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1

Absorption coefficient instrument for turbid natural waters  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

2

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

E-print Network

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

Lee, Zhongping

3

Temperature dependence of water vapor absorption coefficients for CO(2) differential absorption lidars.  

PubMed

A temperature correction of water vapor differential absorption coefficients for the CO(2) transition line pairs (10R20, 10R18) and (10R20, 10R22) for temperatures between -0.5 °C and 20 °C is computed, with a reference temperature of 27 °C, from medium-range CO(2) lidar field measurements. The empirical temperature correction, X(T), is fitted with the polynomial X(T) = ?(0) + ?(1) × T + ?(2) × T(2). For the transition line pair (10R20, 10R18) the temperature dependence ranges from 1.62%/°C to 3.47%/°C, and the temperature correction for the transition line pair (10R20, 10R22) ranges from 1.32%/°C to 2.43%/°C. PMID:20861968

Ben-David, A

1993-12-20

4

Variations in the mass-specific absorption coefficient of mineral particles suspended in water  

Microsoft Academic Search

We examined the light-absorption properties of various samples of mineral particles suspended in water, which included pure mineral species (quartz, calcite, illite, kaolinite, and montmorillonite) and natural particulate assem- blages such as desert dust originating from different locations in the Sahara. The absorption coefficient was measured in the spectral region from ultraviolet (UV) to near-infrared on particle suspensions, using a

Marcel Babin; Dariusz Stramski

2004-01-01

5

IR Absorption Coefficients for the Quantification of Water in Majoritic Garnet  

NASA Astrophysics Data System (ADS)

Majoritic garnet, Mg3(Fe,Al,Si)2(SiO4)3, plays an important role in the Earth's transition zone. So far, no independently determined IR absorption coefficient was reported for majoritic garnet, but the knowledge of its absolute water content is essential for modeling the Earth's deep water cycle. Mineral specific absorption coefficients for the quantification of water with IR spectroscopy are required since it has been shown that general linear IR calibrations do not hold for a variety of minerals in which water is not stoichiometrically incorporated but as hydroxyl point defects. In the present work we analyze a series of synthetic majorite single-crystals to provide absorption coefficients for IR spectroscopy. Majorite single-crystals with varying Fe-, Mg-, Al, Cr- and OH contents were synthesized at 18 GPa and 1800 K in a multi-anvil press. Single-crystals (50-500 ?m in size) were characterized using X-ray diffraction, microprobe analysis, IR and Moessbauer spectroscopy. Mineral specific absorption coefficients were calculated from independently determined water contents from secondary ion mass spectrometry. Unpolarized IR spectra of majorite show broad absorption features in the OH region with band maxima at ~3200, 3400, 3575 and 3625 cm-1. The absorption maxima of the OH bands are shifted depending on the composition of the samples. Here we present a mineral specific IR calibration for the quantification of water in majorite and discuss its dependency on compositional changes.

Thomas, S.; Wilson, K.; Koch-Mueller, M.; Jacobsen, S. D.; Hauri, E. H.

2013-12-01

6

Stopping-power and mass energy-absorption coefficient ratios for Solid Water  

Microsoft Academic Search

The AAPM Task Group 21 protocol provides tables of ratios of average restricted stopping powers and ratios of mean energy-absorption coefficients for different materials. These values were based on the work of Cunningham and Schulz. We have calculated these quantities for Solid Water (manufactured by RMI), using the same x-ray spectra and method as that used by Cunningham and Schulz.

Anthony K. Ho; B. R. Paliwal

1986-01-01

7

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

PubMed Central

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

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

2012-01-01

8

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

NASA Technical Reports Server (NTRS)

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.

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

9

Converting Sabine absorption coefficients to random incidence absorption coefficients.  

PubMed

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

Jeong, Cheol-Ho

2013-06-01

10

Irradiance Inversion Algorithm for Estimating the Absorption and Backscattering Coefficients of Natural Waters: Raman-Scattering Effects  

NASA Astrophysics Data System (ADS)

We modify an algorithm for retrieving the absorption ( a ) and backscattering ( b b ) coefficient profiles in natural waters by inverting profiles of downwelling and upwelling irradiance so as to include the presence of Raman scattering. For a given wavelength of interest, , the light field at the appropriate Raman excitation wavelength e is first inverted to obtain the Raman source function at . Starting from estimates of the inherent optical properties at , the contribution to the irradiances at from Raman scattering is then estimated and subtracted from the total irradiances to obtain the elastically scattered irradiances. We then inverted the elastically scattered irradiances to find new estimates of a and b b using our original method Appl. Opt. 37, 3886 (1998) . The algorithm then operates iteratively: The new estimates are used with the Raman source function to derive a new estimate of the Raman contribution, etc. Sample results are provided that demonstrate the working of the algorithm and show that the absorption and scattering coefficients can be retrieved with accuracies similar to those in the absence of Raman scattering down to depths at which the light field is significantly perturbed by it, e.g., with 90% of the upwelling light field originating from Raman scattering.

Boynton, G. Chris; Gordon, Howard R.

2000-06-01

11

Mineral Specific IR Molar Absorption Coefficients for Routine Water Determination in Olivine, SiO2 polymorphs and Garnet  

NASA Astrophysics Data System (ADS)

Conventionally applied Infrared (IR) calibrations [1, 2] for quantitative water analyses in solids are established on hydrous minerals and glasses with several wt% water. These calibrations are based on a negative correlation between the IR molar absorption coefficient (?) for water and the mean wavenumber of the corresponding OH pattern. The correlation reflects the dependence of the OH band position on the appropriate O- H...O distances and thereby the magnitude of the dipole momentum which is proportional to the band intensity. However, it has been observed that these calibrations can not be adopted to nominally anhydrous minerals (NAMs) [3].To study the potential dependence of ? on structure and chemistry in NAMs we synthesized olivine and SiO2 polymorphs with specific isolated hydroxyl point defects, e.g. quartz, coesite and stishovite with B3++H+=Si4+ and/or Al3++H+=Si4+ substitutions. Experiments were performed with water in excess in piston cylinder and multi-anvil presses. Single crystal IR spectra demonstrate that we successfully managed to seperate generally complex OH patterns as e.g. observed in natural quartz and synthetic coesite. We quantified sample water contents of both natural samples and our run products by applying proton-proton-scattering [4], confocal microRaman spectroscopy [5] and Secondary Ion mass spectrometry. Resulting water concentrations were used to calculate new mineral specific ?s. For olivine with the mean wavenumber of 3517 cm-1 we determined an ? value of 41,000±5,000 lmol-1H2Ocm-2. Quantification of olivine with the mean wavenumber of 3550 cm-1 in contrast resulted in an ? value of 47,000±1,000 lmol-1H2Ocm-2. Taking into account previous studies [6, 7] there is evidence to suggest a linear wavenumber dependent correlation for olivine, where ? increases with decreasing wavenumber. In case of the SiO2 system it turns out that the magnitude of ? within one structure type is independent of the liable OH point defect and therewith the wavenumber of the observed band position. Consequently, one single mean ? of 68,000±5,000 lmol-1H2Ocm-2 could be determined for a suite of quartz samples with varying OH point defects. In contrast, ? varies with the structure itself. For polymorphic coesite we calculated a different ? of 214,000±8,000 lmol-1H2O}cm-2, that is in good agreement with earlier established data [8]. Quantification data of stishovite resulted in an even higher value of ?=867,000±29,000 lmol-1H2Ocm-2, similar to that determined by [9]. First data on natural garnet give an ? value of 40,000±2,000 lmol-1H2Ocm-2, that confirms prior suggested values [10]. Our results demonstrate that not using mineral specific calibrations for quantitative water analyses in NAMs leads to overestimation of sample water concentrations, that are required for modelling the earth's deep water cycle. [1]Paterson, M. S. (1982), Bull. Min., 105, 20-29. [2]Libowitzky, E., Rossman, G. R. (1997), Am. Min., 82, 1111- 1115. [3]Rossman, G. R. (2006), Rev. Mineral., 62, 1-28. [4]Reichart et al. (2004), Science, 306, 1537-1540. [5]Thomas et al. (2006), Am. Min., 91, 467-470. [6]Bell et al. (2003), JGR, 108, (B2), 2105-2113. [7]Koch-Mueller et al. (2006), PCM, 33, 276-287. [8]Koch-Mueller et al. (2001), PCM, 28, 693-705. [9]Pawley et al. (1993), Science, 261, 1024-1026. [10]Maldener et al. (2003), PCM, 30, 337-344.

Thomas, S.; Koch-Mueller, M.; Reichart, P.; Rhede, D.; Thomas, R.

2007-12-01

12

Prediction of absorption coefficients by pulsed laser induced photoacoustic measurements.  

PubMed

In the current study, a pulsed laser induced photoacoustic spectroscopy setup was designed and developed, aiming its application in clinical diagnostics. The setup was optimized with carbon black samples in water and with various tryptophan concentrations at 281nm excitations. The sensitivity of the setup was estimated by determining minimum detectable concentration of tryptophan in water at the same excitation, and was found to be 0.035mM. The photoacoustic experiments were also performed with various tryptophan concentrations at 281nm excitation for predicting optical absorption coefficients in them and for comparing the outcomes with the spectrophotometrically-determined absorption coefficients for the same samples. Absorption coefficients for a few serum samples, obtained from some healthy female volunteers, were also determined through photoacoustic and spectrophotometric measurements at the same excitations, which showed good agreement between them, indicating its clinical implications. PMID:24632160

Priya, Mallika; Satish Rao, B S; Ray, Satadru; Mahato, K K

2014-06-01

13

Prediction of absorption coefficients by pulsed laser induced photoacoustic measurements  

NASA Astrophysics Data System (ADS)

In the current study, a pulsed laser induced photoacoustic spectroscopy setup was designed and developed, aiming its application in clinical diagnostics. The setup was optimized with carbon black samples in water and with various tryptophan concentrations at 281 nm excitations. The sensitivity of the setup was estimated by determining minimum detectable concentration of tryptophan in water at the same excitation, and was found to be 0.035 mM. The photoacoustic experiments were also performed with various tryptophan concentrations at 281 nm excitation for predicting optical absorption coefficients in them and for comparing the outcomes with the spectrophotometrically-determined absorption coefficients for the same samples. Absorption coefficients for a few serum samples, obtained from some healthy female volunteers, were also determined through photoacoustic and spectrophotometric measurements at the same excitations, which showed good agreement between them, indicating its clinical implications.

Priya, Mallika; Satish Rao, B. S.; Ray, Satadru; Mahato, K. K.

2014-06-01

14

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

EPA Science Inventory

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

15

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

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

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

2011-01-01

16

Atmospheric absorption of terahertz radiation and water vapor continuum effects  

E-print Network

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

Massachusetts at Lowell, University of

17

Does the photon-diffusion coefficient depend on absorption?  

E-print Network

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

Boas, David

18

Absorption coefficient of zinc selenide grown from the melt  

SciTech Connect

The authors study the absorption coefficient in a series of non-transparent set-ups, which closely resemble the schematic diagram presented. The measurement cells were in air. Temperature was measured by thermocouple sensors, whose contacts with the zinc selenide crystals were screened from the light scattered from the volume of the sample. A continuous CO laser was used as the light source. The absorption coefficient (beta) of zinc selenide single crystals grown from the melt increases with contamination by metallic impurities, among which copper appears to have the greatest effect on beta. The magnitude of absorption coefficient is, generally, not related to the measured transmission and must be determined independently.

Kulakov, M.P.; Fadeev, A.V.; Ivanenko, S.G.; Khasanov, I.S.; Ryazanova, N.D.

1986-02-01

19

Analyzing Water's Optical Absorption  

NASA Technical Reports Server (NTRS)

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.

2002-01-01

20

Sublimation Coefficient of Water Ice  

NASA Astrophysics Data System (ADS)

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.

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

1999-09-01

21

Continuum Absorption Coefficient of Atoms and Ions  

NASA Technical Reports Server (NTRS)

The rate of heat transfer to the heat shield of a Jupiter probe has been estimated to be one order of magnitude higher than any previously experienced in an outer space exploration program. More than one-third of this heat load is due to an emission of continuum radiation from atoms and ions. The existing computer code for calculating the continuum contribution to the total load utilizes a modified version of Biberman's approximate method. The continuum radiation absorption cross sections of a C - H - O - N ablation system were examined in detail. The present computer code was evaluated and updated by being compared with available exact and approximate calculations and correlations of experimental data. A detailed calculation procedure, which can be applied to other atomic species, is presented. The approximate correlations can be made to agree with the available exact and experimental data.

Armaly, B. F.

1979-01-01

22

Two photon absorption coefficients and processing parameters for photoresists  

Microsoft Academic Search

The two photon absorption (TPA) process is currently used to write high resolution microstructures for a variety of applications.\\u000a Key parameters required to predict the final structure formation for this process are experimentally determined and reported\\u000a in this article for two commercially available resists, Ormocore and SU-8. The measured TPA coefficients measured at 800 nm\\u000a for Ormocore and SU-8 are 27 ? 6

Zahidur R. Chowdhury; Robert Fedosejevs

2008-01-01

23

Photoacoustic determination of small optical absorption coefficients: extended theory.  

PubMed

Photoacoustic measurement of small absorption coefficients provides an important alternative to standard techniques. The theoretical basis for such measurements is extended to include the effects of thermally generated mechanical motion of the sample, by incorporating the thermoelastic equations for an isotropicm solid in a cylindrical configuration. Sample calculations show that this thermoacoustic effect may dominate the photoacoustic signal for certain modulation frequencies and beam configurations. PMID:20212851

Alan McDonald, F

1979-05-01

24

Optimization of the acoustic absorption coefficients of certain functional absorbents  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

25

Absorption of water and lubricating oils into porous nylon  

NASA Technical Reports Server (NTRS)

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

Bertrand, P. A.

1995-01-01

26

DETERMINATION OF OCTANOL/WATER DISTRIBUTION COEFFICIENTS, WATER SOLUBILITIES, AND SEDIMENT/WATER PARTITION COEFFICIENTS FOR HYDROPHOBIC ORGANIC POLLUTANTS  

EPA Science Inventory

Octanol/water distribution coefficients, water solubilities, and sediment/water partition coefficients are basic to any assessment of transport or dispersion of organic pollutants. In addition, these determinations are prerequisites for many chemical or biological process studies...

27

Measurements of the absorption coefficient of stratospheric aerosols  

NASA Technical Reports Server (NTRS)

The absorption coefficients of stratospheric aerosols are measured using a variation on the integrating plate method. The technique is based on the decrease in the transparency of a substrate when an absorbing aerosol is deposited on it. A Lambert scatterer is placed behind the substrate to integrate forward scattered light and minimize the effect of scattering on the measurement. The low pressure in the stratosphere is used for the direct impaction of particles onto a narrow strip of opal glass. The eight samples collected had a median value of 4 x 10 to the -9th m with an uncertainty of + or - 5 x 10 to the -9th m. If this absorption is due to graphitic carbon, then its concentration is estimated at about 0.4 ng/cu m, or about 0.25% of the total aerosol mass concentration. Estimates of the aerosol scattering coefficients based on satellite extinction inversions result in an aerosol single-scattering albedo in the range of 0.96-1.0.

Ogren, J. A.; Ahlquist, N. C.; Clarke, A. D.; Charlson, R. J.

1981-01-01

28

Measuring high spectral resolution specific absorption coefficients for use with hyperspectral imagery  

SciTech Connect

A portable, long path length (50 cm), flow through, absorption tube system is utilized to obtain in-situ specific absorption coefficients from various water environments consisting of both clear and turbid water conditions from an underway ship or vessel. The high spectral resolution absorption signatures can be obtained and correlated with measured water quality parameters along a ship track. The long path cuvette system is capable of measuring important water quality parameters such as chlorophyll-a, seston or total suspended matter, tannins, humics, fulvic acids, or dissolved organic matter (dissolved organic carbon, DOC). The various concentrations of these substances can be determined and correlated with laboratory measurements using the double inflection ratio (DIR) of the spectra based upon derivative spectroscopy. The DIR is determined for all of the possible combinations of the bands ranging from 362-1115 nm using 252 channels, as described previously by Bostater. The information gathered from this system can be utilized in conjunction with hyperspectral imagery that allows one to relate reflectance and absorption to water quality of a particular environment. A comparison is made between absorption signatures and reflectance obtained from the Banana River, Florida.

Keller, M.; Bostater, C. [Florida Institute of Technology, Melbourne, FL (United States)

1997-06-01

29

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

Microsoft Academic Search

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

Annick Bricaud; Marcel Babin; André Morel; Hervé Claustre

1995-01-01

30

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

Microsoft Academic Search

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

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

1999-01-01

31

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

NASA Astrophysics Data System (ADS)

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.

Yáñez M., J.

2011-10-01

32

Water sorption and diffusion coefficient through an experimental dental resin.  

PubMed

Polymeric composites have been widely used as dental restorative materials. A fundamental knowledge and understanding of the behavior of these materials in the oral cavity is essential to improve their properties and performance. In this paper we computed the data set of water absorption through an experimental dental resin blend using specimen discs of different thicknesses to estimate the diffusion coefficient. The resins were produced using Bisphenol A glycol dimethacrylate, Bisphenol A ethoxylated dimethacrylate and Triethylene glycol dimethacrylate monomers. The water sorption test method was based on International Standard ISO 4049 "Dentistry-Polymer-based filling materials". Results show a diffusion coefficient around 6.38 x 10(-8) cm(2)/s, within a variance of 0.01%, which is in good agreement with the values reported in the literature and represents a very suitable value. PMID:19693655

Costella, A M; Trochmann, J L; Oliveira, W S

2010-01-01

33

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

34

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

35

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

PubMed

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

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

2015-01-01

36

Synoptic water clarity assessment in the Florida Keys using diffuse attenuation coefficient estimated from Landsat imagery  

Microsoft Academic Search

The diffuse attenuation coefficient, K (m–1), is a measure of the effective attenuation of light in the water column. It characterizes water clarity and is used as a\\u000a proxy for water quality. Mapping of shallow water benthic habitats using optical means, including daytime visible satellite\\u000a imagery, requires knowledge of K to correct for water column effects such as light absorption

D. Palandro; C. Hu; S. Andréfouët; F. E. Muller-Karger

37

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

PubMed

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

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

2014-08-01

38

A method for precomputing effective absorption coefficients from satellite measurements of backscattered UV radiation  

NASA Astrophysics Data System (ADS)

This paper presents a method for computing the effective absorption coefficients for ozone and Rayleigh scattering from satellite measurements of backscattered UV solar radiation. Values of the effective absorption coefficients for ozone and Rayleigh scattering were calculated for polar-zone summer, moderate-zone winter, moderate-zone summer, and the tropics for 12 different wavelength channels. Using these coefficients, the calculations of solar UV radiation (backscattered by the terrestrial atmosphere within the ozone absorption band and measured with SBUV/TOMS instruments) are reduced to calculations of the intensity of monochromatic radiation.

Ishov, A. G.; Kozina, T. V.

1990-10-01

39

Absorption Coefficient Imaging by Near-Field Scanning Optical Microscopy in Bacteria  

NASA Astrophysics Data System (ADS)

We present a method for obtaining a position-dependent absorption coefficient from near-field scanning optical transmission microscopy. We show that the optical transmission intensity can be combined with the topography, resulting into an absorption coefficient that simplifies the analysis of different materials within a sample. The method is tested with the dye rhodamine 6G, and we show some analysis in biological samples such as bacteria Klebsiella pneumoniae and Pseudomonas aeruginosa . The calculated absorption coefficient images show important details of the bacteria, in particular for P. aeruginosa , in which membrane vesicles are clearly seen.

de Paula, Ana M.; Chaves, Claudilene R.; Silva, Haroldo B.; Weber, Gerald

2003-06-01

40

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

PubMed

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

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

2015-03-01

41

Absorption coefficients of dental enamel in the infrared: a solution to a seemingly straightforward problem  

NASA Astrophysics Data System (ADS)

Infrared lasers have been investigated for the modification and ablation of dental hard tissue. Understanding the laser- tissue interaction relies on accurate determination of the optical properties of the tissue. Biological tissues absorb strongly in the infrared region of the spectrum at wavelengths resonant with vibrational absorption bands. In these regions scattering is negligible, therefore only the absorption coefficient and the reflectance are necessary to describe the laser energy deposition in the tissue. Measurement of absorption coefficients is a seemingly simple problem that presents many difficulties when a brittle material such as dental enamel is highly absorbing in the spectral region of interest. Disintegration of dental enamel ensues as a result of fracture before the sample is thin enough to allow direct transmission experiments to determine absorption coefficients at highly absorbing wavelengths (9.3 and 9.6 micrometer). Time resolved radiometric measurements combined with computer modeling of heat deposition and redistribution was used to estimate the absorption coefficient of enamel at various wavelengths in the infrared. This technique allows determination of absorption coefficients in regions not accessible to direct transmission measurements. Problems with the radiometric method and solutions to those problems are presented. The absorption coefficient at 9.6 micrometer was determined to be 5000 cm-1 plus or minus 1000 cm-1.

Zuerlein, Michael J.; Fried, Daniel; Seka, Wolf D.; Featherstone, John D. B.

1998-04-01

42

Relations with phytoplankton distribution and spectral absorption coefficients in the equatorial Pacific  

NASA Astrophysics Data System (ADS)

Small size phytoplankton are dominated in the western and central equatorial Pacific. Our study of HPLC measurements, size fractions of chlorophyll (alpha) and flow cytometric measurements indicate that phytoplankton communities in the equatorial Pacific are dominated by prokaryotic picophytoplankton with Prochlorococcus and Synechococcus, and small size autotrophic eukaryotes. Phytoplankton populations and the distribution were showed to differ from oligotrophic warm water region of the western equatorial Pacific and mesotrophic upwelling region of the central equatorial Pacific. In the oligotrophic region, phytoplankton distribution forms maximum layer around the nitracline. Prochlorococcus is most abundant in there. In the mesotrophic region, chlorophyll maximum layer is not found clearly. The population of autotrophic eukaryotes represented as prymnesiophytes were increased in there. Specific spectral absorption coefficients of phytoplankton [(alpha) *ph((lambda) )] were measured throughout the euphotic zone in the two different regions. The (alpha) *ph((lambda) ) were also reconstructed from HPLC results as the total of specific spectral absorption coefficients of chlorophyll (alpha) [(alpha) *chla((lambda) )], chlorophyll b [(alpha) *chlb((lambda) )], chlorophyll c [(alpha) *chlc((lambda) )], photosynthetically active carotenoids [(alpha) *psc((lambda) )] and photoprotective carotenoids [(alpha) *ppc((lambda) )]. Reconstructed (alpha) *ph((lambda) ) were compared with measured (alpha) *ph((lambda) ). Reconstructed (alpha) *ph((lambda) ) were overestimated at the field of (alpha) *psc((lambda) ), especially in the mesotrophic region. The (alpha) *psc((lambda) ) were considered as high contribution of prymnesiophytes. It was assumed that the package effect of prymnesiophytes was a cause of the overestimate of reconstructed (alpha) *ph((lambda) ).

Matsumoto, Kazuhiko; Kawano, Takeshi; Okano, Hirofumi; Asanuma, Ichio

2001-01-01

43

Intersubband optical absorption coefficients and refractive index changes in modulation-doped asymmetric double quantum well  

NASA Astrophysics Data System (ADS)

The linear and the third-order nonlinear optical absorption coefficients and refractive index changes in a modulation-doped asymmetric double quantum well are studied theoretically. The electron energy levels and the envelope wave functions in this structure are calculated by the Schrödinger and Poisson equations self-consistently in the effective mass approximation. The analytical expressions of optical properties are obtained by using the compact density-matrix approach. In this regard, the linear, nonlinear and total intersubband absorption coefficients and refractive index changes are investigated as a function of right-well width ( Lw2) of asymmetric double quantum well. Our results show that the total absorption coefficients and refractive index changes shift toward higher energies as the right-well width decreases. In addition, the total optical absorption coefficients and refractive index changes is strongly dependent on the incident optical intensity.

Ungan, F.; Kasapoglu, E.; Sokmen, I.

2011-10-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

45

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

46

Estimating the sound absorption coefficients of perforated wooden panels by using artificial neural networks  

Microsoft Academic Search

Developing efficient sound absorption materials is a relevant topic for large scale structures such as gymnasiums, shopping malls, airports and stations. This study employs artificial neural network (ANN) algorithm to estimate the sound absorption coefficients of different perforated wooden panels with various setting combinations including perforation percentage, backing material and thickness. The training data sets are built by carrying out

Min-Der Lin; Kang-Ting Tsai; Bo-Sheng Su

2009-01-01

47

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

ERIC Educational Resources Information Center

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

Ouseph, P. J.; And Others

1982-01-01

48

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

ERIC Educational Resources Information Center

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.

Cordon, Gabriela B.; Lagorio, M. Gabriela

2007-01-01

49

Attenuation coefficients for water quality trading.  

PubMed

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

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

2014-06-17

50

Bottom Extreme-Ultraviolet-Sensitive Coating for Evaluation of the Absorption Coefficient of Ultrathin Film  

NASA Astrophysics Data System (ADS)

A bottom extreme-ultraviolet-sensitive coating (BESC) for evaluation of the absorption coefficients of ultrathin films such as extreme ultraviolet (EUV) resists was developed. This coating consists of a polymer, crosslinker, acid generator, and acid-responsive chromic dye and is formed by a conventional spin-coating method. By heating the film after spin-coating, a crosslinking reaction is induced and the coating becomes insoluble. A typical resist solution can be spin-coated on a substrate covered with the coating film. The evaluation of the linear absorption coefficients of polymer films was demonstrated by measuring the EUV absorption of BESC substrates on which various polymers were spin-coated.

Hijikata, Hayato; Kozawa, Takahiro; Tagawa, Seiichi; Takei, Satoshi

2009-06-01

51

[Characteristics of optical absorption coefficients and their differences in typical seasons in Lake Qiandaohu].  

PubMed

Absorption characteristics of total suspended particulate, phytoplankton and tripton in Lake Qiandaohu are presented based on the in situ data collected in winter (from December 2012 to February 2013) and summer (from July to August 2013). The mean values of total suspended particle absorption coefficients at 440 nm [a(p) (440)] in winter and summer are (0.20 +/- 0.07) m(-1) and (0.24 +/- 0.17) m(-1). Correspondingly, the mean values of a(p) (675) are (0.07 +/- 0.02) m(-1) and (0.10 +/- 0.07) m(-1). In winter the absorption spectra of total suspended particulate matters can be divided into two cases: the absorption spectra are similar to those of phytoplankton in the northwest lake and to those of tripton in other lake regions. In summer, the absorption spectra of total suspended particles are similar to those of phytoplankton from 400 nm to 700 nm. The mean values of phytoplankton absorption coefficients at 440 nm [a(ph) (440)] are (0.10 +/- 0.03) m(-1) in winter, and (0.17 +/- 0.14) m(-1) in summer. Accordingly, the mean values of a(ph) (675) are (0.05 +/- 0.02) m(-1) and (0.08 +/- 0.07) m(-1). The mean values of Chlorophyll-specific absorption coefficients (by the concentration of Chla) at440 nm a(*)(ph)(440) are (0.045 +/- 0.010) m2 x mg(-1) in winter and (0.039 +/- 0.013) m2 x mg(-1) in summer. At the same time, the mean values of a(*)(ph) (675) are (0.022 +/- 0.004) m2 x mg(-1) and (0.019 +/- 0.005) m2 x mg(-1). Significantly linear correlations are found between phytoplankton absorption coefficients and chlorophyll a concentration, trophic level index (TLI). Chlorophyll-specific absorption coefficients vary with the chlorophyll a concentrations following a power function. The tripton absorption coefficients exponentially decrease from 400 nm to 700 nm. The correlation between tripton absorption coefficients and inorganic particles is significant in winter, whereas, the correlation between tripton absorption coefficients and the concentrations of total suspended particles and organic particles are significant in summer. PMID:25244834

Wang, Ming-Zhu; Zhang, Yun-Lin; Shi, Kun; Gao, Yun; Liu, Gang; Jiang, Hao

2014-07-01

52

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

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

53

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

NASA Astrophysics Data System (ADS)

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.

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

1996-07-01

54

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

PubMed

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

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

2014-07-01

55

Expression of optical diffusion coefficient in high-absorption turbid media  

NASA Astrophysics Data System (ADS)

The optical diffusion coefficient in a homogeneous turbid medium with high absorption was determined by steady-state measurements of the light transmission under the infinite-boundary condition. The intensity of the transmission was well described by the solution of the optical diffusion equation. Moreover, the optical diffusion coefficient D was given by a constant, , where is the reduced scattering coefficient, up to the absorption coefficient of about . These results mean that attenuation by absorption only contributes to exponential attenuation along the optical path defined by the scattering coefficient and geometry of the system even in high-absorption turbid media such as the pathological living tissues of bleeding or haematoma.

Nakai, T.; Nishimura, G.; Yamamoto, K.; Tamura, M.

1997-12-01

56

Measurements of NH3 absorption coefficients with a C-13/O-16/2 laser  

NASA Technical Reports Server (NTRS)

Measurements of NH3 absorption coefficients are presented for several transitions of a C-13(O-16)2 laser for small concentrations of NH3(p less than 1 torr) for absorption lines broadened to 1 atm with N2. NH3 absorption coefficients were determined for laser transitions R(8)(920.2194 wavelengths/cm) to R(28)(933.8808 wavelengths/cm) of the 00 1 - (10 0,02 0)I band. The strongest absorption coefficient K = 36.09 + or - 1.43 per (atm-cm) was measured for the R(18) transition for the NH3 line, aQ(6,6), and is larger than has been found in any previous measurements with a CO2 laser. The dependence of K on total pressure was also obtained for select transitions, and the frequency separation between the R(18) laser transition and the neighboring NH3 line aQ(6,6) was determined to be 550 + or - 50 MHz. These results are significant for long path absorption monitoring of NH3 with CO2 lasers since the path length can be reduced by approximately 40% and for heterodyne detection of NH3 since the relative position of the laser transition to the NH3 absorption line is well within the bandpass of Hg-Cd-Te photomixers.

Allario, F.; Seals, R. K., Jr.

1975-01-01

57

Measurement of the two-photon absorption coefficient of semiconductor nanocrystals by using tunable femtosecond pulses  

NASA Astrophysics Data System (ADS)

By using femtosecond pulses from traveling-wave parametric generation we have accurately measured the absolute value and the frequency dispersion of the two-photon absorption coefficient of semiconductor nanocrystals embedded in a glass matrix. Comparison is made with bulk semiconductors.

Banfi, G. P.; Degiorgio, V.; Fortusini, D.; Bellini, M.

1996-09-01

58

Absorption coefficients of solid NH3 from 50 to 7000 per cm  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

59

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

Microsoft Academic Search

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

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

1995-01-01

60

Measurement of Aerosol Absorption Coefficient from Teflon Filters Using Integrating Plate and Integrating Sphere Techniques  

Microsoft Academic Search

Optical transmission of aerosol samples collected on Teflon filters measured by the integrating plate method (IPM) has been used as a means of determining the aerosol absorption coefficient, b , by the Air Quality Group at Crocker Nuclear Lab for over 9 years. The results of an intensive quality assurance program, using an integrating sphere photometer configured for measurement of

Dave Campbell; Scott Copeland; Thomas Cahill

1995-01-01

61

Method to derive ocean absorption coefficients from remote-sensing reflectance  

E-print Network

Method to derive ocean absorption coefficients from remote-sensing reflectance Z. P. Lee, K. L for possible Sun glint and reflected cloud light from the uneven sea surface.8 Note that wavelength dependency has been suppressed for brevity. Z. P. Lee, K. L. Carder, and T. G. Peacock are with the Department

Lee, Zhongping

62

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)

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.

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

2014-11-01

63

Selection of stopping-power and mass energy-absorption coefficient ratios for high-energy x-ray dosimetry  

Microsoft Academic Search

A method for the selection of average stopping-power (L-bar\\/rho)\\/sup med\\/\\/sub air\\/ and energy-absorption coefficient ( mu-bar\\/sub en\\/\\/rho)\\/sup med\\/\\/sub air\\/ ratios has been developed. The quality of the x-ray beam is characterized by the ratio of ionization chamber readings at depths of 20 and 10 cm in water (TMR)²°ââ. For convenience, a relationship is established between experimental (TMR)²°ââ and the nominal

John R. Cunningham; R. J. Schulz

1984-01-01

64

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

NASA Astrophysics Data System (ADS)

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

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

65

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

SciTech Connect

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.

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

66

Atmospheric absorption of terahertz radiation and water vapor continuum effects  

E-print Network

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

Massachusetts at Lowell, University of

67

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

PubMed Central

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

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

1995-01-01

68

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

Microsoft Academic Search

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 -

P. Artursson; J. Karlsson

1991-01-01

69

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

SciTech Connect

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.

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

1980-07-01

70

Biochimica et Biophysica Acta 902 (1987) 183-192 183 Effects of divalent cations on the ultrasonic absorption coefficient  

E-print Network

on the ultrasonic absorption coefficient of negatively charged liposomes (LUV) near their phase transition The ultrasonic absorption coefficient per wavelength (a~), as a function of temperature and frequency (a~)~ at the phase transition temperature (tin) of the phospholipids in the bilayer, at an ultrasonic

Illinois at Urbana-Champaign, University of

71

Humidity dependence of the atmospheric absorption coefficient in the transparency windows centered at 0.88 and 0.73 mm  

NASA Astrophysics Data System (ADS)

The dependence of the absorption coefficient of atmospheric water vapor on absolute air humidity, in the 11.1-12.0 and 13.2-14.3/cm spectral intervals, is investigated by means of multipass vacuum cell radiospectrometry. The humidity range in question lies between 3 and 23 g/cu m, at 140 m of the optical path. Elements of the absorption coefficient which linearly and quadratically depend on humidity have been separately defined on the basis of the experimental data, and the centers of the atmospheric windows are obtained for 306 K and a dry air pressure of 735 Torr.

Furashov, N. I.; Katkov, V. Iu.

1985-08-01

72

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

Microsoft Academic Search

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.

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

2003-01-01

73

Simultaneous measurement of thermal diffusivity and optical absorption coefficient using photothermal radiometry. II Multilayered solids  

NASA Astrophysics Data System (ADS)

The aim of this work is to analyze the ability of modulated photothermal radiometry to retrieve the thermal diffusivity and the optical absorption coefficient of layered materials simultaneously. First, we extend the thermal quadrupole method to calculate the surface temperature of semitransparent multilayered materials. Then, this matrix method is used to evaluate the influence of heat losses by convection and radiation, the influence of the use of thin paint layers on the accuracy of thermal diffusivity measurements, and the effect of lateral heat diffusion due to the use of Gaussian laser beams. Finally, we apply the quadrupole method to retrieve (a) the thermal contact resistance in glass stacks and (b) the thermal diffusivity and optical absorption coefficient depth profiles in heterogeneous materials with continuously varying physical properties, as is the case of functionally graded materials and partially cured dental resins.

Salazar, Agustín; Fuente, Raquel; Apiñaniz, Estibaliz; Mendioroz, Arantza; Celorrio, R.

2011-08-01

74

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

PubMed

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

Majaron, Boris; Milanic, Matija

2008-01-01

75

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

76

Determination of absorption coefficient by digital holographic measurement of optical excitation.  

PubMed

Digital holographic microscopy produces quantitative phase analysis of a specimen with excellent optical precision. In this study, this imaging method has been used to observe and measure induced thermal lensing by optical excitation. Previous studies have derived these phase shifts from intensity profiles for the determination of photothermal properties of very transparent materials. We have measured physical observables and determined the absorption coefficients of methanol and ethanol with improved precision and accuracy over traditional thermal lens spectroscopy methods. PMID:21509057

Clark, David C; Kim, Myung K

2011-04-20

77

Two-photon interband absorption coefficients in tungstate and molybdate crystals  

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

79

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

PubMed

Backscatter factors, B, and mass energy-absorption coefficient ratios, (?(en)/?)(w, air), for the determination of the surface dose in diagnostic radiology were calculated using Monte Carlo simulations. The main purpose was to extend the range of available data to qualities used in modern x-ray techniques, particularly for interventional radiology. A comprehensive database for mono-energetic photons between 4 and 150 keV and different field sizes was created for a 15 cm thick water phantom. Backscattered spectra were calculated with the PENELOPE Monte Carlo system, scoring track-length fluence differential in energy with negligible statistical uncertainty; using the Monte Carlo computed spectra, B factors and (?(en)/?)(w, air) were then calculated numerically for each energy. Weighted averaging procedures were subsequently used to convolve incident clinical spectra with mono-energetic data. The method was benchmarked against full Monte Carlo calculations of incident clinical spectra obtaining differences within 0.3-0.6%. The technique used enables the calculation of B and (?(en)/?)(w, air) for any incident spectrum without further time-consuming Monte Carlo simulations. The adequacy of the extended dosimetry data to a broader range of clinical qualities than those currently available, while keeping consistency with existing data, was confirmed through detailed comparisons. Mono-energetic and spectra-averaged values were compared with published data, including those in ICRU Report 74 and IAEA TRS-457, finding average differences of 0.6%. Results are provided in comprehensive tables appropriated for clinical use. Additional qualities can easily be calculated using a designed GUI interface in conjunction with software to generate incident photon spectra. PMID:22024474

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

2011-11-21

80

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

81

Effects of the absorption coefficient on resonant infrared laser ablation of poly(ethylene glycol)  

NASA Astrophysics Data System (ADS)

We describe experiments on resonant infrared laser ablation of poly(ethylene glycol) (PEG) at two different resonant excitation wavelengths and for different molecular weights of PEG. The two resonant wavelengths correspond to different stretching vibrations of the polymer and have absorption coefficients that differ by roughly an order of magnitude. Ablation via excitation of the O-H terminal group stretching mode at 2.94 ?m, the weaker of the two absorptions, is delayed in time by several microseconds with respect to ablation at 3.47 ?m, the more strongly absorbing C-H stretching mode of the polymer. Time-resolved plume shadowgraphs along with ablation rate measurements for the two modes reveal that the absorption coefficient strongly affects the physical characteristics of the ejecta and plume, as well as the time scale for material removal. Temperature-rise calculations demonstrate that phase explosion is likely the operative mechanism in ablation at the C-H mode, while normal boiling may play a role in material removal at the O-H mode.

Johnson, S. L.; Schriver, K. E.; Haglund, R. F.; Bubb, D. M.

2009-01-01

82

Predicting Soil-Water Partition Coefficients for Cadmium  

E-print Network

when applied to measurements at the natural soil pH because of the competition of protons with Cd and adsorption to components of the soil, processes that are highly pH dependent. For trace metals, adsorptionPredicting Soil-Water Partition Coefficients for Cadmium S U E N - Z O N E L E E Department

Sparks, Donald L.

83

PARTITION COEFFICIENTS FOR METALS IN SURFACE WATER, SOIL, AND WASTE  

EPA Science Inventory

This report presents metal partition coefficients for the surface water pathway and for the source model used in the Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology under development by the U.S. Environmental Protection Agency. Partition ...

84

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

SciTech Connect

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.

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

85

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

PubMed

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

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

2014-12-01

86

Measurement of krypton-85 in water by absorption in polycarbonates  

Microsoft Academic Search

This article describes a method for quantitative measurements of Kr85 in water by absorption in polycarbonates. The method is based on exposure of polycarbonate samples in water and uses the high absorption ability to noble gases of some polycarbonates like Makrofol® and Makrolon® for sampling Kr85 from the water. After the exposure, the radiation emitted from the samples is measured

K. Mitev; D. Pressyanov; I. Dimitrova; S. Georgiev; T. Boshkova; V. Zhivkova

2009-01-01

87

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

PubMed

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

Müller-Trapet, Markus; Vorländer, Michael

2015-01-01

88

Mesure de coefficients d'absorption de plasmas créés par laser nanoseconde  

NASA Astrophysics Data System (ADS)

La mesure des coefficients d'absorption dans les plasmas chauds est particulièrement utile dans le domaine de la fusion par confinement inertiel ainsi que dans divers contextes en astrophysique. Le développement des calculs de physique atomique qui y sont associés repose sur des hypothèses qu'il est nécessaire de vérifier dans la plus large gamme possible de conditions physiques. Nous présentons ici la méthode de mesure et d'analyse employée en nous appuyant sur l'exemple des cibles multicouches nickel/aluminium.

Thais, F.; Chenais-Popovics, C.; Eidmann, K.; Bastiani, S.; Blenski, T.; Gilleron, F.

2005-06-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

90

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

NASA Technical Reports Server (NTRS)

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

Harward, C. N.

1977-01-01

91

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

NASA Astrophysics Data System (ADS)

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

Beran, Pavel

2013-10-01

92

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

E-print Network

Mass-specific light absorption coefficients of natural aquatic particles in the near-infrared in the near-infrared spectral region (NIR; 700­900 nm) of natural suspended particles was investigated is dominated by absorption of dissolved and suspended matter. In the near-infrared spectral region (NIR; 700

93

Spectral variation of the infrared absorption coefficient in pulsed photothermal profiling of biological samples.  

PubMed

Pulsed photothermal radiometry can be used for non-invasive depth profiling of optically scattering samples, including biological tissues such as human skin. Computational reconstruction of the laser-induced temperature profile from recorded radiometric signals is sensitive to the value of the tissue absorption coefficient in the infrared detection band (muIR). While assumed constant in reported reconstruction algorithms, muIR of human skin varies by two orders of magnitude in the commonly used 3-5 microm detection band. We analyse the problem of selecting the effective absorption coefficient value to be used with such algorithms. In a numerical simulation of photothermal profiling we demonstrate that results can be markedly impaired, unless the reconstruction algorithm is augmented by accounting for spectral variation muIR(lambda). Alternatively, narrowing the detection band to 4.5-5 microm reduces the spectral variation muIR(lambda) to a level that permits the use of the simpler, unaugmented algorithm. Implementation of the latter approach for depth profiling of port wine stain birthmarks in vivo is presented and discussed. PMID:12108776

Majaron, Boris; Verkruysse, Wim; Tanenbaum, B Samuel; Milner, Thomas E; Nelson, J Stuart

2002-06-01

94

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

PubMed Central

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

Hirasawa, Takeshi; Kushibiki, Toshihiro; Ishihara, Miya

2015-01-01

95

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

96

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

PubMed Central

An alternative measure of x-ray absorption spectroscopy (XAS) called inverse partial fluorescence yield (IPFY) has recently been developed that is both bulk sensitive and free of saturation effects. Here we show that the angle dependence of IPFY can provide a measure directly proportional to the total x-ray absorption coefficient, µ(E). In contrast, fluorescence yield (FY) and electron yield (EY) spectra are offset and/or distorted from µ(E) by an unknown and difficult to measure amount. Moreover, our measurement can determine µ(E) in absolute units with no free parameters by scaling to µ(E) at the non-resonant emission energy. We demonstrate this technique with measurements on NiO and NdGaO3. Determining µ(E) across edge-steps enables the use of XAS as a non-destructive measure of material composition. In NdGaO3, we also demonstrate the utility of IPFY for insulating samples, where neither EY or FY provide reliable spectra due to sample charging and self-absorption effects, respectively. PMID:22355697

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

2011-01-01

97

The Optical Absorption Coefficient of Bean Seeds Investigated Using Photoacoustic Spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

98

Measurement of the diffusion coefficient of sulfur hexafluoride in water  

Microsoft Academic Search

Sulfur hexafluoride has been widely used in field studies and laboratory experiments to develop a relationship between gas transfer and wind speed. The interpretation of the data from such studies requires the diffusion coefficient of SFâ (D{sub SF6}), which has not previously been measured. In this study, D{sub SF6} has been determined in pure water and in 35%NaCl over a

King. D. B; E. S. Saltzman

1995-01-01

99

Effects of methyl red acidity and UV illumination on absorption coefficient of MR/PVA thin films  

NASA Astrophysics Data System (ADS)

The absorption coefficient spectra of poly(vinyl alcohol), PVA, mixed with methyl red (MR) thin films on glass substrates, prepared by the spin coating method has been investigated using scanning electron microscopy (SEM) and spectroscopic ellipsometry. SEM imaging indicates that the surface of the MR/PVA film is smooth, uniform, and no crack could be observed. Spectroscopic ellipsometry measurements of PVA and MR/PMMA thin films were carried out at three angles of incidence, over the wavelength range 400-800 nm. Optical models were used to obtain the absorption coefficients for the prepared samples. These models include Cauchy formula for the glass substrate and PVA film, Lorentz model with three oscillators for MR layer, and a Bruggeman effective medium approximation for MR/PVA films. Absorption coefficients were found to be in the range 5×10 3-5×10 4 cm -1 with a maximum being at about 475 nm. Changing the absorption coefficient as a function of increasing the pH of MR causes a shift of the absorption band toward higher wavelengths. Our results show that the absorption coefficient of the film decreases upon increasing the UV illumination time.

El-Nasser, H. M.

2011-05-01

100

40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.  

Code of Federal Regulations, 2010 CFR

...coefficient (n-octanol/water), shake flask method. ...TESTING REQUIREMENTS Product Properties Test Guidelines § 799.6755...coefficient (n -octanol/water), shake flask method. ...method, dissociation constant, water solubility, and...

2010-07-01

101

40 CFR 799.6755 - TSCA partition coefficient (n-octanol/water), shake flask method.  

Code of Federal Regulations, 2011 CFR

...coefficient (n-octanol/water), shake flask method. ...TESTING REQUIREMENTS Product Properties Test Guidelines § 799.6755...coefficient (n -octanol/water), shake flask method. ...method, dissociation constant, water solubility, and...

2011-07-01

102

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 ...

103

Effect of water absorption on pollen adhesion.  

PubMed

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

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

2015-03-15

104

Application of two inversion schemes to determine the absorption coefficient distribution in flames  

NASA Astrophysics Data System (ADS)

In this paper, two analytical expressions for the integrated form of the radiative transfer equation are discussed. Reconstructed optical thickness distributions in an axisymmetric medium are compared for benchmark profiles using a new cubic-spline approximation to the Abel integral equation and a tomographic reconstruction technique. Both methods yield equal or more accurate results than all existing models under error-free conditions and under experimental conditions. The schemes are used to reduce the experimental data from laminar jet diffusion flames and to determine the radiative properties of an absorbing-emitting, cylindrically symmetric medium. The advantages and drawbacks of the models in reconstructing the unknown absorption coefficient distributions in flames are discussed.

Chakravarty, S.; Menguc, M. P.; Mackowsky, D. W.; Altenkirch, R. A.

105

Variation of absorption coefficient and determination of critical dose of SU-8 at 365 nm  

SciTech Connect

The absorption coefficient of thick-films of the negative photoresist SU-8 is observed to be time dependent during photolithographic exposure by I-line ultraviolet light ({lambda}=365 nm); varying linearly from 38{+-}1 cm{sup -1} to 49{+-}1 cm{sup -1} for a surface exposure dose of 415 mJ/cm{sup 2}. We develop a general model which enables the exposure dose to be calculated at a given photoresist depth for a given exposure time. We determine the critical exposure dose for the subsequent polymerization of SU-8 having an arbitrary thickness to be 49.4{+-}3.9 mJ cm{sup -2}.

Gaudet, Matthieu; Camart, Jean-Christophe; Buchaillot, Lionel; Arscott, Steve [Institut d'Electronique, de Microelectronique et de Nanotechnologie (IEMN), CNRS UMR8520, ISEN Dept., Avenue Poincare, Cite Scientifique, Villeneuve d'Ascq 59652 (France)

2006-01-09

106

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)

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.

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

2008-01-01

107

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

SciTech Connect

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.

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

1980-12-01

108

Measurement of acoustic absorption coefficient with phase-conjugate ultrasonic waves  

NASA Astrophysics Data System (ADS)

Experimental results on measurements of the acoustic absorption coefficient in test objects that were obtained with two methods, i.e., a standard insert-substitution method and a modification thereof using phase-conjugate waves, are given. Samples of gelatin and biological tissue in vitro (porcine muscle fibers) were used as test objects. Gelatin objects were manufactured that were both homogeneous and with inhomogeneities in the form of a rough surface or inclusions (air bubbles) distributed over the volume. A rough surface leads mainly to phase distortions of a probe beam, while bubble inclusions cause additional field scattering. For all homogeneous samples, both compared methods produce identical results. In the case of inhomogeneous samples including biological tissues, absorption measurement by a standard method may lead to significant errors. It is demonstrated that the use of properties of phase-conjugate waves provides an opportunity to eliminate almost completely the measurement error connected with phase distortions and reduce the error in the case of a medium with scatterers.

Smagin, N. V.; Krutyansky, L. M.; Brysev, A. P.; Bunkin, F. V.

2011-07-01

109

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

SciTech Connect

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.

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

110

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)

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.

Qu, Yonghua; Zhu, Yeqing; Ge, Xiaoli

2014-03-01

111

OCTANOL/WATER PARTITION COEFFICIENTS AND WATER SOLUBILITIES OF PHTHALATE ESTERS  

EPA Science Inventory

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

112

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

NASA Astrophysics Data System (ADS)

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.

Ozturk, Emine; Ozdemir, Yasin

2013-05-01

113

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

114

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

SciTech Connect

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

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

1990-05-01

115

Diffusion coefficients of substituted benzenes at high dilution in water  

SciTech Connect

Among the three basic environmental compartments of soil, water, and air, the latter two form the major abiotic dispersion pathways of chemicals, and in unsaturated soil zones it is the pore water that governs vertical leaching of contaminants to the groundwater by advection and diffusion phenomena. The interdiffusion coefficient D{sub aw} of 6 hydrophobic benzene derivatives (a = chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, bromobenzene, 1,2-dibromobenzene, 1,4-dibromobenzene) in aqueous solution (w) at 250 C is measured at different concentrations below 10{sup {minus}5} solute mole fractions using the Taylor dispersion technique. On the basis of the experimental uncertainty around 4%, a distinct concentration dependence is not recognizable. Analysis of the interdiffusion coefficients with the Stokes-Einstein equation shows greater D{sub aw}{sup {infinity}} values than expected from the limit of a complete solute-solvent contact stick limit, and in addition substance-specific deviations. Chemical engineering correlations for D{sub aq}{sup {infinity}} presently available from the literature yield unsatisfactory results for this class of predominantly hydrophobic compounds.

Gabler, T.; Paschke, A.; Schueuermann, G. [Centre for Environmental Research, Leipzig (Germany). Dept. of Chemical Ecotoxicology] [Centre for Environmental Research, Leipzig (Germany). Dept. of Chemical Ecotoxicology

1996-01-01

116

Emergency membrane contactor based absorption system for ammonia leaks in water treatment plants.  

PubMed

Abstract Because of the suspected health risks of trihalomethanes (THMs), more and more water treatment plants have replaced traditional chlorine disinfection process with chloramines but often without the proper absorption system installed in the case of ammonia leaks in the storage room. A pilot plant membrane absorption system was developed and installed in a water treatment plant for this purpose. Experimentally determined contact angle, surface tension, and corrosion tests indicated that the sulfuric acid was the proper choice as the absorbent for leaking ammonia using polypropylene hollow fiber membrane contactor. Effects of several operating conditions on the mass transfer coefficient, ammonia absorption, and removal efficiency were examined, including the liquid concentration, liquid velocity, and feed gas concentration. Under the operation conditions investigated, the gas absorption efficiency over 99.9% was achieved. This indicated that the designed pilot plant membrane absorption system was effective to absorb the leaking ammonia in the model storage room. The removal rate of the ammonia in the model storage room was also experimentally and theoretically found to be primarily determined by the ammonia suction flow rate from the ammonia storage room to the membrane contactor. The ammonia removal rate of 99.9% was expected to be achieved within 1.3 h at the ammonia gas flow rate of 500 m3/h. The success of the pilot plant membrane absorption system developed in this study illustrated the potential of this technology for ammonia leaks in water treatment plant, also paved the way towards a larger scale application. PMID:19143342

Shao, Jiahui; Fang, Xuliang; He, Yiliang; Jin, Qiang

2008-01-01

117

Optoelectronic properties of Mg{sub 2}Si semiconducting layers with high absorption coefficients  

SciTech Connect

In an attempt to develop a low-cost material for solar cell devices, polycrystalline magnesium silicide (poly-Mg{sub 2}Si) semiconducting layers have been prepared by applying rf magnetron sputtering using a Mg{sub 2}Si target. The optimum substrate temperature for the poly-Mg{sub 2}Si growth was found to be T{sub s} = 200 deg. C; the film deposition at higher temperatures leads to desorption of Mg atoms from the growing surface, while the amorphous phase formation occurs at room temperature. The poly-Mg{sub 2}Si layer deposited at T{sub s} = 200 deg. C shows the (111) preferential orientation with a uniform grain size of {approx}50 nm. The dielectric function of the poly-Mg{sub 2}Si layer has been determined accurately by spectroscopic ellipsometry. From the analysis, quite high absorption coefficients and an indirect gap of 0.77 eV in the poly-Mg{sub 2}Si layer have been confirmed. The above poly-Mg{sub 2}Si layer shows clear photoconductivity and can be applied as a narrow-gap bottom layer in multi-junction solar cell devices.

Kato, Takashi; Sago, Yuichiro; Fujiwara, Hiroyuki [Center of Innovative Photovoltaic Systems (CIPS), Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan)

2011-09-15

118

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

PubMed

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

Majaron, Boris; Milanic, Matija

2007-02-21

119

Simultaneous measurement of thermal diffusivity and optical absorption coefficient using photothermal radiometry. I. Homogeneous solids  

NASA Astrophysics Data System (ADS)

Modulated photothermal radiometry (PTR) has been widely used to measure the thermal diffusivity of bulk materials. The method is based on illuminating the sample with a plane light beam and measuring the infrared emission with an infrared detector. The amplitude and phase of the PTR voltage is recorded as a function of the modulation frequency and then fitted to the theoretical model. In this work, we test the ability of modulated PTR to retrieve simultaneously the thermal diffusivity and the optical absorption coefficient of homogeneous slabs. In order to eliminate the instrumental factor, self-normalization is used, i.e., the ratio of the PTR signal recorded at the rear and front surfaces. The influence of the multiple reflections of the light beam, the heat losses, and the transparency to infrared wavelengths are analyzed. Measurements performed on a wide variety of homogeneous materials, covering the whole range from transparent to opaque, confirm the validity of the method. In Part II of this work, the method is extended to multilayered materials.

Fuente, Raquel; Apiñaniz, Estibaliz; Mendioroz, Arantza; Salazar, Agustín

2011-08-01

120

Effect of absorption parameters on calculation of the dose coefficient: example of classification of industrial uranium compounds.  

PubMed

In the Human Respiratory Tract Model (HRTM) described in ICRP Publication 66, time-dependent dissolution is described by three parameters: the fraction dissolved rapidly, fr, and the rapid and slow dissolution rates sr and ss. The effect of these parameters on the dose coefficient has been studied. A theoretical analysis was carried out to determine the sensitivity of the dose coefficient to variations in the values of these absorption parameters. Experimental values of the absorption parameters and the doses per unit intake (DPUI) were obtained from in vitro dissolution tests, or from in vivo experiments with rats, for five industrial uranium compounds UO2, U3O8, UO4, UF4 and a mixture of uranium oxides. These compounds were classified in terms of absorption types (F, M or S) according to ICRP. The overall result was that the factor which has the greatest influence on the dose coefficient was the slow dissolution rate ss. This was verified experimentally, with a variation of 20% to 55% for the DPUI according to the absorption type of the compound. In contrast, the rapid dissolution rate sr had little effect on the dose coefficient, excepted for Type F compounds. PMID:11487809

Chazel, V; Houpert, P; Paquet, F; Ansoborlo, E

2001-01-01

121

Absorption coefficient of HCl in the region 1400 to 2200 A. [for photodissociation rate in Venus atmosphere  

NASA Technical Reports Server (NTRS)

The results of absorption coefficient measurements of HCl in the region 1400 to 2200 A are reported and compared with those previously published. It is concluded that the present results represent the best compromise of all measurements and should be used for any calculations on the photodissociation rate of HCl in planetary atmospheres.

Inn, E. C. Y.

1975-01-01

122

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

EPA Science Inventory

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

123

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

124

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

NASA Astrophysics Data System (ADS)

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}.

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

1996-05-01

125

Quantitative photoacoustic tomography from boundary pressure measurements: noniterative recovery of optical absorption coefficient from the reconstructed absorbed energy map.  

PubMed

We describe a noniterative method for recovering optical absorption coefficient distribution from the absorbed energy map reconstructed using simulated and noisy boundary pressure measurements. The source reconstruction problem is first solved for the absorbed energy map corresponding to single- and multiple-source illuminations from the side of the imaging plane. It is shown that the absorbed energy map and the absorption coefficient distribution, recovered from the single-source illumination with a large variation in photon flux distribution, have signal-to-noise ratios comparable to those of the reconstructed parameters from a more uniform photon density distribution corresponding to multiple-source illuminations. The absorbed energy map is input as absorption coefficient times photon flux in the time-independent diffusion equation (DE) governing photon transport to recover the photon flux in a single step. The recovered photon flux is used to compute the optical absorption coefficient distribution from the absorbed energy map. In the absence of experimental data, we obtain the boundary measurements through Monte Carlo simulations, and we attempt to address the possible limitations of the DE model in the overall reconstruction procedure. PMID:18758563

Banerjee, Biswanath; Bagchi, Srijeeta; Vasu, Ram Mohan; Roy, Debasish

2008-09-01

126

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...

127

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

128

Studies of Water Absorption Behavior of Plant Fibers at Different Temperatures  

NASA Astrophysics Data System (ADS)

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.

Saikia, Dip

2010-05-01

129

Measurement of the diffusion coefficient of sulfur hexafluoride in water  

SciTech Connect

Sulfur hexafluoride has been widely used in field studies and laboratory experiments to develop a relationship between gas transfer and wind speed. The interpretation of the data from such studies requires the diffusion coefficient of SF{sub 6} (D{sub SF6}), which has not previously been measured. In this study, D{sub SF6} has been determined in pure water and in 35%NaCl over a temperature range of 5-25{degrees}C. The measurements were made using a continuous-flow diffusion cell where SF{sub 6} flows beneath an agar gel membrane while helium flows above the gel. The experimental data for pure water yielded the following equation: D{sub SF6}=0.029 exp ({minus}19.3/RT, where R is the gas constant and T is temperature in kelvins). Measurements of D{sub SF6} in 35% NaCl were not significantly different from the pure water values. On the basis of this data, the authors estimate the Schmidt numbers for seawater over the temperature range 5-25{degrees}C to be Sc=3016.1{minus}172.00t+4.4996t{sup 2}{minus}0.047965t{sup 3}, where t is temperature in degrees Celsius. 31 refs., 3 figs., 2 tabs.

King. D.B.; Saltzman, E.S. [Univ. of Miami, FL (United States)] [Univ. of Miami, FL (United States)

1995-04-15

130

Absorptive removal of biomass tar using water and oily materials.  

PubMed

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

Phuphuakrat, Thana; Namioka, Tomoaki; Yoshikawa, Kunio

2011-01-01

131

Determination of soil–water sorption coefficients of volatile methylsiloxanes  

PubMed Central

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

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

2014-01-01

132

Osmotic Coefficients and Mean Activity Coefficients of Uni-univalent Electrolytes in Water at 25°C  

Microsoft Academic Search

This paper gives values for the osmotic coefficients and mean activity coefficients of uni-univalent electrolytes in aqueous solutions at 25 °C. The values are expressed on the molality or weight basis. The data available in the literature have been corrected to the presently accepted scales of atomic weights (1969) and temperature (IPST 1968) and, where necessary, to the absolute electrical

Walter J. Hamer; Yung-Chi Wu

1972-01-01

133

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

PubMed

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

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

2004-07-01

134

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

NASA Technical Reports Server (NTRS)

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

Grundy, William M.; Fink, Uwe

1991-01-01

135

Measurement of krypton-85 in water by absorption in polycarbonates  

NASA Astrophysics Data System (ADS)

This article describes a method for quantitative measurements of Kr85 in water by absorption in polycarbonates. The method is based on exposure of polycarbonate samples in water and uses the high absorption ability to noble gases of some polycarbonates like Makrofol® and Makrolon® for sampling Kr85 from the water. After the exposure, the radiation emitted from the samples is measured by gross beta counting or gamma spectrometry. The results from the conducted experiments demonstrate a very good linear correlation between the measured signal and the activity concentration of Kr85 in the water. A possible practical application of the method is to monitor Kr85 concentration in water in at-reactor pools and wet spent fuel storage facilities.

Mitev, K.; Pressyanov, D.; Dimitrova, I.; Georgiev, S.; Boshkova, T.; Zhivkova, V.

2009-05-01

136

Determination of fixed water in rocks by infrared absorption  

USGS Publications Warehouse

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%.

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

1969-01-01

137

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

NASA Technical Reports Server (NTRS)

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.

Varanasi, Prasad

1992-01-01

138

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

PubMed Central

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

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

2014-01-01

139

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

NASA Technical Reports Server (NTRS)

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.

Wan, Zhengming; Dozier, Jeff

1992-01-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

141

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

142

Diffusion coefficients significant in modeling the absorption rate of carbon dioxide into aqueous blends of N-methyldiethanolamine and diethanolamine and of hydrogen sulfide into aqueous N-methyldiethanolamine  

SciTech Connect

Absorption rates of gaseous CO{sub 2} into aqueous blends of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) and of gaseous H{sub 2}S into aqueous MDEA were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. A numerical model for absorption, diffusion, and reaction of CO{sub 2} and H{sub 2}S in blends of MDEA, DEA, and water was developed. The model was used to regress diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} for the case of CO{sub 2} absorption and of bisulfide ion for the case of H{sub 2}S absorption from measured absorption rates. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} were obtained at 298.2 K and 318.2 K in aqueous solutions containing 50 mass % total amine at DEA:MDEA mole ratios of 1:20, 1:4, 1L3, and 2:3. H{sub 2}S absorption rates and diffusion coefficients of bisulfide ion were obtained at 298.2 K and 318.2 K in aqueous solutions containing 20, 35, and 50 mass % MDEA.

Adams, M.E.; Marshall, T.L.; Rowley, R.L. [Brigham Young Univ., Provo, UT (United States). Dept. of Chemical Engineering] [Brigham Young Univ., Provo, UT (United States). Dept. of Chemical Engineering

1998-07-01

143

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

NASA Astrophysics Data System (ADS)

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

Vigasin, A. A.

2014-11-01

144

Intestinal water absorption from select carbohydrate solutions in humans.  

PubMed

Eight men positioned a triple-lumen tube in the duodenojejunum. By use of segmental perfusion, 2, 4, 6, or 8% solutions of glucose (111-444 mM), sucrose (55-233 mM), a maltodextrin [17-67 mM, avg. chain length = 7 glucose units (7G)], or a corn syrup solid [40-160 mM, avg. chain length = 3 glucose units (3G)] were perfused at 15 ml/min for 70 min after a 30-min equilibration period. All solutions were made isotonic with NaCl, except 6 and 8% glucose solutions, which were hypertonic. An isotonic NaCl solution was perfused as control. Water absorption (range: 9-15 ml.h-1.cm-1) did not differ for the 2, 4, and 6% CHO solutions but was greater (P < 0.05) than absorption from control (3.0 +/- 2.2 ml.h-1.cm-1). The 8% glucose and 3G solutions reduced (P < 0.05) net water flux compared with their 2, 4, and 6% solutions, but 8% sucrose and 8% 7G solutions promoted water absorption equivalent to lower CHO concentrations. Water absorption was independent of [Na+] in the original solution. In the test segment, 1) Na+ flux correlated with net water flux (r = 0.72, P < 0.01), K+ (r = 0.78, P < 0.01), and [Na+] (r = 0.68, P < 0.001); 2) Na+ absorption occurred at luminal [Na+] as low as 50 mM; 3) glucose transport increased linearly over the luminal concentration range of 40-180 mM; and 4) net water flux was similar over a range of glucose-to-Na+ concentration ratios of 0.4:1 to 3.5:1.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1474096

Gisolfi, C V; Summers, R W; Schedl, H P; Bleiler, T L

1992-11-01

145

Pulsed photoacoustic calibration of a differential absorption water vapor lidar  

Microsoft Academic Search

We have designed and constructed a photoacoustic (PA) cell to be used for wavelength calibration in a water vapor differential absorption lidar (DIAL) system. This system will be used to remotely determine atmospheric H2O16 concentrations. The accuracy of these measurements depends critically on the ability to tune to and detune from lines in the water vapor spectrum. Specifically, the signal-to-noise

Anthony V. Dentamaro; Phan D. Dao

2003-01-01

146

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

E-print Network

. When the cavity is filled with a medium, some light is absorbed by the medium. Thus energy is lost from the radiation field and transferred to heat. This loss results in a reduction of the outward irradiance at the inner surface of the cavity. A fiber... define a vector irradiance F: ???= ? ? drLF ˆ),( (2.1) and a radiant energy density U: 13 ? ? ??= drLcmU ),( (2.2) where the integral is over solid angle a0, c is the speed of light in vacuum, and m is the refractive index...

Wang, Ling

2008-10-10

147

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

SciTech Connect

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

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

2014-01-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

149

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

E-print Network

solute polarizability is close to that of CO2, such as CH4, C2H6, C3H8, and H2S. Moreover, we presentModeling 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

Firoozabadi, Abbas

150

Polarizable interaction potential for water from coupled cluster calculations. II. Applications to dimer spectra, virial coefficients,  

E-print Network

-pol interaction potential for the water dimer was used to predict properties of the dimer and of liquid water with experimental high-resolution spectra. Also the virial coefficients and properties of liquid water agree well Institute of Physics. DOI: 10.1063/1.2832858 I. INTRODUCTION To understand the properties of water clusters

151

Investigation of the Emission and Absorption Spectra of Water Vapor  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

153

IOP from reflectance measurements to obtain the Kd coefficient: application to the Gabon and Congo coastal waters  

NASA Astrophysics Data System (ADS)

During the "Optic-Congo" oceanographic survey which took place in 2005 on board the "Beautemp-Beaupré" SHOM vessel, different optical measurements of the surface water were acquired using a TRIOS radiance sensor fixed onboard a mini-catamaran. Hydrological measurements (CTD, fluorescence, attenuation, scattering) and water samples were simultaneously collected in order to measure SPM, Chlorophyll-a and CDOM concentrations. Four types of surface water colours (blue, green-yellow, dark and brown) were identified. The main characteristics of these waters were the very low Chlorophyll-a concentrations for this period of the year (March), and the very high CDOM concentrations along the Congo coast, and particularly in the turbid plume of the Congo River. The attenuation and scattering measurements highlighted the predominance of organic matter at the water surface. These observations were documented using a beam electron microscope and by microanalysis. This data set was used to classify the water bodies along the Gabon and Congo coasts. We propose here to use the remote sensing reflectance (Rrs) measurements to invert the IOP (absorption (a) and backscattering (bb)) using the WASI numerical bio-optical model. The model is iterative: the Rrs WASI simulations are computed given initial values of ocean constituents' concentrations and iteratively adjusted to the Rrs in-situ measurements. The IOP computations are satisfying when the correlations between simulated and measured Rrs are optimized. Then, the attenuation coefficients (Kd) are computed from the IOP coefficients. These results are compared with measurements of Ku carried out during the survey.

Schmeltz, M.; Froidefond, J.-M.; Jourdain, F.; Martiny, N.

2009-08-01

154

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

PubMed

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

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

2014-10-01

155

Water vapor differential absorption lidar development and evaluation.  

PubMed

A ground-based differential absorption lidar (DIAL) system is described which has been developed for vertical range-resolved measurements of water vapor. The laser transmitter consists of a ruby-pumped dye laser, which is operated on a water vapor absorption line at 724.372 nm. Part of the ruby laser output is transmitted simultaneously with the dye laser output to determine atmospheric scattering and attenuation characteristics. The dye and ruby laser backscattered light is collected by a 0.5-m diam telescope, optically separated in the receiver package, and independently detected using photomultiplier tubes. Measurements of vertical water vapor concentration profiles using the DIAL system at night are discussed, and comparisons are made between the water vapor DIAL measurements and data obtained from locally launched rawinsondes. Agreement between these measurements was found to be within the uncertainty of the rawinsonde data to an altitude of 3 km. Theoretical simulations of this measurement were found to give reasonably accurate predictions of the random error of the DIAL measurements. Confidence in these calculations will permit the design of aircraft and Shuttle DIAL systems and experiments using simulation results as the basis for defining lidar system performance requirements. PMID:20216627

Browell, E V; Wilkerson, T D; McIlrath, T J

1979-10-15

156

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

NASA Astrophysics Data System (ADS)

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

Nakamura, Shigeto; Yano, Takeru

2014-12-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

158

Synoptic water clarity assessment in the Florida Keys using diffuse attenuation coefficient estimated from Landsat imagery  

Microsoft Academic Search

The diffuse attenuation coefficient, K (m? 1), is a measure of the effective attenuation of light in the water column. It characterizes water clarity and is used as a\\u000a proxy for water quality. Mapping of shallow water benthic habitats using optical means, including daytime visible satellite\\u000a imagery, requires knowledge of K to correct for water column effects such as light

D. Palandro; C. Hu; S. Andréfouët; F. E. Muller-Karger

2004-01-01

159

Changes in Correlation Coefficients with Spatial Scale and Implications for Water Resources and Vulnerability Data  

Microsoft Academic Search

Previous studies of correlation coefficients between paired observations using census, hydrologic, and remote sensing data abound. It is well established that bivariate relationships at coarser spatial resolutions are often stronger than at finer resolutions. No assessment as yet, however, corroborates this tendency with water resources variables. In this study, multiscale correlations between water use or water availability and population are

Shama Perveen; L. Allan James

2011-01-01

160

Changes in Correlation Coefficients with Spatial Scale and Implications for Water Resources and Vulnerability Data  

Microsoft Academic Search

Previous studies of correlation coefficients between paired observations using census, hydrologic, and remote sensing data abound. It is well established that bivariate relationships at coarser spatial resolutions are often stronger than at finer resolutions. No assessment as yet, however, corroborates this tendency with water resources variables. In this study, multiscale correlations between water use or water availability and population are

Shama Perveen; L. Allan James

2012-01-01

161

Water Absorption in Internally Cured Mortar Made with Water-Filled Lightweight Aggregate  

E-print Network

Water Absorption in Internally Cured Mortar Made with Water- Filled Lightweight Aggregate 1 2 3 4 5 for shrinkage cracking in low w/c concrete has spawned the development of new technologies that can reduce the risk of early-age cracking. One of these is internal curing. Internal curing uses saturated lightweight

Bentz, Dale P.

162

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

EPA Science Inventory

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

163

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...

164

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...

165

HI Absorption in the Gigamaser Galaxy TXS 2226-184 and the Relation between HI Absorption and Water Emission  

E-print Network

We report on the discovery of HI in absorption toward the gigamaser galaxy TXS2226-184 using the VLA. The absorption appears to consist of two components -- one with a width of 125 km/s, and one broader (420 km/s), both toward the compact radio source in the nucleus of the galaxy. Based on these large velocity widths we suggest that the HI absorption is produced in the central parsecs of the galaxy, on a similar scale to that which gives rise to the water maser emission. This brings to eight the number of galaxies known to exhibit both water masers and HI absorption. We explore the relationship between these two phenomena, and present a physically motivated (but unfruitful) search for water maser emission in five radio galaxies known to exhibit strong HI absorption.

G. B. Taylor; A. B. Peck; C. Henkel; H. Falcke; C. G. Mundell; C. P. O'Dea; S. A. Baum; J. F. Gallimore

2002-03-22

166

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

167

Partition coefficients of organic compounds in lipid-water systems and correlations with fish bioconcentration factors  

USGS Publications Warehouse

Triolein-water partition coefficients (KtW) have been determined for 38 slightly water-soluble organic compounds, and their magnitudes have been compared with the corresponding octanol-water partition coefficients (KOW). In the absence of major solvent-solute interaction effects in the organic solvent phase, the conventional treatment (based on Raoult's law) predicts sharply lower partition coefficients for most of the solutes in triolein because of its considerably higher molecular weight, whereas the Flory-Huggins treatment predicts higher partition coefficients with triolein. The data are in much better agreement with the Flory-Huggins model. As expected from the similarity in the partition coefficients, the water solubility (which was previously found to be the major determinant of the KOW) is also the major determinant for the Ktw. When the published BCF values (bioconcentration factors) of organic compounds in fish are based on the lipid content rather than on total mass, they are approximately equal to the Ktw, which suggests at least near equilibrium for solute partitioning between water and fish lipid. The close correlation between Ktw and Kow suggests that Kow is also a good predictor for lipid-water partition coefficients and bioconcentration factors.

Chiou, C.T.

1985-01-01

168

Effect of atmospheric environment on the attenuation coefficient of light in water  

E-print Network

The attenuation coefficient of 532 nm light in water under different atmospheric conditions was investigated. Measurements were made over a two-year period at the same location and show that the attenuation coefficient is significantly influenced by the atmospheric environment. It is lowest when the atmospheric pressure is high and temperature is low, and is highest when the atmospheric pressure is low and temperature is high. The maximum attenuation coefficient of pure water in these studies was about three times the minimum value. The mechanism of the phenomena is discussed. These results are also important in underwater acoustics.

Liu, Juan; Tang, Yijun; Zhu, Kaixing; Ge, Yuan; Chen, Xuegang; He, Xingdao; Liu, Dahe

2014-01-01

169

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

170

Prediction of Air and Water Film Coefficients in Cooling Towers from Penetration Theory  

NASA Astrophysics Data System (ADS)

In the experimental analysis of cooling towers, it is not necessarily easy to obtain the values of air and water phase film volumetric coefficients, because the experimental conditions are limited to which the Mickley's graphical method is applicable. The purpose of this study is to predict the individual coefficients using more practical method based on the penetration theory for water film. The tower used in this study is of a commercial induced draft counterflow type. Water-cooling experiments were made with constantly designed air and water flow rates and with varied water temperatures. Then, we attempted to predict the individual coefficients from these over-all results by means of the reported procedure. Finally, applying our method to the similar experimental date of other workers, we obtained nearly equal results compared with the Mickley's method.

Yazaki, Yoshimu; Yoshioka, Hideaki

171

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

E-print Network

#12;AN AMMONIA-WATER ABSORPTION-HIAT-PUMP CYCLE BY Donald Kuhlenschmidt, Member ASHRAE Richard H. Merrick, Member ASHRAE ABSTRACT The scate-of-art in ammonia-water absorption cooling has been applied,000 Btuh) input unit reported. KLY WORDS Absorption Heat-pump Air conditioning heating Ammonia Donald

Oak Ridge National Laboratory

172

Capacity for Absorption of Water-Soluble Secondary Metabolites Greater in Birds than in Rodents  

E-print Network

Capacity for Absorption of Water-Soluble Secondary Metabolites Greater in Birds than in Rodents methodology to measure absorption of two radiolabeled, inert, neutral water-soluble probes that do). We also measured absorption of labeled 3-O-methyl-D-glucose (3OMD-glucose; Mr = 194.2 Da), which

Mladenoff, David

173

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

Microsoft Academic Search

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

Ashok Sinha; John E. Harries

1995-01-01

174

Development of self-absorption coefficients for the determination of gamma-emitting radionuclides in environmental and mixed waste samples  

SciTech Connect

As the need for rapid and more accurate determinations of gamma-emitting radionuclides in environmental and mixed waste samples grows, there is continued interest in the development of theoretical tools to eliminate the need for some laboratory analyses and to enhance the quality of information from necessary analyses. In gamma spectrometry the use of theoretical self-absorption coefficients (SACs) can eliminate the need to determine the SAC empirically by counting a known source through each sample. This empirical approach requires extra counting time and introduces another source of counting error, which must be included in the calculation of results. The empirical determination of SACs is routinely used when the nuclides of interest are specified; theoretical determination of the SAC can enhance the information for the analysis of true unknowns, where there may be no prior knowledge about radionuclides present in a sample. Determination of an exact SAC does require knowledge about the total composition of a sample. In support of the Department of Energy`s (DOE) Environmental Survey Program, the Analytical Chemistry Laboratory (ACL) at Argonne National Laboratory developed theoretical self-absorption models to estimate SACs for the determination of non-specified radionuclides in samples of unknown, widely-varying, compositions. Subsequently, another SAC model, in a different counting geometry and for specified nuclides, was developed for another application. These two models are now used routinely for the determination of gamma-emitting radionuclides in a wide variety of environmental and mixed waste samples.

Streets, W.E.

1994-05-01

175

Water absorption in a refractive index model for bacterial spores  

NASA Astrophysics Data System (ADS)

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.

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

176

Depth profiling the optical absorption and thermal reflection coefficient via an analysis based on the method of images (abstract)  

NASA Astrophysics Data System (ADS)

The problem of depth profiling optical absorption in a thermally depth variable solid is a problem of direct interest for the analysis of complex structured materials. In this work, we introduce a new algorithm to solve this problem in a planar layered sample which is impulse irradiated. The sample is comprised of "N" model layers of thickness ?x, of constant diffusivity ?, where the conductivity varies depth wise with each layer. This derivation extends to the general case of a depth variable thermal reflection coefficient with depth variable optical source density. In such a sample, at finite time, t, past excitation, thermal energy can only significantly penetrate NL model layers NL??4?t[-ln(?)] /2?x, where ? is a small error (??10-6) and a double transit through each layer is assumed. The depth profile of optical absorption in each layer, i, is approximated by ?(x-i?x), weighted by the optical source density Si. The temperature at x=0- just inside a front medium contacting the sample is given by T(x=0,t)= ? i=12NL Si?GR(x,x0=i?x,t)]x=0, where GR(x,x0,t) represents an effective Green's function for optical absorption at the depth x0=i?x in the sample. The method of images1 gives GR(x,x0=i?x,t) in the following form: [GR(x,0?x,t)GR(x,2?x,t)…GR(x,2NL?x,t)]=[A10A12 A14 A16 …..A1,2NL0A32A34 A36 …..A3,2NL….0……A2NL-1,2NL][G(x-0?x,t)G(x-2?x,t)……G(x-2NL?x,t)]. The G(x-n?x,t) are shifted image fields obtained from the infinite domain Green's function for one-dimensional heat conduction. They account for thermal wave reflection/transmission over the path length n?x from the source (at interface i) to the surface (x=0). The Ain are lumped coefficients giving the efficiency of heat transmission from the ith source to the surface for each path order n. They are determined by a mapping procedure that identifies all propagation paths of each order, n, and computes the individual and lumped reflection coefficients. Equation (2) is written for sources placed at odd ordered model interfaces. A similar upper triangular matrix results for the placement of sources at the even ordered interfaces. Recovery of the optical absorption profile proceeds by inversion of Eq. (1) for known GR(x,i?x,t). Determination of the kernel requires a solution of the related type II inverse problem.2,3 An evaluation of this procedure and its conditioning will be presented.

Power, J. F.

2003-01-01

177

Some evaluations of drag and bulk transfer coefficients over water bodies of different sizes  

Microsoft Academic Search

Three recent experiments allow evaluation of the bulk transfer coefficients for momentum, water vapour and sensible heat over water bodies of different sizes. As part of a study of evaporation rates from a swamp, measurements of latent and sensible heat fluxes were made over Lake Wyangan in southern N.S.W., Australia. This lake is of several kilometers diameter. In a later

B. B. Hicks

1972-01-01

178

Combined Raman lidar for the measurement of atmospheric temperature, water vapor, particle extinction coefficient, and particle backscatter coefficient.  

PubMed

The lidar of the Radio Science Center for Space and Atmosphere (RASC; Kyoto, Japan) make use of two pure rotational Raman (MR) signals for both the measurement of the atmospheric temperature profile and the derivation of a temperature-independent Raman reference signal. The latter technique is new and leads to significant smaller measurement uncertainties compared with the commonly used vibrational Raman lidar technique. For the measurement of temperature, particle extinction coefficient, particle backscatter coefficient, and humidity simultaneously, only four lidar signal are needed the elastic Cabannes backscatter signal, two RR signals, and the vibrational Raman water vapor signal. The RASC lidar provides RR signals of unprecedented intensity. Although only 25% of the RR signal intensities can be used with the present data-acquisition electronics, the 1-s -statistical uncertainty of nighttime temperature measurements is lower than for previous systems and is < 1K up to 11-km height for, e.g., a resolution of 500 m and 9 min. In addition, RR measurements in daytime also have become feasible. PMID:12510935

Behrendt, Andreas; Nakamura, Takuji; Onishi, Michitaka; Baumgart, Rudolf; Tsuda, Toshitaka

2002-12-20

179

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

180

A method to obtain the absorption coefficient spectrum of single grain coal in the aliphatic C-H stretching region using infrared transflection microspectroscopy.  

PubMed

A method was developed to obtain the absorption coefficient spectrum of a grain of coal (as small as 10(-7)) in the region of aliphatic and aromatic C-H stretching bands (2700-3200 cm(-1)) using infrared transflection microspectroscopy. In this method, the complex refractive index n - ik was determined using an optimization algorithm with the Kramers-Kronig transform so that the calculated transflection spectrum from the Fresnel equation corresponded to the measured one. The obtained absorption coefficients were compared with the bulk values determined from the potassium bromide (KBr) pellet measurement method. PMID:25014839

Tonoue, Ryota; Katsura, Makoto; Hamamoto, Mai; Bessho, Hiroki; Nakashima, Satoru

2014-01-01

181

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

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.

Thomas, B.L.

1984-07-01

182

J-dependence of the lineshift coefficients in the ?2 water vapor band.  

NASA Astrophysics Data System (ADS)

The nitrogen pressure shifting coefficients for the 150 water vapor lines in the ?2 band have been measured with the Fourier transform spectrometer located at the Paris VI University with the spectral resolution of 0.005 cm-1 and at room temperature. The measurements were performed for lines having lower state angular moment up to 16, the measured values are found to range from +0.015 to -0.0293 cm-1/atm. The J-dependence of the line shift coefficients was studied using the Anderson-Tsao-Curnutte model and cut-of-free method. Fairly satisfactory agreement between measured and calculated line shift coefficients has been found.

Valentin, A.; Rachet, F.; Bykov, A. D.; Lavrentieva, N. N.; Saveliev, V. N.; Sinitsa, L. N.

1998-05-01

183

Infrared Thermography applied to measurement of Heat transfer coefficient of water in a pipe heated by Joule effect  

E-print Network

Infrared Thermography applied to measurement of Heat transfer coefficient of water in a pipe heated. It has been applied to measure heat transfer coefficients of water flowing in a round tube and in a multiport-flat tube. Models were developed to deduce heat transfer coefficient from wall temperature

Boyer, Edmond

184

Gas holdup, power consumption, and oxygen absorption coefficient in a stirred-tank fermentor under foam control.  

PubMed

For a laboratory stirred-tank fermentor (STF) with foaming system of 0.5M sulfite solution containing an anionic soft detergent, the performing of a foam-breaking apparatus with a rotating disk (FARD)fitted to the STF was evaluated. The gas holdup in a mechanical foam-control system (MFS), i.e., the stirred-tank fermentor with the rotating disk foambreaker, was confirmed to be larger than that in a nonfoaming system (NS), i.e., the STF with an antifoam agent added. The agitation power in the mechanical foam control system was found to be smaller compared with the agitation power in the nonfoaming system, due to the increased gas holdup. Comparison of the oxygen absorption coefficient between the mechanical foam control system and the nonfoaming system in terms of the specific power input also demonstrated the superiority of the mechanical foam control system, not only in oxygen transfer performance but also in power input economy. PMID:18604881

Yasukawa, M; Onodera, M; Yamagiwa, K; Ohkawa, A

1991-09-01

185

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

PubMed

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

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

2014-12-01

186

Simultaneous Measurement of Thermal Diffusivity and Optical Absorption Coefficient of Solids Using PTR and PPE: A Comparison  

NASA Astrophysics Data System (ADS)

Modulated photothermal radiometry (PTR) and a modulated photopyroelectric (PPE) technique have been widely used to measure the thermal diffusivity of bulk materials. The method is based on illuminating the sample with a plane light beam and measuring the infrared emission with an infrared detector (PTR) or the electric voltage produced by a pyroelectric sensor in contact with the sample (PPE). The amplitude and phase of both photothermal signals are recorded as a function of the modulation frequency and then fitted to the theoretical model. In this work, we compare the ability of modulated PTR and PPE to retrieve simultaneously the thermal diffusivity and the optical absorption coefficient of homogeneous slabs. In order to eliminate the instrumental factor, self-normalization is used, i.e., the ratio of the photothermal signal recorded at the rear and front surfaces. The influence of the multiple reflections of the light beam and the transparency to infrared wavelengths are analyzed. Measurements performed on a wide variety of homogeneous materials, transparent and opaque, good and bad thermal conductors, confirm the validity of the method. The advantages and disadvantages of both techniques are discussed.

Fuente, R.; Mendioroz, A.; Apiñaniz, E.; Salazar, A.

2012-11-01

187

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

NASA Astrophysics Data System (ADS)

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

Sokoletsky, Leonid; Yang, Xianping; Shen, Fang

2014-11-01

188

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

PubMed

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

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

2013-11-01

189

Infinite Dilution Activity Coefficients of Acetone in Water A New Experimental Method and Verification  

E-print Network

Infinite Dilution Activity Coefficients of Acetone in Water A New Experimental Method region. However, this is solution model dependent, i.e. different models describing the same acetone of the resultant values. Results for acetone are reported and compared to literature values. The comparison

Howat, Colin S. "Chip"

190

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...

191

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 ...

192

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...

193

ESTIMATION OF OCTANOL/WATER PARTITION COEFFICIENTS FOR ORGANIC POLLUTANTS USING REVERSE-PHASE HPLC  

EPA Science Inventory

Octanol/water partition coefficients (K(ow's)) of organic solutes are estimated with reasonable accuracy (standard deviation + or - 0.25 log K(ow)units) by elution from a C-18 column with 75:25 (v/v) MeOH-H20, based on results with 37 test compounds. Changes in solute activity co...

194

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

195

THE EFFECT OF TEMPERATURE ON THE ABSORPTION OF WATER BY SODA-BOILED COTTON  

Microsoft Academic Search

Little work has hitherto been published on the effect of temperature on the absorption of water by cotton, and no data were available for temperatures higher than 38°C. The present experiments deal with the absorption of water by cotton, at all humidities and at temperatures up to 110°C., the data being therefore of practical application not only to the testing

Alexander Robert Urquhart; Alexander Mitchell Williams

1924-01-01

196

Direct Measurement of Water Cluster Concentrations by Infrared Cavity Ringdown Laser Absorption Spectroscopy  

E-print Network

method for measuring infrared spectra, infrared cavity ringdown laser absorption spectroscopy (IR in the terahertz (far- infrared) region of the spectrum,6 water clusters have been studied primarily in the midDirect Measurement of Water Cluster Concentrations by Infrared Cavity Ringdown Laser Absorption

Cohen, Ronald C.

197

Determination of the water vapor continuum absorption by THz-TDS and Molecular  

E-print Network

Determination of the water vapor continuum absorption by THz-TDS and Molecular Response Theory: Determination of the water vapor continuum absorption from 0.35 to 1 THz is reported. The THz pulses propagate though a 137 m long humidity-controlled chamber and are measured by THz time-domain spectroscopy (THz

Oklahoma State University

198

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

PubMed

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

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

2012-06-28

199

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

PubMed

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

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

2013-09-01

200

Thermal lens measurement of the Soret coefficient in acetone/water mixtures.  

PubMed

The Soret coefficient of acetone/water mixtures has been experimentally determined by a recently developed thermal lens technique [Appl. Phys. Lett. 94, 051103 (2009)]. The behavior of the Soret coefficient was reproduced, including its sign change with composition. For concentrations around the equimolar ones, we have also confirmed the disagreement between the experimental and simulation data that had previously been reported by Ning and Wiegand [J. Chem. Phys. 125, 221102 (2006)] using a transient holographic grating technique of thermal diffusion forced Rayleigh scattering. Additionally, we compare our experimental results with the theoretical values predicted by a recently developed viscous energy model [J. Chem. Phys. 130, 064506 (2009)]. PMID:19624174

Cabrera, Humberto; Martí-López, Luis; Sira, Eloy; Rahn, Kareem; García-Sucre, Máximo

2009-07-21

201

Modeling infinite dilution activity coefficients of environmental pollutants in water using conformal solution theory  

SciTech Connect

The fate of organic pollutants in the environment and in wastewater treatment processes is commonly modeled using a Henry`s law constant approach. By definition, Henry`s law constant is the product of a compound`s vapor pressure and infinite dilution activity coefficient. For many organic compounds in water solution, the infinite dilution activity coefficients are very large and are not adequately modeled by conventional methods such as UNIFAC. In this work, infinite dilution activity coefficients were determined for phenol, pyridine, aniline, p-toluidine, and o-toluidine in water by differential ebulliometry. An equation rigorously derived from conformal solution theory and van der Waals one-fluid mixing rules was used to model the temperature dependency of the infinite dilution activity coefficients. No corrections other than the introduction of two adjustable parameters were incorporated into the model to account for the strong interactions between molecules. Relationships derived from corresponding states theory were used to relate molecular parameters for size and energy interaction to the critical properties. Arithmetic mean combining rules and geometric mean combining rules were used to calculate size and interaction parameters, respectively.

Moore, R.C. [Univ. of Tennessee, Knoxville, TN (United States); Cochran, H.D.; Bienkowski, P.R. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Laboratory, Oak Ridge, TN (United States)

1995-04-01

202

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)

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.

Pawlak, M.

2014-11-01

203

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)

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.

Pawlak, M.

2015-01-01

204

Limitations arising from two-photon absorption of solvent in pulsed-laser thermal lens detection: determination of the two-photon absorption coefficient of ethanol at 266 nm.  

PubMed

Two-photon absorption of the solvent under pulsed-laser excitation at 266 nm produces a high background thermal lens signal interfering with the analyte signal. Discrimination of both solvent and analyte signals along with calibration of the photothermal response has allowed the determination of the two-photon absorption coefficient of ethanol. The obtained value, 3.0x10(-10) cm W-1, is close to the literature values obtained from transmittance measurements using picosecond or femtosecond laser pulses. PMID:16454917

Abbas Ghaleb, Khalil; Georges, Joseph

2006-01-01

205

Experimental study on the heat transfer coefficient of water flow boiling in mini\\/microchannels  

Microsoft Academic Search

The heat transfer coefficients of the evaporative water flow in mini\\/microchannels are studied experimentally to explore the novel heat dissipation for high power electronics. Two sets of parallel channels which are 61 channels with hydraulic diameter of 0.293mm and 20 channels with hydraulic diameter of 1.2mm are investigated respectively. The inlet and outlet temperatures of fluids, and the temperatures beneath

DongYao Liu; Xia Weng; XiaoGuang Xu

2011-01-01

206

Optical absorption of pure water in the blue and ultraviolet  

E-print Network

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...

Lu, Zheng

2007-09-17

207

Various contributions to the osmotic second virial coefficient in protein-water-cosolvent solutions.  

PubMed

An analysis of the cosolvent concentration dependence of the osmotic second virial coefficient (OSVC) in water-protein-cosolvent mixtures is developed. The Kirkwood-Buff fluctuation theory for ternary mixtures is used as the main theoretical tool. On its basis, the OSVC is expressed in terms of the thermodynamic properties of infinitely dilute (with respect to the protein) water-protein-cosolvent mixtures. These properties can be divided into two groups: (1) those of infinitely dilute protein solutions (such as the partial molar volume of a protein at infinite dilution and the derivatives of the protein activity coefficient with respect to the protein and water molar fractions) and (2) those of the protein-free water-cosolvent mixture (such as its concentrations, the isothermal compressibility, the partial molar volumes, and the derivative of the water activity coefficient with respect to the water molar fraction). Expressions are derived for the OSVC of ideal mixtures and for a mixture in which only the binary mixed solvent is ideal. The latter expression contains three contributions: (1) one due to the protein-solvent interactions B2(p-s), which is connected to the preferential binding parameter, (2) another one due to protein/protein interactions (B2(p-p)), and (3) a third one representing an ideal mixture contribution (B2(id)). The cosolvent composition dependencies of these three contributions were examined for several water-protein-cosolvent mixtures using experimental data regarding the OSVC and the preferential binding parameter. For the water-lysozyme-arginine mixture, it was found that OSVC exhibits the behavior of an ideal mixture and that B2(id) provides the main contribution to the OSVC. For the other mixtures considered (water-Hm MalDH-NaCl, water-Hm MalDH-(NH4)2SO4, and water-lysozyme-NaCl mixtures), it was found that the contribution of the protein-solvent interactions B2(p-s) is responsible for the composition dependence of the OSVC on the cosolvent concentration, whereas the two remaining contributions (B2(p-p)) and B2(id)) are almost composition independent. PMID:18698703

Shulgin, Ivan L; Ruckenstein, Eli

2008-11-20

208

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

PubMed

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

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

2012-12-21

209

Parameters and computer software for the evaluation of mass attenuation and mass energy-absorption coefficients for body tissues and substitutes  

PubMed Central

The mass attenuation and energy-absorption coefficients (radiation interaction data), which are widely used in the shielding and dosimetry of X-rays used for medical diagnostic and orthovoltage therapeutic procedures, are strongly dependent on the energy of photons, elements and percentage by weight of elements in body tissues and substitutes. Significant disparities exist in the values of percentage by weight of elements reported in literature for body tissues and substitutes for individuals of different ages, genders and states of health. Often, interested parties are in need of these radiation interaction data for body tissues or substitutes with percentage by weight of elements and intermediate energies that are not tabulated in literature. To provide for the use of more precise values of these radiation interaction data, parameters and computer programs, MUA_T and MUEN_T are presented for the computation of mass attenuation and energy-absorption coefficients for body tissues and substitutes of arbitrary percentage-by-weight elemental composition and photon energy ranging between 1 keV (or k-edge) and 400 keV. Results are presented, which show that the values of mass attenuation and energy-absorption coefficients obtained from computer programs are in good agreement with those reported in literature. PMID:21157532

Okunade, Akintunde A.

2007-01-01

210

Exponential Sum Absorption Coefficients of Phosphine from 2750 to 3550/cm for Application to Radiative Transfer Analyses on Jupiter and Saturn  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

211

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)

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.

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

1993-03-01

212

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

213

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

Microsoft Academic Search

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

Robin M. Pope; Edward S. Fry

1997-01-01

214

Absorption  

NSDL National Science Digital Library

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 SocietyÃÂs 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.

Katherine M Knudson (Polson Middle School)

1998-04-01

215

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

Microsoft Academic Search

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

Philip W. Rosenkranz

1998-01-01

216

Inverse temperature dependence of Henry's law coefficients for volatile organic compounds in supercooled water.  

PubMed

Upon supercooling, water expels volatile organic compounds (VOC), and Henry's law coefficients are increasing concomitant with decreasing temperature. This unexpected observation was found by measuring the VOC partitioning between supercooled water and gas phase in the temperature range from -5 degrees C to -15 degrees C for benzene, toluene, ethlybenzene, m-, p-, o-xylenes (BTEX), methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE). Aqueous standard solutions were analyzed using a static headspace method in combination with gas chromatography/mass spectrometry (GC/MS). Dimensionless Henry's law coefficients (K(AW)) were calculated from measurements of the concentration of the VOCs in the headspace above the standard solutions at temperatures between -25 degrees C and 25 degrees C. The results show that the well known temperature dependence of Henry's law coefficients at temperatures above 0 degrees C is inversed upon decreasing the temperature below 0 degrees C and formation of supercooled water while decreasing the temperature to -15 degrees C. Upon further decrease of the temperature to -25 degrees C freezing of the supercooled water occurs. K(AW) values increase from 0.092 (benzene), 0.099 (toluene), 0.098 (ethylbenzene), 0.117 (m/p-xylene), 0.076 (o-xylene), 0.012 (MTBE) and 0.014 (ETBE at 5 degrees C to 0.298 (benzene), 0.498 (toluene), 0.944 (ethylbenzene), 0.327 (m/p-xylene), 0.342 (o-xylene), 0.029 (MTBE) and 0.041 (ETBE) at -25 degrees C, respectively. Inversion of Henry coefficients upon cooling the aqueous solutions to temperatures below 0 degrees C is explained by the increasing formation of ice-like clusters in the water below 0 degrees C. The VOC are expelled from these clusters resulting in enhanced VOC concentrations in the gas phase upon supercooling. Formation of ice upon further cooling to -25 degrees C results in a further increase of the VOC concentrations in the gas phase above the ice. The findings have implications for the partitioning of VOC in clouds between the gas phase, supercooled water droplets, aerosol particles and ice. PMID:19604535

Sieg, Karsten; Starokozhev, Elena; Schmidt, Martin U; Püttmann, Wilhelm

2009-09-01

217

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

218

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

NASA Technical Reports Server (NTRS)

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).

Lal, M.; Chakrabarty, D. K.

1994-01-01

219

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

PubMed Central

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

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

220

Relationships between octan?1?ol\\/water partition coefficients, aqueous activity coefficients and reversed phase HPLC capacity factors of alkylbenzenes, chlorobenzenes, chloronaphthalenes and chlorobiphenyls  

Microsoft Academic Search

Linear relationships between logarithms of octan?1?ol\\/water partition coefficients (Kd,oct), aqueous activity coefficients (yaq) and extrapolated RP HPLC capacity factors (k‘w) are found for four types of aromatic hydrocarbons (alkylbenzenes and poly?chlorinated benzenes, ?naphthalenes and ?biphenyls).Both log K,d,oct and logk‘w increase with the increasing number of chlorine or methyl?ene substituents. These increases of log K,d,oct and log k‘w are proportional and

Antoon Opperhuizen

1987-01-01

221

A WATER VAPOR MONITOR USING DIFFERENTIAL INFRARED ABSORPTION  

EPA Science Inventory

A water vapor monitor has been developed with adequate sensitivity and versatility for a variety of applications. Two applications for which the instrument has been designed are the continuous monitoring of water in ambient air and the measuring of the mass of water desorbed from...

222

Water and solute absorption from hypotonic glucose-electrolyte solutions in human jejunum.  

PubMed Central

While oral rehydration therapy with glucose-electrolyte solutions is highly effective, the optimal formulation has not yet been defined. Recent clinical studies suggest that stool volume, and thus water losses, may be reduced if glucose is replaced by a polymeric substrate which reduces osmolality. It is possible that the efficacy of glucose monomer based oral rehydration solutions (ORS) will also improve if osmolality is decreased. Using jejunal triple lumen perfusion in healthy adult volunteers net water and solute absorption were studied from three hypotonic solutions with different sodium concentrations (46, 60, 75 mmol/l) but identical glucose concentrations (90 mmol/l), thus allowing osmolality to rise (210, 240, and 270 mOsm/kg, respectively). Results from these solutions (ORS 45:210, ORS 60:240, and ORS 75:270) were compared with the World Health Organisation oral rehydration solution (WHO-ORS). Greatest water absorption was seen with ORS 60:240 (p less than 0.01). Sodium absorption from ORS 60:240 and WHO-ORS was similar and greater than sodium absorption from ORS 45:210 (p less than 0.05). Potassium and glucose absorption were greater from ORS 60:240 than from any of the other hypotonic solutions (p less than 0.05) and were equal to absorption from WHO-ORS). These results in a short segment of healthy human jejunum suggest that hypotonic ORS containing monomeric glucose may increase water absorption. PMID:1582591

Hunt, J B; Elliott, E J; Fairclough, P D; Clark, M L; Farthing, M J

1992-01-01

223

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

SciTech Connect

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.

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

2005-09-01

224

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

225

Influence of meal composition on canine jejunal water and electrolyte absorption.  

PubMed

The absorption of water and electrolytes from the proximal jejunal lumen increases immediately after a meal. This meal-induced jejunal absorption occurs in jejunal segments out of normal gastrointestinal continuity. This study was designed to characterize the jejunal absorptive response to a series of isovolumetric gavage-delivered stimuli. Twenty-five-centimeter canine proximal jejunal Thiry-Vella fistulas were constructed, and jejunal absorption studies (n = 66) were performed by luminal perfusion of the jejunal segments with an isotonic buffer containing 14C-labeled polyethylene glycol. Each study consisted of a 1-hour basal period, followed by a 3-hour experimental period. Nine groups were studied, each receiving one of the following isovolumetric stimuli delivered via the gavage route: water, 0.9% saline, mixed meal, protein, lipid, carbohydrate, and mannitol (150 mmol/L, 300 mmol/L, and 600 mmol/L). The water and 0.9% saline gavage groups showed no significant changes in integrated postprandial water and electrolyte absorption above basal. The isocaloric mixed meal, protein, lipid, carbohydrate, and mannitol groups all had significantly increased integrated postprandial jejunal water and electrolyte absorption above basal (P less than 0.05). These results indicate that a proabsorptive signal for meal-induced jejunal absorption originates from or distal to the stomach. Meal-induced jejunal absorption occurs in response to nutrients of diverse composition and is also responsive to nonnutritive solutes such as mannitol. These findings support a new role for gastric or intestinal chemo- or osmo-receptors in stimulating the neurohumoral mechanisms that mediate meal-induced jejunal absorption. PMID:1732119

Bastidas, J A; Zinner, M J; Bastidas, J A; Orandle, M S; Yeo, C J

1992-02-01

226

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

Microsoft Academic Search

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

Eric Braekevelt; Sheryl A Tittlemier; Gregg T Tomy

2003-01-01

227

Infinite dilution diffusion coefficients of [Bmim]-based ionic liquids in water and its molar conductivities  

Microsoft Academic Search

In this work, we presented new experimental data of diffusion coefficients of four [Bmim (1-butyl-3-methylimidazolium)]-based ionic liquids in water at infinite dilution for temperatures ranging from 303.2 to 323.2K using Taylor dispersion technique. The investigated ILs were [Bmim][BF4 (tetrafluoroborate)], [Bmim][MeSO4 (methylsulfate)], [Bmim][PF6 (hexafluorophosphate)], and [Bmim][CF3SO3 (trifluoromethanesulfonate)]. The molar conductivities of these ionic liquids were also measured and the infinite dilution

Chun-Li Wong; Allan N. Soriano; Meng-Hui Li

2009-01-01

228

Liquid water absorption and scattering effects in DOAS retrievals over oceans  

NASA Astrophysics Data System (ADS)

Spectral effects of liquid water are present in absorption (differential optical absorption spectroscopy - DOAS) measurements above the ocean and, if insufficiently removed, may interfere with trace gas absorptions, leading to wrong results. Currently available literature cross sections of liquid water absorption are provided in coarser resolution than DOAS applications require, and vibrational Raman scattering (VRS) is mostly not considered, or is compensated for using simulated pseudo cross sections from radiative transfer modeling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS (Multi-AXis differential optical absorption spectroscopy) measurements of light penetrating very clear natural waters were performed, achieving average underwater light paths of up to 50 m. From these measurements, the retrieval of a correction spectrum (H2Ocorr) is presented, compensating simultaneously for insufficiencies in the liquid water absorption cross section and broad-banded VRS structures. Small-banded structures caused by VRS were found to be very efficiently compensated for by the intensity offset correction included in the DOAS fit. No interference between the H2Ocorr spectrum and phytoplankton absorption was found. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality, and performed better than using a liquid water cross section in combination with a simulated VRS spectrum. The decrease in the residual root mean square (rms) of the DOAS fit depends on the measurement's contamination with liquid water structures, and ranges from ? 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ocorr spectrum was found to prevent misfits of NO2 slant columns, especially for very low NO2 scenarios, and thus increases the reliability of the fit. In test fits on OMI satellite data, the H2Ocorr spectrum was found selectively above ocean surfaces, where it decreases the rms by up to ? 11 %.

Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

2014-12-01

229

Investigating the influence of incomplete separation of sediment and water on experimental sorption coefficients of chlorinated benzenes  

Microsoft Academic Search

The influence of incomplete separation of water and sediment in batch sorption experiments was investigated with five chlorinated benzenes. Only the sorption coefficients of the most hydrophobic chemical, hexachlorobenzene, decreased with increasing sediment\\/water ratios. This decrease is assumed to be caused by an increasing amount of sediment that was not separated from the aqueous phase. To quantify this incomplete water\\/sediment

S. Marca Schrap; Manuela Haller; Antoon Opperhuizen

1995-01-01

230

Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.  

PubMed

The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions. PMID:25326892

Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario

2014-12-01

231

Characterization of penetration depth as a function of optical fiber separation at various absorption and scatter coefficients for a noninvasive metabolic sensor  

NASA Astrophysics Data System (ADS)

A visible-near IR (500-1,000nm) fiber optic sensor is under development that is intended to non-invasively assess muscle metabolism through the measurement of tissue pH and oxygen partial pressure. These parameters are calculated from the spectra of hemoglobin and myoglobin in muscle. The sensor consists of transmit (illumination) fibers and receive (detection) fibers that are coupled to a spectrometer. Light from the probe must penetrate below the surface of the skin and into a 5-10mm thick layer of muscle. A study was conducted to quantify the relationship between transmit and receive fiber separation and sensor penetration depth below the surface of the skin. A liquid phantom was created to replicate the absorption (?a) and reduced scatter coefficient (?s') profiles typically found in human blood and tissue. The phantom consisted of a solution of Intralipid and India ink in the appropriate concentrations to achieve desired reduced scatter coefficient and absorption profiles. The reduced scatter coefficient of the liquid phantom was achieved to an accuracy of +/-10% compared to previously published data. A fixed illumination fiber and translatable detector fiber were placed in the liquid phantom, and the fiber separation was varied from 3-40mm. Values of ?a and ?s' varied from 0.03-0.40 cm-1 and 5.0-15.0 cm-1 respectively. Results from the experiment demonstrate a strong correlation between penetration depth and fiber separation. Additionally, it was found that penetration depth was not substantially influenced by absorption and scatter concentration. As signal-to-noise is an important parameter in many non-invasive biomedical applications, the relative signal as a function of fiber separation was determined to follow an exponential relationship.

DeMilo, Charles; Brukilacchio, Thomas; Soller, Babs R.; Soyemi, Olusola

2004-06-01

232

New laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 ?m) and ultraviolet (300-350 nm) spectral regions.  

PubMed

Knowing the ozone absorption cross sections in the ultraviolet and infrared spectral range, with an accuracy of better than 1%, is of the utmost importance for atmospheric remote-sensing applications. For this reason, various ozone intensity intercomparisons and measurements have been published these last years. However, the corresponding results proved not to be consistent and thus have raised a controversial discussion in the community of atmospheric remote-sensing. This study, where great care has been taken to avoid any possible error, reports a new laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 ?m) and ultraviolet (300-350 nm) spectral regions. It gives a new piece of information to the puzzling problem concerning the ozone IR and UV cross sections and confirms that the IR and UV cross sections recommended in the literature are in disagreement of about 4%. PMID:20795682

Gratien, A; Picquet-Varrault, B; Orphal, J; Doussin, J-F; Flaud, J-M

2010-09-23

233

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

NASA Astrophysics Data System (ADS)

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

Nofuentes, M.; Polo, M. J.

2012-04-01

234

Wetting and absorption of water drops on Nafion films.  

PubMed

Water drops on Nafion films caused the surface to switch from being hydrophobic to being hydrophilic. Contact angle hysteresis of >70 degrees between advancing and receding values were obtained by the Wilhelmy plate technique. Sessile drop measurements were consistent with the advancing contact angle; the sessile drop contact angle was 108 degrees . Water drop adhesion, as measured by the detachment angle on an inclined plane, showed much stronger water adhesion on Nafion than Teflon. Sessile water and methanol drops caused dry Nafion films to deflect. The flexure went through a maximum with time. Flexure increased with contact area of the drop, but was insensitive to the film thickness. Methanol drops spread more on Nafion and caused larger film flexure than water. The results suggest that the Nafion surface was initially hydrophobic but water and methanol drops caused hydrophilic sulfonic acid domains to be drawn to the Nafion surface. Local swelling of the film beneath the water drop caused the film to buckle. The maximum flexure is suggested to result from motion of a water swelling front through the Nafion film. PMID:18611043

Goswami, Sharonmoyee; Klaus, Shannon; Benziger, Jay

2008-08-19

235

Parameter identifiability and Extended Multiple Studies Analysis of a compartmental model for human vitamin A kinetics: fixing fractional transfer coefficients for the initial steps in the absorptive process.  

PubMed

In the existing compartmental models of human vitamin A metabolism, parameters related to the absorption of the isotopic oral dose have not been well identified. We hypothesised that fixing some poorly identified parameters related to vitamin A absorption would improve parameter identifiability and add statistical certainty to such models. In the present study, data for serum vitamin A kinetics in nine subjects given [2H8]retinyl acetate orally and a model with absorption fixed at 75 % were used to test this hypothesis. In addition to absorption efficiency, we fixed two other fractional transfer coefficients: one representing the initial processing of the ingested dose and the other representing the direct secretion of retinol bound to retinol-binding protein (RBP) from enterocytes into the plasma. The Windows version of Simulation, Analysis and Modeling software (WinSAAM) was used to fit serum tracer data v. time for each subject. Then, a population model was generated by WinSAAM's Extended Multiple Studies Analysis. All the parameters had fractional standard deviations < 0·5, and none of the pairs of parameters had a correlation coefficient >0·8 (accepted criteria for well-identified parameters). Similar to the values predicted by the original model, total traced mass for retinol was 1160 (sd 468) ?mol, and the time for retinol to appear in the plasma bound to RBP was 31·3 (sd 4·4) h. In conclusion, we suggest that this approach holds promise for advancing compartmental modelling of vitamin A kinetics in humans when the dose must be administered orally. PMID:24229649

Park, Hyunjin; Green, Michael H

2014-03-28

236

Water vapor profiling using a widely tunable amplified diode laser Differential Absorption Lidar (DIAL)  

Microsoft Academic Search

Water vapor is one of the most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water vapor and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the

Michael Drew Obland

2007-01-01

237

Dynamics of Water Absorption and Evaporation During Methanol Droplet Combustion in Microgravity  

NASA Technical Reports Server (NTRS)

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.

Hicks, Michael C.; Dietrich, Daniel L.; Nayagam, Vedha; Williams, Forman A.

2012-01-01

238

Air-cooled LiBr–water absorption chillers for solar air conditioning in extremely hot weathers  

Microsoft Academic Search

A low temperature-driven absorption cycle is theoretically investigated for the development of an air-cooled LiBr–water absorption chiller to be combined with low-cost flat solar collectors for solar air conditioning in hot and dry regions. The cycle works with dilute LiBr–water solutions so that risk of LiBr crystallization is less than for commercially available water-cooled LiBr–water absorption chillers even in extremely

D. S. Kim; C. A. Infante Ferreira

2009-01-01

239

Methods for analysis of selected metals in water by atomic absorption  

USGS Publications Warehouse

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.

Fishman, Marvin J.; Downs, Sanford C.

1966-01-01

240

Uncertainties in dose coefficients for intakes of tritiated water and organically bound forms of tritium by members of the public.  

PubMed

The International Commission on Radiological Protection (ICRP) provides models for the calculation of doses from intakes of radionuclides, including intakes of tritium as tritiated water (HTO) or organically bound tritium (OBT). The ICRP models for HTO and OBT are explained and the assumptions made are examined. The reliability of dose estimates is assessed in terms of uncertainties in central estimates for population groups. The models consider intakes of HTO and OBT by ingestion and inhalation by adults and children and doses to the fetus following intakes by the mother. The analysis includes uncertainties in the absorption of OBT to blood, incorporation of tritium into OBT in body tissues, retention times in tissues, transfer to the fetus and the relative biological effectiveness (RBE) of tritium beta emissions compared with gamma rays. Heterogeneity of dose within tissues and cells is also considered. For intakes as HTO, dose is predominantly due to distribution and retention of HTO in body water and it was concluded that adult doses are reliable to within a factor of 2. For intakes of OBT, the extent of incorporation into OBT in body tissues results in greater uncertainties with estimates relying on animal data for selected compounds. The analysis indicated that adult doses from OBT can be considered to be known to within a factor of 3. Greater uncertainties in estimated doses for children and for in utero exposures were considered. Central values from the uncertainty analyses of doses for HTO and OBT were greater than the corresponding ICRP dose coefficients by about a factor of 2, mainly due to the inclusion of uncertainties in RBE for tritium. A detailed assessment of doses using appropriate parameters and considering uncertainties would be of particular importance in situations where the dose may approach dose limits or constraints. For exposures to known forms of OBT, specific dose assessments may be required. PMID:12018747

Harrison, J D; Khursheed, A; Lambert, B E

2002-01-01

241

Structural Change of the Mixtures of Ionic Liquid and Water Studied by Infrared Absorption Spectroscopy  

Microsoft Academic Search

Infrared absorption spectra of the mixtures of ionic liquid and water (1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM]BF4) with varying concentrations were obtained by Attenuated Total Reflection (ATR) method. Investigation of the spectra in the OH-stretch vibration range indicated the structural change of the water with the change in the concentration. At very low concentration of water, two peaks around 3600cm-1 were assigned to

Doseok Kim; Yoonnam Jeon; Jaeho Sung; Yukio Ouchi

2006-01-01

242

Blueshifting the onset of optical UV absorption for water under pressure.  

PubMed

First-principles calculations show that the optical UV absorption onset of solid water is blueshifted with increasing pressure. Across several crystal structures and a wide pressure range, the optical gap increases almost linearly with external pressure, making solid water more transparent. The origin of this unusual effect can be traced back to an increased Stark shift caused by water's electrostatic environment at smaller volumes. PMID:21635126

Hermann, Andreas; Schwerdtfeger, Peter

2011-05-01

243

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

PubMed Central

The linear and nonlinear intraband optical absorption coefficients in GaAs three-dimensional single quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and electric field, applied along the growth direction of the heterostructure, the energies of the ground and first excited states of a donor impurity have been found using the effective mass approximation and a variational method. The energies of these states are examined as functions of the dimensions of the structure, electric field, and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as a function of incident photon energy for several configurations of the system. It is found that the variation of distinct sizes of the structure leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical spectrum. In addition, we have found that the application of an electric field leads to a redshift, whereas the influence of hydrostatic pressure leads to a blueshift (in the case of on-ring-center donor impurity position) of the resonant peaks of the intraband optical spectrum. PMID:23021497

2012-01-01

244

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

PubMed

: The linear and nonlinear intraband optical absorption coefficients in GaAs three-dimensional single quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and electric field, applied along the growth direction of the heterostructure, the energies of the ground and first excited states of a donor impurity have been found using the effective mass approximation and a variational method. The energies of these states are examined as functions of the dimensions of the structure, electric field, and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as a function of incident photon energy for several configurations of the system. It is found that the variation of distinct sizes of the structure leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical spectrum. In addition, we have found that the application of an electric field leads to a redshift, whereas the influence of hydrostatic pressure leads to a blueshift (in the case of on-ring-center donor impurity position) of the resonant peaks of the intraband optical spectrum. PMID:23021497

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

2012-01-01

245

Impact of MIE-Resonances on the Atmospheric Absorption of Water Clouds  

NASA Technical Reports Server (NTRS)

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.

Wiscombe, W.; Kinne, S.; Nussenzveig, H.; Lau, William K. M. (Technical Monitor)

2002-01-01

246

Effect of water content on strontium retardation factor and distribution coefficient in Chinese loess.  

PubMed

Geological burial and landfill are often employed for disposal of nuclear wastes. Typically, radionuclides from nuclear facilities transport through the unsaturated zone before reaching the groundwater aquifer. However, transport studies are often conducted under saturated and steady-state flow conditions. This research aimed to examine the effects of unsaturated flow conditions and soil water content (?) on Sr sorption and retardation in Chinese loess through 1D column transport experiments. Reagent SrCl2 was used as a surrogate for the radioactive isotope ((90)Sr) in the experiment because of their analogous adsorption and transportation characteristics. The spatial distribution of Sr along the column length was determined by segmenting the soil bed and analysing the Sr content in each soil segment following each column breakthrough test. The single-region (SR) and two-region (TR) models were employed to interpret the transport data of Sr as well as a tracer (Br(-)), which resulted in the dispersion coefficient (D) and retardation factor (Rd) under a given set of unsaturated flow conditions. For the tracer, the SR and TR models offered nearly the same goodness of fitting to the breakthrough curves (R(2) ? 0.97 for both models). For the highly sorptive Sr, however, the TR model provided better fitting (R(2), 0.80-0.96) to the Sr retention profiles than the SR model (R(2), 0.20-0.89). The Sr retention curves exhibited physical non-equilibrium characteristics, particularly at lower water content of the soil. For the unsaturated soil, D and the pore water velocity (v) displayed a weak linear correlation, which is attributed to the altering dispersivity as the water content varies. A much improved linear correlation was observed between D and v/?. The retardation factor of Sr increased from 69.1 to 174.2 as ? decreased from 0.46 to 0.26 (cm(3) cm(-3)), while the distribution coefficient (Kd) based on Rd remained nearly unchanged at various ? levels. These results illustrated that water content must be taken into account in determining radionuclide Rd values in Chinese loess, while Kd values can be derived from the unsaturated column experiments and can be considered constant at various levels of ?. PMID:24047556

Huo, Lijuan; Qian, Tianwei; Hao, Junting; Liu, Hongfang; Zhao, Dongye

2013-12-01

247

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...

248

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

PubMed

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

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

2014-09-15

249

Molecular Dynamics Simulations of Water/Mucus Partition Coefficients for Feeding Stimulants in Fish and the Implications for Olfaction  

PubMed Central

The odorant partition coefficient is a physicochemical property that has been shown to dramatically influence odorant deposition patterns in the mammalian nose, leading to a chromatographic separation of odorants along the sensory epithelium. It is unknown whether a similar phenomenon occurs in fish. Here we utilize molecular dynamics simulations, based on a simplified molecular model of olfactory mucus, to calculate water/mucus partition coefficients for amino acid odorants (alanine, glycine, cysteine, and valine) that are known to elicit feeding behavior in fish. Both fresh water and salt water environments are considered. In fresh water, all four amino acids prefer the olfactory mucus phase to water, and the partition coefficient is shown to correlate with amino acid hydrophobicity. In salt water, a reversal in odorant partitioning is found, where each of the feeding stimulants (except glycine) prefer the water phase to olfactory mucus. This is due to the interactions between the salt ions and the odorant molecules (in the water phase), and between the salt and simplified mucin (in the olfactory mucus phase). Thus, slightly different odorant deposition patterns may occur in the fish olfactory organ in fresh and salt water environments. However, in both underwater environments we found that the variation of the water/mucus odorant partition coefficient is approximately one order of magnitude, in stark contrast to air/mucus odorant partition coefficients that can span up to six orders of magnitude. We therefore anticipate relatively similar deposition patterns for most amino acid odorants in the fish olfactory chamber. Thus, in contrast to terrestrial species, living in an underwater environment may preclude appreciable chromatographic odorant separation that may be used for spatial coding of odor identity across the olfactory epithelium. This is consistent with the reported lack of spatial organization of olfactory receptor neurons in the fish olfactory epithelium. PMID:24023732

Rygg, Alex D.; van Duin, Adri C. T.; Craven, Brent A.

2013-01-01

250

Ab initio calculation of the electronic absorption spectrum of liquid water  

SciTech Connect

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.

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

251

Determination of oil-water partition coefficients of polar compounds: silicone membrane equilibrator vs. SPME passive sampler.  

PubMed

Experimental determination of oil-water partition coefficients often poses difficulties associated with emulsion formation. The aim of this work was to find an appropriate technique for determination of oil-water partition coefficients of polar, nonvolatile compounds. Two different methods were tested. The first method used a "silicone membrane equilibrator." For the second method, solid-phase microextraction (SPME) fibers with a polyacrylate (PA) coating were used as a passive sampler. With both methods, oil-water partition coefficients for 14 compounds with polar functional groups were determined at 37 °C with good repeatability (standard deviation 0.11 log units or lower). The partition coefficients determined with the silicone membrane equilibrator method ranged from 0.50 to 3.49 log units. The oil-water partition coefficients obtained with the PA-SPME passive sampling approach were significantly higher than those obtained with the silicone membrane equilibrator method for nine of 14 compounds. The differences were up to 0.39 log units (i.e., a factor of 2.5). Additional experiments suggested that this difference occurred because the sorption properties of the PA fibers used were influenced by the surrounding phase, e.g., through swelling of the polymer phase. Therefore, the SPME passive sampling method using PA fibers seems to be less reliable, whereas the silicone membrane equilibrator method was found to be a convenient technique for the determination of oil-water partitioning. PMID:23314485

Oemisch, Luise; Goss, Kai-Uwe; Endo, Satoshi

2013-03-01

252

Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system.  

PubMed

A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two étalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-étalon laser system. High spectral purity (> 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by usingthis laser, which has a finite linewidth of 0.02 cm(-1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(-1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity étalons is presented, and a closed-loop computer control for active stabilization of the two intracavity étalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (? 1.5 h) of less than 0.7 pm in the laboratory. PMID:20941182

Ponsardin, P; Higdon, N S; Grossmann, B E; Browell, E V

1994-09-20

253

Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system  

NASA Technical Reports Server (NTRS)

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.

Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

1994-01-01

254

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

SciTech Connect

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.

Levinson, Ronnen; Berdahl, Paul; Akbari, Hashem

2004-06-01

255

Liquid water absorption and scattering effects in DOAS retrievals over oceans  

NASA Astrophysics Data System (ADS)

It is well-known that spectral effects of liquid water are present in absorption (DOAS) measurements above the ocean and insufficiently removed liquid water structures may interfere with trace gas absorptions leading to wrong (sometimes even non-physical) results. Currently available literature cross-sections of liquid water absorption are provided in coarser resolution than hyperspectral DOAS applications require and Vibrational Raman Scattering (VRS) is mostly unconsidered or compensated for using simulated pseudo cross-sections from radiative transfer modelling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS measurements were performed into very clear natural waters achieving underwater light paths of up to 50 m. From these measurements, the retrieval of a residual (H2Ores) spectrum is presented compensating simultaneously for insufficiencies of the liquid water absorption cross-section and broad-banded VRS structures. Small-banded (Ring) structures caused by VRS were found to be very efficiently compensated for by the intensity offset (straylight) correction included in the DOAS fit. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality. This was not achieved using a liquid water cross-section in combination with a simulated VRS spectrum. Typical values of improvement depend on the measurement's contamination with liquid water structures and range from ? 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ores spectrum was found to prevent misfits of NO2 slant columns especially for very low NO2 scenarios and thus increase the reliability of the fit. In test fits on OMI satellite data, the H2Ores spectrum was found selectively above ocean surfaces where it leads to fit quality improvements of up to 6-18%.

Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

2014-05-01

256

Isotopic mass-dependence of metal cation diffusion coefficients in liquid water  

SciTech Connect

Isotope distributions in natural systems can be highly sensitive to the mass (m) dependence of solute diffusion coefficients (D) in liquid water. Isotope geochemistry studies routinely have assumed that this mass dependence either is negligible (as predicted by hydrodynamic theories) or follows a kinetic-theory-like inverse square root relationship (D {proportional_to} m{sup -0.5}). However, our recent experimental results and molecular dynamics (MD) simulations showed that the mass dependence of D is intermediate between hydrodynamic and kinetic theory predictions (D {proportional_to} m{sup -{beta}} with 0 {<=} {beta} < 0.2 for Li{sup +}, Cl{sup -}, Mg{sup 2+}, and the noble gases). In this paper, we present new MD simulations and experimental results for Na{sup +}, K{sup +}, Cs{sup +}, and Ca{sup 2+} that confirm the generality of the inverse power-law relation D {proportional_to} m{sup -{beta}}. Our new findings allow us to develop a general description of the influence of solute valence and radius on the mass dependence of D for monatomic solutes in liquid water. This mass dependence decreases with solute radius and with the magnitude of solute valence. Molecular-scale analysis of our MD simulation results reveals that these trends derive from the exponent {beta} being smallest for those solutes whose motions are most strongly coupled to solvent hydrodynamic modes.

Bourg, I.C.; Richter, F.M.; Christensen, J.N.; Sposito, G.

2009-01-11

257

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

E-print Network

an instrument capable of measuring optical absorption independent of scattering effects. The measurement of optical absorption has always been complicated by scattering effects. The most common and perhaps simplest method of measuring absorption is based... Model V cross section parallel to the Z-axis . . 18 10 Model V cross section transverse to the Z-axis . 18 Absorption of Irgalan Black samples measured in a Cary 219 spectrophotometer. . . . . . . 19 12 Absorption vs the ratio (Sl/SO) at 630 nm...

Pope, Robin Merl

1990-01-01

258

A new model for the vertical spectral diffuse attenuation coefficient of downwelling irradiance in turbid coastal waters: validation with in situ measurements.  

PubMed

The vertical spectral diffuse attenuation coefficient of Kd is an important optical property related to the penetration and availability of light underwater, which is of fundamental interest in studies of ocean physics and biology. Models developed in the recent decades were mainly based on theoretical analyses and numerical (radiative transfer) simulations to estimate this property in optically deep waters, thus leaving inadequate knowledge of its variability at multiple depths and wavelengths, covering a wide range of solar incident geometry, in turbid coastal waters. In the present study, a new model is developed to quantify the vertical, spatial and temporal variability of K(d) at multiple wavelengths and to quantify its dependence with respect to solar incident geometry under differing sky conditions. Thus, the new model is derived as a function of inherent optical properties (IOPs - absorption a and backscattering b(b)), solar zenith angle and depth parameters. The model results are rigorously evaluated using time-series and discrete in situ data from clear and turbid coastal waters. The K(d) values derived from the new model are found to agree with measured data within the mean relative error 0.02~6.24% and R² 0.94~0.99. By contrast, the existing models have large errors when applied to the same data sets. Statistical results of the new model for the vertical spectral distribution of K(d) in clear oceanic waters (for different solar zenith and in-water conditions) are also good when compared to those of the existing models. These results suggest that the new model can provide an improved interpretation about the variation of the vertical spectral diffuse attenuation coefficient of downwelling irradiance, which will have important implications for ocean physics, biogeochemical cycles and underwater applications in both relatively clear and turbid coastal waters. PMID:24514558

Simon, Arthi; Shanmugam, Palanisamy

2013-12-01

259

State-of-the-Art Review on Crystallization Control Technologies for water/LiBr Absorption Heat Pumps  

SciTech Connect

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.

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

2011-01-01

260

NASA LASE water vapor differential absorption lidar measurements and performance evaluation  

Microsoft Academic Search

The Lidar Atmospheric Sensing Experiment (LASE) is a highly engineered and autonomous Differential Absorption Lidar (DIAL) system developed at NASA Langley Research Center (LaRC) to measure high-resolution water vapor and aerosol profiles in the troposphere. LASE is being developed as a precursor to the deployment of a spaceborne DIAL system for global measurement of high-resolution water vapor profiles. The LASE

S. Ismail; E. V. Browell

1995-01-01

261

Simultaneous mapping of absorption and scattering coefficients from a three-dimensional model of time-resolved optical tomography.  

PubMed

A Newton-Raphson inversion algorithm has been extended for simultaneous absorption and scattering reconstruction of fully three-dimensional (3D) diffuse optical tomographic imaging from time-resolved measurements. The proposed algorithm is derived from the efficient computation of the Jacobian matrix of the forward model and uses either the algebraic reconstruction technique or truncated singular-value decomposition as the linear inversion tool. Its validation was examined with numerically simulated data from 3-D finite-element discretization models of tissuelike phantoms, with several combinations of geometric and optical properties, as well as two commonly used source-detector configurations. Our results show that the fully 3-D image reconstruction of an object can be achieved with reasonable quality when volumetric light propagation in tissues is considered, and temporal information from the measurements can be effectively employed. Also, we investigated the conditions under which 3-D issues could be approximately addressed with two-dimensional reconstruction algorithms and further demonstrated that these conditions are seldom predictable or attainable in practice. Thus the application of 3-D algorithms to realistic situations is necessary. PMID:18354594

Gao, F; Poulet, P; Yamada, Y

2000-11-01

262

Towards the reanalysis of void coefficients measurements at proteus for high conversion light water reactor lattices  

SciTech Connect

High Conversion Light Water Reactors (HCLWR) allows a better usage of fuel resources thanks to a higher breeding ratio than standard LWR. Their uses together with the current fleet of LWR constitute a fuel cycle thoroughly studied in Japan and the US today. However, one of the issues related to HCLWR is their void reactivity coefficient (VRC), which can be positive. Accurate predictions of void reactivity coefficient in HCLWR conditions and their comparisons with representative experiments are therefore required. In this paper an inter comparison of modern codes and cross-section libraries is performed for a former Benchmark on Void Reactivity Effect in PWRs conducted by the OECD/NEA. It shows an overview of the k-inf values and their associated VRC obtained for infinite lattice calculations with UO{sub 2} and highly enriched MOX fuel cells. The codes MCNPX2.5, TRIPOLI4.4 and CASMO-5 in conjunction with the libraries ENDF/B-VI.8, -VII.0, JEF-2.2 and JEFF-3.1 are used. A non-negligible spread of results for voided conditions is found for the high content MOX fuel. The spread of eigenvalues for the moderated and voided UO{sub 2} fuel are about 200 pcm and 700 pcm, respectively. The standard deviation for the VRCs for the UO{sub 2} fuel is about 0.7% while the one for the MOX fuel is about 13%. This work shows that an appropriate treatment of the unresolved resonance energy range is an important issue for the accurate determination of the void reactivity effect for HCLWR. A comparison to experimental results is needed to resolve the presented discrepancies. (authors)

Hursin, M.; Koeberl, O.; Perret, G. [Paul Scherrer Institut PSI, 5232 Villigen (Switzerland)

2012-07-01

263

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)

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.

Sudan Acharya, Madhu; Rauchecker, Markus; Wu, Wei

2014-05-01

264

Mapping Canadian boreal forest vegetation using pigment and water absorption features derived from the AVIRIS sensor  

Microsoft Academic Search

Using imagery of the Canadian boreal forest, we explored the ability of the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) to map vegetation type by taking advantage of pigment and water absorption features. Two techniques were exploited. In the first classification routine, laboratory-acquired leaf spectra representing different \\

David A. Fuentes; John A. Gamon; Hong-Lie Qiu; Daniel A. Sims; Dar A. Roberts

2001-01-01

265

Ammonia absorption from a bubble expanding at a submerged orifice into water  

Microsoft Academic Search

To investigate the mechanism of gas absorption from a bubble containing soluble and insoluble components, a gaseous mixture of ammonia and nitrogen was bubbled into water. The growth curve, volume, surface area and shape of the growing bubbles were measured with parameters such as inlet gas composition, gas flow rate and gas chamber volume. The bubble volume decreased with the

Koichi Terasaka; Junko Oka; Hideki Tsuge

2002-01-01

266

Forest structure and biomass estimates derived from red edge and water absorption geometry using AVIRIS data  

Microsoft Academic Search

Geometric analysis of spectral signatures collected from known forest sites using narrow spectral bands in the red-edge and five water absorption regions are the basis for developing ratios to estimate forest biomass and canopy structure. The study area used to test the methodology was located within Congaree Swamp National Monument in central South Carolina. This is one of the oldest

Nelson Wellausen Dias

2001-01-01

267

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...

268

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

NASA Astrophysics Data System (ADS)

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.

Kiatkamjornwong, Suda; Chomsaksakul, Wararuk; Sonsuk, Manit

2000-10-01

269

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

E-print Network

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...

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

2009-02-26

270

Linear and nonlinear optical absorption coefficients and refractive index changes in modulation-doped quantum wells: Effects of the magnetic field and hydrostatic pressure  

NASA Astrophysics Data System (ADS)

In this study, the linear, the third-order nonlinear and total optical absorption coefficients and refractive index changes of a modulation-doped GaAs/AlxGaAs quantum well are investigated numerically. In the effective-mass approximation, the electronic structure of modulation-doped quantum well is calculated by solving the Schrödinger and Poisson equations self-consistently. Optical properties are obtained using the compact density matrix approach. The effects of structure parameters, the applied magnetic field and the hydrostatic pressure on the optical properties of the modulation-doped quantum well are studied. Results show that the resonant peaks shift toward the higher (lower) energies with the increase in the magnetic field (pressure). The magnitude of the resonant peaks of the optical properties decreases with the increasing magnetic field or pressure.

Nazari, M.; Karimi, M. J.; Keshavarz, A.

2013-11-01

271

Laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 microm) and ultraviolet (300-350 nm) spectral regions.  

PubMed

For the measurement of atmospheric ozone concentrations, the mid-infrared and ultraviolet regions are both used by ground-, air-, or satellite-borne instruments. In this study we report the first laboratory intercomparison of the ozone absorption coefficients using simultaneous measurements in these spectral regions. The intercomparison shows good agreement (around 98.5%) between the HITRAN 2000 recommendation for the mid-infrared and the most reference measurements in the ultraviolet regions, whereas systematic differences of about 5.5% are observed when using the recommendation of HITRAN2003 for the mid-infrared. Possible reasons for this discrepancy are discussed. Future measurements are clearly needed to resolve this issue. PMID:16833407

Picquet-Varrault, B; Orphal, J; Doussin, J-F; Carlier, P; Flaud, J-M

2005-02-17

272

Predicting inhomogeneous water absorption in an ionic diblock polymer membrane  

NASA Astrophysics Data System (ADS)

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.

Herbst, Daniel; Witten, Thomas

2013-03-01

273

Extension of the Inverse Adding-Doubling Method to the Measurement of Wavelength-Dependent Absorption and Scattering Coefficients of Biological Samples  

SciTech Connect

Light interaction with biological tissue can be described using three parameters: the scattering and absorption coefficients (us and ua), as well as the anisotropy (g) which describes the directional dependence of the scattered photons. Accurately determining these optical properties for different tissue types at specific wavelengths, and simultaneously, would be beneficial for a variety of different biomedical applications. The goal of this project was to take a user-defined g-value and determine the remaining two parameters for a specified wavelength range for an integrating sphere with a collimated white light input source system. A fully automated computer program and process was developed to collect data for all wavelengths in a timely and accurate manner. LabVIEW was used to write programs to automate: raw intensity data collection from a spectrometer equipped integrating sphere, conversion of the data into a format for analysis via Scott Prahl's Inverse Adding-Doubling (IAD) C code execution, and computation of the optical properties based on the output from the IAD code. To allow data to be passed efficiently between LabVIEW and C code program modules, the two were combined into a single program (OPT 3.1). OPT 3.1 was tested using tissue mimicking phantoms and determination of the absorption and scattering coefficients showed excellent agreement with theory for wavelengths were the user inputted single g-value was sufficiently precise. Future improvements entail providing for multi-wavelength g-value entry to extend the accuracy of results to encompass the complete system multispectral range. Ultimately, the data collection process and algorithms developed through this effort will be used to study actual biological tissues for the purpose of deriving and refining models for light-tissue interactions.

Baba, Justin S [ORNL; Allegood, Marcus S [ORNL

2008-01-01

274

Activity coefficients of NaCl in trehalose-water and maltose-water mixtures at 298.15 K.  

PubMed

The ionic mean activity coefficients of NaCl in trehalose-water and maltose-water mixtures have been experimentally determined at 298.15 K from emf measurements by electrochemical cell containing ion selective electrodes (ISE): Na-ISE/NaCl (m), sugar (Y%), H(2)O (100-Y%)/Cl-ISE. The electrolyte molality (m) ranged between 0.01 and 3 mol kg(-1), approximately, and the weight percent (Y%) of sugar in the mixture of solvents between 0, 10, 20, 30 and 40%. The system is considered as an electrolyte in a mixture of solvents and the data have been analysed by using the Debye-Hückel and Pitzer equations. The results obtained with both equations are in quite agreement with each other. The variation of the fit parameter from both equations were studied relative to the change in the dielectric properties of the mixture of solvents. Standard free energy of transference were comparatively discussed in terms of ion-solvent, ion-ion interactions and the hydration of both the electrolyte and the sugar. PMID:12801715

Hernández-Luis, Felipe; Amado-González, Eliseo; Esteso, Miguel A

2003-06-23

275

Measurement of mass attenuation coefficients in some Cr, Co and Fe compounds around the absorption edge and the validity of the mixture rule  

NASA Astrophysics Data System (ADS)

The total mass attenuation coefficients for elements Cr, Co and Fe and compounds CrCl_{2}, CrCl_{3}, Cr_{2}(SO_{4})_{3}K_{2}SO_{4}\\cdot24H_{2}O, CoO, CoCl_{2}, Co(CH_{3}COO)_{2}, FePO_{4}, FeCl_{3}\\cdot6H_{2}O, Fe(SO_{4})_{2}NH_{4}\\cdot12H_{2}O were measured at different energies between 4.508 and 14.142 keV using secondary excitation method. Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr were chosen as secondary exciters. 59.5 keV ?-rays emitted from a ^{241}Am annular source were used to excite a secondary exciter and K_{?}(K-L_{3}, L_{2}) lines emitted by the secondary exciter were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. It was observed that mixture rule method is not a suitable method for determination of the mass attenuation coefficients of compounds, especially at an energy that is near the absorption edge. The obtained values were compared with theoretical values.

Turgut, U.; Simsek, O.; Büyükkasap, E.

2007-08-01

276

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

E-print Network

, the low COP of the absorption machine was limited seriously to compete with the refrigeration machine that is drove by electricity. Therefore, most researchers focus their attention on the improvement of performance of the absorption system through many...

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

2006-01-01

277

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

NASA Astrophysics Data System (ADS)

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.

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

278

Differential absorption lidar measurements of atmospheric water vapor using an optical parametric oscillator source.  

PubMed

A differential absorption lidar system based on a continuously tunable Nd:YAG pumped optical parametric oscillator source is described which is capable of range-resolved measurements of atmospheric species with absorption bands in the 1.4-4.0-mum range. The system has been used to measure atmospheric water vapor at ranges of up to 1 km. The actual and predicted performances of the system are compared, and some of the problems peculiar to continuously tunable IR sources, such as non-negligible linewidth and the need for accurate wavelength setting, are analyzed. PMID:20401088

Brassington, D J

1982-12-15

279

Zone fluidics for measurement of octanol-water partition coefficient of drugs.  

PubMed

A novel zone fluidics (ZF) system for the determination of the octanol-water partition coefficient (Pow) of drugs was developed. The ZF system consisted of a syringe pump with a selection valve, a holding column, a silica capillary flow-cell and an in-line spectrophotometer. Exact microliter volumes of solvents (octanol and phosphate buffer saline) and a solution of the drug, sandwiched between air segments, were sequentially loaded into the vertically aligned holding column. Distribution of the drug between the aqueous and octanol phases occurred by the oscillation movement of the syringe pump piston. Phase separation occurred due to the difference in densities. The liquid zones were then pushed into the detection flow cell. In this method, absorbance measurements in only one of the phase (octanol or aqueous) were employed, which together with the volumes of the solvents and pure drug sample, allowed the calculation of the Pow. The developed system was applied to the determination of the Pow of some common drugs. The log (Pow) values agreed well with a batch method (R(2)=0.999) and literature (R(2)=0.997). Standard deviations for intra- and inter-day analyses were both less than 0.1log unit. This ZF system provides a robust and automated method for screening of Pow values in the drug discovery process. PMID:25682240

Wattanasin, Panwadee; Saetear, Phoonthawee; Wilairat, Prapin; Nacapricha, Duangjai; Teerasong, Saowapak

2015-02-20

280

Spreading waves of a reduced diffusion coefficient of water in normal and ischemic rat brain.  

PubMed

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. In all animals in which potassium chloride or the needle stab was applied, a region of decreased ADC values to a mean of 0.45 +/- 0.03 x 10(-5)cm2/s occurred. These reduced ADC levels appeared in the posterior parietal cortex within 1 min after cortical stimulation and the change recovered within 1 min. Then a ripple-like movement of similar changes developed across the unilateral cortex. This change was localized to the cortex and no significant ADC changes occurred in subcortical structures. The propagating speed of this movement was 3.4 +/- 0.5 mm/min. These findings are compatible with spreading depression as observed electrophysiologically. Similar ADC changes occurred in areas distinct from the ischemic lesion in 3 of 12 animals subjected to focal cerebral ischemia. This magnetic resonance method could detect spreading ADC decline if it occurred in human diseases including brain ischemia. PMID:7860651

Hasegawa, Y; Latour, L L; Formato, J E; Sotak, C H; Fisher, M

1995-03-01

281

Trophic magnification of PCBs and Its relationship to the octanol-water partition coefficient.  

PubMed

We investigated polychlorinated biphenyl (PCB) bioaccumulation relative to octanol-water partition coefficient (K(OW)) and organism trophic position (TP) at the Lake Hartwell Superfund site (South Carolina). We measured PCBs (127 congeners) and stable isotopes (?¹?N) in sediment, organic matter, phytoplankton, zooplankton, macroinvertebrates, and fish. TP, as calculated from ?¹?N, was significantly, positively related to PCB concentrations, and food web trophic magnification factors (TMFs) ranged from 1.5-6.6 among congeners. TMFs of individual congeners increased strongly with log K(OW), as did the predictive power (r²) of individual TP-PCB regression models used to calculate TMFs. We developed log K(OW)-TMF models for eight food webs with vastly different environments (freshwater, marine, arctic, temperate) and species composition (cold- vs warmblooded consumers). The effect of K(OW) on congener TMFs varied strongly across food webs (model slopes 0.0-15.0) because the range of TMFs among studies was also highly variable. We standardized TMFs within studies to mean = 0, standard deviation (SD) = 1 to normalize for scale differences and found a remarkably consistent K(OW) effect on TMFs (no difference in model slopes among food webs). Our findings underscore the importance of hydrophobicity (as characterized by K(OW)) in regulating bioaccumulation of recalcitrant compounds in aquatic systems, and demonstrate that relationships between chemical K(OW) and bioaccumulation from field studies are more generalized than previously recognized. PMID:21466215

Walters, David M; Mills, Marc A; Cade, Brian S; Burkard, Lawrence P

2011-05-01

282

Determination of traces of silver in waters by anion exchange and atomic absorption spectrophotometry  

USGS Publications Warehouse

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.

Chao, T.T.; Fishman, M.J.; Ball, J.W.

1969-01-01

283

Capacity for Absorption of Water-Soluble Secondary Metabolites Greater in Birds than in Rodents  

PubMed Central

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

Karasov, William H.; Caviedes-Vidal, Enrique; Bakken, Bradley Hartman; Izhaki, Ido; Samuni-Blank, Michal; Arad, Zeev

2012-01-01

284

Estimation of octanol/water partition coefficient and aqueous solubility of environmental chemicals using molecular fingerprints and machine learning methods  

EPA Science Inventory

Octanol/water partition coefficient (logP) and aqueous solubility (logS) are two important parameters in pharmacology and toxicology studies, and experimental measurements are usually time-consuming and expensive. In the present research, novel methods are presented for the estim...

285

Grapevine water use and the crop coefficient are linear functions of the shaded area measured beneath the canopy  

Microsoft Academic Search

The relationships among water use and the crop coefficient of Vitis vinifera L. cv. Thompson Seedless with several measures of canopy development were determined with the aid of a weighing lysimeter in the San Joaquin Valley of California. At various times during two growing seasons, vine leaf area, calculated leaf area index (LAI) and the amount of shade cast on

L. E. Williams; J. E. Ayars

2005-01-01

286

USING A SUBSURFACE DRIP IRRIGATION SYSTEM TO MEASURE CROP COEFFICIENTS AND WATER USE OF COWPEA (VIGNA UNGUICULATA).  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop coefficients and water use by CB46 cowpea were measured using the same field and the same "slope" procedure developed and published for cotton, using a highly-efficient subsurface drip irrigation system on sandy soil at the University of California Shafter Research and Extension Center, near Sh...

287

A yearlong study of water-soluble organic carbon in Beijing II: Light absorption properties  

NASA Astrophysics Data System (ADS)

Light absorption properties of water-soluble organic carbon (WSOC) in Beijing were investigated by 24 h-averaged fine particulate matter (PM2.5) samples collected from October 2010 to November 2011. The light absorption spectra of WSOC exhibited strong wavelength dependence such that the absorption Ångstrom exponent was approximately 7.5. The light absorption at 365 nm (Abs365), which is typically used as a proxy of water-soluble brown carbon, was found to correlate strongly with WSOC (R2 > 0.75, p < 0.01). Moreover, the correlation between Abs365 and levoglucosan (especially in fall and winter) indicated that biomass burning could contribute significantly to water-soluble brown carbon. Source apportionment with Positive Matrix Factorization (PMF) model showed that biomass burning and mixed sources contributed 58.0% and 20.8% to total Abs365, compared with 21.2% from WSOC associated with sulfate and oxalate. The mass absorption efficiency (MAE) of WSOC in Beijing showed distinct temporal variations (averaging 1.26 m2/g and 0.51 m2/g during winter and summer, respectively), and was approximately 2-3 times the values of that observed in the southeastern United States, but was substantially lower than the summertime results from Los Angeles. Influence factors responsible for the temporal and spatial variations of MAE were investigated. MAE were calculated for each PMF factor. It was found that the MAE for WSOC from biomass burning (1.19 m2/g) and mixed primary sources (2.89 m2/g) was much higher than that of WSOC associated with sulfate or oxalate (0.32-0.33 m2/g) in Beijing. In addition, it was concluded that differences in the precursors of WSOC might also be responsible for the observed variation of MAE such that WSOC associated with anthropogenic precursors are more light-absorbing compared with WSOC biogenic sources.

Du, Zhenyu; He, Kebin; Cheng, Yuan; Duan, Fengkui; Ma, Yongliang; Liu, Jiumeng; Zhang, Xiaolu; Zheng, Mei; Weber, Rodney

2014-06-01

288

Influence of molecular weight on oral absorption of water soluble chitosans.  

PubMed

Chitosan, a cationic polysaccharide, has been widely employed as dietary supplement and in pharmacological and biomedical applications. Although numerous studies have focused on its applications as pharmaceutical excipients or bioactive reagents, molecular weight (MW)-dependent pharmaceutical and bioactive properties remain unclear. As a preliminary study, we investigated the MW-dependent Caco-2 cell layer transport phenomena (in vitro) and intestinal absorption patterns after oral administration (in vivo) of water-soluble chitosans (WSCs). The absorption of chitosan was significantly influenced by its MW. As the MW increases, the absorption decreases. Compared to high-MW chitosan (WSC 230K, MW=230 kDa), absorption profiles were observed to increase more than 23 and 25 times with WSC 3.8K (MW=3.8 kDa) in both in vitro and in vivo transport experiments, respectively. Furthermore, the chitosans showed concentration- and MW-dependent cytotoxic effects, and the chitosan oligosaccharides (MW<10 kDa) showed negligible cytotoxic effect on the Caco-2 cells. In consideration with safety and absorption profiles, chitosan oligosaccharides may be considered as safe and potential candidates for pharmaceutical and biomedical applications. PMID:15653159

Chae, Su Young; Jang, Mi-Kyeong; Nah, Jae-Woon

2005-02-01

289

Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet  

NASA Astrophysics Data System (ADS)

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.

Fraine, Jonathan; Deming, Drake; Benneke, Bjorn; Knutson, Heather; Jordán, Andrés; Espinoza, Néstor; Madhusudhan, Nikku; Wilkins, Ashlee; Todorov, Kamen

2014-09-01

290

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

SciTech Connect

This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose of this work was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. PNL researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH{sub 4}{sup +}). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

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

1995-05-01

291

Water vapor heterogeneity related to tropopause folds over the North Atlantic revealed by airborne water vapor differential absorption lidar  

Microsoft Academic Search

Airborne differential absorption lidar (DIAL) measurements of tropospheric water vapor and aerosol\\/clouds are presented from transfers across the North Atlantic on 13-15 May and 16-18 June 2002. The intense dynamical activity over the Atlantic is reflected in complex structures like deep tropopause folds, extended dry layers, and tilted aerosol filaments. Intrusions with H2O mixing ratios below 0.03 g kg-1 regularly

H. Flentje; A. Dörnbrack; G. Ehret; A. Fix; C. Kiemle; G. Poberaj; M. Wirth

2005-01-01

292

Water vapor heterogeneity related to tropopause folds over the North Atlantic revealed by airborne water vapor differential absorption lidar  

Microsoft Academic Search

Airborne differential absorption lidar (DIAL) measurements of tropospheric water vapor and aerosol\\/clouds are presented from transfers across the North Atlantic on 13–15 May and 16–18 June 2002. The intense dynamical activity over the Atlantic is reflected in complex structures like deep tropopause folds, extended dry layers, and tilted aerosol filaments. Intrusions with H2O mixing ratios below 0.03 g kg?1 regularly

H. Flentje; A. Dörnbrack; G. Ehret; A. Fix; C. Kiemle; G. Poberaj; M. Wirth

2005-01-01

293

Measurement of Rn-222 in water by absorption in polycarbonates and liquid scintillation counting  

NASA Astrophysics Data System (ADS)

This work presents a new technique for measurement of activity concentrations of Rn-222 in water which is based on liquid scintillation counting (LSC) of polycarbonates exposed in the water. The polycarbonate material has high absorption ability to radon and when exposed in a radon-containing environment (air or water), it absorbs and concentrates radon in its volume. This property of the polycarbonate material is used for sampling 222Rn from the water. The main new element in this work is that it proposes the LSC technique for measurement of the radiation, emitted from the polycarbonate material. This radiation is due to the decay of the absorbed 222Rn and its progeny. Experimental results of LSC of polycarbonate granules and thin foils exposed in water with different activity concentrations of Rn-222 are presented. In all cases a very good linear correlation between the LS counting rate and the activity concentration of the water is found. The LSC of polycarbonates shows similar or even higher sensitivity in comparison to that of LSC of water. The estimated radon-in-water minimal detectable activity concentrations of the proposed method are similar or lower than those of the LSC and lower than those obtained by gamma spectrometry. The proposed method is simple, robust, inexpensive and avoids the need of taking water samples for laboratory analysis. It facilitates studies of the spatial distribution of 222Rn in water basins by exposure of polycarbonate specimens at different spots or depths and subsequent liquid scintillation counting.

Mitev, K.; Dimitrova, I.; Zhivkova, V.; Georgiev, S.; Gerganov, G.; Pressyanov, D.; Boshkova, T.

2012-06-01

294

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

USGS Publications Warehouse

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.

Lee, M.W.

2006-01-01

295

Preliminary measurements with an automated compact differential absorption lidar for the profiling of water vapor.  

PubMed

The design and preliminary tests of an automated differential absorption lidar (DIAL) that profiles water vapor in the lower troposphere are presented. The instrument, named CODI (for compact DIAL), has been developed to be eye safe, low cost, weatherproof, and portable. The lidar design and its unattended operation are described. Nighttime intercomparisons with in situ sensors and a radiosonde are shown. Desired improvements to the lidar, including a more powerful laser, are also discussed. PMID:15176200

Machol, Janet L; Ayers, Tom; Schwenz, Karl T; Koenig, Keith W; Hardesty, R Michael; Senff, Christoph J; Krainak, Michael A; Abshire, James B; Bravo, Hector E; Sandberg, Scott P

2004-05-20

296

Bradykinin B2 receptor antagonist increases chloride and water absorption in rat medullary collecting duct.  

PubMed

This study tested the hypothesis that intrarenal kinins play a regulatory role in electrolyte excretion by altering Cl- absorption in the collecting duct. We measured Cl- and insulin concentrations in tubular fluid samples obtained from medullary collecting ducts (MCD) of Dahl/Rapp salt-resistant (SR/ Jr) rats by microcatheterization of ducts of Bellini before and after treatment with the bradykinin receptor antagonist HOE-140. Tubular fluid was obtained from paired terminal inner medullary (t-IMCD) and outer medullary (OMCD) collecting duct sites of the left kidney. HOE-140 (n = 7) or vehicle (n = 5) was infused intravenously, and the collections were repeated. HOE-140 did not alter glomerular filtration rate but decreased urine flow rate (P < 0.05) and absolute and fractional Cl- excretion (P < 0.01). HOE-140 did not alter the fraction of filtered Cl- delivered (FDCl) to the OMCD but decreased FDCl to the t-IMCD from 2.3 +/- 0.3 to 1.3 +/- 0.3% (P < 0.05). The fraction of filtered Cl- absorbed per millimeter between the collection sites was increased from 0.2 +/- 0.1 to 0.6 +/- 0.1% (P < 0.05). Fractional absorption of water along the MCD was also increased (P < 0.05). No changes in excretory function or tubular Cl- or water absorption were observed in vehicle-treated rats. These studies show that kinin B2 receptor blockade enhances Cl- and water absorption in the MCD, a finding that supports a role of renal kinins in the regulation of NaCl and water excretion. PMID:8770134

Mukai, H; Fitzgibbon, W R; Bozeman, G; Margolius, H S; Ploth, D W

1996-08-01

297

Comparative simulation and investigation of ammonia-water: absorption cycles for heat pump applications  

Microsoft Academic Search

Several recent programs in absorption research have focused on technology for domestic heating and cooling utilizing natural gas. In residential and small commercial size applications, ammonia-water cycles offer the possibility of a gas-fired heat pump for both winter heating and summer cooling, at better year-round COPS than currently available by various alternatives. Several cycles have been considered for this purpose,

M Engler; G Grossman; H.-M Hellmann

1997-01-01

298

Airborne remote sensing of tropospheric water vapor with a near-infrared differential absorption lidar system.  

PubMed

A near-infrared airborne differential absorption lidar (DIAL) system has become operational. Horizontal and vertical water vapor profiles of the troposphere during summer (nighttime) conditions extending from the top of the planetary boundary layer (PBL) up to near the tropopause are investigated. These measurements have been performed in Southern Bavaria, Germany. The system design, the frequency control units, and an estimation of the laser line profile of the narrow-band dye laser are discussed. Effective absorption cross sections in terms of altitude are calculated. Statistical and systematic errors of the water vapor measurements are evaluated as a function of altitude. The effect of a systematic range-dependent error caused by molecular absorption is investigated by comparing the DIAL data with in situ measurements. Typical horizontal resolutions range from 4 km in the lower troposphere to 11 km in the upper troposphere, with vertical resolutions varying from 0.3 to 1 km, respectively. The lower limit of the sensitivity of the water vapor mixing ratio is calculated to be 0.01 g/kg. The total errors of these measurements range between 8% and 25%. A sine-shaped wave structure with a wavelength of 14 km and an amplitude of 20% of its mean value, detected in the lower troposphere, indicates an atmospheric gravity wave field. PMID:20830116

Ehret, G; Kiemle, C; Renger, W; Simmet, G

1993-08-20

299

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

PubMed Central

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

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

2012-01-01

300

Differential absorption and Raman lidar for water vapor profile measurements - A review  

NASA Technical Reports Server (NTRS)

Differential absorption lidar and Raman lidar have been applied to the range-resolved measurements of water vapor density for more than 20 years. Results have been obtained using both lidar techniques that have led to improved understanding of water vapor distributions in the atmosphere. This paper reviews the theory of the measurements, including the sources of systematic and random error; the progress in lidar technology and techniques during that period, including a brief look at some of the lidar systems in development or proposed; and the steps being taken to improve such lidar systems.

Grant, William B.

1991-01-01

301

Automated atomic absorption spectrometric determination of total arsenic in water and streambed materials  

USGS Publications Warehouse

An automated method to determine both inorganic and organic forms of arsenic In water, water-suspended mixtures, and streambed materials Is described. Organic arsenic-containing compounds are decomposed by either ultraviolet radiation or by suHurlc acid-potassium persulfate digestion. The arsenic liberated, with Inorganic arsenic originally present, is reduced to arsine with sodium borohydrlde. The arable Is stripped from the solution with the aid of nitrogen and Is then decomposed In a tube furnace heated to 800 ??C which Is placed in the optical path of an atomic absorption spectrometer. Thirty samples per hour can be analyzed to levels of 1 ??g arsenic per liter.

Fishman, M.

1977-01-01

302

Water vapor absorption spectra of the upper atmosphere /45-185 per cm/  

NASA Technical Reports Server (NTRS)

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.-

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

1975-01-01

303

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

PubMed

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

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

1975-09-01

304

In-Line Capacitance Sensor for Real-Time Water Absorption Measurements  

NASA Technical Reports Server (NTRS)

A capacitance/dielectric sensor was designed, constructed, and used to measure in real time the in-situ water concentration in a desiccant water bed. Measurements were carried out with two experimental setups: (1) passing nitrogen through a humidity generator and allowing the gas stream to become saturated at a measured temperature and pressure, and (2) injecting water via a syringe pump into a nitrogen stream. Both water vapor generating devices were attached to a downstream vertically-mounted water capture bed filled with 19.5 g of Moisture Gone desiccant. The sensor consisted of two electrodes: (1) a 1/8" dia stainless steel rod placed in the middle of the bed and (2) the outer shell of the stainless steel bed concentric with the rod. All phases of the water capture process (background, heating, absorption, desorption, and cooling) were monitored with capacitance. The measured capacitance was found to vary linearly with the water content in the bed at frequencies above 100 kHz indicating dipolar motion dominated the signal; below this frequency, ionic motion caused nonlinearities in the water concentration/capacitance relationship. The desiccant exhibited a dielectric relaxation whose activation energy was lowered upon addition of water indicating either a less hindered rotational motion or crystal reorientation.

Nurge, Mark A.; Perusich, Stephen A.

2010-01-01

305

Protein-water network dynamics during metalloenzyme hydrolysis observed by kinetic THz absorption (KITA)  

NASA Astrophysics Data System (ADS)

For long, the contribution of water network motions to enzymatic reactions was enigmatic due to the complexity of biological systems and to experimental limitations. Thanks to the development of new powerful THz emitters and detectors in the last decades, it is now possible to probe dynamics on the timescale of the fast hydrogen bond rearrangements during biochemical reactions. For this purpose, we developed a kinetic terahertz absorption (KITA) spectrometer which combines the strength of THz radiation (~1012 Hz = 1 ps) to directly probe collective picosecond protein-water dynamics with the fast mixing properties of a stopped-flow apparatus which initializes a biochemical reaction within milliseconds. With KITA, we analyzed the collective water dynamics during substrate hydrolyses by a human matrix-metalloproteinase. In addition, we studied the reorganization and electrostatic changes at the catalytic zinc-ion from the enzyme active site and performed molecular dynamics simulations of the enzyme-substrate-water system. Our results revealed a systematic gradient of water network motions: From the active site to the bulk water hydrogen bond dynamics increased from 7 ps (active site) to 1ps (bulk water) prior to substrate binding and hydrolysis. The approaching substrate perturbs the dynamic water gradient resulting in an overshoot of KITA signal which then relaxes back during onset of substrate hydrolyses. Our findings suggest that collective water dynamics may contribute to effective substrate binding to enzyme active sites and could be induced by the charge of the catalytic zinc-ion residing at the active site.

Born, Benjamin; Heyden, Matthias; Grossman, Moran; Sagi, Irit; Havenith, Martina

2013-02-01

306

Structural Change of the Mixtures of Ionic Liquid and Water Studied by Infrared Absorption Spectroscopy  

NASA Astrophysics Data System (ADS)

Infrared absorption spectra of the mixtures of ionic liquid and water (1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM]BF4) with varying concentrations were obtained by Attenuated Total Reflection (ATR) method. Investigation of the spectra in the OH-stretch vibration range indicated the structural change of the water with the change in the concentration. At very low concentration of water, two peaks around 3600cm-1 were assigned to the monomeric form of water molecules weakly hydrogen bonded to the BF4^- anions. With the increase in the water concentration, the broad feature at ˜3460cm-1 corresponding to the bulk water took over the above monomeric peaks, which gradually redshifted with the increased water concentration. In the range from 2800 to 3200cm-1 for the various CH-stretch vibration modes in the cation, the peaks in this ranged blueshifted with the increase in the water concentration. This blueshift was as much as ˜7cm-1 for the CH3 vibration modes of butyl chain while it hardly changed for the modes for the CH attached to the imidazolium core, suggesting varying degree of interactions between the carbon-bonded hydrogen and the water molecules.

Kim, Doseok; Jeon, Yoonnam; Sung, Jaeho; Ouchi, Yukio

2006-03-01

307

Strong water absorption in the dayside emission spectrum of the planet HD 189733b.  

PubMed

Recent observations of the extrasolar planet HD 189733b did not reveal the presence of water in the emission spectrum of the planet. Yet models of such 'hot-Jupiter' planets predict an abundance of atmospheric water vapour. Validating and constraining these models is crucial to understanding the physics and chemistry of planetary atmospheres in extreme environments. Indications of the presence of water in the atmosphere of HD 189733b have recently been found in transmission spectra, where the planet's atmosphere selectively absorbs the light of the parent star, and in broadband photometry. Here we report the detection of strong water absorption in a high-signal-to-noise, mid-infrared emission spectrum of the planet itself. We find both a strong downturn in the flux ratio below 10 microm and discrete spectral features that are characteristic of strong absorption by water vapour. The differences between these and previous observations are significant and admit the possibility that predicted planetary-scale dynamical weather structures may alter the emission spectrum over time. Models that match the observed spectrum and the broadband photometry suggest that heat redistribution from the dayside to the nightside is weak. Reconciling this with the high nightside temperature will require a better understanding of atmospheric circulation or possible additional energy sources. PMID:19079054

Grillmair, Carl J; Burrows, Adam; Charbonneau, David; Armus, Lee; Stauffer, John; Meadows, Victoria; van Cleve, Jeffrey; von Braun, Kaspar; Levine, Deborah

2008-12-11

308

Intersubband optical absorption coefficients and refractive index changes in a graded quantum well under intense laser field: Effects of hydrostatic pressure, temperature and electric field  

NASA Astrophysics Data System (ADS)

The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga0.7Al0.3As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga0.7Al0.3As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications.

Ungan, F.; Restrepo, R. L.; Mora-Ramos, M. E.; Morales, A. L.; Duque, C. A.

2014-02-01

309

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

NASA Astrophysics Data System (ADS)

The K-shell absorption jump factors and jump ratios were derived from new mass attenuation coefficients measured using an energy dispersive X-ray fluorescence (EDXRF) spectrometer for Tm, Yb elements being Tm 2O 3, Yb 2O 3 compounds and pure Lu, Hf, Ta, W, Re and Os. The measurements, in the region 56-77 keV, were done in a transmission geometry utilizing the K ?1 , K ?2 , K ?1 and K ?2 X- rays from different secondary source targets (Yb, Ta, Os, W, Re and Ir, etc.) excited by the 123.6 keV ?-photons from an 57Co annular source and detected by an Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values. The measured values of Tm, Yb, Lu, Hf, Ta, W, Re and Os are reported here for the first time.

Kaya, Necati; T?ra?o?lu, Engin; Apayd?n, Gökhan; Ayl?kc?, Volkan; Cengiz, Erhan

2007-08-01

310

ISO-SWS observations of pure rotational water absorption lines toward Orion-IRc2  

E-print Network

First detections of thermal water vapor absorption lines have been made toward Orion IRc2 using the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). Grating spectra covering wavelengths 25-45 micron yield 19 pure rotational lines, originating from energy levels 200-750 K above ground. Fabry-Perot spectra of 5 transitions resolve the line profiles and reveal the water gas kinematics. The fact that all lines are seen in absorption is in striking contrast with data from the ISO Long Wavelength Spectrometer (LWS), where the water lines appear in emission. At least one line displays a P-Cygni type profile, which suggests that the water is located in an expanding shell centered on or near IRc2. The expansion velocity is 18 km per second, in agreement with the value inferred from water maser observations by Genzel et al. (1981). Because the continuum is intense and likely formed in or near the water-containing gas, the excitation of the observed transitions is dominated by radiative processes. A simple, generalised curve-of-growth method is presented and used to analyze the data. A mean excitation temperature of 72 K and a total water column density of 1.5e18 molecules per cm squared are inferred, each with an estimated maximum uncertainty of 20%. Combined with the molecular hydrogen column density derived from ISO observations of the pure rotational lines, and an assumed temperature of 200-350 K, the inferred water abundance is 2e-4 to 5e-4 in the warm shocked gas. This abundance is similar to that found recently by Harwit et al. (1998) toward Orion using data from the LWS, but higher than that found for most other shocked regions by, for example, Liseau et al. (1996).

C. M. Wright; E. F. van Dishoeck; J. H. Black; H. Feuchtgruber; J. Cernicharo; E. Gonzalez-Alfonso; Th. de Graauw

2000-04-07

311

H + O3 Fourier-transform infrared emission and laser absorption studies of OH(X2Pi) radical - An experimental dipole moment function and state-to-state Einstein A coefficients  

NASA Technical Reports Server (NTRS)

FTIR emission/absorption spectroscopy is used to measure the relative intensities of 88 pairs of rovibrational transitions of OH(X2Pi) distributed over 16 vibrational bands. The experimental technique used to obtain the Einstein A ratios is discussed. The dipole moment function which follows from the intensity ratios along with Einstein A coefficients calculated from mu(r) is presented.

Nelson, David D., Jr.; Schiffman, Aram; Nesbitt, David J.; Orlando, John J.; Burkholder, James B.

1990-01-01

312

Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols.  

PubMed

An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H(2)O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and > 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H(2)O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H(2)O absorption-line parameters were perfo med to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H(2)O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H(2)O radiosondes. The H(2)O distributions measured with the DIAL system differed by ? 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions. PMID:20941181

Higdon, N S; Browell, E V; Ponsardin, P; Grossmann, B E; Butler, C F; Chyba, T H; Mayo, M N; Allen, R J; Heuser, A W; Grant, W B; Ismail, S; Mayor, S D; Carter, A F

1994-09-20

313

A study of water vapor absorption at CO2 laser frequencies using a differential spectrophone and white cell  

Microsoft Academic Search

Water vapor absorption at CO2 laser frequencies has been studied using a differential spectrophone and a long path multiple traversal cell. The results of these measurements have been analyzed in terms of the Lorentz line shape and the far wing model for continuum absorption in the 9-10 micrometers wavelength region. An electronically stabilized, grating tunable cw CO2 laser with a

J. C. Peterson

1978-01-01

314

Measurement of attenuation coefficients for bone, muscle, fat and water at 140, 364 and 662 keV ?-ray energies  

NASA Astrophysics Data System (ADS)

The half-value thicknesses, linear and mass attenuation coefficients of biological samples such as bone, muscle, fat and water have been measured at 140, 364 and 662 keV ?-ray energies by using the ATOMLABTM-930 medical spectrometer. The ?-rays were obtained from 99mTc, 131I and 137Cs ?-ray point sources. Also theoretical calculations have been performed in order to obtain the half-value thicknesses and, mass and linear attenuation coefficients at photon energies 0.001 keV 20 MeV for bone, muscle and water samples. The calculated value and the experimental results of this work and the other results in literature are found to be in good agreement.

Akar, A.; Balta?, H.; Çevik, U.; Korkmaz, F.; Okumu?o?lu, N. T.

2006-11-01

315

Atmospheric water vapor differential absorption measurements on vertical paths with a CO2 lidar.  

PubMed

Ground based vertical path differential absorption measurements were obtained up to a height of 1.5 km with a CO2 lidar transmitting alternatively on the R(20) (10.247-microm) and R(18) (10.260-microm) lines during daylight in conditions of both strong and weak temperature inversions. The differential absorption between these lines for typical middle latitude lower atmosphere water vapor concentrations appears to be well suited to this type of measurement as the power loss on the more absorbed backscattered line [R(20)] is not too great as to unduly restrict the operating range, while the power differential is still sufficiently large to be readily measureable. In one set of measurements a strong temperature inversion at a height of 1 km resulted in a rapid vertical lapse in aerosol concentration with a consequent loss of SNR on the returns and severe distortion to the differential absorption profiles at this level. Water vapor profiles were derived from all measurements except in the region of the strong temperature inversion where the atmospheric backscattering cross section decayed rapidly. Reasonable results were obtained through the weak inversion region. The measurement capability of the lidar was found to be restricted by the length of the laser pulse tail and an inadequate signal-to-noise performance in regions of strong temperature inversions due to the associated decreases in aerosol concentration. PMID:18196122

Baker, P W

1983-08-01

316

Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region.  

PubMed

Recently measured properties of water vapor (H(2)O) absorption lines have been used in calculations to evaluate the temperature sensitivity of differential absorption lidar (DIAL) H(2)O measurements. This paper estimates the temperature sensitivity of H(2)O lines in the 717-733-nm region for both H(2)O mixing ratio and number density measurements, and discusses the influence of the H(2)O line ground state energies E'', the H(2)O 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 sixty-seven H(2)O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E'' values in the 100-300-cm(-1) range were found to be optimum for DIAL measurements of H(2)O number densities, while E'' values in the 250-500-cm(-1) range were found to be optimum for H(2)O mixing ratio measurements. PMID:20700314

Browell, E V; Ismail, S; Grossmann, B E

1991-04-20

317

WATER ABSORPTION FROM GAS VERY NEAR THE MASSIVE PROTOSTAR AFGL 2136 IRS 1  

SciTech Connect

We present ground-based observations of the ?{sub 1} and ?{sub 3} fundamental bands of H{sub 2}O toward the massive protostar AFGL 2136 IRS 1, identifying absorption features due to 47 different ro-vibrational transitions between 2.468 ?m and 2.561 ?m. Analysis of these features indicates the absorption arises in warm (T = 506 ± 25 K), very dense (n(H{sub 2}) > 5 × 10{sup 9} cm{sup –3}) gas, suggesting an origin close to the central protostar. The total column density of warm water is estimated to be N(H{sub 2}O) = (1.02 ± 0.02) × 10{sup 19} cm{sup –2}, giving a relative abundance of N(H{sub 2}O)/N(H{sub 2}) ? 10{sup –4}. Our study represents the first extensive use of water vapor absorption lines in the near infrared, and demonstrates the utility of such observations in deriving physical parameters.

Indriolo, Nick; Neufeld, D. A. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Seifahrt, A. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Richter, M. J. [Department of Physics, University of California Davis, Davis, CA 95616 (United States)

2013-10-10

318

Interfacial water. The structure of interfacial water on gold electrodes studied by x-ray absorption spectroscopy.  

PubMed

The molecular structure of the electrical double layer determines the chemistry in all electrochemical processes. Using x-ray absorption spectroscopy (XAS), we probed the structure of water near gold electrodes and its bias dependence. Electron yield XAS detected at the gold electrode revealed that the interfacial water molecules have a different structure from those in the bulk. First principles calculations revealed that ~50% of the molecules lie flat on the surface with saturated hydrogen bonds and another substantial fraction with broken hydrogen bonds that do not contribute to the XAS spectrum because their core-excited states are delocalized by coupling with the gold substrate. At negative bias, the population of flat-lying molecules with broken hydrogen bonds increases, producing a spectrum similar to that of bulk water. PMID:25342657

Velasco-Velez, Juan-Jesus; Wu, Cheng Hao; Pascal, Tod A; Wan, Liwen F; Guo, Jinghua; Prendergast, David; Salmeron, Miquel

2014-11-14

319

Preliminary Testing of a Water-Vapor Differential Absorption LIDAR (DIAL) Using a Widely Tunable Amplified Diode Laser Source  

Microsoft Academic Search

Water vapor plays an enormous role in Earth's atmospheric dynamics through cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Detailed data of water vapor distribution and flux and related feedback mechanisms are required to better understand and predict local weather, global climate, and the water cycle. One method of obtaining this data in

Michael D. Obland; Kevin S. Repasky; Joseph A. Shaw; John L. Carlsten

2006-01-01

320

QSPR models of boiling point, octanol- water partition coefficient and retention time index of polycyclic aromatic hydrocarbons  

Microsoft Academic Search

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 ðlog KowÞ 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

Fabiana Alves de Lima; Marcia Miguel Castro Ferreira

321

QSPR models of boiling point, octanol–water partition coefficient and retention time index of polycyclic aromatic hydrocarbons  

Microsoft Academic Search

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,

Fabiana Alves de Lima Ribeiro; Márcia Miguel Castro Ferreira

2003-01-01

322

Investigation of the Influence of Cooling Water Inlet Temperature on Characteristics and Ammonia Charging Quantity of Ammonia-Water Absorption Refrigerator  

NASA Astrophysics Data System (ADS)

For purposes such as freezing and ice accumulation which require temperatures below 0 degrees, ammonia-water absorption refrigerator is being looked at once again. If used for these purpose, it is usually driven all through the year. In this case, cooling water inlet temperature which greatly influences absorption cycle changes very widely. So in such conditions, it is hoped to be driven high efficiently. And ammonia's charging quantity is required as small as possible on account of poisonous. But when it driven all through the year, ammonia charging quantity influences the efficiency greatly. So this research aims to clarify the ammonia charging quantity with which ammonia-water absorption refrigerator can be driven high efficiently. So static simulation model was made. By using this tool, we investigated the influence of cooling water inlet temperature on COP, solution concentration. As a result, minimum ammonia charging quantity with which ammonia water absorption refrigerator can be driven was obtained.

Takei, Toshitaka; Saito, Kiyoshi; Kawai, Sunao

323

Kenaf/recycled Jute Natural Fibers Unsaturated Polyester Composites: Water Absorption/dimensional Stability and Mechanical Properties  

NASA Astrophysics Data System (ADS)

Effects of water absorption on the flexural properties of kenaf-unsaturated polyester composites and kenaf/recycled jute-unsaturated polyester composites were investigated. In the hybrid composites, the total fiber content was fixed to 20 wt%. In this 20 wt%, the addition of jute fiber varied from 0 to 75%, with increment of 25%. The result demonstrates the water absorption and the thickness swelling increased with increase in immersion time. Effects of water absorption on flexural properties of kenaf fiber composites can be reduced significantly with incorporation of recycled jute in composites formulation. The process of absorption of water was found to approach Fickian diffusion behavior for both kenaf composites and hybrid composites.

Osman, Ekhlas A.; Vakhguelt, Anatoli; Sbarski, Igor; Mutasher, Saad A.

2012-03-01

324

Determination of the diffusion coefficient between corn syrup and distilled water using a digital camera  

NASA Astrophysics Data System (ADS)

A simple technique for determining the diffusion coefficient between two miscible liquids is presented based on observing concentration-dependent ultraviolet-excited fluorescence using a digital camera. The ultraviolet-excited visible fluorescence of corn syrup is proportional to the concentration of the syrup. The variation of fluorescence with distance from the transition zone between the fluids is fit by the Fick's law solution to the diffusion equation. By monitoring the concentration at successive times, the diffusion coefficient can be determined in otherwise transparent materials. The technique is quantitative and makes measurement of diffusion accessible in the advanced undergraduate physics laboratory.

Ray, E.; Bunton, P.; Pojman, J. A.

2007-10-01

325

Differential absorption and Raman lidar for water vapor profile measurements; A review  

SciTech Connect

Differential absorption lidar and Raman lidar have been applied to the range-resolved measurements of water vapor density for more than 20 years. During this period, there have been considerable advances in laser and lidar technology, as well as in the understanding of the factors required to optimize both lidar techniques for water vapor measurements. Results have been obtained using both lidar techniques that have led to improved understanding of water vapor distributions in the atmosphere. This paper reviews the theory of the measurements, including the sources of systematic and random error; the progress in lidar technology and techniques during that period, including a brief look at some of the lidar systems in development or proposed; and the steps being taken to improve such lidar systems.

Grant, W.B. (NASA/Langley Research Center, Atmospheric Sciences Div., MS 401A, Hampton, VA (US))

1991-01-01

326

Performance of Generator of Absorption Refrigerating Machine Powered by Hot Water  

NASA Astrophysics Data System (ADS)

For 70 kW generator of absorption refrigerating machine powered by the hot water, lifted liquid rate of the bubble lift pump has a maximum value at some vapor flow rate of refrigerant and hot water inlet temperature. This is in agreement with results of small size bubble lift pump. Maximum lifted liquid rate G0 is correlated by the equation G0 = 5, 000?1.5, where ? is the degree of submergence. In this case, diameter of pump tube was 41.6mm, and length of it were 1,300 and 1,500mm. The range of hot water inlet temperature was 78 - 100°C. Multitube heat flux of first generator is about two times that of second generator at the same superheat.

Kunugi, Yoshifumi; Usui, Sanpei; Ouchi, Tomihisa; Fukuda, Tamio

327

A high energy diode-pumped Cr:LiSAF laser for water vapor differential absorption lidar  

Microsoft Academic Search

Summary form only given. The near-IR absorption bands in the 810-830 nm and 930-950 nm range are well suited for remote measurements of water vapor with differential absorption lidar. A diode-pumped Cr:LiSAF laser which can be tuned over these bands has a great potential as a compact and efficient, narrow linewidth source for atmospheric water vapor DIAL. We present the

V. Fromzel; C. R. Prasad; C. Johnson; N. P. Barnes; G. H. Kim; R. D. Mead

1999-01-01

328

A new evaluation of the wind stress coefficient over water surfaces  

Microsoft Academic Search

An analysis of data from numerous investigators, as well as information obtained directly by the authors, indicates that a large portion of the difficulties encountered in the past in establishing a relationship between wind stress coefficient C10 and the wind velocity U10 can be attributed to computationally induced scatter of the data points. However, plots of the shear velocity u*

J. Amorocho; J. J. DeVries

1980-01-01

329

Optimized split-window coefficients for deriving surface temperatures from inland water bodies  

Microsoft Academic Search

Large inland water bodies constituting lakes, reservoirs and inland-seas are excellent proxy indicators for climate change. Using thermal infrared satellite data, a recent study found that a global set of inland water bodies showed significant warming in seasonal nighttime Lake Surface Water Temperatures (LSWTs) between 1985 and 2009. Split-window land surface temperature (LST) retrievals are typically tuned for a broad

Glynn C. Hulley; Simon J. Hook; Philipp Schneider

330

Microclimate in ski boots--temperature, relative humidity, and water absorption.  

PubMed

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

Hofer, Patrick; Hasler, Michael; Fauland, Gulnara; Bechtold, Thomas; Nachbauer, Werner

2014-05-01

331

Probing the vibrational dynamics of proteins in liquid water by terahertz absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Biomolecules solvated in their biologically milieu are expected to exhibit strong absorption in the terahertz range that contain information on their global and subglobal collective vibrational modes and global dynamical correlations among solvent water molecules and the protein. Measurements in this region, however, are challenging due to due to the strong absorption of water and often sever interference artifacts. In response, we have developed, with Virginia Diode Inc., a highly sensitive Vector Network Analyzer system for probing collective dynamics in aqueous solution. Using this we explore the complex dielectric response from 0.07 to 0.70 THz that directly probes such questions as the hydration level around proteins and the large scale vibrational modes of biological polymers. We make a direct comparison to the existing molecular dynamic simulations and normal mode calculations and investigate the dependence of the low frequency dynamics on protein concentration and solvent pH. Our measurements shed light on the macromolecular motions in a biologically relevant water environment.

Quang Vinh, Nguyen; Plaxco, Kevin W.; Allen, S. James

2010-03-01

332

High-resolution atmospheric water vapor measurements with a scanning differential absorption lidar  

NASA Astrophysics Data System (ADS)

The scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) is presented. The UHOH DIAL is equipped with an injection-seeded frequency-stabilized high-power Ti:sapphire laser operated at 818 nm with a repetition rate of 250 Hz. A scanning transceiver unit with a 80 cm primary mirror receives the atmospheric backscatter signals. The system is capable of water vapor measurements with temporal resolutions of a few seconds and a range resolution between 30 and 300 m at daytime. It allows to investigate surface-vegetation-atmosphere exchange processes with high resolution. In this paper, we present the design of the instrument and illustrate its performance with recent water vapor measurements taken in Stuttgart-Hohenheim and in the frame of the HD(CP)2 Observational Prototype Experiment (HOPE). HOPE was located near research center Jülich, in western Germany, in spring 2013 as part of the project "High Definition of Clouds and Precipitation for advancing Climate Prediction" (HD(CP)2). Scanning measurements reveal the 3-dimensional structures of the water vapor field. The influence of uncertainties within the calculation of the absorption cross-section at wavelengths around 818 nm for the WV retrieval is discussed. Radiosonde intercomparisons show a very small bias between the instruments of only (-0.04 ± 0.11) g m-3 or (-1.0 ± 2.3) % in the height range of 0.5 to 3 km.

Späth, F.; Behrendt, A.; Muppa, S. K.; Metzendorf, S.; Riede, A.; Wulfmeyer, V.

2014-11-01

333

Cloud point extraction-flame atomic absorption spectrometry method for preconcentration and determination of trace cadmium in water samples.  

PubMed

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

Ning, Jinyan; Jiao, Yang; Zhao, Jiao; Meng, Lifen; Yang, Yaling

2014-01-01

334

Absorption of crystalline water ice in the far infrared at different temperatures  

NASA Astrophysics Data System (ADS)

The optical properties of ice in the far infrared are important for models of protoplanetary and debris disks. In this report, we derive a new set of data for the absorption (represented by the imaginary part of the refractive index ?) of crystalline water ice in this spectral range. The study includes a detailed inspection of the temperature dependence, which has not been conducted in such detail before. We measured the transmission of three ice layers with different thicknesses at temperatures ? = 10...250 K and present data at wavelengths ? = 80...625 ?m. We found a change in the spectral dependence of ? at a wavelength of 175 ± 6 ?m. At shorter wavelengths, ? exhibits a constant flat slope and no significant temperature dependence. Long-ward of that wavelength, the slope gets steeper and has a clear, approximately linear temperature dependence. This change in behaviour is probably caused by a characteristic absorption band of water ice. The measured data were fitted by a power-law model that analytically describes the absorption behaviour at an arbitrary temperature. This model can readily be applied to any object of interest, for instance a protoplanetary or debris disk. To illustrate how the model works, we simulated the spectral energy distribution (SED) of the resolved, large debris disk around the nearby solar-type star HD 207129. Replacing our ice model by another, commonly used data set for water ice results in a different SED slope at longer wavelengths. This leads to changes in the characteristic model parameters of the disk, such as the inferred particle size distribution, and affects the interpretation of the underlying collisional physics of the disk.

Reinert, C.; Mutschke, H.; Krivov, A. V.; Löhne, T.; Mohr, P.

2015-01-01

335

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

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

336

Salting-in and salting-out effects of ionic and neutral osmotica on limonene and linalool Henry’s law constants and octanol\\/water partition coefficients  

Microsoft Academic Search

Foliar emission rates of plant-generated volatile monoterpenes depend on monoterpene partitioning between air, aqueous and lipid-phases in the leaves. While Henry’s law constants (Hpc, equilibrium gas\\/water partition coefficient) and octanol\\/water partition coefficients (KOW) for pure water have been previously used to simulate monoterpene emissions from the leaves, aqueous phase in plants is a complex solution of electrolytes and neutral osmotica.

Lucian Copolovici; Ülo Niinemets

2007-01-01

337

Transpiration, crop coefficient and water use of Olive tree (cv. Cordovil) in Southern Portugal  

NASA Astrophysics Data System (ADS)

Orchard olive transpiration, soil water status and stomatal response in relation to water deficit were investigated to clarify mechanisms of tree water uptake and stomatal control to improve the irrigation scheduling of low-density olive trees of cv. Cordovil grown in typical Mediterranean environment of Southern Portugal. Trees were subject to three irrigation treatments. Treatment A received 100% of crop evapotranspiration by a drip irrigation system, a sustained deficit (SDI)treatment B received 60% of crop evapotranspiration, a regulated deficit(RDI) irrigation treatment C received irrigation water before-flowering and just before pit-hardening, and a Dry-farming treatment. Tree and orchard transpiration and the dynamics of water uptake by roots were estimated from sap flow measurements and water balance technique. Stomatal conductance was modeled from local meteorological variables, measured sap flow and tree canopy variables. Higher than treatment A and B stomatal conductance and the high tree fruit production recommend treatment C as most suitable for scheduling irrigation of olive orchards in wet years of well distributed late summer rainfall. For drier years of no summer and early autumn rains that minimizes available water to extract by roots outside the wet bulb of drip irrigation and for the scarce readily available irrigation water years, as so often occurs in the region, the sustained deficit irrigation (SDI) regime seems a better option. Nonetheless, for years of limited available water resources that preclude sustained deficit irrigation, careful management of the proposed RDI could also allow for efficient use of irrigation water.

Santos, F. L.

2008-12-01

338

Evidence for direct water absorption by shallow-rooted desert plants in desert-oasis ecotone, Northwest China  

NASA Astrophysics Data System (ADS)

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.

Fang, Jing

2014-05-01

339

Coefficients of caffeine distribution in aliphatic alcohol-ammonium sulfate-water systems  

NASA Astrophysics Data System (ADS)

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.

Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

2012-11-01

340

Experimental Study of Diffusion Coefficients of Water through the Collagen: Apatite Porosity in Human Trabecular Bone Tissue  

PubMed Central

We firstly measured the swelling of single trabeculae from human femur heads during water imbibition. Since the swelling is caused by water diffusing from external surfaces to the core of the sample, by measuring the sample swelling over time, we obtained direct information about the transport of fluids through the intimate constituents of bone, where the mineralization process takes place. We developed an apparatus to measure the free expansion of the tissue during the imbibition. In particular, we measured the swelling along three natural axes (length L, width W, and thickness T) of plate-like trabeculae. For this aim, we developed a 3D analytical model of the water uptake by the sample that was performed according to Fickian transport mechanism. The results were then utilized to predict the swelling over time along the three sample directions (L, W, T) and the apparent diffusion coefficients DT, DW, and DL. PMID:24967405

Bini, Fabiano; Marinozzi, Andrea

2014-01-01

341

X-ray absorption signatures of the molecular environment in water and ice  

E-print Network

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.

Wei Chen; Xifan Wu; Roberto Car

2009-09-21

342

High-resolution spectroscopy of cool K and M stars through the telluric water vapor absorption band near 9360 A. 1: Methodology and first results  

Microsoft Academic Search

An observational program has been undertaken for the study of stellar spectra within telluric water vapor lines absorption region near 9360 A. This program has been developed in the future context of a European Space Agency's (ESAs) environment-dedicated experiment designed to probe atmospheric water vapor absorption with cool star spectrophotometry. With ground observations presented here, we determine absorption levels and

T. Widemann; J.-L. Bertaux; M. Querci; F. Querci

1994-01-01

343

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

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

Xu, Jing

344

Sublimation coefficient of water ice under simulated cometary-like conditions  

NASA Astrophysics Data System (ADS)

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.

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

1999-12-01

345

Progress toward a water-vapor differential absorption lidar (DIAL) using a widely tunable amplified diode laser source  

Microsoft Academic Search

Water vapor is one of the most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water vapor and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the

Michael D. Obland; Lei S. Meng; Kevin S. Repasky; Joseph A. Shaw; John L. Carlsten

2005-01-01

346

Solar cooling with the absorption principle: first and Second Law analysis of an ammonia—water double-generator absorption chiller  

Microsoft Academic Search

This article deals with the modelling, thermodynamic simulation and Second Law analysis of an ammonia—water double-effect, double-generator absorption chiller. The analysis of the unit established a simulation thermodynamic model as well as the limits of the operating conditions. Computer simulation was carried out in order to determine its stream properties and the amount of heat and work exchanged with the

N. Ben Ezzine; M. Barhoumi; Kh. Mejbri; S. Chemkhi; A. Bellagi

2004-01-01

347

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

348

K? absorption by locust gut and inhibition of ileal K? and water transport by FGLamide allatostatins.  

PubMed

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

Robertson, Lisa; Donini, Andrew; Lange, Angela B

2014-09-15

349

Mass absorption efficiency of elemental carbon and water-soluble organic carbon in Beijing, China  

NASA Astrophysics Data System (ADS)

The mass absorption efficiency (MAE) of elemental carbon (EC) in Beijing was quantified using a thermal-optical carbon analyzer. The MAE measured at 632 nm was 8.45±1.71 and 9.41±1.92 m2 g-1 during winter and summer respectively. The daily variation of MAE was found to coincide with the abundance of organic carbon (OC), especially the OC to EC ratio, perhaps due to the enhancement by coating with organic aerosol (especially secondary organic aerosol, SOA) or the artifacts resulting from the redistribution of liquid-like organic particles during the filter-based absorption measurements. Using a converting approach that accounts for the discrepancy caused by measurements methods of both light absorption and EC concentration, previously published MAE values were converted to the equivalent-MAE, which is the estimated value if using the same measurement methods as used in this study. The equivalent-MAE was found to be much lower in the regions heavily impacted by biomass burning (e.g., below 2.7 m2 g-1 for two Indian cities). Results from source samples (including diesel exhaust samples and biomass smoke samples) also demonstrated that emissions from biomass burning would decrease the MAE of EC. Moreover, optical properties of water-soluble organic carbon (WSOC) in Beijing were presented. Light absorption by WSOC exhibited strong wavelength (?) dependence such that absorption varied approximately as ?-7, which was characteristic of the brown carbon spectra. The MAE of WSOC (measured at 365 nm) was 1.79±0.24 and 0.71±0.20 m2 g-1 during winter and summer respectively. The large discrepancy between the MAE of WSOC during winter and summer was attributed to the difference in the precursors of SOA such that anthropogenic volatile organic compounds (AVOCs) should be more important as the precursors of SOA in winter. The MAE of WSOC in Beijing was much higher than results from the southeastern United States which were obtained using the same method as used in this study, perhaps due to the stronger emissions of biomass burning in China.

Cheng, Y.; He, K.-B.; Zheng, M.; Duan, F.-K.; Du, Z.-Y.; Ma, Y.-L.; Tan, J.-H.; Yang, F.-M.; Liu, J.-M.; Zhang, X.-L.; Weber, R. J.; Bergin, M. H.; Russell, A. G.

2011-11-01

350

In vivo and in vitro absorption and binding to powdered stratum corneum as methods to evaluate skin absorption of environmental chemical contaminants from ground and surface water  

Microsoft Academic Search

The objectives of this study were to compare methods to determine the binding and absorption of water contaminants to skin, to examine linearity of response, and to determine whether skin was an environmental route for water contaminants to enter the body. The three chemical examined were (¹⁴C)-p-nitroaniline (10.1 mCi\\/mM), (¹⁴C)benzene (56 mCi\\/mM, and ¹⁴C-labeled 54% PCB (32 mCi\\/mM). The chemical

Ronald C. Wester; Mohammad Mobayen; Howard I. Maibach

1987-01-01

351

Surfactant\\/oil\\/water system for the determination of selenium in eggs by graphite furnace atomic absorption spectrometry  

Microsoft Academic Search

An oil-in-water formulation has been optimized to determine trace levels of selenium in whole hen eggs by graphite furnace atomic absorption spectrometry. This method is simpler and requires fewer reagents when compared with other sample pre-treatment procedures. Graphite furnace atomic absorption spectrometric (GF AAS) measurement was carried out using standard addition calibration and Pd as a modifier. The precision, expressed

C. V. S. Ieggli; D. Bohrer; S. Noremberg; P. C. do Nascimento; L. M. de Carvalho; S. L. Vieira; R. N. Reis

2009-01-01

352

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...

353

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

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

354

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...

355

A study of the water vapor absorption for integrating humidity sensor  

NASA Astrophysics Data System (ADS)

Humidity can damage components of electronic systems, such as missiles, so such systems must be stored in containers, which are impermeable to moisture. Conventional humidity sensors measure the current humidity level and thus can not detect if a transient high humidity level had occurred prior to the measurement. However, the output of an integrating humidity sensor reflects a past high humidity level, even if the current humidity level is low, and can be used to indicate if damage may have occurred during storage or transport. In this study, an integrating humidity sensor consisting of hygroscopic salt particles (magnesium sulfate) dispersed in a polybutadiene polymer film has been fabricated and investigated. Upon exposure to moisture, the water vapor reacts with the hygroscopic salt and results in a change of the electrical properties of the film. The change in capacitance is related to the amount of water vapor absorbed by the hybrid polymer film. Even after the humidity level is reduced, the sensor output is still different from the initial value. This reaction is irreversible so the sensor response is related to the total amount of water vapor during exposure. Electrochemical impedance spectroscopy is used to study the mechanism of water vapor absorption during sensor exposure to the humidity environment. The experimental data analyzed with complex plots and Bode plots indicate that the integrating humidity sensor exhibits a change from capacitive behavior to resistive behavior after exposure to humidity environment for 35 days later. Analysis of these impedance plots indicates that both electron charge transfer processes and diffusion processes occurred during the sensor exposure. Based on this physical understanding, the proposed equivalent circuit model was constructed using a ladder network with a transmission line model, which is called a Warburg impedance, and employed in a computer simulation to analyze the electrochemical impedance behavior of the integrating humidity sensor. The computer simulation results indicate that mass transfer diffusion processes dominate the water vapor absorption mechanism in the early exposure. However, electron charge transfer processes prevail over the diffusion process after the hygroscopic salts are saturated.

Hsu, Tingkuei

356

Comparison of x-ray absorption spectra between water and ice: new ice data with low pre-edge absorption cross-section.  

PubMed

The effect of crystal growth conditions on the O K-edge x-ray absorption spectra of ice is investigated through detailed analysis of the spectral features. The amount of ice defects is found to be minimized on hydrophobic surfaces, such as BaF2(111), with low concentration of nucleation centers. This is manifested through a reduction of the absorption cross-section at 535 eV, which is associated with distorted hydrogen bonds. Furthermore, a connection is made between the observed increase in spectral intensity between 544 and 548 eV and high-symmetry points in the electronic band structure, suggesting a more extended hydrogen-bond network as compared to ices prepared differently. The spectral differences for various ice preparations are compared to the temperature dependence of spectra of liquid water upon supercooling. A double-peak feature in the absorption cross-section between 540 and 543 eV is identified as a characteristic of the crystalline phase. The connection to the interpretation of the liquid phase O K-edge x-ray absorption spectrum is extensively discussed. PMID:25053326

Sellberg, Jonas A; Kaya, Sarp; Segtnan, Vegard H; Chen, Chen; Tyliszczak, Tolek; Ogasawara, Hirohito; Nordlund, Dennis; Pettersson, Lars G M; Nilsson, Anders

2014-07-21

357

Influence of drug physicochemical properties on absorption of water insoluble drug nanosuspensions.  

PubMed

In order to investigate the influence of drug physicochemical properties on bioavailability of water insoluble drug nanosuspensions, five drug nanosuspensions were prepared using high pressure homogenization. These nanosuspensions were similar in particle size and same in stabilizer. Differential scanning calorimetry and powder X-ray diffraction analysis showed the crystalline state of the freeze dried nanocrystals did not change. In vitro dissolution test in fasted state simulated intestinal fluid (FaSSIF) and in vivo bioavailability study in rats demonstrated that the nanosuspensions had higher dissolution rate and higher AUC0-t and the ratios of dissolvednano/dissolvedmicro in 120 min were well correlated with the ratios of AUC0-t nano/AUC0-t micro. Correlation analysis between drug physicochemical properties and AUC0-t nano was performed and four-grid interpolation method was employed for interpolation and smooth surface fitting to give a visible trend. The results revealed that drug with smaller melting point, logP value around 5 and polar surface area value in the range of 50-60 would gain higher AUC0-t nano and accordingly better absorption of its nanosuspension. Melting point, logP and polar surface area were factors that influence the absorption of drug nanosuspensions in this study. PMID:24184036

Li, Wei; Quan, Peng; Zhang, Yaqiong; Cheng, Jing; Liu, Jie; Cun, Dongmei; Xiang, Rongwu; Fang, Liang

2014-01-01

358

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

PubMed

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. PMID:21694286

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

2008-05-21

359

Evaluation of tropospheric water vapor profiling using eye-safe, infrared differential absorption lidar  

SciTech Connect

Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution are fundamental to the success of the ARM CART program. In addition, these should be acquired over long periods at low operational and maintenance cost. The development and verification of realistic climate model parameterizations for clouds and net radiation balance, and the correction of other CART site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. To date, application of profiles have been limited by vertical resolution and uniqueness and high operating cost, or diminished daytime performance, lack of eye-safety, and high maintenance cost. Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the studies reported here, we develop DIAL system performance models and examine the potential of solving some of the shortcomings of previous methods using parameters representative of current technologies. These simulations are also applied to determine the strengths and weaknesses unique to the DIAL method for this application.

Rye, B.J. [Colorado Univ., Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences]|[National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.; Machol, J.L.; Grund, C.J.; Hardesty, R.M. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.

1996-05-14

360

A Water Vapor Differential Absorption LIDAR Design for Unpiloted Aerial Vehicles  

NASA Technical Reports Server (NTRS)

This system study proposes the deployment of a water vapor Differential Absorption LIDAR (DIAL) system on an Altair unmanned aerial vehicle (UAV) platform. The Altair offers improved payload weight and volume performance, and longer total flight time as compared to other commercial UAV's. This study has generated a preliminary design for an Altair based water vapor DIAL system. The design includes a proposed DIAL schematic, a review of mechanical challenges such as temperature and humidity stresses on UAV deployed DIAL systems, an assessment of the available capacity for additional instrumentation (based on the proposed design), and an overview of possible weight and volume improvements associated with the use of customized electronic and computer hardware, and through the integration of advanced fiber-optic and laser products. The results of the study show that less than 17% of the available weight, less than 19% of the volume capacity, and approximately 11% of the electrical capacity is utilized by the proposed water vapor DIAL system on the Altair UAV.

DeYoung, Russell J.; Mead, Patricia F.

2004-01-01

361

Ground-based differential absorption lidar for water-vapor and temperature profiling: methodology.  

PubMed

A comprehensive formulation of the differential absorption lidar (DIAL) methodology is presented that explicitly includes details of the spectral distributions of both the transmitted and the backscattered light. The method is important for high-accuracy water-vapor retrievals and in particular for temperature measurements. Probability estimates of the error that is due to Doppler-broadened Rayleigh scattering based on an extended experimental data set are presented, as is an analytical treatment of errors that are due to averaging in the nonlinear retrieval scheme. System performance requirements are derived that show that water-vapor retrievals with an accuracy of better than 5% and temperature retrievals with an accuracy of better than 1 K in the entire troposphere are feasible if the error that results from Rayleigh-Doppler correction can be avoided. A modification of the DIAL technique, high-spectral-resolution DIAL avoids errors that are due to Doppler-broadened Rayleigh backscatter and permits simultaneous water-vapor and wind measurements with the same system. PMID:18273353

Bösenberg, J

1998-06-20

362

Water absorption of poly(methyl methacrylate) measured by vertical interference microscopy.  

PubMed

PMMA (poly(methyl methacrylate)) is widely used to prepare orthopedic cements. They are in direct contact with cells and body fluids. PMMA, despite its hydrophobic nature, can absorb ~2% w/w water. We have evaluated by vertical interference microscopy if water absorption can produce a significant swelling in different types of PMMA blocks: pure, with a plasticizer, with a cross-linker, and in two types of commercial bone cements. Graphite rods which do not swell in water were used as internal standard. Hardness, indentation modulus, plastic, and elastic works were determined by nanoindentation under a 25mN fixed force. Vertical interference microscopy was used to image the polymer in the dry state and hydrated states (after 24 h in distilled water). On the surface of the polished polymers (before and after hydration), we measured roughness by the fractal dimension, the swelling in the vertical and the lateral directions. For each polymer block, four images were obtained and values were averaged. Comparison and standardization of the images in the dry and hydrated states were done with Matlab software. The average value measured on the graphite rod between the two images (dried and hydrated) was used for standardization of the images which were visualized in 3D. After grinding, a small retraction was noticeable between the surface of the rod and the polymers. A retraction ring was also visible around the graphite rod. After hydration, only the pure PMMA and bone cements had a significant swelling in the vertical direction. The presence of polymer beads in the cements limited the swelling in the lateral direction. Swelling parameters correlated with the nanoindentation data. PMMA can swell by absorbing a small amount of water and this induces a swelling that varies with the polymer composition and particle inclusions. PMID:22799564

N'Diaye, Mambaye; Pascaretti-Grizon, Florence; Massin, Philippe; Baslé, Michel Felix; Chappard, Daniel

2012-08-01

363

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

NASA Technical Reports Server (NTRS)

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.

Kenimer, R. L.

1988-01-01

364

Determination of barium in bottled drinking water by graphite furnace atomic absorption spectrometry  

SciTech Connect

In relation to the wide environmental spread of barium and to its cardiovascular effects, barium levels were determined by graphite furnace atomic absorption spectrometry in 60 different brands of bottled water marketed in Italy. Matrix interferences were investigated in order to evaluate the use of an analytical calibration function rather than the much more time consuming addition technique. The barium content ranged from limit of detection C/sub L/ (7.0 ..mu..g/1) up to 660 ..mu..g/1, the median value being 80 ..mu..g/l, while the recovery tests varied between 90 and 110% and the precision of the method (s/sub yx/) was 2.5%.

Fagioli, F.; Locatelli, C.; Lanciotti, E.; Vallone, G.; Mazzotta, D.; Mugelli, A.

1988-11-01

365

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

SciTech Connect

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.

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

366

Calculation of diffusion coefficients of water and alkanes through single-walled carbon nanotubes from simulations  

SciTech Connect

Recent experimental work has shown that membranes containing aligned carbon nanotubes exhibit transport rates for gases and liquids that are orders of magnitude larger than rates predicted from Knudsen or hydrodynamic no-slip flow. We present atomically detailed simulations of diffusion of water and alkanes through single-walled carbon nanotubes. The self, corrected, and transported diffusivities are calculated for liquid-like densities of water and alkanes in nanotubes using equilibrium molecular dynamics, with thermodynamic correction factors computed from Monte Carlo adsorption isotherm calculations. We also present the zero-coverage diffusivities for these fluids. We discuss the results in comparison with bulk fluid self-diffusivities and experimental data for flow through nanotubes membranes.

Johnson, J.K.; Wang, Y.; Liu, J.-C.; Sholl, D.S.

2007-08-01

367

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

NASA Astrophysics Data System (ADS)

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

Bunk, Rüdiger; Quan, Zhi; Wandel, Matthias; Yi, Zhigang; Bozem, Heiko; Kesselmeier, Jürgen

2014-05-01

368

Estimation of distribution coefficient of natural radionuclides in soil around uranium mines and its effect with ionic strength of water.  

PubMed

The distribution coefficient, K(d) in soil is an important parameter to predict the migration of contaminants. In this study, uranium (U) and its decay products thorium (Th), radium (Ra), bismuth (Bi), lead (Pb) and polonium (Po), which may contaminate the soil and ground water around uranium mining areas, have been considered. Soil and ground water samples were collected from a proposed uranium mining site in India. The soil samples were characterised for different parameters affecting the K(d) values. The batch sorption method was employed to measure the K(d) of different radionuclides. The important factors affecting the batch method for K(d) estimation were identified and optimised. The variation of K(d) was observed with different ionic strength water samples. Results showed high K(d) values for Th(IV), Po(IV) and Pb(II) (log K(d) ?4) and low K(d) (log K(d) ?2-3) for U(VI), Ra(II) and Bi(III) in all three types of water with different ionic strength. PMID:22927651

Mishra, S; Maity, S; Pandit, G G

2012-11-01

369

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

E-print Network

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...

Karimian, Najafali

1970-01-01

370

A linear relationship between the Hall carrier concentration and the effective absorption coefficient measured by means of photothermal radiometry in IR semi-transparent n-type CdMgSe mixed crystals  

NASA Astrophysics Data System (ADS)

In this work we demonstrate the ability to measure the effective infrared absorption coefficient in semiconductors by a photothermal infrared radiometry (PTR) experiment, and its correlation with the Hall carrier concentration. The amplitude and phase of the PTR signal were measured for Cd1-xMgxSe mixed crystals, with the magnesium content varying from x = 0 to x = 0.15. The PTR experiments were performed at room temperature in thermal reflection and transmission configurations using a mercury cadmium telluride infrared detector. The PTR data were analyzed in the frame of the one-dimensional heat transport model for infrared semi-transparent crystals. Based on the variation of the normalized PTR phase and amplitude on the modulation frequency, the thermal diffusivity and the effective infrared absorption coefficient were obtained by fitting the theoretical expression to experimental data and compared with the Hall carrier concentration determined by supplementary Hall experiments. A linear relationship between the effective infrared absorption coefficient and the Hall carrier concentration was found which is explained in the frame of the Drude theory. The uncertainty of the measured slope was 6%. The value of the slope depends on (1) the sample IR absorption spectrum and (2) the spectral range of the infrared detector. It has to be pointed out that this method is suitable for use in an industrial environment for a fast and contactless carrier concentration measurement. This method can be used for the characterization of other semiconductors after a calibration procedure is carried out. In addition, the PTR technique yields information on the thermal properties in the same experiment.

Pawlak, M.; Mali?ski, M.; Firszt, F.; Pelzl, J.; Ludwig, A.; Marasek, A.

2014-03-01

371

Hemodialysis increases apparent diffusion coefficient of brain water in nephrectomized rats measured by isotropic diffusion-weighted magnetic resonance imaging.  

PubMed Central

The nature of brain edema in dialysis disequilibrium syndrome (DDS) was investigated by diffusion-weighted magnetic resonance imaging (DWI). DWI was performed on normal or bilaterally nephrectomized rats before, and immediately after, hemodialysis. Hemodialysis was performed with a custom-made dialyzer (surface area 150 cm2) against a bicarbonate-buffered bath for 90 min with or without 70 mM urea. Hemodialysis with non-urea bath decreased plasma urea by 21 mM, and plasma osmolality by 22 mosmol/kg H2O, and increased brain water content by 8.0% (all < 0.05), while hemodialysis with urea bath did not affect plasma urea, osmolality, or brain water content. Three sets of axial DWI images of the brain were obtained at different gradient weighing factors with an in-plane resolution of 0.39 mm2. The apparent diffusion coefficient (Dapp) of the brain water was not affected by bilateral nephrectomy, or by hemodialysis in normal rats. In nephrectomized rats, brain Dapp was significantly increased after dialysis with non-urea bath (1.15 +/- 0.08 vs 0.89 +/- 0.07 x 10(-9)m2/sec, P < 0.01). No significant changes of brain water Dapp could be observed after dialysis with urea bath. The increased Dapp associated with DDS indicates that brain extracellular water increases and/or intracellular water decreases after hemodialysis. Our results strongly suggest that the brain edema induced by hemodialysis in uremic rats is due to interstitial edema rather than cytotoxic edema. Furthermore, our results support a primary role for the "reverse urea effect" in the pathogenesis of brain edema in DDS.DWI may be a useful diagnostic tool for DDS in patients with end-stage renal disease. PMID:8698867

Galons, J P; Trouard, T; Gmitro, A F; Lien, Y H

1996-01-01

372

In air synthesis of Psy-cl-poly(AAm) network and its application in water-absorption from oil-water emulsions  

Microsoft Academic Search

In this current investigation psyllium has been functionalized with acrylamide in the presence of potassium per- sulphate (KPS)-hexamethylene tetramine (HMTA) as an initiator-crosslinker system. After the initial optimization of dif- ferent reaction parameters the resultant hydrogel was used for the absorption of water from different water-oil emulsions as a function of time, temperature, pH and NaCl concentration. 4216% of water

B. S. Kaith; K. Kumar

2007-01-01

373

Prediction of urban water demand on the basis of Engel's coefficient and Hoffmann index: case studies in Beijing and Jinan, China.  

PubMed

Domestic and industrial water uses are the most important segment of urban water consumption. Traditional urban water demand models are usually based on water consumption quotas or statistical relationships, which usually overestimate urban water demands. The efficiency of domestic and industrial water uses is associated with living standards and levels of industrialization. The correlation coefficient between per capita water consumption and Engel's Coefficient in Beijing and Jinan is 0.62 and 0.53, respectively. These values are much smaller than the correlation between added industrial value and the Hoffmann Index in Beijing (0.95) and Jinan (0.90). Demand models for urban water consumption, including a domestic water demand model based on Engel's Coefficient and an industrial water demand model based on the Hoffmann Index, were developed in this study to predict urban water demand in Beijing and Jinan for 2020. The results show that the models can effectively capture the trends of urban water demand. Urban water consumption in these two cities from 1995 to 2007 was used to calibrate the models. The coefficients of determination for residential and industrial water uses were 0.93 and 0.68 in Beijing, and 0.79 and 0.64 in Jinan. Social, economic and climate scenarios for Beijing and Jinan in 2020 were generated according to the Urban Master Plans for these two cities, and they formed the basis for predictions of water consumption in 2020. The results show that total water consumption will increase by 67.6% in Jinan and 33.0% in Beijing when compared with consumption from 2007. PMID:20651447

Zhi-Guo, Zhang; Yi-sheng, Shao; Zong-xue, Xu

2010-01-01

374

Increased intestinal absorption of insulin in a micellar solution: water-in-oil-in-water insulin micelles.  

PubMed

Water-in-oil-in-water (W/O/W) insulin micelles were prepared, and the possibility of insulin absorption in a micellar form was examined. In this preparation, insulin was trapped in oil droplets of oleic acid in glyceryl-alpha-monooleate. (1) W/O/W insulin micelles were absorbed from the ligated jejunal loop of rabbits to the order of 12.3 to 58.5% of the dose given (10 mU/kg body weight) during the 3-h experimental period. (2) Alloxan diabetic rats were treated with intrajejunal administration of W/O/W insulin micelles at a dosage of either 25 or 50 mU/100 g body weight, three times daily for as long as 14 days. During treatment, a significant reduction in the daily excretion of urinary glucose was observed, concomitant with a decrease in fasting blood glucose. Quantitative estimates suggested that the effectiveness of 25 mU/100 g of intrajejunal W/O/W insulin micelles was comparable to that of regular insulin at a dosage of 1 mU/100 g i.m. These results would indicate that W/O/W insulin micelles, when given enterally, are more effective in lowering blood and urinary glucose levels than W/O/W insulin emulsions in which insulin was trapped in oil droplets of triglyceride. PMID:707000

Shichiri, M; Kawamori, R; Goriya, Y; Kikuchi, M; Yamasaki, Y; Shigeta, Y; Abe, H

1978-01-01

375

Enhancement of the grafting performance and of the water absorption of cassava starch graft copolymer by gamma radiation  

NASA Astrophysics Data System (ADS)

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.

Kiatkamjornwong, Suda; Meechai, Nispa

1997-06-01

376

A theoretical investigation of gaseous absorption by water droplets from SO2-HNO3-NH3-CO2-HCl mixtures  

NASA Technical Reports Server (NTRS)

A physical-chemical model is developed and used to investigate gaseous absorption by water droplets from trace gas mixtures. The model is an extension of that of Carmichael and Peters (1979) and includes the simultaneous absorption of SO2, NH3, HNO3, CO2, and HCl. Gas phase depletion is also considered. Presented results demonstrate that the absorption behavior of raindrops is strongly dependent on drop size, fall distance, trace gas concentrations, and the chemical and physical properties of the constituents of the mixture. In addition, when gas phase depletion is considered, the absorption rates and equilibrium values are also dependent on the precipitation rate itself. Also, the trace constituents liquid phase concentrations may be a factor of six or more lower when gas depletion is considered then when the depletion is ignored. However, the hydrogen ion concentration may be insensitive to the gas phase depletion.

Adewuyi, Y. G.; Carmichael, G. R.

1982-01-01

377

Effect of a Disintegration Mechanism on Wetting, Water Absorption, and Disintegration Time of Orodispersible Tablets  

PubMed Central

The aim of this study was to evaluate the influence of disintegration mechanism of various types of disintegrants on the absorption ratio (AR), wetting time (WT), and disintegration time (DT) of orodispersible tablets (ODTs). ODTs were prepared by direct compression using mannitol as filler and disintegrants selected from a range of swellable, osmotic, and porous disintegrants. Tablets formed were characterized for their water AR, WT, and DT. The porosity and mechanical strength of the tablets were also measured. Results show that the DT of formulated ODTs was directly related to the WT and was a function of the disintegration mechanism of the disintegrant used. The lowest WT and DT were observed for tablets formulated using the osmotic disintegrant sodium citrate and these tablets also showed the lowest AR and porosity. The wetting and disintegration of tablets containing the highly swellable disintegrant, sodium starch glycollate, was slowest despite their high water AR and high tablet porosity. Rapid wetting and disintegration of ODTs were therefore not necessarily related to the porosity of the tablets. PMID:23112534

Pabari, RM; Ramtoola, Z

2012-01-01

378

Light tracking through ice and water—Scattering and absorption in heterogeneous media with PHOTONICS  

NASA Astrophysics Data System (ADS)

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.

Lundberg, J.; Mio?inovi?, P.; Woschnagg, K.; Burgess, T.; Adams, J.; Hundertmark, S.; Desiati, P.; Niessen, P.

2007-11-01

379

Aqueous solubilities, vapor pressures, and 1-octanol-water partition coefficients for C9-C14 linear alkylbenzenes  

USGS Publications Warehouse

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.

Sherblom, P.M.; Gschwend, P.M.; Eganhouse, R.P.

1992-01-01

380

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

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

Lars O. Renberg; S. Göran Sundström

1985-01-01

381

Atmospheric Pre-Corrected Differential Absorption Techniques to Retrieve Columnar Water Vapor: Application to AVIRIS 91/95 Data  

NASA Technical Reports Server (NTRS)

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 nm resolution. This data includes the 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 ratioing 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, the spectral transmittance and radiance are calculated by MODTRAN3 simulations with the new DISORT option. The objective of this work is to test the best performing differential absorption techniques for imaging spectrometry of tropospheric water vapor.

Schlaepfer, Daniel; Borel, Christoph C.; Keller, Johannes; Itten, Klaus I.

1996-01-01

382

Diode-pumped tunable narrow-linewidth Cr:LiSAF lasers for water vapor differential absorption lidars  

Microsoft Academic Search

Diode-pumped, tunable Cr:LiSAF lasers are well suited for airborne water vapor differential absorption lidar application. Three types of diode-pumped, tunable, narrow- linewidth, injection seeded, Q-switched Cr:LiSAF lasers for high resolution atmosheric water vapor DIAL measurements in the wavelength range of 810-830 nm have been developed and investigated. By using a total internal reflection laser resonator configuration, efficient coupling of pump

Victor A. Fromzel; Valery V. Ter-Mikirtychev; Joseph S. Smucz; Coorg R. Prasad; Christyl C. Johnson; Norman P. Barnes; James C. Barnes; Russell DeYoung

2001-01-01

383

Future Performance of Ground-Based and Airborne Water-Vapor Differential Absorption Lidar. I. Overview and Theory  

Microsoft Academic Search

The performance of a future advanced water-vapor differential absorption lidar (DIAL) system is discussed. It is shown that the system has to be a direct-detection system operating in the band of water vapor in the 940-nm wavelength region. The most important features of the DIAL technique are introduced: its clear-air measurement capability, its flexibility, and its simultaneous high resolution and

Volker Wulfmeyer; Craig Walther

2001-01-01

384

Sources and light absorption of water-soluble organic carbon aerosols in the outflow from northern China  

NASA Astrophysics Data System (ADS)

High loadings of anthropogenic carbonaceous aerosols in Chinese air influence the air quality for over one billion people and impact the regional climate. A large fraction (17-80%) of this aerosol carbon is water-soluble, promoting cloud formation and thus climate cooling. Recent findings, however, suggest that water-soluble carbonaceous aerosols also absorb sunlight, bringing additional direct and indirect climate warming effects, yet the extent and nature of light absorption by this water-soluble "brown carbon" and its relation to sources is poorly understood. Here, we combine source estimates constrained by dual carbon isotopes with light-absorption measurements of water-soluble organic carbon (WSOC) for a March 2011 campaign at the Korea Climate Observatory at Gosan (KCOG), a receptor station in SE Yellow Sea for the outflow from northern China. The mass absorption cross section at 365 nm (MAC365) of WSOC for air masses from N. China were in general higher (0.8-1.1 m2 g-1), than from other source regions (0.3-0.8 m2 g-1). However, this effect corresponds to only 2-10% of the radiative forcing caused by light absorption by elemental carbon. Radiocarbon constraints show that the WSOC in Chinese outflow had significantly higher fraction fossil sources (30-50%) compared to previous findings in S. Asia, N. America and Europe. Stable carbon (?13C) measurements were consistent with aging during long-range air mass transport for this large fraction of carbonaceous aerosols.

Kirillova, E. N.; Andersson, A.; Han, J.; Lee, M.; Gustafsson, Ö.

2014-02-01

385

The role of skin absorption as a route of exposure for volatile organic compounds (VOCs) in drinking water  

Microsoft Academic Search

Assessments of drinking water safety rely on the assumption that ingestion represents the principal route of exposure. A review of the experimental literature revealed that skin penetration rates for solvents are remarkably high, and that the stratum corneum is a less effective barrier to penetration than traditionally assumed. Based on published skin absorption rates, we used Fick's law (Jos .

H. S. Brown; D. R. Bishop; C. A. Rowan

1984-01-01

386

Solar aqua-ammonia absorption refrigerator simulation  

Microsoft Academic Search

Thermodynamic analysis of an Ammonia-water absorption refrigeration cycle performance, using solar energy in the generator, is simulated by means of a PC program. The economic feasibility of the system for ice production is studied in two southern locations of Spain. For the solar energy collection unit, a Compound Parabolic Collector (CPC) is considered. The optimal value of the Coefficient of

E. Elegido; J. M. De Juana; M. A. Herrero

1991-01-01

387

Diffusion coefficients of several aqueous alkanolamine solutions  

SciTech Connect

In absorption processes of acid gases (H[sub 2]S, CO[sub 2], COS) in alkanolamine solutions, diffusion coefficients are used for the calculation of the mass transfer rate. The Taylor dispersion technique was applied for the determination of diffusion coefficients of various systems. Experiments with the system KCl in water showed that the experimental setup provides accurate data. For the alkanolamines monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and di-2-propanolamine (DIPA), correlations for the diffusion coefficient as a function of temperature at different concentrations are given. A single relation for every amine has been derived which correlates the diffusion coefficients as a function of temperature and concentration. The temperature was varied between 298 and 348 K, and the concentration between 0 and 4000-5000 mol/m[sup 3]. Furthermore, a modified Stokes-Einstein relation is presented for the prediction of the diffusion coefficients in the alkanolamines in relation to the viscosity of the solvent and the diffusion coefficient at infinite dilution. The diffusion coefficients at low concentrations are compared with some available relations for the estimation of diffusion coefficients at infinite dilution, and it appears that the agreement is fairly good.

Snijder, E.D.; Riele, M.J.M. te; Versteeg, G.F.; Swaaij, W.P.M. van (Twente Univ. of Technology, Enschede (Netherlands). Dept. of Chemical Engineering)

1993-07-01

388

Determination of diffusion coefficients of carbon dioxide in water between 268 and 473 K in a high-pressure capillary optical cell with in situ Raman spectroscopic measurements  

USGS Publications Warehouse

Accurate values of diffusion coefficients for carbon dioxide in water and brine at reservoir conditions are essential to our understanding of transport behavior of carbon dioxide in subsurface pore space. However, the experimental data are limited to conditions at low temperatures and pressures. In this study, diffusive transfer of carbon dioxide in water at pressures up to 45 MPa and temperatures from 268 to 473 K was observed within an optical capillary cell via time-dependent Raman spectroscopy. Diffusion coefficients were estimated by the least-squares method for the measured variations in carbon dioxide concentration in the cell at various sample positions and time. At the constant pressure of 20 MPa, the measured diffusion coefficients of carbon dioxide in water increase with increasing temperature from 268 to 473 K. The relationship between diffusion coefficient of carbon dioxide in water [D(CO2) in m2/s] and temperature (T in K) was derived with Speedy–Angell power-law approach as: D(CO2)=D0[T/Ts-1]m where D0 = 13.942 × 10?9 m2/s, Ts = 227.0 K, and m = 1.7094. At constant temperature, diffusion coefficients of carbon dioxide in water decrease with pressure increase. However, this pressure effect is rather small (within a few percent).

Lu, Wanjun; Guo, Huirong; Chou, I.-M.; Burruss, R.C.; Li, Lanlan

2013-01-01

389

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)

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.

Tang, Yongxin; Yang, Shaoyue L.; Lehmann, Kevin K.; Benner, D. Chris

2011-06-01

390

Carrier Mediated Distribution System (CAMDIS): A new approach for the measurement of octanol/water distribution coefficients.  

PubMed

Here we present a miniaturized assay, referred to as Carrier-Mediated Distribution System (CAMDIS) for fast and reliable measurement of octanol/water distribution coefficients, logDoct. By introducing a filter support for octanol, phase separation from water is facilitated and the tendency of emulsion formation (emulsification) at the interface is reduced. A guideline for the best practice of CAMDIS is given, describing a strategy to manage drug adsorption at the filter-supported octanol/buffer interface. We validated the assay on a set of 52 structurally diverse drugs with known shake flask logDoct values. Excellent agreement with literature data (r(2)=0.996, standard error of estimate, SEE=0.111), high reproducibility (standard deviation, SD<0.1 logDoct units), minimal sample consumption (10?L of 100?M DMSO stock solution) and a broad analytical range (logDoct range=-0.5 to 4.2) make CAMDIS a valuable tool for the high-throughput assessment of logDoct. PMID:25513709

Wagner, Bjoern; Fischer, Holger; Kansy, Manfred; Seelig, Anna; Assmus, Frauke

2015-02-20

391

Effect of morphology and solvent on two-photon absorption of nano zinc oxide  

SciTech Connect

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.

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

392

Selective absorption of water from different oil-water emulsions with Psy-cl-poly(AAm) synthesized using irradiation copolymerization method  

Microsoft Academic Search

The present paper deals with the functionalization of psyllium with acrylamide under the influence of gamma radiation using\\u000a hexamethylene tetramine as a crosslinker. The polymer synthesized was characterized using FTIR spectroscopy, scanning electron\\u000a microscopy and thermogravimetric analysis. The superabsorbent was then used further for the selective absorption of water\\u000a from different oil-water emulsions.

B. S. Kaith; Kiran Kumar

2007-01-01

393

How to remove the influence of trace water from the absorption spectra of SWNTs dispersed in ionic liquids  

PubMed Central

Summary Single-walled carbon nanotubes (SWNTs) can be efficiently dispersed in the imidazolium-based ionic liquids (ILs), at relatively high concentration, with their intrinsic structure and properties retained. Due to the hygroscopicity of the ILs, water bands may be introduced in the absorption spectra of IL-dispersed SWNTs and cause problems in spectral deconvolution and further analysis. In order to remove this influence, a quantitative characterization of the trace water in [BMIM]+[PF6]? and [BMIM]+[BF4]? was carried out by means of UV–vis-NIR absorption spectroscopy. A simple yet effective method involving spectral subtraction of the water bands was utilized, and almost no difference was found between the spectra of the dry IL-dispersed SWNT samples treated under vacuum for 10 hours and the spectra of the untreated samples with subtraction of the pure water spectrum. This result makes it more convenient to characterize SWNTs with absorption spectra in the IL-dispersion system, even in the presence of trace amount of water. PMID:22003471

Zhang, Daqi

2011-01-01

394

Experimental Investigations on the Characteristics of the Ammonia-Water Absorption Refrigerator for Low Temperature Solution Cycle  

NASA Astrophysics Data System (ADS)

This report refers to some static characteristics of the ammonia-water absorption refrigerator for low temperature refrigerating process which needs the temperature below the freezing point. Especially, the influence of evaporating temperature and cooling water temperature is clarified by the experimental investigation. In addition to this, the validity of constructed simulation model of this absorption refrigerator is mentioned. The validity of simulation model is verified by the comparison of experimental results and calculation. To examine the characteristics, we conducted the performance test using the trial product of which the standard cooling capacity is 175kW. The performance is estimated according to cooling capacity and COP. As a result, the effects of the evaporating temperature and cooling water temperature on the cooling performance are clarified by the experimental research. Furthermore, the calculation of the static characteristics predicted by the simulation model is in good agreements with the experimental results.

Takei, Toshitaka; Kimijima, Shinji; Saito, Kiyoshi; Kawai, Sunao

395

The dynamic viscoelasticity and water absorption characteristics of soft acrylic resin materials containing adipates and a maleate plasticizer.  

PubMed

The purpose of this study was to investigate the use of different plasticizers in soft acrylic resin materials to reduce leaching of the plasticizer and thus increase the durability of tissue conditioners. Samples were prepared containing different combinations of three types of polymer/copolymer powder and four types of plasticizer liquid (DEHM, DIBA, DAA and DINA). The dynamic viscoelasticity of each sample was measured after water immersion using a dynamic mechanical analyzer. Water absorption, solubility and weight change were also measured. A significant difference was found among the materials regarding dynamic viscoelasticity, water absorption and solubility. The samples containing P-n-BMA had the most stable G' and G'' scores throughout the immersion. P-n-BMA is the most suitable powder together with DEHM as the most suitable liquid component for a tissue conditioner. These results suggest that it is possible to improve the durability of tissue conditioners by combining different polymers and plasticizers. PMID:22277618

Hong, Guang; Tsuka, Hiroki; Maeda, Takeshi; Akagawa, Yasumasa; Sasaki, Keiichi

2012-02-01

396

Recent advances in carrier-mediated intestinal absorption of water-soluble vitamins.  

PubMed

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

Said, Hamid M

2004-01-01

397

New absorption-based optode for the detection of Hg(II) in water  

NASA Astrophysics Data System (ADS)

The current paper describes a novel absorption-based optode for mercury (II) detection. The dye 2-(5-amino-3,4-dicyano- 2H-pyrrol-2-ylidene)-1,1,2-tricyanoethanide (L') is a specific ligand for Hg2+ in water, undergoing a color change from violet to blue on the formation of the corresponding monochelated complex HgL. The dye L' was fixed on different supports by means of anionic exchange. Controlled pore glasses, cross-linked styrene and cellulose paper were used as supports and two different optode configurations were developed in order to couple them to the optical fibers. Photodegradation and leakage of the dye were thoroughly investigated by means of an accurate spectrophotometric analysis in the presence of mercury acetate [Hg(AcO)2] solutions. In order to reduce the photodegradation of the dye, an optoelectronic unit was developed using light-emitting diodes as sources and a suitable electronic circuit as the detecting system.

Baldini, Francesco; Falai, Alida; Flamini, Alberto; Mencaglia, Andrea A.

1999-02-01

398

Ultra Narrowband Optical Filters for Water Vapor Differential Absorption Lidar (DIAL) Atmospheric Measurements  

NASA Technical Reports Server (NTRS)

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.

Stenholm, Ingrid; DeYoung, Russell J.

2001-01-01

399

Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.  

PubMed

We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow. PMID:20721033

Svensson, Tomas; Lewander, Märta; Svanberg, Sune

2010-08-01

400

Solid phase extraction and graphite furnace atomic absorption spectrometric determination of ultra trace amounts of bismuth in water samples.  

PubMed

A simple and reliable method for the selective extraction and determination of bismuth in water as well as alloy samples using octadecyl bonded silica cartridge modified with cyanex 301 and graphite furnace atomic absorption spectrometry is described. Extraction efficiency and influence of sample matrix, optimum amount of extraction ligand, type and least amount of proper eluent and flow rates were evaluated. The limit of detection of the proposed method is 0.01 ng ml(-1). The influence of potential interfering cations in water samples on the recovery of bismuth was investigated. The method was successfully applied to the extraction and determination of bismuth in natural water and alloy samples. PMID:18968557

Yamini, Yadollah; Chaloosi, Marzieh; Ebrahimzadeh, Homeira

2002-03-11

401

Measuring absorption coefficients in small volumes of highly scattering media: source-detector separations for which path lengths do not depend on scattering properties  

SciTech Connect

The noninvasive measurement of variations in absorption that are due to changes in concentrations of biochemically relevant compounds in tissue is important in many clinical settings. One problem with such measurements is that the path length traveled by the collected light through the tissue depends on the scattering properties of the tissue. We demonstrate, using both Monte Carlo simulations and experimental measurements, that for an appropriate separation between light-delivery and light-collection fibers the path length of the collected photons does not depend on scattering parameters for the range of parameters typically found in tissue. This is important for developing rapid, noninvasive, and inexpensive methods for measuring absorption changes in tissue. {copyright} 1997 Optical Society of America

Mourant, J.R.; Bigio, I.J.; Jack, D.A.; Johnson, T.M.; Miller, H.D. [Bioscience and Biotechnology Group CST-4, MS E535, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-08-01

402

Water-vapor absorption line measurements in the 940-nm band by using a Raman-shifted dye laser.  

PubMed

We report water-vapor absorption line measurements that are made by using the first Stokes radiation (930-982 nm) with HWHM 0.015 cm(-1) generated by a narrow-linewidth, tunable dye laser. Forty-five absorption line strengths are measured with an uncertainty of 6% and among them are fourteen strong lines that are compared with previous measurements for the assessment of spectral purity of the light source. Thirty air-broadened linewidths are measured with 8% uncertainty at ambient atmospheric pressure with an average of 0.101 cm(-1). The lines are selected for the purpose of temperature-sensitive or temperature-insensitive lidar measurements. Results for these line strengths and linewidths are corrected for broadband radiation and finite laser linewidth (0.015 cm(-1) HWHM) broadening effects and compared with the high-resolution transmission molecular absorption. PMID:20802779

Chu, Z; Wilkerson, T D; Singh, U N

1993-02-20

403

The influence of recycled expanded polystyrene (EPS) on concrete properties: Influence on flexural strength, water absorption and shrinkage  

NASA Astrophysics Data System (ADS)

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.

Elsalah, Jamaleddin; Al-Sahli, Yosra; Akish, Ahmed; Saad, Omar; Hakemi, Abdurrahman

2013-12-01

404

WVR-GPS comparison measurements and calibration of the 20-32 GHz tropospheric water vapor absorption model.  

SciTech Connect

Collocated measurements of opacity (from water vapor radiometer brightness temperatures) and wet path delay (from ground-based tracking of global positioning satellites) are used to constrain the model of atmospheric water vapor absorption in the 20-32 GHz band. A differential approach is presented in which the slope of opacity-versus-wet delay data is used as the absorption model constraint. This technique minimizes the effects of radiometric calibration errors and oxygen model uncertainties in the derivation of a best-fit vapor absorption model. A total of approximately five months of data was obtained from two experiment sites. At the Cloud and Radiation Testbed (CART) site near Lamont, Oklahoma, three independent water vapor radiometers (WVRs) provided near-continuous opacity measurements over the interval July-September 1998. At the NASA/Goldstone tracking station in the California desert two WVRs; obtained opacity data over the September-October 1997 interval. At both sites a Global Positioning Satellite (GPS) receiver and surface barometer obtained the data required for deriving the zenith wet delays over the same time frames. Measured values of the opacity-versus-wet delay slope parameter were obtained at four WVR frequencies (20.7, 22.2, 23.8, and 31.4 GHz) and compared with predictions of four candidate absorption models referenced in the literature. With one exception, all three models provide agreement within 5% of the opacity-versus-wet delay slope measurements at all WVR frequencies at both sites. One model provides agreement for all channels at both sites to the 2-3% level. This absorption model accuracy level represents a significant improvement over that attainable using radiosondes.

Keihm, S. J.; Bar-Server, Y.; Liljegren, J. C.; Environmental Research; NASA

2002-06-01

405

Role of glucose transporters in the intestinal absorption of gastrodin, a highly water-soluble drug with good oral bioavailability.  

PubMed

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

Cai, Zheng; Huang, Juan; Luo, Hui; Lei, Xiaolu; Yang, Zhaoxiang; Mai, Yang; Liu, Zhongqiu

2013-07-01

406

The role of skin absorption as a route of exposure for volatile organic compounds (VOCs) in drinking water.  

PubMed Central

Assessments of drinking water safety rely on the assumption that ingestion represents the principal route of exposure. A review of the experimental literature revealed that skin penetration rates for solvents are remarkably high, and that the stratum corneum is a less effective barrier to penetration than traditionally assumed. Based on published skin absorption rates, we used Fick's law (Jos = Kop delta Cos) to determine permeability constants for selected compounds. We then calculated dose per kilogram for nine different exposure situations and compared this to the oral dose per kilogram. We found that skin absorption contributed from 29-91 per cent of the total dose, averaging 64 per cent. Dose per kilogram body weight ranged from .0002 mg/kg-.18 mg/kg, with an average of .03 mg/kg. In weak aqueous solutions, flux of the solute is directly proportional to concentration. Laboratory approaches differ markedly from environmental exposures and can underestimate absorption. We conclude that skin absorption of contaminants in drinking water has been underestimated and that ingestion may not constitute the sole or even primary route of exposure. PMID:6711723

Brown, H S; Bishop, D R; Rowan, C A

1984-01-01

407

The choice of models relating tritiated water absorption to subepithelial blood flow in the rumen of sheep.  

PubMed Central

1. The blood flow to the ruminoreticulum of anaesthetized sheep was varied by changing the proportion of CO2 in the gas stirring solutions confined to this organ. 2. Clearance of tritiated water was thereby varied fourfold, from 10 to 44ml./min.100 g epithelium, with negligible net water movement. 4. Subepithelial blood flow, observed with radioactive microspheres using the reference organ technique, varied tenfold, from 20 to 200 ml./min.100 g epithelium. 4. The relation between tritiated water absorption and blood water flow was approximated by a hyperbolic model, but was appreciably better described using a higher order term in blood flow consistent with a countercurrent exchange of tritiated water between arterioles and venules. 5. The distribution of blood flow between different regions of the organ and between epithelium and muscle is described. PMID:536905

Dobson, A

1979-01-01

408

Radiation effects in water ice: A near-edge x-ray absorption fine structure study  

SciTech Connect

The changes in the structure and composition of vapor-deposited ice films irradiated at 20 K with soft x-ray photons (3-900 eV) and their subsequent evolution with temperatures between 20 and 150 K have been investigated by near-edge x-ray absorption fine structure spectroscopy (NEXAFS) at the oxygen K edge. We observe the hydroxyl OH, the atomic oxygen O, and the hydroperoxyl HO{sub 2} radicals, as well as the oxygen O{sub 2} and hydrogen peroxide H{sub 2}O{sub 2} molecules in irradiated porous amorphous solid water (p-ASW) and crystalline (I{sub cryst}) ice films. The evolution of their concentrations with the temperature indicates that HO{sub 2}, O{sub 2}, and H{sub 2}O{sub 2} result from a simple step reaction fuelled by OH, where O{sub 2} is a product of HO{sub 2} and HO{sub 2} a product of H{sub 2}O{sub 2}. The local order of ice is also modified, whatever the initial structure is. The crystalline ice I{sub cryst} becomes amorphous. The high-density amorphous phase (I{sub a}h) of ice is observed after irradiation of the p-ASW film, whose initial structure is the normal low-density form of the amorphous ice (I{sub a}l). The phase I{sub a}h is thus peculiar to irradiated ice and does not exist in the as-deposited ice films. A new 'very high density' amorphous phase--we call I{sub a}vh--is obtained after warming at 50 K the irradiated p-ASW ice. This phase is stable up to 90 K and partially transforms into crystalline ice at 150 K.

Laffon, C.; Lacombe, S.; Bournel, F.; Parent, Ph. [Laboratoire de Chimie-Physique, Matiere et Rayonnement, UMR 7614, Universite Pierre et Marie Curie et CNRS, 11 Rue Pierre et Marie Curie, 75231 Paris, Cedex 05 (France); Laboratoire des Collisions Atomiques et Moleculaires, UMR 8625, Universite Paris Sud 11, 91405 Orsay Cedex (France); Laboratoire de Chimie-Physique, Matiere et Rayonnement, UMR 7614, Universite Pierre et Marie Curie et CNRS, 11 Rue Pierre et Marie Curie, 75231 Paris, Cedex 05 (France)

2006-11-28

409

Perfecting a method of micro-analysis of water and acetic acid in a cocoa bean in the course of drying: applying to determine transportation coefficients  

NASA Astrophysics Data System (ADS)

This article is about the study of the diffusion of water and acetic acid in a grain of cocoa in course of drying. The authors present a method of microanalysis which enables the analysis of each little slice of the grain : a precise measurement of each slice is realised in view of the analysis from the centre to the surface of the grain with the aid of a cutting apparatus, designed and realised to this effect. At each instant of the drying process, the profiles of water and acetic acid contents are then determined. A one dimensional diffusion model enables a shell by shell evaluation of the diffusion of water and acid in the cocoa grain. The results obtained show an augmentation of transport coefficients in course of drying. We however observe a decrease of the diffusion coefficient of water to the low moisture content : what makes us think of the appearance of crusting phenomenon.

Nganhou, J.; Njomo, D.; Bénet, J. C.; Augier, F.; Berthomieu, G.

2003-09-01

410

Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems  

NASA Astrophysics Data System (ADS)

The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

Korenman, Ya. I.; Krivosheeva, O. A.; Mokshina, N. Ya.

2012-12-01

411

Moisture absorption and absorption kinetics in polyelectrolyte films: influence of film thickness.  

PubMed

Specular X-ray reflectivity (XR) and quartz crystal microbalance (QCM) measurements were used to determine the absorption of water into thin poly(4-ammonium styrenesulfonic acid) films from saturated vapor at 25 degrees C. The effect of film thickness on the absorption kinetics and overall absorption was investigated in the range of thickness from (3 to 200) nm. The equilibrium swelling of all the films irrespective of film thickness was (0.57+/-0.03) volume fraction. Although the equilibrium absorption is independent ofthickness, the absorption rate substantially decreases for film thickness < 100 nm. For the thinnest film (3 nm), there is a 5 orders of magnitude decrease in the diffusion coefficient for water. PMID:15803734

Vogt, Bryan D; Soles, Christopher L; Lee, Hae-Jeong; Lin, Eric K; Wu, Wen-Li

2004-02-17

412

Water vapor differential absorption lidar measurements using a diode-pumped all-solid-state laser at 935 nm  

Microsoft Academic Search

A diode-pumped, single-frequency laser system emitting at 935 nm has recently been developed to serve as the transmitter for\\u000a water vapor differential absorption lidar (DIAL) measurements. This laser uses Nd:YGG (Y3Ga5O12) as the active medium and emits radiation directly at 935 nm without the need of additional frequency conversion processes.\\u000a The system was diode-pumped at 806 nm and was built up in

A. Fix; G. Ehret; J. Löhring; D. Hoffmann; M. Alpers

2011-01-01

413

A diode-pumped Cr:LiSAF laser for UAV-based water vapor differential absorption lidar (DIAL)  

Microsoft Academic Search

An autonomous, compact, high-energy, injection seeded, diode-pumped, tunable Cr:LiSAF laser for a water vapor differential absorption lidar (DIAL) system deployed on a high-altitude unpiloted airborne vehicle (UAV) has been developed. A unique laser resonator, consisting of a Cr:LiSAF slab pumped by 8 high-power diode bar stacks in a total internal reflection configuration, provides high extraction efficiency and good laser beam

Coorg R. Prasad; Viktor A. Fromzel; Joseph S. Smucz; In H. Hwang; William E. Hasselbrack

2000-01-01

414

Application of Temperature-Dependent Fluorescent Dyes to the Measurement of Millimeter Wave Absorption in Water Applied to Biomedical Experiments  

PubMed Central

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects. PMID:25435859

Popenko, Oleksandr

2014-01-01

415

Simultaneous Determination of Trace Heavy Metals in Waters by Atomic Absorption Spectrometry After Preconcentration by Solvent Extraction  

Microsoft Academic Search

A simple and rapid method for the simultaneous extraction of heavy metals using a new reagent 5-(2?-carbomethoxyphenyl; azo-8-quinolinol(R) into methyl isobutyl. ketone (MIBK) and their subsequent determination by flame atomic absorption spectrometry is described. The method has been applied to the determination of Cu. Pb, Ni, Fe, Cr, Co and Mo in drinking and bore well waters. The extraction has

R. Saran; T. S. Basu Baul; P. Srinivas; D. T. Khathing

1992-01-01

416

Application of temperature-dependent fluorescent dyes to the measurement of millimeter wave absorption in water applied to biomedical experiments.  

PubMed

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects. PMID:25435859

Kuzkova, Nataliia; Popenko, Oleksandr; Yakunov, Andrey

2014-01-01

417

QSPR modelling of normal boiling points and octanol\\/water partition coefficient for acyclic and cyclic hydrocarbons using SMILES-based optimal descriptors  

Microsoft Academic Search

Predictive quantitative structure - property relationships (QSPR) have been established for normal boiling points and octanol\\/water\\u000a partition coefficient for acyclic and cyclic hydrocarbons using optimal descriptors calculated with simplified molecular input\\u000a line entry system (SMILES). The probabilistic criteria for a rational definition of the domain of applicability of these models\\u000a are discussed.

A. A. Toropov; A. P. Toropova; E. Benfenati

2010-01-01

418

Evaluation and management of the impact of land use change on the nitrogen and phosphorus load delivered to surface waters: the export coefficient modelling approach  

Microsoft Academic Search

A manageable, relatively inexpensive model was constructed to predict the loss of nitrogen and phosphorus from a complex catchment to its drainage system. The model used an export coefficient approach, calculating the total nitrogen (N) and total phosphorus (P) load delivered annually to a water body as the sum of the individual loads exported from each nutrient source in its

P. J. Johnes

1996-01-01

419

Air-Liquid Partition Coefficient for a Diverse Set of Organic Compounds: Henry?s Law Constant in Water and Hexadecane  

EPA Science Inventory

The SPARC vapor pressure and activity coefficient models were coupled to estimate Henry?s Law Constant (HLC) in water and in hexadecane for a wide range of non-polar and polar solute organic compounds without modification to/or additional parameterization of the vapor pressure or...

420

Water vapor absorption in porous media polluted by calcium nitrate studied by time domain nuclear magnetic resonance.  

PubMed

Nuclear magnetic resonance relaxation analysis of liquid water (1)H nuclei in real porous media, selected for their similar composition (carbonate rocks) and different pore space architecture, polluted with calcium nitrate, is presented to study the kinetics of water condensation and salt deliquescence inside the pore space. These phenomena are responsible for deterioration of porous materials when exposed to environmental injury by pollution in a humid atmosphere. The theory is well described for simple pore geometries, but it is not yet well understood in real porous media with wide distributions of pore sizes and connections. The experiment is performed by following in time the formation of liquid water inside the pore space by T(1) and T(2) relaxation time distributions. The distributions allow one to see the effects of both the salt concentration and the pore space structure on the amount of water vapor condensed and its kinetics. It is shown that, for a given lithotype, even with different amounts of pollutant, the rate-average relaxation time T(1ra) tends to increase monotonically with NMR signal, proportional to the amount of liquid water. T(1ra) is often inversely associated with surface-to-volume ratio. This suggests a trend toward the filling of larger pores as amounts of liquid water increase, but it does not indicate a strict sequential filling of pores in order of size and starting with the smallest; in fact, relaxation time distributions show clearly that this is not the case. Increased amounts of salt lead to both markedly increased rates and markedly increased amounts of water absorption. NMR measurements of amounts of water, together with relaxation time distributions, give the possibility of information on the effect of pollution in porous materials exposed to humid atmospheres but sheltered from liquid water, even before the absorption of large amounts of moisture and subsequent damage. These phenomena are of importance also in other fields, such as the exploitation of geothermal energy. PMID:19594125

Gombia, Mirko; Bortolotti, Villiam; Brown, Robert J S; Camaiti, Mara; Cavallero, Luisa; Fantazzini, Paola

2009-08-01

421

BELINDA: Broadband Emission Lidar with Narrowband Determination of Absorption. A new concept for measuring water vapor and temperature profiles  

NASA Technical Reports Server (NTRS)

We present a new concept for differential absorption lidar measurements of water vapor and temperature profiles. The idea is to use one broadband emission laser and a narrowband filter system for separation of the 'online' and 'offline' return signals. It is shown that BELINDA offers improvements as to laser emission shape and stability requirements, background suppression, and last and most important a significant reduction of the influence of Rayleigh scattering. A suitably designed system based on this concept is presented, capable of measuring water vapor or temperature profiles throughout the planetary boundary layer.

Theopold, F. A.; Weitkamp, C.; Michaelis, W.

1992-01-01

422

BELINDA: Broadband Emission Lidar with Narrowband Determination of Absorption. A new concept for measuring water vapor and temperature profiles  

NASA Astrophysics Data System (ADS)

We present a new concept for differential absorption lidar measurements of water vapor and temperature profiles. The idea is to use one broadband emission laser and a narrowband filter system for separation of the 'online' and 'offline' return signals. It is shown that BELINDA offers improvements as to laser emission shape and stability requirements, background suppression, and last and most important a significant reduction of the influence of Rayleigh scattering. A suitably designed system based on this concept is presented, capable of measuring water vapor or temperature profiles throughout the planetary boundary layer.

Theopold, F. A.; Weitkamp, C.; Michaelis, W.

1992-07-01

423

EXTENSION OF THE INVERSE ADDING-DOUBLING METHOD TO THE MEASUREMENT OF WAVELENGTH-DEPENDENT ABSORPTION AND SCATTERING COEFFICIENTS OF BIOLOGICAL SAMPLES  

SciTech Connect

Light interaction with biological tissue can be described using three parameters: the scattering and absorption coeffi cients (?s and ?a), as well as the anisotropy (g) which describes the directional dependence of the scattered photons. Accurately determining these optical properties for different tissue types at specifi c wavelengths simultaneously would be benefi cial for a variety of different biomedical applications. The goal of this project was to take a user defi ned g-value and determine the remaining two parameters for a specifi ed wavelength range. A fully automated computer program and process was developed to collect data for all wavelengths in a timely and accurate manner. LabVIEW® was used to write programs to automate raw intensity data collection from a spectrometer equipped integrating sphere, conversion of the data into a format for analysis via Scott Prahl’s Inverse Adding-Doubling (IAD) C code execution, and fi nally computation of the optical properties based on the output from the IAD code. To allow data to be passed effi ciently between LabVIEW® and C code program modules, the two were combined into a single program (OPT 3.1). OPT 3.1 was tested using tissue mimicking phantoms. Determination of the absorption and scattering coeffi cients showed excellent agreement with theory for wavelengths where the user inputted single g-value was suffi ciently precise. Future improvements entail providing for multi-wavelength g-value entry to extend the accuracy of results to encompass the complete multispectral range. Ultimately, the data collection process and algorithms developed through this effort will be used to examine actual biological tissues for the purpose of building and refi ning models for light-tissue interactions.

Allegood, M.S.; Baba, J.S.

2008-01-01

424

Chloride and water secretion and absorption by the gills of the eel  

Microsoft Academic Search

Perfusion experiments with the heart-gill preparation of the common eel, Anguilla vulgaris, are presented. Various concentrations of perfusion medium were used with eels from both sea water and fresh water. The external medium was sea water in the case of the sea water eels and fresh water in the other case.

Ancel B. Keys

1931-01-01

425

MODELING THE OCTANOL-WATER PARTITION COEFFICIENT OF SUBSTITUTED PHENOLS BY THE USE OF STRUCTURE INFORMATION MODELING THE OCTANOL-WATER PARTITION COEFFICIENT OF SUBSTITUTED PHENOLS BY THE USE OF STRUCTURE INFORMATION  

Microsoft Academic Search

0.9457 0.9890 CI r_(lower, upper) (95% confidence intervals) (0.8897, 0.9740) (0.9767, 0.9948) r 2 (squared correlation coefficient) 0.8943 0.9781 r 2 adj (adjusted correlation coefficient) 0.8865 0.9745 s est (standard error) 0.3671 0.1739 F est (Fisher parameter of regression model ) 114 279 pest (F significance) < 0.0001 < 0.0001 r 2 cv-loo (cross -validation loo squared correlation coefficient) 0.8660

Lorentz JÄNTSCHI; Sorana-Daniela BOLBOAC

2005-01-01

426

Wheat Irrigation Management Using Multispectral Crop Coefficients: II. Irrigation Scheduling Performance, Grain Yield, and Water Use Efficiency  

Technology Transfer Automated Retrieval System (TEKTRAN)

Current irrigation scheduling is based on well-established crop coefficient-reference evapotranspiration methods. However, appropriate irrigation scheduling can be negated when crop evapotranspiration (ETc) is poor due to imprecise crop coefficients. The premise of this research is that real-time mo...

427

The emission coefficient of uranium plasmas  

NASA Technical Reports Server (NTRS)

The emission coefficient for uranium plasmas (Temperature: 8000 K) was measured for the wavelength range (200 A - 6000 A). The results are compared to theory and other measurements. The absorption coefficient for the same wavelength interval is also given.

Schneider, R. T.; Campbell, H. D.; Mack, J. M.

1973-01-01

428

Bicarbonate secretion plays a role in chloride and water absorption of the European flounder intestine.  

PubMed

Experiments performed on isolated intestinal segments from the marine teleost fish, the European flounder (Platichthys flesus), revealed that the intestinal epithelium is capable of secondary active HCO3(-) secretion in the order of 0.2-0.3 micromol x cm(-2) x h(-1) against apparent electrochemical gradient. The HCO3(-) secretion occurs via anion exchange, is dependent on mucosal Cl(-), results in very high mucosal HCO3(-) concentrations, and contributes significantly to Cl(-) and fluid absorption. This present study was conducted under in vivo-like conditions, with mucosal saline resembling intestinal fluids in vivo. These conditions result in a transepithelial potential of -16.2 mV (serosal side negative), which is very different from the -2.2 mV observed under symmetrical conditions. Under these conditions, we found a significant part of the HCO3(-) secretion is fueled by endogenous epithelial CO2 hydration mediated by carbonic anhydrase because acetazolamide (10(-4) M) was found to inhibit HCO3(-) secretion and removal of serosal CO(2) was found not to influence HCO3(-) secretion. Reversal of the epithelial electrochemical gradient for Cl(-) (removal of serosal Cl(-)) and elevation of serosal HCO3(-) resulted in enhanced HCO3(-) secretion and enhanced Cl(-) and fluid absorption. Cl(-) absorption via an anion exchange system appears to partly drive fluid absorption across the intestine in the absence of net Na(+) absorption. PMID:15576660

Grosell, M; Wood, C M; Wilson, R W; Bury, N R; Hogstrand, C; Rankin, C; Jensen, F B

2005-04-01

429

Ultrasonic absorption in liquid metals at the melting temperature  

NASA Astrophysics Data System (ADS)

The Stokes-Kirchhoff theory is used to study the ultrasound absorption coefficient in 33 liquid metals (25 metals are analyzed for the first time) at the melting temperature. A relation between the absorption coefficient and the conduction electron concentration is found. The ratio of the absorption coefficient caused by heat conduction to the absorption coefficient caused by viscosity is estimated.

Tekuchev, V. V.; Svezhintsev, E. N.; Ivanova, I. V.

2014-03-01

430

Morphological correlate of regional partitioning of integumental water absorption in terrestrial slugs.  

PubMed

An ultrastructural study of the foot surface of the terrestrial mollusc, Limax maximus, has revealed a correlation of epithelial cell type with the functional partitioning of the surface. The lateral absorptive bands of the foot are comprised exclusively of microvillar epithelial cells, while those of the medial locomotor band are all ciliated. Thus, there is a clear partitioning of epithelial cell types between areas of the foot surface with distinct functional roles. Consistent with the proposed role for paracellular absorption, varying states of hydration are shown to affect the extent of the intercellular spaces, but not the intracellular architecture. PMID:8073419

Prior, D J; Maugel, T K; Sellers, M

1994-06-01

431

Experimental Study on Temperature Coefficient of Reactivity in Light-Water-Moderated and Heavy-Water-Reflected Cylindrical Core Loaded with Highly-Enriched-Uranium or Medium-Enriched-Uranium Fuel  

Microsoft Academic Search

By using the Kyoto University Critical Assembly (KUCA), a series of critical experiments was performed to measure the temperature coefficient of reactivity in a light-water-moderated and heavy-water-reflected cylindrical core loaded with highly-enriched-uranium (HEU) or medium- enriched-uranium (MEU) fuel. The measurement was performed for the approximately 20 to 70°C range to examine the effects of the size of light-water region in

Seiji SHIROYA; Masaaki MORI; Tsuyoshi MISAWA; Masatoshi HAYASHI; Keiji KOBAYASHI; Keiji KANDA

1995-01-01

432

Very high finesse optical-feedback cavity-enhanced absorption spectrometer for low concentration water vapor isotope analyses.  

PubMed

So far, cavity-enhanced absorption spectroscopy (CEAS) has been based on optical cavities with a high finesse F that, however, has been limited by mirror reflectivity and by cavity transmission considerations to a few times 10,000. Here, we demonstrate a compact near-infrared optical-feedback CEAS instrument for water vapor isotope ratio measurements, with F>140,000. We show that this very high finesse can be effectively exploited to improve the detection sensitivity to the full extent predicted by the increased effective path length to reach a noise equivalent absorption sensitivity of 5.7×10(-11)??cm(-1)?Hz(-1/2) for a full spectrum registration (including possible effects of interference fringes and fit model inadequacies). PMID:24686607

Landsberg, J; Romanini, D; Kerstel, E

2014-04-01

433

Determination of trace silver in water samples by online column preconcentration flame atomic absorption spectrometry using termite digestion product.  

PubMed

A new method for Ag determination in water samples using solid phase extraction (SPE) coupled to a flow injection system and flame atomic absorption spectrometry was developed. The sorbent used for Ag preconcentration and extraction was the termite digestion product. Flow and chemical variables of the system were optimized through a multivariate procedure. The factors selected were adsorbent mass, buffer type and concentration, sample pH, and sample flow rate. The detection limit and precision were 3.4??g?L(-1) and 3.8% (n = 6, 15??g?L(-1)), respectively. The enrichment factor