Sample records for water absorption coefficient

  1. Absorption coefficient instrument for turbid natural waters.

    PubMed

    Friedman, E; Poole, L; Cherdak, A; Houghton, W

    1980-05-15

    An instrument has been developed that directly measures the multispectral absorption coefficient of turbid natural water. The design incorporates methods for compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in background light level. When used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques. PMID:20221099

  2. Absorption coefficient instrument for turbid natural waters

    NASA Astrophysics Data System (ADS)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-05-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  3. Absorption coefficient instrument for turbid natural waters

    NASA Technical Reports Server (NTRS)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-01-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  4. Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter

    Microsoft Academic Search

    Ling Wang

    2008-01-01

    The integrating cavity absorption meter (ICAM) has been used successfully to measure the low absorption coefficient of pure water. The ICAM produces an effective total path length of several meters or even longer, although the physical size of the instrument is only several centimeters. The long effective total path length ensures a high sensitivity that enables the ICAM to measure

  5. 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

  6. Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter

    NASA Astrophysics Data System (ADS)

    Wang, Ling

    2008-10-01

    The integrating cavity absorption meter (ICAM) has been used successfully to measure the low absorption coefficient of pure water. The ICAM produces an effective total path length of several meters or even longer, although the physical size of the instrument is only several centimeters. The long effective total path length ensures a high sensitivity that enables the ICAM to measure liquid mediums with low absorption. Compared to the conventional transmission type of instruments that were used to measure the same medium with the same path length, the ICAM eliminates the effect of scattering by introducing isotropic illumination in the medium, and consequently measures the true absorption coefficient of the medium in stead of the attenuation coefficient. The original ICAM was constructed with Spectralon and used in the wavelength range from 380 nm to 700 nm. Later studies showed that Spectralon is not suitable for measurements in the UV region because of its relatively lower reflectivity in this region and, even worse, the continuously decaying reflectivity under the exposure to UV radiation. Thus, we have developed a new way to construct the ICAM utilizing the material fumed silica. The resulting ICAM has a high sensitivity even in the UV region and doesn't have the deterioration problem. The measurement results from the new ICAM are in good agreement with the existing results. The absorption coefficients of pure water at wavelengths between 250 nm and 400 nm are presented here.

  7. Absorption coefficients for water vapor at 193 nm from 300 to 1073 K

    NASA Technical Reports Server (NTRS)

    Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.

    1993-01-01

    Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.

  8. IR Absorption Coefficients for the Quantification of Water in Hydrous Ringwoodite

    Microsoft Academic Search

    S. Thomas; S. D. Jacobsen; C. R. Bina; J. R. Smyth; D. J. Frost

    2009-01-01

    Raman spectroscopy, combined with the `Comparator technique' has been developed to determine water contents ranging from a few wt ppm to wt% in glasses and nominally anhydrous minerals including garnets, olivine, and SiO2 polymorphs (Thomas et al. 2009). The routine is one promising example of quantification tools to determine mineral specific molar absorption coefficients (?) for IR spectroscopy. Mineral specific

  9. IR Absorption Coefficients for the Quantification of Water in Hydrous Ringwoodite

    Microsoft Academic Search

    Sylvia-Monique Thomas; Steven D. Jacobsen; Craig R. Bina; Joseph R. Smyth; Daniel J. Frost

    2010-01-01

    Raman spectroscopy, combined with the 'Comparator technique' has been developed to determine water contents ranging from a few wt ppm to wt% in glasses and nominally anhydrous minerals including garnets, olivine, and SiO2 polymorphs (Thomas et al. 2009). The routine is one promising example of quantification tools to determine mineral specific molar absorption coefficients (?) for IR spectroscopy. Mineral specific

  10. 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

  11. Water vapor absorption coefficients in the 8-13-micron spectral region - A critical review

    NASA Technical Reports Server (NTRS)

    Grant, William B.

    1990-01-01

    Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source and filters, a White cell and a CO2 laser or a broadband source and a spectrometer, and a spectrophone with a CO2 laser. Advantages and disadvantages of each measurement approach are given as a guide to further research. Continuum absorption has apparently been measured accurately to about the 5-10 percent level in five of the measurements reported.

  12. Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter. 

    E-print Network

    Wang, Ling

    2008-10-10

    coefficient. The original ICAM was constructed with Spectralon and used in the wavelength range from 380 nm to 700 nm. Later studies showed that Spectralon is not suitable for measurements in the UV region because of its relatively lower reflectivity...

  13. A comparison of methods for the measurement of the absorption coefficient in natural waters

    NASA Technical Reports Server (NTRS)

    Pegau, W. Scott; Cleveland, Joan S.; Doss, W.; Kennedy, C. Dan; Maffione, Robert A.; Mueller, James L.; Stone, R.; Trees, Charles C.; Weidemann, Alan D.; Wells, Willard H.

    1995-01-01

    In the spring of 1992 an optical closure experiment was conducted at Lake Pend Orielle, Idaho. A primary objective of the experiment was to compare techniques for the measurement of the spectral absorption coefficent and other inherent optical properties of natural waters. Daily averages of absorption coefficents measured using six methods are compared at wavelengths of 456, 488, and 532 nm. Overall agreement was within 40% at 456 nm and improved with increasing wavelength to 25% at 532 nm. These absorption measurements were distributed over the final 9 days of the experiement, when bio-optical conditions in Lake Pend Oreille (as indexed by the beam attenuation coefficent c(sub p)(660) and chlorophyll a fluorescence profiles) were representative of those observed throughout the experiment. However, profiles of stimulated chlorophyll a fluorescence and beam transmission showed that bio-optical properties in the lake varied strongly on all time and space scales. Therefore environmental variabilty contributed significantly to deviations between daily mean absorption coefficients measured using the different techniques.

  14. Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region.

    PubMed

    Röttgers, Rüdiger; McKee, David; Utschig, Christian

    2014-10-20

    The light absorption coefficient of water is dependent on temperature and concentration of ions, i.e. the salinity in seawater. Accurate knowledge of the water absorption coefficient, a, and/or its temperature and salinity correction coefficients, ?(T) and ?(S), respectively, is essential for a wide range of optical applications. Values are available from published data only at specific narrow wavelength ranges or at single wavelengths in the visible and infrared regions. ?(T) and ?(S) were therefore spectrophotometrically measured throughout the visible, near, and short wavelength infrared spectral region (400 to ~2700 nm). Additionally, they were derived from more precise measurements with a point-source integrating-cavity absorption meter (PSICAM) for 400 to 700 nm. When combined with earlier measurements from the literature in the range of 2600 - 14000 nm (wavenumber: 3800 - 700 cm(-1)), the coefficients are provided for 400 to 14000 nm (wavenumber: 25000 to 700 cm(-1)). PMID:25401542

  15. Parameterization of the chlorophyll a -specific in vivo light absorption coefficient covering estuarine, coastal and oceanic waters

    Microsoft Academic Search

    P. A. Stæhr; S. Markager

    2004-01-01

    We evaluated models predicting the spectral chlorophyll-a (Chl a)-specific absorption coefficient (a*ph (?)) from Chl a concentration [Chl a] on the basis of 465 phytoplankton absorption spectra collected in estuarine, coastal and oceanic waters. A power model on ln-transformed data provided the best model fit compared to a power model on non-transformed data previously applied to parameterize the relationship between

  16. Measurement of the continuum absorption coefficient of water vapor near 14400 cm-1 (0.694 ?m)

    NASA Astrophysics Data System (ADS)

    Tikhomirov, A. B.; Ptashnik, I. V.; Tikhomirov, B. A.

    2006-07-01

    The continuum absorption coefficient (CAC) of water vapor ( k cont) in the visible region is determined for the first time from the data of laboratory measurements. For this purpose, the absorption spectra of water vapor in the region 14395-14402 cm-1 are recorded with the aid of a high-sensitivity photoacoustic spectrometer with a frequency-tunable single-pulse ruby laser, and the absorption measured in this transparency microwindow is compared with that calculated based on the HITRAN 2004 data bank. In the spectral region under study, k cont = (0.53 ± 0.18) × 10-9 cm-1 mbar-1 at a total pressure of a water vapor-nitrogen mixture of 1000 mbar and a temperature of 295 K. This value of the CAC is roughly 23% higher than the CAC value in the IO-CKD model of the continuum.

  17. A model for partitioning the light absorption coefficient of natural waters into phytoplankton, nonalgal particulate, and colored dissolved organic components: A case study for the Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Zheng, Guangming; Stramski, Dariusz; DiGiacomo, Paul M.

    2015-04-01

    We present a model, referred to as Generalized Stacked-Constraints Model (GSCM), for partitioning the total light absorption coefficient of natural water (with pure-water contribution subtracted), anw(?), into phytoplankton, aph(?), nonalgal particulate, ad(?), and CDOM, ag(?), components. The formulation of the model is based on the so-called stacked-constraints approach, which utilizes a number of inequality constraints that must be satisfied simultaneously by the model outputs of component absorption coefficients. A major advancement is that GSCM provides a capability to separate the ad(?) and ag(?) coefficients from each other using only weakly restrictive assumptions about the component absorption coefficients. In contrast to the common assumption of exponential spectral shape of ad(?) and ag(?) in previous models, in our model these two coefficients are parameterized in terms of several distinct spectral shapes. These shapes are determined from field data collected in the Chesapeake Bay with an ultimate goal to adequately account for the actual variability in spectral shapes of ad(?) and ag(?) in the study area. Another advancement of this model lies in its capability to account for potentially nonnegligible magnitude of ad(?) in the near-infrared spectral region. Evaluation of model performance demonstrates good agreement with measurements in the Chesapeake Bay. For example, the median ratio of the model-derived to measured ad(?), ag(?), and aph(?) at 443 nm is 0.913, 1.064, and 1.056, respectively. Whereas our model in its present form can be a powerful tool for regional studies in the Chesapeake Bay, the overall approach is readily adaptable to other regions or bio-optical water types.

  18. Water absorption lines, 931-961 nm - Selected intensities, N2-collision-broadening coefficients, self-broadening coefficients, and pressure shifts in air

    NASA Technical Reports Server (NTRS)

    Giver, L. P.; Gentry, B.; Schwemmer, G.; Wilkerson, T. D.

    1982-01-01

    Intensities were measured for 97 lines of H2O vapor between 932 and 961 nm. The lines were selected for their potential usefulness for remote laser measurements of H2O vapor in the earth's atmosphere. The spectra were obtained with several different H2O vapor abundances and N2 broadening gas pressures; the spectral resolution was 0.046/cm FWHM. Measured H2O line intensities range from 7 x 10 to the -25th to 7 x 10 to the -22nd/cm per (molecules/sq cm). H2O self-broadening coefficients were measured for 13 of these strongest lines; the mean value was 0.5/cm per atm. N2-collision-broadening coefficients were measured for 73 lines, and the average was 0.11 cm per atm HWHM. Pressure shifts in air were determined for a sample of six lines between 948 and 950 nm; these lines shift to lower frequency by an amount comparable to 0.1 of the collision-broadened widths measured in air or N2. The measured intensities of many lines of 300-000 band are much larger than expected from prior computations, in some cases by over an order of magnitude. Coriolis interactions with the stronger 201-000 band appear to be the primary cause of the enhancement of these line intensities.

  19. 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 ...

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

    PubMed Central

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

    2011-01-01

    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 254nm (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 (Stadler et al., Wat. Sci. Technol. 58(4): 899-909, 2008). 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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. Specific absorption coefficient and the phytoplankton package effect in Lake Taihu, China

    Microsoft Academic Search

    Chengfeng Le; Yunmei Li; Yong Zha; Deyong Sun

    2009-01-01

    In order to investigate variations of absorption and total chlorophyll-a (TChl-a)-specific absorption coefficient of phytoplankton in Lake Taihu, 57 water samples obtained from Lake Taihu during November\\u000a 8–22, 2007 were used in this study. Package effect and accessory pigments’ influences on the absorption spectra were also\\u000a examined. Phytoplankton absorption was measured by quality filter technical, and TChl-a concentration was measured

  6. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO

    Microsoft Academic Search

    N. A. Marley; A. Marchany-Rivera; K. L. Kelley; A. Mangu; J. S. Gaffney

    2007-01-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to

  7. 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.

  8. Equivalent absorption coefficients generated from frequency probability distributions

    NASA Technical Reports Server (NTRS)

    Ackerman, T. P.

    1983-01-01

    A flexible and computationally accurate method of treating aerosol scattering in spectral regions in which gaseous absorption is important is described. In the method, line-by-line absorption coefficients are computed as a function of pressure, temperature, and absorber gas for the spectral region of interest. The coefficients are sorted into a probability distribution which is converted into a cumulative probability distribution, which in turn can be inverted due to its monotonic nature. The inverted distribution is a smooth curve giving the absorption coefficient as a function of an independent variable on the domain. The frequency integration of the radiative transfer equation can then be performed by a quadrature technique with values of the absorption coefficient determined from the inverted distribution curve. The method is illustrated by applying it to the 9.6 micron band of ozone.

  9. Determination of absorption coefficient of skin melanin in visible and NIR spectral region

    Microsoft Academic Search

    Igor V. Meglinsky; Stephen J. Matcher

    2000-01-01

    By assuming a wavelength independent scattering coefficients for different skin layers and using the known wavelength dependence of the absorption coefficient of oxy- and deoxy- hemoglobin and water, we have simulated the reflection spectra from skin with various level of blood oxygen saturation. Comparison of the simulation results with experimental measurements made in vivo make it possible to estimate the

  10. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  11. Sublimation Coefficient of Water Ice

    NASA Astrophysics Data System (ADS)

    Kossacki, K. J.; Markiewicz, W. J.; Skorov, Y.; Koemle, N. I.

    1999-09-01

    In simulations of evolution of cometary nuclei it is commonly assumed that the coefficients of sublimation and condensation of the volatiles are both equal to one. However, the laboratory investigation of water ice samples under cometary-like conditions (Kossacki et al., 1997) suggests, that the sublimation flux calculated with the Hertz-Knudsen formula and the above assumption is nearly an order of magnitude too high. A similar conclusion can be drawn from the results of various experiments on growth from vapour phase and sublimation of ice crystals (Lamb and Scott, 1972; Beckmann and Lacmann, 1982; Sei and Gonda, 1989). These results imply that the sublimation coefficient can be as low as 0.1. The above coefficients depend on various parameters such as temperature, concentration of surface impurities as well as deviation of the vapour pressure from that of the phase equilibrium. In this work we discuss the temperature dependence of both of these coefficients. We also propose an empirical formula to fit the temperature dependence. This new formulation is also used to analyse the implications for the thermal conductivity of a porous cometary-like ice.

  12. Impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data

    NASA Astrophysics Data System (ADS)

    Li, Xiaoqi; Jiang, Huabei

    2013-02-01

    We present a study through extensive simulation that considers the impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data collected from media mimicking breast tissue. We found that while the impact of scattering heterogeneities/targets is modest on photoacoustic recovery of optical absorption coefficients, the impact of scattering contrast caused by adipose tissue, a layer of normal tissue along the boundary of the breast, is dramatic on reconstruction of optical absorption coefficients using photoacoustic data—up to 25.8% relative error in recovering the absorption coefficient is estimated in such cases. To overcome this problem, we propose a new method to enhance photoacoustic recovery of the optical absorption coefficient in heterogeneous media by considering inhomogeneous scattering coefficient distribution provided by diffuse optical tomography (DOT). Results from extensive simulations show that photoacoustic recovery of absorption coefficient maps can be improved considerably with a priori scattering information from DOT.

  13. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  14. 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.

  15. A method for monitoring nuclear absorption coefficients of aviation fuels

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Shen, Chih-Ping

    1989-01-01

    A technique for monitoring variability in the nuclear absorption characteristics of aviation fuels has been developed. It is based on a highly collimated low energy gamma radiation source and a sodium iodide counter. The source and the counter assembly are separated by a geometrically well-defined test fuel cell. A computer program for determining the mass attenuation coefficient of the test fuel sample, based on the data acquired for a preset counting period, has been developed and tested on several types of aviation fuel.

  16. Analysis of the evaporation coefficient and the condensation coefficient of water

    Microsoft Academic Search

    R. Marek; J. Straub

    2001-01-01

    The evaporation and condensation coefficients of water are extensively analyzed considering also data hitherto not taken into account. From the performed evaluation, a decline of both coefficients with increasing temperature and pressure is derived. For water, the condensation coefficients is generally higher than the evaporation coefficient. Evaporation and condensation coefficients exceed 0.1 for dynamically renewing water surfaces, while the analysis

  17. Spatial variability of phytoplankton absorption coefficients and pigments off Baja California during November 2002

    Microsoft Academic Search

    Óscar A. Barocio-León; Roberto Millán-Núñez; Eduardo Santamaría-del-Ángel; Adriana González-Silvera; Charles C. Trees

    2006-01-01

    We have estimated the spatial variability of phytoplankton specific absorption coefficients (a*\\u000a ph\\u000a ) in the water column of the California Current System during November 2002, taking into account the variability in pigment\\u000a composition and phytoplankton community structure and size. Oligotrophic conditions (surface Chl ?3) dominated offshore, while mesotrophic conditions (surface Chl 0.2 to 2.0 mg m?3) where found inshore.

  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. Large nonlinear absorption and refraction coefficients of carbon nanotubes estimated from femtosecond z-scan measurements

    NASA Astrophysics Data System (ADS)

    Kamaraju, N.; Kumar, Sunil; Sood, A. K.; Guha, Shekhar; Krishnamurthy, Srinivasan; Rao, C. N. R.

    2007-12-01

    Nonlinear transmission of 80 and 140fs pulsed light with 0.79?m wavelength through single walled carbon nanotubes suspended in water containing sodium dodecyl sulfate is studied. Pulse-width independent saturation absorption and negative cubic nonlinearity are observed, respectively, in open and closed aperture z-scan experiments. The theoretical expressions derived to analyze the z-dependent transmission in the saturable limit require two photon absorption coefficient ?0˜1.4cm/MW and a nonlinear index ? ˜-5.5×10-11cm2/W to fit the data.

  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. Measurement of the absorption coefficient of a glucose solution through transmission of light and polarymetry techniques

    NASA Astrophysics Data System (ADS)

    Yáñez M., J.

    2011-10-01

    Diabetes is a disease with no cure, but can be controlled to improve the quality of life of sufferers. Currently there are means to control, but this means they have the disadvantage that in order to measure the amount of glucose is necessary to take blood samples that are painful. This paper presents a system for measuring glucose using non-invasive optical techniques: using absorption spectroscopy and polarimetry technique. It shows the results obtained from experiments done on samples containing distilled water and different amounts of glucose to study the absorption coefficient of glucose with both techniques. Water is used because it is one of the main elements in the blood and interferes with glucose measurement. This experiment will develop a prototype to measure glucose through a non-invasive technique.

  2. Ultra-violet Absorption of Sea Water

    Microsoft Academic Search

    F. A. J. ARMSTRONG; G. T. BOALCH

    1961-01-01

    The intensity of submarine daylight is of such importance to the growth of marine plants that much attention has been given to measurements of the absorption of solar radiation by sea water. It has long been known that absorption is least in the blue green in the visible spectrum, and Tsukamoto (1927) showed that the absorption of ultra-violet radiation increased

  3. Diurnal Variations in the Specific Absorption Coefficient: Recent Results from Mexico City

    Microsoft Academic Search

    D. Baumgardner; G. Kok; G. B. Raga

    2005-01-01

    The specific absorption coefficient, sigmaa, defined as the absorbance of light per unit path length and per unit of mass concentration, is an important, radiative property of the atmosphere and is also used as a conversion factor when estimating the mass of light absorbing material, usually black carbon, from measurements of the absorption coefficient. The magnitude of sigmaa varies over

  4. Evaluation of the planck mean absorption coefficients for radiation transport through smoke

    Microsoft Academic Search

    John F. Widmann

    2003-01-01

    A literature review of experimental measurements of mass specific extinction coefficients, ? s for combustion-generated particulate has been conducted to obtain an improved value of the constant in the frequently used expression for the Planck mean absorption coefficient through smoke, s m = C 0 f v T . This expression, which results from the product of the spectral absorption

  5. 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.

  6. 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

  7. Optical absorption coefficients in two-dimensional semiconductors under strong magnetic field

    NASA Astrophysics Data System (ADS)

    Yu, L. Y.; Cao, J. C.; Zhang, C.

    2006-06-01

    We calculate the photon absorption coefficient of hot two-dimensional electrons in the presence of a strong magnetic field. The electrons interact strongly with the optical phonons and the acoustic phonons in quantum wells. The dependence of the optical absorption on the magnetic field is obtained by using the quantum mechanical kinetic theory. It is found that the photon absorption spectrum displays a local magnetophonon resonance. The magnetophonon absorption resulting from inelastic scattering between Landau levels is more pronounced at higher temperature. The effect of subband nonparabolicity on the absorption coefficient is also discussed.

  8. Optical absorption coefficients in two-dimensional semiconductors under strong magnetic field

    Microsoft Academic Search

    L. Y. Yu; J. C. Cao; C. Zhang

    2006-01-01

    We calculate the photon absorption coefficient of hot two-dimensional electrons in the presence of a strong magnetic field. The electrons interact strongly with the optical phonons and the acoustic phonons in quantum wells. The dependence of the optical absorption on the magnetic field is obtained by using the quantum mechanical kinetic theory. It is found that the photon absorption spectrum

  9. Extinction coefficients of NO2 and N2O4. [atmospheric solar radiation absorption

    NASA Technical Reports Server (NTRS)

    Bass, A. M.; Ledford, A. E., Jr.; Laufer, A. H.

    1976-01-01

    The extinction coefficient of NO2 has been measured in the spectral range from 185 to 410 nm as a function of temperature between 235 and 298 K. In order to correct for the effect of dimer absorption, the extinction coefficient of N2O4 has also been measured. The effect of a decrease in temperature on NO2 absorption is a reduction in the extinction coefficient of approximately 10% in the range from 320 to 380 nm.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. Optical absorption of pure water in the blue and ultraviolet

    NASA Astrophysics Data System (ADS)

    Lu, Zheng

    The key feature of the Integrating Cavity Absorption Meter (ICAM) is that it produces an isotropic illumination of the liquid sample and thereby dramatically minimizes scattering effects. The ICAM can produce an effective optical path length up to several meters. As a consequence, it is capable of measuring absorption coefficients as low as 0.001 m-1. The early version of the ICAM was used previously to measure the absorption spectrum of pure water over the 380-700 nm range. To extend its range into the ultraviolet, several modifications have been completed. The preliminary tests showed that the modified ICAM was able to measure the absorption of pure water for the wavelength down to 300 nm. After extensive experimental investigation and analysis, we found that the absorption of SpectralonRTM (the highly diffusive and reflective material used to build the ICAM) has a higher impact on measurements of absorption in the UV range than we had expected. Observations of high values for pure water absorption in the UV, specifically between 300 and 360 nm, are a consequence of absorption by the Spectralon RTM. These results indicated that even more serious modifications were required (e.g. SpectralonRTM can not be used for a cavity in the UV). Consequently, we developed a new diffuse reflecting material and used fused silica powder (sub-micron level) sealed inside a quartz cell to replace the inner SpectralonRTM cavity of the ICAM. The new data is in excellent agreement with the Pope and Fry data (380-600 nm) and fills the gap between the 320 nm data of Quickenden and Irvin and 380 nm data of Pope and Fry. We present definitive results for the absorption spectrum of pure water between 300 and 600 nm.

  15. Water-lithium bromide double-effect absorption cooling analysis

    SciTech Connect

    Vliet, G.C.; Lawson, M.B.; Lithgow, R.A.

    1980-12-01

    A numerical model was developed for the transient simulation of the double-effect, water-lithium bromide absorption cooling machine, and the use of the model to determine the effect of the various design and input variables on the absorption unit performance. The performance parameters considered were coefficient of performance and cooling capacity. The sensitivity analysis was performed by selecting a nominal condition and determining performance sensitivity for each variable with others held constant. The variables considered in the study include source hot water, cooling water, and chilled water temperatures; source hot water, cooling water, and chilled water flow rates; solution circulation rate; heat exchanger areas; pressure drop between evaporator and absorber; solution pump characteristics; and refrigerant flow control methods. The performance sensitivity study indicated in particular that the distribution of heat exchanger area among the various (seven) heat exchange components is a very-important design consideration. Moreover, it indicated that the method of flow control of the first effect refrigerant vapor through the second effect is a critical design feature when absorption units operate over a significant range of cooling capacity. The model was used to predict the performance of the Trane absorption unit with fairly good accuracy.

  16. Absolute two-photon absorption coefficients at 355 and 266 nm

    Microsoft Academic Search

    P. Liu; W. L. Smith; H. Lotem; J. H. Bechtel; N. Bloembergen; R. S. Adhav

    1978-01-01

    The absolute two-photon absorption coefficients of uv-transmitting materials have been measured using well-calibrated single picosecond pulses, at the third and fourth harmonic of a mode-locked YAlG:Nd laser system. Two-photon absorption coefficients of the order of 10-3 cm\\/MW were measured for alkali halides, and 10-4 cm\\/MW for harmonic-generating crystals. In materials with band gap greater than 2 ℏ omega, no nonlinear

  17. The absorption coefficient of PbSe\\/CdSe core\\/shell colloidal quantum dots

    Microsoft Academic Search

    Bram de Geyter; Zeger Hens

    2010-01-01

    PbSe\\/CdSe core\\/shell colloidal quantum dots (QDs) are used as a model system to study the absorption coefficient of colloidal QD heterostructures, consisting of at least two semiconductor materials. We show that at energies far above the band gap (3.1 and 3.5 eV) the experimental intrinsic absorption coefficient is in excellent agreement with the Maxwell-Garnett effective medium theory for core\\/shell heterostructures

  18. 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.

  19. 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.

  20. Aerosol Growth and the Condensation Coefficient for Water: A Review

    Microsoft Academic Search

    Michael Mozurkewich

    1986-01-01

    The transfer of gas phase species to aerosols depends critically on the condensation (or sticking) coefficient. Reported values for water on water vary from 0.03 to 1. Theoretical arguments indicate that the condensation coefficient should be near unity for polar species on an aqueous surface. As long as heat transfer is properly accounted for, measurements on bulk water support this

  1. Attenuation coefficients for water quality trading.

    PubMed

    Keller, Arturo A; Chen, Xiaoli; Fox, Jessica; Fulda, Matt; Dorsey, Rebecca; Seapy, Briana; Glenday, Julia; Bray, Erin

    2014-06-17

    Water quality trading has been proposed as a cost-effective approach for reducing nutrient loads through credit generation from agricultural or point source reductions sold to buyers facing costly options. We present a systematic approach to determine attenuation coefficients and their uncertainty. Using a process-based model, we determine attenuation with safety margins at many watersheds for total nitrogen (TN) and total phosphorus (TP) loads as they transport from point of load reduction to the credit buyer. TN and TP in-stream attenuation generally increases with decreasing mean river flow; smaller rivers in the modeled region of the Ohio River Basin had TN attenuation factors per km, including safety margins, of 0.19-1.6%, medium rivers of 0.14-1.2%, large rivers of 0.13-1.1%, and very large rivers of 0.04-0.42%. Attenuation in ditches transporting nutrients from farms to receiving rivers is 0.4%/km for TN, while for TP attenuation in ditches can be up to 2%/km. A 95 percentile safety margin of 30-40% for TN and 6-10% for TP, applied to the attenuation per km factors, was determined from the in-stream sensitivity of load reductions to watershed model parameters. For perspective, over 50 km a 1% per km factor would result in 50% attenuation = 2:1 trading ratio. PMID:24866482

  2. Linear and nonlinear absorption coefficients of spherical two-electron quantum dot

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    In this study, optical properties of two-electron quantum dot confined by an infinite spherical potential surface have been investigated. Linear, nonlinear and total absorption coefficients of S ? P, P ? D and D ? F dipole-allowed transitions between singlet-singlet and triplet-triplet states have been calculated as a function of dot radius and photon energy. The results show that the change of dot radius and incident optical intensity effects the peak positions and amplitudes of linear and nonlinear absorption coefficients. Besides, it has been found that the absorption coefficients of transitions between triplet states are stronger than those of the singlet states, and also triplet absorption transitions occur at higher energies.

  3. Absorptivity of water vapor for 10.6 micron radiation

    NASA Technical Reports Server (NTRS)

    Pugh, E. R.; Krech, R. H.

    1982-01-01

    Attention is called to recent measurements of the absorptivity of water vapor to 10.6-micron laser radiation made using shock-heated H2O/H2 and H2O/Ar mixtures and a probe CO2 laser. It is noted that these measurements give values about a factor of 2 lower than Ludwig's (1971) low resolution values. It is also argued that Fowler's (1981) high values are not likely to be caused by excited water molecules. It is shown that very intense laser radiation would be required to obtain any appreciable vibrational nonequilibrium. Within the narrow spectral range of 944-948/cm, no significant variation in absorption coefficient (suitably normalized) is observed as a function of laser line, water vapor concentration, total pressure, or diluent gas.

  4. Nonlinear absorption coefficient of pulsed laser deposited MgZnO thin film

    NASA Astrophysics Data System (ADS)

    Agrawal, Arpana; Dar, Tanveer A.; Solanki, Ravi; Phase, D. M.; Sen, Pratima

    2015-06-01

    We report the imaginary part of 3rd order nonlinear susceptibility and the nonlinear absorption coefficient of Mg doped ZnO thin film using standard Z-scan technique. The origin of nonlinear absorption is attributed to the two photon absorption followed by the free carrier absorption because of the presence of oxygen vacancy defects. We have also confirmed the experimental results with the theoretical results obtained by considering the steady state response of a two level atom with the monochromatic field models.

  5. Neural network approach to separate the non-algal absorption coefficient into dissolved and particulate

    NASA Astrophysics Data System (ADS)

    Ioannou, Ioannis; Foster, Robert; Gilerson, Alex; Ahmed, Sam

    2013-08-01

    We present a method for the separation of the non-algal absorption coefficient into its independent components of dissolved species and non-algal particulate absorptions from remote sensing reflectance (Rrs) measurements in the visible part of the spectrum. This separation is problematic due to the similar absorption spectra of these substances. Due to this complication, we approach the problem by constructing a neural network which relates the remote sensing reflectance at the available MODIS visible wavelengths (412, 443, 488, 531, 547 and 667nm) with the ratio of the absorption coefficient of non-algal particulates to the absorption coefficient of dissolved species, thereby permitting analytical separation of the total non-algal absorption into particulate and dissolved components. The resulting synthetically trained algorithm is tested on simulated data as well as independently on the NASA Bio-Optical Marine Algorithm Data set (NOMAD). Very good agreement is obtained, with R2 values of 87% and 78% for the non-algal particulate and dissolved absorption components, respectively for the NOMAD. Finally, we apply the algorithm to MODIS data and present global distributions for these parameters.

  6. Intersubband Optical Absorption Coefficients and Refractive Index Changes in a Gaussian Spherical Quantum Dot

    NASA Astrophysics Data System (ADS)

    Ehsanfard, Najmeh; Kazerani Vahdani, Mohammad Reza

    2015-07-01

    The effects of smooth confining potential on the linear and nonlinear optical properties are investigated with Gaussian confining potential in Quantum Dots (GQDs). To this end the effective mass approximation, the compact density matrix approach, and iterative method are used to calculate linear and nonlinear Absorption Coefficient (AC) and Refractive Index (RI) change of an electron confined in GQD. The effects of confining potential and radius of GQD and also incident optical intensity have been investigated. The results show that increasing confining potential decreases the refractive index magnitude and shifts the peak values to the higher energy regions. It is also shown that the peak values of absorption coefficient increase by increasing confining potential. Both absorption coefficient and refractive index experience red shift by increasing the size of quantum dot. It is also shown that transition from step potential to Gaussian potential makes AC and RI to experience a blue shift.

  7. [Spectral absorption properties of the water constituents in the estuary of Zhujiang River].

    PubMed

    Wang, Shan-shan; Wang, Yong-bo; Fu, Qing-hua; Yin, Bin; Li, Yun-mei

    2014-12-01

    Spectral absorption properties of the water constituents is the main factor affecting the light field under the surface of the water and the spectrum above the surface of the water. Thus, the study is useful for understanding of the water spectral property and the remote reversing of water quality parameters. Absorption properties of total suspended particles, non-algal particles, phytoplankton and CDOM were analyzed using the 30 samples collected in July 2013 in the estuary of Zhujiang River. The results indicated that: (1) the non-algal particles absorption dominated the absorption of the total suspended particles; (2) the absorption coefficient of the non-algal particles, which mainly came from the terrigenous deposits, decreased exponentially from short to long wavelength. In addition, the average value and spatial variation of the slope S(d) were higher than those in inland case- II waters; (3) the absorption coefficient of phytoplankton in 440 nm showed a better polynomial relationship with chlorophyll a concentration, while the absorption coefficient of phytoplankton in 675 nm linearly related with the chlorophyll a concentration. Moreover, the influence of accessory pigments on phytoplankton absorption coefficient mainly existed in the range of short wavelength, and Chlorophyll a was the main influencing factor for phytoplankton absorption in long wavelength. The specific absorption coefficient of phytoplankton decreased the power exponentially with the increase of the chlorophyll a concentration; (4) CDOM mainly came from the terrigenous sources and its spectral curve had an absorption shoulder between 250-290 nm. Thus, a piecewise S(g) fitting function could effectively express CDOM absorption properties, i.e., M value and S(g) value in period A (240-260 nm) showed a strong positive correlation. The M value was low, and the humic acid had a high proportion in CDOM; (5) the non-algal particles absorption dominated the total absorption in the estuary of Zhujiang River, and the contribution of the phytoplankton absorption to the total absorption was far lower than that of the non-algal particles. While the contribution of the CDOM was the lowest. The contribution of the CDOM absorption to the total absorption was relatively larger when the content of humic acid was higher. PMID:25826920

  8. Specific absorption coefficient of phytoplankton off the Southwest coast of the Iberian Peninsula: A contribution to algorithm development for ocean colour remote sensing

    NASA Astrophysics Data System (ADS)

    Costa Goela, Priscila; Icely, John; Cristina, Sónia; Newton, Alice; Moore, Gerald; Cordeiro, Clara

    2013-01-01

    The variability in coefficients of absorption for phytoplankton was assessed for an area off the Southwest coast of Portugal. This area included three sites at 2, 10 and 18 km perpendicular to the coast, sampled at surface, mid-Secchi and Secchi depths at each site. Phytoplankton absorption coefficients were transformed into specific coefficients (a*ph(?)) by normalizing them with respect to chlorophyll a (Chla) concentrations determined by High Performance Liquid Chromatography. The influence on the variability of the absorption coefficient of phytoplankton was assessed for physico-chemical and biological parameters such as nutrients or Chla levels, as well as size structure and abundance of the phytoplankton community. The results showed that the phytoplankton absorption coefficients decreased from inshore to offshore, but were relatively constant within the water column, revealing a well-mixed column. The a*ph(?) varied inversely with Chla content, with minima in Autumn and Spring, matching phytoplankton blooms. The effects of the size structure of the community and pigment composition on the variability of phytoplankton absorption coefficient were studied and results showed that size structure had a greater influence on the variability of the phytoplankton absorption, although the pigment contribution was also important.

  9. Corneal-tissue absorption coefficients for 193- and 213-nm ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Pettit, G. H.; Ediger, M. N.

    1996-07-01

    The small-signal absorption coefficients of 193- and 213-nm nanosecond laser pulses in bovine corneal tissue have been studied. The absolute reflectance of a planar quartz-cornea interface was measured at various angles of incidence for low-intensity laser irradiation (i.e., pulse fluences 3 orders of magnitude below the ablation threshold). The reflectance-versus-angle data were analyzed by the use of Fresnel theory to estimate the effective complex index of refraction of the tissue. This analysis indicated corneal absorption coefficients of 39,900 +/- 9800 cm-1 at 193 nm and 21,400 +/- 4900 cm -1 at 213 nm. keratectomy.

  10. Band-edge absorption coefficients from photoluminescence in semiconductor multiple quantum wells

    NASA Technical Reports Server (NTRS)

    Kost, Alan; Zou, Yao; Dapkus, P. D.; Garmire, Elsa; Lee, H. C.

    1989-01-01

    A novel approach to determining absorption coefficients in thin films using luminescence is described. The technique avoids many of the difficulties typically encountered in measurements of thin samples, Fabry-Perot effects, for example, and can be applied to a variety of materials. The absorption edge for GaAs/AlGaAs multiple quantum well structures, with quantum well widths ranging from 54 to 193 A is examined. Urbach (1953) parameters and excitonic linewidths are tabulated.

  11. Spectrum of two-photon absorption coefficient for GaSe

    Microsoft Academic Search

    I. B. Zotova; Y. J. Ding

    2001-01-01

    Summary form only given. The spectrum of the two-photon absorption (TPA) coefficient is crucial for its applications in optical power limiting, autocorrelation, two-photon luminescence, and is important for optical parametric oscillation. GaSe has a large value of second-order nonlinear coefficient and a wide transparency range (0.62-20 ?m) ideal for the efficient generation of mid- and far-IR. The value of the

  12. Intensities and N2 collision-broadening coefficients measured for selected H2O absorption lines between 715 and 732 nm

    NASA Technical Reports Server (NTRS)

    Wilkerson, T. D.; Schwemmer, G.; Gentry, B.; Giver, L. P.

    1979-01-01

    Intensities and N2 collision-broadening coefficients are measured for 62 water vapor absorption lines between 715 and 732 nm potentially applicable to laser remote sensing of atmospheric water vapor. Absolute line strengths and widths were determined from spectra corrected for instrument resolution, air-path absorption and Lorentz and Doppler broadening for pure water vapor and water vapor-nitrogen mixtures in a multipass absorption cell with a base path length of 25 m (White cell). Line strengths are observed to range from 4 x 10 to the -25th to 4 x 10 to the -23rd kayser/molecule per sq cm, and collision broadening coefficients are found to be approximately equal to 0.1 kayser/atm.

  13. 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.

  14. That Bound-Free Absorption Coefficient of the Hydrogen Negative Ion

    Microsoft Academic Search

    S. Geltman

    1962-01-01

    The bound-free absorption coefficient of H⁻ is evaluated by using ; a set of successively improved bound- and freestate wave functions. Better ; agreement with experiment and greater theoretical consistency are shown to result. ; The best theoretical result is tabulated for use in astrophysical applications. ; (auth);

  15. Absorption Coefficients for the Wings of the First Two Resonance Doublets of Cesium Broadened by Argon

    Microsoft Academic Search

    C. L. Chen; A. V. Phelps

    1973-01-01

    Measurements are reported of the absolute absorption coefficients in the wings of the 8944-, 8521-, 4593-, and 4555-Å resonance lines of cesium in the presence of argon at densities between about 6 × 1018 and 2 × 1019 atom cm-3. The data extend from about 0.7 Å to as much as 600 Å from the line center and were obtained

  16. Measurements of continuous spectra of atmospheric absorption coefficients from UV to NIR via optical method

    Microsoft Academic Search

    S. Mogo; V. E. Cachorro; M. Sorribas; A. de Frutos; R. Fernández

    2005-01-01

    In this study we extend from the visible to the UV a traditional method for studying the radiative properties of black carbon. We apply this measuring possibility to a practical study carried out in the Southern Iberian Peninsula during summer 2004. Using an optical technique based on the integrating sphere method, absorption coefficients, sigmaa, were determined in the visible and

  17. Measurements of continuous spectra of atmospheric absorption coefficients from UV to NIR via optical method

    Microsoft Academic Search

    S. Mogo; V. E. Cachorro; M. Sorribas; A. de Frutos; R. Fernández

    2005-01-01

    In this study we extend from the visible to the UV a traditional method for studying the radiative properties of black carbon. We apply this measuring possibility to a practical study carried out in the Southern Iberian Peninsula during summer 2004. Using an optical technique based on the integrating sphere method, absorption coefficients, ?a, were determined in the visible and

  18. Quantitative photoacoustic microscopy of optical absorption coefficients from acoustic spectra in the optical diffusive regime

    PubMed Central

    Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V.

    2012-01-01

    Abstract. Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed. PMID:22734767

  19. Absorption of water-soluble vitamins.

    PubMed

    Halsted, Charles H

    2003-03-01

    Water-soluble vitamins are required as enzyme cofactors in a wide variety of metabolic reactions. Riboflavin, niacin, and vitamin C are essential in redox reactions; thiamine and biotin are involved in macronutrient metabolism; and folate, vitamin B12, pyridoxine, and riboflavin play important roles in the regulation of S-adenosylmethionine production and DNA synthesis. Each of the water-soluble vitamins appears to require its own membrane transport process for absorption across the enterocyte. The absorption of vitamin B12, or cobalamin (Cbl), is unique in requiring multiple processes from the stomach to the ileum that involve at least four different binding proteins. Whereas all water-soluble vitamins are absorbed from the small intestine, folate, biotin, and riboflavin can be transported across colonic epithelial cells, with uncertain clinical significance. This article reviews recent studies on the requirement, metabolism, and deficiency state of each water-soluble vitamin, followed by a discussion of current knowledge on the regulation of its intestinal absorption. PMID:15703550

  20. Effects of combined scattering and absorption coefficients on laser speckle contrast imaging values

    NASA Astrophysics Data System (ADS)

    Khaksari, Kosar; Kirkpatrick, Sean J.

    2015-03-01

    Laser Speckle contrast imaging (LSCI) is a non-invasive or minimally invasive method for visualizing blood flow and perfusion in biological tissues. In LSCI the motion of scattering particles results in a reduction in global and regional speckle contrast. A variety of parameters can affect the calculated contrast values in LSCI techniques, including the optical properties of the fluid and surrounding tissue. In typical LSCI where the motion of blood is of interests, optical properties are influenced by hematocrit levels. In this work we considered the combined effects of both the scattering and absorption coefficients on LSCI measurements on a flow phantom. Fluid phantoms consisting of various concentrations of neutrally buoyant ~10 micron microspheres and India ink mixed with DI water were formulated to mimic the optical properties of whole blood with various levels of hematocrit. In these flow studies, it was found that an increase in ?a and/or ?s led to a decrease in contrast values when all other experimental parameters were held constant. The observed reduction in contrast due to optical property changes could easily be confused with a contrast reduction due to increased flow velocity. These results suggest that optical properties need to be considered when using LSCI to make flow estimates.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. AN INTERCOMPARISON CF THE INTEGRATING PLATE AND THE LASER TRANSMISSION METHODS FOR DETERMINATION OF AEROSOL ABSORPTION COEFFICIENTS

    SciTech Connect

    Sadler, M.; Charlson, R.J.; Rosen, H.; Novakov, T.

    1980-07-01

    The absorption coefficients determined by the integrating plate method and the laser transmission method are found to be comparable and highly correlated. Furthermore, a high correlation is found between these absorption coefficients and the carbon content of the aerosol in urbanized regions.

  6. Absorption coefficients and mass concentrations of the urban aerosol of Vienna, Austria, during the years 1985 and 1986

    Microsoft Academic Search

    Regina M. Hitzenberger

    1993-01-01

    Nearly every day aerosol absorption coefficients and mass concentrations were measured at the physics building of the University of Vienna, located approximately 1.5 km from the city center. The aerosol was deposited on Nuclepore filters with 0.2 µm pore size, which were analyzed both gravimetrically for mass concentration cm and by the integrating plate method for absorption coefficients (sa). The

  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. 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

  9. The measurement of the diffusion coefficient of water in paints and polymers from their swelling by using an interferometric technique

    Microsoft Academic Search

    E. L. J. Goossens; A. J. J. van der Zanden; H. L. M. Wijen; W. H. van der Spoel

    2003-01-01

    An interferometric technique has been used to measure the swelling of a paint film caused by its absorption of water vapour. The diffusion coefficient of water in paint is obtained from the time evolution of the thickness of the paint film, when the paint film is subjected to an almost stepwise change in the relative humidity of the surrounding air.

  10. 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

  11. Consumptive Water Use and Crop Coefficients of Irrigated Sunflower

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In semi-arid environments, the use of irrigation is necessary for sunflower production to reach its maximum potential. The aim of this study was to quantify the consumptive water use and crop coefficients of irrigated sunflower (Helianthus annuus L.) without soil water limitations during two growing...

  12. n-Alcohol/Water Partition Coefficients for Decachlorobiphenyl (PCB 209)

    EPA Science Inventory

    Measurements of n-octanol/water partition coefficients (Kow) for highly hydrophobic chemicals are extremely difficult and are rarely made, in part due to the large volumes of water typically needed to quantify these compounds in the aqueous phase. An extrapolation approach using ...

  13. Effective infrared absorption coefficient for photothermal radiometric measurements in biological tissues.

    PubMed

    Majaron, Boris; Milanic, Matija

    2008-01-01

    Although photothermal radiometric (PTR) measurements commonly employ broad-band signal acquisition to increase the signal-to-noise ratio, all reported studies apply a fixed infrared (IR) absorption coefficient to simplify the involved signal analysis. In samples with large spectral variation of micro(lambda) in mid-IR, which includes most biological tissues, the selection of the effective IR absorption coefficient value (micro(eff)) can strongly affect the accuracy of the result. We present a novel analytical approach for the determination of optimal micro(eff) from spectral properties of the sample and radiation detector. In extensive numerical simulations of pulsed PTR temperature profiling in human skin using three common IR radiation detectors and several acquisition spectral bands, we demonstrate that our approach produces viable values micro(eff). Two previously used analytical estimations perform much worse in the same comparison. PMID:18182701

  14. The absorption coefficient of PbSe/CdSe core/shell colloidal quantum dots

    NASA Astrophysics Data System (ADS)

    De Geyter, Bram; Hens, Zeger

    2010-10-01

    PbSe/CdSe core/shell colloidal quantum dots (QDs) are used as a model system to study the absorption coefficient of colloidal QD heterostructures, consisting of at least two semiconductor materials. We show that at energies far above the band gap (3.1 and 3.5 eV) the experimental intrinsic absorption coefficient is in excellent agreement with the Maxwell-Garnett effective medium theory for core/shell heterostructures and bulk values for the dielectric function. This allows for a straightforward measurement of the QD concentration from the absorbance spectrum. It also implies that basic optical measurements on core/shell heterostructures, such as measurements of the oscillator strength and photoluminescence lifetime, can be corrected for the local field reduction in QD heterostructures.

  15. A Convolution Algorithm of Differential Coefficients of liquid water Based on Vibrational Raman Scattering

    NASA Astrophysics Data System (ADS)

    Han, Dong; Chen, Liangfu; Tao, Jinhua; Su, Lin; Li, Shenshen; Yu, Chao; Yan, Huanhuan

    Inelastic Vibrational Raman Scattering (VRS) by liquid water is one significant limitation to the accuracy of the retrieval of trace gas constituents in atmosphere over waters, particularly over clear ocean waters, while using satellite data with Differential Optical Absorption Spec-troscopy technique (DOAS).The effect which is similar to the Ring effect in atmosphere results in the filling in of Fraunhofer lines, which is known as solar absorption lines. The inelastic component of the liquid water scattering causes a net increase of radiance in the line because more radiation is shifted to the wavelength of an absorption line than shifted from this wave-length to other wavelengths. The spectrum at the top of the atmosphere over land measured by OMI (Ozone Monitoring Instrument)/AURA is convolved with Vibrational Raman Scat-tering coefficients of liquid water, divided by the original measured spectrum, with a cubic polynomial subtracted off, to create differential water Ring spectrum. The OMI spectrum over land is chosen to avoid the effect of VRS by liquid water. This method has been suggested in order to obtain an effective differential water Ring coeffients for the DOAS fitting process.The differential water Ring spectrum could be used to improve the accuracy of the retrieval of the trace gases concentration. The method is not relying on RTM, which would be time-consuming and depending on lot of parameters. Therefore, it is very fast and convenient.

  16. 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

  17. CO2 absorption coefficients at high pressure and high temperature: measures and model

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Tran, H.; Politi, R.; Grassi, D.; Adriani, A.

    2012-09-01

    In this work we present the CO2 experimental absorption coefficients recorded at the same conditions found in the deep atmosphere of Venus. Measurements were done according to a real vertical profile, varying the pressure from 1 to 30 bar and the temperature from 298 to 600 K. Each spectrum was acquired with a resolution of 2 cm-1. The data has been compared with synthetic spectra obtained by taking into account the line mixing effect.

  18. Absorption\\/scattering coefficients and scattering phase functions in reticulated porous ceramics

    Microsoft Academic Search

    T. J. Hendricks; J. R. Howell

    1996-01-01

    Spectral absorption and scattering coefficients and spectral phase functions have been derived for partially stabilized zirconia (PS ZrOâ) and oxide-bonded silicon carbide (OB SiC) reticulated porous ceramics (RPCs) across the wavelength range 0.4 - 5.0 μm. These spectral radiative properties were investigated and quantified for 10 ppi (pores\\/inch), 20 ppi, and 65 ppi materials. Radiative properties were recovered from spectral

  19. Methane absorption coefficients for the jovian planets from laboratory, Huygens, and HST data

    NASA Astrophysics Data System (ADS)

    Karkoschka, Erich; Tomasko, Martin G.

    2010-02-01

    We use 11 data sets of methane transmission measurements within 0.4-5.5 ?m wavelength to model the methane transmission for temperature and pressure conditions in the jovian planets. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methane absorption inside Titan's atmosphere ( Tomasko et al., 2008b, PSS 56, 624), and we provide a refined analysis. The last data set is a set of new Jupiter images by the Hubble Space Telescope to measure atmospheric transmission with Ganymede as the light source. Below 1000 nm wavelength, our resulting methane absorption coefficients are generally close to those by Karkoschka (1998, Icarus 133, 134), but we add descriptions of temperature and pressure dependence. One remaining inconsistency occurs between 882 and 902 nm wavelength where laboratory data predict larger absorptions in the jovian atmospheres than observed. We present possible explanations. Above 1000 nm, our analysis of the Huygens data confirms methane absorption coefficients by Irwin et al. (2006, Icarus 181, 309) at their laboratory temperatures. Huygens data also confirm Irwin's model of extrapolation to Titan's lower pressures. However, their model of extrapolation to Titan's lower temperatures predicts absorption coefficients up to 100 times lower than measured by Huygens. For each of ˜3700 wavelengths, we present a temperature dependence that is consistent with all laboratory data and the Huygens data. Since the Huygens data probe similar temperatures as many observations of Saturn, Uranus, Neptune, and Titan, our methane model will allow more reliable radiative transfer models for their atmospheres.

  20. Americium speciation and distribution coefficients in a granitic ground water

    SciTech Connect

    Beall, G.W.; Lee, W.W.L.; Van Luik, A.E.

    1986-01-01

    The possible importance of pH-dependent speciation in determining the distribution coefficient of americium in a granitic ground water is discussed. The authors obtained experimental distribution coefficients for americium. The authors used the geochemical code PHREEQE to calculate the amount present of americium complexes with hydroxides and carbonates over a range of pH, using formation constants taken from the literature and one estimated for AmOHCO/sub 3/, a neutral complex suspected of playing an important role in the aqueous chemistry of americium, although not experimentally evaluated. Combining the above inputs, the authors calculated individual distribution coefficients for americium complexes. The authors are able to show that the batch distribution coefficient for americium can be seen as the sum of individual distribution coefficients of various complexes.

  1. Use of radial symmetry for the calculation of cylindrical absorption coefficients and optimal capillary loadings

    DOE PAGESBeta

    Khalifah, Peter

    2015-02-01

    The problem of numerically evaluating absorption correction factors for cylindrical samples has been revisited using a treatment that fully takes advantage of the sample symmetry. It is shown that the path lengths for all points within the sample at all possible diffraction angles can be trivially determined once the angle-dependent distance distribution for a single line of points is calculated. This provides advantages in both computational efficiency and in gaining an intuitive understanding of the effects of absorption on diffraction data. A matrix of absorption coefficients calculated for µR products between 0 and 20 for diffraction angles ?D of 0°more »to 90° were used to examine the influence of (1) capillary diameter and of (2) sample density on the overall scattered intensity as a function of diffraction angle, where µ is the linear absorption coefficient for the sample and R is the capillary radius. Based on this analysis, the optimal sample loading for a capillary experiment to maximize diffraction at angles of 0 – 50° is in general expected to be achieved when the maximum radius capillary compatible with the beam is used, and when the sample density is adjusted to be 3/(4µR) of its original density.« less

  2. 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.

  3. Use of radial symmetry for the calculation of cylindrical absorption coefficients and optimal capillary loadings

    DOE PAGESBeta

    Khalifah, Peter [Stony Brook Univ., NY (United States); Brookhaven National Lab., Upton, NY (United States)

    2015-02-01

    The problem of numerically evaluating absorption correction factors for cylindrical samples has been revisited using a treatment that fully takes advantage of the sample symmetry. It is shown that the path lengths for all points within the sample at all possible diffraction angles can be trivially determined once the angle-dependent distance distribution for a single line of points is calculated. This provides advantages in both computational efficiency and in gaining an intuitive understanding of the effects of absorption on diffraction data. A matrix of absorption coefficients calculated for µR products between 0 and 20 for diffraction angles ?D of 0° to 90° were used to examine the influence of (1) capillary diameter and of (2) sample density on the overall scattered intensity as a function of diffraction angle, where µ is the linear absorption coefficient for the sample and R is the capillary radius. Based on this analysis, the optimal sample loading for a capillary experiment to maximize diffraction at angles of 0 – 50° is in general expected to be achieved when the maximum radius capillary compatible with the beam is used, and when the sample density is adjusted to be 3/(4µR) of its original density.

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

    Microsoft Academic Search

    Thana Phuphuakrat; Tomoaki Namioka; Kunio Yoshikawa

    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

  5. SOIL MOISTURE AND ABSORPTION OF WATER BY TREE ROOTS1

    Microsoft Academic Search

    T. T. Kozlowski

    1987-01-01

    Shade trees undergo periodic dehydration because the rate of absorption of soil water lags behind the rate of transpirational water loss from tree crowns. The rate of absorption of water from wet, warm, and well-aerated soil is controlled largely by the rate of transpiration . However, ab- sorption of water often is impeded by low soil moisture con- tent, a

  6. Near-infrared studies of glucose and sucrose in aqueous solutions: water displacement effect and red shift in water absorption from water-solute interaction

    E-print Network

    Jung, Youngeui

    2013-01-01

    We use near infrared spectroscopy to obtain concentration dependent glucose absorption spectra in their aqueous solutions in the near-infrared range (3800 - 7500 cm^{-1}). We introduce a new method to obtain reliable glucose absorption bands from aqueous glucose solutions without measuring the water displacement coefficients of glucose separately. Additionally, we are able to extract the water displacement coefficients of glucose, and this may give a new general method using spectroscopy techniques applicable to other water soluble materials. We also observe red shifts in the absorption bands of water in the hydration shell around solute molecules, which comes from contribution of the interacting water molecules around the glucose molecules in solutions. The intensity of the red shift get larger as the concentration increases, which indicates that as the concentration increases more water molecules are involved in the interaction. However, the red shift in frequency does not seem to depend significantly on th...

  7. 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.

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

    PubMed

    Johansson, Johannes D

    2010-01-01

    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. PMID:21054121

  10. Infinite dilution activity coefficients and Henry's law coefficients of some priority water pollutants determined by a relative gas chromatographic method

    SciTech Connect

    Tse, G.; Orbey, H.; Sandler, S.I. (Univ. of Delaware, Newark, DE (United States))

    1992-10-01

    A simple, fast relative measurement method based on gas chromatography developed recently has been used to determine the infinite dilution activity coefficients and Henry's law coefficients in water of some priority pollutants. The authors show that this simple method can be used to obtain accurate data quite rapidly, which is especially valuable for screening studies. Further, the infinite dilution activity coefficient and Henry's law coefficient data reported here can be useful for directly estimating environmentally important properties such as solubilities in water, multimedia partitioning, and octanol-water partition coefficients. 8 refs., 1 tab.

  11. Measurements of the absorption and scattering coefficients of aerosol particles in suburb of Nanjing (China)

    NASA Astrophysics Data System (ADS)

    Yin, Yan; Chen, Yu; Wang, Weiwei; Yan, Jiade; Qian, Ling; Tong, Yaoqing; Lin, Zhenyi

    2008-08-01

    The absorption and scattering coefficients of atmospheric aerosols were continuously measured with a Photoacoustic Soot Spectrometer (PASS, DMT Inc. USA) at a suburb site of Nanjing, one of the regions experiencing rapid industrialization in China. The measurements were carried out during autumn and winter 2007. A preliminary analysis of the data shows that, the scattering coefficient, Bscat, is two to ten times larger than the absorption coefficient, Babs, implying that the aerosols formed/emitted in this area are more scattering than previous assumed, and can be more important in cooling the Earth-atmosphere system. The results also indicate that the absolute values of both parameters are very much dependent on the meteorological conditions, such as wind speed and direction, fog, rain, etc. as well as the time of the day. Higher values often appear at nighttimes when wind is weak, especially when a temperature inverse layer is present near the surface. Higher values of Bscat and Babs were also observed under hazy and foggy weather conditions or when wind is blown from east, where a large industrial zone is located. Simultaneous measurements of the number concentrations, chemical compositions, and size distributions of aerosol particles are used to explain the characteristics of the changes in Bscat and Babs.

  12. 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.

  13. 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

  14. 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

  15. Optical absorption of pure water in the blue and ultraviolet

    Microsoft Academic Search

    Zheng Lu

    2006-01-01

    The key feature of the Integrating Cavity Absorption Meter (ICAM) is that it produces an isotropic illumination of the liquid sample and thereby dramatically minimizes scattering effects. The ICAM can produce an effective optical path length up to several meters. As a consequence, it is capable of measuring absorption coefficients as low as 0.001 m-1. The early version of the

  16. Statistical Estimation of the Atmospheric Aerosol Absorption Coefficient Based on the Data of Optical Measurements

    SciTech Connect

    Uzhegov, V.N.; Kozlov, V.S.; Panchenko, M.V.; Pkhalagov, Yu.A.; Pol'kin, V.V.; Terpugova, S.A.; Shmargunov, V.P.; Yausheva, E.P.

    2005-03-18

    The problem of the choice of the aerosol optical constants and, in particular, imaginary part of the refractive index of particles in visible and infrared (IR) wavelength ranges is very important for calculation of the global albedo of the atmosphere in climatic models. The available models of the aerosol optical constants obtained for the prescribed chemical composition of particles (see, for example, Ivlev et al. 1973; Ivlev 1982; Volz 1972), often are far from real aerosol. It is shown in (Krekov et al. 1982) that model estimates of the optical characteristics of the atmosphere depending on the correctness of real and imaginary parts of the aerosol complex refractive index can differ by some hundreds percent. It is known that the aerosol extinction coefficient {alpha}({lambda}) obtained from measurements on a long horizontal path can be represented as {alpha}({lambda})={sigma}({lambda})+{beta}({lambda}), where {sigma} is the directed light scattering coefficient, and {beta} is the aerosol absorption coefficient. The coefficient {sigma}({lambda}) is measured by means of a nephelometer. Seemingly, if measure the values {alpha}({lambda}) and {sigma}({lambda}), it is easy to determine the value {beta}({lambda}). However, in practice it is almost impossible for a number of reasons. Firstly, the real values {alpha}({lambda}) and {sigma}({lambda}) are very close to each other, and the estimate of the parameter {beta}({lambda}) is concealed by the errors of measurements. Secondly, the aerosol optical characteristics on the long path and in the local volume of nephelometer can be different, that also leads to the errors in estimating {beta}({lambda}). Besides, there are serious difficulties in performing spectral measurements of {sigma}({lambda}) in infrared wavelength range. Taking into account these circumstances, in this paper we consider the statistical technique, which makes it possible to estimate the absorption coefficient of real aerosol on the basis of analysis of simultaneous measurements of the spectral aerosol extinction coefficients {alpha}({lambda}), the directed scattering coefficient of dry aerosol {sigma}{sub 0}(0.55) and the mass concentration of aerosol containing BC (black carbon) Ms.

  17. 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

  18. Estimation of sieving coefficients of convective absorption of drugs in perfused rat jejunum.

    PubMed

    Leahy, D E; Lynch, J; Finney, R E; Taylor, D C

    1994-10-01

    Intestinal absorption of many hydrophilic drugs cannot be explained solely in terms of pH-partition and solvent-drag effects have been described in a number of cases. However, quantitative estimates of sieving coefficient (phi) for drug molecules have tended to be variable. In the present work an in situ perfused intestinal loop preparation in the rat has been used to measure the disappearance of five hydrophilic drugs from the intestinal lumen and a mathematical model of drug absorption in the presence of net and unidirectional fluid fluxes has been developed. The model allows separate estimation of the convective (solvent drag) and nonconvective (partition) components of drug absorption from the experimental data. The five drugs studied were found to have phi values ranging from 0.1-0.9; this was highly dependent on molecular size. Analysis of the data shows that three of the drugs are absorbed almost exclusively by the convective process (caffeine, cimetidine, hydrochlorthiazide) while the other two are absorbed by both convective and nonconvective processes (salicylate, oxprenolol). We conclude that the methodology is a useful and reliable means of deriving separate estimates of these two components of drug absorption. PMID:7791039

  19. Aqueous Solubilities, Infinite Dilution Activity Coefficients and Octanol–Water Partition Coefficients of Tricyclic Analogs of Acyclovir

    Microsoft Academic Search

    W. Zielenkiewicz; B. Golankiewicz; G. L. Perlovich; M. Ko?bia?

    1999-01-01

    Solubilities of tricyclic analogs of acyclovir have been determined in water at 25, 35, and 45°C and in octanol, water-saturated octanol, and octanol-saturated water at 25°C. Octanol-water partition coefficients were determined at 25°C. Melting temperatures and molar enthalpies of fusion were measured. Activity coefficients in water, octanol, and in aqueous octanol solutions were determined and are discussed. The effect of

  20. The coefficient of bond thermal expansion measured by extended x-ray absorption fine structure

    NASA Astrophysics Data System (ADS)

    Fornasini, P.; Grisenti, R.

    2014-10-01

    The bond thermal expansion is in principle different from the lattice expansion and can be measured by correlation sensitive probes such as extended x-ray absorption fine structure (EXAFS) and diffuse scattering. The temperature dependence of the coefficient ?bond(T) of bond thermal expansion has been obtained from EXAFS for CdTe and for Cu. A coefficient ?tens(T) of negative expansion due to tension effects has been calculated from the comparison of bond and lattice expansions. Negative lattice expansion is present in temperature intervals where ?bond prevails over ?tens; this real-space approach is complementary but not equivalent to the Grüneisen theory. The relevance of taking into account the asymmetry of the nearest-neighbours distribution of distances in order to get reliable bond expansion values and the physical meaning of the third cumulant are thoroughly discussed.

  1. 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.

  2. A reduced-scale railway noise barrier's insertion loss and absorption coefficients: comparison of field measurements and predictions

    Microsoft Academic Search

    T. A. Busch; R. E. Nugent

    2003-01-01

    In situ testing determined the insertion loss (IL) and absorption coefficients of a candidate absorptive noise barrier (soundwall) to abate railway noise for residents of Anaheim, CA. A 4000m barrier is proposed south of the tracks, but residential areas to the north have expressed concerns that barrier reflections will increase their noise exposure. To address these concerns, a 3.66m high

  3. Effect of the absorption coefficient of aluminium plates on their thermoelastic bending in photoacoustic experiments

    NASA Astrophysics Data System (ADS)

    Markushev, D. D.; Ordonez-Miranda, J.; Rabasovi?, M. D.; Galovi?, S.; Todorovi?, D. M.; Bialkowski, S. E.

    2015-06-01

    The open-cell photoacoustic signal measured in the transmission configuration for aluminum thin plates with thicknesses of 280 ?m, 197 ?m, and 112 ?m is experimentally and theoretically analyzed, in the 20 Hz-7 kHz modulation frequency range. It is shown that the observed differences between the predictions of the standard thermoelastic model and the experiment data of both the amplitude and phase of the photoacoustic signal can be overcome by considering the aluminum samples coated with a thin layer of black paint as volume-absorber materials. This new approach provides a quite good agreement with the obtained experimental data, in the whole frequency range, and yields an effective absorption coefficient of (16 ± 2) mm-1, for a 280 ?m-thick sample. The introduction of the finite absorption coefficient led to the correct ratio between the thermal diffusion and thermoelastic components of the photoacoustic signal. Furthermore, it is found that the "volume-absorber" approach accurately describes the behavior of the amplitude, but not that of the phase recorded for a 112 ?m-thick sample, due to its relatively strong thermoelastic bending, which is not considered by this theory. Within the approximation of the small bending, the proposed "volume-absorber" model provides a reliable description of the photoacoustic signal for Al samples thicker than 112 ?m, and extends the applicability of the classical "opaque" approach.

  4. Diurnal Variations in the Specific Absorption Coefficient: Recent Results from Mexico City

    NASA Astrophysics Data System (ADS)

    Baumgardner, D.; Kok, G.; Raga, G. B.

    2005-12-01

    The specific absorption coefficient, ?a, defined as the absorbance of light per unit path length and per unit of mass concentration, is an important, radiative property of the atmosphere and is also used as a conversion factor when estimating the mass of light absorbing material, usually black carbon, from measurements of the absorption coefficient. The magnitude of ?a varies over a wide range of values, 2 to 25 m 2g-1, due to the composition and structure of the light absorbing material. The value of this parameter is usually determined by measuring the absorption coefficient, Babs with a Particle Soot Absorption Photometer (PSAP) or an Aethalometer and the black carbon (BC) with one of several types of thermal optical techniques. There are two disadvantages to this approach, both associated with the thermo-optical derivations of BC. The first disadvantage is that significant sample times are needed to accumulate sufficient aerosol mass to derive the BC value. Secondly, there is a large uncertainty associated with the BC mass derived from the thermo-optical method. The recent development of the Single Particle Soot Photometer (SP-2) has allowed high resolution estimates of ?a . The SP2 measures directly the mass of single, light absorbing particles using laser induced incandescence. This mass, when combined with Babs derived from measurements of light attenuation, leads to an accurate, fast response estimate of ?a . This technique has been recently applied during a field campaign in Mexico City in April, 2005. An SP-2, PSAP, Nephelometer, and other particle counters measured the physical and optical properties of particles in the southwest sector of Mexico City. Measurements were made 24 hours a day so that the diurnal variations could be monitored. The value of ?a, derived every five minutes from the measurements of the SP-2 and PSAP, showed clear diurnal variations that reflect the changes in the age of the BC that is emitted by local sources. In the morning the BC is fresh as a result of the peak in traffic and ages with time as the boundary layer develop and photochemical processes presumably alter the characteristics of the BC.

  5. Water vapor spectroscopy in the 815-nm wavelength region for Differential Absorption Lidar measurements

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Browell, Edward V.

    1995-01-01

    The differential absorption lidar (DIAL) technique was first applied to the remote measurement of atmospheric water vapor profiles from airborne platforms in 1981. The successful interpretation of the lidar profiles relies strongly on an accurate knowledge of specific water vapor absorption line parameters: line strength, pressure broadening coefficient, pressure-induced shift coefficient and the respective temperature-dependence factors. NASA Langley Research Center has developed and is currently testing an autonomous airborne water vapor lidar system: LASE (Lidar Atmospheric Sensing Experiment). This DIAL system uses a Nd:YAG-pumped Ti:Sapphire laser seeded by a diode laser as a lidar transmitter. The tunable diode has been selected to operate in the 813-818 nm wavelength region. This 5-nm spectral interval offers a large distribution of strengths for temperature-insensitive water vapor absorption lines. In support of the LASE project, a series of spectroscopic measurements were conducted for the 16 absorption lines that have been identified for use in the LASE measurements. Prior to this work, the experimental data for this water vapor absorption band were limited - to our knowledge - to the line strengths and to the line positions.

  6. 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

  7. Experimental investigation of X-ray spectral absorption coefficients in heated Al and Ge on the Iskra-5 laser facility

    SciTech Connect

    Bondarenko, S V; Garanin, Sergey G; Zhidkov, N V; Pinegin, A V; Suslov, N A [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

    2012-01-31

    We set forth the data of experimental investigation of X-ray spectral absorption coefficients in the 1.1 - 1.6 keV photon energy range for Al and Ge specimens bulk heated by soft X-ray radiation. Two experimental techniques are described: with the use of one facility channel and the heating of specimens by the X-ray radiation from a plane burnthrough target, as well as with the use of four channels and the heating by the radiation from two cylindrical targets with internal input of laser radiation. The X-ray radiation absorption coefficients were studied by way of transmission absorption spectroscopy using backlighting X-ray radiation from a point source. The results of investigation of X-ray spectral absorption coefficients on the 1s - 2p transitions in Al atoms and the 2p - 3d transitions in Ge atoms are presented.

  8. Impact of new water vapor continuum coefficients in the far infrared on atmospheric fluxes and cooling rates

    NASA Astrophysics Data System (ADS)

    Masiello, G.; Serio, C.; Esposito, F.; Di Girolamo, P.; Palchetti, L.

    2009-03-01

    The paper illustrates the impact of new water vapor continuum coefficients in the far infrared on spectral cooling rates and integrated atmospheric fluxes. The analysis has been based on data and results obtained within the ECOWAR project (Earth Cooling by Water vapor Radiation). A novel methodology has been developed, implemented and used to retrieve foreign-broadened water vapor continuum absorption coefficients from atmospheric emitted spectral radiance observations in the spectral range 240 to 590 cm?1. The impact of these new coefficients on spectral cooling rates has been assessed. The new coefficients show that the lower troposphere tends to cool down at a rate larger than that predicted by the state-of-art Mlawer, Tobin-Clough, Kneizys, Davies (MT_CKD) continuum.

  9. 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 ...

  10. Air sparging: Prediction of air-water mass transfer coefficients

    SciTech Connect

    Braida, W.J.; Ong, S.K.

    1998-07-01

    One of the difficulties with the application of air sparging as a remedial technology is that not much is known about the physical-chemical processes during air sparging. This study presents information on the air-water mass transfer of volatile organic compounds (VOCs) under air sparged conditions. The mass transfer coefficients were estimated using a single air channel experimental setup, where a thin channel of air (approx. 1.5 mm) was allowed to flow over saturated VOC-contaminated soil. The experimental setup allowed VOC concentrations in both liquid and gas phases to be measured. Eleven VOCs and three different porous media with mean particle size 0.168 mm, 0.190 mm, and 0.305 mm were used in the experiments. Air velocities ranged between 0.2 cm/s and 2.5 cm/s. Air-water mass transfer coefficients were estimated by fitting experimental data with an advection-diffusion model. The model assumed the existence of an aqueous phase influence zone (called the mass transfer zone (MTZ)) surrounding the air channel in which VOCs present were directly impacted by the air flow. The size of the influence zone was found to be a function of the physical-chemical characteristics of the porous media and the VOCs. The estimated liquid side lumped air-water mass transfer coefficients (K{sub L}a) were found to range from 2.6 x 10{sup {minus}5} to 2.4 x 10{sup {minus}4} min{sup {minus}1}. An empirical model was developed by correlating the modified Sherwood number with the air phase Peclet number. Henry's law constant, normalized particle size, and uniformity coefficient of the porous media.

  11. 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

  12. 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.

  13. Water-lithium bromide double-effect absorption cooling analysis. Final report

    SciTech Connect

    Vliet, G.C.; Lawson, M.B.; Lithgow, R.A.

    1980-12-01

    This investigation involved the development of a numerical model for the transient simulation of the double-effect, water-lithium bromide absorption cooling machine, and the use of the model to determine the effect of the various design and input variables on the absorption unit performance. The performance parameters considered were coefficient of performance and cooling capacity. The sensitivity analysis was performed by selecting a nominal condition and determining performance sensitivity for each variable with others held constant. The variables considered in the study include source hot water, cooling water, and chilled water temperatures; source hot water, cooling water, and chilled water flow rates; solution circulation rate; heat exchanger areas; pressure drop between evaporator and absorber; solution pump characteristics; and refrigerant flow control methods. The performance sensitivity study indicated in particular that the distribution of heat exchanger area among the various (seven) heat exchange components is a very important design consideration. Moreover, it indicated that the method of flow control of the first effect refrigerant vapor through the second effect is a critical design feature when absorption units operate over a significant range of cooling capacity. The model was used to predict the performance of the Trane absorption unit with fairly good accuracy. The dynamic model should be valuable as a design tool for developing new absorption machines or modifying current machines to make them optimal based on current and future energy costs.

  14. 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.

  15. Integrating sphere-based photoacoustic setup for simultaneous absorption coefficient and Grüneisen parameter measurements of biomedical liquids

    NASA Astrophysics Data System (ADS)

    Villanueva, Yolanda; Hondebrink, Erwin; Petersen, Wilma; Steenbergen, Wiendelt

    2015-03-01

    A method for simultaneously measuring the absorption coefficient ?a and Grüneisen parameter ? of biological absorbers in photoacoustics is designed and implemented using a coupled-integrating sphere system. A soft transparent tube with inner diameter of 0.58mm is used to mount the liquid absorbing sample horizontally through the cavity of two similar and adjacent integrating spheres. One sphere is used for measuring the sample's ?a using a continuous halogen light source and a spectrometer fiber coupled to the input and output ports, respectively. The other sphere is used for simultaneous photoacoustic measurement of the sample's ? using an incident pulsed light with wavelength of 750nm and a flat transducer with central frequency of 5MHz. Absolute optical energy and pressure measurements are not necessary. However, the derived equations for determining the sample's ?a and ? require calibration of the setup using aqueous ink dilutions. Initial measurements are done with biological samples relevant to biomedical imaging such as human whole blood, joint and cyst fluids. Absorption of joint and cyst fluids is enhanced using a contrast agent like aqueous indocyanine green dye solution. For blood sample, measured values of ?a = 0.580 +/- 0.016 mm-1 and ? = 0.166 +/- 0.006 are within the range of values reported in literature. Measurements with the absorbing joint and cyst fluid samples give ? values close to 0.12, which is similar to that of water and plasma.

  16. Spatially resolved absolute diffuse reflectance measurements for noninvasive determination of the optical scattering and absorption coefficients of biological tissue

    NASA Astrophysics Data System (ADS)

    Kienle, Alwin; Lilge, Lothar; Patterson, Michael S.; Hibst, Raimund; Steiner, Rudolf; Wilson, Brian C.

    1996-05-01

    The absorption and transport scattering coefficients of biological tissues determine the radial dependence of the diffuse reflectance that is due to a point source. A system is described for making remote measurements of spatially resolved absolute diffuse reflectance and hence noninvasive, noncontact estimates of the tissue optical properties. The system incorporated a laser source and a CCD camera. Deflection of the incident beam into the camera allowed characterization of the source for absolute reflectance measurements. It is shown that an often used solution of the diffusion equation cannot be applied for these measurements. Instead, a neural network, trained on the results of Monte Carlo simulations, was used to estimate the absorption and scattering coefficients from the reflectance data. Tests on tissue-simulating phantoms with transport scattering coefficients between 0.5 and 2.0 mm-1 and absorption coefficients between 0.002 and 0.1 mm -1 showed the rms errors of this technique to be 2.6% for the transport scattering coefficient and 14% for the absorption coefficients. The optical properties of bovine muscle, adipose, and liver tissue, as well as chicken muscle (breast), were also measured ex vivo at 633 and 751 nm. For muscle tissue it was found that the Monte Carlo simulation did not agree with experimental measurements of reflectance at distances less than 2 mm from the incident beam. Carlo, neural network.

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

    NASA Astrophysics Data System (ADS)

    Wang, Jianbing; Zhang, Xianmei; Yu, Limin; Zhao, Xiang

    2014-02-01

    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 ?? of LH waves due to ? particles. Results show that, the ?? increases with the parallel refraction index n? while deceases with increasing the frequency of LH waves ?LH over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?? when ne?8×1019m-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.

  18. Realistic absorption coefficient of each individual film in a multilayer architecture

    NASA Astrophysics Data System (ADS)

    Cesaria, M.; Caricato, A. P.; Martino, M.

    2015-02-01

    A spectrophotometric strategy, termed multilayer-method (ML-method), is presented and discussed to realistically calculate the absorption coefficient of each individual layer embedded in multilayer architectures without reverse engineering, numerical refinements and assumptions about the layer homogeneity and thickness. The strategy extends in a non-straightforward way a consolidated route, already published by the authors and here termed basic-method, able to accurately characterize an absorbing film covering transparent substrates. The ML-method inherently accounts for non-measurable contribution of the interfaces (including multiple reflections), describes the specific film structure as determined by the multilayer architecture and used deposition approach and parameters, exploits simple mathematics, and has wide range of applicability (high-to-weak absorption regions, thick-to-ultrathin films). Reliability tests are performed on films and multilayers based on a well-known material (indium tin oxide) by deliberately changing the film structural quality through doping, thickness-tuning and underlying supporting-film. Results are found consistent with information obtained by standard (optical and structural) analysis, the basic-method and band gap values reported in the literature. The discussed example-applications demonstrate the ability of the ML-method to overcome the drawbacks commonly limiting an accurate description of multilayer architectures.

  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. Linear and nonlinear intersubband optical absorption coefficient and refractive index change in n-type ?-doped GaAs structure

    NASA Astrophysics Data System (ADS)

    Ozturk, Emine; Ozdemir, Yasin

    2013-05-01

    In the effective mass approximation, we have theoretically investigated the subband structure of single Si ?-doped GaAs by solving the Schrödinger and Poisson equations self-consistently. Both the linear and nonlinear intersubband optical absorption coefficients and the refractive index changes are calculated as dependent on the doping concentration and thickness. Our results show that the position and the magnitude of the linear and total absorption coefficients and refractive index changes depend on the doping concentration and thickness. The shape of potential profile and the subband energy differences are changed as dependent on the donor concentration and thickness. By considering the variation of the energy difference we can obtain a blue shift or a red shift in the intersubband optical transitions. The resonant peak of total absorption coefficient can be bleached at sufficiently high incident optical intensities. Such a dependence of the exciting optical intensity on the doping concentration and thickness can be very useful for several potential device applications.

  1. 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.

  2. Absorption Coefficient, Molecular Composition, and Photodegradation of Different Types of Brown Carbon Aerosols

    NASA Astrophysics Data System (ADS)

    Lee, H. J.; Aiona, P. K.; Nizkorodov, S.; Laskin, J.; Laskin, A.

    2014-12-01

    Atmospheric aerosols that absorb solar radiation have a direct effect on climate. Brown carbon (BrC) represents the type of carbonaceous aerosols characterized by large absorption coefficients in the near-UV range of the spectrum. BrC can be either directly emitted into the atmosphere from combustion sources, or be formed in the atmosphere through multi-phase reactions, such as aging of secondary organic aerosols (SOA) mediated by ammonium sulfate (AS). Under the conditions of exposure to solar radiation, both primary and secondary BrC can potentially change their molecular composition and optical properties as a result of photodegradation of chromophoric compounds. This presentation will discuss the molecular level composition, the absorption and fluorescence spectra, and the mechanism of photodegradation among several representative types of BrC. The primary BrC samples include aerosol produced by smoldering wood combustion. The secondary BrC samples include AS aged products of chamber-generated SOA, products of reaction between methylglyoxal and AS, and SOA produced by the hogh-NOx photooxdiation of aromatic compounds, such as naphthalene. This presentation will also include preliminary data on the absorption and fluorescence spectra of photo-degraded bioaerosols. In all cases, absorption spectra of extracted bulk samples are measured during irradiation by a known flux of UV or visible light. The molecular level composition of the fresh and photobleached samples are characterized by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). Photobleaching of BrC is found to occur over a range of atmospherically relevant time scales. In many cases, the molecular level composition of photobleached BrC exhibits only subtle changes suggesting that the optical and fluorescence properties of BrC are controlled by a few compounds present in low quantities. The observed fluorescence from non-biological BrC indicates potential issues in using fluorescence-based methods to detect bioaerosols. Overall, the results demonstrate a high degree of variability in optical properties and the highly dynamic nature of atmospheric BrC.

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

    E-print Network

    Firoozabadi, Abbas

    also accurately predicts infinite dilution diffusion coefficients for other binary water mixtures whereModeling 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

  4. Simulated X-Ray Absorption Spectroscopy on the Water Dimer

    SciTech Connect

    Wung, A

    2004-02-05

    The ability of an individual H{sub 2}O molecule to form multiple hydrogen bonds with neighboring molecules makes it an ideal substance for the study of hydrogen bonding. X-ray absorption spectroscopy (XAS) can be used to study what intermolecular structures the hydrogen-bonded water molecules form. XAS excites core electrons from the oxygen 1 s atomic orbital to an unoccupied orbital. The resulting absorption spectrum shows the energy levels of the unoccupied orbitals, which in turn is dependent on the intermolecular structure of the H{sub 2}O system. Previous studies using molecular dynamics computer simulations have concluded that the intermolecular structure of liquid water is a distorted tetrahedron. Yet x-ray absorption spectra show discrepancies between liquid water and ice Ih, which is already known to have a rigid tetrahedral structure. The research group, which is based in the University of Sweden in Stockholm and the Stanford Synchrotron Radiation Laboratory at the Stanford Linear Accelerator Center, has studied the possible presence of broken hydrogen bonds in the liquid water intermolecular structure to explain these deviations. Computer simulations are used to construct theoretical absorption spectra for models of liquid water including broken hydrogen bonds. Creating such models requires controlling variables. The simplest method of isolating individual variables, such as hydrogen bond length and angles, is to study the water dimer. Here, the water dimer is used to study how the absorption spectra change with the way the water molecules are positioned and oriented relative to each other.

  5. 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.

  6. 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...

  7. Absorption Coefficients of SF{6}, SF{4}, SOF{2} and SO{2}F{2} in the Vacuum Ultraviolet

    NASA Astrophysics Data System (ADS)

    Pradayrol, C.; Casanovas, A. M.; Deharo, I.; Guelfucci, J. P.; Casanovas, J.

    1996-05-01

    Absorption coefficients k0(m^{-1} 100 kPa^{-1}) of SF{6} and of its main gaseous by-products SF{4}, SOF{2} and SO{2}F{2} were measured in the VUV region. The experiments were carried out at a temperature of 298 K and a spectral resolution of 0.1 nm over the wavelength range 115 - 180 nm for SF{6}, 115 - 220 nm for SF{4}, 120 - 195 nm for SOF{2} and 120 - 210 nm for SO{2}F{2}. The highest absorption coefficient values were obtained for SF{4} and the lowest for SF{6}. Les coefficients d'absorption k0(m^{-1} 100 kPa^{-1}) du SF{6} et de ses principaux produits de décomposition gazeux, SF{4}, SOF{2} et SO{2}F{2} ont été mesurés dans le domaine de l'ultraviolet sous vide. Les expériences ont été réalisées à la température de 298 K avec une résolution de 0,1 nm dans la gamme 115 180 nm pour le SF{6}, 115 220 nm pour le SF{4}, 120 195 nm pour le SOF{2} et 120 210 nm pour le SO{2}F{2}. Les coefficients d'absorption les plus élevés ont été mesurés pour le SF{4} et les plus faibles pour le SF{6}.

  8. Scattering and absorption coefficients vs. Chemical composition of fine atmospheric aerosol particles under regional conditions in Hungary

    Microsoft Academic Search

    E Mészáros; A Molnár; J Ogren

    1998-01-01

    The light scattering and absorption coefficients of aerosol particles with a dry diameter below 1?m were recorded in the country air of Hungary. Concentrations of different inorganic and organic ions were measured in parallel to estimate the nature of particles causing light scattering. The sample air was heated gently to maintain a relative humidity of 30% and coarse particles were

  9. Two-photon absorption and Kerr coefficients of silicon for 8502200 nm Alan D. Bristow,a

    E-print Network

    Van Driel, Henry M.

    at a fundamental wavelength =1060 nm; a similar value was obtained by Boggess et al. at 300 K.16 Reitze et al.17Two-photon absorption and Kerr coefficients of silicon for 850­2200 nm Alan D. Bristow,a Nir at 300 K using 200 fs pulses with carrier wavelength of 850 2200 nm for which indirect gap transitions

  10. Effect of interdiffusion on band structure and intersubband absorption coefficient of GaAs\\/GaAlAs double quantum well

    Microsoft Academic Search

    V. L. Aziz Aghchegala; V. N. Mughnetsyan; A. A. Kirakosyan

    2011-01-01

    The influence of Ga and Al atoms interdiffusion on the band structure and absorption coefficient of coupled double quantum wells are investigated on the basis of a potential composed of four modified Wood–Saxon potentials. Wave functions of the real potential are expressed as a superposition of the stationary state wave functions of the “basal” potential. It is shown that interdiffusion

  11. Effect of interdiffusion on band structure and intersubband absorption coefficient of GaAs\\/GaAlAs double quantum well

    Microsoft Academic Search

    V. L. Aziz Aghchegala; V. N. Mughnetsyan; A. A. Kirakosyan

    2011-01-01

    The influence of Ga and Al atoms interdiffusion on the band structure and absorption coefficient of coupled double quantum wells are investigated on the basis of a potential composed of four modified Wood-Saxon potentials. Wave functions of the real potential are expressed as a superposition of the stationary state wave functions of the ``basal'' potential. It is shown that interdiffusion

  12. Inhibition of water absorption by ricinoleic acid

    Microsoft Academic Search

    Thomas R. Gadacz; Timothy S. Gaginella; Sidney F. Phillips

    1976-01-01

    In three dogs, each with a jejunal and an ileal Thiry-Vella loop, the isolated segments were perfused with isotonic electrolyte solutions (control) for 90 min. One loop was then perfused with 5 mM ricinoleic acid for an additional 90 min, while the other loop was perfused with the control solution. Loops perfused with ricinoleci acid all showed reduced fluid absorption.

  13. Accurate estimation of normal incidence absorption coefficients with confidence intervals using a scanning laser Doppler vibrometer

    NASA Astrophysics Data System (ADS)

    Vuye, Cedric; Vanlanduit, Steve; Guillaume, Patrick

    2009-06-01

    When using optical measurements of the sound fields inside a glass tube, near the material under test, to estimate the reflection and absorption coefficients, not only these acoustical parameters but also confidence intervals can be determined. The sound fields are visualized using a scanning laser Doppler vibrometer (SLDV). In this paper the influence of different test signals on the quality of the results, obtained with this technique, is examined. The amount of data gathered during one measurement scan makes a thorough statistical analysis possible leading to the knowledge of confidence intervals. The use of a multi-sine, constructed on the resonance frequencies of the test tube, shows to be a very good alternative for the traditional periodic chirp. This signal offers the ability to obtain data for multiple frequencies in one measurement, without the danger of a low signal-to-noise ratio. The variability analysis in this paper clearly shows the advantages of the proposed multi-sine compared to the periodic chirp. The measurement procedure and the statistical analysis are validated by measuring the reflection ratio at a closed end and comparing the results with the theoretical value. Results of the testing of two building materials (an acoustic ceiling tile and linoleum) are presented and compared to supplier data.

  14. Re-evaluation of pulsed photothermal radiometric profiling in samples with spectrally varied infrared absorption coefficient.

    PubMed

    Majaron, Boris; Milanic, Matija

    2007-02-21

    Spectral variation of the sample absorption coefficient in mid-infrared (muIR) demands caution in photothermal radiometric measurements, because a constant muIR is regularly assumed in inverse analysis of the acquired signals. Adverse effects of such approximation were recently demonstrated in numerical simulations of pulsed photothermal radiometric (PPTR) temperature profiling in soft biological tissues, utilizing a general-purpose optimization code in the reconstruction process. We present here an original reconstruction code, which combines a conjugate gradient minimization algorithm with non-negativity constraint to the sought temperature vector. For the same test examples as in the former report (hyper-Gaussian temperature profiles, InSb detector with 3-5 microm acquisition band, signal-to-noise ratio SNR=300) we obtain markedly improved reconstruction results, both when using a constant value mueff and when the spectral variation muIR(lambda) is accounted for in the analysis. By comparing the results, we find that the former approach introduces observable artefacts, especially in the superficial part of the profile (z<100 microm). However, the artefacts are much less severe than previously reported and are almost absent in the case of a deeper, single-lobed test profile. We demonstrate that the observed artefacts do not result from sub-optimal selection of mueff, and that they vary with specific realizations of white noise added to the simulated signals. The same holds also for a two-lobed test profile. PMID:17264372

  15. 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.

  16. 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.

  17. Space charge in polyimide film after water absorption

    Microsoft Academic Search

    Yutaka Kamei; M. Baba; S. Fujita

    2000-01-01

    A polyimide film exhibits high water absorption because of its imide bonds, which presents problems in practical applications. The PEA method was used to examine the effect of moisture content on space charge formation by measuring the space charge density in polyimide films that had been immersed in distilled water and changes in the space charge distribution over time. A

  18. Absorption coefficient of urban aerosol in Nanjing, west Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Zhuang, B. L.; Wang, T. J.; Liu, J.; Ma, Y.; Yin, C. Q.; Li, S.; Xie, M.; Han, Y.; Zhu, J. L.; Yang, X. Q.; Fu, C. B.

    2015-06-01

    Absorbing aerosols can significantly modulate shortwave solar radiation in the atmosphere, affecting regional and global climate. Aerosol absorption coefficient (AAC) is an indicator to assess the impact of absorbing aerosols on radiative forcing. In this study, the near-surface AAC and absorption angstrom exponent (AAE) in urban Nanjing, China, are characterized on the basis of measurements in 2012 and 2013 using the 7-channel Aethalometer (model AE-31, Magee Scientific, USA). The AAC is estimated with direct and indirect corrections, which show consistent temporal variations and magnitudes of AAC at 532 nm. The mean AAC at 532 nm is about 43.23 ± 28.13 M m-1 in urban Nanjing, which is much lower than that in Pearl River Delta and as the same as that in rural areas (Lin'an) in Yangtze River Delta. The AAC in urban Nanjing shows strong seasonality (diurnal variations), high in cold seasons (at rush hours) and low in summer (in afternoon). It also show synoptic and quasi-two-week cycles in response to weather systems. Its frequency distribution follows a typical lognormal pattern. The 532 nm-AAC ranging from 15 to 65 M m-1 dominates, accounting for more than 72% of the total data samples in the entire study period. Frequent high pollution episodes, such as those observed in June 2012 and in winter 2013, greatly enhanced AAC and altered its temporal variations and frequency distributions. These episodes are mostly due to local emissions and regional pollutions. Air masses from northern China to Nanjing can sometimes be highly polluted and lead to high AAC at the site. AAE at 660/470 nm from the Schmid correction (Schmid et al., 2006) is about 1.56, which might be more reasonable compared to that from the Weingartner correction (Weingartner et al., 2003). Low AAEs mainly appear in summer in response to the relative humidity (RH). AAC increases with increasing AAE at a fixed aerosol loading. The RH-AAC relationship is more complex. Overall, AAC peaks around RH values of 40% (1.3 < AAE < 1.6), 65% (AAE < 1.3 and AAE > 1.6), and 80% (1.3 < AAE < 1.6).

  19. 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

  20. A reduced-scale railway noise barrier's insertion loss and absorption coefficients: comparison of field measurements and predictions

    NASA Astrophysics Data System (ADS)

    Busch, T. A.; Nugent, R. E.

    2003-10-01

    In situ testing determined the insertion loss ( IL) and absorption coefficients of a candidate absorptive noise barrier (soundwall) to abate railway noise for residents of Anaheim, CA. A 4000 m barrier is proposed south of the tracks, but residential areas to the north have expressed concerns that barrier reflections will increase their noise exposure. To address these concerns, a 3.66 m high by 14.6 m long demonstration barrier was built in the parking lot of Edison Field, Anaheim, as part of a public open house, thereby allowing for acoustical measurements. Insertion loss ( IL) was measured in third-octave bands assuming 1/2-scale construction. The IL for three, scaled railway noise sub-sources (rail/wheel interface, locomotive, and train horn) was measured at six, scaled distances. The highest total, A-weighted IL, after corrections for finite-barrier and point-source speaker effects was 22 dB(A) for rail/wheel noise, 18 dB(A) for locomotive noise, and 20 dB(A) for train horn noise. These results can be compared favourably to IL predictions made using algorithms from the US Federal Rail Administration (FRA) noise assessment guidelines. For the actual barrier installation, shielded residential receivers located south of the project are expected to see their future noise exposures reduced from an unmitigated 78 CNEL to 65 CNEL. Absorption coefficients were measured using time delay spectrometry. At lower frequencies, measured absorption coefficients were notably less than the reverberation room results advertised in the manufacturer's literature, but generally conformed with impedance tube results. At higher frequencies the correspondence between measured absorption coefficients and reverberation room results was much improved. For the actual barrier installation, unshielded residential receivers to the north are expected to experience noise exposure increases of less than 1 dB(A). This factor of increase is consistent with a finding of no impact when assessed using FRA guidelines for allowable increases of noise exposure.

  1. Use of the light absorption coefficient to monitor elemental carbon and PM2.5--example of Santiago de Chile.

    PubMed

    Gramsch, Ernesto; Ormeño, Isabel; Palma, Guillermo; Cereceda-Balic, Francisco; Oyola, Pedro

    2004-07-01

    The optical absorption coefficient, particulate matter with an aerodynamic diameter <2.5 microm, and elemental carbon (EC) have been measured simultaneously during winter and spring of 2000 in the western part of Santiago, Chile (Pudahuel district). The optical measurements were carried out with a low-cost instrument recently developed at the University of Santiago. From the data, a site-specific mass absorption coefficient of 4.45+/-0.01 m2/g has been found for EC. In addition, a mass absorption coefficient of 1.02+/-0.03 m2/g has been obtained for PM2.5. These coefficients can be used during the colder months (May-August) to obtain EC concentration or PM2.5 from a measurement of the light absorption coefficient (sigmaa). The high correlation that has been found between these variables indicates that sigmaa is a good indicator of the degree of contamination of urbanized areas. The data also show an increase in PM2.5 and EC concentration during winter and an increase in the ratio of EC to PM2.5. When the EC/PM2.5 ratio is calculated during rush hour (7:00 a.m.-11:00 a.m.) and during part of the night (9:00 p.m.-2:00 a.m.), it is found that the increase is caused by higher concentration levels of EC at night. These results suggest that the rise in the EC concentration is caused by emissions from heating and air mass transport of pollution from other parts of the city, while traffic contribution remains approximately constant. PMID:15303292

  2. Endotoxin Temporarily Impairs Canine Colonic Absorption of Water and Sodium

    Microsoft Academic Search

    Joseph J. Cullen; Stephen T. Spates; Kimberly S. Ephgrave; Marilyn M. Hinkhouse

    1998-01-01

    Diarrhea is a common manifestation of sepsis. We hypothesized that endotoxin may impair colonic absorption of water and electrolytes, an effect which may be related to altered liquid transit in the colon. Five dogs underwent construction of 50-cm colonic Thiry–Vella fistulas (TVF). Following recovery, absorption studies were performed by perfusing the TVF with an isotonic solution at 2.9 ml\\/min containing

  3. Atmospheric Precorrected Differential Absorption technique to retrieve columnar water vapor

    SciTech Connect

    Schlaepfer, D.; Itten, K.I. [Univ. of Zuerich (Switzerland). Dept. of Geography] [Univ. of Zuerich (Switzerland). Dept. of Geography; Borel, C.C. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States); Keller, J. [Paul Scherrer Inst., Villigen (Switzerland)] [Paul Scherrer Inst., Villigen (Switzerland)

    1998-09-01

    Differential absorption techniques are suitable to retrieve the total column water vapor contents from imaging spectroscopy data. A technique called Atmospheric Precorrected Differential Absorption (APDA) is derived directly from simplified radiative transfer equations. It combines a partial atmospheric correction with a differential absorption technique. The atmospheric path radiance term is iteratively corrected during the retrieval of water vapor. This improves the results especially over low background albedos. The error of the method for various ground reflectance spectra is below 7% for most of the spectra. The channel combinations for two test cases are then defined, using a quantitative procedure, which is based on MODTRAN simulations and the image itself. An error analysis indicates that the influence of aerosols and channel calibration is minimal. The APDA technique is then applied to two AVIRIS images acquired in 1991 and 1995. The accuracy of the measured water vapor columns is within a range of {+-}5% compared to ground truth radiosonde data.

  4. The Forces Between Water Molecules and the Second Virial Coefficient for Water

    Microsoft Academic Search

    Henry Margenau; V. W. Myers

    1944-01-01

    In previous work on this subject, the second virial coefficient has been calculated with numerical success, but on the assumption of intermolecular forces which take inadequate cognizance of the known structure of the water molecule. In the present paper, all long range forces are computed in a semi-empirical way from dipole moment, quadrupole moment in accordance with the Bernal-Fowler analysis,

  5. 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

  6. 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%.

  7. Correction of water vapor absorption for aerosol remote sensing with ceilometers

    NASA Astrophysics Data System (ADS)

    Wiegner, M.; Gasteiger, J.

    2015-06-01

    In recent years attention was increasingly paid to backscatter profiles of ceilometers as a new source of aerosol information. Several case studies have shown that - although originally intended for cloud detection only - ceilometers can provide the planetary boundary layer height and even quantitative information such as the aerosol backscatter coefficient ?p, provided that the signals have been calibrated. It is expected that the retrieval of aerosol parameters will become widespread as the number of ceilometers is steadily increasing, and continuous and unattended operation is provided. In this context however one should be aware of the fact that the majority of ceilometers emit wavelengths that are influenced by atmospheric water vapor. As a consequence, profiles of aerosol parameters can only be retrieved if water vapor absorption is taken into account. In this paper we describe the influence of water vapor absorption on ceilometer signals at wavelengths in the range around ? = 910 nm. Spectrally high resolved absorption coefficients are calculated from HITRAN on the basis of realistic emission spectra of ceilometers. These results are used as reference to develop a methodology ("WAPL") for routine and near real time corrections of the water vapor influence. Comparison of WAPL with the reference demonstrates its very high accuracy. Extensive studies with simulations based on measurements reveal that the error when water vapor absorption is ignored in the ?p retrieval can be in the order of 20 % for mid-latitudes and more than 50 % for the tropics. It is concluded that the emission spectrum of the laser source should be provided by the manufacturer to increase the accuracy of WAPL, and that 910 nm is better suited than 905 nm. With WAPL systematic errors can be avoided, that would exceed the inherent random errors of the Klett solutions by far.

  8. Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

    NASA Technical Reports Server (NTRS)

    Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

    1995-01-01

    Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric balance measuring thrust and integrated pressure measurements along the length of the nozzle. Assessment of its value as a combustor performance evaluation tool will be conducted.

  9. Absorption coefficients of CFC-11 and CFC-12 needed for atmospheric remote sensing and global warming studies

    NASA Technical Reports Server (NTRS)

    Varanasi, Prasad

    1992-01-01

    Spectral absorption coefficients k(v) in the atmospheric window are reported for CFC-11 and CFC-12. Data obtained with a grating spectrometer are compared with NCAR cross sections and measurements of k(v) made with a tunable diode laser spectrometer at various temperature-pressure combinations representing tangent heights or layers in the atmosphere are presented. The results are suitable for atmospheric remote sensing and global warming studies.

  10. 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

  11. Effects of temperature-dependent molecular absorption coefficients on the thermal infrared remote sensing of the earth surface

    NASA Technical Reports Server (NTRS)

    Wan, Zhengming; Dozier, Jeff

    1992-01-01

    The effect of temperature-dependent molecular absorption coefficients on thermal infrared spectral signatures measured from satellite sensors is investigated by comparing results from the atmospheric transmission and radiance codes LOWTRAN and MODTRAN and the accurate multiple scattering radiative transfer model ATRAD for different atmospheric profiles. The sensors considered include the operational NOAA AVHRR and two research instruments planned for NASA's Earth Observing System (EOS): MODIS-N (Moderate Resolution Imaging Spectrometer-Nadir-Mode) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). The difference in band transmittance is as large as 6 percent for some thermal bands within atmospheric windows and more than 30 percent near the edges of these atmospheric windows. The effect of temperature-dependent molecular absorption coefficients on satellite measurements of sea-surface temperature can exceed 0.6 K. Quantitative comparison and factor analysis indicate that more accurate measurements of molecular absorption coefficients and better radiative transfer simulation methods are needed to achieve SST accuracy of 0.3 K, as required for global numerical models of climate, and to develop land-surface temperature algorithms at the 1-K accuracy level.

  12. 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.

  13. Absorption of Water Vapor into Aqueous Solutions of Lithium Bromide

    NASA Astrophysics Data System (ADS)

    Takahara, Tsutomu; Hayashida, Atsushi; Yabase, Hajime; Hihara, Eiji; Saito, Takamoto

    Heat and mass transfer processes are experimentally investigated for the case of water absorption into aqueous solutions of lithium bromide flowing over a flat plate. Variables considered are inlet solution flow rate,concentration of an additive,and inclination angle of the plate. The use of 2-ethyl-1-hexanol as an additive results in about a four to five fold improvement in absorption rate. The occurrence of surface distrbances dose not has a direct connection with the solubility limit of the additive. The cause of the surface disturbances in the presence of additives is investigated through experiments for pool absorption By regulating the flow of water vapor,the form of the Marangoni convection can be controlled. A qualitative discussion of addictives in the role of inducing surface disturbances is presented.

  14. Pool Boiling Heat Transfer Coefficients for Binary Mixtures of Acetone, Isopropanol, and Water

    Microsoft Academic Search

    U. Wenzel; F. Balzer; M. Jamialahmadi; H. Müller-Steinhagen

    1995-01-01

    Pool boiling heat transfer coefficients, bubble departure diameters, and nucleation site densities have been measured for binary mixtures of acetone, isopropanol, and water. The measured heat transfer coefficients are compared to the predictions of a correlation developed by Schliinder [1]. Different approaches to determine the ideal heat transfer coefficient required for this correlation are eualuaied.

  15. Absorption of ammonia from atmospheric plumes by natural water surfaces

    Microsoft Academic Search

    Kenneth L. Calder

    1972-01-01

    A simple model is presented that incorporates the major features of atmospheric transport and diffusion of a NH3 plume together with aqueous absorption as the plume traverses a water surface. The model is based on the well-known concept of the deposition velocity, although empirical data concerning the latter is quite meager. A specific application is considered to the gas release

  16. Estimation of diffusion coefficients for electrolytes in hot water. Final report. [PWR

    Microsoft Academic Search

    W. T. Jr

    1981-01-01

    Diffusion coefficients are calculated for electrolytes dissolved in water at temperatures 25 to 300°C and saturation pressures. Plots and tables are given of estimated diffusion coefficients for NaCl at concentrations from infinite dilution to 4 molal, limiting diffusion coefficients for divalent metal chlorides and for sodium phosphates of several compositions, and tracer diffusion coefficients for hydrochloric acid in sodium chloride

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

    Microsoft Academic Search

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

    2006-01-01

    Experimental determinations of mass and thermal accommodation coefficients alpham and alphat for condensation of water vapor in air have been conducted covering a temperature range from about 250 to 290 K. For the first time, both coefficients have been determined directly and simultaneously. To this end, growth of water droplets in air has been observed at different total gas pressures

  18. Sediment-Water Partition Coefficients of Hydrophobic Persistent Organic Pollutants (POPs)

    E-print Network

    Paris-Sud XI, Université de

    total organic carbon, black carbon and oil phases model) could model PCB data suc- cessfully whereas on the fraction of organic carbon (foc) and organic carbon­water partition coefficients (Koc) to correctly predict Sediment-Water Partition Coefficients of Hydrophobic Persistent Organic Pollutants (POPs

  19. Energy absorption probes control oily-water discharges

    SciTech Connect

    Agar, G.; Clewis, P. (Agar Corp., Houston, TX (United States)); Spencer, C. (Litwin Engineers and Constructors, Inc., Houston, TX (United States))

    1993-08-01

    Energy absorption instrumentation is rapidly emerging as the preferred method of interface control for separation processes. This high-frequency electromagnetic measurement technique accurately senses volume percentages (not level) in phase separations such as water and oil. Instead of searching for or assuming a clean interface, the instruments monitor percentages of water at points in the system, and can measure either water in oil or oil in water mixtures. This sensitivity gives the operator vision inside the system and consequently, more reliable control. Now unit operations can effectively monitor and reduce their oily-water releases. Reducing the work load on existing wastewater treatment systems lessens oil-grease levels in effluent water. Tighter hydrocarbon-release monitoring can bring discharges into compliance and diminish overall emission levels.

  20. Optoacoustic effect in dense layers of oriented carbon nanotubes: Its use for measuring the optical absorption coefficient and the film thickness

    Microsoft Academic Search

    I. S. Grudzinskaya; Z. Ya. Kosakovskaya; O. B. Ovchinnikov; I. A. Chaban

    2006-01-01

    The optoacoustic effect is used to measure the coefficient of light absorption at a wavelength of 0.53 ?m by a dense layer\\u000a of oriented carbon nanotubes on a quartz substrate. The value of the absorption coefficient is found to be equal to 3 106 m?1. This value is compared with the theoretical estimates and the estimate obtained from the reflection

  1. 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

  2. TEMPERATURE COEFFICIENT FOR MODELING DENITRIFICATION IN SURFACE WATER SEDIMENTS USING THE MASS TRANSFER COEFFICIENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With the cost of water quality research at the watershed level, modeling has become an important tool for researchers. When modeling nitrate transport within drainage networks, denitrification within the sediments needs to be accounted for. Birgand et al. developed an equation using a term called a ...

  3. 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.

  4. Reducing water absorption in compostable starch-based plastics

    Microsoft Academic Search

    M. Gáspár; Zs. Benk?; G. Dogossy; K. Réczey; T. Czigány

    2005-01-01

    To improve the mechanical and physical properties of corn starch-based bioplastics the addition of natural polymers was investigated. Thermoplastic starch (TPS) was made of 70g corn starch and 30g glycerol. To this mixture 10–10g of cellulose, hemicellulose and zein (protein) were added. Mechanical strength, water absorption and enzymatic degradation of composite materials were measured. Unfilled TPS and 10w\\/w% polycaprolactone filled

  5. Optical absorption of pure water in the blue and ultraviolet

    E-print Network

    Lu, Zheng

    2007-09-17

    OPTICAL ABSORPTION OF PURE WATER IN THE BLUE AND ULTRAVIOLET A Dissertation by ZHENG LU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 2006... Major Subject: Physics OPTICALABSORPTION OF PURE WATER IN THE BLUE AND ULTRAVIOLET A Dissertation by ZHENG LU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR...

  6. 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.

  7. Validation of phenol red versus gravimetric method for water reabsorption correction and study of gender differences in Doluisio's absorption technique.

    PubMed

    Tu?cu-Demiröz, Fatmanur; Gonzalez-Alvarez, Isabel; Gonzalez-Alvarez, Marta; Bermejo, Marival

    2014-10-01

    The aim of the present study was to develop a method for water flux reabsorption measurement in Doluisio's Perfusion Technique based on the use of phenol red as a non-absorbable marker and to validate it by comparison with gravimetric procedure. The compounds selected for the study were metoprolol, atenolol, cimetidine and cefadroxil in order to include low, intermediate and high permeability drugs absorbed by passive diffusion and by carrier mediated mechanism. The intestinal permeabilities (Peff) of the drugs were obtained in male and female Wistar rats and calculated using both methods of water flux correction. The absorption rate coefficients of all the assayed compounds did not show statistically significant differences between male and female rats consequently all the individual values were combined to compare between reabsorption methods. The absorption rate coefficients and permeability values did not show statistically significant differences between the two strategies of concentration correction. The apparent zero order water absorption coefficients were also similar in both correction procedures. In conclusion gravimetric and phenol red method for water reabsorption correction are accurate and interchangeable for permeability estimation in closed loop perfusion method. PMID:24887261

  8. Study of some factors affecting water absorption by faba beans during soaking

    Microsoft Academic Search

    Zakia M. Abdel Kader

    1995-01-01

    Water absorption by faba beans (Vicia faba) was determined by recording the weight increase in beans with respect to time. Temperature affected the rate of water absorption since the rates increased with increasing temperatures. The effects of soaking in the different concentrations of sodium bicarbonate have been studied. The rate of water absorption decreased with increasing concentrations of sodium bicarbonate

  9. 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

  10. Soil-water partition coefficients for organic compounds

    Microsoft Academic Search

    Bockting GJM; Plassche EJ van de; Struijs J; Canton JH

    2007-01-01

    In the frame of the project 'Setting environmental quality objectives',\\u000aorganic carbon normalized partition coefficients (KocS) describing the\\u000apartitioning of organic chemicals in soils and sediments were derived\\u000afor, among others, halogenated biphenyls and benzyltoluenes, chlorinated\\u000aanilines and nitrobenzenes, various pesticides, phthalate esters and\\u000aorganotin compounds. For that purpose a literature review with respect\\u000ato adsorption experiments with soils and

  11. Comparison of three measurement techniques for the normal absorption coefficient of sound absorbing materials in the free field.

    PubMed

    Hirosawa, Kunikazu; Takashima, Kazuhiro; Nakagawa, Hiroshi; Kon, Makoto; Yamamoto, Aki; Lauriks, Walter

    2009-12-01

    Three different techniques for evaluating the absorption coefficient of sound absorbing materials in free field conditions are discussed. One technique measures the acoustic impedance at one point nearby a specimen, the other two techniques evaluate the impedance from the transfer function of two sound pressures and two particle velocities at two points. These are called "PU-method," "PP-method," and "UU-method," respectively. An iterative algorithm to estimate the acoustic impedance of the locally reactive specimen in the spherical wave field is also applied. First, the effect of receiver positions, specimen areas, and source heights to the measured normal absorption coefficient is investigated by the boundary element method. According to these investigations, the PU-method is most stable against the effect of specimen area, and the UU-method is easily affected by that effect. Closer source to the specimen distance is advantageous for the signal to noise ratio of these measurement techniques, but correction for the effect of the spherical wave field has to be applied. As a finding, the iterative algorithm works for all of three techniques. Finally, the PU-method is applied experimentally with a pressure-velocity sensor and a loudspeaker in a hemi-anechoic room. As a result, the calculated results have been verified. PMID:20000915

  12. Field calibration of multi-scattering correction factor for aethalometer aerosol absorption coefficient during CAPMEX Campaign, 2008

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Kim, S. W.; Yoon, S. C.; Park, R.; Ogren, J. A.

    2014-12-01

    Filter-based instrument, such as aethalometer, is being widely used to measure equivalent black carbon(EBC) mass concentration and aerosol absorption coefficient(AAC). However, many other previous studies have poited that AAC and its aerosol absorption angstrom exponent(AAE) are strongly affected by the multi-scattering correction factor(C) when we retrieve AAC from aethalometer EBC mass concentration measurement(Weingartner et al., 2003; Arnott et al., 2005; Schmid et al., 2006; Coen et al., 2010). We determined the C value using the method given in Weingartner et al. (2003) by comparing 7-wavelngth aethalometer (AE-31, Magee sci.) to 3-wavelength Photo-Acoustic Soot Spectrometer (PASS-3, DMT) at Gosan climate observatory, Korea(GCO) during Cheju ABC plume-asian monsoon experiment(CAPMEX) campaign(August and September, 2008). In this study, C was estimated to be 4.04 ± 1.68 at 532 nm and AAC retrieved with this value was decreased as approximately 100% as than that retrieved with soot case value from Weingartner et al (2003). We compared the AAC determined from aethalomter measurements to that from collocated Continuous Light Absorption Photometer (CLAP) measurements from January 2012 to December 2013 at GCO and found good agreement in both AAC and AAE. This result suggests the determination of site-specific C is crucially needed when we calculate AAC from aethalometer measurements.

  13. Theoretical Calculation and Validation of the Water Vapor Continuum Absorption

    NASA Technical Reports Server (NTRS)

    Ma, Qiancheng; Tipping, Richard H.

    1998-01-01

    The primary objective of this investigation is the development of an improved parameterization of the water vapor continuum absorption through the refinement and validation of our existing theoretical formalism. The chief advantage of our approach is the self-consistent, first principles, basis of the formalism which allows us to predict the frequency, temperature and pressure dependence of the continuum absorption as well as provide insights into the physical mechanisms responsible for the continuum absorption. Moreover, our approach is such that the calculated continuum absorption can be easily incorporated into satellite retrieval algorithms and climate models. Accurate determination of the water vapor continuum is essential for the next generation of retrieval algorithms which propose to use the combined constraints of multi-spectral measurements such as those under development for EOS data analysis (e.g., retrieval algorithms based on MODIS and AIRS measurements); current Pathfinder activities which seek to use the combined constraints of infrared and microwave (e.g., HIRS and MSU) measurements to improve temperature and water profile retrievals, and field campaigns which seek to reconcile spectrally-resolved and broad-band measurements such as those obtained as part of FIRE. Current widely used continuum treatments have been shown to produce spectrally dependent errors, with the magnitude of the error dependent on temperature and abundance which produces errors with a seasonal and latitude dependence. Translated into flux, current water vapor continuum parameterizations produce flux errors of order 10 W/ml, which compared to the 4 W/m' magnitude of the greenhouse gas forcing and the 1-2 W/m' estimated aerosol forcing is certainly climatologically significant and unacceptably large. While it is possible to tune the empirical formalisms, the paucity of laboratory measurements, especially at temperatures of interest for atmospheric applications, preclude tuning the empirical continuum models over the full spectral range of interest for remote sensing and climate applications. Thus, we propose to further develop and refine our existing far-wing formalism to provide an improved treatment applicable from the near-infrared through the microwave. Based on the results of this investigation, we will provide to the remote sensing/climate modeling community a practical and accurate tabulation of the continuum absorption covering the near-infrared through the microwave region of the spectrum for the range of temperatures and pressures of interest for atmospheric applications.

  14. Theoretical Calculation and Validation of the Water Vapor Continuum Absorption

    NASA Technical Reports Server (NTRS)

    Ma, Qiancheng; Tipping, Richard H.

    1998-01-01

    The primary objective of this investigation is the development of an improved parameterization of the water vapor continuum absorption through the refinement and validation of our existing theoretical formalism. The chief advantage of our approach is the self-consistent, first principles, basis of the formalism which allows us to predict the frequency, temperature and pressure dependence of the continuum absorption as well as provide insights into the physical mechanisms responsible for the continuum absorption. Moreover, our approach is such that the calculated continuum absorption can be easily incorporated into satellite retrieval algorithms and climate models. Accurate determination of the water vapor continuum is essential for the next generation of retrieval algorithms which propose to use the combined constraints of multispectral measurements such as those under development for EOS data analysis (e.g., retrieval algorithms based on MODIS and AIRS measurements); current Pathfinder activities which seek to use the combined constraints of infrared and microwave (e.g., HIRS and MSU) measurements to improve temperature and water profile retrievals, and field campaigns which seek to reconcile spectrally-resolved and broad-band measurements such as those obtained as part of FIRE. Current widely used continuum treatments have been shown to produce spectrally dependent errors, with the magnitude of the error dependent on temperature and abundance which produces errors with a seasonal and latitude dependence. Translated into flux, current water vapor continuum parameterizations produce flux errors of order 10 W/sq m, which compared to the 4 W/sq m magnitude of the greenhouse gas forcing and the 1-2 W/sq m estimated aerosol forcing is certainly climatologically significant and unacceptably large. While it is possible to tune the empirical formalisms, the paucity of laboratory measurements, especially at temperatures of interest for atmospheric applications, preclude tuning, the empirical continuum models over the full spectral range of interest for remote sensing and climate applications. Thus, we propose to further develop and refine our existing, far-wing formalism to provide an improved treatment applicable from the near-infrared through the microwave. Based on the results of this investigation, we will provide to the remote sensing/climate modeling community a practical and accurate tabulation of the continuum absorption covering the near-infrared through the microwave region of the spectrum for the range of temperatures and pressures of interest for atmospheric applications.

  15. The measurement of the diffusion coefficient and the sorption isotherm of water in paint films

    Microsoft Academic Search

    A. J. J. van der Zanden; E. L. J. Goossens

    2003-01-01

    An experimental technique together with a numerical model is proposed with which the diffusion coefficient and the sorption isotherm of water in paint can be measured. Inside a closed vessel, paint films are on stainless-steel plates. Water is present as water vapour in the air and in the paint. After blowing dry or wet air through the vessel for some

  16. Water diffusion coefficients during copper electropolishing and IAN IVAR SUNI2*

    E-print Network

    Suni, Ian Ivar

    Water diffusion coefficients during copper electropolishing BING DU1 and IAN IVAR SUNI2* 1, including several with ethanol and other species added as diluents. Diluents allow a wider range of water in the mass transfer limited regime are shown to depend on both the number of water acceptor molecules

  17. Determination of mass and thermal accommodation coefficients from evolution of evaporating water droplet

    E-print Network

    Determination of mass and thermal accommodation coefficients from evolution of evaporating water trap placed in a small climatic chamber. The evolution of the droplet and the evolution dynamics this model to the experimental data, the mass and thermal accommodation coefficients were determined to be C

  18. Measurement of nonlinear absorption coefficients in GaAs, InP and Si by an optical pump THz probe technique

    NASA Astrophysics Data System (ADS)

    Tiedje, H. F.; Haugen, H. K.; Preston, J. S.

    2007-06-01

    An optical pump terahertz (THz) probe method for measuring carrier mobility and multiphoton absorption coefficients in semiconductors is demonstrated. A THz probe pulse is used to detect the transient photoconductivity generated by an optical pump pulse. The change in transmission coefficient at THz frequencies due to a pump pulse with photon energy greater than the band gap energy is used to determine the sum of electron and hole mobilities. The weak nonlinear absorption of a pump pulse with photon energy less than the band gap energy produces an approximately uniform free carrier distribution. The THz transmission coefficient vs. pump fluence, and the mobility, are used in a bulk photoconductivity model to determine the multiphoton absorption coefficients. For GaAs, InP and Si we find two photon absorption coefficients at 1305 nm of 42.5 ± 11, 70 ± 18 and 3.3 ± 0.9 cm/GW, respectively. For GaAs and InP we determine three photon absorption coefficients at 2144 nm of 0.19 ± 0.07 and 0.22 ± 0.08 cm 3/GW 2.

  19. A far wing line shape theory and its application to the foreign-broadened water continuum absorption. III

    NASA Technical Reports Server (NTRS)

    Ma, Q.; Tipping, R. H.

    1992-01-01

    The far wing line shape theory developed previously and applied to the calculation of the continuum absorption of pure water vapor is extended to foreign-broadened continua. Explicit results are presented for H2O-N2 and H2O-CO2 in the frequency range from 0 to 10,000/cm. For H2O-N2 the positive and negative resonant frequency average line shape functions and absorption coefficients are computed for a number of temperatures between 296 and 430 K for comparison with available laboratory data. In general the agreement is very good.

  20. Effect of the concentration of magnetic grains on the linear-optical-absorption coefficient of ferrofluid-doped lyotropic mesophases: deviation from the Beer-Lambert law.

    PubMed

    Cuppo, F L S; Gómez, S L; Figueiredo Neto, A M

    2004-04-01

    In this paper is reported a systematic experimental study of the linear-optical-absorption coefficient of ferrofluid-doped isotropic lyotropic mixtures as a function of the magnetic-grains concentration. The linear optical absorption of ferrolyomesophases increases in a nonlinear manner with the concentration of magnetic grains, deviating from the usual Beer-Lambert law. This behavior is associated to the presence of correlated micelles in the mixture which favors the formation of small-scale aggregates of magnetic grains (dimers), which have a higher absorption coefficient with respect to that of isolated grains. We propose that the indirect heating of the micelles via the ferrofluid grains (hyperthermia) could account for this nonlinear increase of the linear-optical-absorption coefficient as a function of the grains concentration. PMID:15170531

  1. Effect of the concentration of magnetic grains on the linear-optical-absorption coefficient of ferrofluid-doped lyotropic mesophases: Deviation from the Beer-Lambert law

    NASA Astrophysics Data System (ADS)

    Cuppo, F. L. S.; Gómez, S. L.; Figueiredo Neto, A. M.

    2004-04-01

    In this paper is reported a systematic experimental study of the linear-optical-absorption coefficient of ferrofluid-doped isotropic lyotropic mixtures as a function of the magnetic-grains concentration. The linear optical absorption of ferrolyomesophases increases in a nonlinear manner with the concentration of magnetic grains, deviating from the usual Beer-Lambert law. This behavior is associated to the presence of correlated micelles in the mixture which favors the formation of small-scale aggregates of magnetic grains (dimers), which have a higher absorption coefficient with respect to that of isolated grains. We propose that the indirect heating of the micelles via the ferrofluid grains (hyperthermia) could account for this nonlinear increase of the linear-optical-absorption coefficient as a function of the grains concentration.

  2. Trophic Magnification of PCBs and Its Relationship to the Octanol-Water Partition Coefficient

    EPA Science Inventory

    We investigated polychlorinated biphenyl (PCB) bioaccumulation relative to octanol-water partition coefficient (KOW) and organism trophic position (TP) at the Lake Hartwell Superfund (South Carolina, USA). We measured PCBs (127 congeners) and stable isotopes (d15...

  3. SUBSTITUENT CONTRIBUTION TO THE PARTITION COEFFICIENTS OF SUBSTITUTED BENZENES IN SOLVENT-WATER MIXTURES

    EPA Science Inventory

    In the course of correlation analysis for biological activities, octanol-water partition coefficients (P) have been used widely to express the lipophilic interactions of organic compounds with biological substrates. Since discrepancies are found between some pi values from differ...

  4. OVERALL MASS TRANSFER COEFFICIENT FOR POLLUTANT EMISSIONS FROM SMALL WATER POOLS UNDER SIMULATED INDOOR ENVIRONMENTAL CONDITIONS

    EPA Science Inventory

    Small chamber tests were conducted to experimentally determine the overall mass transfer coefficient for pollutant emissions from still water under simulated indoor-residential or occupational-environmental conditions. Fourteen tests were conducted in small environmental chambers...

  5. First CRDS-measurements of water vapour continuum in the 940 nm absorption band

    NASA Astrophysics Data System (ADS)

    Reichert, L.; Andrés Hernández, M. D.; Burrows, J. P.; Tikhomirov, A. B.; Firsov, K. M.; Ptashnik, I. V.

    2007-06-01

    Measurements of near-infrared water vapour continuum using continuous wave cavity ring down spectroscopy (cw-CRDS) have been performed at around 10611.6 and 10685.2cm. The continuum absorption coefficients for N2-broadening have been determined to be CF296K=(1.0±0.2)×10cmmolatm and CF278K=(1.8±0.4)×10cmmolatm at 10611.6cm, and CF296K=(1.6±0.5)×10cmmolatm and CF278K=(2.1±0.4)×10cmmolatm at 10685.2cm, respectively. These results represent the first near-IR continuum laboratory data determined within the complex spectral environment in the 940 nm water vapour band and are in reasonable agreement with simulations using the semiempirical CKD formulation.

  6. Demonstration of the Applicability of Novel Photoacoustic Aerosol Monitor for Optical Absorption Coefficient Determination. Laboratory and Field Test.

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Schnaiter, M.; Linke, C.; Vragel, M.; Filep, Á.; F?di, L.; Motika, G.; Bozóki, Z.; Szabó, G.

    2009-04-01

    Despite of its importance, the possibilities to determine the direct radiative forcing by atmospheric aerosols is very limited due to lack of the reliable on-line instruments. Therefore there is an increasing concern for novel methods promising more accurate and reliable results in this field. The accuracy and reliability of the available on-line instruments like SP2 (Single Particle Soot Photometer), MAAP (Multi Angle Absorption Photometer), are limited by the weakness of the spectral resolution or the sampling artefact of filter matrix during the light attenuation measurement on the deposited filter. These methods neither suitable for direct determination of the light absorption by aerosols nor dispose the capability of the source apportionment. In this work we present a novel photoacoustic based instrument for direct light absorption measurements in the atmosphere and demonstrate the suitability of that both in laboratory and field circumstances. We have developed a novel Multi Wavelength PhotoAcoustic System (WaSul-MuWaPas) based on the diode laser pumped, high repetition rate, Q-switched Nd:YAG laser and its frequency converted harmonics for direct determination of light absorption by aerosols. This instrument has designed to make in situ measurements at four different wavelengths simultaneously from the NIR to the UV wavelength range (1064nm, 532nm, 355nm, 266nm). The Wasul-MuWaPas measures directly the optical absorption coefficient on airborne particles, not belong to the integrated plate type technique (filter-free operation), operating at wide wavelength range (source apportionment possibilities), due to the possibilities of the wavelength independent cell constant determination the measurement method is absolute. Because of these the Wasul-MuWaPas system may become one of the best candidate for absorption measurements of various atmospheric aerosols such as black carbon, mineral dust, and secondary organic and inorganic aerosols as well as for source apportionment studies. The present system was successfully tested both under the laboratory and field circumstances. The results of these studied, demonstrated here, is shown excellent agreements with reference methods and presents the main characteristic performances of the system verifying the potential of Wasul-MuWaPas to characterizing the spectral properties of atmospheric aerosols. These researches were funded by Hungarian Ministry of Economy and Transport NKFP_07_A4_AEROS_EU.

  7. Modeling the Water-Supercritical CO2 Partition Coefficients of Organic Solutes Using a Linear Solvation Energy Relationship

    E-print Network

    Lagalante, Anthony F.

    LETTERS Modeling the Water-Supercritical CO2 Partition Coefficients of Organic Solutes Using relationship (LSER) has been developed to predict the water-supercritical CO2 partition coefficients% in the prediction of the water-supercritical CO2 partition coefficients for the six solutes considered. Results

  8. 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...

  9. 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

    Because the absorption refrigeration system uses the Lithium bromide- water solution as refrigerant, it is profitable for the environment that human beings are living since the values of ODP and GWP of the refrigerant almost are zero. However...

  10. Variability in light absorption and scattering of phytoplankton in Patagonian waters: Role of community size structure and pigment composition

    NASA Astrophysics Data System (ADS)

    Ferreira, Amabile; Stramski, Dariusz; Garcia, Carlos A. E.; Garcia, Virginia M. T.; Ciotti, ÁUrea M.; Mendes, Carlos R. B.

    2013-02-01

    Intense phytoplankton blooms were observed along the Patagonian shelf-break with satellite ocean color data, but few in situ optical observations were made in that region. We examine the variability of phytoplankton absorption and particulate scattering coefficients during such blooms on the basis of field data. The chlorophyll-a concentration, [Chla], ranged from 0.1 to 22.3 mg m-3 in surface waters. The size fractionation of [Chla] showed that 80% of samples were dominated by nanophytoplankton (N-group) and 20% by microphytoplankton (M-group). Chlorophyll-specific phytoplankton absorption coefficients at 440 and 676 nm, a*ph(440) and a*ph(676), and particulate scattering coefficient at 660 nm, b*p(660), ranged from 0.018 to 0.173, 0.009 to 0.046, and 0.031 to 2.37 m2 (mg Chla)-1, respectively. Both a*ph(440) and a*ph(676) were statistically higher for the N-group than M-group and also considerably higher than expected from global trends as a function of [Chla]. This result suggests that size of phytoplankton cells in Patagonian waters tends to be smaller than in other regions at similar [Chla]. The phytoplankton cell size parameter, Sf, derived from phytoplankton absorption spectra, proved to be useful for interpreting the variability in the data around the general inverse dependence of a*ph(440), a*ph(676), and b*p(660) on [Chla]. Sf also showed a pattern along the increasing trend of a*ph(440) and a*ph(676) as a function of the ratios of some accessory pigments to [Chla]. Our results suggest that the variability in phytoplankton absorption and scattering coefficients in Patagonian waters is caused primarily by changes in the dominant phytoplankton cell size accompanied by covariation in the concentrations of accessory pigments.

  11. 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

  12. Propagation of ultrashort laser pulses in water: linear absorption and onset of nonlinear spectral transformation.

    PubMed

    Sokolov, Alexei V; Naveira, Lucas M; Poudel, Milan P; Strohaber, James; Trendafilova, Cynthia S; Buck, William C; Wang, Jieyu; Strycker, Benjamin D; Wang, Chao; Schuessler, Hans; Kolomenskii, Alexandre; Kattawar, George W

    2010-01-20

    We study propagation of short laser pulses through water and use a spectral hole filling technique to essentially perform a sensitive balanced comparison of absorption coefficients for pulses of different duration. This study is motivated by an alleged violation of the Bouguer-Lambert-Beer law at low light intensities, where the pulse propagation is expected to be linear, and by a possible observation of femtosecond optical precursors in water. We find that at low intensities, absorption of laser light is determined solely by its spectrum and does not directly depend on the pulse duration, in agreement with our earlier work and in contradiction to some work of others. However, as the laser fluence is increased, interaction of light with water becomes nonlinear, causing energy exchange among the pulse's spectral components and resulting in peak-intensity dependent (and therefore pulse-duration dependent) transmission. For 30 fs pulses at 800 nm center wavelength, we determine the onset of nonlinear propagation effects to occur at a peak value of about 0.12 mJ/cm(2) of input laser energy fluence. PMID:20090819

  13. Absorption coefficients of the methane-nitrogen binary ice system: Implications for Pluto

    NASA Astrophysics Data System (ADS)

    Protopapa, S.; Grundy, W. M.; Tegler, S. C.; Bergonio, J. M.

    2015-06-01

    The methane-nitrogen phase diagram of Prokhvatilov and Yantsevich (1983. Sov. J. Low Temp. Phys. 9, 94-98) 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 N2 ? :CH4 and methane saturated with nitrogen CH4 ? :N2 . 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 (N2 :CH4) and nitrogen diluted in methane (CH4 :N2) are presented at temperatures between 40 and 90 K, in the wavelength range 1.1-2.7 ?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 presented.

  14. 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.

  15. 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...

  16. The x-ray absorption spectra of water and ice

    NASA Astrophysics Data System (ADS)

    Kong, Lingzhu; Wu, Xifan; Car, Roberto

    2012-02-01

    We calculate the x-ray absorption spectra of liquid water at STP, hexagonal ice and amorphous low- and high-density ice at T=269K, using the static Coulomb-hole and screened exchange self energy approach ootnotetextW. Chen, X. Wu and R. Car, PRL 105, 017802 (2008) . We take the nuclear quantum effects into account by averaging over the Feynman path-integral replicas. We find that quantum disorder is particularly important in liquid water where it substantially improves the structure ootnotetextJ. Morrone and R. Car, PRL 101, 017801 (2008) Compared to Ref. 2, we use an improved screening model that includes the approximate local field correction ootnotetextM. Hybertsen and S. G. Louie, PRB 37, 2733 (1988). The resulting spectra are in significantly better agreement with experiments than in previous calculations.

  17. Crop Coefficients and Water Use for Cowpea in the San Joaquin Valley of California.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve irrigation planning and management, an experiment was set up using a modified soil water balance to determine the crop coefficients and water use for cowpea in an area with a semi-arid climate and sandy soil. A 0.8-ha field was irrigated daily with a very efficient subsurface drip irrigat...

  18. Ground water contaminant source and transport parameter identification by correlation coefficient optimization

    Microsoft Academic Search

    P. Sidauruk; A. H. D. Cheng; D. Ouazar

    1998-01-01

    The initial step in a ground water contamination remediation process is to identify the extent of the plume. One way to optimize well deployment is to solve an inverse contaminant transport problem. Inverse procedures bas4ed on correlation coefficient optimization are developed to locate ground water contaminant sources and to identify transport parameters. For cases involving two-dimensional instantaneous and continuous sources,

  19. Extending Coastal Zone Color Scanner estimates of the diffuse attenuation coefficient into Case II waters

    Microsoft Academic Search

    Richard W. Gould; Robert A. Arnone

    1994-01-01

    An iterative technique has been developed to improve coastal zone color scanner (CZCS) estimates of upwelled subsurface water radiances (Lu) in Case II waters. Regional relationships between the diffuse attenuation coefficient measured at 490 nm (K490) and Lu measured at 443, 520, and 550 nm were developed using data collected in the northern Gulf of Mexico in April 1993. These

  20. Numerical simulation of electronic structure, linear and third order nonlinear optical absorption coefficients in the polymeric nanoheterostructure using imaginary time propagation method

    NASA Astrophysics Data System (ADS)

    Shakur, H. R.; Talebian Darzi, M. A.; Khani, P. H.; Maddahi, A. H.

    2012-06-01

    In the effective mass approximation, the charge density, the potential profile, the wavefunctions, and the corresponding energy states for zinc sulfide spherical quantum dot have been self-consistently solved, which is embedded in the polymeric media (PVP) by the imaginary time propagation method. Moreover, for the first time, the oscillator strength, linear, third order nonlinear, and total optical absorption coefficients for the transition between intersubbands 1s-1p, 1p-1d, 1d-1f, 1f-1g, 1g-1h, and 1h-1i are investigated with respect to photon energy and the saturation strength has been calculated for every transition too. Calculated result shows that the oscillator strength and the magnitude of optical absorption coefficients are enhanced for transition between intersubbands with higher energies. Also, calculations show that the total absorption coefficient depends on the strength of incident optical intensity and relaxation time.

  1. Water absorption in a refractive index model for bacterial spores

    NASA Astrophysics Data System (ADS)

    Siegrist, K. M.; Thrush, E.; Airola, M.; Carr, A. K.; Limsui, D. M.; Boggs, N. T.; Thomas, M. E.; Carter, C. C.

    2009-05-01

    The complexity of biological agents can make it difficult to identify the important factors impacting scattering characteristics among variables such as size, shape, internal structure and biochemical composition, particle aggregation, and sample additives. This difficulty is exacerbated by the environmentally interactive nature of biological organisms. In particular, bacterial spores equilibrate with environmental humidity by absorption/desorption of water which can affect both the complex refractive index and the size/shape distributions of particles - two factors upon which scattering characteristics depend critically. Therefore accurate analysis of experimental data for determination of refractive index must take account of particle water content. First, spectral transmission measurements to determine visible refractive index done on suspensions of bacterial spores must account for water (or other solvent) uptake. Second, realistic calculations of aerosol scattering cross sections should consider effects of atmospheric humidity on particle water content, size and shape. In this work we demonstrate a method for determining refractive index of bacterial spores bacillus atropheus (BG), bacillus thuringiensis (BT) and bacillus anthracis Sterne (BAs) which accounts for these effects. Visible index is found from transmission measurements on aqueous and DMSO suspensions of particles, using an anomalous diffraction approximation. A simplified version of the anomalous diffraction theory is used to eliminate the need for knowledge of particle size. Results using this approach indicate the technique can be useful in determining the visible refractive index of particles when size and shape distributions are not well known but fall within the region of validity of anomalous dispersion theory.

  2. Temperature effects on diffusion coefficient for 6-gingerol and 6-shogaol in subcritical water extraction

    NASA Astrophysics Data System (ADS)

    Ilia Anisa, Nor; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio

    2014-04-01

    6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10-11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10-11 m2/s.

  3. Comparison of the light absorption coefficient and carbon measures for remote aerosols: An independent analysis of data from the IMPROVE network—I

    Microsoft Academic Search

    H. Dale Huffman

    1996-01-01

    Using the IMPROVE network aerosol data from rural or remote sites across the United States, the ratio of the optically measured light absorption coefficient (?a) to the elemental carbon measured by Thermal\\/Optical Reflectance (TOR) analysis consistently indicates an absorption efficiency that is twice the accepted value of 10m2g?1. Correlations between ?a and the TOR carbon strongly suggest that the discrepancy

  4. Coefficient indicates if rod pump can unload water from gas well

    SciTech Connect

    Hu Yongquan; Wu Zhijun [Southwest Petroleum Inst., Nanchong (China)

    1995-09-11

    A sucker rod pump can efficiently dewater gas wells if the separation coefficient is sufficiently high. To determine this separation coefficient, it is not sufficient to only know if the system meets the criteria of rod string stress, horsehead load, and crankshaft torque. This paper reviews water production and gas locking problems at the Sichuan gas field and identifies the methodologies used to optimize the pumping efficiency of the area wells.

  5. 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.

  6. Effect of water absorption on the mechanical properties of poly(3-hydroxybutyrate)/vegetable fiber composites

    NASA Astrophysics Data System (ADS)

    Marinho, Vithória A. D.; Carvalho, Laura H.; Canedo, Eduardo L.

    2015-05-01

    The present work studies the effect of water absorption on the performance of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermoplastic obtained from renewable resources through low-impact biotechnological process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree.Water resistance is an important characteristic of structural composites, that may exposed to rain and humid environments. Both water absorption capacity (water solubility in the material) and the rate of water absorption (controlled by the diffusivity of water in the material) are important parameters. However, water absorption per se may not be the most important characteristic, insofar as the performance and applications of the compounds. It is the effect of the water content on the ultimate properties that determine the suitability of the material for applications that involve prolonged exposure to water.PHB/babassu composites with 0-20% load were prepared in an internal mixer. Two different types of babassu fibers having two different article size ranges were compounded with PHB and test specimens molded by compression. The water absorption capacity and the kinetic constant of water absorption were measured in triplicate. Mechanical properties under tension were measured for dry and moist specimens with different amounts of absorbed water.Results indicate that the performance of the composites is comparable to that of the pure matrix. Water absorption capacity increases from 0.7% (pure PHB) to 4% (PHB/20% babassu), but the water diffusivity (4.10?8 cm2/s) was found to be virtually independent of the water absorption level. Water absorption results in moderate drop in elastic modulus (10-30% at saturation, according to fiber content) but has little effect on tensile strength and elongation at break. Fiber type and initial particle size do not have a significant effect on water absorption or mechanical properties.

  7. Temperature and pressure dependence of methane correlations and osmotic second virial coefficients in water.

    PubMed

    Ashbaugh, Henry S; Weiss, Katie; Williams, Steven M; Meng, Bin; Surampudi, Lalitanand N

    2015-05-21

    We report methane's osmotic virial coefficient over the temperatures 275 to 370 K and pressures from 1 bar up to 5000 bar evaluated using molecular simulations of a united-atom description of methane in TIP4P/2005 water. In the first half of this work, we describe an approach for calculating the water-mediated contribution to the methane-methane potential-of-mean force over all separations down to complete overlap. The enthalpic, entropic, heat capacity, volumetric, compressibility, and thermal expansivity contributions to the water-mediated interaction free energy are subsequently extracted from these simulations by fitting to a thermodynamic expansion over all the simulated state points. In the second half of this work, methane's correlation functions are used to evaluate its osmotic second virial coefficient in the temperature-pressure plane. The virial coefficients evaluated from the McMillan-Mayer correlation function integral are shown to be in excellent agreement with those determined from the concentration dependence of methane's excess chemical potential, providing an independent thermodynamic consistency check on the accuracy of the procedures used here. At atmospheric pressure the osmotic virial coefficient decreases with increasing temperature, indicative of increasing hydrophobic interactions. At low temperature, the virial coefficient decreases with increasing pressure while at high temperature the virial coefficient increases with increasing pressure, reflecting the underlying hyperbolic dependence of the virial coefficient on temperature and pressure. The transition between a decreasing to increasing pressure response of the osmotic virial coefficient is shown to follow the response of the methane-methane contact peak to changes in pressure as a function of temperature, though a universal correlation is not observed. PMID:25932722

  8. An Assessment of Microwave Absorption Models and Retrievals of Cloud Liquid Water Using Clear-Sky Data

    SciTech Connect

    Marchand, Roger T.; Ackerman, Thomas P.; Westwater, Ed R.; Clough, Shepard A.; Cady-Pereira, Karen; Liljegren, James C.

    2003-12-19

    Passive microwave radiometers have a long history in the remote sensing of atmospheric liquid and water vapor. Retrievals of these quantities are sensitive to variations in pressure and temperature of the liquid and water vapor. Rather than use a statistical or climatological approach to account for the natural variability in atmospheric pressure and temperature, additional information on the atmospheric profile at the time of the radiometer measurements can be directly incorporated into the retrieval process. Such an approach has been referred to in the literature as a “physical-iterative” solution. This paper presents an assessment of the accuracy of the column liquid water path that can be expected using such an iterative technique as a result of uncertainties in the microwave emissions from oxygen and water vapor. It is shown that the retrieval accuracy is influenced by the accuracy of the instrument measurements and the quality of the atmospheric profiles of temperature and pressure, as one would expect. But also critical is the uncertainty in the absorption coefficients used in the underlying microwave radiative transfer model. The uncertainty in the absorption coefficients is particularly problematic in that it may well bias the liquid water retrieval. The differences between 3 absorption models examined in this paper are equivalent to a bias of 15 to 30 g/m2, depending on the total column water vapor. An examination of typical liquid water paths from the Southern Great Plains region of the United States shows that errors of this magnitude have significant implications for shortwave radiation and retrievals of cloud effective particle size.

  9. Influence of the light propagation models on a linearized photoacoustic image reconstruction of the light absorption coefficient

    NASA Astrophysics Data System (ADS)

    Okawa, Shinpei; Hirasawa, Takeshi; Kushibiki, Toshihiro; Ishihara, Miya

    2015-03-01

    Quantification of the optical properties of the tissues and blood by noninvasive photoacoustic (PA) imaging may provide useful information for screening and early diagnosis of diseases. Linearized 2D image reconstruction algorithm based on PA wave equation and the photon diffusion equation (PDE) can reconstruct the image with computational cost smaller than a method based on 3D radiative transfer equation. However, the reconstructed image is affected by the differences between the actual and assumed light propagations. A quantitative capability of a linearized 2D image reconstruction was investigated and discussed by the numerical simulations and the phantom experiment in this study. The numerical simulations with the 3D Monte Carlo (MC) simulation and the 2D finite element calculation of the PDE were carried out. The phantom experiment was also conducted. In the phantom experiment, the PA pressures were acquired by a probe which had an optical fiber for illumination and the ring shaped P(VDF-TrFE) ultrasound transducer. The measured object was made of Intralipid and Indocyanine green. In the numerical simulations, it was shown that the linearized image reconstruction method recovered the absorption coefficients with alleviating the dependency of the PA amplitude on the depth of the photon absorber. The linearized image reconstruction method worked effectively under the light propagation calculated by 3D MC simulation, although some errors occurred. The phantom experiments validated the result of the numerical simulations.

  10. Accurate determination of optical nonlinear absorption coefficients by the combination of reflection and transmission open-aperture z-scan measurements

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Wei, Jingsong

    2013-06-01

    In most z-scan measurements, the Fresnel reflection loss is generally negligible, which is reasonable for transparent samples or materials with small nonlinear coefficients. However, for semi-transparent samples with low transmission or samples with large nonlinear coefficients, the Fresnel reflection loss attributed to the nonlinear effect is large and must be considered in z-scan measurement and data fitting. In this study, we proposed a method and established the corresponding theoretical model and experimental configuration of combining the reflection open-aperture z-scan and the transmission open-aperture z-scan measurements to determine accurately the nonlinear absorption coefficients by considering the Fresnel reflection loss. The Sb2Te3 film was used as an example. The nonlinear absorption coefficient was experimentally measured and theoretically fitted by our model. The theoretical fitting curves are highly consistent with the experimental data, indicating that the theoretical model and the configuration of the experimental setup can reasonably and feasibly obtain an accurate nonlinear absorption coefficient in actual applications.

  11. Optical absorption of pure water in the blue and ultraviolet 

    E-print Network

    Lu, Zheng

    2007-09-17

    experimental investigation and analysis, we found that the absorption of Spectralon�® (the highly diffusive and reflective material used to build the ICAM) has a higher impact on measurements of absorption in the UV range than...

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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).

  18. Simple method to calculate octanol–water partition coefficient of organic compounds

    Microsoft Academic Search

    Elmira Arab Tehrany; Frantz Fournier; Stéphane Desobry

    2004-01-01

    Risk of molecular migration in food\\/packaging system is important consideration from safety, hygienic and economic points of view. Octanol\\/water system is a good reference for explanation of hydrophobic\\/hydrophilic character of food\\/packaging system.In this paper, quantitative structure-property relationships (QSPR) for estimating logP values (octanol\\/water partition coefficient) were developed based on molecular descriptors using a set of 42 organic compounds (aromas compounds

  19. Pore-size dependent THz absorption of nano-confined water.

    PubMed

    Sun, Chi-Kuang; You, Borwen; Huang, Yu-Ru; Liu, Kao-Hsiang; Sato, Shusaku; Irisawa, Akiyoshi; Imamura, Motoki; Mou, Chung-Yuan

    2015-06-15

    We performed a THz absorption spectroscopy study on liquid water confined in mesoporous silica materials, MCM-41-S-18 and MCM-41-S-21, of two different pore sizes at room temperatures. We found that stronger confinement with a smaller pore size causes reduced THz absorption, indicating reduced water mobility due to confinement. Combined with recent theoretical studies showing that the microscopic structure of water inside the nanopores can be separated into a core water region and an interfacial water region, our spectroscopy analysis further reveals a bulk-water-like THz absorption behavior in the core water region and a solid-like THz absorption behavior in the interfacial water region. PMID:26076248

  20. Mass accommodation coefficient of water: A combined computational fluid dynamics and experimental data analysis

    Microsoft Academic Search

    J. Voigtländer; F. Stratmann; D. Niedermeier; H. Wex; A. Kiselev

    2007-01-01

    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

  1. Spreading Waves of a Reduced Diffusion Coefficient of Water in Normal and Ischemic Rat Brain

    Microsoft Academic Search

    Yasuhiro Hasegawa; Lawrence L. Latour; James E. Formato; Christopher H. Sotak; Marc Fisher

    1995-01-01

    Summary: Using echo planar diffusion-weighted magnetic resonance imaging, we measured three-dimensional changes in the apparent diffusion coefficient (ADC) of water in eight contiguous coronal slices, encompassing the entire rat brain, before and after local cortical stimulation. We applied chemical (potassium chloride application; n = 6) and mechanical (needle stab; n = 4) stimulations to the right posterior parietal rat cortex.

  2. 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 ...

  3. 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...

  4. 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...

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

    E-print Network

    Kandlikar, Satish

    at higher temperature operation. Diffusion in porous media results in a reduction in the free stream binary used in fuel cell literature is the Bruggeman equation [4] which adjusts the binary diffusionDetermination of effective water vapor diffusion coefficient in pemfc gas diffusion layers Jacob M

  6. Estimation of mortality coefficients and survivorship curves for minke whales (Balaenoptera acutorostrata) in Korean waters

    Microsoft Academic Search

    Chang Ik Zhang; Kyung-Jun Song; Jong-Hun Na

    2010-01-01

    Population ecological characteristics of growth and mortality play an important role in understanding the population dynamics of marine mammals. The instantaneous coefficients of natural and bycatch mortality were estimated for minke whales (Balaenoptera acutorostrata) in Korean waters using a population assessment model composed of bycatch and abundance data. The survivorship curve of this population was fitted to the data, and

  7. 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.

  8. Surface arsenic speciation of a drinking-water treatment residual using X-ray absorption spectroscopy

    Microsoft Academic Search

    Konstantinos C. Makris; Dibyendu Sarkar; Jason G. Parsons; Rupali Datta; Jorge L. Gardea-Torresdey

    2007-01-01

    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

  9. Surface Arsenic Speciation of a Drinking-Water Treatment Residual Using X-Ray Absorption Spectroscopy

    Microsoft Academic Search

    K. C. Makris; D. Sarkar; J. G. Parsons; R. Datta; J. L. Gardea-Torresdey

    2009-01-01

    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

  10. Near-infrared diode laser absorption diagnostic for temperature and water vapor in a scramjet combustor

    Microsoft Academic Search

    Tarun Mathur

    2005-01-01

    Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34-1.47 μm spectral region (2v1and v1+ v3overtone bands). Ratio thermometry was performed using direct-absorption wavelength scans of isolated features

  11. 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.

  12. 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.

  13. 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).

  14. 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

  15. Spectral absorption properties of dissolved and particulate matter in Lake Erie

    Microsoft Academic Search

    Caren E. Binding; John H. Jerome; Robert P. Bukata; William G. Booty

    2008-01-01

    Spectral absorption properties of particulate and dissolved matter were determined for Lake Erie waters in order to investigate the natural variability of the absorption coefficients required as inputs to optical models for converting satellite observations of water colour into water quality information. Particulate absorption measured using the quantitative filter technique yielded absorption spectra containing a fraction that could not be

  16. STUDY OF NON-UNIFORMITY COEFFICIENT CONSIDERING MICROTOPOGRAPHY FOR SEISMIC DESIGN OF WATER PIPELINE

    NASA Astrophysics Data System (ADS)

    Shichiroumaru, Kazutaka; Miyajima, Masakatsu

    This study is focusing on a non-uniformity coefficient of ground in the earthquake-resistant of a water pipeline. A lot of earthquake damage occurs at high non-uniformity ground. Therefore it is necessary to consider non-uniformity at the earthquake-resistant of the underground pipeline. By using a microtopography classification, non-uniformity coefficient in the boundary in the microtopography is studied. As a result, earthquake damage rate of underground pipeline at the boundary of the microtopography tends to be high. Therefore, the non-uniformity at the boundary can be obtained from a kind of microtopography and the boundary condition.

  17. Ultrasonic measurements of the reflection coefficient at a water/polyurethane foam interface.

    PubMed

    Sagers, Jason D; Haberman, Michael R; Wilson, Preston S

    2013-09-01

    Measured ultrasonic reflection coefficients as a function of normal incidence angle are reported for several samples of polyurethane foam submerged in a water bath. Three reflection coefficient models are employed as needed in this analysis to approximate the measured data: (1) an infinite plane wave impinging on an elastic halfspace, (2) an infinite plane wave impinging on a single fluid layer overlying a fluid halfspace, and (3) a finite acoustic beam impinging on an elastic halfspace. The compressional wave speed in each sample is calculated by minimizing the sum of squared error (SSE) between the measured and modeled data. PMID:23968059

  18. 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.

  19. Geoacoustic inversion of range-dependent shallow-water data using a complex plane-wave reflection coefficient approach

    Microsoft Academic Search

    Steven A. Stotts; David P. Knobles; Robert A. Koch

    2003-01-01

    The inversion of range-dependent broadband data in shallow water is presented using a previously developed approach with rays and complex bottom plane-wave reflection coefficients [Stotts, J. Acoust. Soc. Am. 109, 2334 (2001)], allowing separation of seabed physics from water column contributions. Using geometrical optics, waterborne eigenray characteristics are calculated once and stored. Model fields are calculated by including reflection coefficient

  20. 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

  1. Buckminsterfullerene's (C60) octanol-water partition coefficient (Kow) and aqueous solubility.

    PubMed

    Jafvert, Chad T; Kulkarni, Pradnya P

    2008-08-15

    To assess the risk and fate of fullerene C60 in the environment, its water solubility and partition coefficients in various systems are useful. In this study, the log Kow of C60 was measured to be 6.67, and the toluene-water partition coefficient was measured at log Ktw = 8.44. From these values and the respective solubilities of C60 in water-saturated octanol and water-saturated toluene, C60's aqueous solubility was calculated at 7.96 ng/L(1.11 x 10(-11) M) for the organic solvent-saturated aqueous phase. Additionally, the solubility of C60 was measured in mixtures of ethanol-water and tetrahydrofuran-water and modeled with Wohl's equation to confirm the accuracy of the calculated solubility value. Results of a generator column experiment strongly support the hypothesis that clusters form at aqueous concentrations below or near this calculated solubility. The Kow value is compared to those of other hydrophobic organic compounds, and bioconcentration factors for C60 were estimated on the basis of Kow. PMID:18767649

  2. 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

  3. 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.

  4. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV

    NASA Astrophysics Data System (ADS)

    Buhr, H.; Büermann, L.; Gerlach, M.; Krumrey, M.; Rabus, H.

    2012-12-01

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given.

  5. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV.

    PubMed

    Buhr, H; Büermann, L; Gerlach, M; Krumrey, M; Rabus, H

    2012-12-21

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given. PMID:23192280

  6. 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

  7. 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.

  8. Infrared spectra and molar absorption coefficients of the 20 alpha amino acids in aqueous solutions in the spectral range from 1800 to 500 cm -1

    NASA Astrophysics Data System (ADS)

    Wolpert, Martina; Hellwig, Petra

    2006-07-01

    In this work, we present the absorption spectra and molar coefficients of all 20 amino acids in aqueous solutions down to 500 cm -1. The spectral region between 1200 and 500 cm -1 was yet disregarded for protein infrared spectroscopy, mainly due to the strong H 2O absorption. Absorption spectra were obtained mainly for physiological relevant pH region. Intense bands for aromatic amino acids, histidine and such with OH group could clearly be identified throughout the given spectral region. For sulfur-containing amino acids cysteine and methionine some strong bands besides the weak carbon-sulfur stretching vibration was shown. Effects of aqueous solution environment, pH, protonation states were discussed, together with previously reported data from theoretical approaches. With this complete set of spectral information application to proteins in the whole mid infrared region could be described precise and the potential of the lower spectral region to study typical cofactor ligands like histidine, shown.

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

    NASA Astrophysics Data System (ADS)

    Baines, K. H.; West, R. A.; Giver, L. P.; Moreno, F.

    1993-03-01

    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.

  10. Strong enhancement in light absorption by black carbon due to aerosol water uptake

    NASA Astrophysics Data System (ADS)

    Fierce, Laura; Mena, Francisco; Riemer, Nicole; Bond, Tami C.; Bauer, Susanne E.

    2015-04-01

    Black carbon exerts a strong, yet highly uncertain, warming effect on the climate. One source of uncertainty in predicting black carbon's radiative effects is the absorption per black carbon mass. Although models suggest that light absorption is strongly enhanced if black carbon is coated with non-absorbing aerosol material, recent ambient observations find only weak absorption enhancement from aerosol coatings. In this study, we use a particle-resolved aerosol model to evaluate how oversimplified representations of particle composition impact modeled light absorption by black carbon. We show that oversimplifying the representation of particle composition leads to overestimation of modeled absorption enhancement. In order to improve global model representations of BC absorption, we performed a nonparametric regression on particle-reolved model data from a series of simulations. Through this nonparametric analysis we derived a relationship for absorption enhancement as a function of variables that global models already track, the population-averaged composition and the environmental relative humidity. Finally, we show how this nonparametric relationship can be exploited for use in global models to improve predictions of absorption by black carbon. In order to quantify the global-scale impact of water uptake on light absorption by black carbon, we applied the relationship for absorption enhancement to output of the climate model GISS-MATRIX. We find weak absorption enhancement in locations with low relative humidity, but light absorption is strongly enhanced in humid regions. This enhancement in light absorption by particles taking up water strongly impacts black carbon's radiative effects at the global scale, enhancing light absorption by black carbon by 20% relative to dry conditions.

  11. Absorption of short-chain fatty acids, sodium and water from the forestomach of camels.

    PubMed

    von Engelhardt, W; Dycker, Ch; Lechner-Doll, M

    2007-08-01

    In camelids the ventral parts of compartments 1 and 2 (C1/C2) and the total surface of compartment 3 of the forestomach are lined with tubular glands, whereas in ruminants the surface of the forestomach is composed entirely of stratified, squamous epithelium. Thus, differences in absorption rates between these foregut fermenters can be expected. In five camels C1/C2 was temporarily isolated, washed and filled with buffer solutions. Absorption of short-chain fatty acids (SCFA) and net absorption of sodium and water were estimated relative to Cr-ethylenediaminetetraacetic acid as a fluid marker. SCFA were extensively absorbed in the forestomach; clearance rates of SCFA with different chain lengths were equal. After lowering the pH of solutions SCFA absorption rates increased, but much less than the increase of the non-ionized fraction. Absorption of propionate was lower when acetate had been added. Findings suggest that most of the SCFA in camels are transported in the ionized form, most likely via an anion exchange mechanism. Net water absorption is closely related to net sodium absorption. Apparently water absorption results from an iso-osmotic process. Differences between absorption mechanisms of SCFA from the forestomach of camelids and ruminants are discussed. PMID:17429653

  12. 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

  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. 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...

  15. A Three-Wavelength Optical Extinction Cell for Measuring Aerosol Light Extinction and Its Application to Determining Light Absorption Coefficient

    Microsoft Academic Search

    Aki Virkkula; Norman C. Ahlquist; Patrick J. Sheridan; William P. Arnott; John A. Ogren

    2005-01-01

    An optical extinction cell (OEC) was used to measure aerosol particle extinction coefficient ?EP at three wavelengths, 467, 530, and 660 nm. The details of the design and the results of its use in the Reno Aerosol Optics Study (RAOS) in June 2002 are presented. The OEC agreed well with the scattering coefficient ?SP measured using an integrating nephelometer for

  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 refrigeration method with alternative water-ammonia solution circulation system for microelectronics cooling

    Microsoft Academic Search

    Victor Chiriac; Florea Chiriac

    2010-01-01

    The study develops an analytical model of an optimized small scale absorption ammonia\\/water refrigeration system, designed to fit smaller scale power electronics, using a pump to circulate the binary ammonia-water solution cooling agent in the proposed miniaturized system. This continues the authors' previous study of a refrigeration absorption system, by replacing the thermo-siphon and gravitational based circulation of the compensatory

  18. The effect of amino acids and dipeptides on sodium and water absorption in man

    Microsoft Academic Search

    M. D. Hellier; C. Thirumalai; C. D. Holdsworth

    1973-01-01

    A perfusion technique has been used to quantitate the effect of the amino acids glycine and alanine and the dipeptides glycyl-glycine and glycyl-L-alanine on sodium and water absorption from the human jejunum. Although no net absorption of sodium and water was seen in the absence of non-electrolytes, a significant stimulation occurred in the presence of both free amino acids and

  19. Water absorption and desorption in shuttle ablator and insulation materials

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.; Smith, C. F.; Wooden, V. A.; Cothren, B. E.; Gregory, H.

    1982-01-01

    Shuttle systems ablator and insulation materials underwent water soak with subsequent water desorption in vacuum. Water accumulation in these materials after a soak for 24 hours ranged from +1.1% for orbiter tile to +161% for solid rocket booster MSA-1. After 1 minute in vacuum, water retention ranged from none in the orbiter tile to +70% for solid rocket booster cork.

  20. 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).

  1. 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.

  2. 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

  3. Retrieving the translational diffusion coefficient of water from experiments on single levitated aerosol droplets.

    PubMed

    Lienhard, Daniel M; Huisman, Andrew J; Bones, David L; Te, Yiea-Funk; Luo, Bei P; Krieger, Ulrich K; Reid, Jonathan P

    2014-08-21

    The time-dependent growth and shrinkage of aqueous aerosol particles trapped in an electrodynamic balance exposed to changes in relative humidity (RH) depend on the translational diffusion coefficient of water (DH2O). Resonances in the Mie scattering patterns of the illuminated micrometre-sized droplets are used to follow the compositional evolution through stepwise changes in RH. Under conditions where the diffusion of water molecules becomes sufficiently slow, e.g. in the highly viscous or even glassy regime, the concentration and temperature dependent values of DH2O can be determined iteratively by comparing the observed shifts in the Mie resonant wavelengths with predicted shifts from a diffusion model of a multi-layered sphere. It is shown that condensation and evaporation of water vapour from or to highly viscous or glassy droplets follow different kinetic regimes, a result that is consistent with previous studies of adsorption and desorption on glassy surfaces. PMID:24998384

  4. Prediction of gas/water mass transport coefficients by a surface renewal model

    SciTech Connect

    Asher, W.E.; Pankow, J.F. (Oregon Graduate Inst., Beaverton (United States))

    1991-07-01

    Aqueous-phase carbon dioxide concentration fluctuation time scales measured at carbon dioxide/water interfaces were used in a surface renewal model to calculate the aqueous-phase mass-transport coefficient k{sub L} for a range of turbulence conditions for cleaned and film-covered water surfaces. The calculated k{sub L} values were compared to measured k{sub L} values from a separate set of experiments over the same range of turbulence and interfacial conditions. This test of a surface renewal model with directly measured parameters has shown that k{sub L} may be accurately estimated by the model for clean interfaces and high turbulence intensities. The data also show that surface renewal models are not appropriate for calculating mass fluxes at film-covered water surfaces.

  5. Effect of Water Vapor Absorption on Measurements of Atmospheric Nitrate Radical by LP-DOAS

    NASA Astrophysics Data System (ADS)

    Li, Su-wen; Liu, Wen-qing; Xie, Pin-hua; Yang, Yi-jun; Chen, De-bao; Li, Zheng

    2008-10-01

    During the measurement of atmospheric nitrate radical by long-path differential optical absorption spec-troscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.

  6. Water absorption and interface reactivity of yttrium oxide gate dielectrics on silicon

    NASA Astrophysics Data System (ADS)

    Niu, D.; Ashcraft, R. W.; Parsons, G. N.

    2002-05-01

    High dielectric constant insulators deposited at low temperatures rapidly absorb water during exposure to the atmosphere, and the resulting OH leads to detrimental interface reactions. We report the effect of atmospheric exposure on ultrathin yttrium oxide, and details of silicon substrate reactions during postdeposition anneals. Infrared absorption analysis indicates significant absorption of water vapor during atmospheric exposure, even for very short times (<15 min). X-ray photoelectron spectroscopy demonstrates that after OH absorption, a thermally activated interface reaction proceeds with an activation energy of 0.33 eV, consistent with substrate reaction with OH present in the film. The OH absorption rate is reduced for annealed films or when capping layers are deposited in situ. Similar oxidation processes are expected to occur in other high-k materials of interest, where the rate of OH absorption will depend on the deposition process and material thermal history.

  7. 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.

  8. Improving Spectral Crop Coefficient Approach with Raw Image Digital Count Data to Estimate Crop Water Use

    NASA Astrophysics Data System (ADS)

    Shafian, S.; Maas, S. J.; Rajan, N.

    2014-12-01

    Water resources and agricultural applications require knowledge of crop water use (CWU) over a range of spatial and temporal scales. Due to the spatial density of meteorological stations, the resolution of CWU estimates based on these data is fairly coarse and not particularly suitable or reliable for water resources planning, irrigation scheduling and decision making. Various methods have been developed for quantifying CWU of agricultural crops. In this study, an improved version of the spectral crop coefficient which includes the effects of stomatal closure is applied. Raw digital count (DC) data in the red, near-infrared, and thermal infrared (TIR) spectral bands of Landsat-7 and Landsat-8 imaging sensors are used to construct the TIR-ground cover (GC) pixel data distribution and estimate the effects of stomatal closure. CWU is then estimated by combining results of the spectral crop coefficient approach and the stomatal closer effect. To test this approach, evapotranspiration was measured in 5 agricultural fields in the semi-arid Texas High Plains during the 2013 and 2014 growing seasons and compared to corresponding estimated values of CWU determined using this approach. The results showed that the estimated CWU from this approach was strongly correlated (R2 = 0.79) with observed evapotranspiration. In addition, the results showed that considering the stomatal closer effect in the proposed approach can improve the accuracy of the spectral crop coefficient method. These results suggest that the proposed approach is suitable for operational estimation of evapotranspiration and irrigation scheduling where irrigation is used to replace the daily CWU of a crop.

  9. Water vapor absorption spectrum measurements and its application in concentration measurement

    NASA Astrophysics Data System (ADS)

    Chang, Jun; Chen, Kun; Zhou, Guoqing; Lv, Guangping; Zhu, Cunguang; Wang, Zhongliang; Song, Fujun; Song, Haiyong; Tian, Junqiang; Hou, Wenjia; Huang, Jiaqing

    2012-02-01

    Wavelength tunable distributed feedback laser diode (DFB-LD) were utilized to measure line 1368.597nm and line 1367.862 nm absorption character of water vapor, based on it, water vapor concentration can be measured by peak absorption rate according to Beer-Lambert law. Besides, we observe that the overlap between the line 1368.597nm and line 1367.862 nm appears and become serious with the increase of gas pressure, this agrees well with the theoretical prediction, and the overlap cause difficulty to determine the absorption peak value, a scheme is presented to cope with the difficulty, it takes advantage of the peak absorption difference between 1368.597nm and 1367.862 nm, and the difference value is used to calculate the water-vapor concentration.

  10. Measurement of activity coefficients at infinite dilution for acetonitrile, water, limonene, limonene epoxide and their binary pairs

    Microsoft Academic Search

    Rolando Barrera Zapata; Aída Luz Villa; Consuelo Montes de Correa

    2009-01-01

    Activity coefficients at infinite dilution were determined for binary pairs of acetonitrile, water, limonene and limonene epoxide at room temperature using the dilutor technique (inert gas stripping) in a home-made dilutor apparatus. The activity coefficients were predicted with the Aspen Plus software using the Dortmund-modified UNIFAC contribution method. Values predicted by software simulations are in good agreement with experimental data.

  11. Absorption of Sunlight by Water Vapor in Cloudy Conditions: A Partial Explanation for the Cloud Absorption Anomaly

    NASA Technical Reports Server (NTRS)

    Crisp, D.

    1997-01-01

    The atmospheric radiative transfer algorithms used in most global general circulation models underestimate the globally-averaged solar energy absorbed by cloudy atmospheres by up to 25 W/sq m. The origin of this anomalous absorption is not yet known, but it has been attributed to a variety of sources including oversimplified or missing physical processes in these models, uncertainties in the input data, and even measurement errors. Here, a sophisticated atmospheric radiative transfer model was used to provide a more comprehensive description of the physical processes that contribute to the absorption of solar radiation by the Earth's atmosphere. We found that the amount of sunlight absorbed by a cloudy atmosphere is inversely proportional to the solar zenith angle and the cloud top height, and directly proportional to the cloud optical depth and the water vapor concentration within the clouds. Atmospheres with saturated, optically-thick, low clouds absorbed about 12 W/sq m more than clear atmospheres. This accounts for about 1/2 to 1/3 of the anomalous ab- sorption. Atmospheres with optically thick middle and high clouds usually absorb less than clear atmospheres. Because water vapor is concentrated within and below the cloud tops, this absorber is most effective at small solar zenith angles. An additional absorber that is distributed at or above the cloud tops is needed to produce the amplitude and zenith angle dependence of the observed anomalous absorption.

  12. Photonic crystal slot waveguide for high sensitivity on-chip near-infrared optical absorption spectroscopy of xylene in water

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Lai, Wei-Cheng; Wang, Xiaolong; Lin, Che-Yun; Chen, Ray T.

    2011-06-01

    We experimentally demonstrate a 300?m long silicon photonic crystal slot waveguide for on-chip near-infrared absorption spectroscopy. Based on the Beer-Lambert absorption law, our device combines slow light in photonic crystal waveguide with high electric field intensity in low-index 75nm wide slot, which effectively increases the optical absorption path length of the analyte. We demonstrate near-infrared absorption spectroscopy of xylene in water, independent of near-infrared absorption signatures of water, with a hydrophobic PDMS sensing phase that extracts xylene from water. Xylene concentrations up to 100ppb (parts per billion) (86?g/L) in water were measured.

  13. Grapevine water absorption in different soils. A spatio-temporal analysis.

    NASA Astrophysics Data System (ADS)

    Brillante, Luca; Bois, Benjamin; Lévêque, Jean; Mathieu, Olivier

    2015-04-01

    Hillslope vineyards show complex water dynamics between soil and plants. To gain further insight of this relationship, 8 grapevine plots were monitored during two vintages (2011-2013), on Corton Hill, Burgundy, France. Grapevine water status was monitored weekly by surveying water potential, and at harvest, using ?13C analysis of grape juice. Soil volumetric humidity was also measured weekly, using TDR probes. A pedotransfer function was developed to transform Electrical Resistivity Tomography (ERT) into Soil Volume Water and therefore to spatialise and describe variations in space and time in the Fraction of Transpirable Soil Water (FTSW). During the two years of monitoring, grapevines experienced great variation in water status, which ranged from low to substantial water deficit. With this freshly developed method, it was possible to observe differences in water absorption pattern by roots, in different soils, and at different depth. Great heterogeneity was observed, both laterally and vertically in grapevine water absorption. The contribution of each soil region to plant water status varies according to grapevine water status. It is different between day and night and depends from soil characteristics. It is to our knowledge the first time that water absorption by grapevine is revealed in space (2D) and time, and has therefore allowed a deeper comprehension of plant and soil dynamics in grapevine.

  14. 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.

  15. 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.

  16. Thermal transport coefficients for liquid and glassy water computed from a harmonic aqueous glass

    NASA Astrophysics Data System (ADS)

    Yu, Xin; Leitner, David M.

    2005-09-01

    We compute thermal transport coefficients for liquid and glassy water in terms of the vibrations of the quenched liquid. The thermal conductivity and thermal diffusivity are computed for H2O and D2O at densities from 0.93to1.2gcm-3. The computed thermal diffusivity of liquid water is in reasonable agreement with measured values and is found to increase with increasing temperature due largely to the thermal accessibility of delocalized librational modes. The influence of structure and density on the thermal conductivity of amorphous ices is investigated. The calculations reveal that density alone is unable to explain the measured thermal conductivity of amorphous ices, particularly low-density amorphous ices, for which the thermal conductivity decreases with increasing temperature near 100K. To investigate the influence of structure on thermal transport in amorphous ices we have computed the thermal transport coefficients for low-density amorphous ices prepared in two different ways, one formed by quenching the liquid at 0.93gcm-3 and the other by distortion of cubic ice at the same density. The computed thermal conductivity of the latter is higher, but the structures of both forms are too disordered for the thermal conductivity to exhibit the unusual variation observed experimentally.

  17. 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.

  18. Temperature dependence of water-vapor absorption in the wing of the 183 GHz line

    Microsoft Academic Search

    A. Bauer; B. Duterage; M. Godon

    1986-01-01

    Absolute absorption rates of water vapor have been measured in the laboratory in the high-frequency wing of the 183 GHz line. Measurements have been carried out for pure water vapor and mixtures with N2 at atmospheric pressure. Pressure- and temperature-dependences are compared with models involving several types of lineshapes.

  19. Ammonia and ammonium hydroxide sensors for ammonia\\/water absorption machines: Literature review and data compilation

    Microsoft Academic Search

    N. C. Anheier Jr.; C. E. McDonald; J. M. Cuta; F. M. Cuta; K. B. Olsen

    1995-01-01

    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 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

  20. In vivo absorption comparison of nanotechnology-based silybin tablets with its water-soluble derivative.

    PubMed

    Xu, Di; Ni, Rui; Sun, Wei; Li, Luk Chiu; Mao, Shirui

    2015-04-01

    In this study, the in vivo oral absorption of a nanocrystal tablet formulation of a BCS II poorly water-soluble drug was compared with that of its water-soluble salt form. Silybin is used as the model drug, and its nanosuspension was prepared by high-pressure homogenization. Effect of process and formulation parameters on properties of the nansuspensions was investigated. Dried powder of the nanosuspension was prepared by spray drying and used for preparing tablets. A pharmacokinetic study was performed in Beagle dogs to compare the absorption for tablets of silybin nanocrystals and silybin meglumine. In vivo absorption of nanocrystal silybin tablet in Beagle dogs was determined. X-ray powder diffraction results indicated that silybin existed in a crystalline state after homogenization. In vivo absorption study in rats showed that the peroral absorption of silybin was enhanced remarkably by decreasing particle size. In vivo absorption of nanocrystal silybin tablet in Beagle dogs was comparable with that of the commercially available tablet of the water-soluble salt form of silybin. In conclusion, it is possible to increase the bioavailability of poorly soluble drugs by preparing its water-soluble derivative. PMID:24495272

  1. On the relative absorption strengths of water vapour in the blue wavelength range

    NASA Astrophysics Data System (ADS)

    Lampel, J.; Pöhler, D.; Tschritter, J.; Frieß, U.; Platt, U.

    2015-06-01

    In recent updates of the HITRAN water vapour H2O spectroscopic compilation covering the blue spectral region (here: 394-480 nm) significant changes for the absorption bands at 416 and 426 nm were reported. In order to investigate the consistency of the different cross-sections calculated from these compilations, H2O vapour column density ratios for different spectral intervals were retrieved from Long-path and Multi-Axis - Differential Optical Absorption Spectroscopy (DOAS) measurements. We observed a significant improvement of the DOAS evaluation when using the updated HITRAN water vapour absorption cross-sections for the calculation of the reference spectra. In particular the magnitudes of the residual spectra as well as the fit errors were reduced. However we also found that the best match between measurement and model is reached when the absorption cross-section of groups of lines are scaled by factors ranging from 0.5 and 1.9, suggesting that the HITRAN water vapour absorption compilation still needs significant corrections. For this spectral region we present correction factors for HITRAN 2009, HITRAN 2012, HITEMP and BT2 derived from field measurements. Additionally, upper limits for water vapour absorption in the UV-A range from 330-390 nm are given.

  2. 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.

  3. Temperature dependence of stream aeration coefficients and the effect of water turbulence: a critical review.

    PubMed

    Demars, B O L; Manson, J R

    2013-01-01

    The gas transfer velocity (K(L)) and related gas transfer coefficient (k(2) = K(L)A/V, with A, area and V, volume) at the air-water interface are critical parameters in all gas flux studies such as green house gas emission, whole stream metabolism or industrial processes. So far, there is no theoretical model able to provide accurate estimation of gas transfer in streams. Hence, reaeration is often estimated with empirical equations. The gas transfer velocity need then to be corrected with a temperature coefficient ? = 1.0241. Yet several studies have long reported variation in ? with temperature and 'turbulence' of water (i.e. ? is not a constant). Here we re-investigate thoroughly a key theoretical model (Dobbins model) in detail after discovering important discrepancies. We then compare it with other theoretical models derived from a wide range of hydraulic behaviours (rigid to free continuous surface water, wave and waterfalls with bubbles). The results of the Dobbins model were found to hold, at least theoretically in the light of recent advances in hydraulics, although the more comprehensive results in this study highlighted a higher degree of complexity in ?'s behaviour. According to the Dobbins model, the temperature coefficient ?, could vary from 1.005 to 1.042 within a temperature range of 0-35 °C and wide range of gas transfer velocities, i.e. 'turbulence' condition (0.005 < K(L) < 1.28 cm min(-1)). No other theoretical models showed any significant variability in ? with change in 'turbulence', and only modest variability in ? with change in temperature. However, the other theoretical models did not have the same temperature coefficient ? (with 1.000 < ? < 1.056 within 0-35 °C). A model integrating turbulence and bubble mediated gas transfer velocities suggested a lower temperature dependence for bubble (1.013water interface has still to be clarified, although many models simulate different flow conditions which may explain some of the observed discrepancies. We suggest that the temperature dependence curves produced by the Dobbins model may be used tentatively as a simple theoretical guide for streams with free surface water but not self-aerated flows encountered in whitewater rapids, cascades or weirs. Greater awareness of the different models and conditions of applications should help choosing an appropriate correction. Three case studies investigated the effect of the temperature coefficient on reaeration and stream metabolism (photosynthesis and respiration). In practice, the temperature correction may be an important parameter under constant turbulence conditions, but as the range in turbulence increases, the role of temperature may become negligible in determining K(L), whatever the temperature correction. The theoretical models reviewed here are also useful references to correct K(L) values determined using a reference tracer gas to a second species of interest. PMID:23123047

  4. Intestinal absorption of water-soluble vitamins in health and disease

    PubMed Central

    Said, Hamid M.

    2014-01-01

    Our knowledge of the mechanisms and regulation of intestinal absorption of water-soluble vitamins under normal physiological conditions, and of the factors/conditions that affect and interfere with theses processes has been significantly expanded in recent years as a result of the availability of a host of valuable molecular/cellular tools. Although structurally and functionally unrelated, the water-soluble vitamins share the feature of being essential for normal cellular functions, growth and development, and that their deficiency leads to a variety of clinical abnormalities that range from anaemia to growth retardation and neurological disorders. Humans cannot synthesize water-soluble vitamins (with the exception of some endogenous synthesis of niacin) and must obtain these micronutrients from exogenous sources. Thus body homoeostasis of these micronutrients depends on their normal absorption in the intestine. Interference with absorption, which occurs in a variety of conditions (e.g. congenital defects in the digestive or absorptive system, intestinal disease/resection, drug interaction and chronic alcohol use), leads to the development of deficiency (and sub-optimal status) and results in clinical abnormalities. It is well established now that intestinal absorption of the water-soluble vitamins ascorbate, biotin, folate, niacin, pantothenic acid, pyridoxine, riboflavin and thiamin is via specific carrier-mediated processes. These processes are regulated by a variety of factors and conditions, and the regulation involves transcriptional and/or post-transcriptional mechanisms. Also well recognized now is the fact that the large intestine possesses specific and efficient uptake systems to absorb a number of water-soluble vitamins that are synthesized by the normal microflora. This source may contribute to total body vitamin nutrition, and especially towards the cellular nutrition and health of the local colonocytes. The present review aims to outline our current understanding of the mechanisms involved in intestinal absorption of water-soluble vitamins, their regulation, the cell biology of the carriers involved and the factors that negatively affect these absorptive events. PMID:21749321

  5. Intestinal absorption of water-soluble vitamins in health and disease.

    PubMed

    Said, Hamid M

    2011-08-01

    Our knowledge of the mechanisms and regulation of intestinal absorption of water-soluble vitamins under normal physiological conditions, and of the factors/conditions that affect and interfere with theses processes has been significantly expanded in recent years as a result of the availability of a host of valuable molecular/cellular tools. Although structurally and functionally unrelated, the water-soluble vitamins share the feature of being essential for normal cellular functions, growth and development, and that their deficiency leads to a variety of clinical abnormalities that range from anaemia to growth retardation and neurological disorders. Humans cannot synthesize water-soluble vitamins (with the exception of some endogenous synthesis of niacin) and must obtain these micronutrients from exogenous sources. Thus body homoeostasis of these micronutrients depends on their normal absorption in the intestine. Interference with absorption, which occurs in a variety of conditions (e.g. congenital defects in the digestive or absorptive system, intestinal disease/resection, drug interaction and chronic alcohol use), leads to the development of deficiency (and sub-optimal status) and results in clinical abnormalities. It is well established now that intestinal absorption of the water-soluble vitamins ascorbate, biotin, folate, niacin, pantothenic acid, pyridoxine, riboflavin and thiamin is via specific carrier-mediated processes. These processes are regulated by a variety of factors and conditions, and the regulation involves transcriptional and/or post-transcriptional mechanisms. Also well recognized now is the fact that the large intestine possesses specific and efficient uptake systems to absorb a number of water-soluble vitamins that are synthesized by the normal microflora. This source may contribute to total body vitamin nutrition, and especially towards the cellular nutrition and health of the local colonocytes. The present review aims to outline our current understanding of the mechanisms involved in intestinal absorption of water-soluble vitamins, their regulation, the cell biology of the carriers involved and the factors that negatively affect these absorptive events. PMID:21749321

  6. 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

  7. Effect of alpha-glucosidehydrolase inhibition and intestinal absorption of sucrose, water, and sodium in man.

    PubMed Central

    Caspary, W F; Kalisch, H

    1979-01-01

    The effect of a new complex oligosaccharide exhibiting potent inhibitory action on alpha-glucoside hydrolases on intestinal absorption of sucrose in man was tested by constant in vivo perfusion of the jejunum. At concentrations of 4.65 or 15.5 X 10(-6)M the alpha-glucosidehydrolase inhibitor (alpha-GHI) markedly inhibited absorption of glucose from sucrose and absorption of sodium and water. Oral administration of the alpha-GHI resulted as well in depression of solute, sodium, and water absorption. This new compound can serve as an interesting tool to induce carbohydrate malabsorption by inhibition of final digestion and may possibly be of beneficial therapeutic effect in dietary control of diabetes or obesity. PMID:387540

  8. 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...

  9. Effect of Water Absorption on the Mechanical Properties of Sisal and Jute Fiber Composites

    Microsoft Academic Search

    F. H. M. M. Costa; J. R. M. DAlmeida

    1999-01-01

    The variation of the ultimate stress and the elastic modulus of four different natural fiber-resin matrix composites was evaluated as a function of the aging of these composites in distilled water. Their diffusion coefficients and the maximum water content were also determined by fitting the experimental data to the Fickian model for diffusion. The composites analyzed were the common jute-

  10. Foliar absorption of intercepted rainfall improves woody plant water status most during drought.

    PubMed

    Breshears, David D; McDowell, Nathan G; Goddard, Kelly L; Dayem, Katherine E; Martens, Scott N; Meyer, Clifton W; Brown, Karen M

    2008-01-01

    A large proportion of rainfall in dryland ecosystems is intercepted by plant foliage and is generally assumed to evaporate to the atmosphere or drip onto the soil surface without being absorbed. We demonstrate foliar absorption of intercepted rainfall in a widely distributed, continental dryland, woody-plant genus: Juniperus. We observed substantial improvement in plant water status, exceeding 1.0 MPa water potential for drought-stressed plants, following precipitation on an experimental plot that excluded soil water infiltration. Experiments that wetted shoots with unlabeled and with isotopically labeled water confirmed that water potential responded substantially to foliar wetting, that these responses were not attributable to re-equilibration with other portions of the xylem, and that magnitude of response increased with water stress. Foliar absorption is not included in most ecological, hydrological, and atmospheric models; has implications for interpreting plant isotopic signatures; and not only supplements water acquisition associated with increases in soil moisture that follow large or repeated precipitation events, but also enables plants to bypass soil water uptake and benefit from the majority of precipitation events, which wet foliage but do not increase soil moisture substantially. Foliar absorption of intercepted water could be more important than previously appreciated, especially during drought when water stress is greatest. PMID:18376545

  11. The phase behavior and absorption spectra of the ternary system cobaltous chloride-water-acetonitrile

    E-print Network

    Bobbitt, Jeffrey Lovett

    1967-01-01

    -Acetonitrile Solutions Prepared for Phase Diagram Determination . Density of Acetonitrile as 1'unction of Temperature BIBLIOGRAPHY 44 45 LIST OF TABLES A%3 FIGURZS TABLE 1 Activity Coefficients of Acetonitrile and Water in a Binary Solution 1'age TAB'Z 2 Pnase... to the discovery that only a very small amount oi' cobaltous chloride was required to "salt-out" an acetonitrile- water mixture. The binary solvent system acetonitrile-water has been studied by Othmer and Josefowits who have reported ?8 activity coefficients...

  12. Concentration-dependent absorption of aluminum in rats exposed to labile aluminum in drinking water.

    PubMed

    Glynn, A W; Sparén, A; Danielsson, L G; Sundström, B; Jorhem, L

    1999-04-01

    The hypothesis was tested that the absorption of labile Al in rats will increase when the Al-binding capacity of food components in the stomach is saturated. Male rats were exposed to 0, 10, 50, or 500 mg labile Al/L in acidic drinking water (pH 3) for 9 wk. The results show that labile Al in drinking water is complexed by feed constituents in the stomach of the rat in vivo, thus causing a nondetectable absorption of Al at 10 mg Al/L. An increased absorption of Al at 50 and 500 mg Al/L was associated with a saturation of the Al-binding capacity of feed components in the lumen of the stomach, causing the appearance of labile Al. Thus, the presence of labile Al in drinking water does not necessarily result in a high Al absorption when the water is ingested, since the bioavailability of labile Al is dependent both on the amount and composition of Al-binding components present in the gastrointestinal tract at the time of ingestion of the water. It is thus not possible to predict the body burden of Al in humans just by measuring the Al concentrations in drinking water. Even a further refining of the exposure measurement to include speciation of Al in the water may not markedly improve the prediction of the Al body burden. Future epidemiological studies must therefore be based on actual measurements of Al concentration in tissues or fluids from the study subjects. PMID:10201636

  13. Local effects in the X-ray absorption spectrum of salt water

    Microsoft Academic Search

    Eric Schwegler; Heather Kulik; Nicola Marzari; Alfredo Correa; David Prendergast; Giulia Galli

    2011-01-01

    We have used first principles molecular dynamics and theoretical X-ray absorption spectroscopy (XAS) to investigate the aqueous solvation of cations in MgCl2, CaCl2, and NaCl solutions. We focus our discussion on the species-specific effects that Mg^2+, Ca^2+, and Na^+ have on the X-ray absorption spectrum of the respective solutions. For the divalent cations, we find that the water molecules that

  14. Determination of the bulk moisture diffusion coefficient for corn starch using an automated water sorption instrument.

    PubMed

    Yu, Xin; Schmidt, Arthur R; Bello-Perez, Luis A; Schmidt, Shelly J

    2008-01-01

    The bulk moisture diffusion coefficient (Db) is an important physical parameter of food ingredients and systems. However, the traditional method of measuring Db using saturated salt solutions is very time-consuming and cumbersome. New automated water sorption instruments, which can be used to conveniently and precisely control both relative humidity and temperature, provide a faster, more robust method for collecting the data needed for determining Db. Thus, the objectives of this study were to (1) investigate the use of the DVS instrument for collecting the data needed for determining the adsorption (Dba) and desorption (Dbd) bulk moisture diffusion coefficients for dent corn starch as a function of relative humidity and (2) determine the effect of temperature on Dba for dent corn starch at a constant relative humidity. Kinetic water sorption profiles of dent corn starch were obtained at eight relative humidity values ranging from 10 to 80% at 10% intervals at 25 degrees C and at five temperatures, 15, 20, 25, 30, and 35 degrees C, at 50% relative humidity using a DVS instrument. Db was calculated from the kinetic water sorption profiles using the full solution of Fick's second law for the thin slab model, as well as the slope method, a simplification of the full model. The Dba of dent corn starch at 25 degrees C reached a maximum at intermediate relative humidity values, after which Dba decreased due to a change in the moisture diffusion mechanism from vapor to liquid diffusion. The Dbd of dent corn starch at 25 degrees C remained nearly constant as a function of relative humidity. The Dba for dent corn starch increased as temperature increased from 15 to 35 degrees C, with an activation energy of 38.85 +/- 0.433 kJ/mol. PMID:18078318

  15. Transpiration, Water Absorption, and Internal Water Balance of Cotton Plants as Affected by Light and Changes in Saturation Deficit 1

    PubMed Central

    Ehrler, W. L.; van Bavel, C. H. M.; Nakayama, F. S.

    1966-01-01

    In controlled environment studies of cotton plants (Gossypium barbadense L.) a light-induced acceleration of transpiration upset the water balance established in the dark because of a lag in water absorption. A plant-water deficit could be generated either by sudden illumination at a given saturation deficit (sd) of the air, or by raising the sd in conjunction with illumination, without different effects. Direct water balance measurements were confirmed in every experiment by beta ray gauge detection of changes in leaf-water content resulting from unequal gain and loss of water by the whole plant. Recovery from the initial loss of turgidity always was faster and more complete at the higher than at the lower values of sd. Recovery occurred even in the light at the higher values of sd, but was enhanced by return to darkness and a lower sd, which at times resulted in superhydration. Rehydration in the light could be attributed to at least 2 processes: A) a diminished transpiration rate if earlier water loss was sufficient to induce stomatal closure, and B) an increased rate of water absorption. The data suggest that a water deficit, temporary or persisting, does not cause a significantly lowered transpiration rate; thus, recovery must depend on increased absorption. The communicative link between the 2 processes appears weak, transmitting strong signals only. PMID:16656235

  16. Photonic crystal slot waveguide absorption spectrometer for on-chip near-infrared spectroscopy of xylene in water

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Cheng; Chakravarty, Swapnajit; Wang, Xiaolong; Lin, Cheyun; Chen, Ray T.

    2011-01-01

    We experimentally demonstrate a 300 ?m long silicon photonic crystal slot waveguide near-infrared absorption spectrometer. Based on Beer-Lambert absorption law, our on-chip absorption spectrometer combines slow light in a photonic crystal waveguide with a high electric field intensity in a low-index 75 nm wide slot, which effectively increases the optical absorption path length of the analyte. We demonstrate near-infrared absorption spectroscopy of xylene in water, with a polydimethyl siloxane sensing phase for xylene extraction from water. Xylene concentrations up to 100 ppb (parts per billion) (86 ?g/l) in water were measured.

  17. 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.

  18. Donor impurity-related linear and nonlinear intraband optical absorption coefficients in quantum ring: effects of applied electric field and hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Barseghyan, Manuk G.; Restrepo, Ricardo L.; Mora-Ramos, Miguel E.; Kirakosyan, Albert A.; Duque, Carlos A.

    2012-09-01

    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.

  19. 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.

  20. Variability in light absorption and scattering of phytoplankton in Patagonian waters: Role of community size structure and

    E-print Network

    Stramski, Dariusz

    scattering coefficients during such blooms on the basis of field data. The chlorophyll-a concentration, [Chla% of samples were dominated by nanophytoplankton (N-group) and 20% by microphytoplankton (M-group). Chlorophyll-specific phytoplankton absorption coefficients at 440 and 676 nm, a*ph(440) and a*ph(676), and particulate scattering

  1. Evaluation of suitable spectral intervals for near-IR laboratory detection of water vapour continuum absorption

    NASA Astrophysics Data System (ADS)

    Ptashnik, Igor V.

    2007-11-01

    The water vapour continuum absorption is an important component of molecular absorption of radiation in atmosphere. However, uncertainty in knowledge of the value of the continuum absorption at present can achieve 100% in different spectral regions leading to an error in flux calculation up to 3 5 W/m2 global mean. This work uses line-by-line calculations to reveal the best spectral intervals for experimental verification of the CKD water vapour continuum models in the currently least-studied near-infrared spectral region. Possible sources of errors in continuum retrieval taken into account in the simulation include the sensitivity of laboratory spectrometers and uncertainties in the spectral line parameters in HITRAN-2004 and Schwenke Partridge database. It is shown that a number of micro-windows in near-IR can be used at present for laboratory detection of the water vapour continuum with estimated accuracy from 30% to 5%.

  2. Optimizing Thermal-Optical Analysis for Atmospheric Black Carbon (BC): Determining the Beer-Lambert Mass Without a Fixed Mass Absorption Coefficient for BC

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Norris, G.

    2007-12-01

    In thermal-optical transmission analysis (TOT), laser light passing through a particle-laden filter is monitored while carbonaceous material is removed in several heating steps and measured by flame ionization detection. In a helium atmosphere, the laser signal is attenuated by the pyrolysis of organic carbon (OC). Later, while carbon is removed in an oxidizing atmosphere, the laser signal returns to its value prior to pyrolysis (split point), whereupon the amount of carbon equivalent to the native BC is measured. Since pyrolyzed OC may actually evolve beyond the split point, the specific absorption cross sections of pyrolyzed OC and native BC must be equivalent. Moreover, OC pyrolysis must be sufficient so that unpyrolyzed OC is not measured as BC beyond the split point. Using response surfaces models of the apparent specific absorption cross sections for pyrolyzed OC and what the instrument measures as native BC, we determined the thermal conditions for establishing the equivalence of the apparent cross sections while insuring sufficient pyrolysis of OC. In this way, we have optimized TOT for BC mass based on the Beer-Lambert Law but without the need for an absolute mass absorption coefficient (or an absolute attenuation coefficient) for BC. Optimal thermal conditions for the equivalence of the cross sections were indicated by the intersection of the response surfaces. Concurrently, optimal conditions for sufficient pyrolysis of OC were indicated by a plateau in the response surface for the BC cross section. Modeling was based on extensive analyses of PM2.5 samples collected from Atlanta, Los Angeles, and Seattle. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

  3. Modeling the vertical distributions of downwelling plane irradiance and diffuse attenuation coefficient in optically deep waters

    NASA Astrophysics Data System (ADS)

    Pan, Xiaoju; Zimmerman, Richard C.

    2010-08-01

    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 sky irradiance with the knowledge of sky and water conditions. The percent root mean square errors (RMSE) for the vertical distribution of Ed(z) under various sky and water conditions between PZ06 and Hydrolight results are typically less than 4%. Field observations from the southern Middle Atlantic Bight (SMAB) and global in situ data set (NOMAD) also confirmed the validity of PZ06 in reproducing Kd. PZ06 provides an alternative and improvement to the simpler models (e.g., Gordon, 1989; and Kirk, 1991) and an operational ocean color algorithm, while the latter two kinds of models are valid to limited sky and water conditions. PZ06 can be applied to study Kd from satellite remotely sensed images and seems to improve Kd derivation over current operational ocean color algorithm.

  4. Partition coefficients of 1-alkanols between water and DDAB vesicle membrane determined by differential conductivity method.

    PubMed

    Kawamura, Hideo; Manabe, Masahiro; Myoujou, Masako; Katsuura, Hajime; Shiomi, Masaki

    2009-01-01

    The partition coefficients of 1-alkanols between water and didodecyldimethylammonium bromide (DDAB) vesicle membrane, and the change of the degree of counter-ion dissociation on DDAB vesicle caused by the solubilization of 1-alkanols were determined from electric conductivity measurements. A good linear relationship was obtained between logarithmic value of the partition coefficient and carbon number of alkyl chain in 1-alkanols. The standard transfer free energy change per methylene group was evaluated from the slope of this straight line. On the other hand, the effect of 1-alkanols on the degree of counter-ion dissociation was independent of carbon number of 1-alkanols. Comparing the results of the present system with those of sodium dodecylsulfate (SDS) micelle/1-alkanol system, it was found that the interior of DDAB vesicle membrane is more hydrophobic than that of SDS micelles. Furthermore, the increase in counter-ion dissociation caused by solubilized 1-alkanols was much lesser for DDAB vesicles than SDS micelles. PMID:19282640

  5. Mechanisms of guanylin action on water and ion absorption at different regions of seawater eel intestine.

    PubMed

    Ando, Masaaki; Wong, Marty K S; Takei, Yoshio

    2014-09-15

    Guanylin (GN) inhibited water absorption and short-circuit current (Isc) in seawater eel intestine. Similar inhibition was observed after bumetanide, and the effect of bumetanide was abolished by GN or vice versa, suggesting that both act on the same target, Na(+)-K(+)-2Cl(-) cotransporter (NKCC), which is a key player for the Na(+)-K(+)-Cl(-) transport system responsible for water absorption in marine teleost intestine. However, effect of GN was always greater than that of bumetanide: 10% greater in middle intestine (MI) and 40% in posterior intestine (PI) for Isc, and 25% greater in MI and 34% in PI for water absorption. After treatment with GN, Isc decreased to zero, but 20-30% water absorption still remained. The remainder may be due to the Cl(-)/HCO3 (-) exchanger and Na(+)-Cl(-) cotransporter (NCC), since inhibitors for these transporters almost nullified the remaining water absorption. Quantitative PCR analysis revealed the presence of major proteins involved in water absorption; the NKCC2? and AQP1 genes whose expression was markedly upregulated after seawater acclimation. The SLC26A6 (anion exchanger) and NCC? genes were also expressed in small amounts. Consistent with the inhibitors' effect, expression of NKCC2? was MI > PI, and that of NCC? was MI < PI. The present study showed that GN not only inhibits the bumetanide-sensitive Na(+)-K(+)-Cl(-) transport system governed by NKCC2?, but also regulates unknown ion transporters different from GN-insensitive SLC26A6 and NCC. A candidate is cystic fibrosis transmembrane conductance regulator Cl(-) channel, as demonstrated in mammals, but its expression is low in eel intestine, and its role may be minor, as indicated by the small effect of its inhibitors. PMID:24990857

  6. Diode laser absorption spectroscopy of water vapor in a scramjet combustor.

    PubMed

    Griffiths, Alan D; Houwing, A Frank P

    2005-11-01

    A sensor based on tunable diode laser absorption spectroscopy was constructed for time-resolved temperature and water vapor concentration measurements in a scramjet combustor. The sensor probed two absorption lines near 1390 nm with two time-multiplexed lasers used to measure temperature and water vapor concentration at up to 20 kHz. A demonstration experiment was performed in the supersonic, expanding exhaust region of the combustor, showing the measurement to be repeatable, able to resolve temporal trends during tunnel operation, and sensitive to changes in combustor operating conditions. PMID:16270554

  7. The Effect of Heat on Structural Characteristics and Water Absorption Behavior of Agave Fibers

    NASA Astrophysics Data System (ADS)

    Saikia, Dip

    2008-04-01

    The structural characteristics and water absorptions behavior agave fibers were investigated over a range of temperature by using XRD, IR, TG and gravimetric methods. Three distinct thermal processes were observed during heating the fiber in the temperature range 310-760 K in air, oxygen and nitrogen invariably. The cellulose structures of the fibers were unaffected on heating up to 450 K. The samples showed thermal decomposition processes beyond 500 K. Fibers displayed a two-stage diffusion behavior. The structural parameters and kinetic of water absorption of the fibers at specific temperatures were analyzed.

  8. 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...

  9. Transfer Coefficients of Momentum, Heat and Water Vapour in the Atmospheric Surface Layer of a Large Freshwater Lake

    NASA Astrophysics Data System (ADS)

    Xiao, Wei; Liu, Shoudong; Wang, Wei; Yang, Dong; Xu, Jiaping; Cao, Chang; Li, Hanchao; Lee, Xuhui

    2013-09-01

    In studies of lake-atmosphere interactions, the fluxes of momentum, water vapour and sensible heat are often parametrized as being proportional to the differences in wind, humidity and air temperature between the water surface and a reference height above the surface. Here, the proportionality via transfer coefficients in these relationships was investigated with the eddy-covariance method at three sites within an eddy-covariance mesonet across Lake Taihu, China. The results indicate that the transfer coefficients decreased with increasing wind speed for weak winds and approached constant values for strong winds. The presence of submerged macrophytes reduced the momentum transfer (drag) coefficient significantly. At the two sites free of submerged macrophytes, the 10-m drag coefficients under neutral stability were 1.8 and at the wind speed of , which are 38 and 34 % greater than the prediction by the Garratt model for the marine environment.

  10. 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.

  11. 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.

  12. Polyparameter linear free energy relationship for wood char-water sorption coefficients of organic sorbates.

    PubMed

    Plata, Desiree L; Hemingway, Jordon D; Gschwend, Philip M

    2015-07-01

    Black carbons, including soots, chars, activated carbons, and engineered nanocarbons, have different surface properties, but the extent to which these affect their sorbent properties is not known. To evaluate this for an environmentally ubiquitous form of black carbon, biomass char, the surface of a well-studied wood char was probed using 14 sorbates exhibiting diverse functional groups, and the data were fit with a polyparameter linear free energy relationship to assess the importance of the various possible sorbate-char surface interactions. Sorption from water to water-wet char evolved with the sorbate's degree of surface saturation and depended on only a few sorbate parameters: log Kd (L/kg) = [(4.03 ± 0.14) + (-0.15 ± 0.04) log ai ] V + [(-0.28 ± 0.04) log ai ] S + (-5.20 ± 0.21) B, where ai is the aqueous saturation of the sorbate i, V is McGowan's characteristic volume, S reflects polarity, and B represents the electron-donation basicity. As is generally observed for activated carbon, the sorbate's size encouraged sorption from water to the char, whereas its electron donation and proton acceptance discouraged sorption from water. The magnitude and saturation dependence differed significantly from what has been seen for activated carbons, presumably reflecting the unique surface chemistries of these 2 black carbon materials and suggesting that black carbon-specific sorption coefficients will yield more accurate assessments of contaminant mobility and bioavailability, as well as evaluation of a site's response to remediation. Environ Toxicol Chem 2015;34:1464-1471. © 2015 SETAC. PMID:25708318

  13. 1Octanol\\/Water Partition Coefficients of 5 Pharmaceuticals from Human Medical Care: Carbamazepine, Clofibric Acid, Diclofenac, Ibuprofen, and Propyphenazone

    Microsoft Academic Search

    Traugott Scheytt; Petra Mersmann; Ralph Lindstädt; Thomas Heberer

    2005-01-01

    Laboratory studies were conducted to characterize the 1-octanol\\/water partition coefficients of pharmaceutically active substances carbamazepine, clofibric acid, diclofenac, ibuprofen, and propyphenazone. Partition coefficients determined by shake flask experiments (OECD guideline 107) varied between log KOW 1.51 for carbamazepine, 2.88 for clofibric acid, 1.90 for diclofenac, 2.48 for ibuprofen, and 2.02 for propyphenazone. Comparison of these values with the literature values

  14. Near-infrared diode laser absorption diagnostic for temperature and water vapor in a scramjet combustor.

    PubMed

    Liu, Jonathan T C; Rieker, Gregory B; Jeffries, Jay B; Gruber, Mark R; Carter, Campbell D; Mathur, Tarun; Hanson, Ronald K

    2005-11-01

    Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34-1.47 microm spectral region (2v1 and vl + v3 overtone bands). Ratio thermometry was performed using direct-absorption wavelength scans of isolated features at a 4-kHz repetition rate, as well as 2f wavelength modulation scans at a 2-kHz scan rate. Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise. Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity. The use of three water vapor absorption features allowed for preliminary estimates of temperature distributions along the line of sight. The improved signal quality afforded by 2f measurements, in the case of weak absorption, demonstrates the utility of a scanned wavelength modulation strategy in such situations. PMID:16270559

  15. Near-infrared diode laser absorption diagnostic for temperature and water vapor in a scramjet combustor

    SciTech Connect

    Liu, Jonathan T.C.; Rieker, Gregory B.; Jeffries, Jay B.; Gruber, Mark R.; Carter, Campbell D.; Mathur, Tarun; Hanson, Ronald K

    2005-11-01

    Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34-1.47 {mu}m spectral region (2v1and v1+ v3overtone bands). Ratio thermometry was performed using direct-absorption wavelength scans of isolated features at a 4-kHz repetition rate, as well as 2f wavelength modulation scans at a 2-kHz scan rate. Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise. Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity. The use of three water vapor absorption features allowed for preliminary estimates of temperature distributions along the line of sight. The improved signal quality afforded by 2f measurements, in the case of weak absorption, demonstrates the utility of a scanned wavelength modulation strategy in such situations.

  16. Water vapor self-continuum absorption in near-infrared windows derived from laboratory measurements

    NASA Astrophysics Data System (ADS)

    Ptashnik, Igor V.; McPheat, Robert A.; Shine, Keith P.; Smith, Kevin M.; Williams, R. Gary

    2011-08-01

    In most near-infrared atmospheric windows, absorption of solar radiation is dominated by the water vapor self-continuum, and yet there is a paucity of measurements in these windows. We report new laboratory measurements of the self-continuum absorption at temperatures between 293 and 472 K and pressures from 0.015 to 5 atm in four near-infrared windows between 1 and 4 ?m (10000-2500 cm-1); the measurements are made over a wider range of wavenumbers, temperatures, and pressures than any previous measurements. They show that the self-continuum in these windows is typically one order of magnitude stronger than given in representations of the continuum widely used in climate and weather prediction models. These results are also not consistent with current theories attributing the self-continuum within windows to the far wings of strong spectral lines in the nearby water vapor absorption bands; we suggest that they are more consistent with water dimers being the major contributor to the continuum. The calculated global average clear-sky atmospheric absorption of solar radiation is increased by ˜0.75 W/m2 (which is about 1% of the total clear-sky absorption) by using these new measurements as compared to calculations with the MT_CKD-2.5 self-continuum model.

  17. Quantitative assessment of skin layers absorption and skin reflectance spectra simulation in the visible and near-infrared spectral regions

    Microsoft Academic Search

    Igor V Meglinski; Stephen J Matcher

    2002-01-01

    We have simulated diffuse reflectance spectra of skin by assuming a wavelength-independent scattering coefficient for the different skin tissues and using the known wavelength dependence of the absorption coefficient of oxy- and deoxyhaemoglobin and water. A stochastic Monte Carlo method is used to convert the wavelength-dependent absorption coefficient and wavelength-independent scattering coefficient into reflected intensity. The absorption properties of skin

  18. Solar spectral optical properties of pigments--Part I: model forderiving scattering and absorption coefficients from transmittance andreflectance measurements

    SciTech Connect

    Levinson, Ronnen; Berdahl, Paul; Akbari, Hashem

    2004-06-01

    Pigment characterization is performed by dispersing thepigment into a transparent film of refractive index 1.5, andmeasuringspectral transmittance and reflectance. Measurements of the filmreflectance backed with black and white substrates are also used. A modelfor extracting the spectral backscattering coefficient S and absorptioncoefficient K from spectrometer measurements is presented. Interfacereflectances complicate the model. The film's diffuse reflectance andtransmittance measurements are used to determine S and K as functions ofa model parameter sigma that represents the ratio of forward to totalscattering. Sigma is used to estimate the rate at which incidentcollimated light becomes diffuse, and is determined by fitting themeasured film reflectance backed by black. A typical value is sigma=0.8.Then, the measured film reflectance backed by white is compared with acomputed value as a self-consistency check. Measurements on severalcommon pigments are used to illustrate the method.

  19. 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.

  20. Broadband microwave absorption spectrometer for liquid media

    SciTech Connect

    Mukherjee, P.; Gosnell, T.R.; Bigio, I.J.

    1988-12-01

    A broadband, continuous-sweep microwave spectrometer has been constructed for measurements of the absorption coefficient of aqueous solutions and other liquid media. The spectrometer makes use of the phase fluctuation optical heterodyne technique, which provides a direct measure of the microwave power deposited in the sample. Consequently, in contrast to the standard dielectrometric techniques that indirectly determine the absorption coefficient via separate measurements of the real and imaginary parts of the dielectric constant, this spectrometer directly measures the microwave absorption coefficient. Broadband spectra are obtained using a transmission line to couple microwave power into the liquid sample. The absorption spectrum for deionized water in the range 3--20 GHz is presented as an example and shows excellent agreement with calculated values of the absorption coefficient based on previously published dielectric data.

  1. Octanol-Water Partition Coefficient from 3D-RISM-KH Molecular Theory of Solvation with Partial Molar Volume Correction.

    PubMed

    Huang, WenJuan; Blinov, Nikolay; Kovalenko, Andriy

    2015-04-30

    The octanol-water partition coefficient is an important physical-chemical characteristic widely used to describe hydrophobic/hydrophilic properties of chemical compounds. The partition coefficient is related to the transfer free energy of a compound from water to octanol. Here, we introduce a new protocol for prediction of the partition coefficient based on the statistical-mechanical, 3D-RISM-KH molecular theory of solvation. It was shown recently that with the compound-solvent correlation functions obtained from the 3D-RISM-KH molecular theory of solvation, the free energy functional supplemented with the correction linearly related to the partial molar volume obtained from the Kirkwood-Buff/3D-RISM theory, also called the "universal correction" (UC), provides accurate prediction of the hydration free energy of small compounds, compared to explicit solvent molecular dynamics [ Palmer , D. S. ; J. Phys.: Condens. Matter 2010 , 22 , 492101 ]. Here we report that with the UC reparametrized accordingly this theory also provides an excellent agreement with the experimental data for the solvation free energy in nonpolar solvent (1-octanol) and so accurately predicts the octanol-water partition coefficient. The performance of the Kovalenko-Hirata (KH) and Gaussian fluctuation (GF) functionals of the solvation free energy, with and without UC, is tested on a large library of small compounds with diverse functional groups. The best agreement with the experimental data for octanol-water partition coefficients is obtained with the KH-UC solvation free energy functional. PMID:25844645

  2. Measurement of lead in drinking water by atomic absorption spectrometry with Dithizone extraction

    Microsoft Academic Search

    Guo Dong Mao; Craig C. Foreback

    1997-01-01

    A rapid and reproducible procedure is described for pre?concentrating lead in drinking water. 10 ml of water sample is adjusted to alkaline pH and extracted with 5 ml of 0.01% dithizone in chloroform. Chloroform phase is then washed and evaporated to dryness. Dithizone chelated lead is re?extracted into 2 ml of 5% HNO3 and analyzed by Perkin?Elmer atomic absorption spectrometer

  3. EFFECT OF WATER ABSORPTION, POROSITY AND SORPTIVITY ON DURABILITY OF GEOPOLYMER MORTARS

    Microsoft Academic Search

    Suresh Thokchom; Partha Ghosh; Somnath Ghosh

    An experimental program was carried out to study the effect of water absorption, apparent porosity and sorptivity on durability of fly ash based geopolymer mortar specimens in sulphuric acid solution. Low calcium Class F fly ash was activated by a mixture of NaOH and Na2SiO3 containing 5% to 8% Na2O with water to fly ash ratio of 0.33.The durability of

  4. Preliminary observations of water movement in cement pastes during curing using X-ray absorption

    Microsoft Academic Search

    D. P Bentz; K. K Hansen

    2000-01-01

    X-ray absorption and concurrent mass measurements are used in quantifying water movement in 4 to 5 mm thick cement paste specimens with their top surface exposed to drying. Experimental variables examined in this preliminary study include water-to-cement (w\\/c) ratio and open vs. capped samples. Layered specimens (e.g., 0.3 w\\/c ratio paste over 0.45 w\\/c ratio paste) are also examined to

  5. 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.

  6. Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

    E-print Network

    Elles, Christopher G.; Rivera, Christopher A.; Zhang, Yuyuan; Pieniazek, Piotr A.; Bradforth, Stephen E.

    2009-02-26

    Two-photon absorption (2PA) spectroscopy in the range from 7 to 10 eV provides new insight on the electronic structure of liquid water. Continuous 2PA spectra are obtained via the pump-probe technique, using broadband probe pulses to record...

  7. Water absorption and porosity of repair mortars used in loss compensation in Hungary

    NASA Astrophysics Data System (ADS)

    Török, Ákos; Szemerey-Kiss, Balázs

    2015-04-01

    The water absorption properties and porosity of repair mortars were studied under laboratory conditions. Commercially available repair mortars and laboratory made mixtures containing different binder aggregate ratio were prepared. The main aim of this study was to compare the hygric properties of repair mortars and porous Hungarian limestone in order to assess their compatibility. 50% of limestone aggregate of 1-2 mm in size, was added to both the commercially available repair mortars and to the laboratory mixtures. Water absorption properties of the pure repair mortars were compared to the ones with aggregate and to the ones of the porous limestone. Porosity of the pure porous limestone was in the order of 33-36 wt%, while that of the pure repair mortars were in between 25-30%. Experiments aimed to increase the porosity of the repair mortars by adding aggregate. Studied repair mortars with 50% of porous limestone aggregate had still much lower water absorption than that of the porous limestone with one exception. With adding aggregates the porosity of repair mortars increased but the pore-size distribution was not shifted to the macro-pore range that is a typical feature of the porous limestone. Thus the water absorption properties of the repair mortars did not show appropriate change even after adding porous limestone as an aggregate.

  8. Alpha and beta adrenergic agonists stimulate water absorption in the rat proximal tubule

    Microsoft Academic Search

    Edward J. Weinman; Steven C. Sansom; Thomas F. Knight; Harry O. Senekjian

    1982-01-01

    Summary Simultaneous capillary and luminal microperfusion studies were performed in the rat proximal tubule to determine the effects of the beta agonist isoproterenol and the alpha agonist phenylephrine on water absorption. Capillary and luminal perfusion solutions were composed such that organic solutes were not present, no bicarbonate was present in the lumen, and no chloride gradient was imposed. Under such

  9. Ultraviolet-visible absorptive features of water extractable and humic fractions of animal manure and compost

    Technology Transfer Automated Retrieval System (TEKTRAN)

    UV-vis spectroscopy is a useful tool for characterizing water extractable or humic fractions of natural organic matter (WEOM). Whereas the whole UV-visible spectra of these fractions are more or less featureless, the specific UV absorptivity at 254 and 280 nm as well as spectral E2/E3 and E4/E6 rat...

  10. Radiation modification of water absorption of cassava starch by acrylic acid/acrylamide

    NASA Astrophysics Data System (ADS)

    Kiatkamjornwong, Suda; Chomsaksakul, Wararuk; Sonsuk, Manit

    2000-10-01

    Graft copolymerizations of acrylamide and/or acrylic acid onto cassava starch by a simultaneous irradiation technique using gamma-rays as the initiator were studied with regard to various parameters of importance: the monomer-to-cassava starch ratio, total dose (kGy), dose rate (kGy h -1), acrylamide-to-acrylic acid ratio, and the addition of nitric acid and maleic acid as the additives. Grafting parameters were determined in relation to the water absorption of the saponified graft copolymer. The water absorption of the saponified graft copolymer in salt and buffer solutions of different ionic strengths was also measured, from which the superabsorbent properties are found to be pH sensitive. The starch graft copolymers of acrylamide and acrylic acid give higher water absorption than the starch graft copolymers of either acrylamide or acrylic acid alone. The porosity of the saponified starch graft copolymers prepared by the acrylamide/acrylic acid ratios of 70:30 and 50:50 was much higher than the porosity of copolymers in terms of fine networks. Ionic strength and multi-oxidation states of the saline and buffer solutions markedly decreased the water absorption of the saponified cassava starch grafted superabsorbent polymers.

  11. 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...

  12. Atmospheric water vapor estimate by a differential absorption technique with the POLDER instrument

    Microsoft Academic Search

    S. Bouffies; D. Tanre; F. M. Breon; P. Dubuisson

    1995-01-01

    The POLDER (polarization and directionality of the earth reflectances) instrument, to be launched in 1996 on the Japanese ADEOS platform, includes a channel which covers the 910 nm water-vapor absorption band (near IR), as well as a channel at 865 nm. It is expected that the ratio of the two reflectance measurements can yield an estimate of the total atmospheric

  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. Simulation of solar lithium bromide–water absorption cooling system with parabolic trough collector

    Microsoft Academic Search

    M. Mazloumi; M. Naghashzadegan; K. Javaherdeh

    2008-01-01

    Ahwaz is one of the sweltering cities in Iran where an enormous amount of energy is being consumed to cool residential places in a year. The aim of this research is to simulate a solar single effect lithium bromide–water absorption cooling system in Ahwaz. The solar energy is absorbed by a horizontal N–S parabolic trough collector and stored in an

  15. Improving Atmospheric Correction for Visible/Short Wave Infrared (VSWIR) Imaging Spectrometers with Iterative Fitting of Absorption By Three Phases of Water

    NASA Astrophysics Data System (ADS)

    Pennington, E. A.; Thompson, D. R.; Green, R. O.; Gao, B. C.

    2014-12-01

    Airborne imaging spectrometers like the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) offer valuable insight into the Earth's terrestrial and ocean ecosystems, mineralogy, and land use. Estimating surface reflectance requires accounting for atmospheric absorption, which is sensitive to the local abundance of water vapor. Analysts typically estimate water vapor concentrations using the depths of absorption features, which can be inaccurate by up to 50% over surface features containing liquid water or ice. This can bias the retrieved water vapor maps and create atmospheric artifacts in reflectance spectra. A new retrieval method offers significant accuracy improvements over plant canopies or ice by estimating the path lengths of all three phases of water simultaneously, adjusting absorptions to best fit the measurement over a broader spectral interval. This paper assesses the remaining sources of error for the three-phase retrieval technique. We analyze retrievals for synthetic data when the 940 and 1140 nm wavelength features are fitted, for initial vapor path estimates ranging from 0 to ±50% accuracy. These tests indicate that most error comes from inaccuracy in the initial path estimate used to obtain vapor absorption coefficients. We evaluate a modified algorithm that uses multiple iterations to refine this estimate. Error is found to approach a constant value, demonstrating improved robustness to initialization conditions. We also assess the new iterative method using corrected AVIRIS data over various environments. The iterative method yields significantly better water vapor maps, reducing spurious correlations between vegetation canopy water and vapor estimates. The new iterative method offers accuracy improvements over traditional Visible/Short Wave Infrared (VSWIR) atmospheric correction methods, at modest computational cost.

  16. Estimation of the Inherent Optical Properties of Natural Waters from the Irradiance Attenuation Coefficient and Reflectance in the Presence of Raman Scattering

    Microsoft Academic Search

    Hubert Loisel; Dariusz Stramski

    2000-01-01

    By means of radiative transfer simulations we developed a model for estimating the absorption a , the scattering b , and the backscattering b b coefficients in the upper ocean from irradiance reflectance just beneath the sea surface, R ( 0 ), and the average attenuation coefficient for downwelling irradiance, K d 1 , between the surface and the first

  17. The Water-Vapor Continuum Absorption in the Mid-Infrared Windows at Temperatures from 311 K to 363 K

    NASA Astrophysics Data System (ADS)

    Baranov, Yu. I.; Lafferty, W. J.

    2009-06-01

    The water-vapor continuum absorption in the mid-infrared 10 ?m and 4 ?m atmospheric windows plays an important role in the radiative balance of the Earth. We have derived the continuum absorption coefficients from spectra recorded at NIST with a resolution of 0.1 wn over a wide range of pressures from 2.8 kPa (21 torr) to 15.1 kPa (113 torr) and temperatures from 311 K to 363 K with path lengths ranging from 74 to 116 m. These measurements were performed with a BOMEM DA3-002 FTIR spectrometer with a 2 m base multi-pass cell. The spectral range was from 800 to 3500 wn . We have published the results obtained in the 10 ?m region recently. At the conditions given above, the continuum absorption in the higher frequency atmospheric window is quite detectable reaching as high as 4%. In order to avoid mistakes caused by the non-linear behavior of a MCT detector we later recorded an additional set of spectra with a highly-linear InSb detector. Both sets of spectra provide absorption coefficients coinciding within error bars. Our results around 5 ?m are in good agreement with those obtained from the widely used MT-CKD continuum model. However, at shorter wave lengths, the values diverge dramatically increasing up to one order of magnitude at the center of the window. Despite the comparatively large uncertainties of our data, comparison with all other available results leads us to the conclusion that the MT-CKD model greatly underestimates the self-broadened continuum over the 4 ?m atmospheric window. We have also extended our measurements to lower frequencies with the use of KRS-5 cell windows. The current spectral range is down to 600 wn. Yu. I. Baranov, W. J. Lafferty, Q. Ma, R. H. Tipping, JQSRT 109, 2291, (2008) S. A. Clough, F. X. Kneizys, and R. W. Davies, Atmos. Res. 23, 229, (1989)

  18. Predicting inhomogeneous water absorption in an ionic diblock polymer membrane

    NASA Astrophysics Data System (ADS)

    Herbst, Daniel; Witten, Thomas

    2013-03-01

    Fuel cells convert fuel directly into electrical power. Their performance depends on a permeable (yet strong) membrane to allow ion conduction (while preventing combustion). Anion-exchange membrane fuel-cells are especially economical to produce, but technological hurdles currently limit durability and OH- conductivity of the membrane. One solution to these problems is a diblock morphology. Layers of stiff hydrophobic polymer provide structure, while interspersed layers of polyelectrolyte provide avenues for conduction. Previously, little was known about the structure within the conducting layer. We adapted Scheutjens-Fleer polymer-brush theory to a lamellar geometry. The calculation tells where the polyelectrolytes congregate within a lamella, and hence how conduction occurs. This talk focuses on a new diblock material, PMB-PVBTMA. We show how the features of the material determine the intra-lamellar structure. We conclude that at low humidity, the bulkiness of PVBTMA causes it to adopt a near-uniform distribution within the conducting block. At high humidity, however, a phase separation may induce abrupt water channels. Understanding the architecture within the conducting layer will help guide research into better anion-exchange membranes materials. Fuel cells convert fuel directly into electrical power. Their performance depends on a permeable (yet strong) membrane to allow ion conduction (while preventing combustion). Anion-exchange membrane fuel-cells are especially economical to produce, but technological hurdles currently limit durability and OH- conductivity of the membrane. One solution to these problems is a diblock morphology. Layers of stiff hydrophobic polymer provide structure, while interspersed layers of polyelectrolyte provide avenues for conduction. Previously, little was known about the structure within the conducting layer. We adapted Scheutjens-Fleer polymer-brush theory to a lamellar geometry. The calculation tells where the polyelectrolytes congregate within a lamella, and hence how conduction occurs. This talk focuses on a new diblock material, PMB-PVBTMA. We show how the features of the material determine the intra-lamellar structure. We conclude that at low humidity, the bulkiness of PVBTMA causes it to adopt a near-uniform distribution within the conducting block. At high humidity, however, a phase separation may induce abrupt water channels. Understanding the architecture within the conducting layer will help guide research into better anion-exchange membranes materials. The authors would like to thank the Army Research Office for support of this research under the MURI #W911NF-10-1-0520.

  19. The impact of water flow configuration on crystallisation in LiBr/H2O absorption water heater

    SciTech Connect

    Wang, Kai [ORNL; Abdelaziz, Omar [ORNL; Vineyard, Edward Allan [ORNL

    2011-03-01

    Lithium Bromide (LiBr) strong solution entering the absorber tends to crystallise when the absorber temperature is increased for a fixed evaporating pressure. This is considered the key technical barrier for the development of a LiBr absorption heat pump water heater. There are several approaches to avoid the crystallisation problem, such as chemical crystallisation inhibitors, heat and mass transfer enhancement and thermodynamic cycle modification. This paper investigates and compares two flow configurations of LiBr absorption heat pump water heater to evaluate the allowable operating conditions for each. The simulation results indicated that introducing the process water through the absorber first results in lower absorber temperature and hence less tendency for crystallisation.

  20. Control of water absorption and its effect on interlaminar shear strength of CFRC with Al 2O 3 dispersion

    Microsoft Academic Search

    Manwar Hussain; Koichi Niihara

    1999-01-01

    In this study the effect of water absorption on interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composites (CFRC) and micro or nano sized Al2O3 particle dispersed carbon fiber hybrid reinforced composites (CFHRC) was investigated. Different weight change profiles were observed depending on experimental temperature and water absorption time. A clear drop of interlaminar shear strength was confirmed due

  1. An experimental integrated absorption heat pump effluent purification system. Part I: operating on water\\/lithium bromide solutions

    Microsoft Academic Search

    S. Santoyo-Gutiérrez; J. Siqueiros; C. L. Heard; E. Santoyo; F. A. Holland

    1999-01-01

    The merits of single stage absorption heat pumps coupled to simple distillation for effluent treatment are discussed. An experimental integrated absorption heat pump effluent purification system (IAHPEPS) was built and operated with water–lithium bromide as a working mixture. This unit has been used to raise the temperature and hence, the vapour pressure of the impure water contained in one vessel,

  2. Effect of curing agent polarity on water absorption and free volume in epoxy resin studied by PALS

    Microsoft Academic Search

    Junjun Wang; Jing Gong; Zhenli Gong; Xiaoli Yan; Bo Wang; Qili Wu; Shanjun Li

    2010-01-01

    Microstructure and water absorption were systematically studied by positron annihilation lifetime spectroscopy (PALS), gravimetric measurements and Differential Scanning Calorimetry (DSC) for epoxy resins DER331 (E51) cured with three different kinds of amine curing agents DDS, DDM and MOCA. Experimental results indicated that the water absorption as a function of immersed time could be well fitted to Fick’s second law. Based

  3. Solution of boundary heat transfer coefficients between hot stamping die and cooling water based on FEM and optimization method

    NASA Astrophysics Data System (ADS)

    Li, Huiping; He, Lianfang; Zhang, Chunzhi; Cui, Hongzhi

    2015-06-01

    The thermal physical parameters have significant effects on the calculation accuracy of physical fields, and the boundary heat transfer coefficient between the die and water is one of the most important thermal physical parameters in the hot stamping. In order to attain the boundary heat transfer coefficient, the testing devices and test procedures are designed according to the characteristic of heat transfer in the hot stamping die. A method of estimating the temperature-dependent boundary heat transfer coefficient is presented, and an inverse heat conduction software is developed based on finite element method, advance-retreat method and golden section method. The software is used to calculate the boundary heat transfer coefficient according to the temperatures measured by NiCr-NiSi thermocouples in the experiment. The research results show that, the convergence of the method given in the paper is well, the surface temperature of sample has a significant effect on the boundary heat transfer coefficient between the die and water. The boundary heat transfer coefficient increases as the surface temperature of sample reduces, and the variation is nonlinear.

  4. 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

  5. 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.

  6. Measurement methods in trace water vapor concentration detection system based on direct absorption spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    In trace water vapor direct absorption spectroscopy, the absorption signal is buried in noise and up and downs of the light intensity, an effective signal extraction method is vital. In the basis of double-beam differential absorption, division method in voltage and an approach based on balanced ratiometer detection (BRD) were studied. Voltage division has an excellent stability to temperature variation, mechanical extrusion and fiber bend loss. As to the BRD method, it has an outstanding self-adjusting capability and it can also avoid an excess phase difference caused by current-to-voltage converting circuit, thus this method has a high sensitivity. Furthermore, a so called dual-peak method based on the differential value of two adjacent absorption lines is introduced, the differential value proved has a linear relation with water vapor concentration, and this method provides a way to measure the concentration at high pressure. In addition, the influence of water vapor inside the optical components has been discussed.

  7. Measurement of gas/water uptake coefficients for trace gases active in the marine environment

    SciTech Connect

    Davidovits, P. (Boston Coll., Chestnut Hill, MA (United States). Dept. of Chemistry); Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. (Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics)

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean's surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry's law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  8. 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.

  9. 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

  10. Application of Photothermal Techniques in the Determination of the Water-Vapor Diffusion Coefficient and Thermal Effusivity of Hydrogels

    NASA Astrophysics Data System (ADS)

    Raymundo-Ortiz, A. I.; Ramos-Ramirez, E. G.; Cruz-Orea, A.; Salazar-Montoya, J. A.

    2013-09-01

    The main objective of this work is to determine the effect of different sodium alginate concentrations in hydrogels on their water-vapor diffusion coefficient (WVDC) and thermal effusivity (. These physical parameters were measured by photoacoustic and pyroelectric techniques, respectively. The results indicate that the higher values for the WVDC are presented at a concentration of 2 % sodium alginate. At lower concentrations of sodium alginate, the sample thermal effusivity increases, with a value close to the water thermal effusivity.

  11. Methods to improve the operating coefficient of performance of heat pump water heaters. [Add-on type

    Microsoft Academic Search

    D. M. Stipanuk; D. C. Ludington

    1983-01-01

    There are many factors which impact on the operational coefficient of performance of HPWHs. The Energy Factor values derived from the NBS\\/GAMA tests are not necessarily indicative of field performance. There are additional factors which impact on performance that need to be addressed. Two of these factors are discussed; temperature of inlet water to the heat exchanger (condensers) of heat

  12. Evaluation of a Simple HPLC Correlation Method for the Estimation of the Octanol-Water Partition Coefficients of Organic Compounds

    Microsoft Academic Search

    Jerome E. Haky; A. Michael Young

    1984-01-01

    A simple reverse-phase high performance liquid chromatographic method is evaluated for the estimation of octanol-water partition coefficients (log P) of organic compounds by correlation with their chromatographic capacity factors (k?). Using an unmodified commercial octadecylsilane column and a mobile phase consisting of methanol and an aqueous buffer, a linear relationship is established between the literature log P values of 68

  13. Diffusion coefficients of humic substances in agarose gel and in water.

    PubMed

    Lead, J R; Starchev, K; Wilkinson, K J

    2003-02-01

    Measurements of the diffusion coefficients of five different humic substances (HS) have been performed in water and in agarose hydrogels at several pH values (in the range of 3-10) and gel concentrations (in the range of 0.7-3% w/w). Fluorescence correlation spectroscopy (FCS) and classical diffusion cells were used in parallel to probe diffusion over both microscopic and mesoscopic distance scales. In general, agreement between the techniques was reasonable, which indicated that local nonhomogenities in the gel did not play an important role. Diffusion coefficients (D) in the gel were generally in the range of 0.9-2.5 x 10(-10) m2 s(-1) but were generally only 10-20% lower than in solution. At low pH values, one of the studied humic substances (a peat humic acid, PPHA) formed large aggregates that could not penetrate into the gel and therefore could not be defined by a single D value. The observed decreases of D in the gel for other HS were too large to be explained by the tortuousity and obstructive effects of the gel alone. D decreased slightly with increasing gel concentration and increased slightly with pH. Because modifications of D due to pH were similar in both the gel and the free solution, it is unlikely that complexation with the gel was greatly influenced by the pH. Rather, the main effect that appeared to decrease the diffusive flux in gels was likely small increases in the hydrodynamic radii of the humic macromolecules. An anomalous diffusion model was used to describe the FCS data in the gel. The characteristic exponent determined by fitting the autocorrelation functions with this model decreased only slightly (from 0.96 to 0.90) with increasing gel concentration providing support that HS complexation with the gel fibers was not very important. The results have important implications for our understanding of the fate and behavior of the HS and their associated pollutants and for interpreting metal speciation data obtained using gel-covered analytical sensors. PMID:12630462

  14. Estimation of amorphous organic carbon\\/water partition coefficients, subcooled aqueous solubilities, and n-octanol\\/water distribution coefficients of alkylbenzenes and polycyclic aromatic hydrocarbons

    Microsoft Academic Search

    Paul C. M. van Noort

    2009-01-01

    The aim of this work was to derive a relation between the number of specific carbon atoms in alkylbenzenes and PAHs and the average logKoc 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

  15. [Determination of trace cobalt in water samples by graphite furnace atomic absorption spectrometry after cloud point].

    PubMed

    Zhang, Yuan; Luo, Wen-hong; Li, Hui

    2005-04-01

    In buffer solution of citric acid monohydrate-disodium hydrogen phosphate at pH 5-7.5, cobalt water samples were chelated by 1-(2-pyridylazo)-2-naphthol (PAN) to form Co-PAN. After water-bath at 66 degrees C for two hours, Co-PAN is extracted into Triton X-100 nonionic surfactant phase and separated from bulk water. Extracted cobalt content was measured by graphite furnace atomic absorption spectrometry. The surfactant phase separated was treated with 0.5% HNO3-0.1% Pd(NO3)2 to remove background interference at 1200 degrees C temperature. The pre-concentration of cobalt in water samples permitted the detection of 0.003 microg x L(-1) (10sigma) with the enhancement factor of 100. The recoveries were 90.5%-106%. The proposed method was applied to the determination of cobalt in water samples and satisfactory results were obtained. PMID:16097690

  16. 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

  17. Explicit use of the Biot coefficient in predicting shear-wave velocity of water-saturated sediments

    USGS Publications Warehouse

    Lee, M.W.

    2006-01-01

    Predicting the shear-wave (S-wave) velocity is important in seismic modelling, amplitude analysis with offset, and other exploration and engineering applications. Under the low-frequency approximation, the classical Biot-Gassmann theory relates the Biot coefficient to the bulk modulus of water-saturated sediments. If the Biot coefficient under in situ conditions can be estimated, the shear modulus or the S-wave velocity can be calculated. The Biot coefficient derived from the compressional-wave (P-wave) velocity of water-saturated sediments often differs from and is less than that estimated from the S-wave velocity, owing to the interactions between the pore fluid and the grain contacts. By correcting the Biot coefficients derived from P-wave velocities of water-saturated sediments measured at various differential pressures, an accurate method of predicting S-wave velocities is proposed. Numerical results indicate that the predicted S-wave velocities for consolidated and unconsolidated sediments agreewell with measured velocities. ?? 2006 European Association of Geoscientists & Engineers.

  18. Effect of aspirin on intestinal absorption of glucose, sodium, and water in man

    Microsoft Academic Search

    C Arvanitakis; G H Chen; J Folscroft; N J Greenberger

    1977-01-01

    The effect of aspirin on small intestinal function in six healthy volunteers was examined using a segmental perfusion technique, with a test solution of 40 mM D-glucose, 140 mM NaCl, and 0-5% polyethylene glycol. Jejunal glucose, sodium, and water absorption rates were inhibited by 50% after oral administration of 2-6 g aspirin. Adenosine triphosphate (ATP) concentration was assayed in jejunal

  19. Performance Evaluation of a 4.5 kW (1.3 Refrigeration Tons) Air-Cooled Lithium Bromide/Water Solar Powered (Hot-Water-Fired) Absorption Unit

    SciTech Connect

    Zaltash, Abdolreza [ORNL; Petrov, Andrei Y [ORNL; Linkous, Randall Lee [ORNL; Vineyard, Edward Allan [ORNL

    2007-01-01

    During the summer months, air-conditioning (cooling) is the single largest use of electricity in both residential and commercial buildings with the major impact on peak electric demand. Improved air-conditioning technology has by far the greatest potential impact on the electric industry compared to any other technology that uses electricity. Thermally activated absorption air-conditioning (absorption chillers) can provide overall peak load reduction and electric grid relief for summer peak demand. This innovative absorption technology is based on integrated rotating heat exchangers to enhance heat and mass transfer resulting in a potential reduction of size, cost, and weight of the "next generation" absorption units. Rotartica Absorption Chiller (RAC) is a 4.5 kW (1.3 refrigeration tons or RT) air-cooled lithium bromide (LiBr)/water unit powered by hot water generated using the solar energy and/or waste heat. Typically LiBr/water absorption chillers are water-cooled units which use a cooling tower to reject heat. Cooling towers require a large amount of space, increase start-up and maintenance costs. However, RAC is an air-cooled absorption chiller (no cooling tower). The purpose of this evaluation is to verify RAC performance by comparing the Coefficient of Performance (COP or ratio of cooling capacity to energy input) and the cooling capacity results with those of the manufacturer. The performance of the RAC was tested at Oak Ridge National Laboratory (ORNL) in a controlled environment at various hot and chilled water flow rates, air handler flow rates, and ambient temperatures. Temperature probes, mass flow meters, rotational speed measuring device, pressure transducers, and a web camera mounted inside the unit were used to monitor the RAC via a web control-based data acquisition system using Automated Logic Controller (ALC). Results showed a COP and cooling capacity of approximately 0.58 and 3.7 kW respectively at 35 C (95 F) design condition for ambient temperature with 40 C (104 F) cooling water temperature. This is in close agreement with the manufacturer data of 0.60 for COP and 3.9 kW for cooling capacity. This study resulted in a complete performance map of RAC which will be used to evaluate the potential benefits of rotating heat exchangers in making the "next-generation" absorption chillers more compact and cost effective without any significant degradation in the performance. In addition, the feasibility of using rotating heat exchangers in other applications will be evaluated.

  20. Investigation of the impact of water absorption on retinal OCT imaging in the 1060 nm range.

    PubMed

    Marschall, Sebastian; Pedersen, Christian; Andersen, Peter E

    2012-07-01

    Recently, the wavelength range around 1060 nm has become attractive for retinal imaging with optical coherence tomography (OCT), promising deep penetration into the retina and the choroid. The adjacent water absorption bands limit the useful bandwidth of broadband light sources, but until now, the actual limitation has not been quantified in detail. We have numerically investigated the impact of water absorption on the axial resolution and signal amplitude for a wide range of light source bandwidths and center wavelengths. Furthermore, we have calculated the sensitivity penalty for maintaining the optimal resolution by spectral shaping. As our results show, with currently available semiconductor-based light sources with up to 100-120 nm bandwidth centered close to 1060 nm, the resolution degradation caused by the water absorption spectrum is smaller than 10%, and it can be compensated by spectral shaping with negligible sensitivity penalty. With increasing bandwidth, the resolution degradation and signal attenuation become stronger, and the optimal operating point shifts towards shorter wavelengths. These relationships are important to take into account for the development of new broadband light sources for OCT. PMID:22808433

  1. 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.-

  2. Water vapor absorption spectra of the upper atmosphere (45-185 cm(-1)).

    PubMed

    Augason, G C; Mord, A J; Witteborn, F C; Erickson, E F; Swift, C D; Caroff, L J; Kunz, L W

    1975-09-01

    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 +/- 0.4 mum of percipitable water on 30 August 1971 and 2.4 +/- 0.3 mum of precipitable water on 6 January 1972. PMID:20154976

  3. Determining beryllium in drinking water by graphite furnace atomic absorption spectroscopy

    SciTech Connect

    Lytle, D.A.; Schock, M.R.; Dues, N.R.; Doerger, J.U.

    1993-01-01

    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 successfully eliminated common chemical interferences in drinking water samples analyzed for beryllium content, as well as interferences encountered during jar testing of beryllium removal by alum coagulation. The method proved to be a simple, accurate, and precise alternative to the method of standard additions. Method detection limit was 0.09 microgram/l, with a linear calibration range of 0 to 6 microgram/l.

  4. Aging of Toughened Polylactic Acid Nanocomposites: Water Absorption, Hygrothermal Degradation and Soil Burial Analysis

    Microsoft Academic Search

    Harintharavimal Balakrishnan; Azman Hassan; Muhammad Imran; Mat Uzir Wahit

    The environmental aging behaviour of montmorillonite (MMT) filled polylactic acid (PLA) nanocomposites (PLA\\/MMT) and linear\\u000a low density polyethylene (LLDPE)-toughened PLA (PLA\\/LLDPE ratio = 90\\/10) nanocomposites (PLA\\/LLDPE\\/MMT) were investigated\\u000a in this study. The nanocomposites were subjected to water absorption, hygrothermal degradation and soil burial analysis. Both\\u000a PLA\\/MMT and PLA\\/LLDPE\\/MMT nanocomposites were immersed in distilled water at three different temperatures (room temperature,\\u000a 60, and

  5. The phase behavior and absorption spectra of the ternary system cobaltous chloride-water-acetonitrile 

    E-print Network

    Bobbitt, Jeffrey Lovett

    1967-01-01

    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... FIGURE F IGUP~& 4 FIGURZ 5 Zxpansion. of Phase Diagram in Region of High Acetonitrile Concentration . . 22 Expansion of Phase Diagram in Region of High Water Concentration Retangular Diagram of Ternary System Based on Cobaltous Chloride and Water...

  6. Local structures of methanol-water binary solutions studied by soft X-ray absorption spectroscopy.

    PubMed

    Nagasaka, Masanari; Mochizuki, Kenji; Leloup, Valentin; Kosugi, Nobuhiro

    2014-04-24

    Liquid methanol shows one- and two-dimensional (1D/2D) hydrogen bond (HB) networks, and liquid water shows three-dimensional (3D) HB networks. We have clearly found three different local structures around the methyl group of methanol-water binary solutions (CH3OH)X(H2O)1-X at different concentrations in C K-edge soft X-ray absorption spectroscopy (XAS). With the help of molecular dynamics simulations, we have discussed the concentration dependence of the hydrophobic interaction at the methyl group in the C K-edge XAS spectra. In the methanol-rich region I (1.0 > X > 0.7), a small amount of water molecules exists separately around dominant 1D/2D HB networks of methanol clusters. In the region II (0.7 > X > 0.3), the hydrophobic interaction of the methyl group is dominant due to the increase of mixed methanol-water 3D network structures. In the water-rich region III (0.3 > X > 0.05), methanol molecules are separately embedded in dominant 3D HB networks of water. On the other hand, the pre-edge feature in the O K-edge XAS shows almost linear concentration dependence. It means the HB interaction between methanol and water is almost the same as that of water-water and of methanol-methanol. PMID:24694018

  7. 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.

  8. 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

  9. A Determination of the Condensation Coefficient of Water from the Growth Rate of Small Cloud Droplets

    Microsoft Academic Search

    N. Chodes; J. Warner; A. Gagin

    1974-01-01

    An experiment is described, in which the rate of growth of cloud droplets, in a thermal diffusion chamber, is measured accurately to yield the value of the condensation coefficient. The data obtained from measurements of 40 individual droplets grown at four different supersaturations (0.40,0.49,0.62 and 0.72%) suggests that the values of the condensation coefficient are 0.037, 0.033, 0.031 and 0.033,

  10. Henry's Law Coefficient (Solubility) of Toluene in Water with GC-FID A laboratory experiment for junior level undergraduate Analytical Chemistry Lab course

    E-print Network

    Lee, Shan-Hu

    , R., Henrys Law constants (solubilities), http://www.mpch- mainz.mpg.de/~sander/res/henry.html#21 Henry's Law Coefficient (Solubility) of Toluene in Water with GC-FID A laboratory experiment is to measure Henrys Law coefficient (that is, solubility) of toluene in water with a gas chromatography (GC

  11. Enhancement of intestinal water absorption and sodium transport by glycerol in rats.

    PubMed

    Wapnir, R A; Sia, M C; Fisher, S E

    1996-12-01

    Glycerol (Gly) is a hydrophilic, absorbable, and energy-rich solute that could make water absorption more efficient. We investigated the use of Gly in a high-energy beverage containing corn syrup (CS) by using a small intestine perfusion procedure in the rat, an approach shown earlier to provide good preclinical information. The effectiveness of several formulations with Gly and CS was compared with commercial products and to experimental formulas where Gly substituted for glucose (Glc). The CS-Gly combination was more effective than preparations on the market containing sucrose and Glc-fructose syrups (G-P and G-L, respectively) in maintaining a net water absorption balance in the test jejunal segment [CS-Gly = 0.21 +/- 0.226, G-L = -1.516 +/- 0.467, and G-P = -0.299 +/- 0.106 (SE) microliter.min-1.cm-1 (P = 0.0113)] and in reducing sodium release into the lumen [CS-Gly = -133.2 +/- 16.2, G-L = -226.7 +/- 25.2, and G-P = -245.6 +/- 23.4 nmol.min-1.cm-1 (P = 0.0022)]. In other preparations, at equal CS concentrations (60 and 80 g/l, respectively), Gly clearly improved net water absorption over a comparable Glc-containing product [CS60-Gly = 0.422 +/- 0.136 and CS80-Gly = 0.666 +/- 0.378 vs. CS60-Glc = -0.282 +/- 0.200 and CS80-Glc = -1.046 +/- 0.480 microliters.min-1.cm-1 (P = 0.0019)]. On the basis of the data of this rat intestine perfusion model, Gly could be a useful ingredient in energy-rich beverages and might enhance fluid absorption in humans. PMID:9018501

  12. Application of noise analysis technique for monitoring the moderator temperature coefficient of reactivity in pressurized water reactors

    Microsoft Academic Search

    D. J. Shieh; B. R. Upadhyaya; F. J. Sweeney

    1987-01-01

    A new technique, based on the noise analysis of neutron detector and core-exit coolant temperature signals, is developed for monitoring the moderator temperature coefficient of reactivity in pressurized water reactors (PWRs). A detailed multinodal model is developed and evaluated for the reactor core subsystem of the loss-of-fluid test (LOFT) reactor. This model is used to study the effect of changing

  13. Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate

    Microsoft Academic Search

    Urszula Doma?ska; Marta Królikowska; William E. Acree; Gary A. Baker

    2011-01-01

    The activity coefficients at infinite dilution, ?13?, for 36 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, ethers, acetone, and water, in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate, [EMIM][TCB], were determined by gas–liquid chromatography at temperatures from 298.15K to 358.15K. These values are compared to those previously published for selected solutes in the same ionic liquid. The values

  14. 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,

  15. Precise Determination of Hydrostatic Pressure Correction Coefficient of Triple Point Cell of Water using Cryogenic Current Comparator Bridge

    Microsoft Academic Search

    Masakazu Nakanishi; Hirohisa Sakurai

    2005-01-01

    Applying a cryogenic current comparator bridge to resistance thermometry, the temperature distributions along the thermometer wells of two triple point cells of water are precisely measured using a standard platinum resistance thermometer with low measuring currents of about 0.1 mA. The average hydrostatic pressure coefficient of the two cells calculated from the temperature distributions is -0.854(38) mK\\/m. This value agrees

  16. Estimating temperature dependence of solubility and octanol–water partition coefficient for organic compounds using RP-HPLC

    Microsoft Academic Search

    Antonio Finizio; Antonio Di Guardo

    2001-01-01

    Temperature dependence data for physical–chemical properties is increasingly required for modelling the fate of chemicals in the environment. Solubility and octanol–water partition coefficient (Kow) are among the most important parameters. A simple and fast method is presented to determine solubility and Kow of organic chemicals at different temperatures (5°C, 15°C, 25°C, 35°C) utilising a variable temperature RP-HPLC column. Correlations between

  17. OCTAN-1-OL/WATER PARTITION COEFFICIENTS OF P-BENZO- AND P-NAPHTHOQUINONES CORRECTED FOR PH EFFECT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of pH of the aqueous phase on the octan-1-ol / water partition coefficients (kow) of quinones was demontrated. The kow of a series of p-benzo- and p-naphthoquinones were determined using a mildly buffered aqueous phase (1 mM Hepes, pH 7.0) to correct for the pH effects on the lipophilicit...

  18. 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.

  19. 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

  20. Correlation of the octanol/water partition coefficient with clearance half-times of intratracheally instilled aromatic hydrocarbons in rats.

    PubMed

    Bond, J A; Baker, S M; Bechtold, W E

    1985-09-01

    Studies on the lung retention of polycyclic aromatic hydrocarbons (PAH) after inhalation have indicated that, in general, the PAH are rapidly cleared from the respiratory tract. Clearance of the PAH from the lungs is best described as bi-phasic, with the long-term component of the clearance curve having a half-time of greater than 24 h. The purpose of this study was to determine whether a relationship exists between the lipophilicity (as measured by the octanol/water partition coefficient, P) of various PAH and the short-term and long-term clearance half-times of PAH in rat lungs. Female F344/Crl rats were administered intratracheally 1 nmol of 14C-labelled anthracene (AN), benz[a]anthracene (BA), 1-nitropyrene (NP), 6-nitrobenzo[a]pyrene (6-NBP), or dibenzo[c,g]carbazole (DBC). At various times after instillation rats were sacrificed and the amount of 14C remaining in the lungs was determined. Octanol/water partition coefficients were experimentally determined for each of the PAH used. Clearance of 14C from rat lungs following instillation of the different PAH was biphasic. In all cases, greater than 85% of the initial dose instilled was cleared with a half-time of less than 1 h. The half-times for clearance of the residual 14C (1-15% of the dose) were 26, 30, 36, 53 and 63 h for AN, NP, 6-NBP, BA and DBC, respectively. The log of the octanol/water partition coefficients for the different PAH examined ranged from 4.1 (AN) to 6.05 (DBC). Plots of the octanol/water coefficients vs. the long-term clearance half-time for the PAH indicated a linear correlation (p less than 0.001; r2 = 0.96). The results from this study indicate that the greater the lipophilicity of the PAH, the slower the long-term clearance of a small fraction (1-15%) of PAH from rat lungs. These data suggest that predictions of long-term lung clearance can be made for PAH with log octanol/water partition coefficients between 4 and 6. PMID:4049435

  1. 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

  2. Thermal design of lithium bromide-water solution vapor absorption cooling system for indirect evaporative cooling for IT pod

    NASA Astrophysics Data System (ADS)

    Sawant, Digvijay Ramkrishna

    Nowadays with increase use of internet, mobile there is increase in heat which ultimately increases the efficient cooling system of server room or IT POD. Use of traditional ways of cooling system has ultimately increased CO2 emission and depletion of CFC's are serious environmental issues which led scientific people to improve cooling techniques and eliminate use of CFC's. To reduce dependency on fossil fuels and 4environmental friendly system needed to be design. For being utilizing low grade energy source such as solar collector and reducing dependency on fossil fuel vapour absorption cooling system has shown a great driving force in today's refrigeration systems. This LiBr-water aabsorption cooling consists of five heat exchanger namely: Evaporator, Absorber, Solution Heat Exchanger, Generator, Condenser. The thermal design was done for a load of 23 kW and the procedure was described in the thesis. There are 120 servers in the IT POD emitting 196 W of heat each on full load and some of the heat was generated by the computer placed inside the IT POD. A detailed procedure has been discussed. A excel spreadsheet was to prepared with varying tube sizes to see the effect on flows and ultimately overall heat transfer coefficient.

  3. Laboratory measurements of water vapour continuum absorption in spectral region 5000-5600 cm-1: Evidence for water dimers

    NASA Astrophysics Data System (ADS)

    Ptashnik, Igor V.; Smith, Kevin M.; Shine, Keith P.; Newnham, David A.

    2004-10-01

    In spite of decades of extensive studies, the role of water dimers (WD) in the atmospheric radiation budget is still controversial. In order to search for evidence of the dimer in the solar near infrared, high spectral resolution pure water vapour absorption spectra were obtained in laboratory conditions for two different pressures and temperatures in the spectral region 5000-5600 cm-1 (1.785 to 2 m). The residual was derived as a difference between the measured optical depth and the calculated one for water monomer, using the modified HITRAN database and two different representations of the water vapour continuum: CKD-2.4 (Clough-Kneizys-Davies) and the Ma and Tipping continuum. In both cases the residuals obtained are very similar to those expected from a recent theoretical calculation of the WD absorption. However, the WD band half-width at half maximum (HWHM) and dimerization equilibrium constant, Keq, required to provide a best fit to the residual, differ for each case. To be in best agreement with the residual calculated by using the Ma and Tipping continuum, the WD bands HWHM should be ~28 cm-1, and Keq = 0.02 ± 0.0035 atm-1 and 0.043 ± 0.0055 atm-1 for temperatures 342 and 299 K respectively. For the residual calculated using the CKD-2.4 continuum the fitted value of the HWHM is ~18 cm-1, and Keq = 0.011 ± 0.0025 atm-1 (342 K) and 0.018 ± 0.003 atm-1 (299 K). It is concluded that a substantial part of the WD absorption is already implicitly included within the CKD-2.4 continuum model. The increase in estimated clear-sky global mean absorption of solar radiation due to WD varies from 0.5% to 2.0%, depending on the set of WD parameters used. On the basis of a comparison of the derived Keq values with others in the literature, the higher estimate is favoured.

  4. 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

  5. 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

  6. A new device for acquiring ground truth on the absorption of light by turbid waters

    NASA Technical Reports Server (NTRS)

    Klemas, V. (principal investigator); Srna, R.; Treasure, W.

    1974-01-01

    The author has identified the following significant results. A new device, called a Spectral Attenuation Board, has been designed and tested, which enables ERTS-1 sea truth collection teams to monitor the attenuation depths of three colors continuously, as the board is being towed behind a boat. The device consists of a 1.2 x 1.2 meter flat board held below the surface of the water at a fixed angle to the surface of the water. A camera mounted above the water takes photographs of the board. The resulting film image is analyzed by a micro-densitometer trace along the descending portion of the board. This yields information on the rate of attenuation of light penetrating the water column and the Secchi depth. Red and green stripes were painted on the white board to approximate band 4 and band 5 of the ERTS MSS so that information on the rate of light absorption by the water column of light in these regions of the visible spectrum could be concurrently measured. It was found that information from a red, green, and white stripe may serve to fingerprint the composition of the water mass. A number of these devices, when automated, could also be distributed over a large region to provide a cheap method of obtaining valuable satellite ground truth data at present time intervals.

  7. 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.

  8. 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.

  9. Efficient random walk particle tracking algorithm for advective-dispersive transport in media with discontinuous dispersion coefficients and water contents

    NASA Astrophysics Data System (ADS)

    Bechtold, M.; Vanderborght, J.; Ippisch, O.; Vereecken, H.

    2011-10-01

    Random walk particle tracking (RWPT) is a well established and efficient alternative to grid-based Eulerian approaches when simulating the advection-dispersion transport problem in highly heterogeneous porous media. However, RWPT methods suffer from a lack of accuracy when the dispersion tensor or the water content is spatially discontinuous. We present improvements to the concept of a partially reflecting barrier used to account for these discontinuities: (1) the nonlinear time splitting with ? that corrects for the systematic overestimation of the second dispersion displacement across an element interface when linear time splitting is used; (2) the one-sided reflection coefficient that correctly represents the effect of discontinuous dispersion coefficients and water content but eliminates redundant reflections of the two-sided reflection coefficient and limits the error for discrete ?; and (3) the transformation of the dispersive displacement across the element interface for complex multidimensional transport problems. The proposed improvements are verified numerically by comparison with an analytical solution and a reference RWPT method. The results indicate an increased efficiency and accuracy of the new RWPT algorithm. Because the new algorithm efficiently simulates both advection- and dispersion-dominated transport conditions, it enhances the applicability of RWPT to scenarios in which both conditions occur, as, for example, in the highly transient unsaturated zone. The algorithm is easily implemented and it is shown that the computational benefit increases with increasing variability of the hydraulic parameter field.

  10. Intracavity Dye-Laser Absorption Spectroscopy (IDLAS) for application to planetary molecules

    NASA Technical Reports Server (NTRS)

    Lang, Todd M.; Allen, John E., Jr.

    1990-01-01

    Time-resolved, quasi-continuous wave, intracavity dye-laser absorption spectroscopy is applied to the investigation of absolute absorption coefficients for vibrational-rotational overtone bands of water at visible wavelengths. Emphasis is placed on critical factors affecting detection sensitivity and data analysis. Typical generation-time dependent absorption spectra are given.

  11. 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

  12. Neutron scattering study on dynamics of water molecules in MCM-41. 2. Determination of translational diffusion coefficient.

    PubMed

    Takahara, Shuichi; Sumiyama, Naoya; Kittaka, Shigeharu; Yamaguchi, Toshio; Bellissent-Funel, Marie-Claire

    2005-06-01

    Quasielastic neutron scattering (QENS) spectra of water-filled MCM-41 samples (pore diameters: 21.4 and 28.4 Angstrom) were measured over the temperature range 238-298 K and the momentum transfer range 0.31-0.99 A(-1) to investigate the dynamics of confined water molecules. The spectra, which consist mainly of contributions from the translational diffusion of water molecules, were analyzed by using the Lorentzian and the stretched exponential functions. Comparison of the fits indicated that the latter analysis is more reliable than the former one. The fraction of immobile water molecules located in the vicinity of the pore walls, which give an elastic component, was found to be 0.044-0.061 in both pores. The stretch exponent beta was determined as 0.66-0.80. It was shown that the translational diffusion of water molecules in the pores is decelerated by confinement and that the deceleration becomes marked with a decrease in pore size. The ratios of the translational diffusion coefficient D(T) of confined water to that of bulk water at room temperature were within a range of 0.47-0.63. PMID:16852371

  13. 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.

  14. Drag Coefficient of Water Droplets Approaching the Leading Edge of an Airfoil

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida Garcia

    2013-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. An airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Results are presented and discussed for drag coefficients of droplets with diameters in the range of 300 to 1800 micrometers, and airfoil velocities of 50, 70 and 90 meters/second. The effect of droplet oscillation on the drag coefficient is discussed.

  15. Turbulence at the Air-Water Interface in Lakes of Different Sizes: Consequences for Gas Transfer Coefficients

    NASA Astrophysics Data System (ADS)

    MacIntyre, S.; Crowe, A. T.; Amaral, J. H.; Arneborg, L.; Bastviken, D.; Forsberg, B. R.; Melack, J. M.; Tota, J.; Tedford, E. W.; Karlsson, J.; Podgrajsek, E.; Andersson, A.; Rutgersson, A.

    2014-12-01

    Similarity scaling predicts that wind induced shear will be the dominant source of turbulence near the air-water interface in lakes with low to moderate wind forcing. Turbulence is expected to be enhanced with wave activity; results are conflicting on the effects of heating and cooling. We measured turbulence with an acoustic Doppler velocimeter (ADV) and / or a temperature-gradient microstructure profiler and obtained correlative time series measurements of meteorology and water column temperature in a 800 m2 arctic pond, a 1 ha boreal lake, and a large tropical reservoir. Turbulence measurements with both instruments corroborated those calculated from similarity scaling in the boreal lake. Within the arctic pond, dissipation rates obtained with the ADV were in agreement with those from similarity scaling when winds exceeded ~1.5 m/s with a greater frequency of measurable dissipation rates when surface waves were present. Dissipation rates in the tropical reservoir reached and often exceeded 10?6 m2 s-3 in the upper meter under light winds and decreased by an order of magnitude with cooling or rainfall. Under cooling, dissipation rates were at least an order of magnitude higher in the uppermost 25 cm bin than in the water column below. Gas transfer coefficients calculated from concurrent measurements of greenhouse gas fluxes with floating chambers and the surface renewal model using the estimates of turbulence were in agreement. These results support the predictions of Monin-Obuhov similarity scaling in that shear dominates turbulence production near the air-water interface under heating and cooling, illustrate spatial variability in turbulence production in small water bodies due to the intermittency of wind interacting with the water's surface, are in agreement with prior oceanic observations that shear and associated turbulence can be intensified in shallow mixing layers under heating with light winds, and illustrate the utility of similarity scaling for predicting gas transfer coefficients.

  16. 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.

  17. 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.

  18. X-Ray Absorption Signatures of the Molecular Environment in Water and Ice

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Wu, Xifan; Car, Roberto

    2010-07-01

    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 effects of temperature change in the liquid, are reproduced from 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 nonbonded 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.

  19. Atmospheric pre-corrected differential absorption techniques to retrieve columnar water vapor: Theory and simulations

    SciTech Connect

    Borel, C.C.; Schlaepfer, D.

    1996-03-01

    Two different approaches exist to retrieve columnar water vapor from imaging spectrometer data: (1) Differential absorption techniques based on: (a) Narrow-Wide (N/W) ratio between overlapping spectrally wide and narrow channels (b) Continuum Interpolated Band Ratio (CIBR) between a measurement channel and the weighted sum of two reference channels; and (2) Non-linear fitting techniques which are based on spectral radiative transfer calculations. The advantage of the first approach is computational speed and of the second, improved retrieval accuracy. Our goal was to improve the accuracy of the first technique using physics based on radiative transfer. Using a modified version of the Duntley equation, we derived an {open_quote}Atmospheric Pre-corrected Differential Absorption{close_quote} (APDA) technique and described an iterative scheme to retrieve water vapor on a pixel-by-pixel basis. Next we compared both, the CIBR and the APDA using the Duntley equation for MODTRAN3 computed irradiances, transmissions and path radiance (using the DISORT option). This simulation showed that the CIBR is very sensitive to reflectance effects and that the APDA performs much better. An extensive data set was created with the radiative transfer code 6S over 379 different ground reflectance spectra. The calculated relative water vapor error was reduced significantly for the APDA. The APDA technique had about 8% (vs. over 35% for the CIBR) of the 379 spectra with a relative water vapor error of greater than {+-}5%. The APDA has been applied to 1991 and 1995 AVIRIS scenes which visually demonstrate the improvement over the CIBR technique.

  20. Atmospheric water vapor estimate by a differential absorption technique with the polarisation and directionality of the Earth reflectances (POLDER) instrument

    Microsoft Academic Search

    S. Bouffiès; F. M. Bréon; D. Tanré; P. Dubuisson

    1997-01-01

    The polarization and directionality of the Earth reflectances (POLDER) instrument, to be launched in 1996 on the Japanese ADEOS (advanced Earth observing satellite) platform includes a channel which covers the 910 nm water vapor absorption band (near IR), as well as a channel centered at 865 nm. An estimate of the total atmospheric water vapor content can be derived from

  1. Sublimation coefficient of water ice under simulated cometary-like conditions

    NASA Astrophysics Data System (ADS)

    Kossacki, Konrad J.; Markiewicz, Wojciech J.; Skorov, Yuri; Kömle, Norbert. I.

    1999-12-01

    In papers dealing with evolution of cometary nuclei it is commonly assumed that the coefficients of sublimation ?s and condensation ?c of vapour are both equal to one. The experimental investigation of ice samples under simulated cometary-like conditions (Kossacki, K.J., Kömle, N.I., Leliwa-Kopysty?ski, J., Kargl, G., 1997. Thermal and structural evolution of cometary subsurface layer: selfconsistent model and experimental verification. Icarus 128, 127-144) suggests, however, that the sublimation flux calculated with the Hertz-Knudsen formula and the above assumption is nearly an order of magnitude too high. This may imply that actual values of ?s for the ice/dust sample used in these experiments are of the order of 0.1. A similar conclusion can be drawn for ?c from the results of various experiments concerning growth of ice crystals from the vapour phase and their sublimation (Lamb, D., Scott, W.D., 1972. Linear growth rates of ice crystals grown from the vapor phase. Journal of Crystal Growth 12, 21-31; Beckmann, W., Lacmann, R., 1982. Interface kinetics of growth and evaporation of ice II. Journal of Crystal Growth 58, 433-442; Sei, T., Gonda, T., 1989. The growth mechanism and the habit change of ice crystals growing from the vapour phase. Journal of Crystal Growth 94, 697-707). The exact values of both of these coefficients depend on various parameters such as temperature, concentration of surface impurities and deviation of the vapour pressure from that of the phase equilibrium. In this work the temperature dependence of the sublimation and condensation coefficients is discussed and an appropriate formula is proposed to fit the experimental results. This new formulation is then used to analyse the implications for the thermal conductivity of a porous cometary-like ice and the rate of vapour flux from a cometary nucleus.

  2. Seasonal variability in the vertical attenuation coefficient at 490 nm (K490) in waters around Puerto Rico and US Virgin Islands.

    E-print Network

    Gilbes, Fernando

    Virgin Islands, MODIS Aqua, ENVI #12;INTRODUCTION The vertical diffuse attenuation coefficient (Kd properties. The vertical diffuse attenuation coefficient (Kd) was evaluated for the waters around Puerto Rico and the US Virgin Islands. The MODIS K490 of Band 3 Level-2 daily images were processed with a resolution

  3. 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

  4. A Fast and reliable spectroscopic method for the determination of membrane-water partition coefficients of organic compounds

    Microsoft Academic Search

    Baltazar de Castro; Paula Gameiro; José L. F. C. Lima; Carla Matos; Salette Reis

    2001-01-01

    Partition coefficients (K\\u000a \\u000a p\\u000a ) between egg yolk phosphatidylcholine multilamellar vesicles and water were determined for two nonsteroidal anti-inflammatory\\u000a drugs (indomethacin and acemetacin) using two independent methodologies: derivative spectrophotometry and variation of the\\u000a experimental acidity constant in the presence of increasing vesicle concentration. Second-derivative spectrophotometry allowed\\u000a for total elimination of background signal effects arising from lipid vesicles, without the need

  5. Microwave-assisted synthesis of water-soluble, fluorescent gold nanoclusters capped with small organic molecules and a revealing fluorescence and X-ray absorption study.

    PubMed

    Helmbrecht, C; Lützenkirchen-Hecht, D; Frank, W

    2015-03-21

    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. PMID:25692478

  6. 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.

  7. Polarizable interaction potential for water from coupled cluster calculations. II. Applications to dimer spectra, virial coefficients, and simulations of liquid water.

    PubMed

    Bukowski, Robert; Szalewicz, Krzysztof; Groenenboom, Gerrit C; van der Avoird, Ad

    2008-03-01

    The six-dimensional CC-pol interaction potential for the water dimer was used to predict properties of the dimer and of liquid water, in the latter case after being supplemented by a nonadditive potential. All the results were obtained purely from first principles, i.e., without any fitting to experimental data. Calculations of the vibration-rotation-tunneling levels of (H(2)O)(2) and (D(2)O)(2), a very sensitive test of the potential surface, gave results in good agreement with experimental high-resolution spectra. Also the virial coefficients and properties of liquid water agree well with measured values. The present model performs better than published force fields for water in a simultaneous reproduction of experimental data for dimer spectra, virials, and properties of the liquid. PMID:18331100

  8. Polarizable interaction potential for water from coupled cluster calculations. II. Applications to dimer spectra, virial coefficients, and simulations of liquid water

    NASA Astrophysics Data System (ADS)

    Bukowski, Robert; Szalewicz, Krzysztof; Groenenboom, Gerrit C.; van der Avoird, Ad

    2008-03-01

    The six-dimensional CC-pol interaction potential for the water dimer was used to predict properties of the dimer and of liquid water, in the latter case after being supplemented by a nonadditive potential. All the results were obtained purely from first principles, i.e., without any fitting to experimental data. Calculations of the vibration-rotation-tunneling levels of (H2O)2 and (D2O)2, a very sensitive test of the potential surface, gave results in good agreement with experimental high-resolution spectra. Also the virial coefficients and properties of liquid water agree well with measured values. The present model performs better than published force fields for water in a simultaneous reproduction of experimental data for dimer spectra, virials, and properties of the liquid.

  9. Effect of water absorption on the thermal–mechanical properties of HTPB modified DGEBA-based epoxy systems

    Microsoft Academic Search

    N. G. Berry; J. R. M. d’Almeida; F. L. Barcia; B. G. Soares

    2007-01-01

    Three DGEBA-based epoxy systems modified by the incorporation of hydroxyl-terminated polybutadiene (HTPB) were aged by water immersion. These systems have different macromolecular structures, and comprise a monophasic system (EPI) and two biphasic systems (EPH and EPA) differing in the size of the elastomeric domains. The diffusion coefficient and the water saturation value were successfully determined using the Fickian diffusion model.

  10. 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...

  11. Intermolecular potential and second virial coefficient of the water-hydrogen complex

    Microsoft Academic Search

    Matthew P. Hodges; Richard J. Wheatley; Gregory K. Schenter; Allan H. Harvey

    2004-01-01

    We construct a rigid-body (five-dimensional) potential-energy surface for the water-hydrogen complex using scaled perturbation theory (SPT). An analytic fit of this surface is obtained, and, using this, two minima are found. The global minimum has C2v symmetry, with the hydrogen molecule acting as a proton donor to the oxygen atom on water. A local minimum with Cs symmetry has the

  12. Intermolecular potential and second virial coefficient of the water–hydrogen complex

    Microsoft Academic Search

    Matthew P. Hodges; Richard J. Wheatley; Gregory K. Schenter; Allan H. Harvey

    2004-01-01

    We construct a rigid-body (five-dimensional) potential-energy surface for the water–hydrogen complex using scaled perturbation theory (SPT). An analytic fit of this surface is obtained, and, using this, two minima are found. The global minimum has C2v symmetry, with the hydrogen molecule acting as a proton donor to the oxygen atom on water. A local minimum with Cs symmetry has the

  13. 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

  14. THz absorption spectra and stability of Fe water complexes calculated by density functional theory

    NASA Astrophysics Data System (ADS)

    Huang, L.; Lambrakos, S. G.; Shabaev, A.; Massa, L.; Yapijakis, C.

    2013-05-01

    Monitoring of water contaminants implies a need for determining their dielectric response properties with re- spect to electromagnetic wave excitation at various frequencies. Iron is a naturally occurring water contaminant resulting from decaying vegetation, which is at much higher concentrations than any other metal contaminant. The present study uses density functional theory (DFT) for the calculation of ground state resonance struc- ture and molecular stability analysis for Fe water complexes. The calculations presented are for excitation by electromagnetic waves at frequencies within the THz range. Dielectric response functions calculated by DFT can be used for the analysis of water contaminants. These functions provide quantitative initial estimates of spectral response features for subsequent adjustment with respect to additional information such as laboratory measurements and other types of theory based calculations. In addition, with respect to qualitative analysis, DFT calculated absorption spectra provide for molecular level interpretation of response structure. The DFT software GAUSSIAN was used for the calculations of ground state resonance structure presented here.

  15. THz Absorption Spectra of Fe and Mg Water Complexes Calculated by Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Huang, L.; Lambrakos, S. G.; Shabaev, A.; Massa, L.; Yapijakis, C.

    2013-05-01

    Monitoring of water contaminants implies a need for determining their dielectric response properties with respect to electromagnetic wave excitation at various frequencies. Iron is a naturally occurring water contaminant, which is the result of decaying vegetation and is at much higher concentrations than any other metal contaminant. The present study uses density functional theory (DFT) for the calculation of ground state resonance structure and stability analysis of Fe water complexes. The calculations presented are for excitation by electromagnetic waves at frequencies within the THz range. Dielectric response functions calculated by DFT can be used for the analysis of water contaminants. These functions provide quantitative initial estimates of spectral response features for subsequent adjustment with respect to additional information such as laboratory measurements and other types of theory-based calculations. In addition, with respect to qualitative analysis, DFT calculated absorption spectra provide for molecular level interpretation of response structure. The DFT software GAUSSIAN was used for the calculations of ground state resonance structure presented here.

  16. X-ray studies of interlayer water absorption and mesoporous water transport in a weakly hydrated clay

    NASA Astrophysics Data System (ADS)

    Hemmen, H.; Méheust, Y.; Alme, L. R.; Fossum, J. O.

    2012-04-01

    The swelling of layered smectite clay particles causes changes in the interlayer repetition distance (d-spacing) as a function of temperature and humidity. For the synthetic clay sodium fluorohectorite, hydrodynamically stable hydration states with zero, one and two intercalated monolayers of water have previously been reported, with discrete jumps in d-spacing at the transitions between the hydration states. Keeping the temperature fixed and varying the relative humidity surrounding a powder sample, we find small reproducible d-spacing changes also within the hydration states. These changes are monotonous as a function of relative humidity, and one order of magnitude smaller than the shift in d-spacing that is typical of the transition between two hydration states. We have used this observation to monitor the humidity content of a clay sample in situ, in a non-invasive manner. Imposing a humidity gradient between the two ends of a quasi-one-dimensional weakly-hydrated sample, we use space- and time-resolved X-ray diffraction to follow the transport of water by monitoring the swelling of clay particles. From the series of diffractograms we are able to extract profiles of the relative humidity along the sample length. The time evolution of these profiles describes the transport of water through the mesoporous space inside the clay: An analysis of the measured humidity profiles based on the Boltzmann transform, under certain simplifying assumptions, yields a diffusive behavior that is either normal or possibly weakly anomalous. The humidity profiles also provide the dependence of the effective diffusion coefficient D of the water vapor in the clay mesoporosity as a function of the local concentration of water molecules. The concentration-dependence of D impacts the transport process significantly. Another effect that potentially alters the process is the removal of water molecules from the mesoporosity by intercalation inside the clay grains. Based on 2D finite element simulations we discuss the mechanisms and consequences of those two effects.

  17. Molar absorbance coefficient of pyrene aggregates in water generated by a poly(ethylene oxide) capped at a single end with pyrene.

    PubMed

    Siu, Howard; Duhamel, Jean

    2012-02-01

    The molar absorbance coefficient of ground-state pyrene aggregates (?(E0)(?)) in water generated by a short poly(ethylene oxide) chain labeled at a single end with a 1-pyrenemethoxide unit, namely, the polymeric construct Py?-PEO(2.5K), was determined by a combination of UV-vis absorption and time-resolved fluorescence experiments. Since direct excitation of ground-state pyrene aggregates results in instantaneous excimer emission, whereas excimer formation by diffusive encounters between an excited- and a ground-state pyrene is delayed, acquisition of a pyrene monomer and excimer fluorescence decays with 1 nm increments of the excitation wavelength can probe the subtle effect that the excitation wavelength has on the extent of instantaneous excimer formation. These differences were taken advantage of to determine the fraction f(agg)(f)(?) of the total absorbance of the Py?-PEO(2.5K) solution that is due to ground-state pyrene aggregates. This was achieved by fitting the pyrene monomer and excimer fluorescence decays globally with the model free analysis. For each wavelength, an f(agg)(f)(?) value was obtained which was then related to ?(E0)(?) and f(agg), the molar fraction of aggregated pyrenes that is wavelength independent. These experiments were conducted for three Py?-PEO(2.5K) concentrations yielding three similar ?(E0)(?) spectra as expected since ?(E0)(?) is an intrinsic property of the pyrene aggregates that should not depend on pyrene concentration. The ?(E0)(?) spectra of the pyrene aggregates of Py?-PEO(2.5K) in water were substantially broader and red-shifted compared to that of the pyrene monomer. Its measure provides a simple means to calculate the molar fraction of aggregated pyrene units in a Py?-PEO(2.5K) aqueous solution from the absorption of the solution. This procedure should become widely applicable to determine f(agg) of water-soluble polymers which have been hydrophobically modified with a pyrene derivative and used as models for associative polymers. PMID:22268689

  18. Three-photon absorption in water-soluble ZnS nanocrystals Jun He, Wei Ji,a

    E-print Network

    Wei, Ji

    Three-photon absorption in water-soluble ZnS nanocrystals Jun He, Wei Ji,a and Jun Mi Department on large three-photon absorption 3PA in glutathione-capped ZnS semiconductor nanocrystals NCs , determined-soluble ZnS NCs are synthesized by a modified protocol with a mean diameter of 2.5 nm. Their 3PA cross

  19. Photodissociation of water in the first absorption band: A prototype for dissociation on a repulsive potential energy surface

    Microsoft Academic Search

    V. Engel; V. Staemmler; R. L. Vander Wal; F. F. Crim; R. J. Sension; B. Hudson; P. Andresen; S. Hennig; K. Weide; R. Schinke

    1992-01-01

    The photodissociation of water in the first absorption band, HâO(X) + âÏ â HâO(A¹Bâ) â H(²S) + OH(²II), is a prototype of fast and direct bond rupture in an excited electronic state. It has been investigated from several perspectives-absorption spectrum, final state distributions of the products, dissociation of vibrationally excited states, isotope effects, and emission spectroscopy. The availability of a

  20. Impact of modifying the longwave water vapor continuum absorption model on community Earth system model simulations

    NASA Astrophysics Data System (ADS)

    Turner, D. D.; Merrelli, A.; Vimont, D.; Mlawer, E. J.

    2012-02-01

    The far-infrared (wavelengths longer than 17?m) has been shown to be extremely important for radiative processes in the earth's atmosphere. The strength of the water vapor continuum absorption in this spectral region has largely been predicted using observations at other wavelengths that have been extrapolated using semiempirical approaches such as the Clough-Kneizys-Davies (CKD) family of models. Recent field experiments using new far-infrared instrumentation have supported a factor of 2 decrease in the modeled strength of the foreign continuum at 50?m and a factor of 1.5 increase in the self-continuum at 24?m in the Clough-Kneizys-Davies continuum model (CKD v2.4); these changes are incorporated in the Mlawer-Tobin-CKD continuum model (MT_CKD v2.4). The water vapor continuum in the Community Earth System Model (CESM v1.0) was modified to use the newer model, and the impacts of this change were investigated by comparing output from the original and modified CESM for 20 year integrations with prescribed sea surface temperatures. The change results in an increase in the net upward longwave flux of order 0.5 W m-2between 300 and 400 mb, and a decrease in this flux of about the same magnitude for altitudes below 600 mb. The radiative impact results in a small but statistically significant change in the mean temperature and humidity fields, and also a slight decrease (order 0.5%) of high-cloud amount. The change in the cloud amount modified the longwave cloud radiative forcing, which partially offset the radiative heating caused by the change in the water vapor continuum absorption model.

  1. Investigation of the running-in process and friction coefficient under the lubrication of ionic liquid/water mixture

    NASA Astrophysics Data System (ADS)

    Xie, Guoxin; Liu, Shuhai; Guo, Dan; Wang, Quan; Luo, Jianbin

    2009-04-01

    The tribological properties of three different films commonly used in microelectromechanical systems (MEMS) under the lubrication of ionic liquid (IL)/water mixtures with various concentrations in the running-in process have been investigated. Results show that coefficients of friction (COFs) and wear rates for low temperature silicon oxide (LTO)/Si 3N 4 vary in a similar way to the ones for poly-Si/Si 3N 4 under the lubrications of different IL/water mixtures. In contrast, the differences in COFs and wear rates are more significant in that the COFs and wear rates increase dramatically with the decrease in IL/water concentration in the case of self-mated Si 3N 4, while the differences in COFs and wear rates for the two other tribopairs are relatively small when the concentration is changed. The period of the running-in process reduces with the increase in IL/water concentration for all the tribopairs. Effective hydrodynamic lubrication can be found in the case of Si 3N 4/Si 3N 4 tribopair at higher IL/water concentrations without an evident running-in process, however, such a phenomenon cannot be observed for the other two tribopairs. Different wear mechanisms will also be analyzed in this paper.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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...

  9. 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...

  10. Inversion of shallow water ocean acoustic data using a complex plane-wave reflection coefficient approach

    Microsoft Academic Search

    Steven Stotts; David Knobles; Robert Koch; Adam Cook; David Grant; Karl Focke

    2002-01-01

    A previously reported method of inversion in range-dependent environments using a complex plane-wave approach [Stotts et al., J. Acoust. Soc. Am. 109, 2334 (2001)] has been applied to data analysis. The method separates the propagation in the water column from the interaction with the seabed by first calculating and then storing the eigenray characteristics associated with the assumed known waveguide

  11. Parameterization of near infrared absorption by atmospheric gases

    NASA Technical Reports Server (NTRS)

    Ridgway, W. L.; Arking, A.

    1986-01-01

    An absorption coefficient (k) distribution model is presented for fast calculation of atmospheric transmittances based solely on essential data from line-by-line (LBL) calculations. The absorption at any site is summed over the spectra obtained by LBL calculations. Application of the scaling model is illustrated with sample calculations for 0.72 micron emissions and the 1.36 micron water vapor band. LBL absorption spectra are calculated for the pressure levels 260 mb, 400 mb and 1000 mb.

  12. 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 240 h when WA was 800 g/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

  13. Revisiting the total ion yield x-ray absorption spectra of liquid water microjets

    SciTech Connect

    Saykally, Richard J; Cappa, Chris D.; Smith, Jared D.; Wilson, Kevin R.; Saykally, Richard J.

    2008-02-16

    Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al. (2002 J. Phys.: Condens. Matter 14 L221 and 2001 J. Phys. Chem. B 105 3346) have been revisited in light of new experimental and theoretical efforts by our group. Previously, the TIY spectrum was interpreted as a distinct measure of the electronic structure of the liquid water surface. However, our new results indicate that the previously obtained spectrum may have suffered from as yet unidentified experimental artifacts. Although computational results indicate that the liquid water surface should exhibit a TIY-XAS that is fundamentally distinguishable from the bulk liquid XAS, the new experimental results suggest that the observable TIY-XAS is actually nearly identical in appearance to the total electron yield (TEY-)XAS, which is a bulk probe. This surprising similarity between the observed TIY-XAS and TEY-XAS likely results from large contributions from x-ray induced electron stimulated desorption of ions, and does not necessarily indicate that the electronic structure of the bulk liquid and liquid surface are identical.

  14. Ionic liquid and water molecules diluted in hydrophobic solvent matrix investigated by infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Doseok; Sung, Woongmo; Lee, Jonggwan

    2015-03-01

    Pure ionic liquids ([BMIM]: 1-butyl-3-methylimidazolium, X: Cl and I) and their aqueous solutions were loaded on top of non-polar solvent CCl4, and the infrared spectra of CCl4 phase were taken as a function of time for in-situ probing of the transfer of the ionic liquid and water molecules. We observed clear vibrational bands of methyl and methylene groups of the cations similar to that of bulk ionic liquids. On the other hand, normally strong infrared absorption from C(2)-H and C(4,5)-H vibrations was hardly observable. As these bands work as indicators of specific interaction between the imidazolium core and the halide anions, we concluded that ion pairs are fully dissociated and [BMIM] cations exist as monomers in CCl4. For 1 M of [BMIM]Cl and [BMIM]I aqueous solutions, water molecules transferred into CCl4 also exist mostly as monomers, with a possible existence of anion-bound water molecules inferred from the new band at 3421 cm-1 for [BMIM]Cl, and at 3452 cm- 1 for [BMIM]I. Both transfer rate and saturation amount of ionic liquid molecules are larger for [BMIM]I. For this, we propose that this difference in transfer rate originates from excess ionic liquid molecules at the interface between hydrophlic (aqueous solution) and hydrophobic (CCl4) medium.

  15. Predictions of silicon avalanche photodiode detector performance in water vapor differential absorption lidar

    NASA Technical Reports Server (NTRS)

    Kenimer, R. L.

    1988-01-01

    Performance analyses are presented which establish that over most of the range of signals expected for a down-looking differential absorption lidar (DIAL) operated at 16 km the silicon avalanche photodiode (APD) is the preferred detector for DIAL measurements of atmospheric water vapor in the 730 nm spectral region. The higher quantum efficiency of the APD's, (0.8-0.9) compared to a photomultiplier's (0.04-0.18) more than offsets the higher noise of an APD receiver. In addition to offering lower noise and hence lower random error the APD's excellent linearity and impulse recovery minimize DIAL systematic errors attributable to the detector. Estimates of the effect of detector system parameters on overall random and systematic DIAL errors are presented, and performance predictions are supported by laboratory characterization data for an APD receiver system.

  16. Effect of pH, phosphorus, and water-extractable zinc of soil on plant growth and zinc absorption 

    E-print Network

    Karimian, Najafali

    1970-01-01

    EFFECT OF pH~ PHOSPHORilS, AND WATER-EXTRACTABLE ZINC OF SOIL ON PLANT GROWTH AND ZINC ABSORPT1ON A Thesis Najafali Karimian Submitted to the Graduate College cf Texas ARM University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE December 1970 Major Sub ject: Soil Chemistry EFFECT OF pH, PHOSPHORUS, AND WATER-EXTRACTABLE ZINC OF SOIL ON PLANT GROWTH AND ZINC ABSORPTION A Thesis by NajafaIi Karimian Approved as to sty1e and content by: Chairman Committee...

  17. VARIABILITY OF WATER AND OXYGEN ABSORPTION BANDS IN THE DISK-INTEGRATED SPECTRA OF EARTH

    SciTech Connect

    Fujii, Yuka; Suto, Yasushi [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Turner, Edwin L., E-mail: yuka.fujii@utap.phys.s.u-tokyo.ac.jp [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2013-03-10

    We study the variability of major atmospheric absorption features in the disk-integrated spectra of Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of Earth provided by the EPOXI mission, and find 5%-20% fractional variation of the absorption depths of H{sub 2}O and O{sub 2} 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 data. A difference in the diurnal variability patterns of H{sub 2}O and O{sub 2} bands is ascribed to the differing vertical and horizontal distribution of those molecular species in the atmosphere. On Earth, the inhomogeneous distribution of atmospheric water vapor is due to the existence of its exchange with liquid and solid phases of H{sub 2}O on the planet's surface on a timescale short compared with atmospheric mixing times. If such differences in variability patterns were detected in spectra of Earth-analogs, it would provide the information on the inhomogeneous composition of their atmospheres.

  18. The influence of water vapor on atmospheric exchange measurements with an ICOS* based Laser absorption analyzer

    NASA Astrophysics Data System (ADS)

    Bunk, Rüdiger; Quan, Zhi; Wandel, Matthias; Yi, Zhigang; Bozem, Heiko; Kesselmeier, Jürgen

    2014-05-01

    Carbonyl sulfide and carbon monoxide are both atmospheric trace gases of high interest. Recent advances in the field of spectroscopy have enabled instruments that measure the concentration of the above and other trace gases very fast and with good precision. Increasing the effective path length by reflecting the light between two mirrors in a cavity, these instruments reach impressive sensitivities. Often it is possible to measure the concentration of more than one trace gas at the same time. The OCS/CO2 Analyzer by LGR (Los Gatos Research, Inc.) measures the concentration of water vapor [H2O], carbonyl sulfide [COS], carbon dioxide [CO2] and carbon monoxide [CO] simultaneously. For that the cavity is saturated with light, than the attenuation of light is measured as in standard absorption spectroscopy. The instrument proved to be very fast with good precision and to be able to detect even very low concentrations, especially for COS (as low as 30ppt in the case of COS). However, we observed a rather strong cross sensitivity to water vapor. Altering the water vapor content of the sampled air with two different methods led to a change in the perceived concentration of COS, CO and CO2. This proved especially problematic for enclosure (cuvette) measurements, where the concentrations of one of the above species in an empty cuvette are compared to the concentration of another cuvette containing a plant whose exchange of trace gases with the atmosphere is of interest. There, the plants transpiration leads to a large difference in water vapor content between the cuvettes and that in turn produces artifacts in the concentration differences between the cuvettes for the other above mentioned trace gases. For CO, simultaneous measurement with a UV-Emission Analyzer (AL 5002, Aerolaser) and the COS/CO Analyzer showed good agreement of perceived concentrations as long as the sample gas was dry and an increasing difference in perceived concentration when the sample gas was humidified. The difference in perceived CO concentration showed a clear correlation to the water vapor content in the sample air. For COS we could show that changes in water vapor also impacted on the perceived COS concentrations; the raise of the water vapor concentration would lead to an increasing underestimation of the COS concentration. Drying the air using a Nafion Dryer before entering the COS/CO Analyzer eliminated any water vapor induced artifacts and showed no adverse effects on the quality of the conducted measurements. *Integrated cavity output spectroscopy

  19. Surface activity coefficients of spread monolayers of behenic acid salts at air–water interface

    Microsoft Academic Search

    D. K. Chattoraj; E. Halder; K. P. Das; A. Mitra

    2006-01-01

    The pressure–area isotherms of ionized monolayers of behenic acid at air–water interface at pH 12.0 have been obtained from the Langmuir film balance experiments under various physico-chemical conditions. The value of the measured surface pressure at a given area per molecule is equal to the sum of the ideal pressure, cohesive pressure and electrical pressure. The electrical pressure term is

  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 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

  2. Enhancement of the grafting performance and of the water absorption of cassava starch graft copolymer by gamma radiation

    NASA Astrophysics Data System (ADS)

    Kiatkamjornwong, Suda; Meechai, Nispa

    1997-06-01

    Enhancement of the gamma radiation grafting of acrylonitrile onto gelatinized cassava starch was investigated. Infrared spectrometry was used to follow the chemical changes in the grafting reaction and from saponification. The saponified starch- g-PAN (HSPAN) was then characterized in terms of grafting parameters to provide a guide for the optimum total dose (kGy) and the appropriate ratio of starch/acrylonitrile for a fixed dose rate of 2.5 × 10 -1 kGy/min. Other dose rates were also carried out to obtain the appropriate result of grafting copolymerization and of water absorption. A thin aluminium foil, covering the inner wall of the reaction vessel, was found to be far more effective than any other metal films in the enhancement of the grafting reaction and the water absorption as well. Nitric acid in the medium increases the grafting yield and the water absorption. Methyl ether hydroquinone inhibitor was evaluated for its ability to increase homopolymerization and decrease graft reaction. When styrene was used as a comonomer, it hampered the grafting of acrylonitrile onto starch backbone. The water absorption capacity was improved by freeze-drying the HSPAN. The treatment of the HSPAN with aluminium trichloride hexahydrate was found to enhance the degree of wicking, but to decrease the water absorbency.

  3. On-line preconcentration/determination of zinc from water, biological and food samples using synthesized chelating resin and flame atomic absorption spectrometry.

    PubMed

    Y?lmaz, Sibel; Tokal?o?lu, Serife; Sahan, Serkan; Ulgen, Ahmet; Sahan, Ahmet; Soykan, Cengiz

    2013-04-01

    An on-line flow injection pre-concentration-flame atomic absorption spectrometry method was developed to determine trace zinc in water (tap, dam, and well water), biological (hair and nail), and liver samples. As a solid phase extractant, a synthesized new chelating resin, poly(2-thiozylmethacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propane sulfonic acid) was used. The resin was characterized by Fourier transform infrared spectroscopy, elemental analysis, and surface area by nitrogen sorption. A pre-concentration factor of 40-fold for a sample volume of 12.6 mL was obtained by using the time-based technique. The detection limit for the pre-concentration method was found to be 2.2 ?g L(-1). The precision (as RSD,%) for 10 replicate determinations at the 0.04 ?g mL(-1) Zn concentration was 1.2%. The calibration graph using the pre-concentration system for zinc was linear with a correlation coefficient of 0.998 in the concentration range from 0.005 to 0.05 ?g mL(-1). The applicability and accuracy of the developed method were estimated by the analysis spiked water, biological, liver samples (83-105%), and also certified reference material TMDA-70 (fortified lake water) and SPS-WW1 Batch 111-Wastewater. The results were in agreement with the certified values. PMID:22981635

  4. The room temperature annealing peak in ionomers: Ionic crystallites or water absorption

    SciTech Connect

    Goddard, R.J.; Grady, B.P.; Cooper, S.L. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemical Engineering)

    1994-03-28

    A quaternized diol, 3-(trimethylammonio)-1,2-propanediol neutralized with either bromine or iodine, was used to produce a polyurethane cationomer with a poly(tetramethylene oxide) soft segment and a 4,4[prime]-diphenylmethane diisocyanate hard segment. If those cationomers were annealed at room temperature for a period of approximately 1 month in a desiccator filled with dry CaSO[sub 4], differential scanning calorimetry (DSC) studies showed an endotherm centered near 70 C which was not present in the unannealed polymer and did not reappear upon subsequent cooling and heating cycles in the DSC. Some authors have suggested that a very similar endotherm found in other ionomers, most notably ethylene-methacrylic acid (E-MAA) copolymer ionomers, was due to an order-disorder transition within the ionic aggregates, i.e. ionic crystallite melting. In order to isolate the origin of this endotherm, the local environment around the anion in compression molded bromine neutralized samples was measured using the extended X-ray absorption fine-structure (EXAFS) technique. By measuring the change in the local environment over the temperature range corresponding to the DSC endotherm, it has been shown that this endotherm corresponds to water leaving the bromine coordination shell, rather than ionic crystallite melting. Other studies which include thoroughly drying the material in a vacuum oven below the transition temperature to remove the water suggest that the endotherm is due to the energetic change associated with water leaving the coordination environment of the anion in combination with water vaporization.

  5. The determination of partition coefficients of organic compounds in technical products and waste waters for the estimation of their bioaccumulation potential using reversed phase thin layer chromatography

    Microsoft Academic Search

    Lars O. Renberg; S. Göran Sundström

    1985-01-01

    Reversed phase thin layer chromatography (RPTLC) has been investigated for the estimation of octanol\\/water partition coefficients (P), an important parameter for the prediction of the environmental behaviour of organic chemicals. A strong correlation between P derived from the traditional octanol\\/water system and RPTLC has been established over five orders of magnitude. RPTLC data are likewise correlated to results obtained by

  6. The effects of surface roughness on the contact line friction coefficients of water droplets on micro ?nano-patterned surfaces

    NASA Astrophysics Data System (ADS)

    Cheng, Jiangtao

    2015-03-01

    We report the effects of surface roughness on contact line friction coefficient (CLFC) of water droplets on micro- and nano-patterned surfaces. Both advancing and receding CLFCs have been measured on smooth, one-tier (with micropillars), and two-tier (with CNTs grown on micropillars) surfaces. In comparison with smooth surface, superhydrophobic surfaces can decrease both the advancing and receding CLFCs by more than 10 times. However, droplets on one-tier surfaces exhibit different dynamic behaviors in advancing and receding movements. We investigated the Wenzel-Cassie state transition on micropillar structures and found that the receding motion of a droplet on micropillars is dominated by the Wenzel model with significant receding contact line pinning, which leads to higher receding CLFC. However, rolling mechanism of liquid particles near the advancing contact line controls the advancing motion of a droplet on micropillars. There is a high tendency for an advancing droplet to exhibit Cassie-type behavior on one-tier surfaces and hence advancing CLFC is considerably mitigated. On two-tier superhydrophobic surfaces, it is the Cassie-Baxter behavior that dominates both the advancing and receding contact line motions giving rise to less friction coefficients.

  7. Ultra reliable infrared absorption water vapor detection through the all-electronic feedback stabilization

    NASA Astrophysics Data System (ADS)

    Zhu, C. G.; Chang, J.; Wang, P. P.; Wang, Q.; Wei, W.; Tian, J. Q.; Chang, H. T.; Liu, X. Z.; Zhang, S. S.

    2014-03-01

    Single-beam balanced radiometric detection (BRD) system with all-electronic feedback stabilization has been proposed for high reliability water vapor detection under rough environmental conditions, which is insensitive to the fluctuation of transmission loss of light. The majority of photocurrent attenuation caused by the optical loss can be effectively compensated by automatically adjusting the splitting ratio of probe photocurrent. Based on the Ebers-Moll model, we present a theoretical analysis which can be suppressed the photocurrent attenuation caused by optical loss from 0.5552 dB to 0.0004 dB by using the all-electronic feedback stabilization. The deviation of the single-beam BRD system is below 0.29% with the bending loss of 0.31 dB in fiber, which is obviously lower than the dual-beam BRD system (5.96%) and subtraction system (11.3%). After averaging and filtering, the absorption sensitivity of water vapor at 1368.597 nm has been demonstrated, which is 7.368×10-6.

  8. Light tracking through ice and water -- Scattering and absorption in heterogeneous media with Photonics

    E-print Network

    J. Lundberg; P. Miocinovic; K. Woschnagg; T. Burgess; J. Adams; S. Hundertmark; P. Desiati; P. Niessen

    2007-08-29

    In the field of neutrino astronomy, large volumes of optically transparent matter like glacial ice, lake water, or deep ocean water are used as detector media. Elementary particle interactions are studied using in situ detectors recording time distributions and fluxes of the faint photon fields of Cherenkov radiation generated by ultra-relativistic charged particles, typically muons or electrons. The Photonics software package was developed to determine photon flux and time distributions throughout a volume containing a light source through Monte Carlo simulation. Photons are propagated and time distributions are recorded throughout a cellular grid constituting the simulation volume, and Mie scattering and absorption are realised using wavelength and position dependent parameterisations. The photon tracking results are stored in binary tables for transparent access through ANSI-C and C++ interfaces. For higher-level physics applications, like simulation or reconstruction of particle events, it is then possible to quickly acquire the light yield and time distributions for a pre-specified set of light source and detector properties and geometries without real-time photon propagation. In this paper the Photonics light propagation routines and methodology are presented and applied to the IceCube and Antares neutrino telescopes. The way in which inhomogeneities of the Antarctic glacial ice distort the signatures of elementary particle interactions, and how Photonics can be used to account for these effects, is described.

  9. Mechanical- and oil-durable superhydrophobic polyester materials for selective oil absorption and oil/water separation.

    PubMed

    Wu, Lei; Zhang, Junping; Li, Bucheng; Wang, Aiqin

    2014-01-01

    The low stability and complicated fabrication procedures seriously hindered practical applications of superhydrophobic materials. Here we present a facile approach for preparing durable superhydrophobic polyester materials by dip-coating in a nanocomposite solution of polymerized tetraethoxysilane and n-hexadecyltriethoxysilane. The coated samples exhibit excellent superhydrophobicity, superoleophilicity, mechanical and chemical stabilities. This is attributed to the tight binding of the nanocomposite on the polyester fibers and the inherent stability of silicone. The coated samples can quickly absorb petrol, diesel and crude oil, and show very high selectivity in oil/water separation. In addition, the coated samples could maintain their superhydrophobicity, oil absorption capacity and oil/water selectivity after harsh mechanical damage, 90 days of immersion in oils and ten cycles of absorption-desorption. Moreover, this approach is simple and can be easily scaled up for producing samples on a large size, which makes it very promising for practical oil absorption. PMID:24183438

  10. Effect of morphology and solvent on two-photon absorption of nano zinc oxide

    SciTech Connect

    Kavitha, M.K. [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); Haripadmam, P.C.; Gopinath, Pramod; Krishnan, Bindu [Department of Physics, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India); John, Honey, E-mail: honey@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695547, Kerala (India)

    2013-05-15

    Highlights: ? ZnO nanospheres and triangular structures synthesis by novel precipitation technique. ? The effect of precursor concentration on the size and shape of nano ZnO. ? Open aperture Z-scan measurements of the ZnO nanoparticle dispersions. ? Nanospheres exhibit higher two photon absorption coefficient than triangular nanostructures. ? Nanospheres dispersed in water exhibit higher two photon absorption coefficient than its dispersion in 2-propanol. - Abstract: In this paper, we report the effect of morphology and solvent on the two-photon absorption of nano zinc oxide. Zinc oxide nanoparticles in two different morphologies like nanospheres and triangular nanostructures are synthesized by novel precipitation technique and their two-photon absorption coefficient is measured using open aperture Z-scan technique. Experimental results show that the zinc oxide nanospheres exhibit higher two-photon absorption coefficient than the zinc oxide triangular nanostructures. The zinc oxide nanospheres dispersed in water exhibit higher two-photon absorption coefficient than that of its dispersion in 2-propanol. The zinc oxide nanospheres dispersed in water shows a decrease in two-photon absorption coefficient with an increase in on-axis irradiance. The result confirms the dependence of shape and solvent on the two-photon absorption of nano zinc oxide.

  11. 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.

  12. Photothermal techniques applied to the determination of the water vapor diffusion coefficient and thermal diffusivity of edible films.

    PubMed

    Aguilar-Mendez, M A; Martin-Martinez, E San; Morales, J E; Cruz-Orea, A; Jaime-Fonseca, M R

    2007-04-01

    Water vapor diffusion coefficient (WVDC) and thermal diffusivity (alpha) were determined in gelatin-starch films through photothermal techniques. The effect of different variables in the elaboration of these films, such as starch and glycerol concentrations and pH, were evaluated through the response surface methodology. The results indicated that an increase in the glycerol concentration and pH favored the WVDC of the films. On the other hand, alpha was influenced principally by the starch content and pH of the film-forming solution. The minimum alpha value was 4.5 x 10(-4) cm2/s, which is compared with alpha values reported for commercial synthetic polymers. PMID:17420552

  13. Atmospheric pre-corrected differential absorption techniques to retrieve columnar water vapor: Application to AVIRIS 91/95 data

    SciTech Connect

    Schlaepfer, D. [Univ. of Zuerich (Switzerland). Dept. of Geography; Borel, C.C. [Los Alamos National Lab., NM (United States); Keller, J. [Paul Scherrer Institut, Villigen (Switzerland)] [and others

    1996-03-01

    Water vapor is one of the main forces for weather development as well as for mesoscale air transport processes. The monitoring of water vapor is therefore an important aim in remote sensing of the atmosphere. Current operational systems for water vapor detection use primarily the emission in the thermal infrared (AVHRR, GOES, ATSR, Meteosat) or in the microwave radiation bands (DMSP). The disadvantage of current satellite systems is either a coarse spatial (horizontal) resolution ranging from one to tens of kilometers or a limited insight into the lower atmosphere. Imaging spectrometry on the other hand measures total column water vapor contents at a high spatial horizontal resolution and has therefore the potential of filling these gaps. The sensors of the AVIRIS instrument are capable of acquiring hyperspectral data in 224 bands located in the visible and near infrared at 10 run resolution. This data includes information on constituents of the earth`s surface as well as of the atmosphere. The optical measurement of water vapor can be performed using sensor channels located in bands or lines of the absorption spectrum. The AVIRIS sensor has been used to retrieve water vapor and with less accuracy carbon dioxide, oxygen and ozone. To retrieve the water vapor amount, the so called differential absorption technique has been applied. The goal of this technique is to eliminate background factors by taking a ratio between channels within the absorption band and others besides the band. Various rationing methods on the basis of different channels and calculation techniques were developed. The influence of a trace gas of interest on the radiance at the sensor level is usually simulated by using radiative transfer codes. In this study, spectral transmittance and radiance are calculated by MODTRAN3 simulations with the new DISORT option. This work testS the best performing differential absorption techniques for imaging spectrometry of tropospheric water vapor.

  14. Optical absorption spectra of waters from the Orinoco River outflow: Terrestrial input of colored organic matter to the Caribbean

    Microsoft Academic Search

    N. V. Blough; O. C. Zafiriou; J. Bonilla

    1993-01-01

    An extensive series of optical absorption spectra were recorded for waters in the eastern Caribbean Sea, the Gulf of Paria, and the Orinoco River Estuary during the high-flow period of the Orinoco River in the Fall of 1988. Evidence for high levels of dissolved, colored organic matter (COM) was found throughout the eastern Caribbean, with these levels increasing substantially at

  15. Effects of stress waveform and water absorption on the fatigue strength of angle-ply aramid fiber\\/epoxy composites

    Microsoft Academic Search

    K. Komai; K. Minoshima; K. Tanaka; T. Tokura

    2002-01-01

    The influences of stress waveform and water absorption on the tension–tension fatigue fracture behavior were investigated in ±45° angle-ply laminates of aramid fiber reinforced epoxy matrix composite. For dry specimens, the fatigue strength under negative pulse waveform was higher than that under the positive pulse waveform. Rotation of fibers to the longitudinal direction, which resulted from creep deformation caused by

  16. Evaluation of Plasma-Deposited Hydrophobic Coatings on Pigment-Coated Paper for Reduced Dampening Water Absorption

    Microsoft Academic Search

    M. Pykönen; K. Johansson; M. Dubreuil; D. Vangeneugden; G. Ström; P. Fardim; M. Toivakka

    2010-01-01

    Hydrophobic plasma coatings were deposited on pigment-coated paper with the purpose of reducing dampening water absorption and create uniform surface chemistry. The influence of plasma coatings on sheet-fed offset printability was also studied. Three plasma chemistries, fluorocarbon, organosilicon and hydrocarbon, were used to adjust the hydrophobicity of paper surface. The plasma coatings reduced, and in some cases prevented, the dampening

  17. ATOMIC ABSORPTION SPECTROMETRIC DETERMINATION OF ARSENITE IN WATER SAMPLES BY GRAPHITE FURNACE AFTER EXTRACTION WITH AMMONIUM SEC-BUTYLDITHIOPHOSPHATE

    EPA Science Inventory

    Arsenite - but not arsenate, methylarsonic acid, or dimethylarsinic acid - is extracted from water samples by 5 mL of a 0.01M hexane solution of sec-dibutylthiophosphate. A 10 microliters aliquot of the extract is injected into an atomic absorption spectrometer with a graphic fur...

  18. Feasibility of tropospheric water vapor profiling using infrared heterodyne differential absorption lidar

    SciTech Connect

    Grund, C.J.; Hardesty, R.M. [NOAA Environmental Technology Lab., Boulder, CO (United States); Rye, B.J. [Univ. of Colorado, Boulder, CO (United States). Cooperative Institute for Research in Environmental Sciences (CU/NOAA)

    1995-04-03

    Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution, acquired over long periods at low operational and maintenance cost, are fundamental to the success of the ARM CART program. 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. Application of profiles acquired with current techniques, have, to date, been limited by vertical resolution and uniqueness of solution [e.g. high resolution infrared (IR) Fourier transform radiometry], poor spatial and temporal coverage and high operating cost (e.g. radiosondes), or diminished daytime performance, lack of eye-safety, and high maintenance cost (e.g. Raman lidar). Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the study reported here, we develop DIAL system performance models and examine the potential of to solve some of the shortcomings of previous methods using parameterizations representative of current technologies. These models are also applied to diagnose and evaluate other strengths and weaknesses unique to the DIAL method for this application. This work is to continue in the direction of evaluating yet smaller and lower-cost laser diode-based systems for routine monitoring of the lower altitudes using photon counting detection methods. We regard the present report as interim in nature and will update and extend it as a final report at the end of the term of the contract.

  19. Infrared reflection absorption spectroscopy of amphipathic model peptides at the air/water interface.

    PubMed

    Kerth, Andreas; Erbe, Andreas; Dathe, Margitta; Blume, Alfred

    2004-06-01

    The linear sequence KLAL (KLALKLALKALKAALKLA-NH(2)) and its corresponding d,l-isomers k(9)a(10)-KLAL (KLALKLALkaLKAALKLA-NH(2)) and l(11)k(12)-KLAL (KLALKLALKAlkAALKLA-NH(2)) are model compounds for potentially amphipathic alpha-helical peptides which are able to bind to membranes and to increase the membrane permeability in a structure- and target-dependent manner (Dathe and Wieprecht, 1999) We first studied the secondary structure of KLAL and its analogs bound to the air/water using infrared reflection absorption spectroscopy. For the peptide films the shape and position of the amide I and amide II bands indicate that the KLAL adopts at large areas per molecule an alpha-helical secondary structure, whereas at higher surface pressures or smaller areas it converts into a beta-sheet structure. This transition could be observed in the compression isotherm as well as during the adsorption at the air/water interface from the subphase as a function of time. The secondary structures are essentially orientated parallel to the air/water interface. The analogs with d-amino acids in two different positions of the sequence, k(9)a(10)-KLAL and l(11)k(12)-KLAL, form only beta-sheet structures at all surface pressures. The observed results are interpreted using a comparison of hydrophobic moments calculated for alpha-helices and beta-sheets. The differences between the hydrophobic moments calculated using the consensus scale are not large. Using the optimal matching hydrophobicity scale or the whole-residue hydrophobicity scale the beta-sheet even has the larger hydrophobic moment. PMID:15189871

  20. Partition coefficients of environmentally important phenols in a supercritical carbon dioxide-water system from cocurrent extraction without analysis of the compressible phase.

    PubMed

    Karásek, Pavel; Pól, Jaroslav; Planeta, Josef; Roth, Michal; Vejrosta, Jirí; Wicar, Stanislav

    2002-08-15

    Partition coefficients of phenol, salicylic acid, and several environmentally important chloro- and nitrophenols in a supercritical CO2-water system were measured using direct cocurrent extraction of aqueous solutions of the individual solutes with CO2. Partitioning data on the nitrophenols and salicylic acid were obtained for the first time. To bypass the troublesome and error-prone analysis of the CO2-rich phase, the present method employed only the solute concentrations in the aqueous phase before and after extraction to determine the partition coefficient. Unlike most previous engineering studies of phenol partitioning in a CO2-water system, the concentrations of phenolic solutes approached infinite dilution in both phases. This makes the results relevant to analytical-scale SFE of environmental water samples with CO2. Because of effective infinite dilution of the solutes, the partition coefficients provide a direct measure of relative CO2-philicity/hydrophilicity of the individual phenols. Compared to the octanol-water partition coefficients of substituted phenols, the CO2-water partition coefficients are more sensitive to substitution in the position neighboring the hydroxyl group. PMID:12199606

  1. Measurement of CH_3D Absorption Cross Sections, Pressure Broadening, and Shft Coefficients in the 1.65 ?m Spectral Region by Using Continuous Ave Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tang, Yongxin; Yang, Shaoyue L.; Lehmann, Kevin K.; Benner, D. Chris

    2011-06-01

    Quantitative spectroscopy of CH_3D in the near-IR is of importance for an ongoing project to build an instrument to measure the H/D isotopic ratio of methane gas. Continuous-wave cavity ring-down spectroscopy (CRDS) has been used to examine the absorption cross sections, the pressure-broadening and pressure-shift coefficients at around 1652 nm. The absorption cross sections of CH_3D were quantified in the wavenumber region between 6046 and 6060 Cm-1. The maximum peak is located at 6055.17 Cm-1, which gives (8.58 ± 0.37) × 10-21 cm^2/molecule at the total pressure of ˜ 8.2 Torr of the N_2 buffer gas. By using the small step size of the laser wavenumber scan, we measured the pressure-broadening effects, and the pressure-shift effects, on CH_4 and CH_3D absorption lines. The N_2, O_2 and CO_2 pressure broadening coefficients of CH_3D are 0.058, 0.054 and 0.049 Cm-1/atm, respectively, at the wavenumber we employed. Under the experimental conditions we used, N_2 and O_2 have very similar pressure broadening effects, and their effects on CH_3D is very similar to those of CH_4. At the wavenumber we employed, the same values of N_2 and O_2 pressure-shift coefficient , - 0.012 Cm-1/atm, and a little higher value of CO_2, - 0.013 Cm-1/atm, were found.

  2. An alternative approach for the use of water solubility of nonionic pesticides in the modeling of the soil sorption coefficients.

    PubMed

    dos Reis, Ralpho Rinaldo; Sampaio, Silvio César; de Melo, Eduardo Borges

    2014-04-15

    The collection of data to study the damage caused by pesticides to the environment and its ecosystems is slowly acquired and costly. Large incentives have been established to encourage research projects aimed at building mathematical models for predicting physical, chemical or biological properties of environmental interest. The organic carbon normalized soil sorption coefficient (K(oc)) is an important physicochemical property used in environmental risk assessments for compounds released into the environment. Many models for predicting logK(oc) that have used the parameters logP or logS as descriptors have been published in recent decades. The strong correlation between these properties (logP and logS) prevents them from being used together in multiple linear regressions. Because the sorption of a chemical compound in soil depends on both its water solubility and its water/organic matter partitioning, we assume that models capable of combining these two properties can generate more realistic results. Therefore, the objective of this study was to propose an alternative approach for modeling logK(oc), using a simple descriptor of solubility, here designated as the logarithm of solubility corrected by octanol/water partitioning (logS(P)). Thus, different models were built with this descriptor and with the conventional descriptors logP and logS, alone or associated with other explanatory variables representing easy-to-interpret physicochemical properties. The obtained models were validated according to current recommendations in the literature, and they were compared with other previously published models. The results showed that the use of logS(p) instead of conventional descriptors led to simple models with greater statistical quality and predictive power than other more complex models found in the literature. Therefore, logS(P) can be a good alternative to consider for the modeling of logK(oc) and other properties that relate to both solubility and water/organic matter partitioning. PMID:24525068

  3. The effect of ambient temperature on the surface area of components of an air-cooled lithium bromide\\/water absorption unit

    Microsoft Academic Search

    M. Mostafavi; B. Agnew

    1996-01-01

    The escalating cost of energy during this decade has made co-generation very popular. When cooling is required for either space conditioning or industrial processes, absorption chillers which use waste heat can be utilised. Much of the work is concentrated on the water-cooled absorption chiller. Since countries with hot and dry climates are often short of water, it will also be

  4. Diffusion Coefficients and Viscosities of CO2 + H2O, CO2 + CH3OH, NH3 + H2O, and NH3 + CH3OH Liquid Mixtures

    Microsoft Academic Search

    Marco J. W. Frank; Johannes A. M. Kuipers; Swaaij van W. P. M

    1996-01-01

    To evaluate quantitatively the results of gas-liquid absorption experiments, accurate liquid-phase diffusion coefficients and viscosities are needed. In this paper experimental values of these quantities will be reported for the binary systems carbon dioxide + water, carbon dioxide + methanol, ammonia + water, and ammonia + methanol. The diffusion coefficients have been measured using the Taylor-Aris dispersion method, and the

  5. Diffusion coefficients and viscosities of COâ + HâO, COâ + CHâOH, NHâ + HâO, and NHâ + CHâOH liquid mixtures

    Microsoft Academic Search

    M. J. W. Frank; J. A. M. Kuipers; W. P. M. van Swaaij

    1996-01-01

    To evaluate quantitatively the results of gas-liquid absorption experiments, accurate liquid-phase diffusion coefficients and viscosities are needed. In this paper experimental values of these quantities will be reported for the binary systems carbon dioxide + water, carbon dioxide + methanol, ammonia + water, and ammonia + methanol. The diffusion coefficients have been measured using the Taylor-Aris dispersion method, and the

  6. Effect of fibre and coupling agent contents on water absorption and flexural modulus of wood fibre polyethylene composites

    NASA Astrophysics Data System (ADS)

    Tissandier, C.; Zhang, Y.; Rodrigue, D.

    2014-05-01

    In two previous studies, wood fiber-reinforced polymer composites (WPC) were prepared via melt processing. In particular, a response surface strategy of a 20 run optimal design for these three factors was adopted. It was found that for these WPC mixing torque, melt viscosity, Young's modulus and tensile stress at break were related to the type of wood used, as well as wood and coupling agent contents. In addition, thermal properties and strain at break were mainly affected by wood and coupling agent contents. Here, a more complete characterization of these WPC under extreme environmental conditions is performed. In particular, the effect of coupling agent content, wood fibre content and wood fibre type on water absorption and flexural modulus are reported under different water immersion time and temperature. The results show that water absorption is influenced by all the parameters studied, while flexural modulus is mainly influenced by wood content and immersion temperature.

  7. Recent advances in carrier-mediated intestinal absorption of water-soluble vitamins.

    PubMed

    Said, Hamid M

    2004-01-01

    Significant progress has been made in recent years toward understanding the mechanisms and regulation of intestinal absorption of water-soluble vitamins from the diet, especially those that are transported by a specialized carrier-mediated mechanism (i.e., ascorbic acid, biotin, folate, riboflavin, thiamin, and pyridoxine). The driving force involved in the uptake events and the molecular identity of the systems involved have been identified for a number of these vitamins. In addition, information about regulation of the uptake process of these micronutrients by intracellular and extracellular factors has been forthcoming. Furthermore, the 5' regulatory region of the genes that encode a number of these transporters has been characterized, thus providing information about transcriptional regulation of the transport events. Also of interest is the identification of existence of carrier-mediated mechanisms in human colonocytes that are capable of absorbing some of the vitamins that are synthesized by normal microflora of the large intestine. Although the contribution of the latter source of vitamins toward overall host nutrition is not clear and requires further investigations, it is highly likely that it does contribute toward the cellular homeostasis of these vitamins in the localized colonocytes. PMID:14977409

  8. Ultra Narrowband Optical Filters for Water Vapor Differential Absorption Lidar (DIAL) Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Stenholm, Ingrid; DeYoung, Russell J.

    2001-01-01

    Differential absorption lidar (DIAL) systems are being deployed to make vertical profile measurements of atmospheric water vapor from ground and airborne platforms. One goal of this work is to improve the technology of such DIAL systems that they could be deployed on space-based platforms. Since background radiation reduces system performance, it is important to reduce it. One way to reduce it is to narrow the bandwidth of the optical receiver system. However, since the DIAL technique uses two or more wavelengths, in this case separated by 0.1 nm, a fixed-wavelength narrowband filter that would encompass both wavelengths would be broader than required for each line, approximately 0.02 nm. The approach employed in this project is to use a pair of tunable narrowband reflective fiber Bragg gratings. The Bragg gratings are germanium-doped silica core fiber that is exposed to ultraviolet radiation to produce index-of-refraction changes along the length of the fiber. The gratings can be tuned by stretching. The backscattered laser radiation is transmitted through an optical circulator to the gratings, reflected back to the optical circulator by one of the gratings, and then sent to a photodiode. The filter reflectivities were >90 percent, and the overall system efficiency was 30 percent.

  9. Profiling tropospheric water vapour with a coherent infrared differential absorption lidar: a sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Baron, Philippe; Ishii, Shoken; Mizutani, Kohei; Itabe, Toshikazu; Yasui, Motoaki

    2012-11-01

    In the last decade the precision of coherent Doppler differential absorption lidar (DIAL) has been greatly improved in near and middle infra-red domains for measuring greenhouse gases such as CO2, CH4 and winds. The National Institute of Information and Communications Technology (NICT, Japan) has developed and is operating a CO2 and wind measuring ground-based coherent DIAL at 2.05 ?m (4878 cm-1). The application of this technology from space is now considered. In this analysis we study the use of the NICT DIAL for profiling tropospheric water vapour from space. We present the methodology to select the spectral lines and summarized the results of the selected lines between 4000 and 7000 cm-1. The choice of the frequency offset, the pulse energy and repetition frequency are discussed. Retrieval simulations from the line at 4580 cm-1 (2.18 ?m) suitable for the boundary layer and the stronger one at 5621 cm-1 (1.78 ?m) for sounding the boundary layer and the middle troposphere, are shown.

  10. Measuring Hydroxyl Radicals during the Oxidation of Methane, Ethane, Ethylene, and Acetylene in a Shock Tube Using UV Absorption Spectroscopy 

    E-print Network

    Aul, Christopher J

    2013-05-02

    . Tests were completed using the absorption coefficient correlation on stoichiometric mixtures of methane, methane and water, ethane, ethylene, and acetylene to compare against a comprehensive, detailed chemical kinetics mechanism which considers up...

  11. Linear and nonlinear optical absorption coefficients and refractive index changes in GaN/AlxGa(1-x)N double quantum wells operating at 1.55 ?m

    NASA Astrophysics Data System (ADS)

    Dakhlaoui, Hassen

    2015-04-01

    In the present paper, the linear and nonlinear optical absorption coefficients and refractive index changes between the ground and the first excited states in double GaN/AlxGa(1-x)N quantum wells are studied theoretically. The electronic energy levels and their corresponding wave functions are obtained by solving Schrödinger-Poisson equations self-consistently within the effective mass approximation. The obtained results show that the optical absorption coefficients and refractive index changes can be red- and blue-shifted through varying the left quantum well width and the aluminum concentration xb2 of the central barrier, respectively. These structural parameters are found to present optimum values for carrying out the transition of 0.8 eV (1.55 ?m). Furthermore, we show that the desired transition can also be achieved by replacing the GaN in the left quantum well with AlyGa(1-y)N and by varying the aluminum concentration yAl. The obtained results give a new degree of freedom in optoelectronic device applications such as optical fiber telecommunications operating at (1.55 ?m).

  12. The influence of recycled expanded polystyrene (EPS) on concrete properties: Influence on flexural strength, water absorption and shrinkage

    NASA Astrophysics Data System (ADS)

    Elsalah, Jamaleddin; Al-Sahli, Yosra; Akish, Ahmed; Saad, Omar; Hakemi, Abdurrahman

    2013-12-01

    Expanded polystyrene waste in a granular form was used as a lightweight aggregate in order to produce lightweight concretë Lightweight EPS concrete composites were produced by replacing the coarse aggregate, either partially or fully with equal volume of EPS aggregates. The coarse aggregate replacements levels used were 25, 50, 75, and 100%, which corresponded to (9.20, 18.40, 27.60, and 36.8%) from total volume. The investigation is directed towards the development and performance evaluation of the concrete composites containing EPS aggregates, without addition of either bonding additives, or super-plasticizers on some concrete properties such as flexure strength, water absorption and change in length (or shrinkage). Experimental results showed that a density reduction of 12% caused flexure strength to decrease by 25.3% at a replacement level of 25% EPS. However, the reduction percentage strongly depends upon the replacement level of EPS granules. Moreover, the lower strength concretes showed a higher water absorption values compared to higher strength concrete, i.e., increasing the volume percentage of EPS increases the water absorption as well as the negative strain (shrinkage). The negative strain was higher at concretes of lower density (containing a high amount of EPS aggregate). The water to cement ratio of EPS aggregate concrete is found to be slightly lower than that of conventional concrete.

  13. Prediction of 1-octanol-water and air-water partition coefficients for nitro-aromatic compounds from molecular dynamics simulations.

    PubMed

    Bhatnagar, Navendu; Kamath, Ganesh; Potoff, Jeffrey J

    2013-05-01

    United-atom force fields, based on the Transferable Potentials for Phase Equilibria (TraPPE), are developed for twelve nitro-aromatic compounds, which include 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 3-nitrotoluene (3-NT), 4-nitrotoluene (4-NT), 1,3-dinitrobenzene (1,3-DNB), 1,4-dinitrobenzene (1,4-DNB), 2,4-dinitroanisole (DNAN), 1,3,5-trinitrobenzene (TNB), 2,4,6-trinitrotoluene (TNT), 2-nitroanisole (2-NAN), 4-nitroanisole (4-NAN) and n-methyl-p-nitroaniline (MNA). 1-Octanol-water and air-water partition coefficients are predicted for the optimized TraPPE-UA force field with adaptive biasing force molecular dynamics simulations, and compared to available experimental data. Log Kow values are predicted with an average absolute deviation of 0.2 log units, while Henry's law constants are predicted to with an average absolute deviation of 0.5 log units. Two additional models are presented for energetic materials with five membered rings for which no experimental data are available in the open literature: 3,5-dinitropyrazole (DNP) and 3-nitro-1,2,4-triazole-5-one (NTO). Investigation of the local microstructure around each solute reveals that 1-octanol is able to form hydrogen bonded chains around the solute, while little organized microstructure was observed around the solutes in water. PMID:23529577

  14. Role of glucose transporters in the intestinal absorption of gastrodin, a highly water-soluble drug with good oral bioavailability.

    PubMed

    Cai, Zheng; Huang, Juan; Luo, Hui; Lei, Xiaolu; Yang, Zhaoxiang; Mai, Yang; Liu, Zhongqiu

    2013-07-01

    Gastrodin, a sedative drug, is a highly water-soluble phenolic glucoside with poor liposolubility but exhibits good oral bioavailability. The current study aims to investigate whether glucose transporters (GLTs) are involved in the intestinal absorption of gastrodin. The intestinal absorption kinetics of gastrodin was determined using the rat everted gut sac model, the Caco-2 cell culture model and the perfused rat intestinal model. In vivo pharmacokinetic studies using diabetic rats with high GLT expression were performed. Saturable intestinal absorption of gastrodin was observed in rat everted gut sacs. The apparent permeability (Papp) of gastrodin from the apical (A) to basolateral (B) side in Caco-2 cells was two-fold higher than that from B to A. Glucose or phlorizin, a sodium-dependent GLT (SGLT) inhibitor, reduced the absorption rates of gastrodin from perfused rat intestines. In vivo pharmacokinetic studies showed that the time of maximum plasma gastrodin concentration (Tmax) was prolonged from 28 to 72 min when orally co-administered with four times higher dose of glucose. However, the Tmax of gastrodin in diabetic rats was significantly lowered to 20 min because of the high intestinal SGLT1 level. In conclusion, our findings indicate that SGLT1 can facilitate the intestinal absorption of gastrodin. PMID:23480725

  15. Remote sensing of the absorption coefficients and chlorophyll a concentration in the United States southern Middle Atlantic Bight from SeaWiFS and MODIS-Aqua

    Microsoft Academic Search

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

    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 United States southern Middle Atlantic Bight (SMAB) were applied to improve retrievals of satellite ocean color products from the Sea-viewing

  16. Measurement of gas/water uptake coefficients for trace gases active in the marine environment. [Annual report

    SciTech Connect

    Davidovits, P. [Boston Coll., Chestnut Hill, MA (United States). Dept. of Chemistry; Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean`s surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry`s law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  17. Analysis of Differences in Void Coefficient Predictions for Mixed-Oxide-Fueled Tight-Pitch Light Water Reactor Cells

    SciTech Connect

    Unesaki, Hironobu [Kyoto University (Japan); Shiroya, Seiji [Kyoto University (Japan); Kanda, Keiji [Kyoto University (Japan); Cathalau, Stephane [Commissariat a l'Energie Atomique (France); Carre, Franck-Olivier [Commissariat a l'Energie Atomique (France); Aizawa, Otohiko [Musashi Institute of Technology (Japan); Takeda, Toshikazu [Osaka University (Japan)

    2000-05-15

    Analysis of the benchmark problems on the void coefficient of mixed-oxide (MOX)-fueled tight-pitch cells has been performed using the Japanese SRAC code system with the JENDL-3.2 library and the French APOLLO-2 code with the CEA93 library based on JEF-2.2. The benchmark problems have been specified to investigate the physical phenomena occurring during the progressive voidage of MOX-fueled tight-pitch lattices, such as high conversion light water reactor lattices, and to evaluate the impact of nuclear data and calculational methods. Despite the most recently compiled nuclear data libraries and the sophisticated calculation schemes employed in both code systems, the k{sub {infinity}} and void reactivity values obtained by the two code systems show considerable discrepancy especially in the highly voided state. The discrepancy of k{sub {infinity}} values shows an obvious dependence on void fraction and also has been shown to be sensitive to the isotopic composition of plutonium. The observed discrepancies are analyzed by being decomposed into contributing isotopes and reactions and have been shown to be caused by a complicated balance of both negative and positive components, which are mainly attributable to differences in a limited number of isotopes including {sup 239}Pu, {sup 241}Pu, {sup 16}O, and stainless steel.

  18. Trace-element partition coefficients in the calcite-water system and their paleoclimatic significance in cave studies

    NASA Astrophysics Data System (ADS)

    Gascoyne, Melvyn

    1983-02-01

    Speleothems (stalactites, stalagmites) formed in limestone caves have been found to contain much information on the timing and intensity of past climates, from analysis of their U, Th, 13C and 18O contents. Because the incorporation of certain trace elements (e.g., Mg, Mn and Zn) in calcite is known to be temperature-dependent, it may be possible to use variations in trace-metal content of fossil speleothems as an alternative paleotem-perature indicator. Using specially developed ion-exchange sampling techniques, analysis of trace-metal content of seepage water and associated fresh calcite deposits in caves in Vancouver Island and Jamaica shows that Mg is distributed between phases in a consistent manner within the temperature regimes of the caves (7° and 23°C, respectively). Average values of the distribution coefficient for Mg are respectively 0.017 and 0.045 at these temperatures. These results indicate that the Mg content of calcite varies directly with temperature and in a sufficiently pronounced manner that a 1°C rise in depositional temperature of a speleothem containing 500 ppm Mg, at ˜10°C, would be seen as an increase of ˜35ppm Mg — a readily determinable shift. Other factors affecting Mg content of a speleothem are considered.

  19. Rapid method for estimating the octanol--water partition coefficient (log P ow) by microemulsion electrokinetic chromatography.

    PubMed

    Poole, S K; Durham, D; Kibbey, C

    2000-08-01

    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 sodium dodecyl sulfate (1.4% w/v), butan-1-ol (8% v/v) and heptane (1.2% v/v). Neutral and basic compounds are analyzed using a fused-silica capillary column with a 50 mM sodium phosphate-sodium borate (3:2) buffer at pH 10. Weakly acid compounds require the use of sulfonated silica capillary column and a 50 mM sodium phosphate buffer at pH 3. For 29 varied neutral and weakly basic compounds the average error between log Pow estimated using MEEKC and literature values was +/-0.12 over a log Pow range from 0.3 to 5.8. PMID:10997707

  20. Determination of poly(dimethyl)siloxane-water partition coefficients for selected hydrophobic organic chemicals using 14C-labeled analogs.

    PubMed

    Yang, Ze-Yu; Greenstein, Darrin; Zeng, Eddy Y; Maruya, Keith A

    2007-04-27

    Aqueous solutions of (14)C-labeled analogs of seven hydrophobic organic chemicals (HOCs) were subject to solid-phase microextraction (SPME) under static conditions to assess their multi-compartment distribution and to compare poly(dimethyl)siloxane (PDMS)-water partition coefficients (K(f) values) with previously reported values. To accomplish this, a protocol for quantitative desorption of radiolabelled HOCs from SPME fibers using hexane was developed. Time series extractions indicated that loading of SPME fibers had reached steady-state by day 8 for PCBs 52, 77 and 153, phenanthrene, benzo[a]pyrene, p,p'-DDT and p,p'-DDE. The recovery of spiked radioactivity among the (residual) aqueous phase, the PDMS coating, and all remaining wetted experimental surfaces ranged between 80 and 120%. K(f) values based on (14)C-labeled analogs were in good agreement with previously published values that were determined at (or closely approaching) equilibrium conditions and without significant chemical depletion and/or uncorrected system losses. Because it allows for the direct determination of HOCs associated with the residual aqueous and experimental surface compartments, the use of radiolabelled HOC analogs is a powerful tool in discriminating among competing sorptive compartments encountered in most SPME fiber calibration methodologies employed to date. PMID:17383665