Venegas, M.; Salgado, R. [Dpto. Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain); Zacarias, A. [ESIME UPA, IPN, Av. de las Granjas 682, Col. Santa Catarina, 02550, D.F. Mexico (Mexico)

    2009-10-15

    The hot water temperature that maximizes the overall instantaneous efficiency of a solar cooling facility is determined. A modified characteristic equation model is used and applied to single-effect lithium bromide-water absorption chillers. This model is based on the characteristic temperature difference and serves to empirically calculate the performance of real chillers. This paper provides an explicit equation for the optimum temperature of vapor generation, in terms of only the external temperatures of the chiller. The additional data required are the four performance parameters of the chiller and essentially a modified stagnation temperature from the detailed model of the thermal collector operation. This paper presents and discusses the results for small capacity machines for air conditioning of homes and small buildings. The discussion highlights the influence of the relevant parameters. (author)

  15. Experimental investigation of holes interaction effect on the sound absorption coefficient of micro-perforated panels under high and medium sound levels

    Microsoft Academic Search

    Rostand Tayong; Thomas Dupont; Philippe Leclaire

    2011-01-01

    This paper experimentally investigates the holes interaction effect on the sound absorption coefficient of micro-perforated panels under high and medium sound levels. The theoretical formulations are based on a semi-empirical approach and the use of Fok’s function to model the acoustic surface impedance. For the high sound level regime, an empirical power law involving three coefficients is adapted. It is

  16. Determination of oil/water and octanol/water distribution coefficients from aqueous solutions from four fossil fuels. [MS thesis; in oil-water and octanol-water

    SciTech Connect

    Thomas, B.L.

    1984-07-01

    Liquid fossil fuels, both petroleum and synthetically derived oils, are exceedingly complex mixtures of thousands of components. The effect of many of these energy-related components on the environment is largely unknown. Octanol/water distribution coefficients relate both to toxicity and to the bioaccumulation potential of chemical components. Use of these partition data in conjunction with component concentrations in the oils in environmental models provides important information on the fate of fossil fuel components when released to the environment. Octanol/water distribution data are not available for many energy-related organic compounds, and those data that are available have been determined for individual components in simple, one-component octanol/water equilibrium mixtures. In this study, methods for determining many octanol/water distribution coefficients from aqueous extracts of oil products were developed. Sample aqueous mixtures were made by equilibrating liquid fossil fuels with distilled water. This approach has the advantage of detecting interactions between components of interest and other sample components. Compound types studied included phenols, nitrogen bases, hydrocarbons, sulfur heterocyclic compounds, and carboxylic acids. Octanol/water distribution coefficients that were determined in this study ranged from 9.12 for aniline to 67,600 for 1,2-dimethylnaphthalene. Within a compound type, distribution coefficients increased logarithmically with increasing alkyl substitution and molecular weight. Additionally, oil/water distribution data were determined for oil components. These data are useful in predicting maximum environmental concentrations in water columns. 96 references, 26 figures, and 40 tables.

  17. Temporal Downscaling of Crop Coefficient and Crop Water Requirement from Growing Stage to Substage Scales

    PubMed Central

    Shang, Songhao

    2012-01-01

    Crop water requirement is essential for agricultural water management, which is usually available for crop growing stages. However, crop water requirement values of monthly or weekly scales are more useful for water management. A method was proposed to downscale crop coefficient and water requirement from growing stage to substage scales, which is based on the interpolation of accumulated crop and reference evapotranspiration calculated from their values in growing stages. The proposed method was compared with two straightforward methods, that is, direct interpolation of crop evapotranspiration and crop coefficient by assuming that stage average values occurred in the middle of the stage. These methods were tested with a simulated daily crop evapotranspiration series. Results indicate that the proposed method is more reliable, showing that the downscaled crop evapotranspiration series is very close to the simulated ones. PMID:22619572

  18. Measurement of the Soret coefficients in organic/water mixtures by thermal lens spectrometry

    NASA Astrophysics Data System (ADS)

    Cabrera, Humberto; Cordido, Flaminio; Velásquez, Ana; Moreno, Pablo; Sira, Eloy; López-Rivera, Santos A.

    2013-04-01

    In this work we utilize an alternative optical method based on thermal lens spectroscopy for characterizing the thermal diffusion in binary liquid mixtures. In this method, the thermal lens and the Soret signals are separated by a time interval to determine the Soret coefficients. As a demonstrative experiment, the Soret coefficients of isopropanol/water and acetone/water mixtures have been measured using that variant. Our results were compared with the recently published experimental and theoretical calculations and very good agreement was achieved.

  19. Chlorophyll-specific absorption of phytoplankton in waters of Zhujiang River mouth, China

    NASA Astrophysics Data System (ADS)

    Yang, Dingtian; Cao, Wenxi; Mao, Zhihua; Pan, Delu

    2006-12-01

    Light absorption, chlorophyll-specific absorption and package effect of phytoplankton in Zhujiang River mouth was studied on the two cruises of "Shiyan 2". The vertical distribution of phytoplankton in waters can be simulated by Gaussian equation; light absorption of phytoplankton was made on 25 mm GF/F filter, maximum light absorption of phytoplankton was at the depth 5-10m underwater. The value of chlorophyll-specific absorption was negatively correlated with chlorophyll a concentration. Package effect index also had a negative relationship with chlorophyll concentration. These results indicated that the characteristics of light absorption by phytoplankton varied in different waters were properly related to the phytoplankton concentration.

  20. MODIS-based retrieval of suspended sediment concentration and diffuse attenuation coefficient in Chinese estuarine and coastal waters

    NASA Astrophysics Data System (ADS)

    Sokoletsky, Leonid; Yang, Xianping; Shen, Fang

    2014-11-01

    Radiative transfer modelling in atmosphere, water, and on the air-water surface was used to create an algorithm and computer code for satellite monitoring Chinese estuarine and coastal waters. The atmospheric part of the algorithm is based on the Reference Evaluation of Solar Transmittance (REST) model for calculation of optical properties of the atmosphere from the top of the atmosphere to the target; for modelling optical properties from target towards satellite's sensor, an optical reciprocity principle has been used. An algorithm uses estimates derived from three different sources: 1) the MODIS-based software; 2) radiative transfer equations, and 3) well-known empirical relationships between measured parameters and optical depths and transmittances for such atmospheric components as molecules, aerosols, ozone, nitrogen dioxide, precipitable water vapor and uniformly mixed gases. Using this model allowed us to derive a reliable relationship relating an important parameter, the diffuse-to-global solar incoming irradiance ratio, to the aerosol optical thickness, solar zenith angle and wavelength. The surface and underwater parts of the algorithm contained theoretical and semi-empirical relationships between inherent (such as absorption, scattering and backscattering coefficients) and apparent (remote-sensing reflectance and diffuse attenuation coefficient, Kd) optical properties, and suspended sediment concentration (SSC) measured in the Yangtze River Estuary and its adjacent coastal area. The first false colour maps of SSC and Kd demonstrated a well accordance with the multi-year field observations in the region, and suggest promise for use of this algorithm for the regular monitoring of Chinese and worldwide natural waters.

  1. Gas-film coefficients for the volatilization of ketones from water

    USGS Publications Warehouse

    Rathbun, R.E.; Tai, D.Y.

    1986-01-01

    Volatilization is a significant process in determining the fate of many organic compounds in streams and rivers. Quantifying this process requires knowledge of the mass-transfer coefficient from water, which is a function of the gas-film and liquid-film coefficients. The gas-film coefficient can be determined by measuring the flux for the volatilization of pure organic liquids. Volatilization fluxes for acetone, 2-butanone, 2-pentanone, 3-pentanone, 4-methyl-2-pentanone, 2-heptanone, and 2-octanone were measured in the laboratory over a range of temperatures. Gas-film coefficients were then calculated from these fluxes and from vapor pressure data from the literature. An equation was developed for predicting the volatilization flux of pure liquid ketones as a function of vapor pressure and molecular weight. Large deviations were found for acetone, and these were attributed to the possibility that acetone may be hydrogen bonded. A second equation for predicting the flux as a function of molecular weight and temperature resulted in large deviations for 4methyl-2-pentanone. These deviations were attributed to the branched structure of this ketone. Four factors based on the theory of volatilization and relating the volatilization flux or rate to the vapor pressure, molecular weight, temperature, and molecular diffusion coefficient were not constant as suggested by the literature. The factors generally increased with molecular weight and with temperature. Values for acetone corresponded to ketones with a larger molecular weight, and the acetone factors showed the greatest dependence on temperature. Both of these results are characteristic of compounds that are hydrogen bonded. Relations from the literature commonly used for describing the dependence of the gas-film coefficient on molecular weight and molecular diffusion coefficient were not applicable to the ketone gas-film coefficients. The dependence on molecular weight and molecular diffusion coefficient was in general U-shaped with the largest coefficients observed for acetone, the next largest for 2octanone, and the smallest for 2-pentanone and 3-pentanone. The gas-film coefficient for acetone was much more dependent on temperature than were the coefficients for the other ketones. Such behavior is characteristic of hydrogen-bonded substances. Temperature dependencies of the other ketones were about twice the theoretical value, but were comparable to a literature value for water. Ratios of the ketone gas-film coefficients to the gasfilm coefficients for the evaporation of water were approximately constant for all the ketones except for acetone, whose values were considerably larger. The ratios increased with temperature; however, the increases were small except for acetone. These ratios can be combined with an equation from the literaure for predicting the gasfilm coefficient for evaporation of water from a canal to predict the gas-film coefficients for the volatilization of ketones from streams and rivers.

  2. A method to determine the acoustic reflection and absorption coefficients of porous media by using modal dispersion in a waveguide.

    PubMed

    Prisutova, Jevgenija; Horoshenkov, Kirill; Groby, Jean-Philippe; Brouard, Bruno

    2014-12-01

    The measurement of acoustic material characteristics using a standard impedance tube method is generally limited to the plane wave regime below the tube cut-on frequency. This implies that the size of the tube and, consequently, the size of the material specimen must remain smaller than a half of the wavelength. This paper presents a method that enables the extension of the frequency range beyond the plane wave regime by at least a factor of 3, so that the size of the material specimen can be much larger than the wavelength. The proposed method is based on measuring of the sound pressure at different axial locations and applying the spatial Fourier transform. A normal mode decomposition approach is used together with an optimization algorithm to minimize the discrepancy between the measured and predicted sound pressure spectra. This allows the frequency and angle dependent reflection and absorption coefficients of the material specimen to be calculated in an extended frequency range. The method has been tested successfully on samples of melamine foam and wood fiber. The measured data are in close agreement with the predictions by the equivalent fluid model for the acoustical properties of porous media. PMID:25480044

  3. On the optical absorption coefficient of Gd hydride thin films: coexistence of the Gd (GdH2) and GdHx (GdH2+y) phases

    Microsoft Academic Search

    W E Vargas; D E Azofeifa; N Clark

    2009-01-01

    Electron beam evaporated Pd-capped Gd thin films were deposited on quartz substrates and subsequently hydrided. Transmittance spectra of these bilayer systems, under unpolarized normal illumination, were obtained and used in an inversion approach from which the spectral dependence of the effective optical constants is obtained. The optical absorption coefficient of the ?-phase GdHx (with 1 < x ? 2) is

  4. Biogeochemical origins of particles obtained from the inversion of the volume scattering function and spectral absorption in coastal waters

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Huot, Y.; Gray, D. J.; Weidemann, A.; Rhea, W. J.

    2013-09-01

    In the aquatic environment, particles can be broadly separated into phytoplankton (PHY), non-algal particle (NAP) and dissolved (or very small particle, VSP) fractions. Typically, absorption spectra are inverted to quantify these fractions, but volume scattering functions (VSFs) can also be used. Both absorption spectra and VSFs were used to estimate particle fractions for an experiment in the Chesapeake Bay. A complete set of water inherent optical properties was measured using a suite of commercial instruments and a prototype Multispectral Volume Scattering Meter (MVSM); the chlorophyll concentration, [Chl] was determined using the HPLC method. The total scattering coefficient measured by an ac-s and the VSF at a few backward angles measured by a HydroScat-6 and an ECO-VSF agreed with the LISST and MVSM data within 5%, thus indicating inter-instrument consistency. The size distribution and scattering parameters for PHY, NAP and VSP were inverted from measured VSFs. For the absorption inversion, the "dissolved" absorption spectra were measured for filtrate passing through a 0.2 ?m filter, whereas [Chl] and NAP absorption spectra were inverted from the particulate fraction. Even though the total scattering coefficient showed no correlation with [Chl], estimates of [Chl] from the VSF-inversion agreed well with the HPLC measurements (r = 0.68, mean relative errors = -20%). The scattering associated with NAP and VSP both correlated well with the NAP and "dissolved" absorption coefficients, respectively. While NAP dominated forward, and hence total, scattering, our results also suggest that the scattering by VSP was far from negligible and dominated backscattering. Since the sizes of VSP range from 0.02 to 0.2 ?m, covering (a portion of) the operationally defined "dissolved" matter, the typical assumption that colored dissolved organic matter (i.e., CDOM) does not scatter may not hold, particularly in a coastal or estuarine environment.

  5. Sediment pore water distribution coefficients of PCB congeners in enriched black carbon sediment

    PubMed Central

    MARTINEZ, ANDRES; O'SULLIVAN, COLIN; REIBLE, DANNY; HORNBUCKLE, KERI C.

    2013-01-01

    More than 2300 sediment pore water distribution coefficients (KPCBi ds) of 93 polychlorinated biphenyls (PCBs) were measured and modeled from sediments from Indiana Harbor and Ship Canal. KPCBi ds were calculated from previously reported bulk sediment values and newly analyzed pore water. PCBs in pore waters were measured using SPME PDMS-fiber and ?PCB ranged from 41 to 1500 ng L?1. The resulting KPCBi ds were ~ 1 log unit lower in comparison to other reported values. A simple model for the KPCBi d consisted of the product of the organic carbon fraction and the octanol-water partition coefficient and provided an excellent prediction for the measured values, with a mean square error of 0.09 ± 0.06. Although black carbon content is very high in these sediments and was expected to play an important role in the distribution of PCBs, no improvement was obtained when a two-carbon model was used. PMID:23974165

  6. Slip flow coefficient analysis in water hydraulics gear pump for environmental friendly application

    NASA Astrophysics Data System (ADS)

    Yusof, A. A.; Wasbari, F.; Zakaria, M. S.; Ibrahim, M. Q.

    2013-12-01

    Water hydraulics is the sustainable option in developing fluid power systems with environmental friendly approach. Therefore, an investigation on water-based external gear pump application is being conducted, as a low cost solution in the shifting effort of using water, instead of traditional oil hydraulics in fluid power application. As the gear pump is affected by fluid viscosity, an evaluation has been conducted on the slip flow coefficient, in order to understand to what extent the spur gear pump can be used with water-based hydraulic fluid. In this paper, the results of a simulated study of variable-speed fixed displacement gear pump are presented. The slip flow coefficient varies from rotational speed of 250 RPM to 3500 RPM, and provides volumetric efficiency ranges from 9 % to 97% accordingly.

  7. Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water

    NASA Astrophysics Data System (ADS)

    Davies, James F.; Miles, Rachael E. H.; Haddrell, Allen E.; Reid, Jonathan P.

    2014-09-01

    We report measurements of the vapor pressure of water over the supercooled temperature range 248 to 273 K derived from evaporation kinetics measurements of single water droplets. Accurate measurements of the relative humidity of the surrounding gas phase are derived from comparative and sequential measurements of the evaporation kinetics of droplets containing sodium chloride. The temperature dependence of the vapor pressure of supercooled water is shown to conform closely to the parameterization provided by Murphy and Koop (2005) once the uncertainties in experimental and thermophysical parameters are accounted for by ensuring an accurate representation of evaporation rates at temperatures above 273 K. Further, from a sensitivity analysis of all of the data over the full temperature range from 248 to 293 K, we can conclude that the evaporation coefficient of water, and thus the mass accommodation coefficient, is greater than, or equal to, 0.5.

  8. Sediment pore water distribution coefficients of PCB congeners in enriched black carbon sediment.

    PubMed

    Martinez, Andres; O'Sullivan, Colin; Reible, Danny; Hornbuckle, Keri C

    2013-11-01

    More than 2300 sediment pore water distribution coefficients (KPCBi ds) of 93 polychlorinated biphenyls (PCBs) were measured and modeled from sediments from Indiana Harbor and Ship Canal. KPCBi ds were calculated from previously reported bulk sediment values and newly analyzed pore water. PCBs in pore waters were measured using SPME PDMS-fiber and ?PCB ranged from 41 to 1500 ng L(-1). The resulting KPCBi ds were ~1 log unit lower in comparison to other reported values. A simple model for the KPCBi d consisted of the product of the organic carbon fraction and the octanol-water partition coefficient and provided an excellent prediction for the measured values, with a mean square error of 0.09 ± 0.06. Although black carbon content is very high in these sediments and was expected to play an important role in the distribution of PCBs, no improvement was obtained when a two-carbon model was used. PMID:23974165

  9. Temperature and water vapor pressure effects on the friction coefficient of hydrogenated diamondlike carbon films.

    SciTech Connect

    Dickrell, P. L.; Sawyer, W. G.; Eryilmaz, O. L.; Erdemir, A.; Energy Technology; Univ. of Florida

    2009-07-01

    Microtribological measurements of a hydrogenated diamondlike carbon film in controlled gaseous environments show that water vapor plays a significant role in the friction coefficient. These experiments reveal an initial high friction transient behavior that does not reoccur even after extended periods of exposure to low partial pressures of H{sub 2}O and O{sub 2}. Experiments varying both water vapor pressure and sample temperature show trends of a decreasing friction coefficient as a function of both the decreasing water vapor pressure and the increasing substrate temperature. Theses trends are examined with regard to first order gas-surface interactions. Model fits give activation energies on the order of 40 kJ/mol, which is consistent with water vapor desorption.

  10. Improvement of the Performance for an Absorption Refrigeration System with Lithium bromide-water as Refrigerant by Increasing Absorption Pressure

    E-print Network

    Xie, G.; Sheng, G.; Li, G.; Pan, S.

    2006-01-01

    of the performance of an absorption refrigeration cycle using Lithium bromide-water as refrigerant. IIR-IHACE2006, 2006. (In Chinese) [2] Yuqing Zheng, Jinfa Wu, Double effects Chiller using Lithium-bromide with water solution as refrigerant and its application...

  11. Watching Hydrogen Bonds Break: A Transient Absorption Study of Water

    PubMed Central

    Steinel, Tobias; Asbury, John B.; Zheng, Junrong

    2008-01-01

    Ultrafast infrared transient absorption measurements of the complete hydroxyl OD stretching mode spectrum of HOD in water, from 100 fs to tens of picoseconds, observe hydrogen bond breaking and monitor the equilibration of the hydrogen bond network in water. In addition, the vibrational lifetime, the time constant for hydrogen bond breaking, and the rate of orientational relaxation are determined. The reactant and photoproduct spectra of the hydrogen bond breaking process are identified by decomposing the transient spectra into two components, the initial spectrum associated with vibrational excited states (reactants) and the long-time spectrum associated with broken hydrogen bonds (photoproducts). By properly taking into account the perturbation of the reactant spectrum decay by the growth of the photoproduct spectrum, it is found that the vibrational relaxation (1.45 ps) and orientational relaxation (1.53 ps) are wavelength independent and, therefore, independent of the degree of hydrogen bonding. Energy deposited into water by vibrational relaxation does not immediately break a hydrogen bond by predissociation nor produce a thermally equilibrated hydrogen bond distribution at an elevated temperature. Following deposition of energy by vibrational relaxation, the hydrogen bond breaking time is 800 fs, and there is a transient period of several picoseconds during which the hydrogen bond distribution is not in thermal equilibrium. PMID:19096727

  12. AN AMMONIA-WATER ABSORPTION-HIAT-PUMP CYCLE Donald Kuhlenschmidt, Member ASHRAE

    E-print Network

    Oak Ridge National Laboratory

    #12;AN AMMONIA-WATER ABSORPTION-HIAT-PUMP CYCLE BY Donald Kuhlenschmidt, Member ASHRAE Richard H and Research of Arkla Industries Inc., Evansville, Indiana. #12;INTRODUCTION The ammonia-water absorption cycle and the chilled water returns to the cycle at 12.8 0 C(55F). Several things became apparent at the outset: 1

  13. Centrifugal Partition Chromatography. V. Octanol-Water Partition Coefficients, Direct and Indirect Determination

    Microsoft Academic Search

    Alain Berthod; Yoon Il Han; Daniel W. Armstrong

    1988-01-01

    Octanol-water partition coefficients (Koct) are one of the accepted physico-chemical parameters for predicting the biological effects of organic chemicals. It is demonstrated that centrifugal partition chromatography (CPC) can be used to determine directly the Koct values from about 0.003 to 300. The mobile phase must be water and the stationary phase must be octanol for accurate determination of the larger

  14. Effects of laser energy density on impulse coupling coefficient of laser ablation of water for propulsion

    Microsoft Academic Search

    C. Y. Cui; Y. J. Hong; J. F. Ye; M. Wen; N. L. Li

    2011-01-01

    Time-resolved force sensing and intensified charge-coupled device (ICCD) imaging techniques were applied to the study of the effects of laser energy density on impulse coupling coefficient of laser ablation of water for propulsion. A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 mum, 30 J pulse energy was used to ablate water contained in a quadrate quartz

  15. Measurement of the water-octanol partition coefficient of 2,3,7,8-tetrachlorodibenzo-p-dioxin

    Microsoft Academic Search

    Leland Marple; Bernard Berridge; Lewis Throop

    1986-01-01

    The problems inherent in the shake flask method for measurement of water-octanol partition coefficients were avoided by the use of a cell in which dioxin was allowed to diffuse from the octanol phase into the water phase. Starting from mutually presaturated water and octanol phases, dioxin equilibration appears to be complete within 1 week. Partition coefficients ranged from 3.48 x

  16. Modeling the Water-R134a Partition Coefficients of Organic Solutes Using a Linear Solvation Energy Relationship

    E-print Network

    Lagalante, Anthony F.

    Modeling the Water-R134a Partition Coefficients of Organic Solutes Using a Linear Solvation Energy solvation energy relationship (LSER) was developed to predict the measured water-R134a partitionVed: June 23, 1998; In Final Form: August 17, 1998 The water-R134a partition coefficients for a set of 11

  17. PREDICTION OF OCTANOL/WATER PARTITION COEFFICIENT (KOW) WITH ALGORITHMICALLY DERIVED VARIABLES

    EPA Science Inventory

    A statistical model was developed with algorithmically derived independent variables based on chemical structure for prediction of octanol/water partition coefficients (Kow) measured for more than 4,000 chemicals. he procedure first classified the chemicals into 14 groups based o...

  18. Improvement of the variable storage coefficient method with water surface gradient as a variable

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The variable storage coefficient (VSC) method has been used for streamflow routing in continuous hydrological simulation models such as the Agricultural Policy/Environmental eXtender (APEX) and the Soil and Water Assessment Tool (SWAT) for more than 30 years. APEX operates on a daily time step and ...

  19. EQUILIBRIUM DISTRIBUTION COEFFICIENTS FOR EXTRACTION OF ORGANIC PRIORITY POLLUTANTS FROM WATER - II

    EPA Science Inventory

    This report is the second of a series of two reports dealing with the removal of certain of the organic EPA Priority Pollutants from water by means of solvent extraction. The principal focus of the project has been measurement of equilibrium distribution coefficients (equivalent ...

  20. Diffusion coefficients of water in biobased hydrogel polymer matrices by nuclear magnetic resonance imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The diffusion coefficient of water in biobased hydrogels were measured utilizing a simple NMR method. This method tracks the migration of deuterium oxide through imaging data that is fit to a diffusion equation. The results show that a 5 wt% soybean oil based hydrogel gives aqueous diffusion of 1.37...

  1. Direct calculation of 1-octanol-water partition coefficients from adaptive biasing force molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Navendu; Kamath, Ganesh; Chelst, Issac; Potoff, Jeffrey J.

    2012-07-01

    The 1-octanol-water partition coefficient log Kow of a solute is a key parameter used in the prediction of a wide variety of complex phenomena such as drug availability and bioaccumulation potential of trace contaminants. In this work, adaptive biasing force molecular dynamics simulations are used to determine absolute free energies of hydration, solvation, and 1-octanol-water partition coefficients for n-alkanes from methane to octane. Two approaches are evaluated; the direct transfer of the solute from 1-octanol to water phase, and separate transfers of the solute from the water or 1-octanol phase to vacuum, with both methods yielding statistically indistinguishable results. Calculations performed with the TIP4P and SPC/E water models and the TraPPE united-atom force field for n-alkanes show that the choice of water model has a negligible effect on predicted free energies of transfer and partition coefficients for n-alkanes. A comparison of calculations using wet and dry octanol phases shows that the predictions for log Kow using wet octanol are 0.2-0.4 log units lower than for dry octanol, although this is within the statistical uncertainty of the calculation.

  2. Comparison of activity coefficient models for atmospheric aerosols containing mixtures of electrolytes, organics, and water

    NASA Astrophysics Data System (ADS)

    Tong, Chinghang; Clegg, Simon L.; Seinfeld, John H.

    Atmospheric aerosols generally comprise a mixture of electrolytes, organic compounds, and water. Determining the gas-particle distribution of volatile compounds, including water, requires equilibrium or mass transfer calculations, at the heart of which are models for the activity coefficients of the particle-phase components. We evaluate here the performance of four recent activity coefficient models developed for electrolyte/organic/water mixtures typical of atmospheric aerosols. Two of the models, the CSB model [Clegg, S.L., Seinfeld, J.H., Brimblecombe, P., 2001. Thermodynamic modelling of aqueous aerosols containing electrolytes and dissolved organic compounds. Journal of Aerosol Science 32, 713-738] and the aerosol diameter dependent equilibrium model (ADDEM) [Topping, D.O., McFiggans, G.B., Coe, H., 2005. A curved multi-component aerosol hygroscopicity model framework: part 2—including organic compounds. Atmospheric Chemistry and Physics 5, 1223-1242] treat ion-water and organic-water interactions but do not include ion-organic interactions; these can be referred to as "decoupled" models. The other two models, reparameterized Ming and Russell model 2005 [Raatikainen, T., Laaksonen, A., 2005. Application of several activity coefficient models to water-organic-electrolyte aerosols of atmospheric interest. Atmospheric Chemistry and Physics 5, 2475-2495] and X-UNIFAC.3 [Erdakos, G.B., Change, E.I., Pandow, J.F., Seinfeld, J.H., 2006. Prediction of activity coefficients in liquid aerosol particles containing organic compounds, dissolved inorganic salts, and water—Part 3: Organic compounds, water, and ionic constituents by consideration of short-, mid-, and long-range effects using X-UNIFAC.3. Atmospheric Environment 40, 6437-6452], include ion-organic interactions; these are referred to as "coupled" models. We address the question—Does the inclusion of a treatment of ion-organic interactions substantially improve the performance of the coupled models over that of the decoupled models? Performance is judged by the extent to which each model is able to reproduce experimental water activity data for mixtures of organic acids (malonic, succinic, glutaric, citric, maleic, and malic acids) and inorganic electrolytes (NaCl and (NH 4) 2SO 4). It is found, based on the comparisons reported here, that the decoupled models perform as well as, and in some cases better than, the coupled models. Since such activity coefficient models are likely to continue to be developed in the future and because we consider here only a limited set of organic compounds, the current study should be viewed as an interim assessment. The scarcity of experimental data for mixtures of atmospheric relevance remains a limitation for testing activity coefficient models.

  3. Temperature dependence of diffusion coefficient of nitrogen gas in water: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Sharma, Keshav; Adhikari, Narayan P.

    2014-04-01

    We have carried out the molecular dynamics (MD) simulation to study the structural properties and to estimate the diffusivity of molecular nitrogen (N2) gas (solute) in extended simple point charge model (SPC/E) water (solvent) with N2 mole fraction of 0.018 at different temperatures. For the structural properties of the system, we have determined radial distribution function (RDF). The solute-solute, solute-solvent and solvent-solvent RDF have been evaluated. Self-diffusion coefficient of N2 was estimated by evaluating mean-squared displacement (MSD) and velocity autocorrelation function (VACF) separately. The diffusion coefficients obtained from the two methods agree within 3%. The results are in agreement with the experimentally determined values within 10%. The self-diffusion coefficient of water (H2O) was also estimated by evaluating MSD. Mutual diffusion coefficient of the system have also been estimated invoking Darken's relation. The temperature dependance of the diffusion coefficients were found to follow Arrhenius relation.

  4. Broadband Measurement of Black Carbon Absorption and Scattering Coefficients using a Supercontinuum Integrated Photoacoustic and Nephelometer Instrument

    NASA Astrophysics Data System (ADS)

    sharma, N.; Arnold, I. J.; Moosmuller, H.; Arnott, P.; Mazzoleni, C.

    2012-12-01

    The study of light absorbing and scattering properties of atmospheric aerosols is necessary for predicting the effects of aerosols on the climate. Integrated photoacoustic-nephelometer spectrometers are commonly used for simultaneous measurement of light absorption and scattering from atmospheric aerosol particles. Commercially available photoacoustic-nephelometer instruments use one to three discrete operating wavelengths. The optical properties of some aerosol particles vary with the aerosol composition, and exhibit unique wavelength dependencies, especially for biomass burning and mineral dust aerosols. Additionally, atmospheric processes like mixing and aging change the aerosol optical properties. Therefore, there is a need to characterize the aerosol optical properties at more than a few discrete wavelengths. Using a light source which spans a wide and continuous wavelength range in combination with photoacoustic spectrometer and nephelometer techniques would facilitate the study of the optical behavior of aerosols over the solar spectrum. In the environmental optics laboratory at Michigan Technological University and in collaboration with the Desert Research Institute in Reno, Nevada, we are developing a new integrated photoacoustic-nephelometer spectrometer that uses a supercontinuum laser as light source. The emission of the supercontinuum laser continuously covers the entire visible spectrum and part of the infrared spectrum (i.e., from 400nm to 2200nm) and should therefore allow characterizing the aerosol optical properties over almost the entire solar spectrum. Currently, our focus is on studying the aerosol optical properties of combustion aerosol in the visible part of the spectrum (i.e., 400-700nm). The current prototype uses a filter wheel with bandpass optical filters of wavelength 417nm (bandwidth 60nm), 475nm (bandwidth 64nm), 542nm (bandwidth 50nm), 607nm (bandwidth 70nm) and 675nm (bandwidth 67nm). In July 2012 we performed a laboratory study at the Desert Research Institute, measuring absorption and scattering coefficients of kerosene soot and sodium chloride aerosols. As a reference system we used a commercial three-wavelength photoacoustic-nephelometer instrument (DMT Inc.). Here, we present the results of this laboratory intercomparison.

  5. Salting-out phenomenon and 1-octanol/water partition coefficient of metalaxyl pesticide.

    PubMed

    Saab, J; Bassil, G; Abou Naccoul, R; Stephan, J; Mokbel, I; Jose, J

    2011-02-01

    In this paper, we present the effect of inorganic cations such as Na+, K+, Ca2+, Mg2+ on the salting-out phenomenon of metalaxyl from pure water to aqueous salt solutions. Moreover the 1-octanol/water partition coefficient in pure water is presented. To accomplish this, aqueous solubility of metalaxyl was determined in pure water, in different salt solution (NaCl, KCl, CaCl2 and MgCl2), and at different concentration level ranging from 0.01 to 1.5 M. The 1-octanol/water partition coefficient was determined using the static shake-flask method. Solubility was determined using dynamic saturation method for pure water in the range of 298.15-325.15 K and at 298.15 K for different salt solutions. The solubility value in pure water for studied interval was found constant (m=3.118×10(-2) mol kg(-1)). Solubility values were used to calculate the standard molar Gibbs free energy of dissolution (?solG°) and transfer (?trG°) at 298.15 K. The values of ?trG° from pure to all studied aqueous salt solutions did not exceed 2 kJ mol(-1), the value of ?solG° of dissolution is 18.5 ±0.72 kJ mol(-1). The 1-octanol/water partition coefficient in pure water log Ko/w is equal to 1.69. The obtained results confirm the classification of the neutral metalaxyl as a slightly hydrophobic molecule. PMID:21094973

  6. Relation between water solubility, octanol\\/water partition coefficients, and bioconcentration of organic chemicals in fish: a review

    Microsoft Academic Search

    C. A. van Gestel; K. Otermann; J. H. Canton

    1985-01-01

    A survey was made of the literature describing relations between water solubility (S), the octanol-water partition coefficient (Poct), and the bioconcentration factor (BCF) of organic chemicals. Based on the relations between BCF and Poct it can be concluded that mostly BCF is log BCF = 0.79 log Poct-0.40. From relations between Poct and S it can be concluded that for

  7. A comprehensive study of diffusion, thermodiffusion, and Soret coefficients of water-isopropanol mixtures.

    PubMed

    Mialdun, A; Yasnou, V; Shevtsova, V; Königer, A; Köhler, W; Alonso de Mezquia, D; Bou-Ali, M M

    2012-06-28

    We report on the measurement of diffusion (D), thermodiffusion (D(T)), and Soret (S(T)) coefficients in water-isopropanol mixtures by three different instrumental techniques: thermogravitational column in combination with sliding symmetric tubes, optical beam deflection, and optical digital interferometry. All the coefficients have been measured over the full concentration range. Results from different instruments are in excellent agreement over a broad overlapping composition (water mass fraction) range 0.2 < c < 0.7, providing new reliable benchmark data. Comparison with microgravity measurements (SODI/IVIDIL (Selected Optical Diagnostic Instrument/Influence of VIbration on DIffusion in Liquids)) onboard the International Space Station and with literature data (where available) generally gives a good agreement. Contrary to theoretical predictions and previous experimental expectations we have not observed a second sign change of S(T) at low water concentrations. PMID:22755592

  8. Forecasting runoff coefficients using ANN for water resources management: The case of Notwane catchment in Eastern Botswana

    Microsoft Academic Search

    B. P. Parida; D. B. Moalafhi; P. K. Kenabatho

    2006-01-01

    Forecasting future response behaviour of a semi-arid catchment in terms of runoff coefficient being trivial, an attempt has been made to apply an artificial neural network (ANN) model to forecast the runoff coefficients (ROC) for the rapidly urbanizing Notwane catchment system in Botswana. Runoff coefficients computed from 1978 to 2000, by the water balance technique have been used to develop

  9. Light absorption and partitioning in Arctic Ocean surface waters: impact of multi year ice melting

    NASA Astrophysics Data System (ADS)

    Bélanger, S.; Cizmeli, S. A.; Ehn, J.; Matsuoka, A.; Doxaran, D.; Hooker, S.; Babin, M.

    2013-03-01

    Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie river-influenced waters and polar mixed layer waters. We found that melting multi-year ice released significant amount of non-algal particulates (NAP) near the sea surface relative to sub-surface waters. NAP absorption coefficients at 440 nm (aNAP(440)) immediately below the sea surface (0-) were on average 3-fold (up to 10-fold) higher compared to sub-surface values measured at 2-3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs) was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR) by ~6% and ~8%, respectively, relative to a fully homogenous water column with low particles concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400-550 nm). These results highlight the impact of melt water on the concentration of particles at sea surface, and the need for considering nonuniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM photobleaching).

  10. EXPERIMENTAL STUDY OF THE ABSORPTION IN DISTILLED WATER, ARTIFICIAL SEA WATER, AND HEAVY WATER IN THE VISIBLE REGION OF THE SPECTRUM

    Microsoft Academic Search

    SERAPHIN A. SULLIVAN

    1963-01-01

    The absorption of light in distilled water, artificial sea water, and ; heavy water was measured in the visible region. A Nielsen spectrometer with ; glass optics was used with a tungsten source and photomultiplier detector. Path ; lengths were 60.0 and 132.0 cm. The absorption in distilled and artificiai sea ; water differs little; maxima below 745 m mu

  11. Comparison of reflectance with backscatter and absorption parameters for turbid waters

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Poole, L. R.; Usry, J. W.; Houghton, W. M.; Witte, W. G.; Morris, W. D.; Gurganus, E. A.

    1981-01-01

    The relation of reflectance to backscatter and absorption parameters is investigated for waters more turbid than those of previous investigations. Experimental data are examined for river waters in which beam attenuation values range from 8.9 to 18.9 per m at 550 nm. Attenuation, absorption, backscatter, and irradiance reflectance spectral properties are presented for wavelengths between 450 and 800 nm. Comparisons of reflectance with backscatter to absorption ratio and backscatter with absorption plus backscatter ratio indicate that data for turbid waters do not fit linear or polynomial models which are presently available in the literature.

  12. N-OCTANOL/WATER PARTITION COEFFICIENTS BY REVERSE PHASE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY FOR EIGHT TETRACHLORINATED PLANAR MOLECULES

    EPA Science Inventory

    In understanding and modeling the toxicological and pharmacokinetic properties of organic chemicals, physical-chemical properties such as aqueous solubilities, vapor pressures, and n-octanol/water partition coefficients are required. Currently, the octanol/water partition coeffic...

  13. High-resolution spectra and photoabsorption coefficients for carbon monoxide absorption bands between 94.0 nm and 100.4 nm

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Stark, G.; Smith, P. L.; Parkinson, W. H.; Ito, K.

    1988-01-01

    Photoabsorption coefficients have been measured for the CO in interstellar clouds at a resolving power more than 20 times greater than previously obtainable. In order to facilitate comparisons, these data have been integrated over the same wavelength ranges as used in Letzelter et al. (1987). It is found that most of the results obtained for bands between 94.0 and 100.4 nm are larger than those of Letzelter; the discrepancy may be attributable to the difference between the resolving powers of the spectrometers used, because the saturation effects associated with low resolution can underestimate absorption coefficient values.

  14. Evaluating Some Empirical Models for Predicting Water Absorption in African Breadfruit (Treculia Africana) Seeds

    Microsoft Academic Search

    T. A. Shittu; S. O. Awonorin; A. O. Raji

    2004-01-01

    Water absorption process during soaking of African breadfruit (ABF) seeds was studied at five typical soaking temperatures, ranging between 30 and 70°C. The progress of water absorption by the seeds followed an exponential increase with increase in temperature. The experimental data were fitted to three empirical equations. All the equations were able to explain over 90% of the experimental data.

  15. Light absorption and partitioning in Arctic Ocean surface waters: impact of multiyear ice melting

    NASA Astrophysics Data System (ADS)

    Bélanger, S.; Cizmeli, S. A.; Ehn, J.; Matsuoka, A.; Doxaran, D.; Hooker, S.; Babin, M.

    2013-10-01

    Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie River-influenced waters and polar mixed layer waters. We found that melting multiyear ice released significant amount of non-algal particulates (NAP) near the sea surface relative to subsurface waters. NAP absorption coefficients at 440 nm (aNAP(440)) immediately below the sea surface were on average 3-fold (up to 10-fold) higher compared to subsurface values measured at 2-3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs) was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR) by ∼6 and ∼8%, respectively, relative to a fully homogenous water column with low particle concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400-550 nm). These results highlight the impact of meltwater on the concentration of particles at sea surface, and the need for considering non-uniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV (ultraviolet) domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM (particulate organic matter) photobleaching).

  16. Screening of octanol–water partition coefficients for pharmaceuticals by pressure-assisted microemulsion electrokinetic chromatography

    Microsoft Academic Search

    Zhongjiang Jia; Lijie Mei; Fangling Lin; Sujuan Huang; Robert B. Killion

    2003-01-01

    A rapid screening assay for the determination of octanol–water partition coefficients (log Pow) of pharmaceuticals was developed by using pressure-assisted microemulsion electrokinetic chromatography (MEEKC). The microemulsion system contains 50 mM sodium dodecyl sulfate, 0.87 M 1-butanol, 82 mM heptane, and 50 mM borate–phosphate (2:3) at pH 10. Ten standard compounds with known log Pow values from ?0.26 to 4.88 were

  17. Estimation of Octanol-Water Partition Coefficient of Chloride Hydrocarbon by Group Contribution Method

    Microsoft Academic Search

    Yinghua LIANG; Hongping CHEN

    2007-01-01

    A novel method named two-level group contribution (GC-K) method for the estimation of octanol-water partition coefficient (Kow) of chloride hydrocarbon is presented. The equation includes only normal boiling points and molecular weight of compounds. Group contribution parameters of 12 first-level groups and 7 second-level groups for Kow are obtained by correlating experimental data of three types including 57 compounds. By

  18. Predicting 1-octanol-water partition coefficient by high-performance liquid chromatography gradient elution

    Microsoft Academic Search

    A. Kaune; M. Knorrenschild; A. Kettrup

    1995-01-01

    The method to predict 1-octanol-water partition coefficients (Kow) from capacity factors (k') obtained by Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) has been extended to use gradient elution rather than isocratic elution. The mobile phase has been changed either linearly or exponentially with time. The initial composition of the mobile phase and its rate of change affected the log Kow versus log

  19. Improved method estimating bioconcentration\\/bioaccumulation factor from octanol\\/water partition coefficient

    Microsoft Academic Search

    William M. Meylan; Philip H. Howard; D. Aronson; H. Printup; S. Gouchie; R. S. Boethling

    1999-01-01

    A compound`s bioconcentration factor (BDF) is the most commonly used indicator of its tendency to accumulate in aquatic organisms from the surrounding medium. Because it is expensive to measure, the BCF is generally estimated from the octanol\\/water partition coefficient (K{sub ow}), but currently used regression equations were developed from small data sets that do not adequately represent the wide range

  20. QSPR models for polychlorinated biphenyls: n-Octanol\\/water partition coefficient

    Microsoft Academic Search

    J. Padmanabhan; R. Parthasarathi; V. Subramanian; P. K. Chattaraj

    2006-01-01

    The logarithmic n-octanol\\/water partition coefficient (logKow) is an important property for pharmacology, toxicology and medicinal chemistry. Quantitative structure–property relationship (QSPR) model for the lipophilic behaviour (logKow) of the data set containing 133 polychlorinated biphenyl (PCB) congeners is analyzed using the conceptual density functional theory based global reactivity parameter such as electrophilicity index (?) along with energy of lowest unoccupied molecular

  1. Prediction of octanol-water partition coefficients using a group contribution solvation model

    Microsoft Academic Search

    Shiang-Tai Lin; Stanley I. Sandler

    1999-01-01

    Using the recently derived group contribution solvation (GCS) model, the authors have developed a predictive model for the octanol-water partition coefficient (K{sub OW}), the GCSKOW model. In this model K{sub OW} is calculated from two molecular structure parameters, which take into account the size and shape effects, and one energy parameter that determines the attractive interactions between the solute and

  2. New magnetic nano-absorbent for the determination of n-octanol\\/water partition coefficients

    Microsoft Academic Search

    X. Gao; C. H. Yu; K. Y. Tam; S. C. Tsang

    2005-01-01

    A novel and generic miniaturization methodology for the determination of partition coefficient values of organic compounds in n-octanol\\/water by using magnetic nanoparticles is, for the first time, described. We have successfully designed, synthesised and characterised new colloidal stable porous silica-encapsulated magnetic nanoparticles of controlled dimensions. These nanoparticles absorbing a tiny amount of n-octanol in their porous silica over-layer are homogeneously

  3. Activity coefficients for NH 4Cl in ethanol–water mixed solvents by electromotive force measurements

    Microsoft Academic Search

    Farzad Deyhimi; Bahram Ghalami-Choobar; Rahman Salamat-Ahangari

    2005-01-01

    Pitzer ion-interaction model and electromotive force (emf) data of a galvanic cell without liquid junction were used for the determination of activity coefficients of NH4Cl in different ethanol–water mixed solvents at 25 °C. The used galvanic cell is schematically represented by: Ag?AgCl?NH4Cl (m), H2O (100-w%), EtOH (w%)?NH4+ (ISE), in which ISE stands for ion-selective electrode and w for the mass

  4. Determination of the carrier concentration in CdSe crystals from the effective infrared absorption coefficient measured by means of the photothermal infrared radiometry

    NASA Astrophysics Data System (ADS)

    Pawlak, M.

    2015-01-01

    In this paper, a non-contact method that allows to determine the carrier concentration in CdSe crystals is presented. The method relies on the measurement of the effective infrared absorption coefficient by means of the photothermal infrared radiometry (PTR). In order to obtain the effective infrared absorption coefficient and thermal diffusivity, the frequency characteristics of the PTR signal were analyzed in the frame of a one-dimensional heat transport model for infrared semitransparent crystals. The carrier concentrations were estimated using a theory introduced by Ruda and a recently proposed normalization procedure for the PTR signal. The deduced carrier concentrations of the investigated CdSe crystals are in reasonable agreement with those obtained using Hall measurements and infrared spectroscopy. The method presented in this paper can also be applied to other semiconductors with the carrier concentration in the range of 1014-1017 cm-3.

  5. Resonant effects in the manifestation of hybridized electronic states of iron impurities in the temperature dependences of the absorption coefficient and velocity of ultrasound propagation in mercury selenide

    NASA Astrophysics Data System (ADS)

    Okulov, V. I.; Gudkov, V. V.; Govorkova, T. E.; Zhevstovskikh, I. V.; Lonchakov, A. T.; Paranchich, S. Yu.

    2007-11-01

    The temperature dependences of the absorption coefficient and phase velocity of 52-MHz ultrasonic waves in iron-doped mercury selenide crystals are studied. The presence of impurities in concentrations of about 1019 cm-3 is found to initiate the appearance of a resonance peak in the absorption coefficient at a temperature of about 5 K and the corresponding anomaly in the velocity of the slow transverse wave propagating in the <110> direction. It is shown that the observed effects can be accounted for by the interaction of ultrasound with electrons in the states created in hybridization of the iron impurity donor states with the conduction band states of the crystal. A straightforward theoretical description and quantitative interpretation of these effects are proposed and used to derive data on the hybridized states, which conform with the earlier treatment of the temperature and concentration anomalies of conductivity in the crystals under study.

  6. THEORETICAL STUDY OF OPTICAL PROPERTIES. PHOTON ABSORPTION COEFFICIENTS, OPACITIES, AND EQUATIONS OF STATE OF LIGHT ELEMENTS INCLUDING THE EFFECT OF LINES. Final Report. APPENDIX A: THERMODYNAMIC PROPERTIES AND MEAN OPACITIES

    Microsoft Academic Search

    J. C. Stewart; K. D. Jr. Pyatt

    1961-01-01

    Photon absorption coefficients and mean opacities were calculated for ; hydrogen, beryllium, carbon, nitrogen, aluminum, and silicon over a temperature ; range froni l.5 to 34 ev and a density range from about l0⁻¹g\\/cm³ ; downward. Contributions to the absorption coefficient from free-free (inverse-; bremsstrahlung), bound-free (photoelectric), and bound-bound (line-absorption) ; processes are included, as is Compton scattering. Certain thermodynamic

  7. K-shell absorption jump factors and jump ratios in elements between Tm ( Z = 69) and Os ( Z = 76) derived from new mass attenuation coefficient measurements

    Microsoft Academic Search

    Necati Kaya; Engin Tirasoglu; Gökhan Apaydin; Volkan Aylikci; Erhan Cengiz

    2007-01-01

    The K-shell absorption jump factors and jump ratios were derived from new mass attenuation coefficients measured using an energy dispersive X-ray fluorescence (EDXRF) spectrometer for Tm, Yb elements being Tm2O3, Yb2O3 compounds and pure Lu, Hf, Ta, W, Re and Os. The measurements, in the region 56–77keV, were done in a transmission geometry utilizing the K?1, K?2, K?1 and K?2

  8. Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV

    Microsoft Academic Search

    P. D. Higgins; F. H. Attix; J. H. Hubbell; S. M. Seltzer; M. J. Berger

    1991-01-01

    Mass energy transfer (Mu sub u Rho) and mass energy absorption coefficients (Mu sub en Rho) are tabulated in units of sq. cm\\/g for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general dosimetric interest. Cross sections for photo-effect, incoherent scattering, and pair and triplet production are those

  9. Characterizing the vertical diffuse attenuation coefficient for downwelling irradiance in coastal waters: Implications for water

    E-print Network

    Rundquist, Donald C.

    waters: Implications for water penetration by high resolution satellite data Deepak R. Mishra a,, Sunil body comes from a surface layer of water of depth 1/Kd, the results showed that a typical satellite sensor (such as IKONOS) can penetrate up to 8 m in the blue band, 6 m in green, and 2 m in the red region

  10. Diffusion coefficients for hydrogen sulfide, carbon dioxide, and nitrous oxide in water over the temperature range 293--368 K

    Microsoft Academic Search

    A. Tamimi; Edward B. Rinker; Orville C. Sandall

    1994-01-01

    Acid gases such as H[sub 2]S and CO[sub 2] are generally removed from natural gas, biogas, synthetic natural gas, and other process gas streams by means of absorption into aqueous alkanolamine solutions. A key parameter needed to model this diffusion with chemical reaction process in the liquid phase is the diffusion coefficient. A wetted-sphere absorption apparatus was used to measure

  11. Lipid-water partition coefficients and correlations with uptakes by algae of organic compounds.

    PubMed

    Hung, Wei-Nung; Chiou, Cary T; Lin, Tsair-Fuh

    2014-08-30

    In view of the scarcity of the lipid-water partition coefficients (Ktw) for organic compounds, the logKtw values for many environmental contaminants were measured using ultra-pure triolein as the model lipid. Classes of compounds studied include alkyl benzenes, halogenated benzenes, short-chain chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides. In addition to logKtw determination, the uptakes of these compounds from water by a dry algal species were measured to evaluate the lipid effect on the algal uptake. The measured logKtw are closely related to their respective logKow (octanol-water), with logKow=1.9 to 6.5. A significant difference is observed between the present and early measured logKtw for compounds with logKow>?5, which is attributed to the presence and absence of a triolein microemulsion in water affecting the solute partitioning. The observed lipid-normalized algae-water distribution coefficients (logKaw/lipid) are virtually identical to the respective logKtw values, which manifests the dominant lipid-partition effect of the compounds with algae. PMID:25064256

  12. Temperature Dependences of Mechanisms Responsible for the Water-Vapor Continuum Absorption

    NASA Technical Reports Server (NTRS)

    Ma, Qiancheng

    2014-01-01

    The water-vapor continuum absorption plays an important role in the radiative balance in the Earth's atmosphere. It has been experimentally shown that for ambient atmospheric conditions, the continuum absorption scales quadratically with the H2O number density and has a strong, negative temperature dependence (T dependence). Over the years, there have been three different theoretical mechanisms postulated: far-wings of allowed transition lines, water dimers, and collision-induced absorption. The first mechanism proposed was the accumulation of absorptions from the far-wings of the strong allowed transition lines. Later, absorption by water dimers was proposed, and this mechanism provides a qualitative explanation for the continuum characters mentioned above. Despite the improvements in experimental data, at present there is no consensus on which mechanism is primarily responsible for the continuum absorption.

  13. Determination of the brain-blood partition coefficient for water in mice using MRI.

    PubMed

    Leithner, Christoph; Müller, Susanne; Füchtemeier, Martina; Lindauer, Ute; Dirnagl, Ulrich; Royl, Georg

    2010-11-01

    Cerebral blood flow (CBF) quantification is a valuable tool in stroke research. Mice are of special interest because of the potential of genetic engineering. Magnetic resonance imaging (MRI) provides repetitive, noninvasive CBF quantification. Many MRI techniques require the knowledge of the brain-blood partition coefficient (BBPC) for water. Adopting an MRI protocol described by Roberts et al (1996) in humans, we determined the BBPC for water in 129S6/SvEv mice from proton density measurements of brain and blood, calibrated with deuterium oxide/water phantoms. The average BBPC for water was 0.89 ± 0.03 mL/g, with little regional variation within the mouse brain. PMID:20842161

  14. Exponential sum absorption coefficients of phosphine from 2750 to 3550 cm-1 for application to radiative transfer analyses on Jupiter and Saturn

    NASA Astrophysics Data System (ADS)

    Temma, T.; Baines, K. H.; Butler, R. A. H.; Brown, L. R.; Sagui, L.; Kleiner, I.

    2006-12-01

    PH3 exponential sum k coefficients were computed between 2750 and 3550 cm-1 (2.82-3.64 ?m), in view of future application to radiative transfer analyses of Jupiter and Saturn in a phosphine absorption band near 3 ?m. The temperature and pressure of this data set cover the ranges from 80 to 350 K and from 10-3 to 101 bars, respectively. Transmission uncertainty incurred by the use of the k coefficients is smaller than a few percent as long as the radiation is confined above an altitude of a few bars in the giant planets. In spectral regions of weak absorption at high pressures close to 10 bars, contributions from far wings of strong absorption lines must be carefully taken into account. Our data set helps map the three-dimensional distribution of PH3 on the giant planets, revealing their global atmospheric dynamics extending down to the deep interior. The complete k coefficient data set of this work is available at the Web site of the NASA Planetary Data System Atmospheres Node.

  15. Determination of infinite dilution activity coefficients and 1-octanol\\/water partition coefficients of volatile organic pollutants

    Microsoft Academic Search

    Ginger Tse; Stanley I. Sandler

    1994-01-01

    The characterization of pollutants is of growing interest as concerns about the environment increase. One parameter useful in predicting the fate of a chemical in the environment, the infinite dilution activity coefficient, has been determined here for several EPA priority pollutants in 1-octanol at 25 C using a relative gas-liquid chromatographic measurement technique. A simple correlation has been developed relating

  16. Quasi-random narrow-band model fits to near-infrared low-temperature laboratory methane spectra and derived exponential-sum absorption coefficients

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; West, Robert A.; Giver, Lawrence P.; Moreno, Fernando

    1993-01-01

    Near-infrared 10/cm resolution spectra of methane obtained at various temperatures, pressures, and abundances are fit to a quasi-random narrow-band model. Exponential-sum absorption coefficients for three temperatures (112, 188, and 295 K), and 20 pressures from 0.0001 to 5.6 bars, applicable to the cold environments of the major planets, are then derived from the band model for the 230 wavelengths measured from 1.6 to 2.5 microns. RMS deviations between the laboratory and the exponential-sum synthetic transmissions are reported for the best fitting 50 wavelengths. Deviations relevant to broadband, 1-percent spectral resolution observations are also presented. The validity of exponential-sum coefficients derived from broadband (10/cm) transmission data is demonstrated via direct comparison with line-by-line calculations. The complete atlas of coefficients is available from the Planetary Data System-Planetary Atmospheres Discipline Node.

  17. Resonant peaks of the linear optical absorption and rectification coefficients in GaAs/GaAlAs quantum well: Combined effects of intense laser, electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Ozturk, Emine; Sokmen, Ismail

    2015-11-01

    In this study, the resonant peaks of the linear optical absorption (OA) and rectification coefficients in GaAs/GaAlAs quantum well are calculated as dependent on the applied electric field (F), the magnetic field (B) and the laser field intensity parameter (?0). Our results show that the shape of confined potential profile, the energy levels and the dipole moment matrix elements are changed as dependent on the F, B and ?0. Also, the resonant peaks of the OA and rectification coefficients depend on the applied external field effects. Therefore, the variation of the resonant peaks of these coefficients which can be appropriate for various optical modulators and infrared optical device applications can be smoothly obtained by the alteration electric, magnetic and intense laser field.

  18. Development of a UAV-based differential absorption lidar for measuring atmospheric water vapor

    Microsoft Academic Search

    Brian William Thomas

    2003-01-01

    Differential Absorption Lidar (DIAL) is a remote sensing technique useful for making range resolved measurements of chemical species. A water vapor DIAL system was developed for use on a high altitude unmanned air vehicle (UAV), in order to study water vapor distribution in hurricanes. The system uses a diode-pumped Cr:LiSAF laser to probe water vapor absorption lines at or near

  19. Diffusion coefficients of energetic water group ions near Comet Giacobini-Zinner

    NASA Astrophysics Data System (ADS)

    Tan, L. C.; Mason, G. M.; Richardson, I. G.; Ipavich, F. M.

    1993-03-01

    Data from the ultralow-energy charge analyzer and energetic particle anisotropy spectrometer sensors, acquired when the ICE spacecraft flew past Comet Giacobini-Zinner on September 11, 1985, are combined, and a single, self-consistent analysis technique is applied to derive a single-particle spectrum from about 200 to 1600 km/s. This information, together with the deduced bulk flow speed of the ions, is used to calculate a parallel diffusion coefficient in the transition region downstream of the bow wave (2.3 +/- 0.5) x 10 exp 17 sq cm/s; the corresponding scattering mean free path is (6 +/- 1) x 10 exp 4 km. The parallel diffusion coefficient is found to depend on the collision frequency of water group ions with Alfven waves, which are assumed to be propagating parallel (antiparallel) to the magnetic field.

  20. Flow-through PSICAM: a new approach for determining water constituents absorption continuously

    NASA Astrophysics Data System (ADS)

    Wollschläger, Jochen; Grunwald, Maik; Röttgers, Rüdiger; Petersen, Wilhelm

    2013-07-01

    Determination of spectral absorption coefficients in seawater is of interest for biologic oceanographers for various reasons, but faces also several problems, especially if continuous measurements are required. We introduce the flow-through point-source integrating cavity absorption meter (ft-PSICAM) as a new tool for the continuous measurement of spectral absorption coefficients in a range of 400-710 nm. A description of the system is given and its performance in comparison with a conventional PSICAM has been evaluated on two cruises in 2011 in the southern part of the North Sea (German Bight). Furthermore, factors influencing the measurement are discussed. When comparing the data of both systems, a good linear correlation has been found for all wavelengths ( r 2 > 0.91). Deviations between systems were different with respect to the wavelength examined with slopes of linear fits between 1.1 and 1.65 and offsets between -0.1 and 0.01, with the higher values at shorter wavelengths. They were caused mainly due to contamination of the flow-through system during operation by phytoplankton particles. Focus was also laid on the measurement of chlorophyll- a concentrations ([chl- a]) and total suspended matter concentrations ([TSM]) on the basis of absorption coefficient determination. For this, appropriate relationships were established and [chl- a] and [TSM] values were calculated from the relevant ft-PSICAM absorption coefficients. Their progression matches well with the progression of fluorescence and turbidity measurements made in parallel. In conclusion, the ft-PSICAM is successful in measuring spectral absorption coefficients continuously and resolving relative changes in seawater optical properties.

  1. Worldwide data sets constrain the water vapor uptake coefficient in cloud formation

    PubMed Central

    Raatikainen, Tomi; Nenes, Athanasios; Seinfeld, John H.; Morales, Ricardo; Moore, Richard H.; Lathem, Terry L.; Lance, Sara; Padró, Luz T.; Lin, Jack J.; Cerully, Kate M.; Bougiatioti, Aikaterini; Cozic, Julie; Ruehl, Christopher R.; Chuang, Patrick Y.; Anderson, Bruce E.; Flagan, Richard C.; Jonsson, Haflidi; Mihalopoulos, Nikos; Smith, James N.

    2013-01-01

    Cloud droplet formation depends on the condensation of water vapor on ambient aerosols, the rate of which is strongly affected by the kinetics of water uptake as expressed by the condensation (or mass accommodation) coefficient, ?c. Estimates of ?c for droplet growth from activation of ambient particles vary considerably and represent a critical source of uncertainty in estimates of global cloud droplet distributions and the aerosol indirect forcing of climate. We present an analysis of 10 globally relevant data sets of cloud condensation nuclei to constrain the value of ?c for ambient aerosol. We find that rapid activation kinetics (?c > 0.1) is uniformly prevalent. This finding resolves a long-standing issue in cloud physics, as the uncertainty in water vapor accommodation on droplets is considerably less than previously thought. PMID:23431189

  2. The Near Infrared Absorption Spectrum of Water by CRDS Between 1.26-1.70 µm:Complete Empirical Line List and Continuum Absorption

    NASA Astrophysics Data System (ADS)

    Mondelain, Didier; Campargue, Alain; Kassi, Samir; Mikhailenko, Semen

    2014-06-01

    Due to the increasing performances of Airborne- and ground-based spectrometers, a more and more accurate characterization of the water vapor absorption is required. This is especially true in the transparency windows, corresponding to low absorption spectral regions widely used for probing the Earth's atmosphere. State-of-the-art experimental developments are required to fulfill the needs in terms of accuracy of the spectroscopic data. For that purpose, we are using high-sensitivity Continuous Wave Cavity Ring Down Spectroscopy (CW-CRDS) allowing reproducing in laboratory conditions comparable to the atmospheric ones in terms of absorption path length (tens of kilometers), temperature and pressure. From extensive analysis of our CRDS spectra, we have constructed an empirical line list for "natural" water vapor at 296 K in the 5850 7920 cm-1 region including 38 318 transitions of four major water isotopologues (H2 16O, H218O, H217O and HD16O) with an intensity cut-off of 1·10-29 cm/molecule. The list is made mostly complete over the whole spectral region by including a large number of unobserved weak lines with positions calculated using experimentally determined energy levels and intensities obtained from variational calculations. In addition, we provide HD18O and HD 17O lists in the same region for transitions with intensities larger than 1·10-29 cm/molecule. The HD18O and HD17O lists (1 972 lines in total) were obtained using empirical energy levels available in the literature and variational intensities. The global list (40 290 transitions) including the contribution of the six major isotopologues has been adopted for the new edition of the GEISA database in the region. The advantages and drawbacks of our list will be discussed in comparison with the list provided for the same region in the 2012 edition of the HITRAN database. Separate experiments were dedicated to the measurement of the water vapor self-continuum crosssections in the 1.6 µm window by CW-CRDS at different temperatures (from room temperature to 340 K). Due to the weakness of the broadband absorption signal to be measured, very few measurements of the water vapor continuum are available in the NIR windows especially for temperature conditions relevant for our atmosphere. This is in particular the case for the 1.6 µm window where the very few available measurements show a large disagreement. The absorption cross-sections, Cs(?, T), were retrieved for different selected wave numbers from a fit of the absorption coefficients measured in real time during pressure ramps, after subtraction of the contributions of the local water monomer lines and of water adsorbed on the CRDS mirrors. The values measured between 5875 and 6665 cm-1 range between 1.5·10-25 and 2·10-24 cm2 molec-1 atm-1 with a minimum around 6300 cm-1. Overall, our measurements are found in strong disagreement with recent FTS measurements and in a good agreement with the values predicted by the MT CKD2.5 model, except for the temperature dependence in the center of the window which is found significantly smaller than predicted.

  3. Impact of Salinity on the Air-Water Partition Coefficient of Gas Tracers

    SciTech Connect

    Zhong, Lirong; Pope, Gary A.; Evans, John C.; Cameron, Richard J.

    2005-09-01

    The use of a gas partitioning interwell tracer test (PITT) has been proposed as a standard approach to the measurement of field-scale vadose zone water saturation fractions. The accuracy of the saturation measurement is largely dependent on the determination of the air-water partitioning coefficient, K, of the tracers; however, in practice, K is also strongly influenced by the physical and chemical properties of the water. In this study, column tests were conducted to investigate the impact of salinity on tracer partitioning coefficients for two promising gas phase candidate tracers, dibromomethane and dimethylether. Sodium thiosulfate was used as a salinity surrogate. The dynamic K values of the two partitioning tracers were measured for sodium thiosulfate concentrations between 0% and 36% by weight. Methane was used as the non-partitioning tracer for all experiments. K values were found to decrease significantly with increasing sodium thiosulfate concentration. Similar correlations between K values and sodium thiosulfate concentration were found for both of the partitioning tracers tested.

  4. [QSPR study on the lipid-water partition coefficients of dioxins based on DFT].

    PubMed

    Gu, Cheng-Gang; Jiang, Xin; Bian, Yong-Rong; Yu, Gui-Fen

    2008-05-01

    With computational method of density functional theory (DFT), quantified model study of equilibrium partitioning properties of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) between lipid phase of organism (Poecilia reticulata) and water phase was carried out based on quantum chemical and further calculated parameters, namely frontier orbital energies, entropies, traceless quadrupole moments as well as molecular absolute hardness, electronegativities and electrophilicity indices, which all were derived from full geometry optimization of PCDD/Fs. Through multiple linear regression (MLR) analyses, quantitative structure-property relationship (QSPR) was successfully proposed in the form of multi-parameter quadratic function: lgK(hw) = 5.343 - 0.001(S - 125.480)(2) - 0.355(omega - 3.239)(2) + 0.006( Q = - 2.950)(2) - 22.728(eta - 2.365)(2). It was shown that the obtained QSPR had higher goodness of fitting and robustness, determination coefficient and cross-validated correlation coefficient being 0.943 and 0.908 respectively, and it was also provided with ideal interior and exterior predictive abilities so that it could be used for prediction of unknown lipid-water partitioning properties. By comparison, QSPR in this research was superior to that from previous SOFA (solubility parameter for fate analysis) method on the whole. Lipid-water partitioning properties (coefficients) of PCDD/Fs should be mainly related to molecular volume and aryl hydrocarbon molecular interactions determined by charge distribution. To a certain degree, they also might be influenced by potential biotransformation and molecular reactivity. PMID:18624202

  5. Characterization of Bile Acid Absorption across the Unstirred Water Layer and Brush Border of the Rat Jejunum

    PubMed Central

    Wilson, Frederick A.; Dietschy, John M.

    1972-01-01

    We have examined the rate-limiting steps involved in bile acid absorption across the unstirred water layer and lipid cell membrane of the jejunal mucosa. Uptake of the polar bile acid taurocholate is limited solely by the cell membrane since this compound permeates the unstirred water layer more rapidly than the lipid cell membrane and stirring does not enhance uptake. With less polar bile acids which permeate the cell membrane relatively more rapidly, however, the unstirred water layer does exert resistance to mucosal uptake of these compounds. That the unstirred water layer is even more rate limiting to uptake from micellar solutions is indicated by the facts that the rate of bile acid absorption from such solutions is lower than from corresponding monomer solutions, stirring markedly enhances uptake from micellar solutions while increases in viscosity of the incubation media depress uptake and expansion of the micelle size further depresses absorption rates. We also have examined the important question of whether the micelle crosses the brush border intact once it reaches the aqueous-lipid interface. The observations that the calculated permeation rate of the micelle should be extremely low, the rate of mucosal cell uptake plateaus at a constant value when the critical micelle concentration is reached at the aqueous-lipid interface, and the different components of a mixed micelle are taken up at different rates indicate that uptake of the intact micelle does not occur; rather, bile acid absorption must be explained in terms of monomers in equilibrium with the micelle. Finally, after correction of the permeability coefficients of the various bile acids for the unstirred layer resistance the incremental partial molar free energy of solution of the hydroxyl group in the brush border membrane was calculated to equal ?6126 cal·mole?1 indicating that passive diffusion of these compounds occurs through a very polar region of the cell membrane. PMID:4674396

  6. Small effect of water on upper-mantle rheology based on silicon self-diffusion coefficients.

    PubMed

    Fei, Hongzhan; Wiedenbeck, Michael; Yamazaki, Daisuke; Katsura, Tomoo

    2013-06-13

    Water has been thought to affect the dynamical processes in the Earth's interior to a great extent. In particular, experimental deformation results suggest that even only a few tens of parts per million of water by weight enhances the creep rates in olivine by orders of magnitude. However, those deformation studies have limitations, such as considering only a limited range of water concentrations and very high stresses, which might affect the results. Rock deformation can also be understood as an effect of silicon self-diffusion, because the creep rates of minerals at temperatures as high as those in the Earth's interior are limited by self-diffusion of the slowest species. Here we experimentally determine the silicon self-diffusion coefficient DSi in forsterite at 8?GPa and 1,600?K to 1,800?K as a function of water content CH2O from less than 1 to about 800 parts per million of water by weight, yielding the relationship, DSi???(CH2O)(1/3). This exponent is strikingly lower than that obtained by deformation experiments (1.2; ref. 7). The high nominal creep rates in the deformation studies under wet conditions may be caused by excess grain boundary water. We conclude that the effect of water on upper-mantle rheology is very small. Hence, the smooth motion of the Earth's tectonic plates cannot be caused by mineral hydration in the asthenosphere. Also, water cannot cause the viscosity minimum zone in the upper mantle. And finally, the dominant mechanism responsible for hotspot immobility cannot be water content differences between their source and surrounding regions. PMID:23765497

  7. Estimation of n -octanol\\/water partition coefficients of polycyclic aromatic hydrocarbons by quantum chemical descriptors

    Microsoft Academic Search

    Gui-Ning Lu; Xue-Qin Tao; Zhi Dang; Xiao-Yun Yi; Chen Yang

    2008-01-01

    Quantitative structure-property relationship (QSPR) modeling is a powerful approach for predicting environmental behavior\\u000a of organic pollutants with their structure descriptors. This study reports an optimal QSPR model for estimating logarithmic\\u000a n-octanol\\/water partition coefficients (log K\\u000a OW) of polycyclic aromatic hydrocarbons (PAHs). Quantum chemical descriptors computed with density functional theory at B3LYP\\/6-31G(d)\\u000a level and partial least squares (PLS) analysis with optimizing

  8. Temperature dependence of octanol-water partition coefficient for selected chlorobenzenes

    Microsoft Academic Search

    Nisheeth P. Bahadur; Wan-Ying Shiu; David G. B. Boocock; Donald Mackay

    1997-01-01

    The current emphasis on assessing the environmental impact of both industrial and agricultural chemicals has resulted in an increased reliance on the physical and chemical properties of these compounds to predict their environmental behavior. The octanol-water partition coefficients of seven chlorobenzenes (1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene) were measured by a conventional shake-flask, batch-contacting method over the temperature

  9. Direct measurement of octanol–water partition coefficients of some environmentally relevant brominated diphenyl ether congeners

    Microsoft Academic Search

    Eric Braekevelt; Sheryl A Tittlemier; Gregg T Tomy

    2003-01-01

    Octanol–water partition coefficients (KOW) of nine environmentally relevant brominated diphenyl ether (BDE) congeners present in two technical mixtures were directly measured using a slow-stir technique. LogKOW values of tri- to heptabrominated BDE congeners ranged from 5.74 to 8.27, and were related to bromine content by the equation logKOW=0.621(#Br)+4.12(R2=0.970). The directly determined KOW values were generally lower than those calculated using

  10. Mass-specific optical absorption coefficients and imaginary part of the complex refractive indices of mineral dust components measured by a multi-wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2015-01-01

    Mass-specific optical absorption coefficients (MACs) and the imaginary part (?) of the refractive indices of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at the wavelengths of 1064, 532, 355 and 266 nm. The MAC values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. Values of ? were calculated from the measured and particle-loss-corrected data by using a Mie-theory-based retrieval algorithm. The determined values could be used for comparisons with calculated wavelength-dependent ? values typically deduced from bulk-phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk-phase measurements.

  11. Absorption spectrum (380–700 nm) of pure water. II. Integrating cavity measurements

    Microsoft Academic Search

    Robin M. Pope; Edward S. Fry

    1997-01-01

    Definitive data on the absorption spectrum of pure water from 380 to 700 nm have been obtained with an integrating cavity technique. The results are in good agreement with those recently obtained by our group with a completely independent photothermal technique. As before, we find that the absorption in the blue is significantly lower than had previously been generally believed

  12. Water Channel of Horseradish Peroxidase Studied by the Charge-Transfer Absorption Band of Ferric Heme

    E-print Network

    Sharp, Kim

    Water Channel of Horseradish Peroxidase Studied by the Charge-Transfer Absorption Band of Ferric The heme of horseradish peroxidase is buried in the protein, but a channel from the protein surface connects the aqueous solution to the heme site. Ferric horseradish peroxidase has an absorption band at 640

  13. Measurement of Water Vapor Concentration using Tunable Diode Laser Absorption Spectroscopy

    E-print Network

    Barrett, Alexander B.

    2010-07-14

    Tunable diode laser spectroscopy and the Beer-Lambert relation has been used to measure the absorption of water vapor both in an absorption cell and in a shock tube. The purpose of this thesis is to develop a laser diagnostic capable of determining...

  14. A practical method of determining water current velocities and diffusion coefficients in coastal waters by remote sensing techniques

    NASA Technical Reports Server (NTRS)

    James, W. P.

    1971-01-01

    A simplified procedure is presented for determining water current velocities and diffusion coefficients. Dye drops which form dye patches in the receiving water are made from an aircraft. The changes in position and size of the patches are recorded from two flights over the area. The simplified data processing procedure requires only that the ground coordinates about the dye patches be determined at the time of each flight. With an automatic recording coordinatograph for measuring coordinates and a computer for processing the data, this technique provides a practical method of determining circulation patterns and mixing characteristics of large aquatic systems. This information is useful in assessing the environmental impact of waste water discharges and for industrial plant siting.

  15. Determination of true octanol-water partition coefficients by means of solvent generated liquid-liquid chromatography

    Microsoft Academic Search

    M. Cichna; P. Markl; J. F. K. Huber

    1995-01-01

    Compared to other methods for the determination of octanol-water partition coefficients chromatography offers a number of advantages: sample purification is unnecessary, the partition coefficients of the components of a mixture can be measured simultaneously and a minimum amount of sample is needed. In the past these determinations were almost exclusively carried out by liquid-solid chromatography (LSC) on alkyl bonded silica

  16. Water vapor microwave continuum absorption: A comparison of measurements and models

    Microsoft Academic Search

    Philip W. Rosenkranz

    1998-01-01

    Measurements, made in different laboratories, of absorption by water vapor in microwave windows are compared with models for the water vapor continuum. A reanalysis of some of these measurements leads to the conclusion that the laboratory data are best represented by a combination of Liebe's (1987) millimeter-wave propagation model (MPM) for the foreign-broadened component of the water continuum and the

  17. Absorption

    NSDL National Science Digital Library

    Katherine M Knudson (Polson Middle School)

    1998-04-01

    This activity can be used to allow students to explore the concept of absorption using a variety of materials. Extensions include exploring how Native Americans used absorbtion in a number of ways. This inquiry activity was developed by a K-12 science teacher in the American Physiological SocietyÂ?s 1998 Frontiers in Physiology Program. The NSES Standards addressed by this activity are current as of the year of development. For more information on the Frontiers in Physiology Program, please visit www.frontiersinphys.org.

  18. Drinking Spring Water and Lithium Absorption: A Preliminary Study

    Microsoft Academic Search

    Ippei Shiotsuki; Takeshi Terao; Hirochika Ogami; Nobuyoshi Ishii; Reiji Yoshimura; Jun Nakamura

    Background: In Japan, there are several resorts with cold springs that have mineral water containing relatively high levels of lithium compared to tap water. Visitors to such cold-spring resorts traditionally drink 2 to 4 L of mineral water for several hours in the early morning in the belief that the water has properties which maintain physical health. The present study

  19. Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Shumate, M. S.

    1976-01-01

    Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

  20. A characteristic function to estimate the longitudinal dispersion coefficient in surface water flows over porous media

    NASA Astrophysics Data System (ADS)

    Nofuentes, M.; Polo, M. J.

    2012-04-01

    One-dimensional modelling of solute transport in shallow water flows relies on an accurate approximation of the longitudinal dispersion coefficient, E, especially under transient conditions of the water flow during the solute residence time. Previous approaches have used expressions (e.g., the Rutherford equation) that allow the inclusion of spatiotemporal variability of E during the transport process, but their accuracy is reduced in marked transient regimes since the data were obtained from experimental work in rivers. This work proposes a different approach from experimental work with slow, shallow flows over porous media in fertigation essays, and provides us with a simple, parametric sigmoid function to estimate a priori effective values of E from simple measurements of flow characteristics and variables. The results have been successfully validated and compared to the Rutherford equation approach. Furthermore, the methodology to develop this characteristic function can be easily adapted for application in other practical cases.

  1. Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes

    USGS Publications Warehouse

    Chiou, C.T.; Schmedding, D.W.; Manes, M.

    2005-01-01

    A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.

  2. Derivation of water vapour absorption cross-sections in the red region

    NASA Technical Reports Server (NTRS)

    Lal, M.; Chakrabarty, D. K.

    1994-01-01

    Absorption spectrum in 436 to 448 nm wavelength region gives NO2 and O3 column densities. This spectrum can also give H2O column density. The spectrum in the range of 655 to 667 nm contains absorption due to NO3 and H2O. Combining the absorption spectra in the wavelength ranges of 436 to 448 and 655 to 667 nm, water vapor absorption cross-sections in this range comes out to be of the order of 2.0 x 10(exp -24) cm(exp -2).

  3. Improved Algorithms for Accurate Retrieval of UV - Visible Diffuse Attenuation Coefficients in Optically Complex, Inshore Waters

    NASA Technical Reports Server (NTRS)

    Cao, Fang; Fichot, Cedric G.; Hooker, Stanford B.; Miller, William L.

    2014-01-01

    Photochemical processes driven by high-energy ultraviolet radiation (UVR) in inshore, estuarine, and coastal waters play an important role in global bio geochemical cycles and biological systems. A key to modeling photochemical processes in these optically complex waters is an accurate description of the vertical distribution of UVR in the water column which can be obtained using the diffuse attenuation coefficients of down welling irradiance (Kd()). The Sea UV Sea UVc algorithms (Fichot et al., 2008) can accurately retrieve Kd ( 320, 340, 380,412, 443 and 490 nm) in oceanic and coastal waters using multispectral remote sensing reflectances (Rrs(), Sea WiFS bands). However, SeaUVSeaUVc algorithms are currently not optimized for use in optically complex, inshore waters, where they tend to severely underestimate Kd(). Here, a new training data set of optical properties collected in optically complex, inshore waters was used to re-parameterize the published SeaUVSeaUVc algorithms, resulting in improved Kd() retrievals for turbid, estuarine waters. Although the updated SeaUVSeaUVc algorithms perform best in optically complex waters, the published SeaUVSeaUVc models still perform well in most coastal and oceanic waters. Therefore, we propose a composite set of SeaUVSeaUVc algorithms, optimized for Kd() retrieval in almost all marine systems, ranging from oceanic to inshore waters. The composite algorithm set can retrieve Kd from ocean color with good accuracy across this wide range of water types (e.g., within 13 mean relative error for Kd(340)). A validation step using three independent, in situ data sets indicates that the composite SeaUVSeaUVc can generate accurate Kd values from 320 490 nm using satellite imagery on a global scale. Taking advantage of the inherent benefits of our statistical methods, we pooled the validation data with the training set, obtaining an optimized composite model for estimating Kd() in UV wavelengths for almost all marine waters. This optimized composite set of SeaUVSeaUVc algorithms will provide the optical community with improved ability to quantify the role of solar UV radiation in photochemical and photobiological processes in the ocean.

  4. Discriminating between absorption and scattering coefficients in optical characterisation measurements on gold nanoparticle based photoacoustic contrast agents

    Microsoft Academic Search

    C. Ungureanu; A. Amelink; Henricus J. C. M. Sterenborg; S. Manohar; T. G. C. van Leeuwen; Alexander A. Oraevsky; Lihong V. Wang

    2009-01-01

    Plasmon resonant nanoparticles such as gold nanoshells and gold nanorods can be tuned to possess sharp interaction peaks in the near-infrared wavelength regions. These have great importance as contrast agents in photoacoustic imaging and as photothermal agents for therapeutic applications due to their high absorptions. While the optical properties of the particles are can be described using Mie theory and\\/or

  5. Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV

    SciTech Connect

    Higgins, P.D.; Attix, F.H.; Hubbell, J.H.; Seltzer, S.M.; Berger, M.J.

    1991-11-01

    Mass energy-transfer (Mu(sub u)/Rho) and mass energy-absorption coefficients (Mu(sub en)/Rho) are tabulated in units of (sqcm/g) for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general dosimetric interest. Cross sections for photo-effect, incoherent scattering, pair and triplet production are those compiled or generated by the National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards). Corrections are included for in-flight positron annihilation, previously not applied in NIST calculations for energies above 10 MeV.

  6. Determination of the quasi-TE mode (in-plane) graphene linear absorption coefficient via integration with silicon-on-insulator racetrack cavity resonators.

    PubMed

    Crowe, Iain F; Clark, Nicholas; Hussein, Siham; Towlson, Brian; Whittaker, Eric; Milosevic, Milan M; Gardes, Frederic Y; Mashanovich, Goran Z; Halsall, Matthew P; Vijayaraghaven, Aravind

    2014-07-28

    We examine the near-IR light-matter interaction for graphene integrated cavity ring resonators based on silicon-on-insulator (SOI) race-track waveguides. Fitting of the cavity resonances from quasi-TE mode transmission spectra reveal the real part of the effective refractive index for graphene, n(eff) = 2.23 ± 0.02 and linear absorption coefficient, ?(gTE) = 0.11 ± 0.01dB?m(-1). The evanescent nature of the guided mode coupling to graphene at resonance depends strongly on the height of the graphene above the cavity, which places limits on the cavity length for optical sensing applications. PMID:25089481

  7. A WATER VAPOR MONITOR USING DIFFERENTIAL INFRARED ABSORPTION

    EPA Science Inventory

    A water vapor monitor has been developed with adequate sensitivity and versatility for a variety of applications. Two applications for which the instrument has been designed are the continuous monitoring of water in ambient air and the measuring of the mass of water desorbed from...

  8. Influence of meal composition on canine jejunal water and electrolyte absorption.

    PubMed

    Bastidas, J A; Zinner, M J; Bastidas, J A; Orandle, M S; Yeo, C J

    1992-02-01

    The absorption of water and electrolytes from the proximal jejunal lumen increases immediately after a meal. This meal-induced jejunal absorption occurs in jejunal segments out of normal gastrointestinal continuity. This study was designed to characterize the jejunal absorptive response to a series of isovolumetric gavage-delivered stimuli. Twenty-five-centimeter canine proximal jejunal Thiry-Vella fistulas were constructed, and jejunal absorption studies (n = 66) were performed by luminal perfusion of the jejunal segments with an isotonic buffer containing 14C-labeled polyethylene glycol. Each study consisted of a 1-hour basal period, followed by a 3-hour experimental period. Nine groups were studied, each receiving one of the following isovolumetric stimuli delivered via the gavage route: water, 0.9% saline, mixed meal, protein, lipid, carbohydrate, and mannitol (150 mmol/L, 300 mmol/L, and 600 mmol/L). The water and 0.9% saline gavage groups showed no significant changes in integrated postprandial water and electrolyte absorption above basal. The isocaloric mixed meal, protein, lipid, carbohydrate, and mannitol groups all had significantly increased integrated postprandial jejunal water and electrolyte absorption above basal (P less than 0.05). These results indicate that a proabsorptive signal for meal-induced jejunal absorption originates from or distal to the stomach. Meal-induced jejunal absorption occurs in response to nutrients of diverse composition and is also responsive to nonnutritive solutes such as mannitol. These findings support a new role for gastric or intestinal chemo- or osmo-receptors in stimulating the neurohumoral mechanisms that mediate meal-induced jejunal absorption. PMID:1732119

  9. Mutual diffusion coefficients in the water-rich region of water/phenol mixtures and their relation to aggregate formation

    SciTech Connect

    Castillo, R.; Garza, C.; Orozco, J. [Instituto de Fisica (Mexico)

    1992-02-06

    Mutual diffusion coefficients in the one-phase water-rich region of the phase diagram of the phenol/water system (0-10 wt% phenol) were measured using the Taylor dispersion technique, at several temperatures and mole fractions. The values range from 0.71 to 1.88 x 10{sup -9} m{sup 2}/s. In order to obtain evidence about the formation of aggregates of pseudomicelles in this system, as it is invoked in the interpretation of bulk and surface properties, correlation lengths of the concentration fluctuations have been calculated at 328 K using the diffusion data and measured viscosities. They agree with the assumption of aggregate formation in the bulk of the solution at a phenol weight fraction about 7-8 wt%. 16 refs., 2 figs., 1 tab.

  10. Liquid water absorption and scattering effects in DOAS retrievals over oceans

    NASA Astrophysics Data System (ADS)

    Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

    2014-12-01

    Spectral effects of liquid water are present in absorption (differential optical absorption spectroscopy - DOAS) measurements above the ocean and, if insufficiently removed, may interfere with trace gas absorptions, leading to wrong results. Currently available literature cross sections of liquid water absorption are provided in coarser resolution than DOAS applications require, and vibrational Raman scattering (VRS) is mostly not considered, or is compensated for using simulated pseudo cross sections from radiative transfer modeling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS (Multi-AXis differential optical absorption spectroscopy) measurements of light penetrating very clear natural waters were performed, achieving average underwater light paths of up to 50 m. From these measurements, the retrieval of a correction spectrum (H2Ocorr) is presented, compensating simultaneously for insufficiencies in the liquid water absorption cross section and broad-banded VRS structures. Small-banded structures caused by VRS were found to be very efficiently compensated for by the intensity offset correction included in the DOAS fit. No interference between the H2Ocorr spectrum and phytoplankton absorption was found. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality, and performed better than using a liquid water cross section in combination with a simulated VRS spectrum. The decrease in the residual root mean square (rms) of the DOAS fit depends on the measurement's contamination with liquid water structures, and ranges from ? 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ocorr spectrum was found to prevent misfits of NO2 slant columns, especially for very low NO2 scenarios, and thus increases the reliability of the fit. In test fits on OMI satellite data, the H2Ocorr spectrum was found selectively above ocean surfaces, where it decreases the rms by up to ? 11 %.

  11. Effect of water content on strontium retardation factor and distribution coefficient in Chinese loess.

    PubMed

    Huo, Lijuan; Qian, Tianwei; Hao, Junting; Liu, Hongfang; Zhao, Dongye

    2013-12-01

    Geological burial and landfill are often employed for disposal of nuclear wastes. Typically, radionuclides from nuclear facilities transport through the unsaturated zone before reaching the groundwater aquifer. However, transport studies are often conducted under saturated and steady-state flow conditions. This research aimed to examine the effects of unsaturated flow conditions and soil water content (?) on Sr sorption and retardation in Chinese loess through 1D column transport experiments. Reagent SrCl2 was used as a surrogate for the radioactive isotope ((90)Sr) in the experiment because of their analogous adsorption and transportation characteristics. The spatial distribution of Sr along the column length was determined by segmenting the soil bed and analysing the Sr content in each soil segment following each column breakthrough test. The single-region (SR) and two-region (TR) models were employed to interpret the transport data of Sr as well as a tracer (Br(-)), which resulted in the dispersion coefficient (D) and retardation factor (Rd) under a given set of unsaturated flow conditions. For the tracer, the SR and TR models offered nearly the same goodness of fitting to the breakthrough curves (R(2) ? 0.97 for both models). For the highly sorptive Sr, however, the TR model provided better fitting (R(2), 0.80-0.96) to the Sr retention profiles than the SR model (R(2), 0.20-0.89). The Sr retention curves exhibited physical non-equilibrium characteristics, particularly at lower water content of the soil. For the unsaturated soil, D and the pore water velocity (v) displayed a weak linear correlation, which is attributed to the altering dispersivity as the water content varies. A much improved linear correlation was observed between D and v/?. The retardation factor of Sr increased from 69.1 to 174.2 as ? decreased from 0.46 to 0.26 (cm(3) cm(-3)), while the distribution coefficient (Kd) based on Rd remained nearly unchanged at various ? levels. These results illustrated that water content must be taken into account in determining radionuclide Rd values in Chinese loess, while Kd values can be derived from the unsaturated column experiments and can be considered constant at various levels of ?. PMID:24047556

  12. Donor impurity-related linear and nonlinear intraband optical absorption coefficients in quantum ring: effects of applied electric field and hydrostatic pressure

    PubMed Central

    2012-01-01

    The linear and nonlinear intraband optical absorption coefficients in GaAs three-dimensional single quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and electric field, applied along the growth direction of the heterostructure, the energies of the ground and first excited states of a donor impurity have been found using the effective mass approximation and a variational method. The energies of these states are examined as functions of the dimensions of the structure, electric field, and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as a function of incident photon energy for several configurations of the system. It is found that the variation of distinct sizes of the structure leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical spectrum. In addition, we have found that the application of an electric field leads to a redshift, whereas the influence of hydrostatic pressure leads to a blueshift (in the case of on-ring-center donor impurity position) of the resonant peaks of the intraband optical spectrum. PMID:23021497

  13. Interrelation between the crystallinity of polysaccharides and water absorption

    NASA Astrophysics Data System (ADS)

    Prusov, A. N.; Prusova, S. M.; Radugin, M. V.; Zakharov, A. G.

    2014-05-01

    The maximum sorption of water and its vapors is calculated using experimental data from calorimetric and effusion studies of flax, wood, and cotton cellulose. X-day diffraction is used to determine the crystallinity of cellulose samples. The equations relating crystallinity ( X) with maximum sorption and the enthalpy of interaction between cellulose and water are presented. Experimental results and the literature data on water sorption by chitin, chitosan and other polysaccharides show that our equations for calculating crystallinity are correct.

  14. Mass accommodation coefficient of water: A combined computational fluid dynamics and experimental data analysis

    NASA Astrophysics Data System (ADS)

    VoigtläNder, J.; Stratmann, F.; Niedermeier, D.; Wex, H.; Kiselev, A.

    2007-10-01

    The mass accommodation coefficient ?mass of water vapor in NaCl solutions has been studied for realistic lower atmospheric conditions. To determine ?mass, a combination of experimental data and computational fluid dynamics (CFD) modeling has been applied. Experiments were performed at the Leipzig Aerosol Cloud Interaction Simulator (LACIS), a laminar flow diffusion tube for measurements of both hygroscopic growth and cloud condensation nuclei (CCN) activation. Quasi-monodisperse sodium chloride particles with 54 nm and 108 nm in diameter have been used as condensation nuclei. To characterize particle growth, mean droplet diameters have been measured at the outlet of LACIS with a white-light optical particle spectrometer. Measurements were performed for different saturation ratios in the range between 1.0 and 1.02. Experiments have been modeled using the Computational Fluid Dynamics Code (CFD-Code) FLUENT6 combined with the Fine Particle Model (FPM). For determination of ?mass, measured droplet diameters have been compared with calculated ones. The accommodation coefficient in the theoretical calculations was varied to achieve a quantitative comparison with the measurements. Experimental data shown in this study are consistent with ?mass > 0.30. Therefore our results support previous studies applying different experimental techniques.

  15. An NMR microscopy study of water absorption in cork

    Microsoft Academic Search

    A. M. Gil; M. H. Lopes; C. Pascoal Neto; P. T. Callaghan

    2000-01-01

    NMR Microscopy is used to measure the imbibition of water into natural cork, extractives-free cork and desuberised cork. The results clearly indicate that suberin is the key constituent which determines the ability of cork to resist water uptake. Furthermore, a particular suberin with distinct spectral properties as viewed by 13C NMR is shown to be the component responsible for cork

  16. Dynamics of Water Absorption and Evaporation During Methanol Droplet Combustion in Microgravity

    NASA Technical Reports Server (NTRS)

    Hicks, Michael C.; Dietrich, Daniel L.; Nayagam, Vedha; Williams, Forman A.

    2012-01-01

    The combustion of methanol droplets is profoundly influenced by the absorption and evaporation of water, generated in the gas phase as a part of the combustion products. Initially there is a water-absorption period of combustion during which the latent heat of condensation of water vapor, released into the droplet, enhances its burning rate, whereas later there is a water-evaporation period, during which the water vapor reduces the flame temperature suffciently to extinguish the flame. Recent methanol droplet-combustion experiments in ambient environments diluted with carbon dioxide, conducted in the Combustion Integrated Rack on the International Space Station (ISS), as a part of the FLEX project, provided a method to delineate the water-absorption period from the water-evaporation period using video images of flame intensity. These were obtained using an ultra-violet camera that captures the OH* radical emission at 310 nm wavelength and a color camera that captures visible flame emission. These results are compared with results of ground-based tests in the Zero Gravity Facility at the NASA Glenn Research Center which employed smaller droplets in argon-diluted environments. A simplified theoretical model developed earlier correlates the transition time at which water absorption ends and evaporation starts. The model results are shown to agree reasonably well with experiment.

  17. Small effect of water on upper mantle rheology based on silicon self-diffusion coefficients

    NASA Astrophysics Data System (ADS)

    Fei, H.; Wiedenbeck, M.; Yamazaki, D.; Katsura, T.

    2012-12-01

    Water has been considered to significantly affect the mantle dynamics. In particular, experimental deformation studies [1-4] claimed that even small amount of water enhanced the creep in olivine by orders of magnitude. However, we note that their results are experimental artifact due to a number of limitations: e.g., unavoidable grain boundary sliding when polycrystalline samples were used; limited ranges of water contents due to the limited pressures; several orders higher stress and strain rate than those in nature. High temperature creep of silicate minerals is controlled by silicon self-diffusion. Therefore, measurement of silicon self-diffusion coefficients (DSi) in minerals, which can be performed without these limitations, is an independent way to study the mantle rheology. In this study, we measured DSi in Mg end-member of olivine, namely, forsterite, as a function of water content (CH2O) across a wide range, and concluded that effect of water on upper mantle rheology is very small. Forsterite single crystals were doped with <1 to ~800 ?g/g of water at 1600 K, 8 GPa using talc+brucite water sources and graphite buffer. The CH2O in the samples were controlled by the ratio of water sources to graphite. The water doped samples were polished, deposited with 500 nm 29Si enriched Mg2SiO4 thin films, and annealed at 8 GPa, 1600 or 1800 K for diffusion with the same proportion of water sources, which successfully made constant values of CH2O during diffusion annealing. The diffusion profiles were obtained by SIMS. CH2O in the samples were determined by FT-IR before and after diffusion, and also examined by SIMS. Our results yield a relationship: DSi ? (CH2O)1/3. This is explained by defect chemistry, where DSi?[VSi????]×[VO??]?(CH2O)2/3×(CH2O)-1/3=(CH2O)1/3 under the charge neutrality condition of [(OH)O?]=2[VMg??] because both Si and O vacancies are needed for Si ions to diffuse. The water contents exponent (1/3) determined in this study is much smaller than 1.2 [5], which was estimated based on deformation experiments. The small water content exponent demonstrates that effect of water on upper mantle rheology is very small in comparing with other factors like temperature, or shear stress. The difference in viscosity of olivine between dry (e.g., ~1 ?g/g of water) and 1000 ?g/g (maximum in upper mantle [6]) is only by a factor of 10. The softening of oceanic lithosphere, which is required to explain the plate motion, cannot be caused by hydration. [1] Karato et al. (1986), JGR 91, 8151-8176. [2] Mei and Kohlstedt (2000a), JGR 105(B9), 21471-21481. [3] Mei and Kohlstedt (2000b), JGR 105(B9), 21457-21469. [4] Jung and Karato (2001), Science 293, 1460-1463. [5] Hirth and Kohlstedt (2003), Geophys. Monogr. Am. Geophys. Union. 138, 83-106. [6] Hirschmann (2006), An. Rev. Earth Planet. Sci. 34, 629-653.

  18. Methods for analysis of selected metals in water by atomic absorption

    USGS Publications Warehouse

    Fishman, Marvin J.; Downs, Sanford C.

    1966-01-01

    This manual describes atomic-absorption-spectroscopy methods for determining calcium, copper, lithium, magnesium, manganese, potassium, sodium, strontium and zinc in atmospheric precipitation, fresh waters, and brines. The procedures are intended to be used by water quality laboratories of the Water Resources Division of the U.S. Geological Survey. Detailed procedures, calculations, and methods for the preparation of reagents are given for each element along with data on accuracy, precision, and sensitivity. Other topics discussed briefly are the principle of atomic absorption, instrumentation used, and special analytical techniques.

  19. Investigation of a Flow Coefficient for Predicting a Natural Circulation of Water in a Built-in-storage Solar Water Heater

    Microsoft Academic Search

    Pachern Jans; Supachart Chungpaibulpatana; Bundit Limmeechokchai

    This paper describes an investigation of an overall flow coefficient Kf for predicting thermosyphon flow rate of water circulating in a built-in-storage (BIS) solar water heater. Firstly, a set of mathematical equations for solving storage tank temperatures of the BIS solar water heater has been developed based on the energy balances on three main components: absorber plate, collector channel and

  20. Characterization of thin poly(dimethylsiloxane)-based tissue-simulating phantoms with tunable reduced scattering and absorption coefficients at visible and near-infrared wavelengths.

    PubMed

    Greening, Gage J; Istfan, Raeef; Higgins, Laura M; Balachandran, Kartik; Roblyer, Darren; Pierce, Mark C; Muldoon, Timothy J

    2014-01-01

    Optical phantoms are used in the development of various imaging systems. For certain applications, the development of thin phantoms that simulate the physical size and optical properties of tissue is important. Here, we demonstrate a method for producing thin phantom layers with tunable optical properties using poly(dimethylsiloxane) (PDMS) as a substrate material. The thickness of each layer (between 115 and 880 ?m) was controlled using a spin coater. The reduced scattering and absorption coefficients were controlled using titanium dioxide and alcohol-soluble nigrosin, respectively. These optical coefficients were quantified at six discrete wavelengths (591, 631, 659, 691, 731, and 851 nm) at varying concentrations of titanium dioxide and nigrosin using spatial frequency domain imaging. From the presented data, we provide lookup tables to determine the appropriate concentrations of scattering and absorbing agents to be used in the design of PDMS-based phantoms with specific optical coefficients. In addition, heterogeneous phantoms mimicking the layered features of certain tissue types may be fabricated from multiple stacked layers, each with custom optical properties. These thin, tunable PDMS optical phantoms can simulate many tissue types and have broad imaging calibration applications in endoscopy, diffuse optical spectroscopic imaging, and optical coherence tomography, etc. PMID:25387084

  1. Characterization of thin poly(dimethylsiloxane)-based tissue-simulating phantoms with tunable reduced scattering and absorption coefficients at visible and near-infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Greening, Gage J.; Istfan, Raeef; Higgins, Laura M.; Balachandran, Kartik; Roblyer, Darren; Pierce, Mark C.; Muldoon, Timothy J.

    2014-11-01

    Optical phantoms are used in the development of various imaging systems. For certain applications, the development of thin phantoms that simulate the physical size and optical properties of tissue is important. Here, we demonstrate a method for producing thin phantom layers with tunable optical properties using poly(dimethylsiloxane) (PDMS) as a substrate material. The thickness of each layer (between 115 and 880 ?m) was controlled using a spin coater. The reduced scattering and absorption coefficients were controlled using titanium dioxide and alcohol-soluble nigrosin, respectively. These optical coefficients were quantified at six discrete wavelengths (591, 631, 659, 691, 731, and 851 nm) at varying concentrations of titanium dioxide and nigrosin using spatial frequency domain imaging. From the presented data, we provide lookup tables to determine the appropriate concentrations of scattering and absorbing agents to be used in the design of PDMS-based phantoms with specific optical coefficients. In addition, heterogeneous phantoms mimicking the layered features of certain tissue types may be fabricated from multiple stacked layers, each with custom optical properties. These thin, tunable PDMS optical phantoms can simulate many tissue types and have broad imaging calibration applications in endoscopy, diffuse optical spectroscopic imaging, and optical coherence tomography, etc.

  2. Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune

    E-print Network

    Fraine, Jonathan; Benneke, Björn; Knutson, Heather; Jordán, Andrés; Espinoza, Néstor; Madhusudhan, Nikku; Wilkins, Ashlee; Todorov, Kamen

    2014-01-01

    Transmission spectroscopy to date has detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain high mean molecular weights, opaque clouds, or scattering hazes in their atmospheres, obscuring our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of HAT-P-11b (~4 Earth radii) from the optical to the infrared. We detected water vapour absorption at 1.4 micrometre wavelength. The amplitude of the water absorption (approximately 250 parts-per- million) indicates that the planetary atmosphere is predominantly clear down to ~1 mbar, and sufficiently hydrogen-rich to exhibit a large scale height. The spectrum is indicative of a planetary atmosphere with an upper limit of ~700 times the abundance of...

  3. Physicochemical properties of macrogol ointment and emulsion ointment blend developed for regulation of water absorption.

    PubMed

    Noda, Yasuhiro; Watanabe, Kazuya; Sanagawa, Akimasa; Sobajima, Yu; Fujii, Satoshi

    2011-10-31

    Pressure ulcers can form with excess pressure and shearing stress on skin tissue. Because pressure ulcer is often accompanies by exudates, selection of appropriate topical emulsion ointment is difficult. Blended ointments consisting of emulsion base and water-soluble base are clinically used for adjustment of wound moist environment. Because regulating the amount of wound exudates can enhance treatment efficacy, two new blended ointments were developed. LY-SL blended ointment consisted of lysozyme hydrochloride water-in-oil (w/o) emulsion (LY-cream) and sulfadiazine macrogol (polyethylene glycol) ointment (SL-pasta). TR-SL blended ointment consisted of tretinoin tocoferil oil-in-water (o/w) emulsion (TR-cream) and SL-pasta (TR-SL). LY-SL and TR-SL were applied to Franz diffusion cell with cellulose membranes for the evaluation of water absorption characteristics at 32 °C. Water absorption rate constants (mg/cm(2)/min(0.5)) were 12.5, 16.3 and 34.6 for LY-cream, TR-cream and SL-pasta, respectively. Water absorption rate constants for LY-SL and TR-SL (SL-pasta 70%) exhibited intermediate values of 21.2 and 27.2, as compared to each ointment alone, respectively. Because amount of water absorbed was linearly related to square root of time, it was suggested that water-absorbable macrogol was surrounded by oily ingredients forming matrix structure. This diffusion-limited structure may regulate water absorption capacity. This is the first report of physicochemical properties of macrogol ointment and emulsion ointment blend developed for regulation of water absorption. The blended ointment can properly regulate amount of exudates in wounds and may be useful for treatment of pressure ulcers. PMID:21820500

  4. Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements.

    PubMed

    Ptashnik, Igor V; McPheat, Robert A; Shine, Keith P; Smith, Kevin M; Williams, R Gary

    2012-06-13

    For a long time, it has been believed that atmospheric absorption of radiation within wavelength regions of relatively high infrared transmittance (so-called 'windows') was dominated by the water vapour self-continuum, that is, spectrally smooth absorption caused by H(2)O--H(2)O pair interaction. Absorption due to the foreign continuum (i.e. caused mostly by H(2)O--N(2) bimolecular absorption in the Earth's atmosphere) was considered to be negligible in the windows. We report new retrievals of the water vapour foreign continuum from high-resolution laboratory measurements at temperatures between 350 and 430?K in four near-infrared windows between 1.1 and 5??m (9000-2000?cm(-1)). Our results indicate that the foreign continuum in these windows has a very weak temperature dependence and is typically between one and two orders of magnitude stronger than that given in representations of the continuum currently used in many climate and weather prediction models. This indicates that absorption owing to the foreign continuum may be comparable to the self-continuum under atmospheric conditions in the investigated windows. The calculated global-average clear-sky atmospheric absorption of solar radiation is increased by approximately 0.46?W?m(-2) (or 0.6% of the total clear-sky absorption) by using these new measurements when compared with calculations applying the widely used MTCKD (Mlawer-Tobin-Clough-Kneizys-Davies) foreign-continuum model. PMID:22547232

  5. The distribution coefficients of phenol and substituted phenols in the ammonium sulfate-poly-N-vinylpyrrolidone-water system

    NASA Astrophysics Data System (ADS)

    Churilina, E. V.; Sukhanov, P. T.; Korenman, Ya. I.; Il'in, A. N.; Shatalov, G. V.; Bolotov, V. M.

    2011-04-01

    The extraction of phenols from water-salt solutions was performed using a water-soluble polymer (poly-N-vinylpyrrolidone). The distribution coefficients, the degree of extraction of 13 phenols, and interrelation between the extraction characteristics and structure of distributed compounds were determined. The conditions of the process were optimized to provide maximum extraction of phenols by poly-N-vinylpyrrolidone from water-salt solutions.

  6. Low-Dimensional Water on Ru(0001)Model System for X-ray Absorption Spectroscopy Studies of Liquid Water

    SciTech Connect

    Nordlund, D

    2012-02-14

    We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

  7. Low-Dimensional Water on Ru(0001); Model System for X-ray Absorption Spectroscopy Studies of Liquid Water

    SciTech Connect

    Nordlund, D.; Ogasawara, H.; Andersson, K.J.; Tatarkhanov, M.; Salmeron, M.; Pettersson, L. G. M.; Nilsson, A.

    2009-05-11

    We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

  8. Isotopic mass-dependence of metal cation diffusion coefficients in liquid water

    SciTech Connect

    Bourg, I.C.; Richter, F.M.; Christensen, J.N.; Sposito, G.

    2009-01-11

    Isotope distributions in natural systems can be highly sensitive to the mass (m) dependence of solute diffusion coefficients (D) in liquid water. Isotope geochemistry studies routinely have assumed that this mass dependence either is negligible (as predicted by hydrodynamic theories) or follows a kinetic-theory-like inverse square root relationship (D {proportional_to} m{sup -0.5}). However, our recent experimental results and molecular dynamics (MD) simulations showed that the mass dependence of D is intermediate between hydrodynamic and kinetic theory predictions (D {proportional_to} m{sup -{beta}} with 0 {<=} {beta} < 0.2 for Li{sup +}, Cl{sup -}, Mg{sup 2+}, and the noble gases). In this paper, we present new MD simulations and experimental results for Na{sup +}, K{sup +}, Cs{sup +}, and Ca{sup 2+} that confirm the generality of the inverse power-law relation D {proportional_to} m{sup -{beta}}. Our new findings allow us to develop a general description of the influence of solute valence and radius on the mass dependence of D for monatomic solutes in liquid water. This mass dependence decreases with solute radius and with the magnitude of solute valence. Molecular-scale analysis of our MD simulation results reveals that these trends derive from the exponent {beta} being smallest for those solutes whose motions are most strongly coupled to solvent hydrodynamic modes.

  9. Characteristics of nutrient absorption and water purification in some plant species grown by floating culture system

    Microsoft Academic Search

    Akira Miyazaki; Teruo Takeuchi; Hitomi Nakamura; Yoshinori Yamamoto; Fumitake Kubota

    2004-01-01

    Nutrient absorption and water purification by rice (Oryza sativa L.), canna (Canna indica L.), reed (Phragmites communis Trin.), and umbrella plant (Cyperus alternifolius L.), grown by the floating culture system, were compared under different pH conditions in natural water. The pH of the rooting zone in natural water changed due to the increase in the CO2 concentration associated with root

  10. Impact of MIE-Resonances on the Atmospheric Absorption of Water Clouds

    NASA Technical Reports Server (NTRS)

    Wiscombe, W.; Kinne, S.; Nussenzveig, H.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Clouds strongly modulate radiative transfer processes in the Earth's atmosphere. Studies, which simulate bulk properties of clouds, such as absorption, require methods that accurately account for multiple scattering among individual cloud particles. Multiple scattering processes are well described by MIE-theory, if interacting particles have a spherical shape. This is a good assumption for water droplets. Thus, simulations for water clouds (especially for interactions with solar radiation) usually apply readily available MIE-codes. The presence of different drop-sizes, however, necessitates repetitive calculations for many sizes. The usual representation by a few sizes is likely to miss contributions from densely distributed, sharp resonances. Despite their usually narrow width, integrated over the entire size-spectrum of a cloud droplet distribution, the impact of missed resonances could add up. The consideration of these resonances tends to increase cloud extinction and cloud absorption. This mechanism for a larger (than by MIE-methods predicted) solar absorption has the potential to explain observational evidence of larger than predicted cloud absorption at solar wavelengths. The presentation will address the absorption impact of added resonances for typical properties of water clouds (e.g. drop size distributions, drop concentrations and cloud geometry). Special attention will be given to scenarios with observational evidence of law than simulated solar absorption; particularly if simultaneous measurements of cloud micro- and macrophysical properties are available.

  11. Nonlinear absorption of femtosecond laser pulses (800 nm) by atmospheric air and water vapour

    SciTech Connect

    Kiselev, A M; Ponomarev, Yu N; Stepanov, A N; Tikhomirov, A B; Tikhomirov, B A

    2011-11-30

    Quantitative data on the nonlinear absorption cross sections of femtosecond Ti : Sapphire laser pulses in air and water vapour have been obtained. A photoacoustic spectrometer calibrated based on the calculated value of linear absorption of laser pulses with a wavelength of 800 nm and a spectral width of 17.7 nm is used to find the nonlinear absorption cross sections of water vapour and air: {sigma}{sub 2}{sup w} = (2.6{+-}0.4) Multiplication-Sign 10{sup -55} cm{sup 4} s and {sigma}{sub 2}{sup a} = (8.7{+-}1.0) Multiplication-Sign 10{sup -56} cm{sup 4} s, respectively. Based on measuring the absorption of femtosecond Ti : Sapphire laser pulses with a photoacoustic detector calibrated with the known linear absorption of ruby laser radiation by water vapour in air, the air nonlinear absorption cross section is found to be (8.2{+-}0.9) Multiplication-Sign 10{sup -56} cm{sup 4} s.

  12. Magnesium absorption from mineral water decreases with increasing quantities of magnesium per serving in rats.

    PubMed

    Nakamura, Eri; Tai, Hideyuki; Uozumi, Yoshinobu; Nakagawa, Koji; Matsui, Tohru

    2012-01-01

    It is hypothesized that magnesium (Mg) absorption from mineral water is affected by the concentration of Mg in the water, the consumption pattern, and the volume consumed per serving. The present study examined the effect of serving volume and consumption pattern of artificial mineral water (AMW) and Mg concentration on Mg absorption in rats. Magnesium in AMW was labeled with magnesium-25 as a tracer. Each group consisted of 6 or 7 rats. In experiment 1, the rats received 1 mL of AMW containing 200 mg Mg/L at 4 times, 400 mg Mg/L twice, or 800 mg Mg/L at 1 time. In experiment 2, the rats received 1 mL of AMW containing 200 mg Mg/L or 0.25 mL of AMW containing 800 mg Mg/L at 4 times or 1 mL of AMW containing 800 mg Mg/L at 1 time. The absorption of Mg decreased with increasing Mg concentrations in the same serving volume of AMW with different serving frequencies. When the AMW containing 800 mg Mg/L was portioned into 4 servings, Mg absorption increased to the level of absorption in the group exposed to AMW containing 200 mg Mg/L served at the same frequency. These results suggest that the Mg concentration and the volume of AMW do not affect Mg absorption per se, but Mg absorption from AMW decreases when the amount of Mg in each serving is increased. Thus, frequent consumption is preferable for mineral water rich in Mg when the total consumption of mineral water is the same. PMID:22260865

  13. An Accurate Method for Computing the Absorption of Solar Radiation by Water Vapor

    NASA Technical Reports Server (NTRS)

    Chou, M. D.

    1980-01-01

    The method is based upon molecular line parameters and makes use of a far wing scaling approximation and k distribution approach previously applied to the computation of the infrared cooling rate due to water vapor. Taking into account the wave number dependence of the incident solar flux, the solar heating rate is computed for the entire water vapor spectrum and for individual absorption bands. The accuracy of the method is tested against line by line calculations. The method introduces a maximum error of 0.06 C/day. The method has the additional advantage over previous methods in that it can be applied to any portion of the spectral region containing the water vapor bands. The integrated absorptances and line intensities computed from the molecular line parameters were compared with laboratory measurements. The comparison reveals that, among the three different sources, absorptance is the largest for the laboratory measurements.

  14. Towards the reanalysis of void coefficients measurements at proteus for high conversion light water reactor lattices

    SciTech Connect

    Hursin, M.; Koeberl, O.; Perret, G. [Paul Scherrer Institut PSI, 5232 Villigen (Switzerland)

    2012-07-01

    High Conversion Light Water Reactors (HCLWR) allows a better usage of fuel resources thanks to a higher breeding ratio than standard LWR. Their uses together with the current fleet of LWR constitute a fuel cycle thoroughly studied in Japan and the US today. However, one of the issues related to HCLWR is their void reactivity coefficient (VRC), which can be positive. Accurate predictions of void reactivity coefficient in HCLWR conditions and their comparisons with representative experiments are therefore required. In this paper an inter comparison of modern codes and cross-section libraries is performed for a former Benchmark on Void Reactivity Effect in PWRs conducted by the OECD/NEA. It shows an overview of the k-inf values and their associated VRC obtained for infinite lattice calculations with UO{sub 2} and highly enriched MOX fuel cells. The codes MCNPX2.5, TRIPOLI4.4 and CASMO-5 in conjunction with the libraries ENDF/B-VI.8, -VII.0, JEF-2.2 and JEFF-3.1 are used. A non-negligible spread of results for voided conditions is found for the high content MOX fuel. The spread of eigenvalues for the moderated and voided UO{sub 2} fuel are about 200 pcm and 700 pcm, respectively. The standard deviation for the VRCs for the UO{sub 2} fuel is about 0.7% while the one for the MOX fuel is about 13%. This work shows that an appropriate treatment of the unresolved resonance energy range is an important issue for the accurate determination of the void reactivity effect for HCLWR. A comparison to experimental results is needed to resolve the presented discrepancies. (authors)

  15. Evaluation of moisture-related attenuation coefficient and water diffusion velocity in human skin using optical coherence tomography.

    PubMed

    Lee, Cheng-Kuang; Tsai, Meng-Tsan; Chang, Feng-Yu; Yang, Chih-Hsun; Shen, Su-Chin; Yuan, Ouyang; Yang, Chih-He

    2013-01-01

    In this study, time-resolved optical coherence tomography (OCT) scanning images of the process of water diffusion in the skin that illustrate the enhancement in the backscattered intensities due to the increased water concentration are presented. In our experiments, the water concentration in the skin was increased by soaking the hand in water, and the same region of the skin was scanned and measured with the OCT system and a commercial moisture monitor every three minutes. To quantitatively analyze the moisture-related optical properties and the velocity of water diffusion in human skin, the attenuation coefficients of the skin, including the epidermis and dermis layers, were evaluated. Furthermore, the evaluated attenuation coefficients were compared with the measurements made using the commercial moisture monitor. The results demonstrate that the attenuation coefficient increases as the water concentration increases. Furthermore, by evaluating the positions of center-of mass of the backscattered intensities from OCT images, the diffusion velocity can be estimated. In contrast to the commercial moisture monitor, OCT can provide three-dimensional structural images of the skin and characterize its optical property, which together can be used to observe morphological changes and quantitatively evaluate the moisture-related attenuation coefficients in different skin layers. PMID:23529149

  16. [Study of high temperature water vapor concentration measurement method based on absorption spectroscopy].

    PubMed

    Chen, Jiu-ying; Liu, Jian-guo; He, Jun-feng; He, Ya-bai; Zhang, Guang-le; Xu, Zhen-yu; Gang, Qiang; Wang, Liao; Yao, Lu; Yuan, Song; Ruan, Jun; Dai, Yun-hai; Kan, Rui-feng

    2014-12-01

    Tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion temperature, gas component concentration, velocity and other flow parameters, owing to its high sensitivity, fast time response, non-invasive character and robust nature. In order to obtain accurate water vapor concentration at high temperature, several absorption spectra of water vapor near 1.39 ?m from 773 to 1273 K under ordinary pressure were recorded in a high temperature experiment setup using a narrow band diode laser. The absorbance of high temperature absorption spectra was calculated by combined multi-line nonlinear least squares fitting method. Two water vapor absorption lines near 7154.35 and 7157.73 cm(-1) were selected for measurement of water vapor at high temperature. A model method for high temperature water vapor concentration was first proposed. Water vapor concentration from the model method at high temperature is in accordance with theoretical reasoning, concentration measurement standard error is less than 0.2%, and the relative error is less than 6%. The feasibility of this measuring method is verified by experiment. PMID:25881402

  17. Peculiar absorption of water by hydrophobized glass beads

    Microsoft Academic Search

    Laurent Forny; Isabelle Pezron; Kashayar Saleh; Pierre Guigon; Ljepsa Komunjer

    2005-01-01

    Hydrophobization of industrial powders is frequently used to avoid caking during transport and storage. Caking is induced by the formation of liquid bridges through capillary condensation at the contact point between particles. Liquid–solid contact angles are commonly determined through macroscopic experiments but the relationship between such observations and local water interaction with the microparticle is not straightforward. Here, model powders

  18. ABSORPTION OF LEAD FROM DRINKING WATER WITH VARYING MINERAL CONTENT

    EPA Science Inventory

    Lead (Pb) (200 ppm) was administered via drinking water to rats for nine weeks. In addition, the rats were grouped so that they received 75, 100, 150 and 250% of the minimum daily requirements (MDR) of calcium (Ca), iron (Fe), and magnesium (Mg) as required for normal growth. The...

  19. Water Absorption and Mechanical Properties of Silica Porous Glasses

    Microsoft Academic Search

    Ya. O. Roizin; S. A. Gevelyuk; L. P. Prokopovich; D. P. Savin; E. Rysiakiewicz-Pasek; K. Marczuk

    1997-01-01

    We have estimated the mechanical properties of silica porous glasses (SPG) using special two-layered structures consisting of a SPG layer on a solid glass substrate. These structures turned curved after keeping them in moist atmosphere. The linear dimensions of dry free-standing SPG wafers with the same pore size distribution increased significantly (up to 1.5%) after water vapour soaking. Bending angles

  20. Ab initio calculation of the electronic absorption spectrum of liquid water

    SciTech Connect

    Martiniano, Hugo F. M. C.; Galamba, Nuno [Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal)] [Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal); Cabral, Benedito J. Costa, E-mail: ben@cii.fc.ul.pt [Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal) [Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal); Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto de Física da Universidade de São Paulo, CP 66318, 05314-970 São Paulo, SP (Brazil)

    2014-04-28

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  1. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  2. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system.

    PubMed

    Ponsardin, P; Higdon, N S; Grossmann, B E; Browell, E V

    1994-09-20

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two étalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-étalon laser system. High spectral purity (> 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by usingthis laser, which has a finite linewidth of 0.02 cm(-1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(-1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity étalons is presented, and a closed-loop computer control for active stabilization of the two intracavity étalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (? 1.5 h) of less than 0.7 pm in the laboratory. PMID:20941182

  3. Assessment of PDMS-water partition coefficients: implications for passive environmental sampling of hydrophobic organic compounds.

    PubMed

    DiFilippo, Erica L; Eganhouse, Robert P

    2010-09-15

    Solid-phase microextraction (SPME) has shown potential as an in situ passive-sampling technique in aquatic environments. The reliability of this method depends upon accurate determination of the partition coefficient between the fiber coating and water (K(f)). For some hydrophobic organic compounds (HOCs), K(f) values spanning 4 orders of magnitude have been reported for polydimethylsiloxane (PDMS) and water. However, 24% of the published data examined in this review did not pass the criterion for negligible depletion, resulting in questionable K(f) values. The range in reported K(f) is reduced to just over 2 orders of magnitude for some polychlorinated biphenyls (PCBs) when these questionable values are removed. Other factors that could account for the range in reported K(f), such as fiber-coating thickness and fiber manufacturer, were evaluated and found to be insignificant. In addition to accurate measurement of K(f), an understanding of the impact of environmental variables, such as temperature and ionic strength, on partitioning is essential for application of laboratory-measured K(f) values to field samples. To date, few studies have measured K(f) for HOCs at conditions other than at 20° or 25 °C in distilled water. The available data indicate measurable variations in K(f) at different temperatures and different ionic strengths. Therefore, if the appropriate environmental variables are not taken into account, significant error will be introduced into calculated aqueous concentrations using this passive sampling technique. A multiparameter linear solvation energy relationship (LSER) was developed to estimate log K(f) in distilled water at 25 °C based on published physicochemical parameters. This method provided a good correlation (R(2) = 0.94) between measured and predicted log K(f) values for several compound classes. Thus, an LSER approach may offer a reliable means of predicting log K(f) for HOCs whose experimental log K(f) values are presently unavailable. Future research should focus on understanding the impact of environmental variables on K(f). Obtaining the data needed for an LSER approach to estimate K(f) for all environmentally relevant HOCs would be beneficial to the application of SPME as a passive-sampling technique. PMID:20726511

  4. Assessment of PDMS-water partition coefficients: implications for passive environmental sampling of hydrophobic organic compounds

    USGS Publications Warehouse

    DiFilippo, Erica L.; Eganhouse, Robert P.

    2010-01-01

    Solid-phase microextraction (SPME) has shown potential as an in situ passive-sampling technique in aquatic environments. The reliability of this method depends upon accurate determination of the partition coefficient between the fiber coating and water (Kf). For some hydrophobic organic compounds (HOCs), Kf values spanning 4 orders of magnitude have been reported for polydimethylsiloxane (PDMS) and water. However, 24% of the published data examined in this review did not pass the criterion for negligible depletion, resulting in questionable Kf values. The range in reported Kf is reduced to just over 2 orders of magnitude for some polychlorinated biphenyls (PCBs) when these questionable values are removed. Other factors that could account for the range in reported Kf, such as fiber-coating thickness and fiber manufacturer, were evaluated and found to be insignificant. In addition to accurate measurement of Kf, an understanding of the impact of environmental variables, such as temperature and ionic strength, on partitioning is essential for application of laboratory-measured Kf values to field samples. To date, few studies have measured Kf for HOCs at conditions other than at 20 degrees or 25 degrees C in distilled water. The available data indicate measurable variations in Kf at different temperatures and different ionic strengths. Therefore, if the appropriate environmental variables are not taken into account, significant error will be introduced into calculated aqueous concentrations using this passive sampling technique. A multiparameter linear solvation energy relationship (LSER) was developed to estimate log Kf in distilled water at 25 degrees C based on published physicochemical parameters. This method provided a good correlation (R2 = 0.94) between measured and predicted log Kf values for several compound classes. Thus, an LSER approach may offer a reliable means of predicting log Kf for HOCs whose experimental log Kf values are presently unavailable. Future research should focus on understanding the impact of environmental variables on Kf. Obtaining the data needed for an LSER approach to estimate Kf for all environmentally relevant HOCs would be beneficial to the application of SPME as a passive-sampling technique.

  5. State-of-the-Art Review on Crystallization Control Technologies for water/LiBr Absorption Heat Pumps

    SciTech Connect

    Wang, Kai [ORNL; Abdelaziz, Omar [ORNL; Kisari, Padmaja [ORNL; Vineyard, Edward Allan [ORNL

    2011-01-01

    The key technical barrier to using water/lithium bromide (LiBr) as the working fluid in aircooled absorption chillers and absorption heat-pump systems is the risk of crystallization when the absorber temperature rises at fixed evaporating pressure. This article reviews various crystallization control technologies available to resolve this problem: chemical inhibitors, heat and mass transfer enhancement methods, thermodynamic cycle modifications, and absorption system-control strategies. Other approaches, such as boosting absorber pressure and J-tube technology, are reviewed as well. This review can help guide future efforts to develop water/LiBr air-cooled absorption chillers and absorption heatpump systems.

  6. Effects of laser energy density on impulse coupling coefficient of laser ablation of water for propulsion

    Microsoft Academic Search

    C. Y. Cui; Y. J. Hong; J. F. Ye; M. Wen; N. L. Li

    2011-01-01

    Time-resolved force sensing and intensified charge-coupled device (ICCD) imaging techniques were applied to the study of the\\u000a effects of laser energy density on impulse coupling coefficient of laser ablation of water for propulsion. A Transversely\\u000a Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 ?m, 30 J pulse energy was used to ablate water contained in a quadrate quartz container. Net

  7. Rapid method for estimating the octanol–water partition coefficient (log P ow) by microemulsion electrokinetic chromatography

    Microsoft Academic Search

    Salwa K. Poole; Douglas Durham; Christopher Kibbey

    2000-01-01

    Several surfactant systems were evaluated based on their system constants determined by the solvation parameter model for the design of a surrogate chromatographic model for the rapid estimation of octanol–water partition coefficient (log Pow) by microemulsion electrokinetic chromatography. The system constant ratios responsible for the log Pow partition system are (nearly) the same as those for the microemulsion system containing

  8. Application of UNIFAC models to partition coefficients of biochemicals between water and n-octanol or n-butanol

    Microsoft Academic Search

    Hidetoshi Kuramochi; Hidetaka Noritomi; Daisuke Hoshino; Satoru Kato; Kunio Nagahama

    1998-01-01

    The objective of this work is to examine whether the various UNIFAC models can represent phase behavior of biochemicals in the dilution solution such as partition coefficients (log Pi). Especially, the log Pi of a solute in the n-octanol\\/water system was used as main target for the examination in this work. First, the log Pi of common chemical solutes was

  9. Estimation of octanol/water partition coefficient and aqueous solubility of environmental chemicals using molecular fingerprints and machine learning methods

    EPA Science Inventory

    Octanol/water partition coefficient (logP) and aqueous solubility (logS) are two important parameters in pharmacology and toxicology studies, and experimental measurements are usually time-consuming and expensive. In the present research, novel methods are presented for the estim...

  10. GRAPEVINE WATER USE AND CROP COEFFICIENT ARE LINEAR FUNCTIONS OF THE SHADED AREA MEASURED BENEATH THE CANOPY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relationships among water use and the crop coefficient of "Vitis vinifera" L. cv Thompson Seedless with several measures of canopy development were determined with the aid a weighing lysimeter in the San Joaquin Valley of California. At various times during two growing seasons, vine leaf area, c...

  11. Application of Peleg model to study water absorption in chickpea during soaking

    Microsoft Academic Search

    Mahir Turhan; Sedat Sayar; Sundaram Gunasekaran

    2002-01-01

    Application of the Peleg model was investigated for predicting water absorption by five winter- and five spring-planted chickpea genotypes during soaking between temperature (T ) of 20 and 100 °C. The Peleg model can predict kinetics of the chickpea soaking till equilibrium using short-term data at the given conditions. Its specific form for infinite time may also be used to

  12. TPS/PCL composite reinforced with treated sisal fibers: property, biodegradation and water-absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sisal fibers bleached with sodium-hydroxide followed by hydrogen peroxide treatment were incorporated in a thermoplastic starch;-polycaprolactone (TPS/PCL) blend via extrusion processing and examined for their property, biodegradability and water-absorption. Scanning electron microscopy revealed wel...

  13. DETERMINING BERYLLIUM IN DRINKING WATER BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROSCOPY

    EPA Science Inventory

    A direct graphite furnace atomic absorption spectroscopy method for the analysis of beryllium in drinking water has been derived from a method for determining beryllium in urine. Ammonium phosphomolybdate and ascorbic acid were employed as matrix modifiers. The matrix modifiers s...

  14. LEO-LEO OCCULTATIONS MEASURING WATER VAPOR AND TEMPERATURE VIA ABSORPTION

    E-print Network

    LEO-LEO OCCULTATIONS MEASURING WATER VAPOR AND TEMPERATURE VIA ABSORPTION S. Syndergaard, B. M, future LEO-LEO occultation constella- tions will be able to provide profiles of temperature and moisture vapor and ozone profiles from active microwave occultation measurements. In Fujisada, H., Lurie, J. B

  15. Absorption\\/regeneration non-conventional system for water extraction from atmospheric air

    Microsoft Academic Search

    Ahmed Sultan

    2004-01-01

    The present work suggests a non-conventional method of water production from atmospheric air, on a 24-h basis using a compact system. The operation of the system is described and its efficiency is defined. The system performs under forced convection absorption and regeneration through a packed tower. The packed tower consists of two identical columns, each of them is packed with

  16. Determination of ionic alkyllead compounds in water by gas chromatography\\/atomic absorption spectrometry

    Microsoft Academic Search

    D. Chakraborti; W. R. A. De Jonghe; W. E. Van Mol; R. J. A. Van Cleuvenbergen; F. C. Adams

    1984-01-01

    Ionic alkyllead compounds are extracted from water samples into pentane by complexation with sodium diethyldithiocarbamate. Inorganic lead is complexed with EDTA. The organic phase is evaporated to dryness by vacuum distillation, after which butylation with n-butyl Grignard reagent is carried out in a microvolume of n-nonane. The analysis is performed by gas chromatography with atomic absorption spectrometric detection. The effects

  17. Performance evaluation of a monomethylamine–water solar absorption refrigeration system for milk cooling purposes

    Microsoft Academic Search

    I. Pilatowsky; W. Rivera; J. R. Romero

    2004-01-01

    This study reports the applicability and the theoretical thermodynamic simulation of a solar driven monomethylamine–water single-stage absorption refrigeration cycle for milk cooling purposes in the rural regions of Mexico. A solar heating system using evacuated tube collectors coupled with a conventional auxiliary heating system is proposed. The simulation of the yearly dynamic behaviour of the solar system is carried out

  18. Ammonia absorption from a bubble expanding at a submerged orifice into water

    Microsoft Academic Search

    Koichi Terasaka; Junko Oka; Hideki Tsuge

    2002-01-01

    To investigate the mechanism of gas absorption from a bubble containing soluble and insoluble components, a gaseous mixture of ammonia and nitrogen was bubbled into water. The growth curve, volume, surface area and shape of the growing bubbles were measured with parameters such as inlet gas composition, gas flow rate and gas chamber volume. The bubble volume decreased with the

  19. Determination of water absorption and water holding capacities of different soil mixtures with MINIDRAIN system to enhance the plant growth

    NASA Astrophysics Data System (ADS)

    Sudan Acharya, Madhu; Rauchecker, Markus; Wu, Wei

    2014-05-01

    Soil water holding capacity is the amount of water that a given soil can hold against the force of gravity. Soil texture and organic matter are the key components that determine soil water holding capacity. Soils with smaller particle sizes, such as silt and clay have larger surface area can hold more water compared to sand which has large particle sizes which results in smaller surface area. A study report showed that 1% increase in soil humus will result in a 4% increase in stored soil water (Morris, 2004) and 1 part humus holds 4 parts of water (Wheeler and Ward, 1998). Therefore, the more humus that can be added to the soil, the greater the water holding capacity of the soil. As the level of organic matter increases in a soil, the water holding capacity also increases due to the affinity of organic matter for water. The water holding capacity of the soil is determined by the amount of water held in the soil sample vs. the dry weight of the sample. MINIDRAIN is a patented system made of geo-fabric (fleece) or combination of geosynthetics and humus. MINIDRAIN and vegetation nets developed by the company ÖKO-TEX (Linz, Austria) will improve the distribution of water and air in the soils, increase the growth of vegetation and reduce the soil erosion. Depending on the physical configuration, there are four different combinations of MINIDRAIN systems developed by ÖKO-TEX. a) Geotextile (fleece) strips of different sizes (e.g. 5x10x250 mm) b) Net formed strips (drainage nets) of different sizes c) Multilayer geotextile mats with humus, seeds or compost of different sizes (e.g. 10x30x200 mm) d) Multilayer geotextile net formed mats with humus, seeds or compost This paper describes the experimental results of the water absorption and water holding capacity of different forms of MINIDRAIN under different soil mixes. In this experiment, potting soil, coarse sand and LECA (Light weight clay aggregates) balls are mixed with different proportion of MINIDRAIN systems and the water absorption and water holding capacities are measured. A comparison of the results for an optimal combination of soil and MINIDRAIN system has also been made. The results show that, the soil mix with MINIDRAIN system with multilayer mats (with humus) have highest water absorption and water holding capacity among the tested soil mix combinations.

  20. Absorption and fluorescence properties of chromophoric dissolved organic matter: implications for the monitoring of water quality in a large subtropical reservoir.

    PubMed

    Liu, Xiaohan; Zhang, Yunlin; Shi, Kun; Zhu, Guangwei; Xu, Hai; Zhu, Mengyuan

    2014-12-01

    The development of techniques for real-time monitoring of water quality is of great importance for effectively managing inland water resources. In this study, we first analyzed the absorption and fluorescence properties in a large subtropical reservoir and then used a chromophoric dissolved organic matter (CDOM) fluorescence monitoring sensor to predict several water quality parameters including the total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), dissolved organic carbon (DOC), and CDOM fluorescence parallel factor analysis (PARAFAC) components in the reservoir. The CDOM absorption coefficient at 254 nm (a(254)), the humic-like component (C1), and the tryptophan-like component (C3) decreased significantly along a gradient from the northwest to the lake center, northeast, southwest, and southeast region in the reservoir. However, no significant spatial difference was found for the tyrosine-like component (C2), which contributed only four marked peaks. A highly significant linear correlation was found between the a(254) and CDOM concentration measured using the CDOM fluorescence sensor (r(2)?= 0.865, n = 76, p < 0.001), indicating that CDOM concentrations could act as a proxy for the CDOM absorption coefficient measured in the laboratory. Significant correlations were also found between the CDOM concentration and TN, TP, COD, DOC, and the maximum fluorescence intensity of C1, suggesting that the real-time monitoring of CDOM concentrations could be used to predict these water quality parameters and trace the humic-like fluorescence substance in clear aquatic ecosystems with DOC <2 mg/L and total suspended matter (TSM) concentrations <15 mg/L. These results demonstrate that the CDOM fluorescence sensor is a useful tool for on-line water quality monitoring if the empirical relationship between the CDOM concentration measured using the CDOM fluorescence sensor and the water quality parameters is calibrated and validated. PMID:25053284

  1. Estimation of amorphous organic carbon/water partition coefficients, subcooled aqueous solubilities, and n-octanol/water distribution coefficients of alkylbenzenes and polycyclic aromatic hydrocarbons.

    PubMed

    van Noort, Paul C M

    2009-02-01

    The aim of this work was to derive a relation between the number of specific carbon atoms in alkylbenzenes and PAHs and the average logK(oc) for linear partitioning between amorphous organic carbon in soils and sediments and water. The relation between the number of specific carbon atoms and n-octanol/water partitioning and subcooled aqueous solubility was sought first, as the number of data for partitioning into amorphous organic carbon was relatively sparse. It turned out that linear partitioning into amorphous organic carbon could be described by a linear relation based on the number of aromatic carbons, the number of alkyl carbons and the number of alicyclic carbons in the same way as for n-octanol/water partitioning and subcooled liquid aqueous solubility. From the linear regressions for linear partitioning into the various amorphous organic carbons, an average intercept for the linear partitioning regression equation was derived to represent average organic carbon in soils and sediments. PMID:19091377

  2. Coacervative extraction of trace lead from natural waters prior to its determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Hagarová, Ingrid; Bujdoš, Marek; Matúš, Peter; Kubová, Jana

    2013-10-01

    In this work, a relatively simple and sensitive method for separation/preconcentration of trace lead from natural waters prior to its determination by electrothermal atomic absorption spectrometry has been proposed. The method is based on the extraction of Pb-dithizone chelate with coacervates made up of lauric acid in the presence of potassium ions and methanol. Several important factors affecting extraction efficiency such as pH, concentration of lauric acid and dithizone, ionic strength, incubation and centrifugation time were investigated and optimized. After separation of aqueous bulk solution from surfactant-rich phase, the final extract was redissolved by using 500 ?l of methanol acidified with 0.2 mol l- 1 HNO3. Under the optimized conditions (using initial sample volume of 10 ml), enrichment factor of 17.0, detection limit of 0.12 ?g l- 1, quantification limit of 0.38 ?g l- 1, relative standard deviation of 4.2% (for 2 ?g l- 1 of Pb; n = 26), linearity of the calibration graph in the range of 0.5-4.0 ?g l- 1 (with correlation coefficient better than 0.995) were achieved. The method was validated by the analysis of certified reference material (TMDA-61). Extraction recoveries for the CRM, spiked model solutions and spiked natural water samples were in the range of 91-96%. Finally, the method was applied to the separation/preconcentration and determination of trace lead in natural waters.

  3. Comparative Study of Water Absorption Behavior of Wood and Wood Plastic Composites of Simul Using Film Neutron Radiography

    Microsoft Academic Search

    M. N. Islam; M. A. Khan; M. A. Zaman

    2005-01-01

    The film neutron radiography method was adopted for a comparative study of water absorption behavior in wood and wood plastic composites (WPC) of Simul using the thermal neutron radiography facility of 3 MW TRIGA MARK-II research reactor at Atomic Energy Research Establishment, Savar Dhaka, Bangladesh. Variations of optical density values due to water absorption of these samples were measured from neutron

  4. Inhibition of Ileal Water Absorption by Intraluminal Fatty Acids INFLUENCE OF CHAIN LENGTH, HYDROXYLATION, AND CONJUGATION OF FATTY ACIDS

    PubMed Central

    Ammon, Helmut V.; Phillips, Sidney F.

    1974-01-01

    The influence of fatty acids on ileal absorption of water, electrolytes, glucose, and taurocholate was examined in Thirty-Vella fistulas in five mongrel dogs. Fatty acid absorption also was measured. Segments of terminal ileum were perfused at steady state with isotonic electrolyte solutions containing 11.2 mM glucose, 4.5 mM taurocholate, and 0.1-5.0 mM fatty acid. Three C18 fatty acids, oleic acid, 10(9)-hydroxystearic acid, and ricinoleic acid, completely inhibited water absorption at 5 mM. Sodium, chloride, and potassium absorptions were inhibited in parallel with absorption of water. Differences between the potencies of C18 fatty acids were apparent when lesser concentrations were perfused. Dodecanoic and decanoic acids were as effective as C18 fatty acids at 5 mM but octanoic and hexanoic acids were ineffective. The polar group of C18 fatty acids was modified by conjugating oleic and ricinoleic acids with taurine. When these compounds and a substituted C18 fatty acid, p-n-decylbenzenesulfonate, were perfused, water absorption was also inhibited. Short-chain fatty acids (C3 and C4) and their hydroxylated derivatives were ineffective at 5 mM. When water absorption was inhibited, absorption of glucose and taurocholate was decreased. We speculate that the phenomenon of inhibition of water and electrolyte absorption by fatty acids may be relevant to steatorrhea and diarrhea in man. Images PMID:4808636

  5. Low frequency sound absorption in sea water: A new chemical relaxation

    NASA Astrophysics Data System (ADS)

    Browning, D. G.; Mellen, R. H.; Simmons, V. P.

    1981-09-01

    This document presented the oral and visual presentation entitled 'Low Frequency Sound Absorption in Sea Water: A New Chemical Relaxation Mechanism?,' presented at the 101st Meeting of the Acoustical Society of America, 18-22 May 1981, in Ottawa, Ontario, Canada. Excess sound absorption in sea water arises mainly from chemical relaxations involving MgS04 and B(OH)3. The high-frequency (100 kHz) MgS04 relaxation has been identified as a multistep ion-pair process. The low frequency (1 kHz) and B(OH)3 relaxation apparently involves more complex interactions with other constituents. To investigate B(OH)3 interactions in a simpler system, we measured absorption in NH3 solution using the resonator method. We have found alpha max to be proportional to the product of NH(+) and B(OH)4(-) concentrations; however, the magnitude is much too large to be caused by the ion pair. The mechanism, probably similar to that in sea water, resembles catalysis, the absorption being governed by the large volume change of the faster NH3/NH4(+) equilibrium and the relaxation frequency by the slower B(OH)3/B(OH)4(-) equilibrium.

  6. The phase behavior and absorption spectra of the ternary system cobaltous chloride-water-acetonitrile

    E-print Network

    Bobbitt, Jeffrey Lovett

    1967-01-01

    . HE PHASZ BEHAVIOR ARD ABSORPTION SPECTRA. OF THE TER1MRY SYSTEN COBALTOUS CHLORIDE-WATER-AGZTOIJITRILE A Thesis by JEFFREY LOVZTT BOBBIT'1 Submitted to the Graduate College of the Texas A&N University in Partial fulfillment... of the recuirements tor the d. egrce of PlASTER OF SCIENCE Nay 1967 Najor Subject: GHENISTRY THE PHASE BIEIAVIOR Al'TD ABSORPTION SPZCTR4 OF TIIE TERNARY SYSTZNi COBAI, TOUS C&ILORIDZ-WATZR-ACZTONITRIIR A Thesis by JEFFREY I OVl'TT B013BITT APProved...

  7. Determination of traces of silver in waters by anion exchange and atomic absorption spectrophotometry

    USGS Publications Warehouse

    Chao, T.T.; Fishman, M.J.; Ball, J.W.

    1969-01-01

    A method has been developed for the accurate determination of 0.1-1 ??g of silver per liter of water. The method permits stabilization of silver in water without loss to container walls. Optimum conditions have been established for the complete recovery of silver from water with an anion-exchange column, for quantitative elution of silver from the resin, and for measurement of silver by atomic absorption spectrophotometry after chelation with ammonium pyrrolidine dithiocarbamate and extraction of the chelate with MIBK. Silver in the 1-10 ??g 1 range can be determined by extraction without pre-concentration on an ion-exchange resin. ?? 1969.

  8. Capacity for Absorption of Water-Soluble Secondary Metabolites Greater in Birds than in Rodents

    PubMed Central

    Karasov, William H.; Caviedes-Vidal, Enrique; Bakken, Bradley Hartman; Izhaki, Ido; Samuni-Blank, Michal; Arad, Zeev

    2012-01-01

    Plant secondary metabolites (SMs) are pervasive in animal foods and potentially influence feeding behavior, interspecies interactions, and the distribution and abundance of animals. Some of the major classes of naturally occurring SMs in plants include many water-soluble compounds in the molecular size range that could cross the intestinal epithelium via the paracellular space by diffusion or solvent drag. There are differences among species in paracellular permeability. Using Middle Eastern rodent and avian consumers of fruits containing SMs, we tested the hypothesis that avian species would have significantly higher paracellular permeability than rodent species. Permeability in intact animals was assessed using standard pharmacological methodology to measure absorption of two radiolabeled, inert, neutral water-soluble probes that do not interact with intestinal nutrient transporters, L-arabinose (Mr?=?150.1 Da) and lactulose (Mr?=?342.3 Da). We also measured absorption of labeled 3-O-methyl-D-glucose (3OMD-glucose; Mr?=?194.2 Da), which is a nonmetabolized analogue of D-glucose that is passively absorbed through the paracellular space but also transported across the enterocyte membranes. Most glucose was absorbed by all species, but arabinose fractional absorption (f) was nearly three times higher in birds (1.03±0.17, n?=?15 in two species) compared to rodents (0.37±0.06, n?=?10 in two species) (P<0.001). Surprisingly, the apparent rates of absorption in birds of arabinose exceeded those of 3OMD-glucose. Our findings are in agreement with previous work showing that the paracellular pathway is more prominent in birds relative to nonflying mammals, and suggests that birds may be challenged by greater absorption of water-soluble, dietary SMs. The increased expression of the paracellular pathway in birds hints at a tradeoff: the free energy birds gain by absorbing water-soluble nutrients passively may be offset by the metabolic demands placed on them to eliminate concomitantly absorbed SMs. PMID:22389702

  9. The water vapour self- and water-nitrogen continuum absorption in the 1000 and 2500 cm(-1) atmospheric windows.

    PubMed

    Baranov, Yu I; Lafferty, W J

    2012-06-13

    The pure water vapour and water-nitrogen continuum absorption in the 1000 and 2500?cm(-1) atmospheric windows has been studied using a 2?m base-length White-type multi-pass cell coupled with a BOMEM DA3-002 Fourier transform infrared spectrometer. The measurements were carried out at the National Institute of Standards and Technology (NIST, Gaithersburg, MD) over the course of several years (2004, 2006-2007, 2009). New data on the H(2)O:N(2) continuum in the 1000?cm(-1) window are presented and summarized along with the other experimental results and the continuum model. The experimental data reported on the water vapour continuum in these atmospheric windows basically agree with the most reliable laboratory data from the other sources. The MT_CKD (Mlawer-Tobin-Clough-Kneizys-Davies) continuum model significantly departs from the experimental data in both windows. The deviation observed includes the continuum magnitude, spectral behaviour and temperature dependence. In the 2500?cm(-1) region, the model does not allow for the nitrogen fundamental collision-induced absorption (CIA) band intensity enhancement caused by H(2)O:N(2) collisions and underestimates the actual absorption by over two orders of magnitude. The water vapour continuum interpretation as a typical CIA spectrum is reviewed and discussed. PMID:22547233

  10. The sublimation coefficient of water ice: influence on the temperature and outgassing of Comet 67P/C-G

    NASA Astrophysics Data System (ADS)

    Kossacki, K. J.; Markiewicz, W. J.

    2013-09-01

    In most published works dealing with evolution of cometary nuclei, the sublimation rate of ices is calculated with simple Hertz-Knudsen equation. This formulation, derived from the kinetic theory of gases, ignores microphysical processes which determine the sublimation rate. To correctly account for these processes the modified Herz-Knudsen equation must include temperature dependent sublimation coefficient. Including this temperature dependence we find, that the temperature below dust mantle is most sensitive to the value of the sublimation coefficient when the mantle is coarse grained, while the sublimation rate is most affected when the mantle is fine grained. Most importantly, we also find that derivation of the temperature below the dust mantle from the measured water production rate ignoring temperature dependence of the sublimation coefficient can lead to an underestimate of the sub-dust temperature by more than 10 K.

  11. Polymer-water partition coefficients of hydrophobic compounds for passive sampling: application of cosolvent models for validation.

    PubMed

    Smedes, Foppe; Geertsma, Rinze W; van der Zande, Ton; Booij, Kees

    2009-09-15

    Polymer-water partition coefficients (Kpw) of hexachlorobenzene, 41 polychlorinated biphenyls (PCBs), and 26 polyaromatic hydrocarbons (PAHs) were determined for low-density polyethylene (LDPE) and five different silicone rubbers. Partition coefficients were determined in ultra pure water and in a range of methanol-water mixtures. Different cosolvent models for the effect of methanol concentration on the polymer-mixture partition coefficient (Kpm) were used to validate the Kpw in pure water. Linear regression of logKpm against the mole fraction (x) methanol over range 0 < x < 0.3 yielded the best results. The obtained logKpws were best described by a correlation with molecular weight, for PCBs in combination with the fraction of chlorine atoms in the meta and para positions (standard deviations of approximately 0.08 log units). Correlations with logKow were less good (standard deviations of approximately 0.21 log units), partly as a result of uncertainties in the logKow estimates that were used. Similar Kpws were found for different batches of silicone rubber from the same supplier. Differences in logKpws for silicone rubbers obtained from different suppliers ranged from 0.16-0.58. PMID:19806740

  12. Comparison of polar motion excitation function derived from equivalent water thickness data, obtained from filtered stokes coefficients

    NASA Astrophysics Data System (ADS)

    Nagalski, T.

    2012-12-01

    It is known that the estimates of the Earth's gravity field produced by the Gravity Recovery and Climate Experiment (GRACE) satellite mission can be used to infer changes in equivalent water thickness (EWT). However, inadequately smoothed GRACE satellite mission EWT data contain significant striping and thus ought to be filtered to improve signal to noise ratio. We used Stokes coefficients data from GFZ (GeoForschungsZentrum), JPL (Jet Propulsion Laboratory) and CSR (Center for Space Research), filtered by decorrelation anisotropic filters: DDK3, DDK2 and DDK1 (Kusche et al., 2009) and made available in the ICGEM (International Center for Global Earth Models). To determine gravimetric excitation function of polar motion for the entire globe or selected areas, we convert gravity coefficients into Equivalent Water Thickness fields. To eliminate stripes from the maps of the EWT, one uses anisotropic filters (Kusche et al., 2009) that are smoothing the EWT data. In this study we investigate the influence of decorrelation anisotropic DDK filters used to process the GRACE EWT fields on the determined polar motion gravimetric excitation functions. We investigate the effect of these filters for four regions: 1) entire Earth, 2) ocean area, 3) land area and 4) Tibetan Plateau area (a rectangle bounded by 4 points A(37.N,78.E), B(37.N,102.E), C(28.N,78.E), D(28.N,102.E). Stokes coefficients are made available on the ICGEM web site. The data contain spherical harmonic coefficients delivered by three research centers: CSR, GFZ, JPL. The time span of the data is 2002 - 2010. The time resolution is 30 days. The ICGEM delivers either the raw Stokes coefficients or filtered Stokes coefficients after application of the anisotropic filters. Computation were based on the following equations

  13. Effect of chitosan on gastrointestinal absorption of water-insoluble drugs following oral administration in rats.

    PubMed

    Nadai, Masayuki; Tajiri, Chiharu; Yoshizumi, Hideo; Suzuki, Yuji; Zhao, Ying Lan; Kimura, Masao; Tsunekawa, Yoshimi; Hasegawa, Takaaki

    2006-09-01

    Chitosan is widely used as a dietary weight-loss supplement in Japan. In the present study, we examined the effect of chitosan on the gastrointestinal absorption profiles of the water-insoluble drugs, indomethacin and griseofulvin, and the water-soluble drugs, acetaminophen and cephalexin, after oral administration in rats. Rats received oral administration of chitosan (5 mg/kg or 25 mg/kg) dissolved in 5% acetic acid or vehicle 15 min before oral administration of each drug. Chitosan at a dose of 25 mg/kg, but not 5 mg/kg, significantly decreased the plasma concentrations of indomethacin and griseofulvin after administration as a suspension with a significant delay of the time to reach maximum concentration compared to the corresponding control values (vehicle-pretreated rats). However, pretreatment of chitosan (25 mg/kg) did not change the pharmacokinetics of indomethacin administered as a solution. Further, the same dose of chitosan had no effect on the pharmacokinetics of acetaminophen. The gastrointestinal absorption profile of an amino-beta-lactam antibiotic, cephalexin, which is actively absorbed via carrier-mediated transport system, was also unchanged. The present findings at least suggest the possibility that chitosan at high dose reduces the gastrointestinal absorption of water-insoluble drugs such as indomethacin and griseofulvin, but not water-soluble drugs, by diminishing the surfactant-like effect of bile acids. PMID:16946514

  14. A quantitative structure-property relationship analysis of soot-water partition coefficients for persistent organic pollutants.

    PubMed

    Xu, Hui-Ying; Zou, Jian-Wei; Min, Jian-Qing; Wang, Wei

    2012-06-01

    Geometrical optimization and electrostatic potential calculations have been performed at the HF/6-31G level of theory for investigated persistent organic pollutants (POPs). A number of statistically based parameters have been obtained. Relationship between soot-water partition coefficients (logK(SC)) of POPs and the structural descriptors has been established by the multiple linear regression method. The result shows that the quantities derived from electrostatic potential V(s)(-)¯ and V(s,max), together with molecular surface area (A(S)) and the energy of the highest occupied molecular orbital (E(HOMO)) can be well used to express the quantitative relationship between structure and logK(SC) (QSPR) of POPs. Predictive capability of the model has been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient of 0.9797. Furthermore, the predictive power of this model was further examined for the external test set with the correlation coefficient of 0.9811 between observed and predicted logK(SC), validating the robustness and good predictive ability of our model. Furthermore, in order to further investigate the applicability of these parameters derived from electrostatic potential in prediction of soot-water partition coefficient for organic pollutants, eleven polycyclic aromatic hydrocarbons (PAHs), eleven polychlorinated biphenyls (PCBs) and nine phenyl urea herbicides (PUHs) from other source have also been studied. The QSPR models established may provide a new powerful method for predicting soot-water partition coefficients (logK(SC)) of organic pollutants. PMID:22377400

  15. A yearlong study of water-soluble organic carbon in Beijing II: Light absorption properties

    NASA Astrophysics Data System (ADS)

    Du, Zhenyu; He, Kebin; Cheng, Yuan; Duan, Fengkui; Ma, Yongliang; Liu, Jiumeng; Zhang, Xiaolu; Zheng, Mei; Weber, Rodney

    2014-06-01

    Light absorption properties of water-soluble organic carbon (WSOC) in Beijing were investigated by 24 h-averaged fine particulate matter (PM2.5) samples collected from October 2010 to November 2011. The light absorption spectra of WSOC exhibited strong wavelength dependence such that the absorption Ångstrom exponent was approximately 7.5. The light absorption at 365 nm (Abs365), which is typically used as a proxy of water-soluble brown carbon, was found to correlate strongly with WSOC (R2 > 0.75, p < 0.01). Moreover, the correlation between Abs365 and levoglucosan (especially in fall and winter) indicated that biomass burning could contribute significantly to water-soluble brown carbon. Source apportionment with Positive Matrix Factorization (PMF) model showed that biomass burning and mixed sources contributed 58.0% and 20.8% to total Abs365, compared with 21.2% from WSOC associated with sulfate and oxalate. The mass absorption efficiency (MAE) of WSOC in Beijing showed distinct temporal variations (averaging 1.26 m2/g and 0.51 m2/g during winter and summer, respectively), and was approximately 2-3 times the values of that observed in the southeastern United States, but was substantially lower than the summertime results from Los Angeles. Influence factors responsible for the temporal and spatial variations of MAE were investigated. MAE were calculated for each PMF factor. It was found that the MAE for WSOC from biomass burning (1.19 m2/g) and mixed primary sources (2.89 m2/g) was much higher than that of WSOC associated with sulfate or oxalate (0.32-0.33 m2/g) in Beijing. In addition, it was concluded that differences in the precursors of WSOC might also be responsible for the observed variation of MAE such that WSOC associated with anthropogenic precursors are more light-absorbing compared with WSOC biogenic sources.

  16. Volatilization of ethylene dibromide from water

    USGS Publications Warehouse

    Rathbun, R.E.; Tai, D.Y.

    1987-01-01

    Overall mass-transfer coefficients for the volatilization of ethylene dibromide from water were measured simultaneously with the oxygen absorption coefficient in a laboratory stirred tank. Coefficients were measured as a function of mixing conditions in the water for two windspeeds. The ethylene dibromide mass-transfer coefficient depended on windspeed; the ethylene dibromide liquid-film coefficient did not, in agreement with theory. A constant relation existed between the liquid-film coefficients for ethylene dibromide and oxygen.

  17. Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet.

    PubMed

    Fraine, Jonathan; Deming, Drake; Benneke, Bjorn; Knutson, Heather; Jordán, Andrés; Espinoza, Néstor; Madhusudhan, Nikku; Wilkins, Ashlee; Todorov, Kamen

    2014-09-25

    Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain atmospheres with high mean molecular weights (little hydrogen), opaque clouds or scattering hazes, reducing our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of the exoplanet HAT-P-11b (which has a radius about four times that of Earth) from the optical wavelength range to the infrared. We detected water vapour absorption at a wavelength of 1.4 micrometres. The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e). The spectrum is indicative of a planetary atmosphere in which the abundance of heavy elements is no greater than about 700 times the solar value. This is in good agreement with the core-accretion theory of planet formation, in which a gas giant planet acquires its atmosphere by accreting hydrogen-rich gas directly from the protoplanetary nebula onto a large rocky or icy core. PMID:25254473

  18. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    SciTech Connect

    Anheier, N.C. Jr.; McDonald, C.E.; Cuta, J.M.; Cuta, F.M.; Olsen, K.B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose of this work was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. PNL researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH{sub 4}{sup +}). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  19. Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet

    NASA Astrophysics Data System (ADS)

    Fraine, Jonathan; Deming, Drake; Benneke, Bjorn; Knutson, Heather; Jordán, Andrés; Espinoza, Néstor; Madhusudhan, Nikku; Wilkins, Ashlee; Todorov, Kamen

    2014-09-01

    Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain atmospheres with high mean molecular weights (little hydrogen), opaque clouds or scattering hazes, reducing our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of the exoplanet HAT-P-11b (which has a radius about four times that of Earth) from the optical wavelength range to the infrared. We detected water vapour absorption at a wavelength of 1.4 micrometres. The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e). The spectrum is indicative of a planetary atmosphere in which the abundance of heavy elements is no greater than about 700 times the solar value. This is in good agreement with the core-accretion theory of planet formation, in which a gas giant planet acquires its atmosphere by accreting hydrogen-rich gas directly from the protoplanetary nebula onto a large rocky or icy core.

  20. Equilibrium phase diagrams and water absorption properties of aqueous mixtures of malonic acid and inorganic salts.

    NASA Astrophysics Data System (ADS)

    Salcedo, D.; Salgado-Olea, G.

    2006-12-01

    Tropospheric aerosols are usually complex mixtures of inorganic and organic components. Although the thermodynamic properties of inorganic aerosols have been widely studied, the effect of organics on such properties is still under discussion. Solubility in water, water activity of aqueous solutions, deliquescence relative humidity (DRH), eutonic composition, and eutonic DRH were determined for bulk mixtures of malonic acid with ammonium sulfate, ammonium bisulfate, and ammonium nitrate at 25oC over the full range of composition (from 0 wt% to the solubility limit of the mixture components). The data was used to construct equilibrium phase diagrams, which show the phase of the mixtures as a function of total composition, dry mixture composition, water content, and ambient relative humidity. Measured water activity of liquid solutions was compared with an extended Zdanovskii-Stokes-Robinson (ZSR) expression, which then was used to predict water absorption of the mixtures.

  1. Water–sulphur dioxide association. Second virial cross coefficients for water–sulphur dioxide derived from gas phase excess enthalpy measurements

    Microsoft Academic Search

    C. J Wormald

    2003-01-01

    A flow mixing calorimeter has been used to measure the excess molar enthalpy HmE of gaseous (water+sulphur dioxide) at the mole fraction y=0.5, at standard atmospheric pressure, and over the temperature range (383.2 to 483.2K). Information about the strength of the water–sulphur dioxide interaction was obtained by analysing the measurements using a quasi-chemical association model. The second virial coefficient B11

  2. Physicochemical properties of polycyclic aromatic hydrocarbons: Aqueous solubilities, n-octanol\\/water partition coefficients, and Henry`s law constants

    Microsoft Academic Search

    P. Gert-Jan de Maagd; A. Opperhuizen; D. T. H. M. Sijm; D. T. E. M. ten Hulscher; H. van den Heuvel

    1998-01-01

    Aqueous solubilities, n-octanol\\/water partition coefficients (K{sub ow}S), and Henry`s law constants were determined for a range of polycyclic aromatic hydrocarbons (PAHs) using a generator-column, slow-stirring, and gas-purge method, respectively. The currently obtained data were compared to available literature data. For seven of the PAHs no K{sub ow}S previously were determined with the slow-stirring method. For four of the PAHs the

  3. Chromatographic determination of octanol-water partition coefficients (K\\/sub ow\\/'s) for 58 polychlorinated biphenyl congeners

    Microsoft Academic Search

    R. A. Rapaport; S. J. Eisenreich

    1984-01-01

    Octanol-water partition coefficients of 58 poly-chlorinated biphenyl (PCB) congeners have been determined by reverse-phase Cââ high-performance liquid chromatography (HPLC) of Aroclor 1242 and 1254 mixtures. High-resolution glass capillary gas-liquid chromatography was used for the detection of the eluted individual congeners. Some PCB congeners behaved atypically from other organics on reverse-phase HPLC, and empirically derived correction factors were used to adjust

  4. Estimation of n-octanol\\/water partition coefficients ( K ow) of all PCB congeners by density functional theory

    Microsoft Academic Search

    Wen Zhou; Zhicai Zhai; Zunyao Wang; Liansheng Wang

    2005-01-01

    Optimized calculation of 209 PCBs was carried out at B3LYP\\/6-31G* level in gaussian98 program. Based on the theoretical linear solvation energy relationship (TLSER) model, the obtained structural parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting n-octanol\\/water partition coefficients (lgKow) of PCBs. The new model achieved in this work contains three variables, polarizability ?, ELUMO

  5. Dietary accumulation and depuration of hydrophobic organochlorines: Bioaccumulation parameters and their relationship with the octanol\\/water partition coefficient

    Microsoft Academic Search

    Aaron T. Fisk; Ross J. Norstrom; Chris D. Cymbalisty; Derek C. G. Muir

    1998-01-01

    Dietary accumulation of 23 hydrophobic organochlorines (OCs) by juvenile rainbow trout (Oncorhynchus mykiss) was studied with the objective of obtaining relationships between bioaccumulation parameters and the octanol\\/water partition coefficient (K{sub ow}). A wide range of OCs were used including 16 polychlorinated biphenyls, hexachlorobenzene, mirex, tris(4-chlorophenyl)methane (TCPMe), tris(4-chlorophenyl)methanol (TCPMeOH), and three toxaphene congeners. With the exception of TCPMeOH, Clâ-CHB, and PCB

  6. QSPR models of boiling point, octanol–water partition coefficient and retention time index of polycyclic aromatic hydrocarbons

    Microsoft Academic Search

    Fabiana Alves de Lima Ribeiro; Márcia Miguel Castro Ferreira

    2003-01-01

    A Quantitative Structure–Property Relationship (QSPR) analysis and study of polycyclic aromatic hydrocarbons (PAHs) is presented. Three physicochemical properties related to their environmental impact are studied: boiling point (bp), octanol–water partition coefficient (logKow) and retention time index (RI) for reversed-phase liquid chromatography analysis. The geometry of all PAHs were optimized by the semi-empirical method AM1 and used to calculate thermodynamic, electronic,

  7. Calculation of the X-ray absorption spectrum of liquid water and ice

    Microsoft Academic Search

    Balazs Hetenyi; Paolo Giannozzi; Roberto Car

    2001-01-01

    We calculate the near-edge X-ray absorption fine structure (NEXAFS) spectrum of water in the gas liquid and solid (cubic) phases. We use density functional theory in the gas and solid phases and ab initio molecular dynamics to generate liquid phase configurations at a temperature of 300K. Subsequently, we calculate oscillator strengths between the 1s state of each oxygen atom and

  8. Relationship of Kernel Size to Flour Water Absorption for Canada Western Red Spring Wheat

    Microsoft Academic Search

    B. C. Morgan; J. E. Dexter; K. R. Preston

    2000-01-01

    Cereal Chem. 77(3):286-292 Canada Western Red Spring (CWRS) wheat exhibits consistent posi- tive relationships between kernel weight and farinograph and baking water absorption. These relationships are sufficiently robust to be statistically significant (P < 0.05) for historical Canadian Grain Commission harvest survey data generated one year apart for 17 years, and for historical data on individual cultivars in advanced Canadian

  9. Comparative simulation and investigation of ammonia-water: absorption cycles for heat pump applications

    Microsoft Academic Search

    M Engler; G Grossman; H.-M Hellmann

    1997-01-01

    Several recent programs in absorption research have focused on technology for domestic heating and cooling utilizing natural gas. In residential and small commercial size applications, ammonia-water cycles offer the possibility of a gas-fired heat pump for both winter heating and summer cooling, at better year-round COPS than currently available by various alternatives. Several cycles have been considered for this purpose,

  10. CO2 Absorption Rate and Solubility in Monoethanolamine\\/Piperazine\\/Water

    Microsoft Academic Search

    Gary T. Rochelle

    2003-01-01

    The solubility and absorption rate of carbon dioxide into monoethanolamine\\/ piperazine\\/water were measured in a wetted wall column at 40-60°C. The total amine concentration was varied from 1.0 M to 5.0 M with monoethanolamine blends containing 0 to 1.2 M piperazine. CO2 solubility and solution speciation were simulated by nine equilibrium reactions. Two of the equilibrium constants were adjusted to

  11. CO2 Absorption Rate and Solubility in Monoethanolamine\\/Piperazine\\/Water

    Microsoft Academic Search

    Hongyi Dang; Gary T. Rochelle

    2003-01-01

    The solubility and absorption rate of carbon dioxide into monoethanolamine\\/piperazine\\/water were measured in a wetted wall column at 40–60°C. The total amine concentration was varied from 1.0 M to 5.0 M, with monoethanolamine blends containing 0 to 1.2 M piperazine. CO2 solubility and solution speciation were simulated by nine equilibrium reactions. Two of the equilibrium constants were adjusted to match literature data. The

  12. Kinetics of absorption of carbon dioxide into solutions of N-methyldiethanolamine+water

    Microsoft Academic Search

    Jiun-Jie Ko; Meng-Hui Li

    2000-01-01

    Kinetics of the absorption of CO2 into N-methyldiethanolamine (MDEA)+water were investigated at 30, 35, and 40°C using a laboratory wetted wall column. Four systems of which 1.0, 1.5, 2.0, and 2.5kmolm?3 MDEA aqueous solutions were studied. The solubility and the diffusivity of N2O in amine systems were also studied. The N2O analogy was applied to estimate the solubility and the

  13. Henry's Law Constant and Overall Mass Transfer Coefficient for Formaldehyde Emission from Small Water Pools under Simulated Indoor Environmental Conditions.

    PubMed

    Liu, Xiaoyu; Guo, Zhishi; Roache, Nancy F; Mocka, Corey A; Allen, Matt R; Mason, Mark A

    2015-02-01

    The Henry's law constant (HLC) and the overall mass transfer coefficient are both important parameters for modeling formaldehyde emissions from aqueous solutions. In this work, the apparent HLCs for formaldehyde aqueous solutions were determined in the concentration range from 0.01% to 1% (w/w) and at different temperatures (23, 40, and 55 °C) by a static headspace extraction method. The aqueous solutions tested included formaldehyde in water, formaldehyde-water with nonionic surfactant Tergitol NP-9, and formaldehyde-water with anionic surfactant sodium dodecyl sulfate. Overall, the measured HLCs ranged from 8.33 × 10(-6) to 1.12 × 10(-4) (gas-concentration/aqueous-concentration, dimensionless). Fourteen small-chamber tests were conducted with formaldehyde solutions in small pools. By applying the measured HLCs, the formaldehyde overall liquid-phase mass transfer coefficients (KOLs) were determined to be in the range of 8.12 × 10(-5) to 2.30 × 10(-4) m/h, and the overall gas-phase mass transfer coefficients were between 2.84 and 13.4 m/h. The influences of the formaldehyde concentration, temperature, agitation rate, and surfactant on HLC and KOL were investigated. This study provides useful data to support source modeling for indoor formaldehyde originating from the use of household products that contain formaldehyde-releasing biocides. PMID:25564098

  14. Assessment of underwater irradiance and absorption of solar radiation at water column from satellite data

    NASA Astrophysics Data System (ADS)

    Kopelevich, Oleg V.; Sheberstov, Sergey V.; Burenkov, Vladimir I.; Vazyulya, Svetlana V.; Likhacheva, Maria V.

    2007-04-01

    The volume absorption of solar radiation in water body determines important processes in the upper ocean such as primary bioproduction and heat balance. Assessment of penetration of solar radiation into water body can be performed with satellite data and the previous attempts in this direction were promising. This paper presents a package of the algorithms to compute the components of balance of photosynthetically available radiation (PAR) at sea level (incident, reflected from the rough sea surface, and water-leaving PAR) and to calculate the volume absorption of PAR in the upper layer from satellite ocean color data. Data measured by the SeaWiFS ocean color sensor and the ancillary data needed (such as ozone amount and wind speed) are used. Computations of the underwater irradiance are performed for the 0-25 m upper layer. The errors are estimated by direct comparison between the values of underwater irradiance and volume absorption derived by the algorithms developed and by the exact method. Monthly means of the components of PAR balance as well as the potential daily heating have been estimated in different regions.

  15. Automated atomic absorption spectrometric determination of total arsenic in water and streambed materials

    USGS Publications Warehouse

    Fishman, M.

    1977-01-01

    An automated method to determine both inorganic and organic forms of arsenic In water, water-suspended mixtures, and streambed materials Is described. Organic arsenic-containing compounds are decomposed by either ultraviolet radiation or by suHurlc acid-potassium persulfate digestion. The arsenic liberated, with Inorganic arsenic originally present, is reduced to arsine with sodium borohydrlde. The arable Is stripped from the solution with the aid of nitrogen and Is then decomposed In a tube furnace heated to 800 ??C which Is placed in the optical path of an atomic absorption spectrometer. Thirty samples per hour can be analyzed to levels of 1 ??g arsenic per liter.

  16. Determination of ionic alkyllead compounds in water by gas chromatography/atomic absorption spectrometry

    SciTech Connect

    Chakraborti, D.; De Jonghe, W.R.A.; Van Mol, W.E.; Van Cleuvenbergen, R.J.A.; Adams, F.C.

    1984-01-01

    Ionic alkyllead compounds are extracted from water samples into pentane by complexation with sodium diethyldithiocarbamate. Inorganic lead is complexed with EDTA. The organic phase is evaporated to dryness by vacuum distillation, after which butylation with n-butyl Grignard reagent is carried out in a microvolume of n-nonane. The analysis is performed by gas chromatography with atomic absorption spectrometric detection. The effects of various parameters on the analytical performance are discussed. With 500 mL of water, detection limits for individual species are situated at the ng.L/sup -1/ level.

  17. Differential absorption and Raman lidar for water vapor profile measurements - A review

    NASA Technical Reports Server (NTRS)

    Grant, William B.

    1991-01-01

    Differential absorption lidar and Raman lidar have been applied to the range-resolved measurements of water vapor density for more than 20 years. Results have been obtained using both lidar techniques that have led to improved understanding of water vapor distributions in the atmosphere. This paper reviews the theory of the measurements, including the sources of systematic and random error; the progress in lidar technology and techniques during that period, including a brief look at some of the lidar systems in development or proposed; and the steps being taken to improve such lidar systems.

  18. Water vapor absorption spectra of the upper atmosphere /45-185 per cm/

    NASA Technical Reports Server (NTRS)

    Augason, G. C.; Mord, A. J.; Witteborn, F. C.; Erickson, E. F.; Swift, C. D.; Caroff, L. J.; Kunz, L. W.

    1975-01-01

    The far IR nighttime absorption spectrum of the earth's atmosphere above 14 km is determined from observations of the bright moon. The spectra were obtained using a Michelson interferometer attached to a 30-cm telescope aboard a high-altitude jet aircraft. Comparison with a single-layer model atmosphere implies a vertical column of 3.4 plus or minus 0.4 microns of precipitable water on 30 August 1971 and 2.4 plus or minus 0.3 microns of precipitable water on 6 January 1972.-

  19. Modeling the vertical distributions of downwelling plane irradiance and diffuse attenuation coefficient in optically deep waters

    Microsoft Academic Search

    Xiaoju Pan; Richard C. Zimmerman

    2010-01-01

    The diffuse attenuation coefficient (Kd) is critical to understand the vertical distribution of underwater downwelling irradiance (Ed). Theoretically Ed is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kd is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse

  20. Human skin binding and absorption of contaminants from ground and surface water during swimming and bathing

    SciTech Connect

    Wester, R.C.; Maibach, H.I. (California Univ., San Francisco (USA))

    1989-10-01

    Contaminants exist in ground and surface water. Human skin has the capacity to bind and then absorb these contaminants into the body during swimming and bathing. Powdered human stratum corneum will bind both lipid-soluble (alachlor, polychlorinated biphenyls (PCBs), benzene) and water-soluble (nitroaniline) chemicals. In vitro (Human skin) and in vivo (Rhesus monkey) studies show that these chemicals readily distribute into skin, and then some of the chemical is absorbed into the body. Linearity in binding and absorption exists for nitroaniline over a 10-fold concentration range. Multiple exposure to benzene is at least cumulative. Binding and adsorption can be significant for exposures as short as 30 minutes, and will increase with time. Adsorption with water dilution increased for alachlor, but not for dinoseb. Soap reversed the partitioning of alachlor between human stratum corneum and water. The PCBs could be removed from skin by soap and water for up to 3 hours and the decontamination potential decreased, due to continuing skin absorption. The model that in vitro and in vivo systems used should permit easy estimation of this area of extensive human exposure effect on risk assessment. 5 refs., 9 tabs.

  1. In-Line Capacitance Sensor for Real-Time Water Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Nurge, Mark A.; Perusich, Stephen A.

    2010-01-01

    A capacitance/dielectric sensor was designed, constructed, and used to measure in real time the in-situ water concentration in a desiccant water bed. Measurements were carried out with two experimental setups: (1) passing nitrogen through a humidity generator and allowing the gas stream to become saturated at a measured temperature and pressure, and (2) injecting water via a syringe pump into a nitrogen stream. Both water vapor generating devices were attached to a downstream vertically-mounted water capture bed filled with 19.5 g of Moisture Gone desiccant. The sensor consisted of two electrodes: (1) a 1/8" dia stainless steel rod placed in the middle of the bed and (2) the outer shell of the stainless steel bed concentric with the rod. All phases of the water capture process (background, heating, absorption, desorption, and cooling) were monitored with capacitance. The measured capacitance was found to vary linearly with the water content in the bed at frequencies above 100 kHz indicating dipolar motion dominated the signal; below this frequency, ionic motion caused nonlinearities in the water concentration/capacitance relationship. The desiccant exhibited a dielectric relaxation whose activation energy was lowered upon addition of water indicating either a less hindered rotational motion or crystal reorientation.

  2. Protein-water network dynamics during metalloenzyme hydrolysis observed by kinetic THz absorption (KITA)

    NASA Astrophysics Data System (ADS)

    Born, Benjamin; Heyden, Matthias; Grossman, Moran; Sagi, Irit; Havenith, Martina

    2013-02-01

    For long, the contribution of water network motions to enzymatic reactions was enigmatic due to the complexity of biological systems and to experimental limitations. Thanks to the development of new powerful THz emitters and detectors in the last decades, it is now possible to probe dynamics on the timescale of the fast hydrogen bond rearrangements during biochemical reactions. For this purpose, we developed a kinetic terahertz absorption (KITA) spectrometer which combines the strength of THz radiation (~1012 Hz = 1 ps) to directly probe collective picosecond protein-water dynamics with the fast mixing properties of a stopped-flow apparatus which initializes a biochemical reaction within milliseconds. With KITA, we analyzed the collective water dynamics during substrate hydrolyses by a human matrix-metalloproteinase. In addition, we studied the reorganization and electrostatic changes at the catalytic zinc-ion from the enzyme active site and performed molecular dynamics simulations of the enzyme-substrate-water system. Our results revealed a systematic gradient of water network motions: From the active site to the bulk water hydrogen bond dynamics increased from 7 ps (active site) to 1ps (bulk water) prior to substrate binding and hydrolysis. The approaching substrate perturbs the dynamic water gradient resulting in an overshoot of KITA signal which then relaxes back during onset of substrate hydrolyses. Our findings suggest that collective water dynamics may contribute to effective substrate binding to enzyme active sites and could be induced by the charge of the catalytic zinc-ion residing at the active site.

  3. Influence of the water content on the diffusion coefficients of Li+ and water across naphthalenic based copolyimide cation-exchange membranes.

    PubMed

    Garrido, Leoncio; Pozuelo, Javier; López-González, Mar; Yan, Gengwei; Fang, Jianhua; Riande, Evaristo

    2012-09-27

    The transport of lithium ions in cation-exchange membranes based on sulfonated copolyimide membranes is reported. Diffusion coefficients of lithium are estimated as a function of the water content in membranes by using pulsed field gradient (PFG) NMR and electrical conductivity techniques. It is found that the lithium transport slightly decreases with the diminution of water for membranes with water content lying in the range 14 < ? < 26.5, where ? is the number of molecules of water per fixed sulfonate group. For ? < 14, the value of the diffusion coefficient of lithium experiences a sharp decay with the reduction of water in the membranes. The dependence of the diffusion of lithium on the humidity of the membranes calculated from conductivity data using Nernst-Planck type equations follows a trend similar to that observed by NMR. The possible explanation of the fact that the Haven ratio is higher than the unit is discussed. The diffusion of water estimated by (1)H PFG-NMR in membranes neutralized with lithium decreases as ? decreases, but the drop is sharper in the region where the decrease of the diffusion of protons of water also undergoes considerable reduction. The diffusion of lithium ions computed by full molecular dynamics is similar to that estimated by NMR. However, for membranes with medium and low concentration of water, steady state conditions are not reached in the computations and the diffusion coefficients obtained by MD simulation techniques are overestimated. The curves depicting the variation of the diffusion coefficient of water estimated by NMR and full dynamics follow parallel trends, though the values of the diffusion coefficient in the latter case are somewhat higher. The WAXS diffractograms of fully hydrated membranes exhibit the ionomer peak at q = 2.8 nm(-1), the peak being shifted to higher q as the water content of the membranes decreases. The diffractograms present additional peaks at higher q, common to wet and dry membranes, but the peaks are better resolved in the wet membranes. The ionomer peak is not detected in the diffractograms of dry membranes. PMID:22957828

  4. Evaluation of Water Stress Coefficient Methods to Estimate Actual Corn Evapotranspiration in Colorado

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abstract for Kullberg Hydrology Days: Abstract. Increased competition for water resources is placing pressure on the agricultural sector to remain profitable while reducing water use. Remote sensing techniques have been developed to monitor crop water stress and produce information for evapotranspi...

  5. Absorption of water and solute from glucose-electrolyte solutions in the human jejunum: effect of citrate or betaine.

    PubMed

    Leiper, J B; Maughan, R J

    1989-11-01

    The inclusion in oral rehydration solutions of solutes that are actively co-transported with sodium has been suggested as a means of increasing the effect of glucose on water absorption by the small intestine. Using a modified perfusion system we have examined water and solute absorption in the normal human intestine from two effervescent glucose-electrolyte solutions, containing either citrate or betaine hydrochloride, and compared the absorption rates with those from a commonly used bicarbonate-containing oral rehydration solution. Absorption of citrate (355 +/- 87 mumol/cm/h) and betaine (313 +/- 125 mumol/cm/h) occurred from the respective solutions. The inclusion of 46 mmol/l citrate or 36 mmol/l betaine in effervescent oral rehydration solutions had no effect on water or solute absorption. PMID:2595270

  6. Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 °C

    NASA Astrophysics Data System (ADS)

    Jay-Gerin, Jean-Paul; Lin, Mingzhang; Katsumura, Yosuke; He, Hui; Muroya, Yusa; Meesungnoen, Jintana

    2008-09-01

    The optical absorption spectra of the hydrated electron (eaq-) in supercritical (heavy) water (SCW) are measured by electron pulse radiolysis techniques as a function of water density at three temperatures of 380, 390, and 400 °C, and over the density range of ˜0.2-0.65 g/cm3. In agreement with previous work, the position of the eaq- absorption maximum (EAmax) is found to shift slightly to lower energies (spectral "redshift") with decreasing density. A comparison of the present EAmax-density data with other measurements already reported in the literature in subcritical (350 °C) and supercritical (375 °C) water reveals that at a fixed pressure, EAmax decreases monotonically with increasing temperature in passing through the phase transition at tc. By contrast, at constant density, EAmax exhibits a minimum as the water passes above the critical point into SCW. These behaviors are explained in terms of simple microscopic arguments based on the crucial role played by local density and configurational fluctuations (associated with criticality) in providing pre-existing polymeric clusters, which act as trapping sites for electrons.

  7. Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols

    NASA Technical Reports Server (NTRS)

    Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.; Ponsardin, Patrick; Hueser, Alene W.

    1994-01-01

    An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and greater than 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less than 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

  8. Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols.

    PubMed

    Higdon, N S; Browell, E V; Ponsardin, P; Grossmann, B E; Butler, C F; Chyba, T H; Mayo, M N; Allen, R J; Heuser, A W; Grant, W B; Ismail, S; Mayor, S D; Carter, A F

    1994-09-20

    An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H(2)O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and > 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H(2)O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H(2)O absorption-line parameters were perfo med to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H(2)O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H(2)O radiosondes. The H(2)O distributions measured with the DIAL system differed by ? 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions. PMID:20941181

  9. Measurements of near-IR water vapor absorption at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Rieker, G. B.; Liu, X.; Li, H.; Jeffries, J. B.; Hanson, R. K.

    2007-03-01

    Tunable diode lasers (TDLs) are used to measure high resolution (0.1 cm-1), near-infrared (NIR) water vapor absorption spectra at 700 K and pressures up to 30 atm within a high-pressure and -temperature optical cell in a high-uniformity tube furnace. Both direct absorption and wavelength modulation with second harmonic detection (WMS-2f) spectra are obtained for 6 cm-1 regions near 7204 cm-1 and 7435 cm-1. Direct absorption measurements at 700 K and 10 atm are compared with simulations using spectral parameters from HITRAN and a hybrid database combining HITRAN with measured spectral constants for transitions in the two target spectral regions. The hybrid database reduces RMS error between the simulation and the measurements by 45% for the 7204 cm-1 region and 28% for the 7435 cm-1 region. At pressures above 10 atm, the breakdown of the impact approximation inherent to the Lorentzian line shape model becomes apparent in the direct absorption spectra, and measured results are in agreement with model results and trends at elevated temperatures reported in the literature. The wavelength-modulation spectra are shown to be less affected by the breakdown of the impact approximation and measurements agree well with the hybrid database predictions to higher pressures (30 atm).

  10. ICG 2000 Amsterdam Glass in the new Millennium Absorption Spectra of Iron and Water in Silicate Glasses

    E-print Network

    Glebov, Leon

    ]. This glass composition is similar to the standard float glass used in the glass industry, mol.%: 13Na2O-10Ca as sodium nitrate or oxygen was bubbled through the liquid glass in the furnace. Absorption spectra wereICG 2000 Amsterdam ­ Glass in the new Millennium Absorption Spectra of Iron and Water in Silicate

  11. Mass transfer of SCWO processes: Molecular diffusion and mass transfer coefficients of inorganic nitrate species in sub- and supercritical water

    SciTech Connect

    Goemans, M.G.E.; Gloyna, E.F. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering; Buelow, S.J. [Los Alamos National Lab., NM (United States)

    1996-04-01

    Molecular diffusion coefficients of lithium-, sodium-, potassium-, cesium-, calcium-, and strontium nitrate in subcritical water were determined by analysis of Taylor dispersion profiles. Pressures ranged from 300 to 500 bar at temperatures ranging from 25{degrees}C to 300{degrees}C. The reported diffusion values were determined at infinite dilution. Molecular diffusion coefficients were 10 to 20 times faster in near-critical subcritical water than in water at ambient temperature and pressure (ATP). These findings implied that the diffusion rates were more liquid like than they were gas like, hence experimental results were correlated with diffusion models for liquids. The subcritical diffusion data presented in this work, and supercritical diffusion results published elsewhere were correlated with hydrodynamic diffusion equations. Both the Wilke-Chang correlation and the Stokes-Einstein equation yielded predictions within 10% of the experimental results if the structure of the diffusing species could be estimated. The effect of the increased diffusion rates on mass transfer rates in supercritical water oxidation applications was quantified, with emphasis on heterogeneous oxidation processes. This study and results published elsewhere showed that diffusion limited conditions are much more likely to be encountered in SCWO processes than commonly acknowledged.

  12. Coefficients of caffeine distribution in aliphatic alcohol-ammonium sulfate-water systems

    NASA Astrophysics Data System (ADS)

    Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

    2012-11-01

    The extraction of caffeine with aliphatic alcohols C3-C9 from aqueous solutions in the presence of a salting-out agent (ammonium sulfate) is studied. Quantitative characteristics of extraction are calculated: the distribution coefficients ( D) and the degree of recovery ( R, %). Relations are found between log D of caffeine and the length of the hydrocarbon radical in the alcohol molecule, along with certain physicochemical properties of the extragents.

  13. Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

    1991-01-01

    Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

  14. WATER ABSORPTION FROM GAS VERY NEAR THE MASSIVE PROTOSTAR AFGL 2136 IRS 1

    SciTech Connect

    Indriolo, Nick; Neufeld, D. A. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Seifahrt, A. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Richter, M. J. [Department of Physics, University of California Davis, Davis, CA 95616 (United States)

    2013-10-10

    We present ground-based observations of the ?{sub 1} and ?{sub 3} fundamental bands of H{sub 2}O toward the massive protostar AFGL 2136 IRS 1, identifying absorption features due to 47 different ro-vibrational transitions between 2.468 ?m and 2.561 ?m. Analysis of these features indicates the absorption arises in warm (T = 506 ± 25 K), very dense (n(H{sub 2}) > 5 × 10{sup 9} cm{sup –3}) gas, suggesting an origin close to the central protostar. The total column density of warm water is estimated to be N(H{sub 2}O) = (1.02 ± 0.02) × 10{sup 19} cm{sup –2}, giving a relative abundance of N(H{sub 2}O)/N(H{sub 2}) ? 10{sup –4}. Our study represents the first extensive use of water vapor absorption lines in the near infrared, and demonstrates the utility of such observations in deriving physical parameters.

  15. Atmospheric water vapor differential absorption measurements on vertical paths with a CO2 lidar.

    PubMed

    Baker, P W

    1983-08-01

    Ground based vertical path differential absorption measurements were obtained up to a height of 1.5 km with a CO2 lidar transmitting alternatively on the R(20) (10.247-microm) and R(18) (10.260-microm) lines during daylight in conditions of both strong and weak temperature inversions. The differential absorption between these lines for typical middle latitude lower atmosphere water vapor concentrations appears to be well suited to this type of measurement as the power loss on the more absorbed backscattered line [R(20)] is not too great as to unduly restrict the operating range, while the power differential is still sufficiently large to be readily measureable. In one set of measurements a strong temperature inversion at a height of 1 km resulted in a rapid vertical lapse in aerosol concentration with a consequent loss of SNR on the returns and severe distortion to the differential absorption profiles at this level. Water vapor profiles were derived from all measurements except in the region of the strong temperature inversion where the atmospheric backscattering cross section decayed rapidly. Reasonable results were obtained through the weak inversion region. The measurement capability of the lidar was found to be restricted by the length of the laser pulse tail and an inadequate signal-to-noise performance in regions of strong temperature inversions due to the associated decreases in aerosol concentration. PMID:18196122

  16. Surface Arsenic Speciation of a Drinking-Water Treatment Residual Using X-Ray Absorption Spectroscopy

    SciTech Connect

    Makris, K.C.; Sarkar, D.; Parsons, J.G.; Datta, R.; Gardea-Torresdey, J.L.

    2009-06-03

    Drinking-water treatment residuals (WTRs) present a low-cost geosorbent for As-contaminated waters and soils. Previous work has demonstrated the high affinity of WTRs for As, but data pertaining to the stability of sorbed As is missing. Sorption/desorption and X-ray absorption spectroscopy (XAS), both XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) studies, were combined to determine the stability of As sorbed by an Fe-based WTR. Arsenic(V) and As(III) sorption kinetics were biphasic in nature, sorbing <90% of the initial added As (15,000 mg kg{sup -1}) after 48 h of reaction. Subsequent desorption experiments with a high P load (7500 mg kg{sup -1}) showed negligible As desorption for both As species, approximately <3.5% of sorbed As; the small amount of desorbed As was attributed to the abundance of sorption sites. XANES data showed that sorption kinetics for either As(III) or As(V) initially added to solution had no effect on the sorbed As oxidation state. EXAFS spectroscopy suggested that As added either as As(III) or as As(V) formed inner-sphere mononuclear, bidentate complexes, suggesting the stability of the sorbed As, which was further corroborated by the minimum As desorption from the Fe-WTR.

  17. Water Absorption from Gas Very near the Massive Protostar AFGL 2136 IRS 1

    NASA Astrophysics Data System (ADS)

    Indriolo, Nick; Neufeld, D. A.; Seifahrt, A.; Richter, M. J.

    2013-10-01

    We present ground-based observations of the ?1 and ?3 fundamental bands of H2O toward the massive protostar AFGL 2136 IRS 1, identifying absorption features due to 47 different ro-vibrational transitions between 2.468 ?m and 2.561 ?m. Analysis of these features indicates the absorption arises in warm (T = 506 ± 25 K), very dense (n(H2) > 5 × 109 cm-3) gas, suggesting an origin close to the central protostar. The total column density of warm water is estimated to be N(H2O) = (1.02 ± 0.02) × 1019 cm-2, giving a relative abundance of N(H2O)/N(H2) ? 10-4. Our study represents the first extensive use of water vapor absorption lines in the near infrared, and demonstrates the utility of such observations in deriving physical parameters. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile as part of program 089.C-0321

  18. Prediction of Mass Absorption of Ammonia Vapor into Ammonia Water Solution

    NASA Astrophysics Data System (ADS)

    Monde, Masanori; Mustafa, Hatem

    Mass absorption rate of ammonia vapor into ammonia water solution is investigated experimentally, by feeding a superheated ammonia vapor into a test cell to be absorbed into stagnant pool of ammonia water solution with an initial mass concentration of Ci = 0.0 to 0.63 kg/kg. The flowing of the ammonia vapor is due to a pressure difference of ?P = 50 to 300 kPa between the ammonia vapor cylinder and the pressure of the test cell. The main objectives are, to investigate the effect of initial pressure difference on the absorption rate of ammonia vapor and to develop an equation which predicts the total absorbed mass of ammonia with initial pressure difference, initial concentration and time. The experiment shows that the total absorbed mass of ammonia linearly increases with increasing initial pressure difference. A correlation can be proposed to yield the total absorbed mass of ammonia measured in the experiment. In addition, the absorbed mass at no pressure difference, namely free absorption, could be estimated from the absorbed mass at initial pressure difference.

  19. Absorption spectrum of deuterated water vapor enriched by 18O between 6000 and 9200 cm-1

    NASA Astrophysics Data System (ADS)

    Mikhailenko, S. N.; Naumenko, O. V.; Nikitin, A. V.; Vasilenko, I. A.; Liu, A.-W.; Song, K.-F.; Ni, H.-Y.; Hu, S.-M.

    2012-06-01

    The absorption spectrum of water vapor enriched by deuterium and oxygen-18 is analyzed in the 6000-9200 cm-1 region. The spectrum has been recorded at room temperature with a Bruker IFS 120 h Fourier transform spectrometer. More than 14,000 absorption lines were measured in the recorded spectrum. The vibration-rotation assignments were performed on the basis of previously published experimental energies and of variational calculations. Nine water species (H216O, HD16O, D216O, H218O, HD18O, D218O, H217O, HD17O and D217O) were found to contribute to the observed absorption. More than 3600 lines of 19 vibrational bands of D218O and about 4700 lines of 16 bands of HD18O with J as high as 19 and Ka as high as 11 were assigned. The main part of the HD18O and D218O lines and all lines of HD17O and D217O were observed in the laboratory for the first time. The obtained vibration-rotation energy levels are compared with previous experimental studies and the results of variational calculations.

  20. Multiplexed Selective Detection and Identification of TCE and Xylene in Water by On-Chip Absorption Spectroscopy

    E-print Network

    Chen, Ray

    Multiplexed Selective Detection and Identification of TCE and Xylene in Water by On-Chip Absorption spectroscopy. The signature of Trichloroethylene(TCE) and xylene in water enable multiplexed detection on one Volatile Organic Compounds (VOCs) in liquid and gaseous phases to detect xylene in water and methane

  1. Using water quality variables to predict light attenuation coefficient: case study in Shihmen Reservoir

    Microsoft Academic Search

    Wen-Cheng Liu; Ray-Shyan Wu; Edward Ming-Yang Wu; Yu-Pei Chang; Wei-Bo Chen

    2010-01-01

    The amount of photosynthetically active radiation (PAR) in the water column is of fundamental importance in determining the\\u000a growth of aquatic plant and aquatic primary production. Light attenuation in aquatic ecosystems has important ecological implication\\u000a and water quality applications. In the present study, the light attenuation through the water column in the Shihmen Reservoir,\\u000a Taiwan was measured. A light attenuation

  2. Evaluation of three models for predicting newly determined octanol-water partition coefficients and mechanisms for substituted aromatic compounds.

    PubMed

    Wu, Chunde; Wei, Dongbin; Liu, Xinhui; Lin, Zhifen; Wang, Liansheng

    2002-01-01

    Octanol-water partition coefficients (K(ow)) of 27 substituted aromatic compounds, including polyhalogenated aromatics, were determined. A molecular connectivity index (MCI), a theoretical linear solvation energy relationship, and a quantum chemical method were applied to model the property and study the partition mechanism. The multiple correction coefficients (r2(adj)) (> or = 0.870) and the standard errors (< or = 0.33) for log K(ow) indicated that the models were successful. Comparing the three models, the MCI method (including the nondisperse force factor) was the most satisfactory. However, the quantum chemical model based on the potential of the negative atomic charge, total energy, and molecular weight revealed that the molecular bulk properties and electrostatic interaction were the most important factors influencing the partition process. PMID:12150246

  3. Experimental Study of Diffusion Coefficients of Water through the Collagen: Apatite Porosity in Human Trabecular Bone Tissue

    PubMed Central

    Bini, Fabiano; Marinozzi, Andrea

    2014-01-01

    We firstly measured the swelling of single trabeculae from human femur heads during water imbibition. Since the swelling is caused by water diffusing from external surfaces to the core of the sample, by measuring the sample swelling over time, we obtained direct information about the transport of fluids through the intimate constituents of bone, where the mineralization process takes place. We developed an apparatus to measure the free expansion of the tissue during the imbibition. In particular, we measured the swelling along three natural axes (length L, width W, and thickness T) of plate-like trabeculae. For this aim, we developed a 3D analytical model of the water uptake by the sample that was performed according to Fickian transport mechanism. The results were then utilized to predict the swelling over time along the three sample directions (L, W, T) and the apparent diffusion coefficients DT, DW, and DL. PMID:24967405

  4. Monochromatic calculations of atmospheric radiative transfer due to molecular line absorption

    Microsoft Academic Search

    M.-D. Chou; Louis Kouvaris

    1986-01-01

    Sensitivity studies related to the effects of line cutoff, spectral resolution, and temperature and pressure interpolations in radiative transfer have been performed so that a data set of absorption coefficients for water vapor, CO2, and O3 may be created efficiently. Results show that computations of absorption coefficients are affected only slightly by cutting a line off at a wave number

  5. Performance of Generator of Absorption Refrigerating Machine Powered by Hot Water

    NASA Astrophysics Data System (ADS)

    Kunugi, Yoshifumi; Usui, Sanpei; Ouchi, Tomihisa; Fukuda, Tamio

    For 70 kW generator of absorption refrigerating machine powered by the hot water, lifted liquid rate of the bubble lift pump has a maximum value at some vapor flow rate of refrigerant and hot water inlet temperature. This is in agreement with results of small size bubble lift pump. Maximum lifted liquid rate G0 is correlated by the equation G0 = 5, 000?1.5, where ? is the degree of submergence. In this case, diameter of pump tube was 41.6mm, and length of it were 1,300 and 1,500mm. The range of hot water inlet temperature was 78 - 100°C. Multitube heat flux of first generator is about two times that of second generator at the same superheat.

  6. Microwave-assisted synthesis of water-soluble, fluorescent gold nanoclusters capped with small organic molecules and a revealing fluorescence and X-ray absorption study

    NASA Astrophysics Data System (ADS)

    Helmbrecht, C.; Lützenkirchen-Hecht, D.; Frank, W.

    2015-03-01

    Colourless solutions of blue light-emitting, water-soluble gold nanoclusters (AuNC) were synthesized from gold colloids under microwave irradiation using small organic molecules as ligands. Stabilized by 1,3,5-triaza-7-phosphaadamantane (TPA) or l-glutamine (GLU), fluorescence quantum yields up to 5% were obtained. AuNC are considered to be very promising for biological labelling, optoelectronic devices and light-emitting materials but the structure-property relationships have still not been fully clarified. To expand the knowledge about the AuNC apart from their fluorescent properties they were studied by X-ray absorption spectroscopy elucidating the oxidation state of the nanoclusters' gold atoms. Based on curve fitting of the XANES spectra in comparison to several gold references, optically transparent fluorescent AuNC are predicted to be ligand-stabilized Au5+ species. Additionally, their near edge structure compared with analogous results of polynuclear clusters known from the literature discloses an increasing intensity of the feature close to the absorption edge with decreasing cluster size. As a result, a linear relationship between the cluster size and the X-ray absorption coefficient can be established for the first time.Colourless solutions of blue light-emitting, water-soluble gold nanoclusters (AuNC) were synthesized from gold colloids under microwave irradiation using small organic molecules as ligands. Stabilized by 1,3,5-triaza-7-phosphaadamantane (TPA) or l-glutamine (GLU), fluorescence quantum yields up to 5% were obtained. AuNC are considered to be very promising for biological labelling, optoelectronic devices and light-emitting materials but the structure-property relationships have still not been fully clarified. To expand the knowledge about the AuNC apart from their fluorescent properties they were studied by X-ray absorption spectroscopy elucidating the oxidation state of the nanoclusters' gold atoms. Based on curve fitting of the XANES spectra in comparison to several gold references, optically transparent fluorescent AuNC are predicted to be ligand-stabilized Au5+ species. Additionally, their near edge structure compared with analogous results of polynuclear clusters known from the literature discloses an increasing intensity of the feature close to the absorption edge with decreasing cluster size. As a result, a linear relationship between the cluster size and the X-ray absorption coefficient can be established for the first time. Electronic supplementary information (ESI) available: The deconvoluted reference spectra are given in ESI Fig. 1-9. See DOI: 10.1039/c4nr07051h

  7. Cloud point extraction-flame atomic absorption spectrometry method for preconcentration and determination of trace cadmium in water samples.

    PubMed

    Ning, Jinyan; Jiao, Yang; Zhao, Jiao; Meng, Lifen; Yang, Yaling

    2014-01-01

    A method based on cloud point extraction (CPE) separation/preconcentration of trace cadmium (Cd) as a prior step to its determination by flame atomic absorption spectrometry has been developed. Cadmium reacted with 8-hydroxyquinoline to form hydrophobic chelates, which were extracted into the micelles of nonionic surfactant oligoethylene glycol monoalkyl ether (Genapol X-080) in an alkaline medium. Octanol was used to depress the cloud point of Genapol X-080 in the extraction process. The chemical variables that affect the CPE, such as pH of complexation reaction, amount of chelating agent, Genapol X-080 and octanol were evaluated and optimized. Under optimized conditions, linearity was obeyed in the range of 10-500 ?g/L, with the correlation coefficient of 0.9993. For 5 mL of sample solution, the enhancement factor was about 20. The limit of detection and limit of quantification of the method were 0.21 and 0.63 ?g/L, respectively. The relative standard deviations (n = 6) was 3.2% for a solution containing 100 ?g/L of Cd. The accuracy of the preconcentration system was evaluated by recovery measurements on spiked water samples. Recoveries of spiked samples varied in the range of 94.1-103.8%. PMID:25116488

  8. Derivation of total diffuse attenuation coefficient from water column temperature data and meteorological water surface fluxes: A simple management tool

    Microsoft Academic Search

    Sri Adiyanti; Jörg Imberger

    2007-01-01

    The total diffuse attenuation coefficient of Photosynthetically Available Radiation (Kd(PAR)) is derived by optimising the solution of a surface layer model to match temperature profiles measured with a precision thermistor chain; a non?linear least?squares Levenberg?Marquardt scheme is applied to optimize Kd(PAR). The method was validated in Lake Kinneret (Israel) over 10 days in summer to early winter 2001, Valle de

  9. On-line preconcentration of cobalt in drinking water using a minicolumn packed with activated carbon coupled to electrothermal atomic absorption spectrometric determination

    NASA Astrophysics Data System (ADS)

    Cerutti, Soledad; Moyano, Susana; Gásquez, José A.; Stripeikis, Jorge; Olsina, Roberto A.; Martinez, Luis D.

    2003-11-01

    An on-line flow injection preconcentration-electrothermal atomic absorption spectrometry method is developed for trace determination of cobalt in drinking water samples by sorption on a conical minicolumn packed with activated carbon at pH 9.5. The cobalt was eluted from the minicolumn with 10% (v/v) nitric acid. An enrichment factor of 190-fold for a sample volume of 10 ml was obtained. The detection limit (DL) value for the preconcentration method proposed was 5 ng l -1. The precision for 10 replicate determinations at the 50 ng l -1 Co level was 4.7% relative standard deviation. The calibration graph using the preconcentration system for cobalt was linear with a correlation coefficient of 0.9993 at levels near the DLs up to at least 0.35 ?g l -1. The method was successfully applied to the determination of cobalt in drinking water samples.

  10. High-resolution atmospheric water vapor measurements with a scanning differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Späth, F.; Behrendt, A.; Muppa, S. K.; Metzendorf, S.; Riede, A.; Wulfmeyer, V.

    2014-11-01

    The scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) is presented. The UHOH DIAL is equipped with an injection-seeded frequency-stabilized high-power Ti:sapphire laser operated at 818 nm with a repetition rate of 250 Hz. A scanning transceiver unit with a 80 cm primary mirror receives the atmospheric backscatter signals. The system is capable of water vapor measurements with temporal resolutions of a few seconds and a range resolution between 30 and 300 m at daytime. It allows to investigate surface-vegetation-atmosphere exchange processes with high resolution. In this paper, we present the design of the instrument and illustrate its performance with recent water vapor measurements taken in Stuttgart-Hohenheim and in the frame of the HD(CP)2 Observational Prototype Experiment (HOPE). HOPE was located near research center Jülich, in western Germany, in spring 2013 as part of the project "High Definition of Clouds and Precipitation for advancing Climate Prediction" (HD(CP)2). Scanning measurements reveal the 3-dimensional structures of the water vapor field. The influence of uncertainties within the calculation of the absorption cross-section at wavelengths around 818 nm for the WV retrieval is discussed. Radiosonde intercomparisons show a very small bias between the instruments of only (-0.04 ± 0.11) g m-3 or (-1.0 ± 2.3) % in the height range of 0.5 to 3 km.

  11. Microclimate in ski boots--temperature, relative humidity, and water absorption.

    PubMed

    Hofer, Patrick; Hasler, Michael; Fauland, Gulnara; Bechtold, Thomas; Nachbauer, Werner

    2014-05-01

    Ski boot quality is determined by mechanical properties and comfort. Comfort is strongly affected by cold feet. The purpose of this study was to determine the microclimate in ski boots. Climate chamber tests with five male subjects and field tests with two male subjects were conducted. Temperature and relative humidity were measured using four sensors placed on the foot and one on the liner. Absorbed water in liners and socks was measured with a precision balance. The subjects gave subjective ratings for comfort. The toe sensor temperature dropped below 20 °C at an ambient temperature of 0 °C, -10 °C, and -20 °C. Relative humidity values at the foot were as high as 78% in the climate chamber and 93% in the field. Water absorption in socks and liners ranged from 4 to 10 g in the climate chamber and 19 to 45.5 g in the field. The results reveal the importance of keeping the feet and in particular the toes warm during skiing. One possible improvement may be to construct the liner so that sweat and melted snow are kept as far away as possible from the foot. Liner material with high water absorption capacity and hydrophobic socks were suggested to prevent wet feet. PMID:23932378

  12. Absorption of crystalline water ice in the far infrared at different temperatures

    NASA Astrophysics Data System (ADS)

    Reinert, C.; Mutschke, H.; Krivov, A. V.; Löhne, T.; Mohr, P.

    2015-01-01

    The optical properties of ice in the far infrared are important for models of protoplanetary and debris disks. In this report, we derive a new set of data for the absorption (represented by the imaginary part of the refractive index ?) of crystalline water ice in this spectral range. The study includes a detailed inspection of the temperature dependence, which has not been conducted in such detail before. We measured the transmission of three ice layers with different thicknesses at temperatures ? = 10...250 K and present data at wavelengths ? = 80...625 ?m. We found a change in the spectral dependence of ? at a wavelength of 175 ± 6 ?m. At shorter wavelengths, ? exhibits a constant flat slope and no significant temperature dependence. Long-ward of that wavelength, the slope gets steeper and has a clear, approximately linear temperature dependence. This change in behaviour is probably caused by a characteristic absorption band of water ice. The measured data were fitted by a power-law model that analytically describes the absorption behaviour at an arbitrary temperature. This model can readily be applied to any object of interest, for instance a protoplanetary or debris disk. To illustrate how the model works, we simulated the spectral energy distribution (SED) of the resolved, large debris disk around the nearby solar-type star HD 207129. Replacing our ice model by another, commonly used data set for water ice results in a different SED slope at longer wavelengths. This leads to changes in the characteristic model parameters of the disk, such as the inferred particle size distribution, and affects the interpretation of the underlying collisional physics of the disk.

  13. QSPR modelling of the octanol\\/water partition coefficient of organometallic substances by optimal SMILES-based descriptors

    Microsoft Academic Search

    Andrey A. Toropov; Alla P. Toropova; Emilio Benfenati

    2009-01-01

    Usually, QSPR is not used to model organometallic compounds. We have modeled the octanol\\/water partition coefficient for organometallic\\u000a compounds of Na, K, Ca, Cu, Fe, Zn, Ni, As, and Hg by optimal descriptors calculated with simplified molecular input line\\u000a entry system (SMILES) notations. The best model is characterized by the following statistics: n=54, r2=0.9807, s=0.677, F=2636 (training set); n=26, r2=0.9693,

  14. Aqueous Solubility, n Octanol–Water Partition Coefficient, and Sorption of Five Selective Serotonin Reuptake Inhibitors to Sediments and Soils

    Microsoft Academic Search

    Jeong-Wook Kwon; Kevin L. Armbrust

    2008-01-01

    Aqueous solubilities (S\\u000a w) and n-octanol–water partition coefficients (K\\u000a ow) of five selective serotonin reuptake inhibitors (SSRIs) were measured and sorption to two sediments and three soils with\\u000a organic matter contents ranging from 0.16% to 1.77% and pH ranging between 5.0 and 7.8 was investigated using a batch equilibrium\\u000a method. SSRIs had high S\\u000a w (3,022–15,460 mg\\/l) and relatively low log

  15. Rapid Estimation of Octanol–Water Partition Coefficient for Triazole Fungicides by MEKC with Sodium Deoxycholate as Surfactant

    Microsoft Academic Search

    Wan Aini Wan Ibrahim; Dadan Hermawan; Mohamed Noor Hasan; Hassan Y. Aboul Enein; M. Marsin Sanagi

    2008-01-01

    A rapid estimation of octanol–water partition coefficient (log P\\u000a ow) was developed for triazole fungicides by micellar electrokinetic chromatography (MEKC). Five standard compounds with known\\u000a log P\\u000a ow values from 2.9 to 4.3 (cyproconazole, bromuconazole, epoxiconazole, bitertanol and difenoconazole) were used for constructing\\u000a the calibration curve of the log P\\u000a ow against the MEKC retention factor, log k. A linear

  16. The effect of cosolutes on the aqueous solubilities and octanol\\/water partition coefficients of selected polychlorinated biphenyl congeners

    Microsoft Academic Search

    An Li; William J. Doucette

    1993-01-01

    Aqueous solubilities (S) and 1-octanol\\/water partition coefficients (K[sub ow]) of four PCBs-- 4-chlorobiphenyl, 2,4,6-trichlorobiphenyl, 2,3,4,5-tetrachlorobiphenyl, and 2,2[prime],4,4[prime],6,6[prime]-hexachlorobiphenyl -- were determined both individually and in pairs, using a generator-column technique, to investigate the effect of cosolutes on S and K[sub ow]. No statistical differences between S and K[sub ow] measured individually and in pairs were observed for the four PCBs in

  17. Simulation model of a single-stage lithium bromide-water absorption cooling unit

    NASA Technical Reports Server (NTRS)

    Miao, D.

    1978-01-01

    A computer model of a LiBr-H2O single-stage absorption machine was developed. The model, utilizing a given set of design data such as water-flow rates and inlet or outlet temperatures of these flow rates but without knowing the interior characteristics of the machine (heat transfer rates and surface areas), can be used to predict or simulate off-design performance. Results from 130 off-design cases for a given commercial machine agree with the published data within 2 percent.

  18. Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV, 1992

    SciTech Connect

    Higgins, P.D.; Attix, F.H.; Hubbell, J.H.; Seltzer, S.M.; Berger, M.J.

    1992-03-01

    Mass energy-transfer and mass energy-absorption coefficients are tabulated in units of sq cm/g for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general dosimetric interest. Cross sections for photo-effect, incoherent scattering, pair and triplet production are those compiled or generated by the National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards). Corrections are included for in-flight positron annihilation, previously not applied in NIST calculations for energies above 10 MeV. Agreement with recently published data is good for energies above 1 MeV, but the authors find differences in mass energy-absorption coefficients in the low energy region of as much as 4% compared with the last NIST compilation, and as much as 9% when compared with other recent compilations.

  19. Evidence for direct water absorption by shallow-rooted desert plants in desert-oasis ecotone, Northwest China

    NASA Astrophysics Data System (ADS)

    Fang, Jing

    2014-05-01

    Besides the absorption by roots from the soil substrate, it has long been known that plants exhibit alternative water-absorption strategies, particularly in drought-prone environments. For many tropical epiphytic orchids, air moisture can be absorbed directly by aerial roots. Some conifers are also found to utilize air moisture by foliar absorption during the summer fog season. However, few studies have been carried out on the atmospheric water vapor absorption by shallow-rooted desert plants. We conducted experiments in desert-oasis ecotone and investigated the effects of dew absorbed by three kinds of shallow-rooted seedlings on net photosynthesis rate, as well as on other water relations variables. Three kinds of typical shallow-rooted desert species (Bassia dasyphylla, Salsola collina and Corispermum declinatum) have been chosen and potted. Each species were subjected to contrasting watering regimes (normal and deficient) and different air moisture conditions (having dew and having no dew) for 10 weeks. Net photosynthesis rate was measured on six occasions during the study. Other water relations variables (midday shoot water potential, relative water content, stomatal conductance) were also measured. Under the dew conditions, average net photosynthesis rate, shoot water potential, leaf relative water content and stomatal conductance increased, with greater responses observed for plants subjected to a deficient watering regime than for well-watered plants. These results indicated dew occurred in arid region could be utilized through foliar absorption by some shallow-rooted plants, and for the shallow-rooted plants, the presence of dew could significantly relieve the deficit of water in water-stressed regime.

  20. Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV, 1992

    Microsoft Academic Search

    P. D. Higgins; F. H. Attix; J. H. Hubbell; S. M. Seltzer; M. J. Berger

    1992-01-01

    Mass energy-transfer and mass energy-absorption coefficients are tabulated in units of sq cm\\/g for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general desimetric interest. Cross sections for photo-effects, incoherent scattering, and pair and triplet production are those compiled or generated by the National Institute of Standards and

  1. Significance of active ion transport in transalveolar water absorption: a study on isolated rat lung.

    PubMed Central

    Basset, G; Crone, C; Saumon, G

    1987-01-01

    1. Experiments were performed on isolated rat lungs perfused with Ringer solutions containing red cells. The goal was to clarify the role of active transport of Na+ for the absorption of fluid across the alveolar membrane, and to characterize active and passive pathways. 2. Partially degassed lungs were filled with 5 ml of an isotonic Ringer solution containing 125I-labelled albumin in order to calculate the fluid movement, and 22Na+ or 36Cl- for measurement of ion fluxes. Passive non-electrolyte permeability was determined in all experiments using [3H]mannitol. 3. The average rate of fluid absorption in phosphate-buffered instillates was 134 nl/s (S.E., 18.5; n = 14). With ouabain (10(-4) M) in the perfusate the fluid absorption rate fell to 57 nl/s (S.E., 8.2; n = 18). Amiloride (10(-3)-10(-4) M) in the instillate reduced the absorption to 75 nl/s (S.E., 8.6; n = 16). These results show that fluid absorption depends on transcellular transport of Na+ and that alveolar epithelial cells have a Na+ entry system in the luminal membrane and a Na+-K+ pump in the abluminal membrane. 4. The transcellular ion transport operates in parallel with a paracellular, passive leak that allows mannitol to pass with a permeability surface area product of 1.2 X 10(-4) ml/s, corresponding to a permeability coefficient of 2.4 X 10(-8) cm/s, assuming an alveolar surface area of 5000 cm2. 5. The passive fluxes of Na+ were 9.4 pmol/(cm2s) (S.E., 1.3; n = 25) in the direction from alveoli to perfusate and 8.0 pmol/(cm2s) (S.E., 0.86; n = 6) from perfusate to plasma. The passive fluxes of Cl- in the two directions were not significantly different either. Thus the transalveolar electrical potential difference is too small to affect ion movements measurably. 6. The passive permeability to Na+ was 6.7 X 10(-8) cm/s and to Cl- was 10.2 X 10(-8) cm/s (alveolar surface area assumed to be 5000 cm2). The ratio of the permeabilities is close to the ratio of the diffusion coefficients in free solution, suggesting a neutral or weakly charged paracellular channel. 7. We conclude that the alveolar epithelium performs solute-coupled fluid transport from alveoli to plasma, and that it shows many features that are common to other fluid-transporting epithelia; with an approximate surface area of 100 m2 in humans it constitutes one of the largest epithelial surfaces in the body.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3656149

  2. Prediction of ecotoxicological behavior of chemicals: relationship between n-octanol/water partition coefficient and bioaccumulation of organic chemicals by alga Chlorella

    SciTech Connect

    Geyer, H.; Politzki, G.; Freitag, D.

    1984-01-01

    The bioaccumulation potential of organic chemicals by the green alga Chlorella fusca was determined. A quantitative relationship was found to exist between the lipophilicity (n-octanol/water partition coefficient) of the chemicals and the bioaccumulation factor.

  3. Bioaccumulation Patterns Of PCBs In A Temperate, Freshwater Food Web And Their Relationshop To The Octanol-Water Partition Coefficient (Presentation)

    EPA Science Inventory

    We investigated polychlorinated biphenyl (PCB) bioaccumulation relative to octanol-water partition coefficient (KOW) and organism tropic position (TP) at the Lake Hartwell Superfund site (South Carolina, USA). We measured PCBs (127 congeners) and stable isotopes (d...

  4. A molecular dynamics study on liquid 1-octanol. Part 3. Evaluating octanol/water partition coefficients of novel thrombin inhibitors via free-energy perturbations

    NASA Astrophysics Data System (ADS)

    Fernandes de Oliveira, César Augusto; Werneck Guimarães, Cristiano Ruch; de Mello, Heloisa; Echevarria, Aurea; de Alencastro, Ricardo Bicca

    Thrombin inhibition is an important strategy for the treatment of thrombotic and embolic disorders. Despite high in vitro affinity for the enzyme, synthetic thrombin inhibitors have limited oral bioavailability due to low intestinal permeability. In a previous work, we obtained the following order for thrombin binding by using molecular dynamics (MD) simulations and the finite difference thermodynamic integration (FDTI) method: p-(2-oxo-1-propyl)benzamidine (POPBz) > p-ethylbenzamidine (PEBz) > p-(1-propyl)benzamidine (PPBz) > p-methylbenzamidine (PMBz) > benzamidine (Bz). As the octanol/water partition coefficient (log Po/w) is a thermodynamic property that may be related to drug transfer across biological membranes, we now turn our attention to the calculation by the FDTI method of relative log Po/w for the benzamidine derivatives. To examine the reliability of the method, log Po/w values for Bz and PMBz were determined experimentally. Experimental log Po/w of -1.02 and -0.89 were obtained for Bz and PMBz, and theoretical log Po/w of -0.12, -0.01, and -1.00 were obtained for PEBz, PPBz, and POPBz. Thus, we improved the hydrophobicity of Bz by adding the methyl, ethyl, propyl, and 2-oxo-propyl groups, but further substitutions should be conducted to raise log Po/w above zero and into a region where reasonable oral absorption might be expected.

  5. The Accommodation Coefficient of Water Molecules on Ice: Results from Cirrus Cloud Experiments at the Aerosol Chamber AIDA

    NASA Astrophysics Data System (ADS)

    Skrotzki, J.; Connolly, P.; Niemand, M.; Saathoff, H.; Moehler, O.; Ebert, V.; Leisner, T.

    2010-12-01

    Cirrus clouds are pure ice clouds in the upper troposphere or lower stratosphere. One of the parameters governing the growth of ice crystals in these clouds is the accommodation coefficient of water molecules on ice. However, its magnitude is still uncertain to a large degree, since experimental results vary from below 0.01 up to unity depending on the design of the experiment and the examined ice growth process [1]. For the specific case of ice crystal growth in cirrus clouds, no previous experimental studies regarding the accommodation coefficient exist. Therefore, dedicated experiments were carried out at the cloud simulation chamber AIDA [2], examining the ice crystal growth for deposition nucleation in the temperature range from -75 °C to -40 °C. These experiments were evaluated with two different models, a simple one, which just incorporates kinetic and diffusive theory of ice crystal growth, and the more advanced and extended aerosol-cloud-precipitation interaction model (ACPIM) [3]. The outcome of these two models is compared to absolute in-situ humidity data measured within AIDA using extractive as well as open path diode laser hygrometers (TDLAS) [4]. For every experiment, this is done by varying the value of the accommodation coefficient within each model, in order to get best agreement with experimental data. The values obtained for the accommodation coefficient at different temperatures are presented and the overall uncertainties as well as the consistency between the two different models are discussed. [1] D. R. Heynes, N. J. Tro, and S. M. George, J. Phys. Chem. 1992, 96, 8502-8509 (1992) [2] O. Möhler et al., Atmos. Chem. Phys. 3, 211-223 (2003) [3] P. J. Connolly et al., Atmos. Chem. Phys. 9, 2805-2824 (2009) [4] D. W. Fahey et al., AquaVIT White Paper, avail. at https://aquavit.icg.kfa-juelich.de/AquaVit/AquaVitWiki

  6. Absorption spectra of liquid water and aqueous buffers between 0.3 and Department of Physics, University of California, Santa Barbara, California 93106

    E-print Network

    Xu, Jing

    Absorption spectra of liquid water and aqueous buffers between 0.3 and 3.72 THz Jing Xua Department-dependent terahertz absorption with attenuation lengths on the order of tens of micrometers. To access this spectral.5 THz, these studies provide a well- documented absorption spectrum for liquid water, at approxi- mately

  7. Differential Absorption Measurements of Atmospheric Water Vapor with a Coherent Lidar at 2050.532 nm

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Dharamsi, Amin; Davis, Richard E.; Petros, Mulugeta; McCarthy, John C.

    1999-01-01

    Wind and water vapor are two major factors driving the Earth's atmospheric circulation, and direct measurement of these factors is needed for better understanding of basic atmospheric science, weather forecasting, and climate studies. Coherent lidar has proved to be a valuable tool for Doppler profiling of wind fields, and differential absorption lidar (DIAL) has shown its effectiveness in profiling water vapor. These two lidar techniques are generally considered distinctly different, but this paper explores an experimental combination of the Doppler and DIAL techniques for measuring both wind and water vapor with an eye-safe wavelength based on a solid-state laser material. Researchers have analyzed and demonstrated coherent DIAL water vapor measurements at 10 micrometers wavelength based on CO2 lasers. The hope of the research presented here is that the 2 gm wavelength in a holmium or thulium-based laser may offer smaller packaging and more rugged operation that the CO2-based approach. Researchers have extensively modeled 2 um coherent lasers for water vapor profiling, but no published demonstration is known. Studies have also been made, and results published on the Doppler portion, of a Nd:YAG-based coherent DIAL operating at 1.12 micrometers. Eye-safety of the 1.12 micrometer wavelength may be a concern, whereas the longer 2 micrometer and 10 micrometer systems allow a high level of eyesafety.

  8. X-ray absorption signatures of the molecular environment in water and ice

    E-print Network

    Wei Chen; Xifan Wu; Roberto Car

    2009-09-21

    The x-ray absorption spectra of water and ice are calculated with a many-body approach for electron-hole excitations. The experimental features, including the small effects of temperature change in the liquid, are quantitatively reproduced from molecular configurations generated by ab-initio molecular dynamics. The spectral difference between the solid and the liquid is due to two major short range order effects. One, due to breaking of hydrogen bonds, enhances the pre-edge intensity in the liquid. The other, due to a non-bonded molecular fraction in the first coordination shell, affects the main spectral edge in the conversion of ice to water. This effect may not involve hydrogen bond breaking as shown by experiment in high-density amorphous ice.

  9. Multi-system repeatability and reproducibility of apparent diffusion coefficient measurement using an ice-water phantom

    PubMed Central

    Malyarenko, Dariya; Galbán, Craig J.; Londy, Frank J.; Meyer, Charles R.; Johnson, Timothy D.; Rehemtulla, Alnawaz; Ross, Brian D.; Chenevert, Thomas L.

    2012-01-01

    Purpose Quantitative quality control procedures were sought to evaluate technical variability in multi-center measurements of the diffusion coefficient of water as a prerequisite to use of the biomarker apparent diffusion coefficient (ADC) in multi-center clinical trials. Materials and Methods A uniform data acquisition protocol was developed and shared with 18 participating test sites along with a temperature-controlled diffusion phantom delivered to each site. Usable diffusion weighted imaging data of ice water at 5 b-values were collected on 35 clinical MRI systems from 3 vendors at 2 field strengths (1.5 and 3T) and analyzed at a central processing site. Results Standard deviation of bore-center ADCs measured across 35 scanners was <2%; error range: ?2% to +5% from literature value. Day-to-day repeatability of the measurements was within 4.5%. Intra-exam repeatability at the phantom center was within 1%. Excluding one outlier, inter-site reproducibility of ADC at magnet isocenter was within 3%, though variability increased for off-center measurements. Significant (>10%) vendor-specific and system-specific spatial non-uniformity ADC bias was detected for the off-center measurement that was consistent with gradient non-linearity. Conclusion Standardization of DWI protocol has improved reproducibility of ADC measurements and allowed identifying spatial ADC non-uniformity as a source of error in multi-site clinical studies. PMID:23023785

  10. Estimating the Octanol/Water Partition Coefficient for Aliphatic Organic Compounds Using Semi-Empirical Electrotopological Index

    PubMed Central

    Souza, Erica Silva; Zaramello, Laize; Kuhnen, Carlos Alberto; Junkes, Berenice da Silva; Yunes, Rosendo Augusto; Heinzen, Vilma Edite Fonseca

    2011-01-01

    A new possibility for estimating the octanol/water coefficient (log P) was investigated using only one descriptor, the semi-empirical electrotopological index (ISET). The predictability of four octanol/water partition coefficient (log P) calculation models was compared using a set of 131 aliphatic organic compounds from five different classes. Log P values were calculated employing atomic-contribution methods, as in the Ghose/Crippen approach and its later refinement, AlogP; using fragmental methods through the ClogP method; and employing an approach considering the whole molecule using topological indices with the MlogP method. The efficiency and the applicability of the ISET in terms of calculating log P were demonstrated through good statistical quality (r > 0.99; s < 0.18), high internal stability and good predictive ability for an external group of compounds in the same order as the widely used models based on the fragmental method, ClogP, and the atomic contribution method, AlogP, which are among the most used methods of predicting log P. PMID:22072945

  11. MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS

    SciTech Connect

    Leishear, R.

    2009-09-09

    Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels.

  12. Assessment of satellite derived diffuse attenuation coefficients and euphotic depths in south Florida coastal waters

    EPA Science Inventory

    Optical data collected in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010 were used to evaluate products derived with three bio-optical inversion algorithms applied to MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. Th...

  13. 40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...n-octanol/water), shake flask method. 799.6755 Section 799...of standardization. This method can be standardized. (d...distilling. More sophisticated methods will be required to separate...shaking at the temperature of the experiment. For doing this, it is...

  14. 40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...n-octanol/water), shake flask method. 799.6755 Section 799...of standardization. This method can be standardized. (d...distilling. More sophisticated methods will be required to separate...shaking at the temperature of the experiment. For doing this, it is...

  15. 40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...n-octanol/water), shake flask method. 799.6755 Section 799...of standardization. This method can be standardized. (d...distilling. More sophisticated methods will be required to separate...shaking at the temperature of the experiment. For doing this, it is...

  16. 40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...n-octanol/water), shake flask method. 799.6755 Section 799...of standardization. This method can be standardized. (d...distilling. More sophisticated methods will be required to separate...shaking at the temperature of the experiment. For doing this, it is...

  17. Use of NMR Imaging to Determine the Diffusion Coefficient of Water in Bio-based Hydrogels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The diffusion of liquid in a hydrogel material is a fundamental property which must be controlled in order to create effective delivery systems for the agricultural and pharmaceutical industries. NMR spectroscopy has been used to determine the diffusion of water and deuterium oxide in a bio-based h...

  18. Modeling of simultaneous heat and mass transfer processes in ammonia water absorption systems from general correlations

    NASA Astrophysics Data System (ADS)

    Sieres, Jaime; Fernández-Seara, José

    2007-11-01

    This paper presents a general differential mathematical model to analyze the simultaneous heat and mass transfer processes that occur in different components of an ammonia water absorption system: absorber, desorber, rectifier, distillation column, condenser and evaporator. Heat and mass transfer equations are considered, taking into account the heat and mass transfer resistances in the liquid and vapour phases. The model considers the different regions: vapour phase, liquid phase and an external heating or cooling medium. A finite difference numerical method has been considered to solve the resulting set of nonlinear differential equations and an iterative algorithm is proposed for its solution. A map of possible solutions of the mass transferred composition z is presented when varying the interface temperature, which enables to establish a robust implementation code. The analysis is focused on the processes presented in ammonia water absorption systems. The model is applied to analyze the ammonia purification process in an adiabatic packed rectification column and the numerical results show good agreement with experimental data.

  19. Water use, crop coefficients, and irrigation management criteria for camelina production in arid regions

    Microsoft Academic Search

    D. J. Hunsaker; A. N. French; T. R. Clarke; D. M. El-Shikha

    2011-01-01

    Camelina sativa (L.) Crantz is an oilseed crop touted as being suitable for production in the arid southwestern USA. However, because any\\u000a significant development of the crop has been limited to cooler, rain-fed climate-areas, information and guidance for managing\\u000a irrigated-camelina are lacking. This study measured the crop water use of a November-through-April camelina crop in Arizona\\u000a using frequent measurements of

  20. Global and local mass transfer coefficients in waste water treatment process by computational fluid dynamics

    Microsoft Academic Search

    A Cockx; Z Do-Quang; J. M Audic; A Liné; M Roustan

    2001-01-01

    Gas–liquid mass transfer is a currently used process in the waste water treatment industry. The objective today is to optimize the design and have a better control on the operation of these processes by using the CFD code ASTRID in two-phase flow reactors. A source term which represents interfacial mass transfer is introduced, accounting for two-phase flow hydrodynamics, it permits

  1. Water Absorption From Line-of-Sight Clouds Toward W49A

    E-print Network

    Rene Plume; Michael J. Kaufman; David A. Neufeld; Ronald L. Snell; David J. Hollenbach; Paul F. Goldsmith; John Howe; Edwin A. Bergin; Gary J. Melnick; Frank Bensch

    2004-01-22

    We have observed 6 clouds along the line-of-sight toward W49A using the Submillimeter Wave Astronomy Satellite (SWAS) and several ground-based observatories. The ortho-H2O 1-0 and OH (1665 and 1667 MHz) transitions are observed in absorption, whereas the low-J CO, 13CO, and C18O lines, as well as the [CI] 1-0 transition, are seen in emission. By using both the o-H218O and o-H2O absorption lines, we are able to constrain the column-averaged o-H_2O abundances in each line-of-sight cloud to within about an order of magnitude. Assuming the standard N(H2)/N(CO) ratio of 10^4, we find N(o-H2O)/N(H2) = 8.1 x 10^-8 - 4 x 10^-7 for three clouds with optically thin water lines. In three additional clouds, the H$_2$O lines are saturated so we have used observations of the H218O ground-state transition to find upper limits to the water abundance of 8.2x 10^-8 - 1.5x10^-6. We measure the OH abundance from the average of the 1665 and 1667 MHz observations and find N(OH)/N(H2) = 2.3x10^-7 - 1.1x10^-6. The o-H2O and OH abundances are similar to those determined for line-of-sight water absorption features towards W51 and Sgr B2 but are higher than those seen from water emission lines in molecular clouds. However, the clouds towards W49 have lower ratios of OH relative to H2O column densities than are predicted by simple models which assume that dissociative recombination is the primary formation pathway for OH and H2O. Building on the work of Neufeld et al. (2002), we present photo-chemistry models including additional chemical effects, which can also explain the observed OH and H2O column densities as well as the observed H2O/CO abundance ratios.

  2. Water Absorption from Line-of-Sight Clouds toward W49A

    NASA Astrophysics Data System (ADS)

    Plume, René; Kaufman, Michael J.; Neufeld, David A.; Snell, Ronald L.; Hollenbach, David J.; Goldsmith, Paul F.; Howe, John; Bergin, Edwin A.; Melnick, Gary J.; Bensch, Frank

    2004-04-01

    We have observed six clouds along the line of sight toward W49A using the Submillimeter Wave Astronomy Satellite and several ground-based observatories. The ortho-H2O 110-->101 and OH (1665 and 1667 MHz) transitions are observed in absorption, whereas the low-J CO, 13CO, and C18O lines, as well as the [C I] 3P1-3P0 transition, are seen in emission. The emission lines allow us to determine the gas density (n~1500-3000 cm-3) and CO column densities [N(CO)~7.9×1015-2.8×1017 cm-2] using a standard large velocity gradient analysis. By using both the o-H218O and o-H2O absorption lines, we are able to constrain the column-averaged o-H2O abundances in each line-of-sight cloud to within about an order of magnitude. Assuming the standard N(H2)/N(CO) ratio of 104, we find N(o-H2O)/N(H2)=8.1×10-8 to 4×10-7 for three clouds with optically thin water lines. In three additional clouds, the H2O lines are saturated, so we have used observations of the H218O ground-state transition to find upper limits to the water abundance of 8.2×10-8 to 1.5×10-6. We measure the OH abundance from the average of the 1665 and 1667 MHz observations and find N(OH)/N(H2)=2.3×10-7 to 1.1×10-6. The o-H2O and OH abundances are similar to those determined for line-of-sight water absorption features toward W51 and Sgr B2 but are higher than those seen from water emission lines in molecular clouds. However, the clouds toward W49 have lower ratios of OH relative to H2O column densities than are predicted by simple models, which assume that dissociative recombination is the primary formation pathway for OH and H2O. Building on the 2002 work of Neufeld and coworkers, we present photochemistry models including additional chemical effects, which can also explain the observed OH and H2O column densities, as well as the observed H2O/CO abundance ratios.

  3. Evaluating coal tar-water partitioning coefficient estimation methods and solute-solvent molecular interactions in tar phase.

    PubMed

    Endo, Satoshi; Xu, Wanjing; Goss, Kai-Uwe; Schmidt, Torsten C

    2008-09-01

    Equilibrium partitioning coefficients between an industrial coal tar sample and water (KCT/w) were determined for 41 polar and nonpolar solutes in batch systems. Together with literature values, 69 KCT/w data were analyzed using the following model approaches: Raoult's law, the single parameter linear free energy relationship (SPLFER) with octanol-water partitioning coefficients (Kow), the linear solvation energy relationships (LSERs), SPARC and COSMOtherm. Estimations by Raoult's law and the SPLFER agreed well with the experimental log KCT/w values for the investigated coal tar, with root mean square errors (RMSE) of 0.31 and 0.33, respectively. LSER resulted in as good estimations (RMSE=0.29) as the previous two. The LSER analysis revealed significant hydrogen (H)-bond acceptor properties of the studied coal tar phase. Using naphthalene as a surrogate solvent for the coal tar phase, SPARC and COSMOtherm provided fairly good predictions (RMSE of 0.63 and 0.65, respectively) of log KCT/w, without any additional empirical parameter. Further calculations using SPARC and COSMOtherm for partitioning between water and other tar-components (e.g., benzofuran, phenol and quinoline) suggested that minor components in coal tar do not significantly influence KCT/w of nonpolar solutes, and that Raoult's law and the SPLFER thus may be generally applied to these types of solutes, e.g., polycyclic aromatic hydrocarbons and alkylbenzenes, regardless of coal tar compositions. In contrast, partitioning of H-bonding solutes (e.g., phenols) can significantly vary depending on the amount of polar tar-components such as N-heterocyclic aromatic compounds. Therefore, the presented successful applications of Raoult's law and SPLFER to the studied coal tar could be a special case, and these simple approaches may not provide reasonable estimations for partitioning of H-bonding solutes from compositionally different coal tars. PMID:18649918

  4. K? absorption by locust gut and inhibition of ileal K? and water transport by FGLamide allatostatins.

    PubMed

    Robertson, Lisa; Donini, Andrew; Lange, Angela B

    2014-09-15

    The scanning ion-selective electrode technique (SIET) was utilized for the first time in Locusta migratoria to characterize K(+) transport along the digestive tract and to determine the effect of two locust FGLamide allatostatins (FGLa/ASTs) on K(+) transport: a previously sequenced FGLa/AST from Schistocerca gregaria (Scg-AST-6; ARPYSFGL-NH2) and a newly sequenced FGLa/AST from L. migratoria (Locmi-FGLa/AST-2; LPVYNFGL-NH2). Regional differences in K(+) fluxes along the gut were evident, where K(+) efflux in vitro (or absorption into the hemolymph in vivo) was greatest at the anterior ileum, and lowest at the colon. Ileal K(+) efflux was inhibited by both Scg-AST-6 and Locmi-FGLa/AST-2, with maximal inhibition at 10(-10) and 10(-11) mol l(-1), respectively. Both FGLa/ASTs also inhibited cAMP-stimulated K(+) efflux from the ileum. Locmi-FGLa/AST-2 also inhibited efflux of water across the ileum. Locusts are terrestrial insects living in dry climates, risking desiccation and making water conservation a necessity. The results suggest that FGLa/ASTs may be acting as diuretics by increasing K(+) excretion and therefore increasing water excretion. Thus it is likely that FGLa/ASTs are involved in the control of hemolymph water and ion levels during feeding and digestion, to help the locust deal with the excess K(+) load (and subsequently fluid) when the meal is processed. PMID:25013112

  5. Hemodialysis increases apparent diffusion coefficient of brain water in nephrectomized rats measured by isotropic diffusion-weighted magnetic resonance imaging.

    PubMed Central

    Galons, J P; Trouard, T; Gmitro, A F; Lien, Y H

    1996-01-01

    The nature of brain edema in dialysis disequilibrium syndrome (DDS) was investigated by diffusion-weighted magnetic resonance imaging (DWI). DWI was performed on normal or bilaterally nephrectomized rats before, and immediately after, hemodialysis. Hemodialysis was performed with a custom-made dialyzer (surface area 150 cm2) against a bicarbonate-buffered bath for 90 min with or without 70 mM urea. Hemodialysis with non-urea bath decreased plasma urea by 21 mM, and plasma osmolality by 22 mosmol/kg H2O, and increased brain water content by 8.0% (all < 0.05), while hemodialysis with urea bath did not affect plasma urea, osmolality, or brain water content. Three sets of axial DWI images of the brain were obtained at different gradient weighing factors with an in-plane resolution of 0.39 mm2. The apparent diffusion coefficient (Dapp) of the brain water was not affected by bilateral nephrectomy, or by hemodialysis in normal rats. In nephrectomized rats, brain Dapp was significantly increased after dialysis with non-urea bath (1.15 +/- 0.08 vs 0.89 +/- 0.07 x 10(-9)m2/sec, P < 0.01). No significant changes of brain water Dapp could be observed after dialysis with urea bath. The increased Dapp associated with DDS indicates that brain extracellular water increases and/or intracellular water decreases after hemodialysis. Our results strongly suggest that the brain edema induced by hemodialysis in uremic rats is due to interstitial edema rather than cytotoxic edema. Furthermore, our results support a primary role for the "reverse urea effect" in the pathogenesis of brain edema in DDS.DWI may be a useful diagnostic tool for DDS in patients with end-stage renal disease. PMID:8698867

  6. Prediction of urban water demand on the basis of Engel's coefficient and Hoffmann index: case studies in Beijing and Jinan, China.

    PubMed

    Zhi-Guo, Zhang; Yi-sheng, Shao; Zong-xue, Xu

    2010-01-01

    Domestic and industrial water uses are the most important segment of urban water consumption. Traditional urban water demand models are usually based on water consumption quotas or statistical relationships, which usually overestimate urban water demands. The efficiency of domestic and industrial water uses is associated with living standards and levels of industrialization. The correlation coefficient between per capita water consumption and Engel's Coefficient in Beijing and Jinan is 0.62 and 0.53, respectively. These values are much smaller than the correlation between added industrial value and the Hoffmann Index in Beijing (0.95) and Jinan (0.90). Demand models for urban water consumption, including a domestic water demand model based on Engel's Coefficient and an industrial water demand model based on the Hoffmann Index, were developed in this study to predict urban water demand in Beijing and Jinan for 2020. The results show that the models can effectively capture the trends of urban water demand. Urban water consumption in these two cities from 1995 to 2007 was used to calibrate the models. The coefficients of determination for residential and industrial water uses were 0.93 and 0.68 in Beijing, and 0.79 and 0.64 in Jinan. Social, economic and climate scenarios for Beijing and Jinan in 2020 were generated according to the Urban Master Plans for these two cities, and they formed the basis for predictions of water consumption in 2020. The results show that total water consumption will increase by 67.6% in Jinan and 33.0% in Beijing when compared with consumption from 2007. PMID:20651447

  7. Characterization of the aramid\\/epoxy interfacial properties by means of pull-out test and influence of water absorption

    Microsoft Academic Search

    Kazuto Tanaka; Kohji Minoshima; Witold Grela; Kenjiro Komai

    2002-01-01

    Single fiber pull-out tests were carried out to investigate the influence of water absorption on the interfacial properties of aramid\\/epoxy composite. The fiber\\/matrix interfacial strength was severely decreased between 4 and 7 week immersion time in deionized water at 80 °C, and thereafter showed a plateau. This change with immersion time did not correspond with that of the water gain of

  8. Absorption of insulin using water-in-oil-in-water emulsion from an enteral loop in rats.

    PubMed

    Matsuzawa, A; Morishita, M; Takayama, K; Nagai, T

    1995-12-01

    The present work was undertaken to prepare water-in-oil-in-water (W/O/W) emulsions as a carrier for insulin via the enteral route. The emulsions were prepared by a two-step procedure using a homogenizer. To avoid insulin escape from the inner aqueous phase, 3, 5, or 10% gelatin was added in the inner phase. The oily phase was composed of 5% lecithin, 20% Span 80 and 75% soybean oil. The purified water containing 3% Tween 80 was used for the outer aqueous phase. In addition, these emulsions were filtered with a membrane filter (0.45 micron) to obtain smaller emulsion particles. The stability of the emulsions was evaluated by a turbidity measurement method and photomicrographic observation. By the addition of gelatin to the inner aqueous phase and storage at 4 degrees C, the stability of the emulsions could be improved. The hypoglycemic effects of insulin after administration of emulsion to the stomach, the duodenum, the jejunum, the ileum and the colon were examined using an in situ loop method in rats. A significant hypoglycemic effect was observed at the ileum and colon loops after administration of the filtered emulsions containing 5% gelatin in the inner phase. These findings suggest that the W/O/W multiple emulsions stabilized by gelatin can improve ileal and colonic absorption of insulin. PMID:8787795

  9. Effect of liposomes on the absorption of water-soluble active pharmaceutical ingredients via oral administration.

    PubMed

    Yang, Zhijun; Lu, Aiping; Wong, Blenda Chi Kwan; Chen, Xiaoyu; Bian, Zhaoxiang; Zhao, Zhongzhen; Huang, Wenhua; Zhang, Ge; Chen, Hubiao; Xu, Min

    2013-01-01

    The objective of this study was to investigate the effect of liposomes on the absorption of water-soluble active pharmaceutical ingredients. Salbutamol sulfate (SBS) has been widely used for treatment of bronchospasm in conditions such as asthma. Using SBS as the model drug in this study, we developed SBS-loaded liposomes for oral administration and explored the relationship between their bioavailability and anti-asthmatic efficacy. SBS was entrapped in liposomes with encapsulation efficiency as high as 70%. The in vitro transport profile of SBS across a dialysis membrane for liposome suspension was compared with that for free SBS solution. Oral administration of liposomes labeled with the fluorescent dye 1,1'-dioctadecyltetramethyl indotricarbocyanine iodide (DiR) in a mouse model was assessed by a small animal imaging system. Pharmacokinetic and pharmacodynamic studies on SBS liposome suspension and free SBS solution were performed using animal models via oral administration. The results showed that liposomes could sustain the release of SBS in vitro and decrease the transport rate of SBS across the dialysis membrane. In vivo fluorescence imaging analysis demonstrated DiR liposome distribution in mouse stomach for at least 24 hr. The mean residence time of SBS from liposomes was found to be longer than that of free SBS, suggesting that the relative bioavailability of SBS was higher when liposome delivery was used. The pharmacokinetic data also showed that the drug absorption rate was relatively slower for treatment with liposomal SBS when compared to free SBS. Moreover, SBS liposome suspension was shown to give a prolonged anti-asthmatic effect after oral administration when compared to free SBS solution. Overall, this study demonstrated that use of liposomes as delivery vehicles for sustained drug release and controlled absorption could be a promising approach for improving the therapeutic potency of active pharmaceutical ingredients. PMID:23621538

  10. Laboratory Measurements of the 940, 1130, and 1370 nm Water Vapor Absorption Band Profiles

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Gore, Warren J.; Pilewskie, P.; Freedman, R. S.; Chackerian, C., Jr.; Varanasi, P.

    2001-01-01

    We have used the solar spectral flux radiometer (SSFR) flight instrument with the Ames 25 meter base-path White cell to obtain about 20 moderate resolution (8 nm) pure water vapor spectra from 650 to 1650 nm, with absorbing paths from 806 to 1506 meters and pressures up to 14 torr. We also obtained a set at 806 meters with several different air-broadening pressures. Model simulations were made for the 940, 1130, and 1370 nm absorption bands for some of these laboratory conditions using the Rothman, et al HITRAN-2000 linelist. This new compilation of HITRAN includes new intensity measurements for the 940 nm region. We compared simulations for our spectra of this band using HITRAN-2000 with simulations using the prior HITRAN-1996. The simulations of the 1130 nm band show about 10% less absorption than we measured. There is some evidence that the total intensity of this band is about 38% stronger than the sum of the HITRAN line intensities in this region. In our laboratory conditions the absorption depends approximately on the square root of the intensity. Thus, our measurements agree that the band is stronger than tabulated in HITRAN, but by about 20%, substantially less than the published value. Significant differences have been shown between Doppler-limited resolution spectra of the 1370 nm band obtained at the Pacific Northwest National Laboratory and HITRAN simulations. Additional new intensity measurements in this region are continuing to be made. We expect the simulations of our SSFR lab data of this band will show the relative importance of improving the HITRAN line intensities of this band for atmospheric measurements.

  11. Effect of aminoalkyl methacrylate copolymer E/HCl on in vivo absorption of poorly water-soluble drug.

    PubMed

    Yoshida, Takatsune; Kurimoto, Ippei; Yoshihara, Keiichi; Umejima, Hiroyuki; Ito, Naoki; Watanabe, Shunsuke; Sako, Kazuhiro; Kikuchi, Akihiko

    2013-11-01

    This study aimed to investigate in vivo absorption of tacrolimus formulated as a solid dispersion using Eudragit E®/HCl (E-SD). E-SD is an aminoalkyl methacrylate copolymer that can be dissolved under neutral pH conditions. E-SD was used alone as a solid dispersion carrier and/or was mixed with tacrolimus primarily dispersed with hydroxypropylmethylcellulose (HPMC). Tacrolimus was formulated with E-SD at several different ratios. Formulations with tacrolimus/E-SD ratio of 1/3 showed higher in vivo absorption, compared to tacrolimus dispersed in the excipients (primarily HPMC) found in commercially available tacrolimus capsules, using a rat in situ closed loop method. Good correlation was observed between in vitro drug solubility and in vivo drug absorption. In vitro solubility tests and rat oral absorption studies of tacrolimus/HPMC solid dispersion formulations were also conducted after mixing the HPMC dispersion with several ratios of E-SD. E-SD/tacrolimus/HPMC formulations yielded high in vitro drug solubility but comparatively low in vivo absorption. Dog oral absorption studies were conducted using capsules containing a formulation of tacrolimus/E-SD at a ratio of 1/5. The E-SD formulation-containing capsule showed higher in vivo drug absorption than tacrolimus dispersed in the standard HPMC capsule. These studies report enhancement of the in vivo absorption of a poorly water-soluble drug following dispersion with E-SD when compared to formulation in HPMC. PMID:23062024

  12. Comparison of x-ray absorption spectra between water and ice: new ice data with low pre-edge absorption cross-section.

    PubMed

    Sellberg, Jonas A; Kaya, Sarp; Segtnan, Vegard H; Chen, Chen; Tyliszczak, Tolek; Ogasawara, Hirohito; Nordlund, Dennis; Pettersson, Lars G M; Nilsson, Anders

    2014-07-21

    The effect of crystal growth conditions on the O K-edge x-ray absorption spectra of ice is investigated through detailed analysis of the spectral features. The amount of ice defects is found to be minimized on hydrophobic surfaces, such as BaF2(111), with low concentration of nucleation centers. This is manifested through a reduction of the absorption cross-section at 535 eV, which is associated with distorted hydrogen bonds. Furthermore, a connection is made between the observed increase in spectral intensity between 544 and 548 eV and high-symmetry points in the electronic band structure, suggesting a more extended hydrogen-bond network as compared to ices prepared differently. The spectral differences for various ice preparations are compared to the temperature dependence of spectra of liquid water upon supercooling. A double-peak feature in the absorption cross-section between 540 and 543 eV is identified as a characteristic of the crystalline phase. The connection to the interpretation of the liquid phase O K-edge x-ray absorption spectrum is extensively discussed. PMID:25053326

  13. Development of a UAV-based differential absorption lidar for measuring atmospheric water vapor

    NASA Astrophysics Data System (ADS)

    Thomas, Brian William

    Differential Absorption Lidar (DIAL) is a remote sensing technique useful for making range resolved measurements of chemical species. A water vapor DIAL system was developed for use on a high altitude unmanned air vehicle (UAV), in order to study water vapor distribution in hurricanes. The system uses a diode-pumped Cr:LiSAF laser to probe water vapor absorption lines at or near 815 nm. The receiver is comprised of two detectors, an analog mode avalanche photodiode (APD), and a photon counting APD, which gives the receiver a dynamic range of 5 orders of magnitude. Data acquisition is done with a 12-bit digitizer and a separate digital counter for the photon counting APD. The data is stored locally for retrieval at the end of the mission. The system was designed for fully autonomous operation. The DIAL system was tested on the ground in a zenith looking configuration. The system demonstrated measurements of water vapor to a range of 1800 m, with a difference from local balloon sonde data of no more than 30--50% over that range. Tests showed that the system measurement uncertainty was dominated by limitations of the digitizer, which will not be a factor during airborne operation. Estimates of airborne performance suggest that, flying at an altitude of 20 km, the system is currently capable of measuring water vapor between 2 and 7.5 km with an uncertainty of <50%. This can be reduced to <10% uncertainty with a factor of 3 increase in return signal. Refinement of the system is therefore recommended with an emphasis on increasing laser pulse energy. This dissertation describes the development of the DIAL system including motivation for the research, computer modeling of the return signal, selection of system components, and the testing process at the component and system levels. The system design requirements and goals are presented and used as a basis for component selection. The test results are used to extrapolate an estimate of the airborne performance of the system, and recommendations for future development of the system are made based on these estimates.

  14. Intrinsic UV absorption spectrometry observed with a liquid core waveguide as a sensor technique for monitoring ozone in water.

    PubMed

    Le, Trang; Tao, Shiquan

    2011-08-21

    The industrial use of ozone as a sanitizing agent in water treatment and food processing in recent years calls for sensor technologies for monitoring ozone in water for process control. Ozone molecules absorb UV light with a peak absorption wavelength at 254 nm. This property has been used in this work to develop a simple sensor technology for online, real-time continuous monitoring of trace ozone in water. A Teflon AF2400 tube filled with pure water forms a liquid core waveguide (LCW), which is used as a long-path-length optical absorption cell. This pure water filled tube was deployed into a water sample. Ozone molecules dissolved in the water sample permeate through the Teflon AF2400 tube wall and dissolve in water filled in the tube. This prevents interference species from entering the LCW, and eliminates interferences. The optical absorption signal of the long-path-length cell at 254 nm measured by guiding light through the LCW is used as a sensing signal. This simple structured sensor does not involve any chemical reagent, is reversible, and has a response time <4.5 minutes. It can be used to detect ozone in water samples down to 3.6 × 10(-9) mol L(-1). PMID:21743914

  15. Variability of Water and Oxygen Absorption Bands in the Disk-Integrated Spectra of the Earth

    E-print Network

    Fujii, Yuka; Suto, Yasushi

    2013-01-01

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of the Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of the Earth provided by the EPOXI mission, and find 5-20% fractional variation of the absorption depths of H2O and O2 bands, two molecules that have major signatures in the observed range. From a correlation analysis with the cloud map data from the Earth Observing Satellite (EOS), we find that their variation pattern is primarily due to the uneven cloud cover distribution. In order to account for the observed variation quantitatively, we consider a simple opaque cloud model, which assumes that the clouds totally block the spectral influence of the atmosphere below the cloud layer, equivalent to assuming that the incident light is completely scattered at the cloud top level. The model is reasonably successful, and reproduces the EPOXI data from the pixel-level EOS cloud/water vapor ...

  16. Aqueous solubilities, vapor pressures, and 1-octanol-water partition coefficients for C9-C14 linear alkylbenzenes

    USGS Publications Warehouse

    Sherblom, P.M.; Gschwend, P.M.; Eganhouse, R.P.

    1992-01-01

    Measurements and estimates of aqueous solubilities, 1-octanol-water partition coefficients (Kow), and vapor pressures were made for 29 linear alkylbenzenes having alkyl chain lengths of 9-14 carbons. The ranges of values observed were vapor pressures from 0.002 to 0.418 Pa, log Kow, from 6.83 to 9.95, and aqueous solubilities from 4 to 38 nmol??L-1. Measured values exhibited a relationship to both the alkyl chain length and the position of phenyl substitution on the alkyl chain. Measurement of the aqueous concentrations resulting from equilibration of a mixture of alkylbenzenes yielded higher than expected values, indicating cosolute or other interactive effects caused enhanced aqueous concentrations of these compounds. ?? 1992 American Chemical Society.

  17. Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.

    1994-01-01

    Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

  18. Evaluation of tropospheric water vapor profiling using eye-safe, infrared differential absorption lidar

    SciTech Connect

    Rye, B.J. [Colorado Univ., Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences]|[National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.; Machol, J.L.; Grund, C.J.; Hardesty, R.M. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.

    1996-05-14

    Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution are fundamental to the success of the ARM CART program. In addition, these should be acquired over long periods at low operational and maintenance cost. The development and verification of realistic climate model parameterizations for clouds and net radiation balance, and the correction of other CART site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. To date, application of profiles have been limited by vertical resolution and uniqueness and high operating cost, or diminished daytime performance, lack of eye-safety, and high maintenance cost. Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the studies reported here, we develop DIAL system performance models and examine the potential of solving some of the shortcomings of previous methods using parameters representative of current technologies. These simulations are also applied to determine the strengths and weaknesses unique to the DIAL method for this application.

  19. Starch-based hydrogel loading with carbendazim for controlled-release and water absorption.

    PubMed

    Bai, Chan; Zhang, Sufen; Huang, Lei; Wang, Haiyan; Wang, Wei; Ye, Qingfu

    2015-07-10

    Starch, with properties of eco-friendliness and abundance, is one of the most important natural polymers. Starch-based hydrogels were investigated as carriers of carbendazim to combine controlled-release and water absorption (WA). Three carbendazim-loaded hydrogels (CLHs) with different WA capacities were prepared by solution polymerization. The CLHs were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and liquid-chromatography mass-spectrometry (LC-MS/MS). Release kinetics of CLHs was investigated using (14)C-labeling method. The diffusion parameters of CLHs were 0.47, 0.57 and 0.81 in deionized H2O (ddH2O). WA affected release profile significantly, the release longevity reaching 240h when WA was 800g/g in ddH2O. Solution pH influenced release profiles and the lowest release rate occurred in the lowest pH. Addition of CLH (1.3g/kg soil) markedly increased water-holding capacity (WHC) of soil by 8.2%. The study indicated that starch-based CLH was a good controlled-release agent for carbendazim and water absorbent for soil. PMID:25857995

  20. A Water Vapor Differential Absorption LIDAR Design for Unpiloted Aerial Vehicles

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell J.; Mead, Patricia F.

    2004-01-01

    This system study proposes the deployment of a water vapor Differential Absorption LIDAR (DIAL) system on an Altair unmanned aerial vehicle (UAV) platform. The Altair offers improved payload weight and volume performance, and longer total flight time as compared to other commercial UAV's. This study has generated a preliminary design for an Altair based water vapor DIAL system. The design includes a proposed DIAL schematic, a review of mechanical challenges such as temperature and humidity stresses on UAV deployed DIAL systems, an assessment of the available capacity for additional instrumentation (based on the proposed design), and an overview of possible weight and volume improvements associated with the use of customized electronic and computer hardware, and through the integration of advanced fiber-optic and laser products. The results of the study show that less than 17% of the available weight, less than 19% of the volume capacity, and approximately 11% of the electrical capacity is utilized by the proposed water vapor DIAL system on the Altair UAV.