WorldWideScience

Sample records for absorption model

  1. Absorption in dielectric models

    CERN Document Server

    Churchill, R J

    2015-01-01

    We develop a classical microscopic model of a dielectric. The model features nonlinear interaction terms between polarizable dipoles and lattice vibrations. The lattice vibrations are found to act as a pseudo-reservoir, giving broadband absorption of electromagnetic radiation without the addition of damping terms in the dynamics. The effective permittivity is calculated using a perturbative iteration method and is found to have the form associated with real dielectrics. Spatial dispersion is naturally included in the model and we also calculate the wavevector dependence of the permittivity.

  2. Infrared absorption modeling of VOx microbolometer

    Science.gov (United States)

    Aggoun, Mehdi; Jiang, Jianliang; Khan, M. K.

    2015-08-01

    The absorption model plays an important role in the design of the microbolometer structure regarding the determination of the optimum thickness of the structure layers. Moreover, the infrared absorption depends on the wavelength of the radiation and the material properties. In this paper, we presented an Infrared absorption model with absorption coefficient of 96% at maximum absorption wavelength of 9.89μm which is very close to the expected value 10μm. This model was established by using MATLAB so that the simulation of the infrared absorption of the VOx microbolometer could be accomplished. In order to confirm the role of this modeling in the design of the device structure, comparison with other structures is also studied in this paper.

  3. In Silico Modeling of Gastrointestinal Drug Absorption: Predictive Performance of Three Physiologically Based Absorption Models.

    Science.gov (United States)

    Sjögren, Erik; Thörn, Helena; Tannergren, Christer

    2016-06-01

    Gastrointestinal (GI) drug absorption is a complex process determined by formulation, physicochemical and biopharmaceutical factors, and GI physiology. Physiologically based in silico absorption models have emerged as a widely used and promising supplement to traditional in vitro assays and preclinical in vivo studies. However, there remains a lack of comparative studies between different models. The aim of this study was to explore the strengths and limitations of the in silico absorption models Simcyp 13.1, GastroPlus 8.0, and GI-Sim 4.1, with respect to their performance in predicting human intestinal drug absorption. This was achieved by adopting an a priori modeling approach and using well-defined input data for 12 drugs associated with incomplete GI absorption and related challenges in predicting the extent of absorption. This approach better mimics the real situation during formulation development where predictive in silico models would be beneficial. Plasma concentration-time profiles for 44 oral drug administrations were calculated by convolution of model-predicted absorption-time profiles and reported pharmacokinetic parameters. Model performance was evaluated by comparing the predicted plasma concentration-time profiles, Cmax, tmax, and exposure (AUC) with observations from clinical studies. The overall prediction accuracies for AUC, given as the absolute average fold error (AAFE) values, were 2.2, 1.6, and 1.3 for Simcyp, GastroPlus, and GI-Sim, respectively. The corresponding AAFE values for Cmax were 2.2, 1.6, and 1.3, respectively, and those for tmax were 1.7, 1.5, and 1.4, respectively. Simcyp was associated with underprediction of AUC and Cmax; the accuracy decreased with decreasing predicted fabs. A tendency for underprediction was also observed for GastroPlus, but there was no correlation with predicted fabs. There were no obvious trends for over- or underprediction for GI-Sim. The models performed similarly in capturing dependencies on dose and

  4. Strong absorption model analysis of alpha scattering

    International Nuclear Information System (INIS)

    Angular distribution of alpha-particles at several energies, Eα = 21 ∼ 85.6 MeV from a number of nuclei between 20Ni and 119Sn, extending to wide angular range up to ∼ 160 deg. C in some cases, have been analyzed in terms of three-parameter strong absorption model of Frahn and Venter. Interaction radius and surface diffuseness are obtained from the parameter values rendering the best fit to the elastic scattering data. The inelastic scattering of alpha-particles from a number of nuclei, leading to quadrupole and octupole excitations has also been studied giving the deformation parameters βL. (author). 14 refs, 7 figs, 3 tabs

  5. Absorptive Capacity of Information Technology and Its Conceptual Model

    Institute of Scientific and Technical Information of China (English)

    BI Xinhua; YU Cuiling

    2008-01-01

    In order to examine the problem of how to improve the use of information technology (IT) in enterprises, this paper makes an exploration from the perspective of organizational absorptive capacity. We propose the concept of IT absorptive capacity from an organizational level. A dynamic process model is developed to further analyze IT absorption. IT absorptive capacity of this process is embodied as six forms: identification, adoption, adaptation, acceptance, infusion, and knowledge management. By means of questionnaire surveys of 76 Chinese enterprises, the main factors that favor or disable the capacity of each stage are discovered. Using the method of system dynamics, a conceptual model of IT absorptive capacity is developed to analyze the action mechanism of the factors in detail. The model indicates that the critical factors are embodied in the aspect of management. Furthermore, it demonstrates that IT absorption is a spiral process, during which IT absorptive capacity evolves dynamically and, consequently, promotes IT use.

  6. Modeling water/lithium bromide absorption chillers in ASPEN Plus

    International Nuclear Information System (INIS)

    Highlights: → Single- and double-effect water/lithium bromide absorption chiller designs are numerically modeled using ASPEN. → The modeling procedure is described and the results are compared to published modeling data to access prediction accuracy. → Predictions for the single- and double-effect designs are within 3% and 5%, respectively of published data for all cycle parameters of interest. → The absorption cycle models presented allow investigation of using absorption chillers for waste heat utilization in the oil and gas industry. -- Abstract: Absorption chillers are a viable option for providing waste heat-powered cooling or refrigeration in oil and gas processing plants, thereby improving energy efficiency. In this paper, single- and double-effect water/lithium bromide absorption chiller designs are numerically modeled using ASPEN. The modeling procedure is described and the results are compared to published modeling data to access prediction accuracy. Predictions for the single- and double-effect designs are within 3% and 5%, respectively of published data for all cycle parameters of interest. The absorption cycle models presented not only allow investigation into the benefits of using absorption chillers for waste heat utilization in the oil and gas industry, but are also generically applicable to a wide range of other applications.

  7. Modelling absorption and photoluminescence of TPD

    Energy Technology Data Exchange (ETDEWEB)

    Vragovic, Igor [Dpto. de Fisica Aplicada and Inst. Universitario de Materiales de Alicante, Universidad de Alicante, E-03080 Alicante (Spain)], E-mail: igor.vragovic@ua.es; Calzado, Eva M.; Diaz Garcia, Maria A.; Himcinschi, C. [Max-Planck-Institut fuer Mikrostrukturphysik, D-06120 Halle (Germany); Gisslen, L.; Scholz, R. [Walter Schottky Institut, Technische Universitaet Muenchen, D-85748 Garching (Germany)

    2008-05-15

    We analyse the optical spectra of N,N{sup '}-diphenyl-N,N{sup '}-bis(3-methyl-phenyl)-(1,1{sup '}-biphenyl)-4,4{sup '}-diamine (TPD) doped polystyrene films. The aim of the present paper is to give a microscopic interpretation of the significant Stokes shift between absorption and photoluminescence, which makes this material suitable for stimulated emission. The optimized geometric structures and energies of a neutral TPD monomer in ground and excited states are obtained by ab initio calculations using Hartree-Fock and density functional theory. The results indicate that the second distinct peak observed in absorption may arise either from a group of higher electronic transitions of the monomer or from the lowest optical transitions of a TPD dimer.

  8. Estimation of the Human Absorption Cross Section Via Reverberation Models

    DEFF Research Database (Denmark)

    Steinböck, Gerhard; Pedersen, Troels; Fleury, Bernard Henri;

    2016-01-01

    Since the presence of persons affects the reverberation time observed for in-room channels, the absorption cross section of a person can be estimated from measurements via Sabine's and Eyring's models for the reverberation time. We propose an estimator relying on the more accurate model by Eyring...... and compare the obtained results to those of Sabine's model. We find that the absorption by persons is large enough to be measured with a wideband channel sounder and that estimates of the human absorption cross section differ for the two models. The obtained values are comparable to values reported...... in the literature. We also suggest the use of controlled environments with low average absorption coefficients to obtain more reliable estimates. The obtained values can be used to predict the change of reverberation time with persons in the propagation environment. This allows prediction of channel characteristics...

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

    Science.gov (United States)

    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

  10. Water Transport Models of Moisture Absorption and Sweat Discharge Yarns

    Institute of Scientific and Technical Information of China (English)

    WANG Fa-ming; ZHOU Xiao-hong; WANG Shan-yuan

    2008-01-01

    An important property of moisture absorption and sweat discharge yams is their water transport property. In the paper, two water transport models of moisture absorption and sweat discharge yams were developed to investigate the influence factors on their wicking rate. In parallel Column Pores Model, wicking rate is determined by the equivalent capillary radius R and length of the capillary tube L. In Pellets Accumulation Model, wicking rate is decided by the capillary radius r and length of the fiber unit assemble L0.

  11. Integro-differential models for percutaneous drug absorption

    OpenAIRE

    Barbeiro, S.; Ferreira, J. A.

    2007-01-01

    In this paper we propose new mathematical models for percutaneous absorption of a drug. The new models are established by introducing, in the classical Fick's law, a memory term being the advection–diffusion equations of the classical models replaced by integro-differential equations. The well-posedness of the models is studied with Dirichlet, Neumann and natural boundary conditions. Methods for the computation of numerical solutions are proposed. Stability and convergence of the introduced m...

  12. Model predicting impact of complexation with cyclodextrins on oral absorption.

    Science.gov (United States)

    Gamsiz, Ece D; Thombre, Avinash G; Ahmed, Imran; Carrier, Rebecca L

    2013-09-01

    Significant effort and resource expenditure is dedicated to enabling low-solubility oral drug delivery using solubilization technologies. Cyclodextrins (CD) are cyclic oligosaccharides which form inclusion complexes with many drugs and are often used as solubilizing agents. It is not clear prior to developing a drug delivery device with CD what level of absorption enhancement might be achieved; modeling can provide useful guidance in formulation and minimize resource intensive iterative formulation development. A model was developed to enable quantitative, dynamic prediction of the influence of CD on oral absorption of low solubility drug administered as a pre-formed complex. The predominant effects of CD considered were enhancement of dissolution and slowing of precipitation kinetics, as well as binding of free drug in solution. Simulation results with different parameter values reflective of typical drug and CD properties indicate a potential positive (up to five times increase in drug absorption), negative (up to 50% decrease in absorption) or lack of effect of CD. Comparison of model predictions with in vitro and in vivo experimental results indicate that a systems-based dynamic model incorporating CD complexation and key process kinetics may enable quantitative prediction of impact of CD delivered as a pre-formed complex on drug bioavailability.

  13. An Empirical Investigation into a Subsidiary Absorptive Capacity Process Model

    DEFF Research Database (Denmark)

    Schleimer, Stephanie; Pedersen, Torben

    2011-01-01

    literature. However, it remains to be surrounded by considerable ambiguity in terms of its actual meaning, the drivers influencing its evolution, and its impact on related outcomes. In this study, we take on some of the major criticisms and recent suggestions from the absorptive capacity literature...... and empirically test a process model of absorptive capacity. The setting of our empirical study is 213 subsidiaries of multinational enterprises and the focus is on the capacity of these subsidiaries to successfully absorb best practices in marketing strategy from their headquarters. This setting allows us...

  14. Compression-absorption (resorption) refrigerating machinery. Modeling of reactors; Machine frigorifique a compression-absorption (resorption). Modelisation des reacteurs

    Energy Technology Data Exchange (ETDEWEB)

    Lottin, O.; Feidt, M.; Benelmir, R. [LEMTA-UHP Nancy-1, 54 - Vandoeuvre-les-Nancy (France)

    1997-12-31

    This paper is a series of transparencies presenting a comparative study of the thermal performances of different types of refrigerating machineries: di-thermal with vapor compression, tri-thermal with moto-compressor, with ejector, with free piston, adsorption-type, resorption-type, absorption-type, compression-absorption-type. A prototype of ammonia-water compression-absorption heat pump is presented and modeled. (J.S.)

  15. Model galactic coronae: Ionization structure and absorption-line spectra

    International Nuclear Information System (INIS)

    We describe a general model for a gaseous galactic corona, and demonstrate that it is in harmony with a variety of observational and theoretical constraints. We then compute the ionization equilibria of H, He, C, N, O, Si, and S atoms in the corona and determine the strengths of resonance absorption lines arising therein. To this end, we obtain approximate cross sections for ionization of the heavy-element ions by photons of energy E/sub γ/< or =100 eV.We use our results first to discuss the expected absorption spectrum of our Galaxy's corona. Subsequently, we discuss in detail the relevance of our computed equilibria to the suggestion that galactic coronae produce some redshift systems in quasar absorption spectra. Because our model coronae are not isothermal, the ionization structure existing along various lines of sight through them is not in accord with the concept of ''reasonable ionization equilibrium'': a concept assumed to be valid in most analyses of quasar spectra. However, our calculations indicate that typically one well-established redshift system in each quasar absorption spectrum could arise in the corona of an intervening galaxy. This is the number expected from statistical arguments if quasar redshifts are fully cosmological in origin

  16. Ray tracing and ECRH absorption modeling in the HSX stellarator

    Science.gov (United States)

    Weir, G. M.; Likin, K. M.; Marushchenko, N. B.; Turkin, Y.

    2015-09-01

    To increase flexibility in ECRH experiments on the helically symmetric experiment (HSX), a second gyrotron and transmission line have been installed. The second antenna includes a steerable mirror for off-axis heating, and the launched power may be modulated for use in heat pulse propagation experiments. The extraordinary wave at the second harmonic of the electron gyrofrequency or the ordinary wave at the fundamental resonance are used for plasma start-up and heating on HSX. The tracing visualized ray tracing code (Marushchenko et al 2007 Plasma Fusion Res. 2 S1129) is used to estimate single-pass absorption and to model multi-pass wave damping in the three-dimensional HSX geometry. The single-pass absorption of the ordinary wave at the fundamental resonance is calculated to be as high as 30%, while measurements of the total absorption indicate that 45% of the launched power is absorbed. A multi-pass ray tracing model correctly predicts the experimental absorption and indicates that the launched power is absorbed within the plasma core (r/a≤slant 0.2 ).

  17. Intergalactic Helium Absorption in Cold Dark Matter Models

    CERN Document Server

    Croft, R A C; Katz, N; Hernquist, L E; Croft, Rupert A. C.; Weinberg, David H.; Katz, Neal; Hernquist, Lars

    1996-01-01

    Observations from the HST and the HUT have recently detected HeII absorption along the lines of sight to two high redshift quasars. We use cosmological simulations with gas dynamics to investigate HeII absorption in the cold dark matter (CDM) theory of structure formation. We consider two Omega=1 CDM models with different normalizations and one Omega_0=0.4 CDM model, all incorporating the photoionizing UV background spectrum computed by Haardt & Madau (1996). The simulated gas distribution, combined with the H&M spectral shape, accounts for the relative observed values of taubar_HI and taubar_HeII, the effective mean optical depths for HI and HeII absorption. If the background intensity is as high as H&M predict, then matching the absolute values of taubar_HI and taubar_HeII requires a baryon abundance larger (by factors between 1.5 and 3 for the various CDM models) than our assumed value of Omega_b h^2=0.0125. The simulations reproduce the evolution of taubar_heII over the observed redshift range...

  18. Mathematical Model of Natural Gas Desulfurization Based on Membrane Absorption

    Institute of Scientific and Technical Information of China (English)

    Wang Shuli; Ma Jun; Wang Ganyu; Zhou Heng

    2014-01-01

    Models of mass transfer kinetics combined with mass transfer differential equation and mass transfer resistance equation were established on the basis of double-iflm theory. Mass transfer process of H2S absorption by means of polypro-pylene hydrophobic microporous hollow ifber membrane contactor was simulated using MDEA (N-methyldiethanolamine) as the absorption liquid and corresponding experiments of natural gas desulfurization were performed. The simulation re-sults indicated that the removal rate of hydrogen sulifde showed positive dependence on the absorption liquid concentration and gas pressure. However, the desulfurization rate showed negative dependence on gas lfow. The simulated values were in good agreement with the experimental results. The in-tube concentration of hydrogen sulifde at the same point increased with increase in the gas velocity. Axial concentration of hydrogen sulifde decreased rapidly at the beginning, and the de-crease saw a slowdown during the latter half period. Hydrogen sulifde concentration dropped quickly in the radial direction, and the reduction in the radial direction was weakened with the increase of axial length due to the gradual reduction of hy-drogen sulifde concentration along the tube. The desulfurization rate under given operating conditions can be predicted by this model, and the theoretical basis for membrane module design can also be provided.

  19. Absorption lookup tables in the radiative transfer model ARTS

    International Nuclear Information System (INIS)

    We describe the lookup table approach that is used to store pre-calculated absorption data in the radiative transfer model ARTS. The table stores absorption cross sections as a function of frequency, pressure, temperature, and the water vapor volume mixing ratio, where the last dimension is only included for those gas species that require it. The table is used together with an extraction strategy, which uses polynomial interpolation, with recommended interpolation orders between five and seven. We also derived recommended default settings for grid spacings and interpolation orders, and verified that the approach gives very accurate results with these default settings. The tested instrument setups were for AMSU-B, HIRS, and Odin, three well-known satellite remote sensing instruments covering a wide range of frequencies and viewing geometries. Errors introduced by the lookup table were found to be always below a few millikelvin, in terms of the simulated brightness temperature.

  20. Models of ionospheric VLF absorption of powerful ground based transmitters

    OpenAIRE

    İnan, Umran Savaş; Cohen, M. B; Lehtinen, N. G

    2012-01-01

    Models of ionospheric VLF absorption of powerful ground based transmitters M. B. Cohen,1 N. G. Lehtinen,1 and U. S. Inan1,2 Received 5 November 2012; accepted 16 November 2012; published 29 December 2012. [1] Ground based Very Low Frequency (VLF, 3–30 kHz) radio transmitters play a role in precipitation of energetic Van Allen electrons. Initial analyses of the contribution of VLF transmitters to radiation belt losses were based on early models of trans-ionospheric prop...

  1. A dynamic model of digestion and absorption in pigs

    DEFF Research Database (Denmark)

    Strathe, Anders Bjerring; Danfær, Allan Christian; Chwalibog, Andrzej

    2008-01-01

    The paper describes and evaluates the construction of a mathematical model to study the kinetics of digestion and absorption in growing pigs. The core of the model is based on a compartmental structure, which divides the gastro-intestinal tract into four anatomical segments: the stomach, two parts...... of the small intestine and the large intestine. Within the large intestine, a microbial sub compartment is also considered. In each of these segments, the major organic nutrients are considered: dietary protein, endogenous protein, amino acids, non-amino acid and non-protein nitrogen, lipids, fatty acids...

  2. Absorption Cycle Heat Pump Model for Control Design

    DEFF Research Database (Denmark)

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard;

    2015-01-01

    Heat pumps have recently received increasing interest due to green energy initiatives and increasing energy prices. In this paper, a nonlinear dynamic model of a single-effect LiBr-water absorption cycle heat pump is derived for simulation and control design purposes. The model is based...... on an actual heat pump located at a larger district heating plant. The model is implemented in Modelica and is based on energy and mass balances, together with thermodynamic property functions for LiBr and water and staggered grid representations for heat exchangers. Model parameters have been fitted...... to operational data and different scenarios are simulated to investigate the operational stability of the heat pump. Finally, this paper provides suggestions and examples of derivation of lower order linear models for control design. © Copyright IEEE - All rights reserved....

  3. Modeling of light absorption in tissue during infrared neural stimulation.

    Science.gov (United States)

    Thompson, Alexander C; Wade, Scott A; Brown, William G A; Stoddart, Paul R

    2012-07-01

    A Monte Carlo model has been developed to simulate light transport and absorption in neural tissue during infrared neural stimulation (INS). A range of fiber core sizes and numerical apertures are compared illustrating the advantages of using simulations when designing a light delivery system. A range of wavelengths, commonly used for INS, are also compared for stimulation of nerves in the cochlea, in terms of both the energy absorbed and the change in temperature due to a laser pulse. Modeling suggests that a fiber with core diameter of 200 μm and NA=0.22 is optimal for optical stimulation in the geometry used and that temperature rises in the spiral ganglion neurons are as low as 0.1°C. The results show a need for more careful experimentation to allow different proposed mechanisms of INS to be distinguished.

  4. Magnetospheres of hot Jupiters: hydrodynamic models & ultraviolet absorption

    CERN Document Server

    Alexander, R D; Mohammed, H; Nichols, J D; Ercolano, B

    2015-01-01

    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 $\\simeq$1.6-1.8) so the shock is weak. This results in a characteristic signature in the ultraviolet light curve: a broad absorption feature that leads the optical transit by 10-20% in orbital phase. The shapes of our synthetic light-curves are consistent with existing observations of WASP-12b, but the required near-UV optical depth ($\\tau \\sim 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 ...

  5. The quasi deuteron model for low energy pion absorption

    International Nuclear Information System (INIS)

    In this thesis pion absorption in complex nuclei is studied in the quasi-deuteron model in which the pion is absorbed on a nucleon pair in the nucleus. The mechanism is studied in the low-energy domain since then the in-medium (pi→NN) operator turns out to be of simple character. In Ch. 2 and 3 this operator is constructed and analytical expressions are derived for (pi,NN) distributions in a plane wave impulse approximation for nuclei. The results turn out to be very useful for developing insight in the possibilities inherent in the QDM and the interpretation of the results in later chapters. Ch. 4 to 6 are devoted to the more realistic distorted wave calculations. In Ch. 4 the formal framework is presented and the calculational details are discussed. Ch.5 and 6 contain the comparison to stopped pion and in-flight data respectively. In Ch. 7 the main results are summarized. (Auth.)

  6. Evaluation and Modeling of the Digestion and Absorption of Novel Manufacturing Technology in Food Enterprises

    OpenAIRE

    Kerong Zhang; Wuyi Liu

    2015-01-01

    The food industry is more and more in need of importing and absorption new technologies. Focusing on all the possible issues of contradiction and difficulty to improve the digestion and absorption of novel manufacturing technology, a set of customized dynamic quantitative evaluation models were put forward that made it easy to model and supervise the usages, digestion and absorption of novel manufacturing technology in food enterprises. According to the proposed set of evaluation models, anyo...

  7. Measurements of the Absorption by Auditorium SEATING—A Model Study

    Science.gov (United States)

    BARRON, M.; COLEMAN, S.

    2001-01-01

    One of several problems with seat absorption is that only small numbers of seats can be tested in standard reverberation chambers. One method proposed for reverberation chamber measurements involves extrapolation when the absorption coefficient results are applied to actual auditoria. Model seat measurements in an effectively large model reverberation chamber have allowed the validity of this extrapolation to be checked. The alternative barrier method for reverberation chamber measurements was also tested and the two methods were compared. The effect on the absorption of row-row spacing as well as absorption by small numbers of seating rows was also investigated with model seats.

  8. A model for the spectral dependence of optically induced absorption in amorphous silicon

    Science.gov (United States)

    Lawandy, N. M.

    1990-01-01

    A model based on transitions from localized band tail states to states above the mobility edge is used to explain the broad band induced absorptions observed in recent pump-probe experiments. The model gives the observed decrease of absorption with frequency at subband gap photo energies and high carrier densities (of about 10 to the 20th/cu cm). At lower carrier densities, the absorption has a maximun which is sensitive to the spatial extent of the band tail states.

  9. Thermodynamic modeling of hydrogen sulfide absorption by aqueous N-methyldiethanolamine using the Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj

    2015-01-01

    system. The Extended UNIQUAC model is used to represent the system behavior. The model is created based on models for the constituent binary subsystems. The developed model provides accurate representation of VLE and heat of absorption for the studied system and subsystem in the temperature range of 0......Aqueous MDEA is the most commonly used solvent for H2S removal from natural gas. A reliable thermodynamic model is required for the proper design of natural gas sweetening processes. In this study, a rigorous thermodynamic model is developed to represent properties of the H2S-MDEA-H2O ternary...

  10. Wave scattering through classically chaotic cavities in the presence of absorption: A maximum-entropy model

    Indian Academy of Sciences (India)

    Pier A Mello; Eugene Kogan

    2002-02-01

    We present a maximum-entropy model for the transport of waves through a classically chaotic cavity in the presence of absorption. The entropy of the -matrix statistical distribution is maximized, with the constraint $\\langle {\\rm Tr}SS^{\\dagger}\\rangle = n: n$ is the dimensionality of , and 0 ≤ ≤ 1. For = 1 the -matrix distribution concentrates on the unitarity sphere and we have no absorption; for = 0 the distribution becomes a delta function at the origin and we have complete absorption. For strong absorption our result agrees with a number of analytical calculations already given in the literature. In that limit, the distribution of the individual (angular) transmission and reflection coefficients becomes exponential – Rayleigh statistics – even for = 1. For ≫ 1 Rayleigh statistics is attained even with no absorption; here we extend the study to < 1. The model is compared with random-matrix-theory numerical simulations: it describes the problem very well for strong absorption, but fails for moderate and weak absorptions. The success of the model for strong absorption is understood in the light of a central-limit theorem. For weak absorption, some important physical constraint is missing in the construction of the model.

  11. Particle-in-a-Box Model of Exciton Absorption and Electroabsorption in Conjugated Polymers

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm

    2001-01-01

    The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces...... a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed....

  12. Modeling of continuous absorption of electromagnetic radiation in dense partially ionized plasmas

    OpenAIRE

    Mihajlov, A. A.; Sakan, N. M.; Sreckovic, V. A.; Vitel, Y.

    2012-01-01

    A new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in dense partially ionized hydrogen plasma is tested in this work. It is shown that the obtained results give a possibility of calculating spectral absorption coefficients which characterize the relevant absorption processes in partially ionized hydrogen plasmas with electron densities $N_{e} \\sim 10^{19}cm^{-3}$ and temperatures $T \\approx 2\\cdot 10^{4}K$. A key parameter of the used procedure is det...

  13. Managing Creativity for Absorptive Capacity: The NIH Syndrome and the Implementation of Open Innovation Business Model

    DEFF Research Database (Denmark)

    Cokpekin, Özge

    The benefits of the open innovation business model and the absorptive capacity necessary to acquire and utilize external knowledge have been discussed extensively. An emerging literature stream has identified certain intra-organizational antecedents of absorptive capacity. However how firms...... recognize potentially valuable external knowledge to be able to start the knowledge absorption process has not been discussed. This paper suggests creativity management and argues that stimulating meaningfully novel behavior positively influences the recognition ability and the communication it enhances...

  14. Thermodynamic modeling of CO2 absorption in aqueous N-Methyldiethanolamine using Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj

    2015-01-01

    A Thermodynamic model that can predict the behavior of the gas sweetening process over the applicable conditions is of vital importance in industry. In this work, Extended UNIQUAC model parameters optimized for the CO2-MDEA-H2O system are presented. Different types of experimental data consisting...... of pure MDEA vapor pressure, vapor-liquid equilibrium (VLE) (total pressure and CO2 partial pressure), freezing point depression (SLE), excess enthalpy, heat capacity and heat of absorption were used to adjust model parameters. The model was then used to predict the NMR spectroscopic data. The developed...... model accurately represents thermodynamic and thermal properties of the studied systems. The model parameters are valid in the temperature range from -15 to 200 °C, MDEA mass% of 5-75 and CO2 partial pressure of 0-6161.5 kPa....

  15. Electron and proton absorption calculations for a graphite/epoxy composite model. [large space structures

    Science.gov (United States)

    Long, E. R., Jr.

    1979-01-01

    The Bethe-Bloch stopping power relations for inelastic collisions were used to determine the absorption of electron and proton energy in cured neat epoxy resin and the absorption of electron energy in a graphite/epoxy composite. Absorption of electron energy due to bremsstrahlung was determined. Electron energies from 0.2 to 4.0 MeV and proton energies from 0.3 to 1.75 MeV were used. Monoenergetic electron energy absorption profiles for models of pure graphite, cured neat epoxy resin, and graphite/epoxy composites are reported. A relation is determined for depth of uniform energy absorption in a composite as a function of fiber volume fraction and initial electron energy. Monoenergetic proton energy absorption profiles are reported for the neat resin model. A relation for total proton penetration in the epoxy resin as a function of initial proton energy is determined. Electron energy absorption in the composite due to bremsstrahlung is reported. Electron and proton energy absorption profiles in cured neat epoxy resin are reported for environments approximating geosynchronous earth orbit.

  16. Model of the in vivo spectral absorption of algal pigments. Part 1. Mathematical apparatus

    Directory of Open Access Journals (Sweden)

    Bogdan Wo¼niak

    2000-06-01

    Full Text Available Existing statistical models of in vivo light absorption by phytoplankton (Wozniak & Ostrowska 1990, Bricaud et al. 1995, 1998 describe the dependence of the phytoplankton specific spectral absorption coefficient a*pl(λ on the chlorophyll a concentration Ca in seawater. However, the models do not take into account the variability in this relationship due to phytoplankton acclimation. The observed variability in the light absorption coefficient and its components due to various pigments with depth and geographical position at sea, requires further accurate modelling in order to improve satellite remote sensing algorithms and interpretation of ocean colour maps.      The aim of this paper is to formulate an improved model of the phytoplankton spectral absorption capacity which takes account of the pigment composition and absorption changes resulting from photo- and chromatic acclimation processes, and the pigment package effect. It is a synthesis of earlier models and the following statistical generalisations: (1 statistical relationships between various pigment group concentrations and light field properties in the sea (described by Majchrowski & Ostrowska 2000, this volume; (2 a model of light absorption by phytoplankton capable of determining the mathematical relationships between the spectral absorption coefficients of the various photosynthetic and photoprotecting pigment groups, and their concentrations in seawater (Wozniak et al. 1999; (3 bio-optical models of light propagation in oceanic Case 1 Waters and Baltic Case 2 Waters (Wozniak et al. 1992a,b, 1995a,b. The generalised model described in this paper permits the total phytoplankton light absorption coefficient in vivo as well as its components related to the various photosynthetic and photoprotecting pigments to be determined using only the surface irradiance PAR(0+ surface chlorophyll concentration Ca(0 and depth z in the sea as input data.

  17. DOUBLE SHELL TANK (DST) HYDROXIDE DEPLETION MODEL FOR CARBON DIOXIDE ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    OGDEN DM; KIRCH NW

    2007-10-31

    This document generates a supernatant hydroxide ion depletion model based on mechanistic principles. The carbon dioxide absorption mechanistic model is developed in this report. The report also benchmarks the model against historical tank supernatant hydroxide data and vapor space carbon dioxide data. A comparison of the newly generated mechanistic model with previously applied empirical hydroxide depletion equations is also performed.

  18. Modelling of the X-ray broad absorption features in Narrow-Line Seyfert 1s

    CERN Document Server

    Porquet, D; Dumont, A M

    2000-01-01

    We investigate the origin of the broad absorption features detected near 1-1.4 keV in several Narrow Line Seyfert 1 galaxies, by modelling the absorbing medium with various physical parameters, using the ionization code PEGAS. The observed properties of the X-ray absorption features can be reproduced by taking into account the peculiar soft X-ray excess which is well fitted by a blackbody plus an underlying power law. We equally stress that the emission coming from the absorbing medium (related to the covering factor) has a strong influence on the resulting X-ray spectrum, in particular on the apparent position and depth of the absorption features. A non-solar iron abundance may be required to explain the observed deep absorption. We also investigate the influence of an additional collisional ionization process (hybrid case) on the predicted absorption features.

  19. Modelling of the X-ray broad absorption features in Narrow-Line Seyfert 1s

    Science.gov (United States)

    Porquet, Delphine; Mouchet, Martine; Dumont Anne-Marie

    2000-09-01

    We investigate the origin of the broad absorption features detected near 1-1.4 keV in several Narrow-Line Seyfert 1 galaxies, by modelling the absorbing medium with various physical parameters, using the ionization code PEGAS. The observed properties of the X-ray absorption features can be reproduced by taking into account the peculiar soft X-ray excess which is well fitted by a blackbody plus an underlying power law. We equally stress that the emission coming from the absorbing medium (related to the covering factor) has a strong influence on the resulting X-ray spectrum, in particular on the apparent position and depth of the absorption features. A non-solar iron abundance may be required to explain the observed deep absorption. We also investigate the influence of an additional collisional ionization process ("hybrid case") on the predicted absorption features.

  20. An Inverse Modeling Approach to Estimating Phytoplankton Pigment Concentrations from Phytoplankton Absorption Spectra

    Science.gov (United States)

    Moisan, John R.; Moisan, Tiffany A. H.; Linkswiler, Matthew A.

    2011-01-01

    Phytoplankton absorption spectra and High-Performance Liquid Chromatography (HPLC) pigment observations from the Eastern U.S. and global observations from NASA's SeaBASS archive are used in a linear inverse calculation to extract pigment-specific absorption spectra. Using these pigment-specific absorption spectra to reconstruct the phytoplankton absorption spectra results in high correlations at all visible wavelengths (r(sup 2) from 0.83 to 0.98), and linear regressions (slopes ranging from 0.8 to 1.1). Higher correlations (r(sup 2) from 0.75 to 1.00) are obtained in the visible portion of the spectra when the total phytoplankton absorption spectra are unpackaged by multiplying the entire spectra by a factor that sets the total absorption at 675 nm to that expected from absorption spectra reconstruction using measured pigment concentrations and laboratory-derived pigment-specific absorption spectra. The derived pigment-specific absorption spectra were further used with the total phytoplankton absorption spectra in a second linear inverse calculation to estimate the various phytoplankton HPLC pigments. A comparison between the estimated and measured pigment concentrations for the 18 pigment fields showed good correlations (r(sup 2) greater than 0.5) for 7 pigments and very good correlations (r(sup 2) greater than 0.7) for chlorophyll a and fucoxanthin. Higher correlations result when the analysis is carried out at more local geographic scales. The ability to estimate phytoplankton pigments using pigment-specific absorption spectra is critical for using hyperspectral inverse models to retrieve phytoplankton pigment concentrations and other Inherent Optical Properties (IOPs) from passive remote sensing observations.

  1. Simulation Model for Dynamic Operation of Double-Effect Absorption Chillers

    Directory of Open Access Journals (Sweden)

    Ahmed Mojahid Sid Ahmed Mohammed Salih

    2014-07-01

    Full Text Available The development in the field of refrigeration and air conditioning systems driven by absorption cycles acquired a considerable importance recently. For commercial absorption chillers, an essential challenge for creating chiller model certainly is the shortage of components technical specifications. These kinds of specifications are usually proprietary for chillers producers. In this paper, a double-effect parallel-flow-type steam absorption chiller model based on thermodynamic and energy equations is presented. The chiller studied is Lithium bromide-water with capacity of 1250 RT (Refrigeration Tons. The governing equations of the dynamic operation of the chiller are developed. From available design information, the values of the overall heat transfer coefficients multiplied by the surface area are computed. The dynamic operation of the absorption chiller is simulated to study the performance of the system. The model is able to provide essential details of the temperature, concentration, and flow rate at each state point in the chiller.

  2. A polar cap absorption model optimization based on the vertical ionograms analysis

    Science.gov (United States)

    Zaalov, N. Y.; Moskaleva, E. V.

    2016-11-01

    Space weather events significantly affect the high frequency (HF) radio wave propagation. The now-casting and forecasting of HF radio wave absorption is important for the HF communication industries. This paper assimilates vertical sounding data into an absorption model to improve its performance as a now-casting tool. The approach is a modification of the algorithm elaborated by Sauer and Wilkinson, which is based on the riometer data. The optimization is focused on accounting for short timescale variation of the absorption. It should be noted that the expression of the frequency dependence of absorption induced by the energetic particle precipitation employed in Sauer and Wilkinson model is based on the riometer data at frequencies of 20, 30, and 50 MHz. The approach suggested in this paper provides an opportunity for expanding the frequency dependence of the absorption for frequencies below 10 MHz. The simulation of the vertical ionograms in the polar cap region uses a computational model designed to overcome the high frequency wave propagation problem in high latitude of the Earth. HF radio wave absorption induced by solar UV illumination, X-ray flares and energetic particles precipitation is taken into consideration in our model. The absorption caused by the energetic particle precipitation is emphasized, because the study is focused on HF wave propagation in polar cap region. A comparison of observed and simulated vertical ionograms enables the coefficients, which relate absorption (day-time and night-time) to integral proton flux to be refined. The values of these coefficients determined from evaluation of the data recorded by any reliable ionosonde are valid for absorption calculation in high-latitude region.

  3. In silico modelling of mass transfer & absorption in the human gut

    OpenAIRE

    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. Fo...

  4. Consensus hologram QSAR modeling for the prediction of human intestinal absorption.

    Science.gov (United States)

    Moda, Tiago L; Andricopulo, Adriano D

    2012-04-15

    Consistent in silico models for ADME properties are useful tools in early drug discovery. Here, we report the hologram QSAR modeling of human intestinal absorption using a dataset of 638 compounds with experimental data associated. The final validated models are consistent and robust for the consensus prediction of this important pharmacokinetic property and are suitable for virtual screening applications. PMID:22425566

  5. Consensus hologram QSAR modeling for the prediction of human intestinal absorption.

    Science.gov (United States)

    Moda, Tiago L; Andricopulo, Adriano D

    2012-04-15

    Consistent in silico models for ADME properties are useful tools in early drug discovery. Here, we report the hologram QSAR modeling of human intestinal absorption using a dataset of 638 compounds with experimental data associated. The final validated models are consistent and robust for the consensus prediction of this important pharmacokinetic property and are suitable for virtual screening applications.

  6. Atomistic modeling of H absorption in Pd nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ruda, M., E-mail: ruda@cab.cnea.gov.a [Centro Atomico Bariloche, 8400 Bariloche (Argentina); Centro Regional Universitario Bariloche, U.N. Comahue (Argentina); Crespo, E.A., E-mail: crespo@uncoma.edu.a [Depto. de Fisica, Fac. de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquen (Argentina); Debiaggi, S. Ramos de, E-mail: ramos@uncoma.edu.a [Depto. de Fisica, Fac. de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquen (Argentina); CONICET (Argentina)

    2010-04-16

    Size affects the properties of absorption of H in Palladium nanoparticles. Because of their higher proportion of surface atoms compared to the bulk, the pressure-composition (P-C) isotherms of the nanoparticles are modified. We performed atomistic simulations for different-sized Pd nanoparticles and for the bulk at different H concentrations using the Monte Carlo technique in the TP{mu}N ensemble to calculate the P-C isotherms. The Pd-H interatomic potentials are of the Embedded Atom (EAM) type and have been recently developed by Zhou et al. . From the related van't Hoff equation we obtained |{Delta}H{sup o}| = (28 {+-} 7) kJ/0.5 mol of H{sub 2} and |{Delta}S{sup o}| = (71 {+-} 19) J/0.5 mol of H{sub 2}.K for the PdH formation in the bulk. For Pd nanoparticles previous simulations results based on a different set of EAM potentials showed that H was absorbed primarily in the surface before diffusing into the inside of small Pd clusters . Considering the better performance of Zhou's potentials for the bulk, in this work we analyzed the evolution of the equilibrium microstructure of Pd nanoparticles as a function of their size and H concentration. Our simulations predict enhanced hydrogen solubilities and vanishing plateaux when compared to the bulk and that H is absorbed in the subsurface of the nanoparticles.

  7. Modelling and data validation for the energy analysis of absorption refrigeration systems

    OpenAIRE

    Martínez Maradiaga, David Estéfano

    2013-01-01

    Data validation and reconciliation techniques have been extensively used in the process industry to improve the data accuracy. These techniques exploit the redundancy in the measurements in order to obtain a set of adjusted measurements that satisfy the plant model. Nevertheless, not many applications deal with closed cycles with complex connectivity and recycle loops, as in absorption refrigeration cycles. This thesis proposes a methodology for the steady-state data validation of absorption ...

  8. Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

    Science.gov (United States)

    Alvarado, Matthew J.; Lonsdale, Chantelle R.; Macintyre, Helen L.; Bian, Huisheng; Chin, Mian; Ridley, David A.; Heald, Colette L.; Thornhill, Kenneth L.; Anderson, Bruce E.; Cubison, Michael J.; Jimenez, Jose L.; Kondo, Yutaka; Sahu, Lokesh K.; Dibb, Jack E.; Wang, Chien

    2016-07-01

    Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10-23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction

  9. A model for absorption of solar radiation by mineral dust within liquid cloud drops

    Science.gov (United States)

    Zhang, Qing; Thompson, Jonathan E.

    2015-10-01

    Models of light scattering and absorption that consider the effect of insoluble inclusions present within liquid cloud droplets may assume the inclusion occupies random locations within the droplet. In certain cases, external forces can lead to certain orientations or alignments that are strongly preferred. Within this modeling study, we consider one such case in which an insoluble mineral dust inclusion (ρ=2.6 g/cm3) is placed within a liquid water drop (ρ=1.0 g/cm3). Such an instance mimics mineral dust aerosols being incorporated within cloud drops in Earth's atmosphere. Model results suggest super-micron mineral dust settles to the bottom of cloud droplets. However, Brownian motion largely randomizes the position of sub-micron mineral dust within the droplet. The inherent organization of the particles that result has important consequences for light absorption by mineral dust when present within a cloud drop. Modeled results suggest light absorption efficiency may be enhanced by as much as 4-6 fold for an isolated droplet experiencing direct solar illumination at solar zenith angles of diffuse rather than direct solar irradiation. In such cases, light absorption efficiency is decreased through including super-micron dust within water droplets. The study has important implications for modeling the absorption of sunlight by mineral dust aerosol within liquid water clouds. The angle of incidence dependence also reveals that experimental measurement of light absorption for cases in which particle alignment occurs may not always accurately reflect atmospheric absorption of sunlight. Therefore, care must be taken to extrapolate measurement data to climate models.

  10. A mathematical model of peritoneal fluid absorption in tissue.

    Science.gov (United States)

    Stachowska-Pietka, Joanna; Waniewski, Jacek; Flessner, Michael F; Lindholm, Bengt

    2005-01-01

    To investigate how water flow and interstitial pressure change in tissue during a peritoneal dwell with isotonic fluid, we developed a mathematical model of water transport in the tissue. Transport through muscle alone (M) and through muscle with intact skin (MS) were considered for the rat abdominal wall, using various parameters for muscle and skin. Based on the concept of distributed capillary and lymphatic systems, two main transport barriers were taken into account. capillary membrane and interstitium. We calculated the tissue hydrostatic pressure profiles and compared them with experimental data. The theoretic steady-state pressure distribution for model M is in good agreement with the experimental data. In model MS, the theoretic distribution diverges from the data in the subcutaneous layer. The transient times for fluid flow in the tissue for both model simulations are rather long (40 minutes in model M and 95 minutes in model MS) and depend on intraperitoneal pressure. The fraction of fluid absorbed from the tissue by the lymphatics increases with time from 10% to 97% of fluid flow from the peritoneal cavity. PMID:16686276

  11. Experimental measurement and modeling of the rate of absorption of carbon dioxide by aqueous ammonia

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J.M.; Fosbøl, Philip Loldrup;

    2011-01-01

    In this work, the rate of absorption of carbon dioxide by aqueous ammonia solvent has been studied by applying a newly built wetted wall column. The absorption rate in aqueous ammonia was measured at temperatures from 279 to 304K for 1 to 10wt% aqueous ammonia with loadings varying from 0 to 0.8mol......CO2/molNH3. The absorption rate in 30wt% aqueous mono-ethanolamine (MEA) was measured at 294 and 314K with loadings varying from 0 to 0.4 as comparison.It was found that at 304K, the rate of absorption of carbon dioxide by 10wt% NH3 solvent was comparable to the rates for 30wt% MEA at 294 and 314K (a.......The rate of absorption decreases strongly with decreasing ammonia concentrations and increasing CO2 loadings.The rate of absorption of carbon dioxide by aqueous ammonia solvent was modeled using the measurements of the unloaded solutions and the zwitter-ion mechanism. The model could successfully predict...

  12. Modelling of the Absorption and Desorption Process of Chemical Heat Pumps

    Institute of Scientific and Technical Information of China (English)

    Gui-PingLin; Xiu-GanYuan

    1993-01-01

    A simple model for the desorption and absorption process of the chemical heat pump is presented in this paper .It is based on the assumption of a definite reaction front.The results from this model are compared with those obtained by finite difference method and it is observed that there is almost no difference between them.

  13. Enhancement Factors in Ozone Absorption Based on the Surface Renewal Model and its Application

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the Danckwerts surface renewal model, a simple explicit expression of theenhancement factor in ozone absorption with a first order ozone self-decomposition and parallel secondorder ozonation reactions has been derived. The results are compared with our previous work based onthe film theory. The 2,4-dichlorophenol destruction rate by ozonation is predicted using the enhancementfactor model in this paper.

  14. Comparison of a Reaction Front Model and a Finite Difference Model for the Simulation of Solid Absorption Process

    Institute of Scientific and Technical Information of China (English)

    ZikangWu; ArneJakobsen; 等

    1994-01-01

    The pupose of this paper is to investigate the validity of a lumped model,i.e.a reaction front model,for the simulation of solid absorption process.A distributed model is developed for solid absorption process,and a dimensionless RF number is suggested to predict the qualitative shape of reaction degree profile.The simulation results from the reaction front model are compared with those from the distributed model solved by a finite difference scheme,and it is shown that they are in good agreement in almost all cased.no matter whether there is reaction front or not.

  15. Sulfur K-edge X-ray absorption spectroscopy of petroleum asphaltenes and model compounds

    International Nuclear Information System (INIS)

    The utility of sulfur K-edge X-ray absorption spectroscopy for the determination and quantification of sulfur forms in petroleum asphaltenes has been investigated. Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra were obtained for a selected group of model compounds and for several petroleum asphaltene samples. For the model compounds the sulfur XANES was found to vary widely from compound to compound and to provide a fingerprint for the form of sulfur involved. The use of third derivatives of the spectra enabled discrimination of mixtures of sulfidic and thiophenic model compounds and allowed approximate quantification of the amount of each component in the mixtures and in the asphaltene samples. These results represent the first demonstration that nonvolatile sulfur forms can be distinguished and approximately quantified by direct measurement

  16. Semimechanistic model describing gastric emptying and glucose absorption in healthy subjects and patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Alskär, Oskar; Bagger, Jonatan I; Røge, Rikke M;

    2015-01-01

    of small intestinal transit time, glucose inhibition of gastric emptying, and saturable absorption of glucose over the epithelium to improve the description of gastric emptying and glucose absorption in the IGI model. Duodenal glucose was found to inhibit gastric emptying. The performance of the saturable......The integrated glucose-insulin (IGI) model is a previously published semimechanistic model that describes plasma glucose and insulin concentrations after glucose challenges. The aim of this work was to use knowledge of physiology to improve the IGI model's description of glucose absorption...... glucose absorption was superior to linear absorption regardless of the gastric emptying model applied. The semiphysiological model developed performed better than previously published empirical models and allows better understanding of the mechanisms underlying glucose absorption. In conclusion, our new...

  17. Photon absorption models in nanostructured semiconductor solar cells and devices

    CERN Document Server

    Luque, Antonio

    2015-01-01

    This book is intended to be used by materials and device physicists and also solar cells researchers. It models the performance characteristics of nanostructured solar cells and resolves the dynamics of transitions between several levels of these devices. An outstanding insight into the physical behaviour of these devices is provided, which complements experimental work. This therefore allows a better understanding of the results, enabling the development of new experiments and optimization of new devices. It is intended to be accessible to researchers, but also to provide engineering tools w

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

    OpenAIRE

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

    2010-01-01

    Date pits for feed preparation or oil extraction are soaked in water to soften before milling or extrusion. Knowledge of water absorption by the date pits helps in better managing the soaking duration. In this research, the process of water absorption by date pits was modeled and analyzed using Fick’s second law of diffusion, finite element approach, and Peleg model. The moisture content of the pits reached to its saturation level of 41.5% (wet basis) after 10 d. The estimated coefficient of ...

  19. Modeling the thermal absorption factor of photovoltaic/thermal combi-panels

    International Nuclear Information System (INIS)

    In a photovoltaic/thermal combi-panel solar cells generate electricity while residual heat is extracted to be used for tap water heating or room heating. In such a panel the entire solar spectrum can be used in principle. Unfortunately long wavelength solar irradiance is poorly absorbed by the semiconductor material in standard solar cells. A computer model was developed to determine the thermal absorption factor of crystalline silicon solar cells. It was found that for a standard untextured solar cell with a silver back contact a relatively large amount of long wavelength irradiance is lost by reflection resulting in an absorption factor of only 74%. The model was then used to investigate ways to increase this absorption factor. One way is absorbing long wavelength irradiance in a second absorber behind a semi-transparent solar cell. According to the model this will increase the total absorption factor to 87%. The second way is to absorb irradiance in the back contact of the solar cell by using rough interfaces in combination with a non-standard metal as back contact. Theoretically the absorption factor can then be increased to 85%

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

    Science.gov (United States)

    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.

  1. Models of Five Absorption Line Systems Along the Line of Sight Toward PG0117+213

    CERN Document Server

    Masiero, J R; Ding, J; Churchill, C W; Kacprzak, G G

    2005-01-01

    We present our investigation into the physical conditions of the gas in five intervening quasar absorption line systems along the line of sight toward the quasar PG 0117+213, with redshifts of z=0.57, z=0.72, z=1.04, z=1.32 and z=1.34. Photoionization modeling of HST, Keck I, and Palomar data, using the code Cloudy, is employed to derive densities and metallicities of the multiple phases of gas required to fit the absorption profile for each system. We discuss the implications of these models for galaxy evolution, including the interpretation of ``CIV deficiency'' and damped Lyman alpha absorbers (DLAs), and the relationships between galaxy morphology, galaxy luminosity, and absorption signature.

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

    Science.gov (United States)

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

    2010-07-01

    Date pits for feed preparation or oil extraction are soaked in water to soften before milling or extrusion. Knowledge of water absorption by the date pits helps in better managing the soaking duration. In this research, the process of water absorption by date pits was modeled and analyzed using Fick's second law of diffusion, finite element approach, and Peleg model. The moisture content of the pits reached to its saturation level of 41.5% (wet basis) after 10 d. The estimated coefficient of diffusion was 9.89x10(-12) m(2)/s. The finite element model with a proposed ellipsoid geometry for a single date pit and the analytical model fitted better to the experimental data with R(2) of 0.98. The former model slightly overestimated the moisture content of the pits during the initial stages of the soaking and the latter model generally underestimated this variable through the entire stages of soaking process. PMID:20593512

  3. Phenolic Acids from Wheat Show Different Absorption Profiles in Plasma: A Model Experiment with Catheterized Pigs

    DEFF Research Database (Denmark)

    Nørskov, Natalja; Hedemann, Mette Skou; Theil, Peter Kappel;

    2013-01-01

    The concentration and absorption of the nine phenolic acids of wheat were measured in a model experiment with catheterized pigs fed whole grain wheat and wheat aleurone diets. Six pigs in a repeated crossover design were fitted with catheters in the portal vein and mesenteric artery to study the ...

  4. Two- and three-dimensional models for analysis of optical absorption in tungsten disulphide single crystals

    Indian Academy of Sciences (India)

    Dhairya A Dholakia; G K Solanki; S G Patel; M K Agarwal

    2001-06-01

    The optical energy gaps of WS2 single crystal were determined from the analysis of the absorption spectrum near the fundamental absorption edge at room temperature using light parallel to -axis incident normally on the basal plane. On the basis of two- and three-dimensional models it was found that both direct and indirect band transitions took place in WS2 and the indirect transition was of the allowed type. The optical energy gaps corresponding to both transitions were determined and the phonon energies associated with the indirect transitions estimated. The implications of the results have been discussed.

  5. Modeling of continuous absorption of electromagnetic radiation in dense partially ionized plasmas

    CERN Document Server

    Mihajlov, A A; Sreckovic, V A; Vitel, Y; 10.1088/1751-8113/44/9/095502

    2012-01-01

    A new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in dense partially ionized hydrogen plasma is tested in this work. It is shown that the obtained results give a possibility of calculating spectral absorption coefficients which characterize the relevant absorption processes in partially ionized hydrogen plasmas with electron densities $N_{e} \\sim 10^{19}cm^{-3}$ and temperatures $T \\approx 2\\cdot 10^{4}K$. A key parameter of the used procedure is determined empirically. The calculation method is applied to wavelength region $300nm < \\lambda < 500nm$. The presented results can be of interest for dense laboratory plasmas as well as for partially ionized layers of different stellar atmospheres.

  6. Modeling of continuous absorption of electromagnetic radiation in dense partially ionized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mihajlov, A A; Sakan, N M; Sreckovic, V A [Institute of Physics, Belgrade University, Pregrevica 118, Zemun, 11080 Belgrade (Serbia); Vitel, Y, E-mail: mihajlov@ipb.ac.rs [UPMC Univ Paris 6, Laboratoire des Plasmas Denses, 3 rue Galilee, 94200 Ivry sur Seine (France)

    2011-03-04

    A new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in a dense partially ionized hydrogen plasma is tested in this work. It is shown that the obtained results give a possibility of calculating spectral absorption coefficients which characterize the relevant absorption processes in partially ionized hydrogen plasmas with electron densities N{sub e} {approx} 10{sup 19} cm{sup -3} and temperatures T {approx} 2 x 10{sup 4} K. A key parameter of the used procedure is determined empirically. The calculation method is applied to the wavelength region 300 nm < {lambda} < 500 nm. The presented results can be of interest for dense laboratory plasmas as well as for partially ionized layers of different stellar atmospheres.

  7. A new analysis of fine-structure constant measurements and modelling errors from quasar absorption lines

    Science.gov (United States)

    Wilczynska, Michael R.; Webb, John K.; King, Julian A.; Murphy, Michael T.; Bainbridge, Matthew B.; Flambaum, Victor V.

    2015-12-01

    We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of 0.4 ≤ zabs ≤ 2.3 observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Considering both statistical and systematic error contributions we find a robust estimate of the weighted mean deviation of the fine-structure constant from its current, laboratory value of Δα/α = (0.22 ± 0.23) × 10-5, consistent with the dipole variation reported in Webb et al. and King et al. This paper also examines modelling methodologies and systematic effects. In particular, we focus on the consequences of fitting quasar absorption systems with too few absorbing components and of selectively fitting only the stronger components in an absorption complex. We show that using insufficient continuum regions around an absorption complex causes a significant increase in the scatter of a sample of Δα/α measurements, thus unnecessarily reducing the overall precision. We further show that fitting absorption systems with too few velocity components also results in a significant increase in the scatter of Δα/α measurements, and in addition causes Δα/α error estimates to be systematically underestimated. These results thus identify some of the potential pitfalls in analysis techniques and provide a guide for future analyses.

  8. Application of Absorption Modeling in Rational Design of Drug Product Under Quality-by-Design Paradigm.

    Science.gov (United States)

    Kesisoglou, Filippos; Mitra, Amitava

    2015-09-01

    Physiologically based absorption models can be an important tool in understanding product performance and hence implementation of Quality by Design (QbD) in drug product development. In this report, we show several case studies to demonstrate the potential application of absorption modeling in rational design of drug product under the QbD paradigm. The examples include application of absorption modeling—(1) prior to first-in-human studies to guide development of a formulation with minimal sensitivity to higher gastric pH and hence reduced interaction when co-administered with PPIs and/or H2RAs, (2) design of a controlled release formulation with optimal release rate to meet trough plasma concentrations and enable QD dosing, (3) understanding the impact of API particle size distribution on tablet bioavailability and guide formulation design in late-stage development, (4) assess impact of API phase change on product performance to guide specification setting, and (5) investigate the effect of dissolution rate changes on formulation bioperformance and enable appropriate specification setting. These case studies are meant to highlight the utility of physiologically based absorption modeling in gaining a thorough understanding of the product performance and the critical factors impacting performance to drive design of a robust drug product that would deliver the optimal benefit to the patients.

  9. Modeling of the Temperature Effect on Oxygen Absorption by Iron-Based Oxygen Scavengers.

    Science.gov (United States)

    Polyakov, Vladimir A; Miltz, Joseph

    2016-01-01

    A new engineering-oriented model for prediction of the effect of temperature on the kinetics of oxygen absorption by iron-based oxygen scavengers (IOSs) was developed. The model is based on the physicochemical mechanism of the O2 scavenging process by the active component of the IOS (iron powder). The conclusions of this study are: (1) the iron deposits formed on the iron particles are composed of 2 different layers: an inner layer of Fe3 O4 and an outer layer of FeOOH that vanishes with the depletion of oxygen. (2) The model considers the chemical processes in the heterogeneous closed system "Fe-H2 O-NaCl-O2 " and describes the kinetics of oxygen absorption by the powder, depending on the characteristics of the system. (3) The nonlinear ordinary differential equation (ODE) of the O2 absorption kinetics was derived and a simple approximate solution to this ODE was obtained theoretically that is similar to the empirical exponential formula published in the relevant literature. (4) The temperature dependence of the oxygen absorption rate is more complicated than that described by the Arrhenius equation. PMID:26650762

  10. Percutaneous absorption of an insect repellent p-menthane-3,8-DIOL: a model for human dermal absorption.

    Science.gov (United States)

    Reifenrath, William G; Olson, James J; Vedula, Usha; Osimitz, Thomas G

    2009-01-01

    p-Menthane-3,8-diol(38DIOL) was recently introduced as a natural topical insect repellent in the commercial product "OFF! Botanicals" lotion. The objective of this study was to provide an estimate of the potential for 38DIOL systemic absorption in humans. Carbon-14-labeled 38DIOL formulated in the lotion and in an ethanol solution was applied to excised pig skin in an in vitro flow-through test system predictive of skin absorption in humans. Twenty-four hours after application, radiolabel recovered from the dermis and receptor fluid was summed to determine percent absorption. At a dose of approximately 80 microg/cm(2) of 38DIOL in the lotion, a value of 3.5 +/- 0.8% of applied dose was obtained with pig skin. The corresponding value for 38DIOL in ethanol (90 microg/cm(2)) was not significantly different (3.0 +/- 1.2%). Most of the applied dose of 38DIOL was found to evaporate from pig skin (77 +/- 8% for the lotion and 87 +/- 1% for ethanol solution), thus limiting percutaneous absorption values. For reference purposes, the pig skin absorptions of piperonyl butoxide (PBO) at 100 microg/cm(2) in isopropanol, N,N-diethyl-m-toluamide (DEET) at 500 microg/cm(2) in ethanol, and neat isododecane at 650 microg/cm(2) (in order of increasing volatility) were 15 +/- 6%, 23 +/- 3%, and 0.09 +/- 0.05% of applied dose respectively. Isododecane was lost almost exclusively from the skin surface by evaporation. For additional reference, absorptions of PBO, DEET, and 38DIOL were found to be higher with excised rat skin. PMID:19557607

  11. Microwave Absorption and Response Modeling of Nanocomposites Embedded SiC Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    LU Ran; FANG Xiao-Yong; KANG Yu-Qing; YUAN Jie; CAO Mao-Sheng

    2009-01-01

    @@ We study the mechanism of microwave response properties of SiCp/paraffin nanocomposites and propose a mi-crowave absorption model of nanocomposites based on the conservation law of energy and the theory of electro-magnetic scattering. Using the model we calculate the reflectivity of SiCp/paraffin nanocomposites ranging from 2 CHz to 18 GHz. The calculated results are very consistent with the experimental data in the frequency range investigated.

  12. Mathematical Model of Fiber Optic Temperature Sensor Based on Optic Absorption and Experiment Testing

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    On the basis of analysis on the temperature monitoring methods for high voltage devices, a new type of fiber optic sensor structure with reference channel is given. And the operation principle of fiber optic sensor is analysed at large based on the absorption of semiconductor chip. The mathematical model of both devices and the whole system are also given. It is proved by the experiment that this mathematical model is reliable.

  13. A Model For The Absorption Of Thermal Radiation By Gold-Black

    OpenAIRE

    Quinlan, Brendan Robert

    2015-01-01

    The work presented here addresses an important topic in thermal radiation detection when gold-black is used as an absorber. Sought is a model to simulate the absorption of thermal radiation by gold-black. Fractal geometry is created to simulate the topology of gold-black. Then electrical circuits based on the topology are identified that capture the physics of the interaction between the gold-black material and incident electro-magnetic radiation. Parameters of the model are then adj...

  14. Enhancement Factors in Ozone Absorption Based on the Surface Renewal Model and its Application

    Institute of Scientific and Technical Information of China (English)

    程江; 杨卓如; 陈焕钦; C.H.Kuo; M.E.Zappi

    2000-01-01

    Based on the Danckwerts surface renewal model, a simple explicit expression of the enhancement factor in ozone absorption with a first order ozone self-decomposition and parallel second order ozonation reactions has been derived. The results are compared with our previous work based on the film theory. The 2,4-dichlorophenol destruction rate by ozonation is predicted using the enhancement factor model in this paper.

  15. Dynamic modelling of CO2 absorption for post combustion capture in coal-fired power plants

    OpenAIRE

    Lawal, Adekola; Wang, Meihong; Stephenson, Peter; Yeung, Hoi

    2009-01-01

    Power generation from fossil fuel-fired power plants is the largest single source of CO2 emissions. Post combustion capture via chemical absorption is viewed as the most mature CO2 capture technique. This paper presents a study of the post combustion CO2 capture with monoethanolamine (MEA) based on dynamic modelling of the process. The aims of the project were to compare two different approaches (the equilibrium-based approach versus the rate-based approach) in modelling the...

  16. Multiscale modeling of light absorption in tissues: limitations of classical homogenization approach.

    Science.gov (United States)

    Mottin, Stephane; Panasenko, Grigory; Ganesh, S Sivaji

    2010-12-31

    In biophotonics, the light absorption in a tissue is usually modeled by the Helmholtz equation with two constant parameters, the scattering coefficient and the absorption coefficient. This classic approximation of "haemoglobin diluted everywhere" (constant absorption coefficient) corresponds to the classical homogenization approach. The paper discusses the limitations of this approach. The scattering coefficient is supposed to be constant (equal to one) while the absorption coefficient is equal to zero everywhere except for a periodic set of thin parallel strips simulating the blood vessels, where it is a large parameter ω. The problem contains two other parameters which are small: ε, the ratio of the distance between the axes of vessels to the characteristic macroscopic size, and δ, the ratio of the thickness of thin vessels and the period. We construct asymptotic expansion in two cases: ε --> 0, ω --> ∞, δ --> 0, ωδ --> ∞, ε2ωδ --> 0 and ε --> 0, ω --> ∞, δ --> 0, ε2ωδ --> ∞, and and prove that in the first case the classical homogenization (averaging) of the differential equation is true while in the second case it is wrong. This result may be applied in the biomedical optics, for instance, in the modeling of the skin and cosmetics.

  17. A model for absorption determination of radioactive materials: application in the radio dosimetry and nutrition study

    International Nuclear Information System (INIS)

    A three-parameter model of the sigmoidal relationship is proposed to explain the food passage by intestinal tube. These parameters are: U = intestinal non-absorbed radioactivity; d parameter related to intestinal food dispersion; and t50 = time to maximal appearance of material from the intestinal lumen. In order to illustrate the applications of this model and its validity, the absorption of 65Zn from casein semi-purified diet was evaluated in rats. There was a good agreement between the predicted values and the experimental data when the sigmoidal component was added to the conventional multicompartimental equations. With this kind of model the time to maximal appearance (hours), the true absorption level, the fecal concentration and the intestinal dispersion of the ingested radioactivity material may be determined. (author)

  18. An analytical solution for the model of drug distribution and absorption in small intestine

    Science.gov (United States)

    Mingyu, Xu

    1990-11-01

    According to the physiological and anatomical characteristics of small intestine, neglecting the effect of its motility on the distribution and absorption of drug and nutrient, Y. Miyamoto et al.[1] proposed a model of two-dimensional laminar flow in a circular porous tube with permeable wall and calculated the concentration profile of drug by numerical analysis. In this paper, we give a steady state analytical solution of the above model including deactivation term. The obtained results are in agreement with the results of their numerical analysis. Moreover the analytical solution presented in this paper reveals the relation among the physiological parameters of the model and describes the basic absorption rule of drug and nutrient through the intestinal wall and hence provides a theoretical basis for determining the permeability and reflection coefficient through in situ experiments.

  19. Experimental validation of a model for diffusion-controlled absorption of organic compounds in the trachea

    Energy Technology Data Exchange (ETDEWEB)

    Gerde, P. [National Inst. for Working Life, Solna (Sweden); Muggenburg, B.A.; Thornton-Manning, J.R. [and others

    1995-12-01

    Most chemically induced lung cancer originates in the epithelial cells in the airways. Common conceptions are that chemicals deposited on the airway surface are rapidly absorbed through mucous membranes, limited primarily by the rate of blood perfusion in the mucosa. It is also commonly thought that for chemicals to induce toxicity at the site of entry, they must be either rapidly reactive, readily metabolizable, or especially toxic to the tissues at the site of entry. For highly lipophilic toxicants, there is a third option. Our mathematical model predicts that as lipophilicity increases, chemicals partition more readily into the cellular lipid membranes and diffuse more slowly through the tissues. Therefore, absorption of very lipophilic compounds will be almost entirely limited by the rate of diffusion through the epithelium rather than by perfusion of the capillary bed in the subepithelium. We have reported on a preliminary model for absorption through mucous membranes of any substance with a lipid/aqueous partition coefficient larger than one. The purpose of this work was to experimentally validate the model in Beagle dogs. This validated model on toxicant absorption in the airway mucosa will improve risk assessment of inhaled

  20. The potential of chitosan in enhancing peptide and protein absorption across the TR146 cell culture model-an in vitro model of the buccal epithelium

    DEFF Research Database (Denmark)

    Portero, Ana; Remuñán-López, Carmen; Nielsen, Hanne Mørck

    2002-01-01

    To investigate the potential of chitosan (CS) to enhance buccal peptide and protein absorption, the TR146 cell culture model, a model of the buccal epithelium, was used.......To investigate the potential of chitosan (CS) to enhance buccal peptide and protein absorption, the TR146 cell culture model, a model of the buccal epithelium, was used....

  1. Instantaneous Shape Sampling - a model for the $\\gamma$-absorption cross section of transitional nuclei

    CERN Document Server

    Bentley, I; Doenau, F; Frauendorf, S; Kampfer, B; Schwengner, R; Zhang, S

    2010-01-01

    The influence of the quadrupole shape fluctuations on the dipole vibrations in transitional nuclei is investigated in the framework of the Instantaneous Shape Sampling Model, which combines the Interacting Boson Model for the slow collective quadrupole motion with the Random Phase Approximation for the rapid dipole vibrations. Coupling to the complex background configurations is taken into account by folding the results with a Lorentzian with an energy dependent width. The low-energy energy portion of the $\\gamma$- absorption cross section, which is important for photo-nuclear processes, is studied for the isotopic series of Kr, Xe, Ba, and Sm. The experimental cross sections are well reproduced. The low-energy cross section is determined by the Landau fragmentation of the dipole strength and its redistribution caused by the shape fluctuations. Collisional damping only wipes out fluctuations of the absorption cross section, generating the smooth energy dependence observed in experiment. In the case of semi-ma...

  2. A Simple Model for the Absorption of Starlight by Dust in Galaxies

    CERN Document Server

    Charlot, S

    2000-01-01

    We present a new model to compute the effects of dust on the integratedspectral properties of galaxies, based on an idealized prescription of the mainfeatures of the interstellar medium (ISM). The model includes the ionization ofHII regions in the interiors of the dense clouds in which stars form and theinfluence of the finite lifetime of these clouds on the absorption ofradiation. We compute the production of emission lines and the absorption ofcontinuum radiation in the HII regions and the subsequent transfer of line andcontinuum radiation in the surrounding HI regions and the ambient ISM. Thisenables us to interpret simultaneously all the observations of a homogeneoussample of nearby UV-selected starburst galaxies, including the ratio of far-IRto UV luminosities, the ratio of Halpha to Hbeta luminosities, the Halphaequivalent width, and the UV spectral slope. We show that the finite lifetimeof stellar birth clouds is a key ingredient to resolve an apparent discrepancybetween the attenuation of line and con...

  3. A new analysis of fine-structure constant measurements and modelling errors from quasar absorption lines

    CERN Document Server

    Wilczynska, Michael R; King, Julian A; Murphy, Michael T; Bainbridge, Matthew B; Flambaum, Victor V

    2015-01-01

    We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of $0.4 \\leq z_{abs} \\leq 2.3$ observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Considering both statistical and systematic error contributions we find a robust estimate of the weighted mean deviation of the fine-structure constant from its current, laboratory value of $\\Delta\\alpha/\\alpha=\\left(0.22\\pm0.23\\right)\\times10^{-5}$, consistent with the dipole variation reported in Webb et al. and King et al. This paper also examines modelling methodologies and systematic effects. In particular we focus on the consequences of fitting quasar absorption systems with too few absorbing components and of selectively fitting only the stronger components in an absorption complex. We show that using insufficient continuum regions around an absorption complex causes a significant increase in the scatter of a sample of $\\Delta\\alpha/\\alpha$ measurements, th...

  4. The influence of surface effects on the hydrogen absorption investigated on the V H model system

    Science.gov (United States)

    Müller, K.-H.; Paulus, H.; Kiss, G.

    2001-07-01

    The system V-O-H has been chosen as a model system to investigate surface effects on hydrogen absorption in metals. By means of XPS, SIMS, and thermal desorption mass spectrometry (TDMS) methods, the influence of oxygen segregated from the bulk as well as adsorbed from the gas phase has been pointed out. Segregated oxygen obstructs the hydrogen absorption, whereas non-stoichiometric and stoichiometric oxides have a preventing effect already with coverages in the range of monolayers. Ion bombardment in connection with sputter-cleaning or SNMS and SIMS analyses produces additional absorption sites in the surface near region for hydrogen. These can be populated by hydrogen from the gas phase during H 2 exposure or diffusing from the bulk, if the sample was H 2 loaded before. Beside elements like vanadium, there exist alloys (e.g. TiFe, LaNi 5, TiMn 2), which are particularly suitable for practical storage purposes. It is important for the further development of such alloys but also for a better understanding of absorption kinetics to investigate the influence of surface effects also on these alloys.

  5. Application of Absorption Modeling to Predict Bioequivalence Outcome of Two Batches of Etoricoxib Tablets

    OpenAIRE

    Mitra, Amitava; Kesisoglou, Filippos; Dogterom, Peter

    2014-01-01

    As part of the overall product development and manufacturing strategy, pharmaceutical companies routinely change formulation and manufacturing site. Depending on the type and level of change and the BCS class of the molecule, dissolution data and/or bioequivalence (BE) may be needed to support the change for immediate release dosage forms. In this report, we demonstrate that for certain weakly basic low-solubility molecules which rapidly dissolve in the stomach, absorption modeling could be u...

  6. Dynamic Model and Performance of Absorption Heat Pump in Shut-down Process

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; LU Zhen

    2002-01-01

    The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure generator and heat exchanger are analyzed in detail. The proper shut-down mode of the heat pump is presented,which, in consideration of solution parameters, has a great effect on the possibility of crystallization of some components.

  7. Time-dependent excitation and ionization modelling of absorption-line variability due to GRB080310

    DEFF Research Database (Denmark)

    Vreeswijk, P.M.; De Cia, A.; Jakobsson, P.;

    2013-01-01

    We model the time-variable absorption of Feii, Feiii, Siii, Cii and Crii detected in Ultraviolet and Visual Echelle Spectrograph (UVES) spectra of gamma-ray burst (GRB) 080310, with the afterglow radiation exciting and ionizing the interstellar medium in the host galaxy at a redshift of z = 2.427...... ionized by the radiation released during the first few tens of minutes after the GRB. © 2012 ESO....

  8. Microscopic modeling of País grape seed extract absorption in the small intestine.

    Science.gov (United States)

    Morales, Cristian; Roeckel, Marlene; Fernández, Katherina

    2014-02-01

    The concentration profiles and the absorbed fraction (F) of the País grape seed extract in the human small intestine were obtained using a microscopic model simulation that accounts for the extracts' dissolution and absorption. To apply this model, the physical and chemical parameters of the grape seed extract solubility (C s), density (ρ), global mass transfer coefficient between the intestinal and blood content (k) (effective permeability), and diffusion coefficient (D) were experimentally evaluated. The diffusion coefficient (D = 3.45 × 10(-6) ± 5 × 10(-8) cm(2)/s) was approximately on the same order of magnitude as the coefficients of the relevant constituents. These results were chemically validated to discover that only the compounds with low molecular weights diffused across the membrane (mainly the (+)-catechin and (-)-epicatechin compounds). The model demonstrated that for the País grape seed extract, the dissolution process would proceed at a faster rate than the convective process. In addition, the absorbed fraction was elevated (F = 85.3%). The global mass transfer coefficient (k = 1.53 × 10(-4) ± 5 × 10(-6) cm/s) was a critical parameter in the absorption process, and minor changes drastically modified the prediction of the extract absorption. The simulation and experimental results show that the grape seed extract possesses the qualities of a potential phytodrug.

  9. Oral absorption of ginsenoside Rb1 using in vitro and in vivo models.

    Science.gov (United States)

    Han, Min; Sha, Xianyi; Wu, Yunjuan; Fang, Xiaoling

    2006-04-01

    This research attempts to clarify the cause for poor oral absorption of ginsenoside Rb1 (Rb1), one main ingredient of the well known Panax notoginseng saponins (PNS) for curing hemorrhage. Caco-2 cell monolayers were used as an in vitro model to reveal the transport mechanism of Rb1 across the intestinal mucosa. Moreover, the serum concentration-time profiles of Rb1 after tail venous (IV), portal venous (PV), intraduodenal (ID) and peroral (PO) administration to rats were compared to evaluate the first-pass effects of stomach, intestine and liver. In vitro experiments showed that uptake by Caco-2 cell monolayers was temperature dependent, but was not influenced by cyclosporine A and ketoconazole. The change in the apical pH showed no obvious effects on the uptake of Rb1. The uptake and transport were non-saturable, and flux from the apical compartment to the basolateral compartment (A-B) increased linearly with increasing concentration, which indicated a passive transport. Meanwhile, an apparent permeability coefficient of (5.90 +/- 1.02) x 10(-8) cm/s (C0 = 1 mg/mL) predicted an incomplete absorption. The investigation on the pharmacokinetic behavior of Rb1 after different routes of administration to rats showed a significant difference between PO (F(PO) was 0.64%), ID (F(ID) was 2.46%) and PV (F(PV) was 59.49%) administration, and the first-pass effect of the intestine is more significant than that of the stomach and liver in the absorption process. In summary, elimination in the stomach, large intestine and liver contributed to the poor absorption of Rb1, but the low membrane permeability might be a more important factor dominating the extent of absorption.

  10. Validity of the linear viscoelastic model for a polymer cylinder with ultrasonic hysteresis-type absorption in a nonviscous fluid

    CERN Document Server

    Mitri, F G

    2016-01-01

    A necessary condition for the validity of the linear viscoelastic model for a (passive) polymeric cylinder with an ultrasonic hysteresis-type absorption submerged in a non-viscous fluid requires that the absorption efficiency is positive (Qabs > 0) satisfying the law of the conservation of energy. This condition imposes restrictions on the values attributed to the normalized absorption coefficients for the compressional and shear-wave wavenumbers for each partial-wave mode n. The forbidden values produce negative axial radiation force, absorption and extinction efficiencies, as well as an enhancement of the scattering efficiency, not in agreement with the conservation of energy law. Numerical results for the radiation force, extinction, absorption and scattering efficiencies are performed for three viscoelastic (VE) polymer cylinders immersed in a non-viscous host liquid (i.e. water) with particular emphasis on the shear-wave absorption coefficient of the cylinder, the dimensionless size parameter and the par...

  11. Semi-mechanistic modelling of ammonia absorption in an acid spray wet scrubber based on mass balance

    Science.gov (United States)

    A model to describe reactive absorption of ammonia (NH3) in an acid spray scrubber was developed as a function of the combined overall mass transfer coefficient K. An experimental study of NH3 absorption using 1% dilute sulphuric acid was carried out under different operating conditions. An empiric...

  12. Modeling of the Interminiband Absorption Coefficient in InGaN Quantum Dot Superlattices

    Directory of Open Access Journals (Sweden)

    Giovanni Giannoccaro

    2016-01-01

    Full Text Available In this paper, a model to estimate minibands and theinterminiband absorption coefficient for a wurtzite (WZ indium gallium nitride (InGaN self-assembled quantum dot superlattice (QDSL is developed. It considers a simplified cuboid shape for quantum dots (QDs. The semi-analytical investigation starts from evaluation through the three-dimensional (3D finite element method (FEM simulations of crystal mechanical deformation derived from heterostructure lattice mismatch under spontaneous and piezoelectric polarization effects. From these results, mean values in QDs and barrier regions of charge carriers’ electric potentials and effective masses for the conduction band (CB and three valence sub-bands for each direction are evaluated. For the minibands’ investigation, the single-particle time-independent Schrödinger equation in effective mass approximation is decoupled in three directions and resolved using the one-dimensional (1D Kronig–Penney model. The built-in electric field is also considered along the polar axis direction, obtaining Wannier–Stark ladders. Then, theinterminiband absorption coefficient in thermal equilibrium for transverse electric (TE and magnetic (TM incident light polarization is calculated using Fermi’s golden rule implementation based on a numerical integration into the first Brillouin zone. For more detailed results, an absorption coefficient component related to superlattice free excitons is also introduced. Finally, some simulation results, observations and comments are given.

  13. Modeling And Experimental Analysis Of Generator In Vapour Absorption Refrigeration System

    Directory of Open Access Journals (Sweden)

    Christy V Vazhappilly

    2013-09-01

    Full Text Available A breadboard prototype of an absorption system for refrigeration using heat from the exhaust-gases is to be designed, built and tested. In the commercial vapour absorption refrigeration system a heating coil generator system has been employed to vaporize the ammonia efrigerant. In the present work, the heating coil generator system has been replaced by the frame plate type heat exchanger. The exhaust gases from the IC engine have been utilized to vaporize the ammonia refrigerant. The available heat in the exhaust gases has to be estimated based on actual I.C-Engine driving cycles. The frame plate type heat exchanger has to be modeled and flow analysis inside the heat exchanger has to be analyzed. In addition, the recoverable energy of the exhaust gases is to be analyzed for representative Internal Combustion Engine.

  14. Effects of changing the amount of absorption in a computer model of Queen's Hall, Copenhagen, Denmark

    DEFF Research Database (Denmark)

    Vigeant, Michelle C.; Wang, Lily M.; Rindel, Jens Holger

    2006-01-01

    of modelling the source directivity. A new method to incorporate source directivity is multi-channel auralizations. An omni-directional source is divided into the number of recording channels and the impulse response (IR) for each channel is calculated. Each individual IR is then convolved with the appropriate...... recording, and a final auralization is created by mixing all individual channel auralizations together. This study evaluates the objective and subjective effects of using four and thirteen channel IRs in an ODEON model of Queen’s Hall, a hall located in Copenhagen with variable absorption. Analyses...

  15. Modeling swelling and absorption dynamics for holographic sensing in analytes sensitive photopolymer

    Science.gov (United States)

    Liu, Hongpeng; Yu, Dan; Mao, Dongyao; Geng, Yaohui; Wang, Weibo

    2016-06-01

    A theoretical model is developed to describe holographic sensing and swelling of grating fringe in photopolymer. In experiments, diffraction spectrum responses of grating are characterized to exhibit holographic sensing processes. Analytic expressions between swelling of grating fringe and environmental factors, such as relative humidity and organic vapor concentrations, are extracted based on experimental results. The primary factors are introduced into the model to simulate the sensing process, including swelling ratio, nanozeolites dispersion, and organic vapor absorption. Finally, numerical results are presented for improving the sensitivity of holographic sensor. This work can accelerate the development of holographic sensor and provide a theoretical base for exploring sensing mechanism of polymer.

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

    Science.gov (United States)

    Miao, D.

    1978-01-01

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

  17. Submodels of model of nonlinear diffusion in the inhomogeneous medium involving absorption

    Energy Technology Data Exchange (ETDEWEB)

    Chirkunov, Yu. A., E-mail: chr101@mail.ru [Novosibirsk State Technical University, Marks Avenue 20, Novosibirsk 630073 (Russian Federation)

    2015-10-15

    We study the five-parameter model, describing the process of nonlinear diffusion in an inhomogeneous medium in the presence of absorption, for which the differential equation of the model admits a continuous Lie group of transformations, acting on the set of its solutions. We found six submodels of the original model of nonlinear diffusion, with different symmetry properties. Of these six submodels, the five submodels with transient absorption, for which the absorption coefficient depends on time according to a power law, represent the greatest interest with a mathematical point of view and with the point of view of physical applications. For each of these nonlinear submodels, we obtained formulas for producing new solutions that contain arbitrary constants, and we found all invariant submodels. All essentially distinct invariant solutions describing these invariant submodels are found in an explicit form or are reduced to finding the solution of nonlinear integral equations. The presence of the arbitrary constants in the integral equations that determine these solutions provide new opportunities for analytical and numerical study of boundary value problems for the received submodels and, thus, for the original model of nonlinear diffusion. For the received invariant submodels, we studied diffusion processes for which at the initial moment of the time at a fixed point is specified as a concentration and its gradient or as a concentration and its velocity. Solving of boundary value problems describing these processes is reduced to the solving of nonlinear integral equations. We established the existence and uniqueness of solutions of these boundary value problems under some additional conditions. The obtained results can be used to study the diffusion of substances, diffusion of conduction electrons and other particles, diffusion of physical fields and propagation of heat in inhomogeneous medium, and also to study a turbulence (Leith model, differential

  18. Modeling of water absorption induced cracks in resin-based composite supported ceramic layer structures.

    Science.gov (United States)

    Huang, Min; Thompson, V P; Rekow, E D; Soboyejo, W O

    2008-01-01

    Cracking patterns in the top ceramic layers of the modeled dental multilayers with polymer foundation are observed when they are immersed in water. This article developed a model to understand this cracking mechanism. When water diffuses into the polymer foundation of dental restorations, the foundation will expand; as a result, the stress will build up in the top ceramic layer because of the bending and stretching. A finite element model based on this mechanism is built to predict the stress build-up and the slow crack growth in the top ceramic layers during the water absorption. Our simulations show that the stress build-up by this mechanism is high enough to cause the cracking in the top ceramic layers and the cracking patterns predicted by our model are well consistent with those observed in experiments on glass/epoxy/polymer multilayers. The model is then used to discuss the life prediction of different dental ceramics. PMID:17497681

  19. Predicting dermal absorption of gas-phase chemicals: transient model development, evaluation, and application

    DEFF Research Database (Denmark)

    Gong, M.; Zhang, Y.; Weschler, Charles J.

    2014-01-01

    for scenarios in which (A) a previously unexposed occupant encounters gas-phase phthalates in three different environments over a single 24-h period; (B) the same as 'A', but the pattern is repeated for seven consecutive days. In the 24-h scenario, the transient model predicts more phthalate absorbed into skin......A transient model is developed to predict dermal absorption of gas-phase chemicals via direct air-to-skin-to-blood transport under non-steady-state conditions. It differs from published models in that it considers convective mass-transfer resistance in the boundary layer of air adjacent to the skin...... and less absorbed into blood than would a steady-state model. In the 7-day scenario, results calculated by the transient and steady-state models converge over a time period that varies between 3 and 4days for all but the largest phthalate (DEHP). Dermal intake is comparable to or larger than inhalation...

  20. Difference in oral absorption of ginsenoside Rg1 between in vitro and in vivo models

    Institute of Scientific and Technical Information of China (English)

    Min HAN; Xiao-ling FANG

    2006-01-01

    Aim:To clarify the cause of poor oral absorption of ginsenoside Rg1 (Rg1) ,the active ingredient in Panax notoginseng saponins (PNS) used for treating hemorrhage.Methods:Caco-2 cell monolayers were used as an in vitro model to study the transport mechanism of Rg1 across the intestinal mucosa.Moreover,the serum concentration-time profiles after peroral (po) ,intraduodenal (id) ,portal venous (pv) and tail venous (iv) administration of Rg1 in rats were compared to evaluate the first-pass effects in the stomach.intestine,and liver.Results:Uptake of Rg1 by Caco-2 cell monolayers was temperature-dependent,but was not influenced by cyclosporin A.The change in the apical pH produced no obvious effect on the uptake of Rg1.The uptake and transport of Rg1 was non-saturable;whereas the flux from the apical compartment to the basolateral compartment (A-B) increased in a linear manner with the increase in concentration,indicating passive transport.An apparent permeability coefficient of (2.59±0.17)×10-7 cm/s (C0=1mg/mL) predicted incomplete absorption.A significant difference was observed between the po (Fpo was 3.29% at a dose of 1500 mg/kg) ,id (Fid was 6.60% at a dose of 1200 mg/kg) and pv (Fpv was 50.56%) administration methods,and the barrier function of the intestine was more significant than those of the stomach and liver in the absorption process.Conclusion:Elimination in the stomach.large intestine and liver contributed to the low oral bioavailability of Rg,but low membrane permeability might be a more important factor in determining the extent of absorption.

  1. EVALUATION OF THE STRUCTURAL FUNDS ABSORPTION RATE BY MEANS OF THE HERMIN MODEL

    Directory of Open Access Journals (Sweden)

    Opritescu Elena Madalina

    2012-07-01

    Full Text Available The main objective of this article is to highlight the main method that could quantify the impact of the structural funds on the Gross Domestic Product. I also presented the regional disparities situation and the European funds absorption rate. The HERMIN model has been designed considering the evolution of macro-variables throughout transition and pre-accession process, as well as out of the need to analyze the gradual alignment of Romania’s economic policies to those of EU. The fact that, initially, the HERMIN model was designed for the European Union’s less developed economies represented the cornerstone in choosing it, as it was the case for Romania, too. However, the quantitative evaluation must always be accompanied by a qualitative evaluation, in order to comprise factors which cannot be measured by the econometrical modeling. For this purpose, when the results of econometrical model based evaluation are used, it is important to be aware of the fact that models simplify reality, no matter the impressive mathematical calculations they employ. Also, we must not omit the fact that Romania’s major development needs and the current economic context imperatively demand a high as possible level of structural funds absorption, as well as their efficient use, meant to generate a significant impact at a national, regional and local level. One of the main instruments employed to sustain economic growth, while also reducing disparities between regions is represented by the structural funds. These funds, consisting in financial contributions of the member states, according to their level of development, are redistributed in compliance with an extremely complex regulating and procedural frame, to those EU states of regions which are fallen behind from a social and economical development perspective Nevertheless, when absorption capacity of a member state is evaluated, the used percentage from the allocated funds is not the only

  2. Modeling the Performance of a Spaceborne Laser Absorption Spectrometer for Atmospheric CO2 Column Measurements

    Science.gov (United States)

    Lin, B.; Ismail, S.; Harrison, F. W.; Browell, E. V.; Nehrir, A. R.; Dobler, J. T.; Moore, B.; Refaat, T.; Kooi, S. A.

    2013-12-01

    Accurate global observations of atmospheric carbon dioxide (CO2) with a laser-based space mission, such as the NASA ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) mission, are crucial to improving our understanding of global CO2 sources and sinks. This study focuses on modeling of the performance of a spaceborne laser absorption spectrometer (LAS) system for CO2 column measurements. The model accounts for all of the fundamental physics of the instrument subsystems and components and the influences of measurement environments. The characteristics of simulated LAS systems and their components are based on existing technologies and the implementation of operational systems. The modeled instrument is specifically assumed to be an Intensity-Modulated Continuous-Wave (IM-CW) LAS system like the Exelis airborne Multifunctional Fiber Laser Lidar (MFLL) operating in the 1.57 um CO2 absorption band. Environmental effects such as gas absorption, solar radiation, scattering of aerosols and thin clouds, atmospheric turbulence, and surface reflection are also considered in the model. The modeled results are presented statistically from simulation ensembles of multiple model runs to accurately represent the random nature of all of the noise sources and uncertainties related to the LAS instruments and the measurement environments. Model simulations demonstrate very good agreement when compared to prior airborne and ground based MFLL measurements. The model predicted lidar return powers for various calibrated surface targets show good agreement with those measured by the MFLL instrument during ground tests at NASA Langley Research Center in the summer of 2012. The difference between modeled and measured signal-to-noise ratios (SNR) of the LAS CO2 column optical depths (Tau_d) for the summer 2011 flight campaign on board the NASA DC-8 over Railroad Valley (RRV), NV is generally within 20%. The simulations for spaceborne Tau_d measurements over RRV indicate

  3. Application of absorption modeling to predict bioequivalence outcome of two batches of etoricoxib tablets.

    Science.gov (United States)

    Mitra, Amitava; Kesisoglou, Filippos; Dogterom, Peter

    2015-02-01

    As part of the overall product development and manufacturing strategy, pharmaceutical companies routinely change formulation and manufacturing site. Depending on the type and level of change and the BCS class of the molecule, dissolution data and/or bioequivalence (BE) may be needed to support the change for immediate release dosage forms. In this report, we demonstrate that for certain weakly basic low-solubility molecules which rapidly dissolve in the stomach, absorption modeling could be used to justify a BE study waiver even when there is failure to show dissolution similarity under some conditions. The development of an absorption model for etoricoxib is described here, which was then used to a priori predict the BE outcome of tablet batches manufactured at two sites. Dissolution studies in 0.01 N HCl media (pH 2.0) had demonstrated similarity of etoricoxib tablets manufactured at two different sites. However, dissolution testing at pH 4.5 and pH 6.8 media failed to show comparability of the tablets manufactured at the two sites. Single simulations and virtual trials conducted using the 0.01 N HCl dissolution showed similarity in AUC and C max for all tablet strengths for batches manufactured at the two manufacturing sites. These predicted results were verified in a definitive bioequivalence study, which showed that both tablet batches were bioequivalent. Since the development of traditional in vitro-in vivo correlations (IVIVC) for immediate release (IR) products is challenging, in cases such as etoricoxib, absorption modeling could be used as an alternative to support waiver of a BE study. PMID:25182387

  4. Excited-state characterization and effective three-photon absorption model of two-photon-induced excited-state absorption in organic push-pull charge-transfer chromophores

    International Nuclear Information System (INIS)

    We report experimental investigations of two-photon and excited-state absorption in D-π-A chromophores and propose a model to explain nonlinear absorption in the nanosecond regime. The key parameter is an effective three-photon absorption coefficient that depends on the two-photon absorption cross section and excited-state photophysical properties. We obtain all these parameters from independent measurements and then compare the model with nanosecond nonlinear transmission measurements. We find good agreement with the data, using no free parameters, for specific values of some published two-photon absorption cross sections. We conclude that excited singlet-singlet and triplet-triplet absorption are the dominant sources of nonlinear transmittance loss and that the chief role of two-photon absorption is to populate these states

  5. The energy spectrum and the optical absorption spectrum of C{sub 60} fullerene within the Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Silant’ev, A. V., E-mail: kvvant@rambler.ru [Mari State University (Russian Federation)

    2015-10-15

    Anticommutator Green’s functions and the energy spectrum of C{sub 60} fullerene are calculated in the approximation of static fluctuations within the Hubbard model. On the basis of this spectrum, an interpretation is proposed for the experimentally observed optical absorption bands of C{sub 60} fullerene. The parameters of C{sub 60} fullerene that characterize it within the Hubbard model are calculated by the optical absorption spectrum.

  6. Thermodynamic and kinetics models of hydrogen absorption bound to phase transformations; Modelisation thermodynamique et cinetiques d'absorption d'hydrogene associees aux transformations de phase

    Energy Technology Data Exchange (ETDEWEB)

    Gondor, G.; Lexcellent, Ch. [Institut FEMTO-ST, Lab. de Mecanique Appliquee R. Chaleat (LMARC), 25 - Besancon (France)

    2007-07-01

    In order to design hydrogen gaseous pressure tanks, the absorption (desorption) of hydrogen has to be described and modelled. The equilibrium state can be described by the 'H{sub 2} gas pressure - H{sub 2} composition in the intermetallic compounds - isotherms' (PCI) curves. Several models of PCI curves already exist. At the beginning of the absorption, the hydrogen atoms and the intermetallic compounds form a solid solution ({alpha} phase). When the hydrogen concentration increases, a phase transformation appears changing the {alpha} solid solution into an hydride ({beta} phase) (solid solution + H{sub 2} {r_reversible} hydride). When all the solid solution has been transformed into hydride, the absorbed hydrogen atoms are in {beta} phase. A new thermodynamic model has been developed in order to take into account this transition phase. The equilibrium state is then given by a relation between the H{sub 2} gas pressure and the H{sub 2} concentration in the intermetallic compound for a fixed external temperature. Two kinetics models have been developed too; at first has been considered that the kinetics depend only of the entire concentration in the intermetallic compound and of the difference between the applied pressure and the equilibrium pressure. Then, has been considered that the hydrogen concentration changes in the metallic matrix. In this last case, for each hydrogenation process, the absorption velocity is calculated to determine the slowest local process which regulates the local evolution of the hydrogen concentration. These two models are based on the preceding thermodynamic model of the PCI curves. (O.M.)

  7. Multiple Absorption-Line Spectroscopy of the Intergalactic Medium. I. Model

    CERN Document Server

    Yao, Yangsen; Danforth, Charles W; Keeney, Brian A; Stocke, John T

    2011-01-01

    We present a physically-based absorption-line model for the spectroscopic study of the intergalactic medium (IGM). This model adopts results from Cloudy simulations and theoretical calculations by Gnat and Sternberg (2007) to examine the resulting observational signatures of the absorbing gas with the following ionization scenarios: collisional ionization equilibrium (CIE), photoionization equilibrium, hybrid (photo- plus collisional ionization), and non-equilibrium cooling. As a demonstration, we apply this model to new observations made with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope of the IGM absorbers at z~0.1877 along the 1ES 1553+113 sight line. We identify Ly alpha, C III, O VI, and N V absorption lines with two distinct velocity components (blue at z_b=0.18757; red at z_r=0.18772) separated by Delta(cz)/(1+z)~38 km/s. Joint analyses of these lines indicate that none of the examined ionization scenarios can be applied with confidence to the blue velocity component, although phot...

  8. ISMabs: A COMPREHENSIVE X-RAY ABSORPTION MODEL FOR THE INTERSTELLAR MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Gatuzz, E.; Mendoza, C. [Centro de Física, Instituto Venezolano de Investigaciones Científicas (IVIC), P.O. Box 20632, Caracas 1020A (Venezuela, Bolivarian Republic of); García, J. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138 (United States); Kallman, T. R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gorczyca, T. W., E-mail: egatuzz@ivic.gob.ve, E-mail: claudio@ivic.gob.ve, E-mail: javier@head.cfa.harvard.edu, E-mail: timothy.r.kallman@nasa.gov, E-mail: thomas.gorczyca@wmich.edu [Department of Physics, Western Michigan University, Kalamazoo, MI 49008 (United States)

    2015-02-10

    We present an X-ray absorption model for the interstellar medium, to be referred to as ISMabs, that takes into account both neutral and ionized species of cosmically abundant elements, and includes the most accurate atomic data available. Using high-resolution spectra from eight X-ray binaries obtained with the Chandra High Energy Transmission Grating Spectrometer, we proceed to benchmark the atomic data in the model particularly in the neon K-edge region. Compared with previous photoabsorption models, which solely rely on neutral species, the inclusion of ions leads to improved spectral fits. Fit parameters comprise the column densities of abundant contributors that allow direct estimates of the ionization states. ISMabs is provided in the appropriate format to be implemented in widely used X-ray spectral fitting packages such as XSPEC, ISIS, and SHERPA.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hernández S, A., E-mail: h.s.alfonso@gmail.com, E-mail: meduardo2001@hotmail.com; Cano, M. E., E-mail: h.s.alfonso@gmail.com, E-mail: meduardo2001@hotmail.com [Centro Universitario de la Ciénega, Universidad de Guadalajara, Ocotlán, Jalisco (Mexico); Torres-Arenas, J., E-mail: torresare@gmail.com [Division de Ciencias e Ingenierías, Universidad de Guanajuato, León, Guanajuato (Mexico)

    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.

  10. Modeling of gamma-ray energy absorption buildup factors using response surface method

    International Nuclear Information System (INIS)

    Buildup factors are always useful for practical computations in gamma-ray shield design. Generally point kernel method being easier to handle is adopted for shielding calculations. This method models a gamma ray directly at the evaluation point without scattering which is multiplied by buildup factors to obtain the gamma dose rate. The American Nuclear Society Standard Committee working group (ANSI/ANS-6.4.3-1991) has compiled the energy absorption and exposure buildup factors from 1 mean free path to 40 mean free paths as a standard reference data base for a large number of elements including water, air and concrete. Literature study reveals that there is a substantially significant disagreement in the buildup factor data by different approximating formulae. In view of this, it is required to compute or predict the buildup factor for those materials. The buildup factor data have been computed by various codes. Some of the codes are ASFIT (Gopinath and Sakamoto et al, 1971), PALLAS (Takeuchi and Tanaka, 1984) and EGS4 (Nelson et al, 1985). Taylor (1954), Berger (1956), Capo (1958) have fitted Goldstein and Wilkins (1954) data to construct parametric buildup factor formulae. Harimaet et al. (1986) has developed geometric progress fitting formula for the ANSI/ANS-6.4.3 (ANSI, 1991). The energy absorption buildup factor is defined as the photon buildup factor in which the quantity of interest is the absorbed or deposited energy in the shield medium and the detector response function is that of absorption in the material. Geometric progression buildup factor formula was simplified using the new modeling (fitting algorithm) of gamma ray energy absorption buildup factor. Advantage of having the simplification of buildup factor formula provides the easiness of usage of point kernel method based gamma shielding in the sense that analytic expression of collided flux can be easily constructed. Furthermore, that analytical expression of collided flux can be optimized to

  11. CO2 Absorption in a Lab-Scale Fixed Solid Bed Reactor: Modelling and Experimental Tests

    Directory of Open Access Journals (Sweden)

    Roberto Gabbrielli

    2004-09-01

    Full Text Available The CO2 absorption in a lab-scale fixed solid bed reactor filled with different solid sorbents has been studied under different operative conditions regarding temperature (20-200°C and input gas composition (N2, O2, CO2, H2O at 1bar pressure. The gas leaving the reactor has been analysed to measure the CO2 and O2 concentrations and, consequently, to evaluate the overall CO2 removal efficiency. In order to study the influence of solid sorbent type (i.e. CaO, coal bottom ash, limestone and blast furnace slag and of mass and heat transfer processes on CO2 removal efficiency, a one-dimensional time dependent mathematical model of the reactor, which may be considered a Plug Flow Reactor, has been developed. The quality of the model has been confirmed using the experimental results.

  12. Generation and Active Absorption of 2- and 3-Dimensional Linear Water Waves in Physical Models

    DEFF Research Database (Denmark)

    Christensen, Morten

    in the wave channel in front of the wave generator. The results of physical model tests performed with an absorbing wave maker based on this principle show that the problem of rereflection is reduced significantly when active absorption is performed. Finally, an absorbing directional wave generator for 3-D......Methods for mechanical generation of 2-dimensional (2-D) and 3-dimensional (3-D) linear water waves in physical models are presented. The results of a series of laboratory 3-D wave generation tests are presented and discussed. The tests preformed involve reproduction of wave fields characterised...... by different directional wave spectra. The wave generator displacement signals applied in the tests are generated by means of linear digital filtering of Gaussian white noise in the time domain. An absorbing wave generator for 2-D wave facilities (wave channels) is developed. The absorbing wave generator...

  13. Thermodynamic modeling and performance analysis of the variable-temperature heat reservoir absorption heat pump cycle

    Science.gov (United States)

    Qin, Xiaoyong; Chen, Lingen; Ge, Yanlin; Sun, Fengrui

    2015-10-01

    For practical absorption heat pump (AHP) plants, not all external heat reservoir heat capacities are infinite. External heat reservoir heat capacity should be an effect factor in modeling and performance analysis of AHP cycles. A variable-temperature heat reservoir AHP cycle is modeled, in which internal working substance is working in four temperature levels and all irreversibility factors are considered. The irreversibility includes heat transfer irreversibility, internal dissipation irreversibility and heat leakage irreversibility. The general equations among coefficient of performance (COP), heating load and some key characteristic parameters are obtained. The general and optimal characteristics are obtained by using numerical calculations. Besides, the influences of heat capacities of heat reservoirs, internal dissipation irreversibility, and heat leakage irreversibility on cycle performance are analyzed. The conclusions can offer some guidelines for design and operation of AHP plants.

  14. Shape dependency of the extinction and absorption cross sections of dust aerosols modeled as randomly oriented spheroids

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2011-09-01

    Full Text Available We present computational results on the shape dependency of the extinction and absorption cross sections of dustlike aerosol particles that were modeled as randomly oriented spheroids. Shape dependent variations in the extinction cross sections are largest in the size regime that is governed by the interference structure. Elongated spheroids best fitted measured extinction spectra of re-dispersed Saharan dust samples. For dust particles smaller than 1.5 μm in diameter and low absorption potential, shape effects on the absorption cross sections are very small.

  15. NLP model based thermoeconomic optimization of vapor compression–absorption cascaded refrigeration system

    International Nuclear Information System (INIS)

    Highlights: • It addresses the size and cost estimation of cascaded refrigeration system. • Cascaded system is a promising decarburizing and energy efficient technology. • Second law analysis is carried out with modified Gouy-Stodola equation. • The total annual cost of plant operation is optimized in present work. - Abstract: This paper addresses the size and cost estimation of vapor compression–absorption cascaded refrigeration system (VCACRS) for water chilling application taking R410a and water–LiBr as refrigerants in compression and absorption section respectively which can help the design engineers in manufacturing and experimenting on such kind of systems. The main limitation in the practical implementation of VCACRS is its size and cost which are optimized in the present work by implementing Direct Search Method in non-linear programming (NLP) mathematical model of VCACRS. The main objective of optimization is to minimize the total annual cost of system which comprises of costs of exergy input and capital costs in monetary units. The appropriate set of decision variables (temperature of evaporator, condenser, generator, absorber, cascade condenser, degree of overlap and effectiveness of solution heat exchanger) minimizes the total annual cost of VCACRS by 11.9% with 22.4% reduction in investment cost at the base case whereas the same is reduced by 7.5% with 11.7% reduction in investment cost with reduced rate of interest and increased life span and period of operation. Optimization results show that the more investment cost in later case is well compensated through the performance and operational cost of the system. In the present analysis, optimum cascade condensing temperature is a strong function of period of operation and capital recovery factor. The cascading of compression and absorption systems becomes attractive for lower rate of interest and increase life span and operational period

  16. Electromagnetically induced absorption in detuned stub waveguides: a simple analytical and experimental model.

    Science.gov (United States)

    Mouadili, A; Boudouti, E H El; Soltani, A; Talbi, A; Djafari-Rouhani, B; Akjouj, A; Haddadi, K

    2014-12-17

    We give an analytical and experimental demonstration of a classical analogue of the electromagnetic induced absorption (EIA) in a simple photonic device consisting of two stubs of lengths d1 and d2 grafted at the same site along a waveguide. By detuning the lengths of the two stubs (i.e. δ = d(2) - d(1)) we show that: (i) the amplitudes of the electromagnetic waves in the two stubs can be written following the two resonators model where each stub plays the role of a radiative resonator with low Q factor. The destructive interference between the waves in the two stubs may give rise to a sharp resonance peak with high Q factor in the transmission as well as in the absorption. (ii) The transmission coefficient around the resonance induced by the stubs can be written following a Fano-like form. In particular, we give an explicit expression of the position, width and Fano parameter of the resonances as a function of δ. (iii) By taking into account the loss in the waveguides, we show that at the transmission resonance, the transmission (reflection) increases (decreases) as a function of δ. Whereas the absorption goes through a maximum around 0.5 for a threshold value δth which depends on the attenuation in the system and then falls to zero. (iv) We give a comparison between the phase of the determinant of the scattering matrix, the so-called Friedel phase and the phase of the transmission amplitude. (v) The effect of the boundary conditions at the end of the resonators on the EIA resonance is also discussed. The analytical results are obtained by means of the Green's function method, whereas the experiments are carried out using coaxial cables in the radio-frequency regime. These results should have important consequences for designing integrated devices such as narrow-frequency optical or microwave filters and high-speed switches. PMID:25406973

  17. A model of ruminal volatile fatty acid absorption kinetics and rumen epithelial blood flow in lactating Holstein cows

    DEFF Research Database (Denmark)

    Storm, Adam Christian; Kristensen, Niels Bastian; Hanigan, Mark D

    2012-01-01

    . Parameter estimates were derived by fitting the model to observed data. The model provided reliable unbiased estimates of ruminal VFA absorption and rumen epithelial blood flow. Blood flow was modeled using an equation that considered the effect of butyrate and dietary crude protein intake per kilogram...

  18. Modeling of high frequency radio wave absorption on oblique soundings during a solar X-ray flare

    Science.gov (United States)

    Rogov, D. D.; Moskaleva, E. V.; Zaalov, N. Y.

    2015-01-01

    High frequency radio wave absorption induced by Solar Ultra-Violet (UV) and X-ray flux is investigated. The influence of the solar flare observed on 11 April 2013 on the structure of oblique sounding ionograms in the Arctic region of Russia is considered. An adjustable model of the ionosphere developed for high frequency (HF) propagation problems was employed for this purpose. The simulation algorithm has been designed to accept a large variety of ionospheric conditions. On the basis of the SWPC D-region Absorption model the absorption effects in the ionosphere at sub-auroral latitudes of the Earth were calculated. This approach does not require knowledge of the electron density and electron collision frequency profiles of the D-region ionosphere. The oblique ionograms simulated with the absorption effect and ionograms provided by Russian network of ionospheric observations deployed in Arctic region exhibit quite a good resemblance.

  19. Modeling and optimization of CO2 capture processes by chemical absorption

    International Nuclear Information System (INIS)

    CO2 capture processes by chemical absorption lead to a large energy penalty on efficiency of coal-fired power plants, establishing one of the main bottleneck to its industrial deployment. The objective of this thesis is the development and validation of a global methodology, allowing the precise evaluation of the potential of a given amine capture process. Characteristic phenomena of chemical absorption have been thoroughly studied and represented with state-of-the-art models. The e-UNIQUAC model has been used to describe vapor-liquid and chemical equilibria of electrolyte solutions and the model parameters have been identified for four solvents. A rate-based formulation has been adopted for the representation of chemically enhanced heat and mass transfer in columns. The absorption and stripping models have been successfully validated against experimental data from an industrial and a laboratory pilot plants. The influence of the numerous phenomena has been investigated in order to highlight the most limiting ones. A methodology has been proposed to evaluate the total energy penalty resulting from the implementation of a capture process on an advanced supercritical coal-fired power plant, including thermal and electric consumptions. Then, the simulation and process evaluation environments have been coupled with a non-linear optimization algorithm in order to find optimal operating and design parameters with respect to energetic and economic performances. This methodology has been applied to optimize five process flow schemes operating with an monoethanolamine aqueous solution at 30% by weight: the conventional flow scheme and four process modifications. The performance comparison showed that process modifications using a heat pump effect give the best gains. The use of technical-economic analysis as an evaluation criterion of a process performance, coupled with a optimization algorithm, has proved its capability to find values for the numerous operating and design

  20. Influence of absorption on the X-ray diffraction by the trapeziform model of superlattice with a stacking fault

    Science.gov (United States)

    Manukyan, H. M.; Manukyan, S. M.

    2016-07-01

    The problem of a dynamic diffraction of a plane monochromatic X-ray wave at the absorbing superlattice with a stacking fault between the layers for the trapeziform model of superlattice is considered. It is shown, that presence of stacking fault reduces the anomalous absorption. The interference absorption depends on the shift vector and depth of the stacking fault and the structural factor of superlattice.

  1. Integrated numerical model of nitrogen transportation, absorption and transformation by two-dimension in soil-crop system

    Institute of Scientific and Technical Information of China (English)

    WANG Hong-qi; SHU Yan; QI Yong-qiang; ZHANG Jun

    2005-01-01

    A series of simulation experiments of nitrogen transportation, absorption and transformation were conducted, and the different cropping patterns of winter wheat and wastewater irrigation plans were taken into consideration. Based on the experiments, an integrated model of crop growth, roots distribution, water and nitrogen absorption by roots, water and nitrogen movement and transformation in soilcrop system by two-dimension was developed. Parameters and boundary conditions were identified and an effective computing method for optimizing watering and wastewater irrigating plans was provided.

  2. Modelling millimetre wave propagation and absorption in a high resolution skin model: the effect of sweat glands

    Science.gov (United States)

    Shafirstein, Gal; Moros, Eduardo G.

    2011-03-01

    The aim of this work was to investigate the potential effect of sweat gland ducts (SGD) on specific absorption rate (SAR) and temperature distributions during mm-wave irradiation. High resolution electromagnetic and bio-heat transfer models of human skin with SGD were developed using a commercially available simulation software package (SEMCAD X™). The skin model consisted of a 30 µm stratum corneum, 350 µm epidermis and papillary dermis (EPD) and 1000 µm dermis. Five SGD of 60 µm radius and 300 µm height were embedded linearly with 370 µm separation. A WR-10 waveguide positioned 20 µm from the skin surface and delivering 94 GHz electromagnetic radiation was included in the model. Saline conductivity was assigned inside SGD. SAR and temperatures were computed with and without SGD. Despite their small scale, SAR was significantly higher within SGD than in the EPD without SGD. Without SGD, SAR and temperature maxima were in the dermis near EPD. With SGD, SAR maximum was inside SGD while temperature maximum moved to the EPD/stratum-corneum junction. Since the EPD participates actively in perception, the effect of SGD should be taken into account in nociceptive studies involving mm-waves. This research represents a significant step towards higher spatial resolution numerical modelling of the skin and shows that microstructures can play a significant role in mm-wave absorption and induced temperature distributions.

  3. Modelling millimetre wave propagation and absorption in a high resolution skin model: the effect of sweat glands

    Energy Technology Data Exchange (ETDEWEB)

    Shafirstein, Gal [Department of Otolaryngology, College of Medicine, University of Arkansas for Medical Sciences, 4301 W. Markham, 543, Little Rock, AR 72205 (United States); Moros, Eduardo G, E-mail: shafirsteingal@uams.edu [Division of Radiation Physics and Informatics, Department of Radiation Oncology, College of Medicine, University of Arkansas for Medical Sciences, 4301 W. Markham, 771, Little Rock, AR 72205 (United States)

    2011-03-07

    The aim of this work was to investigate the potential effect of sweat gland ducts (SGD) on specific absorption rate (SAR) and temperature distributions during mm-wave irradiation. High resolution electromagnetic and bio-heat transfer models of human skin with SGD were developed using a commercially available simulation software package (SEMCAD X(TM)). The skin model consisted of a 30 {mu}m stratum corneum, 350 {mu}m epidermis and papillary dermis (EPD) and 1000 {mu}m dermis. Five SGD of 60 {mu}m radius and 300 {mu}m height were embedded linearly with 370 {mu}m separation. A WR-10 waveguide positioned 20 {mu}m from the skin surface and delivering 94 GHz electromagnetic radiation was included in the model. Saline conductivity was assigned inside SGD. SAR and temperatures were computed with and without SGD. Despite their small scale, SAR was significantly higher within SGD than in the EPD without SGD. Without SGD, SAR and temperature maxima were in the dermis near EPD. With SGD, SAR maximum was inside SGD while temperature maximum moved to the EPD/stratum-corneum junction. Since the EPD participates actively in perception, the effect of SGD should be taken into account in nociceptive studies involving mm-waves. This research represents a significant step towards higher spatial resolution numerical modelling of the skin and shows that microstructures can play a significant role in mm-wave absorption and induced temperature distributions.

  4. Radial diffusion in the Uranian radiatian belts - Inferences from satellite absorption loss models

    Science.gov (United States)

    Hood, L. L.

    1989-01-01

    Low-energy charged particle (LECP) phase space density profiles available from the Voyager/1986 Uranus encounter are analyzed, using solutions of the time-averaged radial diffusion equation for charged particle transport in a dipolar planetary magnetic field. Profiles for lower-energy protons and electrons are first analyzed to infer radial diffusion rate as a function of L, assuming that satellite absorption is the dominant loss process and local sources for these particles are negligible. Satellite macrosignatures present in the experimentally derived profiles are approximately reproduced in several cases, lending credence to the loss model and indicating that magnetospheric distributed losses are not as rapid as satellite absorption near the minimum satellite L shells for the particles. Diffusion rates and L dependences are found to be similar to those previously inferred in the inner Jovian magnetosphere (Thomsen et al., 1977) and for the inner Saturnian magnetosphere (Hood, 1985). Profiles for higher energy electrons and protons are also analyzed using solutions that allow for the existence of significant particle sources as well as sinks. Possible implications for radial diffusion mechanisms in the Uranian radiation belts are discussed.

  5. Elucidation of the Intestinal Absorption Mechanism of Celastrol Using the Caco-2 Cell Transwell Model.

    Science.gov (United States)

    Li, Hong; Li, Jie; Liu, Lu; Zhang, Yichuan; Luo, Yili; Zhang, Xiaoli; Yang, Peng; Zhang, Manna; Yu, Weifeng; Qu, Shen

    2016-08-01

    Celastrol, a triterpenoid isolated from stem (caulis) of Celastrus orbiculatus Thunb. (Celastraceae), has been known to have various pharmacological effects, including anti-inflammatory, anticancer, and antioxidant activities. However, the mechanism of the intestinal absorption of celastrol is unknown. The aim of this study was to investigate the intestinal absorption of celastrol using the Caco-2 cell transwell model. First, the bidirectional transport of celastrol in Caco-2 cell monolayers was observed. Then, the effects of time, concentration, temperature, paracellular pathway, and efflux transport inhibition on the transport of celastrol across the Caco-2 cell monolayers were investigated. The P-glycoprotein inhibitor verapamil and cyclosporin A, the multidrug resistance protein 2 inhibitor MK571, and the breast cancer resistance protein inhibitor reserpine were used. Additionally, the effects of celastrol on the activity of P-glycoprotein were evaluated using the rhodamine 123 uptake assay. In this study, we found that the intestinal transport of celastrol was a time- and concentration-dependent active transport. The paracellular pathway was not involved in the transport of celastrol, and the efflux of celastrol was energy dependent. The results indicated that celastrol is a substrate of P-glycoprotein but not multidrug resistance protein 2 or the breast cancer resistance protein. In addition, celastrol could not affect the uptake of rhodamine 123 in Caco-2 cells, which indicated that celastrol could not inhibit or induce the activity of P-glycoprotein. PMID:27159672

  6. Modeling the absorption spectra of Er3+ and Yb3+ in a phosphate glass

    Science.gov (United States)

    Gruber, John B.; Sardar, Dhiraj K.; Zandi, Bahram; Hutchinson, J. Andrew; Trussell, C. Ward

    2003-10-01

    Absorption spectra of Er3+ and Yb3+ ions, codopants in a phosphate glass, are reported at 8 K and at wavelengths between 350 and 1600 nm. Detailed structure appearing in the spectra, associated with individual multiplet states, 2S+1LJ, of Er3+(4f11) and Yb3+(4f13) is interpreted using a ligand-field coordination sphere model to characterize the microscopic environment surrounding the rare earth ions in multiple sites. Inhomogeneous broadening of the spectra is likely due to different configurations of PO4 tetrahedra clustered about a caged rare earth ion in the amorphous host. Similarity between the Er3+ spectrum in the glass and in the spectrum of single-crystal LiErP4O12, where Er3+ occupies sites of C2 symmetry, suggests that an averaged site symmetry of C2 is a reasonable approximation for Er3+ and Yb3+ ions in the phosphate glass. Calculated splitting of multiplet states by the ligand-field cluster model are compared with energy levels derived from the observed absorption peaks and well-defined shoulders. Inhomogeneous broadening of the spectra limit the precision in establishing the energy of the multiplet splittings, but the analysis is useful for modeling studies of the Er:Yb:phosphate glass as an eye-safe laser (1.53 μm). The splitting of the Yb3+(4f13)2FJ states is determined using parameters obtained from the Er3+ set by means of the three-parameter theory. No adjustments were made to the Yb3+ parameters that predict multiplet splittings in reasonable agreement with experimental data.

  7. Micro-Macro Scale Mixing Interactions by Intestinal Villi Enhance Absorption: a 3D Lattice-Boltzmann Model

    Science.gov (United States)

    Wang, Yanxing; Brasseur, James; Banco, Gino

    2010-11-01

    Muscle-induced villi motions may create a micro-scale flow that couples with a lumen-scale macro flow to enhance nutrient transport and absorption in the intestine. Using a 3D multiscale lattice Boltzmann model of a lid-driven cavity flow with microscale 3-D leaf and finger-like villi in pendular motion at the lower surface, we analyze the coupling between micro and macro-scale nutrient mixing and absorption at the villi surfaces. RESULTS: The villi motions enhance absorption by creating a micro-mixing layer (MML) that pumps low concentration fluid from between villi groups and attracts fluid with high concentration from the macro flow. The MML couples with the macro flow via a diffusion layer. Leaf-like villi create the strongest MML and, consequently, the highest absorption rates. The finger-like villi create a weaker MML due to the existence of flow between villi. The strength of the MML and nutrient absorption increases with villus frequency. The absorption rate also increases with villus length; however the simulations predict an optimal length close to the physiological length of villi in humans. The complex flow structure will be discussed. We conclude that the interaction between micro-scale villi-induced fluid motions and macro-scale motility-induced flow may play a significant role in intestinal absorption. Supported by NSF Grant CTS-056215.

  8. Made-to-measure galaxy modelling utilising absorption line strength data

    CERN Document Server

    Long, Richard

    2016-01-01

    We enhance the Syer & Tremaine made-to-measure (M2M) particle method of stellar dynamical modelling to model simultaneously both kinematic data and absorption line strength data thus creating a `chemo-M2M' modelling scheme. We apply the enhanced method to four galaxies (NGC 1248, NGC 3838, NGC 4452, NGC 4551) observed using the SAURON integral-field spectrograph as part of the ATLAS3D programme. We are able to reproduce successfully the 2D line strength data achieving mean chi^2 per bin values of ~1 with >95\\% of particles having converged weights. Because M2M uses a 3D particle system, we are also able to examine the underlying 3D line strength distributions. The extent to which these distributions are plausible representations of real galaxies requires further consideration. Overall we consider the modelling exercise to be a promising first step in developing a `chemo-M2M' modelling system and in understanding some of the issues to be addressed. Whilst the made-to-measure techniques developed have been ...

  9. Atmospheric absorption model for dry air and water vapor at microwave frequencies below 100 GHz derived from spaceborne radiometer observations

    Science.gov (United States)

    Wentz, Frank J.; Meissner, Thomas

    2016-05-01

    The Liebe and Rosenkranz atmospheric absorption models for dry air and water vapor below 100 GHz are refined based on an analysis of antenna temperature (TA) measurements taken by the Global Precipitation Measurement Microwave Imager (GMI) in the frequency range 10.7 to 89.0 GHz. The GMI TA measurements are compared to the TA predicted by a radiative transfer model (RTM), which incorporates both the atmospheric absorption model and a model for the emission and reflection from a rough-ocean surface. The inputs for the RTM are the geophysical retrievals of wind speed, columnar water vapor, and columnar cloud liquid water obtained from the satellite radiometer WindSat. The Liebe and Rosenkranz absorption models are adjusted to achieve consistency with the RTM. The vapor continuum is decreased by 3% to 10%, depending on vapor. To accomplish this, the foreign-broadening part is increased by 10%, and the self-broadening part is decreased by about 40% at the higher frequencies. In addition, the strength of the water vapor line is increased by 1%, and the shape of the line at low frequencies is modified. The dry air absorption is increased, with the increase being a maximum of 20% at the 89 GHz, the highest frequency considered here. The nonresonant oxygen absorption is increased by about 6%. In addition to the RTM comparisons, our results are supported by a comparison between columnar water vapor retrievals from 12 satellite microwave radiometers and GPS-retrieved water vapor values.

  10. Absorptive and dispersive optical profiles in fluctuating environments: A stochastic model

    International Nuclear Information System (INIS)

    In this study, we determined the absorptive and dispersive optical profiles of a molecular system coupled with a thermal bath. Solvent effects were explicitly considered by modelling the non-radiative interaction with the solute as a random variable. The optical stochastical Bloch equations (OSBE) were solved using a time-ordered cumulant expansion with white noise as a correlation function. We found a solution for the Fourier component of coherence at the third order of perturbation for the nonlinear Four-wave mixing signal and produced analytical expressions for the optical responses of the system. Finally, we examined the behaviour of these properties with respect to the noise parameter, frequency detuning of the dynamic perturbation, and relaxation times.

  11. Development of an in vitro model to simulate the gastrointestinal digestion and absorption of stabilizing agents

    Directory of Open Access Journals (Sweden)

    Uberti Francesca

    2014-01-01

    Full Text Available Each step in the winemaking process must be carefully planned and controlled to optimize the quality of wine. Among others, tartaric stabilization is a critical step in enology, and although effective, the usual practices to solve it show some qualitative limitations, and important economical and environmental impacts. For the reasons reported above, the wine producers are searching for alternative practices, with particular interest in the area of organic products. Biopolymers are possible alternatives in this field. The selection, the characterization and the safety aspects of new biopolymers are the objectives of the European project STABIWINE (Use of biopolymers for sustainable stabilization of quality wines. The first group of biopolymers analyzed includes polyaminoacids and, in particular, polymers of L-aspartic acid (PAA, which can be used as enological additives for tartaric stabilization. In order to contribute in drafting the toxicological dossier, the metabolic fate of PAAs has been assessed by in vitro models, mimicking gastrointestinal digestion and absorption.

  12. Adsorption of mercury on lignin: Combined surface complexation modeling and X-ray absorption spectroscopy studies

    International Nuclear Information System (INIS)

    Adsorption of mercury (Hg) on lignin was studied at a range of pH values using a combination of batch adsorption experiments, a surface complexation model (SCM) and synchrotron X-ray absorption spectroscopy (XAS). Surface complexation modeling indicates that three types of acid sites on lignin surfaces, namely aliphatic carboxylic-, aromatic carboxylic- and phenolic-type surface groups, contributed to Hg(II) adsorption. The bond distance and coordination number of Hg(II) adsorption samples at pH 3.0, 4.0 and 5.5 were obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy analysis. The results of SCM and XAS combined reveal that the predominant adsorption species of Hg(II) on lignin changes from HgCl20 to monodentate complex –C–O–HgCl and then bidentate complex –C–O–Hg–O–C– with increasing pH value from 2.0 to 6.0. The good agreement between SCM and XAS results provides new insight into understanding the mechanisms of Hg(II) adsorption on lignin. - Highlights: ► Lignin exhibits a high Hg(II) adsorption capability. ► Adsorption of Hg(II) on lignin is strongly pH-dependent. ► HgCl20, –C–O–HgCl and –C–O–Hg–O–C– are the main adsorption species of Hg(II). - Adsorption of Hg(II) on lignin is strongly pH-dependent, and the main adsorption Hg(II) species change from HgCl20 to –C–O–HgCl and –C–O–Hg–O–C– as pH increases from 2.0 to 6.0.

  13. Modelling and simulation of an absorption cycle with a blow pump; Modellierung und Simulation eines Absorptionskreislaufes mit einer Blasenpumpe

    Energy Technology Data Exchange (ETDEWEB)

    Buecherl, Markus

    2011-07-01

    Diffusion-absorption refrigerators are commonly operated with ammonia and water. If a ionic liquid with negligible vapour pressure is substituted for water, the rectifier will be unnecessary. In the context of a diploma thesis, a diffusion-absorption refrigerator with a blower pump and ammonia and a ionic liquid as working fluid was modelled and simulated. For this, three models were selected from the relevant literature and compared. Changes in COP as a result of varied operating parameters were investigated as well. It was shown that it is possible, in principle, to operate a diffusion-absorption refrigerator with a ionic liquid. [German] Diffusions-Absorptions-Kaeltemaschinen werden in der Regel mit dem Arbeitsstoffpaar Ammoniak-Wasser betrieben. Ersetzt man das Absorptionsmittel Wasser gegen eine ionische Fluessigkeit, die nur einen vernachlaessigbaren Dampfdruck besitzt, kann man den Rektifikator einsparen. Im Rahmen einer Diplomarbeit wurde eine Diffusions-Absorptions-Kaeltemaschine mit einer Blasenpumpe und dem Arbeitsstoffpaar Ammoniak-Ionische Fluessigkeit modelliert und simuliert. Hierfuer wurden drei Modelle aus der Literatur ausgewaehlt. Diese Modelle wurden untereinander verglichen. Ausserdem wurde die Veraenderung des COP bei der Variation der Betriebsparameter fuer diese Berechnungsmodelle untersucht. Es konnte gezeigt werden, dass es prinzipiell moeglich ist, eine Diffusions-Absorptions-Kaeltemaschine mit ionischer Fluessigkeit zu betreiben.

  14. Testing and optical modeling of novel concentrating solar receiver geometries to increase light trapping and effective solar absorptance

    Science.gov (United States)

    Yellowhair, Julius; Ho, Clifford K.; Ortega, Jesus D.; Christian, Joshua M.; Andraka, Charles E.

    2015-09-01

    Concentrating solar power receivers are comprised of panels of tubes arranged in a cylindrical or cubical shape on top of a tower. The tubes contain heat-transfer fluid that absorbs energy from the concentrated sunlight incident on the tubes. To increase the solar absorptance, black paint or a solar selective coating is applied to the surface of the tubes. However, these coatings degrade over time and must be reapplied, which reduces the system performance and increases costs. This paper presents an evaluation of novel receiver shapes and geometries that create a light-trapping effect, thereby increasing the effective solar absorptance and efficiency of the solar receiver. Several prototype shapes were fabricated from Inconel 718 and tested in Sandia's solar furnace at an irradiance of ~30 W/cm2. Photographic methods were used to capture the irradiance distribution on the receiver surfaces. The irradiance profiles were compared to results from raytracing models. The effective solar absorptance was also evaluated using the ray-tracing models. Results showed that relative to a flat plate, the new geometries could increase the effective solar absorptance from 86% to 92% for an intrinsic material absorptance of 86%, and from 60% to 73% for an intrinsic material absorptance of 60%.

  15. Multi-objective optimisation of a vehicle energy absorption structure based on surrogate model

    Institute of Scientific and Technical Information of China (English)

    谢素超; 周辉

    2014-01-01

    In order to optimize the crashworthy characteristic of energy-absorbing structures, the surrogate models of specific energy absorption (SEA) and ratio of SEA to initial peak force (REAF) with respect to the design parameters were respectively constructed based on surrogate model optimization methods (polynomial response surface method (PRSM) and Kriging method (KM)). Firstly, the sample data were prepared through the design of experiment (DOE). Then, the test data models were set up based on the theory of surrogate model, and the data samples were trained to obtain the response relationship between the SEA & REAF and design parameters. At last, the structure optimal parameters were obtained by visual analysis and genetic algorithm (GA). The results indicate that the KM, where the local interpolation method is used in Gauss correlation function, has the highest fitting accuracy and the structure optimal parameters are obtained as: the SEA of 29.8558 kJ/kg (corresponding toa=70 mm andt= 3.5 mm) and REAF of 0.2896 (corresponding toa=70 mm andt=1.9615 mm). The basis function of the quartic PRSM with higher order than that of the quadratic PRSM, and the mutual influence of the design variables are considered, so the fitting accuracy of the quartic PRSM is higher than that of the quadratic PRSM.

  16. Appraisal of Surface Hopping as a Tool for Modeling Condensed Phase Linear Absorption Spectra.

    Science.gov (United States)

    Petit, Andrew S; Subotnik, Joseph E

    2015-09-01

    Whereas surface hopping is usually used to study populations and mean-field dynamics to study coherences, in two recent papers, we described a procedure for calculating dipole-dipole correlation functions (and therefore absorption spectra) directly from ensembles of surface hopping trajectories. We previously applied this method to a handful of one-dimensional model problems intended to mimic the gas phase. In this article, we now benchmark this new procedure on a set of multidimensional model problems intended to mimic the condensed phase and compare our results against other standard semiclassical methods. By comparison, we demonstrate that methods that include only dynamical information from one PES (the standard Kubo approaches) exhibit large discrepancies with the results of exact quantum dynamics. Furthermore, for model problems with nonadiabatic excited state dynamics but no quantized vibrational structure in the spectra, our surface hopping approach performs comparably to using Ehrenfest dynamics to calculate the electronic coherences. That being said, however, when quantized vibrational structures are present in the spectra but the electronic states are uncoupled, performing the dynamics on the mean PES still outperforms our present method. These benchmark results should influence future studies that use ensembles of independent semiclassical trajectories to model linear as well as multidimensional spectra in the condensed phase. PMID:26575927

  17. Model of yield response of corn to plant population and absorption of solar energy.

    Directory of Open Access Journals (Sweden)

    Allen R Overman

    Full Text Available Biomass yield of agronomic crops is influenced by a number of factors, including crop species, soil type, applied nutrients, water availability, and plant population. This article is focused on dependence of biomass yield (Mg ha(-1 and g plant(-1 on plant population (plants m(-2. Analysis includes data from the literature for three independent studies with the warm-season annual corn (Zea mays L. grown in the United States. Data are analyzed with a simple exponential mathematical model which contains two parameters, viz. Y(m (Mg ha(-1 for maximum yield at high plant population and c (m(2 plant(-1 for the population response coefficient. This analysis leads to a new parameter called characteristic plant population, x(c = 1/c (plants m(-2. The model is shown to describe the data rather well for the three field studies. In one study measurements were made of solar radiation at different positions in the plant canopy. The coefficient of absorption of solar energy was assumed to be the same as c and provided a physical basis for the exponential model. The three studies showed no definitive peak in yield with plant population, but generally exhibited asymptotic approach to maximum yield with increased plant population. Values of x(c were very similar for the three field studies with the same crop species.

  18. An analytical model for the laser drilling of metals with absorption within the vapour

    Energy Technology Data Exchange (ETDEWEB)

    Solana, P. [Departamento de Matematica Aplicada, ETS Ingenieros Industriales, UPM, Madrid (Spain); Kapadia, P. [Department of Physics, University of Essex, Colchester (United Kingdom); Dowden, J.M. [Department of Mathematics, University of Essex, Colchester (United Kingdom); Marsden, P.J. [Sowerby Research Centre, British Aerospace, Filton, Bristol (United Kingdom)

    1999-04-21

    A mathematical model for the laser drilling of metals is given for the cases of constant and pulsed laser sources. Attenuation of the laser beam within the vapour is considered through an averaged absorption coefficient {alpha}. The experimentally observed logarithmic dependence of the hole depth on the laser energy is predicted theoretically. A singular perturbation technique is used in order to find solutions valid for different regimes of time, namely pre-vaporization and post-vaporization times. Uniformly valid solutions are found for the one-dimensional analysis of the drilling-front position and speed by matching the inner and outer solutions. First-order approximations for the time-dependent hole profile for the various laser source profiles considered are also found. The model is compared with experimental data in the literature for the drilling speed of copper. An additional set of experiments is specifically carried out to allow comparison with the theoretical hole profiles for titanium. The predictions of the model are found to agree well with the experiments. (author)

  19. Parameters for Modeling Aerosol Absorption: Measurements in Biomass Burning Smoke, Urban/Industrial Plumes, and NW Pacific Marine Airmasses

    Science.gov (United States)

    Kline, J. T.; Huebert, B. J.; Howell, S. G.; Uematsu, M.; Tsuruta, H.

    2003-12-01

    Absorbing aerosols such as elemental carbon (EC) play a large role in the Earth's radiation budget. However, the impact of EC emissions is hard to model accurately because the light absorption per mass of elemental carbon (EC specific absorption, ESA) varies with the source type and the conditions of the combustion that created it. The wavelength dependence of this absorption also varies with the size and nature of the absorbing material. We measured the ESA of ambient aerosol by measuring both light absorption at 7 wavelengths (as the reduction in light transmission through a quartz Aethalometer filter) and EC (by a thermal/chemical method) at Amami Ohshima, Japan as a part of the APEX program in the Spring of 2002. We also measured light scattering at 3 wavelengths so we could compute wavelength-dependent single-scatter albedos. We found that in smoke from sugar-cane burning the absorption varied as the inverse square of the wavelength, while in plumes from Asian mainland population centers it varied as the inverse of wavelength to the first power. We argue that models should therefore use different, wavelength-dependent "constants" for different conditions. Modelers also need to understand the degree to which the parameters they use depend on measurements that can contain large uncertainties.

  20. Modeling of carbon dioxide absorption by aqueous ammonia solutions using the Extended UNIQUAC model

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J. M.; Stenby, Erling Halfdan;

    2010-01-01

    An upgraded version of the Extended UNIQUAC thermodynamic model for the carbon dioxide-ammonia-water system has been developed, based on the original version proposed by Thomsen and Rasmussen. The original model was valid in the temperature range 0-110°C, the pressure range 0-10 MPa...... and the concentration range up to 80 molal ammonia. In this work, the validity of this model was extended up to 150°C and the accuracy improved by increasing the number of experimental data points from 2000 to more than 3500. These experimental data consisting of vapor-liquid equilibrium data in various concentration...... ranges, enthalpy change from partial evaporation measurements, speciation data, heat capacity, enthalpy of solution and enthalpy of dilution data have been used to refit 43 model parameters and standard state properties. Henry’s law constant correlations have been used for extrapolating standard state...

  1. Modelling the effect of oil/fat content in food systems on flavour absorption by LLDPE.

    NARCIS (Netherlands)

    Dekker, M.; Willige, van R.W.G.; Linssen, J.P.H.; Voragen, A.G.J.

    2003-01-01

    One of the phenomena in food packaging interactions is flavour absorption. Absorption of flavour compounds from food products into food-packaging materials can result in loss of flavour compounds or an unbalance in the flavour profile changing a product's quality. The food matrix influences the amou

  2. Identifying student and teacher difficulties in interpreting atomic spectra using a quantum model of emission and absorption of radiation

    Science.gov (United States)

    Savall-Alemany, Francisco; Domènech-Blanco, Josep Lluís; Guisasola, Jenaro; Martínez-Torregrosa, Joaquín

    2016-06-01

    Our study sets out to identify the difficulties that high school students, teachers, and university students encounter when trying to explain atomic spectra. To do so, we identify the key concepts that any quantum model for the emission and absorption of electromagnetic radiation must include to account for the gas spectra and we then design two questionnaires, one for teachers and the other for students. By analyzing the responses, we conclude that (i) teachers lack a quantum model for the emission and absorption of electromagnetic radiation capable of explaining the spectra, (ii) teachers and students share the same difficulties, and (iii) these difficulties concern the model of the atom, the model of radiation, and the model of the interaction between them.

  3. Identifying Student and Teacher Difficulties in Interpreting Atomic Spectra Using a Quantum Model of Emission and Absorption of Radiation

    Science.gov (United States)

    Savall-Alemany, Francisco; Domènech-Blanco, Josep Lluís; Guisasola, Jenaro; Martínez-Torregrosa, Joaquín

    2016-01-01

    Our study sets out to identify the difficulties that high school students, teachers, and university students encounter when trying to explain atomic spectra. To do so, we identify the key concepts that any quantum model for the emission and absorption of electromagnetic radiation must include to account for the gas spectra and we then design two…

  4. Mechanistic understanding of the effect of PPIs and acidic carbonated beverages on the oral absorption of itraconazole based on absorption modeling with appropriate in vitro data.

    Science.gov (United States)

    Fotaki, Nikoletta; Klein, Sandra

    2013-11-01

    Proton pump inhibitors (PPIs) are potent gastric acid suppressing agents and are among the most widely sold drugs in the world. However, even though these antisecretory agents are regarded as safe, they can alter the pharmacokinetics of coadministered drugs. Due to the suppression of gastric acid secretion, they can significantly alter the intragastric pH conditions and are thus likely to affect the bioavailability of coadministered drugs requiring an acidic gastric environment for dissolution and subsequent absorption. Among these drugs can be found itraconazole, a poorly soluble triazole-type antifungal compound. Based on observations reported in the literature, gastric pH alterations due to the coadministration of PPIs or acidic beverages can significantly decrease (PPI) or increase (e.g., Coca-Cola) the bioavailability of this compound. In the present work we estimated the fraction of itraconazole that can be absorbed (fabs) from Sporanox capsules or an itraconazole-HBenBCD complex formulation after oral administration with and without coadministration of a PPI or an acidic (carbonated) beverage. For this purpose, the sensitivity of the two formulations toward the impact of various gastric variations (pH, volume, and emptying rate) as they can result from such administration conditions was studied using solubility and dissolution experiments and a physiologically based absorption model. Simulating coadministration of the two formulations with a PPI resulted in a significant (∼ 10-fold) decrease in itraconazole fabs, indicating the pH to be essential for in vivo dissolution and subsequent absorption. The fabs of itraconazole after coadministration of an acidic beverage (Coca-Cola) was far lower than the fabs obtained for itraconazole alone and did not support the observations reported in the literature. These results clearly indicate that in contrast to PPIs, which seem to affect itraconazole bioavailability mainly via intragastric pH changes, coadministered

  5. Dermal absorption and skin damage following hydrofluoric acid exposure in an ex vivo human skin model.

    Science.gov (United States)

    Dennerlein, Kathrin; Kiesewetter, Franklin; Kilo, Sonja; Jäger, Thomas; Göen, Thomas; Korinth, Gintautas; Drexler, Hans

    2016-04-25

    The wide industrial use of hydrofluoric acid (HF) poses a high risk for accidental dermal exposure. Despite local and systemic hazards associated with HF, information on percutaneous penetration and tissue damage is rare. In the present ex vivo study, the dermal absorption of HF (detected in terms of fluoride ions) was quantified and the skin damaging potential as a function of concentration and exposure duration was assessed. Percutaneous penetration of HF (c=5, 30, and 50%) at 3 exposure durations (3, 5, and 10 min) was investigated in a static diffusion cell model using freshly excised human skin. Alterations of skin were histologically evaluated. HF rapidly penetrated through skin under formation of a considerable intradermal reservoir (∼ 13-67% of total absorbed fluoride). Histologically, epidermal alterations were detected already after exposure to 5% HF for 3 min. The degree of skin damage increased with rising concentration and exposure duration leading to coagulation necrosis. For HF concentrations of ≥ 30%, skin damage progressed into deeper skin layers. Topically applied HF concentration was the principal parameter determining HF induced skin effects. The intradermal HF retention capacity associated with progression and prolongation of HF induced skin effects must be considered in the review of skin decontamination procedures.

  6. Modeling and Control of a Double-effect Absorption Refrigerating Machine

    Science.gov (United States)

    Hihara, Eiji; Yamamoto, Yuuji; Saito, Takamoto; Nagaoka, Yoshikazu; Nishiyama, Noriyuki

    For the purpose of impoving the response to cooling load variations and the part load characteristics, the optimal operation of a double-effect absorption refrigerating machine was investigated. The test machine was designed to be able to control energy input and weak solution flow rate continuously. It is composed of a gas-fired high-temperature generator, a separator, a low-temperature generator, an absorber, a condenser, an evaporator, and high- and low-temperature heat exchangers. The working fluid is Lithium Bromide and water solution. The standard output is 80 kW. Based on the experimental data, a simulation model of the static characteristics was developed. The experiments and simulation analysis indicate that there is an optimal weak solution flow rate which maximizes the coefficient of performance under any given cooling load condition. The optimal condition is closely related to the refrigerant steam flow rate flowing from the separator to the high temperature heat exchanger with the medium solution. The heat transfer performance of heat exchangers in the components influences the COP. The change in the overall heat transfer coefficient of absorber has much effect on the COP compared to other components.

  7. Extended UNIQUAC model for thermodynamic modeling of CO2 absorption in aqueous alkanolamine solutions

    DEFF Research Database (Denmark)

    Faramarzi, Leila; Kontogeorgis, Georgios; Thomsen, Kaj;

    2009-01-01

    and they cover a very wide range of conditions. Vapor-liquid equilibrium (VLE) data for the aqueous alkanolamine systems containing CO2 in the pressure range of 3-13,000 kPa and temperatures of 25-200 C are used. The model is also regressed with the VLE and freezing point depression data of the binary aqueous...... alkanolamine systems (MEA-water and MDEA-water). The two just mentioned types of data cover the full concentration range of alkanolamines from extremely dilute to almost pure. The experimental freezing point depression data down to the temperature of -20 degrees C are used. Experimental excess enthalpy (H......) are included in the parameter estimation process. The previously unavailable standard state properties of the alkanolamine ions appearing in this work, i.e. MEA protonate, MEA carbamate and MDEA protonate are determined. The concentration of the species in both MEA and MDEA solutions containing CO2...

  8. Absorber Models for absorption of Carbon dioxide from sour natural gas byMethyl-diethanol Amine (MDEA

    Directory of Open Access Journals (Sweden)

    Akpa

    2014-12-01

    Full Text Available Mathematical models of the absorber for the absorption of carbon dioxide (CO2from sour natural gas in Methyl-diethanol Amine (MDEAsolution were developed. The resulting ordinary differential model equations were solved numerically using theode45 solver of MATLAB 7.5. The accuracy of the models was ascertained using industrial plant data from the carbon dioxide absorber of the Obiafu/Obrikom Gas Treatment plant in Rivers State, Nigeria. The models predicted the CO2 concentration in the sweet gas, gas and solvent (MDEA temperature progressions along the packed absorber. The results obtained from solutions to the models compared favorably with the plant outputs with a maximum deviation between models predictions and industrial plant outputs of 0.44%. The models were used to simulate the influence of sour gas flow rates and solvent (MDEA concentration in solution on the performance (absorption rates of CO2 of the absorber.The results show that the absorption rate of CO2 increases with increasing gas flow rate and solvent concentration.

  9. Absorption of manganese and iron in a mouse model of hemochromatosis.

    Directory of Open Access Journals (Sweden)

    Jonghan Kim

    Full Text Available Hereditary hemochromatosis, an iron overload disease associated with excessive intestinal iron absorption, is commonly caused by loss of HFE gene function. Both iron and manganese absorption are regulated by iron status, but the relationships between the transport pathways of these metals and how they are affected by HFE-associated hemochromatosis remain poorly understood. Loss of HFE function is known to alter the intestinal expression of DMT1 (divalent metal transporter-1 and Fpn (ferroportin, transporters that have been implicated in absorption of both iron and manganese. Although the influence of HFE deficiency on dietary iron absorption has been characterized, potential effects on manganese metabolism have yet to be explored. To investigate the role of HFE in manganese absorption, we characterized the uptake and distribution of the metal in Hfe (-/- knockout mice after intravenous, intragastric, and intranasal administration of (54Mn. These values were compared to intravenous and intragastric administration of (59Fe. Intestinal absorption of (59Fe was increased and clearance of injected (59Fe was also increased in Hfe(-/- mice compared to controls. Hfe (-/- mice displayed greater intestinal absorption of (54Mn compared to wild-type Hfe(+/+ control mice. After intravenous injection, the distribution of (59Fe to heart and liver was greater in Hfe (-/- mice but no remarkable differences were observed for (54Mn. Although olfactory absorption of (54Mn into blood was unchanged in Hfe (-/- mice, higher levels of intranasally-instilled (54Mn were associated with Hfe(-/- brain compared to controls. These results show that manganese transport and metabolism can be modified by HFE deficiency.

  10. Non-Fickian three-dimensional moisture absorption in polymeric composites: Development and validation of hindered diffusion model

    Science.gov (United States)

    Grace, Landon

    The importance of environmental damage consideration in the design of polymeric composite structures is discussed, with emphasis on the relationship between absorbed moisture content and material property degradation. A brief overview of existing predictive models of moisture diffusion and their limitations is presented. The three-dimensional anisotropic Fickian diffusion model is expanded to include the effects of the interaction of diffusing molecules with the chemical and physical structure of polymeric composites. The numerical solution of this novel hindered diffusion model is obtained for a three-dimensional, anisotropic domain by using a forward-time centered-space finite difference technique. The numerical solution method is verified by comparing the results to known analytical solutions of a one-dimensional, "Langmuir-type" diffusion model and for the limiting case of the three-dimensional Fickian model. The proposed three-dimensional anisotropic hindered diffusion model (3D HDM) and its one-dimensional isotropic version are successfully applied to three experimental moisture absorption data sets reconstructed from existing literature. An analytical solution based on a judicious approximation to the 3D HDM is developed in an effort to increase the utility of the model in the recovery of polymeric composite diffusion properties from experimental data. The effectiveness of the recovery of absorption properties is assessed using artificially generated "synthetic" experimental data. The anisotropic diffusivities, equilibrium moisture content (Minfinity), and molecular binding (gamma) and unbinding (beta) probabilities that govern three-dimensional hindered diffusion are recovered using least-squares regression. Using both Fickian and non-Fickian synthetic moisture absorption data, diffusivities and equilibrium moisture content are recovered with less than 1% error. Values of gamma and beta are recovered with less than 3% error in the non-Fickian diffusion case

  11. Incorporating a Generic Model of Subcutaneous Insulin Absorption into the AIDA v4 Diabetes Simulator 3. Early Plasma Insulin Determinations

    Science.gov (United States)

    Lehmann, Eldon D.; Tarín, Cristina; Bondia, Jorge; Teufel, Edgar; Deutsch, Tibor

    2009-01-01

    Introduction AIDA is an interactive educational diabetes simulator that has been available without charge via the Internet for over 12 years. Recent articles have described the incorporation of a novel generic model of insulin absorption into AIDA as a way of enhancing its capabilities. The basic model components to be integrated have been overviewed, with the aim being to provide simulations of regimens utilizing insulin analogues, as well as insulin doses greater than 40 IU (the current upper limit within the latest release of AIDA [v4.3a]). Some preliminary calculated insulin absorption results have also recently been described. Methods This article presents the first simulated plasma insulin profiles from the integration of the generic subcutaneous insulin absorption model, and the currently implemented model in AIDA for insulin disposition. Insulin absorption has been described by the physiologically based model of Tarín and colleagues. A single compartment modeling approach has been used to specify how absorbed insulin is distributed in, and eliminated from, the human body. To enable a numerical solution of the absorption model, a spherical subcutaneous depot for the injected insulin dose has been assumed and spatially discretized into shell compartments with homogeneous concentrations, having as its center the injection site. The number of these compartments will depend on the dose and type of insulin. Insulin inflow arises as the sum of contributions to the different shells. For this report the first bench testing of plasma insulin determinations has been done. Results Simulated plasma insulin profiles are provided for currently available insulin preparations, including a rapidly acting insulin analogue (e.g., lispro/Humalog or aspart/Novolog), a short-acting (regular) insulin preparation (e.g., Actrapid), intermediate-acting insulins (both Semilente and neutral protamine Hagedorn types), and a very long-acting insulin analogue (e.g., glargine/Lantus), as

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

    Science.gov (United States)

    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.

  13. Elevated CSF outflow resistance associated with impaired lymphatic CSF absorption in a rat model of kaolin-induced communicating hydrocephalus

    Directory of Open Access Journals (Sweden)

    Li Jie

    2010-02-01

    Full Text Available Abstract Background We recently reported a lymphatic cerebrospinal fluid (CSF absorption deficit in a kaolin model of communicating hydrocephalus in rats with ventricular expansion correlating negatively with the magnitude of the impediment to lymphatic function. However, it is possible that CSF drainage was not significantly altered if absorption at other sites compensated for the lymphatic defect. The purpose of this study was to investigate the impact of the lymphatic absorption deficit on global CSF absorption (CSF outflow resistance. Methods Kaolin was injected into the basal cisterns of Sprague Dawley rats. The development of hydrocephalus was assessed using magnetic resonance imaging (MRI. In one group of animals at about 3 weeks after injection, the movement of intraventricularly injected iodinated human serum albumin (125I-HSA into the olfactory turbinates provided an estimate of CSF transport through the cribriform plate into nasal lymphatics (n = 18. Control animals received saline in place of kaolin (n = 10. In a second group at about 3.5 weeks after kaolin injection, intraventricular pressure was measured continuously during infusion of saline into the spinal subarachnoid space at various flow rates (n = 9. CSF outflow resistance was calculated as the slope of the steady-state pressure versus flow rate. Control animals for this group either received no injections (intact: n = 11 or received saline in place of kaolin (n = 8. Results Compared to saline injected controls, lateral ventricular volume in the kaolin group was significantly greater (0.087 ± 0.013 ml, n = 27 versus 0.015 ± 0.001 ml, n = 17 and lymphatic function was significantly less (2.14 ± 0.72% injected/g, n = 18 versus 6.38 ± 0.60% injected/g, n = 10. Additionally, the CSF outflow resistance was significantly greater in the kaolin group (0.46 ± 0.04 cm H2O.μL-1.min, n = 9 than in saline injected (0.28 ± 0.03 cm H2O.μL-1.min, n = 8 or intact animals (0.18 ± 0

  14. Experimental evidence and theoretical modeling of two-photon absorption dynamics in the reduction of intensity noise of solid-state Er:Yb lasers.

    Science.gov (United States)

    El Amili, Abdelkrim; Kervella, Gaël; Alouini, Mehdi

    2013-04-01

    A theoretical and experimental investigation of the intensity noise reduction induced by two-photon absorption in a Er,Yb:Glass laser is reported. The time response of the two-photon absorption mechanism is shown to play an important role on the behavior of the intensity noise spectrum of the laser. A model including an additional rate equation for the two-photon-absorption losses is developed and allows the experimental observations to be predicted.

  15. Assessment of In Vivo Clinical Product Performance of a Weak Basic Drug by Integration of In Vitro Dissolution Tests and Physiologically Based Absorption Modeling.

    Science.gov (United States)

    Ding, Xuan; Gueorguieva, Ivelina; Wesley, James A; Burns, Lee J; Coutant, Carrie A

    2015-11-01

    Effective integration of in vitro tests and absorption modeling can greatly improve our capability in understanding, comparing, and predicting in vivo performances of clinical drug products. In this case, we used a proprietary drug candidate galunisertib to describe the procedures of designing key in vitro tests, analyzing relevant experimental and trial data, and integrating them into physiologically based absorption models to evaluate the performances of its clinical products. By simulating the preclinical study result, we estimated high in vivo permeability for the drug. Given the high sensitivity of its solubility to pH, supersaturation may play an important role in the absorption of galunisertib. Using the dynamic dissolution test, i.e., artificial stomach-duodenum (ASD) model and simulation, we concluded galunisertib in solution or tablet products could maintain supersaturation during the transit in the gastrointestinal tract (GIT). A physiologically based absorption model was established by incorporating these key inputs in the simulation of Trial 1 results of galunisertib solution. To predict the performance of three tablet products, we developed z-factor dissolution models from the multi-pH USP dissolution results and integrate them into the absorption model. The resultant biopharmaceutical models provided good prediction of the extent of absorption of all three products, but underestimated the rate of absorption of one tablet product. Leveraging the ASD result and optimization with the dissolution model, we identified the limitation of the model due to complexity of estimating the dissolution parameter z and its in vitro-in vivo correlation. PMID:26126932

  16. Modelling LiBr-H2O solution concentration/crystallization of low thermal-powered absorption air conditioning system

    International Nuclear Information System (INIS)

    A computer model is developed to predict the concentration of lithium bromide - water (LiBr-H2O) solution for used in low thermal energy-driven absorption air conditioning plants design. The computer program is capable to alert the users from undesirable solidification or crystallization zones. Good agreements between simulated concentration and experimental data from standard chart/table have been obtained. (Author)

  17. Dietary inulin supplementation does not promote colonic iron absorption in a porcine model

    Science.gov (United States)

    Prebiotics may enhance iron bioavailability by increasing iron absorption in the colon. Anemic pigs fitted with cecal cannulas were fed a low-iron diet with or without 4% inulin. Over 7 days, pigs were administered 1 mg 54 Fe in the morning feed followed by cannula infusion of 0.5 mg 58 Fe to measu...

  18. Feasibility of a 3D human airway epithelial model to study respiratory absorption

    NARCIS (Netherlands)

    Reus, A.A.; Maas, W.J.M.; Jansen, H.T.; Constant, S.; Staal, Y.C.M.; Triel, J.J. van; Kuper, C.F.

    2014-01-01

    The respiratory route is an important portal for human exposure to a large variety of substances. Consequently, there is an urgent need for realistic in vitro strategies for evaluation of the absorption of airborne substances with regard to safety and efficacy assessment. The present study investiga

  19. The average ion model. Computation of the absorption and emission coefficients in hot plasmas

    Science.gov (United States)

    Gauthier, Jean-Claude; Geindre, Jean-Paul

    1988-06-01

    A program was developed to evaluate the emission and absorption plasma coefficient variations as a function of the density, temperature and the atomic number of the specimen. The treatment is simplified because of the reduced number of characteristic frequencies which are necessary for the hydrodynamic code. The approach is less efficient when applied to high Z atoms.

  20. An improved model for studies on transdermal drug absorption invivo in rats

    NARCIS (Netherlands)

    VOLLMER, U; MULLER, BW; WILFFERT, B; Peters, Thies

    1993-01-01

    In rats, transdermal drug absorption can be studied under physiological conditions by cannulating the peripheral skin vein, draining the area of the skin which is used for drug application, and collecting the blood. This method leads to decreased blood volume, which causes a reduction in skin blood

  1. An improved model for studies on transdermal drug absorption in-vivo in rats

    NARCIS (Netherlands)

    Vollmer, U.; Muller, B.W.; Wilffert, B.; Peters, Thies

    1993-01-01

    In rats, transdermal drug absorption can be studied under physiological conditions cannulating the peripheral skin vein, draining the area of the skin which is used for drug application, and collecting the blood. This method leads to decreased blood volume, which causes a reduction in skin blood flo

  2. Infrared absorption line intensities for U (5) model of linear triatomic molecules

    Institute of Scientific and Technical Information of China (English)

    于少英

    1999-01-01

    The symmetry of the rotation-vibration spectra for linear triatomic molecules is described by means of the group U(5). The rotation-vibration levels of linear triatomic molecules HCN and COS are calculated. The infrared absorption line intensities are calculated for the COS molecule. The results are in good agreement with the experimental values.

  3. Study of Electromagnetic Radiation and Specific Absorption Rate of Mobile Phones with Fractional Human Head Models via Green's Functions

    Directory of Open Access Journals (Sweden)

    Nookala S. Rao

    2011-01-01

    Full Text Available Problem statement: Electromagnetic Radiation from mobile hand set is identified as one of the side effects for increasing rate of brain tumor. Due to this reason, Mobile phone industries are attentive towards safety issues of human health. Specific Absorption Rate is one of the important parameter while modeling the radiation effect on human head. Brain material with homogeneity is treated as an equivalent model of human head. The radiation caused by antennas mounted on mobile set is assumed to be monopolar. Approach: Apart from the Specific Absorption Rate, period of exposure to radiation is an extremely important parameter while assessing the effects on brain tissue. Correlation between the amount of radiation versus spherical model of brain is a complex phenomena, addressed in various simulation models. In the present work the field distribution inside the head are modeled using Dyadic Greens Functions while describing the effect of radiation pattern. Multilayered homogeneous lossy spherical model is proposed as an equivalent to head. Results: In this paper we present the depth of penetration of radiation and its effect on brain tissue. In essence the amount of electromagnetic power absorbed by biological tissues for various exposure conditions and types of emitting sources, utilizing a detailed model of the human head. Conclusion: Bio-heat equation is used to predict heat distribution inside the brain when exposed to radiation. The medium is assumed to be homogeneous, isotropic, linear, non dispersive and stationary. A critical evaluation of the method is discussed.

  4. Verification of a two-layer inverse Monte Carlo absorption model using multiple source-detector separation diffuse reflectance spectroscopy.

    Science.gov (United States)

    Sharma, Manu; Hennessy, Ricky; Markey, Mia K; Tunnell, James W

    2013-12-01

    A two-layer Monte Carlo lookup table-based inverse model is validated with two-layered phantoms across physiologically relevant optical property ranges. Reflectance data for source-detector separations of 370 μm and 740 μm were collected from these two-layered phantoms and top layer thickness, reduced scattering coefficient and the top and bottom layer absorption coefficients were extracted using the inverse model and compared to the known values. The results of the phantom verification show that this method is able to accurately extract top layer thickness and scattering when the top layer thickness ranges from 0 to 550 μm. In this range, top layer thicknesses were measured with an average error of 10% and the reduced scattering coefficient was measured with an average error of 15%. The accuracy of top and bottom layer absorption coefficient measurements was found to be highly dependent on top layer thickness, which agrees with physical expectation; however, within appropriate thickness ranges, the error for absorption properties varies from 12-25%. PMID:24466475

  5. Thermodynamic modelling and kinetics of hydrogen absorption associated with phase transformations; Modelisation thermodynamique et cinetiques d'absorption de l'hydrogene associees aux transformations de phase

    Energy Technology Data Exchange (ETDEWEB)

    Gondor, G.; Lexcellent, Ch. [LMARC FEMTO-ST, 25 - Besancon (France)

    2007-07-01

    The intermetallic are used for hydrogen pressure containers in order to avoid leaks in the case of an hybrid container. The hydrogen atoms are absorbed by the intermetallic which act as a hydrogen sponge. This hydrogen absorption must be modelled for the container design. The Pressure-composition isotherms describe the equilibrium. Out of this equilibrium the kinetics are controlled by different processes, without taking into account the phase transformations. The author presents a new model of the p-c isotherms with the hydrogen absorption kinetics. (A.L.B.)

  6. Testing Disk-Wind Models with Quasar CIV 1549Å Associated Absorption Lines

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2012-01-01

    Narrow associated C IV 1549Å absorption lines (NALs) with a rest equivalent width EW =3 Å detected in z ˜ 2 radio-loud and radio-quiet quasars, (a) exhibit evidence of an origin in radiatively accelerated gas, and (b) may be closely related to broad absorption line (BAL) outflows. These NALs......-ray to UV emission ratio, i.e., aOX. The latter means that quasars with flat aOX (like radio-louds) should not have strong, high-velocity (BAL-like) outflows. These results are of interest not only to studies of disk wind scenarios and quasar structure, but also to studies of quasar feedback: NALs...

  7. Computing the Absorption and Emission Spectra of 5-Methylcytidine in Different Solvents: A Test-Case for Different Solvation Models.

    Science.gov (United States)

    Martínez-Fernández, L; Pepino, A J; Segarra-Martí, J; Banyasz, A; Garavelli, M; Improta, R

    2016-09-13

    The optical spectra of 5-methylcytidine in three different solvents (tetrahydrofuran, acetonitrile, and water) is measured, showing that both the absorption and the emission maximum in water are significantly blue-shifted (0.08 eV). The absorption spectra are simulated based on CAM-B3LYP/TD-DFT calculations but including solvent effects with three different approaches: (i) a hybrid implicit/explicit full quantum mechanical approach, (ii) a mixed QM/MM static approach, and (iii) a QM/MM method exploiting the structures issuing from molecular dynamics classical simulations. Ab-initio Molecular dynamics simulations based on CAM-B3LYP functionals have also been performed. The adopted approaches all reproduce the main features of the experimental spectra, giving insights on the chemical-physical effects responsible for the solvent shifts in the spectra of 5-methylcytidine and providing the basis for discussing advantages and limitations of the adopted solvation models. PMID:27529792

  8. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    Science.gov (United States)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  9. Intestinal absorption of forsythoside A in in situ single-pass intestinal perfusion and in vitro Caco-2 cell models

    Institute of Scientific and Technical Information of China (English)

    Wei ZHOU; Liu-qing DI; Juan WANG; Jin-jun SHAN; Shi-jia LIU; Wen-zheng JU; Bao-chang CAI

    2012-01-01

    Aim:To investigate the mechanisms underlying the intestinal absorption of the major bioactive component forsythoside A (FTA) extracted from Forsythiae fructus.Methods:An in vitro Caco-2 cell model and a single-pass intestinal perfusion in situ model in SD rats were used.Results:In the in vitro Caco-2 cell model,the mean apparent permeability value (Papp-value) was 4.15x 107 cm/s in the apical-tobasolateral (AP-BL) direction.At the concentrations of 2.6-10.4 μg/mL,the efflux ratio of FTA in the bi-directional transport experiments was approximately 1.00.After the transport,>96% of the apically loaded FTA was retained on the apical side,while >97% of the basolaterally loaded FTA was retained on the basolateral side.The Papp-values of FTA were inversely correlated with the transepithelial electrical resistance.The paracellular permeability enhancers sodium caprate and EDTA,the P-gp inhibitor verapamil and the multidrug resistance related protein (MRP) inhibitors cyclosporine and MK571 could concentration-dependently increase the Papp-values,while the uptake (OATP) transporter inhibitors diclofenac sodium and indomethacin could concentration-dependently decrease the Papp-values.The intake transporter SGLT1 inhibitor mannitol did not cause significant change in the Papp-values.In the in situ intestinal perfusion model,both the absorption rate constant (Ka) and the effective permeability (Peff-values) following perfusion of FTA 2.6,5.2,and 10.4 μg/mL via the duodenum,jejunum and ileum had no significant difference,although the values were slightly higher for the duodenum as compared to those in the jejunum and ileum.The low,medium and high concentrations of verapamil caused the largest increase in the Peff-values for duodenum,jejunum and ileum,respectively.Sodium caprate,EDTA and cyclosporine resulted in concentration-dependent increase in the Peff-values.Diclofenac sodium and indomethacin caused concentration-dependent decrease in the Peff-values.Mannitol did

  10. Gas desulfurization with ferric chelates of EDTA and HEDTA: New model for the oxidative absorption of hydrogen sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Demmink, J.F.; Beenackers, A.A.C.M. [Univ. of Groningen (Netherlands). Dept. of Chemical Engineering

    1998-04-01

    The experimental data of Wubs and Beenackers on the oxidative absorption of H{sub 2}S into aqueous solutions of ferric chelates of ethylenediaminetetraacetic acid (EDTA) and hydroxyethylethylenediaminetriactic (HEDTA) were reinterpreted using a new penetration model for mass transfer parallel to chemical reaction. Different from the discussion by Wubs and Beenackers (1994), which was based on general, approximate models for the reactive absorption of gases into liquids, it now appears that the diffusivity of ferric chelates of EDTA and HEDTA are in good agreement with the values determined from the reactive absorption of molecular oxygen into aqueous solutions of ferrous EDTA and HEDTA. Also, it now appears that the data from Wubs and Beenackers (1994) are compatible with ferric chelate complex equilibrium constants, reported elsewhere. Reinterpretation of the absorption data from Wubs and Beenackers (1994) resulted in the following kinetic rate constants (T = 293 K, C{sub Fe(III)} = 78 mol/m{sup 3} and 2 {le} pH {le} 9): EDTA, monohydroxylated complex, 250 {le} k{sub 1.1} {le} 300 m{sup 3}/(mol s); HEDTA, monohydroxylated complex, 1.4 {le} k{sub 1.1} {le} 1.6 m{sup 3}/(mol s); HEDTA, dihydroxylated complex, 550 {le} k{sub 1.1} {le} 650 m{sup 3}/(mol s); for the reaction rate expressed by {minus}R{sub H{sub 2}S} = k{sub 1.1}C{sub h{sub 2}S}C{sub Fe(III)}.

  11. Simultaneous Pharmacokinetic Modeling of Alkylresorcinols and Their Main Metabolites Indicates Dual Absorption Mechanisms and Enterohepatic Elimination in Humans

    DEFF Research Database (Denmark)

    Marklund, Matti; Strömberg, Eric A,; Lærke, Helle Nygaard;

    2014-01-01

    was to develop a combined pharmacokinetic model for plasma concentrations of alkylresorcinols and their 2 major metabolites, 3,5-dihydroxybenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-propanoic acid (DHPPA).Methods: The model was established by using plasma samples collected from 3 women and 2 men after...... ileostomal effluent and pig bile after high and low alkylresorcinol doses were analyzed to evaluate biliary alkylresorcinol metabolite excretion.Results: The model contained 2 absorption compartments: 1 that transferred alkylresorcinols directly to the systematic circulation and 1 in which a proportion......), and DHBA (1.3 ± 0.22 h) did not differ. The model accurately predicted alkylresorcinol and DHBA concentrations after repeated alkylresorcinol intake but DHPPA concentration was overpredicted, possibly because of poorly modeled enterohepatic circulation. During the 8 h following administration,

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

    Energy Technology Data Exchange (ETDEWEB)

    Sandrini, L; Vaccari, A; Malacarne, C; Cristoforetti, L; Pontalti, R [ITC-irst-Bioelectromagnetism Lab., FCS Department, 38050 Povo (Trento) (Italy)

    2004-11-21

    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.

  13. Modeling IR Spectral Energy Distributions: A Pilot Study of Starburst Parameters and Silicate Absorption Curves for Some GOALS Galaxies

    CERN Document Server

    Dopita, Michael A; Kewley, Lisa J; Rich, Jeff A; Sanders, Dave; Appleton, Phillip N; Chan, Ben H P; Charmandaris, Vassilis; Evans, Aaron S; Frayer, David T; Howell, Justin H; Inami, Hanae; Mazzarella, Joseph A; Petric, Andreea; Stierwalt, Sabrina; Surace, Jason

    2010-01-01

    This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the \\emph{Spitzer Space Telescope}. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine `astronomical silicate' model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished ($A_{\\rm V} \\sim 50$mag.) starbursts. We have derived an empirical fit to the `starburst silicate' absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AG...

  14. Absorption of plant lignans from cereals in an experimental pig model.

    Science.gov (United States)

    Bolvig, Anne Katrine; Adlercreutz, Herman; Theil, Peter Kappel; Jørgensen, Henry; Bach Knudsen, Knud Erik

    2016-05-28

    Plant lignans are diphenolic compounds ingested with whole grains and seeds and converted to enterolignans by the colonic microbiota. In the present study, we investigated absorption and metabolism of plant lignans and enterolignans in vivo after consumption of cereal-based diets. Six pigs fitted with catheters in the mesenteric artery and portal vein and with a flow probe attached to the portal vein along with twenty pigs for quantitative collection of urine were used for this study. The animals were fed bread based on wheat flour low in plant lignans and three lignan-rich breads based on whole-wheat grain, wheat aleurone flour or rye aleurone flour. Plant lignans and enterolignans in plasma were monitored daily at fast after 0-3 d of lignan-rich intake, and on the 4th day of lignan-rich intake a 10-h profile was completed. Urine samples were collected after 11 d of lignan-rich diet consumption. The concentrations of plant lignans were low at fast, and was 1·2-2·6 nmol/l after switching from the low-lignan diet to the lignan-rich diets. However, on the profile day, the concentration and quantitative absorption of plant lignans increased significantly from 33 nmol/h at fast to 310 nmol/h 0-2·5 h after ingestion with a gradual increase in the following periods. Quantitatively, the absorption of plant lignans across diets amounted to 7 % of ingested plant lignans, whereas the urinary excretion of plant lignans was 3 % across diets. In conclusion, there is a substantial postprandial uptake of plant lignans from cereals, suggesting that plant lignans are absorbed from the small intestine.

  15. Treatment of overlapping gaseous absorption with the correlated-k method in hot Jupiter and brown dwarf atmosphere models

    CERN Document Server

    Amundsen, David S; Manners, James; Baraffe, Isabelle; Mayne, Nathan J

    2016-01-01

    The correlated-k method is frequently used to speed up radiation calculations in both one-dimensional and three-dimensional atmosphere models. An inherent difficulty with this method is how to treat overlapping absorption, i.e. absorption by more than one gas in a given spectral region. We have evaluated the applicability of three different methods in hot Jupiter and brown dwarf atmosphere models, all of which have been previously applied within models in the literature: (i) Random overlap, both with and without resorting and rebinning, (ii) equivalent extinction and (iii) pre-mixing of opacities, where (i) and (ii) combine k-coefficients for different gases to obtain k-coefficients for a mixture of gases, while (iii) calculates k-coefficients for a given mixture from the corresponding mixed line-by-line opacities. We find that the random overlap method is the most accurate and flexible of these treatments, and is fast enough to be used in one-dimensional models with resorting and rebinning. In three-dimensio...

  16. A new analysis of fine-structure constant measurements and modelling errors from quasar absorption lines

    OpenAIRE

    Wilczynska, Michael R.; Webb, John K.; King, Julian A.; Murphy, Michael T.; Bainbridge, Matthew B.; Flambaum, Victor V.

    2015-01-01

    We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of $0.4 \\leq z_{abs} \\leq 2.3$ observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Considering both statistical and systematic error contributions we find a robust estimate of the weighted mean deviation of the fine-structure constant from its current, laboratory value of $\\Delta\\alpha/\\alpha=\\left(0.22\\pm0.23\\right)\\times10^{-5...

  17. Crashworthiness and composite materials: development of an experimental test method for the energy absorption determination and implementation of the relative numerical model

    OpenAIRE

    Garattoni, Francesca

    2011-01-01

    In this PhD thesis the crashworthiness topic is studied with the perspective of the development of a small-scale experimental test able to characterize a material in terms of energy absorption. The material properties obtained are then used to validate a nu- merical model of the experimental test itself. Consequently, the numerical model, calibrated on the specific ma- terial, can be extended to more complex structures and used to simulate their energy absorption behavior. The experimental...

  18. Measurement of Silver Nanolayer Absorption by the Body in an in Vivo Model of Inflammatory Gastrointestinal Diseases

    Directory of Open Access Journals (Sweden)

    Siczek Krzysztof

    2016-03-01

    Full Text Available Layers of silver particles are used in the studies on pathophysiology and treatment of diseases, both in pre-clinical and clinical conditions. Silver layers can be formed using different techniques and on different substrates. Deposition by magnetron sputtering on glass beads was used in this study. Silver absorption by the body was estimated by calculating the difference in thickness of the silver nanolayer deposited on a bead and measured before and after application of the bead in an animal model of gastrointestinal inflammation. Recommendations for the minimal thickness of silver nanolayer deposited on glass beads were worked out for further studies.

  19. Strong absorption model analysis of elastic K sup + scatterings on nuclei and a potential calculation by inversion

    CERN Document Server

    Kim, Y J

    1999-01-01

    We analyze the elastic scattering of 800 MeV/c positive kaons from sup 1 sup 2 C and sup 4 sup 0 Ca nuclei within the framework of the McIntyre strong absorption model. The calculated differential cross-sections are found to be in excellent agreement with the observed data. Near- and far-side decompositions of the elastic cross-section have also been performed by following Fuller's formalism. The corresponding complex potentials are predicted by using the inversion procedure of the McIntyre S-matrix.

  20. PHOTOIONIZATION MODELING OF OXYGEN K ABSORPTION IN THE INTERSTELLAR MEDIUM: THE CHANDRA GRATING SPECTRA OF XTE J1817-330

    Energy Technology Data Exchange (ETDEWEB)

    Gatuzz, E.; Mendoza, C. [Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), P.O. Box 20632, Caracas 1020A (Venezuela, Bolivarian Republic of); Garcia, J.; Lohfink, A. [Department of Astronomy and Maryland Astronomy Center for Theory and Computation, University of Maryland, College Park, MD 20742 (United States); Kallman, T. R.; Witthoeft, M. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bautista, M. A. [Department of Physics, Western Michigan University, Kalamazoo, MI 49008 (United States); Palmeri, P.; Quinet, P., E-mail: egatuzz@ivic.gob.ve, E-mail: claudio@ivic.gob.ve, E-mail: javier@astro.umd.edu, E-mail: alohfink@astro.umd.edu, E-mail: timothy.r.kallman@nasa.gov, E-mail: michael.c.witthoeft@nasa.gov, E-mail: manuel.bautista@wmich.edu, E-mail: palmeri@umons.ac.be, E-mail: quinet@umons.ac.be [Astrophysique et Spectroscopie, Universite de Mons-UMONS, B-7000 Mons (Belgium)

    2013-05-01

    We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 A broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 A) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the XSTAR code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N{sub H} = 1.38 {+-} 0.01 Multiplication-Sign 10{sup 21} cm{sup -2}; an ionization parameter of log {xi} = -2.70 {+-} 0.023; an oxygen abundance of A{sub O}= 0.689{sup +0.015}{sub -0.010}; and ionization fractions of O I/O = 0.911, O II/O = 0.077, and O III/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse and Sauval, a rescaling with the revision by Asplund et al. yields A{sub O}=0.952{sup +0.020}{sub -0.013}, a value close to solar that reinforces the new standard. We identify several atomic absorption lines-K{alpha}, K{beta}, and K{gamma} in O I and O II and K{alpha} in O III, O VI, and O VII-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n > 2 associated with ISM cold absorption.

  1. The Influence of Water Vapor Absorption in the 290-350 nm Region on Solar Irradiance: Laboratory Studies and Model Simulation

    Science.gov (United States)

    Zhu, L.; Du, J.; Huang, L.; Min, Q.

    2015-12-01

    Water vapor is the most abundant greenhouse gas in the earth's atmosphere. Absorption of the solar radiation by water vapor in the near UV region may partially account for the up to 30% discrepancy between the modeled and the observed solar energy absorbed by the atmosphere. But the magnitude of water vapor absorption in the near UV region at wavelengths shorter than 384 nm was not known prior to this study. We have determined absorption cross sections of water vapor at 5 nm intervals in the 290-350 nm region, by using cavity ring-down spectroscopy. Water vapor cross section values range from 2.94×10-24 to 2.13×10-25 cm2/molecule in the wavelength region studied. The effect of the water vapor absorption in the 290-350 nm region on the modeled radiation flux at the ground level has been evaluated using radiative transfer model.

  2. Abnormal absorption and scattering effect of human ear model for electromagnetic waves

    Institute of Scientific and Technical Information of China (English)

    NIE Min; PEI Changxing; LI Jiandong; MA Chen; YANG Zhen

    2005-01-01

    @@ To explore the effect of human ear outline structure for electromagnetic waves, two human ear's models, a big one (model 1) and a small one (model 2), were made in proportion as real human ears (Fig. 1). The installation picture is shown in Fig. 2, and its geometry structure and size are shown in Figs. 3 and 4, respectively.

  3. Nanostructuring for enhanced absorption and carrier collection in CZTS-based solar cells: Coupled optical and electrical modeling

    Science.gov (United States)

    Abdelraouf, Omar A. M.; Allam, Nageh K.

    2016-04-01

    Earth-abundant Cu2ZnSnS4 (CZTS) is being considered as a potential photon-absorbing layer for low cost thin film solar cells. Nanostructured light trapping is recently investigated as a technique for enhancing the efficiency of CZTS solar cells. Herein, we used coupled electrical and optical modeling for different combinations of nanostructured CZTS solar cells to guide optimization of such nanostructures. The model is validated by a comparison of simulated I-V curves with previously reported experimental data. A very good agreement is achieved. Simulations are used to demonstrate that nanostructures can be tailored to maximize the absorption, carrier generation, carrier collection, and efficiency in CZTS solar cells. All proposed nanostructured solar cells showed enhancement in the overall conversion efficiency.

  4. On the Use of Difference Bands for Modeling SF_6 Absorption in the 10μm Atmospheric Window

    Science.gov (United States)

    Faye, Mbaye; Manceron, Laurent; Roy, P.; Boudon, Vincent; Loete, Michel

    2016-06-01

    To model correctly the SF_6 atmospheric absorption requires the knowledge of the spectroscopic parameters of all states involved in the numerous hot bands in the 10,5μm atmospheric transparency window. However, due to their overlapping, a direct analysis of the hot bands near the 10,5μm absorption of SF_6 in the atmospheric window is not possible. It is necessary to use another strategy, gathering information in the far and mid infrared regions on initial and final states to compute the relevant total absorption. In this talk, we present new results from the analysis of spectra recorded at the AILES beamline at the SOLEIL Synchrotron facility. For these measurements, we used a IFS125HR interferometer combined with the synchrotron radiation in the 100-3200 wn range, coupled to a cryogenic multiple pass cell. The optical path length was varied from 45 to 141m with measuring temperatures between 223 and 153+/-5 K. The new information obtained on νb{2}+νb{4}-νb{5}, 2νb{5}-νb{6} and νb{3}+νb{6}-νb{4} allowed to derive improved parameters for νb{5}, 2νb{5} and νb{3}+νb{6}. In turn, they are used to model the more important νb{3}+νb{5}-νb{5} and νb{3}+νb{6}-νb{6} hot band contributions. By including these new parameters in the XTDS model, we substantially improved the SF_6 parameters used to model the atmosphere. F. Kwabia Tchana, F. Willaert, X. Landsheere, J. M. Flaud, L. Lago, M. Chapuis, P. Roy, L. Manceron. A new, low temperature long-pass cell for mid-IR to THz Spectroscopy and Synchrotron Radiation Use. Rev. Sci. Inst. 84, 093101, (2013) C. Wenger, V. Boudon, M. Rotger, M. Sanzharov, and J.-P. Champion,"XTDS and SPVIEW: Graphical tools for Analysis and Simulation of High Resolution Molecular Spectra", J. Mol. Spectrosc. 251, 102 (2008)

  5. Comparison of models of fast saturable absorption in passively modelocked lasers.

    Science.gov (United States)

    Wang, Shaokang; Marks, Brian S; Menyuk, Curtis R

    2016-09-01

    Fast saturable absorbers (FSAs) play a critical role in stabilizing many passively modelocked lasers. The most commonly used averaged model to study these lasers is the Haus modelocking equation (HME) that includes a third-order nonlinear FSA. However, it predicts a narrow region of stability that is inconsistent with experiments. To better replicate the laser physics, averaged laser models that include FSAs with higher-than-third-order nonlinearities have been introduced. Here, we compare three common FSA models to each other and to the HME using the recently-developed boundary tracking algorithms. The three FSA models are the cubic-quintic model, the sinusoidal model, and the algebraic model. We find that all three models predict the existence of a stable high-energy solution that is not present in the HME and have a much larger stable operating region. We also find that all three models predict qualitatively similar stability diagrams. We conclude that averaged laser models that include FSAs with higher-than-third-order nonlinearity should be used when studying the stability of passively modelocked lasers. PMID:27607630

  6. Comparison of models of fast saturable absorption in passively modelocked lasers.

    Science.gov (United States)

    Wang, Shaokang; Marks, Brian S; Menyuk, Curtis R

    2016-09-01

    Fast saturable absorbers (FSAs) play a critical role in stabilizing many passively modelocked lasers. The most commonly used averaged model to study these lasers is the Haus modelocking equation (HME) that includes a third-order nonlinear FSA. However, it predicts a narrow region of stability that is inconsistent with experiments. To better replicate the laser physics, averaged laser models that include FSAs with higher-than-third-order nonlinearities have been introduced. Here, we compare three common FSA models to each other and to the HME using the recently-developed boundary tracking algorithms. The three FSA models are the cubic-quintic model, the sinusoidal model, and the algebraic model. We find that all three models predict the existence of a stable high-energy solution that is not present in the HME and have a much larger stable operating region. We also find that all three models predict qualitatively similar stability diagrams. We conclude that averaged laser models that include FSAs with higher-than-third-order nonlinearity should be used when studying the stability of passively modelocked lasers.

  7. Comparison of Models of Fast Saturable Absorption in Passively Modelocked Lasers

    CERN Document Server

    Wang, Shaokang; Menyuk, Curtis R

    2016-01-01

    Fast saturable absorbers (FSAs) play a critical role in stabilizing many passively modelocked lasers. The most commonly used averaged model to study these lasers is the Haus modelocking equation (HME) that includes a third-order nonlinear FSA. However, it predicts a narrow region of stability that is inconsistent with experiments. To better replicate the laser physics, averaged laser models that include FSAs with higher-than-third-order nonlinearities have been introduced. Here, we compare three common FSA models to each other and to the HME using the recently-developed boundary tracking algorithms. The three FSA models are the cubic-quintic model, the sinusoidal model, and the algebraic model. We find that all three models predict the existence of a stable high-energy solution that is not present in the HME and have a much larger stable operating region. We also find that all three models predict qualitatively similar stability diagrams. We conclude that averaged laser models that include FSAs with higher-th...

  8. The New Cloud Absorption Radiometer (CAR) Software: One Model for NASA Remote Sensing Virtual Instruments

    Science.gov (United States)

    Roth, Don J.; Rapchun, David A.; Jones, Hollis H.

    2001-01-01

    The Cloud Absorption Radiometer (CAR) instrument has been the most frequently used airborne instrument built in-house at NASA Goddard Space Flight Center, having flown scientific research missions on-board various aircraft to many locations in the United States, Azores, Brazil, and Kuwait since 1983. The CAR instrument is capable of measuring scattered light by clouds in fourteen spectral bands in UV, visible and near-infrared region. This document describes the control, data acquisition, display, and file storage software for the new version of CAR. This software completely replaces the prior CAR Data System and Control Panel with a compact and robust virtual instrument computer interface. Additionally, the instrument is now usable for the first time for taking data in an off-aircraft mode. The new instrument is controlled via a LabVIEW v5. 1.1-developed software interface that utilizes, (1) serial port writes to write commands to the controller module of the instrument, and (2) serial port reads to acquire data from the controller module of the instrument. Step-by-step operational procedures are provided in this document. A suite of other software programs has been developed to complement the actual CAR virtual instrument. These programs include: (1) a simulator mode that allows pretesting of new features that might be added in the future, as well as demonstrations to CAR customers, and development at times when the instrument/hardware is off-location, and (2) a post-experiment data viewer that can be used to view all segments of individual data cycles and to locate positions where 'start' and stop' byte sequences were incorrectly formulated by the instrument controller. The CAR software described here is expected to be the basis for CAR operation for many missions and many years to come.

  9. Physiologically Based Absorption Modeling to Impact Biopharmaceutics and Formulation Strategies in Drug Development-Industry Case Studies.

    Science.gov (United States)

    Kesisoglou, Filippos; Chung, John; van Asperen, Judith; Heimbach, Tycho

    2016-09-01

    In recent years, there has been a significant increase in use of physiologically based pharmacokinetic models in drug development and regulatory applications. Although most of the published examples have focused on aspects such as first-in-human (FIH) dose predictions or drug-drug interactions, several publications have highlighted the application of these models in the biopharmaceutics field and their use to inform formulation development. In this report, we present 5 case studies of use of such models in this biopharmaceutics/formulation space across different pharmaceutical companies. The case studies cover different aspects of biopharmaceutics or formulation questions including (1) prediction of absorption prior to FIH studies; (2) optimization of formulation and dissolution method post-FIH data; (3) early exploration of a modified-release formulation; (4) addressing bridging questions for late-stage formulation changes; and (5) prediction of pharmacokinetics in the fed state for a Biopharmaceutics Classification System class I drug with fasted state data. The discussion of the case studies focuses on how such models can facilitate decisions and biopharmaceutic understanding of drug candidates and the opportunities for increased use and acceptance of such models in drug development and regulatory interactions. PMID:26886317

  10. Understanding H isotope adsorption and absorption of Al-alloys using modeling and experiments (LDRD: #165724)

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Donald K. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Zhou, Xiaowang [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Karnesky, Richard A. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Kolasinski, Robert [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Foster, Michael E. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Thurmer, Konrad [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Chao, Paul [Carnegie Mellon University, Pittsburgh, PA (United States); Epperly, Ethan Nicholas [Livermore Valley Charter Preparatory High School, Livermore, CA (United States); Zimmerman, Jonathan A. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Wong, Bryan M. [Univ. of California, Riverside, CA (United States); Sills, Ryan B. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States)

    2015-09-01

    Current austenitic stainless steel storage reservoirs for hydrogen isotopes (e.g. deuterium and tritium) have performance and operational life-limiting interactions (e.g. embrittlement) with H-isotopes. Aluminum alloys (e.g.AA2219), alternatively, have very low H-isotope solubilities, suggesting high resistance towards aging vulnerabilities. This report summarizes the work performed during the life of the Lab Directed Research and Development in the Nuclear Weapons investment area (165724), and provides invaluable modeling and experimental insights into the interactions of H isotopes with surfaces and bulk AlCu-alloys. The modeling work establishes and builds a multi-scale framework which includes: a density functional theory informed bond-order potential for classical molecular dynamics (MD), and subsequent use of MD simulations to inform defect level dislocation dynamics models. Furthermore, low energy ion scattering and thermal desorption spectroscopy experiments are performed to validate these models and add greater physical understanding to them.

  11. Modeling unburned hydrocarbon formation due to absorption/desorption processes into the wall oil film

    International Nuclear Information System (INIS)

    This paper reports that as a result of continuing air pollution problems, very stringent regulations are being enforced to control emissions of unburned hydrocarbons (HC) from premixed-charge, spark-ignition engines. A number of attempts have been reported on modeling sources of HC emissions using various analytical tools. Over the past decade, the development of multi-dimensional reacting flow codes has advanced considerably. Perhaps the most widely used multi-dimensional engine simulation code is KIVA-II, which was developed at Lost Alamos National Laboratory. The ability to deal with moving boundary conditions caused by the piston movement is built in this code. This code also includes models for turbulent fluid flow, turbulent interaction between spray drops and gas, heat transfer, chemical reaction, and fuel spray. A standard k-ε turbulence model is used for gas flow. The fuel spray model is based on the stochastic particle technique, and includes sub-models for droplet injection, breakup, collision and coalescence, and evaporation

  12. Properties of damped Ly α absorption systems and star-forming galaxies in semi-analytic models at z = 2

    Science.gov (United States)

    Berry, Michael; Somerville, Rachel S.; Gawiser, Eric; Maller, Ariyeh H.; Popping, Gergö; Trager, Scott C.

    2016-05-01

    We investigate predictions from semi-analytic cosmological models of galaxy formation for the properties of star-forming galaxies (SFGs) and damped Ly α absorption systems (DLAS), and the relationship between these two populations. Our models reproduce fairly well the observed distributions of redshift, stellar mass, star formation rate (SFR), and dust extinction for z ˜ 2 SFGs. We predict that DLA hosts span a broad range of properties, with broad and relatively flat distributions of stellar and halo mass, SFR, and luminosity. The photometric colours of DLA host galaxies trace the colours of galaxies with similar luminosities, but the majority are much fainter than the limits of most existing surveys of SFGs. Generally, DLA host galaxies and SFGs at z = 2 follow similar trends between stellar mass, DLA cross-section, cold gas fraction, SFR, metallicity, and dust extinction as the global population of galaxies with the same stellar mass. Since DLAS select galaxies with larger cold gas masses, they tend to have larger cold gas fractions, lower metallicities, higher SFRs, and less dust extinction than galaxies at the same stellar mass. Our models reproduce the observed relations between impact parameter, column density, and metallicity, suggesting that the sizes of the gas discs giving rise to DLAS in our models are roughly correct. We find that molecular fractions and SFRs are in general significantly lower at the location of the DLA line of sight than the galaxy-averaged value.

  13. A hybrid geometric optical-radiative transfer approach for modeling light absorption and albedo of discontinuous canopies

    Institute of Scientific and Technical Information of China (English)

    李小文; 王锦地; Alan H.Strahler

    1995-01-01

    A new model for light-absorption and alhedo of a vegetation cover combines principles ofgeometric optics and radiative transfer.It relies on the gap probabilities and path length distributions to modelthe penetration of the irradiance from a parailel source and the single and multiple scattering of that irradi-ance.The model is applied to the vegetation covers of the discrete plant crowns that are randomly centredboth on the plane and within a layer of variable thickness(from h1 to h2)above it.Crowns assume a spheroi-dal shape with an arbitrary height to width ratio(B/R).Geometric optics easily models the irradianee thatpenetrates the vegetation cover directly,and is scattered by the soil,and exist without further scattering by thevegetation.Within a plant crown,the probability of scattering is a negative exponential function of pathlength.Within crown scattering provides the source for the singly scattered radiation,which provides thesource for double scattering,and then higher order pairs of scattering are solved successively by a convolution-like funaion.Early validations using data from a conifer stand near Howland,Maine of USA show reasonableagreement between the modeled and observed albedo.

  14. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  15. The spectral variability of the GHZ-Peaked spectrum radio source PKS 1718-649 and a comparison of absorption models

    Energy Technology Data Exchange (ETDEWEB)

    Tingay, S. J.; Macquart, J.-P.; Wayth, R. B.; Trott, C. M.; Emrich, D. [International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102 (Australia); Collier, J. D.; Wong, G. F. [University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751 (Australia); Rees, G.; Stevens, J.; Carretti, E. [CSIRO Astronomy and Space Science (CASS), PO Box 76, Epping, NSW 1710 (Australia); Callingham, J. R.; Gaensler, B. M. [Sydney Institute for Astronomy, School of Physics (SiFA), The University of Sydney, NSW 2006 (Australia); McKinley, B.; Briggs, F. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Bernardi, G. [Square Kilometre Array South Africa (SKA SA), Cape Town 7405 (South Africa); Bowman, J. D. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Cappallo, R. J.; Corey, B. E. [MIT Haystack Observatory, Westford, MA 01886 (United States); Deshpande, A. A. [Raman Research Institute, Bangalore 560080 (India); Goeke, R., E-mail: s.tingay@curtin.edu.au [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); and others

    2015-02-01

    Using the new wideband capabilities of the ATCA, we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over 3 epochs spanning approximately 21 months, reveal variability both above the spectral peak at ∼3 GHz and below the peak. The combination of the low- and high-frequency variability cannot be easily explained using a single absorption mechanism, such as free–free absorption or synchrotron self-absorption. We find that the PKS 1718-649 spectrum and its variability are best explained by variations in the free–free optical depth on our line of sight to the radio source at low frequencies (below the spectral peak) and the adiabatic expansion of the radio source itself at high frequencies (above the spectral peak). The optical depth variations are found to be plausible when X-ray continuum absorption variability seen in samples of active galactic nuclei is considered. We find that the cause of the peaked spectrum in PKS 1718-649 is most likely due to free–free absorption. In agreement with previous studies, we find that the spectrum at each epoch of observation is best fit by a free–free absorption model characterized by a power-law distribution of free–free absorbing clouds. This agreement is extended to frequencies below the 1 GHz lower limit of the ATCA by considering new observations with Parkes at 725 MHz and 199 MHz observations with the newly operational Murchison Widefield Array. These lower frequency observations argue against families of absorption models (both free–free and synchrotron self-absorption) that are based on simple homogenous structures.

  16. Maximum Recommended Dosage of Lithium for Pregnant Women Based on a PBPK Model for Lithium Absorption

    Directory of Open Access Journals (Sweden)

    Scott Horton

    2012-01-01

    Full Text Available Treatment of bipolar disorder with lithium therapy during pregnancy is a medical challenge. Bipolar disorder is more prevalent in women and its onset is often concurrent with peak reproductive age. Treatment typically involves administration of the element lithium, which has been classified as a class D drug (legal to use during pregnancy, but may cause birth defects and is one of only thirty known teratogenic drugs. There is no clear recommendation in the literature on the maximum acceptable dosage regimen for pregnant, bipolar women. We recommend a maximum dosage regimen based on a physiologically based pharmacokinetic (PBPK model. The model simulates the concentration of lithium in the organs and tissues of a pregnant woman and her fetus. First, we modeled time-dependent lithium concentration profiles resulting from lithium therapy known to have caused birth defects. Next, we identified maximum and average fetal lithium concentrations during treatment. Then, we developed a lithium therapy regimen to maximize the concentration of lithium in the mother’s brain, while maintaining the fetal concentration low enough to reduce the risk of birth defects. This maximum dosage regimen suggested by the model was 400 mg lithium three times per day.

  17. Absorption tuning of the green fluorescent protein chromophore: synthesis and studies of model compounds

    DEFF Research Database (Denmark)

    Brøndsted Nielsen, Mogens; Andersen, Lars Henrik; Rinza, Tomás Rocha

    2011-01-01

    The green fluorescent protein (GFP) chromophore is a heterocyclic compound containing a p-hydroxybenzylidine attached to an imidazol-5(4H)-one ring. This review covers the synthesis of a variety of model systems for elucidating the intrinsic optical properties of the chromophore in the gas phase...

  18. Radiation absorption and use by humid savanna grassland: assessment using remote sensing and modelling

    International Nuclear Information System (INIS)

    The components of the canopy radiation balance in photosynthetically active radiation (PAR), phytomass and leaf area index (LAI) were measured during a complete annual cycle in an annually burned African humid savanna. Directional reflectances measured by a hand-held radiometer were used to compute the canopy normalized difference vegetation index (NDVI). The fraction fAPAR of PAR absorbed by the canopy (APAR) and canopy reflectances were simulated by the scattering from arbitrarily inclined leaves (SAIL) and the radiation interception in row intercropping (RIRI) models. The daily PAR to solar radiation ratio was linearly related to the daily fraction of diffuse solar radiation with an annual value around 0.47. The observed fAPAR was non-linearly related to NDVI. The SAIL model simulated reasonably well directional reflectances but noticeably overestimated fAPAR during most of the growing season. Comparison of simulations performed with the 1D and 3D versions of the RIRI model highlighted the weak influence of the heterogeneous structure of the canopy after fire and of the vertical distribution of dead and green leaves on total fAPAR. Daily fAPAR values simulated by the 3D-RIRI model were linearly related to and 9.8% higher than observed values. For sufficient soil water availability, the net production efficiency ϵn of the savanna grass canopy was 1.92 and 1.28 g DM MJ−1 APAR (where DM stands for dry matter) during early regrowth and mature stage, respectively. In conclusion, the linear relationship between NDVI and fAPAR used in most primary production models operating at large scales may slightly overestimate fAPAR by green leaves for the humid savanna biome. Moreover, the net production efficiency of humid savannas is close to or higher than values reported for the other major natural biomes. (author)

  19. ITM-Based FSI-Models for Rooms with Absorptive Boundaries

    OpenAIRE

    Buchschmid, Martin

    2012-01-01

    A method for room acoustical simulations has been developed in order to compute the sound field in acoustic cavities with compound absorbers, mounted at the walls. To reduce the number of degrees of freedom and therefore the numerical effort, a model reduction method, based on a Component Mode Synthesis (CMS), is applied. Macrostructures are assembled out of single substructures applying shape functions at the interfaces. These substructures contain acoustic components like porous absorbers o...

  20. Correlation of in vitro and in vivo models for the oral absorption of peptide drugs.

    Science.gov (United States)

    Föger, F; Kopf, A; Loretz, B; Albrecht, K; Bernkop-Schnürch, A

    2008-06-01

    The aim of this study was to evaluate two in vitro models, Caco-2 monolayer and rat intestinal mucosa, regarding their linear correlation with in vivo bioavailability data of therapeutic peptide drugs after oral administration in rat and human. Furthermore the impact of molecular mass (Mm) of the according peptides on their permeability was evaluated. Transport experiments with commercially available water soluble peptide drugs were conducted using Caco-2 cell monolayer grown on transwell filter membranes and with freshly excised rat intestinal mucosa mounted in Using type chambers. Apparent permeability coefficients (P (app)) were calculated and compared with in vivo data derived from the literature. It was shown that, besides a few exceptions, the Mm of peptides linearly correlates with permeability across rat intestinal mucosa (R (2) = 0.86; y = -196.22x + 1354.24), with rat oral bioavailability (R (2) = 0.64; y = -401.90x + 1268.86) as well as with human oral bioavailability (R (2) = 0.91; y = -359.43x + 1103.83). Furthermore it was shown that P (app) values of investigated hydrophilic peptides across Caco-2 monolayer displayed lower permeability than across rat intestinal mucosa. A correlation between P (app) values across rat intestinal mucosa and in vivo oral bioavailability in human (R (2) = 0.98; y = 2.11x + 0.34) attests the rat in vitro model to be a very useful prediction model for human oral bioavailability of hydrophilic peptide drugs. Presented correlations encourage the use of the rat in vitro model for the prediction of human oral bioavailabilities of hydrophilic peptide drugs.

  1. Regional Climate Zone Modeling of a Commercial Absorption Heat Pump Hot Water Heater Part 1: Southern and South Central Climate Zones

    Energy Technology Data Exchange (ETDEWEB)

    Geoghegan, Patrick J [ORNL; Shen, Bo [ORNL; Keinath, Christopher M. [Stone Mountain Technologies, Inc., Johnson City; Garrabrant, Michael A. [Stone Mountain Technologies, Inc., Johnson City

    2016-01-01

    Commercial hot water heating accounts for approximately 0.78 Quads of primary energy use with 0.44 Quads of this amount from natural gas fired heaters. An ammonia-water based commercial absorption system, if fully deployed, could achieve a high level of savings, much higher than would be possible by conversion to the high efficiency nonheat-pump gas fired alternatives. In comparison with air source electric heat pumps, the absorption system is able to maintain higher coefficients of performance in colder climates. The ammonia-water system also has the advantage of zero Ozone Depletion Potential and low Global Warming Potential. A thermodynamic model of a single effect ammonia-water absorption system for commercial space and water heating was developed, and its performance was investigated for a range of ambient and return water temperatures. This allowed for the development of a performance map which was then used in a building energy modeling software. Modeling of two commercial water heating systems was performed; one using an absorption heat pump and another using a condensing gas storage system. The energy and financial savings were investigated for a range of locations and climate zones in the southern and south central United States. A follow up paper will analyze northern and north/central regions. Results showed that the system using an absorption heat pump offers significant savings.

  2. Hand effect on head specific absorption rate (SAR) exposed by two realistic phone models

    International Nuclear Information System (INIS)

    There have been some reports about possible effect of the hand presence on the head SAR if hand phantom is included in the measurements of the head SAR compliance assessment procedure. The objective of this computational study was to examine the reported effect by using realistic head models and realistic CAD based phone models. A commercially available FDTD based EM solver was used to carry out the computational work. Based on the results of this study considering the SAR values without hand phantom as reference, following conclusions can be made: 1. In general presence of the hand lead to significantly less conservative SAR values in the head for large majority of cases 2. For lower band GSM frequencies the presence of the hand decreases the head SAR up to ∼70%. 3. For the upper band GSM frequencies the presence of the hand decreases the head SAR up to ∼55%. Based on the results of this study the present SAR compliance protocol where hand phantom is not included leads to more conservative head SAR results compared to the cases where hand is included.

  3. A heuristic model to quantify the impact of excess cyclodextrin on oral drug absorption from aqueous solution.

    Science.gov (United States)

    Olesen, Niels Erik; Westh, Peter; Holm, René

    2016-05-01

    The intestinal drug solubilising capacity (Dtot(SC)) of a drug formulated as an aqueous cyclodextrin solution is a recently proposed quantity to predict the cyclodextrin concentration needed to fully solubilise the drug in the intestinal lumen. According to this concept, the cyclodextrin concentration in the drug product must be higher than the amount needed to solubilise the compound, due to the displacement of the drug from the cyclodextrin cavity by bile salts in the intestinal lumen. On the other hand, dosing cyclodextrin at >Dtot(SC) is expected to result in decreased free intestinal drug concentrations and thus potentially a lower fraction absorbed. In this study, data from three previous in vivo studies in rats with fixed concentrations of three compounds (danazol, cinnarizine and benzo[A]pyrene) and various cyclodextrin concentrations >Dtot(SC) were analysed. The model was developed for danazol and applied to the two other compounds. Absorption, as quantified from the area under the plasma concentration-time profile, was predicted by the model to decrease at elevated concentrations of co-administered cyclodextrin in accordance with the in vivo data. In addition, at high cyclodextrin concentrations a delay in Tmax and a decrease in Cmax were predicted, again in accordance with the experimental observations. These observations were rationalised in terms of the free intestinal drug concentration by a chemical equilibrium model for Dtot(SC). This model depends on the quantity termed the dimensionless dose concentration, Dtot(∗)=Do/Pn, given as the fraction of the permeation number (Pn) and dose number (Do). The model provides the formulation scientist with a critical quality attribute for assessing the implication of having excess cyclodextrin in an oral solution. PMID:26969263

  4. Use of Modeling and Simulation Tools for Understanding the Impact of Formulation on the Absorption of a Low Solubility Compound: Ciprofloxacin.

    Science.gov (United States)

    Martinez, Marilyn; Mistry, Bipin; Lukacova, Viera; Polli, Jim; Hoag, Stephen; Dowling, Thomas; Kona, Ravikanth; Fahmy, Raafat

    2016-07-01

    This study explored the utility of mechanistic absorption models to describe the in vivo performance of a low solubility/low permeability compound in normal healthy subjects. Sixteen healthy human volunteers received three oral formulations and an intravenous infusion in a randomized crossover design. Plasma ciprofloxacin concentrations were estimated by HPLC. In vitro ciprofloxacin release from the oral tablets was tested under a variety of conditions. A mechanistic model was used to explore in vivo dissolution and intestinal absorption. Although dissolution rate influenced the location of drug release, absorption challenges appeared to be associated with permeability limitations in the lower small intestine and colon. The apparent relationship between drug solubilization within the upper small intestinal and formulation overall bioavailability suggested the presence of an intestinal absorption window in many individuals. Failure to absorb drug within this window appeared to be linked with the likelihood of in vivo drug precipitation. Challenges encountered during this modeling exercise included large intersubject variability in product in vivo dissolution and the apparent limitations in ciprofloxacin absorption. Although transporter activity was not included as a model parameter, this evaluation demonstrated how identifying the location of drug absorption across several formulations provided an opportunity to identify factors to consider when formulating similar low solubility/low permeability compounds. The use of mechanistic models was invaluable for our understanding of in vivo product performance and for the assessment of individual profiles rather than means. The latter was essential for understanding the potential challenges that may be encountered when introducing a formulation into a patient population. PMID:27116024

  5. X-ray Absorption Spectroscopic Quantification and Speciation Modeling of Sulfate Adsorption on Ferrihydrite Surfaces.

    Science.gov (United States)

    Gu, Chunhao; Wang, Zimeng; Kubicki, James D; Wang, Xiaoming; Zhu, Mengqiang

    2016-08-01

    Sulfate adsorption on mineral surfaces is an important environmental chemical process, but the structures and respective contribution of different adsorption complexes under various environmental conditions are unclear. By combining sulfur K-edge XANES and EXAFS spectroscopy, quantum chemical calculations, and surface complexation modeling (SCM), we have shown that sulfate forms both outer-sphere complexes and bidentate-binuclear inner-sphere complexes on ferrihydrite surfaces. The relative fractions of the complexes vary with pH, ionic strength (I), and sample hydration degree (wet versus air-dried), but their structures remained the same. The inner-sphere complex adsorption loading decreases with increasing pH while remaining unchanged with I. At both I = 0.02 and 0.1 M, the outer-sphere complex loading reaches maximum at pH ∼5 and then decreases with pH, whereas it monotonically decreases with pH at I = 0.5 M. These observations result from a combination of the ionic-strength effect, the pH dependence of anion adsorption, and the competition between inner- and outer-sphere complexation. Air-drying drastically converts the outer-sphere complexes to the inner-sphere complexes. The respective contributions to the overall adsorption loading of the two complexes were directly modeled with the extended triple layer SCM by implementing the bidentate-binuclear inner-sphere complexation identified in the present study. These findings improve our understanding of sulfate adsorption and its effects on other environmental chemical processes and have important implications for generalizing the adsorption behavior of anions forming both inner- and outer-sphere complexes on mineral surfaces. PMID:27377619

  6. Monitoring the initial pulmonary absorption of two different beclomethasone dipropionate aerosols employing a human lung reperfusion model

    Directory of Open Access Journals (Sweden)

    Fritz Peter

    2005-02-01

    Full Text Available Abstract Background The pulmonary residence time of inhaled glucocorticoids as well as their rate and extend of absorption into systemic circulation are important facets of their efficacy-safety profile. We evaluated a novel approach to elucidate the pulmonary absorption of an inhaled glucocorticoid. Our objective was to monitor and compare the combined process of drug particle dissolution, pro-drug activation and time course of initial distribution from human lung tissue into plasma for two different glucocorticoid formulations. Methods We chose beclomethasone dipropionate (BDP delivered by two different commercially available HFA-propelled metered dose inhalers (Sanasthmax®/Becloforte™ and Ventolair®/Qvar™. Initially we developed a simple dialysis model to assess the transfer of BDP and its active metabolite from human lung homogenate into human plasma. In a novel experimental setting we then administered the aerosols into the bronchus of an extracorporally ventilated and reperfused human lung lobe and monitored the concentrations of BDP and its metabolites in the reperfusion fluid. Results Unexpectedly, we observed differences between the two aerosol formulations Sanasthmax®/Becloforte™ and Ventolair®/Qvar™ in both the dialysis as well as in the human reperfusion model. The HFA-BDP formulated as Ventolair®/Qvar™ displayed a more rapid release from lung tissue compared to Sanasthmax®/Becloforte™. We succeeded to explain and illustrate the observed differences between the two aerosols with their unique particle topology and divergent dissolution behaviour in human bronchial fluid. Conclusion We conclude that though the ultrafine particles of Ventolair®/Qvar™ are beneficial for high lung deposition, they also yield a less desired more rapid systemic drug delivery. While the differences between Sanasthmax®/Becloforte™ and Ventolair®/Qvar™ were obvious in both the dialysis and lung perfusion experiments, the latter

  7. Investigation of the effects of soluble fibers on the absorption of resveratrol and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PHIP) in the Caco-2 cellular model of intestinal absorption.

    Science.gov (United States)

    Willenberg, Ina; Wonik, Jasmin; Schebb, Nils Helge

    2015-01-01

    Soluble fibers are known to modulate intestinal absorption of non-polar compounds in the small intestine. Little is known about the modulation of absorption of more polar compounds. In the present study, we applied the Caco-2-transwell-system in order to investigate the modulation of intestinal bioavailability by soluble fibers. The system was tested using pectin and carrageenan as model soluble fibers at a concentration of 0.1% (w/v), which did not compromise the integrity of the cell monolayer. Modulation of absorption was evaluated for the heterocyclic amine aromatic 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PHIP) and the polyphenol resveratrol. Neither pectin nor carrageenan reduced the high flux of PHIP, apparent permeability coefficient (Papp) of 16 × 10(-6) cm s(-1). The low Papp of resveratrol was reduced by both soluble fibers, particularly by pectin. These results suggest that the low bioavailability of polyphenols could be further reduced by soluble fibers. Because of their co-occurrence in several fruits, these findings warrant further research.

  8. Harmonic Models in Cartesian and Internal Coordinates to Simulate the Absorption Spectra of Carotenoids at Finite Temperatures.

    Science.gov (United States)

    Cerezo, Javier; Zúñiga, José; Requena, Alberto; Ávila Ferrer, Francisco J; Santoro, Fabrizio

    2013-11-12

    When large structural displacements take place between the ground state (GS) and excited state (ES) minima of polyatomic molecules, the choice of a proper set of coordinates can be crucial for a reliable simulation of the vibrationally resolved absorption spectrum. In this work, we study two carotenoids that undergo structural displacements from GS to ES minima of different magnitude, from small displacements for violaxanthin to rather large ones for β-carotene isomers. Their finite-temperature (77 and 300 K) spectra are simulated at the harmonic level, including Duschinsky effect, by time-dependent (TD) and time-independent (TI) approaches, using (TD)DFT computed potential energy surfaces (PES). We adopted two approaches to construct the harmonic PES, the Adiabatic (AH) and Vertical Hessian (VH) models and, for AH, two reference coordinate frames: Cartesian and valence internal coordinates. Our results show that when large displacements take place, Cartesian coordinates dramatically fail to describe curvilinear displacements and to account for the Duschinsky matrix, preventing a realistic simulation of the spectra within the AH model, where the GS and ES PESs are quadratically expanded around their own equilibrium geometry. In contrast, internal coordinates largely amend such deficiencies and deliver reasonable spectral widths. As expected, both coordinate frames give similar results when small displacements occur. The good agreement between VH and experimental line shapes indicates that VH model, in which GS and ES normal modes are both evaluated at the GS equilibrium geometry, is a good alternative to deal with systems exhibiting large displacements. The use of this model can be, however, problematic when imaginary frequencies arise. The extent of the nonorthogonality of the Dushinsky matrix in internal coordinates and its correlation with the magnitude of the displacement of the GS and ES geometries is analyzed in detail.

  9. Renormalization Group Approach to the X-Ray Absorption Problem and Application to the Vigman-Finkelshtein Model for Magnetic Impurities in Metals.

    Science.gov (United States)

    Nunes de Oliveira, Luiz

    The renormalization group techniques developed by Wilson for the Kondo problem are applied to three related problems: the absorption of x-rays by metals, the absorption of x-rays by impurities in metals, and the specific heat of dilute magnetic alloys. In the first problem considered, the x-ray absorption problem, the metal is represented by a half-filled conduction band and a deep level representing a core state. The absorption of an x-ray photon excites an electron from this core level to the conduction band creating a core hole whose positive charge interacts with the conduction electrons. The absorption spectrum is, for the first time, calculated in the energy range 10('-10)D ) (omega)(,T)) expression to seven decimal places; the prefactor (mu)(,o) is calculated for the first time. For (omega)-(omega)(,T) (TURNEQ) D, remarkably small deviations (e.g., deviations of 15% for (omega)-(omega)(,T) = .3D) from the Nozieres-De Dominicis power law are found. As a second application of the renormalization group techniques, the x-ray absorption spectrum for the resonant level model for impurities in metals is calculated. In this model, the metal is represented by a half-filled conduction band and the impurity by two levels: a core level from which an electron is excited to the conduction band by the absorption of an x-ray photon, and a resonant level, coupled to the conduction electrons, whose energy is lowered by the interaction with the core hole created by the absorption of the x-ray. In the x-ray absorption process, the resonant level is thus shifted to lower energy. The absorption spectrum approaches a power law in the energy range (omega)-(omega)(,T) >> (GAMMA), where (GAMMA) is the width of the resonant level, and a different power law in the range (omega)-(omega)(,T) body effect found in the spectrum of certain systems having a discrete level coupled to a continuum of energies) is elaborated. The problem of the specific heat of dilute magnetic alloys is attacked

  10. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  11. Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice

    NARCIS (Netherlands)

    Willige, van R.W.G.; Linssen, J.P.H.; Legger, A.; Voragen, A.G.J.

    2003-01-01

    The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic f

  12. Model calculation of the characteristic mass for convective and diffusive vapor transport in graphite furnace atomic absorption spectrometry

    Science.gov (United States)

    Bencs, László; Laczai, Nikoletta; Ajtony, Zsolt

    2015-07-01

    A combination of former convective-diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass - m0) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m0 values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm3 min- 1) of the internal sheath gas during atomization. The theoretical and experimental ratios of m0(mini-flow)-to-m0(stop-flow) were closely similar for each study analyte. Likewise, the calculated m0 data gave a fairly good agreement with the corresponding experimental m0 values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology.

  13. In Situ Perfusion Model in Rat Colon for Drug Absorption Studies: Comparison with Small Intestine and Caco-2 Cell Model.

    Science.gov (United States)

    Lozoya-Agullo, Isabel; González-Álvarez, Isabel; González-Álvarez, Marta; Merino-Sanjuán, Matilde; Bermejo, Marival

    2015-09-01

    Our aim is to develop and to validate the in situ closed loop perfusion method in rat colon and to compare with small intestine and Caco-2 cell models. Correlations with human oral fraction absorbed (Fa) and human colon fraction absorbed (Fa_colon) were developed to check the applicability of the rat colon model for controlled release (CR) drug screening. Sixteen model drugs were selected and their permeabilities assessed in rat small intestine and colon, and in Caco-2 monolayers. Correlations between colon/intestine/Caco-2 permeabilities versus human Fa and human Fa_colon have been explored to check model predictability and to apply a BCS approach in order to propose a cut off value for CR screening. Rat intestine perfusion with Doluisio's method and single-pass technique provided a similar range of permeabilities demonstrating the possibility of combining data from different laboratories. Rat colon permeability was well correlated with Caco-2 cell-4 days model reflecting a higher paracellular permeability. Rat colon permeabilities were also higher than human colon ones. In spite of the magnitude differences, a good sigmoidal relationship has been shown between rat colon permeabilities and human colon fractions absorbed, indicating that rat colon perfusion can be used for compound classification and screening of CR candidates.

  14. Superconductivity, Faraday effect, and optical absorption in the commensurate flux phase of the t-J model

    Science.gov (United States)

    Rodriguez, J. P.; Douçot, B.

    1992-01-01

    Using a large-N slave-boson formulation of the t-J model on the square lattice that has explicit spinon-holon decoupling of the correlated electron, we study the stability and electromagnetic response of the commensurate flux phase in the limit near half filling. A region of stability for the flux phase is found located between a dimer phase region near half filling and a fluxless metallic phase region far from half filling. The commensurate flux phase itself is found to be a superconductor of the anyon type. Furthermore, it is shown that the parity-time-reversal-violating characteristic of this phase results in a frequency-dependent Faraday effect. This effect manifests itself as a zero-field Hall effect in the low-frequency limit, where the off-diagonal conductance scales with the hole concentration. Associated with this result, it is also found that the commensurate flux phase supports a series of optical absorption peaks at energies on the order of J. Lastly, inclusion of instanton tunneling events in the effective gauge-field action results in the confinement of the spinon and holon degrees of freedom. This confinement effect, however, weakens exponentially as one approaches the Mott transition. The present results are discussed in the context of the high-Tc superconducting oxides.

  15. Modeling the absorption behavior of solar thermal collector coatings utilizing graded alpha-C:H/TiC layers.

    Science.gov (United States)

    Gruber, D P; Engel, G; Sormann, H; Schüler, A; Papousek, W

    2009-03-10

    Wavelength selective coatings are of common use in order to enhance the efficiency of devices heated by radiation such as solar thermal collectors. The use of suitable materials and the optimization of coating layer thicknesses are advisable ways to maximize the absorption. Further improvement is achievable by embedding particles in certain layers in order to modify material properties. We focus on optimizing the absorption behavior of a solar collector setup using copper as substrate, a layer of amorphous hydrogenated carbon with embedded titanium carbide particles (a-C:H/TiC), and an antireflection coating of amorphous silicon dioxide (aSiO(2)). For the setup utilizing homogeneous particle distribution, a relative absorption of 90.98% was found, while inhomogeneous particle embedding yielded 98.29%. These results are particularly interesting since until now, absorption of more than 95% was found only by using embedded Cr but not by using the more biocompatible Ti.

  16. Scanning imaging absorption spectrometer for atmospheric chartography carbon monoxide total columns: statistical evaluation and comparison with chemistry transport model results

    NARCIS (Netherlands)

    de Laat, A.T.J.; Gloudemans, A.M.S.; Aben, I.; Krol, M.C.; Meirink, J.F.; van der Werf, G.R.; Schrijver, H.

    2007-01-01

    This paper presents a detailed statistical analysis of one year (September 2003 to August 2004) of global Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) carbon monoxide (CO) total column retrievals from the Iterative Maximum Likelihood Method (IMLM) algorithm, vers

  17. Scanning Imaging Absorption Spectrometer for Atmospheric Chartography carbon monoxide total columns: Statistical evaluation and comparison with chemistry transport model results

    NARCIS (Netherlands)

    Laat, de A.T.J.; Gloudemans, A.M.S.; Aben, I.; Krol, M.C.; Meirink, J.F.; Werf, van der G.R.; Schrijver, H.

    2007-01-01

    This paper presents a detailed statistical analysis of one year (September 2003 to August 2004) of global Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) carbon monoxide (CO) total column retrievals from the Iterative Maximum Likelihood Method (IMLM) algorithm, vers

  18. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    Energy Technology Data Exchange (ETDEWEB)

    Anselmi, Massimiliano, E-mail: m.anselmi@caspur.it [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Marocchi, Simone [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Aschi, Massimiliano [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Via Vetoio (Coppito 1), 67100 Coppito, L' Aquila (Italy); Amadei, Andrea [Department of Chemistry, University of Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Rome (Italy)

    2012-01-02

    Highlights: Black-Right-Pointing-Pointer The calculated absorption spectra were compared with experimental data. Black-Right-Pointing-Pointer Shapes and absorption maxima were reproduced for luciferin and oxyluciferin spectra. Black-Right-Pointing-Pointer The effect of the solvent largely changes the electronic transition probabilities. Black-Right-Pointing-Pointer Higher excitations provide an important contribution to the main absorption peak. - Abstract: Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  19. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    International Nuclear Information System (INIS)

    Highlights: ► The calculated absorption spectra were compared with experimental data. ► Shapes and absorption maxima were reproduced for luciferin and oxyluciferin spectra. ► The effect of the solvent largely changes the electronic transition probabilities. ► Higher excitations provide an important contribution to the main absorption peak. - Abstract: Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  20. Frequency Comb Spectroscopy of CO(2), CH(4), H(2)O, and Isotopes Over a 2 km Outdoor Path: Concentration Retrievals Using Different Absorption Models

    Science.gov (United States)

    Rieker, G. B.; Giorgetta, F. R.; Coddington, I.; Swann, W. C.; Zolot, A. M.; Sinclair, L. C.; Baumann, E.; Cromer, C.; Newbury, N.

    2014-06-01

    A dual frequency comb spectrometer is used to make high signal-to-noise measurements of atmospheric absorption from 5990 to 6260 cm-1 with 0.0033 cm-1 point spacing and ˜4·10-8 cm-1 resolution over a 2 km outdoor air path. The spectra, which encompass over 700 absorption features of CO2, CH4, and H2O, are fit with several absorption models to assess the quality of the models and to retrieve the various species concentrations and air temperature. The models tested include the HITRAN 2008 and 2012 spectral databases with Voigt line-shape profiles as well as a recent model for CO2 that includes the effects of line mixing and speed dependence. Residuals are typically less than 2% of the peak absorbance, except for the HITRAN 2012 CH4 model, which exhibits larger residuals. Species concentration retrievals using the models are compared with a calibrated point sensor mounted on a tower near the open air path.

  1. A two-dimensional mathematical model of non-linear dual-sorption of percutaneous drug absorption

    Directory of Open Access Journals (Sweden)

    George K

    2005-07-01

    Full Text Available Abstract Background Certain drugs, for example scopolamine and timolol, show non-linear kinetic behavior during permeation process. This non-linear kinetic behavior is due to two mechanisms; the first mechanism being a simple dissolution producing mobile and freely diffusible molecules and the second being an adsorption process producing non-mobile molecules that do not participate in the diffusion process. When such a drug is applied on the skin surface, the concentration of the drug accumulated in the skin and the amount of the drug eliminated into the blood vessel depend on the value of a parameter, C, the donor concentration. The present paper studies the effect of the parameter value, C, when the region of the contact of the skin with drug, is a line segment on the skin surface. To confirm that dual-sorption process gives an explanation to non-linear kinetic behavior, the characteristic features that are used in one-dimensional models are (1 prolongation of half-life if the plot of flux versus time are straight lines soon after the vehicle removal, (2 the decrease in half-life with increase in donor concentration. This paper introduces another feature as a characteristic to confirm that dual-sorption model gives an explanation to the non-linear kinetic behavior of the drug. This new feature is "the prolongation of half-life is not a necessary feature if the plots of drug flux versus time is a non-linear curve, soon after the vehicle removal". Methods From biological point of view, a drug absorption model is said to be nonlinear if the sorption isotherm is non-linear. When a model is non-linear the relationship between lag-time and donor concentration is non-linear and the lag time decreases with increase in donor concentration. A two-dimensional dual-sorption model is developed for percutaneous absorption of a drug, which shows non-linear kinetic behavior in the permeation process. This model may be used when the diffusion of the drug in

  2. Model calculation of the characteristic mass for convective and diffusive vapor transport in graphite furnace atomic absorption spectrometry

    International Nuclear Information System (INIS)

    A combination of former convective–diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass — m0) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m0 values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm3 min−1) of the internal sheath gas during atomization. The theoretical and experimental ratios of m0(mini-flow)-to-m0(stop-flow) were closely similar for each study analyte. Likewise, the calculated m0 data gave a fairly good agreement with the corresponding experimental m0 values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology. - Highlights: • A calculation scheme for convective–diffusive vapor loss in GFAAS is described. • Residence time (τ) formulas were compared for sensitivity (m0) in a THGA furnace. • Effects of the sample/platform dimension and dosing hole on τ were assessed. • Theoretical m0 of 18 analytes were calculated for stopped & mini furnace gas flows. • Experimental

  3. Model calculation of the characteristic mass for convective and diffusive vapor transport in graphite furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bencs, László, E-mail: bencs.laszlo@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Laczai, Nikoletta [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Ajtony, Zsolt [Institute of Food Science, University of West Hungary, H-9200 Mosonmagyaróvár, Lucsony utca 15–17 (Hungary)

    2015-07-01

    A combination of former convective–diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass — m{sub 0}) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m{sub 0} values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm{sup 3} min{sup −1}) of the internal sheath gas during atomization. The theoretical and experimental ratios of m{sub 0}(mini-flow)-to-m{sub 0}(stop-flow) were closely similar for each study analyte. Likewise, the calculated m{sub 0} data gave a fairly good agreement with the corresponding experimental m{sub 0} values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology. - Highlights: • A calculation scheme for convective–diffusive vapor loss in GFAAS is described. • Residence time (τ) formulas were compared for sensitivity (m{sub 0}) in a THGA furnace. • Effects of the sample/platform dimension and dosing hole on τ were assessed. • Theoretical m{sub 0} of 18 analytes were

  4. MAGNETOHYDRODYNAMIC MODELING OF THE ACCRETION SHOCKS IN CLASSICAL T TAURI STARS: THE ROLE OF LOCAL ABSORPTION IN THE X-RAY EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Bonito, R.; Argiroffi, C.; Peres, G. [Dip. di Fisica e Chimica, Università di Palermo, P.zza del Parlamento 1, I-90134 Palermo (Italy); Orlando, S.; Miceli, M.; Ibgui, L. [INAF-Osservatorio Astronomico di Palermo, P.zza del Parlamento 1, I-90134 Palermo (Italy); Matsakos, T. [Department of Astronomy and Astrophysics, The University of Chicago, Chicago, IL 60637 (United States); Stehle, C., E-mail: sbonito@astropa.unipa.it [LERMA, Observatoire de Paris, Université Pierre et Marie Curie, Ecole Normale Superieure, Universite Cergy-Pontoise, CNRS, F-75014 Paris (France)

    2014-11-10

    We investigate the properties of X-ray emission from accretion shocks in classical T Tauri stars (CTTSs), generated where the infalling material impacts the stellar surface. Both observations and models of the accretion process reveal several aspects that are still unclear: the observed X-ray luminosity in accretion shocks is below the predicted value, and the density versus temperature structure of the shocked plasma, with increasing densities at higher temperature, deduced from the observations, is at odds with that proposed in the current picture of accretion shocks. To address these open issues, we investigate whether a correct treatment of the local absorption by the surrounding medium is crucial to explain the observations. To this end, we describe the impact of an accretion stream on a CTTS by considering a magnetohydrodynamic model. From the model results, we synthesize the X-ray emission from the accretion shock by producing maps and spectra. We perform density and temperature diagnostics on the synthetic spectra, and we directly compare the results with observations. Our model shows that the X-ray fluxes inferred from the emerging spectra are lower than expected because of the complex local absorption by the optically thick material of the chromosphere and of the unperturbed stream. Moreover, our model, including the effects of local absorption, explains in a natural way the apparently puzzling pattern of density versus temperature observed in the X-ray emission from accretion shocks.

  5. A Preliminary Study on Dynamics and Models of N, P, K Absorption for High-Yield Cotton

    Institute of Scientific and Technical Information of China (English)

    WANG Ke-ru; LI Shao-kun; CAO Lian-pu; SONG Guang-jie; CHEN Gang; CAO Suan-zhu

    2003-01-01

    The field experiments were carried out to investigate the dynamics and models of N, P and K ab-sorption for the cotton plants with a lint of 3 000 kg ha-1 in Xinjiang. The main results were as follows: Thecontents of N, P2O5, K2O in cotton leaves, stems, squares and bolls decreased obviously with the time over thewhole growth duration and the falling extent was greater in high-yield cotton than in CK. Contents of N inleaves, squares and bolls, in particular in the leaves of fruit-bearing shoot was higher in high-yield cotton thanin CK. Contents of P2O5 in squares and bolls and that of K2O in stems were higher in high-yield cotton than inCK during the whole growing period. The accumulations of N, P2O5 and K2O in the cotton plants could be de-scribed with a logistic curve equation. There was the fastest nutrient uptake at about 90 d for N, 92 d for P2O5and 85 d for K2O after emergence, respectively. Total nutrient accumulation of N, P2 O5 and K2O was 385.8,244.7 and 340.3 kg ha-1 , respectively. Approximately 12.5 kg N, 8.0 kg P2O5 and 11.1 kg K2O were neededfor producing 100 kg lint with the leaves and stems under the super high yield condition of 3 000 kg ha-1 inXinjiang.

  6. A Quantitative Review and Meta-models of the Variability and Factors Affecting Oral Drug Absorption-Part II: Gastrointestinal Transit Time.

    Science.gov (United States)

    Abuhelwa, Ahmad Y; Foster, David J R; Upton, Richard N

    2016-09-01

    This study aimed to conduct a quantitative meta-analysis for the values of, and variability in, gastrointestinal (GI) transit times of non-disintegrating single-unit ("tablet") and multiple-unit ("pellets/multi-unit tablet") solid dosage forms, characterize the effect of food on the values and variability in these parameters and present quantitative meta-models of the distributions of GI transit times in the respective GI regions to help inform models of oral drug absorption. The literature was systemically reviewed for the values of, and the variability in, gastric, small intestinal and colonic transit times under fed and fasted conditions. Meta-analysis used the "metafor" package of the R language. Meta-models of GI transit were assumed to be log-normally distributed between the studied populations. Twenty-nine studies including 125 reported means and standard deviations were used in the meta-analysis. Caloric content of administered food increased variability and delayed the gastric transit of both pellets and tablets. Conversely, food caloric content reduced the variability but had no significant influence on the mean small intestinal transit time (SITT). Food had no significant effect on the transit time through the colon. The transit of pellets through the colon was significantly slower than that of single-unit tablets which is most likely related to their smaller size. GI transit times may influence the dissolution and absorption of oral drugs. The meta-models of GI transit times may be used as part of semi-physiological absorption models to characterize the influence of transit time on the dissolution, absorption and in vivo pharmacokinetic profiles of oral drugs. PMID:27439620

  7. A Quantitative Review and Meta-models of the Variability and Factors Affecting Oral Drug Absorption-Part II: Gastrointestinal Transit Time.

    Science.gov (United States)

    Abuhelwa, Ahmad Y; Foster, David J R; Upton, Richard N

    2016-09-01

    This study aimed to conduct a quantitative meta-analysis for the values of, and variability in, gastrointestinal (GI) transit times of non-disintegrating single-unit ("tablet") and multiple-unit ("pellets/multi-unit tablet") solid dosage forms, characterize the effect of food on the values and variability in these parameters and present quantitative meta-models of the distributions of GI transit times in the respective GI regions to help inform models of oral drug absorption. The literature was systemically reviewed for the values of, and the variability in, gastric, small intestinal and colonic transit times under fed and fasted conditions. Meta-analysis used the "metafor" package of the R language. Meta-models of GI transit were assumed to be log-normally distributed between the studied populations. Twenty-nine studies including 125 reported means and standard deviations were used in the meta-analysis. Caloric content of administered food increased variability and delayed the gastric transit of both pellets and tablets. Conversely, food caloric content reduced the variability but had no significant influence on the mean small intestinal transit time (SITT). Food had no significant effect on the transit time through the colon. The transit of pellets through the colon was significantly slower than that of single-unit tablets which is most likely related to their smaller size. GI transit times may influence the dissolution and absorption of oral drugs. The meta-models of GI transit times may be used as part of semi-physiological absorption models to characterize the influence of transit time on the dissolution, absorption and in vivo pharmacokinetic profiles of oral drugs.

  8. Characterization of the Aqueous Uranyl-Silicate Complex Using X-Ray Absorption Spectroscopy and Ab Initio Modeling

    Science.gov (United States)

    Vu, M.; Massey, M.; Huang, P.

    2015-12-01

    The speciation of aqueous uranium ions is an important factor in predicting its mobility and fate in the environment. Two major controls on speciation are pH and the presence of complexing ligands. For the case of aqueous uranyl, UO22+(aq), some common complexes include uranyl-hydroxy, uranyl-carbonato, and uranyl-calcium-carbonato complexes, all of which differ in chemical reactivity and mobility. Uranyl-silicate complexes are also known but remain poorly characterized. In this work, we studied uranyl speciation in a series of aqueous solutions of 0.1 mM uranyl and 2 mM silicate with pH ranging from 4 to 7. Extended X-Ray Absorption Fine Structure (EXAFS) spectra of these samples were recorded at the Stanford Synchrotron Radiation Lightsource (SLAC National Accelerator Laboratory). Of particular note are the uranyl and silicate concentrations employed in our experiments, which are lower than conditions in previously reported EXAFS studies and approach conditions in natural groundwater systems. Preliminary analyses of EXAFS data indicate that uranyl speciation changes across the pH range, consistent with published thermodynamic data that suggest uranyl-silicate complexes may be important for pH ~ 5 and below, while uranyl-carbonato complexes become dominant at circumneutral pH. To guide the interpretation of the EXAFS data, molecular-scale simulations were carried out using density functional theory. We considered two classes of models: (i) hydrated clusters, and (ii) ab initio molecular dynamics simulations of 3D-periodic models involving uranyl and silicate in water. These calculations reveal that at pH ~ 5, the uranyl speciation is the [UO2(H2O)4H3SiO4]+ complex formed by the substitution of an equatorial uranyl water with a monodentate silicate ligand. The evidence from experiments and simulations provide a consistent picture for the uranyl-silicate complex, which may be important in the transport of uranyl in acidic, silicate-rich waters.

  9. Characterization of intestinal absorption of C-glycoside flavonoid vicenin-2 from Lychnophora ericoides leafs in rats by nonlinear mixed effects modeling

    Directory of Open Access Journals (Sweden)

    Gabriela A. Buqui

    2015-06-01

    Full Text Available AbstractVicenin-2 (apigenin-6,8-di-C-β-d-glucopyranoside is present in hydroalcoholic extracts of the Brazilian species Lychnophora ericoides Mart., Asteraceae, leaves, and the biological effects of this compound have been demonstrated including anti-inflammatory, antioxidant and anti-tumor effects in rat models. Given the potential of this compound as a pharmacological agent, the aims of this investigation were to evaluate the extent of intestinal absorption of vicenin-2, and to determine the intestinal permeation profile using an in situ single-pass intestinal perfusion technique. A validated HPLC–UV method was applied to measure the amount of unabsorbed vicenin-2 in the gut after an oral administration of 180 mg kg-1 in five rats. A nonlinear mixed effects model was used to determine the absorption pharmacokinetic parameters assuming a first order absorption and active secretion processes for this compound, wherein the active secretion was characterized by a zero-order process. The population pharmacokinetic parameters obtained were 0.274 min-1 for the first-order absorption rate constant, 16.3% min-1 for the zero-order rate constant; the final percentage of the original dose that was absorbed in vivo was 40.2 ± 2.5%. These parameters indicated that vicenin-2 was rapidly absorbed in the small intestine. In contrast to literature information indicating no absorption of vicenin-2 in Caco-2 cells, our results suggested that vicenin-2 can be absorbed in the small intestine of rats. The finding supports further investigation of vicenin-2 as a viable oral phytopharmaceutical agent for digestive diseases.

  10. A general enhancement factor model for absorption and desorption systems: A CO2 capture case-study

    DEFF Research Database (Denmark)

    Gaspar, Jozsef; Fosbøl, Philip Loldrup

    2015-01-01

    This study derives a general method (GM) for reactive absorption and desorption calculation. It connects the Onda's approximation for reversible reactions with the van Krevelen's approach for instantaneous irreversible reactions. It is set-up for a reversible (m+n)-th order, forward reaction...

  11. The role of scattering and absorption on the optical properties of birefringent polycrystalline ceramics: Modeling and experiments on ruby (Cr:Al2O3)

    Science.gov (United States)

    Penilla, E. H.; Hardin, C. L.; Kodera, Y.; Basun, S. A.; Evans, D. R.; Garay, J. E.

    2016-01-01

    Light scattering due to birefringence has prevented the use of polycrystalline ceramics with anisotropic optical properties in applications such as laser gain media. However, continued development of processing technology has allowed for very low porosity and fine grains, significantly improving transparency and is paving the way for polycrystalline ceramics to be used in demanding optical applications. We present a method for producing highly transparent Cr3+ doped Al2O3 (ruby) using current activated pressure assisted densification. The one-step doping/densification process produces fine grained ceramics with well integrated (doped) Cr, resulting in good absorption and emission. In order to explain the light transmission properties, we extend the analytical model based on the Rayleigh-Gans-Debye approximation that has been previously used for undoped alumina to include absorption. The model presented captures reflection, scattering, and absorption phenomena in the ceramics. Comparison with measured transmission confirms that the model adequately describes the properties of polycrystalline ruby. In addition the measured emission spectra and emission lifetime are found to be similar to single crystals, confirming the high optical quality of the ceramics.

  12. Assessment and modulation of acamprosate intestinal absorption: comparative studies using in situ, in vitro (CACO-2 cell monolayers) and in vivo models.

    Science.gov (United States)

    Zornoza, Teodoro; Cano-Cebrián, María José; Nalda-Molina, Ricardo; Guerri, Consuelo; Granero, Luis; Polache, Ana

    2004-08-01

    The purpose of this study was to explore the intestinal absorption mechanism of acamprosate and to attempt to improve the bioavailability (BA) of the drug through modulation of its intestinal absorption using two enhancers (polysorbate 80 and sodium caprate) based on in situ, in vitro and in vivo models and comparing the results obtained. Intestinal transport of the drug, in the absence and in presence of polysorbate 80 (0.06, 0.28 and 9.6 mM) or sodium caprate (13 and 16 mM) was measured by using an in situ rat gut technique and Caco-2 cell monolayers. Additionally, the effect of sodium caprate on drug oral bioavailability, measured as urinary recovery, was quantified by performing in vivo experiments with the rat as animal model. Only sodium caprate was able to increase the absorption rate constant (ka) of acamprosate in the mid-intestine of the rats from 0.29 +/- 0.07 h-1 in the absence of the promoter to 0.51 +/- 0.19 h-1 in the presence of C10 16 mM, along with the apparent permeability (Papp) obtained in Caco-2 cells (around two-fold). However, the drug bioavailability in rats (around 20%) did not improve in the presence of any of the concentrations tested (13, 16 and 50 mM). It is concluded that acamprosate absorption likely occurs via paracellular pathway and can be enhanced by sodium caprate in situ and in vitro but not in vivo-thus suggesting that although in situ and in vitro studies could be useful in early screening to select a potential promoter, in vivo studies in animal models are necessary to confirm the utility of the enhancer and to determine the influence of physiological variables.

  13. Multifunctional hybrids for electromagnetic absorption

    Energy Technology Data Exchange (ETDEWEB)

    Huynen, I. [Research Center in Micro and Nanoscopic Materials and Electronic Devices, CeRMiN, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Quievy, N. [Institute of Condensed Matter and Nanosciences (IMCN), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Bailly, C. [Research Center in Micro and Nanoscopic Materials and Electronic Devices, CeRMiN, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Condensed Matter and Nanosciences (IMCN), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Mechanics, Materials and Civil Engineering (iMMC), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Bollen, P. [Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Condensed Matter and Nanosciences (IMCN), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Institute of Mechanics, Materials and Civil Engineering (iMMC), Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Detrembleur, C. [Center for Education and Research on Macromolecules (CERM), University of Liege, Sart-Tilman B6a, 4000 Liege (Belgium); Eggermont, S.; Molenberg, I. [Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Thomassin, J.M.; Urbanczyk, L. [Center for Education and Research on Macromolecules (CERM), University of Liege, Sart-Tilman B6a, 4000 Liege (Belgium)

    2011-05-15

    Highlights: > EM absorption requires low dielectric constant and {approx}1 S/m electrical conductivity. > New hybrids were processed with CNT-filled polymer foam inserted in Al honeycomb. > The EM absorption in the GHz range is superior to any known material. > A closed form model is used to guide the design of the hybrid. > The architectured material is light with potential for thermal management. - Abstract: Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over reflection in certain instances, requires combining a low dielectric constant with high electrical conductivity, which are antagonist properties in the world of materials. A novel class of hybrid materials for EM absorption in the gigahertz range has been developed based on a hierarchical architecture involving a metallic honeycomb filled with a carbon nanotube-reinforced polymer foam. The waveguide characteristics of the honeycomb combined with the performance of the foam lead to unexpectedly large EM power absorption over a wide frequency range, superior to any known material. The peak absorption frequency can be tuned by varying the shape of the honeycomb unit cell. A closed form model of the EM reflection and absorption provides a tool for the optimization of the hybrid. This designed material sets the stage for a new class of sandwich panels combining high EM absorption with mass efficiency, stiffness and thermal management.

  14. Multifunctional hybrids for electromagnetic absorption

    International Nuclear Information System (INIS)

    Highlights: → EM absorption requires low dielectric constant and ∼1 S/m electrical conductivity. → New hybrids were processed with CNT-filled polymer foam inserted in Al honeycomb. → The EM absorption in the GHz range is superior to any known material. → A closed form model is used to guide the design of the hybrid. → The architectured material is light with potential for thermal management. - Abstract: Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over reflection in certain instances, requires combining a low dielectric constant with high electrical conductivity, which are antagonist properties in the world of materials. A novel class of hybrid materials for EM absorption in the gigahertz range has been developed based on a hierarchical architecture involving a metallic honeycomb filled with a carbon nanotube-reinforced polymer foam. The waveguide characteristics of the honeycomb combined with the performance of the foam lead to unexpectedly large EM power absorption over a wide frequency range, superior to any known material. The peak absorption frequency can be tuned by varying the shape of the honeycomb unit cell. A closed form model of the EM reflection and absorption provides a tool for the optimization of the hybrid. This designed material sets the stage for a new class of sandwich panels combining high EM absorption with mass efficiency, stiffness and thermal management.

  15. [FREE CONSUMPTION OF GLUCOSE SOLUTION BY RATS AS A CRITERION FOR EVALUATION ITS ABSORPTION IN THE SMALL INTESTINE (Experimental study and mathematical modeling)].

    Science.gov (United States)

    Gruzdkov, A A; Gromova, L V; Dmitrieva, Yu V; Alekseeva, A S

    2015-06-01

    The aim of the work is to analyze the relationship between consumption of glucose solution by rats and its absorption, and to use this fact for assessment of the absorptive capacity of the small intestine in non anesthetized animals in vivo. Consumption of glucose solution (200 g/l) by fasted rats was recorded in the control, and after administration of phloridzin--inhibitor of glucose active transport- or 3 hours after the restriction stress. On the mathematical model we studied the relative role of factors that can influence the temporal dynamics of glucose consumption by rats. The rate of glucose consumption was observed being decreased in the presence of phloridzin (1 mM), and be increased after the stress. The results of modeling are consistent with the experimental data and show that the rate of consumption of glucose solutions considerably more depends on the transport activity of the small intestine than on glucose concentration in the solution, or on the substrate regulation of the stomach emptying. Analysis of dynamics of consumption of glucose solution by intact rats may be considered as one of promising approaches to assessing the absorptive capacity of the small intestine under natural conditions.

  16. Mechanism of increased iron absorption in murine model of hereditary hemochromatosis: Increased duodenal expression of the iron transporter DMT1

    OpenAIRE

    Fleming, Robert E.; Migas, Mary C.; Zhou, Xiaoyan; Jiang, Jinxing; Britton, Robert S.; Brunt, Elizabeth M.; Tomatsu, Shunji; Waheed, Abdul; Bacon, Bruce R; Sly, William S.

    1999-01-01

    Hereditary hemochromatosis (HH) is a common autosomal recessive disorder characterized by tissue iron deposition secondary to excessive dietary iron absorption. We recently reported that HFE, the protein defective in HH, was physically associated with the transferrin receptor (TfR) in duodenal crypt cells and proposed that mutations in HFE attenuate the uptake of transferrin-bound iron from plasma by duodenal crypt cells, leading to up-regulation of transporters for dietary iron. Here, we tes...

  17. Retrieval of trace gases vertical profile in the lower atmosphere combining. Differential Optical Absorption Spectroscopy with radiative transfer models

    OpenAIRE

    Palazzi, Elisa

    2008-01-01

    The motivation for the work presented in this thesis is to retrieve profile information for the atmospheric trace constituents nitrogen dioxide (NO2) and ozone (O3) in the lower troposphere from remote sensing measurements. The remote sensing technique used, referred to as Multiple AXis Differential Optical Absorption Spectroscopy (MAX-DOAS), is a recent technique that represents a significant advance on the well-established DOAS, especially for what it concerns the study of...

  18. Mesoscale modeling of photoelectrochemical devices: light absorption and carrier collection in monolithic, tandem, Si|WO3 microwires.

    Science.gov (United States)

    Fountaine, Katherine T; Atwater, Harry A

    2014-10-20

    We analyze mesoscale light absorption and carrier collection in a tandem junction photoelectrochemical device using electromagnetic simulations. The tandem device consists of silicon (E(g,Si) = 1.1 eV) and tungsten oxide (E(g,WO3) = 2.6 eV) as photocathode and photoanode materials, respectively. Specifically, we investigated Si microwires with lengths of 100 µm, and diameters of 2 µm, with a 7 µm pitch, covered vertically with 50 µm of WO3 with a thickness of 1 µm. Many geometrical variants of this prototypical tandem device were explored. For conditions of illumination with the AM 1.5G spectra, the nominal design resulted in a short circuit current density, J(SC), of 1 mA/cm(2), which is limited by the WO3 absorption. Geometrical optimization of photoanode and photocathode shape and contact material selection, enabled a three-fold increase in short circuit current density relative to the initial design via enhanced WO3 light absorption. These findings validate the usefulness of a mesoscale analysis for ascertaining optimum optoelectronic performance in photoelectrochemical devices.

  19. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    OpenAIRE

    Friese, Daniel Henrik; Bast, Radovan; Ruud, Kenneth

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon abs...

  20. Mechanistic spray dryer mathematical model based on film theory to predict sulfur dioxide absorption and reaction by a calcium hydroxide slurry in the constant rate period

    Energy Technology Data Exchange (ETDEWEB)

    Partridge, G.P. Jr.

    1987-01-01

    In the spray dryer, flue gas from a coal-fired boiler is contacted with an atomized lime slurry; during this contact SO/sub 2/ absorbs and reacts with dissolved Ca(OH)/sub 2/. The mathematical model developed in this activity superimposes SO/sub 2/ absorption and reaction phenomena on existing mathematical descriptions of spray dryer operation. The SO/sub 2/ removal appears to occur primarily in the constant rate period where a continuous liquid phase exists in the atomized slurry droplet. The constant rate period proceeds until evaporation has reduced the liquid phase volume to the point where the Ca(OH)/sub 2/ sorbent particles touch and the diffusion paths for reactants are restricted. The SO/sub 2/ absorption flux involves liquid phase as well as gas phase resistances. The liquid phase resistance includes mass transfer and chemical reaction phenomena associated with the absorption and reaction of SO/sub 2/ and Ca(OH)/sub 2/ and the dissolution of Ca(OH)/sub 2/. Instantaneous reaction occurs between SO/sub 2/ and Ca(OH)/sub 2/ in the liquid phase. Solid dissolution in the liquid film is unimportant and solid dissolution and reaction occur in series. A comprehensive model was developed for the constant rate period. The model is based on film theory and treats the atomized slurry droplet as a sphere of discrete sorbent particles with the fluid phase uniformly distributed around the individual sorbent particles. This concept allows prediction of the mass transfer coefficients and the enhancement due to increasing solids concentration as evaporation proceeds. Efficiency predicts using the model were compared with pilot plant data taken at different inlet flue gas temperatures, stoichiometric ratios and slurry flow rates.

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

    Science.gov (United States)

    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.

  2. Calculation of two-photon absorption strengths with the approximate coupled cluster singles and doubles model CC2 using the resolution-of-identity approximation.

    Science.gov (United States)

    Friese, Daniel H; Hättig, Christof; Ruud, Kenneth

    2012-01-21

    An implementation of two-photon absorption matrix elements using the approximate second-order coupled-cluster singles and doubles model CC2 is presented. In this implementation we use the resolution-of-the-identity approximation for the two-electron repulsion integrals to reduce the computational cost. To avoid storage of large arrays we introduce in addition a numerical Laplace transformation of orbital energy denominators for the response of the doubles amplitudes. The error due to the numerical Laplace transformation is found to be negligible. Using this new implementation, we performed a series of benchmark calculations on substituted benzene and azobenzene derivatives to get reference values for TD-DFT results. We show that results obtained with the Coulomb-attenuated B3LYP functional are in reasonable agreement with the coupled-cluster results, whereas other density functionals which do not have a long-range correction give considerably less accurate results. Applications to the AF240 dye molecule and a weakly bound molecular tweezer complex demonstrate that this new RI-CC2 implementation allows for the first time to compute two-photon absorption cross sections with a correlated wave function method for molecules with more than 70 atoms and to apply this method for benchmarking TD-DFT calculations on molecules which are of particular relevance for experimental studies of two-photon absorption. PMID:22130199

  3. In vitro--in silico--in vivo drug absorption model development based on mechanistic gastrointestinal simulation and artificial neural networks: nifedipine osmotic release tablets case study.

    Science.gov (United States)

    Ilić, Marija; Ðuriš, Jelena; Kovačević, Ivan; Ibrić, Svetlana; Parojčić, Jelena

    2014-10-01

    In vitro--in vivo correlations (IVIVC) are generally accepted as a valuable tool in modified release formulation development aimed at (i) quantifying the in vivo drug delivery profile and formulation related effects on absorption; (ii) establishing clinically relevant dissolution specifications and (iii) supporting the biowaiver claims. The aim of the present study was to develop relevant IVIVC models based on mechanistic gastrointestinal simulation (GIS) and artificial neural network (ANN) analysis and to evaluate their applicability and usefulness in biopharmaceutical drug characterisation. Nifedipine osmotic release tablets were selected as model drug product on the basis of their robustness, dissolution limited drug absorption and the availability of relevant literature data. Although the osmotic release tablets have been designed to be robust against the influence of physiological conditions in the gastrointestinal tract, notable differences in nifedipine dissolution kinetics were observed depending on the in vitro experimental conditions employed. The results obtained indicate that both GIS and ANN model developed were sensitive to input kinetics represented by the in vitro profiles obtained under various experimental conditions. Different in silico approaches may be successfully employed in the in vitro--in silico--in vivo model development. However, the results obtained may differ and relevant outcomes are sensitive to the methodology employed. PMID:24911992

  4. Technical note: An improved surgical model for the long-term studies of kinetics and quantification of nutrient absorption in swine.

    Science.gov (United States)

    Hooda, S; Matte, J J; Wilkinson, C W; Zijlstra, R T

    2009-06-01

    An improved technique to study kinetics and quantitative absorption of nutrients in pigs is described. Three female pigs (35 kg of BW) were surgically modified with catheters in the hepatic portal vein and carotid artery and an ultrasonic flow probe around the portal vein. Catheter placement and patency was secured using distal modifications (rings and holes) and nonabsorbable suture. Catheters and flow probe cable were tunneled subcutaneously after exteriorization for further protection. Fibrosis and adhesions in the body cavity were minimized by avoiding excessive manipulation and drying of viscera. Pigs were supported during recovery by intravenous fluid therapy of AA and electrolytes until regular feeding resumed. Catheters were flushed daily with heparinized saline (200 IU/L). After 10 d, pigs were fed a diet based on wheat and soybean meal for 6 consecutive 7-d periods. On d 7, blood was collected postprandially every 15 min from -15 to 60 min, 30 to 240 min, 60 to 480 min, and 120 to 720 min. Blood flow was measured simultaneously. Plasma was analyzed for glucose, and net glucose absorption was calculated from plasma portal-arterial differences x plasma flow [blood flow x (1 - hematocrit)]. The specific improvements for long-term use of this model are distal modifications of the catheters, postoperative treatment using parental nutrition and gut motility drug, prevention of infection of body cavity by further tunneling of catheters and blood flow probe cable, and use of ultrasonic blood flow probes and meter. Blood flow measurements using an ultrasonic blood flow probe was not changed after 52 d compared with 10 d post-surgery, indicating the reliability of this model. This catheterized pig model, thus, will allow the long-term study of the kinetics of nutrient absorption. PMID:19251919

  5. Modelling of the generation phase of an absorption cooling cycle operating intermittently; Modelisation de la phase generation d'un cycle de refrigeration par absorption solaire a fonctionnement intermittent

    Energy Technology Data Exchange (ETDEWEB)

    Boukhchana, Yasmina; Fellah, Ali; Ben Brahim, Ammar [Unite de Recherche, Thermodynamique Appliquee (99/UR/11-21), Universite de Gabes, Ecole Nationale d' ingenieurs, 6072 Gabes (Tunisia)

    2011-01-15

    No abstract prepared. [French] La modelisation en regime dynamique de la phase generation d'une installation frigorifique a absorption solaire a fonctionnement intermittent utilisant le couple ammoniac/eau a ete elaboree. L'etude basee sur l'intermittence du fonctionnement a permis d'elaborer, a travers les bilans matieres et thermiques, un modele thermodynamique reliant les temperatures, les debits et les fractions massiques dans les differents compartiments. Des journees ensoleillees representatives des quatre saisons de l'annee ont ete considerees. Les variations du taux d'ensoleillement, des temperatures et des concentrations ont ete explorees. Les resultats ont montre, moyennant les hypotheses adoptees en particulier a pression de fonctionnement constante, que la demarche proposee a permis d'avoir une temperature de generation autour de 135 C et une temperature de condensation de 60 C. Ces temperatures sont atteinte par l'adaptation de la convection naturelle a l'air pour le fonctionnement du condenseur. (orig.)

  6. Energy Absorption in a Load-Unload Cycle of Knee Implant Using Fractal Model of Rough Surfaces

    Science.gov (United States)

    Hodaei, Mohammad; Farhang, Kambiz

    2016-05-01

    Roughness measurement of knee implant surfaces is investigated. The study of roughness measurement show that the topography of knee implant surface is multi-scale and surface spectra follows a power law behavior. A magnification of rough surface topography implies that there is no difference between original and magnified profile of implant surface. For implant surface, statistical parameters such as variance of height, curvature, and slope are found to be scale-dependent. Fractal representation of implant surface shows that the size-distribution of the multi-scale contacts spots follows a power law and is characterized by the fractal dimension of implant surface. Fractal surface description of the rough surfaces of knee implant is used to obtain force-displacement relationship of the contact force. Using an approximate function through the fusion of two piecewise functions, energy absorption of a knee implant in a single cycle of load-unload is obtained.

  7. Structure of collagen adsorbed on a model implant surface resolved by polarization modulation infrared reflection-absorption spectroscopy.

    Science.gov (United States)

    Brand, Izabella; Habecker, Florian; Ahlers, Michael; Klüner, Thorsten

    2015-03-01

    The polarization modulation infrared reflection-absorption spectra of collagen adsorbed on a titania surface and quantum chemical calculations are used to describe components of the amide I mode to the protein structure at a sub-molecular level. In this study, imino acid rich and poor fragments, representing the entire collagen molecule, are taken into account. The amide I mode of the collagen triple helix is composed of three absorption bands which involve: (i) (∼1690cm(-1)) the CO stretching modes at unhydrated groups, (ii) (1655-1673cm(-1)) the CO stretching at carbonyl groups at imino acids and glycine forming intramolecular hydrogen bonds with H atoms at both NH2 and, unusual for proteins, CH2 groups at glycine at a neighbouring chain and (iii) (∼1640cm(-1)) the CO stretching at carbonyl groups forming hydrogen bonds between two, often charged, amino acids as well as hydrogen bonds to water along the entire helix. The IR spectrum of films prepared from diluted solutions (c<50μgml(-1)) corresponds to solution spectra indicating that native collagen molecules interact with water adsorbed on the titania surface. In films prepared from solutions (c⩾50μgml(-1)) collagen multilayers are formed. The amide I mode is blue-shifted by 18cm(-1), indicating that intramolecular hydrogen bonds at imino acid rich fragments are weakened. Simultaneous red-shift of the amide A mode implies that the strength of hydrogen bonds at the imino acid poor fragments increases. Theoretically predicted distortion of the collagen structure upon adsorption on the titania surface is experimentally confirmed. PMID:25498816

  8. A Quantitative Review and Meta-Models of the Variability and Factors Affecting Oral Drug Absorption-Part I: Gastrointestinal pH.

    Science.gov (United States)

    Abuhelwa, Ahmad Y; Foster, David J R; Upton, Richard N

    2016-09-01

    This study aimed to conduct a quantitative meta-analysis for the values of, and variability in, gastrointestinal (GI) pH in the different GI segments; characterize the effect of food on the values and variability in these parameters; and present quantitative meta-models of distributions of GI pH to help inform models of oral drug absorption. The literature was systemically reviewed for the values of, and the variability in, GI pH under fed and fasted conditions. The GI tract was categorized into the following 10 distinct regions: stomach (proximal, mid-distal), duodenum (proximal, mid-distal), jejunum and ileum (proximal, mid, and distal small intestine), and colon (ascending, transverse, and descending colon). Meta-analysis used the "metafor" package of the R language. The time course of postprandial stomach pH was modeled using NONMEM. Food significantly influenced the estimated meta-mean stomach and duodenal pH but had no significant influence on small intestinal and colonic pH. The time course of postprandial pH was described using an exponential model. Increased meal caloric content increased the extent and duration of postprandial gastric pH buffering. The different parts of the small intestine had significantly different pH. Colonic pH was significantly different for descending but not for ascending and transverse colon. Knowledge of GI pH is important for the formulation design of the pH-dependent dosage forms and in understanding the dissolution and absorption of orally administered drugs. The meta-models of GI pH may also be used as part of semi-physiological pharmacokinetic models to characterize the effect of GI pH on the in vivo drug release and pharmacokinetics. PMID:27495120

  9. Optical diagnostics of a surface-wave-sustained neon plasma by collisional–radiative modelling and a self-absorption method

    International Nuclear Information System (INIS)

    A surface-wave-sustained microwave discharge in a coaxial tube configuration in neon at low pressure (300–700 Pa) was studied by optical emission spectroscopy. Spectra of the discharge were analysed by a self-absorption method and a collisional–radiative model. The self-absorption method was used to determine the densities of neon metastable states. The collisional–radiative model, using these densities, was applied to determine the axially resolved electron temperature and the reduced electric field strength in the discharge from the optical spectra. Two types of electron distribution functions were used in the calculations—a Maxwellian distribution function and a solution of electron Boltzmann kinetic equation. The spatially averaged neon metastable densities were in the range (0.12–0.53) × 1016 m−3 and (3.4–4.1) × 1016 m−3 for 1s3 and 1s5 states, respectively. The axial profile of the electron temperature was found to be approximately constant around 1.3–1.6 eV depending on the pressure. The reduced electric field strength decreased along the plasma column in the range 16.5–6.0 Td depending on the pressure. A large influence of gas cooling along the plasma column on the determined reduced electric field strengths was observed. (paper)

  10. Ray-tracing and Fokker-Planck modelling of the effect of plasma current on the propagation and absorption of lower hybrid waves

    International Nuclear Information System (INIS)

    Waves at a frequency close to the lower hybrid (LH) resonance are widely used in tokamaks for non-inductive current drive. Modelling of LH waves is usually carried out by combining a Ray-tracing (RT) code for computing the LH waves propagation to a solver of the Fokker-Planck (FP) equation which calculates an electron distribution function self-consistently with the waves absorption. The DELPHINE code has been developed along this approach with accurate treatment of the magnetic equilibrium and the fast electrons dynamics in momentum space. Using this code, the influence of the plasma current on the LH waves propagation and absorption is investigated in detail. High plasma current is found to broaden the absorbed LH spectrum towards high phase velocities, thus increasing the current drive efficiency of the waves. The shape of the current density profile also has an impact on the propagation of the waves and the resulting power deposition. In discharges where the current profile is dominated by LH current drive (LHCD), this dependence leads to the auto-regulation of the LHCD via the current density profile. The RT/FP technique reproduces at least qualitatively some of the experimental trends, though inconsistencies still remain. Perspectives for improving the relevance of the modelling are discussed

  11. Line-Parameter Measurements and Stringent Tests of Line-Shape Models Based on Cavity-Enhanced Absorption Spectroscopy

    Science.gov (United States)

    Bielska, Katarzyna; Fleisher, Adam J.; Hodges, Joseph T.; Lin, Hong; Long, David A.; Reed, Zachary D.; Sironneau, Vincent; Truong, Gar-Wing; Wójtewicz, Szymon

    2014-06-01

    Laser methods that are based on cavity-enhanced absorption spectroscopy (CEAS) are well-suited for measuring molecular line parameters under conditions of low optical density, and as such they are complementary to broadband Fourier-transform spectroscopy (FTS) techniques. Attributes of CEAS include relatively low detection limits, accurate and precise detuning axes and high fidelity measurements of line shape. In many cases these performance criteria are superior to those obtained using direct laser absorption spectroscopy and FTS-based systems. In this presentation we will survey several examples of frequency-stabilized cavity ring-down spectroscopy (FS-CRDS)1 measurements obtained with laser spectrometers developed at the National Institute of Standards and Technology (NIST) in Gaithersburg Maryland. These experiments, which are motivated by atmospheric monitoring and remote-sensing applications that require high-precision and accuracy, involve nearinfrared transitions of carbon dioxide, water, oxygen and methane. We discuss spectra with signal-to-noise ratios exceeding 106, frequency axes with absolute uncertainties in the 10 kHz to 100 kHz range and linked to a Cs clock, line parameters with relative uncertainties at the 0.2 % level and isotopic ratios measured with a precision of 0.03 %. We also present FS-CRDS measurements of CO2 line intensities which are measured at atmospheric concentration levels and linked to gravimetric standards for CO2 in air, and we quantify pressure-dependent deviations between various theoretical line profiles and measured line shapes. Finally we also present recent efforts to increase data throughput and spectral coverage in CEAS experiments. We describe three new high-bandwidth CEAS techniques including frequency-agile, rapid scanning spectroscopy (FARS)2, which enables continuous-wave measurements of cavity mode linewidth and acquisition of ringdown decays with no dead time during laser frequency tuning, heterodyne

  12. Characterization of the intestinal absorption of seven flavonoids from the flowers of Trollius chinensis using the Caco-2 cell monolayer model.

    Directory of Open Access Journals (Sweden)

    Lijia Liu

    Full Text Available The human Caco-2 cell monolayer model was used to investigate the absorption property, mechanism, and structure-property relationship of seven representative flavonoids, namely, orientin, vitexin, 2"-O-β-L-galactopyranosylorientin, 2"-O-β-L-galactopyranosylvitexin, isoswertisin, isoswertiajaponin, and 2"-O-(2"'-methylbutanoylisoswertisin from the flowers of Trollius chinensis. The results showed that these flavonoids were hardly transported through the Caco-2 cell monolayer. The compounds with 7-OCH3 including isoswertisin, isoswertiajaponin and 2"-O-(2"'-methylbutanoylisoswertisin were absorbed in a passive diffusion manner, and their absorbability was increased in the same order as their polarity. The absorption of the remaining compounds with 7-OH including orientin, vitexin, 2"-O-β-L-galactopyranosylorientin, and 2"-O-β-L-galactopyranosylvitexin involved transporter mediated efflux in addition to passive diffusion. Among the four compounds with 7-OH, those with a free hydroxyl group at C-2" such as orientin and vitexin were the substrates of P-glycoprotein (P-gp and that with a free hydroxyl group at C-2' such as 2"-O-β-L-galactopyranosylorientin was the substrate of multidrug resistance protein 2 (MRP2. The results of this study also implied that the absorbability of the flavonoids should be taken into account when estimating the effective components of T. chinensis.

  13. Transport of sennosides and sennidines from Cassia angustifolia and Cassia senna across Caco-2 monolayers--an in vitro model for intestinal absorption.

    Science.gov (United States)

    Waltenberger, B; Avula, B; Ganzera, M; Khan, I A; Stuppner, H; Khan, S I

    2008-05-01

    Laxative effects of Senna preparations are mainly mediated by rheinanthrone, a metabolite formed in the intestinal flora from dianthrones. Nevertheless, it was not clear whether dianthrones are bioavailable at all and contribute to the overall effects of this important medicinal plant. Using the Caco-2 human colonic cell line as an in vitro model of the human intestinal mucosal barrier, the bioavailability of dianthrones was studied in apical to basolateral (absorptive) and basolateral to apical (secretive) direction. Permeability coefficients (P(c)) and percent transport were calculated based on quantitations by HPLC. From the data obtained it was concluded that sennosides A and B, as well as their aglycones sennidine A and B are transported through the Caco-2 monolayers in a concentration-dependent manner and their transport was linear with time. The absorption in apical to basolateral direction was poor and P(c) values were comparable to mannitol. The transport was higher in the secretory direction, indicating a significant efflux (e.g. by efflux pumps) of the (poorly) absorbed compounds in the intestinal lumen again. Our findings support the general understanding that the laxative effects of Senna are explainable mainly by metabolites and not by the natively present dianthrones.

  14. Evidence for ultra-fast outflows in radio-quiet AGNs: II - detailed photo-ionization modeling of Fe K-shell absorption lines

    CERN Document Server

    Tombesi, F; Reeves, J N; Palumbo, G G C; Braito, V; Dadina, M

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blueshifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\sim100,000km/s (\\sim0.3c), with a peak and mean value of \\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6erg s^{-1} cm, with a mean value of log\\xi 4.2 erg s^{-1} cm. The associated column densities are also large, in the range N_H\\sim10^{22}-10^{24...

  15. Assignment and modeling of the absorption spectrum of 13CH4 at 80 K in the region of the 2ν3 band (5853-6201 cm-1)

    Science.gov (United States)

    Starikova, E.; Nikitin, A. V.; Rey, M.; Tashkun, S. A.; Mondelain, D.; Kassi, S.; Campargue, A.; Tyuterev, Vl. G.

    2016-07-01

    The absorption spectrum of the 13CH4 methane isotopologue has been recently recorded by Differential Absorption Spectroscopy (DAS) at 80 K in the 5853-6201 cm-1 spectral range. An empirical list of 3717 lines was constructed for this spectral range corresponding to the upper part of the Tetradecad dominated by the 2ν3 band near 5987 cm-1. In this work, we present rovibrational analyses of these spectra obtained via two theoretical approaches. Assignments of strong and medium lines were achieved with variational calculations using ab initio potential energy (PES) and dipole moment surfaces. For further analysis a non-empirical effective Hamiltonian (EH) of the methane polyads constructed by high-order Contact Transformations (CT) from an ab initio PES was employed. Initially predicted values of EH parameters were empirically optimized using 2898 assigned line positions fitted with an rms deviation of 5×10-3 cm-1. More than 1860 measured line intensities were modeled using the effective dipole transition moments approach with the rms deviation of about 10%. These new data were used for the simultaneous fit of the 13CH4 Hamiltonian parameters of the {Ground state/Dyad/Pentad/Octad/Tetradecad} system and the dipole moment parameters of the {Ground state-Tetradecad} system. Overall, 10 vibrational states and 28 vibration sublevels of the 13CH4 Tetradecad are determined. The comparison of their energy values with corresponding theoretical calculations is discussed.

  16. An inversion model based on salinity and remote sensing reflectance for estimating the phytoplankton absorption coefficient in the Saint Lawrence Estuary

    Science.gov (United States)

    Montes-Hugo, Martin; Xie, Huxiang

    2015-10-01

    The inversion of individual inherent optical properties (IOPs) is very challenging in optically complex waters and within the violet spectral range (i.e., 380-450 nm) due to the strong light attenuation caused by chromophoric dissolved organic matter, nonalgal particulates, and phytoplankton. Here we present a technique to better discriminate light absorption contributions due to phytoplankton based on a hybrid model (QAA-hybrid) that combines regional Saint Lawrence System estimates of IOPs derived from a quasi-analytical algorithm (hereafter QAA-SLE) and empirical relationships between salinity and IOPs. Preliminary results in the Saint Lawrence System during May 2000 and April 2001 showed that QAA-hybrid estimates of phytoplankton absorption coefficient at 443 nm have a smaller bias with respect to in situ measurements (root-mean-square deviation, RMSD = 0.156) than those derived from QAA-SLE (RMSD = 0.341). These results were valid for surface waters (i.e., 0-5 m depth) of the lower estuary with a salinity and chlorophyll-a concentration range of 22-28 psu and 2.1-13.8 mg m-3, respectively.

  17. Modeling of gamma ray energy-absorption buildup factors for thermoluminescent dosimetric materials using multilayer perceptron neural network

    DEFF Research Database (Denmark)

    Kucuk, Nil; Manohara, S.R.; Hanagodimath, S.M.;

    2013-01-01

    V, and for penetration depths up to 10 mfp (mean-free-path). The MLPNNs have been trained by a Levenberg–Marquardt learning algorithm. The developed model is in 99% agreement with the ANSI/ANS-6.4.3 standard data set. Furthermore, the model is fast and does not require tremendous computational efforts. The estimated BA...

  18. VAPID: Voigt Absorption-Profile [Interstellar] Dabbler

    Science.gov (United States)

    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.

  19. The ℓ-distribution method for modeling non-gray absorption in uniform and non-uniform gaseous media

    Science.gov (United States)

    André, Frédéric

    2016-08-01

    The ℓ-distribution modeling is proposed for radiative heat transfer in uniform and non-uniform non-gray gaseous media. The method is partly based on the application of results from the k-moment method. It combines this technique with several concepts from probability theory: the notion of rank transmutation maps allows extending the k-moment method to an infinite number of k-moments; copula models appear naturally to extend the method from uniform to non-uniform gas paths. The ℓ-distribution approach is shown to provide results: (1) more accurate - up to three orders of magnitude - than usual k-distribution approaches in uniform media, (2) as precise as correlated-k models in non-uniform situations. All these results are obtained at a computational cost lower than k-distribution models. Differences and similarities between k- and ℓ-distribution methods are discussed.

  20. Atomic Calculations and Spectral Models of X-ray Absorption and Emission Features From Astrophysical Photoionized Plasmas

    CERN Document Server

    Kinkhabwala, A; Sako, M; Gu, M F; Kahn, S M; Paerels, F B S

    2003-01-01

    We present a detailed model of the discrete X-ray spectroscopic features expected from steady-state, low-density photoionized plasmas. We apply the Flexible Atomic Code (FAC) to calculate all of the necessary atomic data for the full range of ions relevant for the X-ray regime. These calculations have been incorporated into a simple model of a cone of ions irradiated by a point source located at its tip (now available as the XSPEC model PHOTOION). For each ionic species in the cone, photoionization is balanced by recombination and ensuing radiative cascades, and photoexcitation of resonance transitions is balanced by radiative decay. This simple model is useful for diagnosing X-ray emission mechanisms, determining photoionization/photoexcitation/recombination rates, fitting temperatures and ionic emission measures, and probing geometrical properties (covering factor/column densities/radial filling factor/velocity distributions) of absorbing/reemitting regions in photoionized plasmas. Such plasmas have already...

  1. Self-consistent particle-in-cell modelling of short pulse absorption and transport for high energy density physics experiments

    Science.gov (United States)

    Ramsay, M. G.; Arber, T. D.; Sircombe, N. J.

    2016-03-01

    In order for detailed, solid density particle-in-cell (PIC) simulations to run within a reasonable time frame, novel approaches to modelling high density material must be employed. For the purposes of modelling high intensity, short pulse laser-plasma interactions, however, these approaches must be consistent with retaining a full PIC model in the low-density laser interaction region. By replacing the standard Maxwell field solver with an electric field update based on a simplified Ohm's law in regions of high electron density, it is possible to access densities at and above solid without being subject to the standard grid and time step constraints. Such a model has recently been implemented in the PIC code EPOCH. We present the initial results of a detailed two-dimensional simulation performed to compare the adapted version of the code with recent experimental results from the Orion laser facility.

  2. Property profiling of biosimilar mucus in a novel mucus-containing in vitro model for assessment of intestinal drug absorption

    DEFF Research Database (Denmark)

    Bøgh, Marie; Baldursdóttir, Stefania G; Müllertz, Anette;

    2014-01-01

    comparable to freshly isolated porcine intestinal mucus (PIM). Further, this multicomponent biosimilar mucus mixture was optimized with regards to the lipid content in order to obtain cellular biocompatibility with well-differentiated Caco-2 cell monolayers. In contrast, PIM was found to severely disrupt...... of the biorelevance of the Caco-2 cell culture model by application of mucus, resulting in an in vitro model of oral mucosa suitable for future assessment of innovative drug delivery approaches....

  3. Pion absorption processes

    International Nuclear Information System (INIS)

    Proton and deuteron production from low-energy pion absorption in light nuclei leading to discrete and continuum states were measured. The LEP beam line at LAMPF was used with a stack of 8 intrinsic germanium crystals. The proton energy spectra are in general characterized by a broad bump at an energy approximately corresponding to π+d → pp reaction kinematics, suggestive of pion absorption on 2 nucleons. The energy-integrated cross-section for production of deuterons has an angular distribution similar to that for production of protons. The dependence of the total pion absorption cross-section on A is explained using a semi-classical model for pion transport in nuclei. The (π+,p) as well as (π+,d) reactions generally favor transitions involving larger angular momentum transfer to the residual nucleus when states of similar nuclear structure are considered. The low-energy excitation spectra from the (π+,p) reaction are similar to the spectra from (p,d) reaction on 12C and 13C. However, a calculation of the (π+,p) cross-section using the measured (p,d) reaction with the formulation of Wilkin to relate the two reactions is in moderate disagreement with the measured (π+,p) cross-sections. The excitation spectra from the (π+,p) reaction indicte the importance of two-step processes for the reaction. The (π+,d) reaction leading to the ground state of -- residual nucleus has been seen for 7Li, 12C, and 13C targets. The measured cross section for the 12C(π+,d)10C reaction to the 2+ state is much higher than that for the ground state. For the case of 18O, no counts were seen for excitation energy of +,d) reaction

  4. The CAESAR project: Experimental and modeling investigations of methane reforming in a CAtalytically Enhanced Solar Absorption Receiver on a parabolic dish

    Energy Technology Data Exchange (ETDEWEB)

    Muir, J.F.; Hogan, R.E. Jr.; Skocypec, R.D. [Sandia National Labs., Albuquerque, NM (US); Buck, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt, Stuttgart (DE). Inst. of Technical Thermodynamics

    1993-07-01

    A joint US/Federal Republic of Germany (FRG) project has successfully tested a unique solar-driven chemical reactor in the CAtalytically Enhanced Solar Absorption Receiver (CAESAR) experiment. The CAESAR test was a {open_quotes}proof-of-concept{close_quotes} demonstration of carbon-dioxide reforming of methane in a commercial-scale, solar, volumetric receiver/reactor on a parabolic dish concentrator. The CAESAR design; test facility and instrumentation; thermal and chemical tests; and analysis of test results are presented in detail. Numerical models for the absorber and the receiver are developed and predicted performance is compared with test data. Post test analyses to assess the structural condition of the absorber and the effectiveness of the rhodium catalyst are presented. Unresolved technical issues are identified and future development efforts are recommended.

  5. Modeling of Artificial Neural Network for Predicting Specific Heat capacity of working fluid LiBr-H2O used in Vapor Absorption Refrigeration System

    Directory of Open Access Journals (Sweden)

    Dheerendra Vikram Singh

    2011-05-01

    Full Text Available The objective of this work is to model an artificial neural network (ANN to predict the value of specific heat capacity of working fluid LiBr-H2O used in vapour absorption refrigeration systems. A feed forward back propagation algorithm is used for the network, which is most popular for ANN. The consistence between experimental and ANN’s approach result was achieved by a mean relative error -0.00573, sum of the squares due to error0.00321, coefficient of multiple determination R-square 0.99961and root mean square error 0.01573 for test data. These results had been achieved in Matlab environment and the use of derived equations in any programmable language for deriving the specific heat capacity of LiBr-H2O solution.

  6. The CAESAR project: Experimental and modeling investigations of methane reforming in a catalytically enhanced solar absorption receiver on a parabolic dish

    Science.gov (United States)

    Muir, J. F.; Hogan, R. E., Jr.; Skocypec, R. D.; Buck, R.

    1993-07-01

    A joint US/Federal Republic of Germany (FRG) project has successfully tested a unique solar-driven chemical reactor in the Catalytically Enhanced Solar Absorption Receiver (CAESAR) experiment. The CAESAR test was a proof-of-concept demonstration of carbon-dioxide reforming of methane in a commercial-scale, solar, volumetric receiver/reactor on a parabolic dish concentrator. The CAESAR design, test facility and instrumentation, thermal and chemical tests, and analysis of test results are presented in detail. Numerical models for the absorber and the receiver are developed and predicted performance is compared with test data. Post test analyses to assess the structural condition of the absorber and the effectiveness of the rhodium catalyst are presented. Unresolved technical issues are identified and future development efforts are recommended.

  7. D-xylose absorption

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  8. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model.

    Science.gov (United States)

    Seim, Gretchen L; Ahn, Cedric I; Bodis, Mary S; Luwedde, Flavia; Miller, Dennis D; Hillier, Stephen; Tako, Elad; Glahn, Raymond P; Young, Sera L

    2013-08-01

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested these hypotheses by measuring Fe concentration and relative bioavailable Fe content of 12 samples of geophagic earth and 4 samples of pure clay minerals. Further, we assessed the impact of these samples on the bioavailability of Fe from an Fe-rich test meal (cooked white beans, WB). Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability was determined using an in vitro digestion/Caco-2 cell model in which ferritin formation was used as an index of Fe bioavailability. Geophagic earth and clay mineral samples were evaluated with this model, both alone and in combination with WB (1 : 16 ratio, sample : WB). Median Fe concentration of the geophagic earth was 3485 (IQR 2462, 14 ,571) μg g⁻¹ and mean Fe concentration in the clay minerals was 2791 (±1782) μg g⁻¹. All specimens had Fe concentrations significantly higher (p ≤ 0.005) than the Fe concentration of WB (77 μg g⁻¹). Ferritin formation (i.e. Fe uptake) in cells exposed to geophagic earths and clay minerals was significantly lower than in cells exposed to WB (p ≤ 0.05) and Fe uptake responses of 11 of the 16 samples were not significantly different from the blank, indicating no bioavailable Fe. When samples were combined with WB, 5 of 16 had mean ferritin levels that were significantly lower (p ≤ 0.05, one tail) than the WB alone, indicating that the samples inhibited Fe uptake from the WB. None of the ferritin responses of cells exposed to both WB and earth/clay were significantly higher than WB alone. Thus, although geophagic earths and mineral clays are high in total Fe, very little of this Fe is bioavailable. Further, some

  9. Progress of mathematical modeling for trandermal drug absorption%药物经皮吸收数学模型研究进展

    Institute of Scientific and Technical Information of China (English)

    何星篧; 王晖

    2015-01-01

    Transdermal drug delivery is an administration route which can avoid the first-pass effect,maintain steady plasma concentrations and enhance bioavailability. Drug transporting through the skin by passage through the stratum corneum leads to the viable epidermis and the dermis.With the development of the computer technology,many mathematical models for predic-ting the absorption of drugs have been built according to physical and chemical properties of drugs and physiological characteristics of each skin layer.This article presented provides a summary of the progress of mathematical models for predicting percutaneous absorption of drugs.%经皮给药是一种能避免肝脏的首过效应及肠胃灭活、维持血药浓度、提高生物利用度的给药途径。而药物经皮吸收需透过角质层、活性表皮层、真皮层的屏障。近年来,随着计算机技术的发展,根据药物的不同理化特性及皮肤各层的生理特征,建立了许多预测药物经皮吸收方面的数学模型。该文就预测药物经皮吸收数学模型的研究进展进行了综述。

  10. Efficacy of skin wash on dermal absorption: an in vitro study on four model compounds of varying solubility

    DEFF Research Database (Denmark)

    Nielsen, Jesper Bo

    2010-01-01

    PURPOSE: Following dermal exposure to chemicals causing systemic toxicity, the general advice to avoid further systemic exposure is to wash the skin. The present study uses four model compounds (benzoic acid, glyphosat, caffeine, malathion) with varying size and solubility to substantiate...... this advice and quantify the effect of skin wash following 6 h dermal exposure on subsequent extent of skin penetration and deposition within the skin compartment. METHOD: Percutaneous penetration through human skin is studied in an in vitro model with static diffusion cells. RESULTS: The study demonstrates...

  11. Lyman-alpha Absorption from Heliosheath Neutrals

    CERN Document Server

    Wood, B E; Linsky, J L; Malama, Y G; Wood, Brian E.; Izmodenov, Vladislav V.; Linsky, Jeffrey L.; Malama, Yury G.

    2006-01-01

    We assess what information HST observations of stellar Ly-alpha lines can provide on the heliosheath, the region of the heliosphere between the termination shock and heliopause. To search for evidence of heliosheath absorption, we conduct a systematic inspection of stellar Ly-alpha lines reconstructed after correcting for ISM absorption (and heliospheric/astrospheric absorption, if present). Most of the stellar lines are well centered on the stellar radial velocity, as expected, but the three lines of sight with the most downwind orientations relative to the ISM flow (Chi1 Ori, HD 28205, and HD 28568) have significantly blueshifted Ly-alpha lines. Since it is in downwind directions where heliosheath absorption should be strongest, the blueshifts are almost certainly caused by previously undetected heliosheath absorption. We make an initial comparison between the heliosheath absorption and the predictions of a pair of heliospheric models. A model with a complex multi-component treatment of plasma within the he...

  12. MATHEMATICAL MODEL OF AN OPTICAL ENERGY ABSORPTION MODULE OF INTEGRATED SYSTEM OFF-LANE POWER HEATING SUPPLY OF AGRICULTURAL PRODUCTION

    Directory of Open Access Journals (Sweden)

    Gazalov V. S.

    2014-10-01

    Full Text Available We have made energy estimation of absorbed solar fluxes with a glance of diffuse insolation which passes through double- glazing unit to the right-angled planar radiator. While designing the model it was conceded to assume that direct solar radiation is the radiation of a point source

  13. 8-band k·p modelling of mid-infrared intersubband absorption in Ge quantum wells

    Science.gov (United States)

    Paul, D. J.

    2016-07-01

    The 8-band k.p parameters which include the direct band coupling between the conduction and the valence bands are derived and used to model optical intersubband transitions in Ge quantum well heterostructure material grown on Si substrates. Whilst for Si rich quantum wells the coupling between the conduction bands and valence bands is not important for accurate modelling, the present work demonstrates that the inclusion of such coupling is essential to accurately determine intersubband transitions between hole states in Ge and Ge-rich Si1-xGex quantum wells. This is due to the direct bandgap being far smaller in energy in Ge compared to Si. Compositional bowing parameters for a range of the key modelling input parameters required for Ge/SiGe heterostructures, including the Kane matrix elements, the effective mass of the Γ 2 ' conduction band, and the Dresselhaus parameters for both 6- and 8-band k.p modelling, have been determined. These have been used to understand valence band intersubband transitions in a range of Ge quantum well intersubband photodetector devices in the mid-infrared wavelength range.

  14. Canopy Light Absorption and Application of the Light-Use Efficiency Model of Photosynthesis in a Northern Great Plains Grassland

    Science.gov (United States)

    Flanagan, L. B.; Sharp, E. J.; Gamon, J. A.

    2014-12-01

    The fraction of absorbed photosynthetically active radiation (fAPAR) is fundamentally important for model calculations of ecosystem productivity across large areas. The main objective of this study was to better understand factors influencing fAPAR, its relationship with seasonal variation in canopy greenness (Normalized Difference Vegetation Index (NDVI)), and the consequences of potential seasonal changes in the NDVI- fAPAR relationship for light-use efficiency model calculations of ecosystem photosynthesis in a semi-arid grassland. We used two approaches to determine fAPAR, (i) incoming and outgoing radiance measurements above and below the canopy, and (ii) an inversion approach based on incident photosynthetically active radiation and the light response curve of net ecosystem productivity (NEP) measured by eddy covariance at low light levels. The two approaches resulted in fAPAR values that were very strongly correlated during the initial development of the canopy until peak leaf area index (LAI) was reached. A strong linear relationship also occurred between fAPAR and NDVI, based on reflectance measurements made along a tram system above the grassland canopy during initial LAI development. After peak LAI, there was hysteresis in the NDVI- fAPAR relationship. Light-use efficiency model calculations of ecosystem photosynthesis made using fAPAR values were strongly correlated with chamber CO2 exchange measurements during the initial development of the canopy leaf area. After peak LAI, a relative stress function, based on either soil moisture or vapour pressure deficit (VPD) measurements, was necessary to reduce quantum yield and model calculations of ecosystem photosynthesis during periods of relatively low soil moisture and higher VPD later in the growing season. Both stress functions were similarly effective in improving the correlation between modeled and measured ecosystem photosynthesis values.

  15. Aspects on modeled and the design of a system of refrigeration by absorption attended with solar energy; Aspectos sobre el modelado y diseno de un sistema de refrigeracion por absorcion asistido con energia solar

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Cascales, J. R.; Vera Garcia, F.; Cano Izquierdo, J. M.; Delgado Marin, J. P.; Martinez Sanchez, R.

    2008-07-01

    In this paper, we study the global modelling of an absorption system working with Br Li-H{sub 2}O. It satisfies the air-conditioning necessities of a classroom in an educational centre in Puerto Lumbreras. Murcia. This system utilises a set of solar collector to satisfy the thermal necessities of the vapour generator in the absorption system. For the dynamical simulation of the system we have used the TRNSYS software. The air-conditioned place has been modelled by using a TRNSYS module called PREBID. In this work, special attention is paid to the absorption equipment model developed by using neural networks which has been implemented in TRNSYS. The paper is closed drawing some conclusions. (Author)

  16. Absorption of calcium ions on oxidized graphene sheets and study its dynamic behavior by kinetic and isothermal models

    Science.gov (United States)

    Fathy, Mahmoud; Abdel Moghny, Th.; Mousa, Mahmoud Ahmed; El-Bellihi, Abdel-Hameed A.-A.; Awadallah, Ahmed E.

    2016-07-01

    Sorption of calcium ion from the hard underground water using novel oxidized graphene (GO) sheets was studied in this paper. Physicochemical properties and microstructure of graphene sheets were investigated using Raman spectrometer, thermogravimetry analyzer, transmission electron microscope, scanning electron microscope. The kinetics adsorption of calcium on graphene oxide sheets was examined using Lagergren first and second orders. The results show that the Lagergren second-order was the best-fit model that suggests the conception process of calcium ion adsorption on the Go sheets. For isothermal studies, the Langmuir and Freundlich isotherm models were used at temperatures ranging between 283 and 313 K. Thermodynamic parameters resolved at 283, 298 and 313 K indicating that the GO adsorption was exothermic spontaneous process. Finally, the graphene sheets show high partiality toward calcium particles and it will be useful in softening and treatment of hard water.

  17. Modeling and simulation of a 100 kWe HT-PEMFC subsystem integrated with an absorption chiller subsystem

    DEFF Research Database (Denmark)

    Arsalis, Alexandros

    2012-01-01

    system components are described and analyzed in detail, in terms of modeling assumptions and configuration topology. The results show the high technical potential of the proposed sys¬tem, since high net electrical efficiencies are accomplished. The calculated net electrical efficiency is 43.8% for a net...... systems, i.e., diesel engines integrated with vapor-compression chillers, and therefore justifies further development of the proposed system....

  18. Electromodulated absorption in smoky quartz

    NARCIS (Netherlands)

    Brom, W.E. van den; Volger, J.

    1974-01-01

    The optical absorption coefficient of “smoky” quartz (containing aluminium) can be modulated by applying an electric field. The effect saturates at high fields and low temperatures and reaches a maximum at 535 nm. The results are discussed in terms of a model consisting of a colour centre, dipolar i

  19. Mantle formation, coagulation and the origin of cloud/core shine: I. Modelling dust scattering and absorption in the infra-red

    CERN Document Server

    Jones, A P; Ysard, N; Dartois, E; Godard, M; Gavilan, L

    2016-01-01

    Context. The observed cloudshine and coreshine (C-shine) have been explained in terms of grain growth leading to enhanced scatter- ing from clouds in the J, H and K photometric bands and the Spitzer IRAC 3.6 and 4.5 {\\mu}m bands. Aims. Using our global dust modelling approach THEMIS (The Heterogeneous dust Evolution Model at the IaS) we explore the effects of dust evolution in dense clouds, through aliphatic-rich carbonaceous mantle formation and grain-grain coagulation. Methods. We model the effects of wide band gap a-C:H mantle formation and the low-level aggregation of diffuse interstellar medium dust in the moderately-extinguished outer regions of molecular clouds. Results. The formation of wide band gap a-C:H mantles on amorphous silicate and amorphous carbon (a-C) grains leads to a decrease in their absorption cross-sections but no change in their scattering cross-sections at near-IR wavelengths, resulting in higher albedos. Conclusions. The evolution of dust, with increasing density and extinction in t...

  20. Thermal modeling of a secondary concentrator integrated with an open direct-absorption molten-salt volumetric receiver in a beam-down tower system

    Science.gov (United States)

    Lahlou, Radia; Armstrong, Peter; Grange, Benjamin; Almheiri, Saif; Calvet, Nicolas; Slocum, Alexander; Shamim, Tariq

    2016-05-01

    An upward-facing three-dimensional secondary concentrator, herein termed Final Optical Element (FOE), is designed to be used in a beam-down tower in combination with an open volumetric direct-absorption molten-salt receiver tank acting simultaneously as a thermal energy storage system. It allows reducing thermal losses from the open receiver by decreasing its aperture area while keeping minimal spillage losses. The FOE is exposed to high solar fluxes, a part of which is absorbed by its reflector material, leading to material degradation by overheating. Consequently, the FOE may require active cooling. A thermal model of the FOE under passive cooling mechanism is proposed as a first step to evaluate its sensitivity to some design parameters. Then, it will be used to evaluate the requirements for the active cooling system. The model provides insights on the FOE thermal behavior and highlights the effectiveness of a design modification on passive cooling enhancement. First prototype tests under reduced flux and with no active cooling will be used for model adjustment.

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

    Science.gov (United States)

    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.

  2. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  3. Synchrotron radiation and long path cryogenic cells: New tools and results for modelling SF6 absorption in the 10μm atmospheric window

    Science.gov (United States)

    Faye, Mbaye; Boudon, Vincent; Loete, Michel; Roy, Pascale; Manceron, Laurent

    2015-04-01

    Sulfur hexa?uoride (SF6) is a heavy and stable molecule used in many sectors, such as the electrical industry, but also as a gas tracer to model air masse motions in the Earth atmosphere. This anthropogenic species is also an atmospheric pollutant owing to its greenhouse effect capability. Although its six fundamental modes have been largely studied up to now, it is not the case for the numerous hot bands that represent the most important part of the SF6 spectrum at room temperature. So, to model correctly the SF6 atmospheric absorption requires the knowledge of the spectroscopic parameters of all states involved in these hot bands. Nevertheless, due to their overlapping, a direct analysis of the hot bands near the 10,5μm absorption of SF6 in the atmospheric window is not possible. It is necessary to use another strategy, gathering information in the far and mid infrared regions on initial and final states to recompute the relevant total absorption. Here, we present new results of an analysis of spectra recorded at the AILES beam line at the SOLEIL Synchrotron facility. For these measurements, we used a IFS125HR interferometer in the 100 - 3200 cm-1 range, coupled to a cryogenic multiple pass cell [1]. The optical path length was adjusted to 93m; the SF6 sample was cooled down to 153 K. We could record 17 rovibrational bands of SF6 in this region with a resolution of 0.0025 cm-1. These results allowed us to perform the detailed analysis of several bands. Adding to previous knowledge on ν3, ν2, 2ν3 and new results on 3ν3, 2ν1 + ν3, ν1 + ν3, ν2 + ν3, ν3 - ν2 , ν3 - ν1 , we developed a global fit of the ν1, ν2, ν3 parameters, thus permitting the modelling of the ν3 + ν1 - ν1, ν3 + ν2 - ν2 hot bands. New information has also been obtained on ν6 and ν3 + ν5 and another strategy will be detailed to model the more important ν3 + ν5 - ν5 and ν3 + ν6 - ν6 hot band contributions. Including these new parameters in the XTDS model [2], we

  4. Solar powered absorption air conditioning

    Science.gov (United States)

    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.

  5. Modelling the Emission And/or Absorption Features in the High Resolution Spectra of the Southern Binary System: HH Car

    Science.gov (United States)

    Koseoglu, Dogan; Bakış, Hicran

    2016-07-01

    High-resolution spectra (R=48000) of the southern close binary system, HH Car, has been analyzed with modern analysis techniques. Precise absolute parameters were derived from the simultaneous solution of the radial velocity, produced in this study and the light curves, published. According to the results of these analyses, the primary component is an O9 type main sequence star while the secondary component is a giant/subgiant star with a spectral type of B0. Hα emissions can be seen explicitly in the spectra of HH Car. These features were modelled using the absolute parameters of the components. Since components of HH Car are massive early-type stars, mass loss through stellar winds can be expected. This study revealed that the components of HH Car have stellar winds and the secondary component loses mass to the primary. Stellar winds and the gas stream between the components were modelled as a hot shell around the system. It is determined that the interaction between the winds and the gas stream leads to formation of a high temperature impact region.

  6. 1-d model for propagation and absorption of h.f. waves near ion cyclotron resonances in large tokamak plasmas

    International Nuclear Information System (INIS)

    The behaviour of h.f. waves near ion cyclotron and ion ion hybrid resonances in a tokamak is investigated by means of an one-dimensional finite element code. Our model takes into account: - strength and orientation of the poloidal component of the static magnetic field, - finite larmor radius corrections to the dielectric tensor, - ion cyclotron damping at the fundamental and first harmonic resonance, - electron Landau damping to lowest order msub(e)/msub(i). We assume that an incoming fast wave approaches the singular layer from the low or high field side making an arbitrary angle relative to the local magnetic flux surface and to the resonance layer. These initial conditions might be provided by ray tracing from the antenna. Then we calculate the electromagnetic wavefield and the power fluxes of the transmitted or reflected fast and slow waves as well as the power absorbed by ions and electrons. (orig.)

  7. Variability of calcium absorption

    International Nuclear Information System (INIS)

    Variability in calcium absorption was estimated in three groups of normal subjects in whom Ca absorption was measured by standard isotopic-tracer methods at interstudy intervals ranging from 1 to 4 mo. Fifty absorption tests were performed in 22 subjects. Each was done in the morning after an overnight fast with an identical standard breakfast containing a Ca load of approximately 250 mg. Individual fractional absorption values were normalized to permit pooling of the data. The coefficient of variation (CVs) for absorption for the three groups ranged from 10.57 to 12.79% with the size of the CV increasing with interstudy duration. One other published study presenting replicate absorption values was analyzed in a similar fashion and was found to have a CV of absorption of 9.78%. From these data we estimate that when the standard double-isotope method is used to measure Ca absorption there is approximately 10% variability around any given absorption value within an individual human subject and that roughly two-thirds of this represents real biological variability in absorption

  8. Reactive species output of a plasma jet with a shielding gas device—combination of FTIR absorption spectroscopy and gas phase modelling

    International Nuclear Information System (INIS)

    In this work, a simple modelling approach combined with absorption spectroscopy of long living species generated by a cold atmospheric plasma jet yields insight into relevant gas phase chemistry. The reactive species output of the plasma jet is controlled using a shielding gas device. The shielding gas is varied using mixtures of oxygen and nitrogen at various humidity levels. Through the combination of Fourier transform infrared (FTIR) spectroscopy, computational fluid dynamics (CFD) simulations and zero dimensional kinetic modelling of the gas phase chemistry, insight into the underlying reaction mechanisms is gained. While the FTIR measurements yield absolute densities of ozone and nitrogen dioxide in the far field of the jet, the kinetic simulations give additional information on reaction pathways. The simulation is fitted to the experimentally obtained data, using the CFD simulations of the experimental setup to estimate the correct evaluation time for the kinetic simulation. It is shown that the ozone production of the plasma jet continuously rises with the oxygen content in the shielding gas, while it significantly drops as humidity is increased. The production of nitrogen dioxide reaches its maximum at about 30% oxygen content in the shielding gas. The underlying mechanisms are discussed based on the simulation results. (paper)

  9. 模型混响室与音质模型试验中座椅吸声取值的实验研究%Experimental Study on Model Reverberation Chamber and Seat Absorption Value in Model Test

    Institute of Scientific and Technical Information of China (English)

    冯善勇

    2013-01-01

    Scale model test is an important method to predict the status of building acoustics; select the appropriate scale seat is an important part of the test. In theory, in order to ensure the accuracy of the test, the absorption properties of the interface in scale model should be fully consistent with the sound absorption characteristics of actual hall. But in practical application, it is difficult to achieve this point. From the point of the effectiveness and accuracy, through the large number of the actual measurement, analysis of the existing problems in the test method, to provide scientific basis for determining the seat absorption value in model test.%缩尺模型试验是预测厅堂音质状况的一个重要方法,而选取符合吸声要求的缩尺座椅则是该试验的重要组成部分。从理论上讲,为了保证试验的准确性,缩尺模型中相应界面的吸声特性应与实际厅堂内各界面吸声特性完全一致。但在实际应用中,并不能完全做到这一点。从测量的有效性和准确性角度出发,通过大量的实际测量,分析研究整个试验方法中厅堂座席吸声取值存在的问题,为科学确定音质模型中的座椅吸声取值提供评判依据。

  10. INTEGRATION OF NPP SEMI MECHANISTIC - MODELLING, REMOTE SENSING AND CIS IN ESTIMATING CO 2 ABSORPTION OF FOREST VEGETATION IN LORE LINDU NATIONAL PARK

    Directory of Open Access Journals (Sweden)

    GODE GRAVENHORsr

    2006-01-01

    Full Text Available Net Primary Production, NPP, is one of the most important variables characterizing the performance of an ecosystem. It is the difference between the total carbon uptake from the air through photosynthesis and the carbon loss due to respiration by living plants. However, field measurements of NPP are time-consuming and expensive. Current techniques are therefore not useful for obtaining NPP estimates over large areas. By combining the remote sensing and GIS technology and modelling, we can estimate NPP of a large ecosystem with a little ease. This paper discusses the use of a process based physiological sunshade canopy models in estimating NPP of Lore Lindu National Park (LLNP. The discussion includes on how to parameterize the models and how to scale up from leaf to the canopy. The version documented in this manuscript is called NetPro Model, which is a potential NPP model where water effect is not included yet. The model integrates CIS and the use of Remote Sensing, and written in Visual Basic 6.0 programming language and Map Objects 2.1. NetPro has the capability of estimating NPP of Cs vegetation under present environmental condition and under future scenarios (increasing [CO2], increasing temperature and increasing or decreasing leaf nitrogen level. Based on site-measured parameterisation of VaM* (Photosynthetic capacity, /Jj (Respiration and leaf nitrogen ONi, the model was run under increasing CO2 level and temperature and varied leaf nitrogen. The output of the semi-mechanistic modelling is radiation use efficiency (?. Analysis of remote sensing data give Normalized Difference Vegetation Index (NDVI and related Leaf Area Index (LAI and traction of absorbed Photosynthetically Active Radiation (/M > AK. Climate data are obtained from 12 meteorological stations around die parks, which includes global radiations, minimum and maximum temperature. CO2 absorbed by vegetation (Gross Primary Production, GPP is then calculated using the above

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

    Science.gov (United States)

    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.

  12. Modeling and numerical simulation of a novel solar-powered absorption air conditioning system driven by a bubble pump with energy storage

    Institute of Scientific and Technical Information of China (English)

    QIU Jia; LIANG Jian; CHEN GuangMing; DU RuXu

    2009-01-01

    This paper presents a novel solar-powered absorption air conditioning system driven by a bubble pump with energy storage. It solves the problem of unreliable solar energy supply by storing the working fluids and hence, functions 24 h per day. First, the working principles are described and the dynamic models for the primary energy storage components are developed. Then, the system is evaluated based on a numerical simulation. Based on the meteorological data of a typical day in a subtropical area, with the area of a solar collector being set at 19.15 m2, whilst the initial charging mass, mass fraction and temperature of the solution are respectively set at 379.5 kg, 54.16% and 34.5 ℃, it is found that the respective coefficients of performance (COP) of the air conditioning system and the en-tire system (including the solar panel) are 0.7771 and 0.4372. In particular, the energy storage density of the system is 206.69 MJ/m3 which is much greater than those of chilled water or hot water storage systems under comparable conditions. This makes the new system much more compact and efficient. Finally, an automatic control strategy is given to achieve the highest COP when solar energy fluctuates.

  13. Enhancing Green Absorptive Capacity, Green Dynamic Capacities and Green Service Innovation to Improve Firm Performance: An Analysis of Structural Equation Modeling (SEM

    Directory of Open Access Journals (Sweden)

    Yu-Shan Chen

    2015-11-01

    Full Text Available This study discusses the influences of green absorptive capacity, green dynamic capacities, and green service innovation on firm performance. In order to fill the research gap, this study proposes the concept of green service innovation. The results are as follows: First, this study finds that green absorptive capacity has positive effects on green dynamic capacities, green service innovation, and firm performance. Second, this study points out that green dynamic capacities have positive effects on green service innovation and firm performance. Third, this study observes that green dynamic capacities and green service innovation intercede the positive connection between green absorptive capacity and firm performance.

  14. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

    Science.gov (United States)

    Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets.

  15. Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-11-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outflow velocity higher than 10,000 km s-1 and assessed the statistical significance of the associated blueshifted absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. The present paper is an extension of that work. First, we report a detailed curve of growth analysis of the main Fe XXV/XXVI transitions in photoionized plasmas. Then, we estimate an average spectral energy distribution for the sample sources and directly model the Fe K absorbers in the XMM-Newton spectra with the detailed Xstar photoionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35% and that the majority of the Fe K absorbers are indeed associated with UFOs. The outflow velocity distribution spans from ~10,000 km s-1 (~0.03c) up to ~100,000 km s-1 (~0.3c), with a peak and mean value of ~42,000 km s-1 (~0.14c). The ionization parameter is very high and in the range log ξ ~ 3-6 erg s-1 cm, with a mean value of log ξ ~ 4.2 erg s-1 cm. The associated column densities are also large, in the range N H ~ 1022-1024 cm-2, with a mean value of N H ~ 1023 cm-2. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7 keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton-thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can

  16. Absorption of volatile ruthenium

    International Nuclear Information System (INIS)

    Phase equilibrium and mass transfer measurements for the absorption of ruthenium tetroxide (RuO4) in aqueous and nitric acid solutions have been completed. Low concentration phase equilibrium measurements confirm that the system obeys Henry's law across 4 orders of magnitude in concentration. Mass transfer measurements from turbulent gas flow indicate that the diffusivity of RuO4 in air may increase slightly as its concentration is reduced by 5-6 orders of magnitude. The reaction of RuO4 with nitrous acid and nitrites in solution results in precipitated or colloidal RuO2. Initial, immediate decomposition of ∼ 50% of the RuO4 occurs at RuO4: HNO2 mole ratios between 10:1 and 1:2, and does not vary systematically with mole ratio in this range. A mathematical model of the RuO4 decontamination performance of a packed bed scrubber has been developed, and validated experimentally with a laboratory QVF system. A survey of modelling approaches for predicting the ruthenium decontamination performance of off-gas condensers has been carried out. (author)

  17. Nutrition and magnesium absorption.

    NARCIS (Netherlands)

    Brink, E.J.

    1992-01-01

    The influence of various nutrients present in dairy products and soybean-based products on absorption of magnesium has been investigated. The studies demonstrate that soybean protein versus casein lowers apparent magnesium absorption in rats through its phytate component. However, true magnesium abs

  18. Enhancing Green Absorptive Capacity, Green Dynamic Capacities and Green Service Innovation to Improve Firm Performance: An Analysis of Structural Equation Modeling (SEM)

    OpenAIRE

    Yu-Shan Chen; Yu-Hsien Lin; Ching-Ying Lin; Chih-Wei Chang

    2015-01-01

    This study discusses the influences of green absorptive capacity, green dynamic capacities, and green service innovation on firm performance. In order to fill the research gap, this study proposes the concept of green service innovation. The results are as follows: First, this study finds that green absorptive capacity has positive effects on green dynamic capacities, green service innovation, and firm performance. Second, this study points out that green dynamic capacities have positive effe...

  19. Optical absorption in irradiated natural beryl

    International Nuclear Information System (INIS)

    Three species of beryl irradiated with γ-rays of 60Co were studied by optical absorption. One became yellow and the other two Maxixe's blue. The effects of heat treatments were determined by the thermal isochronal decays of the optical absorption bands. Activation energies and frequency factor were obtained through the first order process kinetic model. Discussions lend us to assign for the UV band-edge the model of absorption by a hole center stabilized by a Fe2+ (substituting Al3+) ion in a neighbour oxygen. (Author)

  20. Comparison of box-air-mass-factors and radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) geometries calculated from different UV/visible radiative transfer models

    OpenAIRE

    Wagner, T.; J. P. Burrows; Deutschmann, T.; Dix, B.; Von Friedeburg, C.; Frieß, U.; F. Hendrick; K.-P. Heue; Irie, H.; H. Iwabuchi; Y. Kanaya; Keller, J.; Mclinden, C. A.; Oetjen, H.; Palazzi, E.

    2007-01-01

    International audience The results of a comparison exercise of radiative transfer models (RTM) of various international research groups for Multiple AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) viewing geometry are presented. Besides the assessment of the agreement between the different models, a second focus of the comparison was the systematic investigation of the sensitivity of the MAX-DOAS technique under various viewing geometries and aerosol conditions. In contrast to...

  1. Percutaneous absorption of nicotinic acid, phenol, benzoic acid and triclopyr butoxyethyl ester through rat and human skin in vitro: further validation of an in vitro model by comparison with in vivo data.

    Science.gov (United States)

    Hotchkiss, S A; Hewitt, P; Caldwell, J; Chen, W L; Rowe, R R

    1992-10-01

    The in vitro percutaneous absorption of three model compounds, nicotinic acid, phenol and benzoic acid, and the herbicide triclopyr butoxyethyl ester (triclopyr BEE) has been investigated in flow-through diffusion cells using skin from male Fischer 344 rats and humans. After the application of the four chemicals to the epidermal surface of unoccluded full-thickness rat skin, the absorption of each compound across the skin and into the receptor fluid at 72 hr reached 3.7 +/- 0.3, 5.7 +/- 0.6, 26.7 +/- 3.7 and 48.3 +/- 1.2% (mean +/- SD, n = 2-7) of the applied dose for triclopyr BEE, nicotinic acid, phenol and benzoic acid, respectively. After the application of the four chemicals to the epidermal surface of unoccluded full-thickness human skin, the absorption of each compound across the skin and into the receptor fluid at 72 hr was significantly (P triclopyr BEE, nicotinic acid, phenol and benzoic acid, respectively. Occlusion of the skin surface with teflon caps often significantly (P < 0.05) enhanced the percutaneous absorption of the model compounds, although this effect was not uniform, varying with the compound under study and the skin (rat or human) used. When rat skin was occluded with teflon caps, the extent of absorption at 72 hr reached 8.6 +/- 0.8, 36.2 +/- 1.7 and 51.8 +/- 3.3% (mean +/- SD, n = 3-4) for nicotinic acid, phenol and benzoic acid, respectively. Corresponding values for human skin occluded with teflon caps were 3.3 +/- 1.6, 47.1 +/- 0.5 and 65.5 +/- 7.1% (mean +/- SD, n = 3-4). The experiments on the absorption of each model compound through rat and human skin were repeated and there was generally good agreement between the results from the two sets of experiments. The in vitro data reported compare favourably with data obtained by other workers using both in vitro and in vivo methodologies. The in vitro: in vivo correlation supports the use of the flow-through diffusion cell system as a model for the prediction of percutaneous absorption

  2. Dust Sensitivity of Absorption-Line Indices

    CERN Document Server

    MacArthur, L A

    2004-01-01

    We investigate the effects of dust extinction on integrated absorption-line indices that are widely used to derive constraints on the ages and metallicities of composite stellar systems. Typically, absorption-line studies have been performed on globular clusters or elliptical galaxies, which are mostly dust-free systems. However, many recent studies of integrated stellar populations have focused on spiral galaxies which may contain significant amounts of dust. It is almost universally assumed that the effects of dust extinction on absorption-line measurements are entirely negligible given the narrow baseline of the spectral features, but no rigorous study has yet been performed to verify this conjecture. In this analysis, we explore the sensitivity of the standard set of Lick absorption-line indices, the higher-order Balmer line indices, the 4000 A break, the near-IR calcium triplet indices, and the Rose indices to dust absorption according to population synthesis models that incorporate a multi-component mod...

  3. Strategies for absorption screening in drug discovery and development

    OpenAIRE

    Bohets, H; Annaert, Pieter; Mannens, G.; van Beijsterveldt, L; Anciaux, K.; Verboven, P.; Meuldermans, W; Lavrijsen, K.

    2001-01-01

    This review gives an overview of the current approaches to evaluate drug absorption potential in the different phases of drug discovery and development. Methods discussed include in silico models, artificial membranes as absorption models, in vitro models such as the Ussing chamber and Caco-2 monolayers, in situ rat intestinal perfusion and in vivo absorption studies. In silico models such as iDEATM can help optimizing chemical synthesis since the fraction absorbed (Fa) can be predicted based...

  4. Optical absorption in LiF: Mg, Ti and its application to the Unified Interaction Model predictions of thermoluminescence dose response

    Energy Technology Data Exchange (ETDEWEB)

    Issa, N.; Oster, L.; Horowitz, Y.S. [Physics Department, Ben Gurion University of the Negev, Beersheva, 84105 (Israel)

    2000-07-01

    The optical absorption (OA) spectrum of LiF: Mg, Ti has been investigated by I{sub m} - T{sub stop} pulsed annealing in steps of 3-4 C over the temperature range from 100 C to 300 C. In agreement with previous investigations, the 5.45 eV OA band is identified as a likely candidate for the recombination stage competitor responsible for composite peak 5 supra linearity. An additional OA band at 5.7 eV is also identified as a possible recombination stage competitor. First order kinetic analysis yields an activation energy of 0.80 {+-} 0.13 eV for the 4.0 eV band usually associated with peak 5, an energy which is similar in value to the binding energy of the Mg-Li{sub vac} trimer believed to form the peak 5 trapping structure. Dose response measurements result in dose filling constants of {beta} {sub TC} = 0.9 {+-} 0.1 x 10{sup -3} Gy{sup -1} and {beta} {sub cc} = 3.8 {+-} 0.8 x 10 {sup -4} Gy{sup -1} for the 4.0 eV and 5.45 eV OA bands respectively. It is demonstrated quantitatively in the framework of the Unified Interaction Model (UNIM) that the experimentally measured peak 5 supra linearity can be theoretically predicted for all possible dose response characteristics of the competitor, i.e., early, late or no entry into saturation up to dose levels of 5000 Gy. Previous objections in the literature to the identification of the 5.45 eV OA band as the recombination stage competitor are therefore judged invalid. (Author)

  5. Aerosol absorption and radiative forcing

    Directory of Open Access Journals (Sweden)

    P. Stier

    2007-05-01

    Full Text Available We present a comprehensive examination of aerosol absorption with a focus on evaluating the sensitivity of the global distribution of aerosol absorption to key uncertainties in the process representation. For this purpose we extended the comprehensive aerosol-climate model ECHAM5-HAM by effective medium approximations for the calculation of aerosol effective refractive indices, updated black carbon refractive indices, new cloud radiative properties considering the effect of aerosol inclusions, as well as by modules for the calculation of long-wave aerosol radiative properties and instantaneous aerosol forcing. The evaluation of the simulated aerosol absorption optical depth with the AERONET sun-photometer network shows a good agreement in the large scale global patterns. On a regional basis it becomes evident that the update of the BC refractive indices to Bond and Bergstrom (2006 significantly improves the previous underestimation of the aerosol absorption optical depth. In the global annual-mean, absorption acts to reduce the short-wave anthropogenic aerosol top-of-atmosphere (TOA radiative forcing clear-sky from –0.79 to –0.53 W m−2 (33% and all-sky from –0.47 to –0.13 W m−2 (72%. Our results confirm that basic assumptions about the BC refractive index play a key role for aerosol absorption and radiative forcing. The effect of the usage of more accurate effective medium approximations is comparably small. We demonstrate that the diversity in the AeroCom land-surface albedo fields contributes to the uncertainty in the simulated anthropogenic aerosol radiative forcings: the usage of an upper versus lower bound of the AeroCom land albedos introduces a global annual-mean TOA forcing range of 0.19 W m−2 (36% clear-sky and of 0.12 W m−2 (92% all-sky. The consideration of black carbon inclusions on cloud radiative properties results in a small global annual-mean all-sky absorption of 0.05 W

  6. Absorptive capacity and smart companies

    Directory of Open Access Journals (Sweden)

    Patricia Moro González

    2014-12-01

    Full Text Available Purpose: The current competitive environment is substantially modifying the organizations’ learning processes due to a global increase of available information allowing this to be transformed into knowledge. This opportunity has been exploited since the nineties by the tools of “Business Analytics” and “Business Intelligence” but, nevertheless, being integrated in the study of new organizational capacities engaged in the process of creating intelligence inside organizations is still an outstanding task. The review of the concept of absorptive capacity and a detailed study from the perspective of this new reality will be the main objective of study of this paper.Design/methodology/approach: By comparing classical absorptive capacity and absorptive capacity from the point of view of information management tools in each one of the three stages of the organizational learning cycle, some gaps of the former are overcome/fulfilled. The academic/bibliographical references provided in this paper have been obtained from ISI web of knowledge, Scopus and Dialnet data bases, supporting the state of affairs on absorptive capacity and thereafter filtering by "Business Intelligence" and "Business Analytics". Specialized websites and Business Schools` Publications there have also been included, crowning the content on information management tools used that are currently used in the strategic consulting.Findings: Our contribution to the literature is the development of "smart absorptive capacity". This is a new capacity emerging from the reformulation of the classical concept of absorptive capacity wherein some aspects of its definition that might have been omitted are emphasized. The result of this new approach is the creation of a new Theoretical Model of Organizational Intelligence, which aims to explain, within the framework of the Resources and Capabilities Theory, the competitive advantage achieved by the so-called smart companies

  7. Absorptive capacity in organizational theories: learning, innovation, managerial cognition

    OpenAIRE

    O.A. Vasylieva

    2013-01-01

    The paper studies an important issue of absorptive capacity that enables the companies to strengthen their position in the competitive global market. The concept of absorptive capacity in open innovation paradigm is defined within the following organizational theories: learning, innovation and managerial cognition. The model which links together and clarifies in a detailed way the relationships between absorptive capacity and the components is proposed.

  8. Studies on N, P and K Absorption Characteristics of Rice Root System and Its Simulation Model%水稻根系氮磷钾吸收特性及其模拟模型研究

    Institute of Scientific and Technical Information of China (English)

    李娟; 章明清; 林琼; 颜明娟; 孔庆波

    2011-01-01

    The water culture and soil culture pot experiments were carried out for quantitative studies of N, P and K absorption characteristics during the whole growth period of rice. The results showed that there were 29 simulation models achieving significant level among 30 models of seven varieties of rice, which indicated the simulation model could be good fit for the nutrient absorption dynamics at different growth stages. According to simulation model,characteristic parameters, such as the nutrient uptaking constant of rice roots, the greatest rate of nutrient absorption,and the maximum nutrient uptake and their time of emergence, were obtained. The average value of root nutrient absorption constant was K> N> P; there was greater difference among potassium absorption constant of different varieties of rice while the difference among nitrogen or phosphorus was smaller. The calculation results of the greatest rate of nutrient absorption and the maximum nutrient uptake and their time of emergence showed that the absorption process of N and K was basically synchronous while that of phosphorus was later. Soil culture experiment showed that nutrient absorption constant, the greatest rate of nitrogen, phosphorus and potassium absorption and the maximum nutrient uptake were improved by balanced fertilization. The absorptive capacity of the nitrogen, phosphorus and potassium of the root was significantly increased.%为定量研究水稻一个生长周期的氮磷钾吸收特性,开展水培和土培盆栽试验.结果表明,7个水稻品种的30个模拟模型中,有29个模型达到统计显著水平,说明提出的模拟模型能很好地拟合水稻不同生育期的养分吸收动态.由模拟模型分析可得到水稻根系养分吸收常数、最大养分吸收速率和最大养分吸收量及其出现的时间等养分吸收特征参数.根系养分吸收常数平均值是K>N>P;不同品种间根系钾吸收常数有较大差异,氮和磷的差异则较小.养分

  9. Seven-effect absorption refrigeration

    Science.gov (United States)

    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.

  10. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model

    Science.gov (United States)

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested ...

  11. The Spectral Variability of the GHz-Peaked Spectrum Radio Source PKS 1718-649 and a Comparison of Absorption Models

    CERN Document Server

    Tingay, S J; Collier, J D; Rees, G; Callingham, J R; Stevens, J; Carretti, E; Wayth, R B; Wong, G F; Trott, C M; McKinley, B; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Corey, B E; Deshpande, A A; Emrich, D; Gaensler, B M; Goeke, R; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; Kaplan, D L; Kasper, J C; Kratzenberg, E; Lonsdale, C J; Lynch, M J; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Rogers, A E E; Roshi, A; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C L

    2014-01-01

    Using the new wideband capabilities of the Australia Telescope Compact Array (ATCA), we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over three epochs spanning approximately 21 months, reveal variability both above the spectral peak at ~3 GHz and below the peak. The combination of the low and high frequency variability cannot be easily explained using a single absorption mechanism, such as free-free absorption or synchrotron self-absorption. We find that the PKS 1718-649 spectrum and its variability are best explained by variations in the free-free optical depth on our line-of-sight to the radio source at low frequencies (below the spectral peak) and the adiabatic expansion of the radio source itself at high frequencies (above the spectral peak). The optical depth variations are found to be plausible when X-ray continuum absorption variability seen in samples of Active Galactic Nuclei is considered. We find that the ...

  12. Central cooling: absorptive chillers

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1977-08-01

    This technology evaluation covers commercially available single-effect, lithium-bromide absorption chillers ranging in nominal cooling capacities of 3 to 1,660 tons and double-effect lithium-bromide chillers from 385 to 1,060 tons. The nominal COP measured at operating conditions of 12 psig input steam for the single-effect machine, 85/sup 0/ entering condenser water, and 44/sup 0/F exiting chilled-water, ranges from 0.6 to 0.65. The nominal COP for the double-effect machine varies from 1.0 to 1.15 with 144 psig entering steam. Data are provided to estimate absorption-chiller performance at off-nominal operating conditions. The part-load performance curves along with cost estimating functions help the system design engineer select absorption equipment for a particular application based on life-cycle costs. Several suggestions are offered which may be useful for interfacing an absorption chiller with the remaining Integrated Community Energy System. The ammonia-water absorption chillers are not considered to be readily available technology for ICES application; therefore, performance and cost data on them are not included in this evaluation.

  13. QED-driven laser absorption

    CERN Document Server

    Levy, M C; Ratan, N; Sadler, J; Ridgers, C P; Kasim, M; Ceurvorst, L; Holloway, J; Baring, M G; Bell, A R; Glenzer, S H; Gregori, G; Ilderton, A; Marklund, M; Tabak, M; Wilks, S C; Norreys, P A

    2016-01-01

    Absorption covers the physical processes which convert intense photon flux into energetic particles when a high-power laser illuminates optically-thick matter. It underpins important petawatt-scale applications today, e.g., medical-quality proton beam production. However, development of ultra-high-field applications has been hindered since no study so far has described absorption throughout the entire transition from the classical to the quantum electrodynamical (QED) regime of plasma physics. Here we present a model of absorption that holds over an unprecedented six orders-of-magnitude in optical intensity and lays the groundwork for QED applications of laser-driven particle beams. We demonstrate 58% efficient \\gamma-ray production at $1.8\\times 10^{25}~\\mathrm{W~ cm^{-2}}$ and the creation of an anti-matter source achieving $4\\times 10^{24}\\ \\mathrm{positrons}\\ \\mathrm{cm^{-3}}$, $10^{6}~\\times$ denser than of any known photonic scheme. These results will find applications in scaled laboratory probes of bla...

  14. Percutaneous absorption from soil.

    Science.gov (United States)

    Andersen, Rosa Marie; Coman, Garrett; Blickenstaff, Nicholas R; Maibach, Howard I

    2014-01-01

    Abstract Some natural sites, as a result of contaminants emitted into the air and subsequently deposited in soil or accidental industrial release, have high levels of organic and non-organic chemicals in soil. In occupational and recreation settings, these could be potential sources of percutaneous exposure to humans. When investigating percutaneous absorption from soil - in vitro or vivo - soil load, particle size, layering, soil "age" time, along with the methods of performing the experiment and analyzing the results must be taken into consideration. Skin absorption from soil is generally reduced compared with uptake from water/acetone. However, the absorption of some compounds, e.g., pentachlorophenol, chlorodane and PCB 1254, are similar. Lipophilic compounds like dichlorodiphenyltrichloroethane, benzo[A]pyrene, and metals have the tendency to form reservoirs in skin. Thus, one should take caution in interpreting results directly from in vitro studies for risk assessment; in vivo validations are often required for the most relevant risk assessment. PMID:25205703

  15. XUV Absorption by Solid Density Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Intercomparing CO2 amounts from dispersion modeling, 1.6 μm differential absorption lidar and open path FTIR at a natural CO2 release at Caldara di Manziana, Italy

    Directory of Open Access Journals (Sweden)

    M. Queißer

    2015-04-01

    Full Text Available We intercompare results of three independent approaches to quantify a vented CO2 release at a strongly non-uniform CO2 Earth degassing at Caldara di Manziana, central Italy. An integrated path differential absorption lidar prototype and a commercial open path FTIR system were measuring column averaged CO2 concentrations in parallel at two different paths. An Eulerian gas dispersion model simulated 3-D CO2 concentration maps in the same area, using in situ CO2 flux input data acquired at 152 different points. Local processes the model does not account for, such as small-scale and short-lived wind eddies, govern CO2 concentrations in the instrument measurement paths. The model, on the other hand, also considers atmospheric effects that are out of the field of view of the instruments. Despite this we find satisfactory agreement between modeled and measured CO2 concentrations under certain meteorological conditions. Under these conditions the results suggest that an Eulerian dispersion model and optical remote sensing can be used as an integrated, complementary monitoring approach for CO2 hazard or leakage assessment. Furthermore, the modeling may assist in evaluating CO2 sensing surveys in the future. CO2 column amounts from differential absorption lidar are in line with those from FTIR for both paths with a mean residual of the time series of 44 and 34 ppm, respectively. This experiment is a fundamental step forward in the deployment of the differential absorption lidar prototype as a highly portable active remote sensing instrument probing vented CO2 emissions, including volcanoes.

  17. Effect of phytate reduction of sorghum, through genetic modification, on iron and zinc availability as assessed by an in vitro dialysability bioaccessibility assay, Caco-2 cell uptake assay, and suckling rat pup absorption model.

    Science.gov (United States)

    Kruger, Johanita; Taylor, John R N; Du, Xiaogu; De Moura, Fabiana F; Lönnerdal, Bo; Oelofse, André

    2013-11-15

    Improved iron and zinc availability from sorghum, a commonly consumed staple, will benefit many malnourished communities in rural Africa burdened with high prevalence of iron and zinc deficiency. This research compared the effect of genetic phytate reduction in sorghum on iron and zinc bioaccessibility and uptake measured by in vitro dialysability and Caco-2 cell uptake assays to that of iron and zinc absorption measured by a suckling rat pup model. The phytate reduction (80-86%) in these sorghums significantly increased zinc availability. The Caco-2 cell method, but not the dialysability assay, proved useful in estimating zinc absorption. The measured increase in iron availability differed between the methods, possibly due to the effect of varying mineral (Ca, Fe, Zn, P) contents of the sorghums. This effect was most prominent in the iron uptake results. More research is needed to determine the effect of naturally occurring variations in mineral contents of sorghum on the iron uptake by Caco-2 cells.

  18. Observation of different phytoplankton groups and biomass using Differential Optical Absorption Spectroscopy on SCIAMACHY data and comparisons to in-situ, NASA biogeochemical Model and MERIS

    OpenAIRE

    Bracher, Astrid; Taylor, Bettina; M. Vountas; Dinter, Tilman; J. P. Burrows; R. Röttgers; Peeken, Ilka

    2008-01-01

    In order to understand the marine phytoplanktons role in the global marine ecosystem and biogeochemical cycles it is necessary to derive global information on the distribution of major functional phytoplankton types (PFT) in the world oceans. In our study we use instead of the common ocean color sensors such as CZCS, SeaWiFS, MODIS, MERIS, with rather low spectral resolution, the Differential Optical Absorption Spectroscopy (DOAS) to study the retrieval of phytoplankton distribution and absor...

  19. Study of O, N, and F absorption in calcium-thermal alloy Zr 1% Nb (KTTs - 110) during fuel element model preparation

    International Nuclear Information System (INIS)

    The nuclear-physical methods of analysis (NPMA) are used to research an absorption of impurities (oxygen, nitrogen) from the technological environments during operations of welding of hardware products from zirconium alloys doped 1%Nb, and fluorine after a technological etching in solutions containing of fluorine. The techniques and engineering of carrying out of NPMA are described, the impurity concentrations of oxygen, nitrogen, fluorine and their allocation in surface layers of welded seams are defined before and after chemical treatments

  20. 大鼠在体肠灌流模型对豆腐果苷在体吸收的初步研究%Absorption behavior of helicid using rat in situ recirculating perfusion model

    Institute of Scientific and Technical Information of China (English)

    贾元威; 谢海棠; 沈杰; 王幼林; 梁大虎; 罗强

    2011-01-01

    Aim To study helicid absorption behavior by using rat in situ recirculating perfusion model. Methods This study was built on HPLC quantitative method of helicid in Krebs-Ringer solution , and detection of phenolsulfonphthalein concentration in Krebs-Ringer solution through ultraviolet spectrophotometer model 752, using rat in situ recirculating perfusion model to do preliminary study on the absorption behavior of helicid. Results The absorption of helicid in rat ' s superior part of duodenum to inferior part of ileum in 2 hours was quick and the trend of absorption reached flat within 15 ~ 20 min. Conclusion The method successfully builds rat in situ recirculating perfusion model and makes a preliminary study on the absorption behavior of helicid, thus lays the foundation of the following research of helicid in vivo disposition situation.%目的 应用大鼠在体肠灌流模型对豆腐果苷吸收机制进行研究.方法 该实验在建立豆腐果苷在Krebs-Ringer缓冲液中的检测方法,及应用752紫外分光光度计测定Krebs-Ringer缓冲液中酚红溶液浓度的基础上,应用大鼠肠灌流模型研究豆腐果苷的吸收情况.结果 通过该模型对豆腐果苷在大鼠十二指肠上部至回肠下部肠段中2 h内吸收情况的研究发现,豆腐果苷吸收迅速,15~20 min吸收即可达到平台.结论 该实验建立了大鼠小肠灌流模型,并且将该模型用于豆腐果苷吸收情况的初步研究,为揭示豆腐果苷体内处置情况奠定了基础.

  1. Chemical Absorption Materials

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    2011-01-01

    Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...

  2. Absorption driven focus shift

    Science.gov (United States)

    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.

  3. ZINC ABSORPTION BY INFANTS

    Science.gov (United States)

    Zinc is a vital mineral in human nutrition, and rare cases of overt zinc deficiency are well described in term and preterm infants. A variety of methods have been developed to assess zinc absorption, retention, and balance in humans, either using mass (metabolic) balance or stable isotope-based METH...

  4. Radiation Absorption Mechanism in Nonvolatile MNOS Structure

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The γ-ray radiation will speed up the discharge of the stored charge in nonvolatile MNOS structure. The radiation absorption mechanism to enhance the discharge is discussed. A direct radiation emission model from the interface traps distributing both in energy level and in space is given. The theoretical results based on this model are in good agreement with experimental measurement.

  5. Investigation of two-photon absorption induced excited state absorption in a fluorenyl-based chromophore.

    Science.gov (United States)

    Li, Changwei; Yang, Kun; Feng, Yan; Su, Xinyan; Yang, Junyi; Jin, Xiao; Shui, Min; Wang, Yuxiao; Zhang, Xueru; Song, Yinglin; Xu, Hongyao

    2009-12-01

    Two-photon absorption induced excited state absorption in the solution of a new fluorenyl-based chromophore is investigated by a time-resolved pump-probe technique using femtosecond pulses. With the help of an additional femtosecond open-aperture Z-scan technique, numerical simulations based on a three-energy level model are used to interpret the experimental results, and we determine the nonlinear optical parameters of this new chromophore uniquely. Large two-photon absorption cross section and excited state absorption cross section for singlet excited state are obtained, indicating a good candidate for optical limiting devices. Moreover, the influence of two-beam coupling induced energy transfer in neat N,N'-dimethylformamide solvent is also considered, although this effect is strongly restrained by the instantaneous two-photon absorption. PMID:19894682

  6. Percutaneous absorption in diseased skin: an overview.

    Science.gov (United States)

    Chiang, Audris; Tudela, Emilie; Maibach, Howard I

    2012-08-01

    The stratum corneum's (SC) functions include protection from external hazardous environments, prevention of water loss and regulation of body temperature. While intact skin absorption studies are abundant, studies on compromised skin permeability are less common, although products are often used to treat affected skin. We reviewed literature on percutaneous absorption through abnormal skin models. Tape stripping is used to disrupt water barrier function. Studies demonstrated that physicochemical properties influence the stripping effect: water-soluble drugs are more affected. Abrasion did not affect absorption as much. Freezing is commonly used to preserve skin. It does not seem to modify water absorption, but still increases the penetration of compounds. Comparatively, heating the skin consistently increased percutaneous absorption. Removing SC lipids may increase percutaneous absorption of drugs. Many organic solvents are employed to delipidize. Delipidization with chloroform-methanol increased hydrophilic compound permeability, but not lipophilic. Acetone pre-treatment enhanced hydrophilic compound penetration. More data is needed to determine influence on highly lipophilic compound penetration. Sodium lauryl sulfate (SLS) induces irritant dermatitis and is frequently used as a model. Studies revealed that SLS increases hydrophilic compound absorption, but not lipophilic. However, skin irritation with other chemicals increases lipophilic penetration as much as hydrophilic. Animal studies show that UV exposure increases percutaneous absorption whereas human studies do not. Human studies show increased penetration in psoriatic and atopic dermatitis skin. The data summarized here begin to characterize flux alteration associated with damaged skin. Understanding the degree of alteration requires interpretation of involved conditions and the enlarging of our database to a more complete physicochemical spectrum. PMID:22912973

  7. Aerosol scattering and absorption during the EUCAARI-LONGREX flights of the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146: can measurements and models agree?

    Science.gov (United States)

    Highwood, E. J.; Northway, M. J.; McMeeking, G. R.; Morgan, W. T.; Liu, D.; Osborne, S.; Bower, K.; Coe, H.; Ryder, C.; Williams, P.

    2012-08-01

    Scattering and absorption by aerosol in anthropogenically perturbed air masses over Europe has been measured using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM) on 14 flights during the EUCAARI-LONGREX campaign in May 2008. The geographical and temporal variations of the derived shortwave optical properties of aerosol are presented. Values of single scattering albedo of dry aerosol at 550 nm varied considerably from 0.86 to near unity, with a campaign average of 0.93 ± 0.03. Dry aerosol optical depths ranged from 0.030 ± 0.009 to 0.24 ± 0.07. An optical properties closure study comparing calculations from composition data and Mie scattering code with the measured properties is presented. Agreement to within measurement uncertainties of 30% can be achieved for both scattering and absorption, but the latter is shown to be sensitive to the refractive indices chosen for organic aerosols, and to a lesser extent black carbon, as well as being highly dependent on the accuracy of the absorption measurements. Agreement with the measured absorption can be achieved either if organic carbon is assumed to be weakly absorbing, or if the organic aerosol is purely scattering and the absorption measurement is an overestimate due to the presence of large amounts of organic carbon. Refractive indices could not be inferred conclusively due to this uncertainty, despite the enhancement in methodology compared to previous studies that derived from the use of the black carbon measurements. Hygroscopic growth curves derived from the wet nephelometer indicate moderate water uptake by the aerosol with a campaign mean f(RH) value (ratio in scattering) of 1.5 (range from 1.23 to 1.63) at 80% relative humidity. This value is qualitatively consistent with the major chemical components of the aerosol measured by the aerosol mass spectrometer, which are primarily mixed organics and

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

    Energy Technology Data Exchange (ETDEWEB)

    Jefferson, Anne [National Oceanic and Atmospheric Administration (NOAA), Washington, DC (United States)

    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.

  9. Spectral Absorption Properties of Atmospheric Aerosols

    Science.gov (United States)

    Bergstrom, R. W.; Pilewskie, P.; Russell, P. B.; Redemann, J.; Bond, T. C.; Quinn, P. K.; Sierau, B.

    2007-01-01

    We have determined the solar spectral absorption optical depth of atmospheric aerosols for specific case studies during several field programs (three cases have been reported previously; two are new results). We combined airborne measurements of the solar net radiant flux density and the aerosol optical depth with a detailed radiative transfer model for all but one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom Exponent or AAE). We compare our results with other recent spectral absorption measurements and attempt to briefly summarize the state of knowledge of aerosol absorption spectra in the atmosphere. We discuss the limitations in using the AAE for calculating the solar absorption. We also discuss the resulting spectral single scattering albedo for these cases.

  10. Absorptive Capacity and Diversity

    DEFF Research Database (Denmark)

    Kristinsson, Kári

    that contribute to the neo-Schumpeterian economics literature and hopefully inspires further research into this area. The main findings of the dissertation can be divided into four distinct parts. First, diversity of individuals within firms is associated with firm innovative performance. This is in line......One of the most influential contributions to neo-Schumpeterian economics is Cohen and Levinthal‘s papers on absorptive capacity. Since their publication in the late 1980s and early 1990s the concept absorptive capacity has had substantial impact on research in economics and management, including...... international business, organizational economics, strategic management, technology management and last but not least neo-Schumpeterian economics. The goal of this dissertation is to examine what many consider as neglected arguments from the work by Cohen and Levinthal and thereby illuminate an otherwise...

  11. Acoustic absorption by sunspots

    Science.gov (United States)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  12. Acoustic absorption by sunspots

    Energy Technology Data Exchange (ETDEWEB)

    Braun, D.C.; Labonte, B.J.; Duvall, T.L. Jr.

    1987-08-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity. 10 references.

  13. 细胞共培养模型在口服药物吸收研究中的应用%Application of cell co-culture models in absorption of oral drug

    Institute of Scientific and Technical Information of China (English)

    黎迎; 朱春燕

    2015-01-01

    细胞共培养体系能很好地模拟人体小肠生理环境,准确预测药物在肠道内的转运和代谢情况,增强体外细胞模型与整体动物实验研究之间的相关性,近年来在评价口服药物吸收方面发挥着越发重要的作用,已成为新药研发过程中评价药物口服吸收的热点。综述体外模拟肠道环境的细胞共培养模型,并对其应用于口服药物研发的体外评价吸收做出展望。%Cell co-culture system can better simulate the inner environment of human body ,predict drug transport and metabolism in intestinal environment and increase the relation between in vitro cell model and integral animal test .In recent years ,co-culture cell model plays an increasingly important role in evaluating the absorption of oral drugs ,which becomes the highlight in the evaluation of drug oral absorption during new drug discovery .This essay summarized co-culture cell model which simulates intestinal environment and their application ,and looked into the future of their application in evaluating oral drug intestinal absorption during oral drug discovery .

  14. 细胞共培养模型在口服药物吸收研究中的应用%Application of cell co-culture models in absorption of oral drug

    Institute of Scientific and Technical Information of China (English)

    黎迎; 朱春燕

    2015-01-01

    Cell co-culture system can better simulate the inner environment of human body ,predict drug transport and metabolism in intestinal environment and increase the relation between in vitro cell model and integral animal test .In recent years ,co-culture cell model plays an increasingly important role in evaluating the absorption of oral drugs ,which becomes the highlight in the evaluation of drug oral absorption during new drug discovery .This essay summarized co-culture cell model which simulates intestinal environment and their application ,and looked into the future of their application in evaluating oral drug intestinal absorption during oral drug discovery .%细胞共培养体系能很好地模拟人体小肠生理环境,准确预测药物在肠道内的转运和代谢情况,增强体外细胞模型与整体动物实验研究之间的相关性,近年来在评价口服药物吸收方面发挥着越发重要的作用,已成为新药研发过程中评价药物口服吸收的热点。综述体外模拟肠道环境的细胞共培养模型,并对其应用于口服药物研发的体外评价吸收做出展望。

  15. Enhanced Water Vapor Absorption within Tropospheric Clouds: A Partial Explanation for Anomalous Absorption

    Science.gov (United States)

    Crisp, David; Zuffada, Cinzia

    1996-01-01

    Comparisons between solar flux measurements and predictions obtained from theoretical radiative transfer models indicate that most of these models underestimate the globally averaged solar energy absorbed by cloudy atmospheres by up to 25Wm&sup-2;.The origin of this anomalous absorption has not yet been established, but it has been attributed to a variety of sources including oversimplified or missing physical processes in the existing models, uncertainties in the input data, and even measurement errors. We used a sophisticated atmospheric radiative transfer model to provide improved constraints on the physical processes that contribute to the absorption of solar radiation by Earth's atmosphere. The results are described herein.

  16. Sensitivity of the CCM climate to enhanced cloud absorption

    Energy Technology Data Exchange (ETDEWEB)

    Kiehl, J. [National Center for Atmospheric Research (NCAR), Boulder, CO (United States)

    1995-09-01

    Recent indications suggest that clouds may be absorbing more solar radiation than was previously thought. This research investigates some of the evidence for this hypothesis; potential physical mechanisms are briefly discussed as well. The climatic implications of the enhanced absorption are investigated using the NCAR Community Climate Model (CCM). It is found that the model`s heat budget in the tropical warm pool agrees more closely with observations when enhanced absorption is included. On the whole, the addition of enhanced absorption improves the model`s performance in the tropics and degrades it in the extra-tropics. 3 figs.

  17. 脂质制剂体外动态肠吸收模型的建立及评价%Establishment and evaluation of a dynamic in vitro intestinal absorption model of lipid formulations

    Institute of Scientific and Technical Information of China (English)

    刘颖; 易涛; 宦娣; 肖璐; 何吉奎

    2011-01-01

    A new dynamic in vitro intestinal absorption model for screening and evaluating lipid formulations was established by means of the characteristics of the intestinal digestion and absorption of the lipid formulations. This model was composed of two systems, including intestinal digestion and the intestinal tissue culture, which drew the evaluation method of intestinal absorption into the in vitro lipolysis model. The influence of several important model parameters such as Ca2+, D-glucose, K+ on the two systems of this model has been investigated. The results showed that increasing of Ca2+ concentration could be significantly conductive to intestinal digestion. The increasing of .D-glucose concentration could stepped significantly down the decay of the intestinal activity. K+ was able to maintain intestinal activity, but the influence of different concentration levels on the decay of the intestinal activity was of no significant difference. Thus the model parameters were set up as follows: Ca2+ for 10 mmol-L-1, D-glucose for 15 mmol-L-1 and K+ for 5.5 mmol-L-1. Type I lipid formulation was evaluated with this model, and there was a significant correlation between the absorption curve in vitro and absorption curve in vivo of rats (r = 0.995 6, P < 0.01). These results demonstrated that this model can be an attractive and great potential method for the screening, evaluating and predicting of the lipid formulations.%根据脂质制剂肠消化吸收的特性,本文在体外脂解模型基础上,引入肠吸收评价方法,建立了一种用于筛选评价脂质制剂的新型体外动态肠吸收模型,包括肠消化和肠组织培养两大体系.探究模型重要参数(Ca2+、葡萄糖、K+)的影响,发现Ca2+浓度的增加能显著增强脂质制剂的肠消化;葡萄糖浓度的递增能显著减慢肠组织活性衰减;K+虽能维持肠组织的活性,但其浓度变化对肠组织活性衰减并无显著性影响;最终选择Ca2+l0 mmol·L-1、葡萄糖15 mmol

  18. Watching adsorption and electron beam induced decomposition on the model system Mo(CO){sub 6}/Cu(1 1 1) by X-ray absorption and photoemission spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Paufert, Pierre, E-mail: pierre.paufert@u-bourgogne.fr [ICB, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon cedex (France); Fonda, Emiliano [Synchrotron SOLEIL, BP48, St Aubin, 91192 Gif sur Yvette cedex (France); Li, Zheshen [ISA, University of Aarhus, Ny Munkegade, DK-8000 Aarhus C (Denmark); Domenichini, Bruno, E-mail: bruno.domenichini@u-bourgogne.fr [ICB, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon cedex (France); Bourgeois, Sylvie [ICB, UMR 6303 CNRS-Université de Bourgogne, BP 47870, 21078 Dijon cedex (France)

    2013-11-01

    An in-depth study of the first steps of electron beam assisted growth of Mo from molybdenum hexacarbonyl on Cu(1 1 1) has been carried out exploiting the complementarity of X-ray photoemission and X-ray absorption spectroscopies. Frank van der Merwe (2D) growth mode has been observed for the completion of the two first monolayers of adsorbed molecules through a simple physisorption process. Irradiation of the Mo(CO){sub 6} deposit by 1 keV electron beam induces a modification of molybdenum coordination, the average number of C-neighbors decreasing from 6 to 3. Decomposed molecules remain on the surface after annealing at 520 K and organize themselves, the molybdenum atoms moving in Cu(1 1 1) surface fcc hollow sites. After annealing at 670 K, metallic molybdenum growth begins, if the total amount of adsorbed Mo atoms exceeds 1.2 monolayers.

  19. Watching adsorption and electron beam induced decomposition on the model system Mo(CO)6/Cu(1 1 1) by X-ray absorption and photoemission spectroscopies

    Science.gov (United States)

    Paufert, Pierre; Fonda, Emiliano; Li, Zheshen; Domenichini, Bruno; Bourgeois, Sylvie

    2013-11-01

    An in-depth study of the first steps of electron beam assisted growth of Mo from molybdenum hexacarbonyl on Cu(1 1 1) has been carried out exploiting the complementarity of X-ray photoemission and X-ray absorption spectroscopies. Frank van der Merwe (2D) growth mode has been observed for the completion of the two first monolayers of adsorbed molecules through a simple physisorption process. Irradiation of the Mo(CO)6 deposit by 1 keV electron beam induces a modification of molybdenum coordination, the average number of C-neighbors decreasing from 6 to 3. Decomposed molecules remain on the surface after annealing at 520 K and organize themselves, the molybdenum atoms moving in Cu(1 1 1) surface fcc hollow sites. After annealing at 670 K, metallic molybdenum growth begins, if the total amount of adsorbed Mo atoms exceeds 1.2 monolayers.

  20. A Theoretical Modeling of Light Absorption and Scattering Properties about Microcystis Aeruginosa%铜绿微囊藻吸收和散射特性理论模拟

    Institute of Scientific and Technical Information of China (English)

    戴红亮; 吕恒; 李云梅; 查桂红; 李晓俊; 王瑜

    2013-01-01

    According to ADA theory and Kramers-Kronig relationship,the real and imaginary parts of complex refractive index were estimated by the datasets of microcystis aeruginosa algal absorption and particle size distribution.Then,the optical properties of microcystis aeruginosa were calculated based on the Mie theory.The relative deviations between modeled and measured scattering efficiency factors are 10.08%,and 4.8% between absorption efficiency factors.The agreements between simulation result and actual measurement show that homogenous spherical model can be used to reproduce the absorption and scattering property of microcystis aeruginosa.%基于奇异衍射近似理论和Kramers-Kronig关系,通过实测铜绿微囊藻的吸收光谱数据和粒径分布估算出铜绿微囊藻折射率的实部和虚部,结合Mie散射理论,计算出铜绿微囊藻的吸收效率光谱、散射效率光谱.对比模拟结果与实验结果发现:该模型估算得到的散射光谱与实验的散射光谱之间误差为10.08%,吸收效率的误差为4.8%.从模拟结果与实测结果来看,均匀球形模型能够较好的重现铜绿微囊藻的吸收和散射特征.

  1. Shell structure of pancakes and the absorption spectra of quasars

    International Nuclear Information System (INIS)

    The formation of the absorption lines of atomic hydrogen in the spectra of distant quasars is considered. A model is constructed of the formation of shells of a pancake formed in the adiabatic picture of the generation of the large-scale structure of the universe. It is shown that the absorption lines can form doublets and the equivalent widths of the corresponding lines are calculated. The physical conditions corresponding to the observed heavy-element absorption spectra are discussed

  2. Absorptive capacity in organizational theories: learning, innovation, managerial cognition

    Directory of Open Access Journals (Sweden)

    O.A. Vasylieva

    2013-12-01

    Full Text Available The paper studies an important issue of absorptive capacity that enables the companies to strengthen their position in the competitive global market. The concept of absorptive capacity in open innovation paradigm is defined within the following organizational theories: learning, innovation and managerial cognition. The model which links together and clarifies in a detailed way the relationships between absorptive capacity and the components is proposed.

  3. Absorption heat pumps

    Science.gov (United States)

    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.

  4. Scattering with absorptive interaction

    Science.gov (United States)

    Cassing, W.; Stingl, M.; Weiguny, A.

    1982-07-01

    The S matrix for a wide class of complex and nonlocal potentials is studied, with special attention given to the motion of singularities in the complex k plane as a function of the imaginary coupling strength. Modifications of Levinson's theorem are obtained and discussed. Analytic approximations to the S matrix in the vicinity of narrow resonances are exhibited and compared to numerical results of resonating-group calculations. The problem of defining resonances in the case of complex interactions is discussed, making contact with the usual analysis of scattering in terms of Argand diagrams. NUCLEAR REACTIONS Scattering theory, S matrix for absorptive potentials.

  5. Geospatial Absorption and Regional Effects

    Directory of Open Access Journals (Sweden)

    IOAN MAC

    2009-01-01

    Full Text Available The geospatial absorptions are characterized by a specific complexity both in content and in their phenomenological and spatial manifestation fields. Such processes are differentiated according to their specificity to pre-absorption, absorption or post-absorption. The mechanisms that contribute to absorption are extremely numerous: aggregation, extension, diffusion, substitution, resistivity (resilience, stratification, borrowings, etc. Between these mechanisms frequent relations are established determining an amplification of the process and of its regional effects. The installation of the geographic osmosis phenomenon in a given territory (a place for example leads to a homogenization of the geospatial state and to the installation of the regional homogeneity.

  6. Impact of transporters in oral absorption

    DEFF Research Database (Denmark)

    Gram, Luise Kvisgaard; Rist, Gerda Marie; Steffansen, Bente

    2009-01-01

    permeation of A275 was concentration dependent and affected by inhibitors or competitive organic anions. Interactions related to transporters in intestinal permeation was clearly demonstrated in the Caco-2 cell model but was not directly evident for in vivo rat absorption. However, an observed biphasic...

  7. Electromagnetically-enhanced saturable absorption

    CERN Document Server

    Su, Chun-Hsu; Beausoleil, Raymond G; Hollenberg, Lloyd C L; Munro, William J; Nemoto, Kae; Spiller, Timothy P

    2009-01-01

    Electromagnetically-induced transparency (EIT) exploits quantum coherence to burn subnatural linewidth holes within a spectral line. It is typically discussed in the context of a pump-probe configuration in a three-level L system, where the pump is often significantly stronger than the probe. Here we remove such restrictions on the relative intensities of pump and probe fields, and furthermore show that the absorptive properties associated with EIT can be of benefit in absorptive nonlinear processes, especially saturable absorption. We show that in a three-level medium near the EIT condition, we can generate saturable absorption qualitatively similar to two-state saturable absorption. The difference is that we can explore saturable absorption against the ground-state dephasing, rather than spontaneous emission. This has the advantages of significantly more controllability, and more importantly, different intensity scalings in the absorption. Such effects could prove useful for signal regeneration at very low ...

  8. The HI absorption 'Zoo'

    CERN Document Server

    Gereb, K; Morganti, R; Oosterloo, T A

    2014-01-01

    We present an analysis of the HI absorption in a sample of 101 flux-selected radio AGN (S_1.4 GHz > 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). HI absorption is detected in 32 galaxies, showing a broad variety of widths, shapes and kinematical properties. We characterize the HI spectra of the individual detections using the busy function (Westmeier et al. 2014). With the goal of identifying different morphological structures of HI, we study the kinematical and radio source properties of the detections as function of their width. Narrow lines (FWHM = 500 km/s). These detections are good candidates for being HI outflows. The detection rate of HI outflows is 5 percent in the total radio AGN sample. This fraction represents a lower limit, however it could suggests that, if outflows are a characteristic phenomenon of all radio sources, they would have a short depletion timescale compared to the lifetime of the AGN. Blueshifted and broad/asymmetric lines are more often present among young...

  9. Modelos in vitro para determinação da absorção de fármacos e previsão da relação dissolução/absorção In vitro models for the determination of drug absorption and a prediction of dissolution/absorption relationships

    Directory of Open Access Journals (Sweden)

    Jacqueline de Souza

    2007-12-01

    and absorption of drugs using in vitro models. There are several methods for determining in vitro intestinal permeability. These include diffusion studies with intestinal segments from various species or with cultured cell monolayer. Some of the most commonly used cell models are Caco-2, TC-7, 2/4/A1 and MDCK. Caco-2 cells have been the most extensively characterized and useful cell models. The Caco-2 cell, a human colon adenocarcinoma, undergoes spontaneous enterocytic differentiation in culture. A dissolution Caco-2 system has been developed to predict dissolution/absorption relationships of oral solid dosage forms of drugs prior to human studies. The in vitro permeability models represent an important tool for drug discovery within the pharmaceutical industry. However, similar models are likely to generate false negative results with actively transported drugs, and the use of a sophisticated mathematical model could be required.

  10. EMPLOYMENT ABSORPTION IN MANUFACTURING INDUSTRY: YOGYAKARTA CASE

    Directory of Open Access Journals (Sweden)

    Aurora Indra Putri

    2011-09-01

    Full Text Available Unemployment has been a main problem in economic development, especially in developing countries. Unemployment stems from the inability of the economy to absorb the growing labor force. This paper investigates factors influencing absorbtion of labor in Yogyakarta manufacturing industries. Variables hypothesized to affect the absorbtion are wage, labor productivity, non-wage spending, and output of production. It collects data from Indonesia Centre Bureau of Statistics, and uses panel data regression, namely common effect approach, to estimate the model. Employing Eviews software package, it finds that wage, labor productivity, and output production significantly influence labor absorption. However, non-wage spending does not significantly influence the absorption.Keywords: Labor absorption, wage, labor productivity, non-wage spendingJEL classification numbers: J01, J23, J24

  11. Molecular absorption in Cen A on VLBI scales

    CERN Document Server

    Van Langevelde, H J; Beasley, A

    2004-01-01

    Centaurus A, the nearest AGN shows molecular absorption in the millimeter and radio regime. By observing the absorption with VLBI, we try to constrain the distribution of the gas, in particular whether it resides in the circumnuclear region. Analysis of VLBA observations in four OH and two H2CO transitions is presented here, as well as molecular excitation models parameterized with distance from the AGN. We conclude that the gas is most likely associated with the tilted molecular ring structure observed before in molecular emission and IR continuum. The formaldehyde absorption shows small scale absorption which requires a different distribution than the hydroxyl.

  12. Is oral absorption of vigabatrin carrier-mediated?

    DEFF Research Database (Denmark)

    Nøhr, M. K.; Juul, R. V.; Thale, Z. I.;

    2015-01-01

    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......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 (0.3-300 mg/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...

  13. X-ray Absorption Spectroscopy and Coherent X-ray Diffraction Imaging for Time-Resolved Investigation of the Biological Complexes: Computer Modelling towards the XFEL Experiment

    Science.gov (United States)

    Bugaev, A. L.; Guda, A. A.; Yefanov, O. M.; Lorenz, U.; Soldatov, A. V.; Vartanyants, I. A.

    2016-05-01

    The development of the next generation synchrotron radiation sources - free electron lasers - is approaching to become an effective tool for the time-resolved experiments aimed to solve actual problems in various fields such as chemistry’ biology’ medicine’ etc. In order to demonstrate’ how these experiments may be performed for the real systems to obtain information at the atomic and macromolecular levels’ we have performed a molecular dynamics computer simulation combined with quantum chemistry calculations for the human phosphoglycerate kinase enzyme with Mg containing substrate. The simulated structures were used to calculate coherent X-ray diffraction patterns’ reflecting the conformational state of the enzyme, and Mg K-edge X-ray absorption spectra, which depend on the local structure of the substrate. These two techniques give complementary information making such an approach highly effective for time-resolved investigation of various biological complexes, such as metalloproteins or enzymes with metal-containing substrate, to obtain information about both metal-containing active site or substrate and the atomic structure of each conformation.

  14. Statistical method for predicting protein absorption peaks in terahertz region

    International Nuclear Information System (INIS)

    Terahertz vibrational spectroscopy has recently been demonstrated as a novel noninvasive technique for the characterization of biological molecules. But the interpretation of the experimentally measured terahertz absorption bands requires robust computational method. In this paper, we present a statistical method for predicting the absorption peak positions of a macromolecule in the terahertz region. The essence of this method is to calculate the absorption spectra of a biological molecule based on multiple short scale molecular dynamics trajectories instead of using a long time scale trajectory. The method was employed to calculate the absorption peak positions of the protein, thioredoxin from Escherichia coli (E.coli), in the range of 10-25 cm-1 to verify the reliability of this statistical method. The predicted absorption peak positions of thioredoxin show good correlation with measured results demonstrating that the proposed method is effective in terahertz absorption spectra modeling. Such approach can be applied to predict characteristic spectral features of biomolecules in the terahertz region. (authors)

  15. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    XIANG FuYuan; LIANG ShunLin; LI AiGen

    2009-01-01

    The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear. This article reviews the history of the detec-tions of DIBs in the Milky Way and external galaxies, the major observational characteristics of DIBs, the correlations or anti-correlations among DIBs or between DIBs and other interstellar features (e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise), and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  16. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The diffuse interstellar bands(DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s,the exact nature of DIBs still remains unclear. This article reviews the history of the detections of DIBs in the Milky Way and external galaxies,the major observational characteristics of DIBs,the correlations or anti-correlations among DIBs or between DIBs and other interstellar features(e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise),and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  17. The HI absorption "Zoo"

    Science.gov (United States)

    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-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) detections, which are associated with gas-rich mergers, we find three new cases of profiles with blueshifted broad wings (with FW20 ≳ 500 km s-1) in high radio power AGN. These detections are good candidates for being HI outflows. Together with the known cases of outflows already included in the sample (3C 293 and

  18. Assessing the Atmospheric Impact of CF3CClH2 (HCFC-133a): Laboratory Measurements of OH Kinetics and UV and Infrared Absorption Spectra Combined with Model Calculations

    Science.gov (United States)

    McGillen, M.; Bernard, F.; Fleming, E. L.; Jackman, C. H.; Burkholder, J. B.

    2014-12-01

    CF3CClH2 (HCFC-133a) was recently detected in the atmosphere and its atmospheric mixing ratio has quadrupled over the last 10 years. As expected for this class of compound, HCFC-133a is both an ozone-depleting substance and a greenhouse gas. Precise knowledge of its atmospheric degradation and radiative efficiency is critical to understanding its effect upon the atmosphere. The predominant atmospheric loss process for HCFC-133a is via reaction with the OH radical, where the rate coefficient for this reaction is poorly constrained, especially below room temperature. UV photolysis is a minor loss process, although large discrepancies exist among the reported spectrum measurements. The infrared spectrum of HCFC-133a is presently not available in the literature. The primary focus of this work was to reduce the uncertainties in the atmospheric loss processes of HCFC-133a and its radiative efficiency. Rate coefficient measurements for the OH + HCFC-133a reaction over the temperature range 233-397 K will be reported. In addition, UV absorption spectrum measurements over the wavelength (184.95-240 nm) and temperature (213-323 K) ranges and infrared absorption measurements from 500-4000 cm-1 will be reported. These results are used in 2-D atmospheric model calculations to quantify the atmospheric loss processes, atmospheric lifetime, ozone depletion potential, radiative efficiency, and global warming potential of HCFC-133a. These important metrics will enable informed policy decisions regarding HCFC-133a.

  19. New in vitro dermal absorption database and the prediction of dermal absorption under finite conditions for risk assessment purposes

    NARCIS (Netherlands)

    Buist, H.E.; Burgsteden, J.A. van; Freidig, A.P.; Maas, W.J.M.; Sandt, J.J.M. van de

    2010-01-01

    Most QSARs for dermal absorption predict the permeability coefficient, Kp, of a molecule, which is valid for infinite dose conditions. In practice, dermal exposure mostly occurs under finite dose conditions. Therefore, a simple model to predict finite dose dermal absorption from infinite

  20. Interpretation of NO2 absorption in twilight sky spectra

    Science.gov (United States)

    McMahon, B. B.

    1984-07-01

    A multiple scattering model has been developed to calculate nitrogen dioxide (NO2) absorption in the light from the zenith sky during twilight. Model studies show that this absorption is not very sensitive to the atmospheric temperature profile or to tropospheric NO2. The model was used to interpret some ground-based measurements of NO2 sky absorption. Values for the total stratospheric column amount vary from 2 to 12 x 10 to the 15th molec/sq cm, and the mean altitude of the stratospheric concentration profile is around 35 km. These observations are in broad agreement with those of other workers.

  1. Absorption intestinale des vitamines liposolubles

    OpenAIRE

    Reboul Emmanuelle

    2011-01-01

    The molecular mechanisms of fat-soluble vitamin intestinal absorption remain partly unknown, despite the fact that a better understanding of this process would certainly allow to improve their bioavailability. If their digestion-absorption process follows the fate of lipids globally, the recent discovery of membranes proteins involved in their absorption questioned the established dogmas. These new data should be taken into account to avoid dietary or drug interactions that may limit some fat...

  2. Simulating Ru L3-Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Kuiken, Benjamin E. Van; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-04-26

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  3. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries Ⅰ. Absorption of Hydrogen by Hydrogen Storage Alloy MlNi5 Suspended in Benzene

    Institute of Scientific and Technical Information of China (English)

    安越; 陈长聘; 徐国华; 蔡官明; 王启东

    2002-01-01

    The absorption of hydrogen was studied in metal hydride slurry, which is formed by benzene and hydrogen storage alloy powder. The influence of temperature on the rate of absorption was discussed using three-phase mass transfer model. It is also concluded that the suitable absorption temperature is 313 K.

  5. Potassium emission absorption system. Topical report 12

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Coherent single-photon absorption by single emitters coupled to 1D nanophotonic waveguides

    DEFF Research Database (Denmark)

    Chen, Yuntian; Wubs, Martijn; Mørk, Jesper;

    2012-01-01

    We have derived an efficient model that allows calculating the dynamical single-photon absorption of an emitter coupled to a waveguide. We suggest a novel and simple structure that leads to strong single-photon absorption.......We have derived an efficient model that allows calculating the dynamical single-photon absorption of an emitter coupled to a waveguide. We suggest a novel and simple structure that leads to strong single-photon absorption....

  7. Evaluation of time-resolved multi-distance methods to retrieve absorption and reduced scattering coefficients of adult heads in vivo: Optical parameters dependences on geometrical structures of the models used to calculate reflectance

    Science.gov (United States)

    Tanifuji, T.

    2016-03-01

    Time-resolved multi-distance measurements are studied to retrieve absorption and reduced scattering coefficients of adult heads, which have enough depth sensitivity to determine the optical parameters in superficial tissues and brain separately. Measurements were performed by putting the injection and collection fibers on the left semi-sphere of the forehead, with the injection fiber placed toward the temporal region, and by moving the collection fiber between 10 and 60 mm from the central sulcus. It became clear that optical parameters of the forehead at all collection fibers were reasonably determined by selecting the appropriate visibility length of the geometrical head models, which is related to head surface curvature at each position.

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

    Science.gov (United States)

    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 absorption and had promotion effect on myricetrin and hyperoside absorption (P absorption of Protocatechuic acid (P 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.

  9. Cadmium absorption inhibitors for soil

    Energy Technology Data Exchange (ETDEWEB)

    Kitamura, S.

    1974-05-25

    Cadmium absorption by soil is one cause of soil pollution. Cadmium adsorption inhibitors were prepared by mixing alginic acid which contained brown algae (Ascophyllum nodosum) and an inorganic material, shell fossils. This mixture was highly effective in preventing cadmium absorption by the soil.

  10. Light absorption by organic carbon from wood combustion

    Directory of Open Access Journals (Sweden)

    Y. Chen

    2010-02-01

    Full Text Available Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While black carbon (BC is highly absorbing, some organic carbon (OC also has significant absorption, especially at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to positive direct aerosol radiative forcing. Quantification of that absorption is necessary so that radiative-transfer models can evaluate the net radiative effect of OC.

    In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble OC contributes to light absorption at both ultraviolet and visible wavelengths. However, a larger portion of the absorption comes from OC that is extractable only by methanol. Absorption spectra of water-soluble OC are similar to literature reports. We compare spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating OC with higher absorption; changing wood temperature from a devolatilizing state of 210 °C to a near-flaming state of 360 °C causes about a factor of four increase in mass-normalized absorption at visible wavelengths. A clear-sky radiative transfer model suggests that, despite the absorption, both high-temperature and low-temperature OC result in negative top-of-atmosphere radiative forcing over a surface with an albedo of 0.19 and positive radiative forcing over bright surfaces. Unless absorption by real ambient aerosol is higher than that measured here, it probably affects global average clear-sky forcing very little, but could be important in energy balances over bright

  11. Intestinal absorption of specific structured triacylglycerols

    DEFF Research Database (Denmark)

    Mu, Huiling; Høy, Carl-Erik

    2001-01-01

    To clarify the intestinal absorption pathway of medium-chain fatty acids from MMM-type structured triaclyglycerols containing both medium- and long-chain fatty acids, we studied the lymphatic transport of 1,3-dioctanoyl-2-linoleoyl-sn- glycerol (8:0/18:2/8:0), 1,3-didecanoyl-2-linoleoyl...... and activated into CoA, and reacylated into triacylglycerols in the enterocyte, The hydrolysis of MLM-type STAG is predominantly partial hydrolysis, whereas part of the STAG can also be hydrolyzed to free glycerol and free fatty acids. - Mu, H., and CE. Hoy. Intestinal absorption of specific structured......-sn-glycerol (10:0/18:2/10:0), and 1,3-didodecanoyl-2-linoleoyl-sn-glycerol (12:0/18:2/12:0) in a rat model. Safflower oil was used in the absorption study in order to compare the absorption of medium- chain fatty acids and long-chain fatty acids, The triacylglycerol species of lymph Lipids were separated...

  12. Microwave peak absorption frequency of liquid

    Institute of Scientific and Technical Information of China (English)

    HAN GuangZe; CHEN MingDong

    2008-01-01

    Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms, and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent), the material will intensively absorb microwave energy. This is also known as resonant absorption, and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work, dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model, the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time, the expression of microwave peak absorption frequency as a func-tion of the material physical structure, rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene, and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material, but also provide a possible guide for the experiment of microwave-assisted extraction.

  13. Microwave peak absorption frequency of liquid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Microwave-assisted extraction is a new effective method which has practical ap-plications in many fields. Microwave heating is one of its physical mechanisms,and it also has the characteristic of selectivity. When the applied microwave fre-quency equals a certain absorption frequency of the material (or specific compo-nent),the material will intensively absorb microwave energy. This is also known as resonant absorption,and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work,dynamic hy-drogen bond energy was included in molecular activation energy; with the liquid cell model,the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and re-laxation time,the expression of microwave peak absorption frequency as a func-tion of the material physical structure,rotational inertia and electrical dipole mo-ment of molecules was established. These theoretical formulas were applied to water and benzene,and the calculated results agree fairly well with the experi-mental data. This work can not only deepen the study of the interaction between microwave and material,but also provide a possible guide for the experiment of microwave-assisted extraction.

  14. Experimental methodology for obtaining sound absorption coefficients

    Directory of Open Access Journals (Sweden)

    Carlos A. Macía M

    2011-07-01

    Full Text Available Objective: the authors propose a new methodology for estimating sound absorption coefficients using genetic algorithms. Methodology: sound waves are generated and conducted along a rectangular silencer. The waves are then attenuated by the absorbing material covering the silencer’s walls. The attenuated sound pressure level is used in a genetic algorithm-based search to find the parameters of the proposed attenuation expressions that include geometric factors, the wavelength and the absorption coefficient. Results: a variety of adjusted mathematical models were found that make it possible to estimate the absorption coefficients based on the characteristics of a rectangular silencer used for measuring the attenuation of the noise that passes through it. Conclusions: this methodology makes it possible to obtain the absorption coefficients of new materials in a cheap and simple manner. Although these coefficients might be slightly different from those obtained through other methodologies, they provide solutions within the engineering accuracy ranges that are used for designing noise control systems.

  15. Effects of flavour absorption on foods and their packaging materials

    OpenAIRE

    Willige, van, R.W.G.

    2002-01-01

    Keywords: flavour absorption, scalping, packaging, food matrix, lldpe, ldpe, pp, pc, pet, pen,b-lactoglobulin, casein, pectin, cmc, lactose, saccharose, oil, modelling, storage, oxygen permeability, taste perception, sensory quality.Absorption of flavour compounds by linear low-density polyethylene (LLDPE) was studied in model systems representing differences in composition of the food matrix. Proteins,b-lactoglobuline and casein, were able to bind flavours, resulting in suppression of absorp...

  16. Modelling the light absorption properties of particulate matter forming organic particles suspended in seawater.Part 1. Model description, classification of organic particles, and example spectra of the light absorption coefficient and the imaginary part of the refractive index of particulate matter for phytoplankton cells and phytoplankton-like particles

    Directory of Open Access Journals (Sweden)

    Bogdan Woźniak

    2005-06-01

    Full Text Available Data on organic substances in the sea are applied to distinguish hypothetical chemical classes and physical types of suspended particulate organic matter (POM in seawater. Spectra of the light absorption coefficients of particulate matter apm(λ and the imaginary refractive index n'p(λ, are assessed for some of these classes and types of POM in seawater, that is, for live phytoplankton cells and phytoplankton-like particles. The spectral characteristics of these coefficients are established and the probable ranges of variability of their absolute magnitudes defined on the basis of the mass-specific coefficients of light absorption by the various organic substances forming the particles. Also presented are mathematical relationships linking the coefficients apm(λ and n'p(λ for the various chemical classes of POM with their physical parameters, such as the relative contents of organic matter, water, air or some other gas. This article is part of a bio-optical study undertaken by the authors, the objective of which is to implement remote sensing techniques in the investigation of Baltic ecosystems (Woźniak et al. 2004.

  17. Solar heating and cooling with absorption refrigeration

    OpenAIRE

    Montlló Casabayó, Gerard

    2010-01-01

    This project is focused on solar heating and cooling installations that use solar thermal energy to produce heat for domestic hot water or space heating, and cooling for air conditioning through absorption refrigeration cycle. The first part of the project is a literature review of said technology. The main components of such installations are described and results and conclusions from existing installations are reviewed. The second part is focused on designing, modelling and simula...

  18. Theoretical modeling of UV-Vis absorption and emission spectra in liquid state systems including vibrational and conformational effects: explicit treatment of the vibronic transitions.

    Science.gov (United States)

    D'Abramo, Marco; Aschi, Massimiliano; Amadei, Andrea

    2014-04-28

    Here, we extend a recently introduced theoretical-computational procedure [M. D'Alessandro, M. Aschi, C. Mazzuca, A. Palleschi, and A. Amadei, J. Chem. Phys. 139, 114102 (2013)] to include quantum vibrational transitions in modelling electronic spectra of atomic molecular systems in condensed phase. The method is based on the combination of Molecular Dynamics simulations and quantum chemical calculations within the Perturbed Matrix Method approach. The main aim of the presented approach is to reproduce as much as possible the spectral line shape which results from a subtle combination of environmental and intrinsic (chromophore) mechanical-dynamical features. As a case study, we were able to model the low energy UV-vis transitions of pyrene in liquid acetonitrile in good agreement with the experimental data. PMID:24784250

  19. Cluster model calculation for X-ray magnetic circular dichroism at rare-earth (R) L sub 2 sub , sub 3 absorption edges in R sub 2 Fe sub 1 sub 4 B

    CERN Document Server

    Asakura, K; Harada, I; Ogasawara, H; Fukui, K; Kotani, A

    2002-01-01

    X-ray magnetic circular dichroism (MCD) at the L sub 2 sub , sub 3 absorption edges for the entire series of rare-earth (RE) elements in R sub 2 Fe sub 1 sub 4 B (R=RE) is studied based on a cluster model including 10 RE and 16 Fe atoms. The cluster model takes into account band effects of RE 5d states, to which the electric dipole transition occurs from the core 2p states, as well as spin polarization of the 5d states due to the interatomic hybridization with the spin polarized Fe 3d states. We also take into account spin and orbital polarization of the 5d states due to the 5d-4f intra-atomic exchange interaction, and the 2p to 4f quadrupole transition. The calculated results are in satisfactory agreement with experimental ones, suggesting that the cluster model calculation provides a new method to calculate quantitatively MCD spectra of RE systems with complicated atomic arrangements. (author)

  20. Gastrointestinal citrate absorption in nephrolithiasis

    Science.gov (United States)

    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.

  1. 班豆在浸泡加工过程中吸水特性的模拟%Modeling of Water Absorption of Pinto Beans During Blanching and Soaking

    Institute of Scientific and Technical Information of China (English)

    潘忠礼

    2002-01-01

    在生产速食干豆过程中,主要包括浸泡、蒸煮和干燥等工序.浸泡的温度和时间直接影响到在浸泡过程中固性物的损失和最终产品的质量.该研究测定了班豆在浸泡过程中在不同温度和时间下的吸水和固性物的损失特性,同时利用数学模型预测了在变温情况下班豆的吸水特性.该研究结果将对生产高质量的速食班豆有一定的指导作用.%Blanching and soaking are essential thermal processing steps in the process of precooked pinto beans. Appropriate blanching and soaking conditions could reduce antinutritional factors, such as trypsin inhibitors, improve the quality of finished products, and reduce processing time and solid losses. The characteristics of water absorption (hydration ratio and moisture content) and solid losses of pinto beans were measured at various temperatures (30 to 100℃) and time periods (5 min to 24 h). It was found that the hydration ratio, moisture content, and solid loss increased with the increased temperature and time. But the rate of water absorption decreased with the increase of time. To obtain high quality product with minimum processing time and solid loss, variable temperature for blanching and soaking is normally used. Models for predicting the hydration ratio and moisture content were developed and validated under variable blanching and soaking temperatures and time periods.

  2. Electro-absorption of silicene and bilayer graphene quantum dots

    Science.gov (United States)

    Abdelsalam, Hazem; Talaat, Mohamed H.; Lukyanchuk, Igor; Portnoi, M. E.; Saroka, V. A.

    2016-07-01

    We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.

  3. Absorption of CH330331, a novel 4-anilinoquinazoline inhibitor of epidermal growth factor receptor tyrosine kinase: comparative studies using in vitro, in situ and in vivo models.

    Science.gov (United States)

    Sun, Haiyan; Bi, Huichang; Huang, Min; Liu, Dong; Qin, Zhenyu

    2010-11-01

    CH330331 is a prototype of a new class of synthetic small molecule tyrosine kinase inhibitors (TKIs). In vitro Caco-2 cell monolayers, the in situ single-pass rat intestinal perfusion (SPIP) technique with mesenteric vein cannulated and an in vivo animal model were employed to investigate its permeability and transepithelial transport mechanisms. The Caco-2 model showed that the transport of CH330331 across the monolayers from the apical (AP) to basolateral (BL) side was 6- to 10-fold higher than that from the BL to AP side. The apparent permeability coefficient (P(app) ) values of CH330331 at 5-20 µg/ml from the AP to BL and from BL to AP side were 5.30-2.21 × 10(-6)  cm/s, with a decrease in P(app) values from the AP to BL side at increased CH330331 concentrations. In the perfused rat intestinal model, a concentration dependent change in permeability was detected where P(blood) at 5 µg/ml (1.66 ± 0.69 × 10(-6)  cm/s) and 10 µg/ml (1.80 ± 0.45 × 10(-6)  cm/s) was significantly different from P(blood) at 20 µg/ml (0.98 ± 0.31 × 10(-6)  cm/s, prat. All the results confirmed that the transepithelial transport of CH330331 was rapid and saturable, which might involve an active mechanism. The oral bioavailability of CH330331 was relatively high in vivo.

  4. Total light absorption in graphene

    CERN Document Server

    Thongrattanasiri, Sukosin; de Abajo, F Javier Garcia

    2011-01-01

    We demonstrate that 100% light absorption can take place in a single patterned sheet of doped graphene. General analysis shows that a planar array of small lossy particles exhibits full absorption under critical-coupling conditions provided the cross section of each individual particle is comparable to the area of the lattice unit-cell. Specifically, arrays of doped graphene nanodisks display full absorption when supported on a substrate under total internal reflection, and also when lying on a dielectric layer coating a metal. Our results are relevant for infrared light detectors and sources, which can be made tunable via electrostatic doping of graphene.

  5. Quantum model of a solid-state spin qubit: Ni cluster on a silicon surface by the generalized spin Hamiltonian and X-ray absorption spectroscopy investigations

    Energy Technology Data Exchange (ETDEWEB)

    Farberovich, Oleg V. [School of Physics and Astronomy, Beverly and Raymond Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Research Center for Nanoscale Structure of Matter, Southern Federal University, Zorge 5, 344090 Rostov-on-Don (Russian Federation); Voronezh State University, Voronezh 394000 (Russian Federation); Mazalova, Victoria L., E-mail: mazalova@sfedu.ru [Research Center for Nanoscale Structure of Matter, Southern Federal University, Zorge 5, 344090 Rostov-on-Don (Russian Federation); Soldatov, Alexander V. [Research Center for Nanoscale Structure of Matter, Southern Federal University, Zorge 5, 344090 Rostov-on-Don (Russian Federation)

    2015-11-15

    We present here the quantum model of a Ni solid-state electron spin qubit on a silicon surface with the use of a density-functional scheme for the calculation of the exchange integrals in the non-collinear spin configurations in the generalized spin Hamiltonian (GSH) with the anisotropic exchange coupling parameters linking the nickel ions with a silicon substrate. In this model the interaction of a spin qubit with substrate is considered in GSH at the calculation of exchange integrals J{sub ij} of the nanosystem Ni{sub 7}–Si in the one-electron approach taking into account chemical bonds of all Si-atoms of a substrate (environment) with atoms of the Ni{sub 7}-cluster. The energy pattern was found from the effective GSH Hamiltonian acting in the restricted spin space of the Ni ions by the application of the irreducible tensor operators (ITO) technique. In this paper we offer the model of the quantum solid-state N-spin qubit based on the studying of the spin structure and the spin-dynamics simulations of the 3d-metal Ni clusters on the silicon surface. The solution of the problem of the entanglement between spin states in the N-spin systems is becoming more interesting when considering clusters or molecules with a spectral gap in their density of states. For quantifying the distribution of the entanglement between the individual spin eigenvalues (modes) in the spin structure of the N-spin system we use the density of entanglement (DOE). In this study we have developed and used the advanced high-precision numerical techniques to accurately assess the details of the decoherence process governing the dynamics of the N-spin qubits interacting with a silicon surface. We have studied the Rabi oscillations to evaluate the N-spin qubits system as a function of the time and the magnetic field. We have observed the stabilized Rabi oscillations and have stabilized the quantum dynamical qubit state and Rabi driving after a fixed time (0.327 μs). The comparison of the energy

  6. Quantum Entanglement Molecular Absorption Spectrum Simulator

    Science.gov (United States)

    Nguyen, Quang-Viet; Kojima, Jun

    2006-01-01

    Quantum Entanglement Molecular Absorption Spectrum Simulator (QE-MASS) is a computer program for simulating two photon molecular-absorption spectroscopy using quantum-entangled photons. More specifically, QE-MASS simulates the molecular absorption of two quantum-entangled photons generated by the spontaneous parametric down-conversion (SPDC) of a fixed-frequency photon from a laser. The two-photon absorption process is modeled via a combination of rovibrational and electronic single-photon transitions, using a wave-function formalism. A two-photon absorption cross section as a function of the entanglement delay time between the two photons is computed, then subjected to a fast Fourier transform to produce an energy spectrum. The program then detects peaks in the Fourier spectrum and displays the energy levels of very short-lived intermediate quantum states (or virtual states) of the molecule. Such virtual states were only previously accessible using ultra-fast (femtosecond) laser systems. However, with the use of a single-frequency continuous wave laser to produce SPDC photons, and QEMASS program, these short-lived molecular states can now be studied using much simpler laser systems. QE-MASS can also show the dependence of the Fourier spectrum on the tuning range of the entanglement time of any externally introduced optical-path delay time. QE-MASS can be extended to any molecule for which an appropriate spectroscopic database is available. It is a means of performing an a priori parametric analysis of entangled photon spectroscopy for development and implementation of emerging quantum-spectroscopic sensing techniques. QE-MASS is currently implemented using the Mathcad software package.

  7. Effect of antibiotic treatment on fat absorption in mice with cystic fibrosis

    NARCIS (Netherlands)

    Wouthuyzen-Bakker, Marjan; Bijvelds, Marcel J. C.; de Jonge, Hugo R.; De Lisle, Robert C.; Burgerhof, Johannes G. M.; Verkade, Henkjan J.

    2012-01-01

    INTRODUCTION: Improving fat absorption remains a challenge in cystic fibrosis (CF). Antibiotics (AB) treatment has been shown to improve body weight in CF mice. The mechanism may include improvement in fat absorption. We aimed to determine the effect of AB on fat absorption in two CF mouse models. R

  8. NLP modeling for the optimization of LiBr-H2O absorption refrigeration systems with exergy loss rate, heat transfer area, and cost as single objective functions

    DEFF Research Database (Denmark)

    Mussati, Sergio F.; Gernaey, Krist; Morosuk, Tatiana;

    2016-01-01

    and all stream temperatures, while the optimal solution obtained by minimization of the total heat transfer area provides the lower bounds for these model variables, to solve a cost optimization problem. The minimization of the total exergy loss rate by varying parametrically the available total heat...... to the theoretical value. The optimal solutions corresponding to the theoretical and the practical upper bound values for the total heat transfer area (100 m2 and 61 m2, respectively) as well as the optimal solution obtained by minimization of the total annual cost are discussed for a case study considering...... exergy loss rate, the total heat transfer area, and the total annual cost of the system. It was found that the optimal solution obtained by minimization of the total exergy loss rate provides “theoretical” upper bounds not only for the total heat transfer area of the system but also for each process unit...

  9. Absorption of impinging water droplet in porous stones.

    Science.gov (United States)

    Lee, J B; Radu, A I; Vontobel, P; Derome, D; Carmeliet, J

    2016-06-01

    This paper presents an experimental investigation and numerical analysis of the absorption of water droplets impacting porous stones. The absorption process of an impinging droplet is here fully characterized from spreading to evaporation in terms of absorbed mass during droplet depletion and moisture content distribution in a time-resolved manner for three different natural stones. High-speed imaging and neutron radiography are used to quantify moisture absorption in porous stones of varying moisture properties from deposition until depletion. During impact and spreading, the droplet exhibits a dynamic non-wetting behavior. At maximum spreading, the droplet undergoes pinning, resulting into the contact radius remaining constant until droplet depletion. Absorption undergoes two phases: initially, absorption is hindered due a contact resistance attributed to entrapped air; afterwards, a more perfect capillary contact occurs and absorption goes on until depletion, concurrently with evaporation and further redistribution. A finite-element numerical model for isothermal unsaturated moisture transport in porous media captures the phases of mass absorption in good agreement with the experimental data. Droplet spreading and absorption are highly determined by the impact velocity of the droplet, while moisture content redistribution after depletion is much less dependent on impact conditions. PMID:26975034

  10. Reproducibility of The Random Incidence Absorption Coefficient Converted From the Sabine Absorption Coefficient

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Chang, Ji-ho

    2015-01-01

    Absorption coefficients measured in reverberation chambers, Sabine absorption coefficients, suffer from two major problems. Firstly, they sometimes exceed unity. Secondly, the reproducibility of the Sabine absorption coefficients is quite poor, meaning that the Sabine absorption coefficients vary...

  11. OZONE ABSORPTION IN RAW WATERS

    Directory of Open Access Journals (Sweden)

    LJILJANA TAKIĆ

    2008-03-01

    Full Text Available The ozone absorption in raw water entering the main ozonization step at the Belgrade drinking water supply plant was investigated in a continuous stirred tank reactor (CSTR. A slow chemical reaction rate of dissolved ozone and pollutants present in raw water have been experimentally determined. The modified Hatta number was defined and calculated as a criterion which determines whether and to which extent the reactions of ozone and pollutants influence the rate of the pure physical ozone absorption.

  12. Incomplete intestinal absorption of fructose.

    OpenAIRE

    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 ...

  13. Absorption Of Dietary Lipid Components

    OpenAIRE

    Abdulkadir Hurşit

    2015-01-01

    Although the digestion and absorption of lipids that are necessary for the survival of living organisms are well known in general terms, nevertheless how different lipids to be digested, how it is distributed into the bloodstream, and how to be used by the cells, are unknown issues by most non specialist people. In recent years, knowledge of lipid digestion and absorption has expanded considerably. More insight has been gained in the mechanism of action of H + pump as a transport system in fa...

  14. Detection of water vapour absorption around 363nm in measured atmospheric absorption spectra and its effect on DOAS evaluations

    Science.gov (United States)

    Lampel, Johannes; Polyansky, Oleg. L.; Kyuberis, Alexandra A.; Zobov, Nikolai F.; Tennyson, Jonathan; Lodi, Lorenzo; Pöhler, Denis; Frieß, Udo; Platt, Ulrich; Beirle, Steffen; Wagner, Thomas

    2016-04-01

    Water vapour is known to absorb light from the microwave region to the blue part of the visible spectrum at a decreasing magnitude. Ab-initio approaches to model individual absorption lines of the gaseous water molecule predict absorption lines until its dissociation limit at 243 nm. We present first evidence of water vapour absorption at 363 nm from field measurements based on the POKAZATEL absorption line list by Polyansky et al. (2016) using data from Multi-Axis differential optical absorption spectroscopy (MAX-DOAS) and Longpath (LP)-DOAS measurements. The predicted absorptions contribute significantly to the observed optical depths with up to 2 × 10‑3. Their magnitude correlates well (R2 = 0.89) to simultaneously measured well-established water vapour absorptions in the blue spectral range from 452-499 nm, but is underestimated by a factor of 2.6 ± 0.6 in the ab-initio model. At a spectral resolution of 0.5nm this leads to a maximum absorption cross-section value of 5.4 × 10‑27 cm2/molec at 362.3nm. The results are independent of the employed cross-section data to compensate for the overlayed absorption of the oxygen dimer O4. The newly found absorption can have a significant impact on the spectral retrieval of absorbing trace-gas species in the spectral range around 363 nm. Its effect on the spectral analysis of O4, HONO and OClO are discussed.

  15. Subgap Absorption in Conjugated Polymers

    Science.gov (United States)

    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 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.

  16. Drug absorption in vitro model: filter-immobilized artificial membranes. 2. Studies of the permeability properties of lactones in Piper methysticum Forst.

    Science.gov (United States)

    Avdeef, A; Strafford, M; Block, E; Balogh, M P; Chambliss, W; Khan, I

    2001-12-01

    The assessment of transport properties of 23 drug and natural product molecules was made using the in vitro model based on filter-immobilized artificial membranes (filter-IAM), assembled from phosphatidylcholine in dodecane, in buffer solutions at pH 7.4. Five of the compounds were lactones extracted from the roots of the kava-kava plant. Experiments were designed to test the effects of stirring (0-600 rpm) during assays and the effects of varying the assay times (2-15 h). The highly mobile kava lactones permeated in the order dihydromethisticin (40)>yangonin (37)>kavain (34)>methisticin (32)>desmethoxyyangonin (26), the numbers in parentheses being the measured effective permeabilities in units of 10(-6) cm/s. By comparison, commercial drugs ranked: phenazopyridine (35)>testosterone (19)>propranolol (13)>ketoconazole (6.3)>piroxicam (2.2)>caffeine (1.7)>metoprolol (0.8)>terbutaline (0.01). In addition to permeability measurements, membrane retention of compounds was determined. Yangonin, desmethoxyyangonin, ketoconazole, and phenazopyridine were more than 60% retained by the artificial membranes containing phospholipids. Stirring during assay significantly increased the observed permeabilities for highly mobile molecules, but had minimal impact on the poorly permeable molecules. The influence of hydrogen bonding was explored by determining permeabilities using filters coated with dodecane free of phospholipids. In the filter-IAM method, concentrations were determined by microtitre plate UV spectrophotometry and by LC-MS. Higher-throughput was achieved with direct UV by the use of 96-well microtitre plate formats and with LC-MS by the use of cassette dosing (five-in-one). PMID:11684401

  17. Comparison of box-air-mass-factors and radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS geometries calculated from different UV/visible radiative transfer models

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2007-01-01

    Full Text Available The results of a comparison exercise of radiative transfer models (RTM of various international research groups for Multiple AXis Differential Optical Absorption Spectroscopy (MAX-DOAS viewing geometry are presented. Besides the assessment of the agreement between the different models, a second focus of the comparison was the systematic investigation of the sensitivity of the MAX-DOAS technique under various viewing geometries and aerosol conditions. In contrast to previous comparison exercises, box-air-mass-factors (box-AMFs for different atmospheric height layers were modelled, which describe the sensitivity of the measurements as a function of altitude. In addition, radiances were calculated allowing the identification of potential errors, which might be overlooked if only AMFs are compared. Accurate modelling of radiances is also a prerequisite for the correct interpretation of satellite observations, for which the received radiance can strongly vary across the large ground pixels, and might be also important for the retrieval of aerosol properties as a future application of MAX-DOAS. The comparison exercises included different wavelengths and atmospheric scenarios (with and without aerosols. The strong and systematic influence of aerosol scattering indicates that from MAX-DOAS observations also information on atmospheric aerosols can be retrieved. During the various iterations of the exercises, the results from all models showed a substantial convergence, and the final data sets agreed for most cases within about 5%. Larger deviations were found for cases with low atmospheric optical depth, for which the photon path lengths along the line of sight of the instrument can become very large. The differences occurred between models including full spherical geometry and those using only plane parallel approximation indicating that the correct treatment of the Earth's sphericity becomes indispensable. The modelled box-AMFs constitute an

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

    Science.gov (United States)

    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

  19. Laser absorption via QED cascades in counter propagating laser pulses

    CERN Document Server

    Grismayer, Thomas; Martins, Joana L; Fonseca, Ricardo A; Silva, Luis O

    2015-01-01

    A model for laser light absorption in electron-positron plasmas self-consistently created via QED cascades is described. The laser energy is mainly absorbed due to hard photon emission via nonlinear Compton scattering. The degree of absorption depends on the laser intensity and the pulse duration. The QED cascades are studied with multi-dimensional particle-in-cell simulations complemented by a QED module and a macro-particle merging algorithm that allows to handle the exponential growth of the number of particles. Results range from moderate-intensity regimes ($\\sim$ 10 PW) where the laser absorption is negligible, to extreme intensities (> 100 PW) where the degree of absorption reaches 80%. Our study demonstrates good agreement between the analytical model and simulations. The expected properties of the hard photon emission and the generated pair-plasma are investigated, and the experimental signatures for near-future laser facilities are discussed.

  20. Laser-supported solid-state absorption fronts in silica

    Science.gov (United States)

    Carr, C. W.; Bude, J. D.; Demange, P.

    2010-11-01

    We develop a model based on simulation and extensive experimentation that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm2 ) laser exposure. Both experiments and simulations show that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. We show that these absorption fronts naturally result from the combination of high-temperature-activated deep subband-gap optical absorptivity, free-electron transport, and thermal diffusion in defect-free silica for temperatures up to 15000K and pressures critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

  1. Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-thick Populations

    Science.gov (United States)

    Ueda, Yoshihiro; Akiyama, Masayuki; Hasinger, Günther; Miyaji, Takamitsu; Watson, Michael G.

    2014-05-01

    We present the most up to date X-ray luminosity function (XLF) and absorption function of active galactic nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5-2 keV) and/or hard (>2 keV) band. We utilize a maximum likelihood method to reproduce the count rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broadband spectra of AGNs, including reflection components from tori based on the luminosity- and redshift-dependent unified scheme. We find that the shape of the XLF at z ~ 1-3 is significantly different from that in the local universe, for which the luminosity-dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-ray background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be ≈0.5-1.6 to produce the 20-50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.

  2. Transport of trans-tiliroside (kaempferol-3-β-D-(6"-p-coumaroyl-glucopyranoside) and related flavonoids across Caco-2 cells, as a model of absorption and metabolism in the small intestine.

    Science.gov (United States)

    Luo, Zijun; Morgan, Michael R A; Day, Andrea J

    2015-01-01

    1. Absorption and metabolism of tiliroside (kaempferol 3-β-D-(6"-p-coumaroyl)-glucopyranoside) and its related compounds kaempferol, kaempferol-3-glucoside and p-coumaric acid were investigated in the small intestinal Caco-2 cell model. Apparent permeation (Papp) was determined as 0.62 × 10(-6) cm/s, 3.1 × 10(-6) cm/s, 0 and 22.8 × 10(-6) cm/s, respectively. 2. Mechanistic study showed that the transportation of tiliroside, kaempferol-3-glucoside and p-coumaric acid in Caco-2 model were transporter(s) involved, while transportation of kaempferol was solely by passive diffusion mechanism. 3. Efflux transporters, multi-drug-resistance-associated protein-2 (MRP2), were shown to play a role in limiting the uptake of tiliroside. Inhibitors of MRP2, (MK571 and rifampicin) and co-incubation with kaempferol (10 μM), increased transfer from the apical to the basolateral side by three to five fold. 4. Metabolites of kaempferol-3-glucoside and p-coumaric acid were not detected in the current Caco-2 model, while tiliroside was metabolised to a limited extent, with two tiliroside mono-glucuronides identified; and kaempferol was metabolised to a higher extent, with three mono-glucuronides and two mono-sulfates identified. 5. In conclusion, tiliroside was metabolised and transported across Caco-2 cell membrane to a limited extent. Transportation could be increased by applying MRP2 inhibitors or co-incubation with kaempferol. It is proposed that tiliroside can be absorbed by human; future pharmacokinetics studies are warranted in order to determine the usefulness of tiliroside as a bioactive agent.

  3. Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations

    CERN Document Server

    Ueda, Yoshihiro; Hasinger, Guenther; Miyaji, Takamitsu; Watson, Michael G

    2014-01-01

    We present the most up-to-date X-ray luminosity function (XLF) and absorption function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5--2 keV) and/or hard ($>2$ keV) band. We utilize a maximum likelihood method to reproduce the count-rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broad band spectra of AGNs including reflection components from tori based on the luminosity and redshift dependent unified scheme. We find that the shape of the XLF at $z \\sim 1-3$ is significantly different from that in the local universe, for which the luminosity dependent density evolution model gives much better description...

  4. Near-infrared free carrier absorption in heavily doped silicon

    Energy Technology Data Exchange (ETDEWEB)

    Baker-Finch, Simeon C., E-mail: simeon.bakerfinch@gmail.com [School of Engineering, Australian National University, Canberra, ACT 0200 (Australia); PV Lighthouse, Coledale, NSW 2515 (Australia); McIntosh, Keith R. [PV Lighthouse, Coledale, NSW 2515 (Australia); Yan, Di; Fong, Kean Chern; Kho, Teng C. [School of Engineering, Australian National University, Canberra, ACT 0200 (Australia)

    2014-08-14

    Free carrier absorption in heavily doped silicon can have a significant impact on devices operating in the infrared. In the near infrared, the free carrier absorption process can compete with band to band absorption processes, thereby reducing the number of available photons to optoelectronic devices such as solar cells. In this work, we fabricate 18 heavily doped regions by phosphorus and boron diffusion into planar polished silicon wafers; the simple sample structure facilitates accurate and precise measurement of the free carrier absorptance. We measure and model reflectance and transmittance dispersion to arrive at a parameterisation for the free carrier absorption coefficient that applies in the wavelength range between 1000 and 1500 nm, and the range of dopant densities between ∼10{sup 18} and 3 × 10{sup 20} cm{sup −3}. Our measurements indicate that previously published parameterisations underestimate the free carrier absorptance in phosphorus diffusions. On the other hand, published parameterisations are generally consistent with our measurements and model for boron diffusions. Our new model is the first to be assigned uncertainty and is well-suited to routine device analysis.

  5. Absorption characteristics of bacteriorhodopsin molecules

    Indian Academy of Sciences (India)

    H K T Kumar; K Appaji Gowda

    2000-03-01

    The bacteriorhodopsin molecule absorbs light and undergoes a series of structural transformation following a well-defined photocycle. The complex photocycle is transformed to an equivalent level diagram by considering the lifetime of the intermediate states. Assuming that only and states are appreciably populated at any instant of time, the level diagram is further simplified to two-level system. Based on the rate equations for two-level system, an analytic expression for the absorption coefficient of bacteriorhodopsin molecule is derived. It is applied to study the behaviour of absorption coefficient of bacteriorhodopsin film in the visible wavelength region of 514 nm. The dependence of absorption coefficient of bacteriorhodopsin film on the thickness of the film, total number density of active molecules and initial number density of molecules in -state is presented in the graphical form.

  6. Light absorption by organic carbon from wood combustion

    Directory of Open Access Journals (Sweden)

    Y. Chen

    2009-09-01

    Full Text Available Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While BC is highly absorbing, some organic compounds also have significant absorption, which is greater at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to direct aerosol radiative forcing.

    In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble organic carbon contributed to light absorption at both ultraviolet and visible wavelengths. However, a larger portion came from organic carbon that is extractable only by methanol. The spectra of water-soluble organic carbon are similar to others in the literature. We compared spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating organic aerosol with higher absorption, causing about a factor of four increase in mass-normalized absorption at visible wavelengths. A simple model suggests that, despite the absorption, both high-temperature and low-temperature carbon have negative climate forcing over a surface with average albedo.

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

    Science.gov (United States)

    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 inhibition effect on protocatechuic acid absorption and had promotion effect on myricetrin and hyperoside absorption (P 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

  8. Absorption of focused light by spherical plasmas

    International Nuclear Information System (INIS)

    For light focused on spherical plasmas, we obtain new results giving the power absorbed by inverse bremsstrahlung and resonance absorption as a function of the focusing scheme. For a given beam profile and lens, there is an optimum focus to maximize total absorption. Linearly polarized beams lead to asymmetric absorption. Good agreement with experimental absorption and scattered light data is obtained

  9. Diabetic lipohypertrophy delays insulin absorption.

    Science.gov (United States)

    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.

  10. Quasistellar Objects Intervening Absorption Lines

    CERN Document Server

    Charlton, J C; Charlton, Jane C.; Churchill, Christopher W.

    2000-01-01

    We briefly review, at a level appropriate for graduate students and non-specialists, the field of quasar absorption lines (QALs). Emphasis is on the intervening absorbers. We present the anatomy of a quasar spectrum due to various classes of intervening absorption systems, and a brief historical review of each absorber class (Lyman-alpha forest and Lyman limit systems, and metal-line and damped Lyman-alpha absorbers). We also provide several heuristic examples on how the physical properties of both the intergalactic medium and the gaseous environments associated with earlier epoch galaxies can be inferred from QALs. The evolution of these environments from z=4 are discussed.

  11. Absorption Efficiency of Receiving Antennas

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Frandsen, Aksel

    2005-01-01

    A receiving antenna with a matched load will always scatter some power. This paper sets an upper and a lower bound on the absorption efficiency (absorbed power over sum of absorbed and scattered powers), which lies between 0 and 100% depending on the directivities of the antenna and scatter...... patterns. It can approach 100% as closely as desired, although in practice this may not be an attractive solution. An example with a small endfire array of dipoles shows an efficiency of 93%. Several examples of small conical horn antennas are also given, and they all have absorption efficiencies less than...

  12. Phytases for improved iron absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Meyer, Anne S.

    2016-01-01

    Phytase enzymes present an alternative to iron supplements, because they have been shown to improve iron absorption by means of catalysing the degradation of a potent iron absorption inhibitor: phytic acid. Phytic acid is a hexaphosphate of inositol and is particularly prevalent in cereal grains......, where it serves as a storage molecule for phosphorous. Phytic acid is also associated with minerals. The minerals are bound by chelation to the negatively charged phosphate groups in phytic acid. Phytases catalyse the dephosphorylation of phytic acid, thus releasing bound minerals to make them available...

  13. Aerosol Absorption Measurements in MILAGRO.

    Science.gov (United States)

    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

  14. Absorption heat cycles. An experimental and theoretical study

    International Nuclear Information System (INIS)

    A flow sheeting programme, SHPUMP, was developed for simulating different absorption heat cycles. The programme consists of ten different modules which allow the user to construct his own absorption cycle. The ten modules configurate evaporators, absorbers, generators, rectifiers, condensers, solution heat exchangers, pumps, valves, mixers and splitters. Seven basic and well established absorption cycles are available in the configuration data base of the programme. A new Carnot model is proposed heat cycles. Together with exergy analysis, general equations for the Carnot coefficient of performance and equations for thermodynamic efficiency, exergetic efficiency and exergy index, are derived, discussed and compared for both absorption heat pumps and absorption heat transformers. Utilizing SHPUMP, simulation results are presented for different configurations where absorption heat cycles are suggested to be incorporated in three different unit operations within both pulp and paper and oleochemical industries. One of the application studies reveled that an absorption heat transformer incorporated with an evaporation plant in a major pulp and paper industry, would save 18% of the total prime energy consumption in one of the evaporation plants. It was also concluded that installing an absorption heat pump in a paper drying plant would result in steam savings equivalent to 12 MW. An experimental absorption heat transformer unit operating with self-circulation has been modified and thoroughly tested. A reference heat transformer plant has been designed and installed in a major pulp and paper mill where it is directly incorporated with one of the evaporation plants. Preliminary plant operation data are presented. 72 refs, 63 figs, 33 tabs

  15. Transient light absorption induced in glassby femtosecond laser pulses

    International Nuclear Information System (INIS)

    The dynamics of the transient light absorption induced in K8 optical glass by filamented femtosecond laser pulses have been studied using time-resolved transmitted-light microscopy at wavelengths from 450 to 700 nm. The transient absorption measured as a function of probe beam wavelength is compared to that predicted by the Drude plasma model. We conclude that, just 450 fs after a pump pulse, the transient absorption is dominated by transient electronic states, presumably, self-trapped excitons, with an excitation energy of 2.6 - 2.7 eV. These states are filled with free-carriers from a long-lived plasma, which acts as a 'carrier reservoir'. The relaxation of transient absorption has two components. The slow component, with τ1 ∼ 17-17.5 ps, is governed by the plasma thermalisation time, whereas the second, with τ1 >> 300 ps, is determined by the plasma lifetime. (nonlinear optical phenomena)

  16. Communication: XUV transient absorption spectroscopy of iodomethane and iodobenzene photodissociation

    Science.gov (United States)

    Drescher, L.; Galbraith, M. C. E.; Reitsma, G.; Dura, J.; Zhavoronkov, N.; Patchkovskii, S.; Vrakking, M. J. J.; Mikosch, J.

    2016-07-01

    Time-resolved extreme ultraviolet (XUV) transient absorption spectroscopy of iodomethane and iodobenzene photodissociation at the iodine pre-N4,5 edge is presented, using femtosecond UV pump pulses and XUV probe pulses from high harmonic generation. For both molecules the molecular core-to-valence absorption lines fade immediately, within the pump-probe time-resolution. Absorption lines converging to the atomic iodine product emerge promptly in CH3I but are time-delayed in C6H5I. We attribute this delay to the initial π → σ* excitation in iodobenzene, which is distant from the iodine reporter atom. We measure a continuous shift in energy of the emerging atomic absorption lines in CH3I, attributed to relaxation of the excited valence shell. An independent particle model is used to rationalize the observed experimental findings.

  17. Resonant upscattering effects on 238U absorption rates

    International Nuclear Information System (INIS)

    The new requirements of accuracy in reactor physics calculations justify a review of the current models, like that one adopted in the cross-section processing, for a better evaluation of the keff and the resonant absorption rates. In this context, the aim of this paper is to investigate the effects of the free gas kernel developed by Sanchez on the 238U absorption rates. Homogeneous medium tests point out the increase of the absorption rates in the left wing of the resonances due to the upscattering produced by the new kernel. Heterogeneous tests show that the absorption in the left wing of the resonances is mostly affected by the scattering anisotropy in the laboratory system. (author)

  18. INVESTIGATION ON SOUND ABSORPTION PROPERTIES OF KAPOK FIBERS

    Institute of Scientific and Technical Information of China (English)

    Hai-fan Xiang; Dong Wang; Hui-chao Liu; Ning Zhao; Jian Xu

    2013-01-01

    Sound absorption properties of natural kapok fibers have been investigated.Kapok fibrous assemblies with different bulk density,thickness,fiber length and orientation were manufactured,and their acoustical performances were evaluated by using an impedance tube instrument.Results show that the kapok fiber has excellent acoustical damping performance due to its natural hollow structure,and the sound absorption coefficients of kapok fibrous assemblies are significantly affected by the bulk density,thickness and arrangement of kapok fibers but less dependent on the fiber length.Compared with assemblies of commercial glass wool and degreasing cotton fibers,the kapok fiber assemblies with the same thickness but much smaller bulk density may have the similar sound absorption coefficients.Theoretical modelling of the acoustical damping performance of kapok fibers shows a good agreement with the experimental data.All the results demonstrate that kapok fiber is a promising light and environment-friendly sound absorption material.

  19. Sound absorption performance of natural fibers and their composites

    Institute of Scientific and Technical Information of China (English)

    YANG WeiDong; LI Yan

    2012-01-01

    This research aimed to study the sound absorption properties of natural fibers and their reinforced composites.Sound absorption coefficients of three types of natural fibers,i.e.,ramie,flax and jute fibers and their composites were measured by the two-microphone transfer function technique in the impedance tube.The results were compared with synthetic fibers and their composites.It was found that both natural fibers and their composites had superior capability of noise reduction.The multi-scale and hollow lumen structures of natural fibers contributed to the high sound absorption performance.Moreover,the sound absorption properties of these natural fibers were also calculated by the Delany-Bazley and Garai-Pompoli models.They showed good agreement with the experimental data.It was concluded that multi-functional composite materials can be made by natural fibers so that both the mechanical and acoustical functions can be achieved.

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

    Science.gov (United States)

    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.

  1. Absorption heat pump for space applications

    Science.gov (United States)

    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.

  2. Exercise, Intestinal Absorption, and Rehydration

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ KEYPOINTS 1. The proximal small intestine (duodenum & jejunum) is the primary site of fluid absorption. It absorbs about 50% to 60% of any given fluid load. The colon or large intestine absorbs approximately 80 to 90% of the fluid it receives, but accounts for only about 15% of the total fluid load.

  3. S matrix for absorptive Hamiltonians

    International Nuclear Information System (INIS)

    The existence of a matrix S such that SS = 1 in the presence of absorption is demonstrated. In the limit a of hermitian Hamiltonian the unitarity conditions SS = 1 is recovered. A dispersion relation for forward scattering is derived and the properties of the reactance matrices K and K are obtained. It is shown that K = K

  4. QSO Absorption Lines from QSOs

    CERN Document Server

    Bowen, D V; Ménard, B; Chelouche, D; Inada, N; Oguri, M; Richards, G T; Strauss, M A; Vanden Berk, Daniel E; York, D G; Bowen, David V.; Hennawi, Joseph F.; Menard, Brice; Chelouche, Doron; Inada, Naohisa; Oguri, Masamune; Richards, Gordon T.; Strauss, Michael A.; Berk, Daniel E. Vanden; York, Donald G.

    2006-01-01

    We present the results of a search for metal absorption lines in the spectra of background QSOs whose sightlines pass close to foreground QSOs. We detect MgII(2796,2803) absorption in Sloan Digital Sky Survey (SDSS) spectra of four z>1.5 QSOs whose lines of sight pass within 26-98 kpc of lower redshift (z~0.5-1.5) QSOs. The 100% [4/4 pairs] detection of MgII in the background QSOs is clearly at odds with the incidence of associated (z_abs ~ z_em) systems -- absorbers which exist towards only a few percent of QSOs. Although the quality of our foreground QSO spectra is not as high as the SDSS data, absorption seen towards one of the background QSOs clearly does not show up at the same strength in the spectrum of the corresponding foreground QSO. This implies that the absorbing gas is distributed inhomogeneously around the QSO, presumably as a direct consequence of the anisotropic emission from the central AGN. We discuss possible origins for the MgII lines, including: absorption by gas from the foreground QSO h...

  5. Bent Electro-Absorption Modulator

    DEFF Research Database (Denmark)

    2002-01-01

    components and the applied electric field in relation to the frequency of the modulated radiation, the bending losses (and possibly coupling losses) will provide extinction of light guided by the bent waveguide section. The refractive index contract may be modulated while keeping the absorption coefficient...... by bendng losses co-operates to provide more compact modulators with improved performance (extinction) and speed....

  6. Active Absorption Wave Maker System for Irregular Waves

    Institute of Scientific and Technical Information of China (English)

    柳淑学; 王先涛; 李木国; 郭美谊

    2003-01-01

    The key problem in physical model tests with highly reflective structures is to prevent the multiple reflections between the reflective structures and the wave maker. An active absorption wave maker system is described and the representative frequency method for irregular waves is proposed in this paper. Physical model tests are conducted to verify the effectiveness of the proposed method.

  7. Powerful laser pulse absorption in partly homogenized foam plasma

    International Nuclear Information System (INIS)

    The internal volume structure of a porous medium of light elements determines unique features of the absorption mechanism of laser radiation; the characteristics of relaxation and transport processes in the produced plasma are affected as well. Porous materials with an average density larger than the critical density have a central role in enhancing the pressure produced during the ablation by the laser pulse; this pressure can exceed the one produced by target direct irradiation. The problem of the absorption of powerful laser radiation in a porous material is examined both analytically and numerically. The behavior of the medium during the process of pore filling in the heated region is described by a model of viscous homogenization. An expression describing the time and space dependence of the absorption coefficient of laser radiation is therefore obtained from the model. A numerical investigation of the absorption of a nanosecond laser pulse is performed within the present model. In the context of numerical calculations, porous media with an average density larger than the critical density of the laser-produced plasma are considered. Preliminary results about the inclusion of the developed absorption model into an hydrodynamic code are presented

  8. An Unsteady Heterogeneous Mass Transfer Model for Gas Absorption Enhanced by Dispersed Third Phase Droplets%第三分散相液滴增强气体吸收的一维非稳态非均相传质模型

    Institute of Scientific and Technical Information of China (English)

    沈树华; 马友光; 卢素敏; 朱春英

    2009-01-01

    A model for one-dimensional unsteady heterogeneous mass transfer was developed based on Danck-werts' surface renewal theory in order to describe the mass transfer enhancement of absorption process for a slightly soluble gas in a gas-liquid-liquid system. The model accounts for the mass transfer resistance within the dispersed phase and the effect of emulsion viscosity on mass transfer. An analytical solution for enhancement factor was ob-tained by Laplace domain transformation. The absorption rates of carbon dioxide in the dodecane-in-water and cas-tor oil-in-water systems were measured in a thermostatic reactor, and the enhancement factors were calculated at different volume fractions of dispersed phase and stirrer speeds. The model predictions agree well with the experi-mental data.

  9. Inferring surface solar absorption from broadband satellite measurements

    Science.gov (United States)

    Cess, Robert D.; Vulis, Inna L.

    1989-01-01

    An atmospheric solar radiation model and surface albedo models that include wavelength dependence and surface anisotropy are combined to study the possibility of inferring the surface solar absorption from satellite measurements. The model includes ocean, desert, pasture land, savannah, and bog surface categories. Problems associated with converting narrowband measurements to broadband quantities are discussed, suggesting that it would be easier to infer surface solar absorption from broadband measurements directly. The practice of adopting a linear relationship between planetary and surface albedo to estimate surface albedos from satellite measurements is examined, showing that the linear conversion between broadband planetary and surface albedos is strongly dependent on vegetation type. It is suggested that there is a linear slope-offset relationship between surface and surface-atmosphere solar absorption.

  10. Thermodynamic modeling of poorly complexing metals in concentrated electrolyte solutions: an X-ray absorption and UV-Vis spectroscopic study of Ni(II) in the NiCl2-MgCl2-H2O system.

    Science.gov (United States)

    Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

    2015-01-01

    Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at RNi-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg(-1) NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg(-1) NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

  11. Thermodynamic modeling of poorly complexing metals in concentrated electrolyte solutions: an X-ray absorption and UV-Vis spectroscopic study of Ni(II in the NiCl2-MgCl2-H2O system.

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    Full Text Available Knowledge of the structure and speciation of aqueous Ni(II-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration occurs. Both methods confirm that the Ni(II aqua ion (with six coordinated water molecules at RNi-O = 2.07(2 Å is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg(-1 NiCl2, which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23 Cl at a Ni-Cl distance of 2.35(2 Å in 5.05 mol∙kg(-1 NiCl2 in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system.

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

    Science.gov (United States)

    Crisp, D.

    1996-01-01

    The atmospheric radiative transfer algorithms used in most global general circulation models underestimate the globally-averaged solar energy absorbed by cloudy atmospheres by up to 25 Wm(sup -2)...Here, a sophisticated atmospheric radiative transfer model was used to provide a more comprehensive description of the physical processes that contribute to the absorption of solar radiation by the Earth's atmosphere.

  13. Absorption of solar radiation in broken clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B. [Institute of Atmospheric Optics, Tomsk (Russian Federation)

    1996-04-01

    It is recognized now that the plane-parallel model unsatisfactorily describes the transfer of radiation through broken clouds and that, consequently, the radiation codes of general circulation models (GCMs) must be refined. However, before any refinement in a GCM code is made, it is necessary to investigate the dependence of radiative characteristics on the effects caused by the random geometry of cloud fields. Such studies for mean fluxes of downwelling and upwelling solar radiation in the visible and near-infrared (IR) spectral range were performed by Zuev et al. In this work, we investigate the mean spectral and integrated absorption of solar radiation by broken clouds (in what follows, the term {open_quotes}mean{close_quotes} will be implied but not used, for convenience). To evaluate the potential effect of stochastic geometry, we will compare the absorption by cumulus (0.5 {le} {gamma} {le} 2) to that by equivalent stratus ({gamma} <<1) clouds; here {gamma} = H/D, H is the cloud layer thickness and D the characteristic horizontal cloud size. The equivalent stratus clouds differ from cumulus only in the aspect ratio {gamma}, all the other parameters coinciding.

  14. Chromophore design for large two-photon absorption

    Science.gov (United States)

    Dudley, Christopher

    2014-11-01

    Conjugated oligothiophene chromophores are compared and studied for designing large linear and nonlinear absorption cross-sections. Optical properties of chromophores synthesized by the Naval Research Laboratory are modeled to construct a design factor of merit to predict and understand two-photon absorption (TPA) designs. Computer modeling to optimize parameters to produce photo active chromophores is conducted. Geometry, π-center (electron relay) and the electron donor or acceptor groups attached to the π-centers are considered for importance in TPA. This work could serve equally well as guide for quick back of the envelop research or industrial design verifications as well as an outline for introducing computation methods to students.

  15. Analysis of Decentralized Control for Absorption Cycle Heat Pumps

    DEFF Research Database (Denmark)

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard;

    2015-01-01

    Email Print Request Permissions This paper investigates decentralized control structures for absorption cycle heat pumps and a dynamic nonlinear model of a single-effect LiBr-water absorption system is used as case study. The model has four controllable inputs, which can be used to stabilize the ...... to minimize the effect of cross couplings and improve stability with the right pairing of input and output. Simulation of selected candidate input-output pairings demonstrate that decentralized control can provide stable operation of the heat pump....

  16. The distribution of absorptive power dissipation in irradiated nanoparticulate system

    Science.gov (United States)

    Li, Jiayu; Yang, Jian; Gu, Xiaobing

    2016-10-01

    The knowledge of local radiant absorption is important to the nanostructure optimization, it is beneficial to the applications in energy harvesting, optical heating, photocatalysis, etc. In this paper, FDTD model is constructed for the distribution of absorptive power dissipation in irradiated nanoparticulate system. The theoretical model extended from Mie theory is used to examine the FDTD model, the parameters and conditions set for FDTD simulation are confirmed based on the comparison. Then, the influence of Ag nanoparticle on the absorptive properties of nearby TiO2 nanoparticle is investigated by FDTD simulation at the wavelength of 0.25 μm. It is indicated that suitable distance between TiO2 and Ag particles is beneficial to the spectral radiant absorption of TiO2 particle. Considering the agglomeration of nanoparticles and the oxidation at the TiO2-Ag interface, the Ag core coated with Al2O3 shell is suggested, and the simulated results indicated that the shell thickness and the Ag core size need to be optimized for enhancing the radiant absorption of TiO2 particle.

  17. Mechanical Parameters Effects on Acoustic Absorption at Polymer Foam

    Directory of Open Access Journals (Sweden)

    Lyes Dib

    2015-01-01

    Full Text Available Polymer foams have acoustic absorption properties that play an important role in reducing noise level. When the skeleton is set to motion, it is necessary to use generalized Biot-Allard model which takes into account the deformation of the skeleton and the fluid and the interactions between them. The aim of this work is to study the quality of acoustic absorption in polyurethane foam and to show the importance of the structural vibration of this foam on the absorption by varying mechanical parameters (Young’s modulus E, Poisson’s coefficient ν, structural damping factor η, and the density ρ1. We calculated the absorption coefficient analytically using classical Biot formulation (us, uf and numerically using Biot mixed formulation (us, p in 3D COMSOL Multiphysics. The obtained results are compared together and show an excellent agreement. Afterwards, we studied the effect of varying each mechanical parameter independently on the absorption in interval of ±20%. The simulations show that these parameters have an influence on the sound absorption around the resonance frequency fr.

  18. Analysis of crystallization risk in double effect absorption refrigeration systems

    International Nuclear Information System (INIS)

    Absorption refrigeration systems are an alternative to vapor compression ones in cooling and refrigeration applications. In comparison with single effect absorption units, double effect systems have improved performance. Also, they are more available commercially than the other multi effect absorption cycles. An important challenge in the operation of such systems is the possibility of crystallization within them. This is especially true in developing air-cooled absorption systems, which are attractive because cooling tower and associated installation and maintenance issues can be avoided. Therefore, distinguishing the working conditions that may cause crystallization can be useful in the design and control of these systems. In this paper a computational model has been developed to study and compare the effects of operating parameters on crystallization phenomena in three classes of double effect lithium bromide-water absorption refrigeration systems (series, parallel and reverse parallel) with identical refrigeration capacities. It is shown that the range of operating conditions without crystallization risks in the parallel and the reverse parallel configurations is wider than those of the series flow system. - Highlights: → We study crystallization of double effect absorption refrigeration systems. → We consider series, parallel and reverse parallel cycles. → We study the effect of operating conditions on crystallization. → We choose optimum distribution ratio for parallel and reverse parallel systems. → Crystallization possibility is low in parallel and reverse parallel cycles.

  19. Estimation of lunar titanium content: Based on absorption features of Chang’E-1 interference imaging spectrometer (ⅡM)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Two linear regression models based on absorption features extracted from CE-1 IIM image data are presented to discuss the relationship between absorption features and titanium content. We computed five absorption parameters (Full Wave at Half Maximum (FWHM), absorption position, absorption area, absorption depth and absorption asymmetry) of the spectra collected at Apollo 17 landing sites to build two regression models, one with FWHM and the other without FWHM due to the low relation coefficient between FWHM and Ti content. Finally Ti content measured from Apollo 17 samples and Apollo 16 samples was used to test the accuracy. The results show that the predicted values of the model with FWHM have many singular values and the result of model without FWHM is more stable. The two models are relatively accurate for high-Ti districts, while seem inexact and disable for low-Ti districts.

  20. Quasi-static energy absorption of hollow microlattice structures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, YL; Schaedler, TA; Jacobsen, AJ; Chen, X

    2014-12-01

    We present a comprehensive modeling and numerical study focusing on the energy quasi-static crushing behavior and energy absorption characteristics of hollow tube microlattice structures. The peak stress and effective plateau stress of the hollow microlattice structures are deduced for different geometrical parameters which gives volume and mass densities of energy absorption, D-v and D-m, scale with the relative density, (rho) over bar, as D-v similar to (rho) over bar (1) (5) and D-m similar to (rho) over bar (0 5), respectively, fitting very well to the experimental results of both 60 degrees inclined and 90 degrees predominately microlattices. Then the strategies for energy absorption enhancement are proposed for the engineering design of microlattice structures. By introducing a gradient in the thickness or radius of the lattice members, the buckle propagation can be modulated resulting in an increase in energy absorption density that can exceed 40%. Liquid filler is another approach to improve energy absorption by strengthening the microtruss via circumference expansion, and the gain may be over 100% in terms of volume density. Insight into the correlations between microlattice architecture and energy absorption performance combined with the high degree of architecture control paves the way for designing high performance microlattice structures for a range of impact and impulse mitigation applications for vehicles and structures. (C) 2014 Elsevier Ltd. All rights reserved.

  1. Theory of graphene saturable absorption

    CERN Document Server

    Marini, A; de Abajo, F J Garcia

    2016-01-01

    Saturable absorption is a non-perturbative nonlinear optical phenomenon that plays a pivotal role in the generation of ultrafast light pulses. Here we show that this effect emerges in graphene at unprecedentedly low light intensities, thus opening avenues to new nonlinear physics and applications in optical technology. Specifically, we theoretically investigate saturable absorption in extended graphene by developing a non-perturbative single-particle approach, describing conduction-electron dynamics in the atomically-thin material using the two-dimensional Dirac equation for massless Dirac fermions, which is recast in the form of generalized Bloch equations. By solving the electron dynamics non-perturbatively, we account for both interband and intraband contributions to the intensity-dependent saturated conductivity and conclude that the former dominates regardless of the intrinsic doping state of the material. The results are in excellent agreement with atomistic quantum-mechanical simulations including high...

  2. The intestinal absorption of folates.

    Science.gov (United States)

    Visentin, Michele; Diop-Bove, Ndeye; Zhao, Rongbao; Goldman, I David

    2014-01-01

    The properties of intestinal folate absorption were documented decades ago. However, it was only recently that the proton-coupled folate transporter (PCFT) was identified and its critical role in folate transport across the apical brush-border membrane of the proximal small intestine established by the loss-of-function mutations identified in the PCFT gene in subjects with hereditary folate malabsorption and, more recently, by the Pcft-null mouse. This article reviews the current understanding of the properties of PCFT-mediated transport and how they differ from those of the reduced folate carrier. Other processes that contribute to the transport of folates across the enterocyte, along with the contribution of the enterohepatic circulation, are considered. Important unresolved issues are addressed, including the mechanism of intestinal folate absorption in the absence of PCFT and regulation of PCFT gene expression. The impact of a variety of ions, organic molecules, and drugs on PCFT-mediated folate transport is described. PMID:24512081

  3. Effect of Nitrogen Application Models on the Dynamic of Nutrient Absorption of Spring Maize%施氮模式对春玉米养分吸收动态的影响

    Institute of Scientific and Technical Information of China (English)

    隽英华; 汪仁; 孙文涛; 邢月华; 宫亮; 蔡广兴

    2011-01-01

    By the test in spring maize field and laboratory analysis, the dynamic behavior of nutrient absorption of spring maize and the fertilizer N use efficiency were studied as affected by models of nitrogen application. The results showed that nitrogen application enhanced N, P and K contents of maize plant, and improved the maize yield character. With growth stages, the N and K contents of each organ of maize plant decreased, and P content changed with no rule. Compared with other models of nitrogen application, two topdressings and one deep application both showed greater preponderance, whose output-input ratio, N agronomic efficiency and fertilizer N use efficiency were 7.78, 29.05 kg/kg and 40.13% and 6.93, 24.38 kg/kg and 39.92%, respectively. Considered fertilizer requirement characteristics of maize and fertilizer properties, it was filtrated that, P and K fertilizers as basic fertilizer, and N fertilizer as basic fertilizer, jointing fertilizer and big trumpet fertilizer and as basic fertilizer with one deep application were the best techniques of fertilizer application.%通过春玉米田间试验和室内分析,研究施氮模式对春玉米养分吸收动态及氮肥利用率的影响.结果表明,施氮提高了玉米植株氮、磷、钾含量,改善了玉米产量性状.随着生育期推进,玉米植株各器官氮、钾含量逐渐降低,磷含量变化无规律性.与其他施氮模式相比,二次追肥和一次深施处理显示出较大的优势,其中,产投比分别为7.78和6.93,氮肥农学效率分别为29.05 kg/kg和24.38 kg/kg,氮肥利用率分别为40.13%和39.92%.结合玉米的生理需肥特性和肥料性质,磷、钾肥作基肥,氮肥作基肥+拔节肥追肥+大喇叭口肥追肥和氮肥一次深施为适宜的施肥技术.

  4. Photodetector with enhanced light absorption

    Science.gov (United States)

    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.

  5. Chaos and multiple photon absorption

    International Nuclear Information System (INIS)

    An anharmonic vibrational mode of a molecule, driven by an intense infrared laser and coupled to a quasi-continuum of background modes, is found to undergo chaotic oscillations. This chaos leads to predominantly fluence-dependent rather than intensity-dependent multiple-photon absorption, as is found experimentally. The loss of coherence is associated with the decay of temporal correlation of background-mode oscillations

  6. Maximum-likelihood absorption tomography

    International Nuclear Information System (INIS)

    Maximum-likelihood methods are applied to the problem of absorption tomography. The reconstruction is done with the help of an iterative algorithm. We show how the statistics of the illuminating beam can be incorporated into the reconstruction. The proposed reconstruction method can be considered as a useful alternative in the extreme cases where the standard ill-posed direct-inversion methods fail. (authors)

  7. Examination of oral absorption and lymphatic transport of halofantrine in a triple-cannulated canine model after administration in self-microemulsifying drug delivery systems (SMEDDS) containing structured triglycerides

    DEFF Research Database (Denmark)

    Holm, René; Porter, Christopher J H; Edwards, Glenn A;

    2003-01-01

    availability was affected by the triglyceride incorporated into the multi-component delivery system and availabilities of 56.9% (MLM) and 37.2% (LML) were found. These data indicate that the pharmaceutical scientist can use the structure of the lipid to affect the relative contribution of the two absorption...... pathways. The MLM formulation produced a total bioavailability of 74.9%, which is higher than the total absorption previously observed after post-prandial administration. This could indicate the utility of disperse lipid-base formulations based on structured triglycerides for the oral delivery...

  8. Theory of strong-field attosecond transient absorption

    Science.gov (United States)

    Wu, Mengxi; Chen, Shaohao; Camp, Seth; Schafer, Kenneth J.; Gaarde, Mette B.

    2016-03-01

    Attosecond transient absorption is one of the promising new techniques being developed to exploit the availability of sub-femtosecond extreme ultraviolet (XUV) pulses to study the dynamics of the electron on its natural time scale. The temporal resolution in a transient absorption setup comes from the control of the relative delay and coherence between pump and probe pulses, while the spectral resolution comes from the characteristic width of the features that are being probed. In this review we focus on transient absorption scenarios where an attosecond pulse of XUV radiation creates a broadband excitation that is subsequently probed by a few cycle infrared (IR) laser. Because the attosecond XUV pulses are locked to the IR field cycle, the exchange of energy in the laser-matter interaction can be studied with unprecedented precision. We focus on the transient absorption by helium atoms of XUV radiation around the first ionization threshold, where we can simultaneoulsy solve the time-dependent Schrödinger equation for the single atom response and the Maxwell wave equation for the collective response of the nonlinear medium. We use a time-domain method that allows us to treat on an equal footing all the different linear and nonlinear processes by which the medium can exchange energy with the fields. We present several simple models, based on a few-level system interacting with a strong IR field, to explain many of the novel features found in attosecond transient absorption spectrograms. These include the presence of light-induced states, which demonstrate the ability to probe the dressed states of the atom. We also present a time-domain interpretation of the resonant pulse propagation features that appear in absorption spectra in dense, macroscopic media. We close by reviewing several recent experimental results that can be explained in terms of the models we discuss. Our aim is to present a road map for understanding future attosecond transient absorption

  9. Evolution of absorption machines; Evolution des machines a absorption

    Energy Technology Data Exchange (ETDEWEB)

    Soide, I.; Klemsdal, E. [Gaz de France (GDF), 75 - Paris (France); Le Goff, P.; Hornut, J.M. [LSGC-ENSIC, 54 - Nancy (France)

    1997-12-31

    Most of todays absorption air-conditioning machineries use the lithium bromide-water pair. The most performing can operate at a 150-160 deg. C, the temperature being limited by the corrosion resistance of metals with respect to LiBr solutions. Also, there is a revival of interest for water-ammonia systems. These systems require the use of a rectification column which reduces the coefficient of performance. Higher thermal performances are reached with hydrocarbon pairs and ternary mixtures (water-methanol-LiBr etc..). This paper presents different schemes of refrigerating heat pumps based on these different systems. (J.S.)

  10. Resonant Optical Absorption in Semiconductor Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    YU Li-Yuan; CAO Jun-Cheng

    2004-01-01

    @@ We have calculated the intraband photon absorption coefficients of hot two-dimensional electrons interacting with polar-optical phonon modes in quantum wells. The dependence of the photon absorption coefficients on the photon wavelength λ is obtained both by using the quantum mechanical theory and by the balance-equation theory. It is found that the photon absorption spectrum displays a local resonant maximum, corresponding to LO energy, and the absorption peak vanishes with increasing the electronic temperature.

  11. Structural sound absorption in liquid metals

    International Nuclear Information System (INIS)

    Present article is devoted to structural sound absorption in liquid metals. The study of sound absorption in liquid metals shown that in all studied objects the structural absorption of sound was observed. The mechanism of structural relaxation in molten metal was revealed.

  12. Lactulose stimulates calcium absorption in postmenopausal women

    NARCIS (Netherlands)

    Heuvel, E.G.H.M. van den; Muijs, T.; Dokkum, W. van; Schaafsma, G.

    1999-01-01

    Animal studies have indicated that calcium absorption is increased by lactulose, a synthetic disaccharide. Therefore, the influence of lactulose on calcium absorption was measured in postmenopausal women who may benefit from the possible enhancing effect of lactulose on calcium absorption. Twelve po

  13. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus

    Directory of Open Access Journals (Sweden)

    Shuai Li

    2016-06-01

    Full Text Available The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A1; the findings indicated that the bioavailability of Holotoxin A1 was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A1, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor. The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A1, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins.

  14. Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus.

    Science.gov (United States)

    Li, Shuai; Wang, Yuanhong; Jiang, Tingfu; Wang, Han; Yang, Shuang; Lv, Zhihua

    2016-01-01

    The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A₁; the findings indicated that the bioavailability of Holotoxin A₁ was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A₁, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A₁, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins. PMID:27322290

  15. Water Vapor Absorption in Early M-type Stars

    CERN Document Server

    Matsuura, M; Murakami, H; Freund, M M; Tanaka, M

    1999-01-01

    The spectrometers onboard the Infrared Telescope in Space (IRTS) reveal water vapor absorption in early M-type stars, as early as M2. Previous observations detected H_2O vapor absorption only in stars later than M6, with the exception of the recent detection of H_2O in beta Peg (M2.5 II-III). In our sample of 108 stars, 67 stars have spectral types earlier than M6. The spectral types are established by means of their near-infrared colors on a statistical basis. Among the 67 stars of spectral types earlier than M6, we find water vapor absorption in six stars. The observed absorption features are interpreted using a local thermodynamic equilibrium model. The features are reasonably fitted by model spectra with excitation temperatures of 1000-1500 K and water column densities of 5x10^19 to 1x10^20 cm^-2. These numbers imply that the H_2O molecules are present in a region of the atmosphere, located above the photosphere. Furthermore, our analysis shows a good correlation between the H_2O absorption band strength,...

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

    Science.gov (United States)

    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.

  17. 44th Annual Anomalous Absorption Conference

    Energy Technology Data Exchange (ETDEWEB)

    Beg, Farhat

    2014-03-03

    Conference Grant Report July 14, 2015 Submitted to the U. S. Department of Energy Attn: Dr. Sean Finnegan By the University of California, San Diego 9500 Gilman Drive La Jolla, California 92093 On behalf of the 44th Annual Anomalous Absorption Conference 8-13 June 2014, in Estes Park, Colorado Support Requested: $10,100 Amount expended: $3,216.14 Performance Period: 1 March 20 14 to 28 February 20 15 Principal Investigator Dr. Farhat Beg Center for Energy Research University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0417 858-822-1266 (telephone) 858-534-4543 (fax) fbeg@ucsd.edu Administrative Point of Contact: Brandi Pate, 858-534-0851, blpate®ucsd.edu I. Background The forty-fourth Anomalous Absorption Conference was held in Estes Park, Colorado from June 5-8, 2014 (aac2014.ucsd.edu). The first Anomalous Absorption Conference was held in 1971 to assemble experts in the poorly understood area of laser-plasma absorption. The goal of that conference was to address the anomalously large laser absorption seen in plasma experiments with respect to the laser absorption predicted by linear plasma theory. Great progress in this research area has been made in the decades since that first meeting, due in part to the scientific interactions that have occurred annually at this conference. Specifically, this includes the development of nonlinear laser-plasma theory and the simulation of laser interactions with plasmas. Each summer since that first meeting, this week-long conference has been held at unique locations in North America as a scientific forum for intense scientific exchanges relevant to the interaction of laser radiation with plasmas. Responsibility for organizing the conference has traditional rotated each year between the major Inertial Confinement Fusion (ICF) laboratories and universities including LANL, LLNL, LLE, UCLA UC Davis and NRL. As the conference has matured over the past four decades, its technical footprint has expanded

  18. The risk of hydroquinone and sunscreen over-absorption via photodamaged skin is not greater in senescent skin as compared to young skin: nude mouse as an animal model.

    Science.gov (United States)

    Hung, Chi-Feng; Chen, Wei-Yu; Aljuffali, Ibrahim A; Shih, Hui-Chi; Fang, Jia-You

    2014-08-25

    Intrinsic aging and photoaging modify skin structure and components, which subsequently change percutaneous absorption of topically applied permeants. The purpose of this study was to systematically evaluate drug/sunscreen permeation via young and senescent skin irradiated by ultraviolet (UV) light. Both young and senescent nude mice were subjected to UVA (10 J/cm(2)) and/or UVB radiation (175 mJ/cm(2)). Physiological parameters, immunohistology, and immunoblotting were employed to examine the aged skin. Hydroquinone and sunscreen permeation was determined by in vitro Franz cell. In vivo skin absorption was documented using a hydrophilic dye, rhodamine 123 (log P=-0.4), as a permeant. UVA exposure induced cyclooxygenase (COX)-2 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) upregulation. Epidermal tight junction (TJ) were degraded by UVA. UVB increased transepidermal water loss (TEWL) from 13 to 24 g/m(2)/h. Hyperplasia and inflammation, but not loss of TJ, were also observed in UVB-treated skin. UVA+UVB- and UVA-irradiated skin demonstrated similar changes in histology and biomarkers. UVA+UVB or UVA exposure increased hydroquinone flux five-fold. A negligible alteration of hydroquinone permeation was shown with UVB exposure. Hydroquinone exhibited a lower penetration through senescent skin than young skin. Both UVA and UVB produced enhancement of oxybenzone flux and skin uptake. However, the amount of increase was less than that of hydroquinone delivery. Photoaging did not augment skin absorption of sunscreens with higher lipophilicity, including avobenzone and ZnO. Exposure to UVA generally increased follicular entrance of these permeants, which showed two- to three-fold greater follicular uptake compared to the untreated group. Photoaging had less impact on drug/sunscreen absorption with more lipophilic permeants. Percutaneous absorption did not increase in skin subjected to both intrinsic and extrinsic aging. PMID:24858384

  19. Compression-absorption cascade refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Sieres, Jaime; Vazquez, Manuel [Area de Maquinas y Motores Termicos, Escuela Tecnica Superior de Ingenieros Industriales, Universidade de Vigo, Campus Lagoas-Marcosende, 9, 36200 Vigo (Spain)

    2006-04-01

    This paper describes the study carried out to analyse a refrigeration system in cascade with a compression system at the low temperature stage and an absorption system at the high temperature stage to generate cooling at low temperatures, as well as the possibility of powering it by means of a cogeneration system. CO{sub 2} and NH{sub 3} have been considered as refrigerants in the compression stage and the pair NH{sub 3}-H{sub 2}O in the absorption stage. The analysis has been realized by means of a mathematical model of the refrigeration system implemented in a computer program and taking into account the characteristic operating conditions of a cogeneration system with gas engines. The paper presents the results obtained regarding the performance of the refrigeration system and the adaptability between the power requirements of the refrigeration system and the power supplied by the cogeneration system taking into account the present Spanish Regulations about the use of cogeneration systems. [Author].

  20. AGN Absorption Linked to Host Galaxies

    CERN Document Server

    Juneau, Stéphanie

    2013-01-01

    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. These proceedi...

  1. Percutaneous absorption of methimazole: an in vitro study of the absorption pharmacokinetics for two different vehicles.

    Science.gov (United States)

    Hill, K E; Mills, P C; Jones, B R; Bolwell, C F; Aberdein, D; Chambers, J P

    2015-12-01

    The use of transdermal medications in cats has become popular in veterinary medicine due to the ease of administration compared to oral medication. However, the research to support systemic absorption of drugs applied to the pinna after transdermal administration in cats is limited. The aim of this study was to characterize the percutaneous absorption pharmacokinetics of methimazole in a lipophilic vehicle compared to methimazole in Pluronic(®) lecithin organogel (PLO) using a finite dose applied to feline ear skin in an in vitro Franz cell model. The two formulations of methimazole (10 mg) were applied to the inner stratum corneum of six pairs of feline ears. The receptor medium was sampled up to 30 h post-administration, and methimazole concentrations were measured using high-performance liquid chromatography (HPLC). Histological examination of all ears was undertaken as small differences in the thickness of ear skin may have contributed to inter-individual differences in methimazole absorption between six cats. Methimazole was absorbed more completely across the pinnal skin when administered in the lipophilic vehicle compared to administration in the PLO gel (P < 0.001).

  2. Absorption effects in intermediate-energy electron scattering by difluoroethylene

    International Nuclear Information System (INIS)

    Full text: Although several solid-based ab-initio theoretical methods have been developed in the past few decades for the investigation on electron-molecule collisions, most of them can only be successfully applied in the low incident electron energy range. The extension of their application to the intermediate-energy range (roughly from the first ionization potential to around 1 keV) is not straightforward. It is known that at these energies the numerous open inelastic scattering channels are responsible for absorption effects that play an important role on the collision dynamics. In the last two decades, several model absorption potentials have been proposed to include absorption effects into the scattering dynamics and so, the resolution of the scattering equations is kept in the single-channel framework. Although these model-potential methods have shown to provide, in general, quite accurate differential (DCS), integral (ICS) and momentum-transfer (MTCS) cross sections for elastic electron-molecule collisions, most of the calculations have systematically underestimated the values of the grand-total (TCS) and total absorption (TACS) cross sections. In recent papers, our group has reported a modified version of the widely used Stazewska's version 3 of the quasi-free scattering model (QFSM3) absorption potential. In order to obtain a better description of screening effects due to the target electronic cloud, we have proposed a multiplicative screening factor that should be applied on the original QFSM3 absorption potential. In our works, we have shown that such a simple modification in the absorption model potential is capable of providing significant improvement in the calculated TCS and TAGS for a variety of targets for intermediate-energy electron-molecule collisions. In the present work we apply our modified model absorption potential to study electron scattering by a strongly polar molecule, cis-difluoroethylene in a wide incident energy range (1-500 e

  3. Determination of absorption coefficients in AlInP lattice matched to GaAs

    Science.gov (United States)

    Cheong, J. S.; Ng, J. S.; Krysa, A. B.; Ong, J. S. L.; David, J. P. R.

    2015-10-01

    The absorption properties of Al0.52In0.48P have been investigated near the fundamental absorption edge by measuring the photocurrent as a function of wavelength in a series of PIN and NIP diodes. Modelling of the photocurrent in these structures enables the absorption coefficients to be determined accurately over a wide dynamic range, which allows the direct and indirect band-gap to be determined.

  4. Research program in nuclear and solid state physics. [including pion absorption spectra and muon spin precession

    Science.gov (United States)

    1974-01-01

    The survey of negative pion absorption reactions on light and medium nuclei was continued. Muon spin precession was studied using an iron target. An impulse approximation model of the pion absorption process implied that the ion will absorb almost exclusively on nucleon pairs, single nucleon absorption being suppressed by energy and momentum conservation requirements. For measurements on both paramagnetic and ferromagnetic iron, the external magnetic field was supplied by a large C-type electromagnet carrying a current of about 100 amperes.

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

    OpenAIRE

    Müller, T. (Tessa); Virkkula, A.; Ogren, J.A.

    2014-01-01

    We present a new correction scheme for filter-based absorption photometers based on a constrained two-stream (CTS) radiative transfer model and experimental calibrations. The two-stream model was initialized using experimentally accessible optical parameters of the filter. Experimental calibrations were taken from the literature and from dedicated experiments for the present manuscript. Uncertainties in the model and calibration experiments are discussed and uncertainties fo...

  6. Carbon Dioxide Absorption Heat Pump

    Science.gov (United States)

    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.

  7. Phytases for Improved Iron Absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Nyffenegger, Christian; Meyer, Anne S.

    2014-01-01

    Microbial phytases (EC 3.1.3.8) catalyse dephosphorylation of phytic acid, which is the primary storage compound for phosphorous in cereal kernels. The negatively charged phosphates in phytic acid chelate iron (Fe3+) and thus retards iron bioavailability in humans 1. Supplementation of microbial...... phytase can improve iron absorption from cereal-based diets 2. In order for phytase to catalyse iron release in vivo the phytase must be robust to low pH and proteolysis in the gastric ventricle. Our work has compared the robustness of five different microbial phytases, evaluating thermal stability...

  8. Water dimer absorption of visible light

    OpenAIRE

    Hargrove, J

    2007-01-01

    International audience Laboratory measurements of water vapor absorption using cavity ring-down spectroscopy revealed a broad absorption at 405 nm with a quadratic dependence on water monomer concentration, a similar absorption with a linear component at 532 nm, and only linear absorption at 570 nm in the vicinity of water monomer peaks. D2O absorption is weaker and linear at 405 nm. Van't Hoff plots constructed at 405.26 nm suggest that for dimerization, Keq=0.056±0.02 atm?1, ?H°301 K=?16...

  9. The Mechanism of Interfacial Mass Transfer in Gas Absorption Process

    Institute of Scientific and Technical Information of China (English)

    马友光; 冯惠生; 徐世昌; 余国琮

    2003-01-01

    Based on the method of molecular thermodynamics ,the mass transfer mechanism at gas-liquid interface is studied theoretically,and a nowe mathematical model is proposed,Using laser holographic interference technique,the hydrodynamics and mass transfer characteristics of CO2 absorption are measured,It is shown that the calculated results are in good agreement with the experimental data.

  10. Light-Induced Absorption in Nominally Pure Bismuth Silicon Oxide

    Institute of Scientific and Technical Information of China (English)

    李飞飞; 许京军; 孔勇发; 黄辉; 张光寅; 杨春晖; 徐玉恒

    2001-01-01

    Light-induced absorption in the nominally pure bismuth silicon oxide is investigated experimentally and the result shows that it consists of transient and persistent parts. The experimental evidence is analysed based on the model of three groups of trap (donor) centres.

  11. Lifshitz Tails for the Interband Light Absorption Coefficient

    Indian Academy of Sciences (India)

    W Kirsch; M Krishna

    2010-09-01

    In this paper we consider the interband light absorption coefficient (ILAC) for various models. We show that at the lower and upper edges of the spectrum the Lifshitz tails behaviour of the density of states implies similar behaviour for the ILAC at appropriate energies. The Lifshitz tails property is also exhibited at some points corresponding to the internal band edges of the spectrum.

  12. Effects of flavour absorption on foods and their packaging materials

    NARCIS (Netherlands)

    Willige, van R.W.G.

    2002-01-01

    Keywords: flavour absorption, scalping, packaging, food matrix, lldpe, ldpe, pp, pc, pet, pen,b-lactoglobulin, casein, pectin, cmc, lactose, saccharose, oil, modelling, storage, oxygen permeability, taste perception, sensory quality.Abso

  13. Optical absorption and scattering properties in the East China Sea

    Science.gov (United States)

    Zhang, Xuan; He, Xian-qiang; Chen, Xiao-yan; Hao, Zeng-zhou; Huang, Haiqing; Zhu, Qiankun

    2011-11-01

    The absorption and particulate backscattering coefficients are the basic parameters of the water inherent optical properties (IOPs), which are also the basic parameters for the development and validation of the semi-analysis models of the ocean color remote sensing. In this work, the absorption and backscattering coefficients in the East China Sea (ECS) were measured in the summer and winter of 2009 using the three in-situ optical instruments, including the WET Labs acs, and the HOBI Labs HydroScat-6. Based on the in-situ measured data, the distribution of the absorption and backscattering coefficients in the ECS are analyzed. The results show that in the summer the water absorption coefficient at 440nm (a(440nm),excluding the absorption of the pure sea water) in the surface layer is ranged from 0.022 to 0.067 m-1, and the particulate backscattering coefficient at 442nm(bbp(442nm), is between 0.00064 and 0.03274 m-1. As a whole, both of the absorption and backscattering coefficients decrease with the offshore direction, and the high values located at the mouth of Changjiang River. In the winter, a(440nm) is between 0.051 and 0.887 m-1, and bbp(442nm) is ranged from 0.000639 to 0.14614 m-1 at the surface layer. The spatial distributions in winter are similar as the summer, with the high value in the coast and low value in the offshore. The absorption and backscattering coefficients in winter are significantly larger than the summer's, especially in coastal area near the mouth of Changjiang River, which maybe caused by the southward Fujian-Zhejiang coastal current occurring in winter. As the vertical profile distributions, we find that both of the absorption and backscattering coefficients present a layer structure, which caused by the stratification of the sea water in the summer; while in the winter, affected by the strong wind disturbing, both of the absorption and backscattering coefficients are thoroughly vertical mixing. To our knowledge, it is the first time

  14. Absorption and emission properties of photonic crystals and metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Lili [Iowa State Univ., Ames, IA (United States)

    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.

  15. Microwave absorption by nanoresonator vibrations tuned with surface modification

    Science.gov (United States)

    Krivosudský, Ondrej; Cifra, Michal

    2016-08-01

    Elucidating the physical and chemical parameters that govern viscous damping of nanoresonator vibrations and their coupling to electromagnetic radiation is important for understanding the behavior of matter at the nanoscale. Here we develop an analytical model of microwave absorption of a longitudinally oscillating and electrically polar rod-like nanoresonator embedded in a viscoelastic fluid. We show that the slip length, which can be tuned via surface modifications, controls the quality factor and coupling of nanoresonator vibration modes to microwave radiation. We demonstrate that the larger slip length brings the sharper frequency response of the nanoresonator vibration and electromagnetic absorption. Our findings contribute to design guidelines of fluid embedded nanoresonator devices.

  16. Absorption and Ablation for Non-Planar Geometries

    Science.gov (United States)

    Oh, Benjamin; Sinko, John

    2011-04-01

    The Bouguer-Lambert-Beer absorption law is a critical component of analytical laser ablation models. This law has been found to be useful for planar applications but it can also have significance in non-planar geometries. To be accurate, these applications must take into consideration the precise physical setup. Certain geometries offer special properties that may be beneficial to laser propulsion methods, specifically those of uniform ablation using focusing nozzles. This paper investigates the special circumstances using modified forms of the absorption law that apply to the considered parabolic, conical and spherical non-planar geometries.

  17. Iron Absorption in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Fanis Missirlis

    2013-05-01

    Full Text Available 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.

  18. Iron Absorption in Drosophila melanogaster

    Science.gov (United States)

    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. Ozone absorption in a mechanically stirred reactor

    Directory of Open Access Journals (Sweden)

    LJILJANA TAKIC

    2007-08-01

    Full Text Available Ozone absorption in water was investigated in a mechanically stirred reactor, using both the semi-batch and continuous mode of operation. A model for the precise determination of the volumetric mass transfer coefficient in open tanks without the necessity of the measurement the ozone concentration in the outlet gas was developed. It was found that slow ozone reactions in the liquid phase, including the decomposition of ozone, can be regarded as one pseudo-first order reaction. Under the examined operating conditions, the liquid phase was completely mixed, while mixing in a gas phase can be described as plug flow. The volumetric mass transfer coefficient was found to vary with the square of the impeller speed.

  20. Modelación de la transferencia de calor y masa en el absorbedor de una máquina de refrigeración por absorción. // Heat and mass transference modeling in the absorvetor of an absorption cooling device.

    Directory of Open Access Journals (Sweden)

    C. Cisneros Ramírez

    2003-01-01

    Full Text Available En este artículo se dan las expresiones que caracterizan el comportamiento de la temperatura y del producto coeficienteglobal de traspaso de calor (U por el área de traspaso de calor (A , de un absorbedor de una máquina de refrigeración porabsorción que trabaja con la solución amoniaco – agua.Palabras claves: Modelación, absorbedores, refrigeración por absorción.______________________________________________________________________________Abstract.In this article the expressions that characterize the temperature performance and the global heat exchange (U by the heatexchange area (A of the absorvetor of an absorption refrigerating equipment with aqua–ammonia solution are given.Key words: Model, absorber, absorption refrigeration.

  1. Methane absorption variations in the spectrum of Pluto

    International Nuclear Information System (INIS)

    The lightcurve phases of 0.18, 0.35, 0.49, and 0.98 covered by 5600-10,500 A absolute spectrophotometry of Pluto during four nights include minimum (0.98) light and one near-maximum (0.49) light. The spectra are noted to exhibit significant methane band absorption depth variations at 6200, 7200, 7900, 8400, 8600, 8900, and 10,000 A, with the minimum absorption occurring at minimum light and thereby indicating a 30-percent change in the methane column abundance in the course of three days. An attempt is made to model this absorption strength variation with rotational phase terms of an isotropic surface distribution of methane frost and a clear layer of CH4 gas. 34 references

  2. Microwave absorption properties of Ni/(C, silicides) nanocapsules

    Science.gov (United States)

    Jiang, Jingjing; Wang, Han; Guo, Huaihong; Yang, Teng; Tang, Wen-Shu; Li, Da; Ma, Song; Geng, Dianyu; Liu, Wei; Zhang, Zhidong

    2012-05-01

    The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the `core/shell' interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon.

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

    Science.gov (United States)

    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 water, propylene glycol, and polyethylene glycol 400, that a relationship between permeant absorption and the rate of solvent evaporation was observed. PMID:25261711

  4. Absorption of water and lubricating oils into porous nylon

    Science.gov (United States)

    Bertrand, P. A.

    1995-01-01

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

  5. Dynamic energy absorption characteristics of hollow microlattice structures

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Absorber performance of a water/lithium-bromide absorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Xie Guozhen [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China)], E-mail: xieguozhen@bucea.edu.cn; Sheng Guogang [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China); Bansal, Pradeep Kumar [Department of Mechanical Engineering, The University of Auckland, Private Bag 92019 (New Zealand); Li, Guang [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China)

    2008-09-15

    An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure.

  7. Absorber performance of a water/lithium-bromide absorption chiller

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Guozhen; Sheng, Guogang; Li, Guang [Beijing University of Civil Engineering and Architecture, Beijing 100044 (China); Bansal, Pradeep Kumar [Department of Mechanical Engineering, The University of Auckland, Private Bag 92019 (New Zealand)

    2008-09-15

    An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Arpana, E-mail: agrawal.arpana01@gmail.com; Dar, Tanveer A.; Solanki, Ravi; Sen, Pratima [Laser Bhawan, School of Physics, Devi Ahilya University, Khandwa Road, Indore-452001 (India); Phase, D. M. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India)

    2015-06-24

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

  10. Two-photon-assisted excited state absorption in nanocomposite films of PbS stabilized in a synthetic glue matrix

    International Nuclear Information System (INIS)

    Strong nonlinear absorption is observed in nanocomposite films containing PbS nanocrystals of mean size of 3.3 nm stabilized in a commercial poly(vinyl acetate) glue by a novel and simple chemical route of synthesis. A significant blueshift of the optical absorption edge indicates strong quantum confinement. The mean nanocrystal size was characterized by x-ray diffraction and transmission electron microscopy. The surface structure of nanocrystals is analysed using infrared spectroscopy. The excitonic transitions are probed by photoacoustic spectroscopy and the results are analysed on the basis of theoretical calculations using envelope function formalism. Results of open aperture z-scan experiments suggest a model involving saturable absorption followed by two-photon absorption at a lower concentration while the data for a higher concentration fitted saturable absorption followed by three-photon absorption. Free carrier absorption due to two-photon-assisted excited state absorption appears to be the predominant mechanism of optical nonlinearity

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

    Science.gov (United States)

    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 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 absorption (p absorption was significantly correlated with that of peptides/amino acids absorption in WPH (r = 0.82, p absorption-promoting effect, to which PepT1 contributes.

  12. Population Diagnostics of a Hot NaBr Plasma by Detailed Simulation of Absorption Spectra

    Institute of Scientific and Technical Information of China (English)

    JIN Feng-Tao; ZENG Jiao-Long; YUAN Jian-Min

    2006-01-01

    @@ The experimental absorption spectra of a hot NaBr plasma are theoretically studied by using a detailed level accounting model The sodium and bromine absorption spectra have been well reproduced respectively in the approach of local thermodynamic equilibrium, in which the populations between and within ions are obtained by solving the Saha-Boltzmann equation.

  13. Graphene intracavity spaser absorption spectroscopy

    Science.gov (United States)

    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.

  14. Quantum-enhanced absorption refrigerators.

    Science.gov (United States)

    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

  15. Multistage quantum absorption heat pumps.

    Science.gov (United States)

    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.

  16. HI Absorption in Merger Remnants

    Science.gov (United States)

    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.

  17. A Group Increment Scheme for Infrared Absorption Intensities of Greenhouse Gases

    Science.gov (United States)

    Kokkila, Sara I.; Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

    2012-01-01

    A molecule's absorption in the atmospheric infrared (IR) window (IRW) is an indicator of its efficiency as a greenhouse gas. A model for estimating the absorption of a fluorinated molecule within the IRW was developed to assess its radiative impact. This model will be useful in comparing different hydrofluorocarbons and hydrofluoroethers contribution to global warming. The absorption of radiation by greenhouse gases, in particular hydrofluoroethers and hydrofluorocarbons, was investigated using ab initio quantum mechanical methods. Least squares regression techniques were used to create a model based on this data. The placement and number of fluorines in the molecule were found to affect the absorption in the IR window and were incorporated into the model. Several group increment models are discussed. An additive model based on one-carbon groups is found to work satisfactorily in predicting the ab initio calculated vibrational intensities.

  18. Absorption-line measurements of AGN outflows

    Science.gov (United States)

    Fields, Dale L.

    Investigations into the elemental abundances in two nearby active galaxies, the narrow-line Seyfert 1 Markarian 1044 and the Seyfert 1 Markarian 279, are reported. Spectra from three space-based observatories HST, FUSE, and CHANDRA, are used to measure absorption lines in material outflowing from the nucleus. I make multi-wavelength comparisons to better convert the ionic column densities into elemental column densities which can then be used to determine abundances (metallicities). Narrow-line Seyfert 1 galaxies are known to have extreme values of a number of properties compared to active galactic nuclei (AGNs) as a class. In particular, emission-line studies have suggested that NLS1s are unusually metal-rich compared to broad-line AGNs of comparable luminosity. To test these suggestions I perform absorption-line studies on the NLS1 Markarian 1044, a nearby and bright AGN. I use lines of H I, C IV, N V, and O VI to properly make the photoionization correction through the software Cloudy and determine abundances of Carbon, Nitrogen and Oxygen. I find two results. The first is that Markarian 1044 has a bulk metallicity greater than five times solar. The second is that the N/C ratio in Markarian 1044 is consistent with a solar mixture. This is in direct contradiction of extrapolations from local H II regions which state N/ C should scale with bulk metallicity. This implies a different enrichment history in Markarian 1044 than in the Galactic disk. I also report discovery of three new low-redshift Lya forest lines with log N HI >= 12:77 in the spectrum of Markarian 1044. This number is consistent with the 2.6 expected Lya forest lines in the path length to Markarian 1044. I also investigate the CHANDRA X-ray spectrum of Markarian 279, a broad-line Seyfert 1. I use a new code, PHASE, to self-consistently model the entire absorption spectrum simultaneously. Using solely the X-ray spectrum I am able to determine the physical parameters of this absorber to a degree only

  19. Energy absorption capabilities of composite sandwich panels under blast loads

    Science.gov (United States)

    Sankar Ray, Tirtha

    As blast threats on military and civilian structures continue to be a significant concern, there remains a need for improved design strategies to increase blast resistance capabilities. The approach to blast resistance proposed here is focused on dissipating the high levels of pressure induced during a blast through maximizing the potential for energy absorption of composite sandwich panels, which are a competitive structural member type due to the inherent energy absorption capabilities of fiber reinforced polymer (FRP) composites. Furthermore, the middle core in the sandwich panels can be designed as a sacrificial layer allowing for a significant amount of deformation or progressive failure to maximize the potential for energy absorption. The research here is aimed at the optimization of composite sandwich panels for blast mitigation via energy absorption mechanisms. The energy absorption mechanisms considered include absorbed strain energy due to inelastic deformation as well as energy dissipation through progressive failure of the core of the sandwich panels. The methods employed in the research consist of a combination of experimentally-validated finite element analysis (FEA) and the derivation and use of a simplified analytical model. The key components of the scope of work then includes: establishment of quantified energy absorption criteria, validation of the selected FE modeling techniques, development of the simplified analytical model, investigation of influential core architectures and geometric parameters, and investigation of influential material properties. For the parameters that are identified as being most-influential, recommended values for these parameters are suggested in conceptual terms that are conducive to designing composite sandwich panels for various blast threats. Based on reviewing the energy response characteristic of the panel under blast loading, a non-dimensional parameter AET/ ET (absorbed energy, AET, normalized by total energy

  20. Absorptive capacity and regional patterns of innovation

    OpenAIRE

    Abreu, Maria; Grinevich, Vadim; Kitson, Michael; Savona, Maria

    2008-01-01

    Executive Summary This paper considers whether differences in absorptive capacity at the firm-level are determinants of regional variations in innovation performance. Differences in firms’ absorptive capacity are also due to sectoral and technological specificities. Both firms’ absorptive capacity and sectoral structure differ widely across regions: this analysis focuses on the former while controlling for the latter aspect in order to evaluate regional differences in firms’ propensity to...