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1

Absorption coefficient of CDOM in Zhejiang coastal waters  

NASA Astrophysics Data System (ADS)

Chromophoric dissolved organic matter (CDOM) exists in all natural waters. Researches on optical properties of CDOM play an important role in ocean color remote sensing retrieval. The optical properties of CDOM in Zhejiang coastal waters were investigated from August 18, 2009 to June 9, 2011 covering four seasons. Based on the measured data, the distribution of the absorption coefficient of CDOM was analyzed. The results showed that absorption coefficient at 440 nm (a(440)) decreased with the offshore direction, and the relatively high value of a(440) was observed generally in the coastal waters and low value in the adjacent waters. The distribution reflected the terrigenous origin characteristics of CDOM. The relationship between salinity and a(440) of the four seasons was discussed. The results demonstrated that a(440) had a significant negative linear relationship with the salinity. That is to say, CDOM took on the conservative behavior in the research region.

Fan, Guannan; Mao, Zhihua; Chen, Peng; Huang, Haiqing

2013-09-01

2

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

Microsoft Academic Search

Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are

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

1993-01-01

3

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

Microsoft Academic Search

Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source

William B. Grant

1990-01-01

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

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

PubMed

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

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

2011-09-30

6

Parameterization of the Mie Extinction and Absorption Coefficients for Water Clouds.  

NASA Astrophysics Data System (ADS)

It was found that the anomalous diffraction approximation (ADA) could be made to approximate Mie theory for absorption and extinction in water clouds by parameterizing the missing physics: 1) internal reflection/refraction, 2) photon tunneling, and 3) edge diffraction. Tunneling here refers to processes by which tangential or grazing photons beyond the physical cross section of a spherical particle may be absorbed. Contributions of the above processes to extinction and/or absorption were approximated in terms of particle size, index of refraction, and wavelength. It was found that tunneling can explain most of the difference between ADA and Mie theory for water clouds in the thermal IR.The modified ADA yielded analytical expressions for the absorption and extinction efficiencies, Qabs and Qext, which were integrated over a gamma size distribution to yield expressions for the absorption and extinction coefficients, abs and ext. These coefficients were expressed in terms of the three gamma distribution parameters, which were related to measured properties of the size distribution: liquid water content, mean, and mass-median diameter. Errors relative to Mie theory for abs and ext were generally 10% for the effective radius range in water clouds of 5-30 m, for any wavelength in the solar or terrestrial spectrum. For broadband emissivities and absorptivities regarding terrestrial and solar radiation, the errors were less than 1.2% and 4%, respectively. The modified ADA dramatically reduces computation times relative to Mie theory while yielding reasonably accurate results.

Mitchell, David L.

2000-05-01

7

Power absorption coefficient constants for water, acetonitrile, and methylene chloride at far infrared wavelengths  

NASA Astrophysics Data System (ADS)

The problem of multiple internal reflections within the windows of an optical cell is analysed using Abele's matrix method. The Beer-Lambert power law is modified by the standing waves formed in between the cell and the detector. Power absorption coefficient of a material is calculated by a fit to the modified version of the equation. Precise ? values for water, acetonitrile and methylene chloride are calculated at far infrared wavelengths using a molecular laser source.

Vij, J. K.

1989-07-01

8

Parameterization of the Mie extinction and absorption coefficients for water clouds  

SciTech Connect

It was found that the anomalous diffraction approximation (ADA) could be made to approximate Mie theory for absorption and extinction in water clouds by parameterizing the missing physics: (1) internal reflection/refraction, (2) photon tunneling, and (3) edge diffraction. Tunneling here refers to processes by which tangential or grazing photons beyond the physical cross section of a spherical particle may be absorbed. Contributions of the above processes to extinction and/or absorption were approximated in terms of particle size, index of refraction, and wavelength. It was found that tunneling can explain most of the difference between ADA and Mie theory for water clouds in the thermal IR. The modified ADA yielded analytical expressions for the absorption and extinction efficiencies, Q{sub abs} and Q{sub ext}, which were integrated over a gamma size distribution to yield expressions for the absorption and extinction coefficients, {beta}{sub abs} and {beta}{sub ext}. These coefficients were expressed in terms of the three gamma distribution parameters, which were related to measured properties of the size distribution: liquid water content, mean, and mass-median diameter. Errors relative to Mie theory for {beta}{sub abs} and {beta}{sub ext} were generally {le}10% for the effective radius range in water clouds of 5--30 {micro}m, for any wavelength in the solar or terrestrial spectrum. For broadband emissivities and absorptivities regarding terrestrial and solar radiation, the errors were less than 1.2% and 4%, respectively. The modified ADA dramatically reduces computation times relative to Mie theory while yielding reasonably accurate results.

Mitchell, D.L.

2000-05-01

9

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

PubMed

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

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

2011-12-01

10

Specific absorption and backscatter coefficient signatures in southeastern Atlantic coastal waters  

NASA Astrophysics Data System (ADS)

Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Florida. Stations were also occupied in near coastal waters out to the edge of the Gulf Stream in the vicinity of Kennedy Space Center, Florida and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting optical cross section signatures suggest different models are needed for the different water types and that the common linear model may only appropriate for coastal and oceanic water types. Mean particle size estimates based on the optical cross section, suggest as expected, that particle size of oceanic particles are smaller than more turbid water types. The data discussed and presented are necessary for remote sensing applications of sensors as well as for development and inversion of remote sensing algorithms.

Bostater, Charles R.

1998-12-01

11

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

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

12

Determination of the partition coefficients and absorption kinetic parameters of chemicals in a lipophilic membrane\\/water system by using a membrane-coated fiber technique  

Microsoft Academic Search

The absorption kinetics of chemicals in a lipophilic membrane\\/water system was studied with a membrane-coated fiber (MCF) technique, in which the partition coefficient, membrane diffusivity and boundary layer adjacent to the membrane were taken into account. The cumulative amount permeated into the membrane was expressed as a function of absorption time in an exponential equation. Two constants were introduced into

Xin-Rui Xia; Ronald E. Baynes; Nancy A. Monteiro-Riviere; Jim E. Riviere

2005-01-01

13

Nitrogen Dioxide Absorption Coefficients at High Temperatures.  

National Technical Information Service (NTIS)

The absorption coefficient of nitrogen dioxide, NO2, is used in models of the fireball resulting from atmospheric nuclear detonations. This report gives values for the absorption coefficient obtained at wavelengths between 380 and 760 nm and at temperatur...

D. E. Paulsen R. E. Huffman

1976-01-01

14

Determination of lipid bilayer\\/water partition coefficient of new phenothiazines using the second derivative of absorption spectra method  

Microsoft Academic Search

The partition coefficients (Kp) between lipid bilayer of phosphatidylcholine (PC) vesicles and buffer for five new phenothiazines were determined using the second derivatives of ultraviolet absorption spectra. The ?max of absorption band for each of the investigated phenothiazine derivatives (PDs) was shifted to the longer wavelengths in the presence of PC vesicles with increasing of lipid concentration. As a result

Andrzej Po?a; Krystyna Michalak; Anna Burliga; Noboru Motohashi; Masami Kawased

2004-01-01

15

Retrieval of absorption and backscattering coefficients from HJ-1A/CCD imagery in coastal waters.  

PubMed

A simple semi-analytical model (SAB) was developed for computing a(560) and b(b)(550) from HJ-1A/CCD images. By comparison with field measurements, the SAB model produces 5.3-23.5% uncertainty for a(560) and b(b)(550) retrievals. The a(560) and b(b)(550) are also retrieved from satellite images. The match-up analysis results indicate that a(560) and b(b)(550) may be derived from the HJ-1A/CCD images with respective uncertainties of 29.84 and 21.35%. These findings imply that, provided that an atmospheric correction scheme for the green bands is available, the extensive database of HJ-1A/CCD imagery may be used for the quantitative monitoring of optical properties in coastal waters. PMID:23482150

Chen, Jun; Quan, Wenting; Yao, Guoqing; Cui, Tingwei

2013-03-11

16

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

17

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

18

The Absorption of Incident Quanta by Atoms as Defined by the Mass Photoelectric Absorption Coefficient and the Mass Scattering Coefficient  

Microsoft Academic Search

Evidence presented indicates that the absorption of quanta as defined by the mass photoelectric absorption coefficient ??&rgr; and the mass scattering coefficient ??&rgr; of any element may be represented by a simple expression.Tabulated values of the calculated mass absorption coefficients ??&rgr; are given for wave-lengths from 0.01 to 40 angstroms for hydrogen and carbon and from 0.01 to ?K and

John A. Victoreen

1948-01-01

19

The Calculation of X-Ray Mass Absorption Coefficients  

Microsoft Academic Search

An empirical method of calculating mass absorption coefficients is given. Complete tables of constants are presented for calculating ??&rgr; for all elements and for wave-lengths less than the K critical absorption wave-length. Partial tables give constants for wave-lengths between the L1 and M1 critical wave-lengths.Calculated mass absorption coefficients are given for the common elements.

John A. Victoreen

1949-01-01

20

NUMERICAL SIMULATION OF WATER ABSORPTION IN SOFTWOOD  

Microsoft Academic Search

Whereas water can frequently come in contact with wood-based building envelope components, little work has tried to measure and model moisture uptake in orthotropic wood. This paper presents experimental results and numerical simulations of water uptake in softwood. Water absorption coefficients were measured and shown to vary according to the orientation of the fiber grain. Helium pycnometry was employed to

Luis Candanedo; Dominique Derome

2005-01-01

21

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

Microsoft Academic Search

The ammonia purification process is critical in ammonia–water absorption refrigeration systems. In this paper, a detailed\\u000a and a simplified analytical model are presented to characterize the performance of the ammonia rectification process in packed\\u000a columns. The detailed model is based on mass and energy balances and simultaneous heat and mass transfer equations. The simplified\\u000a model is derived and compared with

Jaime Sieres; José Fernández-Seara

2008-01-01

22

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

23

Solar thermal absorption heat pump breakeven coefficient of performance  

Microsoft Academic Search

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

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

1974-01-01

24

Absorption coefficient of luminescent bodies in the emission band  

Microsoft Academic Search

Einstein's theory associating the coefficients of absorption, induced emission and spontaneous emission cannot be applied to luminescent systems, because the radiative transitions occur with the absorption or emission of phonons. It may be generalised to include luminescent systems by the use of a hollow sphere whose internal walls are covered with a substance irradiated by a Wood lamp, placed at

A. Alexic; K. Nikolic; J. Buric; D. Magnant; H. Payen de La Garanderie

1982-01-01

25

Absorption coefficient of luminescent bodies in the emission band  

NASA Astrophysics Data System (ADS)

Einstein's theory associating the coefficients of absorption, induced emission and spontaneous emission cannot be applied to luminescent systems, because the radiative transitions occur with the absorption or emission of phonons. It may be generalised to include luminescent systems by the use of a hollow sphere whose internal walls are covered with a substance irradiated by a Wood lamp, placed at the centre of the sphere. From this we determine the absorption coefficient of the luminescent substance in the emission band. Work performed in part at Groupe de Physique du Solide de l'Ecole Normale Superieure.

Alexic', A.; Nikoli?, K.; Buri?, J.; Magnant, D.; de La Garanderie, H. Payen

1982-02-01

26

Absorption coefficient measurements of particle-laden filters using laser heating: Validation with nigrosin  

NASA Astrophysics Data System (ADS)

A laser-heating technique, referred as the laser-driven thermal reactor, was used in conjunction with laser transmissivity measurements to determine the absorption coefficient of particle-laden substrates (e.g., quartz-fiber filters). The novelty of this approach is that it analyzes a wide variety of specific samples (not just filtered samples) and overcomes measurement issues (e.g., absorption enhancement) associated with other filter-based particle absorption techniques. The absorption coefficient was determined for nigrosin-laden, quartz-fiber filters and the effect of the filter on the absorption measurements was estimated when compared to the isolated nigrosin results. The isolated nigrosin absorption coefficient compared favorably with Lorenz-Mie calculations for an idealized polydispersion of spherical particles (based on a measured nigronsin/de-ionized water suspension size distribution) dispersed throughout a volume equivalent to that of the nigrosin-laden filter. To validate the approach, the absorption coefficient of a nigrosin/de-ionized water suspension was in good agreement with results obtained from an ultraviolet/visible spectrometer. In addition, the estimated imaginary part of the refractive index from the Lorenz-Mie calculations compared well with literature values and was used to estimate the absorption coefficient of optically opaque packed nigrosin.

Presser, Cary

2012-05-01

27

Comparison between different spectral models of the diffuse attenuation and absorption coefficients of seawater  

NASA Astrophysics Data System (ADS)

The goal of this work is to verify different spectral models of the diffuse attenuation and absorption coefficients of sea water and to work out a recommendation for their use. It is shown that the spectral models of the diffuse attenuation coefficient Kd((lambda) ) developed by Austin, Petzold, 1984 and by Volynsky, Sud'bin, 1992 correspond with each other, as well the models of Ivanov, Shemshura, 1973 and of Kopelevich, Shemshura, 1988 for calculation of the spectral absorption coefficient a((lambda) ) on the values of Kd((lambda) ). Theoretical foundation of the relation between a((lambda) ) and Kd((lambda) ) is given. The up-to-date physical model of the sea water light absorption is considered and checked by means of comparison with measured values of the attenuation coefficient at the ultraviolet and visible spectral ranges.

Kopelevich, Oleg V.; Filippov, Yury V.

1994-10-01

28

NUMERICAL CALCULATION OF MAGNETOBREMSSTRAHLUNG EMISSION AND ABSORPTION COEFFICIENTS  

SciTech Connect

Magnetobremsstrahlung (MBS) emission and absorption play a role in many astronomical systems. We describe a general numerical scheme for evaluating MBS emission and absorption coefficients for both polarized and unpolarized light in a plasma with a general distribution function. Along the way we provide an accurate scheme for evaluating Bessel functions of high order. We use our scheme to evaluate the accuracy of earlier fitting formulae and approximations. We also provide an accurate fitting formula for mildly relativistic (kT/(m{sub e}c{sup 2}) {approx}> 0.5) thermal electron emission (and therefore absorption). Our scheme is too slow, at present, for direct use in radiative transfer calculations but will be useful for anyone seeking to fit emission or absorption coefficients in a particular regime.

Leung, Po Kin [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Gammie, Charles F. [Astronomy Department, University of Illinois, Urbana, IL 61801 (United States); Noble, Scott C., E-mail: pkleung@physics.ucsb.edu, E-mail: gammie@illinois.edu, E-mail: scn@astro.rit.edu [Center for Computational Relativity and Gravitation, School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY 14623 (United States)

2011-08-10

29

Methane Absorption Coefficients for the Jovian Planets and Titan  

NASA Astrophysics Data System (ADS)

We combined 11 data sets of methane transmission measurements within 0.4-5.5 micrometer wavelength in order to better understand the variation of methane absorption with temperature and pressure for conditions in the atmospheres of the Jovian planets and Titan. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methane absorption inside Titan's atmosphere (Tomasko et al. 2008, PSS 56, 624). We present the data with a refined analysis. The last data set consists of Hubble Space Telescope images of Jupiter taken in 2005 and 2007 as Ganymede started to be occulted by Jupiter. Using Ganymede as a light source, we probed Jupiter's stratosphere with large methane pathlengths. Below 1000 nm wavelength, we find methane absorption coefficients generally similar to those by Karkoschka (1998, Icarus 133, 134). We added descriptions of temperature and pressure dependence, which are typically small in this wavelength range. Data in this wavelength range are consistent with each other, except between 882 and 902 nm wavelength where laboratory data predict larger absorptions in the Jovian atmospheres than observed. We present possible explanations. Above 1000 nm, our analysis of the Huygens data confirms methane absorption coefficients by Irwin et al. (2006, Icarus 181, 309) at their laboratory temperatures. Huygens data are consistent with Irwin's model of the pressure dependence of methane absorption. However, when large extrapolations were needed, such as from laboratory data above 200 K to Titan's temperatures near 80 K, Irwin's model of temperature dependence predicts absorption coefficients up to 100 times lower than measured by Huygens. We combined Irwin's and Huygens' data to obtain more reliable methane absorption coefficients for the temperatures in the atmospheres of the Jovian planets and Titan. This research was supported by NASA grants NAG5-12014 and NNX08AE74G.

Karkoschka, Erich; Tomasko, M. G.

2009-09-01

30

Near-millimeter refractive indices, absorption coefficients, and electrooptic coefficients in ferroelectric and other crystals  

Microsoft Academic Search

We have used a Michelson interferometer operating in the power mode to measure the refractive indices and absorption coefficients over the near-millimeter-wave (NMMW) spectral region of single-crystal bismuth germanium oxide, bismuth silicon oxide, titanium dioxide, lithium niobate, lithium tantalate, and strontium titanate. The NMMW value of the electrooptic coefficient r33 for dc fields in lithium niobate was also measured.

P. S. Brody; J. P. Sattler; G. J. Simonis

1983-01-01

31

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

NASA Astrophysics Data System (ADS)

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

Li, Xiaoqi; Jiang, Huabei

2013-02-01

32

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

PubMed

We present a study through extensive simulation that considers the impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data collected from media mimicking breast tissue. We found that while the impact of scattering heterogeneities/targets is modest on photoacoustic recovery of optical absorption coefficients, the impact of scattering contrast caused by adipose tissue, a layer of normal tissue along the boundary of the breast, is dramatic on reconstruction of optical absorption coefficients using photoacoustic data-up to 25.8% relative error in recovering the absorption coefficient is estimated in such cases. To overcome this problem, we propose a new method to enhance photoacoustic recovery of the optical absorption coefficient in heterogeneous media by considering inhomogeneous scattering coefficient distribution provided by diffuse optical tomography (DOT). Results from extensive simulations show that photoacoustic recovery of absorption coefficient maps can be improved considerably with a priori scattering information from DOT. PMID:23339968

Li, Xiaoqi; Jiang, Huabei

2013-01-23

33

A high absorption coefficient DL-MPP imitating owl skin  

NASA Astrophysics Data System (ADS)

This paper proposes a high absorption coefficient micro-perforated panel (MPP) imitating owl skin structure for acoustic noise reduction. Compared to the traditional micro-perforated panel, this device has two unique characteristics-simulating the owl skin structure, its radius of perforated apertures even can be as small as 55?, and its material is silicon and fabricated by micro-electrical mechanical system (MEMS) technology; So that its absorption coefficients of acoustic noise for normal incidence sound wave whose frequencies arrange from 1.5 kHz to 6.0 kHz are all above 0.8 which is the owl's hunts sensitivity frequency band. Double leaf MPP fabricated by MEMS technology is an absolutely bionic success in functional-imitation.

Guo, Lijun; Zhao, Zhan; Kong, Deyi; Wu, Shaohua; Du, Lidong; Fang, Zhen

2012-11-01

34

Sound absorption coefficient measurements by phase-conjugate ultrasonic waves  

NASA Astrophysics Data System (ADS)

Measurements of the sound absorption coefficient in test objects containing solid microparticles randomly distributed over the object volumes are carried out. Two methods are used for this purpose: the standard echo-pulse insert-substitution method and a modified method using phase conjugation of ultrasound. The test objects are made from gelatin, and the size of the particles introduced in it is chosen to allow measurements in both the long- and medium-wavelength scattering modes of the probing beam. It is shown that, in the first scattering mode, in which the presence of particles causes additional viscous and temperature losses, the two aforementioned methods give identical results. In the second scattering mode, in which the dominant mechanism of additional loss is elastic scattering, the use of phase conjugation allows an almost complete reconstruction of the scattered field and, hence, a more reliable upper estimate for the coefficient of ultrasonic absorption in the test objects.

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

2013-03-01

35

Photoelectric and diffusion component measurements of germanium interference absorption coefficient  

NASA Astrophysics Data System (ADS)

The photoelectric ?ph and diffusion ?ds components of the interference absorption coefficient ?i of germanium is measured using the synchrotron radiation of the Yerevan Electron Accelerator. There is a good agreement between the experimental and calculated values of ?ds, ? ph and?i for perfect Ge samples. Copper-decorated galium admixtures up to ~1018 at./cm3 change the absolute values of ?ph in the range of 9-11%, but do not influence the diffusion component of ?i.

Karabekov, I. P.; Egikian, D. L.; Mikaelian, R. A.; Bagdasarian, V. G.

1987-11-01

36

Measurements of carbon dioxide absorption coefficients with a CO laser  

Microsoft Academic Search

Pressure dependences of carbon dioxide absorption coefficients for several CO laser transitions from 1850 to 1920 cm-1 are measured. A comparison with the calculations (HITRAN-91) has been made. The calculated data for the Q-branch (1880.994 cm-1) of the (2020)I-0110 CO2 band are 20% lower than the measured ones. In the P-branch (1932.472 cm-1) of the (1110) -00 degree(s)0) CO2 band

Vladimir N. Aref'ev; Yu. I. Baranov; K. N. Visheratin

1994-01-01

37

Field testing of sound absorption coefficients in a classroom  

NASA Astrophysics Data System (ADS)

Formal procedures for determining the sound absorption coefficients of materials installed in the field do not exist. However, the U.S. Air Force requested such tests to prove that the sound-absorbing material used in classrooms at Beale AFB in Marysville, CA, met the specified NRC of 0.80. They permitted the use of two layers of 0.5-in. fiberboard or 1-in.-thick fiberglass panels to meet the specified NRC rating. Post-construction tests showed reverberation times longer than expected. Unrealistic sound-absorption coefficients for room finish materials had to be used with the Sabine equation to achieve agreement between the measured and predicted reverberation time. By employing the Fitzroy equation and generally published absorption coefficients for ceiling tile, carpet, and fiberboard, the model provided excellent agreement with the measured reverberation times. The NRC of the fiberboard was computed to be 0.35, agreeing with published data. Since this did not meet project specifications, the Fitzroy model was used to learn the type and quantity of material needed to meet design goals. Follow-up tests showed good agreement between the predicted and measured reverberation times with material added, and project specifications were met. Results are also compared with the requirements of ANSI 12.60.

Pettyjohn, Steve

2005-09-01

38

Water absorption of methacrylate soft lining materials.  

PubMed

The water absorption of soft methacrylate prosthetic materials is very high compared with rigid methacrylates and is not at an equilibrium value even after 6 yr. This very high and prolonged uptake can be explained qualitatively in terms of the presence of water soluble impurities which form sites for the formation of water droplets. These droplets grow until the osmotic and elastic forces balance; this mechanism can be accompanied by creep or even rupture under the osmotic pressure. Desorption on the other hand, is rapid and obeys diffusion laws, giving diffusion coefficients of 5-7 X 10(-8) cm2 s-1. PMID:2706307

Parker, S; Braden, M

1989-03-01

39

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

40

Measurement of the Absorption Coefficient of Semi-Transparent Media at High Temperatures.  

National Technical Information Service (NTIS)

The absorption coefficients of semi-transparent media control the magnitude of the radiation conduction contribution to the heat transfer in high temperature processes. An apparatus for measuring the absorption and extinction coefficients has been success...

Y. Shiraishi

1987-01-01

41

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...

42

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

Microsoft Academic Search

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

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

2006-01-01

43

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

Microsoft Academic Search

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

Pedro Andreo; David T Burns; Francesc Salvat

2012-01-01

44

From water clustering to osmotic coefficients.  

PubMed

Water activity is an important macroscopic property of aerosol particles and droplets in the atmosphere as well as aqueous solutions in many other fields of physical chemistry. This study focuses on relating water activity, described using osmotic coefficients, to the microscopic water structure in systems of atmospheric relevance, namely, aqueous solutions of each of the four electrolytes: NaCl, (NH(4))(2)SO(4), NH(4)Cl, and Na(2)SO(4). The osmotic coefficients of these compounds, as reported in literature based on thermodynamic measurements, decrease as a function of molality for dilute solutions and increase as a function of molality for concentrated solutions. At an intermediate molality, a minimum value of the osmotic coefficient is observed. We explain this behavior by describing osmotic coefficients as the product of two concentration-dependent effects: incomplete electrolyte dissociation and variations in the microphysical water structure. The degree of dissociation in electrolyte solutions can be obtained directly from literature or derived from reported pK values, and in this work the water structure is quantified using low-wavenumber Raman spectroscopy. We use the band at 180 cm(-1) in Raman spectra of aqueous electrolyte solutions, which has been assigned to the displacement of the central oxygen atom in a tetrahedral hydrogen bonding environment composed of five H(2)O units. The abundance of such translationally restricted water molecules is essential in describing the local microphysical structure of water, and the height of the band is used to estimate the amount of such translationally restricted water molecules in solution. We were able to qualitatively reproduce and explain literature values of osmotic coefficients for the four studied electrolytes. Our results indicate that the effect of electrolyte dissociation, which decreases as a function of molality, dominates in dilute solutions, whereas changes in water structure are more significant at higher concentrations. PMID:20945872

Frosch, Mia; Bilde, Merete; Nielsen, Ole F

2010-11-11

45

Oxygen absorption into moving water and tenside solutions  

Microsoft Academic Search

Oxygen absorption into water and waste water is an important process taking place with both natural and technical means, and a tool for a theoretical determination of the oxygen transfer coefficient, KL, is desirable.The objective of this investigation was to study the environment at and near the liquid side of a gas–liquid interface in order to present a model for

Tom Pedersen

2000-01-01

46

Optimization of optical absorption coefficient in asymmetric double rectangular quantum wells by PSO algorithm  

NASA Astrophysics Data System (ADS)

Optical absorption coefficient for asymmetric double rectangular quantum wells is optimized by the use of the particle swarm optimization (PSO) algorithm. By applying this method and numerical solution of Schrödinger equation, optimal quantum structure is determined for maximized absorption coefficient. Results show that the total absorption coefficient for this structure is 2.5365×105m-1 and its sensitivity is more than the changes of the first well width. Then the refractive index changes are investigated by using the density matrix method.

Keshavarz, A.; Zamani, N.

2013-05-01

47

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.

2011-09-01

48

Measurement of water absorption in human cornea with differential absorption optical coherence tomography  

NASA Astrophysics Data System (ADS)

OCT has emerged in recent years to a powerful technique to measure tissue properties. Recently, OCT has been enhanced by methods providing spectroscopic information. Since water is a major constituent of most tissues, the measurement of its concentration in tissue is important for tissue diagnostics. We present measurements of water absorption in human cornea in vitro with a differential absorption optical coherence tomography technique. This technique uses two OCT images recorded simultaneously with two different light sources, one centered within (1488nm) and one centered outside (1312nm) of a water absorption band. To study influences of scattering on the absorption images and on the calculated differential absorption coefficient, the cornea was measured and imaged under three different conditions: At first, the cornea was imaged in a hydrated condition, immediately after removal from the aqueous nutrient solution. Then it was dehydrated and imaged a second time, finally it was rehydrated, however, the water was replaced by Deuterium oxide, which shows negligible absorption in the used wavelength region, but otherwise has similar optical properties as water. The cornea containing H2O is well distinguishable from the cornea containing D2O with our method. For quantitative determination of absorption, we performed a linear regression analysis of logarithmic backscattered intensity versus imaging depth in the cornea for each wavelength. The difference of the slopes corresponds to the difference in the absorption coefficient. If the difference in the water absorption cross section is known, the water concentration in tissue can be calculated. The results are in good agreement with those expected theoretically.

Pircher, Michael; Götzinger, Erich; Leitgeb, Rainer; Fercher, Adolf F.; Hitzenberger, Christoph K.

2003-07-01

49

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

PubMed

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

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

2012-07-01

50

Water absorption of expanded polystyrene boards  

Microsoft Academic Search

The water absorption of expanded polystyrene boards was studied with the aim of developing a procedure for prediction of long-term absorption on the basis of short-term absorption data.The specifications of EN 12087 on test methods for determining long-term water absorption of expanded polystyrene by total immersion over a period of 28 days have been discussed and some disagreement between the

I. Y. Gnip; V. Kersulis; S. Vejelis; S. Vaitkus

2006-01-01

51

Octanol-Water Partition Coefficients by Capillary Electrophoresis.  

National Technical Information Service (NTIS)

We have investigated the use of capillary electrophoresis (CE) for the modeling of octanol-water partition coefficients. Reversed-phase liquid chromatography (RPLC) is likely the most used method for estimation of octanol-water partition coefficients, wit...

J. G. Dorsey

1997-01-01

52

Spectral absorption coefficients and imaginary parts of refractive indices of Saharan dust during SAMUM-1  

NASA Astrophysics Data System (ADS)

ABSTRACT During the SAMUM-1 experiment, absorption coefficients and imaginary parts of refractive indices of mineral dust particles were investigated in southern Morocco. Main absorbing constituents of airborne samples were identified to be iron oxide and soot. Spectral absorption coefficients were measured using a spectral optical absorption photometer (SOAP) in the wavelength range from 300 to 800 nm with a resolution of 50 nm. A new method that accounts for a loading-dependent correction of fibre filter based absorption photometers, was developed. The imaginary part of the refractive index was determined using Mie calculations from 350 to 800 nm. The spectral absorption coefficient allowed a separation between dust and soot absorption. A correlation analysis showed that the dust absorption coefficient is correlated (R2 up to 0.55) with the particle number concentration for particle diameters larger than 0.5 ?m, whereas the coefficient of determination R2 for smaller particles is below 0.1. Refractive indices were derived for both the total aerosol and a dust aerosol that was corrected for soot absorption. Average imaginary parts of refractive indices of the entire aerosol are 7.4 × 10-3, 3.4 × 10-3 and 2.0 × 10-3 at wavelengths of 450, 550 and 650 nm. After a correction for the soot absorption, imaginary parts of refractive indices are 5.1 × 10-3, 1.6 × 10-3 and 4.5 × 10-4.

Müller, T.; Schladitz, A.; Massling, A.; Kaaden, N.; Kandler, K.; Wiedensohler, A.

2009-02-01

53

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

54

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

55

Determining Scattering and Absorption Coefficients by Diffuse Illumination.  

National Technical Information Service (NTIS)

Opacity is a highly important use requirement of printing papers. Fundamental to the optical property of opacity are the light scattering and the absorptive powers of the paper. Two methods for measuring these optical properties of paper and pulp were eva...

F. A. Simmonds C. L. Coens

1967-01-01

56

Nonlinear photoacoustics for measuring the nonlinear optical absorption coefficient.  

PubMed

We report a novel photoacoustic Z-scan (PAZ-scan) technique that combines the advantages offered by the conventional Z-scan method and the sensitivity of the photoacoustic detection. The sample is scanned through the focused laser beam and the generated photoacoustic signal is recorded using a 10 MHz focused ultrasound transducer. Since the signal strength is directly proportional to the optical absorption, PAZ-scan displays nonlinear behavior depicting the nonlinear optical absorption of the material. Among many advantages, our experiments on mouse blood show that PAZ-scan can potentially be used as a standard technique to calibrate contrast agents used in theranostics in general and photoacoustics in particular. PMID:20588748

Yelleswarapu, Chandra S; Kothapalli, Sri-Rajasekhar

2010-04-26

57

Water permeability of plant cuticles: permeance, diffusion and partition coefficients  

Microsoft Academic Search

Using isolated cuticular membranes from ten woody and herbaceous plant species, permeance and diffusion coefficients for water were measured, and partition coefficients were calculated. The cuticular membranes of fruit had much higher permeance and diffusion coefficients than leaf cuticular membranes from either trees or herbs. Both diffusion and partition coefficients increased with increasing membrane thickness. Thin cuticles, therefore, tend to

Matthias Becker; Gerhard Kerstiens; Jörg Schönherr

1986-01-01

58

Determination of refractive index and absorption coefficient of iron- oxide-bearing slags  

NASA Astrophysics Data System (ADS)

The refractive index and absorption coefficient of amorphous Fe2O3-SiO2-CaO-Al2O3 slags have been determined at room temperature as functions of the basicity of [mass pct CaO]/[mass pct SiO2] and the Fe2O3 concentration. The refractive index has been measured by an ellipsometer at 546 nm, and the absorption coefficient has been determined from transmittance measured by a spectrophotometer in the wavelength range of 350 to 1000 nm. The refractive index increases with increasing basicity of [CaO]/[SiO2] and the Fe2O3 concentration. On the other hand, with decreasing basicity of [CaO]/[SiO2], the absorption coefficient is increased in the near-infrared region, and the absorption edge by the charge transfer band is shifted to a shorter wavelength. With increasing Fe2O3 concentration, the absorption coefficient is increased in the measured wavelength range, and the absorption edge by the charge transfer band is shifted to a longer wavelength. These dependences of refractive index and absorption coefficient on the basicity and the Fe2O3 concentration are discussed.

Susa, Masahiro; Li, Futao; Nagata, Kazuhiro

1992-06-01

59

Self-absorption correction for beta radioactivity measurements in water samples  

Microsoft Academic Search

Two methods were used to apply self-absorption corrections for the determination of beta radioactivity in water samples (either for an identified radionuclide or for monitoring trends). One method was performed by estimating the absorption coefficient by assuming an exponential behaviour of absorption using external absorbers, while the other method was performed by preparing empirical curves using standards of different mass.

Ll Pujol; J. A Suarez-Navarro

2004-01-01

60

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

61

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

62

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

Microsoft Academic Search

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

Angelo Farina; Anna Torelli

63

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

64

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

EPA Science Inventory

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

65

[Extracting THz absorption coefficient spectrum based on accurate determination of sample thickness].  

PubMed

Extracting absorption spectrum in THz band is one of the important aspects in THz applications. Sample's absorption coefficient has a complex nonlinear relationship with its thickness. However, as it is not convenient to measure the thickness directly, absorption spectrum is usually determined incorrectly. Based on the method proposed by Duvillaret which was used to precisely determine the thickness of LiNbO3, the approach to measuring the absorption coefficient spectra of glutamine and histidine in frequency range from 0.3 to 2.6 THz(1 THz = 10(12) Hz) was improved in this paper. In order to validate the correctness of this absorption spectrum, we designed a series of experiments to compare the linearity of absorption coefficient belonging to one kind amino acid in different concentrations. The results indicate that as agreed by Lambert-Beer's Law, absorption coefficient spectrum of amino acid from the improved algorithm performs better linearity with its concentration than that from the common algorithm, which can be the basis of quantitative analysis in further researches. PMID:22715781

Li, Zhi; Zhang, Zhao-hui; Zhao, Xiao-yan; Su, Hai-xia; Yan, Fang

2012-04-01

66

Implications of New Methane Absorption Coefficients on Uranus Vertical Structure Derived from Near-IR Spectra  

NASA Astrophysics Data System (ADS)

Using new methane absorption coefficients from Karkoschka and Tomasko (2009, submitted to Icarus, "Methane Absorption Coefficients for the Jovian Planets from Laboratory, Huygens, and HST Data"), we fit Uranus near-IR spectra previously analyzed in Sromovsky et al. (2006, Icarus 182, 577-593, Fink and Larson, 1979 J- and H-band), Sromovsky and Fry (2008, Icarus 193, 252-266, 2006 NIRC2 J- and H-band, 2006 SpeX) using Irwin et al. (2006, Icarus 181, 309-319) methane absorption coefficients. Because the new absorption coefficients usually result in higher opacities at the low temperatures seen in Uranus' upper troposphere, our previously derived cloud altitudes are expected to generally rise to higher altitudes. For example, using Lindal et al. (1987, JGR 92, 14987-15001) model D temperature and methane abundance profiles, we are better able to fit the J-band 43-deg. south bright band with the new coefficients (chi-square=205, vs. 315 for Irwin), with the pressure of the upper tropospheric cloud decreasing to 1.6 bars (from 2.4 bars using Irwin coefficients). Improvements in fitting H-band spectra from the same latitude are not as readily obtained. Derived upper tropospheric cloud pressures are very similar using the two absorption datasets (1.6-1.7 bars), but the character of the fits differs. New Karkoschka and Tomasko coefficients better fit some details in the 1.5-1.58 micron region, but Irwin fits the broad absorption band wing at 1.61-1.62 microns better, and the fit chi-square values are similar (K&T: 243, Irwin: 220). Results for a higher methane concentration (Lindal et al. model F) were similar. Whether the new coefficients will simply raise derived altitudes across the planet or will result in fundamental changes in structure is as yet unclear. This work was suported by NASA planetary astronomy and planetary atmospheres programs.

Fry, Patrick M.; Sromovsky, L. A.

2009-09-01

67

Water dimer absorption of visible light  

NASA Astrophysics Data System (ADS)

Laboratory measurements of water vapor absorption using cavity ring-down spectroscopy revealed a broad absorption at 405 nm with a quadratic dependence on water monomer concentration, a similar absorption with a linear component at 532 nm, and only linear absorption at 570 nm in the vicinity of water monomer peaks. D2O absorption is weaker and linear at 405 nm. Van't Hoff plots constructed at 405.26 nm suggest that for dimerization, Keq=0.056±0.02 atm-1, ?H°301 K=-16.6±2 kJ mol-1 and ?S°301 K=-80±10 J mol-1 K-1. This transition peaks at 409.5 nm, could be attributed to the 8th overtone of water dimer and the 532 nm absorption to the 6th overtone. It is possible that some lower overtones previously searched for are less enhanced. These absorptions could increase water vapor feed back calculations leading to higher global temperature projections with currently projected greenhouse gas levels or greater cooling from greenhouse gas reductions.

Hargrove, J.

2007-07-01

68

Optical absorption of pure water in the blue and ultraviolet  

NASA Astrophysics Data System (ADS)

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

Lu, Zheng

69

Compressional Viscosity and Sound Absorption in Water at Different Temperatures  

Microsoft Academic Search

The temperature dependence of the coefficient of absorption (2alphanu-2) of ultrasonic waves in water was measured from 0°C to 33°C. Values range from 137×10-17 at 0°C to 40×10-17 at 33°C. In particular at 4°C where the sound propagation is isothermal the value 101×10-17 is found, and is to be compared with a shear viscosity contribution of 30×10-17. Therefore the excess

Francis E. Fox; George D. Rock

1946-01-01

70

Si quantum dots with a high absorption coefficient: Analysis based on both intensive and extensive variables  

NASA Astrophysics Data System (ADS)

Silicon quantum dots (Si-QDs) were produced by pulsed laser ablation in liquid. By measuring the absorption spectra and the concentration of the Si-QD solution, two extinction coefficients were obtained from UV to near IR region: the atomic molar extinction coefficient and the quantum dot molar extinction coefficient. The magnitude of the atomic molar extinction coefficient of the Si-QDs was found to be up to 30 and 270 times those of crystalline and amorphous Si, respectively, and up to 740 times that of previously fabricated Si-QDs. The Si-QDs remained stably dispersed in hydrocarbon and alcohol solvents for over 10 months.

Kitasako, Takumi; Saitow, Ken-ichi

2013-10-01

71

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

72

Characterizing the Chlorophyll-a Specific Absorption Coefficient of Phytoplankton Measured in the Gulf of Maine in Varying Oceanic Provinces  

NASA Astrophysics Data System (ADS)

Chlorophyll-a specific absorption (aph*) is a parameter used in bio-optical and primary production models and its coefficients are usually assumed to be constant. However, it has been documented in previous studies that these coefficients vary significantly due to pigmentation and "the package effect" which are a function of the taxonomic composition and the physiological state of the algal population. As part of the Coastal Ocean Observing Center (COOC) at the University of New Hampshire, HPLC pigments and phytoplankton absorption measurements were taken from water samples collected within the Gulf of Maine from 2004-2006. These data were then partitioned spatially, temporally, seasonally, and by other classification criteria. Spectral aph* means were generated for all partitions within each classification method. The results were used to parameterize province-specific bio-optical models for a regional algorithm. The separation of aph* means into different classes captured the effects of taxonomy and the package effect by reducing aph* variability.

Dowell, M.

2006-12-01

73

Probable X-Ray Mass Absorption Coefficients for Wave-Lengths Shorter Than the K Critical Absorption Wave-Length  

Microsoft Academic Search

Absorption coefficients of all elements may be calculated, from short wave-lengths up to the K critical absorption wave-length by the expression: ??&rgr;=??3Z2(2Z?A)???4Z5(2Z?A)+?eN0(Z?A). This formula holds for all elements when suitable values for ? and ? are chosen. Factors ? and ? are related to the atomic number, Z, by the expressions ?=(aZ2+bZ?c), and ?=(dZ2?eZ+f). Different values of the constants a,

John A. Victoreen

1943-01-01

74

A numerical study of a method for measuring the effective in situ sound absorption coefficient.  

PubMed

The accuracy of a method [Wijnant et al., Proc. of ISMA 31, Leuven, Belgium (2010), Vol. 31] for measurement of the effective area-averaged in situ sound absorption coefficient is investigated. Based on a local plane wave assumption, this method can be applied to sound fields for which a model is not available. Investigations were carried out by means of finite element simulations for a typical case. The results show that the method is a promising method for determining the effective area-averaged in situ sound absorption coefficient in complex sound fields. PMID:22979838

Kuipers, Erwin R; Wijnant, Ysbrand H; de Boer, André

2012-09-01

75

Infrared absorption coefficient of molten LiF and Li2S  

NASA Astrophysics Data System (ADS)

A method based on the 'submerged mirror' technique to measure absorption coefficients of liquids at elevated temperatures is presented. Modulated radiation reflected off the sample was collected by a HgCdTe infrared detector and the subsequent signals were processed by an FTIR spectrometer. Apparent reflectivities of two samples of different thicknesses and the first surface reflectivity were measured, and the absorption coefficients were calculated. Absorption coefficients in the range 0.5-11/cm were measured using samples of thicknesses 1-2 mm. The absorption coefficients of molten LiF, Li2S, and the (6LiF + Li2S) eutectic mixture were measured for wavelengths between 1.5 micron and their infrared absorption edge. Measurements were carried out for a range of temperatures between the respective melting points and 1400 C. The measured data for LiF at 900 C are in good agreement with published data. An uncertainty analysis shows the error associated with these measurements to be within 20 percent.

Gupta, Sreenath B.; Modest, Michael F.

1993-07-01

76

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

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

77

X-ray absorption coefficient of iodine in the K edge region  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy of iodine vapour is used for absolute determination of the absorption coefficient of iodine within a region of 4.3 keV around the K edge. The comparison with data in available compilations is given, together with the compressed form of the Victoreen asymptotics below and above the edge. The deviation from the asymptotics due to multielectron excitations and virtual processes immediately above the edge is discussed.

Padežnik Gomilšek, J.; Ar?on, I.; de Panfilis, S.; Kodre, A.

2008-01-01

78

Measuring Water Vapor with Differential Absorption Lidar  

NASA Astrophysics Data System (ADS)

Despite the need for global measurements of water vapor profiles with low bias and high vertical resolution there is currently no operational remote sensing system that would deliver such data. A possible solution to this problem is offered by the differential absorption lidar (DIAL) approach. The basic principle of operation will be described and some background on atmospheric light absorption by water vapor will be given. DLR's airborne water vapor DIAL system WALES represents the currently most advanced system worldwide using a multiwavelength technique to cover the troposphere and lower stratosphere simultaneously. A few examples of measurements made with this system will illustrate the power of this active remote sensing method.

Wirth, Martin

79

Experimental study and parameterization of gas absorption by water drops  

SciTech Connect

Mass transfer between liquid drops and a continuous gas phase occurs in a large number of industrial processes and many engineering disciplines such as chemical and nuclear engineering, atmospheric sciences, environmental engineering, and so on. Liquid-phase mass-transfer coefficients are determined for the absorption of sulfur dioxide by water drops larger than 1.1 mm in dia. A local model based on the large eddy interfacial model proposed for Fortescue and Pearson (1967) is obtained by the characteristic interfacial scaling. In particular, the agitation process of the liquid phase in the interfacial region is characterized by the interfacial liquid friction velocity. Experiments of sulfur dioxide absorption and desorption from large individually free-falling water drops are also carried out in a 5-m rain shaft under various environmental conditions. These experimental results agree well with those from the local model characterizing the interfacial process in water drops greater than 1.1 mm in dia.

Amokrane, H.; Saboni, A.; Caussade, B. (CNRS, Toulouse (France). Inst. de Mecanique des Fluides)

1994-12-01

80

Relationships between octanol-water partition coefficient and aqueous solubility  

Microsoft Academic Search

The thermodynamic relationship between octanol-water partition coefficient and aqueous solubility is discussed in the light of recently measured data for highly hydrophobic chemicals. Experimental data indicate that the presence of dissolved octanol in water has little effect on the solubility of chemicals in water and that the presence of dissolved water in octanol has little effect on the solubility of

Michele M. Miller; S. P. Waslk; Guo Lan Huang; Wan Ying Shiu; Donald Mackay

1985-01-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

82

Size dependence of molar absorption coefficients of CdSe semiconductor quantum rods.  

PubMed

Fundamental properties: The molar absorption coefficients of CdSe quantum rods are determined experimentally as a function of their dimensions (see figure). Far above the band gap a simple dependence on volume is seen. The behavior at the band gap manifests a concentration of oscillator strength with decreased diameter in agreement with strong quantum confinement behavior. PMID:19347917

Shaviv, Ehud; Salant, Asaf; Banin, Uri

2009-05-11

83

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

84

Improvement in quantifying optical absorption coefficients based on continuous wavelet-transform by correcting distortions in temporal photoacoustic waveforms  

NASA Astrophysics Data System (ADS)

Quantification of the optical absorption coefficients of optical absorbers using photoacoustic (PA) pressure waves with broadband frequency was reported. We proposed to use continuous wavelet-transform (CWT) to obtain time-resolved frequency spectra of PA signals and demonstrated the relationship between optical absorption coefficients of optical absorbers and CWT of PA signals. However, the optical absorption coefficients of the optical absorbers were not quantified. Thus, in this research, we quantified optical absorption coefficients of optical absorbers by using the calibration curve which relates the optical absorption coefficients of optical absorbers and CWTs of PA signals. The calibration curve is derived from the simulation. However, due to the frequency response of the acoustic sensor, the simulated PA pressure waves differed from the measured PA signals. Thus, we measured the frequency response of the acoustic sensor. By convolving the frequency response of the acoustic sensor to the simulated pressure waves, we simulated the PA signals which were obtained by measuring the PA pressure wave using the acoustic sensor. The calibration curve derived from the simulated PA signal enabled to quantify optical absorption coefficients of optical absorbers. We verified the method by quantifying optical absorption coefficients of blood vessel phantoms which is tubes filled with diluted inks with optical absorption coefficients from 10 to 40 cm-1. As results, the simulated PA signals demonstrated close similarity with the measured PA signals, and the optical absorption coefficients of the blood vessel phantoms were quantified with root mean square error of 2.42 cm-1.

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

2013-03-01

85

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

86

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

PubMed

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

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

2012-06-01

87

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

PubMed Central

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

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

2012-01-01

88

Correlation of octanol/water solubility ratios and partition coefficients  

SciTech Connect

The partition coefficient between octanol and water in an important physicochemical parameter for characterizing the lipophilicity or hydrophobicity of a compound and it is used in many fields, especially in the environmental and pharmaceutical sciences. The octanol/water solubility ratio (S{sub o}/S{sub W}) was found to be highly correlated with the octanol/water partition coefficient (K{sub ow}) of 82 pharmaceutically and environmentally relevant compounds. The solubility ratio gives comparable estimates to that of the group contribution (log P(calcd)) method for estimating the partition coefficient of the compounds used in this study.

Pinsuwan, S.; Li, A.; Yalkowsky, S.H. [Univ. of Arizona, Tucson, AZ (United States). Dept. of Pharmaceutical Sciences

1995-05-01

89

Optical properties of the adaxial and abaxial faces of leaves. Chlorophyll fluorescence, absorption and scattering coefficients.  

PubMed

Emission fluorescence spectra were obtained for the adaxial and abaxial faces of dicotyledonous (Ficus benjamina L., Ficus elastica, Gardenia jasminoides and Hedera helix) and monocotyledonous leaves (Gladiolus spp. and Dracaena cincta bicolor). After correction by light-re-absorption processes, using a previously published physical model, the adaxial faces of dicotyledons showed a fluorescence ratio Fred/Ffar-red rather lower than the respective values for the abaxial faces. Monocotyledons and shade-adapted-plants showed similar values for the corrected fluorescence ratio for both faces. Even when differences in experimental fluorescence emission from adaxial and abaxial leaves in dicotyledons are mostly due to light re-absorption processes, the residual dissimilarity found after application of the correction model would point to the fact that fluorescence re-absorption is not the only responsible for the observed disparity. It was concluded that light re-absorption processes does not account entirely for the differences in the experimental emission spectra between adaxial and abaxial leaves. Differences that remains still present after correction might be interpreted in terms of a different photosystem ratio (PSII/PSI). Experiments at low temperature sustained this hypothesis. In dicotyledons, light reflectance for adaxial leaves was found to be lower than for the abaxial ones. It was mainly due to an increase in the scattering coefficient for the lower leaf-side. The absorption coefficient values were slightly higher for the upper leaf-side. During senescence of Ficus benjamina leaves, the scattering coefficient increased for both the upper and lower leaf-sides. With senescence time the absorption coefficient spectra broadened while the corrected fluorescence ratio (Fred/Ffar-red) decreased for both faces. The results pointed to a preferential destruction of photosystem II relative to photosystem I during senescence. PMID:17668118

Cordón, Gabriela B; Lagorio, María G

2007-06-20

90

Natural variability of phytoplanktonic absorption in oceanic waters: Influence of the size structure of algal populations  

Microsoft Academic Search

The spectral absorption coefficients of phytoplankton in oceanic waters were previously shown to vary with chlorophyll a concentration according to nonlinear relationships with a great deal of noise. We analyzed this biological noise on a data set of 596 simultaneous absorption and high-pressure liquid chromatography (HPLC) pigment measurements acquired within the surface layer (first optical depth) from various regions of

Annick Bricaud; Hervé Claustre; Joséphine Ras; Kadija Oubelkheir

2004-01-01

91

Water diffusion coefficients during copper electropolishing  

Microsoft Academic Search

Cu electropolishing was studied using a rotating disc electrode in a variety of phosphoric acid-based electrolytes, including several with ethanol and other species added as diluents. Diluents allow a wider range of water concentrations and electrolyte viscosities to be accessed and also reduce the removal rate during Cu electropolishing, simplifying possible application to damascene processing. Transient and steady state currents

Bing Du; Ian Ivar suni

2004-01-01

92

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

PubMed

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

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

2012-03-13

93

Prediction of 1-octanol–water partition coefficient and infinite dilution activity coefficient in water from the PR + COSMOSAC model  

Microsoft Academic Search

The Peng–Robinson equation of state (PR EOS) is used for the prediction of 1-octanol–water partition coefficients (KOW) and infinite dilution activity coefficients (??). Unlike the conventional approach where the EOS parameters must be determined from the critical properties and acentric factor of each chemical species in addition to using some mixing rule to account for composition dependence, these parameters are

Chieh-Ming Hsieh; Shiang-Tai Lin

2009-01-01

94

Direct absorption spectroscopy of water clusters  

SciTech Connect

Water plays a major role in solar absorption in the atmosphere in the mid- and near-infrared, particularly at altitudes of less than 15 km. The earth's atmosphere also acts as an insulator by trapping up-welling radiation. This phenomenon is known as the greenhouse effect, and water vapor is a major contributor through its mid- and far-infrared absorption. Fourier Transform infrared spectrometry has been used to study the vibrational spectroscopy of water clusters prepared in a supersonic expansion. The clusters are assigned as being composed of 10--100 waters based on consideration of the free OH and bound OH vibrations and the experimental conditions used. Four vibrational features were observed simultaneously including the bend, free OH stretch, bound OH stretch, and an unresolved group of intermolecular vibrations. No absorption features were observed between 4,000 and 8,000 cm{sup {minus}1}. This is the first observation of the bending vibration for any size gas-phase water cluster.

Goss, L.M.; Sharpe, S.W.; Blake, T.A.; Vaida, V.; Brault, J.W.

1999-10-28

95

Quantification of optical absorption coefficient from acoustic spectra in the optical diffusive regime using photoacoustic microscopy  

NASA Astrophysics Data System (ADS)

Photoacoustic (PA) tomography (PAT) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Multi-wavelength PAT can noninvasively monitor hemoglobin oxygen saturation (sO2) with high sensitivity and fine spatial resolution. However, accurate quantification in PAT requires knowledge of the optical fluence distribution, acoustic wave attenuation, and detection system bandwidth. We propose a method to circumvent this requirement using acoustic spectra of PA signals acquired at two optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560 and 575 nm were quantified with errors of ><5%.

Guo, Zijian; Favazza, Christopher; Wang, Lihong V.

2012-02-01

96

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

NASA Astrophysics Data System (ADS)

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

Fujita, Isamu; Hihara, Eiji

97

Spectral absorption coefficient measured in situ in the North Sea with a marine radiometric spectrometer system  

Microsoft Academic Search

A submersible marine radiometric spectrometer system, capable of simultaneous measurements of the in situ spectral and angular properties of the underwater oceanic light field, is used to determine spectral inherent optical properties of marine waters. The inversion methods used to convert the sampled light field measurements into estimates of spectral absorption are presented and sample results for three water types

Eon O'Mongain; Daniel Buckton; Stuart Green; Martina Bree; Karl Moore; Roland Doerffer; Sean Danaher; Hans Hakvoort; John Kennedy; Jürgen Fischer; Frank Fell; Dimitris Papantoniou; Martin McGarrigle

1997-01-01

98

Retrieval of gelbstoff absorption coefficient in pearl river estuary using remotely-sensed ocean color data  

Microsoft Academic Search

Gelbstoff is the main absorber in natural waters of UV and visible light, and has an increasing absorption with decreasing wavelength in the range between 700 and 350 nm. Gelbstoff is often an important source of interference in the determination of plant pigments (e.g., Chlorophyll a) in coastal waters using remotely- sensed ocean color data. The existence of gelbstoff will

Chuqun Chen; Ping Shi; Haigan Zhan; Eric P. Achterberg; Samantha J Lavender; Magnus Larson; L. Jeonsson

2005-01-01

99

The interband light absorption coefficient in the weak disorder regime: an asymptotically exactly solvable model  

Microsoft Academic Search

We consider the interband light absorption coefficient (ILAC) for a d-dimensional discrete disordered system, whose Hamiltonian consist of a translation invariant part (d-dimensional discrete Laplacian) and an off-diagonal random part. Assuming that the range R of the latter is large and that its magnitude is of the order R-d\\/2 we find that R= infinity limit of the ILAC. We discuss

B A Khoruzhenko; W Kirsch; L A Pastur

1994-01-01

100

Water absorption in horizontal corrugated boards under water sprays  

Microsoft Academic Search

Experiments were performed to determine the water absorption propensity of four different corrugated boards oriented horizontally and exposed to vertical water sprays from above. The corrugated samples used in the experiments were taken from cartons and partition boards from the FM Global Standard Plastic Commodity and from the inner and outer cartons of the FM Global Class II Commodity. These

T. M. Jayaweera; H.-Z. Yu

2006-01-01

101

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

NASA Astrophysics Data System (ADS)

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

Karkoschka, Erich; Tomasko, Martin G.

2010-02-01

102

Absorption coefficient of intersubband transition at 1.55 µm in (CdS\\/ZnSe)\\/BeTe quantum wells  

Microsoft Academic Search

In this paper, the intersubband optical absorption coefficient is calculated in a ZnSe\\/CdS\\/ZnSe quantum well (QW) surrounded by BeTe barriers. First, the one-dimensional Poisson and Schrödinger equations have been solved self-consistently, and then the intersubband optical absorption between the lowest two levels has been theoretically studied under an external electric field. Simulated results including eigenvalues, absorption coefficient and electroabsorption properties

N. Sfina; S. Abdi-Ben Nasrallah; S. Mnasri; M. Said

2009-01-01

103

On cloud modelling and the mass accommodation coefficient of water  

NASA Astrophysics Data System (ADS)

The mass accommodation coefficient of water is a quantity for which different experimental techniques have yielded conflicting values in the range 0.04-1. From the viewpoint of cloud modelling, this is an unfortunate situation, since the value of the mass accommodation coefficient affects the model results, e.g. the number concentration of activated cloud droplets. In this paper we argue that a mass accommodation coefficient of unity should be used in cloud modelling, since this value has been obtained in experimental studies of water droplet growth rates, a quantity which is explicitly described in cloud models. In contrast, mass accommodation coefficient values below unity have been derived from experimental results which are analyzed with different theoretical expressions than those included in cloud models.

Laaksonen, A.; Vesala, T.; Kulmala, M.; Winkler, P. M.; Wagner, P. E.

2004-11-01

104

Americium speciation and distribution coefficients in a granitic ground water  

Microsoft Academic Search

The possible importance of pH-dependent speciation in determining the distribution coefficient of americium in a granitic ground water is discussed. The authors obtained experimental distribution coefficients for americium. The authors used the geochemical code PHREEQE to calculate the amount present of americium complexes with hydroxides and carbonates over a range of pH, using formation constants taken from the literature and

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

1986-01-01

105

Diffusion coefficient and shear viscosity of rigid water models  

Microsoft Academic Search

We report the diffusion coefficient and viscosity of popular rigid water models: two non-polarizable ones (SPC\\/E with three sites, and TIP4P\\/2005 with four sites) and a polarizable one (Dang–Chang, four sites). We exploit the dependence of the diffusion coefficient on the system size (Yeh and Hummer 2004 J. Phys. Chem. B 108 15873) to obtain the size-independent value. This also

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

2012-01-01

106

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

107

Optical band gap studies and estimation of two photon absorption coefficient in alkali bismuth borate glasses  

NASA Astrophysics Data System (ADS)

The optical absorption spectra of the glasses with composition xBi(2)O(3) . (30 - x)R2O . 70B(2)O(3) (R=Li, Na, K) and xBi(2)O(3) . (70 - x)B2O3 . 30Li(2)O (0 less than or equal to x less than or equal to 20) have been recorded in the wavelength range 350-650 nm. The glass samples were prepared by the normal melt-quench technique. The fundamental absorption edge for all the series of glasses is analyzed using the theory of Davis and Mott. The position of absorption edges and the values of optical band gap are dependent on the mol% of Bi2O3. The absorption in these glasses is associated with indirect transitions. The values of Urbach's energy and band tailing parameters are reported. The two photon absorption coefficient,, in these glasses has also been estimated from the optical band gap and its value ranges from 1.3 to 11.6 cm/GW. The relationship between beta and glass composition has also been discussed in terms of the electronic structure of the glass system.

Agarwal, A.; Seth, V. P.; Sanghi, S.; Gahlot, P.; Goyal, D. R.

2003-11-01

108

Absorption  

NSDL National Science Digital Library

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

Katie Hale (CSUF;)

2002-09-26

109

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

SciTech Connect

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 {mu}m, the weaker of the two absorptions, is delayed in time by several microseconds with respect to ablation at 3.47 {mu}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. Jr. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Bubb, D. M. [Department of Physics, Rutgers University-Camden, Camden, New Jersey 08102 (United States)

2009-01-15

110

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

PubMed

I use Monte Carlo simulations and phantom measurements to characterize a probe with adjacent optical fibres for diffuse reflectance spectroscopy during stereotactic surgery in the brain. Simulations and measurements have been fitted to a modified Beer-Lambert model for light transport in order to be able to quantify chromophore content based on clinically measured spectra in brain tissue. It was found that it is important to take the impact of the light absorption into account when calculating the apparent optical path length, lp, for the photons in order to get good estimates of the absorption coefficient, ?a. The optical path length was found to be well fitted to the equation lp=a+b ln(Is)+c ln(?a)+d ln(Is)ln(?a), where Is is the reflected light intensity for scattering alone (i.e., zero absorption). Although coefficients a-d calculated in this study are specific to the probe used here, the general form of the equation should be applicable to similar probes. PMID:21054121

Johansson, Johannes D

111

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

112

Opto-acoustic measurement of the local light absorption coefficient in turbid media: 2. On the possibility of light absorption coefficient measurement in a turbid medium from the amplitude of the opto-acoustic signal  

SciTech Connect

The second part of this work describes the experimental technique of measuring the local light absorption in turbid media. The technique is based on the measurement of the amplitude of an opto-acoustic (OA) signal excited in a turbid medium under the condition of one-sided access to the object under study. An OA transducer is developed to perform the proposed measurement procedure. Experiments are conducted for the turbid media with different optical properties (light absorption and reduced scattering coefficients) and for different diameters of the incident laser beam. It is found that the laser beam diameter can be chosen so that the dependences of the measured OA signal amplitude on the light absorption coefficient coincide upon varying the reduced scattering coefficient by more than twice. The obtained numerical and experimental results demonstrate that the OA method is applicable for measuring the local light absorption coefficient in turbid media, for example, in biological tissues. (measurement of parametrs of laser radiation)

Pelivanov, Ivan M; Barskaya, M I; Podymova, N B; Khokhlova, Tanya D; Karabutov, Aleksander A [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation)

2009-09-30

113

Diffusion coefficient and shear viscosity of rigid water models.  

PubMed

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

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

2012-06-27

114

Nonlinear refractive index and three-photon absorption coefficient of Poly(9,9-dioctylfluorence) (PFO)  

NASA Astrophysics Data System (ADS)

We report on the nonlinear optical Kerr effect and third harmonic generation (THG) arising from &(3)circ; of Poly(9,9- dioctylfluorence) (PFO), which is an emerging organic ?- conjugated polymer from the perspective of diverse optoelectronic applications. The measured nonlinear refractive index, obtained with closed-aperture Z-scan, is n2= (2.04 ±0.10)x10-12 esu at ?= 1540 nm. Open- aperture Z-scan yields the three-photon absorption coefficient of ?= (1.88 ±0.26) x10-3 cm^3/GW^2 at ?= 1064 nm, arising from &(5)circ; response. The observed three-photon absorption also strongly depends on the excitation wavelength. The wavelength-dependent THG indicates that this semiconducting polymer can be a potentially useful polymer system for nonlinear-optics applications involving high-order optical processes in the mid-IR range.

Mani, Shahin; Jang, Joon; Ketterson, John; Lovera, Pierre; Redmond, Gareth

2010-03-01

115

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

NASA Astrophysics Data System (ADS)

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

Courtin, Regis

1988-08-01

116

Seasonal variability of light absorption properties and water optical constituents in Hudson Bay, Canada  

NASA Astrophysics Data System (ADS)

Previous studies have shown that the properties of optically significant water constituents (phytoplankton, suspended matter, and colored dissolved organic matter (CDOM)) in Hudson Bay are different from other Arctic regions. A new bio-optical data set collected in summer 2010 shows that this region also presents seasonal variability of the light absorption coefficients by the different constituents, with a higher relative proportion of CDOM absorption in summer than in the fall as a result of decreased phytoplankton absorption in summer. The slope of the exponential function describing nonalgal particles and CDOM spectral absorption shows little variability between fall and summer. Seasonal variability of light absorption coefficients and water optical constituents is more pronounced near the coast, while less variability is observed in the central part of the bay. Very low summertime chlorophyll-specific absorption coefficients by phytoplankton, among the lowest reported in the literature, are attributed to the high proportion of large size phytoplankton (microphytoplankton) and important packaging effect. There is also a smaller contribution of accessory pigments to total pigments in the summer than in the fall, resulting in a lower blue-to-red phytoplankton absorption ratio. These results emphasize that it is necessary to take into account the seasonal variability of light absorption properties in bio-optical models for further remote sensing applications in Hudson Bay.

Xi, Hongyan; Larouche, Pierre; Tang, Shilin; Michel, Christine

2013-06-01

117

Partition Coefficients for Metals in Surface Water, Soil, and Waste.  

National Technical Information Service (NTIS)

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 Prote...

J. D. Allison T. L. Allison

2005-01-01

118

Octanol-Water Partition Coefficients of Simple Organic Compounds  

Microsoft Academic Search

Octanol-water partition coefficients (log P) for 611 simple organic compounds representing all principal classes have been retrieved from the literature. Available experimental details of measurement are documented from original articles. Pertinent thermodynamic relations are presented, with a discussion of direct and indirect methods of measurement. Reported log P data for each compound have been evaluated according to stated criteria, and

James Sangster

1989-01-01

119

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

120

Absorption of Solar Radiation by Water Vapor in the Atmosphere  

Microsoft Academic Search

Absorption of solar radiation by water vapor in the atmosphere has been studied, with use of Fowle's observed results and application of Elsasser's transmission function. The results are compared with those of other workers. Mügge-Möller's absorption curve and Karandikar's are discussed. As a result of calculations, an absorption chart is obtained from which both the absorption of solar radiation by

Giichi Yamamoto; Gaishi Onishi

1952-01-01

121

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

122

Detectability of absorption and reduced scattering coefficients in frequency-domain measurements using a realistic head phantom.  

PubMed

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

Zhang, Xiaofeng; Webb, Andrew

2012-12-24

123

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

PubMed Central

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

Zhang, Xiaofeng; Webb, Andrew

2013-01-01

124

An empirical algorithm for light absorption by ocean water based on color  

NASA Astrophysics Data System (ADS)

Empirical algorithms for the total absorption coefficient and absorption coefficient by pigments for surface waters at 440 nm were developed by applying a quadratic formula that combines two spectral ratios of remote-sensing reflectance. For total absorption coefficients ranging from 0.02 to 2.0 m-1, a goodness of fit was achieved between the measured and modeled data with a root-mean-square difference between the measured and modeled values for logl0 scale (RMSDlog10) of 0.062 (15.3% for linear scale, number of samples N = 63), while RMSDlog10 is 0.111 (29.1% for linear scale, N = 126) for pigment absorption (ranging from 0.01 to 1.0 m-1). As alternatives to pigment concentration algorithms, the absorption algorithms developed can be applied to the coastal zone color scanner and sea-viewing wide-field-of-view sensor data to derive inherent optical properties of the ocean. For the same data sets, we also directly related the chlorophyll a concentrations to the spectral ratios and obtained an RMSDlog10 value of 0.218 (65.2% for linear scale, N = 120) for concentrations ranging from 0.06 to 50.0 mg m-3. These results indicate that it is more accurate to estimate the absorption coefficients than the pigment concentrations from remotely sensed data. This is likely due to the fact that for the broad range of waters studied the pigment-specific absorption coefficient at 440 nm ranged from 0.02 to 0.2 m2 (mg chl)-1. As an indirect test of the algorithms developed, the chlorophyll a concentration algorithm is applied to an independent global data set and an RMSDlog10 of 0.191 (55.2% for linear scale, N = 919) is obtained. There is no independent global absorption data set available as yet to test the absorption algorithms.

Lee, Z. P.; Carder, K. L.; Steward, R. G.; Peacock, T. G.; Davis, C. O.; Patch, J. S.

1998-11-01

125

Diaphragm cell determination of the interdiffusion coefficient for succinonitrile + water  

SciTech Connect

Using diaphragm cells, we have measured the interdiffusion coefficient for succinonitrile+water in the one-phase liquid region at a series of temperatures ranging form 25 to 60{degrees}C and compositions ranging from 34.5 to 96 mol% water. The diffusion coefficient was found to be a function of both temperature and concentration, varying from 1.66x10{sup -6} to 16.6x10{sup -6} to 16.6x10{sup -6} cm{sup 2} {center_dot} s{sup -1}. Critical slowing down of diffusion was readily detected at 60{degrees}C (critical temperature, 56.17{degrees}C) over a broad range of composition on either side of the critical composition (82.7 mol% water).

Cain, J.B. [Univ. of North Carolina, Chapel Hill, NC (United States); Clunie, J.C.; Baird, J.K. [Univ. of Alabama, Huntsville, AL (United States)

1995-09-01

126

Mass absorption coefficient of tungsten for 1600-2100 eV  

NASA Astrophysics Data System (ADS)

The transmission of soft x rays with photon energies from 1606 eV to 2106 eV was measured for tungsten using thin-film samples and a synchrotron source. This region includes the MIV and MV edges. The two tungsten films had thicknesses of 107.7+/-10 nm and 51.5+/-10 nm the intensity of the transmitted x rays was measured with a silicon photodiode. The values for the mass absorption coefficient reported here were determined from the ratios of the transmission through the two samples, i.e., through a net 56.2+/-14 nm of tungsten, and some additional constant factors. The MV,IV edges have widths (10%-90% after background subtraction) of 33+/-5 eV and 28+/-5 eV, respectively, compared to zero width in all x-ray tables based on atomic form factors and to 41 eV and 44 eV within a real-space multiple-scattering theory. The measurements are relevant to microspectroscopy and microtomography of integrated circuit interconnects and may be applicable to accurate measurement of the mass absorption coefficients of similar dense elements.

Levine, Zachary H.; Grantham, Steven; McNulty, Ian

2002-02-01

127

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

PubMed

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

Seltzer, S M

1993-11-01

128

High absorption-coefficient and stable a-Si for high-efficiency solar cells  

NASA Astrophysics Data System (ADS)

A total area conversion efficiency of 10.2 percent has been obtained for a 100-sq cm a-Si solar cell. To further improve efficiency, a novel approach to preparing a-Si:H at a high substrate temperature (Ts) with low impurity contamination has been proposed. High-quality, stable a-Si with a high absorption coefficient and low Si-H2 bond density has been obtained by this method. The collection efficiency in the long wavelength region has been markedly increased with an a-Si solar cell using a high-Ts i-layer. Problems due to high-Ts deposition have been studied from the viewpoint of its application to solar cells. A novel cell structure with a flexible buffer is proposed to overcome these problems. A highly conductive p-type a-Si(1-x)C(x) (x about 0.55) alloy with a low absorption coefficient and high stability against thermal annealing has been developed using the controlled plasma magnetron method. This newly developed p-layer has been found to be well-suited to high-Ts a-Si solar cells.

Nakano, S.; Okamoto, S.; Takahama, T.; Nishikuni, M.; Ninomiya, K.

129

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.

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

2011-01-01

130

Absorption and scattering coefficient dependence of laser-Doppler flowmetry models for large tissue volumes  

NASA Astrophysics Data System (ADS)

Based on quasi-elastic scattering theory (and random walk on a lattice approach), a model of laser-Doppler flowmetry (LDF) has been derived which can be applied to measurements in large tissue volumes (e.g. when the interoptode distance is >30 mm). The model holds for a semi-infinite medium and takes into account the transport-corrected scattering coefficient and the absorption coefficient of the tissue, and the scattering coefficient of the red blood cells. The model holds for anisotropic scattering and for multiple scattering of the photons by the moving scatterers of finite size. In particular, it has also been possible to take into account the simultaneous presence of both Brownian and pure translational movements. An analytical and simplified version of the model has also been derived and its validity investigated, for the case of measurements in human skeletal muscle tissue. It is shown that at large optode spacing it is possible to use the simplified model, taking into account only a 'mean' light pathlength, to predict the blood flow related parameters. It is also demonstrated that the 'classical' blood volume parameter, derived from LDF instruments, may not represent the actual blood volume variations when the investigated tissue volume is large. The simplified model does not need knowledge of the tissue optical parameters and thus should allow the development of very simple and cost-effective LDF hardware.

Binzoni, T.; Leung, T. S.; Rüfenacht, D.; Delpy, D. T.

2006-01-01

131

Optical absorption of pure water in the blue and ultraviolet  

Microsoft Academic Search

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

Zheng Lu

2006-01-01

132

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 5×103-5×104 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

133

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

SciTech Connect

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

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

2012-01-31

134

Experimental octanol\\/water partition coefficients of chlorinated paraffins  

Microsoft Academic Search

Octanol\\/water partition coefficients (KOW) of chlorinated paraffins (CPs) from a commercial mixture (‘Cereclor 60L’) were determined using a “slow-stirring” method. Log KOW values for the different congener groups ranged from 5.85 to 7.14. Equilibrium was reached within a few days, and KOW values were the same at two CP-concentrations. A clear relationship is found between the total number of chlorine

Dick T. H. M. Sijm; Theo L. Sinnige

1995-01-01

135

Air–water interface equilibrium partitioning coefficients of aromatic hydrocarbons  

Microsoft Academic Search

The single equilibration technique was used to determine the equilibrium partitioning coefficients (pc) of an air–water interface for target aromatic volatile organic compounds (VOCs), including benzene, toluene and ethylbenzene. The tested liquid concentrations (CL) of VOC ranged from 0.5 to 20mg\\/l, and the temperatures (Tw) of the solutions were 300, 305, 310 and 315K, respectively. The pc values were calculated

Wen-Hsi Cheng; Fu-Sui Chu; Jia-Jiunn Liou

2003-01-01

136

Separation methods for estimating octanol–water partition coefficients  

Microsoft Academic Search

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

Salwa K Poole; Colin F Poole

2003-01-01

137

Octanol-water partition coefficients of polychlorinated biphenyl congeners  

Microsoft Academic Search

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

Darryl W. Hawker; Des W. Connell

1988-01-01

138

Absorption of water by thin, ionic films of gelatin.  

PubMed

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

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

2004-04-27

139

Effect of Internal Heat Recovery in Ammonia-Water Absorption Cooling Cycles: Exergy and Structural Analysis  

Microsoft Academic Search

First and second law analysis have been conducted for three low temperature driven ammonia-water absorption cooling cycles with increasing internal heat recovery. Based on the results of exergy analysis the structural analysis has been achieved. The obtained Coefficients of Structural Bonds (CSB) consider how the irreversibility of the whole cycle is affected by a change in the irreversibility related to

Dieter Boer; Berhane Hagos Gebreslassie; Marc Medrano; Miquel Nogués

140

Absorption of radio waves by water vapor in the atmospheres of Venus and Mars  

Microsoft Academic Search

In this paper, we shall consider the quantitative relationships between the absorption coefficients of monomeric and dimeric molecules of water vapor in the atmospheres of Venus and Mars. This problem is of interest in the analysis of the conditions for the propagation of electromagnetic waves with wavelengths X ~ 0.7 mm [5] in the atmospheres of these planets and for

A. A. Viktorova; A. P. Naumov

1969-01-01

141

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

142

Effects of the absorption coefficient on the refractive index of germanium in a fiber optic-semiconductor temperature sensor  

NASA Astrophysics Data System (ADS)

This paper introduces a theoretical model which reveals the relation between the absorption and the refractive index of germanium within absorption region, which is crucial to a new fiber optic-semiconductor film temperature sensor developed lately in our lab. The new designed sensor is based on the effect of the temperature dependence of the refractive index of semiconductor. Many efforts on the effect of the temperature-dependent refractive index of semiconductor are reported in transparent region mostly by empirical model such as Sellmeier model[1]. We analyze the temperature dependence of the refractive index of semiconductor near the absorption edge other than in the transparent region. From the Kramers-Kronig relations, the refractive index is an integral of the absorption coefficient over the whole energy spectrum.Taking advantage of the model that explained the contribution of the integral cloesd to the absorption edge to the refractive index by Frank Stern [2] we are able to calculate the variation of the refractive index due to the thermal shift of absorption edge. The contribution of the temperature-dependent absorption coefficient to the refractive index is enhanced dramatically at the absorption edge of semiconductor, where the temperature dependence of the energy gap Eg can be used to get the absorption edge shift with Yu-Brook's model[3]. While the contribution of the absorption shift far away from the absorption edge to ?n is negligible comparing to that near the edge according to Frank Stern[2]. Further demonstration experiments will be carried out to support our theory, in which refractive indexes of germanium are measured at specific wavelengths of 1310nm, 1550nm and 2000nm. Since the direct absorption edge of germanium is at about 0.82eV, corresponding to the wavelength of 1550nm, we estimate that the thermo-optic coefficient dn/dT of germanium at 1550nm would be larger than that at 1310nm and 2000nm.

Peng, Liu; Min, Li; Zhong, Pan

2011-11-01

143

Heating rates and absorption coefficients for electron-cyclotron heating in the Constance 2 mirror experiment  

SciTech Connect

This report presents and discusses the calculation of heating rates and absorption coefficients of electron cyclotron waves in a mirror. In particular, the scaling of the heating rates with resonant zone location and plasma density are calculated since this scaling can be compared with the measurements made on the Constance 2 mirror experiment. Both geometric and Doppler broadening are included by making the substitution ..delta omega../sup 2/ equivalent (..omega..N/sub parallel/..beta..)/sup 2/ ..-->.. (..omega..N/sub parallel/..beta..)/sup 2/ + where is the average transit time of electrons through the resonance layer. The energy transfer between the waves and the electrons are calculated with the same bounce-averaged resonance function used in a Fokker-Plank code. A simple scaling law for the heating rate is shown to be consistent with the Fokker-Plank results for Maxwellian electrons.

Mauel, M.E.

1982-04-01

144

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

145

Influence of colloids on sediment-water partition coefficients of polychlorobiphenyl congeners in natural waters  

Microsoft Academic Search

Measurements of sediment-water partitioning of polychlorobiphenyl (PCB) congeners in Lake Superior provide some of the first field evidence demonstrating the importance of colloids to the fates of highly hydrophobic organic pollutants. Laboratory-derived correlations between sediment-water distribution coefficients and properties of both the contaminant (octanol-water partition coefficient) and the suspended solids (organic carbon content, concentration) do not accurately predict PCB speciation

Joel E. Baker; Paul D. Capel; Steven J. Eisenreich

1986-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

147

Brightness temperature and coefficient of continuous absorption in the solar photosphere  

SciTech Connect

A method used earlier by the author for a matching analysis of the radiation of a black body and a ribbon-filament lamp (G. F. Sitnik, Vestn. Mosk. Univ. Ser. Fiz.-Mat. Nauk No. 1, 63 (1956); G. F. Sitnik, Astron. Zh., 37, 79 (1960); 39, 116 (1962); 39, 715 (1962)) is applied to an analysis of the results of absolute measurements of solar radiation (G. F. Sitnik, Astron. Tsirk. No. 292, 1 (1964); Astron. Zh. 42, 59 (1965)). The following facts are established from the observational data alone: a) no one point of the solar disk, not to mention the disk as a whole, emits as a black body, since otherwise its brightness temperature would be the same for all wavelengths; b) continuous absorption, whose source is negative hydrogen ions, actually dominates in the region of 4800 A absorption exists in the spectral region of lambda< or =4800 A. The additional opacity caused by it intensifies with a decrease in temperature, which is indicated by the data of a joint analysis of its behavior in the photosphere at different distances from the center of the solar disk, in solar faculae, and in sunspots. Possible uncertainties in the initial observational results are discussed which characterize not only their internal convergence but also the departure from the theoretical thermodynamic scale, which is important in any comparison of theoretical calculations with absolute radiation measurements. It is shown that these uncertainties cannot distort the observed actual wavelength dependence of the coefficient of continuous absorption. The preliminary conclusion is drawn that the probable additional source of opacity in the solar photosphere in the region of lambda< or =4800 A may be diatomic molecules.

Sitnik, G.F.

1978-11-01

148

Measurement of Small-Signal Absorption Coefficient and Absorption Cross Section of Collagen for 193-nm Excimer Laser Light and the Role of Collagen in Tissue Ablation  

NASA Astrophysics Data System (ADS)

A 193-nm ArF excimer laser transmission was measured at subablative fluence through varying strength solutions of dissolved collagen, yielding an absorption cross section of 1.14 × 10^-17 cm2 for the peptide bond, which accounts for 96% of the total collagen attenuation that is based on additional transmission measurements through solutions of isolated constituent amino acids. The measured absorption cross sections, in combination with typical corneal tissue composition, yield a predicted corneal tissue absorption coefficient of 16,000 cm^-1. In addition, dry collagen films were prepared and ablation-rate data were recorded as a function of laser fluence. Ablation rates were modeled by use of a Beer-Lambert blow-off model, incorporating a measured ablation threshold and an absorption coefficient that are based on the measured collagen absorption cross section and the film bond density. The measured ablation rates and those predicted by the model were in very good agreement. The experiments suggest that collagen-based absorption coefficients are consistent with predicted corneal tissue ablation rates and previously observed dynamic changes in tissue properties under ablative conditions.

Fisher, Brian T.; Hahn, David W.

2004-10-01

149

Temperature imaging of water in a microchannel using thermal sensitivity of near-infrared absorption.  

PubMed

This paper presents a remote and preparation-free method of temperature imaging of aqueous solutions in microchannels of microfluidic chips. The principle of this method is based on the temperature dependency of the near-infrared (NIR) absorption band (?(2) + ?(3) band) of water. Temperature images were constructed from absorbances in a narrow wavelength range including 1908 nm, the most sensitive to temperature in the band, measured by using an NIR camera and an optical narrow-bandpass filter. Calculation and calibration results demonstrated a linear relationship between the absorption coefficient and temperature with a temperature coefficient of 1.5 × 10(-2) K(-1) mm(-1). Temperature images of 50 ?m thick water in a Y-shaped PDMS microchannel locally heated by a neighboring hot wire were obtained, in which thermal diffusion processes in the microchip were visualized. Temperature resolution was estimated to be approximately 0.2 K according to the temperature coefficient and noise level. PMID:21869986

Kakuta, Naoto; Fukuhara, Yuko; Kondo, Katsuya; Arimoto, Hidenobu; Yamada, Yukio

2011-08-25

150

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

151

Temperature dependence of radio wave absorption by atmospheric water vapors at wavelengths ranging from 10 cm to 0.27 mm  

Microsoft Academic Search

The absorption coefficients are calculated for a constant air pressure and a constant relative water-vapor volume concentration for temperatures between 173 and 373 K. The computed data are used to calculate the temperature dependence of absorption on the wavelength in the centimeter, millimeter, and submillimeter range. The temperature coefficient is found to range from 3.2 to 4 in the atmospheric

K. A. Aganbekian; A. Iu. Zrazhevskii; V. G. Malinkin

1975-01-01

152

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 ...

153

Atmospheric absorption of radio waves in the region of the rotational resonance of water vapor at ??1.35 cm  

Microsoft Academic Search

UDC 621.371.246 An experimental study is reported of the vertical absorption of radio waves with X ~ 1.25 cm by atmospheric water molecules and oxygen, using the intrinsic radio emission of the atmosphere. It is shown that the absorption coefficient of tt20 vapor near the rotational resonance at X -~ 1.35 cm, obtained from measurements of vertical absorption on the

V. M. Plechkov

1969-01-01

154

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

155

The influence of the Ramsauer-Townsend effect on free-free absorption coefficients of the negative argon ion at far infrared wavelengths  

NASA Astrophysics Data System (ADS)

0953-4075/31/1/009/img1 free-free absorption coefficients in the far-IR are calculated using relativistic continuum wavefunctions from solutions of the Dirac equation. Absorption coefficients are shown to exhibit a Ramsauer-Townsend minimum near 1200 K. We compare these results with coefficients derived from non-relativistic and experimental atomic data.

John, T. L.

1998-01-01

156

Measurement of Pressure-Induced Broadening and Shift Coefficients of Carbon Dioxide Absorption Lines around 1.6 mum for using Differential Absorption Lidar  

Microsoft Academic Search

A precise measurement of the vertical profiles of carbon dioxide is required for reducing the uncertainty in the carbon budget. In order to achieve measurements of the vertical CO2 distribution with an uncertainty better than approximately 4 ppm, a precise knowledge of the pressure-dependent broadening and shift coefficients of CO2 absorption lines is indispensable. In this paper, we report the

Daisuke Sakaizawa; Chikao Nagasawa; Tomohiro Nagai; Makoto Abo; Yasukuni Shibata; Masahisa Nakazato

2008-01-01

157

Near-IR absorption of water vapor: Pressure dependence of line strengths and an upper limit for continuum absorption  

NASA Astrophysics Data System (ADS)

Water vapor absorption cross-sections in the near-infrared region (10 500-10 800 cm-1) were measured using cavity ringdown spectroscopy. Linestrengths were measured for several absorption lines around 10 604 cm-1 (943 nm) between 500 and 850 Torr of N2 and found to be independent of pressure. Our measured linestrengths of these individual lines agree well with values from databases such as HITRAN and the ESA-WVR, which are currently used for atmospheric calculations, but the integrated strength over the entire measured spectral region is slightly larger than that contained in these databases. Water vapor pressure-broadening coefficients due to nitrogen were also estimated from these measurements. The absorption due to water vapor continuum was determined to be less than (9.2 ± 0.2) × 10-27 cm2 molecule-1 at 11 500 cm-1. This measured upper limit, though larger than the estimated values from continuum models, would not contribute significantly to the calculated radiation absorption in this wavelength region.

Aldener, M.; Brown, S. S.; Stark, H.; Daniel, J. S.; Ravishankara, A. R.

2005-08-01

158

Absorption coefficient of intersubband transition at 1.55 µm in (CdS/ZnSe)/BeTe quantum wells  

NASA Astrophysics Data System (ADS)

In this paper, the intersubband optical absorption coefficient is calculated in a ZnSe/CdS/ZnSe quantum well (QW) surrounded by BeTe barriers. First, the one-dimensional Poisson and Schrödinger equations have been solved self-consistently, and then the intersubband optical absorption between the lowest two levels has been theoretically studied under an external electric field. Simulated results including eigenvalues, absorption coefficient and electroabsorption properties have been discussed. The structure under investigation covers a large range of the electromagnetic spectra including the visible and near infrared (IR). For the 1.55 µm wavelength (0.8 eV), dependences of the intersubband optical absorption coefficient on the applied electric field, thickness of the barrier and concentration of doping are investigated. Our calculation shows that for an applied electric field lower than a critical value of around 100 kV cm-1, the ITSB optical absorption peak undergoes a red shift with the increase in the electric field. However, for an applied electric field above the critical value, the electrons move to the same side of the well for all states. The energy difference E2 - E1 increases leading to a blue shift of the absorption peak. As a result, the optical intersubband transition enhances its intensity. Taking into account the present results, we hope that important IR photodetectors and near-IR laser amplifiers can be constructed based on the group II-VI QWs.

Sfina, N.; Abdi-Ben Nasrallah, S.; Mnasri, S.; Said, M.

2009-02-01

159

A coefficient to characterize mixing in solar water storage tanks  

SciTech Connect

A dimensionless coefficient is developed to characterize the level of mixing in solar water storage tanks. The MIX number, based on the height weighted energy, or moment of energy, in the tank, ranges from 0 to 1, with 0 representing a perfectly stratified (unmixed) tank and 1 representing a fully mixed tank. Limiting values are based on theoretical determinations of the maximum and minimum values of the moment of energy in a tank without mixing and a tank with complete mixing, respectively. Use of the new MIX number is illustrated by experimental data obtained in a 372-liter storage tank operated with both a conventional drop-tube inlet and a rigid, porous stratification manifold. The initial tank temperature profile, the temperature of the water entering the tank, and test duration are varied in three testing schemes. Fluid mixing is quantified by measured vertical temperature profiles and the dimensionless MIX number.

Davidson, J.H. (Univ. of Minnesota, Minneapolis, MN (United States). Mechanical Engineering Dept.); Adams, D.A.; Miller, J.A. (Colorado State Univ., Fort Collins, CO (United States). Solar Energy Applications Lab.)

1994-05-01

160

Absorption refrigeration: cooling with hot water  

Microsoft Academic Search

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

Rafferty

1984-01-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

162

Optical absorption properties of water components in Xixi wetland of Hangzhou  

NASA Astrophysics Data System (ADS)

Water optical properties are important factors that affect phytoplankton biomass, carbon formation and carbon output of the upper body. Water spectral absorption properties are among the most important inherent optical properties. This paper was a preliminary analysis on spectral absorption properties of water suspended particle, de-pigmented particle, pigment particle and chromophoric dissolved organic matter (CDOM) in main channel of Hangzhou Xixi Wetland National Park phase I. The results indicate that the absorption spectrum of suspended particle is similar to the de-pigmented particle, while the absorption spectrum of pigment particle is almost submerged in the de-pigmented particle; The absorption spectrum of de-pigmented particle and CDOM follows the exponential decay law, the former slope Sd average value of the exponential function in the range of 400-700nm is 9.56+/-0.86?m-1, the latter slope Sgaverage value of the exponential function in the range of 400-500nm is 14.28+/-1.23?m-1. The absorption peak of chlorophyll a of pigment particle near 440nm is virtually not existent and also very weak at 675nm. According to the absorption contribution rate of each component to the total absorption, de-pigmented particle is the greater contributor than pigment particle and CDOM in this field campaign. In addition, according to water mass classification based on the contribution rate of absorption coefficient at 440nm, vast majority of the water body in study area could be classified into the most optical complex water mass type.

Zhou, Fangfang; Zhou, Bin; Zhu, Weiping; Dou, Wenjie; Ling, Zaiying

2010-09-01

163

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

164

Molecular Dynamics Simulation of Diffusion Coefficients of Oxygen, Nitrogen and Sodium Chloride in Supercritical Water  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation has been performed to determine the infinite-dilution diffusion coefficients of oxygen and nitrogen, and the diffusion coefficients of NaCl in supercritical water from 703.2-763.2 K and 30-45 MPa. The results obtained show that the diffusion coefficients in supercritical water increase with temperature, while decreasing with pressure. Nevertheless, the diffusion coefficients in supercritical water are much larger than those in normal water.

Xiao, Ji; Lu, Jiu-Fang; Chen, Jian; Li, Yi-Gui

2001-07-01

165

Monitoring of Water Content And Frozen State by using Millimeter Wave Absorption Features  

NASA Astrophysics Data System (ADS)

In this research, we built an experimental setup for measuring the water content in plants and food, and for determining the water/ice state of a sample. The setup consists of a 35 GHz Gunn oscillator producing about 10 mW of output power, two horn antennas and a power meter. We have checked that the absorption of a leaf is directly proportional to its water content, and we could show how changes of the water content depend on photosynthesis, by intermittent illumination with a white fluorescent lamp. In another direction of research, we verified that the difference in the absorption coefficients for water and ice is significant, and we could discriminate and monitor the frozen state of water and food material. All these experiments demonstrate the possibility of applying millimeter waves to fields such as botany, agriculture, and food industry.

Mizuno, Maya; Shindo, Kenji; Ogawa, Yuichi; Otani, Chiko; Kawase, Kodo

166

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

167

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

Microsoft Academic Search

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

E Mészáros; A Molnár; J Ogren

1998-01-01

168

Absorption of hydrophobic compounds into the poly(dimethylsiloxane) coating of solid-phase microextraction fibers: high partition coefficients and fluorescence microscopy images.  

PubMed

The use of solid-phase microextraction with poly(dimethylsiloxane) (PDMS)-coated glass fibers for the extraction and analysis of hydrophobic organic analytes is increasing. The literature on this topic is characterized by large discrepancies in partition coefficients and an uncertainty of whether highly hydrophobic analytes are retained by absorption into the fiber coating or by adsorption to the fiber surface. We applied a new method, which minimizes the impact of experimental artifacts, to determine PDMS water partition coefficients of 17 hydrophobic analytes including chlorinated benzenes, PCBs, PAHs, and p,p'-DDE. These partition coefficients are several orders of magnitude higher than some reported values. Two observations strongly suggest that the retention of hydrophobic organic substances is governed by partitioning into the PDMS coating. (1) The partition coefficients are proportional with octanol/water partition coefficients. (2) The fluorescence of fluoranthene was observed to be homogeneously distributed within the polymer coating when studied by means of fluorescence microscopy. Implications of these findings for the application of solid-phase microextraction with respect to potential detection limits, with respect to biomimetic extraction, and with respect to measurements in multicompartment systems are discussed. PMID:10695129

Mayer, P; Vaes, W H; Hermens, J L

2000-02-01

169

Estimation of Water Solubility and Octanol/Water Partition Coefficient of Hydrophobic Dyes. Part 1. Relationship between Solubility and Partition Coefficient.  

National Technical Information Service (NTIS)

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

G. L. Baughman E. J. Weber

1991-01-01

170

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

171

Investigations of the 1 KHz Sound Absorption in Sea Water.  

National Technical Information Service (NTIS)

Using a combination of sound absorption data from a large spherical resonator and relaxation frequency data from the temperature jump technique, it has been demonstrated that there is an increased sound absorption in sea water below approximately 1 kHz. T...

V. P. Simmons

1983-01-01

172

Specific absorption coefficient and phytoplankton biomass in the southern region of the California Current  

NASA Astrophysics Data System (ADS)

In recent years, experts of optical hydrology have shown great interest in the variability of the specific absorption coefficient of light by phytoplankton ( aph*). This parameter is important and necessary for comparing in situ bio-optical and satellite optical measurements. Such comparisons are needed for detecting primary productivity at a mesoscale level. At present, however, the parameters used in algorithms for predicting productivity are global averages. To avoid this bias, we measured the spatial-temporal variability of aph* as part of the Jan-01 Investigaciones Mexicanas de la Corriente de California cruise along the southern California Current. We observed median values of 0.041 m 2 (mg chlorophyll a (Chl a)) -1 at 440 nm and 0.015 at 674 nm, with significant differences between inshore and offshore stations. In general, the stations located in the area of Bahía Vizcaíno, with oceanographic conditions favorable for the growth of phytoplankton, showed lower values of the aph*. The nano-microphytoplankton (>5 ?m) community comprised of 26 diatom genera with mean abundance values of the 19.5×10 3 cells l -1. Nitzschia closterium, a pennate diatom, was almost uniform throughout the study region. Flow cytometry measurements indicated that the picoplankton (<5 ?m) community consisted of two prokaryotes, Prochlorococcus (mean 3.6×10 6 cells l -1) and Synechococcus (mean 10.4×10 6 cells l -1), and a mixture of picoeukaryotes (mean 6.5×10 6 cells l -1). Analyses of Chl and carotenoid pigments determined by high-performance liquid chromatographic confirmed the presence of the divinyl Chl a characteristic of Prochlorococcus. The nano-micro- and picoplankton were 82% and 18% of total phytoplankton biomass (?g C l -1), respectively. In general, we concluded that the phytoplankton community structure and biomass on this cruise showed conditions similar to oligotrophic systems.

Millán-Núñez, Eduardo; Sieracki, Michael E.; Millán-Núñez, Roberto; Lara-Lara, José Rubén; Gaxiola-Castro, Gilberto; Trees, Charles C.

2004-03-01

173

Measurement of integrated absorption cross-section, oscillator strength and number density of caffeine in coffee beans by integrated absorption coefficient technique  

Microsoft Academic Search

Integrated absorption cross-section and oscillator strength of caffeine in water and dichloromethane were reported by UV–Vis spectrometer in the wave number regions of 20,000–39,062cm?1 at room temperature. The integrated absorption cross-section of caffeine in water and dichloromethane in these wave number regions were (4.44±0.18)×107 and (4.32±0.11)×107L mol?1cm?2, respectively. The corresponding calculated value for oscillator strength of caffeine in water and

Abebe Belay

2010-01-01

174

Water Vapor Differential Absorption LIDAR Design for Unpiloted Aerial Vehicles.  

National Technical Information Service (NTIS)

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 c...

P. F. Mead R. J. DeYoung

2005-01-01

175

Critical water content and water stress coefficient of soybean ( Glycine max [L.] Merr.) under deficit irrigation  

Microsoft Academic Search

The objective of this research was to investigate the critical water content (?\\u000a c) and water stress coefficient (K\\u000a s) of soybean plant under deficit irrigation. This research was conducted in a plastic house at the University of Lampung,\\u000a Sumatra in Indonesia from June to September 2000. The water deficit levels were 0–20%, 20–40%, 40–60%, 60–80%, and 80–100%\\u000a of available

R. A. Bustomi Rosadi; Masateru Senge; Kengo Ito; John T. Adomako

2005-01-01

176

Cycle Simulation of HotWater Fired Absorption Chiller  

NASA Astrophysics Data System (ADS)

The design limits were examined to determine the lowest temperature for hot water that can be used as a heat source to drive a hot water fired absorption chiller. Advantage was taken of the fact that the cycle calculation method using the minimum temperature difference is quite effective. This minimum temperature difference was the lower of the two temperature differences used to get the logarithmic mean temperature difference that need to design the evaporator, absorber, condenser and generator in an absorption refrigerator. This report proposes a new solution algorithm employing this minimum temperature difference to make a cycle simulation of the hot water fired absorption chiller. It shows the lowest usable temperature for hot water and makes clear the chilled water and cooling water temperature conditions that can provide the lowest temperature.

Esaki, Shuji; Iramina, Kazuyasu; Kobayashi, Takahiro; Ohnou, Masayuki; Kaneko, Toshiyuki; Soga, Takashi

177

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

NASA Astrophysics Data System (ADS)

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

Zheng, Guangming; Stramski, Dariusz

2013-06-01

178

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

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

179

Second law based thermodynamic analysis of ammonia?water absorption systems  

Microsoft Academic Search

The second law of thermodynamics is used to study the performance of single-stage and two-stage ammonia-water absorption refrigeration systems (ARSs) when some input design parameters are varied. The entropy generation of each component and the total entropy generation ð _ StotÞ of all the system components as well as the coefficient of performance (COP) of the ARSs are calculated from

S. A. Adewusi; Syed M. Zubair

2004-01-01

180

Diffusion coefficients of methanol and water and the mutual diffusion coefficient in methanol-water solutions at 278 and 298 K  

SciTech Connect

Diffusion coefficients have been measured for methanol and water in their mixtures over the full composition range at 278.15 and 298.15 K. By defining a reduced coefficient D/sup +/+/ for each component an extensive correlation in diffusional behavior has been identified for the two species. The correlation increases with decreasing temperature. Examination of literature data for acetonitrile-water and acetone-water at 298.15 K shows that similar correlations are not present in those systems. Data are also reported for the mutual diffusion coefficients for the methanol-water system at both temperatures and these are used to obtain velocity correlation coefficients. The Albright equation relating the shear viscosity of a mixture to the diffusion coefficients of its components is examined by using the diffusion data and an interaction parameter introduced. 21 references, 5 figures, 5 tables.

Derlacki, Z.J.; Easteal, A.J.; Edge, A.V.J.; Woolf, L.A.; Roksandic, Z.

1985-11-21

181

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

182

Multi-resolution error analysis of predicted absorption coefficients. Method and application to the infrared spectrum of methane at high temperature  

Microsoft Academic Search

A general method for the estimation of the confidence interval of molecular absorption coefficients is presented. Statistical numerical experiments are implemented to quantify the propagation of errors from line parameters to absorption coefficients as a function of the resolution. The method uses line parameter predictions (position and intensity) with estimated uncertainties derived from global polyad models. This work is especially

Ch. Wenger; J. P. Champion

2010-01-01

183

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

PubMed

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

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

2013-03-01

184

Diffusion coefficients of methanol and water and the mutual diffusion coefficient in methanol-water solutions at 278 and 298 K  

Microsoft Academic Search

Diffusion coefficients have been measured for methanol and water in their mixtures over the full composition range at 278.15 and 298.15 K. By defining a reduced coefficient D\\/sup +\\/+\\/ for each component an extensive correlation in diffusional behavior has been identified for the two species. The correlation increases with decreasing temperature. Examination of literature data for acetonitrile-water and acetone-water at

Z. J. Derlacki; A. J. Easteal; A. V. J. Edge; L. A. Woolf; Z. Roksandic

1985-01-01

185

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

2010-07-22

186

Estimating effects of processing conditions and variable properties upon pool shape, cooling rates, and absorption coefficient in laser welding  

Microsoft Academic Search

This paper examines the role of traverse speed, Beer–Lambert absorption coefficient ?, surface reflectivity, and changing liquid thermal conductivity upon the shape of the melt pool and the cooling rates that occur. The dependence of ? upon processing conditions is also examined. A three-dimensional variable property, moving heat source, quasi-steady-state, finite difference model for heat conduction into the substrate during

T. Chande; J. Mazumder

1984-01-01

187

Study of magnesium and aluminum alloys absorption coefficient during Nd:YAG laser interaction  

Microsoft Academic Search

In laser processes, the absorption factor of laser Nd:YAG by metals plays a very important role. In order to model laser welding, we need to know its evolution during the process. The theoretical calculation does not enable the prediction of the absorption factor in the case of a keyhole mode. It is difficult to predict the effect of plasma and

Nicolas Pierron; Pierre Sallamand; Simone Matteï

2007-01-01

188

Ozone absorption in water: Mass transfer and solubility  

Microsoft Academic Search

Mass Transfer of ozone absorbed by water in a semi-continuous stirred reactor is studied at the lab scale. Experimental investigation using a complete factorial scheme shows a predominant effect of agitation speed and gas flow and results in a correlation for the mass transfer coefficient, kâa. Solubility of ozone in water is estimated by evaluation of an apparent Henry's law

A. Ouederni; J. C. Mora; R. S. Bes

2009-01-01

189

Ozone Absorption in Water: Mass Transfer and Solubility  

Microsoft Academic Search

Mass Transfer of ozone absorbed by water in a semi-comtinuous stirred reactor is studied at the lab scale. Experimental investigation using a complete factorial scheme shows a predominant effect of agitation speed and gas flow and results in a correlation for the mass transfer coefficient, k1a. Solubility of ozone in water is estimated by evaluation of an apparent Henry's law

A. Ouederni; J. C. Mora; R. S. Bes

1987-01-01

190

Low-temperature FIR and submillimetre mass absorption coefficient of interstellar silicate dust analogues  

NASA Astrophysics Data System (ADS)

Context. Cold dust grains are responsible for the far-infrared and submillimetre (FIR/submm) emission observed by Herschel and Planck. Their thermal emission is usually expressed as a modified black body law in which the FIR/submm dust opacity, or mass absorption coefficient (MAC), is described by the MAC at a given wavelength ??0 and the temperature- and wavelength-independent emissivity spectral index ?. However, numerous data from previous space and balloon-borne missions and recently from Herschel and Planck show that the dust emission is not well understood, as revealed for example by the observed anti-correlation of ? with the grain temperature. Aims: The aim of this work is to measure the optical properties of interstellar dust analogues at low temperatures to give astronomers the necessary data for interpreting FIR/submm observations such as those from the Herschel and Planck satellites. Methods: We synthesised, via sol-gel methods, analogues of interstellar amorphous silicate grains, rich in Mg and Ca, and having stoichiometry of olivine and pyroxene. The samples are characterised by various techniques to determine their composition, size, amorphisation degree. All the amorphous samples are annealed at 1100 °C to study the crystallised materials for comparison. We measured the MAC of all the samples in the 2-25 ?m range at room temperature and in the 100-1000/1500 ?m range for grain temperatures varying from 300 to 10 K. Results: The experimental results show that, for all the amorphous samples, the grain MAC decreases when the grain temperature decreases and that the local spectral index, ?, defined as the slope of the MAC curve, is anti-correlated with the grain temperature. These variations, which are not observed in the crystallised samples, are related to the amorphous nature of the samples. In addition, the spectral shape of the MAC is complex and cannot be described by a single spectral index over the 100-1500 ?m range. At short wavelengths (? ? 500/700 ?m), ? is in the range 1.6-2.1 for all grain temperature and grain composition. However, at longer wavelengths (? ? 500/700 ?m), ? ? 2 for samples with a pyroxene stoichiometry and ? ? 2 for samples with an olivine stoichiometry. Conclusions: The dust properties in the FIR/submm domain and at low temperature are more complicated than expected. The simplifying asymptotic expression based on a single temperature- and wavelength-independent spectral index used by astronomers is not appropriate to describe the dust MAC, hence the dust emission, and may induce significant errors on the derived parameters, such as the dust mass and the dust physical and chemical properties. Instead, dust emission models should use the dust MAC as a function of wavelength and temperature.

Coupeaud, A.; Demyk, K.; Meny, C.; Nayral, C.; Delpech, F.; Leroux, H.; Depecker, C.; Creff, G.; Brubach, J.-B.; Roy, P.

2011-11-01

191

Some problems in the calculation and measurement of the absorption of millimeter and submillimeter waves in atmospheric water vapor  

Microsoft Academic Search

Recent measurements of the absorption coefficient of water vapor in the transparent windows of the submillimeter wave region (X > 60g) exceed earlier calculated values by a factor of 1.5-2, i.e., there is a discrepancy between theory and experiment similar to that existing in the millimeter wave region (2 ~< <~k~< 8 mm) A short discussion is given of the

S. A. Zhevakin; A. P. Naumov

1965-01-01

192

Dependence of the water vapor diffusion coefficient of aspen ( Populus spec. ) on moisture content  

Microsoft Academic Search

The dependence of the diffusion coefficient of water in aspen (Populus sp.) on moisture content over the range of 0 to 18 percent moisture content at 43 °C was determined. The method requires a series of adsorption experiments and application of a numerical method for solving the diffusion equation with a moisture-content-dependent diffusion coefficient. The diffusion coefficient was found to

W. T. Simpson; J. Y. Liu

1991-01-01

193

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

194

Absorption coefficient modeling of microcrystalline silicon thin film using Maxwell-Garnett effective medium theory.  

PubMed

Considering the Mott-Davis density of state model and Rayleigh scattering effect, we present an approach to model the absorption profile of microcrystalline silicon thin films in this paper. Maxwell-Garnett effective medium theory was applied to analyze the absorption curves. To validate the model, several experimental profiles have been established and compared with those results from the model. With the assistance of the genetic algorithm, our results show that the absorption curves from the model are in good agreement with the experiments. Our findings also indicate that, as the crystal volume fraction increases, not only do the defects in amorphous silicon reduce, but the bulk scattering effect is gradually enhanced as well. PMID:22418668

Chen, Sheng-Hui; Wang, Hsuan-Wen; Chang, Ting-Wei

2012-03-12

195

Near-Infrared Studies of Glucose and Sucrose in Aqueous Solutions: Water Displacement Effect and Red Shift in Water Absorption from Water-Solute Interaction  

NASA Astrophysics Data System (ADS)

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

Jung, Youngeui; Hwang, Jungseek

2013-02-01

196

Assessment of the relationships between dominant cell size in natural phytoplankton communities and the spectral shape of the absorption coefficient  

Microsoft Academic Search

Size-fractionated chlorophyll concentration and phytoplankton absorption spectra were compared for a wide variety of natural communities. We found that, in general, when phytoplankton abundance increases, larger size- classes are added incrementally to a background of smaller cells. Natural phytoplankton communities from surface waters were explicitly characterized according to their dominant cell size and taxonomic group, and the relationships between this

Aurea M. Ciotti; Marlon R. Lewis; John J. Cullen

2002-01-01

197

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

Microsoft Academic Search

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

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

2006-01-01

198

Water cooled absorption chillers for solar cooling applications  

NASA Astrophysics Data System (ADS)

A broad line of absorption chillers designed to operate with hot fluids at as low a temperature as practical while rejecting heat to a stream of water was developed. A packaging concept for solar application in which controls, pumps, valves and other system components could be factor assembled into a unitary solar module was investigated.

Biermann, W. J.; Reimann, R. C.

1982-03-01

199

Continuous solar air conditioning with ammonia\\/water absorption cycle  

Microsoft Academic Search

The considered cycle involves the replacement of the vapor compression function of a conventional compressor with a generator, absorber, and a circulation pump. The generator utilizes heat to produce a refrigerant vapor at high pressure. This vapor is condensed and expanded for cooling. The refrigerant combines subsequently with an absorbant and is returned to the generator. The ammonia\\/water absorption cycle

E. A. Farber; C. A. Morrison; H. A. Ingley; J. A. Clark

1976-01-01

200

Influence of microcracking on water absorption and sorptivity of ECC  

Microsoft Academic Search

This paper presents the results of an experimental investigation on the water absorption and sorptivity properties of mechanically loaded Engineered Cementitious Composites (ECC). ECC is a newly developed high performance fiber rein- forced cementitious composite with substantial benefit in both high ductility and improved durability due to tight crack width. By employing microme- chanics-based material design, ductility in excess of

Mustafa Sahmaran; Æ Victor; C. Li

201

A comparison between ammonia-water and water-lithium bromide solutions in vapor absorption refrigeration systems  

SciTech Connect

A Vapor Absorption Refrigeration (VAR) System is similar to a Vapor Compression Refrigeration (VCR) System. In both systems the required refrigeration is provided by refrigerants vaporizing in the evaporator. However, in the VAR System, a physico-chemical process replaces the mechanical process of the VCR system and heat rather than a mechanical and electrical energy is used. The advantages of this system lie in the possibility of utilizing of waste energy from industrial plants as well as of using solar energy. The study included an investigation to analyze the Vapor Absorption Refrigeration systems using ammonia-water and water-lithium bromide solutions. A fundamental VAR system is described and the operating sequence is explained. Since the most common VAR systems use ammonia-water solution with ammonia as the refrigerant and water-lithium bromide solution with water as the refrigerant, the comparison of the two is presented in respect of the coefficient of performance (COP), the cooling capacity and the maximum and minimum system pressures. It is concluded that the VAR system using water-lithium bromide solution provided better performance than the system using ammonia-water solution. However, there are some points to be considered such as: the danger of crystallization and impossibility of operating in very low temperatures because of the use of water as the refrigerant.

Horuz, I. [Univ. of Uludag, Bursa (Turkey)

1998-07-01

202

Water absorption and swelling of glass\\/epoxy syntactic foams  

Microsoft Academic Search

The results of experimental and theoretical investigation of glass\\/epoxy syntactic foams at a long-term (10 years) exposure in water are presented. Specimens for experimental investigation were made from EDT-10 epoxy filled with MSO-779 hollow glass spheres. Seven types of specimens with filler volume fraction varying from 0 to 0.6 were tested. The curves of long-term water absorption and swelling were

V. A. Kochetkov; R. D. Maksimov

1996-01-01

203

Activity coefficients of chlorophenols in water at infinite dilution  

SciTech Connect

The total pressure of aqueous solutions of chlorophenols was determined by a ebulliometric total pressure method for the aqueous solutions of phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol in the temperature range from 40 to 90 C. The activity coefficients at infinite dilution and the Henry constants were derived.

Tabai, S.; Rogalski, M. [Univ. de Metz (France). Lab. de Thermodynamique et d`Analyse Chimique; Solimando, R. [INPL-ENSIC, Nancy (France). Lab. de Thermodynamique Chimique Appliquee; Malanowski, S.K. [Inst. Chemii Fizycznej PAN, Warszawa (Poland)

1997-11-01

204

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

NASA Astrophysics Data System (ADS)

The light absorption properties of particulate and dissolved materials strongly influence the propagation of visible light in oceanic waters and therefore the accuracy of ocean color algorithms. While the general absorption properties of these materials have been reported for Arctic waters, their seasonal variability remains unknown. We investigated the light absorption coefficients of phytoplankton [a?(?)], nonalgal particles [aNAP(?)], and colored dissolved organic matter [aCDOM(?)] in both coastal and oceanic waters of the western Arctic Ocean from spring to autumn. Values for the chlorophyll a-specific absorption coefficient of phytoplankton [a*?(440)] declined significantly from the ice melt period in the early spring to the summer. Using high-performance liquid chromatography, we show that the decrease in a*?(440) was due to a strong package effect that overwhelmed the influence of the pigment composition. A decrease in the aNAP(?) values from spring and summer to autumn likely originated from a decrease in the concentration of phytoplanktonic detritus. The aCDOM(?) near the surface decreased by 34% from spring to summer as a result of photobleaching by solar radiation. The colored dissolved organic matter (CDOM) absorption values then increased significantly during autumn, resulting from the cumulative injection of Alaskan Coastal Waters into the Arctic as well as CDOM generated in situ. Our results suggest that all of the absorption components are tightly linked to biogeochemical processes, and thus the seasonal variability in a?(?), aNAP(?), and aCDOM(?) should be taken into account in bio-optical models.

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

2011-02-01

205

Water Absorption and Thickness Swelling Behavior of Polypropylene Reinforced with Hybrid Recycled Newspaper and Glass Fiber  

NASA Astrophysics Data System (ADS)

This study aims to investigate the moisture absorption of recycled newspaper fiber and recycled newspaper-glass fiber hybrid reinforced polypropylene composites to study their suitability in outdoor applications. In this work composite materials were made from E-glass fiber (G), recycled newspaper (NP) and polypropylene (PP), by using internal mixing and hot-pressing molding. Long-term water absorption (WA) and thickness swelling (TS) kinetics of the composites was investigated with water immersion. It was found that the WA and TS increase with NP content in composite and water immersion time before an equilibrium condition was reached. Composites made from the NP show comparable results as those made of the hybrid fiber. The results suggest that the water absorption and thickness swelling composite decrease with increasing glass fiber contents in hybrid fiber composite. It is interesting to find that the WA and TS can be reduced significantly with incorporation of a coupling agent (maleated polypropylene) in the composite formulation. Further studies were conducted to model the water diffusion and thickness swelling of the composites. Diffusion coefficients and swelling rate parameters in the models were obtained by fitting the model predictions with the experimental data.

Shakeri, Alireza; Ghasemian, Ali

2010-04-01

206

Enhancing the absorption coefficient of a backed rigid frame porous layer by embedding circular periodic inclusions.  

PubMed

The acoustic properties of a porous sheet of medium static air flow resistivity (around 10,000 N m s(-4)), in which a periodic set of circular inclusions is embedded and which is backed by a rigid plate, are investigated. The inclusions and porous skeleton are assumed motionless. Such a structure behaves like a multi-component diffraction grating. Numerical results show that this structure presents a quasi-total (close to unity) absorption peak below the quarter-wavelength resonance of the porous sheet in absence of inclusions. This result is explained by the excitation of a complex trapped mode. When more than one inclusion per spatial period is considered, additional quasi-total absorption peaks are observed. The numerical results, as calculated with the help of the mode-matching method described in this paper, agree with those calculated using a finite element method. PMID:22225034

Groby, J-P; Dazel, O; Duclos, A; Boeckx, L; Kelders, L

2011-12-01

207

A model based on stacked-constraints approach for partitioning the light absorption coefficient of seawater into phytoplankton and non-phytoplankton components  

NASA Astrophysics Data System (ADS)

Partitioning of the total non-water absorption coefficient of seawater, anw(?) (i.e., the light absorption coefficient after subtraction of pure water contribution), into phytoplankton, aph(?), and non-phytoplankton, adg(?), components is important in the areas of ocean optics, biology, and biogeochemistry. We propose a partitioning model based on stacked-constraints approach, which requires input of anw(?) at a minimum of six specific light wavelengths. Compared with existing models, our approach requires much less restrictive assumptions about the spectral slope of adg(?) and the spectral shape of aph(?). Our model is based on several inequality constraints determined from an extensive, quality-verified set of field data covering oceanic and coastal waters from low to high-latitudes. With these constraints, the model first derives a wide range of speculative solutions for adg(?) and aph(?) and then identifies feasible solutions. Final model outputs include the optimal solution and a range of feasible solutions for adg(?) and aph(?). The optimal solutions agree well with measurements. For example, the median ratio of the model-derived optimal solutions to measured adg(?) and aph(?) at 443 nm is very close to 1, i.e., 1.004 and 0.988, respectively. The median absolute percent difference between the optimal solutions and measured values of adg(443) and aph(443) is 6.5% and 12%, respectively. The range of feasible solutions encompasses the measured adg(?) and aph(?) with a probability >90% at most wavelengths. Our results support the prospect for the applications of the partitioning model using the input data of anw(?) collected from various oceanographic and remote-sensing platforms.

Zheng, Guangming; Stramski, Dariusz

2013-04-01

208

Interpretation of nonelectrolyte partition coefficients between dimyristoyl lecithin and water  

Microsoft Academic Search

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

Jared M. Diamond; Yehuda Katz

1974-01-01

209

Modeling sulfur dioxide absorption by fine water spray  

SciTech Connect

A novel theoretical model was developed to determine the removal efficiency of sulfur dioxide using fine water spray. The droplet pH, diameter, S(IV) concentration, sulfur dioxide concentration, and liquid-to-gas ratio are found to influence the absorption of sulfur dioxide by the fine water spray. The results demonstrate that the absorption of sulfur dioxide by the fine water spray increases as the droplet diameter falls. The concentration gradient between the interface of the gaseous and liquid phases causes the absorption of sulfur dioxide by the droplets to increase as the initial S(IV) concentration decreases or the sulfur dioxide concentration increases. The results indicate that the performance of the fine water spray in removing sulfur dioxide is generally improved by reducing the droplet diameter or the initial S(IV) concentration, or by increasing the sulfur dioxide concentration, the droplet pH or the liquid-to-gas ratio. The proposed model reveals the parameters that should be controlled in using a fine water spray device and a method for improving its performance in removing sulfur dioxide.

Cheng-Hsiung Huang [Yuanpei University of Science and Technology, Hsin Chu (Taiwan)

2005-07-01

210

QSAR Study on solubility of alkanes in water and Their partition coefficients in different solvent systems using PI index  

Microsoft Academic Search

The aqueous solubility (Sw) of liquids and solids, expressed as log Sw as well as their partition coefficients in different solvent systems viz. Poct (partition coefficient in octanol-water), P16 (partition coefficient in water-hexadecane), Palk (partition coefficient in water-alkane), and Pcyc (partition coefficient in water-cyclohexane), and aqueous solubility (Sw) have been estimated using the PI (Padmakar–Ivan) index and the results compared

Padmakar V. Khadikar; Dheeraj Mandloi; Amrit V. Bajaj; Sheela Joshi

2003-01-01

211

Multiple-illumination photoacoustic tomography: reconstructing absorption, scattering, and Grüeneisen coefficient distributions  

NASA Astrophysics Data System (ADS)

Photoacoustic imaging is a promising technique combining high ultrasonic resolution and high optical contrast. However, quantification has proved rather challenging. In this paper, we present a non-iterative reconstruction strategy with multiple-optical-sources for reconstruction of absorption, scattering perturbations as well as the spatially varying Grüeneisen parameter from a known turbid background. We term this method the multiple-illumination photoacoustic tomography (MI-PAT). While numerical challenges still exist, we demonstrated that the linearized MI-PAT framework we propose has orders of magnitude improved condition number compared with Continuous-Wave Diffuse Optical Tomography (CW-DOT).

Shao, Peng; Cox, Ben; Zemp, Roger J.

2011-02-01

212

Water vapor absorption in the atmospheric window at 239 GHz  

NASA Astrophysics Data System (ADS)

Absolute absorption rates of pure water vapor and mixtures of water vapor and nitrogen have been measured in the atmospheric window at 239 GHz. The dependence on pressure as well as temperature has been obtained. The experimental data are compared with several theoretical or empirical models, and satisfactory agreement is obtained with the models involving a continuum; in the case of pure water vapor, the continuum contribution based upon recent theoretical developments gives good results. The temperature dependence is stronger than that proposed in a commonly used atmospheric transmission model.

Bauer, A.; Godon, M.; Carlier, J.; Ma, Q.

1995-04-01

213

Absorption of solar radiation by water vapor in clear and cloudy skies: Implications for anomalous absorption  

Microsoft Academic Search

We present ground-based measurements of integrated atmospheric absorption obtained using a zenith-pointing spectrometer for the wavelength region 550-1000 nm. A nonlinear, least squares fitting routine is used to fit the structured and unstructured components of the spectra, including the water vapor bands at 720, 820, and 940 nm. The structured component is found to be well-accounted for by line-by-line calculations

Christian Hill; Roderick L. Jones

2000-01-01

214

Partition Coefficients and Solubilities of Compounds in the Water–Ethanol Solvent System  

Microsoft Academic Search

A new method for the prediction of solubility in the water–ethanol system has been devised. The method is based on the construction\\u000a of equations for the prediction of partition coefficients from water to water–ethanol mixtures, based on the Abraham descriptors\\u000a for compounds. Once partition coefficients have been predicted for a particular compound, only an experimental value for the\\u000a solubility in

Michael H. Abraham; William E. Acree Jr

2011-01-01

215

Experimental study of oxygen diffusion coefficients in clean water containing salt, glucose or surfactant: Consequences on the liquid-side mass transfer coefficients  

Microsoft Academic Search

This present paper proposes new investigations aiming at: (i) studying the effect on oxygen diffusion coefficients of the presence in clean water of some compounds usually encountered in biological media and (ii) quantifying their consequences on liquid-side mass transfer coefficients. The oxygen diffusion coefficients D were firstly measured in various synthetic liquid phases containing either salt (NaCl), sugar (glucose) or

Marupatch Jamnongwong; Karine Loubiere; Nicolas Dietrich; Gilles Hébrard

2010-01-01

216

An Exergy Analysis of LiBr-Water Absorption Refrigerators  

NASA Astrophysics Data System (ADS)

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

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

217

A water vapor monitor using differential infrared absorption  

NASA Astrophysics Data System (ADS)

A water vapor monitor was developed with adequate sensitivity and versatility for a variety of applications. Two applications are the continuous monitoring of water in ambient air and the measuring of the mass of water desorbed from aerosol filters. The sample gas may be held static, or flow continuously through the 56 cc sample cell, temperature controlled at 45 C. Infrared energy from a tungsten-iodide bulb passes through a rotating filter wheel and the sample cell to a PbS detector. The infrared beam passes through the sample gas twice to produce a total optical path of 40 cm. The infrared beam passes alternately through two semicircular narrow bandpass filters. Absorption by the water vapor in the sample produces a 30-Hz modulation of the detector signal that is proportional to the water concentration. The maximum concentration that can be measured accurately is approximately 5%.

Burch, D. E.; Goodsell, D. S.

1981-09-01

218

Experimental evaluation of the drag coefficient of water rockets by a simple free-fall test  

NASA Astrophysics Data System (ADS)

The flight trajectory of a water rocket can be reasonably calculated if the magnitude of the drag coefficient is known. The experimental determination of this coefficient with enough precision is usually quite difficult, but in this paper we propose a simple free-fall experiment for undergraduate students to reasonably estimate the drag coefficient of water rockets made from plastic soft drink bottles. The experiment is performed using relatively small fall distances (only about 14 m) in addition with a simple digital-sound-recording device. The fall time is inferred from the recorded signal with quite good precision, and it is subsequently introduced as an input of a Matlab® program that estimates the magnitude of the drag coefficient. This procedure was tested first with a toy ball, obtaining a result with a deviation from the typical sphere value of only about 3%. For the particular water rocket used in the present investigation, a drag coefficient of 0.345 was estimated.

Barrio-Perotti, R.; Blanco-Marigorta, E.; Argüelles-Díaz, K.; Fernández-Oro, J.

2009-09-01

219

Physical and Water Absorption Characteristics of Some Improved Rice Varieties  

Microsoft Academic Search

The physical and water absorption characteristics of paddy and brown rice from some early maturing Oryza sativa varieties and newly developed interspecific (O. sativa × Oryza glaberrima) rice varieties were studied. The physical dimensions (length, breadth and width, length\\/width ratio, equivalent diameter),\\u000a grain surface area and volume, sphericity, 1,000-kernel weight, bulk and true densities as well as porosity were determined.

Taofik Akinyemi Shittu; M. B. Olaniyi; A. A. Oyekanmi; K. A. Okeleye

220

Influence of microcracking on water absorption and sorptivity of ECC  

Microsoft Academic Search

This paper presents the results of an experimental investigation on the water absorption and sorptivity properties of mechanically\\u000a loaded Engineered Cementitious Composites (ECC). ECC is a newly developed high performance fiber reinforced cementitious composite\\u000a with substantial benefit in both high ductility and improved durability due to tight crack width. By employing micromechanics-based\\u000a material design, ductility in excess of 3% under

Mustafa ?ahmaran; Victor C. Li

2009-01-01

221

Application of several activity coefficient models to water-organic-electrolyte aerosols of atmospheric interest  

Microsoft Academic Search

In this work, existing and modified activity coefficient models are examined in order to assess their capabilities to describe the properties of aqueous solution droplets relevant in the atmosphere. Five different water-organic-electrolyte activity coefficient models were first selected from the literature. Only one of these models included organics and electrolytes which are common in atmospheric aerosol particles. In the other

T. Raatikainen; A. Laaksonen

2005-01-01

222

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

ERIC Educational Resources Information Center

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

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

2009-01-01

223

Can the Lambert-Beer law be applied to the diffuse attenuation coefficient of ocean water?  

Microsoft Academic Search

Radiative transfer theory is combined with a bio-optical model of Case 1 waters and an optical model of the atmosphere to simulate the transport of radiation in the ocean-atmosphere system. The results are treated as experimental data to study the downwelling irradiance attenuation coefficient. It is shown that the downwelling irradiance attenuation coefficient just beneath the surface and the mean

HOWARD R. GORDON

1989-01-01

224

Estimation of Diffusion Coefficients for Electrolytes in Hot Water. Final Report.  

National Technical Information Service (NTIS)

Diffusion coefficients are calculated for electrolytes dissolved in water at temperatures 25 to 300 exp 0 C and saturation pressures. Plots and tables are given of estimated diffusion coefficients for NaCl at concentrations from infinite dilution to 4 mol...

W. T. Lindsay

1981-01-01

225

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

226

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

227

Phytoplankton light absorption and the package effect in California coastal waters  

Microsoft Academic Search

Phytoplankton absorption spectra were determined for communities collected in the upper euphotic zone over a 250 km transect across a highly variable region of the Southern California Bight. The influence of the 'package effect' on phytoplankton absorption spectra was assessed by com- parison of absorption coefficient spectra based on direct measurement with spectral reconstructions calculated from HPLC-determined pigment concentrations. Measurable

Norman B. Nelson; BB Prezelin; Robert R. Bidigare

1993-01-01

228

Temperature and Water Vapor Pressure Effects on the Friction Coefficient of Hydrogenated Diamondlike Carbon Films.  

National Technical Information Service (NTIS)

Microtribological measurements of a hydrogenated diamondlike carbon film in controlled gaseous environments show that water vapor plays a significant role in the friction coefficient. These experiments reveal an initial high friction transient behavior th...

A. Erdemir N. Argibay O. L. Eryilmaz P. L. Dickrell W. G. Sawyer

2009-01-01

229

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

EPA Science Inventory

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

230

The Streaming Potential Coupling Coefficient of Liquid Carbon Dioxide Injected Into Water Saturated Berea Sandstone  

Microsoft Academic Search

The streaming potential coupling coefficient was determined for a liquid carbon dioxide flood of a water-saturated sample of Berea sandstone. The coupling coefficient for the rock\\/water case was determined both before and after each CO2 flood of three samples using a low-pressure static head method. Next, liquid CO2 was allowed to flow through each sample. As the CO2 displaced the

J. R. Moore; S. D. Glaser; H. F. Morrison

2003-01-01

231

Calculation of air-water vapor mixtures thermal plasmas transport coefficients  

Microsoft Academic Search

Knowledge of transport coefficients of air-water vapor mixtures thermal plasmas is important to estimate the performances of electrical arc cutting in this gas by a circuit breaker. In this paper, air-water vapor mixtures thermal plasmas dynamical viscosity, thermal and electrical conductivities coefficients are calculated in a temperature range from 5000K to 30000K. The calculations are carried out by supposing local

A K Kagoné; Z Koalaga; F Zougmoré

2012-01-01

232

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

Microsoft Academic Search

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

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

1996-01-01

233

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

SciTech Connect

Diffusion coefficients are calculated for electrolytes dissolved in water at temperatures 25 to 300/sup 0/C and saturation pressures. Plots and tables are given of estimated diffusion coefficients for NaCl at concentrations from infinite dilution to 4 molal, limiting diffusion coefficients for divalent metal chlorides and for sodium phosphates of several compositions, and tracer diffusion coefficients for hydrochloric acid in sodium chloride solutions up to 4 molal. These data are useful for analysis of mass transport processes, such as concentration, corrosion, deposition, dissolution, dilution and neutralization, that can occur in nuclear steam generators and other power station apparatus.

Lindsay, W.T. Jr.

1981-08-01

234

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

235

Analysis of microscopic pore structures of rocks before and after water absorption  

Microsoft Academic Search

Hydrophilic characteristics of rocks are affected by their microscopic pore structures, which clearly change after water absorption. Water absorption tests and scanning electron microscopic (SEM) experiments on rock samples, located at a site in Tibet, China, were carried out. Changes of rock pore structures before and after water absorption were studied with the distribution of pore sizes and fractal characteristics

Li Dejian; Wang Guilian; Han Liqiang; Liu Peiyu; He Manchao; Yang Guoxing; Tai Qimin; Chen Cheng

2011-01-01

236

Transporters involved in glucose and water absorption in the Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) anterior midgut  

Microsoft Academic Search

Little is known about insect intestinal sugar absorption, in spite of the recent findings, and even less has been published regarding water absorption. The aim of this study was to shed light on putative transporters of water and glucose in the insect midgut. Glucose and water absorptions by the anterior ventriculus of Dysdercus peruvianus midgut were determined by feeding the

Thaís D. Bifano; Thiago G. P. Alegria; Walter R. Terra

2010-01-01

237

Mobile monitoring of particle light absorption coefficient in an urban area as a basis for land use regression.  

PubMed

Land use regression (LUR) is used to map spatial variability in air pollutant concentrations for risk assessment epidemiology, and air quality management. Conventional LUR requires long-term measurements at multiple locations, so application to particulate matter has been limited. Here we use mobile monitoring to characterize spatial variability in black carbon concentrations for LUR modeling. A particle soot absorption photometer in a moving vehicle was used to measure the absorption coefficient (sigma(ap)) during summertime periods of peak afternoon traffic at 39 locations. LUR was used to model the mean and 25th, 50th, 75th, and 90th percentile values of the distribution of 10 s measurements at each location. Model performance (measured by R2) was higher for the 25th and 50th percentiles (0.72 and 0.68, respectively) than for the mean, 75th and 90th percentiles (0.51, 0.55, and 0.54, respectively). Performance was similar to that reported for conventional LUR models of NO2 and NO in this region (116 sites) and better than that for mean sigma(ap) from fixed-location samplers (25 sites). Models of the mean, 75th, and 90th percentiles favored predictors describing truck, rather than total, traffic. This approach is applicable to other urban areas to facilitate the development of LUR models for particulate matter. PMID:19673250

Larson, Timothy; Henderson, Sarah B; Brauer, Michael

2009-07-01

238

Sticking coefficient and processing of water vapor on organic-coated nanoaerosols.  

PubMed

Organic-based aerosols may play an unexpectedly important role in the atmospheric processing of water vapor. In this paper, we report results of a molecular dynamics (MD) study on the sticking coefficient of water vapor on a coated particle (water droplet coated with fatty acid of radius approximately 4 nm). The sticking coefficient was found to be almost a constant (11-16%) for incident speeds around the most probable speed as opposed to 100% for water vapor incident on a pure water droplet. The sticking coefficient was found to increase with the size of the water cluster (water-Nmer) impinging the surface of the particle and was seen to approach 1 for impinging water clusters consisting of 10 molecules or more. We also computed the average energy transferred per collision for monomers impinging the surface of the coated particle and found the value to be 4.4581 kJ/mol. Most important perhaps was the fact that despite the lower sticking coefficient, the equilibrium vapor pressure of water over these inverted micelles was considerably lower due to the surface tension effects of the fatty acid layer. As such, these coated particles act as effective substrates for water vapor condensation and may play a role as cloud condensation nuclei. PMID:18193845

Chakraborty, Purnendu; Zachariah, Michael R

2008-01-15

239

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

240

Direct Octanol Water Partition Coefficient Determination Using Co-Current Chromatography  

Microsoft Academic Search

Octanol-water partition coefficients. Koct, can be measured directly using countercurrent chromatography (CCC) with an octanol-water biphasic solvent system. The mobile phase is water saturated with octanol, and the stationary phase is octanol saturated with water. The measurable Koct range was 0.003 to 300. A liquid stationary octanol phase permits the development of a dual-mode elution method using CCC which extends

Alain Berthod; Randy A. Menges; Daniel W. Armstrong

1992-01-01

241

What Is the Correct Value for the Brain-Blood Partition Coefficient for Water?  

Microsoft Academic Search

Summary: A knowledge of the brain-blood partition coefficient (?) for water is usually required for the measurement of CBF with [15O]water. The currently accepted value for whole-brain ?, 0.95-0.96 ml\\/g, calculated from brain and blood water content data, is incorrect because in the calculation, the blood water content was not adjusted for the density of blood. The correct value is

Peter Herscovitch; Marcus E. Raichle

1985-01-01

242

Determination of octanol-water partition coefficients using gradient liquid chromatography  

Microsoft Academic Search

The use of liquid chromatography to estimate octanol-water partition coefficients, log Kow, has been demonstrated. The capacity factor with a mobile phase of 100% water, kw, has been found to be a useful Chromatographic parameter. Values of Kw were derived from a computer software package (Hipac-G), designed for optimization and simulation of gradient LC systems. The chromatographic parameter, Kw, correlates

V. Makovskaya; J. R. Dean; W. R. Tomlinson; S. M. Hitchen; M. Comber

1995-01-01

243

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

244

Extended Octanol-Water Partition Coefficient Determination by Dual-Mode Centrifugal Partition Chromatography  

Microsoft Academic Search

The range of determination of octanol-water partition coefficients by CPC has been extended by the dual-mode approach. In this mode, the analyte was pumped in the descending mode with water as the mobile phase for a predetermined time. The mode was then switched to ascending with octanol as the mobile phase. Lipophilic materials only moved partially through the system in

S. J. Gluck; E. J. Martin

1990-01-01

245

Evaluation of water and sucrose diffusion coefficients in potato tissue during osmotic concentration  

Microsoft Academic Search

The water and sucrose effective diffusion coefficients behavior were studied in potato tubers immersed in aqueous sucrose solution, 50% (w\\/w), at 27 °C. Water and sucrose concentration profiles were measured as function of the position for 3, 6 and 12 h of immersion. These were adjusted to a mathematical model for three components that take into account the bulk flow

Maria Aparecida Mauro; Florencia Cecilia Menegalli

2003-01-01

246

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

247

Fugacity coefficients for free radicals in dense fluids: HO{sub 2} in supercritical water  

SciTech Connect

Water at elevated temperatures and pressures in attracting interest as a reaction medium and an environmentally benign alternative to organic solvents. The fugacity coefficients of the hydroperoxyl radical in supercritical water are estimated through molecular simulations. A potential function for the radical is first derived from ab initio self-consistent field molecular orbital calculations at the unrestricted Hartree-Fock level and from data in the literature. Molecular dynamics simulations of the hydroperoxyl radical are then performed in supercritical water and the fugacity coefficient of the radical is calculated by the free-energy perturbation method using the dynamic coupling parameter window-modification technique. The values of the fugacity coefficients at 773 K differ from unity. This methodology facilitates the incorporation of thermodynamic nonidealities in mechanism-based kinetic models for free-radical reactions in supercritical water.

Mizan, T.I.; Savage, P.E.; Ziff, R.M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering

1997-05-01

248

On-line atomization of selenium hydride in graphite furnaces: estimate of atomic absorption coefficient and spectroscopic temperature  

NASA Astrophysics Data System (ADS)

A transversely heated graphite tube atomizer (THGA) has been employed to ensure constant temperature within the observation volume. A method of sampling of gaseous selenium hydride from a container has been developed including a relation between observed peak area (integrated absorbance) and selenium mass injected into the furnace. This makes it possible to control fully the composition of the atomizer atmosphere. A boron nitride tube sealed to the injection hole of the graphite tube has been used as the interface. It performed well even at the highest tested atomization temperature (2400°C). Spectroscopic temperature measurements based on atomic absorption at the 196.1 nm and 204.0 nm Se lines have been used to determine the influence of carrier gas flow rates on the effective gas phase temperature in the atomizer at set furnace temperatures of 1800°C and 2200°C. Characteristic masses m0 at the 196.1 nm line, in pure argon atmosphere, have been determined at these set furnace temperatures for various argon gas flow rates. The data are employed to estimate an experimental value of the atomic absorption coefficient: (17.1 ± 0.8) × 10 -18 m 2. The value does not significantly differ from the theoretical value. m0 values found for the temperature range 1800-2400°C for the hydride injection into the furnace at the minimum feasible carrier gas flow rate are compared with characteristic masses for the traditional liquid sampling to the furnace in the same temperature range. This made it possible to estimate that the analyte losses through the injection port in the case of the traditional liquid sampling to the furnace are in the range 20-25%.

D?dina, Ji?í; Matoušek, Tomáš; Frech, Wolfgang

1996-07-01

249

Headspace gas chromatography for measurement of infinite dilution activity coefficients of C 4 alcohols in water  

Microsoft Academic Search

For environmental and other reasons, there is interest in determining values of infinite dilution activity coefficients (??) of organic solutes in volatile solvents, particularly in water. Here, we present a detailed description of a headspace gas chromatograph recently constructed for the measurement of infinite dilution activity coefficients and report values of ?? for 1-butanol, 2-butanol, 2-methyl-1-propanol (iso-butanol) and 2-methyl-2-propanol (tert-butanol)

Paul G Whitehead; Stanley I Sandler

1999-01-01

250

Effect of passive water absorption on transepithelial movement of extracellular solutes in rat intestine  

Microsoft Academic Search

Effect of passive water absorption on transepithelial movement of extracellular solutes in rat intestine. It was shown previously that intravenous infusion of saline solution decreases net absorption of sodium and water by rat small intestine and that there is an associated increased movement of inulin from blood into intestinal lumen. It was proposed that decreased absorption may be due to

Meyer D Lifschitz; Jorge A Garcia; Laurence E Earley

1973-01-01

251

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

252

ClogP(alk): a method for predicting alkane/water partition coefficient.  

PubMed

Alkane/water partition coefficients (P(alk)) are less familiar to the molecular design community than their 1-octanol/water equivalents and access to both data and prediction tools is much more limited. A method for predicting alkane/water partition coefficient from molecular structure is introduced. The basis for the ClogP(alk) model is the strong (R² = 0.987) relationship between alkane/water partition coefficient and molecular surface area (MSA) that was observed for saturated hydrocarbons. The model treats a molecule as a perturbation of a saturated hydrocarbon molecule with the same MSA and uses increments defined for functional groups to quantify the extent to which logP(alk) is perturbed by the introduction each functional group. Interactions between functional groups, such as intramolecular hydrogen bonds are also parameterized within a perturbation framework. The functional groups and interactions between them are specified substructurally in a transparent and reproducible manner using SMARTS notation. The ClogP(alk) model was parameterized using data measured for structurally prototypical compounds that dominate the literature on alkane/water partition coefficients and then validated using an external test set of 100 alkane/water logP measurements, the majority of which were for drugs. PMID:23737238

Kenny, Peter W; Montanari, Carlos A; Prokopczyk, Igor M

2013-06-05

253

Temperature dependence of infinite dilution activity coefficients in octanol and octanol/water partition coefficients of some volatile halogenated organic compounds  

SciTech Connect

The study of the fate and transport of volatile halogenated organic compounds in the environment is of interest as these chemicals, many of which have been classified as pollutants, are widely used as industrial solvents and are now appearing in water supplies. Infinite dilution activity coefficients and Henry`s law coefficients have been measured for 11 halogenated C{sub 1} to C{sub 3} compounds in 1-octanol above room temperature using a gas-liquid chromatographic measurement method. Then, using their earlier data for these substances in water and a correlation relating the limiting activity coefficients of a substance in pure water and in pure 1-octanol to their octanol/water partition coefficients, these latter quantities have been computed. One conclusion from these measurements is that the limiting activity coefficients in octanol and the octanol/water partition coefficients of the halogenated compounds studied are only weakly dependent on temperature over the range from 25 to 50 C. Also, from these and their earlier data, have estimated the infinite dilution partial molar excess enthalpies and excess entropies of these compounds in both 1-octanol and water.

Bhatai, S.R.; Sandler, S.I. [Univ. of Delaware, Newark, DE (United States)

1995-11-01

254

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

PubMed Central

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

Shang, Songhao

2012-01-01

255

Natural variability of phytoplanktonic absorption in oceanic waters: Influence of the size structure of algal populations  

NASA Astrophysics Data System (ADS)

The spectral absorption coefficients of phytoplankton in oceanic waters were previously shown to vary with chlorophyll a concentration according to nonlinear relationships with a great deal of noise. We analyzed this biological noise on a data set of 596 simultaneous absorption and high-pressure liquid chromatography (HPLC) pigment measurements acquired within the surface layer (first optical depth) from various regions of the world's oceans. We observed systematic deviations from the average relationships for some oceanic areas and also seasonally within given areas. Using the detailed HPLC measurements, the influences of pigment composition and package effect (the two main sources of variability in algal absorption for a given chlorophyll a concentration) were explicitly separated for each sample. It was found that while the pigment composition experiences large variations, even within a restricted chlorophyll range, it is often not (at least within the first optical depth) the dominant source of the biological noise. Instead, these deviations mostly result from variability in the pigment packaging effect (for a given chlorophyll a concentration) due to variations in algal community size structure. This conclusion is fully confirmed by an independent approach, which consists of estimating a "size index" of algal populations from the relative concentrations of taxonomic pigments.

Bricaud, Annick; Claustre, Hervé; Ras, JoséPhine; Oubelkheir, Kadija

2004-11-01

256

Spectral particle absorption coefficients, single scattering albedos and imaginary parts of refractive indices from ground based in situ measurements at Cape Verde Island during SAMUM-2  

NASA Astrophysics Data System (ADS)

During the SAMUM-2 experiment, spectral absorption coefficients, single scattering albedos and imaginary parts of refractive indices of mineral dust particles were investigated at the Cape Verde Islands. Main absorbing constituents of airborne samples were mineral dust and soot. PM10 spectral absorption coefficients were measured using a Spectral Optical Absorption Photometer (SOAP) covering the wavelength range from 300 to 960 nm with a resolution of 25 nm. From SOAP, also information on the particle scattering coefficients could be retrieved. Spectral single scattering albedos were obtained in the wavelength range from 350 to 960 nm. Imaginary parts of the refractive index were inferred from measured particle number size distributions and absorption coefficients using Mie scattering theory. Imaginary parts for a dust case were 0.012, 0.0047 and 0.0019 at the wavelengths 450, 550 and 950 nm, respectively, and the single scattering albedos were 0.91, 0.96 and 0.98 at the same wavelengths. During a marine case, the imaginary parts of the refractive indices were 0.0045, 0.0040 and 0.0036 and single scattering albedos were 0.93, 0.95 and 0.96 at the wavelengths given above.

Müller, T.; Schladitz, A.; Kandler, K.; Wiedensohler, A.

2011-09-01

257

Linear and nonlinear optical absorption coefficients and refractive index changes in spherical quantum dots: Effects of impurities, electric field, size, and optical intensity  

Microsoft Academic Search

In the present work, the case of a spherical quantum dot with parabolic confinement subjected to an external electric field with the presence of an impurity, the linear and third-order nonlinear optical absorption coefficients as well as refractive index changes have been calculated. The numerical method we are using for the calculation of the energy levels and the corresponding wave

Sotirios Baskoutas

2008-01-01

258

Using spectral information from the NIR water absorption features for the retrieval of canopy water content  

NASA Astrophysics Data System (ADS)

Canopy water content (CWC) is important for mapping and monitoring the condition of the terrestrial ecosystem. Spectral information related to the water absorption features at 970 nm and 1200 nm offers possibilities for deriving information on CWC. In this study, we compare the use of derivative spectra, spectral indices and continuum removal techniques for these regions. Hyperspectral reflectance data representing a range of canopies were simulated using the combined PROSPECT + SAILH model. Best results in estimating CWC were obtained by using spectral derivatives at the slopes of the 970 nm and 1200 nm water absorption features. Real data from two different test sites were analysed. Spectral information at both test sites was obtained with an ASD FieldSpec spectrometer, whereas at the second site HyMap airborne imaging spectrometer data were also acquired. Best results were obtained for the derivative spectra. In order to avoid the potential influence of atmospheric water vapour absorption bands the derivative of the reflectance on the right slope of the canopy water absorption feature at 970 nm can best be used for estimating CWC.

Clevers, J. G. P. W.; Kooistra, L.; Schaepman, M. E.

2008-09-01

259

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

NASA Astrophysics Data System (ADS)

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

Wang, Rui; Wei, Jingsong

2013-06-01

260

Defect-induced enhancement of absorption coefficient and electroabsorption properties in GaN/AlGaN centered defect quantum box (CDQB) nanocrystal  

NASA Astrophysics Data System (ADS)

In this paper, effect of an introduced cubic defect on electrical and optical properties of cubic quantum dot is studied. Self-consistent solution of the Schrödinger Poisson equations for evaluation of the proposed complex quantum dot is used. Optical properties (absorption and electroabsorption properties associated with intersublevel transition) of the proposed structure are also investigated using density matrix method. Effects of defect size on energy levels, carrier density, matrix element and optical linear absorption coefficient of centered defect quantum box (CDQB) are examined. It is shown that with increasing the defect size a considerable enhancement in magnitude of the absorption coefficient and also red-shift in resonance frequency are achievable. We show that the CDQB has higher absorption peak (at least 80 times) and tunable absorption spectra, due to increase of the matrix element and modified energy sublevels, compared quantum box structure without defect. Also, it is shown that the defect enhances electroabsorption properties (modulation bandwidth and the maximum variation of absorption peak with external field) of the quantum box structure.

Rostami, A.; Rasooli Saghai, H.; Baghban Asghari Nejad, H.

2008-08-01

261

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

262

An upper limit for water dimer absorption in the 750 nm spectral region and a revised water line list  

Microsoft Academic Search

Absorption of solar radiation by water dimer molecules in the Earth's atmosphere has the potential to act as a positive feedback effect for climate change. There seems little doubt from the results of previous laboratory and theoretical studies that significant concentrations of the water dimer should be present in the atmosphere, yet attempts to detect water dimer absorption signatures in

A. J. L. Shillings; S. M. Ball; M. J. Barber; J. Tennyson; R. L. Jones

2011-01-01

263

A upper limit for water dimer absorption in the 750 nm spectral region and a revised water line list  

Microsoft Academic Search

The absorption of solar radiation by water dimer molecules in the Earth's atmosphere can potentially act as a positive feedback effect for climate change. There seems little doubt from the results of previous laboratory and theoretical studies that significant concentrations of the water dimer should be present in the atmosphere, yet attempts to detect water dimer absorption signatures in atmospheric

A. J. L. Shillings; S. M. Ball; M. J. Barber; J. Tennyson; R. L. Jones

2010-01-01

264

Water absorption length measurement with the ANTARES optical beacon system  

NASA Astrophysics Data System (ADS)

ANTARES is a neutrino telescope located in the Mediterranean Sea with the aim of detecting high energy neutrinos of extra-terrestrial origin. It consists of a three dimensional array on 12 detection lines of photomultiplier tubes (PMTs) able to detect the Cherenkov light induced by muons produced in the interaction of neutrinos with the surrounding water and seabed. To reach the best angular resolution, good time and positioning calibrations are required. The propagation of Cherenkov photons strongly depends on the optical properties of the sea water, which has an impact on the reconstruction efficiency. The determination of the optical parameters, as the absorption and scattering lengths, is crucial to calculate properly the effective area and the angular resolution of the detector. The ANTARES optical beacon system consists of pulsed and fast, well controlled light sources distributed throughout the detector to carry out in situ the relative time calibration of the detector components. In this contribution we show some results on the sea water optical properties and their stability measured with the optical beacon system.

Yepes-Ramirez, Harold; ANTARES Collaboration

2011-01-01

265

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

2013-08-23

266

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

SciTech Connect

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

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

2009-07-01

267

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

Microsoft Academic Search

Measurements of near-infrared water vapour continuum using continuous wave cavity ring down spectroscopy (cw-CRDS) have been performed at around 10611.6 and 10685.2cm-1. The continuum absorption coefficients for N2-broadening have been determined to be CF296K=(1.0±0.2)×10-24cm2mol-1atm-1 and CF278K=(1.8±0.4)×10-24cm2mol-1atm-1 at 10611.6cm-1, and CF296K=(1.6±0.5)×10-24cm2mol-1atm-1 and CF278K=(2.1±0.4)×10-24cm2mol-1atm-1 at 10685.2cm-1, respectively.These results represent the first near-IR continuum laboratory data determined within the complex spectral environment in

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

2007-01-01

268

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

Microsoft Academic Search

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

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

2007-01-01

269

Isotope effects in water. Tracer diffusion coefficients for H/sub 2/ /sup 18/O in ordinary water  

SciTech Connect

A method is described for measuring the tracer diffusion coefficient of H/sub 2/ /sup 18/O in ordinary water. The method combines the conventional diaphragm cell technique with isotope ratio mass-spectrometric determination of tracer concentrations and gives diffusion coefficients of very high precision. The accuracy of the method is limited only by the accuracy of calibration of diaphragm cells and is such that the isotope effect for water diffusion has been measured precisely. Results are presented for temperatures from 278 to 323 K at 0.1 MPa, and for pressures up to 262.5 MPa at 323 K.

Easteal, A.J.; Edge, A.V.J.; Woolf, L.A.

1984-11-22

270

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

Microsoft Academic Search

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

Alain Berthod; Yoon Il Han; Daniel W. Armstrong

1988-01-01

271

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

Microsoft Academic Search

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

Elmira Arab Tehrany; Frantz Fournier; Stéphane Desobry

2004-01-01

272

Physicochemical interpretation and prediction of the dimyristoyl phosphatidyl choline–water partition coefficient  

Microsoft Academic Search

The dimyristoyl phosphatidyl choline (DMPC)–water partition coefficient (logKDMPC–W) has been proposed as an alternative to the 1-octanol–water system (logKOW) for describing molecular hydrophobicity. In this study literature values of logKDMPC–W for 49 compounds were collated. Quantitative structure–activity relationships (QSARs) were developed for logKDMPC–W in an attempt to develop a predictive model for its estimation and to investigate its meaning. Despite

Hiren Patel; T. Wayne Schultz; Mark T. D Cronin

2002-01-01

273

Partition coefficients of some aromatic hydrocarbons and ketones in water, blood and oil  

Microsoft Academic Search

Water\\/air, blood\\/air, oil\\/air, oil\\/water, and oil\\/blood partition (or solubility) coefficients of 17 aromatic hydrocarbons and ketones were measured by a newly developed vial-equilibration method, which needs no direct measurements of the concentration either in the liquid or in the air phase, but only the gas chromatographic peak heights of the air in the sample (in which a test material is

A Sato; T Nakajima

1979-01-01

274

Fuel-temperature coefficient for boiling water reactor transient calculations: Its dependence on reactor conditions  

SciTech Connect

For certain reactivity insertion accidents, the fuel-temperature coefficient (FTC) determines the major component of the feedback reactivity, which limits the peak fuel enthalpy during the transient. Some contributions to the FTC from the two energy groups typically used for boiling water reactor transient analysis and the dependence of the contributions on exposure and coolant void content are discussed.

Kallfelz, J.M.; Belblidia, L.A.; Grimm, P. [Paul Scherrer Inst., Villigen (Switzerland)

1995-10-01

275

Noise analysis method for monitoring the moderator temperature coefficient of pressurized water reactors. 1; Theory  

Microsoft Academic Search

In this paper a method is described for monitoring the moderator temperature coefficient of reactivity of pressurized water reactors based on the correlation of fluctuations in in-core neutron detector and core-exit thermocouple signals. The theoretical basis of the method is explained.

J. R. Jr. Thomas; J. D. Herr; D. S. Wood

1991-01-01

276

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...

277

Influence of averaging coefficients on weakly nonlinear stability of shallow water flows  

Microsoft Academic Search

Stability of shallow flows is analyzed in the present paper. Momentum correction coefficients are introduced in the shallow water equations in order to take into account non-uniformity of the velocity distribution in the vertical direction. Linear stability of parallel base flow is governed by the modified Rayleigh equation. Methods of weakly nonlinear theory are used in order to derive the

A. A. KOLYSHKIN; S. NAZAROVS

278

ACE Guided-Transformation Method for Estimation of the Coefficient of Soil-Water Diffusivity  

Microsoft Academic Search

Data-analytic tools for choosing transformations to increase linear association are applied to a basic problem of soil physics, the determination of the coefficient of soil-water diffusivity D(?). Data on Manawatu sandy loam illustrate the decisions the analyst must face and the quality of the estimates that the analyst can expect.

Richard D. De Veaux; J. Michael Steele

1989-01-01

279

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 ...

280

Heat Transfer Coefficients for Two-Phase (Water/Air) Flow Over a Tube Bank.  

National Technical Information Service (NTIS)

Local heat and mass transfer coefficients for spray flow over a heated tube bank were determined for a range of mass flux ratios and spray-water injection temperatures. Reynolds numbers were based on the minimum flow area within the tube bank and the tube...

R. A. Carpenter

1972-01-01

281

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

Microsoft Academic Search

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

Leland Marple; Bernard Berridge; Lewis Throop

1986-01-01

282

The absorption and reradiation of radio waves by oxygen and water vapor in the atmosphere  

Microsoft Academic Search

Pertinent data concerning the influence of atmospheric gases on the absorption of microwaves are reviewed. The restrictions placed on transmission at extremely high frequencies (above 15 GHz) through the atmosphere by absorption and reradiation by oxygen and water vapor, and absorption and scattering by raindrops are pointed out. The characteristics of the regions of lesser attenuation (windows) at 35, 90,

A. W. Straiton

1975-01-01

283

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

NASA Astrophysics Data System (ADS)

We report on the measurement of diffusion (D), thermodiffusion (DT), and Soret (ST) 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 ST at low water concentrations.

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

2012-06-01

284

Limiting interdiffusion coefficients of Tris(acetylacetonato)cobalt(III) in water and in organic solvents  

Microsoft Academic Search

The diffusion coefficients of tris(acetylacetonato)-cobalt(III) in water (5, 15, 25, and 40°C), methanol (25°C), ethanol (15, 25, and 45°C), 1-propanol (25°C), 1-butanol (45°C), acetone (25 and 40°C), 2-butanone (25°C), acetonitrile (25°C), tetrahydrofuran (25°C), benzen (25°C), toluene (25°C), and carbon tetrachloride (25°C) have been measured at concentrations close to infinite dilution. The Stokes-Einstein coefficient (f=kT\\/Dp?r) has been calculated for Co(acac)3 in

Toshihiro Tominaga; Kiyotaka Tanabe; Jun-ichi Takanaka

1984-01-01

285

The partition coefficients of ethane between vapor and hydrate phase for methane + ethane + water and methane + ethane + THF + water systems  

Microsoft Academic Search

The vapor–hydrate equilibria were measured firstly for CH4 + C2H6 + water system beyond incipient conditions and the results showed that the partition coefficients of ethane between vapor and hydrate phase were not promising. And then the gas–hydrate equilibria were studied experimentally in detail for CH4 + C2H6 + tetrahydrofuran (THF) + water systems in the temperature range of 274.15–282.15K,

L.-W. Zhang; G.-J. Chen; X.-Q. Guo; C.-Y. Sun; L.-Y. Yang

2004-01-01

286

Amount of leachant and water absorption levels of wood treated with borates and water repellents.  

PubMed

Wood protection efficacy of borates against biological agents, flame retardancy, and suitability to the environment is well known. Since borates can be applied to timber as water based solutions, they are preferred economically as well. Even though they are highly mobile in wood, boron compounds are widely used in timber preservation. Borates migrate in liquid and increase the hygroscopicity of wood in damp conditions. This study deals with the physical restriction of water access in wood by impregnating water repellent agents into wood to limit amount of leachant and water absorption levels of wood after boron treatment. Borates were incorporated with polyethylene glycol-400 (PEG-400) their bulking effect in wood was considered. Results indicated that the amount of leachates from wood treated with borates in PEG-400 was remarkably higher compared to those of wood treated with the aqueous solutions of borates. Water absorption (WA) levels of wood treated with aqueous solutions of borates were higher than those of their treated samples with the solutions in PEG-400. Secondary treatments of wood with the water repellent (WR) chemicals following borate impregnation reduced the leaching of chemicals from wood in water and also WA of the specimens were less than those of the wood treated with only borates from aqueous and PEG solutions. Styrene (St) was the most effective monomer among the other agents used in terms of immobility effect on borates and WA. PMID:16359861

Baysal, Ergun; Sonmez, Abdullah; Colak, Mehmet; Toker, Hilmi

2005-12-15

287

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

288

Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400-750 nm spectral range  

Microsoft Academic Search

The temperature and salt dependencies of absorption by liquid water (H2O) and heavy water (D2O) were determined using a hyperspectral absorption and attenuation meter (WET Labs, AC-S). Sodium chloride (NaCl) was used as a proxy for seawater salts. There was no significant temperature (PsiT) or salt (PsiS) dependency of absorption at wavelengths 550 nm, PsiT exhibited peaks at ˜604, 662,

James M. Sullivan; Michael S. Twardowski; J. Ronald V. Zaneveld; Casey M. Moore; Andrew H. Barnard; Percy L. Donaghay; Bruce Rhoades

2006-01-01

289

Combination of COSMOmic and molecular dynamics simulations for the calculation of membrane-water partition coefficients.  

PubMed

The importance of membrane-water partition coefficients led to the recent extension of the conductor-like screening model for realistic solvation (COSMO-RS) to micelles and biomembranes termed COSMOmic. Compared to COSMO-RS, this new approach needs structural information to account for the anisotropy of colloidal systems. This information can be obtained from molecular dynamics (MD) simulations. In this work, we show that this combination of molecular methods can efficiently be used to predict partition coefficients with good agreement to experimental data and enables screening studies. However, there is a discrepancy between the amount of data generated by MD simulations and the structural information needed for COSMOmic. Therefore, a new scheme is presented to extract data from MD trajectories for COSMOmic calculations. In particular, we show how to calculate the system structure from MD, the influence of lipid conformers, the relation to the COSMOmic layer size, and the water/lipid ratio impact. For a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayer, 66 partition coefficients for various solutes were calculated. Further, 52 partition coefficients for a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer system were calculated. All these calculations were compared to experimental data. PMID:23447371

Jakobtorweihen, Sven; Ingram, Thomas; Smirnova, Irina

2013-02-28

290

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

Microsoft Academic Search

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

SERAPHIN A. SULLIVAN

1963-01-01

291

The Influence of Laminated Leather Structure on the Water Vapour Absorption and Desorption Behaviour  

Microsoft Academic Search

In this paper the experimental and theoretical investigations of moisture transfer through microporous film laminated leather are presented. The water vapour absorption and desorption processes of laminated leather are described. Water vapour absorption in the laminated leather and its separate layers may be classified as non-Fickian: sigmoidal - for microporous film and two-stage - for the leather of different structures.

Virginijus URBELIS

292

Water absorption by secondary organic aerosol and its effect on inorganic aerosol behavior  

Microsoft Academic Search

The hygroscopic nature of atmospheric aerosol has generally been associated with its inorganic fraction. In this study, a group contribution method is used to predict the water absorption of secondary organic aerosol (SOA). Compared against growth measurements of mixed inorganic-organic particles, this method appears to provide a first-order approximation in predicting SOA water absorption. The growth of common SOA species

Asif S. Ansari; Spyros N. Pandis

2000-01-01

293

Modeling, simulation and optimization of a solar collector driven water heating and absorption cooling plant  

Microsoft Academic Search

A cogeneration system consisting of a solar collector, a gas burner, a thermal storage reservoir, a hot water heat exchanger, and an absorption refrigerator is devised to simultaneously produce heating (hot water heat exchanger) and cooling (absorption refrigerator system). A simplified mathematical model, which combines fundamental and empirical correlations, and principles of classical thermodynamics, mass and heat transfer, is developed.

J. V. C. Vargas; J. C. Ordonez; E. Dilay; J. A. R. Parise

2009-01-01

294

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

National Technical Information Service (NTIS)

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 he...

D. L. Dietrich F. A. Williams M. C. Hicks V. Nayagam

2012-01-01

295

Effect of water absorption on the mechanical properties of hemp fibre reinforced unsaturated polyester composites  

Microsoft Academic Search

Hemp fibre reinforced unsaturated polyester composites (HFRUPE) were subjected to water immersion tests in order to study the effects of water absorption on the mechanical properties. HFRUPE composites specimens containing 0, 0.10, 0.15, 0.21 and 0.26 fibre volume fraction were prepared. Water absorption tests were conducted by immersing specimens in a de-ionised water bath at 25°C and 100°C for different

H. N. Dhakal; Z. Y. Zhang; M. O. W. Richardson

2007-01-01

296

Determination of an empirical law of aluminium and magnesium alloys absorption coefficient during Nd : YAG laser interaction  

Microsoft Academic Search

Welding laser modelling requires knowledge about relative changes of many thermo-physical parameters involved in the interaction. The absorptivity of the material is one of the most important. In this study, experimental measurements of absorptivity with an integrating sphere on two alloys (aluminium and magnesium) were made. These results were compared with an analytical calculation that takes into account the trapping

Nicolas Pierron; Pierre Sallamand; Jean-Marie Jouvard; Eugen Cicala; Simone Matteï

2007-01-01

297

Absorption  

PubMed Central

Given that mind–body interventions constitute a major portion of complementary and alternative medicine used by the public, it seems important to explore those human characteristics that may contribute to the efficacy of mind–body interventions in those who are most likely to benefit. One such characteristic, absorption, reflects an individual’s cognitive capacity for involvement in sensory and imaginative experiences in ways that alter an individual’s perception, memory, and mood with behavioral and biological consequences. Thus, one’s level of absorption may potentially create differential treatment effects in mind–body intervention outcomes. Conducting practical clinical trials helps address the challenge of determining whether a specific mind–body modality intervention may be effective. Such trials may be strengthened by including measures of personality dimensions such as absorption.

Menzies, Victoria; Taylor, Ann Gill; Bourguignon, Cheryl

2009-01-01

298

Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure  

NASA Astrophysics Data System (ADS)

A sub-10 nm, high-density, periodic silicon-nanodisc (Si-ND) array has been fabricated using a new top-down process, which involves a 2D array bio-template etching mask made of Listeria-Dps with a 4.5 nm diameter iron oxide core and damage-free neutral-beam etching (Si-ND diameter: 6.4 nm). An Si-ND array with an SiO2 matrix demonstrated more controllable optical bandgap energy due to the fine tunability of the Si-ND thickness and diameter. Unlike the case of shrinking Si-ND thickness, the case of shrinking Si-ND diameter simultaneously increased the optical absorption coefficient and the optical bandgap energy. The optical absorption coefficient became higher due to the decrease in the center-to-center distance of NDs to enhance wavefunction coupling. This means that our 6 nm diameter Si-ND structure can satisfy the strict requirements of optical bandgap energy control and high absorption coefficient for achieving realistic Si quantum dot solar cells.

Fairuz Budiman, Mohd; Hu, Weiguo; Igarashi, Makoto; Tsukamoto, Rikako; Isoda, Taiga; Itoh, Kohei M.; Yamashita, Ichiro; Murayama, Akihiro; Okada, Yoshitaka; Samukawa, Seiji

2012-02-01

299

Self-diffusion coefficient of water in Nafion-117 membrane with different monovalent counterions: a radiotracer study  

Microsoft Academic Search

The self-diffusion coefficient of water in Nafion-117 membrane in different cationic forms was measured by the transient radiotracer method, which is based on an analytical solution of Fick's second law. The self-diffusion coefficient of water in the membrane was obtained from the analysis of time-dependent isotopic-exchange rates of tritium tagged water between sample of Nafion-117 membrane and equilibrating water. This

G. Suresh; Y. M. Scindia; A. K. Pandey; A. Goswami

2005-01-01

300

Partition coefficients for alcohol tracers between nonaqueous-phase liquids and water from UNIFAC-solubility method  

Microsoft Academic Search

In this work, we have applied a group-contribution activity-coefficient model, UNIFAC, and the solubility of alcohols in water to estimate partition coefficients for alcohol tracers between water and nonaqueous-phase liquids (NAPLs). The effects of temperature and mutual solubility between NAPL and aqueous phases on the estimation of partition coefficients were also investigated. By comparing the estimated results with experimental partition

Peng Wang; Varadarajan Dwarakanath; Bruce A. Rouse; Gary A. Pope; Kamy Sepehrnoori

1998-01-01

301

Water and solute diffusion coefficients of carrot as a function of temperature and concentration during osmotic dehydration  

Microsoft Academic Search

Mass transfer was quantitatively investigated during osmotic dehydration of fresh carrot over a range of concentration (40–70 °B) and temperature (30–50 °C) of osmotic solution. Effective diffusion coefficients of water as well as sucrose were estimated using the solution of Fick's unsteady state law. Multilinear analysis of the estimated effective diffusion coefficients of water and solute revealed that these values

N. K. Rastogi; K. S. M. S. Raghavarao

1997-01-01

302

Prediction of bulk modulus and volumetric expansion coefficient of water for leak tightness test of pipelines  

Microsoft Academic Search

To determine whether any pressure variation in pipeline hydrostatic test is a result of temperature changes or the presence of leaks, the calculation of pressure\\/temperature changes is required for test sections. In these calculations, bulk modulus and volumetric expansion coefficient of fresh or sea water must be taken into account. In this study, a simple-to-use correlation is developed to predict

Alireza Bahadori; Hari B. Vuthaluru

2009-01-01

303

Aqueous solubility and octan-1-ol to water partition coefficients of aliphatic hydrocarbons  

Microsoft Academic Search

The aqueous solubility (S) and octanol-water partition coefficients (P) of homologous series of n-, 2-methyl-, and 3-methylalkanes, as well as 1-alkenes, have been determined by extrapolation of known results, direct measurement, and high-pressure liquid chromatography (HP-LC). Long-term equilibration experiments, used to reduce aggregate formation, indicated that n-dodecane and n-tetradecane have S values in agreement with those obtained by extrapolation of

Michael Coates; Des W. Connell; Diane M. Barron

1985-01-01

304

Hydraulic Conductivity, Immobile Water Content, and Exchange Coefficient in Three Soil Profiles  

Microsoft Academic Search

We used tension disk infiltrometers to determine the hydraulic con- ductivity at the matric potential of 20.1 kPa (K20.1), the immobile water fraction (uim\\/u), and the mass exchange coefficient (a) in three soil profiles of an agricultural field cropped with winter wheat (Triticum aestivum L.). A significant effect of soil horizonation was found for K20.1, uim\\/u, and a and could

L. Alletto; Y. Coquet; P. Vachier; C. Labat

2006-01-01

305

Determination of octanol–water partition coefficients of pesticides by microemulsion electrokinetic chromatography  

Microsoft Academic Search

Microemulsion electrokinetic chromatography (MEEKC) was evaluated as a screening tool for the indirect measurement of octanol–water partition coefficients (log Po\\/w) of pesticide compounds. Over 80 pesticide compounds representing a variety of structural characteristics were studied, and good correlation of log Po\\/w with the logarithm of the retention factor was found. The microemulsion system studied allowed the separation of compounds in

W. L. Klotz; M. R. Schure; J. P. Foley

2001-01-01

306

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

Microsoft Academic Search

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

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

2003-01-01

307

Computing partition coefficients for small organic molecules in the octanol\\/water system  

Microsoft Academic Search

Using a new analytical method to compute partial atomic van der Waals surface areas, the possibility to correlate partition coefficients to partial atomic surfaces was re-examined, for the octanol\\/water system. A satisfactoring correlation was obtained for a large set of small organic molecules, provided that and surface elements are introduced in addition to the traditional differentiation into polar and non-polar

M. Ulmschneider; E. Pénigault

1999-01-01

308

Rapid estimation of octanol–water partition coefficients using synthesized vesicles in electrokinetic chromatography  

Microsoft Academic Search

Vesicle electrokinetic chromatography (VEKC) using vesicles synthesized from the oppositely charged surfactants cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) and from the double-chained anionic surfactant bis(2-ethylhexyl)sodium sulfosuccinate (AOT) was applied to the indirect measurement of octanol–water partition coefficients (log Po\\/w). A variety of small organic molecules with varying functional groups, pesticides, and organic acids were evaluated by correlating log

W. L Klotz; M. R Schure; J. P Foley

2002-01-01

309

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

Microsoft Academic Search

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

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

1999-01-01

310

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

311

The change in the spectral reflectivity and integral absorption coefficient of TiO2 powders under the influence of simulated solar radiation  

NASA Astrophysics Data System (ADS)

Results are presented of experimental measurements of changes in the spectral reflectivity and integral absorption coefficient of pressed powders of the pigment TiO2, which is used in spacecraft reflective thermal protection coatings, under simulated solar irradiation. Specimens of the pressed TiO2 rutile powders were irradiated in a 10 to the -7th torr vacuum by a DKSR-3000 xenon lamp at an ultraviolet intensity 9.5 times that of the sun. The shape of the reflectance spectrum of TiO2 powder is observed to vary as a function of the amount of radiation received, with significant decreases in reflectivity in the visible and infrared regions. Corresponding increases in integral absorptivity are also observed as a function of exposure time, while exposure at atmospheric pressures inhibits the induced absorption in the infrared. Results are explained in terms of the photolysis of TiO2 by solar irradiation.

Mikhailov, M. M.; Dvoretskii, M. I.

312

QSPR modeling of octanol\\/water partition coefficient for vitamins by optimal descriptors calculated with SMILES  

Microsoft Academic Search

Simplified molecular input line entry system (SMILES) has been utilized in constructing quantitative structure–property relationships (QSPR) for octanol\\/water partition coefficient of vitamins and organic compounds of different classes by optimal descriptors. Statistical characteristics of the best model (vitamins) are the following: n=17, R2=0.9841, s=0.634, F=931 (training set); n=7, R2=0.9928, s=0.773, F=690 (test set). Using this approach for modeling octanol\\/water partition

A. A. Toropov; A. P. Toropova; I. Raska Jr.

2008-01-01

313

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

2008-08-12

314

Water diffusion coefficients of horizontal soil columns from natural saline-alkaline wetlands in a semiarid area  

NASA Astrophysics Data System (ADS)

Water diffusion coefficients of soils directly control the solute (such as nitrogen and phosphorous) movement in wetlands, which greatly influences the water quality of rivers. The processes of water diffusion in natural saline-alkaline wetland soils were simulated by using horizontal soil columns from the Erbaifangzi (EBFZ) wetland in the Xianghai National Natural Reserve of China in 2001. The results showed that the water diffusion coefficient was the lowest in the topsoil. It followed the order 0-10 cm < 10-20 cm < 20-60 cm. The water diffusion coefficients decreased exponentially with an increase in the distance but increased exponentially with increases in the volumetric soil water contents. The changing curve of the topsoil was steeper, and the water diffusion coefficients were closely linked with the soil properties such as the SOM and clay contents.

Bai, Junhong; Deng, Wei; Cui, Baoshan; Ouyang, Hua

2007-06-01

315

Influence of Soil Water Stress on Evaporation, Root Absorption, and Internal Water Status of Cotton 1  

PubMed Central

Diurnal variations in leaf water potential, diffusion resistance, relative water content, stem diameter, leaf temperature, and energy balance components were measured in cotton (Gossypium hirsutum L. var. Lankart 57) during drought stress under field conditions. A plot of leaf water potential against either relative water content or stem diameter during the 24-hour period yielded a closed hysteresis loop. The relation between cell hydration and evaporation is discussed. Despite low soil water potential in the main root zone, significant plant evaporation rates were maintained. Root absorption rates as a function of soil depth were calculated from water content profiles measured with a neutron probe. The maximal root absorption rate of 3.5 × 10?3 day?1 occurred at the 75-centimeter depth, well below the main root zone. Stomatal resistance of individual leaves during the daylight hours remained nearly constant at 2.5 seconds centimeter?1 even though leaf water potentials approached ?30 bars. A growth chamber study indicated stomatal closure occurred at potentials near ?16 bars. Possible implications of high soil water stress in relation to stomatal function and growth are discussed. Based on an energy balance method, the actual to potential plant evapotranspiration ratio was 0.43 for the 24-hour period, indicating partial stomatal closure. A surface resistance, rs, of 4.0 seconds centimeter?1 was calculated for the incomplete canopy with the use of the energy balance data. Alternatively, a canopy resistance of 1.3 seconds centimeter?1 was attained from a relationship between leaf area and stomatal resistance of individual leaves. If the soil resistance was assumed to be very large and the canopy resistance was weighted for the fractional ground cover of the crop, the calculated surface resistance was 4.3 seconds centimeter?1. Under these conditions, the two independent estimates of rs were in essential agreement.

Jordan, Wayne R.; Ritchie, Joe T.

1971-01-01

316

Determination of an empirical law of aluminium and magnesium alloys absorption coefficient during Nd : YAG laser interaction  

NASA Astrophysics Data System (ADS)

Welding laser modelling requires knowledge about relative changes of many thermo-physical parameters involved in the interaction. The absorptivity of the material is one of the most important. In this study, experimental measurements of absorptivity with an integrating sphere on two alloys (aluminium and magnesium) were made. These results were compared with an analytical calculation that takes into account the trapping of the beam by multiple reflections inside the keyhole. Based on a statistical method, an empirical law is proposed connecting absorptivity with the peak power of the laser and the duration of interaction. During the interaction, two distinct phenomenologies are brought to light. A threshold is then defined after which the physical process becomes stable. Below this threshold, the measurement of absorptivity is problematic, and the values are widely dispersed.

Pierron, Nicolas; Sallamand, Pierre; Jouvard, Jean-Marie; Cicala, Eugen; Matteï, Simone

2007-04-01

317

Quantitative spectroscopic determination of hemoglobin concentration and saturation in a turbid medium: analysis of the effect of water absorption  

NASA Astrophysics Data System (ADS)

The contribution of water to the quantitative determination of hemoglobin concentration and saturation by near-IR spectroscopy in turbid media was investigated. The study consisted of in vitro measurements of an aqueous suspension containing Liposyn, bovine blood, and yeast buffered at pH 7.2. The optical coefficients of the medium were similar to those of biological tissue n the near-infrared, and the hemoglobin concentration was about 23 (mu) M. It was possible to reversibly saturate and desaturate hemoglobin in the full range of 0 to 100 percent by flowing either oxygen or nitrogen through the suspension. In these experimental conditions, water absorption must be taken into account to obtain accurate oxyhemoglobin concentrations and low hemoglobin saturation values. By contrast, the water correction has a small effect on the determination of deoxyhemoglobin concentration and high hemoglobin saturation values. By extrapolating the result to physiological conditions, where water content is lower and hemoglobin content is higher than in the experimental conditions, it was concluded that water absorption should have a smaller effect on the determination of hemoglobin concentrations and saturation in tissues at the wavelengths used in this study. In particular, for hemoglobin concentrations larger than 100 (mu) M, the water correction is less than 5 percent at saturation values higher than 50 percent.

Franceschini, Maria A.; Fantini, Sergio; Cerussi, Albert E.; Barbieri, Beniamino F.; Chance, Britton; Gratton, Enrico

1997-04-01

318

Transport coefficients for electrons in water vapor: definition, measurement, and calculation.  

PubMed

Comparison of experimental and theoretical transport data for electron swarms in water vapour over a wide range of fields provides a rigorous test of (e(-), H(2)O) scattering cross sections over a correspondingly broad range of energies. That like should be compared with like is axiomatic, but the definition of transport coefficients at high fields, when non-conservative processes are significant, has long been contentious. This paper revisits and distills the most essential aspects of the definition and calculation of transport coefficients, giving numerical results for the drift velocity and ionisation coefficient of electrons in water vapour. In particular, the relationship between the theoretically calculated bulk drift velocities of [K. F. Ness and R. E. Robson, Phys. Rev. A 38, 1446 (1988)] and the experimental "arrival time spectra" drift velocity data of Hasegawa et al. [J. Phys. D 40(8), 2495 (2007)] is established. This enables the Hasegawa et al. data to be reconciliated with the previous literature, and facilitates selection of the best (e(-), H(2)O) cross section set. PMID:21322692

Robson, R E; White, R D; Ness, K F

2011-02-14

319

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

2009-07-14

320

Evaluation of capillary water absorption in rendering mortars made with powdered waterproofing additives  

Microsoft Academic Search

Several additives, such as powdered stearates, oleates, silanes and silicone films, are used to avoid water absorption in renders. This paper looks at the effectiveness of six powdered waterproofing additives after 28days of curing at: 0.00%, 0.25%, 0.50%, 1.00% and 2.00% w\\/w on the whole composition. The waterproofing efficiency is analyzed by capillary water absorption tests, while water immersion tests

Marcos Lanzón; P. A. García-Ruiz

2009-01-01

321

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

NASA Astrophysics Data System (ADS)

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

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

1993-03-01

322

MEASUREMENT OF THE ABSORPTION CHARACTERISTICS OF SUPERSATURATED WATER VAPOR  

Microsoft Academic Search

the atmosphere by as much as 40 Wm-2. This enhanced absorption, which was recognised by comparing model calculations with satellite-borne radiometric measurements, remains to be explained. Controversial explanations of this newly discovered fact have been offered and debated. A school of thought suggests that the enhanced absorption of the incoming short-wave solar radiation is due to erroneous depiction of the

Prasad Varanasi; B. Ranganayakamma; S. Mathur; T. Refaat; C. R. Prasad

323

Human biokinetics of strontium. Part I: intestinal absorption rate and its impact on the dose coefficient of 90Sr after ingestion.  

PubMed

Intestinal absorption of strontium (Sr) in thirteen healthy adult German volunteers has been investigated by simultaneous oral and intravenous administration of two stable tracer isotopes, i.e. (84)Sr and (86)Sr. The measured Sr tracer concentration in plasma was analyzed using the convolution integral technique to obtain the intestinal absorption rate. The results showed that the Sr labeled in different foodstuffs was absorbed into the body fluids in a large range of difference. The maximum Sr absorption rates were observed within 60-120 min after administration. The rate of absorption is used to evaluate the intestinal absorption fraction, i.e. the f (1) value for various foodstuffs. The equivalent and effective dose coefficients for ingestion of (90)Sr were calculated using these f (1) values, and they were compared with those recommended by the International Commission on Radiological Protection (ICRP). The geometric and arithmetic means of the f (1) values are 0.38 and 0.45 associated with a geometric standard deviation and a standard deviation of 1.88 and 0.22, respectively. The 90% confidence interval of the f (1) values obtained in the present study ranges from 0.13 to 0.98. Expressed as the ratio of the 95 and 50% percentiles of the estimated probability, the uncertainty for the f (1) value corresponds to a factor of 2.58. The effective dose coefficients of (90)Sr after ingestion are 6.1 x 10(-9) Sv Bq(-1) for an f(1) value of 0.05, 1.0 x 10(-8) Sv Bq(-1) for 0.1, 1.9 x 10(-8) Sv Bq(-1) for 0.2, 2.8 x 10(-8) Sv Bq(-1) for 0.3, 3.6 x 10(-8) Sv Bq(-1) for 0.4, 5.3 x 10(-8) Sv Bq(-1) for 0.6, 7.1 x 10(-8) Sv Bq(-1) for 0.8, and 7.9 x 10(-8) Sv Bq(-1) for 0.9, respectively. Taking the effective dose coefficient of 2.8 x 10(-8) Sv Bq(-1) for an f (1) value of 0.3, which is recommended by the ICRP, as a reference, the effective dose coefficient of (90)Sr after ingestion varies by a factor of 2.8 when the f (1) value changes by a factor of 3, i.e. it decreases from 0.3 to 0.1 or increases from 0.3 to 0.9, respectively. PMID:16733723

Li, Wei Bo; Höllriegl, Vera; Roth, Paul; Oeh, Uwe

2006-05-30

324

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.

Raatikainen, Tomi; Nenes, Athanasios; Seinfeld, John H.; Morales, Ricardo; Moore, Richard H.; Lathem, Terry L.; Lance, Sara; Padro, 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

325

Water and Water Vapor Penetration Through Coatings  

Microsoft Academic Search

Water and water vapor transport in two-layer systems where one layer acts as water retarder are analyzed. In the experimental work, four external paints supposed to protect the underlying structure against water under common service conditions are applied on glass fiber reinforced concrete substrates. The water absorption coefficient and the effective water vapor diffusion coefficient are chosen as evaluation parameters

Jitka Podêbradská; Jaroslava Drchalová

2002-01-01

326

Remarkable optical red shift and extremely high optical absorption coefficient of V-Ga co-doped TiO2  

NASA Astrophysics Data System (ADS)

A first attempt has been made to study the effect of codoping of transition metal and sp metal on the electronic structure and associated optical properties of TiO2, through V-Ga codoped thin films. V-Ga codoped rutile TiO2 films were fabricated on fused quartz substrates using pulsed laser ablation, followed by heat treatment at high temperatures. Gigantic redshift in the optical absorption edge was observed in V-Ga co-doped TiO2 materials, from UV to infrared region with high absorption coefficient. Through combined structural characterization and theoretical modeling, this is attributed to the p-d hybridization between the two metals. This leads to additional energy bands to overlap with the minimum of the conduction band, leading to remarkably narrowed band gap free of mid-gap states. The direct-gap of the co-doped phase is key to the remarkably high optical absorption coefficient of the coped titania.

Deng, Quanrong; Han, Xiaoping; Gao, Yun; Shao, Guosheng

2012-07-01

327

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

328

Investigation of stimulated Brillouin scattering media perfluoro-compound and perfluoropolyether with a low absorption coefficient and high power-load ability.  

PubMed

The correlations between stimulated Brillouin scattering (SBS) characteristics of perfluoro-compound (PFC) and perfluoropolyether (PFPE) and their chemical structure are analyzed in detail and a series of new PFC and PFPE are reported. In the Nd:YAG laser system, the absorption coefficient, optical breakdown threshold (OBT), SBS threshold, and Brillouin frequency shift of new media such as FC-87, FC-43, HT-55, and DET are measured. Parameters such as gain coefficient, Brillouin linewidth, and phonon lifetime are calculated. The results demonstrate their good SBS properties: the absorption coefficients are below 10(-3)cm(-1) and OBTs are above 100 GW/cm(2). These media also exhibit a series of unique physicochemical properties, i.e., high heat-resistance, high oxidation stability, good chemical inertness, and insulation properties. The discovery of new media not only diversifies SBS medium, but also improves the performance of the SBS system, thereby laying a good foundation for the application of a SBS phase conjugation mirror in a high-power laser system. PMID:18311273

Hasi, W L J; Lu, Z W; Gong, S; Liu, S J; Li, Q; He, W M

2008-03-01

329

Investigation of stimulated Brillouin scattering media perfluoro-compound and perfluoropolyether with a low absorption coefficient and high power-load ability  

NASA Astrophysics Data System (ADS)

The correlations between stimulated Brillouin scattering (SBS) characteristics of perfluoro-compound (PFC) and perfluoropolyether (PFPE) and their chemical structure are analyzed in detail and a series of new PFC and PFPE are reported. In the Nd:YAG laser system, the absorption coefficient, optical breakdown threshold (OBT), SBS threshold, and Brillouin frequency shift of new media such as FC-87, FC-43, HT-55, and DET are measured. Parameters such as gain coefficient, Brillouin linewidth, and phonon lifetime are calculated. The results demonstrate their good SBS properties: the absorption coefficients are below 10-3cm-1 and OBTs are above 100 GW/cm2. These media also exhibit a series of unique physicochemical properties, i.e., high heat-resistance, high oxidation stability, good chemical inertness, and insulation properties. The discovery of new media not only diversifies SBS medium, but also improves the performance of the SBS system, thereby laying a good foundation for the application of a SBS phase conjugation mirror in a high-power laser system.

Hasi, W. L. J.; Lu, Z. W.; Gong, S.; Liu, S. J.; Li, Q.; He, W. M.

2008-03-01

330

What is the correct value for the brain: blood partition coefficient for water  

SciTech Connect

A knowledge of the brain: blood partition coefficient (lambda) for water is usually required for the measurement of cerebral blood flow (CBF) with positron emission tomography (PET) and 0-15 labelled water. The correct calculation of this important parameter from the ratio of brain and blood water contents is reviewed, and the effect of physiological variations in these water contents on lambda is demonstrated. The currently accepted value for whole brain lambda is 0.95-0.96 ml/g, calculated from brain and blood water contents of 77g/100g and 80.5g/100g, respectively. However, this value for lambda is incorrect, because in the calculation the blood water content value was not adjusted for the density of blood. The correct value is 0.91 ml/g. Variations in brain or blood water content affect lambda. Over an hematocrit range of 25% to 55%, lambda varies from 0.86 to 0.93 ml/g, due to a decrease in blood water content. lambda changes with age, and varies regionally in the brain, as brain water content is inversely related to lipid and myelin content. The lambda of the human newborn brain, 1.10 ml/g, is considerably higher than in the adult. Differences in lambda between gray and white matter are well known. However, because of variations in water content, the lambda's of thalamus (0.88 ml/g) and caudate nucleus (0.96 ml/g) are less than that of cerebral cortex (0.99 ml/g), while the lambda of corpus callosum (0.89 ml/g) is greater than that of centrum semiovale (0.83 ml/g). These regional variations in lambda will assume more importance as PET resolution improves. The impact of using an incorrect lambda will depend upon the sensitivity of the particular CBF measurement technique to errors in lambda.

Herscovitch, P.; Raichle, M.E.

1984-01-01

331

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

332

Nuclear magnetic resonance measurement of skeletal muscle: anisotrophy of the diffusion coefficient of the intracellular water.  

PubMed Central

The anisotropy of the spin-diffusion coefficient Ds of water protons in skeletal muscle has been studied by pulsed NMR methods. The mid-portion of the tibialis anterior muscle of mature male rats was placed in a special sample holder by means of which the muscle fiber orientation theta relative to the diffusion direction could be varied over the range 0 degrees less than or equal to theta less than or equal to 90 degrees. The value of Ds(theta) was determined for theta = 0 degrees, 45 degrees, and 90 degrees. The measured anisotropy Ds(0)/Ds(90) was 1.39, and the value of Ds(0) was 1.39 X 10(-5) cm2/s. These results are interpreted within the framework of a model calculation in which the diffusion equation is solved for a regular hexagonal network similar to the actin-myosin filament network. The large anisotropy, and the large reduction in the value of Ds measured parallel to the filament axes lead to two major conclusions: (a) interpretations in which the reduction in Ds is ascribed to the effect of geometrical obstructions on the diffusion of "free" water are ruled out; and, (b) there is a large fraction of the cellular water associated with the proteins in such a way that its diffusion coefficient is substantially reduced.

Cleveland, G G; Chang, D C; Hazlewood, C F; Rorschach, H E

1976-01-01

333

Water and solute absorption from carbohydrate-electrolyte solutions in the human proximal small intestine: a review and statistical analysis.  

PubMed

The purpose of this study is to summarize water, carbohydrate (CHO), and electrolyte absorption from carbohydrate-electrolyte (CHO-E) solutions based on all of the triple-lumen-perfusion studies in humans since the early 1960s. The current statistical analysis included 30 reports from which were obtained information on water absorption, CHO absorption, total solute absorption, CHO concentration, CHO type, osmolality, sodium concentration, and sodium absorption in the different gut segments during exercise and at rest. Mean differences were assessed using independent-samples t tests. Exploratory multiple-regression analyses were conducted to create prediction models for intestinal water absorption. The factors influencing water and solute absorption are carefully evaluated and extensively discussed. The authors suggest that in the human proximal small intestine, water absorption is related to both total solute and CHO absorption; osmolality exerts various impacts on water absorption in the different segments; the multiple types of CHO in the ingested CHO-E solutions play a critical role in stimulating CHO, sodium, total solute, and water absorption; CHO concentration is negatively related to water absorption; and exercise may result in greater water absorption than rest. A potential regression model for predicting water absorption is also proposed for future research and practical application. In conclusion, water absorption in the human small intestine is influenced by osmolality, solute absorption, and the anatomical structures of gut segments. Multiple types of CHO in a CHO-E solution facilitate water absorption by stimulating CHO and solute absorption and lowering osmolality in the intestinal lumen. PMID:20975111

Shi, Xiaocai; Passe, Dennis H

2010-10-01

334

Evaluation of Solubility and the Gas-Liquid Equilibrium Coefficient of High Concentration Gaseous Ozone to Water  

Microsoft Academic Search

Solubility and the gas-liquid equilibrium coefficient of gaseous ozone to water were examined under higher concentrations of supplied gaseous ozone up to 100 mg\\/L. The experimental and modeling approach was employed to evaluate the gas-liquid equilibrium coefficients and mass transfer of ozone. The gas-liquid equilibrium coefficients were evaluated as 0.35, 0.31 and 0.25 (mg\\/L-liquid)\\/(mg\\/L-gas) at 15, 20 and 30 °C,

Tadao Mizuno; Hiroshi Tsuno

2010-01-01

335

Aqueous solubilities and octanol-water partition coefficients of cymenes and chlorocymenes  

SciTech Connect

Aqueous discharges to the environment from pulp mill bleach plants of dissolved wood degradation products and products of reactions between bleaching chemicals and the pulp are a continuing source of pollution. The aqueous solubilities and octanol-water partition coefficients of o-cymene, m-cymene, p-cymene, 2,3-dichloro-p-cymene 2,5-dichloro-p-cymene, 2,3,6-trichloro-p-cymene and tetrachloro-p-cymene, were determined at 25 C using GC and HPLC methods. These properties correlate well with additive LeBas molar volumes.

Lun, R.; Varhanickova, D.; Shiu, W.Y.; Mackay, D. [Univ. of Toronto, Ontario (Canada). Dept. of Chemical Engineering and Applied Chemistry

1997-09-01

336

Accumulation of lipophilic chemicals in plant cuticles: Prediction from octanol\\/water partition coefficients  

Microsoft Academic Search

Partition coefficients of lipophilic organic compounds have been determined for the system plant cuticle\\/water. The cuticles were isolated enzymatically from leaves of rubber plant (Ficus elastica) and bitter orange (Citrus aurantium) and from fruits of tomato (Lycopersicon esculentum) and green pepper (Capsicum annuum). The sorption in cuticles of 4-nitrophenol, (2,4-dichlo-rophenoxy) acetic acid (2,4-D), 6-chloro-N-ethyl-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine (atrazine), (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), pentachlorophenol (PCP),

Franz Kerler; Jörg Schönherr

1988-01-01

337

Temperature dependence of octanol-water partition coefficient for selected chlorobenzenes  

Microsoft Academic Search

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

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

1997-01-01

338

Research on improving unit thermal efficiency based on absorption heat pump by reducing the circulating water temperature  

Microsoft Academic Search

The system of regenerator cycle based on absorption heat pump, through heating up the feed water by the heat from the circulating cooling water by the absorption of the steam driving absorption heat pump, can reduce the temperature of the circulating water and exhaust steam pressure, thus to improve the thermal efficiency of the unit eventually. In this paper, based

He Yongbing; Wu Shijing; Wang Jixuan

2011-01-01

339

Solar absorptance of black cobalt and black cobalt–silver films and its relation with roughness coefficient  

Microsoft Academic Search

Cobalt oxide and cobalt oxide–silver selective surfaces were prepared in a galvanostatic mode by means an electrodeposition bath, using different deposition times, on stainless steel substrates. Later, the roughness factor of the selective surfaces, were determined in order to establish one relation with the electrodeposition time and the solar absorptance of the black cobalt and black cobalt–silver coatings.

C. E Barrera; L Salgado; U Morales; I González

2001-01-01

340

High-resolution absorption coefficient and refractive index spectra of common pollutant gases at millimeter and THz wavelengths  

Microsoft Academic Search

Dispersive Fourier Transform Spectroscopy (DFTS) provides us with a very precise method of measuring the absorption and refractive index spectra of common pollutant gases. This paper presents the rotational transition lines of Sulfur Dioxide and Carbon Monoxide gas as a function of varying pressure using DFTS for the very first time as a combined study. The relationship between the variation

Nawaf N. Almoayed; Baris C. Piyade; Mohammed N. Afsar

2007-01-01

341

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

PubMed

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

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

2013-06-13

342

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

343

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

344

Pressure-broadening and narrowing coefficients and temperature dependence measurements of CO2 at 2.68 ?m by laser diode absorption spectroscopy for atmospheric applications.  

PubMed

By using a tunable diode laser absorption spectrometer in conjunction with a cryogenically cooled multipath cell, we have revisited the air-induced pressure-broadening coefficients and the narrowing coefficients related to the Dicke effect, as well as the temperature dependences, for the R(18) and R(20) lines of the (10°1)I?(00°0) vibrational band at 2.68 ?m of carbon dioxide. The selected transitions are used to probe in situ CO2 in the troposphere and the lower stratosphere by using balloon-borne laser sensors. The achieved measurements are thoroughly compared to existing former determinations. The impact of processing the in situ atmospheric CO2 spectra with this new set of molecular data is reported. PMID:23416909

Ghysels, M; Durry, G; Amarouche, N

2013-01-23

345

Experimental Determination of the Kinetic Coefficients for Water Using Nucleation and Evaporation Rates: Sensitivity to Vapor Pressure  

Microsoft Academic Search

If we are to understand the growth\\/evaporation rates, nucleation rates, and activation rates of atmospheric aerosol particles, we must have an understanding of the kinetics of mass and energy exchange between the surface of an aerosol particle and the surrounding gas. Laboratory experiments to determine the thermal accommodation alpha t coefficient and condensation coefficient alpha c of liquid water have

R. A. Shaw; D. Lamb

2001-01-01

346

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

Microsoft Academic Search

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

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

1995-01-01

347

Calculated values of the octanol–water partition coefficient and aqueous solubility for aminoazobenzene dyes and related structures  

Microsoft Academic Search

Results from calculations of the logarithm of the octanol–water partition coefficient, log P, and the aqueous solubility, S, for a wide range of arylamine dyes and related structures are presented. Since many arylamine dyes have functional groups that easily form ions, the logarithm of the apparent partition coefficient for dissociative systems, log D, has also been calculated as a function

Krishna L. Bhat; Ashish Garg; Charles W. Bock

2002-01-01

348

Determination of the absorption and scattering coefficients of highly scattering media from the experimentally established temporal distributions of laser pulse intensities  

SciTech Connect

The passage of laser radiation through a scattering medium is studied experimentally. A method of determining the optical characteristics of a scattering media is proposed. The method is based on the measurements of time distributions of the intensity of ultrashort laser pulses for two layer thicknesses of the medium to be studied. The measurements are carried out with the use of a single-photon counting system. The proposed method is used to determine the absorption and scattering coefficients of a model medium from the experimental data.

Danilov, A. A.; Tereshchenko, S. A., E-mail: tsa@miee.ru; P'yanov, I. V.; Gavrikov, A. I. [Moscow State Institute of Electronic Technology (Technical University) (Russian Federation)

2011-12-15

349

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

SciTech Connect

Mass energy-transfer (Mu(sub u)/Rho) and mass energy-absorption coefficients (Mu(sub en)/Rho) are tabulated in units of (sqcm/g) for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general dosimetric interest. Cross sections for photo-effect, incoherent scattering, pair and triplet production are those compiled or generated by the National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards). Corrections are included for in-flight positron annihilation, previously not applied in NIST calculations for energies above 10 MeV.

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

1991-11-01

350

Absorption cold and warm water system utilizing solar heat  

Microsoft Academic Search

An absorbtion cold and warm water system utilizing solar heat is disclosed. Heat source water is obtained by heating water by the solar heat and a main heating source. The system is selectively made to function as a warm water system, a first heat pump and a second heat pump in accordance with temperature conditions associated with the heat source

Y. Hibino; K. Kamejima; Y. Nara

1985-01-01

351

Operation device for absorption cold and warm water system utilizing solar heat  

Microsoft Academic Search

An absorption cold and warm water system utilizing solar heat includes a low temperature heat generator using as a heating source low temperature warm water obtained by heating water by the solar heat, a high temperature generator using an ancillary heat source as a heating source when the system runs short of the solar heat, and a low temperature generator.

Y. Hibino; K. Kamejima; Y. Nara

1985-01-01

352

Test of Etafoam Bouyancy Material for Life Jackets Regarding Water Absorption.  

National Technical Information Service (NTIS)

The buoyancy material ETAFOAM was tested in 1987 with regards to water absorption. The test was performed according to the test protocol described by IMO Res. A. 521 (13). The results have been reevaluated against with the acceptance requirements specifie...

A. Pasche

1994-01-01

353

Terahertz absorption spectrum of water vapor at different humidity at room temperature  

NASA Astrophysics Data System (ADS)

We measured the absorption spectrum of water vapor in 0.2-2.4THz range at different humidity from 17% to 98% at room temperature using Er: doped fiber laser (IMRA America Inc.) based terahertz time-domain spectroscopy. The experiments were performed in a nitrogen-purged cage at atmosphere environment to obtain the reference and water absorption information. The seventeen absorption lines were observed due to water molecular rotations in the ground vibration state. The first three absorption lines at low frequencies increase with humidity, following the Beer-Lambert Law, while some of high frequency lines were found to decrease with humidity. These effects will be discussed. The observed line broadening is due to collisions occurring among water and nitrogen molecules.

Xin, Xuying; Altan, Hakan; Matten, David; Saint, Angelamaria; Alfano, Robert

2006-03-01

354

Effective parametrization of overlapping water vapor and carbon dioxide absorption bands  

Microsoft Academic Search

This report presents a new effective method which can be used to compute both the transmittance and the atmospheric radiation fluxes in the overlapping water vapor and carbon dioxide absorption bands.

K. M. Firsov; A. A. Mitsel

1997-01-01

355

Constraining the water vapor uptake coefficient in ambient cloud droplet formation  

NASA Astrophysics Data System (ADS)

Cloud droplet formation depends on the condensation of water vapor on ambient aerosols, the rate of which is strongly affected 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. An analysis of ten globally relevant data sets of cloud condensation nuclei is used to constrain ?c, and find that rapid activation kinetics (?c > 0.1) is uniformly prevalent. This means that uncertainty in water vapor accommodation on droplets is less than previously thought and resolves a long-standing issue in cloud physics.

Raatikainen, T.; Nenes, A.; Seinfeld, J. H.; Morales, R.; Moore, R. H.; Lathem, T. L.; Lance, S.; Padro, L. T.; Lin, J. J.; Cerully, K. M.; Bougiatioti, A.; Cozic, J.; Ruehl, C.; Chuang, P. Y.; Anderson, B. E.; Flagan, R. C.; Jonsson, H.; Mihalopoulos, N.; Smith, J. N.

2013-05-01

356

Measurement of the absorption coefficient for light laterally propagating in light-emitting diode structures with In{sub 0.2}Ga{sub 0.8}N/GaN quantum wells  

SciTech Connect

A procedure for measuring the absorption coefficient for light propagating parallel to the surface of a GaN-based light emitting diode chip on a sapphire substrate is suggested. The procedure implies the study of emission from one end face of the chip as the opposite end face is illuminated with a light emitting diode. The absorption coefficient is calculated from the ratio between the intensities of emission emerging from the end faces of the sapphire substrate and the epitaxial layer. From the measurements for chips based on p-GaN/In{sub 0.2}Ga{sub 0.8}N/n-GaN structures, the lateral absorption coefficient is determined at a level of (23 {+-} 3)cm{sup -1} at a wavelength of 465 nm. Possible causes for the discrepancy between the absorption coefficients determined in the study and those reported previously are analyzed.

Lelikov, Yu. S.; Bochkareva, N. I.; Gorbunov, R. I.; Martynov, I. A.; Rebane, Yu. T.; Tarkin, D. V.; Shreter, Yu. G. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: YShreter@mail.ioffe.ru

2008-11-15

357

[Coefficient of refraction of water and aqueous solutions in the optical frequency range in the vicinity of naphione].  

PubMed

Within the present experimental working it has been shown that in the vicinity of naphione (ion-exchange membrane) the water refraction coefficient grows approximately by a factor of 1.1 in comparison with its value in a liquid. The refractive coefficient changes at the wavelength of about 50 microns. The effect of the refractive coefficient is measured by the pH value and the temperature of the liquid. In the experimental study of the "glycerin/water" mixture at different concentrations it has been found that the refractive coefficient may increase because naphione surface attracts the dipole of water clusters. This effect occurs due to the swelling of naphione in water and its surface takes a charge. PMID:23272575

Bunkin, N F; Kozlov, V A; Ignat'ev, P S; Suiazov, N V; Shkirin, A V; Atakhodzhaev, I A

358

An Instrument for the Measurement of Spectral Attenuation Coefficient and Narrow Angle Volume Scattering Function of Ocean Waters.  

National Technical Information Service (NTIS)

A new instrument has been developed for the study of those optical properties of ocean water that affect the transmission of image-forming light. The instrument performs simultaneous measurements of the volume attenuation coefficient and the volume scatte...

R. W. Austin T. J. Petzold

1975-01-01

359

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

Microsoft Academic Search

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

Victor Chiriac; Florea Chiriac

2010-01-01

360

Static Characteristics of Absorption Chiller-Heater Supplying Cold and Hot Water Simultaneously  

NASA Astrophysics Data System (ADS)

Absorption chiller-heaters which can supply both chilled water and hot water at the same time, are used for cooling and heating air conditioning systems. In this paper, we classified absorption cold and hot water generating cycles and control methods, studied these absorption cycles by cycle simulation. In economizer cycle, condensed refrigerant which heats hot water is transported to cooling cycle and used effectively for cooling chilled water, Concerning with transported condensed refrigerant, there are two methods, all condensed refrigerant or required refrigerant for cooling are transported to cooling cycle, and required refrigerant method is better for energy saving. Adding improvement of solution control to this economizer cycle, simultaneous cold and hot water supplying chiller-heaters have good characteristics of energy saving in the all region.

Inoue, Naoyuki; Irie, Tomoyoshi

361

Estimating phospholipid membrane-water partition coefficients using comprehensive two-dimensional gas chromatography.  

PubMed

Recent studies have shown that membrane-water partition coefficients of organic chemicals can be used to predict bioaccumulation and type I narcosis toxicity more accurately than the traditional K(OW)-based approach. In this paper, we demonstrate how comprehensive two-dimensional gas chromatography (GC × GC) can be used to estimate such membrane-water partition coefficients (K(PLW)s), focusing in particular on phosphatidyl choline based lipids. This method performed well for a set of 38 compounds, including polycyclic aromatic hydrocarbons, polychlorinated benzenes and biphenyls, and substituted benzenes including some phenols and anilines. The average difference between the estimated and the measured log K(PLW) values of 0.47 log units is smaller than in the case of a log K(OW) correlation approach but larger than seen using a polyparameter linear free energy relationship based approach. However, the GC × GC based method presents the advantage that it can be applied to mixtures of chemicals that are not completely identified, such as petroleum hydrocarbon mixtures. At the same time, our application of the GC × GC method suffered larger errors when applied to certain hydrogen bonding compounds due to the inability of the GC × GC capillary columns phases that we used to interact with analytes via hydrogen bond donation/electron acceptance. PMID:22397714

Tcaciuc, A Patricia; Nelson, Robert K; Reddy, Christopher M; Gschwend, Philip M

2012-03-07

362

Evaluating coal tar–water partitioning coefficient estimation methods and solute–solvent molecular interactions in tar phase  

Microsoft Academic Search

Equilibrium partitioning coefficients between an industrial coal tar sample and water (KCT\\/w) were determined for 41 polar and nonpolar solutes in batch systems. Together with literature values, 69 KCT\\/w data were analyzed using the following model approaches: Raoult’s law, the single parameter linear free energy relationship (SPLFER) with octanol–water partitioning coefficients (Kow), the linear solvation energy relationships (LSERs), SPARC and

Satoshi Endo; Wanjing Xu; Kai-Uwe Goss; Torsten C. Schmidt

2008-01-01

363

Transporters involved in glucose and water absorption in the Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) anterior midgut.  

PubMed

Little is known about insect intestinal sugar absorption, in spite of the recent findings, and even less has been published regarding water absorption. The aim of this study was to shed light on putative transporters of water and glucose in the insect midgut. Glucose and water absorptions by the anterior ventriculus of Dysdercus peruvianus midgut were determined by feeding the insects with a glucose and a non-absorbable dye solution, followed by periodical dissection of insects and analysis of ventricular contents. Glucose absorption decreases glucose/dye ratios and water absorption increases dye concentrations. Water and glucose transports are activated (water 50%, glucose 33%) by 50 mM K(2)SO(4) and are inhibited (water 46%, glucose 82%) by 0.2 mM phloretin, the inhibitor of the facilitative hexose transporter (GLUT) or are inhibited (water 45%, glucose 35%) by 0.1 mM phlorizin, the inhibitor of the Na(+)-glucose cotransporter (SGLT). The results also showed that the putative SGLT transports about two times more water relative to glucose than the putative GLUT. These results mean that D. peruvianus uses a GLUT-like transporter and an SGLT-like transporter (with K(+) instead of Na(+)) to absorb dietary glucose and water. A cDNA library from D. peruvianus midgut was screened and we found one sequence homologous to GLUT1, named DpGLUT, and another to a sodium/solute symporter, named DpSGLT. Semi-quantitative RT-PCR studies revealed that DpGLUT and DpSGLTs mRNA were expressed in the anterior midgut, where glucose and water are absorbed, but not in fat body, salivary gland and Malpighian tubules. This is the first report showing the involvement of putative GLUT and SGLT in both water and glucose midgut absorption in insects. PMID:20570749

Bifano, Thaís D; Alegria, Thiago G P; Terra, Walter R

2010-06-04

364

Simulation and performance analysis of a 4-effect lithium bromide-water absorption chiller  

SciTech Connect

Performance simulation has been conducted for a 4-effect lithium bromide-water chiller, capable of substantial performance improvement over state-of-the-art double-effect cycles. The system investigated includes four condensers and four desorbers coupled together, forming an extension of the conventional double-effect cycle; based on prior analytical studies, a parallel flow system was preferred over series flow, and double-condenser coupling was employed, to further improve performance. A modular computer code for simulation of absorption systems (ABSIM) was used to investigate the performances of the cycle. The simulation was carried out to investigate the influence of some major design parameters. A coefficient of performance around 2.0 (cooling) was calculated at the design point, with a heat supply temperature of 600{degrees}F (315{degrees}C) at the solution outlet from the high temperature desorber. With some optimization of the weak (pumped) solution flowrate and of the solution split among the four desorbers, this COP may be raised above 2.2.

Grossman, G. [Technion-Israel Institute of Technology, Haifa (Israel); Zaltash, A.; DeVault, R.C. [Oak Ridge National Lab., TN (United States)

1995-02-01

365

Water absorption by secondary organic aerosol and its effect on inorganic aerosol behavior  

SciTech Connect

The hygroscopic nature of atmospheric aerosol has generally been associated with its inorganic fraction. In this study, a group contribution method is used to predict the water absorption of secondary organic aerosol (SOA). Compared against growth measurements of mixed inorganic-organic particles, this method appears to provide a first-order approximation in predicting SOA water absorption. The growth of common SOA species is predicted to be significantly less than common atmospheric inorganic salts such as (NH{sub 4}){sub 2}SO{sub 4} and NaCl. Using this group contribution method as a tool in predicting SOA water absorption, an integrated modeling approach is developed combining available SOA and inorganic aerosol models to predict overall aerosol behavior. The effect of SOA on water absorption and nitrate partitioning between the gas and aerosol phases is determined. On average, it appears that SOA accounts for approximately 7% of total aerosol water and increases aerosol nitrate concentrations by approximately 10%. At high relative humidity and low SOA mass fractions, the role of SOA in nitrate partitioning and its contribution to total aerosol water is negligible. However, the water absorption of SOA appears to be less sensitive to changes in relative humidity than that of inorganic species, and thus at low relative humidity and high SOA mass fraction concentrations, SOA is predicted to account for approximately 20% of total aerosol water and a 50% increase in aerosol nitrate concentrations. These findings could improve the results of modeling studies where aerosol nitrate has often been underpredicted.

Ansari, A.S.; Pandis, S.N.

2000-01-01

366

A comparison of water binding and mobility in contact lens hydrogels from NMR measurements of the water self-diffusion coefficient  

Microsoft Academic Search

Measurements of the water self-diffusion coefficient were made for a set of nine commercially available contact lens hydrogels, both at equilibrium water content (EWC) and as a function of reduced water content, using the pulsed field gradient NMR method. The data were shown to lie approximately on a universal curve, suggesting that water content (WC) itself was the predominant factor

P. McConville; J. M. Pope

2000-01-01

367

Integrated absorption intensity and Einstein coefficients for the O2 a 1?g-X 3?g- (0,0) transition: A comparison of cavity ringdown and high resolution Fourier transform spectroscopy with a long-path absorption cell  

NASA Astrophysics Data System (ADS)

The two experimental techniques of cavity ringdown spectroscopy and high-resolution, long-path Fourier transform spectroscopy have been used to measure quantitative absorption spectra and determine the integrated absorption intensity (Sint,B) for the O2 a 1?g-X 3?g- (0,0) band. Einstein A-factors and radiative lifetimes for the O2 a 1?g v=0 state have been derived from the Sint,B values. The two methods give values for the integrated absorption intensity that agree to within 2%. The value recommended from the results of this study is Sint,B=3.10+/-0.10×10-24 cm molecule-1, corresponding to an Einstein-A coefficient of A=2.19+/-0.07×10-4 s-1 and a radiative lifetime of ?rad=76 min. The measurements are in excellent agreement with the recent absorption study of Lafferty et al. [Appl. Opt. 37, 2264 (1998)] and greatly reduce the uncertainty in these parameters, for which accurate values are required for determination of upper stratospheric and mesospheric ozone concentrations.

Newman, Stuart M.; Lane, Ian C.; Orr-Ewing, Andrew J.; Newnham, David A.; Ballard, John

1999-06-01

368

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.

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

1992-01-01

369

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...

370

Characteristic Effective Medium Approximation Calculations of The Effective Optical Properties: Optical Constants, Optical Conductivity, Absorption Coefficient and Skin Depth of Ultra Thin Ag-SiO Super Lattices  

NASA Astrophysics Data System (ADS)

The effective optical properties: optical constants, optical conductivity, absorption coefficient and skin depth of an ultra thin Ag-SiO super lattice are calculated using the Characteristic Effective Medium Approximation. The calculations start with the values for the effective Optical Constants of the identity period of the designated super lattice as corrected within an effective medium approximation derived on the basis of the Characteristic Matrix Technique. Via this method the effective optical constants of a bilayer that consists of two thin layers, each of which has a thickness much less than the wavelength of the incident radiation, are established. This method, distinct in its final forms from the previous Geometric Effective Medium Approximation, introduces a more consistent parallelism with the fundamental theory of the Characteristic Matrix Technique, and does lead to a simplified analog of a multilayer that can be viewed as one system of definite effective optical constants. Examples of comparative calculations of the effective values of: the optical constants, optical conductivity, absorption coefficient, and skin depth of an ultra thin Ag-SiO super lattice of 110 Å identity period using the newly derived Characteristic Effective Medium Approximation and the replaced Geometric Effective Medium Approximation show definite differences. The new approximation promises for further corrections in the optical properties of other arbitrary thin multilayer structures whose constituent layers have optical constants of documented values.

Abu El-Haija, A. J.

2002-10-01

371

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.

2012-01-01

372

Water vapor absorption spectrum measurements and its application in concentration measurement  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

373

Absorption cross sections for water vapor from 183 to 193 nm  

Microsoft Academic Search

Absorption cross sections for water vapor at 184.9 nm were measured using a standard low-pressure mercury lamp light source, optically filtered to isolate the spectral region near the emission line. The light from the source was detected using a solar-blind phototube. Experiments were performed over a wide range of water column amounts, using neat water vapor and water vapor\\/nitrogen mixtures,

Christopher A. Cantrell; Audrey Zimmer; Geoffrey S. Tyndall

1997-01-01

374

Determination of the reaction rate coefficient of sulphide mine tailings deposited under water.  

PubMed

The efficiency of a water cover to limit dissolved oxygen (DO) availability to underlying acid-generating mine tailings can be assessed by calculating the DO flux at the tailings-water interface. Fick's equations, which are generally used to calculate this flux, require knowing the effective DO diffusion coefficient (Dw) and the reaction (consumption) rate coefficient (Kr) of the tailings, or the DO concentration profile. Whereas Dw can be accurately estimated, few studies have measured the parameter Kr for submerged sulphide tailings. The objective of this study was to determine Kr for underwater sulphide tailings in a laboratory experiment. Samples of sulphide mine tailings (an approximately 6 cm layer) were placed in a cell under a water cover (approximately 2 cm) maintained at constant DO concentration. Two tailings were studied: TA1 with high sulphide content (83% pyrite) and TA2 with low sulphide content (2.8% pyrite). DO concentration was measured with a microelectrode at various depths above and below the tailings-water interface at 1 mm intervals. Results indicate that steady-state condition was rapidly attained. As expected, a diffusive boundary layer (DBL) was observed in all cases. An iterative back-calculation process using the numerical code POLLUTEv6 and taking the DBL into account provided the Kr values used to match calculated and experimental concentration profiles. Kr obtained for tailings TA1 and TA2 was about 80 d(-1) and 6.5 d(-1), respectively. For comparison purposes, Kr obtained from cell tests on tailings TA1 was lower than Kr calculated from the sulphate production rate obtained from shake-flask tests. Steady-state DO flux at the water-tailings interface was then calculated with POLLUTEv6 using tailings characteristics Dw and Kr. For the tested conditions, DO flux ranged from 608 to 758 mg O2/m(2)/d for tailings TA1 and from 177 to 221 mg O2/m(2)/d for tailings TA2. The impact of placing a protective layer of inert material over the tailings was also investigated for tailings TA1 (with high sulphide content). A protective layer of only 5 cm reduced the DO flux into the tailings at about 5 mg/m(2)/d, compared to 608 mg O2/m(2)/d without a protective layer, or an approximately 99% reduction in flux. PMID:23906653

Awoh, Akué Sylvette; Mbonimpa, Mamert; Bussière, Bruno

2013-07-29

375

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

376

Water Absorption Behavior and Its Influence on Properties of GRP Pipe  

Microsoft Academic Search

With the rapid development of glass-fiber reinforced plastic (GRP) pipes in civil infrastructure under different environments, it is essential to understand the fundamental mechanisms responsible for the pipe failure. However, research reports on water absorption behavior and its influence on the performance of GRP pipe are few in the literatures. This study provides test results of water diffusion in a

J. Yao; G. Ziegmann

2007-01-01

377

Solar operated water-ammonia absorption heat pump for air-conditioning - Modelling and simulation  

Microsoft Academic Search

This study is devoted to the mathematical modelling of an ammonia---water absorption heat pump adapted to solar air-conditioning and including refrigerant and solution storages. Mathematical simulation permits the prediction of the performance of the system during a 24-h period and allows one to estimate its energetic performance, which is compared with those of systems using water-lithium bromide.

E. Brousse; B. Claudel; J. P. Martine

1983-01-01

378

Nitrogen oxide, water vapor, noctilucent clouds, and radio wave emission and absorption near the mesopause  

Microsoft Academic Search

The paper deals with new methods of detecting nitrogen oxide and water vapor near the mesopause from its emissions. It is shown that changes in water vapor concentration are primarily responsible for ionospheric absorption variations in the D region that are not associated with chromospheric flares and entries of ionizing particles.

V. I. Krasovskii; Z. Ts. Rapoport; A. I. Semenov; V. G. Sobolev; N. N. Shefov

1980-01-01

379

Spectral absorption by marine particles of coastal waters of Baja California  

Microsoft Academic Search

During March 1979 spectral absorptance for the suspended particles of the coastal waters of Baja California was determined by measuring the diffuse transmittance of filters containing the particles with a simply designed spectrophotometer. The absorptancc for the upper water of 20 stations varied by over an order of magnitude, but the spectra were generally similar in shape and indicated that

DALE A. KIEFER; JANICE BEELER SOOHOO

1982-01-01

380

Absorption of airborne molecular iodine by water sprays. [I2WASH  

Microsoft Academic Search

A computer model, I2WASH, which accounts for the effect of hydrolysis reactions between molecular iodine and water, has been developed to predict the rate of removal of gaseous molecular iodine by water sprays. It has been shown that the hydrolysis reactions can affect the concentration driving force of mass transfer for molecular iodine absorption. Thus, factors that affect the hydrolysis

M. F. Albert; R. P. Wichner; P. K. Baumgarten

1986-01-01

381

Diffusion Coefficients In a Water\\/Sodium Dodecyl Sulfate\\/ Penlanol Mlcroemulslon Base and Its Ammonium Hydroxide Analogue  

Microsoft Academic Search

The self-diffusion coefficients were determined in sodium dodecyl sutfale\\/pcnlanol solutions with water and an aqueous concentrated ammonium hydroxide solution using NMR.Replacing water by the ammonium hydroxide solution destabilized the liquid crystalline phase in the system and also reduced the size of the colloidal association structures in the isotropic liquid part.

Roald Skurtveit; Johan Sjöblom; Stig E. Fribcrg; Ching-Chang Yang; Ahsan U. Ahmed

1993-01-01

382

FATE OF DYES IN AQUATIC SYSTEMS. II. SOLUBILITY AND OCTANOL/WATER PARTITION COEFFICIENTS OF DISPERSE DYES  

EPA Science Inventory

Water solubilities were measured for 10 disperse dyes that are mostly of recent vintage. he solubilities and octanol/water partition coefficients are used to predict expected concentration factors for sediment and biota. he results show that these newer disperse dyes are likely t...

383

An evaluation of the SAGE III Version 4 aerosol extinction coefficient and water vapor data products  

NASA Astrophysics Data System (ADS)

Herein, we provide an assessment of the data quality of Stratospheric Aerosol and Gas Experiment (SAGE III) Version 4 aerosol extinction coefficient and water vapor data products. The evaluation is based on comparisons with data from four instruments: SAGE II, the Polar Ozone and Aerosol Measurement (POAM III), the Halogen Occultation Experiment (HALOE), and the Microwave Limb Sounder (MLS). Since only about half of the SAGE III channels have a direct comparison with measurements by other instruments, we have employed some empirical techniques to evaluate measurements at some wavelengths. We find that the aerosol extinction coefficient measurements at 449, 520, 755, 869, and 1021 nm are reliable with accuracies and precisions on the order of 10% in the primary aerosol range of 15 to 25 km. We also believe this to be true of the aerosol measurements at 1545 nm though we cannot exclude some positive bias below 15 km. We recommend use of the 385 nm measurements above 16 km where the accuracy is on par with other aerosol channels. The 601 nm measurement is much noisier (~20%) than other channels and we suggest caution in the use of these data. We believe that the 676 nm data are clearly defective particularly above 20 km (accuracy as poor as 50%) and the precision is also low (~30%). We suggest excluding this channel under most circumstances. The SAGE III Version 4 water vapor data product appears to be high quality and is recommended for science applications in the stratosphere below 45 km. In this altitude range, the mean differences with all four corroborative data sets are no bigger than 15% and often less than 10% with exceptional agreement with POAM III and MLS. Above 45 km, it seems likely that SAGE III water vapor values are increasingly too large and should be used cautiously or avoided. We believe that SAGE III meets its preflight goal of 15% accuracy and 10% precision between 15 and 45 km. We do not currently recommend limiting the SAGE III water vapor data utility in the stratosphere by aerosol loading.

Thomason, L. W.; Moore, J. R.; Pitts, M. C.; Zawodny, J. M.; Chiou, E.-W.

2009-10-01

384

Isotopic difference in the second virial coefficient of water: Another test of the MCY-B description of water dimer thermodynamics  

Microsoft Academic Search

Evaluation has been carried out of the component of the second virial coefficient of steam related to the formation of dimers. The necessary equilibrium constants of dimerization have been evaluated within the MCY-B water pair interaction potential. The calculated isotopic difference in the second virial coefficient reflects the qualitative features found by observation but, nevertheless, the calculation quite distinctly overestimates

Z. Slanina

1990-01-01

385

Determination of Metallic Elements in Water by the Combined Preconcentration Techniques of Ion Exchange and Atomic Absorption Spectrophotometry.  

National Technical Information Service (NTIS)

Having as an aim the utilization of atomic absorption method with flame's excitement, the limits of detection in water of six metals (Ag, Co, Cr, Cu, Ni, Zn) were determined in synthetic samples through atomic absorption spectroscopy. Techniques to optimi...

M. H. Paula

1981-01-01

386

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

PubMed Central

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

Caspary, W F; Kalisch, H

1979-01-01

387

Water Absorption into Construction Materials: Comparison of Neutron Radiography Data with Network Absorption Models  

Microsoft Academic Search

Two different porous building materials have been previously measured and analysed (El-Abd and Milczarek, 2004, IEEE Trans. Nuclear Sci.; El-Abd et al., 2004, J. Phys. D) using neutron radiography to measure the water front position over time. The results from this experimental approach show\\u000a a similar behaviour to the predictions from idealised model structures, in that there is a cross

Cathy J. Ridgway; Patrick A. C. Gane; Abd El-Ghany El Abd; Andrzej Czachor

2006-01-01

388

Measurements and modeling of solar spectral absorption by liquid water clouds  

NASA Astrophysics Data System (ADS)

Cloud absorption of solar radiation has been a controversial topic from the earliest attempts at reconciling aircraft measurements with theoretical calculations of cloud absorption. The measurement of cloud absorption from aircraft above and below a cloud layer (flux divergence) is made difficult by issues of cloud heterogeneity, aircraft coordination, and the radiometric accuracy of the instrumentation. Additionally, nearly all previous measurements of cloud absorption have been made with broadband radiometers. Broadband measurements are fundamentally incapable of distinguishing between the various absorbing constituents, namely, cloud liquid water, gases (most importantly, water vapor), and aerosol particles. Thus, the interpretation of the broadband measurements is problematic. Here we report on spectrally resolved (400-2100 nm, 416 channels) cloud absorption measurements from the Solar Spectral Flux Radiometer (SSFR) from two extensive Pacific marine stratus cloud systems encountered during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4). Measurements of cloud spectral absorptance are compared with detailed plane-parallel radiative transfer calculations. For a high optical thickness and spatially uniform cloud case, the agreement between measurement and model absorptance across the spectrum is better than 0.05, and better than 0.01 in the visible. A lower optical thickness case shows slightly larger residuals between measurement and model. Measurements and modeling are used to illustrate and quantify the various mechanisms of cloud layer absorption including the role of aerosols. A novel technique for single aircraft flux divergence measurements based on conditional sampling (Marshak, 1999) is also presented. The technique uses randomized pairs of above- and below-cloud net irradiances matched at a single non-absorbing wavelength to account for cloud net horizontal divergence. Statistics are calculated from these pairs for the complete spectral range, giving an estimate of the entire cloud scene spectral absorptance. Spectral absorptance measurements of the same cloud scene made from two aircraft with large vertical separation are shown to give less robust results.

Kindel, B. C.; Pilewskie, P.; Schmidt, S.; Coddington, O.

2010-12-01

389

Physicochemical properties of macrogol ointment and emulsion ointment blend developed for regulation of water absorption.  

PubMed

Pressure ulcers can form with excess pressure and shearing stress on skin tissue. Because pressure ulcer is often accompanies by exudates, selection of appropriate topical emulsion ointment is difficult. Blended ointments consisting of emulsion base and water-soluble base are clinically used for adjustment of wound moist environment. Because regulating the amount of wound exudates can enhance treatment efficacy, two new blended ointments were developed. LY-SL blended ointment consisted of lysozyme hydrochloride water-in-oil (w/o) emulsion (LY-cream) and sulfadiazine macrogol (polyethylene glycol) ointment (SL-pasta). TR-SL blended ointment consisted of tretinoin tocoferil oil-in-water (o/w) emulsion (TR-cream) and SL-pasta (TR-SL). LY-SL and TR-SL were applied to Franz diffusion cell with cellulose membranes for the evaluation of water absorption characteristics at 32 °C. Water absorption rate constants (mg/cm(2)/min(0.5)) were 12.5, 16.3 and 34.6 for LY-cream, TR-cream and SL-pasta, respectively. Water absorption rate constants for LY-SL and TR-SL (SL-pasta 70%) exhibited intermediate values of 21.2 and 27.2, as compared to each ointment alone, respectively. Because amount of water absorbed was linearly related to square root of time, it was suggested that water-absorbable macrogol was surrounded by oily ingredients forming matrix structure. This diffusion-limited structure may regulate water absorption capacity. This is the first report of physicochemical properties of macrogol ointment and emulsion ointment blend developed for regulation of water absorption. The blended ointment can properly regulate amount of exudates in wounds and may be useful for treatment of pressure ulcers. PMID:21820500

Noda, Yasuhiro; Watanabe, Kazuya; Sanagawa, Akimasa; Sobajima, Yu; Fujii, Satoshi

2011-07-27

390

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.

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

2013-01-01

391

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

392

Absorption efficiencies and biochemical fractionation of assimilated compounds in the cold water appendicularian Oikopleura vanhoeffeni  

Microsoft Academic Search

Using 68 Ge : 14 C dual-labeling, we investigated the absorption efficiency of diatom carbon for the cold water appendicularian Oikopleura vanhoeffeni.The absorption efficiency of bulk carbon (mean5 67%) was not influenced by body size or ingestion rate. For the first time for a pelagic tunicate, food and feces were fractionated into their major biochemical constituents (i.e., low-molecular-weight compounds, lipid,

Alexander B. Bochdansky; Don Deibel; Richard B. Rivkin

1999-01-01

393

A numerical model for ammonia–water absorption into a constrained microscale film  

Microsoft Academic Search

A one-dimensional, steady state model for absorption of ammonia vapor into a constrained microscale film is presented. A weak solution of ammonia–water flows in a microchannel into which ammonia vapor bubbles are injected in cross flow from a porous wall. A counter flowing coolant solution removes the heat generated due to absorption from the opposite wall. The 1-D, steady state

Ruander Cardenas; Vinod Narayanan

2010-01-01

394

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

2013-01-12

395

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

NASA Astrophysics Data System (ADS)

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 and that the absorption minimum is at a significantly shorter wavelength, i.e., 0.0044 -/+ 0.0006 m-1 at 418 nm. Several spectroscopic features have been identified in the visible spectrum to our knowledge for the first time.

Pope, Robin M.; Fry, Edward S.

1997-11-01

396

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

PubMed

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 and that the absorption minimum is at a significantly shorter wavelength, i.e., 0.0044 ? 0.0006 m(-1) at 418 nm. Several spectroscopic features have been identified in the visible spectrum to our knowledge for the first time. PMID:18264420

Pope, R M; Fry, E S

1997-11-20

397

Development of an Integrating Cavity Absorption Meter to Measure Optical Absorption of Pure Waters and Suspended Particulates.  

National Technical Information Service (NTIS)

The Integrating Cavity Absorption Meter (ICAM) provides 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 p...

R. M. Pope

1990-01-01

398

Isotopic mass dependence of metal cation diffusion coefficients in liquid water  

NASA Astrophysics Data System (ADS)

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 ? m-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 ? m-? with 0 ? ? < 0.2 for Li +, Cl -, Mg 2+, and the noble gases). In this paper, we present new MD simulations and experimental results for Na +, K +, Cs +, and Ca 2+ that confirm the generality of the inverse power-law relation D ? m-?. 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 ? being smallest for those solutes whose motions are most strongly coupled to solvent hydrodynamic modes.

Bourg, Ian C.; Richter, Frank M.; Christensen, John N.; Sposito, Garrison

2010-04-01

399

Determination of water permeability coefficient and its activation energy for rabbit spermatozoa.  

PubMed

Critical tonicity (tonicity at which 50% of cells swell beyond their maximum volume-to-surface area ratio and lyse) of rabbit spermatozoa was measured as 45.6 mOsm at 22 degrees C. To determine the temperature effect on critical tonicity, cells were equilibrated to 15, 25, and 35 degrees C and critical tonicity was measured as 52.9, 42.2, and 32.4 mOsm, respectively. The time taken for rabbit sperm to achieve lysis at these temperatures was measured by exposing cells for increasing times to distilled water. From these results values for the permeability coefficient of rabbit spermatozoa to water (Lp) and its activation energy (Ea) were calculated. At 25 degrees C, Lp was 0.63 micron/min/atm and was clearly temperature dependent; Ea was 17.8 kcal/mol. Rabbit spermatozoa appear to have a low Lp and high Ea, the opposite of the situation seen with spermatozoa from all other species examined to date which have high Lp and low Ea. Nevertheless, the values obtained permit modeling of cooling rates for cell survival during cryopreservation in keeping with cooling rates commonly employed. PMID:7743819

Curry, M R; Redding, B J; Watson, P F

1995-04-01

400

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

Microsoft Academic Search

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

Traugott Scheytt; Petra Mersmann; Ralph Lindstädt; Thomas Heberer

2005-01-01

401

Low-Dimensional Water on Ru(0001); Model System for X-ray Absorption Spectroscopy Studies of Liquid Water  

SciTech Connect

We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

Nordlund, D.; Ogasawara, H.; Andersson, K.J.; Tatarkhanov, M.; Salmeron, M.; Pettersson, L. G. M.; Nilsson, A.

2009-05-11

402

theoretical calculation of the coefficient of viscosity of water by non-equilibrium statistical mechanics of simple liquid  

Microsoft Academic Search

The liquid state, especially water, has long been regarded as the most formidable problem in the field of statistical mechanics.\\u000a The coefficient of viscosity of water is calculated using a simplified model based on the microstructure of water and methods\\u000a similar to that used by Rice et al. (1961) who studied the non-equilibrium statistical mechanics of simple liquids, such as

Shu-Bin Ma; Ye-Li Yuan

1994-01-01

403

Water diffusion coefficients of horizontal soil columns from natural saline-alkaline wetlands in a semiarid area  

Microsoft Academic Search

Water diffusion coefficients of soils directly control the solute (such as nitrogen and phosphorous) movement in wetlands,\\u000a which greatly influences the water quality of rivers. The processes of water diffusion in natural saline-alkaline wetland\\u000a soils were simulated by using horizontal soil columns from the Erbaifangzi (EBFZ) wetland in the Xianghai National Natural\\u000a Reserve of China in 2001. The results showed

Junhong Bai; Wei Deng; Baoshan Cui; Hua Ouyang

2007-01-01

404

Nonlinear absorption coefficient and relative refraction index change for an asymmetrical double ?-doped quantum well in GaAs with a Schottky barrier potential  

NASA Astrophysics Data System (ADS)

In this work we are reporting the energy level spectrum for a quantum system consisting of an n-type double ?-doped quantum well with a Schottky barrier potential in a Gallium Arsenide matrix. The calculated states are taken as the basis for the evaluation of the linear and third-order nonlinear contributions to the optical absorption coefficient and to the relative refractive index change, making particular use of the asymmetry of the potential profile. These optical properties are then reported as a function of the Schottky barrier height (SBH) and the separation distance between the ?-doped quantum wells. Also, the effects of the application of hydrostatic pressure are studied. The results show that the amplitudes of the resonant peaks are of the same order of magnitude of those obtained in the case of single ?-doped field effect transistors; but tailoring the asymmetry of the confining potential profile allows the control the resonant peak positions.

Rojas-Briseño, J. G.; Martínez-Orozco, J. C.; Rodríguez-Vargas, I.; Mora-Ramos, M. E.; Duque, C. A.

2013-09-01

405

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 Tm2O3, Yb2O3 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

406

60-GHz oxygen band: precise broadening and central frequencies of fine-structure lines, absolute absorption profile at atmospheric pressure, and revision of mixing coefficients  

NASA Astrophysics Data System (ADS)

The 60-GHz band of 16O2 was studied at room temperature and at low (up to 4 Torr) and atmospheric pressures. Precision measurement of central frequencies, self-broadening, and N2-broadening parameters of fine-structure transitions up to N = 27 was performed by use of a spectrometer with radio-acoustic detection (RAD). The measured parameters are compared with GEISA/HITRAN databanks, MPM92, and other known data. An improved set of the oxygen fine-structure spectroscopic constants is obtained. The absorption profile was recorded in the range 45 96 GHz for laboratory air and pure oxygen at atmospheric pressure by use of a resonator spectrometer with noise level of about ± 0.05 dB/km, and used for deducing the first-order line mixing coefficients and for quantitative assessment of second-order mixing effects. A refined set of MPM parameters is derived from the new data and presented here.

Tretyakov, M. Yu.; Koshelev, M. A.; Dorovskikh, V. V.; Makarov, D. S.; Rosenkranz, P. W.

2005-05-01

407

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

408

Empirical relationships between the 1-octanol\\/water partition coefficient and nine physicochemical properties  

Microsoft Academic Search

For many years, pharmacologists have used partition coefficients to predict biological activity, and more recently, environmental scientists have used them to predict the biological activity of contaminants in aquatic systems. Because the partition coefficients of many compounds of environmental significance are not available, it would be useful to relate partition coefficients to other, more readily available, properties. To this end,

Helene Mailhot; Robert Henry Peters

1988-01-01

409

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

410

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

SciTech Connect

A compound`s bioconcentration factor (BDF) is the most commonly used indicator of its tendency to accumulate in aquatic organisms from the surrounding medium. Because it is expensive to measure, the BCF is generally estimated from the octanol/water partition coefficient (K{sub ow}), but currently used regression equations were developed from small data sets that do not adequately represent the wide range of chemical substances now subject to review. To develop and improved method, the authors collected BCF data in a file that contained information on measured BCFs and other key experimental details for 694 chemicals. Log BCF was then regressed against log K{sub ow} and chemicals with significant deviations from the line of best fit were analyzed by chemical structure. The resulting algorithm classifies a substance as either nonionic or ionic, the latter group including carboxylic acids, sulfonic acids and their salts, and quaternary N compounds. Log BCF for nonionics is estimated from log K{sub ow} and a series of correction factors if applicable; different equations apply for log K{sub ow} 1.0 to 7.0 and >7.0. For ionics, chemicals are categorized by log K{sub ow} and a log BCF in the range 0.5 to 1.75 is assigned. Organometallics, nonionics with long alkyl chains, and aromatic azo compounds receive special treatment. The correlation coefficient and mean error for log BCF indicate that the new method is a significantly better fit to existing data than other methods.

Meylan, W.M.; Howard, P.H.; Aronson, D.; Printup, H.; Gouchie, S. [Syracuse Research Corp., North Syracuse, NY (United States). Environmental Science Center; Boethling, R.S. [Environmental Protection Agency, Washington, DC (United States). Office of Pollution Prevention and Toxics

1999-04-01

411

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

412

Origin of the Low Frequency Sound Absorption in Sea Water.  

National Technical Information Service (NTIS)

Temperature-jump measurements in sea water over the time domain 0.00001 to 0.01 sec reveal a single relaxation of 0.00015 sec at 9.7C, which appears to correspond to the approximately 1 kHz relaxation found from long range sound propagation. Laboratory me...

E. Yeager F. Fisher J. Miceli R. Bressel

1973-01-01

413

Origin of the Low Frequency Sound Absorption in Sea Water.  

National Technical Information Service (NTIS)

Temperature-jump measurements in sea water over the time domain 1/10,000 to 1/100 sec reveal a single relaxation of 150 micro at 9.7C, which appears to correspond to the approximately 1 kHz relaxation found from long range sound propagation. Laboratory me...

E. Yeager F. H. Fisher J. Miceli R. Bressel

1972-01-01

414

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...

415

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

NASA Astrophysics Data System (ADS)

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

Ptashnik, Igor V.

2007-11-01

416

Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance.  

PubMed

Expanding our previously proposed "time segment analysis" for a two-layered turbid medium, this study attempted to selectively determine the absorption coefficient (?a) of the bottom layer in a four-layered human head model with time-domain near-infrared measurements. The difference curve in the temporal profiles of the light attenuation between an object and a reference medium, which are obtained from Monte Carlo simulations, is divided into segments along the time axis, and a slope for each segment is calculated to obtain the depth-dependent ?a(?aseg). The reduced scattering coefficient (?s') of the reference is determined by curve fitting with the temporal point spread function derived from the analytical solution of the diffusion equation to the time-resolved reflectance of the object. The deviation of ?aseg from the actual ?a is expressed by a function of the ratio of ?aseg in an earlier time segment to that in a later segment for mediums with different optical properties and thicknesses of the upper layers. Using this function, it is possible to determine the ?a of the bottom layer in a four-layered epoxy resin-based phantom. These results suggest that the method reported here has potential for determining the ?a of the cerebral tissue in humans. PMID:24057194

Sato, Chie; Shimada, Miho; Tanikawa, Yukari; Hoshi, Yoko

2013-09-01

417

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

NASA Astrophysics Data System (ADS)

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

Saikia, Dip

2008-04-01

418

Investigation of alpha and beta self-absorption factors in the calibration of water sample measurements.  

PubMed

Detector efficiencies and self-absorption factors for a variety of sample preparation methods and naturally occurring dissolved ions have been studied for the gross alpha and gross beta measurement of water samples. The most consistent results are obtained for samples prepared by evaporation of small volumes of water under an infrared lamp. Due to its uniform and homogeneous deposition in the cupped stainless steel planchet, CaCO? was found to best serve as the dry residue radionuclide carrier in this study. Detector efficiencies and self-absorption factors for gross alpha and gross beta measurements closely follow the expected exponential and logarithmic dependence, respectively. PMID:22739965

Valentin, C P; Kratky, J; Brandl, A

2012-08-01

419

Properties of organic-water mixtures. 13. Self-diffusion coefficients of Na\\/sup +\\/ in glycerol triacetate-water mixtures  

Microsoft Academic Search

Self-diffusion coefficients, D, of Na\\/sup +\\/ in water solutions of glycerol triacetate (GTA) were obtained at 25°C as a function of water fraction, f\\/sub v\\/, and sodium perchlorate concentration. The latter was used to produce miscibility of water and GTA over the composition range studied. At constant NaClOâ concentration, D decreases rapidly with water content, qualitatively as expected from the

Harold O. Phillips; Arthur J. Shor; Arthur E. Marcinkowsky; Kurt A. Kraus

1977-01-01

420

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

SciTech Connect

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

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

1992-02-01

421

Instruments and methods for measuring the backward-scattering coefficient of ocean waters  

NASA Astrophysics Data System (ADS)

The backward-scattering coefficient b b is an important optical property that plays a central role in studies of ocean-color remote sensing, suspended particle distributions, water clarity, and underwater visibility. We investigate the fixed-angle backscattering sensor approach for the application of measuring b b . Analysis shows that the sensor response to volume scattering can be expressed as the integral of the volume scattering function (VSF) over the backward angles (90 180 ) weighted by the sensor-response function. We present a procedure for determining the sensor-response function that contains all the information necessary to calibrate the sensor fully to measure the VSF at a nominal backscattering angle. It is shown that, for fixed-angle backscattering sensors, b b is most accurately estimated when the sensor-response function covers the middle range of backscattering angles, roughly 110 160 , where the shape of the VSF has the least variability. Backscattering at and near the end angles, namely, 90 and 180 , are least correlated with b b . We describe a variety of spectral backscattering sensors that we have developed, and we present their sensor-response functions.

Maffione, Robert A.; Dana, David R.

1997-08-01

422

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

423

Relationships between water attenuation coefficients derived from active and passive remote sensing: a case study from two coastal environments.  

PubMed

Relationships between the satellite-derived diffuse attenuation coefficient of downwelling irradiance (K(d)) and airborne-based vertical attenuation of lidar volume backscattering (?) were examined in two coastal environments. At 1.1 km resolution and a wavelength of 532 nm, we found a greater connection between ? and K(d) when ? was computed below 2 m depth (Spearman rank correlation coefficient up to 0.96), and a larger contribution of K(d) to ? with respect to the beam attenuation coefficient as estimated from lidar measurements and K(d) models. Our results suggest that concurrent passive and active optical measurements can be used to estimate total scattering coefficient and backscattering efficiency in waters without optical vertical structure. PMID:21691366

Montes, Martin A; Churnside, James; Lee, Zhongping; Gould, Richard; Arnone, Robert; Weidemann, Alan

2011-06-20

424

[Fog water absorption by the leaves of epiphytes and non - epiphytes in Xishuangbanna].  

PubMed

Xishuangbanna is located at the northern margin of tropics. Its climate is different from that of typical tropics, but the rainforest there is not very different from that of the typical tropics in Southeast Asia. The main problems in Xishuangbanna are seasonal drought and low temperature. Fog may contribute to the development of rainforest here, but related studies are few. This study is aimed to know whether the leaves of epiphytes and non - epiphytes in Xishuangbanna can directly absorb fog water and contribute to their water status recovery, and whether epiphytes are more competent than non - epiphytes in their leaf fog water absorption. The study was conducted in dry season, and four species of epiphytes and six species of non - epiphytes were investigated. The effect of fog was imitated by spraying leaves with distilled water. For epiphytes and non - epiphytes, their leaf water potential (phi), relative water content (RWC), and amount of absorbed water increased gradually with the time of spraying, but the phi of epiphytes increased more quickly than that of non - epiphytes. The leaves of epiphytes Bolbitis scandens and Rhaphidophora decursiva could absorb fog water more quickly, and increase their RWC more greatly than those of non - epiphytes, indicating that these epiphytes were more competent than non - epiphytes in their leaf fog water absorption. The fog water absorption capacity of the leaves in epiphytic orchid Coelogyne occultata and Staurochilus dawsonianus was lower than that in Amischotolype hispida and Mananthus patentflora, but higher than that in other four non - epiphytes. The phi of epiphytes at early evening when no fog was formed was significantly lower than that at early morning, suggesting that fog water was absorbed by epiphytes at night to improve their leaf water status. Non - epiphytes did not need to absorb fog water directly through leaves, and they could recover their leaf water status through absorbing soil water by root system. Epiphytes except C. occultata had a much more leaf biomass than non - epiphytes, which was also beneficial to their leaf fog water absorption. Because there was abundant fog in dry season in Xishuangbanna, the phi of test ten species was higher than -0.8 MPa, indicating that water stress was not serious in dry season. PMID:16964926

Zheng, Yulong; Feng, Yulong

2006-06-01

425

Using a non-invasive stable isotope tracer to measure the absorption of water in humans.  

PubMed

The development of solutions that prevent dehydration or promote adequate re-hydration play a vital role in preventing fatigue during exercise, however, the methods commonly used to assess the hydration ability of such solutions are invasive and often assess the components of absorption separately. This paper describes using a non-invasive deuterium tracer technique that assesses gastric emptying and intestinal absorption simultaneously to evaluate the uptake of water during rest and exercise. The kinetics of absorption are further examined by mathematical modelling of the data generated. For the rest group, 0.05 g/kg of body weight of deuterium, contained in gelatine capsules, was ingested with ordinary tap water and saliva samples were collected every 5 min for one hour while the subject remained seated. The deuterium was administered as above for the exercise group but sample collection was during one hour of exercise on a treadmill at 55% of the subject's maximum heart rate. The enrichment data for each subject were mathematically modelled and the parameters obtained were compared across groups using an independent samples t-test. Compared with the rest condition, the exercise group showed delayed absorption of water as indicated by significant differences for the modelling parameters t2, t1/2, maximum absorption rate and solution absorption amount at t1. Labelling with a deuterium tracer is a good measure of the relative rate ingested fluids are absorbed by the body. Mathematical modelling of the data generates rates of maximum absorption and allows calculation of the percentage of the solution that is absorbed at any given time during the testing period. PMID:15052581

Hill, Rebecca J; Bluck, Leslie J C; Davies, Peter S W

2004-01-01

426

Effects of increased near-infrared absorption by water vapor on the climate system  

NASA Astrophysics Data System (ADS)

Recent improvements in the spectroscopic data for water vapor have significantly increased the near-infrared absorption in models of the Earth's atmosphere. The climatic effects of increased near-infrared absorption have been simulated with the latest Community Atmosphere Model (CAM3). The shortwave parameterization in CAM3 has been updated to minimize differences between CAM3 and line-by-line (LBL) calculations based upon the High Resolution Transmission (HITRAN) spectroscopic database issued in 2001. The new model reproduces LBL calculations of the near-infrared absorption to within 0.9% ± 1.4% and the near-infrared heating rates to within 0.02 ± 0.02 K d-1. Estimates of the global annual mean shortwave absorption by water vapor have been calculated from the editions of the AFGL and HITRAN databases issued in 1982 and 2001, respectively. The main changes in water vapor spectroscopy during this period are the addition of many missing weak lines and increased estimates of line strength in near infrared wavelengths. The clear-sky and all-sky shortwave absorption increase by 4.0 W m-2 and 3.1 W m-2, respectively, in calculations replacing the old with the new spectroscopic parameters. The atmosphere becomes warmer, moister, and more stable with the increased absorption in simulations with sea surface temperatures either prescribed from observations or predicted using a slab-ocean model. The latent heat flux and precipitation both decrease by approximately 2%. Hence the additional absorption has the effect of weakening the hydrological cycle in the atmospheric model.

Collins, William D.; Lee-Taylor, Julia M.; Edwards, David P.; Francis, Gene L.

2006-09-01

427

The effect of three fire regimes on stream water quality, water yield and export coefficients in a tropical savanna (northern Australia)  

Microsoft Academic Search

The effects of three fire regimes—(1) burning early in the dry season (June), (2) burning late in the dry season (September) and (3) not burning (protected from wildfires)—on the water quality, water yield and export coefficients of three intermittent streams, which flow between December and June, have been examined in a tropical savanna in northern Australia. The study was conducted

S. A. Townsend; M. M. Douglas

2000-01-01

428

Evaluation of distribution coefficients for the prediction of strontium and cesium migration in a natural sand at different water contents  

NASA Astrophysics Data System (ADS)

Contaminant distribution coefficient determined under saturated conditions are often used to model solute transport in the vadose zone. However, the water content of porous media may affect the transport behaviour of conservative and sorbing solutes. We performed column experiments using sand from Chernobyl area and we investigated the transport of tritiated water as conservative tracer, ^{85}Sr and ^{134}Cs as reactive solutes at different water saturation levels. The results indicate that when the Kd model is applicable, a decrease of the water content leads to a decrease of the Kd value.

Szenknect, S.; Gaudet, J. P.; Dewiere, L.

2003-05-01

429

Relating inverse-derived basal sliding coefficients beneath ice sheets to basal water supply and other large-scale variables  

NASA Astrophysics Data System (ADS)

Variations in basal conditions that determine basal sliding are important boundary conditions for large-scale ice-sheet models, but remain largely uncertain below modern ice sheets. Previous modeling studies have used relatively sophisticated inverse control methods to deduce patterns of basal stress or roughness, fitting to observed velocities. Here a much simpler method is used, running the model forward in time and periodically increasing or decreasing the basal sliding coefficient locally depending on whether the model ice elevation is higher or lower than observed. In contrast to our earlier application, the method is applied to Antarctica without any constraints of basal temperature or water availability. Then the deduced pattern of sliding coefficients is related to distributions of basal temperature, water supply, sub-grid-scale topography and other variables, with the goal of deriving an empirical parameterization of sliding coefficients for continental-scale models. ~

Pollard, David; DeConto, Robert

2013-04-01

430

Prediction of solubilities of pharmaceutical compounds in water + co-solvent systems using an activity coefficient model  

Microsoft Academic Search

The prediction of the solubilities of pharmaceutical compounds in solvent and co-solvent systems can be achieved using a one-parameter Wilson activity coefficient model. The pharmaceutical compounds tested included salicylic acid, acetaminophen, benzocaine, acetanilide and phenacetin. The solvent employed was water, and the co-solvents studied were ethanol, methanol, and 1,4-dioxane. The solubilities of solutes in a binary mixture of water and

Hiroyuki Matsuda; Kenta Kaburagi; Kiyofumi Kurihara; Katsumi Tochigi; Kazuo Tomono

2010-01-01

431

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

432

Simultaneous optimization of linear firing shrinkage and water absorption of triaxial ceramic bodies using experiments design  

Microsoft Academic Search

In the development and manufacture stages of floor and wall ceramic tiles, firing shrinkage and water absorption are basically determined by the combination of raw materials and frequently used as quality control parameters. This configures the ideal scenario to apply the techniques of experiments design, often used in various other areas, to model those properties of such ceramics bodies. In

S. L Correia; D Hotza; A. M Segadães

2004-01-01

433

Neutron radiography study of water absorption in porous building materials: anomalous diffusion analysis  

Microsoft Academic Search

Dynamic neutron radiography was applied to obtain the experimental data concerning the kinetics of the wetting process in two different types (fired-clay and siliceous brick) of porous construction materials. The technique provides accurate experimental data concerning the first instants as well as the advanced stages of the imbibing process. A significant difference in water absorption parameters, contrasting the materials studied,

Abd El-Ghany El Abd; Jacek J. Milczarek

2004-01-01

434

Determination of osmium in waste water by graphite furnance atomic absorption spectrometry  

Microsoft Academic Search

The determination of osmium in waste water by electrothermal atomic absorption spectrometry (AAS) with a graphite furnace atomiser has been investigated. The atomisation characteristics of osmium on the atomiser were found to result in optimal ashing and atomisation temperatures of 300–500 and 3180 °C, respectively.

Tohru Suzuki; Mamoru Miyada; Kiyohisa Ohta; Satoshi Kaneco; Takayuki Mizuno

1998-01-01

435

DETERMINING BERYLLIUM IN DRINKING WATER BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROSCOPY  

EPA Science Inventory

A direct graphite furnace atomic absorption spectroscopy method for the analysis of beryllium in drinking water has been derived from a method for determining beryllium in urine. Ammonium phosphomolybdate and ascorbic acid were employed as matrix modifiers. The matrix modifiers s...

436

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

Microsoft Academic Search

Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al (2002 J. Phys.: Condens. Matter14 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

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

2008-01-01

437

Determination of Barium in Bottled Drinking Water by Graphite Furnace Atomic Absorption Spectrometry  

Microsoft Academic Search

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

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

1988-01-01

438

Performance of water-cooled lithium bromide absorption units for solar energy applications  

Microsoft Academic Search

This article includes a comprehensive review of the variables that can influence the proper choice of all the solar energy system components for the cooling of buildings. Optimization of absorption unit COPs and the required temperature levels of the heat source directly affect the choice of systems external to the unit. Improved COPs influence the effectiveness of hot water storage

1976-01-01

439

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, S.; Chomsaksakul, W.; Sonsuk, M.

2000-10-01

440

Theoretical analysis of ammonia-water absorption cycles for refrigeration and space conditioning systems  

Microsoft Academic Search

A numerical model for the performance of an ammonia-water absorption cycle in solar air conditioning, refrigeration, and heat pump systems are presented. The configurations comprise a solar driven generator, a rectifier, condenser, evaporator, absorber, preheater, and a subcooler. Cooling modes involve supplying heat to the evaporator from the space to be cooled and transferring the heat to the ambient environment

S. C. Kaushik; S. C. Bhardwaj

1982-01-01

441

A Numerical Study of Ammonia-Water Absorption Into a Constrained Microscale Film  

Microsoft Academic Search

A one-dimensional, steady state, semi-empirical model of an ammonia-water microscale bubble absorber is presented. The geometry consists of a microchannel through which a solution of ammonia-water flows. Ammonia vapor is injected through one of the walls of the channel. A counter flowing coolant solution removes the heat generated due to absorption from the opposite wall. The 1-D, steady state species

Vinod Narayanan

2008-01-01

442

Microchannel component technology for system-wide application in ammonia\\/water absorption heat pumps  

Microsoft Academic Search

A novel miniaturization technology for binary-fluid heat and mass exchange was developed and numerous components were fabricated for demonstration as different parts of an ammonia\\/water absorption heat pump. Short lengths of microchannel tubes are placed in an array, with several such arrays stacked vertically. The ammonia\\/water solution flows in falling film\\/droplet mode on the outside of the tubes while coupling

Srinivas Garimella; Matthew D. Determan; J. Mark Meacham; Sangsoo Lee; Timothy C. Ernst

2011-01-01

443

Absorption heat pump for a potable water supply in a solar house  

Microsoft Academic Search

Solar houses usually have good potential in arid areas. These areas often suffer from not only a shortage of conventional energy sources, but also of potable water supplies. In this study, a solar air-conditioning system including an absorption heat pump, already in production since the early 1980s, is described for potable water production while performing its air-conditioning duty in a

S. Elshamarka

1991-01-01

444

In vitro percutaneous absorption of cadmium from water and soil into human skin  

Microsoft Academic Search

The objective was to determine percutaneous absorption of cadmium as the chloride salt from water and soil into and through human skin. Soil (Yolo County 65-California-57-8) was passed through 10-, 20-, and 48-mesh sieves. Soil retained by 80 mesh was mixed with radioactive cadmium-109 at 13 ppb. Water solutions of cadmium-109 at 116 ppb were prepared for comparative analysis. Human

R. C. Wester; H. I. Maibach; L. Sedik; J. Melendres; S. DiZio; M. Wade

1992-01-01

445

Depth-resolved water column spectral absorption of sunlight by phytoplankon during the Southern Ocean Gas Exchange (SOGasEx) Lagrangian tracer experiments  

NASA Astrophysics Data System (ADS)

Optical measurements made during gas exchange tracer experiments in the Southern Ocean, Atlantic sector near 51°S, 38°W from March-April 2008 (SOGasEx) were used to develop daily integrated depth- resolved PAR absorbed by phytoplankton. Particulate and phytoplankton pigment spectral absorption coefficients (ap and aph), and methanol-extracted chlorophyll-a concentrations (chl-a) from discrete samples within and below the upper mixed layer (40 stations) were combined with data from optical casts where chlorophyll-a and cdom fluorescence and PAR scalar irradiance were measured (11 stations), PAR Kd was measured from a buoy free of ship shadow for 0-5m (11 stations), and Wetlabs AC-9 whole water absorption coefficients to 150m were measured (14 stations, with 3 in common with fluorescence data) to estimate depth-resolved values for both total spectral absorption and spectral PAR irradiance. By combining depth-adjusted spectral absorption of phytoplankton pigments (aph) with depth-adjusted PAR spectral irradiance we estimated depth-resolved daily PAR irradiance absorbed by photosynthetic pigments. These data can be compared with time-integrated primary production measurements conducted on deck where solar exposure or lamp exposure was modified to simulate a range of depths. Such a synthesis should improve our estimates of depth-integrated daily primary production, and ultimately contribute to refining estimates of carbon export rates to be incorporated into a carbon budget and CO2 air-sea flux models for the SOGasEx experiments.

Hargreaves, B. R.

2008-12-01

446

Application of UNIFAC models to partition coefficients of biochemicals between water and n-octanol or n-butanol  

Microsoft Academic Search

The objective of this work is to examine whether the various UNIFAC models can represent phase behavior of biochemicals in the dilution solution such as partition coefficients (log Pi). Especially, the log Pi of a solute in the n-octanol\\/water system was used as main target for the examination in this work. First, the log Pi of common chemical solutes was

Hidetoshi Kuramochi; Hidetaka Noritomi; Daisuke Hoshino; Satoru Kato; Kunio Nagahama

1998-01-01

447