Science.gov

Sample records for absorption rate wba-sar

  1. RF dosimetry: a comparison between power absorption of female and male numerical models from 0.1 to 4 GHz

    NASA Astrophysics Data System (ADS)

    Sandrini, L.; Vaccari, A.; Malacarne, C.; Cristoforetti, L.; Pontalti, R.

    2004-11-01

    Realistic numerical models of human subjects and their surrounding environment represent the basic points of radiofrequency (RF) electromagnetic dosimetry. This also involves differentiating the human models in men and women, possibly with different body shapes and postures. In this context, the aims of this paper are, firstly, to propose a female dielectric anatomical model (fDAM) and, secondly, to compare the power absorption distributions of a male and a female model from 0.1 to 4 GHz. For realizing the fDAM, a magnetic resonance imaging tomographer to acquire images and a recent technique which avoids the discrete segmentation of body tissues into different types have been used. Simulations have been performed with the FDTD method by using a novel filtering-based subgridding algorithm. The latter is applied here for the first time to dosimetry, allowing an abrupt mesh refinement by a factor of up to 7. The results show that the whole-body-averaged specific absorption rate (WBA-SAR) of the female model is higher than that of the male counterpart, mainly because of a thicker subcutaneous fat layer. In contrast, the maximum averaged SAR over 1 g (1gA-SAR) and 10 g (10gA-SAR) does not depend on gender, because it occurs in regions where no subcutaneous fat layer is present.

  2. Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

    PubMed

    Ohtani, Shin; Ushiyama, Akira; Maeda, Machiko; Hattori, Kenji; Kunugita, Naoki; Wang, Jianqing; Ishii, Kazuyuki

    2016-01-01

    We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum. PMID:27665775

  3. Exposure time-dependent thermal effects of radiofrequency electromagnetic field exposure on the whole body of rats.

    PubMed

    Ohtani, Shin; Ushiyama, Akira; Maeda, Machiko; Hattori, Kenji; Kunugita, Naoki; Wang, Jianqing; Ishii, Kazuyuki

    2016-01-01

    We investigated the thermal effects of radiofrequency electromagnetic fields (RF-EMFs) on the variation in core temperature and gene expression of some stress markers in rats. Sprague-Dawley rats were exposed to 2.14 GHz wideband code division multiple access (W-CDMA) RF signals at a whole-body averaged specific absorption rate (WBA-SAR) of 4 W/kg, which causes behavioral disruption in laboratory animals, and 0.4 W/kg, which is the limit for the occupational exposure set by the International Commission on Non-Ionizing Radiation Protection guideline. It is important to understand the possible in vivo effects derived from RF-EMF exposures at these intensities. Because of inadequate data on real-time core temperature analyses using free-moving animal and the association between stress and thermal effects of RF-EMF exposure, we analyzed the core body temperature under nonanesthetic condition during RF-EMF exposure. The results revealed that the core temperature increased by approximately 1.5°C compared with the baseline and reached a plateau till the end of RF-EMF exposure. Furthermore, we analyzed the gene expression of heat-shock proteins (Hsp) and heat-shock transcription factors (Hsf) family after RF-EMF exposure. At WBA-SAR of 4 W/kg, some Hsp and Hsf gene expression levels were significantly upregulated in the cerebral cortex and cerebellum following exposure for 6 hr/day but were not upregulated after exposure for 3 hr/day. On the other hand, there was no significant change in the core temperature and gene expression at WBA-SAR of 0.4 W/kg. Thus, 2.14-GHz RF-EMF exposure at WBA-SAR of 4 W/kg induced increases in the core temperature and upregulation of some stress markers, particularly in the cerebellum.

  4. Correlation between nasal membrane permeability and nasal absorption rate.

    PubMed

    Zhang, Hefei; Lin, Chih-Wei; Donovan, Maureen D

    2013-03-01

    The objective of this study was to investigate the relationship between in vitro permeability (Papp) values obtained from isolated nasal tissues and the absorption rates (ka) of the same compounds following nasal administration in animals and humans. The Papp of a set of 11 drug compounds was measured using animal nasal explants and plasma time-concentration profiles for each of the same compounds following intravenous (IV) and intranasal (IN) administration were experimentally determined or obtained from literature reports. The plasma clearance was estimated from the IV plasma time-concentration profiles, and ka was determined from the IN plasma time-concentration profiles using a deconvolution approach. The level of correlation between Papp and ka was established using Pearson correlation analysis. A good correlation (r=0.77) representing a point-to-point relationship for each of the compounds was observed. This result indicates that the nasal absorption for many drug candidates can be estimated from a readily measured in vitro Papp value. PMID:23225081

  5. Cylindrical waveguide electromagnetic exposure system for biological studies with unrestrained mice at 1.9 GHz.

    PubMed

    Wasoontarajaroen, Siriwat; Thansandote, Artnarong; Gajda, Gregory B; Lemay, Eric P; McNamee, James P; Bellier, Pascale V

    2012-09-01

    This paper presents the development of an in vivo exposure system for exposing small rodents. The system consists of four identical cylindrical waveguide chambers, each with a plastic cage for housing the animal. The chamber is fed by circularly polarized radiofrequency power in the 1.9 GHz cellular frequency band and is vertically mounted so that the long axis of the animal is co-planar with the rotating incident electric field. Power sensors were used along with directional or hybrid couplers and a digital voltmeter for data acquisition for real-time dose rate monitoring. The system was tested to evaluate its dose rate performance when a mouse phantom or a mouse cadaver was inside the cage. The dose rate was quantified in terms of whole-body-average (WBA) specific absorption rate (SAR) per input power using both measurement and computational methods. The exposures of the mouse phantom and cadaver were evaluated for various possible postures and positions. The measurement results showed that the highest WBA-SAR was 16.9 W kg per 1 W incident power when the cadaver was lying prone against the cage wall and the lowest WBA-SAR was 10.4 W kg per 1 W incident power when the cadaver was standing upright in the cage center. These results were found to be in good agreement with those obtained from the computational method. PMID:22850231

  6. Theory of absorption rate of carriers in fused silica under intense laser irradiation

    SciTech Connect

    Deng, Hongxiang; Xiang, Xia; Zheng, WG; Yuan, XD; Wu, SY; Jiang, XD; Gao, Fei; Zu, Xiaotao T.; Sun, Kai

    2010-11-15

    A quantum non-perturbation theory for phonon-assisted photon absorption of conduction band electron in intense laser was developed. By carrying out the calculation in fused silica at wavelengths from ultraviolet to infrared in terawatt intensity laser, we show that the Non-perturbation approach can make a uniform description of energy absorption rate at both short wavelengths and long wavelengths on TW / cm2 intensity laser.

  7. 3D finite element simulation of effects of deflection rate on energy absorption for TRIP steel

    NASA Astrophysics Data System (ADS)

    Hayashi, Asuka; Pham, Hang; Iwamoto, Takeshi

    2015-09-01

    Recently, with the requirement of lighter weight and more safety for a design of automobile, energy absorption capability of structural materials has become important. TRIP (Transformation-induced Plasticity) steel is expected to apply to safety members because of excellent energy absorption capability and ductility. Past studies proved that such excellent characteristics in TRIP steel are dominated by strain-induced martensitic transformation (SIMT) during plastic deformation. Because SIMT strongly depends on deformation rate and temperature, an investigation of the effects of deformation rate and temperature on energy absorption in TRIP is essential. Although energy absorption capability of material can be estimated by J-integral experimentally by using pre-cracked specimen, it is difficult to determine volume fraction of martensite and temperature rise during the crack extension. In addition, their effects on J-integral, especially at high deformation rate in experiment might be quite hard. Thus, a computational prediction needs to be performed. In this study, bending deformation behavior of pre-cracked specimen until the onset point of crack extension are predicted by 3D finite element simulation based on the transformation kinetics model proposed by Iwamoto et al. (1998). It is challenged to take effects of temperature, volume fraction of martensite and deformation rate into account. Then, the mechanism for higher energy absorption characteristic will be discussed.

  8. Measurement of the absorption rate of carbon dioxide into aqueous diethanolamine

    SciTech Connect

    Rowley, R.L.; Adams, M.E.; Marshall, T.L.; Oscarson, J.L.; Wilding, W.V.; Anderson, D.J.

    1998-05-01

    Aqueous alkanolamine solutions are commonly used in natural gas sweetening processes to remove the acid gases CO{sub 2} and H{sub 2}S. Absorption rates of gaseous CO{sub 2} into aqueous diethanolamine (DEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO{sub 2} in solution but very sensitive to the diffusion rate of bicarbonate, protonated DEA, and carbamate ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. The diffusion coefficient of DEA in water was also measured using a Taylor dispersion apparatus. A numerical model was developed and used to regress diffusion coefficients of bicarbonate, carbamate, and protonated amine from measured absorption rates. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate, carbamate, and protonated DEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % DEA in water.

  9. A study of energy absorption rate in a quantum dot and metallic nanosphere hybrid system.

    PubMed

    Schindel, Daniel; Singh, Mahi R

    2015-09-01

    We have studied energy absorption rate in a quantum dot-metallic nanosphere system embedded on a dielectric substrate. We applied a control field to induce dipole moments in the quantum dot and the metal nanosphere, and monitored the energy absorption using a probe field. These external fields induce dipole moments in the metal nanosphere and the quantum dot, and these two structures interact with one another via the dipole-dipole interaction. The density matrix method was used to evaluate the absorption, indicating that it can be shifted by moving the metal nanosphere close to the quantum dot. Also, absorption efficiency can either be quenched or enhanced by the addition of a metal nanosphere. This hybrid system can be used to create ultrafast switching and sensing nanodevices.

  10. A study of energy absorption rate in a quantum dot and metallic nanosphere hybrid system

    NASA Astrophysics Data System (ADS)

    Schindel, Daniel; Singh, Mahi R.

    2015-09-01

    We have studied energy absorption rate in a quantum dot-metallic nanosphere system embedded on a dielectric substrate. We applied a control field to induce dipole moments in the quantum dot and the metal nanosphere, and monitored the energy absorption using a probe field. These external fields induce dipole moments in the metal nanosphere and the quantum dot, and these two structures interact with one another via the dipole-dipole interaction. The density matrix method was used to evaluate the absorption, indicating that it can be shifted by moving the metal nanosphere close to the quantum dot. Also, absorption efficiency can either be quenched or enhanced by the addition of a metal nanosphere. This hybrid system can be used to create ultrafast switching and sensing nanodevices.

  11. Energy absorption at high strain rate of glass fiber reinforced mortars

    NASA Astrophysics Data System (ADS)

    Fenu, Luigi; Forni, Daniele; Cadoni, Ezio

    2015-09-01

    In this paper, the dynamic behaviour of cement mortars reinforced with glass fibers was studied. The influence of the addition of glass fibers on energy absorption and tensile strength at high strain-rate was investigated. Static tests in compression, in tension and in bending were first performed. Dynamic tests by means of a Modified Hopkinson Bar were then carried out in order to investigate how glass fibers affected energy absorption and tensile strength at high strain-rate of the fiber reinforced mortar. The Dynamic Increase Factor (DIF) was finally evaluated.

  12. A review of lung-to-blood absorption rates for radon progeny.

    PubMed

    Marsh, J W; Bailey, M R

    2013-12-01

    The International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model (HRTM) treats clearance of materials from the respiratory tract as a competitive process between absorption into blood and particle transport to the alimentary tract and lymphatics. The ICRP recommended default absorption rates for lead and polonium (Type M) in ICRP Publication 71 but stated that the values were not appropriate for short-lived radon progeny. This paper reviews and evaluates published data from volunteer and laboratory animal experiments to estimate the HRTM absorption parameter values for short-lived radon progeny. Animal studies showed that lead ions have two phases of absorption: ∼10 % absorbed with a half-time of ∼15 min, the rest with a half-time of ∼10 h. The studies also indicated that some of the lead ions were bound to respiratory tract components. Bound fractions, f(b), for lead were estimated from volunteer and animal studies and ranged from 0.2 to 0.8. Based on the evaluations of published data, the following HRTM absorption parameter values were derived for lead as a decay product of radon: f(r) = 0.1, s(r) = 100 d(-1), s(s) = 1.7 d(-1), f(b) = 0.5 and s(b) = 1.7 d(-1). Effective doses calculated assuming these absorption parameter values instead of a single absorption half-time of 10 h with no binding (as has generally been assumed) are only a few per cent higher. However, as there is some conflicting evidence on the absorption kinetics for radon progeny, dose calculations have been carried out for different sets of absorption parameter values derived from different studies. The results of these calculations are discussed.

  13. Mechanism and rate of glucose absorption differ between an Australian honeyeater (Meliphagidae) and a lorikeet (Loriidae).

    PubMed

    Napier, Kathryn R; McWhorter, Todd J; Fleming, Patricia A

    2008-11-01

    Efficient mechanisms of glucose absorption are necessary for volant animals as a means of reducing mass during flight: they speed up gut transit time and require smaller volume and mass of gut tissue. One mechanism that may be important is absorption via paracellular (non-mediated) pathways. This may be particularly true for nectarivorous species which encounter large quantities of sugar in their natural diet. We investigated the extent of mediated and non-mediated glucose absorption in red wattlebirds Anthochaera carunculata (Meliphagidae) and rainbow lorikeets Trichoglossus haematodus (Loriidae) to test the hypothesis that paracellular uptake accounts for a significant proportion of total glucose uptake in these species. We found that routes of glucose absorption are highly dynamic in both species. In lorikeets, absorption of L-glucose (non-mediated uptake) is slower than that of D-glucose (mediated and non-mediated uptake), with as little as 10% of total glucose absorbed by the paracellular pathway initially (contrasting previous indirect estimates of approximately 80%). Over time, however, more glucose may be absorbed via the paracellular route. Glucose absorption by both mediated and non-mediated mechanisms in wattlebirds occurred at a faster rate than in lorikeets, and wattlebirds also rely substantially on paracellular uptake. In wattlebirds, we recorded higher bioavailability of L-glucose (96+/-3%) compared with D-glucose (57+/-2%), suggesting problems with the in vivo use of radiolabeled d-glucose. Further trials with 3-O-methyl-D-glucose revealed high bioavailability in wattlebirds (90+/-5%). This non-metabolisable glucose analogue remains the probe of choice for measuring uptake rates in vivo, especially in birds in which absorption and metabolism occur extremely rapidly.

  14. Mechanism and rate of glucose absorption differ between an Australian honeyeater (Meliphagidae) and a lorikeet (Loriidae).

    PubMed

    Napier, Kathryn R; McWhorter, Todd J; Fleming, Patricia A

    2008-11-01

    Efficient mechanisms of glucose absorption are necessary for volant animals as a means of reducing mass during flight: they speed up gut transit time and require smaller volume and mass of gut tissue. One mechanism that may be important is absorption via paracellular (non-mediated) pathways. This may be particularly true for nectarivorous species which encounter large quantities of sugar in their natural diet. We investigated the extent of mediated and non-mediated glucose absorption in red wattlebirds Anthochaera carunculata (Meliphagidae) and rainbow lorikeets Trichoglossus haematodus (Loriidae) to test the hypothesis that paracellular uptake accounts for a significant proportion of total glucose uptake in these species. We found that routes of glucose absorption are highly dynamic in both species. In lorikeets, absorption of L-glucose (non-mediated uptake) is slower than that of D-glucose (mediated and non-mediated uptake), with as little as 10% of total glucose absorbed by the paracellular pathway initially (contrasting previous indirect estimates of approximately 80%). Over time, however, more glucose may be absorbed via the paracellular route. Glucose absorption by both mediated and non-mediated mechanisms in wattlebirds occurred at a faster rate than in lorikeets, and wattlebirds also rely substantially on paracellular uptake. In wattlebirds, we recorded higher bioavailability of L-glucose (96+/-3%) compared with D-glucose (57+/-2%), suggesting problems with the in vivo use of radiolabeled d-glucose. Further trials with 3-O-methyl-D-glucose revealed high bioavailability in wattlebirds (90+/-5%). This non-metabolisable glucose analogue remains the probe of choice for measuring uptake rates in vivo, especially in birds in which absorption and metabolism occur extremely rapidly. PMID:18978218

  15. Rate- and Extent-Limiting Factors of Oral Drug Absorption: Theory and Applications.

    PubMed

    Sugano, Kiyohiko; Terada, Katsuhide

    2015-09-01

    The oral absorption of drugs has been represented by various concepts such as the absorption potential, the maximum absorbable dose, the biopharmaceutics classification system, and in vitro-in vivo correlation. The aim of this article is to provide an overview of the theoretical relationships between these concepts. It shows how a simple analytical solution for the fraction of a dose absorbed (Fa equation) can offer a theoretical base to tie together the various concepts, and discusses how this solution relates to the rate-limiting cases of oral drug absorption. The article introduces the Fa classification system as a framework in which all the above concepts were included, and discusses its applications for food effect prediction, active pharmaceutical ingredient form selection, formulation design, and biowaiver strategy.

  16. Mass Loss Rates for Solar-like Stars Measured from Lyα Absorption

    NASA Astrophysics Data System (ADS)

    Wood, B. E.; Müller, H.-R.; Linsky, J. L.

    2003-10-01

    We present a number of mass loss rate measurements for solar-like stars with coronal winds, computed using a Lyα absorption technique. The collision between the solar wind and the interstellar wind seen by the Sun defines the large scale structure of our heliosphere. Similar structures, ``astrospheres,'' exist around other solar-like stars. The deceleration of the interstellar wind at the solar or stellar bow shock heats the interstellar material. Heated neutral hydrogen in the outer astrosphere (and/or heliosphere) produces a broad Lyα absorption profile that is often detectable in high resolution Hubble Space Telescope spectra. The amount of absorption is dependent upon the strength of the stellar wind. With guidance from hydrodynamic models of astrospheres, we use detected astrospheric Lyα absorption to estimate the stellar mass loss rates. For the solar-like GK stars in our sample, mass loss appears to increase with stellar activity, suggesting that young, active stars have stronger winds than old, inactive stars. However, Proxima Cen (M5.5 Ve) and λ And (G8 IV-III+M V) appear to be inconsistent with this relation.

  17. Specific absorption rate determination of magnetic nanoparticles through hyperthermia measurements in non-adiabatic conditions

    NASA Astrophysics Data System (ADS)

    Coïsson, M.; Barrera, G.; Celegato, F.; Martino, L.; Vinai, F.; Martino, P.; Ferraro, G.; Tiberto, P.

    2016-10-01

    An experimental setup for magnetic hyperthermia operating in non-adiabatic conditions is described. A thermodynamic model that takes into account the heat exchanged by the sample with the surrounding environment is developed. A suitable calibration procedure is proposed that allows the experimental validation of the model. Specific absorption rate can then be accurately determined just from the measurement of the sample temperature at the equilibrium steady state. The setup and the measurement procedure represent a simplification with respect to other systems requiring calorimeters or crucial corrections for heat flow. Two families of magnetic nanoparticles, one superparamagnetic and one characterised by larger sizes and static hysteresis, have been characterised as a function of field intensity, and specific absorption rate and intrinsic loss power have been obtained.

  18. Specific absorption rate analysis of broadband mobile antenna with negative index metamaterial

    NASA Astrophysics Data System (ADS)

    Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2016-03-01

    This paper presents a negative index metamaterial-inspired printed mobile wireless antenna that can support most mobile applications such as GSM, UMTS, Bluetooth and WLAN frequency bands. The antenna consists of a semi-circular patch, a 50Ω microstrip feed line and metamaterial ground plane. The antenna occupies a very small space of 37 × 47 × 0.508 mm3, making it suitable for mobile wireless application. The perceptible novelty shown in this proposed antenna is that reduction of specific absorption rate using the negative index metamaterial ground plane. The proposed antenna reduced 72.11 and 75.53 % of specific absorption rate at 1.8 and 2.4 GHz, respectively.

  19. Absorption cross-section and decay rate of rotating linear dilaton black holes

    NASA Astrophysics Data System (ADS)

    Sakalli, I.; Aslan, O. A.

    2016-02-01

    We analytically study the scalar perturbation of non-asymptotically flat (NAF) rotating linear dilaton black holes (RLDBHs) in 4-dimensions. We show that both radial and angular wave equations can be solved in terms of the hypergeometric functions. The exact greybody factor (GF), the absorption cross-section (ACS), and the decay rate (DR) for the massless scalar waves are computed for these black holes (BHs). The results obtained for ACS and DR are discussed through graphs.

  20. Laser absorption, mass ablation rate, and shock heating in direct-drive inertial confinement fusiona)

    NASA Astrophysics Data System (ADS)

    Regan, S. P.; Epstein, R.; Goncharov, V. N.; Igumenshchev, I. V.; Li, D.; Radha, P. B.; Sawada, H.; Seka, W.; Boehly, T. R.; Delettrez, J. A.; Gotchev, O. V.; Knauer, J. P.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Sangster, T. C.; Shvarts, D.; Skupsky, S.; Smalyuk, V. A.; Yaakobi, B.; Mancini, R. C.

    2007-05-01

    Direct-drive laser absorption, mass ablation rate, and shock heating are experimentally studied on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] to validate hydrodynamics simulations. High-gain, direct-drive inertial confinement fusion target implosions require accurate predictions of the shell adiabat α (entropy), defined as the pressure in the main fuel layer to the Fermi-degenerate pressure, and the implosion velocity of the shell. The laser pulse shape determines the shell adiabat and the hydrodynamic efficiency determines the implosion velocity. A comprehensive set of measurements tracking the flow of energy from the laser to the target was conducted. Time-resolved measurements of laser absorption in the corona are performed on spherical implosion experiments. The mass ablation rate is inferred from time-resolved Ti K-shell spectroscopic measurements of nonaccelerating, solid CH spherical targets with a buried tracer layer of Ti. Shock heating is diagnosed in planar-CH-foil targets using time-resolved x-ray absorption spectroscopy and noncollective spectrally resolved x-ray scattering. The highly reproducible experimental results achieved with a high level of laser drive uniformity [S. P. Regan et al., J. Opt. Soc. Am. B 22, 998 (2005)] constrain the modeling of direct-drive energy coupling. A detailed comparison of the experimental results and the simulations reveals that a single-value flux limiter in the thermal transport model cannot explain all of the experimental observables. Simulations of laser absorption measurements need a time-dependent flux limiter to match the data. Modeling of both resonance absorption and nonlocal effects in the electron thermal conduction from the critical density to the ablation front are underway to resolve the observed discrepancies.

  1. Strain Rate Effects on the Energy Absorption of Rapidly Manufactured Composite Tubes

    SciTech Connect

    Brighton, Aaron M; Forrest, Mark; Starbuck, J Michael; ERDMAN III, DONALD L; Fox, Bronwyn

    2009-01-01

    Quasi-static and intermediate rate axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). The quasi-static tests were conducted at 10 mm/min (1.67x10-4 m/s); five different crush initiators were used. Tests at intermediate rates were performed at speeds of 0.25 m/s, 0.5 m/s, 0.75 m/s 1m/s, 2 m/s and 4 m/s. Quasi-static tests of tubular specimens showed high specific energy absorption (SEA) values with 86 kJ/kg for Carbon/Epoxy specimens. The specific energy absorption of the Glass/Polypropylene specimens was measured to be 29 kJ/kg. Results from the intermediate test rates showed that while a decrease in specific energy absorbed was observed as speeds increased, values did not fall below 55kj/kg for carbon specimens or 35 kJ/kg for the Glass/Polypropylene specimens. When compared with steel and aluminium, specific energy absorption values of 15 kJ/kg and 30 kJ/kg respectively, the benefits of using composite materials in crash structures are apparent.

  2. Effective absorption cross sections and photolysis rates of anthropogenic and biogenic secondary organic aerosols

    NASA Astrophysics Data System (ADS)

    Romonosky, Dian E.; Ali, Nujhat N.; Saiduddin, Mariyah N.; Wu, Michael; Lee, Hyun Ji (Julie); Aiona, Paige K.; Nizkorodov, Sergey A.

    2016-04-01

    Mass absorption coefficient (MAC) values were measured for secondary organic aerosol (SOA) samples produced by flow tube ozonolysis and smog chamber photooxidation of a wide range of volatile organic compounds (VOC), specifically: α-pinene, β-pinene, β-myrcene, d-limonene, farnesene, guaiacol, imidazole, isoprene, linalool, ocimene, p-xylene, 1-methylpyrrole, and 2-methylpyrrole. Both low-NOx and high-NOx conditions were employed during the chamber photooxidation experiments. MAC values were converted into effective molecular absorption cross sections assuming an average molecular weight of 300 g/mol for SOA compounds. The upper limits for the effective photolysis rates of SOA compounds were calculated by assuming unity photolysis quantum yields and convoluting the absorption cross sections with a time-dependent solar spectral flux. A more realistic estimate for the photolysis rates relying on the quantum yield of acetone was also obtained. The results show that condensed-phase photolysis of SOA compounds can potentially occur with effective lifetimes ranging from minutes to days, suggesting that photolysis is an efficient and largely overlooked mechanism of SOA aging.

  3. Influence of light absorption rate by Nannochloropsis oculata on triglyceride production during nitrogen starvation.

    PubMed

    Kandilian, Razmig; Pruvost, Jérémy; Legrand, Jack; Pilon, Laurent

    2014-07-01

    This study aims to understand the role of light transfer in triglyceride fatty-acid (TG-FA) cell content and productivity from microalgae during nitrogen starvation. Large amounts of TG-FA can be produced via nitrogen starvation of microalgae in photobioreactors exposed to intense light. First, spectral absorption and scattering cross-sections of N. oculata were measured at different times during nitrogen starvation. They were used to relate the mean volumetric rate of energy absorption (MVREA) per unit mass of microalgae to the TG-FA productivity and cell content. TG-FA productivity correlated with the MVREA and reached a maximum for MVREA of 13 μmol hν/gs. This indicated that TG-FA synthesis was limited by the photon absorption rate in the PBR. A minimum MVREA of 13 μmol hν/gs was also necessary at the onset of nitrogen starvation to trigger large accumulation of TG-FA in cells. These results will be instrumental in defining protocols for TG-FA production in scaled-up photobioreactors.

  4. Determination of methane emission rates on a biogas plant using data from laser absorption spectrometry.

    PubMed

    Groth, Angela; Maurer, Claudia; Reiser, Martin; Kranert, Martin

    2015-02-01

    The aim of the work was to establish a method for emission control of biogas plants especially the observation of fugitive methane emissions. The used method is in a developmental stage but the topic is crucial to environmental and economic issues. A remote sensing measurement method was adopted to determine methane emission rates of a biogas plant in Rhineland-Palatinate, Germany. An inverse dispersion model was used to deduce emission rates. This technique required one concentration measurement with an open path tunable diode laser absorption spectrometer (TDLAS) downwind and upwind the source and basic wind information, like wind speed and direction. Different operating conditions of the biogas plant occurring on the measuring day (December 2013) could be represented roughly in the results. During undisturbed operational modes the methane emission rate averaged 2.8 g/s, which corresponds to 4% of the methane gas production rate of the biogas plant.

  5. New constraints in absorptive capacity and the optimum rate of petroleum output

    SciTech Connect

    El Mallakh, R

    1980-01-01

    Economic policy in four oil-producing countries is analyzed within a framework that combines a qualitative assessment of the policy-making process with an empirical formulation based on historical and current trends in these countries. The concept of absorptive capacity is used to analyze the optimum rates of petroleum production in Iran, Iraq, Saudi Arabia, and Kuwait. A control solution with an econometric model is developed which is then modified for alternative development strategies based on analysis of factors influencing production decisions. The study shows the consistencies and inconsistencies between the goals of economic growth, oil production, and exports, and the constraints on economic development. Simulation experiments incorporated a number of the constraints on absorptive capacity. Impact of other constraints such as income distribution and political stability is considered qualitatively. (DLC)

  6. Specific absorption rate calculations of magnetite, using a modified linear response model for applications in magnetic hyperthermia

    SciTech Connect

    Hernández S, A. E-mail: meduardo2001@hotmail.com; Cano, M. E. E-mail: meduardo2001@hotmail.com; Torres-Arenas, J.

    2014-11-07

    Currently the absorption of electromagnetic radiation by magnetic nanoparticles is studied for biomedical applications of cancer thermotherapy. Several experiments are conduced following the framework of the Rosensweig model, in order to estimate their specific absorption rate. Nevertheless, this linear approximation involves strong simplifications which constrain their accuracy and validity range. The main aim of this work is to incorporate the deviation of the sphericity assumption in particles shapes, to improve the determination of their specific absorption rate. The correction to the effective particles volume is computed as a measure of the apparent amount of magnetic material, interacting with the external AC magnetic field. Preliminary results using the physical properties of Fe3O4 nanoparticles, exhibit an important correction in their estimated specific absorption rate, as a function of the apparent mean particles radius. Indeed, we have observed using a small deviation (6% of the apparent radius), up to 40% of the predicted specific absorption rate by the Rosensweig linear approximation.

  7. Simplified segmented human models for whole body and localised SAR evaluation of 20 MHz to 6 GHz electromagnetic field exposures.

    PubMed

    Wu, Tongning; Shao, Qing; Yang, Lei

    2013-03-01

    The digital human model is a key element in evaluating the electromagnetic field (EMF) exposure. This paper proposes the application of simplified segmented human models for EMF exposure compliance evaluation with the whole body and the localised limits. The method is based on the fact that most of the EMF power absorption is concentrated in several major tissues. Two kinds of human models were simply (the proposed method) and precisely segmented from two sets of whole body magnetic resonance imaging (MRI) scanned images. The whole body average-specific absorption rate (WBA-SAR) and the peak localised SAR averaging over 10 g tissues for the two kinds of models are calculated for various exposure configurations. The results confirmed the efficiency and the validity of the proposed method. The application as evaluating the MRI radiofrequency EMF exposure is also discussed in the paper.

  8. Bit rate transparent interferometric noise mitigation utilizing the nonlinear modulation curve of electro-absorption modulator.

    PubMed

    Feng, Hanlin; Xiao, Shilin; Fok, Mable P

    2015-08-24

    we propose a bit-rate transparent interferometric noise mitigation scheme utilizing the nonlinear modulation curve of electro-absorption modulator (EAM). Both the zero-slope region and the linear modulation region of the nonlinear modulation curve are utilized to suppress interferometric noise and enlarge noise margin of degraded eye diagrams. Using amplitude suppression effect of the zero-slope region, interferometric noise at low frequency range is suppressed successfully. Under different signal to noise ratio (SNR), we measured the power penalties at bit error rate (BER) of 10<(-9) with and without EAM interferometric noise suppression. By using our proposed scheme, power penalty improvement of 8.5 dB is achieved in a signal with signal-to-noise ratio of 12.5 dB. BER results at various bit rates are analyzed, error floors for each BER curves are removed, significantly improvement in receiver sensitivity and widely opened eye diagrams are resulted.

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

    PubMed

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

    2013-07-15

    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 μg 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.

  10. OH reaction rate constants and UV absorption cross-sections of unsaturated esters

    NASA Astrophysics Data System (ADS)

    Teruel, M. A.; Lane, S. I.; Mellouki, A.; Solignac, G.; Le Bras, G.

    Absolute rate coefficients have been determined for the gas-phase reactions of hydroxyl radicals with methyl acrylate ( k1), methyl methacrylate ( k2) and ethyl acrylate ( k3). Experiments were performed using two different techniques, the relative rate method and the pulsed laser photolysis-laser induced fluorescence technique. The kinetic data obtained were used to derive the following Arrhenius expressions in the temperature range 253-374 K (in units of cm 3 molecule -1 s -1): k1=(2.0±0.8)×10exp[(553±51)/T], k2=(2.5±0.8)×10exp[(821±55)/T], k3=(2.3±0.8)×10exp[(580±65)/T]. At 298 K, the reaction rate constants obtained by the two methods were in good agreement. In addition, the UV absorption spectra for the three unsaturated esters have been determined at (298±2) K and the absorption cross-sections in the wavelength region 215-298 nm were reported. The results are presented, discussed and used to estimate the atmospheric lifetimes for the studied esters.

  11. The absorption efficiency and respiration rate of the Florida lancelet, Branchiostoma floridae.

    PubMed

    Nash, Troy R; Ruppert, Edward E; Colacino, James M

    2009-12-01

    The present study investigates some aspects of the digestive biology and physiological energetics of the Florida lancelet, Branchiostoma floridae. Florida lancelets are able to remove 47.2-56.9% of the energy from a diet of mixed algae. The respiration rate is 0.100mL O(2) (STPD) h(-1) g(-1) (wet), which estimates a metabolic rate of 0.248 J h(-1), at an average body mass of 0.125 g (wet). Published values of the chlorophyll a concentration in its natural habitat indicate that a 125 mg lancelet would need to filter 0.018-0.031 L h(-1) to remove sufficient food to support its resting metabolism. The filtration rate of lancelets has been reported as 0.138 L h(-1), indicating that the actual filtration rate is 4-7 times greater than the filtration rate needed to meet resting metabolic demands. It appears that lancelets have the potential to be raised in aquaculture, because their absorption efficiency and respiration rate are comparable to suspension-feeding invertebrates that have been successfully aquacultured.

  12. Elementary reaction rate measurements at high temperatures by tunable-laser flash-absorption

    SciTech Connect

    Hessler, J.P.

    1993-12-01

    The major objective of this program is to measure thermal rate coefficients and branching ratios of elementary reactions. To perform these measurements, the authors constructed an ultrahigh-purity shock tube to generate temperatures between 1000 and 5500 K. The tunable-laser flash-absorption technique is used to measure the rate of change of the concentration of species which absorb below 50,000 cm{sup {minus}1} e.g.: OH, CH, and CH{sub 3}. This technique is being extended into the vacuum-ultraviolet spectral region where one can measure atomic species e.g.: H, D, C, O, and N; and diatomic species e.g.: O{sub 2}, CO, and OH.

  13. Prostaglandin E2 regulation of amnion cell vascular endothelial growth factor expression: relationship with intramembranous absorption rate in fetal sheep.

    PubMed

    Cheung, Cecilia Y; Beardall, Michael K; Anderson, Debra F; Brace, Robert A

    2014-08-01

    We hypothesized that prostaglandin E2 (PGE2) stimulates amniotic fluid transport across the amnion by upregulating vascular endothelial growth factor (VEGF) expression in amnion cells and that amniotic PGE2 concentration correlates positively with intramembranous (IM) absorption rate in fetal sheep. The effects of PGE2 at a range of concentrations on VEGF 164 and caveolin-1 gene expressions were analyzed in cultured ovine amnion cells. IM absorption rate, amniotic fluid (AF) volume, and PGE2 concentration in AF were determined in late-gestation fetal sheep during control conditions, isovolumic fetal urine replacement (low IM absorption rate), or intra-amniotic fluid infusion (high IM absorption rate). In ovine amnion cells, PGE2 induced dose- and time-dependent increases in VEGF 164 mRNA levels and reduced caveolin-1 mRNA and protein levels. VEGF receptor blockade abolished the caveolin-1 response, while minimally affecting the VEGF response to PGE2. In sheep fetuses, urine replacement reduced amniotic PGE2 concentration by 58%, decreased IM absorption rate by half, and doubled AF volume (P < 0.01). Intra-amniotic fluid infusion increased IM absorption rate and AF volume (P < 0.01), while amniotic PGE2 concentration was unchanged. Neither IM absorption rate nor AF volume correlated with amniotic PGE2 concentration under each experimental condition. Although PGE2 at micromolar concentrations induced dose-dependent responses in VEGF and caveolin-1 gene expression in cultured amnion cells consistent with a role of PGE2 in activating VEGF to mediate AF transport across the amnion, amniotic PGE2 at physiological nanomolar concentrations does not appear to regulate IM absorption rate or AF volume.

  14. Aquaporins in ovine amnion: responses to altered amniotic fluid volumes and intramembranous absorption rates.

    PubMed

    Cheung, Cecilia Y; Anderson, Debra F; Brace, Robert A

    2016-07-01

    Aquaporins (AQPs) are transmembrane channel proteins that facilitate rapid water movement across cell membranes. In amniotic membrane, the AQP-facilitated transfer of water across amnion cells has been proposed as a mechanism for amniotic fluid volume (AFV) regulation. To investigate whether AQPs modulate AFV by altering intramembranous absorption (IMA) rate, we tested the hypothesis that AQP gene expression in the amnion is positively correlated with IMA rate during experimental conditions when IMA rate and AFV are modified over a wide range. The relative abundances of AQP1, AQP3, AQP8, AQP9, and AQP11 mRNA and protein were determined in the amnion of 16 late-gestation ovine fetuses subjected to 2 days of control conditions, urine drainage, urine replacement, or intraamniotic fluid infusion. AQP mRNA levels were determined by RT-qPCR and proteins by western immunoblot. Under control conditions, mRNA levels among the five AQPs differed more than 20-fold. During experimental treatments, mean IMA rate in the experimental groups ranged from 100 ± 120 mL/day to 1370 ± 270 mL/day. The mRNA levels of the five AQPs did not change from control and were not correlated with IMA rates. The protein levels of AQP1 were positively correlated with IMA rates (r(2) = 38%, P = 0.01) while the remaining four AQPs were not. These findings demonstrate that five AQPs are differentially expressed in ovine amnion. Our study supports the hypothesis that AQP1 may play a positive role in regulating the rate of fluid transfer across the amnion, thereby participating in the dynamic regulation of AFV.

  15. Aquaporins in ovine amnion: responses to altered amniotic fluid volumes and intramembranous absorption rates.

    PubMed

    Cheung, Cecilia Y; Anderson, Debra F; Brace, Robert A

    2016-07-01

    Aquaporins (AQPs) are transmembrane channel proteins that facilitate rapid water movement across cell membranes. In amniotic membrane, the AQP-facilitated transfer of water across amnion cells has been proposed as a mechanism for amniotic fluid volume (AFV) regulation. To investigate whether AQPs modulate AFV by altering intramembranous absorption (IMA) rate, we tested the hypothesis that AQP gene expression in the amnion is positively correlated with IMA rate during experimental conditions when IMA rate and AFV are modified over a wide range. The relative abundances of AQP1, AQP3, AQP8, AQP9, and AQP11 mRNA and protein were determined in the amnion of 16 late-gestation ovine fetuses subjected to 2 days of control conditions, urine drainage, urine replacement, or intraamniotic fluid infusion. AQP mRNA levels were determined by RT-qPCR and proteins by western immunoblot. Under control conditions, mRNA levels among the five AQPs differed more than 20-fold. During experimental treatments, mean IMA rate in the experimental groups ranged from 100 ± 120 mL/day to 1370 ± 270 mL/day. The mRNA levels of the five AQPs did not change from control and were not correlated with IMA rates. The protein levels of AQP1 were positively correlated with IMA rates (r(2) = 38%, P = 0.01) while the remaining four AQPs were not. These findings demonstrate that five AQPs are differentially expressed in ovine amnion. Our study supports the hypothesis that AQP1 may play a positive role in regulating the rate of fluid transfer across the amnion, thereby participating in the dynamic regulation of AFV. PMID:27440743

  16. Effective light absorption and absolute electron transport rates in the coral Pocillopora damicornis.

    PubMed

    Szabó, Milán; Wangpraseurt, Daniel; Tamburic, Bojan; Larkum, Anthony W D; Schreiber, Ulrich; Suggett, David J; Kühl, Michael; Ralph, Peter J

    2014-10-01

    Pulse Amplitude Modulation (PAM) fluorometry has been widely used to estimate the relative photosynthetic efficiency of corals. However, both the optical properties of intact corals as well as past technical constrains to PAM fluorometers have prevented calculations of the electron turnover rate of PSII. We used a new Multi-colour PAM (MC-PAM) in parallel with light microsensors to determine for the first time the wavelength-specific effective absorption cross-section of PSII photochemistry, σII(λ), and thus PAM-based absolute electron transport rates of the coral photosymbiont Symbiodinium both in culture and in hospite in the coral Pocillopora damicornis. In both cases, σII of Symbiodinium was highest in the blue spectral region and showed a progressive decrease towards red wavelengths. Absolute values for σII at 440 nm were up to 1.5-times higher in culture than in hospite. Scalar irradiance within the living coral tissue was reduced by 20% in the blue when compared to the incident downwelling irradiance. Absolute electron transport rates of P. damicornis at 440 nm revealed a maximum PSII turnover rate of ca. 250 electrons PSII(-1) s(-1), consistent with one PSII turnover for every 4 photons absorbed by PSII; this likely reflects the limiting steps in electron transfer between PSII and PSI. Our results show that optical properties of the coral host strongly affect light use efficiency of Symbiodinium. Therefore, relative electron transport rates do not reflect the productivity rates (or indeed how the photosynthesis-light response is parameterised). Here we provide a non-invasive approach to estimate absolute electron transport rates in corals.

  17. Fe /Fe oxide nanocomposite particles with large specific absorption rate for hyperthermia

    NASA Astrophysics Data System (ADS)

    Zeng, Q.; Baker, I.; Loudis, J. A.; Liao, Y.; Hoopes, P. J.; Weaver, J. B.

    2007-06-01

    Using a water-in-oil microemulsion with cetyl trimethyl ammonium bromide as the surfactant, iron was reduced to form a metallic core on which a passivating oxide shell was grown. Transmission electron microscopy, vibrating sample magnetometry, and heating measurements were used to characterize these monodispersed magnetic Fe /Fe3O4 composite nanoparticles with respect to the possible application for magnetic hyperthermia treatments of cancer. The aim is to utilize the fact that an iron core (high saturation magnetization) will give a greater heating effect than iron oxide, while the iron oxide coating will allow the nanoparticles to be observed using magnetic resonance imaging so that therapy can be effectively monitored and targeted. The largest specific absorption rate obtained was 345W/g under an alternating magnetic field of 150Oe at 250kHz.

  18. Specific absorption rate in models of man and monkey at 225 and 2000 MHz

    SciTech Connect

    Olsen, R.G.; Griner, T.A.

    1987-01-01

    Full-size models of a man and a rhesus monkey were exposed to radiofrequency (RF) radiation at 225 MHz. The model of man was also exposed to 2000 MHz. Specific absorption rates (SARs) were measured in partial-body sections, such as the arms, legs, etc., using gradient-layer calorimeters. Also, front-surface thermographic images were obtained to qualitatively show the heating patterns. For all of the configurations used, the SAR in the limbs was much higher than in the torso. Agreement (whole-body SARs) with spheroidal models was better for both models at 225 MHz than at 2000 MHz. These results indicate that in the frequency range two orders of magnitude above whole-body resonance, SAR in the limbs significantly contributes to the whole-body average SAR.

  19. Magnetic Nanoparticles with High Specific Absorption Rate at Low Alternating Magnetic Field

    PubMed Central

    Kekalo, K.; Baker, I.; Meyers, R.; Shyong, J.

    2015-01-01

    This paper describes the synthesis and properties of a new type of magnetic nanoparticle (MNP) for use in the hyperthermia treatment of tumors. These particles consist of 2–4 nm crystals of gamma-Fe2O3 gathered in 20–40 nm aggregates with a coating of carboxymethyl-dextran, producing a zetasize of 110–120 nm. Despite their very low saturation magnetization (1.5–6.5 emu/g), the specific absorption rate (SAR) of the nanoparticles is 22–200 W/g at applied alternating magnetic field (AMF) with strengths of 100–500 Oe at a frequency of 160 kHz. PMID:26884816

  20. MRI-based anatomical model of the human head for specific absorption rate mapping

    PubMed Central

    Makris, Nikos; Angelone, Leonardo; Tulloch, Seann; Sorg, Scott; Kaiser, Jonathan; Kennedy, David

    2009-01-01

    In this study, we present a magnetic resonance imaging (MRI)-based, high-resolution, numerical model of the head of a healthy human subject. In order to formulate the model, we performed quantitative volumetric segmentation on the human head, using T1-weighted MRI. The high spatial resolution used (1 × 1 × 1 mm3), allowed for the precise computation and visualization of a higher number of anatomical structures than provided by previous models. Furthermore, the high spatial resolution allowed us to study individual thin anatomical structures of clinical relevance not visible by the standard model currently adopted in computational bioelectromagnetics. When we computed the electromagnetic field and specific absorption rate (SAR) at 7 Tesla MRI using this high-resolution model, we were able to obtain a detailed visualization of such fine anatomical structures as the epidermis/dermis, bone structures, bone-marrow, white matter and nasal and eye structures. PMID:18985401

  1. Quasi-static magnetic measurements to predict specific absorption rates in magnetic fluid hyperthermia experiments

    NASA Astrophysics Data System (ADS)

    Coral, D. F.; Mendoza Zélis, P.; de Sousa, M. E.; Muraca, D.; Lassalle, V.; Nicolás, P.; Ferreira, M. L.; Fernández van Raap, M. B.

    2014-01-01

    In this work, the issue on whether dynamic magnetic properties of polydispersed magnetic colloids modeled using physical magnitudes derived from quasi-static magnetic measurement can be extrapolated to analyze specific absorption rate data acquired at high amplitudes and frequencies of excitation fields is addressed. To this end, we have analyzed two colloids of magnetite nanoparticles coated with oleic acid and chitosan in water displaying, under a radiofrequency field, high and low specific heat power release. Both colloids are alike in terms of liquid carrier, surfactant and magnetic phase composition but differ on the nanoparticle structuring. The colloid displaying low specific dissipation consists of spaced magnetic nanoparticles of mean size around 4.8 nm inside a large chitosan particle of 52.5 nm. The one displaying high specific dissipation consists of clusters of magnetic nanoparticles of mean size around 9.7 nm inside a chitosan particle of 48.6 nm. The experimental evaluation of Néel and Brown relaxation times (˜10-10 s and 10-4 s, respectively) indicate that the nanoparticles in both colloids magnetically relax by Néel mechanism. The isothermal magnetization curves analysis for this mechanism show that the magnetic nanoparticles behave in the interacting superparamagnetic regime. The specific absorption rates were determined calorimetrically at 260 kHz and up to 52 kA/m and were well modeled within linear response theory using the anisotropy density energy retrieved from quasi-static magnetic measurement, validating their use to predict heating ability of a given polydispersed particle suspension. Our findings provide new insight in the validity of quasi-static magnetic characterization to analyze the high frequency behavior of polydispersed colloids within the framework of the linear response and Wohlfarth theories and indicate that dipolar interactions play a key role being their strength larger for the colloid displaying higher dissipation, i

  2. Impact of head morphology on local brain specific absorption rate from exposure to mobile phone radiation.

    PubMed

    Adibzadeh, Fatemeh; Bakker, Jurriaan F; Paulides, Margarethus M; Verhaart, René F; van Rhoon, Gerard C

    2015-01-01

    Among various possible health effects of mobile phone radiation, the risk of inducing cancer has the strongest interest of laymen and health organizations. Recently, the Interphone epidemiological study investigated the association between the estimated Radio Frequency (RF) dose from mobile phones and the risk of developing a brain tumor. Their dosimetric analysis included over 100 phone models but only two homogeneous head phantoms. So, the potential impact of individual morphological features on global and local RF absorption in the brain was not investigated. In this study, we performed detailed dosimetric simulations for 20 head models and quantified the variation of RF dose in different brain regions as a function of head morphology. Head models were exposed to RF fields from generic mobile phones at 835 and 1900 MHz in the "tilted" and "cheek" positions. To evaluate the local RF dose variation, we used and compared two different post-processing methods, that is, averaging specific absorption rate (SAR) over Talairach regions and over sixteen predefined 1 cm(3) cube-shaped field-sensors. The results show that the variation in the averaged SAR among the heads can reach up to 16.4 dB at a 1 cm(3) cube inside the brain (field-sensor method) and alternatively up to 15.8 dB in the medulla region (Talairach method). In conclusion, we show head morphology as an important uncertainty source for dosimetric studies of mobile phones. Therefore, any dosimetric analysis dealing with RF dose at a specific region in the brain (e.g., tumor risk analysis) should be based upon real morphology.

  3. Assessment of specific energy absorption rate (SAR) in the head from a TETRA handset

    NASA Astrophysics Data System (ADS)

    Dimbylow, Peter; Khalid, Mohammed; Mann, Simon

    2003-12-01

    Finite-difference time-domain (FDTD) calculations of the specific energy absorption rate (SAR) from a representative TETRA handset have been performed in an anatomically realistic model of the head. TETRA (Terrestrial Trunked Radio) is a modern digital private mobile radio system designed to meet the requirements of professional users, such as the police and fire brigade. The current frequency allocations in the UK are 380-385 MHz and 390-395 MHz for the public sector network. A comprehensive set of calculations of SAR in the head was performed for positions of the handset in front of the face and at both sides of the head. The representative TETRA handset considered, operating at 1 W in normal use, will show compliance with both the ICNIRP occupational and public exposure restrictions. The handset with a monopole antenna operating at 3 W in normal use will show compliance with both the ICNIRP occupational and public exposure restrictions. The handset with a helical antenna operating at 3 W in normal use will show compliance with the ICNIRP occupational exposure restriction but will be over the public exposure restriction by up to ~50% if kept in the position of maximum SAR for 6 min continuously.

  4. Assessment of specific energy absorption rate (SAR) in the head from a TETRA handset.

    PubMed

    Dimbylow, Peter; Khalid, Mohammed; Mann, Simon

    2003-12-01

    Finite-difference time-domain (FDTD) calculations of the specific energy absorption rate (SAR) from a representative TETRA handset have been performed in an anatomically realistic model of the head. TETRA (Terrestrial Trunked Radio) is a modern digital private mobile radio system designed to meet the requirements of professional users, such as the police and fire brigade. The current frequency allocations in the UK are 380-385 MHz and 390-395 MHz for the public sector network. A comprehensive set of calculations of SAR in the head was performed for positions of the handset in front of the face and at both sides of the head. The representative TETRA handset considered. operating at 1 W in normal use, will show compliance with both the ICNIRP occupational and public exposure restrictions. The handset with a monopole antenna operating at 3 W in normal use will show compliance with both the ICNIRP occupational and public exposure restrictions. The handset with a helical antenna operating at 3 W in normal use will show compliance with the ICNIRP occupational exposure restriction but will be over the public exposure restriction by up to approximately 50% if kept in the position of maximum SAR for 6 min continuously.

  5. A Prototype RF Dosimeter for Independent Measurement of the Average Specific Absorption Rate (SAR) During MRI

    PubMed Central

    Stralka, John P; Bottomley, Paul A

    2008-01-01

    Purpose To develop a scanner-independent dosimeter for measuring the average radio frequency (RF) power deposition and specific absorption rates (SAR) for human MRI exposure. Materials and Methods A prototype dosimeter has a transducer with orthogonal conducting loops surrounding a small signal-generating MRI sample. The loops contain resistors whose values are adjusted to load the scanner’s MRI coils equivalent to an average head or body during MRI. The scanner adjusts its power output to normal levels during setup, using the MRI sample. Following calibration, the total power and average SAR deposited in the transducer are measured from the root-mean-square (rms) power induced in the transducer during MRI. Results A 1.5 Tesla head transducer was adjusted to elicit the same load as the average of nine adult volunteers. Once adjusted, the transducer loads other head coils the same as the head does. The dosimeter is calibrated at up to 20 W total deposited power and 4.5 W/kg SAR in the average head, with about 5% accuracy. Conclusion This dosimeter provides a simple portable means of measuring the power deposited in a body-equivalent sample load, independent of the scanner. Further work will develop SAR dosimetry for the torso and for higher fields. PMID:17969145

  6. Specific absorption rate in electrically coupled biological samples between metal plates.

    PubMed

    Joines, W T; Blackman, C F; Spiegel, R J

    1986-01-01

    The specific absorption rate (SAR) in a biological sample irradiated by electromagnetic fields between the metal plates of a transmission line can be altered significantly by the spacing of the metal plates and the distance between neighboring samples. The SAR in spherical biological samples is calculated for a number of neighboring sample arrangements and metal-plate spacings by using the method of images and induced dipole coupling. For a decrease in metal-plate spacing, the derived equations predict an increase in SAR within a sample and a decrease in SAR with a decrease in neighboring-sample spacing. The calculations are compared with measurements made with the aid of an array of 1-in radius metal hemispheres on the lower plate of two parallel plates (thus forming an image system). The hemisphere on which measurements are taken is insulated from the metal plate and is connected via a coaxial center conductor to an HP 3582A spectrum analyzer that measures the voltage and hence the electric field intensity at the hemisphere. Measurements made at a frequency where wavelength is large compared with sample size (48 Hz) are in good agreement with calculations. PMID:3741491

  7. On the reliable measurement of specific absorption rates and intrinsic loss parameters in magnetic hyperthermia materials

    NASA Astrophysics Data System (ADS)

    Wildeboer, R. R.; Southern, P.; Pankhurst, Q. A.

    2014-12-01

    In the clinical application of magnetic hyperthermia, the heat generated by magnetic nanoparticles in an alternating magnetic field is used as a cancer treatment. The heating ability of the particles is quantified by the specific absorption rate (SAR), an extrinsic parameter based on the clinical response characteristic of power delivered per unit mass, and by the intrinsic loss parameter (ILP), an intrinsic parameter based on the heating capacity of the material. Even though both the SAR and ILP are widely used as comparative design parameters, they are almost always measured in non-adiabatic systems that make accurate measurements difficult. We present here the results of a systematic review of measurement methods for both SAR and ILP, leading to recommendations for a standardised, simple and reliable method for measurements using non-adiabatic systems. In a representative survey of 50 retrieved datasets taken from published papers, the derived SAR or ILP was found to be more than 5% overestimated in 24% of cases and more than 5% underestimated in 52% of cases.

  8. Potential chlorofluorocarbon replacements: OH reaction rate constants between 250 and 315 K and infrared absorption spectra

    SciTech Connect

    Garland, N.L.; Medhurst, L.J.; Nelson, H.H.

    1993-12-20

    The authors measured the rate constant for reactions of the OH radical with several potential chlorofluorocarbon replacements over the temperature range 251-314 K using laser photolysis laser-induced fluorescence techniques. The compounds studied and Arrhenius parameters determined from fits to the measured rate constants are as follows: CHF{sub 2}OCHF{sub 2} (E 134), k(T) = (5.4 {+-} 3.5) x 10{sup {minus}13} cm{sup 3} s{sup {minus}1} exp [({minus}3.1 {+-} 0.4 kcal mol{sup {minus}1})/RT]; CF{sub 3}CH{sub 2}CF{sub 3} (FC 236fa), k(T) = (2.0 {+-} 1.0) x 10{sup {minus}14} cm{sup 3} s{sup {minus}1} exp [({minus}1.8 {+-} 0.3 kcal mol{sup {minus}1})/RT]; CF{sub 3}CHFCHF{sub 2} (FC 236ea), k(T) = (2.0 {+-} 0.9) x 10{sup {minus}13} cm{sup 3} s{sup {minus}1} exp [({minus}2.0 {+-} 0.3 kcal mol{sup {minus}1})/RT]; and CF{sub 3}CF{sub 2}CH{sub 2}F (FC 236cb), k(T) = (2.6 {+-} 1.6) x 10{sup {minus}13} cm{sup 3} s{sup {minus}1} exp [({minus}2.2 {+-} 0.4 kcal mol{sup {minus}1})/RT]. The measured activation energies (2-3 kcal mol{sup {minus}1}) are consistent with a mechanism of H atom abstraction. The tropospheric lifetimes, estimated from the measured OH reaction rates, and measured integrated infrared absorption cross sections over the range 770 to 1430 cm{sup {minus}1} suggest that E 134 and FC 236fa may have significant global warming potential, while FC 236ea and FC 236cb do not. 17 refs., 4 figs., 3 tabs.

  9. Quantifying intra- and extracellular aggregation of iron oxide nanoparticles and its influence on specific absorption rate.

    PubMed

    Jeon, Seongho; Hurley, Katie R; Bischof, John C; Haynes, Christy L; Hogan, Christopher J

    2016-09-21

    A promising route to cancer treatment is hyperthermia, facilitated by superparamagnetic iron oxide nanoparticles (SPIONs). After exposure to an alternating external magnetic field, SPIONs generate heat, quantified by their specific absorption rate (SAR, in W g(-1) Fe). However, without surface functionalization, commercially available, high SAR SPIONs (EMG 308, Ferrotec, USA) aggregate in aqueous suspensions; this has been shown to reduce SAR. Further reduction in SAR has been observed for SPIONs in suspensions containing cells, but the origin of this further reduction has not been made clear. Here, we use image analysis methods to quantify the structures of SPION aggregates in the extra- and intracellular milieu of LNCaP cell suspensions. We couple image characterization with nanoparticle tracking analysis and SAR measurements of SPION aggregates in cell-free suspensions, to better quantify the influence of cellular uptake on SPION aggregates and ultimately its influence on SAR. We find that in both the intra- and extracellular milieu, SPION aggregates are well-described by a quasifractal model, with most aggregates having fractal dimensions in the 1.6-2.2 range. Intracellular aggregates are found to be significantly larger than extracellular aggregates and are commonly composed of more than 10(3) primary SPION particles (hence they are "superaggregates"). By using high salt concentrations to generate such superaggregates and measuring the SAR of suspensions, we confirm that it is the formation of superaggregates in the intracellular milieu that negatively impacts SAR, reducing it from above 200 W g(-1) Fe for aggregates composed of fewer than 50 primary particles to below 50 W g(-1) for superaggregates. While the underlying physical mechanism by which aggregation leads to reduction in SAR remains to be determined, the methods developed in this study provide insight into how cellular uptake influences the extent of SPION aggregation, and enable estimation of the

  10. Survey on Different Samsung with Nokia Smart Mobile Phones in the Specific Absorption Rate Electrical Field of Head

    PubMed Central

    Fakhri, Yadolah; Alinejad, Azim; Keramati, Hassan; Bay, Abotaleb; Avazpour, Moayed; Zandsalimi, Yahya; Moradi, Bigard; Amirhajeloo, Leila Rasouli; Mirzaei, Maryam

    2016-01-01

    The use of smart phones is increasing in the world. This excessive use, especially in the last two decades, has created too much concern on the effects of emitted electromagnetic fields and specific absorption rate on human health. In this descriptive-analytical study of the electric field resulting from smart phones of Samsung and Nokia by portable measuring device, electromagnetic field, Model HI-3603-VDT/VLF, were measured. Then, head absorption rate was calculated in these two mobiles by ICNIRP equation. Finally, the comparison of specific absorption rate, especially between Samsung and Nokia smart phones, was conducted by T-Test statistics analysis. The mean of electric field for Samsung and Nokia smart mobile phones was obtained 1.8 ±0.19 v/m and 2.23±0.39 v/m, respectively, while the range of the electric field was obtained as 1.56-2.21 v/m and 1.69-2.89 v/m for them, respectively. The mean of specific absorption rate in Samsung and Nokia was obtained 0.002 ± 0.0005 W/Kg and 0.0041±0.0013 W/Kg at the frequency of 900 MHz and 0.004±0.001 W/Kg and 0.0062±0.0002 W/Kg at the frequency of 1800 MHz respectively. The ratio of mean electronic field to guidance in the Samsung mobile phone at the frequency of 900 MHz and 1800 MHz was 4.36% and 3.34%, while was 5.62% and 4.31% in the Nokia mobile phone, respectively. The ratio of mean head specific absorption rate in smart mobile phones of Samsung and Nokia in the guidance level at the frequency of 900 was 0.15% and 0.25%, respectively, while was 0.23% and 0.38% at the frequency of 1800 MHz, respectively. The rate of specific absorption of Nokia smart mobile phones at the frequencies of 900 and 1800 MHz was significantly higher than Samsung (p value <0.05). Hence, we can say that in a fixed period, health risks of Nokia smart phones is higher than Samsung smart mobile phone.

  11. Survey on Different Samsung with Nokia Smart Mobile Phones in the Specific Absorption Rate Electrical Field of Head.

    PubMed

    Fakhri, Yadolah; Alinejad, Azim; Keramati, Hassan; Bay, Abotaleb; Avazpour, Moayed; Zandsalimi, Yahya; Moradi, Bigard; Rasouli Amirhajeloo, Leila; Mirzaei, Maryam

    2016-01-01

    The use of smart phones is increasing in the world. This excessive use, especially in the last two decades, has created too much concern on the effects of emitted electromagnetic fields and specific absorption rate on human health. In this descriptive-analytical study of the electric field resulting from smart phones of Samsung and Nokia by portable measuring device, electromagnetic field, Model HI-3603-VDT/VLF, were measured. Then, head absorption rate was calculated in these two mobiles by ICNIRP equation. Finally, the comparison of specific absorption rate, especially between Samsung and Nokia smart phones, was conducted by T-Test statistics analysis. The mean of electric field for Samsung and Nokia smart mobile phones was obtained 1.8 ±0.19 v/m  and 2.23±0.39 v/m , respectively, while the range of the electric field was obtained as 1.56-2.21 v/m and 1.69-2.89 v/m for them, respectively. The mean of specific absorption rate in Samsung and Nokia was obtained 0.002 ± 0.0005 W/Kg and 0.0041±0.0013 W/Kg at the frequency of 900 MHz and 0.004±0.001 W/Kg and 0.0062±0.0002 W/Kg at the frequency of 1800 MHz respectively. The ratio of mean electronic field to guidance in the Samsung mobile phone at the frequency of 900 MHz and 1800 MHz was 4.36% and 3.34%, while was 5.62% and 4.31% in the Nokia mobile phone, respectively. The ratio of mean head specific absorption rate in smart mobile phones of Samsung and Nokia in the guidance level at the frequency of 900 was 0.15% and 0.25%, respectively, while was 0.23 %and 0.38% at the frequency of 1800 MHz, respectively. The rate of specific absorption of Nokia smart  mobile phones at the frequencies of 900 and 1800 MHz  was significantly higher than Samsung (p value <0.05). Hence, we can say that in a fixed period, health risks of Nokia smart phones is higher than Samsung smart mobile phone.

  12. Survey on Different Samsung with Nokia Smart Mobile Phones in the Specific Absorption Rate Electrical Field of Head.

    PubMed

    Fakhri, Yadolah; Alinejad, Azim; Keramati, Hassan; Bay, Abotaleb; Avazpour, Moayed; Zandsalimi, Yahya; Moradi, Bigard; Rasouli Amirhajeloo, Leila; Mirzaei, Maryam

    2016-01-01

    The use of smart phones is increasing in the world. This excessive use, especially in the last two decades, has created too much concern on the effects of emitted electromagnetic fields and specific absorption rate on human health. In this descriptive-analytical study of the electric field resulting from smart phones of Samsung and Nokia by portable measuring device, electromagnetic field, Model HI-3603-VDT/VLF, were measured. Then, head absorption rate was calculated in these two mobiles by ICNIRP equation. Finally, the comparison of specific absorption rate, especially between Samsung and Nokia smart phones, was conducted by T-Test statistics analysis. The mean of electric field for Samsung and Nokia smart mobile phones was obtained 1.8 ±0.19 v/m  and 2.23±0.39 v/m , respectively, while the range of the electric field was obtained as 1.56-2.21 v/m and 1.69-2.89 v/m for them, respectively. The mean of specific absorption rate in Samsung and Nokia was obtained 0.002 ± 0.0005 W/Kg and 0.0041±0.0013 W/Kg at the frequency of 900 MHz and 0.004±0.001 W/Kg and 0.0062±0.0002 W/Kg at the frequency of 1800 MHz respectively. The ratio of mean electronic field to guidance in the Samsung mobile phone at the frequency of 900 MHz and 1800 MHz was 4.36% and 3.34%, while was 5.62% and 4.31% in the Nokia mobile phone, respectively. The ratio of mean head specific absorption rate in smart mobile phones of Samsung and Nokia in the guidance level at the frequency of 900 was 0.15% and 0.25%, respectively, while was 0.23 %and 0.38% at the frequency of 1800 MHz, respectively. The rate of specific absorption of Nokia smart  mobile phones at the frequencies of 900 and 1800 MHz  was significantly higher than Samsung (p value <0.05). Hence, we can say that in a fixed period, health risks of Nokia smart phones is higher than Samsung smart mobile phone. PMID:27157169

  13. Heating from free-free absorption and the mass-loss rate of the progenitor stars to supernovae

    SciTech Connect

    Björnsson, C.-I.; Lundqvist, P. E-mail: peter@astro.su.se

    2014-06-01

    An accurate determination of the mass-loss rate of the progenitor stars to core-collapse supernovae is often limited by uncertainties pertaining to various model assumptions. It is shown that under conditions when the temperature of the circumstellar medium is set by heating due to free-free absorption, observations of the accompanying free-free optical depth allow a direct determination of the mass-loss rate from observed quantities in a rather model-independent way. The temperature is determined self-consistently, which results in a characteristic time dependence of the free-free optical depth. This can be used to distinguish free-free heating from other heating mechanisms. Since the importance of free-free heating is quite model dependent, this also makes possible several consistency checks of the deduced mass-loss rate. It is argued that the free-free absorption observed in SN 1993J is consistent with heating from free-free absorption. The deduced mass-loss rate of the progenitor star is, approximately, 10{sup –5} M {sub ☉} yr{sup –1} for a wind velocity of 10 km s{sup –1}.

  14. Calculations of Solar Shortwave Heating Rates due to Black Carbon and Ozone Absorption Using in Situ Measurements

    NASA Technical Reports Server (NTRS)

    Gao, R. S.; Hall, S. R.; Swartz, W. H.; Spackman, J. R.; Watts, L. A.; Fahey, D. W.; Aikin, K. C.; Shetter, R. E.; Bui, T. P.

    2008-01-01

    Results for the solar heating rates in ambient air due to absorption by black-carbon (BC) containing particles and ozone are presented as calculated from airborne observations made in the tropical tropopause layer (TTL) in January-February 2006. The method uses airborne in situ observations of BC particles, ozone and actinic flux. Total BC mass is obtained along the flight track by summing the masses of individually detected BC particles in the range 90 to 600-nm volume-equivalent diameter, which includes most of the BC mass. Ozone mixing ratios and upwelling and partial downwelling solar actinic fluxes were measured concurrently with BC mass. Two estimates used for the BC wavelength-dependent absorption cross section yielded similar heating rates. For mean altitudes of 16.5, 17.5, and 18.5 km (0.5 km) in the tropics, average BC heating rates were near 0.0002 K/d. Observed BC coatings on individual particles approximately double derived BC heating rates. Ozone heating rates exceeded BC heating rates by approximately a factor of 100 on average and at least a factor of 4, suggesting that BC heating rates in this region are negligible in comparison.

  15. Operation of a low temperature absorption chiller at rating point and at reduced evaporator temperature

    NASA Astrophysics Data System (ADS)

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

    1985-01-01

    The returned fifteen ton Solar Absorption Machine (SAM) 015 chiller was given a cursory visual inspection, some obvious problems were remedied, and then it was placed on a test stand to get a measure of dirty performance. It was then given a standard acid clean, the water side of the tubes was brushed clean, and then the machine was retested. The before and after cleaning data were compared to equivalent data taken before the machine was shipped. The second part of the work statement was to experimentally demonstrate the technical feasibility of operating the chiller at evaporator temperatures below 0(0)C (32(0)F) and identify any operational problems.

  16. Modifying the high rate algal pond light environment and its effects on light absorption and photosynthesis.

    PubMed

    Sutherland, Donna L; Montemezzani, Valerio; Howard-Williams, Clive; Turnbull, Matthew H; Broady, Paul A; Craggs, Rupert J

    2015-03-01

    The combined use of high rate algal ponds (HRAPs) for wastewater treatment and commercial algal production is considered to be an economically viable option. However, microalgal photosynthesis and biomass productivity is constrained in HRAPs due to light limitation. This paper investigates how the light climate in the HRAP can be modified through changes in pond depth, hydraulic retention time (HRT) and light/dark turnover rate and how this impacts light absorption and utilisation by the microalgae. Wastewater treatment HRAPs were operated at three different pond depth and HRT during autumn. Light absorption by the microalgae was most affected by HRT, significantly decreasing with increasing HRT, due to increased internal self-shading. Photosynthetic performance (as defined by Pmax, Ek and α), significantly increased with increasing pond depth and decreasing HRT. Despite this, increasing pond depth and/or HRT, resulted in decreased pond light climate and overall integrated water column net oxygen production. However, increased light/dark turnover was able to compensate for this decrease, bringing the net oxygen production in line with shallower ponds operated at shorter HRT. On overcast days, modelled daily net photosynthesis significantly increased with increased light/dark turnover, however, on clear days such increased turnover did not enhance photosynthesis. This study has showed that light absorption and photosynthetic performance of wastewater microalgae can be modified through changes to pond depth, HRT and light/dark turnover.

  17. A simplified method for calculating the atmospheric heating rate by absorption of solar radiation in the stratosphere and mesosphere

    NASA Technical Reports Server (NTRS)

    Shimazaki, T.; Helmle, L. C.

    1979-01-01

    Calculations of the atmospheric heating rate by absorption of solar radiation by O3, H2O, and CO2 are reported. The method needs only seven parameters for each molecule and is particularly useful for heating calculations in three-dimensional global circulation models below 80 km. Applying the formula to the observed distributions of O3, H2O, and CO2 produces reasonable latitudinal and seasonal variations in the heating rate. The calculated heating rate, however, is sensitive to the global distributions of the absorbing gases, and uncertainties in the O3 distribution above approximately 50 km and the H2O distribution below approximately 20 km may seriously affect the global distributions of the heating rate in these regions.

  18. FDTD chiral brain tissue model for specific absorption rate determination under radiation from mobile phones at 900 and 1800 MHz

    NASA Astrophysics Data System (ADS)

    Zamorano, M.; Torres-Silva, H.

    2006-04-01

    A new electrodynamics model formed by chiral bioplasma, which represents the human head inner structure and makes it possible to analyse its behaviour when it is irradiated by a microwave electromagnetic field from cellular phones, is presented. The finite-difference time-domain (FDTD) numeric technique is used, which allows simulation of the electromagnetic fields, deduced with Maxwell's equations, and allows us to simulate the specific absorption rate (SAR). The results show the SAR behaviour as a function of the input power and the chirality factor. In considering the chiral brain tissue in the proposed human head model, the two more important conclusions of our work are the following: (a) the absorption of the electromagnetic fields from cellular phones is stronger, so the SAR coefficient is higher than that using the classical model, when values of the chiral factor are of order of 1; (b) 'inverse skin effect' shows up at 1800 MHz, with respect to a 900 MHz source.

  19. Variable food absorption by Antarctic krill: Relationships between diet, egestion rate and the composition and sinking rates of their fecal pellets

    NASA Astrophysics Data System (ADS)

    Atkinson, A.; Schmidt, K.; Fielding, S.; Kawaguchi, S.; Geissler, P. A.

    2012-01-01

    The kinetics of food processing by zooplankton affects both their energy budgets and the biogeochemical fate of their fecal pellets. We sampled 40 schools of krill across the Scotia Sea during spring, summer and autumn and found that in all 3 seasons, every aspect of their absorption and defecation varied greatly. The C content of fecal pellets varied from 0.85% to 29% of their dry mass (median 9.8%) and C egestion rates varied 75-fold. C:N mass ratios of pellets ranged from 4.9 to 13.2 (median 7.8), higher than values of 3.9 in the krill and 5.4 in their food, pointing to enhanced uptake of N. Pellet sinking rates equated to 27-1218 m d -1 (median 304 m d -1), being governed mainly by pellet diameter (80-600 μm, mean 183 μm) and density (1.038-1.391 g cm -3, mean 1.121 g cm -3). Pellets showed little loss of C or N in filtered seawater over the first 2 days and were physically robust. When feeding rates were low, slow gut passage time and high absorption efficiency resulted in low egestion rates of pellets that were low in C and N content. These pellets were compact, dense and fast-sinking. Conversely, in good feeding conditions much food tended to pass quickly through the gut and was not efficiently absorbed, producing C and N-rich, slow-sinking pellets. Such "superfluous feeding" probably maximises the absolute rates of nutrient absorption. Food composition was also important: diatom-rich diets depressed the C content of the pellets but increased their sinking rates, likely due to silica ballasting. So depending on how krill process food, their pellets could represent both vehicles for rapid export and slow sinking, C and N-rich food sources for pelagic scavengers. C egestion rates by krill averaged 3.4% of summer primary production (and ingestion rates would be 2-10-fold higher than this) so whatever the fate of the pellets, krill are an important re-packager within the food web. While salp pellets tend to sink faster than those of krill, it is the latter

  20. New model for assessing dose, dose rate, and temperature sensitivity of radiation-induced absorption in glasses

    SciTech Connect

    Gilard, Olivier; Quadri, Gianandrea; Caussanel, Matthieu; Duval, Herve; Reynaud, Francois

    2010-11-15

    A new theoretical approach is proposed to explain the dose, dose rate and temperature sensitivity of the radiation-induced absorption (RIA) in glasses. In this paper, a {beta}{sup th}-order dispersive kinetic model is used to simulate the growth of the density of color centers in irradiated glasses. This model yields an explanation for the power-law dependence on dose and dose rate usually observed for the RIA in optical fibers. It also leads to an Arrhenius-like relationship between the RIA and the glass temperature during irradiation. With a very limited number of adjustable parameters, the model succeeds in explaining, with a good agreement, the RIA growth of two different optical fiber references over wide ranges of dose, dose rate and temperature.

  1. A physico-chemical properties based model for estimating evaporation and absorption rates of perfumes from skin.

    PubMed

    Kasting, G B; Saiyasombati, P

    2001-02-01

    Because of their potential for inducing allergic contact dermatitis (ACD) if used improperly, perfumes are carefully assessed for dermal safety prior to incorporation into cosmetic products. Exposure assessment for these materials often involves the conservative assumption of 100% absorption of each component. This report describes an improved method to estimate the absorption and evaporation of perfume ingredients from skin, based on their physico-chemical properties. The effect of environmental variables such as temperature and wind velocity can be accounted for in a logical way. This was accomplished using a first-order kinetic approach expected to be applicable for small doses applied to skin. Skin penetration rate was calculated as a fraction of the maximum flux estimated from the compound's lipid solubility, S(lip) (represented by the product of octanol/water partition coefficient, K(octt), and water solubility, S(w)), and molecular weight, MW. Evaporation rates were estimated from a modified Henry's Law approach with a stagnant boundary layer whose thickness is a function of surface airflow, v. At a given value of v, evaporation rate was assumed proportional to the ratio P(vp)/S(lip), where P(vp) is the vapour pressure of the ingredient at skin temperature, T. The model predicts a relationship for total evaporation from skin of the form %evap = 100x/(k+x) where x = P(vp)MW(2.7)/(K(oct)S(w)) and k is a parameter which depends only on v and T. Comparison with published data on perfume evaporation from human skin in vivo showed good agreement between theory and experiment for two closely related perfume mixtures (r(2) = 0.52-0.74, s = 12-14%, n = 10). Thus, the method would seem to have a good prospect of providing skin absorption estimates suitable for use in exposure assessment and improved understanding of dose-related contact allergy.

  2. A study on transmission characteristics and specific absorption rate using impedance-matched electrodes for various human body communication.

    PubMed

    Machida, Yuta; Yamamoto, Takahiko; Koshiji, Kohji

    2013-01-01

    Human body communication (HBC) is a new communication technology that has presented potential applications in health care and elderly support systems in recent years. In this study, which is focused on a wearable transmitter and receiver for HBC in a body area network (BAN), we performed electromagnetic field analysis and simulation using the finite difference time domain (FDTD) method with various models of the human body. Further we redesigned a number of impedance-matched electrodes to allow transmission without stubs or transformers. The specific absorption rate (SAR) and transmission characteristics S21 of these electrode structures were compared for several models.

  3. Absorbed dose rates in tissue from prompt gamma emissions from near-thermal neutron absorption

    DOE PAGES

    Schwahn, Scott O.

    2015-10-01

    Prompt gamma emission data from the International Atomic Energy Agency s Prompt Gamma-ray Neutron Activation Analysis database are analyzed to determine the absorbed dose rates in tissue to be expected when natural elements are exposed in a near-thermal neutron environment.

  4. High Repetition Rate and Frequency Stabilized Ho:YLF Laser for CO2 Differential Absorption Lidar

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Petros, M.; Petzar, Pau; Trieu, Bo; Lee, Hyung; Singh, U.

    2009-01-01

    High repetition rate operation of an injection seeded Ho:YLF laser has been demonstrated. For 1 kHz operation, the output pulse energy reaches 5.8mJ and the optical-to-optical efficiency is 39% when the pump power is 14.5W.

  5. Enhancement of specific absorption rate by exchange coupling of the core-shell structure of magnetic nanoparticles for magnetic hyperthermia

    NASA Astrophysics Data System (ADS)

    Phadatare, M. R.; Meshram, J. V.; Gurav, K. V.; Hyeok Kim, Jin; Pawar, S. H.

    2016-03-01

    Conversion of electromagnetic energy into heat by nanoparticles (NPs) has the potential to be a powerful, non-invasive technique for biomedical applications such as magnetic fluid hyperthermia, drug release, disease treatment and remote control of single cell functions, but poor conversion efficiencies have hindered practical applications so far. In this paper, an attempt has been made to increase the efficiency of magnetic thermal induction by NPs. To increase the efficiency of magnetic thermal induction by NPs, one can take advantage of the exchange coupling between a magnetically hard core and magnetically soft shell to tune the magnetic properties of the NP and maximize the specific absorption rate, which is the gauge of conversion efficiency. In order to examine the tunability of magnetocrystalline anisotropy and its magnetic heating power, a representative magnetically hard material (CoFe2O4) has been coupled to a soft material (Ni0.5Zn0.5Fe2O4). The synthesized NPs show specific absorption rates that are of an order of magnitude larger than the conventional one.

  6. Heating rates in furnace atomic absorption using the L'vov platform

    USGS Publications Warehouse

    Koirtyohann, S.R.; Giddings, R.C.; Taylor, H.E.

    1984-01-01

    Heating rate profiles for the furnace tube wall, the furnace atmosphere, and a L'vov platform were established for a range of conditions in a cyclically heated graphite atomizer. The tube wall profile was made by direct observation with a recording optical pyrometer. The sodium line reversal method was used to establish the heating rate of the furnace atmosphere, and appearance temperatures for a series metals of differing volatility was used to establish platform profiles. The tube wall heating rate was nearly linear at 2240??C s- until the desired temperature was reached after which the temperature remained constant. The furnace atmosphere reached a given temperature 0.2-0.4 s later than the tube wall through most of the atomize cycle. The platform lagged the tube wall 0.5-0.8 s. Under typical operating conditions the furnace atmosphere was 100-200??C cooler than the tube wall and at nearly constant temperature when the analyte vaporized from the platform. The L'vov platform causes the cyclically heated commercial furnace to approximate the behavior of a constant temperature furnace during atomization. ?? 1984.

  7. Unimolecular Decomposition Rate of the Criegee Intermediate (CH3)2COO Measured Directly with UV Absorption Spectroscopy.

    PubMed

    Smith, Mica C; Chao, Wen; Takahashi, Kaito; Boering, Kristie A; Lin, Jim Jr-Min

    2016-07-14

    The unimolecular decomposition of (CH3)2COO and (CD3)2COO was measured by direct detection of the Criegee intermediate at temperatures from 283 to 323 K using time-resolved UV absorption spectroscopy. The unimolecular rate coefficient kd for (CH3)2COO shows a strong temperature dependence, increasing from 269 ± 82 s(-1) at 283 K to 916 ± 56 s(-1) at 323 K with an Arrhenius activation energy of ∼6 kcal mol(-1). The bimolecular rate coefficient for the reaction of (CH3)2COO with SO2, kSO2, was also determined in the temperature range 283 to 303 K. Our temperature-dependent values for kd and kSO2 are consistent with previously reported relative rate coefficients kd/kSO2 of (CH3)2COO formed from ozonolysis of tetramethyl ethylene. Quantum chemical calculations of kd for (CH3)2COO are consistent with the experiment, and the combination of experiment and theory for (CD3)2COO indicates that tunneling plays a significant role in (CH3)2COO unimolecular decomposition. The fast rates of unimolecular decomposition for (CH3)2COO measured here, in light of the relatively slow rate for the reaction of (CH3)2COO with water previously reported, suggest that thermal decomposition may compete with the reactions with water and with SO2 for atmospheric removal of the dimethyl-substituted Criegee intermediate.

  8. Aqueous suspensions of polymer coated magnetite nanoparticles: Colloidal stability, specific absorption rate, and transverse relaxivity

    NASA Astrophysics Data System (ADS)

    Saville, Steven Lee

    The design, functionalization, characterization, and applications of magnetic nanoparticles have garnered significant interest over the past several decades. While this area has garnered increasing attention, several questions remain unanswered about the stability of these systems and it's influence on their biomedical applications. To help answer these questions about the stability of these, a novel tri(nitroDOPA) terminated polymer based ligand has been developed for the stabilization of magnetite nanoparticles. The synthesis involves a process in which ethylene oxide is polymerized using a trivinyl initiator, modified with carboxylic acid using a free radical addition of mercaptoundecanoic acid, and then functionalized with nitroDOPA using N,N-dicyclohexylcarbodiimide (DCC) and N-hydroxysuccinimide (NHS) chemistry. This polymer has displayed robust adhesion even in harsh chemical environments, out performing many polymers used today for the stabilization of magnetite. Along these same lines, the effects of instability of these systems were analyzed in both MRI and magnetic hyperthermia applications. It is widely known that formation of linear aggregates (i.e. chains) occurs in more concentrated ferrofluids systems and that this has an affect on the ferrofluid properties. It has been recently reported that for some suspensions of magnetic nanoparticles the transverse proton relaxation rate, R2, is dependent on the time that the sample is exposed to an applied magnetic field. This time dependence has been linked to the formation of linear aggregates or chains in an applied magnetic field via numerical modeling. In this work the relationships between colloidal stability, the formation of these linear structures, and changes observed in the proton transverse relaxation rate and heating rate in magnetic hyperthermia of aqueous suspensions of magnetic particles are examined. The results indicate that varying the ligand length has a direct effect on the colloidal

  9. HCFC-133a (CF3CH2Cl): OH rate coefficient, UV and infrared absorption spectra, and atmospheric implications

    NASA Astrophysics Data System (ADS)

    McGillen, Max R.; Bernard, François; Fleming, Eric L.; Burkholder, James B.

    2015-07-01

    HCFC-133a (CF3CH2Cl), an ozone-depleting substance, is primarily removed from the atmosphere by gas-phase reaction with OH radicals and by UV photolysis. The rate coefficient, k, for the OH + HCFC-133a reaction was measured between 233 and 379 K and is given by k(T) = (9.32 ± 0.8) × 10-13 exp(-(1296 ± 28)/T), where k(296 K) was measured to be (1.10 ± 0.02) × 10-14 (cm3 molecule-1 s-1) (2σ precision uncertainty). The HCFC-133a UV absorption spectrum was measured between 184.95 and 240 nm at 213-323 K, and a spectrum parameterization is presented. The HCFC-133a atmospheric loss processes, lifetime, ozone depletion potential, and uncertainties were evaluated using a 2-D atmospheric model. The global annually averaged steady state lifetime and ozone depletion potential (ODP) were determined to be 4.45 (4.04-4.90) years and 0.017 (±0.001), respectively, where the ranges are based solely on the 2σ uncertainty in the kinetic and photochemical parameters. The infrared absorption spectrum of HCFC-133a was measured, and its global warming potential was determined to be 380 on the 100 year time horizon.

  10. Comparison of specific absorption rate induced in brain tissues of a child and an adult using mobile phone

    NASA Astrophysics Data System (ADS)

    Lu, Mai; Ueno, Shoogo

    2012-04-01

    The steady increase of mobile phone usage, especially mobile phones by children, has led to a rising concern about the possible adverse health effects of radio frequency electromagnetic field exposure. The objective of this work is to study whether there is a larger radio frequency energy absorption in the brain of a child compared to that of an adult. For this reason, three high-resolution models, two child head models (6 - and 11-year old) and one adult head model (34-year old) have been used in the study. A finite-difference time-domain method was employed to calculate the specific absorption rate (SAR) in the models from exposure to a generic handset at 1750 MHz. The results show that the SAR distributions in the human brain are age-dependent, and there is a deeper penetration of the absorbed SAR in the child's brain. The induced SAR can be significantly higher in subregions of the child's brain. In all of the examined cases, the SAR values in the brains of a child and an adult are well below the IEEE safety standard.

  11. Development of a carbonate absorption-based process for post-combustion CO2 capture: The role of biocatalyst to promote CO2 absorption rate

    USGS Publications Warehouse

    Lu, Y.; Ye, X.; Zhang, Z.; Khodayari, A.; Djukadi, T.

    2011-01-01

    An Integrated Vacuum Carbonate Absorption Process (IVCAP) for post-combustion carbon dioxide (CO2) capture is described. IVCAP employs potassium carbonate (PC) as a solvent, uses waste or low quality steam from the power plant for CO2 stripping, and employs a biocatalyst, carbonic anhydrase (CA) enzyme, for promoting the CO2 absorption into PC solution. A series of experiments were performed to evaluate the activity of CA enzyme mixed in PC solutions in a stirred tank reactor system under various temperatures, CA dosages, CO2 loadings, CO2 partial pressures, and the presence of major flue gas contaminants. It was demonstrated that CA enzyme is an effective biocatalyst for CO2 absorption under IVCAP conditions. ?? 2011 Published by Elsevier Ltd.

  12. Ingestion of insoluble dietary fibre increased zinc and iron absorption and restored growth rate and zinc absorption suppressed by dietary phytate in rats.

    PubMed

    Hayashi, K; Hara, H; Asvarujanon, P; Aoyama, Y; Luangpituksa, P

    2001-10-01

    We examined the effects of ingestion of five types of insoluble fibre on growth and Zn absorption in rats fed a marginally Zn-deficient diet (6.75 mg (0.103 mmol) Zn/kg diet) with or without added sodium phytate (12.6 mmol/kg diet). The types of insoluble fibre tested were corn husks, watermelon skin, yam-bean root (Pachyrhizus erosus) and pineapple core, and cellulose was used as a control (100 g/kg diet). Body-weight gain in the cellulose groups was suppressed by 57 % by feeding phytate. Body-weight gain in phytate-fed rats was 80 % greater in the watermelon skin fibre and yam-bean root fibre group than that in the cellulose group. Zn absorption ratio in the cellulose groups was lowered by 46 and 70 % in the first (days 7-10) and second (days 16-19) measurement periods with feeding phytate. In the rats fed the phytate-containing diets, Zn absorption ratio in the watermelon skin, yam-bean root and pineapple core fibre groups was 140, 80 and 54 % higher respectively than that in the cellulose group, in the second period. Fe absorption was not suppressed by phytate, however, feeding of these three types of fibre promoted Fe absorption in rats fed phytate-free diets. The concentration of soluble Zn in the caecal contents in the watermelon skin fibre or yam-bean root fibre groups was identical to that in the control group in spite of a higher short-chain fatty acid concentration and lower pH in the caecum. These findings indicate that ingestion of these types of insoluble fibre recovered the growth and Zn absorption suppressed by feeding a high level of phytate, and factors other than caecal fermentation may also be involved in this effect of insoluble fibre. PMID:11591231

  13. Experimental determination of whole body average specific absorption rate (SAR) of mice exposed to 200-400 MHz CW

    SciTech Connect

    Marshall, S.V.; Brown, R.F.

    1983-01-01

    A maximum of six live mice, mouse cadavers, prolate spheroids molded from muscle-equivalent tissue, or saline-filled culture flasks, were exposed to continuous wave radiation in a TEM cell at frequencies between 200 and 400 MHz. Whole-body average specific absorption rate (SAR) was determined from power meter measurements of incident, reflected, and transmitted powers. The SARs for both live mice and cadavers were approximately twice that for the prolate spheroid models, and when housed in Plexiglas restraining cages, about 2 1/2 times greater. An error multiplying factor is identified, that quantitatively expresses how SAR data obtained by the three-power-meter method becomes progressively more noisy as the irradiation frequency is lowered or as the TEM cell cross section is increased.

  14. Hydrogen capacity and absorption rate of the SAES St707 non-evaporable getter at various temperatures.

    SciTech Connect

    Hsu, Irving; Mills, Bernice E.

    2010-08-01

    A prototype of a tritium thermoelectric generator (TTG) is currently being developed at Sandia. In the TTG, a vacuum jacket reduces the amount of heat lost from the high temperature source via convection. However, outgassing presents challenges to maintaining a vacuum for many years. Getters are chemically active substances that scavenge residual gases in a vacuum system. In order to maintain the vacuum jacket at approximately 1.0 x 10{sup -4} torr for decades, nonevaporable getters that can operate from -55 C to 60 C are going to be used. This paper focuses on the hydrogen capacity and absorption rate of the St707{trademark} non-evaporable getter by SAES. Using a getter testing manifold, we have carried out experiments to test these characteristics of the getter over the temperature range of -77 C to 60 C. The results from this study can be used to size the getter appropriately.

  15. Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy

    PubMed Central

    Stigliano, Robert; Baker, Ian

    2015-01-01

    Magnetic nanoparticles (MNPs), referred to as the Dartmouth MNPs, which exhibit high specific absorption rate at low applied field strength have been developed for hyperthermia therapy applications. The MNPs consist of small (2–5 nm) single crystals of gamma-Fe2O3 with saccharide chains implanted in their crystalline structure, forming 20–40 nm flower-like aggregates with a hydrodynamic diameter of 110–120 nm. The MNPs form stable (>12 months) colloidal solutions in water and exhibit no hysteresis under an applied quasistatic magnetic field, and produce a significant amount of heat at field strengths as low as 100 Oe at 99–164 kHz. The MNP heating mechanisms under an alternating magnetic field (AMF) are discussed and analyzed quantitatively based on (a) the calculated multi-scale MNP interactions obtained using a three dimensional numerical model called the method of auxiliary sources, (b) measured MNP frequency spectra, and (c) quantified MNP friction losses based on magneto-viscous theory. The frequency responses and hysteresis curves of the Dartmouth MNPs are measured and compared to the modeled data. The specific absorption rate of the particles is measured at various AMF strengths and frequencies, and compared to commercially available MNPs. The comparisons demonstrate the superior heating properties of the Dartmouth MNPs at low field strengths (<250 Oe). This may extend MNP hyperthermia therapy to deeper tumors that were previously non-viable targets, potentially enabling the treatment of some of the most difficult cancers, such as pancreatic and rectal cancers, without damaging normal tissue. PMID:25825545

  16. Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy

    NASA Astrophysics Data System (ADS)

    Shubitidze, Fridon; Kekalo, Katsiaryna; Stigliano, Robert; Baker, Ian

    2015-03-01

    Magnetic nanoparticles (MNPs), referred to as the Dartmouth MNPs, which exhibit high specific absorption rate at low applied field strength have been developed for hyperthermia therapy applications. The MNPs consist of small (2-5 nm) single crystals of gamma-Fe2O3 with saccharide chains implanted in their crystalline structure, forming 20-40 nm flower-like aggregates with a hydrodynamic diameter of 110-120 nm. The MNPs form stable (>12 months) colloidal solutions in water and exhibit no hysteresis under an applied quasistatic magnetic field, and produce a significant amount of heat at field strengths as low as 100 Oe at 99-164 kHz. The MNP heating mechanisms under an alternating magnetic field (AMF) are discussed and analyzed quantitatively based on (a) the calculated multi-scale MNP interactions obtained using a three dimensional numerical model called the method of auxiliary sources, (b) measured MNP frequency spectra, and (c) quantified MNP friction losses based on magneto-viscous theory. The frequency responses and hysteresis curves of the Dartmouth MNPs are measured and compared to the modeled data. The specific absorption rate of the particles is measured at various AMF strengths and frequencies, and compared to commercially available MNPs. The comparisons demonstrate the superior heating properties of the Dartmouth MNPs at low field strengths (<250 Oe). This may extend MNP hyperthermia therapy to deeper tumors that were previously non-viable targets, potentially enabling the treatment of some of the most difficult cancers, such as pancreatic and rectal cancers, without damaging normal tissue.

  17. Optical absorption and heating rate dependent glass transition in vanadyl doped calcium oxy-chloride borate glasses

    NASA Astrophysics Data System (ADS)

    Dahiya, M. S.; Khasa, S.; Agarwal, A.

    2015-04-01

    Some important results pertaining to optical and thermal properties of vanadyl doped oxy-halide glasses in the chemical composition CaCl2-CaO-B2O3 are discussed. These glasses have been prepared by conventional melt quench technique. From X-ray diffraction (XRD) profiles the amorphous nature of the doped glasses has been confirmed. The electronic polarizability is calculated and found to increase with increase in chloride content. The optical absorption spectra have been recorded in the frequency range of 200-3200 nm. Recorded spectra are analyzed to evaluate cut-off wavelength (λcut-off), optical band gap (Eg), band tailing (B), Urbach energy (ΔE) and refractive index (n). Thermal analysis has been carried out for the prepared glasses at three different heating rates viz. 5, 10 and 20 °C/min. The glass transition temperature (Tg) along with thermal activation energy (Ea) corresponding to each heating rate are evaluated from differential scanning calorimetry (DSC) thermographs. It is found that Ea decrease and Tg increase with increase in heating rate. The variation in Tg is also observed with the substitution of calcium chloride in place of calcium oxide. The increasing and higher values of Ea suggest that prepared glasses have good thermal stability. Variation in Tg and Eg suggests that Cl- anions enter into the voids of borate network at low concentrations (<5.0%) and contribute to the network formation at high concentration (>5.0%).

  18. Zinc absorption from composite meals. I. The significance of whest extraction rate, zinc, calcium, and protein content in meals based on bread.

    PubMed

    Sandström, B; Arvidsson, B; Cederblad, A; Björn-Rasmussen, E

    1980-04-01

    The absorption of zinc in man from composite meals based on bread was measured with a radionuclide technique using 65Zn and whole-body counting. Bread was made up from wheat flour of 100 and 72% extraction rate. A lower absolute amount of zinc was absorbed from the white bread compared to the absorption from the same amount of wholemeal bread. When the two types of bread were enriched with zinc chloride the absorption was higher from the white bread than from the wholemeal bread. Addition of calcium in the form of milk products improved the absorption of zinc from a meal with wholemeal bread. A significant positive correlation was found between zinc absorption and the protein content in meals containing milk, cheese, beef, and egg in various combinations with the wholemeal bread.

  19. Correlation between relative growth rate and specific leaf area requires associations of specific leaf area with nitrogen absorption rate of roots.

    PubMed

    Osone, Yoko; Ishida, Atsushi; Tateno, Masaki

    2008-07-01

    Close correlations between specific leaf area (SLA) and relative growth rate (RGR) have been reported in many studies. However, theoretically, SLA by itself has small net positive effect on RGR because any increase in SLA inevitably causes a decrease in area-based leaf nitrogen concentration (LNCa), another RGR component. It was hypothesized that, for a correlation between SLA and RGR, SLA needs to be associated with specific nitrogen absorption rate of roots (SAR), which counteracts the negative effect of SLA on LNCa. Five trees and six herbs were grown under optimal conditions and relationships between SAR and RGR components were analyzed using a model based on balanced growth hypothesis. SLA varied 1.9-fold between species. Simulations predicted that, if SAR is not associated with SLA, this variation in SLA would cause a47% decrease in LNCa along the SLA gradient, leading to a marginal net positive effect on RGR. In reality, SAR was positively related to SLA, showing a 3.9-fold variation, which largely compensated for the negative effect of SLA on LNCa. Consequently, LNCa values were almost constant across species and a positive SLA-RGR relationship was achieved. These results highlight the importance of leaf-root interactions in understanding interspecific differences in RGR.

  20. Rate-based modeling of reactive absorption of CO{sub 2} and H{sub 2}S into aqueous methyldiethanolamine

    SciTech Connect

    Pacheco, M.A.; Rochelle, G.T.

    1998-10-01

    A general framework was developed to model the transport processes that take place during reactive absorption when both rate- and equilibrium-controlled reactions occur in the liquid phase. This framework was applied to the selective absorption of H{sub 2}S from fuel gas containing CO{sub 2} using aqueous methyldiethanolamine. A rate-based distillation column module was used for the column integration. The Maxwell-Stefan and enhancement factor theories were utilized. In packed columns, CO{sub 2} absorption is controlled by diffusion with fast chemical reactions; in trayed columns it is controlled primarily by physical absorption. Gas-film resistance is never significant for CO{sub 2} absorption. For H{sub 2}S absorption, gas- and liquid-film resistances are important, and diffusion of bisulfide controls the liquid-film resistance. Heat effects produce temperatures bulges that can cause equilibrium pinches at the maximum temperature. This phenomenon gives an optimum packing height for the H{sub 2}S removal. Trayed columns are more selective than packed columns for H{sub 2}S removal, primarily because of the larger number of liquid-film mass transfer units.

  1. Determination of the magnetocrystalline anisotropy constant from the frequency dependence of the specific absorption rate in a frozen ferrofluid

    NASA Astrophysics Data System (ADS)

    Mosher, Nathaniel; Perkins-Harbin, Emily; Aho, Brandon; Wang, Lihua; Kumon, Ronald; Rablau, Corneliu; Vaishnava, Prem; Tackett, Ronald; Therapeutic Biomaterials Group Team

    2015-03-01

    Colloidal suspensions of superparamagnetic nanoparticles, known as ferrofluids, are promising candidates for the mediation of magnetic fluid hyperthermia (MFH). In such materials, the dissipation of heat occurs as a result of the relaxation of the particles in an applied ac magnetic field via the Brownian and Neel mechanisms. In order to isolate and study the role of the Neel mechanism in this process, the sample can be frozen, using liquid nitrogen, in order to suppress the Brownian relaxation. In this experiment, dextran-coated Fe3O4 nanoparticles synthesized via co-precipitation and characterized via transmission electron microscopy and dc magnetization are used as MFH mediators over the temperature range between -70 °C to -10 °C (Brownian-suppressed state). Heating the nanoparticles using ac magnetic field (amplitude ~300 Oe), the frequency dependence of the specific absorption rate (SAR) is calculated between 150 kHz and 350 kHz and used to determine the magnetocrystalline anisotropy of the sample. We would like to thank Fluxtrol, Inc. for their help with this project

  2. Multimodal Superparamagnetic Nanoparticles with Unusually Enhanced Specific Absorption Rate for Synergetic Cancer Therapeutics and Magnetic Resonance Imaging.

    PubMed

    Thorat, Nanasaheb D; Bohara, Raghvendra A; Malgras, Victor; Tofail, Syed A M; Ahamad, Tansir; Alshehri, Saad M; Wu, Kevin C-W; Yamauchi, Yusuke

    2016-06-15

    Superparamagnetic nanoparticles (SPMNPs) used for magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH) cancer therapy frequently face trade off between a high magnetization saturation and their good colloidal stability, high specific absorption rate (SAR), and most importantly biological compatibility. This necessitates the development of new nanomaterials, as MFH and MRI are considered to be one of the most promising combined noninvasive treatments. In the present study, we investigated polyethylene glycol (PEG) functionalized La1-xSrxMnO3 (LSMO) SPMNPs for efficient cancer hyperthermia therapy and MRI application. The superparamagnetic nanomaterial revealed excellent colloidal stability and biocompatibility. A high SAR of 390 W/g was observed due to higher colloidal stability leading to an increased Brownian and Neel's spin relaxation. Cell viability of PEG capped nanoparticles is up to 80% on different cell lines tested rigorously using different methods. PEG coating provided excellent hemocompatibility to human red blood cells as PEG functionalized SPMNPs reduced hemolysis efficiently compared to its uncoated counterpart. Magnetic fluid hyperthermia of SPMNPs resulted in cancer cell death up to 80%. Additionally, improved MRI characteristics were also observed for the PEG capped La1-xSrxMnO3 formulation in aqueous medium compared to the bare LSMO. Taken together, PEG capped SPMNPs can be useful for diagnosis, efficient magnetic fluid hyperthermia, and multimodal cancer treatment as the amphiphilicity of PEG can easily be utilized to encapsulate hydrophobic drugs. PMID:27197993

  3. Numerical assessment of the reduction of specific absorption rate by adding high dielectric materials for fetus MRI at 3 T.

    PubMed

    Luo, Minmin; Hu, Can; Zhuang, Yayun; Chen, Wufan; Liu, Feng; Xin, Sherman Xuegang

    2016-08-01

    The specific absorption rate (SAR) is an important issue to be considered in fetus MRI at 3 T due to the high radiofrequency energy deposited inside the body of pregnant woman. The high dielectric material (HDM) has shown its potential for enhancing B1 field and reducing SAR in MRI. The aim of this study is to assess the feasibility of SAR reduction by adding an HDM to the fetus MRI. The feasibility of SAR reduction is numerically assessed in this study, using a birdcage coil in transmission loaded with an electromagnetic pregnant woman model in the SEMCAD-EM solver. The HDMs with different geometric arrangements and dielectric constants are manually optimized. The B1+ ${B_1}^ + $ homogeneity is also considered while calculating the optimized fetus 10 g local SAR among different strategies in the application of HDM. The optimum maximum fetus 10 g local SAR was obtained as 2.25 W/kg, by using two conformal pads placed left and right with the dielectric constant to be 400, reduced by 24.75% compared to that without the HDM. It indicated that the SAR can be significantly reduced with strategic placement of the HDM and the use of HDM may provide a simple, effective and low-cost method for reducing the SAR for the fetus MRI at 3 T. PMID:26985683

  4. Multimodal Superparamagnetic Nanoparticles with Unusually Enhanced Specific Absorption Rate for Synergetic Cancer Therapeutics and Magnetic Resonance Imaging.

    PubMed

    Thorat, Nanasaheb D; Bohara, Raghvendra A; Malgras, Victor; Tofail, Syed A M; Ahamad, Tansir; Alshehri, Saad M; Wu, Kevin C-W; Yamauchi, Yusuke

    2016-06-15

    Superparamagnetic nanoparticles (SPMNPs) used for magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH) cancer therapy frequently face trade off between a high magnetization saturation and their good colloidal stability, high specific absorption rate (SAR), and most importantly biological compatibility. This necessitates the development of new nanomaterials, as MFH and MRI are considered to be one of the most promising combined noninvasive treatments. In the present study, we investigated polyethylene glycol (PEG) functionalized La1-xSrxMnO3 (LSMO) SPMNPs for efficient cancer hyperthermia therapy and MRI application. The superparamagnetic nanomaterial revealed excellent colloidal stability and biocompatibility. A high SAR of 390 W/g was observed due to higher colloidal stability leading to an increased Brownian and Neel's spin relaxation. Cell viability of PEG capped nanoparticles is up to 80% on different cell lines tested rigorously using different methods. PEG coating provided excellent hemocompatibility to human red blood cells as PEG functionalized SPMNPs reduced hemolysis efficiently compared to its uncoated counterpart. Magnetic fluid hyperthermia of SPMNPs resulted in cancer cell death up to 80%. Additionally, improved MRI characteristics were also observed for the PEG capped La1-xSrxMnO3 formulation in aqueous medium compared to the bare LSMO. Taken together, PEG capped SPMNPs can be useful for diagnosis, efficient magnetic fluid hyperthermia, and multimodal cancer treatment as the amphiphilicity of PEG can easily be utilized to encapsulate hydrophobic drugs.

  5. Specific absorption rate dependence on temperature in magnetic field hyperthermia measured by dynamic hysteresis losses (ac magnetometry)

    NASA Astrophysics Data System (ADS)

    Garaio, Eneko; Sandre, Olivier; Collantes, Juan-Mari; Garcia, Jose Angel; Mornet, Stéphane; Plazaola, Fernando

    2015-01-01

    Magnetic nanoparticles (NPs) are intensively studied for their potential use for magnetic hyperthermia, a treatment that has passed a phase II clinical trial against severe brain cancer (glioblastoma) at the end of 2011. Their heating power, characterized by the ‘specific absorption rate (SAR)’, is often considered temperature independent in the literature, mainly because of the difficulties that arise from the measurement methodology. Using a dynamic magnetometer presented in a recent paper, we measure here the thermal dependence of SAR for superparamagnetic iron oxide (maghemite) NPs of four different size-ranges corresponding to mean diameters around 12 nm, 14 nm, 15 nm and 16 nm. The article reports a parametrical study extending from 10 to 60 {}^\\circ C in temperature, from 75 to 1031 kHz in frequency, and from 2 to 24 kA m-1 in magnetic field strength. It was observed that SAR values of smaller NPs decrease with temperature whereas for the larger sample (16 nm) SAR values increase with temperature. The measured variation of SAR with temperature is frequency dependent. This behaviour is fully explained within the scope of linear response theory based on Néel and Brown relaxation processes, using independent magnetic measurements of the specific magnetization and the magnetic anisotropy constant. A good quantitative agreement between experimental values and theoretical values is confirmed in a tri-dimensional space that uses as coordinates the field strength, the frequency and the temperature.

  6. Analysis of the Role of Lead Resistivity in Specific Absorption Rate for Deep Brain Stimulator Leads at 3T MRI

    PubMed Central

    Angelone, Leonardo M.; Ahveninen, Jyrki; Belliveau, John W.; Bonmassar, Giorgio

    2011-01-01

    Magnetic resonance imaging (MRI) on patients with implanted deep brain stimulators (DBSs) can be hazardous because of the antenna-effect of leads exposed to the incident radio-frequency field. This study evaluated electromagnetic field and specific absorption rate (SAR) changes as a function of lead resistivity on an anatomically precise head model in a 3T system. The anatomical accuracy of our head model allowed for detailed modeling of the path of DBS leads between epidermis and the outer table. Our electromagnetic finite difference time domain (FDTD) analysis showed significant changes of 1 g and 10 g averaged SAR for the range of lead resistivity modeled, including highly conductive leads up to highly resistive leads. Antenna performance and whole-head SAR were sensitive to the presence of the DBS leads only within 10%, while changes of over one order of magnitude were observed for the peak 10 g averaged SAR, suggesting that local SAR values should be considered in DBS guidelines. With ρlead = ρcopper, and the MRI coil driven to produce a whole-head SAR without leads of 3.2 W/kg, the 1 g averaged SAR was 1080 W/kg and the 10 g averaged SAR 120 W/kg at the tip of the DBS lead. Conversely, in the control case without leads, the 1 g and 10 g averaged SAR were 0.5 W/kg and 0.6 W/kg, respectively, in the same location. The SAR at the tip of lead was similar with electrically homogeneous and electrically heterogeneous models. Our results show that computational models can support the development of novel lead technology, properly balancing the requirements of SAR deposition at the tip of the lead and power dissipation of the system battery. PMID:20335090

  7. Resonance behaviour of whole-body averaged specific energy absorption rate (SAR) in the female voxel model, NAOMI

    NASA Astrophysics Data System (ADS)

    Dimbylow, Peter

    2005-09-01

    Finite-difference time-domain (FDTD) calculations have been performed of the whole-body averaged specific energy absorption rate (SAR) in a female voxel model, NAOMI, under isolated and grounded conditions from 10 MHz to 3 GHz. The 2 mm resolution voxel model, NAOMI, was scaled to a height of 1.63 m and a mass of 60 kg, the dimensions of the ICRP reference adult female. Comparison was made with SAR values from a reference male voxel model, NORMAN. A broad SAR resonance in the NAOMI values was found around 900 MHz and a resulting enhancement, up to 25%, over the values for the male voxel model, NORMAN. This latter result confirmed previously reported higher values in a female model. The effect of differences in anatomy was investigated by comparing values for 10-, 5- and 1-year-old phantoms rescaled to the ICRP reference values of height and mass which are the same for both sexes. The broad resonance in the NAOMI child values around 1 GHz is still a strong feature. A comparison has been made with ICNIRP guidelines. The ICNIRP occupational reference level provides a conservative estimate of the whole-body averaged SAR restriction. The linear scaling of the adult phantom using different factors in longitudinal and transverse directions, in order to match the ICRP stature and weight, does not exactly reproduce the anatomy of children. However, for public exposure the calculations with scaled child models indicate that the ICNIRP reference level may not provide a conservative estimate of the whole-body averaged SAR restriction, above 1.2 GHz for scaled 5- and 1-year-old female models, although any underestimate is by less than 20%.

  8. Non-mass dependent photodissociation rates of ozone isotopologues from ab-initio absorption cross sections and experimental actinic flux

    NASA Astrophysics Data System (ADS)

    Ndengué, Steve; Jost, Rémy; Gatti, Fabien; Schinke, Reinhard; Madronich, Sasha

    2010-05-01

    The absorption cross sections (XSs) of eighteen isotopologues of the ozone molecule have been calculated in the range of the Chappuis-Huggins-Hartley bands: 15000-55000 cm-1 with special emphasis to those of atmospheric interest: symmetric 16O3, 16O17O16O, and 16O18O16O and asymmetric 17O16O2 and 18O16O2. We have used the MCTDH code which is based on the time propagation of the X(0,0,0) ground state initial wavepacket on the excited state PESs. The XSs have been obtained as the Fourier transform of the autocorrelation function of this wavepacket. The calculations have been performed only for zero total angular momentum and the rotational structure has been modeled numerically. The isotopologue dependence of the overall XSs has been characterized differently in each of the three bands: in the Chappuis band (15000-27000 cm-1) and in the Hartley band (33000-55000 cm-1), the XSs are weakly structured and the isotopologue dependence is globally weak. In contrast, in the Huggins band (27000 to 33000 cm-1) the different XSs are highly structured and their peaks are significantly shifted from those of the 16O3 absolute XS which has been chosen as reference. The Hartley band of each isotopologue can be approximated by a bell shape envelop modeled by a modified Gaussian depending on only four parameters: amplitude, centre, width and asymmetry. The isotopologue dependence of the Hartley band resumes only into tiny differences between these parameters. The dependence of the Chappuis band is also weak. The isotopologue shifts of peaks in the Huggins bands induce a significant dependence of the photodissociation rates because these rates are the integral of the product of the XS by the actinic flux. Below 30 km, the actinic flux displays a tremendous attenuation in the range of the Hartley band because the solar flux is strongly absorbed by the stratospheric ozone, almost exclusively by the 16O3 isotopologue. This implies two consequences: a) the actinic flux reproduces

  9. Changes in ruminal volatile fatty acid production and absorption rate during the dry period and early lactation as affected by rate of increase of concentrate allowance.

    PubMed

    Dieho, K; Dijkstra, J; Schonewille, J T; Bannink, A

    2016-07-01

    The aim of the present experiment was to study changes in volatile fatty acid (VFA) production using an isotope dilution technique, and changes in VFA fractional absorption rate (kaVFA) using a buffer incubation technique (BIT) during the dry period and early lactation, as affected by the postpartum (pp) rate of increase of concentrate allowance. The current results are complementary to previously reported changes on rumen papillae morphology from the same experiment. From 50 d antepartum to 80 d pp, VFA production rate was measured 5 times and kaVFA was measured 10 times in 12 rumen-cannulated Holstein Friesian cows. Cows had free access to a mixed ration, consisting of grass and corn silage, soybean meal, and (dry period only) chopped straw. Treatment consisted of either a rapid (RAP; 1.0 kg of DM/d; n=6) or gradual (GRAD; 0.25 kg of DM/d; n=6) increase of concentrate allowance (up to 10.9 kg of DM/d), starting at 4 d pp, aimed at creating a contrast in rumen-fermentable organic matter intake. For the BIT, rumen contents were evacuated, the rumen washed, and a standardized buffer fluid introduced [120 mM VFA, 60% acetic (Ac), 25% propionic (Pr), and 15% butyric (Bu) acid; pH 5.9 and Co-EDTA as fluid passage marker]. For the isotope dilution technique, a pulse-dose of (13)C-labeled Ac, Pr, and Bu and Co-EDTA as fluid passage marker was infused. The rate of total VFA production was similar between treatments and was 2 times higher during the lactation (114 mol/d) than the dry period (53 mol/d). Although papillae surface area at 16, 30, and 44 d pp was greater in RAP than GRAD, Bu and Ac production at these days did not differ between RAP and GRAD, whereas at 16 d pp RAP produced more Pr than GRAD. These results provide little support for the particular proliferative effects of Bu on papillae surface area. Similar to developments in papillae surface area in the dry period and early lactation, the kaVFA (per hour), measured using the BIT, decreased from 0.45 (Ac), 0

  10. Monomeric C-phycocyanin at room temperature and 77 K. Resolution of the absorption and fluorescence spectra of the individual chromophores and the energy-transfer rate constants

    SciTech Connect

    Debreczeny, M.P.; Sauer, K. Univ. of California, Berkeley, CA ); Zhou, J.; Bryant, D.A. )

    1993-09-23

    At both room temperature (RT) and 77 K, the absorption and fluorescence spectra of the three individual chromophore types ([alpha][sub 84], [beta][sub 84], and [beta][sub 155]) found in monomeric C-phycocyanin ([alpha][sup PC][beta][sup PC]), isolated from the cyanobacterium Synechococcus sp. PCC 7002, were resolved along with the rates of energy transfer between the chromophores. The cpcB/C155S mutant, whose PC is missing the [beta][sub 155] chromophore, was useful in effecting this resolution. At RT, the single broad peak in the visible region of the absorption spectrum of ([alpha][sup PC][beta][sup PC]) was resolved into its three-component spectra by comparing the steady-state absorption spectra of the isolated wild-type [alpha] subunit of PC ([alpha][sup PC]) (containing only the [alpha][sub 84] chromophore) with those of the monomeric PCs isolated from the mutant strain ([alpha][sup PC][beta]*) and the wild-type strain ([alpha][sup PC][beta][sup PC]). At 77 K, the visible region of the absorption spectrum of ([alpha][sup PC][beta][sup PC]) splits into two peaks. This partial resolution at 77 K of the chromophore spectra of ([alpha][sup PC][beta][sup PC]) when compared with the 77 K absorption spectra of [alpha][sup PC], [beta][sup PC], and ([alpha][sup PC][beta]*) provided a confirmation of our RT assignments of the chromophore absorption spectra. 38 refs., 9 figs., 6 tabs.

  11. Enhancement of the dissolution rate and gastrointestinal absorption of pranlukast as a model poorly water-soluble drug by grinding with gelatin.

    PubMed

    Chono, Sumio; Takeda, Eri; Seki, Toshinobu; Morimoto, Kazuhiro

    2008-01-22

    The effect of grinding with gelatin on the dissolution behavior and gastrointestinal absorption of a poorly water-soluble drug was evaluated using the antiasthmatic agent, pranlukast, as a model poorly water-soluble drug. A ground pranlukast-gelatin mixture was prepared by grinding equal quantities of pranlukast and gelatin. In the dissolution testing, the dissolution rate of pranlukast in the suspension of the ground pranlukast-gelatin mixture under conditions of pH 3.0, 5.0 and 7.0 was markedly faster than that in the suspension of pranlukast. According to powder X-ray diffractometry (PXRD) and differential scanning calorimetry (DSC) analysis, the enhanced dissolution rate of pranlukast produced by grinding with gelatin was caused by changing the crystalline state of pranlukast into an amorphous state. In an animal experiment, the bioavailability of pranlukast following oral administration of the ground pranlukast-gelatin mixture to rats was threefold greater than that following administration of pranlukast. In the in vitro permeation experiment, the amount of permeated pranlukast through Caco-2 cell monolayers after application of the ground pranlukast-gelatin mixture was greater than that after application of pranlukast. These results suggest that the enhancement of the gastrointestinal absorption of pranlukast by grinding with gelatin is due to enhancement of the dissolution rate. Grinding a poorly water-soluble drug with gelatin is a useful method of enhancing its gastrointestinal absorption.

  12. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties. PMID:21571541

  13. The impact of cell-specific absorption properties on the correlation of electron transport rates measured by chlorophyll fluorescence and photosynthetic oxygen production in planktonic algae.

    PubMed

    Blache, Ulrich; Jakob, Torsten; Su, Wanwen; Wilhelm, Christian

    2011-08-01

    Photosynthesis-irradiance (P-E)-curves describe the photosynthetic performance of autotrophic organisms. From these P-E-curves the photosynthetic parameters α-slope, P(max), and E(k) can be deduced which are often used to characterize and to compare different organisms or organisms in acclimation to different environmental conditions. Particularly, for in situ-measurements of P-E curves of phytoplankton the analysis of variable chlorophyll fluorescence proved its potential as a sensitive and rapid method. By using Chlorella vulgaris (Trebouxiophyceae), Nannochloropsis salina (Eustigmatophyceae), Skeletonema costatum and Cyclotella meneghiniana (Bacillariophyceae), the present study investigated the influence of cellular bio-optical properties on the correlation of the photosynthetic parameters derived from fluorescence-based P-E-curves with photosynthetic parameters obtained from the measurement of oxygen evolution. It is demonstrated that small planktonic algae show a wide range of cellular absorptivity which was subject to species-specifity, growth stage and environmental conditions, e.g. nutrient limitation. This variability in bio-optical properties resulted in a great deviation of relative electron transport rates (rETRs) from oxygen-based photosynthesis rates. Thus, the photosynthetic parameters α-slope and P(max) derived from rETRs strongly depend on the specific cellular absorptivity and cannot be used to compare the photosynthetic performance of cells with different optical properties. However, it was shown that E(k) is independent of cellular absorptivity and could be used to compare samples with unknown optical properties.

  14. Addition of sodium bicarbonate to either 1 or 2 feedings of colostrum replacer: effect on uptake and rate of absorption of immunoglobulin G in neonatal calves.

    PubMed

    Cabral, R G; Kent, E J; Haines, D M; Erickson, P S

    2012-06-01

    Forty Holstein dairy calves were blocked by birth date and sex, and randomly assigned to 1 of 4 treatments within each block to elucidate the effect of feeding regimen and sodium bicarbonate (NaHCO₃) supplementation on absorption of IgG from colostrum replacer (CR). Calves received CR containing 191.4 g of IgG fed either in 1 feeding at 0 h (within 45 min of birth), with or without 30 g of NaHCO₃, or in 2 feedings (127.6 g of IgG at 0 h, with or without 20 g of NaHCO₃, and 63.8 g of IgG at 6 h, with or without 10 g of NaHCO₃). The treatments were (1) 1 feeding of CR+0 g of NaHCO₃; (2) 1 feeding of CR+30 g of NaHCO₃; (3) 2 feedings of CR+0 g of NaHCO₃; and (4) 2 feedings of CR+30 g total of NaHCO₃. Only calves born with no dystocia were used on this study. Blood samples were taken at 0, 6, 12, 18, and 24h postpartum and were analyzed for IgG using a radial immunoassay. Results indicated that, individually, feeding regimen and NaHCO₃ treatments had no effect. However, the interaction was significant for 24-h IgG and area under the curve, and showed a trend for apparent efficiency of absorption. Absorption rate data indicated that, for calves fed within 45 min of birth, most IgG absorption occurred in the first 6 h after birth. From 6 to 12 h postpartum, IgG absorption started to decrease; however, IgG absorption remained higher for calves fed in a single feeding than in 2 feedings. These data indicated that NaHCO₃ may increase IgG absorption when calves are fed colostrum in a single feeding but is not beneficial when colostrum is fed in 2 feedings.

  15. Enhanced Rates of Hydrogen Absorption Resulting from Oxidation of Pd and Internal Oxidation of Pd-Al Alloys

    SciTech Connect

    Shanahan, K.L.

    1999-08-20

    The goal of this research was the determination of the relative rates before and after internal oxidation of Pd--Al alloys and oxidation (Pd) and this is independent of whether heat transfer is the rate-limiting step for the internally oxidized Pd--Al alloys rather than a more fundamental step.

  16. Dynamic absorption and scattering of water and hydrogel during high-repetition-rate (>100 MHz) burst-mode ultrafast-pulse laser ablation.

    PubMed

    Qian, Zuoming; Covarrubias, Andrés; Grindal, Alexander W; Akens, Margarete K; Lilge, Lothar; Marjoribanks, Robin S

    2016-06-01

    High-repetition-rate burst-mode ultrafast-laser ablation and disruption of biological tissues depends on interaction of each pulse with the sample, but under those particular conditions which persist from previous pulses. This work characterizes and compares the dynamics of absorption and scattering of a 133-MHz repetition-rate, burst-mode ultrafast-pulse laser, in agar hydrogel targets and distilled water. The differences in energy partition are quantified, pulse-by-pulse, using a time-resolving integrating-sphere-based device. These measurements reveal that high-repetition-rate burst-mode ultrafast-laser ablation is a highly dynamical process affected by the persistence of ionization, dissipation of plasma plume, neutral material flow, tissue tensile strength, and the hydrodynamic oscillation of cavitation bubbles. PMID:27375948

  17. Dynamic absorption and scattering of water and hydrogel during high-repetition-rate (>100 MHz) burst-mode ultrafast-pulse laser ablation

    PubMed Central

    Qian, Zuoming; Covarrubias, Andrés; Grindal, Alexander W.; Akens, Margarete K.; Lilge, Lothar; Marjoribanks, Robin S.

    2016-01-01

    High-repetition-rate burst-mode ultrafast-laser ablation and disruption of biological tissues depends on interaction of each pulse with the sample, but under those particular conditions which persist from previous pulses. This work characterizes and compares the dynamics of absorption and scattering of a 133-MHz repetition-rate, burst-mode ultrafast-pulse laser, in agar hydrogel targets and distilled water. The differences in energy partition are quantified, pulse-by-pulse, using a time-resolving integrating-sphere-based device. These measurements reveal that high-repetition-rate burst-mode ultrafast-laser ablation is a highly dynamical process affected by the persistence of ionization, dissipation of plasma plume, neutral material flow, tissue tensile strength, and the hydrodynamic oscillation of cavitation bubbles. PMID:27375948

  18. Determination of drug absorption rate in time-variant disposition by direct deconvolution using beta clearance correction and end-constrained non-parametric regression.

    PubMed

    Neelakantan, S; Veng-Pedersen, P

    2005-11-01

    A novel numerical deconvolution method is presented that enables the estimation of drug absorption rates under time-variant disposition conditions. The method involves two components. (1) A disposition decomposition-recomposition (DDR) enabling exact changes in the unit impulse response (UIR) to be constructed based on centrally based clearance changes iteratively determined. (2) A non-parametric, end-constrained cubic spline (ECS) input response function estimated by cross-validation. The proposed DDR-ECS method compensates for disposition changes between the test and the reference administrations by using a "beta" clearance correction based on DDR analysis. The representation of the input response by the ECS method takes into consideration the complex absorption process and also ensures physiologically realistic approximations of the response. The stability of the new method to noisy data was evaluated by comprehensive simulations that considered different UIRs, various input functions, clearance changes and a novel scaling of the input function that includes the "flip-flop" absorption phenomena. The simulated input response was also analysed by two other methods and all three methods were compared for their relative performances. The DDR-ECS method provides better estimation of the input profile under significant clearance changes but tends to overestimate the input when there were only small changes in the clearance.

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

    SciTech Connect

    Adams, M.E.; Marshall, T.L.; Rowley, R.L.

    1998-07-01

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

  20. Improved Shock Tube Measurement of the CH4 + Ar = CH3 + H + Ar Rate Constant using UV Cavity-Enhanced Absorption Spectroscopy of CH3.

    PubMed

    Wang, Shengkai; Davidson, David F; Hanson, Ronald K

    2016-07-21

    We report an improved measurement for the rate constant of methane dissociation in argon (CH4 + Ar = CH3 + H + Ar) behind reflected shock waves. The experiment was conducted using a sub-parts per million sensitivity CH3 diagnostic recently developed in our laboratory based on ultraviolet cavity-enhanced absorption spectroscopy. The high sensitivity of this diagnostic allowed for measurements of quantitatively resolved CH3 time histories during the initial stage of CH4 pyrolysis, where the reaction system is clean and free from influences of secondary reactions and temperature change. This high sensitivity also allowed extension of our measurement range to much lower temperatures (<1500 K). The current-reflected shock measurements were performed at temperatures between 1487 and 1866 K and pressures near 1.7 atm, resulting in the following Arrhenius rate constant expression for the title reaction: k(1.7 atm) = 3.7 × 10(16) exp(-42 200 K/T) cm(3)/mol·s, with a 2σ uncertainty factor of 1.25. The current data are in good consensus with various theoretical and review studies, but at the low temperature end they suggest a slightly higher (up to 35%) rate constant compared to these previous results. A re-evaluation of previous and current experimental data in the falloff region was also performed, yielding updated expressions for both the low-pressure limit and the high-pressure limit rate constants and improved agreement with all existing data. PMID:27380878

  1. Measuring the Absorption Rate of CO2 in Nonaqueous CO2-Binding Organic Liquid Solvents with a Wetted-Wall Apparatus.

    PubMed

    Mathias, Paul M; Zheng, Feng; Heldebrant, David J; Zwoster, Andy; Whyatt, Greg; Freeman, Charles M; Bearden, Mark D; Koech, Phillip

    2015-11-01

    The kinetics of the absorption of CO2 into two nonaqueous CO2-binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model.

  2. Influence of the oral dissolution time on the absorption rate of locally administered solid formulations for oromucosal use: the flurbiprofen lozenges paradigm.

    PubMed

    Imberti, Roberto; De Gregori, Simona; Lisi, Lucia; Navarra, Pierluigi

    2014-01-01

    Flurbiprofen is a nonsteroidal anti-inflammatory agent preferentially used for local oromucosal treatment of painful and/or inflammatory conditions of the oropharynx such as gingivitis, stomatitis, periodontitis, pharyngitis and laryngitis. In this study, we have investigated the bioavailability of a new generic formulation of flurbiprofen lozenges developed by Epifarma Srl, compared to the originator Benactiv Gola® taken as reference. Within the framework of a formal bioequivalence study, we investigated in particular the putative influence of oral dissolution time (i.e. the time spent suckling the lozenge from its intake to complete dissolution) on the absorption rate, and the contribution of this factor to the total variability of plasma flurbiprofen during absorption. We found that the amount of flurbiprofen absorbed into the systemic circulation is not significantly higher for the test drug compared to that of the reference product. We observed that the length of oral dissolution time is inversely correlated to 10-min flurbiprofen plasma levels in the test but not in the reference formulation. We estimated that oral dissolution time accounts for about 14% of overall variability in flurbiprofen plasma 10 min after test drug administration.

  3. Measuring the Absorption Rate of CO2 in Nonaqueous CO2-Binding Organic Liquid Solvents with a Wetted-Wall Apparatus.

    PubMed

    Mathias, Paul M; Zheng, Feng; Heldebrant, David J; Zwoster, Andy; Whyatt, Greg; Freeman, Charles M; Bearden, Mark D; Koech, Phillip

    2015-11-01

    The kinetics of the absorption of CO2 into two nonaqueous CO2-binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model. PMID:26377774

  4. Influence of the oral dissolution time on the absorption rate of locally administered solid formulations for oromucosal use: the flurbiprofen lozenges paradigm.

    PubMed

    Imberti, Roberto; De Gregori, Simona; Lisi, Lucia; Navarra, Pierluigi

    2014-01-01

    Flurbiprofen is a nonsteroidal anti-inflammatory agent preferentially used for local oromucosal treatment of painful and/or inflammatory conditions of the oropharynx such as gingivitis, stomatitis, periodontitis, pharyngitis and laryngitis. In this study, we have investigated the bioavailability of a new generic formulation of flurbiprofen lozenges developed by Epifarma Srl, compared to the originator Benactiv Gola® taken as reference. Within the framework of a formal bioequivalence study, we investigated in particular the putative influence of oral dissolution time (i.e. the time spent suckling the lozenge from its intake to complete dissolution) on the absorption rate, and the contribution of this factor to the total variability of plasma flurbiprofen during absorption. We found that the amount of flurbiprofen absorbed into the systemic circulation is not significantly higher for the test drug compared to that of the reference product. We observed that the length of oral dissolution time is inversely correlated to 10-min flurbiprofen plasma levels in the test but not in the reference formulation. We estimated that oral dissolution time accounts for about 14% of overall variability in flurbiprofen plasma 10 min after test drug administration. PMID:25277061

  5. The COS/UVES absorption survey of the Magellanic stream. III. Ionization, total mass, and inflow rate onto the Milky Way

    SciTech Connect

    Fox, Andrew J.; Thom, Christopher; Tumlinson, Jason; Ely, Justin; Kumari, Nimisha; Wakker, Bart P.; Hernandez, Audra K.; Haffner, L. Matthew; Barger, Kathleen A.; Lehner, Nicolas; Howk, J. Christopher; Richter, Philipp; Charlton, Jane C.; Westmeier, Tobias; Misawa, Toru; Rodriguez-Hidalgo, Paola

    2014-06-01

    Dynamic interactions between the two Magellanic Clouds have flung large quantities of gas into the halo of the Milky Way. The result is a spectacular arrangement of gaseous structures, including the Magellanic Stream, the Magellanic Bridge, and the Leading Arm (collectively referred to as the Magellanic System). In this third paper of a series studying the Magellanic gas in absorption, we analyze the gas ionization level using a sample of 69 Hubble Space Telescope/Cosmic Origins Spectrograph sightlines that pass through or within 30° of the 21 cm emitting regions. We find that 81% (56/69) of the sightlines show UV absorption at Magellanic velocities, indicating that the total cross-section of the Magellanic System is ≈11,000 deg{sup 2}, or around one-quarter of the entire sky. Using observations of the Si III/Si II ratio together with Cloudy photoionization modeling, we calculate the total gas mass (atomic plus ionized) of the Magellanic System to be ≈2.0 × 10{sup 9} M {sub ☉} (d/55 kpc){sup 2}, with the ionized gas contributing around three times as much mass as the atomic gas. This is larger than the current-day interstellar H I mass of both Magellanic Clouds combined, indicating that they have lost most of their initial gas mass. If the gas in the Magellanic System survives to reach the Galactic disk over its inflow time of ∼0.5-1.0 Gyr, it will represent an average inflow rate of ∼3.7-6.7 M {sub ☉} yr{sup –1}, potentially raising the Galactic star formation rate. However, multiple signs of an evaporative interaction with the hot Galactic corona indicate that the Magellanic gas may not survive its journey to the disk fully intact and will instead add material to (and cool) the corona.

  6. A Bottom-Up Whole-Body Physiologically Based Pharmacokinetic Model to Mechanistically Predict Tissue Distribution and the Rate of Subcutaneous Absorption of Therapeutic Proteins.

    PubMed

    Gill, Katherine L; Gardner, Iain; Li, Linzhong; Jamei, Masoud

    2016-01-01

    The ability to predict subcutaneous (SC) absorption rate and tissue distribution of therapeutic proteins (TPs) using a bottom-up approach is highly desirable early in the drug development process prior to clinical data being available. A whole-body physiologically based pharmacokinetic (PBPK) model, requiring only a few drug parameters, to predict plasma and interstitial fluid concentrations of TPs in humans after intravenous and subcutaneous dosing has been developed. Movement of TPs between vascular and interstitial spaces was described by considering both convection and diffusion processes using a 2-pore framework. The model was optimised using a variety of literature sources, such as tissue lymph/plasma concentration ratios in humans and animals, information on the percentage of dose absorbed following SC dosing via lymph in animals and data showing loss of radiolabelled IgG from the SC dosing site in humans. The resultant model was used to predict t max and plasma concentration profiles for 12 TPs (molecular weight 8-150 kDa) following SC dosing. The predicted plasma concentration profiles were generally comparable to observed data. t max was predicted within 3-fold of reported values, with one third of the predictions within 0.8-1.25-fold. There was no systematic bias in simulated C max values, although a general trend for underprediction of t max was observed. No clear trend between prediction accuracy of t max and TP isoelectric point or molecular size was apparent. The mechanistic whole-body PBPK model described here can be applied to predict absorption rate of TPs into blood and movement into target tissues following SC dosing.

  7. The relationship of temperature rise to specific absorption rate and current in the human leg for exposure to electromagnetic radiation in the high frequency band.

    PubMed

    Wainwright, P R

    2003-10-01

    Of the biological effects of human exposure to radiofrequency and microwave radiation, the best-established are those due to elevation of tissue temperature. To prevent harmful levels of heating, restrictions have been proposed on the specific absorption rate (SAR). However, the relationship between SAR and temperature rise is not an invariant, since not only the heat capacity but also the efficiency of heat dissipation varies between different tissues and exposure scenarios. For small enough SAR, the relationship is linear and may be characterized by a 'heating factor' deltaT/SAR. Under whole-body irradiation the SAR may be particularly high in the ankles due to the concentration of current flowing through a relatively small cross-sectional area. In a previous paper, the author has presented calculations of the SAR distribution in a human leg in the high frequency (HF) band. In this paper, the heating factor for this situation is derived using a finite element approximation of the Pennes bioheat equation. The sensitivity of the results to different blood perfusion rates is investigated, and a simple local thermoregulatory model is applied. Both time-dependent and steady-state solutions are considered. Results confirm the appropriateness of the ICNIRP reference level of 100 mA on current through the leg, but suggest that at higher currents significant thermoregulatory adjustments to muscle blood flow will occur.

  8. High-accuracy measurements of OH(•) reaction rate constants and IR and UV absorption spectra: ethanol and partially fluorinated ethyl alcohols.

    PubMed

    Orkin, Vladimir L; Khamaganov, Victor G; Martynova, Larissa E; Kurylo, Michael J

    2011-08-11

    Rate constants for the gas phase reactions of OH(•) radicals with ethanol and three fluorinated ethyl alcohols, CH(3)CH(2)OH (k(0)), CH(2)FCH(2)OH (k(1)), CHF(2)CH(2)OH (k(2)), and CF(3)CH(2)OH (k(3)) were measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 to 370 K. The Arrhenius plots were found to exhibit noticeable curvature for all four reactions. The temperature dependences of the rate constants can be represented by the following expressions over the indicated temperature intervals: k(0)(220-370 K) = 5.98 × 10(-13)(T/298)(1.99) exp(+515/T) cm(3) molecule(-1) s(-1), k(0)(220-298 K) = (3.35 ± 0.06) × 10(-12) cm(3) molecule(-1) s(-1) [for atmospheric modeling purposes, k(0)(T) is essentially temperature-independent below room temperature, k(0)(220-298 K) = (3.35 ± 0.06) × 10(-12) cm(3) molecule(-1) s(-1)], k(1)(230-370 K) = 3.47 × 10(-14)(T/298)(4.49) exp(+977/T) cm(3) molecule(-1) s(-1), k(2)(220-370 K) = 3.87 × 10(-14)(T/298)(4.25) exp(+578/T) cm(3) molecule(-1) s(-1), and k(3)(220-370 K) = 2.48 × 10(-14)(T/298)(4.03) exp(+418/T) cm(3) molecule(-1) s(-1). The atmospheric lifetimes due to reactions with tropospheric OH(•) were estimated to be 4, 16, 62, and 171 days, respectively, under the assumption of a well-mixed atmosphere. UV absorption cross sections of all four ethanols were measured between 160 and 215 nm. The IR absorption cross sections of the three fluorinated ethanols were measured between 400 and 1900 cm(-1), and their global warming potentials were estimated.

  9. Relationship between peak spatial-averaged specific absorption rate and peak temperature elevation in human head in frequency range of 1-30 GHz

    NASA Astrophysics Data System (ADS)

    Morimoto, Ryota; Laakso, Ilkka; De Santis, Valerio; Hirata, Akimasa

    2016-07-01

    This study investigates the relationship between the peak temperature elevation and the peak specific absorption rate (SAR) averaged over 10 g of tissue in human head models in the frequency range of 1-30 GHz. As a wave source, a half-wave dipole antenna resonant at the respective frequencies is located in the proximity of the pinna. The bioheat equation is used to evaluate the temperature elevation by employing the SAR, which is computed by electromagnetic analysis, as a heat source. The computed SAR is post-processed by calculating the peak spatial-averaged SAR with six averaging algorithms that consider different descriptions provided in international guidelines and standards, e.g. the number of tissues allowed in the averaging volume, different averaging shapes, and the consideration of the pinna. The computational results show that the SAR averaging algorithms excluding the pinna are essential when correlating the peak temperature elevation in the head excluding the pinna. In the averaging scheme considering an arbitrary shape, for better correlation, multiple tissues should be included in the averaging volume rather than a single tissue. For frequencies higher than 3-4 GHz, the correlation for peak temperature elevation in the head excluding the pinna is modest for the different algorithms. The 95th percentile value of the heating factor as well as the mean and median values derived here would be helpful for estimating the possible temperature elevation in the head.

  10. Comparison of FDTD-calculated specific absorption rate in adults and children when using a mobile phone at 900 and 1800 MHz

    NASA Astrophysics Data System (ADS)

    Martínez-Búrdalo, M.; Martín, A.; Anguiano, M.; Villar, R.

    2004-01-01

    In this paper, the specific absorption rate (SAR) in scaled human head models is analysed to study possible differences between SAR in the heads of adults and children and for assessment of compliance with the international safety guidelines, while using a mobile phone. The finite-difference time-domain method (FDTD) has been used for calculating SAR values for models of both children and adults, at 900 and 1800 MHz. Maximum 1 g averaged SAR (SAR1 g) and maximum 10 g averaged SAR (SAR10 g) have been calculated in adults and scaled head models for comparison and assessment of compliance with ANSI/IEEE and European guidelines. Results show that peak SAR1 g and peak SAR10 g all trend downwards with decreasing head size but as head size decreases, the percentage of energy absorbed in the brain increases. So, higher SAR in children's brains can be expected depending on whether the thickness of their skulls and surrounding tissues actually depends on age. The SAR in eyes of different sizes, as a critical organ, has also been studied and very similar distributions for the full size and the scaled models have been obtained. Standard limits can only be exceeded in the unpractical situation where the antenna is located at a very short distance in front of the eye.

  11. Proton Resonance Spectroscopy Study of the Effects of L-Ornithine-L-Aspartate on the Development of Encephalopathy, Using Localization Pulses with Reduced Specific Absorption Rate

    NASA Astrophysics Data System (ADS)

    Slotboom, J.; Vogels, B. A. P. M.; Dehaan, J. G.; Creyghton, J. H. N.; Quack, G.; Chamuleau, R. A. F. M.; Bovee, W. M. M. J.

    Using the SADLOVE ( single-shot adiabatic localized volume excitation) localization technique with reduced specific absorption rate phase-compensated 2π pulses for localization, in vivo rat brain spectra were obtained in order to study the possible beneficial effects of L-ornithine-L-aspartate (OA) on the development of encephalopathy induced by hyperammonemia in portacaval shunted rats, an experimental model for subacute hepatic encephalopathy. The in vivo1H spectra were quantified using a conjugate-gradient-based frequency-domain fitting procedure. OA treatment resulted in an about threefold lower increase in train lactate ( P < 0.0001) and a slower increase of brain glutamine ( P = 0.022) concentration. However, these changes in brain metabolism, including a significantly lower ammonia concentration during OA treatment, were not associated with a sig significant improvement in clinical symptoms of encephalopathy, suggesting either insufficient decrease in brain ammonia concentration or another effect of OA treatment counteracting the lowering effect on blood and brain ammonia and on brain glutamine and lactate. It is concluded that localized in vivo1H MRS of the brain in combination with other analytical techniques, such as in vivo microdialysis, is helpful in explaining pathophysiological changes during hyperammonemia-induced encephalopathy.

  12. Relationship between peak spatial-averaged specific absorption rate and peak temperature elevation in human head in frequency range of 1–30 GHz

    NASA Astrophysics Data System (ADS)

    Morimoto, Ryota; Laakso, Ilkka; De Santis, Valerio; Hirata, Akimasa

    2016-07-01

    This study investigates the relationship between the peak temperature elevation and the peak specific absorption rate (SAR) averaged over 10 g of tissue in human head models in the frequency range of 1–30 GHz. As a wave source, a half-wave dipole antenna resonant at the respective frequencies is located in the proximity of the pinna. The bioheat equation is used to evaluate the temperature elevation by employing the SAR, which is computed by electromagnetic analysis, as a heat source. The computed SAR is post-processed by calculating the peak spatial-averaged SAR with six averaging algorithms that consider different descriptions provided in international guidelines and standards, e.g. the number of tissues allowed in the averaging volume, different averaging shapes, and the consideration of the pinna. The computational results show that the SAR averaging algorithms excluding the pinna are essential when correlating the peak temperature elevation in the head excluding the pinna. In the averaging scheme considering an arbitrary shape, for better correlation, multiple tissues should be included in the averaging volume rather than a single tissue. For frequencies higher than 3–4 GHz, the correlation for peak temperature elevation in the head excluding the pinna is modest for the different algorithms. The 95th percentile value of the heating factor as well as the mean and median values derived here would be helpful for estimating the possible temperature elevation in the head.

  13. Effect of a hands-free wire on specific absorption rate for a waist-mounted 1.8 GHz cellular telephone handset

    NASA Astrophysics Data System (ADS)

    Troulis, S. E.; Scanlon, W. G.; Evans, N. E.

    2003-06-01

    A common feature of cellular telephony is the use of a 'hands-free' audio extension lead connected to a waist-worn handset. Interaction between the transmitting antenna, the wire and the user's body can occur, with detrimental effects including polar pattern degradation, reduced efficiency and localized increases in specific absorption rate (SAR). Using a realistic full-body model of an adult male, finite difference time domain analysis was employed to investigate the coupling between a hip-mounted 1.8 GHz handset fitted with a monopole antenna and a 1 m long wire representing a hands-free wire. Conduction current densities were computed for three identifiable coupling modes: magnetic-only, conductive-only and combined conductive-and-magnetic. Magnetic-only coupling was dominant. Without the lead, placing the handset at waist height led to a 42.8% increase in the total energy deposited in the body, compared to use at the head. Introducing the lead further increased the body loss, with a reduction in system radiation efficiency from 52% to 43.7%. Without the hands-free lead, the peak 1 g and 10 g SARs were 0.450 W kg-1 and 0.265 W kg-1, respectively, for 125 mW transmit power. With the hands-free lead connected, these values increased to 1.14 W kg-1 and 0.430 W kg-1, respectively.

  14. Analysis of in situ electric field and specific absorption rate in human models for wireless power transfer system with induction coupling

    NASA Astrophysics Data System (ADS)

    Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; Onishi, Teruo

    2014-07-01

    This study investigates the specific absorption rate (SAR) and the in situ electric field in anatomically based human models for the magnetic field from an inductive wireless power transfer system developed on the basis of the specifications of the wireless power consortium. The transfer system consists of two induction coils covered by magnetic sheets. Both the waiting and charging conditions are considered. The transfer frequency considered in this study is 140 kHz, which is within the range where the magneto-quasi-static approximation is valid. The SAR and in situ electric field in the chest and arm of the models are calculated by numerically solving the scalar potential finite difference equation. The electromagnetic modelling of the coils in the wireless power transfer system is verified by comparing the computed and measured magnetic field distributions. The results indicate that the peak value of the SAR averaged over a 10 g of tissue and that of the in situ electric field are 72 nW kg-1 and 91 mV m-1 for a transmitted power of 1 W, Consequently, the maximum allowable transmitted powers satisfying the exposure limits of the SAR (2 W kg-1) and the in situ electric field (18.9 V m-1) are found to be 28 MW and 43 kW. The computational results show that the in situ electric field in the chest is the most restrictive factor when compliance with the wireless power transfer system is evaluated according to international guidelines.

  15. The relationship between specific absorption rate and temperature elevation in anatomically based human body models for plane wave exposure from 30 MHz to 6 GHz

    NASA Astrophysics Data System (ADS)

    Hirata, Akimasa; Laakso, Ilkka; Oizumi, Takuya; Hanatani, Ryuto; Chan, Kwok Hung; Wiart, Joe

    2013-02-01

    According to the international safety guidelines/standard, the whole-body-averaged specific absorption rate (Poljak et al 2003 IEEE Trans. Electromagn. Compat. 45 141-5) and the peak spatial average SAR are used as metrics for human protection from whole-body and localized exposures, respectively. The IEEE standard (IEEE 2006 IEEE C95.1) indicates that the upper boundary frequency, over which the whole-body-averaged SAR is deemed to be the basic restriction, has been reduced from 6 to 3 GHz, because radio-wave energy is absorbed around the body surface when the frequency is increased. However, no quantitative discussion has been provided to support this description especially from the standpoint of temperature elevation. It is of interest to investigate the maximum temperature elevation in addition to the core temperature even for a whole-body exposure. In the present study, using anatomically based human models, we computed the SAR and the temperature elevation for a plane-wave exposure from 30 MHz to 6 GHz, taking into account the thermoregulatory response. As the primary result, we found that the ratio of the core temperature elevation to the whole-body-averaged SAR is almost frequency independent for frequencies below a few gigahertz; the ratio decreases above this frequency. At frequencies higher than a few gigahertz, core temperature elevation for the same whole-body averaged SAR becomes lower due to heat convection from the skin to air. This lower core temperature elevation is attributable to skin temperature elevation caused by the power absorption around the body surface. Then, core temperature elevation even for whole-body averaged SAR of 4 W kg-1 with the duration of 1 h was at most 0.8 °C, which is smaller than a threshold considered in the safety guidelines/standard. Further, the peak 10 g averaged SAR is correlated with the maximum body temperature elevations without extremities and pinna over the frequencies considered. These findings were confirmed

  16. Numerical analysis of specific absorption rate in the human head due to a 13.56 MHz RFID-based intra-ocular pressure measurement system.

    PubMed

    Hirtl, Rene; Schmid, Gernot

    2013-09-21

    A modern wireless intra-ocular pressure monitoring system, based on 13.56 MHz inductively coupled data transmission, was dosimetrically analyzed with respect to the specific absorption rate (SAR) induced inside the head and the eye due to the electromagnetic field exposure caused by the reader antenna of the transmission system. The analysis was based on numerical finite difference time domain computations using a high resolution anatomical eye model integrated in a modern commercially available anatomical model of a male head. Three different reader antenna configurations, a 7-turn elliptic (30 mm × 50 mm) antenna at 12 mm distance from the eye, a flexible circular antenna (60 mm diameter, 8 turns on 2 mm substrate) directly attached to the skin, and a circular 7-turn antenna (30 mm diameter at 12 mm distance to the eye) were analyzed, respectively. Possible influences of the eye-lid status (closed or opened) and the transponder antenna contained in a contact lens directly attached to the eye were taken into account. The results clearly demonstrated that for typical reader antenna currents required for proper data transmission, the SAR values remain far below the limits for localized exposure of the head, as defined by the International Commission for Non-Ionizing Radiation Protection. Particularly the induced SAR inside the eye was found to be substantially (orders of magnitudes for typical reader antenna currents in the order of 1 A turn) below values which have been reported to be critical with respect to thermally induced adverse health effects in eye tissues. PMID:24002053

  17. Analysis of in situ electric field and specific absorption rate in human models for wireless power transfer system with induction coupling.

    PubMed

    Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; Onishi, Teruo

    2014-07-21

    This study investigates the specific absorption rate (SAR) and the in situ electric field in anatomically based human models for the magnetic field from an inductive wireless power transfer system developed on the basis of the specifications of the wireless power consortium. The transfer system consists of two induction coils covered by magnetic sheets. Both the waiting and charging conditions are considered. The transfer frequency considered in this study is 140 kHz, which is within the range where the magneto-quasi-static approximation is valid. The SAR and in situ electric field in the chest and arm of the models are calculated by numerically solving the scalar potential finite difference equation. The electromagnetic modelling of the coils in the wireless power transfer system is verified by comparing the computed and measured magnetic field distributions. The results indicate that the peak value of the SAR averaged over a 10 g of tissue and that of the in situ electric field are 72 nW kg(-1) and 91 mV m(-1) for a transmitted power of 1 W, Consequently, the maximum allowable transmitted powers satisfying the exposure limits of the SAR (2 W kg(-1)) and the in situ electric field (18.9 V m(-1)) are found to be 28 MW and 43 kW. The computational results show that the in situ electric field in the chest is the most restrictive factor when compliance with the wireless power transfer system is evaluated according to international guidelines. PMID:24936747

  18. Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T

    PubMed Central

    Beqiri, Arian; Price, Anthony N.; Teixeira, Jose Nuno; Hand, Jeffrey W.; Hajnal, Joseph V.

    2015-01-01

    MRI is finding increased clinical use in neonatal populations; the extent to which electromagnetic models used for quantification of specific absorption rate (SAR) by commercial MRI scanners accurately reflect this alternative scenario is unclear. This study investigates how SAR predictions relating to adults can be related to neonates under differing conditions when imaged using 1.5 T and 3 T MRI scanners. Electromagnetic simulations were produced in neonatal subjects of different sizes and positions within a generic MRI body transmit device operating at both 64 MHz and 128 MHz, corresponding to 1.5 T and 3 T MRI scanners, respectively. An adult model was also simulated, as was a spherical salt‐water phantom, which was also used in a calorimetry experiment. The SAR in neonatal subjects was found to be less than that experienced in an adult in all scenarios; however, the overestimation factor was variable. For example a 3 T body scan resulting in local 10 g SAR of 10.1 W kg−1 in an adult would deposit 2.6 W kg−1 in a neonate: an approximately fourfold difference. The SAR experienced by neonatal subjects undergoing MRI is lower than that in adults in equivalent situations. If the safety of such procedures is assessed using adult‐appropriate models then the result is a conservative estimate. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd. PMID:25594939

  19. Numerical analysis of specific absorption rate in the human head due to a 13.56 MHz RFID-based intra-ocular pressure measurement system

    NASA Astrophysics Data System (ADS)

    Hirtl, Rene; Schmid, Gernot

    2013-09-01

    A modern wireless intra-ocular pressure monitoring system, based on 13.56 MHz inductively coupled data transmission, was dosimetrically analyzed with respect to the specific absorption rate (SAR) induced inside the head and the eye due to the electromagnetic field exposure caused by the reader antenna of the transmission system. The analysis was based on numerical finite difference time domain computations using a high resolution anatomical eye model integrated in a modern commercially available anatomical model of a male head. Three different reader antenna configurations, a 7-turn elliptic (30 mm × 50 mm) antenna at 12 mm distance from the eye, a flexible circular antenna (60 mm diameter, 8 turns on 2 mm substrate) directly attached to the skin, and a circular 7-turn antenna (30 mm diameter at 12 mm distance to the eye) were analyzed, respectively. Possible influences of the eye-lid status (closed or opened) and the transponder antenna contained in a contact lens directly attached to the eye were taken into account. The results clearly demonstrated that for typical reader antenna currents required for proper data transmission, the SAR values remain far below the limits for localized exposure of the head, as defined by the International Commission for Non-Ionizing Radiation Protection. Particularly the induced SAR inside the eye was found to be substantially (orders of magnitudes for typical reader antenna currents in the order of 1 A turn) below values which have been reported to be critical with respect to thermally induced adverse health effects in eye tissues.

  20. Specific absorption rate levels measured in a phantom head exposed to radio frequency transmissions from analog hand-held mobile phones

    SciTech Connect

    Anderson, V.; Joyner, K.H.

    1995-05-01

    Electric fields (E-fields) induced within a phantom head from exposure to three different advanced mobile phone system (AMPS) hand-held telephones were measured using an implantable E-Field probe. Measurements were taken in the eye nearest the phone and along a lateral scan through the brain from its center to the side nearest the phone. During measurement, the phones were positioned alongside the phantom head as in typical use and were configured to transmit at maximum power (600 mW nominal). The specific absorption rate (SAR) was calculated from the in situ E-field measurements, which varied significantly between phone models and antenna configuration. The SARs induced in the eye ranged from 0.007 to 0.21 W/kg. Metal-framed spectacles enhanced SAR levels in the eye by 9--29%. In the brain, maximum levels were recorded at the measurement point closest to the phone and ranged from 0.12 to 0.83 W/kg. These SARs are below peak spatial limits recommended in the US and Australian national standards and the IRPA guidelines for safe exposure to radio frequency (RF) electromagnetic fields. Furthermore, a detailed thermal analysis of the eye indicated only a 0.022 C maximum steady-state temperature rise in the eye from a uniform SAR loading of 0.21 W/kg. A more approximate thermal analysis in the brain also indicated only a small maximum temperature rise of 0.034 C for a local SAR loading of 0.83 W/kg.

  1. Analysis of in situ electric field and specific absorption rate in human models for wireless power transfer system with induction coupling.

    PubMed

    Sunohara, Tetsu; Hirata, Akimasa; Laakso, Ilkka; Onishi, Teruo

    2014-07-21

    This study investigates the specific absorption rate (SAR) and the in situ electric field in anatomically based human models for the magnetic field from an inductive wireless power transfer system developed on the basis of the specifications of the wireless power consortium. The transfer system consists of two induction coils covered by magnetic sheets. Both the waiting and charging conditions are considered. The transfer frequency considered in this study is 140 kHz, which is within the range where the magneto-quasi-static approximation is valid. The SAR and in situ electric field in the chest and arm of the models are calculated by numerically solving the scalar potential finite difference equation. The electromagnetic modelling of the coils in the wireless power transfer system is verified by comparing the computed and measured magnetic field distributions. The results indicate that the peak value of the SAR averaged over a 10 g of tissue and that of the in situ electric field are 72 nW kg(-1) and 91 mV m(-1) for a transmitted power of 1 W, Consequently, the maximum allowable transmitted powers satisfying the exposure limits of the SAR (2 W kg(-1)) and the in situ electric field (18.9 V m(-1)) are found to be 28 MW and 43 kW. The computational results show that the in situ electric field in the chest is the most restrictive factor when compliance with the wireless power transfer system is evaluated according to international guidelines.

  2. The relationship between specific absorption rate and temperature elevation in anatomically based human body models for plane wave exposure from 30 MHz to 6 GHz.

    PubMed

    Hirata, Akimasa; Laakso, Ilkka; Oizumi, Takuya; Hanatani, Ryuto; Chan, Kwok Hung; Wiart, Joe

    2013-02-21

    According to the international safety guidelines/standard, the whole-body-averaged specific absorption rate (Poljak et al 2003 IEEE Trans. Electromagn. Compat. 45 141-5) and the peak spatial average SAR are used as metrics for human protection from whole-body and localized exposures, respectively. The IEEE standard (IEEE 2006 IEEE C95.1) indicates that the upper boundary frequency, over which the whole-body-averaged SAR is deemed to be the basic restriction, has been reduced from 6 to 3 GHz, because radio-wave energy is absorbed around the body surface when the frequency is increased. However, no quantitative discussion has been provided to support this description especially from the standpoint of temperature elevation. It is of interest to investigate the maximum temperature elevation in addition to the core temperature even for a whole-body exposure. In the present study, using anatomically based human models, we computed the SAR and the temperature elevation for a plane-wave exposure from 30 MHz to 6 GHz, taking into account the thermoregulatory response. As the primary result, we found that the ratio of the core temperature elevation to the whole-body-averaged SAR is almost frequency independent for frequencies below a few gigahertz; the ratio decreases above this frequency. At frequencies higher than a few gigahertz, core temperature elevation for the same whole-body averaged SAR becomes lower due to heat convection from the skin to air. This lower core temperature elevation is attributable to skin temperature elevation caused by the power absorption around the body surface. Then, core temperature elevation even for whole-body averaged SAR of 4 W kg(-1) with the duration of 1 h was at most 0.8 °C, which is smaller than a threshold considered in the safety guidelines/standard. Further, the peak 10 g averaged SAR is correlated with the maximum body temperature elevations without extremities and pinna over the frequencies considered. These findings

  3. Toward Online Adaptive Hyperthermia Treatment Planning: Correlation Between Measured and Simulated Specific Absorption Rate Changes Caused by Phase Steering in Patients

    SciTech Connect

    Kok, H. Petra; Ciampa, Silvia; Kroon-Oldenhof, Rianne de; Steggerda-Carvalho, Eva J.; Stam, Gerard van; Zum Vörde Sive Vörding, Paul J.; Stalpers, Lukas J.A.; Geijsen, Elisabeth D.; Bardati, Fernando; Bel, Arjan; Crezee, Johannes

    2014-10-01

    Purpose: Hyperthermia is the clinical application of heat, in which tumor temperatures are raised to 40°C to 45°C. This proven radiation and chemosensitizer significantly improves clinical outcome for several tumor sites. Earlier studies of the use of pre-treatment planning for hyperthermia showed good qualitative but disappointing quantitative reliability. The purpose of this study was to investigate whether hyperthermia treatment planning (HTP) can be used more reliably for online adaptive treatment planning during locoregional hyperthermia treatments. Methods and Materials: This study included 78 treatment sessions for 15 patients with non-muscle-invasive bladder cancer. At the start of treatments, temperature rise measurements were performed with 3 different antenna settings optimized for each patient, from which the absorbed power (specific absorption rate [SAR]) was derived. HTP was performed based on a computed tomography (CT) scan in treatment position with the bladder catheter in situ. The SAR along the thermocouple tracks was extracted from the simulated SAR distributions. Correlations between measured and simulated (average) SAR values were determined. To evaluate phase steering, correlations between the changes in simulated and measured SAR values averaged over the thermocouple probe were determined for all 3 combinations of antenna settings. Results: For 42% of the individual treatment sessions, the correlation coefficient between measured and simulated SAR profiles was higher than 0.5, whereas 58% showed a weak correlation (R of <0.5). The overall correlation coefficient between measured and simulated average SAR was weak (R=0.31; P<.001). The measured and simulated changes in average SAR after adapting antenna settings correlated much better (R=0.70; P<.001). The ratio between the measured and simulated quotients of maximum and average SARs was 1.03 ± 0.26 (mean ± SD), indicating that HTP can also correctly predict the relative amplitude of

  4. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  5. Aspirin absorption rates and platelet inhibition times with 325-mg buffered aspirin tablets (chewed or swallowed intact) and with buffered aspirin solution.

    PubMed

    Feldman, M; Cryer, B

    1999-08-15

    Large clinical trials such as the second International Study of Infarct Survival routinely gave patients with myocardial infarction a chewed aspirin, yet there are no data to show whether chewing of aspirin is better, or worse, than swallowing a whole tablet. We performed a randomized, placebo-controlled study to determine whether chewing aspirin or administering it in solution accelerates its absorption and antiplatelet activity. On separate days, 12 fasting volunteers ingested 325 mg of buffered aspirin, either by chewing a tablet for 30 seconds before swallowing it with 4 ounces of water, swallowing a whole tablet with 4 ounces of water, or drinking 4 ounces of Alka Seltzer. Frequent blood samples were obtained for serum aspirin, salicylate, and thromboxane B2 (TxB2) concentrations. With all formulations of aspirin, serum TxB2 decreased 50% when the plasma aspirin concentration reached approximately 1,000 ng/ml. A 50% and 90% decrease in serum TxB2 occurred more quickly after chewing a tablet than after a tablet was swallowed whole. For example, the t 50% for serum TxB2 inhibition was 5.0 +/- 0.6 minutes with the chewed tablet versus 12.0 +/- 2.3 minutes when the tablet was swallowed (p = 0.01). A 50% decrease in serum TxB2 occurred 7.6 +/- 1.2 minutes after Alka Seltzer solution (p = 0.04 vs chewing a tablet; p = 0.13 vs swallowing a whole tablet). Chewing an aspirin tablet is the most effective way of accelerating absorption of aspirin into the blood and shortening the time required for an antiplatelet effect. PMID:10468077

  6. Growth of (1 1 1) and (2 0 0) orientation cubic MgZnO thin films under different oxygen flow rate by PLD method and its difference in element composition and optical absorption characteristics

    SciTech Connect

    Han, S.; Shao, Y.K.; Lu, Y.M. Cao, P.J.; Liu, W.J.; Zeng, Y.X.; Jia, F.; Zhu, D.L.

    2015-04-15

    Under different migration energy of reactive Mg, Zn and O atoms from MgZnO target at different oxygen flow rate, (2 0 0) and (1 1 1) orientations MgZnO thin films with cubic structure were fabricated on fused quartz substrate by PLD method. And MgZnO thin film possesses relatively higher Zn composition and lower Mg composition when deposited more along (1 1 1) orientation. The band gap and UV absorption characteristics of MgZnO thin film do not change completely in accordance with the Mg/Zn atom ratio of MgZnO thin films deposited at different oxygen flow rate, but influenced more by the ratio between Mg and Zn atoms that combined with O atoms in MgZnO crystal lattice and the grain boundary density of MgZnO thin films deposited at different oxygen flow rate.

  7. Does absorption of ultraviolet B by stratospheric ozone and urban aerosols influence colon and breast cancer mortality rates? Contributions from NASA and NOAA data

    NASA Astrophysics Data System (ADS)

    Gorham, Edward D.; Garland, Frank C.; Mohr, Sharif B.; Grant, William B.; Garland, Cedric F.

    2005-08-01

    Although most ultraviolet B (UVB) radiation is absorbed by stratospheric ozone, dense anthropogenic sulfate aerosols in the troposphere may further attenuate UVB in some regions. Mortality rates from colon and breast cancer tend to be much higher in areas with low levels of UVB radiation. These high rates may be due in part to inadequate cutaneous photosynthesis of vitamin D. Satellite data on atmospheric aerosols, stratospheric ozone, and cloud cover were obtained from the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA). These data were combined with age-adjusted mortality rates from 175 countries reporting to the World Health Organization. Regression was used to assess the relationship of stratospheric ozone thickness, aerosol optical depth, cloud cover, solar UVB irradiance at the top of the atmosphere, average skin exposure, and a dietary factor with colon and breast cancer mortality rates. Solar UVB irradiance at the top of the atmosphere, total cloud cover, and atmospheric aerosols had the strongest associations with mortality rates, apart from a strong influence of diet. Since 95% of circulating vitamin D is derived from current or stored products of photosynthesis, which may be nonexistent or minimal much of the year above 37°N or below 37°S, attenuation of UVB by atmospheric aerosols and clouds may have a greater than expected adverse effect on human health.

  8. Justification of Drug Product Dissolution Rate and Drug Substance Particle Size Specifications Based on Absorption PBPK Modeling for Lesinurad Immediate Release Tablets.

    PubMed

    Pepin, Xavier J H; Flanagan, Talia R; Holt, David J; Eidelman, Anna; Treacy, Don; Rowlings, Colin E

    2016-09-01

    In silico absorption modeling has been performed, to assess the impact of in vitro dissolution on in vivo performance for ZURAMPIC (lesinurad) tablets. The dissolution profiles of lesinurad tablets generated using the quality control method were used as an input to a GastroPlus model to estimate in vivo dissolution in the various parts of the GI tract and predict human exposure. A model was set up, which accounts for differences of dosage form transit, dissolution, local pH in the GI tract, and fluid volumes available for dissolution. The predictive ability of the model was demonstrated by confirming that it can reproduce the Cmax observed for independent clinical trial. The model also indicated that drug product batches that pass the proposed dissolution specification of Q = 80% in 30 min are anticipated to be bioequivalent to the clinical reference batch. To further explore the dissolution space, additional simulations were performed using a theoretical dissolution profile below the proposed specification. The GastroPlus modeling indicates that such a batch will also be bioequivalent to standard clinical batches despite having a dissolution profile, which would fail the proposed dissolution specification of Q = 80% in 30 min. This demonstrates that the proposed dissolution specification sits comfortably within a region of dissolution performance where bioequivalence is anticipated and is not near an edge of failure for dissolution, providing additional confidence to the proposed specifications. Finally, simulations were performed using a virtual drug substance batch with a particle size distribution at the limit of the proposed specification for particle size. Based on these simulations, such a batch is also anticipated to be bioequivalent to clinical reference, demonstrating that the proposed specification limits for particle size distribution would give products bioequivalent to the pivotal clinical batches. PMID:27438964

  9. Justification of Drug Product Dissolution Rate and Drug Substance Particle Size Specifications Based on Absorption PBPK Modeling for Lesinurad Immediate Release Tablets.

    PubMed

    Pepin, Xavier J H; Flanagan, Talia R; Holt, David J; Eidelman, Anna; Treacy, Don; Rowlings, Colin E

    2016-09-01

    In silico absorption modeling has been performed, to assess the impact of in vitro dissolution on in vivo performance for ZURAMPIC (lesinurad) tablets. The dissolution profiles of lesinurad tablets generated using the quality control method were used as an input to a GastroPlus model to estimate in vivo dissolution in the various parts of the GI tract and predict human exposure. A model was set up, which accounts for differences of dosage form transit, dissolution, local pH in the GI tract, and fluid volumes available for dissolution. The predictive ability of the model was demonstrated by confirming that it can reproduce the Cmax observed for independent clinical trial. The model also indicated that drug product batches that pass the proposed dissolution specification of Q = 80% in 30 min are anticipated to be bioequivalent to the clinical reference batch. To further explore the dissolution space, additional simulations were performed using a theoretical dissolution profile below the proposed specification. The GastroPlus modeling indicates that such a batch will also be bioequivalent to standard clinical batches despite having a dissolution profile, which would fail the proposed dissolution specification of Q = 80% in 30 min. This demonstrates that the proposed dissolution specification sits comfortably within a region of dissolution performance where bioequivalence is anticipated and is not near an edge of failure for dissolution, providing additional confidence to the proposed specifications. Finally, simulations were performed using a virtual drug substance batch with a particle size distribution at the limit of the proposed specification for particle size. Based on these simulations, such a batch is also anticipated to be bioequivalent to clinical reference, demonstrating that the proposed specification limits for particle size distribution would give products bioequivalent to the pivotal clinical batches.

  10. THE ABSORPTION OF ADRENALIN

    PubMed Central

    Lyon, D. Murray

    1923-01-01

    1. Adrenalin solution given subcutaneously is usually rapidly absorbed, probably by lymphatic channels. 2. The speed of this process may be influenced by the circulation rate. 3. The relative amounts of adrenalin at any moment unabsorbed at the site of inoculation, carried in the circulating fluids, and taken up by the reacting tissues can be calculated from figures extracted from the curve of the blood pressure changes. The relative rates of transference of adrenalin into the blood and from the circulation into the tissues can also be estimated. 4. When absorption takes place rapidly a large quantity of the drug comes into action at once and the maximum occurs early, the curve of blood pressure reaches a considerable height, and subsides quickly. When absorption is slow the apex appears later and does not reach so high a level. 5. The response to adrenalin bears a logarithmic relationship to the dose employed and a method of allowing for this is indicated. PMID:19868816

  11. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  12. Light absorption measurements: new techniques.

    PubMed

    Hänel, G; Busen, R; Hillenbrand, C; Schloss, R

    1982-02-01

    A new radiometer is described which simplifies measurement of the radiation supply of solar wavelengths. Two methods of measuring the radiant energy absorbed by aerosol particles are described: A photometric technique is used for particles collected on filters, and a calorimetric technique is used for in situ measurements. Data collected with the radiometer and the light absorption techniques yield the heating rate of the atmosphere due to light absorption by the particles. Sample measurements show substantial atmospheric temperature increases due to absorption, especially in industrial regions.

  13. Photochemical properties of trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl═CHCF3): OH reaction rate constant, UV and IR absorption spectra, global warming potential, and ozone depletion potential.

    PubMed

    Orkin, Vladimir L; Martynova, Larissa E; Kurylo, Michael J

    2014-07-17

    Measurements of the rate constant for the gas-phase reactions of OH radicals with trans-1-chloro-3,3,3-trifluoropropene (trans-CHCl═CHCF3) were performed using a flash photolysis resonance-fluorescence technique over the temperature range 220-370 K. The reaction rate constant exhibits a noticeable curvature of the temperature dependence in the Arrhenius plot, which can be represented by the following expression: kt-CFP (220-370 K) = 1.025 × 10(-13) × (T/298)(2.29) exp(+384/T) cm(3 )molecule(-1) s(-1). The room-temperature rate constant was determined to be kt-CFP (298 K) = (3.29 ± 0.10) × 10(-13) cm(3) molecule(-1) s(-1), where the uncertainty includes both two standard errors (statistical) and the estimated systematic error. For atmospheric modeling purposes, the rate constant below room temperature can be represented by the following expression: kt-CFP (220-298 K) = (7.20 ± 0.46) × 10(-13) exp[-(237 ± 16)/T] cm(3) molecule(-1) s(-1). There was no difference observed between the rate constants determined at 4 kPa (30 Torr) and 40 kPa (300 Torr) at both 298 and 370 K. The UV and IR absorption cross sections of this compound were measured at room temperature. The atmospheric lifetime, global warming potential, and ozone depletion potential of trans-CHCl═CHCF3 were estimated. PMID:24955760

  14. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    Eberle, b

    2004-01-28

    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  15. Hydroxyl radical reaction rate coefficients as a function of temperature and IR absorption cross sections for CF3CH=CH2 (HFO-1243zf), potential replacement of CF3CH2F (HFC-134a).

    PubMed

    González, Sergio; Jiménez, Elena; Ballesteros, Bernabé; Martínez, Ernesto; Albaladejo, José

    2015-04-01

    CF3CH=CH2 (hydrofluoroolefin, HFO-1243zf) is a potential replacement of high global-warming potential (GWP) hydrofluorocarbon (HFC-134a, CF3CFH2). Both the atmospheric lifetime and the radiative efficiency of HFO-1243zf are parameters needed for estimating the GWP of this species. Therefore, the aim of this work is (i) to estimate the atmospheric lifetime of HFO-1243zf from the reported OH rate coefficients, k OH, determined under tropospheric conditions and (ii) to calculate its radiative efficiency from the reported IR absorption cross sections. The OH rate coefficient at 298 K also allows the estimation of the photochemical ozone creation potential (ε(POCP)). The pulsed laser photolysis coupled to a laser-induced fluorescence technique was used to determine k OH for the reaction of OH radicals with HFO-1243zf as a function of pressure (50-650 Torr of He) and temperature (263-358 K). Gas-phase IR spectra of HFO-1243zf were recorded at room temperature using a Fourier transform IR spectrometer between 500 and 4,000 cm(-1). At all temperatures, k OH did not depend on bath gas concentration (i.e., on the total pressure between 50 and 650 Torr of He). A slight but noticeable T dependence of k OH was observed in the temperature range investigated. The observed behavior is well described by the following Arrhenius expression: k OH(T) = (7.65 ± 0.26) × 10(-13) exp [(165 ± 10) / T] cm(3) molecule(-1) s(-1). Negligible IR absorption of HFO-1243zf was observed at wavenumbers greater than 1,700 cm(-1). Therefore, IR absorption cross sections, [Formula: see text], were determined in the 500-1,700 cm(-1) range. Integrated [Formula: see text] were determined between 650 and 1,800 cm(-1) for comparison purposes. The main diurnal removal pathway for HFO-1243zf is the reaction with OH radicals, which accounts for 64% of the overall loss by homogeneous reactions at 298 K. Globally, the lifetime due to OH reaction (τ OH) was estimated to be 8.7 days under

  16. Hydroxyl radical reaction rate coefficients as a function of temperature and IR absorption cross sections for CF3CH=CH2 (HFO-1243zf), potential replacement of CF3CH2F (HFC-134a).

    PubMed

    González, Sergio; Jiménez, Elena; Ballesteros, Bernabé; Martínez, Ernesto; Albaladejo, José

    2015-04-01

    CF3CH=CH2 (hydrofluoroolefin, HFO-1243zf) is a potential replacement of high global-warming potential (GWP) hydrofluorocarbon (HFC-134a, CF3CFH2). Both the atmospheric lifetime and the radiative efficiency of HFO-1243zf are parameters needed for estimating the GWP of this species. Therefore, the aim of this work is (i) to estimate the atmospheric lifetime of HFO-1243zf from the reported OH rate coefficients, k OH, determined under tropospheric conditions and (ii) to calculate its radiative efficiency from the reported IR absorption cross sections. The OH rate coefficient at 298 K also allows the estimation of the photochemical ozone creation potential (ε(POCP)). The pulsed laser photolysis coupled to a laser-induced fluorescence technique was used to determine k OH for the reaction of OH radicals with HFO-1243zf as a function of pressure (50-650 Torr of He) and temperature (263-358 K). Gas-phase IR spectra of HFO-1243zf were recorded at room temperature using a Fourier transform IR spectrometer between 500 and 4,000 cm(-1). At all temperatures, k OH did not depend on bath gas concentration (i.e., on the total pressure between 50 and 650 Torr of He). A slight but noticeable T dependence of k OH was observed in the temperature range investigated. The observed behavior is well described by the following Arrhenius expression: k OH(T) = (7.65 ± 0.26) × 10(-13) exp [(165 ± 10) / T] cm(3) molecule(-1) s(-1). Negligible IR absorption of HFO-1243zf was observed at wavenumbers greater than 1,700 cm(-1). Therefore, IR absorption cross sections, [Formula: see text], were determined in the 500-1,700 cm(-1) range. Integrated [Formula: see text] were determined between 650 and 1,800 cm(-1) for comparison purposes. The main diurnal removal pathway for HFO-1243zf is the reaction with OH radicals, which accounts for 64% of the overall loss by homogeneous reactions at 298 K. Globally, the lifetime due to OH reaction (τ OH) was estimated to be 8.7 days under

  17. Determination of the rate constants of molecular processes regulating the level of induced absorption in a laser based on an aqueous-micellar solution of rhodamine 6G with lamp pumping

    SciTech Connect

    Levin, M.B.; Snegov, M.I.; Cherkasov, A.S.

    1987-03-01

    A method of determining the average lifetime tau of the products responsible for inverse induced absorption in aqueous--micellar solutions of rhodamine 6G (R6G) on lamp pumping based on a comparison of threshold intensities of excitation (W/sub th/) in the resonators of a laser with a different Q is proposed. Using the value of tau found (0.2 ..mu..sec) and experimental data on the change in W/sub th/ with the concentration of cyclooctatetraene (COT) added to the solution the rate constant of quenching of the absorbing products by COT molecules (K/sub q/ = 2.6 x 10/sup 7/ M/sup -1/sec/sup -1/) was determined. In the assumption that the absorbing products are triplet dye molecules, the value of the rate constant of interconversion (K/sub 32/) of R6G into an aqueous--micellar solution (K/sub 32/ = 1.3 x 10/sup 7/ sec/sup -1/) was determined. A comparison was made of the values of the constants found with the corresponding values known from the literature.

  18. An anatomically realistic whole-body pregnant-woman model and specific absorption rates for pregnant-woman exposure to electromagnetic plane waves from 10 MHz to 2 GHz

    NASA Astrophysics Data System (ADS)

    Nagaoka, Tomoaki; Togashi, Toshihiro; Saito, Kazuyuki; Takahashi, Masaharu; Ito, Koichi; Watanabe, Soichi

    2007-11-01

    The numerical dosimetry of pregnant women is an important issue in electromagnetic-field safety. However, an anatomically realistic whole-body pregnant-woman model for electromagnetic dosimetry has not been developed. Therefore, we have developed a high-resolution whole-body model of pregnant women. A new fetus model including inherent tissues of pregnant women was constructed on the basis of abdominal magnetic resonance imaging data of a 26-week-pregnant woman. The whole-body pregnant-woman model was developed by combining the fetus model and a nonpregnant-woman model that was developed previously. The developed model consists of about 7 million cubical voxels of 2 mm size and is segmented into 56 tissues and organs. This pregnant-woman model is the first completely anatomically realistic voxel model that includes a realistic fetus model and enables a numerical simulation of electromagnetic dosimetry up to the gigahertz band. In this paper, we also present the basic specific absorption rate characteristics of the pregnant-woman model exposed to vertically and horizontally polarized electromagnetic waves from 10 MHz to 2 GHz.

  19. Absorption heat pumps

    NASA Astrophysics Data System (ADS)

    Huhtinen, M.; Heikkilae, M.; Andersson, R.

    1987-03-01

    The aim of the study was to analyze the technical and economic feasibility of absorption heat pumps in Finland. The work was done as a case study: the technical and economic analyses have been carried out for six different cases, where in each the suitable size and type of the heat pump plant and the auxiliary components and connections were specified. The study also detailed the costs concerning the procurement, installation and test runs of the machinery, as well as the savings in energy costs incurred by the introduction of the plant. Conclusions were drawn of the economic viability of the applications studied. The following cases were analyzed: heat recovery from flue gases and productin of district heat in plants using peat, natural gas, and municipal wastes as a fuel. Heat recovery in the pulp and paper industry for the upgrading of pressure of secondary steam and for the heating of white liquor and combustion and drying the air. Heat recovery in a peat-fulled heat and power plant from flue gases that have been used for the drying of peat. According to the study, the absorption heat pump suits best to the production of district heat, when the heat source is the primary energy is steam produced by the boiler. Included in the flue as condensing is the purification of flue gases. Accordingly, benefit is gained on two levels in thick applications. In heat and power plants the use of absorption heat pumps is less economical, due to the fact that the steam used by the pump reduces the production of electricity, which is rated clearly higher than heat.

  20. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1absorption (FW20) lies in the range 63 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1

  1. Time-dependent oral absorption models

    NASA Technical Reports Server (NTRS)

    Higaki, K.; Yamashita, S.; Amidon, G. L.

    2001-01-01

    The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

  2. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

  3. Liver imaging at 3.0 T: diffusion-induced black-blood echo-planar imaging with large anatomic volumetric coverage as an alternative for specific absorption rate-intensive echo-train spin-echo sequences: feasibility study.

    PubMed

    van den Bos, Indra C; Hussain, Shahid M; Krestin, Gabriel P; Wielopolski, Piotr A

    2008-07-01

    Institutional Review Board approval and signed informed consent were obtained by all participants for an ongoing sequence optimization project at 3.0 T. The purpose of this study was to evaluate breath-hold diffusion-induced black-blood echo-planar imaging (BBEPI) as a potential alternative for specific absorption rate (SAR)-intensive spin-echo sequences, in particular, the fast spin-echo (FSE) sequences, at 3.0 T. Fourteen healthy volunteers (seven men, seven women; mean age +/- standard deviation, 32.7 years +/- 6.8) were imaged for this purpose. Liver coverage (20 cm, z-axis) was always performed in one 25-second breath hold. Imaging parameters were varied interactively with regard to echo time, diffusion b value, and voxel size. Images were evaluated and compared with fat-suppressed T2-weighted FSE images for image quality, liver delineation, geometric distortions, fat suppression, suppression of the blood signal, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). An optimized short- (25 msec) and long-echo (80 msec) BBEPI provided full anatomic, single breath-hold liver coverage (100 and 50 sections, respectively), with resulting voxel sizes of 3.3 x 2.7 x 2.0 mm and 3.3 x 2.7 x 4.0 mm, respectively. Repetition time was 6300 msec, matrix size was 160 x 192, and an acceleration factor of 2.00 was used. b Values of more than 20 sec/mm(2) showed better suppression of the blood signal but b values of 10 sec/mm(2) provided improved volume coverage and signal consistency. Compared with fat-suppressed T2-weighted FSE, the optimized BBEPI sequence provided (a) comparable image quality and liver delineation, (b) acceptable geometric distortions, (c) improved suppression of fat and blood signals, and (d) high CNR and SNR. BBEPI is feasible for fast, low-SAR, thin-section morphologic imaging of the entire liver in a single breath hold at 3.0 T. PMID:18566178

  4. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  5. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

    We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

  6. [Microwave absorption by magnetic nanoparticles in organisms].

    PubMed

    Bingi, V N

    2011-01-01

    An estimate of the rate of absorption of the electromagnetic microwaves by magnetic nanoparticles in organisms is presented. The absorption takes place due to the energy dissipation at the ferromagnetic resonance. Based on the known solution of the Landau-Lifshitz equation, the imaginary part of the complex magnetic susceptibility is evaluated that gives the absorption rate. It is shown that even in the conditions of thermal isolation of the particles, their temperature growth would be insignificant at absorption of the emission with the energy flux density of the order of 1 mW/cm2, and the given mechanism is unrelated to the observable effects of low-intensity microwaves. PMID:22279759

  7. Intestinal Water Absorption Varies with Expected Dietary Water Load among Bats but Does Not Drive Paracellular Nutrient Absorption.

    PubMed

    Price, Edwin R; Brun, Antonio; Gontero-Fourcade, Manuel; Fernández-Marinone, Guido; Cruz-Neto, Ariovaldo P; Karasov, William H; Caviedes-Vidal, Enrique

    2015-01-01

    Rapid absorption and elimination of dietary water should be particularly important to flying species and were predicted to vary with the water content of the natural diet. Additionally, high water absorption capacity was predicted to be associated with high paracellular nutrient absorption due to solvent drag. We compared the water absorption rates of sanguivorous, nectarivorous, frugivorous, and insectivorous bats in intestinal luminal perfusions. High water absorption rates were associated with high expected dietary water load but were not highly correlated with previously measured rates of (paracellular) arabinose clearance. In conjunction with these tests, we measured water absorption and the paracellular absorption of nutrients in the intestine and stomach of vampire bats using luminal perfusions to test the hypothesis that the unique elongated vampire stomach is a critical site of water absorption. Vampire bats' gastric water absorption was high compared to mice but not compared to their intestines. We therefore conclude that (1) dietary water content has influenced the evolution of intestinal water absorption capacity in bats, (2) solvent drag is not the only driver of paracellular nutrient absorption, and (3) the vampire stomach is a capable but not critical location for water absorption.

  8. Intestinal Water Absorption Varies with Expected Dietary Water Load among Bats but Does Not Drive Paracellular Nutrient Absorption.

    PubMed

    Price, Edwin R; Brun, Antonio; Gontero-Fourcade, Manuel; Fernández-Marinone, Guido; Cruz-Neto, Ariovaldo P; Karasov, William H; Caviedes-Vidal, Enrique

    2015-01-01

    Rapid absorption and elimination of dietary water should be particularly important to flying species and were predicted to vary with the water content of the natural diet. Additionally, high water absorption capacity was predicted to be associated with high paracellular nutrient absorption due to solvent drag. We compared the water absorption rates of sanguivorous, nectarivorous, frugivorous, and insectivorous bats in intestinal luminal perfusions. High water absorption rates were associated with high expected dietary water load but were not highly correlated with previously measured rates of (paracellular) arabinose clearance. In conjunction with these tests, we measured water absorption and the paracellular absorption of nutrients in the intestine and stomach of vampire bats using luminal perfusions to test the hypothesis that the unique elongated vampire stomach is a critical site of water absorption. Vampire bats' gastric water absorption was high compared to mice but not compared to their intestines. We therefore conclude that (1) dietary water content has influenced the evolution of intestinal water absorption capacity in bats, (2) solvent drag is not the only driver of paracellular nutrient absorption, and (3) the vampire stomach is a capable but not critical location for water absorption. PMID:26658415

  9. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  10. Intestinal Folate Absorption

    PubMed Central

    Olinger, Edward J.; Bertino, Joseph R.; Binder, Henry J.

    1973-01-01

    These studies were designed to determine whether pteroylmonoglutamic acid (PGA) at physiologic concentrations is transported across the small intestine unaltered or is reduced and methylated to the circulating folate form (5-methyltetrahydrofolate [5-MeFH4]) during absorption. [3H]PGA was incubated in vitro on the mucosal side of rat jejunum. Of the folate transferred to the serosal side, the percent identified as 5-MeFH4 by DEAE-Sephadex chromtography was inversely related to the initial mucosa PGA concentration: at 7, 20, and 2,000 nM, 44%, 34%, and 2%, respectively, was converted to 5-MeFH4. In contrast, less than 4% of the folate transferred across ileal mucosa was 5-MeFH4 when the initial mucosa concentration was 20 nM. Specific activity of dihydrofolate (DHF) reductase, the enzyme responsible for converting PGA to tetrahydrofolic acid, was measured in villus homogenates and was significantly greater in the jejunum than in the ileum. 1,000 nM methotrexate (MTX), a DHF reductase inhibitor, markedly inhibited PGA conversion to 5-MeFH4 by the jejunum. Studies of transmural flux, initial rate of mucosal entry (influx) and mucosal accumulation (uptake) of folate were also performed. Although MTX did not alter the influx of PGA, MTX decreased jejunal mucosal uptake but increased transmural movement. Transmural folate movement across ileal mucosa was greater than across jejunal mucosa although mucosal uptake was greater in the jejunum than in the ileum. These results could explain previous studies which have failed to identify conversion of PGA to 5-MeFH4 when intestinal preparations have been exposed to higher and less physiologic concentrations of PGA. Further, these studies suggest that 5-MeFH4 may be retained by the jejunal mucosa. PMID:4727453

  11. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  12. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  13. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

    Hua, Duy H. (Inventor); Koo, Sung I. (Inventor); Noh, Sang K. (Inventor)

    2004-01-01

    A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

  14. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  15. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  16. Optical absorption measurement system

    DOEpatents

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  17. Nanofibrous membrane-based absorption refrigeration system

    SciTech Connect

    Isfahani, RN; Sampath, K; Moghaddam, S

    2013-12-01

    This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature, and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. Published by Elsevier Ltd.

  18. CARBON DIOXIDE SEPARATION BY PHASE ENHANCED GAS-LIQUID ABSORPTION

    SciTech Connect

    Liang Hu

    2004-09-30

    A new process called phase enhanced gas-liquid absorption has been developed in its early stage. It was found that adding another phase into the absorption system of gas/aqueous phase could enhance the absorption rate. A system with three phases was studied. In the system, gas phase was carbon dioxide. Two liquid phases were used. One was organic phase. Another was aqueous phase. By addition of organic phase into the absorption system of CO{sub 2}-aqueous phase, the absorption rate of CO{sub 2} was increased significantly. CO{sub 2} finally accumulated into aqueous phase. The experimental results proved that (1) Absorption rate of carbon dioxide was enhanced by adding organic phase into gas aqueous phase system; (2) Organic phase played the role of transportation of gas solute (CO{sub 2}). Carbon dioxide finally accumulated into aqueous phase.

  19. CARBON DIOXIDE SEPARATION BY PHASE ENHANCED GAS-LIQUID ABSORPTION

    SciTech Connect

    Liang Hu; Adeyinka A. Adeyiga

    2004-05-01

    A new process called phase enhanced gas-liquid absorption has been developed in its early stage. It was found that adding another phase into the absorption system of gas/aqueous phase could enhance the absorption rate. A system with three phases was studied. In the system, gas phase was carbon dioxide. Two liquid phases were used. One was organic phase. Another was aqueous phase. By addition of organic phase into the absorption system of CO{sub 2}-aqueous phase, the absorption rate of CO{sub 2} was increased significantly. CO{sub 2} finally accumulated into aqueous phase. The experimental results proved that (1) Absorption rate of carbon dioxide was enhanced by adding organic phase into gas aqueous phase system; (2) Organic phase played the role of transportation of gas solute (CO{sub 2}). Carbon dioxide finally accumulated into aqueous phase.

  20. Seven-effect absorption refrigeration

    DOEpatents

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

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  1. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  2. Monitoring of MOCVD reactants by UV absorption

    SciTech Connect

    Baucom, K.C.; Killeen, K.P.; Moffat, H.K.

    1995-07-01

    In this paper, we describe how UV absorption measurements can be used to measure the flow rates of metal organic chemical vapor deposition (MOCVD) reactants. This method utilizes the calculation of UV extinction coefficients by measuring the total pressure and absorbance in the neat reactant system. The development of this quantitative reactant flow rate monitor allows for the direct measurement of the efficiency of a reactant bubbler. We demonstrate bubbler efficiency results for TMGa, and then explain some discrepancies found in the TMAl system due to the monomer to dimer equilibrium. Also, the UV absorption spectra of metal organic and hydride MOCVD reactants over the wavelength range 185 to 400 nm are reported.

  3. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  4. High efficiency advanced absorption heat pump

    NASA Astrophysics Data System (ADS)

    Reid, E. A., Jr.

    1982-03-01

    A high efficiency absorption heat pump for the residential market is investigated. The performance targets established for this high efficiency absorption heat pump are a heating coefficient of performance of 1.5 and a cooling coefficient of performance of 0.8 at rating conditions, including parasitic electric power consumption. The resulting heat pump would have a space heating capacity of 68,000 BTU/hour, and a space cooling capacity of 36,000 BTU/hour at rating conditions. A very simplified schematic block diagram of the high efficiency absorption heat pump cycle is shown. High temperature, high pressure, refrigerant vapor is produced in the refrigerant generator and heat exchange system, is condensed to a liquid in the condenser, expanded to a low pressure vapor in the evaporator, and mixed with and reabsorbed into the weakened solution returned from the refrigerant generator and heat exchange system in the absorber.

  5. Lipids: Absorption and transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the hydrophobic nature of lipids, dietary fat is handled differently than protein or carbohydrate with respect with digestion and absorption. Dietary fats are broken down throughout the gastrointestinal system. A unique group of enzymes and cofactors allows this process to proceed in an eff...

  6. Absorption driven focus shift

    NASA Astrophysics Data System (ADS)

    Harrop, N.; Wolf, S.; Maerten, O.; Dudek, K.; Ballach, S.; Kramer, R.

    2016-03-01

    Modern high brilliance near infrared lasers have seen a tremendous growth in applications throughout the world. Increased productivity has been achieved by higher laser power and increased brilliance of lasers. Positive impacts on the performance and costs of parts are opposed to threats on process stability and quality, namely shift of focus position over time. A high initial process quality will be reduced by contamination of optics, eventually leading to a focus shift or even destruction of the optics. Focus analysis at full power of multi-kilowatt high brilliance lasers is a very demanding task because of high power densities in the spot and the high power load on optical elements. With the newly developed high power projection optics, the High-Power Micro-Spot Monitor High Brilliance (HP-MSM-HB) is able to measure focus diameter as low as 20 μm at power levels up to 10 kW at very low internal focus shift. A main driving factor behind thermally induced focus shift is the absorption level of the optical element. A newly developed measuring system is designed to determine the relative absorption level in reference to a gold standard. Test results presented show a direct correlation between absorption levels and focus shift. The ability to determine the absorption level of optical elements as well as their performance at full processing power before they are put to use, enables a high level of quality assurance for optics manufacturers and processing head manufacturers alike.

  7. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  8. Cholesterol Absorption and Metabolism.

    PubMed

    Howles, Philip N

    2016-01-01

    Inhibitors of cholesterol absorption have been sought for decades as a means to treat and prevent cardiovascular diseases (CVDs) associated with hypercholesterolemia. Ezetimibe is the one clear success story in this regard, and other compounds with similar efficacy continue to be sought. In the last decade, the laboratory mouse, with all its genetic power, has become the premier experimental model for discovering the mechanisms underlying cholesterol absorption and has become a critical tool for preclinical testing of potential pharmaceutical entities. This chapter briefly reviews the history of cholesterol absorption research and the various gene candidates that have come under consideration as drug targets. The most common and versatile method of measuring cholesterol absorption is described in detail along with important considerations when interpreting results, and an alternative method is also presented. In recent years, reverse cholesterol transport (RCT) has become an area of intense new interest for drug discovery since this process is now considered another key to reducing CVD risk. The ultimate measure of RCT is sterol excretion and a detailed description is given for measuring neutral and acidic fecal sterols and interpreting the results. PMID:27150091

  9. CHLORINE ABSORPTION IN S(IV) SOLUTIONS

    EPA Science Inventory

    The report gives results of measurements of the rate of Chlorine (Cl2) absorption into aqueous sulfite/bisulfite -- S(IV) -- solutions at ambient temperature using a highly characterized stirred-cell reactor. The reactor media were 0 to 10 mM S(IV) with pHs of 3.5-8.5. Experiment...

  10. Resonant absorption of p-modes by sunspots

    NASA Technical Reports Server (NTRS)

    Chitre, S. M.; Davila, Joseph M.

    1990-01-01

    Explanations for the observed p-mode absorption in sunspots are examined. It is demonstrated that any dissipative process like radiative, viscous, or resistive dissipation leads to the resonant absorption of acoustic waves incident on the sunspot tube, and that the resultant heating rate can be shown to be consistent with the observed absorption of the p-mode power impinging on an isolated inhomogeneously structured sunspot.

  11. Continuous Light Absorption Photometer (CLAP) Final Campaign Report

    SciTech Connect

    Jefferson, Anne

    2014-05-01

    The Continuous Light Absorption Photometer (CLAP) measures the aerosol absorption of radiation at three visible wavelengths; 461, 522, and 653 nanometers (nm). Data from this measurement is used in radiative forcing calculations, atmospheric heating rates, and as a prediction of the amount of equivalent black carbon in atmospheric aerosol and in models of aerosol semi-direct forcing. Aerosol absorption measurements are essential to modeling the energy balance of the atmosphere.

  12. [Intestinal absorption kinetics of flurbiprofen in rats].

    PubMed

    Peng, Jun-Jie; Lin, Cong-Cong; Li, Jiang; Zhu, Zhi-Hong; Yang, Xing-Gang; Pan, Wei-San

    2013-03-01

    To study the in situ intestinal absorption kinetics of flrubiprofen in rats, the absorption of flurbiprofen in small intestine (duodenum, jejunum and ileum) and colon of rats was investigated using in situ single-pass perfusion method and the drug content was measured by HPLC. The effects of drug concentration on the intestinal absorption were investigated. The K(a) and P(app) values of flurbiprofen in the small intestine and colon had no significant difference (P > 0.05). Drug concentration (4.0, 10.0 and 16.0 mg x L(-1)) had no significant influence on the K(a) values (P > 0.05). However, when concentration was 4.0 mg x L(-1) and 10.0 mg x L(-1), significant effect on the P(app) values (P < 0.05) was found, but significant effect on the P(app) values was not shown between 10.0 mg x L(-1) and 16.0 mg x L(-1) (P > 0.05). The K(a) and P(app) values of flurbiprofen on the perfusion flow rate had significant difference (P < 0.05). Flurbiprofen could be absorbed at all segments of the intestine in rats and had no special absorption window. The absorption of flurbiprofen complies with the facilitated diffusion in the general intestinal segments, and accompany with the cytopsistransport mechanism probably. The perfusion flow rate had significant effect on the K(a) and P(app).

  13. Measurements of the rate constant of HOsub2 + NOsub2 + Nsub2 --> HOsub2NOsub2 + Nsub2 using near-infrared wavelength-modulation spectroscopy and UV-visible absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Christensen, L. E.; Okumura, M.; Sander, S. P.; Friedl, R. R.; Miller, C. E.; Sloan, J. J.

    2004-01-01

    Rate coefficients for the reaction HO(sub 2)+ NO(sub 2) + N(sub 2) --> HO(sub 2)NO(sub 2) + N(sub 2) (reaction 1) were measured using simultaneous near-IR and UV spectroscopy from 220 to 298 K and from 45 to 200 Torr.

  14. The absorption of polymeric composites

    NASA Astrophysics Data System (ADS)

    Řídký, R.; Popovič, M.; Rolc, S.; Drdlová, M.; Krátký, J.

    2016-06-01

    An absorption capacity of soft, viscoelastic materials at high strain rates is important for wide range of practical applications. Nowadays there are many variants of numerical models suitable for this kind of analysis. The main difficulty is in selection of the most realistic numerical model and a correct setup of many unknown material constants. Cooperation between theoretical simulations and real testing is next crucial point in the investigation process. Standard open source material database offer material properties valid for strain rates less than 250 s-1. There are experiments suitable for analysis of material properties with strain rates close to 2000 s-1. The high strain-rate characteristics of a specific porous blast energy absorbing material measured by modified Split Hopkinson Pressure Bar apparatus is presented in this study. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. One of the possible solution leads to complex and frequency depended Young modulus of testing bars material. This testing technique was applied to materials composed of porous glass/ceramic filler and polymeric binder, with density of 125 - 300 kg/m3 and particle size in range of 50 µm - 2 mm. The achieved material model was verified in practical application of sandwich structure includes polymeric composites under a blast test.

  15. Intestinal absorption and biomagnification of organochlorines

    SciTech Connect

    Gobas, F.A.P.C. ); McCorquodale, J.R.; Haffner, G.D. )

    1993-03-01

    Dietary uptake rates of several organochlorines from diets with different lipid contents were measured in goldfish (Carassius auratus) to investigate the mechanism of intestinal absorption and biomagnification of organic chemical. The results suggest that intestinal absorption is predominantly controlled by chemical diffusion rather than lipid cotransport. Data for chemical uptake in human infants are presented to illustrate that biomagnification is caused by the digestion of food in the gastrointestinal tract. The findings are discussed in the context of two conflicting theories for the mechanism of biomagnification, and a mechanistic model is presented for the dietary uptake and biomagnification of organic chemicals in fish and mammals.

  16. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  17. Optimization of absorption air-conditioning for solar energy applications

    NASA Technical Reports Server (NTRS)

    Perry, E. H.

    1976-01-01

    Improved performance of solar cooling systems using the lithium bromide water absorption cycle is investigated. Included are computer simulations of a solar-cooled house, analyses and measurements of heat transfer rates in absorption system components, and design and fabrication of various system components. A survey of solar collector convection suppression methods is presented.

  18. Vaginal Absorption of Penicillin.

    PubMed

    Rock, J; Barker, R H; Bacon, W B

    1947-01-01

    Except during the last two months of pregnancy, penicillin is easily absorbed from cocoa butter suppositories in the vagina, ordinarily to give therapeutic blood levels for from 4 to 6 hours. Penicillin in the dosage used seems to have a good effect on vaginal infections. In nonpregnant women, during the ovulation phase, considered as including days 14 +/- 2 in the ordinary menstrual cycle of about 28 days, absorption seemed to be somewhat diminished. Higher levels were found in patients who were near the end of their menstrual cycles and in two patients who were menopausal. Patients who were very near term absorbed little or no penicillin, whereas patients 10 days post partum showed excellent absorption.

  19. Photothermal absorption correlation spectroscopy.

    PubMed

    Octeau, Vivien; Cognet, Laurent; Duchesne, Laurence; Lasne, David; Schaeffer, Nicolas; Fernig, David G; Lounis, Brahim

    2009-02-24

    Fluorescence correlation spectroscopy (FCS) is a popular technique, complementary to cell imaging for the investigation of dynamic processes in living cells. Based on fluorescence, this single molecule method suffers from artifacts originating from the poor fluorophore photophysics: photobleaching, blinking, and saturation. To circumvent these limitations we present here a new correlation method called photothermal absorption correlation spectroscopy (PhACS) which relies on the absorption properties of tiny nano-objects. PhACS is based on the photothermal heterodyne detection technique and measures akin FCS, the time correlation function of the detected signals. Application of this technique to the precise determination of the hydrodynamic sizes of different functionalized gold nanoparticles are presented, highlighting the potential of this method. PMID:19236070

  20. Acetaminophen (paracetamol) oral absorption and clinical influences.

    PubMed

    Raffa, Robert B; Pergolizzi, Joseph V; Taylor, Robert; Decker, John F; Patrick, Jeffrey T

    2014-09-01

    Acetaminophen (paracetamol) is a widely used nonopioid, non-NSAID analgesic that is effective against a variety of pain types, but the consequences of overdose can be severe. Because acetaminophen is so widely available as a single agent and is increasingly being formulated in fixed-ratio combination analgesic products for the potential additive or synergistic analgesic effect and/or reduced adverse effects, accidental cumulative overdose is an emergent concern. This has rekindled interest in the sites, processes, and pharmacokinetics of acetaminophen oral absorption and the clinical factors that can influence these. The absorption of oral acetaminophen occurs primarily along the small intestine by passive diffusion. Therefore, the rate-limiting step is the rate of gastric emptying into the intestines. Several clinical factors can affect absorption per se or the rate of gastric emptying, such as diet, concomitant medication, surgery, pregnancy, and others. Although acetaminophen does not have the abuse potential of opioids or the gastrointestinal bleeding or organ adverse effects of NSAIDs, excess amounts can produce serious hepatic injury. Thus, an understanding of the sites and features of acetaminophen absorption--and how they might be influenced by factors encountered in clinical practice--is important for pain management using this agent. It can also provide insight for design of formulations that would be less susceptible to clinical variables.

  1. Acetaminophen (paracetamol) oral absorption and clinical influences.

    PubMed

    Raffa, Robert B; Pergolizzi, Joseph V; Taylor, Robert; Decker, John F; Patrick, Jeffrey T

    2014-09-01

    Acetaminophen (paracetamol) is a widely used nonopioid, non-NSAID analgesic that is effective against a variety of pain types, but the consequences of overdose can be severe. Because acetaminophen is so widely available as a single agent and is increasingly being formulated in fixed-ratio combination analgesic products for the potential additive or synergistic analgesic effect and/or reduced adverse effects, accidental cumulative overdose is an emergent concern. This has rekindled interest in the sites, processes, and pharmacokinetics of acetaminophen oral absorption and the clinical factors that can influence these. The absorption of oral acetaminophen occurs primarily along the small intestine by passive diffusion. Therefore, the rate-limiting step is the rate of gastric emptying into the intestines. Several clinical factors can affect absorption per se or the rate of gastric emptying, such as diet, concomitant medication, surgery, pregnancy, and others. Although acetaminophen does not have the abuse potential of opioids or the gastrointestinal bleeding or organ adverse effects of NSAIDs, excess amounts can produce serious hepatic injury. Thus, an understanding of the sites and features of acetaminophen absorption--and how they might be influenced by factors encountered in clinical practice--is important for pain management using this agent. It can also provide insight for design of formulations that would be less susceptible to clinical variables. PMID:26013309

  2. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  3. [Intestinal absorption kinetics of Polygonum capitatum extract in rats].

    PubMed

    Yang, Wu; Hou, Jia; Lu, Yuan; Chen, Peng-cheng; Liao, Shang-gao; Huang, Yong

    2015-11-01

    A UPLC-ESI-MS/MS method was used to determinate the main active fractions gallic acid, protocatechuic acid, myricetrin, hyperoside and quercitrin in Polygonum capitatum extracts by in situ intestinal perfusion models; the absorption rate constants and cumulative penetration rate of absorption were calculated. The effect of different drug concentrations, different intestine segments, bile and P-gp inhibitors on the absorption mechanism of Gallic acid and other compositions in P. capitatum extracts. The experimental results showed that gallic acid, protocatechuic acid, myricetrin and quercitrin were observed saturated at high concentration (P < 0.05). Bile had significant inhibition effect on protocatechuic acid absorption and had promotion effect on myricetrin and hyperoside absorption (P < 0.05). P-gp inhibitor verapamil could significantly enhance the absorption of Protocatechuic acid (P < 0.05). The overall trend for absorption of various compositions was that small intestine > colon. This indicated that the absorption mechanism of P. capitatum extracts in rat intestine was in line with fist-order kinetics characteristics. The composition could be absorbed in all of the different intestinal segments, and the absorption was mainly concentrated in small intestine. The protocatechuic acid may be the substrate of P-gp.

  4. [Intestinal absorption kinetics of Polygonum capitatum extract in rats].

    PubMed

    Yang, Wu; Hou, Jia; Lu, Yuan; Chen, Peng-cheng; Liao, Shang-gao; Huang, Yong

    2015-11-01

    A UPLC-ESI-MS/MS method was used to determinate the main active fractions gallic acid, protocatechuic acid, myricetrin, hyperoside and quercitrin in Polygonum capitatum extracts by in situ intestinal perfusion models; the absorption rate constants and cumulative penetration rate of absorption were calculated. The effect of different drug concentrations, different intestine segments, bile and P-gp inhibitors on the absorption mechanism of Gallic acid and other compositions in P. capitatum extracts. The experimental results showed that gallic acid, protocatechuic acid, myricetrin and quercitrin were observed saturated at high concentration (P < 0.05). Bile had significant inhibition effect on protocatechuic acid absorption and had promotion effect on myricetrin and hyperoside absorption (P < 0.05). P-gp inhibitor verapamil could significantly enhance the absorption of Protocatechuic acid (P < 0.05). The overall trend for absorption of various compositions was that small intestine > colon. This indicated that the absorption mechanism of P. capitatum extracts in rat intestine was in line with fist-order kinetics characteristics. The composition could be absorbed in all of the different intestinal segments, and the absorption was mainly concentrated in small intestine. The protocatechuic acid may be the substrate of P-gp. PMID:27071271

  5. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  6. Effect of absorption promoters on subcutaneous absorption of human epidermal growth factor in rats.

    PubMed

    Murakami, T; Misaki, M; Kojima, Y; Yamada, M; Yuki, M; Higashi, Y; Amagase, H; Fuwa, T; Yata, N

    1993-03-01

    Subcutaneous administration of human epidermal growth factor (hEGF) to rats gave a significantly smaller value of area under the curve (AUC) of concentration in plasma of immunoreactive hEGF versus time than intravenous administration, probably because the slow entry rate into the blood circulation and consequently the enzymic degradation of hEGF at the injection site. In the present study, absorption promoters such as sodium caprate, N-acylamino acids, disodium ethylenediamine-tetraacetate (EDTA), and sodium glycocholate were used because they were expected to inhibit the enzymic degradation of hEGF at the injection site and to facilitate the entry of hEGF into the blood circulation. Coadministration of an absorption promoter with hEGF significantly increased the entry rate and AUC value of immunoreactive hEGF compared with the case without the absorption promoter. The enzymic degradation of hEGF in the supernatant of the rat subcutaneous tissue homogenates and in the buffer solution containing leucine aminopeptidase or protease was markedly inhibited by the presence of the absorption promoters except EDTA. On the other hand, only EDTA increased the initial entry rate of FITC-dextran (M(r), 4000), which is not metabolized at the injection site, although all absorption promoters including EDTA markedly increased the extravasation of Evans blue. Thus, the increased subcutaneous bioavailability of hEGF in the presence of absorption promoters (except EDTA) was mainly attributed to the inhibitory effect of absorption promoters against the enzymic degradation of hEGF at the subcutaneous tissues. PMID:7680713

  7. Effect of partial absorption on diffusion with resetting.

    PubMed

    Whitehouse, Justin; Evans, Martin R; Majumdar, Satya N

    2013-02-01

    The effect of partial absorption on a diffusive particle which stochastically resets its position with a finite rate r is considered. The particle is absorbed by a target at the origin with absorption "velocity" a; as the velocity a approaches ∞ the absorption property of the target approaches that of a perfectly absorbing target. The effect of partial absorption on first-passage time problems is studied, in particular, it is shown that the mean time to absorption (MTA) is increased by an additive term proportional to 1/a. The results are extended to multiparticle systems where independent searchers, initially uniformly distributed with a given density, look for a single immobile target. It is found that the average survival probability P(av) is modified by a multiplicative factor which is a function of 1/a, whereas the decay rate of the typical survival probability P(typ) is decreased by an additive term proportional to 1/a.

  8. Effect of partial absorption on diffusion with resetting

    NASA Astrophysics Data System (ADS)

    Whitehouse, Justin; Evans, Martin R.; Majumdar, Satya N.

    2013-02-01

    The effect of partial absorption on a diffusive particle which stochastically resets its position with a finite rate r is considered. The particle is absorbed by a target at the origin with absorption “velocity” a; as the velocity a approaches ∞ the absorption property of the target approaches that of a perfectly absorbing target. The effect of partial absorption on first-passage time problems is studied, in particular, it is shown that the mean time to absorption (MTA) is increased by an additive term proportional to 1/a. The results are extended to multiparticle systems where independent searchers, initially uniformly distributed with a given density, look for a single immobile target. It is found that the average survival probability Pav is modified by a multiplicative factor which is a function of 1/a, whereas the decay rate of the typical survival probability Ptyp is decreased by an additive term proportional to 1/a.

  9. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  10. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  11. Modular total absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Karny, M.; Rykaczewski, K. P.; Fijałkowska, A.; Rasco, B. C.; Wolińska-Cichocka, M.; Grzywacz, R. K.; Goetz, K. C.; Miller, D.; Zganjar, E. F.

    2016-11-01

    The design and performance of the Modular Total Absorption Spectrometer built and commissioned at the Oak Ridge National Laboratory is presented. The active volume of the detector is approximately one ton of NaI(Tl), which results in very high full γ energy peak efficiency of 71% at 6 MeV and nearly flat efficiency of around 81.5% for low energy γ-rays between 300 keV and 1 MeV. In addition to the high peak efficiency, the modular construction of the detector permits the use of a γ-coincidence technique in data analysis as well as β-delayed neutron observation.

  12. Real-time absorption reduced surface fluorescence imaging

    PubMed Central

    Yang, Bin; Tunnell, James W.

    2014-01-01

    Abstract. We introduce a technique that limits absorption effects in fluorescence imaging and does not require extensive imaging processing, thus allowing for video rate imaging. The absorption minimization is achieved using spatial frequency domain imaging at a single high spatial frequency with standard three-phase demodulation. At a spatial frequency f=0.5  mm−1, we demonstrated in both in-vitro phantoms and ex-vivo tissue that the absorption can be significantly reduced. In the real-time implementation, we achieved a video rate of 19  frames/s. This technique has potential in cancer visualization and tumor margin detection. PMID:25250826

  13. Real-time absorption reduced surface fluorescence imaging.

    PubMed

    Yang, Bin; Tunnell, James W

    2014-09-01

    We introduce a technique that limits absorption effects in fluorescence imaging and does not require extensive imaging processing, thus allowing for video rate imaging. The absorption minimization is achieved using spatial frequency domain imaging at a single high spatial frequency with standard three-phase demodulation. At a spatial frequency f ¼ 0.5 mm−1, we demonstrated in both in-vitro phantoms and ex-vivo tissue that the absorption can be significantly reduced. In the real-time implementation, we achieved a video rate of 19 frames∕s. This technique has potential in cancer visualization and tumor margin detection. PMID:25250826

  14. Light absorption properties and absorption budget of Southeast Pacific waters

    NASA Astrophysics Data System (ADS)

    Bricaud, Annick; Babin, Marcel; Claustre, Hervé; Ras, JoséPhine; TièChe, Fanny

    2010-08-01

    Absorption coefficients of phytoplankton, nonalgal particles (NAPs), and colored dissolved organic matter (CDOM), and their relative contributions to total light absorption, are essential variables for bio-optical and biogeochemical models. However, their actual variations in the open ocean remain poorly documented, particularly for clear waters because of the difficulty in measuring very low absorption coefficients. The Biogeochemistry and Optics South Pacific Experiment (BIOSOPE) cruise investigated a large range of oceanic regimes, from mesotrophic waters around the Marquesas Islands to hyperoligotrophic waters in the subtropical gyre and eutrophic waters in the upwelling area off Chile. The spectral absorption coefficients of phytoplankton and NAPs were determined using the filter technique, while the CDOM absorption coefficients were measured using a 2 m capillary waveguide. Over the whole transect, the absorption coefficients of both dissolved and particulate components covered approximately two orders of magnitude; in the gyre, they were among the lowest ever reported for open ocean waters. In the oligotrophic and mesotrophic waters, absorption coefficients of phytoplankton and NAPs were notably lower than those measured in other oceanic areas with similar chlorophyll contents, indicating some deviation from the standard chlorophyll-absorption relationships. The contribution of absorption by NAPs to total particulate absorption showed large vertical and horizontal variations. CDOM absorption coefficients covaried with algal biomass, albeit with a high scatter. The spectral slopes of both NAP and CDOM absorption revealed structured spatial variability in relation with the trophic conditions. The relative contributions of each component to total nonwater absorption were (at a given wavelength) weakly variable over the transect, at least within the euphotic layer.

  15. Absorption Changes in Bacterial Chromatophores

    PubMed Central

    Kuntz, Irwin D.; Loach, Paul A.; Calvin, Melvin

    1964-01-01

    The magnitude and kinetics of photo-induced absorption changes in bacterial chromatophores (R. rubrum, R. spheroides and Chromatium) have been studied as a function of potential, established by added redox couples. No photochanges can be observed above +0.55 v or below -0.15 v. The loss of signal at the higher potential is centered at +0.439 v and follows a one-electron change. The loss of signal at the lower potential is centered at -0.044 v and is also consistent with a one-electron change. Both losses are reversible. A quantitative relationship exists between light-minus-dark and oxidized-minus-reduced spectra in the near infrared from +0.30 to +0.55 v. Selective treatment of the chromatophores with strong oxidants irreversibly bleaches the bulk pigments but appears to leave intact those pigments responsible for the photo- and chemically-induced absorption changes. Kinetic studies of the photochanges in deaerated samples of R. rubrum chromatophores revealed the same rise time for bands at 433, 792, and 865 mμ (t½ = 50 msec.). However, these bands had different decay rates (t½ = 1.5, 0.5, 0.15 sec., respectively), indicating that they belong to different pigments. Analysis of the data indicates, as the simplest interpretation, a first-order (or pseudo first-order) forward reaction and two parallel first-order (or pseudo first-order) decay reactions at each wavelength. These results imply that all pigments whose kinetics are given are photooxidized and the decay processes are dark reductions. These experiments are viewed as supporting and extending the concept of a bacterial photosynthetic unit, with energy migration within it to specific sites of electron transfer. PMID:14185583

  16. Enhanced absorption cycle computer model. Final report

    SciTech Connect

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperatures boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorptions systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system`s components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H{sub 2}O triple-effect cycles, LiCl-H{sub 2}O solar-powered open absorption cycles, and NH{sub 3}-H{sub 2}O single-effect and generator-absorber heat exchange cycles. An appendix contains the User`s Manual.

  17. CO2 Capture from Flue Gas by Phase Transitional Absorption

    SciTech Connect

    Liang Hu

    2009-06-30

    A novel absorption process called Phase Transitional Absorption was invented. What is the Phase Transitional Absorption? Phase Transitional Absorption is a two or multi phase absorption system, CO{sub 2} rich phase and CO{sub 2} lean phase. During Absorption, CO{sub 2} is accumulated in CO{sub 2} rich phase. After separating the two phases, CO{sub 2} rich phase is forward to regeneration. After regeneration, the regenerated CO{sub 2} rich phase combines CO{sub 2} lean phase to form absorbent again to complete the cycle. The advantage for Phase Transitional Absorption is obvious, significantly saving on regeneration energy. Because CO{sub 2} lean phase was separated before regeneration, only CO{sub 2} rich phase was forward to regeneration. The absorption system we developed has the features of high absorption rate, high loading and working capacity, low corrosion, low regeneration heat, no toxic to environment, etc. The process evaluation shows that our process is able to save 80% energy cost by comparing with MEA process.

  18. [Absorption of extractive Polygonum orientale in rat everted gut sacs].

    PubMed

    Liu, Yue; Tang, Li; Cao, Xu; Zheng, Lin; Wang, Ai-Min; Huang, Yong

    2014-06-01

    Using in vitro everted gut to investigate the intestinal absorption of the extracts from Polygonum orientale at different concentration. UPLC-MS/MS was used to detect the content of protocatechuic acid, isoorientin, orientin, vitexin, cynaroside, quercitrin, kaempferol-rhamnoside in different intestinal segments, then compared the results with the absorption of chemical components of extractive P. orientale in each intestinal segments, and calculated the absorption parameter. We took the statistic analysis with SPSS statistic software. The influence significance of each factors were analyzed to describe the character of absorption. The absorption of each component is linearity in different intestinal segments and different dose, and the square of coeficient correlation exceed 0.95, which consistent with zero order rate process. The K(a) increase along with the raised dosage of the extractive P. orientale (R2 > 0.95), indicated it is the passive absorption; different intestinal segments have different absorption. And the absorption trend in intestinal is duodenum, jejunum, ileum are greater than the colon. As ingredients are selectively absorbed in intestinal sac, the everted intestinal sac method is selected to assess the intestinal absorption charcteristics of ingredients of extractive P. orientale. PMID:25272855

  19. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

  20. Percutaneous absorption in preterm infants.

    PubMed

    West, D P; Halket, J M; Harvey, D R; Hadgraft, J; Solomon, L M; Harper, J I

    1987-11-01

    The skin of preterm infants varies considerably in its level of maturity. To understand skin absorption in premature infants better, we report a technique for the assessment of percutaneous absorption at various gestational and postnatal ages using stable, isotope-labeled (13C6) benzoic acid. Our results indicate that in the preterm infant, this method detects enhanced skin absorption in the first postnatal days, which declines over three weeks to that expected of a full-term infant. This approach also indicates an inverse relationship between gestational age and skin absorption, as well as postnatal age and skin absorption. The reported technique is a safe and noninvasive method using a model skin penetrant for the study of percutaneous absorption in preterm infants from which basic data may be derived to add to our understanding of skin barrier function. PMID:3422856

  1. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  2. Energy Absorption in a Shear-Thickening Fluid

    NASA Astrophysics Data System (ADS)

    Afeshejani, Seyed Hossein Amiri; Sabet, Seyed Ali Reza; Zeynali, Mohammad Ebrahim; Atai, Mohammad

    2014-12-01

    This study investigates energy absorption in a shear-thickening fluid (STF) containing nano-size fumed silica as a suspending material. Fumed silica particles in 20, 30, and 40 wt.% were used in polyethylene glycol and ethylene glycol. Three areas were studied, namely: energy absorption of STF pre-impregnated aramid fabric, neat STF under high-velocity impact, and flexible foam soaked in STF under low-velocity drop weight impact. Results showed moderate energy absorption in STF pre-impregnated aramid fabric compared to dry fabric. High-velocity impact tests also revealed higher fabric weave density, and multi-layered target plays vital role in optimum performance of SFT impregnated targets. High-velocity impact tests on the neat STF showed good energy absorption at velocities near STF critical shear rate. Low-velocity drop weight impact test on flexible foam soaked in STF also indicated significant energy absorption.

  3. Temperature effects on dynamic water absorption into paper.

    PubMed

    Songok, Joel; Salminen, Pekka; Toivakka, Martti

    2014-03-15

    Mechanisms controlling short time water absorption and the effect of temperature on water absorption into paper were investigated by analyzing previously published data. A dynamic contact angle effect caused by contact line friction explained the liquid uptake dynamics at short times. The water absorption rate increase with temperature is suggested to be controlled by the molecular processes occurring in front of the advancing liquid front. The increase in the non-equilibrium vapor pressure at air-liquid interface leads to higher water molecule adsorption onto fibers and associated lowering of the solid-gas interfacial tension, thereby increasing the wetting velocity and water absorption. The classical Lucas-Washburn equation was found to be inadequate for predicting water absorption into paper both at short times and as a function of temperature. PMID:24461858

  4. Mathematical analysis of dermal absorption rate of heavy metals.

    PubMed

    Batkin, Izmail; Bolic, Miodrag

    2015-08-01

    Presently 90 - 95% of children in the US wear disposable diapers before completing their toilet training at average age of 30 months. The diaper absorbs urine and liquid component from feces contaminated with excreted toxicants. In this initial study, we posit that the long contact between the diaper and the skin leads to increased dermal reabsorption of excreted body toxicants, mainly heavy metals, which are statistically associated with autism and neurodevelopmental disorder. We developed a mathematical model to analyse the increase of the level of toxicants due to dermal reabsorption after excretion. This simple kinetic model gives us the average reabsorbtion factor in the range of 1.6 to 5. The limitation of this work is that only mathematical model has been considered and it has not been verified experimentally.

  5. Study on moisture absorption and sweat discharge of honeycomb polyester fiber

    NASA Astrophysics Data System (ADS)

    Feng, Aifen; Zhang, Yongjiu

    2015-07-01

    The moisture absorption and liberation properties of honeycomb polyester fiber were studied in order to understand its moisture absorption and sweat discharge. Through testing moisture absorption and liberation regains of honeycomb polyester fiber and normal polyester fiber in standard atmospheric conditions, their moisture absorption and liberation curves were depicted, and the regression equations of moisture regains to time during their reaching the balance of moisture absorption and moisture liberation were obtained according to the curves. Their moisture absorption and liberation rate curves were analyzed and the regression equations of the rates to time were obtained. The results shows that the moisture regain of honeycomb polyester fiber is much bigger than the normal polyester fiber's, and the initial moisture absorption and moisture liberation rates of the former are much higher than the latter's, so that the moisture absorbance and sweat discharge of honeycomb polyester fiber are excellent.

  6. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  7. Absorption, metabolism and effect of compatibility on absorption of qishenyiqi dropping pill.

    PubMed

    Han, Yan-Qi; Wang, Jing; Cui, Qing-Xin; Wang, Li-Qiang; Cheng, Bin-Feng; Zhao, Hong-Zhi; Jiang, Min; Bai, Gang; Luo, Guo-An

    2014-04-01

    Qishenyiqi dropping pill (QSYQ), is a traditional Chinese medicine (TCM) prescription for treating heart diseases in China. Knowledge concerning the systemic identification of active compounds and metabolic components of QSYQ is generally lacking. Therefore, it is essential to develop a valid method for the analysis of active compounds of the combined prescription and determination of interactions among the herbs. The absorbable compounds and metabolites of QSYQ were profiled using computational chemistry prediction, an improved everted gut sac in vitro experiment, the Caco-2 cell monolayer in vitro test, a rat in vivo experiment and ultra-performance liquid chromatography/diode array detection/quadrupole-time of flight mass spectrum (UPLC/DAD/Q-TOF MS). In total, 42 prototype compounds were recognized as absorbable compounds, and eight metabolites were identified by UPLC/DAD/Q-TOF MS. The absorption rates of phenolic acids and saponins were significantly improved and the absorption of isoflavone was inhibited after compatibility. The volatile oil component had an improved effect on the absorption of other compounds, while its own absorption was inhibited. In conclusion, the present study established a rapid and effective strategy for demonstrating the absorption and metabolism of QSYQ and revealing the compatible relationship among herbs. This investigation can provide a reference for the compatibility of prescriptions and the modernization of TCM.

  8. Optimal design of porous structures for the fastest liquid absorption.

    PubMed

    Shou, Dahua; Ye, Lin; Fan, Jintu; Fu, Kunkun

    2014-01-14

    Porous materials engineered for rapid liquid absorption are useful in many applications, including oil recovery, spacecraft life-support systems, moisture management fabrics, medical wound dressings, and microfluidic devices. Dynamic absorption in capillary tubes and porous media is driven by the capillary pressure, which is inversely proportional to the pore size. On the other hand, the permeability of porous materials scales with the square of the pore size. The dynamic competition between these two superimposed mechanisms for liquid absorption through a heterogeneous porous structure may lead to an overall minimum absorption time. In this work, we explore liquid absorption in two different heterogeneous porous structures [three-dimensional (3D) circular tubes and porous layers], which are composed of two sections with variations in radius/porosity and height. The absorption time to fill the voids of porous constructs is expressed as a function of radius/porosity and height of local sections, and the absorption process does not follow the classic Washburn's law. Under given height and void volume, these two-section structures with a negative gradient of radius/porosity against the absorption direction are shown to have faster absorption rates than control samples with uniform radius/porosity. In particular, optimal structural parameters, including radius/porosity and height, are found that account for the minimum absorption time. The liquid absorption in the optimized porous structure is up to 38% faster than in a control sample. The results obtained can be used a priori for the design of porous structures with excellent liquid management property in various fields.

  9. Optical absorption of silicon nanowires

    SciTech Connect

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stievenard, D.; Leveque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-08-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  10. Nonlinear intestinal absorption kinetics of cefuroxime axetil in rats.

    PubMed Central

    Ruiz-Balaguer, N; Nacher, A; Casabo, V G; Merino, M

    1997-01-01

    Cefuroxime is commercially available for parenteral administration as a sodium salt and for oral administration as cefuroxime axetil, the 1-(acetoxy)ethyl ester of the drug. Cefuroxime axetil is a prodrug of cefuroxime and has little, if any, antibacterial activity until hydrolyzed in vivo to cefuroxime. In this study, the absorption of cefuroxime axetil in the small intestines of anesthetized rats was investigated in situ, by perfusion at four concentrations (11.8, 5, 118 and 200 microM). Oral absorption of cefuroxime axetil can apparently be described as a specialized transport mechanism which obeys Michaelis-Menten kinetics. Parameters characterizing absorption of prodrug in free solution were obtained: maximum rate of absorption (Vmax) = 289.08 +/- 46.26 microM h-1, and Km = 162.77 +/- 31.17 microM. Cefuroxime axetil transport was significantly reduced in the presence of the enzymatic inhibitor sodium azide. On the other hand, the prodrug was metabolized in the gut wall through contact with membrane-bound enzymes in the brush border membrane before absorption occurred. This process reduces the prodrug fraction directly available for absorption. From a bioavailability point of view, therefore, the effects mentioned above can explain the variable and poor bioavailability following oral administration of cefuroxime axetil. Thus, future strategies in oral cefuroxime axetil absorption should focus on increasing the stability of the prodrug in the intestine by modifying the prodrug structure and/or targeting the compound to the absorption site. PMID:9021205

  11. Microscopic Theory and Simulation of Quantum-Well Intersubband Absorption

    NASA Technical Reports Server (NTRS)

    Li, Jianzhong; Ning, C. Z.

    2004-01-01

    We study the linear intersubband absorption spectra of a 15 nm InAs quantum well using the intersubband semiconductor Bloch equations with a three-subband model and a constant dephasing rate. We demonstrate the evolution of intersubband absorption spectral line shape as a function of temperature and electron density. Through a detailed examination of various contributions, such as the phase space filling effects, the Coulomb many-body effects and the non-parabolicity effect, we illuminate the underlying physics that shapes the spectra. Keywords: Intersubband transition, linear absorption, semiconductor heterostructure, InAs quantum well

  12. Spectrophotometry of six broad absorption line QSOs

    NASA Technical Reports Server (NTRS)

    Junkkarinen, Vesa T.; Burbidge, E. Margaret; Smith, Harding E.

    1987-01-01

    Spectrophotometric observations of six broad absorption-line QSOs (BALQSOs) are presented. The continua and emission lines are compared with those in the spectra of QSOs without BALs. A statistically significant difference is found in the emission-line intensity ratio for (N V 1240-A)/(C IV 1549-A). The median value of (N V)/(C IV) for the BALQSOs is two to three times the median for QSOs without BALs. The absorption features of the BALQSOs are described, and the column densities and limits on the ionization structure of the BAL region are discussed. If the dominant ionization mechanism is photoionization, then it is likely that either the ionizing spectrum is steep or the abundances are considerably different from solar. Collisional ionization may be a significant factor, but it cannot totally dominate the ionization rate.

  13. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  14. Ultraviolet absorption spectrum of hydrogen peroxide vapor. [for atmospheric abundances

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Schinke, S. D.; Molina, M. J.

    1977-01-01

    The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.

  15. Estimation of microwave absorption in the Jupiter atmosphere

    NASA Technical Reports Server (NTRS)

    Coombs, W. C.

    1971-01-01

    A procedure for estimating the microwave absorption loss of the Jupiter atmosphere is presented. Estimation of microwave absorption by planetary atmospheres involves two different investigative disciplines (1) the determination of an acceptable model of the atmosphere itself and (2) the determination of the microwave attenuation rate applicable to each different volume sample of the atmosphere, and the integration of this loss over the varying radio propagation path for any given entry trajectory to obtain the total loss.

  16. Analysis of sequential events in intestinal absorption of folylpolyglutamate

    SciTech Connect

    Darcy-Vrillon, B.; Selhub, J.; Rosenberg, I.H.

    1988-09-01

    Although it is clear that the intestinal absorption of folylpolyglutamates is associated with hydrolysis to monoglutamyl folate, the precise sequence and relative velocity of the events involved in this absorption are not fully elucidated. In the present study, we used biosynthetic, radiolabeled folylpolyglutamates purified by affinity chromatography to analyze the relationship of hydrolysis and transport in rat jejunal loops in vivo. Absorption was best described by a series of first-order processes: luminal hydrolysis to monoglutamyl folate followed by tissue uptake of the product. The rate of hydrolysis in vivo was twice as high as the rate of transport. The latter value was identical to that measured for folic acid administered separately. The relevance of this sequential model was confirmed by data obtained using inhibitors of the individual steps in absorption of ''natural'' folate. Heparin and sulfasalazine were both effective in decreasing absorption. The former affected hydrolysis solely, whereas the latter acted as a competitive inhibitor of transport of monoglutamyl folate. These studies confirm that hydrolysis is obligatory and that the product is subsequently taken up by a transport process, common to monoglutamyl folates, that is the rate-determining step in transepithelial absorption.

  17. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  18. Percutaneous absorption of Octopirox.

    PubMed

    Black, J G; Kamat, V B

    1988-01-01

    containing 1% Octopirox is 29,400, so that the possibility of systemic effects due to absorption through the skin is remote. PMID:3345970

  19. Resonant Absorption of Bessel Beams

    NASA Astrophysics Data System (ADS)

    Fan, J.; Parra, E.; Milchberg, H. M.

    1999-11-01

    We report the first observation of enhanced laser-plasma optical absorption in a subcritical density plasma resulting from spatial resonances, here in the laser breakdown of a gas with a Bessel beam. The enhancement in absorption is directly correlated to enhancements both in confinement of laser radiation to the plasma and in its heating. Under certain conditions, azimuthal asymmetry in the laser beam is essential for efficient gas breakdown. Simulations of this absorption consistently explain the experimental observations. This work is supported by the National Science Foundation (PHY-9515509) and the US Department of Energy (DEF G0297 ER 41039).

  20. Application of the mathematical Graf's addition theorem to the problem of electron energy absorption in laser-irradiated plasma

    NASA Astrophysics Data System (ADS)

    Krainov, V. P.

    2013-03-01

    The electron energy absorption in laser-irradiated plasma is determined by the sum of the rates of photon absorption and emission. These rates contain the square of the Bessel functions. It was shown that in a moderate laser field, terms with absorption and emission of several photons are large, but cancel exactly each other. Therefore, we should take into account terms with the absorption and emission of only one laser photon. This statement is proved analytically using Graf's theorem for Bessel functions.

  1. Analysis of the Solar Radiation Impact on Cooling Performance of the Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Fedorčák, Pavol; Košičanová, Danica; Nagy, Richard; Mlynár, Peter

    2014-11-01

    Absorption cooling at low power is a new technology which has not yet been applied to current conditioning elements. This paper analyzes the various elements of solar absorption cooling. Individual states were simulated in which working conditions were set for the capability of solar absorption cooling to balance heat loads in the room. The research is based on an experimental device (absorption units with a performance of 10kW) developed at the STU in Bratislava (currently inputs and outputs of cold sources are being measured). Outputs in this paper are processed so that they connect the entire scheme of the solar absorption cooling system (i.e. the relationship between the solar systems hot and cold storage and the absorption unit). To determine the size of the storage required, calculated cooling for summer months is considered by the ramp rate of the absorption unit and required flow rate of the collectors.

  2. [Absorption of aqueous extracts from Salviae Miltiorrhizae Radix et Rhizoma by everted intestinal sac method].

    PubMed

    Zhao, Jie; Xu, Xue-lin; Yi, Hong; Zhang, Hong-min; Liu, Xiao-qian; Zhu, Jing-jing; Wang, Zhi-min

    2015-08-01

    To study the absorptive characteristics of aqueous extracts from Salviae Miltiorrhizae Radix et Rhizoma by in vitro rat everted intestinal sac model. Three representative ingredients in aqueous extracts from Salviae Miltiorrhizae Radix et Rhizome--protocatechuic aldehyde (PAL), posmarinic acid (RA) and salvianolic acid B (SAB), were selected as the study objects. An UPLC method was established to determine and measure their cumulative absorption amount, in order to explain the absorption characteristics of ingredients in different intestinal sections. According to the experimental result, RA and SAB showed the passive absorption in ileum, which conformed to the first-order absorption rate; with low and medium doses, they showed a zero-order absorption rate in jejunum, which was reflected in the coexistence of both positive and passive absorptions; PAL showed a passive absorption manner both in ileum and jejunum. According to the experiment for absorption in different intestinal sections, RA and SAB were mainly absorbed in jejunum, while PAL was absorbed mainly in ileum. All of the three ingredients in aqueous extracts from Salviae Miltiorrhizae Radix et rhizome--PAL, RA and SAB could be absorbed in intestines, but with differences in the absorption rate and mechanism, which indicated that the intestinal absorption of aqueous extracts from Salviae Miltiorrhizae Radix et rhizome was selectivity, instead of a simple semi-permeable membrane penetration process.

  3. Inhibitor of intramembranous absorption in ovine amniotic fluid.

    PubMed

    Brace, Robert A; Cheung, Cecilia Y; Anderson, Debra F

    2014-02-01

    Intramembranous absorption increases during intra-amniotic infusion of physiological saline solutions. The increase may be due partly to the concomitant elevation in fetal urine production as fetal urine contains a stimulator of intramembranous absorption. In this study, we hypothesized that the increase in intramembranous absorption during intra-amniotic infusion is due, in part, to dilution of a nonrenal inhibitor of intramembranous absorption that is present in amniotic fluid. In late-gestation fetal sheep, amniotic fluid volume and the four primary amniotic inflows and outflows were determined over 2-day intervals under three conditions: 1) control conditions when fetal urine entered the amniotic sac, 2) during intra-amniotic infusion of 2 l/day of lactated Ringer solution when urine entered the amniotic sac, and 3) during the same intra-amniotic infusion when fetal urine was continuously replaced with lactated Ringer solution. Amniotic fluid volume, fetal urine production, swallowed volume, and intramembranous absorption rate increased during the infusions independent of fetal urine entry into the amniotic sac or its replacement. Lung liquid secretion rate was unchanged during infusion. Because fetal membrane stretch has been shown not to be involved and because urine replacement did not alter the response, we conclude that the increase in intramembranous absorption that occurs during intra-amniotic infusions is due primarily to dilution of a nonrenal inhibitor of intramembranous absorption that is normally present in amniotic fluid. This result combined with our previous study suggests that a nonrenal inhibitor(s) together with a renal stimulator(s) interact to regulate intramembranous absorption rate and, hence, amniotic fluid volume.

  4. Inhibitor of intramembranous absorption in ovine amniotic fluid

    PubMed Central

    Cheung, Cecilia Y.; Anderson, Debra F.

    2013-01-01

    Intramembranous absorption increases during intra-amniotic infusion of physiological saline solutions. The increase may be due partly to the concomitant elevation in fetal urine production as fetal urine contains a stimulator of intramembranous absorption. In this study, we hypothesized that the increase in intramembranous absorption during intra-amniotic infusion is due, in part, to dilution of a nonrenal inhibitor of intramembranous absorption that is present in amniotic fluid. In late-gestation fetal sheep, amniotic fluid volume and the four primary amniotic inflows and outflows were determined over 2-day intervals under three conditions: 1) control conditions when fetal urine entered the amniotic sac, 2) during intra-amniotic infusion of 2 l/day of lactated Ringer solution when urine entered the amniotic sac, and 3) during the same intra-amniotic infusion when fetal urine was continuously replaced with lactated Ringer solution. Amniotic fluid volume, fetal urine production, swallowed volume, and intramembranous absorption rate increased during the infusions independent of fetal urine entry into the amniotic sac or its replacement. Lung liquid secretion rate was unchanged during infusion. Because fetal membrane stretch has been shown not to be involved and because urine replacement did not alter the response, we conclude that the increase in intramembranous absorption that occurs during intra-amniotic infusions is due primarily to dilution of a nonrenal inhibitor of intramembranous absorption that is normally present in amniotic fluid. This result combined with our previous study suggests that a nonrenal inhibitor(s) together with a renal stimulator(s) interact to regulate intramembranous absorption rate and, hence, amniotic fluid volume. PMID:24381178

  5. Percutaneous nitroglycerin absorption in rats.

    PubMed

    Horhota, S T; Fung, H L

    1979-05-01

    Percutaneous nitroglycerin absorption was studied in shaved rats by monitoring unchanged plasma drug concentrations for up to 4 hr. Drug absorption from the neat liquid state or from an alcoholic solution was considerably poorer than that from a commercial ointment. This observation was unanticipated since the driving force for percutaneous drug absorption was assumed to be drug thermodynamics. Potential artifacts such as drug volatilization from the skin, reduction of surface area through droplet formation, and vehicle occlusion were investigated, but they did not appear to be responsible for the observed results. Two experimental aqueous nitroglycerin gels were prepared with polyethylene glycol 400. One gel contained just sufficient polyethylene glycol to solubilize the nitroglycerin; the other had excess polyethylene glycol to solubilize nitroglycerin far below saturation. Both gels gave extremely low plasma nitroglycerin levels. The composite data suggested that percutaneous nitroglycerin absorption is highly vehicle dependent and that this dependency cannot be explained by simple consideration of drug thermodynamic activity.

  6. Circadian Regulation of Macronutrient Absorption.

    PubMed

    Hussain, M Mahmood; Pan, Xiaoyue

    2015-12-01

    Various intestinal functions exhibit circadian rhythmicity. Disruptions in these rhythms as in shift workers and transcontinental travelers are associated with intestinal discomfort. Circadian rhythms are controlled at the molecular level by core clock and clock-controlled genes. These clock genes are expressed in intestinal cells, suggesting that they might participate in the circadian regulation of intestinal functions. A major function of the intestine is nutrient absorption. Here, we will review absorption of proteins, carbohydrates, and lipids and circadian regulation of various transporters involved in their absorption. A better understanding of circadian regulation of intestinal absorption might help control several metabolic disorders and attenuate intestinal discomfort associated with disruptions in sleep-wake cycles.

  7. Effects of solvent on percutaneous absorption of nonvolatile lipophilic solute.

    PubMed

    Intarakumhaeng, Rattikorn; Li, S Kevin

    2014-12-10

    Understanding the effects of solvents upon percutaneous absorption can improve drug delivery across skin and allow better risk assessment of toxic compound exposure. The objective of the present study was to examine the effects of solvents upon the deposition of a moderately lipophilic solute at a low dose in the stratum corneum (SC) that could influence skin absorption of the solute after topical application. Skin permeation experiments were performed using Franz diffusion cells and human epidermal membrane (HEM). Radiolabeled corticosterone ((3)H-CS) was the model permeant. The solvents used had different evaporation and skin penetration properties that were expected to impact skin deposition of CS and its absorption across skin. The results show no correlation between the rate of absorption of the permeant and the rate of solvent evaporation/penetration with ethanol, hexane, isopropanol, and butanol as the solvent; all of these solvents have fast evaporation rates (complete evaporation in <30 min after application). This suggests no differences in solvent-induced deposition of CS in the SC for the fast-evaporating solvents. The results of these fast-evaporating solvents were different from those of water, propylene glycol, and polyethylene glycol 400, that a relationship between permeant absorption and the rate of solvent evaporation was observed. PMID:25261711

  8. Gas in scattering media absorption spectroscopy - GASMAS

    NASA Astrophysics Data System (ADS)

    Svanberg, Sune

    2008-09-01

    An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. GASMAS combines narrow-band diode-laser spectroscopy with diffuse media optical propagation. While solids and liquids have broad absorption features, free gas in pores and cavities in the material is characterized by sharp spectral signatures, typically 10,000 times sharper than those of the host material. Many applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, allowing propagation. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities have been studied. Transport of gas in porous media can readily be studied by first immersing the material in, e.g., pure nitrogen, and then observing the rate at which normal air, containing oxygen, reinvades the material. The conductance of the sinus connective passages can be measured in this way by flushing the nasal cavity with nitrogen. Also other dynamic processes such as drying of materials can be studied. The techniques have also been extended to remote-sensing applications (LIDAR-GASMAS).

  9. Intestinal absorption of biotin in the rat

    SciTech Connect

    Bowman, B.B.; Selhub, J.; Rosenberg, I.H.

    1986-07-01

    We examined the absorption of biotin using the in vivo intestinal loop technique. Jejunal segments from male rats were filled with solutions containing (/sup 3/H)biotin and (/sup 14/C)inulin in Krebs-Ringer phosphate buffer, pH 6.5. Absorption was determined on the basis of luminal tritium disappearance after correction for inulin recovery. At biotin concentrations of 0.1 and 5.0 microM, luminal biotin disappearance was linear for at least 10 min. At biotin concentrations ranging from 2.3 nM to 75 microM, 10-28% of the administered dose was absorbed in 10 min. The concentration dependence of luminal biotin disappearance is consistent with the presence of both saturable and nonsaturable (linear) components of biotin uptake, with estimated Km = 9.6 microM and Jmax = 75.2 pmol/(2.5 cm loop X min). The rate constant for nonsaturable uptake is 3.1 pmol/(2.5 cm loop X min X microM). We conclude that at biotin concentrations less than 5 microM, biotin absorption proceeds largely by the saturable process, whereas at concentrations above 25 microM, nonsaturable uptake predominates. Additional studies demonstrated significantly less biotin uptake in the ileum than in the jejunum, a finding in agreement with previous in vitro studies.

  10. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Tim Fout

    2007-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer is used for the increase of absorption rate, and plays the role of transportation of CO{sub 2}. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the

  11. Incomplete intestinal absorption of fructose.

    PubMed

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-08-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children.

  12. Incomplete intestinal absorption of fructose.

    PubMed Central

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-01-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children. PMID:6476870

  13. Gastrointestinal absorption of uranium compounds--a review.

    PubMed

    Konietzka, Rainer

    2015-02-01

    Uranium occurs naturally in soil and rocks, and therefore where it is present in water-soluble form it also occurs naturally in groundwater as well as in drinking water obtained from groundwater. Animal studies suggest that the toxicity of uranium is mainly due to its damage to kidney tubular cells following exposure to soluble uranium compounds. The assessments of the absorption of uranium via the gastrointestinal tract vary, and this has consequences for regulation, in particular the derivation of e.g. drinking water limit values. Absorption rates vary according to the nature and solubility of the compound in which uranium is presented to the test animals and depending on the animal species used in the test. No differences for sex have been observed for absorption in either animals or humans. However, human biomonitoring data do show that boys excrete significantly more uranium than girls. In animal studies neonates took up more uranium than adults or older children. Nutritional status, and in particular the iron content of the diet, have a marked influence on absorption, and higher uranium levels in food intake also appear to increase the absorption rate. If the pointers to an absorption mechanism competing with iron are correct, these mechanisms could also explain the relatively high concentration and chemical toxicity of uranium in the kidneys. It is here (and in the duodenum) that divalent metal transporter 1 (DMT1), which is primarily responsible for the passage of iron (or uranium?) through the cell membranes, is most strongly expressed.

  14. Modulation of ganciclovir intestinal absorption in presence of absorption enhancers.

    PubMed

    Shah, Pranav; Jogani, Viral; Mishra, Pushpa; Mishra, Anil Kumar; Bagchi, Tamishraha; Misra, Ambikanandan

    2007-10-01

    The purpose of this investigation was to study the influences of absorption enhancers in increasing oral bioavailability of Ganciclovir (GAN) by assessing the transepithelial permeation across cell monolayers in vitro and bioavailability in rats in vivo. The permeation of GAN across Caco-2 and MDCK cell monolayers in the absence/presence of dimethyl-beta-cyclodextrin (DMbetaCD), chitosan hydrochloride (CH), sodium lauryl sulphate (SLS), and their combinations was studied for a 2-h period. GAN was administered to rats in absence/presence of absorption enhancers and drug contents in plasma were estimated. We found that the apparent permeability coefficient (Papp) of GAN in absence of absorption enhancers (control) were 0.261 +/- 0.072 x 10(-6) and 0.486 +/- 0.063 x 10(-6) cm/s in Caco-2 and MDCK cell monolayers, respectively, whereas in the presence of DMbetaCD, CH, SLS, and their combinations, Papp of GAN increased by 5- to 25-fold and 7- to 33-fold as compared to control in Caco-2 and MDCK cell monolayers, respectively. However, in rats, the maximum enhancement in bioavailability of GAN during coadministration of these absorption enhancers was only fivefold compared to GAN control. To conclude, the absorption enhancers-DMbetaCD, CH, SLS, and their combinations demonstrated significant improvement in transepithelial permeation and bioavailability of GAN.

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

    PubMed

    Jeong, Cheol-Ho

    2013-06-01

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

  16. Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

    PubMed

    Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-04-01

    The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption.

  17. High-intensity laser heating in liquids: Multiphoton absorption

    SciTech Connect

    Longtin, J.P.; Tien, C.L.

    1995-12-31

    At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in absorption and heating several orders of magnitude greater than classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for strong, controlled energy deposition in liquids without bulk plasma formation, shock waves, liquid ejection, etc., which is of interest for many laser-liquid applications, including laser desorption of liquid films, laser particle removal, and laser water removal from microdevices. This work develops a microscopically based model of the heating during multiphoton absorption in liquids. The dependence on pulse duration, intensity, wavelength, repetition rate, and liquid properties is discussed. Pure water exposed to 266 nm laser radiation is investigated, and a novel heating mechanism for water is proposed that uses multiple-wavelength laser pulses.

  18. "Stirred, Not Shaken": Vibrational Coherence Can Speed Up Electronic Absorption.

    PubMed

    Chang, Bo Y; Shin, Seokmin; Sola, Ignacio R

    2015-08-27

    We have recently proposed a laser control scheme for ultrafast absorption in multilevel systems by parallel transfer (J. Phys. Chem. Lett. 2015, 6, 1724). In this work we develop an analytical model that better takes into account the main features of electronic absorption in molecules. We show that the initial vibrational coherence in the ground electronic state can be used to greatly enhance the rate and yield of absorption when ultrashort pulses are used, provided that the phases of the coherences are taken into account. On the contrary, the initial coherence plays no role in the opposite limit, when a single long pulse drives the optical transition. The theory is tested by numerical simulations in the first absorption band of Na2.

  19. [The absorption and metabolism of oxymatrine in rat intestine].

    PubMed

    Cai, Li-yun; Wu, Li-li; Yu, Xiao-ming; Liu, Jun-jin; Han, Wei-chao; Wei, Qiang; Tang, Lan

    2015-10-01

    The purpose of this study is to systematically investigate the characteristics of absorption and metabolism of oxymatrine (OMT) using rat intestinal perfusion model. Ultra performance liquid chromatography (UPLC) and high performance liquid chromatography-electrospray ionization-quadrupole-time of flight mass spectrometry (HPLC-ESI(+)-Q-TOF-MS) were used to test absorption of OMT in intestine at 100, 200 and 400 µmol · L(-1). The absorption rate and permeability of OMT is not dependent on concentration, but through passive absorption in intestine (P > 0.05). In the rat intestine, the absorbed amount of OMT was significantly different in four sections of the intestine in an order of duodenum > jejunum > ileum > colon (P < 0.05). OMT is metabolized into two metabolites in duodenum and jejunum, and matrine (MT) is the major one.

  20. Electronic structure and optic absorption of phosphorene under strain

    NASA Astrophysics Data System (ADS)

    Duan, Houjian; Yang, Mou; Wang, Ruiqiang

    2016-07-01

    We studied the electronic structure and optic absorption of phosphorene (monolayer of black phosphorus) under strain. Strain was found to be a powerful tool for the band structure engineering. The in-plane strain in armchair or zigzag direction changes the effective mass components along both directions, while the vertical strain only has significant effect on the effective mass in the armchair direction. The band gap is narrowed by compressive in-plane strain and tensile vertical strain. Under certain strain configurations, the gap is closed and the energy band evolves to the semi-Dirac type: the dispersion is linear in the armchair direction and is gapless quadratic in the zigzag direction. The band-edge optic absorption is completely polarized along the armchair direction, and the polarization rate is reduced when the photon energy increases. Strain not only changes the absorption edge (the smallest photon energy for electron transition), but also the absorption polarization.

  1. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Time dependence of absorption voltages (Vabs) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on Vabs, cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on Vabs, are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks. Index Terms: Ceramic capacitor, insulation resistance, dielectric absorption, cracking.

  2. Gastric, intestinal and colonic absorption of a series of beta-blockers in the rat.

    PubMed

    Vilà, J I; Calpena, A C; Obach, R; Domenech, J

    1992-08-01

    Gastric, intestinal and colonic absorption rates of a series of eleven beta-blockers (alprenolol hydrochloride, atenolol, bunolol hydrochloride, penbutolol sulphate, pronethalol hydrochloride, metoprolol, oxprenolol, bevantolol, bufuralol, propranolol hydrochloride and timolol maleate) were estimated using Doluisio's method. The gastric absorption rate was very low and the absorption rate constant could not be assessed accurately in all cases. In the small intestine, the absorption rate constants, Ka, at pH 6.2 ranged between 0.38 h-1 for atenolol and 4.28 h-1 for penbutolol. In the colon, the rate of drug absorption at pH 7.5 ranged between 0.12 h-1 for atenolol and 2.15 h-1 for penbutolol. In most cases, colonic absorption rate constants were of the same order as those obtained in the small intestine, demonstrating the good penetrability through colonic membrane of the series studied. The relationship between absorption rate constants found in the small intestine and colon and the partition constant ([1/Rf]-1), was studied for this non-homologous series of beta-blocker drugs. In both cases, the functional hyperbolic absorption model proposed by Wagner and Sedman [1973] was the most representative.

  3. Mechanisms of intestinal absorption of the carcinogen MNNG (N-Methyl-N'-nitro-N-nitrosoguanidine)

    SciTech Connect

    Koyama, S.Y.; Hollander, D.; Dadufalza, V.

    1988-06-01

    The authors studied the characteristics and mechanisms of MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) intestinal absorption and the interaction between bile acids and fatty acids and MNNG absorption rat in vivo in male Sprague-Dawley rats. They found that MNNG was absorbed by simple passive diffusion. Transport of MNNG was the highest at pH 6.0. The addition of the bile salt, taurocholate by itself, greatly increased MNNG absorption, while the addition of the long-chain unsaturated fatty acids, oleic and linoleic, decreased the rate of absorption of MNNG. The phospholipid lecithin addition to the perfusate did not change the rate of MNNG absorption. Induction of dietary vitamin A deficiency (serum vitamin A level decreased from 40.9 to 13.7 ..mu..g/dl) did not change the absorption rate of MNNG. These studies demonstrate that bile acids, dietary fatty acids, and the pH of the intestinal content can modify the rate of absorption of this carcinogen by the small intestine. Since initial intestinal absorption determines serum levels and subsequent reabsorption and enterohepatic cycling determines long-term lumenal levels, serum levels, and total body content, factors which modify the rate of intestinal absorption of MNNG could also modify its carcinogenicity.

  4. Intestinal absorption of berberine and 8-hydroxy dihydroberberine and their effects on sugar absorption in rat small intestine.

    PubMed

    Wei, Shi-chao; Dong, Su; Xu, Li-jun; Zhang, Chen-yu

    2014-04-01

    The intestinal absorption of berberine (Ber) and its structural modified compound 8-hydroxy dihydroberberine (Hdber) was compared, and their effects on the intestinal absorption of sugar by perfusion experiment were investigated in order to reveal the mechanism of low dose and high activity of Hdber in the treatment of hyperglycemia. The absorption of Hdber and Ber in rat small intestine was measured by in situ perfusion. High performance liquid chromatography (HPLC) was used to determine the concentrations of Hdber and Ber. In situ perfusion method was also used to study the effects of Hdber and Ber on sugar intestinal absorption. Glucose oxidase method and UV spectrophotometry were applied to examine the concentrations of glucose and sucrose in the perfusion fluid. The results showed that the absorption rate of Ber in the small intestine was lower than 10%, but that of Hdber was larger than 70%. Both Hdber and Ber inhibited the absorption of glucose and sucrose at the doses of 10 and 20 μg/mL. However, Hdber presented stronger activity than Ber (P<0.01). It is suggested that Hdber is absorbed easily in rat small intestine and that its inhibitory effect on the absorption of sugar is better than Ber.

  5. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Liang Hu

    2006-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer (transportation layer phase) is used for the increase of absorption rate. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the liquid mass transfer

  6. Sound absorption in metallic foams

    NASA Astrophysics Data System (ADS)

    Lu, T. J.; Hess, Audrey; Ashby, M. F.

    1999-06-01

    The sound absorption capacity of one type of aluminum alloy foams—trade name Alporas—is studied experimentally. The foam in its as-received cast form contains closed porosities, and hence does not absorb sound well. To make the foam more transparent to air motion, techniques based on either rolling or hole drilling are used. Under rolling, the faces of some of the cells break to form small sharp-edged cracks as observed from a scanning electronic microscope. These cracks become passage ways for the in-and-out movement of air particles, resulting in sound absorption improvement. The best performance is nevertheless achieved via hole drilling where nearly all of the sound can be absorbed at selected frequencies. Combining rolling with hole drilling does not appear to lend additional benefits for sound absorption. Image analysis is carried out to characterize the changes in cell morphologies due to rolling/compression, and the drop in elastic modulus due to the formation of cracks is recorded. The effects of varying the relative foam density and panel thickness on sound absorption are measured, and optimal relative density and thickness of the panel are identified. Analytical models are used to explain the measured increase in sound absorption due to rolling and/or drilling. Sound absorbed by viscous flow across small cracks appears to dominate over that dissipated via other mechanisms.

  7. [Study on intestinal absorption of ingredients from different compatibilities of Shaoyao Gancao decoction].

    PubMed

    Ma, Ting-ting; He, Rui; Gong, Mu-xin; Xu, Yong-song; Li, Jing; Zhai, Yong-song; Wan, Guang

    2015-11-01

    To study the compatible mechanisms and compatible proportion of Shaoyao Gancao decoction, the intestinal absorption of main ingredients in Shaoyao Gancao decoction SG11 (Baishao-Zhigancao 1: 1) , SG31 (Baishao-Zhigancao 3: 1), Baishao water decoction S and Zhigancao (G) were investigated and compared using in vitro everted intestinal sac model and in situ single pass intestinal perfusion (SPIP) model. The concentration of paeoniflorin (PF), liquiritin (LQ) and mono-ammonium glycyrrhizinate (GL) in test samples and samples of intestinal sac and intestinal perfusion was determined by HPLC. The intestinal absorptive amount and absorption parameters were calculated. Results showed that in the everted intestinal sac model, three ingredients could be absorbed by duodenum, jejunum and ileum, and the absorption in the jejunum was best for all 3 ingredients. The absorption rate of three ingredients in SG11 was significantly higher than that in single decoction (P < 0.05), but had no significant difference compared with SG31. In SPIP model, the absorption rate constant K(a), the apparent absorption coefficient P(app) and the absorption rate of three ingredients in SG11 were significantly higher than those in single decoction. Parameters of PF and GL in SG11 were significantly higher than those in SG31, but had no differences of LQ. It proved that the compatibility of Baishao and Zhigancao could improve the intestinal absorption of PF, LQ and GL. The absorption of each ingredient in SG11 was better than that in SG31.

  8. Absorption heat pump for space applications

    NASA Technical Reports Server (NTRS)

    Nguyen, Tuan; Simon, William E.; Warrier, Gopinath R.; Woramontri, Woranun

    1993-01-01

    In the first part, the performance of the Absorption Heat Pump (AHP) with water-sulfuric acid and water-magnesium chloride as two new refrigerant-absorbent fluid pairs was investigated. A model was proposed for the analysis of the new working pairs in a heat pump system, subject to different temperature lifts. Computer codes were developed to calculate the Coefficient of Performance (COP) of the system with the thermodynamic properties of the working fluids obtained from the literature. The study shows the potential of water-sulfuric acid as a satisfactory replacement for water-lithium bromide in the targeted temperature range. The performance of the AHP using water-magnesium chloride as refrigerant-absorbent pair does not compare well with those obtained using water-lithium bromide. The second part concentrated on the design and testing of a simple ElectroHydrodynamic (EHD) Pump. A theoretical design model based on continuum electromechanics was analyzed to predict the performance characteristics of the EHD pump to circulate the fluid in the absorption heat pump. A numerical method of solving the governing equations was established to predict the velocity profile, pressure - flow rate relationship and efficiency of the pump. The predicted operational characteristics of the EHD pump is comparable to that of turbomachinery hardware; however, the overall efficiency of the electromagnetic pump is much lower. An experimental investigation to verify the numerical results was conducted. The pressure - flow rate performance characteristics and overall efficiency of the pump obtained experimentally agree well with the theoretical model.

  9. Absorption characteristics of lithium bromide (LiBr) solution constrained by superhydrophobic nanofibrous structures

    SciTech Connect

    Isfahani, RN; Moghaddam, S

    2013-08-01

    An experimental study on absorption characteristics of water vapor into a thin lithium bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure, cooling surface temperature, solution film thickness, and solution flow velocity on the absorption rate are studied. An absorption rate of approximately 0.006 kg/m(2) s was measured at a LiBr solution channel thickness and flow velocity of 100 mu m and 5 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the test conditions of this study. It was demonstrated that decreasing the solution film thickness and increasing the solution velocity enhance the absorption rate. The high absorption rate and the inherently compact form of the proposed,absorber facilitate development of compact small-scale waste heat or solar-thermal driven cooling systems. Published by Elsevier Ltd.

  10. Nitrogen dioxide absorption in aqueous sodium sulfite

    NASA Astrophysics Data System (ADS)

    Shen, Chen Hua

    The Clean Air Act of 1990 requires additional reduction of acid gases, sulfur dioxide, and nitrogen oxides released into the atmosphere from coal-fired electric power plants. In the case of older existing power plants, a possible retrofit strategy is to oxidize nitric oxide (NO, the major constituent of NOsbX in flue gas) to nitrogen dioxide (NOsb2) by the addition of methanol or other hydrocarbons into the duct at an optimum temperature regime. NOsb2 can then be removed by either modifying existing SOsb2 control equipment or by adding a limestone (CaCOsb3) slurry scrubbing process. Limestone reacts with SOsb2 to from CaSOsb3, and the free sulfite (SO{sb3sp{=}}) in the solution is reactive toward NOsb2. The focus of this research is to study the reaction between NOsb2 and aqueous sulfite at elevated temperature and in the presence of gas phase Osb2. The removal of NOsb2 by limestone slurry scrubbing involves the reaction between NOsb2 and SO{sb3sp{=}}, bisulfite (HSO{sb3sp{-}}) and water. The reactions between NOsb2 and SO{sb3sp{=}}/HSO{sb3sp{-}} are first order in both reactants, while the NOsb2-water reaction is second order in NOsb2 concentration. The rate constants of the above reactions and the NOsb2-thiosulfate (Ssb2O{sb3sp{=}}) reaction were determined at 55sp°C. SO{sb3sp{=}} was found to be the most reactive toward NOsb2, while the contribution of chemical reaction still dominated in the absorption of NOsb2 into water. The effect of gas phase SOsb2 and Osb2, and liquid phase additives such as Ssb2O{sb3sp{=}}, Casp{++}, Mgsp{++}, and Clsp{-} on NOsb2 absorption was also investigated. The absorption of NOsb2 catalyzes free radical reactions that lead to sulfite oxidation. A semi-empirical model was proposed to relate the rate of sulfite oxidation to the rate of NOsb2 absorption. Thiosulfate inhibits sulfite oxidation by providing an alternative route for the termination of the free radical reactions, and a fundamental model was derived to quantify the effect

  11. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  12. Diabetic lipohypertrophy delays insulin absorption.

    PubMed

    Young, R J; Hannan, W J; Frier, B M; Steel, J M; Duncan, L J

    1984-01-01

    The effect of lipohypertrophy at injection sites on insulin absorption has been studied in 12 insulin-dependent diabetic patients. The clearance of 125I-insulin from sites with lipohypertrophy was significantly slower than from complementary nonhypertrophied sites (% clearance in 3 h, 43.8 +/- 3.5 +/- SEM) control; 35.3 +/- 3.9 lipohypertrophy, P less than 0.05). The degree of the effect was variable but sufficient in several patients to be of clinical importance. Injection-site lipohypertrophy is another factor that modifies the absorption of subcutaneously injected insulin.

  13. Solar powered absorption air conditioning

    NASA Astrophysics Data System (ADS)

    Vardon, J. M.

    1980-04-01

    Artificial means of providing or removing heat from the building are discussed along with the problem of the appropriate building design and construction for a suitable heat climate inside the building. The use of a lithium bromide-water absorption chiller, powered by a hot water store heated by an array of stationary flat collectors, is analyzed. An iterative method of predicting the cooling output from a LiBr-water absorption refrigeration plant having variable heat input is described and a model allowing investigation of the performance of a solar collector and thermal storage system is developed.

  14. Computational oral absorption simulation for low-solubility compounds.

    PubMed

    Sugano, Kiyohiko

    2009-11-01

    Bile micelles play an important role in oral absorption of low-solubility compounds. Bile micelles can affect solubility, dissolution rate, and permeability. For the pH-solubility profile in bile micelles, the Henderson-Hasselbalch equation should be modified to take bile-micelle partition into account. For the dissolution rate, in the Nernst-Brunner equation, the effective diffusion coefficient in bile-micelle media should be used instead of the monomer diffusion coefficient. The diffusion coefficient of bile micelles is 8- to 18-fold smaller than that of monomer molecules. For permeability, the effective diffusion coefficient in the unstirred water layer adjacent to the epithelial membrane, and the free fraction at the epithelial membrane surface should be taken into account. The importance of these aspects is demonstrated here using several in vivo and clinical oral-absorption data of low-solubility model compounds. Using the theoretical equations, the food effect on oral absorption is further discussed.

  15. 78 FR 61378 - 60 Day Notice of Proposed Information Collection for Public Comment: Survey of Market Absorption...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-03

    ... Absorption of New Multifamily Units AGENCY: Office of Policy Development and Research, HUD. ACTION: Notice... Absorption of New Multifamily Units. OMB Control Number: 2528-0013 (Expires 5/31/2014). Form Number: H-31... Survey of Market Absorption (SOMA) provides the data necessary to measure the rate at which new...

  16. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect

    Mcgrane, Shawn D; Dang, Nhan C; Whitley, Von H; Bolome, Cindy A; Moore, D S

    2010-01-01

    Transient absorption spectra from 390-890 nm of laser shocked RDX, PETN, sapphire, and polyvinylnitrate (PVN) at sub-nanosecond time scales are reported. RDX shows a nearly linear increase in absorption with time after shock at {approx}23 GPa. PETN is similar, but with smaller total absorption. A broad visible absorption in sapphire begins nearly immediately upon shock loading but does not build over time. PVN exhibits thin film interference in the absorption spectra along with increased absorption with time. The absorptions in RDX and PETN are suggested to originate in chemical reactions happening on picosecond time scales at these shock stresses, although further diagnostics are required to prove this interpretation.

  17. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  18. Proposed human stratum corneum water domain in chemical absorption.

    PubMed

    Zhu, Hanjiang; Jung, Eui-Chang; Hui, Xiaoying; Maibach, Howard

    2016-08-01

    Compounds with varying physical and chemical properties may have different affinities to the stratum corneum (SC) and/or its intercellular lipids, keratin protein, and possible water domains. To better understand the mechanism of percutaneous absorption, we utilized 21 carbon-14 labeled chemicals, with wide hydrophilicity (log P = -0.05 to 6.17), and quantified their absorption/adsorption properties for a short incubation time (15 min) with regards to intact SC membrane, delipidized SC membrane and SC lipid. A facile method was developed for SC/lipid absorption, providing a more equivalent procedure and comparable data. SC lipid absorption of chemical solutes positively correlated with the octanol/water partition coefficient (log P). Differences between the percent dose of chemical absorption to intact SC and the total percent dose contributed by the protein and lipid domains suggest the possibility and significance of a water domain. Absorption rate experiments showed a longer lag time for intact SC than for delipidized SC or SC lipid, suggesting that the water domain may delay chemical binding to protein and lipid domains, and may be a factor in the resistance of many chemicals to current decontamination methods. Copyright © 2015 John Wiley & Sons, Ltd.

  19. Concentration-modulated absorption spectroscopy.

    PubMed

    Langley, A J; Beaman, R A; Baran, J; Davies, A N; Jones, W J

    1985-07-01

    Concentration modulation is demonstrated to be a technique capable of markedly extending sensitivity limits in absorption spectroscopy. The gain generated relates in such a manner to sample transmittance that for the first reported time direct spectroscopic concentration measurements become possible. When concentration modulation is used with picosecond lasers, state lifetimes can be determined to a limit of approximately 20 psec.

  20. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  1. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process."

  2. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process." PMID:12285766

  3. Phenoxyethanol absorption by polyvinyl chloride.

    PubMed

    Lee, M G

    1984-12-01

    Phenoxyethanol was found to be absorbed by polyvinyl chloride administration sets during continuous irrigation therapy. Depending upon the conditions of administration up to 20% loss of potency could occur. Absorption of the drug by the rigid plastic luer-lock fitting of the set caused softening and decreased rigidity of the plastic.

  4. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

    Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er3+:Y2SiO5, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained.

  5. Methods for deacidizing gaseous mixtures by phase enhanced absorption

    DOEpatents

    Hu, Liang

    2012-11-27

    An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

  6. Is oral absorption of vigabatrin carrier-mediated?

    PubMed

    Nøhr, M K; Juul, R V; Thale, Z I; Holm, R; Kreilgaard, M; Nielsen, C U

    2015-03-10

    The aim of the study was to investigate the intestinal transport mechanisms responsible for vigabatrin absorption in rats by developing a population pharmacokinetic (PK) model of vigabatrin oral absorption. The PK model was used to investigate whether vigabatrin absorption was carrier-mediated and if the proton-coupled amino acid transporter 1 (PAT1) was involved in the absorption processes. Vigabatrin (0.3-300mg/kg) was administered orally or intravenously to Sprague Dawley rats in the absence or presence of PAT1-ligands l-proline, l-tryptophan or sarcosine. The PK profiles of vigabatrin were described by mechanistic non-linear mixed effects modelling, evaluating PAT1-ligands as covariates on the PK parameters with a full covariate modelling approach. The oral absorption of vigabatrin was adequately described by a Michaelis-Menten type saturable absorption. Using a Michaelis constant of 32.8mM, the model estimated a maximal oral absorption rate (Vmax) of 64.6mmol/min and dose-dependent bioavailability with a maximum of 60.9%. Bioavailability was 58.5-60.8% at 0.3-30mg/kg doses, but decreased to 46.8% at 300mg/kg. Changes in oral vigabatrin PK after co-administration with PAT1-ligands was explained by significant increases in the apparent Michaelis constant. Based on the mechanistic model, a high capacity low affinity carrier is proposed to be involved in intestinal vigabatrin absorption. PAT1-ligands increased the Michaelis constant of vigabatrin after oral co-administration indicating that this carrier could be PAT1.

  7. Nitrogen enrichment of surface water by absorption of ammonia volatilized from cattle feedlots.

    PubMed

    Hutchinson, G L; Viets, F G

    1969-10-24

    Apparatus designed to measure absorption of ammonia from the air by aqueous surfaces was installed near several cattle feedlots and in appropriate control areas. Ammonia absorption rates measured near feedlots were as much as 20 times greater than near the control. Their magnitudes indicate that absorption of ammonia volatilized from cattle feedlots contributes significantly to the nitrogen enrichment of surface water in the vicinity of feedlots.

  8. Dynamic Absorption Model for Off-Gas Separation

    SciTech Connect

    Veronica J. Rutledge

    2011-07-01

    Modeling and simulations will aid in the future design of U.S. advanced reprocessing plants for the recovery and recycle of actinides in used nuclear fuel. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, a rate based, dynamic absorption model is being developed in gPROMS software. Inputs include liquid and gas stream constituents, column properties, liquid and gas phase reactions, number of stages, and inlet conditions. It simulates multiple component absorption with countercurrent flow and accounts for absorption by mass transfer and chemical reaction. The assumption of each stage being a discrete well-mixed entity was made. Therefore, the model is solved stagewise. The simulation outputs component concentrations in both phases as a function of time from which the rate of absorption is determined. Temperature of both phases is output as a function of time also. The model will be used able to be used as a standalone model in addition to in series with other off-gas separation unit operations. The current model is being generated based on NOx absorption; however, a future goal is to develop a CO2 specific model. The model will have the capability to be modified for additional absorption systems. The off-gas models, both adsorption and absorption, will be made available via the server or web for evaluation by customers.

  9. Dynamic energy absorption characteristics of hollow microlattice structures

    SciTech Connect

    Liu, YL; Schaedler, TA; Chen, X

    2014-10-01

    Hollow microlattice structures are promising candidates for advanced energy absorption and their characteristics under dynamic crushing are explored. The energy absorption can be significantly enhanced by inertial stabilization, shock wave effect and strain rate hardening effect. In this paper we combine theoretical analysis and comprehensive finite element method simulation to decouple the three effects, and then obtain a simple model to predict the overall dynamic effects of hollow microlattice structures. Inertial stabilization originates from the suppression of sudden crushing of the microlattice and its contribution scales with the crushing speed, v. Shock wave effect comes from the discontinuity across the plastic shock wave front during dynamic loading and its contribution scales with e. The strain rate effect increases the effective yield strength upon dynamic deformation and increases the energy absorption density. A mechanism map is established that illustrates the dominance of these three dynamic effects at a range of crushing speeds. Compared with quasi-static loading, the energy absorption capacity a dynamic loading of 250 m/s can be enhanced by an order of magnitude. The study may shed useful insight on designing and optimizing the energy absorption performance of hollow microlattice structures under various dynamic loads. (C) 2014 Elsevier Ltd. All rights reserved.

  10. [Absorption characteristics of molybdenum by reed and cattail].

    PubMed

    Lian, Jian-Jun; Xu, Shi-Guo; Han, Cheng-Wei

    2011-11-01

    The adsorption characteristics of reed and cattail to molybdenum were studied. The toxicity, removal rate, adsorption process and accumulation of Mo were investigated in the short-term indoor-culture experiment. The effects of Mo adsorbed by two plants in nutrition solution with different concentrations were also studied. Due to the Mo toxicity, the color of stems and leaves of two plants had become scorch and the transpiration was declined. The cattail illustrated higher tolerance to Mo than reed when Mo concentration was in the range of 2-20 mg x L(-1). The removal rate of Mo by cattail was 87%, which was higher than reed (62%) with Mo concentration of 2 mg x L(-1). The absorption process of Mo by two plants was homeostasis, and the passivity absorption was the main absorption mechanism. Mo enrichment amount in cattail was higher than that in reed, and Mo concentration in shoot were higher than that in roots. The results displayed that cattail was Mo hyper accumulator. The absorption of Mo was not enhanced with the increase of nutrition solution concentration, due to the competition of other ions. The study suggested that the absorption capacity of Mo was significant by the two plants, and cattail was better for Mo removal than reed.

  11. Lymph capillary pressure of rat intestinal villi during fluid absorption.

    PubMed

    Lee, J S

    1979-09-01

    A newly developed intestinal preparation is described for determining lymph capillary pressure (PL) in the villi in vivo and in vitro. Determination of PL provided an estimate of tissue fluid pressure in the villi. PL was related to the fluid absorption rate and increased by lymphatic obstruction. During fluid absorption from isotonic mucosal fluid, PL was 1.4 +/- 0.5 or 1.1 +/- 0.4 cmH2O determined in vivo or in vitro, respectively. Both pressures were essentially in the same range as that (0.7 +/- 0.3--1.3 +/- 0.5 cmH2O) in which the mucosal fluid was isotonic Na2SO4 solution or Na-free solutions from which little fluid absorption occurred. This range of pressures may be taken as the normal tissue fluid pressure in the villi. At a high rate of fluid absorption from hypotonic mucosal fluid, PL increased to 5.2 +/- 1.4 cmH2O and tissue fluid pressure was also similarly increased. It is concluded that the fluid absorptive process by the epithelium could not develop an appreciable hydrostatic pressure in the villus tissue space or in the lymphatics.

  12. Dissolution and absorption modeling: model expansion to simulate the effects of precipitation, water absorption, longitudinally changing intestinal permeability, and controlled release on drug absorption.

    PubMed

    Johnson, Kevin C

    2003-09-01

    A previously described model for simulating drug dissolution, absorption, and pharmacokinetics has been expanded beyond the original application of simulating immediate-release dosage forms to include simulation of drug precipitation, water absorption from the gastrointestinal tract, changing gastrointestinal permeability, disintegration, and controlled-release and dissolution from a GITS-type dosage form. A mathematical description of the model is presented as well as a retrospective analysis of nifedipine to demonstrate the utility of the model. The fourth-order Runge-Kutta numerical method was used to solve the series of coupled differential equations used to simulate the process of dissolution, absorption, and drug disposition. The model was able to simulate the clinically demonstrated effect for drug particle size on nifedipine plasma concentrations for an immediate-release dosage form. Further simulations indicated that drug particle size was less important for a GITS-type dosage form at a release rate of 1.7 mg/hr compared to rate of 17 mg/hr. Hypothetical calculations simulated the potential effect of drug precipitation, water absorption, and changing permeability on drug plasma concentrations. The expanded model increases the utility of a previously described model in providing guidance in drug development and selection.

  13. A diurnal rhythm in the absorption of glucose and water by isolated rat small intestine.

    PubMed

    Fisher, R B; Gardner, M L

    1976-01-01

    1. Glucose and water absorption by isolated small intestine from rats which have had unrestricted access to food is 50-60% higher at night than during the daytime. 2. When the feeding time is restricted to 06.00-09.00 hr G.M.T. glucose and water absorption rates in the period from 3 to 7 hr after withdrawal of food are almost as high as the rates observed at night-time in the animals with unrestricted feeding. 3. These changes in absorption rates appear to be associated with feeding time and not with the pattern of illumination.

  14. Experimental study of neutrino absorption on carbon

    SciTech Connect

    Krakauer, D.A.; Talaga, R.L. ); Allen, R.C.; Chen, H.H.; Hausammann, R.; Lee, W.P.; Mahler, H.J.; Lu, X.Q.; Wang, K.C. ); Bowles, T.J.; Burman, R.L.; Carlini, R.D.; Cochran, D.R.F.; Doe, P.J.; Frank, J.S.; Piasetzky, E.; Potter, M.E.; Sandberg, V.D. )

    1992-05-01

    The process of electron emission from {similar to}30 MeV neutrino absorption on carbon, {sup 12}C({nu}{sub {ital e}},{ital e}{sup {minus}}){sup 12}N, has been observed. The flux-weighted total cross section for the exclusive neutrino-induced nuclear transition {sup 12}C({nu}{sub {ital e}},{ital e}{sup {minus}}){sup 12}N(g.s.) is (1.05{plus minus}0.10(stat){plus minus}0.10(syst)){times}10{sup {minus}41} cm{sup 2}. The measured cross section and angular distribution {ital d}{sigma}/{ital d}{Omega} are in agreement with theoretical estimates. The inclusive {nu}{sub {ital e}} {sup 12}C reaction rate, which accounted for the majority of all neutrino interactions observed in this experiment, was determined from a detailed fit of energy and angular distributions for the observed electrons. The inclusive {sup 12}C({nu}{sub {ital e}},{ital e}{sup {minus}}){ital X} cross section is measured to be (1.41{plus minus}0.23(tot)){times}10{sup {minus}41} cm{sup 2}. An upper limit for the sum of the {sup 13}C({nu}{sub {ital e}},{ital e}{sup {minus}}){ital X}+{sup 27}Al({nu}{sub {ital e}},{ital e}{sup {minus}}){ital X} inclusive absorption cross sections is presented.

  15. AGN Absorption Linked to Host Galaxies

    NASA Astrophysics Data System (ADS)

    Juneau, Stéphanie

    2014-07-01

    Multiwavelength identification of AGN is crucial not only to obtain a more complete census, but also to learn about the physical state of the nuclear activity (obscuration, efficiency, etc.). A panchromatic strategy plays an especially important role when the host galaxies are star-forming. Selecting far-Infrared galaxies at 0.3absorption and the specific star formation rate (sSFR) of the host galaxies, indicating a physical link between X-ray absorption and either the gas fraction or the gas geometry in the hosts. These findings have implications for our current understanding of both the AGN unification model and the nature of the black hole-galaxy connection.

  16. Emission rate measuring device

    NASA Astrophysics Data System (ADS)

    Luckat, S.

    1980-09-01

    The development and application of an emission rate measuring device for gaseous components is explored. The device contains absorption fluid from a supply container that moistens a cylindrical paper sleeve. A newer model is provided with a direct current motor requiring less electricity than an older model. The hose pump is modified to avoid changing it and the filter sleeve is fastened more securely to the distributor head. Application of the measuring devices is discussed, particularly at the Cologne Cathedral, where damage to the stone is observed.

  17. Absorption and emission properties of photonic crystals and metamaterials

    SciTech Connect

    Peng, Lili

    2007-01-01

    We study the emission and absorption properties of photonic crystals and metamaterials using Comsol Multiphysics and Ansoft HFSS as simulation tools. We calculate the emission properties of metallic designs using drude model and the results illustrate that an appropriate termination of the surface of the metallic structure can significantly increase the absorption and therefore the thermal emissivity. We investigate the spontaneous emission rate modifications that occur for emitters inside two-dimensional photonic crystals and find the isotropic and directional emissions with respect to different frequencies as we have expected.

  18. Semidiurnal temperature oscillation and E-region absorption over Haringhata

    NASA Technical Reports Server (NTRS)

    Purkait, N. N.

    1985-01-01

    An attempt has been made to explain the observed asymmetry in the diurnal curves on absorption for the E region at 2.2 MHz for the field station at Haringhata (22 deg 56'N, 88 deg 36'E). A comparison between the computed and observed diurnal curves on absorption revealed that a part of the asymmetry was a manifestation of the effect of semidiurnal temperature oscillation present in the E layer. It was further noted that the degree of the asymmetry of the observed diurnal curves depends profoundly on the rate of downwards phase progression of the temperature oscillation.

  19. Ultraviolet absorption spectrum of chlorine nitrite, ClONO

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Molina, M. J.

    1977-01-01

    The near-ultraviolet absorption spectrum of chlorine nitrite (ClONO) has been quantitatively investigated over the wavelength range 230-400 nm at 231 K. An absorption maximum was observed at 290 nm with a cross section of 1.5 by 10 to the -18th power sq cm. The calculated lifetime against photodissociation for ClONO in the atmosphere is 2 to 3 minutes. The large photolysis rate indicates that ClONO does not play a significant role in the stratosphere as a temporary holding tank for chlorine.

  20. Effect of UV Absorption on Fabrication of Fiber-Optic Bragg Gratings

    NASA Technical Reports Server (NTRS)

    Wang, Ying; Sharma, Anup; Burdine, Robert (Technical Monitor)

    2000-01-01

    UV light is used to fabricate fiber-optic gratings also heats up the fiber due to absorption by either the fiber-buffer, fiber-cladding, doped with titania or a thin coating of paint. Significant enhancement in the rate of grating fabrication is observed due to UV light absorption.

  1. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

    A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

  2. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  3. Ionic regulation of Na absorption in proximal colon: cation inhibition of electroneutral Na absorption

    SciTech Connect

    Sellin, J.H.; De Soignie, R.

    1987-01-01

    Active Na absorption (J/sub net//sup NA/) in rabbit proximal colon in vitro is paradoxically stimulated as (Na) in the bathing media is lowered with constant osmolarity. J/sub m..-->..s//sup Na/ increases almost linearly from 0 to 50 mM (Na)/sub 0/ but then plateaus and actually decreases from 50 to 140 mM (Na)/sub 0/, consistent with inhibition of an active transport process. Both lithium and Na are equally effective inhibitors of J/sub net//sup Na/, whereas choline and mannitol do not block the high rate of J/sub net//sup Na/ observed in decreased (Na)/sub 0/. Either gluconate or proprionate replacement of Cl inhibits J/sub net//sup Na/. J/sub net//sup Na/ at lowered (Na)/sub 0/ is electrically silent and is accompanied by increased Cl absorption; it is inhibited by 10/sup -3/ M amiloride and 10/sup -3/ theophylline but not by 10/sup -4/ M bumetanide. Epinephrine is equally effective at stimulating Na absorption at 50 and 140 mM (Na). Na gradient experiments are consistent with a predominantly serosal effect of the decreased (Na)/sub 0/. These results suggest that 1) Na absorption in rabbit proximal colon in vitro is stimulated by decreased (Na); 2) the effect is cation specific, both Na and Li blocking the stimulatory effect; 3) the transport is mediated by Na-H exchange and is Cl dependent but 4) is under different regulatory mechanisms than the epinephrine-sensitive Na-Cl cotransport previously described in proximal colon. Under the appropriate conditions, proximal colon absorbs Na extremely efficiently. Na-H exchange in this epithelium is cation inhibitable, either directly or by a secondary regulatory process.

  4. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

  5. Continuum Absorption Coefficient of Atoms and Ions

    NASA Technical Reports Server (NTRS)

    Armaly, B. F.

    1979-01-01

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

  6. Weibel instability due to inverse bremsstrahlung absorption

    SciTech Connect

    Bendib, A.; Bendib, K.,; Bendib, A.; Bendib, K.; Sid, A.,; Bendib, K.,

    1997-06-01

    A new Weibel source due to the inverse bremsstrahlung absorption is presented. It has been shown that in homogeneous plasmas, this mechanism may drive strong collisionless Weibel modes with growth rates of order of {gamma}{approximately}10{sup 11}s{sup {minus}1} and negligible group velocities. In the laser-produced plasmas, for short laser wavelengths ({lambda}{sub L}{lt}1{mu}m) and high laser fluxes (I{gt}10{sup 14}W/cm{sup 2}), this Weibel source is most efficient as the ones due to the heat flux and the plasma expansion. The useful scaling law of the convective e-foldings, with respect to the laser and the plasma parameters, is also derived. {copyright} {ital 1997} {ital The American Physical Society}

  7. Absorption of thiamine and nicotinic acid in the rat intestine during fasting and immobilization stress

    NASA Technical Reports Server (NTRS)

    Kirilyuk, O. G.; Khmelevskiy, Y. V.

    1980-01-01

    By perfusion of isolated sections of intestine with a solution containing thiamine at a concentration of 3.1 micromole, it was established that thiamine absorption in animals fasted for 72 hours decreased by 28 percent, whereas absorption increased by 12 percent in rats after 24 hour immobilization. After immobilization, absorption of label in the intestinal mucosa increased. Na K ATPase activity in the intestinal mucosa decreased by 10 percent during fasting, and it increased with immobilization of the animals. Activity of Na K ATPase in the intestinal mucosa cells determined the absorption rate of thiamine and nicotinic acid at the level of vitamin transport through the plasma membranes of the enterocytes.

  8. Rapidly reconfigurable slow-light system based on off-resonant Raman absorption

    NASA Astrophysics Data System (ADS)

    Vudyasetu, Praveen K.; Camacho, Ryan M.; Howell, John C.

    2010-11-01

    We present a slow-light system based on dual Raman absorption resonances in warm rubidium vapor. Each Raman absorption resonance is produced by a control beam in an off-resonant Λ system. This system combines all optical control of the Raman absorption and the low-dispersion broadening properties of the double Lorentzian absorption slow light. The bandwidth, group delay, and central frequency of the slow-light system can all be tuned dynamically by changing the properties of the control beam. We demonstrate multiple pulse delays with low distortion and show that such a system has fast switching dynamics and thus fast reconfiguration rates.

  9. Prediction of the furnace heat absorption by utilizing thermomechanical analysis for various kinds of coal firing

    SciTech Connect

    Ishinomori, T.; Watanabe, S.; Kiga, T.; Wall, T.F.; Gupta, R.P.; Gupta, S.K.

    1999-07-01

    In order to predict the furnace heat absorption, which is sensitive to coal properties, an attempt to make a model universally applicable for any kind of pulverized coal fired boiler is in progress. First of all, the heat absorption rates on to furnace wall were surveyed for 600MWe pulverized coal fired boiler, and they were ranked into four levels by indicating a furnace heat absorption index (FHAI). Some ash composition is relatively well related to the FHAI, while a new index from thermomechanical analysis (TMA) offers a good prediction of the furnace heat absorption.

  10. Thermal properties of carbon black aqueous nanofluids for solar absorption

    PubMed Central

    2011-01-01

    In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency. PMID:21767359

  11. H I absorption toward cooling flows in clusters of galaxies

    NASA Technical Reports Server (NTRS)

    Mcnamara, Brian R.; O'Connell, Robert W.; Bregman, Joel N.

    1990-01-01

    An H I survey of 14 cooling flow clusters and two noncooling flow clusters was conducted, and H I absorption features were detected against the nuclear radio continuum sources of two cooling flow dominant (CFD) galaxies, 2A 0335 + 096 and MKW3s. The absorption features are broad and redshifted with respect to the stellar absorption-line velocity of the CFDs by 90-225 km/s. This indicates that the H I is falling onto, and is probably gravitationally bound to, the CFDs. The kinematics of the H I clouds suggest a possible kinematic link between the warm and cold phases of the intracluster medium. The clouds are orders of magnitude smaller in radius and mass and larger in density than Galactic H I clouds. The detected CFDs have mass-accretion rates that are about 2.5 times larger than the CFDs that were not detected.

  12. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2014-01-01

    Time dependence of absorption voltages (V(sub abs)) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on V(sub abs)), cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on V(sub abs)), are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks.

  13. Absorption-reduced waveguide structure for efficient terahertz generation

    SciTech Connect

    Pálfalvi, L.; Fülöp, J. A.; Hebling, J.

    2015-12-07

    An absorption-reduced planar waveguide structure is proposed for increasing the efficiency of terahertz (THz) pulse generation by optical rectification of femtosecond laser pulses with tilted-pulse-front in highly nonlinear materials with large absorption coefficient. The structure functions as waveguide both for the optical pump and the generated THz radiation. Most of the THz power propagates inside the cladding with low THz absorption, thereby reducing losses and leading to the enhancement of the THz generation efficiency by up to more than one order of magnitude, as compared with a bulk medium. Such a source can be suitable for highly efficient THz pulse generation pumped by low-energy (nJ-μJ) pulses at high (MHz) repetition rates delivered by compact fiber lasers.

  14. Dawn Grand Map Vesta Neutron Absorption V1.0

    NASA Astrophysics Data System (ADS)

    Prettyman, T. H.

    2014-06-01

    A global map of a unitless compositional parameter, delta-C_perpendicular (DCP), and propagated 1-sigma uncertainties is provided. DCP varies linearly with the macroscopic thermal neutron absorption cross section of Vesta's regolith. An equation for converting tabulated DCP values to absorption units is provided in this document. DCP was determined from thermal and epithermal neutron counting rates measured by the NASA Dawn mission's Gamma Ray and Neutron Detector (GRaND) while in low altitude mapping orbit, about 210 km from Vesta's surface. The measurements are representative of Vesta's bulk regolith composition to depths of a few decimeters with a spatial resolution of about 300-km full-width-at-half-maximum of arc length on the surface. The methods used to determine neutron absorption are described by PRETTYMANETAL2013.

  15. Acid gas absorption in aqueous solutions of mixed amines

    SciTech Connect

    Rinker, E.B.; Ashour, S.S.; Sandall, O.C.

    1996-12-31

    A mass transfer model has been developed to describe the rate of absorption (or desorption) of H{sub 2}S and CO{sub 2} in aqueous blends of a tertiary and a secondary or a primary amine. The model is based on penetration theory, and all significant chemical reactions are incorporated in the model. The reactions are taken to be reversible, with reactions involving only a proton transfer considered to be at equilibrium. The particular amines studied in this research were methyldiethanolamine (MDEA), a tertiary amine, and diethanolamine (DEA), a secondary amine. Key physicochemical data needed in the model, such as diffusion coefficients, kinetic rate constants, and gas solubilities, were measured. Experimental absorption rates of CO{sub 2} and H{sub 2}S were measured in a model gas-liquid contacting device and were compared with model predictions. Experiments were carried out for single amine solutions (both MDEA and DEA) and for amine blends.

  16. In vivo measurement of the absorption of strontium in the rumen and small intestine of sheep as an index of calcium absorption capacity.

    PubMed

    Hyde, Michelle L; Fraser, David R

    2014-09-14

    In the present study, a method was developed for determining the alimentary tract Ca absorption capacity of ruminant animals by measuring the absorption rate of Sr after the administration of an oral dose of strontium chloride acting as a tracer analogue of Ca. A close correlation between the absorption rates of the two tracers was observed upon simultaneous administration of an oral dose of stable Sr and radioactive calcium (r 0·98). The Ca absorption capacity of the rumen and small intestine was determined separately by either directing the solution into the rumen or by diverting it into the post-ruminal tract by vasopressin-induced closure of the ruminoreticular groove. The animals were treated with 1α-hydroxyvitamin D3 administered via subcutaneously implanted mini-osmotic pumps. The effect of elevated plasma 1,25-dihydroxycholecalciferol concentrations on the Ca absorption capacity of the alimentary tract was then determined. An increased rate of Sr absorption was observed in both the rumen and small intestine of sheep after treatment, although it is unclear whether the rumen possesses the same vitamin D-dependent Ca absorption pathway as the small intestine.

  17. Absorption of sunlight in the atmosphere of venus.

    PubMed

    Tomasko, M G; Doose, L R; Smith, P H

    1979-07-01

    In this report the fluxes measured by the solar flux radiometer (LSFR) of the Pioneer Venus large probe are compared with calculations for model atmospheres. If the large particles of the middle and lower clouds are assumed to be sulfur, strong, short-wavelength absorption results in a net flux profile significantly different from the LSFR net flux measurements. Models in which the smallest particles are assumed to be sulfur gave flux profiles consistent with the measurements if an additional source of absorption is included in the upper cloud. The narrowband data from 0.590 to 0.665 micrometer indicate an absorption optical depth of about 0.05 below the cloud bottom. The broadband data imply that either this absorption extends over a considerable wavelength interval (as might be the case for dust) or that a very strong absorption band lies on one side of the narrowband filter (as suggested by early Venera 11 and Venera 12 reports). Thermal balance calculations based on the measured visible fluxes indicate high surface temperature for reasonable assumptions of cloud opacity and water vapor abundance. The lapse rate becomes convective within the middle cloud. For water mixing ratios of 2.0 x 10(-4) below the clouds we find a subadiabatic region extending from the cloud bottom to altitudes near 35 kilometers.

  18. Physiologically Based Absorption Modeling for Amorphous Solid Dispersion Formulations.

    PubMed

    Mitra, Amitava; Zhu, Wei; Kesisoglou, Filippos

    2016-09-01

    Amorphous solid dispersion (ASD) formulations are routinely used to enable the delivery of poorly soluble compounds. This type of formulations can enhance bioavailability due to higher kinetic solubility of the drug substance and increased dissolution rate of the formulation, by the virtue of the fact that the drug molecule exists in the formulation in a high energy amorphous state. In this article we report the application of physiologically based absorption models to mechanistically understand the clinical pharmacokinetics of solid dispersion formulations. Three case studies are shown here to cover a wide range of ASD bioperformance in human and modeling to retrospectively understand their in vivo behavior. Case study 1 is an example of fairly linear PK observed with dose escalation and the use of amorphous solubility to predict bioperformance. Case study 2 demonstrates the development of a model that was able to accurately predict the decrease in fraction absorbed (%Fa) with dose escalation thus demonstrating that such model can be used to predict the clinical bioperformance in the scenario where saturation of absorption is observed. Finally, case study 3 shows the development of an absorption model with the intent to describe the observed incomplete and low absorption in clinic with dose escalation. These case studies highlight the utility of physiologically based absorption modeling in gaining a thorough understanding of ASD performance and the critical factors impacting performance to drive design of a robust drug product that would deliver the optimal benefit to the patients. PMID:27442959

  19. Drug gastrointestinal absorption in rat: Strain and gender differences.

    PubMed

    Oltra-Noguera, Davinia; Mangas-Sanjuan, Victor; González-Álvarez, Isabel; Colon-Useche, Sarin; González-Álvarez, Marta; Bermejo, Marival

    2015-10-12

    Predictive animal models of intestinal drug absorption are essential tools in drug development to identify compounds with promising biopharmaceutical properties. In situ perfusion absorption studies are routinely used in the preclinical setting to screen drug candidates. The objective of this work is to explore the differences in magnitude and variability on intestinal absorption associated with rat strain and gender. Metoprolol and Verapamil absorption rate coefficients were determined using the in situ closed loop perfusion model in four strains of rats and in both genders. Strains used were Sprague-Dawley, Wistar-Han, Wistar-Unilever, Long-Evans and CD∗IGS. In the case of Metoprolol only CD∗IGS and Wistar Unilever showed differences between males and females. For Verapamil, Wistar Han and Sprague-Dawley strains do not show differences between male and female rats. That means that in these strains permeability data from male and female could be combined. In male rats, which are commonly used for permeability estimation, there were differences for Metoprolol permeability between Sprague-Dawley (with lower permeability values) and the other strains, while for Verapamil Sprague-Dawley and Wistar-Han showed the lower permeability values. In conclusion, the selection of rat's strain and gender for intestinal absorption experiments is a relevant element during study design and data from different strains may not be always comparable.

  20. Correction to the Beer-Lambert-Bouguer law for optical absorption.

    PubMed

    Abitan, Haim; Bohr, Henrik; Buchhave, Preben

    2008-10-10

    The Beer-Lambert-Bouguer absorption law, known as Beer's law for absorption in an optical medium, is precise only at power densities lower than a few kW. At higher power densities this law fails because it neglects the processes of stimulated emission and spontaneous emission. In previous models that considered those processes, an analytical expression for the absorption law could not be obtained. We show here that by utilizing the Lambert W-function, the two-level energy rate equation model is solved analytically, and this leads into a general absorption law that is exact because it accounts for absorption as well as stimulated and spontaneous emission. The general absorption law reduces to Beer's law at low power densities. A criterion for its application is given along with experimental examples.

  1. Absorption, Creativity, Peak Experiences, Empathy, and Psychoticism.

    ERIC Educational Resources Information Center

    Mathes, Eugene W.; And Others

    Tellegen and Atkinson suggested that the trait of absorption may play a part in meditative skill, creativity, capacity for peak experiences, and empathy. Although the absorption-meditative skill relationship has been confirmed, other predictions have not been tested. Tellegen and Atkinson's Absorption Scale was completed by undergraduates in four…

  2. Effect of absorbable and nonabsorbable sugars on intestinal calcium absorption in humans

    SciTech Connect

    Griessen, M.; Speich, P.V.; Infante, F.; Bartholdi, P.; Cochet, B.; Donath, A.; Courvoisier, B.; Bonjour, J.P.

    1989-03-01

    The effects of glucose, galactose, and lactitol on intestinal calcium absorption and gastric emptying were studied in 9, 8, and 20 healthy subjects, respectively. Calcium absorption was measured by using a double-isotope technique and the kinetic parameters were obtained by a deconvolution method. The gastric emptying rate was determined with /sup 99m/Tc-diethylenetriaminepentaacetic acid and was expressed as the half-time of the emptying curve. Each subject was studied under two conditions: (a) with calcium alone and (b) with calcium plus sugar. Glucose and galactose increased the calcium mean transit time and improved the total fractional calcium absorption by 30% (p less than 0.02). Lactitol decreased the mean rate of absorption (p less than 0.001) and reduced the total fractional calcium absorption by 15% (p less than 0.001). The gastric emptying rate did not appear to influence directly the kinetic parameters of calcium absorption. These results show that both glucose and galactose exert the same stimulatory effect as lactose on calcium absorption in subjects with normal lactase whereas lactitol mimics the effects of lactose in lactase-deficient patients. Thus the absorbability of sugars determines their effect on calcium absorption.

  3. [Absorption of flavonoids from Abelmoschus manihot extract by in situ intestinal perfusion].

    PubMed

    Xue, Cai-fu; Guo, Jian-ming; Qian, Da-wei; Duan, Jin-ao; Shu, Yan

    2011-04-01

    To explore the mechanism of the absorption of flavonoids from Abelmoschus manihot flowers, in situ intestinal recirculation was performed to study the effect of the absorption at different concentrations and different intestinal regions. To evaluate the conditions of the absorption of six flavonoids from Abelmoschus manihot flowers, the concentrations of Abelmoschus manihot in the perfusion solution were determined by HPLC at predesigned time. And we have investigated the inhibitory effect of six flavonoids from Abelmoschus manihot flowers on P-glycoprotein (P-gp) drug efflux pump. The results demonstrated that the absorption rates of flavonoids from Abelmoschus manihot flowers are not significantly different (P > 0.05) at various drug concentrations, the absorption of flavonoids from Abelmoschus manihot flowers is a first-order process with the passive diffusion mechanism. The absorption rates of each of flavonoids are significantly different. The absorption rate of flavonoid glycoside was lower than that of aglycone; the flavonoids from Abelmoschus manihot flowers could be absorbed in all of the intestinal segments. The best parts of intestine to absorb hyperoside and myricetin are jejunum and duodenum, separately. Verapamil could enhance the absorption of isoquercitrin, hyperoside, myricetin and quercetin-3'-O-glucoside by inhibiting P-glycoprotein (P-gp) drug efflux pump.

  4. Intestinal bile secretion promotes drug absorption from lipid colloidal phases via induction of supersaturation.

    PubMed

    Yeap, Yan Yan; Trevaskis, Natalie L; Quach, Tim; Tso, Patrick; Charman, William N; Porter, Christopher J H

    2013-05-01

    The oral bioavailability of poorly water-soluble drugs (PWSD) is often significantly enhanced by coadministration with lipids in food or lipid-based oral formulations. Coadministration with lipids promotes drug solubilization in intestinal mixed micelles and vesicles, however, the mechanism(s) by which PWSD are absorbed from these dispersed phases remain poorly understood. Classically, drug absorption is believed to be a product of the drug concentration in free solution and the apparent permeability across the absorptive membrane. Solubilization in colloidal phases such as mixed micelles increases dissolution rate and total solubilized drug concentrations, but does not directly enhance (and may reduce) the free drug concentration. In the absence of changes to cellular permeability (which is often high for lipophilic, PWSD), significant changes to membrane flux are therefore unexpected. Realizing that increases in effective dissolution rate may be a significant driver of increases in drug absorption for PWSD, we explore here two alternate mechanisms by which membrane flux might also be enhanced: (1) collisional drug absorption where drug is directly transferred from lipid colloidal phases to the absorptive membrane, and (2) supersaturation-enhanced drug absorption where bile mediated dilution of lipid colloidal phases leads to a transient increase in supersaturation, thermodynamic activity and absorption. In the current study, collisional uptake mechanisms did not play a significant role in the absorption of a model PWSD, cinnarizine, from lipid colloidal phases. In contrast, bile-mediated dilution of model intestinal mixed micelles and vesicles led to drug supersaturation. For colloids that were principally micellar, supersaturation was maintained for a period sufficient to promote absorption. In contrast, for primarily vesicular systems, supersaturation resulted in rapid drug precipitation and no increase in drug absorption. This work suggests that ongoing

  5. Advanced regenerative absorption refrigeration cycles

    DOEpatents

    Dao, Kim

    1990-01-01

    Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

  6. Removal of OH Absorption Bands Due to Pyrohydrolysis Reactions in Fluoride-Containing Borosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Kobayashi, Keiji

    1997-05-01

    The purpose of this study is to decrease and to remove OH ions and H2O in borosilicate glasses. Fluoride-containing borosilicate glasses followed by dry-air-bubbling showed the significant decrease of OH absorption bands around 3500 cm-1. The decrease of OH absorption bands was elucidated by the use of pyrohydrolysis reactions in these glasses where fluoride ions react with OH ions or H2O during melting. The rates of the decrease of OH absorption bands substantially depend on high valence cations of fluorides. Particularly, the decrease rates of OH absorption coefficients were in the order of ZrF4-containing glass>AlF3-containing glass>ZnF2-containing glass. ZrF4-containing glass treated by dry-air-bubbling showed a good capability to remove OH absorption band. Fluoride-containing glasses showed the low flow point in comparison with fluoride-free glasses.

  7. Drug absorption in gastrointestinal disease and surgery. Clinical pharmacokinetic and therapeutic implications.

    PubMed

    Gubbins, P O; Bertch, K E

    1991-12-01

    Drug absorption from the gastrointestinal (GI) tract and the impact of GI surgery and disease on drug absorption are discussed. Recommendations are made to manage problems of drug malabsorption. Absorption from the GI tract is a first-order process described by its rate and extent. GI surgery changes the anatomy of the GI tract and alters important variables in the absorption process. In the wake of procedures which diminish small bowel surface area, the extent of absorption of phenytoin, digoxin, cyclosporin, aciclovir, hydrochlorothiazide and certain oral contraceptives is reported to be reduced. The underlying cause of the reduction is unknown. When gastric emptying time or pH are altered by surgery, the rate of drug absorption appears to be reduced. However, it is not clear which variable is more important in determining therapeutic effects. The effects of coeliac and inflammatory bowel diseases on the distribution and clearance of drugs must be considered before attributing abnormal serum concentrations of drugs to malabsorption. GI disease may slow gastric emptying and delay the complete absorption of drugs when their rate of absorption depends on gastric emptying time. Other inflammatory GI diseases such as graft-versus-host disease (GVHD) of the gut, Behçet's syndrome and scleroderma involving the GI tract may directly reduce absorption of drugs such as cyclosporin, amitriptyline, benzodiazepines, anticonvulsants, paracetamol (acetaminophen) and penicillamine. GI diseases which alter gut pH affect the absorption only of drugs with limited water solubility and pH-dependent dissolution such as ketoconazole. Clinicians should be aware of the variable absorption seen after GI disease and surgery and monitor their patients accordingly. PMID:1782738

  8. Carbon Dioxide Absorption Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    2002-01-01

    A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO2 from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO2 gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

  9. NEUTRON ABSORPTION AND SHIELDING DEVICE

    DOEpatents

    Axelrad, I.R.

    1960-06-21

    A neutron absorption and shielding device is described which is adapted for mounting in a radiation shielding wall surrounding a radioactive area through which instrumentation leads and the like may safely pass without permitting gamma or neutron radiation to pass to the exterior. The shielding device comprises a container having at least one nonrectilinear tube or passageway means extending therethrough, which is adapted to contain instrumentation leads or the like, a layer of a substance capable of absorbing gamma rays, and a solid resinous composition adapted to attenuate fast-moving neutrons and capture slow- moving or thermal neutrons.

  10. Effective absorption in cladding-pumped fibers

    NASA Astrophysics Data System (ADS)

    Zervas, Michalis N.; Marshall, Andy; Kim, Jaesun

    2011-02-01

    We investigate experimentally and theoretically the wavelength dependence of the pump absorption along Yb3+-doped fibers, for cladding-pumped single as well as coupled multimode (GTWaveTM) fibers. We show that significant spectral absorption distortions occur along the length with the 976nm absorption peak affected the most. We have developed a novel theoretical approach, based on coupled mode theory, to explain the observed effects. We have also investigated the mode mixing requirements in order to improve the absorption spectral distribution along the increase the overall absorption efficiency and discuss the implications on fiber laser performance.

  11. Absorption of ac fields in amorphous indium-oxide films

    SciTech Connect

    Ovadyahu, Z.

    2014-08-20

    Absorption data from applied ac fields in Anderson-localized amorphous indium-oxide (In{sub x}O) films are shown to be frequency and disorder dependent. The absorption shows a roll-off at a frequency which is much lower than the electron-electron scattering rate of the material when it is in the diffusive regime. This is interpreted as evidence for discreteness of the energy spectrum of the deeply localized regime. This is consistent with recent many-body localization scenarios. As the metal-insulator transition is approached, the absorption shifts to higher frequencies. Comparing with the previously obtained results on the crystalline version of indium-oxide (In{sub 2}O{sub 3−x}) implies a considerably higher inelastic electron-phonon scattering rate in the amorphous material. The range over which the absorption versus frequency decreases may indicate that a wide distribution of localization length is a common feature in these systems.

  12. [Study on transdermal absorption of borneol-salicylic acid eutectic mixture].

    PubMed

    Cui, D X; Sugibayashi, K; Morimoto, Y; Li, F L

    1989-01-01

    Borneol is an organic drug having property to form eutectic mixture with salicylic acid. We compared the transdermal absorption rate of borneol alone with that of borneol-salicylic acid eutectic mixture in hairless rats. The results showed that the borneol-salicylic acid eutectic mixture can evidently increase the absorption rate of borneol and provided a method for manufacturing borneol preparation which can easily be absorbed transdermally.

  13. Infrared absorption mechanisms of black silicon

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengxi; Chen, Yongping; Ma, Bin

    2014-09-01

    Black silicon has a wide spectrum of non-spectral characteristics high absorption from visible to long wave infrared band .Based on semi-empirical impurity band model, free carrier absorption, radiation transitions between the valence band and the impurity band, radiation transitions between the impurity band and the conduction band were calculated, and absorption coefficients for each process were got. The results showed that the transitions from valence band to the impurity band induced absorption in the near-infrared waveband, but it has a rapid decay with wavelength. In the shortwave mid-wave and long-wave IR bands, transitions from the impurity band to the conduction band caused a huge absorption, and the absorption coefficient was slowly decreased with increasing wavelength. The free carrier absorption dominates in long-wave band. The calculation results agreed well with the test results of plant black silicon in magnitude and trends.

  14. On the absorption of drugs using chronic dog ileal loop method.

    PubMed

    Kukan, M; Bezek, S; Trnovec, T; Gabauer, I; Styk, J

    1994-01-01

    The absorption rate of three model drugs, i.e., pentacaine (highly lipophilic), stobadine (moderately lipophilic) and acetylsalicylic acid (hydrophilic), was studied using the chronic dog ileal loop method. The drugs were dissolved either in 0.9% unbuffered solution of NaCl or in antacid mixture. When using 0.9% NaCl, the half-lives of absorption (t1/2 (dis)) of pentacaine and stobadine were (mean +/- SD) 23.2 +/- 7.8 min and 20.8 +/- 7.2 min, respectively. For stobadine a good agreement was found between its t1/2 (dis) from the ileum and its absorption half-life determined from blood concentrations after oral administration to dogs. The absorption of acetylsalicylic acid accounted for only 10-20% of the dose introduced into the loop over 45 min; thus, a reliable value of t1/2 (dis) could not be determined. The administration of unbuffered solution of NaCl into the loop was accompanied by rapid increase of pH from acidic to basic value. The antacid mixture failed to affect the absorption rate of the drugs studied. Sampling from the ileum was limited to 35-55 min due to rapid absorption of water. These results suggest that: 1) measurement of the absorption rate of some drugs, e.g., stobadine, by using the chronic dog ileal loop method may adequately predict their absorption rate after peroral administration to the dog, 2) interactions of antacids with drug absorption in the ileum may not play a significant role because of the strong buffering capacity of the ileum, and 3) rapid absorption of water from the ileum does not allow to reliably determine the value of t1/2 (dis) for slowly absorbed drugs. PMID:7837833

  15. Study on NO2 absorption by ascorbic acid and various chemicals*

    PubMed Central

    Li, Wei; Wu, Cheng-zhi; Fang, He-liang; Shi, Yao; Lei, Le-cheng

    2006-01-01

    Study on NO2 absorption aimed at seeking a better NO2 absorption chemical at pH 4.5~7.0 for application to existing wet flue gas desulfurization (FGD). The results from the double-stirred reactor indicated that ascorbic acid has very high absorption rate at this pH range. The rate constant of ascorbic acid reaction with NO2 (0~1000×10−6 mol/mol) is about 3.54×106 mol/(L·s) at pH 5.4~6.5 at 55 °C. PMID:16365924

  16. Energy absorption of composite materials

    NASA Technical Reports Server (NTRS)

    Farley, G. L.

    1983-01-01

    Results of a study on the energy absorption characteristics of selected composite material systems are presented and the results compared with aluminum. Composite compression tube specimens were fabricated with both tape and woven fabric prepreg using graphite/epoxy (Gr/E), Kevlar (TM)/epoxy (K/E) and glass/epoxy (Gl/E). Chamfering and notching one end of the composite tube specimen reduced the peak load at initial failure without altering the sustained crushing load, and prevented catastrophic failure. Static compression and vertical impact tests were performed on 128 tubes. The results varied significantly as a function of material type and ply orientation. In general, the Gr/E tubes absorbed more energy than the Gl/E or K/E tubes for the same ply orientation. The 0/ + or - 15 Gr/E tubes absorbed more energy than the aluminum tubes. Gr/E and Gl/E tubes failed in a brittle mode and had negligible post crushing integrity, whereas the K/E tubes failed in an accordian buckling mode similar to the aluminum tubes. The energy absorption and post crushing integrity of hybrid composite tubes were not significantly better than that of the single material tubes.

  17. Percutaneous absorption of selenium sulfide

    SciTech Connect

    Farley, J.; Skelly, E.M.; Weber, C.B.

    1986-01-01

    The purpose of this study was to determine selenium levels in the urine of Tinea patients before and after overnight application of a 2.5% selenium sulfide lotion. Selenium was measured by atomic absorption spectroscopy (AAS). Hydride generation and carbon rod atomization were studied. It was concluded from this study that selenium is absorbed through intact skin. Selenium is then excreted, at least partially, in urine, for at least a week following treatment. The data show that absorption and excretion of selenium vary on an individual basis. Selenium levels in urine following a single application of selenium sulfide lotion do not indicate that toxic amounts of selenium are being absorbed. Repeated treatments with SeS/sub 2/ result in selenium concentrations in urine which are significantly higher than normal. Significant matrix effects are observed in the carbon rod atomization of urine samples for selenium determinations, even in the presence of a matrix modifier such as nickel. The method of standard additions is required to obtain accurate results in the direct determination of selenium in urine by carbon rod AAS.

  18. Iron Absorption in Drosophila melanogaster

    PubMed Central

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-01-01

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration. PMID:23686013

  19. Enhancement of Absorption by Micro-Mixing induced by Villi Motion

    NASA Astrophysics Data System (ADS)

    Wang, Yanxing; Brasseur, James; Banco, Gino

    2009-11-01

    Motions of surface villi create microscale flows that can couple with lumen-scale eddies to enhance absorption at the epithelium of the small intestine. Using a multigrid strategy within the lattice-Boltzmann framework, we model a macro-scale cavity flow with microscale ``villi'' in pendular motion on the lower surface and evaluate the couplings between macro and micro-scale fluid motions, scalar mixing, and uptake of passive scalar at the villi surface. We study the influences of pendular frequency, villous length, and villous groupings on absorption rate. The basic mechanism underlying the enhancement of absorption rate by a villous-induced ``micro-mixing layer'' (MML) is the microscale ``pumping'' of low concentration fluid from between groups of villi coupled with the return of high concentration fluid into the villi groups from the macroscale flow. The MML couples with the macrosacle eddies through a diffusion layer that separates micro and macro mixed layers. The absorption rate increases with frequency of villi oscillation due to enhanced vertical pumping. We discover a critical villus length above which absorption rate increases significantly. The absorption is influenced by villus groupings in a complex way due to the interference between vertical and horizontal geometry vs. MML scales. We conclude that optimized villi motility can enhance absorption and may underlie an explanation for the existence of villi in the gut. [Supported by NSF

  20. The influence of food on the oral absorption of bevantolol.

    PubMed

    Toothaker, R D; Randinitis, E J; Nelson, C; Kinkel, A W; Goulet, J R

    1987-04-01

    The bioavailability of bevantolol was compared in 12 healthy volunteers given single doses of the drug as the HCl salt after an overnight fast, or 15 minutes before or after a standardized breakfast in a nonblind, randomized crossover design. Bevantolol was rapidly absorbed in all three treatment groups, with maximum concentrations (Cmax) observed at 1.0, 0.9, and 1.8 hours for the fasting, before breakfast, and after breakfast groups, respectively. Time to Cmax was significantly longer than fasting only when bevantolol was given after breakfast. Food ingestion did not significantly affect Cmax, total of absorbed drug, or the drug elimination rate. Since food only slightly decreases the drug absorption rate and has no measurable effect on the extent of drug absorption, the relationship of bevantolol administration to meals is not expected to influence therapeutic efficacy.

  1. Influence of circulating epinephrine on absorption of subcutaneously injected insulin

    SciTech Connect

    Fernqvist, E.; Gunnarsson, R.; Linde, B.

    1988-06-01

    Effects of epinephrine (Epi) infusion on the absorption of subcutaneously injected 125I-labeled soluble human insulin (10 U) from the thigh or the abdomen were studied in 16 healthy subjects and from the thigh in 10 insulin-dependent diabetic (IDDM) patients. Epi was infused at 0.3 (high dose) or 0.1 (low dose; healthy subjects) nmol.kg-1.min-1 i.v., resulting in arterial plasma Epi levels of approximately 6 and 2 nM, respectively. Saline was infused on a control day. Insulin absorption was measured as disappearance of radioactivity from the injection site and as appearance of plasma immunoreactive insulin (IRI). Adipose tissue blood flow was measured with the 133Xe clearance technique. First-order disappearance rate constants of 125I from the thigh depot decreased approximately 40-50% during the high dose of Epi compared with control (P less than .001). The corresponding decrease from the abdominal depot was approximately 40% (P less than .001), whereas no significant change was found during the low Epi dose. IRI fell compared with control in all groups at the high Epi dose. The Epi-induced depression of insulin absorption occurred despite unaltered or even slightly increased subcutaneous blood flow. The results indicate that circulating Epi at levels seen during moderate physical stress depresses the absorption of soluble insulin from subcutaneous injection sites to an extent that might be important for glycemic control in IDDM patients. Furthermore, dissociation is found between changes in insulin absorption and subcutaneous blood flow during Epi infusion, suggesting that factors other than blood flow may also influence the absorption of subcutaneously injected insulin.

  2. Fraunhofer effect atomic absorption spectrometry.

    PubMed

    Rust, Jennifer A; Nóbrega, Joaquim A; Calloway, Clifton P; Jones, Bradley T

    2005-02-15

    The dark lines in the solar spectrum were discovered by Wollaston and cataloged by Fraunhofer in the early days of the 19th century. Some years later, Kirchhoff explained the appearance of the dark lines: the sun was acting as a continuum light source and metals in the ground state in its atmosphere were absorbing characteristic narrow regions of the spectrum. This discovery eventually spawned atomic absorption spectrometry, which became a routine technique for chemical analysis in the mid-20th century. Laboratory-based atomic absorption spectrometers differ from the original observation of the Fraunhofer lines because they have always employed a separate light source and atomizer. This article describes a novel atomic absorption device that employs a single source, the tungsten coil, as both the generator of continuum radiation and the atomizer of the analytes. A 25-microL aliquot of sample is placed on the tungsten filament removed from a commercially available 150-W light bulb. The solution is dried and ashed by applying low currents to the coil in a three-step procedure. Full power is then applied to the coil for a brief period. During this time, the coil produces white light, which may be absorbed by any metals present in the atomization cloud produced by the sample. A high-resolution spectrometer with a charge-coupled device detector monitors the emission spectrum of the coil, which includes the dark lines from the metals. Detection limits are reported for seven elements: 5 pg of Ca (422.7 nm); 2 ng of Co (352.7 nm); 200 pg of Cr (425.4 nm); 7 pg of Sr (460.7 nm); 100 pg of Yb (398.8 nm); 500 pg of Mn (403.1 nm); and 500 pg of K (404.4 nm). Simultaneous multielement analyses are possible within a 4-nm spectral window. The relative standard deviations for the seven metals are below 8% for all metals except for Ca (10.7%), which was present in the blank at measurable levels. Analysis of a standard reference material (drinking water) resulted in a mean percent

  3. Temperature dependence of the excited state absorption of alexandrite

    SciTech Connect

    Shand, M.L.; Jenssen, H.P.

    1983-03-01

    The temperature dependence from 28 to 290/sup 0/C of the excited-state absorption cross section sigma /SUB 2a/ (E) in the gain wavelength region of alexandrite has been determined from the temperature dependence of the single pass gain (SPG) and of the fluorescence. sigma /SUB 2a/ (E) and the emission cross section increase with temperature at approximately the same rate.

  4. Absorption cross sections of the ClO dimer

    NASA Technical Reports Server (NTRS)

    Huder, K. J.; DeMore, W. B.

    1995-01-01

    The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work, new measurements were made of the dimer cross sections at 195 K. the results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%.

  5. Absorption of acetylsalicylic acid from the rat nasal cavity.

    PubMed

    Hussain, A A; Iseki, K; Kagoshima, M; Dittert, L W

    1992-04-01

    The fate of salicylate in the plasma of rats was followed after nasal, intravenous, and oral administration of 2.0-mg doses of aspirin. Aspirin was well absorbed following nasal administration of a neutralized, nonirritating solution containing triethanolamine. The rate of absorption was slower than that of other nasally administered drugs, such as propranolol or progesterone. The bioavailability of aspirin following nasal administration was 100%, whereas the oral bioavailability was only 58.8% at the dose studied. PMID:1501071

  6. Characterization of ovalbumin absorption pathways in the rat intestine, including the effects of aspirin.

    PubMed

    Yokooji, Tomoharu; Nouma, Hitomi; Matsuo, Hiroaki

    2014-01-01

    Ingested proteins are absorbed from the intestinal lumen via the paracellular and/or transcellular pathways, depending on their physicochemical properties. In this study, we investigated the absorption pathway(s) of ovalbumin (OVA), an egg white-allergen, as well as the mechanisms of aspirin-facilitated OVA absorption in rats. In situ intestinal re-circulating perfusion experiments showed that the absorption rate of fluorescein isothiocyanate (FITC)-labeled OVA in the distal intestine was higher than that for a marker of non-specific absorption, FITC-dextran (FD-40), and that colchicine, a general endocytosis inhibitor, suppressed OVA absorption. In the distal intestine, bafiromycin A1 and phenylarsine oxide inhibited the OVA absorption rate, whereas mehyl-β-cyclodextrin exerted no significant effects. Thus, OVA is preferentially absorbed from the distal intestine via the paracellular and receptor- and clathrin-mediated endocytic pathways. Furthermore, aspirin increased OVA absorption in the presence or absence of colchicine, indicating that aspirin facilitated OVA absorption by inducing intestinal barrier disruption and paracellular permeability.

  7. A new physiologically based pharmacokinetic model for the prediction of gastrointestinal drug absorption: translocation model.

    PubMed

    Ando, Hirotaka; Hisaka, Akihiro; Suzuki, Hiroshi

    2015-04-01

    This study aimed to construct a new local pharmacokinetic model of gastrointestinal absorption, the translocation model (TLM), using an anatomically relevant, minimally segmented structure to explain linear and nonlinear intestinal absorption, metabolism, and transport. The TLM was based on the concept of a single absorption site that flexibly moves, expands, and shrinks along with the length of the gastrointestinal tract after the intake of an oral dose. The structure of the small intestine is continuous, and various time- and location-dependent issues are freely incorporated in the analysis. Since the model has only one absorption site, understanding and modification of factors affecting absorption are simple. The absorption site is composed of four compartments: solid drug in the lumen, solution drug in the lumen, concentration in the enterocytes, and concentration in the lamina propria. The lamina propria includes the blood capillaries. Blood flow in the absorption site of the lamina propria appropriately accounts for the absorption. In the TLM, the permeability of the apical membrane and that of the basolateral membrane are distinct. By considering plicate, villi, and microvilli expansions of the surface area, the apparent permeability measured in Caco-2 experiments was converted to the effective permeability in vivo. The intestinal availability, bioavailability, and dose product of intestinal availability and absorption rate relationship of the model drugs were well explained using the TLM. The TLM would be a useful tool for the consideration of local pharmacokinetics in the gastrointestinal tract in various situations.

  8. HI Absorption in Merger Remnants

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Veileux, Sylvain; Baker, Andrew J.

    2012-01-01

    It has been proposed that ultraluminous infrared galaxies (ULIRGs) pass through a luminous starburst phase, followed by a dust-enshrouded AGN phase, and finally evolve into optically bright "naked" quasars once they shed their gas/dust reservoirs through powerful wind events. We present the results of our recent 21- cm HI survey of 21 merger remnants with the Green Bank Telescope. These remnants were selected from the QUEST (Quasar/ULIRG Evolution Study) sample of ULIRGs and PG quasars; our targets are all bolometrically dominated by AGN and sample all phases of the proposed ULIRG -> IR-excess quasar -> optical quasar sequence. We explore whether there is an evolutionary connection between ULIRGs and quasars by looking for the occurrence of HI absorption tracing neutral gas outflows; our results will allow us to identify where along the sequence the majority of a merger's gas reservoir is expelled.

  9. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

    Brief descriptions are given of twenty-two modular computer programs for performing the basic numerical computations of absorption spectrophotometry. The programs, written in Fortran IV for card input and output, are available from the National Research Council of Canada. The input and output formats are standardized to permit easy interfacing to yield more complex data processing systems. Though these programs were developed for ir spectrophotometry, they are readily modified for use with digitized visual and uv spectrophotometers. The operations covered include ordinate and abscissal unit and scale interconversions, ordinate addition and subtraction, location of band maxima and minima, smoothing and differentiation, slit function convolution and deconvolution, band profile analysis and asymmetry quantification, Fourier transformation to time correlation curves, multiple overlapping band separation in terms of Cauchy (Lorentz), Gauss, Cauchy-Gauss product, and Cauchy-Gauss sum functions and cell path length determination from fringe spacing analysis. PMID:20072266

  10. Quantum-enhanced absorption refrigerators

    NASA Astrophysics Data System (ADS)

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-02-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators.

  11. Multistage quantum absorption heat pumps.

    PubMed

    Correa, Luis A

    2014-04-01

    It is well known that heat pumps, while being all limited by the same basic thermodynamic laws, may find realization on systems as "small" and "quantum" as a three-level maser. In order to quantitatively assess how the performance of these devices scales with their size, we design generalized N-dimensional ideal heat pumps by merging N-2 elementary three-level stages. We set them to operate in the absorption chiller mode between given hot and cold baths and study their maximum achievable cooling power and the corresponding efficiency as a function of N. While the efficiency at maximum power is roughly size-independent, the power itself slightly increases with the dimension, quickly saturating to a constant. Thus, interestingly, scaling up autonomous quantum heat pumps does not render a significant enhancement beyond the optimal double-stage configuration.

  12. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  13. Backscatter absorption gas imaging system

    DOEpatents

    McRae, T.G. Jr.

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  14. Backscatter absorption gas imaging system

    DOEpatents

    McRae, Jr., Thomas G.

    1985-01-01

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  15. Transient simulation of absorption machines

    NASA Astrophysics Data System (ADS)

    Anand, D. K.; Allen, R. W.; Kumar, B.

    A model for a water-cooled Lithium-Bromide/water absorption chiller is presented. Its transient response both during the start-up phase and during the shut-off period is predicted. The simulation model incorporates such influencing factors as the thermodynamic properties of the working fluid, the absorbent, the heat-transfer configuration of different components of the chiller and related physical data. The time constants of different components are controlled by a set of key parameters that have been identified. The results show a variable but at times significant amount of time delay before the chiller capacity gets close to its steady-state value. The model is intended to provide an insight into the mechanism of build-up to steady-state performance. By recognizing the significant factors contributing to transient degradation, steps can be taken to reduce such degradation.

  16. Quantum-enhanced absorption refrigerators.

    PubMed

    Correa, Luis A; Palao, José P; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860

  17. Olefin recovery via chemical absorption

    SciTech Connect

    Barchas, R.

    1998-06-01

    The recovery of fight olefins in petrochemical plants has generally been accomplished through cryogenic distillation, a process which is very capital and energy intensive. In an effort to simplify the recovery process and reduce its cost, BP Chemicals has developed a chemical absorption technology based on an aqueous silver nitrate solution. Stone & Webster is now marketing, licensing, and engineering the technology. The process is commercially ready for recovering olefins from olefin derivative plant vent gases, such as vents from polyethylene, polypropylene, ethylene oxide, and synthetic ethanol units. The process can also be used to debottleneck C{sub 2} or C{sub 3} splinters, or to improve olefin product purity. This paper presents the olefin recovery imp technology, discusses its applications, and presents economics for the recovery of ethylene and propylene.

  18. Neutron scattering and absorption properties

    SciTech Connect

    Holden, N.E.

    1993-12-01

    The Table in this report presents an evaluated set of values for the experimental quantities, which characterize the properties for scattering and absorption of neutrons. The neutron cross section is given for room temperature neutrons, 20.43{degree}C, corresponds to a thermal neutron energy of 0.0253 electron volts (eV) or a neutron velocity of 2200 meters/second. The neutron resonance integral is defined over the energy range from 0.5 eV to 0.1 {times} 10{sup 6} eV, or 0.1 MeV. A list of the major references used is given below. The literature cutoff data is October 1993. Uncertainties are given in parentheses. Parentheses with two or more numbers indicate values to the excited states(s) and to the ground state of the product nucleus.

  19. Graphene intracavity spaser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Lozovik, Yu. E.; Nechepurenko, I. A.; Dorofeenko, A. V.

    2016-09-01

    We propose an intracavity plasmon absorption spectroscopy method based on graphene active plasmonics. It is shown that the plasmonic cavity contribution to the sensitivity is proportional to the quality factor Q of the graphene plasmonic cavity and reaches two orders of magnitude. The addition of gain medium into the cavity increases the sensitivity of method. Maximum sensitivity is reached in the vicinity of the plasmon generation threshold. The gain contribution to the sensitivity is proportional to Q1/2. The giant amplification of sensitivity in the graphene plasmon generator is associated with a huge path length, limited only by the decoherence processes. An analytical estimation of the sensitivity to loss caused by analyzed particles (molecules, nanoparticles, etc.) normalized by the single pass plasmon scheme is derived. Usage of graphene nanoflakes as plasmonic cavity allows a high spatial resolution to be reached, in addition to high sensitivity.

  20. Energy absorption by polymer crazing

    NASA Technical Reports Server (NTRS)

    Pang, S. S.; Zhang, Z. D.; Chern, S. S.; Hsiao, C. C.

    1983-01-01

    During the past thirty years, a tremendous amount of research was done on the development of crazing in polymers. The phenomenon of crazing was recognized as an unusual deformation behavior associated with a process of molecular orientation in a solid to resist failure. The craze absorbs a fairly large amount of energy during the crazing process. When a craze does occur the surrounding bulk material is usually stretched to several hundred percent of its original dimension and creates a new phase. The total energy absorbed by a craze during the crazing process in creep was calculated analytically with the help of some experimental measurements. A comparison of the energy absorption by the new phase and that by the original bulk uncrazed medium is made.

  1. Monitoring PVD metal vapors using laser absorption spectroscopy

    SciTech Connect

    Braun, D.G.; Anklam, T.M.; Berzins, L.V.; Hagans, K.G.

    1994-04-01

    Laser absorption spectroscopy (LAS) has been used by the Atomic Vapor Laser Isotope Separation (AVLIS) program for over 10 years to monitor the co-vaporization of uranium and iron in its separators. During that time, LAS has proven to be an accurate and reliable method to monitor both the density and composition of the vapor. It has distinct advantages over other rate monitors, in that it is completely non-obtrusive to the vaporization process and its accuracy is unaffected by the duration of the run. Additionally, the LAS diagnostic has been incorporated into a very successful process control system. LAS requires only a line of sight through the vacuum chamber, as all hardware is external to the vessel. The laser is swept in frequency through an absorption line of interest. In the process a baseline is established, and the line integrated density is determined from the absorption profile. The measurement requires no hardware calibration. Through a proper choice of the atomic transition, a wide range of elements and densities have been monitored (e.g. nickel, iron, cerium and gadolinium). A great deal of information about the vapor plume can be obtained from the measured absorption profiles. By monitoring different species at the same location, the composition of the vapor is measured in real time. By measuring the same density at different locations, the spatial profile of the vapor plume is determined. The shape of the absorption profile is used to obtain the flow speed of the vapor. Finally, all of the above information is used evaluate the total vaporization rate.

  2. H{alpha} ABSORPTION IN TRANSITING EXOPLANET ATMOSPHERES

    SciTech Connect

    Christie, Duncan; Arras, Phil; Li Zhiyun E-mail: pla7y@virginia.edu

    2013-08-01

    Absorption of stellar H{alpha} by the upper atmosphere of the planet HD 189733b has recently been detected by Jensen et al. Motivated by this observation, we have developed a model for atomic hydrogen in the n = 2 state and compared the resulting H{alpha} line profile to the observations. The model atmosphere is in hydrostatic balance, as well as thermal and photoionization equilibrium. Collisional and radiative transitions are included in the determination of the n = 2 state level population. We find that H{alpha} absorption is dominated by an optical depth {tau} {approx} 1 shell, composed of hydrogen in the metastable 2s state that is located below the hydrogen ionization layer. The number density of the 2s state within the shell is found to vary slowly with radius, while that of the 1s state falls rapidly. Thus while the Ly{alpha} absorption, for a certain wavelength, occurs inside a relatively well defined impact parameter, the contribution to H{alpha} absorption is roughly uniform over the entire atomic hydrogen layer. The model can approximately reproduce the observed Ly{alpha} and H{alpha} integrated transit depths for HD 189733b by using an ionization rate enhanced over that expected for the star by an order of magnitude. For HD 209458b, we are unable to explain the asymmetric H{alpha} line profile observed by Jensen et al., as the model produces a symmetric line profile with transit depth comparable to that of HD 189733b. In an appendix, we study the effect of the stellar Ly{alpha} absorption on the net cooling rate.

  3. Hydrogen absorption in iron exposed to simulated concrete pore solutions

    SciTech Connect

    Lillard, R.S.; Scully, J.R.

    1996-02-01

    Safe cathodic protection (CP) limits are required for prestressed steel in concrete to avoid the risk of hydrogen embrittlement (HE). This preliminary study addressed some effects of concrete pore solution chemistry and metal surface condition on hydrogen absorption in iron. To accomplish this, the Devanathan-Stachurski permeation technique was used to investigate hydrogen absorption in 99.5% iron foils exposed to NaOH, saturated Ca(OH){sub 2}, and saturated Ca(OH){sub 2} + 0.6 M NaCl, all at pH 12.5. The foils used in this investigation were tested after various surface preparations: (a) polished, (b) with a thermal oxide formed by a heat treatment designed to simulate the stress relief oxide, and (c) with corrosion films to simulate an inservice tendon that was exposed to a marine environment for some time prior to CP. Hydrogen uptake in iron was most efficient for foils covered with Portland cement-based mortar, at least 2.5 times greater than that in NaOH of the same pH and hydrogen production rate. Absorption in saturated Ca(OH){sub 2} was somewhat less than that from the mortar cover. While chloride had no direct effect on the hydrogen absorption rate, the corrosion product and the thermal oxide were found to decrease hydrogen absorption compared to polished iron. The thermal oxide acted as a complete barrier at all charging current densities investigated. The effectiveness of this thermal oxide barrier to hydrogen, however, was compromised by corrosion resulting from alternate immersion exposure to a chloride environment.

  4. Regional models for phytoplankton absorption as a function of chlorophyll a concentration

    NASA Astrophysics Data System (ADS)

    Cleveland, Joan S.

    1995-07-01

    Empirical relationships for predicting phytoplanktonic absorption at 676 and 436 nm from water column chlorophyll a concentration are presented for distinct geographic regions defined by latitude. The forms of the predictive equations are controlled by underlying biological mechanisms and lend insight into these mechanisms. These region-specific models allow prediction of phytoplanktonic absorption from more easily measured parameters such as chlorophyll a concentration or in situ fluorescence and increase accuracy in modeling optical properties or primary production rates from specific absorption coefficients. Phytoplanktonic absorption can be predicted from chlorophyll a concentrations estimated from satellite-based ocean color measurements. Temperate and tropical regions exhibited statistically indistinguishable relationships at low chlorophyll so these regions were combined and treated as one. Nonlinear relationships between phytoplanktonic absorption at both 436 and 676 nm and chlorophyll a concentration for the combined temperate/tropical region suggested that pigment packaging effects were important and variable. Higher slopes between absorption and chlorophyll a at low chlorophyll supported the concept of low pigment packaging effects (thus higher specific absorption) in oligotrophic, low chlorophyll a waters. Subpolar waters displayed a distinct pattern and were defined as a separate region. Near-linear and linear relationships between phytoplanktonic absorption at 436 and 676 nm and chlorophyll a concentration indicated that influences of pigment packaging on phytoplankton specific absorption coefficients were relatively constant and uncoupled from water column chlorophyll a concentration in the subpolar region. Optical depth correlated inversely with specific absorption at 436 nm in the subpolar region, illustrating the role of photoadaptation in determining specific absorption and predictive relationships. Differences between predictive quadratic

  5. Whey protein hydrolysates enhance water absorption in the perfused small intestine of anesthetized rats.

    PubMed

    Ito, Kentaro; Yamaguchi, Makoto; Noma, Teruyuki; Yamaji, Taketo; Itoh, Hiroyuki; Oda, Munehiro

    2016-08-01

    We evaluated the effect of whey protein hydrolysates (WPH) on the water absorption rate in the small intestine using a rat small intestine perfusion model. The rate was significantly higher with 5 g/L WPH than with 5 g/L soy protein hydrolysates or physiological saline (p < 0.05). WPH dose-dependently increased the water absorption rate in the range of 1.25-10.0 g/L. WPH showed a significantly higher rate than an amino acid mixture whose composition was equal to that of WPH (p < 0.05). The addition of 4-aminomethylbenzoic acid, an inhibitor of PepT1, significantly suppressed WPH's enhancement of water absorption (p < 0.05). The rate of water absorption was significantly correlated with that of peptides/amino acids absorption in WPH (r = 0.82, p < 0.01). These data suggest that WPH have a high water absorption-promoting effect, to which PepT1 contributes.

  6. Inhibitory effect of nuts on iron absorption.

    PubMed

    Macfarlane, B J; Bezwoda, W R; Bothwell, T H; Baynes, R D; Bothwell, J E; MacPhail, A P; Lamparelli, R D; Mayet, F

    1988-02-01

    The effects on iron absorption of nuts, an important source of dietary protein in many developing countries, were measured in 137 Indian women. When the absorption from bread and nut meals (walnuts, almonds, peanuts, and hazelnuts) was compared with that from bread meals, the overall geometric mean absorption from the nut meals (1.8%) was significantly less than from the bread meals alone (6.6%, t = 9.8, p less than 0.0005). In contrast, coconut did not reduce absorption significantly. All the nuts tested contained significant amounts of two known inhibitors of Fe absorption (phytates and polyphenols) but the amounts in coconut were significantly less than in the other nuts. Fifty milligrams ascorbic acid overcame the inhibitory effects of two nuts that were tested (Brazil nuts and peanuts). This is different from that found previously for soy protein, another potent inhibitor of Fe absorption.

  7. Investigating cloud absorption effects: Global absorption properties of black carbon, tar balls, and soil dust in clouds and aerosols

    NASA Astrophysics Data System (ADS)

    Jacobson, Mark Z.

    2012-03-01

    This study examines modeled properties of black carbon (BC), tar ball (TB), and soil dust (SD) absorption within clouds and aerosols to understand better Cloud Absorption Effects I and II, which are defined as the effects on cloud heating of absorbing inclusions in hydrometeor particles and of absorbing aerosol particles interstitially between hydrometeor particles at their actual relative humidity (RH), respectively. The globally and annually averaged modeled 550 nm aerosol mass absorption coefficient (AMAC) of externally mixed BC was 6.72 (6.3-7.3) m2/g, within the laboratory range (6.3-8.7 m2/g). The global AMAC of internally mixed (IM) BC was 16.2 (13.9-18.2) m2/g, less than the measured maximum at 100% RH (23 m2/g). The resulting AMAC amplification factor due to internal mixing was 2.41 (2-2.9), with highest values in high RH regions. The global 650 nm hydrometeor mass absorption coefficient (HMAC) due to BC inclusions was 17.7 (10.6-19) m2/g, ˜9.3% higher than that of the IM-AMAC. The 650 nm HMACs of TBs and SD were half and 1/190th, respectively, that of BC. Modeled aerosol absorption optical depths were consistent with data. In column tests, BC inclusions in low and mid clouds (CAE I) gave column-integrated BC heating rates ˜200% and 235%, respectively, those of interstitial BC at the actual cloud RH (CAE II), which itself gave heating rates ˜120% and ˜130%, respectively, those of interstitial BC at the clear-sky RH. Globally, cloud optical depth increased then decreased with increasing aerosol optical depth, consistent with boomerang curves from satellite studies. Thus, CAEs, which are largely ignored, heat clouds significantly.

  8. Absorption bands in the spectrum of Io

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Jones, T. J.; Pilcher, C. B.

    1978-01-01

    Near-infrared spectra of Io in the region from 2.8 to 4.2 microns are reported which show distinct absorption features, the most notable at 4.1 microns. Frozen volatiles or atmospheric gases cannot account for these absorptions, nor do they resemble those seen in common silicate rocks. Several candidate substances, most notably nitrate and carbonate salts, show absorption features in this spectral region; the deepest band in the spectrum may be a nitrate absorption. The satellite surface is shown to be anhydrous, as indicated by the absence of the 3-micron bound water band.

  9. Neural regulation of intestinal nutrient absorption.

    PubMed

    Mourad, Fadi H; Saadé, Nayef E

    2011-10-01

    The nervous system and the gastrointestinal (GI) tract share several common features including reciprocal interconnections and several neurotransmitters and peptides known as gut peptides, neuropeptides or hormones. The processes of digestion, secretion of digestive enzymes and then absorption are regulated by the neuro-endocrine system. Luminal glucose enhances its own absorption through a neuronal reflex that involves capsaicin sensitive primary afferent (CSPA) fibres. Absorbed glucose stimulates insulin release that activates hepatoenteric neural pathways leading to an increase in the expression of glucose transporters. Adrenergic innervation increases glucose absorption through α1 and β receptors and decreases absorption through activation of α2 receptors. The vagus nerve plays an important role in the regulation of diurnal variation in transporter expression and in anticipation to food intake. Vagal CSPAs exert tonic inhibitory effects on amino acid absorption. It also plays an important role in the mediation of the inhibitory effect of intestinal amino acids on their own absorption at the level of proximal or distal segment. However, chronic extrinsic denervation leads to a decrease in intestinal amino acid absorption. Conversely, adrenergic agonists as well as activation of CSPA fibres enhance peptides uptake through the peptide transporter PEPT1. Finally, intestinal innervation plays a minimal role in the absorption of fat digestion products. Intestinal absorption of nutrients is a basic vital mechanism that depends essentially on the function of intestinal mucosa. However, intrinsic and extrinsic neural mechanisms that rely on several redundant loops are involved in immediate and long-term control of the outcome of intestinal function.

  10. Identification of THz absorption spectra of chemicals using neural networks

    NASA Astrophysics Data System (ADS)

    Shen, Jingling; Jia, Yan; Liang, Meiyan; Chen, Sijia

    2007-09-01

    Absorption spectra in the range from 0.2 to 2.6 THz of chemicals such as illicit drugs and antibiotics obtaining from Terahertz time-domain spectroscopy technique were identified successfully by artificial neural networks. Back Propagation (BP) and Self-Organizing Feature Map (SOM) were investigated to do the identification or classification, respectively. Three-layer BP neural networks were employed to identify absorption spectra of nine illicit drugs and six antibiotics. The spectra of the chemicals were used to train a BP neural network and then the absorption spectra measured in different times were identified by the trained BP neural network. The average identification rate of 76% was achieved. SOM neural networks, another important neural network which sorts input vectors by their similarity, was used to sort 60 absorption spectra from 6 illicit drugs. The whole network was trained by setting a 20×20 and a 16×16 grid, and both of them had given satisfied clustering results. These results indicate that it is feasible to apply BP and SOM neural networks model in the field of THz spectra identification.

  11. Diagnostic potential of cosmic-neutrino absorption spectroscopy

    SciTech Connect

    Barenboim, Gabriela; Mena Requejo, Olga; Quigg, Chris; /Fermilab

    2004-12-01

    Annihilation of extremely energetic cosmic neutrinos on the relic-neutrino background can give rise to absorption lines at energies corresponding to formation of the electroweak gauge boson Z{sup 0}. The positions of the absorption dips are set by the masses of the relic neutrinos. Suitably intense sources of extremely energetic (10{sup 21} - 10{sup 25}-eV) cosmic neutrinos might therefore enable the determination of the absolute neutrino masses and the flavor composition of the mass eigenstates. Several factors--other than neutrino mass and composition--distort the absorption lines, however. We analyze the influence of the time-evolution of the relic-neutrino density and the consequences of neutrino decay. We consider the sensitivity of the lineshape to the age and character of extremely energetic neutrino sources, and to the thermal history of the Universe, reflected in the expansion rate. We take into account Fermi motion arising from the thermal distribution of the relic-neutrino gas. We also note the implications of Dirac vs. Majorana relics, and briefly consider unconventional neutrino histories. We ask what kinds of external information would enhance the potential of cosmic-neutrino absorption spectroscopy, and estimate the sensitivity required to make the technique a reality.

  12. Magnesium absorption from the digestive tract of sheep.

    PubMed

    Care, A D; Brown, R C; Farrar, A R; Pickard, D W

    1984-07-01

    Factors affecting absorption of Mg from the ovine rumen have been studied using either a pouch constructed from part of the dorsal rumen or by an isolated washed rumen technique in vivo. Net absorption of Mg against the prevailing electrochemical gradient was observed. An increase in the K/Na ratio within the rumen led to an increase in the potential difference across the rumen wall, blood positive, and to a decrease in the net efflux of Mg from the rumen. This decrease was due to an increase in Mg influx into the rumen. The addition of ammonium chloride (30 mmol/l) to the rumen contents also led to a reduction in net Mg absorption but to no significant change in potential difference. The effects of high K/Na ratio and high ammonium ion concentration within the rumen were additive in causing decreases in net effluxes of both Mg and Na. An inverse relationship was demonstrated between the Ca concentration in the rumen and the net absorption rate of Mg. It was concluded that the efflux of Mg across the rumen wall depends at least in part on a functional system for Na transport.

  13. Infrared absorption spectroscopy and chemical kinetics of free radicals

    SciTech Connect

    Curl, R.F.; Glass, G.P.

    1993-12-01

    This research is directed at the detection, monitoring, and study of chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. During the last year, infrared kinetic spectroscopy using excimer laser flash photolysis and color-center laser probing has been employed to study the high resolution spectrum of HCCN, the rate constant of the reaction between ethynyl (C{sub 2}H) radical and H{sub 2} in the temperature region between 295 and 875 K, and the recombination rate of propargyl (CH{sub 2}CCH) at room temperature.

  14. Simultaneous absorption of SO2 and NO from flue gas with KMnO4/NaOH solutions.

    PubMed

    Chu, H; Chien, T W; Li, S Y

    2001-07-25

    The wet scrubbing combined SOx/NOx removal system is an advanced air pollution control device. This study attempts to understand the absorption kinetics in the system. The absorption of diluted SO2 and simultaneous absorption of diluted SO2 and NO, as occurs in flue gases, in a stirred tank reactor with KMnO4/NaOH solutions were carried out at 50 degrees C. The liquid-side and gas-side mass transfer coefficients of the system were determined. The results indicate that the absorption of SO2 is close to completely gas-film controlled where the NaOH concentration is greater than 0.1 M or the KMnO4 concentration is greater than 0.05 M. The increasing gas flow rate has a positive effect on the absorption rate of SO2. The existence of O2 has no significant effect on the absorption rate of SO2. Adding SO2 would decrease the absorption rate of NO; however, the addition of NO has no effect on the absorption rate of SO2.

  15. On the Ammonia Absorption on Saturn

    NASA Astrophysics Data System (ADS)

    Tejfel, Victor G.; Karimov, A. M.; Lyssenko, P. G.; Kharitonova, G. A.

    2015-11-01

    The ammonia absorption bands centered at wavelengths of 645 and 787 nm in the visible spectrum of Saturn are very weak and overlapped with more strong absorption bands of methane. Therefore, the allocation of these bands is extremely difficult. In fact, the NH3 band 787 nm is completely masked by methane. The NH3 645 nm absorption band is superimposed on a relatively weak shortwave wing of CH4 band, in which the absorption maximum lies at the wavelength of 667 nm. In 2009, during the equinox on Saturn we have obtained the series of zonal spectrograms by scanning of the planet disk from the southern to the northern polar limb. Besides studies of latitudinal variation of the methane absorption bands we have done an attempt to trace the behavior of the absorption of ammonia in the band 645 nm. Simple selection of the pure NH3 profile of the band was not very reliable. Therefore, after normalizing to the ring spectrum and to the level of the continuous spectrum for entire band ranging from 630 to 680 nm in the equivalent widths were calculated for shortwave part of this band (630-652 nm), where the ammonia absorption is present, and a portion of the band CH4 652-680 nm. In any method of eliminating the weak part of the methane uptake in the short wing show an increased ammonia absorption in the northern hemisphere compared to the south. This same feature is observed also in the behavior of weak absorption bands of methane in contrast to the more powerful, such as CH4 725 and 787 nm. This is due to the conditions of absorption bands formation in the clouds at multiple scattering. Weak absorption bands of methane and ammonia are formed on the large effective optical depths and their behavior reflects the differences in the degree of uniformity of the aerosol component of the atmosphere of Saturn.

  16. Hydrolysis-dependent absorption of disaccharides in the rat small intestine (chronic experiments and mathematical modeling).

    PubMed

    Gromova, L V; Gruzdkov, A A

    1999-06-01

    In order to throw light on the mechanisms responsible for the enzyme-dependent absorption of disaccharides membrane hydrolysis of maltose and trehalose and the absorption of glucose (free and that derived from disaccharides) were studied in isolated loops (20 cm) of the rat small intestine in chronic experiments. The rates of glucose absorption were 0.26-0.81 micromol x min(-1) x cm(-1) when the loop was perfused with a 12.5 to 75.0 mmol/l free glucose solution, which is only insignificantly higher than the rates observed during perfusion with equivalent maltose solutions. The coupling coefficient (the ratio of glucose absorption rate to the rate of disaccharide hydrolysis) decreased from 0.90 to 0.60 with the increasing maltose concentrations in the infusate from 6.25 to 37.5 mmol/l, but remained unchanged (approximately 0.95) within the same range of trehalose concentrations. The permeability of the pre-epithelial barrier was equivalent to that of unstirred water layer of less than 40 microm thickness. Fluid absorption was within the range of 0.73-2.55 microl x min(-1) x cm(-1), and it showed a correlation with the rates of glucose absorption. The results agree with a model developed on the assumption that free glucose and that released from disaccharides share the same membrane transporters. It could be concluded that a close coupling of disaccharide hydrolysis with derived glucose absorption in chronic experiments is achieved mainly due to a high activity of glucose transporters, which are presumably not associated with membrane disaccharidases. The transcellular active transport is a predominant mechanism of disaccharide-derived glucose absorption under conditions close to physiological.

  17. Anomalous absorption in a-type asymmetric top molecules in cosmic objects

    NASA Astrophysics Data System (ADS)

    Chandra, Suresh

    Since the detection of the first molecule OH in cosmic objects in 1963, scientists got interested in identification of molecules in the cosmic objects. By now more than 170 molecules have been identified. In order to know about the physical conditions prevailing in the cool cosmic objects and about the chemical reactions going on there, scientists are interested in identification of as many molecules as possible. In some molecular clouds, the kinetic temperature is very low, 10 - 20 K. For such objects, anomalous absorption, i.e., the absorption against the cosmic microwave background, may play an important role for identification of molecules. The transition 111 - 110 at 4.829 GHz of H_2CO was the first one showing the anomalous absorption in the cosmic objects. The molecule H_2CS also has been identified in the cosmic objects. We have discussed about the anomalous absorption of 111 - 110 transition in a-type asymmetric top molecules. For the investigation, the required parameters are the radiative and collisional transition probabilities. We can calculate radiative transition probabilities between the rotational levels. Calculation of collisional rates is a tedious job. In absence of accurate collisional rates, we can investigated the anomalous absorption in a qualitative manner by using the scaled values for collisional rates. We find that anomalous absorption of 111 - 110 transition is possible, provided collisional rates satisfy the required condition.

  18. HI absorption towards low luminosity radio-loud AGNs of different accretion modes and WISE colours

    NASA Astrophysics Data System (ADS)

    Chandola, Yogesh; Saikia, D. J.

    2016-08-01

    HI absorption studies of active galaxies enable us to probe their circumnuclear regions and the general interstellar medium, and study the supply of gas which may trigger the nuclear activity. We investigated the detection rate of HI absorption on the nature of radio galaxies based on their emission-line spectra, nature of the host galaxies based on the WISE colours and their radio structure, which may help understand the different accretion modes. The highest detection rate of HI absorption is found in the `late-type' galaxies with WISE infrared colours W2-W3 > 2, which is typical of gas-rich systems, along with a compact radio structure. Almost all the high-excitation radio galaxies (HERGs) in our sample have W2-W3 > 2. The HI detection rate for low-excitation radio galaxies (LERGs) with W2-W3 > 2 and compact radio structure is high (~ 71 %). This is similar to compact HERGs with W2-W3 > 2 where, although the numbers are small, all three sources are detected with HI absorption. In HERGs, compact radio structure in the nuclear or circumnuclear region could give rise to absorption by gas in the dusty torus in addition to gas in the interstellar medium. However, higher specific star formation rate (sSFR) for the LERGs with W2-W3 > 2 suggests that HI absorption may be largely due to star-forming gas in their hosts.

  19. Fluid absorption solar energy receiver

    NASA Technical Reports Server (NTRS)

    Bair, Edward J.

    1993-01-01

    A conventional solar dynamic system transmits solar energy to the flowing fluid of a thermodynamic cycle through structures which contain the gas and thermal energy storage material. Such a heat transfer mechanism dictates that the structure operate at a higher temperature than the fluid. This investigation reports on a fluid absorption receiver where only a part of the solar energy is transmitted to the structure. The other part is absorbed directly by the fluid. By proportioning these two heat transfer paths the energy to the structure can preheat the fluid, while the energy absorbed directly by the fluid raises the fluid to its final working temperature. The surface temperatures need not exceed the output temperature of the fluid. This makes the output temperature of the gas the maximum temperature in the system. The gas can have local maximum temperatures higher than the output working temperature. However local high temperatures are quickly equilibrated, and since the gas does not emit radiation, local high temperatures do not result in a radiative heat loss. Thermal radiation, thermal conductivity, and heat exchange with the gas all help equilibrate the surface temperature.

  20. Transient simulation of absorption machines

    NASA Astrophysics Data System (ADS)

    Anand, D. K.; Allen, R. W.; Kumar, B.

    1982-08-01

    This paper presents a model for a water-cooled Lithium-Bromide/water absorption chiller and predicts its transient response both during the start-up phase and during the shutoff period. The simulation model incorporates such influencing factors as the thermodynamic properties of the working fluid, the absorbent, the heat-transfer configuration of different components of the chiller and related physical data. The time constants of different components are controlled by a set of key parameters that have been identified in this study. The results show a variable but at times significant amount of time delay before the chiller capacity gets close to its steady-state value. The model is intended to provide an insight into the mechanism of build-up to steady-state performance. By recognizing the significant factors contributing to transient degradation, steps can be taken to reduce such degradation. The evaluation of the residual capacity in the shut-off period will yield more realistic estimates of chiller COP for a chiller satisfying dynamic space cooling load.

  1. Absorption media for irreversibly gettering thionyl chloride

    DOEpatents

    Buffleben, George; Goods, Steven H.; Shepodd, Timothy; Wheeler, David R.; Whinnery, Jr., LeRoy

    2002-01-01

    Thionyl chloride is a hazardous and reactive chemical used as the liquid cathode in commercial primary batteries. Contrary to previous thinking, ASZM-TEDA.RTM. carbon (Calgon Corporation) reversibly absorbs thionyl chloride. Thus, several candidate materials were examined as irreversible getters for thionyl chloride. The capacity, rate and effect of temperature were also explored. A wide variety of likely materials were investigated through screening experiments focusing on the degree of heat generated by the reaction as well as the material absorption capacity and irreversibility, in order to help narrow the group of possible getter choices. More thorough, quantitative measurements were performed on promising materials. The best performing getter was a mixture of ZnO and ASZM-TEDA.RTM. carbon. In this example, the ZnO reacts with thionyl chloride to form ZnCl.sub.2 and SO.sub.2. The SO.sub.2 is then irreversibly gettered by ASZM-TEDA.RTM. carbon. This combination of ZnO and carbon has a high capacity, is irreversible and functions effectively above -20.degree. C.

  2. [The enhancing effect of Angelica dahurica extracts on absorption of baicalin--the active composition of Scutellaria].

    PubMed

    Zhu, Jing-yun; Liang, Xin-li; Wang, Guang-fa; Zhao, Guo-wei; Liao, Zheng-gen; Cao, Yun-chao; Chen, Xu-long; Yang, Ming

    2011-02-01

    To explore the mechanism of the absorption enhancement of Angelica dahurica extract (Ade), the absorption mechanism of baicalin in the Scutcllaria water extraction as well as the effect of Angelica dahurica extract on absorption of baicalin were investigated. In order to determine the main absorption site, everted intestinal sac model was used to study the effect of Angelica dahurica extract on the absorption of baicalin at duodenum, jejunum, ileum and colon. In situ single pass intestinal perfusion model was performed to study the absorption of various concentrations of baicalin and the effect of Angelica dahurica extract on the absorption of baicalin at the main absorption site. To authenticate the consequence of perfusion by getting the blood from the hepatic portal vein and determine the concentration of the baicalin in the blood. The result showed that baicalin could be absorbed at all of the four intestinal segments with increasing absorption amount per unit as follows: ileum > colon > jejunum > duodenum. The absorption ofbaicalin in the duodenum significantly increased with Angelica dahurica extract, thus, duodenum was chosen to be the studying site. Apparent permeability values (Papp) and absorption rate constant (Ka) of baicalin in the duodenum increased gradually with higher concentrations. When the concentration of baicalin rises to a certain degree, the absorption increase had a saturable process, the absorption of baicalin may be an active transportation. Baicalin may be not a substrate of P-gp as verapamil which had not significantly affected the Papp and Ka of baicalin. The absorption of baicalin in the duodenum significantly increased (P < 0.01) in the two models with Angelica dahurica extract and the concentration of baicalin in the blood from the hepatic portal vein showed that the Angelica dahurica extract can increase the absorption of baicalin.

  3. Low absorptance porcelain-on-aluminum coating

    NASA Technical Reports Server (NTRS)

    Leggett, H.

    1979-01-01

    Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

  4. A Low-Cost Quantitative Absorption Spectrophotometer

    ERIC Educational Resources Information Center

    Albert, Daniel R.; Todt, Michael A.; Davis, H. Floyd

    2012-01-01

    In an effort to make absorption spectrophotometry available to high school chemistry and physics classes, we have designed an inexpensive visible light absorption spectrophotometer. The spectrophotometer was constructed using LEGO blocks, a light emitting diode, optical elements (including a lens), a slide-mounted diffraction grating, and a…

  5. High-Absorptance Radiative Heat Sink

    NASA Technical Reports Server (NTRS)

    Cafferty, T.

    1983-01-01

    Absorptance of black-painted open-cell aluminum honeycomb improved by cutting honeycomb at angle or bias rather than straight across. This ensures honeycomb cavities escapes. At each reflection radiation attenuated by absorption. Applications include space-background simulators, space radiators, solar absorbers, and passive coolers for terrestrial use.

  6. Absorption of ozone by porous particles

    SciTech Connect

    Afanas'ev, V.P.; Dorofeev, S.B.; Sinitsyn, V.I.; Smirnov, B.M.

    1981-11-01

    The absorption of ozone by porous zeolite, silica gel, and activated carbon particles has been studied experimentally. It was shown that in addition to absorption, dissociation of ozone on the surface plays an important and sometimes decisive role. The results obtained were used to analyze the nature of ball lightning.

  7. Do Atoms Really "Emit" Absorption Lines?

    ERIC Educational Resources Information Center

    Brecher, Kenneth

    1991-01-01

    Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

  8. Terahertz absorption spectrum of triacetone triperoxide (TATP)

    NASA Astrophysics Data System (ADS)

    Wilkinson, John; Konek, Christopher T.; Moran, Jesse S.; Witko, Ewelina M.; Korter, Timothy M.

    2009-08-01

    We report here, for the first time, the terahertz absorption spectrum of triacetone triperoxide (TATP). The experimental spectra are coupled with solid-state density functional theory, and preliminary assignments are provided to gain physical insight into the experimental spectrum. The calculated absorption coefficients are in excellent agreement with experiment.

  9. On the absorption of alendronate in rats.

    PubMed

    Lin, J H; Chen, I W; deLuna, F A

    1994-12-01

    Alendronate is an antiosteolytic agent under investigation for the treatment of a number of bone disorders. Since the compound is a zwitterion with five pKa values and is completely ionized in the intestine at the physiological pH, absorption is poor; less than 1% of an oral dose is available systemically in rats. In the present studies, absorption was found to be predominantly in the upper part of the small intestine. Administration of buffered solutions of alendronate (pH 2-11) did not improve absorption. Whereas food markedly impaired the absorption of alendronate, EDTA enhanced absorption in a dose-dependent manner. Pretreatment of rats with ulcerogenic agents, mepirizole, acetylsalicylic acid, or indomethacin, resulted in a 3-7-fold increase in the oral absorption of alendronate. The absorption of phenol red, added as an indicator of intestinal tissue damage, was also increased in rats with experimental peptic ulcers. The enhanced absorption of alendronate observed in rats with experimental peptic ulcers was attributed to the alteration of the integrity of the intestinal membrane. PMID:7891304

  10. Iron absorption from intrinsically-labeled lentils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low iron (Fe) absorption from important staple foods may contribute to Fe deficiency in developing countries. To date, there are few studies examining the Fe bioavailability of pulse crops as commonly prepared and consumed by humans. The objectives of this study were to characterize the Fe absorpt...

  11. VAPID: Voigt Absorption-Profile [Interstellar] Dabbler

    NASA Astrophysics Data System (ADS)

    Howarth, Ian D.

    2015-06-01

    VAPID (Voigt Absorption Profile [Interstellar] Dabbler) models interstellar absorption lines. It predicts profiles and optimizes model parameters by least-squares fitting to observed spectra. VAPID allows cloud parameters to be optimized with respect to several different data set simultaneously; those data sets may include observations of different transitions of a given species, and may have different S/N ratios and resolutions.

  12. Inhibition of airway surface fluid absorption by cholinergic stimulation

    PubMed Central

    Joo, Nam Soo; Krouse, Mauri E.; Choi, Jae Young; Cho, Hyung-Ju; Wine, Jeffrey J.

    2016-01-01

    In upper airways airway surface liquid (ASL) depth and clearance rates are both increased by fluid secretion. Secretion is opposed by fluid absorption, mainly via the epithelial sodium channel, ENaC. In static systems, increased fluid depth activates ENaC and decreased depth inhibits it, suggesting that secretion indirectly activates ENaC to reduce ASL depth. We propose an alternate mechanism in which cholinergic input, which causes copious airway gland secretion, also inhibits ENaC-mediated absorption. The conjoint action accelerates clearance, and the increased transport of mucus out of the airways restores ASL depth while cleansing the airways. We were intrigued by early reports of cholinergic inhibition of absorption by airways in some species. To reinvestigate this phenomenon, we studied inward short-circuit currents (Isc) in tracheal mucosa from human, sheep, pig, ferret, and rabbit and in two types of cultured cells. Basal Isc was inhibited 20–70% by the ENaC inhibitor, benzamil. Long-lasting inhibition of ENaC-dependent Isc was also produced by basolateral carbachol in all preparations except rabbit and the H441 cell line. Atropine inhibition produced a slow recovery or prevented inhibition if added before carbachol. The mechanism for inhibition was not determined and is most likely multi-factorial. However, its physiological significance is expected to be increased mucus clearance rates in cholinergically stimulated airways. PMID:26846701

  13. Zinc Absorption from Fortified Milk Powder in Adolescent Girls.

    PubMed

    Méndez, Rosa O; Hambidge, Michael; Baker, Mark; Salgado, Sergio A; Ruiz, Joaquín; García, Hugo S; Calderón de la Barca, Ana M

    2015-11-01

    Zinc (Zn) is essential for development, growth, and reproduction. The Mexican government subsidizes micronutrient-fortified milk for risk groups, with positive effect on the targeted groups' plasma Zn level, inferring a good absorption is achieved although it has not being measured. The aim of this study was to determine the impact of micronutrient-fortified milk intake during 27 days on Zn absorption in adolescent girls from northwest Mexico. Therefore, Zn absorption was evaluated in 14 healthy adolescent girls (14.1 years old) with adequate plasma Zn levels, before and after 27 days of fortified Zn milk intake. Fractional Zn absorption (FZA) was calculated from urinary ratios of stable isotopic Zn tracers administered orally and intravenously on days 0 and 27, and total absorbed Zn (TZA) was calculated. At the beginning, Zn intake was 6.8 ± 0.85 mg/d (mean ± SE), and 50 % of the adolescent girls did not achieve their requirement (7.3 mg/d). Additionally, FZA was negatively correlated with Zn intake (r =-0.61, p = 0.02), while TZA (1.06 mg/d) was insufficient to cover the physiologic requirements of adolescent girls (3.02 mg/d). At the end of the intervention, all the girls reached the Zn intake recommendation and TZA, 3.09 mg/d, which was enough to meet the physiological requirement for 57 % of the adolescent girls. Therefore, the low Zn intake and the Zn status of adolescent girls were positively impacted by Zn-fortified milk intake and its good absorption rate.

  14. Absorption imaging of a single atom.

    PubMed

    Streed, Erik W; Jechow, Andreas; Norton, Benjamin G; Kielpinski, David

    2012-07-03

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  15. Single-molecule imaging by optical absorption

    NASA Astrophysics Data System (ADS)

    Celebrano, Michele; Kukura, Philipp; Renn, Alois; Sandoghdar, Vahid

    2011-02-01

    To date, optical studies of single molecules at room temperature have relied on the use of materials with high fluorescence quantum yield combined with efficient spectral rejection of background light. To extend single-molecule studies to a much larger pallet of substances that absorb but do not fluoresce, scientists have explored the photothermal effect, interferometry, direct attenuation and stimulated emission. Indeed, very recently, three groups have succeeded in achieving single-molecule sensitivity in absorption. Here, we apply modulation-free transmission measurements known from absorption spectrometers to image single molecules under ambient conditions both in the emissive and strongly quenched states. We arrive at quantitative values for the absorption cross-section of single molecules at different wavelengths and thereby set the ground for single-molecule absorption spectroscopy. Our work has important implications for research ranging from absorption and infrared spectroscopy to sensing of unlabelled proteins at the single-molecule level.

  16. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect

    Xue, Y.

    1994-07-27

    Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the {mu}M level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

  17. Creating semiconductor metafilms with designer absorption spectra.

    PubMed

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  18. Creating semiconductor metafilms with designer absorption spectra

    PubMed Central

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  19. A theoretical consideration of percutaneous drug absorption.

    PubMed

    Kubota, K; Ishizaki, T

    1985-02-01

    The percutaneous drug absorption process and its clinical significance are not fully known. In this article we propose a theoretical method to obtain two parameters (kd and kc) of percutaneous drug absorption from in vivo data. These parameters are related to diffusion of a drug through the skin and removal process at the skin-capillary boundary, respectively, characterizing several pharmacokinetic aspects of the drug applied to the skin. Moreover, by employing these two kinetic constants, a simulation of percutaneous drug absorption can be theoretically generated. On the basis of our theoretical considerations on the percutaneous drug absorption process described herein, we conclude that the percutaneous drug absorption process is better understood by employing two kinetic constants in a mathematical model and that its clinical application would be highly possible. PMID:4020622

  20. Broadband microwave absorption spectrometer for liquid media

    SciTech Connect

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

    1988-12-01

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

  1. Creating semiconductor metafilms with designer absorption spectra

    NASA Astrophysics Data System (ADS)

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-07-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells.

  2. Correlation between laser absorption and radiation conversion efficiency in laser produced tin plasma

    SciTech Connect

    Matsukuma, Hiraku Hosoda, Tatsuya; Fujioka, Shinsuke; Nishimura, Hiroaki; Sunahara, Atsushi; Yanagida, Tatsuya; Tomuro, Hiroaki; Kouge, Kouichiro; Kodama, Takeshi

    2015-09-21

    The correlation between the laser absorption and the conversion efficiency (CE) for 13.5 nm extreme ultraviolet (EUV) light in a laser-produced tin plasma was investigated. The absorption rate α and the CE were measured simultaneously for a laser-pre-formed low-density tin target as a function of the time delay between the pre-pulse and the main laser pulse. A clear and positive correlation between α and CE was found with increasing delay time; however, the CE decreases rapidly at longer delay times. This result is partly attributed to a reduction in the absorption rate, but is mainly attributed to the self-absorption of EUV light in excessively long-scale plasmas.

  3. Kinetics and modeling of carbon dioxide absorption into aqueous solutions of diethanolamine

    SciTech Connect

    Rinker, E.B.; Ashour, S.S.; Sandall, O.C.

    1996-04-01

    Absorption of acid gases such as CO{sub 2} and H{sub 2}S from natural and process gases is of great industrial importance. The kinetics of the reaction between CO{sub 2} and aqueous diethanolamine (DEA) were estimated over the temperature range of 293--343 K from absorption data obtained in a laminar-liquid jet absorber. The absorption data were obtained over a wide range of DEA concentrations and for CO{sub 2} partial pressures near atmospheric. A rigorous numerical mass-transfer model based on penetration theory in which all chemical reactions are considered to be reversible was developed and used to estimate kinetic rate coefficients from the experimental absorption data. The kinetic data were found to be consistent with the zwitterion mechanism. The scarce zwitterion rate coefficient estimates reported in the literature are in fair agreement with the results of this work.

  4. Intestinal perfusion studies in tropical sprue. 1. Amino acid and dipeptide absorption.

    PubMed Central

    Hellier, M D; Radhakrishnan, A N; Ganapathy, V; Mathan, V I; Baker, S J

    1976-01-01

    Intestinal absorption of glycine 20 mmol/1, glycyl-glycine 10 mmol/1 plus L-leucine 10 mmol/1, and glycyl-L-leucine 10 mmol/1 has been studied by intestinal perfusion in 11 patients with tropical sprue and 10 control subjects. The patients with sprue had a significant reduction in the rate of absorption of glycine from a 20 mmol/1 solution, but there were no significant differences in the absorption of the other substances. The failure to demonstrate any difference in the absorption of these substances is probably related to their low concentration relative to the maximum absorptive capacity of the intestine. In both groups of subjects the kinetic advantage of glycyl-glycine absorption as compared with glycine absorption was maintained. When the dipeptides were perfused, free amino acids appeared in the perfusate presumably by "back diffusion" from the mucosal cells. In the case of glycyl-L-leucine considerably more glycine and leucine were found in the perfusate in patients with sprue than in the control subjects. There was no correlation between peptide absorption and the concentration of total glycly-glycine hydrolase and glycyl-L-leucine hydrolase, measured as combined brush border and cytosol enzymes. The concentrations of these enzymes were similar in both groups of subjects. PMID:964683

  5. [Study on intestinal absorption of formononetin in Millettia nitita var. hirsutissima in rats].

    PubMed

    Liu, Ya-Li; Xiong, Xian-Bing; Su, Dan; Song, Yong-Gui; Zhang, Ling; Yang, Shi-Lin

    2013-10-01

    To use the single-pass intestine perfusion (SPIP) model and HPLC to determine the concentration of formononetin, the effect of quality concentrations of formononetin, different intestinal segments and P-glycoprotein inhibitor on intestinal absorption of formononetin, in order to observe the intestinal absorption mechanism of formononetin from Millettia nitita var. hirsutissima in rats. The experimental results showed that the qulaity concentration of formononetin in the perfusate had no significant effect on the absorption rate constant (K(a)) and the apparent absorption coefficient (P(app)); K(a) and P(app) of formononetin in duodenum, jejunum and ileum showed no significant difference. However, K(a) was significantly higher than that in colon (P < 0.05), with significant difference between that in intestinum tenue and colon. P-glycoprotein inhibitor verapamil showed significant difference in K(a) and P(app) in intestinal segments (P < 0.05). This indicated that the absorption mechanism of formononein in rat intestinal tracts passive diffusion, without any saturated absorption. Formononein is absorbed well in all intestines. Their absorption windows were mainly concentrated in the intestinum tenue, without specific absorption sites. Formononein may be the substrate of P-glycoprotein. PMID:24490575

  6. Capturing CO2 into the precipitate of a phase-changing solvent after absorption.

    PubMed

    Zheng, Shudong; Tao, Mengna; Liu, Qing; Ning, Liqi; He, Yi; Shi, Yao

    2014-01-01

    The major drawback of aqueous alkanolamine-based CO2 capture processes is the high energy penalty for regeneration. To overcome this weakness, we studied the absorption of CO2 with amines dissolved in nonaqueous solvents. It was observed that triethylenetetramine (TETA) dissolved in ethanol produces a solid precipitate after absorption, which can then be easily separated and regenerated. As a comparison, a TETA/water solution does not form any precipitate after absorbing CO2. The TETA/ethanol solution offers several advantages for CO2 capture in absorption rate, absorption capacity, and absorbent regenerability. Both the rate and capacity of CO2 absorption with the TETA/ethanol solution were significantly higher than with a TETA/water solution, because ethanol not only promotes the solubility of CO2 in the liquid phase but also facilitates the chemical reaction between TETA and CO2. This approach was able to capture 81.8% of the absorbed CO2 in the solid phase as TETA-carbamate. In addition, results show that the decomposition of TETA-carbamate can be completed at 90 °C. Moreover, the cycling absorption/regeneration runs of the TETA/ethanol solution display a relatively stable absorption performance.

  7. Comparison of the effect of sorbitol and glucose on calcium absorption in postmenopausal women

    SciTech Connect

    Francis, R.M.; Peacock, M.; Barkworth, S.A.; Marshall, D.H.

    1986-01-01

    It has been suggested that the oral administration of sorbitol promotes calcium absorption, while glucose has no effect. We have therefore compared the effect of oral sorbitol and glucose on the absorption of radiocalcium from low and high carrier loads in healthy postmenopausal women. In a control group of 20 women given neither sorbitol nor glucose, the mean +/- SEM fractional radiocalcium absorption rate from a low carrier load was 0.65 +/- 0.05 (fraction of dose/h). In a second group of 10 women the fractional absorption rate from the low carrier load was lower (p less than 0.05) with 10 g sorbitol (0.48 +/- 0.05) than with 10 g glucose (0.65 +/- 0.08). Fractional absorption of radiocalcium from a high carrier load measured in a third group of seven women using two isotopes (oral 45Ca, IV 47Ca) was also lower (p less than 0.001) with 10 g sorbitol (0.22 +/- 0.01, fraction/3 h) than with 10 g glucose (0.29 +/- 0.02). The results suggest that calcium absorption from a low carrier load is unaltered by glucose but that absorption of calcium from both low and high carrier loads is lower with sorbitol than with glucose.

  8. Effective photons in weakly absorptive dielectric media and the Beer-Lambert-Bouguer law

    NASA Astrophysics Data System (ADS)

    Judge, A. C.; Brownless, J. S.; Bhat, N. A. R.; Sipe, J. E.; Steel, M. J.; de Sterke, C. Martijn

    2014-04-01

    We derive effective photon modes that facilitate an intuitive and convenient picture of photon dynamics in a structured Kramers-Kronig dielectric in the limit of weak absorption. Each mode is associated with a mode field distribution that includes the effects of both material and structural dispersion, and an effective line-width that determines the temporal decay rate of the photon. These results are then applied to obtain an expression for the Beer-Lambert-Bouguer law absorption coefficient for unidirectional propagation in structured media consisting of dispersive, weakly absorptive dielectric materials.

  9. Relations among low ionosphere parameters and high frequency radio wave absorption

    NASA Technical Reports Server (NTRS)

    Cipriano, J. P.

    1973-01-01

    Charged particle conductivities measured in the very low ionosphere at White Sands Missile Range, New Mexico, and Wallops Island, Virginia, are compared with atmospheric parameters and high frequency radio wave absorption measurements. Charged particle densities are derived from the conductivity data. Between 33 and 58 km, positive conductivity correlated well with neutral atmospheric temperature, with temperature coefficients as large as 4.6%/deg K. Good correlations were also found between HF radio wave absorption and negative conductivity at altitudes as low as 53 km, indicating that the day-to-day absorption variations were principally due to variations in electron loss rate.

  10. Use of inverted intestinal sacs to assess the effect of gastrointestinal insult on carcinogen absorption.

    PubMed

    Capel, I D; Cosier, R S; Pinnock, M H; Williams, D C

    1981-01-01

    Rats were subjected to various forms of treatment in the manner likely to induce gastrointestinal insult. These and control animals were sacrificed and, using inverted sacs, the rate of absorption of either dimethylnitrosamine and benzo(a)pyrene determined. The gastrointestinal injury resulting from the differing treatments did not significantly affect the absorption of benzo(a)pyrene, whereas that of dimethylnitrosamine was significantly increased after each incubation time, most notably by alcohol pretreatment. The results demonstrate that intestinal damage increases the absorption of some carcinogens.

  11. Exceptionally large two- and three-photon absorption cross-sections by OPV organometalation.

    PubMed

    Gao, Beibei; Mazur, Leszek M; Morshedi, Mahbod; Barlow, Adam; Wang, Huan; Quintana, Cristóbal; Zhang, Chi; Samoc, Marek; Cifuentes, Marie P; Humphrey, Mark G

    2016-07-01

    Oligo(p-phenylenevinylene)s (OPVs) containing up to 8 PV units and end-functionalized by ruthenium alkynyl groups have been prepared and their nonlinear absorption properties assessed using the Z-scan technique and employing low repetition rate femtosecond pulses. Exceptionally large two-photon absorption (ca. 12 500 GM at 725 nm) and three-photon absorption cross sections (ca. 1.6 × 10(-76) cm(6) s(2) at 1100 nm) are found for the 8PV-containing example, highlighting the potential of an "organometalation" approach to NLO-efficient organic materials. PMID:27297290

  12. Effects of absorption on high-latitude meteor scatter communication systems

    SciTech Connect

    Ostergaard, J.C.; Weitzen, J.A.; Kossey, P.A.; Bailey, A.D.; Bench, P.M. USAF, Geophysics Laboratory, Hanscom AFB, MA )

    1991-08-01

    Propagation data covering the solar disturbances of March and August 1989, acquired with the Geophysical Laboratory's High-Latitude Meteor Scatter Test-Bed, are presented and are examined as a function of frequency. It was found that the two solar-disturbance events were very different. The August event was dominated by ionospheric absorption which affected meteor arrival rates and duty cycles primarily at 35 and 45 MHz, while the March event combined weak ionospheric absorption with large solar noise burst. The absorption was frequency dependent during both events. 21 refs.

  13. In silico modelling of mass transfer & absorption in the human gut

    PubMed Central

    Moxon, T.E.; Gouseti, O.; Bakalis, S.

    2016-01-01

    An in silico model has been developed to investigate the digestion and absorption of starch and glucose in the small intestine. The main question we are aiming to address is the relative effect of gastric empting time and luminal viscosity on the rate of glucose absorption. The results indicate that all factors have a significant effect on the amount of glucose absorbed. For low luminal viscosities (e.g. lower than 0.1 Pas) the rate of absorption is controlled by the gastric emptying time. For viscosities higher than 0.1 Pas a 10 fold increase in viscosity can result in a 4 fold decrease of glucose absorbed. Our model, with the simplifications used to develop it, indicate that for high viscosity luminal phases, gastric emptying rate is not the controlling mechanism for nutrient availability. Developing a mechanistic model could help elucidate the rate limiting steps that control the digestion process. PMID:27143811

  14. A four compartment open model with first-order absorption.

    PubMed

    Cherruault, Y; Sarin, V B

    1993-03-01

    This paper is related to the identification of pharmacokinetic parameters of a four-compartment open model with first order absorption from plasma level data. The eigenvalues of the characteristic matrix of the given system are obtained by transforming them into a single variable and the solution involves the minimization of the sum of squares of deviation of the model-predicted values of the state variables from an experimentally obtained values. The distribution volume and the lag time are also identified. Finally, the unicity of the absorption rate constant is obtained by the minimum energy principle. The results obtained with present method are compared with those obtained by the generalized least squares method.

  15. Oxygen detection using the laser diode absorption technique

    NASA Technical Reports Server (NTRS)

    Disimile, P. J.; Fox, C. W.

    1991-01-01

    Accurate measurement of the concentration and flow rate of gaseous oxygen is becoming of greater importance. The detection technique presented is based on the principal of light absorption by the Oxygen A-Band. Oxygen molecules have characteristics which attenuate radiation in the 759-770 nm wavelength range. With an ability to measure changes in the relative light transmission to less than 0.01 percent, a sensitive optical gas detection system was configured. This system is smaller in size and light in weight, has low energy requirements and has a rapid response time. In this research program, the application of temperature tuning laser diodes and their ability to be wavelength shifted to a selected absorption spectral peak has allowed concentrations as low as 1300 ppm to be detected.

  16. Temperature-dependent absorption cross sections for hydrogen peroxide vapor

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1988-01-01

    Relative absorption cross sections for hydrogen peroxide vapor were measured over the temperature ranges 285-381 K for lambda = 230 nm-295 nm and 300-381 K for lambda = 193 nm-350 nm. The well established 298 K cross sections at 202.6 and 228.8 nm were used as an absolute calibration. A significant temperature dependence was observed at the important tropospheric photolysis wavelengths lambda over 300 nm. Measured cross sections were extrapolated to lower temperatures, using a simple model which attributes the observed temperature dependence to enhanced absorption by molecules possessing one quantum of O-O stretch vibrational excitation. Upper tropospheric photodissociation rates calculated using the extrapolated cross sections are about 25 percent lower than those calculated using currently recommended 298 K cross sections.

  17. Constant optimization of oral drug absorption kinetics in the compartment absorption and transit models using particle swarm optimization algorithm

    NASA Astrophysics Data System (ADS)

    Prabowo, K.; Sumaryada, T.; Kartono, A.

    2016-01-01

    Simulation of predictive modeling oral drug namely Compartment Absorption and Transit (CAT) using Particle Swarm Optimization (PSO) algorithm has been performed. This research will be carried out optimization of kinetic constant value oral drug use PSO algorithm to obtain the best global transport constant values for CAT equation that can predict drug concentration in plasma. The value of drug absorption rate constant for drug atenolol 25 mg is k10, k12, k21, k13 and k31 with each value is 0.8562, 0.3736, 0.2191, 0.4334 and 1.000 have been obtained thus raising the value of the coefficient of determination of a model CAT. From the experimental data plasma drug concentrations used are Atenolol, the coefficient of determination (R2) obtained from simulations atenolol 25 mg (PSO) was 81.72% and 99.46%. Better correlation between the dependent variable as the drug concentration and explanatory variables such as mass medication, plasma volume, and rate of absorption of the drug has increased in CAT models using PSO algorithm. Based on the results of CAT models fit charts can predict drug concentration in plasma.

  18. Biopharmaceutics classification and intestinal absorption study of apigenin.

    PubMed

    Zhang, Jianjun; Liu, Dapeng; Huang, Yanting; Gao, Yuan; Qian, Shuai

    2012-10-15

    The aim of the study was to characterize the biopharmaceutics classification system (BCS) category of apigenin (AP) using intrinsic dissolution rate (IDR) and rat intestinal permeability, and to investigate the intestinal absorption mechanism of AP in rats. In the present investigation, equilibrium solubility and intrinsic dissolution rate (IDR) of AP were estimated in phosphate buffers. Effective intestinal permeability (P(eff)) of AP was determined using single-pass intestinal perfusion (SPIP) technique in four segments (duodenum, jejunum, ileum and colon) of rat intestine at three concentrations (10, 50 and 100 μg/ml). The aqueous solubility of AP in tested phosphate buffers was very poor with maximum solubility of 2.16 μg/ml at pH 7.5. The IDR of AP was very low with a value of 0.006 mg/min/cm(2). The minimum and maximum P(eff)s determined by SPIP were 0.198×10(-4) and 0.713×10(-4) cm/s at jejunum and duodenum site, respectively. In addition, the concentration-dependent permeability behavior was observed in the duodenum and jejunum, which suggested that AP was transported by both passive and active carrier-mediated saturable mechanism in these two intestinal segments. However, the observed concentration-independent permeability behavior in ileum and colon indicated primarily passive transport mechanism of absorption of AP in the last two intestinal segments. AP was classified as class II drug of the BCS due to its low solubility and high intestinal permeability. AP could be well absorbed in the whole intestine with the main absorption site at duodenum. The absorption of AP in four intestinal segments exhibited different transport mechanisms.

  19. Integrated CO2, Humidity and Thermal Control by Membrane Gas Absorption, Results of Breadboard Testing

    NASA Astrophysics Data System (ADS)

    van Driel, C.; Eckhard, F.; Feron, P. H. M.; Savage, C. J.

    2002-01-01

    Membrane gas absorption for the removal of CO2 in manned spacecrafts is subject of study by Stork and TNO for many years. The system is based on the combination of membrane separation and gas absorption. The air is fed along one side of a hydrophobic membrane and diffuses through the membrane after which the CO2 is selectively absorbed by an absorption liquid. Great advantage is that the system not only can be used to remove the carbon dioxide but also can be applied to control the relative humidity and temperature of the cabin atmosphere. Absorption of moisture and heat is achieved by cooling the absorption liquid below the dewpoint temperature of the gas stream. In the studies, the Crew Transfer Vehicle is used as a basis. Compared to the planned h/w for this vehicle, an air conditioning system, consisting of a condensing heat exchanger, LiOH cartridges to remove the carbon dioxide and a water evaporator assembly, the MGA/MGD has a large volume and a small mass advantage. The absorption liquid circulates through the spacecraft thermal control loop, replacing the coolant water. This set-up has two advantages. At first, by increasing the absorption liquid temperature the CO2 desorption rate in the desorber is favoured and secondly, should additional heat rejection aside from the basic heat rejection system be required (off nominal case), this can be established by dumping extra water via the desorption module, using the associated heat of vaporisation. Control of the water desorption rate is achieved by adjusting the permeate pressure with the throttle valve. In the nominal case the water absorption rate is equal to the desorption rate. The CO2 absorption capacity of the absorption liquid is restored in a desorption unit. This process is based on pervaporation. On one side of the membrane the absorption liquid is fed, on the other side a reduced pressure is maintained. Due to this pressure difference a driving force for water vapour and CO2 is created. The water

  20. Analysis of the absorption kinetics of macromolecules following intradermal and subcutaneous administration.

    PubMed

    Milewski, Mikolaj; Manser, Kimberly; Nissley, Becky P; Mitra, Amitava

    2015-01-01

    Recent years have witnessed rapid growth in the area of microneedle-assisted intradermal drug delivery. Several publications involving in vivo studies in humans and minipigs have demonstrated distinct change in pharmacokinetics of peptides and proteins following intradermal (ID) administration as compared to subcutaneous (SC) injections. Specifically, ID administration produced a "left-shift" in pharmacokinetic profiles i.e. shorter time to achieve maximum plasma concentrations (shorter Tmax), and often higher maximum plasma concentrations (higher Cmax), as compared to the SC route. In the present work differences in the kinetics of drug absorption after ID and SC administration were explored for eight peptides and proteins with the focus on obtaining quantitative information about the absorption process and identifying similarities and differences in the absorption behavior across compounds. We confirmed that systemic uptake, as judged by apparent absorption rate constants, was 2- to 20-fold higher from the dermis as compared to the subcutis. Additionally, shapes of time-resolved absorption rate profiles demonstrated notable differences in absorption kinetics between ID and SC routes. For both administration routes evaluated herein there was a general trend of small macromolecules absorbing at higher rates as compared to the large macromolecules.

  1. Absorption of current use pesticides by snapping turtle (Chelydra serpentina) eggs in treated soil.

    PubMed

    Solla, Shane Raymond de; Martin, Pamela Anne

    2011-10-01

    Reptiles often breed within agricultural and urban environments that receive frequent pesticide use. Consequently, their eggs and thus developing embryos may be exposed to pesticides. Our objectives were to determine (i) if turtle eggs are capable of absorbing pesticides from treated soil, and (ii) if pesticide absorption rates can be predicted by their chemical and physical properties. Snapping turtle (Chelydra serpentina) eggs were incubated in soil that was treated with 10 pesticides (atrazine, simazine, metolachlor, azinphos-methyl, dimethoate, chlorpyrifos, carbaryl, endosulfan (I and II), captan, and chlorothalonil). There were two treatments, consisting of pesticides applied at application rate equivalents of 1.92 or 19.2 kg a.i/ha. Eggs were removed after one and eight days of exposure and analyzed for pesticides using gas chromatography coupled with a mass selective detector (GC-MSD) or high performance liquid chromatography (HPLC). Absorption of pesticides in eggs from soil increased with both magnitude and duration of exposure. Of the 10 pesticides, atrazine and metolachlor generally had the greatest absorption, while azinphos-methyl had the lowest. Chlorothalonil was below detection limits at both exposure rates. Our preliminary model suggests that pesticides having the highest absorption into eggs tended to have both low sorption to organic carbon or lipids, and high water solubility. For pesticides with high water solubility, high vapor pressure may also increase absorption. As our model is preliminary, confirmatory studies are needed to elucidate pesticide absorption in turtle eggs and the potential risk they may pose to embryonic development. PMID:21862099

  2. Microwave and optical saturable absorption in graphene.

    PubMed

    Zheng, Zhiwei; Zhao, Chujun; Lu, Shunbin; Chen, Yu; Li, Ying; Zhang, Han; Wen, Shuangchun

    2012-10-01

    We report on the first experiments on saturable absorption in graphene at microwave frequency band. Almost independent of the incident frequency, microwave absorbance of graphene always decreases with increasing the power and reaches at a constant level for power larger than 80 µW, evidencing the microwave saturable absorption property of graphene. Optical saturable absorption of the same graphene sample was also experimentally confirmed by an open-aperture Z-scan technique by one laser at telecommunication band and another pico-second laser at 1053 nm, respectively. Herein, we are able to conclude that graphene is indeed a broadband saturable absorber that can operate at both microwave and optical band.

  3. The gastrointestinal absorption of the actinide elements.

    PubMed

    Harrison, J D

    1991-03-01

    The greatest uncertainty in dose estimates for the ingestion of long-lived, alpha-emitting isotopes of the actinide elements is in the values used for their fractional absorption from the gastrointestinal tract (f1 values). Recent years have seen a large increase in the available data on actinide absorption. Human data are reviewed here, together with animal data, to illustrate the effect on absorption of chemical form, incorporation into food materials, fasting and other dietary factors, and age at ingestion. The f1 values recommended by the International Commission on Radiological Protection, by an Expert Group of the Nuclear Energy Agency and by the National Radiological Protection Board are discussed.

  4. Coherent Absorption of N00N States.

    PubMed

    Roger, Thomas; Restuccia, Sara; Lyons, Ashley; Giovannini, Daniel; Romero, Jacquiline; Jeffers, John; Padgett, Miles; Faccio, Daniele

    2016-07-01

    Recent results in deeply subwavelength thickness films demonstrate coherent control and logical gate operations with both classical and single-photon light sources. However, quantum processing and devices typically involve more than one photon and nontrivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single- or two-photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features, opening up applications in multiphoton spectroscopy and imaging. PMID:27447505

  5. Coherent Absorption of N00N States

    NASA Astrophysics Data System (ADS)

    Roger, Thomas; Restuccia, Sara; Lyons, Ashley; Giovannini, Daniel; Romero, Jacquiline; Jeffers, John; Padgett, Miles; Faccio, Daniele

    2016-07-01

    Recent results in deeply subwavelength thickness films demonstrate coherent control and logical gate operations with both classical and single-photon light sources. However, quantum processing and devices typically involve more than one photon and nontrivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single- or two-photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features, opening up applications in multiphoton spectroscopy and imaging.

  6. Extraordinary Absorption of Decorated Undoped Graphene

    NASA Astrophysics Data System (ADS)

    Stauber, T.; Gómez-Santos, G.; de Abajo, F. Javier García

    2014-02-01

    We theoretically study absorption by an undoped graphene layer decorated with arrays of small particles. We discuss periodic and random arrays within a common formalism, which predicts a maximum absorption of 50% for suspended graphene in both cases. The limits of weak and strong scatterers are investigated, and an unusual dependence on particle-graphene separation is found and explained in terms of the effective number of contributing evanescent diffraction orders of the array. Our results can be important to boost absorption by single-layer graphene due to its simple setup with potential applications to light harvesting and photodetection based on energy (Förster) rather than charge transfer.

  7. Selective coherent perfect absorption in metamaterials

    SciTech Connect

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-17

    We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency.

  8. Electric modulation of optical absorption in nanowires

    NASA Astrophysics Data System (ADS)

    Sakr, M. R.

    2016-11-01

    We have calculated the effect of an external electric field on the intersubband optical absorption of a nanowire subjected to a perpendicular magnetic field and Rashba effect. The absorption peaks due to optical transitions that are forbidden in the absence of the intersubband coupling experience strong amplitude modulation. This effect is quadratic in electric fields applied along the direction of quantum confinement or perpendicularly to tune the Rashba parameter. The electric field also induces frequency modulation in the associated spectrum. On the other hand, transitions that are normally allowed show, to a large extent, a parallel band effect, and accordingly they are responsible for strong optical absorption.

  9. Total absorption by degenerate critical coupling

    SciTech Connect

    Piper, Jessica R. Liu, Victor; Fan, Shanhui

    2014-06-23

    We consider a mirror-symmetric resonator with two ports. We show that, when excited from a single port, complete absorption can be achieved through critical coupling to degenerate resonances with opposite symmetry. Moreover, any time two resonances with opposite symmetry are degenerate in frequency and absorption is always significantly enhanced. In contrast, when two resonances with the same symmetry are nearly degenerate, there is no absorption enhancement. We numerically demonstrate these effects using a graphene monolayer on top of a photonic crystal slab, illuminated from a single side in the near-infrared.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  11. Optical absorption coefficients of pure water

    NASA Astrophysics Data System (ADS)

    Lu, Zheng; Zhao, Xianzhen; Fry, Edward S.

    2002-10-01

    The integrating cavity absorption meter(ICAM), which is independent of scattering effect, is used to measure the absolute values of small optical absorption coefficients of liquid. A modified ICAM is being used to measure the absorption of water in the wavelength range 300 to 700 nm. The ultrapure water produced by a two-stages water purification system reaches Type I quality. This is equal to or better than ASTM,CAP and NCCLS water quality standards. To avoid the fact that dissolved oxygen absorbs ultraviolet light due to the photochemical effect, the water sample is delivered through a nitrogen sealed system which will prevent the sample from contacting with oxygen. A compassion of our absorption spectrum with other existing data is given.

  12. Absorption mapping for characterization of glass surfaces.

    PubMed

    Commandré, M; Roche, P; Borgogno, J P; Albrand, G

    1995-05-01

    The surface quality of bare substrates and preparation procedures take on an important role in optical coating performances. The most commonly used techniques of characterization generally give information about roughness and local defects. A photothermal deflection technique is used for mapping surface absorption of fused-silica and glass substrates. We show that absorption mapping gives specific information on surface contamination of bare substrates. We present experimental results concerning substrates prepared by different cleaning and polishing techniques. We show that highly polished surfaces lead to the lowest values of residual surface absorption. Moreover the cleaning behavior of surfaces of multicomponent glasses and their optical performance in terms of absorption are proved to be different from those of fused silica.

  13. Absorption cross section of canonical acoustic holes

    SciTech Connect

    Crispino, Luis C. B.; Oliveira, Ednilton S.; Matsas, George E. A.

    2007-11-15

    We compute numerically the absorption cross section of a canonical acoustic hole for sound waves with arbitrary frequencies. Our outputs are in full agreement with the expected low- and high-frequency limits.

  14. Absorption chillers: Part of the solution

    SciTech Connect

    Occhionero, A.J. ); Hughes, P.J. ); Reid, E.A. )

    1991-01-01

    Acid rain, ozone depletion, global warming, and implementation economics are considered as they relate to the advisability of expanding the application of absorption chillers. Introductory and background information are provided to put the discussion in the proper context. Then all four issues are discussed separately as they relate to absorption chillers. Acid rain and ozone depletion concerns, and implementation economics, are found to support the expanded use of absorption chillers. The global warming concern is found to be more of a gray area, but the areas of benefit correspond well with the conditions of greatest economic advantage. All things considered, absorption chillers are believed to be part of the environmental and economic solution. It is further believed that integrated resource planning (IRP) processes that consider electric and gas technologies on an equal footing would come to the same conclusion for many regions of the United States. 9 refs., 3 tabs.

  15. Extraordinary Optical Absorption through Plasmonic Subwavelength Slits

    NASA Astrophysics Data System (ADS)

    White, Justin; Veronis, Georgios; Yu, Zongfu; Barnard, Edward; Chandran, Anu; Fan, Shanhui; Brongersma, Mark

    2009-03-01

    We report on the ability of resonant plasmonic slits to efficiently concentrate electromagnetic energy into a nanoscale volume of absorbing material placed inside or right behind the slit. This gives rise to extraordinary optical absorption (EOA) characterized by an absorption enhancement factor that well-exceeds the enhancements seen for extraordinary optical transmission (EOT) through slits. A semi-analytic Fabry-Perot model for the resonant absorption is developed and shown to quantitatively agree with full-field simulations. We show that absorption enhancements of nearly 1000% can be realized at 633nm for slits in aluminum films filled with silicon. This effect can be utilized in a wide range of applications, including high speed photodetectors, optical lithography and recording, and biosensors.

  16. Induced Transparency and Absorption in Coupled Microresonators

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Chang, Hongrok

    2004-01-01

    We review the conditions for the occurrence of coherence phenomena in passive coupled optical microresonators. We derive the effective steady-state response and determine conditions for induced transparency and absorption in these systems.

  17. Substrate effects on absorption of coated surfaces.

    PubMed

    Roche, P; Commandré, M; Escoubas, L; Borgogno, J P; Albrand, G; Lazaridνs, B

    1996-09-01

    Photothermal deflection is used for mapping the absorption of bare and coated surfaces. The same area is mapped before and after coating and also after annealing. The great importance of the substrate with respect to the total losses of the coated component is emphasized. First the influence of surface contamination of the bare substrate on the total absorption of the coated substrate is studied for BK7 and fused-silica substrates. Then the mean value of the coated-substrate absorptance is shown to be strongly dependenton the type of substrate. Experimental results show that this effect is associated with a localization of the absorption at the near surface of the substrate and at the interfaces of the film.

  18. Iron absorption from typical Latin American diets.

    PubMed

    Acosta, A; Amar, M; Cornbluth-Szarfarc, S C; Dillman, E; Fosil, M; Biachi, R G; Grebe, G; Hertrampf, E; Kremenchuzky, S; Layrisse, M

    1984-06-01

    The availability and daily absorption of iron was determined by the extrinsic label method in typical lower middle to lower class diets consumed in regions of Argentina, Brazil, Chile, Mexico, Peru, and Venezuela. Differences in iron absorption from meals up to 7-fold, could be attributed to the varying contents of absorption enhancers, eg, in meat, and of inhibitors in tea, vegetables, and wheat or maize bread. The total iron available in the diets from four countries did not meet the physiological requirements for normal subjects but deficient subjects fulfilled their requirements absorbing from 1.0 to 2.1 mg/day. In five diets heme iron (6 to 24% of the total) provided 34 to 73% of the iron absorbed. These data suggest that such absorption and utilization studies may be used to correlate the prevalence of iron deficiency in a population with certain diets and to guide fortification programs.

  19. The size dependence of sublimation rates for interplanetary ice particles

    NASA Technical Reports Server (NTRS)

    Patashnick, H.; Rupprecht, G.

    1975-01-01

    The sublimation rates for water ice have been computed as a function of particle size for various solar distances. Because of the size dependence of the absorption and emission properties of the particles, a sublimation-rate minimum evolves whose depth and position are sensitive to the spectral-absorption properties of the particle in combination with the spectral distribution of solar radiation. As a consequence, a quasistable size of interplanetary ice particles is predicted which is independent of solar distance.

  20. Carbon dioxide postcombustion capture: a novel screening study of the carbon dioxide absorption performance of 76 amines.

    PubMed

    Puxty, Graeme; Rowland, Robert; Allport, Andrew; Yang, Qi; Bown, Mark; Burns, Robert; Maeder, Marcel; Attalla, Moetaz

    2009-08-15

    The significant and rapid reduction of greenhouse gas emissions is recognized as necessary to mitigate the potential climate effects from global warming. The postcombustion capture (PCC) and storage of carbon dioxide (CO2) produced from the use of fossil fuels for electricity generation is a key technology needed to achieve these reductions. The most mature technology for CO2 capture is reversible chemical absorption into an aqueous amine solution. In this study the results from measurements of the CO2 absorption capacity of aqueous amine solutions for 76 different amines are presented. Measurements were made using both a novel isothermal gravimetric analysis (IGA) method and a traditional absorption apparatus. Seven amines, consisting of one primary, three secondary, and three tertiary amines, were identified as exhibiting outstanding absorption capacities. Most have a number of structural features in common including steric hindrance and hydroxyl functionality 2 or 3 carbons from the nitrogen. Initial CO2 absorption rate data from the IGA measurements was also used to indicate relative absorption rates. Most of the outstanding performers in terms of capacity also showed initial absorption rates comparable to the industry standard monoethanolamine (MEA). This indicates, in terms of both absorption capacity and kinetics, that they are promising candidates for further investigation.

  1. Seasonal Solar Thermal Absorption Energy Storage Development.

    PubMed

    Daguenet-Frick, Xavier; Gantenbein, Paul; Rommel, Mathias; Fumey, Benjamin; Weber, Robert; Gooneseker, Kanishka; Williamson, Tommy

    2015-01-01

    This article describes a thermochemical seasonal storage with emphasis on the development of a reaction zone for an absorption/desorption unit. The heat and mass exchanges are modelled and the design of a suitable reaction zone is explained. A tube bundle concept is retained for the heat and mass exchangers and the units are manufactured and commissioned. Furthermore, experimental results of both absorption and desorption processes are presented and the exchanged power is compared to the results of the simulations. PMID:26842331

  2. Water absorption in mortar determined by NMR.

    PubMed

    Pel, L; Hazrati, K; Kopinga, K; Marchand, J

    1998-01-01

    Nuclear magnetic resonance (NMR) offers the possibility to determine moisture profiles in porous building materials. Moreover, the relaxation of the nuclear magnetic resonance signal can provide additional information on the water distribution in the microstructure. For mortar, it is shown that the transverse relaxation yields information on the distribution of water in the gel pores and capillary pores. Moisture profiles and relaxation were measured during water absorption. The effect of the drying treatment on the microstructure and the water absorption was investigated.

  3. Ultraviolet absorption cross sections of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Lin, C. L.; Rohatgi, N. K.; Demore, W. B.

    1978-01-01

    Absorption cross-sections of hydrogen peroxide vapor and of neutral aqueous solutions of hydrogen peroxide were measured in the wavelength range from 195 to 350 nm at 296 K. The spectrophotometric procedure is described, and the reported cross-sections are compared with values obtained by other researchers. Photodissociation coefficients of atmospheric H2O2 were calculated for direct absorption of unscattered solar radiation, and the vertical distributions of these coefficients are shown for various solar zenith angles.

  4. Fluctuation sound absorption in quark matter

    NASA Astrophysics Data System (ADS)

    Kerbikov, B. O.; Lukashov, M. S.

    2016-09-01

    We investigate the sound absorption in quark matter due to the interaction of the sound wave with the precritical fluctuations of the diquark-pair field above Tc. The soft collective mode of the pair field is derived using the time-dependent Ginzburg-Landau functional with random Langevin forces. The strong absorption near the phase transition line may be viewed as a manifestation of Mandelshtam-Leontovich slow relaxation time theory.

  5. Rapid Scan Absorption Spectroscopy with Applications for Remote Sensing

    NASA Astrophysics Data System (ADS)

    Douglass, K.; Maxwell, S. E.; Truong, G.; Van Zee, R. D.; Hodges, J. T.; Plusquellic, D.; Long, D.; Whetstone, J. R.

    2013-12-01

    Our objective is to develop accurate and reliable methods for quantifying distributed carbon sources and sinks to support both mitigation efforts and climate change research. The presentation will describe a method for rapid step-scan absorption spectroscopy in the near-infrared wavelength range for the measurement of greenhouse gases. The method utilizes a fiber coupled laser system and a free space confocal cavity to effectively scan the laser system over a bandwidth of 37.5 GHz (1.25 cm-1), with a step size of 300 MHz (0.01 cm-1) and a scan rate of 40 kHz. The laser system is scanned with microwave precision over a full absorption lineshape profile. Measurements have been demonstrated in a 45 m long multipass cell for detection of carbon dioxide near 1602.4 nm (6240.6 cm-1) and for methane near 1645.5 nm (6077.2 cm 1). Ambient level detection is demonstrated using the multipass cell with a signal-to-noise ratio of ~5:1 in a 5 ms integration time. The scan speed, resolution and bandwidth are well suited for remote sensing using integrated path and differential absorption LIDAR techniques.

  6. High Performance Drying System Using Absorption Temperature Amplifier

    NASA Astrophysics Data System (ADS)

    Nomura, Tomohiro; Nishimura, Nobuya; Yabushita, Akihiro; Kashiwagi, Takao

    It is highly essential to create a high performance drying technology from the viewpoint of energy conservation. Recently the drying process using superheated steam has received a great attention for improving the energy efficiency of the conventional air drying processes. Many other advantages of this superheated steam drying include its inert atmosphere, enhanced drying rate, improved product quality and easier control. This study presents a new concept of superheated steam drying in which the absorption temperature amplifier is effectively applied in order to recover the waste heat with high efficiency. A feature of this new drying system is that, owing to a closed circuit dryer, the consumption of heating energy decreases by approximately 50% of the conventional noncirculated one, and the superheated steam conventionally discharged so as to maintain the pressure of the dryer at an atmospheric one can be reused as heating energy for the generator of the absorption temperature amplifier. In the 1st report, thermal performances of this proposed system have been analyzed by a computer simulation developed for the solar-assisted absorption heat transformer model at the steady-state operating condition. It may be fair to conclude that this drying system satisfies the desired operating conditions, although it involves some problems to be solved further in detail in future.

  7. Magnetospheres of hot Jupiters: hydrodynamic models and ultraviolet absorption

    NASA Astrophysics Data System (ADS)

    Alexander, R. D.; Wynn, G. A.; Mohammed, H.; Nichols, J. D.; Ercolano, B.

    2016-03-01

    We present hydrodynamic simulations of stellar wind-magnetosphere interactions in hot Jupiters such as WASP-12b. For fiducial stellar wind rates, we find that a planetary magnetic field of a few G produces a large magnetospheric cavity, which is typically 6-9 planetary radii in size. A bow shock invariably forms ahead of the magnetosphere, but the pre-shock gas is only mildly supersonic (with typical Mach numbers of ≃1.6-1.8) so the shock is weak. This results in a characteristic signature in the ultraviolet (UV) light curve: a broad absorption feature that leads the optical transit by 10-20 per cent in orbital phase. The shapes of our synthetic light curves are consistent with existing observations of WASP-12b, but the required near-UV optical depth (τ ˜ 0.1) can only be achieved if the shocked gas cools rapidly. We further show that radiative cooling is inefficient, so we deem it unlikely that a magnetospheric bow shock is responsible for the observed near-UV absorption. Finally, we apply our model to two other well-studied hot Jupiters (WASP-18b and HD 209458b), and suggest that UV observations of more massive short-period planets (such as WASP-18b) will provide a straightforward test to distinguish between different models of circumplanetary absorption.

  8. Effect of diet on triolein absorption in weanling rats

    SciTech Connect

    Flores, C.A.; Brannon, P.M.; Wells, M.A.; Morrill, M.; Koldovsky, O. )

    1990-01-01

    To determine the effect of altered dietary fat intake on the rate of fat absorption in the intact animal, we fed male weanling rats either a high fat-low carbohydrate (HF-LC) (calories: 67% fat, 10% carbohydrate, 20% protein) or low fat-high carbohydrate (LF-HC) (calories: 10% fat, 67% carbohydrate, 20% protein) diet for 8 days. Absorption of ({sup 14}C)triolein was estimated by determining (1) {sup 14}CO{sub 2} expiration in breath, (2) intestinal triglyceride output using Triton WR-1339, an inhibitor of lipoprotein lipase, and (3) quantitating the disappearance of labeled triolein from the gastrointestinal tract. Changes in the activity of pancreatic lipase and amylase confirmed the adaptation to altered fat and carbohydrate intake. Animals fed the HF-LC diet exhibited approximately twofold greater triolein disappearance, oxidation, and intestinal triglyceride output compared with animals fed LF-HC. There was also a highly significant linear relationship between {sup 14}CO{sub 2} excretion and intestinal triglyceride output in both diet groups. These data show that high dietary fat content markedly enhances in vivo fat absorption in the weanling rat.

  9. Root absorption and transport behavior of technetium in soybean

    SciTech Connect

    Cataldo, D.A.; Wildung, R.E.; Garland, T.R.

    1983-01-01

    The absorption characteristics and mechanisms of pertechnetate (TcO/sub 4//sup -/) uptake by hydroponically grown soybean seedlings (Glycine max cv Williams) were determined. Absorption from 10 micromolar solutions was linear for at least 6 hours, with 30% of the absorbed TcO/sub 4//sup -/ being transferred to the shoot. Evaluation of concentration-dependent adsorption rates from solutions containing 0.02 to 10 micromolar TcO/sub 4//sup -/ shows the presence of multiphasic absorption isotherms with calculated K/sub s/ values of 0.09, 8.9, and 54 micromolar for intact seedlings. The uptake of TcO/sub 4//sup -/ was inhibited by a 4-fold concentration excess of sulfate, phosphate, selenate, molybdate, and permanganate; no reduction was noted with borate, nitrate, tungstate, perrhenate, iodate, or vanadate. Analyses of kinetics of interaction TcO/sub 4//sup -/ and inhibiting anions show permanganate to be a noncompetitive inhibitor, while sulfate, phosphate, and selenate, and molybdate exhibit characteristics of competitive inhibitors of TcO/sub 4//sup -/ transport suggesting involvement of a common transport process.

  10. The Influence of Dust on the Absorptivity of Radiant Barriers

    NASA Astrophysics Data System (ADS)

    Noboa, Homero Luis

    1993-01-01

    the attic. A linear relationship between the absorptivity and the time of dust accumulation was found that can be applied to predict future barrier effectiveness based upon the rate of dust accumulation for a given location.

  11. Absorption spectra of crystalline limestones experimentally deformed or tectonised

    NASA Astrophysics Data System (ADS)

    Cervelle, B.; ChayéD'Albissin, M.; Gouet, G.; Visocekas, R.

    1982-11-01

    Diffuse-reflectance spectra have been measured for a series of samples of Carrara marble experimentally deformed under different cylindrical stress ( P = 0, 100, 250, 500, 980 bars). The creation of point defects that results has been shown up classically by irradiation with β rays (40 krads), thus producing a typical blue coloration linked with the formation of colour centres. The diffuse-reflectance spectra, measured on powders with a microscope-spectrometer in the visible range (400-800 nm), allow the determination of the absorption spectra by means of the Kubelka-Munk function. These absorption spectra have been measured for each of the deformed samples, as well as for different fractions of a very deformed specimen subsequently heated at temperatures between 100 and 500° C for a fixed time. In the same way, tectonised crystalline limestones, of various origins, were studied without any other treatment than the irradiation with β rays. From this study the following preliminary conclusions have been drawn: (1) The absorption spectrum of an undeformed but merely irradiated specimen of crystalline limestone is practically monotonous, but in the deformed specimens a broad band of absorption appears, having a maximum at 620 nm with several shoulders, the chief of which is at 520 nm. (2) This absorption band shows the existence of colour centres, the density of which can be estimated relatively by means of the chromaticity coordinates x and y of the C.I.E. obtained from the diffuse-reflectance spectra (C.I.E. = Commission Internationale de l'Éclairage). (3) An overgrinding of calcite generates defects that have the same spectra as those produced during the experimental deformation. Consequently, in obtaining the powders of grain size 50-80 μm needed for the diffuse spectrometry, great care must be exercised. (4) For a given confining pressure, the defect density is proportional to the deformation rate. (5) One can calibrate the effect of the annealing of

  12. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  13. Water vapor absorption in the atmospheric window at 239 GHz

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  14. Hadronic absorption cross sections of B{sub c}

    SciTech Connect

    Lodhi, M. A. K.; Akram, Faisal; Irfan, Shaheen

    2011-09-15

    The cross sections of B{sub c} absorption by {pi} mesons are calculated using a hadronic Lagrangian based on the SU(5) flavor symmetry. Calculated cross sections are found to be in the ranges 2-7 mb and 0.2-2 mb for the processes B{sub c}{sup +}{pi}{yields}DB and B{sub c}{sup +}{pi}{yields}D*B*, respectively, when the monopole form factor is included. These results could be useful in calculating the production rate of B{sub c} mesons in relativistic heavy ion collisions.

  15. Effect of various absorption enhancers based on tight junctions on the intestinal absorption of forsythoside A in Shuang-Huang-Lian, application to its antivirus activity

    PubMed Central

    Zhou, Wei; Zhu, Xuan Xuan; Yin, Ai Ling; Cai, Bao Chang; Wang, Hai Dan; Di, Liuqing; Shan, Jin Jun

    2014-01-01

    Background: Forsythoside A (FTA), one of the main active ingredients in Shuang–Huang–Lian (SHL), possesses strong antibacterial, antioxidant and antiviral effects, and its pharmacological effects was higher than that of other ingredients, but the absolute bioavailability orally was approximately 0.72%, which was significantly low, influencing clinical efficacies of its oral preparations seriously. Materials and Methods: In vitro Caco-2 cell and in vivo pharmacokinetics study were simultaneously performed to investigate the effects of absorption enhancers based on tight junctions: sodium caprate and water-soluble chitosan on the intestinal absorption of FTA, and the eventual mucosal epithelial damage resulted from absorption enhancers was evaluated by MTT test and morphology observation, respectively. The pharmacological effects such as antivirus activity improvement by absorption enhancers were verified by MDCK damage inhibition rate after influenza virus propagation. Results: The observations from in vitro Caco-2 cell showed that the absorption of FTA in SHL could be improved by absorption enhancers. Meanwhile, the absorption enhancing effect of water-soluble chitosan may be almost saturable up to 0.0032% (w/v), and sodium caprate at concentrations up to 0.64 mg/mL was safe, but water-soluble chitosan at different concentrations was all safe for these cells. In pharmacokinetics study, water-soluble chitosan at dosage of 50 mg/kg improved the bioavailability of FTA in SHL to the greatest extent, and was safe for gastrointestine from morphological observation. Besides, treatment with SHL with water-soluble chitosan at dosage of 50 mg/kg prevented MDCK damage after influenza virus propagation better significantly than that of control. Conclusion: Water-soluble chitosan at dosage of 50 mg/kg might be safe and effective absorption enhancer for improving the bioavailability of FTA and the antivirus activity in vitro in SHL. PMID:24695554

  16. [Study on intestinal absorption features of oligosaccharides in Morinda officinalis How. with sigle-pass perfusion].

    PubMed

    Deng, Shao-Dong; Zhang, Peng; Lin, Li; Xiao, Feng-Xia; Lin, Jing-Ran

    2015-01-01

    To study the in situ intestinal absorption of five oligosaccharides contained in Morinda officinalis How. (sucrose, kestose, nystose, 1F-Fructofuranosyinystose and Bajijiasu). The absorption of the five oligosaccharides in small intestine (duodenum, jejunum and ileum) and colon of rats and their contents were investigated by using in situ single-pass perfusion model and HPLC-ELSD. The effects of drug concentration, pH in perfusate and P-glycoprotein inhibitor on the intestinal absorption were investigated to define the intestinal absorption mechanism of the five oligosaccharides in rats. According to the results, all of the five oligosaccharides were absorbed in the whole intestine, and their absorption rates were affected by the pH of the perfusion solution, drug concentration and intestinal segments. Verapamil Hydrochloride could significantly increase the absorptive amount of sucrose and Bajijiasu, suggesting sucrose and Bajijiasu are P-gp's substrate. The five oligosaccharides are absorbed mainly through passive diffusion in the intestinal segments, without saturated absorption. They are absorbed well in all intestines and mainly in duodenum and jejunum.

  17. Characterization and intercomparison of aerosol absorption photometers: result of two intercomparison workshops

    NASA Astrophysics Data System (ADS)

    Müller, T.; Henzing, J. S.; de Leeuw, G.; Wiedensohler, A.; Alastuey, A.; Angelov, H.; Bizjak, M.; Collaud Coen, M.; Engström, J. E.; Gruening, C.; Hillamo, R.; Hoffer, A.; Imre, K.; Ivanow, P.; Jennings, G.; Sun, J. Y.; Kalivitis, N.; Karlsson, H.; Komppula, M.; Laj, P.; Li, S.-M.; Lunder, C.; Marinoni, A.; Martins Dos Santos, S.; Moerman, M.; Nowak, A.; Ogren, J. A.; Petzold, A.; Pichon, J. M.; Rodriquez, S.; Sharma, S.; Sheridan, P. J.; Teinilä, K.; Tuch, T.; Viana, M.; Virkkula, A.; Weingartner, E.; Wilhelm, R.; Wang, Y. Q.

    2010-04-01

    Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate.

  18. Characterization and intercomparison of aerosol absorption photometers: result of two intercomparison workshops

    NASA Astrophysics Data System (ADS)

    Müller, T.; Henzing, J. S.; de Leeuw, G.; Wiedensohler, A.; Alastuey, A.; Angelov, H.; Bizjak, M.; Collaud Coen, M.; Engström, J. E.; Gruening, C.; Hillamo, R.; Hoffer, A.; Imre, K.; Ivanow, P.; Jennings, G.; Sun, J. Y.; Kalivitis, N.; Karlsson, H.; Komppula, M.; Laj, P.; Li, S.-M.; Lunder, C.; Marinoni, A.; Martins Dos Santos, S.; Moerman, M.; Nowak, A.; Ogren, J. A.; Petzold, A.; Pichon, J. M.; Rodriquez, S.; Sharma, S.; Sheridan, P. J.; Teinilä, K.; Tuch, T.; Viana, M.; Virkkula, A.; Weingartner, E.; Wilhelm, R.; Wang, Y. Q.

    2011-02-01

    Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate.

  19. Paracellular Absorption Is Relatively Low in the Herbivorous Egyptian Spiny-Tailed Lizard, Uromastyx aegyptia

    PubMed Central

    McWhorter, Todd J.; Pinshow, Berry; Karasov, William H.; Tracy, Christopher R.

    2013-01-01

    Absorption of small water-soluble nutrients in vertebrate intestines occurs both by specific, mediated transport and by non-specific, passive, paracellular transport. Although it is apparent that paracellular absorption represents a significant route for nutrient absorption in many birds and mammals, especially small, flying species, its importance in ectothermic vertebrates has not previously been explored. Therefore, we measured fractional absorption (ƒ) and absorption rate of three paracellular probes (arabinose, l-rhamnose, cellobiose) and of 3-O-methyl d-glucose (absorbed by both mediated and paracellular pathways) by the large herbivorous lizard, Uromastyx aegyptia, to explore the relative importance of paracellular and mediated transport in an ectothermic, terrestrial vertebrate. Fractional absorption of 3-O-methyl d-glucose was high (ƒ = 0.73±0.04) and similar to other vertebrates; ƒ of the paracellular probes was relatively low (arabinose ƒ = 0.31±0.03, l-rhamnose ƒ = 0.19±0.02, and cellobiose ƒ = 0.14±0.02), and decreased with molecular mass, a pattern consistent with other vertebrates. Paracellular absorption accounted for approximately 24% of total 3-O-methyl d-glucose uptake, indicating low reliance on this pathway for these herbivorous lizards, a pattern similar to that found in other terrestrial vertebrates, and different from small flying endotherms (both birds and bats). PMID:23596529

  20. Light Absorption in Arctic Sea Ice - Black Carbon vs Chlorophyll

    NASA Astrophysics Data System (ADS)

    Ogunro, O. O.; Wingenter, O. W.; Elliott, S.; Hunke, E. C.; Flanner, M.; Wang, H.; Dubey, M. K.; Jeffery, N.

    2015-12-01

    The fingerprint of climate change is more obvious in the Arctic than any other place on Earth. This is not only because the surface temperature there has increased at twice the rate of global mean temperature but also because Arctic sea ice extent has reached a record low of 49% reduction relative to the 1979-2000 climatology. Radiation absorption through black carbon (BC) deposited on Arctic snow and sea ice surface is one of the major hypothesized contributors to the decline. However, we note that chlorophyll-a absorption owing to increasing biology activity in this region could be a major competitor during boreal spring. Modeling of sea-ice physical and biological processes together with experiments and field observations promise rapid progress in the quality of Arctic ice predictions. Here we develop a dynamic ice system module to investigate discrete absorption of both BC and chlorophyll in the Arctic, using BC deposition fields from version 5 of Community Atmosphere Model (CAM5) and vertically distributed layers of chlorophyll concentrations from Sea Ice Model (CICE). To this point, our black carbon mixing ratios compare well with available in situ data. Both results are in the same order of magnitude. Estimates from our calculations show that sea ice and snow around the Canadian Arctic Archipelago and Baffin Bay has the least black carbon absorption while values at the ice-ocean perimeter in the region of the Barents Sea peak significantly. With regard to pigment concentrations, high amounts of chlorophyll are produced in Arctic sea ice by the bottom microbial community, and also within the columnar pack wherever substantial biological activity takes place in the presence of moderate light. We show that the percentage of photons absorbed by chlorophyll in the spring is comparable to the amount attributed to BC, especially in areas where the total deposition rates are decreasing with time on interannual timescale. We expect a continuous increase in

  1. Further advancement of differential optical absorption spectroscopy: theory of orthogonal optical absorption spectroscopy.

    PubMed

    Liudchik, Alexander M

    2014-08-10

    A modified version of the differential optical absorption spectroscopy (DOAS) method is presented. The technique is called orthogonal optical absorption spectroscopy (OOAS). A widespread variant of DOAS with smoothing of the registered spectrum and absorption cross sections being made employing a polynomial regression is a particular case of OOAS. The concept of OOAS provides a variety of new possibilities for constructing computational schemes and analyzing the influence of different error sources on calculated concentrations. PMID:25320931

  2. [Evaluation on intestinal absorption of alkaloids extracted by different methods from Rhizoma Coptidis-Rheum rhabarum herbal pair via everted gut sacs].

    PubMed

    Chen, Kai; Wang, Yue-liang; Chen, Yan; Li, Hui; Liu, Yu-ling; Wang, Jia-qi; Zhang, Xiao-li; Liu, Wen-cong

    2015-12-01

    The research aimed to evaluate the intestinal absorption of alkaloids extracted by decoction and alcohol extraction proces- ses from Rhizoma Coptidis-Rheum rhabarum herbal pair via everted gut sacs. Berberine, palmatine, coptisine and epiberberine were the main alkaloids in this herbal pair and taken as the standard indexes in the quantitative analysis with multi-components by single marker (QAMS) method, in order to calculate absorption rate constant (Ka) and evaluate intestinal absorption characteristics of these four alkaloids extracted by different extraction methods in different intestinal segments in rats. The results showed that the four alkaloids extracted by two different processes in high, medium and low doses had linear absorption properties in the small intestine segment, which conformed to zero-order absorption rate, intestinal segment than 0.99. The absorption rate constant (Ka) of decoction group was higher than that of alcohol extraction group.

  3. [Evaluation on intestinal absorption of alkaloids extracted by different methods from Rhizoma Coptidis-Rheum rhabarum herbal pair via everted gut sacs].

    PubMed

    Chen, Kai; Wang, Yue-liang; Chen, Yan; Li, Hui; Liu, Yu-ling; Wang, Jia-qi; Zhang, Xiao-li; Liu, Wen-cong

    2015-12-01

    The research aimed to evaluate the intestinal absorption of alkaloids extracted by decoction and alcohol extraction proces- ses from Rhizoma Coptidis-Rheum rhabarum herbal pair via everted gut sacs. Berberine, palmatine, coptisine and epiberberine were the main alkaloids in this herbal pair and taken as the standard indexes in the quantitative analysis with multi-components by single marker (QAMS) method, in order to calculate absorption rate constant (Ka) and evaluate intestinal absorption characteristics of these four alkaloids extracted by different extraction methods in different intestinal segments in rats. The results showed that the four alkaloids extracted by two different processes in high, medium and low doses had linear absorption properties in the small intestine segment, which conformed to zero-order absorption rate, intestinal segment than 0.99. The absorption rate constant (Ka) of decoction group was higher than that of alcohol extraction group. PMID:27245034

  4. Radiation absorption and optimization of solar photocatalytic reactors for environmental applications.

    PubMed

    Colina-Márquez, Jose; Machuca-Martínez, Fiderman; Li Puma, Gianluca

    2010-07-01

    This study provides a systematic and quantitative approach to the analysis and optimization of solar photocatalytic reactors utilized in environmental applications such as pollutant remediation and conversion of biomass (waste) to hydrogen. Ray tracing technique was coupled with the six-flux absorption scattering model (SFM) to analyze the complex radiation field in solar compound parabolic collectors (CPC) and tubular photoreactors. The absorption of solar radiation represented by the spatial distribution of the local volumetric rate of photon absorption (LVRPA) depends strongly on catalyst loading and geometry. The total radiation absorbed in the reactors, the volumetric rate of absorption (VRPA), was analyzed as a function of the optical properties (scattering albedo) of the photocatalyst. The VRPA reached maxima at specific catalyst concentrations in close agreement with literature experimental studies. The CPC has on average 70% higher photon absorption efficiency than a tubular reactor and requires 39% less catalyst to operate under optimum conditions. The "apparent optical thickness" is proposed as a new dimensionless parameter for optimization of CPC and tubular reactors. It removes the dependence of the optimum catalyst concentration on tube diameter and photocatalyst scattering albedo. For titanium dioxide (TiO(2)) Degussa P25, maximum photon absorption occurs at apparent optical thicknesses of 7.78 for CPC and 12.97 for tubular reactors.

  5. Water-related absorption in fibrous diamonds

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    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

  6. Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

    NASA Astrophysics Data System (ADS)

    Xu, Shuwu; Huang, Yunxia; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong

    2015-07-01

    We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye.

  7. CD163 promotes hematoma absorption and improves neurological functions in patients with intracerebral hemorrhage

    PubMed Central

    Xie, Wen-jing; Yu, Hong-quan; Zhang, Yu; Liu, Qun; Meng, Hong-mei

    2016-01-01

    Clinical outcomes are positively associated with hematoma absorption. The monocyte-macrophage scavenger receptor, CD163, plays an important role in the metabolism of hemoglobin, and a soluble form of CD163 is present in plasma and other tissue fluids; therefore, we speculated that serum CD163 affects hematoma absorption after intracerebral hemorrhage. Patients with intracerebral hemorrhage were divided into high- and low-level groups according to the average CD163 level (1,977.79 ± 832.91 ng/mL). Compared with the high-level group, the low-level group had a significantly slower hematoma absorption rate, and significantly increased National Institutes of Health Stroke Scale scores and modified Rankin Scale scores. These results suggest that CD163 promotes hematoma absorption and the recovery of neurological function in patients with intracerebral hemorrhage.

  8. CD163 promotes hematoma absorption and improves neurological functions in patients with intracerebral hemorrhage.

    PubMed

    Xie, Wen-Jing; Yu, Hong-Quan; Zhang, Yu; Liu, Qun; Meng, Hong-Mei

    2016-07-01

    Clinical outcomes are positively associated with hematoma absorption. The monocyte-macrophage scavenger receptor, CD163, plays an important role in the metabolism of hemoglobin, and a soluble form of CD163 is present in plasma and other tissue fluids; therefore, we speculated that serum CD163 affects hematoma absorption after intracerebral hemorrhage. Patients with intracerebral hemorrhage were divided into high- and low-level groups according to the average CD163 level (1,977.79 ± 832.91 ng/mL). Compared with the high-level group, the low-level group had a significantly slower hematoma absorption rate, and significantly increased National Institutes of Health Stroke Scale scores and modified Rankin Scale scores. These results suggest that CD163 promotes hematoma absorption and the recovery of neurological function in patients with intracerebral hemorrhage. PMID:27630696

  9. CD163 promotes hematoma absorption and improves neurological functions in patients with intracerebral hemorrhage

    PubMed Central

    Xie, Wen-jing; Yu, Hong-quan; Zhang, Yu; Liu, Qun; Meng, Hong-mei

    2016-01-01

    Clinical outcomes are positively associated with hematoma absorption. The monocyte-macrophage scavenger receptor, CD163, plays an important role in the metabolism of hemoglobin, and a soluble form of CD163 is present in plasma and other tissue fluids; therefore, we speculated that serum CD163 affects hematoma absorption after intracerebral hemorrhage. Patients with intracerebral hemorrhage were divided into high- and low-level groups according to the average CD163 level (1,977.79 ± 832.91 ng/mL). Compared with the high-level group, the low-level group had a significantly slower hematoma absorption rate, and significantly increased National Institutes of Health Stroke Scale scores and modified Rankin Scale scores. These results suggest that CD163 promotes hematoma absorption and the recovery of neurological function in patients with intracerebral hemorrhage. PMID:27630696

  10. Avian species differences in the intestinal absorption of xenobiotics (PCB, dieldrin, Hg2+)

    USGS Publications Warehouse

    Serafin, J.A.

    1984-01-01

    Intestinal absorption of a polychlorinated biphenyl, dieldrin, and mercury (from HgCl2) was measured in adult Northern bobwhites, Eastern screech owls, American kestrels, black-crowned night-herons and mallards in vivo by an in situ luminal perfusion technique. bobwhites, screech owls and kestrels absorbed much more of each xenobiotic than black-crowned night-herons and mallards. Mallards absorbed less dieldrin and mercury than black-crowned night-herons. Mercury absorption by kestrels was more than twice that in screech owls and eight times that observed in mallards. Pronounced differences in xenobiotic absorption rates between bobwhites, screech owls and kestrels on the one hand, and black-crowned night-herons and mallards on the other, raise the possibility that absorptive ability may be associated with the phylogenetic classification of birds.

  11. Intestinal absorption of 5 chromium compounds in young black ducks (Anas rubripes)

    USGS Publications Warehouse

    Eastin, W.C.; Haseltine, S.D.; Murray, H.C.

    1980-01-01

    An in vivo intestinal perfusion technique was used to measure the absorption rates of five Cr compounds in black ducks. Cr was absorbed from saline solutions of KCr(SO4 )2 and CrO3 at a rate about 1.5 to 2.0 times greater than from solutions of Cr, Cr(NO3 )3, and Cr(C5H7O2)3. These results suggest the ionic form of Cr in solution may be an important factor in determining absorption of Cr compounds from the small intestine.

  12. Absorption of ultraviolet radiation by antarctic phytoplankton

    SciTech Connect

    Vernet, M.; Mitchell, B.G. )

    1990-01-09

    Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

  13. The ALFALFA HI Absorption Pilot Project

    NASA Astrophysics Data System (ADS)

    Macdonald, Erin; Darling, J.; ALFALFA Team

    2009-01-01

    We present the results of a pilot project to search for HI 21 cm absorption in the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) Survey. This project is the first to conduct a "blind" wide-area search for HI absorption in the local universe. The search covered 517.0 deg2 spanning 10.9h < α < 14.95h and +7.7o < δ < +16.3o. The ALFALFA survey covers -650 km s-1 < cz < 17,500 km s-1, for a Δz = 0.054 along each line of sight (11% of the cz span is lost to radio frequency interference and Galactic HI emission). There are 243 sources toward which all damped Lyα systems (N(HI) > 2x1020 cm-2) could be detected, and 3282 sources toward which N(HI) > 2x1021 cm-2 columns could be detected (assuming 100 K spin temperature, 30 km s-1 line width, and unity filling factor). We performed Green Bank Telescope follow-up observations of 13 possible absorption lines and the 250 strong sources (> 220 mJy) in our survey region. One previously known intrinsic HI absorption line in UGC 6081 was re-detected, but no additional lines were identified in the survey region. Nevertheless, this pilot project demonstrates the value and feasibility of large-area absorption line searches commensal with emission line surveys. An absorption line search of the entire 7000 deg2 ALFALFA Survey is a worthwhile undertaking, not only to identify HI absorption systems in the local universe, but to measure the fraction of HI gas not accounted for by emission line surveys. ALFALFA is a legacy survey at the Arecibo Observatory supported by NAIC and NSF.

  14. A joint model for the emission and absorption properties of damped Lyα absorption systems

    NASA Astrophysics Data System (ADS)

    Barnes, Luke A.; Haehnelt, Martin G.

    2009-07-01

    The recently discovered population of ultra-faint extended line emitters, with fluxes of a few times 10-18ergs-1cm-2 at z ~ 3, can account for the majority of the incidence rate of damped Lyα systems (DLAs) at this redshift if the line emission is interpreted as Lyα. We show here that a model similar to that proposed by Haehnelt, Steinmetz & Rauch (2000), which reproduces the incidence rate and kinematics of DLAs in the context of Λ cold dark matter models for structure formation, also reproduces the size distribution of the new population of faint Lyα emitters for plausible parameters. This lends further support to the interpretation of the emission as Lyα, as well as the identification of the emitters with the hitherto elusive population of DLA host galaxies. The observed incidence rate of DLAs together with the observed space density and size distribution of the emitters suggest a duty cycle of ~0.2-0.4 for the Lyα emission from DLA host galaxies. We further show that Lyα cooling is expected to contribute little to the Lyα emission for the majority of emitters. This leaves centrally concentrated star formation at a rate of a few tenths Msolaryr-1, surrounded by extended Lyα haloes with radii up to 30-50 kpc, as the most plausible explanation for the origin of the emission. Both the luminosity function of Lyα emission and the velocity width distribution of low ionization absorption require that galaxies inside dark matter (DM) haloes with virial velocities <~50-70kms-1 contribute little to the incidence rate of DLAs at z ~ 3, suggesting that energy and momentum input due to star formation efficiently removes gas from these haloes. Galaxies with DM haloes with virial velocities of 100-150kms-1 appear to account for the majority of DLA host galaxies. DLA host galaxies at z ~ 3 should thus become the building blocks of typical present-day galaxies like our Milky Way.

  15. UV laser long-path absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  16. X-ray absorption spectroscopy of metalloproteins.

    PubMed

    Ward, Jesse; Ollmann, Emily; Maxey, Evan; Finney, Lydia A

    2014-01-01

    Metalloproteins are enormously important in biology. While a variety of techniques exist for studying metals in biology, X-ray absorption spectroscopy is particularly useful in that it can determine the local electronic and physical structure around the metal center, and is one of the few avenues for studying "spectroscopically silent" metal ions like Zn(II) and Cu(I) that have completely filled valence bands. While X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) are useful for studying metalloprotein structure, they suffer the limitation that the detected signal is an average of all the various metal centers in the sample, which limits its usefulness for studying metal centers in situ or in cell lysates. It would be desirable to be able to separate the various proteins in a mixture prior to performing X-ray absorption studies, so that the derived signal is from one species only. Here we describe a method for performing X-ray absorption spectroscopy on protein bands following electrophoretic separation and western blotting.

  17. Absorption mode FTICR mass spectrometry imaging.

    PubMed

    Smith, Donald F; Kilgour, David P A; Konijnenburg, Marco; O'Connor, Peter B; Heeren, Ron M A

    2013-12-01

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here, we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image, and then, these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode "Datacubes" for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.

  18. Monitoring Emergent Absorption Troughs in Quasars

    NASA Astrophysics Data System (ADS)

    Hall, Patrick; Rodriguez Hidalgo, Paola; Brandt, W. Niel; Rogerson, Jesse; Filiz Ak, Nur; Chajet, Laura

    2014-02-01

    Outflows from luminous AGN are important ingredients in galaxy formation. These outflows manifest as broad absorption line (BAL) troughs in quasar spectra. Trough variability can be used to constrain the physical parameters of these absorbing structures through comparison to models and simulations of accretion disk winds. Monitoring appearing/disappearing BAL troughs can constrain the distribution of BAL trough lifetimes along our line of sight. By comparing spectra from the SDSS Data Release (DR) 7 and DR 9, we identified 68 quasars in whose spectra new absorption troughs have appeared over 300-1200 restframe days, including one trough outflowing at v=60,000 km/s. We propose to complete our third-epoch GMOS spectroscopy of the brightest of those quasars (48 in 2013AB and 9 proposed here) to measure the absorption strength in newly appeared troughs <=365 restframe days after their previous measurement. Preliminary 2013AB results indicate that troughs are not on average still strengthening between SDSS and Gemini epochs; we therefore propose observations of 40 targets to probe shorter rest-frame time separations. We also target 8 objects showing simultaneous absorption variations in multiple ionization states, to help develop methods to distinguish absorption variations from cloud motion vs. those from ionization changes within clouds.

  19. Dependence of Cr-EDTA absorption from the rumen on luminal osmotic pressure.

    PubMed

    Dobson, A; Sellers, A F; Gatewood, V H

    1976-11-01

    A method for the measurement of [51Cr]EDTA absorption from the ventral sac of the rumen with an error of the order of +/-10% is described. When a solution present in the rumen was hypotonic or isotonic, the absorption rate of [51Cr]EDTA expressed as a clearance was about 0.2 ml/min. This gave rise to negligible errors when [51Cr]EDTA was used as an unabsorbed marker to calculate net water movements. When the osmotic pressure in the rumen exceeded that of plasma by 30-40 mos-mol/kg, the absorption rate of [51Cr]EDTA appeared to be related to the degree of hypertonicity. Absorption rates as high as 8 ml/min were observed within a range of osmotic pressures normally encountered postprandially in the rumen. Under hypertonic conditions, a correction for the absorption of this large anion was necessary if passage of water into the lumen were not to be systematically overestimated.

  20. PREDICTING DRUG DISPOSITION, ABSORPTION / ELIMINATION / TRANSPORTER INTERPLAY AND THE ROLE OF FOOD ON DRUG ABSORPTION

    PubMed Central

    Custodio, Joseph M.; Wu, Chi-Yuan; Benet, Leslie Z.

    2008-01-01

    The ability to predict drug disposition involves concurrent consideration of many chemical and physiological variables and the effect of food on the rate and extent of availability adds further complexity due to postprandial changes in the gastrointestinal (GI) tract. A system that allows for the assessment of the multivariate interplay occurring following administration of an oral dose, in the presence or absence of meal, would greatly benefit the early stages of drug development. This is particularly true in an era when the majority of new molecular entities are highly permeable, poorly soluble, extensively metabolized compounds (BDDCS Class 2), which present the most complicated relationship in defining the impact of transporters due to the marked effects of transporter-enzyme interplay. This review evaluates the GI luminal environment by taking into account the absorption / transport / elimination interplay and evaluates the physiochemical property issues by taking into account the importance of solubility, permeability and metabolism. We concentrate on the BDDCS and its utility in predicting drug disposition. Furthermore, we focus on the effect of food on the extent of drug availability (F), which appears to follow closely what might be expected if a significant effect of high fat meals is inhibition of transporters. That is, high fat meals and lipidic excipients would be expected to have little effect on F for Class 1 drugs; they would increase F of Class 2 drugs, while decreasing F for Class 3 drugs. PMID:18199522

  1. Deriving in situ phytoplankton absorption for bio-optical productivity models in turbid waters

    NASA Astrophysics Data System (ADS)

    Oliver, Matthew J.; Schofield, Oscar; Bergmann, Trisha; Glenn, Scott; Orrico, Cristina; Moline, Mark

    2004-07-01

    As part of Hyperspectral Coupled Ocean Dynamics Experiment, a high-resolution hydrographic and bio-optical data set was collected from two cabled profilers at the Long-Term Ecosystem Observatory (LEO). Upwelling- and downwelling-favorable winds and a buoyant plume from the Hudson River induced large changes in hydrographic and optical structure of the water column. An absorption inversion model estimated the relative abundance of phytoplankton, colored dissolved organic matter (CDOM) and detritus, as well as the spectral exponential slopes of CDOM and detritus from in situ WET Labs nine-wavelength absorption/attenuation meter (ac-9) absorption data. Derived optical weights were proportional to the parameter concentrations and allowed for their absorptions to be calculated. Spectrally weighted phytoplankton absorption was estimated using modeled spectral irradiances and the phytoplankton absorption spectra inverted from an ac-9. Derived mean spectral absorption of phytoplankton was used in a bio-optical model estimating photosynthetic rates. Measured radiocarbon uptake productivity rates extrapolated with water mass analysis and the bio-optical modeled results agreed within 20%. This approach is impacted by variability in the maximum quantum yield (ϕmax) and the irradiance light-saturation parameter (Ek(PAR)). An analysis of available data shows that ϕmax variability is relatively constrained in temperate waters. The variability of Ek(PAR) is greater in temperate waters, but based on a sensitivity analysis, has an overall smaller impact on water-column-integrated productivity rates because of the exponential decay of light. This inversion approach illustrates the utility of bio-optical models in turbid coastal waters given the measurements of the bulk inherent optical properties.

  2. Regulation of intramembranous absorption and amniotic fluid volume by constituents in fetal sheep urine.

    PubMed

    Anderson, Debra F; Jonker, Sonnet S; Louey, Samantha; Cheung, Cecilia Y; Brace, Robert A

    2013-09-01

    Our objective was to test the hypothesis that fetal urine contains a substance(s) that regulates amniotic fluid volume by altering the rate of intramembranous absorption of amniotic fluid. In late gestation ovine fetuses, amniotic fluid volumes, urine, and lung liquid production rates, swallowed volumes and intramembranous volume and solute absorption rates were measured over 2-day periods under control conditions and when urine was removed and continuously replaced at an equal rate with exogenous fluid. Intramembranous volume absorption rate decreased by 40% when urine was replaced with lactated Ringer solution or lactated Ringer solution diluted 50% with water. Amniotic fluid volume doubled under both conditions. Analysis of the intramembranous sodium and chloride fluxes suggests that the active but not passive component of intramembranous volume absorption was altered by urine replacement, whereas both active and passive components of solute fluxes were altered. We conclude that fetal urine contains an unidentified substance(s) that stimulates active intramembranous transport of amniotic fluid across the amnion into the underlying fetal vasculature and thereby functions as a regulator of amniotic fluid volume.

  3. Assessment of absorption potential of poorly water-soluble drugs by using the dissolution/permeation system.

    PubMed

    Kataoka, Makoto; Yano, Koji; Hamatsu, Yoriko; Masaoka, Yoshie; Sakuma, Shinji; Yamashita, Shinji

    2013-11-01

    This study aims to assess the absorption potential of oral absorption of poorly water-soluble drugs by using the dissolution/permeation system (D/P system). The D/P system can be used to perform analysis of drug permeation under dissolution process and can predict the fraction of absorbed dose in humans. When celecoxib at 1/100 of a clinical dose was applied to the D/P system, percentage of dose dissolved and permeated significantly decreased with an increase in the applied amount, resulting in the oral absorption being predicted to be 22-55%. Whereas similar dissolution and permeation profiles of montelukast sodium were observed, estimated absorption (69-85%) was slightly affected. Zafirlukast absorption (33-36%) was not significantly affected by the dose, although zafirlukast did not show complete dissolution. The relationship between clinical dose and predicted oral absorption of drugs corresponded well to clinical observations. The limiting step of the oral absorption of celecoxib and montelukast sodium was solubility, while that of zafirlukast was dissolution rate. However, due to high permeability of montelukast, oral absorption was not affected by dose. Therefore, the D/P system is a useful tool to assess the absorption potential of poorly water-soluble drugs for oral use.

  4. Assessment of absorption potential of poorly water-soluble drugs by using the dissolution/permeation system.

    PubMed

    Kataoka, Makoto; Yano, Koji; Hamatsu, Yoriko; Masaoka, Yoshie; Sakuma, Shinji; Yamashita, Shinji

    2013-11-01

    This study aims to assess the absorption potential of oral absorption of poorly water-soluble drugs by using the dissolution/permeation system (D/P system). The D/P system can be used to perform analysis of drug permeation under dissolution process and can predict the fraction of absorbed dose in humans. When celecoxib at 1/100 of a clinical dose was applied to the D/P system, percentage of dose dissolved and permeated significantly decreased with an increase in the applied amount, resulting in the oral absorption being predicted to be 22-55%. Whereas similar dissolution and permeation profiles of montelukast sodium were observed, estimated absorption (69-85%) was slightly affected. Zafirlukast absorption (33-36%) was not significantly affected by the dose, although zafirlukast did not show complete dissolution. The relationship between clinical dose and predicted oral absorption of drugs corresponded well to clinical observations. The limiting step of the oral absorption of celecoxib and montelukast sodium was solubility, while that of zafirlukast was dissolution rate. However, due to high permeability of montelukast, oral absorption was not affected by dose. Therefore, the D/P system is a useful tool to assess the absorption potential of poorly water-soluble drugs for oral use. PMID:23811221

  5. Preventing percutaneous absorption of industrial chemicals: the skin denotation

    SciTech Connect

    Grandjean, P.; Berlin, A.; Gilbert, M.; Penning, W.

    1988-01-01

    Percutaneous absorption has received comparatively little attention in occupational health, although this route of entry has repeatedly caused occupation-related intoxications. In practice, the evaluation of skin penetration rates is far from simple. Much evidence has been obtained from studies of chemicals used for cosmetics and topical therapeutics, but the information available on compounds encountered in occupational health is limited. The data obtained from experimental studies have confirmed that the concentration, type of vehicle, skin area, skin condition, and extent of occlusion are important factors in determining the degree of percutaneous absorption, but no general model has been developed. Also, too little is known about the basic chemical properties governing the rate of penetration. Thus, prediction is difficult and bound to be rather inaccurate. Current preventive practice follows the procedure used by ACGIH and is mainly based on a skin denotation in official listings of chemicals to which exposure limits have been allocated. The number of substances and groups of chemicals which have received skin denotation in 17 selected countries varies between 24 and 179 and a total of 275 are listed as a skin hazard in one or more countries; ACGIH lists 143. Thus, the denotation practice varies. As an unfortunate result of these discrepancies and the dichotomy of skin denotation, the absence of skin denotation may erroneously indicate that efforts to protect the skin are unnecessary. Thus, an evaluation of skin penetration potentials should be incorporated in occupational health practice as a supplement to the official denotations. 23 references.

  6. Super-Resonant Intracavity Coherent Absorption

    PubMed Central

    Malara, P.; Campanella, C. E.; Giorgini, A.; Avino, S.; De Natale, P.; Gagliardi, G.

    2016-01-01

    The capability of optical resonators to extend the effective radiation-matter interaction length originates from a multipass effect, hence is intrinsically limited by the resonator’s quality factor. Here, we show that this constraint can be overcome by combining the concepts of resonant interaction and coherent perfect absorption (CPA). We demonstrate and investigate super-resonant coherent absorption in a coupled Fabry-Perot (FP)/ring cavity structure. At the FP resonant wavelengths, the described phenomenon gives rise to split modes with a nearly-transparent peak and a peak whose transmission is exceptionally sensitive to the intracavity loss. For small losses, the effective interaction pathlength of these modes is proportional respectively to the ratio and the product of the individual finesse coefficients of the two resonators. The results presented extend the conventional definition of resonant absorption and point to a way of circumventing the technological limitations of ultrahigh-quality resonators in spectroscopy and optical sensing schemes. PMID:27364475

  7. Cavity induced perfect absorption in metamaterials

    NASA Astrophysics Data System (ADS)

    Luu Dang, Hong; Nguyen, Hoang Tung; Dung Nguyen, Van; Bui, Son Tung; Tuyen Le, Dac; Ngo, Quang Minh; Vu, Dinh Lam

    2016-03-01

    We present novel resonant modes at the THz regime in a structure combining conventional metamaterial absorber (MA) with a cavity (MAC). The well-known structure consisting of three individual layers of periodic metallic dishes on the top, a dielectric layer in the middle, and a metallic film in the bottom is used, and the cavity is formed on the top layer by changing the geometry of the metallic dishes. MACs with various cavity parameters are designed and their absorption characteristics, such as magnetic field distribution, surface current, and power loss density at resonant frequencies of the designed structure, are numerically investigated. Resonant effects in this work may find applications in THz tunable and broadband MA, and our investigation on the dependence of the absorption frequency and absorption intensity on the geometric cavity of the designed structure will provide a general guideline for MAC design.

  8. Subwavelength total acoustic absorption with degenerate resonators

    NASA Astrophysics Data System (ADS)

    Yang, Min; Meng, Chong; Fu, Caixing; Li, Yong; Yang, Zhiyu; Sheng, Ping

    2015-09-01

    We report the experimental realization of perfect sound absorption by sub-wavelength monopole and dipole resonators that exhibit degenerate resonant frequencies. This is achieved through the destructive interference of two resonators' transmission responses, while the matching of their averaged impedances to that of air implies no backscattering, thereby leading to total absorption. Two examples, both using decorated membrane resonators (DMRs) as the basic units, are presented. The first is a flat panel comprising a DMR and a pair of coupled DMRs, while the second one is a ventilated short tube containing a DMR in conjunction with a sidewall DMR backed by a cavity. In both examples, near perfect absorption, up to 99.7%, has been observed with the airborne wavelength up to 1.2 m, which is at least an order of magnitude larger than the composite absorber. Excellent agreement between theory and experiment is obtained.

  9. Super-Resonant Intracavity Coherent Absorption.

    PubMed

    Malara, P; Campanella, C E; Giorgini, A; Avino, S; De Natale, P; Gagliardi, G

    2016-01-01

    The capability of optical resonators to extend the effective radiation-matter interaction length originates from a multipass effect, hence is intrinsically limited by the resonator's quality factor. Here, we show that this constraint can be overcome by combining the concepts of resonant interaction and coherent perfect absorption (CPA). We demonstrate and investigate super-resonant coherent absorption in a coupled Fabry-Perot (FP)/ring cavity structure. At the FP resonant wavelengths, the described phenomenon gives rise to split modes with a nearly-transparent peak and a peak whose transmission is exceptionally sensitive to the intracavity loss. For small losses, the effective interaction pathlength of these modes is proportional respectively to the ratio and the product of the individual finesse coefficients of the two resonators. The results presented extend the conventional definition of resonant absorption and point to a way of circumventing the technological limitations of ultrahigh-quality resonators in spectroscopy and optical sensing schemes. PMID:27364475

  10. Super-Resonant Intracavity Coherent Absorption

    NASA Astrophysics Data System (ADS)

    Malara, P.; Campanella, C. E.; Giorgini, A.; Avino, S.; de Natale, P.; Gagliardi, G.

    2016-07-01

    The capability of optical resonators to extend the effective radiation-matter interaction length originates from a multipass effect, hence is intrinsically limited by the resonator’s quality factor. Here, we show that this constraint can be overcome by combining the concepts of resonant interaction and coherent perfect absorption (CPA). We demonstrate and investigate super-resonant coherent absorption in a coupled Fabry-Perot (FP)/ring cavity structure. At the FP resonant wavelengths, the described phenomenon gives rise to split modes with a nearly-transparent peak and a peak whose transmission is exceptionally sensitive to the intracavity loss. For small losses, the effective interaction pathlength of these modes is proportional respectively to the ratio and the product of the individual finesse coefficients of the two resonators. The results presented extend the conventional definition of resonant absorption and point to a way of circumventing the technological limitations of ultrahigh-quality resonators in spectroscopy and optical sensing schemes.

  11. Absorption technique for OH measurements and calibration

    NASA Technical Reports Server (NTRS)

    Bakalyar, D. M.; James, J. V.; Wang, C. C.

    1982-01-01

    An absorption technique is described which utilizes a stabilized frequency-doubled tunable dye laser and a long-path White cell with high mirror reflectivities both in the red and UV. In laboratory conditions it has been possible to routinely obtain a detection sensitivity of 3 parts in 1,000,000 over absorption paths less than 1 m in length and a detection sensitivity of approximately 6 parts in 100,000 over an absorption path of the order of 1 km. The latter number corresponds to 3,000,000 OH molecules/cu cm, and therefore the technique should be particularly useful for calibration the fluorescence instrument for OH measurements. However, the presence of atmospheric fluctuations coupled with intensity variation accompanying frequency scanning appears to degrade the detection sensitivity in outdoor ambient conditions, thus making it unlikely that this technique can be employed for direct OH monitoring.

  12. Demonstration of differential backscatter absorption gas imaging.

    PubMed

    Powers, P E; Kulp, T J; Kennedy, R

    2000-03-20

    Backscatter absorption gas imaging (BAGI) is a technique that uses infrared active imaging to generate real-time video imagery of gas plumes. We describe a method that employs imaging at two wavelengths (absorbed and not absorbed by the gas to be detected) to allow wavelength-differential BAGI. From the frames collected at each wavelength, an absorbance image is created that displays the differential absorbance of the atmosphere between the imager and the backscatter surface. This is analogous to a two-dimensional topographic differential absorption lidar or differential optical absorption spectroscopy measurement. Gas plumes are displayed, but the topographic scene image is removed. This allows a more effective display of the plume image, thus ensuring detection under a wide variety of conditions. The instrument used to generate differential BAGI is described. Data generated by the instrument are presented and analyzed to estimate sensitivity. PMID:18338030

  13. Rotational averaging of multiphoton absorption cross sections

    SciTech Connect

    Friese, Daniel H. Beerepoot, Maarten T. P.; Ruud, Kenneth

    2014-11-28

    Rotational averaging of tensors is a crucial step in the calculation of molecular properties in isotropic media. We present a scheme for the rotational averaging of multiphoton absorption cross sections. We extend existing literature on rotational averaging to even-rank tensors of arbitrary order and derive equations that require only the number of photons as input. In particular, we derive the first explicit expressions for the rotational average of five-, six-, and seven-photon absorption cross sections. This work is one of the required steps in making the calculation of these higher-order absorption properties possible. The results can be applied to any even-rank tensor provided linearly polarized light is used.

  14. Absorption and fluorescence spectroscopy on a smartphone

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Arafat; Canning, John; Cook, Kevin; Ast, Sandra; Rutledge, Peter J.; Jamalipour, Abbas

    2015-07-01

    A self-powered smartphone-based field-portable "dual" spectrometer has been developed for both absorption and fluorescence measurements. The smartphone's existing flash LED has sufficient optical irradiance to undertake absorption measurements within a 3D-printed case containing a low cost nano-imprinted polymer diffraction grating. A UV (λex ~ 370 nm) and VIS (λex ~ 450 nm) LED are wired into the circuit of the flash LED to provide an excitation source for fluorescence measurements. Using a customized app on the smartphone, measurements of absorption and fluorescence spectra are demonstrated using pH-sensitive and Zn2+-responsive probes. Detection over a 300 nm span with 0.42 nm/pixel spectral resolution is demonstrated. Despite the low cost and small size of the portable spectrometer, the results compare well with bench top instruments.

  15. Laser absorption phenomena in flowing gas devices

    NASA Technical Reports Server (NTRS)

    Chapman, P. K.; Otis, J. H.

    1976-01-01

    A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

  16. Broadband absorption engineering of hyperbolic metafilm patterns

    NASA Astrophysics Data System (ADS)

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-03-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experimental realization of an on-chip broadband super absorber structure based on hyperbolic metamaterial waveguide taper array with strong and tunable absorption profile from near-infrared to mid-infrared spectral region. The ability to efficiently produce broadband, highly confined and localized optical fields on a chip is expected to create new regimes of optical/thermal physics, which holds promise for impacting a broad range of energy technologies ranging from photovoltaics, to thin-film thermal absorbers/emitters, to optical-chemical energy harvesting.

  17. Broadband absorption engineering of hyperbolic metafilm patterns.

    PubMed

    Ji, Dengxin; Song, Haomin; Zeng, Xie; Hu, Haifeng; Liu, Kai; Zhang, Nan; Gan, Qiaoqiang

    2014-01-01

    Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experimental realization of an on-chip broadband super absorber structure based on hyperbolic metamaterial waveguide taper array with strong and tunable absorption profile from near-infrared to mid-infrared spectral region. The ability to efficiently produce broadband, highly confined and localized optical fields on a chip is expected to create new regimes of optical/thermal physics, which holds promise for impacting a broad range of energy technologies ranging from photovoltaics, to thin-film thermal absorbers/emitters, to optical-chemical energy harvesting. PMID:24675706

  18. Plasmon absorption modulator systems and methods

    DOEpatents

    Kekatpure, Rohan Deodatta; Davids, Paul

    2014-07-15

    Plasmon absorption modulator systems and methods are disclosed. A plasmon absorption modulator system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and a metal layer formed on a top surface of the stack of quantum well layers. A method for modulating plasmonic current includes enabling propagation of the plasmonic current along a metal layer, and applying a voltage across the stack of quantum well layers to cause absorption of a portion of energy of the plasmonic current by the stack of quantum well layers. A metamaterial switching system includes a semiconductor substrate, a plurality of quantum well layers stacked on a top surface of the semiconductor substrate, and at least one metamaterial structure formed on a top surface of the stack of quantum well layers.

  19. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to determine the aerosol Angstrom absorption exponents by linear regression. Since, unlike other absorbing aerosol species (e.g. humic like substances, nitrated PAHs), black carbon absorption is relatively constant from the ultraviolet to the infrared with an Angstrom absorption exponent of -1 (1), a comparison of the Angstrom exponents can indicate the presence of aerosol components with an enhanced UV absorption over that expected from BC content alone. The Angstrom exponents determined from the aerosol absorption measurements obtained in the field varied from - 0.7 to - 1.3 during the study and was generally lower in the afternoon than the morning hours, indicating an increase in secondary aerosol formation and photochemically generated UV absorbing species in the afternoon. Twelve-hour integrated samples of fine atmospheric aerosols (<0.1micron) were also collected at site T0 and T1 (Universidad Technologica de Tecamac, State of Mexico) from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. Samples were collected on quartz fiber filters with high volume impactor samplers. Continuous absorption spectra of these aerosol samples have been obtained in the laboratory from 280 to 900nm with the use of an integrating sphere coupled to a UV spectrometer (Beckman DU with a Labsphere accessory). The integrating sphere allows the detector to collect and spatially integrate the total radiant flux reflected from the sample and therefore allows for the measurement of absorption on highly reflective or diffusely scattering samples. These continuous spectra have also been used to obtain the

  20. Properties of quasar broad absorption line outflows

    NASA Astrophysics Data System (ADS)

    Capellupo, Daniel Moshin

    2012-06-01

    gas and cloud movements across our lines-of-sight. Part of the BAL monitoring programme specifically focused on obtaining multiple observations at rest-frame time-scales <1 month in order to determine whether there is a minimum time-scale threshold below which there is no variability. The shortest variability time-scales help determine how close to the central SMBH this outflowing gas can be located. I detect variability down to a rest-frame time-scale of ˜0.02 yr (8--10 days), which constrains the location of the outflowing gas from the central super-massive black hole in these systems down to sub-parsec scales. Finally, in order to determine the viability of quasar outflows as a feedback mechanism affecting galaxy evolution, we need estimates of their mass outflow rates and kinetic energy yields. These quantities depend on the column densities of the flows, which are difficult to obtain directly from spectra of the BALs. We turn to a low-abundance species, P V lambda1118, 1128. Phosphorus is much less abundant than, for example, carbon (P/C ˜ 0.001 in the Sun), so a detection of a P V BAL indicates that other lines, such as C IV, are saturated. We detect variability in a P V BAL in Q1413+1143, corresponding to variable Si IV and C IV BALs. The variability in the P V BAL confirms that the absorption is intrinsic to the quasar and provides a constraint on the location of the gas. Using the apparent optical depth of the P V BAL and photoionization models to constrain the true column density of the outflow, we estimate the kinetic energy yields and compare to simulations to find that this outflow could likely be a viable feedback mechanism.

  1. Strong associated C 4 absorption in low redshift quasars

    NASA Technical Reports Server (NTRS)

    Tytler, David

    1990-01-01

    IUE spectra of quasars were used to determine the frequency of occurrence of strong associated C 4 absorption systems at low red shifts. Four systems are found with rest frame equivalent width (REW) greater than 5 angstroms in the spectra of 38 quasars. This rate of occurrence of 0.12 is not significantly different from the rate of 0.064 determined for high red shift quasars. The detected strong associated systems are all in low red shift quasars which have been imaged from the ground. One of the quasars is unusual, having two nuclei, a close companion and distorted isotopes. Two of the others also have close companion galaxies at projected distances of under 100 kpc. The conclusion was made that a much larger sample is needed.

  2. Iron absorption and transport-an update.

    PubMed

    Conrad, M E; Umbreit, J N

    2000-08-01

    Iron is vital for all living organisms. However, excess iron is hazardous because it produces free radical formation. Therefore, iron absorption is carefully regulated to maintain an equilibrium between absorption and body loss of iron. In countries where heme is a significant part of the diet, most body iron is derived from dietary heme iron because heme binds few of the luminal intestinal iron chelators that inhibit absorption of non-heme iron. Uptake of luminal heme into enterocytes occurs as a metalloporphyrin. Intracellularly, iron is released from heme by heme oxygenase so that iron leaves the enterocyte to enter the plasma as non-heme iron. Ferric iron is absorbed via a beta(3) integrin and mobilferrin (IMP) pathway that is not shared with other nutritional metals. Ferrous iron uptake is facilitated by DMT-1 (Nramp-2, DCT-1) in a pathway shared with manganese. Other proteins were recently described which are believed to play a role in iron absorption. SFT (Stimulator of Iron Transport) is postulated to facilitate both ferric and ferrous iron uptake, and Hephaestin is thought to be important in transfer of iron from enterocytes into the plasma. The iron concentration within enterocytes reflects the total body iron and either upregulates or satiates iron-binding sites on regulatory proteins. Enterocytes of hemochromatotics are iron-depleted similarly to the absorptive cells of iron-deficient subjects. Iron depletion, hemolysis, and hypoxia each can stimulate iron absorption. In non-intestinal cells most iron uptake occurs via either the classical clathrin-coated pathway utilizing transferrin receptors or the poorly defined transferrin receptor independent pathway. Non-intestinal cells possess the IMP and DMT-1 pathways though their role in the absence of iron overload is unclear. This suggests that these pathways have intracellular functions in addition to facilitating iron uptake.

  3. Potassium emission absorption system. Topical report 12

    SciTech Connect

    Bauman, L.E.

    1995-04-01

    The Potassium Emission Absorption System is one of the advanced optical diagnostics developed at Mississippi State University to provide support for the demonstration of prototype-scale coal-fired combustion magnetohydrodynamic (MHD) electrical power generation. Intended for application in the upstream of an MHD flow, the system directly measures gas temperature and neutral potassium atom number density through spectroscopic emission absorption techniques. From these measurements the electron density can be inferred from a statistical equilibrium calculation and the electron conductivity in the MHD channel found by use of an electron mobility model. The instrument has been utilized for field test measurements on MHD facilities for almost a decade and has been proven to provide useful measurements as designed for MHD nozzle, channel, and diffuser test sections. The theory of the measurements, a system description, its capabilities, and field test measurement results are reported here. During the development and application of the instrument several technical issues arose which when addressed advanced the state of the art in emission absorption measurement. Studies of these issues are also reported here and include: two-wavelength measurements for particle-laden flows, potassium D-line far wing absorption coefficient, bias in emission absorption measurements arising from dirty windows and misalignments, non-coincident multiwavelength emission absorption sampling errors, and lineshape fitting for boundary layer flow profile information. Although developed for NLHD application, the instrument could be applied to any high temperature flow with a resonance line in the 300 to 800 nm range, for instance other types of flames, rocket plumes or low temperature plasmas.

  4. Aerosol optical absorption measurements with photoacoustic spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Wang, Lei; Liu, Qiang; Wang, Guishi; Tan, Tu; Zhang, Weijun; Chen, Weidong; Gao, Xiaoming

    2015-04-01

    Many parameters related to radiative forcing in climate research are known only with large uncertainties. And one of the largest uncertainties in global radiative forcing is the contribution from aerosols. Aerosols can scatter or absorb the electromagnetic radiation, thus may have negative or positive effects on the radiative forcing of the atmosphere, respectively [1]. And the magnitude of the effect is directly related to the quantity of light absorbed by aerosols [2,3]. Thus, sensitivity and precision measurement of aerosol optical absorption is crucial for climate research. Photoacoustic spectroscopy (PAS) is commonly recognized as one of the best candidates to measure the light absorption of aerosols [4]. A PAS based sensor for aerosol optical absorption measurement was developed. A 532 nm semiconductor laser with an effective power of 160 mW was used as a light source of the PAS sensor. The PAS sensor was calibrated by using known concentration NO2. The minimum detectable optical absorption coefficient (OAC) of aerosol was determined to be 1 Mm-1. 24 hours continues measurement of OAC of aerosol in the ambient air was carried out. And a novel three wavelength PAS aerosol OAC sensor is in development for analysis of aerosol wavelength-dependent absorption Angstrom coefficient. Reference [1] U. Lohmann and J. Feichter, Global indirect aerosol effects: a review, Atmos. Chem. Phys. 5, 715-737 (2005) [2] M. Z. Jacobson, Strong radiative heating due to the mixing state of black carbon in atmospheric aerosols, Nature 409, 695-697 (2001) [3] V. Ramanathan and G. Carmichae, Global and regional climate changes due to black carbon, nature geoscience 1, 221-227 (2008) [4] W.P Arnott, H. Moosmuller, C. F. Rogers, T. Jin, and R. Bruch, Photoacoustic spectrometer for measuring light absorption by aerosol: instrument description. Atmos. Environ. 33, 2845-2852 (1999).

  5. THE ABSORPTION SPECTRUM OF VISUAL PURPLE

    PubMed Central

    Chase, Aurin M.; Haig, Charles

    1938-01-01

    The absorption spectra of visual purple solutions extracted by various means were measured with a sensitive photoelectric spectrophotometer and compared with the classical visual purple absorption spectrum. Hardening the retinas in alum before extraction yielded visual purple solutions of much higher light transmission in the blue and violet, probably because of the removal of light-dispersing substances. Re-extraction indicated that visual purple is more soluble in the extractive than are the other colored retinal components. However, the concentration of the extractive did not affect the color purity of the extraction but did influence the keeping power. This suggests a chemical combination between the extractive and visual purple. The pH of the extractive affected the color purity of the resulting solution. Over the pH range from 5.5 to 10.0, the visual purple color purity was greatest at the low pH. Temperature during extraction was also effective, the color purity being greater the higher the temperature, up to 40°C. Drying and subsequent re-dissolving of visual purple solutions extracted with digitalin freed the solution of some protein impurities and increased its keeping power. Dialysis against distilled water seemed to precipitate visual purple from solution irreversibly. None of the treatments described improved the symmetry of the unbleached visual purple absorption spectrum sufficiently for it to resemble the classical absorption spectrum. Therefore it is very likely that the classical absorption spectrum is that of the light-sensitive group only and that the absorption spectra of our purest unbleached visual purple solutions represent the molecule as a whole. PMID:19873058

  6. Subbarrier absorption in a stationary superlattice

    NASA Technical Reports Server (NTRS)

    Arutyunyan, G. M.; Nerkararyan, K. V.

    1984-01-01

    The calculation of the interband absorption coefficient was carried out in the classical case, when the frequency of light was assumed to bind two miniband subbarrier states of different bands. The influence of two dimensional Mott excitons on this absorption was studied and a comparison was made with the experiment. All of these considerations were done taking into account the photon wave vector (the phase spatial heterogeneity). The basic traits of the energy spectra of superlattice semiconductors, their kinetic and optical properties, and possible means of electromagnetic wave intensification were examined. By the density matrix method, a theory of electrical and electromagnetic properties of superlattices was suggested.

  7. XUV Absorption by Solid Density Aluminum

    SciTech Connect

    Iglesias, C A

    2009-09-21

    An inverse bremsstrahlung model for plasmas and simple metals that approximates the cold, solid Al experimental data below the L-edge is applied to matter conditions relevant to XUV laser applications. The model involves an all-order calculation using a semi-analytical effective electron-ion interaction. The predicted increases in XUV absorption with rising temperature occur via two effects: increased availability of final states from reduced electron degeneracy and a stronger electron-ion interaction from reduced screening. Discrepancies in the temperature dependence as well as other details between the present approach and a recently proposed absorption model are discussed.

  8. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  9. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  10. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  11. Absorption spectroscopy: technique provides extremely high sensitivity.

    PubMed

    Provencal, R A; Paul, J B; Michael, E; Saykally, R J

    1998-06-01

    Technology associated with cavity ringdown laser absorption spectroscopy is reviewed. The technique is used to study general trace analysis, free radicals in flames and chemical reactors, molecular ions in electrical discharges, biological molecules and water clusters in supersonic jets, and vibrational overtones of stable molecules. Its specific enough to detect about 1-ppm fractional absorption by a gaseous sample in about 10 microseconds. The use of mirrors in ringdown sepctroscopy is explained. Other topics include the generation of pulsed infrared rays and the adaptation of ringdown spectroscopy for use with narrow-bandwidth continuous-wave lasers. PMID:11541906

  12. Maximum profit performance of an absorption refrigerator

    SciTech Connect

    Chen, L.; Sun, F.; Wu, C.

    1996-12-01

    The operation of an absorption refrigerator is viewed as a production process with exergy as its output. The relations between the optimal profit and COP (coefficient of performance), and the COP bound at the maximum profit of the refrigerator are derived based on a general heat transfer law. The results provide a theoretical basis for developing and utilizing a variety of absorption refrigerators. The focus of this paper is to search the compromise optimization between economics (profit) and the utilization factor (COP) for finite-time endoreversible thermodynamic cycles.

  13. Triplet absorption spectroscopy and electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Ghafoor, F.; Nazmitdinov, R. G.

    2016-09-01

    Coherence phenomena in a four-level atomic system, cyclically driven by three coherent fields, are investigated thoroughly at zero and weak magnetic fields. Each strongly interacting atomic state is converted to a triplet due to a dynamical Stark effect. Two dark lines with a Fano-like profile arise in the triplet absorption spectrum with anomalous dispersions. We provide conditions to control the widths of the transparency windows by means of the relative phase of the driving fields and the intensity of the microwave field, which closes the optical system loop. The effect of Doppler broadening on the results of the triplet absorption spectroscopy is analysed in detail.

  14. Light absorption in conical silicon particles.

    PubMed

    Bogdanowicz, J; Gilbert, M; Innocenti, N; Koelling, S; Vanderheyden, B; Vandervorst, W

    2013-02-11

    The problem of the absorption of light by a nanoscale dielectric cone is discussed. A simplified solution based on the analytical Mie theory of scattering and absorption by cylindrical objects is proposed and supported by the experimental observation of sharply localized holes in conical silicon tips after high-fluence irradiation. This study reveals that light couples with tapered objects dominantly at specific locations, where the local radius corresponds to one of the resonant radii of a cylindrical object, as predicted by Mie theory.

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

    NASA Technical Reports Server (NTRS)

    Chou, M. D.

    1980-01-01

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

  16. Hummingbirds rely on both paracellular and carrier-mediated intestinal glucose absorption to fuel high metabolism.

    PubMed

    McWhorter, Todd J; Bakken, Bradley Hartman; Karasov, William H; del Rio, Carlos Martínez

    2006-03-22

    Twenty years ago, the highest active glucose transport rate and lowest passive glucose permeability in vertebrates were reported in Rufous and Anna's hummingbirds (Selasphorus rufus, Calypte anna). These first measurements of intestinal nutrient absorption in nectarivores provided an unprecedented physiological foundation for understanding their foraging ecology. They showed that physiological processes are determinants of feeding behaviour. The conclusion that active, mediated transport accounts for essentially all glucose absorption in hummingbirds influenced two decades of subsequent research on the digestive physiology and nutritional ecology of nectarivores. Here, we report new findings demonstrating that the passive permeability of hummingbird intestines to glucose is much higher than previously reported, suggesting that not all sugar uptake is mediated. Even while possessing the highest active glucose transport rates measured in vertebrates, hummingbirds must rely partially on passive non-mediated intestinal nutrient absorption to meet their high mass-specific metabolic demands.

  17. Engineering non-radiative anapole modes for broadband absorption enhancement of light.

    PubMed

    Wang, Ren; Dal Negro, Luca

    2016-08-22

    In this paper, we propose a novel, frequency- and angularly- broadband approach to achieve absorption rate enhancement in high-index dielectric nanostructures through the engineering of non-radiative anapole modes. We employ multipolar decomposition of numerically computed current distributions and analyze the far-field scattering power of multipole moments. By leveraging the destructive interference of electric dipole and toroidal dipole moments, we design non-radiating anapole modes and demonstrate significantly enhanced absorbed power in silicon and germanium nanostructures. We demonstrate wide wavelength tunability of the anapole-driven peak absorption enhancement for nano-disks and square nano-pixel geometries, which can be conveniently fabricated with current lithography. Finally, by combining nano-disks and nano-pixels of different sizes into functional surface units, we design nanostructured arrays with enhanced bandwidth and absorption rates that can be useful for the engineering of broadband semiconductor photodetectors driven by controllable anapole responses. PMID:27557185

  18. Engineering non-radiative anapole modes for broadband absorption enhancement of light.

    PubMed

    Wang, Ren; Dal Negro, Luca

    2016-08-22

    In this paper, we propose a novel, frequency- and angularly- broadband approach to achieve absorption rate enhancement in high-index dielectric nanostructures through the engineering of non-radiative anapole modes. We employ multipolar decomposition of numerically computed current distributions and analyze the far-field scattering power of multipole moments. By leveraging the destructive interference of electric dipole and toroidal dipole moments, we design non-radiating anapole modes and demonstrate significantly enhanced absorbed power in silicon and germanium nanostructures. We demonstrate wide wavelength tunability of the anapole-driven peak absorption enhancement for nano-disks and square nano-pixel geometries, which can be conveniently fabricated with current lithography. Finally, by combining nano-disks and nano-pixels of different sizes into functional surface units, we design nanostructured arrays with enhanced bandwidth and absorption rates that can be useful for the engineering of broadband semiconductor photodetectors driven by controllable anapole responses.

  19. Effect of cadmium and chromium on the intestinal absorption of glucose in the snakehead fish, Channa punctatus.

    PubMed

    Sastry, K V; Sunita, K

    1982-02-01

    The effect of five concentrations of cadmium and chromium (10 mM, 1 mM, 0.1 mM, 0.01 mM and 0.001 mM) on the rate of absorption of glucose from the intestine of te snakehead fish, channa punctatus, was studied at 23 degrees C. All concentrations of cadmium decreased the rate of glucose transport. Maximum decrease was recorded with 10 mM of cadmium. The rate of transport decreased with an increase in the concentration of cadmium used. Chromium increased glucose absorption rate at all concentrations examined; the highest rate of absorption occurred at 0.001 mM of chromium.

  20. In vitro predictions of skin absorption of caffeine, testosterone, and benzoic acid: a multi-centre comparison study.

    PubMed

    van de Sandt, J J M; van Burgsteden, J A; Cage, S; Carmichael, P L; Dick, I; Kenyon, S; Korinth, G; Larese, F; Limasset, J C; Maas, W J M; Montomoli, L; Nielsen, J B; Payan, J-P; Robinson, E; Sartorelli, P; Schaller, K H; Wilkinson, S C; Williams, F M

    2004-06-01

    To obtain better insight into the robustness of in vitro percutaneous absorption methodology, the intra- and inter-laboratory variation in this type of study was investigated in 10 European laboratories. To this purpose, the in vitro absorption of three compounds through human skin (9 laboratories) and rat skin (1 laboratory) was determined. The test materials were benzoic acid, caffeine, and testosterone, representing a range of different physico-chemical properties. All laboratories performed their studies according to a detailed protocol in which all experimental details were described and each laboratory performed at least three independent experiments for each test chemical. All laboratories assigned the absorption of benzoic acid through human skin, the highest ranking of the three compounds (overall mean flux of 16.54+/-11.87 microg/cm(2)/h). The absorption of caffeine and testosterone through human skin was similar, having overall mean maximum absorption rates of 2.24+/-1.43 microg/cm(2)/h and 1.63+/-1.94 microg/cm(2)/h, respectively. In 7 out of 9 laboratories, the maximum absorption rates of caffeine were ranked higher than testosterone. No differences were observed between the mean absorption through human skin and the one rat study for benzoic acid and testosterone. For caffeine the maximum absorption rate and the total penetration through rat skin were clearly higher than the mean value for human skin. When evaluating all data, it appeared that no consistent relation existed between the diffusion cell type and the absorption of the test compounds. Skin thickness only slightly influenced the absorption of benzoic acid and caffeine. In contrast, the maximum absorption rate of testosterone was clearly higher in the laboratories using thin, dermatomed skin membranes. Testosterone is the most lipophilic compound and showed also a higher presence in the skin membrane after 24 h than the two other compounds. The results of this study indicate that the in