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1

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

E-print Network

to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, Edward S. Fry Committee Members, Robert A. Kenefick Alexei Sokolov Goong... Chen Head of Department, Edward S. Fry May 2008 Major Subject: Physics iii ABSTRACT Measuring Optical Absorption Coefficient of Pure Water in UV Using the Integrating Cavity Absorption Meter. (May 2008) Ling Wang, B.S., Peking...

Wang, Ling

2008-10-10

2

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

2011-12-01

3

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

4

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

NASA Technical Reports Server (NTRS)

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

Grant, William B.

1990-01-01

5

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

6

IR Absorption Coefficients for the Quantification of Water in Hydrous Ringwoodite  

NASA Astrophysics Data System (ADS)

Raman spectroscopy, combined with the 'Comparator technique' has been developed to determine water contents ranging from a few wt ppm to wt% in glasses and nominally anhydrous minerals including garnets, olivine, and SiO2 polymorphs (Thomas et al. 2009). The routine is one promising example of quantification tools to determine mineral specific molar absorption coefficients (?) for IR spectroscopy. Mineral specific absorption coefficients are required because general IR calibrations do not necessarily apply to minerals with water incorporated as hydroxyl point defects. Here we utilize the 'Comparator technique' to provide ?-values for a set of synthetic Fe-free (Fo100) and Fe-bearing (Fo90, Fo87, Fo83, Fo60) ringwoodites, as well as for ?-Mg2GeO4. Ringwoodite is considered one of the major phases of the Earth's lower transition zone (520-660 km depth) and the knowledge of its absolute water storage capacity is essential for modeling the Earth's deep water cycle. Samples were synthesized at variable P-T conditions in a multi-anvil press and cover a range of OH contents. Single-crystals were characterized using X-ray diffraction and IR spectroscopy. Mineral specific IR absorption coefficients were calculated from independently determined water contents from Raman spectroscopy. Unpolarized IR spectra of Mg-ringwoodite show broad absorption features in the OH region with band maxima at ~2350, 2538, 3130, 3172, 3598 and 3688 cm-1. In the spectra of Fe-bearing ringwoodite and ?-Mg2GeO4 the maxima of the main OH band are shifted to 3244 cm-1 (Fo60) and 3207 cm-1, respectively. For Mg-ringwoodite with the mean wavenumber (area-weighted average of the peak position) of 3170 cm-1 an ?-value of 191500 ± 38300 L cm-2/ molH2O was determined. For the ringwoodites with Fo90, Fo87 and Fo83 composition and the mean wavenumbers of 3229 cm-1, 3252 cm-1 and 3163 cm-1 values of 123600 ± 24700 L cm-2/ molH2O, 176300 ± 52900 L cm-2/ molH2O and 155000 ± 46500 L cm-2/ molH2O were computed. Our value for pure Mg-ringwoodite is in very good agreement with the value according to Libowitzky & Rossman (1997) and the absorption coefficient proposed by Balan et al. (2008), but is higher than the extrapolated value from Koch-Müller & Rhede (2010). However, in case of the sample with Fo60 composition water content and ?-value determined here are in excellent agreement with those calculated by Koch-Müller & Rhede (2010). Here, we will further discuss general IR calibrations and the dependence of ? on structure, composition and frequency for the (Mg,Fe)2SiO4 polymorphs in the mantle. We agree with the findings of Koch-Müller & Rhede (2010), which report that using the calibrations according to Paterson (1982) and Libowitzky & Rossman (1997) leads to a water content underestimation in case of Fe-rich (Fay-Fo60) samples. At this point this cannot be generalized for Mg-rich ringwoodite. References Thomas et al. (2009), Phys. Chem. Mineral., 36, 489-509. Libowitzky & Rossman (1997), Am. Mineral., 82, 1111-1115. Koch-Müller & Rhede (2010), Am. Mineral., in press. Paterson (1982), Bull. Mineral. (Paris), 105, 20-29.

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

2010-05-01

7

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

Microsoft Academic Search

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

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

2007-01-01

8

Volumetric mass transfer coefficients characterising VOC absorption in water/silicone oil mixtures  

E-print Network

Engineering Journal 221 (2013) 308-314" DOI : 10.1016/j.cej.2013.01.102 #12;Abstract The physical absorption biotechnologies to treat hydrophobic Volatile Organic Compounds (VOCs; [1-4]). In such gas- liquid-liquid processes, the mass transfer coefficient KLa is a key parameter in estimating reactor performance [5

Paris-Sud XI, Université de

9

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

10

Prediction of absorption coefficients by pulsed laser induced photoacoustic measurements.  

PubMed

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

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

2014-06-01

11

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

EPA Science Inventory

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

12

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

PubMed Central

Because spring water quality from alpine karst aquifers can change very rapidly during event situations, water abstraction management has to be performed in near real-time. Four summer events (2005-2008) at alpine karst springs were investigated in detail in order to evaluate the spectral absorption coefficient at 254nm (SAC254) as a real-time early warning proxy for faecal pollution. For the investigation Low-Earth-Orbit (LEO) Satellite-based data communication between portable hydrometeorological measuring stations and an automated microbiological sampling device was used. The method for event triggered microbial sampling and analyzing was already established and described in a previous paper (Stadler et al., Wat. Sci. Technol. 58(4): 899-909, 2008). Data analysis including on-line event characterisation (i.e. precipitation, discharge, turbidity, SAC254) and comprehensive E. coli determination (n > 800) indicated that SAC254 is a useful early warning proxy. Irrespective of the studied event situations SAC254 always increased 3 to 6 hours earlier than the onset of faecal pollution, featuring different correlation phases. Furthermore, it seems also possible to use SAC254 as a real-time proxy parameter for estimating the extent of faecal pollution after establishing specific spring and event-type calibrations that take into consideration the variability of the occurrence and the transferability of faecal material It should be highlighted that diffuse faecal pollution from wildlife and live stock sources was responsible for spring water contamination at the investigated catchments. In this respect, the SAC254 can also provide useful information to support microbial source tracking efforts where different situations of infiltration have to be investigated. PMID:20962406

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

2011-01-01

13

GAMMA RAY ABSORPTION COEFFICIENTS FOR ELEMENTS AND MIXTURES  

Microsoft Academic Search

Mass gamma ray total and energy absorption coefficients are tabulated as ; a function of energy from 0.2 to 10 Mev for various elements, mixtures, and ; compounds. The data presented here are based on the latest published results of ; Dr. G. White Grodstein, National Bureau of Standards. Polynomial expressions are ; given for approximation of absorption coefficients for

Capo

1961-01-01

14

Does the photon-diffusion coefficient depend on absorption?  

E-print Network

Does the photon-diffusion coefficient depend on absorption? T. Durduran and A. G. Yodh Department the controversy over the precise form of the photon diffusion coefficient and suggest that it is largely diffusion coefficient gives better agreement with theory than the traditionally accepted photon diffusion

Boas, David

15

Determination of optical absorption coefficient with focusing photoacoustic imaging.  

PubMed

Absorption coefficient of biological tissue is an important factor for photothermal therapy and photoacoustic imaging. However, its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique to quantify the target optical absorption coefficient. It utilizes the ratio of the amplitude of the peak signal from the top boundary of the target to that from the bottom boundary based on wavelet transform. This method is self-calibrating. Factors, such as absolute optical fluence, ultrasound parameters, and Gru?neisen parameter, can be canceled by dividing the amplitudes of the two peaks. To demonstrate this method, we quantified the optical absorption coefficient of a target with various concentrations of an absorbing dye. This method is particularly useful to provide accurate absorption coefficient for predicting the outcomes of photothermal interaction for cancer treatment with absorption enhancement. PMID:22734746

Li, Zhifang; Li, Hui; Zeng, Zhiping; Xie, Wenming; Chen, Wei R

2012-06-01

16

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

17

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

Microsoft Academic Search

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

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

1990-01-01

18

Determination of low absorption coefficients from absorptance measurements on thin films  

NASA Astrophysics Data System (ADS)

We discuss the determination of the absorption coefficient (?) from absorptance ( A) measurements on thin films in the low absorption range, especially in the case of amorphous semiconductor films studied by photothermal spectroscopies. We propose approximate expressions between A and ?, determine their range of validity and compare them to expressions used by other authors.

Driss-Khodja, K.; Gheorghiu, A.; Theye, M.-L.

1985-09-01

19

Analyzing Water's Optical Absorption  

NASA Technical Reports Server (NTRS)

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

2002-01-01

20

Absolute determination of the x-ray absorption coefficient of strontium in the K edge region  

NASA Astrophysics Data System (ADS)

The x-ray absorption coefficient for strontium in the K edge region (15.6-17.6 keV) is determined on aqueous solution of Sr(NO3)2 in a micrometer cell. A series of absorption spectra of the solution and of solvent is recorded for the thickness of the liquid layer varied stepwise between 1 and 2.5 mm. The linear absorption coefficient of Sr and water is determined in a variational procedure whereby small systematic errors of the micrometer setting, of signal detection and of disclination of cell windows are eliminated in one step. The results confirm the data on Sr mass absorption coefficient in some recent tabulations in the smooth regions below the edge and further away from it, but show systematically higher values in the wider energy range above the edge. The tabulated data for water agree with the experiment within 4% in the entire range of measurement.

Hauko, R.; Gomilšek, J. Padežnik; Ar?on, I.; Kodre, A.

2014-10-01

21

Energy-absorption coefficients for ?-rays in compounds or mixtures  

Microsoft Academic Search

In 1953 Fano warned that for gamma -rays the simple (Bragg) law of combination for a mixture of elements does not hold exactly for the mass energy absorption coefficient if bremsstrahlung generation is appreciable. This comment has been routinely ignored since then, however, causing errors that may be significant in some circumstances. This note defines the correct method for deriving

F H Attix

1984-01-01

22

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

23

A pattern fit coefficient for water application  

Microsoft Academic Search

A new coefficient, the pattern fit coefficient for water application, Pa, is introduced. It expresses the differences between an applied and any predetermined water pattern. The efficiency of many irrigation systems and methods are evaluated by comparing them to a uniform pattern. In several cases, however, strip patterns are more efficient and, therefore, preferred (e.g. small row crops, early growing

Victor Alchanatis; Ilan Amir

1990-01-01

24

Absorption Coefficient Measurrement of Monochromatized Synchrotron Radiation at 0.65 - 1.3 A Interval for Some Biological Objects.  

National Technical Information Service (NTIS)

The results of the measurement of absorption coefficients for some biological objects such as pea (Pisum sativum), wheat (Triticum aestivum), tobacco (Nicotiana tabacum- alpha ) seeds, as well as the distilled water are presented. The measurement has been...

T. M. Avakian, I. P. Karabekov, M. A. Martirossian

1977-01-01

25

A method for monitoring nuclear absorption coefficients of aviation fuels  

NASA Technical Reports Server (NTRS)

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

Sprinkle, Danny R.; Shen, Chih-Ping

1989-01-01

26

Optimization of the acoustic absorption coefficients of certain functional absorbents  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

27

High temperature measurement of water vapor absorption  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

28

Measurements of the absorption coefficient of stratospheric aerosols  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

29

Determination of absorption coefficients in highly scattering media from changes in attenuation and phase  

Microsoft Academic Search

The accurate, quantitative analysis of absorption and scattering properties in tissue is a central problem in biochemical optics, in particular for the determination of hemoglobin and oxyhemoglobin concentrations. Because of light scattering, the absolute concentrations of these chromophores (i.e., the absorption coefficient) cannot easily be inferred. A new method for the estimation of the absorption coefficients in scattering media, based

Matthias Kohl; Russell Watson; Mark Cope

1996-01-01

30

Temperature Dependence of the Submillimeter Absorption Coefficient of Amorphous Silicate Grains  

NASA Astrophysics Data System (ADS)

We have measured mass absorption coefficients of amorphous silicate materials for wavelengths between 100 ?m and 2 mm (5-100 cm-1) and at temperatures between 300 and 10 K. For both interstellar analog MgSiO3 and simple silica SiO2, we find evidence for a strong temperature and frequency dependence. We define two distinct wavelength regimes, 500 ?m-1 mm and 100-250 ?m, for which the absorption coefficient presents different trends with frequency. To evaluate this frequency dependence, we fit our absorption coefficient using two power laws with spectral index ? that varies with temperature. We do not find a significant variation of ? with temperature between 100 and 250 ?m, whereas between 500 ?m and 1 mm a pronounced anticorrelation between T and ? exists. Globally, ?-values decrease from 2.5 to 1.5 between 10 and 300 K. This anticorrelation for interstellar analog grains has the same trend as the one observed using the balloon-borne experiment PRONAOS. We show that physisorbed water is not responsible for the observed temperature and frequency dependence and that OH groups could be at the origin of the submillimeter properties of the materials. As discussed in the literature, OH groups are often related to tunneling processes in two-level systems (TLS). In the case of the more complex MgSiO3 silicates, TLS could also be produced by the Mg+2 ions, which act as network modifiers, similar to how they act with OH groups.

Boudet, N.; Mutschke, H.; Nayral, C.; Jäger, C.; Bernard, J.-P.; Henning, T.; Meny, C.

2005-11-01

31

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

32

Measurement of the absorption coefficient using the sound-intensity technique  

NASA Technical Reports Server (NTRS)

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

Atwal, M.; Bernhard, R.

1984-01-01

33

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

NASA Technical Reports Server (NTRS)

The theory for calculating the absorption of laser radiation by hydrogen is outlined for the temperatures and pressures of common laboratory plasmas. Nonhydrogenic corrections for determining the absorption by helium are also included. The coefficients for the absorption of He-Ne laser radiation at the wavelengths of 0.633, 1.15, and 3.39 microns in a H plasma is presented for temperatures in the range from 10,000 to 40,000 K and electron number densities in the range from 10 to the 15th power to 10 to the 18th power per cu cm. The total absorption of a H-He plasma calculated from this theory is compared with the measured absorption. The theoretical composition of the H-He absorption is analyzed with respect to the significant absorption processes, inverse bremsstrahlung, photoionization, resonance excitation, and photodetachment.

Stallcop, J. R.

1974-01-01

34

LETTER TO THE EDITOR: Measurements of the XUV mass absorption coefficient of an overdense liquid metal  

NASA Astrophysics Data System (ADS)

The increase in the XUV mass absorption coefficient of liquid aluminium, produced by high-power-laser shock-compression, is measured using XUV laser radiography. At a photon energy of 63 eV a change in the mass absorption coefficient by up to a factor of ~2.2 is determined at densities close to twice that of solid and electron temperatures of the order of 1 eV. Comparison with hydrodynamic simulations indicate that the absorption coefficient scales with density as ?1.3±0.2.

Wolfrum, E.; Allen, A. M.; Al'Miev, I.; Barbee, T. W., Jr.; Burnett, P. D. S.; Djaoui, A.; Iglesias, C.; Kalantar, D. H.; Lee, R. W.; Keenan, R.; Key, M. H.; Lewis, C. L. S.; Machacek, A. M.; Remington, B. A.; Rose, S. J.; O'Rourke, R.; Wark, J. S.

2001-09-01

35

Particle scattering, backscattering, and absorption coefficients: An in situ closure and sensitivity study  

NASA Astrophysics Data System (ADS)

Comparisons between measured and calculated aerosol scattering, backscattering, and absorption coefficients were made based on in situ, ground-based measurements during the Melpitz INTensive (MINT) and Lindenberg Aerosol Characterization Experiment 1998 (LACE 98) field studies. Furthermore, airborne measurements made with the same type of instruments are reviewed and compared with the ground-based measurements. Agreement between measured and calculated values is on the order of ±20% for scattering and backscattering coefficients. A sensitivity analysis showed a large influence on the calculated particle scattering and backscattering coefficients resulting from sizing uncertainties in the measured number size distributions. Measured absorption coefficients were significantly smaller than the corresponding calculated values. The largest uncertainty for the calculated absorption coefficients resulted from the size-dependent fraction of elemental carbon (EC) of the aerosol. A correction for the measured fractions of EC could significantly improve the agreement between measured and calculated absorption coefficients. The overall uncertainty of the calculated values was investigated with a Monte Carlo method by simultaneously and randomly varying the input parameters of the calculations, where the variation of each parameter was bounded by its uncertainty. The measurements were mostly found to be within the range of uncertainties of the calculations, with uncertainties for the calculated scattering and backscattering coefficients of about ±20% and for the absorption coefficients of about ±30%. Thus, to increase the accuracy of calculated scattering, backscattering, and absorption coefficients, it is crucial to further reduce the error in particle number size distribution measurement techniques. In addition, further improvement of the techniques for measuring absorption coefficients and further investigation of the measurement of the fraction of EC of the aerosol is necessary.

Wex, Heike; Neusüß, Christian; Wendisch, Manfred; Stratmann, Frank; Koziar, Christian; Keil, Andreas; Wiedensohler, Alfred; Ebert, Martin

2002-11-01

36

WAVELENGTH-DEPENDENT OPTICAL PROPERTIES, MASS ABSORPTION COEFFICIENTS, AND CLOSURE STUDIES FOR CARBONACEOUS AEROSOLS AT  

E-print Network

WAVELENGTH-DEPENDENT OPTICAL PROPERTIES, MASS ABSORPTION COEFFICIENTS, AND CLOSURE STUDIES Gorkowski and Claudio Mazzoleni, Michigan Technological University R. Subramanian, Droplet Measurement Technologies Arthur Sedlacek, Gunnar Senum, and Stephen Springston, Brookhaven National Laboratory Ari Setyan

37

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

NASA Technical Reports Server (NTRS)

The absorption coefficients of 0.633-, 1.15-, and 3.39-micron laser radiation for a homogeneous H-He plasma have been measured in the temperature range from 12.2 to 21.7 (x 1000 K) and in the electron number density range 0.45 to 6.5 (x 10 to the 17th power per cu cm). Good agreement is found between the experimentally determined total absorption for each of the wavelengths and that calculated from theory. Furthermore, because the 3.39-micron absorption is dominated by inverse bremsstrahlung, while the 0.633-micron absorption is dominated by photoionization and resonance absorption, the experiment indicates a correct assessment by the theory of these individual absorption mechanisms.

Billman, K. W.; Rowley, P. D.; Stallcop, J. R.; Presley, L.

1974-01-01

38

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

39

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

40

Method for measuring small optical absorption coefficients with use of a ShackHartmann  

E-print Network

for measuring absorption at the 1 10 5 cm 1 level in high-quality optical materials. Using a Shack­Hartmann wave and estimated the absorption coefficient from the thermal-rise and decay. Making use of the difference in the slope of the thermal rise, S. Yoshida syoshida@selu.edu is with the Laser Interferometer Gravitational

Tanner, David B.

41

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...

42

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

43

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

Microsoft Academic Search

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

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

2011-01-01

44

[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

45

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

46

Expression of optical diffusion coefficient in high-absorption turbid media  

NASA Astrophysics Data System (ADS)

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

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

1997-12-01

47

Water-related absorption in fibrous diamonds  

NASA Astrophysics Data System (ADS)

Cubic and coated diamonds from several localities (Brasil, Canada, Yakutia) were investigated using spectroscopic techniques. Special emphasis was put on investigation of water-related features of transmission Infra-red and Raman spectra. Presence of molecular water is inferred from broad absorption bands in IR at 3420 and 1640 cm-1. These bands were observed in many of the investigated samples. It is likely that molecular water is present in microinclusions in liquid state, since no clear indications of solid H_2O (ice VI-VII, Kagi et al., 2000) were found. Comparison of absorption by HOH and OH vibrations shows that diamonds can be separated into two principal groups: those containing liquid water (direct proportionality of OH and HOH absorption) and those with stronger absorption by OH group. Fraction of diamonds in every group depends on their provenance. There might be positive correlation between internal pressure in microinclusions (determined using quartz barometer, Navon et al., 1988) and affiliation with diamonds containing liquid water. In many cases absorption by HOH vibration is considerably lower than absorption by hydroxyl (OH) group. This may be explained if OH groups are partially present in mineral and/or melt inclusions. This hypothesis is supported by following fact: in diamonds with strong absorption by silicates and other minerals shape and position of the OH band differs from that in diamonds with low absorption by minerals. Moreover, in Raman spectra of individual inclusions sometimes the broad band at 3100 cm-1 is observed. This band is OH-related. In some samples water distribution is not homogeneous. Central part of the diamond usually contains more water than outer parts, but this is not a general rule for all the samples. Water absorption usually correlated with absorption of other components (carbonates, silicates and others). At that fibrous diamonds with relatively high content of silicates are characterized by molecular water. OH-enriched diamonds contain more carbonatitic material. This was supported by JSPS and grant of University of Russia (No. 09.01.054).

Zedgenizov, D. A.; Shiryaev, A. A.; Kagi, H.; Navon, O.

2003-04-01

48

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

49

Absolute measurement of absorption and scattering coefficients spectra of a multiply scattering medium  

Microsoft Academic Search

On the basis of the diffusion theory model, frequency-domain spectroscopy allows for a quantitative determination of the absorption ((mu) a) and scattering ((mu) s') coefficient spectra of a homogeneous multiple scattering medium. We performed measurements using an intensity modulated light emitting diode (LED) as the light source. The LED's spectral distribution permits the study of a spectral region extending for

Sergio Fantini; Maria A. Franceschini-Fantini; Joshua B. Fishkin; Enrico Gratton

1994-01-01

50

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

E-print Network

Use of textile nanofibers to improve the sound absorption coefficient of drilled panels Conference 23-27 April 2012, Nantes, France 303 #12;Nowadays combinations of textile materials are common possible to assert that the nanofibers textile veils combined with the textile wools, will improve

Paris-Sud XI, Université de

51

Variation of phytoplankton absorption coefficients in the northern South China Sea during spring and autumn  

Microsoft Academic Search

We examined the temporal and spatial variabilities of phytoplankton absorption coefficients (alphaphlambda)) and their relationships with physical processes in the northern South China Sea from two cruise surveys during spring (May 2001) and late autumn (November 2002). A large river plume induced by heavy precipitation in May stimulated a phytoplankton bloom on the inner shelf, causing significant changes in the

J. Wu; H. Hong; S. Shang; M. Dai; Z. Lee

2007-01-01

52

Sound conversion phenomena at the free surface of liquid helium. II. Experimental determination of acoustic coefficients and surface absorption coefficients  

SciTech Connect

The acoustic coefficients of reflection, transmission, and transformation of first-, second-, and gas sound waves incident normally on the free surface of liquid helium have been determined. The experimental results are compared with the theory developed in Part I of this paper. It is shown that equilibrium theories of boundary conditions disagree with the experiments. Nonequilibrium theories, however, which take into account that mass and energy transport processes occur at the liquid-vapor interface of helium II, lead to a very good description of the experimental data below 2 K. Within experimental accuracy the measurements fully confirm several kinetic models of evaporation and energy transport processes. Near the lambda point, deviations from the theory have been found which might be attributed to influences of critical phenomena. The surface absorption coefficients of first-, second-, and gas sound waves could be deduced from the experimental data on the acoustic coefficients, and it is shown that, in agreement with the theory, appreciable energy dissipation occurs at the free surface of helium II when a second-sound or a gas sound wave is incident.

Wiechert, H.; Buchholz, F.I.

1983-05-01

53

Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer  

NASA Astrophysics Data System (ADS)

Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (?) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.

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

2014-09-01

54

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

2007-08-01

55

Temperature- and pressure-dependent absorption coefficients for CO2 and O2 at 193 nm  

NASA Astrophysics Data System (ADS)

Absorption of laser radiation at 193 nm by CO2 and O2 was studied at a series of different temperatures up to 1273 K and pressures up to 1 bar. The spectrum for CO2 was found to be broadband, so that absorption could be fitted to a Beer-Lambert law. On the other hand, the corresponding O2 spectrum is strongly structured and parameterisation requires a more complex relation, depending on both temperature and the product (pressure × absorption path length). In this context, the influence of spectral structure on the resulting spectrally integrated absorption coefficients is discussed. Using the fitting parameters obtained, effective transmissions at 193 nm can be calculated for a wide range of experimental conditions. As an illustration of the practical application of these data, the calculation of effective transmission for a typical industrial flue gas is described.

Hartinger, K. T.; Nord, S.; Monkhouse, P. B.

56

Constrained two-stream algorithm for calculating aerosol light absorption coefficient from the Particle Soot Absorption Photometer  

NASA Astrophysics Data System (ADS)

We present a new correction scheme for filter-based absorption photometers based on a constrained two-stream (CTS) radiative transfer model and experimental calibrations. The two-stream model was initialized using experimentally accessible optical parameters of the filter. Experimental calibrations were taken from literature and from dedicated experiments for the present manuscript. Uncertainties of the model and calibration experiments are discussed and uncertainties for retrieval of absorption coefficients are derived. For single scattering albedos lower than 0.8, the new CTS method and also other correction schemes suffer from the uncertainty of calibration experiments, with an uncertainty of about 20% in the absorption coefficient. For high single scattering albedos the CTS correction significantly reduces error. At a single scattering albedo of about 0.98 the error can be reduced to 30%, whereas errors using the Bond correction (Bond et al., 1999) are up to 100%. The correction scheme was tested using data from an independent experiment. The tests confirm the modeled performance of the correction scheme when comparing CTS to other established correction methods.

Müller, T.; Virkkula, A.; Ogren, J. A.

2013-12-01

57

Chlorophyll-specific absorption coefficients and pigments of phytoplankton off Sanriku, northwestern North Pacific  

Microsoft Academic Search

The variety in shape and magnitude of thein vivo chlorophyll-specific absorption spectra of phytoplankton was investigated in relation to differences in pigment composition\\u000a off Sanriku, northwestern North Pacific. Site-to-site variations of the absorption coefficients,a\\u000a \\u000a ph\\u000a \\u000a * (?), and pigment composition were clearly observed. At warm-streamer stations, higher values ofa\\u000a \\u000a ph\\u000a \\u000a * (440) anda\\u000a ph\\u000a * (650) were found with relatively

Koji Suzuki; Motoaki Kishino; Kousei Sasaoka; Sei-Ichi Saitoh; Toshiro Saino

1998-01-01

58

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

PubMed Central

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

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

1995-01-01

59

WATER VAPOUR ABSORPTION IN TERRESTRIAL ISOPODS  

Microsoft Academic Search

Summary Continuous and intermittent gravimetric measurements have identified active water vapour absorption (WVA) in three species of terrestrial Isopoda. Water activity thresholds for uptake lie in the range 0.92-0.95. Above the threshold, WVA shows non-saturated kinetics; the rectum apparently serves as a supplemen- tary avenue for fluid resorption during rapid uptake. Standardized uptake fluxes, corrected for vapour pressure deficit, can

JONATHAN C. WRIGHT; JOHN MACHIN

1990-01-01

60

Fitting narrow-band models to temperature-dependent, spectral absorption coefficients of fuel vapors  

NASA Astrophysics Data System (ADS)

Accurate modeling of infrared radiation transport through fuel rich cores of fires and other non-premixed combustion processes requires computationally efficient processing of temperature-dependent, spectral absorption coefficients for major fuel vapor species. Spectrally resolved transmissivity band measurements in the mid-infrared and near-infrared have been taken in recent years for numerous small fuel molecules including but not limited to ethane, ethylene, and propylene for a range of temperatures relevant for combustion environments. This paper compares the spectral transmissivity measurements using FTIR for both ethane and ethylene with the HITRAN 2012 edition. Narrow band absorption coefficients and overlap parameters are derived by fitting the spectral transmissivity measurements for ethane, ethylene, and propylene with narrow band models for temperatures up to 1000 K. The resulting fits provide a basis for calculating spectrally resolved infrared radiation transport in fuel rich cores of flames and other combustion processes where these species can be prevalent.

Lecoustre, V. R.; Wakatsuki, K.; Jackson, G. S.

2014-11-01

61

Optical absorption coefficient of laser irradiated wheat seeds determined by photoacoustic spectroscopy  

NASA Astrophysics Data System (ADS)

Present study is concerned with the photoacoustic (PA) assessment of optical absorption coefficient (?) for treated (soaking in the methylene blue dye) and untreated seeds of wheat. The determination of ?, based on the Rosencwaig and Gersho model enables the optical absorption coefficient to be assessed directly from the measured amplitude of PA signal. The obtained ? values were statistically analyzed. The outcome of the analysis shows significant differences in ? values: in the wavelength range from 600 to 700 nm treated (with dye) seeds have higher ? than untreated seeds. These seeds were also irradiated (varying time and intensity) with a laser diode emitting at 650 nm. Germination tests were carried out on both, irradiated and control (no irradiated) seeds. The percentage of normal seedlings from treated seeds was found higher (p ? 0.05) than from control seeds.

Hernández Aguilar, C.; Mezzalama, M.; Lozano, N.; Cruz-Orea, A.; Martínez, E.; Ivanov, R.; Domínguez-Pacheco, A.

2008-01-01

62

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

PubMed

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

Majaron, Boris; Milanic, Matija

2008-01-01

63

Temperature Dependence of the Submillimeter Absorption Coefficient of Amorphous Silicate Grains  

Microsoft Academic Search

We have measured mass absorption coefficients of amorphous silicate materials for wavelengths between 100 mum and 2 mm (5-100 cm-1) and at temperatures between 300 and 10 K. For both interstellar analog MgSiO3 and simple silica SiO2, we find evidence for a strong temperature and frequency dependence. We define two distinct wavelength regimes, 500 mum-1 mm and 100-250 mum, for

N. Boudet; H. Mutschke; C. Nayral; C. Jäger; J.-P. Bernard; T. Henning; C. Meny

2005-01-01

64

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

65

Water- Lithium Bromide-?- Butyrolactone Absorption Refrigerating Machine  

NASA Astrophysics Data System (ADS)

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

Iyoki, Shigeki; Uemura, Tadashi

66

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

67

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

NASA Astrophysics Data System (ADS)

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

Fornasini, P.; Grisenti, R.

2014-10-01

68

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

PubMed

The bond thermal expansion is in principle different from the lattice expansion and can be measured by correlation sensitive probes such as extended x-ray absorption fine structure (EXAFS) and diffuse scattering. The temperature dependence of the coefficient ?bond(T) of bond thermal expansion has been obtained from EXAFS for CdTe and for Cu. A coefficient ?tens(T) of negative expansion due to tension effects has been calculated from the comparison of bond and lattice expansions. Negative lattice expansion is present in temperature intervals where ?bond prevails over ?tens; this real-space approach is complementary but not equivalent to the Grüneisen theory. The relevance of taking into account the asymmetry of the nearest-neighbours distribution of distances in order to get reliable bond expansion values and the physical meaning of the third cumulant are thoroughly discussed. PMID:25362321

Fornasini, P; Grisenti, R

2014-10-28

69

Measurement of mass attenuation coefficients around the K absorption edge by parametric X-rays  

NASA Astrophysics Data System (ADS)

When electrons at relativistic velocities pass through a crystal plate, such as silicon, photons are emitted around the Bragg angle for X-ray diffraction. This phenomenon is called parametric X-ray radiation (PXR). The monochromaticity and directivity of PXR are adequate and the energy can be changed continuously by rotating the crystal. This study measured the mass attenuation coefficient around the K-shell absorption edge of Nb, Zr and Mo as a PXR application of monochromatic hard X-ray radiation sources.

Tamura, Masaya; Akimoto, Tadashi; Aoki, Yohei; Ikeda, Jiro; Sato, Koichi; Fujita, Fumiyuki; Homma, Akira; Sawamura, Teruko; Narita, Masakuni

2002-05-01

70

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

SciTech Connect

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

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

2007-01-15

71

Predicting Soil-Water Partition Coefficients for Cadmium  

E-print Network

Predicting Soil-Water Partition Coefficients for Cadmium S U E N - Z O N E L E E Department and chemical composition, particularly organic matter and metal oxides. The adsorption of Cd(II) followed concentration, greater adsorption was observed for soils with higher organic matter content. To better

Sparks, Donald L.

72

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

NASA Astrophysics Data System (ADS)

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

Zheng, Guangming

73

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

NASA Astrophysics Data System (ADS)

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

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

2002-06-01

74

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

PubMed Central

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

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

2011-01-01

75

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

NASA Astrophysics Data System (ADS)

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.

2011-12-01

76

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

77

The use of X-ray CT to measure diffusion coefficients of heavy ions in water-saturated porous media  

Microsoft Academic Search

X-ray computerized tomography (CT) was applied for the first time to the measurement of diffusion coefficients of heavy ions in water-saturated clay and rock. The mass absorption coefficient of X-rays is high for heavy elements. Thus the migration of heavy ions in the porous samples was measured by the spatio-temporal change in intensity of X-ray CT images. The measurements of

Yoshito Nakashima

2000-01-01

78

Measurement and modeling of infrared nonlinear absorption coefficients and laser-induced damage thresholds in Ge and GaSb  

SciTech Connect

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 {mu}m for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 {mu}m and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al{sub 2}O{sub 3} anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond pulses, respectively.

Wagner, T. J.; Bohn, M. J.; Coutu, R. A. Jr. [Air Force Institute of Technology, Wright Patterson Air Force Base, Ohio 45433 (United States); Gonzalez, L. P.; Murray, J. M.; Guha, S. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Ohio 45433 (United States); Schepler, K. L. [Air Force Research Laboratory, Sensors Directorate, Wright Patterson Air Force Base, Ohio 45433 (United States)

2010-10-15

79

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

E-print Network

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

Jung, Youngeui

2013-01-01

80

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

NASA Astrophysics Data System (ADS)

Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the ? particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient ?? of LH waves due to ? particles. Results show that, the ?? increases with the parallel refraction index n? while deceases with increasing the frequency of LH waves ?LH over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of ?? when ne?8×1019m-3 for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, ? ? 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

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

2014-02-01

81

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

82

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

NASA Astrophysics Data System (ADS)

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

Qu, Yonghua; Zhu, Yeqing; Ge, Xiaoli

2014-03-01

83

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

84

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

SciTech Connect

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

Wu Benxin; Shin, Yung C. [Center for Laser-based Manufacturing, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2006-09-11

85

Spectral absorption coefficient of molten aluminum oxide from 0.385 to 0.780 μm  

Microsoft Academic Search

The spectral extinction coefficient, k{sub λ}, and the absorption coefficient, α{sub λ}, of liquid aluminum oxide were determined from emission measurements on partially molten single-crystal sapphire filaments. Measurements were made at wavelengths from 0.385 to 0.780 μm in both argon and oxygen atmospheres and at 0.650 μm in a 10% Hâ-90% Nâ mixture. The values of α{sub λ} were found

J. K. Richard Weber; Shankar Krishnan; Collin D. Anderson; Paul C. Nordine

1995-01-01

86

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

87

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

NASA Technical Reports Server (NTRS)

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

Ponsardin, Patrick; Browell, Edward V.

1995-01-01

88

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

89

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

NASA Astrophysics Data System (ADS)

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

Vuye, Cedric; Vanlanduit, Steve; Guillaume, Patrick

2009-06-01

90

Temperature modulation of the visible and near infrared absorption and scattering coefficients of human skin.  

PubMed

We determine temperature effect on the absorption and reduced scattering coefficients (mu(a) and mu(s)(')) of human forearm skin. Optical and thermal simulation data suggest that mu( a) and mu(s)(') are determined within a temperature-controlled depth of approximately 2 mm. Cutaneous mu(s)(') change linearly with temperature. Change in mu(a) was complex and irreversible above body normal temperatures. Light penetration depth (delta) in skin increased on cooling, with considerable person-to-person variations. We attribute the effect of temperature on mu(s)(') to change in refractive index mismatch, and its effect on mu(a) to perfusion changes. The reversible temperature effect on mu (s)(' ) was maintained during more than 90 min. contact between skin and the measuring probe, where temperature was modulated between 38 and 22 degrees C for multiple cycles While temperature modulated mu(s)(' ) instantaneously and reversibly, mu(a) exhibited slower response time and consistent drift. There was a statistically significant upward drift in mu(a) and a mostly downward drift in mu( s)(') over the contact period. The drift in temperature-induced fractional change in mu(s)(') was less statistically significant than the drift in mu(s)('). Deltamu( s)(') values determined under temperature modulation conditions may have less nonspecific drift than mu(s)(') which may have significance for noninvasive determination of analytes in human tissue. PMID:12683845

Khalil, Omar S; Yeh, Shu-Jen; Lowery, Michael G; Wu, Xiaomao; Hanna, Charles F; Kantor, Stanislaw; Jeng, Tzyy-Wen; Kanger, Johannes S; Bolt, Rene A; de Mul, Frits F

2003-04-01

91

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 ...

92

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

E-print Network

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

Firoozabadi, Abbas

93

DIFFUSE SOUND ABSORPTION COEFFICIENT DETERMINATION FROM IN SITU SPECIFIC BOUNDARY IMPEDANCE MEASUREMENTS BY THE SOUND INTENSITY TECHNIQUE  

Microsoft Academic Search

At present, the most part of errors on acoustic prediction and modelling of acoustic designs are as a result of the use of low precision sound absorption coefficients. To predict the acoustic performance of a material, within the infinity possible forms of assembly and constructive terminations, is mathematically complex. On the other hand, the most used method for the sound

Adrián Montoya; Ricardo Pesse

94

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

PubMed

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

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

2001-01-01

95

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

96

Anomalous atmospheric spectral features between 300 and 310 nm interpreted in light or new ozone absorption coefficient measurements  

NASA Technical Reports Server (NTRS)

Real structure is revealed, by an analysis of continuous scan data from the solar backscattered UV instrument on Nimbus 7, in the backscattered atmospheric albedo region between 300 and 310 nm where spectral anomalies have been reported in ground-based observation. The spectral anomalies are explainable as structure at the 1-5% level in the ozone absorption coefficient, as measured by Bass and Paur (1981). The new absorption coefficient measurements are judged to approach the 1%-level of accuracy in atmospheric radiation calculation, which should resolve discrepancies between different Dobson wavelength pairs and between different instruments and permit the more accurate analysis of such second-order effects as NO emission, SO2 absorption in polluted atmospheres, and Raman scattering effects.

Mcpeters, R. D.; Bass, A. M.

1982-01-01

97

Infrared and millimeter-wavelength absorption by atmospheric water vapor  

NASA Astrophysics Data System (ADS)

An account is given of the current understanding of the atmospheric water vapor window regions from 10 to 1000 GHz, 8-12 microns, and 2-2.5 microns, with attention to the continuum absorption observable in each window region. The observed frequency-dependence in each window is consistent with the concept of far wings that emanate from the bordering water vapor absorption bands; this connection is considered the most prominent basis for the modeling of continuum absorption. It is judged that absorption behavior beyond experimentally measured conditions can be predicted with reasonable confidence.

Thomas, Michael E.

1987-12-01

98

Atmospheric water vapor absorption at 1.3 microm.  

PubMed

Absolute absorption cross sections for water vapor and water vapor/air mixtures were measured in a frequency range encompassing that of the chemically pumped atomic iodine laser. Measurements were made with a temperature-controlled multipass absorption cell and a high-resolution Fourier transform spectrometer. The measurements covered a broad range of water vapor and air pressures. Several techniques of data analysis were used, and the absorption cross section of 2 kPa of water vapor in an atmosphere of air was determined to be 1.1 +/- 0.2 x 10(-24) cm(2) . In this paper, an expression is derived which allows estimation of the absorption cross section for any pressure of water vapor and air. PMID:20454163

Bragg, S L; Kelley, J D

1987-02-01

99

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

100

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

101

Reconstruction of the optical absorption coefficient from photoacoustic signals measured by scanning coaxial probe with regularization methods  

NASA Astrophysics Data System (ADS)

Reconstruction of the absorption coefficient from photoacoustic signals is discussed. The photoacoustic (PA) signals were acquired by using a ring-shaped P(VDF-TrFE) acoustic sensor coaxially arranged with an optical fiber. The acoustic sensor scanned the measured object. The linearized image reconstruction method previously presented by the authors was modified for the measurement with the coaxial probe. The distribution of the absorption coefficient was reconstructed by solving the inverse problem based on the PA wave equation and the photon diffusion equation. The linearized forward model was formulated by solving the partial differential equations with finite element method. To eliminate the effect of the unknown background on the PA signal, the differences between the PA signals measured at different positions were used for the image reconstruction. The image reconstruction method was validated by numerical and phantom experiments. Moreover, the reconstructed images with the Tikhonov and lp sparsity regularization methods were compared from the standpoints of spatial resolution, robustness to noise and quantification of the absorption coefficient.

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

2014-03-01

102

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

103

Measurement of atmospheric precipitable water using a solar radiometer. [water vapor absorption effects  

NASA Technical Reports Server (NTRS)

A technique is described and tested that allows the determination of atmospheric precipitable water from two measurements of solar intensity: one in a water-vapor absorption band and another in a nearby spectral region unaffected by water vapor.

Pitts, D. E.; Dillinger, A. E.; Mcallum, W. E.

1974-01-01

104

Quaternary Diffusion Coefficients in a Protein-Polymer-Salt-Water System Determined by Rayleigh Interferometry  

E-print Network

Quaternary Diffusion Coefficients in a Protein-Polymer-Salt-Water System Determined by Rayleigh in a protein-polymer-salt-water quaternary system. Specifically, we have measured the nine multicomponent diffusion coefficients, Dij, for the lysozyme-poly(ethylene glycol)-NaCl-water system at pH 4.5 and 25 °C

Annunziata, Onofrio

105

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

106

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

PubMed Central

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

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

2010-01-01

107

Atmospheric Precorrected Differential Absorption technique to retrieve columnar water vapor  

SciTech Connect

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

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

1998-09-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

109

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

110

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

PubMed

We used near infrared spectroscopy to obtain concentration dependent glucose absorption spectra in aqueous solutions in the near-infrared range (3800-7500 cm(-1)). Here 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 were able to extract the water displacement coefficients of glucose, and this may offer a new general method using spectroscopy techniques applicable to other water-soluble materials. We also observed red shifts in the absorption bands of water in the hydration shell around solute molecules, which comes from the contribution of the interacting water molecules around the glucose molecules in solutions. The intensity of the red shift gets 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. We also performed the same measurements and analysis with sucrose instead of glucose as solute and compared. PMID:23622436

Jung, Youngeui; Hwang, Jungseek

2013-02-01

111

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

112

Temperature effects on the linear and nonlinear optical absorption coefficient in semi-parabolic quantum wells  

NASA Astrophysics Data System (ADS)

The effects of temperature on the linear and nonlinear optical absorption coeffic ient in semi-parabolic quantum wells are investigated. By the compact density matrix approach, analytical expressions for these optical properties are obtained. Numerical results are used for typical GaAs/AlxGa1-xAs semi-parabolic nanostructure system. In this paper we have presented the behavior of these optical properties as a function of photon energy and inc ident optical intensity considering the effect of temperature. Our results can make a significant contribution both in practical application and in theoretical research.

Kargar, Asghar; Keshavarz, Alireza

2012-09-01

113

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

NASA Astrophysics Data System (ADS)

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

Vigasin, A. A.

2014-11-01

114

A Configurationally-Resolved-Super-Transition-Arrays method for calculation of the spectral absorption coefficient in hot plasmas  

NASA Astrophysics Data System (ADS)

A new method, 'Configurationally-Resolved-Super-Transition-Arrays', for calculation of the spectral absorption coefficient in hot plasmas is presented. In the new method, the spectrum of each Super-Transition-Array is evaluated as the Fourier transform of a single Complex Pseudo Partition Function, which represents the exact analytical sum of the contributions of all constituting unresolved transition arrays sharing the same set of one-electron solutions. Thus, in the new method, the spectrum of each Super-Transition-Array is resolved down to the level of the (unresolved) transition arrays. It is shown that the corresponding spectrum, evaluated by the traditional Super-Transition-Arrays (STA) method [14], is just the coarse-grained Gaussian approximation of the Configurationally-Resolved-Super-Transition-Array. A new computer program is presented, capable of evaluating the absorption coefficient by both the new configurationally resolved and the traditional Gaussian Super-Transition-Arrays methods. A numerical example of gold at temperature 1 keV and density 0.5 gr/cm3, is presented, demonstrating the simplicity, efficiency and accuracy of the new method.

Hazak, G.; Kurzweil, Y.

2012-09-01

115

Optical absorption of pure water in the blue and ultraviolet  

E-print Network

..............................................................................................................61 4.7 Spectralon Absorption and Degradation..........................................................61 V ICAM VERSION-II..................................................................................................63 5.1 Quartz Powder... ocean waters. The resulting information can be used to investigate biological productivity, marine optical properties, interaction of winds and currents with ocean biology, and how human activities influence the oceanic enviroment. The spectral...

Lu, Zheng

2007-09-17

116

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

NASA Technical Reports Server (NTRS)

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

Ma, Q.; Tipping, R. H.

1991-01-01

117

Water diffusion coefficient measurements in the finger by magnetic resonance imaging.  

PubMed

Diffusion coefficients of water have been measured in the fingers of humans by magnetic resonance imaging. It was found that the measured diffusion coefficients increased with subject age in certain regions of the finger but that these regions differed between males and females. The observation of an increased diffusion coefficient with age appears to be inconsistent with a direct-hydration model and possible explanations are given using other models. It is conjectured that the measured diffusion coefficient of water increases with age as a result of structural changes to proteins. PMID:7968287

Damion, R A; Vennart, W; Summers, I R; Ellis, R E

1994-01-01

118

Temperature dependence of infrared absorption by the water vapor continuum near 1200 cm(-1).  

PubMed

Infrared absorption by the water vapor continuum near 1200 cm(-1) has been measured with a lead-tin-telluride diode laser over a 40.5-m optical path. The measurements were made as a function of temperature from 333 K to 473 K; thus, they overlap and extend previous measurements made at temperatures between 293 K and 388 K. Over the entire temperature range studied here, the continuum extinction coefficient increases quadratically with water-vapor partial pressure as expected for the relatively high partial pressures used in these measurements. At temperatures below 398 K. our measured extinction coefficients agree well with previously reported data. At higher temperatures, however, the extinction coefficient is almost independent of temperature and is substantially larger than predicted by empirical formulas. Values of the self-broadening coefficient for water vapor have been extracted from the experimental data, and a possible interpretation of the results involving both dimer and line-broadening effects is presented. PMID:20203777

Montgomery, G P

1978-08-01

119

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

SciTech Connect

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

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

2014-01-01

120

A time-resolved single-pass technique for measuring optical absorption coefficients of window materials under 100 GPa shock pressures.  

PubMed

An experimental method was developed to perform time-resolved, single-pass optical absorption measurements and to determine absorption coefficients of window materials under strong shock compression up to approximately 200 GPa. Experimental details are described of (i) a configuration to generate an in situ dynamic, bright, optical source and (ii) a sample assembly with a lithium fluoride plate to essentially eliminate heat transfer from the hot radiator into the specimen and to maintain a constant optical source within the duration of the experiment. Examples of measurements of optical absorption coefficients of several initially transparent single crystal materials at high shock pressures are presented. PMID:19123545

Li, Jun; Zhou, Xianming; Li, Jiabo

2008-12-01

121

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

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

122

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

123

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

124

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

125

Ultrasonic Velocity and Absorption in Binary Solutions of Silicon Dioxide and Water  

Microsoft Academic Search

Ultrasonic velocity and absorption coefficient at 21 MHz as well as shear viscosity, were measured in an aqueous solution of silicon dioxide over the temperature range of 5 85°C, and the concentration range of 20 to 40% by weight. The absorption coefficient exhibits maximum values at about 25°C. The velocity exhibits a maximum value at approximately 64, 66, 68°C in

Jong-Rim Bae; Seung Yun

1998-01-01

126

Photoelectric quantum efficiencies and filter window absorption coefficients from 20 eV to 10 KeV  

SciTech Connect

Photodiodes with x-ray sensitive photocathodes are commonly used as broadband x-ray detectors in fusion plasma diagnostics. We have measured the photocathode quantum efficiency between 1--500 A of common photocathode materials including aluminum, copper, nickel, gold, three forms of carbon, chromium, and cesium iodide. We have also studied the effects of the experimental environment and long-term cathode aging on the measured quantum efficiencies. In addition, we have measured the x-ray mass-absorption coefficients of x-ray filter windows of Kimfoil, aluminum, polypropylene, and Formvar in energy regions where data were previously unavailable. Measurements between 1--50 A were performed at the Los Alamos Scientific Laboratory's low-energy x-ray calibration facility, while the measurements between 50--500 A were performed at the National Bureau of Standard's synchrotron ultraviolet radiation facility.

Day, R.H.; Lee, P.; Saloman, E.B.; Nagel, D.J.

1981-11-01

127

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

128

Water diffusion coefficients during copper electropolishing and IAN IVAR SUNI2*  

E-print Network

associated with each dissolving Cu ion and on the effective diffusion coefficient of water. Transient state behavior are the same, about one water molecule is associated with each dissolving Cu ion is also consistent with an assumption that six water molecules are associated with each dissolving Cu ion

Suni, Ian Ivar

129

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

...of a substance between water and a lipophilic solvent...into an organism and the potential bioaccumulation of the...substances in the system water/n -octanol and...Measure Bioconcentration Potential of Organic Chemicals...coefficients in an octanol-water system. Journal of...

2014-07-01

130

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

Code of Federal Regulations, 2013 CFR

...of a substance between water and a lipophilic solvent...into an organism and the potential bioaccumulation of the...substances in the system water/n -octanol and...Measure Bioconcentration Potential of Organic Chemicals...coefficients in an octanol-water system. Journal of...

2013-07-01

131

Activity coefficients of bicarbonate, carbonate and calcium ions in sea water  

Microsoft Academic Search

Measurements of pH of sea water samples equilibrated with known partial pressures of CO 2 and with calcite and aragonite have enabled the determination of molal activity coefficient for bicarbonate, carbonate, and calcium ions in two sea water samples at 25°C and 1 atm total pressure. Results are: For standard artificial sea water (chlorinity = 19.0 , titration alkalinity =

Robert A. Berner

1965-01-01

132

Journal of Membrane Science 287 (2007) 126131 Water transport coefficient distribution through the  

E-print Network

such as Nafion require water in order to exhibit high proton conductivity. However, if too much water is present Received 11 August 2006; received in revised form 9 October 2006; accepted 16 October 2006 Available online on experimental measurements of the net water transport coefficient distribution for the first time

133

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

E-print Network

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

Tcaciuc, Alexandra Patricia

134

Water balance in Tenebrio molitor , L. Larvae; the effect of atmospheric water absorption  

Microsoft Academic Search

Fasting mealworms gain weight in 98 and 92, but not in 85% R.H. at rates which increase with humidity and animal size above a threshold of 88.2%. Weight gains are associated with substantial increases in body water content and considerable haemolymph dilution. Blocking the anus eliminates weight gains confirming the rectum as the probable site of atmospheric absorption. No absorption

John Machin

1975-01-01

135

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

Microsoft Academic Search

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

J. H. Hubbell; Stephen M Seltzer

1995-01-01

136

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

137

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

SciTech Connect

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

Streets, W.E.

1994-05-01

138

Feasibility study of ammonia-water vapor absorption heat transformer  

Microsoft Academic Search

Many industrial sectors reject heat to the atmosphere in the form of hot water with a temperature between 40° and 70°C. This low grade heat can be upgraded by using a vapor absorption heat transformer (AHT). The present study considers a single stage AHT with binary mixture of NHâ-HâO as the working fluid. The performance characteristics of the system have

A. Ertas; P. Gandhidasan; J. J. Luthan

1987-01-01

139

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

140

Airborne differential absorption lidar system for water vapor investigations  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

141

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

E-print Network

, (Cambridge U. P. , New York, 1983). J. Stone, "Measurements of the Absorption of Light in Low-Loss Liquids, " Journal of the Optical Society of America 62, 327-333 (1972). Marvin Hass, James W, Davidson, Herbert B. Rosenstock, and Julius Babiskin... of Visible Radiation by Aerosol Particles, " Beitr5ge zur Physik der Atmosphare, 43, 244-254 (1970). Antony D. Clarke, "Integrating sandwich: a new method of measurement of the light absorption coefficient for atmospheric particles, " Appl. Opt. , 21...

Pope, Robin Merl

2012-06-07

142

Infrared Water Vapor Continuum Absorption: New Atmospheric Electrical Measurements and Theory.  

National Technical Information Service (NTIS)

The infrared (IR) continuum absorption, and probably similar absorption at longer wavelengths, can be attributed to populations of electrically-neutral water clusters that are present in near-Gaussian size distributions in water vapor and moist air. These...

H. R. Carlon

1989-01-01

143

Determination of partition coefficients of diazepam and flurazepam between phosphatidylcholine bilayer vesicles and water by second derivative spectrophotometric method.  

PubMed

Second derivative spectrophotometry allowed the establishment of a simple and accurate method for the determination of partition coefficients of benzodiazepine drugs in a liposome/water system. The absorption spectra of diazepam (DZ) and flurazepam (FZ) in phosphatidylcholine (egg yolk) bilayer vesicle suspensions showed small spectral changes depending on the concentration of phosphatidylcholine vesicles. However, the intense background signals caused by the light scattering of the phosphatidylcholine vesicles made it difficult to yield a correct base line, thus the quantitative spectral data could not be obtained. In the second derivative spectra, the spectral changes were enhanced and three derivative isosbestic points were observed for each drug indicating the entire elimination of the residual background signal effects. The derivative intensity change of each drug (DeltaD) induced by its interaction with phosphatidylcholine bilayers was measured at a specific wavelength. From the relationship between the DeltaD value and the lipid concentration, the molar partition coefficients (K(p)s) of DZ and FZ were calculated and obtained with a good precision of R.S.D below 10%. The fractions of the partitioned DZ and FZ calculated by using the obtained K(p) values agreed well with the experimental values. The results prove that the derivative method can be usefully and easily applied to the determination of partition coefficients of benzodiazepines in the liposomes/water system without any separation procedures. PMID:11275439

Omran, A A; Kitamura, K; Takegami, S; El-Sayed, A A; Abdel-Mottaleb, M

2001-05-01

144

MEASUREMENT OF PARAMETRS OF LASER RADIATION: 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  

NASA Astrophysics Data System (ADS)

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.

Pelivanov, Ivan M.; Barskaya, M. I.; Podymova, N. B.; Khokhlova, Tanya D.; Karabutov, Aleksander A.

2009-09-01

145

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

Microsoft Academic Search

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 970nm and 1200nm 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

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

2008-01-01

146

Vertical Molecular Absorption Coefficient Profiles and Associated Meteorological Data at the High Energy Laser Systems Test Facility for 20 August 1991.  

National Technical Information Service (NTIS)

In support of White Sands Missile Range high energy laser operations for 20 August 1991, the U.S. Army Atmospheric Sciences Laboratory was tasked to calculate simulated molecular absorption coefficient vertical profiles by using the U.S. Air Force Phillip...

F. T. Kantrowitz

1992-01-01

147

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

148

Remote sensing D/H ratios in methane ice: Temperature-dependent absorption coefficients of CH 3D in methane ice and in nitrogen ice  

NASA Astrophysics Data System (ADS)

The existence of strong absorption bands of singly deuterated methane (CH 3D) at wavelengths where normal methane (CH 4) absorbs comparatively weakly could enable remote measurement of D/H ratios in methane ice on outer Solar System bodies. We performed laboratory transmission spectroscopy experiments, recording spectra at wavelengths from 1 to 6 ?m to study CH 3D bands at 2.47, 2.87, and 4.56 ?m, wavelengths where ordinary methane absorption is weak. We report temperature-dependent absorption coefficients of these bands when the CH 3D is diluted in CH 4 ice and also when it is dissolved in N 2 ice, and describe how these absorption coefficients can be combined with data from the literature to simulate arbitrary D/H ratio absorption coefficients for CH 4 ice and for CH 4 in N 2 ice. We anticipate these results motivating new telescopic observations to measure D/H ratios in CH 4 ice on Triton, Pluto, Eris, and Makemake.

Grundy, W. M.; Morrison, S. J.; Bovyn, M. J.; Tegler, S. C.; Cornelison, D. M.

2011-04-01

149

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

PubMed

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

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

2010-01-20

150

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

SciTech Connect

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

Thomas, B.L.

1984-07-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

153

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

154

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

PubMed Central

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.

2013-01-01

155

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

156

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

157

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

NASA Astrophysics Data System (ADS)

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

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

158

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

NASA Astrophysics Data System (ADS)

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

Sharma, Keshav; Adhikari, Narayan P.

2014-04-01

159

Atmospheric Water Absorption and the Water Budget of Terrestrial Isopods (Crustacea, Isopoda, Oniscidea)  

Microsoft Academic Search

Studies of terrestrial isopods (Crustacea, Iso- poda, Oniscidea) have revealed a capacity for active water vapor absorption (WVA) in the taxonomic sections Cri- nocheta and Diplocheta but not in Synocheta. Uptake thresholds in Crinocheta are modest by comparison with other vapor absorbers, but standardized uptake fluxes are among the highest recorded and are probably an adaptive requirement to counter the

JONATHAN C. WRIGHT; JOHN MACHIN

1993-01-01

160

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

PubMed

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

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

2013-09-01

161

Reduction of tetranitromethane by electronically excited aromatics in acetonitrile: Spectra and molar absorption coefficients of radical cations of anthracene, phenanthrene and pyrene  

NASA Astrophysics Data System (ADS)

Room temperature absorption spectra of the long-lived transient species produced by photolysing solutions containing tetranitromethane (TNM) or a TNM/arene mixture have been recorded with a multi-channel spectrophotometer, capable of ?s time resolution and covering a wide spectral range (200-1010 nm). The arene was anthracene ( A), naphthalene ( N), phenanthrene ( ?), or pyrene ( P). In methanol, Arad + , Nrad + and ?rad + disappear within the available time resolution, but all four cations live for tens or hundreds of ?s in acetonitrile; the molar absorption coefficients of Arad + , ?rad + and Prad + in the latter solvent match those of the respective anions in tetrahydrofuran.

Naqvi, K. Razi; Melø, Thor Bernt

2006-09-01

162

Temperature dependence of optical absorption coefficient of 4H- and 6H-SiC from room temperature to 300 °C  

NASA Astrophysics Data System (ADS)

Optical absorption coefficients of 4H- and 6H-SiC were measured at cutoff wavelengths from a value of 0 to 400–500 cm−1 at various temperatures that is from room temperature to 300 °C. The redshift of the absorption edge with increasing temperature was observed. It is caused by a decrease in bandgap energy and a change in phonon occupation with increasing temperature. By considering TA-, LA-, and TO-mode phonon-assisted indirect transitions, the measured data are well fitted using a theoretical model. The obtained parameters are reported.

Watanabe, Naoki; Kimoto, Tsunenobu; Suda, Jun

2014-10-01

163

Studies on the Water Absorption of Bamboo-Epoxy Composites: The Effect of Silane Treatment  

Microsoft Academic Search

The effect of silane treatments on the water absorption properties of bamboo matting reinforced epoxy composites were investigated. Treatments using ?-Aminopropyltriethoxy silane, 3-trimethoxysilylpropyl methacrylate, Vinyltris(2-methoxyethoxy)silane, Bis[3-(triethoxysilyl)propyl] tetrasulfide, 3-aminopropyltrimethoxy silane and n-Octyltrimethoxy silane were carried out to study the water absorption property of the bamboo composites. Water absorption in the composites was studied by long-term immersion and 2 h boiling in distilled

Pradeep K. Kushwaha; Rakesh Kumar

2010-01-01

164

Micropulse water vapor differential absorption lidar: transmitter design and performance.  

PubMed

An all diode-laser-based micropulse differential absorption lidar (DIAL) laser transmitter for tropospheric water vapor and aerosol profiling is presented. The micropulse DIAL (MPD) transmitter utilizes two continuous wave (cw) external cavity diode lasers (ECDL) to seed an actively pulsed, overdriven tapered semiconductor optical amplifier (TSOA). The MPD laser produces up to 7 watts of peak power over a 1 µs pulse duration (7 µJ) and a 10 kHz pulse repetition frequency. Spectral switching between the online and offline seed lasers is achieved on a 1Hz basis using a fiber optic switch to allow for more accurate sampling of the atmospheric volume between the online and offline laser shots. The high laser spectral purity of greater than 0.9996 coupled with the broad tunability of the laser transmitter will allow for accurate measurements of tropospheric water vapor in a wide range of geographic locations under varying atmospheric conditions. This paper describes the design and performance characteristics of a third generation MPD laser transmitter with enhanced laser performance over the previous generation DIAL system. PMID:23187280

Nehrir, Amin R; Repasky, Kevin S; Carlsten, John L

2012-10-22

165

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

E-print Network

, yet with distinct absorption characteristics, distinct temperatures, and distinct lengths. The authors to be investigated. Therefore, properties of an absorber that are relevant to photovoltaic solar energy conversion. There, specific details of the absorption characteristics of the IB absorber are highlighted

Honsberg, Christiana

166

Measurement of partition coefficients for selected polycyclic aromatic hydrocarbons between isolated plant cuticles and water.  

PubMed

Partition coefficients between plant cuticles and water (Kcutw) were measured for 10 selected polycyclic aromatic hydrocarbons (PAHs) to evaluate the sorption capacity of plant cuticular layers for hydrophobic organic chemicals. The partitioning properties of PAHs between cuticles and water were evaluated by using (1) isolated cuticular layers and (2) leaf homogenate. The abaxial and adaxial cuticular layers of Euonymus japonicus were isolated by enzymatic digestion. A third-phase partitioning method using poly(dimethylsiloxane) (PDMS) was used to obtain Kcutw. The Kcutw values for the selected PAHs showed no significant differences between the abaxial and adaxial cuticular layers and ranged between 10(4.1) and 10(7.6). These values are close to or slightly higher than their 1-octanol/water partition coefficient (log Kow), indicating high sorption capacity of plant cuticles. On the contrary, partition coefficients between the lipid tissues of homogenized leaves and water were lower than those obtained using isolated cuticular layers by factors of 3.7-190, which is likely due to the breakdown of lipid layers. This indicates that the sorption of hydrophobic organic chemicals by plant leaves is better evaluated using isolated cuticles and that the sorption potential of plant leaves may be underestimated when leaf homogenates are used. PMID:25038429

Kim, Su-Jin; Lee, Hwang; Kwon, Jung-Hwan

2014-10-01

167

A novel multi?wavelength photoacoustic spectrometer for the measurement of the UV–vis-NIR spectral absorption coefficient of atmospheric aerosols  

Microsoft Academic Search

A multi-wavelength photoacoustic instrument is described, which measures the wavelength dependent optical absorption coefficient (OAC) of soot or soot-containing aerosols in-situ in a range from the ultra-violet to the near-infrared region. The instrument combines a Nd:YAG disc laser (fundamental wavelength 1064nm, harmonics at 532, 355 and 266nm) and four photoacoustic detection cells, each purged with the same aerosol sample flow,

Tibor Ajtai; Ágnes Filep; Martin Schnaiter; Claudia Linke; Marlen Vragel; Zoltán Bozóki; Gábor Szabó; Thomas Leisner

2010-01-01

168

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

2013-06-01

169

The influence of absorption factors on the sensitivity of a virtual room’s sound field to scattering coefficients  

Microsoft Academic Search

Currently there is limited information on what scattering coefficients (SCs) to assign materials in geometrical room acoustic computer models. As a result, room modelers rely on general guidelines and intuition when assigning SCs. How sensitive is the predicted sound field to the user’s choice of scattering coefficients? The sound field’s sensitivity depends on its diffusivity (without SCs); the more diffuse

Lily M. Wang; Jonathan Rathsam

2008-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

171

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

EPA Science Inventory

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

172

Cavity enhanced absorption spectroscopy measurements of pressure-induced broadening and shift coefficients in the ? 1+ ? 3 combination band of ammonia  

NASA Astrophysics Data System (ADS)

Cavity enhanced absorption spectroscopy is performed using an external cavity diode laser operating around 1516 nm. We demonstrate a sensitivity of 6×10-8 cm-1 Hz-1/2 and utilise a simple method to measure pressure-induced broadening and shift coefficients. The broadening and shift coefficients for six gases (helium, neon, argon, xenon, oxygen and nitrogen) have been determined at room temperature for four transitions in the ? 1+ ? 3 combination band of ammonia. Comparisons of the broadening coefficients with previous work in this region, where it exists, show good agreement. The broadening and shift coefficients of nitrogen and oxygen are also in good agreement with calculated values using the Robert and Bonamy theory. Both the broadening and shift coefficients show a clear trend through the rare gases, which can be explained in terms of the varying magnitude of the long range attractive forces operating between the colliding partners. We also demonstrate the application of the Parmenter-Seaver formalism to estimate the potential well depth of the ammonia dimer from the obtained broadening coefficients. The obtained well depth agrees well with theoretical calculations.

Bell, C. L.; Dhib, M.; Hancock, G.; Ritchie, G. A. D.; van Helden, J. H.; van Leeuwen, N. J.

2009-02-01

173

Evaluation of biokinetic coefficients in degradation of oilfield produced water under varying salt concentrations  

Microsoft Academic Search

Biokinetic coefficients were evaluated for a New Mexico oilfield produced water. Total n-alkane removal efficiencies greater than 99% were achieved. Using respirometric techniques for determination of the biokinetic constants, values of 1.37 mg\\/l and 0.136 h?1 were obtained for Ks and ?max, respectively. Evaluation of specific growth rates at various levels of total dissolved solids (TDS) concentration exhibited a distinct

Gilbert T. Tellez; N. Nirmalakhandan; Jorge L. Gardea-Torresdey

1995-01-01

174

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

175

Comparison of reflectance with backscatter and absorption parameters for turbid waters  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

176

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

PubMed

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

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

2014-08-30

177

LEO-LEO OCCULTATIONS MEASURING WATER VAPOR AND TEMPERATURE VIA ABSORPTION  

E-print Network

of water vapor at these altitudes. Utilizing the 22 GHz and the 183 GHz water vapor ab- sorption linesLEO-LEO OCCULTATIONS MEASURING WATER VAPOR AND TEMPERATURE VIA ABSORPTION S. Syndergaard, B. M of water vapor. Water vapor as well as dry air affects the refractivity of the atmosphere

178

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

E-print Network

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

Oklahoma State University

179

Stratum Corneum Damage and ex vivo Porcine Skin Water Absorption – A Pilot Study  

Microsoft Academic Search

A simple ex vivo screening technique would be of interest for mass screening of substances for potential barrier disruptive qualities. Ex vivo water absorption as a marker of skin barrier integrity was studied on pig ear skin. Skin water absorption was quantified by weighing and weight changes were found to reflect prehydration barrier damage. It is suggested that this simple

C. Duch Lynggaard; D. Bang Knudsen; G. B. E. Jemec

2009-01-01

180

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

181

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

182

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

183

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

184

Collisional excitation of water in warm astrophysical media. I. Rate coefficients for rovibrationally excited states  

NASA Astrophysics Data System (ADS)

Context: The interpretation of water line emission from infrared and submillimetre observations requires a detailed knowledge of collisional rate coefficients over a wide range of levels and temperatures. Aims: We attempt to determine rotational and rovibrational rate coefficients for H2O colliding with both H2 and electrons in warm, molecular gas. Methods: Pure rotational rates are derived by extrapolating published data using a new method partly based on the information (phase space) theory of Levine and co-workers. Ro-vibrational rates are obtained using vibrational relaxation data available in the literature and by assuming a complete decoupling of rotation and vibration. Results: Rate coefficients were obtained for the lowest 824 ro-vibrational levels of H2O in the temperature range 200-5000 K. Our data is expected to be accurate to within a factor of ~5 for the highest rates (?10-11 cm3 s-1). Smaller rates, including the ro-vibrational ones, should be generally accurate to within an order of magnitude. As a first application of this data, we show that vibrationally excited water emission observed in evolved stars is expected to be at least partly excited by means of collisions. Tables A.1-A.4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/492/257

Faure, A.; Josselin, E.

2008-12-01

185

An elemental mercury diffusion coefficient for natural waters determined by molecular dynamics simulation.  

PubMed

Mercury is a priority pollutant as its mobility between the hydrosphere and the atmosphere threatens the biosphere globally. The air-water gas transfer of elemental mercury (Hg0) is controlled by its diffusion through the water-side boundary layer and thus by its diffusion coefficient, D(Hg), the value of which, however, has not been established. Here, the diffusion of Hg0 in water was modeled by molecular dynamics (MD) simulation and the diffusion coefficient subsequently determined. Therefore the movement of either Hg(0) or xenon and 1000 model water molecules (TIP4P-Ew) were traced for time spans of 50 ns. The modeled D(Xe) of the monatomic noble gas agreed well with measured data; thus, MD simulation was assumed to be a reliable approach to determine D(Hg) for monatomic Hg(0) as well. Accordingly, Hg(0) diffusion was then simulated for freshwater and seawater, and the data were well-described by the equation of Eyring. The activation energies for the diffusion of Hg0 in freshwater was 17.0 kJ mol(-1) and in seawater 17.8 kJ mol(-1). The newly determined D(Hg) is clearly lower than the one previously used for an oceanic mercury budget. Thus, its incorporation into the model should lead to lower estimates of global ocean mercury emissions. PMID:19534132

Kuss, Joachim; Holzmann, Jörg; Ludwig, Ralf

2009-05-01

186

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

187

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

188

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

PubMed Central

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

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

189

Optical absorption and fluorescence properties of chromophoric dissolved organic matter in natural waters  

Microsoft Academic Search

Complete optical absorption and fluorescence spectra were collected for a diverse suite of 0.2-pm- filtered marine, riverine, and estuarine waters, as well as for colored dissolved organic matter (CDOM) isolated from several of thcsc waters by solid-phase C,, extraction. Absorption and fluorescence parameters for these samples arc reported. For surface waters, variations in the fluorescence quantum yields obtained with 355-

SARAH A. GREEN; NEIL V. BLOUGH

1994-01-01

190

Studies on Water Absorption of Bamboo-Polyester Composites: Effect of Silane Treatment of Mercerized Bamboo  

Microsoft Academic Search

The effect of silane treatments on the water absorption properties of mercerized bamboo matting reinforced polyester composites were investigated. Treatments using ?-Aminopropyltriethoxy silane, 3-trimethoxysilylpropyl methacrylate, Vinyltris(2-methoxyethoxy)silane, Bis[3-(triethoxysilyl)propyl] tetrasulfide, 3-aminopropyltrimethoxy silane and n-Octyltrimethoxy silane were carried out to improve the water resistant property of the bamboo fibers. Water absorption in the composites was studied by long-term immersion and 2 h boiling in

Pradeep K. Kushwaha; Rakesh Kumar

2009-01-01

191

Performance analysis of ammonia absorption GAX cycle for combined cooling and hot water supply modes  

Microsoft Academic Search

An ammonia Generator–Absorber heat eXchange (GAX) absorption cycle with combined cooling and hot water supply modes is developed in this study. This paper proposes new multi-modes GAX cycles which function in three different modes (case 1, case 2 and case 3) of cooling and hot water supply with one hardware (ammonia\\/water GAX absorption heat pump), and finds the best cycle

Chan Woo Park; Junemo Koo; Yong Tae Kang

2008-01-01

192

Recent measurements of the spectral backward-scattering coefficient in coastal waters  

NASA Astrophysics Data System (ADS)

The backward scattering coefficient bb was measured in various coastal waters with fixed-angle backscattering sensors developed by the authors. Measurements were made at four discrete wavelengths covering the spectral range 440 to 675 nm. A power law spectral dependence of bb due to scattering by particles was investigated of the form bbp((lambda) ) equals bbp ((lambda) 0) ((lambda) 0/(lambda) )(gamma , where the superscript p denotes particle scattering and (lambda) is the wavelength. The exponent (gamma) depends on the particle size distribution and composition of particles. Extensive measurements in Monterey Bay, California, showed that 0.1 waters generally below 10 m. For the upper 10 m, 0.7 waters near Panama City, Florida, (gamma) for the upper 10 m was found to be in the range, 0.9 water, 0.9 waters of East Sound, Washington, 0 waters measured.

Maffione, Robert A.; Dana, David R.

1997-02-01

193

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

Microsoft Academic Search

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

Eric Braekevelt; Sheryl A Tittlemier; Gregg T Tomy

2003-01-01

194

Investigation of correlation with the octanol water partition coefficient and the sensitivity of negative-tone molecular resists  

NASA Astrophysics Data System (ADS)

In this paper, we report the investigation of correlation with the octanol water partition coefficient and the sensitivity of negative-tone molecular resists based on calix[4]resorcinarene (CRA) by Electron Beam Lithography (EBL). The sensitivity of negative-tone molecular resists were higher as the value of the Octanol water partition coefficient got smaller. It was confirmed that the octanol water partition coefficient was useful to the guess of sensitivity of negativetone molecular resists. Furthermore, we have developed calix[4]resorcinarenes showing well-defined sub 20nm halfpitch patterns.

Echigo, Masatoshi; Yamakawa, Masako; Ochiai, Yumi; Okada, Yu; Takasuka, Masaaki

2012-03-01

195

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

NASA Astrophysics Data System (ADS)

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 atmospheric field studies have so far yielded inconclusive results. Here we report spectral measurements in the near-infrared around 750 nm in the expected region of the | 0⟨f | 4⟩b|0 ⟩ overtone of the water dimer's hydrogen-bonded OH stretching vibration. The results were obtained using broadband cavity ringdown spectroscopy (BBCRDS), a methodology that allows absorption measurements to be made under controlled laboratory conditions but over absorption path lengths representative of atmospheric conditions. In order to account correctly and completely for the overlapping absorption of monomer molecules in the same spectral region, we have also constructed a new list of spectral data (UCL08) for the water monomer in the 750-20 000 cm-1 (13 ?m-500 nm) range. Our results show that the additional lines included in the UCL08 spectral database provide an improved representation of the measured water monomer absorption in the 750 nm region. No absorption features other than those attributable to the water monomer were detected in BBCRDS experiments performed on water vapour samples containing dimer concentrations up to an order of magnitude greater than expected in the ambient atmosphere. The absence of detectable water dimer features leads us to conclude that, in the absence of significant errors in calculated dimer oscillator strengths or monomer/dimer equilibrium constants, the widths of any water dimer absorption features present around 750 nm are of the order of 100 cm-1 HWHM, and certainly greater than the 25-30 cm-1 HWHM reported in the literature for lower energy water dimer transitions up to 8000 cm-1.

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

2011-05-01

196

Measurements of absorbed heat flux and water-side heat transfer coefficient in water wall tubes  

NASA Astrophysics Data System (ADS)

The tubular type instrument (flux tube) was developed to identify boundary conditions in water wall tubes of steam boilers. The meter is constructed from a short length of eccentric tube containing four thermocouples on the fire side below the inner and outer surfaces of the tube. The fifth thermocouple is located at the rear of the tube on the casing side of the water-wall tube. The boundary conditions on the outer and inner surfaces of the water flux-tube are determined based on temperature measurements at the interior locations. Four K-type sheathed thermocouples of 1 mm in diameter, are inserted into holes, which are parallel to the tube axis. The non-linear least squares problem is solved numerically using the Levenberg-Marquardt method. The heat transfer conditions in adjacent boiler tubes have no impact on the temperature distribution in the flux tubes.

Taler, Jan; Taler, Dawid; Kowal, Andrzej

2011-04-01

197

Determination of the quasi-TE mode (in-plane) graphene linear absorption coefficient via integration with silicon-on-insulator racetrack cavity resonators.  

PubMed

We examine the near-IR light-matter interaction for graphene integrated cavity ring resonators based on silicon-on-insulator (SOI) race-track waveguides. Fitting of the cavity resonances from quasi-TE mode transmission spectra reveal the real part of the effective refractive index for graphene, n(eff) = 2.23 ± 0.02 and linear absorption coefficient, ?(gTE) = 0.11 ± 0.01dB?m(-1). The evanescent nature of the guided mode coupling to graphene at resonance depends strongly on the height of the graphene above the cavity, which places limits on the cavity length for optical sensing applications. PMID:25089481

Crowe, Iain F; Clark, Nicholas; Hussein, Siham; Towlson, Brian; Whittaker, Eric; Milosevic, Milan M; Gardes, Frederic Y; Mashanovich, Goran Z; Halsall, Matthew P; Vijayaraghaven, Aravind

2014-07-28

198

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

PubMed

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

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

2014-12-01

199

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

200

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

Microsoft Academic Search

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

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

2009-01-01

201

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

NASA Technical Reports Server (NTRS)

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

James, W. P.

1971-01-01

202

Measurements of Multicomponent Diffusion Coefficients for Lysozyme Chloride in Water and Aqueous Na$_2$SO$_4$  

E-print Network

This paper presents a diffusion experimental study for ternary lysozyme-Na$_2$SO$_4$-water system, from moderate precipitant concentrations into the supersaturated region and provides a complete set of four diffusion coefficients. These data are important in order to provide accurate models of protein diffusion with applications in growth of protein crystals for X-ray diffraction studies. All three-component mutual-diffusion experiments reported here were performed by Rayleigh interferometry at pH$=4.5$, T$=25^o$ C and at a mean lysozyme concentration (average of top and bottom solution concentrations) of 0.6 mM (8.6 mg/mL). Four experiments, with different combinations of protein and Na$_2$SO$_4$ concentration differences, were performed at each of five mean Na$_2$SO$_4$ concentrations (0.1, 0.25, 0.5, 0.65 and 0.8 M), for a total of 20 experiments. In addition, we have measured dynamic light-scattering diffusion coefficients of the ternary system lysozyme chloride-Na$_2$SO$_4$-water.

Buzatu, D; Buzatu, F D; Albright, J G

2004-01-01

203

Remote sensing of the diffuse attenuation coefficient of ocean water. [coastal zone color scanner  

NASA Technical Reports Server (NTRS)

A technique was devised which uses remotely sensed spectral radiances from the sea to assess the optical diffuse attenuation coefficient, K (lambda) of near-surface ocean water. With spectral image data from a sensor such as the coastal zone color scanner (CZCS) carried on NIMBUS-7, it is possible to rapidly compute the K (lambda) fields for large ocean areas and obtain K "images" which show synoptic, spatial distribution of this attenuation coefficient. The technique utilizes a relationship that has been determined between the value of K and the ratio of the upwelling radiances leaving the sea surface at two wavelengths. The relationship was developed to provide an algorithm for inferring K from the radiance images obtained by the CZCS, thus the wavelengths were selected from those used by this sensor, viz., 443, 520, 550 and 670 nm. The majority of the radiance arriving at the spacecraft is the result of scattering in the atmospheric and is unrelated to the radiance signal generated by the water. A necessary step in the processing of the data received by the sensor is, therefore, the effective removal of these atmospheric path radiance signals before the K algorithm is applied. Examples of the efficacy of these removal techniques are given together with examples of the spatial distributions of K in several ocean areas.

Austin, R. W.

1981-01-01

204

EV-13 Helium Valve Discharge Coefficient Characterization by Continuous Water Flow Test  

NASA Astrophysics Data System (ADS)

In this project, the students of the Suborbital Center of Excellence characterized the discharge coefficient of a modified NASA scientific Balloon valve using a water channel that was designed and built by the students specifically to test this valve. This coefficient is used in the balloon flight models (SINBAD) to predict the helium discharge rates at various altitudes and appropriate helium vent durations. Previous phases of the project subjected the valve to both highly transient and steady air flows resulting in a relatively small range of possible discharge coeffi- cient values that compared well to previous tests of the EV-13 valve. In this test, water is to be used as the working fluid because there will be fewer variables in the equation. Fewer equation variables translate to an error rate smaller than some of the previous test phases. Additionally, the authors present a detailed error/uncertainty analysis, description of the test setup, experimental procedures, calculations, results from previous phases, and literature searches.

Walker, Seth

205

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

Microsoft Academic Search

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

S. Marca Schrap; Manuela Haller; Antoon Opperhuizen

1995-01-01

206

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

207

[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

2012-01-01

208

Heat losses and heat-transfer coefficient of the side walls of the metallic frame of a solar water heater  

SciTech Connect

A method of determining the heat-transfer coefficient of the side walls of a solar water heater with a metal (steel) frame insulated from the heatreceiver by means of a ..pi..-shaped rubber sealing gasket is proposed.

Avezov, R.R.; Serdyuk, V.V.; Urumbaev, A.Kh.

1984-01-01

209

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

PubMed

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

Demars, B O L; Manson, J R

2013-01-01

210

Water absorption and desorption in shuttle ablator and insulation materials  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

211

Measurement of the x-ray mass energy-absorption coefficient of air using 3 keV to 10 keV synchrotron radiation.  

PubMed

For the first time absolute photon mass energy-absorption coefficients of air in the energy range 3 keV to 10 keV have been measured with relative standard uncertainties less than 1%, significantly smaller than those of up to 5% assumed hitherto for calculated data. Monochromatized synchrotron radiation was used to measure both the total radiant energy by means of silicon photodiodes calibrated against a cryogenic radiometer and the fraction of radiant energy that is deposited in dry air by means of a free air ionization chamber. The measured ionization charge was converted into energy absorbed in air by calculated effective W values of photons as a function of their energy based on new measurements of the W values in dry air for electron kinetic energies between 1 keV and 7 keV, also presented in this work. The measured absorption coefficients were compared with state-of-the art calculations and found to agree within 0.7% with data calculated earlier by Hubbell at energies above 4 keV but were found to differ by values up to 2.1% at 10 keV from more recent calculations of Seltzer. PMID:17019029

Büermann, L; Grosswendt, B; Kramer, H-M; Selbach, H-J; Gerlach, M; Hoffmann, M; Krumrey, M

2006-10-21

212

Water absorption, retention and the swelling characteristics of cassava starch grafted with polyacrylic acid.  

PubMed

An important application of starch grafted with copolymers from unsaturated organic acids is the use as water absorbent. Although much research has been published in recent years, the kinetics of water absorption and the swelling behavior of starch based superabsorbents are relatively unexplored. Also, water retention under mechanical strain is usually not reported. Cassava starch was used since it has considerable economic potential in Asia. The gelatinized starch was grafted with acrylic acid and Fenton's initiator and crosslinked with N,N'-methylenebisacrylamide (MBAM). Besides a good initial absorption capacity, the product could retain up to 63 g H2O/g under severe suction. The material thus combines a good absorption capacity with sufficient gel strength. The mathematical analysis of the absorption kinetics shows that at conditions of practical interest, the rate of water penetration into the gel is determined by polymer chain relaxations and not by osmotic driven diffusion. PMID:24528736

Witono, J R; Noordergraaf, I W; Heeres, H J; Janssen, L P B M

2014-03-15

213

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

214

Water vapor continuum: absorption measurements at 350GHz and model calculations  

NASA Astrophysics Data System (ADS)

Absolute absorption rates of pure water vapor and mixtures of water vapor and nitrogen have been measured in the laboratory at 350 GHz. The dependence on pressure and temperature has been obtained. Additionally, a water vapor continuum parameter estimation, taking even the previous laboratory measurements from 150 to 350 GHz into account, is performed.

Kuhn, T.; Bauer, A.; Godon, M.; Buhler, S.; Kunzi, K.

2002-09-01

215

Using the right slope of the 970 nm absorption feature for estimating canopy water content  

Microsoft Academic Search

Canopy water content (CWC) is important for understanding the functioning of terrestrial ecosystems. Biogeochemical processes like photosynthesis, transpiration and net primary production are related to foliar water. The first derivative of the reflectance spectrum at wavelengths corresponding to the left slope of the minor water absorption band at 970 nm was found to be highly correlated with CWC and PROSAIL

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

2009-01-01

216

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

217

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

NASA Technical Reports Server (NTRS)

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

Crisp, D.

1997-01-01

218

Water Partition Coefficients Between Nominally Anhydrous Minerals and Basaltic Melts: Implication on Mantle Melting  

NASA Astrophysics Data System (ADS)

Partitioning of water between peridotite minerals and basaltic magma has a significant influence on the initiation of melting in the mantle and on the rheological structure of the lithosphere. To investigate mineral/melt and mineral/mineral partitioning of H2O applicable to the mantle, we have conducted multiple saturation experiments consisting of hydrous basalt±ol±opx±cpx in a piston-cylinder apparatus at pressures of 1--2 GPa, temperatures of 1230--1380\\deg C and bulk initial water contents of 3.3 to 6.3 wt.%. We measured H2O in melts and minerals (ol, opx, cpx) by SIMS using methods described by [1]. Resulting liquids have 3.1-6.4 wt.% H2O and average mineral/melt partition coefficients as follows: Dol-melt=0.0017±0.0005 (n=9), Dopx-melt=0.019±0.004 (n=8), and Dcpx-melt=0.023±0.005 (n=2). Mineral/mineral partition coefficients are Dol-opx=0.11±0.01 (n=4), Dol-cpx=0.08±0.01 (n=2) and Dcpx-opx=1.4±0.3 (n=1). Observed partition coefficients are reproducible between experiments and systematic variations with pressure, temperature or concentration of H2O are not apparent, possibly because of the relatively small range of pressures and compositions examined. The Dpyroxene-melt increases with the Al2O3 content of the pyroxene due to enhanced solubility of water in Al-bearing pyroxenes. For a peridotite consisting of 58% ol, 30% opx, 10% cpx, and 2% spinel (assumed nominally anhydrous) the calculated bulk sol-liq D is 0.009±0.002 confirming that water is highly incompatible in mantle minerals. Compared to conventional trace elements, water has a behavior similar to Ce, in accordance with studies on natural basaltic glasses (e.g., [2]). If this bulk D is applicable to the deeper parts of the MORB melting regime, then following [3], we can estimate the effect of H2O on peridotite partial melting: for mantle water concentrations of 50--200 ppm, the near-solidus melt would contain 0.6-2.3 wt.% water. Using the data of [4] for ? Hfusion, the freezing point depression is 20--60\\deg C, which corresponds to initiation of melting beneath along ridge geotherms 5--20 km deeper than the anhydrous solidus, somewhat less than previous estimates ( ˜50 km, [5]). For concentrations of 500--1000 ppm H2O along plume geotherms, melting will begin 60--130 km deeper than the dry solidus. References [1] Koga et al. (2003) G3 4,1--20. [2] Michael (1995) EPSL 131, 301--320. [3] Hirschmann et al. (1999) J. Petrol.40, 831--851. [4] Kojitani and Akaogi (1997) EPSL 153, 209--222. [5] Hirth and Kohlstedt (1996) EPSL 144, 93--108.

Aubaud, C. P.; Hauri, E. H.; Hirschmann, M. M.

2004-12-01

219

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

PubMed

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

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

2013-12-01

220

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

SciTech Connect

We construct a rigid-body (5-dimensional) potential-energy surface for the water-hydrogen complex using scaled perturbation theory (SPT). An analytic fit of this surface is obtained, and using this, two minima are found: the global minimum has C{sub 2v} symmetry, with the hydrogen molecule acting as a proton donor to the oxygen atom on water; a local minimum with C{sub s} symmetry has the hydrogen molecule acting as a proton acceptor to one of the hydrogen atoms on water, where the OH bond and H{sub 2} are in a T-shaped configuration. The SPT global and local minima are bound by 1097 {micro}E{sub h} (E{sub h} {approx} 4.359 744 x 10{sup -18} J). Our best estimate of the binding energy, from a complete basis set extrapolation of coupled-cluster calculations, is 1076.1 {micro}E{sub h}. The fitted surface is used to calculate the second cross virial coefficient over a wide temperature range (100-3000 K). Three complementary methods are used to quantify quantum statistical mechanical effects that become significant at low temperatures. We compare our results with experimental data, which are available over a smaller temperature range (230-700 K). Generally good agreement is found, but the experimental data are subject to larger uncertainties.

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

2004-01-08

221

Determining water cloud particle sizes from lidar depolarization measurements and time dependent multiple scattering coefficients  

NASA Technical Reports Server (NTRS)

We present a technique of extracting water cloud particle size information from lidar measurements in conjunction with double scattering calculations. In this presentation, we describe the technique and give examples using data taken with the Air Force Phillips Laboratory's (Geophysics Directorate) low altitude Nd:YAG, elastic backscatter lidar. In a related presentation we describe the double scattering lidar model which we developed for this work. The technique uses simultaneous measurements of two orthogonal linear polarization components of lidar returns from water clouds or other media composed of spherical particles. Any depolarization of the incident lidar radiation backscattered by such a media can only be due to multiple scattering. The amount of depolarization is dependent on the extinction coefficient and the single scatter phase matrix, both of which are functions of position in the medium. The phase matrix is dependent on the index of refraction of the particles and the particle size distribution. Our technique is a modification of a procedure presented in Reference 1. There, particle sizes of water clouds are determined from double scattering calculations together with measurements of radiation scattered from volumes outside the lidar receiver's field of view (which can only be multiply scattered radiation). The methodology of our technique is similar but our 'probe' of the scattering phase function (and thus the particle size distribution) is different.

Garner, R. C.; Koenig, G. G.

1992-01-01

222

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

2012-02-01

223

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

NASA Astrophysics Data System (ADS)

Water has been considered to significantly affect the mantle dynamics. In particular, experimental deformation studies [1-4] claimed that even small amount of water enhanced the creep in olivine by orders of magnitude. However, we note that their results are experimental artifact due to a number of limitations: e.g., unavoidable grain boundary sliding when polycrystalline samples were used; limited ranges of water contents due to the limited pressures; several orders higher stress and strain rate than those in nature. High temperature creep of silicate minerals is controlled by silicon self-diffusion. Therefore, measurement of silicon self-diffusion coefficients (DSi) in minerals, which can be performed without these limitations, is an independent way to study the mantle rheology. In this study, we measured DSi in Mg end-member of olivine, namely, forsterite, as a function of water content (CH2O) across a wide range, and concluded that effect of water on upper mantle rheology is very small. Forsterite single crystals were doped with <1 to ~800 ?g/g of water at 1600 K, 8 GPa using talc+brucite water sources and graphite buffer. The CH2O in the samples were controlled by the ratio of water sources to graphite. The water doped samples were polished, deposited with 500 nm 29Si enriched Mg2SiO4 thin films, and annealed at 8 GPa, 1600 or 1800 K for diffusion with the same proportion of water sources, which successfully made constant values of CH2O during diffusion annealing. The diffusion profiles were obtained by SIMS. CH2O in the samples were determined by FT-IR before and after diffusion, and also examined by SIMS. Our results yield a relationship: DSi ? (CH2O)1/3. This is explained by defect chemistry, where DSi?[VSi????]×[VO??]?(CH2O)2/3×(CH2O)-1/3=(CH2O)1/3 under the charge neutrality condition of [(OH)O?]=2[VMg??] because both Si and O vacancies are needed for Si ions to diffuse. The water contents exponent (1/3) determined in this study is much smaller than 1.2 [5], which was estimated based on deformation experiments. The small water content exponent demonstrates that effect of water on upper mantle rheology is very small in comparing with other factors like temperature, or shear stress. The difference in viscosity of olivine between dry (e.g., ~1 ?g/g of water) and 1000 ?g/g (maximum in upper mantle [6]) is only by a factor of 10. The softening of oceanic lithosphere, which is required to explain the plate motion, cannot be caused by hydration. [1] Karato et al. (1986), JGR 91, 8151-8176. [2] Mei and Kohlstedt (2000a), JGR 105(B9), 21471-21481. [3] Mei and Kohlstedt (2000b), JGR 105(B9), 21457-21469. [4] Jung and Karato (2001), Science 293, 1460-1463. [5] Hirth and Kohlstedt (2003), Geophys. Monogr. Am. Geophys. Union. 138, 83-106. [6] Hirschmann (2006), An. Rev. Earth Planet. Sci. 34, 629-653.

Fei, H.; Wiedenbeck, M.; Yamazaki, D.; Katsura, T.

2012-12-01

224

Effect of an optical pump on the absorption coefficient of Ba0.6Sr0.4TiO3-La(Mg0.5Ti0.5)O3 ceramics in the terahertz range  

NASA Astrophysics Data System (ADS)

The absorption coefficient of 0.4Ba0.6Sr0.4TiO3-0.6La(Mg0.5Ti0.5)O3 ceramic and its tunability under external optical fields are investigated at room temperature by means of terahertz time-domain spectroscopy. Experimental results show that the absorption coefficient of 0.4Ba0.6Sr0.4TiO3-0.6La(Mg0.5Ti0.5)O3 ceramic is approximately 50-500 cm-1 in the frequency range of 0.1-0.8 THz. Application of the optical field leads to an appreciable tuning of dielectric loss, which reaches up to 20.5%. Further theoretical analysis revealed that the variation of absorption coefficient was related to light-induced carriers and OH- absorption in this ceramic.

Wu, Liang; Jiang, Linkun; Xu, Yebin; Ding, Xin; Yao, Jianquan

2014-10-01

225

MEASUREMENT OF DIELECTRIC CONSTANT OF SALINE WATER AND ESTIMATION OFEMISSIVITY AND SCATTERING COEFFICIENT AT DIFFERENT PHYSICAL TEMPERATURESAT MICROWAVE FREQUENCIES  

Microsoft Academic Search

The salinity and the physical temperature of ocean water vary from place to place and with depth of sea. This communication suggests microwave remote sensing of oceanic surface, by measuring dielectric constant of saline water with variable salinity at different physical temperatures using waveguide cell method. The scattering coefficient is estimated using perturbation model of slightly rough surface and emissivity

O. P. N. Call; Dinesh Bohr; Rajesh Vyas

226

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...

227

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.

2011-06-01

228

Measuring the osmotic water permeability coefficient (pf) of spherical cells: isolated plant protoplasts as an example.  

PubMed

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is a simple and very efficient method for the determination of the osmotic water permeability coefficient (Pf) in plant protoplasts, applicable in principle also to other spherical cells such as frog oocytes. The first step of the assay is the isolation of protoplasts from the plant tissue of interest by enzymatic digestion into a chamber with an appropriate isotonic solution. The second step consists of an osmotic challenge assay: protoplasts immobilized on the bottom of the chamber are submitted to a constant perfusion starting with an isotonic solution and followed by a hypotonic solution. The cell swelling is video recorded. In the third step, the images are processed offline to yield volume changes, and the time course of the volume changes is correlated with the time course of the change in osmolarity of the chamber perfusion medium, using a curve fitting procedure written in Matlab (the 'PfFit'), to yield Pf. PMID:25350534

Shatil-Cohen, Arava; Sibony, Hadas; Draye, Xavier; Chaumont, François; Moran, Nava; Moshelion, Menachem

2014-01-01

229

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

PubMed Central

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

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

2013-01-01

230

Mass transfer in SCW extraction molecular diffusion and mass transfer coefficients of ketones and alkenes in sub- and supercritical water  

SciTech Connect

The potential of sub- and supercritical water as extraction solvents has been demonstrated for the (reactive) extraction of coals, used car tires, organic species from residual aqueous solutions, and class selective extraction of organic pollutants with different polarities from solids. In addition, the potential of extraction of coal with supercritical aqueous solutions has been studied. However, physical transport in water at elevated temperature and pressures- and their impact on heterogenous reactions and (reactive) extraction -are not adequately understood. This situation is largely due to the limited data that is available for diffusion in high temperature, high pressure water mixture. Only the molecular diffusion of Iodine ions and hydroquinone in near-critical subcritical water and the self diffusion of coefficient of compressed supercritical water have been reported. In this paper, we present molecular diffusion coefficients of benzophenone, acetone, naphthalene, and anthracene in water at infinite dilution. Pressures ranged from 250 to 500 bar at temperatures ranging from 50{degrees}C to 500{degrees}C resulting in water densities ranging from 1000 to 150 kg/m{sup 3}. Diffusion coefficients were determined by the Taylor-Aris dispersion technique. The effects of increased diffusion on the mass transfer coefficients for emulsions and packed beds were quantified. Molecular division coefficients were 10 to 20 times faster in supercritical water than in water at ambient conditions. Experimental results were correlated with hydrodynamic and kinetic theory. This study and results to be published elsewhere show that diffusion-limited conditions are much more likely to be encountered in supercritical water than is commonly acknowledged.

Goemans, M.G.E.; Gloyna, E.F. [Univ. of Texas, Austin, TN (United States)] [and others

1996-10-01

231

Methods for analysis of selected metals in water by atomic absorption  

USGS Publications Warehouse

This manual describes atomic-absorption-spectroscopy methods for determining calcium, copper, lithium, magnesium, manganese, potassium, sodium, strontium and zinc in atmospheric precipitation, fresh waters, and brines. The procedures are intended to be used by water quality laboratories of the Water Resources Division of the U.S. Geological Survey. Detailed procedures, calculations, and methods for the preparation of reagents are given for each element along with data on accuracy, precision, and sensitivity. Other topics discussed briefly are the principle of atomic absorption, instrumentation used, and special analytical techniques.

Fishman, Marvin J.; Downs, Sanford C.

1966-01-01

232

Saturated flow boiling of water in a narrow channel: time-averaged heat transfer coefficients and correlations  

Microsoft Academic Search

Time-averaged local heat transfer coefficients were measured during flow boiling of water at atmospheric pressure in a vertical channel of rectangular cross-section 2 mm by 1 mm for ranges of mass flux 57–211 kg\\/m2s, heat flux 27–160 kW\\/m2, thermodynamic quality 0–0.3 and inlet subcooling 1–12 K. The heat transfer coefficients were found to increase nearly with the square root of

D. S. Wen; Youyou Yan; D. B. R. Kenning

2004-01-01

233

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

SciTech Connect

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

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

2012-07-01

234

Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune  

E-print Network

Transmission spectroscopy to date has detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain high mean molecular weights, opaque clouds, or scattering hazes in their atmospheres, obscuring our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of HAT-P-11b (~4 Earth radii) from the optical to the infrared. We detected water vapour absorption at 1.4 micrometre wavelength. The amplitude of the water absorption (approximately 250 parts-per- million) indicates that the planetary atmosphere is predominantly clear down to ~1 mbar, and sufficiently hydrogen-rich to exhibit a large scale height. The spectrum is indicative of a planetary atmosphere with an upper limit of ~700 times the abundance of...

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

2014-01-01

235

Temperature and density dependence of the light and heavy water ultraviolet absorption edge  

Microsoft Academic Search

Characteristics of the ultraviolet absorption band edge of high-pressure light and heavy water are reported over the temperature range of 25-400 °C, extending into the supercritical regime. A gradual redshift in the absorption band edge of ?0.6 eV is observed with increasing temperature. This shift cannot be explained by vibrational hot band growth or changes in the degree of Rayleigh

Timothy W. Marin; Kenji Takahashi; David M. Bartels

2006-01-01

236

Temperature and density dependence of the light and heavy water ultraviolet absorption edge  

Microsoft Academic Search

Characteristics of the ultraviolet absorption band edge of high-pressure light and heavy water are reported over the temperature range of 25-400 °C, extending into the supercritical regime. A gradual redshift in the absorption band edge of ~0.6 eV is observed with increasing temperature. This shift cannot be explained by vibrational hot band growth or changes in the degree of Rayleigh

Timothy W. Marin; Kenji Takahashi; David M. Bartels

2006-01-01

237

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

238

Evaluation of Moisture-Related Attenuation Coefficient and Water Diffusion Velocity in Human Skin Using Optical Coherence Tomography  

PubMed Central

In this study, time-resolved optical coherence tomography (OCT) scanning images of the process of water diffusion in the skin that illustrate the enhancement in the backscattered intensities due to the increased water concentration are presented. In our experiments, the water concentration in the skin was increased by soaking the hand in water, and the same region of the skin was scanned and measured with the OCT system and a commercial moisture monitor every three minutes. To quantitatively analyze the moisture-related optical properties and the velocity of water diffusion in human skin, the attenuation coefficients of the skin, including the epidermis and dermis layers, were evaluated. Furthermore, the evaluated attenuation coefficients were compared with the measurements made using the commercial moisture monitor. The results demonstrate that the attenuation coefficient increases as the water concentration increases. Furthermore, by evaluating the positions of center-of mass of the backscattered intensities from OCT images, the diffusion velocity can be estimated. In contrast to the commercial moisture monitor, OCT can provide three-dimensional structural images of the skin and characterize its optical property, which together can be used to observe morphological changes and quantitatively evaluate the moisture-related attenuation coefficients in different skin layers. PMID:23529149

Lee, Cheng-Kuang; Tsai, Meng-Tsan; Chang, Feng-Yu; Yang, Chih-Hsun; Shen, Su-Chin; Yuan, Ouyang; Yang, Chih-He

2013-01-01

239

Determination of cost coefficients of a priority-based water allocation linear programming model - a network flow approach  

NASA Astrophysics Data System (ADS)

This paper presents a method to establish the objective function of a network flow programming model for simulating river-reservoir system operations and associated water allocation, with an emphasis on situations when the links other than demand or storage have to be assigned with nonzero cost coefficients. The method preserves the priorities defined by rule curves of reservoir, operational preferences for conveying water, allocation of storage among multiple reservoirs, and transbasin water diversions. Path enumeration analysis transforms these water allocation rules into linear constraints that can be solved to determine link cost coefficients. An approach to prune the original system into a reduced network is proposed to establish the precise constraints of nonzero cost coefficients, which can then be efficiently solved. The cost coefficients for the water allocation in the Feitsui and Shihmen reservoirs' joint operating system of northern Taiwan was adequately assigned by the proposed method. This case study demonstrates how practitioners can correctly utilize network-flow-based models to allocate water supply throughout complex systems that are subject to strict operating rules.

Chou, F. N.-F.; Wu, C.-W.

2014-05-01

240

Determination of cost coefficients of priority-based water allocation linear programming model - a network flow approach  

NASA Astrophysics Data System (ADS)

This paper presents a method to establish the objective function of a network flow programming model for simulating river/reservoir system operations and associated water allocation, with an emphasis on situations when the links other than demand or storage have to be assigned with nonzero cost coefficients. The method preserves the priorities defined by rule curves of reservoir, operational preferences for conveying water, allocation of storage among multiple reservoirs, and trans-basin water diversions. Path enumeration analysis transforms these water allocation rules into linear constraints that can be solved to determine link cost coefficients. An approach to prune the original system into a reduced network is proposed to establish the precise constraints of nonzero cost coefficients which can then be efficiently solved. The cost coefficients for the water allocation in the Feitsui and Shihmen Reservoirs joint operating system of northern Taiwan was adequately assigned by the proposed method. This case study demonstrates how practitioners can correctly utilize network-flow-based models to allocate water supply throughout complex systems that are subject to strict operating rules.

Chou, F. N.-F.; Wu, C.-W.

2013-12-01

241

Mass-transfer performance of rotating packed beds equipped with blade packings in VOCs absorption into water  

Microsoft Academic Search

This work examined the mass transfer of the rotating packed bed (RPB) equipped with blade packings using VOCs absorption. Ethanol, acetone and ethyl acetate were used as the model VOCs herein. The overall volumetric gas-side mass-transfer coefficient (KGa) for three VOCs absorption was observed to increase with the rotor speed, the gas flow rate and the liquid flow rate. Moreover,

Chia-Chang Lin; Kuo-Shin Chien

2008-01-01

242

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

NASA Technical Reports Server (NTRS)

Clouds strongly modulate radiative transfer processes in the Earth's atmosphere. Studies, which simulate bulk properties of clouds, such as absorption, require methods that accurately account for multiple scattering among individual cloud particles. Multiple scattering processes are well described by MIE-theory, if interacting particles have a spherical shape. This is a good assumption for water droplets. Thus, simulations for water clouds (especially for interactions with solar radiation) usually apply readily available MIE-codes. The presence of different drop-sizes, however, necessitates repetitive calculations for many sizes. The usual representation by a few sizes is likely to miss contributions from densely distributed, sharp resonances. Despite their usually narrow width, integrated over the entire size-spectrum of a cloud droplet distribution, the impact of missed resonances could add up. The consideration of these resonances tends to increase cloud extinction and cloud absorption. This mechanism for a larger (than by MIE-methods predicted) solar absorption has the potential to explain observational evidence of larger than predicted cloud absorption at solar wavelengths. The presentation will address the absorption impact of added resonances for typical properties of water clouds (e.g. drop size distributions, drop concentrations and cloud geometry). Special attention will be given to scenarios with observational evidence of law than simulated solar absorption; particularly if simultaneous measurements of cloud micro- and macrophysical properties are available.

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

2002-01-01

243

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...

244

The Relationship Between the Glass Transition Temperature and Water Vapor Absorption by Poly(vinylpyrrolidone)  

Microsoft Academic Search

Water associated with amorphous solids is known to affect significantly the physical and chemical properties of dosage form ingredients. An analysis of water vapor absorption isotherms of poly(vinylpyrrolidone) measured in this and other laboratories, over the range -40 to 60°C, along with the measurement of the glass transition temperature of poly(vinylpyrrolidone) as a function of water content is reported. It

Cynthia A. Oksanen; George Zografi

1990-01-01

245

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

2012-02-14

246

Accurate Potentiometric Determination of Lipid Membrane–Water Partition Coefficients and Apparent Dissociation Constants of Ionizable Drugs: Electrostatic Corrections  

Microsoft Academic Search

Purpose  Potentiometric lipid membrane–water partition coefficient studies neglect electrostatic interactions to date; this leads to\\u000a incorrect results. We herein show how to account properly for such interactions in potentiometric data analysis.\\u000a \\u000a \\u000a \\u000a Materials and Methods  We conducted potentiometric titration experiments to determine lipid membrane–water partition coefficients of four illustrative\\u000a drugs, bupivacaine, diclofenac, ketoprofen and terbinafine. We then analyzed the results conventionally and with

Mustafa M. A. Elsayed; Ulrich Vierl; Gregor Cevc

2009-01-01

247

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

PubMed

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

Simon, Arthi; Shanmugam, Palanisamy

2013-12-01

248

An Accurate Method for Computing the Absorption of Solar Radiation by Water Vapor  

NASA Technical Reports Server (NTRS)

The method is based upon molecular line parameters and makes use of a far wing scaling approximation and k distribution approach previously applied to the computation of the infrared cooling rate due to water vapor. Taking into account the wave number dependence of the incident solar flux, the solar heating rate is computed for the entire water vapor spectrum and for individual absorption bands. The accuracy of the method is tested against line by line calculations. The method introduces a maximum error of 0.06 C/day. The method has the additional advantage over previous methods in that it can be applied to any portion of the spectral region containing the water vapor bands. The integrated absorptances and line intensities computed from the molecular line parameters were compared with laboratory measurements. The comparison reveals that, among the three different sources, absorptance is the largest for the laboratory measurements.

Chou, M. D.

1980-01-01

249

Rapid determination of octanol-water partition coefficient using vortex-assisted liquid-liquid microextraction.  

PubMed

Vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography (HPLC) is proposed here for the rapid determination of octanol-water partitioning coefficients (Kow). VALLME uses vortex agitation, a mild emulsification procedure, to disperse microvolumes of octanol in the aqueous phase thus increasing the interfacial contact area and ensuring faster partitioning rates. With VALLME, 2min were enough to achieve equilibrium conditions between the octanolic and aqueous phases. Upon equilibration, separation was achieved using centrifugation and the octanolic microdrop was collected and analyzed in a HPLC system. Six model compounds with logKow values ranging between ?0.5 and 3.5 were used during the present investigations. The proposed method produced logKow values that were consistent with previously published values and the recorded uncertainty was well within the acceptable log unit range. Overall, the key features of the proposed Kow determination procedure comprised speed, reliability, simplicity, low cost and minimal solvent consumption. PMID:24468238

Román, Iván P; Mastromichali, Anna; Tyrovola, Konstantina; Canals, Antonio; Psillakis, Elefteria

2014-02-21

250

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

PubMed

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

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

2011-05-01

251

Correlation of membrane/water partition coefficients of detergents with the critical micelle concentration.  

PubMed Central

The membrane/water partition coefficients, K, of 15 electrically neutral (non-charged or zwitterionic) detergents were measured with phospholipid vesicles by using isothermal titration calorimetry, and were compared to the corresponding critical micellar concentrations, cmc. The detergents measured were oligo(ethylene oxide) alkyl ethers (C(m)EO(n) with m = 10/n = 3, 7 and m = 12/n = 3.8); alkylglucosides (octyl, decyl); alkylmaltosides (octyl, decyl, dodecyl); diheptanoylphosphatidylcholine; Tritons (X-100, X-114) and CHAPS. A linear relation between the free energies of partitioning into the membrane and micelle formation was found such that K. CMC approximately 1. The identity K. CMC = 1 was used to classify detergents with respect to their membrane disruption potency. "Strong" detergents are characterized by K. CMC < 1 and solubilize lipid membranes at detergent-to-lipid ratios X(b) < 1 (alkylmaltosides, tritons, heptaethylene glycol alkyl ethers). "Weak" detergents are characterized by K. CMC > 1 and accumulate in the membrane- to detergent-to-lipid ratios X(b) > 1 before the bilayer disintegrates (alkylglucosides, pentaethylene glycol dodecyl ether). PMID:10777739

Heerklotz, H; Seelig, J

2000-01-01

252

A NON-LINEAR STRUCTURE-PROPERTY MODEL FOR OCTANOL-WATER PARTITION COEFFICIENT  

PubMed Central

Octanol-water partition coefficient (Kow) is an important thermodynamic property used to characterize the partitioning of solutes between an aqueous and organic phase and has importance in such areas as pharmacology, pharmacokinetics, pharmacodynamics, chemical production and environmental toxicology. We present a non-linear quantitative structure-property relationship model for determining Kow values of new molecules in silico. A total of 823 descriptors were generated for 11,308 molecules whose Kow values are reported in the PhysProp dataset by Syracuse Research. Optimum network architecture and its associated inputs were identified using a wrapper-based feature selection algorithm that combines differential evolution and artificial neural networks. A network architecture of 50-33-35-1 resulted in the least root-mean squared error (RMSE) in the training set. Further, to improve on single-network predictions, a neural network ensemble was developed by combining five networks that have the same architecture and inputs but differ in layer weights. The ensemble predicted the Kow values with RMSE of 0.28 and 0.38 for the training set and internal validation set, respectively. The ensemble performed reasonably well on an external dataset when compared with other popular Kow models in the literature. PMID:23185102

Yerramsetty, Krishna M.; Neely, Brian J.; Gasem, Khaled A. M.

2012-01-01

253

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

254

Ab initio calculation of the electronic absorption spectrum of liquid water  

NASA Astrophysics Data System (ADS)

The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O-H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

2014-04-01

255

Ab initio calculation of the electronic absorption spectrum of liquid water.  

PubMed

The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O-H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase. PMID:24784291

Martiniano, Hugo F M C; Galamba, Nuno; Cabral, Benedito J Costa

2014-04-28

256

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

257

MEASUREMENT OF PARAMETRS OF LASER RADIATION: Opto-acoustic measurement of the local light absorption coefficient in turbid media: 1. Monte-Carlo simulation of laser fluence distribution at the beam axis beneath the surface of a turbid medium  

NASA Astrophysics Data System (ADS)

A new method for measuring the local light absorption coefficient in turbid media, for example, biological tissues, is proposed. The method is based on the fact that the amplitude of the excited opto-acoustic (OA) signal is proportional to the absorbed laser power density (the product of the light absorption coefficient and the laser fluence) at the medium interface. In the first part of the paper, the influence of the laser beam diameter, the light absorption and reduced scattering coefficients on the maximal amplitude of the laser fluence at the laser beam axis in the near-surface layer of the turbid medium is studied by using the Monte-Carlo simulation. The conditions are predicted under which the amplitude of the OA signal detected in a transparent medium in contact with the scattering medium should remain proportional to the light absorption coefficient of the medium under study, when the scattering coefficient in it changes more than twice. The results of the numerical simulation are used for the theoretical substantiation of the OA method being proposed.

Pelivanov, Ivan M.; Barskaya, M. I.; Podymova, N. B.; Khokhlova, Tanya D.; Karabutov, Aleksander A.

2009-09-01

258

Opto-acoustic measurement of the local light absorption coefficient in turbid media: 1. Monte-Carlo simulation of laser fluence distribution at the beam axis beneath the surface of a turbid medium  

SciTech Connect

A new method for measuring the local light absorption coefficient in turbid media, for example, biological tissues, is proposed. The method is based on the fact that the amplitude of the excited opto-acoustic (OA) signal is proportional to the absorbed laser power density (the product of the light absorption coefficient and the laser fluence) at the medium interface. In the first part of the paper, the influence of the laser beam diameter, the light absorption and reduced scattering coefficients on the maximal amplitude of the laser fluence at the laser beam axis in the near-surface layer of the turbid medium is studied by using the Monte-Carlo simulation. The conditions are predicted under which the amplitude of the OA signal detected in a transparent medium in contact with the scattering medium should remain proportional to the light absorption coefficient of the medium under study, when the scattering coefficient in it changes more than twice. The results of the numerical simulation are used for the theoretical substantiation of the OA method being proposed. (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

259

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

SciTech Connect

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

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

2005-11-01

260

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

E-print Network

Infrared Thermography applied to measurement of Heat transfer coefficient of water in a pipe heated by Joule effect by P. Leblay*, J.-F. Henry**, D. Caron**, D. Leducq*, A. Bontemps*** and L. Fournaison has been developed based on periodic excitation by Joule effect and infrared thermography measurement

Boyer, Edmond

261

The accommodation coefficient of water molecules on ice - cirrus cloud studies at the AIDA simulation chamber  

NASA Astrophysics Data System (ADS)

Cirrus clouds and their impact on the Earth's radiative budget are subjects of current research. The processes governing the growth of cirrus ice particles are central to the radiative properties of cirrus clouds. At temperatures relevant to cirrus clouds, the growth of ice crystals smaller than a few microns in size is strongly influenced by the accommodation coefficient of water molecules on ice, ?ice, making this parameter relevant for cirrus cloud modeling. However, the experimentally determined magnitude of ?ice for cirrus temperatures is afflicted with uncertainties of almost three orders of magnitude, and values for ?ice derived from cirrus cloud data lack significance so far. This has motivated dedicated experiments at the cloud chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) to determine ?ice in the cirrus-relevant temperature interval between 190 K and 235 K under realistic cirrus ice particle growth conditions. The experimental data sets have been evaluated independently with two model approaches: the first relying on the newly developed model SIGMA (Simple Ice Growth Model for determining Alpha), the second one on an established model, ACPIM (Aerosol-Cloud-Precipitation Interaction Model). Within both approaches a careful uncertainty analysis of the obtained ?ice values has been carried out for each AIDA experiment. The results show no significant dependence of ?ice on temperature between 190 K and 235 K. In addition, we find no evidence for a dependence of ?ice on ice particle size or on water vapor supersaturation for ice particles smaller than 20 ?m and supersaturations of up to 70%. The temperature-averaged and combined result from both models is ?ice = 0.7-0.5+0.3, which implies that ?ice may only exert a minor impact on cirrus clouds and their characteristics when compared to the assumption of ?ice =1. Impact on prior calculations of cirrus cloud properties, e.g., in climate models, with ?ice typically chosen in the range 0.2-1 is thus expected to be negligible. In any case, we provide a well-constrained ?ice which future cirrus model studies can rely on.

Skrotzki, J.; Connolly, P.; Schnaiter, M.; Saathoff, H.; Möhler, O.; Wagner, R.; Niemand, M.; Ebert, V.; Leisner, T.

2013-04-01

262

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

SciTech Connect

The key technical barrier to using water/lithium bromide (LiBr) as the working fluid in aircooled absorption chillers and absorption heat-pump systems is the risk of crystallization when the absorber temperature rises at fixed evaporating pressure. This article reviews various crystallization control technologies available to resolve this problem: chemical inhibitors, heat and mass transfer enhancement methods, thermodynamic cycle modifications, and absorption system-control strategies. Other approaches, such as boosting absorber pressure and J-tube technology, are reviewed as well. This review can help guide future efforts to develop water/LiBr air-cooled absorption chillers and absorption heatpump systems.

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

2011-01-01

263

Experimental determination of the absorption cross-section and molar extinction coefficient of CdSe and CdTe nanowires.  

PubMed

Absorption cross-sections and corresponding molar extinction coefficients of solution-based CdSe and CdTe nanowires (NWs) are determined. Chemically grown semiconductor NWs are made via a recently developed solution-liquid-solid (SLS) synthesis, employing low melting Au/Bi bimetallic nanoparticle "catalysts" to induce one-dimensional (1D) growth. Resulting wires are highly crystalline and have diameters between 5 and 12 nm as well as lengths exceeding 10 microm. Narrow diameters, below twice the corresponding bulk exciton Bohr radius of each material, place CdSe and CdTe NWs within their respective intermediate to weak confinement regimes. Supporting this are solution linear absorption spectra of NW ensembles showing blue shifts relative to the bulk band gap as well as structure at higher energies. In the case of CdSe, the wires exhibit band edge emission as well as strong absorption/emission polarization anisotropies at the ensemble and single-wire levels. Analogous photocurrent polarization anisotropies have been measured in recently developed CdSe NW photodetectors. To further support fundamental NW optical/electrical studies as well as to promote their use in device applications, experimental absorption cross-sections are determined using correlated transmission electron microscopy, UV/visible extinction spectroscopy, and inductively coupled plasma atomic emission spectroscopy. Measured CdSe NW cross-sections for 1 microm long wires (diameters, 6-42 nm) range from 6.93 x 10(-13) to 3.91 x 10(-11) cm2 at the band edge (692-715 nm, 1.73-1.79 eV) and between 3.38 x 10(-12) and 5.50 x 10(-11) cm2 at 488 nm (2.54 eV). Similar values are obtained for 1 microm long CdTe NWs (diameters, 7.5-11.5 nm) ranging from 4.32 x 10(-13) to 5.10 x 10(-12) cm2 at the band edge (689-752 nm, 1.65-1.80 eV) and between 1.80 x 10(-12) and 1.99 x 10(-11) cm2 at 2.54 eV. These numbers compare well with previous theoretical estimates of CdSe/CdTe NW cross-sections far to the blue of the band edge, having order of magnitude values of 1.0 x 10(-11) cm2 at 488 nm. In all cases, experimental NW absorption cross-sections are 4-5 orders of magnitude larger than those for corresponding colloidal CdSe and CdTe quantum dots. Even when volume differences are accounted for, band edge NW cross-sections are larger by up to a factor of 8. When considered along with their intrinsic polarization sensitivity, obtained NW cross-sections illustrate fundamental and potentially exploitable differences between 0D and 1D materials. PMID:17165978

Protasenko, Vladimir; Bacinello, Daniel; Kuno, Masaru

2006-12-21

264

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

NASA Astrophysics Data System (ADS)

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

Kiatkamjornwong, Suda; Chomsaksakul, Wararuk; Sonsuk, Manit

2000-10-01

265

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...

266

Time-resolved refractive index and absorption mapping of light-plasma filaments in water  

E-print Network

By means of a quantitative shadowgraphic method, we performed a space-time characterization of the refractive index variation and transient absorption induced by a light-plasma filament generated by a 100 fs laser pulse in water. The formation and evolution of the plasma channel in the proximity of the nonlinear focus were observed with a 23 fs time resolution.

Minardi, Stefano; Tatarakis, Michael; Tamosauskas, Arnaud Couairon Gintaras; Piskarskas, Rimtautas; Dubietis, Audrius; Di Trapani, Paolo

2007-01-01

267

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

E-print Network

connects the aqueous solution to the heme site. Ferric horseradish peroxidase has an absorption band at 640, the protein was incorporated into trehalose/sucrose glasses and the hydration of the sugar glasses was varied are narrower for the protein in glycerol/water (glass transition at 150 K) than in trehalose/sucrose (glass

Sharp, Kim

268

Estimation of Concentration and Bonding Environment of Water Dissolved in Common Solvents Using Near Infrared Absorptivity.  

National Technical Information Service (NTIS)

Integrated near infrared (NIR) absorbance has been used to determine the absorptivity of the v2+v3 combination band of the asymmetric stretch (v2) and the bending vibration (v3) for water in several organic solvents. Absorptivitiy measured in this way is ...

B. Dickens, S. H. Dickens

1999-01-01

269

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

Microsoft Academic Search

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

D. P Bentz; K. K Hansen

2000-01-01

270

Computer simulation of a lithium bromide-water absorption heat pump for temperature boosting  

Microsoft Academic Search

A computer-simulation model has been developed to predict the performance of an absorption heat pump for temperature boosting of low-grade heat. The model simulated a single-stage, lithium bromide-water system currently being constructed. Te effects of waste-heat temperature, cooling-water temperature, and solution circulation rate were investigated. The temperature boost and delivered capacity increased almost linearly with an increase in the waste-heat

G. Grossman; K. W. Childs

1983-01-01

271

Investigation on thermal accommodation coefficient and soot absorption function with two-color Tire-LII technique in rich premixed flames  

NASA Astrophysics Data System (ADS)

Although the two-color laser-induced incandescence technique (2C-LII) has proved to be a significant tool for soot diagnostics, many efforts are still required to gain a whole understanding of the chemical and physical processes involved. Time-resolved two-color LII measurements are carried out in a rich ethylene/air premixed flame at different heights above the burner and by changing the laser fluence. The prompt LII at two wavelengths and the corresponding soot incandescence temperature are obtained at different stages of the soot growth and under different laser irradiations. The decay rate of the LII signals, as a method for soot sizing, is investigated at different laser fluence. The time-resolved LII curves, obtained in the low laser fluence regime, are analyzed by a numerical simulation, available on the web. By considering the gas/particle initial temperature obtained with thermocouple measurements and by knowing soot particle diameter with previous TEM and extinction/scattering measurements, information about soot parameters, such as absorption function and thermal accommodation coefficient are obtained. The presence of the so-called young or mature soot along the flame height is strictly related to different optical and heat-exchange properties necessary to fit all the experimental data available.

Maffi, S.; De Iuliis, S.; Cignoli, F.; Zizak, G.

2011-08-01

272

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

E-print Network

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

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

2006-01-01

273

Determination of the attenuation coefficients by visible and ultraviolet radiation in heavy water  

Microsoft Academic Search

A long-path-length transmission cell has been used to measure the attenuation coefficients of purified HâO and DâO at various wavelengths between 250 and 580 nm. The principles governing the procedures and corrections for various sources of light attenuation in the transmission cell components are discussed. Detailed chemical histories of the HâO and DâO samples are given. The measured attenuation coefficients

L. P. Boivin; W. F. Davidson; R. S. Storey; D. Sinclair; E. D. Earle

1986-01-01

274

Determination of water absorption and water holding capacities of different soil mixtures with MINIDRAIN system to enhance the plant growth  

NASA Astrophysics Data System (ADS)

Soil water holding capacity is the amount of water that a given soil can hold against the force of gravity. Soil texture and organic matter are the key components that determine soil water holding capacity. Soils with smaller particle sizes, such as silt and clay have larger surface area can hold more water compared to sand which has large particle sizes which results in smaller surface area. A study report showed that 1% increase in soil humus will result in a 4% increase in stored soil water (Morris, 2004) and 1 part humus holds 4 parts of water (Wheeler and Ward, 1998). Therefore, the more humus that can be added to the soil, the greater the water holding capacity of the soil. As the level of organic matter increases in a soil, the water holding capacity also increases due to the affinity of organic matter for water. The water holding capacity of the soil is determined by the amount of water held in the soil sample vs. the dry weight of the sample. MINIDRAIN is a patented system made of geo-fabric (fleece) or combination of geosynthetics and humus. MINIDRAIN and vegetation nets developed by the company ÖKO-TEX (Linz, Austria) will improve the distribution of water and air in the soils, increase the growth of vegetation and reduce the soil erosion. Depending on the physical configuration, there are four different combinations of MINIDRAIN systems developed by ÖKO-TEX. a) Geotextile (fleece) strips of different sizes (e.g. 5x10x250 mm) b) Net formed strips (drainage nets) of different sizes c) Multilayer geotextile mats with humus, seeds or compost of different sizes (e.g. 10x30x200 mm) d) Multilayer geotextile net formed mats with humus, seeds or compost This paper describes the experimental results of the water absorption and water holding capacity of different forms of MINIDRAIN under different soil mixes. In this experiment, potting soil, coarse sand and LECA (Light weight clay aggregates) balls are mixed with different proportion of MINIDRAIN systems and the water absorption and water holding capacities are measured. A comparison of the results for an optimal combination of soil and MINIDRAIN system has also been made. The results show that, the soil mix with MINIDRAIN system with multilayer mats (with humus) have highest water absorption and water holding capacity among the tested soil mix combinations.

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

2014-05-01

275

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

276

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

E-print Network

Polarizable interaction potential for water from coupled cluster calculations. II. Applications-pol interaction potential for the water dimer was used to predict properties of the dimer and of liquid water and of bulk water, one needs to know water's force field, i.e., the interaction potential. This potential can

277

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

Code of Federal Regulations, 2012 CFR

...analytical method, dissociation constant, water solubility, and hydrolysis...tested must not be water insoluble (mass concentration...affect the results. Dissociation or association...solutions in place of water should be...

2012-07-01

278

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

SciTech Connect

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

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

2011-03-01

279

Absorption and fluorescence properties of chromophoric dissolved organic matter: implications for the monitoring of water quality in a large subtropical reservoir.  

PubMed

The development of techniques for real-time monitoring of water quality is of great importance for effectively managing inland water resources. In this study, we first analyzed the absorption and fluorescence properties in a large subtropical reservoir and then used a chromophoric dissolved organic matter (CDOM) fluorescence monitoring sensor to predict several water quality parameters including the total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), dissolved organic carbon (DOC), and CDOM fluorescence parallel factor analysis (PARAFAC) components in the reservoir. The CDOM absorption coefficient at 254 nm (a(254)), the humic-like component (C1), and the tryptophan-like component (C3) decreased significantly along a gradient from the northwest to the lake center, northeast, southwest, and southeast region in the reservoir. However, no significant spatial difference was found for the tyrosine-like component (C2), which contributed only four marked peaks. A highly significant linear correlation was found between the a(254) and CDOM concentration measured using the CDOM fluorescence sensor (r (2)?=?0.865, n?=?76, p?absorption coefficient measured in the laboratory. Significant correlations were also found between the CDOM concentration and TN, TP, COD, DOC, and the maximum fluorescence intensity of C1, suggesting that the real-time monitoring of CDOM concentrations could be used to predict these water quality parameters and trace the humic-like fluorescence substance in clear aquatic ecosystems with DOC <2 mg/L and total suspended matter (TSM) concentrations <15 mg/L. These results demonstrate that the CDOM fluorescence sensor is a useful tool for on-line water quality monitoring if the empirical relationship between the CDOM concentration measured using the CDOM fluorescence sensor and the water quality parameters is calibrated and validated. PMID:25053284

Liu, Xiaohan; Zhang, Yunlin; Shi, Kun; Zhu, Guangwei; Xu, Hai; Zhu, Mengyuan

2014-12-01

280

Role of iron and organic carbon in mass-specific light absorption by particulate matter from Louisiana coastal waters  

E-print Network

Role of iron and organic carbon in mass-specific light absorption by particulate matter from Louisiana coastal waters Margaret L. Estapa,a,b,1,* Emmanuel Boss,a Lawrence M. Mayer,b and Collin S absorption measurements could be designed to monitor water-column iron mineral transport and transformation

Boss, Emmanuel S.

281

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

PubMed Central

Plant secondary metabolites (SMs) are pervasive in animal foods and potentially influence feeding behavior, interspecies interactions, and the distribution and abundance of animals. Some of the major classes of naturally occurring SMs in plants include many water-soluble compounds in the molecular size range that could cross the intestinal epithelium via the paracellular space by diffusion or solvent drag. There are differences among species in paracellular permeability. Using Middle Eastern rodent and avian consumers of fruits containing SMs, we tested the hypothesis that avian species would have significantly higher paracellular permeability than rodent species. Permeability in intact animals was assessed using standard pharmacological methodology to measure absorption of two radiolabeled, inert, neutral water-soluble probes that do not interact with intestinal nutrient transporters, L-arabinose (Mr?=?150.1 Da) and lactulose (Mr?=?342.3 Da). We also measured absorption of labeled 3-O-methyl-D-glucose (3OMD-glucose; Mr?=?194.2 Da), which is a nonmetabolized analogue of D-glucose that is passively absorbed through the paracellular space but also transported across the enterocyte membranes. Most glucose was absorbed by all species, but arabinose fractional absorption (f) was nearly three times higher in birds (1.03±0.17, n?=?15 in two species) compared to rodents (0.37±0.06, n?=?10 in two species) (P<0.001). Surprisingly, the apparent rates of absorption in birds of arabinose exceeded those of 3OMD-glucose. Our findings are in agreement with previous work showing that the paracellular pathway is more prominent in birds relative to nonflying mammals, and suggests that birds may be challenged by greater absorption of water-soluble, dietary SMs. The increased expression of the paracellular pathway in birds hints at a tradeoff: the free energy birds gain by absorbing water-soluble nutrients passively may be offset by the metabolic demands placed on them to eliminate concomitantly absorbed SMs. PMID:22389702

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

2012-01-01

282

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

USGS Publications Warehouse

A method has been developed for the accurate determination of 0.1-1 ??g of silver per liter of water. The method permits stabilization of silver in water without loss to container walls. Optimum conditions have been established for the complete recovery of silver from water with an anion-exchange column, for quantitative elution of silver from the resin, and for measurement of silver by atomic absorption spectrophotometry after chelation with ammonium pyrrolidine dithiocarbamate and extraction of the chelate with MIBK. Silver in the 1-10 ??g 1 range can be determined by extraction without pre-concentration on an ion-exchange resin. ?? 1969.

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

1969-01-01

283

A New Approach on Estimation of Solubility and n-octanol/water Partition Coefficient for Organohalogen Compounds  

PubMed Central

The aqueous solubility (logW) and n-octanol/water partition coefficient (logPOW) are important properties for pharmacology, toxicology and medicinal chemistry. Based on an understanding of the dissolution process, the frontier orbital interaction model was suggested in the present paper to describe the solvent-solute interactions of organohalogen compounds and a general three-parameter model was proposed to predict the aqueous solubility and n-octanol/water partition coefficient for the organohalogen compounds containing nonhydrogen-binding interactions. The model has satisfactory prediction accuracy. Furthermore, every item in the model has a very explicit meaning, which should be helpful to understand the structure-solubility relationship and may be provide a new view on estimation of solubility. PMID:19325840

Gao, Shuo; Cao, Chenzhong

2008-01-01

284

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

Microsoft Academic Search

A Quantitative Structure–Property Relationship (QSPR) analysis and study of polycyclic aromatic hydrocarbons (PAHs) is presented. Three physicochemical properties related to their environmental impact are studied: boiling point (bp), octanol–water partition coefficient (logKow) and retention time index (RI) for reversed-phase liquid chromatography analysis. The geometry of all PAHs were optimized by the semi-empirical method AM1 and used to calculate thermodynamic, electronic,

Fabiana Alves de Lima Ribeiro; Márcia Miguel Castro Ferreira

2003-01-01

285

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

PubMed

Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain atmospheres with high mean molecular weights (little hydrogen), opaque clouds or scattering hazes, reducing our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of the exoplanet HAT-P-11b (which has a radius about four times that of Earth) from the optical wavelength range to the infrared. We detected water vapour absorption at a wavelength of 1.4 micrometres. The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e). The spectrum is indicative of a planetary atmosphere in which the abundance of heavy elements is no greater than about 700 times the solar value. This is in good agreement with the core-accretion theory of planet formation, in which a gas giant planet acquires its atmosphere by accreting hydrogen-rich gas directly from the protoplanetary nebula onto a large rocky or icy core. PMID:25254473

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

2014-09-25

286

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

NASA Astrophysics Data System (ADS)

Transmission spectroscopy has so far detected atomic and molecular absorption in Jupiter-sized exoplanets, but intense efforts to measure molecular absorption in the atmospheres of smaller (Neptune-sized) planets during transits have revealed only featureless spectra. From this it was concluded that the majority of small, warm planets evolve to sustain atmospheres with high mean molecular weights (little hydrogen), opaque clouds or scattering hazes, reducing our ability to observe the composition of these atmospheres. Here we report observations of the transmission spectrum of the exoplanet HAT-P-11b (which has a radius about four times that of Earth) from the optical wavelength range to the infrared. We detected water vapour absorption at a wavelength of 1.4 micrometres. The amplitude of the water absorption (approximately 250 parts per million) indicates that the planetary atmosphere is predominantly clear down to an altitude corresponding to about 1 millibar, and sufficiently rich in hydrogen to have a large scale height (over which the atmospheric pressure varies by a factor of e). The spectrum is indicative of a planetary atmosphere in which the abundance of heavy elements is no greater than about 700 times the solar value. This is in good agreement with the core-accretion theory of planet formation, in which a gas giant planet acquires its atmosphere by accreting hydrogen-rich gas directly from the protoplanetary nebula onto a large rocky or icy core.

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

2014-09-01

287

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

NASA Astrophysics Data System (ADS)

This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. Pacific Northwest Laboratory (PNL) researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH4(+)). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

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

1995-05-01

288

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

SciTech Connect

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

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

1995-05-01

289

Experimental measurement of variations in the optical reflection coefficient of water-magnetic liquid interface in an electric field, wave motion, and surface instability  

NASA Astrophysics Data System (ADS)

A variation in the reflection coefficient of an interface of two liquids (water and magnetic liquid) in the presence of an electric field is experimentally studied. An increase in the reflection coefficient of the interface is demonstrated. A surface instability of the water-magnetic liquid interface, the wave motion at the interface, and wave interference are observed.

Chekanov, V. V.; Kandaurova, N. V.; Chekanov, V. S.

2014-09-01

290

Improved Water Level Forecasting Performance by Using Optimal Steepness Coefficients in an Artificial Neural Network  

Microsoft Academic Search

Developing water level forecasting models is essential in water resources management and flood prediction. Accurate water\\u000a level forecasting helps achieve efficient and optimum use of water resources and minimize flooding damages. The artificial\\u000a neural network (ANN) is a computing model that has been successfully tested in many forecasting studies, including river flow.\\u000a Improving the ANN computational approach could help produce

Muhammad Sulaiman; Ahmed El-Shafie; Othman Karim; Hassan Basri

2011-01-01

291

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

Microsoft Academic Search

Orchard olive transpiration, soil water status and stomatal response in relation to water deficit were investigated to clarify mechanisms of tree water uptake and stomatal control to improve the irrigation scheduling of low-density olive trees of cv. Cordovil grown in typical Mediterranean environment of Southern Portugal. Trees were subject to three irrigation treatments. Treatment A received 100% of crop evapotranspiration

F. L. Santos

2008-01-01

292

Water pair potential of near spectroscopic accuracy. I. Analysis of potential surface and virial coefficients  

E-print Network

Water pair potential of near spectroscopic accuracy. I. Analysis of potential surface and virial pair potential for water was generated by fitting 2510 interaction energies computed by the use with experiment. Features of the water dimer potential energy surface have been analyzed using SAPT-5s. Average

293

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

Microsoft Academic Search

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

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

2005-01-01

294

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

E-print Network

. HE PHASZ BEHAVIOR ARD ABSORPTION SPECTRA. OF THE TER1MRY SYSTEN COBALTOUS CHLORIDE-WATER-AGZTOIJITRILE A Thesis by JEFFREY LOVZTT BOBBIT'1 Submitted to the Graduate College of the Texas A&N University in Partial fulfillment... CONCIUSION Interpretation of Zxoerimental Results Summary and Suggestions for Further Study APP 'NDICES ~ 1 3 8 11 12 14 15 15 24 36 36 39 41 Cobaltous Chloride-Nater Solutions Prepared for Phase Diagram Determination . Cobaltous Chloride...

Bobbitt, Jeffrey Lovett

2012-06-07

295

Relationship of Kernel Size to Flour Water Absorption for Canada Western Red Spring Wheat  

Microsoft Academic Search

Cereal Chem. 77(3):286-292 Canada Western Red Spring (CWRS) wheat exhibits consistent posi- tive relationships between kernel weight and farinograph and baking water absorption. These relationships are sufficiently robust to be statistically significant (P < 0.05) for historical Canadian Grain Commission harvest survey data generated one year apart for 17 years, and for historical data on individual cultivars in advanced Canadian

B. C. Morgan; J. E. Dexter; K. R. Preston

2000-01-01

296

Sublimation coefficient of water ice under simulated cometary-like conditions  

Microsoft Academic Search

In papers dealing with evolution of cometary nuclei it is commonly assumed that the coefficients of sublimation ?s and condensation ?c of vapour are both equal to one. The experimental investigation of ice samples under simulated cometary-like conditions (Kossacki, K.J., Kömle, N.I., Leliwa-Kopysty?ski, J., Kargl, G., 1997. Thermal and structural evolution of cometary subsurface layer: selfconsistent model and experimental verification.

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

1999-01-01

297

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

NASA Astrophysics Data System (ADS)

The extraction of caffeine with aliphatic alcohols C3-C9 from aqueous solutions in the presence of a salting-out agent (ammonium sulfate) is studied. Quantitative characteristics of extraction are calculated: the distribution coefficients ( D) and the degree of recovery ( R, %). Relations are found between log D of caffeine and the length of the hydrocarbon radical in the alcohol molecule, along with certain physicochemical properties of the extragents.

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

2012-11-01

298

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

PubMed

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

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

1993-08-20

299

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

NASA Astrophysics Data System (ADS)

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

Santos, F. L.

2008-12-01

300

Moisture absorption characteristics of the Orbiter thermal protection system and methods used to prevent water ingestion  

NASA Technical Reports Server (NTRS)

The Space Shuttle Orbiter's silica tile Thermal Protection System (TPS) is beset by the moisture absorption problems inherently associated with low density, highly porous insulation systems. Attention is presently given to the comparative success of methods for the minimization and/or prevention of water ingestion by the TPS tiles, covering the development of water-repellent agents and their tile application techniques, flight test program results, and materials improvements. The use of external films for rewaterproofing of the TPS tiles after each mission have demonstrated marginal to unacceptable performance. By contrast, a tile interior waterproofing agent has shown promise.

Schomburg, C.; Dotts, R. L.; Tillian, D. J.

1983-01-01

301

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

Microsoft Academic Search

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

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

302

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

USGS Publications Warehouse

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

Fishman, M.

1977-01-01

303

Human skin binding and absorption of contaminants from ground and surface water during swimming and bathing  

SciTech Connect

Contaminants exist in ground and surface water. Human skin has the capacity to bind and then absorb these contaminants into the body during swimming and bathing. Powdered human stratum corneum will bind both lipid-soluble (alachlor, polychlorinated biphenyls (PCBs), benzene) and water-soluble (nitroaniline) chemicals. In vitro (Human skin) and in vivo (Rhesus monkey) studies show that these chemicals readily distribute into skin, and then some of the chemical is absorbed into the body. Linearity in binding and absorption exists for nitroaniline over a 10-fold concentration range. Multiple exposure to benzene is at least cumulative. Binding and adsorption can be significant for exposures as short as 30 minutes, and will increase with time. Adsorption with water dilution increased for alachlor, but not for dinoseb. Soap reversed the partitioning of alachlor between human stratum corneum and water. The PCBs could be removed from skin by soap and water for up to 3 hours and the decontamination potential decreased, due to continuing skin absorption. The model that in vitro and in vivo systems used should permit easy estimation of this area of extensive human exposure effect on risk assessment. 5 refs., 9 tabs.

Wester, R.C.; Maibach, H.I. (California Univ., San Francisco (USA))

1989-10-01

304

Mass transfer of SCWO processes: Molecular diffusion and mass transfer coefficients of inorganic nitrate species in sub- and supercritical water  

SciTech Connect

Molecular diffusion coefficients of lithium-, sodium-, potassium-, cesium-, calcium-, and strontium nitrate in subcritical water were determined by analysis of Taylor dispersion profiles. Pressures ranged from 300 to 500 bar at temperatures ranging from 25{degrees}C to 300{degrees}C. The reported diffusion values were determined at infinite dilution. Molecular diffusion coefficients were 10 to 20 times faster in near-critical subcritical water than in water at ambient temperature and pressure (ATP). These findings implied that the diffusion rates were more liquid like than they were gas like, hence experimental results were correlated with diffusion models for liquids. The subcritical diffusion data presented in this work, and supercritical diffusion results published elsewhere were correlated with hydrodynamic diffusion equations. Both the Wilke-Chang correlation and the Stokes-Einstein equation yielded predictions within 10% of the experimental results if the structure of the diffusing species could be estimated. The effect of the increased diffusion rates on mass transfer rates in supercritical water oxidation applications was quantified, with emphasis on heterogeneous oxidation processes. This study and results published elsewhere showed that diffusion limited conditions are much more likely to be encountered in SCWO processes than commonly acknowledged.

Goemans, M.G.E.; Gloyna, E.F. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering; Buelow, S.J. [Los Alamos National Lab., NM (United States)

1996-04-01

305

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

NASA Technical Reports Server (NTRS)

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

Nurge, Mark A.; Perusich, Stephen A.

2010-01-01

306

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

NASA Astrophysics Data System (ADS)

Water vapor is one of the most significant constituents of the atmosphere because of its role in cloud formation, precipitation, and interactions with electromagnetic radiation, especially its absorption of longwave infrared radiation. Some details of the role of water vapor and related feedback mechanisms in the Earth system need to be characterized better if local weather, global climate, and the water cycle are to be understood. Water vapor profiles are currently obtained with several remote sensing techniques, such as microwave radiometers, passive instruments like the Atmospheric Emitted Radiance Interferometer (AERI) and Atmospheric Infrared Sounder (AIRS), and Raman lidar. Each of these instruments has some disadvantage, such as only producing column-integrated water vapor amounts or being large, overly customized, and costly, making them difficult to use for deployment in networks or onboard satellites to measure water vapor profiles. This thesis work involved the design, construction, and testing of a highly-tunable Differential Absorption Lidar (DIAL) instrument utilizing an all-semiconductor transmitter. It was an attempt to take advantage of semiconductor laser technology to obtain range-resolved water vapor profiles with an instrument that is cheaper, smaller, and more robust than existing field instruments. The eventual goal of this project was to demonstrate the feasibility of this DIAL instrument as a candidate for deployment in multi-point networks or satellite arrays to study water vapor flux profiles. This new DIAL instrument transmitter has, for the first time in any known DIAL instrument, a highly-tunable External Cavity Diode Laser (ECDL) as a seed laser source for two cascaded commercial tapered amplifiers. The transmitter has the capability of tuning over a range of ˜17 nm to selectively probe several available water vapor absorption lines, depending on current environmental conditions. This capability has been called for in other recent DIAL experiments. Tests of the DIAL instrument to prove the validity of its measurements are presented. Initial water vapor profiles, taken in the Bozeman, MT, area, were taken, analyzed, and compared with co-located radiosonde measurements. Future improvements and directions for the next generation of this DIAL instrument are discussed.

Obland, Michael Drew

307

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

NASA Technical Reports Server (NTRS)

An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and greater than 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less than 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.; Ponsardin, Patrick; Hueser, Alene W.

1994-01-01

308

Absorption of water and solute from glucose-electrolyte solutions in the human jejunum: effect of citrate or betaine.  

PubMed

The inclusion in oral rehydration solutions of solutes that are actively co-transported with sodium has been suggested as a means of increasing the effect of glucose on water absorption by the small intestine. Using a modified perfusion system we have examined water and solute absorption in the normal human intestine from two effervescent glucose-electrolyte solutions, containing either citrate or betaine hydrochloride, and compared the absorption rates with those from a commonly used bicarbonate-containing oral rehydration solution. Absorption of citrate (355 +/- 87 mumol/cm/h) and betaine (313 +/- 125 mumol/cm/h) occurred from the respective solutions. The inclusion of 46 mmol/l citrate or 36 mmol/l betaine in effervescent oral rehydration solutions had no effect on water or solute absorption. PMID:2595270

Leiper, J B; Maughan, R J

1989-11-01

309

Experimental study of diffusion coefficients of water through the collagen: apatite porosity in human trabecular bone tissue.  

PubMed

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

Marinozzi, Franco; Bini, Fabiano; Quintino, Alessandro; Corcione, Massimo; Marinozzi, Andrea

2014-01-01

310

Relation between 183 GHz Water Vapor Line and Water Continuum Absorption Measured with FTS  

NASA Astrophysics Data System (ADS)

ve carried out Fourier Transform Spectrometer (FTS) measurements of the millimeter and submillimeter-wave (100-1500 GHz or 3 mm - 200 micron) atmospheric opacity at Pampa la Bola, 4800 m above sea level in northern Chile on September 1997 and June 1998. Correlations between 220 GHz opacities and those of the center of submillimeter-wave windows were obtained using the entire data set, and good correlations were obtained except for the periods affected by the liquid water opacity component. We succeeded to separate the total opacity to water vapor and liquid water opacity components. The separated water vapor opacity component shows good correlation with the 183 GHz pure water vapor line opacity, which is also covered in the measured spectra, but the liquid water opacity component shows no correlation. Since the submillimeter-wave opacity is merely affected by the liquid water component, it may be better to use the submillimeter-wave opacity for the phase correction.

Matsushita, S.; Matsuo, H.

311

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

SciTech Connect

Drinking-water treatment residuals (WTRs) present a low-cost geosorbent for As-contaminated waters and soils. Previous work has demonstrated the high affinity of WTRs for As, but data pertaining to the stability of sorbed As is missing. Sorption/desorption and X-ray absorption spectroscopy (XAS), both XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) studies, were combined to determine the stability of As sorbed by an Fe-based WTR. Arsenic(V) and As(III) sorption kinetics were biphasic in nature, sorbing <90% of the initial added As (15,000 mg kg{sup -1}) after 48 h of reaction. Subsequent desorption experiments with a high P load (7500 mg kg{sup -1}) showed negligible As desorption for both As species, approximately <3.5% of sorbed As; the small amount of desorbed As was attributed to the abundance of sorption sites. XANES data showed that sorption kinetics for either As(III) or As(V) initially added to solution had no effect on the sorbed As oxidation state. EXAFS spectroscopy suggested that As added either as As(III) or as As(V) formed inner-sphere mononuclear, bidentate complexes, suggesting the stability of the sorbed As, which was further corroborated by the minimum As desorption from the Fe-WTR.

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

2009-06-03

312

Lipid nanoparticles with no surfactant improve oral absorption rate of poorly water-soluble drug.  

PubMed

A pharmacokinetic study was performed in rats to evaluate the oral absorption ratios of nanoparticle suspensions containing the poorly water-soluble compound nifedipine (NI) and two different types of lipids, including hydrogenated soybean phosphatidylcholine and dipalmitoylphosphatidylglycerol. NI-lipid nanoparticle (LN) suspensions with a mean particle size of 48.0 nm and a zeta potential of -57.2 mV were prepared by co-grinding combined with a high-pressure homogenization process. The oral administration of NI-LN suspensions to rats led to a significant increase in the NI plasma concentration, and the area under the curve (AUC) value was found to be 108 min ?g mL?¹, indicating a 4-fold increase relative to the NI suspensions. A comparison of the pharmacokinetic parameters of the NI-LN suspensions with those of the NI solution prepared using only the surfactant polysorbate 80 revealed that although the AUC and bioavailability (59%) values were almost identical, a rapid absorption rate was still observed in the NI-LN suspensions. These results therefore indicated that lipid nanoparticles prepared using only two types of phospholipid with a mean particle size of less than 50 nm could improve the absorption of the poorly water-soluble drug. PMID:23624178

Funakoshi, Yuka; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

2013-07-15

313

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

SciTech Connect

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

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

2013-10-10

314

Changes on image texture features of breakfast flakes cereals during water absorption.  

PubMed

Normally breakfast cereal flakes are consumed by pouring them into a bowl and covering them with fresh or cold milk. During this process the liquid uptake causes changes in the surface and internal matrix of breakfast cereals that influence texture and integrity. Some breakfast cereal as flakes have a translucent structure that could provide information about the solid matrix and air cells and how they change during liquid absorption. The objective of the study was to assess the image texture changes of corn flakes and frosted flakes during water absorption at 5, 15 and 25?°C, employing 11 image feature textures extracted from grey-level co-occurrence matrix and grey-level run length matrix (at three directions) and to relate the fractal dimension (FD) of images with rupture force (RF) reduction during soaking of both flakes at 5?°C. The most relevant result from principal component analysis calculated with a matrix of 54 (soaking times)?×?22 (texture features), shows that it was possible to distinguish an isolated group consisting of different soaking times at the same water temperature in each breakfast cereal flakes evaluated, corroborating that superficial liquid imbibition is important during the liquid absorption process when flakes are soaked. Furthermore, standardized FD could be related to RF in the period when samples tend to search for an equilibrium state. PMID:23345324

Medina, Wenceslao T; Quevedo, Roberto A; Aguilera, José M

2013-02-01

315

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

NASA Technical Reports Server (NTRS)

Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

1991-01-01

316

Volatilization of ethylene dibromide from water  

USGS Publications Warehouse

Overall mass-transfer coefficients for the volatilization of ethylene dibromide from water were measured simultaneously with the oxygen absorption coefficient in a laboratory stirred tank. Coefficients were measured as a function of mixing conditions in the water for two windspeeds. The ethylene dibromide mass-transfer coefficient depended on windspeed; the ethylene dibromide liquid-film coefficient did not, in agreement with theory. A constant relation existed between the liquid-film coefficients for ethylene dibromide and oxygen.

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

1987-01-01

317

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

Microsoft Academic Search

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. 84Sr and 86Sr. 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

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

2006-01-01

318

Effects of casein and fat content on water self-diffusion coefficients in casein systems: a pulsed field gradient nuclear magnetic resonance study.  

PubMed

The water self-diffusion coefficients in casein matrixes were measured using a pulsed field gradient spin-echo nuclear magnetic resonance technique (PFG-SE NMR). The dependence of the water self-diffusion coefficient on the casein concentration and the aqueous phase composition is reported in both a rehydrated native phosphocaseinate dispersion and a concentrated casein retentate. A model has been proposed to explain the different behavior of the water self-diffusion coefficient in the two casein systems. This model demonstrates that the water self-diffusion cannot be simply explained by the water content only. So, taking into account the specific effect of each constituent of the aqueous dispersing phase, the water self-diffusion reduction induced by the casein micelle can be modeled. The effect of fat on the water self-diffusion coefficients was investigated. Anhydrous milk fat-reconstituted retentate samples were used in order to estimate the obstruction effect of fat globules in the modeling process. The dependence of the self-diffusion coefficient of water on the fat and casein content is reported. A general model included the effect of the aqueous phase composition, and the obstruction effects of casein micelles and fat globules were proposed. This model was validated for water self-diffusion coefficients in industrial fatty retentates. PMID:15186127

Métais, Angélique; Cambert, Mireille; Riaublanc, Alain; Mariette, François

2004-06-16

319

Atmospheric Pre-Corrected Differential Absorption Techniques to Retrieve Columnar Water Vapor: Theory and Simulations  

NASA Technical Reports Server (NTRS)

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

Borel, Christoph C.; Schlaepfer, Daniel

1996-01-01

320

Enhanced reverse saturable absorption and optical limiting properties in a protonated water-soluble porphyrin  

NASA Astrophysics Data System (ADS)

Nonlinear optical properties of water-soluble porphyrin 5,10,15,20-Tetrakis (1-methyl-4-pyridinio) porphyrin tetra (p-toluenesulfonate) (TMPyP), protonated TMPyP ({{TMPyPH}}_{2}^{2+}), TMPyP film with the gelatin matrix (TMPyP/Gelatin) were investigated by the open-aperture Z-scan technique in the nanosecond regime. Results show that {{TMPyPH}}_{2}^{2+} exhibits a larger ratio of excited state absorption cross-section to that of the ground state and enhanced reverse saturable absorption properties compared with TMPyP and TMPyP/Gelatin. {{TMPyPH}}_{2}^{2+} also shows the superior optical limiting performance, even better than the benchmark material C60 and the multi-walled carbon nanotubes (MWNTs) dispersion.

Zhang, Xiao-Liang; Chen, Xu-Dong; Li, Xiao-Chun; Ying, Cui-Feng; Liu, Zhi-Bo; Tian, Jian-Guo

2013-05-01

321

Theoretical analysis of ammonia-water absorption cycles for refrigeration and space conditioning systems  

NASA Astrophysics Data System (ADS)

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 by way of the rectifier, absorber, and condenser. In a heat pump, the same equipment is used with the heat being dispersed into the space to be heated. Block diagrams are provided of the basic absorption cycle and a model is constructed from heat and mass balance equations and the equations of state for a NH3-H2O cycle system. System simulation then consists of the simultaneous solution of a set of algebraic nonlinear equations and using the Newton-Raphson method to iterate for implicit solutions in each operational mode.

Kaushik, S. C.; Bhardwaj, S. C.

1982-09-01

322

Parameterization of water component absorption in an inland eutrophic lake and its seasonal variability: a case study in Lake Taihu  

Microsoft Academic Search

Water spectral absorption characteristics of eutrophic lakes are largely different from those of ocean and coastal waters. We therefore studied them with the aim of establishing an analytical model for inland water colour, to be used in remote sensing. Field measurements were carried out on 16 and 17 August 2006 (summer), 5 and 6 November 2006 (winter), and 29 and

Deyong Sun; Yunmei Li; Qiao Wang; Chengfeng Le; Changchun Huang; Lizhen Wang

2009-01-01

323

Comment on "A theoretical framework for quantitatively characterizing sound field diffusion based on scattering coefficient and absorption coefficient of walls" [J. Acoust. Soc. Am. 128, 1140-1148 (2010)] (L).  

PubMed

The relationship between the acoustic scattering characteristics of materials and the degree of diffusion in enclosed acoustic spaces has recently attracted considerable research attention. Hanyu [J. Acoust. Soc. Am. 128(3), 1140-1148 (2010)] introduced a theoretical framework, in which the diffusion time in an enclosure is expressed as a function of a material's average scattering coefficient. In this letter, a modification of this theory is proposed. The decay process of the sound energy through scattering is divided into discrete sub-processes, specifically, a purely scattering process, and alternating scattering and specular reflections. The behavior of each process is examined for different scattering coefficients. PMID:23297877

Omoto, Akira

2013-01-01

324

Robust superhydrophobic/superoleophilic sponge for effective continuous absorption and expulsion of oil pollutants from water.  

PubMed

With the growth of oil production and transportation, there is greater potential for accidental oil spills. Here we fabricated a robust superhydrophobic and superoleophilic carbon nanotube/poly(dimethylsiloxane)-coated polyurethane sponge for the continuous absorption and expulsion of oils and organic solvents from water surfaces. When applied in conjunction with a vacuum system, this sponge could separate great amounts of oils-up to 35000 times its own weight-from water in a one-step process and could also separate surfactant-free water-in-oil emulsions with high efficiency (oil purity: >99.97 wt %), making it a promising candidate material for use in oil-spill cleanups. PMID:24032484

Wang, Chih-Feng; Lin, Sheng-Jhih

2013-09-25

325

Standard test method for water absorption of core materials for structural sandwich constructions  

SciTech Connect

This method covers the determination of the relative rate of absorption of water by various types of core materials when immersed. The method is intended to apply to the testing of all types of core materials, including honeycomb structures, wood, cellulated materials, resin-impregnated reinforcing materials, etc. but does not apply to loose mineral fillers. The test specimen shall be in the form of a square 7.62 cm (3 in.) in length by 7.62 cm (3 in.) in width by the thickness of the material. The dimensions shall be measured to an accuracy of +-0.5 percent. Three specimens are weighed individually and conditioned as prescribed before immersion in a container of distilled water maintained at a temperature of 23 +- 3/sup 0/C. At the end of 24 hour, specimens are removed from the water, wiped dry, weighed and calculations are made from data.

Not Available

1980-01-01

326

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

NASA Astrophysics Data System (ADS)

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

Takei, Toshitaka; Saito, Kiyoshi; Kawai, Sunao

327

Assessment of satellite derived diffuse attenuation coefficients and euphotic depths in south Florida coastal waters  

EPA Science Inventory

Optical data collected in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010 were used to evaluate products derived with three bio-optical inversion algorithms applied to MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. Th...

328

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

329

Micellar interactions in water-in-oil microemulsions. 2. Light scattering determination of the second virial coefficient  

SciTech Connect

Both the intensity and the autocorrelation function of the light scattered by water-in-oil (W/O) microemulsions have been studied. The investigated microemulsions were formed from water, dodecane, sodium dodecyl sulfate, and pentanol or hexanol or heptanol. Micellar size and virial coefficients were extracted from experimental data. The data evidence that interactions in these systems mainly depend on alcohol chain length. They are strongly attractive in microemulsions containing pentanol and much less in hexanol and heptanol systems. The intermicellar potential presented in paper 1 allows one to interpret the scattering results and provides an approach for the understanding of the variations of the B values; the agreement between theory and experiment is very good.

Brunetti, S.; Roux, D.; Bellocq, A.M.; Fourche, G.; Bothorel, P.

1983-03-17

330

Simulation model of a single-stage lithium bromide-water absorption cooling unit  

NASA Technical Reports Server (NTRS)

A computer model of a LiBr-H2O single-stage absorption machine was developed. The model, utilizing a given set of design data such as water-flow rates and inlet or outlet temperatures of these flow rates but without knowing the interior characteristics of the machine (heat transfer rates and surface areas), can be used to predict or simulate off-design performance. Results from 130 off-design cases for a given commercial machine agree with the published data within 2 percent.

Miao, D.

1978-01-01

331

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

332

Extraction of Thermodynamic Data from Ternary Diffusion Coefficients of Lysozyme Chloride in Water and Aqueous Na$_2$SO$_4$  

E-print Network

This paper presents, for ternary lysozyme-Na$_2$SO$_4$-water system, the thermodynamic data extracted from the measured values of four ternary diffusion coefficients and the Onsager reciprocal relations. The calculation for derivatives of solute chemical potentials with respect to solute molar concentrations was made using the method presented in \\cite{1}. This method is applicable to systems in which the molar concentration of one solute is very small compared to that of the other, like in our case. The approach is illustrated for the lysozyme chloride-Na$_2$SO$_4$-water system at 25$^o$ C, pH 4.5 and at 0.6 mM (8.6 mg/mL) lysozyme chloride and 0.1, 0.25, 0.5, 0.65, and 0.8 M Na$_2$SO$_4$ concentrations. The calculated solute chemical potential derivatives were used to compute the protein cation charge approximately. We also compute the diffusion Onsager coefficients $(L_{ij})_o$ for each composition at pH 4.5.

Buzatu, D; Buzatu, F D; Albright, J G

2004-01-01

333

MASS TRANSFER COEFFICIENTS FOR A NON-NEWTONIAN FLUID AND WATER WITH AND WITHOUT ANTI-FOAM AGENTS  

SciTech Connect

Mass transfer rates were measured in a large scale system, which consisted of an 8.4 meter tall by 0.76 meter diameter column containing one of three fluids: water with an anti-foam agent, water without an anti-foam agent, and AZ101 simulant, which simulated a non-Newtonian nuclear waste. The testing contributed to the evaluation of large scale mass transfer of hydrogen in nuclear waste tanks. Due to its radioactivity, the waste was chemically simulated, and due to flammability concerns oxygen was used in lieu of hydrogen. Different liquids were used to better understand the mass transfer processes, where each of the fluids was saturated with oxygen, and the oxygen was then removed from solution as air bubbled up, or sparged, through the solution from the bottom of the column. Air sparging was supplied by a single tube which was co-axial to the column, the decrease in oxygen concentration was recorded, and oxygen measurements were then used to determine the mass transfer coefficients to describe the rate of oxygen transfer from solution. Superficial, average, sparging velocities of 2, 5, and 10 mm/second were applied to each of the liquids at three different column fill levels, and mass transfer coefficient test results are presented here for combinations of superficial velocities and fluid levels.

Leishear, R.

2009-09-09

334

Multi-system repeatability and reproducibility of apparent diffusion coefficient measurement using an ice-water phantom  

PubMed Central

Purpose Quantitative quality control procedures were sought to evaluate technical variability in multi-center measurements of the diffusion coefficient of water as a prerequisite to use of the biomarker apparent diffusion coefficient (ADC) in multi-center clinical trials. Materials and Methods A uniform data acquisition protocol was developed and shared with 18 participating test sites along with a temperature-controlled diffusion phantom delivered to each site. Usable diffusion weighted imaging data of ice water at 5 b-values were collected on 35 clinical MRI systems from 3 vendors at 2 field strengths (1.5 and 3T) and analyzed at a central processing site. Results Standard deviation of bore-center ADCs measured across 35 scanners was <2%; error range: ?2% to +5% from literature value. Day-to-day repeatability of the measurements was within 4.5%. Intra-exam repeatability at the phantom center was within 1%. Excluding one outlier, inter-site reproducibility of ADC at magnet isocenter was within 3%, though variability increased for off-center measurements. Significant (>10%) vendor-specific and system-specific spatial non-uniformity ADC bias was detected for the off-center measurement that was consistent with gradient non-linearity. Conclusion Standardization of DWI protocol has improved reproducibility of ADC measurements and allowed identifying spatial ADC non-uniformity as a source of error in multi-site clinical studies. PMID:23023785

Malyarenko, Dariya; Galban, Craig J.; Londy, Frank J.; Meyer, Charles R.; Johnson, Timothy D.; Rehemtulla, Alnawaz; Ross, Brian D.; Chenevert, Thomas L.

2012-01-01

335

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

SciTech Connect

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

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

2007-08-01

336

Polychlorinated biphenyl sorption by soils: Measurement of soil-water partition coefficients at equilibrium  

Microsoft Academic Search

The sorption of PCB congeners 24? (lUPAC number 8), 22?55? (52) and 22?44?55? (153) by eight soils differing in their organic carbon content (2.3 to 0.2% by Wt.) and expandable clay mineral content (17 to 53 % by wt.) has been investigated for 0.1 g\\/L soil-water suspensions. The time to reach sorption equilibrium, i.e. sorption-diffusion equilibrium, for a highly aggregated

Don C. Girvin; Al J. Scott

1997-01-01

337

Water use, crop coefficients, and irrigation management criteria for camelina production in arid regions  

Microsoft Academic Search

Camelina sativa (L.) Crantz is an oilseed crop touted as being suitable for production in the arid southwestern USA. However, because any\\u000a significant development of the crop has been limited to cooler, rain-fed climate-areas, information and guidance for managing\\u000a irrigated-camelina are lacking. This study measured the crop water use of a November-through-April camelina crop in Arizona\\u000a using frequent measurements of

D. J. Hunsaker; A. N. French; T. R. Clarke; D. M. El-Shikha

2011-01-01

338

Gini coefficient to assess equity in domestic water supply in the Yellow River  

Microsoft Academic Search

Yellow River, is designated as “the cradle of Chinese civilization” and played a key role not only in the country’s economic\\u000a development but also in the historic and cultural identity of the Chinese people. With the rapid economic development and\\u000a population growth, water demand for industry and households has increased significantly in the Yellow River basin; this has\\u000a caused an

Xiao-jun Wang; Jian-yun Zhang; Shamsuddin Shahid; Amgad ElMahdi; Rui-min He; Xin-gong Wang; Mahtab Ali

2012-01-01

339

Bioaccumulation Patterns Of PCBs In A Temperate, Freshwater Food Web And Their Relationshop To The Octanol-Water Partition Coefficient (Presentation)  

EPA Science Inventory

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

340

Prediction of ecotoxicological behavior of chemicals: relationship between n-octanol/water partition coefficient and bioaccumulation of organic chemicals by alga Chlorella  

SciTech Connect

The bioaccumulation potential of organic chemicals by the green alga Chlorella fusca was determined. A quantitative relationship was found to exist between the lipophilicity (n-octanol/water partition coefficient) of the chemicals and the bioaccumulation factor.

Geyer, H.; Politzki, G.; Freitag, D.

1984-01-01

341

Particulate and dissolved spectral absorption on the continental shelf of the southeastern United States  

Microsoft Academic Search

Visible absorption spectra of particulate and dissolved materials were characterized on the continental shelf off the southeastern United States (the South Atlantic Bight), emphasizing cross-shelf and seasonal variability. A coastal front separates turbid coastal waters from clearer and seasonal variability. A coastal front separates turbid coastal waters from clearer midshelf waters. Spatial and seasonal patterns were evident in absorption coefficients

James R. Nelson; Sonia Guarda

1995-01-01

342

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

343

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

NASA Astrophysics Data System (ADS)

Besides the absorption by roots from the soil substrate, it has long been known that plants exhibit alternative water-absorption strategies, particularly in drought-prone environments. For many tropical epiphytic orchids, air moisture can be absorbed directly by aerial roots. Some conifers are also found to utilize air moisture by foliar absorption during the summer fog season. However, few studies have been carried out on the atmospheric water vapor absorption by shallow-rooted desert plants. We conducted experiments in desert-oasis ecotone and investigated the effects of dew absorbed by three kinds of shallow-rooted seedlings on net photosynthesis rate, as well as on other water relations variables. Three kinds of typical shallow-rooted desert species (Bassia dasyphylla, Salsola collina and Corispermum declinatum) have been chosen and potted. Each species were subjected to contrasting watering regimes (normal and deficient) and different air moisture conditions (having dew and having no dew) for 10 weeks. Net photosynthesis rate was measured on six occasions during the study. Other water relations variables (midday shoot water potential, relative water content, stomatal conductance) were also measured. Under the dew conditions, average net photosynthesis rate, shoot water potential, leaf relative water content and stomatal conductance increased, with greater responses observed for plants subjected to a deficient watering regime than for well-watered plants. These results indicated dew occurred in arid region could be utilized through foliar absorption by some shallow-rooted plants, and for the shallow-rooted plants, the presence of dew could significantly relieve the deficit of water in water-stressed regime.

Fang, Jing

2014-05-01

344

D2 sticking coefficient and desorption rate on various forms of water ice films under interstellar conditions  

NASA Astrophysics Data System (ADS)

Gas-grain interactions play a key role in the formation of molecular hydrogen in the ISM. An experimental facility named FORMOLISM (Molecular Formation in the Interstellar Medium) has recently been developed in our laboratory in order to investigate the catalytic role played by the grain in the chemical reaction producing H2 in conditions similar to the interstellar medium. A differentially pumped atomic beam of H or D is directed to surface sample which can be cooled down to 8K, in the centre of an ultra high vacuum chamber (<10-10 mBar). Temperature-Programmed Desorption experiments (TPD) can be performed and the desorbing molecules can be selectively probed in their individual (v, J) levels, thanks to the (2+1) Resonance Enhanced Multi-photon Ionisation (REMPI) method. Ions are detected by using a Time-Of-Flight mass spectrometer. Our experiment gives access to fast reactions mechanisms that can not be probed in conventional TPD experiments. REMPI coupling with TOF detection and atomic dosing can be performed simultaneously. In order to determine H and H2 interaction on water ice surfaces, we are conducting a detailed study of D2 adsorbed on different forms of water ice films using both TPD and REMPI techniques. The ice morphology is controlled by changing vapour deposition temperature and subsequent annealing. Variations of D2 sticking coefficients and desorption rate with surface temperature are compared in high density amorphous water ice, and low density amorphous water ice of different porosity.

Amiaud, L.; Baouche, S.; Dulieu, F.; Fillion, J.-H.; Momeni, A.; Lemaire, J.-L.

2004-12-01

345

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

PubMed

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

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

2012-11-01

346

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

E-print Network

The x-ray absorption spectra of water and ice are calculated with a many-body approach for electron-hole excitations. The experimental features, including the small effects of temperature change in the liquid, are quantitatively reproduced from molecular configurations generated by ab-initio molecular dynamics. The spectral difference between the solid and the liquid is due to two major short range order effects. One, due to breaking of hydrogen bonds, enhances the pre-edge intensity in the liquid. The other, due to a non-bonded molecular fraction in the first coordination shell, affects the main spectral edge in the conversion of ice to water. This effect may not involve hydrogen bond breaking as shown by experiment in high-density amorphous ice.

Wei Chen; Xifan Wu; Roberto Car

2009-09-21

347

Differential Absorption Measurements of Atmospheric Water Vapor with a Coherent Lidar at 2050.532 nm  

NASA Technical Reports Server (NTRS)

Wind and water vapor are two major factors driving the Earth's atmospheric circulation, and direct measurement of these factors is needed for better understanding of basic atmospheric science, weather forecasting, and climate studies. Coherent lidar has proved to be a valuable tool for Doppler profiling of wind fields, and differential absorption lidar (DIAL) has shown its effectiveness in profiling water vapor. These two lidar techniques are generally considered distinctly different, but this paper explores an experimental combination of the Doppler and DIAL techniques for measuring both wind and water vapor with an eye-safe wavelength based on a solid-state laser material. Researchers have analyzed and demonstrated coherent DIAL water vapor measurements at 10 micrometers wavelength based on CO2 lasers. The hope of the research presented here is that the 2 gm wavelength in a holmium or thulium-based laser may offer smaller packaging and more rugged operation that the CO2-based approach. Researchers have extensively modeled 2 um coherent lasers for water vapor profiling, but no published demonstration is known. Studies have also been made, and results published on the Doppler portion, of a Nd:YAG-based coherent DIAL operating at 1.12 micrometers. Eye-safety of the 1.12 micrometer wavelength may be a concern, whereas the longer 2 micrometer and 10 micrometer systems allow a high level of eyesafety.

Koch, Grady J.; Dharamsi, Amin; Davis, Richard E.; Petros, Mulugeta; McCarthy, John C.

1999-01-01

348

Changes of color and water-absorption of Hungarian porous limestone due to biomineralization  

NASA Astrophysics Data System (ADS)

Bacteria induced calcium carbonate precipitation nowadays is a widely examined process being a possible alternative for traditional stone conservation methods. While research has been mostly limited to laboratory measurements, application connected, further in situ experiments should be performed in order to evaluate the applicability of the method. In our experiment, several bio-based treating compounds were compared, which have already been analyzed in different laboratories. Method for the treatment was based on the treatment of a French research group, and the compounds were applied on Hungarian porous limestone slabs, in situ. For inoculation bacteria strains Bacillus cereus and Myxococcus xanthus were used, and non-inoculated compounds were also analyzed. After the treatment, specimens were analyzed by means of discoloration effect, water absorption and migration characteristics. Almost all the treating compounds gave favorable or acceptable results for the examined properties, comparing to the properties measured in the non-cured state. Measurements on the chromatic- and on the water absorption aspects gave significant results, while further measurements are running for the more exact evaluation of the migration characteristics, i.e. effective migration depth and wetted volume.

Juhász, P.; Kopecskó, K.

2013-12-01

349

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

E-print Network

The optical properties of ice in the far infrared are important for models of protoplanetary and debris disks. In this report we derive a new set of data for the absorption (represented by the imaginary part of the refractive index $\\kappa$) of crystalline water ice in this spectral range, including a detailed inspection of the temperature dependence, which had not been done in such detail before. We measured the transmission of three ice layers with different thickness at wavelengths $\\lambda=45...1000$ microns at temperatures $\\vartheta = 10...250$ K. We found a change in the spectral dependence of $\\kappa$ at a wavelength of $175 \\pm 6$ microns. At shorter wavelengths, $\\kappa$ exhibits a constant flat slope and no significant temperature dependence. Long-ward of that wavelength, the slope gets steeper and has a clear, approximately linear temperature dependence. This change in the behaviour is probably caused by a characteristic absorption band of water ice. The measured data were fitted by a power-law mo...

Reinert, Caroline; Krivov, Alexander; Löhne, Torsten; Mohr, Pierre

2014-01-01

350

Infrared absorption by pure CO2 near 3340 cm-1: Measurements and analysis of collisional coefficients and line-mixing effects at subatmospheric pressures  

NASA Astrophysics Data System (ADS)

High resolution Fourier transform spectra of the 21102-00001 band of 12C16O2 near 3340 cm-1 have been recorded and analyzed to extract isolated-line intensities and collisional parameters, and first-order line-mixing coefficients. Voigt, hard-collision Rautian and Sobel?man, and quadratic-speed-dependent Voigt profiles have been used. The line-mixing coefficients measured for the three branches have also been evaluated using an Energy-Corrected Sudden approach employing a symmetric metric in the Liouville space. These coefficients compare very favorably with the experimental results and estimations with an algorithm available in the literature. Results of straightforward ECS-modeling of complete band shapes have been compared to the recorded spectra and future improvements of this model required at subatmospheric pressures have been outlined.

Daneshvar, L.; Földes, T.; Buldyreva, J.; Vander Auwera, J.

2014-12-01

351

Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation  

NASA Technical Reports Server (NTRS)

A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

Namkoong, D.

1976-01-01

352

Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation  

NASA Technical Reports Server (NTRS)

A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

Namkoong, D.

1976-01-01

353

IEEE TRANSACTIONS ON ADVANCED PACKAGING, VOL. 30, NO. 3, AUGUST 2007 551 Experimental Analysis of the Water Absorption  

E-print Network

of the Water Absorption Effects on RF/mm-Wave Active/Passive Circuits Packaged in Multilayer Organic Substrates, package, water. I. INTRODUCTION MICROWAVE and millimeter-wave (mm-wave) radio-fre- quency (RF) circuits Member, IEEE Abstract--The feasibility of using near-hermetic organic mate- rials for microwave

Tentzeris, Manos

354

Preconcentration of Heavy Metal Lead in Environmental Water Sample with Chicken Eggshell Membrane Cartridge Prior to Atomic Absorption Spectrometry  

Microsoft Academic Search

In order to evaluate the effects of heavy metals discharged in the environment water, a novel method using a glass column packed with chicken eggshell membrane (ESM) as a new adsorption material was developed for the preconcentration of trace Pb in environmental water sample prior to its determination by atomic absorption spectrometry (AAS). The adsorption behaviors of the analytes on

Hong-mei Chen; Jin Liu; Li-sha Zhang; Yuan Peng; Bin Ren

2011-01-01

355

Metabolic changes associated with active water vapour absorption in the mealworm Tenebrio molitor L. (Coleoptera, Tenebrionidae): A microcalorimetric study  

Microsoft Academic Search

Water vapour absorption (WVA) is an important mechanism for water gain in several xeric insects. Theoretical calculations indicate that the energetic cost of WVA should be small (5–10% of standard metabolic rate) assuming realistic efficiencies. In this study we explored the relationship between WVA, metabolic heat flux (HFmet.) and CO2 release in larvae of Tenebrio molitor using microcalorimetry. By comparing

Lars L. Hansen; Peter Westh; Jonathan C. Wright; Hans Ramløv

2006-01-01

356

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

357

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

PubMed

The scanning ion-selective electrode technique (SIET) was utilized for the first time in Locusta migratoria to characterize K(+) transport along the digestive tract and to determine the effect of two locust FGLamide allatostatins (FGLa/ASTs) on K(+) transport: a previously sequenced FGLa/AST from Schistocerca gregaria (Scg-AST-6; ARPYSFGL-NH2) and a newly sequenced FGLa/AST from L. migratoria (Locmi-FGLa/AST-2; LPVYNFGL-NH2). Regional differences in K(+) fluxes along the gut were evident, where K(+) efflux in vitro (or absorption into the hemolymph in vivo) was greatest at the anterior ileum, and lowest at the colon. Ileal K(+) efflux was inhibited by both Scg-AST-6 and Locmi-FGLa/AST-2, with maximal inhibition at 10(-10) and 10(-11) mol l(-1), respectively. Both FGLa/ASTs also inhibited cAMP-stimulated K(+) efflux from the ileum. Locmi-FGLa/AST-2 also inhibited efflux of water across the ileum. Locusts are terrestrial insects living in dry climates, risking desiccation and making water conservation a necessity. The results suggest that FGLa/ASTs may be acting as diuretics by increasing K(+) excretion and therefore increasing water excretion. Thus it is likely that FGLa/ASTs are involved in the control of hemolymph water and ion levels during feeding and digestion, to help the locust deal with the excess K(+) load (and subsequently fluid) when the meal is processed. PMID:25013112

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

2014-09-15

358

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

359

Chromatographic determination of octanol-water partition coefficients (K/sub ow/'s) for 58 polychlorinated biphenyl congeners  

SciTech Connect

Octanol-water partition coefficients of 58 poly-chlorinated biphenyl (PCB) congeners have been determined by reverse-phase C/sub 18/ high-performance liquid chromatography (HPLC) of Aroclor 1242 and 1254 mixtures. High-resolution glass capillary gas-liquid chromatography was used for the detection of the eluted individual congeners. Some PCB congeners behaved atypically from other organics on reverse-phase HPLC, and empirically derived correction factors were used to adjust K/sub ow/ values. Congener log K/sub ow/ values for PCB's ranged from an average of 4.5 for N/sub Cl/ = 1 to 8.1 for N/sub Cl/ = 7. The environmental implications of PCB K/sub ow/ values and congener behavior on the C /sub 18/ reverse-phase column are discussed. 35 references.

Rapaport, R.A.; Eisenreich, S.J.

1984-03-01

360

Pressure dependence of diffusion coefficient and orientational relaxation time for acetonitrile and methanol in water: DRISM/mode-coupling study  

E-print Network

We present results of theoretical description and numerical calculation of the dynamics of molecular liquids based on the Reference Interaction Site Model / Mode-Coupling Theory. They include the temperature-pressure(density) dependence of the translational diffusion coefficients and orientational relaxation times for acetonitrile and methanol in water at infinite dilution. Anomalous behavior, i.e. the increase in mobility with density, is observed for the orientational relaxation time of methanol, while acetonitrile does not show any deviations from the usual. This effect is in qualitative agreement with the recent data of MD simulation and with experimental measurements, which tells us that presented theory is a good candidate to explain such kind of anomalies from the microscopical point of view and with the connection to the structure of the molecules.

Kobryn, A E; Hirata, F

2005-01-01

361

Infrared- and millimeter-wavelength absorption in the atmospheric windows by water vapor and nitrogen - Measurements and models  

NASA Astrophysics Data System (ADS)

The current knowledge of the water vapor window regions from 10 to 1000 GHz, 8 to 12 microns, 3 to 5 microns, and 2 to 2.5 microns is reviewed with emphasis on the continuum absorption observed in each window region. The observed frequency dependence in each window is consistent with the concept of far wings emanating from the bordering water vapor absorption bands, which provides a promising basis for modeling continuum absorption. Theoretical line-shape models predict the observed frequency and pressure dependence of absorption but thus far not the temperature dependence. A model for the integrated intensity of the nitrogen continuum is developed as a function of density and temperature.

Thomas, Michael E.

1988-01-01

362

Temperature dependencies of Henry's law constants and octanol/water partition coefficients for key plant volatile monoterpenoids.  

PubMed

To model the emission dynamics and changes in fractional composition of monoterpenoids from plant leaves, temperature dependencies of equilibrium coefficients must be known. Henry's law constants (H(pc), Pa m3 mol(-1) and octanol/water partition coefficients (K(OW), mol mol(-1)) were determined for 10 important plant monoterpenes at physiological temperature ranges (25-50 degrees C for H(pc) and 20-50 degrees C for K(OW)). A standard EPICS procedure was established to determine H(pc) and a shake flask method was used for the measurements of K(OW). The enthalpy of volatilization (deltaH(vol)) varied from 18.0 to 44.3 kJ mol(-1) among the monoterpenes, corresponding to a range of temperature-dependent increase in H(pc) between 1.3- and 1.8-fold per 10 degrees C rise in temperature. The enthalpy of water-octanol phase change varied from -11.0 to -23.8 kJ mol(-1), corresponding to a decrease of K(OW) between 1.15- and 1.32-fold per 10 degrees C increase in temperature. Correlations among physico-chemical characteristics of a wide range of monoterpenes were analyzed to seek the ways of derivation of H(pc) and K(OW) values from other monoterpene physico-chemical characteristics. H(pc) was strongly correlated with monoterpene saturated vapor pressure (P(v)), and for lipophilic monoterpenes, deltaH(vol) scaled positively with the enthalpy of vaporization that characterizes the temperature dependence of P(v) Thus, P(v) versus temperature relations may be employed to derive the temperature relations of H(pc) for these monoterpenes. These data collectively indicate that monoterpene differences in H(pc) and K(OW) temperature relations can importantly modify monoterpene emissions from and deposition on plant leaves. PMID:15967478

Copolovici, Lucian O; Niinemets, Ulo

2005-12-01

363

Effect of line, soaking and cooking time on water absorption, texture and splitting of red kidney beans.  

PubMed

Dry beans are rich sources of dietary fiber and phytochemicals such as flavonoids and phenolics that exhibit good functional properties. In current study line, cooking and soaking time effects were investigated on water absorption, splitting and texture of different Iranian red kidney beans to determine the best lines and the best soaking time related to them for industrial use. D81083 line had the highest level of water absorption after 24 h soaking followed by Akhtar and KS31164 lines while Azna, Goli and Naz lines had the lowest level of water absorption (p?water absorption accompanied with low splitting level. 24 h soaking and longer cooking time is recommended for Sayyad, while 12 h soaking and longer cooking time is recommended for KS31164 line. 24 h soaking causes higher level of water absorption and lower level of splitting in Derakhshan line. The effects of line, cooking and soaking time on red bean texture were significant (p?

Zamindar, Nafiseh; Baghekhandan, Mohamad Shahedi; Nasirpour, Ali; Sheikhzeinoddin, Mahmoud

2013-02-01

364

Sexually dimorphic basal water absorption at the isolated pelvic patch of Japanese tree frog, Hyla japonica.  

PubMed

Frogs ingest little water orally, but absorb the majority of the water needed for normal physiological performance through a specific region of the ventral skin, the pelvic patch. We observed non-stimulated (basal water absorption, BWA) water flux through the isolated pelvic patch in vitro in Japanese tree frog (Hyla japonica). We found that water flux through non-stimulated skin from the pelvic patch was greater in males than females. This water flux was confirmed as BWA by observing no effect following the in vitro administration of propranolol and [adamantaneacetyl(1), O-Et-D-Tyr(2), Val(1), aminobutyryl(6), Arg(8, 9)] vasopressin, which are a beta-adrenergic receptor antagonist and a vasopressin V2 receptor antagonist, respectively. We further examined this phenomenon following gonadectomy, treatment with sex hormones (E2, 17beta-estradiol; TP, testosterone propionate), estrogenic chemicals (BPA, bisphenol A; MTX, methoxychlor) or prolactin (PRL, a hormone regulated by sex hormones that has osmoregulatory activity). Ovariectomy increased BWA in females. Injection (in vivo treatment) of E2 or PRL reduced BWA in males, whereas TP injection increased BWA in females. However, the in vitro addition of E2, TP, or PRL to the Ringer's solution on the serosal side of the ventral skin patch did not alter BWA. Subsequently, we injected (in vivo treatment) BPA or MTX, environmental chemical contaminants with known hormonal actions in mammals. Injection of BPA or MTX reduced BWA in males as observed following treatment with E2. These results provide the first evidence of sexual dimorphism in BWA through the isolated pelvic patch. The gonad appears essential for observed sexual dimorphism in BWA, and we hypothesize that sex hormones regulate the release of PRL, that in turn influences BWA indirectly. E2 is known to exert a specific stimulatory effect on PRL secretion. In addition, we have observed that some endocrine disrupting contaminants also eliminate the sexual dimorphism in BWA observed in the Japanese tree frog. PMID:15114650

Kohno, Satomi; Fujime, Makoto; Kamishima, Yoshihisa; Iguchi, Taisen

2004-05-01

365

Water absorption characteristics of novel Cu/LDPE nanocomposite for use in intrauterine devices.  

PubMed

Intrauterine devices (IUDs), especially the copper-containing IUDs (Cu-IUDs), are one of the worldwide used forms for birth control, owing to their advantages of long-lasting and high efficacy, economy, safety, and reversibility. However, it is not perfect for the existing Cu-IUDs; some shortcomings related to its side effects have not been overcome yet. For this reason, a new Cu-IUDs material, the copper/low-density polyethylene (Cu/LDPE) nanocomposite, has been developed in our research team. The structure and water uptake characteristics of this new Cu-IUDs material have been investigated by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and gravimetric analysis in this paper. The results of XRD, SEM, EDS, and FT-IR show three important outcomes associated with the structure of the nanocomposite. First, the nanocomposite is hybrid of the polymer and the copper nanoparticles (nano-Cu). Second, porosities, nano-Cu aggregates, and primary alcohol (R--CH(2)--OH) are existed in the nanocomposite. Third, the nano-Cu aggregates are distributed uniformly in the polymer matrix in general. The results of Gravimetric analysis, which associated with the water uptake characteristics of the nanocomposite, exhibit that the water absorption behavior of the nanocomposite obeys the classical diffusion theory very well, the water uptake of the nanocomposite increases with the increasing of the nano-Cu loading, and that the water uptake ability of the nanocomposite with 15.0 wt % nano-Cu (50 nm in diameter) is about 150 times larger than that of the base resin and about 45 times higher than that of the Cu/LDPE microcomposite with 15.0 wt % copper microparticles (5 microm in diameter). These water uptake characteristics are mainly attributed to the structure of the Cu/LDPE composites and the size effect of the nano-Cu. PMID:16637033

Xia, Xianping; Cai, Shuizhou; Hu, Junhui; Xie, Changsheng

2006-11-01

366

An alternative approach for the use of water solubility of nonionic pesticides in the modeling of the soil sorption coefficients.  

PubMed

The collection of data to study the damage caused by pesticides to the environment and its ecosystems is slowly acquired and costly. Large incentives have been established to encourage research projects aimed at building mathematical models for predicting physical, chemical or biological properties of environmental interest. The organic carbon normalized soil sorption coefficient (K(oc)) is an important physicochemical property used in environmental risk assessments for compounds released into the environment. Many models for predicting logK(oc) that have used the parameters logP or logS as descriptors have been published in recent decades. The strong correlation between these properties (logP and logS) prevents them from being used together in multiple linear regressions. Because the sorption of a chemical compound in soil depends on both its water solubility and its water/organic matter partitioning, we assume that models capable of combining these two properties can generate more realistic results. Therefore, the objective of this study was to propose an alternative approach for modeling logK(oc), using a simple descriptor of solubility, here designated as the logarithm of solubility corrected by octanol/water partitioning (logS(P)). Thus, different models were built with this descriptor and with the conventional descriptors logP and logS, alone or associated with other explanatory variables representing easy-to-interpret physicochemical properties. The obtained models were validated according to current recommendations in the literature, and they were compared with other previously published models. The results showed that the use of logS(p) instead of conventional descriptors led to simple models with greater statistical quality and predictive power than other more complex models found in the literature. Therefore, logS(P) can be a good alternative to consider for the modeling of logK(oc) and other properties that relate to both solubility and water/organic matter partitioning. PMID:24525068

dos Reis, Ralpho Rinaldo; Sampaio, Silvio César; de Melo, Eduardo Borges

2014-04-15

367

Gut-brain signaling of water absorption inhibits vasopressin in rats.  

PubMed

The mechanism for inhibition of vasopressin (AVP) by gastric water infusion was examined in 24- or 48-h dehydrated conscious rats (n = 136 rats, 255 experiments; mean AVP baseline = 6.3 pg/ml). Gastric water infusions of 1 (n = 8), 2.5 (n = 19), and 4 ml (n = 10) caused a volume-dependent inhibition of plasma AVP by -0.31, -1.77*, and -3.02* pg/ml, with decreases of systemic osmolality of -1.06, -1.52, and -4.26* mosmol/kgH2O (* = significant vs. isotonic, Duncan's test). Gastric isotonic infusions (1-4 ml) had no effect or slightly increased AVP. Systemic infusions of 1.25 (n = 6), 2.1 (n = 10), and 6.3 ml (n = 8) inhibited AVP by -0.48, -1.07, and -2.51 pg/ml, with decreases in systemic osmolality of -1.61, -2.77*, and -7.21* mosmol/kgH2O. Systemic isotonic infusions (2.1 and 6.3 ml) slightly inhibited AVP by -0.71 and -0.85 pg/ml. Individual changes in AVP by gastric infusion of 2.5 ml of water did not correlate with changes in systemic osmolality, mean arterial pressure, or heart rate but highly correlated with preinfusion AVP (r = 0.74, P < 0.0001, n = 28). Pretreatment with systemic atropine methyl bromate (0.7 mg/rat), which abolishes the AVP secretion to gastric hypertonic saline, did not affect the AVP response to gastric water infusion (n = 9). Combination of 2.5 ml of gastric water and systemic hypertonic saline prevented the decrease in systemic osmolality and still significantly inhibited plasma AVP. Maximal inhibition of AVP by gastric water was reduced by 62.6% after lesion of the common hepatic vagal branch (n = 5) relative to shams with identical abdominal surgery (n = 6) and by 62.7 and 72.5% after right (n = 11) and left (n = 8) cervical vagotomy relative to 12 shams (P < 0.05). The results show that 1) gastric water absorption is signaled mainly by splanchnic osmosensors, 2) water signaling is atropine insensitive, and 3) the major water-signaling pathway projects through the common hepatic vagal branch and cervical vagal nerves. PMID:7840327

Baertschi, A J; Pence, R A

1995-01-01

368

Removal of Heavy Metals from Water: An Environmentally Significant Atomic Absorption Spectrometry Experiment  

NASA Astrophysics Data System (ADS)

A laboratory experiment that combines the environmentally significant topic of wastewater treatment with atomic absorption spectrometry (AAS) is described. In the first portion of the laboratory project, students perform treatment studies on simulated wastewater samples that contain heavy metal contaminants common to the effluent of the metal finishing industry. Following pretreatment reduction of Cr(VI) to Cr(III), sparingly soluble metal hydroxides are produced by pH adjustment and removed by filtration with the aid of a polyacrylamide flocculant. In the second portion of the experiment, AAS is used to determine metal concentrations in treated and untreated water samples, thus enabling the students to determine the effectiveness of the treatment process. Details of how this experiment integrates topics such as the pH-dependent solubility of metal hydroxides, complex equilibria, matrix interference, and polymers in the context of an environmentally important analysis are presented.

Buffin, Brian P.

1999-12-01

369

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

NASA Technical Reports Server (NTRS)

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

Kenimer, R. L.

1988-01-01

370

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

SciTech Connect

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

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

1996-05-14

371

A Water Vapor Differential Absorption LIDAR Design for Unpiloted Aerial Vehicles  

NASA Technical Reports Server (NTRS)

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

DeYoung, Russell J.; Mead, Patricia F.

2004-01-01

372

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

SciTech Connect

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

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

2008-02-16

373

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

PubMed

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

Bösenberg, J

1998-06-20

374

Measurements of water vapour in the mesosphere with the spectral absorption line imager (SALI)  

NASA Astrophysics Data System (ADS)

Water vapour concentration is one of the most important, yet one of the least known quantities of the mesosphere. Knowledge of water vapour concentration is the key to understanding many mesospheric processes, including the one that is primary focus of our investigation, Polar Mesospheric Clouds (PMC). The processes of formation and occurrence parameters of PMC constitute an interesting problem in their own right, but recent evidence had been provided which suggests that PMC are a critical indicator of climate change. In this context the feasibility of a low cost method of water vapour measurements using an instrument carried aloft by a sounding rocket has been examined and some of the results discussed. It is proposed to measure the strength of the 936nm water absorption line in a solar occultation configuration employing a CCD detector. This leads to the design of a small, low cost and low-mass instrument, which can be flown on a small rocket, of the type of the Orbital Sciences Corporation Viper 5. Alternatively the instrument can be flown as a "passenger" on larger rocket carrying other experiments. In either case flight costs are relatively low. Some performance simulations are presented showing that the instrument we have designed will be sufficiently sensitive to measure water vapor in concentrations that are expected at the summer mesopause, about 85 km height. Sufficient payload design work was carried out showing that the structural, thermal and electrical requirements for a flight on the Viper 5 rocket can be met and thus making the experiment feasible for a flight.

Shepherd, M. G.; Sargoytchev, S. I.; Brown, S.; Mullins, M.; Petersen, J.

375

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

PubMed

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

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

2012-08-01

376

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

SciTech Connect

We study the variability of major atmospheric absorption features in the disk-integrated spectra of Earth with future application to Earth-analogs in mind, concentrating on the diurnal timescale. We first analyze observations of Earth provided by the EPOXI mission, and find 5%-20% fractional variation of the absorption depths of H{sub 2}O and O{sub 2} bands, two molecules that have major signatures in the observed range. From a correlation analysis with the cloud map data from the Earth Observing Satellite (EOS), we find that their variation pattern is primarily due to the uneven cloud cover distribution. In order to account for the observed variation quantitatively, we consider a simple opaque cloud model, which assumes that the clouds totally block the spectral influence of the atmosphere below the cloud layer, equivalent to assuming that the incident light is completely scattered at the cloud top level. The model is reasonably successful, and reproduces the EPOXI data from the pixel-level EOS cloud/water vapor data. A difference in the diurnal variability patterns of H{sub 2}O and O{sub 2} bands is ascribed to the differing vertical and horizontal distribution of those molecular species in the atmosphere. On Earth, the inhomogeneous distribution of atmospheric water vapor is due to the existence of its exchange with liquid and solid phases of H{sub 2}O on the planet's surface on a timescale short compared with atmospheric mixing times. If such differences in variability patterns were detected in spectra of Earth-analogs, it would provide the information on the inhomogeneous composition of their atmospheres.

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

2013-03-10

377

Water absorption in the proximal tubule: effect of bicarbonate, chloride gradient, and organic solutes.  

PubMed

Simultaneous in vivo capillary and luminal microperfusion studies were performed in the superficial proximal convoluted tubule of the rat to determine the effect of intraluminal bicarbonate, the imposition of a transepithelial chloride gradient, and the addition of organic solutes to the luminal perfusion solution on the rates of water absorption (Jv). The capillary perfusion solution contained NaCl, NaHCO3, and KCl. Perfusion of both capillary and lumen with the same solution resulted in a Jv of 3.01 +/- 0.24 nl/min/mm. Imposition of a transepithelial chloride gradient (equimolar substitution of NaCl for NaHCO3 in the luminal solution) resulted in a Jv of 3.18 +/- 0.21 nl/min/mm (P = NS). Addition of cyanide to both solutions in the presence of a chloride gradient resulted in a significantly lower Jv of 2.21 +/- 0.19 nl/min/mm. Luminal substitution of Na cyclamate for NaHCO3 resulted in a solution containing no bicarbonate and no chloride gradient. Jv averaged 0.34 +/- 0.08 nl/min/mm. Addition of cyanide to the solution totally inhibited Jv. The addition of D-glucose, L-alanine, or both, to luminal solutions containing bicarbonate or in the presence of a chloride gradient did not significantly affect Jv. Addition of both organic solutes to the NaCl-Na cyclamate luminal solution resulted in a significantly higher Jv of 0.77 +/- 0.14 nl/min/mm. These studies indicate that Jv in the rat superficial proximal tubule is influenced by active sodium transport, by the presence of bicarbonate in the lumen, and/or by the imposition of a transepithelial chloride gradient. The organic solutes D-glucose and L-alanine also influence water absorption, but this effect could only be demonstrated under some experimental conditions. PMID:6828448

Sansom, S C; Senekjian, H O; Knight, T F; Frommer, P; Weinman, E J

1983-01-01

378

Ground-state ammonia and water in absorption towards Sgr B2  

NASA Astrophysics Data System (ADS)

Context. Observations of transitions to the ground-state of a molecule are essential to obtain a complete picture of its excitation and chemistry in the interstellar medium, especially in diffuse and/or cold environments. For the important interstellar molecules H2O and NH3, these ground-state transitions are heavily absorbed by the terrestrial atmosphere, hence not observable from the ground. Aims: We attempt to understand the chemistry of nitrogen, oxygen, and their important molecular forms, NH3 and H2O in the interstellar medium of the Galaxy. Methods: We have used the Odin* submillimetre-wave satellite telescope to observe the ground state transitions of ortho-ammonia and ortho-water, including their 15N, 18O, and 17O isotopologues, towards Sgr B2. The extensive simultaneous velocity coverage of the observations, >500 km s-1, ensures that we can probe the conditions of both the warm, dense gas of the molecular cloud Sgr B2 near the Galactic centre, and the more diffuse gas in the Galactic disk clouds along the line-of-sight. Results: We present ground-state NH3 absorption in seven distinct velocity features along the line-of-sight towards Sgr B2. We find a nearly linear correlation between the column densities of NH3 and CS, and a square-root relation to N2H+. The ammonia abundance in these diffuse Galactic disk clouds is estimated to be about 0.5-1 × 10-8, similar to that observed for diffuse clouds in the outer Galaxy. On the basis of the detection of H_218O absorption in the 3 kpc arm, and the absence of such a feature in the H_217O spectrum, we conclude that the water abundance is around 10-7, compared to ~10-8 for NH3. The Sgr B2 molecular cloud itself is seen in absorption in NH3, 15NH3, H2O, H_218O, and H_217O, with emission superimposed on the absorption in the main isotopologues. The non-LTE excitation of NH3 in the environment of Sgr B2 can be explained without invoking an unusually hot (500 K) molecular layer. A hot layer is similarly not required to explain the line profiles of the 11,0?ts10,1 transition from H2O and its isotopologues. The relatively weak 15NH3 absorption in the Sgr B2 molecular cloud indicates a high [ 14N/15N] isotopic ratio >600. The abundance ratio of H_218O and H_217O is found to be relatively low, 2.5-3. These results together indicate that the dominant nucleosynthesis process in the Galactic centre is CNO hydrogen burning. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and the centre National d'Études Spatiales (CNES, France). The Swedish Space Corporation (SSC) was the industrial prime contractor and is also responsible for the satellite operation.

Wirström, E. S.; Bergman, P.; Black, J. H.; Hjalmarson, Å.; Larsson, B.; Olofsson, A. O. H.; Encrenaz, P. J.; Falgarone, E.; Frisk, U.; Olberg, M.; Sandqvist, Aa.

2010-11-01

379

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

USGS Publications Warehouse

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

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

2013-01-01

380

[Determination of lithium in the oil field water by flame atomic absorption spectrometry].  

PubMed

Flame atomic absorption spectrometry was applied to the determination of micro amount of lithium in the oil field water of certain area. In order to determine which method is more appropriate for the determination of lithium content in the oil field water, standard curve method and standard addition method were compared. The effects of dilution, coexistent ions, and deionizers on the determination were studied. For the determination of lithium content in the same diluted oil field water samples, there exist obvious differences between the results obtained from standard addition method and standard curve method. Standard addition method gives results with a larger error, whereas standard curve method gives more accurate results. It is difficult to eliminate the interferences when the standard addition method is used. The standard curve method is found to be more suitable for the determination of micro amount of lithium in the oil field water for its accuracy, simplicity, and feasibility. When the standard curve method is used, both the determined lithium concentration and the recovery change with the dilution extent of the oil field water. In order to get an accurate result, the oil field water sample should be diluted to 1/200 or less. In this case, the recovery by standard addition method ranges from 94.3% to 96.9%. When sodium phosphate or sodium chloride is used as the deionizer, the recovery by standard addition method ranges from 94.6% to 98.6%, or from 94.2% to 96.3%. In the determination of lithium content in oil field water, there are larger experimental errors without the addition of any deionizer. When the concentration of coexistent ions is within an allowed range, the addition of sodium phosphate as a deionizer can eliminate the interferences of the coexistent ions with the determination of the lithium content. If sodium chloride is used as a deionizer, a more accurate result can be obtained when the sodium content in the samples is near the sodium content in the standard solutions. In general, under suitable experimental conditions, sodium chloride can be used as the deionizer for the determination of lithium content in the oil field water. PMID:19385254

Yang, Hong-Jun; Ye, Xiu-Shen; Li, Bing; Wu, Zhi-Jian; Li, Wu

2009-01-01

381

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

NASA Astrophysics Data System (ADS)

Carbonyl sulfide and carbon monoxide are both atmospheric trace gases of high interest. Recent advances in the field of spectroscopy have enabled instruments that measure the concentration of the above and other trace gases very fast and with good precision. Increasing the effective path length by reflecting the light between two mirrors in a cavity, these instruments reach impressive sensitivities. Often it is possible to measure the concentration of more than one trace gas at the same time. The OCS/CO2 Analyzer by LGR (Los Gatos Research, Inc.) measures the concentration of water vapor [H2O], carbonyl sulfide [COS], carbon dioxide [CO2] and carbon monoxide [CO] simultaneously. For that the cavity is saturated with light, than the attenuation of light is measured as in standard absorption spectroscopy. The instrument proved to be very fast with good precision and to be able to detect even very low concentrations, especially for COS (as low as 30ppt in the case of COS). However, we observed a rather strong cross sensitivity to water vapor. Altering the water vapor content of the sampled air with two different methods led to a change in the perceived concentration of COS, CO and CO2. This proved especially problematic for enclosure (cuvette) measurements, where the concentrations of one of the above species in an empty cuvette are compared to the concentration of another cuvette containing a plant whose exchange of trace gases with the atmosphere is of interest. There, the plants transpiration leads to a large difference in water vapor content between the cuvettes and that in turn produces artifacts in the concentration differences between the cuvettes for the other above mentioned trace gases. For CO, simultaneous measurement with a UV-Emission Analyzer (AL 5002, Aerolaser) and the COS/CO Analyzer showed good agreement of perceived concentrations as long as the sample gas was dry and an increasing difference in perceived concentration when the sample gas was humidified. The difference in perceived CO concentration showed a clear correlation to the water vapor content in the sample air. For COS we could show that changes in water vapor also impacted on the perceived COS concentrations; the raise of the water vapor concentration would lead to an increasing underestimation of the COS concentration. Drying the air using a Nafion Dryer before entering the COS/CO Analyzer eliminated any water vapor induced artifacts and showed no adverse effects on the quality of the conducted measurements. *Integrated cavity output spectroscopy

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

2014-05-01

382

Development of a standard for calculation and measurement of the moderator temperature coefficient of reactivity in water-moderated power reactors  

SciTech Connect

The contents of ANS 19.11, the standard for ``Calculation and Measurement of the Moderator Temperature Coefficient of Reactivity in Water-Moderated Power Reactors,`` are described. The standard addresses the calculation of the moderator temperature coefficient (MTC) both at standby conditions and at power. In addition, it describes several methods for the measurement of the at-power MTC and assesses their relative advantages and disadvantages. Finally, it specifies a minimum set of documentation requirements for compliance with the standard.

Mosteller, R.D. [Los Alamos National Lab., NM (United States); Hall, R.A. [Virginia Power, Glen Allen, VA (United States). Innsbrook Technical Center; Apperson, C.E. Jr. [Westinghouse Safety Management Solutions, Inc., Aiken, SC (United States); Lancaster, D.B. [TRW Environmental Safety Systems, Inc., Vienna, VA (United States); Young, E.H. [Commonwealth Edison Co., Downers Grove, IL (United States); Gavin, P.H. [ABB Combustion Engineering, Windsor, CT (United States); Robertson, S.T. [Framatome/COGEMA Fuels, Lynchburg, VA (United States)

1998-12-01

383

Improved water and sodium absorption from oral rehydration solutions based on rice syrup in a rat model of osmotic diarrhea.  

PubMed

Rice syrup solids, rice protein, and casein hydrolysate were added to experimental oral rehydration solutions in various combinations and tested in a rat intestinal perfusion system. Chronic osmotic diarrhea was induced in juvenile rats by supplying the cathartic agents, magnesium citrate and phenolphthalein, in their drinking water for 1 week. The experimental oral rehydration solutions were compared with standard oral rehydration solutions containing 20 gm/L or 30 gm/L of glucose and with each other to determine if there were significant differences in net water, sodium, or potassium absorption. An oral rehydration solution containing 30 gm/L of rice syrup solids had a net water absorption rate significantly higher than that of the standard 20 gm/L glucose-based oral rehydration solution (2.1 +/- 0.62 versus 1.5 +/- 0.48 microliters/[min x cm], p less than 0.05). Casein hydrolysate did not significantly affect net water absorption. However, combinations of 30 gm/L rice syrup solids and 5 gm/L casein hydrolysate significantly increased (p less than 0.05) net sodium and potassium absorption compared with the 20 gm/L glucose-based oral rehydration solution but not versus rice syrup solids alone. Oral rehydration solutions containing 30 gm/L rice syrup solids plus 5 gm/L rice protein, and 30 gm/L rice syrup solids plus 5 gm/L casein hydrolysate, had net water absorption rates significantly higher than the rate of a 30 gm/L glucose-based oral rehydration solution (2.5 +/- 0.36 and 2.4 +/- 0.38, respectively, versus 0.87 +/- 0.40 microliters/[min x cm], p less than 0.05). Rice protein and casein hydrolysate, however, did not significantly affect net water, sodium, or potassium absorption when added to rice protein glucose-based oral rehydration solutions. An inverse correlation between osmolality and net water absorption was observed (r = -0.653, p less than 0.02). The data suggest that substitution of rice syrup solids for glucose in oral rehydration solutions will improve water absorption and that rice syrup solids in combination with protein hydrolysates may, in addition, promote better sodium and potassium uptake. PMID:2007957

Wapnir, R A; Litov, R E; Zdanowicz, M M; Lifshitz, F

1991-04-01

384

The room temperature annealing peak in ionomers: Ionic crystallites or water absorption  

SciTech Connect

A quaternized diol, 3-(trimethylammonio)-1,2-propanediol neutralized with either bromine or iodine, was used to produce a polyurethane cationomer with a poly(tetramethylene oxide) soft segment and a 4,4[prime]-diphenylmethane diisocyanate hard segment. If those cationomers were annealed at room temperature for a period of approximately 1 month in a desiccator filled with dry CaSO[sub 4], differential scanning calorimetry (DSC) studies showed an endotherm centered near 70 C which was not present in the unannealed polymer and did not reappear upon subsequent cooling and heating cycles in the DSC. Some authors have suggested that a very similar endotherm found in other ionomers, most notably ethylene-methacrylic acid (E-MAA) copolymer ionomers, was due to an order-disorder transition within the ionic aggregates, i.e. ionic crystallite melting. In order to isolate the origin of this endotherm, the local environment around the anion in compression molded bromine neutralized samples was measured using the extended X-ray absorption fine-structure (EXAFS) technique. By measuring the change in the local environment over the temperature range corresponding to the DSC endotherm, it has been shown that this endotherm corresponds to water leaving the bromine coordination shell, rather than ionic crystallite melting. Other studies which include thoroughly drying the material in a vacuum oven below the transition temperature to remove the water suggest that the endotherm is due to the energetic change associated with water leaving the coordination environment of the anion in combination with water vaporization.

Goddard, R.J.; Grady, B.P.; Cooper, S.L. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemical Engineering)

1994-03-28

385

Atmospheric-water absorption features near 2.2 micrometers and their importance in high spectral resolution remote sensing  

NASA Technical Reports Server (NTRS)

Selective absorption of electromagnetic radiation by atmospheric gases and water vapor is an accepted fact in terrestrial remote sensing. Until recently, only a general knowledge of atmospheric effects was required for analysis of remote sensing data; however, with the advent of high spectral resolution imaging devices, detailed knowledge of atmospheric absorption bands has become increasingly important for accurate analysis. Detailed study of high spectral resolution aircraft data at the U.S. Geological Survey has disclosed narrow absorption features centered at approximately 2.17 and 2.20 micrometers not caused by surface mineralogy. Published atmospheric transmission spectra and atmospheric spectra derived using the LOWTRAN-5 computer model indicate that these absorption features are probably water vapor. Spectral modeling indicates that the effects of atmospheric absorption in this region are most pronounced in spectrally flat materials with only weak absorption bands. Without correction and detailed knowledge of the atmospheric effects, accurate mapping of surface mineralogy (particularly at low mineral concentrations) is not possible.

Kruse, F. A.; Clark, R. N.

1986-01-01

386

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

NASA Astrophysics Data System (ADS)

Enhancement of the gamma radiation grafting of acrylonitrile onto gelatinized cassava starch was investigated. Infrared spectrometry was used to follow the chemical changes in the grafting reaction and from saponification. The saponified starch- g-PAN (HSPAN) was then characterized in terms of grafting parameters to provide a guide for the optimum total dose (kGy) and the appropriate ratio of starch/acrylonitrile for a fixed dose rate of 2.5 × 10 -1 kGy/min. Other dose rates were also carried out to obtain the appropriate result of grafting copolymerization and of water absorption. A thin aluminium foil, covering the inner wall of the reaction vessel, was found to be far more effective than any other metal films in the enhancement of the grafting reaction and the water absorption as well. Nitric acid in the medium increases the grafting yield and the water absorption. Methyl ether hydroquinone inhibitor was evaluated for its ability to increase homopolymerization and decrease graft reaction. When styrene was used as a comonomer, it hampered the grafting of acrylonitrile onto starch backbone. The water absorption capacity was improved by freeze-drying the HSPAN. The treatment of the HSPAN with aluminium trichloride hexahydrate was found to enhance the degree of wicking, but to decrease the water absorbency.

Kiatkamjornwong, Suda; Meechai, Nispa

1997-06-01

387

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

388

Adsorption of HCl on the water ice surface studied by X-ray absorption spectroscopy.  

PubMed

The adsorption state of HCl at 20 and 90 K on crystalline water ice films deposited under ultrahigh vacuum at 150 K has been studied by X-ray absorption spectroscopy at the O1s K-edge and Cl2p L-edge. We show that HCl dissociates at temperatures as low as 20 K, in agreement with the prediction of a spontaneous ionization of HCl on ice. Comparison between the rate of saturation of the "dangling" hydrogen bonds and the chlorine uptake indicates that hydrogen bonding of HCl with the surface native water "dangling" groups only accounts for a small part of the ionization events (20% at 90 K). A further mechanism drives the rest of the dissociation/solvation process. We suggest that the weakening of the ice surface hydrogen-bond network after the initial HCl adsorption phase facilitates the generation of new dissociation/solvation sites, which increases the uptake capacity of ice. These results also emphasize the necessity to take into account not only a single dissociation event but its catalyzing effect on the subsequent events when modeling the uptake of hydrogen-bonding molecules on the ice surface. PMID:16851126

Parent, Ph; Laffon, C

2005-02-01

389

Light tracking through ice and water -- Scattering and absorption in heterogeneous media with Photonics  

E-print Network

In the field of neutrino astronomy, large volumes of optically transparent matter like glacial ice, lake water, or deep ocean water are used as detector media. Elementary particle interactions are studied using in situ detectors recording time distributions and fluxes of the faint photon fields of Cherenkov radiation generated by ultra-relativistic charged particles, typically muons or electrons. The Photonics software package was developed to determine photon flux and time distributions throughout a volume containing a light source through Monte Carlo simulation. Photons are propagated and time distributions are recorded throughout a cellular grid constituting the simulation volume, and Mie scattering and absorption are realised using wavelength and position dependent parameterisations. The photon tracking results are stored in binary tables for transparent access through ANSI-C and C++ interfaces. For higher-level physics applications, like simulation or reconstruction of particle events, it is then possible to quickly acquire the light yield and time distributions for a pre-specified set of light source and detector properties and geometries without real-time photon propagation. In this paper the Photonics light propagation routines and methodology are presented and applied to the IceCube and Antares neutrino telescopes. The way in which inhomogeneities of the Antarctic glacial ice distort the signatures of elementary particle interactions, and how Photonics can be used to account for these effects, is described.

J. Lundberg; P. Miocinovic; K. Woschnagg; T. Burgess; J. Adams; S. Hundertmark; P. Desiati; P. Niessen

2007-02-05

390

Terahertz Absorption of Chemicals in Water: Ideal and Real Solutions and Mixtures  

NASA Astrophysics Data System (ADS)

Complex biomolecules, such as proteins in liquids, show specific terahertz dynamics in reactions or in protein folding as measured by static or kinetic absorption. The complex nature of biomolecules requires investigating their frequency, space, and time characteristics via a multimodal approach that changes external parameters such as temperature, pressure, concentration, and solvents. Terahertz spectroscopy can add a new and deeper understanding to existing techniques in other spectral regions of the biological dynamics in the solvent of life, i.e. water. To understand more deeply complex liquids or macromolecules in water, it is essential to understand the building blocks of solutions, which may contain salts, or are components of larger molecules such as amino acids. Although this research mainly affects basic science, a few applications are in progress, some create interest in industry, and several pathways for new applications relevant to medical science are in view. In this article, we review THz spectroscopy of solutions and concentrate our description to liquids with small solutes such as salts and amino acids, and review the prerequisites for obtaining THz data from aqueous solutions.

Funkner, Stefan; Niehues, Gudrun; Schmidt, Diedrich A.; Bründermann, Erik

2013-08-01

391

In Situ Intestinal Absorption of a Poorly Water-Soluble Drug From Mixed Micellar Solutions of Bile Salt and Lipolysis Products in Rats  

Microsoft Academic Search

The role of a bile salt (sodium taurocholate) and lipolysis products (monoglyceride and fatty acid) in the intestinal absorption of a poorly water-soluble drug, diazepam, was investigated. Absorption rates and bioavailabilities were determined with the in situ rat gut technique of Doluisio et al. and analyzing the diazepam concentrations in the luminal solution, intestinal membrane, blood and lymph. The absorption

A. T. M. Serajuddin; M. Rosoff; A. H. Goldberg

1985-01-01

392

On-line preconcentration/determination of zinc from water, biological and food samples using synthesized chelating resin and flame atomic absorption spectrometry.  

PubMed

An on-line flow injection pre-concentration-flame atomic absorption spectrometry method was developed to determine trace zinc in water (tap, dam, and well water), biological (hair and nail), and liver samples. As a solid phase extractant, a synthesized new chelating resin, poly(2-thiozylmethacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propane sulfonic acid) was used. The resin was characterized by Fourier transform infrared spectroscopy, elemental analysis, and surface area by nitrogen sorption. A pre-concentration factor of 40-fold for a sample volume of 12.6 mL was obtained by using the time-based technique. The detection limit for the pre-concentration method was found to be 2.2 ?g L(-1). The precision (as RSD,%) for 10 replicate determinations at the 0.04 ?g mL(-1) Zn concentration was 1.2%. The calibration graph using the pre-concentration system for zinc was linear with a correlation coefficient of 0.998 in the concentration range from 0.005 to 0.05 ?g mL(-1). The applicability and accuracy of the developed method were estimated by the analysis spiked water, biological, liver samples (83-105%), and also certified reference material TMDA-70 (fortified lake water) and SPS-WW1 Batch 111-Wastewater. The results were in agreement with the certified values. PMID:22981635

Y?lmaz, Sibel; Tokal?o?lu, Serife; Sahan, Serkan; Ulgen, Ahmet; Sahan, Ahmet; Soykan, Cengiz

2013-04-01

393

Feasibility of tropospheric water vapor profiling using infrared heterodyne differential absorption lidar  

SciTech Connect

Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution, acquired over long periods at low operational and maintenance cost, are fundamental to the success of the ARM CART program. The development and verification of realistic climate model parameterizations for clouds and net radiation balance, and the correction of other CART site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. Application of profiles acquired with current techniques, have, to date, been limited by vertical resolution and uniqueness of solution [e.g. high resolution infrared (IR) Fourier transform radiometry], poor spatial and temporal coverage and high operating cost (e.g. radiosondes), or diminished daytime performance, lack of eye-safety, and high maintenance cost (e.g. Raman lidar). Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the study reported here, we develop DIAL system performance models and examine the potential of to solve some of the shortcomings of previous methods using parameterizations representative of current technologies. These models are also applied to diagnose and evaluate other strengths and weaknesses unique to the DIAL method for this application. This work is to continue in the direction of evaluating yet smaller and lower-cost laser diode-based systems for routine monitoring of the lower altitudes using photon counting detection methods. We regard the present report as interim in nature and will update and extend it as a final report at the end of the term of the contract.

Grund, C.J.; Hardesty, R.M. [NOAA Environmental Technology Lab., Boulder, CO (United States); Rye, B.J. [Univ. of Colorado, Boulder, CO (United States). Cooperative Institute for Research in Environmental Sciences (CU/NOAA)

1995-04-03

394

Seed ultrastructure and water absorption pathway of the root-parasitic plant Phelipanche aegyptiaca (Orobanchaceae)  

PubMed Central

Background and Aims Obligate root parasitic plants of the Orobanchaceae do not germinate unless they chemically detect a host plant nearby. Members of this family, like Orobanche, Phelipanche and Striga, are noxious weeds that cause heavy damage to agriculture. In spite of their economic impact, only a few light microscopical studies of their minute seeds have been published, and there is no knowledge of their ultrastructure and of the role each tissue plays during the steps preceding germination. This paper describes the ultrastructure of Phelipanche seeds and contributes to our understanding of seed tissue function. Methods Seeds of P. aegyptiaca were examined under light, scanning electron, transmission electron and fluorescence microscopy following various fixations and staining protocols. The results were interpreted with physiological data regarding mode of water absorption and germination stimulation. Key Results and Conclusions The endothelium, which is the inner layer of the testa, rapidly absorbs water. Its interconnected cells are filled with mucilage and contain labyrinthine walls, facilitating water accumulation for germination that starts after receiving germination stimuli. Swelling of the endothelium leads to opening of the micropyle. The perisperm cells underneath this opening mediate between the rhizosphere and the embryo and are likely to be the location for the receptors of germination stimuli. The other perisperm cells are loaded with lipids and protein bodies, as are the endosperm and parts of the embryo. In the endosperm, the oil bodies fuse with each other while they are intact in the embryo and perisperm. Plasmodesmata connect the perisperm cells to each other, and the cells near the micropyle tightly surround the emerging seedling. These perisperm cells, and also the proximal embryo cells, have dense cytoplasmic contents, and they seem to represent the two seed components that are actively involved in transfer of reserve nutrients to the developing seedling during germination. PMID:22025523

Joel, Daniel M.; Bar, Hilla; Mayer, Alfred M.; Plakhine, Dina; Ziadne, Hammam; Westwood, James H.; Welbaum, Gregory E.

2012-01-01

395

Infrared Reflection Absorption Spectroscopy of Amphipathic Model Peptides at the Air/Water Interface  

PubMed Central

The linear sequence KLAL (KLALKLALKALKAALKLA-NH2) and its corresponding d,l-isomers k9a10-KLAL (KLALKLALkaLKAALKLA-NH2) and l11k12-KLAL (KLALKLALKAlkAALKLA-NH2) are model compounds for potentially amphipathic ?-helical peptides which are able to bind to membranes and to increase the membrane permeability in a structure- and target-dependent manner (Dathe and Wieprecht, 1999) We first studied the secondary structure of KLAL and its analogs bound to the air/water using infrared reflection absorption spectroscopy. For the peptide films the shape and position of the amide I and amide II bands indicate that the KLAL adopts at large areas per molecule an ?-helical secondary structure, whereas at higher surface pressures or smaller areas it converts into a ?-sheet structure. This transition could be observed in the compression isotherm as well as during the adsorption at the air/water interface from the subphase as a function of time. The secondary structures are essentially orientated parallel to the air/water interface. The analogs with d-amino acids in two different positions of the sequence, k9a10-KLAL and l11k12-KLAL, form only ?-sheet structures at all surface pressures. The observed results are interpreted using a comparison of hydrophobic moments calculated for ?-helices and ?-sheets. The differences between the hydrophobic moments calculated using the consensus scale are not large. Using the optimal matching hydrophobicity scale or the whole-residue hydrophobicity scale the ?-sheet even has the larger hydrophobic moment. PMID:15189871

Kerth, Andreas; Erbe, Andreas; Dathe, Margitta; Blume, Alfred

2004-01-01

396

Analysis of Differences in Void Coefficient Predictions for Mixed-Oxide-Fueled Tight-Pitch Light Water Reactor Cells  

SciTech Connect

Analysis of the benchmark problems on the void coefficient of mixed-oxide (MOX)-fueled tight-pitch cells has been performed using the Japanese SRAC code system with the JENDL-3.2 library and the French APOLLO-2 code with the CEA93 library based on JEF-2.2. The benchmark problems have been specified to investigate the physical phenomena occurring during the progressive voidage of MOX-fueled tight-pitch lattices, such as high conversion light water reactor lattices, and to evaluate the impact of nuclear data and calculational methods. Despite the most recently compiled nuclear data libraries and the sophisticated calculation schemes employed in both code systems, the k{sub {infinity}} and void reactivity values obtained by the two code systems show considerable discrepancy especially in the highly voided state. The discrepancy of k{sub {infinity}} values shows an obvious dependence on void fraction and also has been shown to be sensitive to the isotopic composition of plutonium. The observed discrepancies are analyzed by being decomposed into contributing isotopes and reactions and have been shown to be caused by a complicated balance of both negative and positive components, which are mainly attributable to differences in a limited number of isotopes including {sup 239}Pu, {sup 241}Pu, {sup 16}O, and stainless steel.

Unesaki, Hironobu [Kyoto University (Japan); Shiroya, Seiji [Kyoto University (Japan); Kanda, Keiji [Kyoto University (Japan); Cathalau, Stephane [Commissariat a l'Energie Atomique (France); Carre, Franck-Olivier [Commissariat a l'Energie Atomique (France); Aizawa, Otohiko [Musashi Institute of Technology (Japan); Takeda, Toshikazu [Osaka University (Japan)

2000-05-15

397

Distribution coefficients of purine alkaloids in water-ammonium sulfate-alkyl acetate-dialkyl phthalate systems  

NASA Astrophysics Data System (ADS)

The distribution of purine alkaloids (caffeine, theobromine, theophylline) was studied in the systems: alkyl acetates-dialkyl phtalate-salting-out agent (ammonium sulfate). The quantitative characteristics of the extraction-distribution coefficients ( D) and the degree of extraction ( R, %) are calculated. The relationships between the distribution coefficients of alkaloids and the length of the hydrocarbon radical in the molecule of alkyl acetate (dialkyl phtalate) are determined. The possibility of predicting the distribution coefficients is demonstrated.

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

2012-12-01

398

Organic esters of plasticizers affecting the water absorption, adhesive property, glass transition temperature and plasticizer permanence of Eudragit acrylic films  

Microsoft Academic Search

The materials used in film coating technology are very important tools for pharmaceutical applications. The effects of four organic esters used as plasticizers (triacetin, diethyl phthalate (DEP), dibutyl phthalate (DBP) and tributyl citrate (TBC)) on the water absorption behavior and adhesive property of Eudragit films and on the glass transition temperature (Tg) and plasticizer permanence of Eudragit E film were

Shan-Yang Lin; Ko-Shao Chen; Liang Run-Chu

2000-01-01

399

ICG 2000 Amsterdam Glass in the new Millennium Absorption Spectra of Iron and Water in Silicate Glasses  

E-print Network

ICG 2000 Amsterdam ­ Glass in the new Millennium Absorption Spectra of Iron and Water in Silicate Glasses L. Glebov1 , E. Boulos2 1 Center for Research and Education in Optics and Lasers (CREOL), University of Central Florida, Orlando, FL, USA 2 Visteon Glass Systems, Dearborn, MI, USA 1. Introduction

Glebov, Leon

400

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

401

Prediction of 1-octanol-water and air-water partition coefficients for nitro-aromatic compounds from molecular dynamics simulations.  

PubMed

United-atom force fields, based on the Transferable Potentials for Phase Equilibria (TraPPE), are developed for twelve nitro-aromatic compounds, which include 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 3-nitrotoluene (3-NT), 4-nitrotoluene (4-NT), 1,3-dinitrobenzene (1,3-DNB), 1,4-dinitrobenzene (1,4-DNB), 2,4-dinitroanisole (DNAN), 1,3,5-trinitrobenzene (TNB), 2,4,6-trinitrotoluene (TNT), 2-nitroanisole (2-NAN), 4-nitroanisole (4-NAN) and n-methyl-p-nitroaniline (MNA). 1-Octanol-water and air-water partition coefficients are predicted for the optimized TraPPE-UA force field with adaptive biasing force molecular dynamics simulations, and compared to available experimental data. Log Kow values are predicted with an average absolute deviation of 0.2 log units, while Henry's law constants are predicted to with an average absolute deviation of 0.5 log units. Two additional models are presented for energetic materials with five membered rings for which no experimental data are available in the open literature: 3,5-dinitropyrazole (DNP) and 3-nitro-1,2,4-triazole-5-one (NTO). Investigation of the local microstructure around each solute reveals that 1-octanol is able to form hydrogen bonded chains around the solute, while little organized microstructure was observed around the solutes in water. PMID:23529577

Bhatnagar, Navendu; Kamath, Ganesh; Potoff, Jeffrey J

2013-05-01

402

Atmospheric pre-corrected differential absorption techniques to retrieve columnar water vapor: Application to AVIRIS 91/95 data  

SciTech Connect

Water vapor is one of the main forces for weather development as well as for mesoscale air transport processes. The monitoring of water vapor is therefore an important aim in remote sensing of the atmosphere. Current operational systems for water vapor detection use primarily the emission in the thermal infrared (AVHRR, GOES, ATSR, Meteosat) or in the microwave radiation bands (DMSP). The disadvantage of current satellite systems is either a coarse spatial (horizontal) resolution ranging from one to tens of kilometers or a limited insight into the lower atmosphere. Imaging spectrometry on the other hand measures total column water vapor contents at a high spatial horizontal resolution and has therefore the potential of filling these gaps. The sensors of the AVIRIS instrument are capable of acquiring hyperspectral data in 224 bands located in the visible and near infrared at 10 run resolution. This data includes information on constituents of the earth`s surface as well as of the atmosphere. The optical measurement of water vapor can be performed using sensor channels located in bands or lines of the absorption spectrum. The AVIRIS sensor has been used to retrieve water vapor and with less accuracy carbon dioxide, oxygen and ozone. To retrieve the water vapor amount, the so called differential absorption technique has been applied. The goal of this technique is to eliminate background factors by taking a ratio between channels within the absorption band and others besides the band. Various rationing methods on the basis of different channels and calculation techniques were developed. The influence of a trace gas of interest on the radiance at the sensor level is usually simulated by using radiative transfer codes. In this study, spectral transmittance and radiance are calculated by MODTRAN3 simulations with the new DISORT option. This work testS the best performing differential absorption techniques for imaging spectrometry of tropospheric water vapor.

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

1996-03-01

403

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

NASA Technical Reports Server (NTRS)

Water vapor is one of the main forces for weather development as well as for mesoscale air transport processes. The monitoring of water vapor is therefore an important aim in remote sensing of the atmosphere. Current operational systems for water vapor detection use primarily the emission in the thermal infrared (AVHRR, GOES, ATSR, Meteosat) or in the microwave radiation bands (DMSP). The disadvantage of current satellite systems is either a coarse spatial (horizontal) resolution ranging from one to tens of kilometers or a limited insight into the lower atmosphere. Imaging spectrometry on the other hand measures total column water vapor contents at a high spatial horizontal resolution and has therefore the potential of filling these gaps. The sensors of the AVIRIS instrument are capable of acquiring hyperspectral data in 224 bands located in the visible and near infrared at 10 nm resolution. This data includes the information on constituents of the earth's surface as well as of the atmosphere. The optical measurement of water vapor can be performed using sensor channels located in bands or lines of the absorption spectrum. The AVIRIS sensor has been used to retrieve water vapor and with less accuracy carbon dioxide, oxygen and ozone. To retrieve the water vapor amount, the so called differential absorption technique has been applied. The goal of this technique is to eliminate background factors by taking a ratio between channels within the absorption band and others besides the band. Various ratioing methods on the basis of different channels and calculation techniques were developed. The influence of a trace gas of interest on the radiance at the sensor level is usually simulated by using radiative transfer codes. In this study, the spectral transmittance and radiance are calculated by MODTRAN3 simulations with the new DISORT option. The objective of this work is to test the best performing differential absorption techniques for imaging spectrometry of tropospheric water vapor.

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

1996-01-01

404

Determination of blade-to-coolant heat-transfer coefficients on a forced-convection, water-cooled, single-stage turbine  

NASA Technical Reports Server (NTRS)

Blade-to-coolant convective heat-transfer coefficients were obtained on a forced-convection water-cooled single-stage turbine over a large laminar flow range and over a portion of the transition range between laminar and turbulent flow. The convective coefficients were correlated by the general relation for forced-convection heat transfer with laminar flow. Natural-convection heat transfer was negligible for this turbine over the Grashof number range investigated. Comparison of turbine data with stationary tube data for the laminar flow of heated liquids showed good agreement. Calculated average midspan blade temperatures using theoretical gas-to-blade coefficients and blade-to-coolant coefficients from stationary-tube data resulted in close agreement with experimental data.

Freche, John C; Schum, Eugene F

1951-01-01

405

Perfecting a method of micro-analysis of water and acetic acid in a cocoa bean in the course of drying: applying to determine transportation coefficients  

NASA Astrophysics Data System (ADS)

This article is about the study of the diffusion of water and acetic acid in a grain of cocoa in course of drying. The authors present a method of microanalysis which enables the analysis of each little slice of the grain : a precise measurement of each slice is realised in view of the analysis from the centre to the surface of the grain with the aid of a cutting apparatus, designed and realised to this effect. At each instant of the drying process, the profiles of water and acetic acid contents are then determined. A one dimensional diffusion model enables a shell by shell evaluation of the diffusion of water and acid in the cocoa grain. The results obtained show an augmentation of transport coefficients in course of drying. We however observe a decrease of the diffusion coefficient of water to the low moisture content : what makes us think of the appearance of crusting phenomenon.

Nganhou, J.; Njomo, D.; Bénet, J. C.; Augier, F.; Berthomieu, G.

2003-09-01

406

Ultra Narrowband Optical Filters for Water Vapor Differential Absorption Lidar (DIAL) Atmospheric Measurements  

NASA Technical Reports Server (NTRS)

Differential absorption lidar (DIAL) systems are being deployed to make vertical profile measurements of atmospheric water vapor from ground and airborne platforms. One goal of this work is to improve the technology of such DIAL systems that they could be deployed on space-based platforms. Since background radiation reduces system performance, it is important to reduce it. One way to reduce it is to narrow the bandwidth of the optical receiver system. However, since the DIAL technique uses two or more wavelengths, in this case separated by 0.1 nm, a fixed-wavelength narrowband filter that would encompass both wavelengths would be broader than required for each line, approximately 0.02 nm. The approach employed in this project is to use a pair of tunable narrowband reflective fiber Bragg gratings. The Bragg gratings are germanium-doped silica core fiber that is exposed to ultraviolet radiation to produce index-of-refraction changes along the length of the fiber. The gratings can be tuned by stretching. The backscattered laser radiation is transmitted through an optical circulator to the gratings, reflected back to the optical circulator by one of the gratings, and then sent to a photodiode. The filter reflectivities were >90 percent, and the overall system efficiency was 30 percent.

Stenholm, Ingrid; DeYoung, Russell J.

2001-01-01

407

Determination of n-octanol\\/water partition coefficient for DDT-related compounds by RP-HPLC with a novel dual-point retention time correction  

Microsoft Academic Search

n-Octanol\\/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C18 column using methanol–water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (tR) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logkw, the logarithm of

Shu-ying Han; Jun-qin Qiao; Yun-yang Zhang; Li-li Yang; Hong-zhen Lian; Xin Ge; Hong-yuan Chen

2011-01-01